| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for efficiently and stably producing polyester having a low refractive index and excellent thermal stability, and to provide the polyester in which the formation of cross linking structure is suppressed and the generation of gel is small. <P>SOLUTION: In the method for producing polyester, upon production of polyester satisfying the characteristics of the following (1) to (5) by bringing a dicarboxylic acid component including alicyclic dicarboxylic acid and a diol component including alicyclic diol into ester exchange reaction, and then bringing them into polycondensation reaction, a step of making the alicyclic diol into a slurry state in the presence of an alkali compound (A), thereafter charging it to a reaction can, and holding it at a reaction temperature of 210 to 225°C for 90 to 150 minutes is included, ester exchange reaction is performed at the temperature of 225°C or less, thereafter, a pentavalent phosphorus compound (B) and a titanium compound (C) as a polycondensation reaction catalyst are successively added, and next, polycondensation reaction is caused: (1) glass transition point temperature according to differential scanning calorimetry is 65 to 90°C; (2) its refractive index in a sodium D line is 1.500 to 1.570; (3) the addition amount of the alkali compound (A) is 35 to 150 ppm (to polyester); (4) the phosphorous element content in the pentavalent phosphorus compound (B) is 80 to 120 ppm (to polyester); and (5) the titanium element content in the titanium compound (C) is 1 to 50 ppm (to polyester). <P>COPYRIGHT: (C)2012,JPO&INPIT |
