Process for the production of oxalate coatings on metals and solutions therefor

摘要

A solution for producing oxalate coatings on iron, steel or aluminium bases comprises oxalic acid, polyvinyl phosphonic acid and/or a water soluble copolymer of an alkene phosphonic acid with a mono- or poly-unsaturated organic compound e.g. acrylic acid, methacrylic acid or an ester amide or nitrile thereof, a vinyl ester, maleic anhydride or crotonic acid, at least one oxidizing acceleration, a conditioning agent (an iron salt or potassium tri oxalato chromium (III) and, if desired, a phosphate or an acetate as an activator. The polymer concentration may be 0.3-17 (preferably 0.7-12) grammes per litre. The solution may be applied by dipping, flooding or spraying followed by rinsing with water and drying with hot air.