PURPOSE: To obtain a separation membrane from a polymer with good heat resistance having repeating units consisting of at leat 60% specific component.
CONSTITUTION: Polyester or polyether ester having repeating units consisting of at least 60wt% compoent of the formula is prepared from a phonshonic acid or phosphoric acid, a dihalide of a dicarboxylic acid and glycols by an interfacial polymerization method or the like and the obtained polymer is dissolved in an aprotic solvent and the resulting solution is formed into a homogenous, or a symmetric or an asymmetric porous membrane to prepare a selective separation membrane having a thickness of pref. 0.1W300μ. As an org. high-molecular material of a porous membrane used as a support, cellulose acetate, polysulfone or polyvinyl fluoride are used. The thickness of the thin film coated on the membrane is pref. 0.01W10μ. In the formula, R1 is a 1W18C hydrocarbon group, R2 and R3 are each H, Cl, Br or a monovalent 1W4C hydrocarbon group and a is 0 or 1.
KONAGAYA JIYUUJI
ENDOU SEIJI
