SBIR-STTR Award

The Navy has a need for passive non-toxic anti-fouling (AF) coatings to reduce or eliminate biofouling on ship hulls without the need for external activation and without leaching harmful biocides into the surrounding environment. Furthermore, the coatings need to be easily applied and provide a long operational lifetime (>5 years), while remaining environmentally benign. Prior attempts at preventing marine biofouling have relied heavily on toxic AF coatings, which release copper, tin, or organic biocides into the surrounding water. Recent restrictions led to the development of foul release coatings (FRCs) as non-toxic alternatives, which minimize the adhesion of marine foulers on their surface. Texas Research Institute Austin, Inc. will develop broad-spectrum AF amphiphilic silicones and polyurethanes containing a proprietary surface modifying additive (SMA). The coatings do not require a tie coat, cost approximately the same as copper-based paints, and are about half the cost of commercially available FRCs (Intersleek 1100SR). They are easily synthesized and can be applied by conventional means. When they come into contact with water the surface rapidly restructures (~3 min) and becomes highly lubricative. Furthermore, the coating has undergone static testing in the Atlantic (20 weeks) and Indian Oceans (16 weeks) resulting in negligeable biofoul coverage.

Benefit:
The benefits of this project to the Navy are: a) the complete mitigation of all biofouling that would normally occur without the application of the proposed coating, b) improved fuel efficiency (>10%) of naval vessels due to the lubricating effect of the coating surface when it comes into contact with water, and c) the cost savings due to reduced downtime for spraying/scrubbing and increased time between maintenance events. Finally, an epoxy tie coat/primer will not be required for the proposed surface modifying additives (SMA)-modified coatings and therefore, the required man-hours for application and material cost will be significantly reduced. The use of this simple, yet novel, coating will significantly improve the anti-fouling performance of not only US Navy and Coast Guard ships, but also commercial vessels and offshore energy platforms. Furthermore, the coating can be easily applied to a desired thickness with conventional methods (rolling, brushing, dip casting, spray casting, etc.) and should provide significant cost savings in terms of improved fuel consumption due to the formation of a lubricating surface layer. The commercial applications include coatings for DoD (destroyers, amphibious assaults, aircraft carrier, combat ships, submarine, and cutters) and commercial maritime vessels (container ships, cruise liners, fishing boats), private maritime vessels (yachts, sailing boats, jet skis), buoys with attached sensors in remote locations, underwater cabling, underwater piping, and offshore operations where biofouling and/or corrosion are a problem (wind turbines, oil rigs, drilling, surveillance, etc.).

Keywords:
Non-toxic, Non-toxic, polyurethane, Marine, silicone, coating, Anti-Fouling, corrosion, Ship hull

The Navy currently has a need for passive solutions to mitigate biofouling on ship hulls that are not externally activated and do not leach harmful biocides into the environment. The fouling of ship hulls is a serious and persistent problem that increases drag, which leads to increased fuel consumption. This necessitates periodic maintenance whereby the ships are docked and their hulls are scrubbed to remove any adherents. Therefore, TRI Austin will work with TAMU to use a previously developed in-house broad-spectrum anti-fouling silicone that contains a surface modifying additive (SMA) and integrate the SMA into an in-house polyurethane coating. The coatings are easily synthesized and applied to various substrates, but more importantly, cure when in contact with water while the surface restructures and becomes lubricative. Furthermore, the coating does not need a tie coat, in contrast to U.S. Navy Standard Coatings, and has undergone static testing in the Atlantic (20 weeks) and Indian Oceans (16 weeks) resulting in negligeable biofoul coverage when compared to a copper standard. In conclusion, the coating is low cost, easily synthesized and applied, will completely remove the need for scrubbing the hull while docked, and will reduce the drag coefficient, resulting in improved fuel consumption.

Benefit:
The benefits of this project to the Navy are: a) the complete mitigation of all biofouling that would normally occur without the application of the proposed coating, b) improved fuel consumption due to the lubricative effect of the coating surface when it comes into contact with water, and c) the cost savings due to: reduced downtime or elimination of scrubbing and increased time between maintenance events. For ship hulls and additional maritime surfaces, a tie coat on the desired substrate will no longer be required, thereby eliminating additional cost in terms of material volume and man-hours. The use of this simple, yet novel, coating will significantly improve the anti-fouling performance of not only Navy ships, but any marine vessel/structure that is in constant contact with water. Furthermore, the coating can be easily applied to a desired thickness with conventional methods (dip casting, spray casting, etc.) and should provide significant cost savings in terms of improved fuel consumption. The commercial applications include coatings for DoD and commercial maritime vessels, sport maritime vessels, bouys with attached sensors in remote locations, underwater cabling, underwater piping, and offshore operations where biofouling and/or corrosion are a problem (oil rigs, drilling, surveillance, etc.).

Keywords:
polyurethane, Non-toxic, Polyurea, Antifouling, Tough, passive, Broad Spectrum, silicone