Innovative Solutions for Hair Color Maintenance
BASF researchers explain how two ingredients, ammonium cocoyl isethionate and polyquaternium-87, can help formulators create hair care products that keep color from fading.
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Technical Service Rep II
Hair coloring has become quite popular during the past several years, as consumers use color to ex- press themselves (regardless of whether they are making a dramatic change to enhance beauty), in- crease confidence or to simply cover gray hair in order to look younger and gain self satisfaction. According to Euromonitor, the North American hair colorant market last year was valued at approximately $2.3 billion with 2% growth forecasted between 2007-2012.1 It is not surprising that most manufacturers are actively developing products that are tailored for the hair color market. Since 2005 the Global New Product Database (GNPD) found 658 shampoos available with the word “color” and 243 products are available claiming “color protection.2
What’s driving the demand for color protection? It is the need for color maintenance. Today’s permanent hair colors are not truly permanent. Hair color products typically use oxidative dye molecules that are small enough to penetrate the hair and provide the instantaneous change the consumer desires. However, due to the small size of the dye molecule, they easily leach out of the hair, leading to fading or a change in tone upon exposure to physical, mechanical or chemical damage. Due to the cost of the service and the gratification achieved once a consumer subjects herself to hair coloring, it is desirable to minimize this change and loss of color. Furthermore, there is unavoidable damage to the cuticles associated to the process of hair coloring, which often leaves hair harder to manage and more difficult to comb. Hence the need for additional products that overcome the effects of coloring. Although it is impossible to prevent color loss, there are creative techniques that help minimize fading and improve hair maintenance.
Mild Sulfate-free Shampoos
No single source causes hair color fading. However, shampoo use is a major cause. This dilemma is one of the reasons why manufacturers are embracing the use of sulfate-free surfactants. Sulfate-free shampoos allow the use of hair cleansers while minimizing color loss. It is commercially accepted that the use of sulfate-free surfactants are generally milder compared to the often effective and efficient sulfate-based surfactants. Sulfate-free surfactants, considered to be less “stripping” than traditional sodium lauryl ether sulfate (SLES) surfactants, improve hair color retention.
BASF offers the ammonium and sodium cocoyl isethionate surfactants (Jordapon) for shampoo and body wash. These anionic surfactants are mild to the skin and eyes, impart a soft and creamy after feel and are excellent foaming agents in soft and hard water. In addition, they are vegetable-based and readily biodegradable in 28 days. The ammonium cocoyl isethionate grade (Jordapon ACI 30G), supplied as a 30% solution in water, has excellent water solubility, serves as a primary surfactant and is ideal for clear shampoo formulations. The sodium cocoyl isethionate (Jordapon CI) grades, which are popularly used in syndet bars, could serve as secondary surfactants when combined with ammonium cocoyl isethionate or other water soluble surfactants for opaque and elegant looking shampoos.
In addition to skin mildness, cocoyl isethionates are more forgiving to color treated hair. Comparisons of ammonium cocoyl isethionate (Jordapon ACI 30G) to SLES as revealed by Hunter Lab (UltraScanXE Model USXE) showed that ammonium cocoyl isethionate provides better color retention. Figure 1 below shows that a double bleached hair and albino piedmont hair colored with a red dye (L‘Oréal Technique Excellence HiColor HiLights Red), gave a lower positive delta E after a few number of washes with 0.5gm of a shampoo containing ammonium cocoyl isethionate and cocamidopropyl betaine (each hair was shampooed for one minute and rinsed for one minute). Meanwhile, the color treated hair washed by a shampoo containing SLES and cocamidopropyl betaine following the same procedure, showed a much higher increase in positive delta E. In this evaluation, the lower average positive delta E yielded a noticeable darker color than the higher delta E. These results suggest that the smaller the average delta E, the lesser the change in color fading therefore better color retention.
One of the drawbacks of some sulfate free surfactants is the inability to provide sufficient foaming. Consumers often associate foaming with cleansing of the hair. What differentiates these isethionates from other sulfate-free surfactants is their ability to deliver high and stable foam in hard water. Table I below shows that cocoyl isethionates are excellent foamers even in hard water. In addition, Jordapon ACI produces a dense, rich and small bubbled foam for a more elegant and premium looking shampoo.
One of the advantages of isethionates is their ability to build viscosity using salt as the thickening agent. A combination of 8% solids ammonium cocoyl isethionate with 5 % solids cocamidopropyl betaine yielded a viscosity of 15,000 cps (Brookfield DV-II + Pro Viscometer at spindle RV6 at 10rpm), and combination of 8% solids SLES with 5% cocamidopropyl betaine yielded a viscosity of 17,000 cps. The salt present in the betaine is sufficient to build viscosity in these shampoos. Further addition of salt could help increase the viscosity if a thicker shampoo base is desired.
Another highly recommended sulfate free surfactant is sodium C12-15 pareth-15 sulfonate (Avanel S 150 CG).
Used as a secondary surfactant, sodium C12-15 pareth-15 sulfonate is a special surfactant because of its hydrolytic stability at extreme pH levels. It should be the surfactant of choice when developing facial toners and antiseptics that require the use of alpha hydroxy acids. Furthermore, Avanel S150 has the ability to reduce skin irritation potential of known irritating surfactants, such as sodium lauryl sulfate as illustrated in Fig. 2.
Continuous coloring could lead to rough, unmanageable, difficult to comb and damaged hair. This uncomfortable experience is easily resolved by using effective conditioning systems that help overcome the damaging effects of hair coloring. Some very highly cationic polymers help improve the overall appearance of hair even at very low concentrations. Since hair is mostly negatively charged, high molecular weight polyquaternium compounds have strong affinity to the hair surface improving the combing and feel of the hair, leaving it healthy, smooth and manageable.
A new highly conditioning agent, polyquaternium–87 (Luviquat Sensa- tion) for rinse-off surfactant formulations such as shampoos and body wash, has been developed by BASF to help rejuvenate damaged hair. This highly charged polyquaternium offers excellent combability, superior volume control and leaves the hair soft and natural.
One of the toughest challenges a formulator faces is finding an effective conditioning system. It is well documented that the combination of silicone and cationic polymer in surfactants is one of the most effective conditioning combinations. Unfortunately, such a combination may have been covered by one of the patents in this field, thereby limiting a formulator’s ability to achieve the best wet combing reduction without obtaining a license from the patent holder.
Polyquaternium-87 offers the formulator the option to have an effective conditioning shampoo without the use of additional ingredient. It gives extremely high wet combing force reduction and could offer comparative benefits most effective silicone and cationic polymer combinations provide in shampoos (Fig. 3).
At 0.5% active solids, Polyquaternium-87 yielded over 80% wet combing force reduction while competitive conditioning polymers, PQ-10 and guar needed the addition of dimethiconol to achieve high wet combing force reduction.
Luviquat Sensation gives a creamy and sleek feel during rinse-off and provides a non-tacky, soft and natural dry feel. This highly cationic polymer helps rejuvenate damaged hair by forming an extremely thin patch network, approximately 10 to 20nm, on the damaged surface as revealed by atomic force microscopy. The resulting patch that is formed is light weight, very thin and helps preserve volume while improving combability and manageability (Fig. 4).
To evaluate the efficacy of highly cationic Luviquat Sensation on hair, we used the standard Rubine Dye test.3 In principle, the anionic Rubin dye (direct red 80) complexes with the cationic material deposited on the hair. To easily see the dye uptake, we used piedmont white hairs supplied by International Hair Importers. In this test, the white piedmont hair was soaked for 5 minutes in 0.2% solution of polymer in water. The hair was rinsed with tap water and inspected visually. The darker the pink or red color transferred onto the hair suggested that the samples have higher amount of cationic sites available, therefore providing more conditioning (Fig. 5).
Highly charged polyquaternium-87 had more cationic sites to which the Rubin dye could adhere. The cationic activity of polyquaternium-87 at pH 7 is 3.7meq/g while polyquaternium 10 and guar hydroxypropyltrimonium chloride both have approximately 1.0 meg/g. This suggests that the use of the highly cationic Luviquat Sensation provides a sufficient amount of conditioning agents to help rejuvenate the hair. Similar tests were done in a rinse-off shampoo using 0.2% active material in 10% SLES and 5% cocamidopropyl betaine. Results showed a more visible dye transfer using Luviquat Sensation compared to PQ10 and guar.
Polyquaternium-87 is supplied as a 26% solution of active material in water for ease of use. Due to its high compatibility with surfactants and physical property, polyquaternium-87 can easily be incorporated in most personal care products.
Protection from UV Rays
UVA and UVB radiation damage hair keratin and hair color by inducing the formation of free radicals. These highly reactive species result in color fading and off-tone color changes. Although UV radiation is not the only driver of hair discoloration, it is a strong contributor and for this reason it is appropriate to protect hair from free radicals generated by excess photo exposure. There are a number of references available that suggest that it is necessary to protect the hair from photo exposure from both UVA and UVB rays. Eric Abrutyn published and presented an evaluation of series of UV absorbers, concluding the need for protection from both UVA and UVB rays.4 Dr. Vittoria Signori wrote in her review that hair does not only require protection from the UVA and UVB spectrum but from VIS exposure as well.5 Dr. Zoe Draelos mentioned the need for intrinsic hair protection due to bleaching and ultimately damage to the fiber itself that are caused by sunlight. She added that the loss of pigment from root to tip and amino acid changes seem to predispose the hair shaft to more accelerated photoaging.6
BASF supplies many organic and inorganic broad-spectrum UV filters that are suitable for personal care applications. The organic UV filter, ethylhexyl methoxycinnamate (and) diethylamino hydroxybenzoyl hexyl benzoate (Uvinul A plus B), has excellent photostability and is miscible in a wide range of oils and solvents. Uvinul A plus B could be use in hair sprays, gels, mousses and shampoos, etc. The inorganic UV filter zinc oxide (Z-Cote Max) and titanium dioxide (T-lite Max) are carbopol compatible, broad-spectrum UV absorbers that can be use for waxes, pomades, styling creams and lotions.
Color retention is complex; there isn’t a single solution. A regimen or package of solutions is necessary to minimize color loss. The key is dealing with the many factors that cause accelerated color loss. The collective use of mild shampoos, efficient conditioning systems and sufficient UV absorbers could help consumers enjoy their hair color for a longer period of time.
The authors would like to thank Natalie Parish, Betty Aucar and James Carroll, all of BASF Corp.
More info: www.cosmetics.basf.com
2. GNPD database
3. US Patent No. 7048770, Azizova, Tasker and Oben, 2006.
4. E. Abrutyn; J. Soc. Cosmetic Chemist, vol.59, 365-367, 2008
5. V. Signori; J. Soc. Cosmetic Chemist, vol.55, 95-113, 2004
6. Z. Draelos; Dermatologic Clinics, 24(1), 81, 2006