PURPOSE: To obtain the title semipermeable membrane having open cells in its thickness direction and having reticular structure without requiring an additive, etc., by forming the membrane from a mixture contg. a specified weight ratio of polyaryl resin and polysulfone resin.
CONSTITUTION: (A) The polyaryl resin having a repeating unit shown by formula I or (B) the polysulfone resin having a repeating unit shown by formula II or III are mixed in the weight ratio A/B=0.1W10 (in the formulas IWIII, R1WR4 are a 1W5C lower alkyl group). The mixture is dissolved in a solvent such as N-methylpyrrolidone to obtain a membrane forming soln., the soln. is cast on a glass sheet, the sheet is immediately dipped in the liq. coagulant consisting of water, N-methylpyrrolidone, etc., to gel the soln., the gel is washed with water to remove the solvent, and a membrane is formed. The semipermeable membrane thus obtained has the pores having ≤0.05μm pore diameter on the surface, and forms fibrillar structure in the cross-sectional direction of the membrane.
KIDA FUMIO
OKAMURA KIYOUJI
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