| 摘要 |
PROBLEM TO BE SOLVED: To provide a preparation process of a copolymerized polyester, which does not deteriorate the color tone and the heat resistance when copolymerizing a dicarboxylic acid component for imparting a gas-barrier property. SOLUTION: In a preparation process of a copolymerized polyester resin, a dicarboxylic acid component, wherein the essential component is terephthalic acid or it ester-forming derivative and the copolymerizable component is phenylenedioxydiacetic acid, is polycondensed with a diol component essentially comprising ethylene glycol, via esterification or transesterification. Here, phenylene dioxydiacetic acid used as a raw material has a monohydroxyphenyleneoxydiacetic acid content of <=0.2 wt.%, a phenylenedioxytriacetic acid content of <=1.0 wt.% and a transmittance of a light ray having a wave length of 400 nm in a 10 wt.% aqueous alkaline solution of >=90%.
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