PURPOSE: To provide a process for producing an aliphatic polyisocyanate capable of reducing usage of phosgene, preventing tar formation, increasing yield and performing other improvements by introducing an inert gas into the reaction system during the reaction of an aliphatic polyamine, or its hydrochloric acid salt or carbonic acid salt with phosgene in an inert liquid medium.
CONSTITUTION: An aliphatic polyisocyanate is obtained by reacting an aliphatic polyamine, or its hydrochloric acid salt or carbonic acid salt with phosgene in an inert liquid medium. During the reaction, an inert gas (especially preferably nitrogen) is introduced into the reaction system. Preferable examples as the aliphatic polyamine include xylilenediamine, hexamethylenediamine, trimethylhexamethylenediamine, isophoronediamine, bis(aminocyclohexyl)methane, 2,2-bis(aminomethyl)propane, bis(aminomethyl) cyclohexane and bis(aminomethyl) norbornene. The reaction is preferably carried out in an inert liquid medium (especially an ester) having a boiling point of ≥130°C. This is a method for producing aliphatic polyisocyanate using phosgene at a low cost in high yield.
KANEMURA YOSHINOBU
NAGATA TERUYUKI
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