| abstract |
The present invention relates to a thermosetting composition characterized in that it contains (A) a polyester resin of number average molecular weight 1,000-10,000 and hydroxyl value 5-200 mg KOH/g and, (B) 0.5-2.0 equivalents relative to the hydroxyl groups of the aforesaid component (A) of a compound (B) which is a blocked aliphatic poly-isocyanate compound having reactivity with the hydroxyl groups of component (A), wherein the blocking is with methyl ethyl ketoxime and/or ε-caprolactam, (C) 0.05-5 parts by weight of a bismuth compound, per 100 parts by weight of total resin solids of component (A) and component (B), and (D) 0.5-50 parts by weight of an organosilicate represented by the following general formula (I) and/or a condensation product thereof, relative to 100 parts by weight of total resin solids of component (A) and component (B), wherein R 1 , R 2 , R 3 and R 4 in the formula each mean hydrogen atom or 1-10 carbon organic group, and can be the same or different, n is 1. By using the thermosetting composition, not only does the stain resistance appear a short time after painting, but also excellent stain resistance is maintained for a long period, which fulfil the paint film performance requirements for painted steel sheet such as water resistance and bending workability and which have high environmental protection qualities and safety. |