12.1 Encapsulated biocide ensuring low biocide content in anti-fouling technology

摘要

A silica aerogel encapsulated biocide, eg. zinc pyrithione, can be used in an anti-fouling paint to control the biocide leaching from the paint. Yacht paint formulations with approximately 70 weight-% reduction of biocide, and without pigments/fillers as cuprous oxide and zinc oxide, that may cause long-term adverse effects in the aquatic environment, have been formulated and evaluated. A reduction in cuprous oxide will reduce the raw material cost of an anti-fouling paint, as cuprous oxide currently Is one of the most expensive raw materials in an anti-fouling paint. The test paint formulation has approximately the same technical properties as a commercial solvent-based anti-fouling paint. The gel particles are hydrolysed/worn down throughout the polishing process thus giving a constant effective release of biocide in the coated surface layer. The test paint has during a summer season proven similar anti-fouling efficacy on rafts compared to a commercial product and to show the same effectivity against fouling on yachts in sea water. Technical properties of the gel as a raw material, the wet paint and the anti-fouling paint film are discussed and examples of practical experiences are given. The gel technology, can also be used with other biocides more suitable for large vessels or for other coating applications Acknowledgements: For financial support: The Danish Environmental Protection Agency (DEPA, incl. representatives from the DEPA and industry following the project) As cooperation partners: Kjeld Schaumburg, Roskilde University (Centre for Interdisciplinary Studies of Molecular lnteractions)/CISMI/FiBaC and Bjorn Sivik, Bjarga AB (Both with regard to knowledge on aerogel technology and producing samples on demand) Jesper Hojenvang, Danish Sailing Association (Raft tests in Jyllinge and Horsens harbours etc.) Professor Sergey Dobretsov, Sultan Qaboo's University, Oman (Giving us opportunity to test in Oman) Annika Vaksmaa (Raft tests and fouling reported from Muscat, Oman) Agnete Krabbe Katholm (Raft tests and fouling reported from Sydney, Australia).