94 SUN CARE


Staying safe and carefree in the sun


n Dr. Brigitte Lindemann, Stephanie Acker, Stanislaw Krus, Ann Marie Vieira – BASF, Germany Abstract


Formulating high-SPF sunscreens represents a challenge for manufacturers: The large oil phase usually necessitated by UV filters that are oils or only soluble in oil tends to weigh down sunscreens, resulting in products that are inconvenient to apply and that leave an unpleasant feeling on the skin. BASF recently developed a new technology that incorporates the oil-soluble, high-performance, broad-spectrum UV filter Tinosorb®


S in the water phase. The UV filter formulation Tinosorb®


manufacturers of sun care products to develop sunscreens that combine maximum protection with a light sensation on the skin.


To protect their skin against the damaging effects of the sun, consumers want light, pleasant-feeling sunscreens: Products that are easy to apply and are quickly absorbed without leaving their skin feeling greasy, while also providing a high sun protection factor (SPF). But since most UV filters are either oils or oil-soluble, formulating products with a reduced oil phase can be challenging for manufacturers. BASF experts recently developed a new technology that incorporate the oil-soluble, high-performance and broad-spectrum UV filter Tinosorb®


S (INCI: Bis-


Ethylhexyloxyphenol Methoxyphenyl Triazine, abbreviation: BEMT) in the water phase by solubilising the filter active in a polymer matrix. Tinosorb S Lite Aqua (INCI:


1600 1400 1200 1000 800 600 400 200 0


290 300 310 320 330 340 350 Wavelength (nm) Figure 1: Absorbance spectra of UV filters in solution, red: effective broad-spectrum BEMT. PERSONAL CARE ASIA PACIFIC November 2019 360 370 380 390 400


Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine (BEMT) (and) Acrylates/C12-22 Alkyl Methacrylate Copolymer) enables manufacturers to include the same active in both the oil and water phase – facilitating light formulations with a reduced oil phase. In vivo and in vitro tests have proven the performance and water resistance of formulations with the solubilised BEMT. High-SPF formulations contain several


carefully balanced UV filters, most of which are oils or soluble in oil. The resulting high proportion of UV filters in the oil phase is at odds with consumer demand for light, pleasant, low-viscosity formulations. Moreover, oily formulations can lead to problems such as a greasy, unflattering residue and general discomfort. There are


only a few UV filters available for the water phase: Water-soluble or nano-particulate dispersions. These filters make it possible to incorporate UV protection in both the oil and water phases, for easy spreadability and an even distribution on the skin for maximum effectiveness.1


Incorporating BEMT in both water and oil phases Among the most effective oil-soluble filters is the broad-spectrum UV filter BEMT, marketed by BASF under the trade name Tinosorb S. BASF experts have developed a technology that brings BEMT into the water phase by solubilising the filter active in a polymer matrix.2


The cosmetic UV filter formulation sold under the trade name S Lite Aqua enables


E1%/1cm


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