Patent US2644820A successfully refreshed from Google Patents.
US2644820A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inlet for
Assignee: —
•
Filing: —
•
Granted: 1953-07-07
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Expires: 1970-07-07
Abstract
No abstract record available.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:03
CPC Classifications
C; C07; C07D; C07D251/00; C07D251/02; C07D251/12; C07D251/26; C07D251/40; C07D251/54; C07D251/56; C07D251/60
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
78 words
A PROCESS FOR MINIMIZING CORROSION DIFFICULTIES IN THE PREPARATION OF MELAMINE FROM UREA WHICH COMPRISES PYROLYZING UREA AT A TEMPERATURE WITHIN THE RANGE OF FROM 275* C. TO 550* C. AND UNDER A PRESSURE IN EXCESS OF 500 ATMOSPHERES IN A REACTION VESSEL HAVING AN INNER SURFACE CONSISTING OF TRANIUM, REMOVING THE REACTION MIXTURE FROM THE REACTION VESSEL THROUGH A TITANIUMLINED LET-DOWN VALVE WHICH IS HEATED FROM AN EXTERNAL SOURCE, AND THEREAFTER SEPARATING MELAMINE FROM THE REACTION MIXTURE.
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) | 1956-07-06 | 1957-01-05 | 1957-07-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-07-06 | 1961-01-05 | 1961-07-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-07-06 | 1965-01-05 | 1965-07-07 | $7700.00 | Window Closed / Lapsed |