Patent ID: 9034509
Filing Date: 2015-05-19
Classification: B32B,H01M,Y02E,Y02T

Abstract:
1. A method of producing a polyolefin microporous membrane, wherein a degree of crystallinity is from 60 to 85%, and a tie molecule volume fraction is from 0.7 to 1.7%, the method comprising: preparing a polyolefin solution by kneading from 1 to 35 parts by mass of polyolefin and from 65 to 99 parts by mass of mixed solvent composed of a volatile solvent and a nonvolatile solvent at from 190 to 220° C.; forming a gel composition by extruding the polyolefin solution through a die at a temperature from the melting point of the polyolefin to the melting point +60° C. and cooling the extruded polyolefin solution; removing the volatile solvent from the gel composition; drawing the gel composition; and removing the nonvolatile solvent from the gel composition.