THERMOSTABLE FLAMEPROOFING AGENT FOR COPOLYESTERS, PROCESS FOR MAKING IT, COPOLYESTER COMPOSITIONS PREPARED BY USING IT, PROCESS FOR MAKING SAID COMPOSITIONS AND FORMED BODIES MADE FROM SAID COMPOSITIONS

摘要

The invention is concerned with a thermostable flameproofing agent for copolyester compositions, which comprises the reaction product of 1 mole of a dialkyl diester of an alkali dicarboxyaryl-sulphonate having the general formula: wherein R' represents an alkyl radical containing from 1 to 3 carbon atoms and M represents an alkali metal atom, with 1 to 2 moles of at least one tetrabrominated diol having the general formula: wherein a and b represent, independently one of the other, a whole number from 1 to 3 inclusive; the reaction is effected in the presence of a transesterification catalyst selected from the group consisting of compounds of Zn, Co, Ca, Sn, Ti and Mn. The flame-proofing agent of the invention imparts to polyester materials, besides improved self-extinguishing properties, a considerable thermostability with a substantial improvement of the resistance to the propagation of flame.