摘要 |
An aqueous acid solution is used for treating beverage cans, in particular made of aluminium, in order to create on the cans an anti-corrosive, friction-reducing coating that allows the cans to be more easily lacquered. The solution contains 0.14 to 2.25 mmol/l of an alkyl amine oxide or alkyl ammonium salt with an alkyl residue having 8 to 22 C atoms, 0.25 to 1.5 mmol/l hydroxycarboxylic acids with 4 to 7 C atoms, complex fluorides and mineral acids, and preferably tannin. |