POLYOLEFIN MULTILAYER MICROPOROUS MEMBRANE AND BATTERY SEPARATOR

摘要

A multi-layer, microporous polyolefin membrane having at least three layers, which comprises first microporous layers made of a polyethylene resin for constituting at least both surface layers, and at least one second microporous layer comprising a polyethylene resin and polypropylene and disposed between both surface layers, the heat of fusion (”H m ) of the polypropylene measured by differential scanning calorimetry being 90 J/g or more, and the polypropylene content in the second microporous layer being 50% or less by mass based on 100% by mass of the total of the polyethylene resin and the polypropylene.