Binders for cathodic electrocoating

摘要

Binders for cathodic electrocoating which are based on polyadducts/polycondensates which carry basic nitrogen groups and are rendered water-dilutable by protonation with an acid, and one or more crosslinkng agents for these polyadducts/polycondensates, and their use. These binders essentially consist of a mixture of (A) from 50 to 90% by weight of a polyadduct/polycondensate which carries basic nitrogen groups and is obtainable by reacting (a) an adduct of a secondary amine and a polyepoxide compound, the adduct still containing free epoxide groups, with (b) a condensate which contains primary amino groups and is obtained from a primary diamine of not less than 4 carbon atoms and one or more mono- and/or dicarboxylic acids, one or more primary amino groups of the condensate (b) being used per free epoxide group of the adduct (a), and (B) from 10 to 50% by weight of a crosslinking agent which does not react with component (A) at room temperature but reacts with the latter at elevated temperatures with crosslinking. The binders are useful for the cathodic electrocoating of electrically conductive substrates and as coating materials.