| 摘要 |
PURPOSE:To obtain a uniform porous membrane of any desired thickness, by arranging a liquid layer of a dissolved plastic and other two liquid layers in strata by a difference in specific gravities and passing a core material through the liquid layers. CONSTITUTION:A first liquid layer 2 comprising a solution formed by dissolving a plastic in a solvent A, a second liquid layer 3 comprising a solvent B incompatible with the solvent A of the first liquid layer and a third liquid layer 4 comprising a solvent C incompatible with the solvent B of the second layer 3 are settled by a difference in their specific gravities in order of the first liquid layer 2, the second liquid layer 3 and the third liquid layer 4 (this is a case in which the specific gravities of the solvents A, B and C, dA, dB and dC are in order of dA>dB>dC). A core material 5 is passed (ascended in this instance) from the first liquid layer 2 to the third liquid layer 4 to deposit a porous membrane around the periphery of the core material 5. A porous membrane of any desired thickness can be obtained by varying the kinds of the liquid layers, the concentration and viscosity of the first liquid layer, the thickness of the second liquid layer and the kind of moving speed of the core material.
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