High melt viscosity thermoplastic polyesters prepn. - by including ethylenic diol, e.g. butene-2-diol-1,4, or dicarboxylic acid in reactants

摘要

Thermoplastic polyesters with melt viscosity >6000 P at 250 degrees C and a relative viscosity >1.6 determined in a 2/1 mixt. of phenol and o-dichlorobenzene at 25 degrees C, are prepd. by melt polycondensn. of (cyclo)aliphatic diols with dicarboxylic acids and/or esters in the presence of 0.1-10 mole % of an aliphatic diol (I) with ethylenic bond(s) and/or an aliphatic dicarboxylic acid (II) with ethylene bond(s) which is not directly adjacent to the COOH or ester gps., the polycondensation taking place at least partly at >220 degrees C, pref. >230 degrees C. The polyesters have high viscosity, clear colour and good stability during processing. They are partic. suitable for prepg. injection mouldings with thick walls and high mechanical strength and also for extrusion and blow-moulding.