Zinc Stannates as Alternative Synergists in Selected Flame Retardant Systems

Zinc stannates, including zinc hydroxystannate, are used components within synergistic fire retardant systems usually in conjunction with halogenated species in a number of polymers. Their behavior is similar to antimony III oxide (ATO) in that they enhance the effectiveness of the halogenated and, principally brominated retardant (Br-FR), present. Unlike antimony III oxide, they are non-toxic but are specific in their synergistic activity. Furthermore, they are effective smoke suppressants. This article reviews the published literature with regard to this synergistic specificity as well as the role of zinc stannates as synergists and smoke suppressants in halogenated polymers exemplified by poly(vinyl chloride), polyolefins exemplified by polypropylene, polyamides, acrylonitrile-butadiene-styrene and polyester and epoxy resins.