Abstract: Disclosed is a catalyst for olefin polymerization comprising [I] a solid titanium catalyst component [S] comprising titanium, magnesium, halogen and an electron donor (b), which is obtained by bringing a solid adduct consisting of a magnesium compound and an electron donor (a) into contact with an electron donor (b) and a liquid titanium compound by at least one method selected from (A) a method of contacting the materials in a suspended state in the coexistence of an inert hydrocarbon solvent and (B) a method of contacting the material plural times individed portions and [II] an organometallic compound catalyst component [M] containing a metal selected from the groups I to III in the periodic table.

Abstract: Disclosed is a catalyst for olefin polymerization comprising [I] a solid titanium catalyst component [S] comprising titanium, magnesium, halogen and an electron donor (b), which is obtained by bringing a solid adduct consisting of a magnesium compound and an electron donor (a) into contact with an electron donor (b) and a liquid titanium compound by at least one method selected from (A) a method of contacting the materials in a suspended state in the coexistence of an inert hydrocarbon solvent and (B) a method of contacting the material plural times individed portions and [II] an organometallic compound catalyst component [M] containing a metal selected from the groups I to III in the periodic table. By olefin polymerization with this polymerization catalyst, an olefinic (co)polymer having high stereospecificity can be obtained with high activity.

Abstract: A process for preparing an ethylene/&agr;-olefin copolymer, which includes the steps of (A) copolymerizing ethylene and an &agr;-olefin of 3 to 20 carbon atoms by continuous vapor phase polymerization; (B) copolymerization is conducted in the presence of a prepolymerized catalyst obtained by prepolymerizing an olefin in the presence of (a) a transition metal compound, (b) an organoaluminum oxy-compound, (c) a fine particle carrier, and optionally (d) an organoaluminum compound; and (C) copolymerization is conducted under such condition that the partial pressure of sum total of ethylene and &agr;-olefin is 10 to 28 kg/cm2. The resulting ethylene/&agr;-olefin copolymer has the following properties: (i) the density is in the range of 0.880 to 0.960 g/cm3, (ii) the melt flow rate of 190° C. under a load of 2.16 kg is in the range of 0.1 to 100 g/10 min, (iii) the melt tension (MT (g)) at 190° C. and the melt flow rate (MFR (g/10 min)) satisfy the relation MT≦2.2×MFR−084.

Abstract: A process for olefin polymerization, including polymerizing or copolymerizing an olefin in the presence of an olefin polymerization catalyst composed of: a fine particle carrier; (A) a transition metal compound of a Group IVB metal of the periodic table, containing a ligand having a cyclopentadienyl skeleton; (B) an aluminoxane compound; and optionally (C) an organoaluminum compound, wherein said aluminoxane compound has an alkyl groups to aluminum ratio of 1.3 to 2.1; said transition metal compound (A) and said organoaluminum oxy-compound (B) and said organoaluminum compound being supported on the fine particle carrier; and said solid catalyst having a bulk density of 0.3 g/cm.sup.3 to 0.5 g/cm.sup.3 and a fluidity index of 45 to 70 and an olefin polymerization process using the olefin polymerization catalyst; and an olefin prepolymerized catalyst obtained by prepolymerizing the catalyst, and an olefin polymerization process using the olefin prepolymerized catalyst.

Abstract: Disclosed is an olefin polymerization catalyst comprising (A) a transition metal compound represented by the formula (I) R.sup.1 R.sup.2 MX.sub.2 (wherein M is a transition metal atom, R.sup.1 and R.sup.2 are each a cycloalkadienyl group having an aryl group and a saturated hydrocarbon group as substituents, and X is a halogen atom or the like) and (B) at least one compound selected from (b1) an organoaluminum oxy-compound, (b2) an ionized ionic compound and (b3) an organoaluminum compound. Also disclosed is a process for olefin polymerization comprising polymerizing an olefin in the presence of the above-mentioned catalyst. According to the present invention, an olefin copolymer having a crystallization temperature and a melting point both lower than those of the conventional copolymers can be prepared in the case of that the feeding amount of comonomer is smaller than those conventionally used.

Abstract: A process for preparing an olefin polymer comprising the steps of: preparing an olefin polymer ?I! by polymerizing or copolymerizing an olefin in the presence of an olefin poymerization catalyst comprising a specific solid titanium catalyst component ?A!, a specific organoaluminum compound catalyst component ?B! and a specific electron donor catalyst component ?C!; preparing an olefin polymer ?II! by polymerizing or copolymerizing an olefin in an polymerizer different from that for the polymerization of the above step in the presence of an olefin poymerization catalyst comprising a specific solid titanium catalyst component ?A!, a specific organoaluminum compound catalyst component ?B! and a specific electron donor catalyst component ?D!; and then allowing the resulting olefin polymer ?I! and the resulting olefin polymer ?II! to coexist in one polymerizer to further polymerize or copolymerize an olefin.

Abstract: A solid olefin polymerization catalyst comprising: a fine particle carrier; (A) a transition metal compound of a Group IVB metal of the periodic table, containing a ligand having a cyclopentadienyl skeleton; (B) an organoaluminum oxy-compound; and optionally (C) an organoaluminum compound, wherein said organoaluminum oxy-compound has an alkyl to aluminum ratio of 1.3 to 2.1; said transition metal compound (A) and said organoaluminum oxy-compound (B) and said organoaluminum compound being supported on the fine particle carrier; and said solid catalyst having a bulk density of 0.3 g/cm.sup.3 to 0.5 g/cm.sup.3 and a fluidity index of 45 to 70 and an olefin polymerization process using the olefin polymerization catalyst; and an olefin prepolymerized catalyst obtained by prepolymerizing the catalyst, and an olefin polymerization process using the olefin prepolymerized catalyst.