Production of composite membrane for reverse osmosis

Abstract

Abstract PURPOSE:To obtain the membrane of considerably less fluctuations of performance industrially advantageously by making drying and heat treating temperatures specific. CONSTITUTION:The solution containing a film-formable in-situ polymerization type reaction component of monomer, oligomer or the product of initial reaction or the like which is a nonsolvent for a porous polysulfone substrate membrane is coated on the said substrate membrane. After this is first dried at a temperature of 140 deg.C or less, it is heat-treated at a temperature higher by about 10 deg.C or more than this drying temperature. This enables the production of the composite membrane of constant performance and quality with good reproducibility. Although the reasons for this are not sufficiently evident, it is presumed that the removal of the moisture contained in the substrate membrane and the solvent of the coating liquid takes place preferentially in the drying process, that the reaction components in the coating liquid having infiltered in the pores of the substrate membrane surface layer partly polymerize and the polymer thus formed is hard to receive thermal deformation and that this suppresses the shrinkage of the substrate membrane.

Inventors

• 👤 Tetsuo Watanabe
• 👤 Norio Harumiya
• 👤 Masaru Kurihara

Bibliographic Details