Process for preparing polyisocyanates

US10112892B2 · kind B2 · utility

Assignee

• Covestro Deutschland AG · DE

Inventors

• Jürgen Arras · Itzehoe, DE
• Jan Busch · Düsseldorf, DE
• Christian Steffens
• Dietmar Wastian · Dormagen, DE
• Manfred Keller-Killewald · Wasserburg am Inn, DE
• Holger Conzelmann · Lichtenwald, DE

Key dates

• Filing date: Jun 27, 2016
• Grant date: Oct 30, 2018
• Expiry date: Jun 27, 2036

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C263/10
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to a continuous process for preparing a polyisocyanate, in which a polyamine and phosgene are first converted predominantly to carbamoyl chloride and amine hydrochloride and only in minor proportions to polyisocyanate, and a portion of the carbamoyl chloride- and amine hydrochloride-containing reaction mixture thus obtained is recycled into the reaction with phosgene, wherein polyamine, phosgene and the carbamoyl chloride- and amine hydrochloride-containing reaction mixture are mixed intimately in a mixing unit. The portion of the carbamoyl chloride- and amine hydrochloride-containing reaction mixture which is not recycled into the phosgenation is worked up to give the polyisocyanate.