Development of Sunscreen Having Excellent Washability with Specific Inorganic UV Scattering Agents and Dispersants

Abstract

An increased awareness regarding the negative effects of ultraviolet (UV) rays on the skin has led to an increase in the use of sunscreen; two types of sunscreen—non-chemical and chemical—are present in the market. The non-chemical type has the characteristics of water resistance and safety but is difficult to remove via ordinary cleansing; thus, special cleansing agents are needed to remove sunscreen from the skin. On the other hand, the chemical type has the characteristics of washability and good texture although this type raises concern about skin irritation, depending on skin type. In this work, a sunscreen having sufficient water resistance and excellent washability was developed by optimizing the combination of inorganic UV scattering agents (IUVSAs) and inorganic UV scattering agent dispersants. First, we paid attention to the IUVSAs treated with an N-acyl amino acid having both hydrophobic and hydrophilic groups. In addition, we studied combinations of IUVSAs and the various dispersants. Finally, we developed a sunscreen having sufficient water resistance and excellent washability by using the IUVSAs treated with the N-acyl amino acid and specific dispersants.