| 摘要 |
A modifier for a polylactic acid comprising a block polymer (C) having a polymer block (A) satisfying relationship (1): <?in-line-formulae description="In-line Formulae" end="lead"?>7.80<=sigma/rho<8.54<?in-line-formulae description="In-line Formulae" end="tail"?> wherein sigma represents a solubility parameter value of a polymer block; and rho represents a density value of a polymer block, and a polymer block (B) satisfying relationship (2): <?in-line-formulae description="In-line Formulae" end="lead"?>8.54<=sigma/rho<9.20<?in-line-formulae description="In-line Formulae" end="tail"?> wherein sigma and rho 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.
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