# Patent

## Title
Pseudo-block copolymers and process employing chain shuttling agent

## Abstract

A process for the polymerization of one or more addition polymerizable monomers to form a copolymer comprising multiple regions or segments of differentiated polymer composition or properties comprising contacting an addition polymerizable monomer or mixture of monomers under addition polymerization conditions with a composition comprising at least one olefin polymerization catalyst, a cocatalyst and a chain shuttling agent, said process being characterized by formation of at least some of the growing polymer chains under differentiated process conditions such that two or more blocks or segments formed within at least some of the resulting polymer are chemically or physically distinguishable.

## Background
CROSS REFERENCE STATEMENT
This application claims the benefit of U.S. Provisional Application No. 60/662,938, filed Mar. 17, 2005.


BACKGROUND OF THE INVENTION
The present invention relates to a process for polymerizing a monomer or mixtures of two or more monomers such as mixtures of ethylene and one or more comonomers, to form an interpolymer product having unique physical properties, to a process for preparing such interpolymers, and to the resulting polymer products. In another aspect, the invention relates to the articles prepared from these polymers. The inventive polymers comprise two or more differing regions or segments (blocks) causing the polymer to possess unique physical properties. These pseudo-block copolymers and polymeric blends comprising the same are usefully employed in the preparation of solid articles such as moldings, films, sheets, and foamed objects by molding, extruding, or other processes, and are useful as components or ingredients in adhesives, laminates, polymeric blends, and other end uses. The resulting products are used in the manufacture of components for automobiles, such as profiles, bumpers and trim parts; packaging materials; electric cable insulation, and other applications.
It has long been known that polymers containing a block-type structure often have superior properties compared to random copolymers and blends. For example, triblock copolymers of styrene and butadiene (SBS) and hydrogenated versions of the same (SEBS) have an excellent combination of heat resistance and elasticity. Other block copolymers are also known in the art. Generally, block copolymers known as thermoplastic elastomers (TPE) have desirable properties due to the presence of “soft” or elastomeric block segments connecting “hard” either crystallizable or glassy blocks in the same polymer. At temperatures up to the melt temperature or glass transition temperature of the hard segments, the polymers demonstrate elastomeric character. At higher temperatures, the polymers become flowable, exhibiting thermoplastic behavior. Known methods of preparing block copolymers include anionic polymerization and controlled free radical polymerization. Unfortunately, these methods of preparing block copolymers require sequential monomer addition and batch processing and the types of monomers that can be usefully employed in such methods are relatively limited. For example, in the anionic polymerization of styrene and butadiene to form a SBS type block copolymer, each polymer chain requires a stoichiometric amount of initiator and the resulting polymers have extremely narrow molecular weight distribution, Mw/Mn, preferably from 1.0 to 1.3. Additionally, anionic and free-radical processes are relatively slow, resulting in poor process economics.
It would be desirable to produce block copolymers catalytically, that is, in a process wherein more than one polymer molecule is produced for each catalyst or initiator molecule. In addition, it would be highly desirable to produce copolymers having properties resembling block copolymers from olefin monomers such as ethylene, propylene, and higher alpha-olefins that are generally unsuited for use in anionic or free-radical polymerizations. In certain of these polymers, it is highly desirable that some or all of the polymer blocks comprise amorphous polymers such as a copolymer of ethylene and a comonomer, especially amorphous random copolymers comprising ethylene and an α-olefin having 3, and especially 4, or more carbon atoms.
Previous researchers have stated that certain homogeneous coordination polymerization catalysts can be used to prepare polymers having a substantially “block-like” structure by suppressing chain-transfer during the polymerization, for example, by conducting the polymerization process in the absence of a chain transfer agent and at a sufficiently low temperature such that chain transfer by β-hydride elimination or other chain transfer processes is essentially eliminated. Under such conditions, the sequential addition of different monomers was said to result in formation of polymers having sequences or segments of different monomer content. Several examples of such catalyst compositions and processes are reviewed by Coates, Hustad, and Reinartz in Angew. Chem., Int. Ed., 41, 2236-2257 (2002) as well as US-A-2003/0114623.
Disadvantageously, such processes require sequential monomer addition and result in the production of only one polymer chain per active catalyst center, which limits catalyst productivity. In addition, the requirement of relatively low process temperatures increases the process operating costs, making such processes unsuited for commercial implementation. Moreover, the catalyst cannot be optimized for formation of each respective polymer type, and therefore the entire process results in production of polymer blocks or segments of less than maximal efficiency and/or quality. For example, formation of a certain quantity of prematurely terminated polymer is generally unavoidable, resulting in the forming of blends having inferior polymer properties. Accordingly, under normal operating conditions, for sequentially prepared block copolymers having Mw/Mn of 1.5 or greater, the resulting distribution of block lengths is relatively inhomogeneous, not a most probable distribution.
For these reasons, it would be highly desirable to provide a process for producing olefin copolymers comprising at least some quantity of blocks or segments having differing physical properties in a process using coordination polymerization catalysts capable of operation at high catalytic efficiencies. In addition, it would be desirable to provide a process and resulting copolymers wherein insertion of terminal blocks or sequencing of blocks within the polymer can be influenced by appropriate selection of process conditions. Finally, if would be highly desirable to be able to use a continuous process for production of block copolymers.
The use of certain metal alkyl compounds and other compounds, such as hydrogen, as chain transfer agents to interrupt chain growth in olefin polymerizations is well known in the art. In addition, it is known to employ such compounds, especially aluminum alkyl compounds, as scavengers or as cocatalysts in olefin polymerizations. In Macromolecules, 33, 9192-9199 (2000) the use of certain aluminum trialkyl compounds as chain transfer agents in combination with certain paired zirconocene catalyst compositions resulted in polypropylene mixtures containing small quantities of polymer fractions containing both isotactic and atactic chain segments. In Liu and Rytter, Macromolecular Rapid Comm., 22, 952-956 (2001) and Bruaseth and Rytter, Macromolecules, 36, 3026-3034 (2003) mixtures of ethylene and 1-hexene were polymerized by a similar catalyst composition containing trimethylaluminum chain transfer agent. In the latter reference, the authors summarized the prior art studies in the following manner (some citations omitted):

    
    
        “Mixing of two metallocenes with known polymerization behavior can be used to control polymer microstructure. Several studies have been performed of ethene polymerization by mixing two metallocenes. Common observations were that, by combining catalysts which separately give polyethene with different Mw, polyethene with broader and in some cases bimodal MWD can be obtained. [S]oares and Kim (J. Polym. Sci., Part A: Polym. Chem., 38, 1408-1432 (2000)) developed a criterion in order to test the MWD bimodality of polymers made by dual single-site catalysts, as exemplified by ethene/1-hexene copolymerization of the mixtures Et(Ind)2ZrCl2/Cp2HfCl2 and Et(Ind)2ZrCl2/CGC (constrained geometry catalyst) supported on silica. Heiland and Kaminsky (Makromol. Chem., 193, 601-610 (1992)) studied a mixture of Et-(Ind)2ZrCl2 and the hafnium analogue in copolymerization of ethene and 1-butene.
        These studies do not contain any indication of interaction between the two different sites, for example, by readsorption of a terminated chain at the alternative site. Such reports have been issued, however, for polymerization of propene. Chien et al. (J. Polym. Sci. Part A: Polym. Chem., 37, 2439-2445 (1999), Makromol., 30, 3447-3458 (1997)) studied propene polymerization by homogeneous binary zirconocene catalysts. A blend of isotactic polypropylene (i-PP), atactic polypropylene (a-PP), and a stereoblock fraction (i-PP-b-a-PP) was obtained with a binary system comprising an isospecific and an aspecific precursor with a borate and TIBA as cocatalyst. By using a binary mixture of isospecific and syndiospecific zirconocenes, a blend of isotactic polypropylene (i-PP), syndiotactic polypropylene (s-PP), and a stereoblock fraction (i-PP-b-s-PP) was obtained. The mechanism for formation of the stereoblock fraction was proposed to involve the exchange of propagating chains between the two different catalytic sites. Przybyla and Fink (Acta Polym., 50, 77-83 (1999)) used two different types of metallocenes (isospecific and syndiospecific) supported on the same silica for propene polymerization. They reported that, with a certain type of silica support, chain transfer between the active species in the catalyst system occurred, and stereoblock PP was obtained. Lieber and Brintzinger (Macromol. 3, 9192-9199 (2000)) have proposed a more detailed explanation of how the transfer of a growing polymer chain from one type of metallocene to another occurs. They studied propene polymerization by catalyst mixtures of two different ansa-zirconocenes. The different catalysts were first studied individually with regard to their tendency toward alkyl-polymeryl exchange with the allylaluminum activator and then pairwise with respect to their capability to produce polymers with a stereoblock structure. They reported that formation of stereoblock polymers by a mixture of zirconocene catalysts with different stereoselectivities is contingent upon an efficient polymeryl exchange between the Zr catalyst centers and the Al centers of the cocatalyst.”
    
    


Brusath and Rytter then disclosed their own observations using paired zirconocene catalysts to polymerize mixtures of ethylene/1-hexene and reported the effects of the influence of the dual site catalyst on polymerization activity, incorporation of comonomer, and polymer microstructure using methylalumoxane cocatalyst.
Analysis of the foregoing results indicate that Rytter and coworkers likely failed to utilize combinations of catalyst, cocatalyst, and third components that were capable of readsorption of the polymer chain from the chain transfer agent onto both of the active catalytic sites, that is, two-way readsorption. While indicating that chain termination due to the presence of trimethylaluminum likely occurred with respect to polymer formed from the catalyst incorporating minimal comonomer, and thereafter that polymeryl exchange with the more open catalytic site followed by continued polymerization likely occurred, evidence of the reverse flow of polymer ligands appeared to be lacking in the reference. In fact, in a later communication, Rytter, et. al., Polymer, 45, 7853-7861 (2004), it was reported that no chain transfer between the catalyst sites actually took place in the earlier experiments. Similar polymerizations were reported in WO98/34970.
In U.S. Pat. Nos. 6,380,341 and 6,169,151, use of a “fluxional” metallocene catalyst, that is a metallocene capable of relatively facile conversion between two stereoisomeric forms having differing polymerization characteristics such as differing reactivity ratios was said to result in production of olefin copolymers having a “blocky” structure. Disadvantageously, the respective stereoisomers of such metallocenes generally fail to possess significant difference in polymer formation properties and are incapable of forming both highly crystalline and amorphous block copolymer segments, for example, from a given monomer mixture under fixed reaction conditions. Moreover, because the relative ratio of the two “fluxional” forms of the catalyst cannot be varied, there is no ability, using “fluxional” catalysts, to vary polymer block composition or the ratio of the respective blocks. For certain applications, it is desirable to produce polymers having terminal blocks that are highly crystalline, functionalized or more readily functionalized, or that possess other distinguishing properties. For example, it is believed that polymers wherein the terminal segments or blocks are crystalline or glassy possess improved abrasion resistance. In addition, polymers wherein the blocks having amorphous properties are internal or primarily connected between crystalline or glassy blocks, have improved elastomeric properties, such as improved retractive force and recovery, particularly at elevated temperatures.
In JACS, 2004, 126, 10701-10712, Gibson, et al discuss the effects of “catalyzed living polymerization” on molecular weight distribution. The authors define catalyzed living polymerization in this manner:

    
    
        “ . . . if chain transfer to aluminum constitutes the sole transfer mechanism and the exchange of the growing polymer chain between the transition metal and the aluminum centers is very fast and reversible, the polymer chains will appear to be growing on the aluminum centers. This can then reasonably be described as a catalyzed chain growth reaction on aluminum . . . . An attractive manifestation of this type of chain growth reaction is a Poisson distribution of product molecular weights, as opposed to the Schulz-Flory distribution that arises when β-H transfer accompanies propagation.”
    
    


The authors reported the results for the catalyzed living homopolymerization of ethylene using an iron containing catalyst in combination with ZnEt2, ZnMe2, or Zn(i-Pr)2. Homoleptic alkyls of aluminum, boron, tin, lithium, magnesium and lead did not induce catalyzed chain growth. Using GaMe3 as cocatalyst resulted in production of a polymer having a narrow molecular weight distribution. However, after analysis of time-dependent product distribution, the authors concluded this reaction was, “not a simple catalyzed chain growth reaction.” Accordingly, the product would not have constituted a pseudo-block copolymer. Similar processes employing single catalysts have been described in U.S. Pat. Nos. 5,210,338, 5, 276,220, and 6,444,867.
Earlier workers had made similar claims to forming block copolymers using a single Ziegler-Natta type catalyst in multiple reactors arranged in series. Examples of such teachings include U.S. Pat. Nos. 3,970,719 and 4,039,632. It is now known that no substantial block copolymer formation takes place under these reaction conditions.
In U.S. Pat. Nos. 6,319,989 and 6,683,149, the use of two loop reactors connected in series and operating under differing polymerization conditions to prepare either broad or narrow molecular weight polymer products was disclosed. The references fail to disclose the use of chain transfer agents and the formation of pseudo-block copolymer products.
Accordingly, there remains a need in the art for a polymerization process that is capable of preparing copolymers having properties approximating those of linear multi-block copolymers, in a high yield process adapted for commercial utilization. Moreover, it would be desirable if there were provided an improved process for preparing polymers, especially copolymers of two or more comonomers such as ethylene and one or more comonomers, by the use of a shuttling agent to introduce block-like properties in the resulting polymer (pseudo-block copolymers). In addition it would be desirable to provide such an improved process that is capable of preparing copolymers having a relatively narrow molecular weight distribution and non-random distribution of polymer segments or regions. Finally, it would be desirable to provide an improved process for preparing the foregoing desirable pseudo-block copolymer products in a continuous process.
SUMMARY OF THE INVENTION
According to the present invention there are now provided a process for the polymerization of one or more addition polymerizable monomers, preferably of two or more addition polymerizable monomers, especially ethylene and at least one copolymerizable comonomer, propylene and at least one copolymerizable comonomer, or 4-methyl-1-pentene and at least one copolymerizable comonomer, to form a copolymer comprising multiple regions of differentiated polymer composition or properties, especially regions comprising differing comonomer incorporation, said process comprising contacting an addition polymerizable monomer or mixture of monomers under addition polymerization conditions with a composition comprising at least one olefin polymerization catalyst, a cocatalyst and a chain shuttling agent, said process being characterized by formation of at least some of the growing polymer chains under differentiated process conditions such that two or more blocks or segments formed within at least some of the resulting polymer are chemically or physically distinguishable.
In another embodiment of the invention there is provided a copolymer, especially such a copolymer comprising in polymerized form ethylene and a copolymerizable comonomer, propylene and at least one copolymerizable comonomer, or 4-methyl-1-pentene and at least one copolymerizable comonomer, said copolymer comprising two or more intramolecular regions comprising differing chemical or physical properties, especially regions of differentiated comonomer incorporation. Highly preferably the copolymer possesses a molecular weight distribution, Mw/Mn, of less than 3.0, preferably less than 2.8.
In a still further embodiment of the present invention, there is provided a polymer mixture comprising: (1) an organic or inorganic polymer, preferably a homopolymer of ethylene or of propylene and/or a copolymer of ethylene or propylene and a copolymerizable comonomer, and (2) a pseudo-block copolymer according to the present invention or prepared according to the process of the present invention. In a desirable embodiment component (1) is a matrix polymer comprising high density polyethylene or isotactic polypropylene and component (2) is an elastomeric pseudo-block copolymer. In a preferred embodiment, component (2) comprises occlusions of the matrix polymer formed during compounding of components (1) and (2).



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of the process of copolymer formation according to the present invention.
FIG. 2 is a schematic representation of a continuous loop reactor suitable for use in the present invention.



DETAILED DESCRIPTION OF THE INVENTION
All references to the Periodic Table of the Elements herein shall refer to the Periodic Table of the Elements, published and copyrighted by CRC Press, Inc., 2003. Also, any references to a Group or Groups shall be to the Group or Groups reflected in this Periodic Table of the Elements using the IUPAC system for numbering groups. Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight. For purposes of United States patent practice, the contents of any patent, patent application, or publication referenced herein are hereby incorporated by reference in their entirety (or the equivalent US version thereof is so incorporated by reference) especially with respect to the disclosure of synthetic techniques, definitions (to the extent not inconsistent with any definitions provided herein) and general knowledge in the art.
The term “comprising” and derivatives thereof is not intended to exclude the presence of any additional portion, component, step or procedure, whether or not the same is disclosed herein. In order to avoid any doubt, all compositions claimed herein through use of the term “comprising” may include any additional additive, adjuvant, or compound whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of” excludes from the scope of any succeeding recitation any other portion, component, step or procedure, excepting those that are not essential to operability. The term “consisting of” excludes any portion, component, step or procedure not specifically delineated or listed. The term “or”, unless stated otherwise, refers to the listed members individually as well as in any combination.
The term “polymer”, includes both homopolymers, that is, homogeneous polymers prepared from a single monomer, and copolymers (interchangeably referred to herein as interpolymers), meaning polymers prepared by reaction of at least two monomers or otherwise containing chemically differentiated segments or blocks therein even if formed from a single monomer. More specifically, the term “polyethylene” includes homopolymers of ethylene and copolymers of ethylene and one or more C3-8 α-olefins. The term “crystalline” if employed, refers to a polymer that possesses a first order transition or crystalline melting point (Tm) as determined by differential scanning calorimetry (DSC) or equivalent technique. The term may be used interchangeably with the term “semicrystalline”. The term “amorphous” refers to a polymer lacking a crystalline melting point.
The term “pseudo-block copolymer” refers to a copolymer comprising two or more regions or segments (referred to as “blocks”) of differing chemical or physical property, such as variable comonomer content, crystallinity, density, tacticity, regio-error, or other property, preferably joined in a linear manner, that is, a polymer comprising blocks which are joined end-to-end, rather than in pendent or grafted fashion. The various blocks are not necessarily of identical chemical composition, but vary, at least somewhat, in one or more of the foregoing respects, from the composition of adjacent blocks or regions. Compared to random copolymers, the polymers of the invention possess sufficient differences in chemical properties, especially crystallinity, between blocks or segments, to achieve many of the desired properties of true block copolymers, such as thermoplastic elastomeric properties, while at the same time being amenable to preparation in conventional olefin polymerization processes, especially continuous solution polymerization processes employing catalytic quantities of polymerization catalysts. Compared to block copolymers of the prior art, including copolymers produced by sequential monomer addition, fluxional catalysts, or anionic polymerization techniques, the copolymers of the invention are characterized by unique distributions of polymer polydispersity (PDI or Mw/Mn), block length distribution, and, most significantly, block composition distribution. This is due, in a preferred embodiment, to the effect of the use of a shuttling agent(s) in combination with a high activity metal complex based polymerization catalyst in a polymerization process having multiple polymerization zones or continuous variation in one or more polymerization conditions. More specifically, the polymers desirably possess PDI from 1.7 to 2.9, preferably from 1.8 to 2.5.
In addition, the pseudo-block copolymers of the invention desirably possess a PDI fitting a Schutz-Flory distribution rather than a Poisson distribution. The use of the present polymerization process results in a product having a polydisperse block distribution, a polydisperse distribution of block sizes, and/or a polydisperse block composition distribution. This ultimates in the formation of polymer products having improved and distinguishable physical properties. The theoretical benefits of a polydisperse block distribution have been previously modeled and discussed in Potemkin, Physical Review E (1998) 57(6), p. 6902-6912, and Dobrynin, J. Chem. Phys. (1997) 107(21), p 9234-9238.
As used herein with respect to a chemical compound, unless specifically indicated otherwise, the singular includes all isomeric forms and vice versa (for example, “hexane”, includes all isomers of hexane individually or collectively). The terms “compound” and “complex” are used interchangeably herein to refer to organic-, inorganic- and organometal compounds. The term, “atom” refers to the smallest constituent of an element regardless of ionic state, that is, whether or not the same bears a charge or partial charge or is bonded to another atom. The term “heteroatom” refers to an atom other than carbon or hydrogen. Preferred heteroatoms include: F, Cl, Br, N, O, P, B, S, Si, Sb, Al, Sn, As, Se and Ge.
The term, “hydrocarbyl” refers to univalent substituents containing only hydrogen and carbon atoms, including branched or unbranched, saturated or unsaturated, cyclic or noncyclic species. Examples include alkyl-, cycloalkyl-, alkenyl-, alkadienyl-, cycloalkenyl-, cycloalkadienyl-, aryl-, and alkynyl-groups. “Substituted hydrocarbyl” refers to a hydrocarbyl group that is substituted with one or more nonhydrocarbyl substituent groups. The terms, “heteroatom containing hydrocarbyl” or “heterohydrocarbyl” refer to univalent groups in which at least one atom other than hydrogen or carbon is present along with one or more carbon atom and one or more hydrogen atoms. The term “heterocarbyl” refers to groups containing one or more carbon atoms and one or more heteroatoms and no hydrogen atoms. The bond between the carbon atom and any heteroatom as well as the bonds between any two heteroatoms, may be saturated or unsaturated. Thus, an alkyl group substituted with a heterocycloalkyl-, substituted heterocycloalkyl-, heteroaryl-, substituted heteroaryl-, alkoxy-, aryloxy-, dihydrocarbylboryl-, dihydrocarbylphosphino-, dihydrocarbylamino-, trihydrocarbylsilyl-, hydrocarbylthio-, or hydrocarbylseleno-group is within the scope of the term heteroalkyl. Examples of suitable heteroalkyl groups include cyano-, benzoyl-, (2-pyridyl)methyl-, and trifluoromethyl-groups.
As used herein the term “aromatic” refers to a polyatomic, cyclic, conjugated ring system containing (4δ+2) π-electrons, wherein δ is an integer greater than or equal to 1. The term “fused” as used herein with respect to a ring system containing two or more polyatomic, cyclic rings means that with respect to at least two rings thereof, at least one pair of adjacent atoms is included in both rings. The term “aryl” refers to a monovalent aromatic substituent which may be a single aromatic ring or multiple aromatic rings which are fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety. The aromatic ring(s) may include phenyl, naphthyl, anthracenyl, and biphenyl, among others.
“Substituted aryl” refers to an aryl group in which one or more hydrogen atoms bound to any carbon is replaced by one or more functional groups such as alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocycloalkyl, substituted heterocycloalkyl, halogen, alkylhalos (for example, CF3), hydroxy, amino, phosphido, alkoxy, amino, thio, nitro, and both saturated and unsaturated cyclic hydrocarbons which are fused to the aromatic ring(s), linked covalently or linked to a common group such as a methylene or ethylene moiety. The common linking group may also be a carbonyl as in benzophenone or oxygen as in diphenylether or nitrogen in diphenylamine.
The term, “comonomer incorporation index”, refers to the percent comonomer incorporated into a copolymer prepared under representative monomer/comonomer polymerization conditions by the catalyst under consideration in the absence of other polymerization catalysts, ideally under steady-state, continuous solution polymerization conditions at greater than 95 percent monomer conversion and greater than 0.01 percent comonomer conversion. The selection of metal complexes or catalyst compositions having the greatest difference in comonomer incorporation indices under the different polymerization conditions results in copolymers from two or more monomers having the largest difference in block or segment properties, such as density.
In certain circumstances the comonomer incorporation index may be determined directly, for example by the use of NMR spectroscopic techniques. Often, however, any difference in comonomer incorporation must be indirectly determined. For polymers formed from multiple monomers this may be accomplished by various techniques based on monomer reactivities.
For copolymers produced by a given catalyst, the relative amounts of comonomer and monomer in the copolymer and hence the copolymer composition is determined by relative rates of reaction of comonomer and monomer. Mathematically the molar ratio of comonomer to monomer is given by




  
    
      
        
          
            F
            2
          
          
            F
            1
          
        
        =
        
          
            
              (
              
                
                  [
                  comonomer
                  ]
                
                
                  [
                  monomer
                  ]
                
              
              )
            
            polymer
          
          =
          
            
              R
              
                p
                ⁢
                
                  
                
                ⁢
                2
              
            
            
              R
              
                p
                ⁢
                
                  
                
                ⁢
                1
              
            
          
        
      
    
    
      
        (
        1
        )
      
    
  




Here Rp2 and Rp1 are the rates of polymerization of comonomer and monomer respectively and F2 and F1 are the mole fractions of each in the copolymer. Because F1+F2=1 we can rearrange this equation to




  
    
      
        
          F
          2
        
        =
        
          
            R
            
              p
              ⁢
              
                
              
              ⁢
              2
            
          
          
            
              R
              
                p
                ⁢
                
                  
                
                ⁢
                1
              
            
            +
            
              R
              
                p
                ⁢
                
                  
                
                ⁢
                2
              
            
          
        
      
    
    
      
        (
        2
        )
      
    
  




The individual rates of polymerization of comonomer and monomer are typically complex functions of temperature, catalyst, and monomer/comonomer concentrations. In the limit as comonomer concentration in the reaction media drops to zero, Rp2 drops to zero, F2 becomes zero and the polymer consists of pure monomer. In the limiting case of no monomer in the reactor Rp1 becomes zero and F2 is one (provided the comonomer can polymerize alone).
For most homogeneous catalysts the ratio of comonomer to monomer in the reactor largely determines polymer composition as determined according to either the Terminal Copolymerization Model or the Penultimate Copolymerization Model.
For random copolymers in which the identity of the last monomer inserted dictates the rate at which subsequent monomers insert, the terminal copolymerization model is employed. In this model insertion reactions of the type




where C* represents the catalyst, Mi represents monomer i, and kij is the rate constant having the rate equation:

Rpij=kij└ . . . MiC*┘[Mj]  (4).

The comonomer mole fraction (i=2) in the reaction media is defined by the equation:




  
    
      
        
          f
          2
        
        =
        
          
            
              [
              
                M
                2
              
              ]
            
            
              
                [
                
                  M
                  1
                
                ]
              
              +
              
                [
                
                  M
                  2
                
                ]
              
            
          
          .
        
      
    
    
      
        (
        5
        )
      
    
  




A simplified equation for comonomer composition can be derived as disclosed in George Odian, Principles of Polymerization, Second Edition, John Wiley and Sons, 1970, as follows:




  
    
      
        
          F
          2
        
        =
        
          
            
              
                
                  
                    r
                    1
                  
                  ⁡
                  
                    (
                    
                      1
                      -
                      
                        f
                        2
                      
                    
                    )
                  
                
                2
              
              +
              
                
                  (
                  
                    1
                    -
                    
                      f
                      2
                    
                  
                  )
                
                ⁢
                
                  f
                  2
                
              
            
            
              
                
                  
                    r
                    1
                  
                  ⁡
                  
                    (
                    
                      1
                      -
                      
                        f
                        2
                      
                    
                    )
                  
                
                2
              
              +
              
                2
                ⁢
                
                  (
                  
                    1
                    -
                    
                      f
                      
                        2
                        )
                      
                    
                  
                  )
                
                ⁢
                
                  f
                  2
                
              
              +
              
                
                  r
                  2
                
                ⁢
                
                  f
                  2
                  2
                
              
            
          
          .
        
      
    
    
      
        (
        6
        )
      
    
  




From this equation the mole fraction of comonomer in the polymer is solely dependent on the mole fraction of comonomer in the reaction media and two temperature dependent reactivity ratios defined in terms of the insertion rate constants as:




  
    
      
        
          
            r
            1
          
          =
          
            
              k
              11
            
            
              k
              12
            
          
        
        ⁢
        
          

        
        ⁢
        
          
            r
            2
          
          =
          
            
              
                k
                22
              
              
                k
                21
              
            
            .
          
        
      
    
    
      
        (
        7
        )
      
    
  




Alternatively, in the penultimate copolymerization model, the identities of the last two monomers inserted in the growing polymer chain dictate the rate of subsequent monomer insertion. The polymerization reactions are of the form:




and the individual rate equations are:

Rpijk=Kijk└ . . . MiMj=C*┘[Mk]  (9)

The comonomer content can be calculated (again as disclosed in George Odian, Supra.) as:




  
    
      
        
          
            (
            
              1
              -
              
                F
                2
              
            
            )
          
          
            F
            2
          
        
        =
        
          
            1
            +
            
              
                
                  r
                  1
                  ′
                
                ⁢
                
                  X
                  ⁡
                  
                    (
                    
                      
                        
                          r
                          1
                        
                        ⁢
                        X
                      
                      +
                      1
                    
                    )
                  
                
              
              
                (
                
                  
                    
                      r
                      1
                      ′
                    
                    ⁢
                    X
                  
                  +
                  1
                
                )
              
            
          
          
            1
            +
            
              
                
                  r
                  2
                  ′
                
                ⁡
                
                  (
                  
                    
                      r
                      2
                    
                    +
                    X
                  
                  )
                
              
              
                X
                ⁡
                
                  (
                  
                    
                      r
                      2
                      ′
                    
                    +
                    X
                  
                  )
                
              
            
          
        
      
    
    
      
        (
        10
        )
      
    
  




where X is defined as:




  
    
      
        X
        =
        
          
            (
            
              1
              -
              
                f
                2
              
            
            )
          
          
            f
            2
          
        
      
    
    
      
        (
        11
        )
      
    
  




and the reactivity ratios are defined as:




  
    
      
        
          
            r
            1
          
          =
          
            
              k
              111
            
            
              k
              112
            
          
        
        ⁢
        
          

        
        ⁢
        
          
            r
            1
            ′
          
          =
          
            
              k
              211
            
            
              k
              212
            
          
        
        ⁢
        
          

        
        ⁢
        
          
            r
            2
          
          =
          
            
              k
              222
            
            
              k
              221
            
          
        
        ⁢
        
          

        
        ⁢
        
          
            r
            2
            ′
          
          =
          
            
              
                k
                122
              
              
                k
                121
              
            
            .
          
        
      
    
    
      
        (
        12
        )
      
    
  




For this model as well the polymer composition is a function only of temperature dependent reactivity ratios and comonomer mole fraction in the reactor. The same is also true when reverse comonomer or monomer insertion may occur or in the case of the interpolymerization of more than two monomers.
Reactivity ratios for use in the foregoing models may be predicted using well known theoretical techniques or empirically derived from actual polymerization data. Suitable theoretical techniques are disclosed, for example, in B. G. Kyle, Chemical and Process Thermodynamics, Third Addition, Prentice-Hall, 1999 and in Redlich-Kwong-Soave (RKS) Equation of State, Chemical Engineering Science, 1972, pp 1197-1203. Commercially available software programs may be used to assist in deriving reactivity ratios from experimentally derived data. One example of such software is Aspen Plus from Aspen Technology, Inc., Ten Canal Park, Cambridge, Mass. 02141-2201 USA.
In a preferred embodiment, the polymers of the invention possess a most probable distribution of block lengths and block compositions. Preferred polymers according to the invention are pseudo-block copolymers containing 4 or more blocks or segments including terminal blocks. The respective blocks or segments need not be chemically similar, and more generally are characterized by a distribution of properties. The invention involves the concept of using chain shuttling as a way to prolong the lifetime of a polymer chain such that a substantial fraction of the polymer chains experience different polymerization conditions. Thus, instead of forming an intermolecular polymer blend, at least a portion of the polymer resulting from the present process comprises differentiated polymer segments arranged intramolecularly. Because the various regions need not possess identical chemical or physical properties (that is, each differing region may be unique) and/or a portion of the polymer may comprise random monomer incorporation, the product is referred to as a pseudo-block copolymer.
In contrast with the previously discussed sequential polymerization techniques wherein no chain shuttling agent is utilized, polymer products can now be obtained according to the present invention by selecting highly active catalyst compositions capable of rapid transfer of polymer segments both to and from a suitable chain shuttling agent such that polymer blocks or regions of the resulting catalyst possess distinguishable polymer properties. Thus, due to the presence of a chain shuttling agent capable of rapid and efficient exchange of growing polymer chains the growing polymer experiences discontinuous polymer growth, such that intramolecular regions of the polymer are formed under multiple polymerization conditions.
The following mathematical treatment of the resulting polymers is based on theoretically derived parameters that are believed to apply to the present invented polymers and demonstrate that, especially in a steady-state, continuous reactor having differing polymerization conditions to which the growing polymer is exposed, especially in a repetitive manner, the block lengths of the polymer being formed at any given point in the reactor will each conform to a most probable distribution, derived in the following manner, wherein at any given point in the reactor pi is the probability of propagation with respect to block sequences from catalyst i. The theoretical treatment is based on standard assumptions and methods known in the art and used in predicting the effects of polymerization kinetics on molecular architecture, including the use of mass action reaction rate expressions that are not affected by chain or block lengths, and the assumption that polymer chain growth is completed in a very short time compared to the mean reactor residence time. Such methods have been previously disclosed in W. H. Ray, J. Macromol. Sci. Rev. Macromol. Chem., C8, 1 (1972) and A. E. Hamielec and J. F. MacGregor, “Polymer Reaction Engineering”, K. H. Reichert and W. Geisler, Eds., Hanser, Munich, 1983. In addition it is assumed each incidence of the chain shuttling reaction results in the formation of a new polymer block, regardless of which catalyst engages in the shuttling, so that adjacent blocks formed by the same catalyst are counted as different blocks. For catalyst i, the fraction of sequences of length n being produced at any given point in the reactor is given by Xi[n], where n is an integer from 1 to infinity representing the total number of monomer units in the block.




  
    
      
        
          
        
      
    
    
      
        
          
        
      
    
  
  ⁢
  
    
      
        
          
            
              X
              i
            
            ⁡
            
              [
              n
              ]
            
          
          =
          
          ⁢
          
            
              (
              
                1
                -
                
                  p
                  i
                
              
              )
            
            ⁢
            
              p
              i
              
                (
                
                  n
                  -
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                )
              
            
          
        
      
      
        
          
          ⁢
          
            most
            ⁢
            
              
            
            ⁢
            probable
            ⁢
            
              
            
            ⁢
            distribution
            ⁢
            
              
            
            ⁢
            of
            ⁢
            
              
            
            ⁢
            block
            ⁢
            
              
            
            ⁢
            lengths
          
        
      
    
    
      
        
          
            N
            i
          
          =
          
          ⁢
          
            1
            
              1
              -
              
                p
                i
              
            
          
        
      
      
        
          
          ⁢
          
            number
            ⁢
            
              
            
            ⁢
            average
            ⁢
            
              
            
            ⁢
            block
            ⁢
            
              
            
            ⁢
            length
          
        
      
    
  




If more than one catalyst is present, at any given point in the reactor each catalyst has a probability of propagation (pi) and therefore has a unique average block length and distribution for polymer being made at that point. In a most preferred embodiment the probability of propagation is defined as:




  
    p
    i
  
  =
  
    
      Rp
      ⁡
      
        [
        i
        ]
      
    
    
      
        Rp
        ⁡
        
          [
          i
          ]
        
      
      +
      
        Rt
        ⁡
        
          [
          i
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      +
      
        Rs
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        for each catalyst i={1, 2 . . . }, where,
    
    


Rp[i]=Local rate of monomer consumption by catalyst i, (moles/L/time),
Rt[i]=Total rate of chain transfer and termination for catalyst i, (moles/L/time), and
Rs[i]=Local rate of chain shuttling with dormant polymer, (moles/L/time).
For a given point in the reactor the local monomer consumption or polymer propagation rate, Rp[i], is defined using an apparent rate constant, kpi, multiplied by a total monomer concentration, [M], and multiplied by the local concentration of catalyst i, [Ci], as follows:

Rp[i]= kpi[M][Ci]

For a given point in the reactor, the local chain transfer, termination, and shuttling rate is expressed below with local values for chain transfer to hydrogen (H2), beta hydride elimination, and chain transfer to chain shuttling agent (CSA). The quantities [H2] and [CSA] are local molar concentrations and each subscripted k value is a rate constant for the given point in the reactor

Rt[i]=kH2i[H2][Ci]+kβi[Ci]+kai[CSA][Ci]

Dormant polymer chains are created when a polymer moiety transfers to a CSA and all CSA moieties that react are assumed to each be paired with a dormant polymer chain. The rate of chain shuttling of dormant polymer with catalyst i is given as follows, where [CSAf] is the feed concentration of CSA, and the quantity ([CSAf]−[CSA]) represents the concentration of dormant polymer chains:

Rs[i]=kai[Ci]([CSAf]−[CSA])

The overall block length distribution for the final effluent polymer is a sum of the local instantaneous block length distribution given previously by Xi[n], weighted by the local polymer production rate for catalyst i. This means that a greater diversity of polymerization conditions will have a broadening affect on the overall block length distribution.
Monomers
Suitable monomers for use in preparing the copolymers of the present invention include any addition polymerizable monomer, preferably any olefin monomer, and most preferably ethylene and at least one copolymerizable comonomer, propylene and at least one copolymerizable comonomer, or 4-methyl-1-pentene and at least one copolymerizable comonomer. Examples of suitable monomers include straight-chain or branched α-olefins of 2 to 30, preferably 3 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexane, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene; cycloolefins of 3 to 30, preferably 3 to 20 carbon atoms, such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, and 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene; di- and poly-olefins, such as butadiene, isoprene, 4-methyl-1,3-pentadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene, 1,3-hexadiene, 1,3-octadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, ethylidene norbornene, vinyl norbornene, dicyclopentadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, and 5,9-dimethyl-1,4,8-decatriene; aromatic vinyl compounds such as mono or poly alkylstyrenes (including styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene and p-ethylstyrene), and functional group-containing derivatives, such as methoxystyrene, ethoxystyrene, vinylbenzoic acid, methyl vinylbenzoate, vinylbenzyl acetate, hydroxystyrene, o-chlorostyrene, p-chlorostyrene, divinylbenzene, 3-phenylpropene, 4-phenylpropene and α-methylstyrene, vinylchloride, 1,2-difluoroethylene, 1,2-dichloroethylene, tetrafluoroethylene, and 3,3,3-trifluoro-1-propene.
Chain Shuttling Agents
The term, “shuttling agent” or “chain shuttling agent”, refers to a compound or mixture of compounds that is capable of causing polymeryl transfer between the various active catalyst sites under the conditions of the polymerization. That is, transfer of a polymer fragment occurs both to and from an active catalyst site in a facile manner. In contrast to a shuttling agent, a “chain transfer agent” causes termination of polymer chain growth and amounts to a one-time transfer of growing polymer from the catalyst to the transfer agent. Desirably, the intermediate formed between the chain shuttling agent and the polymeryl chain is sufficiently stable that chain termination is relatively rare. Desirably, less than 10 percent, preferably less than 50 percent, more preferably less than 75 percent and most desirably less than 90 percent of shuttling agent-polymeryl products are terminated prior to attaining 3 distinguishable, intramolecular polymer segments or blocks.
While attached to the growing polymer chain, the shuttling agent desirably does not alter the polymer structure or incorporate additional monomer. That is, the shuttling agent does not also possess significant catalytic properties for the polymerization of interest. Rather, the shuttling agent forms a metal-alkyl or other type interaction with the polymer moiety, for a time period such that a slightly different polymer composition is formed after transfer of the polymer moiety back to an active polymerization catalyst site. As a consequence, the subsequently formed polymer region possesses a distinguishable physical or chemical property, such as a difference in comonomer composition distribution, crystallinity, density, tacticity, regio-error, or other property. Subsequent repetitions of the foregoing process can result in formation of segments or blocks having differing properties, or a repetition of a previously formed polymer composition, depending on the rates of polymeryl exchange and transport within the reactor. The polymers of the invention desirably are characterized by individual blocks or segments having a continuously variable composition distribution. That is, adjacent blocks have slightly altered composition within the polymer chains. The composition distribution or other physical or chemical property of the various blocks according to the present invention is continuously varying, due to the gradient or variation in one or more process conditions between different regions of the reactor.
The foregoing process is schematically represented for a single catalyst system in FIG. 1, where catalyst A, 10, is used to prepare a first polymer moiety, 12, under a first set of polymerization conditions. The polymerization is interrupted and the growing polymer transferred to a chain shuttling agent B, the combination being illustrated as, 14, and at a subsequent time, back to a catalyst A now exposed to polymerization conditions 2, said combination being identified as, 16. Polymerization condition 2 is different in at least one respect, preferably with respect to comonomer/monomer ratio, compared to polymerization condition 1. Polymerization commences under condition 2 but is again interrupted and the growing polymer transferred again to chain shuttling agent B, said new combination being illustrated as, 18, and subsequently, back once again to catalyst A, now exposed to polymerization condition 3. The growing polymer chain and active catalyst site are illustrated as, 20. Highly likely, polymerization condition 3 is dissimilar to both polymerization condition 1 and polymerization condition 2. Accordingly, it may be seen that multiple transfers of growing polymer may occur during the process of the invention and polymer segments within the same polymer are formed under multiple polymerization conditions. Ideally, the rate of chain shuttling is equivalent to or faster than the rate of polymer termination, even up to 10 or even 100 times faster than the rate of polymer termination. This permits formation of multiple polymer blocks on the same time scale as polymer propagation.
By selecting different shuttling agents or mixtures of agents with a catalyst, by altering the comonomer composition, temperature, pressure, optional chain terminating agent such as H2, or other reaction conditions in multiple regions of a reactor, polymer products having segments of continuously varying densities or comonomer concentrations, block lengths, block composition distributions, and/or other distinguishing property can be prepared. For example, if the activity of the shuttling agent is low relative to the catalyst polymer chain propagation rate, the resulting copolymer will differ in composition distribution from a copolymer resulting from the use of a shuttling agent that is very fast relative to polymer chain propagation. In the former, the block lengths will tend to increase and possess greater internal variation compared to products made under the latter conditions. In a typical continuous solution polymerization reactor, the polymerization conditions will be continuously shifting between two extremes and the resulting polymer segments will reflect multiple slightly differing polymerization conditions. In addition, certain quantities of a conventional random copolymer may also be formed coincident with formation of the pseudo-block copolymer of the present invention, resulting in a resin blend. If a relatively fast shuttling agent is employed, a copolymer having shorter block lengths but more uniform composition is obtained, with little formation of random copolymer. All of the blocks may be characterized as being continuously tapering, both within individual blocks and over multiple blocks. In effect, a block copolymer having multiple, generally tapering blocks or a copolymer of continuously varying composition distribution is formed. By proper selection of both catalyst and shuttling agent, copolymers containing relatively large polymer segments or blocks approximating true block copolymers or blends of the foregoing with more random copolymers can all be obtained.
A suitable composition comprising catalyst, cocatalyst, and a chain shuttling agent especially adapted for use herein can be selected by means of the following multi-step procedure:
I. One or more addition polymerizable, preferably olefin monomers are polymerized using a mixture comprising a potential catalyst and a potential chain shuttling agent. This polymerization test is desirably performed using a batch or semi-batch reactor (that is, without resupply of catalyst or shuttling agent), preferably with relatively constant monomer concentration, operating under solution polymerization conditions, typically using a molar ratio of catalyst to chain shuttling agent from 1:5 to 1:500. After forming a suitable quantity of polymer, the reaction is terminated by addition of a catalyst poison and the polymer's properties (Mw, Mn, and Mw/Mn or PDI) measured.
II. The foregoing polymerization and polymer testing are repeated for several different reaction times, providing a series of polymers having a range of yields and PDI values.
III. Catalyst/chain shuttling agent pairs demonstrating significant polymer transfer both to and from the chain shuttling agent are characterized by a polymer series wherein the minimum PDI is less than 2.0, more preferably less than 1.5, and most preferably less than 1.3. Furthermore, if chain shuttling is occurring, the Mn of the polymer will increase, preferably nearly linearly, as conversion is increased. Most preferred catalyst/shuttling agent pairs are those giving polymer Mn as a function of conversion (or polymer yield) fitting a line with a statistical precision (R2) of greater than 0.95, preferably greater than 0.99.
Steps I-III are then carried out for one or more additional pairings of potential catalysts and/or putative shuttling agents.
In addition, it is preferable that the chain shuttling agent does not reduce the catalyst activity (measured in weight of polymer produced per weight of catalyst per unit time) by more than 60 percent, more preferably such catalyst activity is not reduced by more than 20 percent, and most preferably catalyst activity of the catalyst is increased compared to the catalyst activity in the absence of a chain shuttling agent. A further consideration from a process viewpoint is that the reaction mixture should possess as low a viscosity as possible to reduce energy consumed in stirring the mixture. In this regard, a monofunctional shuttling agent is preferred to a difunctional agent which in turn is preferred to a trifunctional agent.
The foregoing test is readily adapted to rapid throughput screening techniques using automated reactors and analytic probes and to formation of polymer blocks having different distinguishing properties. For example, a number of potential chain shuttling agent candidates can be pre-identified or synthesized in situ by combination of various organometal compounds with various proton sources and the compound or reaction product added to a polymerization reaction employing an olefin polymerization catalyst composition. Several polymerizations are conducted at varying molar ratios of shuttling agent to catalyst. As a minimum requirement, suitable shuttling agents are those that produce a minimum PDI of less than 2.0 in variable yield experiments as described above, while not significantly adversely affecting catalyst activity, and preferably improving catalyst activity, as above described.
Alternatively, it is also possible to detect desirable catalyst/shuttling agent pairs by performing a series of polymerizations under standard batch reaction conditions and measuring the resulting number average molecular weights, PDI and polymer yield or production rate. Suitable shuttling agents are characterized by lowering of the resultant Mn without significant broadening of PDI or loss of activity (reduction in yield or rate).
Regardless of the method for identifying, a priori, a shuttling agent, the term is meant to refer to a compound that is capable of preparing the presently identified pseudo-block copolymers under the polymerization conditions herein disclosed.
Suitable shuttling agents for use herein include Group 1, 2, 12 or 13 metal compounds or complexes containing at least one C1-20 hydrocarbyl group, preferably hydrocarbyl substituted aluminum, gallium or zinc compounds containing from 1 to 12 carbons in each hydrocarbyl group, and reaction products thereof with a proton source. Preferred hydrocarbyl groups are alkyl groups, preferably linear or branched, C2-8 alkyl groups. Most preferred shuttling agents for use in the present invention are trialkyl aluminum and dialkyl zinc compounds, especially triethylaluminum, tri(i-propyl)aluminum, tri(1-butyl)aluminum, tri(n-hexyl)aluminum, tri(n-octyl)aluminum, triethylgallium, or diethylzinc. Additional suitable shuttling agents include the reaction product or mixture formed by combining the foregoing organometal compound, preferably a tri(C1-8) alkyl aluminum or di(C1-8)alkyl zinc compound, especially triethylaluminum, tri(i-propyl) aluminum, tri(1-butyl)aluminum, tri(n-hexyl)aluminum, tri(n-octyl)aluminum, or diethylzinc, with less than a stoichiometric quantity (relative to the number of hydrocarbyl groups) of a secondary amine or a hydroxyl compound, especially bis(trimethylsilyl)amine, t-butyl(dimethyl)siloxane, 2-hydroxymethylpyridine, di(n-pentyl)amine, 2,6-di(t-butyl)phenol, ethyl(1-naphthyl)amine, bis(2,3,6,7-dibenzo-1-azacycloheptaneamine), or 2,6-diphenylphenol. Desirably, sufficient amine or hydroxyl reagent is used such that one hydrocarbyl group remains per metal atom. The primary reaction products of the foregoing combinations most desired for use in the present invention as shuttling agents are n-octylaluminum di(bis(trimethylsilyl)amide), i-propylaluminum bis(dimethyl(t-butyl)siloxide), and n-octylaluminum di(pyridinyl-2-methoxide), i-butylaluminum bis(dimethyl(t-butyl)siloxane), i-butylaluminum bis(di(trimethylsilyl)amide), n-octylaluminum di(pyridine-2-methoxide), i-butylaluminum bis(di(n-pentyl)amide), n-octylaluminum bis(2,6-di-t-butylphenoxide), n-octylaluminum di(ethyl(1-naphthyl)amide), ethylaluminum bis(t-butyldimethylsiloxide), ethylaluminum di(bis(trimethylsilyl)amide), ethylaluminum bis(2,3,6,7-dibenzo-1-azacycloheptaneamide), n-octylaluminum bis(2,3,6,7-dibenzo-1-azacycloheptaneamide), n-octylaluminum bis(dimethyl(t-butyl)siloxide, ethylzinc (2,6-diphenylphenoxide), and ethylzinc (t-butoxide).
Preferred shuttling agents possess the highest transfer rates of polymer transfer as well as the highest transfer efficiencies (reduced incidences of chain termination). Such shuttling agents may be used in reduced concentrations and still achieve the desired degree of shuttling. In addition, such shuttling agents result in production of the shortest possible polymer block lengths. Highly desirably, chain shuttling agents with a single exchange site are employed due to the fact that the effective molecular weight of the polymer in the reactor is lowered, thereby reducing viscosity of the reaction mixture and consequently reducing operating costs.
Catalysts
Suitable catalysts for use herein include any compound or combination of compounds that is adapted for preparing polymers of the desired composition or type. Both heterogeneous and homogeneous catalysts may be employed. Examples of heterogeneous catalysts include the well known Ziegler-Natta compositions, especially Group 4 metal halides supported on Group 2 metal halides or mixed halides and alkoxides and the well known chromium or vanadium based catalysts. Preferably however, for ease of use and for production of narrow molecular weight polymer segments in solution, the catalysts for use herein are homogeneous catalysts comprising a relatively pure organometallic compound or metal complex, especially compounds or complexes based on metals selected from Groups 3-10 or the Lanthanide series of the Periodic Table of the Elements.
Metal complexes for use herein include complexes of transition metals selected from Groups 3 to 15 of the Periodic Table of the Elements containing one or more delocalized, π-bonded ligands or polyvalent Lewis base ligands. Examples include metallocene, half-metallocene, constrained geometry, and polyvalent pyridylamine, or other polychelating base complexes. The complexes are generically depicted by the formula: MKkXxZz, or a dimer thereof, wherein
M is a metal selected from Groups 3-15, preferably 3-10, more preferably 4-10, and most preferably Group 4 of the Periodic Table of the Elements;
K independently each occurrence is a group containing delocalized 7′-electrons or one or more electron pairs through which K is bound to M, said K group containing up to 50 atoms not counting hydrogen atoms, optionally two or more K groups may be joined together forming a bridged structure, and further optionally one or more K groups may be bound to Z, to X or to both Z and X;
X independently each occurrence is a monovalent, anionic moiety having up to 40 non-hydrogen atoms, optionally one or more X groups may be bonded together thereby forming a divalent or polyvalent anionic group, and, further optionally, one or more X groups and one or more Z groups may be bonded together thereby forming a moiety that is both covalently bound to M and coordinated thereto;
Z independently each occurrence is a neutral, Lewis base donor ligand of up to 50 non-hydrogen atoms containing at least one unshared electron pair through which Z is coordinated to M;
k is an integer from 0 to 3;
x is an integer from 1 to 4;
z is a number from 0 to 3; and
the sum, k+x, is equal to the formal oxidation state of M.
Suitable metal complexes include those containing from 1 to 3 π-bonded anionic or neutral ligand groups, which may be cyclic or non-cyclic delocalized π-bonded anionic ligand groups. Exemplary of such π-bonded groups are conjugated or nonconjugated, cyclic or non-cyclic diene and dienyl groups, allyl groups, boratabenzene groups, phosphole, and arene groups. By the term “π-bonded” is meant that the ligand group is bonded to the transition metal by a sharing of electrons from a partially delocalized π-bond.
Each atom in the delocalized π-bonded group may independently be substituted with a radical selected from the group consisting of hydrogen, halogen, hydrocarbyl, halohydrocarbyl, hydrocarbyl-substituted heteroatoms wherein the heteroatom is selected from Group 14-16 of the Periodic Table of the Elements, and such hydrocarbyl-substituted heteroatom radicals further substituted with a Group 15 or 16 hetero atom containing moiety. In addition two or more such radicals may together form a fused ring system, including partially or fully hydrogenated fused ring systems, or they may form a metallocycle with the metal. Included within the term “hydrocarbyl” are C1-20 straight, branched and cyclic alkyl radicals, C6-20 aromatic radicals, C7-20 alkyl-substituted aromatic radicals, and C7-20 aryl-substituted alkyl radicals. Suitable hydrocarbyl-substituted heteroatom radicals include mono-, di- and tri-substituted radicals of boron, silicon, germanium, nitrogen, phosphorus or oxygen wherein each of the hydrocarbyl groups contains from 1 to 20 carbon atoms. Examples include N,N-dimethylamino, pyrrolidinyl, trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, methyldi(t-butyl)silyl, triphenylgermyl, and trimethylgermyl groups. Examples of Group 15 or 16 hetero atom containing moieties include amino, phosphino, alkoxy, or alkylthio moieties or divalent derivatives thereof, for example, amide, phosphide, alkyleneoxy or alkylenethio groups bonded to the transition metal or Lanthanide metal, and bonded to the hydrocarbyl group, π-bonded group, or hydrocarbyl-substituted heteroatom.
Examples of suitable anionic, delocalized π-bonded groups include cyclopentadienyl, indenyl, fluorenyl, tetrahydroindenyl, tetrahydrofluorenyl, octahydrofluorenyl, pentadienyl, cyclohexadienyl, dihydroanthracenyl, hexahydroanthracenyl, decahydroanthracenyl groups, phosphole, and boratabenzyl groups, as well as inertly substituted derivatives thereof, especially C1-10 hydrocarbyl-substituted or tris(C1-10 hydrocarbyl)silyl-substituted derivatives thereof. Preferred anionic delocalized π-bonded groups are cyclopentadienyl, pentamethylcyclopentadienyl, tetramethylcyclopentadienyl, tetramethylsilylcyclopentadienyl, indenyl, 2,3-dimethylindenyl, fluorenyl, 2-methylindenyl, 2-methyl-4-phenylindenyl, tetrahydrofluorenyl, octahydrofluorenyl, 1-indacenyl, 3-pyrrolidinoinden-1-yl, 3,4-(cyclopenta(1)phenanthren-1-yl, and tetrahydroindenyl.
The boratabenzenyl ligands are anionic ligands which are boron containing analogues to benzene. They are previously known in the art having been described by G. Herberich, et al., in Organometallics, 14, 1, 471-480 (1995). Preferred boratabenzenyl ligands correspond to the formula:




wherein R1 is an inert substituent, preferably selected from the group consisting of hydrogen, hydrocarbyl, silyl, halo or germyl, said R1 having up to 20 atoms not counting hydrogen, and optionally two adjacent R1 groups may be joined together. In complexes involving divalent derivatives of such delocalized π-bonded groups one atom thereof is bonded by means of a covalent bond or a covalently bonded divalent group to another atom of the complex thereby forming a bridged system.
Phospholes are anionic ligands that are phosphorus containing analogues to a cyclopentadienyl group. They are previously known in the art having been described by WO 98/50392, and elsewhere. Preferred phosphole ligands correspond to the formula:




wherein R1 is as previously defined.
Preferred transition metal complexes for use herein correspond to the formula: MKkXxZz, or a dimer thereof, wherein:
M is a Group 4 metal;
K is a group containing delocalized π-electrons through which K is bound to M, said K group containing up to 50 atoms not counting hydrogen atoms, optionally two K groups may be joined together forming a bridged structure, and further optionally one K may be bound to X or Z;
X each occurrence is a monovalent, anionic moiety having up to 40 non-hydrogen atoms, optionally one or more X and one or more K groups are bonded together to form a metallocycle, and further optionally one or more X and one or more Z groups are bonded together thereby forming a moiety that is both covalently bound to M and coordinated thereto;
Z independently each occurrence is a neutral, Lewis base donor ligand of up to 50 non-hydrogen atoms containing at least one unshared electron pair through which Z is coordinated to M;
k is an integer from 0 to 3;
x is an integer from 1 to 4;
z is a number from 0 to 3; and
the sum, k+x, is equal to the formal oxidation state of M.
Preferred complexes include those containing either one or two K groups. The latter complexes include those containing a bridging group linking the two K groups. Preferred bridging groups are those corresponding to the formula (ER′2)e wherein E is silicon, germanium, tin, or carbon, R′ independently each occurrence is hydrogen or a group selected from silyl, hydrocarbyl, hydrocarbyloxy and combinations thereof, said R′ having up to 30 carbon or silicon atoms, and e is 1 to 8. Preferably, R′ independently each occurrence is methyl, ethyl, propyl, benzyl, tert-butyl, phenyl, methoxy, ethoxy or phenoxy.
Examples of the complexes containing two K groups are compounds corresponding to the formula:




wherein:
M is titanium, zirconium or hafnium, preferably zirconium or hafnium, in the +2 or +4 formal oxidation state;
R3 in each occurrence independently is selected from the group consisting of hydrogen, hydrocarbyl, silyl, germyl, cyano, halo and combinations thereof, said R3 having up to 20 non-hydrogen atoms, or adjacent R3 groups together form a divalent derivative (that is, a hydrocarbadiyl, siladiyl or germadiyl group) thereby forming a fused ring system, and
X′′ independently each occurrence is an anionic ligand group of up to 40 non-hydrogen atoms, or two X′′ groups together form a divalent anionic ligand group of up to 40 non-hydrogen atoms or together are a conjugated diene having from 4 to 30 non-hydrogen atoms bound by means of delocalized π-electrons to M, whereupon M is in the +2 formal oxidation state, and
R′, E and e are as previously defined.
Exemplary bridged ligands containing two π-bonded groups are: dimethylbis(cyclopentadienyl)silane, dimethylbis(tetramethylcyclopentadienyl)silane, dimethylbis(2-ethylcyclopentadien-1-yl)silane, dimethylbis(2-t-butylcyclopentadien-1-yl)silane, 2,2-bis(tetramethylcyclopentadienyl)propane, dimethylbis(inden-1-yl)silane, dimethylbis(tetrahydroinden-1-yl)silane, dimethylbis(fluoren-1-yl)silane, dimethylbis(tetrahydrofluoren-1-yl)silane, dimethylbis(2-methyl-4-phenylinden-1-yl)-silane, dimethylbis(2-methylinden-1-yl)silane, dimethyl(cyclopentadienyl)(fluoren-1-yl)silane, dimethyl(cyclopentadienyl)(octahydrofluoren-1-yl)silane, dimethyl(cyclopentadienyl)(tetrahydrofluoren-1-yl)silane, (1,1,2,2-tetramethy)-1,2-bis(cyclopentadienyl)disilane, (1,2-bis(cyclopentadienyl)ethane, and dimethyl(cyclopentadienyl)-1-(fluoren-1-yl)methane.
Preferred X′′ groups are selected from hydride, hydrocarbyl, silyl, germyl, halohydrocarbyl, halosilyl, silylhydrocarbyl and aminohydrocarbyl groups, or two X′′ groups together form a divalent derivative of a conjugated diene or else together they form a neutral, α-bonded, conjugated diene. Most preferred X′′ groups are C1-20 hydrocarbyl groups.
Examples of metal complexes of the foregoing formula suitable for use in the present invention include:

    bis(cyclopentadienyl)zirconiumdimethyl,
    bis(cyclopentadienyl)zirconium dibenzyl,
    bis(cyclopentadienyl)zirconium methyl benzyl,
    bis(cyclopentadienyl)zirconium methyl phenyl,
    bis(cyclopentadienyl)zirconiumdiphenyl,
    bis(cyclopentadienyl)titanium-allyl,
    bis(cyclopentadienyl)zirconiummethylmethoxide,
    bis(cyclopentadienyl)zirconiummethylchloride,
    bis(pentamethylcyclopentadienyl)zirconiumdimethyl,
    bis(pentamethylcyclopentadienyl)titaniumdimethyl,
    bis(indenyl)zirconiumdimethyl,
    indenylfluorenylzirconiumdimethyl,
    bis(indenyl)zirconiummethyl(2-(dimethylamino)benzyl),
    bis(indenyl)zirconiummethyltrimethylsilyl,
    bis(tetrahydroindenyl)zirconiummethyltrimethylsilyl,
    bis(pentamethylcyclopentadienyl)zirconiummethylbenzyl,
    bis(pentamethylcyclopentadienyl)zirconiumdibenzyl,
    bis(pentamethylcyclopentadienyl)zirconiummethylmethoxide,
    bis(pentamethylcyclopentadienyl)zirconiummethylchloride,
    bis(methylethylcyclopentadienyl)zirconiumdimethyl,
    bis(butylcyclopentadienyl)zirconiumdibenzyl,
    bis(t-butylcyclopentadienyl)zirconiumdimethyl,
    bis(ethyltetramethylcyclopentadienyl)zirconiumdimethyl,
    bis(methylpropylcyclopentadienyl)zirconiumdibenzyl,
    bis(trimethylsilylcyclopentadienyl)zirconiumdibenzyl,
    dimethylsilylbis(cyclopentadienyl)zirconiumdimethyl, dimethylsilylbis(tetramethylcyclopentadienyl)titanium (III) allyl
    dimethylsilylbis(t-butylcyclopentadienyl)zirconiumdichloride,
    dimethylsilylbis(n-butylcyclopentadienyl)zirconiumdichloride,
    (methylenebis(tetramethylcyclopentadienyl)titanium(III) 2-(dimethylamino)benzyl,
    (methylenebis(n-butylcyclopentadienyl)titanium(III) 2-(dimethylamino)benzyl,
    dimethylsilylbis(indenyl)zirconiumbenzylchloride,
    dimethylsilylbis(2-methylindenyl)zirconiumdimethyl,
    dimethylsilylbis(2-methyl-4-phenylindenyl)zirconiumdimethyl,
    dimethylsilylbis(2-methylindenyl)zirconium-1,4-diphenyl-1,3-butadiene,
    dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium (II) 1,4-diphenyl-1,3-butadiene,
    dimethylsilylbis(tetrahydroindenyl)zirconium(II) 1,4-diphenyl-1,3-butadiene,
    dimethylsilylbis(tetramethylcyclopentadienyl)zirconium dimethyl
    dimethylsilylbis(fluorenyl)zirconiumdimethyl,
    dimethylsilyl-bis(tetrahydrofluorenyl)zirconium bis(trimethylsilyl),
    (isopropylidene)(cyclopentadienyl)(fluorenyl)zirconiumdibenzyl, and
    dimethylsilyl(tetramethylcyclopentadienyl)(fluorenyl)zirconium dimethyl.


A further class of metal complexes utilized in the present invention corresponds to the preceding formula: MKZzXx, or a dimer thereof, wherein M, K, X, x and z are as previously defined, and Z is a substituent of up to 50 non-hydrogen atoms that together with K forms a metallocycle with M.
Preferred Z substituents include groups containing up to 30 non-hydrogen atoms comprising at least one atom that is oxygen, sulfur, boron or a member of Group 14 of the Periodic Table of the Elements directly attached to K, and a different atom, selected from the group consisting of nitrogen, phosphorus, oxygen or sulfur that is covalently bonded to M.
More specifically this class of Group 4 metal complexes used according to the present invention includes “constrained geometry catalysts” corresponding to the formula:




wherein:
M is titanium or zirconium, preferably titanium in the +2, +3, or +4 formal oxidation state;
K1 is a delocalized, π-bonded ligand group optionally substituted with from 1 to 5 R2 groups,
R2 in each occurrence independently is selected from the group consisting of hydrogen, hydrocarbyl, silyl, germyl, cyano, halo and combinations thereof, said R2 having up to 20 non-hydrogen atoms, or adjacent R2 groups together form a divalent derivative (that is, a hydrocarbadiyl, siladiyl or germadiyl group) thereby forming a fused ring system,
each X is a halo, hydrocarbyl, hydrocarbyloxy or silyl group, said group having up to 20 non-hydrogen atoms, or two X groups together form a neutral C5-30 conjugated diene or a divalent derivative thereof;
x is 1 or 2;
Y is —O—, —S—, —NR′—, —PR′—; and
X1 is SiR′2, CR′2, SiR′2SiR′2, CR′2CR′2, CR′═CR′, CR′2SiR′2, or GeR′2, wherein
R′ independently each occurrence is hydrogen or a group selected from silyl, hydrocarbyl, hydrocarbyloxy and combinations thereof, said R′ having up to 30 carbon or silicon atoms.
Specific examples of the foregoing constrained geometry metal complexes include compounds corresponding to the formula:




wherein,

Ar is an aryl group of from 6 to 30 atoms not counting hydrogen;
R4 independently each occurrence is hydrogen, Ar, or a group other than Ar selected from hydrocarbyl, trihydrocarbylsilyl, trihydrocarbylgermyl, halide, hydrocarbyloxy, trihydrocarbylsiloxy, bis(trihydrocarbylsilyl)amino, di(hydrocarbyl)amino, hydrocarbadiylamino, hydrocarbylimino, di(hydrocarbyl)phosphino, hydrocarbadiylphosphino, hydrocarbylsulfido, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, trihydrocarbylsilyl-substituted hydrocarbyl, trihydrocarbylsiloxy-substituted hydrocarbyl, bis(trihydrocarbylsilyl)amino-substituted hydrocarbyl, di(hydrocarbyl)amino-substituted hydrocarbyl, hydrocarbyleneamino-substituted hydrocarbyl, di(hydrocarbyl)phosphino-substituted hydrocarbyl, hydrocarbylenephosphino-substituted hydrocarbyl, or hydrocarbylsulfido-substituted hydrocarbyl, said R group having up to 40 atoms not counting hydrogen atoms, and optionally two adjacent R4 groups may be joined together forming a polycyclic fused ring group;
M is titanium;
X1 is SiR62, CR62, SiR62SiR62, CR62CR62, CR6═CR6, CR62SiR62, BR6, BR6L′′, or GeR62;
Y is —O—, —S—, —NR5—, —PR5—; —NR2, or —PR52;
R5, independently each occurrence, is hydrocarbyl, trihydrocarbylsilyl, or trihydrocarbylsilylhydrocarbyl, said R5 having up to 20 atoms other than hydrogen, and optionally two R5 groups or R5 together with Y or Z form a ring system;
R6, independently each occurrence, is hydrogen, or a member selected from hydrocarbyl, hydrocarbyloxy, silyl, halogenated alkyl, halogenated aryl, —NR52, and combinations thereof, said R6 having up to 20 non-hydrogen atoms, and optionally, two R1 groups or R1 together with Z forms a ring system;
Z is a neutral diene or a monodentate or polydentate Lewis base optionally bonded to R5, R6, or X;
X is hydrogen, a monovalent anionic ligand group having up to 60 atoms not counting hydrogen, or two X groups are joined together thereby forming a divalent ligand group;
x is 1 or 2; and
z is 0, 1 or 2.
Preferred examples of the foregoing metal complexes are substituted at both the 3- and 4-positions of a cyclopentadienyl or indenyl group with an Ar group.
Examples of the foregoing metal complexes include:

    (3-phenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-phenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-phenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,3-diphenyl-1,3-butadiene;
    (3-(pyrrol-1-yl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-(pyrrol-1-yl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-(pyrrol-1-yl)cyclopentadien-1-yl))dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (3-(1-methylpyrrol-3-yl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-(1-methylpyrrol-3-yl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-(1-methylpyrrol-3-yl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (3,4-diphenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3,4-diphenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3,4-diphenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,3-pentadiene;
    (3-(3-N,N-dimethylamino)phenyl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-(3-N,N-dimethylamino)phenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-(3-N,N-dimethylamino)phenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (3-(4-methoxyphenyl)-4-methylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-(4-methoxyphenyl)-4-phenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-4-methoxyphenyl)-4-phenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (3-phenyl-4-methoxycyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-phenyl-4-methoxycyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-phenyl-4-methoxycyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (3-phenyl-4-(N,N-dimethylamino)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-phenyl-4-(N,N-dimethylamino)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-phenyl-4-(N,N-dimethylamino)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    2-methyl-(3,4-di(4-methylphenyl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    2-methyl-(3,4-di(4-methylphenyl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    2-methyl-(3,4-di(4-methylphenyl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    ((2,3-diphenyl)-4-(N,N-dimethylamino)cyclopentadien-1-yl)dimethyl(t-butylamido)silane titanium dichloride,
    ((2,3-diphenyl)-4-(N,N-dimethylamino)cyclopentadien-1-yl)dimethyl(t-butylamido)silane titanium dimethyl,
    ((2,3-diphenyl)-4-(N,N-dimethylamino)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (2,3,4-triphenyl-5-methylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (2,3,4-triphenyl-5-methylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (2,3,4-triphenyl-5-methylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (3-phenyl-4-methoxycyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (3-phenyl-4-methoxycyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (3-phenyl-4-methoxycyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (2,3-diphenyl-4-(n-butyl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (2,3-diphenyl-4-(n-butyl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl,
    (2,3-diphenyl-4-(n-butyl)cyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene;
    (2,3,4,5-tetraphenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dichloride,
    (2,3,4,5-tetraphenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium dimethyl, and
    (2,3,4,5-tetraphenylcyclopentadien-1-yl)dimethyl(t-butylamido)silanetitanium (II) 1,4-diphenyl-1,3-butadiene.


Additional examples of suitable metal complexes for use herein are polycyclic complexes corresponding to the formula:




where M is titanium in the +2, +3 or +4 formal oxidation state;
R7 independently each occurrence is hydride, hydrocarbyl, silyl, germyl, halide, hydrocarbyloxy, hydrocarbylsiloxy, hydrocarbylsilylamino, di(hydrocarbyl)amino, hydrocarbyleneamino, di(hydrocarbyl)phosphino, hydrocarbylene-phosphino, hydrocarbylsulfido, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, silyl-substituted hydrocarbyl, hydrocarbylsiloxy-substituted hydrocarbyl, hydrocarbylsilylamino-substituted hydrocarbyl, di(hydrocarbyl)amino-substituted hydrocarbyl, hydrocarbyleneamino-substituted hydrocarbyl, di(hydrocarbyl)phosphino-substituted hydrocarbyl, hydrocarbylene-phosphino-substituted hydrocarbyl, or hydrocarbylsulfido-substituted hydrocarbyl, said R7 group having up to 40 atoms not counting hydrogen, and optionally two or more of the foregoing groups may together form a divalent derivative;
R8 is a divalent hydrocarbylene- or substituted hydrocarbylene group forming a fused system with the remainder of the metal complex, said R8 containing from 1 to 30 atoms not counting hydrogen;
Xa is a divalent moiety, or a moiety comprising one σ-bond and a neutral two electron pair able to form a coordinate-covalent bond to M, said Xa comprising boron, or a member of Group 14 of the Periodic Table of the Elements, and also comprising nitrogen, phosphorus, sulfur or oxygen;
X is a monovalent anionic ligand group having up to 60 atoms exclusive of the class of ligands that are cyclic, delocalized, π-bound ligand groups and optionally two X groups together form a divalent ligand group;
Z independently each occurrence is a neutral ligating compound having up to 20 atoms;
x is 0, 1 or 2; and
z is zero or 1.
Preferred examples of such complexes are 3-phenyl-substituted s-indecenyl complexes corresponding to the formula:




2,3-dimethyl-substituted s-indecenyl complexes corresponding to the formulas:




or 2-methyl-substituted s-indecenyl complexes corresponding to the formula:




Additional examples of metal complexes that are usefully employed according to the present invention include those of the formula:




Specific metal complexes include:

    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,4-diphenyl-1,3-butadiene,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,3-pentadiene,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 2-(N,N-dimethylamino)benzyl,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dichloride,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dimethyl,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dibenzyl,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,4-diphenyl-1,3-butadiene,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,3-pentadiene,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (III) 2-(N,N-dimethylamino)benzyl,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dichloride,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dimethyl,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-1-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dibenzyl,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,4-diphenyl-1,3-butadiene,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,3-pentadiene,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (III) 2-(N,N-dimethylamino)benzyl,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dichloride,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dimethyl,
    (8-methylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dibenzyl,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,4-diphenyl-1,3-butadiene,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (II) 1,3-pentadiene,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (III) 2-(N,N-dimethylamino)benzyl,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dichloride,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dimethyl,
    (8-difluoromethylene-1,8-dihydrodibenzo[e,h]azulen-2-yl)-N-(1,1-dimethylethyl)dimethylsilanamide titanium (IV) dibenzyl, and mixtures thereof, especially mixtures of positional isomers.


Further illustrative examples of metal complexes for use according to the present invention correspond to the formula:




where M is titanium in the +2, +3 or +4 formal oxidation state;
T is —NR9— or —O—;
R9 is hydrocarbyl, silyl, germyl, dihydrocarbylboryl, or halohydrocarbyl or up to 10 atoms not counting hydrogen;
R10 independently each occurrence is hydrogen, hydrocarbyl, trihydrocarbylsilyl, trihydrocarbylsilylhydrocarbyl, germyl, halide, hydrocarbyloxy, hydrocarbylsiloxy, hydrocarbylsilylamino, di(hydrocarbyl)amino, hydrocarbyleneamino, di(hydrocarbyl)phosphino, hydrocarbylene-phosphino, hydrocarbylsulfido, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, silyl-substituted hydrocarbyl, hydrocarbylsiloxy-substituted hydrocarbyl, hydrocarbylsilylamino-substituted hydrocarbyl, di(hydrocarbyl)amino-substituted hydrocarbyl, hydrocarbyleneamino-substituted hydrocarbyl, di(hydrocarbyl)phosphino-substituted hydrocarbyl, hydrocarbylenephosphino-substituted hydrocarbyl, or hydrocarbylsulfido-substituted hydrocarbyl, said R10 group having up to 40 atoms not counting hydrogen atoms, and optionally two or more of the foregoing adjacent R10 groups may together form a divalent derivative thereby forming a saturated or unsaturated fused ring;
Xa is a divalent moiety lacking in delocalized n-electrons, or such a moiety comprising one σ-bond and a neutral two electron pair able to form a coordinate-covalent bond to M, said X′ comprising boron, or a member of Group 14 of the Periodic Table of the Elements, and also comprising nitrogen, phosphorus, sulfur or oxygen;
X is a monovalent anionic ligand group having up to 60 atoms exclusive of the class of ligands that are cyclic ligand groups bound to M through delocalized π-electrons or two X groups together are a divalent anionic ligand group;
Z independently each occurrence is a neutral ligating compound having up to 20 atoms;
x is 0, 1, 2, or 3; and
z is 0 or 1.
Highly preferably T is ═N(CH3), X is halo or hydrocarbyl, x is 2, X′ is dimethylsilane, z is 0, and R10 each occurrence is hydrogen, a hydrocarbyl, hydrocarbyloxy, dihydrocarbylamino, hydrocarbyleneamino, dihydrocarbylamino-substituted hydrocarbyl group, or hydrocarbyleneamino-substituted hydrocarbyl group of up to 20 atoms not counting hydrogen, and optionally two R10 groups may be joined together.
Illustrative metal complexes of the foregoing formula that may be employed in the practice of the present invention further include the following compounds:

    (t-butylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (t-butylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,3-pentadiene,
    (t-butylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (III) 2-(N,N-dimethylamino)benzyl,
    (t-butylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dichloride,
    (t-butylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dimethyl,
    (t-butylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dibenzyl,
    (t-butylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) bis(trimethylsilyl),
    (cyclohexylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (cyclohexylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,3-pentadiene,
    (cyclohexylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (III) 2-(N,N-dimethylamino)benzyl,
    (cyclohexylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dichloride,
    (cyclohexylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dimethyl,
    (cyclohexylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dibenzyl,
    (cyclohexylamido)dimethyl-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) bis(trimethylsilyl),
    (t-butylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (t-butylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,3-pentadiene,
    (t-butylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (III) 2-(N,N-dimethylamino)benzyl,
    (t-butylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dichloride,
    (t-butylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dimethyl,
    (t-butylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dibenzyl,
    (t-butylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) bis(trimethylsilyl),
    (cyclohexylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (cyclohexylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (II) 1,3-pentadiene,
    (cyclohexylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (III) 2-(N,N-dimethylamino)benzyl,
    (cyclohexylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dichloride,
    (cyclohexylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dimethyl,
    (cyclohexylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) dibenzyl; and
    (cyclohexylamido)di(p-methylphenyl)-[6,7]benzo-[4,5:2′,3′](1-methylisoindol)-(3H)-indene-2-yl)silanetitanium (IV) bis(trimethylsilyl).


Illustrative Group 4 metal complexes that may be employed in the practice of the present invention further include:

    (tert-butylamido)(1,1-dimethyl-2,3,4,9,10-η-1,4,5,6,7,8-hexahydronaphthalenyl)dimethylsilanetitaniumdimethyl,
    (tert-butylamido)(1,1,2,3-tetramethyl-2,3,4,9,10-η-1,4,5,6,7,8-hexahydronaphthalenyl)dimethylsilanetitaniumdimethyl,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl) dimethylsilanetitanium dibenzyl,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium dimethyl,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)-1,2-ethanediyltitanium dimethyl,
    (tert-butylamido)(tetramethyl-η5-indenyl)dimethylsilanetitanium dimethyl,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethlylsilane titanium (III) 2-(dimethylamino)benzyl;
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium (III) allyl,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium (III) 2,4-dimethylpentadienyl,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium (II) 1,3-pentadiene,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (II) 2,4-hexadiene,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (IV) 2,3-dimethyl-1,3-butadiene,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (IV) isoprene,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (IV) 1,3-butadiene,
    (tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (IV) 2,3-dimethyl-1,3-butadiene,
    (tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (IV) isoprene
    (tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (IV) dimethyl
    (tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (IV) dibenzyl
    (tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (IV) 1,3-butadiene,
    (tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (II) 1,3-pentadiene,
    (tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (II) 1,3-pentadiene,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (IV) dimethyl,
    (tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (IV) dibenzyl,
    (tert-butylamido)(2-methyl-4-phenylindenyl)dimethylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    (tert-butylamido)(2-methyl-4-phenylindenyl)dimethylsilanetitanium (II) 1,3-pentadiene,
    (tert-butylamido)(2-methyl-4-phenylindenyl)dimethylsilanetitanium (II) 2,4-hexadiene,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethyl-silanetitanium (IV) 1,3-butadiene,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium (IV) 2,3-dimethyl-1,3-butadiene,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium (IV) isoprene,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethyl-silanetitanium (II) 1,4-dibenzyl-1,3-butadiene,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilanetitanium (II) 2,4-hexadiene,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethyl-silanetitanium (II) 3-methyl-1,3-pentadiene,
    (tert-butylamido)(2,4-dimethylpentadien-3-yl)dimethylsilanetitaniumdimethyl,
    (tert-butylamido)(6,6-dimethylcyclohexadienyl)dimethylsilanetitaniumdimethyl,
    (tert-butylamido)(1,1-dimethyl-2,3,4,9,10-η-1,4,5,6,7,8-hexahydronaphthalen-4-yl)dimethylsilanetitaniumdimethyl,
    (tert-butylamido)(1,1,2,3-tetramethyl-2,3,4,9,10-η-1,4,5,6,7,8-hexahydronaphthalen-4-yl)dimethylsilanetitaniumdimethyl
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl methylphenylsilanetitanium (IV) dimethyl,
    (tert-butylamido)(tetramethyl-η5-cyclopentadienyl methylphenylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
    1-(tert-butylamido)-2-(tetramethyl-η5-cyclopentadienyl)ethanediyltitanium (IV) dimethyl, and
    1-(tert-butylamido)-2-(tetramethyl-η5-cyclopentadienyl)ethanediyl-titanium (II) 1,4-diphenyl-1,3-butadiene.


Other delocalized, π-bonded complexes, especially those containing other Group 4 metals, will, of course, be apparent to those skilled in the art, and are disclosed among other places in: WO 03/78480, WO 03/78483, WO 02/92610, WO 02/02577, US 2003/0004286 and U.S. Pat. Nos. 6,515,155, 6,555,634, 6,150,297, 6,034,022, 6,268,444, 6,015,868, 5,866,704, and 5,470,993.
Additional examples of metal complexes that are usefully employed herein include polyvalent Lewis base compounds corresponding to the formula:




wherein Tb is a bridging group, preferably containing 2 or more atoms other than hydrogen,
Xb and Yb are each independently selected from the group consisting of nitrogen, sulfur, oxygen and phosphorus; more preferably both Xb and Yb are nitrogen,
Rb and Rb′ independently each occurrence are hydrogen or C1-50 hydrocarbyl groups optionally containing one or more heteroatoms or inertly substituted derivative thereof. Non-limiting examples of suitable Rb and Rb′ groups include alkyl, alkenyl, aryl, aralkyl, (poly)alkylaryl and cycloalkyl groups, as well as nitrogen, phosphorus, oxygen and halogen substituted derivatives thereof. Specific examples of suitable Rb and Rb′ groups include methyl, ethyl, isopropyl, octyl, phenyl, 2,6-dimethylphenyl, 2,6-di(isopropyl)phenyl, 2,4,6-trimethylphenyl, pentafluorophenyl, 3,5-trifluoromethylphenyl, and benzyl;
g is 0 or 1;
Mb is a metallic element selected from Groups 3 to 15, or the Lanthanide series of the Periodic Table of the Elements. Preferably, Mb is a Group 3-13 metal, more preferably Mb is a Group 4-10 metal;
Lb is a monovalent, divalent, or trivalent anionic ligand containing from 1 to 50 atoms, not counting hydrogen. Examples of suitable Lb groups include halide; hydride; hydrocarbyl, hydrocarbyloxy; di(hydrocarbyl)amido, hydrocarbyleneamido, di(hydrocarbyl)phosphido; hydrocarbylsulfido; hydrocarbyloxy, tri(hydrocarbylsilyl)alkyl; and carboxylates. More preferred Lb groups are C1-20 alkyl, C7-20 aralkyl, and chloride;
h is an integer from 1 to 6, preferably from 1 to 4, more preferably from 1 to 3, and j is 1 or 2, with the value h×j selected to provide charge balance;
Zb is a neutral ligand group coordinated to Mb, and containing up to 50 atoms not counting hydrogen Preferred Zb groups include aliphatic and aromatic amines, phosphines, and ethers, alkenes, alkadienes, and inertly substituted derivatives thereof. Suitable inert substituents include halogen, alkoxy, aryloxy, alkoxycarbonyl, aryloxycarbonyl, di(hydrocarbyl)amine, tri(hydrocarbyl)silyl, and nitrile groups. Preferred Zb groups include triphenylphosphine, tetrahydrofuran, pyridine, and 1,4-diphenylbutadiene;
f is an integer from 1 to 3;
two or three of Tb, Rb and Rb′ may be joined together to form a single or multiple ring structure;
h is an integer from 1 to 6, preferably from 1 to 4, more preferably from 1 to 3;
 indicates any form of electronic interaction comprising a net coulombic attraction, especially coordinate or covalent bonds, including multiple bonds;
arrows signify coordinate bonds; and
dotted lines indicate optional double bonds.
In one embodiment, it is preferred that Rb have relatively low steric hindrance with respect to Xb. In this embodiment, most preferred Rb groups are straight chain alkyl groups, straight chain alkenyl groups, branched chain alkyl groups wherein the closest branching point is at least 3 atoms removed from Xb, and halo, dihydrocarbylamino, alkoxy or trihydrocarbylsilyl substituted derivatives thereof. Highly preferred Rb groups in this embodiment are C1-8 straight chain alkyl groups.
At the same time, in this embodiment Rb′ preferably has relatively high steric hindrance with respect to Yb. Non-limiting examples of suitable Rb′ groups for this embodiment include alkyl or alkenyl groups containing one or more secondary or tertiary carbon centers, cycloalkyl, aryl, alkaryl, aliphatic or aromatic heterocyclic groups, organic or inorganic oligomeric, polymeric or cyclic groups, and halo, dihydrocarbylamino, alkoxy or trihydrocarbylsilyl substituted derivatives thereof. Preferred Rb′ groups in this embodiment contain from 3 to 40, more preferably from 3 to 30, and most preferably from 4 to 20 atoms not counting hydrogen and are branched or cyclic.
Examples of preferred Tb groups are structures corresponding to the following formulas:




wherein

Each Rd is C1-10 hydrocarbyl group, preferably methyl, ethyl, n-propyl, i-propyl, t-butyl, phenyl, 2,6-dimethylphenyl, benzyl, or tolyl. Each Re is C1-10 hydrocarbyl, preferably methyl, ethyl, n-propyl, i-propyl, t-butyl, phenyl, 2,6-dimethylphenyl, benzyl, or tolyl. In addition, two or more Rd or Re groups, or mixtures of Rd and Re groups may together form a polyvalent derivative of a hydrocarbyl group, such as, 1,4-butylene, 1,5-pentylene, or a multicyclic, fused ring, polyvalent hydrocarbyl- or heterohydrocarbyl-group, such as naphthalene-1,8-diyl.
Preferred examples of the foregoing polyvalent Lewis base complexes include:




wherein Rd′ each occurrence is independently selected from the group consisting of hydrogen and C1-50 hydrocarbyl groups optionally containing one or more heteroatoms, or inertly substituted derivative thereof, or further optionally, two adjacent Rd′ groups may together form a divalent bridging group;
d′ is 4;
Mb′ is a group 4 metal, preferably titanium or hafnium or a Group 10 metal, preferably Ni or Pd;
Lb′ is a monovalent ligand of up to 50 atoms not counting hydrogen, preferably halide or hydrocarbyl, or two Lb′ groups together are a divalent or neutral ligand group, preferably a C2-50 hydrocarbylene, hydrocarbadiyl or diene group.
The polyvalent Lewis base complexes for use in the present invention especially include Group 4 metal derivatives, especially hafnium derivatives of hydrocarbylamine substituted heteroaryl compounds corresponding to the formula:




wherein:
R11 is selected from alkyl, cycloalkyl, heteroalkyl, cycloheteroalkyl, aryl, and inertly substituted derivatives thereof containing from 1 to 30 atoms not counting hydrogen or a divalent derivative thereof;
T1 is a divalent bridging group of from 1 to 41 atoms other than hydrogen, preferably 1 to 20 atoms other than hydrogen, and most preferably a mono- or di-C1-20 hydrocarbyl substituted methylene or silane group; and
R12 is a C5-20 heteroaryl group containing Lewis base functionality, especially a pyridin-2-yl- or substituted pyridin-2-yl group or a divalent derivative thereof;
M1 is a Group 4 metal, preferably hafnium;
X1 is an anionic, neutral or dianionic ligand group;
x′ is a number from 0 to 5 indicating the number of such X1 groups; and
bonds, optional bonds and electron donative interactions are represented by lines, dotted lines and arrows respectively.
Preferred complexes are those wherein ligand formation results from hydrogen elimination from the amine group and optionally from the loss of one or more additional groups, especially from R12. In addition, electron donation from the Lewis base functionality, preferably an electron pair, provides additional stability to the metal center. Preferred metal complexes correspond to the formula:




wherein

M1, X1, x′, R11 and T1 are as previously defined,
R13, R14, R15 and R16 are hydrogen, halo, or an alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aryl, or silyl group of up to 20 atoms not counting hydrogen, or adjacent R13, R14, R15 or R16 groups may be joined together thereby forming fused ring derivatives, and
bonds, optional bonds and electron pair donative interactions are represented by lines, dotted lines and arrows respectively.
More preferred examples of the foregoing metal complexes correspond to the formula:




wherein

M1, X1, and x′ are as previously defined,
R13, R14, R15 and R16 are as previously defined, preferably R13, R14, and R15 are hydrogen, or C1-4 alkyl, and R16 is C6-20 aryl, most preferably naphthalenyl;
Ra independently each occurrence is C1-4 alkyl, and a is 1-5, most preferably Ra in two ortho-positions to the nitrogen is isopropyl or t-butyl;
R17 and R18 independently each occurrence are hydrogen, halogen, or a C1-20 alkyl or aryl group, most preferably one of R17 and R18 is hydrogen and the other is a C6-20 aryl group, especially 2-isopropyl, phenyl or a fused polycyclic aryl group, most preferably an anthracenyl group, and
bonds, optional bonds and electron pair donative interactions are represented by lines, dotted lines and arrows respectively.
Highly preferred metal complexes for use herein correspond to the formula:




wherein X1 each occurrence is halide, N,N-dimethylamido, or C1-4 alkyl, and preferably each occurrence X1 is methyl;
Rf independently each occurrence is hydrogen, halogen, C1-20 alkyl, or C6-20 aryl, or two adjacent Rf groups are joined together thereby forming a ring, and f is 1-5; and
Rc independently each occurrence is hydrogen, halogen, C1-20 alkyl, or C6-20 aryl, or two adjacent Re groups are joined together thereby forming a ring, and c is 1-5.
Most highly preferred examples of metal complexes for use according to the present invention are complexes of the following formulas:




wherein Rx is C1-4 alkyl or cycloalkyl, preferably methyl, isopropyl, t-butyl or cyclohexyl; and
X1 each occurrence is halide, N,N-dimethylamido, or C1-4 alkyl, preferably methyl.
Examples of metal complexes usefully employed according to the present invention include:

    [N-(2,6-di(1-methylethyl)phenyl)amido)(o-tolyl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dimethyl;
    [N-(2,6-di(1-methylethyl)phenyl)amido)(o-tolyl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium di(N,N-dimethylamido);
    [N-(2,6-di(1-methylethyl)phenyl)amido)(o-tolyl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dichloride;
    [N-(2,6-di(1-methylethyl)phenyl)amido)(2-isopropylphenyl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dimethyl;
    [N-(2,6-di(1-methylethyl)phenyl)amido)(2-isopropylphenyl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium di(N,N-dimethylamido);
    [N-(2,6-di(1-methylethyl)phenyl)amido)(2-isopropylphenyl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dichloride;
    [N-(2,6-di(1-methylethyl)phenyl)amido)(phenanthren-5-yl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dimethyl;
    [N-(2,6-di(1-methylethyl)phenyl)amido)(phenanthren-5-yl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium di(N,N-dimethylamido); and
    [N-(2,6-di(1-methylethyl)phenyl)amido)(phenanthren-5-yl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dichloride.


Under the reaction conditions used to prepare the metal complexes used in the present invention, the hydrogen of the 2-position of the α-naphthalene group substituted at the 6-position of the pyridin-2-yl group is subject to elimination, thereby uniquely forming metal complexes wherein the metal is covalently bonded to both the resulting amide group and to the 2-position of the α-naphthalenyl group, as well as stabilized by coordination to the pyridinyl nitrogen atom through the electron pair of the nitrogen atom.
Additional suitable metal complexes of polyvalent Lewis bases for use herein include compounds corresponding to the formula:




where:

R20 is an aromatic or inertly substituted aromatic group containing from 5 to 20 atoms not counting hydrogen, or a polyvalent derivative thereof;
T3 is a hydrocarbylene or silane group having from 1 to 20 atoms not counting hydrogen, or an inertly substituted derivative thereof;
M3 is a Group 4 metal, preferably zirconium or hafnium;
G is an anionic, neutral or dianionic ligand group; preferably a halide, hydrocarbyl or dihydrocarbylamide group having up to 20 atoms not counting hydrogen;
g is a number from 1 to 5 indicating the number of such G groups; and
bonds and electron donative interactions are represented by lines and arrows respectively.
Preferably, such complexes correspond to the formula:




wherein:

T3 is a divalent bridging group of from 2 to 20 atoms not counting hydrogen, preferably a substituted or unsubstituted, C3-6 alkylene group; and
Ar2 independently each occurrence is an arylene or an alkyl- or aryl-substituted arylene group of from 6 to 20 atoms not counting hydrogen;
M3 is a Group 4 metal, preferably hafnium or zirconium;
G independently each occurrence is an anionic, neutral or dianionic ligand group;
g is a number from 1 to 5 indicating the number of such X groups; and
electron donative interactions are represented by arrows.
Preferred examples of metal complexes of foregoing formula include the following compounds:




where M3 is Hf or Zr;
Ar4 is C6-20 aryl or inertly substituted derivatives thereof, especially 3,5-di(isopropyl)phenyl, 3,5-di(isobutyl)phenyl, dibenzo-1H-pyrrole-1-yl, or anthracen-5-yl, and
T4 independently each occurrence comprises a C3-6 alkylene group, a C3-6 cycloalkylene group, or an inertly substituted derivative thereof;
R21 independently each occurrence is hydrogen, halo, hydrocarbyl, trihydrocarbylsilyl, or trihydrocarbylsilylhydrocarbyl of up to 50 atoms not counting hydrogen; and
G, independently each occurrence is halo or a hydrocarbyl or trihydrocarbylsilyl group of up to 20 atoms not counting hydrogen, or 2 G groups together are a divalent derivative of the foregoing hydrocarbyl or trihydrocarbylsilyl groups.
Especially preferred are compounds of the formula:




wherein Ar4 is 3,5-di(isopropyl)phenyl, 3,5-di(isobutyl)phenyl, dibenzo-1H-pyrrole-1-yl, or anthracen-5-yl,
R21 is hydrogen, halo, or C1-4 alkyl, especially methyl
T4 is propan-1,3-diyl or butan-1,4-diyl, and
G is chloro, methyl or benzyl.
A most highly preferred metal complex of the foregoing formula is:




The foregoing polyvalent Lewis base complexes are conveniently prepared by standard metallation and ligand exchange procedures involving a source of the Group 4 metal and the neutral polyfunctional ligand source. In addition, the complexes may also be prepared by means of an amide elimination and hydrocarbylation process starting from the corresponding Group 4 metal tetraamide and a hydrocarbylating agent, such as trimethylaluminum. Other techniques may be used as well. These complexes are known from the disclosures of, among others, U.S. Pat. Nos. 6,320,005, 6,103,657, WO 02/38628, WO 03/40195, and US04/0220050.
Catalysts having high comonomer incorporation properties are also known to reincorporate in situ prepared long chain olefins resulting incidentally during the polymerization through β-hydride elimination and chain termination of growing polymer, or other process. The concentration of such long chain olefins is particularly enhanced by use of continuous solution polymerization conditions at high conversions, especially ethylene conversions of 95 percent or greater, more preferably at ethylene conversions of 97 percent or greater. Under such conditions a small but detectable quantity of olefin terminated polymer may be reincorporated into a growing polymer chain, resulting in the formation of long chain branches, that is, branches of a carbon length greater than would result from other deliberately added comonomer. Moreover, such chains reflect the presence of other comonomers present in the reaction mixture. That is, the chains may include short chain or long chain branching as well, depending on the comonomer composition of the reaction mixture.
Additional suitable metal compounds for use herein include Group 4-10 metal derivatives corresponding to the formula:




wherein

    
    
        M2 is a metal of Groups 4-10 of the Periodic Table of the elements, preferably Group 4 metals, Ni(II) or Pd(II), most preferably zirconium;
        T2 is a nitrogen, oxygen or phosphorus containing group;
        X2 is halo, hydrocarbyl, or hydrocarbyloxy;
        t is one or two;
        x′′ is a number selected to provide charge balance;
        and T2 and N are linked by a bridging ligand.
    
    


Such catalysts have been previously disclosed in J. Am. Chem. Soc., 118, 267-268 (1996), J. Am. Chem. Soc., 117, 6414-6415 (1995), and Organometallics, 16, 1514-1516, (1997), among other disclosures.
Preferred examples of the foregoing metal complexes are aromatic diimine or aromatic dioxyimine complexes of Group 4 metals, especially zirconium, corresponding to the formula:




wherein;
M2, X2 and T2 are as previously defined;
Rd independently each occurrence is hydrogen, halogen, or Re; and
Re independently each occurrence is C1-20 hydrocarbyl or a heteroatom-, especially a F, N, S or P-substituted derivative thereof, more preferably C1-10 hydrocarbyl or a F or N substituted derivative thereof, most preferably alkyl, dialkylaminoalkyl, pyrrolyl, piperidenyl, perfluorophenyl, cycloalkyl, (poly)alkylaryl, or aralkyl.
Most preferred examples of the foregoing metal complexes are aromatic dioxyimine complexes of zirconium, corresponding to the formula:




wherein;
X2 is as previously defined, preferably C1-10 hydrocarbyl, most preferably methyl or benzyl; and
Re′ is methyl, isopropyl, t-butyl, cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 2,4-dimethylcyclohexyl, 2-pyrrolyl, N-methyl-2-pyrrolyl, 2-piperidenyl, N-methyl-2-piperidenyl, benzyl, o-tolyl, 2,6-dimethylphenyl, perfluorophenyl, 2,6-di(isopropyl)phenyl, or 2,4,6-trimethylphenyl.
The foregoing complexes also include certain phosphinimine complexes are disclosed in EP-A-890581. These complexes correspond to the formula: [(Rf)3—P═N]fM(K2)(Rf)3-f, wherein:
Rf is a monovalent ligand or two Rf groups together are a divalent ligand, preferably Rf is hydrogen or C1-4 alkyl;
M is a Group 4 metal,
K2 is a group containing delocalized π-electrons through which K2 is bound to M, said K2 group containing up to 50 atoms not counting hydrogen atoms, and
f is 1 or 2.
Cocatalysts
Each of the metal complexes (also interchangeably referred to herein as procatalysts) may be activated to form the active catalyst composition by combination with a cocatalyst, preferably a cation forming cocatalyst, a strong Lewis acid, or a combination thereof. In a preferred embodiment, the shuttling agent is employed both for purposes of chain transfer and as the optional cocatalyst component of the catalyst composition.
The metal complexes desirably are rendered catalytically active by combination with a cation forming cocatalyst, such as those previously known in the art for use with Group 4 metal olefin polymerization complexes. Suitable cation forming cocatalysts for use herein include neutral Lewis acids, such as C1-30 hydrocarbyl substituted Group 13 compounds, especially tri(hydrocarbyl)aluminum- or tri(hydrocarbyl)boron compounds and halogenated (including perhalogenated) derivatives thereof, having from 1 to 10 carbons in each hydrocarbyl or halogenated hydrocarbyl group, more especially perfluorinated tri(aryl)boron compounds, and most especially tris(pentafluoro-phenyl)borane; nonpolymeric, compatible, noncoordinating, ion forming compounds (including the use of such compounds under oxidizing conditions), especially the use of ammonium-, phosphonium-, oxonium-, carbonium-, silylium- or sulfonium-salts of compatible, noncoordinating anions, or ferrocenium-, lead- or silver salts of compatible, noncoordinating anions; and combinations of the foregoing cation forming cocatalysts and techniques. The foregoing activating cocatalysts and activating techniques have been previously taught with respect to different metal complexes for olefin polymerizations in the following references: EP-A-277,003, U.S. Pat. No. 5,153,157, U.S. Pat. No. 5,064,802, U.S. Pat. No. 5,321,106, U.S. Pat. No. 5,721,185, U.S. Pat. No. 5,350,723, U.S. Pat. No. 5,425,872, U.S. Pat. No. 5,625,087, U.S. Pat. No. 5,883,204, U.S. Pat. No. 5,919,983, U.S. Pat. No. 5,783,512, WO 99/15534, and WO99/42467.
Combinations of neutral Lewis acids, especially the combination of a trialkyl aluminum compound having from 1 to 4 carbons in each alkyl group and a halogenated tri(hydrocarbyl)boron compound having from 1 to 20 carbons in each hydrocarbyl group, especially tris(pentafluorophenyl)borane, further combinations of such neutral Lewis acid mixtures with a polymeric or oligomeric alumoxane, and combinations of a single neutral Lewis acid, especially tris(pentafluorophenyl)borane with a polymeric or oligomeric alumoxane may be used as activating cocatalysts. Preferred molar ratios of metal complex:tris(pentafluorophenyl-borane:alumoxane are from 1:1:1 to 1:5:20, more preferably from 1:1:1.5 to 1:5:10.
Suitable ion forming compounds useful as cocatalysts in one embodiment of the present invention comprise a cation which is a Bronsted acid capable of donating a proton, and a compatible, noncoordinating anion, A−. As used herein, the term “noncoordinating” means an anion or substance which either does not coordinate to the Group 4 metal containing precursor complex and the catalytic derivative derived there from, or which is only weakly coordinated to such complexes thereby remaining sufficiently labile to be displaced by a neutral Lewis base. A noncoordinating anion specifically refers to an anion which when functioning as a charge balancing anion in a cationic metal complex does not transfer an anionic substituent or fragment thereof to said cation thereby forming neutral complexes. “Compatible anions” are anions which are not degraded to neutrality when the initially formed complex decomposes and are noninterfering with desired subsequent polymerization or other uses of the complex.
Preferred anions are those containing a single coordination complex comprising a charge-bearing metal or metalloid core which anion is capable of balancing the charge of the active catalyst species (the metal cation) which may be formed when the two components are combined. Also, said anion should be sufficiently labile to be displaced by olefinic, diolefinic and acetylenically unsaturated compounds or other neutral Lewis bases such as ethers or nitrites. Suitable metals include, but are not limited to, aluminum, gold and platinum. Suitable metalloids include, but are not limited to, boron, phosphorus, and silicon. Compounds containing anions which comprise coordination complexes containing a single metal or metalloid atom are, of course, well known and many, particularly such compounds containing a single boron atom in the anion portion, are available commercially.
Preferably such cocatalysts may be represented by the following general formula:

(L*−H)g+(A)g−

wherein:

L* is a neutral Lewis base;
(L*−H)+ is a conjugate Bronsted acid of L*;
Ag− is a noncoordinating, compatible anion having a charge of g−, and
g is an integer from 1 to 3.
More preferably Ag− corresponds to the formula: [M′Q4]−;
wherein:
M′ is boron or aluminum in the +3 formal oxidation state; and
Q independently each occurrence is selected from hydride, dialkylamido, halide, hydrocarbyl, hydrocarbyloxide, halosubstituted-hydrocarbyl, halosubstituted hydrocarbyloxy, and halo-substituted silylhydrocarbyl radicals (including perhalogenated hydrocarbyl-perhalogenated hydrocarbyloxy- and perhalogenated silylhydrocarbyl radicals), said Q having up to 20 carbons with the proviso that in not more than one occurrence is Q halide. Examples of suitable hydrocarbyloxide Q groups are disclosed in U.S. Pat. No. 5,296,433.
In a more preferred embodiment, d is one, that is, the counter ion has a single negative charge and is A−. Activating cocatalysts comprising boron which are particularly useful in the preparation of catalysts of this invention may be represented by the following general formula:

(L*−H)+(BQ4)−;

wherein:

L* is as previously defined;
B is boron in a formal oxidation state of 3; and
Q is a hydrocarbyl-, hydrocarbyloxy-, fluorinated hydrocarbyl-, fluorinated hydrocarbyloxy-, or fluorinated silylhydrocarbyl-group of up to 20 nonhydrogen atoms, with the proviso that in not more than one occasion is Q hydrocarbyl.
Preferred Lewis base salts are ammonium salts, more preferably trialkylammonium salts containing one or more C12-40 alkyl groups. Most preferably, Q is each occurrence a fluorinated aryl group, especially, a pentafluorophenyl group.
Illustrative, but not limiting, examples of boron compounds which may be used as an activating cocatalyst in the preparation of the improved catalysts of this invention are tri-substituted ammonium salts such as:

    trimethylammonium tetrakis(pentafluorophenyl) borate,
    triethylammonium tetrakis(pentafluorophenyl) borate,
    tripropylammonium tetrakis(pentafluorophenyl) borate,
    tri(n-butyl)ammonium tetrakis(pentafluorophenyl) borate,
    tri(sec-butyl)ammonium tetrakis(pentafluorophenyl) borate,
    N,N-dimethylanilinium tetrakis(pentafluorophenyl) borate,
    N,N-dimethylanilinium n-butyltris(pentafluorophenyl) borate,
    N,N-dimethylanilinium benzyltris(pentafluorophenyl) borate,
    N,N-dimethylanilinium tetrakis(4-(t-butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl) borate,
    N,N-dimethylanilinium tetrakis(4-(triisopropylsilyl)-2,3,5,6-tetrafluorophenyl) borate,
    N,N-dimethylanilinium pentafluorophenoxytris(pentafluorophenyl) borate,
    N,N-diethylanilinium tetrakis(pentafluorophenyl) borate,
    N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(pentafluorophenyl) borate,
    dimethyloctadecylammonium tetrakis(pentafluorophenyl) borate,
    methyldioctadecylammonium tetrakis(pentafluorophenyl) borate,

dialkyl ammonium salts such as:

    di-(i-propyl)ammonium tetrakis(pentafluorophenyl) borate,
    methyloctadecylammonium tetrakis(pentafluorophenyl) borate,
    methyloctadodecylammonium tetrakis(pentafluorophenyl) borate, and
    dioctadecylammonium tetrakis(pentafluorophenyl) borate;

tri-substituted phosphonium salts such as:

    triphenylphosphonium tetrakis(pentafluorophenyl) borate,
    methyldioctadecylphosphonium tetrakis(pentafluorophenyl) borate, and
    tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl) borate;

di-substituted oxonium salts such as:

    diphenyloxonium tetrakis(pentafluorophenyl) borate,
    di(o-tolyl)oxonium tetrakis(pentafluorophenyl) borate, and
    di(octadecyl)oxonium tetrakis(pentafluorophenyl) borate;

di-substituted sulfonium salts such as:

    di(o-tolyl)sulfonium tetrakis(pentafluorophenyl) borate, and
    methylcotadecylsulfonium tetrakis(pentafluorophenyl) borate.


Preferred (L*−H)+ cations are methyldioctadecylammonium cations, dimethyloctadecylammonium cations, and ammonium cations derived from mixtures of trialkyl amines containing one or 2 C14-18 alkyl groups.
Another suitable ion forming, activating cocatalyst comprises a salt of a cationic oxidizing agent and a noncoordinating, compatible anion represented by the formula:

(Oxh+)g(Ag−)h,

wherein:

Oxh+ is a cationic oxidizing agent having a charge of h+;
h is an integer from 1 to 3; and
Ag− and g are as previously defined.
Examples of cationic oxidizing agents include: ferrocenium, hydrocarbyl-substituted ferrocenium, Ag+′ or Pb+2. Preferred embodiments of Ag− are those anions previously defined with respect to the Bronsted acid containing activating cocatalysts, especially tetrakis(pentafluorophenyl)borate.
Another suitable ion forming, activating cocatalyst comprises a compound which is a salt of a carbenium ion and a noncoordinating, compatible anion represented by the formula:

[C]+A−

wherein:

[C]+ is a C1-20 carbenium ion; and
A− is a noncoordinating, compatible anion having a charge of −1. A preferred carbenium ion is the trityl cation, that is triphenylmethylium.
A further suitable ion forming, activating cocatalyst comprises a compound which is a salt of a silylium ion and a noncoordinating, compatible anion represented by the formula:

(Q13Si)+A−

wherein:

Q1 is C1-10 hydrocarbyl, and A− is as previously defined.
Preferred silylium salt activating cocatalysts are trimethylsilylium tetrakispentafluorophenylborate, triethylsilylium tetrakispentafluorophenylborate and ether substituted adducts thereof. Silylium salts have been previously generically disclosed in J. Chem. Soc. Chem. Comm., 1993, 383-384, as well as Lambert, J. B., et al., Organometallics, 1994, 13, 2430-2443. The use of the above silylium salts as activating cocatalysts for addition polymerization catalysts is disclosed in U.S. Pat. No. 5,625,087.
Certain complexes of alcohols, mercaptans, silanols, and oximes with tris(pentafluorophenyl)borane are also effective catalyst activators and may be used according to the present invention. Such cocatalysts are disclosed in U.S. Pat. No. 5,296,433.
Suitable activating cocatalysts for use herein also include polymeric or oligomeric alumoxanes, especially methylalumoxane (MAO), triisobutyl aluminum modified methylalumoxane (MMAO), or isobutylalumoxane; Lewis acid modified alumoxanes, especially perhalogenated tri(hydrocarbyl)aluminum- or perhalogenated tri(hydrocarbyl)boron modified alumoxanes, having from 1 to 10 carbons in each hydrocarbyl or halogenated hydrocarbyl group, and most especially tris(pentafluorophenyl)borane modified alumoxanes. Such cocatalysts are previously disclosed in U.S. Pat. Nos. 6,214,760, 6,160,146, 6,140,521, and 6,696,379.
A class of cocatalysts comprising non-coordinating anions generically referred to as expanded anions, further disclosed in U.S. Pat. No. 6,395,671, may be suitably employed to activate the metal complexes of the present invention for olefin polymerization. Generally, these cocatalysts (illustrated by those having imidazolide, substituted imidazolide, imidazolinide, substituted imidazolinide, benzimidazolide, or substituted benzimidazolide anions) may be depicted as follows:




wherein:

A*+ is a cation, especially a proton containing cation, and preferably is a trihydrocarbyl ammonium cation containing one or two C10-40 alkyl groups, especially a methyldi(C14-20 alkyl)ammonium cation,
Q3, independently each occurrence, is hydrogen or a halo, hydrocarbyl, halocarbyl, halohydrocarbyl, silylhydrocarbyl, or silyl, (including mono-, di- and tri(hydrocarbyl)silyl) group of up to 30 atoms not counting hydrogen, preferably C1-20 alkyl, and
Q2 is tris(pentafluorophenyl)borane or tris(pentafluorophenyl)alumane).
Examples of these catalyst activators include trihydrocarbylammonium-salts, especially, methyldi(C14-20 alkyl)ammonium-salts of:

    bis(tris(pentafluorophenyl)borane)imidazolide,
    bis(tris(pentafluorophenyl)borane)-2-undecylimidazolide,
    bis(tris(pentafluorophenyl)borane)-2-heptadecylimidazolide,
    bis(tris(pentafluorophenyl)borane)-4,5-bis(undecyl)imidazolide,
    bis(tris(pentafluorophenyl)borane)-4,5-bis(heptadecyl)imidazolide,
    bis(tris(pentafluorophenyl)borane)imidazolinide,
    bis(tris(pentafluorophenyl)borane)-2-undecylimidazolinide,
    bis(tris(pentafluorophenyl)borane)-2-heptadecylimidazolinide, bis(tris(pentafluorophenyl)borane)-4,5-bis(undecyl)imidazolinide,
    bis(tris(pentafluorophenyl)borane)-4,5-bis(heptadecyl)imidazolinide,
    bis(tris(pentafluorophenyl)borane)-5,6-dimethylbenzimidazolide,
    bis(tris(pentafluorophenyl)borane)-5,6-bis(undecyl)benzimidazolide,
    bis(tris(pentafluorophenyl)alumane)imidazolide,
    bis(tris(pentafluorophenyl)alumane)-2-undecylimidazolide,
    bis(tris(pentafluorophenyl)alumane)-2-heptadecylimidazolide,
    bis(tris(pentafluorophenyl)alumane)-4,5-bis(undecyl)imidazolide,
    bis(tris(pentafluorophenyl)alumane)-4,5-bis(heptadecyl)imidazolide,
    bis(tris(pentafluorophenyl)alumane)imidazolinide,
    bis(tris(pentafluorophenyl)alumane)-2-undecylimidazolinide,
    bis(tris(pentafluorophenyl)alumane)-2-heptadecylimidazolinide,
    bis(tris(pentafluorophenyl)alumane)-4,5-bis(undecyl)imidazolinide,
    bis(tris(pentafluorophenyl)alumane)-4,5-bis(heptadecyl)imidazolinide,
    bis(tris(pentafluorophenyl)alumane)-5,6-dimethylbenzimidazolide, and
    bis(tris(pentafluorophenyl)alumane)-5,6-bis(undecyl)benzimidazolide.


Other activators include those described in PCT publication WO 98/07515 such as tris(2,2′,2′′-nonafluorobiphenyl)fluoroaluminate. Combinations of activators are also contemplated by the invention, for example, alumoxanes and ionizing activators in combinations, see for example, EP-A-0 573120, PCT publications WO 94/07928 and WO 95/14044 and U.S. Pat. Nos. 5,153,157 and 5,453,410. WO 98/09996 describes activating catalyst compounds with perchlorates, periodates and iodates, including their hydrates. WO 99/18135 describes the use of organoboroaluminum activators. WO 03/10171 discloses catalyst activators that are adducts of Bronsted acids with Lewis acids. Other activators or methods for activating a catalyst compound are described in for example, U.S. Pat. Nos. 5,849,852, 5,859,653, 5,869,723, EP-A-615981, and PCT publication WO 98/32775. All of the foregoing catalyst activators as well as any other know activator for transition metal complex catalysts may be employed alone or in combination according to the present invention, however, for best results alumoxane containing cocatalysts are avoided.
The molar ratio of catalyst/cocatalyst employed preferably ranges from 1:10,000 to 100:1, more preferably from 1:5000 to 10:1, most preferably from 1:1000 to 1:1. Alumoxane, when used by itself as an activating cocatalyst, is employed in large quantity, generally at least 100 times the quantity of metal complex on a molar basis. Tris(pentafluorophenyl)borane, where used as an activating cocatalyst is employed in a molar ratio to the metal complex of from 0.5:1 to 10:1, more preferably from 1:1 to 6:1 most preferably from 1:1 to 5:1. The remaining activating cocatalysts are generally employed in approximately equimolar quantity with the metal complex.
The process of the invention employing a catalyst one or more cocatalysts and chain shuttling agent may be further elucidated by reference to FIG. 1, where there is illustrated activated catalyst, 10, which under polymerization conditions forms a polymer chain, 13, attached to the active catalyst site, 12. A chain shuttling agent, 14, attaches to a polymer chain produced by an active catalyst site, and subsequently causes insertion of the chain segment into the active catalyst site to prepare a second generation polymer 16, which undergoes additional chain growth under polymerization conditions different from those during which the initial polymer segment is formed thereby forming a pseudo-block copolymer, 18 attached to the active catalyst. The respective polymer segments formed in the process are distinguishable because the polymerization conditions in existence at the time of formation of the respective blocks or segments are different and the chain shuttling agent is able to prolong the polymer life time (that is the time during which further polymer growth may occur) until two or more different polymerization environments are experienced. There may be repeated exchanges between the active catalyst and the shuttling agent occurring under various differing polymerization conditions. The resulting copolymer comprises blocks or segments of differing properties whenever exchange to an area of the reactor operating under differing reaction conditions occurs. By cycling the foregoing exchange several times, preferably many times, the comonomer distribution or other distinguishing property in the resulting blocks becomes more random and approaches a most probable distribution.
The growing polymer chains may be recovered while attached to a chain shuttling agent and functionalized if desired. Alternatively, the resulting polymer may be recovered by scission from the active catalyst site or from the shuttling agent, through use of a proton source or other killing agent.
During the polymerization, the reaction mixture is contacted with the activated catalyst composition according to any suitable polymerization conditions. The process is desirably characterized by use of elevated temperatures and pressures. Hydrogen may be employed as a separate chain transfer agent for molecular weight control according to known techniques if desired. All of the foregoing process conditions may be varied continuously or discontinuously over separate regions of the reactor or among different reactors according to the invention. As in other similar polymerizations, it is highly desirable that the monomers and solvents employed be of sufficiently high purity that catalyst deactivation does not occur. Any suitable technique for monomer purification such as devolatilization at reduced pressure, contacting with molecular sieves or high surface area alumina, or a combination of the foregoing processes may be employed.
Supports may be employed in the present invention, especially in slurry or gas-phase polymerizations. Suitable supports include solid, particulated, high surface area, metal oxides, metalloid oxides, or mixtures thereof (interchangeably referred to herein as an inorganic oxide). Examples include: talc, silica, alumina, magnesia, titania, zirconia, Sn2O3, aluminosilicates, borosilicates, clays, and mixtures thereof. Suitable supports preferably have a surface area as determined by nitrogen porosimetry using the B.E.T. method from 10 to 1000 m2/g, and preferably from 100 to 600 m2/g. The average particle size typically is from 0.1 to 500 μm, preferably from 1 to 200 μm, more preferably 10 to 100 μm.
In one embodiment of the invention the present catalyst composition and optional support may be spray dried or otherwise recovered in solid, particulated form to provide a composition that is readily transported and handled. Suitable methods for spray drying a liquid containing slurry are well known in the art and usefully employed herein. Preferred techniques for spray drying catalyst compositions for use herein are described in U.S. Pat. Nos. 5,648,310 and 5,672,669.
The polymerization is desirably carried out as a continuous polymerization, preferably a continuous, solution polymerization, in which catalyst components, shuttling agent(s), monomers, and optionally solvent, adjuvants, scavengers, and polymerization aids are continuously supplied to the reaction zone and polymer product continuously removed there from. Within the scope of the terms “continuous” and “continuously” as used in this context are those processes in which there are intermittent additions of reactants and removal of products at small regular or irregular intervals, so that, over time, the overall process is substantially continuous. Moreover, as previously explained, a monomer gradient, temperature gradient, pressure gradient, or other difference in polymerization conditions is maintained between at least two regions of the reactor undergoing polymerization or in differing reactors connected in a closed loop or cycle, so that polymer segments of differing composition such as comonomer content, crystallinity, density, tacticity, regio-regularity, or other chemical or physical difference are formed at different times during formation of the growing polymer chain.
The process can be operated in a high pressure, solution, slurry, or gas phase polymerization process. For a solution polymerization process it is desirable to employ homogeneous dispersions of the catalyst components in a liquid diluent in which the polymer is soluble under the polymerization conditions employed. One such process utilizing an extremely fine silica or similar dispersing agent to produce such a homogeneous catalyst dispersion where either the metal complex or the cocatalyst is only poorly soluble is disclosed in U.S. Pat. No. 5,783,512. A high pressure process is usually carried out at temperatures from 100° C. to 400° C. and at pressures above 500 bar (50 MPa). A slurry process typically uses an inert hydrocarbon diluent and temperatures of from 0° C. up to a temperature just below the temperature at which the resulting polymer becomes substantially soluble in the inert polymerization medium. Preferred temperatures in a slurry polymerization are from 30° C., preferably from 60° C. up to 115° C., preferably up to 100° C. Pressures typically range from atmospheric (100 kPa) to 500 psi (3.4 MPa).
In all of the foregoing processes, continuous or substantially continuous polymerization conditions are preferably employed. The use of such polymerization conditions, especially continuous, solution polymerization processes, allows the use of elevated reactor temperatures which results in the economical production of pseudo-block copolymers in high yields and efficiencies. Both homogeneous and plug-flow type reaction conditions may be employed with the proviso that a gradient of at least one process condition with respect to polymer chain formation over time is achieved. Desirably, at least some polymer is present at the point of catalyst or monomer addition. This may be accomplished in one embodiment by use of varying quantities of recycle (including no recycle). A highly preferred reactor for use herein is a loop or tubular reactor. Also suitable is the use of multiple reactors, especially multiple continuous stirred or back-mixed reactors (CSTR), desirably connected in series, or multiple zones in a reactor.
The metal complex may be prepared as a homogeneous composition by addition of the requisite metal complex or multiple complexes to a solvent in which the polymerization will be conducted or in a diluent compatible with the ultimate reaction mixture. The desired cocatalyst or activator and the shuttling agent may be combined with the catalyst composition either prior to, simultaneously with, or after combination with the monomers to be polymerized and any additional reaction diluent.
At all times, the individual ingredients as well as any active catalyst composition must be protected from oxygen, moisture and other catalyst poisons. Therefore, the catalyst components, shuttling agent and activated catalysts must be prepared and stored in an oxygen and moisture free atmosphere, preferably under a dry, inert gas such as nitrogen.
Without limiting in any way the scope of the invention, one means for carrying out such a polymerization process is as follows. In one or more loop reactors operating under solution polymerization conditions, the monomers to be polymerized are introduced continuously together with any solvent or diluent at one part of the reactor. The reactor contains a liquid phase composed substantially of monomers together with any solvent or diluent and dissolved polymer. Preferred solvents include C4-10 hydrocarbons or mixtures thereof, especially alkanes such as hexane or mixtures of alkanes, as well as one or more of the monomers employed in the polymerization. Examples of suitable loop reactors and a variety of suitable operating conditions for use therewith, including the use of multiple loop reactors, operating in series, are found in U.S. Pat. Nos. 5,977,251, 6,319,989 and 6,683,149.
Catalyst along with cocatalyst and chain shuttling agent are continuously or intermittently introduced in the reactor liquid phase or any recycled portion thereof at a minimum of one location. The reactor temperature and pressure may be controlled by adjusting the solvent/monomer ratio, the catalyst addition rate, as well as by cooling or heating coils, jackets or both. The polymerization rate is controlled by the rate of catalyst addition. The ethylene content of the polymer product is determined by the ratio of ethylene to comonomer in the reactor, which is controlled by manipulating the respective feed rates of these components to the reactor. The polymer product molecular weight is controlled, optionally, by controlling other polymerization variables such as the temperature, monomer concentration, or by the previously mentioned chain shuttling agent, as is well known in the art. Between at least two regions of the reactor, a differential in at least one process condition is established. Preferably for use in formation of a copolymer of two or more monomers, the difference is a difference in comonomer content. Upon exiting the reactor, the effluent is contacted with a catalyst kill agent such as water, steam or an alcohol. The polymer solution is optionally heated, and the polymer product is recovered by flashing off gaseous monomers as well as residual solvent or diluent at reduced pressure, and, if necessary, conducting further devolatilization in equipment such as a devolatilizing extruder. In a continuous process the mean residence time of the catalyst and polymer in the reactor generally is from 5 minutes to 8 hours, and preferably from 10 minutes to 6 hours.
Alternatively, the foregoing polymerization may be carried out in a plug flow reactor with a monomer, catalyst, shuttling agent, temperature or other gradient established between differing regions thereof, optionally accompanied by separated addition of catalysts and/or chain shuttling agent, and operating under adiabatic or non-adiabatic polymerization conditions.
The catalyst composition may also be prepared and employed as a heterogeneous catalyst by adsorbing the requisite components on an inert inorganic or organic particulated solid, as previously disclosed. In a preferred embodiment, a heterogeneous catalyst is prepared by co-precipitating the metal complex and the reaction product of an inert inorganic compound and an active hydrogen containing activator, especially the reaction product of a tri(C1-4 alkyl) aluminum compound and an ammonium salt of a hydroxyaryltris(pentafluorophenyl)borate, such as an ammonium salt of (4-hydroxy-3,5-ditertiarybutylphenyl)tris(pentafluorophenyl)borate. When prepared in heterogeneous or supported form, the catalyst composition may be employed in a slurry or a gas phase polymerization. As a practical limitation, slurry polymerization takes place in liquid diluents in which the polymer product is substantially insoluble. Preferably, the diluent for slurry polymerization is one or more hydrocarbons with less than 5 carbon atoms. If desired, saturated hydrocarbons such as ethane, propane or butane may be used in whole or part as the diluent. As with a solution polymerization, the α-olefin comonomer or a mixture of different x-olefin monomers may be used in whole or part as the diluent. Most preferably at least a major part of the diluent comprises the α-olefin monomer or monomers to be polymerized.
Preferably for use in gas phase polymerization processes, the support material and resulting catalyst has a median particle diameter from 20 to 200 μm, more preferably from 30 μm to 150 μm, and most preferably from 50 μm to 100 μm. Preferably for use in slurry polymerization processes, the support has a median particle diameter from 1 μm to 200 μm, more preferably from 5 μm to 100 μm, and most preferably from 10 μm to 80 μm.
Suitable gas phase polymerization process for use herein are substantially similar to known processes used commercially on a large scale for the manufacture of polypropylene, ethylene/α-olefin copolymers, and other olefin polymers. The gas phase process employed can be, for example, of the type which employs a mechanically stirred bed or a gas fluidized bed as the polymerization reaction zone. Preferred is the process wherein the polymerization reaction is carried out in a vertical cylindrical polymerization reactor containing a fluidized bed of polymer particles supported or suspended above a perforated plate or fluidization grid, by a flow of fluidization gas.
The gas employed to fluidize the bed comprises the monomer or monomers to be polymerized, and also serves as a heat exchange medium to remove the heat of reaction from the bed. The hot gases emerge from the top of the reactor, normally via a tranquilization zone, also known as a velocity reduction zone, having a wider diameter than the fluidized bed and wherein fine particles entrained in the gas stream have an opportunity to gravitate back into the bed. It can also be advantageous to use a cyclone to remove ultra-fine particles from the hot gas stream. The gas is then normally recycled to the bed by means of a blower or compressor and one or more heat exchangers to strip the gas of the heat of polymerization.
A preferred method of cooling of the bed, in addition to the cooling provided by the cooled recycle gas, is to feed a volatile liquid to the bed to provide an evaporative cooling effect, often referred to as operation in the condensing mode. The volatile liquid employed in this case can be, for example, a volatile inert liquid, for example, a saturated hydrocarbon having 3 to 8, preferably 4 to 6, carbon atoms. In the case that the monomer or comonomer itself is a volatile liquid, or can be condensed to provide such a liquid, this can suitably be fed to the bed to provide an evaporative cooling effect. The volatile liquid evaporates in the hot fluidized bed to form gas which mixes with the fluidizing gas. If the volatile liquid is a monomer or comonomer, it will undergo some polymerization in the bed. The evaporated liquid then emerges from the reactor as part of the hot recycle gas, and enters the compression/heat exchange part of the recycle loop. The recycle gas is cooled in the heat exchanger and, if the temperature to which the gas is cooled is below the dew point, liquid will precipitate from the gas. This liquid is desirably recycled continuously to the fluidized bed. It is possible to recycle the precipitated liquid to the bed as liquid droplets carried in the recycle gas stream. This type of process is described, for example in EP-89691; U.S. Pat. No. 4,543,399; WO-94/25495 and U.S. Pat. No. 5,352,749. A particularly preferred method of recycling the liquid to the bed is to separate the liquid from the recycle gas stream and to reinject this liquid directly into the bed, preferably using a method which generates fine droplets of the liquid within the bed. This type of process is described in WO-94/28032.
The polymerization reaction occurring in the gas fluidized bed is catalyzed by the continuous or semi-continuous addition of catalyst composition according to the invention. The catalyst composition may be subjected to a prepolymerization step, for example, by polymerizing a small quantity of olefin monomer in a liquid inert diluent, to provide a catalyst composite comprising supported catalyst particles embedded in olefin polymer particles as well.
The polymer is produced directly in the fluidized bed by polymerization of the monomer or mixture of monomers on the fluidized particles of catalyst composition, supported catalyst composition or prepolymerized catalyst composition within the bed. Start-up of the polymerization reaction is achieved using a bed of preformed polymer particles, which are preferably similar to the desired polymer, and conditioning the bed by drying with inert gas or nitrogen prior to introducing the catalyst composition, the monomers and any other gases which it is desired to have in the recycle gas stream, such as a diluent gas, hydrogen chain transfer agent, or an inert condensable gas when operating in gas phase condensing mode. The produced polymer is discharged continuously or semi-continuously from the fluidized bed as desired.
The gas phase processes most suitable for the practice of this invention are continuous processes which provide for the continuous supply of reactants to the reaction zone of the reactor and the removal of products from the reaction zone of the reactor, thereby providing a steady-state environment on the macro scale in the reaction zone of the reactor. Products are readily recovered by exposure to reduced pressure and optionally elevated temperatures (devolatilization) according to known techniques. Typically, the fluidized bed of the gas phase process is operated at temperatures greater than 50° C., preferably from 60° C. to 110° C., more preferably from 70° C. to 110° C.
Suitable gas phase processes which are adaptable for use in the process of this invention are disclosed in U.S. Pat. Nos. 4,588,790; 4,543,399; 5,352,749; 5,436,304; 5,405,922; 5,462,999; 5,461,123; 5,453,471; 5,032,562; 5,028,670; 5,473,028; 5,106,804; 5,556,238; 5,541,270; 5,608,019; and 5,616,661.
As previously mentioned, functionalized derivatives of pseudo-block copolymers are also included within the present invention. Examples include metallated polymers wherein the metal is the remnant of the catalyst or chain shuttling agent employed, as well as further derivatives thereof, for example, the reaction product of a metallated polymer with an oxygen source and then with water to form a hydroxyl terminated polymer. Additional examples include olefin terminated polymers formed by β-hydride elimination.
Because a substantial fraction of the polymeric product exiting the reactor is terminated with the chain shuttling agent, further functionalization is relatively easy. The metallated polymer species can be utilized in well known chemical reactions such as those suitable for other alkyl-aluminum, alkyl-gallium, alkyl-zinc, or alkyl-Group 1 compounds to form amine-, hydroxy-, epoxy-, and other functionalized terminated polymer products. Examples of suitable reaction techniques that are adaptable for use here in are described in Negishi, “Orgaonmetallics in Organic Synthesis”, Vol. 1 and 2, (1980), and other standard texts in organometallic and organic synthesis.
Polymer Products
Utilizing the present process, novel polymers, including pseudo-block copolymers of one or more olefin monomers, are readily prepared. Preferred polymers comprise in polymerized form at least one monomer selected from the group consisting of ethylene, propylene and 4-methyl-1-pentene. Highly desirably, the polymers are interpolymers comprising in polymerized form ethylene, propylene or 4-methyl-1-pentene and at least one different C2-20 α-olefin comonomer, and optionally one or more additional copolymerizable comonomers. Suitable comonomers are selected from diolefins, cyclic olefins, and cyclic diolefins, halogenated vinyl compounds, and vinylidene aromatic compounds.
The polymers of the invention can have a melt index, 12, from 0.01 to 2000 g/10 minutes, preferably from 0.01 to 1000 g/10 minutes, more preferably from 0.01 to 500 g/10 minutes, and especially from 0.01 to 100 g/10 minutes. Desirably, the invented polymers can have molecular weights, Mw, from 1,000 g/mole to 5,000,000 g/mole, preferably from 1000 g/mole to 1,000,000, more preferably from 1000 g/mole to 500,000 g/mole, and especially from 1,000 g/mole to 300,000 g/mole. The density of the invented polymers can be from 0.80 to 0.99 g/cm3 and preferably for ethylene containing polymers from 0.85 g/cm3 to 0.97 g/cm3.
The polymers of the invention may be differentiated from conventional, random copolymers, physical blends of polymers, and block copolymers prepared via sequential monomer addition, fluxional catalysts, anionic or cationic living polymerization techniques. The separate regions or blocks within each polymer contain gradual changes in composition (tapering) rather than distinct starting and ending points. In addition, several cycles between extremes of polymer composition, such as multiple gradual changes in comonomer distribution may be present in each polymer. For example, the comonomer distribution, tacticity, or other property of segments within the polymer may cycle several times between a maximum and minimum within the same polymer because the polymer experienced different process conditions during the course of its production and segments formed under various conditions while attached to the active catalyst are all present in the polymer. The various maxima and minima are characterized by increased crystallinity, tacticity, or other physical property, depending on the process condition being varied. Preferably, polymer is formed in regions of the reactor wherein monomer/comonomer ratio or comonomer content is varied. Because the polymer products have multiple blocks or segments, but few or none of the blocks are identical in size or composition, they are referred to as pseudo-block copolymers. The resulting polymers have properties approximating in many respects, those of pure block copolymers, and in some aspects exceeding the properties of pure block copolymers. In a final distinguishing feature, the blocks or segments of the pseudo-block copolymers in one embodiment of the invention may be shown to gradually change in one or more physical properties or measurements over sets of adjacent blocks rather than abruptly change between blocks. Preferred polymers have at least 4, more preferably at least 5 segments formed according to the present invention.
Compared to a random copolymer of the same monomers and monomer content at equivalent crystallinity or modulus, the polymers of the invention have one or more distinguishing features, including better (higher) heat resistance as measured by melting point, higher TMA penetration temperature, higher high-temperature tensile strength, and/or higher high-temperature torsion modulus as determined by dynamic mechanical analysis. Compared to a random copolymer comprising the same monomers and monomer content, the inventive polymers have one or more of the following: lower compression set, particularly at elevated temperatures, lower stress relaxation, higher creep resistance, higher tear strength, higher blocking resistance, faster setup due to higher crystallization (solidification) temperature, higher recovery (particularly at elevated temperatures), better abrasion resistance, higher retractive force, and better oil and filler acceptance.
The polymers desirably comprise distributions in number, block size, and/or composition of polymer blocks, which are Schultz-Flory or most probable distributions.
Other highly desirable compositions according to the present invention are elastomeric interpolymers of ethylene, a C3-20 α-olefin, especially propylene, and optionally one or more diene monomers. Preferred α-olefins for use in this embodiment of the present invention are designated by the formula CH2═CHR*, where R* is a linear or branched alkyl group of from 1 to 12 carbon atoms. Examples of suitable α-olefins include, but are not limited to, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene. A particularly preferred α-olefin is propylene. The propylene based polymers are generally referred to in the art as EP or EPDM polymers depending on whether a copolymerized diene is also present. Suitable dienes for use in preparing pseudo-block EPDM type polymers include conjugated or non-conjugated, straight or branched chain-, cyclic- or polycyclic-dienes containing from 4 to 20 carbons. Preferred dienes include 1,4-pentadiene, 1,4-hexadiene, 5-ethylidene-2-norbornene, dicyclopentadiene, cyclohexadiene, and 5-butylidene-2-norbornene. A particularly preferred diene is 5-ethylidene-2-norbornene.
Because the diene containing polymers contain alternating segments or blocks containing greater or lesser quantities of the diene (including none) and α-olefin (including none), the total quantity of diene and α-olefin may be reduced without loss of subsequent polymer properties. That is, because the diene and α-olefin monomers are preferentially incorporated into one type of block of the polymer rather than uniformly or randomly throughout the polymer, they are more efficiently utilized and subsequently the crosslink density of the polymer can be better controlled. Such crosslinkable elastomers and the cured products have advantaged properties, including higher tensile strength and better elastic recovery.
Further preferably, the pseudo-block polymers of the invention have an ethylene content from 1 to 99 percent, a diene content from 0 to 10 percent, and a styrene and/or C3-8 α-olefin content from 99 to 1 percent, based on the total weight of the polymer. Preferred polymers are interpolymers of ethylene, propylene and optionally a diene. Desirably, the polymers of the invention have a weight average molecular weight (Mw) from 10,000 to 2,500,000, a polydispersity less than 3.5, more preferably less than 3.0, and a Mooney viscosity (ML (1+4) 125° C.) from 1 to 250.
More preferably, such polymers have an ethylene content from 10 to 98 percent, a diene content from 0 to 6 percent, an α-olefin content from 2 to 90 percent, a Mw from 20,000 to 250,000, a polydispersity from 1.5 to 3.0, and a Mooney viscosity from 10 to 100. Especially preferred interpolymers are propylene/ethylene copolymers containing greater than 10 percent ethylene, preferably greater than 15 percent ethylene, and having a pellet blocking strength less than or equal to 3 kPa and or a compression set less than or equal to 50 percent at 23° C.
The polymer may be oil extended with from 5 to 75 percent, preferably from 10 to 60 percent, more preferably from 20 to 50 percent, based on total composition weight, of a processing oil. Suitable oils include any oil that is conventionally used in manufacturing extended EPDM rubber formulations. Examples include both naphthenic- and paraffinic-oils, with paraffinic oils being preferred.
Highly desirably a curable EPDM rubber formulation is prepared by incorporation of one or more curing agents along with conventional accelerators or other adjuvants. Suitable curing agents are sulfur based. Examples of suitable sulfur based curing agents include, but are not limited to, sulfur, tetramethylthiuram disulfide (TMTD), dipentamethylenethiuram tetrasulfide (DPTT), 2-mercaptobenzothiazole (MBT), 2-mercaptobenzothiazolate disulfide (MBTS), zinc-2-mercaptobenozothiazolate (ZMBT), zinc diethyldithiocarbamatezinc (ZDEC), zinc dibutyldithiocarbamate (ZDBC), dipentamethylenethiuram tetrasulfide (DPTT), N-t-butylbenzothiazole-2-sulfanamide (TBBS), and mixtures thereof. A preferred cure system includes a combination of sulfur, MBT and TMTD. Desirably, the foregoing components are employed in amounts from 0.1 to 5 percent, based on total composition weight.
A preferred elastomer composition according to this embodiment of the invention may also include carbon black. Preferably, the carbon black is present in the amount of from 10 to 80 percent, more preferably from 20 to 60 percent, based on total composition weight.
Additional components of the present formulations usefully employed according to the present invention include various other ingredients in amounts that do not detract from the properties of the resultant composition. These ingredients include, but are not limited to, activators such as calcium or magnesium oxide; fatty acids such as stearic acid and salts thereof; fillers and reinforcers such as calcium or magnesium carbonate, silica, and aluminum silicates; plasticizers such as dialkyl esters of dicarboxylic acids; antidegradants; softeners; waxes; and pigments.
Applications and End Uses
The polymers of the invention can be usefully employed in a variety of conventional thermoplastic fabrication processes to produce useful articles, including objects comprising at least one film layer, such as a monolayer film, or at least one layer in a multilayer film prepared by cast, blown, calendered, or extrusion coating processes; molded articles, such as blow molded, injection molded, or rotomolded articles; extrusions; fibers; and woven or non-woven fabrics. Thermoplastic compositions comprising the present polymers, include blends with other natural or synthetic polymers, additives, reinforcing agents, ignition resistant additives, antioxidants, stabilizers, colorants, extenders, crosslinkers, blowing agents, and plasticizers. Of particular utility are multi-component fibers such as core/sheath fibers, having an outer surface layer, comprising at least in part, one or more polymers of the invention.
Fibers that may be prepared from the present polymers or blends include staple fibers, tow, multicomponent, sheath/core, twisted, and monofilament. Suitable fiber forming processes include spinbonded, melt blown techniques, as disclosed in U.S. Pat. Nos. 4,430,563, 4, 663,220, 4,668,566, and 4,322,027, gel spun fibers as disclosed in U.S. Pat. No. 4,413,110, woven and nonwoven fabrics, as disclosed in U.S. Pat. No. 3,485,706, or structures made from such fibers, including blends with other fibers, such as polyester, nylon or cotton, thermoformed articles, extruded shapes, including profile extrusions and co-extrusions, calendared articles, and drawn, twisted, or crimped yarns or fibers. The new polymers described herein are also useful for wire and cable coating operations, as well as in sheet extrusion for vacuum forming operations, and forming molded articles, including the use of injection molding, blow molding process, or rotomolding processes. Compositions comprising the olefin polymers can also be formed into fabricated articles such as those previously mentioned using conventional polyolefin processing techniques which are well known to those skilled in the art of polyolefin processing.
Dispersions (both aqueous and non-aqueous) can also be formed using the present polymers or formulations comprising the same. Frothed foams comprising the invented polymers can also be formed, as disclosed in PCT application No. 2004/027593, filed Aug. 25, 2004. The polymers may also be crosslinked by any known means, such as the use of peroxide, electron beam, silane, azide, or other cross-linking technique. The polymers can also be chemically modified, such as by grafting (for example by use of maleic anhydride (MAH), silanes, or other grafting agent), halogenation, amination, sulfonation, or other chemical modification.
Additives and adjuvants may be included in any formulation comprising the present polymers. Suitable additives include fillers, such as organic or inorganic particles, including clays, talc, titanium dioxide, zeolites, powdered metals, organic or inorganic fibers, including carbon fibers, silicon nitride fibers, steel wire or mesh, and nylon or polyester cording, nano-sized particles, clays, and so forth; tackifiers, oil extenders, including paraffinic or napthelenic oils; and other natural and synthetic polymers, including other polymers according to the invention.
Suitable polymers for blending with the polymers of the invention include thermoplastic and non-thermoplastic polymers including natural and synthetic polymers. Exemplary polymers for blending include polypropylene, (both impact modifying polypropylene, isotactic polypropylene, atactic polypropylene, and random ethylene/propylene copolymers), various types of polyethylene, including high pressure, free-radical LDPE, Ziegler Natta LLDPE, metallocene PE, including multiple reactor PE (“in reactor” blends of Ziegler-Natta PE and metallocene PE, such as products disclosed in U.S. Pat. Nos. 6,545,088, 6,538,070, 6,566,446, 5,844,045, 5,869,575, and 6,448,341, ethylene-vinyl acetate (EVA), ethylene/vinyl alcohol copolymers, polystyrene, impact modified polystyrene, ABS, styrene/butadiene block copolymers and hydrogenated derivatives thereof (SBS and SEBS), and thermoplastic polyurethanes. Homogeneous polymers such as olefin plastomers and elastomers, ethylene and propylene-based copolymers (for example polymers available under the trade designation VERSIFYTM available from The Dow Chemical Company and VISTAMAXXTM available from ExxonMobil can also be useful as components in blends comprising the present polymers.
Suitable end uses for the foregoing products include films and fibers; molded articles, such as tooth brush handles and appliance handles; gaskets and profiles; adhesives (including hot melt adhesives and pressure sensitive adhesives); footwear (including shoe soles and shoe liners); auto interior parts and profiles; foam goods (both open and closed cell); impact modifiers for other thermoplastic polymers such as EPDM, isotactic polypropylene, or other olefin polymers; coated fabrics; hoses; tubing; weather stripping; cap liners; flooring; and viscosity index modifiers, also known as pour point modifiers, for lubricants.
In a highly desired embodiment of the invention thermoplastic compositions comprising a thermoplastic matrix polymer, especially isotactic polypropylene, and an elastomeric pseudo-block copolymer according to the invention, are uniquely capable of forming core-shell type particles having hard crystalline or semi-crystalline blocks in the form of a core surrounded by soft or elastomeric blocks forming a “shell” around the occluded domains of hard polymer. These particles are formed and dispersed within the matrix polymer by the forces incurred during melt compounding or blending. This highly desirable morphology is believed to result due to the unique physical properties of the multi-block copolymers which enable compatible polymer regions such as the matrix and higher comonomer content elastomeric regions of the pseudo-block copolymer to self-assemble in the melt due to thermodynamic forces. Shearing forces during compounding are believed to produce separated regions of matrix polymer encircled by elastomer. Upon solidifying, these regions become occluded elastomer particles encased in the polymer matrix.
Particularly desirable blends are thermoplastic polyolefin blends (TPO), thermoplastic elastomer blends (TPE), thermoplastic vulcanisites (TPV) and styrenic polymer blends. TPE and TPV blends may be prepared by combining the invented pseudo-block polymers, including functionalized or unsaturated derivatives thereof with an optional rubber, including conventional block copolymers, especially an SBS block copolymer, and optionally a crosslinking or vulcanizing agent. TPO blends are generally prepared by blending the invented pseudo-block copolymers with a polyolefin, and optionally a crosslinking or vulcanizing agent. The foregoing blends may be used in forming a molded object, and optionally crosslinking the resulting molded article. A similar procedure using different components has been previously disclosed in U.S. Pat. No. 6,797,779.
Suitable conventional block copolymers for this application desirably possess a Mooney viscosity (ML 1+4@100° C.) in the range from 10 to 135, more preferably from 25 to 100, and most preferably from 30 to 80. Suitable polyolefins especially include linear or low density polyethylene, polypropylene (including atactic, isotactic, syndiotactic and impact modified versions thereof) and poly(4-methyl-1-pentene). Suitable styrenic polymers include polystyrene, rubber modified polystyrene (HIPS), styrene/acrylonitrile copolymers (SAN), rubber modified SAN (ABS or AES) and styrene maleic anhydride copolymers.
The blends may be prepared by mixing or kneading the respective components at a temperature around or above the melt point temperature of one or both of the components. For most multiblock copolymers, this temperature may be above 130° C., most generally above 145° C., and most preferably above 150° C. Typical polymer mixing or kneading equipment that is capable of reaching the desired temperatures and melt plastifying the mixture may be employed. These include mills, kneaders, extruders (both single screw and twin-screw), Banbury mixers, and calenders. The sequence of mixing and method may depend on the final composition. A combination of Banbury batch mixers and continuous mixers may also be employed, such as a Banbury mixer followed by a mill mixer followed by an extruder. Typically, a TPE or TPV composition will have a higher loading of cross-linkable polymer (typically the conventional block copolymer containing unsaturation) compared to TPO compositions. Generally, for TPE and TPV compositions, the weight ratio of block copolymer to pseudo-block copolymer should be from 90:10 to 10:90, more preferably from 80:20 to 20:80, and most preferably from 75:25 to 25:50. For TPO applications, the weight ratio of pseudo-block copolymer to polyolefin may be from 49:51 to 5:95, more preferably from 35:65 to 10:90. For modified styrenic polymer applications, the weight ratio of pseudo-block copolymer to polyolefin may also be from 49:51 to 5:95, more preferably from 35:65 to 10:90. The ratios may be changed by changing the viscosity ratios of the various components. There is considerable literature illustrating techniques for changing the phase continuity by changing the viscosity ratios of the constituents of a blend and a person skilled in this art may consult if necessary.
The blend compositions may contain processing oils, plasticizers, and processing aids. Rubber processing oils have a certain ASTM designations and paraffinic, napthenic or aromatic process oils are all suitable for use. Generally from 0 to 150 parts, more preferably 0 to 100 parts, and most preferably from 0 to 50 parts of oil per 100 parts of total polymer are employed. Higher amounts of oil may tend to improve the processing of the resulting product at the expense of some physical properties. Additional processing aids include conventional waxes, fatty acid salts, such as calcium stearate or zinc stearate, (poly)alcohols including glycols, (poly)alcohol ethers, including glycol ethers, (poly)esters, including (poly)glycol esters, and metal salt-, especially Group 1 or 2 metal or zinc-, salt derivatives thereof.
It is known that non-hydrogenated rubbers such as those comprising polymerized forms of butadiene or isoprene, including block copolymers (here-in-after diene rubbers), have lower resistance to UV, ozone, and oxidation, compared to mostly or highly saturated rubbers. In applications such as tires made from compositions containing higher concentrations of diene based rubbers, it is known to incorporate carbon black to improve rubber stability, along with anti-ozone additives or antioxidants. Pseudo-block copolymers according to the present invention possess extremely low levels of unsaturation, and find particular application as a protective surface layer (coated, coextruded or laminated) or weather resistant film adhered to articles formed from conventional diene elastomer modified polymeric compositions.
For certain of the present TPO, TPV, and TPE applications, carbon black is the additive of choice for UV absorption and stabilization. Representative examples of carbon blacks include ASTM N110, N121, N220, N231, N234, N242, N293, N299, S315, N326, N330, M332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990 and N991. These carbon blacks have iodine absorptions ranging from 9 to 145 g/kg and average pore volumes ranging from 10 to 150 cm3/100 g. Generally, smaller particle sized carbon blacks are employed, to the extent cost considerations permit. For many such applications the present pseudo-block copolymers and blends thereof require little or no carbon black, thereby allowing considerable design freedom to include alternative pigments or no pigments at all.
Compositions, including thermoplastic blends according to the invention may also contain anti-ozonants and anti-oxidants that are known to a rubber chemist of ordinary skill. The anti-ozonants may be physical protectants such as waxy materials that come to the surface and protect the part from oxygen or ozone or they may be chemical protectors that react with oxygen or ozone. Suitable chemical protectors include styrenated phenols, butylated octylated phenol, butylated di(dimethylbenzyl)phenol, p-phenylenediamines, butylated reaction products of p-cresol and dicyclopentadiene (DCPD), polyphenolic anitioxidants, hydroquinone derivatives, quinoline, diphenylene antioxidants, thioester antioxidants, and blends thereof. Some representative trade names of such products are WingstayTM S antioxidant, PolystayTM 100 antioxidant, PolystayTM 100 AZ antioxidant, PolystayTM 200 antioxidant, WingstayTM L antioxidant, WingstayTM LHLS antioxidant, WingstayTM K antioxidant, WingstayTM 29 antioxidant, WingstayTM SN-1 antioxidant, and IrganoxTM antioxidants. In some applications, the antioxidants and antiozonants used will preferably be non-staining and non-migratory.
For providing additional stability against UV radiation, hindered amine light stabilizers (HALS) and UV absorbers may be also used. Suitable examples include TinuvinTM 123, TinuvinTM 144, TinuvinTM 622, TinuvinTM 765, TinuvinTM 770, and TinuvinTM 780, available from Ciba Specialty Chemicals, and ChemisorbTM T944, available from Cytex Plastics, Houston, Tex., USA. A Lewis acid may be additionally included with a HALS compound in order to achieve superior surface quality, as disclosed in U.S. Pat. No. 6,051,681.
For some compositions, additional mixing process may be employed to pre-disperse the anti-oxidants, anti-ozonants, carbon black, UV absorbers, and/or light stabilizers to form a masterbatch, and subsequently to form polymer blends there from.
Suitable crosslinking agents (also referred to as curing or vulcanizing agents) for use herein include sulfur based, peroxide based, or phenolic based compounds. Examples of the foregoing materials are found in the art, including in U.S. Pat. Nos. 3,758,643, 3,806,558, 5,051,478, 4,104,210, 4,130,535, 4,202,801, 4,271,049, 4,340,684, 4,250,273, 4,927,882, 4,311,628 and 5,248,729.
When sulfur based curing agents are employed, accelerators and cure activators may be used as well. Accelerators are used to control the time and/or temperature required for dynamic vulcanization and to improve the properties of the resulting cross-linked article. In one embodiment, a single accelerator or primary accelerator is used. The primary accelerator(s) may be used in total amounts ranging from 0.5 to 4, preferably 0.8 to 1.5, phr, based on total composition weight. In another embodiment, combinations of a primary and a secondary accelerator might be used with the secondary accelerator being used in smaller amounts, such as from 0.05 to 3 phr, in order to activate and to improve the properties of the cured article. Combinations of accelerators generally produce articles having properties that are somewhat better than those produced by use of a single accelerator. In addition, delayed action accelerators may be used which are not affected by normal processing temperatures yet produce a satisfactory cure at ordinary vulcanization temperatures. Vulcanization retarders might also be used. Suitable types of accelerators that may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator is preferably a guanidine, dithiocarbamate or thiuram compound. Certain processing aids and cure activators such as stearic acid and ZnO may also be used. When peroxide based curing agents are used, co-activators or coagents may be used in combination therewith. Suitable coagents include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), among others. Use of peroxide crosslinkers and optional coagents used for partial or complete dynamic vulcanization are known in the art and disclosed for example in the publication, “Peroxide Vulcanization of Elastomers”, Vol. 74, No 3, July-August 2001.
When the pseudo-block copolymer containing composition is at least partially crosslinked, the degree of crosslinking may be measured by dissolving the composition in a solvent for specified duration, and calculating the percent gel or unextractable rubber. The percent gel normally increases with increasing crosslinking levels. For cured articles according to the invention, the percent gel content is desirably in the range from 5 to 100 percent.
The pseudo-block copolymers of the invention as well as blends thereof possess improved processability compared to prior art compositions, due, it is believed, to lower melt viscosity. Thus, the composition or blend demonstrates an improved surface appearance, especially when formed into a molded or extruded article. At the same time, the present compositions and blends thereof uniquely possess improved melt strength properties, thereby allowing the present pseudo-block copolymers and blends thereof, especially TPO blends, to be usefully employed in foam and in thermoforming applications where melt strength is currently inadequate.
Thermoplastic compositions according to the invention may also contain organic or inorganic fillers or other additives such as starch, talc, calcium carbonate, glass fibers, polymeric fibers (including nylon, rayon, cotton, polyester, and polyaramide), metal fibers, flakes or particles, expandable layered silicates, phosphates or carbonates, such as clays, mica, silica, alumina, aluminosilicates or aluminophosphates, carbon whiskers, carbon fibers, nanoparticles including nanotubes, wollastonite, graphite, zeolites, and ceramics, such as silicon carbide, silicon nitride or titanias. Silane based or other coupling agents may also be employed for better filler bonding.
The thermoplastic compositions of this invention, including the foregoing blends, may be processed by conventional molding techniques such as injection molding, extrusion molding, thermoforming, slush molding, over molding, insert molding, blow molding, and other techniques. Films, including multi-layer films, may be produced by cast or tentering processes, including blown film processes.
Testing Methods
In the foregoing characterizing disclosure and the examples that follow, the following analytical techniques are employed:
Standard CRYSTAF Method
Branching distributions are determined by crystallization analysis fractionation (CRYSTAF) using a CRYSTAF 200 unit commercially available from PolymerChar, Valencia, Spain. The samples are dissolved in 1,2,4 trichlorobenzene at 160° C. (0.66 mg/mL) for 1 hr and stabilized at 95° C. for 45 minutes. The sampling temperatures range from 95 to 30° C. at a cooling rate of 0.2° C./min. An infrared detector is used to measure the polymer solution concentrations. The cumulative soluble concentration is measured as the polymer crystallizes while the temperature is decreased. The analytical derivative of the cumulative profile reflects the short chain branching distribution of the polymer.
The CRYSTAF peak temperature and area are identified by the peak analysis module included in the CRYSTAF Software (Version 2001.b, PolymerChar, Valencia, Spain). The CRYSTAF peak finding routine identifies a peak temperature as a maximum in the dW/dT and the area between the largest positive inflections on either side of the identified peak in the derivative curve.
DSC Standard Method
Differential Scanning Calorimetry results are determined using a TAI model Q1000 DSC equipped with an RCS cooling accessory and an autosampler. A nitrogen purge gas flow of 50 ml/min is used. The sample is pressed into a thin film and melted in the press at 175° C. and then air-cooled to room temperature (25° C.). 10 mg of material in the form of a 5-6 mm diameter disk is accurately weighed and placed in an aluminum foil pan (ca 50 mg) which is then crimped shut. The thermal behavior of the sample is investigated with the following temperature profile. The sample is rapidly heated to 180° C. and held isothermal for 3 minutes in order to remove any previous thermal history. The sample is then cooled to −40° C. at 10° C./min cooling rate and held at −40° C. for 3 minutes. The sample is then heated to 150° C. at 10° C./min. heating rate. The cooling and second heating curves are recorded.
The DSC melting peak is measured as the maximum in heat flow rate (W/g) with respect to the linear baseline drawn between −30° C. and end of melting. The heat of fusion is measured as the area under the melting curve between −30° C. and the end of melting using a linear baseline.
Abrasion Resistance
Abrasion resistance is measured on compression molded plaques according to ISO 4649. The average value of 3 measurements is reported. Plaques of 6.4 mm thick are compression molded using a hot press (Carver Model #4095-4PR100R). The pellets are placed between polytetrafluoroethylene sheets, heated at 190° C. at 55 psi (380 kPa) for 3 min, followed by 1.3 MPa for 3 min, and then 2.6 MPa for 3 min. Next the film is cooled in the press with running cold water at 1.3 MPa for 1 min.
GPC Method
The gel permeation chromatographic system consists of either a Polymer Laboratories Model PL-210 or a Polymer Laboratories Model PL-220 instrument. The column and carousel compartments are operated at 140° C. Three Polymer Laboratories 10-micron Mixed-B columns are used. The solvent is 1,2,4 trichlorobenzene. The samples are prepared at a concentration of 0.1 grams of polymer in 50 milliliters of solvent containing 200 ppm of butylated hydroxytoluene (BHT). Samples are prepared by agitating lightly for 2 hours at 160° C. The injection volume used is 100 microliters and the flow rate is 1.0 ml/minute.
Calibration of the GPC column set is performed with 21 narrow molecular weight distribution polystyrene standards with molecular weights ranging from 580 to 8,400,000, arranged in 6 “cocktail” mixtures with at least a decade of separation between individual molecular weights. The standards are purchased from Polymer Laboratories (Shropshire, UK). The polystyrene standards are prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000, and 0.05 grams in 50 milliliters of solvent for molecular weights less than 1,000,000. The polystyrene standards are dissolved at 80° C. with gentle agitation for 30 minutes. The narrow standards mixtures are run first and in order of decreasing highest molecular weight component to minimize degradation. The polystyrene standard peak molecular weights are converted to polyethylene molecular weights using the following equation (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)): Mpolyethylene=0.431(Mpolystyrene).
Polyetheylene equivalent molecular weight calculations are performed using Viscotek TriSEC software Version 3.0.
Compression Set
Compression set is measured according to ASTM D 395. The sample is prepared by stacking 25.4 mm diameter round discs of 3.2 mm, 2.0 mm, and 0.25 mm thickness until a total thickness of 12.7 mm is reached. The discs are cut from 12.7 cm×12.7 cm compression molded plaques molded with a hot press under the following conditions: zero pressure for 3 min at 190° C., followed by 86 MPa for 2 min at 190° C., followed by cooling inside the press with cold running water at 86 MPa.
Density
Density measurement are conducted according to ASTM D 1928. Measurements are made within one hour of sample pressing using ASTM D792, Method B.
Flexural/Secant Modulus
Samples are compression molded using ASTM D 1928. Flexural and 2 percent secant moduli are measured according to ASTM D-790.
Optical Properties, Tensile, Hysteresis, and Tear
Films of 0.4 mm thickness are compression molded using a hot press (Carver Model #4095-4PR1001R). The pellets are placed between polytetrafluoroethylene sheets, heated at 190° C. at 55 psi (380 kPa) for 3 min, followed by 1.3 MPa for 3 min, and then 2.6 MPa for 3 min. The film is then cooled in the press with running cold water at 1.3 MPa for 1 min. The compression molded films are used for optical measurements, tensile behavior, recovery, and stress relaxation.
Clarity is measured using BYK Gardner Haze-gard as specified in ASTM D 1746.
45° gloss is measured using BYK Gardner Glossmeter Microgloss 45° as specified in ASTM D-2457
Internal haze is measured using BYK Gardner Haze-gard based on ASTM D 1003 Procedure A. Mineral oil is applied to the film surface to remove surface scratches.
Stress-strain behavior in uniaxial tension is measured using ASTM D 1708 microtensile specimens. Samples are stretched with an Instron at 500% min−1 at 21° C. Tensile strength and elongation at break are reported from an average of 5 specimens.
100% and 300% Hysteresis is determined from cyclic loading to 100% and 300% strains according to ASTM D 1708 with an InstronTM instrument. The sample is loaded and unloaded at 267% min−1 for 3 cycles at 21° C. Cyclic experiments at 300% and 80° C. are conducted using an environmental chamber. In the 80° C. experiment, the sample is allowed to equilibrate for 45 minutes at the test temperature before testing. In the 21° C., 300% strain cyclic experiment, the retractive stress at 150% strain from the first unloading cycle is recorded. Percent recovery for all experiments are calculated from the first unloading cycle using the strain at which the load returned to the base line. The percent recovery is defined as:




  
    %
    ⁢
    
      
    
    ⁢
    Recovery
  
  =
  
    
      
        
          ɛ
          f
        
        -
        
          ɛ
          s
        
      
      
        ɛ
        f
      
    
    ×
    100
  




where εf is the strain taken for cyclic loading and εs is the strain where the load returns to the baseline during the 1st unloading cycle.
Stress relaxation is measured at 50 percent strain and 37° C. for 12 hours using an InstronTM instrument equipped with an environmental chamber. The gauge geometry was 76 mm×25 mm×0.4 mm. After equilibrating at 37° C. for 45 min in the environmental chamber, the sample was stretched to 50% strain at 333% min−1. Stress was recorded as a function of time for 12 hours. The percent stress relaxation after 12 hours was calculated using the formula:




  
    %
    ⁢
    
      
    
    ⁢
    Stress
    ⁢
    
      
    
    ⁢
    Relaxation
  
  =
  
    
      
        
          L
          0
        
        -
        
          L
          12
        
      
      
        L
        0
      
    
    ×
    100
  




where L0 is the load at 50% strain at 0 time and L12 is the load at 50 percent strain after 12 hours.

Tensile notched tear experiments are carried out on samples having a density of 0.88 g/cc or less using an InstronTM instrument. The geometry consists of a gauge section of 76 mm×13 mm×0.4 mm with a 2 mm notch cut into the sample at half the specimen length. The sample is stretched at 508 mm min−1 at 21° C. until it breaks. The tear energy is calculated as the area under the stress-elongation curve up to strain at maximum load. An average of at least 3 specimens are reported.
TMA
Thermal Mechanical Analysis is conducted on 30 mm diameter×3.3 mm thick, compression molded discs, formed at 180° C. and 10 MPa molding pressure for 5 minutes and then air quenched. The instrument used is a TMA 7, brand available from Perkin-Elmer. In the test, a probe with 1.5 mm radius tip (P/N N519-0416) is applied to the surface of the sample disc with 1N force. The temperature is raised at 5° C./min from 25° C. The probe penetration distance is measured as a function of temperature. The experiment ends when the probe has penetrated 1 mm into the sample.
DMA
Dynamic Mechanical Analysis (DMA) is measured on compression molded disks formed in a hot press at 180° C. at 10 MPa pressure for 5 minutes and then water cooled in the press at 90° C./min. Testing is conducted using an ARES controlled strain rheometer (TA instruments) equipped with dual cantilever fixtures for torsion testing.
A 1.5 mm plaque is pressed and cut in a bar of dimensions 32×12 mm. The sample is clamped at both ends between fixtures separated by 10 mm (grip separation ΔL) and subjected to successive temperature steps from −100° C. to 200° C. (5° C. per step). At each temperature the torsion modulus G′ is measured at an angular frequency of 10 rad/s, the strain amplitude being maintained between 0.1 percent and 4 percent to ensure that the torque is sufficient and that the measurement remains in the linear regime.
An initial static force of 10 g is maintained (auto-tension mode) to prevent slack in the sample when thermal expansion occurs. As a consequence, the grip separation ΔL increases with the temperature, particularly above the melting or softening point of the polymer sample. The test stops at the maximum temperature or when the gap between the fixtures reaches 65 mm.
Pellet Blocking Behavior
Pellets (150 g) are loaded into a 2′′ (5 cm) diameter hollow cylinder that is made of two halves held together by a hose clamp. A 2.75 lb (1.25 kg) load is applied to the pellets in the cylinder at 45° C. for 3 days. After 3 days, the pellets loosely consolidate into a cylindrical shaped plug. The plug is removed from the form and the pellet blocking force measured by loading the cylinder of blocked pellets in compression using an InstronTM instrument to measure the compressive force needed to break the cylinder into pellets.
Melt Properties
Melt Flow Rate (MFR) and Melt index, or 12, are measured in accordance with ASTM D1238, Condition 190° C./2.16 kg.
ATREF
Analytical temperature rising elution fractionation (ATREF) analysis is conducted according to the method described in U.S. Pat. No. 4,798,081. The composition to be analyzed is dissolved in trichlorobenzene and allowed to crystallize in a column containing an inert support (stainless steel shot) by slowly reducing the temperature to 20° C. at a cooling rate of 0.1° C./min. The column is equipped with an infrared detector. An ATREF chromatogram curve is then generated by eluting the crystallized polymer sample from the column by slowly increasing the temperature of the eluting solvent (trichlorobenzene) from 20 to 120° C. at a rate of 1.5° C./min.
SPECIFIC EMBODIMENTS
The following specific embodiments of the invention and combinations thereof are especially desirable and hereby delineated in order to provide detailed disclosure for the appended claims.
1. A process for the polymerization of one or more addition polymerizable monomers, preferably two or more addition polymerizable monomers, especially ethylene and at least one copolymerizable comonomer, propylene and at least one copolymerizable comonomer, or 4-methyl-1-pentene and at least one copolymerizable comonomer, to form a copolymer comprising multiple regions or segments of differentiated polymer composition or properties, especially regions comprising differing comonomer incorporation index, said process comprising contacting an addition polymerizable monomer or mixture of monomers under addition polymerization conditions with a composition comprising at least one olefin polymerization catalyst, a cocatalyst and a chain shuttling agent, said process being characterized by formation of at least some of the growing polymer chains under differentiated process conditions such that two or more blocks or segments formed within at least some of the resulting polymer are chemically or physically distinguishable.
2. A high molecular weight copolymer, especially such a copolymer comprising in polymerized form ethylene and a copolymerizable comonomer, propylene and at least one copolymerizable comonomer, or 4-methyl-1-pentene and at least one copolymerizable comonomer, said copolymer comprising two or more intramolecular regions or segments comprising differing chemical or physical properties, especially regions or segments of differentiated comonomer incorporation. Highly preferably the copolymer possesses a molecular weight distribution, Mw/Mn, of less than 3.0, preferably less than 2.8.
3. A polymer mixture comprising: (1) an organic or inorganic polymer, preferably a homopolymer of ethylene and/or a copolymer of ethylene and a copolymerizable comonomer, and (2) a copolymer according to the present invention or prepared according to the process of the present invention.
4. A process according to embodiment 1 wherein the catalyst comprises a metal complex corresponding to the formula:




wherein:
R11 is selected from alkyl, cycloalkyl, heteroalkyl, cycloheteroalkyl, aryl, and inertly substituted derivatives thereof containing from 1 to 30 atoms not counting hydrogen or a divalent derivative thereof;
T1 is a divalent bridging group of from 1 to 41 atoms other than hydrogen, preferably 1 to 20 atoms other than hydrogen, and most preferably a mono- or di-C1-20 hydrocarbyl substituted methylene or silane group; and
R12 is a C5-20 heteroaryl group containing Lewis base functionality, especially a pyridin-2-yl- or substituted pyridin-2-yl group or a divalent derivative thereof;
M1 is a Group 4 metal, preferably hafnium;
X1 is an anionic, neutral or dianionic ligand group;
x′ is a number from 0 to 5 indicating the number of such X1 groups; and
bonds, optional bonds and electron donative interactions are represented by lines, dotted lines and arrows respectively.
4. A process according to embodiment 1 wherein the catalyst comprises a metal complex corresponding to the formula:




wherein

    
    
        M2 is a metal of Groups 4-10 of the Periodic Table of the elements;
        T2 is a nitrogen, oxygen or phosphorus containing group;
        X2 is halo, hydrocarbyl, or hydrocarbyloxy;
        t is one or two;
        x′′ is a number selected to provide charge balance;
        and T2 and N are linked by a bridging ligand.
    
    


The skilled artisan will appreciate that the invention disclosed herein may be practiced in the absence of any component which has not been specifically disclosed.
EXAMPLES
The following examples are provided as further illustration of the invention and are not to be construed as limiting. The term “overnight”, if used, refers to a time of approximately 16-18 hours, the term “room temperature”, refers to a temperature of 20-25° C., and the term “mixed alkanes” refers to a commercially obtained mixture of C6-9 aliphatic hydrocarbons available under the trade designation Isopar E®, from Exxon Mobil Chemicals Inc. In the event the name of a compound herein does not conform to the structural representation thereof, the structural representation shall control. The synthesis of all metal complexes and the preparation of all screening experiments were carried out in a dry nitrogen atmosphere using dry box techniques. All solvents used were HPLC grade and were dried before their use.
MMAO refers to modified methylalumoxane, a triisobutylaluminum modified methylalumoxane available commercially from Akzo-Noble Corporation.
Catalyst (A1) is [N-(2,6-di(1-methylethyl)phenyl)amido)(2-isopropylphenyl)(α-naphthalen-2-diyl(6-pyridin-2-diyl)methane)]hafnium dimethyl, prepared according to the teachings of WO 03/40195, 2003US0204017, U.S. Ser. No. 10/429,024, filed May 2, 2003, and WO 04/24740.




Catalyst (A2) is [N-(2,6-di(1-methylethyl)phenyl)amido)(2-methylphenyl)(1,2-phenylene-(6-pyridin-2-diyl)methane)]hafnium dimethyl, prepared according to the teachings of WO 03/40195, 2003US0204017, U.S. Ser. No. 10/429,024, filed May 2, 2003, and WO 04/24740.




Catalyst (A3) is bis[N,N′′′-(2,4,6-tri(methylphenyl)amido)ethylenediamine]hafnium dibenzyl.




Catalyst (A4) is bis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethyl)cyclohexane-1,2-diyl zirconium (IV) dibenzyl, prepared substantially according to the teachings of US-A-2004/0010103.




Catalyst (A5) is (bis-(1-methylethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)immino)zirconium dibenzyl.




The preparation of catalyst (A5) is conducted as follows.
a) Preparation of (1-methylethyl)(2-hydroxy-3,5-di(t-butyl)phenyl)imine
3,5-Di-t-butylsalicylaldehyde (3.00 g) is added to 10 mL of isopropylamine. The solution rapidly turns bright yellow. After stirring at ambient temperature for 3 hours, volatiles are removed under vacuum to yield a bright yellow, crystalline solid (97 percent yield).
b) Preparation of (bis-(1-methylethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)immino) zirconium dibenzyl
A solution of (1-methylethyl)(2-hydroxy-3,5-di(t-butyl)phenyl)imine (605 mg, 2.2 mmol) in 5 mL toluene is slowly added to a solution of Zr(CH2Ph)4 (500 mg, 1.1 mmol) in 50 mL toluene. The resulting dark yellow solution is stirred for 30 min. Solvent is removed under reduced pressure to yield the desired product as a reddish-brown solid.
Catalyst (A6) is bis-(1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)immino) zirconium dibenzyl




The preparation of catalyst (A6) is conducted as follows.
a) Preparation of (1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)imine
2-Methylcyclohexylamine (8.44 mL, 64.0 mmol) is dissolved in methanol (90 mL), and di-t-butylsalicaldehyde (10.00 g, 42.67 mmol) is added. The reaction mixture is stirred for three hours and then cooled to −25° C. for 12 hrs. The resulting yellow solid precipitate is collected by filtration and washed with cold methanol (2×15 mL), and then dried under reduced pressure. The yield is 11.17 g of a yellow solid. 1H NMR is consistent with the desired product as a mixture of isomers.
b) Preparation of bis-(1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)immino)zirconium dibenzyl
A solution of (1-(2-methylcyclohexyl)ethyl)(2-oxoyl-3,5-di(t-butyl)phenyl)imine (7.63 g, 23.2 mmol) in 200 mL toluene is slowly added to a solution of Zr(CH2Ph)4 (5.28 g, 11.6 mmol) in 600 mL toluene. The resulting dark yellow solution is stirred for 1 hour at 25° C. The solution is diluted further with 680 mL toluene to give a solution having a concentration of 0.00783 M.
Catalyst (A7) is (t-butylamido)dimethyl(3-N-pyrrolyl-1,2,3,3a,7a-η-inden-1-yl)silanetitanium dimethyl prepared substantially according to the techniques of U.S. Pat. No. 6,268,444:




Catalyst (A8) is (t-butylamido)di(4-methylphenyl)(2-methyl-1,2,3,3a,7a-η-inden-1-yl)silanetitanium dimethyl prepared substantially according to the teachings of US-A-2003/004286:




Catalyst (A9) is (t-butylamido)di(4-methylphenyl)(2-methyl-1,2,3,3a,8a-η-s-indacen-1-yl)silanetitanium dimethyl prepared substantially according to the teachings of US-A-2003/004286:




Catalyst (A10) is bis(dimethyldisiloxane)(indene-1-yl)zirconium dichloride available from Sigma-Aldrich:




Cocatalyst 1 A mixture of methyldi(C14-18 alkyl)ammonium salts of tetrakis(pentafluorophenyl)borate (here-in-after armeenium borate), prepared by reaction of a long chain trialkylamine (ArmeenTM M2HT, available from Akzo-Nobel, Inc.), HCl and Li[B(C6F5)4], substantially as disclosed in U.S. Pat. No. 5,919,983, Ex. 2.
Cocatalyst 2 Mixed C14-18 alkyldimethylammonium salt of bis(tris(pentafluorophenyl)-alumane)-2-undecylimidazolide, prepared according to U.S. Pat. No. 6,395,671, Ex. 16.
Shuttling Agents The shuttling agents employed include diethylzinc (DEZ, SA1), di(1-butyl)zinc (SA2), di(n-hexyl)zinc (SA3), triethylaluminum (TEA, SA4), trioctylaluminum (SA5), trimethylgallium (SA6), bis(t-butyldimethylsiloxy)i-butylaluminum (SA7), bis(di(trimethylsilyl)amido)isobutylaluminum (SA8), di(2-pyrridylmethoxy)n-octylaluminum (SA9), bis(n-octadecyl)i-butylaluminum (SA10), bis(di(n-pentyl)amido)isobutylaluminum (SA11), bis(2,6-di-t-butylphenoxy)n-octylaluminum (SA 12), di(1-naphthyl)ethylamido)n-octylaluminum (SA13), bis(t-butyldimethylsiloxy)ethylaluminum (SA14), bis(di(trimethylsilyl)amido)ethyl-aluminum (SA 15), bis(2,3,6,7-dibenzoazacyclohexan-1-yl)ethylaluminum (SA16), bis(2,3,6,7-dibenzoazacyclohexan-1-yl)n-octylaluminum (SA17), bis(dimethyl(t-butyl)siloxyl)n-octyl-aluminum (SA18), ethyl(2,6-diphenylphenoxy)zinc (SA19), and ethyl(t-butoxy)zinc (SA20).
General High Throughput Parallel Polymerization Conditions
Polymerizations are conducted using a high throughput, parallel polymerization reactor (PPR) available from Symyx technologies, Inc. and operated substantially according to U.S. Pat. Nos. 6,248,540, 6,030,917, 6,362,309, 6,306,658, and 6,316,663. Ethylene copolymerizations are conducted at 130° C. and 80 psi (550 kPa) with ethylene on demand using 1.2 equivalents of cocatalyst 2 based on total catalyst used. A series of polymerizations are conducted in a parallel pressure reactor (PPR) comprised of 48 individual reactor cells in a 6×8 array that are fitted with a pre-weighed glass tube. The working volume in each reactor cell is 6000 μL. Each cell is temperature and pressure controlled with stirring provided by individual stirring paddles. The monomer gas and quench gas (air) are plumbed directly into the PPR unit and controlled by automatic valves. Liquid reagents are robotically added to each reactor cell by syringes and the reservoir solvent is mixed alkanes. The order of addition is mixed alkanes solvent (4 ml), ethylene, 1-octene comonomer (143 mg), 0.419 μmol cocatalyst, shuttling agent in the indicated amounts, and finally, 0.3495 μmol catalyst A3. After quenching, the reactors are cooled and the glass tubes are unloaded. The tubes are transferred to a centrifuge/vacuum drying unit, and dried for 12 hours at 60° C. The tubes containing dried polymer are weighed and the difference between this weight and the tare weight gives the net yield of polymer. Results are contained in Table 1.
Catalyst/Shuttling Agent Selection Method 1
A series of ethylene/1-octene polymerizations are conducted using differing monomer conversions and one of two potential chain shuttling agents, t-butyldimethylsiloxydi(isopropyl) aluminum (TSA, Runs A-F) and diethylzinc (DEZ, Runs 1-6), using the foregoing high-throughput polymerization technique. The resulting polymers are measured for molecular weight (Mw and Mn) using GPC. Polydispersity Index (PDI=Mw/Mn) is calculated for each polymer. Results are tabulated in Table 1












TABLE 1





Run
Conversion (%)
Yield
Mw (g/mol)
Mn (g/mol)
Mw/Mn




















A
25
0.052
495,202
159,079
3.11


B
51
0.086
455,178
103,781
4.39


C
75
0.102
490,448
210,174
2.33


D
100
0.131
510,722
260,894
1.96


E
150
0.194
871,458
194,801
4.47


F
184
0.235
605,453
137,957
4.39


1
26
0.0589
8,908
6,477
1.38


2
52
0.0852
12,393
9,592
1.29


3
77
0.1173
16,570
13,176
1.26


4
101
0.1416
21,387
17,397
1.23


5
151
0.1923
29,187
23,715
1.23


6
200
0.2752
41,043
32,203
1.27









It may be seen the polymers produced in Runs 1-6 have a relatively narrow polydispersity (Mw/Mn) compared to polymers in the series A-F. This indicates that DEZ is an effective chain shuttling agent under the conditions of the polymerization, whereas TSA is not. Polymers prepared in a reactor, especially a loop, semi-batch, or plug flow type reactor, in a manner to expose an active catalyst site to at least two different sets of reaction conditions, especially conditions encompassing differences in monomer/comonomer ratio, would therefore generate polymer products having multiple blocks or segments (pseudo-block copolymers). These polymers would be expected to possess properties resembling pure block copolymers and distinguishable from those of random copolymers of similar gross comonomer content.
Catalyst/Shuttling Agent Selection Method 2
The previously disclosed high throughput polymerization conditions are substantially repeated using various catalysts, cocatalyst 1, and potential shuttling agents. Ethylene pressure is increased to 200 psi (1.4 MPa). Over 500 reactions are performed. The resulting ethylene/1-octene copolymers are tested for Mn and PDI and polymer production rate compared to rates obtained from a control using MMAO in place of the shuttling agent. The best compositions are then selected based on a combination of greatest molecular weight (Mn) reduction, greatest reduction in PDI, and least reduction (or actual increase) in polymerization rate. Selected combinations showing the best results (ranked by Mn reduction) are presented in Table 2.












TABLE 2







Shuttling





Run
Catalyst
Agent
Relative Mn
Relative PDI
Relative rate







i
A1
SA7
0.07
0.88
1.33


ii
′′
SA5
0.18
0.85
0.57


iii
′′
SA15
0.19
0.93
6.29


iv
A2
SA19
0.27
0.73
0.18


v
A3
SA2
0.29
0.80
9.74


vi
′′
SA8
0.38
1.01
1.15


vii
′′
SA7
0.60
1.06
1.38


viii
′′
SA11
0.65
1.04
1.43


ix
′′
SA3
0.65
0.86
4.61


x
′′
SA17
0.66
0.95
6.36


xi
′′
SA20
0.68
0.82
4.37


xii
A4
SA9
0.52
1.12
2.32


xiii
′′
SA7
0.53
1.07
0.91


xiv
′′
SA11
0.59
1.11
2.47


xv
′′
SA14
0.69
1.07
2.12


xvi
′′
SA18
0.69
1.10
3.16


xvii
′′
SA12
0.70
1.07
0.97


xviii
′′
SA5
0.93
0.95
0.81


xix
A5
SA2
0.29
0.92
0.71


xx
′′
SA13
0.59
0.97
0.93


xxi
′′
SA3
0.63
0.95
0.93


xxii
′′
SA5
0.79
1.10
1.19


xxiii
A6
SA13
0.83
0.92
0.67


xxiv
A7
SA6
0.63
0.96
0.66


xv
′′
SA7
0.74
1.15
0.96


xvi
D1
SA14
0.54
1.10
1.14


xvii
′′
SA10
0.59
1.10
0.77


xviii
′′
SA5
0.74
1.01
0.72


xix
′′
SA16
0.82
1.05
2.62









By reference to Table 2 a suitable combinations of catalyst and shuttling agent may be selected. It is to be emphasized that preferred catalyst/shuttling agent combinations may in different embodiments, be selected based on a desired objective, such as maximum reduction in Mn or improvement in production rate coupled with more modest Mn reduction. Additionally, the above results are based on a batch reactor, whereas in practice, the effect, if any, of using continuous polymerization conditions must also be considered in selecting the final combination of catalysts and shuttling agent(s).
Continuous Solution Polymerization Reactions
Polymer samples according to the invention and comparative polymer examples are prepared in a solution loop reactor using mixed alkanes solvent. Propylene, ethylene, hydrogen, catalyst package, and polymer are dissolved in the solvent during the polymerization process. Following the polymerization, the catalyst system is deactivated with water. The resulting polymer is separated from the solvent by flashing, or devolatilization, of the solvent. The recovered solvent/propylene mixture is condensed, purified, and recycled to the reactor, operating substantially according to the teachings of U.S. Pat. No. 6,355,741, 5,977,251 or 5,684,097.
Referring to FIG. 2, the reactor 30, comprises a closed loop of high pressure piping such as a 3′′ (7.5 cm) diameter, schedule 80 carbon steel pipe equipped with a circulation pump, 32, which circulates the reactor contents (solvent, monomers, catalyst, and polymer) through the piping and associated heat exchangers, 34a and 34b, flow meter, 36, and static mixing elements, 38a, 38b and 38c. In operative communication with the reactor are inlets 52, for injection of monomer(s) and optionally hydrogen, 54, for injection of catalyst, 56, for injection of cocatalyst and optionally chain transfer agent, and 58, for injection of monomer(s), recycled process solvent (comprising unreacted monomer or comonomer), and optionally hydrogen. Reactor outlet, 50, serves as a port for removal of the reactor contents and is in operative communication with a polymer recovery zone (not shown). After exiting the reactor, polymer is separated from process solvent and unreacted monomers in the recovery zone. Recovered process solvent and unreacted monomer is reinjected into the reactor at inlets 52 or 58, or optionally in varying amounts at both to provide ratios of recycled monomer at the two inlets from 1:99 to 99:1.
During operation, the ethylene and propylene concentrations in different sections of the reactor are varied to create inhomogeneous concentrations or gradients of monomer and comonomer within the reactor. This gradient is established by adjustments to pumping rate, reactor feed splits, changing of monomer and commoner injection points, and monomer conversions. For example, ethylene is added at a separate injection point from the fresh comonomer addition point in order to create separate regions of differing concentrations of the two monomers. The amount of recycled process solvent injected with the ethylene may also be minimized in order to maximize the monomer/comonomer molar ratio near the injection point of the reactor. In certain experiments, reduced pumping rates are also employed to decrease reactor mixing and maximize ethylene inhomogeneity within the loop reactor.
For the comparative examples, no chain shuttling agent is employed in combination with a poorly mixed reactor to create blends of polymers having higher and lower crystallinity contents. For the examples according to the invention, a chain shuttling agent is added. The chain shuttling agent creates a fraction of polymer molecules containing segments of polymer made in both ethylene rich and ethylene poor regions of the reactor. In one embodiment of the invention, the chain shuttling agent is injected near to the point of lowest ethylene concentration, thereby resulting in the generation of a higher concentration of polymer in which the chain ends comprise higher crystallinity (low ethylene content) polymer. Results are provided in Tables 3, 4 and 5.
Examples 1-6
Comparative Examples A-B
Examples 1-6 and comparative examples A and B are carried out with the following reagents and conditions: catalyst A1, cocatalyst 1, chain shuttling agent, SA1 (DEZ), polymerization temperature, 105° C., reactor pressure, 540 psig (3.7 MPa), total solvent flow, 1003 pounds/hour (455 kg/hr), propylene conversion, 64 percent, solution density, 41 lb/ft3 (656 kg/m3), and percent solids in reactor, 19 percent. Additional process details are as follows:
Comparative A. The reactor is configured with all the ethylene entering the reactor at one point. No chain shuttling agent is employed. An 8 percent ethylene content propylene/ethylene copolymer is prepared having a melt flow rate of approximately 8 dg/min.
Example 1
Chain shuttling agent SA1 is introduced into the reactor while maintaining the reactor at a constant log(viscosity) the same as for the 8MFR resin produced in Comparative A and discontinuing hydrogen addition. The resulting resin, on hydrolysis of the feed stream, exhibits a MFR of approximately 14. The discrepancy between measured reactor viscosity or molecular weight and ultimate product molecular weight indicates the presence of some fraction of (polymer)2Zn species in the reactor, thereby indicating that chain shuttling is occurring in the reactor.
Example 2
The reaction conditions of Example 1 are altered by reducing the flow of chain shuttling agent until a product having a melt flow rate of 8 dg/min is obtained.
Example 3
The reaction conditions of Example 2 are altered by reducing the pumping rate to maximize the ethylene gradient in the reactor while still ensuring that the reactor contents remained soluble in the diluent. The other flows are maintained as in example 2. The resulting polymer has a measured MFR of approximately 5.
Example 4
The reaction conditions of Example 3 are altered by increasing the flow of chain shuttling agent until a product having a measured melt flow rate of approximately 8 is again obtained.
Example 5
The reaction conditions of Example 4 are altered by increasing the ethylene flow to produce a target polymer comprising approximately 15 percent polymerized ethylene. The chain shuttle agent flow is maintained at the same level but the hydrogen flow to the reactor is increased in order to maintain a product having approximately 8 MFR.
Example 6
The reaction conditions of Example 5 are altered by increasing ethylene flow thereby producing a product having an ethylene content of approximately 20 percent.
Comparative B. The reaction conditions of Example 6 are altered by stopping the flow of chain shuttling agent and increasing hydrogen flow in order to produce a copolymer having a MFR of approximately 8 dg/min. while maintaining an ethylene content of 20 percent.







TABLE 3







Process Conditions





















Fresh
Fresh
Total













propylene
ethylene
propylene

Fresh H2
Log
Catalyst
Catalyst
Cocat.
Cocat.
SA
SA



feed
feed
feed
Split feed
flow
viscosity
concentration
flow
conc.
flow
conc.
flow
Recycle


Ex.
(pph)
(pph)
(pph)
(top/bottom)
(pph)
(logCp)
(ppm Hf))
(pph)
(ppm)
(pph)
(ppm Zn)
(pph)
ratio























A*
201
16.59
285
85/25
2061
2.79
521
1.40
8598
0.63
0
0
9.90


1
′′
17.47
286
′′
0
2.82
′′
2.49
′′
1.11
5500
2.00
9.75


2
′′
17.50
283
′′
′′
3.02
′′
2.52
′′
1.13
′′
1.77
9.80


3
′′
17.49
284
′′
′′
3.27
′′
2.24
′′
1.00
′′
1.57
7.80


4
′′
′′
283
′′
′′
3.02
490
2.34
′′
0.98
5000
1.92
′′


5
178
30.18
260
72/28
1002
3.01
′′
1.61
8598
0.68
′′
1.33
7.70


6
162
40.29
244
62/38
2212
2.90
′′
1.32
7659
0.62
′′
1.09
′′


B*
′′
40.21
240
′′
4458
2.85
′′
0.94
′′
0.45
0
0
7.60





Feed split top/bottom, refers to the percentage of propylene injected in the form of recycled solvent/propylene mixture (bottom number).













TABLE 4





Polymer Physical Properties

























Ethylene
Density
MFR
Tc
Tm
ΔH
Cryst.
Mw
Mw/


Ex.
Content (percent)
(g/cm3)
(dg/min)
(° C.)
(° C.)
(J/g)
(%)
(×103)
Mn





A*
 8
0.8792
9.5
68
121
55
33
209
2.4


1
′′
0.8791
14.9
62
120
54
33
179
2.5


2
′′
0.8795
9.3
61
118
53
32
201
2.5


3
′′
0.9793
5.5
67
127
54
33
227
2.4


4
′′
0.8806
9.0
67
130
55
33
202
2.5


5
15
0.8692
7.9
47
110
32
20
193
2.5


6
20
0.8625
8.8
28
93
20
12
175
2.4


B*
20
0.8623
9.4
22
95
20
12
190
1.9






















23° C.
23° C.




Flex
2% Secant
Load at
Elongation
1 Cycle 300%
Compress.
Blocking



Modulus
Modulus
Break
at Break
Recovery
Set
Strength


Ex.
(MPa)
(MPa)
(MPa)
(percent)
(percent)
(percent)
(KPa)





A*
175
152
30
830
—
—
—


1
178
155
28
850
—
—
—


2
166
141
24
721
—
—
—


3
179
155
27
802
—
—
—


4
189
158
27
842
—
—
—


5
41
30
17
1069
67
34
0


6
19
11
7
1,187
70
41
3


B*
29
15
5
900
56
60
6
















TABLE 5







Polymer Optical Properties















45° Gloss
Internal





Ex.
Clarity (%)
(%)
Haze (%)
clarity
gloss
haze
















A*
75
57
23
0.5167
0.3911
1.2


1
75
63
12
0.3742
0.1414
0.1923


2
75
62
12
0.6148
0.3209
0.2588


3
75
63
12
0.7266
0.1516
0.2345


4
75
60
15
0.5495
0.3033
0.2588


5
76
61
15
0.2915
0.4615
0.614


6
80
63
12
0.3781
1.215
0.2168


B*
68
54
33
0.3701
0.9899
0.3781

## Claims

1. A single reactor continuous process for the polymerization of one or more addition polymerizable monomers to form a polymer comprising multiple regions or segments having differentiated polymer compositions or properties, said process comprising:
contacting an addition polymerizable monomer or mixture of monomers under addition polymerization conditions with a composition comprising a single olefin polymerization catalyst, a cocatalyst and a chain shuttling agent; and
forming at least some of the growing polymer chains under differentiated process conditions such that two or more blocks or segments formed within at least some of the resulting polymer are chemically or physically distinguishable

wherein the differentiated process condition is a monomer gradient maintained between at least two regions of the reactor.

2. The process of claim 1 comprising forming a pseudo-block polymer comprising two or more intramolecular regions or segments comprising differing chemical or physical properties and possessing a molecular weight distribution, Mw/Mn, of less than 3.0.

3. The process of claim 2 comprising forming a polymer mixture comprising: (1) an organic or inorganic polymer, and (2) a the pseudo-block polymer.

4. A process according to claim 1 wherein the catalyst comprises a metal complex corresponding to the formula:



wherein:
R11 is selected from alkyl, cycloalkyl, heteroalkyl, cycloheteroalkyl, aryl, and inertly substituted derivatives thereof containing from 1 to 30 atoms not counting hydrogen or a divalent derivative thereof;
T1 is a divalent bridging group of from 1 to 41 atoms other than hydrogen, and
R12 is a C5-20 heteroaryl group containing Lewis base functionality;
M1 is a group 4 metal;
X1 is an anionic, neutral or dianionic ligand group;
x′ is a number from 0 to 5 indicating the number of such X1 groups; and
bonds, optional bonds and electron donative interactions are represented by lines, dotted lines and arrows respectively.

5. A process according to claim 1 wherein the catalyst comprises a metal complex corresponding to the formula:




wherein:
M2 is a metal of Groups 4-10 of the Periodic Table of the elements;
T2 is a nitrogen, oxygen or phosphorus containing group;
X2 is halo, hydrocarbyl, or hydrocarbyloxy;
t is one or two;
x′′ is a number selected to provide charge balance;
and T2 and N are linked by a bridging ligand.

6. The process of claim 2 wherein the pseudo-block copolymer comprises in polymerized form at least one monomer selected from the group consisting of ethylene, propylene and 4-methyl-1-pentene.

7. The process of claim 4 wherein T1 is 1 to 20 atoms other than hydrogen.

8. The process of claim 4 wherein T1 is a mono- or di-C1-20 hydrocarbyl substituted methylene or silane group.

9. The process of claim 4 wherein R12 is pyridin-2-yl- or substituted pyridin-2-yl group or a divalent derivative thereof.

10. The process of claim 4 wherein M1 is hafnium.

11. The process of claim 1 wherein the process is performed in a loop reactor.