US3724672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Asymmetric hollow fiber membranes and method of fabrication
Assignee: Individual
•
Filing: 1970-07-27
•
Granted: 1973-04-03
•
Expires: 1990-07-27
Abstract
Abstract This invention is directed to hollow filament membranes derived from esters of cellulose and characterized by a density gradient in the filament wall structure. When employed in reverse osmosis operations the filaments exhibit extraordinary flux and rejection properties. A continuous fabricating method is also provided which comprises continuously extruding filaments into a controlled evaporation zone thence directing the filaments into a cold water coagulation bath, thereafter passing the same to a wash bath and finally to an annealing zone.
Inventors
- 👤 R Leonard
- 👤 J Bashaw
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:20
CPC Classifications
D; D01; D01D; D01D5/00; D01D5/24; B; B01; B01D; B01D69/00; B01D69/08; D01D5/06; D01F; D01F2/00; D01F2/24; D01F2/28
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
23 words
The method of claim 1, wherein said cellulose ester is cellulose acetate and wherein said solvent is a mixture of formamide and acetone.
Claim 2
Dependent Claim
18 words
The method of claim 1, wherein said annealing temperature is in the range of about 75* to 90*C.
Claim 3
Dependent Claim
23 words
A reverse osmosis membrane comprised of asymmetric hollow filaments derived from an ester of cellulose and produced by the method of claim 1.
References Cited (Backward Citations)
US2988418A
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US3228876A
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US3439074A
Cited
US3412184A
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US3592953A
Cited
US3674628A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |