| 摘要 |
PURPOSE: To secure a high filtration rate even under low filtration pressure by forming the section of a hollow-fiber membrane having a specified thickness with a three-dimensional reticular porous part having a specified pore diameter and a void having a specified size and so on. CONSTITUTION: The section of a hollow-fiber membrane having 50-500μm thickness is formed with a three-dimensional reticular porous part having substantially 0.05-1.7μm average pore diameter and a void part having 10-200μm size, and the area of the void part is controlled to 5-70% of the total cross-sectional area of the membrane. Meanwhile, an optionally-shaped micropore is formed in the inner and outer surfaces of the membrane, and the uniform porosity of the porous part in the section of the membrane except <=1/50 part of the total membrane thickness is set at 40-80%. Further, the fractional mol.wt. is controlled to 10,000-500,000, the strength at the point of tensile breakage to >=30kg/cm<2> , the intermembrane differential pressure to 1kg/cm<2> and the permeation rate of pure water at 25 deg.C to >=500l/(m<2> .hr).
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