Patent US2525393A successfully refreshed from Google Patents.
Patent US3754990A successfully refreshed from Google Patents.
US3754990A
Expired / Lapsed
US
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Cleaning of ferrous metal surfaces
Assignee: Dow Chemical Co
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Filing: 1971-02-22
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Granted: 1973-08-28
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Expires: 1991-02-22
Abstract
Abstract The invention is based on the discovery that upon adding a polyamine having intralinear amino groups to an aqueous alkaline solution of an ammoniated or aminated polycarboxylic acid chelating agent, a new and improved metal cleaning solution is provided. Upon bringing such cleaning solution into contact with a ferrous metal surface having hardness and/or iron oxide scale, and copper, thereon and the solution being maintained at a temperature above about 155*C. for a time sufficient to dissolve all the hardness and iron oxides, the copper is dissolved and neither precipitates from solution nor deposits on the ferrous metal surface.
Inventors
- 👤 F Teumac
- 👤 J Scruggs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:41
CPC Classifications
C; C11; C11D; C11D3/00; C11D3/16; C11D3/26; C11D3/33; C11D3/37; C11D3/3703; C11D3/3723; C11D7/00; C11D7/22; C11D7/32; C11D7/3209; C11D7/3245; C23; C23G; C23G1/00; C23G1/14; C23G1/19; C11D2111/00; C11D2111/10; C11D2111/14; C11D2111/16
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
47 words
The improvement as in claim 1 in which the aqueous cleaning solution is initially heated to a temperature in the range of above about 155* and up to 190*C, and then the temperature is reduced to about 110* to 150*C for the balance of the cleaning period.
Claim 2
Dependent Claim
67 words
The improvement as in claim 1 in which the cleaning solution contains from 0.1 to 5 per cent by weight of polyalkylenepolyamine, the cleaning solution is activated by heating to a temperature in the range of above about 155* and up to 190*C and thereafter the cleaning solution is maintained in contact with the ferrous metal surface at a temperature in the range of 110* to 150*C.
Claim 3
Dependent Claim
35 words
The improvement as in claim 1 in which the total amount of polyalkylenepolyamine added to the aqueous solution is about 2.8 parts by weight per part of copper impurity present in the system being cleaned.
References Cited (Backward Citations)
US2396938A
Cited
GB821094A
Cited
US2959555A
Cited
US3003970A
Cited
US3251778A
Cited
US3262791A
Cited
US3067070A
Cited
US3308065A
Cited
US3440170A
Cited
US3438901A
Cited
US3490741A
Cited
US3447965A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |