Abstract: The disclosed one-part curable polyurethane prepolymer compositions comprise a continuous phase and, distributed uniformly through this phase, a discontinuous phase containing a polyol curing agent of the pentaerythritol type. At moderately elevated temperatures, the polyol phase begins to enter into a curing reaction which has a single exotherm peak. The prepolymers are made from aliphatic or cycloaliphatic polyisocyanates and polymeric polyols. The one-part curable system is stable for long periods at room temperature. The curable polyurethane systems can be used in adhesives, coatings, sealants, and similar applications.

Abstract: A one-package heat curable polyurethane composition, comprising an isocyanate terminated prepolymer liquid phase and a separate solid polyhydroxy compound phase insoluble in the prepolymer phase, and suitable for use as an adhesive. The liquid prepolymer phase comprises the reaction product of an aromatic polyisocyanate and a polyhydroxy compound. The separate insoluble solid polyhydroxy compound phase is dispersed or suspended throughout the liquid prepolymer phase and remains separate until heat cured. The ratio of OH groups in the solid polyhydroxy compound phase to NCO groups in the isocyanate terminated prepolymer liquid phase is less than 2:1. The one-package polyurethane adhesive composition can also be useful as an in-mold coating and an injection molding compound.