Method of forming storage-stable polyurethane prepolymers

Abstract

Abstract Methods of forming liquid, low viscosity, low molecular weight, cross-linkable, stable polyurethane prepolymers which comprise: reacting polyisocyanates, and preferably aliphatic and cycloaliphatic diisocyanates, with polyhydroxy compounds or polyols, and preferably diols, triols, tetrols, and mixtures thereof; the polyols having a molecular weight of from about 62 to about 3000; the polyisocyanates and the polyols being added to the reaction mixture in an NCO/OH ratio in the range of from about 0.7:1 to about 6:1, and preferably from about 1.6:1 to about 4:1; the reaction taking place preferably in an inert, non-reactive organic solvent such as xylene; in the absence of any reaction catalysts, or in the presence of a relatively very low concentration of reaction catalysts of from about 0.00005% by weight to about 0.8% by weight, based on the total weight of the reaction mixture; at a reaction temperature of from about 0 DEG C. to about 70 DEG C., and preferably from about 0 DEG C. to about 40 DEG C., for a reaction time of from about 1/2 hour to about 12 hours; and terminating the reaction short of completion at a percent completion of reaction of from about 2% to about 95%, and preferably from about 30% to about 80%. The resulting liquid, low viscosity, low molecular weight, cross-linkable, stable polyurethane prepolymers are also included in the inventive concept.

Inventors

• 👤 Vincent F. Pogozelski
• 👤 Robert P. Conger

Bibliographic Details