I-Tech R&D efforts enhance power of Selektope® in biocidal antifouling coatings while opening up new route into foul release coatings

22 Dec 2022. By Catherine Austin

Over the past five years, I-Tech’s team of R&D scientists have discovered new ways in which the first-of-its-kind biocide, Selektope® can be introduced to marine antifouling coatings in combination with other biocides with little or no effect on formulation chemistry or performance.

I-Tech AB, developers of the antifouling biotechnology, Selektope® have enhanced the performance of the technology in self-polishing co-polymer (SPC) marine coatings by improving the dispersion of the active substance via adsorption to paint pigment particles. Positive static test results have also provided proof of concept that Selektope can be used in silicone-based foul release coatings, a new application area for the technology.

Selektope is an organic, non-metal biocide that prevents hard fouling. It repels barnacle larvae from a coated surface with non-lethal effect using a novel, biotechnological approach achieved by the active agent medetomidine. Through natural receptor stimulation, the swimming legs of barnacle larva kick at a higher frequency so that they cannot attach to the coated surface.

Traditionally, Selektope is supplied in powder form for direct introduction to a paint batch during the production process. It can also be dissolved in solvent in-situ and then added to a paint batch in solution. Although the controlled release of Selektope in SPC coatings has proved successful using traditional methods with multiple products commercialised to-date, I-Tech R&D efforts in the past few years have focussed on further improving the controlled release of the technology and minimising any issues catalysed through the introduction of Selektope into a paint matrix.

Silyl acrylate SPC coatings are generally sensitive and gelation and instability problems can arise if the paint products are stored for too long. Gelation in SPC coatings creates issues during the application process since paint with a higher viscosity can clog up the tip of the spraying nozzle, resulting in the paint not being sprayed well, or even at all. If the paint is thinned to make it easier to spray onto a surface, it may no longer have the right properties, which could influence the general performance of the coating.

Following two years of R&D work, I-Tech have obtained proof of concept that if Selektope is pre-adsorbed on a carrier compound, in this case zinc oxide (ZnO), prior to being introduced to a paint matrix, the process of gelation is slowed, and the in-can stability of the silyl acrylate paint is improved. Also, antifouling performance is improved, owing to the improved dispersion of the biocide in the paint matrix.

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An additional proof of concept was obtained by the I-Tech R&D team for the addition of Selektope to silicone-based foul release coatings via pre-adsorption on zinc oxide. If Selektope is not properly incorporated into a foul release coating matrix it will leach to the surface of the coating too fast. To-date, this has inhibited the use of Selektope in this antifouling coating type. Static panel testing conducted off the west coast of Sweden has yielded strong, positive results and R&D efforts in this field of research are ongoing.

Test results showed that whereas undamaged foul release coatings are generally efficient at preventing fouling, damaged areas in foul release-coated surfaces are at high risk of biofouling accumulation. This demonstrated that damaged foul release coating surfaces need additional biocidal protection against fouling.

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Dr Markus Hoffmann, Technical Director at I-Tech comments: “This work is significant for two reasons; enhancing the current use of Selektope in SPC coating types and, opening up new routes for us to explore the use of this novel technology in foul release coatings. The fact that the addition of Selektope, pre-adsorbed on pigment particles does not require fundamental paint reformulation makes this R&D progression even more impactful since it can be adopted immediately by our customers. Our next steps will be to expand our knowledge base. We will also conduct further work to refine the process of adsorbing Selektope on zinc oxide and explore other pigments as potential carriers.

Download the technical paper below

Catherine Austin
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