Patent US4376195A successfully refreshed from Google Patents.
US4376195A
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Method of preparing high purity polyamic acids for use in electronic circuitry
Assignee: EIDP Inc
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Filing: 1982-01-07
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Granted: 1983-03-08
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Expires: 2002-01-07
Abstract
Abstract A method of increasing the yield of a high purity polyamic acid that is the reaction product of a diamino compound and a polycarboxylic acid dianhydride, comprises: 1. purifying an inert solvent by distillation or ion-exchange; 2. purifying the dianhydride by sublimation; 3. purifying the diamino compound by a slurry process that involves the repeated washing of the diamino compound first with deionized water and then methanol; and 4. reacting the purified diamino compound with the purified dianhydride in the purified inert solvent.
Inventors
- 👤 Ying K. Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:36
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1007; C08G73/1028
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
83 words
A method of increasing the yield of a high purity polyamic acid that is the reaction product of a diamino compound and a polycarboxylic acid dianhydride, comprising: a. purifying an inert solvent by distillation or ion-exchange; b. purifying the dianhydride by sublimation; c. purifying the diamino compound by a slurry process that involves the repeated washing of the diamino compound first with deionized water and then methanol; and d. reacting the purified diamino compound with the purified dianhydride in the purified inert solvent.
Claim 2
Independent Claim
83 words
A method of increasing the yield of a high purity polyamic acid that is the reaction product of a diamino compound and a polycarboxylic acid dianhydride, comprising: a. purifying an inert solvent by distillation or ion-exchange; b. purifying the dianhydride by sublimation; c. purifying the diamino compound by a slurry process that involves the repeated washing of the diamino compound first with deionized water and then methanol; and d. reacting the purified diamino compound with the purified dianhydride in the purified inert solvent.
References Cited (Backward Citations)
US4225702A
Cited
US4269968A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-03-07 | 1986-09-06 | 1987-03-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-03-07 | 1990-09-06 | 1991-03-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-03-07 | 1994-09-06 | 1995-03-08 | $7700.00 | Window Closed / Lapsed |