| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for preparing pyromellitic anhydride having particle characteristics causing no problem of occlusion when delivered as a powder. SOLUTION: In the preparation method of the pyromellitic anhydride, pyromellitic acid is dehydrated through indirect heating by a heat transfer medium. After degree of dehydration reaches 99.5%, heating is continued at 200-270°C. COPYRIGHT: (C)2006,JPO&NCIPI
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