US4557896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treatment of aqueous systems
Assignee: Grace Dearborn Ltd
•
Filing: 1981-06-09
•
Granted: 1985-12-10
•
Expires: 2001-06-09
Abstract
Abstract Composition and method for inhibiting corrosion in aqueous systems using synergistic combination of an inorganic nitrite and a phosphonate, e.g., 10-20 ppm sodium nitrite plus 0.5-5 ppm hydroxyethylidene diphosphonic acid.
Inventors
- 👤 Philip Brocklebank
- 👤 John J. Bennison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:11
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
91 words
Method of inhibiting corrosion in aqueous cooling systems comprising adding thereto as the sole corrosion inhibiting ingredient a mixture consisting of a water soluble inorganic nitrite and a phosphonate of the formula ##STR3## wherein m is an integer from 1 to 10, R 1 is hydrogen or alkyl of 1 to 4 carbon atoms and R 2 is hydroxyl, hydrogen or alkyl of 1 to 4 carbon atoms, said nitrite being present in an amount of 10-35 ppm and said phosphonate being present in an amount of 0.1 to 20 ppm.
Claim 2
Dependent Claim
91 words
Method of inhibiting corrosion in aqueous cooling systems comprising adding thereto as the sole corrosion inhibiting ingredient a mixture consisting of a water soluble inorganic nitrite and a phosphonate of the formula ##STR3## wherein m is an integer from 1 to 10, R 1 is hydrogen or alkyl of 1 to 4 carbon atoms and R 2 is hydroxyl, hydrogen or alkyl of 1 to 4 carbon atoms, said nitrite being present in an amount of 10-35 ppm and said phosphonate being present in an amount of 0.1 to 20 ppm.
Claim 3
Dependent Claim
19 words
Method according to claim 1 wherein the nitrite is added at 10-20 ppm and the phosphonate at 0.5-5 ppm.
Claim 4
Dependent Claim
12 words
Method according to claim 1 in which the nitrite is sodium nitrite.
Claim 5
Dependent Claim
13 words
Method according to claim 1 in which the phosphonate is hydroxyethylidene diphosphonic acid.
Claim 6
Dependent Claim
149 words
Method of inhibiting corrosion in aqueous cooling systems comprising adding thereto as the sole corrosion inhibiting ingredient a mixture consisting of a water soluble inorganic nitrite, a phosphonate of the formula ##STR4## wherein m is an integer from 1 to 10, R 1 is hydrogen or alkyl of 1 to 4 carbon atoms and R 2 is hydroxyl, hydrogen or alkyl of 1 to 4 carbon atoms, and a polymer having a molecular weight of 500-100,000 and possessing recurring units of the general formula: ##STR5## wherein R 1 represents hydrogen or alkyl of 1 to 4 carbon atoms, X represents COOH, and Z represents hydrogen or COOH; or X and Z together represent --CO--O--CO--, said nitrite being present in an amount of 10-35 ppm, said phosphonate being present in an amount of 0.1 to 20 ppm, and said polymer being present in an amount of 0.5 to 50 ppm.
Claim 7
Dependent Claim
149 words
Method of inhibiting corrosion in aqueous cooling systems comprising adding thereto as the sole corrosion inhibiting ingredient a mixture consisting of a water soluble inorganic nitrite, a phosphonate of the formula ##STR4## wherein m is an integer from 1 to 10, R 1 is hydrogen or alkyl of 1 to 4 carbon atoms and R 2 is hydroxyl, hydrogen or alkyl of 1 to 4 carbon atoms, and a polymer having a molecular weight of 500-100,000 and possessing recurring units of the general formula: ##STR5## wherein R 1 represents hydrogen or alkyl of 1 to 4 carbon atoms, X represents COOH, and Z represents hydrogen or COOH; or X and Z together represent --CO--O--CO--, said nitrite being present in an amount of 10-35 ppm, said phosphonate being present in an amount of 0.1 to 20 ppm, and said polymer being present in an amount of 0.5 to 50 ppm.
Claim 8
Dependent Claim
19 words
Method according to claim 5 in which the polymer is polymethacrylic acid having a molecular weight of about 5000.
Claim 9
Dependent Claim
19 words
Method according to claim 5 in which the polymer is polyacrylic acid having a molecular weight of about 1000.
Claim 10
Dependent Claim
14 words
Method according to claim 3 in which 2-10 ppm of the polymer is added.
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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) | 1988-12-09 | 1989-06-10 | 1989-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-09 | 1993-06-10 | 1993-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-09 | 1997-06-10 | 1997-12-10 | $7700.00 | Window Closed / Lapsed |