Process for producing polyisocyanates of the diphenyl methane series having a reduced color value
AssigneeBayer Aktiengesellschaft
InventorsTorsten Hagen, Friedhelm Kämper, Daniel Koch, Rudolf Uchdorf, Stefan Wershofen
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Abstract
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.
Claims6
A process for producing polyamines of the diphenyl methane series comprising
- a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine-containing mixture,
- b) neutralizing the polyamine-containing mixture with a base,
- c) separating the neutralized mixture into an aqueous phase and an organic phase, and
- d) adding a base to the organic phase.
A process for the production of polyisocyanates of the diphenyl methane series comprising
- a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine-containing mixture,
- b) neutralizing the polyamine-containing mixture with a base,
- c) separating the neutralized mixture into an aqueous phase and an organic phase,
- d) adding a base to the organic phase, and separating the polyamine,
- e) phosgenating the polyamine to produce a polyisocyanate.
Dependencies are inferred from the claim text.