PROCESS FOR PREPARING ISOCYANATES

摘要

Isocyanates are prepared by a continuous process, by reacting appropriate primary amines with phosgene in the presence of an isocyanate as solvent. The primary amine optionally dissolved in an inert organic solvent is reacted with phosgene, which is dissolved in the isocyanate, at temperatures of between 60 and 150 ~C and pressures of between 1 and 30 bar (105 to 3.106Pa) to form the corresponding isocyanate. The molar ratio of phosgene to the amine used is between 4:1 and 1:1. The isocyanate used as solvent is free from solids and has a hydrolizable chlorine value of less than 2 %.