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AssigneesChisso Corporation, Chisso Petrochemical Corporation
InventorsHideshi Sakamoto, Junichi Yamauchi, Takashi Shimpuku
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Purpose of the invention—The purpose of the invention is to provide a porous polyolefin membrane consistent with a simple composition that may be characterized by a small pore diameter and a high porosity by simplifying the manufacturing process to facilitate uniform dispersion of the components. Means to achieve the purpose—A porous polyolefin membrane is formed by melting and kneading a specific resin (C) which composition containing a polyolefin resin consisting of a crystalline polypropylene (A) and a propylene-α-olefin copolymer (B), dispersed in said crystalline polypropylene (A), to obtain a film-shaped melt, and forming a membrane from the said melt with specific conditions, followed by stretching of said membrane at least in one direction, which contains continuous pores in the region consisting of said copolymer (B).
A porous polyolefin membrane formed by melting and kneading a resin composition containing a polyolefin resin (C) consisting of 30-90 wt % crystalline polypropylene (A) and 10-70 wt % propylene-α-olefin copolymer (B), dispersed in said crystalline polypropylene (A), wherein a ratio of the melt flow rate of said crystalline polypropylene (A) MFRpp to that of said propylene-α-olefin copolymer (B) MFRRC is between 0.1 and 10, to obtain a film-shaped melt, and forming a membrane from said melt, followed by stretching said membrane at least in one direction, which contains continuous pores in the region consisting of said copolymer (B).
A porous polyolefin membrane formed by melting and kneading a resin composition substantially containing only a polyolefin resin (C) consisting of 30-70 wt % crystalline polypropylene (A) and 30-70 wt % propylene-α-olefin copolymer (B), dispersed in said crystalline polypropylene (A), wherein the ratio of the melt flow rate of said crystalline polypropylene (A) MFRpp to that of said propylene-α-olefin copolymer (B) MFRRC is higher than 10 and equal to or less than 1,000, to obtain a film-shaped melt, and forming a membrane from said melt, followed by stretching said membrane at least in one direction, which contains continuous pores in the region consisting of said copolymer (B).
Dependencies are inferred from the claim text.