THERMOPLASTIC POLYESTER ELASTOMER

PROBLEM TO BE SOLVED: To provide a thermoplastic polyester elastomer that is excellent in heat resistance, heat-ageing resistance, water resistance, light resistance, low-temperature properties and the like, in combination, and exhibits excellent retention of a block property, and easy to regulate melt-viscosity of the thermoplastic polyester elastomer by a chain extender. SOLUTION: The thermoplastic polyester elastomer, comprising a hard segment comprised of a polyester comprising an aromatic dicarboxylic acid and a butane diol and, bonded thereto, a soft segment comprised mainly of an aliphatic polycarbonate, comprises a polyester constituted of an aliphatic diol with at least 5 carbon atoms, wherein the concentration of the carboxyl terminal group of the thermoplastic polyester elastomer is 30-70 eq/ton, and having 0.10-0.50 of the blocking tendency (B) calculated by using formula (1), B=1/x+1/y, in which the average chain length (x) of the hard segment and the average chain length (y) of the soft segment of the thermoplastic polyester elastomer calculated by using nuclear magnetic resonance method (NMR method). COPYRIGHT: (C)2009,JPO&INPIT