Process for the preparation of binder dispersions capable of being cathodically deposited using crosslinking agents based on polyisocyantes blocked by hydroxyl groups

Abstract

The invention relates to a process for the preparation of aqueous dispersions to be further processed to electrocoating paints with baking temperatures below 160.degree. C. and baking times.ltoreq.30 minutes, which dispersions contain modified epoxide-amine adducts as binders and polyisocyanates blocked by hydroxyl groups as cross-linking agents. In this process polyepoxides and compounds containing one or more, preferably 2, hydroxyl groups per molecule are reacted at elevated temperatures in the presence of catalysts to furnish epoxide-containing intermediates. A solvent or a mixture of solvents is then added with external cooling ahd the solution is boiled under reflux, if necessary in vacuo, until the temperature of the solution drops to 95.degree. C. to 20.degree. C. Amines are then added onto the epoxide groups which are still present in a free state in the epoxy resin and a dispersion is prepared by adding a water/acid mixture after adding the crosslinking agent or the dispersion is first prepared and the crosslinking agent is added subsequently.

Dependencies are inferred from the claim text.