Patent US3935172A successfully refreshed from Google Patents.
US3935172A
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Regular copolyamides as desalination membranes
Assignee: United States Department of the Interior
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Filing: 1974-05-20
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Granted: 1976-01-27
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Expires: 1994-05-20
Abstract
Abstract Regular copolyamides of the formula OOOO PARALLEL PARALLEL PARALLEL PARALLEL -HN-(CH2)x-NH-C-(CH2)y-C-NH-(CH2)x-NH-C-R-C- n WHERE X IS 2 TO 10, Y IS 0 TO 8, R is a divalent aliphatic or aromatic radical having 1 to 34 carbon atoms, and n is not less than 10, are prepared by reacting an aliphatic diester with an excess of an aliphatic diamine to form a diamine diamide, and reacting the diamine diamide intermediate with an aliphatic or aromatic diacid chloride.
Inventors
- 👤 Otto F. Vogl
- 👤 Donald R. Stevenson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:08
CPC Classifications
C; C08; C08G; C08G69/00; C08G69/02; C08G69/26; C08G69/265; B; B01; B01D; B01D71/00; B01D71/06; B01D71/56; Y; Y10; Y10S; Y10S524/00; Y10S524/909; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31725
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
29 words
A film-forming copolyamide consisting essentially of the repeating units: ##EQU11## where R is selected from the group consisting of the isophthaloyl radical, the sebacyl radical and the pyridyl radical.
Claim 2
Dependent Claim
29 words
A film-forming copolyamide consisting essentially of the repeating units: ##EQU11## where R is selected from the group consisting of the isophthaloyl radical, the sebacyl radical and the pyridyl radical.
Claim 3
Dependent Claim
12 words
The copolyamide of claim 1 in which R is the isophthaloyl radical.
Claim 4
Dependent Claim
12 words
The copolyamide of claim 1 in which R is the sebacyl radical.
Claim 5
Dependent Claim
12 words
The copolyamide of claim 1 in which R is the 2,6-pyridyl radical.
Claim 6
Dependent Claim
15 words
A reverse osmosis membrane consisting essentially of a film of the copolyamide of claim 1.
Claim 7
Dependent Claim
15 words
A reverse osmosis membrane consisting essentially of a film of the copolyamide of claim 2.
Claim 8
Dependent Claim
15 words
A reverse osmosis membrane consisting essentially of a film of the copolyamide of claim 3.
Claim 9
Dependent Claim
15 words
A reverse osmosis membrane consisting essentially of a film of the copolyamide of claim 4.
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) | 1979-01-26 | 1979-07-28 | 1980-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-26 | 1983-07-28 | 1984-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-26 | 1987-07-28 | 1988-01-27 | $7700.00 | Window Closed / Lapsed |