Thermotropic aromatic copolyesters and processes for their preparation

Abstract

A thermotropic carbonate polyester of high molecular weight which can be shaped is disclosed, characterized in that it possesses an inherent viscosity of more than 0.3 dlg.sup.-1 (measured on a solution containing 0.5 g of polymer in 100 cm.sup.3 of a 50/5 by volume mixture of para-chlorophenol and 1,2-dichloroethane) and a flow point which is above or equal to 150.degree. C. and below 330.degree. C., and in that it consists essentially of units of the formulae: --O--R--O--.sub.a, --O--R.sub.1 --O--.sub.b (I) ##STR1## and ti --CO--R.sub.2 --CO-- (III) in which the radicals R, which are identical, each represent a para-phenylene radical which is monosubstituted by a methyl or ethyl group or a chlorine or bromine atom; the radicals R.sub.1 each represent an unsubstituted paraphenylene radical, with 0.3.ltoreq.a.ltoreq.1, 0.ltoreq.b.ltoreq.0.7 and a+b=1; and the radicals R.sub.2, which may be identical or different, each represent a radical chosen from amongst para-phenylene, 1,4-cyclohexylene, 4,4'-biphenylene, 2,6-naphthylene, 1,1'(4,4'-ethylenedioxydiphenylene), 1,1'-(4,4'-butylenedioxydiphenylene) and 1,1'-(4,4'-hexylenedioxydiphenylene) groups, the amount of the units (II) in the mixture (II)+(III) being between 30 and 90 mol % and the molar ratio of the units (I) to the sum of units (II)+(III) being between 0.95 and 1.05. A process for making the thermotropic carbonate polyester is also disclosed.

Dependencies are inferred from the claim text.