US3668138A
Expired / Lapsed
US
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Method of inhibiting corrosion with amino diphosphonates
Assignee: Calgon Corp
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Filing: 1970-11-27
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Granted: 1972-06-06
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Expires: 1990-11-27
Abstract
Abstract Amino diphosphonic acid compounds and water-soluble salts thereof alone and in combination with zinc are disclosed as inhibiting the corrosion of metals in contact with water.
Inventors
- 👤 Merwin Frederick Hoover
- 👤 Gloria Di Marco Sinkovitz
- 👤 Andrew Martin Ruland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 00:28
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
15 words
Composition of claim 1 wherein the source of zinc ion is a water-soluble zinc salt.
Claim 2
Dependent Claim
8 words
Composition of claim 1 wherein R is phenyl.
Claim 3
Dependent Claim
24 words
Composition of claim 1 wherein R is phenyl, M is selected from hydrogen and sodium, and the source of zinc ion is zinc sulfate.
Claim 4
Dependent Claim
67 words
Method of inhibiting the corrosion of metals in a water system comprising maintaining in the water of said system at least 20 ppm of an amino diphosphonate of the formula where R is selected from the group consisting of alkyl groups of one to five carbon atoms, phenyl and benzyl and where each M is independently selected from the group consisting of hydrogen, alkali metal and ammonium.
Claim 5
Dependent Claim
16 words
Method of claim 5 where R is phenyl and M is selected from hydrogen and sodium.
Claim 6
Dependent Claim
78 words
Method of inhibiting the corrosion of metals in a water system comprising maintaining in the water of said system about 3 to 100 ppm of zinc ion and about 3 to 100 ppm of an amino diphosphonate of the formula where R is selected from the group consisting of alkyl groups of one to five carbon atoms, phenyl, and benzyl and where each M is independently selected from the group consisting of hydrogen, alkali metal, zinc and ammonium.
Claim 7
Dependent Claim
24 words
Method of claim 7 where the source of zinc ion is zinc sulfate, R is phenyl, and M is selected from hydrogen and sodium.
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) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |