MICROPOROUS FILM, BATTERY SEPARATOR, PRODUCTION METHOD OF THE FILM, AND RESIN COMPOSITION FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY SEPARATOR

摘要

PROBLEM TO BE SOLVED: To provide a microporous film which is obtained by using a polyolefin and a PAS resin having a melting point within 180-280°C and has excellent thermal shrinkage resistance and to provide another microporous film particularly for nonaqueous electrolyte secondary battery separators, production methods of the microporous film and the microporous film particularly for nonaqueous electrolyte secondary battery separators, and a resin composition for nonaqueous electrolyte secondary battery separators.SOLUTION: The microporous film contains the PAS resin having the melting point within 180-280°C and the polyolefin. The PAS resin (a) has an acicular structure. The production method of the microporous film comprises the steps of: melting/kneading the PAS resin and the polyolefin at the temperature equal to or higher than the melting point of the PAS resin to obtain a resin composition; melting/kneading the obtained resin composition and a pore forming agent at the temperature equal to or higher than the melting point of the PAS resin to obtain a melted/kneaded product; and forming a sheet from the melted/kneaded product heated to the temperature equal to or higher than the melting point of the PAS resin (a) to obtain the sheet (γ) containing the PAS resin (a) having the acicular structure.