Zinc borates as flame-retardant pigments in chlorine-containing coatings

Abstract

This paper discusses the influence of zinc borates with molecular formulas of 2ZnO·3B2O3·3.5H2O and 2ZnO·3B2O3·7.5H2O used for substituting antimony trioxide on the performance of chlorinated alkyd, flame-retardant coatings. Experimental coatings were manufactured on a laboratory scale, applied by brush on wood panels (Araucaria Angustifolia) and finally tested in a limiting oxygen chamber (LOI values), in a flame cabinet (intermittent bunsen burner rating) and in a two-foot flame tunnel (flame-spread index, panel consumption, after-flaming and after-glow). Results of laboratory tests indicated that coatings with a chlorine-containing resin used as the film-forming material, zinc borates can act as a flame retardant.