MICROPOROUS POLYOLEFIN FILM, SEPARATOR FOR BATTERY, AND PRODUCTION PROCESSES THEREFOR

摘要

A microporous polyolefin film which has a width of 100 mm or greater and has a width of variations in transverse-direction F25 value of 1 MPa or less, and which is suitable for forming a porous layer reduced in thickness unevenness. (The term F25 value means a value obtained by examining a test piece using a tensile tester to measure a load at the time when the test piece has elongated by 25% and dividing the load by the cross-sectional area of the test piece.)