| 摘要 |
PURPOSE:To obtain a semipermeable membrane with a supporting body and improved resistance to stripping and chemicals by forming a semipermeable body comprising a high molecular substance which is distributed continuously from the front surface to the rear surface of the supporting body. CONSTITUTION:A dope is prepd. by dissolving a high molecular substance such as polyether sulfone resin, etc. in a liquid mixture of a solvent such as N- methyl-2-pyrrolidone, etc. and a swelling agent such as lactic acid, etc. The dope is flowed on the inside surface of a supporting body which is formed cylindrically by welding a cylindrically superposed part of nonwoven cloth, etc. to prepare a sleeve membrane, which is allowed to stand in the air, then gelled by dipping in the water, and then taken out of the water. Thus, a semipermeable membrane provided with a supporting body with a three-layered structure having a semipermeable membrane 2-2, and 3-3 on the front and rear surface of the supporting body 4-4. The membrane prepd. by this process has improved resistance of the semipermeable membrane to stripping from the supporting body, and improved apparent alkali resistance and heat resistance. |
