Patent EP0077923A1 successfully refreshed from Google Patents.
US3912834A
Expired / Lapsed
US
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Process for producing a selectively permeable composite
Assignee: Kanegafuchi Chemical Industry Co Ltd
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Filing: 1973-05-18
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Granted: 1975-10-14
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Expires: 1993-05-18
Abstract
Abstract A selectively permeable composite membrane is produced by providing a solution of a film-forming polymer, impregnating a liquid in which the film-forming polymer is insoluble to a porous backing material to the extent that at least one of surfaces of the backing material remains substantially free from the liquid while other portions thereof become wet, applying the solution of film-forming polymer to the surface of backing material to form a layer thereof, and gelling said layer of solution to form a membrane thereof.
Inventors
- 👤 Satoshi Imai
- 👤 Tamiyuki Eguchi
- 👤 Masaaki Shimokawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 00:52
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/10; B01D69/107; B01D69/1071; Y; Y10; Y10T; Y10T442/00; Y10T442/20; Y10T442/2033
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
93 words
IN A PROCESS FOR PREPARING A SELECTIVELY PERMEABLE, ASYMMETRIC, COMPOSITE MEMBRANE BY IMPREGNATING A POROUS, TEXTILE FABRIC BACKING MATERIAL WITH A NONSOLVENT FOR A FILM-FORMING POLYMER, APPLYING A SOLUTION OF SAID FILM-FORMING POLYMER IN A SOLVENT WHICH IS INERT TO SAID BACKING MATERIAL ONTO SAID BACKING MATERIAL AND GELLING THE FILM-FORMING POLYMER TO FORM SAID MEMBRANE, THE IMPROVEMENT WHICH COMPRISES: APPLYING A SOLUTION OF SAID FILM-FORMING POLYMER ONTO A SURFACE OF SAID BACKING MATERIAL WHICH IS SUBSTANTIALLY FREE OF SAID NONSOLVENT WHILE THE REMAINDER OF SAID BACKING MATERIAL IS IMPREGNATED WITH SAID NONSOLVENT.
Claim 2
Dependent Claim
93 words
IN A PROCESS FOR PREPARING A SELECTIVELY PERMEABLE, ASYMMETRIC, COMPOSITE MEMBRANE BY IMPREGNATING A POROUS, TEXTILE FABRIC BACKING MATERIAL WITH A NONSOLVENT FOR A FILM-FORMING POLYMER, APPLYING A SOLUTION OF SAID FILM-FORMING POLYMER IN A SOLVENT WHICH IS INERT TO SAID BACKING MATERIAL ONTO SAID BACKING MATERIAL AND GELLING THE FILM-FORMING POLYMER TO FORM SAID MEMBRANE, THE IMPROVEMENT WHICH COMPRISES: APPLYING A SOLUTION OF SAID FILM-FORMING POLYMER ONTO A SURFACE OF SAID BACKING MATERIAL WHICH IS SUBSTANTIALLY FREE OF SAID NONSOLVENT WHILE THE REMAINDER OF SAID BACKING MATERIAL IS IMPREGNATED WITH SAID NONSOLVENT.
Claim 3
Dependent Claim
14 words
A process according to claim 1, wherein said backing material is a filter cloth.
Claim 4
Dependent Claim
31 words
A process according to claim 2 wherein said filter cloth is a polymeric material selected from the group consistng of polyolefins, polyamides, polyesters, polyvinyl chlorides, polyvinylidene chlorides, cellulosic polymers and polyacrylates.
Claim 5
Dependent Claim
15 words
A process according to claim 3 wherein said filter cloth is a polyethylene filter cloth.
Claim 6
Dependent Claim
15 words
A process according to claim 3 wherein said filter cloth is a polypropylene filter cloth.
Claim 7
Dependent Claim
19 words
A process according to claim 3 wherein said filter cloth has a thickness of about 0.25 to 0.5 mm.
Claim 8
Dependent Claim
29 words
A process according to claim 1 wherein said film-forming polymer is selected from the group consisting of polyvinyl chloride, copolymers of vinyl chloride with acrylonitrile, polysulfone and cellulose nitrate.
Claim 9
Dependent Claim
13 words
A process according to claim 7 wherein said film-forming polymer is polyvinyl chloride.
Claim 10
Dependent Claim
27 words
A process according to claim 8 wherein the polyvinyl chloride is dissolved in a solvent selected from the group consisting of dimethylformamide, tetrahydrofuran, cyclohexanone and mixtures thereof.
Claim 11
Dependent Claim
21 words
A process according to claim 8 wherein said nonsolvent is selected from the group consisting of water, methanol anD mixtures thereof.
Claim 12
Dependent Claim
11 words
A process according to claim 10 wherein the nonsolvent is methanol.
Claim 13
Dependent Claim
23 words
A process according to claim 1 wherein said film-forming polymer is selected from the group consisting of cellulose acetate, polyelectrolytes and aromatic polyamides.
Claim 14
Dependent Claim
32 words
A process according to claim 1 wherein the film-forming polymer is dissolved in a solvent selected from the group consisting of acetone, cyclohexanone, formamide, dimethyl formamide, tetrahydrofuran, cyclohexane, dimethylsulfoxide and mixtures thereof.
Claim 15
Dependent Claim
23 words
A process according to claim 1 wherein said nonsolvent is selected from the group consisting of water, methanol, ethanol, propanol and mixtures thereof.
Claim 16
Dependent Claim
23 words
A process according to claim 2 wherein said filter cloth is polyolefin, said film-forming polymer is polyvinyl chloride and said nonsolvent is methanol.
Claim 17
Dependent Claim
29 words
A process according to claim 1 wherein said application is effected by selective evaporation of said nonsolvent from said surface portion of a backing material saturated with said nonsolvent.
Claim 18
Dependent Claim
31 words
A process according to claim 1 wherein said application is effected by impregnating the nonsolvent from the side of said backing material opposite that to which the polymer solution is applied.
Claim 19
Dependent Claim
28 words
A process according to claim 1 wherein said nonsolvent is miscible with water, and said gelling is effected by immersing the resultant backing material in a water bath.
Claim 20
Dependent Claim
11 words
A process according to claim 1 conducted as a continuous operation.
Claim 21
Dependent Claim
41 words
A selectively permeable, asymmetric composite membrane having mechanical strength, selective permeability and flux rate properties suitable for use in ultrafiltration or reverse osmosis, consisting essentially of a porous, flexible, textile fabric backing material prepared according to the process of claim 1.
References Cited (Backward Citations)
US1720670A
Cited
US3342729A
Cited
US3429957A
Cited
US3549016A
Cited
US3544358A
Cited
US3494470A
Cited
US3556305A
Cited
US3648845A
Cited
US3762566A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-13 | 1979-04-14 | 1979-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-13 | 1983-04-14 | 1983-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-13 | 1987-04-14 | 1987-10-14 | $7700.00 | Window Closed / Lapsed |