Abstract: A method for producing a polyolefin is disclosed which comprises polymerizing an .alpha.-olefin in the presence of a catalyst composition comprising (A) a solid catalyst component prepared by contacting (a) a solid component comprising a magnesium alkoxide and/or a magnesium salt of a fatty acid supported on an inorganic oxide composed of at least one member selected from the group consisting of oxides of elements belonging to Groups II, III and IV of the periodic table and/or a composite inorganic oxide containing at least one member selected from the group consisting of oxides of elements belonging to Groups II, III and IV of the periodic table, the inorganic oxide or composite inorganic oxide having a surface hydroxide concentration of 3 .mu.mol/m.sup.2 or less, (b) an electron donating compound and (c) a titanium halide, (B) an organic metal compound, and (C) an electron donating compound.

Abstract: The present invention relates to a propylene polymer composition comprising:65 to 95% by weight of a propylene homopolymer having (a) an intrinsic viscosity ([.eta..sub.1 ]) of 0.5 to 3.5 dl/g, (b) a xylene soluble content at ordinary temperature (Xs) of not more than 3% by weight, and a difference (.DELTA.[.eta..sub.1 ]) between ([.eta..sub.1 ]) of xylene insoluble portion at the ordinary temperature and ([.eta..sub.1 ]) of xylene soluble portion at the ordinary temperature of not more than 0.5 dl/g, (c) an isotactic pentad fraction (IP) falling within the range represented by the following equation:IP.gtoreq.-0.624[.eta..sub.1 ]+97.5,and (d) a crystallization temperature (Tc) falling within the range represented by the following equation:Tc.gtoreq.-2.33[.eta..sub.1 ]+116.0;and5 to 35% by weight of a propylene-ethylene random copolymer having (e) an intrinsic viscosity ([.eta..sub.2 ]) of less than 2.8 dl/g and (f) an ethylene content of 10 to 35% by weight.

Abstract: The present invention relates to a propylene polymer composition comprising:60 to 94% by weight of a propylene homopolymer having (a) an intrinsic viscosity ([.eta..sub.1 ]) of 0.5 to 5 dl/g, (b) a xylene soluble content at ordinary temperature (Xs) of not more than 3% by weight, and a difference (.DELTA.[.eta..sub.1 ]) between ([.eta..sub.1 ]) of xylene insoluble portion at the ordinary temperature and ([.eta..sub.1 ]) of xylene soluble portion at the ordinary temperature of not more than 0.5 dl/g, (c) an isotactic pentad fraction (IP) falling within the range represented by the following equation:IP.gtoreq.-0.624[.eta..sub.1 ]+97.5,and (d) a crystallization temperature (Tc) falling within the range represented by the following equation:Tc.gtoreq.-2.33[.eta..sub.1 ]+116.0; and6 to 40% by weight of a propylene-ethylene random copolymer having (e) an intrinsic viscosity ([.eta..sub.2 ]) of not less than 2.8 dl/g and (f) an ethylene content of 30 to 80% by weight.

Abstract: A propylene polymer composition having excellent whitening resistance, impact resistance, rigidity and flowability.The propylene polymer composition comprises (A) 100 parts by weight of a propylene polymer or a modified polymer obtained by heat-treating the propylene polymer in an organic peroxides and (B) 0.1 to 1.5 parts by weight of an ester of an aliphatic saturated monocarboxylic acid and a polyhydric alcohol, and the propylene polymer essentially consists of two particular polymer fractions or three particular polymer fractions polymerized over stereoregular catalysts and combinationed in a specific ratio.

Abstract: The propylene-ethylene block copolymer composition of the invention is excellent in transparency as well as in stiffness and low temperature impact strength.The copolymer composition of the present invention comprises (a) from 0.01 to 1.0 part by weight of a nucleating agent and (b) from 0.01 to 3.0 parts by weight of talc having an average particle size of not more than 10 microns, admixed in 100 parts by weight of propylene-ethylene block copolymer. Said propylene-ethylene block copolymer was formed in a multi-stage polymerization process wherein the ethylene content of the copolymer formed at the propylene-ethylene copolymerization stage is from 5 to 40% by weight based on the total polymerization amount of the copolymer formed at said propylene-ethylene copolymerization stage.

Abstract: A process for producing a propylene block copolymer by a three-step reaction in the presence of a stereoregular catalyst. At the first step, propylene is polymerized at a temperature of 55.degree. C. or more to form polypropylene having an intrinsic viscosity of from 0.5 to 3.5 in the prescribed amount. At the second step, propylene is polymerized at a temperature of from 30.degree. to 90.degree. C. to form polypropylene having an intrinsic viscosity of at least 4 in the prescribed amount. And at the third step, ethylene and propylene are copolymerized at a temperature of from 30.degree. to 90.degree. C. to form an ethylene-propylene copolymer having an intrinsic viscosity of at least three in the prescribed amount. The propylene block copolymer formed by the three steps is superior and well balanced in impact resistance and stiffness.