Continuous process for production of a polyethylene terephthalate condensate

Claim 1

A CONTINUOUS FOUR-STASTE PROCESS FOR PRODUCTION OF A POLYETHYLENE TEREPHTHALATE CONDENSATE FROM DIMETHYL TEREPHTHALATE AND ETHYLENE GLYCOL BY TRANSESTERIFICATION AND POLYCONDENSATION WHICH COMPRISES: LIQUEFING DIMETHYL TEREPHALATE AND MIXING EXCESS ETHYLENE GLYCOL THEREWITH IN A MOLAR RATIO OF SAID ETHYLENE GLYCOL TO SAID DIMETHYL TERETPHTHALATE OF LESS THAN ABOUT 1.5:1 TO FORM A LIQUID REACTION MIXTURE IN A FIRST STAGE AT A TEMPERATURE BELOW THAT AT WHICH TRANSESTERIFICATION OCCURS, CONDUCTING SAID LIQUID REACTION MIXTURE IN CONTINUOUS LIQUID FLOW FROM SAID FIRST STAGE THROUGH THREE SUCCEDDING STAGES WHICH ARE SPATIALLY SEPARATED FOR SEPARATE TEMPERATURE CONTROL AND WHICH ARE IN LIQUID COMMUNICATION TO FORM A CONTINUOUS LIQUID PHASE REACION SYSTEM, SUCH THAT THE LIQUID REACTION MIXTURE IS (A) TRANSESTERIFIED IN THE SECOND STAGE AT A TEMPERATURE OF NOT MORE THAN 197*C. IN THE PRESENCE OF A TRANSESTERIFICATION CATALYST, (B) HEATED IN THE THIRD STAGE TO A TEMPERATURE OF FROM 197*C. TO NOT MORE THAN 230*C. WHILE REMOVING VAPOROUS REACTION PRODUCTS DIRECTLY FROM THE THIRD STAGE BY PASSING AN INERT GAS THROUGH THE LIQUID REACTION MIXTURE IN SAID THIRD STAGE SEPARATELY FROM THE OTHER STAGES, AND (C) POLYCONDENSED IN THE FOURTH STAGE AT A TEMPERATURE OF FROM 230*C. TO 270*C. FOR A PERIOD OF TIME SUFFICIENT TO PRODUCE A FILAMENT-FORMING POLYETHYLENE TEREPHTHALATE CONDENSATE WHILE REMOVING VAPOROUS REACTION PRODUCTS FROM THE FOURTH STAGE BY PASSING AN INERT GAS THROUGH THE LIQUID REACTION MIXTURE; AND RECOVERING SAID POLYETHYLENE TEREPHTHALATE CONDENSATE PRODUCT FROM SAID FOURTH STAGE AT A RATE APPROXIMATELY EQUAL TO THE RATE AT WHICH REACTANT MATERIALS ARE ADDED TO THE FIRST STAGE.