MANUFACTURING METHOD OF DRAWN RESIN POROUS MEMBRANE

摘要

PROBLEM TO BE SOLVED: To provide a resin porous membrane useful as a separation membrane such as a liquid filtrating membrane and a battery separator while maintaining a high liquid permeability by preventing decline of porosity in a dense layer in the vicinity of the surface layer controlling the separation performance at the time of a drawing operation for reinforcement of the mechanical strength, increase of the porosity, and the like.SOLUTION: The manufacturing method of a drawn resin porous membrane comprises a step of drawing a resin porous film in a state selectively wetted with a wetting liquid by 5 μm or more from its outer surface and 1/2 of the membrane thickness or less.