METHOD FOR PRODUCING ISOCYANATE MIXTURE

PROBLEM TO BE SOLVED: To provide a method for producing an isocyanate mixture reduced in the content of a metal affecting the reactivity of the isocyanate mixture. SOLUTION: There is provided the method for producing the isocyanate mixture C, having a reaction process for introducing an amine mixture A, phosgene B and an inactive solvent into a reaction vessel 10 and reacting the amine mixture A with the phosgene B to synthesize the isocyanate mixture, and a concentration process for concentrating the reaction process liquid comprising the isocyanate mixture, an inactive solvent and an acidic compound such as the by-produced hydrogen chloride or the excessive phosgene in a concentration vessel 20 to distill away the inactive solvent and the acidic compound from the reaction process liquid, wherein the reaction is performed in a condition for refluxing the inactive solvent in the reaction process, and at least one part of the inactive solvent distilled away is again returned to the concentration vessel 20 in the concentration process, characterized in that at least one of the refluxed inactive solvent and the inactive solvent again returned to the concentration vessel 20 is treated with an adsorbents 13A or 23A, before introduced into the vessel 10 or 20. COPYRIGHT: (C)2010,JPO&INPIT