A Novel Technique for Preventing Pigment Sedimentation in Nail Enamels

To prevent sedimentation of inorganic pigments used in nail enamels, we studied a surface treatment of the pigment, using a titanium dioxide. We selected a variety of fluorides to improve the electrostatic repulsion by the pigment's surface charge and adsorption of resins on the pigment surface. The result indicated that the pigments had excellent electrostatic repulsion as well as excellent resin adsorption. Our experiments with pigment dispersion containing these pigments confirmed that the particle diameter did not change with time and that pigment aggregation did not occur. Nail enamels formulated with these pigments offer extremely stable dispersion. Within this group, pigments surface treated with perfluoroalkyl phosphate were the most effective in preventing sedimentation and that a dispersion stability of 5 times or longer than the conventional life cycle could be obtained.