raben, dimethylol dimethylhydantoin, imidazolinium urea; and a copolymer of e.g. a monomer (V) of the formula (V): wherein R1 is a hydrogen atom or a methyl group, R2 is a C1-8 alkylene group, R3 is a C1-18 alkyl group, and X1 is a halogen atom such as a chlorine atom, a bromine atom or an iodine atom, or a monomer (VI) of the formula (VI): wherein R4 is a hydrogen atom or a methyl group, R5 is a