Nagoya University

Hitachi Zosen Corporation

Tohoku Electric Power Company, Inc.

Natureworks LLC

Nobuyoshi Nomura

Takashi Hasegawa

Hisanori Kishida

Joseph David Schroeder

Takehiko Moriya

Makoto Takahashi

Manuel Aw Natal

Kenji Miyaguchi

Ryohei Ogawa

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.

Method to produce semi-crystalline polylactides

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.

Method for producing polylactic acid

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Nagoya, Japan

Nobuyoshi Nomura