COMPOSITE POROUS MEMBRANE, METHOD FOR PRODUCING COMPOSITE POROUS MEMBRANE AND BATTERY SEPARATOR USING SAME

摘要

Disclosed is a composite porous membrane which can achieve both an excellent adhesiveness of a heat-resistant resin layer and a small rise in gas permeation resistance even in the case of further reducing the thickness of membranes to be used, for example, battery separators. Specifically disclosed is a composite porous membrane comprising a porous membrane (A) formed of a polyolefin-based resin and a porous membrane (B) containing a heat-resistant resin, said porous membrane (B) being laminated on said porous membrane (A), wherein said porous membrane (A) has a thickness being within a specific range, an average pore size being within a specific range and a porosity being within a specific range and the thickness of the entire composite porous membrane is within a specific range, characterized in that, in said composite porous membrane, the peel strength at the interface between the specific porous membrane (A) and porous membrane (B) is within a specific range and the difference between the gas permeation resistance of the entire composite porous membrane and the gas permeation resistance of the porous membrane (A) is also within a specific range.