Process for the preparation of viscosity stable polyurethane solutions

US4530990A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Reinhard Halpaap · Odenthal, DE
• Josef Pedain · Cologne, DE
• Wilhelm Thoma · Leverkusen, DE
• Jurgen Grammel · Cologne, DE

Key dates

• Filing date: Oct 8, 1982
• Grant date: Jul 23, 1985
• Expiry date: Oct 8, 2002

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G18/10
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process is described for the preparation of predominantly linear polyurethane solutions which comprises PA0 (a) reacting PA2 (A) an organic diisocyanate or diisocyanate mixture optionally containing small portions of a triisocyanate with PA2 (B) one or more polyhydroxyl compounds which are predominantly bifunctional and generally have molecular weights of from about 400 to 5000 and PA2 (C) optionally one or more chain lengthening agents having at least two isocyanate reactive hydrogen atoms and molecular weights of from about 32 to 399, PA0 wherein the proportion of isocyanate groups to the number of isocyanate-reactive hydrogen atoms is in the range of from about 0.9:1 to 1:0.9, and PA0 (b) when the polyurethane formed has reached the required viscosity, adding a monofunctional, low molecular weight oxime having a molecular weight of from about 73 to 325, preferably butanone oxime, to the reaction mixture as chain breaking agent in a quantity equivalent to or in excess of the equivalents of unreacted isocyanate groups. The new chain breaking agents are simple compounds which effect rapid chain breaking and have no undesirable side effects as regards subsequent breakdown of the c…