Patent ID: 7199184

Claim:
A process for manufacturing aqueous stoving enamels characterised in that in a first stage a polyester containing hydroxyl groups is prepared which is mixed in the second stage with a compound which has at least two groups reactive towards isocyanate and at least one anionogenic group, and this mixture is reacted with an excess of multifunctional isocyanates, and in the third stage the isocyanate-functional product of the second stage is reacted with a compound which has at least one sulfonic acid group or a sulfuric acid semi-ester group and at least one group reactive towards isocyanates, under consumption of the isocyanate groups, and subsequently the resin A obtained is neutralized and dispersed in water, whereupon a highly etherified aminoplast hardener having an average degree of polymerization of at most 1.3 is emulsified in the said mixture of resin A and water such that the aqueous system made of resin A and aminoplast hardener B in water comprises only emulsified droplets which contain at least a mass fraction of 5 % of resin A.