US3754990A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cleaning of ferrous metal surfaces
Assignee: Dow Chemical Co
•
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 16:34
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.
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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) | 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 |