Biphenyltetracarboxylic Acid Dianhydride and Process for Producing the Same, and Polymide Formed from the Same and Process for Producing Same

摘要

To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1x10² Pa to 1.1x10⁵ Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼0 of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.