To provide a method for decomposing isocyanate-based compounds and a method for recovering the decomposed materials in order to solve problems in which a mixture of isocyanate-based compounds has no utility value and the mixture has been discarded by burning, etc., though when chemical process of refining of an isocyanate compound by distillation is carried out, the distillation residue of the isocyanate compound is produced and becomes the mixture of isocyanate-based compounds such as isocyanate, urea and isocyanate tar-like oligomer.
The mixture of isocyanate-based compounds are decomposed in high-temperature state by using an alcohol compound or a phenol compound. The decomposition temperature is 180-250°C when the alcohol compound is used and the decomposition temperature is 120-210°C when the phenol compound is used. A carbamate produced by decomposition is recovered as a pure product or a part of the mixture. An isocyanate can be obtained by further pyrolysis of the carbamate.
SAKAI KEISUKE
MORIYOSHI TAKASHI
