| 摘要 |
PROBLEM TO BE SOLVED: To provide a thermoplastic polyester elastomer having excellent heat resistance, thermal ageing resistance, water-resisting property, light resistance, low temperature characteristics or the like as a coating material for an optical fiber, and having excellent block holding property. SOLUTION: The following thermoplastic polyester elastomer is used as the coating material for the optical fiber. The polyester elastomer comprises coupled segments: a hard segment comprising a polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol; and a soft segment essentially comprising an aliphatic polycarbonate. The polyester elastomer exhibits such properties that: when the thermoplastic polyester elastomer is subjected to three times of thermal cycles by raising a temperature from room temperature to 300°C at a temperature rising rate of 20°C/min, keeping at 300°C for 3 minutes and then lowering the temperature to room temperature at a temperature lowering rate of 100°C/min by using a differential scanning calorimeter, the difference in the melting point (Tm1-Tm3) between a melting point (Tm1) measured at a first measurement and the melting point (Tm3) measured at a third measurement is 0 to 50°C; and the elastomer has a tensile strength of 15 to 100 MPa at fracture. COPYRIGHT: (C)2008,JPO&INPIT
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