PRODUCTION METHOD FOR SEPARATOR FOR NONAQUEOUS ELECTROLYTIC ELECTRICITY STORAGE DEVICE AND PRODUCTION METHOD FOR NONAQUEOUS ELECTROLYTIC ELECTRICITY STORAGE DEVICE

Provided is a separator for nonaqueous electrolyte electricity storage devices that includes an improved porous epoxy resin membrane. At least one compound selected from a carboxylic acid, a carboxylic acid salt, a carboxylic acid anhydride, and a carboxylic acid halide, is brought into contact with a porous epoxy resin membrane, and thus hydroxyl groups contained in the porous membrane are reacted with the compound to produce carboxylic acid ester bonds. As a result of this treatment, the amount of active hydroxyl groups present in the porous epoxy resin membrane is reduced, and the porous epoxy resin membrane becomes suitable as a separator for nonaqueous electrolyte electricity storage devices. An epoxy resin sheet yet to be made porous may be subjected to reaction with the compound.