Rapid poly-condensn. of oligo:carbonate(s) to high mol. wt. polycarbonate(s) - by passing the oligo:carbonate together with inert gas through a heated tube of specified dimensions, etc

摘要

In the prodn. of aromatic polycarbonates from aromatic oligocarbonates of average Mw 2000-20000 by opt. catalysed melt esterification at 200-400 deg.C at least one polycondensation stage is effected with the oligocarbonate passing through a heated tube where (i) an inert gas is simultaneously introduced into the tube in an amt. of at least 1m3/kg oligocarbonate melt; (ii) the length/dia. ratio of the tube is 10-200:1; and (iii) the ratio of polycarbonate throughput (in kg/hr.) to tube vol. (in litres) is 2-20:1. ADVANTAGE - Oligocarbonates obtd. by conventional methods can be rapidly polycondensed to high mol.wt. prods.