Process for the production of soluble high molecular weight polyurethanes which are free from isocyanate groups

US4039516A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Georg Niederdellmann · Dormagen, DE
• Henning Klussmann · Rommerskirchen, DE
• Horst Conrad

Key dates

• Filing date: Apr 7, 1976
• Grant date: Aug 2, 1977
• Expiry date: Apr 7, 1996

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G18/0852
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

This invention relates to an improved process for the production of high molecular weight polyurethanes which are free from isocyanate groups and are soluble in organic solvent in reduced reaction times. The reactants, polyol and isocyanate, for example, are mixed together with solvent and the temperature is permitted to rise under the effect of the heat of reaction. The reaction mixture is then cooled with solvent addition in such a way that the viscosity of the reaction mixture remains constant until the optimum temperature for the polyurethane formation reaction ("specific reaction temperature") is reached. The mixture is then gradually cooled until there is no residual isocyanate present and the polymer is recovered from the reaction mixture.