Method for preparing isocyanate compound

A method for preparing an isocyanate compound, comprising:

• a reaction step of reacting a salt of amine compound with phosgene in the presence of a solvent to obtain a reaction product containing an isocyanate compound,
• a degassing step of removing a gas phase from the reaction product,
• a scrubbing step of contacting the gas phase obtained in the degassing step with a cleaning solvent having a temperature of −15 °C to 0 °C under an absolute pressure of 700 torr or more and less than 760 torr to obtain a phosgene-containing solution,
• a distillation step of distilling the phosgene-containing solution under normal pressure to separate the phosgene contained in the phosgene-containing solution and the cleaning solvent,
• a desolvation step of removing a solvent from the reaction product from which the gas phase obtained in the degassing step has been removed,
• a low boiling material-removing step of removing low boiling materials having a boiling point lower than that of the isocyanate compound from the reaction product from which the solvent has been removed, and
• a high boiling material-removing step of removing high boiling materials having a boiling point higher than that of the isocyanate compound from the reaction product from which the low boiling materials have been removed,
• wherein the phosgene obtained in the distillation step is supplied to the reaction step, and
• wherein the cleaning solvent obtained in the distillation step is supplied to the scrubbing step,
• wherein the desolvation step, the low boiling material-removing step, and the high boiling material-removing step are each progressed at a temperature of 165 °C or less,
• wherein the desolvation step is progressed at a temperature of 100 °C to 165 °C and a pressure of 30 torr or less.