Kao develops a lipstick that vividly and beautifully colors even dull lips

 Kao focuses on the “original lip color” because there are many people who feel that the color is different from what they expected when they apply lipstick, and even those who have dullness on their lips can use vivid lipstick. We have developed the technology that can be obtained.

Focusing on the fact that there are various colors of lips, the company has divided them into four groups that have the characteristics of ``bright red'', ``no redness'', ``low saturation'', and ``dark''. I know from my research so far that it can be divided, and when I dig deeper into the research, since the lipstick coating is translucent, it is affected by the color of the lips. It has been found that dull lips with low lip color will also have a dull finish with lipstick.

In the research, we optically analyzed the difference in the finish when lipstick was applied to dull lips and dull lips, and found that dull lips lacked color development, especially in the red region. Based on this result, the company investigated a technology to improve red color development even on dull lips. As a result, it was found that it is effective to use a colorant having an optical property (scattering coefficient) that selectively increases scattering in the red region.

　In general, a red pigment that absorbs and scatters light to develop a red color is used, but the scattering coefficient in the red region decreases from the maximum value. In other words, since the scattering in the red region cannot be kept high, even if the red pigment is increased, it will appear "dark red" on dull lips.

Red interference pearl pigments are also well-known red pigments that develop a red color due to a phenomenon (interference of light) similar to how soap bubbles appear to have various colors, and their scattering coefficient remains high in the red region. Although it is maintained, it increases from the vicinity of the green region. In other words, it is not possible to increase only the scattering in the red region, and the color appears whitish red.

Therefore, when a red pigment and a red interference pearl pigment were combined, it was found that optical properties were obtained in which scattering in the vicinity of the green region was suppressed, scattering in the red region was maintained, and scattering in the red region selectively increased. . By applying such a red material to compensate for the lack of color development in the red region, it is thought that it is possible to create a coating film that has the same color development as when lipstick is applied to lips that are not dull even with dull lips.

Furthermore, when blended in lipstick, the inventors have found that the most effective color development is obtained by using a "red pigment-coated pearl pigment" in which a red pigment is adhered to the surface of a red interference pearl pigment. When lipstick containing this coloring material was applied, vivid color development was confirmed even on dull lips.