Abstract: A process for producing an ethylene/&agr;-olefin copolymer is provided in which ethylene is copolymerized with an &agr;-olefin having three or more carbons by use of an olefin polymerization catalyst at a polymerization temperature of not lower than 120° C. The olefin polymerization catalyst comprises, as constitutional components, a) a metallocene compound comprising hafnium, b) an ionizing ionic compound, and c) an organoaluminum compound, the ionizing ionic compound (b) being a compound which is capable of changing the metallocene compound (a) into a cationic form and does not further react the cationic form of the metallocene compound.

Abstract: An ethylene/&agr;-olefin copolymer of a weight-average molecular weight of not less than 40000 is produced by copolymerization of ethylene with an &agr;-olefin having three or more carbons by use of an olefin polymerization catalyst at a polymerization temperature of not lower than 120° C., the olefin polymerization catalyst comprising, as constitutional components, a) a metallocene compound, b) an ionizing ionic compound, and c) an organoaluminum compound, the ionizing ionic compound (b) being a compound which is capable of changing the metallocene compound (a) into a cationic form and does not further react the cationic form of the metallocene compound. This process produces an ethylene/&agr;-olefin copolymer of high molecular weight in high efficiency.

Abstract: A catalyst for polymerization of an olefin, which comprises (a) a transition metal compound of the following formula (1), (2) and/or (3): ##STR1## wherein each of M.sup.1, M.sup.2 and M.sup.3 is a titanium atom, a zirconium atom or a hafnium atom, each of Cp.sup.1, Cp.sup.2, Cp.sup.3, Cp.sup.4 and Cp.sup.5 is a cyclopentadienyl group, an indenyl group, a fluorenyl group or a substitution product thereof, R.sup.1 is a hydrogen atom, a C.sub.1-20 hydrocarbon group or a C.sub.1-20 alkylsilyl group, each of X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5 and X.sup.6 is a hydrogen atom or a C.sub.1-20 hydrocarbon group, Z.sup.1 is a C.sub.1-20 hydrocarbon group, a silicon-containing C.sub.1-20 hydrocarbon group or a C.sub.1-20 alkylsilanediyl group, which serves to connect Cp.sup.3 and Cp.sup.4, Z.sup.2 is a C.sub.1-20 hydrocarbon group, a silicon-containing C.sub.1-20 hydrocarbon group or a C.sub.1-20 alkylsilanediyl group, which serves to connect Cp.sup.

Abstract: A catalyst for olefin polymerization is provided which comprises, as the components, a) a metallocene compound, b) an ionizing ionic compound, c) an organoaluminum compound, and d) a Lewis base compound. This catalyst has a stable active species and improves productivity of an olefin polymer without deterioration of the catalytic activity the metallocene is represented by General Formula (1) or (2) where Cp-containing ligands may be Cp, fluorenyl, indenyl or tetrahydroindenyl and where the metal is a group 4 metal of the periodic table.

Abstract: A catalyst for olefin polymerization is provided which comprises, as the components, a) a metallocene compound, b) an ionizing ionic compound, c) an organoaluminum compound, and d) a Lewis base compound. This catalyst has a stable active species and improves productivity of an olefin polymer without deterioration of the catalytic activity.