Patent ID: 8258253
Filing Date: 2012-09-04
Classification: C08G

Abstract:
1. A method for the preparation of a polyester, which method comprises in a first step, reacting a dicarboxylic acid or a C in a second step, reacting the precondensate to effect polycondensation at a suitable temperature and pressure to prepare a high molecular weight polyester and in a third step, further increasing the molecular weight and viscosity of the polyester under solid state polymerization conditions of a suitable temperature and pressure, where a metal catalyst is added at one or more points where a phosphinic acid compound is added at one or more points where the phosphinic acid compounds are of formula I where R hydrogen; C straight or branched chain C straight or branched chain C straight or branched chain C straight or branched chain C where each of the aryl or arylene groups are unsubstituted or are substituted by one to three straight or branched chain C —(CH or R R C straight or branched chain C straight or branched chain C straight or branched chain C straight or branched chain C straight or branched chain C straight or branched chain C 3,5-di-tert-butyl-4-hydroxyphenyl; —(CH 3-oxo-1,3-dihydroisobenzofuran-1-yl which is unsubstituted or is substituted by one to three straight or branched chain C R hydrogen; C C straight or branched chain C straight or branched chain C straight or branched chain C straight or branched chain C where each of the aryl or arylene groups are unsubstituted or are substituted by one to three straight or branched chain C —(CH 3-oxo-1,3-dihydroisobenzofuran-1-yl which is unsubstituted or is substituted by one to three straight or branched chain C or R R and R′ are independently hydrogen or straight or branched chain C m is from 2 to 100 and where the metal catalyst is present from about 1 ppm to about 500 ppm by weight metal, based on the weight of dicarboxylic acid or dicarboxylic diester and diol.