Patent ID: 11939280

Abstract:
A method for preparing isophorone diisocyanate by (1) reacting isophorone with hydrogen cyanide in the presence of a catalyst to obtain isophorone nitrile; (2) reacting the isophorone nitrile obtained in step (1) with ammonia gas and hydrogen in the presence of a catalyst to obtain isophorone diamine; and (3) subjecting the isophorone diamine to a phosgenation reaction to obtain the isophorone diisocyanate, wherein the content of impurities containing a secondary amine group in the isophorone diamine that undergoes the phosgenation reaction in step (3) is ≤0.5 wt. The method reduces the content of hydrolyzed chlorine in the isophorone diisocyanate product, improves the yellowing resistance of the product, and the harm due to presence of hydrolyzed chlorine in the product is reduced.