Process for producing polyisocyanates of the diphenyl methane series having a reduced color value

The invention relates to a process for producing polyamines of the diphenyl methane series and to a process for producing polyisocyanates of the diphenyl methane series having a reduced color value obtained by reacting the corresponding polyamine with phosgene. Polyisocyanates of the diphenyl methane series having reduced color values are obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine, b) neutralizing the reaction mixture containing polyamine with a base, c) separating the neutralized mixture into the aqueous and the organic phases, d) adding a base to the organic phase and then e) phosgenating the resulting polyamine to produce the corresponding polyisocyanate.