| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To efficiently produce a polylactic acid-based resin having a high molecular weight and a high melting point in a preferable embodiment and excellent in heat stability and color hue. <P>SOLUTION: The method for producing the polylactic acid-based resin is to directly polycondense lactic acid as a main raw material without a solvent and comprises the following 3 processes: (A) a first process for producing a low molecular weight material having <10,000 weight-average molecular weight under at least 3 conditions selected from the following conditions: (a-1) no catalyst, (a-2) a temperature of 100-180°C, (a-3) a pressure of 0.13-1,300 Pa and (a-4) a reaction time of 0.3-15 hours; (B) a second process for producing a prepolymer having >10,000 to <100,000 weight-average molecular weight in the presence of a catalyst; and (C) a third process for producing a polymer having≥100,000 weight-average molecular weight by carrying out a solid phase polymerization under a temperature equal to or lower than the melting point of the prepolymer. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
