US Patent 7323502 Flame retardant compositions

Organic polymeric substrates, for example polyolefins such as polypropylene, can be made flame retardant by the incorporation of a synergistic mixture of (i) at least one compound selected from the group consisting of the (a) sterically hindered nitroxyl stabilizers, (b) sterically hindered hydroxylamine stabilizers and (c) sterically hindered alkoxyamine stabilizers and (ii) at least one phosphazene flame retardant. Advantageously, a further flame retardant may be added, without the need of adding an antimony synergist. The compositions of the invention combine good flame retardant properties with light stability and good mechanical properties.