2 Summary and conclusions

Glaskeramisk bundmaling til lystbåde

The purpose of the work presented in this report has been to test different Sol-Gel based surface treatments for the application as biofouling inhibiting ship hull paints for smaller vessels (sailboats and power boats). The development and tests were performed in 2007, with the development going on from January to April after which the Sol-Gel coatings were applied on a number of selected pleasure boats. Throughout the sailing season of 2007, the test boats were monitored, both while in daily use and during inspections on land.

The test was based on data and results from a previous project (1), which generated promising data on the use of easy-release Sol-Gel coatings as ship hull paints.

In the present project, two types of coatings were tested, INC-46 and INC-47. Both are technologically and functionally based on the experiences gained from the previously mentioned project. INC-46 was formulated with the purpose of obtaining a hydrolysis and UV stable matrix with excellent easy-release properties. INC-47 was formulated with the purpose of obtaining a hydrolysis and UV stable matrix with excellent biofouling inhibiting properties. Both coating systems have been formulated to facilitate application with both brush/roll and spray. Likewise, both systems cure at temperatures that would be expected under relevant circumstances

Furthermore INC-46 has been embedded with copper and silver nanoparticles to attain a biostatic effect. In a series of experiments with biofouling, this functionalization has resulted in significant biofilm inhibiting effect.

The purpose of the present investigation has been:

To test two selected coating systems for:

General applicability as ship hull paint
- Application properties
- Curing properties
- Adhesion
- Hydrolysis stability
- UV stability
Specific ship hull paint properties:
- Easy-release properties
- Antifouling properties

Conclusions

Through the development and tests, a number of valuable data have been obtained on the selected coating systems and their properties as antifouling ship hull paints. These data will serve as the foundation for further developments aimed at formulating antifouling coatings (both with regard to maritime fouling and with regard to anti algae, anti bacteria or anti fungal coatings).

With regard to the general applicability as ship hull paint, it can be concluded that the applied coating systems exhibit excellent basic properties with regard to application, curing, adhesion, hydrolysis stability and UV stability.

The application properties were judged by the personnel responsible for the application, and as a whole the feedback was very positive, though there were expressed wishes for a higher viscosity. During the subsequent inspections, it was possible to conclude that adhesion, hydrolysis stability and UV stability were excellent. Only on minor spots on one boat, less than optimal substrate adhesion was observed. This observation could be explained by inferior preparation of the hull prior to coating, as the boat had previously been used for testing a silicone based ship hull paint.

With regard to the specific ship hull paint properties, it can be concluded that the tested coating systems have not lived up to the expectations in regard to prevention of maritime fouling. It has thus been possible to observe fouling, in varying degrees, on the tested areas of the ship hulls. Ordinary sailing has not been sufficient to wear down the fouling, explaining why the fouling during the season reached a substantial amount. Tests for easy-release properties of the coated areas only shows a moderate improvement compared to untreated areas.

In parallel with the testing of the glass ceramic coating systems from Danish Technological Institute, three ship hull paints were tested:

Coatzyme from Biolocus (commercially available)
Nanocover marine sealing from Nanocover (commercially available)
Ecomarine (not commercially available)

None of the tested ship hull paints possessed maritime fouling inhibiting properties that could match that of the reference ship hull coating system.