Polyester polymerization process

Abstract

The present invention relates to a process for producing PET based on titanium catalyst having acceptable properties for resin used in the production of bottles for beverages. More particularly the invention relates to a process in which the incoming pre-polymer temperature is higher than the final outlet temperature in the final melt phase polycondensation reactor.

Description

FIELD OF INVENTION[0001]The present invention relates to a process for producing PET based on titanium catalyst having acceptable properties for resin used in the production of bottles for beverages. More particularly the invention relates to a process which allows for significantly lower capital cost and / or lower operating cost by introducing a higher incoming pre-polymer temperature as compared to the final melt temperature in the final melt phase polycondensation reactor.BACKGROUND OF INVENTION[0002]Polyethylene terephthalate and its copolyesters (“PET”) are used extensively in packaging applications, in particular as beverage containers. The conventional PET production process begins with esterification of predominantly terephthalic acid and ethylene glycol, or ester exchange of predominantly dimethyl terephthalate and ethylene glycol at a temperature of about 265° C. The esterification need not be catalyzed. Typical ester exchange catalysts, which may be used separately or in c...

AI Technical Summary

Benefits of technology

The invention is about a method for making solid polyester polymer resin. This involves creating an oligomer mixture of diacids and diols, and then polycondensing it in the presence of a catalyst at a high temperature. The resulting polymer is then solidified and cut into particles. These particles can also undergo additional polymerization to increase their IV (a measure of molecular weight and size) by more than 0.1 dl / g. Overall, this process produces a high-quality solid polyester polymer resin with improved properties.

Problems solved by technology

Whether this resin, quenched and cut into pellets, is used directly from the melt polymerization process, or after a solid state polymerization process, when processed into extrusion blown, or injection stretch blown bottles, the level of AA is unacceptably high and influences the taste of the liquid in the bottle.

This therefore reduces the capacity of the continuous polymerization lines.

One remaining problem associated with this approach is that the process described is necessarily costly with long residence times in esterification to maintain the proscribed temperatures.