Posted in | Plastics and Polymers

Sunscreens with Bayer's Polyurethane Dispersion Can Boost Sun Protection Factor

Sunscreen sprays and lotions can benefit in a variety of ways when formulated with the polyurethane dispersion Baycusan C 1000 from Bayer MaterialScience. Although the film-forming polymer itself does not contain any UV-absorbing components, it can boost the sun protection factor (SPF).

In addition to having a pleasant skin feel, it also stabilizes emulsions - important particularly for sprays - and lends sun care products very good water resistance.

New, extensive tests underscore the versatile uses of this dispersion, which contains neither cosolvents nor preservatives. They confirm, for example, that the SPF-boosting effect is not restricted to formulations that include the UVB filters octocrylene and ethylhexyl triazone. Baycusan C 1000 also significantly increases the SPF of sample formulations with a protective effect based on UVA/B filters such as bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT) and benzophenone-3.

"Baycusan C 1000 is the perfect addition as SPF booster, particularly for formulations containing the modern, high-performance filter BEMT," says Dr. Sophie Viala, head of Technical Services for Cosmetic Raw Materials at Bayer MaterialScience. "Low-cost formulations can be produced with Baycusan C 1000 that feel very pleasant on the skin, meaning they aren't sticky, waxy or greasy."

Baycusan C 1000 also acts as a stabilizing raw material for oil-in-water (O/W) emulsions. Studies show that the polymer reduces particle size and distribution, thereby improving the stability of O/W emulsions. The cosmetic raw materials specialists at Bayer MaterialScience took advantage of this property to develop a sunscreen spray with a very low concentration of emulsifier. This low-viscosity formulation exhibits high water resistance, as confirmed by in vivo tests conducted in accordance with guidelines established by Colipa, the European Cosmetics Association. "With Baycusan C 1000, our customers are well-equipped to master the challenge of formulating sunscreen sprays with both high water resistance and high SPF," says Dr. Viala.

There are also new findings regarding the film-forming properties of Baycusan C 1000. The polyurethane dispersion was applied to synthetic skin. The resulting film withstood mechanical loads applied to the synthetic skin with virtually no microscopically visible damage, unlike the reference acrylate copolymer film, for instance. Films based on Baycusan C 1000 are very flexible, move with the skin and let it breathe, making sunscreens formulated with this dispersion very comfortable to wear.

Bayer MaterialScience will be presenting Baycusan C 1000 and other cosmetic products at the In-Cosmetics 2011 trade show, taking place from March 29 to 31, 2011, in Milan, Italy.

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