Process for producing poly(1,4-cyclohexylenedimethylene 1,4-cyclohexanedicarboxylate) and the reactor grade polyester therefrom

摘要

In a process for producing a reactor grade polyester, a poly(1,4-cyclohexylenedimethylene 1,4-cyclohexanedicarboxylate) has a reduced amount of isomerization of the trans-isomer to the cis-isomer of 1,4-dimethylcyclohexanedicarboxylate and an increased polymerization rate by the addition of a phosphorus-containing compound to the reaction process. In step (a) of the process, a diacid comprising at least 80 mole percent 1,4-cyclohexanedicarboxylic acid or an ester derivative of the diacid comprising at least 80 mole percent 1,4-dimethylcyclohexanedicarboxylate is reacted with a glycol comprising at least 80 mole percent 1,4-cyclohexanedimethanol at a temperature sufficient to effect esterification for the diacid or transesterification for the ester derivative. In step (b), the product of step (a) is subjected to temperatures and pressures in the presence of a suitable catalyst to effect polycondensation. Phosphorus in an amount of 1 to 800 ppm is added in the form of a phosphorus-containing compound during the process.