Custom Polyurethane Coating Formulations

Two-component polyurethanes are available in both water- and solvent-based systems. They combine Part A (an acrylic, polyester, or polycarbonate resin) with Part B (a catalyst or hardener).

The chemical reaction that occurs when components A and B are mixed is called crosslinking, defined as the process of joining two polymer systems to form a strong molecular structure through covalent bonds. This bond is stronger and more durable than in one-component (1K) systems, giving two-component polyurethanes superior strength and performance.

2K polyurethanes, once catalyzed, apply like other liquid coatings of normal viscosity. Application is typically done by all methods of air spray, including conventional, airless, and electrostatic. Small quantities can be mixed volumetrically by hand in cup guns or pressure pots. Unused material will gel and become unusable, so only mix what can be applied within the coating’s pot life as specified in its product data sheet (PDS). Higher-volume or continuous applications require plural-component mixing and metering equipment, which precisely combine the A and B components at the spray gun. This accurate mixing not only improves color and coating consistency but also eliminates the issues associated with small-batch mixing, including limited pot life.

Once applied, 2K polyurethanes are often cured in a low-temperature force-dry oven, which accelerates the drying process. For parts too large for an oven, the polyurethane can air dry at normal temperature and still achieve the same performance properties as if it were force-dried.