Inorganic hydroxides flame retardants

Inert Gas Dilution. Inert gas dilution involves the use of additives that produce large volumes of noncombustible gases when the polymer is decomposed. These gases dilute the oxygen supply to the flame or dilute the fuel concentration below the flammability limit. Metal hydroxides, metal carbonates, and some nitrogen-producing compounds function in this way as flame retardants (see Flame retardants, antimony and other inorganic compounds). 

Horn, W.E., Inorganic hydroxides and hydroxy carbonates Their function and use as flame-retardant additives, in Fire Retardancy of Polymeric Materials, Grand, A.F. and Wilkie, C.A. (Eds.), Marcel Dekker, Basel, Switzerland, 2000, Chapter 9. 

Flame-retardants are used as additives in the preparation of fire retardant paints. They are decomposed by heat to produce nonflammable components, which are able to blanket the flames. Both inorganic and organic types of flame-retardants are available in the market. The most widely used inorganic flame-retardants are aluminum trihydroxide, magnesium hydroxide, boric acid, and their derivatives. These substances have a flame-retardant action mainly because of their endothermic decomposition reaction and their dilution effect. The disadvantage of these solids is that they are effective in very high filler loads (normally above 60 percent). 

Zinc borate is an inorganic flame retardant which can be used by itself or in combination with aluminum hydroxide or magnesium hydroxide with which it forms synergistic mixtures of high performance flame retardants. It is frequently used as a surface coating on these two fillers. It reduces smoke emission and promotes char formation. 

Aluminum trihydrate, magnesium hydroxide, calcium and zinc molybdates, antimony pentoxide, and zinc borate are examples of inorganic compounds used as flame retardants in the manufacture of household furniture, upholstery, wall coverings, draperies, and carpets (National Research Council (NRC), 2000). Antimony trioxide is sometimes used in combination... 

The high flammability of isotactic polypropylene can be suppressed by incorporating magnesium hydroxide as an inorganic flame retardant filler, and poly(2,6-dimethyl-1,4-phenylene ether), which is a flame retardant polymer [75],... 

Chemically acting flame retardants work best (bromo- and chloro-organic systems in the gas phase, phosphorus and nitrogen-containing systems in the condensed phase). Physically acting inorganic flame retardants based on metal hydroxides and salts have a weaker elFect. 

Other flame retardants Inorganic phosphorus Ammonium polyphosphate Red phosphorus Melamines Melamine crystal Melamine cyanurate Melamine phosphates Magnesium hydroxide Molybdeniun compoimds Zinc borate... 

There has been growing demand for nonhalogen, low smoke polymers for wire and cable insulation and sheathing. These products can be polyolefins with nonhalogen flame retardants, often metal hydroxides. DuPont markets a maleated compatibiliser under the name Fusabond to compatibilise polyolefins with the inorganic flame retardants, ATH and magnesium hydroxide, as well as with mineral fillers like calcium carbonate. 

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