Patent ID: 8394309

Claim:
A method for producing a resin film comprising casting a dope having a resin and an organic acid monoglyceride represented by the following formula (1) on a metal support to prepare a dope film, wherein the ratio of the organic acid monoglyceride to the resin in the dope is from 0.1 to 20% by mass; and peeling away the dope film from the metal support: Formula (1) X-L- (R 1 ) n wherein: X represents an acid group wherein the acid dissociation constant is 5.5 or less; L represents a di or more valent linking group; R 1 represents an alkyl group having from 6 to 30 carbon atoms, an alkenyl group having from 6 to 30 carbon atoms, an alkynyl group having from 6 to 30 carbon atoms, an aryl group having from 6 to 30 carbon atoms or a from 6 to 30 membered heterocyclic group, and each group may have a further substituent; and n represents the number expressed by: (the valent number of L) −1; and further wherein the organic acid monoglyceride is (i) one having a structure in which one of the three hydroxyl groups of glycerin forms an ester bond with a fatty acid, a second hydroxyl group is an unsubstituted hydroxyl group and the third hydroxyl group forms an ester bond with a polycarboxylic acid and has an acid group derived from the polycarboxylic acid, or (ii) a polycarboxylic acid monoglyceride which has at least one unsubstituted carboxyl group of the polycarboxylic acid moiety and in which the other carboxyl groups are substituted with a monoglyceride.