| 摘要 |
PROBLEM TO BE SOLVED: To provide solid polylactic acid affording sufficiently high mechanical strength even at high temperatures of about glass transition point temperature Tg and to provide a method for producing the solid polylactic acid. SOLUTION: The solid polylactic acid comprises poly-D-lactic acid having 300,000-1,500,000 weight-average molecular weight (Mw) and poly-L-lactic acid having 300,000-1,500,000 Mw. The method for producing the solid polylactic acid is carried out as follows: a poor solvent having a low solubility of the poly-D-lactic acid and the poly-L-lactic acid as compared with a good solvent is added to a solution prepared by dissolving the poly-D-lactic acid and the poly-L-lactic acid in the good solvent and maintained at the deposition temperature to thereby deposit a stereocomplex crystal. In the method, the good solvent is chloroform and the poor solvent is toluene. The method can be composed as follows: the amount added of the poor solvent added to the good solvent is an amount so as to afford 0.65-0.85 fraction and the deposition temperature is within the range of 20-75°C. COPYRIGHT: (C)2008,JPO&INPIT
|
