Patent US4306991A successfully refreshed from Google Patents.
US4306991A
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US
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Scale inhibition
Assignee: WR Grace and Co Conn
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Filing: 1980-07-31
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Granted: 1981-12-22
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Expires: 2000-07-31
Abstract
Abstract This invention relates to an improved composition for inhibiting deposition of scale in aqueous systems. More specifically, it relates to the use of small quantities of an improved composition for preventing formation of scale and sludge deposits in steam generating boilers. The composition is characterized by the fact that by using a plurality of selected ingredients a synergistic effect is obtained. The ingredients comprise a copolymer of styrene sulfonic acid and maleic anhydride or maleic acid, along with a water soluble organophosphonic acid compound.
Inventors
- 👤 Chih M. Hwa
- 👤 Dionisio G. Cuisia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:14
CPC Classifications
C; C02; C02F; C02F5/00; C02F5/08; C02F5/10; C02F5/14
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
84 words
Composition for inhibiting scale in an aqueous system consisting essentially of (a) a member selected of the group consisting of copolymers of styrene sulfonic acid and maleic anhydride or maleic acid, and water soluble salts of said copolymers, the styrene sulfonic acid moiety in said copolymer being about 50-95 weight % and the molecular weight of the copolymers being about 1500-6000; and (b) a water soluble phosphonic acid and its water soluble salts; the weight ratio of copolymer to phosphonic acid being about 0.3-4:1.
Claim 2
Dependent Claim
84 words
Composition for inhibiting scale in an aqueous system consisting essentially of (a) a member selected of the group consisting of copolymers of styrene sulfonic acid and maleic anhydride or maleic acid, and water soluble salts of said copolymers, the styrene sulfonic acid moiety in said copolymer being about 50-95 weight % and the molecular weight of the copolymers being about 1500-6000; and (b) a water soluble phosphonic acid and its water soluble salts; the weight ratio of copolymer to phosphonic acid being about 0.3-4:1.
Claim 3
Dependent Claim
13 words
Composition according to claim in 1 in which the moiety is about 67-90%.
Claim 4
Dependent Claim
13 words
Composition according to claim 1 in which the molecular weight is about 2000-4000.
Claim 5
Dependent Claim
18 words
Composition according to claim 1 in which the weight ratio of copolymer to phosphonic acid is about 0.5-1.5:1.
Claim 6
Dependent Claim
86 words
Composition according to any one of claims 1, 2, 3, or 4 in which the phosphonic acid is selected from the group consisting of hydroxyethylidene diphosphonic acid, nitrilo tri(methylene phosphonic acid), N-carboxymethyl imino di(methylene phosphonic acid), N,N-bis(carboxymethyl) amino methylene phosphonic acid, ethylene diamine tetra(methylene phosphonic acid), hydroxypropylidene diphosphonic acid, hexamethylenediamine tetra(methylene phosphonic acid), diethylenetriamine penta(methylene phosphonic acid), aminoethylidene diphosphonic acid, n-butyl amino di(ethyl phosphonic acid), isopropyl phosphonic acid, 2-phosphono butane tricarboxylic acid-1,2,4, 2-aminoethyl phosphonic acid, sodium salt of tetraethylenepentamine hepta(methylene phosphonic acid), and methylene diphosphonic acid.
Claim 7
Dependent Claim
90 words
Composition for inhibiting scale in an aqueous system which consists essentially of (a) a member selected of the group consisting of copolymers of styrene sulfonic acid and maleic anhydride or maleic acid, and water soluble salts of said copolymers, the styrene sulfonic acid moiety in said copolymer being about 67-90% and the molecular weight of the copolymers being about 2000-4000; and (b) a member selected from a group consisting of hydroxyethylidene diphosphonic acid and its water soluble salts; the weight ratio of copolymer to hydroxyethylidene phosphonic acid being about 0.3-4:1.
Claim 8
Dependent Claim
90 words
Composition for inhibiting scale in an aqueous system which consists essentially of (a) a member selected of the group consisting of copolymers of styrene sulfonic acid and maleic anhydride or maleic acid, and water soluble salts of said copolymers, the styrene sulfonic acid moiety in said copolymer being about 67-90% and the molecular weight of the copolymers being about 2000-4000; and (b) a member selected from a group consisting of hydroxyethylidene diphosphonic acid and its water soluble salts; the weight ratio of copolymer to hydroxyethylidene phosphonic acid being about 0.3-4:1.
Claim 9
Dependent Claim
24 words
Composition according to any one of claims 1, 2, 3, 4, or 6 in which the maleic component in the copolymer is maleic anhydride.
Claim 10
Dependent Claim
24 words
Composition according to any one of claims 1, 2, 3, 4, or 6 in which the maleic component in the copolymer is maleic acid.
References Cited (Backward Citations)
US3276998A
Cited
US3072618A
Cited
US3297578A
Cited
US3289734A
Cited
US3634257A
Cited
US3630937A
Cited
US3723333A
Cited
US3650970A
Cited
US3706717A
Cited
US3671448A
Cited
US3715307A
Cited
US3890228A
Cited
BE845937A
Cited
GB1534596A
Cited
US4118318A
Cited
US4048066A
Cited
GB2023121A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-21 | 1985-06-22 | 1985-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-21 | 1989-06-22 | 1989-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-21 | 1993-06-22 | 1993-12-22 | $7700.00 | Window Closed / Lapsed |