| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a porous film which suppresses increase of air permeability resistance and improves mechanical strength, and exhibits excellent output characteristics when being used as a separator.SOLUTION: When a porous sheet is subjected to press working for producing a porous film having a through hole, the press working is performed to a thickness direction of the porous sheet under conditions of (1) and (2), (1) press temperature is 100°C or more, and (2) press pressure is 1-100 kgf/cm in linear pressure.</p> |
