US3878037A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of enhancing the hypochlorite bleaching of pulp
Assignee: Veolia WTS USA Inc
•
Filing: 1973-06-29
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Granted: 1975-04-15
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Expires: 1993-06-29
Abstract
Abstract The present invention is directed to pulp bleaching processes, and in particular compositions for use in the bleaching process to enhance the efficiency of the process. It was discovered that if a low molecular weight water soluble polymer of acrylic acid, or water soluble salt thereof was added either alone or together with a carboxymethyl cellulose to the bleaching solution, that less bleaching solution was required.
Inventors
- 👤 Gerald D Hansen
- 👤 Elizabeth G Varney
- 👤 Philip S Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 03:00
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1026; D21C9/1036
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
77 words
A METHOD OF ENHANCING THE HYPOCHLORITE BLEACHING OF PULP WHICH COMPRISES ADDING TO THE BLEACHING MEDIUM, A WATER SOLUBLE POLYACRYLIC ACID HOMOPOLYMER OR ITS WATER SOLUBLE SALT, SAID HOMOPOLYMER HAVING A MOLECULAR WEIGHT OF FROM ABOUT 500 TO 20,000 AND CONTACTING SAID MEDIUM WITH AN AQUEOUS SLURRY OF THE PULP TO BE BLEACHED, SAID HOMOPOLYMER BEING ADDED TO THE BLEACHING MEDIUM IN AN AMOUNT OF FROM 0.5 TO 100 PARTS PER MILLION PARTS OF AQUEOUS SLURRY PULP.
Claim 2
Independent Claim
77 words
A METHOD OF ENHANCING THE HYPOCHLORITE BLEACHING OF PULP WHICH COMPRISES ADDING TO THE BLEACHING MEDIUM, A WATER SOLUBLE POLYACRYLIC ACID HOMOPOLYMER OR ITS WATER SOLUBLE SALT, SAID HOMOPOLYMER HAVING A MOLECULAR WEIGHT OF FROM ABOUT 500 TO 20,000 AND CONTACTING SAID MEDIUM WITH AN AQUEOUS SLURRY OF THE PULP TO BE BLEACHED, SAID HOMOPOLYMER BEING ADDED TO THE BLEACHING MEDIUM IN AN AMOUNT OF FROM 0.5 TO 100 PARTS PER MILLION PARTS OF AQUEOUS SLURRY PULP.
Claim 3
Dependent Claim
18 words
A method according to claim 1 wherein calcium hypochlorite or sodium hypochlorite is used to bleach the pulp.
Claim 4
Dependent Claim
19 words
A method according to claim 1 wherein a water soluble carboxymethyl cellulose is used in conjunction with the homopolymer.
Claim 5
Dependent Claim
26 words
A method according to claim 3 wherein the homopolymer and carboxymethyl cellulose are used in a weight ratio of homopolymer to cellulose of 12:1 to 1:12.
Claim 6
Dependent Claim
32 words
A method according to claim 4 wherein the combination of homopolymer and methyl cellulose are added to the pulp slurry in an amount of from about 0.5 to 100 parts per million.
Claim 7
Dependent Claim
21 words
A method according to claim 1 wherein the homopolymer of acrylic acid is sodium polyacrylate having a molecular weight of 1000.
References Cited (Backward Citations)
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US3393153A
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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) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |