Marine-coatings manufacturers and users must campaign for the continued use of copper-based antifouling materials and seek to avert a sequel to the scenario that is likely to sink the use of tin-based antifouling agents due to environmental concerns.

That was a dominant theme sounded at the National Paint & Coatings Association’s recent Marine and Offshore Coatings Conference in Virginia Beach, VA. Representatives of major marine-coatings manufacturers, joined by suppliers of copper-containing biocidal antifouling agents used in those paints, warned that moves to restrict the use of copper-containing paints would torpedo the ability to protect hulls of ocean-going vessels from attack by marine organisms. Such “fouling” organisms can adversely affect the performance of ships by creating “drag” when vessels are underway, and also add significantly to ship-maintenance costs.

The marine industry is faced with the impending demise of tin-based antifouling agents, long a key weapon in the battle against fouling organisms, due to the materials’ toxicity to “non-targeted” marine life. An international agreement to end the use of tin-based materials is making its way through the multi-national negotiation process, and industry representatives anticipate a ban will be in effect before the end of this decade. That leaves marine-coatings manufacturers and users with copper-containing agents as the most effective ingredient in antifouling paints, industry insiders say.

At the NPCA conference, representatives of three major marine-coatings producers — Ameron International Corp., Akzo Nobel and Sigma Coatings — all agreed that the use of copper-based materials should be a priority for coatings manufacturers and users. They were joined by suppliers of copper antifouling additives, who maintained that there is no scientific evidence that such materials cause harm to non-targeted marine life.

The current thinking of coatings producers was effectively summarized by Jim McCarthy of Ameron, one of several participants in a panel discussion on antifouling coatings that concluded the three-day conference. McCarthy said Ameron is generally pursuing a “three-track” strategy in its marine-coatings R&D efforts:

  • In the short term, the development of marine paints that offer low-level, controlled release of biocidal agents over extended periods. Formulators also are focusing on maximizing the use of copper-based agents in combination with non-metallic co-biocides.

  • In the longer term, the development of “non-stick” or foul-release coatings that do not rely on metallic antifouling agents to repel marine organisms from attaching to ship hulls. Such coatings have been found to work in certain limited applications, but their long-term durability is not proven.

  • A longer-term goal of developing “novel” materials and approaches, including the use of “naturally derived” antifouling ingredients that inhibit the growth of organisms on ship hulls. Also included in the definition of “novel” approaches are non-coating methods such as ultrasonic and electrochemical mechanisms.

    “There are certainly areas that deserve investigation,” McCarthy said. “However, I believe they are further down the road.” In the near term, the most realistic objective for coatings producers, he said, is the optimization of existing technologies. “The development of low leach-rate coatings is really of primary importance,” he said, referring to the controlled release of biocidal agents that repel fouling organisms.

    McCarthy said cuprous oxide — a commonly used copper-based antifouling agent for marine coatings — remains a key formulation ingredient, and he said the development of more environmentally acceptable coatings is crucial to ensuring the continued use of cuprous oxide in the future. Thus the emphasis on optimization on paint formulations — termed “delivery systems” — that generate a low-dose release of biocide over long periods.

    Akzo Nobel’s John Kelly and Sigma’s Dan Robbins, two other participants in the panel discussion, expressed similar views about the direction of marine-coatings development. All agreed that the continued use of copper-containing agents is made even more important due to the cost and time required to come up with alternative technologies. Development of even one such alternative can require an investment of millions of dollars and as long as 10 years to run the gauntlet of regulatory approvals, they pointed out.

    Kelly said coatings manufacturers are devoting considerable R&D efforts to the development of an alternative type of antifouling approach that would rely on low-surface-energy coatings such as silicone-containing paints. These materials are designed to inhibit the accumulation of fouling organisms by causing the organism to detach — essentially slip off — when a vessel is underway. But he also said the continued use of copper-based antifouling additives remains a top priority.

    Robbins said Sigma currently offers one coating product that represents an alternative to conventional metal-based antifouling agents, and is working to bring out more such products. But he also emphasized that such R&D successes require lengthy laboratory and trial programs. R&D works “well in advance of actually putting a product on the market,” he said. Complicating such efforts is the daunting task of obtaining regulatory clearance of new technologies from multiple national regulatory authorities around the world, he added.

    Offering something of a dissenting opinion about the outlook for significant technical breakthroughs that could offer alternatives to metal-based antifouling agents was one panel-discussion participant, Alex Kaznoff of the U.S. Navy. Kaznoff, widely regarded as an expert on marine-coatings technology, said Navy researchers “have found some promising technologies” in the field. He said he was not at liberty to discuss technical details, other than to say these technologies originated with pharmaceutical manufacturers and are in “an early stage of evaluation.”

Potential Restrictions on Biocides Reviewed

The marine coatings conference also featured reports from major suppliers of copper-based coatings additives, who touted the effectiveness of their products and emphasized that copper has not been found to pose a hazard to marine life.

Neal Blossom of American Chemet Corp. discussed the work of a group called the European Union Copper Task Force, composed of representatives of suppliers of copper-based antifouling materials. The group includes American Chemet and several European companies and was created to promote and defend the use of copper agents in marine paints.

Blossom said the impending ban on tin-based compounds is causing a closer look at other biocides, a situation that is reflected in the European Union’s dictate that all biocide products be subject to a re-registration process that will result in a review of those products. An EU verdict on copper-based products is anticipated between 2006 and 2008 and at this point, suppliers are confident use of their products will survive the scrutiny, he said.

At the same time, however, the European Commission is pondering a move to define copper as being “persistent and bioaccumulative” in the environment. “Yes, it is persistent,” Blossom said, noting its widespread presence in nature, even in areas where the human role as a source is not considered to be a factor. But evidence appears to indicate that marine organisms do not physically retain, or “accumulate,” copper, he said.

In a discussion of “Copper Toxicity: Reality Versus the Myth,” Skip Klatt of American Chemet said the key challenge facing the marine-coatings industry is the development of superior antifouling performance in long-lasting coatings, with a minimum impact on non-target organisms. Other priorities are the optimization of biocide “leach life,” full depletion of the biocide during the coating film’s life, and compatibility of copper-based agents with new polymeric materials and co-biocides.

The conference chairman was John Tanner of Ameron International’s Performance Coatings & Finishes Group, who also is chairman of the NPCA’s Marine Coatings Committee. Assisting in arranging the technical program was William Allanach of International Paint Inc.