| abstract |
PROBLEM TO BE SOLVED: To provide a method for producing a polyester which is excellent in transparency, heat resistance, mechanical properties and aroma retention and can be advantageously used as a container or packaging material for food or beverages. In a method for producing a polyester in which a melt polycondensation polyester having ethylene terephthalate as a repeating unit is solid-phase polymerized in an inert gas atmosphere, the intrinsic viscosity of the melt polycondensation polyester is 0.45 to 0.75 dl / g. The acetaldehyde content is 100 ppm or less, the free ethylene glycol content is 70 ppm or less, and the oxygen concentration in the inert gas atmosphere is 300 ppm or less, and the dew point of the washed inert gas used for circulation in the solid phase polymerization apparatus is − It is a manufacturing method of polyester characterized by being 10 degrees C or less. [Selection figure] None |