PRODUCTION OF POLYFUNCTIONAL POLYISOCYANATE COMPOSITION

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a stabilized polyfunctional aromatic polyisocyanate composition. SOLUTION: This method for producing a polyfunctional aromatic polyisocyanate composition selectively containing polynuclear skeletal substances comprises continuously bringing a polymethylenepolyphenylene polyisocyanate mixture into contact with a separating solvent under supercritical conditions in which the temperature and pressure exceed the critical values essential to the substance and mixing the mixture therewith in the presence of an alkyl alkanoate as a diluent.