Kureha Corporation

Yoshiko Ikeyama

Kazuyuki Yamane

Kensuke Suzuki

Nanako Saigusa

A method for producing a GL comprising: (I) a heating step of heating a mixture either under normal pressure or reduced pressure at a temperature at which a polyglycolic acid (PGA) undergoes depolymerization, the mixture containing the PGA and a polyethylene glycol ether which is represented by the formula: X&#x2014;O&#x2014;(&#x2014;CHCH&#x2014;O&#x2014;)&#x2014;Y (wherein X and Y are each independently an alkyl group or an aryl group having from 2 to 20 carbon atoms, and p is an integer from 1 to 5) and which has a molecular weight of from 150 to 450 and a boiling point of from 130 to 220&#xb0; C. at a pressure of 3 kPa; (II) a solution-forming step in which the mixture is rendered in a solution state in which a melt phase of the PGA and a liquid phase consisting of the polyethylene glycol ether essentially form a uniform phase; (III) a GL production step in which a glycolide (GL) is produced by a depolymerization reaction of the PGA by continuing to heat the mixture in the solution state; (IV) a distillation step of distilling off the produced GL together with the polyethylene glycol ether (B) from the depolymerization reaction system; and (V) a recovery step of recovering the GL from the distillate.

Method for producing glycolide

A method for producing glycolide (GL) by heating a glycolic acid oligomer (GAO) to depolymerize the GAO. The method for producing GL comprises: a step 1 of heating a mixture containing a GAO having a terminal COOH concentration of 400 eq/t or less and a polar organic solvent to a GAO depolymerization temperature under ambient pressure or reduced pressure; a step 2 of continuing the heating at the temperature for depolymerizing of the GAO and then codistilling out the produced GL and the solvent from the depolymerization reaction system to the outside the reaction system; and a step 3 of obtaining GL from the codistillation product. In the method for producing GL, the GAO is preferably prepared by a GAO production method which comprises a step of condensing glycolic acid (GA) and a dehydration step of continuing the heating together with a polar organic solvent or a depolymerization reaction solution to allow the GA condensation reaction to continue. 

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Tokyo, Japan

Yoshiko Ikeyama