To industrially and continuously acquire the subject compound useful as a raw material for plastic foam, etc., in bulk in a state that the composition of nuclei (rings) can be controlled by the pressure and temperature of a supercritical fluid by subjecting a specific mixture of isocyanates to extraction treatment using a supercritical fluid and an adsorbent.
This multifunctional aromatic polyisocyanate compound is acquired by extraction-treating (A) a mixture of isocyanates of the formula [(n)≥0] (in which the content of binuclear isocyanate is ≥50 wt.%) with (B) a supercritical fluid and (C) an adsorbent such as diatomaceous, etc. The component B is pref. supercritical carbonic acid gas, and on this occasion, the extraction is pref. conducted at 7.38-40 MPa and at 31.05-50°C. The purpose of this invention is suitably realized by the following process: feeding the component A from a raw material storage tank 1 and the component B from a carbonic acid gas bomb 3 into an extractor 5 filled with the component C through a supercritical fluid converter 4 to make the components A, B and C contact with one another and then by feeding the extract containing the component B, and the residue into reclaimers 6, 7 for respective the extract and the residue.
CHIBA MITSURU
ARAI SUMUTO
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