Antimony Pentoxide Flame Retardant Additives

Some of the useful secondary features of antimony trioxide are its good tinting strength together with the fact that it is a partial stabilizer for PVC, and presumably also for some of the halogenated co-additives such as chlorinated paraffins. Antimony trioxide is not normally a smoke suppressant, and indeed its use can sometimes lead to increased smoke evolution. CoUoidal versions of the pentoxide, Sb20s, have been marketed as additives that do act as smoke suppressants and flame retardants. Producers of antimony trioxide and pentoxide flame retardants include Anzon, Campine, Laurel, Asarco and Amspec. 

Antimony pentoxide is an alternative to antimony trioxide. It finds applications in semi-transparent materials and dark colors because of its low tinting strength. As with antimony trioxide, antimony pentoxide must be used together with halogen-containing compounds to function as a flame retardant (sec discussion under antimony trioxide). The other advantages of antimony pentoxide include its refractive index which is closer to most materials, its very small particle size, its high specific surface area, and its substantially lower density. Because of its small particle size, its is frequently used in the textile industry since its addition has only a small effect on color or on mechanical properties. Production of fine-denier fibers requires a stable dispersion and a small particle size filler. The flame retardancy of laminates is also improved with antimony pentoxide because small particles are easier to incorporate in the interfiber spaces. 

A low viscosity, preaccelerated, thixotropic flame retardant polyester (ASTM E-84, <25 flame spread - Class 1 - with 3% antimony trioxide or pentoxide, or <75 - Class 2 - without either addition), offering excellent wet-out and low drainage for use in hand-lay, spray/projection and filament winding in the manufacture of articles for the transportation, mining, electrical and building-construction industries. 

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