Abstract

This invention relates to a method and device for producing high molecular weight polymers, including polylactide, polyglycolide, and polycaprolactone, with low polydispersity through a four-stage process: pre-polymerization, intermediate polymerization, final polymerization, and devolatilization. The process employs supercritical carbon dioxide, introduced either before or after the intermediate polymerization stage, in combination with a specially designed static mixing reactor and a phase separation vessel during final polymerization. Supercritical carbon dioxide improves heat and mass transfer while leveraging its solvating properties to effectively extract volatiles, such as monomers, oligomers, and catalysts, from the polymer matrix. In the phase separation vessel, the supercritical carbon dioxide-rich phase rises, extracting dissolved volatiles from the top of the vessel. During devolatilization, the dissolved supercritical carbon dioxide within the polymer serves as a stripping agent, ensuring the effective removal of residual impurities and resulting in high-quality, purified polymers.

IPC Classes  ?

• C08G 63/78 - Preparation processes
• C08G 63/08 - Lactones or lactides

Abstract

This invention relates to a method for the continuous production of optically pure lactide comprising a first reactive distillation system, a second reactive distillation system, a main distillation system and the side-draw refluxer. For each of the four systems a novel horizontally top-mounted condenser is used in order to decrease its total pressure drop and thus reduce side-reactions associated with high bottom temperature. In addition, a wiped film evaporator, a short path evaporator or a combination thereof is utilized for the concentration of the purge stream from the second reactive distillation, in a purpose of removing the metal contaminants contained in the purge stream and depolymerizing the contained unconverted lactic acid oligomers to crude lactide, all of which give additional advantages for the lactide production.

IPC Classes  ?

• C07D 319/12 - 1,4-DioxanesHydrogenated 1,4-dioxanes not condensed with other rings
• B01D 3/00 - Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
• B01D 3/14 - Fractional distillation
• B01D 5/00 - Condensation of vapoursRecovering volatile solvents by condensation

Abstract

This invention relates to a process for the continuous production of optically pure lactide from an aqueous solution of lactic acid by means of two reactive distillations followed by a main distillation column with a side-draw refluxer. The first reactive distillation is used for the preparation of lactic acid oligomers and the second reactive distillation used for the depolymerization of the thus obtained lactic acid oligomers to lactide. The crude lactide generated from the second reactive distillation is further purified in the main distillation column with a side-draw refluxer being connected to.

IPC Classes  ?

• C07D 319/12 - 1,4-DioxanesHydrogenated 1,4-dioxanes not condensed with other rings

Abstract

This invention relates to a method for the continuous production of optically pure lactide comprising the first reactive distillation, the second reactive distillation, the main distillation and the side-draw refluxer. For each of the four systems a novel horizontally top-mounted condenser is used in order to decrease its total pressure drop and thus reduce side-reactions associated with high bottom temperature. In addition, a wiped film evaporator, a short path evaporator or a combination thereof is utilized for the concentration of the purge stream from the second reactive distillation, in a purpose of removing the metal contaminants contained in the purge stream and depolymerizing the contained unconverted lactic acid oligomers to crude lactide, all of which give additional advantages for the lactide production.

IPC Classes  ?

• C07D 319/12 - 1,4-DioxanesHydrogenated 1,4-dioxanes not condensed with other rings
• B01D 5/00 - Condensation of vapoursRecovering volatile solvents by condensation

Abstract

This invention relates to a method for the continuous production of optically pure lactide comprising the first reactive distillation, the second reactive distillation, the main distillation and the side-draw refluxer. For each of the four systems a novel horizontally top-mounted condenser is used in order to decrease its total pressure drop and thus reduce side-reactions associated with high bottom temperature. In addition, a wiped film evaporator, a short path evaporator or a combination thereof is utilized for the concentration of the purge stream from the second reactive distillation, in a purpose of removing the metal contaminants contained in the purge stream and depolymerizing the contained unconverted lactic acid oligomers to crude lactide, all of which give additional advantages for the lactide production.

IPC Classes  ?

• C07C 59/08 - Lactic acid
• C07D 319/12 - 1,4-DioxanesHydrogenated 1,4-dioxanes not condensed with other rings

Abstract

This invention relates to a process for the continuous production of optically pure lactide from an aqueous solution of lactic acid by means of two reactive distillations followed by a main distillation column with a side-draw refluxer. The first reactive distillation is used for the preparation of lactic acid oligomers and the second reactive distillation used for the depolymerization of the thus obtained lactic acid oligomers to lactide. The crude lactide generated from the second reactive distillation is further purified in the main distillation column with a side-draw refluxer being connected to.

IPC Classes  ?

• C08G 63/08 - Lactones or lactides
• C07D 319/12 - 1,4-DioxanesHydrogenated 1,4-dioxanes not condensed with other rings
• C07B 57/00 - Separation of optically-active organic compounds
• B01D 3/34 - Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
• C08G 63/78 - Preparation processes

Abstract

The present invention relates to a method for the separation of meta-phenylenediamine from the ortho-phenylenediamine and para-phenylenediamine by means of distillation, wherein the distillation may be performed in one stage, i.e. a main distillation stage or in two stages, i.e. a secondary distillation stage prior to a main distillation stage. In any case, a divided wall column is used in the main distillation stage.

IPC Classes  ?

• C07C 211/51 - Phenylenediamines
• C07C 209/86 - Separation