Abstract: A method for producing a polyolefin in the presence of a catalyst comprising a transition metal compound and an organometallic compound, wherein a catalyst system is used which comprises (A) a solid catalyst component prepared by reacting a homogeneous solution containing (I) at least one member selected from the group consisting of metal magnesium and a hydroxylated organic compound, and oxygen-containing organic compounds of magnesium, (II) at least one zirconium compound selected from the group consisting of oxygen-containing organic compounds and halogen-containing compounds of zirconium, and (III) at least one silicon compound selected from the group consisting of polysiloxanes and silanes, with (IV) at least one organoaluminum halide compound to obtain a solid product, isolating the solid product, and reacting this solid product with (V) at least one halogen-containing compound of titanium, and (B) at least one catalyst component selected from the group consisting of organoaluminum compounds.

Abstract: A method for producing a polyolefin, which comprises polymerizing or copolymerizing at least one olefin in the presence of a catalyst system comprising (A) a solid catalyst component of a titanium catalyst component obtained by reacting at least one aluminum halide compound with a homogeneous solution containing magnesium, titanium and alkoxy groups, wherein the aluminum halide compound is added to the homogeneous solution to provide a halogen atom in a mol ratio of from 0.2 to 0.4 to one mol of the alkoxy groups contained in the homogeneous solution to precipitate particles in the former step, and the aluminum halide compound is further added to provide a halogen atom in a mol ratio of from 1 to 20 to one mol of the alkoxy groups to treat the resultant mixture containing the precipitated particles in the latter step, and (B) at least one organic aluminum compound catalyst component.

Abstract: A method for producing a polyolefin in the presence of a catalyst comprising a transition metal compound and an organometallic compound, wherein a catalyst system is used which comprises: (A) a solid catalyst component prepared by reacting a uniform solution containing (I) at least one member selected from the group consisting of metal magnesium and a hydroxylated organic compound, and oxygen-containing organic compounds of magnesium, (II) an electron donative compound and (III) an oxygen-containing organic compound of titanium, with (IV) at least one aluminum halide compound to obtain a solid product, adding to this solid product (V) at least one compound selected from the group consisting of oxygen-containing organic compounds of one or more transition metals of Group IVa of the Periodic Table, and then treating the mixture with (VI) an aluminum halide compound, and (B) at least one catalyst component selected from the group consisting of organoaluminum compounds.

Abstract: This invention relates to a process for the polymerization of polyolefins, in which .alpha.-olefins are polymerized in the presence of a catalyst system composed of: the solid catalyst component (A) obtained by reacting a magnesium compound with oxygen-containing organic compounds of a transition metal, aluminum and silicon, followed by further reacting with a halogenated organoaluminum compound, and the catalyst component (B) comprising of organoaluminum compound and/or organoaluminoxane compound. The catalyst system of this invention provides polymers having an excellent particle form and the molecular weight distribution being easily controlled in a wide range, in high activity, and copolymers having a narrow composition distribution range.