POLYLACTIC ACID RESIN COMPOSITION

PROBLEM TO BE SOLVED: To obtain a polylactic acid resin composition which is excellent in strength and impact resistance and can be decomposed by a microorganism at a regulated rate, by incorporating a modified olefin compound into a polylactic acid in a specific weight ratio. SOLUTION: The composition comprises a polylactic acid (A) and a modified olefin compound (B) in an (A)/(B) weight ratio of 99.5/0.5 to 40/60. The use of an unmodified olefin is undesirable in that it has such a poor compatibility with the polylactic acid (A) as to reduce the strength of the composition. The compound (B) has one of the following structures (1) and (2): (1) an epoxidized olefin copolymer made from (a) an α-olefin, (b) a monomer having an ethylenic bond and a glycidyl group, and (c) a (meth)acrylic ester or styrene; and (2) a copolymer obtained by grafting an unsaturated carboxylic acid or a derivative thereof onto a copolymer of ethylene with another α-olefin.