POLYURETHANES USEFUL AS ENGINEERING PLASTICS

Polyurethane resins are described having high impact strength and other structural strength properties, and significantly improved resistance to deformation by heat. The properties of these materials are such as to make them comparable to engineering thermoplastics such as nylon and like materials commonly used to fabricate structural components such as automotive parts, equipment housing, sporting goods, furniture, toys, household and like consumer goods. The resins are prepared from organic polyisocyanates, an isocyanate-reactive material (polyol, polyamine, etc.) having an average functionality of at least 1.9, a Tg less than 20 DEG C. and molecular weight of 500-20,000, and one or more low molecular weight extenders the major distinguishing feature being the markedly lower proportion by weight (2 to 25 percent) in which the isocyanate-reactive material is employed as compared with polyurethane resins conventionally prepared in the art. Depending upon the particular combination of reactants employed the polyurethanes of the invention can be thermoplastic or thermoset and can be prepared in both cellular and non-cellular form.