Patent ID: 7138481
Filing Date: 2006-11-21
Classification: C08G

Abstract:
1. A process for producing a polyester resin, which comprises: polycondensing a dicarboxylic acid component containing terephthalic acid or an ester-forming derivative thereof as the main component and a diol component containing ethylene glycol as the main component, wherein the reacting components contain comonomers other than terephthalic acid and ethylene glycol in total amount of 5.5 mol % or less, by esterification or transesterification; melt polymerizing the polycondensed material obtained, thereby obtaining a polymerized product having an intrinsic viscosity ranging from 0.08 dL/g to 0.50 dL/g and an apparent crystallite size smaller than 9 nm; and solid-phase polycondensing the melt polymerized product obtained at a temperature which is higher by at least 140° C. than the glass transition temperature of the melt polymerization polymer and is not higher than the melting point of the polymer to thereby obtain a polyester resin having an apparent crystallite size smaller than 9 nm and having an intrinsic viscosity of 0.60 dL/g or higher.