| 摘要 |
PROBLEM TO BE SOLVED: To prepare a porous membrane excellent in air permeability, moisture permeability, and the like, and degradable by microorganisms in soil when discarded by casting on a support a coating material prepared from a polyactic acid resin and two specific kinds of solvents and soaking it in a non-solvent. SOLUTION: A polylactic acid resin is dissolved in a first solvent capable of dissolving this resin to give a first resin solution, which is diluted with a second solvent which has a high affinity for the first solvent but does not dissolve the polylactic acid resin to give a coating material for molding, which is cast on a support and subsequently soaked in a coagulant liquid mainly composed of a second solvent and water. As a first solvent are desirable cyclic ethers such as tetrahydrofuran, dioxane and acetone, and cyclic ethers in particular. As the second solvent are desirable DMF, NMP, DMAc, DMSO, and the like, and DMF in particular. As the coagulant liquid, is desirable water or a mixed solution of water with DMF. The ratio of the first solvent to the second solvent in the solvent mixture is desirably (10-49):(90-51).
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