| abstract |
A heat resistant microporous membranencontaining a thermoplastic resin having a crystallinenmelting point of 140-300°C and having a layer structurenformed in the direction of membrane thickness, saidnlayer structure containing 5-100% of a layer defined bynthe following (A) and 95-0% of a layer defined by thenfollowing (B):n (A) a layer in which the micropores arenintra-spherulitic voids, and (B) a layer in which the micropores arenintra-spherulitic voids and inter-spherulitic voids. |