The process description is as follows
Polyester chips are manufactured by two step chemical reactions between PTA ( Pure terephtalic acid ) and MEG (Mono ethylene glycol) The two step reaction are : Esterfication and Poly condensation
Process description : PTA and MEG mixed together in paste mixing tank. Mixing of paste is done by special type of agitator. The slurry obtained in paste tank is fed to esterification reactor by screw pump. The esterification reaction is carried out under pressure and at high temperature of 265 deg C . Mole ratio of 1:1.19 is maintain in the reactor. Theoretical mole ratio requirement is 1: 1.01 Monomer is the product of esterification reaction. Water is evolved in the esterification process as byproduct The water is distilled off by distillation column and send to ETP for further treatment Esterification reaction dose not required catalyst. We add some additives like NaAc = Max PPM , OPA = Max PPM , Penta- Erythritol = Max PPM. These additives increases the performance of Polymer Polycondensation reaction is carried out under vacuum and high temperature in the range of 292 to 300 deg C. This reaction is carried out with the help of catalyst. EG is evolved in the reaction. Which we collect as crude EG and distilled off further recycling. The catalyst used in the process is Sb2O3 = Max ppm The additives used in polycondensation reaction are SiO2 and SiO2 concentration in polymer is Max PPM and that of is Max PPM Generally reaction time in polycondensation reactor is 2hours 15 minutes after that melt is ready for casting , casting is done on cutter to make pellet of polymer. These chips are further conveyed to respective silo for bagging. The complete process is controlled by DCS operation.