US3092535A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sulphite pulping process
Assignee: HOWARD SMITH PAPER MILLS Ltd
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Filing: 1960-04-27
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Granted: 1963-06-04
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Expires: 1980-04-27
Abstract
No abstract record available.
Inventors
- 👤 Ii George H Tomlinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:17
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/26; D21C3/266
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
133 words
THE METHOD OF PREPARING A CHEMICAL PULP FROM CELLULOSIC RAW MATERIAL COMPRISING IMPREGNATING THE MATERIAL WITH A MAGNESIUM BISULPHITE SOLUTION ESSENTIALLY FREE OF EXCESS SULPHUROUS ACID AND INITIALLY IN THE RANGE 2.5-5.0 PH, DIGESTING THE CELLULOSIC MATERIAL AT A TEMPERATURE BETWEEN 160 AND 200*C., FOR A PREDETERMINED DIGESTION PERIOD WHILE MAINTAINING THE PH OF THE SOLUTION AS MEASURED AT ROOM TEMPERATURE AT A VALUE BETWEEN 3.0 AND 4.0 DURING THE PERIOD WHEN THE MAJOR SULPHONATION OF THE LIGNIN AND DISSOLUTION FROM THE CELLULOSE TAKES PLACE, AND INCREASING THE PH OF THE SOLUTION TO A MAXIMUM VALUE IN THE RANGE OF 4.75-6.5 AS MEASURED AT ROOM TEMPERATURE DURING THE FINAL PORTION OF THE DIGESTION PERIOD BY THE ADDITION OF AN ALKALINE MAGNESIUM COMPOUND TO THE SOLUTION TO FORM A DEFIBRED PULP WITHOUT MECHANICAL REFINING.
Claim 2
Independent Claim
133 words
THE METHOD OF PREPARING A CHEMICAL PULP FROM CELLULOSIC RAW MATERIAL COMPRISING IMPREGNATING THE MATERIAL WITH A MAGNESIUM BISULPHITE SOLUTION ESSENTIALLY FREE OF EXCESS SULPHUROUS ACID AND INITIALLY IN THE RANGE 2.5-5.0 PH, DIGESTING THE CELLULOSIC MATERIAL AT A TEMPERATURE BETWEEN 160 AND 200*C., FOR A PREDETERMINED DIGESTION PERIOD WHILE MAINTAINING THE PH OF THE SOLUTION AS MEASURED AT ROOM TEMPERATURE AT A VALUE BETWEEN 3.0 AND 4.0 DURING THE PERIOD WHEN THE MAJOR SULPHONATION OF THE LIGNIN AND DISSOLUTION FROM THE CELLULOSE TAKES PLACE, AND INCREASING THE PH OF THE SOLUTION TO A MAXIMUM VALUE IN THE RANGE OF 4.75-6.5 AS MEASURED AT ROOM TEMPERATURE DURING THE FINAL PORTION OF THE DIGESTION PERIOD BY THE ADDITION OF AN ALKALINE MAGNESIUM COMPOUND TO THE SOLUTION TO FORM A DEFIBRED PULP WITHOUT MECHANICAL REFINING.
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) | 1966-06-03 | 1966-12-03 | 1967-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1970-06-03 | 1970-12-03 | 1971-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1974-06-03 | 1974-12-03 | 1975-06-04 | $7700.00 | Window Closed / Lapsed |