UNDERWATER ODYSSEY

Ensuring that paints and coatings are eco-friendly is a priority for manufacturers, as recent advances illustrate

Effective anti-fouling of vessels has always been a key element in improving the performance and therefore costs of operating vessels and there have been a number of advances by specialist companies in this respect.

For example, I-Tech’s research and development team’s efforts enhance the power of Selektope in biocidal antifouling coatings while opening up new route into foul release coatings.

Over the past five years, I-Tech’s scientists have discovered new ways in which 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 has enhanced the performance of the technology in self-polishing co-polymer (SPC) marine coatings by improving the dispersion of the active substance. 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, nonmetal 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 reesearch and development efforts in the past few years have focused on further improving controlled release.

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 on to 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 has obtained proof of concept that if Selektope is pre-adsorbed on a carrier compound, in this case zinc oxide , 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.

Also studied was 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.

Markus Hoffmann, technical director at I-Techm 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.”

GIA expansion

Two companies have become the newest members of The Global Industry Alliance (GIA) for Marine Biosafety –Armach Robotics and Jotun.

Armach Robotics, an in-water cleaning service provider, and Jotun, which manufactures coatings, join at the end of a busy year for the GIA.

Jotun will bring experience in antifouling coating technology, proactive in-water cleaning services and innovations in biofouling management.

Petter Korslund, regulatory affairs manager for Jotun, says: “GIA is an important industry initiative to work together and co-operate towards a more sustainable shipping industry. As a global leader in maritime coatings and clean hull solutions, it is our mission to contribute to cleaner hull on vessels, enabling the shipping industry’s ambition for decarbonisation and biodiversity.”

Armach Robotics will add to the Alliance’s discussions and work, bringing its perspective of in-water cleaning services. Karl Lander, director - regulatory compliance and outreach at the firm, says: “Armach is excited to work with GIA and its partners on addressing the negative impact biofouling has on the global shipping industry.”

GIA is an initiative of the International Maritime Organization’s GloFouling Partnerships project. It brings together private sector companies from a wide range of ocean-based industries, such as shipping, offshore oil and gas, technology research and fouling control systems manufacturers, including antifouling coatings, in-water cleaning systems, BioPass, filtration systems and ultrasonic.

Together, these respective sectors work towards sustainable and practical solutions that can facilitate the implementation of biofouling management regulations.

Biofouling is the accumulation of micro organisms, plants, algae, or small animals on ships’ hulls and other wetted surfaces. It can create irreversible effects on marine biodiversity by introducing potentially invasive aquatic species into new environments. Biofouling also increases the drag of ships, forcing them to burn more fuel to maintain speed, thus contributing to higher greenhouse gas emissions.

The GIA has also published two reports on various aspects of biofouling.

The first analyses the impact of ships’ biofouling on greenhouse gas (GHG) emissions. It found that keeping ships’ hulls free from just a thin layer of slime could reduce a ship’s GHG emissions by 25%.

The second study compares current and emerging regulations and practices for biofouling management.

In addition, the GIA has also released a short animation video to increase awareness of GHG and good biofouling management.

Sea Zero gets underway

Paint manufacturer Jotun is one of the partners in the Sea Zero project Hurtigruten Norway started in spring 2022, with the aim of enabling zeroemission passenger and freight transport along the Norwegian coast by 2030.

Together with 13 partners, Hurtigruten has been granted NOK 67m from Grønn Plattform, which contributes