Method of producing polyester and charging apparatus therefor

摘要

This invention provides a method of producing polyester and charging apparatus therefor capable of producing a high quality polyethylene naphthalate usable for photographic purpose from recovered polyethylene naphthalate which comprises subjecting an ester-forming derivative consisting essentially of naphthalene dicarboxylic acid or its lower alkyl ester and a diol compound consisting essentially of ethylene glycol to ester exchange reaction or esterification to produce polyethylene naphthalate, wherein recovered polyethylene naphthalate resin is charged before beginning of effusion of alcohol or water which is a by-product of the ester exchange reaction or esterification, and a charging apparatus comprising a slidable inner pipe capable of penetrating through a supply valve.