US3607329A
Expired / Lapsed
US
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Cellulose acetate butyrate semipermeable membranes and their production
Assignee: United States Department of the Interior
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Filing: 1969-04-22
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Granted: 1971-09-21
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Expires: 1989-04-22
Abstract
Abstract Semipermeable membranes are produced by casting a solution consisting essentially of cellulose acetate butyrate, triethyl phosphate, a flux promoter and an organic solvent into a film, and subsequently gelling the film by immersion in water. The membranes of the invention find particular utility in separation of solutes from solutions by osmosis or reverse osmosis.
Inventors
- 👤 Serop Manjikian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:21
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/08; B01D71/12; B01D71/14; B01D71/18; B01D67/00; B01D67/0002; B01D67/0009; B01D67/0011; B01D2323/00; B01D2323/12
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
28 words
A method according to claim 1 in which the cellulose acetate butyrate in (a) contains about 17 percent combined butyryl groups and about 29.5 percent combined acetyl groups.
Claim 2
Dependent Claim
28 words
A method according to claim 1 in which the cellulose acetate butyrate in (a) has a rated viscosity between about 10 and 50 seconds by ASTM method D-1343-T.
Claim 3
Dependent Claim
39 words
A method according to claim 1 in which the flux promotor in (c) comprises in combination glycerol in amount from about 1.5 percent to about 6 percent and n-propanol in amount from about 4.5 percent to about 18 percent.
Claim 4
Dependent Claim
40 words
A method according to claim 1 in which the flux promoter in (c) comprises in combination glycerol in amount from about 1.5 percent to about 6 percent and lactic acid in amount From about 4.5 percent to about 18 percent.
Claim 5
Dependent Claim
15 words
A method according to claim 1 in which the organic solvent in (d) is acetone.
Claim 6
Dependent Claim
73 words
A method according to claim 1 in which the casting solution comprises: a. cellulose acetate butyrate of about 17 percent combined butyryl groups and about 29.5 percent combined acetyl groups and viscosity about 15 seconds by ASTM method D-1343-54T, in amount about 22 percent; b. Triethyl phosphate in amount about 25 percent; c. glycerol in amount about 2 percent; d. n-propanol in about 6 percent; and e. acetone in amount about 45 percent.
Claim 7
Dependent Claim
34 words
A method according to claim 1 in which a time up to about 90 seconds is allowed for removal by evaporation of part of the volatile constituents of said film before immersion in water.
Claim 8
Dependent Claim
33 words
A method according to claim 8 in which a time of about 60 seconds is allowed for removal by evaporation of part of the volatile constituents of said film before immersion in water.
Claim 9
Dependent Claim
10 words
A semipermeable membrane made by the method of claim 1.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |