We tried to prepare composite particles that have carbon-black-dispersed polystyrene core and magnetite-powder-coated surface. In the experiment, the size and amount of magnetite powder added were mainly changed. As a result, the intended composite particles was prepared by suspension polymerization. With smaller size of magnetite powder, the size distribution of composite particles became narrower and the mean size became smaller. It was thought that the adhesion layer of magnetite powder was formed by the hydrophilic-hydrophobic interaction between magnetite powder and styrene droplets. The adhesion layer of magnetite powder was packed closely and formed multilayer.
Pyridine-triphenylborane (PTPB) is one of the alternative tin-free antifoulants in marine antifouling paints and has been used widely in commercial copper-free self-polishing antifouling paints in Japan. Analytical method for determination of PTPB at low parts per billion (ppb) level in seawater has been developed by high-performance liquid chromatography (HPLC) with UV detection at 220 nm after pre-concentration with C18 solid-phase extraction (SPE). PTPB leached from an antifouling paint film was extracted from artificial seawater using a C18 solidphase extraction (SPE) cartridge, and eluted with acetonitrile/pyridine (99 : 1). The recoveries of PTPB (25μg/l and 50μg/l) spiked into artificial seawater were 96% and 97%, respectively. The limit of determination of PTPB using 100ml of artificial seawater was 0.5μg/l for this analytical method. The HPLC-UV using SPE was applied onto measurement of the release rate (μg/cm2/day) of PTPB from copper-free antifouling paints containing PTPB according to both ISO 15181-1 and 15181-2.
Yellow pigments with safe characters, higher chroma with vivid yellowish color, higher tinting strength, and better durability are required especially in the field of color materials. In this paper, we prepared yellow composite particles, by coating titanium dioxide submicron particles with organic yellow pigment particles, assisted by methyltriethoxysilane as an adhesive agent. TEM photographs of the yellow composite particles indicated that the organic yellow pigment particles were adhered to the surface of titanium dioxide particles and formed the shell with uneven shape.The performances such as chroma, tinting strength and durability of the composite particles prepared by organic yellow pigment coating were improved to the same or above the level of conventional inorganic heavy metal pigment particles.