COATING AN IRON/ZINC SURFACE IN A BATH CONTAINING AN ORGANIC POLYMER, ACID, FLUORIDE AND AN OXIDISER; REGENERATING THE BATH WITH AN ACIDIC CATION EXCHANGE RESIN WHICH REMOVES METAL IONS; AND REGENERATING THE RESIN WITH ACID

摘要

The use of chelating type cation exchange resins, particularly those with iminodiacetic acid functionality, to remove dissolved multivalent cations such as iron, zinc, and chromium from used autodeposition compositions permits reuse of the autodeposition compositions without the need for added surfactant and without developing any undesirable graininess or other texture in the coatings formed. The cation exchange resins can be efficiently regenerated with 0.5 to 4% by weight aqueous hydrofluoric acid.