METHOD FOR CHEAPLY PREPARING TYPE D LACTIDE FROM TYPE D LACTIC ACID

摘要

PURPOSE: A method for preparing type D lactide from type D lactic acid of a liquid phase is provided to lower cost for preparing type D polylactic acid.;CONSTITUTION: A method for preparing type D lactide comprises: a step of converting type D lactic acid into type D polylactic acid at 130-150 Deg. C. and a pressure of 10-200 torr; a step of heating the type D polylactic acid under a zinc oxide catalyst at 230-240 Deg. C. to convert the liquid phase into a gas phase stream; a step of cooling the gas phase stream at -78 Deg. C. to 10 Deg. C. and separating the gas phase stream into unreacted lactic acid and a mixture; a step of mixing the mixture and water and isolating type D lactide.;COPYRIGHT KIPO 2013;[Reference numerals] (a) Reactor; (b) Mixture; (c) Lactic acid recycle; (d) Water; (e) Pure lactide