Fremgangsmåde til forhindring eller reduktion af en efter indbrænding optrædende misfarvning ved lakfilm

The invention relates to a process for preventing or reducing the discoloration after stoving of enamel coatings produced by the cathodic separation of aqueous electro-dip enamels polluted with iron ions and containing as the binder: A-1 at least one cationic amine-modified epoxy resin containing active hydrogen atoms; or A-2 at least one cationic polyacrylate resin containing active hydrogen atoms; and, as the cross-linking agent: B at least one aliphatic or cycloaliphatic blocked polyisocyanate present as part of the amine-modified epoxy resin or part of the cationic polyacrylate resin or as a separate component. In the process, an ester of 3-(3,5-di-tert.butyl-4-hydroxy-phenyl) propionic acid and a polyalcohol is incorporated into the electro-dip enamels.