86 SUN CARE n Control n 5% SunSpheresTM 30 25 20 15 12.5 10 5 0 Formulation A Figure 2: Screening formulations (In vivo results).
General procedures: l Mix all Phase A ingredients and heat the mixture to 75ºC
l Mix Phase B and heat mixture to 75ºC
l Add Phase B to Phase A l Cool to 40ºC and add Phase C (Soltex INO Polymer)
l Add Phase D (preservative) l Homogenise for 10 minutes
Hollow technology for solid sun care results Regardless of form, this SPF booster technology is enabled through a hollow sphere morphology that is prepared via controlled emulsion polymerisation. The polymer spheres take the appearance of dry, hollow beads, the centres of which can be seen in transmission electron micrographs of only the dried polymer. These air-filled hollow centres are key to the polymer’s mode of action and resulting performance enhancement in personal care applications.
In the context of sunscreen and other
UV-blocking cosmetics, the hollow spheres help raise the UV protection over the whole UVA/UVB spectrum, working equally well with organic and inorganic sunscreen actives. The polymer is also compatible with a broad range of cosmetic ingredients, including emollients and skin conditioners.
When form and function meet The ability to boost the efficacy of UVA/UVB filters enables formulators to use significantly less active to deliver the same level of SPF. As a result, potential irritation caused by the actives is reduced, and thus a more aesthetically pleasing product is delivered to end users. As Asian consumers seek comprehensive protection from the
PERSONAL CARE ASIA PACIFIC
sun and other environmental factors, the ability to provide rising SPF without compromising aesthetics and sensory feel is critical to remain competitive. Generally, the UV absorption capacity of
a formulation will increase in relation to rising concentrations of the SPF boosters. However, in some circumstances, an optimum level of concentration is observed, meaning that performance declines after a certain concentration is reached. Cases like these are why levels of the copolymer need to be screened to ensure that optimum performance is attained.
Putting the technology to the test To test its efficacy as an SPF booster in personal care applications, Dow scientists prepared two different sunscreen formulas and evaluated them in vivo and in vitro. Formulation A was relatively simple, containing low-oil and utilising an anionic emulsion system. The expected SPF of this formulation was rated at about 8. Sunscreen formulation B was a more complex formulation with a nonionic emulsifier and an expected SPF of approximately 15. Neither of these formulas was designed to optimise the performance of the SPF booster technology, and they were chosen based on their proven stability under the desired testing conditions. Both screening formulations (and their
controls) were tested for static SPF using the in vivo protocol specified in the Food and Drug Administration’s Final OTC Monograph (21 CFR Parts 310, 352, 700 and 740, May 21, 1999). Each sunscreen that contained the styrene/acrylates copolymer powder had a level of 5% solids. Physical stability was monitored weekly for three months.
Formulation B 7.8 +61% 14.9
+72% 25.8
actives
The formulation containing the SPF- boosting polymer spheres exhibited a significant boost in vitro, and retained the boost at both room temperature and 45°C for the length of the three-month evaluation. In addition, the experiment provided data showing that this technology significantly boosted the SPF of sunscreen formulations above their baseline performance, and did not interfere with or disrupt the formation or adherence of a water-resistant film. In fact, it is highly probable that systems designed to maximise the performance of Dow’s SPF- boosting polymer will obtain better results than those obtained in the company’s evaluations.
Further flexibility
The functionality of the SPF-boosting technology can be further improved by combining it with Dowsil™ ES-5300 Formulation Aid. This silicone emulsifier was designed to help formulators easily create low viscosity water-in-oil emulsions. With a low odour and light sensory, Dowsil ES-5300 provides stable cream and milky emulsions by low addition level and common mixers, optimal for sun care formulations.
For Asia Pacific formulators looking to strike an industry-leading balance between UV protection and seamless aesthetics, the SPF-booster technology should be considered in all its various forms and combinations as a useful tool in achieving that goal.
Conclusion
As distinct as it is vast, the Asia Pacific skin care market presents a unique opportunity for innovative sun care solutions to take hold. Billions of people are finding themselves amid an emerging middle class. They can afford higher quality, local products to meet their sun protection demands, which are far more stringent than most other markets. As the rest of the world becomes more
aware of the sun’s damaging effects, consumers across Asia remain resolutely ahead of the curve of this trend, hoping to completely block or even reverse the effects of UV rays. Formulators who can meet the high expectation of not only mitigating sun damage but eliminating it altogether will reap the benefits of this regional skin care boom. Suppliers with extensive track records of excellence — combined with future-focused, multifunctional portfolios of ingredients — can help make this heightened level of UV protection more than possible.
Reference 1 Yeomans M. Asia Leans Toward Premium Skin
Care. Happi. November 2019
PC
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