Abstract: A modifier for a polylactic acid comprising a block polymer (C) having a polymer block (A) satisfying relationship (1): 7.80??/?<8.54 wherein ? represents a solubility parameter value of a polymer block; and ? represents a density value of a polymer block, and a polymer block (B) satisfying relationship (2): 8.54??/?<9.20 wherein ? and ? have the same meanings as described above, wherein each of the aforementioned polymer block (A) and the aforementioned polymer block (B) is independently a polymer block selected from the group consisting of a polyester block, a polyether block, and a polyhydroxycarboxylic acid block, and said block polymer (C) has a glass transition temperature of 0° C. or lower, can enhance impact resistance, flexibility, and tensile strain, while biodegradability of the polylactic acids and thermal resistance are maintained, and in addition, is free from bleed-out from the moldings formed from a polylactic acid composition.

Abstract: A molding resin formed from a block copolymer comprising polyhydroxycarboxylic acid structural units (I), and polyester structural units (II) derived from a dicarboxylic acid and a diol; wherein the weight ratio (I)/(II) between the polyhydroxycarboxylic acid structural units (I) and the polyester structural units (II) is within a range from 95/5 to 10/90; the resin has a microphase separated structure in which either the polyhydroxycarboxylic acid structural units (I) or the polyester structural units (II) forms domains within a matrix formed by the other structural units; the average domain size of the domains is within a range from 0.08 to 5.0 ?m; and the weight average molecular weight of the molding resin is within a range from 10,000 to 400,000.

Abstract: A molding resin formed from a block copolymer comprising polyhydroxycarboxylic acid structural units (I), and polyester structural units (II) derived from a dicarboxylic acid and a diol; wherein the weight ratio (I)/(II) between the polyhydroxycarboxylic acid structural units (I) and the polyester structural units (II) is within a range from 95/5 to 10/90; the resin has a microphase separated structure in which either the polyhydroxycarboxylic acid structural units (I) or the polyester structural units (II) forms domains within a matrix formed by the other structural units; the average domain size of the domains is within a range from 0.08 to 5.0 ?m; and the weight average molecular weight of the molding resin is within a range from 10,000 to 400,000.

Abstract: A modifier for a polylactic acid comprising a block polymer (C) having a polymer block (A) satisfying relationship (i) 7.80??/?<8.54 wherein ? represents a solubility parameter value of a polymer block; and ? represents a density value of a polymer block, and a polymer block (B) satisfying relationship (2): 8.54??/?<9.20 wherein ? and ? have the same meanings as described above, wherein each of the aforementioned polymer block (A) and the aforementioned polymer block (B) is independently a polymer block selected from the group consisting of a polyester block, a polyether block, and a polyhydroxycarboxylic acid block, and said block polymer (C) has a glass transition temperature of 0° C. or lower, can enhance impact resistance, flexibility, and tensile strain, while biodegradability of the polylactic acids and thermal resistance are maintained, and in addition, is free from bleed-out from the moldings formed from a polylactic acid composition.

Abstract: A lactic acid polyester (III), having a lactic acid unit (I) and a polyester unit (II) at a weight ratio within the range of 10:90 to 90:10, a weight average molecular weight of 10,000 or more, and a glass transition temperature of 60° C. or below, imparts superior impact resistance to polyhydroxy carboxylic acids while maintaining superior flexibility and transparency and with minimal occurrence of bleedout.