Cathodic electrodeposition coating composition

A cathodic electrodeposition coating composition which comprises:

• (A) 100 parts by weight of an amine-unsaturated carboxylic acid adduct of epoxidized polybutadiene having a number average molecular weight of from 500 to 10,000 and containing from 70 to 200 mmol of a tertiary amino group, from 20 to 200 mmol of an .alpha.,.beta.-unsaturated monocarboxylate group and from 200 to 2,000 mmol of a carbon-carbon double bond, per 100 g of the resin;
• (B) from 20 to 200 parts by weight of an addition reaction product of (a) 1 mol of an epoxy resin containing at least two epoxy groups per molecule, and (b) a mixture of from 0.7 to 1.9 mol of an .alpha.,.beta.-unsaturated monocarboxylic acid and from 0.1 to 0.8 mol of an unsaturated or saturated fatty acid having at least 12 carbon atoms, provided that the total amount of the two components of the mixture is from 1.5 to 2.0 mol;
• (C) from 5 to 50 parts by weight of an addition reaction product other than (A) of (a) 1 mol of an epoxy resin containing at least two epoxy groups per molecule, and (b) a mixture of from 0.5 to 1.5 mol of an .alpha.,.beta.-unsaturated monocarboxylic acid and from 0.5 to 1.5 mol of a secondary amine, provided that the total amount of the two components of the mixture is from 1.5 to 2.0 mol;
• and
• (D) from 0 to 100 parts by weight of other water-dilutable resin.