VERFAHREN ZUR ABSCHEIDUNG VON ZINK IONEN VON SELBSTÄTIG ABSCHEIDBAREN ÜBERZUGSZUSAMMENSETZUNGEN

摘要

The use of selected cation exchange resins 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. Iminodiacetate cation exchange resins are very effective for removing iron ions when they are the only multivalent ions to be removed, and can be efficiently regenerated with 0.5 to 4 % by weight aqueous hydrofluoric acid. By proper choice of other cation exchange resins and operating conditions, zinc can be selectively extracted from autodeposition baths containing both iron and zinc, and either iron or zinc can be selectively displaced from the loaded ion exchange resin.