POLYMER-SUPPORTED CATALYST FOR OLEFIN POLYMERIZATION

Abstract: The present invention is directed to a novel supported Ziegler-Natta catalyst useful for the polymerization of alpha -olefins. More specifically, the supported Ziegler-Natta catalyst of the present invention comprises a particulate functionalized copolymeric support, an organometallic compound and a transition metal compound. A novel method of preparing the particulate functionalized copolymeric supports of the instant invention is also provided.

Description: - 1 - POLYMER-SUPPORTED CATALYST FOR OLEFIN POLYMERIZATION The present invention relates to a novel supported Ziegler-Natta catalyst and catalyst system 5 useful for polymerizing or copolymerizing α-olefins. More specifically, the supported Ziegler-Natta catalyst of the present invention comprises an organometallic component; a transition metal component; and a particulate functionalized copolymeric support material. ° The instant invention also relates to a method of preparing a microfine particulate functionalized copolyiTieric support material as well as to a process for (co)polymerizing α-olefins using the supported Ziegler- Natta catalyst of the present invention. -^ Ziegler-type catalysts, which usually include components of a metal of Group IV-VIB and organometallic compounds of Groups I-IIIA of the Periodic Table of Elements, are widely utilized in the polymerization of olefins. These catalysts are known to effectively promote the high yield polymerization of olefins possessing the desired characteristics of these polymers. However, the use of conventional Ziegler-type catalysts are subjected to important failings. Thus, new and improved catalysts are continually being sought 2 5 and developed. One such improvement comprises supporting the above-identified Ziegler-type catalyst components on refractory inorganic oxide supports, such as Si0 2 , l-O j and MgO. These supports are available in variety of 30 particle sizes and porosities. 35 Moreover, it is well documented in the art that Ziegler-type catalysts supported on inorganic oxides exhibit high catalytic activity and enhanced polymeric properties compared to Ziegler-Natta catalyst that are unsupported. An example of a catalyst which employs silica as a support material is described in U.S. Patent No. 4,950,631 to Buehler et al . Increased activity of such silica supported catalysts can be achieved by adding one or more cocatalyst components or promoters to the solid catalyst component. Despite their usefulness, inorganic oxide supports have several deficiencies. For example, inorganic oxide supports must be calcined at high temperatures or chemically treated with appropriate reagents to remove physically adsorbed water from the surface of the support. The presence of water on the surface of inorganic oxide supports is well known in the art as being a catalytic poison which can adversely affect the catalytic activity of the catalyst. In addition, inorganic oxide supports have a limited maximum pore size which also can restrict the catalytic performance of the catalyst. Although large pore size inorganic oxides are available, these materials may be friable and the use thereof as catalyst supports may, through attrition, lead to the formation of unwanted fine particles. Furthermore, it is well known in the art that inorganic oxides not only adsorb water but other commonly occurring catalyst poisons, such as oxygen. Thus, great care in handling and preparing inorganic oxide supported catalysts must always be exercised. To overcome the above deficiencies that are commonly observed in inorganic oxide supported catalysts, many research groups have focused on substituting polymeric supports for inorganic oxide supports. See, for example, U.S. Patent Nos. 4,098,979; 4,268,418; 4,404,343; 4,407,722; 4,568,730; 4,900,706; 5,051,484; 5,118,992; and 5,275,993. Typically, polymeric supports employed in the prior art are organic polymers such as polyethylene, polypropylene, polystyrene, polyvinyl alcohol, poly(styrene-divinylbenzene) , poly(methylmethacrylate) and the like. The use of these polymeric supports provides several advantages over similar olefin polymerization catalyst components supported upon inorganic oxides. For example, polymeric supports usually require no dehydration prior to the use thereof; they can be easily functionalized which afford more opportunities to prepare tailored made catalysts; they are inert; they can be prepared with a wide range of physical properties, via chemical and mechanical means to intentionally give porosity, morphology and size control to the catalyst; and they offer a cost advantage over inorganic oxide supports. Despite the advantages listed hereinabove, prior art polymeric supports still possess certain inherent disadvantages which decrease their acceptability as viable replacements for inorganic supports. For instance, polymeric supports often lack structural stability at high temperatures and under some solvent conditions. Moreover, the porosity and size of the polymeric support, due to swelling may change drastically over the short time duration required to prepare the catalyst. Furthermore, the choice of the polymer support must be compatible with the polymer produced in order to insure that this incompatibility does not contribute to the formation of gels. It would thus be highly advantageous to provide a polymeric support which overcomes the above drawbacks while still being useful in the polymerization o ÷f α_-ol.e*fι • ns. » The present invention is directed to a novel Ziegler-Natta catalyst that is useful in the homopolymerization or copolymerization of α-olefins which comprises a particulate functionalized polymeric support, at least one organometallic compound and at least one transition metal compound. The particulate functionalized polymeric support of the present invention includes copolymers of an α-olefin and a monomer which may be a vinyl ester or an acrylate, the latter being used in a generic sense to include esters of acrylic as well as methacrylic acid. The novel Ziegler-Natta catalysts of the present invention, in combination with suitable cocatalysts, provide an a- olefin polymerization catalyst system which produces polymers comprised predominantly of ethylene and/or propylene with densities ranging from about 0.90 to about 0.97 and having a desirable balance of rheological and physical properties making them useful in a wide range of applications. In accordance with a preferred embodiment of the present invention, the particulate functionalized copolymeric support is a microfine powder comprised of particles that are spherical or substantially spherical. The term "microfine" means that the particles of the support material have a median particle size of from about 1 to about 500 microns. The microfine powders which are employed in the present invention are prepared by heating a copolymer to a temperature above the melting point of the copolymer in the presence of a nonionic surfactant; dispersing the mixture produced in the heating step in a dispersant to produce droplets of a desired size; and cooling the dispersion to a temperature below the melting point of the copolymer. In another aspect of the present invention, a process for polymerizing one or more α-olefins is provided. In this process at least one α-olefin is polymerized under olefin polymerization conditions utilizing the catalyst system of the present invention which includes the particulate functionalized copolymer suppoit, organometallic compound(s) and transition metal compound(s) as the solid catalyst component, along with a suitable cocatalyst component (s) . The particulate functionalized supports of the instant invention are copolymers of an α-olefin and a vinyl ester or an acrylate. The term "acrylate" being used in the generic sense to encompass esters of both acrylic and methacrylic acid. The copolymers from which the particulate functionalized supports of the present invention are obtained are produced by copolymerizing an α-olefin, especially ethylene and/or propylene, with one or more monomers selected from the group consisting of vinyl esters, lower alkyl acrylates, arylacrylates and methacrylate monomers . Copolymerizations of α-olefins and the above monomers are well known and are generally carried out at pressures of up to about 30,000 psi and temperatures of from about 150°C to about 250°C in the presence of suitable catalysts. A typical process for copolymerizing ethylene and lower alkyl acrylates is described in U.S. Patent No. 2,200,429 while a typical process for copolymerizing ethylene and vinyl acetate is described in British Patent Specification 1443394. The above-mentioned copolymers have an α- olefin as the major constituent. More preferably, the copolymers of the invention have from about 50.1 to about 99.9 weight percent C 2 . 3 α-olefin copolymenzed with from about 0.1 to about 49.9 weight percent of the monomer. Preferably, the copolymers will contain from about 70 to about 99 weight percent ethylene, propylene or mixtures thereof and from about 1 to about 30 weight percent of one of the above-identified monomers. In one highly useful embodiment, the copolymer supports comprise from about 80 to about 95 weight percent ethylene and about 5 to about 20 weight percent acrylate or vinyl ester monomer. The vinyl esters employed in the present invention may be a vinyl ester of a C 2 -C 6 aliphatic carboxylic acid, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pentanoate or vinyl hexanoate. Of these vinyl esters, vinyl acetate is particularly preferred. The acrylate monomer utilized in the present invention has the formula O II CH 2 = CRCOR 1 where R is hydrogen or methyl and R 1 is an alkyl group having from about 1 to about 12 carbon atoms or an aryl group having from about 6 to about 12 carbon atoms . Alkyl groups may be straight chain or branched and can be saturated or unsaturated. Aryl groups can be unsubstituted, e.g., phenyl, or can contain one or more hydrocarbyl substituents, e.g., benzyl, tolyl, xylyl . Representative acrylate comonomers which can be used for the copolymer include: methyl acrylate, ethyl acrylate, isopropyl acrylate, allyl acrylate, n- butyl acrylate, t-butyl acrylate, neopentyl acrylate, n- hexyl acrylate, cyclohexyl acrylate, benzyl acrylate, phenyl acrylate, tolyl acrylate, xylyl acrylate, 2- ethylhexyl acrylate, 2-phenylethyl acrylate, n-decyl acrylate, isobornyl acrylate, n-octadecyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isodecyl methacrylate, lauryl methacrylate and the like. Among the preferred acrylate comonomers, alkyl acrylate comonomers having the above structural formula where R is hydrogen and R 1 is a C,. 4 alkyl group are particularly useful. Of these, methyl acrylate, ethyl acrylate and n-butyl acrylate are especially preferred. In a highly useful embodiment of the invention, the particulate supports are ethylene-methyl acrylate, ethylene-ethyl acrylate, ethylene-vinyl acetate and ethylene-n-butyl acrylate copolymers. The melt index of the copolymers can range from about 0.1 up to about 400 g/10 min. or above. However, in a preferred embodiment where the supports are microfine powders comprised of particles which are spheroidal or substantially spheroidal, the melt index is in the range of from about 1 up to about 125, and more preferably, from about 1 up to about 60. All melt indexes referred to herein are determined at 190°C in accordance with ASTM D 1238, condition E, and are expressed in grams per 10 minutes. The copolymers used to form the supported Ziegler-Natta catalysts of the invention are particulate products comprised of discrete particles whose median particle size can range from about 1 up to about 1500 microns, and more preferably, from about 1 to about 1000 microns . The copolymer powders can be obtained by spray drying or the copolymer can be precipitated from solution by the addition of a suitable precipitating agent, e.g., methanol. The particulate supports obtained by spray drying the copolymer or copolymers may also be ground or milled to produce powders within the acceptable size range. Mechanical grinding may be carried out under ambient conditions if the copolymer has a sufficiently high melting point and does not degrade under the grinding conditions; however, it is more customary to cryogenically grind the copolymers. After grinding, the powders can be sieved to recover particles of the desired size and particle size distribution. Suitable particulate supports can also be produced using conventional solution and dispersion processes. In a particularly useful embodiment of the invention, the supports are "microfine" powders of functionalized copolymers obtained by dispersion processes. Particles produced by these processes are spheroidal or substantially spheroidal in shape. Microfine powders produced using dispersion processes, in addition to having spheroidal particles, also have substantially narrower particle size distributions than reactor powders or powders produced by precipitation, grinding or milling. Preferred microfine functionalized polymer supports are comprised of discrete particles which are spheroidal or substantially spheroidal in shape and have a median particle size (diameter) from about 1 microns to about 500 microns. More preferably, the median particle size is from about 5 microns to about 300 microns and in an especially useful embodiment, the median particle size is from about 20 to about 200 microns. Median diameters as used herein are obtained from the particle volume distribution curve. The copolymers of the present invention are converted to microfine powders using the dispersion technique of U.S. Pate'nt Nos. 3,422,049, 3,432,483 and 3,746,681, details of which are incorporated herein by reference. In the powder-forming operation, the copolymer is charged to the reactor with a polar liquid medium and nonionic surfactant and a dispersion is formed in accordance with conventional dispersing procedures described in the art. The dispersing apparatus may be any device capable of delivering sufficient shearing action to the mixture at elevated temperature and pressure. Conventional propeller stirrers designed to impart high shear can be used for this purpose. The vessel may also be equipped with baffles to assist in dispersing the copolymer. Particle size and particle size distribution will vary depending on the shearing action which, in turn, is related to the stirrer design and rate of stirring. Agitation rates can vary over wide limits but the speed of the stirrer will usually be controlled so that the tip speed is between about 400 and about 4000 ft/min and, more commonly, about 800 and about 3500 ft/min. Higher tip speeds are generally used for batch operation, usually about 2500-3500 ft/min. Tip speeds for continuous procedures most generally range between about 800 and about 3000 ft/min. The dispersion process is typically carried out in a vessel which enables the powder-forming process to be conducted at elevated temperature and pressure. In the usual batch process, all of the ingredients are charged to the vessel and the mixture is heated to a temperature above the melt point of the copolymer. While the temperature will vary depending on the specific polymer being used, it will typically range from about 175°C to about 250°C. Since the fluidity of polymers is temperature related, it may be desirable to carry out the process at temperatures substantially above the melt point of the copolymer to facilitate formation of the dispersion; however, the temperature should not exceed the thermal degradation temperature of the polymer. Stirring is commenced after the desired temperature is reached and continued until a dispersion of the desired droplet size is produced. This will vary depending on the particular copolymer being used, temperature, amount and type of surfactant, and other process variables, but generally will range from about 5 minutes to about 2 hours. Stirring is most commonly maintained for a period of from about 10 to about 30 minutes. A polar liquid medium which is not a solvent for the copolymer is employed as the dispersant in the formation of the microfine powder support. These polar media are hydroxylic compounds and can include water, alcohols, polyols and mixtures thereof. The weight ratio of polar liquid medium to polymer ranges from about 0.8:1 to about 9:1 and, more preferably, from about 1:1 to about 5:1. It is particularly advantageous to use water as the dispersing medium or a liquid medium where water is the major component. The pressure of the process is not critical so long as a liquid phase is maintained. In general, the pressure can range from about 1 up to about 250 atmospheres. The process can be conducted at autogenous pressure or the pressure can be adjusted to exceed the vapor pressure of the liquid medium at the operating temperature. Most generally, with aqueous dispersions, the pressure will range from about 5 to about 120 atmospheres . To form acceptable dispersions, one or more dispersing agents are necessarily employed. Useful dispersing agents are nonionic surfactants which are block copolymers of ethylene oxide and propylene oxide. Preferably, these nonionic surfactants are water-soluble block copolymers of ethylene oxide and propylene oxide and have molecular weights greater than about 3500. Most will contain a major portion by weight of ethylene oxide and are obtained by polymerizing ethylene oxide onto preformed polyoxypropylene segments. The amount of nonionic surfactant employed can range from about 4 to about 50 percent, based on the weight of the copolymer. Most preferably, the nonionic surfactant is present in a concentration of from about 7 to about 45 percent, based on the weight of the copolymer. Useful nonionic surface active agents of the above type are manufactured and sold by BASF Corporation, Chemicals Division under the trademark Pluronic . These products are obtained by polymerizing ethylene oxide onto the ends of a preformed polyoxypropylic base. Both the molecular weight of the polyoxypropylene base and the polyoxyethylene segments can be varied to yield a wide variety of products. One such compound found to be suitable in the practice of the process of this invention is the product designated as F-98 wherein a polyoxypropylene of average molecular weight of 2,700 is polymerized with ethylene oxide to give a product of molecular weight averaging about 13,500. This product contains 20 weight percent propylene oxide and 80 weight percent ethylene oxide. Other effective Pluronic- surfactants include F-88 (M.W. 11,250, 20% propylene oxide, 80% ethylene oxide) , F-108 (M.W. 16,250, 20% propylene oxide, 80% ethylene oxide) , and P-85 (M.W. 4,500, 50% propylene oxide, 50% ethylene oxide) . These compounds, all containing at least about 50 weight percent ethylene oxide and having molecular weights of at least 4,500, are highly effective as dispersing agents for the aforementioned copolymers. It is also possible to employ products sold under the trademark Tetronic which are prepared by building propylene oxide block copolymer chains onto an ethylenediamine nucleus and then polymerizing with ethylene oxide. Tetronic ® 707 and Tetronic ® 908 are most effective for the present purposes. Tetronic ® 707 has a 30 weight percent polyoxypropylene portion of 2,700 molecular weight polymerized with a 70 weight percent oxyethylene portion to give an overall molecular weight of 12,000. Tetronic ® 908, on the other hand, has a 20 weight percent polyoxypropylene portion of 2,900 molecular weight polymerized with an 80 weight percent oxyethylene portion to give an overall molecular weight of 27,000. In general, useful Tetronic* surfactants have molecular weights above 10,000 and contain a major portion by weight of ethylene oxide. The powder-forming process may also be conducted in a continuous manner. If continuous operation is employed, the ingredients are continuously introduced to the system while removing the dispersion from another part of the system. The ingredients may be separately charged or may be combined for introduction to the autoclave. The particulate copolymer supports and especially the microfine spheroidal powders described above can be used to prepare any Ziegler-Natta catalyst composition. The supported catalysts of the present invention preferably comprise (a) an organometallic compound, complex or mixtures thereof; (b) a transition metal, transition metal compound or mixtures thereof; and (c) the functionalized copolymer support. One or more additional components such as electron donors or halogenating agents may also be present. Organometallic compounds suitable for use in the present invention include, for example, compounds of formulae I, II and III which are as follow: (I) R^tOR 3 )^. wherein M 1 is a metal of Group IA of the Periodic Table of Elements; R 2 and R 3 are the same or different and are hydrocarbyl groups, preferably containing from about 1 to about 20 carbon atoms and preferably selected from the group consisting of alkyl groups containing from about 1 to about 20, more preferably from about 1 to about 12, carbon atoms; alkenyl groups containing from about 2 to about 20, preferably from about 2 to about 12, carbon atoms; cycloalkyl or aryl groups containing from about 6 to about 20, preferably from about 6 to about 14, carbon atoms; or alkaryl or aralkyl groups containing from about 7 to about 20, preferably from about 7 to about 16, carbon atoms; and a is zero or 1; (II) R^M" (OR 3 ) β X a - < *, * «,, wherein M 11 is a metal of Group IIA or IIB of the Periodic Table of Elements; b and c are each zero, 1 or 2, subject to the provisos that at least one of b and c is other than zero and the sum of b and c is not more than 2; X is halogen, preferably fluorine, chlorine, bromine or iodine; R 2 and R 3 are as defined above in formula I, subject to the provisos that when b is 2, each R 2 can be the same or different, or when c is 2, each R J can be the same or different; and (III) RiM IXI (OR 3 ).Y 3 -c<_..-.) wherein M 111 is a metal of Group IIIA of the Periodic Table of Elements; d and e are each zero, 1, 2 or 3, subject to the provisos that at least one of d and e is other than zero and the sum of d and e is not more than 3; Y is hydrogen or halogen; and R 2 and R 3 are as defined in formula I, subject to the provisos that when d is 2 or 3 , each R 2 can be the same or different, or when e is 2 or 3, each R 3 can be the same or different. Organometallic compounds encompassed by formula I above include, for example: alkali metal alkyls, such as lithium alkyls (e.g., methyl lithium , ethyl lithium, butyl lithium, and hexyl lithium) ; alkali metal cycloalkyls, such as lithium cycloalkyls (e.g., cyclohexyl lithium) ; alkali metal alkenyls, such as lithium and sodium alkenyls (e.g., allyl lithium and allyl sodium) ; alkali metal aryls, such as lithium aryls (e.g. , phenyl lithium) ; alkali metal aralkyls, such as lithium and sodium aralkyls (e.g., benzyl lithium, benzyl sodium and diphenylmethyl lithium) ; alkali metal alkoxides, such as lithium and sodium alkoxides (e.g., lithium methoxide, sodium me hoxide and sodium ethoxide) ; alkali metal aryloxides, such as sodium aryloxides (e.g., sodium phenolate) ; and the like. Organometallic compounds within the scope of formula II above include, for example: Grignard reagents (e.g., methyl magnesium chloride, methyl magnesium bromide, methyl magnesium iodide, ethyl magnesium chloride, ethyl magnesium bromide, cyclohexyl magnesium chloride, allyl magnesium chloride, phenyl magnesium chloride, phenyl magnesium bromide and benzyl magnesium chloride) ; metal alkyls, such as dialkyl magnesium compounds (e.g., dimethyl magnesium, butyl ethyl magnesium and dibutyl magnesium) and dialkyl zinc compounds (e.g., diethyl zinc) ; metal alkoxides, such as magnesium alkoxides (e.g., magnesium methoxide and di-2-ethyl-l- hexyloxymagnesium) ; Hydrocarbyloxy metal halides, such as alkoxymagnesium halides (e.g., pentyloxymagnesium chloride, 2-methyl-1-pentyloxymagnesium chloride and 2- ethyl-1-hexyloxymagnesium chloride) , and the like. Organometallic compounds within the ambit of formula III above, where e is other than zero, include aluminum-n-butoxide, aluminum ethoxide, aluminum ethylhexoate, diethylaluminum ethoxide, diisobutylaluminum ethoxide, diisobutylaluminum 2,6-di- tert-butyl-4-methyl phenoxide, and the like; and where e is zero compounds of formula III-a below can be employed in the instant invention: (Ill-a) R2M Ii:t Y:,-* wherein R 2 is as defined in formula I, M 111 and Y are as defined in formula III and f is 1, 2 or 3, subject to the proviso that when f is 1, Y is X, as defined in formula II. Organometallic compounds within formula Ill-a above include for example: trimethylaluminum (TMAL) , triethylaluminum (TEAL) , triisobutylaluminum (TIBAL) , tridodecylaluminum, trieicosylaluminum, tricyclohexylaluminum, triphenylaluminum, triisopropenylaluminum, tribenzylaluminum, diethylaluminum hydride (DEAH) , diisobutylaluminum hydride (DIBAH) , dimethylaluminum bromide, diethylaluminum chloride (DEAC) , diisobutylaluminum bromide, didodecylaluminum chloride, dieicosylaluminum bromide, isopropylaluminum dibromide, ethylaluminum dichloride (EADC) , and the like. Other organometallic compounds outside the scope of generic formulae I-III are also contemplated for use in the present invention. The organometallic compounds outside the scope of generic formula I-III include, but are not limited to, ethylaluminum sesquichloride (EASC) , (C 2 H 5 ) ,Al 2 Cl 3 ; linear or cyclic aluminoxanes such as those described in U.S. Patent Nos . 4,897,455 to Wellborn, Jr. and 4,912,075 to Chang; and dimeric compounds of the formula (R' ) 2 -Al-0-Al- (R') 2 wherein each R' is the same or different and is an alkyl containing from about 1 to about 6, preferably from about 2 to about 4 , carbon atoms. Complexes of the forgoing mentioned organometallic compounds are also contemplated by the instant invention. For example, an organometallic compound of magnesium may be complexed with an organoaluminum halide to form a Mg-Al complex. The magnesium-aluminum complexes which may be used in the present invention are well known in the art and are disclosed in Aishima et al . , U.S. Patent No. 4,004,071 at column 3, lines 34-40 and column 3, lines 30-36, the contents of which are incorporated herein by reference. The complex is prepared according to the teachings of Ziegler et al . , Organometallic Compounds XXII: Organomagnesium-Aluminum Complex Compounds, Annalen der Chemie, 605, pp. 93-97 (1957) . Mixtures of suitable organometallic compounds can be used in the present invention. In a first preferred embodiment of the present invention, the organometallic compounds are the alkyls, alkoxides or aryls of magnesium or its complexes thereof. In a second preferred embodiment, an alkyl, alkoxide or aryl of magnesium (or its complexes) is utilized in conjunction with an alkyl, alkoxide or aryl of aluminum (or its complexes) . Of these preferred organomagnesium and organoaluminum compounds, magnesium dialkyls and aluminum trialkyls, wherein the alkyl moieties contain from about 1 to about 8 carbon atoms, are particularly preferred. Known transition metals or transition metal compounds employed in the preparation of Ziegler-Natta catalysts can be used for the catalysts of the invention. Suitable transition metal compounds are compounds of metals of Group IVB, VB, VIB or VIIB of the Periodic Table of the Elements. Illustrative transition metal compounds are compounds of titanium, vanadium, molybdenum, zirconium or chromium, such as TiCl 3 , TiCl 4 , alkoxy titanium halides, VC1 3 , VC1 4 , VOCl,, alkoxy vanadium halides, MoCl 5 , ZrCl 4 , HfCl 4 and chromium acetylacetonate. Mixtures of transition metal compounds to provide dual site bimetallic catalysts, such as titanium and vanadium-containing catalysts, can also be employed. Compounds of titanium and/or vanadium are especially useful for the catalysts of the invention. The Ziegler-Natta catalysts of this invention are generally employed with a cocatalyst, sometimes also referred to as a catalyst promoter or catalyst activator. The cocatalyst employed in the present invention contains at least one metal selected from Groups IB, IIA, IIB, IIIB, and IVB of the Periodic Table of Elements. Such cocatalysts are known and widely used in the polymerization art and can include metal alkyls, hydrides, alkylhydrides, and alkylhalides, such as alkyllithium compounds, dialkylzinc compounds, trialkylboron compounds, trialkylaluminum compounds, alkylaluminum halides, alkylaluminum hydrides, and the like. Mixtures of cocatalytic agents can also be employed. Illustrative organometallic compounds which can be used as cocatalyst include n-butyllithium, diethylzinc, di-n-propylzinc, triethylboron, trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, ethylaluminum dichloride, ethylaluminum dibromide, ethylaluminum dihydride, diethylaluminum chloride, di-n-propylaluminum chloride, and the like. Preferred cocatalysts are Group III B metal alkyls and alkyl metal halides, especially wherein the metal is aluminum and the alkyl group contains from about 1 to about 8 carbon atoms. Triethylaluminum and triisobutylaluminum are highly useful cocatalysts for the supported Ziegler-Natta catalysts of the invention and are particularly preferred. Cocatalysts are employed in amounts effective to promote (increase) the polymerization activity of the supported Ziegler-Natta catalyst. The amount of cocatalyst used can vary widely but most generally the molar ratio of the metal of the cocatalyst to the transition metal ranges from about 1:1 to about 500:1 and, more preferably, from about 5:1 to about 200:1. In the embodiment of the invention where aluminum alkyls or aluminum alkyl halides are employed as the cocatalyst with a titanium compound and magnesium compound, the Al/Ti molar ratio generally ranges from about 5:1 to about 100:1. The catalyst may be activated in-situ by adding the cocatalyst and supported catalyst separately to the polymerization or the supported catalyst and activator may be pre-contacted before introduction to the polymerization reactor. Cocatalysts for polymerization may be employed singly in the manner described, or in concert with other such modifiers, activators or promoters to enhance activity or influence resin properties. The use of cocatalyst modifiers is described, e.g. in U.S. Patent No. 5,334,567 to Menon et al . regarding halosilanes; U.S. Patent Nos. 4,559,318 to Smith et al . , 4,866,021 to Miro et al . , 5,006,618 to Miro et al . regarding halocarbons; U.S. Patent No. 4,250,287 to Matlack regarding aromatic esters; U.S. Patent Nos. 3,786,032 to Jennings et al . and 4,611,038 to Brun et al . regarding additional organometallic activators, and U.S. Patent No. 5,275,991 to Buehler et al . regarding alkoxysilanes . Preferred compounds which may be employed as cocatalyst modifiers include halocarbons such as carbon tetrachloride, carbon tetrabromide, dichloromethane, dibromomethane, 1, 1, 1-trichloroethane and a number of commonly available chlorofluorocarbons (CFC's) and hydro-chlorofluoracarbons (HCFC's) ; halosilanes such as silicon tetrachloride, trichlorosilane, dichlorosilane; and alkoxysilanes such as dimethoxysilane, diethoxysilane, diisopropoxysilane, trimethoxysilane and tetramethoxysilane, and more preferably the alkoxysilane is diisopropyldimethoxysilane, diisobutyldi- methoxysilane, phenyltriethoxysilane and cyclohexyltri¬ methoxysilane. Except for use of the particulate olefin- acrylate copolymer supports, the Ziegler-Natta catalysts of the invention are prepared utilizing conventional organometallic compounds and transition metal components, in accordance with standard catalyst-forming procedures. Typically, the support is contacted with the organometallic compound in an aliphatic C 5 . e hydrocarbon. When this contact is complete, the product is contacted with the transition metal compound. The organometallic compound and the transition metal compound are generally dissolved in an aliphatic hydrocarbon for introduction. A slight exotherm may be observed upon contacting the organometallic compound with the support material. The support may be allowed to remain in contact with the organometallic compound for periods of up to 20 hours or more but reaction is sufficiently complete within about 30 minutes. All or a portion of the aliphatic hydrocarbon may be removed after contacting with the organometallic compound and the intermediate catalyst product may be washed, if desired. While it is not necessary, it is possible to wash and/or dry the catalyst precursor before contacting with the transition metal compound. In general, it has been observed that resins with higher bulk densities are produced using catalysts which have been prepared without washing between the contacting steps. If all or part of the aliphatic hydrocarbon is removed from the catalyst precursor, it will be redispersed in fresh, aliphatic hydrocarbon prior to contacting with the transition metal compound. A change in color of the catalyst, e.g., from pale yellow to brown when TiCl 4 is used, is usually observed upon contacting with the transition metal compound; however, the hydrocarbon medium will typically remain colorless. Reaction with the transition metal compound will generally be complete in 30 minutes or less; however, extended contact times do not appear to adversely affect the catalysts. While it is not necessary, the supported catalyst may be washed and dried after recovery. After the transition metal is reacted, the supported catalyst is recovered for use in polymerizations. Supported catalysts obtained in this manner are fine, free-flowing powders having particles not differing substantially in size, shape and particle size distribution from that of the copolymer support material used for their preparation. The supported catalysts can contain from about 0.25 up to about 25 weight percent transition metal. More typically, transition metal contents will range from about 0.5 to about 10 percent. In a preferred embodiment of the invention where the organometallic component is a magnesium compound, magnesium contents will range from about 0.1 to about 25 and, more preferably, about 0.25 to about 10 weight percent and magnesium/transition metal molar ratios will range from about 4:1 to about 0.25:1 and, more preferably, from about 2.25:1 to about 0.5:1. In one highly useful embodiment of the invention, the magnesium compound has the structural formula R 2 Mg wherein R is an alkyl group containing from about 1 to about 8 carbon atoms and the transition metal compound has one of the following structural formulas: Ti(OR 4 ) x X y ; or V(0R 4 )_(0) m X n wherein R 4 is an aliphatic or aromatic hydrocarbyl group containing from about 1 to about 12 carbon atoms; X is Cl , Br, or I ; x is 0, 1 or 2, y is 1 to 4 inclusive; x+y=3 or 4; 1 is 0 or 1-5; m is 0 or 1; and n=(5-l-2m) or 4 or 3 when 1=0, m=0. Suitable titanium compounds encompassed by the above formula are TiCl 3 , TiCl 4 , Ti(0CH 3 )Cl 3 Ti (0C 6 H 5 ) Cl 3 , Ti(OC 2 H s ) 2 Cl 2 , Ti(OC 2 H s ) 3 Cl, Ti (0C 4 H 2 C1 2 and Ti (OC 4 H 9 ) 4 . TiCl 4 is especially useful in the preparation of the catalyst of this invention. Suitable vanadium compounds encompassed by the above formula include vanadium oxyhalides, vanadium carboxylates and vanadium halides. VC1„ and V0C1 3 are particularly preferred in the present invention. The formation of the catalyst may also involve reaction with known electron donors including alcohols, phenols, ketones, aldehydes, carboxylic acids, carboxylic acid esters, ethers, and the like. Particularly useful electron donors include the alkyl esters of aliphatic carboxylic acids, aliphatic alcohols, aliphatic ketones and aliphatic ethers. Ziegler-Natta catalysts typically contain halogen, primarily chlorine. The source of the halogen most commonly is provided by the magnesium or transition metal compound. Halogenated titanium and vanadium compounds are particularly useful halogen sources. Halogen can, however, be supplied by a halogenating agent such as hydrogen halides, organohalides, aluminum halides, silicon halides or phosphorus halides. The catalyst of the invention can be used in virtually any polymerization procedure where supported Ziegler-Natta catalysts have heretofore been utilized. This includes both gas phase (stirred or fluidized bed) polymerizations and solution polymerizations. They are highly effective for stirred bed and fluidized bed polymerization processes which are carried out in the substantial absence of a liquid reaction medium. Such procedures are well known and described in the prior art and may be conducted in a single reactor or in multiple reactors connected in series. The catalysts are equally effective for use in particle form (slurry) processes which are also described in the prior art. These polymerizations are carried out in a liquid organic medium in which the catalyst is suspended. A pressure sufficient to maintain the organic diluent and at least a portion of the monomer in the liquid phase is maintained. The supported catalysts of the invention are useful for the preparation of homopolymers and copolymers of alpha-olefins containing from about 2 to about 8 carbon atoms. Most preferably, they are used to produce polymers comprised predominantly of ethylene and/or propylene with densities ranging from about 0.90 to about 0.97 and having a desirable balance of rheological and physical properties making such polymers useful in applications such as blow molding, injection molding, rotomolding, rotolining, extrusion, coextrusion, film forming and the like. Moreover, the polymers produced herein have the same morphology as the supported catalyst used in the polymerization process. That is, the polymers produced by the instant process have substantially spherical particles and a median particle size which depends on both the median particle size of the catalyst particles and the amount of polymer produced per unit amount of catalyst employed in the polymerization. The median particle size can thus range from about 10 to about 5000 microns. Such polymer particles produced in the present invention possess a better bulk density and fluidization compared to prior art polymer particles prepared from conventional polymeric supported catalysts. Furthermore, the polymer particles produced in the present invention are compatible with the functionalized polymeric supports. Thus, no residual gels are formed during the polymerization process which are attributable to the catalyst support. The following examples are given to illustrate the scope of the invention. As will be apparent to those skilled in the art, numerous variations are possible and thus the scope of this invention should not be limited thereto. PREPARATION OF PARTICULATE SUPPORTS An electrically heated two-liter Parr [trademark] pressure autoclave equipped with a thermowell and thermocouple connected to a digital display was used to prepare the microfine powder supports following the general procedure set forth in the U.S. Patent No. 3,422,049, the contents of which are incorporated herein by reference. The autoclave was equipped with an agitator and a Strahman [trademark] valve to permit rapid discharge of the hot polymer dispersion into a 5 gallon stainless steel discharge tank which was connected to the reactor via a 1" diameter stainless steel line. The hot dispersion was rapidly discharged into this tank containing approximately 6.5 liters of 20-23°C water at the completion of each run. The hot dispersion was introduced below the surface of the water. The autoclave agitator used had three, six-bladed, impellers and was driven by a 2 HP DC variable speed motor. The powder produced in this operation was analyzed using laser light scattering to measure the size distribution thereof by volume. This technique used the principle of diffraction of the particles as the measurement means. A Model 2600C Malvern Particle Size Analyzer with proper lens configuration for the expected particle size interfaced with a computer was used. It read the diffraction pattern and digitally performed the necessary integrations. For the powder analysis, water was charged to the water bath and circulated through the sample measuring chamber. After obtaining the baseline measurement, the agitator and sonic vibrator were activated and the copolymer powder was added to the water bath until the obscuration reading was 0.3. Mixing and circulation were controlled to obtain acceptable dispersion without excessive foaming. A drop of liquid detergent was added to facilitate dispersion. After eight minutes agitation, measurements were commenced and the size distribution data was automatically tabulated. The cumulative volume undersize and volume frequency was tabulated for 32 size classes together with useful derived parameters. A logarithmic plot was also produced. Duplicate runs were made for each copolymer powder sample. The particle size reported in the examples was the median diameter D(v,0.5) for the volume distribution curve. The range reported in the examples was for 80 percent of the volume distribution curve, i.e., from D(v,0.1) to D(v,0.9) . In other words, ten percent of the powder particles were sized below the recited lower limit and 10 percent of the powder particles were larger than the upper recited particle size limit. This range provides a convenient means of comparing powders . Following the procedure of Example I of U.S. Patent No. 3,422,049, particulate microfine supports were produced from the following ethylene-acrylate and ethylene-vinyl acetate copolymers. 1 Determined by Differential Scanning Calori etry; ASTM D-3417 and D-3418 2 ASTM D-155, condition B For each powder preparation, 450 grams of the copolymer was combined with 180 grams dispersing agent (Pluronic" F-98) and 810 grams water. The reactor was sealed, heated and when the temperature reached about 200°C agitation was commenced. Temperature (°C) and rate of agitation (rpm) for each run as well as the median 5 particle diameter (microns) and particle size range (in microns for 80 percent of the volume distribution curve) for the microfine powder produced are provided in Table 1. The powders thus prepared, designated as ϋ Copolymer Supports A-G, were employed in the preparation of the supported Ziegler-Natta catalysts in the examples 5 which follow. All of the above-prepared copolymer supports were free-flowing powders comprised of discrete particles having spherical morphology, i.e., the individual particles are spherical or substantially spherical in shape. Copolymer Support A was also more fully characterized and found to have a surface area of 2.1 m 2 /g, a pore volume of 0.021 cc/g and average pore radius of 203 A by the BET method. These measurements were carried out using an Autosorb-6 [trademark] instrument and the physical measurements were determined using the techniques described in S. Lowel et al . , "Powder Surface Area and Porosity", 2nd Ed., Chapman and Hall, London, 1984. Furthermore, the copolymer support had a weight average molecular weight (M w ) of 110,400, number average molecular weight <M n ) of 24,700 and MWD (M„/M n )of 4.50. Copolymer Supports A, B and D-G were utilized as obtained from the powder-forming process. A commercial microfine EVA powder (Copolymer Support H) was also included. Additionally, a particulate support was obtained by cryogenically grinding EMA1. Cryogenic grinding of this sample was conducted by mechanical means, using a Wiley mill which was equipped with a recirculating refrigerant. The polymer sample, i.e. EMA1, was ground along with dry ice so as to not incur polymer melting. The polymer was also ground so as to pass through a 20 mesh size screen. The resulting ground powder, identified as Copolymer Support I (not shown in Table 1) and having an average particle size of 590 microns and particle size distribution of 297 to 840 microns, was also employed in the preparation of Ziegler-Natta catalysts in the examples which follow. TABLE 1 D(v, 0.5) D(v,0.1) - D(v,0_9l PREPARATION OF SUPPORTED CATALYSTS AND POLYMERIZATIONS EXAMPLE I: To illustrate the preparation of a supported Ziegler-Natta catalyst, 5.38 grams of Copolymer Support A was slurried with 75 ml dry heptane under a nitrogen atmosphere in a 250 ml round-bottom flask equipped with a stirring bar. Fifteen (15) ml of 0.633M butyl ethyl magnesium, commercially available from AKZO Chemicals Inc., under the designation MAGALA [trademark] BEM, in heptane was added under nitrogen at room temperature whereupon the support quickly developed a faint yellow tint and a slight exotherm was observed. After stirring for 20 hours, the catalyst precursor was recovered by filtration, washed once with 100 ml heptane, and then re-slurried in 100 ml fresh heptane. Two (2) ml 1.0M TiCl„ in heptane was then added with vigorous stirring and the pale yellow support immediately turned brown. After 30 minutes the supported polymer was recovered by filtration, washed two times with 75 ml heptane and then dried under vacuum. Analysis showed the catalyst to contain 1.44% Mg and 1.37% Ti . The molar ratio of Mg/Ti was 2.06. This preparative example illustrates that a substantial portion of the organometallic compound interacts with the support particles. Washing the catalyst after both the addition of the organometallic compound as well as after the addition of the transition metal compound in a solvent suitable for the dissolution of both free reagents serves to remove virtually all materials which might otherwise be considered to interact independently of the support. Analysis of the final catalyst composition revealed that the catalyst retained 33% and 77% of the magnesium and titanium employed, respectively. The supported catalyst was used to prepare ethylene homopolymer and copolymers of ethylene and butene-l. Four polymerizations, identified as a-d, were carried out in a one-liter stirred autoclave charged with 500 ml dried, deoxygenated isobutane. For the copolymerizations, an amount of isobutane was used to bring the total volume of comonomer and isobutane to 500 ml . Hydrogen was added to control molecular weight and triethylaluminum (TEAL) was used as the cocatalyst. Polymerizations were carried out at 80°C and 500 psig. Ethylene gas was used to maintain this pressure. Upon completion of the polymerization, the reactor was vented and cooled to ambient temperature to recover the copolymer. Details of each polymerization and characteristics of the resins produced are provided in Table 2. TABLE 2 Determined by ASTM D-1238, Condition E, reported as g/10 minutes. MIR = HLMI/MI; HLMI was determined by ASTM D-1238, Condition F, reported as g/10 minutes. Determined by floatation in a density gradient column after annealing an extrudate sample for 30 minutes at 100°C to approach equilibrium crystallinity. Measurements were performed on an unmodified reactor powder sample by pouring the sample through a 33 mm ID funnel into a 100 cc stainless steel cup without tapping or shaking, then leveling off the top with a straight edge and weighing by difference. Values reported as the mean of two measurements in g/cm'. Weight and number average molecular weight determinations, i.e., M w and M„, were made using a Waters GPC on a mixed sized, crosslinked divinylbenzene column with 1, 2, 4-trichlorobenzene as a solvent at 135°C with a refractive index detector. The ratio of M w vs M„ l . e MWD , was also determined by GPC. EXAMPLES II-IV: To demonstrate the ability to vary the catalyst compositions, three supported catalysts were prepared using different copolymer supports and varying levels of magnesium and titanium. The same reagents and procedure as described in Example I were employed. The amount of each reagent employed in the preparation of the supported catalysts is set forth in Table 3. The supported catalysts were used to homopolymerize ethylene. The polymerization results and characteristics of the polyethylene resins produced are also provided in Table 3. Sieved using 200 mesh screen so that the average particle size was reduced to 68 microns. EXAMPLE V: A supported catalyst was prepared utilizing Copolymer Support A. The reagents used were the same as used in Example I except that the catalyst precursor obtained after reaction of the support with BEM was not washed with additional heptane and the resulting supported catalyst, obtained after reaction with the TiCl 4 , was not washed. After both reactions, the heptane was removed by stripping under vacuum. After removing the solvent from the catalyst precursor by evaporating under vacuum (with BEM) , the catalyst precursor was re-slurried with 50 ml fresh heptane before addition of TiCl 4 . After the second reaction (with TiCl 4 ) , stripping was continued to dryness. For the catalyst preparation, 5 grams Copolymer Support A, 5 ml BEM and 2 ml TiCl 4 were used. The resulting catalyst contained 1.34% Mg, 1.48% Ti and the Mg/Ti molar ratio was 1.77. The catalyst was used to polymerize ethylene and polymerization details are provided in Table 4. EXAMPLE VI: Using the modified catalyst preparation procedure of Example V, a supported catalyst was prepared using 5 grams Copolymer Support A, 5 ml BEM and 4 ml TiCl 4 . The catalyst product contained 1.31% Mg, 2.80% Ti and the Mg/Ti molar ratio was 0.93. The catalyst was used to homopolymerize ethylene and polymerization details are provided in Table 4. EXAMPLE VII: Following the procedure of Example I, cryogenically ground Copolymer Support I (5.68 grams) was reacted with 10 ml BEM and 2 ml TiCl 4 . The resulting supported catalyst (0.29% Mg; 1.36% Ti, molar ratio Mg/Ti 0.42) was evaluated as a catalyst in the polymerization of ethylene. The results of this polymerization are reported in Table 4. EXAMPLES VIII TO XIII: Modifying the general procedure of Example V, a series of supported catalysts were prepared using Copolymer Support A and the magnesium and titanium reagents of Example I. The amount of each of these components are identified below in the discussion of each of these catalysts. Any changes in the procedure of Example V and the analysis of each of the catalysts is also provided therein. The results obtained with each of the supported catalysts in the homopolymerization of ethylene or copolymerization of ethylene and butene-1 are reported in Table 4. Supported Catalyst VIII: 5.0 grams Copolymer Support A 5.0 ml BEM 2.0 ml TiCl 4 Prior to the contacting with TiCl 4 , 5 ml 0.5M butanol in heptane was added and contacted at room temperature with agitation for 30 minutes. The supported catalyst contained 2.03% Ti and 1.20% Mg. Supported Catalyst IX: 5.0 grams Copolymer Support A 5.0 ml BEM 2.0 ml TiCl 4 Prior to contacting with TiCl 4 , 1.25 ml 2.0M SiQl in heptane was added and contacted at room temperature with agitation for 30 minutes. The supported catalyst contained 1.49% Ti, 1.29% Mg and 0.203% Si. Supported Catalyst X: 5.0 grams Copolymer Support A 5.0 ml BEM 2.0 ml TiCl 4 Contact with both the BEM and TiCl was carried out at 40°C for 30 minutes and 15 minutes, respectively. The supported catalyst was recovered by decanting the supernatant heptane after the catalyst settled and purging with nitrogen while heating the catalyst at 40°C. The supported catalyst ^contained 1.56% Ti and 1.48% Mg. Supported Catalyst XI: 5.0 grams Copolymer Support A 3.0 ml MAGALA [trademark] 7.5E (7.5:1 ratio of di-n- butyl magnesium to TEAL in heptane) 2.0 ml TiCl 4 For this preparation, the copolymer support was slurried in 75 ml pentane. After contacting the support with the MAGALA for 45 minutes at room temperature, the TiCl 4 was added directly to the slurry and agitation continued for 30 minutes. The supported catalyst was recovered by removing pentane using the a nitrogen purge. The supported catalyst contained 1.30% Ti , 1.07% Mg and 0.20% Al. Supported Catalyst XII : 5.0 grams Copolymer Support A 6.0 ml (0.59M) 2-methylpentyloxymagnesium chloride in heptane 4.0 ml TiCl 4 The copolymer support was slurried in 75 ml pentane and contacted with the 2-methylpentyloxymagnesium chloride at room temperature for one hour with agitation. The catalyst precursor was then stripped under vacuum to substantial dryness and washed with 75 ml fresh pentane and then re-slurried in 75 ml pentane prior to addition of the TiCl 4 . The supported catalyst was recovered by purging with nitrogen at room temperature to remove pentane. The catalyst contained 2.71% Ti and 1.05% Mg. Supported Catalyst XIII: 15.0 grams Copolymer Support A 15 ml BEM 6 ml TiCl 4 The copolymer support was slurried in 150 ml pentane and contacted with BEM for one hour at room temperature with agitation and then with the TiCl„ and additional stirring was conducted for 30 minutes at room temperature with agitation. The supported catalyst was recovered by purging with nitrogen at room temperature . The supported catalyst contained 1.31% Ti and 1.25% Mg. EXAMPLE XIV: A supported vanadium catalyst was prepared utilizing the copolymer supports of the invention. To a slurry of 5.0 grams of Copolymer Support A in 80 ml heptane were added the following in the order indicated: 3.27 ml (1.07M) MAGALA 7.5E; 6.32 ml (0.554M) TEAL in heptane; 7.48 ml (0.535M) VC1 4 in heptane; and 2.0 ml (0.50M) n-butanol in heptane. The additions were made at room temperature at 30 minute intervals while vigorously agitating the slurry. When the additions were complete and after the final contact period, the catalyst was stripped under vacuum to remove solvent . The dried supported catalyst contained 5.62% V, 1.07% Mg and 1.59% Al . Polymerization details obtained using the supported vanadium catalyst are reported in Table 4. EXAMPLE XV: To demonstrate the ability to use other olefin-acrylate copolymers in the preparation of the supported catalysts of the invention, 5 grams Copolymer Support E was slurried with 75 ml pentane and contacted with 5 ml (0.633M) BEM for 30 minutes at room temperature while stirring. Two (2.0) ml (1.0M) TiCl 4 was then added and stirred for an additional 30 minute period. The dried supported catalyst which contained 1.36% Ti and 1.19% Mg was evaluated for the polymerization of ethylene. Detarils of the polymerization and results are provided in Table 4. EXAMPLE XVI: Using a procedure identical to that described in Example XV, except that the copolymer support used was Copolymer Support F, a supported catalyst was prepared containing 1.34% Ti and 1.23% Mg. The supported catalyst was used to polymerize ethylene and polymerization details and results are provided in Table 4. EXAMPLE XVII: Using a procedure identical to that described in Example XV, except that the copolymer support used was Copolymer Support D, a supported catalyst was prepared containing 1.28% Ti and 1.31% Mg. Ethylene was polymerized using the supported catalyst and polymerization details and results are provided in Table . EXAMPLE XVIII: Using a procedure identical to that described in Example XV, except that the copolymer support used was Copolymer Support G, a supported catalyst was prepared containing 1.23% Ti and 1.30% Mg. The supported catalyst was used for the polymerization of ethylene and polymerization details and results are provided in Table 4. EXAMPLE XIX: This example demonstrates the use of the copolymeric ethylene-vinyl acetate Support Material H of Table I. The catalyst of this example was prepared by slurrying five (5.0) grams of the EVA material H with 100 ml dry heptane under a nitrogen atmosphere in a 250 ml roundbottom flask equipped with stirring bar. Five (5.0) ml of 0.633 M BEM was added and the resultant mixture was stirred for 30 minutes at room temperature under nitrogen. Thereafter, 0.2 ml of 1.0M TiCl 4 in heptane was added, changing the color of the copolymeric support to a dark brown. After a 30 minute interval, heptane was removed by purging with nitrogen gas and drying the resultant catalyst . The supported catalyst prepared using the above deposition process contained 1.29% Ti and 1.33% Mg. This catalyst was then used to homopolymerize ethylene, the results and details of which are summarized in Table 4. EXAMPLE XX: Another supported catalyst was prepared using the EVA support material used in Example XIX except that the catalyst was prepared using a filtration procedure. In accordance with this procedure, the slurry containing EVA, BEM and heptane was allowed to react overnight at room temperature under nitrogen. After this reaction, the slurry was filtered and washed once with 100 ml of dried heptane. The washed material was thereafter re-slurried in 100 ml of heptane and 2 ml of a solution of 1.0M TiCl. in heptane was added, changing the color of the resin to a light brown. This mixture was stirred for 30 minutes, filtered and then washed with 100 ml of heptane. The catalyst thus formed was vacuum dried to leave a flaxen- yellow powder containing 1.57% Ti and 0.47% Mg. As with the catalyst of the proceeding example, the catalyst prepared above was used to homopolymerize ethylene. The polymerization details and results are tabulated in Table 4. EXAMPLE XXI: In this example, a supported vanadium catalyst was prepared utilizing the EVA material of Table I. To a slurry of 5.0 grams of the Copolymer Support H in 80 ml of heptane were added the following in the order indicated: 12.7 ml (0.551M) MAGALA 7.5 E; 10 ml (0.5M) n-butanol in heptane; and 1.0 ml (0.5M) VC1 4 in heptane. The additions were made at room temperature at 30 minute intervals while vigorously stirring the slurry. When the additions were complete and after the final contact period, the catalyst was dried under vacuum to remove the solvent. The dried support catalyst contained 2.03% V, 0.95% Mg and 0.22% Al . Polymerization details using this supported vanadium catalyst are reported in Table 4. I I 1.25 ml of 1.0 M dlbronethane added along with cocatalyst to reactor COMPARATIVE EXAMPLE I: A supported catalyst was prepared in accordance with Example I, except that 10.0 grams of a microfine, spheroidal high density polyethylene powder (HDPE) made by the same dispersion process as used for Copolymer Support A and having a median particle diameter of 40 microns was used as the support material. Twenty (20.0) ml of 0.633 M BEM was added to the slurried support under nitrogen at room temperature. No color change or exotherm was observed during this contacting step, which was allowed to proceed for 20 hours. After this time period, the heptane was filtered off. The Mg-treated polymer was then washed with 100 ml of heptane, filtered, and re-slurried once again in heptane. Four (4.0) ml of 1.0 M TiCl 4 in heptane was then added to the treated support with vigorous stirring and the support immediately upon contact changed to an off-white shade. After 30 minutes of rapid stirring, the heptane was filtered off. The recovered supported material was washed twice with heptane (75 ml in each wash) , then dried in vacuo. Analysis showed that the catalyst contained 0.038% Ti and 0.042 Mg. This supported catalyst was then used to homopolymerize ethylene, the results and details of which are shown in Table 4. The results of this comparative example clearly indicate that supported catalysts of the instant invention are vastly superior in terms of reactivity compared to supported catalysts that are used conventionally in the prior art, as evidenced by the supported catalyst of this comparative example. COMPARATIVE EXAMPLE II: The supported catalyst of this comparative example was prepared in accordance with the procedure of Example I, except that 5.1 grams of a commercially available, spheroidal poly (methyl- methacrylate) (PMMA, MPS = 164 microns) supplied by Aldrich was used as the support material. Five (5.0) ml of 0.633 BEM was added to the slurried support under nitrogen at room temperature. No color change or exotherm was observed. The reaction was allowed to proceed for 20 hours, after which the heptane was filtered off. The treated polymer was washed once with 100 ml of heptane, filtered, then re-slurried again in heptane. Three (3.0) ml of 1.0 M TiCl 4 in heptane was added to the re-slurried heptane with vigorous stirring. No color change of either the support or heptane was observed. After 30 minutes of rapid stirring, the heptane was filtered off. The recovered supported material was washed twice with heptane (two 75 ml portions) and then dried in vacuo. The supported catalyst contained 0.013% Ti and 0.017% Mg. This supported catalyst was then used to homopolymerize ethylene. The polymerization results and details are set forth in Table 4. As in CEI, the supported catalyst of this comparative example was inactive in polymerizing ethylene compared to the catalysts of the present invention. EXAMPLE XXII: In this example, the catalyst of Example II was utilized as the catalytic agent in the gas phase polymerization of ethylene. The polymerization was conducted in a 2.5 liter stirred gas phase reactor. The cocatalyst TEAL (3.0 ml) was added to the reactor containing a 200 gram bed of polyethylene; the reactor was pressurized with nitrogen to a pressure of 142 psig (0.334 M) . Hydrogen (58 psi, 0.136 M) was then added, and ethylene was fed slowly into the reactor. The catalyst (0.6 grams) was injected into the reactor and ethylene was fed on demand into the reactor to maintain a total reactor pressure of 377 psig at a reactor temperature of 80°C (ethylene partial pressure of 176 psi, or 0.416 M) . Polymerization was continued under these conditions until 300 grams of polymer was produced. The reactor was thereupon vented and 300 grams of powder were removed from the reactor, leaving a 200 gram bed. A minimum of 4 runs were made with the catalyst to ensure adequate turnover of the seed bed. The results of this gas phase polymerization are summarized hereinbelow: PE Productivity rate 243 grams PE/g-hr MI 0.7 MIR 38.6 Density 0.9586 g/cc Bulk density 0.358 g/cc Mean Particle Size 818 microns (Malvern Light Scattering) 152, 908 21, 032 MWD 7.3 The above preferred embodiments and examples are given to illustrate the scope and spirit of the invention. These embodiments and examples will make apparent to those skilled in the art other embodiments and examples, which are also within the contemplation of the present invention. Therefore, the present invention should be limited only by the appended claims.

Claims: What is claimed is: 1. A supported Ziegler-Natta catalyst useful for polymerizing olefins comprising: (a) an organometallic compound, complex or mixtures thereof; (b) a transition metal, a transition metal compound or mixtures thereof; and (c) a particulate olefin copolymer support comprised of discrete particles having a median particle size ranging from about 1 up to about 1500 microns, pore volume less than 0.1 cc/g and surface area of less than 15 m 2 /g, and wherein said olefin copolymer has a melt index of about 0.1 to about 400 and containing from about 50.1 to about 99.9 weight percent C 2 . 3 or-olefin and from about 0.1 to about 49.9 weight percent of a monomer selected from the group consisting of a vinyl ester and an acrylate . 2. The supported Ziegler-Natta catalyst of Claim 1 wherein said vinyl ester is vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pentanoate or vinyl hexanoate. 3. The supported Ziegler-Natta catalyst of Claim 1 wherein said acrylate has the formula 0 5 CH,=CRC0R ] wherein R is hydrogen or methyl and R 1 is an alkyl group having from about 1 to about 12 carbon atoms or an aryl group having from about 6 to about 12 carbon atoms. Q . The supported Ziegler-Natta catalyst of Claim 3 wherein R is hydrogen and R 1 is a Cj, 4 alkyl group. 5 5. The supported Ziegler-Natta catalyst of Claim 4 wherein said acrylate is methyl acrylate. 6. The supported Ziegler-Natta catalyst of Claim 1 wherein said particles range in size from about 1 to about 1000 microns and the olefin copolymer contains from about 70 to about 99 weight percent C 2 . 3 c.-olefin and from about 1 to about 30 weight percent of said monomer. 7. The supported Ziegler-Natta catalyst of Claim 6 wherein said olefin copolymer contains from about 80 to about 95 weight percent ethylene and from about 5 to about 20 weight percent of said monomer. 8. The supported Ziegler-Natta catalyst of Claim 1 wherein said olefin copolymer is selected from the group consisting of ethylene-methyl acrylate, ethylene- ethyl acrylate, ethylene vinyl acetate and ethylene-n- butyl acrylate copolymers. 9. The supported Ziegler-Natta catalyst of Claim 1 wherein the support is a microfine powder comprised of particles which are spherical or substantially spherical and having a median particle size from about 1 to about 500 microns, from about 5 to about 300 microns or from about 20 to about 200 microns. 10. The supported Ziegler-Natta catalyst of Claim 1 wherein said organometallic compound has at least one of the following formulae: (I) R=M T (0R 3 ) x _. wherein M 1 is a metal of Group IA of the Periodic Table of Elements; R 2 and R are the same or different and are hydrocarbyl groups containing from about 1 to about 20 carbon atoms, alkenyl groups containing from about 2 to about 20 carbon atoms, cycloalkyl or aryl groups containing from about 6 to about 20 carbon atoms, or alkalyl or aralkyl groups containing from about 7 to about 20 carbon atoms; a is zero or 1; (II) R£M i:t (0R 3 ) e X_._ (1>^o . wherein M 11 is a metal of Groups IIA or IIB of the Periodic Table of Elements; b and c are each zero, 1 or 2, subject to the proviso that at least one of b and c is other than zero and the sum of b and c is not more than 2; X is a halide; and R 2 and R 3 are as defined above in formula I, subject to the proviso that when b is 2, each R 2 can be the same or different or when c is 2, each R 3 can be the same or different; and (III) R_iM IXI (OR 3 ).Y 3 -,«_ * ., wherein M 111 is a metal of Group IIIA of the Periodic Table of Elements; d + e are each zero, 1, 2 or 3, subject to the provisos that at least one of d + e is other than zero and the sum of d and e is not more than 3; Y is hydrogen or halide; and R 2 and R 3 are as defined above in formula I, subject to the provisos that when d is 2 or 3 , each R- can be the same or different, or when e is 2 or 3, each R 3 can be the same or different. 11. The supported Ziegler-Natta catalyst of Claim 10 wherein the organometallic compound has the formula: wherein M 11 is magnesium . 12. The supported Ziegler-Natta catalyst of Claim 11 wherein the organometallic compound is butylethyl magnesium or dibutyl magnesium. 13. The supported Ziegler-Natta catalyst of Claim 10 wherein the organometallic compound has the formula: R_jM ιa:ι (OR 3 ).Y 3 . t __-*-_> ) wherein M ι is aluminum. 14. The "supported Ziegler-Natta catalyst of Claim 13 wherein the organometallic compound is triethylaluminum, a mixture of butylethyl magnesium and triethylaluminum, or a mixture of dibutylmagnesium and triethylaluminum. 15. The supported Ziegler-Natta catalyst of Claim 1 wherein the transition metal or transition metal compound contains at least one metal from Group IVB, VB, VIB or VIIB of the Periodic Table of Elements. 16. The supported Ziegler-Natta catalyst of Claim 15 wherein the transition metal compound has the formula Ti(0R 4 ) x X y wherein R 4 is an aliphatic or aromatic hydrocarbyl group containing from about 1 to about 12 carbon atoms, X is Cl, Br, or I, x is 0, 1, or 2 , y is 1 to 4 inclusive, and x + y = 3 or . 17. The supported Ziegler-Natta catalyst of Claim 16 wherein the transition metal compound is TiCl., . 18. The supported Ziegler-Natta catalyst of Claim 15 wherein the transition metal compound has the formula V (OR 4 ) , (0) ... (X) n wherein R is an aliphatic or aromatic hydrocarbyl group containing from about 1 to about 12 carbon atoms; X is Cl, Br or I ; 1 is 0 or 1 to 5; m is 0 or 1; and n=(5-l-2m) or 4 or 3 when 1=0, m=0. 19. The supported Ziegler-Natta catalyst of Claim 18 wherein the transition metal compound is VC1 4 . 20. The supported Ziegler-Natta catalyst of Claim 1 further comprising an electron donor selected from the group consisting of alcohols, phenols, ketones, aldehydes, carboxylic acids, carboxylic acid esters and ethers . 21. The supported Ziegler-Natta catalyst of Claim 1 further comprising at least one halogenating agent selected from the group consisting of aluminum halides, hydrogen halides, organohalides, silicon halides and phosphorous halides. 22. The supported Ziegler-Natta catalyst of Claim 9 wherein the particulate support is obtained by: (a) heating the olefin copolymer to above the melt point of the copolymer with a nonionic surfactant which is a block copolymer of ethylene oxide and propylene oxide and a polar liquid medium which is not a solvent for the copolymer, said nonionic surfactant present in an amount from about 4 to about 50 percent based on the weight of the copolymer, and the weight ratio of said polar liquid medium to copolymer ranging from about 0.8:1 to about 9:1; (b) dispersing the mixture to produce droplets of desired size; and (c) cooling the dispersion to below the melt point of the copolymer. 23. The supported Ziegler-Natta catalyst of Claim 22 wherein the heating step is conducted at a temperature from about 175°C to about 250°C. 24. The supported Ziegler-Natta catalyst of Claim 22 wherein the polar liquid medium is water, alcohols, polyols or mixtures thereof. 25. The supported Ziegler-Natta catalyst of Claim 22 wherein the nonionic surfactant is present in an amount from 7 to 45 percent based on the weight of the copolymer, and the weight ratio of said polar liquid medium to copolymer ranging from about 1:1 to about 5:1. 26. An alpha-olefin polymerization catalyst system comprising the supported catalyst of Claim 1 and at least one cocatalyst compound containing a metal from Groups IB, IIA, IIB, IIIB or IVB of the Periodic Table of Elements. 27. The alpha-olefin polymerization catalyst system of Claim 26 wherein the cocatalyst is a metal alkyl, metal hydride, metal alkylhydride or metal alkylhalide. 28. The alpha-olefin polymerization catalyst system of Claim 27 wherein the cocatalyst is a Group IIIB metal alkyl or alkyl metal halide wherein the alkyl group contains from about 1 to about 8 carbon atoms . 29. The alpha-olefin polymerization catalyst system of Claim 28 wherein the cocatalyst is triethylaluminum or triisobutylaluminum. *^. 30. The alpha-olefin polymerization catalyst system of Claim 26 wherein the cocatalyst is added in a molar ratio of about 1:1 to about 500:1 based on the transition metal compound of said catalyst. 31. The alpha-olefin polymerization catalyst 0 system of Claim 30 wherein the cocatalyst is added in a molar ratio of about 5:1 to about 200:1 based on the transition metal compound of said catalyst. 5 32. The alpha-olefin polymerization catalyst system of Claim 26 further comprising at least one cocatalyst modifier, activator or promoter. 33. The alpha-olefin polymerization catalyst system of Claim 32 wherein the cocatalyst modifier, activator or promoter is selected from the group consisting of halosilanes, halocarbons, aromatic esters, organometallic compounds and alkoxysilanes. 34. The alpha-olefin polymerization catalyst system of Claim 33 * wherein the cocatalyst modifier, activator or promoter is selected from the group consisting of carbon tetrachloride, carbon tetrabromide, dichloromethane, dibromomethane, 1, 1, 1-trichloroethane, chloroflurocarbons, hydro-chlorofluorocarbons, silicon tetrachloride, trichlorosilane, dichlorosilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, phenyltriethoxysilane and cyclohexyltrimethoxysilane . 35. A process for (co)polymerizing α-olefins comprising polymerizing at least one C 2 -C B α-olefin under polymerization conditions in the presence of the polymerization catalyst system of Claim 26, wherein the cocatalyst is added in a molar ratio of about 1:1 to about 500:1 based on the transition metal compound of said catalyst . 36. The process of Claim 35 wherein said a- olefin is (co)polymerized into a polymer or copolymer having substantially spherical particles whose median particle size ranges from about 10 to about 5000 microns.

Inventors: DIMAIO ANTHONY-J, MEVERDEN CRAIG C, DIMAIO, ANTHONY-J., MEVERDEN, CRAIG, C.
Applicants: QUANTUM CHEM CORP, QUANTUM CHEMICAL CORPORATION
Application year: 1996
Main classification: B01J103
IPC codes: B01J31, C08F4, C08F10