Cleaning process of aluminum surfaces and refilling composition to lower the pH of the washing solution in the pre-cleaning stage of a washing process

摘要

An acidic cleaning process for aluminum, especially aluminum cans, that includes a pre-cleaning washing stage followed by an acid cleaning stage is improved by including in the pre-cleaning washing solution both of (i) a component of polyalkoxylated straight or branched chain alcohol surfactant and (ii) a component of polyalkylene glycol-abietic acid surfactant, which are maintained during the process in a ratio of component (i) to component (ii) within the range from 0.4:1 to 3.0:1. The method is particularly useful when the acid cleaning stage also contains both these types of surfactants, but at a lower ratio. A pre-cleaner replenisher composition comprising water, sulfuric acid, and polyalkoxylated straight or branched chain alcohol surfactant is advantageously used in the process.