POLYOLEFIN MULTILAYER MICROPOROUS MEMBRANE AND BATTERY SEPARATOR

摘要

Disclosed is a polyolefin multilayer microporous membrane composed of at least three layers. This polyolefin multilayer microporous membrane comprises first porous layers respectively composed of a polyethylene resin and constituting at least both surface layers, and a second porous layer containing a polyethylene resin and polypropylene and constituting at least one layer interposed between the two surface layers. This polyolefin multilayer microporous membrane is characterized in that the heat of fusion (Hm) of polypropylene as measured by a differential scanning calorimeter is not less than 90 J/g, and the polypropylene content is not more than 50% by mass when the total of the polyethylene resin and polypropylene in the second porous layer is taken as 100% by mass. ® KIPO & WIPO 2008