| abstract |
[PROBLEMS] To provide terephthalic acid suitable as a raw material for a direct polymerization method of polyester with a simple equipment and method. SOLUTION: A high-temperature and high-pressure reaction solution obtained by hydrolyzing dimethyl terephthalate is cooled by flash, and a water slurry of terephthalic acid particles thus obtained is subjected to solid-liquid separation to obtain a wet terephthalic acid cake. Upon obtaining, when the conversion of the hydrolysis becomes 97% or more, the temperature of the reaction solution is set to 190 to 240 ° C., and then the conversion is made 99% or more. [Selection diagram] None |