Sweat enhances ultraviolet screening effect of sunscreen

Pola Chemical Industries Inc developed a sunscreen agent whose ultraviolet screening function improves when it touches sweat.

The new technology can be applied to emulsion-type sunscreen agents. Pola Chemical Industries, which is affiliated with the Pola Orbis group, developed the new sunscreen agent by using partially-hydrophobized silica powder of Nippon Aerosil Co Ltd (Shinjyuku-ku, Tokyo). Partially-hydrophobized silica powder is aggregated by ions contained in sweat.

Conventional sunscreen agents sometimes lose their ultraviolet screening effect due to the “re-emulsification” phenomenon, in which a surface active agent (contained in the coated layer) and sweat are well mixed and becomes flowable. As a result, when there is a large amount of sweat, they often cannot block ultraviolet light.

On the other hand, the new sunscreen agent does not use a surface active agent; therefore, it is not easily emulsified and is waterproof. Moreover, it can more efficiently cut ultraviolet light when the user sweats because ions contained in sweat aggregate powder and scatter ultraviolet light in the layer.

When the effect of the new agent was checked by using a plate designed for measurement, the powder was aggregated on the surface of the ultraviolet screening component after touching ions contained in sweat, increasing the thickness of the layer. Also, its ultraviolet screening performance increased by 14% after it touched sweat. Based on the results, Pola Chemical Industries concluded that the ultraviolet screening function of the agent is enhanced when it touches sweat.

Products using the new agent are scheduled to be released by Orbis Inc in the summer of 2017.

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