Parametric Study of Tin-Free Antifouling Model Paint Behavior Using Rotary Experiments

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., TiO2 and Fe2O3) and retardant resins are shown to significantly alter the polishing and leaching pattern of the paints. The use of scanning electron microscopy coupled with energy-dispersive 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.