| abstract |
1469349 Flame retardant polyesters HOECHST AG 16 Sept 1974 [17 Sept 1973] 40280/74 Heading C3R A flame retardant linear polyester is derived from a dicarboxylic acid, a diol and from 3 to 20 mol. per cent, based on the total acid components, of a carboxyphosphoric acid of the formula in which R is a saturated cyclic or acyclic alkylene radical, an arylene radical or an aralkylene radical and R 1 is a C 1-6 alkyl group, an aryl group or an aralkyl group, or an ester or cyclic anhydride thereof. The polyester preferably contains at least 0À5 weight per cent of phosphorus. The polyester may contain fibres of glass, quartz, asbestos or carbon. The examples describe preparing polyesters from dimethyl terephthalate, optionally with di-methyl isophthalate, ethylene glycol and various phosphinic compounds of the above formula, e.g. 2 - carboxy - ethyl - methylphosphinic acid and 2 - methyl - 2,5 - dioxo - 1 - oxa - 2 - phospholane having the formula |