| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a polyolefin microporous film having good cycle characteristics and excellent in electrolyte injection property; a battery separator obtained by the production method; a nonaqueous electrolyte secondary battery having the battery separator.SOLUTION: A method for producing a polyolefin microporous film includes: a step 1 of kneading a polyolefin resin and a plasticizer to form a kneaded product; a step 2 of processing the kneaded product into a sheet-like molded body; a step 3 of rolling the sheet-like molded body to obtain a rolled body; and a step 4 of extracting a plasticizer from the rolled body and stretching the rolled body, where in the step 3, a film thickness maintenance rate which is defined as film thickness maintenance rate=(film thickness after rolling/film thickness before rolling)×100, is 35% or more and 90% or less.SELECTED DRAWING: None |
