METHOD FOR PRODUCING BIAXIALLY STRETCHED POLYOLEFIN-BASED POROUS FILM, AND BIAXIALLY STRETCHED POLYOLEFIN-BASED POROUS FILM

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a porous film, capable of producing the porous film in high productivity.;SOLUTION: The method for producing a biaxially stretched polyolefin-based porous film stretched by a dry method is provided by comprising an MD (machine direction) cold stretching step of MD-cold stretching the film constituted by the polyolefin-based resin and a TD (transverse direction) cold stretching step of TD-cold stretching the film at a stretching temperature satisfying a condition expressed by formula (1): (Tg+20)≤T≤(Tm-30) [wherein, T is the stretching temperature (unit:°C), Tg is the glass transition temperature (unit:°C) of the film, and Tm is the melting point (unit:°C) of the film].;COPYRIGHT: (C)2012,JPO&INPIT