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A detailed mathematical model for a self-polishing antifouling paint has been developed. The important rate-influencing steps, dissolution of pigment particles, hydrolysis and erosion of the active polymer binder, effective diffusion in the leached layer, and external mass transport of relevant species, were all included. The aims have been to produce a tool for estimating paint lifetimes at various seawater conditions and paint compositions, for possible product optimizations, and for supporting the development of novel and environmentally friendly antifouling paints. Experimental data for model verification, such as polishing rates and extent of pigment leaching, were obtained using a laboratory rotor. Simulations performed for different rotary speeds and temperatures matched experimental data for two of the three paints investigated. In the last case, the disagreement between model and experiment was explained by significant water swelling of the hydrolyzed polymer. The modeling tools developed are applicable to other types of self-polishing antifouling paints than the ones investigated here.

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Rosin-Based Systems -[40 refs.]. -(YEBRA, D. M.; KIIL, S.; DAM-JOHANSEN, K.; WEINELL, C.; Prog. Org. Coat. 53 (2005) 4, 256-275; Dep. Chem. Chem. Eng., Tech. Univ. Den., DK-2800 Lyngby, Den.; Eng.) -Lindner 19-271

A cylindrical rotary ship simulator has been used to generate antifouling (AF) model paint performance data. First, computational fluid dynamics (CFD) simulations of the rotary setup and torque measurements demonstrate that the shear stress on the paint surface could be controlled to simulate real sailing conditions. Subsequently, polishing and copper leaching data for several commercially relevant tin-free, ablative, rosin-based AF model paints are presented. A high level of hydrophilicity and poor mechanical properties seem to characterize the base-case model binder upon exposure, partially due to the leaching of rosin derivatives and soluble plasticizers. Insoluble pigment particles (e.g., TiO 2 and Fe 2 O 3 ) and retardant resins are shown to significantly alter the polishing and leaching pattern of the paints. The use of scanning electron microscopy coupled with energydispersive X-ray detectors (SEM-EDX) to analyze exposed paint samples has provided detailed information about the polishing mechanisms of the paints tested. Namely, empirical evidence suggests a fast attainment of a maximum soluble binder conversion value, the magnitude of which is probably dependent on the amount of insoluble paint ingredients.