US4413117A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of polyimide powder
Assignee: BASF SE
•
Filing: 1982-06-04
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Granted: 1983-11-01
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Expires: 2002-06-04
Abstract
Abstract A polyimide powder particularly suitable for the production of moldings by high pressure sintering is prepared by mixing a solution of an aromatic polyimido-acid, obtained by a conventional process and having an intrinsic viscosity of 1.5 to 2.5 dl/g, in an aprotic dipolar organic solvent, with a water-entraining agent, heating the mixture to the boiling point of the entraining agent, azeotropically distilling off the water formed, filtering off the polyimide powder which precipitates, washing it if appropriate, and drying it.
Inventors
- 👤 Udo Reiter
- 👤 Jenoe Kovacs
- 👤 Hans-Uwe Schenck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:11
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/12; C08J3/14; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1007; C08G73/1028; C08G73/1032; C08J2379/00; C08J2379/04; C08J2379/08
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
96 words
A process for the preparation of polyimide powder which comprises: adding an inert entraining agent for water to a solution of an aromatic polyamido-acid having an intrinsic viscosity of from 1.5 to 2.5 dl/g, said polyamido-acid being dissolved in an aprotic dipolar organic solvent; heating the formed mixture to the boiling point of the entraining agent to convert the polyamido-acid to polyimide with the formation of water and to azeotropically distill off the formed water along with the entraining agent; and thereafter filtering the polyimide powder which precipitates out of the solution and drying the powder.
Claim 2
Dependent Claim
96 words
A process for the preparation of polyimide powder which comprises: adding an inert entraining agent for water to a solution of an aromatic polyamido-acid having an intrinsic viscosity of from 1.5 to 2.5 dl/g, said polyamido-acid being dissolved in an aprotic dipolar organic solvent; heating the formed mixture to the boiling point of the entraining agent to convert the polyamido-acid to polyimide with the formation of water and to azeotropically distill off the formed water along with the entraining agent; and thereafter filtering the polyimide powder which precipitates out of the solution and drying the powder.
Claim 3
Dependent Claim
26 words
The process of claim 1, wherein the aromatic polyamido-acid is a reaction product of a dianhydride of an aromatic tetracarboxylic acid with an aromatic di-primary amine.
Claim 4
Dependent Claim
16 words
The process of claim 1 or 2, wherein the entraining agent used is an aromatic hydrocarbon.
Claim 5
Dependent Claim
13 words
The process of claim 1, wherein the entraining agent is toluene or xylene.
References Cited (Backward Citations)
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US3422061A
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US3803081A
Cited
US3619329A
Cited
US3607838A
Cited
US3708459A
Cited
US4075171A
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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) | 1986-10-31 | 1987-05-02 | 1987-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-31 | 1991-05-02 | 1991-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-31 | 1995-05-02 | 1995-11-01 | $7700.00 | Window Closed / Lapsed |