Bayer Aktiengesellschaft

Friedhelm K&auml;mper

Torsten Hagen

Daniel Koch

Stefan Wershofen

Rudolf Uchdorf

Heinz-Herbert M&uuml;ller

Polyisocyanates of the diphenylmethane series are produced by a) reacting aniline and formaldehyde in the presence of an acidic catalyst to produce a polyamine, b) neutralizing the reaction mixture from step a) with a base at a temperature of more than 110&deg; C. or neutralizing the reaction mixture from step a) with a base and heating the neutralized mixture to a temperature of more than 110&deg; C., and c) phosgenating the polyamine from step b) to convert it to the corresponding polyisocyanate.

Process for the production of polyisocyanates of the diphenylmethane series with a reduced color value

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.

Growing community of inventors

Krefeld, Germany

Friedhelm Kämper

Growing community of inventors

Krefeld, Germany

Friedhelm K&auml;mper

Friedhelm Kämper