CS273318B2 - Method of catalyst preparation on a carrier for olefin polymerization - 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

(54)

(57) A process for preparing a supported olefin polymerization catalyst comprising silica, as a carrier and a reaction product of at least one zirconocene and methylalumoxane, wherein methylalumoxane and zirconocene are added to a slurry of silica in a hydrocarbon. The molar ratio of aluminum to zirconium ranges from 100: 1 to 1: 1 and the alumoxane is added to the carrier in an amount of from 0.1 to 10 mmol per gram of carrier.

CM co

CD r-H

ΓΛ fA r—

CM cn

CJ

CS 273 318 B2

The invention relates to a process for the preparation of a novel improved catalyst suitable for the polymerization and copolymerization of olefins, in particular for the polymerization of ethylene and copolymerization of ethylene with 1-olefins containing 3 or more carbon atoms, such as propylene, isobutene, 1-butene, 1-pentene, 1- hexene and 1-octene; dienes such as butadiene, 1,7-octadiene and 1,4-hexadiene; and cyclic olefins such as norbornene. In particular, the invention relates to a process for the preparation of a novel and improved heterogeneous transition metal-containing supported catalyst which can be used in olefin polymerization without the use of an organometallic cocatalyst. Also described herein is a process for polymerizing ethylene either alone or in admixture with other 1-olefins or diolefins in the presence of a new transition metal containing catalyst, which is the reaction product of zirconocene and alumoxane in the presence of a carrier such as silica.

Ethylene and 1-olefins are traditionally polymerized or copolymerized in the presence of hydrocarbon-insoluble catalyst systems containing transition metal compounds and alkyl aluminum. Recently, active homogeneous catalyst systems containing bis (cyclopentadienyl) titanium dialkyl or bis (cyclopentadienyl) zirconium dialkyl, trialkyl aluminum and water have been developed for ethylene polymerization. These catalyst systems are commonly referred to as Ziegler-type catalysts.

German Patent Application No. 2,608 B63 discloses the use of a catalytic system consisting of bis (cyclopentadienyl) titanium dialkyl, trialkyl aluminum and water for the polymerization of ethylene.

German Patent Application No. 2,608,933 discloses a catalyst system for ethylene polymerization consisting of zirconium metallocenes of the general formula (cyclopentadienyl) _n ZrY _{4 - n} wherein n represents a number ranging from 1 to 4,

Y represents R, CH ₂ AlR ₂ , CH ₂ CH ₂ AlR ₂ or CH ₂ CH (ALR ₂ ) ₂ and

R is alkyl or metalloalkyl, trialkylaluminum cocatalyst and water.

European Patent Application No. 0035242 discloses a process for the preparation of ethylene and atactic polypropylene polymers in the presence of a halogen-free Ziegler catalyst system consisting of:

(1) cyclopentadienyl compounds of general formula (cyclopentadienyl) _n MeY _{4 -n} , wherein n is an integer ranging from 1 to 4;

Me represents a transition metal, in particular zirconium and

Y is either hydrogen, (C 1 -C 5) alkyl or metalloalkyl or a radical of CH ₂ Al R ₂ , CH ₂ CH ₂ AIR ₂ or CH ₂ CH (Al R ₂ ) ₂ , wherein R is C 1 -C 5 alkyl, or metalloalkyl and

2) alumoxane.

Further references to sources describing homogeneous metallocene and alumoxane containing catalyst systems include European Patent Application No. 0069951 (Kaminsky et al.), U.S. Patent No. 4,404,344 (September 13, 1983, Sinn et al.) and US Patent Application Publication No. 697,308 (filed February 1, 1985); 501,588 (May 27, 1983), 728,111 (April 29, 1985), and 501,740 (June 6, 1983), all of which were transferred to Exxon Research and Engineering Company.

The advantage of homogeneous metallocene-alumoxane-based catalyst systems is great

CS 273 318 82 high ethylene polymerization activity. Another significant advantage is that the polymers produced in the presence of these homogeneous catalysts, in contrast to olefin polymers produced in the presence of conventional heterogeneous Ziegler catalysts, contain terminal unsaturation. However, these catalysts have the disadvantage that they have a high alumoxane to metallocene ratio of the order of, for example, 1000: 1 or higher. Such bulky amounts of alumoxane require thorough processing of the obtained polymer product to remove unwanted aluminum. A second disadvantage of the homogeneous catalyst system, which also has traditional heterogeneous Ziegler catalysts, is that the polymerization reactor must be equipped with a multiple feed system to introduce the individual components.

It would be highly desirable to provide a metallooene-based catalyst useful for industrial olefin polymerization, wherein the ratio of aluminum to transition metal is within a reasonable range, and the desirable properties of such a catalyst should furthermore not require the presence of a cocatalyst. The latter property would make it possible to reduce the number of feed systems for introducing the catalyst into the polymerization reactor.

SUMMARY OF THE INVENTION The present invention provides a process for preparing a supported olefin polymerization catalyst comprising silica, as a carrier and the reaction product of at least one zirconocene and methyl alumoxane, wherein methylalumoxane and zirconocene are added to the silicon dioxide slurry in a hydrocarbon. to the zirconium ranging from 100: 1 to 1: 1 and the alumoxane is added to the carrier in an amount of from 0.1 to 10 mmol per gram of carrier.

The carrier reaction product polymerizes olefins from an industrial point of view at an acceptable rate without requiring the presence of a disadvantageous excess of alumoxane, as in a homogeneous system.

The catalyst prepared by the process according to the invention is suitable for the polymerization of ethylene and other olefins and in particular for the production of ethylene homopolymers and ethylene copolymers with higher alpha-olefins and / or diolefins and / or cyclic olefins such as morborene.

The zirconiums used in the production of the carrier reaction product are organometallic coordination compounds. These are zirconium cyclopentadienyl derivatives and include mono-, di- and tricyclopentadienyl compounds and derivatives thereof. The methylalumoxane used in the preparation of the reaction product with zirconium is the reaction product of trimethyl aluminum with water.

Methylalumoxane is well known in the art and includes linear and / or cyclic products of formula (I)

R - Cal-0) _n - A1R ₂ (I)

R for oligomeric linear alumoxanes and formula II (II 1-O-). (II)

R in the case of oligomeric cyclic alumoxanes, wherein n represents a number of L to 40, preferably 10 to 20, m represents a number of 3 to 40, preferably 3 to 20, and

E is methyl. ,

Usually, in the preparation of methylalumoxane, from trimethyl aluminum and water, a mixture of linear and cyclic compounds is obtained.

Methylalumoxane can be prepared in various ways. Preferably, it is prepared by treating water with a solution of trimethyl aluminum in a suitable organic solvent such as benzene or benzene;

CS 273 318 82 aliphatic hydrocarbon. For example, trimethyl aluminum is treated with water as a wet solvent. In a preferred method, trimethyl aluminum is contacted with a hydrated salt such as hydrated ferrous sulfate. In this method, a dilute solution of trimethyl aluminum, for example in toluene, is treated with ferrous sulfate heptahydrate.

Catalyst containing: The transition metal of the present invention is obtained by reacting alumoxane and zirconocene in the presence of a solid support. The supported reaction product may be used as the sole olefin polymerization catalyst component or alternatively may be used in conjunction with an organometallic cocatalyst.

Silica is used as carrier in the process of the invention. The silica typically contains acidic surface hydroxyl groups that react with methylalumoxane or a transition metal compound upon first addition to the reaction solvent. Prior to use, the silica is dehydrated, i.e. subjected to a heat treatment to remove water therefrom and reduce the surface hydroxyl concentration. The treatment is carried out under vacuum or by purging the carrier with a dry inert gas, such as nitrogen, at a temperature of from about 100 to about 1000 ° C, and preferably from about 300 to about 800 ° C. The duration of the heat treatment may be from about 1 to about 24 hours. However, shorter or longer times may be used, provided that an equilibrium content of the surface hydroxyl groups is achieved.

As an alternative method of dehydrating the carrier silica, chemical dehydration may advantageously be used. In the chemical dehydration, all the water and the surface hydroxyl groups of the oxidic carrier are converted into inert substances. Suitable chemical reagents for this purpose are, for example, silicon tetrachloride, chlorosilanes such as trimethylchlorosilane, dimethylaminotrimethylsilane and the like. Chemical dehydration is carried out by suspending the particulate silica in an inert low boiling hydrocarbon such as hexane.

During the chemical dehydration reaction, the silica should be maintained in an atmosphere free of moisture and oxygen. A solution of a chemical dehydrating agent such as dichlorodimethylsilane in a low boiling inert hydrocarbon is then added to the silica slurry.

The solution is slowly added to the suspension. The temperature range during the chemical dehydration reaction may range from about 25 ° C to about 120 ° C, but may be operated at higher and lower temperatures. Preferably, the temperature is from about 50 to about 70 ° C. Chemical dehydration should be continued until all moisture has been removed from the particulate carrier, as evidenced by the interruption of gas evolution. Typically, the chemical dehydration reaction is allowed to proceed for from about 30 minutes to about 16 hours, preferably about 1 to 5 hours. After the chemical dehydration is complete, the particulate matter is filtered off under a nitrogen atmosphere and washed one or more times with a dry, inert, non-oxygen hydrocarbon solvent. Any suitable inert hydrocarbon may be used as the washing solvent and as the diluent to form a suspension and solution of the chemical dehydrating agent. Examples of such hydrocarbons include heptane, hexane, toluene, isopentane and the like.

Zirconocene and methylalumoxane, which are normally soluble in hydrocarbons, are converted to heterogeneous supported catalysts by deposition of dehydrated silica. The order of addition of zirconocene and methylalumoxane may vary. For example, zirconocene (as such or in the form of a solution in a suitable hydrocarbon solvent) may be added to the silica, followed by addition of methylalumoxane. However, the methylalumoxane and the zirconocene may also be added simultaneously to the silica, or the methylalumoxane may be added to the silica first before the zirconocene is added. According to a preferred embodiment of the invention, this operation is carried out by adding methylalumoxane dissolved in the same or a different suitable inert hydrocarbon solvent to the silica suspended in a suitable inert hydrocarbon solvent and then adding zirconocene to the resulting suspension.

The support described above is carried out in an inert solvent. The same or different inert solvents may also be used to dissolve zirconocene and methylalumoxane. Preferred solvents are mineral oils and various hydrocarbons which are flammable at reaction temperatures and in which the individual components are soluble. Illustrative examples of suitable solvents include alkanes such as pentane, iso-pentane, hexane, heptane, octane and nonane; cycloalkanes such as cyclopentane and cyclohexane; and aromatic hydrocarbons such as benzene, toluene, ethylbenzene and diethylbenzene. Preferably the silica is suspended in toluene and zirconocene and methylalumoxane are added to the resulting suspension in the form of toluene solutions. The amount of solvent used is not critical. However, an amount of solvent should be used to ensure appropriate heat dissipation from the catalyst components during the reaction and to allow good mixing.

The supported catalyst according to the invention is prepared simply by adding the reactants in a suitable solvent and preferably in toluene to the silica suspended in toluene. The components may be added rapidly or slowly to the reaction vessel. The temperature maintained during contact of the reactants may be within a wide range, for example from 0 to 100 ° C.

Higher or lower temperatures can also be used. Methylalumoxane and zirconocene are added to the silica at room temperature. The reaction between methylalumoxane and silica is rapid but it is advisable to maintain alumoxari. in contact with the silica for a period of about one to about 18 hours or more.

Preferably, the reaction is carried out for about one hour. The reaction of methylalumoxane, zirconocene and silica is manifested by exothermic heat development and color change.

In all cases, the individual components as well as the catalyst component obtained are protected from oxygen and moisture. The reaction must therefore be carried out in an oxygen and moisture-free atmosphere, and the reaction product must be isolated under the same conditions. Preferably, therefore, the reactions are carried out in the presence of a dry inert gas such as nitrogen. The isolated solid catalyst is maintained under a nitrogen atmosphere.

After the reaction of zirconocene and methylalumoxane with silica is complete, the solid is isolated in a manner known per se. The solid may be recovered from the liquid medium by, for example, evaporating the liquid under vacuum or decanting. Finally, the solid is dried in a stream of pure dry nitrogen or under vacuum.

The amounts of methylalumoxane and zirconodene useful in the preparation of the solid supported catalyst may vary within wide limits. The concentration of methylalumoxane added to the substantially dry silica may range from about 0.1 to about 10 mmol / g of carrier, but may be 1 or more. Preferably, the concentration of methylalumoxane is in the range of from 0.5 to 10 mmol / g of carrier, preferably from 1 to 5 mmol / g of carrier. Typically, the zirconocene is added in an amount to achieve a molar ratio of aluminum to zirconium of from about 1: 1 to about 100: 1. Preferably, the ratio is in the range of about 5: 1 to about 50: 1, and most preferably in the range of about 10: 1. This ratio is substantially lower than that required in a homogeneous system.

According to the invention, at least one zirconocene is used in the preparation of the supported catalyst, Zirconocene is a zirconium derivative of cyclopentadiene. The zirconocenes preferably used according to the invention contain at least one cyclopentadiene ring. The cyclopentadienyl ring may be unsubstituted or may contain substituents such as a hydrocarbon substituent. Zirconocene may contain one, two or three cyclopentadlenyl rings, but two rings are preferred.

Preferred zirconiums are within the scope of Formula I

(I) where

Cp represents a cyclopentadienyl ring, represents a hydrocarbon radical or a hydrocarbyloxy radical, in which the term hydrocarbyl radical denotes a hydrocarbon radical having 1 to 20 carbon atoms,

CS 273 318 B2

X is halogen,

m represents number with value 1 to 3, n represents number with value 0 to 3. q represents number with value 0 to 3, wherein

(m + n + q) has a value corresponding to the oxidation state of zirconium, of formula II or III ^ ^C 5 ^R k \ ^R ^ ^C ^ ^R k 5 ^{ZrC |} 3-g ^R s (C5 ^R 'k) ₂ ZrQ' (III) wherein (C ^{1 R} ₃ P) is cyclopentadienyl or substituted cyclopentadienyl, each of the substituents

R ', which may be the same or different, represent a hydrogen or a hydrocarbon radical selected from the group consisting of alkyl, alkenyl, aryl, alkylaryl or arylalkyl of 1 to 20 carbon atoms, or two carbon atoms are joined together to form a 4-ring up to 6 carbon atoms,

R is (C 1 -C 4) alkylene, dialkylgermanium or silicon, or an alkylphosphino- or amino group bridging two C 1 R 4 rings,

Q is a hydrocarbon radical selected from the group consisting of aryl, alkyl, alkenyl, alkylaryl or arylalkyl of 1 to 20 carbon atoms, hydrocarbyloxy in which hydrocarbyl is a hydrocarbon radical of 1 to 20 carbon atoms, or halogen, each the substituents Q are the same or different,

Q představuje represents an alkylidene radical containing 1 to 20 carbon atoms, s is an integer of 0 or 1, g is an integer of 0, 1 or 2, with s equal to 0 when g is equal to and

k represents 4 when s is 1 and 5 when s is 0 and

M is as defined above.

Examples of hydrocarbon radicals include methyl, ethyl, propyl, butyl, amyl, isoamyl, hexyl, isobutyl, heptyl, octyl, nonyl, decyl, cetyl-, 2-ethylhexyl -, phenyl, and the like.

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

Examples of hydrocarbyloxy groups include methoxy, ethoxy, propoxy, butoxy, amyloxy and the like.

Examples of alkylidene radicals include methylidene, ethylidene and propylidene.

Illustrative but not limiting examples of zirconocenes of formula I include dialkylzirconenes such as bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium diphenyl, bis (cyclopentadienyl) zirconium dinine, bis (cyclopentadienyl) zirconium zirconium zirconium dibenzyl, zirconium ethyl chloride, bisCyclopentadienesDzirconiumphenyl chloride,

E 273 318 82 bis (cyclopentadienyl) zirkoniummethylbromid, bis (cyklopentadienyDzirkoniummethyljodid, bis (cyclopentadienyl) zirkoniumethylbromíd, bis (cyclopentadienyl) zirkoniumethyljodid bis (cyclopentadienyl) zirkoniumfenylbromid, bis (cyclopentadienyl) zlrkoniumfenyljodid; trialkyl metallocenes such as cyklopentadienýlzirkoniumtrifenyl and cyklopentadienylzirkoniumtrlneopentyl and cyklopentadienylzirkoniumtrimethyl.

Illustrative, but non-limiting, examples of zirconocenes of formula II and III useful in the present invention include pentamethylcyclopentadienylzirconium trichloride, pentaethylcyclopentadienylzirconium trichloride, bisCpentamethylcyclopentadienylDisirconium diphenyl, phenyl substituted with cyclopentadiene, phenyl cyclopentadiene, phenyl cyclopentadiene, methylcyclopentadienyl) zirconium dimethyl, bis (n-butylcyclopentadienyl) zirconium dimethyl, bis (cyclohexylmethylcyclopentadienyl) zirconium dimethyl, bis (n-octylcyclopentadienyl) zirconium dimethyl and haloalkyl and dihalogenalkyl alkyl complexes of the above-mentioned compounds; (pentamethylcyclopentadienes) Zirconium dimethyl, bis (1,2-dimethylcyclopentadienyl) zirconium dimethyl and dihalide complexes of the above compounds; silicon, phosphorus and carbon-bridged cyclopentadiene new complexes such as dimethylsilyldicyclopentadienylzirconium dimethyl or -dihalide and methylenedicyclopentadienylzirconium dimethyl or -dihalide and methylondicyclopentadienylzirconium dimethyl or -dihalide, carbenes of the formula

Cp ₂ Zr = CHP (C ₆ H ₅ ) ₂ CH ₃ , and derivatives of these compounds, such as compounds of formula

Cp ₂ ZrCH ₂ CH (CH ₃ ) ₃ CH ₂ .

Certain specific silica particle size, specific surface area, pore volume, and number of surface hydroxy groups, which are the characteristics of the support, are not critical to its utility in the practice of the invention. However, since these properties determine the amount of silica to be used in the preparation of the catalyst systems and further affect the properties of the polymers produced by these catalyst systems, it is often necessary to take these properties into consideration when selecting silica for a particular application. For example, when the catalytic system is to be used in the impact phase polymerization, a type of process known to vary the particle size of the polymer by varying the carrier particle size, the silica used to prepare the catalyst system should have a particle size that is suitable for producing a polymer having the desired particle size. Usually, optimum results are obtained using silica having a mean particle size in the range of about 30 to 600 nm, preferably about 30 to 100 µm; surface area ranging from about 50 to 1000 m g, preferably from about 100 to 400 m ² .g ^{- '1'} and a pore volume of from about 0.5 to 3.5 centimeters .g ^ ^{- '1'} preferably from about 0.5 to about 2 cm .g ^ ^{- '1'.}

The polymerization can be carried out in solution, suspension or gas phase, usually at a temperature in the range of about 0 to 160 ° C or even higher and at atmospheric or reduced or elevated pressure. Conventional polymerization excipients such as hydrogen can be used. In the polymerization of ethylene alone or in copolymerization thereof with one or more higher alpha-olefins, it is generally preferred to use catalytic systems in an amount to achieve a concentration of about 0.000001 to 0.005%, preferably about 0.00001 to 0.0003% by weight. % of the transition metal, based on the weight of the monomer or monomers.

The slurry polymerization can be carried out at a pressure lower than or higher than atmospheric pressure and at a temperature in the range of 40 to 110 ° C. In suspension polymerization, a suspension of solid polymer particles is formed in a liquid polymerization medium to which ethylene, an alpha-olefin comonomer, hydrogen and a catalyst are added. Like a liquid that serves

As a polymerization medium, an alkane or cycloalkane such as butane, pentane, hexane or cyclohexane or an aromatic hydrocarbon such as toluene, ethylbenzene or xylene may be used. The medium used should be liquid and relatively inert under polymerization conditions. Hexane or toluene is preferably used.

The gas phase polymerization is carried out at a pressure above atmospheric pressure and at a temperature in the range of about 50 to about 120 ° C. The gas phase polymerization can be carried out in a stirred or fluidized bed of catalyst and product particles placed in a pressure vessel which is adapted to allow separation of product particles from unreacted gases. Thermostatic ethylene, comonomer, hydrogen and an inert diluent such as nitrogen may be introduced or re-circulated into the bed to maintain the particles at a temperature of from 50 to 120 ° C. Trimethyl aluminum may be added as needed to trap any impurities such as water, oxygen and other substances. The polymer product may be withdrawn continuously or semi-continuously at a rate such that a constant composition is maintained in the reactor. After polymerization and deactivation. The catalyst can be isolated by any suitable method. In industrial practice, the polymer product is obtained directly from the gas-phase polymerization reactor, freed of residual monomer by purging with nitrogen and used without further deactivation or catalyst removal. The obtained polymer can be extruded into water and cut into pellets or other suitable small molded particles. Pigments, antioxidants or other additives known in the art may be added to the polymer.

The molecular weight of the polymer product obtained according to the invention may vary within a wide range of from 500 to 2000,000 or even higher, preferably from 1000 to about 500,000.

If a polymer product with a narrow molecular weight distribution is to be produced, preferably only one zirconocene is deposited on the inert porous support, and the supported zirconium on the support together with the alumoxane is used as the polymerization catalyst.

For many applications, such as extrusion or molding or other forming, it is highly desirable to use polyethylenes with a broad molecular weight distribution, which may be of the unimodal and / or multimodal type. These polyethylenes have excellent processability, i.e. they can be processed with faster throughput and lower energy consumption, while exhibiting fewer disturbances in the melt flow. Such polyethylenes could be obtained by using a catalyst component comprising at least two different zirconocenes, each having a different propagation and termination rate constant in ethylene polymerization. These rate constants can be readily determined by one skilled in the art.

The molar ratio of zirconocenes in these catalysts may vary over a wide range, and the only limitation of this molar ratio is the width of the molecular weight distribution or the degree of bimodality required for the polymer product. The desired molar ratio is in the range of about 1: 100 to about 100: 1, and preferably about 1: 10 to about 10: 1.

The catalyst produced by the process of the present invention can also be used in the manufacture of (co) polyolefin polymer blends produced directly in the reactor. These reactor polymer blends are obtained directly in a single polymerization process. Indeed, such mixtures are prepared in a single reactor at the same time by the polymerization of ethylene and the copolymerization of ethylene with an alpha-olefin, thereby eliminating the costly mixing opacity. The process for producing reactor blends can be used in conjunction with other known mixing technologies.

For example, the mixtures produced in the first reactor may be subjected to further mixing in the second stage using a series of reactors.

To obtain reactor mixtures, the supported metallocene-containing catalyst component must contain at least two different metallocenes, each having a different reactivity ratio to the individual comonomers.

The values of the ratio of reactivities to comonomers for metallocenes are determined by well known methods, such as those described in the Linear Method for Determining Monomer Reactivity of Ratios in Copolymerization, M. Fineman and S. 0. Ross. 3. Polymer Science

CS 273-318 B2, 259 (1950) or Copolymerization, F.R. Mayo and C. Walling, Chem. Roar. 46, 191 (1950). The most commonly used copolymerization model for determining reactivity ratios is based on the following equations (1) - (4)

Μ, + M.

411 (1) ^M 1 ^{+ M} 2

412 (1)

*, * + M

421 (2)

M +

422 (4) where

NL represents a monomer molecule randomly referred to as index £, where £ is 1 or 2,

M * represents a chain of growing polymer whose last linked monomer unit is derived from monomer 6a

k.j represent the rate constants of said reactions.

In the present case, k is the rate constant of the reaction at which the ethylene unit approaches the growing polymer chain, in which the last monomer unit accessed is also the ethylene unit. The ratios of reactivities (copolymerization parameters) are expressed by the relations ^r 1 ^{= k} 11 ^{// k} 12 ^{and r} 2 ^{= k} 22 ^ ^k 21 where ' ^k 11' ^k 12 ' ^k 22 ^and 21 3 ^SQU rate constants of reactions in which the ethylene unit binds (1) or a comonomer (2) to the reactive end of a catalyzed chain on which the last polymerized monomer unit is ethylene (k · ^) or a comonomer (2)

Since it is possible according to the invention to produce high viscosity polymer products at a relatively high temperature, it is not a temperature limiting parameter, as was the case with the prior art metallocene / alumoxane catalysts. The catalyst systems of the present invention are therefore suitable for polymerization of olefins in a solution, suspension or gas phase process that is carried out over a wide range of operating temperatures and pressures. For example, the operating temperature may range from about -60 to about 280 ° C, particularly from about 0 to about 160 ° C. The process of the invention may be carried out under well-known pressure conditions, for example in the range of from about 0.1 to about 50 MPa, but may also be carried out at higher pressures.

The polymers produced by the process of the invention can serve to produce a wide variety of articles, similar to the known ethylene homopolymers and copolymers of ethylene and higher alpha-olefins.

In suspension polymerization, the alkyl aluminum which serves to trap the impurities is preferably dissolved in a suitable solvent, usually an inert hydrocarbon solvent, such as toluene, xylene and the like, at a molar concentration of about ⁵ x 10 ³ M. However, it can also be used in larger or smaller quantities.

The invention is illustrated by the following examples. Examples have illustrations

The present invention is not to be construed as limiting the scope and scope of the invention.

Examples

In the following examples, the alumoxane used is prepared by adding 76.5 g of ferrous sulfate heptahydrate over two hours in four equally divided portions with rapid stirring to a 2 liter round bottom flask containing 1 liter of trimethyl aluminum (TMA) in toluene at a concentration of 13.1% by weight. The flask was maintained at 50 ° C and under a nitrogen atmosphere. The methane formed is continuously discharged. After the addition of all ferrous sulfate heptahydrate, the contents of the flask were continuously stirred for 6 hours while maintaining the temperature at 50 ° C. The reaction mixture was cooled to room temperature and allowed to settle. The clear alumoxane-containing solution is separated from the insoluble solids by decantation.

Molecular weight was determined by gel permeation chromatography on a Water apparatus with Associates Model No. 1. 150 C GPC. Measurements are made by dissolving the polymer samples in hot trichlorobenzene and filtering. GPC assays were performed at 145 ° C in trichlorobenzene at a flow rate of 1.0 ml / min using a styrogelave column (Perkin Elmer Inc). The concentration of the injected sample in trichlorobenzene is 3.1% and its volume is 300 [mu] l. Each measurement is performed twice. Parameter integration is performed using the Hewlett-Packard Data Module.

Preparation of the catalyst

Catalyst A g of high surface area silica (Davison 952), dehydrated by heating at 800 ° C for five hours under a stream of dry nitrogen, was suspended under nitrogen at 25 ° C in 50 ml of toluene in a 250 ml round bottom flask equipped with a magnetic stirrer. 25 ml of methylalumoxane in toluene (1.03 mol / l, calculated as aluminum) was added dropwise to the silica slurry over 5 minutes with constant stirring. Stirring was continued for 30 minutes while maintaining the temperature at 25 ° C and then separating the solid by decanting toluene. 25.0 ml of a toluene solution containing 0.200 g of dicyclopentadienylzirconium dichloride was added dropwise to the alumoxane-treated silica over five minutes. The suspension is stirred for another half hour while maintaining the temperature at 25 ° C, then the toluene is decanted, the solids are separated and dried under vacuum for 4 hours. The isolated solid is neither soluble nor extractable in hexane. Analysis of the catalyst showed that the product contained 4.5 wt% aluminum and 0.63 wt% zirconium.

Catalyst B

This catalyst shows that the use of the catalyst of the present invention in the production of a copolymer of ethylene and 1-butene results in more efficient incorporation of 1-butene. This effect is documented by the density of the polymer product.

Catalyst B is prepared in the same manner as Catalyst A, except that the treatment of the support with methylalumoxane is omitted. The solid obtained contained 0.63% zirconium and 0% aluminum by analysis.

Catalyst C

The procedure for preparing Catalyst A was repeated except that 0.300 g of bis (cyclopentadienyl) zirconium dimethyl was used in place of bis (cyclopentadienyl) zirconium dichloride.

According to the analysis, the solid obtained contained 4.2% by weight aluminum and 1.1% by weight zirconium.

Catalyst D

The procedure for preparing Catalyst A was repeated except that 0.270 g was used

CS 273 318 B2 bis (n-butylcyclopentadienyl) zirconium chloride instead of bis (cyclopentadienyl) zirconium dichloride and all operations are carried out at 80 ° C. The solid obtained contained 0.61% zirconium and 4.3% aluminum by analysis.

Catalyst E

The procedure is the same as for the preparation of Catalyst D except that 0.250 g of bis (n-butylcyclopentadienyl) zirconium dimethyl is used instead of the metallocene dichloride according to Example 0. Analysis of the solid obtained shows that the product contains 0.63% zirconium by weight and 4% by weight. 2% by weight of aluminum.

Catalyst F

The procedure is the same as for the preparation of Catalyst D, except that 0.500 g of bis (pentamethylcyclopentadienyl) zirconium dichloride is used in place of the metallocene of Example 0. Analysis of the solid obtained shows that the product contains 0.65% by weight of zirconium and 4.7% by weight. weight aluminum.

Example 1

Polymerization using Catalyst A

The polymerization is carried out in the gas phase in a 1 liter reaction autoclave equipped with a paddle stirrer, an outer water jacket for temperature control and a septum feed to which dry nitrogen, ethylene, hydrogen and 1-butene can be controlled. The reactor containing 40.0 g of ground 10 mesh (2.0 mm) ground polystyrene, which was added to facilitate gas phase stirring, was dried and degassed thoroughly at 85 ° C. To remove traces of oxygen and water, inject 2.00 mL of methylalumoxane solution (0.64 molar, based on aluminum content) into the vessel via a gas tight syringe. The reactor contents were stirred at a speed of 120 min ^-1 for 1 minute at 85 ° C and a pressure of 6.87 kPa of nitrogen, injected into the reactor with 500.0 Aig catalyst A, and then to it shall ethylene until an overpressure of 1.374 MPa. The polymerization is carried out for 10 minutes, during which time the temperature in the reactor is maintained at 85 ° C and the pressure at 1,374 MPa with a constant feed of ethylene. The reaction is quenched by rapid cooling and venting. 12.3 g of polyethylene are obtained.

The polyethylene is isolated by stirring the product in 1 liter of dichloromethane at 40 ° C, filtering and washing the filter cake with dichloromethane. This separates the insoluble polyethylene product from the soluble polystyrene mixing aid. Polyethylene has a molecular weight of 146,000.

Example 2

Polymerization using Catalyst A

The polymerization is carried out in the same manner as in Example 1 in the presence of Catalyst A, except that 20.61 kPa of hydrogen are pressurized into the reactor before the ethylene feed. 13.2 g of polyethylene having a molecular weight of 29000 are obtained.

Example 3

Polymerization using Catalyst A

The polymerization is carried out in the same manner as in Example 1 in the presence of the catalyst A pause, except that after the catalyst has been injected the catalyst is pressed. 13.0 ml (0.137 mol) of 1-butene together with ethylene. 13.8 g of polyethylene having a molecular weight of 39000 and a density of 918 kg / m ^< ^{5 &gt}; are obtained.

CS 273 318 B2

Comparative Example 3A

Polymerization using Catalyst B

The polymerization was carried out in the same manner as in Example 3, except that catalyst B was used instead of catalyst A. 17.3 g of polyethylene having a molecular weight of 67000 and a density of 935 kg / m ^{3 were obtained} . A higher density compared to the density of the polymer obtained in Example 3 shows that comonomer incorporation was less effective.

Example 4

Polymerization using Catalyst C

The polymerization was carried out in the same manner as in Example 1 except that catalyst C was used instead of catalyst A. 9.8 g of polyethylene having a molecular weight of 189000 and a density of 9'60 kg / m ^{3 were obtained} .

Example 5

Polymerization using Catalyst C

The polymerization was carried out as described in Example 4, except that 13.0 ml (0.123 mol) of 1-butene and 4.122 kPa (1.66 mmol) of hydrogen were introduced into the reactor together with ethylene after injection of the catalyst. 6.5 g of polyethylene having a molecular weight of 41000 and a density of 926 kg / m @ ^{3 are obtained} .

Example 6

Polymerization using Catalyst C

The polymerization is carried out as described in Example 4, except that methylalumoxane is not used to remove impurities and no other alkyl aluminum dirt trap is used. 10.2 g of polyethylene having a molecular weight of 120000 and a density of 960 kg / m @ ^{3 are obtained} .

Example 7

Polymerization using Catalyst D

The polymerization was carried out as described in Example 1 except that 0.6 ml of a 25% by weight solution of triethylaluminum in hexane and catalyst D were used instead of catalyst A. 50.5 g of polyethylene were obtained. with a molecular weight of 196000 and a density of 958 kg / m ³ .

Example B

Polymerization using Catalyst D

The polymerization was carried out as described in Example 1, except that the methylalumoxane was discharged as an impurity acceptor, catalyst D was used instead of catalyst A, and the polymerization was stopped at the end of 5 minutes. 28.8 g of polyethylene having a molecular weight of 196000 and a density of 958 kg / m @ ^{3 are obtained} .

CS 273 318 B2

Example 9

Polymerization using Catalyst E

The polymerization was carried out as described in Example 8, using catalyst E and without using an aluminum impurity acceptor. 24.0 g of polyethylene having a weight average molecular weight of 190000, a number average molecular weight of 76000 and a density of 958 kg / m ^{3 are obtained} .

Example 10

Polymerization using Catalyst F

The polymerization was carried out as described in Example 7 except that 0.500 g of catalyst F was used instead of catalyst D. 8.1 g of polyethylene having a molecular weight of 137000 and a density of 960 kg / m @ ^{3 were obtained} .

SUBJECT OF THE INVENTION

Claims (3)

A process for the preparation of a supported olefin polymer of silica-containing olefins as a carrier and a reaction product of at least one zirconocene and methylalumoxane, wherein methylalumoxane and zirconocene are added to the silica suspension in a hydrocarbon, characterized in that the molar ratio of aluminum to zirconium it is in the range of 100: 1 to 1: 1 and the alumoxane is added to the carrier in an amount of from 0.1 to 10 mmol per gram of carrier. 2. The process of claim 1 wherein the molar ratio of aluminum to zirconium is in the range of 50: 1 to 5: 1. 3. The method of claim 1 wherein the zirconocene is selected from the group consisting of bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dimethyl, bis (pentamethylcyclopentadienyl) zirconium dichloride, bis (n-butylcyclopentadienyl) zirconium dichloride dichloride. ) zirconium dimethyl.