Synergistic flame retardant compositions for polyphenylene ether resins

Claim 1

A flame retardant composition comprising a homogeneous blend of polymers containing about 10 to 90 parts by weight of polyphenylene ether resin, about 90 to 10 parts by weight of polystyrene, and a flame-retarding effective amount of a mixture of (A) a phosphine compound (I): ##STR7## wherein R 1 and R 2 are each selected from alkyl of 4 to 12 carbon atoms, cycloalkyl of 5 to 8 carbon atoms, phenyl, halophenyl containing 1 to 3 halogen atoms, omega-cyanoalkyl containing 1 to 4 carbon atoms, and benzyl; or (II): ##STR8## wherein R 3 is selected from cycloalkyl of 5 to 8 carbon atoms or omega-cyanoalkyl of 1 to 4 carbon atoms, and X is selected from (a) --CH.sub.2).sub.n wherein n is an integer from 1 to 6; (b) the group ##STR9## wherein R 4 is alkyl of 1 to 4 carbon atoms and y is an integer from 0 to 4; and (c) the group ##STR10## and (B) a phosphonate compound (III): ##STR11## wherein R 5 is selected from phenyl, benzyl, or alkylbenzyl containing 1 to 3 alkyl groups of 1 to 4 carbon atoms; or (IV): ##STR12## wherein Y is ##STR13## wherein R 6 is alkyl of 1 to 4 carbon atoms and x is an integer from 0 to 4; said mixture containing said component (A) and (B) in a weight ratio of from about 1:3 to 3:1.