Eastman AQ 38S Polymer Can Increase the Efficiency of Sunscreens

Eastman Chemical Company announces today its Eastman AQ 38S polymer for sunscreen formulations. Recent tests demonstrate that water dispersible Eastman AQ 38S may lower formulation costs, reduce the amount of emulsifier needed, improve feel and sprayability, and increase the efficacy and water resistance of sunscreens.

Most water-based polymers must be neutralized using sodium hydroxide prior to or during formulation. This typically costly and time consuming trial-and-error process is avoidable using Eastman AQ 38S, which requires no neutralization.

“High performance Eastman AQ 38S is water dispersible right out of the box and offers superior water resistance and tactile quality in a lower cost formulation,” says Jim McCaulley, Ph.D., Eastman’s global market development manager, performance chemicals business organization. “This is just the latest example of Eastman’s creativity at work, joining our growing portfolio of innovative personal care ingredients."

Studies show that using Eastman AQ 38S is more efficient at lower concentrations than oil soluble polymers. Eastman conducted an efficiency study on the Eastman AQ 38S versus a typical oil-soluble polymer for SPF retention using the in vivo, standardized four 20-minute water-immersion test. Researchers used a 1 percent Eastman AQ 38S formulation versus twice the quantity of a competitive oil-soluble polymer formulation and found Eastman AQ 38S performed equally well despite the lower concentration amount. Both showed about 90 percent retention after testing. This significant difference can reduce cost, and can also lead to even better water resistance if the amount of AQ polymer in the formula is increased. Eastman AQ 38S enters the water phase and functions as an emulsifier for organic materials such as UV absorbers. Clustered AQ polymer chains move organic materials from the organic phase into the water phase, allowing for higher concentrations of additional materials such as UV filters for high SPF formulas. The AQ polymer also results in a more stable formula and allows formulators to reduce the amount of emulsifying agents, lowering the total formulation cost.

Combined with Eastman AQ 38S’s low viscosity sunscreens with this formulation also demonstrate an improved feel. The sunscreen’s superior spreadability not only enhances the consumer experience, but also helps to more evenly distribute moisturizers and UV inhibitors across the skin’s surface. Additionally, the polymer's inherent low dispersion viscosity also makes it ideal for sprayable aqueous formulations.

Eastman conducted various tests to determine the Eastman AQ 38S polymer’s water resistance. Eastman AQ 38S was added to a sunscreen formulation and compared against a leading-brand SPF 30 sunscreen claiming “very water resistant” performance –products with the best resistance to water. In an in vivo test, after four 20-minute immersions in water, the leading brand’s SPF reduced to approximately 28.5. Meanwhile, the Eastman AQ 38S formulation dropped to only to 29.5. In this in vivo test for SPF retention, researchers found that after four 20-minute dips the Eastman AQ 38S formulation retained 96 percent of its UV absorption, while the commercial lotion retained only 93 percent.

“It’s counter-intuitive that a water dispersible polymer could provide more water resistance than oil dispersible polymers,” says Edward McEntire, Ph.D., senior technical associate, Personal Care Laboratory at Eastman. “Our tests show that Eastman AQ 38S imparts performance, cost, and formulation benefits over currently used polymers.”

McEntire will present Eastman’s complete findings during a presentation at In-cosmetics in Paris on April 18 at 2:25 p.m. during the Cosmetic Science Conference.

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