COMPOSITE MICROPOROUS FILM, AND PRODUCTION METHOD AND USE THEREOF

摘要

Disclosed is a composite microporous film which is obtained by applying a liquid mixture containing (a) a fluororesin which can be gelated, (b) a good solvent therefor and (c) a poor solvent therefor having a dipole moment of not more than 1.8 Debye to at least one surface of a polyolefin microporous film and drying it, thereby forming a coating layer composed of a porous body of the fluororesin on the surface. The composite microporous film has columnar through holes in the coating layer, and has an excellent balance among permeability, adhesion to electrodes, mechanical strength, thermal shrinkage resistance, shutdown characteristics and meltdown characteristics.