| 摘要 |
<p>The present inventors conducted investigations in order to develop a metal oxide which enables effective UV-screening; i.e. which has excellent screening ability against ultraviolet rays, particularly against long-wavelength ultraviolet rays, as well as excellent visible-light transmission; and to provide a UV-screening composition that contains the metal oxide and can be applied to external use. As a result, the present inventors have found that zinc oxide produced by a particular method has a characteristic form; i.e., primary particles having an average particle diameter of 50-100 nm aggregate in a planer shape, and a ratio represented by lnT360nm/lnT400nm (Txnm: transmittance of transmitted light of X nm) of 10 or more, and exerts excellent screening effect against long-wavelength ultraviolet rays as well as excellent visible-light transmission. The present invention has been accomplished based on this finding. The zinc oxide of the present invention effectively exerts the above-described excellent characteristics; i.e. UV-screening effect and transparency, and can be applied to a composition for external use such as make-up cosmetics or sunscreen cosmetics. <IMAGE></p> |
