UV-Curable Polyurethane Dispersions for Aerospace Topcoat Applications

By C. Todd Williams, Katrina Callen, Charles A. Gambino, Michael Dvorchak

Coating application is the rate determining step in aircraft production. Currently, aerospace coatings utilize two-component polyurethane chemistry that requires 72 hours curing time before the plane can be returned to service. UV-curable polyurethane dispersions (UV-PUDs) were evaluated as aerospace topcoats to allow for increased productivity as a result of decreased curing time. UV-PUD based coatings were formulated and evaluated for their ability to meet military topcoat specification MIL-PRF-85285D.

Coatings that meet this specification require a balance of chemical and water resistance, flexibility, weatherability, and aesthetics. This article will focus on the performance of UV-PUD coating formulations with respect to these properties. Aerospace coatings demand a balance of chemical and water resistance, weatherability, flexibility, and aesthetics. Currently, these performance requirements can only be met using two-component aliphatic urethane coatings, which typically require 72 hours to cure before the plane can be moved outside the hangar.

Because of this limitation, ultraviolet-curable coatings have been evaluated as aerospace coatings to decrease the “dry-to-fly” time, thus allowing for increased productivity during refinish and manufacturing.¹

This article will explore the formula-tion and physical properties of UV-curable polyurethane dispersions (UV-PUDs) as alternatives to conventional aerospace coatings.