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An aqueous coating composition useful as electro-deposition coatings includes (A') an aqueous dispersion of a resin (A) having functional groups which are reactive toward isocyanate, and (B') an aqueous, solvent-free dispersion of a solubilized masked polyisocyanate (B). The coating is cured by baki

An aqueous coating composition useful as electro-deposition coatings includes (A') an aqueous dispersion of a resin (A) having functional groups which are reactive toward isocyanate, and (B') an aqueous, solvent-free dispersion of a solubilized masked polyisocyanate (B). The coating is cured by baking at a temperature which regenerates the isocyanate groups.

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[ What is claimed is:] [1.] A method of making an aqueous coating composition comprising:forming an aqueous dispersion (A') of an amino-epoxy resin (A) having functional groups which react with isocyanate groups, andforming an aqueous, solvent-free dispersion (B') of a solubilized masked polyisocyan

[ What is claimed is:] [1.] A method of making an aqueous coating composition comprising:forming an aqueous dispersion (A') of an amino-epoxy resin (A) having functional groups which react with isocyanate groups, andforming an aqueous, solvent-free dispersion (B') of a solubilized masked polyisocyanate (B), wherein the polyisocyanate (B) comprises a cationically solubilized masked polyisocyanate (Ba) or an anionically solubilized masked polyisocyanate (Bb),wherein the cationically solubilized masked polyisocyanates (Ba) is made by reacting in bulk or in the melt,(Ba1) a polymeric or oligomeric polyisocyanate,(Ba2) a polyhydric alcohol,(Ba3) a compound (B3c) containing at least one quaternary or sulfonium group, or tertiary amino group or phosphino group and at least one isocyanate-reactive functional group selected from the group consisting of hydroxyl, mercapto, and primary and secondary amino groups, and(Ba4) a masking compound which contains at least one active hydrogen atom and which is eliminated at baking temperatures,wherein the quantities of (Ba1) , (Ba2), (Ba3) and (Ba4) are selected such that the amine number of the product (Ba) is from 5 to 40 mg of KOH/g of solid masked polyisocyanate, and wherein the polyisocyanate (Ba1) is reacted with a less than equimolar quantity of the compounds (Ba2) and (Ba4), andcompletely or partially protonating the cationically solubilized masked polyisocyanate (Ba) by addition of an organic or inorganic acid and then dispersing it in water, thereby forming dispersion (B');and the anionically solubilized masked polyisocyanate (Bb) is obtained by reacting prior to dispersing in the aqueous, solvent-free dispersion,(Bb1) a polyisocyanate,(Bb2) a polyhydric alcohol,(Bb3) a compound (B3a) which contains at least one isocyanate-reactive functional group selected from the group consisting of hydroxyl, mercapto, and primary and secondary amino groups, and at least one acid group, and(Bb4) a masking compound which contains at least one active hydrogen atom and which is eliminated by baking temperatures, andcompletely or partially ionizing the anionically solubilized masked polyisocyanate (Bb) by addition of an organic or inorganic base and then dispersing it in water, thereby forming dispersion (B').