Patent Description:
Processability is the ability to economically process and shape a polymer uniformly. Processability involves such elements as how easily the polymer flows, melt strength, and whether or not the extrudate is distortion free. Typical metallocene catalyzed polyethylenes (mPE) are somewhat more difficult to process than low-density polyethylenes (LDPE) made in a high-pressure polymerization process. Generally, mPEs require more motor power and produce higher extruder pressures to match the extrusion rate of LDPEs. Typical mPEs also have lower melt strength which, for example, adversely affects bubble stability during blown film extrusion, and they are prone to melt fracture at commercial shear rates. On the other hand, however, mPEs exhibit superior physical properties as compared to LDPEs.

It is not unusual in the industry to add various levels of an LDPE to an mPE to increase melt strength, to increase shear sensitivity, i.e., to increase flow at commercial shear rates; and to reduce the tendency to melt fracture. However, these blends generally have poor mechanical properties as compared with neat mPE.

Traditionally, metallocene catalysts produce polymers having a narrow molecular weight distribution. Narrow molecular weight distribution polymers tend to be more difficult to process. The broader the polymer molecular weight distribution the easier the polymer is to process. A technique to improve the processability of mPEs is to broaden the products' molecular weight distribution (MWD) by blending two or more mPEs with significantly different molecular weights, or by changing to a polymerization catalyst or mixture of catalysts that produce broad MWD polymers.

In the art specific metallocene catalyst compound characteristics have been shown to produce polymers that are easier to process. For example, <CIT> discusses metallocene catalyst compounds where the ligand is substituted with a substituent having a secondary or tertiary carbon atom to produce broader molecular weight distribution polymers. <CIT> describes the use of a mixture of metallocene catalysts for producing easy processing polymers. <CIT> also addresses the production of polymers having enhanced processability using a metallocene catalyst compound where the ligands are specifically substituted indenyl ligands.

<CIT>) and <CIT>), describe a metallocene catalyst compound represented by the formula LALBMQn, where MQn may be, among other things, zirconium dichloride, and LA and LB may be, among other things, open, acyclic, or fused ring(s) or ring system(s) such as unsubstituted or substituted, cyclopentadienyl ligands or cyclopentadienyl-type ligands, heteroatom substituted and/or heteroatom containing cyclopentadienyl-type ligands. The Q ligands include hydrocarbyl radicals having from <NUM> to <NUM> carbon atoms.

<CIT>"), relates to polymerization catalyst activator compounds that are either neutral or ionic and include a Group <NUM> atom, preferably boron or aluminum, bonded to at least one halogenated or partially halogenated heterocyclic ligand. The publication states that such activator compounds may be used to activate metallocene catalyst compositions. One such catalyst composition is cyclotetramethylenesilyl (tetramethyl cyclopentadienyl) (cyclopentadienyl) zirconium dimethyl ("(C<NUM>H<NUM>) Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM>"). <CIT> relates to activated catalyst systems from substituted dialuminoxane complexes.

The invention is in accordance with the appended claims. This invention relates to polymerization processes utilizing bridged metallocene catalysts for producing polyethylene compositions having improved properties.

Disclosed herein, but not within the scope of the invention, is a polyethylene composition having: <NUM> ≤ g'avg ≤ <NUM>; MFR > (<NUM> x MI(-<NUM>)); and Mw/Mn ≤ <NUM>. The following features may be present.

The polyethylene composition may have one or more of the following features: <NUM> ≤ g'avg ≤ <NUM>; <NUM> ≤ g'avg ≤ about <NUM>; <NUM> ≤ g'avg ≤ about <NUM>; MFR > (<NUM> x MI(-<NUM>)) about <NUM> ≤ Mw/Mn ≤ about <NUM>; <NUM> ≤ g' at a molecular weight of <NUM>,<NUM> ≤ <NUM>; <NUM> ≤ g' at a molecular weight of <NUM>,<NUM> ≤ <NUM>; a T75-T25 value of equal to or lower than about <NUM> (or equal to or lower than <NUM>), wherein T25 is the temperature at which <NUM>% of the eluted polymer is obtained and T75 is the temperature at which <NUM>% of the eluted polymer is obtained; an MI ≤ about <NUM>, or ≤ about <NUM>, or ≤ about <NUM>; an MFR of about <NUM>-<NUM> at an MI of about <NUM>; a melt strength of < <NUM> cN; a density of <NUM>-<NUM>/cc or <NUM>-<NUM>/cc; and a strain hardening index of greater than <NUM>, or greater than <NUM>, or about <NUM> to about <NUM>.

The composition may comprise as monomers ethylene, an olefin monomer having from <NUM> to <NUM> carbon atoms, and optionally one or more other olefin monomers having from <NUM> to <NUM> carbon atoms such as hexene or butene. The composition may comprise as monomers ethylene and butene. The composition may comprise as monomers ethylene, butene, and another olefin monomer having from <NUM> to <NUM> carbon atoms.

Also disclosed herein, but not within the scope of the invention is a film comprising a polyethylene composition described herein. The film may have one or more of the following features: an MD plastic shrink tension ≤ about <NUM>. 08MPa; an area Retromat shrinkage > <NUM>%; a clarity ≥ <NUM> %; a normalized internal haze ≤ <NUM> %/<NUM> (<NUM> %/mil); a haze < <NUM>%, or < <NUM>%; or < <NUM>%.

Also disclosed herein, but not within the scope of the invention is a film comprising a polyethylene composition, the film having a haze < <NUM> %; a clarity ≥ about <NUM>%; the polyethylene composition having: <NUM> ≤ g'avg ≤ <NUM> and an MFR > (<NUM>. 011x MI(-<NUM>)). Such a film may have one of both of the following features: an Mw/Mn ≤ <NUM>; and an MFR > (<NUM> x MI(-<NUM>)).

Also disclosed herein, but not within the scope of the invention is a film comprising a low density polyethylene composition, the film having: an area Retromat shrinkage > <NUM>%; an MD plastic tension < about <NUM> MPa; a haze < <NUM>%; and a clarity ≥ <NUM>%.

In an aspect of the invention, there is provided a gas phase process for polymerizing olefin(s) to produce the polyethylene composition described herein comprising contacting the olefin(s), under polymerization conditions, with a catalyst system comprising an achiral cyclic bridged metallocene catalyst compound and an activator. The catalyst compound is (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM>. The support may comprise silica. The activator comprises alumoxane, a modified alumoxane, or a mixture thereof. The activator may comprise methylaluminoxane (MAO), modified methylaluminoxane (MMAO), or a combination thereof. The activator may comprise methylaluminoxane (MAO). The activator may comprise methylaluminoxane (MAO) and the support may comprise silica. The catalyst system may be formed by first combining the MAO and the silica, and then by adding thereto the (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM>. The process may be a continuous gas phase process. The comonomer/monomer ratio ratio by mol % used in the process may be < <NUM>.

A composition as described herein may be used, alone or in a blend, in a monolayer or multilayer structure, in one of the following applications, by way of example: shrink sleeve, label application, shrink-wrap, shrink bundling, green house, heavy duty bag, food packaging, injection molding, blow molding, and sheeting.

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention.

Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein:.

Before the present compounds, components, compositions, and/or methods are disclosed and described, it is to be understood that unless otherwise indicated this invention is not limited to specific compounds, components, compositions, reactants, reaction conditions, ligands, metallocene structures, or the like, as such may vary, unless otherwise specified. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

It must also be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless otherwise specified. Thus, for example, reference to "a leaving group" as in a moiety "substituted with a leaving group" includes more than one leaving group, such that the moiety may be substituted with two or more such groups. Similarly, reference to "a halogen atom" as in a moiety "substituted with a halogen atom" includes more than one halogen atom, such that the moiety may be substituted with two or more halogen atoms, reference to "a substituent" includes one or more substituents, reference to "a ligand" includes one or more ligands, and the like.

As used herein, all reference to the<NPL>) (reproduced there with permission from IUPAC).

Generally, metallocene-type or metallocene catalyst compounds include half and full sandwich compounds having one or more bonded to at least one metal atom. Typical metallocene compounds are generally described as containing one or more ligand(s) and one or more leaving group(s) bonded to at least one metal atom. In one preferred embodiment, at least one is η-bonded to a metal atom, most preferably η<NUM>-bonded to the metal atom.

The legends are generally represented by one or more open, acyclic, or fused ring(s) or ring system(s) or a combination thereof. These, preferably ring(s) or ring system(s) are typically composed of atoms selected from Groups <NUM> to <NUM> atoms of the Periodic Table of Elements, preferably the atoms are selected from the group consisting of carbon, nitrogen, oxygen, silicon, sulfur, phosphorous, boron, aluminum, and hydrogen, or a combination thereof. Most preferably the ring(s) or ring system(s) are composed of carbon atoms such as but not limited to those cyclopentadienyl ligands or cyclopentadienyl-type ligand structures or other similar functioning ligand structure such as a pentadiene, a cyclooctatetraendiyl or an imide ligand. The metal atom is preferably selected from Groups <NUM> through <NUM> and the lanthanide or actinide series of the Periodic Table of Elements. Preferably the metal is a transition metal from Groups <NUM> through <NUM>, more preferably <NUM>, <NUM> and <NUM>, and most preferably the metal is from Group <NUM>.

According to the invention the metallocene catalyst is cyclotetramethylenesilyl(tetramethyl cyclopentadienyl)(cyclopentadienyl)zirkonium dimethyl. Further achiral cyclic bridged metallocene catalysts are described but not according to the invention. The metallocene catalyst compounds described herein are represented by the formula:.

where M is a metal atom from the Periodic Table of the Elements and may be a Group <NUM> to <NUM> metal or from the lanthanide or actinide series of the Periodic Table of Elements, preferably M is a Group <NUM>, <NUM> or <NUM> transition metal, more preferably M is a Group <NUM> transition metal, even more preferably M is zirconium, hafnium or titanium. The , LA and LB, are open, acyclic, or fused ring(s) or ring system(s) such as unsubstituted or substituted, cyclopentadienyl ligands or cyclopentadienyl-type ligands, heteroatom substituted and/or heteroatom containing cyclopentadienyl-type ligands. Non-limiting examples of include cyclopentadienyl ligands, indenyl ligands, benzindenyl ligands, fluorenyl ligands, octahydrofluorenyl ligands, cyclooctatetraendiyl ligands, azenyl ligands, azulene ligands, pentalene ligands, phosphoyl ligands, pyrrolyl ligands, pyrozolyl ligands, carbazolyl ligands, borabenzene ligands and the like, including hydrogenated versions thereof, for example tetrahydroindenyl ligands. In one embodiment, LA and LB may be any other ligand structure capable of η-bonding to M, preferably η<NUM>-bonding to M, and most preferably η<NUM>-bonding to M. In another embodiment, LA and LB may comprise one or more heteroatoms, for example, nitrogen, silicon, boron, germanium, sulfur and phosphorous, in combination with carbon atoms to form an open, acyclic, or preferably a fused, ring or ring system, for example, a hetero-cyclopentadienyl ancillary ligand. Other LA and LB ligands include but are not limited to amides, phosphides, alkoxides, aryloxides, imides, carbolides, borollides, porphyrins, phthalocyanines, corrins and other polyazomacrocycles. Independently, each LA and LB may be the same or different type of ligand that is bonded to M.

Independently, each LA and LB may be unsubstituted or substituted with a combination of substituent groups R. Non-limiting examples of substituent groups R include one or more from the group selected from hydrogen, or linear, branched alkyl radicals, or alkenyl radicals, alkynyl radicals, cycloalkyl radicals or aryl radicals, acyl radicals, aroyl radicals, alkoxy radicals, aryloxy radicals, alkylthio radicals, dialkylamino radicals, alkoxycarbonyl radicals, aryloxycarbonyl radicals, carbomoyl radicals, alkyl- or dialkylcarbamoyl radicals, acyloxy radicals, acylamino radicals, aroylamino radicals, straight, branched or cyclic alkylene radicals, or combination thereof. Non-limiting examples of alkyl substituents R include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl, cyclohexyl, benzyl or phenyl groups and the like, including all their isomers, for example tertiary butyl, isopropyl, and the like. Other hydrocarbyl radicals include fluoromethyl, fluroethyl, difluroethyl, iodopropyl, bromohexyl, chlorobenzyl and hydrocarbyl substituted organometalloid radicals including trimethylsilyl, trimethylgermyl, methyldiethylsilyl and the like; and halocarbyl-substituted organometalloid radicals including tris(trifluoromethyl)-silyl, methyl-bis(difluoromethyl)silyl, bromomethyldimethylgermyl and the like; and disubstitiuted boron radicals including dimethylboron for example; and disubstituted pnictogen radicals including dimethylamine, dimethylphosphine, diphenylamine, methylphenylphosphine, chalcogen radicals including methoxy, ethoxy, propoxy, phenoxy, methylsulfide and ethylsulfide. Non-hydrogen substituents R include the atoms carbon, silicon, boron, aluminum, nitrogen, phosphorous, oxygen, tin, sulfur, germanium and the like, including olefins such as but not limited to olefinically unsaturated substituents including vinyl-terminated ligands, for example but-<NUM>-enyl, prop-<NUM>-enyl, hex-<NUM>-enyl and the like. Also, at least two R groups, preferably two adjacent R groups, are joined to form a ring structure having from <NUM> to <NUM> atoms selected from carbon, nitrogen, oxygen, phosphorous, silicon, germanium, aluminum, boron or a combination thereof. Also, a substituent group R group such as <NUM>-butanyl may form a carbon sigma bond to the metal M.

Other ligands may be bonded to the metal M, such as at least one leaving group Q. For the purposes of this patent specification and appended claims the term "leaving group" is any ligand that can be abstracted from a metallocene catalyst compound to form a metallocene catalyst cation capable of polymerizing one or more olefin(s). In one embodiment, Q is a monoamine labile ligand having a sigma-bond to M. Depending on the oxidation state of the metal, the value for n is <NUM>, <NUM> or <NUM> such that formula (I) above represents a neutral metallocene catalyst compound. Non-limiting examples of Q ligands include weak bases such as amines, phosphine, ethers, carboxylates, dienes, hydrocarbyl radicals having from <NUM> to <NUM> carbon atoms, hydrides or halogens and the like or a combination thereof. In another embodiment, two or more Q's form a part of a fused ring or ring system. Other examples of Q ligands include those substituents for R as described above and including cyclobutyl, cyclohexyl, heptyl, tolyl, trifluromethyl, tetramethylene, pentamethylene, methylidene, methyoxy, ethyoxy, propoxy, phenoxy, bis(N-methylanilide), dimethylamide, dimethylphosphide radicals and the like.

The bridged metallocene catalyst compounds disclosed herein include those of formula (I) where LA and LB are bridged to each other by a cyclic bridging group, A. For the purposes of this patent application and appended claims, the cyclic bridging group A comprises, in addition to hydrogen, greater than <NUM> non-hydrogen atoms, preferably greater than <NUM> carbon atoms forming a ring or ring system about at least one other Group <NUM> to <NUM> atom. Non-limiting examples of Group <NUM> to <NUM> atoms include at least one of a carbon, oxygen, nitrogen, silicon, boron, germanium and tin atom or a combination thereof. In a preferred embodiment, the cyclic bridging group A contains a carbon, silicon or germanium atom, most preferably A contains at least one silicon atom. The atoms forming the ring system of A may be substituted with substituents as defined above for R.

Non-limiting examples of cyclic bridging groups A include cyclo-tri or tetra-alkylene silyl or include cyclo-tri or tetra-alkylene germyl groups, for example, cyclotrimethylenesilyl group or cyclotetramethylenesilyl group.

Other examples of cyclic bridging groups are represented by the following structures:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In a preferred embodiment, (but not according to the invention) the metallocene catalyst compounds include cyclotrimethylenesilyl(tetramethyl cyclopentadienyl)(cyclopentadienyl)zirconium dichloride, cyclotetramethylenesilyl(tetramethyl cyclopentadienyl)(cyclopentadienyl)zirconium dichloride, cyclotrimethylenesilyl (tetramethyl cyclopentadienyl)(<NUM>-methyl indenyl)zirconium dichloride, cyclotrimethylenesilyl(tetramethyl cyclopentadienyl)(<NUM>-methyl cyclopentadienyl)zirconium dichloride, cyclotrimethylenesilyl bis(<NUM>-methyl indenyl)zirconium dichloride, cyclotrimethylenesilyl(tetramethyl cyclopentadienyl)(<NUM>,<NUM>,<NUM>-trimethyl cyclopentadienyl) zirconium dichloride, and cyclotrimethylenesilyl bis(tetra methyl cyclopentadienyl) zirconium dichloride. According to the invention the metallocene catalyst compound is cyclotetramethylenesily(tetramethyl cyclopentadienyl)(cyclopentadienyl) zirconium dimethyl.

Also described herein, herein, the metallocene catalyst compound is represented by the formula:.

(C<NUM>H<NUM>-dRd)(R'AxR')(C<NUM>H<NUM>-dRd)M Qg-<NUM>     (II).

where M is a Group <NUM>, <NUM>, <NUM> transition metal, (C<NUM> H<NUM>-d Rd) is an unsubstituted or substituted, cyclopentadienyl ligand or cyclopentadienyl-type ligand bonded to M, each R, which can be the same or different, is hydrogen or a substituent group containing up to <NUM> non-hydrogen atoms or substituted or unsubstituted hydrocarbyl having from <NUM> to <NUM> carbon atoms or combinations thereof, or two or more carbon atoms are joined together to form a part of a substituted or unsubstituted ring or ring system having <NUM> to <NUM> carbon atoms, R'AxR' is a cyclic bridging group, where A is one or more of, or a combination of carbon, germanium, silicon, tin, phosphorous or bridging two (C<NUM> H<NUM>-d Rd) rings, and the two R"s form a cyclic ring or ring system with A; more particularly, non-limiting examples of cyclic bridging group A may be represented by R'<NUM>C,R'<NUM>Si,R'<NUM>Ge,R'P, and R'B(E), where E is a Lewis base such as phosphine or amine, where the two R"s are joined to form a ring or ring system. In one embodiment, R' is a hydrocarbyl containing a heteroatom, for example boron, nitrogen, oxygen or a combination thereof The two R"s may be independently, hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, hydrocarbyl-substituted organometalloid, halocarbyl-substituted organometalloid, where the two R''s may be joined to form a ring or ring system having from <NUM> to <NUM> non-hydrogen atoms, preferably from <NUM> to <NUM> carbon atoms; and independently, each Q can be the same or different is a hydride, substituted or unsubstituted, linear, cyclic or branched, hydrocarbyl having from <NUM> to <NUM> carbon atoms, halogen, alkoxides, aryloxides, amides, phosphides, or any other univalent anionic ligand or combination thereof, also, two Q's together may form an alkylidene ligand or cyclometallated hydrocarbyl ligand or other divalent anionic chelating ligand, where g is an integer corresponding to the formal oxidation state of M, and d is an integer selected from <NUM>, <NUM>, <NUM>, <NUM> or <NUM> and denoting the degree of substitution, x is an integer from <NUM> to <NUM>.

In one embodiment, the cyclic bridged metallocene catalyst compounds are those where the R substituents on the ligands LA and LB, (C<NUM>H<NUM>-dRd) of formulas (I) and (II) are substituted with the same or different number of substituents on each of the ligands. In another embodiment, the ligands LA and LB, (C<NUM>H<NUM>-dRd) of formulas (I) and (II) are different from each other.

In a preferred embodiment, the ligands of the metallocene catalyst compounds of formula (I) and (II) are asymmetrically substituted. In another preferred embodiment, at least one of the ligands LA and LB, (C<NUM>H<NUM>-dRd) of formulas (I) and (II) is unsubstituted.

In a preferred embodiment, the ligands of the cyclic bridged metallocene catalyst compounds are achiral.

Other metallocene catalysts compounds described herein include cyclic bridged heteroatom, mono-ligand metallocene-type compounds. These types of catalysts and catalyst systems are described in, for example, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>, <CIT>,<CIT>, <CIT>, <CIT>, <CIT> and <CIT>, and <CIT>. Other metallocene catalyst compounds and catalyst systems useful in the invention may include those described in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>,<CIT>, <CIT>, <CIT>,<CIT>, <CIT>and <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

In another embodiment disclosed herein, the cyclic bridged metallocene catalyst compound is represented by the formula:.

where M is a Group <NUM> to <NUM> metal atom or a metal selected from the Group of actinides and lanthanides of the Periodic Table of Elements, preferably M is a Group <NUM> to <NUM> transition metal, and more preferably M is a Group <NUM>, <NUM> or <NUM> transition metal, and most preferably M is a Group <NUM> transition metal in any oxidation state, especially titanium; LC is a substituted or unsubstituted ligand bonded to M; J is bonded to M; A is bonded to L and J; J is a heteroatom ancillary ligand; and A is a cyclic bridging group; Q is a univalent anionic ligand; and n is the integer <NUM>,<NUM> or <NUM>. In formula (III) above, LC, A and J form a fused ring system. In an embodiment, LC of formula (III) is as defined above for LA in formula (I), and A, M and Q of formula (III) are as defined above in formula (I).

In another embodiment disclosed herein the metallocene catalyst compound is represented by the formula:.

(C<NUM> H<NUM>-y-xRx)(R"AyR")(JR'z-<NUM>-y)M(Q)n(L')w     (IV).

where M is a transition metal from Group <NUM> in any oxidation state, preferably, titanium, zirconium or hafnium, most preferably titanium in either a +<NUM>, +<NUM> or +<NUM> oxidation state. A combination of compounds represented by formula (IV) with the transition metal in different oxidation states is also contemplated. Lc is represented by (Cs H<NUM>-y-xRx) and is a ligand as described above. For purposes of formula (IV) RO means no substituent. More particularly (C<NUM> H<NUM>-y-xRx) is a cyclopentadienyl ring or cyclopentadienyl-type ring or ring system which is substituted with from <NUM> to <NUM> substituent groups R, and "x" is <NUM>, <NUM>, <NUM>, <NUM> or <NUM> denoting the degree of substitution. Each R is, independently, a radical selected from a group consisting of <NUM> to <NUM> non-hydrogen atoms. More particularly, R is a hydrocarbyl radical or a substituted hydrocarbyl radical having from <NUM> to <NUM> carbon atoms, or a hydrocarbyl-substituted metalloid radical where the metalloid is a Group <NUM> or <NUM> element, preferably silicon or nitrogen or a combination thereof, and halogen radicals and mixtures thereof. Substituent R groups also include silyl, germyl, amine, and hydrocarbyloxy groups and mixtures thereof. Also, in another embodiment, (C<NUM>H<NUM>-y-xRx) is a cyclopentadienyl ligand in which two R groups, preferably two adjacent R groups are joined to form a ring or ring system having from <NUM> to <NUM> atoms, preferably from <NUM> to <NUM> carbon atoms. This ring system may form a saturated or unsaturated polycyclic cyclopentadienyl-type ligand such as those ligands described above, for example, indenyl, tetrahydroindenyl, fluorenyl or octahydrofluorenyl.

The (JR'z-<NUM>-y) of formula (IV) is a heteroatom containing ligand in which J is an element with a coordination number of three from Group <NUM> or an element with a coordination number of two from Group <NUM> of the Periodic Table of Elements. Preferably, J is a nitrogen, phosphorus, oxygen or sulfur atom with nitrogen being most preferred. Each R' is, independently, a radical selected from the group consisting of hydrocarbyl radicals having from <NUM> to <NUM> carbon atoms, or as defined for R in formula (I) above; the "y" is <NUM> to <NUM>, preferably <NUM> to <NUM>, most preferably y is <NUM>, and the "z" is the coordination number of the element J. In one embodiment, in formula (IV), the J of formula (III) is represented by (JR'z-<NUM>-y).

In formula (IV) each Q is, independently, any univalent anionic ligand such as halogen, hydride, or substituted or unsubstituted hydrocarbyl having from <NUM> to <NUM> carbon atoms, alkoxide, aryloxide, sulfide, silyl, amide or phosphide. Q may also include hydrocarbyl groups having ethylenic or aromatic unsaturation thereby forming a η<NUM>bond to M. Also, two Q's may be an alkylidene, a cyclometallated hydrocarbyl or any other divalent anionic chelating ligand. The integer n may be <NUM>, <NUM>, <NUM> or <NUM>.

The (R"AyR") of formula (IV) is a cyclic bridging group where A is a Group <NUM> to <NUM> element, preferably a Group <NUM> and <NUM> element, most preferably a Group <NUM> element. Non-limiting examples of A include one or more of, or a combination of carbon, silicon, germanium, boron, nitrogen, phosphorous, preferably at least one silicon atom. The two R"'s for a ring or ring system about A, the two R"s together having from <NUM> to <NUM> non-hydrogen atoms, preferably from <NUM> to <NUM> carbon atom.

Optionally associated with formula (IV) is L', a Lewis base such as diethylether, tetraethylammonium chloride, tetrahydrofuran, dimethylaniline, aniline, trimethylphosphine, n-butylamine, and the like; and w is a number from <NUM> to <NUM>. Additionally, L' may be bonded to any of R, R' or Q and n is <NUM>, <NUM>, <NUM> or <NUM>.

The above described cyclic bridged metallocene catalyst compounds are can be activated with an activator comprising an aluminoxane or the product of an aluminoxane and a support or carrier. This activation yields catalyst compounds capable of polymerizing olefins.

It is well known in the art that aluminoxanes contain a broad distribution of structures formed from the reaction of R"3Al or mixtures of R"3Al, where R" is hydrogen or a similar or different hydrocarbyl, with water. This is in contrast with dialuminoxanes which have a specific structure. It is also well recognized that aluminoxanes may contain alanes, R"3Al, remaining from an incomplete hydrolysis reaction.

The above described cyclic bridged metallocene catalyst compounds are typically activated in various ways to yield catalyst compounds having a vacant coordination site that will coordinate, insert, and polymerize olefin(s).

For the purposes of this patent specification and appended claims, the term "activator" is defined to be any compound or component or method which can activate any of the metallocene catalyst compounds of the invention as described above. Non-limiting activators, for example may include a Lewis acid or a non-coordinating ionic activator or ionizing activator or any other compound including Lewis bases, aluminum alkyls, conventional-type cocatalysts or an activatorsupport and combinations thereof that can convert a neutral metallocene catalyst compound to a catalytically active metallocene cation. It is within the scope of this invention to use alumoxane or modified alumoxane as an activator, and/or to also use ionizing activators, neutral or ionic, such as tri (n-butyl)ammonium tetrakis(pentafluorophenyl)boron or a trisperfluorophenyl boron metalloid precursor or a trisperfluoronaphtyl boron metalloid precursor that would ionize the neutral metallocene catalyst compound.

In one embodiment, an activation method using ionizing ionic compounds not containing an active proton but capable of producing both a metallocene catalyst cation and a non-coordinating anion are also contemplated, and are described in <CIT>, <CIT> and <CIT>.

There are a variety of methods for preparing alumoxane and modified alumoxanes, non-limiting examples of which are described in <CIT>, <CIT>,<CIT>, <CIT>, <CIT>, <CIT>,<CIT>, <CIT>,<CIT>,<CIT>,<CIT>, <CIT>, <CIT>,<CIT>,<CIT>, <CIT>, <CIT>, <CIT>,<CIT>, <CIT><CIT>, <CIT>, <CIT> and <CIT>, and <CIT>.

Ionizing compounds may contain an active proton, or some other cation associated with but not coordinated to or only loosely coordinated to the remaining ion of the ionizing compound. Such compounds and the like are described in <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>, <CIT>,<CIT>, <CIT>, <CIT>, <CIT>,<CIT> and <CIT>, and <CIT>.

Other activators include those described in <CIT> such as tris (<NUM>, <NUM>', <NUM>"-nonafluorobiphenyl)fluoroaluminate. Combinations of activators are also contemplated by the invention, for example, alumoxanes and ionizing activators in combinations, see for example, <CIT> and <CIT>, and <CIT> and <CIT>. <CIT> describes activating metallocene catalyst compounds with perchlorates, periodates and iodates including their hydrates. <CIT> and <CIT> describe the use of lithium (<NUM>,<NUM>'-bisphenyl-ditrimethylsilicate). 4THF as an activator for a metallocene catalyst compound. Also, methods of activation such as using radiation (see <CIT>), electrochemical oxidation, and the like are also contemplated as activating methods for the purposes of rendering the neutral metallocene catalyst compound or precursor to a metallocene-type cation capable of polymerizing olefins.

It is further contemplated by the invention that other catalysts can be combined with the cyclic bridged metallocene catalyst compounds. For example, see <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

In another embodiment of the invention one or more metallocene catalyst compounds or catalyst systems may be used in combination with one or more conventional-type or other advanced catalyst compounds or catalyst systems. Non-limiting examples of mixed catalysts and catalyst systems are described in <CIT>, <CIT>,<CIT>,<CIT>,<CIT>, <CIT>, <CIT>, <CIT>, <CIT>,<CIT>and <CIT>, and <CIT>.

The above described cyclic metallocene catalyst compounds and catalyst systems may be combined with one or more support materials or carriers using one of the support methods well known in the art or as described below. In the preferred embodiment, the method of the invention uses a polymerization catalyst in a supported form. For example, in a most preferred embodiment, a metallocene catalyst compound or catalyst system is in a supported form, for example deposited on, bonded to, contacted with, or incorporated within, adsorbed or absorbed in, or on, a support or carrier.

The terms "support" or "carrier" are used interchangeably and are any support material, preferably a porous support material, for example, talc, inorganic oxides and inorganic chlorides. Other carriers include resinous support materials such as polystyrene, functionalized or crosslinked organic supports, such as polystyrene divinyl benzene polyolefins or polymeric compounds, zeolites, clays, or any other organic or inorganic support material and the like, or mixtures thereof.

The preferred carriers are inorganic oxides that include those Group <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> metal oxides. The preferred supports include silica, alumina, silica-alumina, magnesium chloride, and mixtures thereof. Other useful supports include magnesia, titania, zirconia, montmorillonite (<CIT>) and the like. Also, combinations of these support materials may be used, for example, silicachromium, silica-alumina, silica-titania and the like.

It is preferred that the carrier, most preferably an inorganic oxide, has a surface area in the range of from about <NUM> to about <NUM><NUM>/g, pore volume in the range of from about <NUM> to about <NUM> cc/g and average particle size in the range of from about <NUM> to about <NUM>. More preferably, the surface area of the carrier is in the range of from about <NUM> to about <NUM><NUM>/g, pore volume of from about <NUM> to about <NUM> cc/g and average particle size of from about <NUM> to about <NUM>. Most preferably the surface area of the carrier is in the range is from about <NUM> to about <NUM><NUM>/g, pore volume from about <NUM> to about <NUM> cc/g and average particle size is from about <NUM> to about <NUM>. The average pore size of the carrier of the invention typically has pore size in the range of from <NUM> to <NUM>Å, preferably <NUM> to about <NUM>Å, and most preferably <NUM> to about <NUM>Å.

Examples of supporting the metallocene catalyst systems are described in <CIT>, <CIT>, <CIT>, <CIT>,<CIT>, <CIT>, <CIT>,<CIT>, <CIT>,<CIT>, <CIT>,<CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>,<CIT>,<CIT>, <CIT>, <CIT>, <CIT>,<CIT>, <CIT>, <CIT>,<CIT>, <CIT> and <CIT>, <CIT> and Serial No. <CIT>, and <CIT>, <CIT>, <CIT> and <CIT>.

In one embodiment, the cyclic bridged metallocene catalyst compounds may be deposited on the same or separate supports together with an activator, or the activator may be used in an unsupported form, or may be deposited on a support different from the supported metallocene catalyst compounds, or any combination thereof.

There are various other methods in the art for supporting a polymerization catalyst compound or catalyst system. For example, the cyclic bridged metallocene catalyst compound may contain a polymer bound ligand as described in <CIT> and <CIT>, the metallocene catalyst system may be spray dried as described in <CIT>, the support used with the cyclic bridged metallocene catalyst system is functionalized as described in <CIT>, or at least one substituent or leaving group is selected as described in <CIT>.

In a preferred embodiment, the disclosure provides for a supported cyclic bridged metallocene catalyst system that includes an antistatic agent or surface modifier that is used in the preparation of the supported catalyst system as described in <CIT>. The catalyst systems can be prepared in the presence of an olefin, for example hexene-<NUM>.

A preferred method for producing the supported cyclic bridged metallocene catalyst system is described below and is described in <CIT> and <CIT>. In this preferred method, the cyclic bridged metallocene catalyst compound is slurried in a liquid to form a metallocene solution and a separate solution is formed containing an activator and a liquid. The liquid may be any compatible solvent or other liquid capable of forming a solution or the like with the cyclic bridged metallocene catalyst compounds and/or activator. In the most preferred embodiment the liquid is a cyclic aliphatic or aromatic hydrocarbon, most preferably toluene. The cyclic bridged metallocene catalyst compound and activator solutions are mixed together and added to a porous support or the porous support is added to the solutions such that the total volume of the metallocene catalyst compound solution and the activator solution or the metallocene catalyst compound and activator solution is less than four times the pore volume of the porous support, more preferably less than three times, even more preferably less than two times; preferred ranges being from <NUM> times to <NUM> times range and most preferably in the <NUM> to <NUM> times range. Another preferred method is to pre-react the porous support with an activator in a hydrocarbon diluent. The hydrocarbon solution of the cyclic bridged metallocene is added later to complete the catalyst preparation.

Procedures for measuring the total pore volume of a porous support are well known in the art. Details of one of these procedures are discussed in <NPL>). This preferred procedure involves the use of a classical BET apparatus for nitrogen absorption. Another method well known in the art is described in <NPL>).

The mole ratio of the metal of the activator component to the metal of the supported cyclic bridged metallocene catalyst compounds are in the range of between <NUM>:<NUM> to <NUM>:<NUM>, preferably <NUM>:<NUM> to <NUM>:<NUM>, and most preferably <NUM>:<NUM> to <NUM>:<NUM>. Where the activator is an ionizing activator such as those based on the anion tetrakis(pentafluorophenyl)boron, the mole ratio of the metal of the activator component to the metal component of the cyclic bridged metallocene catalyst is preferably in the range of between <NUM>:<NUM> to <NUM>:<NUM>. Where an unsupported cyclic bridged metallocene catalyst system is utilized, the mole ratio of the metal of the activator component to the metal of the cyclic bridged metallocene catalyst compound is in the range of between <NUM>:<NUM> to <NUM>,<NUM>:<NUM>, preferably <NUM>:<NUM> to <NUM>:<NUM>, and most preferably <NUM>:<NUM> to <NUM>:<NUM>.

In a preferred embodiment, the catalyst system comprises a catalyst as described herein activated by methylaluminoxane (MAO) and supported by silica. While conventionally, MAO is combined with a metallocene and then the combination is deposited on silica, as shown in the examples, the preference herein is to first combine the activator (e.g. MAO) and the support (e.g. silica) and then to add the catalyst to the combination. Modified MAO (MMAO) or a combination of MAO and MMAO may also be used. In a preferred embodiment, the catalyst compound comprises (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM>.

In one embodiment of the invention, olefin(s), preferably C<NUM> to C<NUM> olefin(s) or alpha-olefin(s), preferably ethylene or propylene or combinations thereof are prepolymerized in the presence of the cyclic bridged metallocene catalyst system prior to the main polymerization. The prepolymerization can be carried out batchwise or continuously in gas, solution or slurry phase including at elevated pressures. The prepolymerization can take place with any olefin monomer or combination and/or in the presence of any molecular weight controlling agent such as hydrogen. For examples of prepolymerization procedures, see <CIT>,<CIT>, <CIT>, <CIT>,<CIT> and <CIT>, <CIT>, and <CIT>.

In one embodiment the polymerization catalyst is used in an unsupported form, preferably in a liquid form such as described in <CIT> and <CIT>, and <CIT>. The polymerization catalyst in liquid form can be fed to a reactor as described in <CIT>.

In one embodiment, the cyclic bridged metallocene catalysts of the disclosure can be combined with a carboxylic acid salt of a metal ester, for example aluminum carboxylates such as aluminum mono, di- and tri- stearates, aluminum octoates, oleates and cyclohexylbutyrates, as described in <CIT>.

The catalysts and catalyst systems of the disclosure described above are suitable for use in any polymerization process over a wide range of temperatures and pressures. The temperatures may be in the range of from -<NUM> to about <NUM>, preferably from <NUM> to about <NUM>, and the pressures employed may be in the range from <NUM> atmosphere to about <NUM> atmospheres or higher.

Polymerization processes include solution, gas phase, slurry phase and a high pressure process or a combination thereof. Particularly preferred is a gas phase or slurry phase polymerization of one or more olefins at least one of which is ethylene or propylene.

The process of this invention is directed toward a gas phase polymerization process of olefin monomers having from <NUM> to <NUM> carbon atoms, preferably <NUM> to <NUM> carbon atoms, and more preferably <NUM> to <NUM> carbon atoms. The invention is particularly well suited to the polymerization of two or more olefin monomers of ethylene, propylene, butene-<NUM>, pentene-<NUM>, <NUM>-methyl-pentene-<NUM>, hexene-<NUM>, octene- <NUM> and decene-<NUM>. According to the invention the olefin monomers comprise ethylene and butene.

Other monomers useful in the process of the invention include ethylenically unsaturated monomers, diolefins having <NUM> to <NUM> carbon atoms, conjugated or nonconjugated dienes, polyenes, vinyl monomers and cyclic olefins. Non-limiting monomers useful in the invention may include norbornene, norbornadiene, isobutylene, isoprene, vinylbenzocyclobutane, styrenes, alkyl substituted styrene, ethylidene norbornene, dicyclopentadiene and cyclopentene.

In a preferred embodiment of the process of the invention, a copolymer of ethylene and butene is produced.

In another embodiment of the process of the invention, ethylene is polymerized with at least two different comonomers, optionally one of which may be a diene, to form a terpolymer. Two of the three monomers of the terpolymer are butene and ethylene. In one embodiment, the comonomer content is <NUM> to <NUM> wt%, or <NUM> to <NUM> wt%. As seen in example <NUM> below, the use of (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> as the catalyst in preparing an ethylene/butene copolymer, resulted in a sharp response to comonomer ratio. That is, the melt index (MI) changed quickly and sharply as the comonomer ratio was adjusted. Density changes were also observed. These changes may be associated with long chain branching. Therefore, polymers having ethylene and butene as two of the monomers may be used to control product melt index. Further, products with broad or bimodal distribution in molecular weight or melt index in a single reactor using a single catalyst could be used by changing the comonomer feed in a controlled fashion, thus producing polyethylene products with custom designed properties with single reactor economics.

Disclosed herein but not within the scope of the invention is a polymerization process, particularly a gas phase or slurry phase process, for polymerizing propylene alone or with one or more other monomers including ethylene, and/or other olefins having from <NUM> to <NUM> carbon atoms. Polypropylene polymers may be produced using the particularly bridged metallocene catalysts as described in <CIT>and <CIT>.

Typically in a gas phase polymerization process, a continuous cycle is employed where in one part of the cycle of a reactor system, a cycling gas stream, otherwise known as a recycle stream or fluidizing medium, is heated in the reactor by the heat of polymerization. This heat is removed from the recycle composition in another part of the cycle by a cooling system external to the reactor. Generally, in a gas fluidized bed process for producing polymers, a gaseous stream containing one or more monomers is continuously cycled through a fluidized bed in the presence of a catalyst under reactive conditions. The gaseous stream is withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, polymer product is withdrawn from the reactor and fresh monomer is added to replace the polymerized monomer. (See for example <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>,<CIT>, <CIT>,<CIT>, <CIT> and<CIT>.

The reactor pressure in a gas phase process may vary from about <NUM> kPa (<NUM> psig) to about <NUM> kPa (<NUM> psig), preferably in the range of from about <NUM> kPa (<NUM> psig) to about <NUM> kPa (<NUM> psig), more preferably in the range of from about <NUM> kPa (<NUM> psig) to about <NUM> kPa (<NUM> psig).

The reactor temperature in a gas phase process may vary from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>, more preferably in the range of from about <NUM> to <NUM>, and most preferably in the range of from about <NUM> to about <NUM>.

Typical polymerization conditions are set forth in Table <NUM>.

Other gas phase processes contemplated by the process of the invention include those described in <CIT>, <CIT> and <CIT>, and <CIT>, <CIT> and <CIT>.

In a preferred embodiment, the reactor utilized in the present invention is capable and the process of the invention is producing greater than <NUM> (<NUM> lbs) of polymer per hour (<NUM>/hr) to about <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr) or higher of polymer, preferably greater than <NUM>/hr (<NUM> lbs/hr), more preferably greater than <NUM>/hr (<NUM>,<NUM> lbs/hr), even more preferably greater than <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr), still more preferably greater than <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr), still even more preferably greater than <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr) and most preferably greater than <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr) to greater than <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr).

A slurry polymerization process (not according to the invention) generally uses pressures in the range of from about <NUM> to about <NUM> atmospheres and even greater and temperatures in the range of <NUM> to about <NUM>. In a slurry polymerization, a suspension of solid, particulate polymer is formed in a liquid polymerization diluent medium to which ethylene and comonomers and often hydrogen along with catalyst are added. The suspension including diluent is intermittently or continuously removed from the reactor where the volatile components are separated from the polymer and recycled, optionally after a distillation, to the reactor. The liquid diluent employed in the polymerization medium is typically an alkane having from <NUM> to <NUM> carbon atoms, preferably a branched alkane. The medium employed should be liquid under the conditions of polymerization and relatively inert. When a propane medium is used the process must be operated above the reaction diluent critical temperature and pressure. Preferably, a hexane or an isobutane medium is employed.

A preferred polymerization technique not within the scope of the invention is referred to as a particle form polymerization, or a slurry process where the temperature is kept below the temperature at which the polymer goes into solution. Such technique is well known in the art, and described in for instance <CIT>. Other slurry processes include those employing a loop reactor and those utilizing a plurality of stirred reactors in series, parallel, or combinations thereof. Non-limiting examples of slurry processes include continuous loop or stirred tank processes. Also, other examples of slurry processes are described in <CIT>.

In an embodiment not within the scope of the invention the reactor used in the slurry process disclosed herein is capable of and the process is producing greater than <NUM> (<NUM> lbs) of polymer per hour (<NUM>/hr), more preferably greater than <NUM>/hr (<NUM> lbs/hr), and most preferably greater than <NUM>/hr (<NUM>,<NUM> lbs/hr). In another embodiment the slurry reactor used in the process is producing greater than <NUM> (<NUM>,<NUM> lbs) of polymer per hour (<NUM>/hr), preferably greater than <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr) to about <NUM>,<NUM>/hr (<NUM>,<NUM> lbs/hr).

Examples of solution processes are described in <CIT>, <CIT>,<CIT> and<CIT>.

A preferred process of the invention is where the process, a gas phase process is operated in the presence of a metallocene catalyst system and in the absence of or essentially free of any scavengers, such as triethylaluminum, trimethylaluminum, triisobutylaluminum and tri-n-hexylaluminum and diethyl aluminum chloride, dibutyl zinc and the like. This preferred process is described in <CIT> and <CIT> and <CIT>. In another preferred embodiment of the process of the invention, the process is operated by introducing a benzyl compound into the reactor and/or contacting a benzyl compound with the metallocene catalyst system of the invention prior to its introduction into the reactor.

The properties of the polymers were determined by the test methods listed in Table <NUM> or described herein.

Long chain branching index (LCB or g'avg) and g' are described in <CIT>.

Polymers of the instant disclosure may have enhanced optical and shrinkage properties, as discussed further below.

The polymers produced by a process of an embodiment of the invention can be used in a wide variety of products and end-use applications. The polymers produced include linear low-density polyethylene, plastomers, high-density polyethylenes, low-density polyethylenes, polypropylene and polypropylene copolymers. The polymers may be made up of, at least partially, butene, ethylene, and other olefin monomers having from <NUM> to <NUM> carbon atoms. The polymers are copolymers of butene and ethylene, or terpolymers of butene, ethylene, and other olefin monomer.

The polymers, typically ethylene based polymers, have a density in the range of from <NUM>/cc to <NUM>/cc, preferably in the range of from <NUM>/cc to <NUM>/cc, more preferably in the range of from <NUM>/cc to <NUM>/cc, even more preferably in the range of from <NUM>/cc to <NUM>/cc, yet even more preferably in the range from <NUM>/cc to <NUM>/cc, and most preferably greater than <NUM>/cc to about <NUM>/cc. The melt strength of the polymers produced using the catalyst of the disclosure are preferably greater than <NUM> cN, preferably greater than <NUM> cN and, preferably less than <NUM> cN. For purposes of this patent application and appended claims melt strength is measured with a capillary rheometer (RHEO-TESTER™ <NUM>, Goettfert, Rock Hill, SC) in conjunction with the Goettfert Rheotens melt strength apparatus (RHEOTENS™ <NUM>). A polymer melt strand extruded from the capillary die is gripped between two counter-rotating wheels on the apparatus. The take-up speed is increased at a constant acceleration of <NUM>/sec<NUM>, which is controlled by the WinRHEO™ program provided by Goettfert. The maximum pulling force (in the unit of cN) achieved before the strand breaks or starts to show draw-resonance is determined as the melt strength. The temperature of the rheometer is set at <NUM>. The barrel has a diameter of <NUM>. The capillary die has a length of <NUM> and a diameter of <NUM>. The polymer melt is extruded from the die at a piston speed of <NUM>/sec. The apparent shear rate for the melt in the die is, therefore, <NUM> sec-<NUM> and the speed at die exit is <NUM>/sec. The distance between the die exit and the wheel contact point should be <NUM>. Polymers of embodiments of the instant disclosure have a combination of exceptionally high shear thinning for extrusion, outstanding film optical property and excellent shrink performance. Historically HD-LDPE is the only product family having most of these attributes. However, the clarity of HP-LDPE is far inferior to polymers of embodiments of the instant disclosure. Conventional ZN-LLDPE are lacking of most of these attributes. Some easy process (i.e., very broad MWD) products from gas phase and/or slurry processes, are typically very poor in optical properties. The shrink property of these conventional products is also somewhat insufficient for shrink application. (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> was found to be very effective in reducing the film haze of various LLDPE (especially for a polymer made using (<NUM>,<NUM>-Me, n-Bu-Cp)<NUM>ZrCl<NUM> as the catalyst and for a polymer made using (C<NUM>H<NUM>-CH<NUM>CH<NUM>CH<NUM>)<NUM>Hf(CH<NUM>)<NUM>.

As shown in <FIG>, polymers of embodiments of the instant disclosure exhibited strain-hardening behavior under the transient uniaxial extensional flow, similar to HP-LDPE. As shown in Table <NUM>, polymers of embodiments of the instant disclosure have broad MFR (over <NUM>), which is an indicator of good processability. The films from these products have TD shrinkage comparable to or better than HP-LDPE, optical properties similar to HP-LDPE and dart impact strength significantly better than HP-LDPE and LLDPE. Compared with a high-pressure ethylene polymerization process, a gas phase reactor also has the added benefit of lower cost and, in general, higher capacity.

The strain hardening at <NUM> of Comparative Example A (ExxonMobil LD103. <NUM>, from Exxon Mobil Chemical Company, Houston, TX) and Reference Example <NUM> are respectively shown in <FIG> and <FIG>. The following two references discuss strain hardening of polyolefins and the test for measuring the same: "<NPL>); and <NPL>).

The RETRAMAT shrink test used herein is based on NFT <NUM>-<NUM> and ASTM D <NUM>-<NUM>, procedure A. Methods DIN <NUM>-<NUM> and ISO/DIS <NUM> only cover the shrink force measurement, but do not give guidelines on the simultaneous measurement of shrink percentages. The ASTM method covers the determination of the plastic shrink tension and related shrink characteristics shrink force and orientation release stress of heat-shrinkable film of less than <NUM> thickness, while the specimen is totally restrained from shrinking as it is heated. The NFT <NUM>-<NUM> method covers the total shrinking process, being both the plastic and the thermal shrink process.

The method used herein consists of exposing two film samples to a given temperature, during a given time, and to cool them down at room temperature, simulating what happens inside a shrinkage installation. For each test sample, a minimum of <NUM> strips off <NUM> length and <NUM> width are prepared for both MD and TD on a sample cutter. Retramat stickers are applied onto the sample edges so that the shrink area of the test specimen measures exactly <NUM> in length. The oven temperature is <NUM> and the closing duration is <NUM> seconds. During the test, one of the samples is connected to a force transducer, while the other is connected to a displacement transducer. A thermocouple allows following up the temperature at a few millimetres from the middle of the sample. The <NUM> parameters (force - displacement - temperature) are continuously displayed on the Retramat and recorded on a lab PC.

The polymers produced by the process of the invention may have a molecular weight distribution, a weight average molecular weight to number average molecular weight (Mw/Mn) of greater than <NUM> to about <NUM>, particularly greater than <NUM> to about <NUM>, more preferably greater than about <NUM> to less than about <NUM>, and most preferably from <NUM> to <NUM>.

In one preferred embodiment, the polymers of the present disclosure have a Mz/Mw of greater than or equal to <NUM>, preferably greater than <NUM>. M, is the z-average molecular weight. In another preferred embodiment, the polymers of the disclosure have a Mz/Mw of greater than or equal to <NUM> to about <NUM>. In yet another preferred embodiment, the Mz/Mw is in the range greater than <NUM> to less than <NUM>.

The polymers of the present disclosure in one embodiment have a melt index (MI) or (<NUM><NUM>) as measured by ASTM-D-<NUM>-E in the range from <NUM> dg/min to <NUM> dg/min, more preferably from about <NUM> dg/min to about <NUM> dg/min, even more preferably from about <NUM> dg/min to about <NUM> dg/min, even more preferably from about <NUM> dg/min to about <NUM> dg/min, and most preferably from about <NUM> dg/min to about <NUM> dg/min.

The polymers of the disclosure in an embodiment have a melt index ratio (I<NUM>/<NUM><NUM>) (<NUM><NUM> is measured by ASTM-D-<NUM>-F) equal to or greater than <NUM> x MI(-<NUM>); more preferably equal to or greater than <NUM> x MI(-<NUM>); as shown in <FIG>.

In certain embodiments, the polymers as described herein may have a narrow composition distribution characterized in that the T75-T25 value is lower than <NUM>, preferably lower than <NUM>, more preferably lower than <NUM>, and most preferably lower than <NUM>, wherein T25 is the temperature at which <NUM>% of the eluted polymer is obtained and T75 is the temperature at which <NUM>% of the eluted polymer is obtained in a TREF experiment as described herein. The TREF-LS data reported herein were measured using an analytical size TREF instrument (Polymerchar, Spain), with a column of the following dimension: inner diameter (ID) <NUM> and outer diameter (OD) <NUM> and a column length of <NUM>. The column was filled with steel beads. <NUM> of a <NUM>% (w/v) polymer solution in orthodichlorobenzene (ODCB) containing <NUM> BHT/<NUM> were charged onto the column and cooled from <NUM> to <NUM> at a constant cooling rate of <NUM>/min. Subsequently, ODCB was pumped through the column at a flow rate of <NUM>/min, and the column temperature was increased at a constant heating rate of <NUM>/min to elute the polymer.

As shown below in Table <NUM>, films of embodiments of the disclosure possess good optical and shrinkage properties. For instance, the films may have one or more of the following properties: an MD plastic shrink tension < about <NUM>. 08MPa; an area Retromat shrinkage > <NUM>%; a clarity ≥ <NUM> %; a normalized internal haze ≤ <NUM> %/<NUM> (<NUM> %/mil); a haze < <NUM>%; a haze < <NUM>%; and a haze < <NUM>%.

The polymers of the disclosure may be blended and/or coextruded with any other polymer. Non-limiting examples of other polymers include linear low density polyethylenes produced via conventional Ziegler-Natta and/or metallocene catalysis, elastomers, plastomers, high pressure low density polyethylene, high density polyethylenes, polypropylenes and the like.

Polymers produced by the process of the invention and blends thereof are useful in such forming operations as film, sheet, and fiber extrusion and coextrusion as well as blow molding, injection molding and rotary molding. Films include blown or cast films formed by monolayer extrusion, coextrusion or by lamination useful as shrink sleeves, shrink wrap, bundle shrink, cling film, stretch film, sealing films, oriented films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, medical packaging, industrial liners, membranes, etc. in food-contact and non-food contact applications. Fibers include melt spinning, solution spinning and melt blown fiber operations for use in woven or non-woven form to make filters, diaper fabrics, medical garments, geotextiles, etc. Extruded articles include medical tubing, wire and cable coatings, geomembranes, and pond liners. Molded articles include single and multi-layered constructions in the form of bottles, tanks, large hollow articles, rigid food containers and toys, etc..

It is to be understood that while the invention has been described in conjunction with the specific embodiments thereof, the foregoing description is intended to illustrate and not limit the scope of the invention. Other aspects, advantages and modifications will be apparent to those skilled in the art to which the invention pertains.

Therefore, the following examples are put forth so as to provide those skilled in the art with a complete disclosure and description of how to make and use the compounds of the invention, and are not intended to limit the scope of that which the inventors regard as their invention.

In all the examples below, the methylalumoxane (MAO) used was a <NUM> weight percent MAO solution in toluene (typically <NUM> wt % Aluminum and <NUM> wt % MAO by NMR) available from Albemarle Corporation (Baton Rouge, LA). Davison <NUM> silica dehydrated to <NUM> (silica gel) was used and is available from W. Grace, Davison Chemical Division (Baltimore, MD). Anhydrous, oxygenfree solvents were used. The synthesis of (CH<NUM>)<NUM>Si(C<NUM>Me<NUM>(CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrCl<NUM> is described in <CIT>.

A <NUM> solution of methyl lithium and ether (<NUM>, <NUM> mol) was slowly added to a stirred mixture of (CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrCl<NUM> (<NUM>, <NUM> mol) and ether (<NUM>) in a <NUM> flask. After stirring for <NUM>, the ether was slowly removed with a N<NUM> purge then the remaining solids extracted with methylene chloride. The solvent was removed to give the product (<NUM>, <NUM> mol).

A <NUM> beaker was charged with Aluminum stearate (<NUM>) from Crompton Corporation (now Chemtura Corporation, Middlebury, CT), a <NUM> wt % suspension of Snowtex™ IPA-ST-ZL in isopropanol (<NUM>) from Nissan Chemical Industries Inc. (Houston, TX) and methanol (<NUM>). The slurry was stirred at ambient for <NUM> hours then dried to a mud with a nitrogen purge. Vacuum and heat (<NUM>) were applied for two days to remove residual solvent. The solids were crushed and sieved through a No. <NUM> mesh screen to give <NUM> wt % Snowtex™ flow aid (Nissan Chemical Industries Inc. , Houston, TX) as a fine powder.

Crosfield ES757 silica (<NUM>) (INEOS Silicas Limited, Warrington, U. ), dehydrated at <NUM>, was added to a stirred (overhead mechanical conical stirrer) mixture of toluene (<NUM>) and <NUM> wt% solution of methyl aluminoxane in toluene (<NUM>, <NUM> mol). The silica was chased with toluene (<NUM>) then the mixture was heated to <NUM> for <NUM>. Afterwards, volatiles were removed by application of vacuum and mild heat (<NUM>) overnight then the solid was allowed to cool to room temperature. To a stirred slurry of these solids and toluene (<NUM>), was slowly added a solution of (CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> (<NUM>, <NUM> mmol) and toluene (<NUM>) over a <NUM> period. After an additional <NUM>, volatiles were removed by application of vacuum and mild heat (<NUM>) overnight then the solid was allowed to cool to room temperature. This catalyst was dry-blended briefly with a mixture of <NUM> wt% Snowtex™ and <NUM> wt% aluminum stearate (<NUM> wt % total of additive).

Crosfield ES70 silica (<NUM>), (INEOS Silicas Limited, Warrington, U. ), dehydrated at <NUM>, was added to a stirred (overhead mechanical conical stirrer) mixture of toluene (<NUM>) and <NUM> wt% solution of methyl aluminoxane in toluene (<NUM>, <NUM> mol). The silica was chased with toluene (<NUM>) then the mixture was heated to <NUM> for <NUM>. Afterwards, volatiles were removed by application of vacuum and mild heat (<NUM>) overnight, then the solid was allowed to cool to room temperature. To a stirred slurry of these solids and toluene (<NUM>), was slowly added a solution of (CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> (<NUM>, <NUM> mmol) and toluene (<NUM>) over a <NUM> period. After an additional <NUM>, volatiles were removed by application of vacuum and mild heat (<NUM>) overnight then the solid was allowed to cool to room temperature. The solids were dry-blended briefly with <NUM> of a mixture of <NUM> wt% SnowTex and <NUM> wt% aluminum stearate.

In a typical procedure, silica (<NUM>), dehydrated at <NUM>, was added to a stirred (overhead mechanical conical stirrer) mixture of toluene (<NUM>) and <NUM> wt% solution of methyl aluminoxane in toluene (<NUM>, <NUM> mol). The silica was chased with toluene (<NUM>) then the mixture was heated to <NUM> for <NUM>. Afterwards, volatiles were removed by application of vacuum and mild heat (<NUM>) overnight then the solid was allowed to cool to room temperature.

To a slurry of <NUM> mmol/g methyl aluminoxane supported on Davison <NUM> silica, dehydrated at <NUM>, (<NUM>) and pentane (<NUM>) stirred with an overhead stirrer, was slowly added a solution of (CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> (<NUM>, <NUM> mmol) and toluene. After stirring <NUM>, the mixture was filtered and dried.

These catalysts were tested in a continuous fluidized-bed gas-phase reactor with a nominal <NUM> (<NUM>") reactor diameter, an average bed weight of about <NUM>, gas-velocity of about <NUM>/s (<NUM> ft/s), production rate of about <NUM>/h. The reactor was operated at a pressure of <NUM> KPa (<NUM> psig) of which ethylene was <NUM> mol %. The balance of gas was made up with hydrogen, <NUM>-hexene, and nitrogen as indicated in Table <NUM>.

The polymers of Examples <NUM> and <NUM> were prepared from ethylene and butene-<NUM> monomers in a pilot-scale continuous gas phase fluidized bed reactor using CAT A. The reactor was operated at <NUM> and <NUM> KPa (<NUM> psi) ethylene partial pressure. The fluidized bed was made up of polymer granules and the average bed weight was approximately <NUM> to <NUM> (<NUM> to <NUM> lbs). During the reaction, aluminum distearate was added to the reactor as a <NUM> wt % slurry in mineral oil at concentrations on a resin basis from <NUM> and <NUM> ppmw (parts per million weight). The conditions for making polymers of Examples <NUM> and <NUM> are listed in Table <NUM>.

The reactor granules of Examples <NUM> and <NUM> were dry blended with additives before being compounded on a <NUM> (<NUM>") Davis-Standard single-screw extruder equipped with mixing pins and underwater pelletizer at an output rate was approximately <NUM>/hr (<NUM> lb/hr). The compounded pellets of examples <NUM> and <NUM> were then film extruded on a <NUM> (<NUM>") Gloucester line with a <NUM> (<NUM>") oscillating die and an air ring from Future Design Inc. (Mississauga, Ontario, Canada). The output rate was about <NUM>/hr (<NUM> lbs/hr) (<NUM>/hr (<NUM> lbs/hr)-in die circumference) and the die gap was <NUM> (<NUM> mils). Film gauge was <NUM> (<NUM> mil) and blow up ratio (BUR) varied from <NUM> to <NUM>. Frost line height (FLH) was typically <NUM> to <NUM> (<NUM> to <NUM>"). The die temperature was about <NUM> (<NUM> °F).

Table <NUM> compares the properties of the polymers of Examples <NUM> and <NUM> to the properties of the following reference polymers: Borealis Borstar FB2230 (Borealis A/S, Vienna, Austria). Dow DNDA7340 Cr (The Dow Chemical Company, Midland, MI). Dow DYNH-<NUM> (The Dow Chemical Company, Midland, MI). ExxonMobil LD103. <NUM> (from Exxon Mobil Chemical Company, Houston, TX). The films of reference were made under similar conditions on the same film line.

As shown in this example, a polymer of an embodiment of the invention can improve the optical properties of other LLDPE polymers when it is blended in as a minor component. In this example, a polymer of an embodiment of this invention was blended in at <NUM>% (by weight) of the final product using an on-line blending set-up on a Battenfeld Gloucester (Gloucester, MA ) film line. In this set-up, the blend components were weighted separately according to the blend ratio and added to a mixing chamber, where the components were mixed by agitation before they were discharged into a feed hopper above the extruder. The line was equipped with a <NUM> (<NUM>") single screw extruder, a <NUM> (<NUM>") oscillating die and an air ring from Future Design Inc. (Mississauga, Ontario, Canada). The output rate was <NUM>/hr (<NUM> lbs/hr) (<NUM>/hr (<NUM> lbs/hr)-in dir circumference) and the die gap was <NUM> (<NUM> mil). Film gauge was <NUM> (<NUM> mil) and BUR was held constant at <NUM>. FLH was typically <NUM> to <NUM> (<NUM> to <NUM>"). The die temperature was <NUM>°F. Table <NUM> shows these haze improvements for different blends.

This polymer has a density of <NUM> grams/cc, an MI (I<NUM>) of <NUM> grams/<NUM> and a MFR of <NUM>. It was made using CAT B under similar conditions as Examples <NUM> and <NUM>.

When a polymer of an embodiment of the disclosure is blended into other LLDPE polymers as a minor component, in addition to the benefit of enhancing the base polymer's optical properties, the polymer also improves their TD tear resistance while largely maintains their MD tear resistance unchanged or causes insignificant or small loss. In contrast, when these LLDPEs are blended with HP-LDPE to improve optical properties, the loss in toughness is dramatic. Additionally, blending such polymers also improves the extrusion performance of the base polymers, as indicated by the increase in the specific output (lbs/hp-hr), making the extrusion process more energy efficient.

Polymers were prepared from ethylene (C<NUM>) and butene-<NUM> (C4) monomers in a pilot-scale continuous gas phase fluidized bed reactor using (CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> (CAT A). The reactor was operated at temperatures of <NUM> and <NUM>, and ethylene partial pressures of <NUM> kPa and <NUM> kPa (<NUM> and <NUM> psi). The fluidized bed was made up of polymer granules and the average bed weight was approximately <NUM> to <NUM> (<NUM> to <NUM> lbs). During the reaction, aluminum distearate was added to the reactor as a <NUM> wt % slurry in mineral oil at concentrations on a resin basis from <NUM> and <NUM> ppmw (parts per million weight). The comonomer concentration in the reactor was changed; its effect on product was recorded, and is shown below in Tables <NUM> and <NUM>.

For comparative purpose, a polymer was generated using Me<NUM>Si(H<NUM>In)<NUM>ZrCl<NUM> as the catalyst. The reactor was operating at <NUM> and <NUM> kPa (<NUM> psi) ethylene partial pressure. The comonomer, butene-<NUM>, concentration was changed from approximately <NUM> mol. % to approximately <NUM> mol. %, with other process parameters held constant. The melt flow index (MI or I<NUM>) of the product only changed from approximately <NUM> to <NUM>/<NUM>.

(CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> (CAT A) was used to produce ethylene (C2) and butene-<NUM> (C<NUM>) copolymer in a pilot-scale continuous gas phase fluidized bed reactor. The reactor temperature was at <NUM> and reactor ethylene partial pressure was at approximately <NUM> kPa (<NUM> psi). The comonomer, butene-<NUM>, concentration was changed from approximately <NUM> mol. % to approximately <NUM> mol. %, with other process parameters held constant. Results are shown in Table <NUM>. The melt index (MI or I<NUM>) of the product changed significantly from approximately <NUM> to <NUM>/<NUM>.

This experiment was repeated one more time, also using (CH<NUM>)<NUM>Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> (CAT A) as catalyst, but at somewhat different reactor conditions. The reactor temperature was the same at <NUM>, but the reactor ethylene partial pressure was at <NUM> kPa (<NUM> psi) and the H<NUM>/C<NUM> ratio was at approximately <NUM>. The reactor was steadily making approximately <NUM> (g/<NUM>) Melt Index product for extended period of time before the comonomer, butene-<NUM>, concentration was changed from approximately <NUM> mol. % to approximately <NUM> mol%, with other process parameters held constant. Results are shown in Table <NUM>. The melt index (MI or I<NUM>) of the product changed dramatically from <NUM> to over <NUM>/<NUM>. This level of change is very significant and unexpected from other metallocene catalysts such as Me<NUM>Si(H<NUM>In)<NUM>ZrCl<NUM> given in the comparative example.

When subjected to uniaxial extension, the extensional viscosity of a polymer increases with strain rate. The transient uniaxial extensional viscosity of a linear polymer can be predicted as is known to those skilled in the art. Strain hardening occurs when the polymer is subjected uniaxial extension and the transient extensional viscosity increases more than what is predicted from linear viscoelastic theory. The strain hardening index, as herein defined, is the ratio of the observed to the theoretically predicted transient uniaxial extensional viscosity in the extensional viscosity measurement, i.e. Strain hardening index = ηE+obs(e = <NUM>) / ηE+pre(e = <NUM>).

<FIG> and <FIG> show strain hardening at <NUM> of ethylene/hexene copolymers prepared using a lab-scale gas phase reactor and CAT C as a catalyst (Example <NUM> and <FIG>). This is compared to ExxonMobil LD103. <NUM> (from ExxonMobil Chemical Company, Houston, TX) (<FIG>). The samples were compounded on a Haake Polylab system (Thermo Fisher Scientific, Inc. , Waltham, MA) and blown into films on a Haake-Brabender combination system (Thermo Fisher Scientific, Inc. , Waltham, MA). In <FIG> and <FIG>, the strain, e = <NUM>, is at time <NUM> divided by strain rate. The data for example <NUM> are shown in Table <NUM>.

The polymer exhibits a strain hardening index of greater than <NUM>, or greater than <NUM>, or about <NUM> to about <NUM>.

<FIG> is a graph of MFR v. MI for polymers of embodiments of the instant disclosure (using (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> as the catalyst) and comparative polymers. As seen from this Figure, polymers of embodiments of the instant disclosure satisfy the following relations: MFR > (<NUM> x MI(-<NUM><NUM> ) and MFR > (<NUM> x MI(-<NUM><NUM>)).

<FIG> is a graph of Retramat shrinkage v. MD Plastic Force for films made from polymers of embodiments of the instant disclosure (using (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> as the catalyst) including Examples <NUM> and <NUM>, and comparative films. As seen from this Figure, the films of embodiments of the instant invention generally have an area Retromat shrinkage of greater than <NUM>% and an MD plastic tension of less than about <NUM> MPa.

<FIG> is a graph of g'avg v. molecular weight for polymers of embodiments of the instant disclosure (using (C<NUM>H<NUM>)Si(C<NUM>Me<NUM>)(C<NUM>H<NUM>)ZrMe<NUM> as the catalyst) and comparative polymers. As seen from this Figure, polymers of embodiments of the instant disclosure satisfy the following relations: <NUM> ≤ g' avg ≤ <NUM> and Mw/Mn ≤ <NUM>.

The phrases, unless otherwise specified, "consists essentially of and "consisting essentially of do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, as along as such steps, elements, or materials, do not affect the basic and novel characteristics of the invention, additionally, they do not exclude impurities normally associated with the elements and materials used.

Claim 1:
A gas phase process for polymerizing olefin(s) to produce a polyethylene composition, having
a long chain branching index of <NUM> ≤ g'avg ≤ <NUM>;
a Melt Flow Rate (MFR) of > (<NUM> x MI(-<NUM>)), where MI is Melt Index; and
a weight average molecular weight to number average molecular weight Mw/Mn ≤ <NUM> comprising contacting the olefin(s), under polymerization conditions, with a catalyst system comprising an achiral cyclic bridged metallocene catalyst compound and an activator;
wherein the achiral cyclic bridged metallocene catalyst compound is cyclotetramethylenesilyl(tetramethyl cyclopentadienyl)(cyclopentadienyl) zirconium dimethyl;
wherein the polymer product comprises as monomers ethylene and butene; and wherein the activator comprises alumoxane, a modified alumoxane, or a mixture thereof;
wherein long chain branching index is determined as described in the description; wherein MFR is determined according to ASTM D <NUM>; and
wherein Melt Index is determined is determined according to ASTM D <NUM>-E.