Lead-free cationic electrodeposition coating composition, electrodeposition coating process, and process for forming double layered coated film

摘要

The present invention provides a lead-free cationic electrodeposition coating composition which contains an aqueous medium, a binder resin composed of a cationic epoxy resin and a blocked isocyanate curing agent dispersed or dissolved in the aqueous medium, a neutralizing acid in order to neutralize the cationic epoxy resin, an organic solvent, and a metal catalyst, wherein the electrodeposition coating composition has a volatile organic content of 1% by weight or less, a metal ion content of 500 ppm or less, a neutralizing acid amount of 10 to 30 mg equivalent based on 100 g of binder resin solid content. The lead-free cationic electrodeposition coating composition has high throwing power, and exert a little influence on the environment due to its low VOC, low metal ion content, and reduced consumption of a coating composition itself.