A heterophasic propylene polymerization material, including a propylene polymer component (I) and an ethylene-α-olefin copolymer component (II), the heterophasic propylene polymerization material satisfying features (i) to (v): (i) the heterophasic propylene polymerization material contains a xylene-soluble content by 20 wt % or more; (ii) xylene-soluble content in the heterophasic propylene polymerization material has a limiting viscosity [η].sub.CXS not less than 5 dL/g; (iii) a melt flow rate of the propylene polymer component (I) is 70 g/10 min or more; (iv) MFR of the heterophasic propylene polymerization material is not less than 5 g/10 min; and (v) the number of gels of 100 μm or more in diameter on a sheet for counting gels, including the heterophasic propylene polymerization material, is 1000 or less per 100 cm.sup.2 of the sheet.

A heterophasic propylene polymerization material, including a propylene polymer component (I) and an ethylene-α-olefin copolymer component (II), the heterophasic propylene polymerization material satisfying features (i) to (v): (i) the heterophasic propylene polymerization material contains a xylene-soluble content by 20 wt % or more; (ii) xylene-soluble content in the heterophasic propylene polymerization material has a limiting viscosity [η].sub.CXS not less than 5 dL/g; (iii) a melt flow rate of the propylene polymer component (I) is 70 g/10 min or more; (iv) MFR of the heterophasic propylene polymerization material is not less than 5 g/10 min; and (v) the number of gels of 100 μm or more in diameter on a sheet for counting gels, including the heterophasic propylene polymerization material, is 1000 or less per 100 cm.sup.2 of the sheet.

A process for preliminary polymerization may include washing a catalyst mud comprising a supported metallocene catalyst with at least one saturated hydrocarbon at a temperature from 0° C. to 40° C., a pressure from 20 to 40 kgf/cm.sup.2, and a residence time of at least 30 minutes; continuously feeding the washed catalytic mud to a continuous pre-polymerization reactor; and pre-polymerizing, in the continuous pre-polymerization reactor, ethylene and at least one C.sub.4 to C.sub.10 α-olefin as comonomer, with the washed catalytic mud, to produce a pre-polymer; wherein an average residence time in the continuous pre-polymerization reactor is more than 90 minutes and less than 240 minutes, a reactor temperature is from 10° C. to 50° C., and a reactor pressure from 20 to 40 kgf/cm.sup.2.

A process for preliminary polymerization may include washing a catalyst mud comprising a supported metallocene catalyst with at least one saturated hydrocarbon at a temperature from 0° C. to 40° C., a pressure from 20 to 40 kgf/cm.sup.2, and a residence time of at least 30 minutes; continuously feeding the washed catalytic mud to a continuous pre-polymerization reactor; and pre-polymerizing, in the continuous pre-polymerization reactor, ethylene and at least one C.sub.4 to C.sub.10 α-olefin as comonomer, with the washed catalytic mud, to produce a pre-polymer; wherein an average residence time in the continuous pre-polymerization reactor is more than 90 minutes and less than 240 minutes, a reactor temperature is from 10° C. to 50° C., and a reactor pressure from 20 to 40 kgf/cm.sup.2.

A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from 0.940 to 0.955 g/cm.sup.3, determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from 12 to 40; 3) Mz from 500,000 to 3,500,000 g/mol; 4) η.sub.0.02 from 80,000 to 300,000 Pa.Math.s; 5) HMWcopo index from 1 to 15; and 6) Mz/Mw*LCBI lower than 6.4.

A polyethylene composition for producing blow-molded hollow articles, having the following features: 1) density from 0.940 to 0.955 g/cm.sup.3, determined according to ISO 1183 at 23° C.; 2) ratio MIF/MIP from 12 to 40; 3) Mz from 500,000 to 3,500,000 g/mol; 4) η.sub.0.02 from 80,000 to 300,000 Pa.Math.s; 5) HMWcopo index from 1 to 15; and 6) Mz/Mw*LCBI lower than 6.4.

An injection molded article made from or containing a propylene-based composition made from or containing: T1) from 90 wt % to 50 wt % of a propylene homopolymer; and T2) from 10 wt % to 50 wt % of a polymer composition made from or containing A) 5-35% by weight of a propylene homopolymer or a propylene ethylene copolymer; B) 20-50% by weight of a copolymer of ethylene and a C.sub.3-C.sub.8 alpha-olefin containing from 0.1% to 20% by weight of alpha-olefin units; and C) 30-60% by weight of a copolymer of ethylene and propylene containing from 25% to 75% by weight of ethylene units.

An injection molded article made from or containing a propylene-based composition made from or containing: T1) from 90 wt % to 50 wt % of a propylene homopolymer; and T2) from 10 wt % to 50 wt % of a polymer composition made from or containing A) 5-35% by weight of a propylene homopolymer or a propylene ethylene copolymer; B) 20-50% by weight of a copolymer of ethylene and a C.sub.3-C.sub.8 alpha-olefin containing from 0.1% to 20% by weight of alpha-olefin units; and C) 30-60% by weight of a copolymer of ethylene and propylene containing from 25% to 75% by weight of ethylene units.

An object of the present invention is to provide a film for a capacitor such that the film excels in high-temperature dielectric breakdown voltage (high-temperature BDV) and has blocking resistance, and bleeding-out of, for instance, a nucleating agent is suppressed even after long-term storage. The present invention pertains to a multilayer polypropylene film for a capacitor, the film including a base layer composed of a propylene polymer composition containing a propylene homopolymer (X) and 0.0001 to 0.05 mass % of a polymer-based α-crystal nucleating agent (C), and a front layer or a back layer composed of a propylene-based polymer (Y) on at least one surface of the base layer, wherein the base layer and the front layer or back layer are stretched.

An object of the present invention is to provide a film for a capacitor such that the film excels in high-temperature dielectric breakdown voltage (high-temperature BDV) and has blocking resistance, and bleeding-out of, for instance, a nucleating agent is suppressed even after long-term storage. The present invention pertains to a multilayer polypropylene film for a capacitor, the film including a base layer composed of a propylene polymer composition containing a propylene homopolymer (X) and 0.0001 to 0.05 mass % of a polymer-based α-crystal nucleating agent (C), and a front layer or a back layer composed of a propylene-based polymer (Y) on at least one surface of the base layer, wherein the base layer and the front layer or back layer are stretched.