Patent US3988303A successfully refreshed from Google Patents.
US3988303A
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Method of preparing polyimides
Assignee: Individual
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Filing: 1974-12-23
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Granted: 1976-10-26
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Expires: 1994-12-23
Abstract
Abstract A method of preparing polyimides by polycondensation of diamines and dianhydrides of tetracarboxylic acids in the presence of a catalyst, viz. a carboxylic acid such as acetic, benzoic, a tetracarboxylic acid taken in an amount of from 0.25 to 10, preferably from 0.8 to 2.5 COOH groups per one unit of a polyimide in a polar organic solvent medium which is inert with respect to the starting diamines and dianhydrides and immiscible with water at a temperature within the range of from 100° to 220° C.
Inventors
- 👤 Vasily Vladimirovich Korshak
- 👤 Svetlana Vasilievna Vinogradova
- 👤 Yakov Semenovich Vygodsky
- 👤 Zinaida Vasilievna Geraschenko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:55
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1007; C08G73/1021
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
81 words
A method of preparing a film- and fiber-forming polyimide comprising the polycondensation of a diamine and a dianhydride of a tetracarboxylic acid in the presence of a catalyst, consisting of a carboxylic acid employed in an amount of from 0.25 to 10 COOH groups per one unit of the polyimide, in a polar organic solvent medium inert with respect to the starting diamine and dianhydride and immiscible with water, at a temperature within the range of from 100° to 220° C.
Claim 2
Independent Claim
81 words
A method of preparing a film- and fiber-forming polyimide comprising the polycondensation of a diamine and a dianhydride of a tetracarboxylic acid in the presence of a catalyst, consisting of a carboxylic acid employed in an amount of from 0.25 to 10 COOH groups per one unit of the polyimide, in a polar organic solvent medium inert with respect to the starting diamine and dianhydride and immiscible with water, at a temperature within the range of from 100° to 220° C.
Claim 3
Dependent Claim
30 words
The method of claim 1, wherein the carboxylic acid has the formula R(COOH) n , where R is an aliphatic, aromatic or heterocyclic radical; and n = 1 to 4.
Claim 4
Dependent Claim
21 words
The method of claim 1, wherein the carboxylic acid is selected from the group consisting of acetic acid and benzoic acid.
Claim 5
Dependent Claim
27 words
The method of claim 1, wherein the carboxylic acid is employed in an amount of from 0.8 to 2.5 COOH groups per one unit of the polyimide.
Claim 6
Dependent Claim
27 words
The method of claim 1, wherein the organic solvent is selected from the group consisting of nitroaromatic hydrocarbons, chlorinated aromatic hydrocarbons, chlorinated aliphatic hydrocarbons and aromatic nitriles.
Claim 7
Dependent Claim
27 words
The method of claim 1, wherein the dianhydride is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride and the polycondensation is performed at a temperature of from 120° to 140° C.
Claim 8
Dependent Claim
27 words
The method of claim 1, wherein the dianhydride is 1,4,5,8-naphthalene tetracarboxylic acid dianhydride and the polycondensation is performed at a temperature of from 190° to 220° C.
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) | 1979-10-26 | 1980-04-26 | 1980-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-26 | 1984-04-26 | 1984-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-26 | 1988-04-26 | 1988-10-26 | $7700.00 | Window Closed / Lapsed |