MXPA00007972A - Ethylene copolymerization process - Google Patents

Abstract

This invention is a solution process for the preparation of ethylene-a-olefin-diolefin copolymers comprising contacting ethylene, one or more a-olefin monomer, and one or more cyclic diene monomer, with a catalyst composition comprising a bridged, bis(cyclopentadienyl) zirconium compound having an unsubstituted cyclopentadienyl ligand, a multiply substituted cyclopentadienyl ligand, said ligands bridged by a covalent bridging group containing one or more Group 14 element, and two uninegative, activation reactive ligands and a catalyst activator compound. The invention process exhibits high catalyst activity, high comonomer incorporation and high diene monomer conversion rates and is particularly suitable for the preparation of elastomeric ethylene-propylene or ethylene-propylene-diene monomer elastomers.

Description

ETHYLENE CO-POLYMERIZATION PROCESS Technical Field This invention relates to the preparation of ethylene / α-olefin polymers under polymerization conditions of solutions using catalyst compositions based on zirconium biscyclopentadienyl derivatives. BACKGROUND OF THE INVENTION Polymers comprising ethylene and at least one or more olefins and optionally one or more diolefins comprise a large segment of polyolefin polymers and will be referred to by convenience herein as "ethylene / α-olefin-diolefin copolymers". These polymers range from crystalline polyethylene copolymers to very amorphous elastomers, with a new area of semicrystalline "plastomers" in between. In particular, ethylene / α-olefin-diolefin elastomers are a well-established class of industrial polymers having a variety of uses associated with their elastomeric properties, their thermo-oxidant stability, their solubility in oleaginous hydrocarbon fluids, and their capacity to modify the properties of polyolefin blends. Included in this terminology are the commercially available rubber polymers of ethylene-propylene monomer (EPM) and ethylene-propylene-diene monomer (EPDM), both being vulcanizable by crosslinking, the addition of diolefin, also known as diene monomer, provides increased ease for both cross-linking and functionalization. The commercially prepared ethylene / α-olefin-diolefin elastomers have traditionally been made by the polymerization of Ziegler-Natta with largely homogenous catalyst compositions based on vanadium or titanium. Newer metallocene catalyst compounds have received attention due to their ease of incorporation of larger monomers and potential increases in polymerization activities. U.S. Patent No. 5,324,800 discloses metallocenes having substituted and unsubstituted cyclopentadienyl ligands that are suitable for producing high molecular weight olefin polymers, including linear, low density copolymers of ethylene with small amounts of α-olefin. International publication WO 95/277147 describes bridged and non-bridged Group 4 metallocene compounds, wherein the cyclopentadienyl ligands have two or four adjacent substituents that form one or two alkylenic rings of 4 to 8 carbon atoms. These compounds are said to be useful for the copolymerization of ethylene and the polymerization of propylene, including elastomeric copolymers of ethylene, α-olefins and unconjugated diolefins. The copolymerization of ethylene with propylene is reported in Examples 28-30 and Table 3. U.S. Patent No. 5,543,373 describes bridged metallocenes having two different p-ligands that are said to be highly active. Copolymers of ethylene with 1-olefins and / or one or more diene monomers are produced in a preferred process according to the invention. Example R illustrates an ethylene-propylene-diene terpolymer rubber prepared with dimethylsilanediyl (2-methyl-4-phenyl-1-indenyl) (2,3,5-trimethyl-1-cyclopentadienyl) zirconium dichloride. The copolymerization of ethylene is described in international publication WO 95/27717 with zirconocenes having a Cp cyclopentadienyl group with one or two alkylenic cycles of 4 to 8 carbon atoms, and a cyclopentadienyl group Cp 'having up to 4 substituents R. Example 12 illustrates the preparation of isopropylidene (cyclopentadienyl) (2,3-cyclotetramethyleneinden-1-yl) zirconium dichloride. Example 19 illustrates the polymerization of syndiotactic propylene with this catalyst. A high temperature solution process for the preparation of ethylene / α-olefin copolymers is described in EP-A-0 612 769. The catalyst compositions are based on bis (cyclopentadienyl / indenyl / fluorenyl) itanocenes / zirconocenes, which are they combine with alkylaluminum compounds and an ionic ionizing compound that provides a noncoordinating anion. Asymmetrically substituted catalysts are illustrated. The compound is reacted with the organic aluminum compound, then it is reacted with the ionic ionizing compound, and subsequently added to the polymerization reactor. It is said that the high molecular weight polymer is produced at high efficiency. A supported catalyst of high activity suitable for ethylene copolymers is described in U.S. Patent No. 5,240,894. The isopropylidene (cyclopentadienyl) (fluorenyl) zirconium dichloride catalyst is a preferred metallocene embodiment. Example 10 illustrates a copolymerization of ethylene-propylene. It remains important in the industry to develop efficient copolymerization processes, and in particular, those capable of high polymer productivity per unit weight of catalyst compound. Description of the Invention The invention is a polymerization process for the preparation of ethylene / α-olefin-diolefin copolymers comprising contacting ethylene, one or more α-olefin monomers, and optionally, one or more cyclic diolefin monomers. , with a catalyst composition prepared from at least one catalyst activator, and at least one bridged bis (cyclopentadienyl) zirconium compound having an unsubstituted cyclopentadienyl ligand, a bulky substituted cyclopentadienyl ligand, bridged the ligands by a covalent bridging group containing one or more elements of Group 14, conducted the process in a solution polymerization process. The process of the invention exhibits high catalyst activity, high co-monomer incorporation and high diene monomer conversion rates. BEST MODE AND EXAMPLES OF THE INVENTION It is understood that the ethylene / α-olefin-diolefin copolymers of this invention (hereinafter referred to as "EPC") include copolymers, terpolymers, tetrapolymers, etc. Typically they comprise ethylene, one or more alpha-olefins, and optionally, one or more cyclic diolefin monomers; they are typically substantially amorphous; and typically have a substantially random arrangement of at least the ethylene and alpha-olefin monomers. In this way both the ethylene copolymers containing elastomers and plastomers can be prepared by the process of the invention. The ethylene / α-olefin-diolefin copolymers capable of preparation according to the process of the invention can generally have a molecular weight range typically between about 20,000 and up to about 500,000 or greater, more typically between about 60,000 and 300,000, where the Molecular weight is the numerical average ("Mp"). The ethylene / α-olefin-diolefin copolymers are "substantially amorphous", and when that term is used to define the ethylene / α-olefin-diolefin elastomers of this invention, it will be taken as meaning that they have a lower degree of crystallinity of about 25 percent, measured by means known in the art, preferably less than about 15 percent, and more preferably less than about 10 percent. The three most important methods known to determine crystallinity are based on the specific volume, its X-ray diffraction, and infrared spectroscopy. Another well-established method, based on the measurement of the heat content as a function of the temperature across the melting range, is carried out using differential scanning calorimetric measurements. It is known that these independent techniques lead to reasonably good experimental agreement. The degree of randomness of the arrangement of the monomers in the ethylene / α-olefin-diolefin elastomeric polymers also affects the crystallinity and is appropriately characterized by the degree of crystallinity. Additionally, it is known in the art that the tendency of a particular combination of catalyst composition and monomers to produce block, random, or alternating polymers can be characterized by the product of the reactivity ratios defined by the monomers given under the reaction conditions. specific found. This product is equal to 1.0, the sequence distribution will be perfectly random; the more product is less than 1.0, the more monomers will tend to have an "en bloc" sequence distribution. Generally speaking, the segments of a polymer that is crystallized are linear segments of a polymer having a number of identical units in a row (both by chemical configuration and by stereo-specific orientation). These segments are said to be "in blocks". If there is little or no sequential order within the segments that make up a polymer chain, this chain is very unlikely to conform in the correct way to fit in the spatial order of a crystal and accordingly will exhibit a low degree of crystallinity. See, "Ethylene-Propylene Copolymers, Reactivity Ratios, Evaluation and Significance," C. Cozewith and G. Ver Strate, Macromelecules, Volume 4, No. 4, 482-489 (1971). The ethylene / α-olefin-diolefin elastomers of this invention according to the above can be characterized in one embodiment by the limitation that their method of preparation has a product of reactivity ratio less than 2.0, preferably less than about 1.5, and more preferably less than about 1.25. The ethylene / α-olefin-diolefin elastomers of the invention will contain from about 10 to about 91 weight percent ethylene, preferably about 20 to 88 weight percent ethylene. The ethylene / α-olefin-diolefin elastomers of the invention preferably contain from 35 to 75 weight percent ethylene. Suitable α-olefins for use in the preparation of ethylene / α-olefin-diolefin, or for polyethylene copolymers, are preferably α-olefins with 3 to 20 carbon atoms, but will include olefins with higher numbers of carbon atoms. carbon, such as polymerizable macromers having up to five hundred carbon atoms or more. Illustrative non-limiting examples of these α-olefins are one or more of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-decene. Included in the term of α-olefins for the purposes of describing effectively copolymerized monomers are cyclic ring-ring monoolefins, such as cyclobutene, cyclopentene, norbornene, alkyl-substituted norbornenes, alkenyl-substituted norbornenes, and cyclic olefins with number of Larger carbon atoms known in the art, see U.S. Patent No. 5,635,573, incorporated herein by reference for the purpose of patent practice in the United States. The a-olefin content of the ethylene / α-olefin-diolefin polymer varies depending on the selection of the specific α-olefin or α-olefins, being more for the monomers with lower carbon number, for example, about 10 up to about 91 weight percent, preferably about 20 to about 88 weight percent for propyleneLTI ; and, from 5 to 35 mole percent, preferably 7.5 to 25 mole percent, and more preferably from 10 to 20 mole percent for 1-octene. The ethylene / α-olefin-diolefin elastomers typically have about 25 mole percent incorporation of α-olefin. For the more crystalline polyethylene copolymers, the range of co-tnonomer addition will typically be below 25 mole percent, and more typically below about 15 mole percent. In terms of polymer density, the elastomers are typically below about 0.860 grams / d3, and the ethylene plastomer copolymers are from about 0.860 to 0.915. The diene monomers, or diolefins, useful in this invention include those typically used in known ethylene-propylene-diene monomer polymers. Typically used diene monomers are generally selected from cyclic diolefins having from about 6 to about 15 carbon atoms, for example: A. single ring alicyclic dienes, such as 1,3-cyclopentadiene; 1,4-cyclohexadiene; 1,5-cyclooctadiene and 1,5-cyclododecadiene; B. bridged ring and muyclic alicyclic fused ring dienes, such as tetrahydroindene, methyltetrahydroindene, dicyclopentadiene; bicyclo- (2,2,1) -hepta-2, 5-diene; alkenyl, alkylindene, cycloalkenyl and cycloalkylidene norbornenes, such as 5-methylene-2-norbornene (MNB), 5-ethylidene-2-norbornene, 5-isopropylidene-2-norbornene, 5- (4-cyclopentenyl) -2-norbornene , 5-cyclohexylidene-2-norbornene, 5-vinyl-2-norbornene; and C. alkenes substituted by cycloalkenyl, such as allylcyclohexene, vinylcyclooctene, allylcyclohexene, vinylcyclooctene, allylcyclodecene, vinylcyclododecene. Of these, the preferred dienes are dicyclopentadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene. It will be apparent that a mixture of these dienes can also be used. The content of the diene monomer in the ethylene-α-olefin-diolefin elastomer may be from 0 to about 20 weight percent, and if used, preferably from 0.5 to about 15 weight percent, and more preferably from about 2.0 up to about 12.0 weight percent. Surprisingly, the incorporation of diene greater than 5.0 weight percent, even greater than 8.0 weight percent is made possible using the process of this invention. The bridged bis (cyclopentadienyl) compounds of this invention typically comprise those that have auxiliary ligands that include the unsubstituted cyclopentadienyl ligand, a bulky cyclopentadienyl ligand muly substituted, the cyclopentadienyl ligands covalently bridged, and two reactive activation ligands, uni-negative , at least one of which may be abstracted from the activation of the remaining metal compound to a catalytically active state and one of which may be similarly extractable or have an s-bond to the transition metal, in which an olefin or diolefin It can be inserted for coordination polymerization. Thus, the bridged bis (cyclopentadienyl) zirconium compounds of the present invention have the following structure: wherein the unsubstituted cyclopentadienyl ring is Cp1, and the cyclopentadienyl ring (Cp2Rn) has at least two non-hydrogen radical substituents R1, wherein each R1 is, independently, a radical selected from: a) hydrogen radical, b) hydrocarbyl, silyl or germyl radicals having from 1 to 20 carbon atoms, silica or germanium atoms, c) substituted hydrocarbyl, silyl or germyl radicals as is defined, where one or more hydrogen atoms are replaced by a halogen radical, an amido radical, a phosphide radical, an alkoxy radical, an aryloxy radical or any other radical containing an acid or basic Lewis functionality, metalloid substituted by hydrocarbyl with 1 to 20 carbon atoms, where the metalloid is selected from the group consisting of Ge, Sn and Pb, e) halogen radicals, f) amido radicals, g) phosphide radicals h) alkoxy radicals, and i) alkylboride radicals; or at least two R1 groups are joined together to form, together with the carbon atoms to which they are attached, a ring structure with 4 to 20 carbon atoms, which is saturated or partially saturated, and substituted or unsubstituted , the substitution of the ring structure being selected from one or more groups R1 as defined under (a) - (i) above. X is selected from the group consisting of C, Si, Ge, Sn and Pb; R2 is selected from the group consisting of H, hydrocarbyl with 1 to 20 unsubstituted carbon atoms, hydrocarbyl of 1 to 20 carbon atoms substituted with at least one of Si, and a hydrocarbyl with 1 to 20 carbon atoms substituted with at least one Ge; m = 0 or 1, Y is selected from the group consisting of hydrocarbyl radicals, hydrosilyl radicals, and hydrogermyl radicals; Y Q1 and Q2 are non-cyclopentadienyl radicals, where: i) independently, each Q is selected from the group consisting of halide, hydride, hydrocarbyl with 1 to 20 unsubstituted carbon atoms, hydrocarbyl with 1 to 20 carbon atoms substituted with at least one group R1 as defined under (a) - (i) above, alkoxide, aryloxide, amide, halide or phosphide; or ii) together, Q1 and Q2 can form an alkylidene, cyclometalized hydrocarbyl or any other bivalent anionic chelating ligand. Preferred zirconium compounds where two sets of groups R1 are joined together have the following structure: wherein the unsubstituted cyclopentadienyl ring is Cp1, and the substituted fluorenyl ring has at least two radical substituents that are not hydrogen, wherein each R1 is, independently, a radical selected from: a) hydrogen radical b) hydrocarbyl, silyl or germyl radicals having from 1 to 20 carbon atoms, silica or germanium atoms, c) substituted hydrocarbyl, silyl or germyl radicals as defined, where one or more hydrogen atoms are replaced by a halogen radical, an amido radical, a radical phosphide, an alkoxy radical, an aryloxy radical or any other radical containing an acid or basic Lewis functionality, d) hydrocarbyl substituted hydrocarbyl radicals with 1 to 20 carbon atoms, wherein the metalloid is selected from the group consisting of Ge, Sn and Pb, e) halogen radicals, f) amido radicals, g) phosphide radicals, h) alkoxy radicals, and i) alkylboride radicals; or at least two R1 groups are joined together to form, together with the carbon atoms to which they are attached, a ring structure with 4 to 20 carbon atoms, which is saturated or partially saturated, and substituted or unsubstituted , the substitution of the ring structure being selected from one or more groups R1 as defined under (a) - (i) above. X is selected from the group consisting of C, Si, Ge, Sn and Pb; R2 is selected from the group consisting of H, hydrocarbyl with 1 to 20 unsubstituted carbon atoms, hydrocarbyl of 1 to 20 carbon atoms substituted with at least one of Si, and a hydrocarbyl with 1 to 20 carbon atoms substituted with at least one Ge; m = 0 or 1, Y is selected from the group consisting of hydrocarbyl radicals, hydrosilyl radicals, and hydrogermyl radicals; Y Q1 and Q2 are non-cyclopentadienyl radicals, where: i) independently, each Q is selected from the group consisting of halide, hydride, hydrocarbyl with 1 to 20 unsubstituted carbon atoms, hydrocarbyl with 1 to 20 carbon atoms substituted with at least one group R1 as defined under (a) - (i) above, alkoxide, aryloxide, amide, halide or phosphide; or ii) together, Q1 and Q2 can form an alkylidene, cyclometalized hydrocarbyl or any other bivalent anionic chelating ligand. These compounds may also include an Lw complexed thereto, wherein L is a neutral Lewis base, such as diethyl ether, tetrahydrofuran, dimethylaniline, aniline, trimethylphosphine, n-butylamine, and the like; and "w" is a number from 0 to 3. The term "cyclopentadienyl" refers to a 5-membered ring having delocalised bonds within the ring, and is typically linked to M through 5 bonds, which typically forms carbon. most of the positions of the 5 members. Examples of the bridged bis (cyclopentadienyl) -zirconium compounds of the invention include: dimethylsilanyl (cyclopentadienyl) (trimethyl-cyclopentadienyl) zirconium dichloride, dimethylsilanyl (cyclopentadienyl) (trimethylcyclo-pentadienyl) zirconium dimethyl, dimethylsilanyl (cyclopentadienyl) (trimethylcyclopenta -dienyl) dibenzyl zirconium, diphenylsilanyl (cyclopentadienyl) (trimethyl-cyclopentadienyl) zirconium dichloride, diphenylsilyl (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium dimethyl, diphenylsilyl (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium dibenzyl, diphenylmethylene (cyclopentadienyl) (tri-methylcyclopentadienyl) zirconium dichloride, methylphenylmethylene (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium dimethyl, diphenylmethylene (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium dibenzyl, silacyclobutyl (cyclopentadienyl) (tri-methylcyclopentadienyl) zirconium dichloride, silacyclobutyl (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium dimethyl, silacyclobutyl (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium dibenzyl, isopropylidene dichloride (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium, isopropylidene (cyclopentadienyl) (trimethylcyclopentadienyl) zirconium dimethyl, isopropylidene ( cyclopentadienyl) (trimethylcyclopentadienyl) dibenzyl zirconium, dimethylsilanyl (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, dimethylsilanyl (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dimethyl, dimethylsilanyl (cyclopentadienyl) (tetramethyl) clopenta-dienyl) dibenzyl zirconium dichloride difenilsilanil (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium difenilsilanil (cyclopentadienyl) (tetramethylcyclopentadienyl) dimethyl zirconium, difenilsilanil (cyclopentadienyl) (tetramethylcyclopentadienyl) dibenzyl zirconium dichloride, diphenylmethylene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium methylphenylmethylene (cyclopentadienyl) (tetramethylcyclopentadienyl) dimethyl zirconium, diphenylmethylene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dibenzyl dichloride, silacyclobutyl (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, silacyclobutyl (cyclopentadienyl) (tetramethylcyclopentadienyl) dimethyl zirconium, silacyclobutyl (cyclopentadienyl) (tetramethylcyclopentadienyl) dibenzyl zirconium, isopropylidene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dimethyl ester, isopropylidene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dibenzyl. Substituted versions where a hydride, hydrocarbyl, germyl or silyl group replaces one or more M chloride ligands are convenient according to the invention, particularly where the anion ionizing precursors are activators. Separate or on site alkylation is typical, for example, dimethyl replacing dichloride. A preferred catalyst according to the invention will be one in which Cp2 is tri- or tetra-alkyl substituted with methyl, ethyl, isopropyl or tertiary alkyl butyl groups, or mixed combinations of two or more of these alkyl groups. Preferred bridged groups, particularly suitable for increased activity and for increased molecular weights, are both silacyclic and aryl groups containing methylene groups, for example, silacyclobutyl, methylphenylmethylene and diphenylmethylene.

The bridged bis (cyclopentadienyl) zirconium compounds according to the invention can be activated for the polymerization of olefins catalyst in any sufficient manner, both to remove or complex a group Q, so that the center of the metal becomes sufficiently deficient in electrons to attract olefinically unsaturated monomers, so that another Q bond is the same, or is extracted and replaced with another Q bond, weak enough to allow insertion thereof into an olefinically unsaturated monomer to produce a growing polymer, in the manner of Polymerization by traditional coordination / insertion. Traditional activators of the metallocene polymerization technique are convenient, which typically include Lewis acids, such as aluminum alkyls or alumoxane compounds, and anion ionization precursors that attract a Q, so as to ionize the metal center in a cation and provide a non-coordinating anion of counterbalance. The term "non-coordinating anion" means an anion that does not coordinate with said transition metal cation, or which only weakly coordinates with the cation, whereby it remains sufficiently labile to be displaced by a neutral Lewis base. The "compatible" noncoordinating anions are those that are not degraded to neutrality when the initially formed complex decomposes. In addition, the anion will not transfer an anionic substituent or fragment to the cation to cause it to form a neutral four-coordinate metallocene compound, and a neutral by-product from the anion. The non-coordinating anions useful in accordance with this invention, are those that are compatible, stabilize the metallocene cation in the sense of balancing its ionic charge in a state at +1, retaining sufficient lability to allow the displacement of an ethylenically or acetylenically unsaturated monomer during the polymerization. Additionally, the anions useful in this invention will be large or bulky in the sense of molecular size sufficient to greatly inhibit or prevent the neutralization of the metallocene cation by Lewis bases other than the polymerizable monomers that may be present in the polymerization process. Typically the anion will have a molecular size greater than or equal to about 4 Angstroms. Descriptions of ionic catalysts for coordination polymerization composed of metallocene cations activated by anion ionizing precursors appear in the above work in EP-A-0 277 003, EP-A-0 277 004, United States Patent No. 5,198,401 and 5,278,119, international publication WO 92/00333. These show a preferred method of preparation, where the metallocene compounds are protonated by anionic precursors, so that the alkylamide group is abstracted from the transition metal to make it both cationic and balanced in charge by the non-coordinating anion . The use of ionic ionization compounds that do not contain an active proton, but capable of producing both the active metallocene cation and the non-coordinating anion are also known. See, EP-A-0 426 637, EP-A-0 573 403 and U.S. Patent No. 5,387,568. Reactive cations other than Bronsted acids, capable of ionizing the metallocene compounds include ferrocenium, triphenylcarbonium and triethylsilyilinium cations. Any metal or metalloid capable of forming a coordination complex that is resistant to degradation by water (or other Bronsted or Lewis Acid) can be used or contained in the anion of a second activating compound. Suitable metals include, but are not limited to, aluminum, gold, platinum and the like. Suitable metalloids include, but are not limited to, boron, phosphorus, silica and the like. The description of non-coordinating anions and precursors thereto of these documents are incorporated by reference for purposes of United States patent practice. An additional method to make the ionic catalysts uses anion ionizing precursors which are initially neutral Lewis acids, but form the cation and the anion after the ionization reaction with the metallocene compounds, for example, tris (pentafluorophenyl) boron acts to abstract an alkyl, hydride or silyl ligand to produce a metallocene cation and a non-coordinating stabilizing anion , see EP-A-0 427 697 and EP-A-0 520 732. Ionic catalysts for addition polymerization can also be prepared by the oxidation of metal centers of transition metal compounds by anionic precursors containing oxidizing groups metals, together with the anion groups, see EP-A-0495375. The description of non-coordinating anions and precursors thereof from these documents are similarly incorporated by reference for purposes of United States patent practice. Examples of suitable anion precursors capable of ionic cationization of the metallocene compounds of the invention, and the consequent stabilization with a resulting non-coordinating anion include trialkyl-substituted ammonium salts, which are well known in the art, see US Pat. United States No. 5,198,401 and the international publication WO-A-96/33227, and others above. Other examples of suitable anion precursors include those comprising a stable carbonium ion, and a compatible non-coordinating anion. These include: tetrakispentafluorophenyl borate of tropilium, tetrakispentafluorophenyl borate of triphenylmethylium, tetrakispentafluorophenyl benzoate (diazonium), phenyltris-pentafluorophenyl borate of tropilium, phenyl-trispentafluorophenyl borate of triphenylmethyl, phenyltrispentafluorophenyl benzoate (diazonium), tetrakis (2, 3, 5 , 6-tetrafluorophenyl) borate of tropilium, tetrakis (2, 3, 5, 6-tetrafluorophenyl) borate of triphenylmethylium, tetrakis (3,4,5-trifluorophenyl) borate of benzene (diazonium), tetrakis (3, 4, 5- trifluorophenyl) borate of tropylium, tetrakis (3,4,5-trifluorophenyl) borate of benzene (diazonium), tetrakis (3,4,5-trifluorophenyl) aluminate of tropylium, tetrakis (3,4,5-trifluorophenyl) aluminate of triphenylmethylium) , tetrakis (3, 4, 5-trifluorophenyl) - benzene aluminate (diazonium), tetrakis (1,2,2-trifluoroethenyl) borate of tropilium, tetrakis (1,2,2-trifluoroethenyl) borate of triphenylmethylium, tetrakis (1, 2, 3-trif luoroethenyl) -benzene (diazonium) borate, tetrakis (2, 3, 4, 5-tetrafluorophenyl) borate of tropylium, tetrakis (2, 3,4, 5-tetrafluorophenyl) borate of triphenylmethylium, tetrakis (2, 3, 4, 5-tetrafluorophenyl) benzene (diazonium) borate, and diethylammonium n-butyltris (pentafluorophenyl) borate. Where the metal ligands include Q-halide fractions, such as in (cyclopentadienyl) -dimethylsilyl (tetramethylcyclopentadienyl) zirconium dichloride, which are not capable of discrete ionization abstraction under normal conditions, these fractions can be converted via known alkylation reactions with organic metal compounds, such as lithium or aluminum hydrides or alkyls, alkylalumoxanes, Grignard reagents, etc. See EP-A-0 500 994, EP-A1-0 570 982 and EP-A1-0 612 769 for processes that describe the reaction of alkylaluminum compounds with metallocene compounds substituted by dihalide before or with the addition of precursor compounds of activation anions. The known alkylalumoxanes are furthermore suitable as catalyst activators, particularly for the metal compounds of the invention which comprise the halide ligands. The alumoxane component useful as a catalyst activator is typically an oligomeric aluminum compound represented by the general formula (R-Al-O) n, which is a cyclic compound, or R (R-Al-O) nAlR2, which is a linear compound. In the general alumoxane formula R is an alkyl radical having from 1 to 5 carbon atoms, for example, methyl, ethyl, propyl, butyl or pentyl, and "n" is an integer from 1 to about 50. More preferably, R is methyl and "n" is at least 4. The alumoxanes can be prepared by various methods known in the art. For example, an alkylluminium can be treated with water dissolved in an inert organic solvent, or it can be contacted with a hydrated salt, such as hydrated copper sulfate suspended in inert organic solvent, to produce an alumoxane. Generally, however prepared, the reaction of an alkylaluminum with a limited amount of water produces a mixture of linear and cyclic species of alumoxane. When using ionic catalyst comprising bridged Group 4 metal cations and non-coordinating anions, the total catalyst composition generally additionally comprises one or more dissociating compounds. The term "dissociating compounds" as used in this application and its claims means that it includes those compounds effective to remove polar impurities from the reaction solvent. These impurities can be inadvertently introduced with any of the components of the polymerization reaction, particularly with the solvent, the monomer and the catalyst feed, and adversely affect the activity and stability of the catalyst. It may result in a decrease or even elimination of the catalytic activity, particularly when a pair of non-coordinating anion metallocene cation is the catalyst composition. Polar impurities, or catalyst poisons include water, oxygen, metal impurities, etc. Steps are preferably taken prior to the provision of these in the reaction vessel, for example, by chemical treatment or careful separation techniques after or during the synthesis or preparation of the various components, but some minor amounts of the dissociating compound will be required. normally in the same polymerization process. Typically the dissociating compounds will be an organic metal compound, such as organic metal compounds of Group 13 of US Pat. Nos. 5,153,157; 5,241,025, EP-A-0 426638 and WO-A-91/09882 and WO-A-94/03506, mentioned above, and those of WO-A-93/14132 and WO-A-97/22635. Exemplary compounds include triethylaluminum, triethylborane, tri-isobutylaluminum, methylalumoxane, isobutylaluminum-oxano, and tri-n-octylaluminum, those having bulky substituents or 6 carbon atoms or larger linear substituents covalently bonded to the metal or metalloid center, being preferred to minimize the adverse interaction with the active catalyst. When an alkylaluminum or alumoxane is used as an activator, any excess on the amount of metallocene present will act as dissociating compounds and additional dissociation compounds may not be necessary. The amount of dissociating substance to be used with the non-coordinating metallocene-anion cation pairs is minimized during the polymerization reactions to the effective amount to increase the activity. In the process described in this invention, it was found that there is an optimal contact time between the dissociating compound and the reaction mixture to maximize the catalyst activity. If the contact time is too long, a deactivation of the harmful catalyst could occur. All documents are incorporated by reference. The solution process for the production of ethylene / α-olefin-diolefin elastomers according to this invention improves the economy of the process and increases the capacities of the product. Due to process economy, the combination of high catalyst activity and solvent recovery systems provides significant cost improvements. The improved economy of the high catalytic activity solution process compared to the conventional process is related to savings in the finishing area, as it does not require catalyst cleaning facilities. In addition, efficient solvent recycling also reduces the environmental impact of the process with respect to volatile organic compound emissions to meet the strictest regulatory levels each time. Additionally, the use of the process of the invention allows high conversions of diolefins from monomer to incorporate raer unit in the polymer, thereby reducing separation and recycling costs. The typical conversion ratios of the diolefin monomer can vary from 20 percent, 30 percent or up to as much as 40 percent, and higher. The polymerization process of the invention involves contacting the polymerizable monomers (ethylene, α-olefin and, diene monomer) in solution with the described ionic catalyst composition, preferably at high reaction temperatures, from about 20 ° C to about 180 ° C, and it can be conveniently carried out in the following manner. The solvent is heated to the reaction temperature before introduction into the reaction vessel. The solvent is provided to the reaction vessel after the polymerizable monomer is introduced, either in liquid, gas or solution form in that reaction solvent. A reaction medium comprising the solvent is formed, within which the catalyst composition and the monomers are contacted for the polymerization reaction. Typically, the dissociating compound is introduced into the reaction solvent to reduce or eliminate the catalyst poisons present in any of the components of the reaction medium prior to introduction into the reactor. If the dissociating compound and the activator are different, and contact each other for a sufficient length of time, adverse effects on the effectiveness of that activator may occur. In this process, the activator and the metallocene compound are contacted in the polymerization reaction vessel in the presence of the polymerizable monomers, which comprise activation at the site. A convenient solution reaction can be carried out at pressures from atmospheric to 1 to 35 bar, preferably from 8 to 21 bars. Preferred reaction temperatures are above 30 ° C, preferably up to and above about 80 ° C. Typically the polymerization reaction will be exothermic and the reactor or reactor feeds will be frozen or cooled according to known methods to ensure that the temperatures do not exceed those reasonably convenient for the polymer to be produced. Another preferred process in which any catalyst, cocatalyst and cleavage selections described in this application can be advantageously practiced is that of a continuous process, in solution, operated above 90 ° C to 200 ° C, preferably above 110 ° C. Typically, this process is carried out in inert, linear, cyclic or branched aliphatic hydrocarbon solvent, or aromatic, at a pressure of 20 to 200 bar, the reactants being added directly in a convenient reaction vessel containing the solvent at temperatures of preferred operations. A homogeneous additionally suitable process for the polymerization is conducted at a high pressure, that is from 200 to 3,000 bars, preferably from 500 to 2,500 bars in a single homogeneous phase or two fluid phases, with or without unreacted diluents or solvents at temperatures generally above the melting point of the polymer that is being produced. These processes are typically known and may include the use of dissociating compounds and catalyst deactivation or removal steps, see for example U.S. Patent No. 5,408,017, WO 95/07941, WO 92/14766 and WO 97/22635. Each of these documents and their counterparts in the United States are incorporated by reference for purposes of United States patent practice. Preferred catalyst deactivators, or scavengers, include high molecular weight non-recyclable compounds, such as polyvinyl alcohol, which has the functional ability to complex with the catalyst, so as to deactivate them although they do not form volatile polar by-products or unreacted residual compounds. . The purification of feed material prior to introduction into reaction solvent follows normal practices in the art, for example, molecular sieves, aluminum oxide beds and oxygen scavenging catalysts are used for the purification of ethylene, α-olefin and optional diene The same solvent also, for example, hexane and toluene, are treated in a similar manner. The purification of the dienes was observed to increase the diene conversion, better results were obtained when the diene was fractionally distilled with CaH2 as the purification method. The α-olefin monomer (s) and the diene monomer (s) introduce an amount proportional to the desired levels of incorporation for the polymer to be produced and the effective reagent ratios for the polymerizable monomers in the presence of the specific catalyst chosen. In the preferred embodiment, the combination of o-olefin monomer or monomers in the reaction solvent as it is introduced into the reactor and the effective vapor pressure of the α-olefin monomer (s) is maintained in accordance with the speed of incorporation into the copolymer product. In an alternative embodiment, the partial pressure in the reactor will be provided with ethylene only, in which the situation of the α-olefin monomer (s) is only added with reaction solvent. The amounts and the vapor pressure will vary according to the selection of catalyst and the polymer to be produced, but empirically can be determined well within the skill in the art, particularly in view of the description provided by the following examples. The catalyst activator, for example, non-coordinating anion precursor, ionizing anionic precursor, or alumoxane, may be introduced together with or separately from the introduction of the optional diolefin monomer (s)., if they are used. The diolefin can be provided in an amount effective for its reaction rate and conversion rate. The catalyst activator can be provided in an amount that is equal to 0.2 to 10 molar equivalents of the metallocene compound of Group 4, preferably 0.25 to 5, and even more preferably 0.33 to 3.0, when a non-coordinating anion precursor. Typically the provision of non-coordinating anion precursor activator will be in an effective solvent, typically an aromatic solvent, such as toluene. The monitoring of the polymerization activity by known methods will allow the online adjustment of the alumoxane to ensure that there is no excess or deficit amounts maintained during unwanted periods. Dissociating compounds are provided separately after or with one of the above feed streams, in a convenient amount to increase the activity of the catalyst, but in a lesser amount than at which reactivity depression is observed. Typically an effective amount of the dissociation compound is from about 0 (for example, with an alumoxane activator) to 100 molar ratio, based on the ratio of the dissociating compound to the activator, preferably the ratio of 0.3 to 30, and more preferably 0.5. a 10. Ethylene gas is provided in the reaction vessel in an amount proportional to the desired level of incorporation, and the reaction rates effective for the polymerizable monomers in the presence of the specific catalysts chosen, such as with the monomer (s) of -olefin. The polymerization begins after contact of the monomers with the activated catalyst and the delivery rates of each of the components of the composition are adjusted for stable operations at the level of production, molecular weight, monomer incorporation and equipment limitations. The temperature of the reaction can be allowed to exceed the initial temperature, but will preferably be all the time greater than the lower limit of the ranges described above for the process of the invention.

The solvents for the polymerization reaction will comprise those known for solution polymerization, typically the aliphatic solvents represented by hexane, or the aromatic solvents, represented by toluene. Additional examples include heptane, cyclohexane, and Isopar E (aliphatic solvent with 8 to 12 carbon atoms, Exxon Chemical Co., United States). Preferably the solvent is aliphatic, more preferably it is hexane. Although not strictly necessary for the solution polymerization process as described, the catalyst according to the invention can be supported for use in alternative gas, volume or slurry polymerization processes, where the benefits of the high activity of the catalyst is sought to be applied. Numerous methods of support are known in the art for the copolymerization processes for olefins, particularly for catalysts activated by alumoxanes, whichever is convenient for the process of the invention in its broadest scope. See, for example, U.S. Patent No. 5,227,440. An example of supported ionic catalysts appears in the international publication WO 94/03056. When a Lewis acid ionizing catalyst activator is used, a particularly effective method is that described in U.S. Patent No. 5,643,847. A bulk or slurry process using metallocenes from Group 4 biscyclopentadienyl with alumoxane co-catalysts is described as being convenient for ethylene-propylene monomer and ethylene-propylene-diene monomer in U.S. Patent Nos. 5,001,205 and 5,229,478, these processes will additionally be convenient with the catalyst compositions of this application. Each of the above documents is incorporated by reference for purposes of United States patent practice. Although the examples and discussion are directed to a single reactor configuration and narrow polydispersity polymers, it is well known that the serial use of two of these reactors, each operated to achieve different polymer molecular weight characteristics, or by mixing polymers of different reactor conditions or using two or more different transition metal catalysts in one or more reactors, can produce improved processing polymers. The disclosures of U.S. Patent No. 4,722,971 and the international publication WO 93/21270 are instructive, and are incorporated for purposes of United States patent practice. Although it is directed to the use of vanadium catalysts, the substitution of the catalyst compositions of this invention in such a reactor, or two different catalysts of the invention in two of these reactors, or the similar use in two separate polymerizations with subsequent physical mixing of the polymer products, will allow to adapt to the measure of the characteristics (for example, molecular weights and contents of diene) suitable to balance the properties of vulcanization with the processability. Similarly, the use of mixed catalyst compositions, the catalyst of the invention with them or with others, in one or more of these reactors will allow the preparation of bimodal or multimodal ethylene / α-olefin-diolefin polymers having properties of improved processing. The following examples are presented to illustrate the previous discussion. All parts, proportions and percentages are by weight, unless otherwise indicated. Although the examples may be directed to certain embodiments of the present invention, they are not seen as limiting the invention in any specific aspect. Methods for determining Mn and monomer content by nuclear magnetic resonance and GPC for the illustrative examples of ethylene-propylene-diene monomer of the invention are described in U.S. Patent No. 5,229, 478, which is incorporated by reference for purposes of United States patent practice. For the measurement of the co-monomer content in the ethylene / α-olefin-diolefin elastomers, the method of ASTM D3900 was used for ethylene-propylene copolymers between 35 and 85 weight percent ethylene. Outside that range, the nuclear magnetic resonance method was used. See also, U.S. Patent No. 4,786,697, which is incorporated by reference for purposes of United States patent practice.

Ex emplos Example 1; Synthesis of EPDM The polymerizations were carried out in a 500 c autoclave reactor operated at a temperature of 115 ° C in the batch mode for the polymer and a semilote for the ethylene monomer. The following procedure was used for the polymerizations: • The reactor was charged with 250 ce of purified hexane, 5 ce of 10 percent by weight toluene solution of MAO (activator) and 3 ce of purified ENB (fractional distillation with CaH2) . • The reactor was heated to 115 ° C, resulting in a hexane vapor pressure of about 2.5 bar. • Propylene was added to the reactor to reach 7.48 bar of pressure (liquid phase molar concentration = 0.856M). • Ethylene was added to the reactor to reach a pressure of 16 bar (liquid phase concentration = 0.871M). These conditions determined the initial molar ratio of ethylene / propylene equal to 1.018. The molar ratio of ethylene / ENB was 10.43. • The catalyst solution was pumped into the reactor to maintain the constant polymerization rate as indicated by the cost of ethylene replacement to the reactor. The pump was adjusted to maintain this speed at approximately 0.1 SLPM (L / min, standard, standard conditions 1 bar, 21.1 ° C), to achieve approximately 10 grams of polymer yield.

• Irganox 1076 was added to the hexane solution at the final concentration of 0.1 mg / cc to avoid degradation of the sample. The polymers were made from the solution by precipitation with IPA. After filtering and removing free solvents, the polymer samples were dried under vacuum at 90 ° C for about 1 hour. The analysis of the polymers was done by nuclear magnetic resonance of XH to determine the content of ENB and GPC for the molecular weight of ethylene-propylene-diene monomer. Table 1: Result for Example 1 Catalyst: dimethylsilanyl (tetramethylcyclopentadienyl) (cyclopentadienyl) zirconium dichloride. Activator: methylalumoxane Temperature: 115 ° C Pressure: 235 psig The efficiency of the catalyst for these two examples was 162.8 and 670 kilogram of polymer / gram of transition metal, respectively.

Example 2: Synthesis of EPDM The same procedure as described in Example 1 was carried out with the non-coordinating anion activator and with the following differences. • At room temperature, after the reactor was charged with 200 cc of hexane, 50 cc of the 1.5 x 10"3 M activator solution in toluene was added in. The reactor was heated to 115 ° C, as in Example 1 • To the reactor pressurized after the addition of ethylene, 10 microliters of 2M TIBAL in pentane was added as the dissociator at least one minute before starting the pumping of the catalyst Table 2: Results for Example 2 Catalyst: isopropylidene dimethyl ( cyclopentadienyl) fluorenyl) zirconium Activator: dimethylanilinium tetra (pentafluoro-phenyl) borate, temperature: 115 ° C Pressure: 235 psig The efficiency of the catalyst in this example was 146 kilograms of polymer / gram of transition metal.

Example 3 (Comparative): Synthesis of EPDM The same procedure as described in Example 2 was carried out with the following catalyst: Table 3: Results of Comparative Example 2 Catalyst: (see the catalyst code in the following table). Activator: (see the catalyst code in the following table). Temperature: 115 ° C Pressure: 235 psig * Product of kilogram of polymer per gram of transition metal in the catalyst. C-1: dimethylsilanyl dichloride (tetramethylcyclopenthenethyl) (cydododecylamido) titanium / methylalumoxane C-2: dimethylsilanyl (tetramethylcyclopentadiene) (admantylamido) dimethyl titanium / dimethylanilinium tetrakis (pentafluorophenyl) borate. C-3: dimethylanilinium (pentamethylcyclopentadienyl) (cyclopen-tadienyl) zirconium dimethyl / tetrakis (penta-fluorophenyl) borate. C-4: dimethylsilanyl dichloride (2, 4-dimethylcyclo-pentadie-nyl) (fluorenyl) zirconium / methylalumoxane. C-5: dimethylsilanyl dichloride (3-n-propylcyclopenta-diethyl) (fluorenyl) titanium / methylalumoxane. C-6: Dimethylsilanyl (bis) (indenyl) zirconium dimethyl / tetrakis (pentafluorophenyl) borate dimethylanilinium. Comparative Example 3 illustrates that only the polymerization with the C-3 catalyst exhibited the high activity observed for the catalysts according to the invention. However, the polymer prepared with catalyst C-3 exhibited lower incorporation of co-monomers (both propylene and diene monomer) and, therefore, is not convenient in the process according to the invention.

Claims (8)

1. CLAIMS 1. A process for the preparation of elastomer and ethylene plastomer copolymers, comprising contacting, under conditions of solution polymerization, at a temperature of 80 to 200 * C, ethylene, one or more α-olefin monomers , and optionally one or more diene monomers, with a catalyst composition prepared from a) at least one bis (cyclopentadienyl) zirconium compound, bridged, having an unsubstituted cyclopentadienyl ligand, a tri-alkyl or tetra-alkyl cyclopentadienyl ligand substituted, said ligands bridged by a covalent bridging group containing a silicon atom, and b) at least one catalyst activator.
2. 2. The process according to claim 1, wherein the substituted cyclopentadienyl ring is tri-alkyl or tetra-alkyl substituted with methyl, ethyl, isopropyl or t-butyl alkyl groups.
3. 3. The process according to claim 2, wherein the substituted cyclopentadienyl ring is tetramethylcyclopentadiene and a) is silacyclobutyl.
4. 4. The process according to claim 1, wherein the substituted cyclopentadienyl ring is tetramethylcyclopentadiene and a) is isopropylidene or diphenylmethylene.
5. 5. The process according to claim 1, wherein said catalyst activator is an alumoxane compound.
6. 6. The process according to claim 1, wherein said catalyst activator is an ionizing precursor compound. The process of claim 1, wherein said one or more α-olefin monomers is a C3_8 α-olefin, and said one or more diolefin monomers comprises 5-ethylidene-2-norbornene or 5-vinyl-2-norbornene . The process of claim 7, wherein said one or more α-olefin monomers is propylene and said one or more diene monomers is 5-ethylidene-2-norbornene or 5-vinyl-2-norbornene.