US4566972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treatment of aqueous systems
Assignee: Veolia WTS USA Inc
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Filing: 1985-01-15
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Granted: 1986-01-28
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Expires: 2005-01-15
Abstract
Abstract A method of inhibiting and preventing scale in an aqueous system is described which comprises incorporating in the water at least one amino carboxylate having the formula: RN[--(CH.sub.2).sub.x --Z].sub.2 in which x is 1 or 2, R represents --(CH 2 ) x --Z or --CH 2 CH 2 N[--(CH 2 ) x --Z] 2 and Z represents a --COOH group, or a salt thereof, and at least one water-soluble copolymer possessing recurring units of the formula: ##STR1## wherein R 1 represents hydrogen, lower alkyl or --CH 2 COOH, R 2 represents hydrogen or lower alkyl, X represents --COOH and Z represents hydrogen or --COOH, or X and Z together represent --CO--O--CO--, and Y represents --SO 3 H, --C 6 H 5 SO 3 H (para) or --CONHQ(R 3 )(R 4 ) SO 3 H in which Q represents --CH 2 -- or --CH 2 --CH 2 -- and R 3 and R 4 independently represent hydrogen, phenyl, substituted phenyl, C 1-12 linear or branched alkyl or C 3-12 cycloalkyl, or a salt thereof.
Inventors
- 👤 John J. Bennison
- 👤 Stuart W. Longworth
- 👤 John G. Baker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 07:34
CPC Classifications
C; C02; C02F; C02F5/00; C02F5/08; C02F5/10; C02F5/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
94 words
A method of treating water in an aqueous steam generating boiler system to inhibit calcium carbonate scale formation which comprises incorporating in the water ethylenediaminetetraacetic acid or a salt thereof and a water-soluble copolymer of maleic acid and styrene sulfonic acid or a salt thereof in a weight ratio of ethylenediametetracetic acid or salt to copolymer or salt of from 50:1 to 1:10, said copolymer possessing a molecular weight of from 1,000 to less than 10,000 and maleic acid and styrene sulfonic acid recurring units in a molar proportion of about 75:25 to 5:95.
Claim 2
Independent Claim
94 words
A method of treating water in an aqueous steam generating boiler system to inhibit calcium carbonate scale formation which comprises incorporating in the water ethylenediaminetetraacetic acid or a salt thereof and a water-soluble copolymer of maleic acid and styrene sulfonic acid or a salt thereof in a weight ratio of ethylenediametetracetic acid or salt to copolymer or salt of from 50:1 to 1:10, said copolymer possessing a molecular weight of from 1,000 to less than 10,000 and maleic acid and styrene sulfonic acid recurring units in a molar proportion of about 75:25 to 5:95.
Claim 3
Dependent Claim
19 words
A method according to claim 1 in which in the copolymer the recurring units containing sulphonate are in excess.
Claim 4
Dependent Claim
27 words
A method according to claim 1 in which the weight ratio of the ethylenediaminetetraacetic acid or salt to the copolymer or salt is from 30:1 to 10:1.
Claim 5
Dependent Claim
87 words
A composition suitable for inhibition of calcium carbonate scale in an aqueous steam generating boiler system which comprises ethylenediaminetetraacetic acid or a salt thereof and a water-soluble copolymer of maleic acid and styrene sulfonic acid or a salt thereof possessing a molecular weight of from 1,000 to less than 10,000 and maleic acid and styrene sulfonic acid recurring units in a molar proportion of 75:25 to 5:95, said composition having a weight ratio of ethylenediaminetetraacetic acid or salt to copolymer or salt of from 50:1 to 1:10.
Claim 6
Dependent Claim
87 words
A composition suitable for inhibition of calcium carbonate scale in an aqueous steam generating boiler system which comprises ethylenediaminetetraacetic acid or a salt thereof and a water-soluble copolymer of maleic acid and styrene sulfonic acid or a salt thereof possessing a molecular weight of from 1,000 to less than 10,000 and maleic acid and styrene sulfonic acid recurring units in a molar proportion of 75:25 to 5:95, said composition having a weight ratio of ethylenediaminetetraacetic acid or salt to copolymer or salt of from 50:1 to 1:10.
Claim 7
Dependent Claim
26 words
A composition according to claim 4 in which the weight ratio of ethylenediaminetetraacetic acid or salt to the copolymer or salt is from 30:1 to 10:1.
Claim 8
Dependent Claim
39 words
A composition according to claim 4 which is in the form of an aqueous solution containing 5 to 60% by weight of ethylenediaminetetraacetic acid or salt thereof and 0.15 to 6% by weight of the copolymer or salt thereof.
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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) | 1989-01-27 | 1989-07-29 | 1990-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-27 | 1993-07-29 | 1994-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-27 | 1997-07-29 | 1998-01-28 | $7700.00 | Window Closed / Lapsed |