Method for producing lactide and apparatus used therefor

摘要

The method for producing lactide includes the steps of (a) synthesizing lactide using lactic acid as a starting material; (b) discharging in gaseous states lactide synthesized and impurities formed upon synthesis in step (a); (c) liquefying gaseous components in step (b) and solidifying only lactide, to thereby separate the impurities from the thus-obtained solidified lactide; and (d) returning the separated impurities in step (c) back to the synthesis step (a). The apparatus used for the above production includes (a) a reactor for carrying out synthesis of lactide; (b) a means for gasifying synthesized lactide and impurities formed upon synthesis in the reactor (a) and discharging the resulting gaseous components; (c) a means for cooling the gaseous components to liquefy the gaseous components obtained by the means (b) and solidify only lactide; and (d) a pipe for returning to the reactor (a) components which are not solidified by the means (c).