| 摘要 |
<p>[Problem] To provide a chromium-free undercoat paint composition giving excellent corrosion resistance at the edges, in scratched parts and in worked parts of pre-coated metal sheets. [Means of Resolution] An undercoat paint composition which is characterized in that it includes (A) bisphenol-type epoxy resin of number average molecular weight from 400 to 10, 000 or a modified form of such a resin and/or hydroxyl group-containing resin of hydroxyl group value from 5 to 200 mgKOH/g and number average molecular weight from 500 to 20,000, (B) blocked polyisocyanate compound and/or melamine resin and, with respect to the total amount of the resin solid' fractions of the (A) and (B) components, (C) from 10 to 45 mass% magnesium vanadate, (D) from 2 to 20 massl calcium ion-exchanged silica, (E)a from 10 to 45 mass% of at least one compound selected from among the group comprising zinc phosphate, zinc diphosphate, zinc dihydrogen phosphate and zinc tripolyphosphate, and (F) from 0.1 to 5 mass% of at least one compound selected from among the group comprising cerium compounds, tungstic acid compounds and molybdic acid compounds (excluding magnesium molybdate).</p> |
