| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a methylene-crosslinked polyphenylene polyisocyanate with simply and effectively suppressing discoloration of the same. SOLUTION: The method is to react a polyamine mixture generated by condensation reaction of aniline with formaldehyde in the presence of an acid catalyst with phosgene in the presence of an inactive solvent and produce the methylene-crosslinked polyphenylene polyisocyanate. In the method, (1) after the phosgenation reaction, remaining phosgene is removed from the obtained reaction mixture containing crude methylene-crosslinked polyphenylene polyisocyanate, subsequently (2) an OH-having aromatic compound having a carboxy group at the ortho-position and expressed by formula (I) (wherein R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>and R<SP>4</SP>express each independently H or a 1-6C hydrocarbon group) is added to the crude methylene-crosslinked polyphenylene polyisocyanate and the mixture is treated by heating the same. COPYRIGHT: (C)2006,JPO&NCIPI |
