| abstract |
Provided is a composite porous film having both adhesiveness in a resin layer with superior heat resistance and a low degree of increase in air resistance.nIn this composite porous film, a porous film (B) containing a heat resistant resin is laminated on the surface of a polypropylene resin in the outermost layer of a porous film (A) formed from at least one layer and having at least one outermost layer formed from a polypropylene resin. The composite porous film is characterized by satisfying a specific range of peel strength at the interface between the porous film (A) and the porous film (B) as well as a specific range for the difference between the air resistance of the composite porous film as a whole and the air resistance of the porous film (A) when the porous film (A) satisfies a specific range of pore size and porosity. |