A plant and an efficient process for producing polylactic acid using lactide obtained from polylactic acid devolatilization

• Main Author: STEPANSKI, MANFRED
• Format: Patent
• Language: Chinese; English
• Published: 16.03.2024
• Subjects: CHEMISTRY; COMPOSITIONS BASED THEREON; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

A process of producing polylactic acid comprising the steps of: (a) providing a crude lactide composition comprising meso-lactide and at least one of L-lactide and D-lactide, (b) separating from the crude lactide composition a meso-lactide enriched composition and a meso-lactide depleted composition, wherein the meso-lactide enriched composition contains at least 80 mol-% of meso-lactide based on the total content of lactide, (c) polymerizing a polymerization composition comprising meso-lactide and at least one of L-lactide and D-lactide to a crude polylactic acid composition and devolatilizing the crude polylactic acid composition so as to produce a purified polylactic acid composition and a composition containing unreacted lactide, (d) subjecting the meso-lactide enriched composition and at least a portion of the composition containing unreacted lactide to a purification comprising at least one crystallization step so as to produce a purified meso-lactide enriched composition, (e) subjecting the meso-lactid