METHOD FOR REMOVING LOW MOLECULAR WEIGHT SUBSTANCE FROM POLYIMIDE PRECURSOR OR POLYIMIDE CONTAINING THE SUBSTANCE

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently removing a low molecular weight substance from a polyimide precursor or a polyimide wherein the substance is microdispersed without using a large amount of an organic solvent. SOLUTION: The method for extracting and removing the substance from a polymer composition having a micro phase separation structure wherein a non-continuous phase comprising the substance is dispersed in a continuous phase comprising the precursor or a polyimide composition obtained by converting the precursor of the polymer composition of the polyimide using a cosolvent for extracting together with carbon dioxide in a supercritical state is provided. As the cosolvent, an aprotic polar solvent is preferably used and more preferably a nitrogen compound based solvent or a sulfur compound based solvent is used.