| 摘要 |
PURPOSE:To obtain a selectively permeable membrane of which the ultrafiltration speed of water is rapid and a removal rate of high-molecular substance is high even at low pressure, by a method wherein physical properties and performance of the selectively permeable membrane, whose principal ingredient is a cellulose ester, are adjusted by a membrane manufacturing solvent, whose main component is dimethyl sulfoxide. CONSTITUTION:A membrane manufacturing solvent consisting of a cellulose ester, such as cellulose acetate, and dimethyl sulffoxide is cast, and a membrane is formed and solidified by a coagulating liquid. The ratio of the weight of dimethyl sulfoxide and that of the cellulose ester in the membrane manufacturing solvent is adjusted at that time, and a selectively permeable membrane is obtained of which the percentage of voids is 40-95%, the ultrafiltration speed of water 1-2,000ml/m<2>. hr.mm.Hg, a removal rate of low-molecular substances 0-50%, a removal rate of intermediate-molecular substances 0-100% and a removal rate of high-molecular substances 50-100%. The membrane of which the ultrafiltration speed of water is rapid and the removal efficiency of high-molecular substances is excellent is obtained even at such a low operating pressure. |
