| 摘要 |
<p>Disclosed is a process for producing an isocyanate mixture (C). The process comprises a reaction step of introducing an amine mixture (A), phosgene (B), and an inert solvent into a reaction tank (10) and reacting the amine mixture (A) with phosgene (B) to synthesize an isocyanate mixture, and a concentration step of concentrating a liquid, which is produced in the reaction step and comprises the isocyanate mixture, the inert solvent, and acidic compounds such as by-produced hydrogen chloride and excess phosgene, in a concentration tank (20) to remove the inert solvent and the acidic compounds by evaporation from the liquid produced in the reaction step. In the reaction step, the reaction is carried out under reflux of the inert solvent. In the concentration step, at least a part of the inert solvent removed by the evaporation is again returned into the concentration tank (20). At least one of the inert solvent to be refluxed and the inert solvent to be again returned into the concentration tank (20) is treated with an adsorbent (13A) or an adsorbent (23A) before the introduction of the inert solvents into the respective tanks (10, 20). The process can produce an isocyanate mixture having a reduced content of a metal that affects the reactivity of the isocyanate mixture.</p> |
