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.

A method for removing compounds in the gaseous aggregate state from PLA-containing products in the viscous aggregate state by means of a thin-film evaporator. The compounds may be present in the liquid or solid aggregate state in the products under standard conditions. The invention further relates to a polylactide resin prepared in accordance with the method of the invention.

Biomass (e.g., plant biomass, animal biomass, and municipal waste biomass) is processed to produce useful intermediates and products, such as aliphatic hydroxy-carboxylic acid and hydroxyl-carboxylic acid derivatives. These aliphatic hydroxy-carboxylic acids are, in turn, polymerized. The polymerization is carried out using a thin film evaporator or a thin film polymerization/devolatilization device. Conversion of lactic acid to poly lactic acid is an especially useful product to this process.

Disclosed is a process to produce a purified vapor comprising dialkyl-furan-2,5-dicarboxylate (DAFD). Furan-2,5-dicarboxylic acid (FDCA) and an alcohol in an esterification zone to generate a crude diester stream containing dialkyl furan dicarboxylate (DAFD), unreacted alcohol, 5-(alkoxycarbonyl)furan-2-carboxylic acid (ACFC), and alkyl furan-2-carboxylate (AFC). The esterification zone comprises at least one reactor that has been previously used in an DMT process.

In a practicable continuous or batchwise process for the preparation of a crystallizable polylactic acid mixture, lactic acid may be polycondensed to yield an oligomer, which may then be depolymerized to yield a crude lactide. The crude lactide may be purified to yield a pure lactide, wherein fractionation may be carried out in the purification into an L- or D-lactide-rich fraction and also a meso-lactide-rich fraction. Subsequently a separate ring-opening polymerization of the resulting lactide fractions can be carried out. The individual polylactic acid batches or streams generated by the ring-opening polymerization may then be mixed. The present disclosure further relates to apparatuses for carrying out such processes and polylactic acid mixtures.

Disclosed is a continuous process and device for making polybutylene terephthalate (PBT) resin, particularly high molecular weight PBT resin. Also disclosed are a device for conducting the process, and a monitoring process for determining the carboxylic acid end group concentration of the resulting PBT.

A process of continuously manufacturing a poly(hydroxy acid) copolymer is provided. The process comprises copolymerizing at least two different monomers in the presence of a catalyst in a reactor system by ring-opening-polymerization. At least one of the monomers is a cyclic ester of hydroxy acid. A molar ratio of a total amount of the different monomers to a total amount of the at least one catalyst is more than 10,000. The reactor system comprises in series at least two polymerization reactors including a continuous stirred-tank reactor, a loop reactor or a plug flow reactor, one of the reactors comprising at least one of a mixer and a heat transfer element. The reactor system comprises at least two different feeding points through each of which a monomer composition is fed. A first monomer composition fed through one feeding point is different from a second monomer composition fed through another feeding point.

Provided are a biodegradable aliphatic-aromatic polyester copolymer having excellent hydrolysis resistance and high viscosity which has a carboxyl end group (CEG) content of 15 mg KOH/g or less, a ratio (Mz/Mn) of a z-average molecular weight (Mz) to a number average molecular weight (Mn) of 3 to 15, and a melt index (MI) of 5 g/10 min or less as measured under conditions of a temperature of 190? C. and a load of 2.16 kg in accordance with ASTM D 1238. A method of preparing a biodegradable aliphatic-aromatic polyester copolymer is provided, including adding a chain extender and an anti-hydrolysis agent to an aliphatic-aromatic polyester pre-copolymer over time, whereby a significant viscosity rise and improvement of hydrolysis resistance may be implemented simultaneously.

Provided are a biodegradable aliphatic-aromatic polyester copolymer having excellent hydrolysis resistance and high viscosity which has a carboxyl end group (CEG) content of 15 mg KOH/g or less, a ratio (Mz/Mn) of a z-average molecular weight (Mz) to a number average molecular weight (Mn) of 3 to 15, and a melt index (MI) of 5 g/10 min or less as measured under conditions of a temperature of 190? C. and a load of 2.16 kg in accordance with ASTM D 1238. A method of preparing a biodegradable aliphatic-aromatic polyester copolymer is provided, including adding a chain extender and an anti-hydrolysis agent to an aliphatic-aromatic polyester pre-copolymer over time, whereby a significant viscosity rise and improvement of hydrolysis resistance may be implemented simultaneously.

Disclosed is a continuous process and device for making polybutylene terephthalate (PBT) resin, particularly high molecular weight PBT resin. The process includes combining 1,4-butane diol and purified terephthalic acid to form a mixture and continuously supplying the mixture to a tower reactor having a plurality of reactor zones for esterification and/or transesterification. The product is continuously supplied to a first continuously stirred tank reactor, and further to a continuous polycondensation reactor. Particular conditions for each step of the process are further described herein. Also disclosed are a device for conducting the process, and a monitoring process for determining the carboxylic acid end group concentration of the resulting PBT.