VERFAHREN ZUR HERSTELLUNG KATHODISCH ABSCHEIDBARER BINDEMITTELDISPERSIONEN MIT VERNETZERN AUF DER BASIS VON MIT AMINOGRUPPEN VERKAPPTEN POLYISOCYANATEN.

摘要

The process concerns the prod. of aq. dispersions (I) used for the prodn. of aq. electrophoretic lacquers contg. crosslinker, which are baked for max. 30 mins at temps.below 160 deg C and contain modified epoxide-amine adducts as electrophoretic binder and amino-blocked polyisocyanates as crosslinker. (I) are produced by: 1) reacting polyepoxides and cpds. with one or more, pref. 2 OH gps. bound to aromatic and/or (cyclo)aliphatic mol. fragments per mol. at elevated temp., pref. 100-180 deg C, in the presence of catalysts, giving intermediates contg. epoxide; 2) adding a solvent (mixt.) (II), with external cooling, and boiling the resin soln. under reflux, if necessary by applying a vacuum, until the temp. of the soln. has fallen from 95 deg C to 20 deg C; 3) adding amine to the free epoxide gps. still present in the epoxide resin; and either 4a) dispersing this reaction prod. in a water-acid mixt. and adding the crosslinker (III); or 4b) adding (III) and dispersing this mixt. in a water-acid mixt. Aliphatic or aromatic polyisocyanates are used. (II) does not react with the epoxide gps. still present in the resin. In stage (2), the resin soln. is cooled to 50 deg C or over. After prodn. of the aq. dispersion (II) is removed in vacuo at temps. below 65 deg C.