Hybrid Antifouling Paint Performance Study Of Fresh Water

Traditional biocidal antifouling coating is based on the mechanism of releasing biocides to seawater to prevent or kill animal and plant fouling organisms. Hyrbid type antifouling is the combination of rosin based (CDP type) and metal acrylic resin based (SPC type) coatings, which is aimed at a good balance of reasonable cost and optimal application properties. In the early time, coating manufacturers always concentrated how to develop paints with an excellent resistance to marine foulings and suitable cost. Recent years, however, as the duration of ship newbuilding has been prolonged, the longer outfitting time means tht the ships need to be immersed in freshwater for a longer time, it is a real challenge. Thereby expectations were placed on a good resistance to freshwater immersion issues.This thesis reported the collation investigation on major raw materials by use of control cariable method in swelling test. Physical assessment of hardness test and high pressure freshwater wash (HPFWW) test were carried out, and the experimental results showed that DINP (diisononyl phthalate) and the high sodium content CPT (copper pyrithione) in paint formulation majorly caused the swelling activity and obvious softening in freshwater, whcih probably rsulted in surface cracking and detachment from base coat. Meanwhile, using chloride paraffin as plasticizer and restricting the sodium level in the CPT did effectively reduce swelling rate and improved hardness in freshwater immersion. In addition, it was recognized that temperature of immersion water also did influence the water absorption and swelling behavior. When the temperature is high (35℃against25℃), the swelling rate became faster, this phenomenon can be reasonably explained by Penetration Theory. Three types of water (distilled water; tap water and Yangzi River water) were also compared and the three types of water had similar influence on softening, the possible reason is that they are all classified as freshwater.In summary, it showed that the swelling rate in freshwater have the same trend with the exact hardness in FW, our experimental results verified that the water absorption is the key reason of the film softening, which is a good reference for specifying borderline value of swelling test and the formulation screening test in freshwater in the future.