LAMINATED POROUS FILM, SEPARATOR FOR BATTERY, AND BATTERY

摘要

The present invention is capable of providing a multilayer porous film used as a separator for a non-aqueous electrolyte secondary battery. A multilayer porous film which is obtained by laminating a coating layer that contains a filler and a resin binder on at least one surface of a polyolefin resin porous film that serves as a base layer. The ratio of the average particle diameter (Du) of the filler within 25% of the thickness of the coating layer from the surface of the multilayer porous film to the average particle diameter (Db) of the filler within 25% of the thickness of the coating layer from the interface with the base layer, namely, Du/Db is 1.2 to 10; and the average particle diameter (Du) is 0.5 μm or less.