Abstract: Acetylene and other 1-alkynes are polymerized by a catalyst system comprised of a transition metal complex consisting of at least one binucleating ligand attached to at least one transition metal containing nucleus; and at least one organometallic cocatalyst containing at least one element of Group 1a, 2a or Group 3a.

Abstract: Supported Ti.sup.III catalysts are prepared by contacting a slurry of a solid inorganic support such as magnesium chloride in a hydrocarbon medium such as Isopar.RTM. E containing a tetravalent titanium compound containing at least two halogen atoms such as titanium tetrachloride with hydroquinone or a substituted hydroquinone.

Abstract: A process for the preparation of polyisoprene by polymerizing isoprene in the presence of a beta-TiCl.sub.3 containing catalyst is disclosed thereby an activator is prepared by reacting a hydrocarbylaluminum compound and a hydroxy-aromatic compound, having at both ortho-places with respect to the hydroxy-group a secondary or tertiary alkyl-group.

Abstract: EPDM rubbers having improved properties are obtained by carrying out the polymerization using a catalyst system consisting of a vanadium compound, an aluminum halide and an ester, the ester being a polymer containing ester groups.

Abstract: An olefin polymerization catalyst prepared by reacting a metal dihalide and a transition metal, then reacting that component with a precipitating agent, and then reacting the resulting solid with an activating component, wherein multiple activation steps are used so that it is possible to obtain a given level of activity with less activating component.

Abstract: An olefin polymerization catalyst prepared by reacting an admixture of anhydrous magnesium dihalide and hydrous magnesium dihalide with reactants including benzoic acid ester, an alkoxytitanium compound, an organoaluminum halide, and a titanium halide.

Abstract: A vanadium-containing catalyst component useful for the polymerization of olefins to polyolefins having a high molecular weight and a broad molecular weight distribution comprising polymerizing the polyolefins in the presence of a catalyst comprising (A) a vanadium-containing catalyst component obtained by contacting an inert support material with a dihydrocarbyl magnesium compound, optionally an oxygen-containing compound, a vanadium compound, a Group III metal halide, and (B) an aluminum alkyl cocatalyst.

Abstract: A vanadium-containing catalyst component useful for the polymerization of olefins to polyolefins having a high molecular weight and a broad molecular weight distribution comprising polymerizing the polyolefins in the presence of a catalyst comprising (A) a vanadium-containing catalyst component obtained by contacting an inert support material with a dihydrocarbyl magnesium compound, optionally an oxygen-containing compound, a vanadium compound, a Group III metal halide, and (B) an aluminum alkyl cocatalyst.

Abstract: Olefins are polymerized in the presence of catalysts prepared from titanium compounds prepared by reacting a titanium compound such as titanium tetraisopropoxide with a compound containing at least one aliphatic hydroxyl group.

Abstract: A process for producing a novel-highly active lanthanide containing catalysts comprising products formed by reacting a lanthanide halide, and an electron doner ligand with an organometal cocatalyst component and its use in the polymerization of olefins, especially olefins such as ethylene, 1,3-butadiene, isoprene and the like. In one embodiment, an organic base is used to increase catalyst activity in those instances where rare earth metal halide-ligand complex is formed with a ligand containing an acidic proton. In another embodiment, diolefins and vinyl aromatics are polymerized in a two-stage process employing a lanthanide complex-organometal cocatalyst in the first stage and a free radical initiator in the second stage.

Abstract: A catalyst composition for use in polymerizing alpha olefins which comprises a solid supported titanium complex and a cocatalyst comprising a mixture of an alkyl aluminum halide and a dialkyl magnesium or alkyl lithium compound.

Abstract: A catalyst component for polymerization of .alpha.-olefins is produced by causing mutual contact of:(A) a magnesium halide containing solid;(B) an electron donating compound, having the structural site as represented by the formula show below in its molecule: ##STR1## and (C) a titanium halide. The catalyst thus produced has high polymerization activity and is capable of producing polymers having excellent stereoregularity.

Abstract: In a polymerization of alpha mono-olefins by means of certain supported coordination catalysts systems which comprise (a) a procatalyst, (b) a cocatalyst, and (c) a selectivity control agent, wherein (a) is a highly active solid composition which comprises magnesium chloride, titanium tetrachloride and an electron donor; and (b) is an aluminum trialkyl; the selectivity control agent comprises a strong selectivity control agent and a weak selectivity control agent.

Abstract: Polypropylene fibers having a much improved percentage heat shrinkage and also an improved tenacity are provided, which fibers comprise a polypropylene resin having a density of 0.905 or more, an isotactic pentad ratio of boiling n-heptane-insoluble portion (P.sub.0) of 0.960 or more and a ratio of pentad having two different kinds of configurations (P.sub.2), of 0.002 (0.2%) or less.

Abstract: A vanadium dichloride-ether complex is carried on a porous support. This complex can be produced by either forming VCl.sub.2 and thereafter complexing the material with an ether or forming an ether complex with VCl.sub.4 or VCl.sub.3 and thereafter reducing the vanadium compound to VCl.sub.2. It is also possible to carry out the complexing reaction and the reduction essentially simultaneously. The resulting catalyst in combination with a cocatalyst is capable of giving high activity in olefin polymerization and demonstrates good sensitivity to molecular weight control agents, thus allowing the production of a broad spectrum of polymers so far as molecular weight is concerned.

Abstract: Ethylene and alpha-olefins are homopolymerized or copolymerized with another olefin monomer in the presence of a catalyst system comprising an organo metal cocatalyst and titanium-containing catalyst component, said titanium-containing catalyst component being obtained by reacting together a porous particulate material, an organic magnesium compound, optionally an oxygen containing compound, titanium tetrachloride and a Group IIIa metal hydrocarbyl dihalide.

Abstract: A method of producing a polymerization catalyst component suitable for use in the polymerization of alpha-olefins, which method comprises forming an active component by co-comminuting an inorganic Lewis acid, a first organic electron donor, a support base selected from the group consisting of the Group IIA and IIIA salts and the salts of the multivalent metals of the first transition series with the exception of copper, and a polymerization active tri-, tetra-, or penta- valent transition metal compound of a Group IVB-VIB metal, and heating the active component in an inert hydrocarbon solvent to produce the polymerization catalyst component. The active component can be heated in the inert hydrocarbon solvent in the presence of an additional polymerization active tri-, tetra-, or penta- valent transition metal compound of a group IVB-VIB metal. In addition, a second organic electron donor may be incorporated in the active component.

Abstract: Novel titanium compounds or complexes are prepared by reacting a titanium compound such as titanium tetraisopropoxide with a mixture comprising (a) at least one compound containing at least one aromatic hydroxyl group and (b) at least one compound having at least one aliphatic hydroxyl group. These compounds and/or complexes are useful as the transition metal component in Ziegler-Natta catalysts.

Abstract: Olefins are polymerized in the presence of catalysts prepared from titanium compounds prepared by reacting a titanium compound such as titanium tetraisopropoxide with a compound containing at least one aliphatic hydroxyl group.

Abstract: Isotactic index improvement is achieved for C.sub.3 and higher alpha olefins in systems containing a catalyst component comprising titanium supported on a magnesium halide support. The titanium component is formed by copulverizing the magnesium halide with one or more electron donors followed by treatment with liquid titanium halide. The improvement is achieved by using a dialkylaluminoxane component with the trialkylaluminum co-catalyst normally used. In slurry polymerizations, the isotactic index of the polymer has been improved.

Abstract: A free-flowing, high activity propylene polymer procatalyst component is prepared by the addition of limited amounts of a mineral oil (e.g., 5 to 25 percent) to the recovered MgCl.sub.2 /TiCl.sub.4 /ED procatalyst. The mineral oil becomes absorbed into the catalyst pores resulting in dry, free-flowing powders which retain their original activity for more than two months. This method of catalyst storage and shipping may prove more convenient than the previously used mineral oil slurries. Further, this technique of introducing suitable inert liquids into the catalyst pores results in substantial improvement in catalyst performance.

Abstract: A process for producing a novel-highly active lanthanide containing catalyst comprising the product formed by admixing a lanthanide hydroxyhalide and an electron donor bidentate organic ligand chosen from among diamines, dihydric alcohols, and diketones with an organoaluminum cocatalyst component and its use in the polymerization of olefins, especially olefins such as ethylene and 1,3-butadiene.

Abstract: A titanium trichloride catalyst component containing a minor amount of prepolymerized alpha-olefin and useful in the polymerization of alpha-olefins is produced by reducing titanium tetrachloride with an organoaluminum compound at low temperatures and then treating the resulting reduced solids product with about 1 to 1,000 wt. % alpha-olefin so as to obtain a prepolymerized titanium trichloride reduced solid. The prepolymerized reduced solid can thereafter be activate to a highly active prepolymerized titanium trichloride by treating the prepolymerized reduced solid with a halogenated hydrocarbon and a Lewis base complexing agent or titanium tetrachloride and a Lewis base complexing agent. The prepolymerized reduced solid and the prepolymerized activated titanium trichloride manifests substantially no evidence of friability upon being subjected to mechanical shearing forces.

Abstract: An intermetallic compound comprising the reaction product of a transition metal and a reducing metal of a higher oxidation potential than the transition metal obtained by the reaction of a polymeric transition metal oxide alkoxide and the reducing metal in the presence of dicarbonyl compound; and catalyst components and systems for the polymerization of alpha olefins.

Abstract: A supported type catalyst component for .alpha.-olefin polymerization, having a higher activity and capable of affording a highly stereoregular polymer is provided, which component comprises a solid product (II) obtained by reacting Mg compound(s) of formula MgR.sup.1 R.sup.2 (wherein R.sup.1 is alkyl, aryl, alkoxy or aryloxy and R.sup.2, alkyl, aryl, alkoxy, aryloxy or halogen), with a complex of compound(s) selected from Al halides and Al compounds of formula AlR.sub.n.sup.3 X.sub.3-n (wherein R.sub.3 is alkyl, aryl, alkoxy or aryloxy; X, halogen; 0.ltoreq.n<2) with an organic acid ester; and reacting the resulting solid product (I) (a carrier) with a liquid halogen-containing Ti compound. Preactivation of the solid product (II) with an organoaluminum compound and an .alpha.-olefin affords a catalyst component superior in storage stability and polymerization reproducibility.

Abstract: A catalyst system for the polymerization of olefins which comprises;(A) a hydrocarbyloxy group-containing solid catalyst component prepared by (i) reducing a titanium compound represented by the general formula Ti(OR.sup.1).sub.n X.sub.4-n wherein, R.sup.1 represents a hydrocarbon radical of 1-20 carbon atoms, X represents a halogen atom, and n represents a number satisfying 0<n.ltoreq.4, with an organoaluminum compound represented by the general formula AlR.sup.2.sub.m Y.sub.3-m wherein, R.sup.2 represents a hydrocarbon radical of 1-20 carbon atoms, Y represents a halogen atom, and m represents a number satisfying 1.ltoreq.m.ltoreq.3, and (ii) treating the resulting, hydrocarbon solvent-insoluble, hydrocarbyloxy group-containing solid product in a slurry state with an ether compound and titanium tetrachloride at a temperature of 30.degree.-120.degree. C., and(B) an organoaluminum compound.

Abstract: A process for producing .alpha.-olefin polymers having high crystallinity and good particle form, with a high yield is provided. The polymerization therefor is carried out in the presence of a preactivated catalyst suitable particularly to gas phase polymerization or gas phase polymerization following slurry or bulk polymerization.The catalyst is prepared by reacting a reduction solid prepared by reducing TiCl.sub.4 with an organoaluminum compound, with an electron donor and an electron acceptor to obtain a solid product, andcombining this solid product with an organoaluminum compound, an .alpha.-olefin and a reaction product of an organoaluminum compound with an electron donor.

Abstract: An improved method for the preparation of homopolymers and copolymers of alpha olefins by means of a catalyst system comprising a titanium halide, an aluminum alkyl, and a phenolic compound which has a tendency to crystallize at low temperatures in the reactor feed system is disclosed. The improvement comprises prereacting a portion of the aluminum alkyl with the phenolic compound such that the components remain catalytically inactive and then activating the catalyst by adding the remainder of the aluminum alkyl to prereacted components in situ in the polymerization reactor, thereby preventing the crystallization of the phenolic compound at low temperatures in the feed system for the reactor.

Abstract: Olefins are polymerized in the presence of catalysts prepared from titanium compounds prepared by reacting a titanium compound such as titanium tetraisopropoxide with a compound containing at least one aliphatic hydroxyl group.

Abstract: Olefins are polymerized in the presence of, as a catalyst therefor, the catalytic reaction product resulting from admixing(A) at least one hydrocarbon soluble organomagnesium material;(B) at least one organic hydroxyl-containing material;(C) at least one reducing halide source; and(D) at least one transition metal (Tm) compound.

Abstract: A process for the preparation of homopolymers and copolymers of .alpha.-monoolefins by means of a Ziegler-Natta catalyst system comprising (1) a halide of trivalent titanium, (2) an oxygen compound (ester) having a specific formula and (3) an aluminum-alkyl, the titanium halide (1) and the oxygen compound (2) being milled together before use, wherein the catalyst system employed contains, as a further component, (4) a phenolic compound of the formula ##STR1## where R.sup.3 is C.sub.1 -C.sub.6 -alkyl, R.sup.4 is hydrogen or C.sub.1 -C.sub.6 -alkyl, p is an integer from 0 to 5 and q is an integer from 1 to 5.

Abstract: A new process is described for polymerizing and copolymerizing conjugate diolefins characterized by the use of a catalytic system comprising at least one compound of Group III B of the periodic system, at least one non-halogenated aluminium alkyl, at least one compound containing one or more hydroxyls of acid or neutral type, and possibly an inorganic compound containing Cl or Br in ionizable form or an organic halogen derivative.The new process allows the preparation, both in the absence and in the presence of an inert diluent, of polydiolefins of essentially entirely 1,4-cis structure which even in the absence of a purification stage contain a very small quantity of catalytic residues.

Abstract: A catalyst composition for the polymerization or copolymerization of olefins composed of(A) a titanium component (a-1) or (a-2),(a-1) a highly active titanium component containing titanium, magnesium and halogen as essential ingredients, or(a-2) a highly active titanium catalyst component obtained by treating component (a-1) with an organic compound containing active hydrogen bonded to oxygen, and(B) an organoaluminum compound component, wherein(i) when component (A) is the component (a-1), component (b) is an organoaluminum compound component obtained by treating a halogen-containing organoaluminum compound having a halogen/Al atomic ratio of at least 1 but less than 2 with a compound selected from the group consisting of water and organic compounds having active hydrogen bonded to oxygen, and(ii) when component (A) is the component (a-2), the component (B) is a halogen-containing organoaluminum compound having a halogen/Al atomic ratio of at least 1 but less than 2, and the ratio of the amount (x) of the or

Abstract: A Ziegler type supported catalytic component for polymerization of an .alpha.-olefin is prepared by allowing an organo-magnesium compound expressed by a generic formula of R'MgX' (wherein R' represents a hydrocarbon group having 1 to 20 carbon atoms and X' either a halogen atom chosen out of chlorine, bromine and iodine or a hydrocarbon group having 1 to 20 carbon atoms) to react with carbon tetrahalide in the presence of an electron donor compound to obtain a solid product through a solid-liquid separation process; by heat treating the separated solid product with a carbon halide; by treating the heat treated solid product with phenols at 90.degree. to 180.degree. C.; and by treating this phenol treated product further with a halogenated titanium compound. Homo- or co-polymerization of an .alpha.-olefin is carried out in the presence of a catalyst composition consisting of the above catalytic component and an organo-aluminum compound. With this catalytic component, stereospecific polymerization of an .alpha.

Abstract: Olefins are polymerized in the presence of a catalyst containing novel titanium compounds or complexes which are prepared by reacting a titanium compound such as titanium tetraisopropoxide with a compound containing at least one aromatic hydroxyl group.

Abstract: A aliphatic hydrocarbon soluble mixed aluminum hydrocarbyl-Lewis base co-catalyst composition comprising (i) at least two different classes of aluminum hydrocarbyls the first being an aluminum hydrocarbyl halide, the second being an aluminum hydrocarbyl hydride and/or aluminum trialkyl and (ii) at least one Lewis base represented by the formula: ##STR1## wherein each Y can be -OR', -NR.sub.2 ' and R' with the proviso that at least two be -OR' or -NR.sub.2 ', Z is an alkylene radical forming a 5 or 6 membered ring with the carbonyldioxy group or Z is alkyl substituted alkylene group wherein the alkyl radical can have from 1 to 8 carbon atoms, R is an aryl, allyl or alkyl group having 1 to 20 carbon atoms and R' is an alkyl, cycloalkyl, aryl or aralkyl radical having from 1 to 20 carbon atoms.The co-catalyst is employed with a titanium halide catalyst for the polymerization of olefins to obtain a advantageous balance of catalytic activity and polymer product stereoregularity.

Abstract: Provided is a process for preparing a polyolefin, characterized by polymerizing at least one .alpha.-olefin in the presence of a catalyst which comprises the combination of:[I] a solid catalyst component comprising a solid substance obtained by contacting the following components (1) through (3) with one another and (4) a titanium compound supported on said solid substance:(1) a magnesium halide,(2) a compound represented by the general formula ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen, or a halogen atom, R.sup.4 is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1.ltoreq.n.ltoreq.30, and(3) at least one compound selected from the group consisting of:(a) compounds represented by the general formula ##STR2## wherein R is hydrogen, a halogen atom, or a hydrocarbon radical having 1 to 24 carbon atoms, and r, p and q are integers satisfying the following conditions:1.ltoreq.r.ltoreq.3, 0.ltoreq.p<6, 0.ltoreq.

Abstract: Diene polymers having a high content of cis-1,4 addition are prepared by polymerizing a 1,3-diene monomer in a hydrocarbon solvent in the presence of a catalyst composition comprising (a) a carboxylated metal oxy aluminate compound in which the metal is nickel or cobalt, (b) an organometallic compound of a metal of Groups I, II, and III of the Periodic System, and (c) one or more fluorine containing compounds selected from the group consisting of boron trifluoride complexes with ethers, alcohols or mixtures thereof; hydrogen fluoride; hydrogen fluoride complexes with ethers, alcohols, or mixtures thereof and mixtures of said compounds.The resultant polymers exhibit good green strength and tack and are particularly suitable for use as tire rubbers.

Abstract: A polypropylene resin from which high-rigidity molded products can be produced even when no particular additive is added, is provided, which resin has a melt rate of 0.1 to 100, a density of 0.905 to 0.936, and a boiling n-heptane-insoluble part whose isotactic pentad ratio (P.sub.o) is 0.975 to 0.995, and whose pentad ratio (P.sub.2) having two different kinds of configurations of 0.002 to 0.000%, and preferably has a melting point of 165.degree. to 170.degree. C. as measured by differential scanning calorimetry.

Abstract: The present invention relates to catalysts which can be used for the polymerization and copolymerization of propylene with other alpha-olefins, characterized in that they comprise a support containing essentially magnesium chloride and possibly a chlorinated aluminium derivative, and occurring in the form of spheroidal particles having a mean diameter by mass comprised between 10 and 100 microns and a particle size distribution such that the ratio of the mean diameter by mass to the mean diameter by number is less than or equal to 3, which support has been treated by an electron donor compound chosen from among the aromatic ethers and aromatic acid esters and which when impregnated with titanium tetrachloride comprises 0.5 to 3% of atoms of titanium per atom of magnesium, and process for utilizing the said catalyst.

Abstract: An ethylene polymerization catalyst comprising a supported precursor of vanadium trihalide/electron donor complex and alkylaluminum or boron halides, when combined with alkylaluminum cocatalyst and alkyl halide promoter provides enhanced polymerization and productivity plus superior polyethylene.

Abstract: A process of preparing a bimodal or multimodal homopolymer of a conjugated diene or a bimodal or multimodal copolymer of a conjugated diene with another conjugated diene or with a vinyl aromatic compound consists in polymerizing the monomer(s) in a reaction medium at a temperature of between 20.degree. C. and 200.degree. C. in the presence of a catalyst system formed of the reaction product of:(a) an organic compound of a metal of group 3A of the periodic classification of elements of the Mendeleev Table having one of the following formulas;M.sup.1 M.sup.3 R.sup.1 R.sup.2 R.sup.3 R.sup.4M.sup.2 (M.sup.3 R.sup.1 R.sup.2 R.sup.3 R.sup.4).sub.2M.sup.3 R.sup.1 R.sup.2 R.sup.3M.sup.1 OM.sup.3 R.sup.1 R.sup.2with (b) at least one electron-donor compound containing at least one heteroatom,and adding to the reaction medium during the course of the polymerization reaction a compound of a transition metal of groups 1b to 7B and 8 or a magnesium compound of the general formula Mg(A).sub.2.

Abstract: A process for producing an olefin copolymer rubber containing 25 to 75% by weight of propylene, which comprises polymerizing ethylene and propylene, or ethylene, propylene and at least one nonconjugated diene, in solution in the presence of a catalyst, said catalyst being composed of (A) a Ti-containing solid component precipitated from a liquid product obtained by reacting a titanium tetrahalide with an organomagnesium compound in a halogenated hydrocarbon solvent in the presence of an ether represented by the general formula R.sup.1 OR.sup.2 wherein R.sup.1 and R.sup.2 are identical or different and each represents a hydrocarbon group having 2 to 12 carbon atoms, and (B) an organoaluminum compound.

Abstract: A catalyst system for the polymerization of olefins comprising:(A) a solid catalyst component containing hydrocarbyloxy groups obtained by reacting a titanium compound represented by the general formula Ti(OR.sup.1).sub.n X.sub.3-n (wherein R.sup.1 is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and n is a number defined by 0<n.ltoreq.3) with an ether compound and titanium tetrachloride in a slurry state in the presence of a magnesium halide, and(B) an organoaluminum compound.

Abstract: A superior high-rigidity and high-melt-viscoelasticity polypropylene for sheets to be post-processed and for blow molding is provided which polypropylene is produced by subjecting propylene to a multi-stage polymerization into polymer portions of two sections in the presence of a specified Ziegler Natta catalyst, the relationship between the intrinsic viscosities of the polymer portions of the respective sections being regulated within a specified range and also the amount ratio of the polymer portions of the respective sections being regulated.

Abstract: Disclosed is an improved method of making a cellular crosslinked polymer with a metathesis-catalyst system where a metathesis-catalyst is activated with an alkylaluminum iodide compound.In a preferred embodiment, two parts of the metathesis-catalyst system form the basis for two solutions, a catalyst/monomer solution and an alkylaluminum iodide activator/monomer solution. At least one solution also contains a blowing agent. The solutions are combined in one place, such as the mixing head of a reaction injection molding machine, and then injected into another place, such as a mold, where the monomer reacts to form a cellular crosslinked polymer.

Abstract: An improved Ziegler/Natta catalyst for the polymerization of .alpha.-olefins containing from 2 to 30 carbon atoms, comprising titanium halide and organoaluminum cocatalyst modified by addition of ketones and monoethers. Metal halides can be used to further modify the catalyst.

Abstract: Incorporation of an ester plasticizer having a solubility parameter from about 7.8 to about 10.2 (cal/cc).sup.1/2 increases the flexibility and impact strength of poly(dicyclopentadiene). In a preferred embodiment of the method for poly(dicyclopentadiene) synthesis, the plasticizer is incorporated into at least one of two parts of a metathesis-catalyst system: a catalyst/monomer solution or an activator/monomer solution. The two parts are then combined in the mixing head of a reaction injection molding machine and injected into a mold where the reaction mixture rapidly sets up into a thermoset polymer with greater flexibility and impact strength than is found in the corresponding unplasticized poly(dicyclopentadiene).

Abstract: A process for producing .alpha.-olefin polymers of a high stereoregularity which comprises homopolymerizing an .alpha.-olefin having 3 to 10 carbon atoms or copolymerizing said .alpha.-olefin with other olefins of the same group or with ethylene using a catalyst system comprising three components (A), (B) and (C):(A) a solid catalyst produced by reaction among a solid product described below, a compound group (III) comprising at least one compound having an O--C.dbd.O linkage and at least one compound having at least one member selected from C--O--H, C--O--C, C--N, C.tbd.N, N--O--C, P--O--C, P--N--C, C--S--H, C--S--C, S--O--C and P--S--C linkages, and a titanium compound having at least one titanium-halogen linkage, said solid product being prduced by reacting an organo-magnesium compound with at least one of the following halogen-containing compounds (I) and (II),(I) a halogeno-silicon compound of the formula, R.sub.n SiX.sub.

Abstract: A process for producing a polyolefin, which comprises polymerizing an olefin in the presence of a catalyst system comprising:(a) a solid catalyst component obtained by supporting a titanium compound and/or a vanadium compound on a solid product derived from the reaction of a phenol, an aromatic carboxylate ester, and a solid reaction product of an organomagnesium compound and an aryloxyaluminum compound represented by the general formula Al(OR.sup.1).sub.3, wherein R.sup.1 represents an aryl group having 6 to 20 carbon atoms; and(b) an organoaluminum compound.