AQUEOUS CATHODIC ELECTRODEPOSITION LAQUER COATING COMPOSITION AND ELECTRODEPOSITION METHOD

The cathodically depositable aqueous electrocoating composition contains (A) from 95 to 5 % by weight, based on the total amount of synthetic resin binder, of one or more polycondensation, chain growth polymerisation and/or polyaddition resins, the resin or resin mixture having a) a number average molecular weight (Mn) of from 700 to 10 000, b) from 0 to 21.7 . 10 internal or terminal double bonds per 1 000 g, corresponding to a hydrogenation iodine number of from 0 to 90, c) primary hydroxyl groups corresponding to a hydroxyl number of from 15 to 300, and d) tertiary amino groups corresponding to an amine number of from 30 to 150, (B) from 5 to 95 % by weight, based on the total amount of synthetic resin binder, of chain growth polymerisation, polycondensation and/or polyaddition resins having a number average molecular weight (Mn) of from 170 to 10 000 and on average per molecule at least 2 terminal or internal ethylenic double bonds and less than one terminal ester group per molecule which is transesterifiable on baking, and is used for cathodic deposition onto electrically conducting surfaces.