| abstract |
In the present invention, a polyolefin microporous membrane having a width of 100 mm or more and a fluctuation width of F25 in the width direction of 1 mm 2 or less and a porous layer for improving electrode adhesiveness having a uniform thickness on at least one side thereof are stacked, and can be wound with high density. And a battery separator suitable for increasing the capacity of the battery. A separator for a battery in which a porous layer containing a fluorine-based resin and inorganic particles is laminated on at least one surface of a polyolefin microporous membrane having a width of 100 mm or more in which the fluctuation width of the F25 value in the width direction is 1 mm 2 or less. And the load value when the test piece is stretched by 25% divided by the cross-sectional area of the test piece) |