MULTI-STAGE METHOD FOR CONTINUOUSLY PRODUCING ALICYCLIC DIISOCYANATE

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PROBLEM TO BE SOLVED : To provide a multi-stage method for continuously producing an alicyclic diisocyanate without containing phosgene. SOLUTION : This multi-stage method for continuously producing the alicyclic diisocyanate comprises synthesizing an alicyclic diurethane by reacting an alicyclic diamine and an alcohol with urea and/or a urea derivative, removing easily-boiling substances and intermediately-boiling substances from the diurethane, thermally decomposing the diurethane so as to isolate the desired diisocyanate, continuously discharging a part of a bottom reaction product of a decomposing column from a decomposing apparatus, separating a high-boiling component from the discharged product, re-urethanating the discharged product by using the alcohol, and recirculating the re-urethanated product in the above processes.