Abstract: The present invention is a process for producing a polyester-polycarbonate type thermoplastic polyester elastomer in which a hard segment consisting of a polyester constructed of aromatic dicarboxylic acid, and an aliphatic or alicyclic diol, and a soft segment consisting mainly of aliphatic polycarbonate are connected, comprising at least a step of increasing the molecular weight of an aliphatic polycarbonate diol by a reaction of an aliphatic polycarbonate diol and a chain extender, and a step of reacting aliphatic polycarbonate and a polyester constructed of aromatic dicarboxylic acid and an aliphatic or alicyclic diol in the molten state.

Abstract: The present invention provides a thermoplastic polyester elastomer excellent in heat resistance, heat-aging resistance, water resistance, light resistance, low-temperature property and the like, and further excellent in block order-retaining ability, the thermoplastic polyester elastomer comprising a hard segment which comprises polyester constituted with aromatic dicarboxylic acid and aliphatic or alicyclic diol and a soft segment which comprises mainly aliphatic polycarbonate, wherein the hard segment and the soft segment being connected, and wherein when melting points of the thermoplastic polyester elastomer are obtained by measuring on a differential scanning calorimeter in three cycles in which a temperature is raised from room temperature to 300° C. at a heating rate of 20° C./min., maintained at 300° C. for 3 minutes and lowered to room temperature at a cooling rate of 100° C./min.

Abstract: The present invention is a process for producing a polyester-polycarbonate type thermoplastic polyester elastomer in which a hard segment consisting of a polyester constructed of aromatic dicarboxylic acid, and an aliphatic or alicyclic diol, and a soft segment consisting mainly of aliphatic polycarbonate are connected, comprising at least a step of increasing the molecular weight of an aliphatic polycarbonate diol by a reaction of an aliphatic polycarbonate diol and a chain extender, and a step of reacting aliphatic polycarbonate and a polyester constructed of aromatic dicarboxylic acid and an aliphatic or alicyclic diol in the molten state.

Abstract: The present invention provides a thermoplastic polyester elastomer excellent in heat resistance, heat-aging resistance, water resistance, light resistance, low-temperature property and the like, and further excellent in block order-retaining ability, the thermoplastic polyester elastomer comprising a hard segment which comprises polyester constituted with aromatic dicarboxylic acid and aliphatic or alicyclic diol and a soft segment which comprises mainly aliphatic polycarbonate, wherein the hard segment and the soft segment being connected, and wherein when melting points of the thermoplastic polyester elastomer are obtained by measuring on a differential scanning calorimeter in three cycles in which a temperature is raised from room temperature to 300° C. at a heating rate of 20° C./min., maintained at 300° C. for 3 minutes and lowered to room temperature at a cooling rate of 100° C./min.

Abstract: To easily obtain a polyester having excellent mechanical properties, a satisfactory hue, and a high degree of flame retardancy. [MEANS FOR SOLVING PROBLEMS] The flame-retardant polyester is a polyester comprising ethylene terephthalate units as the main structural units and a phosphorus compound copolymerized or incorporated therein or is a resin composition comprising polyesters including that polyester. The flame-retardant polyester is characterized in that a polycarboxylic acid and/or polyol having three or more functional groups capable of forming an ester bond is contained in the polyester in a total amount of 0.05-2.