Methyl-DOPO-a new flame retardant for flexible polyurethane foam

Flexible polyurethane foams are widely used in many industrial applications, such as upholstered furniture and mattresses, automotive applications, etc. The chemical nature of the polyurethane, the low density, the high air permeability, and the open cell structure cause this material to be highly flammable. In this study, the influencing variables on the burning behavior of flexible polyurethane foams are investigated. Additionally the synthesis, formulation, characterization, and testing of a new phosphorus flame retardant (FR) methyl-DOPO 9,10-dihydro-9-oxa-methylphosphaphenthrene-10-oxide in flexible polyurethane foam with low density is performed. The new FR shows an excellent flame retarding behavior by acting mainly in the gas phase. Here the vaporization of methyl-DOPO occurs in the same temperature region as the depolymerization of the urethane and the bisubstituted urea groups during pyrolysis of the foam. Furthermore TG-MS measurements revealed the release of high concentrations of low molecular weight species like HPO, CH3PO, or PO2 in the mentioned temperature region. These species are able to scavenge the H-and OH-radicals in the radical chain reactions of the flame leading to a significant increase of the CO/CO2 ratio during cone calorimeter experiments. Copyright (C) 2010 John Wiley & Sons, Ltd.