Patent US4448957A successfully refreshed from Google Patents.
US4448957A
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Process for producing aromatic polyamide-imide
Assignee: Sumitomo Chemical Co Ltd
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Filing: 1983-04-13
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Granted: 1984-05-15
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Expires: 2003-04-13
Abstract
Abstract In a process for producing an aromatic polyamide-imide by polycondensation of an aromatic tricarboxylic acid and/or aromatic tricarboxylic anhydride and an aromatic diamine with heating in the presence of a dehydration catalyst, the improvement which comprises using a solvent containing sulfolane as a reaction medium.
Inventors
- 👤 Katsuji Ueno
- 👤 Kenji Nagaoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:36
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
45 words
In a process for producing an aromatic polyamide-imide by polycondensation of an aromatic tricarboxylic acid and/or aromatic tricarboxylic anhydride and an aromatic diamine by heating in the presence of a dehydration catalyst, the improvement which comprises using a solvent containing sulfolane as a reaction medium.
Claim 2
Dependent Claim
45 words
In a process for producing an aromatic polyamide-imide by polycondensation of an aromatic tricarboxylic acid and/or aromatic tricarboxylic anhydride and an aromatic diamine by heating in the presence of a dehydration catalyst, the improvement which comprises using a solvent containing sulfolane as a reaction medium.
Claim 3
Dependent Claim
18 words
A process according to claim 1, wherein the aromatic tricarboxylic acid and/or aromatic tricarboxylic anhydride is trimellitic anhydride.
Claim 4
Dependent Claim
23 words
A process according to claim 1, wherein the aromatic tricarboxylic acid and/or aromatic anhydride and the aromatic diamine are used in equimolar ratio.
Claim 5
Dependent Claim
36 words
A process according to claim 1, wherein the solvent containing sulfolane is a solvent selected from the group consisting of sulfolane, a solvent mixture of sulfolane with hydrocarbons, and a solvent mixture of sulfolane with nitrobenzene.
Claim 6
Dependent Claim
13 words
A process according to claim 4, wherein the solvent containing sulfolane is sulfolane.
Claim 7
Dependent Claim
32 words
A process according to claim 1, wherein the solvent containing sulfolane is used in a range of amount to make the concentration of the aromatic polyamide-imide formed 6 to 40% by weight.
Claim 8
Dependent Claim
19 words
A process according to claim 1, wherein the dehydration catalyst is a phosphorous acid ester and/or a boric acid.
Claim 9
Dependent Claim
13 words
A process according to claim 7, wherein the dehydration catalyst is triphenyl phosphite.
Claim 10
Dependent Claim
13 words
A process according to claim 7, wherein the dehydration catalyst is boric acid.
Claim 11
Dependent Claim
26 words
A process according to claim 1, wherein the dehydration catalyst is used in an amount of 0.1 to 20 mole % based on the aromatic diamine.
Claim 12
Dependent Claim
24 words
A process according to claim 1, wherein the reaction temperature is 160° to 300° C. and the reaction time is 2 to 10 hours.
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) | 1987-05-15 | 1987-11-14 | 1988-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-15 | 1991-11-14 | 1992-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-15 | 1995-11-14 | 1996-05-15 | $7700.00 | Window Closed / Lapsed |