A process for producing a multilayer polytetrafluoroethylene porous membrane is disclosed, which process comprises at least two layers having different average pore diameters, the process comprising the steps of: filling the inside of a cylinder of an extruding mold distinctively with at least two kinds...http://www.google.es/patents/US5225131?utm_source=gb-gplus-sharePatente US5225131 - Process for producing multilayer polytetrafluoroethylene porous membrane and semisintered polytetrafluoroethylene multilayer structure
Process for producing multilayer polytetrafluoroethylene porous membrane and ...
