Patent US4113628A successfully refreshed from Google Patents.
US4113628A
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Asymmetric polyimide membranes
Assignee: EIDP Inc
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Filing: 1976-04-15
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Granted: 1978-09-12
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Expires: 1996-04-15
Abstract
Abstract Asymmetric polyimide membranes are prepared from tetracarboxylic acid dianhydrides and diamines. They are semipermeable and useful in the separation of different chemical species by osmosis, dialysis, electrodialysis and reverse osmosis.
Inventors
- 👤 Constance Wright Alegranti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:14
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1075; C08G73/1082; B; B01; B01D; B01D71/00; B01D71/06; B01D71/58; B01D71/62; B01D71/64; C08G73/1057; C08G73/1064; C08G73/1067; C08G73/1071; C08G73/1085
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
136 words
A microporous, opaque, asymmetric polyimide membrane not dissolving more than 10% by weight at 25° C in N,N-dimethylacetamide and consisting essentially of a polyimide having the repeating formula ##STR58## wherein R 5 is selected from the group consisting of ##STR59## and R 6 is selected from the group consisting of phenylene, tolylene, naphthylene, biphenylene, anthrylene, pyridinediyl and ##STR60## in which R 7 is selected from the group consisting of oxygen, sulfur and methylene, said membrane being shiny on one surface and dull on the other surface, and having a corrected small angle X-ray scattering pattern such that the intensity of the scattering radiation from nickel filtered CuKα radiation multiplied by the fourth power of the scattering angle (21/4) does not vary more than ± 10% for at least 0.2° within the angle range (2θ) from 0.2-0.8°.
Claim 2
Dependent Claim
136 words
A microporous, opaque, asymmetric polyimide membrane not dissolving more than 10% by weight at 25° C in N,N-dimethylacetamide and consisting essentially of a polyimide having the repeating formula ##STR58## wherein R 5 is selected from the group consisting of ##STR59## and R 6 is selected from the group consisting of phenylene, tolylene, naphthylene, biphenylene, anthrylene, pyridinediyl and ##STR60## in which R 7 is selected from the group consisting of oxygen, sulfur and methylene, said membrane being shiny on one surface and dull on the other surface, and having a corrected small angle X-ray scattering pattern such that the intensity of the scattering radiation from nickel filtered CuKα radiation multiplied by the fourth power of the scattering angle (21/4) does not vary more than ± 10% for at least 0.2° within the angle range (2θ) from 0.2-0.8°.
Claim 3
Dependent Claim
15 words
The membrane of claim 1 which is the polyimide from pyromellitic dianhydride and 4,4'-diaminodiphenyl ether.
Claim 4
Dependent Claim
16 words
The membrane of claim 1 which is the polyimide from pyrazine tetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether.
Claim 5
Dependent Claim
15 words
The membrane of claim 1 which is the polyimide from 3,4,3',4'-benzophenonetetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether.
Claim 6
Dependent Claim
16 words
The membrane of claim 1 which is the polyimide from pyromellitic dianhydride, 4,4'-diaminodiphenylbis(trifluoromethyl)methane and 4,4'-diaminodiphenyl ether.
Claim 7
Dependent Claim
12 words
The membrane of claim 1 in the form of a hollow fiber.
References Cited (Backward Citations)
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US3352388A
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US3852388A
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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) | 1981-09-11 | 1982-03-13 | 1982-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-11 | 1986-03-13 | 1986-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-11 | 1990-03-13 | 1990-09-12 | $7700.00 | Window Closed / Lapsed |