Cleaning of ferrous metal surfaces |
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| 申请号 | US3754990D | 申请日 | 1971-02-22 | 公开(公告)号 | US3754990A | 公开(公告)日 | 1973-08-28 |
| 申请人 | DOW CHEMICAL CO; | 发明人 | TEUMAC F; SCRUGGS J; | ||||
| 摘要 | 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. | ||||||
| 权利要求 | 2. 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. 3. 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. 4. 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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