Patent ID: 8329766

Claim:
A production method of a functional membrane, comprising: an ion irradiation step in which a polymer film substrate is irradiated with high energy heavy ions at 10 4 to 10 14 ions/cm 2 , to form irradiation damages in said film substrate; an etching step in which after said ion irradiation step, said irradiation damages are subjected to chemical or thermal etching to form through pores in said film substrate; and a graft polymerization step in which the perforated film substrate thus obtained is added with monomers comprising group A monomers and 5 to 80 mol % group B monomers, wherein group A monomers each have a functional group and group B monomers are crosslinking agents, and said monomers are graft-polymerized only to the surface and pore wall of said film substrate by utilizing the active species still remaining in the positions of the latent tracks formed by being damaged by the ion irradiation or by utilizing active species newly generated by irradiation of any of radiation and plasma under vacuum or in an atmosphere of an inert gas.