Process for the isolation of polyimides in a solid state

摘要

A process is described for the isolation, in a solid state, of polyimides particularly those prepared by interaction of a polyisocyanate and a polycarboxylic anhydride in an organic solvent. A solution of the polyimide is passed into water preferably in the form of droplets or as extruded thin strands. The droplets or strands can be chopped, ground or otherwise comminuted after solidification. The process is particularly applicable to the isolation of solvent-soluble polyimides prepared by reaction of benzophenone tetracarboxylic dianhydride with a mixture of methylenebis(phenyl isocyanate) and toluene diisocyanate.