FILM-FORMING SOLUTION AND FILM-FORMING METHOD

摘要

PROBLEM TO BE SOLVED: To produce the film-forming soln. phase separating at both of low temp. side and high temp. side and to produce a membrane using the soln. and high in water permeability and uniform in surface fine pore diameter. SOLUTION: Polysulfon based resin, hydrophilic polymer I having an average mol.wt. of at least 1000-2000 and the hydrophilic polymer II having the average mol.wt. of 10000-1200000 are dissolved to a mutual solvent so that a concn. ratio of the hydrophilic polymer I to the hydrophilic polymer II may be 5-12 to form the film-forming soln. Such a film-forming soln. is the soln. phase separating at both of low temp. side and high temp. side, and the film obtained by using the film-forming soln. has high water permeability and the film is excellent in uniformity of the surface fine pore diameter.