Polylactide manufacturing apparatus and method

摘要

In a process of manufacturing polylactide, synthesis of high-quality polymers is achieved with a sufficient degree of vacuum secured. Provided is an apparatus for manufacturing polylactide which includes the steps of preparing lactide through oligomerization of lactic acid and depolymerization of the resulting oligomers, effecting ring-opening polymerization of the lactide, and removing unreacted lactide. The apparatus comprises an exhausting gas treatment device for reducing pressure in the step of removing unreacted lactide. The exhausting gas treatment device includes boilers (81-83) for generating water vapor; a pressure-reducing section having stages each including an ejector (71-73) driven with the water vapor, a condenser (61-63) connected downstream of the ejector, and a hot well tank (41-43) connected to the condenser; and a main condenser (60) and a main hot well tank (40) connected to the main condenser that are disposed on a pipe line through which a gas of the unreacted lactide is suctioned into the pressure-reducing section. The gas of the unreacted lactide is washed away in the main condenser using a liquid containing lactic acid as a main component that has been collected in the main hot well tank.