New Low-Viscosity Acrylic-Urethane Prepolymers and Their Acrylated Oligomers for Moisture and UV-Curable Coatings

By Daniel B. Pourreau, Scott Smyth

This article describes a new class of urethane acrylate oligomers for weather­able UV-curable systems. Unlike commercial urethane acrylates that are based on polyether or polyester polyols, this new class of urethane oligomers is based on acrylic polyols. These new acrylic polyols are unique in that they produce low-viscosity, nongelling urethane prepolymers with isophorone diisocyanate.

These prepolymers can be further treated with hydroxy-functional acrylates such as hy­droxyethylacrylate (HEA) or caprolactone acrylate (CA) to yield low-viscosity acrylated urethane acrylic oligomers.By replacing the polyester and polyether backbone in urethane acrylates with an acrylic backbone, this chemistry opens the door to more weatherable UV-cur­able coatings, with properties that approach two-component urethane systems.

These new urethane acrylates were formulated into sprayable UV-curable coat­ings with properties that rival two-component urethanes. The influences of dilu­ent monomer type and content, hydroxy acrylate, and solvents on coating viscos­ity, VOC content, and properties were evaluated.