Patent attributes
In a method for producing a cyclic ester according to an embodiment of the present invention, a mixture (I) containing an aliphatic polyester, a specific polyalkylene glycol diether, and a sulfonic acid compound as a thermal stabilizer is prepared and heated in predetermined conditions to obtain a mixture (II) in a state of solution. Furthermore, heating of the mixture (II) is continued to distill, together with the polyalkylene glycol diether, a cyclic ester formed by the depolymerization reaction, and thus a distillate (III) is obtained. The cyclic ester is recovered from the distillate (III). At this time, a specific solubilizing agent is added to at least one of the mixture (I) or (II). In this production method, the sulfonic acid compound as the thermal stabilizer is contained in the mixtures (I) and (II) and the distillate (III).
