| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a porous membrane with a high performance of separating a liquid to be treated in a simple manner by mixing a polysulfone- based resin and a polyamide resin at respectively specified ratios. SOLUTION: About 55-95 wt.% polysulfone-based resin and about 45-5 wt.% polyamide-imide resin are mixed to form a porous polysulfone-based blended membrane. In this case, when the content ratio of the polyamide-imide resin is low, the improvement of the hydrophilic and the water permeation performance of a porous membrane is insufficient and when the content ratio is high, the surface of the porous membrane is fine, so that the water permeation performance is rather deteriorated. The membrane forming resin components used at the described ratios are prepared as a membrane forming stock solution obtained by dissolving the components in a aprotic polar solvent such as a dimethylformamide so that the sum of both components is equivalent to the concentration of about 15-35 wt.%. After that, the stock solution is formed into a flat membrane or a hollow fiber membrane by a routine wetting or a routine wetting/drying process, and the membrane is coagulated in a coagulating bath to be formed as the porous membrane.
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