US4167439A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Non-ionic, water-soluble polymers for improving the dry-strength of paper
Assignee: Rohm and Haas Co
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Filing: 1977-09-12
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Granted: 1979-09-11
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Expires: 1997-09-12
Abstract
Abstract A non-ionic copolymer composed of (in weight percent) 5 to 30% N-vinyl pyrrolidone, 15 to 60% acrylamide, and 30 to 70% methyl methacrylate is disclosed. The copolymer is added in minor amount to paper pulp, especially pulp containing black liquor contamination, to improve the paper making operation and the dry strength of the paper.
Inventors
- 👤 H. Scott Killam
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 05:06
CPC Classifications
C; C08; C08F; C08F220/00; C08F220/02; C08F220/10; C08F220/12; C08F220/14; C08F220/52; C08F220/54; C08F220/56; D; D21; D21H; D21H17/00; D21H17/20; D21H17/33; D21H17/34; D21H17/37; D21H17/41; D21H17/44; D21H17/45
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
92 words
A method of increasing the dry strength of paper which comprises incorporating in the pulp from which the paper is derived from about 0.15% to about 0.5% based on the dry paper fiber weight of a water-soluble non-ionic copolymer consisting essentially of polymerized units, in weight percent, of 5 to 30% N-vinyl pyrrolidone, 15 to 35% acrylamide, and 30 to 70% methyl methacrylate said copolymer having a viscosity of about 10 to about 500 centipoise at 10% by weight in water at 25° C., at a pH of about 4 to 8.
Claim 2
Independent Claim
92 words
A method of increasing the dry strength of paper which comprises incorporating in the pulp from which the paper is derived from about 0.15% to about 0.5% based on the dry paper fiber weight of a water-soluble non-ionic copolymer consisting essentially of polymerized units, in weight percent, of 5 to 30% N-vinyl pyrrolidone, 15 to 35% acrylamide, and 30 to 70% methyl methacrylate said copolymer having a viscosity of about 10 to about 500 centipoise at 10% by weight in water at 25° C., at a pH of about 4 to 8.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein the N-vinyl pyrrolidone is about 10 to 25%, and the methyl methacrylate is about 45 to 70%.
Claim 4
Dependent Claim
13 words
The method of claim 1 in which the pulp is unbleached Kraft pulp.
Claim 5
Dependent Claim
24 words
The method of claim 3 in which black liquor solids are present in an amount of up to 6% by weight of the fibers.
Claim 6
Dependent Claim
22 words
The method of claim 4 in which about 2% to 6% black liquor solids are present and 0 to about 2% alum.
Claim 7
Dependent Claim
25 words
The method according to claim 1 wherein the N-vinyl pyrrolidone is about 20%, the acrylamide is about 30% and the methyl methacrylate is about 50%.
Claim 8
Dependent Claim
30 words
The method of claim 6 wherein the incorporation is by means of an aqueous mixture containing from about 10 to about 20 weight percent of the copolymer as dispersed solids.
Claim 9
Dependent Claim
25 words
The method according to claim 1 wherein the N-vinyl pyrrolidone is about 10%, the acrylamide is about 20% and the methyl methacrylate is about 70%.
Claim 10
Dependent Claim
25 words
The method according to claim 1 wherein the N-vinyl pyrrolidone is about 5%, the acrylamide is about 25% and the methyl methacrylate is about 70%.
Claim 11
Dependent Claim
30 words
The method of claim 1 wherein the incorporation is by means of an aqueous mixture containing from about 10 to about 20 weight percent of the copolymer as dispersed solids.
Claim 12
Dependent Claim
20 words
The method of claim 1 wherein the copolymer contains up to 5% of one or more other polymerized hydrophobic monomers.
Claim 13
Dependent Claim
21 words
The method of claim 11 in which said hydrophobic monomers are one or more of butyl acrylate, ethyl methacrylate or styrene.
Claim 14
Dependent Claim
25 words
The method of claim 1 wherein the copolymer contains up to 5% of one or more polymerized hydrophilic monomers in addition to acrylamide and N-vinylpyrrolidone.
Claim 15
Dependent Claim
27 words
The method of claim 13 in which said additional hydrophilic monomers are one or more of N-methylolacrylamide, acrylic acid, vinyl acetate, methacrylamide, methacrylic acid or methyl acrylate.
Claim 16
Dependent Claim
30 words
The method of claim 2 wherein the incorporation is by means of an aqueous mixture containing from about 10 to about 20 weight percent of the copolymer as dispersed solids.
Claim 17
Dependent Claim
8 words
Paper made by the method of claim 1.
Claim 18
Dependent Claim
8 words
Paper made by the method of claim 2.
Claim 19
Dependent Claim
8 words
Paper made by the method of claim 6.
Claim 20
Dependent Claim
8 words
Paper made by the method of claim 8.
Claim 21
Dependent Claim
8 words
Paper made by the method of claim 9.
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) | 1982-09-10 | 1983-03-12 | 1983-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-10 | 1987-03-12 | 1987-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-10 | 1991-03-12 | 1991-09-11 | $7700.00 | Window Closed / Lapsed |