A plant and an efficient process for producing polylactic acid

• Main Author: STEPANSKI, MANFRED
• Format: Patent
• Language: Chinese; English
• Published: 01.03.2024
• Subjects: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAININGELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN,SULFUR, SELENIUM OR TELLURIUM; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; COMPOSITIONS BASED THEREON; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METALLURGY; ORGANIC CHEMISTRY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; THEIR PREPARATION OR CHEMICAL WORKING-UP; THEIR RELEVANT APPARATUS; TRANSPORTING

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 less than 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 optionally 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 or a mixture of the meso-lactide enriched composition and a portion of the composition containing unreacted lactide to a purification comprising at least one crystallization step so as to produce a purified meso-lac