US3617440A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for promoting the drainage from a water-pulp medium using the reaction product of a polyethylenimine having a molecular weight of at least 300 with a urea
Assignee: Dow Chemical Co
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Filing: 1968-06-17
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Granted: 1971-11-02
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Expires: 1988-06-17
Abstract
Abstract Accelerated drainage of the aqueous medium from pulp during paper manufacture is achieved by the addition of a small amount of the reaction product of polyethylenimine having a molecular weight of at least 300 and a urea. Addition of this product also imparts wet and dry strength to the paper.
Inventors
- 👤 Greene W Strother Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:14
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/02; C08G73/0206; C08G73/0213; D; D21; D21H; D21H17/00; D21H17/20; D21H17/33; D21H17/46; D21H17/54; D21H17/56
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
19 words
A process as defined in claim 1 wherein the polyethylenimine has an average molecular weight between 300 and 60,000.
Claim 2
Dependent Claim
12 words
A process as defined in claim 1 wherein each R is H.
Claim 3
Dependent Claim
29 words
A process as defined in claim 1 wherein a molar excess of amine groups in polyethylenimine to amide groups in the urea is used to form the reaction product.
Claim 4
Dependent Claim
34 words
A process as defined in claim 1 wherein a ratio of at least 1:1 of amine groups in polyethylenimine to amide groups in the urea is used to form the polyethylenimine and urea product.
Claim 5
Dependent Claim
19 words
A process as defined in claim 1 wherein the pH of said water-pulp medium is between 3.0 and 7.5.
Claim 6
Dependent Claim
15 words
A process as defined in claim 6 wherein the pH is between 4 and 6.
Claim 7
Dependent Claim
29 words
A process as defined in claim 1 wherein the concentration of reaction product within the water-pulp medium is between 0.01 and 1 percent, by weight, based on dry pulp.
Claim 8
Dependent Claim
19 words
The process as defined in claim 2 wherein the polyethylenimine has an average molecular weight between 600 and 60,000.
Claim 9
Dependent Claim
31 words
The process defined in claim 4 wherein the average molecular weight of said polyethylenimine is between 600 and 60,000 and the pH of said water-pulp medium is between 4 and 6.
References Cited (Backward Citations)
BE622590A
Cited
US3345253A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |