L’Oréal Patents Multilayer Particle Sunscreen

US Patent 12,029,801 B2 (Jun Sasai, Toshifumi Shiroya); L’Oréal, Paris, patented a multilayer UV filter particle comprised of an odd number of alternating layers of high and low refractive index materials.

Each layer has a refractive index that differs from that of adjacent layers by at least 0.2, the total number of layers is at least 9, and the particle does not contain a substrate. The high refractive index material has a refractive index of larger than 1.7 and less than 5.0. The low refractive index material has a refractive index of lower than 1.65. The high and low refractive index materials are metal oxides.

The thickness of each of the layers of the high refractive index material ranges from 3 to 100 nm and the thickness of each of the layers of the low refractive index material ranges from 10 to 150 nm.