US3989586A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Absorbent paper products and method of preparation
Assignee: Dow Chemical Co
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Filing: 1975-04-18
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Granted: 1976-11-02
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Expires: 1995-04-18
Abstract
Abstract Lightly cross-linked, water-insoluble copolymers of maleic anhydride with suitable vinyl monomers are dispersed with the aid of a surfactant in a cellulosic pulp slurry or papermaking furnish to prepare molded pulp or paper products incorporating said copolymer in finely divided form. The resulting product is treated with an alkaline agent such as ammonia gas or an alcoholic solution of an alkali metal hydroxide to convert the copolymer to a water-swellable salt form whereby the treated molded pulp or paper product has a high absorbency for aqueous fluids.
Inventors
- 👤 Robert N. Bashaw
- 👤 Bobby L. Atkins
- 👤 James R. Gross
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:40
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/33; D21H17/34; D21H17/41; D21H17/42; D21H17/43
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
144 words
A method for producing a sorptive paper product containing a water-insoluble, water-swellable copolymer which comprises the steps of forming a dispersion of a finely divided copolymer of maleic anhydride with styrene, ethylene, propylene, butylene or isobutylene, cross-linked with from about 0.001 to about 0.05 mole of a polyunsaturated cross-linking agent per mole of maleic anhydride in the copolymer, in an aqueous solution of a synthetic surfactant, incorporating said dispersion in an aqueous suspension of cellulosic pulp to provide from about 3 to about 25 percent by weight of said copolymer based on the weight of cellulosic material in the suspension, forming a paper product from the resulting mixed suspension, drying said product and exposing the dried product to the action of ammonia or an alcoholic solution of an alkali metal hydroxide for a predetermined period to convert the copolymer to the water-swellable salt form.
Claim 2
Independent Claim
144 words
A method for producing a sorptive paper product containing a water-insoluble, water-swellable copolymer which comprises the steps of forming a dispersion of a finely divided copolymer of maleic anhydride with styrene, ethylene, propylene, butylene or isobutylene, cross-linked with from about 0.001 to about 0.05 mole of a polyunsaturated cross-linking agent per mole of maleic anhydride in the copolymer, in an aqueous solution of a synthetic surfactant, incorporating said dispersion in an aqueous suspension of cellulosic pulp to provide from about 3 to about 25 percent by weight of said copolymer based on the weight of cellulosic material in the suspension, forming a paper product from the resulting mixed suspension, drying said product and exposing the dried product to the action of ammonia or an alcoholic solution of an alkali metal hydroxide for a predetermined period to convert the copolymer to the water-swellable salt form.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein the copolymer consists of substantially equimolar proportions of styrene and maleic anhydride.
Claim 4
Dependent Claim
11 words
The method of claim 2 wherein the cross-linking agent is divinylbenzene.
Claim 5
Dependent Claim
25 words
The method of claim 3 wherein the paper product is exposed to the action of ammonia to convert the copolymer to the ammonium salt form.
Claim 6
Dependent Claim
28 words
The method of claim 3 wherein the paper product is exposed to the action of alcoholic sodium hydroxide solution to convert the copolymer to the sodium salt form.
Claim 7
Dependent Claim
18 words
The method of claim 1 wherein the copolymer consists of substantially equimolar proportions of isobutylene and maleic anhydride.
Claim 8
Dependent Claim
11 words
The method of claim 6 wherein the cross-linking agent is N,N'-methylenebisacrylamide.
Claim 9
Dependent Claim
25 words
The method of claim 7 wherein the paper product is exposed to the action of ammonia to convert the copolymer to the ammonium salt form.
Claim 10
Dependent Claim
28 words
The method of claim 7 wherein the paper product is exposed to the action of alcoholic sodium hydroxide solution to convert the copolymer to the sodium salt form.
Claim 11
Dependent Claim
11 words
A sorptive paper product prepared by the method of claim 1.
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) | 1979-11-02 | 1980-05-03 | 1980-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-02 | 1984-05-03 | 1984-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-02 | 1988-05-03 | 1988-11-02 | $7700.00 | Window Closed / Lapsed |