Technical Field

This invention relates to the preparation of high molecular weight ethylene-containing copolymers under high temperature solution coordination polymerization conditions using catalyst systems based on monocyclopentadienyl derivatives of Group 4 metals

Background of the Invention

Polymers comprising ethylene and at least one or more α-olefin and optionally one or more diolefin make up a large segment of polyolefin polymers and will be addressed for convenience as "ethylene-α-olefin-diolefin copolymers" herein Such polymers lange fiom crystalline polyethylene copolymers to largely amorphous elastomers, with a new area of semi- crystalline "plastomers" in between In particular, ethylene-α-olefin-diolefin elastomers are a well established class of industrial polymers having a variety of uses associated w th their elastomeric properties, their thermo- oxidative stability, their solubility in hydrocarbon oleaginous fluids, and their capability for modifying the properties of polyolefin blends Included in this terminology are the commercially available EPM (ethylene-propylene monomer) and EPDM (ethylene-propylene-diene monomei) mbbery polymers, both being vulcanizable by cross-linking, the addition of the diolefin, also known as diene monomer, providing incieased ease of both cross-linking and function alization

Commercially prepared ethylene-α-olefin-diolefin elastomers have been traditionally been made via Ziegler-Natta polymerization with homogenous catalyst systems largely based on vanadium or titanium Newer metallocene catalyst compounds have received attention due to their ease of larger monomer incorporation and potential increases m polymeπzation activities Although broadly described as suitable for polyolefin solution polymerization processes, metallocene catalysts have shown limitations in their molecular weight capabilities Due to relatively fast termination (or chain transfer) reactions, such as the β-hydnde elimination reaction, metallocene catalysts

tend to produce polymers and copolymers of low molecular weights at high temperatures (M _n not more than about 50,000) This problem becomes more pronounced when the α-olefin comonomer content is relatively high (above 10 mol.%), which further depresses the molecular weight In addition, the incorporation of diolefins at high conversions are important, for example in the efficient production of effectively curable EPDM rubbers

Japanese unexammed patent application publication 94-80683 describes unbndged monocyclopentadienyl Group 4-6 metal compounds said to provide benefits for polypropylene polymerization and exemplifies the production of atactic polypropylene with (cyclop entadienyl) (føstnmethylsilylamide) titanium dichloπde activated with methylalumoxane at 40 °C The catalyst is said to be an active catalyst for polyolefin polymeπzation at temperatures of from - 100 °C to 200 °C, desirably at -50 °C to 100 °C Synthesis of this catalyst is described here and in "Dialkylamido denvative of [(η5-C ₅ Me5)TιCl3], [{(η ⁵ -C ₅ Me5TιCl ₂ }2(μ-O) and [{(η ⁵ - C ₅ Me5TιCl}3(μ-O)] X-ray crystal structure of [(η ⁵ -C ₅ Me5)Tι(NMe2)3", Mart'n et al. Journal of Organometalhc Chemist? y, 467 (1994), 79-84

Catalyst systems based on monocyclopentadienyl titanium compounds activated with alumoxane suitable for the preparation of ethylene-α-olefin copolymers of high molecular weight and high α-olefin content are descnbed in U S patent 5,264,405 This patent teaches that the cyclopentadienvl group should be fully substituted with methvl groups and bridged to an amido group having an aliphatic or ahcychc hydiocarbyl ligand bonded through a 1° or 2° carbon Copolymerization of ethylene with propylene in Example 45 with a bndged monocyclopentadienyl Group 4 metal catalyst compound at 80 °C produced a copolymer with 20 wt % ethylene having an M _n of about 20,080 In each Example 55 with the same catalyst as with Example 45, at a reaction temperature of 140 °C, an ethylene propylene copolymer having a density of 0 863, indicative of an amorphous ethylene copolymer, exhibited an M _7l of about 46,500

U S patent 5,321, 106 describes a broad class of Group 4 or Lanthanide series metal compounds useful as addition polymerization catalysts for ethylemcally unsaturated monomers where activated by a cationic oxidizer, the compounds comprising an anionic or non-anionic ligand system ("L"), one

of several being -NR2 where R is a hydrocarbyl, silyl, germyl, or a substituted hydrocarbyl, silyl, germyl group of from 1 to 24 carbon, silicon, or germanium atoms The preferred catalysts are monocyclopentadienyl compounds having a divalent substituted cyclopentadienyl group linked through a Y heteroatom ligand, inclusive of nitrogen hetroatoms, to the Group 4 or Lanthamde seπes metal Polymerization example 2 illustrates a preferred catalyst used for copolymenzation of ethylene and 1-octene at a temperature of 150 °C

The most commercially interesting molecular weight for elastomeric ethylene-α-olefin- diolefin copolymers exceeds about 50,000 M _n Further, the incorporation of high levels of diolefins, beyond those commercially provided by traditional Ziegler catalysts, is highly desired for improved capabilities for cross-linking in vulcanizates and m graft functionalization with non- hydrocarbyl moieties for improved compatibilityis and applications requmng greater affinity to non-hydrocarbyl chemical compounds Additionally, the use of high temperature solution processes provide the potential for industnal benefits in ease of handling the amorphous elastomers since their solubility in the polymerization solvent increases and solution viscosity is accordingly decreased A traditional bottleneck m the manufacture of elastomeric polymers at high temperatures is their resulting low molecular weight Thus an ability to capitalize on inherent solution viscosity improvements at operating temperatures higher than about 80 °C while retaining high molecular weight polymers with high comonomei content is important

Invention Disclosure

The invention is a solution process for the preparation of high molecular weight ethylene-α-olefin-diolefin copolymers compπsing contacting ethylene, one or more α-olefin monomer, and optionally one or more diene monomer, with a catalyst system prepared from at least one a catalyst activator and at least one unbndged Group 4 metal compound having a bulky monocyclopentadienyl ligand, a uninegative bulky amido ligand and two uninegative, activation reactive ligands at a polymerization temperature between about 80 °C and 160 °C By use of the invention process copolymer having high number average molecular weight (M _7l ), high α-olefin incorporation and high diolefin conversion to incorporated monomer can be

prepared under economically advantageous reaction temperatures In particular, ethylene-α-olefin-diolefin elastomers and plastomers of molecular weights greater than 55,000 M _H can be prepared under the high temperature reaction conditions

Best Mode and Examples of the Invention

The ethylene-α-olefin -diolefin copolymer elastomer or pla tomer, of this invention (hereinafter referred to as "EPC") is meant to include copolymers, terpolymers, tetrapolymers, etc It typically compnses ethylene, one or more alpha-olefins, and optionally, one or more diene monomers; it is typically substantially amorphous, and it will typically have a substantially random arrangement of at least the ethylene and the alpha-olefin monomers Though focused on EPC, the process will have utility for polyethylene copolymers (having ethylene and one or more α-olefin comonomer such as descnbed herein) having lower incorpoiation of the comonomers such that it is not elastomeric or plastomeπc as defined below but useful otherwise in the manner known in the art for such crystalline and semi-crystalline polymers Typically the polyethylene copolymers will have a polymer density of 0.86 to 0.93, while the elastomers generally will include those copolymers with even lower densities

The EPC capable of preparation in accordance with the invention process generally can have a moleculai weight lange typically between about 55,000 and up to about 500,000 oi highei , more typically between about 60,000 and 300,000 where the molecular weight is number-average ("M _n ")

Typically elastomeric EPC is "substantially amorphous", and when that term is used to define the EPC elastomers of this invention it is to be taken to mean having a degree of crystallinity less than about 25% as measured by means known in the art, preferably less than about 15%, and more preferably less than about 10% The three major known methods of determining crystallinity are based on specific volume, x-ray diffraction, and infrared spectroscopy Another well-established method, based on measurement of heat content as a function of temperature through the fusion range, is carried out using differential scanning calorimetnc measurements. It is known that these independent techniques lead to reasonably good

expeπmental agreement The degree of randomness of the arrangement of monomers in the EPC elastomenc polymers also affects the crystallinity and is appropπately charactenzed by the degree of crystallinity

Additionally, it is known m the art that the tendency of a particular combination of catalyst system and monomers to produce blocky, random, or alternating polymers can be charactenzed by the product of the reactivity ratios defined for the given monomers under the specific reaction conditions encountered If this product is equal to 1 0, the sequence distnbution will be perfectly random, the more the product is less than 1 0, the more the monomers will tend to have a "blocky" sequence distribution Generally speaking, the segments of a polymer which crystallize are linear segments of a polymer which have a number of identical (both by chemical make-up and stereo-specific onentation) units in a row Such segments are said to be "blocky" If there is httle or no such sequential order within the segments making up a polymer chain, that chain will be very unlikely to conform itself into the correct shape to fit into the spatial order of a crystal and will accordingly exhibit a low degree of crystallinity See, "Ethylene-Propylene Copolymers Reactivity Ratios, Evaluation and Significance", C Cozewith and G Ver Strate, Macromolecules, Vol 4, No 4, 482-489 (1971) The EPC elastomers of this invention accordingly can be charactenzed m one embodiment by the limitation that its method for preparation has a reactivity ratio product less than 2.0, preferably less than about 1 5, and more preferably less than about 1 25

The EPC of the invention will contain about 10 to about 90 weight percent ethylene, preferably about 20 to 85 weight percent ethylene The EPC elastomers of the invention preferably contain from 35 to 75 weight percent ethylene

The α-olefins suitable for use in the preparation of the EPC, or for the polyethylene copolymers, are preferably C , to C ₍₎ α-olefins, but will include higher carbon number olefins such as polymeπzable macromers having up to one hundred carbon atoms, or more Illustrative non- mitmg examples of such α-olefins are one or more of propylene, 1-butene, 1-pentene, 1-hexene, 1- octene, and 1-decene Included in the term α-olefins for the purposes of descnbmg effectively copolymenzed monomers are the constramed-nng cychc

olefins such as cyclobutene, cyclopentene, noibornene, alkyl-substituted norbornenes, alkenyl-substituted norbornenes, and the higher carbon number cyclic olefins known in the art The α-olefin content of the EPC ranges depending upon selection of the specific α-olefin or α-olefins, being more for lower carbon number monomers, for example, about 10 to about 90 wt.%, preferably about 30 to about 80 wt % for propylene; and, 5 to 35 mol.%, preferably 7 5 to 25 mol.% and most preferably 10 to 20 mol.% for 1-octene. The EPC plastomers typically have comonomer incorporation of from about 10 mol.% to about 25 mol.% , and the EPC elastomers typically have above about 25 mol.% α-olefin incorporation For the more crystalline polyethylene copolymers the range of comonomer incorporation will typically be below 10 mol.% and more typically below about 8 mol %

The diene monomers, or diolefins, useful m this invention include those typically used in known EPDM polymers The typically used diene monomers are generally selected from the easily polymenzable non- conjugated dienes and can be straight chain, hydrocarbon diolefins or cycloalkenyl-substituted alkenes, having about 6 to about 15 carbon atoms, for example"

A straight chain acyclic dienes such as 1,4-hexadιene and 1,6 octadiene

B branched chain acyclic dienes such as 5-methyl- l,4- hexadiene, 3,7-dιmethyl- l,6-octadιene; 3,7-dιmethyl- l,7- octadiene and the mixed isomers of dihydro-myπcene and dihydro-ocinene,

C. single ring ahcychc dienes such as 1,3-cyclopentadιene, 1,4-cyclohexadιene; 1,5-cyclo-octadιene and 1,5- cyclododecadiene,

D. multi-ring ahcychc fused and bridged ring dienes such as tetrahydromdene, methyl tetrahydroindene, dicyclopentadiene, bιcyclo-(2,2, l)-hepta-2,5-dιene, alkenyl, alklindene, cycloalkenyl and cycloalkyhdene norbornenes such as 5-methylene-2-norbornene (MNB), 5-ethyhdene-2-

norbornene, 5-ιsopropyhdene-2-norbornene, 5-(4- cyclopen enyl)-2-norbornene, 5-cyclohexyhdene-2- norbornene, 5-vιnyl-2-norbornene, and

E. cycloalkenyl-substituted alkenes, such as allyl cyclohexene, vinyl cyclooctene, allyl cyclohexene, vinyl cyclooctene, allyl cyclodecene, vinyl cyclododecene.

Of these, the preferred dienes are dicyclopentadiene, 1,4-hexadιene, 5- methylene-2-norbornene, 5-ethyhdene-2-norbornene and 5-vιnyl-2- norbornene Particularly preferred dienes are 5-ethyhdene-2 -norbornene and

1,4-hexadιene It will be apparent that a mix of such dienes can also be utilized. The content of the optional diene monomer in the EPC elastomer can be 0 to about 20 weight percent, and if used, preferably 0.5 to about 15 weight percent, and most preferably about 2.0 to about 12 0 weight percent.

Surpnsingly, diene incorporation greater than 5 0 wt.%, even greater than either 8 0 wt % or 10.0 wt % is made possible using the process of this invention The content of the optional diene monomer in the plastomer or ethylene copolymer of the invention can range similarly as that for the EPC elastomer, but will be preferably in the lower ranges, for example 0 1 to 8 mol.%

The unbndged Group 4 metal compounds of this invention typically compnse Group 4 transition metals having ancillary ligands including a substituted, bulky cyclopentadienyl ligand, a substituted, bulky Group 15 heteroatom ligand, the cyclopentadienyl ligand and heteroatom ligands not covalently bound, and two uninegative, activation reactive ligands at least one of which that can be abstracted for activation of the remaining metal compound to a catalytically active state and one of which is either similarly abstractable or has a sigma bond to the transition metal into which an olefin or diolefin can insert for coordination polymerization

Thus the unbndged monocyclopentadienyl metallocene compounds of the present invention can be represented by the foimula

CpJQ' ^Q M

wherein:

M is Zr, Hf or Ti;

Cp is a bulky cyclopentadienyl ring which is substituted with from two to five substituent groups R, and each substituent group R is, independently, a radical selected from hydrocarbyl, silyl or germyl radicals having from 1 to 20 carbon, silicon or germanium atoms, substituted hydrocarbyl, silyl or germyl radicals as defined wherein one or more hydrogen atoms is replaced by a halogen radical, an amido radical, a phosphido radical, an alkoxy radical, an aryloxy radical or any other radical containing a Lewis acidic or basic functionality; C, to C ₀ hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from the Group IV A of the Periodic Table of Elements; halogen radicals; amido radicals; phosphido radicals; alkoxy radicals; or alkylborido radicals; or, Cp is a cyclopentadienyl ring in which at least two adjacent R-groups are joined together and along with the carbon atoms to which they are attached form a C , to C,, ₀ ring system which may be saturated, partially unsaturated or aromatic, and substituted or unsubstituted the substitution being of one or more R group as defined above;

J is the substituted, bulky Group 15 heteroatom ligand which is substituted with two substituent groups R , and each substituent group Rl is, independently, a radical selected from hydrocarbyl, silyl or germyl radicals having 1 to 20 carbon, silicon or germanium atoms, substituted hydrocarbyl, silyl or germyl radicals as defined wherein one or more hydrogen atoms is replaced by a halogen radical, an amido radical, a phosphido radical, an alkoxy radical, or an aryloxy radical; C3 to C20 hydrocarbyl- substituted metalloid radicals wherein the metalloid is selected from the Group IV A of the Periodic Table of

Elements, halogen radicals, amido radicals, phosphido radicals; alkoxy radicals; or alkylboπdo radicals; and,

each Q is independently a radical selected from halide, hydnde; substituted or unsubstituted C, to C , ₀ hydrocarbyl; alkoxide, aryloxide; amide, halide or phosphide; or both Q together may be an alkyhdene or a cyclometallated hydrocarbyl or any other divalent anionic chelating hgand, with the proviso that where any Q is a hydrocarbyl radical, such Q is not a substituted or unsubstituted cyclopentadienyl radical

Such compounds can also include an L _w complexed thereto wherein L is a neutral Lewis base such as diethylether, tetrahydrofuran, dimethylanihne, aniline, tnmethylphosphine, n-butylamine, and the hke; and "w" is a number from 0 to 3

The term "cyclopentadienyl" refers to a 5-member πng having delocahzed bonding within the nng and typically being bound to M through η°-bonds, carbon typically making up the majontv of the 5-member positions.

Examples of the unbndged monocyclopentadienyl metallocene compounds of the invention include pentamethylcyclopentadienyltitaniumbistπmethylsilylamido dichlonde, tetramethylcyclopentadienyltitaniumbistnmethylsilyl-amidodic hlonde, pentaphenylcyclopentadienyltitamum bistπmethylsilylamidodichlonde, pentabenzylcyclopentadienyl titaniumbistnmethylsilylamidodichlonde, tetraphenyl- cyclopentadienyltitaniumbistπmethylsilylamidodichlonde, tetraphenylcyclopentadienyltitaniumbistπmethylsilylamido dichlonde, bistnmethylsilylcyclopentadienyltitanium bistπmethylsilylamidodichlonde, tnstnmethylsilylcyclopentadienyl titaniumbistπmethylsilylamidodichlonde, tπmethylsιlyl,t- butylcyclopentadienyltitaniumbistrimethylsilylamidodichlonde , bist-butylcyclopentadienyltitaniumbistπmethylsilylamidodich londe, indenyltitaniumbistπmethylsilylamidodichloride,

2-phenyhndenyltιtanιumbιstπmethylsιlylamιdodιchlo� �de, 2,4-dιphenyhndenyltιtanιumbιstπmethylsιlylamιdodιchl oιιde,

2-methyhndenyltιtanιumbιstnmethylsιlylamιdodιchloπde,

2-methyl,4-phenyhndenyltιtanιumbιstnmethylsιlylamιdo dιchlorιde, fluorenyltitaniumbistπmethylsilylamidodichloπde, pentamethyl cyclopentadienyltitaniumtnmethylsilyltnphenylsilylamidodichl onde, tetramethylcyclopentadienyltitaniumtπmethylsilyltπphenylsi lyl amidodichlonde, pentaphenylcyclopentadienyltitaniumtnmethyl- silyltπphenylsilylamidodichloπde, pentabenzylcyclopentadienyl- titamumtnmethylsilyltnphenylsilylamidodichloride, tetraphenylcyclopentadienyltitaniumtπmethylsilyltriphenvlsi lyl- amidodichlonde , tetraphenylcyclopentadienyltitaniumtπmethylsilyl tnphenylsilylamidodichloπde, bistnmethylsilylcyclopentadienyl- titaniumtnmethylsilyltnphenylsilylamidodichloride, tnstnmethylsilylcyclopentadienyltitaniumtnmethylsilyl- tnphenylsilylamidodichlonde, tnmethylsilyl.t-butylcyclopentadienyl titaniumtnmethylsilyltnphenylsilylamidodichloride, bistbutylcyclopentadienyltitaniumtrimethylsilyltπphenylsily l- amidodichlonde, mdenyltitaniumtrimethylsilyltriphenvlsilyl- amidodichlonde, 2-phenyhndenyltιtanιumtnmethylsιlyltrιphenyl-sιlylamιd odιchlonde,

2,4-dιphenylιndenyltιtanιumtπmethylsιlyl- tπphenylsilylamidodichlonde,

2-methyhndenyltιtanιum tnmethylsilyltriphenylsilylamidodichloπde,

2-methyl,4-phenyl- lndenyltitaniumtπmethylsilyltπphenylsilylamidodichlonde, fluorenyltitaniumtnmethylsilyltriphenylsilylamidodichloride, pentamethylcyclopentadienyltitaniumbistnphenylsilylamido-dic hlonde, tetramethylcyclopentadienyltitaniumbistriphenylsilyl- amidodichlonde, pentaphenylcyclopentadienyltitaniumbistnphenyl- silylamidodichloπde, pentabenzylcyclopentadienyltitamumbis- tπphenvl silylamidodichloπde, tetraphenylcyclopentadienyltitanium- bistnphenylsilylamidodichlonde, tetraphenylcyclopentadienyl- titaniumbistπphenylsilylamidodichloπde, bistnmethylsilylcyclopen- tadienvltitaniumbistπphenylsilylamidodichlonde,

tnstnmethylsilylcyclopentadienyltitaniumbistriphenylsilyl-am idodichlonde, tnmethylsrlyl, t-butylcyclopentadienyl- titamumbistnphenylsilylamidodichloride, bist-butyl cyclopentadienyltitaniumbistnphenylsilylamidodichlonde, mdenyltitaniumbistnphenylsilylamidodichloπde,

2-phenyhndenyltιtanιumbιstnphenylsιlylamιdodιchlond e, 2,4-dιphenyhndenyltιtanιumbιstπphenylsιlylamιdodιchl onde, 2-methyhndenyltιtanιumbιstnphenylsilylamιdodιchlonde, 2-methyl,4-phenyhndenyltιtanιumbιstnphenylsιlylamιdodι chlonde, fluorenyltitamumbistnphenylsilylamidodichlonde, pentamethylcyclopentadienyltitamumbistnisopropylsilyl-amidod ichlonde, tetramethylcyclopentadienyltitaniumbis- tnisopropylsilylamidodichlonde, pentaphenylcvclopentadienyl- titaniumbistπisopropylsilylamidodichlonde, pentabenzyl- cyclopentadienyl titaniumbistnisopropylsilylamidodichlonde, tetraphenylcyclopentadienyltitaniumbistnisopi o ylsilylamido-dichlonde, tetraphenylcyclopentadienyltitaniumbistnisopiopylsilyl- amidodichlonde, bistnmethylsilvlcyclopentadienyltitamumbistrnso- propylsilylamidodichlonde, tπstnmethylsilylcyclopentadienyl- titaniumbistnisopropylsilylamidodichlonde, tnrnethylsilyl.t- butylcyclopentadienyltitaniumbistnisopropylsilylamidodichlor ide, bist-butylcyclopentadienyltitaniumbistrnsopropylsilylamido- dichlonde, lndenyltitaniumbistπisopropylsilylamidodichloride, 2-phenylιndenyltιtamumbιstπιsopropylsιlylamιdodιchlo nde

2,4-d phenylιndenyltιtanιumbιstπιsopropylsιlylamιdodιchlo πde, 2-methylιndenyltιtanιumbιstrιιsopropylsιlylamιdodιc hlonde, 2-methyl,4-phenyhndenyltιtanιumbιstmsopropvlsιlyl amidodichlonde, fluorenyltitaniumbistrusopropylsilylamidodichloπde, pentamethylcyclopentadienyltitaniumtπisopiopyltπmethylsilv l- amidodichlonde, tetramethylcyclopentadienyltitaniumtπisopropyl- tnmethylsilylamidodichlonde, pentaphenylcyclopentadienyl- titaniumtnisopropyltnmethylsilylamidodichlonde, pentabenzylcyclopentadienyltitaniumtrnsopropyltrimethvlsilvl amidodichlonde,

tetraphenylcyclopentadienyltitaniumtriisopropyl- trimethylsilylamidodichloride, tetraphenylcyclopentadienyltitanium- triisopropyltrimethylsilylamidodichloride, bistriniethylsilylcyclo- pentadienyltitaniumtriisopropyltrimethylsilylamidodichloride , tristrimethylsilylcyclopentadienyltitaniumtriisopropyltrimet hylsilyl- amidodichloride, trimethylsilyl, t-butylcyclopentadienyl- titaniumtriisopropyltrimethylsilylamidodichloride, bist-butyl-cyclopentadienyltitaniumtriisopropyltrimethylsily lamidodichloride, indenyltitaniumtriisopropyltrimethylsilylamidodichloride, 2-phenyhndenyltitaniumtriisopropyltrimethylsilylamidodichlor ide, 2,4-diphenyhndenyltitaniumtriisopropyltrimethylsilyl amidodichloride, 2-methylindenyltitaniumtriisopropyltrimethylsilyl- amidodichloride, 2-methyl,4-phenylindenyltitaniumtriisopropyl- trimethylsilylamidodichloride, fluorenyltitaniumtriisopropyltrimethylsilylamidodichloride, pentamethylcyclopentadienyltitaniumbistributylsilylamidodich loride, tetramethylcyclopentadienyltitaniumbistributylsilylamidodich loride, pentaphenylcyclopentadienyltitaniumbistributylsilylamidodich loride, pentabenzylcyclopentadienyltitaniumbistributylsilylamidodich loride, tetraphenylcyclopentadienyltitaniumbistributylsilylamidodich loride, tetraphenylcyclopentadienyltitaniumbistributylsilylamidodich loride, bistrimethylsilylcyclopentadienyltitaniumbistributylsilylami do-dichloride, tristrimethylsilylcyclopentadienyltitaniumbistributylsilyl-a midodichloride, trimethylsilylt-butylcyclopentadienyltitaniumbistributylsily lamidodichloride, bist-butylcyclopentadienyltitaniumbistributylsilylamidodichl oride, indenyltitaniumbistributylsilylamidodichloride, 2-phenylindenyltitaniumbistributylsilylamidodichloride,

2,4-diphenyhndenyltitanιumbistributylsilylamidodichlorid e, 2-methylindenyltitanιumbistributylsilylamidodichloride, 2-methyl,4-phenylindenyltitaniumbistributylsilylamιdodichlo ride, fluorenyltitaniumbistributylsilylamidodichloride.

Substituted versions where a hydride, hydrocarbyl, germyl or silyl group replaces one or both chlorides are suitable in accordance with invention particularly where ionizing anion precursors are activators Separate or m situ alkylation is typical, e.g., dimethyl replacing dichlonde

A generic characteπzmg feature of these invention compounds is the inclusion of the bulky substitution on both of the cyclopentadienyl and amido ligands. It is beheved that the inclusion of these bulky substituents provides kinetic stability so that the active metal center is stabilized to the high temperature reaction conditions preferably employed Thus the inclusion of five methyl groups on the Cp nng with two tnmethylsilyl groups on the amido group sufficiently stabilizes an unbndged monocyclopentadienyl titanium compound such that it approaches the temperature stability of the bridged monocyclopentadienyl titanium compounds typically said to be the preferred, highly preferred and most highly prefeired compounds in pnor art discussions, see for example, U.S patents 5,064,802 and 5,321, 106

The unbndged monocyclopentadienyl metallocene compounds according to the invention may be activated for olefin polymeπzation catalysis in any manner sufficient both to remove or complex one Q group such that the metal center becomes sufficiently electron deficient to attract olefinically unsaturated monomers and such that the other Q bond is either itself, or is abstracted and substituted with another Q bond, sufficiently weak so as to permit insertion of it into the olefinically unsaturated monomer to yield a growing polymer, in the manner of traditional coordination/insertion polymeπzation The traditional activators of metallocene polymerization art are suitable, those typically include Lewis acids such as aluminum alkyls or alumoxane compounds, and ionizing anion pre-cursors that abstract one Q so as ionize the metal center into a cation and provide a counter-balancing noncoordinatmg anion.

The term "noncoordinatmg anion" means an anion which either does not coordinate to said transition metal cation or which is only weakly coordinated to said cation thereby remaining sufficiently labile to be displaced by a neutral Lewis base "Compatible" noncoordinatmg anions are those which are not degraded to neutrality when the initially formed complex

decomposes Further, the anion will not transfer an anionic substituent or fragment to the cation so as to cause it to form a neutral four coordinate metallocene compound and a neutral by-product from the anion. Noncoordinatmg anions useful in accordance w th this invention are those which are compatible, stabilize the metallocene cation the sense of balancing its ionic charge in a +1 state, yet retain sufficient lability to permit displacement by an ethylenically or acetylenically unsaturated monomer dunng polymenzation Additionally, the anions useful in this invention will be large or bulky in the sense of sufficient molecular size to largely inhibit or prevent neutrahzation of the metallocene cation by Lewis bases other than the polymenzable monomers that may be present m the polymeπzation process Typically the anion will have a moleculai size of greater than or equal to about 4 angstroms

Descriptions of ionic catalysts for coordination polymenzation compnsed of metallocene cations activated by ionizing anion pre-cursors appear in the early work in EP-A-0 277 003, EP-A-0 277 004, L S patents 5, 198,401 and 5,278, 119, and WO92/00333 These teach a preferred method of preparation wherein metallocenes (bis Cp and mono Cp) are protonated by an anionic precursors such that an alkyl hydnde group is abstracted from a transition metal to make it both cationic and charge-balanced by the non¬ coordinatmg anion The use of ionizing ionic compounds not cont aining an active proton but capable of producing the both the active metallocene cation and an noncoordinatmg anion is also known See, EP-A-0 426 63 7, EP-A- 0 573 403 and U S patent 5,387,568 Reactive cations other than Bronsted acids capable of ionizing the metallocene compounds include ferrocenium tnphenylcarbomum and triethylsilyhnium cations Any metal or metalloid capable of forming a coordination complex which is lesistant to degradation by water (or other Bronsted or Lewis Acids) may be used or contained in the anion of the second activator 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, silicon and the hke The descnption of non-coordinating anions and precursors thereto of these documents are incorporated by reference for purposes of U S pateni practice.

An additional method of making the ionic catalysts uses ionizing anion pre-cursors which are initially neutral Lewis acids but form the cation and anion upon ionizing reaction with the metallocene compounds, for example t.rιs(pentafhιorophenyf) boron acts to abstract an alkyl, hydiide or silyl Hgand to yield a metallocene cation and stabilizing non -coordinating anion, see EP- A-0 427 697 and EP-A-0 520 732. Ionic catalysts for addition polymerization can also be prepared by oxidation of the metal centers of transition metal compounds by anionic precursors containing metallic oxidizing groups along with the anion groups, see EP-A-0 495 375. The description of non¬ coordinatmg anions and precursors thereto of these documents are similarly incorporated by reference for purposes of U.S. patent practice.

Examples of suitable anion precursors capable of ionic catiomzation of the metallocene compounds of the invention, and consequent stabilization with a resulting noncoordinatmg anion include tnalkyl-substituted ammonium salts such as: triethylammonium tetra(phenyl)boron, tnpropylammonium tetra(phenyl)boron, tri(n-butyl)ammonιum tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, tnmethylammonium tetra(o-tolyl)boron, tnbutylammonium tetra(pentafluorophenyl)boron, tnpropylammonium tetra (o,p-dιmethylphenyl)boron, tnbutylammonium tetra(m,m-dιmethylphenyl)boron, tributylammomum tetra(p-trifluoromethylphenyl)boiOn, tributylammonium tetra(pentafluorophenyl)boron, tri(n-butyl)ammonιum tetra (o-tolyl)boron and the hke;

N,N-dιalkyl anihnium salts such as: N,N-dιmethylanιlmium tetra(phenyl)boron,

N,N-dιethylanιlιnιum tetra(phenyl)boron,

N,N-dιethylanιhnιum tetra(phenyl)n-butylboron,

N,N-2,4,6-pentamethylanιhnιum tetra(phenyl)boron and the like; dialkyl ammonium salts such as: di-(ιsopropyl)ammonιum tetra(pentafluorophenyl)boiOn, dicyclohexylammomum tetra (phenyl)boron and the like; and tnaryl phosphomum salts such as

triphenylphosphonium tetra)(phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron, tri(dimethylphenyl)phosphonium tetra(phenyl)boron and the hke.

Further examples of suitable anion precursors include those comprising a stable carbonium ion, and a compatible non-coordinating anion. These include: tropiUium tetrakispentafluorophenyl borate, triphenylmethyhum tetrakispentafluorophenyl borate, benzene (diazonium) tetrakispentafluorophenyl borate, tropillium phenyltris-pentafluorophenyl borate, triphenylmethyhum phenyl-trispentafluorophenyl borate, benzene (diazonium) phenyltrispentafluorophenyl borate, tropillium tetrakis (2,3,5,6-tetrafluorophenyl) borate, triphenylmethyhum tetrakis (2,3,5,6-tetrafluorophenyl) borate, benzene (diazonium) tetrakis (3,4,5-trifluoiOphenyl) borate, tropilhum tetrakis (3,4,5-trifluorophenyl) borate, benzene (diazonium) tetrakis (3,4,5-trifluorophenyl) borate, tropillium tetrakis (3,4,5-triϋuorophenyl) aluminate, triphenylmethyhum tetrakis (3,4,5-trifluorophenyl)aluminate, benzene (diazonium) tetrakis (3.4.5-trifluorophenyl) aluminate, tropilhnum tetrakis (1,2,2-trifluoroethenyl) borate, triphenylmethyhum tetrakis (1,2,2-trifluoroethenyl) borate, benzene (diazonium) tetrakis (1,2,2-trifluoroethenyDborate, tropillium tetrakis (2,3,4,5-tetrafluoiOphenyl)borate, triphenylmethyhum tetrakis (2,3,4,5-tetrafluorophenyl)borate, benzene (diazonium) tetrakis (2,3,4,5-tetrafluorophenyl) borate, etc.

Where the metal ligands include Q halide moieties, such as in (pentamethyl cyclopentadienyl) (ditrimethylsilyl amido) titanium dichloride, which are not capable of chscrete ionizing abstraction under standard conditions, these moieties can be converted via known alkylation reactions with organometallic compounds such as lithium or aluminum hydrides or alkyls, alkylalumoxanes, Grignard reagents, etc. See EP-A-0 500 944, EP- Al-0 570 982 and EP-A1-0 612 768 for processes describing the reaction of

alkyl aluminum compounds with dihalide substituted metallocene compounds prior to or with the addition of activating anion precursor compounds

Known alkylalumoxanes are additionally suitable as catalyst activators, particularly for the invention metal compounds compnsing the halide hgands The alumoxane component useful as catalyst activator typically is an ohgomenc aluminum compound represented by the general formula (R-Al-O) , which is a cychc compound, or R(R-Al-O) _n AlR ₀ , which is a linear compound In the general alumoxane formula R is a C _t to C 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 Alumoxanes can be prepared by various procedures known m the art For example, an aluminum alkyl may be treated with water dissolved m 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 alumoxane. Generally, however prepared, the reaction of an aluminum alkyl w th a limited amount of water yields a mixture of the linear and cychc species of the alumoxane

When using ionic catalysts comprising unbndged Group 4 metal cations and non-coordinating anions, the total catalyst system will generally additionally comprise one or more scavenging compounds The term "scavenging compounds" as used m this application and its claims is meant to include those compounds effective for removing polar impurities from the reaction solvent Such impurities can be inadvertently introduced with any of the polymerization reaction components, paiticulaiiy with solvent, monomer and catalyst feed, and adversely affect catalyst activity and stability It can result in decreasing or even elimination of catalytic activity, particularly when a metallocene cation-noncoordmatmg anion pair is the catalyst system The polar impunties, or catalyst poisons include water, oxygen, metal impurities, etc Preferably steps are taken before provision of such into the reaction vessel, for example by chemical treatment or careful separation techniques after or durmg the synthesis or preparation of the vaπous components, but some minor amounts of scavenging compound will still normally be required m the polymerization process itself Typically the scavenging compound will be an organometalhc compound such as the

Group-13 organometalhc compounds of 5, 153, 157, 5,241,025, EP-A- 638 and WO-A-91/09882 and WO-A-94/03506, noted above, and that of WO-A- 93/14132. Exemplary compounds include tnethyl aluminum, tnethyl borane, tri-isobutyl aluminum, tπ-isobutyl aluminumoxane, and tn-n-octyl aluminum, those having bulky substituents covalently bound to the metal or metalloid center being preferred to minimize adverse interaction with the active catalyst When an alkyl aluminum or alumoxane is used as activator, any excess over the amount of metallocene present will act as scavenger compounds and additional scavenging compounds may not be necessary. The amount of scavenging agent to be used with metallocene cation- noncoordinating anion pairs is minimized during polymerization reactions to that amount effective to enhance activity In the process descnbed in this invention, it was found that there is an optimum contact time between the scavenger compound and the reaction mixture to maximize catalyst activity. If the contact time is too long, detrimental catalyst deactivation might occur.

The high temperature solution process for the production of the EPC elastomers or plastomers, or ethylene copolymers, in accordance with this invention improves process economics and increases product capabilities. For process economics, the combination of high reactor temperature and solvent recovery systems brings significant cost improvements. The improved economics of the high temperature solution process compared with the conventional process is related to the operation of polymenzation reactor at higher polymer concentration than conventional solution process The higher polymer concentrations are possible due to improvement m the solution viscosity at higher temperatures A high reactor exit temperature improves the efficiency of the solvent recovery systems resulting in improved recycling economics. High efficiency recycling systems are crucial in considering the future of solution based processes m comparison with the competitive options, such as gas phase In addition, efficien t solvent recychng also reduces the environmental impact of the process with respect to volatile organic compound emissions to meet increasingly more lestnctive regulatory levels Additionally, the use of the invention process allows for high diolefin conversion from monomer to incorporated mer unit in the polymer, thus reducing cost of separation and recycle Typical conversion ratios of diolefin monomer can range from 20%, 30% or up to as high as 40%, and higher.

The polymenzation process of the invention involves contacting the polymenzable monomers (ethylene, α-olefin and, optionally diene monomer) in solution with the described ionic catalyst system, preferably at high reaction temperatures, from about 80 °C to 160 °C or above, and is suitably conducted in the following manner The solvent is heated to reaction temperature prior to introduction into the reaction vessel The solvent is then provided to the reaction vessel after polymenzable monomer is introduced in either hquid, gas or solution form into that reaction solvent. A reaction medium is formed compnsing the solvent with which the catalyst system and monomers are contacted foi the polymerization reaction Typically, the scavenging compound is introduced into the reaction solvent to reduce or eliminate catalyst poisons present in any of the reaction medium components pnor to introduction into the reactor If the scavenging compound and activator aie different, and contacted with each other for sufficient time, adverse effects on the effectiveness of that activator might occur In this piocess, the activator and metallocene compound are contacted in the polymerization reaction vessel in the presence of the polymenzable monomers, compnsing the in-situ activation

Typically the reaction is conducted at pressures from atmosphenc to 500 psig (1-35 bar), preferably from 100 to 300 psig (8 to 21 bar) Preferred reaction temperatures aie above 80 °C, moie preferably at or above 100 °C, for instance 110 °C and above Piefeiably the upper limit to the reaction temperature m this solution process is not gi'eater than 160 °C, preferably 150 °C Typically the polymeπzation reaction will be exothermic and the reactor will be chύled or cooled in accordance with known methods to assure that temperatures do not exceed those reasonably suitable for the polymer being produced

The feedstock purification prior to introduction into the leaction solvent follows standard practices in the art, e g molecular sieves, alumina beds and oxygen removal catalysts are used for the purification of ethylene, α-olefin, and optional diene The solvent itself as well, e g , hexane and toluene, are similarly treated Punfication of the dienes was observed to increase diene conversion, best results weie obtained when the diene was fractionally distilled with CaH ₂ as the purification method

The α-olefin monomer(s) and diene monomer(s), if included, are introduced m an amount proportional to the levels of incorporation desired for the polymer to be produced and the effective reactive ratios for the polymenzable monomers in the presence of the specific catalyst chosen. In the preferred embodiment the combination of the α-olefin monomer(s) in reaction solvent as introduced into the reactor and effective vapor pressure of the α-olefin monomer(s) is maintained according to the rate of incorporation into the copolymer product In an alternative embodiment, the partial pressure in the reactor will be provided by ethylene alone in which situation the α-olefin monomer(s) are added solely with reaction solvent The amounts and vapor pressure will vary according to catalyst selection and polymer to be produced, but can be empirically determined well withm the skill in the art, particularly in view of the description provided in the following examples

The catalyst activator, e g , non-coordmatmg anion precursor, ionizing anionic precursor, or alumoxane, can be introduced along with or separately from introduction of the optional diolefin monomeι(s), if used The diolefin can be provided in an amount effective for its rate of reaction and rate of conversion The catalyst activator can be provided in an amount that is equal to 0.2 to 10 molar equivalents of the Group 4 metallocene compound, preferably 0 25 to 5, and even moie prefeiably 0 33 to 3 0, when a noncoordinatmg anion precursor Typically the provision of the noncoordinatmg anion precursor activator will be in an effective solvent, typically an aromatic solvent such as toluene When the activator is alumoxane, it can be used in an amount that is equal to 0 5 to 10,000 molar equivalents of the metallocene compound, prefeiably 0 75 to 5000, and even more preferably 1 0 to 500 Preferably the alumoxane will be used in an amount empirically determined to suffice for concu ient removal of impurities and activation, but only in such amounts as necessary to accomphsh those functions Monitoi g of polymerization activity by known methods will permit on-hne adjustment of alumoxane to assure neither excess nor deficit amounts are maintained for unwanted periods.

The scavenging compounds are provided separately afterwards or with one of the foregoing feedstreams, in an amount suitable to increase the activity of the catalyst but in an amount lowei than that at which depression

of reactivity is observed TypicaDy an effective amount of the scavenging compound is about 0 (e g , with an alumoxane activator) to 100 mol ratio based upon the ratio of scavenging compound to activator, preferably the ratio is 0.3 to 30, and most preferably it is 0 5 to 10

Promptly thereafter, preferably within not more than about 1 minute, more preferably within 30 seconds, the metallocene compound is contacted with the activator in the presence of the polymenzable monomers so as to hmit the residence time of the scavenging compound with the activator The metallocene is typically provided m an aliphatic or aromatic solvent, which can be any of those suitable as polymerization medium For ease of reference the examples below refer to the metallocene in solvent as "catalyst solution". Though any order of activation will have at least some suitability, the order of addition described herein is particularly suitable for use with ionizing activators that provide the stabilized metallocene cation-noncoordmatmg anion pair Since alumoxane can act as a suitable scavenger compound, its addition as activator in accordance with the described process ehminates the need to introduce a scavenger and the preference for hmited time of contact between scavenger and activator is largely eliminated so long as the addition of the metallocene to activator containing solution is in the presence of polymenzable monomers In this manner premature activation can be avoided

Ethylene gas is then provided into the reaction vessel in an amount proportional to the level of incorporation desired and the effective reactive ratios for the polymenzable monomers in the presence of the specific catalyst chosen, as with the α-olefin monomer(s) The polymenzation starts upon contact of the monomers with the activated catalyst and the rates of supply of each of the components of the system aie adjusted for stable operations at the level of production, molecular weight, monomei incorporation and equipment limitations. The reaction temperature may be permitted to exceed the initial temperature but will preferably be at all times greater than the lower limit of the ranges descnbed above for the invention process

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 (C _a to C _j , aliphatic solvent, Exxon Chemical Co , U.S.) Preferably the solvent is aliphatic, most preferably it is hexane.

Though not stnctly necessary for the solution polymenzation process as descnbed, the catalyst according to the invention may be supported for use in alternative gas phase, bulk, or slurry polymerization processes where the high temperature benefits of the catalysts are sought to be applied. Numerous methods of support are known in the art for copolynienzation processes for olefins, particularly for catalysts activated by alumoxanes, any is suitable for the invention process m its broadest scope. See, for example, U.S patent 5,227,440 An example of supported ionic catalysts appears in WO 94/03056 When using a Lewis acid ionizing catalyst activator a particularly effective method is that descnbed in WO 96/04319 The support method of this co-pending application describes the use of a Lewis acid noncoordinatmg anion precursor (e g , tπsperfluorophenyl boron) which is covalently bound to sihca-containing supports through retained hydroxy groups which as an initially formed activator complex donates the hydroxyl hydrogens as protons for protonation of the Group 4 transition metal compound to catalytically active cations A bulk, or slurry, process utilizing supported, fciscyclopentadienyl Group 4 metallocenes actival ed with alumoxane co-catalysts is described as suitable foi EPM and EPDM in U.S. patents 5,001,205 and 5,229,478, these processes will additionally b s suitable with the catalvst systems of this application Each of the foregoing documents is incorporated by reference for purposes of U.S. patent practice. In these examples ENB represents 5-ethyhdene-2-norbornene IPA is isopropyl alcohol, GPC is gel permeation chromatography, TIBAL is tnisobutyl aluminum.

Though the Examples and the discussion are directed to a single reactor configuration and narrow polydispersity polymers, it is well-known that the use in series of two such reactois each operated so as to achieve different polymer molecular weight characteristics, or by blending polymers from different reactor conditions or utilizing two or more different transition metal catalysts in one or more reactors, can yield improved processing polymers. The disclosures of U S patent 4,722,971 and WO 93/21270 are instructive and are incorporated for purposes of U S patent practice Though

directed to the use of vanadium catalysts, the substitution of the catalyst systems of this invention into one such reactor, or two different invention catalysts into two such reactors, or similar use in two separate polymenzations with subsequent physical blending of the polymer products, will permit tailonng of characteristics (e g , molecular weights and diene contents) suitable for balancing vulcanization properties with processabihty. Similarly, the use of mixed catalyst systems, the invention catalysts with themselves or with others, in one or oie such reactors will permit preparation of bimodal or multimodal EPC polymers having improved processing properties.

The following examples are presented to illustrate the foregoing 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 to be viewed as limiting the invention in any specific respect Methods of determining M _n and monomer contents by NMR and GPC for the illustrative EPDM examples of the invention are descnbed in U.S. patent 5,229,478 which is incorporated by reference for purposes of U.S patent practice For measurement of comonomer contents in the EPC elastomers, the method of ASTM D3900 for ethylene-propylene copolymers between 35 and 85 wt % ethylene was used. Outside that range the NMR method was used See also, U S patent 4,786,697 which is incorporated by reference for purposes of U S patent practice.

EXAMPLES

Example 1- Synthesis of EPDM

The polymerizations were conducted in a 500 cc autoclave reactor operated at the temperature of 115 °C in the batch mode for the polymer and semi-batch for the ethylene monomer The following proceduie was used for the polymerizations

The reactor was charged with 250 cc of purified hexane, 5 cc of 10 wt.% toluene solution of MAO (activator) and 3 cc of purified ENB (fractional distillation with CaH2).

The reactor was heated to 115 °C, resulting in a hexane vapor pressure of approximately 37 psig (2.5 bar).

Propylene was added to the reactor to reach 1 10 psig (7.48 bar) pressure (liquid phase molar cone. = 0.856M).

Ethylene was added to the reactor to reach 235 psig (16 bar) pressure (liquid phase cone. = 0 87 IM ). These conditions determined the intial ethylene/propylene molar ratio equal to 1 018. The ethylene/ENB molar ratio was 10.43.

The catalyst solution was pumped to the reactor to maintain the polymerization rate constant as indicated by the make-up flow rate of ethylene to the reactor. The pumping was adjusted to keep this rate at about 0.1 SLPM (standard L/min, standard conditions 1 bar, 21.1 °C), to target approximately lOg yield of polymer.

Irganox® 1076 was added to the hexane solution to the final concentration of 0 1 mg/cc to prevent sample degradation. The polymers were worked-up from the solution by precipitation w th 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 were done by H-NMR for ENB content and GPC for EPDM molecular weight.

Table 1: Results for Example 1

Catalyst: pentamethylcyclopentadienylbis- trimethylsilylamidotitanium dichloride

Activator: methylalumoxane

Temperature 115 °C

Pressure: 235 psig

Example 2: Synthesis of EPDM

The same procedure as described in Example 1 was carried out with the noncoordinatmg 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 ^J M of the activator solution in toluene was added. The reactor was then heated up to 115 °C, as in Example 1.

To the pressurized reactor after the addition of ethylene, 10 microhters of 2M TIBAL solution in pentane was added as the scavenger at least one minute before the start of the catalyst pumping.

Table 2: Results for Example 2

Comparative Example 2: Synthesis of EPDM

The same procedure as described in Example 2 was carried out the following catalyst:

Table 3: Results for Comparative Example 2

Catalyst: cyclopentadienylbis-trimethylsilylamidotitanium dimethyl Activator: dimethylanihnium tetra(peιfluorophenyl) borate Temperature 115 °C Pressure: 235 psig

Comparative Example 2 illustrates the requirement of bulky Cp hgands to the titanium catalyst for improvement of molecular weights. The M _n for the pentamethylcyclopentadienyl substituted catalyst was at least 10 times higher than for the cyclopentadienyl substituted catalyst of JA 94-80683.