Abstract: It is an object of the present invention to provide polylactic acid containing a stereocomplex crystal and having excellent moldability, a high molecular weight, high crystallinity and a high melting point and a process for manufacturing the same. It is another object of the present invention to provide a composition comprising the polylactic acid and a molded product of the polylactic acid. The present invention is characterized from polylactic acid having a weight average molecular weight of 80,000 to 500,000 and a melting peak at 195° C. or higher which accounts for 80% or more of the total of melting peaks in the temperature elevation step when measured by a differential scanning calorimeter (DSC) and a process for manufacturing the same.

Abstract: It is an object of the present invention to provide a composition which contains polylactic acid and has excellent heat stability, mechanical strength and color. The composition contains 0.001 to 0.1 part by weight of a metal catalyst and 0.001 to 0.5 part by weight of a phosphono-fatty acid ester based on 100 parts by weight of polylactic acid.

Abstract: It is an object of the present invention to provide a method for producing a polylactic acid block copolymer having high molecular weight, and in lower cost, wherein only a stereo-complex crystal is capable of growing, even when heat melting process is repeated. The present invention relates to a method for producing a polylactic acid block copolymer characterized in that (i) ring-opening polymerization of D-lactide (D component) is carried out in the presence of poly-L-lactic acid (L component), or (ii) ring-opening polymerization of L-lactide (L component) is carried out in the presence of poly-D-lactic acid (D component), and mass ratio of the D component and the L component is the D component/the L component=60/40 to 91/9, or the L component/the D component=60/40 to 91/9.

Abstract: It is an object of the present invention to provide a method for producing a polylactic acid block copolymer having high molecular weight, and in lower cost, wherein only a stereo-complex crystal is capable of growing, even when heat melting process is repeated. The present invention relates to a method for producing a polylactic acid block copolymer characterized in that (i) ring-opening polymerization of D-lactide (D component) is carried out in the presence of poly-L-lactic acid (L component), or (ii) ring-opening polymerization of L-lactide (L component) is carried out in the presence of poly-D-lactic acid (D component), and mass ratio of the D component and the L component is the D component/the L component=60/40 to 91/9, or the L component/the D component=60/40 to 91/9.

Abstract: It is an object of the present invention to provide a composition which contains polylactic acid and has excellent heat stability, mechanical strength and color. The composition contains 0.001 to 0.1 part by weight of a metal catalyst and 0.001 to 0.5 part by weight of a phosphono-fatty acid ester based on 100 parts by weight of polylactic acid.

Abstract: It is an object of the present invention to provide polylactic acid containing a stereocomplex crystal and having excellent moldability, a high molecular weight, high crystallinity and a high melting point and a process for manufacturing the same. It is another object of the present invention to provide a composition comprising the polylactic acid and a molded product of the polylactic acid. The present invention is characterized from polylactic acid having a weight average molecular weight of 80,000 to 500,000 and a melting peak at 195° C. or higher which accounts for 80% or more of the total of melting peaks in the temperature elevation step when measured by a differential scanning calorimeter (DSC) and a process for manufacturing the same.