Process of making porous films or sheets

摘要

A porous film or sheet including a resin composition mainly of an ultra-high molecular weight polyethylene having a viscosity-average molecular weight of not less than 500,000, and having a thickness of 10 to 100 mu m, an air permeability of 20 to 2,000 sec/100 cc, a porosity of 15 to 80%, a pin puncture strength (per 25 mu m of film thickness) of not less than 120 g, a thermal-shut down temperature of 90 DEG to 150 DEG C. and a heat puncture temperature of not less than 160 DEG C., and a process for producing the same.