Objective:

In response to regulatory actions under consideration at both the national and international levels, the Naval Sea Systems Command (NAVSEA) has a long-term goal to reduce or eliminate the use of cuprous oxide as a biocide in antifouling (AF) hull coatings. The focus for alternative materials has been on biocide-free, low surface energy, silicone, fouling-release coatings that minimize the adhesion strength of the fouling organism to the coating and on copper-free, organic-biocide-containing coating systems. The main drawback to fouling release coatings is their mechanical weakness and the fact that they do not always adequately self-clean, and the copper-free systems have only been effective for relatively short periods of time (i.e., less than one year) in warm-water harbors. Neither coating system is the ideal solution.

Technology Description:

Microencapsulation of biocides offers the potential for improved, environmentally friendly, extended AF coating performance and greater formulation versatility. The process of encapsulation involves the deposition of a polymeric wall material around a central core or active agent. Adjusting parameters, such as wall material, wall thickness, crosslinking, capsule diameter, core loading, and concentration of microcapsules in the paint, can affect the eventual rate of biocide release. Initial research demonstrated that the formulation of microencapsulated, organic-booster biocides into ablative or self-polishing coatings systems resulted in a controlled release rate, extended performance life, and improved antifouling performance. This project will optimize, scale up, and demonstrate the long-term field performance of microcapsule-coating systems.

Expected Benefits:

The benefits of microencapsulation of biocides include (1) control of the rate of biocide release, resulting in highly predictable, steady-state rates of release; (2) assurance that more biocide remains in the coating over a longer period of time, resulting in extended utility and more effective performance; and (3) reduction in the rate of release of cuprous oxide. (Anticipated Project Completion - 2006)

Contact:

Mrs. Elizabeth Haslbeck
Naval Surface Warfare Center, Carderock Division
Building 60, Room 334, Code 641
9500 MacArthur Boulevard
West Bethesda, MD 20817-5700
Telephone: (301) 227-4784
Fax: (301) 227-4814
E-mail: haslbeckeg@nswccd.navy.mil