PURPOSE: To provide an interlayer construction consisting of more than two layers of high polymer membrane of different hole diameters, integrated and of non-fissility, by flowing and spreading more than two kinds of original liquid to produce membrane simultaneously or by turns, and dipping and hardening in the coagulating bath after setting more than two layers of coating layer on the supporting body.
CONSTITUTION: As the original liquid to produce membrane, solution in which polymers such as cellulose ester, polyamide, polyimide, polysulfone and others are solved with adequate solvent, or the liquid in which more than two kinds of polymer are blended is utilized. The original liquid to produce membrane is produced by solving polymers with a good solvent, or a solvent mixed with good one and non-soluble one, or mixture of several kinds of solvent having different solubility for polymer. Then the liquid is flowed and spread on the supporting body or directly in the coagulating liquid, washed and dried. Inorganic, organic or highly polymerized electrolyte can be added to control the porous construction. The said more than two kinds of starting liquid to produce membrane include the liquid in which different polymer components are solved, or the liquid consisting of the same polymer component solved in the different solvents, or the liquid of the same polymer component, of the same solvent and of different polymer density.
NARUO KYOICHI
SHINAGAWA YUKIO
