| 摘要 |
To produce hollow fibers, a solution of a polymer, e.g. cellulose acetate, nitrocellulose, polysulfone, sulfonated polysulfone, polyether sulfone, polyacrylonitrile, polyamide, polyimide or polyphenylene oxide, is dissolved in a solvent and therefrom a hollow fiber is molded and is then immersed in a coagulating solution, e.g. water, an alcohol, glycol, glycerol. ether, aliphatic hydrocarbon or a mixture thereof. In a preferred embodiment there are simultaneously discharged through a triple-ring nozzle a poor solvent for the polymer, a good solvent for the polymer and a solution of the polymer (see Fig. 4). …<??>In the product, the pore size changes so as to gradually decrease from the outside of the fiber to its inside, and the minimum pore size gradually increases towards the opening of the interior of the fiber. The preferred pore size in the intermediate portion is 0.05 to 1 mu m. The fibers are useful for ultra-filtration. |
