Patent ID: 8889813

Claim:
A polyurethane resin, obtained from starting materials in the form of an isocyanate compound and a mixture or a solution composition comprised of an organic solvent in which the mixture is dissolved, wherein the mixture is a mixture of a sulfonate group-containing compound denoted by formula (1) with a protonic acid which is a sulfonic acid group-containing compound denoted by formula (2): wherein, in formula (1), X denotes a divalent linking group; each of R 1 and R 2 independently denotes an alkyl group comprising at least one hydroxyl group and equal to or more than three carbon atoms or an aralkyl group comprising at least one hydroxyl group and equal to or more than eight carbon atoms; and M denotes a cation other than hydrogen; wherein, in formula (2), X denotes a divalent linking group; each of R 1 and R 2 independently denotes an alkyl group comprising at least one hydroxyl group and equal to or more than three carbon atoms or an aralkyl group comprising at least one hydroxyl group and equal to or more than eight carbon atoms; and M denotes a hydrogen.