Process for preparing copolyesters of terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol exhibiting neutral hue, high clarity and increased brightness

摘要

This application relates to a three step process for preparing copolyesters exhibiting a neutral hue, high clarity and increased brightness. The process involves reacting terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol in a feed mole ratio of total glycols to dicarboxylic acid of 1.7:1 to 6.0:1 at a temperature of 240 DEG C to 280 DEG C, and a pressure of 15 psig (200 kPa) to 80 psig (650 kPa) to form an esterification product; adding a polycondensation catalyst and a toner; and polycondensing the product at a temperature of 260 DEG C to 290 DEG c and a reduced pressure to form a high molecular weight copolyester.