MICROPOROUS FILM AND METHOD FOR PREPARATION THEREOF

摘要

A microporous film being made of a polyethylene resin of a weight average molecular weight of less than 380,000 and having a porosity of 50 to 95 % and an average pore diameter of 0.01 to 1 mu m, which comprises a framework of a three-dimensional network in which macrofibrils having an average diameter of 0.2 to 1 mu m are connected with one another over the whole microporous film and openings being formed by the framework and having an average diameter of 0.1 mu m or more and less than 3 mu m, wherein the opening forms a screen through the bridging with microfibrils being branched from the macrofibrils and having an average diameter of 0.01 mu m or more and less than 0.2 mu m.