Patent ID: 9393530
Filing Date: 2016-07-19
CPC Classification: B01D,C08J

Claim Text:
1. A process for production of a porous membrane having a three-dimensional network structure in which macrovoids are suppressed comprising: (i) layering a film-forming dope that contains a polymer (A) that forms a membrane base, a polyvinylpyrrolidone (B) and a solvent (C) into a single layer or more layers, (ii) solidifying said film-forming dope by immersing the film-forming dope in a solidifying fluid that is a non-solvent with respect to the polymer (A) and is a good solvent with respect to the polyvinylpyrrolidone (B) to obtain said porous membrane, (iii) decomposing and removing the polyvinylpyrrolidone (B) which remains in said porous membrane until 2 mass % or less with respect to a mass of said polymer (A) by immersing said porous membrane in an aqueous solution comprising an oxidizing agent, and (iv) drying said porous membrane after step (iii), a viscosity of the film-forming dope at a membrane production temperature is 120 to 500 Pa·s.