METHOD FOR PRODUCING POLYOLEFIN POROUS FILM, AND LAMINATED POROUS FILM

摘要

Provided is a method for producing, with good reproducibility and high efficiency, a polyolefin porous film having a porous structure appropriate for the separator of a cell without using a special device. The method for producing a polyolefin porous film is a method for producing a polyolefin porous film by conveying a starting polyolefin sheet having micropores to inside the furnace of a tenter-type stretching device and subjecting the sheet to tenter stretching in multiple stretching regions inside the furnace, wherein the multiple stretching regions include at least two stretching regions having different film-widening speeds, the temperature of the stretching region having a fast film-widening speed from the at least two stretching regions is lower than that of the stretching region having a slow film-widening speed, and the stretching region having the fastest film-widening speed is disposed before the stretching region having the slowest film-widening speed.