Flame retardant polyphenylene oxide thermoplastics

Claim 1

A flame retardant thermoplastic blend comprising by weight (A) 100 parts of polyphenylene oxide, (B) 20 to 300 parts of styrene resin and (C) 0.01 to 3 parts of zinc oxide per part of organothiophosphate having the formula ##STR11## which is utilized in the flame retardant thermoplastic blend in an amount of sufficient to provide from 0.5% to 5% by weight of phosphorous based on the weight of flame retardant thermoplastic blend, where R is a C.sub.(1-13) monovalent hydrocarbon radical or substituted C.sub.(1-13) monovalent hydrocarbon radical, Q is a monovalent group selected from the class consisting of ##STR12## R 1 is selected from the class consisting of divalent C.sub.(2-20) hydrocarbon radicals, halogenated divalent C.sub.(2-20) hydrocarbon radicals and divalent radicals having the formula --R.sup.2 (X).sub.a R.sup.2 -- where R 2 is a divalent C.sub.(6-13) arylene radical, X is a divalent radical selected from O, S, and C y H2 y , y is a whole number from 1 to 5 inclusive and a is 0 or 1.