PROCESS AND APPARATUS FOR THE PRODUCTION OF OLIGOMERIC ALKYLENE BENZENE DICARBOXYLATES

摘要

A process and an apparatus for the production of an oligomeric alkylene benzene dicarboxylate, in particular an alkylene terephthalate in which the alkylene group contains at least three carbon atoms, is disclosed. There is employed a column reactor for effecting transesterification of a starting dialkyl benzene dicarboxylate, in particular dimethyl terephalate, with a selected diol, the transesterification being carried out at ambient of slightly higher pressure and the reaction mixture employed containing catalyst for the transesterification and passing downwardly through the column from the uppermost chamber in which the reactants are first provided. The transesterification product is then subjected to a condensation to produce an oligomer by heating under reduced pressure in a separate chamber or chambers. The condensation chamber(s) may be located at the foot of the column reactor for the transesterification. The oligomer produced is particularly suitable for subsequent condensation to produce polymers having high reduced viscosities.