| abstract |
The present invention provides a battery separator in which a polyolefin microporous membrane having a width of 100 mm or more and a fluctuation range of F25 value in the width direction of 1 MPa or less, and at least one surface of the polyolefin microporous membrane are laminated The above-mentioned porous layer having a uniform thickness and improving electrode adhesion, the battery separator can be wound at a high density, and is suitable for increasing the capacity of a battery. A battery separator obtained by laminating a polyolefin microporous film and a porous layer containing a fluorine-based resin and inorganic particles on at least one side of the polyolefin microporous film, the width of the polyolefin microporous film being The variation range of the F25 value in the direction is 1 MPa or less, and the width of the polyolefin microporous membrane is 100 mm or more. Here, the F25 value is a value obtained by dividing the load value when the test piece is extended by 25% with a tensile tester by the cross-sectional area of the test piece. |