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

摘要

This invention 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 to 80 psig 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.