Semipermeable composite membranes
First Claim
1. A semipermeable composite membrane consisting of a porous substance and a reinforcing material made of fibrous material embedded in the wall of the porous substance, at least one part of said porous substance forming a porous region of a network structure having pore sizes in the range from 500A to 5μ
- ;
said porous region containing a number of voids having diameters of 10μ
or greater; and
the ratio of water permeability of said membrane after one time treatment with hot water at 80°
C or after drying at 20°
C to the respective water permeability before said treatment being 0.3 or higher.
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Abstract
A semipermeable composite membrane which shows only a small reduction of water permeability even when it is subjected to one time hot water treatment or drying treatment is provided according to the method of the present invention. Said semipermeable composite membrane consists of a porous substance and a reinforcing material embedded therein. Said porous substance has a porous region of network structure at least in one part thereof and numbers of voids in said porous region. Said reinforcing material is a fabric in case of flat type membrane or a braid having a central hollow portion in case of hollow fiber type membrane which is embedded in the wall of the membrane. Said method comprises impregnating said reinforcing material with a polymer solution and treating the impregnated reinforcing material with a coagulating liquid.
71 Citations
9 Claims
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1. A semipermeable composite membrane consisting of a porous substance and a reinforcing material made of fibrous material embedded in the wall of the porous substance, at least one part of said porous substance forming a porous region of a network structure having pore sizes in the range from 500A to 5μ
- ;
said porous region containing a number of voids having diameters of 10μ
or greater; and
the ratio of water permeability of said membrane after one time treatment with hot water at 80°
C or after drying at 20°
C to the respective water permeability before said treatment being 0.3 or higher. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- ;
Specification