| 摘要 |
PURPOSE: A lead-free cationic electrodeposition coating composition and an electrodeposition coating method using the composition are provided, wherein the composition has a high throwing power and exerts little influence on the environment due to the low content of a volatile organic compound and a metal ion and the reduced consumption of a coating composition itself. CONSTITUTION: The lead-free cationic electrodeposition coating composition comprises an aqueous medium; a binder resin comprising a blocked isocyanate curing agent and a cationic epoxy resin dispersed or dissolved in the aqueous medium; a neutralizing acid for neutralizing the cationic epoxy resin; an organic solvent; and a metal catalyst, wherein the cationic epoxy resin has a glass transition temperature of 10-30 deg.C and a number average molecular weight of 1,500-3,000, and the amount of the neutralizing acid is 10-30 mg based on 100 g of the solid component amount of 1 wt% or less of a volatile organic material, 500 ppm or less of a metal ion and a binder resin. Preferably the cationic epoxy resin is an oxazolidone ring-containing amine modified epoxy resin; the metal ion is at least one selected from the group consisting of cerium, bismuth, copper, zinc, molybdenum and aluminium ions; and the neutralizing acid is at least one selected from the group consisting of acetic acid, lactic acid, formic acid and sulfamic acid.
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