COATING COMPOSITION HAVING SUPERIOR CORROSION-RESISTANCE AFTER BENDING AND COATED STEEL SHEET USING THE SAME

摘要

The present invention relates to an organic/inorganic composite coating composition comprising, on the solid content basis: 20-60 wt% of an urethane-acrylic resin and nanosilicate-phenoxy resin; and an inorganic anti-erosive agent. The anti-erosive agent comprises: 7-33 wt% of an epoxy-based or amino-based silane (silane A); 24-57 wt% of a vinyl-based or acrylic silane (silane B); 3-11 wt% of vanadium phosphate; 0.1-1.4 wt% of Mg oxide; 2-10 wt% of zinc phosphate; 0.5-3.4 wt% of titanium carbonate; 0.5-4 wt% of zirconium oxide; and 0.4-3 wt% of silica. When the coating composition is used to form a coating layer on a zinc-plated steel sheet, it is possible to significantly improve the erosion-resistance of the planar portion and bending processed portion of a steel sheet.