Synergism phosphorus-bromine

Tris(tribromoneopentyl) phosphate combines bromine and phosphorus in the same molecule it has been successfully incorporated into polypropylene. Studies have dealt with the question of synergism between bromine and phosphorus present in the same molecule.71,72 Fire-retardant efficiency without the need for antimony oxide opens the door for this product in the field of PP fibers and textiles. 

Phosphorus compounds should be added to an extent of 1.5 to 2 per cent of phosphorus content in the foam. Above this level, no further flammability reduction is gained. Even 1 per cent of phosphorus is satisfactory in the presence of 10 to 15 per cent of chlorine, and in fact, the phosphorus level can be decreased to 0.5 per cent at 4 to 7 per cent content of bromine. Halogen-containing polyurethane foams are preferably supplemented with antimony trioxide synergent. 

The use of phosphorus and bromine in the same molecnle as, for example, tris(2,3-dibromopropyl)phosphate is perhaps the most nsefnl approach, as it helps to get the best possible utilisation of the halogen when the flame-retardant molecule breaks down. At the same time there is strong evidence of synergism when mixtures of phosphorus and bromine componnds are nsed. 

Phosphorus compounds, e.g. ammonium polyphosphate or encapsulated red phosphorus particles were also mentioned as efficient fire retardants [105,106]. As an additive, which combines the fire retardant function of nitrogen and phosphorus and exhibits synergism of nitrogen and phosphorus, melamine diphosphate was described [107]. Bromine compounds are synergistic fire retardants, if used jointly with antimony oxide [108]. 

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