GB2049709A

GB2049709A - A Process for Preparing an Olefin Polymer

Info

Publication number: GB2049709A
Application number: GB8009852A
Authority: GB
Original assignee: Mitsubishi Petrochemical Co Ltd
Current assignee: Mitsubishi Petrochemical Co Ltd
Priority date: 1979-03-24
Filing date: 1980-03-24
Publication date: 1980-12-31
Also published as: GB2049709B; FR2452498B1; FR2452498A1; DE3011326A1

Abstract

In a process for preparing an olefin polymer by a polymerization reaction, the olefin is contacted with a catalyst comprising:- (1) a solid catalyst component composed of a magnesium halide, a titanium halogen compound and an electron donor support on a metal oxide carrier containing silica, alumina, magnesia, titania or a mixed oxide thereof treated with a chlorinating agent; and (2) an organoaluminum compound. e

Description

SPECIFICATION A Process for Preparing an Olefin Polymer This invention relates to a process for preparing an olefin polymer using a Ziegler catalyst. More specifically, it relates to a process for polymerizing an olefin using a novel Ziegler catalyst. The catalyst has high activity, and the resulting olefin polymer has a high degree of tacticity (i.e., regularity in stereo-structure).

It is known that an olefin polymer can be produced using a catalyst composed of a titanium halogen compound and an organoaluminum compound. Recently, a catalyst composed of titanium halide, particularly, titanium tetrachloride supported on a variety of carriers, particularly, ground particles of magnesium halide was proposed in Japanese Patent Publication No. 1 2105/64 corresponding to U.S. Patent 3,238,146.

Japanese Patent Publication No.7583/71 suggests that a composite of a magnesium halide and a titanium halogen compound prepared by reducing titanium tetrachloride with a Grignard reagent has high catalytic activity, and that the magnesium halide in the composite also serves as a promoter that enhances the activity of the titanium halide.

Thus, various methods are known to synthesize a composite of a magnesium halide and a titanium halogen compound. The composite is an effective catalyst for polymerization of olefins and, particularly for propylene, when it is used as an admixture with an organoaluminum compound, but the resulting olefin polymer has a very low degree of isotacticity. For this reason, such a composite has practically no commercial value as a catalyst for the production of an olefin polymer.

Attempts have been made to produce an olefin polymer of improved isotacticity by using a modified catalyst composed of a titanium halogen compound, an organoaluminum compound, and a third catalyst component. Particularly effective third components are organic acid esters typified by ,-unsaturated carboxylic acid esters such as ethyl benzoate, ethyl p-toluylate and ethyl p-anisate, as described in Japanese Patent Publication Nos. 12140/71,21731/71 and 25706/72.

Research has also been conducted on the production of a catalyst combining the abovedescribed two prior art techniques, i.e., a catalyst composed of a magnesium halide, a titanium halogen compound, an organic compound as noted above as a third component, and an organoaluminum compound, as described in Japanese Patent Publication No. 46799/78. This catalyst is promising in that it has high activity, that the olefin polymer obtained may have a satisfactorily high degree of isotacticity, and that the step of decomposing and eliminating the spent catalyst after polymerization can be omitted entirely, resulting in reduced manufacturing cost. The fact is, however, that no technology has yet been provided that meets all these expectations.The greatest problem lies in the content of residual halogen atoms in the polymer obtained, which in the prior art has been undesirably high because, as is explained in detail below, of halogen atoms coming from magnesium halide used in the carrier.

The halogen atom in the titanium halogen compound conventionally used as a catalyst component has strong acidity, and the resulting olefin polymer has strong corrosive action on equipment used in the steps (e.g., granulation) after the polymerization. Therefore, it is generally suggested that the polymer should preferably contain the lowest possible concentration of halogen atoms. This consideration, coupled with the established idea that the titanium compound serves as an active center during polymerization, has led researchers to concentrate their efforts on decreasing the halogen atom content in the olefin polymer by increasing the yield of the polymer in terms of the amount of titanium halogen compound used.

However, the catalyst contains a greater amount of halogen atoms derived from the magnesium halide used as a carrier or promoter than halogen atoms derived from the titanium halogen compound.

This type of halogen atom is contained in the resulting olefin polymer in several tens to several hundred parts per million, and its effect on the polymer can by no means be neglected.

It is true that the halogen atom in the titanium halogen compound has strong acidity, but it is also true that an olefin polymer can be produced in several hundred thousand grams per gram of the titanium atom in the catalyst. This means the halogen atom content in the olefin polymer due to the titanium component is only about several parts per million, and the effect of freeing the polymer of such halogen atoms derived from the titanium component is not very critical. The magnesium halide, especially magnesium chloride, contained in the catalyst is well known as one of the strongest corrosives of iron, and the halogen atoms therefrom should also not be present in the olefin polymer produced.However, the greater part of the conventional catalyst is made up of magnesium halide, and the fact that the halogen atoms derived from the halide are contained in a far greater amount than the halogen atoms due to the titanium halogen compound has often been neglected in the prior art. It will therefore be understood that for producing an olefin polymer without the subsequent step of deashing, it is essential that the yield of the product in terms of the total halogen atom content, namely, the yield of the product in terms of the halide atoms from both the titanium halogen compound and the magnesium halide, be increased appreciably.

There have been several attempts in the prior art to improve the yield of the olefin polymer in terms of the halide from the magnesium halide, but they have not provided any remarkable result. For instance, Japanese Patent Application (OPI) (the term "OPI" as used herein refers to a "published unexamined Japanese Patent Application") Nos. 3113/72 and 3513/72, corresponding to British Patents 1,352,901 and 1,351,718, teach a method of adding silica, alumina, Na2CO3, CaSO4, etc., in the step of grinding a titanium compound. Japanese Patent Application (OPI) No. 148093/79 proposes a catalyst comprising a porous carrier such as silicon oxide or aluminum oxide impregnated with an electron donor having magnesium halide or titanium compound dissolved therein.These methods intend to reduce the halogen content in the catalyst by merely incorporating dissimilar carriers, but they only result in a decreased yield of the olefin polymer in terms of the titanium halogen compound, or a low degree of isotacticity, and no appreciable improvement is achieved. This is probably because the Ziegler catalyst comprising a titanium compound and aluminum compound are very sensitive to catalyst poisoning, and if oxygen-containing compounds as illustrated above are incorporated in the catalyst without making any provision against their potential poisoning effect, they will immediately attack the catalyst and reduce its activity.

To eliminate the problems with the conventional techniques, this invention achieves maximum reduction in the chlorine atom content remaining in the olefin polymer product by distributing uniformly a solid catalytically active component on the surface of a metal oxide carrier, and minimizes the occurrence of undesired side effects (i.e., a decrease in the polymer yield in terms of the titanium halogen compound, and a decrease in isotacticity of the polymer) by treating the carrier with a chlorinating agent before it is distributed on the carrier.

Therefore, this invention is characterized by a process for preparing an olefin polymer by a polymerization reaction wherein an olefin is contacted with a catalyst comprising: (1) a solid catalyst component composed of a magnesium halide, a titanium halogen compound, and an electron donor compound supported on a metal oxide carrier containing silica, alumina, magnesium, titania or a mixed oxide thereof, treated with a chlorinating agent; and (2) an organoaluminum compound.

The catalyst system used in this invention provides an olefin polymer in a higher yield in terms of the halogen atom in the catalyst, more specifically, in terms of the magnesium halide making up the greater part of the halogen component, than when the conventional catalyst is used, and the polymer obtained has a high degree of isotacticity. These advantages are presumably due to the effective use of the catalytically active component that is uniformly distributed over the metal oxide carrier. As a matter of fact, the catalyst of this invention can often provide a specific surface area of 400 m2/g or more.The conventional catalyst with magnesium halide exhibits the broad diffraction pattern of magnesium halide in an X-ray powder photography, whereas in the present invention the catalyst according to this invention, even if it contains several tens of percent of magnesium halide, is completely amorphous and does not exhibit a distinct X-ray diffraction pattern.

Another advantage of this invention is that it provides substantially spherical particles of olefin polymer and that the average particle size can be controlled freely. An industrially useful olefin polymer preferably comprises a minimal proportion of micro-fine particles smaller than 100 microns in diameter, but such a polymer cannot usually be obtained with a catalyst that contains ground particles of magnesium halide. However, this invention can provide a polymer entirely free from micro-fine particles 100 microns or less in diameter. What is more, the particle size of the polymer product can be controlled by properly controlling the particle size of the carrier used. In addition, the polymer comprises generally spherical particles, has good powder-like flowability, and has a very high bulk density.

1. Catalyst Component (I) The catalyst component (I) used in the method of this invention includes the transition metal component of a Ziegler catalyst, and it is composed of a magnesium halide, a titanium halogen compound and an electron donor compound supported on a metal oxide carrier.

(1) Subcomponents The component (I) is composed of the following subcomponents (A) through (D): (A) Metal Oxide Carrier The carrier basically consists of a metal oxide selected from the group consisting of silica, alumina, silica-alumina, magnesia and titania or a mixed oxide thereof, which may be used independently or as a mixture of such oxides. The carrier is desirably anhydrous, but it may contain a trace amount of incidental hydroxide. The catalyst may contain not more than about 10 wt% of an impurity, so long as the impurity does not significantly affect the properties of the catalyst, and such a catalyst is also included within the scope of the metal oxide carrier according to this invention.

Examples of permissible impurities are metal oxides such as sodium oxide, potassium oxide, calcium oxide, zinc oxide, nickel oxide and cobalt oxide, and carbonate, sulfate and nitrate salts such as sodium carbonate, potassium carbonate, magnesium carbonate, sodium sulfate, aluminum sulfate, titanium sulfate, aluminum nitrate and magnesium sulfate.

To achieve maximum prevention of catalyst poisoning, the carrier is desirably calcined at high temperatures and stored in an inert gas atmosphere. The carrier is preferably low in crystallinity so that it provides a broad diffraction pattern in an X-ray powder diffraction photograph. It is also preferred that the carrier have a large specific surface area. The carrier is subjected to subsequent steps in the form of a powder, and the particle size of the powder is desirably freely controllable, because it influences the particle size of the polymer produced. The pore volume and size of the carrier powder are not critical factors for the purposes of this invention, but large pore volume and size are generally preferred.

Treatment of the Metal Oxide Carrier with a Chlorinating Agent: The surface of the carrier described above is treated with a chlorinating agent before the subsequent steps, and this treatment is essential in this invention for preparing a catalyst that provides a high yield of polymer in terms of the amount of titanium halogen compound used and/or a high degree of tacticity of the polymer. Therefore, the term "chlorinating agent" as used herein means an agent that is capable of chlorinating at least the surface of the metal oxide carrier.

Illustrative suitable chlorinating agents include phosphorus pentachloride, phosphorus trichloride, phosphorus oxytrichloride, phosphorus dichloride, thionyl chloride, sulfuryl chloride, sulfur monochloride, sulfur dichloride, aluminum chloride, titanium tetrachloride, allyl chloride, acetyl chloride, ethanesulfonyl chloride, oxalyl chloride, phosgene, thiophosgene, toluene sulfonechloride, benzene sulfonechloride, benzoyl chloride, benzotrichloride, ethylene chlorohydrin, anhydrous hydrochloric acid and chlorine gas. Phosphorus pentachloride, phosphorus trichloride, phosphorus oxytrichloride, phosphorus dichloride, chlorine gas and benzotrichioride are preferred.

Various methods can be used to treat the metal oxide carrier with the chlorinating agent. For example, if the chlorinating agent is a liquid, it may be converted into a slurry, with which the carrier is treated. Alternatively, the high-temperature vapor of the liquid chlorinating agent may be used to treat the carrier. Yet another method is to force the chlorinating agent into contact with the carrier mechanically by grinding them together or other suitable means. Heating is not essential to the treatment with chlorinating agent, but it is generally effective for shortening the period of treatment. A specific temperature range for the treatment is from 0 to 4000C, preferably from 30 to 2000C, and more preferably from 50 to 1 500C.

The mechanism by which the chlorinating agent works has not been fully elucidated, but most probably residual hydroxyl groups on the surface of the oxide carrier (a catalyst poison) used in the polymerization of olefin react with the agent and are rendered harmless. This assumption is supported by the fact that analysis of the chlorinated carrier shows a chlorine content in the range of from 0.05 to 20 wt%, and typically from 0.5 to 1 8 wt%. The thus prepared metal oxide may be immediately used as a carrier for supporting a catalytically active component, but it may optionally be subjected to a treatment with magnesium halide which is described hereafter.

Treatment of the Metal Oxide Carrier With Magnesium Halide The surface of the metal oxide carrier treated with a chlorinating agent differs greatly from the surface of a carrier composed of magnesium halide, and if it is immediately used as a carrier for supporting a catalytically active component, a part of the resulting catalyst may be in a fine particulate form. To prevent this, part of the magnesium halide may initially be caused to be adhered to the metal oxide carrier as a support by using a polar organic compound. The supported magnesium halide serves as a binder that prevents the formation of micro-fine catalyst particles, and provides a particulate catalyst having an increased average particle size.

Examples of the magnesium halide that can be used as the binder include magnesium chloride, magnesium bromide, magnesium fluoride, magnesium monochloride and magnesium monobromide, and magnesium chloride is particularly preferred. The magnesium halide is used in an amount of generally from 1 to 50 wt%, preferably from 3 to 20 wt%, based on the amount of the carrier. The magnesium halide is usually adhered to the carrier support by treatment in the form of a solution in a polar organic compound, which is later removed. Illustrative polar organic compounds include the following: (a) Alcohols such as methyl alcohol, ethyl alcohol, butyl alcohol, hexyl alcohol, chloroethanol, ethylene glycol, phenol, o-cresol, p-cresol, and catechol.

(b) Esters such as methyl acetate, ethyl acetate, butyl acetate, phenyl acetate, and ethyl chloroacetate.

(c) Ketones such as acetone, methyl ethyl ketone, and chloroacetone.

(d) Aldehydes such as acetaldehyde and benzaldehyde.

(e) Ethers such as n-butyl ether, isoamyl ether, and tetrahydrofuran.

For preventing them from becoming a catalyst poison, these polar organic compounds are preferably used after dehydration and repiacing oxygen gas by an inert gas.

It is not essential that an electron donor compound be included in a solution of magnesium halide which is to be supported on the carrier, but such inclusion is an effective technique for improving the performance of the resulting catalyst. The electron donor compound may be used in an amount of from 1 to 100 wt%, and preferably from 10 to 40 wt%, based on the weight of the metal oxide carrier.

The polar organic compound is removed from the solution of magnesium halide by drying in an inert gas stream or vacuum drying. Heating is not essential, but if it is effected, the heating temperature is not more than 2000C. The dried carrier may be immediately subjected to the subsequent step, or, alternatively, it may first be treated with a Lewis acid to achieve complete removal of the polar organic compound. Illustrative Lewis acids include aluminum chloride, ethyl aluminum dichloride, antimony pentachloride, tin tetrachloride, titanium tetrachloride, boron trichloride, and boron trifluoride. These Lewis acids are generally used in the form of a solution in a non-polar solvent such as benzene, toluene, hexane, dichloroethane or chlorobenzene at room temperature or an elevated temperature not higher than 2000C.

(B) Magnesium Halide Illustrative magnesium halides useful in the invention include magnesium chloride, magnesium bromide, magnesium fluoride, magnesium monochloride and magnesium monobromide, and magnesium chloride is preferred. Part (30% or less on a molar basis, with respect to the magnesium) of the halogen in the magnesium halide may be replaced by a hydroxyl group, alkoxy group, acetate group or benzoate group, and such magnesium halide compounds are also included within the definition of magnesium halide according to this invention. Magnesium halides defined above may be used independently or as mixtures thereof.

(C) Titanium Halogen Compound Illustrative titanium halogen compounds include titanium tetrachloride, titanium tetrabromide, titanium trichloride, titanium trichlorobenzyl, titanium trichlorotrimethyl silylmethyl, and titanocene dichloride. Titanium tetrachloride is preferred for its high effectiveness and low price.

(D) Electron Donor Compound Illustrative electron donors are organic acid esters such as acetic esters (e.g., methyl acetate and ethyl acetate), a"B-unsaturated carboxylic esters, and lower alkyl ethers such as diethyl ether, isoamyl ether and tetrahydrofuran, and a,-unsaturated carboxylic acid esters. Monocarboxylic acid esters, and particularly monocarboxylic acid esters of monovalent alcohols are preferred. The "aj5-unsaturated" carboxylic acid esters include both ethylenically unsaturated and aromatic unsaturated carboxylic acid esters.

Examples of the a,-unsaturated monocarboxylic acid esters include esters of benzoic acid and lower alkyls having 1 to 12, and preferably 1 to 5 carbon atoms, such as methyl and ethyl, esters of p toluic acid and lower alkyls such as ethyl, esters of p-anisic acid and lower alkyls such as i-propyl, esters of methacrylic acid and lower alkyls such as methyl, esters of acrylic acid and lower alkyls such as ethyl, esters of cinnamic acid and lower alkyls such as methyl, and esters of maleic acid and di-lower alkyls such as dimethyl. Lower alkyl esters of benzoic acid or p-toluic acid are preferred.

(2) Preparation of the Solid Catalyst Component Various methods can be used to support the magnesium halide, titanium halogen compound and electron donor compound on the metal oxide carrier. Typical methods are as follows: Method (A) A magnesium halide is dissolved in a polar organic compound, and the solution is impregnated in a metal oxide carrier to obtain the halide supported on the carrier.

In this method, a metal oxide carrier is put into a solution of magnesium halide in a polar organic compound, and following thorough stirring, the solution is freed of the solvent by vacuum drying. The drying may be performed by heating. Vacuum drying may be replaced by addition of a poor or non solvent for the magnesium halide. Examples of such poor or non-solvents are hexane, heptane, benzene, silicon tetrachloride and dichloroethane. Another industrially practicable technique is to spray the carrier particles with a solution of magnesium halide.

A polar organic compound is preferably used as a solvent to form the solution of magnesium halide in a form from which it can be supported on the metal oxide carrier. Illustrative preferred polar organic compounds are those which are listed hereinabove. There is no particular limitation on the concentration of magnesium halide to be contained in these polar organic solvents, so long as it is held in solution, and the concentration is generally from about 1 to 30 wt%, and preferably from 3 to 20 wt%.

Generally, the proportion of the magnesium halide to the metal oxide carrier that is to support the halide is the same as that desired in the final catalyst system. However, magnesium halide is more likely to be lost in the course of catalyst preparation than the carrier, and so, in actual practice, the halide may be used in an amount slightly greater than what is required theoretically.

Polar organic compound remaining in the catalyst component in a slight amount will not have much adverse effect on the performance of the catalyst, but preferably its content is held to minimum.

The polar organic compound may be removed from the carrier by any of the methods of vacuum drying, heating and treatment with a Lewis acid which may be used independently or in combination. Vacuum drying and heating are simple and easy means for removing the greater part of the polar organic compound, but they are incapable of achieving its complete removal. Intense heating may restore the crystallinity of magnesium halide and impair its catalytic performance. Treatment with a Lewis acid is particularly effective in removing substantially any of the polar organic compound that cannot be totally eliminated by vacuum drying or heating.Illustrative Lewis acids include aluminum chloride, aluminum bromide, silicon tetrachloride, antimony pentachloride, antimony pentafluoride, boron trichloride, boron trifluoride, boron trifluoride ethyl etherate, tin tetrachloride, ethyl aluminum dichloride, titanium tetrachloride, titanium tetrabromide, phosphorus pentachloride, phosphorus pentabromide, and phosphorus oxychloride. These Lewis acids may be used per se or in the form of a solution. Treatment with Lewis acids may be accompanied by heating. There is also no particular limitation on the amount of Lewis acid to be used.

Next, the titanium halogen compound and an electron donor compound are deposited on the metal oxide carrier support. Treatments with the titanium halogen compound and electron donor compound may be consecutive or simultaneous. Alternatively, consecutive and simultaneous treatments may be combined together.More specifically, a titanium halogen compound (hereunder sometimes referred to as Ti), an electron donor compound (hereunder sometimes referred to as D) and a complex of the two (hereunder sometimes referred to as C) in a ratio of 1:1 or 1:2 can be added in various orders, and particularly effective orders are as follows: (a) D followed by Ti (b) D followed byTi+D (c) D followed by C (d) Ti followed by D (e) C (f) Ti+D An electron donor compound is advantageousiy supported on the carrier by stirring them together in a liquid form in the presence or absence of a solvent. Heating may be employed with advantage. Examples of the solvent are those generally known as inert solvents, such as hydrocarbons like hexane, heptane, benzene, toluene and methyl cyclohexane, and halogenated hydrocarbons like dichloroethane and chlorobenzene.The electron donor compound is used in a molar ratio of not more than 4.0/l, preferably not more than 2.0/i, with respect to the amount of magnesium halide contained in the carrier. When using consecutive treatments, the treated solid may or may not be washed before it is subjected to the subsequent treatment.

The titanium halogen compound can be supported in a manner substantially identical with the foregoing description of deposition on a support. If the compound is liquid, it may be blended with the carrier in the absence of a solvent. Only if an independent treatment with a titanium halogen compound is performed last, as in the case of (a) above, the treated solid must be washed thoroughly.

There is no particular limitation on the amount of the titanium halogen compound used.

If the carrier is treated with a complex of an electron donor compound and titanium halogen compound, a special inert solvent is necessary for dissolving the complex, which is generally a solid.

Illustrative suitable solvents are aromatic solvents such as benzene, toluene, and chlorobenzene, and chlorinated hydrocarbons such as dichloromethane, dichloroethane, chloroform, chlorobenzene and dichlorobenzene. The carrier treated with the complex need not be washed subsequently. Again, heating may be employed with advantage. The concentration of the complex in solution is generally in the range of from 0.05 to 100 millimols/liter, preferably from 0.5 to 10 millimols/liter at a temperature between OOC and the boiling point of the solvent.

The polar organic compound may be the same as the electron donor, and in such a case, by using a polar organic solvent for making a solution of magnesium halide, the subsequent treatment with an electron donor may be omitted. Magnesium halide, titanium halogen compound and electron donor may be supported on the metal oxide carrier by adding the titanium halogen compound and optionally the electron donor to a solution of the magnesium halide in a polar organic compound which is yet to be brought into contact with the metal oxide.

Method (B) A complex of magnesium halide and electron donor compound is dissolved in a liquid titanium halogen compound, and the solution is impregnated onto the metal oxide carrier to have the three compounds supported on it.

This method is based on the finding that although magnesium halide does not dissolve at all in a titanium halogen compound, especially titanium tetrachloride, MgX2. nD, a complex of magnesium halide and an electron donor D (e.g., ethyl benzoate) does dissolve easily in the titanium halogen compound at elevated temperature when n is about 0.2 or more. The resulting solution comprises an integral mixture of a titanium component, magnesium compound and the electron donor, wherein magnesium halide does not function as a carrier. By bringing the mixture into direct contact with the surface of a carrier from which any potential catalyst poison has been removed, a very useful catalyst component is provided.

In cases where (1) n of the above formula is in the range of from 0.2 to 0.3, or (2) the amount of the above complex is held at a large level with respect to the amount of the solvent (i.e., TiCI4), it may appear initially that the perfect dissolution of the complex is not achieved. However, there exists a dynamic equilibrium in dissolution and precipitation of part of the above complex resulting eventually an effective supporting of the whole complex over the carrier.

This is substantiated by the fact that the particle size distribution of the supported catalyst (and hence that of the polymer produced) is quite similar to that of the catalyst which is produced through the perfect dissolution, giving very small percentages of micro-fine catalyst particulate.

The method (B) is hereunder described in detail.

Synthesis of MgX2- nD The complex MgX2. nD (wherein n is 0.2 to 2.0, preferably from 0.25 to 0.5) is synthesized by bringing magnesium halide into contact with an electron donor compound. More specifically, a slurry of fine particles of magnesium halide and an electron donor compound may be stirred with heating in the presence or absence of a nonpolar solvent. Alternatively, fine particles of magnesium halide may be reacted with the high-temperature vapor of an electron donor compound. According to another advantageous method, the magnesium halide and electron donor compound may be ground together in a vibrating mill or other suitable grinding means such as a ball mill and impact mill. To achieve thorough reaction between the magnesium halide and electron donor compound, a grinding aid may be used with advantage.Examples of the grinding aid are titanium tetrachloride, silicon tetrachloride and polysiloxane. Such aid may be added either at the start or during the course of the grinding.

Dissolution of MgX2. nD The thus prepared complex of MgX2 and electron donor is then dissolved in a solvent which may be replaced by the titanium halogen compound that is one of the sub-components of the catalyst component (I) of the catalyst to be used in this invention. But it is possible to dilute the compound with a certain amount of a non-polar solvent. Preferred examples of the non-polar solvent are halogenated hydrocarbons such as dichloroethane, dichloropropane, dichlorobutane, propyl chloride, chlorobenzene, dichlorobenzene, trichlorobenzene, propyl bromide and ethyl iodide. Such non-polar solvent may be used in an amount up to twice the volume of the titanium halogen compound. Aromatic hydrocarbons such as benzene and toluene may be used as a diluent in an amount smaller than that of the halogenated hydrocarbon solvent.Hydrocarbons such as hexane, heptane and cyclohexane may also be used in only a small amount.

The dissolution of the complex is promoted by heating at a temperature in the range of from 0 to 2500 C, preferably from 30 to 2000 C, and more preferably from 60 to 1 500C. The dissolution is further promoted by stirring.

As mentioned before, magnesium halide does not dissolve at all in a titanium halogen compound, especially titanium tetrachloride, but MgX2. nD, a complex of magnesium halide and an electron donor compound (e.g., ethyl benzoate) dissolves easily in the titanium halogen compound when n is about 0.2 or more, and preferably about 0.25 or more at elevated temperature. The resulting "solution" is very viscous, and it is difficult to determine scientifically whether such viscous substance is a true solution or a colloidal dispersion of the complex MgX2. nD. In any event, the "solution" of the complex can be brought into contact with the metal oxide to realize very effective distribution over its surface.

Therefore, before dissolving in a liquid titanium halogen compound, magnesium halide is contacted by an organic electron donor in a molar ratio of at least 0.2, preferably from 0.25 to 2.0, more preferably from 0.3 to 0.5. These molar ratios guarantee the dissolution of the complex in the liquid titanium halogen compound.

Binding the Active Components to the Chlorinated Metal Oxide Carrier The catalytically active components can be easily bound to the chlorinated metal oxide carrier by simply adding the metal oxide to the solution prepared above with stirring. If n of MgX2. nD is from 0.2 to 0.3 and the complex dissolves only partially, it is essential that the metal oxide be present together with magnesium halide and electron donor when they are dissolved in the titanium halogen compound.

It is perfectly all right if the same procedure is followed when n is from 0.2 to 2.0. Heating is effective in accelerating the binding of the catalytically active components to the metal oxide. Cooling the heated solution before separation of the solid is not essential but effective. This is presumably because cooling helps complete the binding of the surface of the oxide to the catalytically active components which are held in solution during heating and hence are left unsupported.

The nature of the bond between the supported components and the surface of the metal oxide has not been characterized satisfactorily, but most probably, it is an appreciably strong bond formed through the intermediary of the chlorine on the surface of the chlorinated metal oxide and the halogen of the titanium or magnesium halogen compound. This is apparent because the bound catalytic components will not separate from the metal oxide even if they are mixed with hexane or other solvent to form a slurry, and the particle size of the olefin polymer product has a very close correlation with the particle size of the metal oxide powder.

After the binding treatment above, the solid catalyst is separated from the solution and washed for subsequent use in polymerization of olefins.

(3) Proportions of Sub-components The solid catalyst component (I) thus prepared is composed of the sub-components (A) through (D) in the following proportions on the basis of the amount of the final catalyst.

(a) Metal oxide 30 to 95 wt%, and preferably 35 to 90 wt% (b) Magnesium halide 5 to 50 wt%, and preferably 10 to 40 wt% (c) Electron donor compound 0.1 to 20 wt%, and preferably 0.2 to 15 wt% (d) Titanium halogen compound 2 to 30 wt%, and preferably 4 to 20 wt% 2. Catalyst Component (II) The catalyst component (II) of the catalyst to be used in the method of this invention is an organoaluminum compound of the formula: AíRnX3~n, wherein R is hydrogen, or a hydrocarbon group having 1 to 20 carbon atoms, and particularly where R is an alkyl group, an aralkyl group or an aryl group; X is a halogen, particularly chlorine or bromine; and n is an integer from 0 to 3.Specific examples are (a) trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trioctyl aluminum and tridecyl aluminum; (b) diethyl aluminum monochloride, diisobutyl aluminum monochloride, ethyl aluminum sesquichloride, and ethyl aluminum dichloride; (c) diisobutyl aluminum hydride. The organoaluminum compound is used in a weight ratio of 0.01 to 200, preferably from 0.03 to 100, with respect to the amount of the catalyst component (I). The exact ratio is determined by the content of a catalyst component (III) to be described hereunder.

3. Catalyst Component (III) The electron donor compound defined in 1., (1), (D) may again be used as the catalyst component (III). It may be the same or a different compound from the type of electron donor compound used in the preparation of the solid catalyst component. The catalyst component (III) is used in a molar ratio of from 0 to 0.5, preferably from 0 to 0.4, based on the amount of the organoaluminum compound.

4. Polymerization of Olefins (1) Olefins The olefins to be polymerized in the presence of the catalyst system described hereinabove are a olefines of the formula: R-CH=CH2 (wherein R is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms and which may have a substituent). Specific examples of such olefins are ethylene, propylene, butene-1, pentene-1, and 4-methylpentene-1. Ethylene and propylene are preferred. A mixture of a-olefins may also be used; for instance, propylene may be copolymerized with another aolefin used in an amount of up to 20 wt% based on the amount of the propylene. Alternatively, ethylene may be copolymerized with 1 to 30 wt% of propylene or butene-1. Other copolymerizable aolefin monomers such as vinyl acetate and diolefin may also be used.

(2) Polymerization The catalyst system described hereinabove can be used not only in ordinary slurry polymerization, but also in liquid phase solventless polymerization or gas phase polymerization performed in the substantial absence of a solvent. Especially the narrow particle size distribution of the catalyst in this invention makes it an ideal means for the gas phase floating bed polymerization. It is applicable to either continuous or batchwise polymerization as well as to polymerization involving prepolymerization step. Solvents suitable for use in slurry polymerization include saturated aliphatic or aromatic hydrocarbons such as hexane, heptane, cyclohexane and toluene which may be used alone or as a mixture.The polymerization temperature is generally in the range of from room temperature to about 2000C, preferably from 50 to 1 500 C. Hydrogen may be used as a molecular weight modifier.

The method of this invention is now described in greater detail by reference to the following examples and comparative examples which are given here for illustrative purposes only and are by no means intended to limit the scope of the invention.

Example 1 In this example, all procedures were followed in an inert gas atmosphere.

Preparation of Silica Carrier Silica gel (No. 951 manufactured by Fuji Davison Chemical Ltd.) was dried by calcination at 5000C for 5 hours. A 500-ml four-necked flask was charged with 1 8 g of the silica, 1 8 g of phosphorus pentachloride and 200 ml of dehydrated 1,2-dichloroethane, and the mixture was heated under reflux for 5 hours with stirring. It was then washed with 12-dichloroethane thoroughly and dried. The carrier contained 8.7 wt% chlorine.

Preparation of Solid Catalyst Component A mixture of 0.2 mol of anhydrous magnesium chloride and 0.08 mol of ethyl benzoate was charged into a vibrating mill pot having an internal volume of 1 liter and ground for 24 hours to produce MgCl2. 0.4 EB (EB representing ethyl benzoate). The pot was further charged with 0.08 mol of titanium tetrachloride and grinding was continued for an additional 24 hours. The thus produced ground solid particles (1.62 g) were charged into a 500-ml four-necked flask which was further charged with 100 ml of titanium tetrachloride and 10 ml of 1,2-dichloroethane, and the contents were heated at 800C for 2 hours under stirring to form a solution. To the solution, 4 g of the silica carrier prepared above was added.The heating was discontinued but the stirring was continued until the temperature of the mixture returned to room temperature. The solid content was then separated from the solution and washed thoroughly with dichloroethane and n-hexane.

Analysis of the resulting solid catalyst component revealed that it contained 1.21 % titanium, 3.27% magnesium, 14.5% chlorine, 1.9% ethyl benzoate and the remainder (79,1%) silica. The component had a specific surface area of 459 m2/g.

Polymerization of Propylene A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component prepared above, 50 mg of triethyl aluminum and 1 8 mg of ethyl p-toluate was charged into an autoclave having an internal volume of 1 liter. The autoclave was also charged with 700 ml of liquefied propylene which was polymerized at 700Cfor 1 hour to provide a polypropylene powder in 305 g. The yields of the polymer in terms of various criteria were as follows: 610 kg per gram of Ti atom, 57.6 kg per gram of MgCI2, and 50.9 kg per gram of chlorine atom. The isotactic index (II) of the polymer was 92.0%. The polymer yield in terms of titanium atom was great, but what was most characteristic of the catalyst was the greatness of the yield in terms of MgCI2 and chlorine atom.The theoretical residual chlorine content in the polymer was equivalent to 20 ppm.

Comparative Example 1 A solid catalyst component identical with that was prepared in Example 1 was prepared except using no silica carrier. When heated to 800 C, the solid component dissolved completely to form a clear, pale green solution. When 100 ml of n-hexane was added to the solution gradually, the solid was precipitated. Such solid catalyst component was washed thoroughly and dried. Analysis showed that said component contained 1.2% titanium, 18.77% magnesium and 60.6% chlorine. A catalyst system composed of 0.4 mg (in terms of titanium atom) of the solid catalyst component, 40 mg of triethyl aluminum and 14 mg of ethyl p-toluate was used in polymerization of propylene under the same conditions as used in Example 1. Polypropylene was produced in an amount of 202 g.The yields of the polymer in terms of various criteria were as follows: 505 kg per gram of titanium atom, 12.5 kg per gram of MgCI2 and 1 5.2 kg per gram of chlorine atom. The isotactic index (Il) of the polymer was 92.8%.

Comparison with the data of Example 1 shows that the yield of the polymer obtained using the catalyst of Comparative Example 1 was not much different as far as it was in terms of titanium atom but that the yield in terms of MgCI2 and hence chlorine atom was much lower than that achieved in Example 1. The theoretical residual chlorine content in the polymer was equivalent to 66 ppm which was more than three times the chlorine content in the polymer prepared in Example 1.

Example 2 Both anhydrous magnesium chloride (0.2 mol) and ethyl benzoate (0.08 mol) were grounded together for 48 hours to form a complex of the two compounds. No titanium tetrachloride was added during the grinding operation. A solid catalyst component was prepared from a mixture of 1.1 g of the complex prepared above and 0.67 g of the silica carrier prepared in Example 1, and the conditions for preparation were the same as in Example 1. The resulting catalyst component contained 1.45% of titanium. A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst cOmponent 50 mg of triethyl aluminum and 1 5 mg of ethyl p-toluate was used in polymerization of propylene under the same conditions as used in Example 1. Polypropylene was produced in an amount of 199 g. The yield of the polymer was 398 kg per gram of titanium atom. The isotactic index (II) of the polymer was 93.4%.

Comparative Example 2 A solid catalyst component identical with that was prepared in Example 2 was prepared except that the silica carrier obtained by merely calcining the silica gel No. 951 as used in Example 1 at 5000C for 5 hours was used. The solid catalyst component produced contained 4.38% of titanium. A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component, 125 mg of triethyl aluminum and 55 mg of ethyl p-toluate was used in polymerization of propylene under the same conditions as used in Example 2. Polypropylene was produced in an amount of 65 g. The yield of the polymer was 130 kg per gram of titanium atom, and the isotactic index (II) of the polymer was 93.5%.From the comparison with the data of Example 2, one can see how greatly the chlorination of the silica carrier contributed to improvement in the polymer yield.

Example 3 A solid catalyst component identical with that was obtained in Example 2 was prepared except that the amount of the silica carrier was increased to 4 g. The catalyst component contained 1.28% titanium, 3.47% magnesium and 16.1% chlorine. A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component, 50 mg of triethyl aluminum and 14 mg of ethyl ptoluate was used in polymerization of propylene under the same conditions as in Example 2.

Polypropylene was produced in an amount of 186 g. The yields of the polymer in terms of various criteria were as follows: 372 kg per gram of titanium atom, 35.2 kg per gram of MgCI2 and 29.6 kg per gram of chlorine atom. The isotactic index (II) of the polymer was 93.5%. The theoretical content of the residual chlorine in the polymer was equivalent to 34 ppm.

Example 4 Under the same conditions as in Example 1, both 0.2 mol of magnesium chloride and 0.06 mol of ethyl benzoate were ground together for 24 hours, and thereafter, 0.06 mol of titanium tetrachloride was added to the mixture which was subjected to grinding for another 24 hours. A solid catalyst component was prepared from a mixture of 8.3 g of the ground solid particles obtained above and 4 g of the silica carrier prepared in Example 1, and the conditions for preparation were the same as in Example 1. The resulting catalyst component contained 3.19% titanium, 9.94% magnesium, 36.5% chlorine, 10.3% ethyl benzoate, and the remainder (40.1%) silica.A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component, 50 mg of triethyl aluminum and 15 mg of ethyl p-toluate was used in polymerization of propylene under the same conditions as in Example 1.

Polypropylene was produced in an amount of 228 g. The isotactic index (II) of the polymer was 94.3%, and its bulk density was 0.39 g/ml. The yields of the polymer in terms of various criteria were as follows: 456 kg per gram of titanium atom, 37.3 kg per gram of MgCl2, 39.9 kg per gram of chlorine atom, and 14.5 kg per gram of the solid catalyst component. The theoretical residual chlorine content in the polymer was equivalent to 25 ppm.

Example 5 Under the same conditions as in Example 1, both 0.2 mol of magnesium chloride and 0.04 mol of ethyl benzoate were ground together for 24 hours and, thereafter, 0.04 mol of titanium tetrachloride was added to the mixture which was subjected to grinding for another 24 hours. A solid catalyst component was prepared from a mixture of 6.8 g of the ground solid particles obtained above and 4 g of the silica carrier prepared in Example 1, and the conditions for preparation were the same as in Example 1. The resulting catalyst component contained 2.30% titanium, 10.5% magnesium and 38.6% chlorine. A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component, 50 mg of triethyl aluminum and 22 mg of ethyl p-toluate was used in polymerization of propylene under the same conditions as in Example 1.Polypropylene was produced in an amount of 317 g. The isotactic index (II) of the polymer was 94.3% and its bulk density was 0.40 g/ml. The yields of the polymer in terms of various criteria were as follows: 634 kg per gram of titanium atom, 35.5 kg per gram of MgCl2, 37.8 kg per gram of chlorine atom, and 14.6 kg per gram of the solid catalyst component. The theoretical content of the residual chlorine in the polymer was equivalent to 26 ppm.

Example 6 A mixture of 18 g of silica gel (No. 951 manufactured by Fuji Davison Chemical Ltd.) calcined at 5000C and 100 ml of benzotrichloride was charged in a four-necked flask and heated at 1 300C for 25 hours under stirring. The solid content was separated from the solution and washed thoroughly with dichloroethane and n-hexane, and dried to obtain a silica carrier.

A solid catalyst component identical with that was prepared in Example 5 was prepared except that the silica carrier was replaced by 4 g of the silica carrier obtained above. The resulting solid catalyst component contained 2.22% titanium, 9.68% magnesium, 33.6% chlorine, 6.8% ethyl benzoate and the remainder (47.7%) silica. A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component, 200 mg of triethyl aluminum and 85 mg of ethyl p-toluate was used in polymerization of propylene under the same conditions as used in Example 1. Propylene was produced in an amount of 215 g.The isotactic index (II) of the polymer was 95.1% and its bulk density was 0.38 g/ml. the yields of the polymer in terms of various criteria were as follows: 430 kg per gram of titanium atom, 25.2 kg per gram of MgCl2, 28.4 kg per gram of chlorine atom, and 9.5 kg per gram of the solid catalyst component. The theoretical residual chlorine content of the polymer was equivalent to 36 ppm.

Example 7 A mixture of 3 g of the silica carrier prepared in Example 1, 0.7 g of anhydrous magnesium chloride, 1.6 ml of ethyl benzoate and 1 5 ml of dehydrated ethyl acetate was charged in a 500-ml fournecked flask, and the contents were stirred at 600C for 30 minutes to make a solution of magnesium chloride. The solution was then stripped of the solvent by evaporation in an argon stream. A carrier was prepared from the solid which was heated to 1 000C to achieve complete drying.

Preparation of Solid Catalyst Component A mixture of 0.2 mol of anhydrous magnesium chloride and 0.04 mol of ethyl benzoate was charged into a vibrating mill pot having an internal volume of 1 liter and ground for 24 hours to produce MgCI2 0.2 EB (EB representing ethyl benzoate). The pot was further charged with 0.04 mol of titanium tetrachloride and grinding was continued for an additional 24 hours. The thus produced ground solid particles (3.9 g) were combined with the carrier prepared above and 100 ml of titanium tetrachloride, and the mixture was heated at 800C for 2 hours under stirring to form a solution. The heating was discontinued but the stirring was continued until the temperature of the mixture returned to room temperature. The solid content was then separated from the solution and washed thoroughly with dichloroethane and n-hexane.

Analysis of the resulting solid catalyst component showed that it contained 1.43 wt% titanium, 8.76 wt% magnesium, 30.1 wt% chlorine, 3.3 wP/O ethyl benzoate and 56.4 wt% silica.

Polymerization of Propylene The procedure of Example 1 was repeated to polymerize 700 ml of liquefied propylene using a catalyst system comprising 0.4 mg (in terms of titanium atom) of the solid catalyst component prepared above, 50 mg of triethyl aluminum and 1 8 mg of ethyl p-toluate. The monomer pressure dropped in 50 minutes, whereupon the polymerization was stopped. As a result, 308 g of powdered polypropylene was produced, and it had a bulk density of 0.41 g/ml. The polymer yields per gram of titanium atom, MgCI2 and chlorine atom were 770 kg, 32.1 kg and 36.6 kg, respectively. The isotactic index (II) of the polymer was 93.8%. The theoretical content of the residual chlorine in the polymer was equivalent to 27 ppm.

A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component prepared above, 510 mg of triethyl aluminum and 242 mg of ethyl p-toluate was used in suspension polymerization of propylene that was performed in the following manner: both 500 ml of dehydrated industrial heptane and the catalyst were charged into a 1-liter autoclave, and propylene was subjected to prepolymerization at a pressure of 1 kg/cm2G at room temperature for 1 5 minutes.

Thereafter, 250 ml of hydrogen was added to the reaction mixture, and the temperature was increased to 650C at which polymerization was performed at a propylene pressure of 9 kg/cm2G for 1.5 hours. As a result, 91.0 g of powdered polypropylene and 1.25 g of solvent-soluble polymer were produced. The powder polymer had a bulk density of 0.38 g/ml, a melt index (MI) of 3.2, and an isotactic index (II) of 96.2%. The grain size distribution of the powder polypropylene is shown in Table 1 below, from which it is clear that the polymer has a good particle size distribution wherein the amount of micro-fine particles is very small.

Table 1 Sieving Analysis Polymer Particle Size wt % 53 y or less 1.0 74 zz or less 1.1 105 iu or less 1.3 149,uorless 3.8 297 y or less 15.2 500 y or less 52.6 840 y or less 89.8 840Mormorn 100 100 Example 8 A powdered alumina manufactured by Catalysis Society of Japan (JRC-ALO-2, average mean size 60 y) was calcined at 5000C for 5 hours, and chlorinated in the same manner as in Example 1. The resulting alumina contained 14.4 wt% chlorine. Using the alumina as a carrier, a solid catalyst component was prepared in a manner identical to that of Example 7. The resulting solid catalyst component contained 1.47 wt% titanium and 8.65 wt% magnesium. A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component, 477 mg of triethyl aluminum and 226 mg of ethyl p-toluate was used in suspension polymerization of propylene following the procedure of Example 7 except that 100 ml of hydrogen was supplied. As a result, 74.5 g of powdered polypropylene (bulk density 0.38, Ml 2.0, II 95.6%) and 1.68 g of a solvent-soluble polymer were produced. The polypropylene powder contained 9.9 wt% of fine particles 105 u or less in diameter.

Example 9 A heavy magnesium oxide (grade 1, manufactured by Wako Pure Chemical Industries, Ltd.) was chlorinated in the same manner as in Example 1). The resulting magnesia contained 26.5% chlorine.

Using the magnesia as a carrier, a solid catalyst component was prepared in a manner identical to that of Example 7. The resulting solid catalyst component contained 1.73% titanium and 44.4% chlorine. A catalyst system having the same composition as that of Example 8 was used in suspension polymerization of propylene under the same conditions as in Example 8. As a result, 66.0 g of a powdered polypropylene (bulk density 0.38, Ml 12.8, 11 94.9%) and 1.67 g of a solvent-soluble polymer were produced. The polypropylene powder contained 7.6 wt% of fine particles 105 u or less in diameter.

Examples lotto 12 Magnesium chloride dissolved in 1 5 ml of ethyl acetate in the amounts indicated in Table 2 was applied to 3 g of the silica carrier prepared in Example 1.

The solvent was evaporated in an argon stream to provide a silica carrier supporting magnesium chloride. The silica carrier was then mixed with aluminum chloride (the amount being indicated in Table 2) and 100 ml of dichloroethane and heated under reflux for 2 hours. The solid mixture was washed, and further mixed with ground particles of MgCl2. 0.4 EB 0.4 TiCI4 (the amount being indicated in Table 2) and 100 ml of titanium tetrachloride, and heated at 80"C for 2 hours under stirring to provide a silica carrier supporting the catalytically active components. The silica carrier was then washed to provide a solid catalyst component.A catalyst system comprising 0.5 mg (in terms of titanium atom) of the component, 50 mg of triethyl aluminum and 18 mg of ethyl p-toluate was used in polymerization of liquefied propylene to form a powdered polypropylene whose properties are specified in Table 2. In each of Examples 10 to 12, the polypropylene powder contained 1 wt% or less of fine particles 105 y or less in diameter.

Table 2 Example Example Example 10 11 12 MgCl2 on silica (g) 0.3 0.7 1.5 AIR13 (g) - 0.3 0.6 Ground solid particles (g) 1.6 1.6 3.4 Ti in catalyst (wt %) 1.32 1.49 1.75 Mg in catalyst (wt %) 5.72 7.35 10.87 Cl in catalyst (wt %) 21.6 27.8 36.1 Polymer yield (kg/g-Ti) 472 568 532 Isotactic index (%) 93.2 90.1 91.9 Bulk density (cc/g) 0.36 0.37 0.37 Example 13 A solid catalyst component containing 1.78 wt% titanium and 31.2 wt% chlorine was prepared by repeating the procedure of Example 5 except that the silica carrier was replaced by magnesium silicate (grade 1, manufactured by Wako Pure Chemical Industries, Ltd., specific surface area 1 6.2 m2/g) which was calcined and treated with phosphorus pentachloride.The resulting solid catalyst component contained 1.78% titanium and 31.2% chlorine. A catalyst system composed of 0.5 mg (in terms of titanium atom) of the solid catalyst component, 1 79 mg of triethyl aluminum and 85 mg of ethyl p-toluate was used in suspension polymerization of propylene following the procedure of Example 7 except that 500 ml of purified hexane and 1 50 ml of hydrogen were supplied. As a result, 1 83 g of polypropylene having an isotactic index of 92.4%, a melt index of 0.4 and a bulk density of 0.36 was obtained. The yields of polymer per gram of titanium atom and chlorine atom were 366 kg and 20.9 kg, respectively. The theoretical content of the residual chlorine in the polymer was equivalent to 48 ppm.

Example 14 Preparation of Solid Catalyst Component 3 g of the silica carrier prepared in Example 1 was mixed with 20 ml of dehydrated ethyl acetate containing 1 g of anhydrous magnesium chloride, and the mixture was slowly dried under vacuum to provide a silica carrier supporting magnesium chloride. The carrier was dried and further heated to 1 300C while the residual solvent was removed under vacuum. The solid product was mixed with 0.4 g of anhydrous aluminum chloride and 100 ml of dichloroethane, and the mixture was heated under reflux for 2 hours with stirring. The mixture was then let stand. The solid content was separated from the solution and washed with dichloroethane. The solid was mixed with 0.6 ml of ethyl benzoate and 50 ml of dichloroethane, and the mixture was heated under reflux for 2 hours with stirring. The mixture was then let stand.The solid content was separated from the solution and mixed with 25 ml of titanium tetrachloride and 75 ml of dichloroethane. The mixture was heated under reflux for 2 hours with stirring. After standing, the solid content was separated from the solution and washed with dichloroethane. The so prepared solid catalyst component (I) contained 0.86 wt% titanium, 6.6 wt% magnesium, 1.3 wt% ethyl benzoate and 18.9 wt% chlorine.

Polymerization Into an autoclave having an internal volume of 1 liter, 0.5 mg (in terms of titanium atom) of the solid catalyst component was charged in a propylene stream. The autoclave was also charged with 75 mg of triethyl aluminum, 32.4 mg of ethyl p-toluate and 700 ml of liquefied propylene, and polymerization was performed for 1 hour. As a result, 270 g of a white powder of polypropylene was produced. The polymer had an isotactic index of 93.3% and a bulk density of 0.38. The yields of polymer per gram of titanium atom and MgCI2 were 540 kg and 17.9 kg, respectively. The total residual chlorine content in the polymer was equivalent to 41 ppm. The polypropylene powder comprised particles of uniform size and contained few micro-fine particles. Also, it was highly flowable as a powder.

Example 15 The procedure of Example 14 was repeated to support magnesium chloride except that the weight ratio of magnesium chloride to silica was 1:4. The solid product was dried under vacuum, and 4 g of it was mixed with 50 ml of titanium tetrachloride, and the mixture was heated at 1 3QOC for 2 hours under stirring. The mixture was then cooled and let stand. The solid content was separated from the solution and washed with dichloroethane. The solid product was then mixed with 100 ml of dichloroethane containing 1.25 ml of ethyl benzoate, and the mixture was heated under reflux for 2 hours with stirring. The mixture was then let stand, and the solid content was separated from the solution. The separated solid matter was mixed with 100 ml of dichloroethane containing 10 ml of titanium tetrachloride.The mixture was heated under reflux for an additional 2 hours with stirring. The mixture was then cooled and let stand. The solid content was separated from the solution and washed with dichloroethane to provide a solid catalyst component. The resulting solid catalyst component contained 2.05 wt% titanium, 2.3 wt% magnesium, 1.8 wt% ethyl benzoate and 12.9 wt% chlorine.

Polymerization The procedure of Example 1 was repeated to polymerize 700 ml of liquefied propylene using a catalyst system comprising 1 mg (in terms of titanium atom) of the solid catalyst component, 80 mg of triethyl aluminum and 27.3 mg of ethyl p-toluate. As a result, 135 g of a highly flowable powder of polypropylene was produced. The polymer had a bulk density of 0.37 and an isotactic index of 91.6%.

The polymer yield per gram of titanium atom was 135 kg. The yield per gram of MgCl2 was also as high as 30.6 kg. The theoretical total content of the residual chlorine in the polymer was equivalent to 47 ppm.

Example 16 A solid catalyst component was prepared by following the procedure of Example 1 5 modified in the following points.

(1) A solution of magnesium chloride in ethyl acetate was added to silica, and instead of vacuumdrying, the resulting slurry was mixed with 100 ml of n-hexane under stirring to cause precipitation of magnesium chloride on the silica. The silica was then washed and dried under vacuum.

(2) Ethyl benzoate was used in an amount of 1.0 ml.

The resulting solid catalyst component contained 1.6 wt% titanium, 4.8 wt% magnesium, 2.0 wt% ethyl benzoate, and 1 6.4 wt% chlorine. The component had a BET surface area of 411 m2/g. A catalyst system comprising 1.0 mg (in terms of titanium atom) of the solid catalyst component, 80 mg of triethyl aluminum and 27.3 mg of ethyl p-toluate was used in polymerization of 700 ml of liquefied propylene following the procedure of Example 14. As a result, 1 87 g of a highly flowable powder of polypropylene was produced.

The polypropylene powder had a bulk density of 0.42 and an isotactic index of 90.7%. The yields of polymer per gram of titanium atom and MgCI2 were 187 kg and 16.4 kg, respectively. The polypropylene had a particle size distribution data set forth below.

Individual Cumulative Weight Weight Particle Size Percents Percents 74orless 0 on less 0.05 0.05 74 to 104 u 0.20 0.25 104 to 147 0.03 0.28 147 to 295 y 1.94 2.22 295 to 495 27.32 29.54 495 to 589 u 20.93 50.47 589 to 833 u 47.86 98.33 833 to 1,168 y 1.52 99.85 1,168 to 1,397 y 0.03 99.88 1,397 to 1,651,u 0.04 99.92 1,651 yormore 0.08 100.00 As is shown above, the polypropylene comprised of uniform size particles and it was substantially free of micro-fine particles of about 100,u or less that are involved in the conventional production of polypropylene.

Comparative Example 3 A solid catalyst component was prepared in the same manner as in Example 15 except that no chlorination treatment with phosphorus pentachloride was conducted. The resulting solid catalyst component contained 6.64 wt% titanium, 4.0 wt% magnesium and 1.0 wt% ethyl benzoate. A catalyst system comprising 1 mg (in terms of titanium arom) of the solid catalyst component, 80 mg of triethyl aluminum and 25 mg of ethyl p-toluate was used in polymerization of 700 ml of liquefied propylene following the procedure of Example 1. As a result, 48 g of powdered polypropylene was obtained. The polymer had a bulk density of 0.33 and its isotactic index was as low as 89.7%. The yield of the polymer per gram of titanium atom was also as low as 48 kg.

Example 17 A solid catalyst component was prepared by following the procedure of Example 1 6 modified in the following points.

(1) Ethyl acetate used as solvent was replaced by acetone.

(2) Ethyl benzoate was used in an amount of 1.2 ml.

The resulting solid catalyst component contained 4.53 wt% titanium, 6.20 wt% magnesium, 0.67 wt% ethyl benzoate and 21.4 wt% chlorine. A catalyst system comprising 0.5 mg (in terms of titanium atom) of the solid component, 120 mg of triethyl aluminum and 55 mg of ethyl p-toiuate was used in polymerization of propylene following the procedure of Example 1. As a result, 1 20 g of a powdered polypropylene was obtained. The polypropylene had a bulk density of 0.41 and an isotactic index of 93.5%. The yields of the polymer per gram of titanium atom and MgCI2 were 240 kg and 45 kg, respectively. The polymer had a particle size distribution data set forth below.

Individual Cumulative Weight Weight Particle Size Percents Percents 74 4 or less 0.5 0.5 74 to 104 y 0.8 1.3 104to147,u 9.2 10.5 147 to 295 y 77.0 87.5 295 to 495,u 12.0 99.5 495 to 833,u u 0.5 100.0 Example 18 A solid catalyst component was prepared in the same manner as in Example 1 5 except that phosphorus pentachloride was replaced by an equal amount of phosphorus oxytrichloride. The resulting solid catalyst component contained 6.41 wt% titanium, 2.46 wt% magnesium, 0.62 wt% ethyl benzoate, and 14.7 wt% chlorine. The atomic ratio of Ti to Mg was 1:1.3.A catalyst system comprising 1 mg (in terms of titanium atom) of the solid catalyst component, 1 80 mg of triethyl aluminum and 78 mg of ethyl p-toluate was used in polymerization of propylene following the procedure of Example 1. As a result, 37.5 g of a powdered polypropylene was produced. The yields of the polymer per gram of titanium atom and MgCI2 were 37.5 kg and 24.9 kg, respectively. The polymer had an isotactic index of 94.3%.

Example 19 A solid catalyst component was prepared in the same manner as in Example 14 modified in the following points.

(1) The ratio of magnesium chloride to silica charged was 2:3.

(2) Aluminum chloride was used in an amount of 0.92 g.

(3) Ethyl benzoate was used in an amount of 1.5 ml.

The resulting solid catalyst component contained 0.99 wt% titanium, 7.12 wt% magnesium and 26.7 wt% chlorine. A catalyst system comprising 0.4 mg (in terms of titanium atom) of the solid component, 1 70 mg of triethyl aluminum and 60 mg of ethyl p-toluate was used in polymerization of propylene following the procedure of Example 1. As a result, 214 g of a powdered polypropylene was produced. The polymer had a bulk density of 0.33 and an isotactic index of 93.6%. The yields of polymer per gram of titanium atom and MgCI2 were 535 kg and 1 9 kg, respectively. The theoretical residual chlorine content in the polymer was 49 ppm.

Example 20 The procedure of Example 14 was repeated to support magnesium chloride except that another silica gel (&num;3A, manufactured by Fuji Davison Chemical Ltd.) was used instead of silica gel &num;951 in preparation of the silica carrier and the weight ratio of magnesium chloride to silica was 2:3. The solid product was vacuum-dried under heating, treated with 0.5 g of aluminum chloride in dichloroethane, and washed. The washed product was mixed with 1.5 ml of ethyl benzoate and 50 ml of 1,2- dichloroethane containing 2.0 ml of titanium tetrachloride, and the mixture was heated under reflux for 2 hours with stirring. The stirring continued during subsequent cooling. The resulting solid was washed with n-hexane.The so prepared solid catalyst component contained 0.84 wt% titanium, 4.39 wt% magnesium, 1.24 wt% ethyl benzoate and 1 5.7 wt% chlorine. A catalyst system comprising 1 mg (in terms of titanium atom) of the solid component, 80 mg of triethyl aluminum and 27 mg of ethyl ptoluate was used in polymerization of propylene following the procedure of Example 1. As a result, 92 g of a powdered polypropylene was produced. The yields of the polymer per gram of titanium atom and MgCI2 were 92 kg and 4.5 kg, respectively. The isotactic index of the polymer was 91.7%. The polypropylene powder contained 3.2 wt% af fine particles less than 297 y in diameter, and the mean (50 wt%) particle size was about 1,000 y.

Example 21 Preparation of Solid Catalyst Component A mixture of 0.5 g of anhydrous magnesium chloride and 50 ml of dehydrated tetrahydrofuran was placed in a 200-ml three-necked flask, and 0.21 ml of titanium tetrachloride was added dropwise to the mixture under stirring. After the addition, the mixture was heated at 600C for 1 hour under stirring to dissolve the solid matter. To the solution, 6 g of the silica carrier prepared in Example 1 was added, and the mixture was heated at 600C for 1 hour. The mixture was dried by heating at 600C in an inert gas stream for about 3 hours to provide a freely flowable powder. The resulting solid catalyst component contained 1.28 wt% titanium and 2.17 wt% magnesium.

Polymerization of Ethylene An autoclave having an internal volume of 1 liter was charged with 500 ml of dehydrated industrial heptane, 100 mg of triethyl aluminum and 39 mg of the solid catalyst component. Ethylene was polymerized at 850C for 1 hour at a controlled total pressure of 9.0 kg/cm2 (4.5 kg/cm2 of hydrogen+4.5 kg/cm2 of ethylene). As a result, 65 g of a white powder of polyethylene was produced.

The yields of the polymer per gram of titanium atom and magnesium chloride per hour were 1 30 kg and 19.5 kg, respectively. The polyethylene powder had a particle size distribution data set forth below, Individual Cumulative Weight Weight Particle Size Percents Percents 74 y or less 4.0 4.0 74 to 105 y 2.9 6.9 105to149,u 1.1 8.0 149 to 297 u 17.3 25.3 297 to 500 y 37.0 62.3 500 to 840 y 28.7 91.0 840,*4 or more 9.0 100.0 Comparative Example 4 A solid catalyst component was prepared in the same manner as in Example 21 except that no chlorination treatment of silica gel with phosphorus pentachloride was conducted. The solid catalyst component contained 1.30 wt% titanium and 1.85 wt% magnesium.Polymerization of ethylene was conducted in the same manner as in Example 21 except that 31 mg of the solid catalyst component was used. Only trace amount of the desired polymer was obtained.

Example 22 A solid catalyst component was prepared in the same manner as in Example 21 except that dehydrated tetrahydrofuran was replaced by ethyl acetate. The resulting solid catalyst component contained 1.31 wt% titanium and 2.29 wt% magnesium. Polymerization of ethylene was conducted in the same manner as Example 21 except that 30.5 mg of the solid catalyst component was used. As a result, 1 5 g of a white powder of polyethylene was produced. The yields of the polymer per gram of titanium and magnesium chloride per hour were 38 kg and 5.6 kg, respectively.

Example 23 A 200-mi three-necked flask was filled with a mixture of the solid catalyst component prepared in Example 21, 1.1 g of aluminum chloride, 50 ml of 1,2-dichloroethane and 50 ml of normal hexane, and the mixture was heated at 650C for 1 hour under stirring. The solid content of the mixture was washed thoroughly with normal hexane. The resulting solid catalyst component contained 0.25% titanium and 2.95% magnesium. Polymerization of ethylene was conducted in the same manner as Example 21 except that 160 mg of the solid catalyst component was used. As a result, 41 g of a white powder of polyethylene was produced. The yields of the polymer per gram of titanium atom and magnesium chloride per hour were 10.3 kg and 2.2 kg, respectively.

Example 24 A mixture of 0.5 g of anhydrous magnesium chloride and 50 ml of dehydrated ethyl acetate was placed in a 200-ml three-necked flask, and the mixture was heated at 600C for 1 hour under stirring to dissolve the solid matter. To the solution, 6 g of a silica carrier used in Example 21 was added, and the mixture was heated at 600C for another 1 hour. The mixture was dried by heating at 600C for about 3 hours in an inert gas stream to provide a freely flowable powder. To the powder, 100 ml of titanium tetrachloride was added, and the mixture was heated at 800C for 2 hours under stirring. The mixture was let stand, and the solid matter was separated from the solution and washed thoroughly with normal hexane. The resulting solid catalyst component contained 1.07 wt% of titanium and 2.31 wt% of magnesium.

Polymerization of ethylene was conducted in the same manner as Example 21 except that 47 mg of the solid catalyst component was used. As a result, 13 g of a white powder of polyethylene was produced, The yields of the polymer per gram of titanium atom and magnesium chloride per hour were 25 kg and 2.9 kg, respectively.

Example 25 Preparation of Solid Catalyst Component The silica gel No. 951 as used in Example 1 was dried by calcination at 5000C for 5 hours. A 500-ml four-necked flask containing 300 ml of 1,2-dichloroethane was charged with 50 g of the calcined silica, and the mixture was supplied with chlorine gas for 5 hours at room temperature under stirring. The solid matter was separated from the solution, washed with 1,2-dichloroethane and dried under vacuum. The silica carrier contained 8.3% chlorine.

A mixture of 3 g of the silica carrier prepared above and 20 ml of dehydrated ethyl acetate containing 1 g of anhydrous magnesium chloride was charged into a 200-ml three-necked flask, and the mixture was slowly dried under vacuum to provide a silica carrier supporting magnesium chloride.

The carrier was dried and further heated to 1 300C while the residual solvent was removed under vacuum.

The solid powder was mixed with 0.4 g of anhydrous aluminum chloride and 100 ml of dichloroethane, and the mixture was heated under reflux for 2 hours with stirring. The mixture was then let stand. The solid content was separated from the solution and washed with dichloroethane. It was then mixed with 0.6 ml of ethyl benzoate and 50 ml of dichloroethane, and the mixture was heated under reflux for 2 hours under stirring. The mixture was then let stand. The solid matter was separated from the solution and mixed with 25 ml of titanium tetrachloride and 75 ml of dichloroethane. The mixture was heated under reflux for 2 hours with stirring. After standing, the solid matter was separated from the solution and washed with dichloroethane. The so prepared solid catalyst component (I) contained 0.84 wt% titanium, 6.09 wt% magnesium, 1.9 wt% ethyl benzoate, and 22.5 wt% chlorine.

Polymerization Into an autoclave having an internal volume of 1 liter, 0.5 mg (in terms of titanium atom) of the solid catalyst component was charged in a propylene stream. The autoclave was also charged with 75 mg of triethyl aluminum, 32.4 mg of ethyl p-toluate and 700 ml of liquefied propylene, and polymerization was performed at 700C for 1 hour.

As a result, 271 g of a white powder of polypropylene was produced. The polymer had an isotactic index of 92.2% and a bulk density of 0.39. The yields of polymer per gram of titanium atom and MgCI2 were 542 kg and 19.1 kg, respectively. The polypropylene powder comprised particles of uniform size and contained 1.9% of micro-fine particles less than 105 1 in diameter. Also, it was highly flowable as a powder.

Example 26 A mixture of 20 g of a silica gel (&num;951, manufactured by Fuji Davison Chemical Ltd.) which has been calcined at 5000C and 100 ml of benzotrichloride was charged into a 200-ml three-necked flask, and the mixture was heated at 1 300C for 14 hours under stirring. The mixture was washed and dried to provide a silica carrier containing 7.3% of chlorine.

Using this silica carrier, a solid catalyst component was prepared in the same manner as in Example 25. The resulting solid catalyst component contained 1.01 wt% titanium; 6.1 3 wt% of magnesium and 21.9% chlorine. The solid catalyst component was used in polymerization of propylene that was performed under the same conditions as in Example 25. As a result, 204.5 g of a powdered polypropylene was produced that had an isotactic index of 93.0% and a bulk density of 0.37. The yields of the polymer per gram of titanium atom and MgCI2 were 409 kg and 1 7.2 kg, respectively.

Example 27 A solid catalyst component was prepared by following the procedure of Example 25 modified in the following points.

(1) The mixing with the solution of aluminum chloride was replaced by mixing with 100 ml of titanium tetrachloride, and the mixture was heated at 1 300C for 2 hours.

(2) Ethyl benzoate was used in an amount of 1.25 ml.

The resulting solid catalyst component contained 1.45 wt% titanium, 4.80 wt% magnesium and 1.2 wt% ethyl benzoate. it had a BET surface area of 420 m2/g. A catalyst system comprising 1.0 mg (in terms of titanium atom) of the solid catalyst component, 80 mg of triethyl aluminum and 27.3 mg of ethyl p-toluate was used in polymerization of 700 ml of liquefied propylene following the procedure of Example 25. As a result, 230 g of polypropylene having an isotactic index of 90.3% and a bulk density of 0.32 was obtained. The yields of the polymer per gram of titanium atom and MgCI2 were 230 kg and 17.9 kg, respectively.

Example 28 A solid catalyst component was prepared by following the procedure of Example 27 modified in the following points.

(1) Instead of silica, an alumina (JRC-ALO-2, manufactured by Catalysis Society of Japan) was used as carrier. It was chlorinated to contain 12.9 wt% chlorine.

(2) 2 g of magnesium chloride was supported on the alumina.

(3) Ethyl benzoate was used in an amount of 1.5 ml.

The resulting solid catalyst contained 1.68 wP/O titanium,6.51 wt% magnesium and 2.2 wt% ethyl benzoate.

The solid catalyst component was used in polymerization of propylene that was performed under the same conditions as in Example 27. As a result, 259 g of polypropylene was produced. The polymer had an isotactic index of 88.8% and a bulk density of 0.40. The yields of the polymer per gram of titanium and MgCI2 were 259 kg and 17.1 kg, respectively.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Clams 1. A process for preparing an olefin polymer by a polymerization reaction wherein an olefin is contacted with a catalyst comprising: (1) a solid catalyst component composed of a magnesium halide, a titanium halogen compound, and an electron donor compound, supported on a metal oxide carrier containing silica, alumina, magnesia, titania or a mixed oxide thereof treated with a chlorinating agent; and (2) an organoaluminum compound.

2. The process according to Claim 1, wherein said chlorinating agent is phosphorus pentachloride, phosphorus trichloride, phosphorus dichloride, phosphorus oxytrichloride, chlorine or benzotrichloride.

3. The process according to Claim 1, wherein the titanium halogen compound is titanium tetrachloride.

4. The process according to Claim 1, wherein the electron donor compound is an aromatic monocarboxylic acid ester, a lower alkyl ether or an acetic ester.

5. The process according to Claim 1, 2, 3 or 4, wherein said solid catalyst component is prepared by dissolving a magnesium halide in a polar organic compound, bringing the solution into contact with a metal oxide treated with a chlorinating agent and thereafter contacting the treated metal oxide support with a titanium halogen compound and an electron donor compound.

6. The process according to Claim 1, 2, 3 or 4, wherein said solid catalyst component comprises a metal oxide carrier prepared by bringing a metal oxide treated with a chlorinating agent into contact with a magnesium halide.

7. The process according to Claim 6, wherein said solid catalyst component is prepared by bringing a metal oxide carrier treated with a chlorinating agent into contact with a solution including a complex of a magnesium halide and an electron donor compound substantially dissolved in a liquid titanium halogen compound.

8. The process according to Claim 1, 2, 3 or 4, wherein said solid catalyst component consists essentially of: (A) from 30 to 95 wt% of a metal oxide; (B) from 5 to 50 wt% of a magnesium halide; (C) from 0.1 to 20 wt% of an electron donor compound; and (D) from 2 to 30 wt% of a titanium halogen compound.

9. The process according to Claim 1, 2, 3 or 4, wherein said solid catalyst component consists essentially of: (A) from 35 to 90 wt% of a metal oxide; (B) from 10 to 40 wt% of a magnesium halide; (C) from 0.2 to 1 5 wt% of an electron donor compound; and (D) from 4 to 20 wt% of a titanium halogen compound.

10. The process according to Claim 1, 2, 3 or 4, wherein the organoaluminum compound is

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. titanium tetrachloride, and the mixture was heated at 1 300C for 2 hours. (2) Ethyl benzoate was used in an amount of 1.25 ml. The resulting solid catalyst component contained 1.45 wt% titanium, 4.80 wt% magnesium and 1.2 wt% ethyl benzoate. it had a BET surface area of 420 m2/g. A catalyst system comprising 1.0 mg (in terms of titanium atom) of the solid catalyst component, 80 mg of triethyl aluminum and 27.3 mg of ethyl p-toluate was used in polymerization of 700 ml of liquefied propylene following the procedure of Example 25. As a result, 230 g of polypropylene having an isotactic index of 90.3% and a bulk density of 0.32 was obtained. The yields of the polymer per gram of titanium atom and MgCI2 were 230 kg and 17.9 kg, respectively. Example 28 A solid catalyst component was prepared by following the procedure of Example 27 modified in the following points. (1) Instead of silica, an alumina (JRC-ALO-2, manufactured by Catalysis Society of Japan) was used as carrier. It was chlorinated to contain 12.9 wt% chlorine. (2) 2 g of magnesium chloride was supported on the alumina. (3) Ethyl benzoate was used in an amount of 1.5 ml. The resulting solid catalyst contained 1.68 wP/O titanium,6.51 wt% magnesium and 2.2 wt% ethyl benzoate. The solid catalyst component was used in polymerization of propylene that was performed under the same conditions as in Example 27. As a result, 259 g of polypropylene was produced. The polymer had an isotactic index of 88.8% and a bulk density of 0.40. The yields of the polymer per gram of titanium and MgCI2 were 259 kg and 17.1 kg, respectively. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. Clams

1. A process for preparing an olefin polymer by a polymerization reaction wherein an olefin is contacted with a catalyst comprising: (1) a solid catalyst component composed of a magnesium halide, a titanium halogen compound, and an electron donor compound, supported on a metal oxide carrier containing silica, alumina, magnesia, titania or a mixed oxide thereof treated with a chlorinating agent; and (2) an organoaluminum compound.

represented by the formula AIRnX3~n, wherein R is hydrogen or a hydrocarbon group having from 1 to 20 carbon atoms, X is a halogen, and n is an integer from 0 to 3.

11. The process according to Claim 1, 2, 3 or 4, wherein the organoaluminum compound is represented by the formula AlRnX3~n, wherein R is an alkyl group, an aralkyl group or an aryl group having from 1 to 20 carbon atoms, X is a halogen, and n is an integer from 0 to 3.

12. The process according to Claim 10, wherein X is chlorine or bromine.

13. The process according to Claim 11, wherein X is chlorine or bromine.

14. The process according to Claim 1, 2, 3 or 4, wherein the temperature at which the chlorinating treatment is conducted is from about 0 to 4000C.

1 5. The process according to Claim 14, wherein the temperature at which the chlorinating treatment is conducted is from about 30 to 2000C.

1 6. The process according to Claim 14, wherein the temperature at which the chlorinating treatment is conducted is from about 50 to 1 500C.

1 7. The process according to Claim 1, 2, 3 or 4, wherein the chlorinating treatment is carried out until the chlorine content is in the range of from about 0.05 to 20 wt% based on the weight of the chlorinated carrier.

1 8. The process according to Claim 1, 2, 3 or 4, wherein the chlorinating treatment is carried out until the chlorine content is in the range of from 0.5 to 1 8 wt%, based on the weight of the chlorinated carrier.

19. The process according to Claim 6, wherein the magnesium halide as used in an amount of from about 1 to 50 wt%, based on the weight of the carrier.

20. The process according to Claim 6, wherein the magnesium halide as used in an amount of from 3 to 20 wt%, based on the weight of the carrier.

21. The process according to Claim 6, wherein the carrier is subsequently treated with a Lewis acid.

22. A solid catalyst component composed of a magnesium halide, a titanium halogen compound, and an electron donor compound, supported on a metal oxide carrier containing silica, alumina, magnesia, titania or a mixed oxide is prepared by treatment thereof with a chlorinating agent.

23. A solid catalyst component as in Claim 22, wherein said chlorinating agent is phosphorus pentachloride, phosphorus trichloride, phosphorus dichloride, phosphorus oxytrichloride, chlorine or benzotrichloride.

24. A solid catalyst component as in Claim 22, wherein the titanium halogen compound is titanium tetrachloride.

25. A solid catalyst component as in Claim 22, wherein the electron donor compound is an aromatic monocarboxylic acid ester, a lower alkyl ether or an acetic ester.

26. A solid catalyst component as in Claim 22, 23, 24 or 25, wherein said solid catalyst component is prepared by dissolving a magnesium halide in a polar organic compound, bringing the solution into contact with a metal oxide treated with a chlorinating agent, and thereafter contacting the treated metal oxide support with a titanium halogen compound and an electron donor compound.

27. A solid catalyst component as in Claim 22, 23, 24, or 25, wherein said solid catalyst component comprises a metal oxide carrier prepared by bringing a metal oxide treated with a chlorinating agent into contact with a magnesium halide.

28. A solid catalyst component as in Claim 7, wherein said solid catalyst component is prepared by bringing a metal oxide carrier treated with a chlorinating agent into contact with a solution including a complex of a magnesium halide and an electron donor compound substantially dissolved in a liquid titanium halogen compound.

29. A solid catalyst component as in Claim 22, 23, 24 or 25, wherein said solid catalyst component consists essentially of: (A) from 30 to 95 wt% of a metal oxide; (B) from 5 to 50 wt% of a magnesium halide; (C) from 0.1 to 20 wt% of an electron donor compound; and (D) from 2 to 30 wt% of a titanium halogen compound.

30. A solid catalyst component as in Claim 22, 23, 24 or 25, wherein said solid catalyst component consists essentially of: (A) from 35 to 90 wt% of a metal oxide; (B) from 10 to 40 wt% of a magnesium halide; (C) from 0.2 to 15 wt% of an electron donor compound; and (D) from 4 to 20 wt% of a titanium halogen compound.

31. A process as claimed in Claim 1 for preparing an olefin polymer substantially as hereinbefore described with reference to any one of the Examples.

32. An olefin polymer prepared by a process as claimed in any one of Claims 1-21 or Claim 31.

33. A solid catalyst component as claimed in Claim 22, substantially as hereinbefore described with reference to any one of the Examples.