Curing agent-free water based coating composition

Abstract

A water based coating composition which has excellent shelf stability and can be cured by ordinary baking in the absence of a sulfonic acid-containing acid catalyst and which gives a coating having excellent adhesion and excellent water resistance. The water based coating composition can be obtained by dissolving or dispersing 50 to 80% by weight, as a solid content, of a water-soluble polyester resin prepared by polycondensing a carboxylic acid component containing 10 to 60 mol % of a polycarboxylic acid having 3 to 4 carboxyl groups per molecule and 40 to 90 mol % of a dicarboxylic acid and 1.1 to 2.0 mol, per mole of the carboxylic acid component, of a glycol component, to obtain a polyester resin having a free carboxyl group, and dissolving the polyester resin in water in the presence of a base, 5 to 20% by weight, as a solid content, of a water based bisphenol type epoxy resin, and 15 to 45% by weight, as a solid content of an alkyl-etherified amino resin, in an aqueous medium.

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