| abstract |
PURPOSE: Titled porous membrane made by removing almost all of silica fine particles from polyvinyl alcohol films containing the same, thus suitably being used as a filtering material because they have uniform porous structure with specified average size and void volume and high permeability. n CONSTITUTION: Fine particles of silica, preferably of 0.1W10μ particle size, is mixed with a polymer dope of polyvinyl alcohol and the dope is made into hollow fiber of film. Then, the film is treated with an aqueous alkali to extract more than 90wt% of silica fine particles, preferably more than 99wt% to produce the objective porous film with uniform pore structure of 0.01W50, preferably 0.05W20μ average particle size and more than 60%, preferably more than 70% void volume. When needed, the film is crosslinked by treatment with glutaraldehyde before the alkali extraction to increase the pressure and heat resistance. n COPYRIGHT: (C)1981,JPO&Japio |