Production of mixtures of diisocyanates and diphenylmethane

A method of preparating diisocyanates mixture of the diphenylmethane is disclosed, which comprising mixing the fraction of diisocyanates of the diphenylmethane series containing at least 95 wt. % binuclear methylenediphenyl diisocyanate with mixture having aromatic isocyanates: a) reacting aniline and formaldehyde in the presence of an acid catalyst to produce diamines and polyamines of the diphenylmethane series containing binuclear methylenediphenyl diamine, b) phosgenating the diamines and polyamines produced in a), to produce a crude diisocyanate and polyisocyanate, and c) separating a fraction containing at least 95 wt. % binuclear methylenediphenyl diisocyanate with a 4,4'-MDI content of over 60 wt. %, a 2,4'-MDI content of 4 to 35 wt. % and a 2,2'-MDI content of 0.01 to 10 wt. %, relative to the mass of the fraction, and a maximum of 20 ppm phenyl isocyanate.