Nixon & Vanderhye
Process of making porous films or sheets
 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.degree. to 150.degree. C. and a heat puncture temperature of not less than 160.degree. C., and a process for producing the same. 
Mitsubishi Chemical Corporation
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H01M H01M B29C C08L Y02E C08J B29K H01M B29C C08J C08J H01M C08J B29C B29K H01M C08J B29K C08J B29C B29C
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Toshio Keishin Kyosuke
Fujii Handa Watanabe