US4454176A
Expired / Lapsed
US
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Supported reverse osmosis membranes
Assignee: EIDP Inc
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Filing: 1982-10-14
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Granted: 1984-06-12
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Expires: 2002-10-14
Abstract
Abstract Preparation of supported reverse osmosis membranes on a woven, unsized, porous support using dimethylacetamide solvent and a lithium nitrate or chloride or magnesium chloride salt.
Inventors
- 👤 John J. Buckfelder
- 👤 Henry M. Schleinitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:35
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/10; B01D69/107; B01D69/1071; B01D67/00; B01D67/0002; B01D67/0009; B01D67/00091; B01D71/00; B01D71/06; B01D71/56; B01D2323/00; B01D2323/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
124 words
In a process for the preparation of a reverse osmosis membrane by coating a solution of aromatic polyamide, solvent, and modifying salt onto a porous support, evaporating a portion of the solvent and coagulating the aromatic polyamide in the resulting membrane in a nonsolvent for the aromatic polyamide, the improvement wherein the porous support is a woven, unsized, polyester or aromatic polyamide fabric, the solvent in the solution comprises at least about 80 percent dimethylacetamide, the modifying salt comprises about 20-60 weight percent, based on the aromatic polyamide in solution, of lithium nitrate, lithium chloride or magnesium chloride, and the solution, as it is coated onto the support, exhibits a viscosity of 100 to 400 poise with little tendency to permeate the support fabric.
Claim 2
Dependent Claim
124 words
In a process for the preparation of a reverse osmosis membrane by coating a solution of aromatic polyamide, solvent, and modifying salt onto a porous support, evaporating a portion of the solvent and coagulating the aromatic polyamide in the resulting membrane in a nonsolvent for the aromatic polyamide, the improvement wherein the porous support is a woven, unsized, polyester or aromatic polyamide fabric, the solvent in the solution comprises at least about 80 percent dimethylacetamide, the modifying salt comprises about 20-60 weight percent, based on the aromatic polyamide in solution, of lithium nitrate, lithium chloride or magnesium chloride, and the solution, as it is coated onto the support, exhibits a viscosity of 100 to 400 poise with little tendency to permeate the support fabric.
Claim 3
Dependent Claim
11 words
A process for claim 1 wherein the woven fabric is polyester.
Claim 4
Dependent Claim
11 words
A process of claim 2 wherein the polyester is polyethylene terephthalate.
Claim 5
Dependent Claim
14 words
A process for claim 1 wherein the modifying salt consists essentially of lithium nitrate.
Claim 6
Dependent Claim
28 words
A process for claim 1 further comprising annealing the resulting supported membrane in water at a temperature of about 50°-75° C. for a period of about 15-60 minutes.
Claim 7
Dependent Claim
22 words
A process of claim 5 further comprising contacting the supported membrane with an aqueous solution of about 100 ppm polyvinyl methyl ether.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-06-12 | 1987-12-12 | 1988-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-12 | 1991-12-12 | 1992-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-12 | 1995-12-12 | 1996-06-12 | $7700.00 | Window Closed / Lapsed |