화학공학소재연구정보센터
Polyesters
Get Adobe Flash player
원료 TPA (DMT); EG
생산물 polyesters
적용 Processes for the production of polyethylene terephthalate (PET) starting from ethylene glycol (EG) and terephthalic acid (TPA) or dimethylterephthalate (DMT).
설명 Description: In a multistage continuous process the raw materials EG and TPA (DMT) are comverted into a low-molecular precondensate by esterification (transesterification) and into high molecular, linear polymer by polycondensation reaction. Two routes are available for the esterification reaction:

   1. Process being carried out under atmospheric pressure with corresponding ease of recycling and charging solid waste.
   2. A more common process being carried out under pressure and addition of TPA and EG as paste.

   The reaction byproducts water (methanol) is separated from EG vapors in a reflux column. After adding catalyst, stabilizer and additives the prepolymer is forced through a superfine filter. Polycondensation reaction is performed under vacuum and elevated temperature. Special care went into the conception of the polymer finisher, which is equipped with a proprietary horizontal cage agitator without center-shaft, therefore minimizing the buildup of solidifying polymer layers. EG vapors contaminated with oligomers are drawn off through a special condensing system and sent to a recovery unit.
   Polymer melt can either be sent to a direct spinning plant or transformed to chips. These continuous processes are available with capacities ranging from 30 to 120 t/d per line.
   The cooperation between EMS-INVENTA AG and Karl Fischer Industrieanlagen GmbH makes available an industrially well proven package of continuous polyester process and production known-how.

Batch process: Similar principles are applied to a two-stage batch process. The capacity of standard batch lines ranges up to 30 t/d.
   Existing batch transesterification plants can be converted to TPA feedstock by adding one continuous esterification reactor. TPA as feedstock is often more economical than DMT.
   PET is used for the production of textile and technical grade fiber and filament yarn, bottles, film and plastic materials.