US3636030A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recovery of aromatic dhsocyanates from still residues
Assignee: EIDP Inc
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Filing: 1968-12-16
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Granted: 1972-01-18
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Expires: 1988-12-16
Abstract
Abstract A PROCESS FOR RECOVERING AROMATIC DIISOCYANATE VALUES FROM DISTILLATION RESIDUES OBTAINED IN THE MANUFACTURE OF AROMATIC DIISOCYANATES, SAID PROCESS COMPRISING THE STEPS OF (1) ADDING A SOLUTION OF THE STILL RESIDUES, IN AN INERT ORGANIC SOLVENT SUCH AS ORTHODICHLOROBENZENE, TO AQUEOUS HYDROCHLORIC OR HYDROBROMIC ACID AT ABOUT 25 TO 150*C. SO THAT ISOCYANATES, BIURETS AND CARBODIMIDES PRESENT IN SAID RESIDUES ARE AT LEAST PARTIALLY HYDROLYZED, (2) PHOSGENATING THE RESULTING MIXTURE AT ABOUT 150 TO 200*C. IN THE PRESENCE OF LESS THAN 10% BY WEIGHT OF WATER BASED ON THE WEIGHT OF STILL RESIDUES AND (3) RECOVERING AROMATIC DIISOCYANATE FROM THE PHOSGENATED MIXTURE.
Inventors
- 👤 Gilbert T Perkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:04
CPC Classifications
C; C07; C07C; C07C263/00; C07C263/18; C07C263/20
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |