Patent ID: 7709435
Filing Date: 2010-05-04
Classification: C11D,C23G

Abstract:
1. A method for alkaline cleaning of aluminum or aluminum alloy, characterized in that an alkaline cleaning liquid is prepared by mixing into deionized water or water which contains one or more metallic ions selected from Ca, Mg, Mn, Fe, Zn and Cu, the following ingredients (A)-(D): (A) from 0.2 to 10 g/L of one or more of organic phosphonic acid and its salts, (B) from 0.001 to 2 g/L of one or more metallic ions selected from Ca, Mg, Mn, Fe, Zn and Cu in terms of a total concentration contained in said alkaline cleaning liquid, (C) from 0.5 to 40 g/L in total of one or more alkali builders selected from alkali metal hydroxide, alkali metal carbonate, inorganic alkali metal phosphate and alkali metal silicate, and (D) from 0.1 to 10 g/L of surfactant, and is further characterized in that said alkaline cleaning liquid is brought into contact with the aluminum or aluminum alloy at a temperature of from 30° to 70° C. for 2 to 120 seconds, while maintaining a weight ratio of said organic phosphonic acid and its salts to one or more of metallic ions contained in the alkaline cleaning liquid selected from Ca, Mg, Mn, Fe, Zn and Cu within a range of from 100:0.05 to 20 and subsequently rinsing with water.