US3703353A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gaseous diffusion paper deacidification
Assignee: Council On Library Resources Inc
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Filing: 1971-04-15
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Granted: 1972-11-21
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Expires: 1991-04-15
Abstract
Abstract CARRIED OUT IN A ZONE APART FROM THE IMPREGNATION ZONE AND THE HEXAMETHYLENETETRAMINE PRODUCT VAPORS THEN CONDUCTED TO THE IMPREGNATION ZONE. PAPER, FOR EXAMPLE HAVING A PH OF ABOUT 5.0 OR LOWER, IS RENDERED RESISTANT TO THE DETERIORATION THAT IS PROMOTED BY ACIDIC CONDITIONS IN PAPER BY IMPREGNATING THE PAPER, FOR EXAMPLE IN THE FORM OF A BOOK, WITH GASEOUS HEXAMETHYLENETERTRAMINE. PREFERABLY, THE HEXAMETHYLENETETRAMINE IS FORMED BY REACTING GASEOUS AMMONIA WITH GASEOUS FORMALDEHYDE, AND SUCH REACTING CAN EITHER BE EFFECTED WHILE THE REACTANTS ARE IN CONTACT WITH THE PAPER OR BE
Inventors
- 👤 James E Kusterer Jr
- 👤 John D Hind
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:29
CPC Classifications
D; D21; D21H; D21H25/00; D21H25/18
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) | 1975-11-21 | 1976-05-22 | 1976-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-21 | 1980-05-22 | 1980-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-21 | 1984-05-22 | 1984-11-21 | $7700.00 | Window Closed / Lapsed |