Abstract: A solid catalyst component for olefin polymerization comprising a hydrocarbon-insoluble product(III) obtained by reacting(A) a silicon compound selected from the group consisting of(1) silicon compounds represented by the general formula R.sup.1.sub.a R.sup.2.sub.b R.sup.3.sub.c Si, wherein R.sup.1, R.sup.2 and R.sup.3 are each an alkyl, cycloalkyl, aralkyl, aryl, alkoxy, aryloxy, or hydroxyl group or a halogen or hydrogen atom; and a, b and c are numbers defined by the formulas 0.ltoreq.a,b,c,.ltoreq.

Abstract: A solid catalyst component for olefin polymerization comprising a hydrocarbon-insoluble product (III) obtained by reacting(A) a silicon compound selected from the group consisting of(1) halogen-containing silicon compounds,(2) silicon compounds having a monomeric unit ##STR1## (wherein R.sup.1 and R.sup.2 may be the same or different, R.sup.1 represents an alkyl, aryl, cycloalkyl, alkoxy, or aryloxy group, or a hydrogen atom, and R.sup.2 represents an alkyl, aryl, or cycloalkyl group or a hydrogen or halogen atom) and a polymerization degree of 2 to 10,000,(3) silanols of the general formula R.sub.l.sup.3 Si(OH).sub.4-l (wherein R.sup.3 represents an alkyl, aryl, or cycloalkyl group or a hydrogen atom, and l is 1, 2 or 3) or condensation products thereof,(4) silicon compounds represented by the general formula R.sub.m.sup.4 Si(OR.sup.5).sub.4-m (wherein R.sup.4 represents n alkyl, aryl, cycloalkyl, or alkenyl group or a hydrogen atom, R.sup.

Abstract: In a slurry polymerization for producing an ethylene homopolymer or ethylene-.alpha.-olefin copolymer in multiple stages, in which the gas phase hydrogen concentration in each stage is different, using a catalyst system comprising a transition metal compound component and an organoaluminum compound component, the improvement which comprises conducting the polymerization by the use of a solid catalyst component comprising a titanium compound and/or vanadium compound supported on a specified magnesium compound, as the transition metal compound component, in a molar ratio of gas phase hydrogen to ethylene of 0.5 to 15 in the first stage thereby obtaining 30 to 95% by weight, of the total polymer, and in the second stage in a molar ratio of gas phase hydrogen to ethylene, not exceeding 0.2. By this process, it is possible to produce polyethylene having high melt flow and good homogeneity to give molded articles having fewer fish-eyes and less unevenness.

Abstract: A process for producing olefin polymers, which comprises polymerizing or copolymerizing olefins in the presence of a catalyst comprising a solid catalyst component and an organoaluminum compound, said solid catalyst component being a titanium compound and/or a vanadium compound supported on a solid product obtained by the reaction between a Grignard compound and a boron compound represented by the general formula B(OR.sup.1).sub.a R.sup.2.sub.b R.sup.3.sub.c, wherein a, b and c are numbers defined by the formulas 0<a.ltoreq.3, 0.ltoreq.b<3, 0.ltoreq.c<3 and a+b+c=3, R.sup.1 represents a hydrocarbon radical having 1 to 20 carbon atoms, and R.sup.2 and R.sup.3, which may be the same or different, represent each a hydrogen atom, a hydrocarbon radical having 1 to 20 carbon atoms, or a halogen atom.

Abstract: A catalyst system prepared by mixing components (A), (B) and (C):(A) a solid titanium component prepared from an organo-magnesium compound, a silicon halide compound and/or an aluminum halide compound, an electron donor and TiCl.sub.4,(B) an organoaluminum activator, and(C) an electron donor.

Abstract: .alpha.-Olefin polymers of high stereoregularity are prepared by polymerizing the .alpha.-olefin with a catalyst prepared by mixing components (A), (B) and (C):(A) a solid titanium component prepared from an organo-magnesium compound, a silicon halide compound and/or an aluminum halide compound, an electron donor and TiCl.sub.4,(B) an organoaluminum activator, and(C) an electron donor.