Abstract: This invention provides a method for synthesizing semi-crystalline polylactides (PLA) even from a lactide mixture including meso-LA and rac-LA. According to the invention, when a mixture of racemic lactide and meso-lactide ispolymerized using a catalyst capable of iso-selectively polymerizing L-lactide and D-lactide, an amorphous poly (meso-lactide) block is formed from meso-lactide and a semi-crystalline poly (racemic lactide) block is formed from racemic lactide by separately polymerizing racemic lactide and meso-lactide by taking advantage of a difference in physicochemical properties between racemic lactide and meso-lactide, whereby polylactide which is semi-crystalline as a whole is produced.

Abstract: To provide a method capable of producing stereocomplex polylactic acid, the method being capable of using carbon neutral materials that are not competitive from foods, such as saccharides, without the use of a method for designing optical resolution, which requires complicated operations and high cost and is difficult to perform mass production. The production method of the present invention comprises: a step of reacting glycerin with sodium hydroxide in high-temperature and high-pressure water to produce a racemic sodium lactate aqueous solution; a step of separating sodium from the racemic sodium lactate aqueous solution to recover racemic lactic acid; a step of dimerizing the racemic lactic acid to produce a lactide mixture containing meso lactide and racemic lactide; a step of separating meso lactide from the mixture to recover racemic lactide; and a step of polymerizing the racemic lactide with a salen-metal complex as a catalyst to produce stereocomplex polylactic acid.

Abstract: This invention provides a method for synthesizing semi-crystalline polylactides (PLA) even from a lactide mixture including meso-LA and rac-LA. According to the invention, when a mixture of racemic lactide and meso-lactide ispolymerized using a catalyst capable of iso-selectively polymerizing L-lactide and D-lactide, an amorphous poly (meso-lactide) block is formed from meso-lactide and a semi-crystalline poly (racemic lactide) block is formed from racemic lactide by separately polymerizing racemic lactide and meso-lactide by taking advantage of a difference in physicochemical properties between racemic lactide and meso-lactide, whereby polylactide which is semi-crystalline as a whole is produced.

Abstract: To provide a method capable of producing stereocomplex polylactic acid, the method being capable of using carbon neutral materials that are not competitive from foods, such as saccharides, without the use of a method for designing optical resolution, which requires complicated operations and high cost and is difficult to perform mass production. The production method of the present invention comprises: a step of reacting glycerin with sodium hydroxide in high-temperature and high-pressure water to produce a racemic sodium lactate aqueous solution; a step of separating sodium from the racemic sodium lactate aqueous solution to recover racemic lactic acid; a step of dimerizing the racemic lactic acid to produce a lactide mixture containing meso lactide and racemic lactide; a step of separating meso lactide from the mixture to recover racemic lactide; and a step of polymerizing the racemic lactide with a salen-metal complex as a catalyst to produce stereocomplex polylactic acid.

Abstract: A process for producing lactic acid according to the invention is characterized in that glycerin is subjected to a hydrothermal reaction under an alkaline condition at a temperature in the range of 150 to 400° C. and under pressure equal to or more than the saturated vapor pressure at the temperature. The glycerin produced from plant fats, animal fats or the like or pure product synthesized chemically or a discharge containing glycerin generated at the production of diesel fuel oil from fats, in which the fats are subjected to a transesterification with alcohol in the presence of an alkali catalyst in order to obtain fatty acid ester is preferably used as a starting material.

Abstract: An apparatus for producing lactic acid according to the invention comprises a reactor carrying out: subjecting glycerin to a hydrothermal reaction under an alkaline condition, supplying an alkaline solution comprising glycerin; and continuously producing lactic acid, wherein glycerin is subjected to a hydrothermal reaction under an alkaline condition at a temperature in the range of 150 to 400° C. and under pressure equal to or more than the saturated vapor pressure at the temperature. The glycerin produced from plant fats, animal fats or the like or pure product synthesized chemically or a discharge containing glycerin generated at the production of diesel fuel oil from fats, in which the fats are subjected to a transesterification with alcohol in the presence of an alkali catalyst in order to obtain fatty acid ester is preferably used as a starting material.

Abstract: A process for producing lactic acid according to the invention is characterized in that glycerin is subjected to a hydrothermal reaction under an alkaline condition at a temperature in the range of 150 to 400° C. and under pressure equal to or more than the saturated vapor pressure at the temperature. The glycerin produced from plant fats, animal fats or the like or pure product synthesized chemically or a discharge containing glycerin generated at the production of diesel fuel oil from fats, in which the fats are subjected to a transesterification with alcohol in the presence of an alkali catalyst in order to obtain fatty acid ester is preferably used as a starting material.