GB2133020A - Polymerising olefins with an improved Ziegler catalyst - Google Patents

Abstract

At least one olefin is polymerized using a catalyst which consists essentially of: [I] a solid catalyst component obtained by contacting and reacting the following components (1)-(4) with one another: (1) a silicon oxide and/or an aluminum oxide, (2) a reaction product resulting from the reaction of a magnesium halide and a compound represented by the general formula Me(OR)nXz-n wherein Me is an element selected from Groups I through VIII of the Periodic Table, provided silicon, titanium and vanadium are excluded, R is a hydrocarbon radical having 1 to 24 carbon atoms, X is a halogen atom, z is the valence of Me and n is 0<n</=z, (3) a compound represented by the general formula <IMAGE> wherein R<1>, R<2> and R<3> are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen or a halogen atom, R<4> is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1</=n</=30, and (4) a titanium compound and/or a vanadium compound; [II] a compound represented by the general formula <IMAGE> wherein R<1>, R<2> and R<3> are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen or a halogen atom, R<4> is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1</=n</=30; and [III] an organometallic compound.

Description

SPECIFICATION Process for preparing polyolefins BACKGROUND OF THE INVENTION The present invention relates to a process for polymerizing or copolymerizing a-olefins in high activity using a novel catalyst.

Catalysts comprising titanium halides and organoaluminum compounds have heretofore been known as catalysts for obtaining high stereospecific polymers of oe-olefins. Indeed, a polymerization using such catalyst affords a high stereospecific polymer, but it is necessary to remove the catalyst remaining in the resultant polymer because of a low catalytic activity.

Recently, many proposals have been made for improving the catalytic activity. These proposals show that a high activity catalyst is obtained by using a catalyst component which comprises an inorganic solid carrier such as, for example, MgCI2 and titanium tetrachloride supported thereon.

However, in the production of polyolefins it is desirable that the catalytic activity be as high as possible. From this standpoint, catalysts of a higher activity have been desired. In the case of a stereospecific polymer, moreover, it is important that the proportion of an atactic portion be as small as possible.

Further, in those conventional processes, the average particle diameter of the resultant polymer is relatively small, the particle size distribution is generally wide and the proportion of a finely divided powder is large. Therefore, from the aspects of productivity and slurry handling, improvements have been strongly desired. Moreover, molding of such polymer causes problems such as the formation of dust and the lowering of the molding efficiency. For this reason, the increase of bulk density and the reduction of the proportion of a finely divided powder have strongly been desired. Additionally, it has recently been desired to omit the pelletizing step and supply the powdered polymer directly to a processing machine. To meet this demand, however, still further improvements have been considered necessary.

Having made extensive studies on the above-mentioned points, the present inventors invented a novel catalyst. More particularly, it is the first object of the present invention to provide a process for preparing high stereospecific polyolefins in high activity by the use of a novel catalyst. The use of the catalyst of the invention permits a short-time polymerization at a low partial pressure of monomer, and yet the amount of the catalyst remaining in the resultant polymer is extremely small. Consequently, various effects are obtainable; for example, the catalyst removing step can be omitted from the polyolefin manufacturing process, and the proportion of an atactic por tion in the resultant polymer is extremely small.

According to the process of the present invention, polyolefins having a high stereospe cificity, a large average particle size, a narrow particle size distribution and a small propor tion of a finely divided powder are obtained.

Besides, those polyolefins have a high bulk density. These characteristics are very advan tageous to the polymerizing operation. Fur ther, not only as pellets, but also directly as powder, those polyolefins can be subjected to a molding operation without causing a serious trouble. Thus, the process of the present invention permits an extremely advantageous production of polyolefins.

On the other hand, attempts have recently been made to prepare soft or semi-hard olefin copolymers by using Ziegler type catalysts. On this regard, however, the conventional pro cesses have drawbacks. For example, the op eration is complicated and the quality of the resultant polymer is poor.

It is the second object of the present inven tion to provide a process for preparing novel, soft or semi-hard olefin copolymers having a density in the range of 0.860 to 0.910g/cm3 by using a novel Ziegler type catalyst. Accord ing to this process of the invention, such olefin copolymers having an ultra-low density can be prepared stably so that the copolymers are less sticky and have good particle proper ties and a high bulk density, consequently with little adhesion to the reactor or agglomer ation of the polymer particles even in a contin uous run over a long period of time.

SUMMARY OF THE INVENTION The present invention resides in a process for preparing a polyolefin by polymerizing at least one olefin in the presence of a catalyst, which catalyst comprises a combination of: [I] a solid catalyst component obtained by contacting and reacting the following compo nents (1)-(4) with one another:: (1 ) a silicon oxide and/or an aluminum oxide; (2) a reaction product resulting from the reaction of a magnesium halide and a com pound represented by the formula Me(OR),X,~, wherein Me is an element se lected from Groups I through VIII of the Periodic Table, provided silicon, titanium and vanadium are excluded, R is a hydrocarbon radical having 1 to 24 carbon atoms, X is a halogen atom, z is the valence of Me and n is O < nCz, (3) a compound represented by the general formula

wherein R', R2 and R3 are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen or a halogen atom, R4 is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1 n30, and (4) a titanium compound and/or a vanadium compound;; (Il] a compound represented by the general formula

wherein R1, R2 and R3 are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen or a halogen atom, R4 is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1'n'30; and lll] an organometallic compound.

According to the process of the present invention, a soft copolymer having a density in the range of 0.860 to 0.910 g/cm3 can be prepared by carrying out a polymerization of propylene in the first stage and then conducting in the second stage a copolymerization of ethylene and proplylene and/or butene-1 in a substantially solvent-free condition.

PREFERRED EMBODIMENTS OF THE INVEN TION The silicon oxide used in the present invention is silica or a double oxide of silicon and at least one other metal selected from Groups I through VIII of the Periodic Table.

The aluminum oxide used in the present invention is alumina or a double oxide of aluminum and at least one other metal selected from Groups I through VIII of the Periodic Table.

As typical examples of such double oxide of silicon or aluminum and at least one other metal selected from Groups I through VIII of the Periodic Table, mention may be made of various natural and synthetic double oxides such as AI2O3Mg0, Al203 CaO, Al203 SiO2, Al203 MgO CaO, Al2O3 Mg0'SiO2, Al203 CuO, Al20Fe2O3, Al2O3NiO and SiO2 MgO. These formulae are not molecular formulae, but represent only compositions. The structure and component ratio of double oxides which may be used in the invention are not specially limited. The silicon oxide and/or aluminum oxide used in the present invention may contain small amounts of adsorbed water and impurities.

The magnesium halide used in the present invention is substantially anhydrous, examples of which include magnesium fluoride, magnesium chloride, magnesium bromide and magnesium iodide, with magnesium chloride being particularly preferred. These magnesium halides may be treated in advance with electron donors such as, for example, alcohols, esters, ketones, carboxylic acids, ethers, amines and phosphines.

As examples of the compound of the general formula Me(OR)nXz~n used in the present invention-in which formula Me is an element selected from Groups I through VIII of the Periodic Table, provided silicon, titanium and vanadium are excluded, R is a hydrocarbon radical having 1 to 24 carbon atoms, X is a halogen atom, z is the valence of Me and n is O < nz-, mention may be made of the following compounds: NaOR, Mg(OR)2, Mg(OR)X, Ca(OR)2, Zn(OR)2, Zn(OR)X, Cd(OR)2, Al(OR)3, Al(OR)2X, B(OR)3, B(OR)2X, Ga(OR)3, Ge(OR)4, Sn(OR)4, P(OR)3, Cr(OR)2, Mn(OR)2, Fe(OR)2, Fe(OR)3, Co(OR)2 and Ni(OR)2.As more concrete examples, the following compounds are preferred: NaOC2H5, NaOC4Hg, Mg(0CH3)2, Mg(0C2H5)2, Mg(OC3H7)2t Ca(OC2H5)2, Zn(OC2H5)2, Zn(OC2H5)CI, Al(OCH3)3, Al(OC2H5)3, Al(OC2H5)2CI, Al(OC3H7)3, Al(0C4Hs)3, Al(OC6H5)3, B(0C2H5)3, B(OC2H5)2Cl P(OC2H5)3, P(OC6H5)3 and Fe(OC4Hg)3.

Compounds represented by the general formula Mg(OR)nX2~n, Al(OR)nX3~n and 8(OR)nX3~n are particularly preferred in the present invention. As the substituent R, alkyl groups having 1 to 4 carbon atoms and phenyl group are especially preferred.

The method of reacting the magnesium halide with the compound of the general formula Me(ORnXI~n is not specially limited.

Both may be mixed and reacted under heating at a temperature of 20 to 400"C, preferably 50 to 300"C, for 5 minutes to 10 hours in an organic solvent such as an alcohol, an ether, a ketone, or an ester. Alternatively, both may be reacted by a co-pulverization treatment.

The reaction method utilizing a co-pulverization treatment is particularly preferred in the present invention. The apparatus to be used for the copulverization is not specially limited.

Usually, a ball mill, a vibration mill, a rod mill or an impact mill may be used. Conditions such as the pulverizing temperature and time can be decided easily by those skilled in the art according to how to pulverize. Generally, the pulverizing temperature ranges from 0" to 200"C, preferably 20 to 100"C, and the pulverizing time ranges from 0.5 to 50 hours, preferably 1 to 30 hours. Of course, the copulverizing operation should be performed in an inert gas atmosphere, and moisture should be avoided as far as possible.

The reaction ratio of the magnesium halide and the compound of the general formula Me(OR)nXz~n is in the range of 1:0.01 to 1:10, preferably 1:0.1 to 1:5, in terms of Mg: Me (mole ratio).

To exemplify the compound of the general formula

used in the present inventionin which formula R', R2 and R3 are each a hydrocarbon radical having 1 to 24, preferably 1 to 18, carbon atoms, an alkoxy group, hydrogen or a halogen atom, R4 is a hydrocarbon radical having 1 to 24, preferably 1 to 18, carbon atoms and n is 1=n='30-, mention may be made of the following:: monomethyltrimethox- ysilane, monomethyltriethoxysilane, monome thyltri-n-butoxysilane, monomethyltri-secbutoxysilane, monomethyltriisopropoxysilane, monomethyltripentoxysilane, monomethyltrioctoxysilane, monomethyltristearoxysilane, monomethyltriphenoxysilane, dimethyidime- thoxysilane, dimethyidiethoxysi lane, di methyl- diisopropoxysilane, dimethyidiphenoxysilane, trimethylmonomethyoxysilane, trimethylmonoethoxysilane, trimethylmonoisopropoxysilane, trimethylmonophenoxysilane, monomethyidi- methoxymonochlorosilane, monomethyidi- ethoxymonochlorosilane, monomethylmonoethoxydichlorosilane, monomethyidiethoxymo- nochlorosilane, monomethyidiethoxymonobro- mosilane, monomethyidiphenoxymonochloro- silane, dimethylmonoethoxymonochlorosilane, monoethyltrimethoxysilane, monoethyltriethoxysilane, monoethyltriisopropoxysilane, monoethyltriphenoxysilane, diethyidimethoxysilane, diethyidiethoxysilane, diethyid iphenoxysilane, triethylmonomethoxysilane, triethylmonoethoxysilane, triethylmonophenoxysilane, monoe thyidimethoxymonochlorosilane, monoethyidi- ethoxymonochlorosilane, monoethyidiphenox- ymonochlorosilane, monoisopropyl-trimethoxy- silane, mono-n-butyltrimethoxysilane, mono-nbutyltriethoxysilane, mono-sec-butyltriethoxysi- lane, monophenyltriethoxysilane, diphenyidi- ethoxysilane, diphenylmonoethoxymonochlo- rosilane, monomethoxytrichlorosilane, monoethoxytrichlorosilane, monoisopropoxytrichloro- silane, mono-butoxytrichlorosilane, monopentoxytrichlorosilane, monooctoxytrichlorosilane, monostearoxytrichlorosilane, monophenoxytrichlorosilane, mono-p-methylphenoxytrichloro- silane, dimethoxydichlorosilane, dioctoxydichlorosilane, trimethoxymonochlorosilane, triethoxymonochlorosilane, triisopropoxymono chlorosilane, tri-n-butoxymonochlorosilane, tri sec-butoxymonochlorosilane, tetraethoxysilane, tetraisopropoxysilane, and chain-like or cyclic polysiloxanes obtained by condensation of the compounds just exemplified which polysiloxanes have recurring units represented by

Mixtures of these compounds are also employ able .

As examples of the titanium compound and/or vanadium compound used in the present invention, there may be mentioned halides, alkoxyhalides, alkoxides and halogen ated oxides of titanium and/or vanadium.

Suitable examples of titanium compounds which may be used in the invention are tetravalent and trivalent titanium compounds.

As tetravalent titanium compounds, those represented by the general formula Ti(OR)nX4~n are preferred in which formula R is an alkyl, aryl or aralkyl group having 1 to 20 carbon atoms, X is a halogen atom and n is 0~n='4. Examples are titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, dimethox yd ichlorotitanium, tri methoxymonoch lorotitan- ium, tetramethoxytitanium, monoethoxytrichlorotitanium, diethoxydichlorotitanium, tri ethoxymonochlorotitan ium, tetraethoxytitanium, monoisopropoxytrichlorotitanium, diisopropoxydichlorotitanium, triisopropoxymonochlorotitanium, tetraisopropoxytitanium, mo nobutoxytrichlorotitanium, d ibutoxyd ichloroti- tanium, monopentoxytrichlorotitanium, monophenoxyrichlorotitanium, diphenoxydichloroti- tanium, triphenoxymonochlorotitanium and tetraphenoxytitanium. To illustrate trivalent ti titanium compounds, mention may be made of titanium trihalides obtained by reducing titanium tetrahalides such as titanium tetrachloride and titanium tetrabromide with hydrogen, aluminum, titanium or an organometallic compound of a metal selected from Groups I through lil of the Periodic Table, as well as trivalent titanium compounds obtained by reducing tetravalent alkoxytitanium halides of the general formula Ti(OR)mX4~m with an organometallic compound of a metal selected from Groups I through lil of the Periodic Table, in which formula R is an alkyl, aryl or aralkyl group having 1 to 20 carbon atoms, X is a halogen atom and m is 0 < m < 4. As examples of vanadium compounds which may be used in the invention, there are mentioned tetravalent vanadium compounds such as va vanadium tetrachloride, vanadium tetrabromide, vanadium tetraiodide and tetraethoxyvanadium; pentavalent vanadium compounds such as vanadium oxytrichloride, ethoxydichlorovanadyl, triethoxyvanadyl and tributoxyvanadyl; and trivalent vanadium compounds such as vanadium trichloride and vanadium triethoxide.

In order to make the present invention more effective, both the titanium compound and the vanadium compound are often used in combination. In this case, it is preferable that the V/Ti molar ratio be in the range of 2/1 to 0.01/1.

As examples of the organometallic compound used in the present invention, there may be mentioned organometallic compounds of metals of Groups I through IV in the Periodic Table which are known as a Ziegler catalyst component. Especially preferred are organo-aluminum compounds and organozinc compounds.Concrete examples are organoal urflinum compounds of the general formulae R3AI, R2AIX, RAIN2, R2AIOR, RAI(OR)X and R3AI2X3 where Rs, which may be alike or different, are each an alkyl or aryl group having 1 to 20 carbon atoms and X is a halogen atom, and organozinc compounds of the general formula R2Zn wherein Rs, which may be alike or different, are each an alkyl group having 1 to 20 carbon atoms, such as triethylaluminum, triisopropylaluminum, triiso butylaluminum, tri-sec-butylaluminum, tri-tertbutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, diethylaluminum chloride, diisopropylaluminum chloride, diethylaluminum monoethoxide, ethylaluminum sesquichloride, diethyl-zinc, and mixtures thereof.

The amount of the organometallic compound used in the invention is not specially limited, but usually ranges from 0.1 to 1 ,000 moles per mole of the transition metal compound or compounds.

Together with the organometallic compound there may be used an ester of an organocarboxylic acid such as, for example, benzoic acid, o- or p-toluic acid or p-anisic acid.

The order and method of contacting and reacting the following components (1) through (4) with one another are not specially limited: (1) a silicon oxide and/or an aluminum oxide, which will hereinafter be referred to simply as component LlJ-(1); (2) a reaction product resulting from the reaction of a magnesium halide and a compound of the general formula Me(OR)nXz~n, which will hereinafter be referred to simply as component all(2); (3) a compound of the general formula

which will hereinafter be referred to simply as component [I]-(3); and (4) a titanium compound and/or a vanadium compound, which will hereinafter be referred to simply as component [l]-(4).

The contacting order is not specially limited.

For example, those components may be contacted first between components rli-(1) and (lJ-(2), then with component (l]-(3) and thereafter with component [1]-(4), or first between components (l]-(1) and [1]-(3) and then with components [lJ-(2) and [1]-(4).

The contacting method is not specially limited, either. Conventional methods may be adopted. For example, those components may be contacted and reacted at a temperature of 20 to 400 C, preferably 50 to 300"C, usually for 5 minutes to 20 hours in the presence or absence of an inert solvent, or they may be reacted by a co-pulverization treatment, or may be reacted by a combination of these methods.

The inert solvent is not specially limited.

Usually, hydrocarbons and/or derivatives thereof which do not inactivate Ziegler type catalysts may be used. Examples are saturated aliphatic hydrocarbons, aromatic hydrocarbons and alicyclic hydrocarbons, such as propane, butane, pentane, hexane, heptane, octane, benzene, toluene, xylene and cyclohexane, as well as alcohols, ethers and esters such as ethanol, diethyl ether, tetrahydrofuran, ethyl acetate and ethyl benzoate.

In the case where the components [l]-(1) through [lJ-(4) are reacted by a co-pulverization treatment, conditions such as the pulverizing temperature and time can be decided easily by those skilled in the art according to the co-pulverization method adopted. Generally, the pulverizing temperature ranges from 0 to 200"C, preferably 20 to 100 C, and the pulverizing time ranges from 0.5 to 50 hours, preferably 1 to 30 hours. Of course, the co-pulverizing operation should be conducted in an inert gas atmosphere, and moisture should be avoided as far as possible.

The most preferred order and method of contacting the components (lJ-(1) through (l]-(4) are as follows.

First, the components [lJ-(1) and (l]-(2) are contacted and reacted together in a solvent capable of dissolving the component 3-(2), i.e., the reaction product of a magnesium halide and a compound of the general formula Me(OR)nXz~n, at a temperature of 0 to 300"C, preferably 10 to 200"C, most prefer ably 20 to 100"C, for 1 minute to 48 hours, preferably 2 minutes to 10 hours. Preferred examples of the above solvent are alcohols, tetrahydrofuran and ethyl acetate. The contacting ratio of both components is 0.01 to 5 g., preferably 0.1 to 2 g., of component (l]-(2) per gram of component [l]-(1). After the reaction, the solvent is removed to obtain a reaction product of both components.

Then, with the reaction product thus ob tained is contacted and reacted the compo nent All(3), i.e., a compound of the general formula

at a temperature of 20 to 400"C, preferably 50 to 300"C, for preferably 5 minutes to 20 hours, directly or in the presence of an inert solvent such as, for example, hexane, heptane, octane, benzene or toluene. The magnesium halide, the compound of the general formula Me(OR)nXz~n and the component El]- (3) may be mixed and reacted at a time.The contacting ratio of the reaction product of components l]-(1) and [1]-(2) and the component (l]-(3) is 0.01 to 5 g., preferably 0.1 to 2 g., of component [1]-(3) per gram of the said reaction product.

Thereafter, with the reaction product of components [1]-(1), [1]-(2) and [l]-(3) is mixed the component [1]-(4), i.e., a titanium compound and/or a vanadium compound, under heating at a temperature of 20 to 300on, preferably 50 to 1 50 C, for 5 minutes to 10 hours, directly or in the presence of an inert solvent such as, for example, hexane, heptane, octane, benzene or toluene, thereby allowing the titanium compound and/or the vanadium compound to be supported on the said reaction product. Preferably, this reaction is carried out in the absence of solvent.The component [1]-(4) is used in such an amount as to provide 0.5 to 50 wt.%, preferably 1 to 20 wt.%, in terms of the amount of the titanium compound and/or vanadium compound contained in the solid catalyst component produced. After the reaction, unreacted titanium compound and/or vanadium compound is removed by washing several times with a solvent which is inert to Ziegler type catalysts. Then, the solvent is evaporated under reduced pressure to obtain a solid powder.

As to the amount of the catalyst component (Il] used in the present invention, i.e., a compound of the general formula

both too large and too small amounts thereof would not be effective. Usually, it is in the range of 0.1 to 100 moles, preferably 0.3 to 20 moles, per mole of the titanium compound and/or vanadium compound contained in the catalyst component [I].

The component [II] may be used as a reaction product resulting from its reaction with the organometallic resulting from its reaction with the organometallic compound. In this case, the reaction ratio is in the range of 1:500to 1:1, preferably 1:100to 1:2, in terms of a molar ratio of the component [ll to the organometallic compound. The product obtained by the reaction of the component [ll and the organometallic compound is used in an amount of preferably 0.1:1 to 100:1, more preferably 0.3:1 to 20:1, in terms of Si Ti and/or V (molar ratio) with respect to the titanium compound and/or vanadium compound in the catalyst component l].

The olefin polymerization using the catalyst of the present invention may be carried out in the form of slurry polymerization, solution polymerization or vapor phase polymerization.

The catalyst of the present invention is particularly suitable for the vapor phase polymerization. The polymerization reaction is carried out in the same way as in the conventional olefin polymerization reaction using a Ziegler type catalyst. That is, the reaction is performed in a substantially oxygen- and waterfree condition and in the presence or absence of an inert hydrocarbon. Olefin polymerization conditions involve temperatures ranging from 20 to 120"C, preferably 50 to 100"C, and pressures ranging from atmospheric pressure to 70 kg/cm2, preferably 2 to 60 kg/cm2.

Adjustment of the molecular weight can be done to some extent by changing polymerization conditions such as the polymerization temperature and the catalyst mole ratio, but the addition of hydrogen into the polymerization system is more effective for this purpose.

Of course, using the catalyst of the present invention there can be performed, without any trouble, two- or more-stage polymerization reactions involving different polymerization conditions such as different kinds and concentrations of monomers, different hydrogen concentrations and different polymerization temperatures. For example, the catalyst of the present invention is extremely suitable for the production of so-called block copolymers usually conducted in the polypropylene manufacturing process, etc.

The process of the present invention is applicable to the polymerization of all olefins that are polymerizable with Ziegler type catalysts. Particularly, a-olefins of C2 to C,2 are preferred. For example, the process of the invention is suitable for the homopolymerization of such a-olefins as ethylene, propylene, butene-1, hexene-1 and 4-methylpentene-1, the copolymerization of ethylene/propylene, ethylene/butene-1, ethylene/hexene-1, and propylene/butene-1, as well as the copolymerization of ethylene and two or more other CL- olefins.

Copolymerization with dienes for the modification of polyolefins is also preferable, for example, with butadiene, 1,4-hexadiene, ethylidene norbornene and dicyclopentadiene.

The process of the present invention is effective particularly for the production of high stereospecific homo- or copolymers of C3 to C8 a-olefins and for the production of soft copolymers of ultra-low densities.

In the production of such soft copolymers, first a polymerization of propylene is performed according to a conventional polymerization method, for example, slurry polymerization, bulk polymerization, or vapor phase polymerization. In this case, propylene may be copolymerized with small amounts of other a- olefins such as, for example, ethylene and butene-1. Conditions for the polymerization are not specially limited. The polymerization may be carried out under conditions which are usually adopted in the polymerization of propylene using a Ziegler type catalyst. In this first stage, 9.001 to 80 wt.%, preferably 0.001 to 70 wt.% and more preferably 0.01 to 60 wt.% of polypropylene based on the amount of the final polymer product is produced.

Then, as the second stage, there is performed a copolymerization of ethylene with propylene and/or butene-1. At this time, the reaction mixture obtained in the first stage which contains the polymer produced and unreacted monomer is fed to the second-stage polymerization system directly or after flash evaporation to remove volatilies such as unreacted monomer and solvent to obtain a solid polymer powder. The former, namely, a direct supply of the reaction mixture, is advantageous in that the volatiles can be effectively utilized for removing the heat of polymerization by being evaporated in the second-stage polymerization.The polymerization temperature is usually in the range of 20 to 1 10'C, preferably 40 to 1 00 C, and the polymerization pressure is in the range of atmospheric pressure to 70 kg/cm2G, preferably 2 to 60 kg /cm2 G. The first-stage polymerization reaction may be followed by multi-stage polymerization reactions involving different polymerization conditions such as different polymerization temperatures and different hydrogen and comonomer concentrations. Preferably, of such multi-stage polymerization reactions, the polymerization reaction in at least one stage is carried out in vapor phase.Further, such multi-stage polymerization reactions may be carried out in the presence of dienes such as, for examples, butadiene, 1 4-hexadiene, 1,5hexadiene, vinyl norbornene and ethylidene norbornene.

The following examples serve to illustrate the present invention in more detail, but should not be construed as limiting the invention thereto.

Example 1 (a) Preparation of Solid Catalyst Component 10 g. of a commercially available anhydrous magnesium chloride and 4.2 g. of aluminum triethoxide were placed in a stainless steel pot having a content volume of 400 ml.

and containing 25 stainless steel balls each 1/2 inch in diameter, and ball-milled for 1 6 hours at room temperature in a nitrogen atmosphere to obtain a reaction product. Then, a three-necked flask equipped with a stirrer and a reflux condenser was purged with nitrogen and then charged with 5 9. of the above reaction product and 5 g. of silica (#952, a product of Fuji-Davison) which had been calcined at 600"C, then 100 ml. of tetrahydrofuran was added and reaction was allowed to take place at 60"C for 2 hours. Thereafter, tetrahydrofuran was removed by drying at 120"C under reduced pressure. Then, 50 ml.

of hexane was added, and after stirring, 1 ml.

of tetraethoxysilane was added and reaction was allowed to take place for 2 hours under reflux of hexane to obtain a solid powder (A).

The solid powder (A) thus obtained was added into 30 ml. of titanium tetrachloride and reaction was allowed to take place at 120"C for 2 hours. Thereafter, the reaction mixture was washed with hexane until titanium tetrachloride was no longer detected in hexane, to obtain a solid catalyst component containing 70 mg. of titanium per gram thereof.

(b) Vapor Phase Polymerization As a vapor phase polymerization apparatus there was used a 5 I stainless steel autoclave equipped with an induction stirrer. Into the autoclave held at 60"C were fed 100 mg. of the above solid catalyst component, 2.5 mmol. of triethylaluminum and 0.5 mmol. of phenyltriethoxysilane, and polymerization was allowed to take place for 8 hours while propylene was fed continuously so as to maintain the total pressure at 8.5 kg/cm2G. As a result, there was prepared 450 g. of polypropylene of spherical particles having a bulk density of 0.40 and an average particle diameter of 1 ,000 Ibm. Catalytic activity was 64,000g.polypropylene/g.Ti. The percent residue of the polypropylene after extraction in boiling heptane was 87 wt.%.

Comparative Example 1 (a) Preparation of Solid Catalyst Component A solid catalyst component was prepared in the same way as in Example 1 except that the tetraethoxysilane was not used. Its titanium content per gram thereof was 35 mg.

(b) Vapor Phase Polymerization Using the solid catalyst component just prepared above, polymerization was carried out in the same manner as in Example 1 except that the phenyltriethoxysilane was not used. As a result, there was prepared 1 50 g.

of polypropylene having a bulk density of 0.35 and an average particle diameter of 700 ,um. Catalystic activity was 43,0009. polypropylene/g.Ti. The percent residue of the polypropylene after extraction in boiling heptane was 40 wt.%.

Example 2 (a) Preparation of Solid Catalyst Component 10 g. of a commercially available anhydrous magnesium chloride and 4.2 g. of aluminum triethoxide were placed in the ball-mill pot described in Example 1, and ball-milled for 1 6 hours at room temperature in a nitrogen atmosphere to obtain a reaction product.

Into the three-necked flask described in Example 1 were charged 2.5 g. of the reception product just prepared and 7.5 g. of silica (*952, a product of Fuji-Davison) which had been calcined at 600"C, then 100 ml. of tetrahydrofuran was added and reaction was allowed to take place at 60"C for 2 hours.

Thereafter, tetrahydrofuran was removed by drying at 120"C under reduced pressure.

Then, 50 ml. of hexane was added, and after stirring, 1 ml. of diethyldiethoxysilane was added and reaction was allowed to take place for 2 hours under reflux of hexane to obtain a solid powder (B).

The solid powder (B) thus obtained was added into 30 ml. of titanium tetrachloride and reaction was allowed to take place at 120"C for 2 hours. Thereafter, the reaction mixture was washed with hexane until titanium tetrachloride was no longer detected in hexane, to obtain a solid catalyst component containing 60 mg. of titanium per gram thereof.

(b) Vapor Phase Polymerization Using the apparatus described in Example 1, a vapor phase polymerization was carried out in the following manner. Into the autoclave held at 60"C were placed 100 mg. of the above solid catalyst component, 2.5 mmol. of triethylaluminum and 0.5 mmol. of phenyltriethoxysilane, and polymerization was allowed to take place for 8 hours while propylene was fed continuously so as to maintain the total pressure at 8.5 kg/cm2.G. As a result, there was prepared 430 g. of polypropylene of spherical particles having a bulk density of 0.45 and an average particle diameter of 900 cm. Catalytic activity was 72,000g.polypropylene/g.Ti. The percent residue of the polypropylene after extraction in boiling heptane was 89 wt.%.

Example 3 (a) Preparation of Solid Catalyst Component 10 g. of commercially available anhydrous magnesium chloride and 1.3 g. of magnesium diethoxide were placed in the ball-mill pot described in Example 1 and ball-milled for 1 6 hours at room temperature in a nitrogen atmosphere to obtain a reaction product. Then, 5 g. of the reaction product just prepared and 5 g. of alumina which had been calcined at 600"C were charged into the three-necked flask described in Example 1, then 100 ml. of tetrahydrofuran was added and reaction was allowed to take place at 60"C for 2 hours.

Thereafter, tetrahydrofuran was removed by drying at 120"C under reduced pressure.

Then, 50 ml. of hexane was added, and after stirring, 2 ml. of tetraethoxysilane was added and reaction was allowed to take place for 2 hours under reflux of hexane to obtain a solid powder (C).

The solid powder (C) thus obtained was added into 30 ml. of titanium tetrachloride and reaction was allowed to take place at 1 20 c for 2 hours. Then, the reaction mixture was washed with hexane until titanium tetrachloride was no longer detected in hexane, to obtained a solid catalyst component containing 100 mg. of titanium per gram thereof.

(b) Vapor Phase Polymerization Using the apparatus described in Example 1, a vapor phase polymerization was carried out in the following manner. 100 mg. of the above solid catalyst component, 2.5 mmol. of triethylaluminum and 0.7 mmol. of tetraethoxysilane were charged into the autoclave held at 60"C and polymerization was allowed to take place for 8 hours while propylene was fed continuously so as to maintain the total pressure at 8.5 kg/cm2,G. As a result, there was prepared 500 g. of polypropylene of spherical particles having a bulk density of 0.41 and an average particle diameter of 950 jtm. Catalytic activity was 50,000g.polypropylene/g.Ti. The percent residue of the polypropylene after extraction in boiling heptane was 92 wt.%.

Example 4 (a) Preparation of Solid Catalyst Component 10 g. of a commercially available anhydrous magnesium chloride and 4.2 g. of aluminum triethoxide were placed in the ball-mill pot described in Example 1 and ball-milled for 1 6 hours at room temperature in a nitrogen atmosphere to obtain a reaction product.

Then, 5 g. of the reaction product just prepared and 5 g. of alumina which had been calcined at 600"C were charged into the three-necked flask described in Example 1, then 100 ml. of tetrahydrofuran was added and reaction was allowed to take place at 60"C for 2 hours. Thereafter, tetrahydrofuran was removed by drying at 1 20'C under reduced pressure. Then, 50 ml. of hexane was added, and after stirring, 2 ml. of diethyldiethoxysilane was added and reaction was allowed to take place for 2 hours under reflux of hexane to obtain a solid powder (D).

The solid powder (D) thus obtained was added into 30 ml. of titanium tetrachloride and reaction was allowed to take place at 1 20'C for 2 hours. Thereafter, the reaction mixture was washed with hexane until titanium tetrachloride was no longer detected in hexane, to obtain a solid catalyst component containing 75 mg. of titanium per gram thereof.

(b) Vapor Phase Polymerization Using the apparatus described in Example 1, a vapor phase polymerization was carried out in the following manner. 100 mg. of the above solid catalyst component, 2.5 mmol. of triethylaluminum and 0.5 mmol. of diethyldiethoxysilane were charged into the autoclave held at 60"C and polymerization was allowed to take place for 8 hours while propylene was fed continuously so as to maintain the total pressure at 8.5 kg/cm2G. As a result, there was prepared 450 g. of polypropylene of spherical particles having a bulk density of 0.40 and an average particle diameter of 980 ,um. Catalytic activity was 60,000g.polypropy- lene after extraction in boiling heptane was 90 wt.%.

Example 5 A 2 1 stainless steel autoclave equipped with an induction stirrer was purged with nitrogen and then charged with 1,000 ml. of hexane. 2.5 mmol. of triethylaluminum and 50 mg. of the solid catalyst component obtained in Example 1, then 0.25 mmol. of phenyltriethoxysilane was added and the temperature was raised to 50"C. Then, propylene was introduced up to a total pressure of 8.5 kg/cm2 G and polymerization was started, which was continued for 8 hours while maintaining the internal pressure of the autoclave at 8.5 kg/cm2G. Thereafter, the polymer slurry was transferred into a beaker arid hexane was removed under reduced pressure to yield 344 9. of polypropylene having a bulk density of 0.41 and an average particle diameter of 1,300 yam. Catalystic activity was 98,000g.polypropylene/g.Ti. The percent residue of the polypropylene after extraction in boiling heptane was 75 wt.%.

Example 6 (a) Preparation of Solid Catalyst Component 10 l of tetrahydrofuran, 500 g. of a reaction product obtained by ball-milling 1 kg.

anhydrous magnesium chloride and 420 g.

aluminum triethoxide, and 500 g. of silica (#952, a product of Fuji-Davison) which had been calcined at 600"C, were placed in a 30 1 stainless steel autoclave and reaction was allowed to take place at 60"C for 5 hours.

Thereafter, the reaction mixture was dried at 120"C under reduced pressure to remove tetrahydrofuran. Then, 5 1 of hexane was added, and after stirring, 100 ml. of tetraethoxysilane was added and reaction was allowed to take place for 5 hours under reflux of hexane to obtain a solid powder (A).

The solid powder (A) thus obtained was added into 3 l of titanium tetrachloride and reaction was allowed to take place at 120"C for 5 hours. Thereafter, the reaction mixture was washed with hexane until titanium tetrachloride was no longer detected in hexane, to obtain a solid catalyst component containing 70 mg. of titanium per gram thereof.

(b) Polymerization of Propylene in Vapor Phase A stainless steel autoclave was used as a vapor phase polymerization apparatus. Into the autoclave held at 60"C were charged 100 g. of the above solid catalyst component, 2.5 mol of triethyl-aluminum and 0.25 mol of phenyltriethoxysilane, and polymerization was allowed to take place for 6 minutes while propylene was fed continuously so as to maintain the total pressure at 4 kg/cm2G, to yield 5 kg. of polypropylene.

(c) Copolymerization of Ethylene and Propylene in Vapor Phase A stainless steel autoclave was used as a vapor phase polymerization apparatus, and a loop was formed by using a blower, a flow control valve and a dry cyclone for the separation of the resultant polymer. The temperature of the autoclave was controlled by passing warm water through its jacket.

Copolymerization was carried out at 60"C while feeding the polypropylene prepared in the above (b) into the autoclave at a rate of 5 grams per hour and while adjusting the concentrations (molar ratios) of ethylene, propylene and hydrogen fed into the autoclave by the blower to 44%, 44% and 12%, respectively.

As a result, there was obtained a copolymer of spherical particles having a melt index (MI) of 0.82, a bulk density of 0.40 and a density of 0.883 g/cm3. Thus, the density was very low, but the copolymer was free from stickiness. Catalytic activity was as high as 11 4,000g.coploymer/g.Ti. The polypropylene content of the copolymer was 0.62 wt.%.

After a continuous operation for 200 hours, the polymerization was stopped and the interior of the autoclave was inspected, but there was not recognized polymer adhesion to any of the inner wall, the agitator and the polymer withdrawing pipe, thus proving that a continuous operation can be attained extremely smoothly over along period of time.

Comparative Example 2 A solid catalyst component was prepared in the same way as in Example 6 except that the tetraethoxysilane was not used. Then, polymerization of propylene and copolymerization of ethylene and propylene were carried out in the same manner as in Example 6 except that the solid catalyst component just prepared was used and 0.5 mol of ethyl benzoate was used in place of the phenyltriethoxysilane.

After 30 hours, it became impossible to effect stirring, so the polymerization reaction was stopped and the interior of the autoclave was inspected. As a result, there was recognized a large amount of polymer adhesion to the inner wall and the agitator's blade and shaft. The melt index and density of the copolymer produced were 0.89 and 0.883 g/cm3, respectively. It is apparent that this comparative example is far inferior in continuous operability to Example 6 which employed tetraethoxysilane in the preparation of the solid catalyst component and both organoaluminum component and phenyltriethoxysilane in the polymer preparation.

Example 7 Using the solid catalyst component obtained in Example 6, polymerization of propylene was carried out in the same way as in (b) of Example 6 except that the amount of the phenyltriethoxysilane used and the polymerization time were changed to 0.5 mol and 1.5 minutes, respectively. As a result, 1 kg. of polypropylene was obtained.

Then, using the polypropylene just prepared above, copolymerization of ethylene and propylene was conducted in the same manner as in (c) of Example 6 except that the concentrations (molar ratios) of ethylene, propylene and hydrogen were adjusted to 38%, 56% and 6%, respectively. As a result, there was obtained a copolymer of spherical particles having a melt index of 0.32, a bulk density of 0.32 and a density of 0.875 g/cm3. Thus, the density was extremely low, but the copolymer was not sticky at all. Catalytic activity was as high as 100,0009. copolymer/g.Ti.

The propylene content of the copolymer was 0.14 wt.%.

After a continuous operation for 200 hours, the polymerization was stopped and the interior of the autoclave was inspected. As a result, there was not recognized polymer adhesion to any of the inner wall, the agitator's blade and the polymer withdrawing pipe.

Example 8 Using the solid catalyst component prepared in Example 6, polymerization of propylene was carried out in the same way as in (b) of Example 6 except that 0.2 mol of tetraethoxysilane was used in place of the phenyltriethoxysilane and the polymerization time was changed to 1.6 hours. As a result, 80 kg. of polypropylene was obtained.

Then, using the polypropylene just prepared above copolymerization of ethylene and propylene was conducted in the same manner as in (c) of Example 6. As a result, there was obtained a copolymer of spherical particles having a melt index of 0.70, a bulk density of 0.45 and a density of 0.888 g/cm3. Thus, the density was very low, but the copolymer was not sticky at all. Catalytic activity was as high as 107,000g.copolymer/g.Ti. The polypropylene content of the copolymer was 10.6 wt.%.

After a continuous operation for 200 hours, the polymerization was stopped and the interior of the autoclave was inspected. As a result, there was not recognized polymer adhesion to any of the inner wall, the agitator's blade and the polymer withdrawing pipe.

Example 9 Using the solid catalyst component prepared in Example 6, polymerization of propylene was carried out in the same way as in (b) of Example 6 except that the polymerization time was changed to 1.8 hours. As a result, 90 kg. of polypropylene was obtained.

Then, using the polypropylene just prepared above, copolymerization of ethylene and propylene was conducted in the same manner as in (c) of Example 6 except that hydrogen was not fed and the concentrations (molar ratios) of ethylene and propylene were adjusted to 25% and 75%, respectively. As a result, there was obtained a copolymer of spherical particles having a melt index of 0.1, a bulk density of 0.42 and a density of 0.898 g/cm3. Thus, the density was very low, but the copolymer was not sticky at all. Catalytic activity was as high as 103,000g.copolymer/g.Ti. The polypropylene content of the copolymer was 12.6 wt.%.

After a continuous operation for 200 hours, the polymerization was stopped and the interior of the autoclave was inspected. As a result, there was not recognized polymer adhesion to any of the inner wall, the agitator's blade and the polymer withdrawing pipe.

Example 10 Using the solid catalyst component prepared in Example 6, polymerization of propylene was carried out in the same way as in (b) of Example 6 except that the polymerization time was changed to 1 2 minutes. As a result, 10 kg. of polypropylene was obtained.

Then, using the polypropylene just prepared above, copolymerization was conducted in the same manner as in (c) of Example 6 except that butene-1 was used as a comonomer in place of propylene and the concentrations (molar ratios) of ethylene, butene-1 and hydrogen fed to the autoclave were adjusted to 44%, 44% and 12%, respectively. As a result, there was obtained a copolymer of spherical particles having a melt index of 1.0, a bulk density of 0.43 and a density of 0.880 g/cm3. Thus, the density was very low, but the copolymer was not sticky at all. Catalytic activity was as high as 103,000g.copolymer/g.Ti. The polypropylene content of the copolymer was 1.3 wt.%.

After a continuous operation for 200 hours, the polymerization was stopped and the interior of the autoclave was inspected. As a result, there was not recognized polymer adhesion to any of the inner wall, the agitator's blade and the polymer withdrawing pipe.

Example 11 (a) Preparation of Solid Catalyst Component 10 1 of tetrahydrofuran, 500 g. of a reaction product obtained by ball-milling 1 kg.

anhydrous magnesium chloride and 420 9.

aluminum triethoxide, and 500 g. of alumina (Ketjen B) which had been calcined at 600"C, were placed in a 30 I stainless steel autoclave and allowed to react at 60"C for 5 hours Thereafter, the reaction mixture was dried at 120"C under reduced pressure to remove tetrahydrofuran. Then, 51 of hexane was added, and after stirring, 100 ml. of tetraethoxysilane was added and reaction was allowed to take place for 5 hours under reflux of hexane to obtain a solid powder (B).

The solid powder (B) thus obtained was added into 3 l of titanium tetrachloride and reaction was allowed to take place at 120"C for 5 hours. Thereafter, the reaction mixture was washed with hexane until titanium tetrachloride was no longer detected in hexane, to obtain a solid catalyst component containing 60 mg. of titanium per gram thereof.

(b) Polymerization of Propylene in Vapor Phase A stainless steel autoclave was used as a vapor phase polymerization apparatus. Into the autoclave held at 60"C were charged 100 g. of the solid catalyst component prepared above, 2.5 mol of triethylaluminum and 0.25 mol of phenyltriethoxysilane, and polymerization was allowed to take place for 2 hours while propylene was fed continuously so as to maintain the total pressure at 4 kg/cm2G, to yield 100 kg. of polypropylene.

(c) Copolymerization of Ethylene and Propylene A stainless steel autoclave was used as a vapor phase polymerization apparatus, and a loop was formed by using a blower, a flow control valve and a dry cyclone for the separation of the resultant polymer. The temperature of the autoclave was adjusted by passing warm water through its jacket.

Copolymerization was carried out at 60"C while feeding the polypropylene prepared in the above (b) into the autoclave at a rate of 5 grams per hour and while adjusting the concentrations (molar ratios) of ethylene, propylene and hydrogen fed into the autoclave by the blower to 50%, 38% and 12%, respectively.

As a result, there was obtained a copolymer of spherical particles having a melt index of 0.50, a bulk density of 0.42 and a density of 0.890 g/cm3. Thus, the density was low, but the copolymer was not sticky at all. Catalytic activity was 1 03,000g.copolymer/g.Ti. The polypropylene content of the copolymer was 16.2 wt.%.

After a continuous operation for 200 hours, the polymerization was stopped and the interior of the autoclave was inspected. As a result, there was not recognized polymer adhesion to any of the inner wall, the agitator and the polymer withdrawing pipe, thus proving that a continuous operation can be done extremely smoothly over a long period of time.

Claims (8)

1. A process for preparing a polyolefin, characterized by polymerizing at least one olefin in the presence of a catalyst consisting essentially of: [lJ a solid catalyst component obtained by contacting and reacting the following components (1)---(4) with one another:: (1) a silicon oxide and/or an aluminum oxide, (2) a reaction product resulting from the reaction of a magnesium halide and a compound represented by the general formula Me(OR),X,~, wherein Me is an element selected from Groups I through Vlil of the Periodic Table, provided silicon, titanium and vanadium are excluded, R is a hydrocarbon radical having 1 to 24 carbon atoms, X is a halogen atom, z is the valence of Me and n is O < n (3) a compound represented by the general formula

wherein R1, R2 and R3 are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen or a halogen atom, R4 is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1=n=30, and (4) a titanium compound and/or a vanadium compound;; [Il] a compound represented by the general formula

wherein R1, R2 and R3 are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen or a halogen atom, R4 is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1=n=30; and [III] an organometallic compound.

2. The process of claim 1, wherein said olefin is an cu-olefin having 2 to 12 carbon atoms.

3. The process of claim 1, wherein said olefin is propylene and said polyolefin is polypropylene having a high stereospecificity.

4. The process of claim 1, characterized by comprising a first step in which a homopolymerization of propylene or a copolymerization of propylene and a small amount of other a-olefin is carried out using said catalyst, and a second step in which a copolymerization of ethylene and propylene and/or butene-1 is carried out in the presence of the polypropylene prepared in said first step in a substantially solvent-free condition, to obtain a soft copolymer having a density in the range of 0.860 to 0.910 g/cm3.

5. The process of claim 4, wherein 0.0001 to 80 weight percent of polypropylene based on the amount of the final copolymer obtained in said second step is prepared in said first step, and wherein the copolymerization in said second step is carried out in vapor phase.

6. A process as claimed in claim 1, substantially as hereinbefore described with particular reference to the Examples.

7. A process as claimed in claim 1, substantially as illustrated in any one of the Examples.

8. A polyolefin when prepared by the process claimed in any one of the preceding claims.