Hardening components for paint binders

A water-dilutable cationic paint binder comprising (a) from 60 to 85% by weight of a synthetic resin which will undergo neutralization with an acid, contains functional groups which are esterifiable or capable of amidification and which is water dilutable after at least partial neutralization with an acid, and (b) from 15 to 40% by weight of a hardener compound which crosslinks at elevated temperature with said functional groups of (a) through esterification or amidification and which comprises

• (A) a KNOEVENAGEL (COPE) reaction product at an elevated temperature of a carbonyl compound and a compound of the general formula
• X--CH.sub.2 --Y
• wherein
• X is--COOR, --CN or --COCH.sub.3,
• Y is --COOR, and
• R is an alkyl radical having from 1-4 C-atoms, reacted at an elevated temperature in a MICHAEL-addition reaction with
• (B) a substituted oxazolidine carrying a secondary amino group and having the general formula ##STR6## wherein R.sub.1 is a straight chain, branched chain, or cyclic alkylene radical having from 2-12 C-atoms or an aralkylene radical,
• R.sub.2 is a hydrogen atom or a methyl group,
• R.sub.3 is a hydrogen atom or an alkyl radical,
• R.sub.4 is the radical of an acrylic or methacrylic monomer, monofunctional with regard to reaction with a double bond and remaining after reaction with an active hydrogen atom, and
• R.sub.5 is a hydrogen atom or an alkyl radical having from 1-12 C-atoms or an aryl radical,
• and said reaction product of (A) and (B) thereafter reacted at elevated temperature through the active methylene groups with
• (C) a polyisocyanate, the quantity of isocyanate groups being chosen to correspond to the active methylene groups of the oxazolidine rings.