| 摘要 |
PROBLEM TO BE SOLVED: To provide a discoloration ionhibitor for preventing the occurrence of discoloration on the surface of metal such as a steel sheet in their washing treatment, and to provide a discoloration prevention method. SOLUTION: The discoloration ionhibitor contains at least one kind selected from carboxylic acid shown by the general formula (1) (wherein, R1 is a≤12C hydrocarbylene group; X and Y are respectively independently hydrogen, alkali metal or an amine compound; and also, any of X and Y is hydrogen) or the partial salt of carboxylic acid, and in which the pH of the aqueous solution with a concentration of 1g/L expressed in terms of the carboxylic acid concentration is <7. The discoloration ionhibitor is prepared into an aqueous solution having a concentration of 1 to 1,000 mg/L expressed in terms of the carboxylic acid concentration, and is used as water for washing to water washing treatment for metal. COPYRIGHT: (C)2006,JPO&NCIPI
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