BINDERS FOR CATHODIC ELECTROCOATING

摘要

O.Z. 0062/02060 Binders for cathodic electrocoating which are based on polyadducts/polycondensates which carry basic nitrogen groups and are rendered waterdilutable by protonation with an acid, and one or more crosslinking agents for these polyadducts/polycondensates, their use and electrocoating baths prepared from them. These binders essentially consist of a mixture of (A) from 50 to 90% by weight of a polyadduct/polyconden sate which carries basic nitrogen groups and is obtainable by reacting (a) an essentially epoxide-free adduct of a secondary amine and polyepoxide compound with (b) a condensate of a diamine/polyepoxide adduct which is prepared in the presence of excess diamine and separated off from excess diamine after complete conversion of the epoxide groups with one or more mono- and/or dicarboxylic acids of not less than 6 carbon atoms. (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 tempperatures with crosslinking. These binders are particularly useful for the cathodic electrocoating of electrically conductive substrates.