2003 ANNUAL SCIENTIFIC MEETING 219 OPTICAL CHARACTERISTICS OF TITANIUM OXIDE INTERFERENCE FILM AND THE FILM LAMINATED WITH OXIDES AND THEIR APPLICATIONS FOR COSMETICS Takahiro Kaida, Kota Kobayashi, Maoya Adachi and Fukuji Suzuki Nihon Koken Kogyo Company, LTD, 6-1-2 Ichiban-cho, Tachikawa-shi, Tokyo, Japan Introduction An infinite number of colors can be produced by mixing colored light. The colors required in color make-up must meet various demands, ranging not only from colorless to vivid new color tones, but also from ex1remely matte finishes to novel qualitative textures that shine in the light. Using current techniques, however, only colors and qualitative textures limited by the range of coloring materials whose use is permitted by safety considerations can be provided. Currently, color make-up products such as lipstick, eye shadow and the like show characteristics that are demanded by the combined use of organic pigments that show brilliant colors, or inorganic pigments such as iron oxide or the like. However, these make-up products are limited to color regions that are far removed from the color mixing of colored light. Furthem10re, in current coloring materials, various problems remain in terms of safety, light resistance, dispersibility, low coloring and the like. We have succeeded in developing, for the first time in the world, a method for synthesizing thin film form titanium dioxide whose optical thickness can be freely controlled. We discovered that this single-layer thin film form titanium dioxide emits color through interference phenomenon. Furthennore, by laminating various types of metal oxides as thin films, we developed a powder which shows coloring and brilliance that cannot be obtained in the case of conventional inorganic powders. We applied this developed interference color thin film form iron oxide coated titanium dioxide to color make-up, and discovered that new color tone variations and a different qualitative texture can be obtained. Materials and Methods Synthesis of Interference Color Thin Film Form Titanium Dioxide Titanyl sulfate (40 g) and ion exchange water (750 ml) were added to the 0.2 to 0.8 mm particle sized natural mica ( 15 g), and hydrated titanium oxide was deposited on the surfaces of the mica particles by heating and hydrolysis under agitation, and was then aged. This product showed a green interference color. Following rinsing with water, filtration and drying, the product was immersed in an alkaline aqueous solution (pH 12). The powder liberated in the supernatant was separated by decantation, and the titanium oxide layer was peeled from the surface of the substrate-form mica. In this way, a green interference color thin film form titanium dioxide was synthesized. Coating of Surface of Interference Color Thin Film Form Titanium Dioxide with Iron Oxide The interference color thin film form titanium dioxide was dispersed in ion exchange water then, an aqueous solution of ferric nitrate and an aqueous solution of caustic soda were added, and the surfaces of the interference color thin film form titanium dioxide particles were coated with iron oxide by a neutralization process. Powder Characteristics of Interference Color Thin Film Form Titanium Dioxide TI1e configuration of the powder was observed using a scanning electron microscope (SEM). The color tone of the powder was measured as follows: specifically, the powder was dispersed in a clear lacquer, and was applied to a black and white hiding-chart using an applicator. Then, tl1e color was measured at an incident angle of -45° and a light-receiving angle of -30° to 70° using a three­ dimensional variable-angle gloss meter. Results and Discussion Fig. 1 shows the results of SEM observation of the green interference color thin film form titanium dioxide. As is seen from this figure, the green interference color thin film form titanium dioxide is thinner plate-form powder than a conventional titanium dioxide coated mica pearl. Fig. 2 shows the color measurement results obtained using a three-dimensional variable-angle gloss meter. For purposes of comparison, color measurements were also performed for conventional titanium dioxide coated mica pearls (green interference mica pearl, blue interference mica pearl and violet interference mica pearl). As is seen from tl1is figure, tl1e green interference thin film form titanium dioxide showed a color variation from green to blue-green, blue and violet-blue according to differences in the light-receiving angle, and was an interference color thin film form titanium dioxide with a high flip-flop effect.

220 JOURNAL OF COSMETIC SCIENCE The surfaces of the thin film form titanium dioxide particles showing a green interference color were coated with iron oxide using fenic nitrate. Products with novel color tones and different qualitative textures were obtained by varying the amount of iron oxide applied as a coating and the calcination temperature. A high-brightness red colored powder with a deep and complex color balance and a vhid coloring based on the intelference effect was obtained. Furthermore, these titanium dioxide/iron oxide laminates showing such coloring had flip-flop properties, and showed variations in color and differences in appearance according to the viewing angle. These differences arise from differences in the thickness of the iron oxide coating and in the interference effect and absorption of light, and also from differences in the interference color according to the thickness of the tbin film fonn titanium dioxide. Thin film form titanium dioxide 44) lJII Common titanium dioxide coated mica pearl Figure I l l -80 IL- _,.:.. ---'-=--,---' ...f•• •••••••. -100 '---�-��- -68 -40 -10 Conclusion 10 ,40 60 Figure 2 80 100 Since tlie powder developed here has a coloring mechanism based on interference, unlike the coloring mechanism of conventional organic pigments and coloring materials based on the absorption of light, this powder is free from any concern regarding safety for the human body, and can solve various problems of color make-up. We consider that this powder is a superior cosmetic material which can exhibit a bright red color tone, which is a novel color tone especially for color make-up such as lipstick or the like, and a qualitative texture not seen in the past, e. g., a three-dimensional qualitative te:x"ture. References I. 2002 IFSCC Congress (EDINBURGH) Poster P219. 2. Japanese Patent Application Laid-Open No. 2003-55574