CONTINUOUS PRODUCTION OF ISOCYANATE

PURPOSE:To produce the titled compound having high quality, continuously, without producing a resinous by-product, in high space hour yield, by decomposing a mixture of a specific heat-decomposition solvent and a carbamic acid ester in two steps with a reactor comprising a combination of a tubular reactor and a tank reactor. CONSTITUTION:A mixture of 1-50wt% carbamic acid ester and 99-50wt% inert heat-decomposition solvent having a boiling point falling between the boiling point of the produced isocyanate and that of the hydroxyl compound, is flowed down in the first reactor consisting of a tubular reactor and is decomposed at a temperature (T deg.C) and pressure sufficient to evaporate the decomposition product having low boiling point. The reaction mixture obtained from the bottom of the reaction tube is introduced into the second reactor consisting of a tank reactor maintained at a temperature between (T1-50) deg.C and (T1+50) deg.C to effect the second decomposition. The decomposition product having low boiling point is taken out continuously from the first reactor or the first reactor and the second reactor, and the decomposition product having high boiling point is taken out continuously from the second reactor.