US2494542A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of bleaching pulp
Assignee: Niagara Alkali Co
•
Filing: 1946-05-02
•
Granted: 1950-01-17
•
Expires: 1966-05-02
Abstract
No abstract record available.
Inventors
- 👤 Casciani Ferri
- 👤 Gordon K Storin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:26
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1057
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
118 words
A METHOD OF BLEACHING LIGNEOUS CELLULOSIC MATERIALS, WHICH COMPRISES SUBJECTING THE CELLULOSIC MATERIAL TO A PRELIMINARY BLEACHING BY TREATING WITH A BLEACHING AGENT FOR CELLULOSIC MATERIALS SELECTED FROM THE CLASS CONSISTING OF CHLORINE, HYPOCHLOROUS ACID, AND ALKALI METAL AND ALKALINE EARTH HYPOCHLORITES TO REMOVE A MAJOR PORTION OF THE NON-CELLULOSIC IMPURITIES SHORT OF THE POINT OF MATERIALLY AFFECTING THE STRENGTH OF THE CELLULOSE; TREATING SAID PRELIMINARILY BLEACHED CELLULOSIC MATERIAL WITH CHLORINE DIOXIDE TO OBTAIN AN INCREASED BRIGHTNESS, SAID BLEACHED MATERIAL HAVING POOR COLOR STABILITY; AND THEN SUBJECTING SAID BLEACHED CELLULOSIC MATERIAL TO THE ACTION OF A PEROXIDE BLEACHING AGENT WHICH DOES NOT UNDULY ATTACK THE CELLULOSIC MATERIAL AND YIELDS A FINAL BLEACHED, STRONG PRODUCT OF IMPROVED COLOR STABILITY.
Claim 2
Independent Claim
118 words
A METHOD OF BLEACHING LIGNEOUS CELLULOSIC MATERIALS, WHICH COMPRISES SUBJECTING THE CELLULOSIC MATERIAL TO A PRELIMINARY BLEACHING BY TREATING WITH A BLEACHING AGENT FOR CELLULOSIC MATERIALS SELECTED FROM THE CLASS CONSISTING OF CHLORINE, HYPOCHLOROUS ACID, AND ALKALI METAL AND ALKALINE EARTH HYPOCHLORITES TO REMOVE A MAJOR PORTION OF THE NON-CELLULOSIC IMPURITIES SHORT OF THE POINT OF MATERIALLY AFFECTING THE STRENGTH OF THE CELLULOSE; TREATING SAID PRELIMINARILY BLEACHED CELLULOSIC MATERIAL WITH CHLORINE DIOXIDE TO OBTAIN AN INCREASED BRIGHTNESS, SAID BLEACHED MATERIAL HAVING POOR COLOR STABILITY; AND THEN SUBJECTING SAID BLEACHED CELLULOSIC MATERIAL TO THE ACTION OF A PEROXIDE BLEACHING AGENT WHICH DOES NOT UNDULY ATTACK THE CELLULOSIC MATERIAL AND YIELDS A FINAL BLEACHED, STRONG PRODUCT OF IMPROVED COLOR STABILITY.
References Cited (Backward Citations)
US1580136A
Cited
US2145062A
Cited
US2100496A
Cited
US2120678A
Cited
US2129719A
Cited
US2203212A
Cited
US2344987A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-01-16 | 1953-07-18 | 1954-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-01-16 | 1957-07-18 | 1958-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-01-16 | 1961-07-18 | 1962-01-17 | $7700.00 | Window Closed / Lapsed |