| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for preparing a porous film having a high strength and an excellently uniform thickness while having a void content suitable as a separator for various batteries, particularly for a battery for an electric car. SOLUTION: There is provided a method for preparing a porous film comprising a step of melt-kneading a resin composition containing a polyolefin and a solvent, a step of extruding the resultant melted and kneaded product into a sheet, a step of forming it into a sheet by passing through a cooled sizing dice and a step of stretching and solvent removal, wherein a desired thickness of a sheet is attained by adjusting the width of a gap of the sizing dice.</p> |
