Electrodeposition coating composition

摘要

According to the present invention, provided is an electrodeposition coating composition, which can form an electrodeposition coating film having excellent corrosion resistance and coating film smoothness.;The present invention relates to an electrodeposition coating composition comprising a soluble metal compound (A), amine-modified resin (B) and curing agent (C), wherein the resin (B) has an average molecular weight of 1,000 to 5,000, an amine value of 20 to 100 mgKOH/g and a hydroxyl value of 50 to 400 mgKOH/g, a theoretical residual hydroxyl value when the resin (B) and curing agent are reacted in an electrodeposition coating film is from 30 to 350 mgKOH/g, and the ratio (R) of the concentration of the theoretical residual hydroxyl value to the concentration of the compound (A) in the composition, based on the total of the solid content of the resin (B) and the curing agent in the composition satisfies the relationship (4,000

主权项

1. An electrodeposition coating composition comprising
a soluble metal compound (A) containing at least one metal selected from the group consisting of Ti, Bi, Zn, Y, Nd, La and Zr, an amine-modified resin (B), and a curing agent (C),
wherein the amine-modified resin (B) has a number average molecular weight of 1,000 to 5,000, an amine value of 20 to 100 mgKOH/g and a hydroxyl value of 50 to 400 mgKOH/g,wherein the curing agent (C) is a blocked isocyanate curing agent,wherein a theoretical residual hydroxyl value when the amine-modified resin (B) and the blocked isocyanate curing agent are reacted in an electrodeposition coating film during thermal curing is within the range of 20 to 350 mgKOH/g, andwherein a ratio (R) is greater than 4,000 and smaller than 400,000,
wherein R is represented by the following formula:R=(TH)[(A)/(B+C)] wherein TH is theoretical residual hydroxyl value [mgKOH/g] and the [(A)/(B+C)] is the concentration in metal element conversion of the soluble metal compound (A) in the electrodeposition coating composition [% by mass], based on the total of a solid concentration [% by mass] of the amine-modified resin (B) and a solid concentration [% by mass] of the blocked isocyanate curing agent in the electrodeposition coating composition,and
wherein the theoretical residual hydroxyl value is a hydroxyl value derived from the amine-modified resin (B) remaining in the eletrodeposition coating film after the reaction of the amine-modified resin (B) with the blocked isocyanate curing agent, when cured by heating the electrodeposition coating film formed by electrodeposition coating.