Patent ID: 8895774

Claim:
A process for producing an isocyanate, comprising the steps of: obtaining a reaction mixture containing an aryl carbamate having an aryl group originating from a diaryl carbonate, an aromatic hydroxy compound originating from a diaryl carbonate, and a diaryl carbonate, by reacting a diaryl carbonate comprising metal atoms at from 0.001 ppm to 10% and an amine compound in a reaction vessel in which a reaction between the diaryl carbonate and the amine compound is carried out; transferring the reaction mixture to a thermal decomposition reaction vessel connected by a line with the reaction vessel in which the reaction between the diaryl carbonate and the amine compound is carried out; and obtaining the isocyanate by applying the aryl carbamate to a thermal decomposition reaction, wherein a low boiling point component formed in the thermal decomposition reaction is recovered from the thermal decomposition reaction vessel in the form of a gaseous phase component, and a liquid phase component is recovered from a bottom of the reaction vessel, and the recovery of the gaseous phase component and the recovery of the liquid phase component are carried out continuously; wherein the amine compound is a polyamine compound; and an acid cleaning solvent is present in the thermal decomposition reaction.