PURPOSE: To obtain a water-based coating compsn. capable of forming on a steel plate a coating film excellent in water resistance, cationic electrodeposition coatability, weldability, etc., by blending a bisphenol epoxy resin with a specific epoxy resin, silica particles, a specific org. adhesion improver and water.
CONSTITUTION: A corrosion-resistant coating compsn. comprises (a) an acrylic resin-modified epoxy resin which is obtd. by graft polymn. of a bisphenol epoxy resin with a polymerizable unsatd. monomer component contg. a carboxyl group- contg. polymerizable unsatd. monomer through the aid of a polybasic acid contg. a polymerizable unsatd. group or an acid anhydride thereof and can be diluted with water through neutralization thereof with a neutralizing agent; (b) silica particles; (c) an org. adhesion improver having in the molecule thereof a 5- or 6-membered ring structure having a nitrogen atom therein; and (d) water. The polymerizable unsatd. monomer component is desired to contain l-20wt.% polymerizable unsatd. monomer contg. an acetoacetyl group in order to improve the adhesion, corrosion resistance, boiling water resistance, alkali resistance, etc., of a coating film of the compsn.
KATO NOBUYOSHI
NAGAI YOSHINORI
TONOMURA SADAICHI
SASAKI HIROJI
OHATA TOSHIHARU
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