Consumers around the world are increasingly demanding products which not only protect their skin against harmful UV radiation, but their hair too.

Whether they are going to the beach, sunbathing at the pool, or briefly at all outdoor activities, consumers are becoming more aware that they are putting their hair at risk – as a Datamonitor survey found (Bangkok 2014), in total, 29% of global consumers were concerned about sun damage to their hair.

With its Hair Care System UV Protection, BASF Care Creations offers a range of effective formulations which not only feature its proven broad spectrum UV filter, Uvinul® A Plus B, but which also ensure the filter adheres to the hair long enough to protect it. Consisting of a shampoo (Welcome Sun), an SPF conditioner (Beautiful Summer Hair), and a mousse (Enjoy the Sun at the Beach), the new system allows consumers to protect their hair against harmful UV rays and fading colour, while giving it a welcome treat.

There is convincing evidence that UV irradiation can lead to hair damage (e.g. Santos Nogueira et al., 2004; Lee WS, 2009). Whereas changes in hair colour are primarily attributable to UVA irradiation (320 nm–400 nm), UVB (290 nm–320 nm) leads to protein damage, and keratin damagein particular. This can leave the hair dry, brittle, and lustreless. The effect is sometimes referred to as photoageing of the hair.

To retain the hair shaft’s integrity, it is crucial to protect the hair cuticle – its outermost part. But how can we effectively protect our hair and scalps when the heavy lotions we use on our skin cannot be applied there? Consumers have indicated that they are interested in dynamic do-it-all products – such as shampoos, conditioners, and complementary products which contain UV filters. These products should help to protect the hair against the sun, while ‘moisturising’ it and reducing overall distress.

Hair care system UV protection

Specialists at BASF Care Creations have developed a range of hair care systems comprising various complementary rinse-off and leave-on hair care products. Harnessing their expertise in UV filters, they have now created a hair care system which leverages Uvinul® A Plus B, a widely tested and highly efficient broad-spectrum UV filter (INCI: Ethylhexyl Methoxycinnamate (and) Diethylamino Hydroxybenzoyl Hexyl Benzoate). Hair Care System UV Protection consists of a shampoo, a conditioner, and a mousse. Uvinul A Plus B (now referred to as ‘the broad-spectrum filter’) provides protection against UV-A and UV-B radiation, improves the stability of active ingredients and fragrances, and hinders their oxidation. The broad-spectrum filter is miscible in a wide range of cosmetic oils and solvents.

Figure 1. Test formulation HB-DE-13-2543

Proof of concept

Testing efficacy on human hair

In order to assess the efficacy of the broadspectrum filter as a UV filter on strands of human hair, various leave-on test frames were created. Three per cent broadspectrum filter was added to HB-DE-13254-3, 3% broad-spectrum filter and 1% vitamin E (Tocopherol Care) to HB-DE-13254-5, and 2% Uvinul MC 80, which is probably the most frequently used UVB filter worldwide, to HB-DE-13-254-7 (Fig 1). Vitamin E is a well-known antioxidant and plays an important role in helping to reduce skin damage caused by UV-induced free radicals: 1% was added to HB-DE-13-254-4, with no UV filter. HB-DE-13-254-6 was a placebo, containing neither a UV filter nor vitamins. HB-DE-13-254 contained Luviset® One because it allows the easy incorporation of different ingredients into a styling gel creme. Virgin Caucasian hair was used to test the UV protection capacity of the formulations.

Figure.2 Measuring UV penetration in the hair with ICL-H ©PCM

The efficacy of the test frame was measured in vitrousing induced chemiluminescence of human hair (ICL-H). ICL-H was performed by Institut Dr. Schrader Creachem GmbH and Differential Scanning Calorimetry (DSC) as a BASF internal measurement.

Induced chemiluminescence of human hair (ICL-H)

Induced chemiluminescence (i.e. the emission of light as the result of a chemical reaction) of human hair (ICL-H) is a highly sensitive in vitromethod used to measure the quantity of UV-induced photon emission.

The hair tresses were pre-washed with SLES solution and dried. A defined amount of the test formulation was applied. All measurements were performed under constant climatic conditions. The results were compared to the chemiluminescence of untreated hair strands. UV penetration in strands treated with 3% broad-spectrum filter was 22% lower than in untreated hair, and 23% lower than in strands treated with 3% broad-spectrum filter and 1%Tocopherol Care. By contrast, UV penetration in strands treated with 2% Uvinul MC 80 was 6% lower – and 12% higher in strands treated with the placebo.

Leave-on gel formulations containing the broad-spectrum filter clearly led to a significant decrease in UV penetration in the hair. Adding 1% Tocopherol to 3% broad-spectrum filter, however, did not significantly reduce UV damage further.

Differential Scanning Calorimetry (DSC)

The effect of the formulations was also measured using Differential Scanning Calorimetry (DSC) – the most sensitive method for quantitative determination of internal hair damage.

Again, hair tresses were pre-washed with SLES solution and dried. A defined amount of the test formulation was applied and left overnight. Afterwards the tresses were irradiated in an Atlas Xeneotest Alpha T for 72 hours (300 nm-400 nm, 150 W/m²). Prior to the DSC investigation, the strands were rinsed and dried overnight.

Figure.3 Keratin denaturation temperatures T/C after treatment with variou formulations, measured using DSC ©PCM

Figure.4 Keratin denaturation temperatures T/C measured using DSC ©PCM

Measured using DSC, the proteins of the virgin hair that was not exposed to UV irradiation denaturised at a temperature of 140.4°C. After 72 hours of exposure, they denaturised at 131.2°C. Hair strands treated with the placebo denaturised at 133°C, and when treated with the formulation containing vitamin E, their keratin denaturised at roughly the same temperature (132.9°C). A significant and reproducible UV-protecting effect was observed for the test formulation containing the broad-spectrum filter, which led to a denaturation temperature of 135.5°C – a difference of 4.3°C compared to untreated hair. The addition of vitamin E showed no effect here either. Therefore, the results of the DSC assessment confirmed the results of the ICL-H assessment – proving that the broad-spectrum filter provides significant UV protection for the hair.

DSC assessment of Hair Care System UV Protection

The efficacy of Hair Care System UV Protection was also assessed using DSC. Strands of Caucasian hair were treated with deionised water. The test strands were treated either with the shampoo and conditioner or with the shampoo, conditioner, and mousse. The shampoo contained 0.1% broad-spectrum filter, the conditioner 2.5%, and the mousse 0.2%. The strands were exposed to UV irradiation at 150 W/m2 for 72 hours at 42°C and a relative humidity of 42%.

Measured using DSC, the proteins of the hair strands treated with deionised water denaturised at a temperature of 129.9°C. The strands treated with the shampoo and the conditioner denaturised at 130.7°C, and those treated with both the rinse-off products and the leave-on mousse denaturised at 131.1°C.

Welcome, sun!

Comprising a shampoo (Welcome Sun), an SPF conditioner (Beautiful Summer Hair), and a mousse (Enjoy the Sun at the Beach), BASF’s Hair Care System UV Protection is a concept focusing on UV protection.

Welcome Sun’s key ingredients are the broad-spectrum UV filter and the multifaceted conditioning agent Plantasil® 4V – for better combability, even at higher levels of hair damage. In addition to the broadspectrum filter, the SPF conditioner Beautiful Summer Hair features: Cosmedia® TripleC, a cationic, liquid, high-performance dispersion polymer that enhances sensory and conditioning properties while improving viscosity; the lipid layer enhancer Lamesoft® PO 65, an essential ingredient in preventing the skin from drying out; and D-Panthenol 75 W, a pro-vitamin of D-Panthotenic acid (vitamin B5). Beautiful Summer Hair reduces scalp and hair dryness. With the broad-spectrum filter, the leave-on product Enjoy the Sun at the Beach completes the UV protection system. The styling polymer Luviquat® Supreme AT 1 provides unique effects such as ultra-strong hold and outstanding curl retention, even at high humidity levels, and lends fine, fragile hair more volume. In addition, the high-performance wax dispersion Lamesoft TM Benz conditions both hair and skin.

Conclusion

BASF’s Hair Care System UV Protection offers manufacturers a clear concept for integrating a highly effective broadspectrum UV filter in their products: Uvinul A Plus B has been tested in many ways and has now proven its efficacy when it comes to providing UV protection for hair. For both rinse-off and leave-on hair care products, adhesion of UV filters to the hair is crucial. With its Hair Care System UV Protection, BASF Care Creations has created a range of effective formulations which not only integrate a highly effective UV filter, but also ensure this filter adheres to the hair to protect it. The treatment with the shampoo and the conditioner raised the denaturation temperature of the hair proteins significantly, by 0.8°C. Strands treated with both the rinse-off products and the leave-on mousse showed a denaturation temperature 1.2°C higher than untreated strands. In conclusion, Uvinul A Plus B provides an effective means of UV protection for the hair, supporting UV protection claims.