METHOD FOR PRODUCING METHYLENE-CROSSLINKED POLYPHENYLENE POLYISOCYANATE

摘要

PROBLEM TO BE SOLVED: To provide a method for the production of a methylene-crosslinked polyphenylene polyisocyanate to efficiently and effectively decrease the hydrolyzable chlorine content and acid content. SOLUTION: The method for the production of a methylene-crosslinked polyphenylene polyisocyanate comprises the condensation of aniline with formaldehyde in the presence of an acid catalyst and the phosgenization of the produced methylene-crosslinked polyphenylene polyamine. In the production of a crude product by reacting the methylene-crosslinked polyphenylene polyamine with phosgene in an organic solvent, hydrogen chloride gas is blown into the solution of the obtained crude product and an inert gas is blown into the system under heating to decrease the hydrolyzable chlorine content and the acid content in the crude product. The contents of hydrolyzable chlorine and acid in the methylene-crosslinked polyphenylene polyisocyanate can be decreased in high efficiency with a smaller amount of hydrogen chloride gas than conventional processes. COPYRIGHT: (C)2004,JPO