GB1580635A - Process for preparing -olefin polymers or copolymers - Google Patents

Description

(54) PROCESS FOR PREPARING a-OLEFIN POLYMERS OR COPOLYMERS (71) We, MITSUI PETROCHEMICAL INDUSTRIES LTD, a Japanese Body Corporate of 2-5, 3-chome, Kasumigaseki, Chiyoda-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an improved process for a preparing a-olefin polymers having improved stereoregularity and bulk density with improved catalytic activity by polymerizing at least one a-olefin containing at least 3 carbon atoms in two steps under specified conditions in the presence of a catalyst comprising (A) a solid titanium complex catalyst component (A) consisting essentially of magnesium, titanium, halogen and an electron donor, and (B) an organometallic compound of a metal of Groups I to III of Mendelejeff's Periodic Table.

It has been known that a catalyst comprising (A) a solid titanium complex, catalyst component (A) consisting essentially of magnesium, titanium, halogen and an electron donor and (B) an organometallic compound of a metal of Groups I to III of the Periodic Table is useful for preparing a-olefin polymers or copolymers having good stereoregularity with superior catalytic activity, and a number of suggestions have been made about the use of solid titanium complex catalyst components (A) prepared from various combinations of catalystforming components and/or under specified combinations of catalyst-forming combinations (for example, German Laid-Open Patent Publication No. 2230728 corresponding to Japanese Laid-open Patent Publication No. 16986/73 and French Patent 2143347; German Laid-Open Patent Publication No. 2347577 corresponding to Japanese Laid-Open Patent Publication No. 86482/74, British Patent 1, 435,768 and French Patent 2,200,290; German Laid-Open Patent Publication No. 2504036 corresponding to Japanese Laid-Open Patent Publications Nos. 108385/75 and 20297/76, and French Patent 2259842; German Laid Open Patent Publication No. 2553104 corresponding to Japanese Laid-Open Patent Publication No. 126590/75; Dutch Patent No. 7510394 corresponding to Japanese Laid-Open Patent Publication No. 28189/76 and French Patent 2283909; Japanese Laid-Open Patent Publication No. 57789/76; Japanese Laid-Open Patent Publication No. 64586/76; German Laid-Open Patent Publication No. 2605922 corresponding to Japanese Laid-Open Patent Publication No. 92885/76; Japanese Laid-Open Patent Publication No. 127185/76; and Japanese Laid-Open Patent Publication No. 136625/76).

However, there has been no positive suggestion about a two-step polymerization process using the catalyst component (A) because the two-step process is apparently disadvantageous over a one-step process in commercial operations and no benefit which would cancel such a disadvantage can be expected from the two-step process.

Some suggestions about the two-step polymerization of propylene with conventional titanium trichloride-type catalysts such as a titanium trichloride composition obtained by reducing titanium tetrachloride with metallic aluminium or other reducing agents have been known (for example, Japanese Patent Publication No. 32312/72, Japanese Patent Publication No. 14865/74, and British Patent 1359844 corresponding to Japanese Laid-Open Patent Publication No. 2439/72). It is well known however that in the polymerization of propylene utilizing these conventional titanium trichloride-type catalyst components which are different from the aforesaid catalyst component A, the use of high reaction temperatures in an attempt to increase polymerization activity reduces the crystallinity of the polymer, and conversely, the use of low reaction temperatures in an attempt to increase crystallinity inevitably results in the reduced polymerization activity of the catalyst. Hence, in considera tion of the balance between polymerization activity and crystallinity, temperatures of about 60 to about 70"C. are employed as most suitable for the polymerization of propylene. It is noted that when propylene is polymerized with these conventional titanium trichloride-type catalyst components at about 60 to 700 C., there is substantially no difference in result between a one-step polymerization process and a two-step polymerization process which involves a first step polymerization performed at low temperatures and a second-step polymerization performed at about 60 to 700C. Specifically, the amount of polymer formed per unit weight of catalyst per unit time is substantially the same for both processes, and in the case of a batchwise reaction, the proportion of a stereoregular polymer formed and the bulk density of the polymer are substantially the same for both, or is slightly higher in the two-step process. Accordingly, no substantial benefit of employing the two-step process at the sacrifice of the operating disadvantage is seen.

When the second step of the two-step polymerization process using the conventional titanium trichloride catalyst component is carried out at a temperature of more than about 80"C, the amount yielded of the polymer, the bulk density of the polymer, and the yield of a highly stereoregular polymer tends to decrease as shown, for example, by the experimental data in Japanese Patent Publication No. 14865/74 cited hereinabove. The use of such higher temperature is not practical.

The present invention provides a process for preparing an a-olefin polymer which comprises polymerizing at least one a-olefin containing at least 3 carbon atoms at a temperature of at least 20"C under an absolute pressure of 1 to 100 kg/cm2 in the presence of a catalyst comprising (A) a solid titanium complex catalyst component consisting essentially of magnesium, titanium, halogen and an electron donor, and OB) an organo-metallic compound of a metal of Groups I to III of Mendelejeff's Periodic Table, the polymerization being carried out in two steps: (a) a first step where at least 100 millimoles, per millimole of titanium atom, of an a-olefin is polymerized at a temperature of less than 50"C to form a polymer the amount of which is not more than 30%by weight based on the final product obtained in the second step, and (b) a second step where the final product is formed at a temperature higher than the temperature of the first step and from 50"C to 900C.

The process of the invention can be used to prepare homo-polymers of a-olefins containing at least 3 carbon atoms, co-polymers of at least two such a-olefins, copolymers of at least one such a-olefin with ethylene, preferably with up to 10 mole % of ethylene, or copolymers of at least one such a-olefin with a diene. The two-step polymerization process of the invention can achieve improved catalytic activity and provide polymers of improved stereoregularity and increased bulk density. These unexpected results cannot be anticipated from the results achieved by a two-step polymerization process using a conventional titanium trichloride catalyst.

It has thus been found that at polymerization temperatures of at least 700C, for example, more than 80"C, at which the amount of crystalline polypropylene normally tends to decrease, the reaction mixture can be prevented from becoming viscous as a result of an increase in the amount of amorphous polymer formed and a substantial decrease in the yield of the polymer can also be avoided.

The solid complex titanium component (A) suitably is obtained by intimately contacting a magnesium compound (or magnesium metal), a titanium compound and an electron donor by such means as heating or copulverization. The solid complex preferably has a halogen/titanium atomic ratio of more than 4:1, and does not substantially permit the liberation of a titanium compound when washed with hexane at room temperature (about 20"C). The chemical structure of this solid complex is not known, but presumably, ths magnesium atoms and the titanium atom are bonded firmly by, for example, having the halogen in common. The solid complex may, depending upon the method of preparation, contain another metal or metalloid atom such as aluminum, silicon, tin, boron, germanium, calcium and zinc, an electron donor, or an organic group ascribable thereto. It may further contain an organic or inorganic inert diluent, such as LiCl, CaCO3, Bawl2, Na2CO3, SrCl2, B2O3, Na2SO4, Awl203, SiO2, TiO2, Na2B407, Ca3(PO4)2, CaSO4, Al2(SO4)3, Cacti2, ZnCl2, polyethylene, polypropylene, and polystyrene. Preferably, the solid complex is one treated with an electron donor. In preferred examples of the solid complex titanium component (a), the halogen/titanium atomic ratio exceeds 4:1, preferably at least 5:1, more preferably at least 8: 1, and the magnesium/titanium atomic ratio is at least 3:1, preferably 5:1 to 50: 1, and the electron donor/titanium molar ratio of 0.2:1 to 6:1, preferably 0.4:1 to 3:1, more preferably 0.8:1 to 2:1. Furthermore, the specific surface area of the solid is at least 3 m2/g, preferably at least 40 m2/g, and more preferably at least 100 m2/g. It is also desirable that the X-ray spectrum of the solid complex (a) should show amorphous character irrespective of the starting magnesium compound, or is in a more amorphous state than ordinary commercially available grades of magnesium dihalide.

The solid titanium complex catalyst component (A) can be prepared by means knownper se. These means are disclosed, for example, in the prior patents cited hereinabove with regard to the utilization of solid titanium complex catalyst components (A), and also in Japanese Laid-Open Patent Publication Nos. 87489/77, 100596/77, 104593/77, 147688/77, 2580/78 and 151691/77.

Typical methods disclosed in these documents involve the reaction of at least a magnesium compound (or metallic magnesium), an electron donor and a titanium compound.

Examples of the electron donor are oxygen-containing electron donors such as water, alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, ethers, and acid amides, and nitrogen-containing electron donors such as ammonia, amines, nitriles, and isocyanates.

Specific examples of such electron donors include alcohols containing 1 to 18 carbon atoms such as methanol, ethanold, propanol, pentanol, hexanol, octanol, dodecanol, octadecyl alcohol, benzyl alcohol, phenylethyl alcohol, cumyl alcohol, and isopropyl benzyl alcohol; phenols containing 6 to 15 carbon atoms which may contain a lower alkyl group such as phenol, cresol, xylenol, ethyl phenol, propyl phenol, cumyl phenol, and naphthol; ketones containing 3 to 15 carbon atoms such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone and benzophenone; aldehydes containing 2 to 15 carbon atoms such as acetaldehyde, propionaldehyde, octyl aldehyde, benzaldehyde, tolualdehyde and naphthoaldehyde; organic acid esters containing 2 to 18 carbon atoms such as methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octyl acetate, cyclohexyl acetate, ethyl propionate, methyl butyrate, ethyl valerate, methyl chioroacetate, ethyl dichloroacetate, methyl methacrylate, ethyl crotonate, ethyl cyclohexanecarboxylate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, cyclohexyl benzoate, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate, amyl toluate, ethyl ethylbenzoate, methyl anisate, ethyl anisate, ethyl ethoxybenzoate, y-butyrolactone, y -valerolactone, coumarine, phthalide and ethylene carbonate; acid halides containing 2 to 15 carbon atoms such as acetyl chloride, benzyl chloride, toluic acid chloride, and anisic acid chloride; ethers containing 2 to 20 carbon atoms such as methyl ether, ethyl ether, isopropyl ether, butyl ether, amyl ether, tetrahydrofuran, anisole, and diphenyl ether; acid amides such as acetamide, benzamide and toluamide; amines such as methylamine, ethylamine, diethylamine, tributylamine, piperidine, tribenzylamine, aniline, pyridine, picoline and tetramethylethylene diamine; nitriles such as acetonitrile, benzonitrile and tolunitrile; and compounds of aluminum, silicon and tin which contain the aforesaid functional groups in the molecule. These electron donors can be used as a mixture of two or more.

Suitable magnesium compounds used for the formation of the solid complex titanium compound (A) are those containing halogen and/or organic groups. Specific examples of such magnesium compounds include magnesium dihalides, magnesium alkoxyhalides, magnesium aryloxyhalides, magnesium hydroxyhalides, magnesium dialkoxides, magnesium diaryloxides, magnesium alkoxyaryloxides, magnesium acyloxyhalides, magnesium alkylhalides, magnesium arylhalides, magnesium dialkyl compounds, magnesium diaryl compounds, and magnesium alkylalkoxides. The may be present in the form of adducts with the aforesaid electron donors. Or they may be double compounds containing other metals in metalloids such as aluminum, tin silicon, germanium, zinc or boron. For example, they may be double compounds of halides, alkyl compounds, alkoxyhalides, aryloxyhalides, alkoxides and aryloxides of metals such as aluminum, and the above-exemplified magnesium compounds. Or they may be double compounds in which phosphorus or boron is bonded to magnesium metal through oxygen. These magnesium compounds may be a mixture of two or more. Usually, the above-exemplified compounds can be expressed by simple chemical formulae, but sometimes, according to the method of preparation of the magnesium compounds, they cannot be expressed by simple formulae when they are usually regarded as mixtures of the compounds. For example, compounds obtained by a method which comprises reacting magnesium metal with an alcohol or phenol in the presence of a halosilane, phosphorus oxychloride, or thionyl chloride, and a method which comprises pyrolyzing Grignard reagents, or decomposing them with compounds having a hydroxyl group, a carbonyl group, an ester linkage or an ether linkage are considered to be mixtures of various compounds according to the amounts of the reagents or the degree of reaction. These mixtures can of course be used in this invention.

Various methods for producing the magnesium compounds exemplified hereinabove are known, and products of any of these methods can be used in this invention. Also, prior to use, the magnesium compound may be treated, for example, by a method which comprises dissolving it singly or together with another metal compound in ether or acetone, and then evaporating the solvent or putting the solution into an inert solvent thereby to separate the solid. A method can also be employed which involves pre-pulverizing mechanically at least one magnesium compound with or without anothec metal compound.

Preferred among these magnesium compounds are magnesium dihalides, aryloxyhalides and aryloxides, and double compounds of these with aluminum or silicon. More specifically, they are MgCl2, MgBr2, MgI2, MgF2, MgCl(OC6H5), Mg(OC6H5)2, MgCl(OC6H4-2-CH3), Mg(OC6H4-2-CH3)2, (MgC12),[Al(oR),C13-n]y, and (MgCl2)x[Si(OR)mCl4-m)y. In these formulae, R is a hydrocarbon group such as an alkyl or aryl group, and m or n R groups are the same or different, and 01 n 5 2, 0 ' m 0 < m 4, 4, and x and y are positive numbers. MgCl2 and its complexes or double compounds are especially preferred.

Suitable titanium compounds used for the formation of the solid complex titanium compound (A) are tetravelent titanium compounds of the formula Ti(OR) gX4-g wherein R is a hydrocarbon group, preferably an alkyl group containing 1 to 6 carbon atoms, X is a halogen atom, and g is 0 to 4. Examples of the titanium compounds are titanium tetrahalides such as Tics, TiBr4 or TiI4; alkoxytitanium trihalides such as Ti(OCH3)C13, Ti(OC2H5)Cl3, Ti(O n-C4H9)Cl3, Ti(OC2H5)Br3, and Ti(O iso-C4H9)Br3; alkoxy-titanium dihalides such as Ti(OCH3)2Cl2, Ti(OC2H5)2Cl2, Ti (O n-C4H9)2Cl2, and Ti(OC2H5)2Br2; trialkoxytitanium monohalides such as Ti(OCH3)3Cl, Ti(OC2H5)3Cl, Ti(O n-C4H9)3Cl and Ti(OC2H5)3Br; and tetraalkoxy-titanium such as Ti(OCH3)4, Ti(OC2H5)4, and Ti(O n-C4H9)4. Of these, the titanium tetrahalides are preferred, and especially preferred is titanium tetrachloride.

There are various examples of reacting the magnesium compound (or metallic magnesium), the electron donor and the titanium compound, to prepare the titanium complex catalyst component (A), and typical ones are described below.

[I] Method involving reacting the magnesium compound with the electron donor and then reacting the reaction mixture with the titanium compound: (I-a) Method [I] with the copulverization of the magnesium compound and the electron donor: - The electron donor added at the time of copulverization needs not to be in the free state, and may be present in the form of an adduct with the magnesium compound. At the time of copulverization, additional ingredients, which may be included in the complex titanium component (A), for example, the aforesaid organic or inorganic inert diluent, a halogenating agent such as a halogen compound of silicon, a silicon compound such as polysiloxane, and a compound of aluminum, germanium or tin, or a part of the titanium compound may be present together. Or the electron donor may be present in the form of an adduct (complex compound) with such a compound. The amount of the electron donor used is preferably about 0.005 to about 10 moles, more preferably about 0.01 to about 1 mole, per mole of the magnesium compound.

The copulverization may be carried out by using ordinary devices such as a rotary ball mill, a vibratory ball mill, and an impact mill. If the rotary ball mill is used, and 100 stainless stell (SUS 32) balls having a diameter of 15 mm are accomodated in a ball mill cylinder having an inner capacity of 800 ml and an inside diameter of 100 mm and made of stainless steel (SUS 32) and 20 to 40 g of the materials to be treated are put into it, it is advisable to perform the pulverization for at least 24 hours, preferably at least 48 hours at a rotating speed of 125 rpm.

The temperature of the pulverization treatment is usually room temperature (at least about 20"C) to 1000C.

The copulverized product can also be reacted with the titanium compound by copulverizing means. However, it is preferred to suspend the copulverized product in at least 0.05 mole, preferably 0.1 to 50 moles per mole of the magnesium compound, of a liquid titanium compound with or without an inert solvent in the absence of copulverization. The reaction temperature is from room temperature to 200"C., and the reaction time is from 5 minutes to 5 hours. The reaction can of course be performed under conditions outside those specified ranges. After the reaction, the reaction mixture is hot-filtered at a high temperature of, say, 60 to 1500C. to isolate the product which is then well washed with an inert solvent before use in polymerization.

(I-b) Method [I] without the copulverization of the magnesium compound and the electron donor: Usually, the magnesium compound is reacted with the electron donor in an inert solvent, or the magnesium compound is dissolved or suspended in the liquid electron donor for reaction.

It is possible to employ an embodiment in which magnesium metal is used as a starting material, and reacted with the electron donor while forming a magnesium compound.

The amount of the electron donor used is preferably 0.01 to 10 moles, more preferably 0.05 to 6 moles, per mole of the magnesium compound. The reaction proceeds sufficiently at a reaction temperature of from room temperatre to 200"C. for 5 minutes to 5 hours. After the reaction, the reaction mixture was filtered or evaporated, and washed with an inert solvent to isoloate the product. The reaction of the reaction product with the titanium compound can be performed in the same way as described in (I-a).

(I-c) Method which comprises reacting the reaction product between the magnesium compound and the electron donor with a compound selected from organoaluminum com pounds, silicon compounds and tin compounds, and then reacting the resulting product further with the titanium compound: This method is a special embodiment of the method (I-b). Generally, complexes obtained by the method (I-a) have superior properties, but some of complexes obtained by the method (I-b) have inferior properties to those obtained by method (I-a). The properties of such complexes can be very effectively improved by the performance of method (I-c) in which the organoaluminum compound, silicon compound or tin compound is reacted prior to the reaction with the titanium compound.

Examples of the organoaluminum compounds that can be used in this method are trialkyl aluminums, dialkyl aluminum hydrides, dialkyl aluminum halides, alkyl aluminum sesquihalides, alkyl aluminum dihalides, dialkyl aluminum alkoxides or phenoxides, alkyl aluminum alkoxy halides or phenoxyhalides, and mixtures of these. Of these, the dialkyl aluminum halides, alkyl aluminum susquihalides, alkyl aluminum dihalides, and mixtures of these are preferred. Specific examples of these include triethyl aluminum, triisobutyl aluminum, diethyl aluminum hydride, dibutyl aluminum hydride, diethyl aluminum chloride, diisobutyl aluminum bromide, ethyl aluminum sesquichloride, diethyl aluminum ethoxide, ethyl aluminum ethoxy chloride, ethyl aluminum dichloride, and butyl aluminum dichloridde.

The silicon or tin compounds, for example silicon or tin halogen compounds or organic compounds, are compounds containing at least one halogen or hydrocarbon group directly bonded to silicon or tin, and may further containing hydrogen, an alkoxy group, a phenoxy group, or the like. Specific examples include, silicon tetrahalides, tetraalkyl silicons, silicon alkyl halides, silicon alkylhydrides, tin tetrahalides, tin alkylhalides, and tin hydride halides.

Of these, silicon tetrachloride and tin tetrachloride are preferred.

The reaction of the resulting reaction product between the magnesium compound and the electron donor with the organoaluminum compound, silicon compound or tin compound may be carried out in an inert solvent. Such a compound is used in an amount of preferably 0.1 to 20 moles, more preferably 0.5 to 10 moles, per mole of the magnesium compound. The reaction is carried out preferably at a temperature of from room temperature to 1000C. for 5 minutes to 5 hours. After the reaction, the reaction mixture is preferably well washed with an inert solvent and then reacted with the titanium compound. The reaction of this reaction product with the titanium compound can be performed in accordance with the method described in (I-a).

[II] Method which comprises simultaneously reacting the magnesium compound, the electron donor and the titanium compound.

[III] Method which comprises reacting the reaction product between the titanium compound and the electron donor with the magnesium compound.

The reactions in the methods [II] and [III] are preferably performed by copulverization.

The pulverization conditions and the proportions of the raw materials are the same as set forth under method tI]. In these methods, however, it is not preferred to use a large quantity of the titanium compound. The amount of the titanium compound is preferably 0.01 to 1 mole per mole of the magnesium compound.

The above methods are typical methods, and many modifications are possible as shown below.

(1) Method [I] in which the electron donor is caused to be present when reacting the titanium compound.

(2) A method in which the organic or inorganic inert diluent and the silicon. aluminum, germanium or tin compound are caused to be present during the reaction; a method in which these compounds are caused to act before the reaction; a method in which these compounds are caused to act between the reactions; a method in which these compounds are caused to act after the reaction. A typical example of methods is the method (I-c). These reagents can be used at desired points in the above methods. For example, (2-a) Method in which a halogenating agent such as SiCl4 is caused to act on the compound obtained by methods [It, [II] and [III].

3 Method in which the titanium compound is caused to act two or more times.

(3-a) The method in which the titanium compound and the electron donor are reacted with the reaction product obtained by any of the methods [I] to [III].

(3-b) The method in which the titanium compound, the organoaluminum compound and the electron donor are reacted with the reaction product of any one of these methods [I] to [III].

A number of other modifications can be made by changing the order of addition of reaction agents, or by carrying out a plurality of reactions, or by using additional reaction agents. In any of such methods, it is desirable that the halogen, titanium and magnesium in the complex (A), the proportion of the electron donor, the surface area of the complex (A) and the X-ray spectrum of the catalyst be within the above range or in the above-mentioned conditions.

Examples of the electron donor to be desirably included in the catalyst component (A) are esters, ethers, ketones, tertiary amines, acid halides, and acid anhydrides, which do not contain active hydrogen. Organic acid esters and ethers are especially preferred, and most preferred are aromatic-carboxylic acid esters and alkyl-containing ethers. Typical examples of suitable aromatic carboxylic acid esters include lower alkyl esters such as lower alkyl esters of benzoic acid, and lower alkyl esters of alkoxy benzoic acid. The term "lower" means the possession of 1 to 4 carbon atoms. Those having 1 or 2 carbon atoms are especially preferred.

Suitable alkyl-containing ethers are those containing 4 to 20 carbon atoms such as diisoamyl ether and dibutyl ether.

The organometallic compound (B) has a hydrocarbon group directly bonded to the metal, and includes, for example, alkyl aluminum compounds, alkyl aluminum alkoxides, alkyl aluminum hydrides, alkyl aluminum halides, dialkyl zincs, and dialkyl magnesiums. Preferred among them are the organoaluminum compounds. Specific examples of the organoaluminum compounds are trialkyl or trialkenyl aluminums such as Al(C2H5)3, A1(CH3)3, A1(C3H7)3, Al(C4H9)3 and Al(C12H25)3; alkyl aluminum compounds having such a structure that many aluminum atoms are connected through oxygen or nitrogen atoms, such as (C2H 5) 2Al0Al(C2Hs)2, (C4H9)2AlOAl(C4H9)2, and (C2Hs)2 AlhAl(C2Hs)2; C6Hs, dialkyl aluminum hydrides such as (C2Hs)2AIH or (C4H9)2AlH; dialkyl aluminum halides such as (C2H5)2 A1C1, (C2H5)2AlI or (C4H9)2AlCl; and dialkyl aluminum alkoxides or phenoxides such as (C2Hs)2Al(OC2Hs) and (C2Hs)2Al(OC6Hs). Of these, the trialkyl aluminums are most preferred.

Preferably, the organometallic compound (B) is used together with an electron donor (C), for example those examplified hereinabove with regard to the catalyst component (A).

Above all, it is used preferably together with an organic acid ester, especially an aromatic carboxylic acid ester containing 8 to 18 carbon atoms such as methyl benzoate, ethyl benzoate, methyl p-toluate, ethyl p-toluate, methyl p-anisate, and ethyl p-anisate. Such an organic carboxylic acid ester serves to maintain the yield of a highly stereoregular polymer at a high level even when the polymerization is performed in the presence of hydrogen.

The titanium complex catalyst component (A), the organometallic compound (B) and the electron donor (C) preferably the organic carboxylic acid may be mixed in any desired order.

The suitable amount of the free organic carboxylic acid ester is not more than 1 mole, preferalby 0.01 to 0.5 mole, per metal atom of the organometallic compound.

According to the process of this invention, a-olefins containing at least 3 carbon atoms are polymerized under specified conditions in the presence of a catalyst comprising (A) the solid titanium complex catalyst component consisting essentially of magnesium, titanium, halogen and an electron donor and (B) the organometallic compound of a metal of Groups I to III of the Periodic Table with or without (C) the electron donor.

The first-step polymerization temperature is not more than 50"C. However, in view of the removal of the heat of polymerization or the ra tion. As a comonomer, up to 10 mole % of ethylene may be used. Dienes may also be used as comonomers.

In the conventional copolymerization of propylene with ethylene, the bulk density of the polymer tends to decrease abruptly with increasing ethylene content in a one-step process.

However, the two-step process of this invention makes it possible to afford a polymer having a high bulk density. In homopolymerization, too, an improvement is achieved in bulk density and the ratio of a stereoregular polymer formed, and a marked increase is observed in the amount yielded of polymer per unit weight of the catalyst per unit time. No clear reason can be assigned to the unexpected result of increased catalytic activity, but it is presumed that this is a unique feature of the catalyst used in this invention.

The following Examples Illustrate the present invention in more details. In the Examples the pressures are gauge pressures.

Example 1 Preparation of catalyst (component A) Commercially available anhydrous magnesium chloride (20 g), 6.0 ml of ethyl benzoate and 3.0 ml of silicon tetrachloride were charged under an atmosphere of nitrogen into a stainless steel (SUS 32) ball mill cylinder having an inner capacity of 800 ml and an inside diameter of 100 mm and containing 100 stainless steel (SUS 32) balls with a diameter of 15 mm accomodated therein, and were contacted with one another at 125 rpm for 48 hours.

The solid product obtained by the treatment was suspended in 150 ml of titanium tetrachloride. The solid matter was collected by filtration, and washed with purified hexane until no free titanium tetrachloride was detected in the wash liquid, to afford component (A) which contained, as atoms, 1.6% by weight of titanium, 64.0% by weight of chloride, and 8.9% by weight of ethyl benzoate.

Polymerization An autoclave having an available volume of 2 liters was charged with 1.0 liter of kerosene 1.8 millimoles of triethyl aluminum, 0.6 millimole of ethyl benzoate, and 0.1 millimole, calculated as titanium atom, of the catalyst component A set forth above. Hydrogen (250 mp was added, and while feeding propylene, the system was maintained at 400 C. and 4 kg/cm G for 10 minutes. In this manner, about 40 g of propylene was polymerized. Then, over the course of about 20 minutes the temperature of this system was raised to 60"C., and propylene was continuously fed and polymerized for 20 hours at 7.0 kg/cm2.G. The solid matter was collected by filtration, washed with hexane, and dried to afford 486 g of polypropylene as a white powder. The powdery polypropylene had a boiling n-heptane extraction residue of 96.4%, a bulk density of 0.42 g/cc, and an [71] of 2.9. On the other hand, concentrating the liquid layer afforded 14.3 g of a soluble polymer.

Examples 2 and 3 Propylene was polymerized using the same catalyst and polymerization procedure as in Example 1 except that the amount of propylene polymerized in the first step was changed as shown in Table 1. The results are also shown in Table 1.

Table 1 Example Amount Polymeri- Amount Boiling Amount [ri] Bulk of zation of n-heptane of density propylene time in polymer residue soluble (g/cc) fed in the first finally (S0) polymer the first step obtained step (minutes) (g) (g) 2 10 3 474 95.2 12.5 2.7 0.42 3 125 40 536 95.6 14.7 2.9 0.43 Example 4 Propylene was polymerized using the same catalyst and polymerization procedure as in Example 1 except that the polymerization in the second step was carried out at 70"C., and the amount of hydrogen added was changed to 150 ml. There was obtained 523 g of polypropylene as a powder which had a boiling n-heptane extraction residue of 95.8%, a bulk density of 0.38 g/cc, and an [71] of 2.6.

Concentrating the liquid layer afforded 17.3 g of a soluble polymer.

Comparative Examples 1 and 2 Propylene was polymerized for 2.5 hours at 60"C. and 70 C. respectively using the same catalyst and polymerization procedure as in Example 1 except that the first step was omitted.

The amount of hydrogen added was changed to 1500 C. when the temperature was 70"C. The results are shown in Table 2 together with the results of Example 1.

Table 2 Comparative Polymerization Polypropylene Boiling Soluble Bulk [i] Example temperature powder n-heptane polymer density ( C) (g) extraction (g) (g/cc) residue (S0) 1 60 412 92.2 16.3 0.37 2.6 2 70 422 91.3 17.4 0.33 2.6 Example 1 - 486 96.4 14.3 0.42 2.9 The results show that when the first step was performed, an apparent increase in bulk density and stereoregularity was achieved as compared with the case of omitting the first step, and unexpectedly, the amount of the polymer formed per unit weight of the catalyst increased markedly. This is an evident effect of the first-step treatment.

Comparative Example 3 This example illustrates the first-step polymerization performed with a conventional titanium trichloride-type catalyst.

Polymerization An autoclave having an available volume of 2 liters was charged with 1.0 liter of kerosene, 6.0 millimoles of diethyl aluminum chloride, and 2.0 millimoles of titanium trichloride (AA grade). Hydrogen (400 ml) was added, and about 27 g of propylene was polymerized while feeding propylene for 20 minutes at 400C. and 4 kg/cm .G.

Then, over the course of 20 minutes, the temperature of the system was raised to 70"C., and propylene was continuously fed and polymerized for 4.0 hours at 7.0 kg/cm2. G..

For comparison, the polymerization was performed at 700C. for 4 hours and 40 minutes without performing the first-step polymerization. The results are shown in Table 3.

Table 3 Performance Polypropylene Boiling Soluble Bulk [rlf of the powder n-heptane polymer density first step (g) extraction (g) Kg/cc) residue {S0) No 452 97.1 52.0 0.37 2.9 Yes 436 96.5 41.4 0.39 3.0 The results show that a slight effect of the first-step polymerization was observed on an increase in bulk density and stereoregularity. However, the effect was far smaller than the effect on the supported titanium tetrachloride-type catalyst, and it is seen that the effect of the first step is substantially not observed with the conventional catalyst. A comparison of Table 2 with Table 3 shows that the use of the two-step procedure exhibits a unique effect on the catalyst containing a titanium catalyst component.

Example 5 This example illustrates the effect of the first-step polymerization on the random copolymerization of propylene and ethylene in the presence of the catalyst shown in Table 1.

Polymerization An autoclave having an available volume of 2 liters was charged with 1.0 liter of kerosene, 1.8 millimoles of triethyl aluminum, 0.42 millimole of ethyl benzoate, and 0.1 millimole, calculated as titanium atom, of the catalyst component A obtained in Example 1. Hydrogen (150 ml) was added, and about 15 g of propylene was polymerized while feeding propylene at 40"C. and 2 kg/cm2.G for 10 minutes.

Then, over the course of 20 minutes, the temperature of the system was raised to 600C., and propylene gas containing 5.7 mole% of ethylene was continuously fed, and polymerized for 2 hourse at 5.0 kg/cm2.G.

For comparison, propylene gas containing 5.9 mole% of ethylene was continuously fed, and polymerized at 60"C. for 2.5 hours without performing the first-step polymerization at 40"C.

The results are shown in Table 4.

Table 4 Performance Powdery Soluble Bulk [r of the first copolymer polymer density step (g) (g) (g/cc) No (comparison) 299 57 0.27 2.7 Yes 482 58 0.34 2.6 (invention) 482 58 0.34 2.6 The results shown that the ratio of the soluble polymer to the powdery copolymer was smaller and the bulk density of the polymer is higher in the case of performing the first step than in the case of omitting the first step. The effect was greater than in the case of homo-polymerization.

Example 6 Preparation of the catalyst component A Commercially available anhydrous magnesium chloride (0.1 mole) was suspended in 0.3 liter of kerosene, and 0.4 mole of ethanol and 0.1 mole of ethyl benzoate were added to the suspension at room temperature. Then 0.3 mole of diethyl aluminum chloride was added at room temperature, and the mixture was stirred for 1 hour. The solid portion of the product was collected, washed sufficiently with kerosene, suspended in 0.3 liter of kerosene solution containing 30 ml of titanium tetrachloride, and reacted at 800C for 2 hours. After the reaction, the supernatant liquid was removed by decantion, and the solid portion was washed thoroughly with fresh kerosene. The resulting solid contained, on the basis of atom, 423 mg of titanium, 582 mg of chlorine and 132 mg of ethyl benzoate.

Polymerization An autoclave having an available volume of 2 liters was charged with 1.0 liter of kerosene 1.6 millimoles of triethyl aluminum and 0.5 millimole of ethyl benzoate, and 0.07 millimole, calculated as titanium atom, of the catalyst component A prepared above. Hydrogen (250 ml) was added, and about 35 g of propylene was polymerized while feeding propylene at 40"C. and 4 kg/cm2.G for 10 minutes.

Then, over the course of 20 minutes, the temperature. of the polymerization system was raised to 60"C., and propylene was continuously fed and polymerized for 2.0 hours at 7.0 kg/cm2.G.

For comparison, the above polymerization was performed in one step at 600C for 25 hours without the first-step polymerization at 40"C.

The results are shown in Table 5.

Table 5 Performance Polypropylene Boiling Soluble Bulk [rg of the first powder n-heptane polymer density step (g) extraction (g) (g/cc) residue (S0) Yes (invention) 525 96.2 23.3 0.38 2.7 No (comparison) 382 92.0 16.0 0.32 2.5 Example 7 Preparation of the catalyst component A.

Ten grams of the catalyst obtained by the catalyst preparation method of Example 1 was suspended in 150 ml of kerosene, and with stirring, 3.4 millimoles of triethyl aluminum, 13.6 millimoles of ethyl benzoate, and 3.4 millimoles of titanium tetrachloride were added successively at one-hour intervals. After the reaction, the solid portion of the product was collected by filtration, washed thoroughly with purified n-hexane, and dried to afford a catalyst component A which contained, as atoms, 2.2% by weight of titanium, 60.0% by weight of chlorine, and 10.8% by weight of ethyl benzoate.

Polymerization The polymerization of Example 6 was repeated except that 2.0 millimoles of triethyl aluminum, 1.8 millimoles of ethyl benzoate, and 0.20 millimole, calculated as titanium atom, of the catalyst component A were added.

For comparison, the above polymerization was performed in the same way as in Example 6 except that the first step was omitted, and the polymerization time was changed to 2.5 hours.

The results are shown in Table 6.

Table 6 Performance Polypropylene Boiling Soluble Bulk [7?] of the first powder n-heptane polymer density step extraction (g) (g/cc) (g) residue (g) Yes 537 97.0 27.7 0.44 3.0 No 364 92.8 11.4 0.38 2.9 Example 8 Preparation of catalyst component A Commercially available anhydrous magnesium chloride (20 g), 5.3 g of n-butyl benzoate and 2.3 g of p-cresol were charged into a stainless steel (SUS 32) ball mill having an inside diameter of 100 mm and an inner capacity of 0.8 liter and including 2.8 kg of stainless steel (SUS 32) balls with a diameter of 15 mm in a nitrogen atmosphere, and co-pulverized for 24 hours at an impact acceleration of 7G. The resulting co-pulverized product (10 g) was suspended in 100 ml of titanium tetrachloride, and after elevating the temperature of the suspension to 100DC., it was stirred for 2 hours. Them the solid was collected by hot filtration, washed with kerosene and hexane, and dried to afford a titanium-containing solid catalyst component which contained 2.8% by weight of titanium, 61.0% by weight of chlorine and 20.0% by weight of magnesium.

Polymerization The inside of a 2-liter autoclave was purged with propylene, and then it was charged with 750 ml of hexane deprived fully of oxygen and moisture, 3.75 millimoles of triisobutyl aluminum, 1.25 millimoles of ethyl p-toluate, and 38 mg of the solid catalyst component prepared as above. They were stirred for 5 minutes at 35"C., and about 10 g of propylene was polymerized in the first step. Then, the polymerization system was heated to 55"C. over the course of about 5 minutes, and a propylene gas containing 6.2 mole% of ethylene was continuously fed, and polymerized for 2.0 hours at 2.5 kg/cm2.G. The results are shown in Table 7.

Example 9 Preparation of a catalyst component (A) A nitrogen-purged glask was charged with 50 ml of toluene and 12 ml of silicon tetrachloride, and 50 ml of a normal butyl ether solution containing 0.05 mole of n-butyl magnesium chloride was added dropwise to the mixture at 100C. over the course of 2 hours. After the addition, the temperature of the mixture was raised to 600 C., and stirred at this temperature for 2 hours. The solid matter was collected by filtration, fully washed with hexane, and dried.

The powdery solid was suspended in 50 ml of kerosene, and 1.1 g of ethyl o-toluate and 0.8 g of ethyl cyclohexane-carboxylate were added. The mixture was stirred at 800C. for 2 hours.

The supernatant was removed by decantation, and decantation was further carried out using fresh solvent until complete washing was effected. Titanium tetrachloride (100 ml) was added to 30 ml of the suspension containing a solid. The mixture was heated to 110 C., and then stirred for 2 hours. The supernatant was removed by decantation, and 100 ml of titanium tetrachloride was further added. The mixture was stirred at 1300C. for 2 hours, and the solid matter was collected by hot filtration. It was fully washed with hot kerosene and hexane, and dried to afford a catlyst component (A) which contained, as atoms, 1.5% by weight of titanium, 68.0% by weight of chlorine, and 22.0% by weight of magnesium.

Polymerization A propylene gas containing ethylene was polymerized under the same conditions as in Example 8 except that tri-n-hexyl aluminum was used instead of triisobutyl aluminum, ethyl p-anisate was used instead of the ethyl p-toluate, and 67 mg of the solid catalyst component prepared as above was used. The results are shown in Table 7.

Example 10 Preparation of a catalyst component (A) A reactor was charged with 50 ml of a butyl ether solution containing 0.05 mole of n-butyl magnesium chloride in an atmosphere of nitrogen, and 0.05 mole of 2,6-dimethyl phenol was added dropwise. The mixture was heated to 700 C., and stirred for 2 hours. The butyl ether was removed by decantation, and 50 ml of purified kerosene was added. Furthermore, 0.01 mole of ethyl p-anisate was added dropwise. The mixture was heated to 80"C., and stirred for 2 house at this temperature. The solid portion was collected by filtration, washed with purified hexane, and dried under reduced pressure. The resulting product was suspended in 100 ml of titanium tetrachloride, and with stirring, reacted for 2 hours at 1000C. The supernatant was removed by decantation, and 100 ml of titanium tetrachloride was added.

The mixture was stirred for 2 hours at 1000C., and the solid portion was collected by hot filteration. The solid portion was fully washed with purified hexane, and dried under reduced pressure to afford a titanium-containing solid catalyst component which contained 2.9% by weight of titanium. 59.0% by weight of chlorine, and 19.0% by weight of magnesium.

Polymerization A 2-liter autoclave was charged with 750 ml of hexane deprived of oxygen and moisture.

While passing a propylene gas containg 7.39 mole % of ethylene, 3.75 millimoles of an organoaluminum compound having an average composition ET2.9Al(OEt)0.1, 1.25 millimoles of methyl p-toluate and 37 mg of the solid catalyst component prepared as above were charged. The autoclave was sealed, and 0.2 litres of H2 at N.T.P. was introduced. The contents were stirred at 35"C for 5 minutes to polymerize 12 g of the propylene gas. Analysis showed that the polymer thus formed in the first step contained 2.1 mole % of ethylene. The polymerization system was then heated to 60"C. over the course of about 7 minutes. A propylene gas containing 7.39 mole% of ethylene was continuously fed, and polymerized for 2.0 hours at a total pressure of 2.5 kg/cm .G. The results are shown in Table 7.

Example 11 Preparation of a catalyst component A Magnesium diphenoxide was synthesized by the reaction of commercially available Mg(OCH3)2 with phenol. A stainless steel ball mill cylinder having an inner capacity of 0.8 liter and an inside diameter of 100 mm and including 2.8 kg of stainless steel (SUS 32) balls with a diameter of 15 mm was charged with 0.2 mole of magnesium diphenoxide and 0.033 mole of n-octyl benzoate in an atmosphere of nitrogen, and they were co-pulverized for 24 hours at an impact acceleration of 7G. The resulting solid product was suspended in 200 ml of titanium tetrachloride, and the suspension was stirred at 1000C. for 2 hours. Then, the solid portion was collected by hot filtration, washed fully with hexane, and dried to afford a titanium-containing solid catalyst component containing 2.8% by weight of titanium, 60.0% by weight of chlorine and 21.0% by weight of magnesium.

Polymerization A propylene gas containing ethylene was polymerized under the same conditions as in Example 10 except that 37 mg of the titanium-containing solid catalyst component prepared as above was used, 3.75 millimoles of the organoaluminum compound having an average composition Et.2-9AlH- was used instead of the compound Et2.9Al(OEt)0.1, and the amount of the propylene gas polymerized in the first step was 15 g. The results are shown in Table 7.

Example 12 Polymerization Into a 2-liter autoclave were charged 3.75 millimoles of diethyl aluminum chloride, 3.75 millimoles of n-butyl magnesium chloride synthesized in kerosene, 1.25 millimoles of methyl p-toluate, and 37 mg of the titanium-containing solid catalyst component prepared in Example 11 in the order stated in an atmosphere of propylene. The autoclave was sealed, and 0.2 litres of H2 at N.T.P. was charged. By stirring the contents at 35"C for 5 minutes, 9 g of the propylene gas was polymerized in the first step. The polymerization system was heated to 60"C. over the course of 5 minutes. A propylene gas containing 6.58 mole% of ethylene was continuously fed, and polymerized at 60"C. and 2.5 kg/cm2. G for 2 hours. The results are shown in Table 7.

Table 7 Example Powdery Soluble Bulk Melt copolymer polymer density index (g) (g) (g/cc) 8 98.7 7.9 0.29 14.6 9 96.4 7.9 0.30 24.5 10 175.0 13.9 0.29 16.2 11 141.8 15.3 0.30 14.9 12 128.9 9.6 0.30 5.5 WHAT WE CLAIM IS: 1. A process for preparing an a-olefin polymer which comprises polymerizing at least one a-olefin containing at least 3 carbon atoms at a temperature of at least 200C under an

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   100 ml of titanium tetrachloride, and with stirring, reacted for 2 hours at 1000C. The supernatant was removed by decantation, and 100 ml of titanium tetrachloride was added.

   The mixture was stirred for 2 hours at 1000C., and the solid portion was collected by hot filteration. The solid portion was fully washed with purified hexane, and dried under reduced pressure to afford a titanium-containing solid catalyst component which contained 2.9% by weight of titanium. 59.0% by weight of chlorine, and 19.0% by weight of magnesium.

   Polymerization A 2-liter autoclave was charged with 750 ml of hexane deprived of oxygen and moisture.

   While passing a propylene gas containg 7.39 mole % of ethylene, 3.75 millimoles of an organoaluminum compound having an average composition ET2.9Al(OEt)0.1, 1.25 millimoles of methyl p-toluate and 37 mg of the solid catalyst component prepared as above were charged. The autoclave was sealed, and 0.2 litres of H2 at N.T.P. was introduced. The contents were stirred at 35"C for 5 minutes to polymerize 12 g of the propylene gas. Analysis showed that the polymer thus formed in the first step contained 2.1 mole % of ethylene. The polymerization system was then heated to 60"C. over the course of about 7 minutes. A propylene gas containing 7.39 mole% of ethylene was continuously fed, and polymerized for 2.0 hours at a total pressure of 2.5 kg/cm .G. The results are shown in Table 7.

   Example 11 Preparation of a catalyst component A Magnesium diphenoxide was synthesized by the reaction of commercially available Mg(OCH3)2 with phenol. A stainless steel ball mill cylinder having an inner capacity of 0.8 liter and an inside diameter of 100 mm and including 2.8 kg of stainless steel (SUS 32) balls with a diameter of 15 mm was charged with 0.2 mole of magnesium diphenoxide and 0.033 mole of n-octyl benzoate in an atmosphere of nitrogen, and they were co-pulverized for 24 hours at an impact acceleration of 7G. The resulting solid product was suspended in 200 ml of titanium tetrachloride, and the suspension was stirred at 1000C. for 2 hours. Then, the solid portion was collected by hot filtration, washed fully with hexane, and dried to afford a titanium-containing solid catalyst component containing 2.8% by weight of titanium, 60.0% by weight of chlorine and 21.0% by weight of magnesium.

   Polymerization A propylene gas containing ethylene was polymerized under the same conditions as in Example 10 except that 37 mg of the titanium-containing solid catalyst component prepared as above was used, 3.75 millimoles of the organoaluminum compound having an average composition Et.2-9AlH- was used instead of the compound Et2.9Al(OEt)0.1, and the amount of the propylene gas polymerized in the first step was 15 g. The results are shown in Table 7.

   Example 12 Polymerization Into a 2-liter autoclave were charged 3.75 millimoles of diethyl aluminum chloride, 3.75 millimoles of n-butyl magnesium chloride synthesized in kerosene, 1.25 millimoles of methyl p-toluate, and 37 mg of the titanium-containing solid catalyst component prepared in Example 11 in the order stated in an atmosphere of propylene. The autoclave was sealed, and 0.2 litres of H2 at N.T.P. was charged. By stirring the contents at 35"C for 5 minutes, 9 g of the propylene gas was polymerized in the first step. The polymerization system was heated to 60"C. over the course of 5 minutes. A propylene gas containing 6.58 mole% of ethylene was continuously fed, and polymerized at 60"C. and 2.5 kg/cm2. G for 2 hours. The results are shown in Table 7.

   Table 7 Example Powdery Soluble Bulk Melt copolymer polymer density index (g) (g) (g/cc)

   8 98.7 7.9 0.29 14.6

   9 96.4 7.9 0.30 24.5

   10 175.0 13.9 0.29 16.2

   11 141.8 15.3 0.30 14.9

   12 128.9 9.6 0.30 5.5 WHAT WE CLAIM IS: 1. A process for preparing an a-olefin polymer which comprises polymerizing at least one a-olefin containing at least 3 carbon atoms at a temperature of at least 200C under an

   absolute pressure of of 1 to 100 kg/cmz in the presence of a catalyst comprising (A) a solid titanium complex catalyst component consisting essentially of magnesium, titanium halogen and an electron donor, and (B) an organometailic compound of a metal of Groups I to III of M-endelejeff's Periodic Table, the polymerization being carried out in two steps: (a) a first step where at least 100 millimoles, per millimole of titanium atom, of an a-olefin is polymerized at a temperature of less than 509C to form a polymer the amount of which is not more than 30% by weight based on the final product obtained in the second step, and (b) a second step where the final product is formed at a temperature higher than the teinperature of the'first step ahd from 500C to 90"C.

   2. A process according to claim 1; wherein the halogen/titanium atomic ratio of component (A) exceeds 4:1, and when component (A) is washed with hexane at about 20 C, titanium is not substantially removed from it.

   3. A process according'to claim 1 or 2, wherein the magnesium/titanium atomic ratio it least 3:1.

   4. A process according to any one of the preceding claims, wherein the electron donor/titanium mole ratio of component (A) is 0.2:1 to 6:1.

   5. A process according to any one of the preceding claims, wherein the electron donor is a ketone containing 3 to 15 carbon atoms, an aldehyde containing 2 to 15 carbon atoms, an organic acid ester containing 2 to 18 carbon atoms, an acid halide containing 2 to 15 carbon atoms, an ether containing 2 to 20 carbon atoms, an acid amide, an amine or a nitrile.

   6. A process according to any one of the preceding claims, wherein the polymerization is carried out in the presence also of a free electron donor (C).

   7. A process according to claim 6, wherein the free electron donor(C) is an organic acid ester containing 2 to 18 carbon atoms.

   8. 'A process according to any one of the preceding claims, wherein component (B) is an organoaluminium compound.

   9. A process according to any one of the preceding claims, wherein the temperature of the second step is at least 10 C higher than the first-step temperature and is from 60 C to 80"C.

   .10. A process according to claim 1 substantially as described in any one of the Examples, 11. An a-olefin polymer when prepared by a process as claimed in any one of the preceding claims.