Kureha Corporation

Michio Kikuchi

Shigeru Suzuki

Kazuyuki Yamane

Masaru Kagoshima

Tomoyuki Ogawa

A method for producing glycolide, including the steps of: heating a mixture containing a glycolic acid oligomer, a high-boiling point polar organic solvent having a boiling point of 230 to 450&#xb0; C., and a tin compound under normal pressure or reduced pressure until a temperature at which the glycolic acid oligomer is depolymerized, to thereby dissolve the glycolic acid oligomer in the high-boiling point polar organic solvent; heating a solution, in which the glycolic acid oligomer is dissolved, under normal pressure or reduced pressure until a temperature at which the glycolic acid oligomer is depolymerized, to thereby form glycolide by depolymerization of the glycolic acid oligomer in the solution; and co-distilling off the high-boiling point polar organic solvent and the formed glycolide from a depolymerization reaction system.

Method for producing glycolide

A process for purification of a hydroxycarboxylic acid by distillation, comprising: distilling a hydroxycarboxylic acid solution containing a high-boiling point hydroxy compound comprising at least one species selected from the group consisting of alcohols and phenols having a higher boiling point than the hydroxycarboxylic acid. As a result, a hydroxycarboxylic acid suitable as a starting material for production of a polyhydroxycarboxylic acid can be obtained. The purified hydroxycarboxylic acid is further polycondensed to provide a hydroxycarboxylic acid oligomer, which is de-polymerized to provide a cyclic ester comprising a dimer of the hydroxycarboxylic acid, and the cyclic ester is converted into a polyhydroxycarboxylic acid by ring-opening polymerization thereof.

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Tokyo, Japan

Michio Kikuchi