| 摘要 |
PURPOSE:To increase the rigidity, the pressure resistance, and water-permeating speed to a degree sufficient for practical use, by installing a permeable membrane at the inside or outside surface of a tube made of multilayer porous fibrous base materials, and by bonding the base materials to each other with porous bonding layers which have quality the same as that of the membrane. CONSTITUTION:A permeable membrane 6 is formed on the inside surface of a tube composed of two layers made of porous, fibrous base materials 4, 5, at the same time, the base materials 4, 5 are bonded to each other with a bonding medium 7 which has a quality similar to that of the membrane 6. The membrane 6 has many fine pores. The term ''similar quality to that of the membrane'' means that the bonding medium has a porous structure which has many fine pores and has physical property the same as, or similar to, that of the permeable membrane. Simultaneous formation of the bonding layer and the permeable membrane with polymer soln. for forming the permeable membrane makes the bonding layer and the membrane from the same material, thereby increasing their rigidity, press. resistance, water- permeating speed to a degree sufficient for practical use. |
