PURPOSE: To prepare the titled membrane having microscope pores and excellent surface smoothness, and suitable as a membrane filter, a supporting membrane, etc., by the coagulation film-forming of a solution composed of a polysulfone polymer having low content of low-molecular weight component and its solvent in a coagulation bath.
CONSTITUTION: A polysulfone solution is prepared by dissolving a polysulfone polymer containing ≤0.1wt% of a low-molecular weight component having a molecular weight of 800W1,200, preferably a polymer having a molecular weight of 5,000W300,000 and containing ≥50mol% of the recurring unit of formula I or formula II, in a solvent which can dissolve ≥5wt% of said polymer at ≤50°C (especially N-methyl-pyrrolidone, etc.). The concentration of the polymer in the solution is 5W50wt%. The solution is formed to a flat film or hollow fiber, etc. The formed product is immersed and coagulated in a coagulation bath (water or a mixture or water and an organic liquid) to obtain a porous membrane having an average pore diameter of 100AW5μ and a void volume of the whole membrane of 30W90%.
KAWAGUCHI TAKEYUKI
MORI KOU
| JPS56126408A | 1981-10-03 |