GB2135681A - Ziegler catalysed olefin polymerisation - Google Patents

Abstract

Olefin is polymerized using a catalyst which comprises the combination of: [I] a solid substance obtained by the reaction of at least the following two components: (i) a magnesium halide and (ii) a titanium compound and/or a vanadium compound; [II] a compound represented by the general formula R<1>mSi(OR<2>)4-m wherein R<1> and R<2> are hydrocarbon radicals having 1 to 24 carbon atoms and 0</=m</=3; [III] a compound represented by the general formula R<3>nAl(OR<4>)3-n wherein R<3> and R<4> are hydrocarbon radicals having 1 to 24 carbon atoms and 1</=n</=2; and [IV] an organometallic compound, the molar ratio of silicon in said component [II] to titanium and/or vanadium in said component [III] being in the range of 0.1 to 100, the molar ratio of aluminum in said component [III] to silicon in said component [II] being in the range of 0.01 to 10 and the molar ratio of the metal in said component [IV] to titanium and/or vanadium in said component [I] being in the range of 0.1 to 1,000.

Description

SPECIFICATION Process for preparing polyolefins Background of the Invention The present invention relates to a process for preparing polyolefins using a novel polymerization catalyst.

Heretofore, in the technical field of this sort there has been known from Japanese Patent Publication No. 12105/1 964 a catalyst comprising a magnesium halide and a transition metal compound such as a titanium compound supported thereon. Further, a catalyst obtained by the copulverization of a magnesium halide and titanium tetrachloride is known from Belgian Patent No.

742,112.

However, when viewed from the standpoint that the catalyst activity is desired to be as high as possible in the manufacture of polyolefins, the process disclosed in the Japanese Patent Publication No. 12105/1964 is still unsatisfactory because of a low polymerization activity, while the polymerization activity attained in the process of Belgian Patent 742,112 is fairly high, but a further improvement is desired.

In the process disclosed in German Patent No. 2137872, the amount of a magnesium halide used is substantially decreased by the co-pulverization thereof with titanium tetrachloride and alumina, but a remarkable increase in activity per solid, which can be recognized as a guideline for productivity, is not recognized, and it is desired to develop a catalyst of a higher activity.

In the manufacture of polyolefins, moreover, it is also desirable from the aspects of productivity and slurry handling that the bulk density of the resulting polymer be as high as possible. From this standpoint, the process disclosed in the Japanese Patent Publication No. 12105/1964 is not satisfactory in both the bulk density of the resulting polymer and polymerization activity, while in the process disclosed in the Belgian Patent 742,112, the polymerization activity is high, but the bulk density of the resulting polymer is low. Thus, in both the processes, a further improvement is desired.

Summary of the Invention The present invention provides a novel polymerization catalyst and a process for the homopolymerization or copolymerization of olefins using the catalyst, capable of remedying the abovementioned drawbacks, attaining a high polymerization activity, affording polymers with a high bulk density in high yield and continuous polymerization extremely easily.

The present invention resides in a process for preparing polyolefins by the homopolymerization or copolymerization of olefins using a catalyst which comprises the combination of: [I] a solid substance obtained by the reaction of at least the following two components: (i) a magnesium halide and (ii) a titanium compound and/or a vanadium compound; [II] a compound represented by the general formula R'mSi(OR2)4~m wherein R1 and R2 are hydrocarbon radicals having 1 to 24 carbon atoms and 06m3; [III] a compound represented by the general formula R3nAl(OR4)3~n wherein R3 and R4 are hydrocarbon radicals having 1 to 24 carbon atoms and 1 ~n < 2;; and [IV] an organometallic compound, and which catalyst satisfies the conditions that the molar ratio of silicon in the component [II] to titanium and/or vanadium in the component [I] should be in the range of 0.1 to 100, the molar ratio of aluminum in the component [III] to silicon in the component [II] should be in the range of 0.01 to 10 and the molar ratio of the metal in the component [IV] to titanium and/or vanadium in the component [I] should be in the range of 0.1 to 1000.

Since the polymerization catalyst used in the present invention exhibits a very high polymerization activity, the partial pressure of monomer during polymerization is low, and because of a high bulk density of the resulting polymer, the productivity can be improved. Moreover, the amount of the catalyst remaining in the resulting polymer after polymerization is so small that the polyolefin manufacturing process can dispense with the catalyst removing step, which leads to simplification of the polymer treating step, and consequently polyolefins can be prepared very economically.

According to the process of the present invention, the amount of polymer produced per unit polymerization reactor is large because of a high bulk density of the resulting polymer.

The present invention is further advantageous in that when viewed from the standpoint of particle size of the resulting polymer, the proportion of coarse particles and that of fine particles below 50 Mm are small despite a high bulk density of the polymer, and that therefore not only it becomes easy to perform a continuous polymerization reaction but also the centrifugal separation in the polymer treating step as well as the handling of polymer particles in powder transport become easy.

According to the present invention, in addition to the high bulk density of polyolefins obtained by using the catalyst of the invention as previously noted, polyolefins having a desired melt index can be prepared at a lower hydrogen concentration than in conventional methods, thus permitting polymerization to be carried out at a relatively small total pressure, and this greatly contributes to the improvement of economy and productivity.

Additionally, in the olefin polymerization using the catalyst of the present invention, the olefin absorbing rate does not decrease so much even with lapse of time, and therefore the polymerization can be conducted for a long time in a small amount of the catalyst.

Furthermore, polymers prepared by using the catalyst of the present invention have a very narrow molecular weight distribution and their hexane extraction is very small, reflecting minimized byproduction of low grade polymers. Therefore, for example, in the film grade, these polymers can afford products of good quality such as a superior antiblocking property.

Description of Preferred Embodiments Examples of the magnesium halide used in the present invention include substantially anhydrous magnesium fluoride, magnesium chloride, magnesium bromide, magnesium iodide, and mixtures thereof, with magnesium chloride being most preferable.

Examples of the titanium compound and/or vanadium compound used in the present invention include halides, alkoxyhalides, alkoxides and halogenated oxides, of titanium and/or vanadium. As preferred examples of the titanium compound there may be mentioned tetravalent and trivalent titanium compounds.As tetravalent titanium compounds, those represented by the general formula Ti(OR)X4~, are preferred wherein R is an alkyl, aryl or aralkyl group having 1 to 24 carbon atoms, X is a halogen atom and r is O < r~4, such as titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxymonochlorotitanium, diethoxydichlorotitanium, tetramethoxytitanium, monoethoxytrichlorotitanium, triethoxymonochlorotitanium, tetraethoxytitanium, monoisopropoxytrichlorotitanium, diisopropoxy dichlorotitani um, triisopropoxymonochlorotitanium, tetraisopropoxytitanium, monobutoxytrichlorotitanium, dibutoxydichlorotitanium, monopentoxytrichlorotitanium, monophenoxytrichlorotitanium, diphenoxydichlorotitanium, triphenoxymonochlorotitanium and tetraphenoxytitanium. As trivalent titanium compounds there may be used, for example, titanium trihalides obtained by reducing titanium tetrahalides such as titanium tetrachloride and titanium tetrabromide with hydrogen, aluminum, titanium or an organometallic compound of a metal selected from Groups I through III in the Periodic Table, as well as trivalent titanium compounds obtained by reducing tetravalent alkoxytitanium halides of the general formula Ti(OR)sX4~s with an organometallic compound of a metal selected from Groups I through Ill in the Periodic Table in which formula R is an alkyl, aryl or aralkyl group having 1 to 24 carbon atoms, Xis a halogen atom and s is O < s < 4. Examples of the vanadium compound include tetravalent vanadium compounds such as vanadium tetrachloride, vanadium tetrabromide, vanadium tetraiodide and tetraethoxyvanadium; pentavalent vanadium compounds such as vanadium oxytrichloride, ethoxydichlorovanadyl, triethoxyvanadyl and tributoxyvanadyl; and trivalent vanadium compounds such as vanadium trichloride and vanadium triethoxide. Tetravalent titanium compounds are most preferable in the present invention.

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

The method of obtaining the catalyst component [I] by reacting the magnesium halide (i) with the titanium compound and/or vanadium compound (ii) in the present invention is not specially limited.

Both (i) and (ii) may be reacted by contacting together usually for 5 minutes to 20 hours under heating at a temperature of 200 to 4000 C, preferably 500 to 3000C, in the presence or absence of an inert solvent. Alternatively, the reaction may be carried out by a co-pulverization treatment. The latter is preferable in the present invention.

The inert solvent which may be used in preparing the catalyst component [I] is not specially limited. Hydrocarbons and/or derivatives thereof not inactivating Ziegler type catalysts are usually employable. Examples are various saturated aliphatic hydrocarbons, aromatic hydrocarbons and alicyclic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, benzene, toluene, xylene and cyclohexane, as well as alcohols, ethers and esters such as ethanol, diethyl ether, tetrahydrofuran, ethyl acetate and ethyl benzoate.

The apparatus to be used for the co-pulverization is not specially limited. Usually, a ball mill, a vibration mill, a rod mill or an impact mill is used. Conditions for the co-pulverization such as temperature and time can be decided easily by those skilled in the art according to the co-pulverization method used. In general, the co-pulverization is carried out at a temperature in the range of 0 to 2000 C, preferably 200 to 1000C, for a period of time in the range of 0.5 to 50 hours, preferably 1 to 30 hours. Of course, the co-pulverizing operation should be performed in an inert gas atmosphere, and moisture should be avoided.

As to the reaction ratio of the magnesium halide and the titanium compound and/or vanadium compound, it is most preferable to adjust it so that the amount of titanium and/or vanadium contained in the catalyst component [I] is in the range of 0.5 to 20 wt.%. The range of 1 to 10 wt.% is particularly preferred in order to attain a well-balanced activity per titanium and/or vanadium and that per solid.

In preparing the catalyst component [I] in the present invention, moreover, a member or members selected from the group consisting of compounds of the general formula Me(OR)pXz~p wherein Me is an element selected from Groups I through VIII in the Periodic Table, provided titanium and vanadium are excluded, R is a hydrocarbon radical having 1 to 24 carbon atoms, X is a halogen atom, z is the valence of Me and p is O < p < z, organic halides, halogenating agents, phosphoric esters, electron donors and polycyclic aromatic compounds may also preferably be used as component (a) in addition to the magnesium halide (i) and the titanium compound and/or vanadium compound (ii). The component (a) may be used in an amount of 0.01 to 5 moles, preferably 0.05 to 2 moles, per mole of the magnesium halide (i).

Examples of compounds of the general formula Me(OR)pXz~p which may be used in the present invention include the following compounds: NaOR, Mg(OR)2, Mg(OR)X, Ca(OR)2, Zn(OR)2, Zn{OR)X, Cd(OR)2, Al(OR)3, Al(OR)2X, B(OR)3, B(OR)2X, Ga(OR)3, Ge(OR)4, Sn(OR)4, P(OR)3, Cr(OR)2, Mn(OR)2, Fe(OR)2, Fe(OR)3, Co(OR)2 and Ni(OR)2.As more concrete preferable examples there may be mentioned the following compounds: NaOC,H,, NaOC4Hg, Mg(OCH3)2, Mg(0C2H5)2, Mg(OC3H7)2, Ca(OC2H5)2, Zn(OC2H5)2, Zn(OC2Hs)CI, Al(OCH3)3, Al(OC2H5)3, Al(OC2H5)2CI, Al(OC3H7)3, Al(OC4H9)3, Al(OC6H5)3, B(OC2H5)3, B(OC2H5)2CI, P(OC2H5)3t P(OC6H5)3 and Fe(OC4Hg)3.

Particularly, compounds represented by the general formulae Mg(OR)pX2~p, Al(OR)pX3~p and B(OR)pX3~p are preferred. As the substituent B, C1 to C4 alkyl groups and phenyl are preferred.

Organic halides which may be used in the present invention are partially halogen-substituted, saturated or unsaturated aliphatic and aromatic hydrocarbons, including mono-, di- and tri-substituted compounds. The halogen may be any of fluorine, chlorine, bromine and iodine.

Examples of such organic halides include methylene chloride, chloroform, carbon tetrachloride, bromochloromethane, dichlorodifluoromethane, 1 -bromo-2-chloroethane, chloroethane, 1 ,2-dibromo- 1,1 -dichloroethane, 1 , 1 -dichloroethane, 1 ,2-dichloroethane, 1 ,2-dichloro-1 , 1 ,2,2-tetrafluoroethane, hexachloroethane, pentachloroethane, 1,1,1 ,2-tetrachloroethane, 1.1 .2,2-tetrachloroethane, 1,1,1- trichloroethane, 1,1 ,2-trichloroethane, 1 -chloropropane, 2-chloropropane, 1 ,2-dichloropropane, 1,3- dichloropropane,2,2-dichloropropane, 1,1,1,2,2,3,3-heptachloropropane, 1,1,2,2,3,3- hexachloropropane, octachloropropane, 1 1 ,2-trichloropropane, 1 -chlorobutane, 2-chlorobutane, 1 - ch loro-2-methyl propane,2-ch 2-chloro-2-methylpropane, 1 ,2-dichlorobutane, 1 ,3-dichlorobutane, 1 ,4- dichlorobutane, 2,2-dichlorobutane, 1 -chlorodecane, vinyi chloride, 1 ,1 -dichloroethylene, 1,2- dichloroethylene, tetrachloroethylone, 3-chloro-1 -propene, 1 3-dichloropropene, chloroprene, oleyl chloride, chlorobenzene, chloronaphthalene, benzyl chloride, benzylidene chloride, chloroethylbenzene, styrene dichloride and a-chlorocumene.

Examples of halogenating agents which may be used in the present invention include halides of nonmetals such as sulfur chloride, PAL3, PCl5 and SiC14, as well as oxyhalides of nonmetals such as POCI3, COCK2, NOCI2, SOCI2 and SO2Cl2.

Phosphoric esters which may be used in the present invention are compounds represented by the general formula

wherein the Rs may be alike or different and each R is a hydrocarbon radical having 1 to 24 carbon atoms. Examples of such compounds are triethyl phosphate, tri-n-butyl phosphate, triphenyl phosphate, tribenzyl phosphate, trioctyl phosphate, tricresyl phosphate, tritolyl phosphate, trixylyl phosphate and diphenylxylenyl phosphate.

Examples of electron donors which may be used in the present invention are alcohols, ethers, ketones, aldehydes, organic acids, organic acid esters, acid halides, acid amides, amines and nitriles.

As alcohols there may be used, for example, those having 1 to 1 8 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, allyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, t-butyl alcohol, n-amyl alcohol, n-hexyl alcohol, cyclohexyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, benzyl alcohol, naphthyl alcohol, phenol and cresol.

As ethers there may be used, for example, those having 2 to 20 carbon atoms such as dimethyl ether, diethyl ether, dibutyl ether, isoamyl ether, anisole, phenetole, diphenyl ether, phenylallyl ether and benzofuran.

As ketones there may be used, for example, those having 3 to 1 8 carbon atoms such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl phenyl ketone, ethyl phenyl ketone and diphenyl ketone.

As aldehydes there may be used, for example, those having 2 to 1 5 carbon atoms such as acetaldehyde, propinaldehyde, octylaldehyde, benzaldehyde and naphthaldehyde.

As organic acids there may be used, for example, those having 1 to 24 carbon atoms such as formic, acetic, propionic, butyric, valeric, pivalic, caproic, caprylic, stearic, oxalic, malonic, succinic, adipic, methacrylic, benzoic, toluic, anisic, oleic, linoleic and linolenic acids As organic esters there may be used, for example, those having 2 to 30 carbon atoms such as methyl format, methyl acetate, ethyl acetate, propyl acetate, octyl acetate, ethyl propionate, methyl butyrate, ethyl valerate, methyl methacrylate, methyl benzoate, ethyl benzoate, propyl benzoate, octyl benzoate, phenyl benzoate, benzyl benzoate, butyl ethoxybenzoate, methyl toluylate, ethyl toluylate, ethyl ethylbenzoate, methyl salitylate, phenyl salitylate, methyl naphthoate, ethyl naphthoate and ethyl anisate.

As acid halides there may be used, for example, those having 2 to 1 5 carbon atoms such as acetyl chloride, benzoyl chloride, toluoyl chloride and anisoyl chloride.

As acid amides there may be used, for example, acetamide, benzoylamide and toluoylamide.

As amines there may be used, for example, methylamine, ethylamine, diethylamine, tributylamine, piperidine, tribenzyiamine, aniline, pyridine, picoline and tetramethylenediamine.

As nitriles there may be used, for example, acetonitrile, benzonitrile and tolunitriie.

Examples of polycyclic aromatic compounds which may be used in the present invention include naphthalene, phenanthrene, triphenylene, chrysene,3,4-benzophenanthrene,1,2-benzochrysene, picene, anthracene, tetraphene, 1 ,2,3,4-dibenzanthracene, pentaphene, 3,4-benzopentaphene, tethracene, 1 ,2-benzotethracene, hexaphene, heptaphene, diphenyl, fluorene, biphenylene, perylene, coronene, bisantene, ovalene, pyrene and perinaphthene, as well as halogen- and alkyl-substituted derivatives thereof.

The catalyst component [I] thus obtained may be supported on an oxide of a metal selected from Groups II through IV in the Periodic Table. This mode of use is also preferable in the present invention.

In this case, not only oxides of Group lI-IV metals each alone but also double oxides of these metals, as well as mixtures thereof, are employable. Examples of such metal oxides are MgO, CaO, ZnO, BaO, SiO2, SnO2, Al203, MgO Awl203, SiO2 Al203, MgO SiO2, MgO CaO AI203 and At203 CaO.

Particularly preferred are Ski02, Al20S, SiO, . Al203 and MgO A120 .

The method of supporting the catalyst component [il on an oxide of a Group lI-IV metal in the Periodic Table is not specially limited, but as a preferred example there may be mentioned a method wherein the components (i) and (ii), and the component (a) if required, are allowed to react under heating, for example in an ether compound as solvent in the presence of the said metal oxide and then the liquid phase portion is removed.

Examples of the compound of the general formula R'mSi(OR2)4~m used in the present invention include monomethyl trimethoxy silane, monomethyl triethoxy silane, monomethyl tri-n-butoxy silane, monomethyl tri-sec-butoxy silane, monomethyl triisopropoxy silane, monomethyl tripentoxy silane, monomethyl trioctoxy silane, monomethyl tristearoxy silane, monomethyl triphenoxy silane, dimethyl dimethoxy silane, dimethyl diethoxy silane, dimethyl diisopropoxy silane, dimethyl diphenoxy silane, trimethyl monomethoxy silane, trimethyl monoethoxy silane, trimethyl monoisopropoxy silane, trimethyl monophenoxy silane, monoethyl trimethoxy silane, monoethyl triethoxy silane, monoethyl triisopropoxy silane, monoethyl triphenoxy silane, diethyl dimethoxy silane, diethyl diethoxy silane, diethyl diphenoxy silane, triethyi monomethoxy silane, triethyl monoethoxy silane, triethyl monophenoxy silane, monoisopropyl trimethoxy silane, mono-n-butyl trimethoxy silane, mono-n-butyl triethoxy silane, mono-sec-butyl triethoxy silane, monophenyl triethoxy silane, diphenyl diethoxy silane, tetraethoxy silane and tetraisopropoxy silane.

If the amount of the compound of the general formula RamSi(OR2)4~m used in the present invention is too large or too small, its effect of addition cannot be expected. Usually, its amount is in the range of 0.1 to 100 moles, preferably 0.3 to 20 moles, per mole of the titanium compound and/or vanadium compound in the catalyst component [I].

As examples of the compound of the general formula R'nAl(OR4)3~n used in the present invention, mention may be made of the following: dimethylaluminum monoethoxide, dimethylaluminum monoisopropoxide, dimethylaluminum mono-n-butoxide, dimethylaluminum sec-butoxide, dimethylaluminum monophenoxide, diethylaluminum monomethoxide, diethylaluminum monoethoxide, diethylaluminum monoisopropoxide, diethylaluminum mono-n-butoxide, diethylaluminum sec-butoxide, diethylaluminum monophenoxide, diethylaluminum monooctoxide, diethylaluminum monostearyloxide, diisobutylaluminum monoethoxide, methylaluminum dimethoxide, methylaluminum diethoxide, ethylaluminum dimethoxide, ethylaluminum diethoxide, ethylaluminum diisopropoxide, ethylaluminum di-n-butoxide, ethylaluminum phenoxide, isobutylaluminum dimethoxide and isobutyl aluminum diethoxide.

As to the amount of the compound of the general formula R4nAl(OR4)3~n used in the present invention, both a too large amount an.d a too small amount would not be effective. Its amount is in the range of 0.01 to 10 moles, preferably 0.05 to 2 moles, per mole of the silicon compound in the catalyst component [Il].

As examples of the organometallic compound used in the present invention, there may be mentioned organometallic compounds of Group I-lV metals in the Periodic Table known as a component of Ziegler type catalysts, but organoaluminum compounds and organozinc compounds are particularly preferred, for example, organoaluminum compounds of the general formulae R3AI, R2AIX, RAIX2 and R3AI2X3 wherein R, which may be alike or different, is an alkyl or aryl group having 1 to 20 carbon atoms and X is a halogen atom, and organozinc compounds of the general formula R2Zn wherein R, which may be alike or different, is an alkyl group having 1 to 20 carbon atoms, such as triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-sec-butylaluminum, tri-tertbutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, diethylaluminum chloride, diisopropylaluminum chloride, ethylaluminum sesquichloride, diethylzinc, and mixtures thereof.

Together with these organometallic compounds there may be used organocarboxylic acid esters such as ethyl benzoate, ethyl toluylate and ethyl anisate. The organometallic compound may be used in an amount of 0.1 to 1,000 moles per mole of the titanium compound and/or vanadium compound in the catalyst component [I].

The olefin polymerization using the catalyst of the present invention may be carried out by slurry polymerization, solution polymerization or vapor phase polymerization. Particularly, slurry polymerization and vapor phase polymerization are preferred. The polymerization reaction is carried out in the same way as in the conventional olefin polymerization reaction using a Ziegler type catalyst. That is, the reaction is performed in a substantially oxygen- and water-free condition and in the presence or absence of an inert hydrocarbon. Olefin polymerizing conditions involve temperatures in the range of 200 to 1 200 C, preferably 500 to 1000C, and pressures in the range of atmospheric pressure to 70 kg/cm2, preferably 2 to 60 kg/cm2.Adjustment of the molecular weight can be made to some extent by changing polymerization conditions such as the polymerization temperature and the catalyst mole ratio, but the addition of hydrogen into the polymerization system is more effective for this purpose. Of course, using the catalyst of the present invention, two or more multi-stage polymerization reactions having different polymerization conditions such as different hydrogen concentrations and different polymerization temperatures can be performed without any trouble.

The process of the present invention is applicable to the polymerization of all olefins that are polymerizable with a Ziegler type catalyst. Particularly, a-olefins having 2 to 12 carbon atoms are preferred. For example, the process of the present invention is suitable for the homopolymerization of such a-olefins as ethylene, propylene, butene-1, hexene-1, 4-methylpentene-1 and octene-1 , the copolymerization of ethylene/propylene, ethylene/butene-1, ethylene/hexene-1, ethylene/4methylpentene-1, ethylene/octene-1 and propylene/butene-1, as well as the copolymerization of ethylene and two or more ether a-olefins.

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

The following examples are given to further illustrate the present invention, but it is to be understood that the invention is not limited thereto.

EXAMPLE 1 (a) Preparation of Solid Catalyst Component [I] 10 g. of a commercially available anhydrous magnesium chloride, 2.3 g. cf aluminum triethoxide and 2.5 g. of titanium tetrachloride were placed in a stainless steel pot having a content volume of 400 ml. and containing 25 stainless steel balls each 1/2 inch in diameter, and ball-milled for 16 hours at room temperature in a nitrogen atmosphere, to obtain a solid catalyst component [I] containing 41 mg of titanium per gram thereof.

(b) Polymerization A 2-liter stainless steel autoclave equipped with an induction stirrer was purged with nitrogen and then charged with 1,000 ml. of hexane, then 1 mmol. of triethylaluminum, 0.05 mmol. of diethyl diethoxysilane, 0.01 mmol. of diethylaluminum monoethoxide and 10 mg. of the above solid catalyst component [I] were added and the temperature was raised to 900C under stirring. With the vapor pressure of hexane, the system was pressurized to 2 kg/cm2G. Then, hydrogen was introduced up to a total pressure of 4.8 kg/cm2 G and then ethylene was introduced up to a total pressure of 10 kg/cm2 G. In this state, polymerization was allowed to start, which was continued for 1 hour while maintaining the internal pressure of the autoclave at 10 kg/cm2 G.Thereafter, the polymer slurry was transferred into a beaker and hexane was removed under reduced pressure to obtain 1 75 g. of a white polyethylene having a melt index of 1.1 and a bulk density of 0.38. Catalytic activity was 82,100 g.

polyethylene/g. Ti hr. C2H4 pressure, 3,370 g. polyethylene/g. solid hr C2H4 pressure.

F.R. value* of the polyethylene thus obtained was 7.5. The molecular weight distribution was extremely narrow as compared with the following comparative Example 1.

*F.R. value represents the extent of molecular weight distribution and is calculated as follows: F.R.=melt index at 10 kg. load/melt index at 2.16 kg. load The melt index was measured according to ASTM D-1 238.

Comparative Example 1 Polymerization of ethylene was carried out in the same way as in Example 1 except that the diethylaluminum monoethoxide was not used, to obtain 140 g. of a white polyethylene having a bulk density of 0.33 and a melt index of 1.0. Catalytic activity was 65,700 g. polyethylene/g. Ti hr C2H4 pressure, 2,700 g. polyethylene/g. solid hr. C2H4 pressure. The F.R. value of the polyethylene was 8.0.

EXAMPLE 2 Polymerization of ethylene was carried out in the same way as in Example 1 except that 0.05 mmol. of monoethyl triethoxy silane was used in place of the diethyl diethoxy silane and that the amount of the diethylaluminum monoethoxide was changed to 0.02 mmol. As a result, there was obtained 1 63 g. of a white polyethylene having a melt index of 0.9 and a bulk density of 0.41. Catalytic activity was 76,500 g. polyethylene/g. Ti hr C2H4 pressure, 3,130 g. polyethylene/g. solid hr C2H4 pressure.

The F.R. value of the polyethylene thus obtained was 7.4. The molecular weight distribution was extremely narrow as compared with the following Comparative Example 2.

Comparative Example 2 Polymerization of ethylene was carried out in the same way as in Example 2 except that the diethylaluminum monoethoxide was not used. As a result, there was obtained 121 g. of a white polyethylene having a melt index of 1.1 and a bulk density of 0.32. Catalytic activity was 56,800 g.

polyethylene/g. Ti hr C2H4 pressure, 2,330 g. polyethylene/g. solid hr C2H4 pressure. The F.R. value of the polyethylene was 8.1.

EXAMPLE 3 Polymerization of ethylene was carried out in the same way as in Example 1 except that 0.1 mmol. of diphenyl diethoxy silane and 0.02 mmol. of ethylaluminum diphenoxide were used in place of the diethyl diethoxy silane and diethylaluminum monoethoxide, respectively. As a result, there was obtained 181 g. of a white polyethylene having a melt index of 1.3 and a bulk density of 0.39. Catalytic activity was 84,900 g. polyethylene/g. Ti hr C2H4 pressure, 3,480 g. polyethylene/g. solid hr. C2H4 pressure. The F.R. value of the polyethylene was 7.5. The molecular weight distribution was extremely narrow as compared with the following Comparative Example 3.

Comparative Example 3 Polymerization of ethylene was carried out in the same way as in Example 3 except that the ethylaluminum diphenoxide was not used. As a result, there was obtained 133 g. of a white polyethylene having a melt index of 1.0 and a bulk density of 0.33. Catalytic activity was 62,400 g.

polyethyiene/g. Ti hr C2H4 pressure, 2,560 g. poiyethylene/g. solid hr C2H4 pressure. The F.R. value of the polyethylene was 8.0.

EXAMPLE 4 (a) Preparation of Solid Catalyst Component [I] 10 g. of a commercially available magnesium chloride and 4.2 g. of aluminum triethoxide were placed in a stainless steel pot having a content volume of 400 ml. and containing 25 stainless steel balls each 1/2 inch in diameter, and ball-milled for 16 hours at room temperature in a nitrogen atmosphere to obtain a reaction product. Then, a three-necked flask equipped with a stirrer and a reflux condenser was purged with nitrogen and then charged with 5 g. of the above reaction product and 5 g.

of silica (&num;952, a product of Fuji-Davison) which had been calcined at 6000 C. Then, 1 00 ml. of tetrahydrofuran was added and reaction was allowed to take place at 600C for 2 hours. Thereafter, tetrahydrofuran was removed by drying at 1 200C under reduced pressure. Then, 50 ml. of hexane was added, and after stirring, 1.1 ml. of titanium tetrachloride was added and reaction was allowed to take place for 2 hours under reflux of hexane to give a solid powder (A) containing 40 mg. of titanium per gram thereof.

The solid powder (A) was added into 50 ml. of hexane, then 1 ml. of tetraethoxy silane was added and reaction was allowed to take place for 2 hours under reflux of hexane to obtain a solid catalyst component [I].

(b) Polymerization A 2-liter stainless steel autoclave equipped with an induction stirrer was purged with nitrogen and then charged with 1,000 ml. of hexane, then 1 mmol. of triethylaluminum, 0.05 mmol. of dimethyl diethoxy silane, 0.01 mmol. of diethylaluminum monoethoxide and 10 mg. of the above solid catalyst component [I] were added and the temperature was raised to 900C under stirring. With the vapor pressure of hexane, the system was pressurized to 2 kg/cm2 G. Then, hydrogen was introduced up to a total pressure of 4.8 kg/cm2 G and then ethylene was introduced up to a total pressure of 10 kg/cm2 G. In this state, polymerization was allowed to start, which was continued for 1 hour while maintaining the internal pressure of the autoclave at 10 kg/cm2 G. Thereafter, the polymer slurry was transferred into a beaker and hexane was removed under reduced pressure to give 60 g. of a white polyethylene having a melt index of 0.7 and a bulk density of 0.42. Catalytic activity was 28,800 g.

polyethylene/g. Ti hr C2H4 pressure,1,150 g. polyethylene/g. solid hr. C2H4 pressure. The F.R. value of the polyethylene was 7.4. The molecular weight distribution was extremely narrow as compared with the following Comparative Example 4. Further, the polymer particles proved to be superior in fluidity and have an average particle diameter of 730 ym.

Comparative Example 4 Polymerization of ethylene was carried out in the same way as in Example 4 except that the diethylaluminum monoethoxide was not used. As a result, there was obtained 48 g. of polyethylene having a melt index of 0.9 and a bulk density of 0.34. Catalytic activity was 23,100 g. polyethylene/g.

Ti hr C2H4 pressure, 920 g. polyethylene/g. solid hr. C2H4 pressure. The F.R. value of the polyethylene was 8.1.

EXAMPLE 5 (a) Preparation of Solid Catalyst Component [I] 10 g. of a commercially available anhydrous magnesium chloride, 2.0 g. of titanium tetraisopropoxide and 1.7 g. of isopropyl chloride were placed in a stainless steel pot having a content volume of 400 ml. and containing 25 stainless steel balls each 1/2 inch in diameter, and ball-milled for 1 6 hours at room temperature in a nitrogen atmosphere, to give a solid catalyst component [I] containing 25 mg. of titanium per gram thereof.

(b) Polymerization A 2-liter stainless steel autoclave equipped with an induction stirrer was purged with nitrogen and then charged with 1,000 ml. of hexane, then 1 mmol. of triethylaluminum, 0.1 mmol. of diphenyl diethoxy silane, 0.05 mmol. of diethylaluminum monoethoxide and 10 mg. of the above solid catalyst component [I] were added and the temperature was raised to 900C under stirring. With the vapor pressure of hexane, the system was pressurized to 2 kg/cm2 G. Then, hydrogen was introduced up to a total pressure of 4.8 kg/cm2 G and then ethylene was introduced up to a total pressure of 10 kg/cm2 G. In this state, polymerization was allowed to start, which was continued for 1 hour while maintaining the total pressure at 10 kg/cm2 G.Thereafter, the polymer slurry was transferred into a beaker and hexane was removed under reduced pressure to afford 44 g. of a white polyethylene having a melt index of 1.1 and a bulk density of 0.38. Catalytic activity was 33,700 g. polyethylene/g.

Ti hr. C2H4 pressure, 850 g. polyethylene/g. solid hr. C2H4 pressure. The F.R. value was 7.6 and thus the molecular weight distribution was narrow.

Comparative Example 4 Polymerization of ethylene was carried out in the same way as in Example 5 except that the diethylaluminum monoethoxide was not used. As a result, there was obtained 35 g. of polyethylene having a melt index of 0.9 and a bulk density of 0.31. Catalytic activity was 26,800 g. polyethylene/g.

Ti hr C2H4 pressure, 670 g. polyethylene/g. solid hr. C2H4 pressure. The F.R. value was 8.2.

EXAMPLE 6 A vapor-phase polymerization was carried out using the solid catalyst component [I] obtained in Example 1. As the vapor-phase polymerization apparatus there was used a stainless steel autoclave, and a loop was formed by a blower, a flow control device and a dry cyclone. The temperature of the autoclave was adjusted by passing warm water through its jacket.

Into the autoclave adjusted to 80CC were fed the solid catalyst component [I] obtained in Example 1, diethyl diethoxy silane, diethylaluminum monoethoxide and triethylaluminum at rates of 50 mg/hr, 0.25 mmol/hr, 0.05 mmol/hr and 5 mmol/hr, respectively. Further, hydrogen and ethylene were introduced while making an adjustment so as to give a hydrogen/ethylene mol ratio of 0.45 in the vapor phase in the autoclave. At the same time, the intrasystem gases were circulated by means of the blower to maintain the total pressure at 10 kg/cm2 G. Polymerization was carried out under these conditions to give polyethylene having a bulk density of 0.36 and a melt index of 0.9. Catalytic activity was 384,000 g. polyethylene/g. Ti. The F.R. value was 7.6.

EXAMPLE 7 (a) Preparation of Solid Catalyst Component [I] 6.5 g of a commercially available anhydrous magnesium chloride, 1.5 g. of boron triethoxide and 1.5 g. of titanium tetrachloride were placed in a stainless steel pot having a content volume of 400 ml.

and containing 25 stainless steel ball each 1/2 inch in diameter, and ball-milled for 1 6 hours at room temperature in a nitrogen atmosphere, to obtain a solid catalyst component [I] containing 40 mg. of titanium per gram thereof.

(b) Polymerization Polymerization of ethylene was carried out in the same way as in Example 1 except that 10 mg.

of the solid catalyst component [I] prepared just above was used.

As a result, there was obtained 1 66 g. of a white polyethylene having a melt index of 1.3 and a bulk density of 0.30. Catalytic activity was 79,800 g. polyethylene/g. Ti hr C2H4 pressure, 3,190 g.

polyethylene/g. solid hr C2H4 pressure. The F.R. value of the polyethylene was 7.6.

EXAMPLE 8 The ball mill pot of the same type described in Example 7 was charged with 10 g. of a commercially available anhydrous magnesium chloride, 2.2 g. of magnesium diethoxide and 2.3 g. of titanium tetrachloride. The admixture was ball-milled for 1 6 hours at room temperature in a nitrogen atmosphere to obtain a solid catalyst component [I] containing 40 mg. of titanium per gram thereof.

Polymerization of ethylene was carried out in the same way as in Example 1 except that 10 mg.

of the solid catalyst component [I] prepared just above was used.

As a result, there was obtained 88.4 g. of a white polyethylene having a melt index of 0.95 and a bulk density of 0.28. Catalytic activity was 42,500 g. polyethylene/g. Ti hr. C2H4 pressure, 1 700 g.

polyethylene/g. solid hr C2H4 pressure. The F.R. value of the polyethylene was 7.6.

Claims (14)

1. A process for preparing a polyolefin, characterised by polymerizing at least one olefin by using a catalyst, said catalyst comprising the combination of: [I] a solid substance obtained by the reaction of at least the following two components: (i) a magnesium halide and (ii) a titanium compound and/or a vanadium compound; [Il] a compound represented by the general formula R'mSi(OR2)4~m wherein R' and R2 are hydrocarbon radicals having 1 to 24 carbon atoms and O~m < 3; [III] a compound represented by the general formula R3nAl(OR4)3~n wherein R3 and R4 are hydrocarbon radicals having 1 to 24 carbon atoms and 1 1~n~2; and [IV] an organometallic compound, the molar ratio of silicon in said component [II] to titanium and/or vanadium in said component [I] being in the range of 0.1 to 100, the molar ratio of aluminum in said component [III] to silicon in said component [Il] being in the range of 0.01 to 10 and the molar ratio of the metal in said component [IV] to titanium and/or vanadium in said component [I] being in the range of 0.1 to 1,000.

2. The process of claim 1 , wherein said catalyst component [I] comprises a said substance obtained by the reaction of said component (i), said component (ii) and one or more further components (cur) selected from the group consisting of compound of the general formula Me(OR)pXz~p wherein Me is an element selected from Group I through VIII in the Periodic Table, provided titanium and vanadium are excluded, R is a hydrocarbon radical having 1 to 24 carbon atoms, X is a halogen atom, z is the valence of Me and p is O < p < z.

3. The process of claim 1 , wherein said catalyst component [I] comprises a said substance obtained by the reaction of said component (i), said component (ii) and one or more further components (a) selected from the group consisting of organic halides and halogenating agents.

4. The process of claim 1, wherein said catalyst component [I] comprises a said substance obtained by the reaction of said component (i), said component (ii) and one or more further components (a) selected from the group consisting of phosphoric esters.

5. The process of claim 1, wherein said catalyst component [I] comprises a said substance obtained by the reaction of said component (i), said component (ii) and one or more further components (a) selected from the group consisting of electron donors.

6. The process of claim 1 , wherein said catalyst component (I) comprises a said substance obtained by the reaction of said component (i), said component (ii) and one or more further components (a) selected from the group consisting of polycyclic aromatic compounds.

7. The process of claim 2, wherein said component (a) represented by the general formula Me(OR)pXx~p is selected from the group consisting of Aí(OR)pX3~p, B(OR)pX3~p and Mg(OR)pX2~p.

8. The process of any one of claims 1 to 7, wherein said catalyst component (i) is supported on an oxide of a metal selected from Group II through IV in the Periodic Table.

9. The process of any one of claims 1 to 8, wherein said magnesium halide is a substantially anhydrous magnesium halide.

10. The process of any one of claims 1 to 9, wherein said titanium compound and/or vanadium compound are (or is) selected from halides, alkoxyhalides, alkoxides and halogenated oxides of titanium and/or vanadium.

11. The process of any one of claims 1 to 10, wherein said organometallic compound is an organoaluminum compound or an organoziric compound.

12. The process of any one of claims 1 to 11, wherein said olefin is an a-olefin having 2 to 12 carbon atoms.

1 3. The process of any one of claims 1 to 12, wherein the polymerization reaction is carried out at a temperature in the range of 200C to 1 200C and at a pressure in the range of atmospheric pressure to 70 kg/cm2.

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

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

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