Process for the production of polyisocyanates

US4745216A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Berthold Keggenhoff · Krefeld, DE
• Gunther Ellendt · Krefeld, DE
• Marcel Petinaux · Krefeld, DE
• Alfred Mitschker · Odenthal, DE
• Peter M. Lange · Leverkusen, DE

Key dates

• Filing date: Mar 25, 1985
• Grant date: May 17, 1988
• Expiry date: Mar 25, 2005

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C263/20
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Polyisocyanates are produced by reacting a polyamide solution with a phosgene solution. After the product polyisocyanate has been recovered, the solvent or a portion of the solvent employed is treated with crosslinked polymers insoluble in the solvent which polymers contain primary and/or secondary alcoholic hydroxyl groups and/or primary and/or secondary amino groups. After treatment, the polymer and any reaction products are removed. The solvent may then be reused. Preferred solvents are chlorobenzene and o-dichlorobenzene. The preferred polymers are bead polymers or bead copolymers of (meth)acrylic acid or styrene/divinyl benzene copolymer.