USE OF SILICATE AS CHAIN BRANCHING SUPPRESSOR IN EPDM PRODUCTION

Abstract: In a process for the preparation of an EPDM using a vanadium catalyst and an aluminum compound cocatalyst, branching is suppressed without loss of catalyst efficiency or propylene conversion by utilizing as the branching suppres­ sor a silicate of the formula. Si(OR) x L y wherein R is hydrocarbyl, L is halogen, hydrogen or R, x is 3 or 4 and y - 4-x.

Description: SILICATE MOLLIFIED EPDM CATALYST SYSTEM AND PROCESS Useful polymers of ethylene and propylene include the terpolymers of ethylene and propylene with a non-conjugated diene. These polymers which have incorporated therein a site of pendant unsaturation are commonly known as EPDM polymers. They have wide utility because, unlike the ethylene-propylene copolymers (EP) the EPDX polymers can be sulfur crossed linked. This characteristic is attributable to the presence of unsaturation which is lacking in the EP polymers. While unsaturation is a desirable property in the EPDM from the standpoint of utility it is the source of problems during polymerization. An idealized EPDfl polymer Es devoid of any branching other than the moomeric moieties attached to the EP backbone chain as sites of pendant unsaturation. In practice, however, these sites of unsaturation are points of initiation for branching as a result of chain coupling. While a wide range of chemical reactions can result in branching, it is especially likely when the residual olefin of the pendant group is capable of forming a tertiary carbonium ion and the Ziegler catalyst system employed to produce the polymer has considerable Lewis acid character. The branching is believed to be catalyzed by cationic species arising from the Ziegler catalyst. Olefin functionality that can form a secondary carbonium ion is also believed to be susceptible to branching in the presence of acidic catalyst, as well as olefin structures which can rearrange to tertiary or secondary ions. Consequently, for residual olefin functionality in the polymer of the generalized structure EMI2.1 where n#0 m; O R1, R2, R3, R4, R5, R6 " hydrogen, alkyl, cyclic or aromatic groups cationically catalyzed branching can be expected as long as n and m are not both zero when R1 and R4 are both Sy- drogen. Examples of the diene monomers that tend to form branched structures with acidic Ziegler catalysts are as follows: dicyclopentadiene 5-methylene-2-norbornene 5 -ethylidene-2-norbornene tetrahydroindene methyl tetrahydroindene 5 -isopropenyl-2 -norbornene 5- (2-butenyl) -2-norbornene 5-methallyl-2-norbornene 5-isopropylidene-2-norbornene 2-methyl-norbornadiene Excessive branching yields polymers with undesirably high bulk viscosity. Additionally, the corresponding vulcanizates have inferior physical properties. Furthermore, branching can also lead to unstable reactor operations during polymerization resulting in undesirable product quality variability. The Ziegler catalyst systems employed to produce ethylene copolymers and terpolymers generally com- prise a vanadium compound catalyst z and an aluminum com- pound cocatalyst. The preferred vanadium compounds of the prior art include halides, oxyhalides, and vanadates including dihalovanadates. British patent no.1132,662 discloses a suitable EP catalyst which utilizes a vanadium compound of the formula VX4 or VOX3 wherein X is halogen, alkyl, cycloalkyl or alkoxy. The vanadium compound is utilized in conjunction with a cocatalyst prepared by reacting an aluminum sesquihalide with an organic hydroxy compound. British patent no. 1,275,641 discloses a catalyst system for the preparation of polymers and copolymers of olefins which comprises a titanium or vanadium compound which can be a halide* oxyhalide or haloalkoxy compound of vanadium or titanium. The cocatalyst is a compound of the formula Xm-nM)OR=n, wherein X is a monovalent inorganic radical, R is a monovalent hydrocarbon radical, M is a metal belonging to Groups Ia, Ila, IIb, Ilib and Villa of the Periodic Table or boron, m is the valence of M and n is an integer such that 1#n#m. U.S. patent nc. 3,288,768 discloses the catalyst system for the production of copolymers of alphaolefins which comprises (1) a vanadium chloride or oxychloride, (2) an alkyl aluminum dihalide and (3) a dialkyl aluminum alkoxide. U.S. patent no 3,597,367 discloses a catalyst system for the preparation of alpha-olefin copolymers comprising a vanadium oxychloride or a vanadium halo alkoxy, an aluminum borohydride and a Lewis acid. U.S. patent no. 3,567,653 discloses a catalyst useful for the copolymerization of ethylene and higher alpha-olefine comprising an alkyl aluminum and the reaction product of a vanadium compound and an alkyl titanate. The vanadium compound can be VOC13 or an alkylvanadate. U.S. patent 3,780,005 discloses a similar catalyst wherein the catalyst is tha reaction product of a vanadium oxychloride or tetrachioride with an aluminum alkoxide. U.S. patent no. 3,048,574 discloses the preparation of an alpha-olefin polymerizatîon catalyst by reacting a Group I-VII compound with an organoxysilane, U.S. patent no. 3,271,37 discloses a catalyst system for the preparation of the reaction products of vanadium oxytrichloride or vanadium tetrachloride, an alkyl aluminum dihalide, and an alkoxy silane. None of these prior art catalyst systems can taining alkoxides are directed toward producing EPDM with reduced branching. It is known to reduce branching during ethylene terpolymer polymerization by the addition of a Lewis base, e.g. NH3, to the polymerization medium. While the Lewis base is effective to reduce branching it, too, reduces catalyst reactivity and efficiency. What is needed is a method for effectively eliminating branching during the preparation of ethylenelalpha. olefin/non-conjugated diolefin terpolymers while at the same time not otherwise changing the characteristics of the catalyst system being used. It has been surprisingly found that alkoxy silanes can be used as catalyst system modifiers to substantially reduce branching during ethylene terpolymer (EPDM) polymerization. Branching is suppressed without any effect on catalyst efficiency or reactivity. The catalyst used in EPDM polymerization is generally a vanadium halide or vanadium oxychloride. A cocatalyst is generally an alkyl aluminum halide, e.g., aluminum sesquihalide or dialkyl aluminum halide. The alkoxy silanes suitable for use as catalyst modifiers in the practice of this invention have the general formula Si (OR)xLy wherein x is 3 or 4, y - 4-x, R is a hydrocarbyl moiety and L is halogen, hydrogen or R. The amount of silicate required to effectively suppress branching will vary depending on polymerization conditions and catalyst system utilized. The mole ratio of silicate to aluminum is preferably about 0.02 to about 0.5 moles/mole. This invention relates to an improved process for the polymerization of EPDX polymers which are substantially free of branching. In particular it relates to a catalyst system modifier to suppress branching which comprises an alkoxy silane of the general formula Si (OR)xLy wherein L is halogen, hydrogen or R; R is hydrocarbyl group, x is 3 or 4 and y = 4 4-x. Preferably R is an alkyl, cycloalkyl or aromatic moiety. More preferably R is C1-C8 alkyl* C6-Clo cycloalkyl, or a C6-C12 aromatic moiety. Most preferably R is a C1-C4 alkyl moiety. Illustrative non-limiting examples of R are methyl, ethyl, n-propyl, sec-butyl, cyclohexyl, phenyl or mixtures thereof. The preferred halogen is chlorine. As used in the specification and claims the term "EPDM" means terpolymers of ethylene, an alphaolefin and a non-conjugated diene. The non-conjugated diolefin can be straight chain1 branched chain or cyclic hydrocarbon di-olefinsDreferably having 6 to 15 carbon atoms such as: A. straight chain acyclic dienes such as 1,4-hexadiene and 1,6-octadiene. B. branched chain acyclic dienes such as 5 methyl-l, 4-hexadiene; 3,7-dimethyl-1,6 octadiene; 3,7-dimethyl-l, 7-octadiene and the mixed isomer± of dihydro-myricene and dihydro-ocinene; C. single ring alicyclic dienes such as 1,3 cyclopentadiene; 1,4-cyclohexadienes 1.5- cyclo-octadiene and 1 ,5-cyclododecadiene; D. multi-ring alicyclic fused and bridged ring dienes such as tetrahydroindene, methyl. tetrahydroindene, dicyclopenta diene; bicyclo-(2,2,1)-hepta-2, 5-diene; alkenyl, alkylidene, cycloalkenyl and cycloalkylidene norbornenes such as 5 methylene-2-norbornene (MNB), 5-propenyl 2-norbornene, 5-isopropylidene-2-norbor nene, 5-(4-cyclopentyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, 5-vinyl 2-norbornene and norbornadiene. Of the non-conjugated dienes typically used to prepare EPDM terpolymers the preferred dienes are dicyclopentadiene, 1 ,4-hexadiene, 5-methyl-2-norbornene and 5 -ethylidene -2-norbornene. Particularly preferred diolefins are 5-ethylidene-2-norbornene (ENB) and 1,4 hexadiene EPDM elastomers and their general method of manufacture are well known in the art. The preferred EPDM elastomers contain about 20 to about 90 weight percent ethylene, more preferably about 30 to 80 weight percent ethylene, most preferably about 35 to about 75 weight percent ethylene. The alpha-olefins suitable for use in the preparation of EPDM are preferably C3-C16 alpha-olefins. Illustrative non-limiting examples of of such alphaolefins are propylene, 1-butene, 1-pentene, 1-hexene, l-octene and l-dodecene. The alpha-olefin is generally incorporated into the EPDM polymer at about 10 to about 80 weight percent, more preferably at about 20 to about 70 height per cent. The non-conjugated diene is preferably incorporated into the EPDM at about 0.5 to about 15 weight percent; more preferably about 1 to about 10 weight percent, e.g., 5 weight percent. In carrying out the process of this invention the preferred catalysts are vanadium compounds with a vanadium valence of at least 3, and which are soluble in the polymerization diluent; more preferably the catalysts are VX4 or an oxyvanadium compound of the general formula VOXn(OR')3-n where n is an interge: of 2 or 3, R' is a hydrocarbyl radical and X is halogen, preferably chlorine or bromine. Preferably R' is C1-C10 alkyl, phenyl or benzyl, more preferably R' is C1-C4 alkyl, e.g., methyl. ethyl or butyl. The cocatalyst utilized to prepare the active catalyst species is an aluminum compound such as A12R''3X'3 (alkylaluminum sesquihalides) or AlR"bX'3¯b, wherein R" is a hydrocarbyl moiety, Xl is halogen and b is 1 to 2. While the halogen can be chlorine, bromine or iodine, the preferred halogen is chlorine. The hydrocarbyl moiety can be eg C1-C20 alkyl1 cycloalkyl or aromatic group. Pref erably R" is C1-C10 aikyl or cycloalkyl, phenyl or benzyl. Most preferably R" is C1-C6 alkyl. Illustrative, non-limiting examples of R" are methyl, ethyl, n-propyl, iso-butyl, hexyl, cyclohexyl, phenyl or mixtures thereof. In its preferred embodiment the aluminum compound is a dialkyl aluminum halide or alkyl aluminum sesquihalide. More preferably the aluminum compound is diethyl aluminum chloride ("DEAC") or ethyl aluminum sesquichloride ("EASC"). While a wide range of diluents are known to be suitable for EPDM polymerization, the diluent is preferably an organic compound which is a solvent for the monomers and polymers as well as the vanadium compound. In utilizing the catalyst system of this invention the vanadum ,compound and aluminum compound can be utilized at a Al/V mole ratio of eg 1 to about 40, preferably about 2 to about 20, more preferably about 3 to about 10, e.g., 5 to about 10. The polymerization reaction can be conducted at a gage pressure of eg 0 Kpa to about 3000 Xpa and at any temperature suitable for Ziegler polymerization reactions. The preferred pressure range for carrying out the EPDM polymerization is about 100 to about 1500 Kpa, more preferably about 300 to about 1000 Kpa. The polymerization is preferably carried out at about -20 degrees C to about 150 degrees C, more preferably about 10 degrees C to about 100 degrees C, most preferably about 15 degrees C to about 60 degrees C. It is within the scope of this invention to incorporate hydrogen as a feed stream to moderate polymer molecular weight. The hydrogen is added at about 0 to about 30 mole percent based on the total monomer. The silicates of this invention can be utilized at lower concentration than the prior art branching suppressors and have the added advantage of allowing the use of less aluminum compound cocatalyst. The particular amount of silicate required to suppress branching will depend on the nature of the silicate, the diolefino the catalyst system, the Al/V ratio and the polymerization conditions. Generally eg 0.02 to 0.5 moles of silicate to moles of aluminum can be used; preferably about 0.04 to 0.3 mol/mol are used. The efficacious amount of silicate needed for a given set of polymerization conditions can readily be determined by experiments using the technique described in the exams pies, infra. Increasing amounts of silicate compound are added to the polmerization reactor and the degree of long chain branching in the polymer is measured. The silicate concentration that just reduces branching to a minimum is the optimurn amount. The use of excessive amounts of silicates will result in reduced catalyst activity. The silicate concentration can also be expressed in terms of Si/V mole ratio and can w=y eg from about 0.1 to about 3.0; preferably about 0.3 to about 2.0; more preferably about 0.6 to about 1.3, e.g. about 0.4 to about 1.0. The vanadium and aluminum compounds can be added to the reactor either separately or premixed with one another. However, it is preferred that the silicate be added to the reactor separately and not in combina tion with any of the catalyst components. The advantages of the instant invention may be more readily appreciated by reference to the following examples. In the examples the polymerization was carried out in a liquid filled, continuous, stirred tank polymerization reactor. Reactor residence time was 13 minutes and polymerization temperature was 32 degrees C unless otherwise specified. Ethylene, propylene and 5-ethylidene-2norbornene (ERK) were fed to the reactor in a hexane solution. Conventional precautions were taken to purify all reactor feed streams so that air, moisture, and other catalyst poisons did not enter the reactor in significant amounts. Catalyst, cocatalyst and silicate were pumped into the reactor as dilute solutions in hexane. Hydrogen was fed as a gas to control polymer molecular weight. At the exit of the reactor the polymerization was quenched by mixing water with the polymer solution. Polymer was recovered by adding the solution to a tank of hot water sparged with steam to strip off the solvent and unreacted monomers. The wet polymer was then dried on a hot rubber mill. Polymerization rate was determined by weighing the amount of rubber obtained in a fixed time period. Monomer conversion and catalyst efficiency (weight of polymer product/wt. vanadium catalyst fed) were determined to characterize the catalyst activity. Infrared analysis (ASZM D3900) was used to measure polymer ethylene content while refractive index (I.J. Gardner E G. Ver Strate, Rubber Chem Tech, 46, 1019 (1973)) was used for ENB content. Polymer Mooney viscosity was measured by ASTM-D1646. Molecular weight (number average, Mn; weight average, M; z average, Mz) and molecular weight distribution (lD,) were measured using a Waters 150 gel permeation chromatograph equipped with a Chromatix KlW-6 on-line light scattering photometer. The system is used at 135 degrees C with 1,2,4-trichlorobenzene as the mobile phase. Showadex (Showa-Denko America, Inc.) polystyrene gel columns 802, 803 804 and 805 were used. The technique utilized is described in Liquid Chromatography of Polymers and Related Materials III, J. Cazes, editor, Marcel Dekker, 1981, p. 257, incorporated herein by reference. No corrections for column spreading are employed; however, data on generally accepted standards, e.g., National Bureau of Standards Polyethylene 1484 and anionically produced bydroqenated polyisoprene demonstrate that such corrections on Mw/Mn or Mz/Mw are less than 0.05 units. Mw/Mn was calculated from an elution time-molecular weight relationship whereas .1z/Mw is evaluated using the light scattering photometer. The MW/Mn are used as an indication of MWD breadth (the larger the value, the broader the MWD). The degree of branching in the EPDM was ascertained by measuring the solubility of non-crystalline terpolymer samples. Polymers with no or low amounts of branching will dissolve completely in hexane at 25 degree C. When extensive branching has taken place, some fraction of the polymer is usually branched beyond the gel point and swells but does not dissolve in the solvent. The quantity of the gel fraction is taken to indicate the relative amount of long chain branching. To measure the quantity of gel, about 2 grams of polymer was placed in a jar containing about 250 ml of n-hexane and allowed to stand for two weeks at ambient temperature with occasional gentle swirling during that period. Undissolved polymer was recovered by decanting the jar contents into a tared 350 mesh stainless steel screen which was then placed in a vacuum oven held at 60 degrees C. After 12 hours of drying to evaporate the solvent the screen was reweighed to determine the amount of undissolved polymer. rne ratio of the weight of undissolved polymer to original polymer charge is the fraction of gel. In the following examples polynerization was started with no or low feed of silicate compound to the reactor. After providing sufficient time to achieve steady state, a polymer sample was collected for analysis and the polymerization rate measured. The flow rate of silicate was then initiated or increased, and the reactor again allowed to reach steady state. A second polymer sample was obtained for analysis. This procedure was followed for several different levels of silicate feed rate. All other polymerization conditions were held constant for an experiment. The polymerization data is shown in Table I. EXAMPLE 1 A control polymerization using the conditions shown in Table I was carried out using VOC13/ethyl aluminum sesquichloride (EASC) as the catalyst system. No silicate was added. The polymer contained 19Z gel. Because of the large amount of insoluble fraction, molecular weight distribution could not be measured accurately by GPC analysis. Polymerization data are shown in Table II. EXAMPLE 2 Example 1 was repeated but ethyl silicate (Si(OEt)4) was added to the reactor. As seen from Table II the Mooney viscosity of the polymer dropped as the silicate feed rate was increased. At Si/V ratio of 0.75, gel content was 5Z as compared to 19X for the control. Catalyst efficiency and propylene conversion are slightly reduced relative to the control. Raising the Si/V ratio from 0.75 to 1.0 has a deleterious effect on catalyst activity without significantly reducing branching further. EXAMPLE 3 Example 1 was repeated except that methyl silicate (Si(OMe)4) was added to the reactor. As the silicate level was increased the polymer molecular weight dropped and the MWD breadth narrowed, as shown by the Mw/Mn ratio, indicating that branching was being eliminated. At an Si/V ratio of 1.0 the amount of gel was reduced to 3Z without significant loss in catalyst activity relative to the control of Example 1. See Table II. EXAMPLE 4 A control experiment using the conditions shown in Stable III was run carrying out the polymerization using VCl4/ethyl aluminum sesquichloride as the catalyst system in the absence of silicate. The gel content of the polymer was 46Z and the Mooney was quite high (Ca 100). The results are shown in Table II. EXAMPLES 5 - 8 Example 4 was repeated varying the quantity and type of silicate used as the chain branching suppressor. In all cases at ratios of 0.5 to 1 mole Si/mole V gave polymers of narrow MWD with gel content of less than 2 wt Z. As shown in Table II at these silicate levels the detrimental effect on catalyst activity was minimal. EXAMPLE 9 The procedure of Example 1 was repeated with ethyl aluminum dichloride as cocatalyst and VOCl3 as the catalyst. Reactor temperature was 30 C and residence time was 13 minutes. Feed rates were as follows: ethylene = 2.53g/lOOg hexane propylene = 12.OgllOOg hexane VOC13 = .0067g1100g hexane In the initial run, at an A1/V ratio of 10 and an NB feed of O.lSg/lOOg hexane, a polymer containing about 4 wt' ENB was produced. However, severe gellation occurred in the reactor leading to an extremely viscous polymer solution. Reactor operation was unsteady and no polymerization data could be obtained. S4B feed rate was halved, giving an improvement in reactor operability and producing a polymer with 2.3 wtZ ENB. This polymer contained 28I gel (see Table II). Si(OEt)4 was then fed to the reactor and the A1/V ratio was reduced to 6. As shown in Table II, , the addition of Si(OEt)4 lowered polymer Mooney viscosity, narrowed MWD, and at a Si/V ratio of 0.5 mol/mol reduced the gel content to 4.7X. Surprisingly, the use of Si(OEt)4 also led to improved catalyst efficiency and propylene conversion. EXAMPLE 10 A comparison experiment was run to demonstrate the effectiveness of silicates as branching suppressors as compared with the prior art branching suppressor, ammonia, a Lewis base. The polymerization was carried out with VOC13/ethyl aluminum sesquichloride (EASC) catalyst system using ammonia in one instance (Case A) and Si(OEt)4 in the other (Case B). The details of the polymerization and polymer characterization are shown in Table IV. The experiments were run identically except that in Case B the propylene feed was decreased to compensate for the higher reactivity of propylene when Si(OEt)4 is used as the branching suppressor. Also, the A1/V ratio was reduced from 6 to 5 with the addition of Si(OEt),. The polymers produced were essentially identical but the use of Si(OEt)4 instead of NH3 resulted in a 20% irprovement in propylene conversion. EXAMPLE 11 That the silicates of this invention have only a minor effect on polym.erization catalyst efficiency or activity was demonstrated by carrying out an ethylenepropylene copolymerization in the absence of ENB with increasing levels of Si(OEt)4. As shown in Table V, incremental additions of silicate up to 0.5 Si/V do not significantly disturb any of the catalyst activity or propylene conversion. TABLE I CONDITIONS FOR POLYMERIZATION VOCl3 - Et3Al2Cl3 TEMPERATURE 32( C) RESIDENCE TIME 13 mien. AL/V MOLAR RATIO 5 PRESSURE 500kpa REACTOR FEEDS ETHYLENE 2.53g/lOOg hexane PROPYLENE 12.0g/100g hexane ENB 0.29g/100g hexane HYDROGEN 60 wppm on ethylene VOCL3 .O075g/100g hexane HEXANE 2.66 kg/hour AMMONIA See Text TEOS TABLE II Cat.ê Prop. Polymer Mooney4 Example Catalyst CoCat SilicateÚ Al/V Si/V Eff. Conv. Composition, wt% Visc. Col Mg/Mn mol/mol mol/mol % Ethylene ENB (%) 1 VOCL3 EASC None 5 0 652 23 49 5.1 91 19 -2 VOCL3 EASC Si(OEt)4 5 .25 595 21 44 5.2 81 10 2.33 .75 561 20 20 46 5.1 48 5.0 2.39 1.0 473 14 51 5.5 43 4.9 3 VOCl3 EASC Si(OMe)4 5 .25 620 22 44 5.4 78 8.8 .50 600 21 44 5.3 58 28.8 6.2 1.0 625 22 44 5.2 37 3.0 1.5 489 14 53 5.5 30 1.0 1.86 2.0 357 9 61 5.9 23 3.3 4 VCl4 EASC None 5 0 928 21 45 4.4 100 46.0 -5 VCl4 EASC Si(OEt)4 5 .16 932 21 44 5.0 61 17.0 4.77 .50 938 22 43 5.7 60 0 2.52 .75 942 22 43 5.1 58 0 1.5 896 21 43 5.2 50 .5 6 VCl4 EASC Si(OMe)4 5 .25 892 21 45 6.0 69 6.8 .37 910 21 44 5.0 61 3.1 .50 920 22 44 5.2 61 1.0 944 22 47 5.5 58 .80 1.5 896 20 43 5.2 55 .42 1.85 7 VCl4 EASC PhSi(OEt)3 5 .16 952 22 43 4.4 51 .25 942 22 44 62 .50 914 21 41 55 2.7 3.9 TABLE II (continued) Cat.ê Prop. Polymer Mooney4 Example Catalyst CoCat SilicateÚ Al/V Sl/V trf. Conv. Composition. wt% Visc. Cel Hw/Mn mol/mol mol/mol % Ethylene ENB (%) 8 VCl4 EASC ClSi(OEt)3 5 .16 842 19 45 5.5 90 9.6 1.9 .50 808 18 45 5.3 87 2.4 1.9 .75 876 20 43 5.1 71 1.7 2.0 1.5 830 19 44 5.5 59 0 9 VOCl3 EADC None 10 0 536 15 49 2.3 113 28 7.5 Si(OEt)4 6 .25 610 17 48 1.6 81 Si(OEt)4 6 .50 630 18 47 1.7 65 4.7 2.7 (1) Si(OEt)4 = ethyl silicate Si(OMe)4 = methyl silicate PhSi(OEt)3 = triethoxy phenyl silane CiSi(OEt)3 = triethoxy chloro silane (2) Cat. Eff. = Catalyst efficiency, wt. polymer produced/wt. catalyst fed. (3) Prop. Conv. = Propylene conversion, (wt. propylene reacted/wt. propylene fed) x 100%. (4) Mooney viscosity conditions = small rotor (MS) at 127 C. TABLE III CONDITIONS FOR POLYMERIZATION: VCl4-EASC TEMPERATURE 32( C) RESIDENCE TIME 13 min. Al/V MOLAR RATIO 5 PRESSURE SOOkpa REACTOR FEEDS ETHYLENE 2.53g/100g hexane PROPYLENE 12.0g/100g hexane ENB 0.29g/100g hexane VCl4 .005g/100g hexane HEXANE 2.66 kg/hr. HYDROGEN 60 wppm on Ethylene AMMONIA) See Text TEOS } Table IV A B Temperature, degrees C 35 35 Residence Time (min) 10.1 10.1 Feeds (g/100 g of hexane) Catalyst: VOCl3 .0085 .0085 Cocatalyst: EASC (Al/Vmolar ratio) 6 5 Ethylene 3.56 3.56 Propylene 8.00 6.50 5-Ethylidene-2-Norbcrnene (ENB) 0.259 0.259 Ammonia (N/V molar ratio) 2.0 0.0 Si(OEt)4 (Si/V molar ratio) 0.0 0.6 H2 (g/106g of ethylene) 90 90 Polymer Characterization ML 127 (1+8)Ú 56 53 Ethylene Content (wtZ) 52.8 52.3 ENB Content (wtZ) 4.25 4.25 Process Details C2 = Conversion (Z) 85 80 C3 = Conversion (Z) 30 36 Catalyst Efficiency (g polymer 670 640 g of VC14) 1 Mooney viscosity conditions (ML) - large rotor at 127 degrees C. TABLE V EFFECT OF TEOS CN VCl4-EASC SYSTEM (COPOLYMER) Run &num; Si/V C2 Wt% Ms127Ú CEê C3 Conv. . 1 0.0 40 49 1020 26 2 0.16 40 59 1040 26 3 0.25 40 48 1020 25 4 0.50 40 63 1000 25 Mooney viscosity conditions - small rotor (Ms) at 1270C. 2 Catalyst efficiency - wt. of polymer produced/wt. of catalyst fed. 3 C3 conv. - Fropylene conversion: (wt. of propylene reacted/wt. of propylene fed) x 100%. For a better understanding of the invention, a summary is provided hereinafter in which preferred aspects of the invention are listed numerically; the numerical order of these aspects is not intended to be significant. Aspects of the Invention: 1. In a solution polymerization process for the preparation of an EPDM using as a catalyst a hydrocarbon soluble vanadium compound in conjunction with an aluminum compound cocatalyst the improvement which comprises utilizing as a chain branching suppressor a silicate compound of the general formula Si(OR)XLy wherein x is an integer of 3 to 4, L is halogen, hydrogen, or R; y is 4-x, and R is a hydrocarbyl moiety. 2. The process according to aspect 1 wherein the vanadium compound has a vanadium valence of at least 3. 3. The process according to aspect 1 wherein R is an alkyl, cycloalkyl or aromatic moiety. 4. The process according to aspect 3 wherein R is methyl, ethyl or phenyl. 5. The process according to tE 1 wherein x is 4. 6. The process according to aspect 1 wherein x is 3 and L is chlorine. 7. The process according to aspect 1 wherein the silicate compound is tetramethoxysilane or tetra e thoxysilane. 8. The process according to aspect 1 wherein the silicate and vanadium compounds are utilized at an Si/V mole ratio of about 0.1 to about 3.0. 9. The process according to aspect; 8 wherein Si/V is about 0.3 to about 2.0. 10. The process according to aspect 9 wherein Si/V is about 3.6 to about 1.5. 11. The process according to aspect 1 wherein the vanadium compound is VX4 or VOXn(OR')3.n wherein X is halogen, R' is a hydrocarbyl moiety and n is 2 or 3. 12. The process according to aspect 11 wherein X is chlorine or bromine. 13. The process according to aspect 11 wherein X is chlorine. 14. The process according to aspect 11 wherein R' is C1-C10 alkyl or cycloalkyl, phenyl or benzyl. 15. The process according to aspect 14 wherein R' is C1-C4 alkyl. 16. The process according to aspect 1 wherein the aluminum compound is an alkyl aluminum sesquihalide or a compound of the formula AlR' 'bX'3.b wherein X' is halogen, R'' is a hydrocarbyl moiety and "b" is 1 to 2. 17. The process according to aspect 16 wherein R'' is C1-C4 alkyl or phenyl. 18. The process according to aspect 16 wherein X' is chlorine or bromine. 19. The process according to aspect 17 wherein X' is chlorine. 20. The process according to aspect 16 wherein the sesquihalide is methylalumint:rn sesquichloride, ethylaluminun sesquichloride, or lsobutylaluminum sesquichloride. 21. The process according to aspect 11 wherein the vanadium compound is VOCl3, the aluminum compound is ethyl aluminum sesquichloride, the silicate is tetraethoxysilane and the mole ratio of silicate to vanadium compound based on silicon and vanadium (Si/V) is about 0.6 to about 1.5. 22. The process according to aspect 12 wherein the mole ratio Si/V is about 0.4 to about 1.0. 23. The process according to aspect 11 wherein the aluminum compound is ethyl aluminum sesquichloride (EASC), ethyl aluminum dichloride, or diethylaluminum chloride. 24. The process according to aepect 23 wherein the vanadium compound is VC14 and the aluminum compound is EASC. 25. The process according to aspect 24 wherein the silicate compound is tetraethoxysilane and the silicate and vanadium compounds are utilized at an Si/V mole ratio of 0.1 to about 3.0. 26. The process according to aspect 25 wherein the Si/V mole ratio is about 0.3 to about 2.0. 27. The process according to aspect 24 wherein the silicate compound is tetramethoxysilane and the silicate and vanadium are utilized at an Si/V mole ratio of about 0.1 to about 3.0. 28. The process according to aspect 27 wherein the Si/V oole ratio is about 0.3 to about 2.0. 29. The process according to aspect 1 wherein the EPDM comprises ethylene, propylene and a termonomer wherein the termonomer is ENB or 1,4-hexadiene, dicyclopentadiene or methylene norbornene. 30. The process according to aspect 1 wherein hydrogen is used as a molecular weight modifier, 31. The process according to a < wct 4 4 wherein the silicate compound is phenyltriethoxysilane or chlorotriethoxysilane. 32. A catalyst system for the preparation of an EPDM in a diluent for the polymerization process which comprises a vanadium compound catalyst, an aluminum compound cocatalyst and a silicate compound chain branching suppressor wherein the vanadium compound is soluble ir. the diluent and the vanadium valence is at least 3; the aluminum compound is of the formula Al2R"3X'3 or A1R"bX'3-b wherein X' is halogen, b is 1 to 2, and R" is a hydrocarbyl moiety and the silicate compound has the general formula Si(OR)xLy wherein x is an integer of 3 to 4, L is halogen, hydrogen or R; y = 4-x and R is a hydrocarbyl moiety. 33. The catalyst system according to aspect 32 wherein i'' of the aluminum compound is a C1-C20 alkyl, cycloalkyl or aromatic moiety. 34. The catalyst system according to aspect 33 wherein R" is methyl, ethyl, n-propyl, iso-butyl, cyclohexyl or phenyl. 35. The catalyst system according to aspect 32 wherein the vanadium compound is VX4 or VOX, (OR') wherein X is halogen and R is a hydrocarbyl moiety. 36. The catalyst system according to aspect 35 wherein X and X' are each independently selected from the group consisting of chlorine, bromine or iodine. 37. The catalyst system according to aspect 35 wherein X is chlorine or bromine. 38. The catalyst system according to aspect 35 wherein X is chlorine. 39. The catalyst system according to aspect 35 wherein R' is C1-C10 alkyl, cycloalkyl, phenyl or benzyl. 40. The catalyst system according to aseect 39 wherein R' is C1-C4 alkyl. 41. The catalyst system according to aspect 32 wherein the aluminum compound of the formula Al2R''3R'3 is an alkyl aluminum sesquihalide. 42. The catalyst systen according to aspect 41 wherein the sesquihalide is methyl aluminum sesquichloride or ethyl aluminum sesquichloride. 43. The catalyst system according to aspect 32 wherein X' is chlorine or bromine. 44. The catalyst system according to aspect 32 wherein the aluminum compound is AlR''bX'3 b wherein l'' is C1-C10 alkyl or cycloalkyl, phenyl or benzyl and X' is chlorine or bromine. 45. The catalyst system according to aspect 44 wherein R'' is C1-C6 alkyl. 46. The catalyst system according to aspect 32 wherein the aluminum compound is ethyl aluminum sesqui. chloride, diethyl aluminum chloride or ethyl aluminum dichloride. 47. The catalyst system according to aspect. 46 wherein the aluminum compound is ethyl aluminum sesqui chloride, diethyl aluminum chloride or ethyl aluminum dichloride and the vanadium compound is VOCI3 or VC14. 48. The catalyst system according to aspect 32 wherein the mole ratio of aluminum to vanadium (Al/V) is about 1 to abaut4O. 49. The catalyst system according to aspect 48 wherein A1/V is about 2 to about 20. 50. The catalyst system according to aspect 49 wherein Al/V is about 3 to about 10. 51. The catalyst system according to aspect 32 wherein R of the silicate compound is an alkyl, cycloalkyl or aromatic moiety and L is chlorine, bromine or iodine. 52. The catalyst system according to aspect 51 wherein L is chlorine. 53. The catalyst system according to aspect 51 wherein P. is methyl, ethyl, n-propyl, n-butyl, cyclohexyl or phenyl. 54. The catalyst system according to aspect 32 wherein the silicate compound is tetramethoxysilane, tetraethoxysilane, phenyltriethoxysilane or chlorotriethoxysilane. 55. The catalyst system according to aspect 31 wherein the silicate is utilized at a mole ratio of silicon to vanadium (Si/V) of about 0.1 to about 3.0. 56. The catalyst system according to zipped 55 wherein Si/V is about 0.3 to about 2.0. 57. The catalyst system according to aspect 56 wherein Si/V is about 0.6 to about 1.5. 58. The catalyst system according to aspect 55 wherein the vanadium compound is VC14 or VOCl3, the aluminum compound is alkylaluminum sesquichloride, dialkylaluminum chloride or alkylaluminum dichloride, and S/V is about 0.6 to about 1.5. 59. The catalyst system according to aspect 58 wherein Si/V is about 0.4 to about 1.0. 60. The catalyst system according to aspect 55 wherein the vanadium compound is VC1,, the aluminum compound is ethyl 1 aluminum sesquichloride, the silicate compound is tetramethyoxysilane. 61. The catalyst system according to aspects 60 wherein Si/V is about 0.3 to about 2.0. 62. The catalyst system according to aspect 55 wherein the vanadium compound is VCl4. the aluminum compound is ethyl aluminum sesquichloride and the silicate compound is phenyltrie.thoxysilane or chlortriethoxysilane. 63. The catalyst system according to aspect 62 wherein Si/V is about 0.3 to about 2.0. 64. The catalyst system according to aspect 55 wherein the vanadium compound is VOCl3, the aluminum compound is ethyl aluminum sesquihalide, the silicate compound is tetraethoxysilane or tetramethoxysilane and Si/V is about 0.3 to about 2.0. 65. The catalyst system according to aspect 55 wherein the vanadium compound is VCL4. 66. The catalyst system according to aspect. 55 wherein the vanadium compound is VOCl3. 67. The catalyst system according to aspect 66 wherein .the aluminium compound is ethyl aluminum dichloride, the silicate compound is tetramethoxy silane and the Si/V ratio is about 0.3 to about 2.0. 68. The catalyst system according to aspect 67 wherein the Si/V ratio is about 0.4 to about 1.0. 69. The catalyst system according to aspect 67 wherein the aluminum compound is ethylaluminum dichloride, the silicate compound is tetramethoxy silane and the Si/V ratio is about 0.3 to about 2.0. 70. The catalyst system according to aspect 69 where the Si/V ratio is about 0.4 to about 1.0. 71. The process according to aspect 17 wherein R'' is methyl, ethyl, n-propyl, iso-butyl, hexyl or cyclohexyl. 72. The catalyst system according to aspect. 44 wherein R'' is methyl, ethyl, n-propyl, iso-butyl, hexyl or cyclohexyl.

Claims: CLAIMS: 1. A solution polymerization process for the preparation of an EPDM using a hydrocarbon soluble vanadium compound as catalyst in conjunction with an aluminum compound cocatalyst and a chain branching suppressor characterised in that the chain branching suppressor comprises a silicate compound of the general formula Si(OR)xLy wherein x is 3 or 4, L is halogen, hydrogen, or R; y is 4-x, and R is a hydrocarbyl moiety. 2. The process according to claim 1 wherein R is an alkyl, cycloalkyl or aromatic moiety. 3. The process according to claim 2 wherein R is methyl, ethyl or phenyl. 4. The process according to claim 1, 2 or 3 wherein x is 3 and L is chlorine. 5. The process according to claim 1,2,3 or 4 wherein the silicate compound is tetramethoxysilane, tetraethoxysilane, phenyltriethoxysilane or chlorotriethoxysilane. 6. The process according to any one of the preceding claims wherein the vanadium compound has a vanadium valence of at least 3. 7. The process according to any one of the preceding claims wherein the silicate and vanadium compounds are utilised at an Si/V mole ratio of 0.1 to 3.0. 8. The process according to any one of the preceding claims wherein the vanadium compound is VX4 or VOXnfOR')3-n wherein X is halogen, R' is a hydrocarbyl moiety and n is 2 or 3. 9. The process according to claim 8 wherein X is chlorine or bromine. 10. The process according to claim 8 or 9 wherein R' is C1-C10 alkyl or cycloalkyl, phenyl or benzyl. 11. The process according to any one of the preceding claims wherein the aluminum compound is an alkyl aluminum sesquihalide or a compound of the formula AlR''bX'3¯ wherein X' is halogen, R'' is a hydrocarbyl moiety and b is 1 or 2. 12. The process according to claim 11 wherein R' t is C1-C4 alkyl, hexyl, cyclohexyl or phenyl, or wherein the alkyl group of the alkyl aluminum sesquihalide is methyl, ethyl or isobutyl. 13. The process according to claim 11 or 12 wherein X' is chlorine or bromine. 14. The process according to claim 8 wherein the vanadium compound is VOC13, the aluminum compound is ethyl aluminum sesquichloride, the silicate is tetraethoxysilane and the mole ratio of silicate to vanadium compound based on silicon and vanadium (Si/V) is from 0.6 to 1.5. 15. The process according to claim 8 wherein the vanadium compound is VC14 and the aluminum compound is ethylaluminum sesquichloride. 16. The process according to claim 15 wherein the silicate compound is tetramethoxysilane or tetraethoxysilane and the silicate and vanadium compounds are utilised at an Si/V mole ratio of from 0.1 to 3.0. 17. The process according to any one of the preceding claims wherein the EPDM comprises ethylene, propylene and a termonomer wherein the termonomer is ENB or 1,4-hexadiene, dicyclopentadiene or methylene norbornene. 18. The process according to any one of the preceding claims further characterised in that hydrogen is used as a molecular weight modifier. 19. A catalyst system for the preparation of an EPDM in a diluent for the polymerization process which comprises a vanadium compound catalyst, an aluminum compound cocatalyst and a silicate compound chain branching suppressor wherein the vanadium compound is soluble in the diluent and the vanadium valence is at least 3; the aluminum compound is of the formula A12R''3X'3 or AlR"bX'3¯b wherein X' is halogen, b is 1 or 2, and R" is a hydrocarbyl moiety and the silicate compound has the general formula: Si(OR)XLy wherein x is an integer of 3 to 4, L is halogen, hydrogen or R; y = 4-x and R is a hydrocarbyl moiety. 20. The catalyst system according to claim 19 wherein R" is a C1-C20 alkyl, cycloalkyl or aromatic moiety, preferably methyl, ethyl, n-propyl, iso-butyl, hexyl, cyclohexyl or phenyl. 21. The catalyst system according to claim 19 or 20 wherein the vanadium compound is VX4 or VOXn(OR')3-n wherein X is halogen and R is a hydrocarbyl moiety, preferably VOC13 or VC14. 22. The catalyst system according to claim 19, 20 or 21 wherein X and X' is independently chlorine, bromine or iodine. 23. The catalyst system according to claim 21 or 22 wherein R' is Cl-Clo alkyl, cycloalkyl, phenyl or benzyl. 24. The catalyst system according to any one of claims 19-23 wherein the aluminum compound of the formula A12R"3X'3 is an alkyl aluminum sesquihalide, preferably methyl aluminum sesquichloride or ethyl aluminum sesquichloride, or the aluminum compound is diethylaluminum chloride or ethylaluminum dichloride. 25. The catalyst system according to any of claims 19-24 wherein the mole ratio of aluminum to vanadium (A1/V) is from 1 to 40. 26. The catalyst system according to any of claims 19-25 wherein R of the silicate compound is an alkyl, cycloalkyl or aromatic moiety preferably methyl, ethyl, n-propyl, n-butyl, cyclohexyl or phenyl, and L is chlorine. 27. The catalyst system according to claim 26 wherein the silicate compound is tetramethoxysilane, tetraethoxysilane, phenyltriethoxysilane or chlorotriethoxysilane. 28. The catalyst system according to any of claims 19-27 wherein the silicate is utilised at a mole ratio of silicon to vanadium (Si/V) of from 0.1 to 3.0. 29. The catalyst system according to any one of claims 19-28 wherein the vanadium compound is VC14 or VOC13, the aluminum compound is alkylaluminum sesquichloride, dialkylaluminum chloride or alkylaluminum dichloride, and Si/V is from 0.6 to 1.5. 30. The catalyst system according to any one of claims 19-28 wherein the vanadium compound is VC14 or VOC13, the aluminum compound is ethyl aluminum sesquichloride, and the silicate compound is tetraethoxysilane, tetramethoxysilane, phenyltriethoxysilane or chlorotriethoxysilane. 31. The use of a silicate compound of formula Si(OR)xLy (wherein x = 3 or 4, L is halogen, hydrogen or R, y = 4 - x and R is a hydrocarbyl moiety) as a chain branching suppressor in polymerization reactions for producing EPDM which employ a vanadium compound catalyst and an aluminum compound co catalyst.

Inventors: COZEWITH, CHARLES, DATTA, SUDHIN
Applicants: EXXON CHEMICAL PATENTS INC.
Application year: 1986
Main classification: C08F210
IPC codes: C08F210, C08F4, C08F2