| 摘要 |
PURPOSE:To obtain a copolyester of an increased toughness, by forming a copolymer consisting of terephthalic acid-based units, aliphatic dicarboxylic acid-based units, ethylene glycol-based units and poly(tetramethylene oxide) glycol-based units. CONSTITUTION:This copolyester substantially consists of structural units of formulas I-IV (these units are hereinafter referred to as I-IV, respectively), wherein R is a bivalent group derived by removing the carboxyl groups from a 9C or higher aliphatic dicarboxylic acid and n is an integer of 8-84 and wherein (I) is bonded to (III) and/or (IV), (II) is bonded to (III) and/or (IV), and the total number of moles of (I) and (II) is substantially equal to that of (III) and (IV), (II) is contained at a rate of 0.2-5mol per 100mol of (I), and (IV) is contained at a proportion of 3-15mol of repeating units of formula V per 100mol of (I). The intrinsic viscosity of this copolyester lies in the range of 0.5-1.5.
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