Cationic electrodeposition process

In a cationic electrodeposition for coating an electric conductive substrate as a cathode with an electrodeposition-coating composition containing a resin;

• an improvement characterized in that said resin is a resin having hydroxyl group, tertiary amino groups, quaternary ammonium groups and blocked isocyanate groups which are reactive with hydroxyl group at an elevated temperature which is obtained by reacting
• (a) a polyisocyanate;
• (b) a polyhydroxyl compound;
• (c) a hydroxyl compound having tertiary amino group;
• (d) a hydroxyl compound having quaternary ammonium group;
• and
• (e) a monofunctional blocking agent, under conditions such that hydroxyl group of (b), (c) and (d) and the blocking group of (e) react with isocyanate group of (a) and the reaction product of the isocyanate group and of (e) is not disassociated, the proportions of (c) and (d) being such that the ratio of nitrogen atoms of the quaternary ammonium groups are 0.1 to 95 mole % of total nitrogen atoms of the tertiary amino groups and quaternary ammonium groups.