PROCESS FOR PRODUCING TOLUENE DIISOCYANATE

PROBLEM TO BE SOLVED: To provide a simple process for producing TDI in which the cost and the energy consumption necessary for the post-treatment of residues are minimum, and further, the loss in the yield of TDI and the formation of residual substances to be discarded are both minimum. SOLUTION: The process for producing TDI comprises reacting toluenediamine with phosgene, to form crude toluene diisocyanate, purifying the crude toluene diisocyanate by distillation to form purified toluene diisocyanate and a mixture containing toluene diisocyanate and a distillation residue of toluene diisocyanate, continuously mixing the mixture with water at a temperature of lower than 230°C under absolute pressure of less than 30 bar, reacting the above mixture under the same conditions in one or more tubular reactors connected in series, to form toluenediamine and, optionally, purifying the resultant toluenediamine component and recirculating at least a part of the purified toluenediamine to the reaction step. COPYRIGHT: (C)2008,JPO&INPIT