METHOD FOR PRODUCING DICARBOXYLIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a dicarboxylic acid as a raw material for practicable polyesters of high molecular weight with slight discoloration. SOLUTION: The content of ammonia as one of impurities in a dicarboxylic acid obtained by a fermentation method is a significant cause of the decline in the rate of polymerization for a relevant polyester and the discoloration of related resins. Based on the above fact, a dicarboxylic acid obtained by a production method comprising a fermentation process is subjected to a refining process comprising rinsing with water and/or a crystallization step to bring the ammonia content of the dicarboxylic acid to 4,000 ppm or less. COPYRIGHT: (C)2009,JPO&INPIT