Process for separating polyurethane hydrolyzates into polyether and diamine

US4399236A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Georg Niederdellmann · Dormagen, DE
• Norbert Roemer · Wittlich, DE
• Jurgen Schenk · Dresden, DE
• Hartmut Hetzel · Cologne, DE
• Ernst Grigat

Key dates

• Filing date: Sep 4, 1981
• Grant date: Aug 16, 1983
• Expiry date: Sep 4, 2001

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02W30/62
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

The present invention is directed to a process for separating polyurethane hydrolyzates, preferably polyurethane foam hydrolyzates, into substantially amine-free foamable polyethers and diamines, comprising (a) (i) briefly expanding a hot polyurethane hydrolyzate obtained in a continuous screw extruder to normal pressure or in vacuo and, without using readily volatile components (ii) spraying said hydrolyzate directly into a tubular coil evaporator which is heated to 180.degree.-300.degree. C. and at the end of which a pressure of from 0.1 to 20 mbar is applied and (iii) separating a hydrolyzate containing less than 1% by weight of NH.sub.2 in a following cyclone from most of the diamine evaporated and all the solvent used, the diamine being separated from the solvent used in a following distillation column, optionally without any further heat input; (b) precipitating any diamine still present quantitatively in the form of its hydrochloride by introducing excess hydrogen chloride into the hydrolyzate, optionally diluted with inert solvents; and (c) the regenerated polyether obtained after removal by filtration of the precipitated amine salt being freed under reduced pressure from i…