PROCESS FOR PURIFYING MIXTURES COMPRISING 4,4'-METHYLENE DIPHENYL DIISOCYANATE

摘要

The invention relates to a process for purifying mixtures comprising 4,4'-methylene diphenyl diisocyanate, comprising the distillative purification of a mixture I comprising 4,4'-methylene diphenyl diisocyanate by means of a column K1, wherein the gaseous stream consisting of mixture I is contacted in column K1 with at least one liquid compound A which has a boiling point which is the same as or higher than 4,4'-methylene diphenyl diisocyanate, and wherein the gaseous stream O which is obtained at the top of the column and comprises 4,4'-methylene diphenyl diisocyanate is cooled to a temperature of 20°C to 60°C within not more than 5 seconds.