The objective of this project is to demonstrate novel polysiloxane topcoats on the exterior surface of U.S. Navy ships and submarines, then validate their performance compared to MILSpec. qualified topcoats that contain hazardous Oxsol-100 solvent and isocyanate-based molecules.The new polysiloxane topcoat formulations, which will be Oxsol-free, isocyanate-free, and low in VOCs, will be based on non-hazardous raw materials and will be formulated as single- (1K) and two-component (2K) systems. The project will involve of manufacturer scale-up topcoats in multi-gallon quantities, verifying their performance in a laboratory setting in accordance with military specification requirements, demonstrating these new topcoats on in-service surface ships and submarines, and validating they provide equivalent or greater performance compared to currently qualified topcoats.

Polysiloxane topcoats were transitioned by the Naval Sea Systems Command in the early 2010’s to replace the 50-year-old silicone alkyd coating technology that was used to provide camouflage on the exterior of surface ships. These coatings are qualified to MIL-PRF-24635 and have many performance benefits over silicone alkyds, including improved corrosion resistance (two-coat vs. three-coat system), greater color and gloss retention, and improved adhesion to anti-corrosive epoxy primers. The 1K polysiloxane topcoats for ships and submarines are based on novel polymers with a flexible aliphatic backbone and terminal alkoxysilane groups. The 2K polysiloxane topcoats are based on the dual-reaction of epoxy-functional oligomers with amine-functional oligomers, including hydrolysis and condensation of aminoalkoxysilanes to form a cross-linked network. Both the 1K and 2K polysiloxanes are formulated with a unique blend of novel solvents, fillers/pigments, and additives that enable the removal of Oxsol 100 while retaining flash point >100 °F. These formulas also do not require the use of isocyanates to provide highly flexible systems.

 The lifecycle cost of submarine topcoats will be reduced since the polysiloxane topcoats have shown to provide significantly greater color and gloss retention than the polyurethanes qualified to submarine requirements. Finally, implementation of a 1K topcoat for all exterior painting will enable sailors to perform touch-up and repair applications with a topcoat that is user-friendly and generates minimal waste. 

(Anticipated Project Completion - 2025)