POLYOLEFIN MICROPOROUS FILM, POLYOLEFIN MICROPOROUS FILM ROLL, METHOD FOR PRODUCING POLYOLEFIN MICROPOROUS FILM OR POLYOLEFIN MICROPOROUS FILM ROLL, AND SEPARATOR FOR BATTERIES USING POLYOLEFIN MICROPOROUS FILM OR POLYOLEFIN MICROPOROUS FILM ROLL

摘要

The purpose of the present invention is to provide: a polyolefin microporous film having excellent productivity, which is capable of maintaining good film flatness even in the state of a wide and long roll; a polyolefin microporous film roll; a method for producing the polyolefin microporous film or the polyolefin microporous film roll; and a separator for batteries, which uses the polyolefin microporous film or the polyolefin microporous film roll. The present invention provides: a polyolefin microporous film which has a thickness of from 1 mum to 50 mum (inclusive), an air permeation resistance of from 50 seconds/100 mL to 500 seconds/100 mL (inclusive), and a shrinkage in the width direction of from -0.3% to 0.3% (inclusive) and a shrinkage in the longitudinal direction of from 0.0% to 1.5% (inclusive) at 40°C in 48 hours; a film roll which is obtained by winding up the polyolefin microporous film; a method for producing the polyolefin microporous film or the polyolefin microporous film roll; and a separator for batteries, which uses the polyolefin microporous film or the polyolefin microporous film roll.