To provide a method for efficiently and also effectively reducing a hydrolytic chlorine content and an acid content in the method for producing a methylene-cross-linked polyphenylenepolyisocyanate.
This method for the methylene-cross-linked polyphenylenepolyisocyanate comprises the steps of, in reducing the hydrolytic chlorine content and acid content in a crude product by blowing an inert gas into the obtained crude product under heating condition, performing a first treating process of supplying the crude product continuously into a continuous treating vessel under the heating condition, also blowing the inert gas into the vessel and continuously discharging the treated crude product, then supplying at least a part of the crude product obtained by the first treating process into a batch vessel and performing a second treating process by further blowing nitrogen gas into the batch vessel to reduce the hydrolytic chlorine content and acid content in the crude product.
IZUKAWA TSUKURU
Koji Makimura
Chihata Takahata
Toru Suzuki