PURPOSE: To obtain the titled polyester capable of providing films excellent in easy slidability, etc., by adding specified amounts of a Zn compound and a Ca compound before completion of the esterification reaction and adding a specified amount of a P compound before completion of the precondensation reaction in producing the polyester.
CONSTITUTION: In producing a polyester mainly consisting of repeating ethylene terephthalate units by a direct polymerization process, a Zn compound (e.g., zinc acetate) and a Ca compound (e.g., calcium oxide) in amounts satisfying formula I and II [wherein Zn and Ca are amounts (ppm, in terms of Zn and Ca atoms, respectively) of the Zn and Ca compounds] in an arbitrary stage before completion of the esterification reaction. A P compound (e.g., methylphosphonic acid or dimethyl phenylphosphonate) in an amount satisfying formula III is added in an arbitrary stage before completion of the precondensation reaction to obtain the purpose internal particle-containing polyester.
MATSUYAMA YUUJIROU
HASHIMOTO HIROSHI
NAKAMURA KOUICHIROU
MAKIMURA OSAMU
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