Technical parameters of batch solid state post condensation

The S5Tithesis of PET in a DMT-BPU (batch polycondensation unit) process is a two step reaction  

After reaching the end temperature of the ester interchange process which depends on the type of PET (technical PET, textile PET), the catalyst for the polycondensation process is added. 

The polycondensation process is finished when the desired intrinsic viscosity, which depends on the type of product, is reached. The PET is pressed out by N2, cooled with water (normal/deionised), cut, dried and sieved. The cut PET chips are then stored in storage silos for further processing. 

Polyester raw materials are stored in silos. The material is weighed and pneumatically conveyed to the in-feed hoppers of polyester dryers. Prior to drying, the pol mier is crystallised at temperatures of between 150 and 200 °C in an agitated bed, to prevent agglomeration. 

The dried polyester polymer is transported to extruders where it is melted, and piunped to spinning packs held in a spin manifold. The spin packs contain spiimeiets with a large number of fine holes through which the melted polymer flows to form filaments. Any contaminants in the polymer are removed by filtration prior to the spinneret. Different spinneret designs enable a wide range of fibre cross-sections to be produced including solid round, hollow and trilobal. 

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Table 10.3 Technical parameters of batch solid state post condensation...

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