Bayer Materialscience Ag

Covestro Deutschland Ag

Bayer Intellectual Property Gmbh

Heinz-Herbert Müller

Stefan Wershofen

Fritz Pohl

Richard Adamson

Hans-Georg Pirkl

Ulrich Liman

Udo Wolf

Stefan Grabowski

Jeffrey Bolton

Knut Sommer

Rudolf Uchdorf

Jochen Mahrenholtz

Martin Schiffhauer

Robert Vieler

Martin Gerlach

Ralf Echterhoff

Arnulf Werner

Jeffrey S Bolton

Stefan Dresely

Johannes Schweer

Andrea Wimschneider

Stephan Ehlers

The present invention relates to a process for producing diamines and polyamines of the diphenylmethane series (MDA) by reacting aniline and formaldehyde in the presence of an acid catalyst, wherein the aniline contains in total less than 0.5 wt. %, based on the total weight of aniline, of one or more compounds which contain at least one carbonyl group or of one or more compounds that are formed by reaction of these compounds which contain at least one carbonyl group with aniline.

Process for producing diamines and polyamines of the diphenylmethane series

The invention relates to a method for determining the isomer composition in an isocyanate isomer mixture, wherein a spectrum of the isomer mixture is recorded and the spectrum is entered into a chemometric calibration model.

Method and device for determining the isomer composition in isocyanate production processes

The invention provides an improved process for preparing diamines and polyamines from the diphenylmethane series by reacting aniline and formaldehyde in the presence of an acid catalyst, the improvement involving the aniline containing less than about 3 wt. % of diamines and polyamines from the diphenylmethane series, based on the weight of the aniline.

Process for preparing diamines and polyamines from the diphenylmethane series

The invention relates to a process for the production of di- and polyisocyanates of the diphenylmethane series and mixtures thereof, in which aniline and formaldehyde are reacted in the presence of an acid catalyst to form di- and polyamines of the diphenylmethane series; the di- and polyamines of the diphenylmethane series are phosgenated, optionally in the presence of a solvent, to obtain a crude di- and polyisocyanate; from the crude di- and polyisocyanate, at least one fraction containing at least 5 wt. % 3-ring and multi-ring MDI and at least one fraction containing at least 95 wt. % 2-ring MDI are separated by distillation, and the acidities of the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt. % 2-ring MDI are determined analytically; and an acidic compound is added to the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt. % 2-ring MDI, so that the desired acidity is achieved.

Production of di- and polyisocyanates of the diphenylmethane series with defined acidity

The present invention relates to a process for the preparation of di- and polyamines of the diphenylmethane series, and to the preparation of di- and poly-isocyanates of the diphenylmethane series from these di- and poly-amines. The di- and poly-amines of the diphenylmethane series are prepared by the reaction of aniline and formaldehyde in the presence of hydrochloric acid. In with the present invention, the hydrochloric acid employed contains less than 0.001 wt. % of metal ions which are divalent and/or more than divalent.

Process for the preparation of di- and polyamines of the diphenylmethane series

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Krefeld, Germany

Heinz-Herbert Müller