To obtain a water-based coating composition satisfactory in workability and film properties upon use as a sealer in finish-coating especially a car body and excellent in hydrolysis resistance by using a 2,2-bis(hydroxymethyl)alkanoic acid having at least three carbon atoms in the main chain as a part of the polyhydric alcohol forming a polyester chain.
This composition is formed by dissolving or dispersing a component being a polyester resin containing 1-40wt.%, based on the entire reactant component forming a polyester chain, polyalkadienediol having a degree of polymerization of 5-50, a product of hydrogenation thereof or a mixture thereof and 2-50wt.% 2,2bis(hydroxymethyl)alkanoic acid having at least three carbon atoms in the main chain and having an acid value of 10-100, a hydroxyl value of 30-200 and a weight-average molecular weight of 4,000-200,000 and a component being a curing agent (e.g. melamine resin) for the resin in an aqueous medium containing a neutralizing base.
TAKAGI TAKESHI
OKUDE YOSHITAKA
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