Polyurethanes made from blends of polypropylene oxide polyols and polyol intermediates based on organic silicone block copolymers.

摘要

A urethane sealant or coating composition is made from a physical blend of a polypropyleneoxide polyol intermediate and an organic-silicone block copolymer based polyol intermediate. The urethane prepolymer is made by reacting the physical intermediate blend with a polyisocyanate and preferably blocking the same with blocking agents such as phenols to prevent reaction with moisture in the air. Cure is effected through the utilization of curing agents such as polyamines or polyimines, for example, diamines, amine terminated polyethers, ketimines, aldimines, and the like. The sealant composition can contain various fillers, organosilanes, and the like. The prepolymers of the present invention generally have improved elongation and reduced modulus. Either a one-part or a two-part system can be utilized.