Abstract: The invention relates to a cathodic electro-dipping process wherein the electro-dipping primer employed contains a crosslinking agent which can be obtained by(I) reacting, in a first stage,(a) diphenylmethane diisocyanate and(b) a monoalcohol or a mixture of monoalcohols to give an intermediate product (A) containing isocyanate groups, and(II) reacting this intermediate product (A) in a second stage with(c) a polyol or a mixture of polyols to give an intermediate product (B) containing hydroxyl groups which(III) is reacted in a third stage either with(d) a cycloaliphatic, aliphatic or araliphatic polyisocyanate or a mixture of such polyisocyanates and(e) a monofunctional masking agent or a mixture of such masking agents or with(f) a partially-masked polyisocyanate prepared from (d) and (e)to give a crosslinking agent which is free from isocyanate groups.

Abstract: A process utilizing a pigmented aqueous basecoat composition which contains as the film-forming material a water-thinnable emulsion polymer. The water-thinnable emulsion polymer is prepared in a two-stage emulsion polymerization. In the first stage a polymer is prepared having a glass transition temperature (T.sub.G1) of +30.degree. to +110.degree. C. In the second stage a mixture of monomers is polymerized in the presence of the polymer prepared in the first stage, which mixture, polymerized on its own, would give a polymer with a glass transition temperature (T.sub.G2) of -60.degree. to +20.degree. C. The hydroxyl value of the emulsion polymer is between 2 and 100.

Abstract: The invention relates to water-dispersible binders for cationic electrocoating paints, a process for the preparation of these binders and a process for electrophoretic coating of an electrically conducting substrate, connected as cathode, from an aqueous bath based on this binder.The water-dispersible binders are reaction products of(A) epoxy resins containing low-molecular, preferably aromatic groups, having an epoxide equivalent weight below 750,(B) 10% to 60% by weight, prerferably 20% to 40% by weight, based on the total binder, of a prepolymer having a molecular weight (mass average) of 500 to 5000 and an average content per molecule of 0.1 to 1.9 hydroxyl groups and 0.1 to 1.0 carboxyl groups, the total of the hydroxyl and carboxyl groups being between 1 and 2, with an aromatic groups content of 10% to 45% by weight, calculated as phenylene groups contained in the resin solids in % by weight.

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.