(163m) Advances in Military Coatings Systems

Military coating systems typically consist of an inorganic pre-treatment, an epoxy primer, and a polyurethane topcoat for the exterior of vehicles and structures. Military coatings systems experience some of the harshest environments, including intense sunlight, corrosive sea water, extreme heat, exposure to fuel, and damage from shrapnel, weapons fire, and collisions. Army coatings not only protect against these environmental hazards, but also must maintain good camouflage (low gloss, etc.) and continue to protect the soldier from chemical and biological attack. Furthermore, the DoD must reduce environmental pollution from coatings systems by eliminating volatile organic compounds (VOC) from the primers and topcoats and eliminating hexavalent chromium (Cr6+) from the pretreatment, while still maintaining high performance. We are attempting to further reduce VOC emissions by moving towards water-based primers and topcoats that contain significantly less VOC content. In addition, the trivalent chromium pretreatment process has had excellent success in reducing corrosion, while not using any Cr6+. Furthermore, multifunctional hyperbranched polymers and nano-particles with biocidal activity are being incorporated into coatings systems to self-decontaminate exposed military equipment or improve the efficacy of current decontamination procedures. The biocidal agents act by diffusing to the surface during coating preparation, where their functional groups, such as quaternary ammonium salts and silver nano-particles, interact with and kill microorganisms and/or catalytically degrade chemical warfare agents. In addition, these multifunctional biocides contain functionality that can chemically react into the coatings to prevent leaching of the chemicide/biocide over time. Furthermore, the self-decontaminating hyperbranched polymers and the environmentally friendly formulations have passed military specification testing.