Fire-retardant fillers smoke suppression

Atlanta, Ga., 26th-30th April 1998, p.3310-2. 012 NOVEL ZINC HYDROXYSTANNATE-COATED FILLERS AS FIRE RETARDANT AND SMOKE SUPPRESSANT ADDITIVES FOR HALOGENATED POLYMERS Hornsby P R Cusack P A... 

In this chapter, an overview is presented of the principal fire-retardant filler types, including details of their origin, characteristics, and application. Consideration will then be given to their mechanism of action both as flame retardants and as smoke suppressants, and to means for potentially increasing their efficiency using synergists and nanoscale variants. 

Bonsignore, P.V. Levendusky, T.L. Alumina trihydrate as a flame retardant and smoke suppressive filler in rigid high density polyurethane foams. J. Fire Flammability 1977, 8, 95-114. 

PVC-U formulations have low flammability due to the chlorine content. The addition of plasticiser in PVC-P formulations necessitates the use of flame retardant and smoke suppressant additives. These additives are known as functional fillers and a correct balance is necessary to achieve all the end-use specification requirements. They are predominately used in cable, conveyer belting and roofing membrane formulations to give resistance to fire initiation and propagation. It is also important to reduce dripping in a fire situation and that as little smoke as possible is generated. Antimony trioxide has been used extensively, usually in combination with phosphate ester plasticisers, giving excellent fire performance and mechanical properties. 

Consideration is given to the influence of combinations of zinc hydroxystannate (ZHS) with hydrated fillers, on the fire properties of plasticised PVC and polychloroprene. It is shown that magnesium and aluminium hydroxides specially coated with ZHS, confer significantly increased combustion resistance and lower levels of smoke evolution to these polymers. This permits large reductions to additive loading relative to unmodified filler, without sacrificing flame retardant or smoke suppressant performance. 10 refs. 

Fire retardant fillers affect smoke formation. " Table 12.5 gives some data on the specific extinction area. The data show that, with the exceptions of A1(OH)3 and Mg(OH)2, fillers have a small effect on smoke suppression. 

Aluminium trihydrate (ATH) is also known as hydrated alumina. It is the most widely used FR additive in volume terms, representing 43% of all flame-retardant chemicals in volume (but only about 29% in value). As well as flame retarding and smoke suppressing, it is an economical filler/extender. In a fire, it undergoes an endothermic dehydration with a twofold action, simultaneously absorbing... 

Cusak et al." found that zinc hydroxystannate greatly enhanced the performance of an ATH-organoclay synergistic fire retardant system in an EVA formulation that allowed reductions in the overall filler level with no or little compromise in terms of flame retardant or smoke suppressant properties. 

Smoke suppressants are also important additives in fire retardance. Visible smoke may accompany or precede the development of heat and toxic gases. It results from an incomplete combustion. Additives such as antimony oxide, metal (Ba, Ca, Zn) borates, A1(0H)3, Mg(OH)2, MgC03, and magnesium oxychloride are used as fillers and flame retardants, but they are also good smoke reducers. 

TrialkylPhosphates. Triethyl phosphate [78-40-0] C H O P, is a colorless Hquid boiling at 209—218°C containing 17 wt % phosphoms. It may be manufactured from diethyl ether and phosphoms pentoxide via a metaphosphate intermediate (63,64). Triethyl phosphate has been used commercially as an additive for polyester laminates and in ceHulosics. In polyester resins, it functions as a viscosity depressant as weH as a flame retardant. The viscosity depressant effect of triethyl phosphate in polyester resins permits high loadings of alumina trihydrate, a fire-retardant smoke-suppressant filler (65,66). 

Wan Hanafi, W.Z.A. and Hornsby, P.R., Smoke suppression and fire retardancy in unsaturated polyester compositions containing hydrated fillers, Plast. Rubber Composites Process. Appl., 19, 175-184, 1993. 

Hornsby, P.R. and Watson, C.L., Mechanistic aspects of smoke suppression and fire retardancy in polymers containing magnesium hydroxide filler, Plast. Rubber Process. Appl., 11,45-51, 1989. 

The effect of fillers on smoke suppression depends on the particle size and crystalline structure of the filler. A new fire retardant, based on a hydrated potassium-magnesium aluminosilicate, in two grades - coarse and fine is available. The fine grade is twice as effective as the coarse grade. ... 

Yersamag . [Morton Int l.] Magnesium hydroxide filler, fire retardant smoke suppressant fex plastics, thermosets, dastomers. 

Magnum-White. [RMc Minerals] Magnesium hydroxide/calcium carbonate blend fire retardant smoke suppressant filler for PVC compds., SBR-latex formulations. 

Hull, T.R. Wills, C.L. Artingstall, T. Price, D. MUnes, G.J. Mechanisms of smoke and CO suppression from EVA composites, in M. Lx Bras, C.A. Wilkie, S. Bourbigot, S. Duquesne, and C. Jama, Eds., Fire Retardancy of Polymers New Applications of Mineral Fillers. Royal Society of Chemistry, London, 2005, pp. 372-385. 

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