Self-crosslinking cationic binders and their preparation

A self-crosslinking binder, based on adducts of ammonia and epoxide compounds, for the cathodic electrocoating of metallically conductive articles, which binder has been obtained by reacting

• (A) an adduct of ammonia and epoxide compounds of the general formulae ##STR17## where R is S-alkyl of 1 to 12 carbon atoms, or phenoxy or alkylphenoxy where alkyl is of 1 to 18 carbon atoms, the E.sup.1 's are identical or different hydroxyl-containing divalent radicals and the E.sup.2 's are identical or different hydroxyl-containing trivalent or tetravalent radicals, resulting from the opening of the oxirane rings of epoxide compounds containing two, three or four epoxide groups in the molecule, an n.sup.1 is from 1 to 5, n.sup.2, n.sup.3, n.sup.4 and n.sup.6 are from 0 to 3 and n.sup.5 is from 1 to 3, with
• (B) partially or completely blocked diisocyanates or polyisocyanates, with or without
• (C) diamines or polyamines
• and subsequently protonizing the reaction product with an acid, with the proviso that for the preparation of component (A) the epoxide compounds are reacted with ammonia in such relative proportions that there are 1.75 to 10 moles of ammonia per epoxide group and the reaction product of (A) and (B) or of (A), (B) and (C) has an amine number of from 10 to 150 mg of KOH/g of solid product.