In many applications, the highest level of performance is achieved using two-component polyurethane systems. This is the frequently the case for solvent-based and waterborne coatings in addition to adhesives. However, one-component formulations are often preferred, since handling is simpler and it is not necessary to monitor mixing ratios of the isocyanate and polyol. The performance of a two-component coating, on the other hand, will suffer if the formulation is significantly off ratio. For example, if the isocyanate/polyol ratio is under-indexed—meaning there are more equivalents of polyol than isocyanate—the polymer will not achieve the required molecular weight, and properties will be unacceptable.
Blocked isocyanate chemistry may meet your needs for a higher performing, one-component coating formulation. This coating is formulated by mixing a polyol with a blocked isocyanate to produce a blend with room temperature stability. Upon heating, a high-performance coating is obtained: