| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyethylene terephthalate-based polyester composition which goneralies a limited of cyclic trimer of ethylene terephthalate on melting by including antimony atom and a specific compound having a sulfate group. SOLUTION: The objective composition can be obtained by including antimony atom and a compound having one or more kinds of sulfate groups selected from a sulfuric acid salt, a hydrogensulfate salt, a sulfuric acid ester and a hydrogensulfate ester in a polyethylene terephthalate-based polyester, preferably produced from a terephthalic acid component and an ethylene glycol component as essential components, and containing >=80 mol% ethylene terephthalate unit. The composition preferably satisfies the inequality A1/A0<1.7 [A1 is the wt.% of a cyclic triethylene terephthalate(CTET) detected after melting the composition at 280 deg.C for 30 min; A0 is the wt.% of the CTET detected before the thermal melting.
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