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Patent US3356691A successfully refreshed from Google Patents.
US3356691A
Expired / Lapsed
US
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Process for purification of benzophenone tetracarboxylic dianhydride
Assignee: General Electric Co
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Filing: 1966-04-01
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Granted: 1967-12-05
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Expires: 1986-04-01
Abstract
No abstract record available.
Inventors
- 👤 Richard F Gaertner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:11
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
107 words
A METHOD FOR CONVERTING CRUDE BPDA TO A STANDARD PURITY IN THE RANGE OF FROM 97.5% TO 98.5% AND A WHITE COLOR FOR THE PRODUCTION OF A SOLUTION OF POLYACIDAMIDE OF RELATIVELY UNIFORM INTRINSIC VISCOSITY COMPRISING THE STEPS OF: PREPARING A SLURRY OF THE CRUDE BPDA IN THE FORM OF A POWDER IN AN ALIPHATIC KHYDROCARBON ALCOHOL HAVING A BOILING POINT OF LESS THAN ABOUT 100*C., STIRRING THE SLURRY AT ROOM TEMPERATURE, FILTERING THE SLURRY TO SEPARATE THE BPDA FROM THE ALCOHOL CONTAINING DISSOLVED IMPURITIES, AND HEATIANG THE BPDA IN AN INERT ATMOSPHERE AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 75*-100*C. TO REREMOVE RESIDUAL ALCOHOL.
Claim 2
Independent Claim
107 words
A METHOD FOR CONVERTING CRUDE BPDA TO A STANDARD PURITY IN THE RANGE OF FROM 97.5% TO 98.5% AND A WHITE COLOR FOR THE PRODUCTION OF A SOLUTION OF POLYACIDAMIDE OF RELATIVELY UNIFORM INTRINSIC VISCOSITY COMPRISING THE STEPS OF: PREPARING A SLURRY OF THE CRUDE BPDA IN THE FORM OF A POWDER IN AN ALIPHATIC KHYDROCARBON ALCOHOL HAVING A BOILING POINT OF LESS THAN ABOUT 100*C., STIRRING THE SLURRY AT ROOM TEMPERATURE, FILTERING THE SLURRY TO SEPARATE THE BPDA FROM THE ALCOHOL CONTAINING DISSOLVED IMPURITIES, AND HEATIANG THE BPDA IN AN INERT ATMOSPHERE AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 75*-100*C. TO REREMOVE RESIDUAL ALCOHOL.
References Cited (Backward Citations)
US3078279A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1970-12-04 | 1971-06-05 | 1971-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1974-12-04 | 1975-06-05 | 1975-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1978-12-04 | 1979-06-05 | 1979-12-05 | $7700.00 | Window Closed / Lapsed |