Polymers to Boost SPF, Water Resistance in Sunscreens

National Starch Personal Care presented a technical solution that is said to expand the use of inorganic UV filters in water resistant sunscreen formulations. The company researched sunscreen formulations manufactured with a special rheology modifier and a film forming polymer that, in combination, served to boost the water resistance properties of titanium dioxide and zinc oxide.

The research findings pave the way for makers of sunscreen products to incorporate inorganic UV filters into water resistant beach wear, sports wear and daily wear formulas without technical challenges. The company reported that adding its Amaze XT (INCI: Dehydroxanthan gum) polymer in conjunction with a water soluble film forming polymer to sun care products delivers enhanced SPF and water resistance to systems formulated with inorganic UV filters.

According to the company, it has been a challenge of formulators to make UV filters water resistant in sun care formulas. Sun care formulators give inorganic UV filters high marks when it comes to formulating products for broad spectrum protection, one of the most important attributes demanded by consumers today. Yet inorganic UV filters have been used in a limited set of sunscreen products because they are difficult to suspend in finished formulations without agglomeration. A lack of compatibility with rheology modifiers has further limited its use in sunscreen formulas.

In both in vitro and in vivo tests, water resistant sunscreens formulated with the aforementioned polymer combination remained stable and delivered water resistant protection. The company also found that adding its Amaze XT and its Dermacryl AQF polymers gave a higher in vivo SPF value in both pre and post immersion conditions.

The company believes its recent findings will be useful given the recent US Food and Drug Administration opinions. “Pending regulations regarding the measurement of UVA may prompt formulators to look closer at formulating with broad spectrum inorganic UV filter, and at strategies that effectively boost the SPF value of finished formulations made with these filters,” said Maria Tolchinsky, marketing manager at National Starch Personal Care, in a press statement.

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