Patent US2581881A successfully refreshed from Google Patents.
US2581881A
Expired / Lapsed
US
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Aqueous formaldehyde distillation
Assignee: EIDP Inc
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Filing: 1948-06-11
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Granted: 1952-01-08
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Expires: 1968-06-11
Abstract
No abstract record available.
Inventors
- 👤 Pyle Cyrus
- 👤 James A Lane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:37
CPC Classifications
C; C07; C07C; C07C45/00; C07C45/78; C07C45/81; C07C45/82
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
96 words
THE METHOD OF CONCENTRATING AQUEOUS FORMALDEHYDE IN A FRACTIONATING COLUMN WHICH COMPRISES FRACTIONATING SAID AQUEOUS SOLUTION OF FORMALDEHYDE THROUGH A SUFFICIENT NUMBER OF FRACTIONATING ZONES THAT THE FORMALDEHYDE POLYMER CONTENT OF SAID SOLUTION BECOMES SO CONCENTRATED AS TO TEND TO ACCUMULATE IN SOLID FORM, AND PASSING THE CONCENTRATED LIQUID DOWNWARDLY THROUGH A SERIES OF VERTICAL ZONES DEFINED BY HORIZONTAL PERFORATED PLATES, PASSING VAPOR UPWARDLY THROUGH THE ZONES, THE ZONES BEING OF LIMITED VERTICAL EXTENT, SUCH THAT THE UPWARD PASSAGE OF GAS SPLASHES LIQUID THROUGHOUT THE ENTIRE VOLUME OF THE ZONE AND AGAINST THE CONFINING BOUNDS THEREOF.
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) | 1955-01-07 | 1955-07-09 | 1956-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1959-01-07 | 1959-07-09 | 1960-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1963-01-07 | 1963-07-09 | 1964-01-08 | $7700.00 | Window Closed / Lapsed |