Abstract: A visbroken propylene-ethylene random copolymer and process for the manufacture thereof having the following characteristics:(a) a melting point of 115.degree. C. to 140.degree. C.;(b) an ethylene content, determined by the C.sup.13 -NMR method, of 6 to 20 mol %;(c) a block index, calculated according to the C.sup.13 -NMR method, of 1.1 or less;(d) an MFI, determined at 230.degree. C. under a load of 2.16 kg, of 015 to 100 g/10 min; and(e) a ratio of the MLMFI, determined at 230.degree. C. under a load of 10.0 kg, to the MFI, determined at 230.degree. C. under a load of 2.16 kg, of 10 to 16, the random copolymer being prepared by visbreaking, in the presence of a peroxide, a propylene-ethylene random copolymer having an MFI, determined at 230.degree. C. under a load of 2.16 kg, of 0101 to 0.3 g/10 min; and this random copolymer has a low melting point, and a film can be molded therefrom.

Abstract: A process for polymerizing or co-polymerizing propylene in the presence of a catalyst consisting essentially of (A) a solid catalyst component which is prepared by contacting(1) a copulverized material obtained by copulverizing a magnesium dihalide compound together with an acyl halide with(2) a mixture or addition-reaction product of a tetravalent titanium compound containing at least one halogen atom with at least one electron donor compound selected from the group consisting of organic compounds containing a P--O bond, organic compounds containing an Si--O bond, ether compounds, nitrite ester compounds, sulfite ester compounds, alcohol compounds, phenol compounds and naphthol compounds,(B) a trialkyl aluminum compound, and (C) a carboxylic acid ester compound.

Abstract: In the method of polymerizing .alpha.-olefins by contacting an .alpha.-olefin under polymerization conditions with a stereospecific catalyst comprising a titanium trichloride component and an organoaluminium compound, the improvement wherein said titanium trichloride component is ground during or after contact with a treating agent, said treating agent being selected from at least one ofA. an alkylene oxide, andB. a lactone.