Cargill Inc.

Natureworks LLC

Richard Douglas Benson

Jeffrey John Kolstad

Patrick R Gruber

Eric Stanley Hall

Ronald L Borchardt

Matthew L Iwen

Scott D Bloomer

Joseph David Schroeder

Paraskevas Tsobanakis

Eric Stanley Sumner

Paris Tsobanakis

Matthew L Iwan

Manuel AW Natal

Lactic acid equivalents are recovered from a starting lactide stream by catalytically racemizing a portion of the lactide in the stream at a temperature of 180&#xb0; C. or below. This increases the proportion of two species of lactide (i.e., at least two of S,S-, R,R- or meso-lactide) at the expense of the third species. The racemized mixture so obtained can be separated to recover some or all of one or more of the lactide species from the remaining lactide species, by a process such as melt crystallization or distillation. Impurities in the starting lactide stream usually are retained mostly in the remaining meso-lactide, so a highly purified S,S- and/or R,R-lactide stream can be produced in this manner. Such a purified S,S- and R,R-lactide stream is suitable for polymerization to form a polylactide.

Recovery of lactic acid values from a meso-lactide stream

Thermoformed PLA stereocomplex parts are made using a PLA stereocomplex composition having a highest crystallization melting temperature from 200 to 215&#xb0; C. The stereocomplex composition preferably has less than 5 J/g of lower melting (160 to 190&#xb0; C.) crystallites. The stereocomplex can be pre-annealed in various ways to reduce thermoforming cycle times. The stereocomplex forms parts with low haze and good thermal resistance, at reasonable cycle times.

Polylactic acid stereocomplex compositions and methods for making and using same

An S,S- and R,R-lactide stream suitable for polymerization is prepared by producing a low molecular weight poly(lactic acid), depolymerizing the low molecular weight poly(lactic acid) to form a mixture of S,S-, R,R- and meso-lactide, and separating meso-lactide from this mixture to form an S,S- and R,R-lactide stream. Meso-lactide is recycled into the process, and shifts the mole fractions of the lactides in the lactide mixture that is produced.

Methods for producing lactide with recycle of meso-lactide

A process for the continuous production of substantially purified lactide and lactide polymers from lactic acid or an ester of lactic acid including the steps of forming crude polylactic acid, preferably in the presence of a catalyst means in the case of the ester of lactic acid, to form a condensation reaction by-product and polylactic acid, and depolymerizing the polylactic acid in a lactide reactor to form crude lactide, followed by subsequent purification of the crude lactide in a distillation system. A purified lactide is then polymerized to form lactide polymers.

Continuous process for the manufacture of lactide and lactide polymers

A process for the continuous production of polylactide polymers from lactic acid which incorporates removal of water or a solvent carrier to concentrate the lactic acid feed followed by polymerization to a low-molecular-weight prepolymer. This prepolymer is fed to a reactor in which a catalyst is added to facilitate generation of lactide, the depolymerization product of polylactic acid. The lactide generated is continuously fed to a distillation system as a liquid or vapor wherein water and other impurities are removed. The resultant purified liquid lactide is fed directly to a polymerization process.

Continuous process for manufacture of lactide polymers with controlled optical purity

A method of preparing purified ester compositions is provided. The process can be utilized to isolate and purify monoglycerides and propylene glycol monoesters, to advantage. It can also be used to isolate preferred diester products. The invention also concerns equipment for conduct of the processes, provision of preferred food additives, and provision of preferred food industry compositions. The process generally involves use of liquid-liquid extractions, to advantage.

Method for preparation of purified glycerides, and, products

Continuous process for manufacture of lactide polymers with controlled

Method for preparation of purified glycerides and products

A method of preparing a purified monoester composition is provided. The method generally involves a step of adding triglycerides to the crude monoester composition, with a follow up step of extracting into an alcohol/water phase, of the monoester to be purified. The process can be utilized to isolate and purify monoglycerides and propylene glycol monoesters, to advantage. The invention also concerns equipment for conduct of the processes, provision of preferred food additives, and provision of preferred food industry compositions.

Method for preparation of purified monoglycerides; and, products

Continuous process for manufacture of lactide polymers with purification

A process for the continuous conversion of crude lactic acid to a substantially purified lactide or polylactide including the steps of polymerizing the lactic acid to form a prepolymer with subsequent depolymerization to form a crude lactide in the presence of a catalyst. The crude lactide is purified in an improved distillation system in which at least three fractions are formed with the substantially purified lactide removed as an intermediate boiling sidedraw stream. The substantially purified lactide may then be polymerized.

Continuous process for manufacture of a purified lactide

A process for the continuous production of substantially purified lactide and lactide polymers from an ester of lactic acid including the steps of forming crude lactide in the presence of a catalyst means to form a condensation reaction by-product and polylactic acid and depolymerizing the polylactic acid molecules followed by subsequent purification of the crude lactide in a distillation system. A purified lactide is then polymerized.

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Long Lake, MN, United States of America

Richard Douglas Benson