Aryl substituted metallocene catalysts and their use

Substituted metallocenes which have a substituent selected from the group consisting of aryl alkyl, aryl alkyl silyl, and aryl silyl groups, catalyst systems resulting from the combination of such metallocenes and a cocatalyst, and for producing olefins using such catalyst systems.

BACKGROUND OF THE INVENTION
 U.S. Pat. No. 5,324,800 discloses that certain substituted metallocenes
 when used in catalyst systems for producing olefin polymers produce higher
 activity than when one uses an unsubstituted metallocene such as
 bis(cyclopentadienyl)zirconium dichloride. The patent contains the broad
 statement that included among the possible substituents are various
 hydrocarbyl radicals having 1 to 20 carbon atoms. Arylalkyl radicals are
 recited as one example of such hydrocarbyl radicals. There is, however,
 only one arylalkyl substituted metallocene actually named, i.e.
 bis(beta-phenylpropyl cyclopentadienyl) zirconium dimethyl. See column 5,
 lines 23 and 24. Example 4 of the patent might conceivably have used
 bis(beta-phenylpropylcyclopentadienyl) zirconium dichloride; however, even
 that is just an assumption based on the fact that the symbols used in
 Example 4 were the same as those used in connection with the naming of the
 dimethyl metallocene in column 5, lines 23 and 24. From the nomenclature
 used in the patent it is assumed that in both of those metallocenes the
 substituted cyclopentadienyl group was
 1-cyclopentadienyl-2-phenyl-2-methyl-ethane, that is to say that there
 were only two carbons separating tie cyclopentadienyl group and the phenyl
 group. Example 4 of that patent provides some evidence that that
 particular metallocene was slightly more than twice as active as the
 unsubstituted metallocene bis(cyclopentadienyl)zirconium dichloride.
 The present inventors have since prepared the metallocenes
 bis(phenylmethylidene cyclopentadienyl) zirconium dichloride,
 bis(phenylethylidene cyclopentadienyl) zirconium dichloride, and bis
 (phenyl-n-propylidene cyclopentadienyl) zirconium dichloride, which could
 also be called bis(1-phenyl-3-cyclopentadienyl-n-propane) zirconium
 dichloride, and have used those metallocenes with an aluminoxane
 cocatalyst in the polymerization of olefins. It was observed that the
 activity increased as the length of the alkylidene group was increased.
 The first two named metallocenes gave activities that were much less than
 half of the activity of the later. It would therefor be logical to assume
 that the metallocene having the n-propylidene alkylene group connecting
 the phenyl and the cyclopentadienyl was more active than the metallocene
 of Example 4 of the above mentioned patent, said metallocene having only
 two carbons between the phenyl and the cyclopentadienyl rather than 3.
 The applicants also prepared bis(phenyl-isopropylidene-cyclopentadienyl)
 zirconium dichloride, i.e. a metallocene in which the alkylene radical
 connecting the phenyl and the cyclopentadienyl was 1,1-dimethyl methylene.
 That metallocene was of very low activity as compared to that of even
 bis(phenylmethylidene cyclopentadienyl) zirconium dichloride and
 bis(phenylethylidene cyclopentadienyl) zirconium dichloride. The
 metallocene had an activity of only about 5.8 kg of polyethylene per hour
 which is even lower than that reported for the unsubstituted
 cyclopentadienyl metallocene bis(cyclopentadienyl) zirconium dichloride.
 See U.S. Pat. No. 5,780,659 which shows that under substantially the same
 polymerization conditions bis(cyclopentadienyl) zirconium dichloride had
 an activity of about 136 kg of polyethylene per hour.
 The present invention is based in part upon the discovery that different
 aryl alkyl, aryl alkyl silyl, or aryl silyl substituted metallocenes
 produce unexpected effects when used with a cocatalyst in the
 polymerization of olefins.
 Thus an object of the present invention is to provide certain metallocenes
 having unexpected properties. Another object is to provide processes for
 the polymerization of olefins using such metallocenes.
 SUMMARY OF THE INVENTION
 In accordance with the present invention, there is provided new substituted
 metallocenes which have a substituent selected from the group consisting
 of aryl alkyl, aryl alkyl silyl, and aryl silyl groups.
 In accordance with another aspect of the present invention there are
 provided catalyst systems resulting from the combination of such
 metallocenes with a suitable cocatalyst.
 In accordance with yet another aspect of the present invention there is
 provided methods for producing olefins using such catalyst systems.
 DETAILED DESCRIPTION OF THE INVENTION
 In accordance with the present invention there is provided unbridged bis
 metallocenes in which each ligand has the formula
EQU Cp-Si(R).sub.2 --(C(R').sub.2).sub.n -A
 wherein Cp is selected from cyclopentadienyl, 3-methylcyclopentadienyl, and
 1-indenyl, each R can be the same or different and is an alkyl radical
 having 1 to 6 carbon atoms, each R' can be the same or different and is
 selected from hydrogen and alkyl radicals having 1 to 6 carbon atom, A is
 an aryl radical, i.e. a cyclic compound having conjugated unsaturation,
 and is n is 0 to 5 or
EQU Cp--(C(R').sub.2).sub.n -A
 wherein Cp is selected from cyclopentadienyl, 3-methylcyclopentadienyl,
 1-indenyl, A is an aryl radical as defined above, and n is 1 to 5, except
 when Cp is cyclopentadienyl and A is phenyl then R' is not methylene,
 dimethyl methylene, or 2-methyl ethylene which is connected such that the
 phenyl is also bonded to the 2 carbon of the 2-methyl ethylene. Some
 examples of A include phenyl, 4-methylphenyl, 1-indenyl, 9-fluorenyl,
 naphthyl, 4-fluorophenyl, 3,5-dimethylphenyl, and the like.
 The inventive metallocenes are produced by reacting the necessary ligands
 using techniques known in the art. Unbridged mixed metallocenes can be
 prepared by reacting unsubstituted half sandwich cyclodienyl ZrCl.sub.3
 with the lithium salt of a selected aryl substituted cyclodienyl compound.
 For example cyclopentadienyl ZrCl.sub.3 can be reacted with the lithium
 salt of cyclopentadienyl methylidene phenyl to yield the metallocene
 (phenyl methylidene cyclopentadienyl) (cyclopentadienyl) ZrCl.sub.2.
 Aryl substituted cyclodienyl compounds needed to produce the inventive
 metallocenes can be produced by reacting an omega bromo alkyl aryl
 compound or an omega bromo alkyl silyl aryl compound or an omega bromo
 silyl aryl compound with cyclopentadienyl sodium. A similar technique can
 yield aryl substituted fluorenyl compounds. 1-Aryl substituted indenyl
 compounds can be produced by reacting indenyl lithium with aryl
 1-haloalkanes or aryl dialkyl chloro silanes. Aryl indenyl compounds with
 the aryl group attached at the 2 position can be produced by reacting
 2-indanone with omega phenylalkyl magnesium bromide in diethyl ether, then
 hydrolyzing, and finally dehydrogenating using p-toluenesufonic acid.
 The aryl substituted metallocenes can be used for the polymerization. The
 inventive catalyst systems are particularly useful for the polymerization
 of alpha-olefins having 2 to 10 carbon atoms. Examples of such olefins
 include ethylene, propylene, butene-1, pentane-1, 3-methylbutene-1,
 hexene-1, 4-methylpentene-1, 3-methylpentene-1, heptene-1, octene-1,
 decene-1, 4,4-dimethyl-1-pentane, 4,4-diethyl-1-hexene,
 3,4-dimethyl-1-hexene, and the like and mixtures thereof. The catalysts
 are also useful for preparing copolymers of ethylene and propylene and
 copolymers of ethylene or propylene and a higher molecular weight olefin.
 Monomers such as styrene and butadiene are also useful.
 Polymerizations with the inventive catalyst can be carried out under a wide
 range of conditions depending upon the particular metallocene employed and
 the particular results desired. The inventive catalyst systems are
 considered useful for polymerization conducted under solution, slurry, or
 gas phase reaction conditions. Typically the inventive metallocene would
 be used with a suitable cocatalyst.
 Examples of suitable cocatalysts include generally any of those
 organometallic cocatalysts which have in the past been employed in
 conjunction with transition metal containing olefin polymerization
 catalysts. Some typical examples include organometallic compounds of
 metals of Groups IA, IIA, and IIIB of the Periodic Table. Examples of such
 compounds have included organometallic halide compounds, organometallic
 hydrides and even metal hydrides. Some specific examples include
 triethylaluminum, triisobutylaluminum, diethylaluminum chloride,
 diethylaluminum hydride, and the like. Other examples of known cocatalysts
 include the use of a stable non-coordinating counter anion cocatalyst, an
 example of such is disclosed in U.S. Pat. No. 5,155,080, e.g. using
 triphenyl carbenium tetrakis (pentafluorophenyl) boronate. Another example
 would be the use a mixture of triethylaluminum and dimethylfluoroaluminum
 such as disclosed by Zambelli et al, Macromolecules, 22, 2186 (1989). In
 such counter anion systems the cocatalyst can be viewed as an ion-exchange
 compound comprising a cation which will irreversibly react with as least
 one ligand contained in the metallocene and a non-coordination anion which
 is ether a single coordination complex comprising a plurality of
 lipophilic radicals covalently coordinated to and shielding a central
 formally charge-bearing metal or metalloid atom or an anion comprising a
 plurality of boron atoms such as polyhedral boranes, carboranes, and
 metallacarboranes.
 The currently most preferred cocatalyst is an aluminoxane. Such compounds
 include those compounds having repeating units of the formula
 ##STR1##
 where R is generally a hydrocarbyl group having 1 to 5 carbon atoms. The
 organo aluminoxane component used in preparing the inventive solid
 catalyst system include oligomeric aluminum compounds having repeating
 units of the formula
 ##STR2##
 Some examples are often represented by the general formula (--AlR--O).sub.n
 or R(--AlR--O--).sub.n AlR.sup.2. In the general alumoxane formula R is
 preferably a C.sub.1 -C.sub.5 alkyl radical, for example, methyl, ethyl,
 propyl, butyl or pentyl and "n" is an integer from 1 to about 50. Most
 preferably, R is methyl and "n" is at least 4.
 Aluminoxanes can be prepared by various procedures known in the art. For
 example, an aluminum alkyl may be treated with water dissolved in an inert
 organic solvent, or it may be contacted with a hydrated salt, such as
 hydrated copper sulfate suspended in an inert organic solvent, to yield an
 aluminoxane. Generally the reaction of an aluminum alkyl with a limited
 amount of water is postulated to yield a mixture of the linear and cyclic
 species of the aluminoxane. Aluminoxanes, also sometimes referred to as
 poly(hydrocarbyl aluminum oxides) are well known in the art and are
 generally prepared by reacting an hydrocarbylaluminum compound with water.
 Such preparation techniques are disclosed in U.S. Pat. Nos. 3,242,099 and
 4,808,561, the disclosures of which are incorporated herein by reference.
 The currently preferred aluminoxane cocatalysts are prepared either from
 trimethylaluminum or triethylaluminum and are sometimes referred to as
 poly(methyl aluminum oxide) and poly(ethyl aluminum oxide), respectively.
 It is also within the scope of the invention to use an aluminoxane in
 combination with a trialkylaluminum, such as disclosed in U.S. Pat. No.
 4,794,096, the disclosure of which is incorporated herein by reference.
 In a particular preferred embodiment, the inventive metallocene can be
 employed in combination with a solid organoaluminoxane which is
 substantially insoluble in the polymerization diluent under particle form
 polymerization conditions. Such a solid aluminoxane can be prepared by
 contacting a solution of an organoaluminoxane with an organoboroxine under
 conditions sufficient to produce a solid. Another technique for preparing
 an insoluble organoaluminoxane involves contacting a solution of an
 organoaluminoxane with water or an active hydrogen compound as taught in
 U.S. Pat. No. 4,990,640. Still another technique involves contacting a
 dried support such as silica with trimethylaluminum and then adding water
 to form a solid containing pendant aluminoxy groups, such cocatalysts are
 sometimes referred to as partially hydrated trimethylaluminum or PHT for
 short.
 Still another technique of producing a solid cocatalyst involves contacting
 an organoaluminoxane with an organic borane compound free of acidic
 hydrogen as taught U.S. Pat. No. 5,354,721, the disclosure of which is
 incorporated herein by reference. Yet another technique involves
 contacting an organoaluminoxane with an organoboron compound having boron
 acid functionality, i.e.--BOH, as taught in U.S. Pat. No. 5,414,189, the
 disclosure of which is incorporated herein by reference.
 The currently preferred technique for preparing the solid organoaluminoxy
 cocatalyst involves contacting an organic solution of an organoaluminoxane
 optionally containing trialkylaluminums with a suitable organoboroxine
 compound as taught in U.S. Pat. No. 5,411,925, the disclosure of which is
 incorporated herein by reference.
 When the polymerizations are carried out in the presence of liquid diluents
 obviously it is important to use diluents which do not have an adverse
 effect upon the catalyst system. Typical liquid diluents include propane,
 butane, isobutane, pentane, hexane, heptane, octane, cyclohexane,
 methylcyclohexane, toluene, xylene, and the like. Typically the
 polymerization temperature can vary over a wide range, temperatures
 typically would be in a range of about -60.degree. C. to about 300.degree.
 C., more preferably in the range of about 20.degree. C. to about
 160.degree. C. Typically the pressure of the polymerization would be in
 the range of from about 1 to about 500 atmospheres or even greater. The
 inventive catalyst system is particularly useful for polymerizations
 carried out under particle form, i.e., slurry-type polymerization
 conditions.
 The polymers produced with the catalysts herein disclosed have a wide range
 of uses that will be apparent to those skilled in the art from the
 physical properties of the respective polymers. Applications such as
 molding, films, adhesives, and the like are indicated.
 A further understanding of the present invention and its objects and
 advantages will be provided by the following examples.