The present invention relates to a polyester block copolymer composition which
is obtained by reacting 0.5 to 5.0 parts by weight of an epoxy compound (C) having
two or more functionalities with 100 parts by weight of a polyester block copolymer
(P) having an acid value of 0 to 5 mgKOH/g obtained by reacting a crystalline aromatic
polyester (A) having a hydroxyl group at a molecular terminal with a lactone (B)
and optionally with a polyfunctional compound (D) having three or more groups selected
among carboxyl, hydroxyl, and/or ester groups thereof. The composition has such
excellent moldability that it is applicable to molding techniques including blow
molding without arousing any trouble. It is satisfactory in heat resistance, water
resistance, impact resistance, or flame retardancy, and has rubber-like elasticity.
