(hindered isocyanate). An isocyanate derivative that will decompose to an isocyanate upon heating. In one type, phenol is combined with an isocyanate, and the resulting urethane is stable at room temperature but dissociates at 160C to the original phenol and isocyanate. These generators are used commercially in a mixture with a polyester, which can be stored indefinitely but upon heating produces a polyurethane resin.