FIELD: paint industry.
SUBSTANCE: invention relates to a thermosetting composition, using which it is possible to obtain paint films, which demonstrate resistance to formation of spots not only for a short period of time after application, but for which excellent resistance to staining can be expected also for longer periods, and which correspond to properties of the paint film required for the colored steel sheet, such as water resistance and bendability, and have high environmental and safety characteristics. Described is a thermosetting composition as an upper paint coating which contains, as essential components: (A) a polyester resin with a number-average molecular weight of 1,000–10,000 and a hydroxyl number of 5–200 mg KOH/g, (B) a blocked aliphatic polyisocyanate compound having reactivity with respect to hydroxyl groups of component (A), where the blocks are methyl ethyl ketone oxime and/or ε-caprolactam, and ratio of components of mixture is 0.5–2.0 equivalents of blocked isocyanate groups of component (B) relative to hydroxyl groups of component (A), (C) from 0.05 to 5 wt % tin compound, represented by following general formula (I), relative to total weight of solid components of resin (A) and (B)
,
where R1 is an organic group which has 1–24 carbon atoms and is directly bonded to the Sn atom through the C atom, R2 is an organic group, which has 1–24 carbon atoms and is directly bonded to C atom from (C=0) via atom C, (D) from 0.5 to 50 wt % organosilicate, represented by following general formula (II), and/or its condensation product relative to total weight of solid components of resin (A) and (B)
,
where R3, R4, R5 and R6 in formula can be identical or different, and each represents a hydrogen atom or an organic group with 1 to 2 carbon atoms, n equals 1. Also disclosed is a method for finishing color of metal sheets and a method of producing colored articles.
EFFECT: thermosetting compositions, when using which it is possible to obtain paint films with a balance of manufacturability and resistance to staining, and which do not produce harmful substances, such as formaldehyde, which is believed to cause sick building syndrome.
7 cl, 4 tbl
