Electrical insulating enamel binders having a urea and/or hydantoin structure

The present invention relates to novel binders for electrical insulating enamels, comprising at least one hydroxy- and/or amino-functional polyurethane containing urea and/or hydantoin groups, prepared by reacting: a) from 15 to 40 wt. % of an organic polyisocyanate or of a mixture of organic polyisocyanates, b) from 5 to 20 wt. % of at least one aspartic acid ester, and c) from 5 to 50 wt. % of a polyhydroxy compound having a molar weight from 62 to 3000 g/mol, in d) from 25 to 50 wt. % of a solvent or of a solvent mixture and at least one blocked isocyanate component containing ester, imide, amide, and/or urethane groups, at least one organic solvent, and optionally further auxiliary substances and additives whereby the resulting enamels being distinguished by high temperature stability and good solderability.