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

US6229043A · kind A · utility

Assignee

• BASF SE

Inventors

• Dietrich Scherzer · Neustadt, DE
• Bernd Bruchmann · Ludwigshafen, DE
• Roland Minges · Havelsee, DE
• Peter Keller · Bruchmühlbach-Miesau, DE
• Willy van Pee · Neukirchen-Vluyn, DE
• Wolfgang Heider · Neustadt, DE
• Siegmund Pohl · Ludwigshafen, DE
• Bernhard Otto · Schifferstadt, DE
• Paul Jacobs · Holsworthy, GB
• Wilfried Seyfert · Bad Dürkheim, DE

Key dates

• Filing date: Jun 26, 1996
• Grant date: May 8, 2001
• Expiry date: Jun 26, 2016

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G18/8019
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

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 treatin…