PROCESS FOR PRODUCING POLYETHYLENE TEREPHTHALATE

摘要

A process for producing a polyethylene terephthalate in which the amount of the oligomers, such as cyclic trimer etc., is lower and which causes metal mold staining to occur difficultly. The process comprises an esterification stage in which dicarboxylic acids including mainly terephthalic acid or ester- forming derivatives of such acids are esterified with glycols including mainly ethylene glycol or with ester-forming derivatives of such glycols; a liquid phase polycondensation stage in which the esterified product obtained in the esterification stage is subjected to a polycondensation in a liquid phase containing a polycondensation catalyst and having a content of an alkaline solubilizing agent of 0.4 mole or less per mole of the polycondensation catalyst with heating; a solid phase polycondensation stage in which the polycondensation product obtained in the liquid phase polycondensation stage is heated at a temperature below the melting point of the product in an inert atmosphere; and an aqua-treatment stage in which the polycondensation catalyst is deactivated by contacting the polycondensation product obtained in the solid phase polycondensation stage with water. The polyethylene terephthalate obtained by this process is suitable as the material for containers to be charged with drinks.