Process for the production of polyisocyanates of the diphenylmethane series with a reduced color value
AssigneeBayer Aktiengesellschaft
InventorsTorsten Hagen, Friedhelm Kämper, Daniel Koch, Heinz-Herbert Müller
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Abstract
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° C. or neutralizing the reaction mixture from step a) with a base and heating the neutralized mixture to a temperature of more than 110° C., and c) phosgenating the polyamine from step b) to convert it to the corresponding polyisocyanate.
Claims6
Process for the production of a polyamine of the diphenylmethane series comprising
- a) reacting aniline and formaldehyde in the presence of an acidic catalyst to produce a polyamine and
- b) (i) neutralizing the reaction mixture from step a) with a base at a temperature of more than 110° C. or (ii) neutralizing the reaction mixture from step a) with a base and heating the neutralized mixture to a temperature of more than 110° C.
A process for the production of a polyisocyanate of the diphenylmethane series comprising
- a) reacting aniline and formaldehyde in the presence of an acidic catalyst to produce a polyamine,
- b) (i) neutralizing the reaction mixture from step a) with a base at a temperature of more than 110° C. or (ii) neutralizing the reaction mixture from step a) with a base and heating the neutralized mixture to a temperature of more than 110° C., and
- c) phosgenating the polyamine from step b) to produce the corresponding polyisocyanate.
Dependencies are inferred from the claim text.