NO169015B - SUPPORTED OLEPHINE POLYMERIZATION CATALYST, PROCEDURE FOR PREPARING THEREOF AND PROCEDURE FOR PREPARING POLYMERS OF ETHYLENE AND COPOLYMERS OF ETHYLENE AND ALFA-OLEFINES OR DI-OLEFINES - Google Patents

Abstract

A process is described for the polymerisation of olefins in which a supported catalyst is used, which catalyst comprises a support and the product of the reaction of a metallocene of a metal in group 4b of the periodic table and an alumoxane, forming the product of the said reaction in the presence of the support.

Description

The present invention relates to a supported olefin polymerization catalyst, a method for producing this and a method for producing polymers of ethylene and copolymers of ethylene and oc-olefins or -di-olefins.

Traditionally, ethylene and 1-olefins have been polymerized or copolymerized in the presence of hydrocarbon-insoluble catalyst systems including a transition metal compound and an aluminum alkyl. Recently, it has been found that active homogeneous catalyst systems including a bis(cyclopentadienyl)titanium dialkyl or a bis(cyclopentadienyl)zirconium dialkyl, an aluminum trialkyl and water are useful for the polymerization of ethylene. Such catalyst systems are generally referred to as "Ziegler-type catalysts".

DE Patent Publication No. 2,608,863 describes the use of a catalyst system for the polymerization of ethylene consisting of bis(cyclopentadienyl)titanium dialkyl, aluminum trialkyl and water.

DE Patent Publication No. 2,608,933 describes an ethylene polymerization catalyst system consisting of zirconium metallocenes of the general formula (cyclopentadienyl)-nZrY4_n, where n represents a number in the range of 1 to 4, Y represents R, CH2A1R2, CH2CH2A1R2 and CH2CH(Å1R2)2, where R stands for alkyl or metalloalkyl and an aluminum trialkyl cocatalyst and water.

European Patent Publication No. 0035242 describes a process for the preparation of ethylene and atactic propylene polymers in the presence of a halogen-free Ziegler catalyst system from (1) cyclopentadienyl compound of the formula (cyclopentadienyl)nMeY4_n where n is an integer from 1 to 4, Me is a transition metal , especially zirconium, and Y is either hydrogen, a C^-Cs alkyl or metal alkyl group or a residue having the following general formula CH2A1R2, CH2CH2A1R2 and CH2CH(A1R2)2 in which R stands for a C^-Cs alkyl or metal alkyl group, and (2) an alumoxane.

Additional descriptions of homogeneous catalyst systems including a metallocene and alumoxane are found in European Patent Publication No. 0069951 and U.S. Pat. Patent No. 4,404,344.

An advantage of the metallocene-alumoxane homogeneous catalyst system is the very high activity achieved for ethylene polymerization. Another significant advantage is that unlike olefin polymers prepared in the presence of conventional heterogeneous Ziegler catalysts, terminal unsaturation is present in polymers prepared in the presence of these homogeneous catalysts. Nevertheless, the catalysts have a disadvantage, which is that the ratio between alumoxane and metallocene is high, e.g. of the order of 1000 to 1 or higher. Such voluminous amounts of alumoxane would require extensive processing of the resulting polymer product to remove the unwanted aluminum. Another disadvantage of the homogeneous catalyst system, which is also associated with the traditional heterogeneous Ziegler catalysts, is the multiple delivery systems required to introduce the individual catalyst components into the polymerization reactor.

It is therefore highly desirable to provide a metallocene-based catalyst that is commercially useful for the polymerization of olefins in which the ratio of aluminum to transition metal is within acceptable ranges and further to provide a polymerization catalyst that does not require the presence of a cocatalyst, so that the number of delivery systems for the introduction of catalyst into the polymerization reactor is reduced.

The present invention provides a supported olefin polymerization catalyst which is characterized in that it includes the supported reaction product of at least one metallocene of a metal from group 4b in the periodic table and an alumoxane, where the molar ratio between aluminum and transition metal is in the range of 100:1 to 1:1 , where the product is formed in the presence of the carrier, and where the metallocene is used in an amount of 0.01 to 10 mmol per gram carries.

The supported reaction product will polymerize olefins at commercially acceptable rates without the presence of the unwanted excess of alumoxane required in the homogeneous system.

The present invention further provides a method for producing a supported olefin polymerization catalyst including the supported reaction product of at least one metallocene of a metal from group 4b in the periodic table and an alumoxane, where the molar ratio between aluminum and transition metal is in the range of 100:1 to 1:1. The method is characterized in that it includes the addition to a slurry of the carrier in an inert hydrocarbon solvent, of an alumoxane in an inert hydrocarbon solvent and the metallocene in an amount of from 0.001 to 10 mmol metallocene per gram carries.

The invention further relates to a method for the production of polymers of ethylene and copolymers of ethylene and α-olefins or di-olefins, which is characterized in that it includes the polymerization being effected in the presence of a supported catalyst comprising the supported reaction product of at least one metallocene of a metal from group 4b of the periodic table and an alumoxane, where the aluminum to transition metal molar ratio is in the range of 100:1 to 1:1, where the product is formed in the presence of the support, and where the metallocene is used in an amount of 0.01 to 10 mmol per gram carries.

The metallocenes used in the preparation of the reaction product on the support are organometallic coordination compounds which are cyclopentadienyl derivatives of a group 4b metal from the Periodic Table (56th edition of "Handbook of Chemistry and Physics", CRC Press ]1976§) and include mono-, di- and tricyclopentadienyls and their derivatives of the transition metals. Particularly desirable is the metallocene of a metal, such as titanium, zirconium, hafnium and vanadium. The alumoxanes used in the preparation of the reaction product with the metallocenes are themselves the reaction products between an aluminum trialkyl and water.

The alumoxanes are well known in the art and include oligomeric, linear and/cyclic alkylalumoxanes represented by the formula: for oligomeric, linear alumoxanes and

for oligomeric, cyclic alumoxane

wherein n is 1-40, preferably 10-20, m is 3-40, preferably 3-20 and R is a C 1 -C 8 alkyl group and preferably methyl. In general, when producing alumoxanes from e.g. aluminum trimethyl and water, a mixture of linear and cyclic compounds.

The alumoxanes can be produced in a number of ways. Preferably, they are prepared by bringing water into contact with a solution of aluminum trialkyl, which e.g. aluminum trimethyl, in a suitable organic solvent such as benzene or an aliphatic hydrocarbon. E.g. aluminum alkyl is treated with water in the form of a moist solvent. In a preferred method, aluminum alkyl, such as aluminum trimethyl, can be brought into contact with a hydrated salt such as hydrated ferrous sulfate. The method includes treatment of a dilute solution of aluminum trimethyl, in e.g. toluene, with ferrous sulfate heptahydrate.

Briefly stated, the transition metal-containing catalyst according to the present invention is obtained by reacting an alumoxane and a metallocene in the presence of a solid support material. The supported reaction product can be used as the sole catalyst component for the polymerization of olefins or it can alternatively be used with an organometallic cocatalyst.

The carrier can typically be any solid, especially porous carrier such as talc, inorganic oxides and resinous carrier material such as polyolefin. Preferably, the carrier material is an inorganic oxide in finely divided form.

Suitable inorganic oxide materials which are advantageously used in the present invention include group 2a, 3a, 4a or 4b metal oxides, such as silicon oxide, aluminum oxide, and silicon oxide-alumina and mixtures thereof. Other inorganic oxides that can be used either alone or together with silicon oxide, aluminum oxide or silicon oxide-aluminum oxide are magnesium oxide, titanium oxide, zirconium oxide and the like. However, other suitable carrier materials can be used, e.g. finely divided polyolefins, such as finely divided polyethylene.

The metal oxides generally contain acidic surface hydroxyl groups that will react with the alumoxane or transition metal compound that is first added to the reaction solvent. Before use, the inorganic oxide carrier is dehydrated, i.e. subjected to a heat treatment to remove water and reduce the concentration of surface hydroxyl groups. The treatment is carried out in vacuum or under purging with a dry inert gas, such as nitrogen, at a temperature of 100°C to 1000°C, and preferably from 300°C to 800°C. The pressure is not critical. The duration of the heat treatment can be from 1 to 24 hours. However, shorter or longer times may be used provided equilibrium is established with the surface hydroxyl groups.

Chemical dehydration as an alternative method for dehydrating metal oxide carrier material can be advantageously used. Chemical dehydration converts all water and hydroxyl groups on the oxide surface into inert species. Useful chemical agents are e.g. S1C14; chlorosilanes, such as trimethylchlorosilane, dimethylaminotrimethylsilane, etc. The chemical dehydration is achieved by slurping the inorganic particulate material, such as e.g. silicon oxide in an inert, low-boiling hydrocarbon, such as e.g. hexane. During the chemical dehydration reaction, the silicon oxide should be kept in a moisture- and oxygen-free atmosphere. A low-boiling, inert hydrocarbon solution of the chemical dehydrating agent, such as e.g. dichlorodimethylsilane. The solution is slowly added to the slurry. The temperature ranges during the chemical dehydration reaction can be from 25° C to 120° C, however, higher and lower temperatures can be used. Preferably the temperature is 50°C to 70°C. The chemical dehydration process should be allowed to proceed until all the moisture has been removed from the particulate carrier material, this is observed when gas evolution ceases. Normally, the chemical dehydration reaction is allowed to proceed from 30 minutes to 16 hours, preferably 1 to 5 hours. At the end of the chemical dehydration, the solid particulate material is filtered under a nitrogen atmosphere and washed one or more times with a dry, oxygen-free, inert hydrocarbon solvent. The washing solvents, as well as the diluents used to prepare the slurry and dissolve the chemical dehydrating agent, can be any suitable inert hydrocarbon. Examples of such hydrocarbons are heptane, hexane, toluene, isopentane etc.

The normally hydrocarbon-soluble metallocenes and alumoxanes are converted into a heterogeneously supported catalyst by depositing said metallocenes and alumoxanes on the dehydrated support material. The order of addition of the metallocene and alumoxane to the support may vary. For example, the metallocene (pure or dissolved in a suitable hydrocarbon solvent) may first be added to the support material followed by addition of the alumoxane; - the alumoxane and the metallocene can be added to the support material at the same time; the alumoxane may first be added to the support material followed by addition of the metallocene. In an advantageous embodiment of the present invention, the alumoxane dissolved in a suitable inert hydrocarbon solvent is added to the carrier material suspended in the same or another suitable hydrocarbon liquid, and then the metallocene is added to the slurry.

The treatment of the carrier material, discussed above, is carried out in an inert solvent. The same inert solvent or another inert solvent is also used to dissolve the metallocenes and alumoxanes. Preferred solvents include mineral oils and the various hydrocarbons which are liquid at the reaction temperature and in which the individual components are soluble. Examples of useful solvents include the alkanes, such as pentane, iso-pentane, hexane, heptane, octane and nonane; cycloalkanes such as cyclopentane and cyclohexane; and aromatic compounds such as benzene, toluene, ethylbenzene and diethylbenzene. Preferably, the carrier material is slurried in toluene and the metallocene and alumoxane are dissolved in toluene before addition to the carrier material. The amount of solvent used is not critical. Nevertheless, the amount used should be such that it provides satisfactory heat transfer away from the catalyst components during the reaction and allows good mixing.

The supported catalyst according to the present invention is prepared as mentioned by adding the reactants in the suitable solvent and preferably toluene to the slurry of the carrier material, preferably silicon oxide slurry in toluene. The ingredients can be added to the reaction vessel quickly or slowly. The temperature maintained during the contact step between the reactants can vary within wide limits, e.g. from 0° to 100°C. Higher or lower temperatures can also be used. Preferably, the alumoxanes and metallocenes are added to the silicon oxide at room temperature. The reaction between the alumoxane and the carrier material is rapid, however, it is desirable that the alumoxane is kept in contact with the carrier material from 1 hour to 18 hours or longer. Preferably, the reaction is maintained for approx. 1 hour. The reaction between the alumoxane, the metallocene and the support material can be observed due to its exothermic nature and a color change.

At all times, the individual components, as well as the recovered catalyst component, are protected against oxygen and moisture. Therefore, the reactions must be carried out in an oxygen- and moisture-free atmosphere and the product extracted in an oxygen- and moisture-free atomosphere. The reactions are therefore preferably carried out in the presence of an inert dry gas, such as e.g. nitrogen. The recovered solid catalyst is kept in a nitrogen atmosphere.

Upon completion of the reaction between the metallocene and the alumoxane and the support, the solid material can be recovered by any known technique. E.g. the solid material can be recovered from the liquid by vacuum evaporation or decantation. The solid is then dried under a stream of pure, dry nitrogen or dried under vacuum.

The amount of alumoxane and metallocene which is advantageously used in the production of the solid supported catalyst component can vary within a wide range. The concentration of the alumoxane added to the substantially dry carrier may be in the range of 0.1 to 10 millimoles/g carrier, however, larger or smaller amounts may be advantageously used. Preferably, the alumoxane concentration is in the range from 0.5 to 10 millimol/g carrier and in particular 1 to 5 millimol/g carrier. The amount of metallocene added will be such that a molar ratio between aluminum and transition metal from 1:1 to 100:1 is provided. Preferably, ratios are in the range from 5:1 to 50:1, and more preferably in the range from 10:1 to 20:1. These conditions are significantly lower than those required for the homogeneous system.

In the present invention, at least one metallocene compound is used in the production of the supported catalyst. The metallocene, i.e. a cyclopentadienylide, is a metal derivative of a cyclopentadiene. The metallocenes which are usually used in the present invention contain at least one cyclopentadiene ring. The metal is selected from group 4b metals, and is preferably titanium, zirconium, hafnium, chromium and vanadium, and especially titanium and zirconium. The cyclopentadienyl ring can be unsubstituted or contain substituents, such as e.g. a hydrocarbyl substituent. The metallocene may contain one, two or three cyclopentadienyl rings, however two rings are preferred.

The preferred metallocenes can be represented by the general formulas: wherein Cp is a cyclopentadienyl ring, M is a 4b transition metal, R is a hydrocarbyl group or hydrocarboxy containing from 1 to 20 carbon atoms, X is a halogen, and m = 1-3, n = 0 -3, q = 0-3 and the sum of m+n+q will be equal to the oxidation state of the metal.

wherein (CsR'^) is a cyclopentadienyl or substituted cyclopentadienyl, where R' are the same or different and stand for hydrogen or a hydrocarbyl radical such as an alkyl, alkenyl, aryl, alkylaryl, or arylalkyl radical containing from 1 to 20 carbon atoms or 2 carbon atoms are joined to a C4-C£ ring, R'' is a C^-C4 alkylene residue, a dialkylgermanium or silicon, or an alkylphosphine or

amine residue bridging two (CsR^J rings, Q is a hydrocarbyl residue such as aryl, alkyl, alkenyl, alkylaryl, or arylalkyl residue containing 1-20 carbon atoms, hydrocarboxy residue containing 1-20 carbon atoms or halogen, and may be the same or different from each other, Q' is an alkylidene residue containing from 1 to 20 carbon atoms, s is 0 or 1, g is 0, 1 or 2, s is 0 when g is 0, k is 4 when s is 1 and k is 5 when s is 0, and M is as defined above.

Examples of hydrocarbyl residues are methyl, ethyl, propyl, butyl, amyl, isoamyl, hexyl, isobutyl, heptyl, octyl, nonyl, decyl, cetyl, 2-ethylhexyl, phenyl etc.

Examples of halogen atoms include chlorine, bromine, fluorine and iodine, and of these halogen atoms chlorine is preferred.

Examples of hydrocarboxylic acid residues are methoxy, ethyloxy, propoxy, butoxy, amyloxy etc.

Examples of allylidene residues are methylidene, ethylidene and propylidene.

Illustrative examples of the metallocenes indicated by formula I are dialkyl metallocenes such as bis(cyclopentadienyl)titanium dimethyl, bis(cyclopentadienyl)titanium diphenyl, bis(cyclopentadienyl)zirconium dimethyl, bis(cyclopentadienyl)zirconium diphenyl, bis(cyclopentadienyl)hafniumdimethyl and -diphenyl, bis( cyclopentadienyl)titanium di-neopentyl, bis(cyclopentadienyl)zirconium di-neopentyl, bis(cyclopentadienyl)titandibenzyl, bis(cyclopentadienyl)zirconium dibenzyl, bis(cyclopentadienyl)vanadiumdimethyl; the monoalkyl metallocenes such as bis(cyclopentadienyl)titanium methyl chloride, bis(cyclopentadienyl)titanium ethyl chloride, bis(cyclopentadienyl)titanium phenyl chloride, bis(cyclopentadienyl)zirconium methyl chloride, bis(cyclopentadienyl)zirconium methyl chloride, bis(cyclopentadienyl)zirconium phenyl chloride, bis(cyclopentadienyl)titanium methyl bromide, bis-( cyclopentadienyl)methyl iodide, bis(cyclopentadienyl)titanethyl bromide, bis(cyclopentadienyl)titanium ethyl iodide, bis(cyclopentadienyl)titanium phenyl bromide, bis(cyclopentadienyl)titanium phenyl iodide, bis(cyclopentadienyl)zirconium methyl bromide, bis-(cyclopentadienyl)zirconium methyl iodide, bis(cyclopentadienyl)- zirconium methyl bromide, bis(cyclopentadienyl)zirconium methyliodide, bis(cyclopentadienyl)zirconiumphenylbromide, bis(cyclopentadienyl)zirconium\imphenyliodide; the trialkyl metallocenes such as cyclopentadienyltitaniumtrimethyl, cyclopentadienylzirconiumtriphenyl and cyclopentadienylzirconium tripentyl, cyclopentadienylzirconiumtrimethyl, cyclopentadienylhafniumtriphenyl, cyclopentadienylhafnium tripentyl and cyclopentadienylhafniumtrimethyl.

Illustrative examples of II and II metallocenes which can be advantageously used in the present invention are mono-cyclopentadienyl titanocenes such as pentamethylcyclopentadienyl titanium trichloride, pentaethylcyclopentadienyl titanium trichloride, bis(pentamethylcyclopentadienyl)titanium diphenyl, carbene, represented by the formula bis(cyclopentadienyl)titanium=CH2 and derivatives of this reagent such as bls(cyclopentadienyl)-T1=CH2•A1(CH3)3, (Cp2TiCH2)2, Cp2TiCH2CH(CH3)CH2, Cp2Ti-CHCH2CH2; substituted bis(cyclopentadienyl)titanium(IV) compounds, such as: bis(indenyl)titanium diphenyl or dichloride, bis(methylcyclopentadienyl)titanium diphenyl or dihalides; dialkyl, trialkyl, tetraalkyl and pentaalkylcyclopentadienyltitanium compounds, such as bis(1,2-dimethylcyclopentadienyl)titanium diphenyl or dichloride, bis(1,2-diethylcyclopentadienyl)titanium diphenyl or dichloride and other dihalide complexes; silicon-, phosphine-, amine- or carbon-bridged cyclopentadiene complexes, such as dimethylsilyldicyclopentadienyltitanium diphenyl or -dichloride, methylphosphinedicyclopentadienyltitanium diphenyl or -dichloride, methylenedicyclopentadienyltitanium diphenyl or -dichloride and other dihalide complexes and the like.

Illustrative examples of the zirconocenes of the formulas II and III which can be advantageously used in the present invention are pentamethylcyclopentadienylzirconium trichloride, pentaethylcyclopentadienylzirconium trichloride, bis(pentamethylcyclopentadienyl)zirconium diphenyl, the alkyl-substituted cyclopentadienes, such as bis(ethylcyclopentadienyl)zirconium dimethyl, bis(< p->phenylpropylcyclopentadienyl)zirconiumdimethyl, bis-(methylcyclopentadienyl)zirconiumdimethyl, bis(n-butyl-cyclopentadienyl)zirconiumdimethyl, bis(cyclohexylmethyl-cyclopentadienyl)zirconiumdimethyl, bis(n-octyl-cyclopentadienyl)zirconiumdimethyl, and haloalkyl and dihalide complexes of the above; dialkyl, tri-alkyl, tetra-alkyl and penta-alkyl cyclopentadienes, such as bis(pentamethylcyclopentadienyl)zirconiumdimethyl, bis(1,2-dimethylcyclopentadienyl)zirconiumdimethyl and the dihalide complexes of the above; silicon-, phosphorus- and carbon-bridged cyclopentadiene complexes such as dimethylsilyldicyclopentadienylzirconium dimethyl or -dihalide, and methylenecyclopentadienylzirconium dimethyl or -dihalide, and methylenecyclopentadienylzirconium dimethyl or -dihalide, carbenes represented by the formula Cp2Zr=CHP(C5H5)2CH3, and derivatives of these compounds, such as Cp2ZrCH2CH(CH3)CH2.

Bis(cyclopentadienyl)hafnium dichloride, bis(cyclopentadienyl)hafnium dimethyl, bis(cyclopentadienyl)vanadium dichloride, etc. are examples of other metallocenes.

The inorganic oxide support used in the preparation of the catalyst may be any particulate oxide or mixed oxide as described above which has been thermally or chemically dehydrated so that it is substantially free of absorbed moisture.

The specific properties such as particle size, surface area, pore volume and number of surface hydroxyl groups for the inorganic oxide are not critical for its applicability in carrying out the invention. Since such properties, however, determine the amount of the inorganic oxide that it is desirable to use in the preparation of the catalyst compositions, as well as affecting the properties of the polymer produced by means of the catalyst compositions, these properties must often be taken into account when choosing an organic oxide for application of a particular feature of the invention. When e.g. the catalyst composition is to be used in a gas-phase polymerization process, a type of process in which it is known that the polymer particle size can be varied by varying the particle size in the carrier, the inorganic oxide used in the preparation of the catalyst composition should be an oxide that has a particle size that is suitable for the production of a polymer having the desired particle size. In general, optimum results are usually obtained by using inorganic oxides having an average particle size in the range of 30 to 600 micrometers, preferably 30 to 100 micrometers; a surface area of 50 to 1000 m<2> per gram, preferably 100 to 400 m<2> per gram; and a pore volume of 0.5 to 3 cm^ per gram; preferably 0.5 to 2 cm^ per gram.

The polymerization can be carried out by a solution, slurry or gas phase technique, generally at a temperature in the range of 0-160°C or higher, and at atmospheric pressure, sub-atmospheric pressure or above atmospheric pressure; and conventional polymerization aids, such as hydrogen, can be used if this is desired. It is generally preferred to use the catalyst preparations at a concentration so as to provide 0.000001-0.005*, most preferably 0.00001-0.0003 weight-* of transition metal, based on the weight of the monomer(s), in the polymerization of ethylene , alone or with one or more higher olefins.

In a slurry polymerization process, pressure above or below atmospheric pressure and temperatures in the range 40-110°C can be used. In a slurry polymerization, a suspension of solid, particulate polymer is formed in a liquid polymerization medium to which ethylene, α-olefin comonomer, hydrogen and catalyst are added. The liquid used as polymerization medium can be an alkane or cycloalkane, such as butane, pentane, hexane or cyclohexane, or an aromatic hydrocarbon, such as toluene, ethylbenzene or xylene. The medium used should be liquid under the polymerization conditions and relatively inert. Preferably, hexane or toluene is used.

In a gas-phase polymerization process, pressure above atmospheric pressure and temperatures in the range 50-120'C are used. Gas phase polymerization can be carried out in a stirred or fluidized bed of catalyst and product particles in a pressure tank, designed to allow separation of product particles from unreacted gases. Thermostatically treated ethylene, comonomer, hydrogen and an inert, diluting gas such as nitrogen can be introduced or recycled to maintain the particles at a temperature of 50-120°C. Triethyl aluminum can, if necessary, be added as a cleaning agent for water, oxygen and other possible contaminants. Polymeric product can be removed continuously or semi-continuously at such a rate that a constant amount of product is maintained in the reactor. After polymerization and deactivation of the catalyst, the product polymer can be recovered by any suitable method. In a commercial embodiment, the polymer product can be extracted directly from the gas-phase reactor, cleaned of remaining monomer by a nitrogen purge, and used further without deactivation or catalyst removal. The polymer obtained can be extruded in water and cut into pellets or other suitable finely divided forms. Pigments, antioxidants and other additives known in the art can be added to the polymer.

The molecular weight of the polymer product obtained according to the present invention can vary within a wide range, from as low as 500 up to 2,000,000 or higher, and preferably from 1,000 to 500,000.

For the production of polymeric product which has a narrow molecular weight distribution, it is preferred to deposit only one metallocene on the inert, porous support material, and to use said supported metallocene together with the alumoxane as polymerization catalyst.

For many purposes, such as e.g. extrusion and casting processes, it is desirable to produce polyethylene which has a broad molecular weight distribution of the unimodal and/multimodal type. Such polyethylenes have excellent processability, i.e. they can be processed at a higher throughput speed with lower energy consumption and at the same time such polymers will show reduced melt flow perturbations. Such polyethylenes can be obtained by providing a catalyst component comprising at least two different metallocenes, both of which have different propagation and termination rate constants for ethylene polymerization. Such rate constants can be readily determined by one of ordinary skill in the art.

The molar ratio between the metallocenes, which e.g. between a zirconocene and a titanocene in such catalysts can vary over a wide range, and the only limitation on the molar ratio is the width of the Mw distribution or the degree of bimodality desired in the product polymer. It is desirable that the metallocene to metallocene molar ratio is 1:100 to 100:1, and preferably 1:10 to 10:1.

Based on the present invention, (co)polyolefin reactor mixtures including polyethylene and copolyethylene-α-olefins can be produced. The reactor mixtures are obtained directly during a single polymerization process, i.e. the mixtures are obtained in a single reactor by simultaneous polymerization of ethylene and copolymerization of ethylene with an α-olefin, thereby eliminating expensive mixing operations. The method for producing reactor mixtures can be used together with other previously known mixing techniques, e.g. the reactor mixtures produced in a first reactor can be subjected to further mixing in a second step using the series reactors.

To prepare reactor mixtures, the supported metallocene catalyst component includes at least two different metallocenes both having different comonomer reactivity ratios.

Comonomer reactivity ratios for the metallocenes can generally be found by well-known methods, such as e.g. described in "Linear Method for Determining Monomer Reactivity Ratios in Copolymerization", M. Fineman and S. D. Ross, J. Polymer Science 5, 259 (1950) or "Copolymerization", F. R. Mayo and C. Walling, Chem. Fox. 46, 191 (1950) which is incorporated herein by reference. To determine reactivity ratios, e.g. the most widely used copolymerization model based on the following equations:

where Mi stands for a monomer molecule randomly denoted i (where i = 1.2) and Mj<*> stands for a growing polymer chain to which the monomer i is most recently attached, the k-^-j values are the rate constants for the specified reactions. In this case, k]^ represents the rate at which an ethylene unit is introduced into a growing polymer chain in which the previous introduced monomer unit was also ethylene. Reactivity ratio is obtained as: r1=k11/<k>12 °g r2=k22/<k>21

where ku, k^, k22 °S k21 are the rate constants for ethylene (1) or comonomer (2) addition to a catalyst site where the last polymerized monomer is ethylene (k^x) or comonomer (2) (k2x)«

Since, according to the present invention, a polymer product with high viscosity can be produced at a relatively high temperature, the temperature does not constitute a limiting parameter as with previously known metallocene/alumoxane catalysts. The catalyst systems described above are therefore suitable for the polymerization of olefins by solution, slurry or gas phase polymerizations over a wide range of temperature and pressure. E.g. such temperatures can lie in the range from -60°C to 280°C, and especially in the range from 0°C to 160*C. The pressures used in the method according to the present invention are the well-known pressures, e.g. in the range of 1 to 500 atmospheres, however, higher pressures may be used.

The polymers produced by the method according to the present invention can be used for the production of a wide range of articles, as is known for homopolymers of ethylene and copolymers of ethylene and higher cx-olefins.

In a slurry phase polymerization, the alkyl aluminum cleaning agent is preferably dissolved in a suitable solvent, typically in an inert hydrocarbon solvent, such as toluene, xylene and the like. in a molar concentration of approx. 5x10" However, larger or smaller quantities may be used.

In the following, the present invention will be explained in more detail by means of examples.

EXAMPLES

In the examples that follow, the alumoxane used was prepared by adding 76.5 g of ferrous sulfate heptahydrate in 4 equal portions over a 2 hour period to a rapidly stirred 2 liter round bottom flask containing 1 liter of a 13.1 wt.* solution of trimethyl aluminum (TMA) in toluene. The flask was kept at 50°C under a nitrogen atmosphere. The methane formed was continuously vented. At the end of the addition of ferrous sulfate heptahydrate, the flask was continuously stirred and kept at a temperature of 50<*>C for 6 hours. The reaction mixture was cooled to room temperature and The clear solution containing the alumoxane was separated by decantation from the insoluble solids.

Molecular weights were determined on a "Water's Associates Model No. 150C GPC" (gel permeation chromatography). The measurements were obtained by dissolving polymer samples in hot trichlorobenzene and filtering. The GPC experiments were performed at 145°C in trichlorobenzene at a flow rate of 1.0 mL/min using styragel columns from Perkin Eimer, Inc. 3.1* solutions (300 microliters of trichlorobenzene solution) were injected and the duplicate experiments The integration parameters were obtained using a Hewlett-Packard Data Module.

Catalvsator manufacturing

Catalyst A

10 g of high surface area silica ("Davison 952"), dehydrated in a stream of dry nitrogen at 800°C for 5 hours, was slurried with 50 cm<3> toluene at 25°C under nitrogen in a 250 cm< 3> round bottom flask using a magnetic stirrer. 25 cm<3> methylalumoxane in toluene (1.03 mol/liter in aluminum) was added dropwise to the silica slurry over 5 minutes with continuous stirring. Stirring was continued for 30 minutes while maintaining the temperature at 25° C., after which the toluene was decanted off and the solids recovered. To the alumoxane-treated silicon oxide, 25 cm<3> of a toluene solution was added dropwise over the course of 5 minutes and with constant stirring containing 0.200 g of dicyclopentadienylzirconium dichloride. The slurry was stirred for an additional 1/2 hour while maintaining the temperature at 25°C, and then the toluene was decanted and the solids recovered and dried in vacuo for 4 hours. The recovered solid was wh rken soluble or extractable in hexane. Analysis of the catalyst showed that it contained 4.5 wt-* aluminum and 0.63 wt-* zirconium.

Catalyst B

The present catalyst shall demonstrate that the use of the catalyst according to the invention in the production of copolyethylene with 1-butene results in more effective incorporation of 1-butene, which is evident from the density of the polymer product.

The procedure for the preparation of catalyst A was followed, with the exception that the methylalumoxane treatment of the carrier material was omitted. Analysis of the recovered solid showed that it contained 0.63 wt-* zirconium and 0 wt-* aluminium.

Catalyst C

The procedure for the preparation of catalyst A was followed, except that 0.300 g of bis(cyclopentadienyl)zirconium dimethyl was used instead of the bis(cyclopentadienyl)zirconium dichloride. Analysis of the recovered solid showed that it contained 4.2 wt-* aluminum and 1.1 wt-* zirconium.

Catalyst D

The procedure for the preparation of catalyst A was followed with the exception that 0.270 g of bis(n-butyl-cyclopentadienyl)zirconium dichloride was used instead of the bis(cyclopentadienyl)zirconium dichloride in catalyst A, and all steps were carried out at 80°C. Analysis of the recovered solid showed that it contained 0.61 wt-* zirconium and 4.3 wt-* aluminium.

Catalyst E

The procedure for the preparation of catalyst D was followed, with the exception that 0.250 g of bis(n-butyl-cyclopentadienyl) zirconium dimethyl was used instead of the metallocene dichloride. Analysis of the recovered solid showed that it contained 0.63 wt-* zirconium and 4.2 wt-* aluminium.

Catalyst F

The procedure for the preparation of catalyst D was followed, with the exception that 0.500 g of bis(pentamethylcyclopentadienyl)zirconium dichloride was used instead of the methoallocene. Analysis of a recovered solid showed that it contained 0.65 wt-* zirconium and 4.7 wt-* aluminium.

Example 1 polymer in sas. l on catalyst A

Polymerization was carried out in the gas phase in a 1-liter autoclave reactor equipped with a paddle stirrer, an outer water jacket for temperature control, a partitioned inlet, and a controlled supply of dry nitrogen, ethylene, hydrogen, and 1-butene. The reactor, containing 40.0 g of ground polystyrene (10 mesh) which had been added to facilitate agitation in the gas phase, was dried and carefully degassed at 85°C. As a cleaning agent, 2.00 cm<3> methylalumoxane solution (0.64 mol total aluminum) was injected through the inlet into the container using a gas-tight syringe to remove traces of oxygen and water. The reactor contents were stirred at 120 rpm at 85°C for 1 minute at a nitrogen pressure of 101.4 kPa. 500.0 mg of catalyst A was injected into the reactor and the reactor was pressurized to 1480.4 kPa with ethylene. The polymerization was continued for 10 minutes while the reaction vessel was maintained at 85°C and at a pressure of 1480.4 kPa with constant ethylene flow. The reaction was stopped by rapid cooling and venting. 12.3 g of polyethylene was recovered. The polyethylene was recovered by stirring the product with 1 liter of dichloromethane at 40°C, filtering and washing with dichloromethane to recover the insoluble polyethylene product from the soluble polystyrene stirring aid. The polyethylene had a molecular weight of 146,000.

Example 2 polymer in sas. 1 on catalyst A

The polymerization was carried out as in example 1 in the presence of catalyst A, except that 122.0 kPa of hydrogen was placed in the reactor before the ethylene injection. 13.2 g of polyethylene with a molecular weight of 29,000 was recovered.

Example 3 polymerization catalyst A

Polymerization was carried out as in Example 1 in the presence of catalyst A, except that 13.0 cm<3> (0.137 mol) of 1-butene was pressurized in the reactor together with the ethylene after the catalyst injection. 13.8 g of polyethylene with a molecular weight of 39,000 and a density of 0.918 g/cm<3> was recovered.

Comparative example 3A polymerization catalyst B The polymerization was carried out as in example 1 with the exception that catalyst B was used instead of catalyst A. 17.3 g of polyethylene with a molecular weight of 67,000 and a density of 0.935 g/cm<3> was recovered. The higher density compared to the density obtained in Example 3 demonstrates the less efficient incorporation of comonomers.

Example 4 polymer! sass. 1 on catalyst C

The polymerization was carried out as in example 1 with the exception that catalyst C was used instead of catalyst A. 9.8 g of polyethylene with a molecular weight of 189,000 and a density of 0.960 g/cm<3> was recovered.

Example 5 polymerization catalyst C

The polymerization was carried out as in Example 4, except that 13.0 cm<3> 1-butene (0.123 moles) and 105.5 kPa hydrogen (1.66 millimoles) were introduced after the catalyst along with the ethylene. 6.5 g of polyethylene with a molecular weight of 41,000 and a density of 0.926 g/cm<3> were recovered.

Example 6 polymerization catalyst C

The polymerization was carried out as in Example 4 except that the cleaning agent methylalumoxane was eliminated and no other aluminum alkyl cleaning agent was injected. 10.2 g of polyethylene with a molecular weight of 120,000 and a density of 0.960 g/cm<3> were recovered.

Example 7 polymer in sas. 1 on catalyst D

The polymerization was carried out as in Example 1, with the exception that 0.6 cm<3> of 25 wt* triethyl aluminum in hexane was used instead of the methylalumoxane solution according to Example 1, and catalyst D was used instead of catalyst A. 50.4 g were recovered polyethylene with a molecular weight of 196,000 and a density of 0.958 g/cm<3>.

Example 8 polymer! sass. 1 on catalyst D

The polymerization was carried out as in Example 1 with the exception that the cleaning agent, methylalumoxane, was omitted, catalyst D was used instead of catalyst A and the polymerization was stopped after 5 minutes. 28.8 g of polyethylene with a molecular weight of 196,000 and a density of 0.958 g/cm<3> were recovered.

Example 9 polymerization catalyst E

The polymerization was carried out as in example 8 by using catalyst E without any aluminum compound as a cleaning agent. 24.0 g of polyethylene was recovered with a weight average molecular weight of 190,000 and a number average molecular weight of 76,000 and a density of 0.958 g/cm<3>.

Example 10 polymerization catalyst F

The polymerization was carried out as in example 7 except that 0.500 g of catalyst F was used instead of catalyst D. 8.1 g of polyethylene with a molecular weight of 137,000 and a density of 0.960 g/cm<3> was recovered.

Claims (10)

1. Supported olefin polymerization catalyst, characterized in that it includes the supported reaction product of at least one metallocene of a metal from group 4b in the periodic table and an alumoxane, where the molar ratio between aluminum and transition metal is in the range of 100:1 to 1:1, where the product is formed in the presence of the carrier, and where the metallocene is used in an amount of 0.01 to 10 mmol per gram carries. 2. Supported olefin polymerization catalyst according to claim 1, characterized in that the support is a porous, inorganic metal oxide of a metal from group 2a, 3a, 4a or 4b. 3. Supported olefin polymerization ion catalyst according to claim 2, characterized in that the carrier is silicon oxide. 4. Supported olefin polymerization catalyst according to claim 1, characterized in that the metallocene is selected from titanium, zirconium and hafnium metallocenes and mixtures thereof. 5- Supported olefin polymerization catalyst according to claim 1, characterized in that the alumoxane is methylalumoxane. 6. Supported olefin polymerization catalyst according to claim 1, characterized in that the molar ratio lies in the range from 50:1 to 5:1. 7. Supported olefin polymerization catalyst according to claim 1, characterized in that the metallocenes are represented by the formulas (I) (Cp)mMRnXq (II) (C5R'k)gR"s(C5R'k)MQ3_3 and (III) R"s(C<5R> 'k)2M0' wherein Cp is a cyclopentadienyl ring, M is a transition metal from group 4b, R is a hydrocarbyl group or hydrocarboxy containing from 1 to 20 carbon atoms, X is a halogen, m = 1-3, n = 0-3, q = 0-3 and the sum of m + n + q is equal to the oxidation state of M, (C5R'k) is a cyclopentadienyl or substituted cyclopentadienyl, R' is the same or different and represents hydrogen or a hydrocarbyl residue selected from alkyl-, alkenyl-, aryl-, alkylaryl - or arylalkyl residues containing from 1 to 20 carbon atoms or 2 carbon atoms are joined so that a C^-C^ ring is formed, R'' is a Ci-C4~alkylene residue, a dialkylgermanium, a silicon, an alkylphosphine - or an amine residue that forms a bridge between two (C5R'k) rings, Q is a hydrocarbyl residue selected from aryl, alkyl, alkenyl, alkylaryl or arylalkyl residues containing 1-20 carbon atoms, or a hydrocarboxy residue containing 1-20 carbon atoms or halogen, and may be the same or different from each other, Q' is an alkylidene residue containing from 1 to 20 carbon atoms; s is 0 or 1; g is 0, 1 or 2; s is 0 when g is 0; k is 4 when s is 1 and k is 5 when s is 0. 8. Supported olefin polymerization catalyst according to claim 7, characterized in that the metallocenes are selected from bis(cyclopentadienyl)zirconium dichloride, bis(methylcyclopentadienyl)zirconium dichloride, bis(pentamethylcyclopentadienyl)zirconium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride and mixtures thereof. 9. Method for producing a supported olefin polymerization catalyst including the supported reaction product of at least one metallocene of a metal from group 4b in the periodic table and an alumoxane, where the molar ratio between aluminum and transition metal is in the range of 100:1 to 1:1, characterized in that the involves adding to a slurry of the carrier in an inert hydrocarbon solvent, an alumoxane in an inert hydrocarbon solvent and the metallocene in an amount of from 0.001 to 10 mmol metallocene per gram carries. 10. Process for the production of polymers of ethylene and copolymers of ethylene and α-olefins or di-olefins, characterized in that it includes the polymerization being effected in the presence of a supported catalyst comprising the supported reaction product of at least one metallocene of a metal from group 4b in the periodic table table and an alumoxane, where the aluminum to transition metal molar ratio is in the range of 100:1 to 1:1, where the product is formed in the presence of the carrier, and where the metallocene is used in an amount of 0.01 to 10 mmol per gram carries.