Patent ID: 11344848

Abstract:
Provided are a porous film having excellent surface smoothness and a method for producing the same. The surface roughness of a porous film of polyvinylidene fluoride, polyethersulfone, polyimide and/or polyamide-imide is Ra 30,000 Å or less. The opening diameter of the porous film is preferably from 100 nm to 5000 nm. The method for producing a porous film preferably includes a step for kneading a varnish containing fine particles and at least one resin selected from the group consisting of polyvinylidene fluoride, polyether sulfone, polyamic acid, polyimide, polyamide-imide precursor, and polyamide-imide. The varnish preferably has a viscosity at 25° C. of 0.1-3 Pa·s, a solids fraction concentration of 10-50 mass %, and a fine particle average particle size of 10-5000 nm.