| abstract |
The present invention produces a laminated porous film which improves the stability of an aqueous dispersion of a metal oxide without lowering battery characteristics, while having high binding properties and excellent heat resistance. This laminated porous film exhibits excellent characteristics when used as a separator for batteries. This laminated porous film is produced by forming a porous coating layer on at least one outer surface of a resin porous film, which is formed of a single layer or a laminate of a plurality of layers, by applying a coating liquid that contains a metal oxide, a resin binder and a volatile acid thereto and drying the applied coating liquid. The coating liquid is prepared so that the difference between the pH (pH 1 ) of the coating liquid and the pH (pH 2 ) of the coating layer is not less than 2. |