Aqueous electrodip-lacquering coating composition and its use in coating objects

Wäßriges Elektrotauchlack-Überzugsmittel enthaltend als Bindemittel (A) 95 bis 50 Gew.% primäre und/oder sekundäre Hydroxylgruppen und primäre, sekundäre und/oder tertiäre Aminogruppen enthaltendes organisches fremdvernetzendes Kunstharz-Bindemittel und (B) 5 bis 50 Gew.% Vernetzungsmittelgemisch aus (a) blockierten Isocyanaten und (b) umesterungsfähigen Vernetzungsmitteln mit mehr als zwei Estergruppen, und (C) gegebenenfalls bis zu 30 Gew.% hydroxyfunktionelle Harze. Die Erfindung betrifft auch die Verwendung dieses Elektrotauchlack-Überzugsmittels zum Beschichten von Gegenständen, insbesondere mit elektrisch leitenden Oberflächen. 1. Aqueous electrocoating composition which comprises an organic resin binder, water-dilutable as a result of protonization by acids and containing an organic amine-containing resin component and a crosslinking agent, which composition further comprises catalysts for the thermal crosslinking and, optionally, pigments, fillers, corrosion inhibitors, conventional paint auxiliary agents and organic solvents in an amounts of up to 20% by weight based on the total weight of the composition, characterized in that the composition contains as the binder : (A) 95 to 50% by weight, based on the total amount of the binder, of an organic non-self-crosslinking resin binder with a hydroxyl value of 50 to 400, an amine value of 30 to 150 and an average molecular mass (~Mn) from about 250 to 10,000, containing primar and/or secondary hydroxyl groups and primary, secondary and/or tertiary amino groups, and (B) 5 to 50% by weight of a mixture of crosslinking agents from (a) blocked polyisocyanates and (b) crosslinking agents capable of transesterification having at least two ester groups per molecule, which are largely stable in a neutral aqueous medium and yet in a basic medium at temperatures of above 140 degrees C are capable of transamination and/or transesterification with the component (A), (a) and (b) being present in a ratio of from 1:20 to 20:1 parts by weight, and (C) optionally, up to 30% by weight based on the total weight of the components (A) and (B), of hydroxylic resins with a hydroxyl value of from 30 to 500 and an average molecular mass (~Mn) of from 300 to 5000.