MULTILAYER POROUS MEMBRANE, AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a multilayer porous membrane having both of high safety and practicability when used particularly as a separator for nonaqueous electrolyte batteries.SOLUTION: The multilayer porous membrane is obtained by forming a porous layer containing an inorganic filler and a resin binder on at least one surface of a polyolefin resin porous film. The porous layer satisfies the following conditions (A) to (C) simultaneously. The wetting index (when measured according to JIS K-6768) of the surface of the polyolefin resin porous film is 40 mN/m or higher. The condition (A) is that the average particle size of the inorganic filler is 0.1-3.0μm. The condition (B) is that the resin binder accounts for 0.5-8% by volume fraction of the total volume of the inorganic filler and the resin binder. The condition (C) is that the porous layer accounts for 15-50% of the overall thickness of the multilayer porous membrane.