| 摘要 |
PROBLEM TO BE SOLVED: To recover a purified cyclic ester from a co-distillate from a depolymerization system containing a depolymerization solvent and a cyclic ester produced by thermal depolymerization of a hydroxycarboxylic acid oligomer in the presence of the depolymerization solvent with high heat efficiency, purification efficiency and handleability. SOLUTION: A method for purifying the cyclic ester is characterized as follows: The co-distillate of the cyclic ester produced by thermal depolymerization reaction of the hydroxycarboxylic acid oligomer in the presence of the depolymerization solvent and the depolymerization solvent is mixed with an organic solvent for washing having compatibility with the depolymerization solvent and a lower boiling point than that of the cyclic ester. The resultant mixture liquid is subjected to liquid-liquid separation into an organic solvent phase containing the depolymerization solvent and a cyclic ester phase containing the organic solvent. Furthermore, the organic solvent is then evaporated from the cyclic ester phase containing the organic solvent to thereby recover the cyclic ester with the reduced depolymerization solvent. COPYRIGHT: (C)2008,JPO&INPIT
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