Dopo-based hybrid flame retardants

Abstract

The invention relates to novel and improved halogen-free flame retardant compounds having the structure of Formula (I): wherein: Rand Rare independently hydrogen, C-Calkyl, —P(O)(OR), —P(O)ORR, or —P(O)R, wherein Rand Rare independently C-Calkyl, C-Caryl, C-Caralkyl or C-Calkaryl; or Rand Rtaken together form an unsaturated cyclic ring, which is optionally substituted by an alkyl group; each k is independently an integer from 1 to 2; each X is independently oxygen (O) or sulphur (S); v is 0 or 1; each Y is independently C-Calkylene, Carylene, C-Caralkylene, C-Calkarylene, oxygen (O), nitrogen (NR), wherein R is H or C-Calkyl; n is 0, 1 or 2 with the proviso that n is 1 when Y is oxygen (O) or nitrogen (NR); each Z is independently C-Calkylene, Carylene, C-Caralkylene or C-Cis alkarylene; m is independently 0, 1 or 2; with the proviso that when Y is oxygen (O) or nitrogen (N), m cannot be 0; each Q is independently C-Calkylene; t is an integer from 1 to 2; W is oxygen (O) or sulphur (S). The compounds are particularly suited as flame retardant additives for thermoplastic polyesters.