Ready-to-use ingredients require no other compounding
Polyisocyanates yield prepolymers used in solventborne coatings
Solventborne one-component (1K) and two-component (2K) polyurethane systems are used across a broad array of industrial applications, from automotive refinishes and coatings for aircraft and railcars, to plastics and corrosion protection, as well as wood and furniture finishes.
The properties of moisture-curing 1K coatings are determined by the nature of the particular isocyanates used. Coatings based on aliphatic polyisocyanates, for example, generally need longer drying times than those based on aromatic polyisocyanates. Drying times are not only dependent on the temperature, but also on the amount of atmospheric moisture present.
One-component systems generally cure at a wide range of temperatures. Coatings based on polyisocyanates or on NCO-functional prepolymers harden at room temperature. Those based on blocked NCO prepolymers may require baking at temperatures up to 180°C.
Weathering properties of 1K coatings also largely depend on the type of isocyanate used. Coatings based on TDI- or MDI-polyisocyanates have a tendency to yellow in the light and display a relatively rapid loss of gloss on weathering. Those based on HDI, IPDI and Desmodur® W (H12MDI) are light stable.
Two-component polyurethane systems dry relatively quickly without exposure to heat due to their reactive NCO groups. In some applications these systems are force-dried at up to 80°C or baked at temperatures above 120°C to yield shorter curing times. This results in faster production cycles and increased efficiency.
A total of
Product Overview, Products for reaction with polyisocyanates