MICROPOROUS FILM AND METHOD FOR PRODUCING THE SAME

Provided is a microporous film which is made of a thermoplastic resin composition comprising (a) 100 parts by mass of a polypropylene resin and (b) 5 to 90 parts by mass of a polyphenylene ether resin, and which has a sea island structure comprising a sea portion comprising the polypropylene resin as a principal component and an island portion comprising the polyphenylene ether resin as a principal component, wherein pores are formed at an interface between the sea portion and the island portion and within the sea portion.