A polymeric composition and a PET/PEN copolyester suitable for manufacturing pasteurizable containers

摘要

A polymeric composition suitable for manufacturing pasteurizable containers comprising, polyethylene terephthalate (PET) in the ratio of 80 to 95 mass % by mass of the total composition; polyethylene naphthalate (PEN) in the ratio of 20 to 5 mass % by mass of the total composition; tungsten trioxide in the range of 10 to 100 ppm by mass of the composition and particle size of 2 to 20 microns; and optionally a nucleating agent and a polycondensation catalyst.
A method for making PET/PEN copolyester for manufacture of pasteurizable containers comprising the following steps:
a. mixing pure terephthalic acid and monoethylene glycol in an esterification reactor and optionally adding a nucleating agent, a polycondensation catalyst and colorants;
b. mixing naphthalene dicarboxylic acid or naphthalene di carboxylate in an esterification reactor for in-situ PEN formation;
c. conducting the esterification reaction at a temperature of 240 to 265°C for 190 minutes to obtain an esterified pre-polymer;
d. transferring the esterified pre-polymer to a polycondensation reactor;
e. subjecting the pre-polymer to polycondensation at a temperature of 265-292°C under pressure of 5-15 mbar for 180 minutes to obtain a molten amorphous polymer;
f. extruding the molten amorphous polymer under nitrogen pressure to form chips; and
g. subjecting the resulting chips to solid state polymerization to attain an I.V. greater than 0.70 dL/gm.