Basf Corporation

Paul Jacobs

Bernd Bruchmann

Dietrich Scherzer

Roland Minges

Peter Keller

Wolfgang Heider

Bernhard Otto

Siegmund Pohl

Wilfried Seyfert

Willy Van Pee

Mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (raw MDI) having a reduced iodine color number and a reduced chlorine content are prepared by reacting the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, and then, after phosgenation is complete, incorporating into the reaction mixture, in the presence or absence of the phosgene, a mixture of water and at least one monohydric or polyhydric polyoxyalkylene alcohol, preferably having a functionality of from 2 to 3, and advantageously having a hydroxyl number of from 20 to 1800, in an effective amount which advantageously comprises from more than 0.01 to 0.3% by weight of water (i) and from 0.5 to 5% by weight of a polyoxyalkylene alcohol (ii), in each case based on the weight of raw MDI, then removing the excess phosgene or the phosgene residues still present and the inert organic solvent, if desired adding to the reaction product up to 5% by weight, based on the weight of raw MDI, of at least one antioxidant based on phenol and/or aryl phosphite and thermally treating the reaction mixture.

Preparation of mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a reduced iodine color number and a reduced chlorine content

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Munich, Georgia

Paul Jacobs