Patent US3236720A successfully refreshed from Google Patents.
US3236720A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for increasing flexural strength of paper
Assignee: Dow Chemical Co
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Filing: 1960-04-14
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Granted: 1966-02-22
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Expires: 1980-04-14
Abstract
No abstract record available.
Inventors
- 👤 William F Tousignant
- 👤 Henry A Huber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 09:57
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/21; D21H17/23; D21H17/33; D21H17/46; D21H17/54; D21H17/56; D21H23/00; D21H23/76; D21H23/765
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
143 words
A PROCESS COMPRISING THE STEPS OF FORMING AN AQUEOUS SLURRY OF CELLULOSE FIBERS; INCORPORATING THEREIN SUFFICIENT WASTE SULFITE LIQUOR TO PROVIDE FROM ABOUT 1 TO ABOUT 50 PERCENT BY WEIGHT OF LIGNOSULFONIC ACID AND FROM ABOUT 0.05 TO ABOUT 20 PERCENT BY WEIGHT OF A WATER-SOLUBLE POLYMERIC ALKYLENE POLYMAINE, THE WEIGHT PERCENTAGES BEING BASED ON THE WEIGHT OF THE CELLULOSE FIBERS AND THE SLURRY-MIXTURE BEING CHARACTERIZED BY A PH WITHIN THE RANGE FROM ABOUT 8 TO 10; ADJUSTING THE PH OF THE SLURRY-MIXTURE TO WITHIN THE PH RANGE FROM ABOUT 2.5 TO ABOUT 6 BY THE ADDITION OF A MINERAL ACID, WHEREBY A BINDER PRECIPITATE IS FORMED IN SITU; FORMING A WET FELTED MAT FROM THE FIBER-BINDER SLURRY THUS PREPARED; AND HEATING SUCH MAT AT A TEMPERATURE FROM ABOUT 200* TO ABOUT 450*F. FOR A PERIOD OF TIME SUFFICIENT TO CURE THE BINDER.
Claim 2
Dependent Claim
143 words
A PROCESS COMPRISING THE STEPS OF FORMING AN AQUEOUS SLURRY OF CELLULOSE FIBERS; INCORPORATING THEREIN SUFFICIENT WASTE SULFITE LIQUOR TO PROVIDE FROM ABOUT 1 TO ABOUT 50 PERCENT BY WEIGHT OF LIGNOSULFONIC ACID AND FROM ABOUT 0.05 TO ABOUT 20 PERCENT BY WEIGHT OF A WATER-SOLUBLE POLYMERIC ALKYLENE POLYMAINE, THE WEIGHT PERCENTAGES BEING BASED ON THE WEIGHT OF THE CELLULOSE FIBERS AND THE SLURRY-MIXTURE BEING CHARACTERIZED BY A PH WITHIN THE RANGE FROM ABOUT 8 TO 10; ADJUSTING THE PH OF THE SLURRY-MIXTURE TO WITHIN THE PH RANGE FROM ABOUT 2.5 TO ABOUT 6 BY THE ADDITION OF A MINERAL ACID, WHEREBY A BINDER PRECIPITATE IS FORMED IN SITU; FORMING A WET FELTED MAT FROM THE FIBER-BINDER SLURRY THUS PREPARED; AND HEATING SUCH MAT AT A TEMPERATURE FROM ABOUT 200* TO ABOUT 450*F. FOR A PERIOD OF TIME SUFFICIENT TO CURE THE BINDER.
References Cited (Backward Citations)
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US2534908A
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US2683706A
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US2846431A
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US2839417A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1969-02-21 | 1969-08-23 | 1970-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1973-02-21 | 1973-08-23 | 1974-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1977-02-21 | 1977-08-23 | 1978-02-22 | $7700.00 | Window Closed / Lapsed |