| 摘要 |
A hollow fiber microporous membrane of a polyolefin having a polyvinyl alcohol chemically bonded to the inner and outer surfaces of the hollow fiber membrane and the surfaces defining the pores thereof exhibits a good hydrophilic property as well as good chemical resistance, mechanical strength, water permeation performance and durability. This membrane has an average pore diameter of 0.01 to 5 .mu.m and a porosity of 20 to 80%. The polyvinyl alcohol/polyolefin composition ratio is constant in the membrane thickness direction of the hollow fiber, the oxygen/carbon atomic ratio X on the outer surface of the hollow fiber microporous membrane is 10 to 50%, and the condition defined by the ratio X/2 ? Y is satisfied between said oxygen/ carbon atomic ratio X and the oxygen/carbon atomic ratio Y in the entire microporous membrane. The membrane is prepared by irradiating a hollow fiber microporous membrane of a polyolefin with ionizing radiations, reacting the membrane with vinyl acetate and then hydrolyzing the membrane.
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