Process for coating an electrically conductive substrate and an aqueous coating composition based on a cationic binder

Claim 1

A process for coating a substrate, comprising applying to said substrate an aqueous coating composition based on a cationic binder obtained by polymerization of a monomer mixture in the presence of 0.25-4 parts by weight of a polyethylenically unsaturated compound per 100 parts by weight of the monomer mixture, said monomer mixture consisting of (a) 1-30% by weight of a hydroxy(cyclo)alkyl (meth)acrylate of which the (cyclo)alkyl group contains 2-8 carbon atoms, (b) 4-45% by weight of an amino (meth)acrylate of the formula ##STR3## where at least one of the groups R 1 is a hydrocarbon group containing 1-12 carbon atoms and the other group R 1 is a hydrocarbon group containing 1-12 carbon atoms or a hydrogen atom, or the two groups R 1 , together with the nitrogen atom attached thereto, form a heterocyclic group, R 2 is a hydrocarbon group containing 2-12 carbon atoms and R 3 is a hydrogen atom or a methyl group, (c) 0-80% by weight of a monovinyl aromatic hydrocarbon containing 8-14 carbon atoms, and (d) 0-50% by weight of a different monoethylenically unsaturated monomer containing 2-20 carbon atoms; said polyethylenically unsaturated compound being an acrylic or methacrylic bisphenol ester of the formula H.sub.2 C=CHR--C(O)--(O--B).sub.m --[--O--D--A--D--(O--B).sub.m --].sub.n --O--C(O)--CHR=CH.sub.2 wherein R represents a hydrogen atom or a methyl group, A represents a hydrocarbon group containing 1-4 carbon atoms, B represents a hydrocarbon group containing 2-3 carbon atoms, or a 2-hydroxypropylene group D represents a phenylene group or a cyclohexylene group, m is a number from 1-4 and n is a number from 1-3; amino groups present in said binder being at least partially neutralized with an acid.