Patent ID: 6127493
Filing Date: 2000-10-03
Classification: C08G,Y02P

Abstract:
A process for preparing a polyester from hydroxyalkyl dicarboxylic acid monomers and/or oligomers comprising:a) introducing reaction material having a degree of polymerization of 1 to 40 of hydroxyalkyl dicarboxylic acid ester monomers and/or oligomers into a pipe or tubular reactor, wherein said reaction material has a mole ratio of glycol equivalents to carboxylic acid equivalents of from 1.0:1 to 1.2:1 considering all points of reactant additions to the process;b) introducing a dense gaseous medium into said reactor; andc) operating said reactor at superatmospheric pressure and at sufficient temperature to:1) achieve a turbannular flow regime comprising said reaction material and said gaseous medium before leaving the reactor;2) cause polyesterification to occur whereby the reaction material polymerizes to produce a polyester, with the degree of polymerization 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.