Patent US2539558A successfully refreshed from Google Patents.
US2539558A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Permanent paper and method of making same
Assignee: Wyeth Holdings LLC
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Filing: 1948-09-28
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Granted: 1951-01-30
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Expires: 1968-09-28
Abstract
No abstract record available.
Inventors
- 👤 Studeny John
- 👤 John D Pollard
- 👤 Chester G Landes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:07
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/03; D21H17/05; D21H17/07
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
25 words
A METHOD OF IMPROVING THE STABILITY OF PAPER AGAINST AGING WHICH COMPRISES IMPREGNATING SAID PAPER WITH AN AQUEOUS SOLUTION OF A COMPOUND OF THE FORMULA
References Cited (Backward Citations)
US2247353A
Cited
US2342785A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1954-01-29 | 1954-07-31 | 1955-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-01-29 | 1958-07-31 | 1959-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-01-29 | 1962-07-31 | 1963-01-30 | $7700.00 | Window Closed / Lapsed |