| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for production of a polyisocyanate of diphenylmethane series. SOLUTION: This method comprises a step (a) reacting aniline and formaldehyde in the presence of HCl to convert to a product mixture containing a polyamine of the diphenylmethane series, HCl, aniline and water, and then (b) removing the excessive aniline and water by distillation to obtain the product mixture containing at most 10mass.% aniline based on total of the polyamine of diphenylmethane series, HCl, polyamine, and at most 5mass.% of water based on the polyamine, and then (c) subjecting the product mixture to a phosgenation. COPYRIGHT: (C)2004,JPO
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