Patent ID: 7947764

Claim:
A cationic electrodeposition coating composition comprising a conductive filler dispersion paste, base resin and a curing agent, said paste being formed by mixing a conductive filler (A) which is composed of Ketjen Black (a 1 ), furnace black (a 2 ), a pigment-dispersing resin (B) and a pigment-dispersing resin (C) to form a dispersion; (i) the coating composition containing 30-100 wt parts of a conductive filler (A) which contains at least 2 wt parts of Ketjen Black (a 1 ), per 100 wt parts of combined solid content of the base resin and the curing agent; (ii) the weight ratio of the furnace black (a 2 )/ Ketjen Black(a 1 ) being within a range of 5-16; (iii) the pigment-dispersing resin (B) being acrylic resin-derived pigment-dispersing resin formed by copolymerization of (meth)acrylic monomer (b 1 ) which is modified with mono- or poly-alkylene glycol or a monoether derivative thereof; nitrogen-containing, radical-polymerizable unsaturated monomer (b 2 ) which comprises unsaturated monomer (b 2 -1) having nitrogen-containing heterocycle; and other radical-polymerizable unsaturated monomer (b 3 ); (iv) the pigment-dispersing resin (C) being an onium salt type pigment-dispersing resin; (v) the coating composition being capable of forming a coating film having an electric resistance not higher than 50Ω; and (vi) the coating composition containing the onium salt-type pigment-dispersing resin (C) within a range as resin (B)/resin (C) of 10/90-90/10 in wt parts, based on 100 wt parts of the combined solid content of the acrylic resin-type pigment-dispersing resin (B) and the onium salt-type pigment-dispersing resin (C).