This new marketplace has brought several significant trends in Asian beauty and personal care. Female consumers are more interested than ever in skin whitening products and applications that help even skin tone. The region’s maturing population seeks help in delaying skin ageing and masking its inevitable effects. Meanwhile, consumer interest in natural materials prompts formulators to create skin care products that ensure pleasing aesthetics. On the hair care scene, greater use of colorants and heat appliances, along with the stress of everyday grooming, translate to the need for moisturisation, protection and repair. Specialty silicones have versatile and multifunctional roles to play in response to market trends. In fact, discerning global consumers have enjoyed the benefits of these materials for years, often not realising the range of silicone technologies that continue to shape product aesthetics and performance.
Why silicones?
Silicones are recognised by formulators and consumers alike for their sensory benefits and have been used in personal care products since the early 1950s. The term ‘silicone’ encompasses a vast array of technologies that can be combined among silicone families or with organic materials, including natural ingredients and actives. To improve the experience of consumers, formulators seek to optimise the texture and sensory characteristics of formulations to match their long-term functional benefits. With a light feel, ability to spread easily, lubricating qualities and tendency to repel water, silicones play a variety of roles in today’s personal care products. They can enhance the appearance of skin and hair, demonstrate durability and wash-off resistance due to their film barrier properties, improve sensory characteristics during and after application, provide innovative textures, protect and enhance hair strength, and deliver active ingredients with greater efficacy. Because silicones are multifunctional and often serve more than one use in a formulation, they can help make product development and manufacturing easier and more cost effective, since fewer ingredients may be needed. They are especially useful for formulating products that meet evolving beauty and personal care trends in Asia.
Silicones enhance skin whitening products
Various approaches for developing original skin whitening products depend on high-performance specialty silicones and technologies.
Caprylyl methicone
This non-occlusive alkylmethylsiloxane (Dow Corning FZ-3196) with moderate volatility can improve aesthetics in skin whitening formulations. It also responds to consumer interest in products based on natural ingredients, a formulation advantage for a wide range of skin care applications. Paired-comparison tests evaluated formulations containing whitening actives plus natural oil and butter alone or in combination with various silicones used for enhancing texture and aesthetics, such as silicone elastomers and silicone elastomer suspensions. Formulations with the specialty silicones showed a range of sensory effects that could also be adapted to other formulations. In general, the specialty silicones enhanced the aesthetics of the natural oils, providing better spreading and smoothness with less residue and tackiness. Figure 1 illustrates the impact of alkylmethylsiloxanes on the sensory profiles of gel creams combining natural oils and butters and whitening actives. The best combination was obtained with caprylyl methicone, resulting in reduced tackiness and improved smoothness. Caprylyl methicone can also be used as a carrier for other ingredients, or as a dispersing medium for hydrophobic powders and pigments, allowing a wider scope of whitening products that incorporate novel ingredients.
Phenyl trimethicone
This specialty silicone fluid (Dow Corning 556 Cosmetic Grade Fluid) offers good compatibility with a variety of silicones and organic ingredients used in skin care products. It also aids pigment dispersion for more even colour in cosmetics. In water-in-oil sun care products, addition of 4% phenyl trimethicone can boost the in vitro SPF and UVAF of formulations containing organic sunscreens. Similarly, 4% of the silicone in oil-in-water sun care formulations can boost in vitro SPF and UVAF in the presence of organic sun screens and titanium dioxide. Because it spreads easily with lubrication and glide, and also imparts smoothness without stickiness or greasiness, this silicone can be useful in lotions, creams and skin whitening products where easy application and comfortable wear are important to consumers.
Silicone elastomers
In skin care applications, silicone elastomers provide dry smoothness and a light, silky, non-greasy skin feel, while absorbing quickly. The INCI name for this type of polymer often contains the term crosspolymer (e.g., dimethicone crosspolymer). Dow Corning 9040 and 9045 Silicone Elastomer Blends, for example, can act as thickening agents for water-in-oil and water-in-silicone formulations and silicone fluids. Because of their sensory and functional properties for skin care applications, they may also be useful for formulating skin whitening products. Formulation 1 illustrates the use of a silicone elastomer blend and phenyl trimethicone in a liquid foundation based on a water-in-silicone emulsion. Liquid foundation is an important trend in Asia, especially China. However, it can be challenging to formulate a stable product while having a reasonable level of pigments to ensure good skin coverage. Silicone elastomers are also available in powder form (Dow Corning 9701 Cosmetic Powder) and can absorb high levels of oils, including sebum.1 Blends of silicone elastomer powder and other powders can enhance skin whitening products by providing optical effects that mask skin imperfections. Silicone elastomer powders also show their versatility as delivery agents for active ingredients such as organic sunscreens. The powder does not require predispersion, even in the presence of pigments, and its structure makes incorporation possible into a range of skin care and colour cosmetic formulations without using sophisticated processes or equipment. The silica-coated elastomer is appropriate for applications in creams, lotions, gels, face masks and products that exfoliate or offer sun care, whitening or anti-ageing benefits. Numerous potential applications exist in colour cosmetics, including pressed and loose foundation powders and makeup, eye shadow, blushers, liquid foundations, lipsticks and bronzers.
New solutions for anti-ageing products
Although whitening is the primary focus for Asian women, wrinkles also are an issue, making materials that help mask these signs of ageing a consumer need. The popularity of BB creams, originally developed in Korea, also has increased significantly in Asia. This new product form can play an important role in hiding skin imperfections. Silicone elastomers can help provide the feel and texture for BB creams as well as the needed coverage. They can be used to create innovative BB cream textures, with more liquidity than the traditional forms, yet still with very good coverage and a distinctive powdery feel, all in combination with whitening actives and sunscreens. The silicone elastomer powder coated with silica can be used to absorb sebum and mask wrinkles, while maintaining the unique sensory profile of silicone elastomers. In Figure 2, a silicone-in-water cream with the silicone elastomer showed improved aesthetics after absorption: decreased tackiness, greasiness, gloss; and significant improvement in slippery and powdery feel. In evaluations with 21 panellists, there was an improvement in the appearance of wrinkles for 75% of the subjects, with a significant total mean decrease of 28% (p<0.01).2 Because of its wrinkle-masking properties, this silica-coated elastomer is particularly appropriate, but not limited to, anti-ageing applications in combination with anti-ageing actives.
Hair care for an evolving market
Style-conscious consumers are driving the Asian hair care market with creativity and fashion diversity. The choices seem endless: geometric styles with bangs; soft, loose cuts with feminine fringe and wisps; cropped pixies; retro waves and curls – and even traditional straight, shoulder-length tresses. In addition to this there is vibrant colour. Bold highlights, even reds and blondes, join the darker, more natural shades. Whatever the style or colour, healthy-looking hair is a must, and conditioning is essential. Ultraviolet radiation, curling irons, and chemicals from colouring, perming and straightening – even frictional forces from daily combing and styling – all contribute to hair damage. In the case of coloured hair, regular washing can lead to discoloration. Although conditioning is critical for healthy hair, consumers increasingly look for products that also help prevent damage and maintain hair beauty. With their excellent spreading and substantive properties, silicones can deposit on the hair shaft to offer conditioning, protection or repair in several ways.
A new silicone emulsion for Asian hair
A new silicone emulsion developed for Asian hair responds to consumers’ interest in hair moisturising. But what exactly does ‘moisturisation’ mean? The answer points to primary aspects of conditioning – consumers perceive their hair to be moisturised when they can easily comb through dry hair that feels soft, smooth, and sleek. Dimethicone (and) amodimethicone (and) laureth-23 (and) polyquaternium-10 (and) laureth-4 (Dow Corning CE-1689 Smoothing Emulsion) is a nonionic emulsion based on high molecular weight polydimethylsiloxane (PDMS) and amodimethicone fluids. Designed for two-in-one shampoos and rinse-off conditioners, it improves dry combing as well as dry and wet sensory feel at use levels of 1% to 3%. An added benefit with the smoothing emulsion is easy formulating. In a typical formulation, it would be added below 45°C to the formulation, followed by simple mixing. Formulation 2 illustrates the use of the smoothing emulsion in a novel conditioning application. Colour protection is another benefit offered by the smoothing emulsion. In evaluations based on this material, results are expressed by E value. After 16 wash cycles and 64 hours of UV radiation, the shampoo containing 3% smoothing emulsion showed a significant difference in colour protection compared to a control shampoo without the silicone (Fig. 3). The lower E value for the shampoo with the smoothing emulsion indicates the silicone helps retain the colour after repeated washings. Hair shine can also be perceived as a component of hair moisturisation. Phenyl trimethicone, which could be useful in skin-whitening and anti-ageing products, is recognised as a useful silicone for imparting shine to hair from rinse-off conditioners.
Beyond conditioning
Another easy-to-use specialty silicone conditions hair and demonstrates protection from heat and improved permanent colour retention. The nonionic microemulsion, silicone quaternium-16 (and) undeceth-11 (and) butyloctanol (and) undeceth-5, (Dow Corning 5-7113 Silicone Quat Microemulsion), allows formulators to more easily incorporate the quaternary polymer into formulations. Because it is a microemulsion, it can be used to produce clear formulations. Formulating is easy, requiring simple pour-and-mix procedures. In addition, due to its small particle size, the microemulsion can be used without stabilisers. Heat protection is an important aspect of conditioning. The moisture content of hair is crucial to maintaining its healthy appearance and feel. Processes such as blow drying and curling with hot irons can rapidly reduce hair moisture content below its normal level and can lead to damage. Hair dryers and other heated appliances first soften the keratin of the hair. If the appliances are too hot, they can actually cause the water in the hair to boil, forming minute bubbles of steam inside the softened hair shaft, weakening the fibre and potentially leading to total fracture. Silicones conduct heat very slowly, so a silicone film along the hair shaft helps reduce moisture loss and resulting heat damage. Silicone also helps the hair cuticle lie flat, giving hair a smoother, softer and more healthy appearance. Analytical assessments using dynamic thermogravimetric analysis (TGA) were completed to establish the possible role of silicones in reducing the loss of water from hair fibres. Tresses were treated with various silicones and the treated hair was subjected to various heating cycles at a rate of 10°C per minute, ranging from 25°C to 300°C. Figure 4 compares the results of hair tresses treated with three silicones vs. no silicone. All the silicones helped retain moisture in hair over a broad temperature range, with the silicone quat microemulsion performing best. Consumers also show interest in products that help strengthen hair. With their inherent conditioning ability, silicones can address the physical and environmental causes of hair damage. They can be especially useful in products designed for weakened or damaged hair. The ability of silicones to impart a perception of moisturization and control frizzy hair certainly contributes to the overall conditioning effect. A silicone film can also enhance the strength of hair that has a tendency to frizz, or that is naturally finer and more prone to damage. In a recent study, single-fibre tensile testing was the chosen study method to test hair strength. It is both scientific and quantitative, and is a recognised measure of hair strength.3-7 In addition, results are not affected by friction resistance; silicones are already known for reducing friction. The single-fibre tensile tests demonstrated that two silicones in particular, the silicone quat microemulsion and an amino phenyl silicone resin (Dow Corning 2-2078 Fluid), can enhance hair strength, making hair less prone to damage and breakage. Figure 5 shows an example of how the samples treated with dilute leave-on solutions exhibited higher work of elongation compared to the untreated control. Studies by Dow Corning that show improved combing properties, enhanced shine, and added benefits such as colour protection or hair strengthening were conducted on hair without heat damage. In contrast, studies to evaluate hair repair focused primarily on heat-damaged hair. They demonstrate the use of silicones to renew smooth feel, improve hair glide, decrease dry feel and dry appearance, and aid combing, avoiding further damage by lubricating the fibres and reducing the number of broken fibres. Sensory studies help demonstrate the repair benefits of silicone. One series of evaluations compared dry sensory benefits from a leave-in conditioner for the silicone quat microemulsion, a control containing no silicone, and a commercial benchmark. For glide, results showed a 16% improvement over the control and a 31% improvement over the commercial benchmark. For smoothness there was an 18% improvement over the control. Results for glide and smoothness were significant at a 99% or greater confidence level. For friction reduction (i.e., decrease in hair dryness) the silicone-containing conditioner showed a 17% improvement over the control at a confidence level of 95%.
Conclusions
Specialty silicones are multifunctional materials that answer consumer demand for novel textures, distinctive aesethetics, and high performance. They also can make formulating easier and more cost effective. By fulfilling more than one function in a formulation, they may eliminate the need for additional ingredients. Moreover, silicones are among the most extensively studied and tested materials used in beauty care, giving consumers the safety and performance they look for in today’s highly competitive marketplace. Evaluations of the various functional properties of specialty silicones can help formulators rapidly screen these materials based on performance requirements or formulation chemistry. This approach can lead to faster development times and commercialisation for innovative skin and hair care products.
References
1. Vervier I, Courel B. Masking wrinkles and enhancing skin feel with silicone elastomer powder. Cosmet Toiletries 2006; 121 (11): 65-74. 2. Marchioretto S, van Doorn S. Silicone microemulsion expands formulating opportunities for hair care. Euro Cosmetics 2010; 18: 20-3. 3. Marchioretto S, van Doorn S. Silicones as protective agents in hair care products, presented at the 10th International Conference on Surfactant and Detergent (ICSD), Shanghai, China (September 2008). 4. Scharfeld T, D’Arrigo C, Lim KH. A single hair fibre tensile tester for operation under a scanning electron microscope. Massachusetts Institute of Technology, 1-5. 5. Syed AN, Ayoub H. Correlating porosity and tensile strength of chemically modified hair. Cosmet Toil 2002; 117 (11): 57-64. 6. Syed AN, Ayoub H, Kuhajda A. Recent advances in treating excessively curly hair, Cosmet Toil 1998; 113 (9): 47-56. 7. Johnson B, Quackenbush K, Swanton B. Silicones for hair strengthening. Cosmet Toil 2007; 122 (3): 59-64.