Binders for powder lacquers contg. amine-epoxy adduct - and epoxy resin, giving good resistance to weathering

摘要

Mixts. of (a) resinous adducts, with softening point 50 degrees C, from (i) polyamines and (ii) liquid epoxy cpds. with 1 epoxy gp., and (b) epoxy resins with softening point 70 degrees C are used as binders for powder lacquers. The powder lacquers have good stoving properties and better resistance to weathering than known epoxy resin powder lacquers. Pref. (a) (i) are (cyclo)aliphatic polyamines with is not 2 amino gps., e.g. H2N-CH2CH2-O-CH2CH2-O-CH2CH2-NH2, diethylene triamine, hexamethylene diamine (I) and triethylene tetramine; (I) or a mixt. contg. (I), e.g. with 4,4-diaminodiphenylmethane, being pref. The adduct is esp. prepd. by addn. of a liquid epoxy cpd. to the amine at 60 degrees C (80 degrees C), e.g. 90 degrees C. For good weather-resistance (ii) are pref. (cyclo)aliphatic liquid epoxy resins, esp. aliphatic polyglycidyl ethers. For priming, or where weather-resistance is less important, a liquid epoxide based on bisphenol A and epichlorohydrin, with mol. wt. 700, may be used, esp. with (I). Epoxy resins based on bisphenol A and epichlorohydrin are esp. used for (b).