Patent ID: 6111064
Filing Date: 2000-08-29
Classification: C08G

Abstract:
A process for preparing a polyester from hydroxyalkyl dicarboxylic acid ester monomer and/or oligomers comprising:a) introducing reaction materials having a DP of 1-40 of hydroxyalkyl dicarboxylic acid ester monomers and/or oligomers into a pipe or tubular reactor, wherein said monomer and/or oligomers have a mole ratio of glycol equivalents to carboxylic acid equivalents of from 1.0:1 to 1.2:1 considering all points of addition;b) introducing a dense gaseous medium into said reactor, said dense gaseous medium being an ether, a ketone or a mixture thereof;c) operating said reactor at superatmospheric pressure and at sufficient temperature to:1) achieve a turbannular flow regime comprising said reaction materials and said gaseous medium before leaving the reactor;2) cause polyesterification to occur whereby the reaction material polymerizes to produce a polyester, with the DP of the reaction material polymer increasing from the beginning of the reactor to the end; and3) produce water with little or no other reaction by-products or little or no unreacted monomers or oligomers which are separated from the polymer product through the gaseous medium phase.