| abstract |
According to the present invention, a polyolefin microporous film and a battery separator are provided, the polyolefin microporous film is suitable for uniformly setting the thickness of the porous layer, and the thickness of the polyolefin microporous film is 3 μm or more and less than 7 μm, so The battery separator is obtained by uniformly providing the thickness of the porous layer on the polyolefin microporous membrane, and is suitable for increasing the capacity of batteries. The polyolefin microporous membrane has a variation range of F25 value in the longitudinal direction of 1 MPa or less, a thickness of 3 μm or more and less than 7 μm, and a length of 1000 m or more. (In this case, the F25 value represents the value obtained by dividing the load value when the test piece is extended by 25% with the tensile tester by the cross-sectional area of the test piece). |