The present invention is directed to a polypropylene composition (C) applicable for the production of pressure pipes, said composition comprising a propylene random copolymer (rPP) and an impact modifier being a polyethylene (PE), as well as an article comprising said composition.

The present invention is directed to a polypropylene composition (C) applicable for the production of pressure pipes, said composition comprising a propylene random copolymer (rPP) and an impact modifier being a polyethylene (PE), as well as an article comprising said composition.

Catalyst systems containing a titanium alkoxymagnesium halide supported catalyst component can be used for the polymerization of olefins. The catalyst can be prepared from a microcrystalline solid alkoxymagnesium halide support having a lattice spacing in the 5 nm to 15 nm range.

Catalyst systems containing a titanium alkoxymagnesium halide supported catalyst component can be used for the polymerization of olefins. The catalyst can be prepared from a microcrystalline solid alkoxymagnesium halide support having a lattice spacing in the 5 nm to 15 nm range.

An ethylene-propylene block copolymer resin is provided that is suitable as an insulation layer of an electric power cable. The ethylene-propylene block copolymer is obtained by polymerization of a propylene homopolymer or an ethylene-propylene random copolymer with an ethylene-propylene rubber copolymer in stages in reactors in the presence of a Ziegler-Natta catalyst obtained using two internal electron donors, wherein one of the two internal electron donors is a compound comprising an ester group and an alkoxy group, the ethylene-propylene block copolymer has a melting temperature of 150 to 160 C., the content of the solvent extract thereof when extracted at room temperature with xylene is 30 to 50% by weight, and the intrinsic viscosity of the solvent extract is 1.5 to 3.0 dl/g.

An ethylene-propylene block copolymer resin is provided that is suitable as an insulation layer of an electric power cable. The ethylene-propylene block copolymer is obtained by polymerization of a propylene homopolymer or an ethylene-propylene random copolymer with an ethylene-propylene rubber copolymer in stages in reactors in the presence of a Ziegler-Natta catalyst obtained using two internal electron donors, wherein one of the two internal electron donors is a compound comprising an ester group and an alkoxy group, the ethylene-propylene block copolymer has a melting temperature of 150 to 160 C., the content of the solvent extract thereof when extracted at room temperature with xylene is 30 to 50% by weight, and the intrinsic viscosity of the solvent extract is 1.5 to 3.0 dl/g.

A catalyst for polymerization of an olefin is disclosed, including a compound represented by the general formula R.sup.1R.sup.2Si(NHR.sup.3).sub.2 wherein R.sup.1 is a cycloalkyl group having 3 to 12 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms; R.sup.2 is a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms; the number of carbon atoms of R.sup.1 is larger by 2 or more than that of R.sup.2; and R.sup.3 is a linear alkyl group having 2 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cycloalkyl group having 3 to 6 carbon atoms, as an external electron-donating compound. The catalyst can prepare a polymer having excellent hydrogen activity and high stereoregularity and melt flow rate even in homopolymerization at a high temperature, with high productivity.

A catalyst for polymerization of an olefin is disclosed, including a compound represented by the general formula R.sup.1R.sup.2Si(NHR.sup.3).sub.2 wherein R.sup.1 is a cycloalkyl group having 3 to 12 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms; R.sup.2 is a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms; the number of carbon atoms of R.sup.1 is larger by 2 or more than that of R.sup.2; and R.sup.3 is a linear alkyl group having 2 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or a cycloalkyl group having 3 to 6 carbon atoms, as an external electron-donating compound. The catalyst can prepare a polymer having excellent hydrogen activity and high stereoregularity and melt flow rate even in homopolymerization at a high temperature, with high productivity.

A Ziegler-Natta catalyst composition is disclosed. The catalyst composition includes an internal electron donor with improved polymerization kinetics, a long lifetime, improved stereoselectivity and/or improved hydrogen response.

The magnesium alkoxide particle contains the reaction product of the following components: 1) a magnesium powder; 2) a mixed alcohol; 3) a halogenating agent; and 4) a titanate compound. The magnesium alkoxide particle is used for preparing a catalyst for olefin polymerization.