Patent US1759522A successfully refreshed from Google Patents.
US4255488A
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Polyimide fibers
Assignee: I M L Corp A CORP OF DE
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Filing: 1979-07-09
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Granted: 1981-03-10
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Expires: 1999-07-09
Abstract
Abstract Polyimide fibers which have a porous, microcellular structure. Methods of making such fibers from a precursor under conditions which cause the precursor to foam and undergo imidization.
Inventors
- 👤 John Gagliani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:30
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/02; D; D01; D01D; D01D5/00; D01D5/24; D01D5/247; D01F; D01F6/00; D01F6/58; D01F6/74; C08J2379/00; C08J2379/04; C08J2379/08; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2933; Y10T428/2935; Y10T428/2973; Y10T428/2975
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
87 words
A polyimide fiber in which the polyimide is the reaction product of a diester of a benzophenonetetracarboxylic acid and at least two diamines present in an amount such that the imide forming functionalities are substantially equimolar, one of said diamines being heterocyclic and having nitrogen in the ring, another of said diamines being a para- or meta-substituted aromatic diamine which is free of aliphatic moieties, and any additional diamine being either a heterocyclic or an aromatic diamine as aforesaid, and said fiber having an expanded, microcellular structure.
Claim 2
Dependent Claim
87 words
A polyimide fiber in which the polyimide is the reaction product of a diester of a benzophenonetetracarboxylic acid and at least two diamines present in an amount such that the imide forming functionalities are substantially equimolar, one of said diamines being heterocyclic and having nitrogen in the ring, another of said diamines being a para- or meta-substituted aromatic diamine which is free of aliphatic moieties, and any additional diamine being either a heterocyclic or an aromatic diamine as aforesaid, and said fiber having an expanded, microcellular structure.
Claim 3
Dependent Claim
72 words
A polyimide fiber as defined in claim 1 in which the amines are selected from the group consisting of 3,3'-diamino diphenyl sulfone; 4,4'-diamino diphenyl sulfone; 4,4'-diamino diphenyl sulfide; 3,3'-diamino diphenyl ether; 4,4'-diamino diphenyl ether; meta-phenylene diamine; para-phenylene diamine; 2,6-diamino pyridine; and 3,5-diamino pyridine; and heterocyclic and aromatic diamines are present in a ratio of from 5-95 parts by weight of heterocyclic diamine or diamines to 95-5 parts of aromatic diamine or diamines.
Claim 4
Dependent Claim
29 words
A polyimide fiber as defined in claim 1 in which the ester is a C 1 -C 3 diester of 3,3', 4,4'-benzophenonetetracarboxylic acid or a mixture of such esters.
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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) | 1984-03-09 | 1984-09-08 | 1985-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-09 | 1988-09-08 | 1989-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-09 | 1992-09-08 | 1993-03-10 | $7700.00 | Window Closed / Lapsed |