Organic halogen-free flame retardants

A wide variety of organic flame retardants, development speed is very fast, can be divided into halogen flame retardant and halogen-free flame retardants. The first is the use of halogen flame retardants for a class, but because of decomposition emit toxic gases, so use is very restricted. Halogen-free flame retardant halogen-free cable, flame-retardant effect, the resulting decomposition gas when heated, low smoke, low toxicity, was widely welcomed. Halogen-free flame retardants can be divided into the phosphorus-based flame retardants, nitrogen-based flame retardants and intumescent flame retardants.

Organophosphorus flame retardant is one of the most important species, flame retardant and plasticized double effect, you can make the full realization of non-halogenated flame retardant, plastic molding improve the flow properties, inhibiting residue after burning toxic and corrosive gases generated less than halogen flame retardant, flame retardant mechanism is: on the one hand retardant thermal decomposition produces acid, metaphosphoric acid, polyvinylidene acid, which contains phosphoric acid with a strong dehydration, can charring polymer surface dehydration, and elemental carbon can not happen evaporation to produce a flame burning combustion and decomposition, and therefore have a flame retardant; on the other hand retardant heat generated PO • radicals, can be a lot to absorb H • HO • radicals, thereby interrupt the combustion reaction. Organic phosphorus flame retardant mainly phosphates, phosphonates, and phosphine oxides and heterocyclic like.

Phosphate flame retardants are flame retardant. Because of its rich resources, cheap, widely used. Phosphate from the corresponding alcohols or phenols with phosphorus trichloride and hydrolysis. The market has been developed and large-scale use of phosphate ester flame retardants, tricresyl phosphate, triphenyl phosphate, tris cumyl ester, tributyl phosphate, trioctyl phosphate, cresyl diphenyl phosphate, etc. . Phosphate variety, versatile, but most phosphate products for liquid, heat resistance is poor, and the volatility is large, and the compatibility of the polymer is not ideal. For this purpose, at home and abroad to develop a number of new phosphate flame retardants, such as the US Grent Lake developed three (1-oxo-2,6,7-trimethyl-1-phospha miscellaneous oxabicyclo [2,2 2] octane-4-methyl) phosphite (Trimer) and 1-oxo-4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo azabicyclo [2.2.2] octane (PEPA). Trimer is characterized by symmetrical structure, the phosphorus content of up to 21.1%, phosphorus content of PEPA was 17.2%. Both phosphate flame retardants as a white powder. Thermal stability is very good, and the polymer has good compatibility.

Phosphonate flame retardant is a very promising development, because of the presence of CP bond phosphonate molecules, so its stability is very good, very good water resistance, solvent resistance. Phosphonate products abroad Giba-Geigy company developed Pyrovatex for N- hydroxymethyl propionamides methyl phosphonate, Mobil Antiblaze company developed for ring phosphonate. Domestic also phosphonite studied, phosphonates have synthesized N, N- p-phenylene diamine (2-hydroxyethyl) dibenzyl phosphonic acid tetraethyl ester, dimethyl methylphosphonate (DMMP) which DMMP in recent years developed an additive flame retardant. DMMP is trimethyl phosphinate as raw material in the isomerization catalyst, obtained through molecular rearrangement. The most notable feature of DMMP is up to 25% phosphorus flame retardant effect is very good, you can play the same effect when half the usual dosage flame retardants.