| 摘要 |
It is an object of the present invention to provide a microporous membrane which has a high homogeneity of structure and is excellent in permeability to a fluid, separating properties in separation of fine particles from the fluid, and mechanical properties, and a process for producing the microporous membrane. The above object has been achieved by a production process of a microporous membrane characterized by uniformly dissolving an olefin homopolymer or copolymer or a mixture of an olefin homopolymer or copolymer and a block or graft copolymer comprising olefin polymer sequences, hydrogenated butadiene polymer sequences or hydrogenated isoprene polymer sequences and sequences obtained from styrene, methyl methacrylate, vinyl acetate or vinyl chloride, in a specific solvent to obtain a one-phase solution, cooling the solution at a sufficient cooling rate to obtain a gel-like shaped product having the percolation structure due to liquid-liquid phase separation, and stretching the shaped product at a low ratio before or after extracting the solvent. The microporous membrane thus obtained has a homogeneous structure and satisfactory mechanical properties and is excellent in liquid permeability and separating properties for fine particles. <IMAGE> |
