Process for producing pyromellitic dianhydride, pyromellitic dianhydride produced by the method, supply method and supply device of pyromellitic dianhydride

摘要

The present invention with a simple technique and composition, a method for producing high-purity PMDA, provides PMDA prepared by the method, it can be supplied for a long time stable density of PMDA An at least, a (1) pyromellitic dianhydride raw material, dissolved in acetic acid solvent, a step of preparing a raw material solution, a pyromellitic acid in the raw material solution made (2) Re crystallized, the acetic acid solvent is separated, the step of producing the precursor of pyromellitic dianhydride, and (3) the precursor of pyromellitic dianhydride, in a vacuum condition, and stirred in a fluidized state while heating, degassed the step of performing processing, characterized by having a step of (4) degassing the treated pyromellitic dianhydride retrieve processFIELD 1A