Method for producing methylene-diphenylene-diisocyanates and polymethylene-polyphenylene-polyisocyanates

US10947187B2 · kind B2 · utility

Assignee

• Covestro Intellectual Property GmbH & Co. KG · DE

Inventors

• Thomas Knauf · Dormagen, DE
• Peter Plathen · Krefeld, DE
• Dirk Manzel · Moers, DE
• Stefan Wershofen · Mönchengladbach, DE

Key dates

• Filing date: Jan 2, 2019
• Grant date: Mar 16, 2021
• Expiry date: Jan 2, 2039

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C265/14
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a method for producing methylene-diphenylene-diisocyanate and optionally a mixture of methylene-diphenylene-diisocyanate and polymethylene-polyphenylene-polyisocyanate, wherein, in a step α), a fraction (142) containing a methylene-diphenylene-diisocyanate and secondary components is provided, optionally via a step α.1), the separating of methylene-diphenylene-diisocyanate and secondary components from a fraction (100) containing methylene-diphenylene-diisocyanate and polymethylene-polyphenylene-polyisocyanate, and wherein, in a step β), the fraction (142) containing methylene-diphenylene-diisocyanate and secondary components is subjected to a purification comprising an isomer separation by distillation and/or crystallization in two or more sub-steps (a, b, . . . ), obtaining two or more methylene-diphenylene-diisocyanate-reinfractions (140-1, 140-2, . . . ) and a secondary component fraction (150), wherein the secondary component fraction (150) obtained in step β) is returned to one of the sub-steps of step β), wherein none of the methylene-diphenylene-diisocyanate-reinfractions (140-1, 140-2, . . . ) from step β) are obtained as distillation or crystalliz…