Issue Date: May 8, 2006
Message In A Bottle
Terms such as "organic" and "natural" often get top billing on cosmetic labels. But the list of ingredients in small print on the back of the bottle tells consumers what manufacturers already know: Less glamorous synthetic polymers are often the real stars behind skin creams, hair sprays, sunscreens, and a host of other cosmetics.
To the average consumer, many of these ingredients are unpronounceable and even suspicious. However, polymers are workhorses offering many beneficial features. They make hair shiny and easier to comb, help to maintain moisture in the skin, protect skin from the damaging effects of the sun, enhance the visual appeal of a product, and generally make personal care products just feel good.
"One of the main advantages to working with synthetic polymers is the ability to tailor the molecule to give specific attributes," says Steven J. Semenczuk, personal care global business director for Lubrizol's Noveon business. Lubrizol acquired Noveon for about $1.8 billion in 2004 in part to expand into the personal care business. "You can adjust the chain length, amount and type of cross-linking, and the hydrophilic and hydrophobic nature of the molecule," Semenczuk explains.
These kinds of modifications can affect the flow characteristics−known as rheology−or emulsification capabilities of a polymer, he says. Equally important for the ultimate customer are sensory attributes. Chemists can design a synthetic polymer that influences the feel and flow of a product as well as its visual appeal on the shelf.
For instance, body washes in clear packaging are more attractive when a formulator can suspend materials such as hydrating capsules, exfoliants, and pearlescent pigments. Without some help, these visible additives might separate out of the product. But Noveon developed an alkali-swellable, lightly cross-linked acrylic-emulsion polymer, Carbopol Aqua SF-1, that keeps insoluble materials in suspension and, as a bonus, also increases stability for suspended materials such as silicones, Semenczuk says.
Noveon's latest development is Aqua CC. While the Carbopol line is traditionally anionic, Aqua CC is cationic, thanks to an amine component that has been designed in its structure. Semenczuk says this modification allows the polymer to thicken and stabilize in a lower pH range of shampoos and body washes than the anionic Carbopols can. It also allows the incorporation of cationic agents such as conditioning molecules.
When the personal care industry was looking for "natural feel" hair fixative ingredients a few years ago, Noveon came up with the Fixate line for gels and mousses. According to Semenczuk, the acrylate-based copolymers are designed with hydrophilic, semihydrophilic, and hydrophobic components that feel natural and don't flake, while keeping hair in place even in humid environments.
"Polymers are in vogue now for rheological control and also for texture, which consumers like," says Chris Holden, director of Cosmetic Rheologies, Manchester, England. CR, a specialist in acrylic-based rheology modifiers and conditioning agents, was acquired by Cognis in March for an undisclosed amount.
Richard Ridinger, group vice president of Cognis Care Chemicals, explains why Cognis, best known as a supplier of oleochemical-based surfactants and emollients to the personal care industry, has invested in a company with expertise in synthetic polymers. "Besides active ingredients, functional polymers will become one of the key drivers for innovation in hair and skin care," he says. "In fact, functional polymers are the preferred choice for satisfying the challenging demands for tomorrow's fashions."
Holden, who left Ciba Specialty Chemicals in 1999 to form CR with other former Ciba employees, says that as a small independent acrylic polymer maker, "we couldn't do what we wanted to do. We couldn't reach the big firms like Unilever and L'Oreal." But now, because of its association with Cognis, CR "has all the muscle and power of a leading raw materials company," he says.
About 18 months ago, the British firm launched a product it is betting will gain wide acceptance in both hair and skin formulations. According to Holden, Ultragel 300 "is made with everything we know about rheological modification." A cationic agent, the dimethylaminoethyl methacrylate polymer is designed to produce a transparent solution in water or water and alcohol blends. It also suspends nonionic and cationic ingredients. "We want to be the leading supplier of acrylic polymers across the industry," Holden says.
A polymer is also key to start-up Aquea Scientific's new product: an additive for soaps and shampoos that allows consumers to "wash on" a sunscreen. Martin Flacks, vice president of R&D for the Ventura, Calif., firm, says the proprietary production process involves encapsulating organic sunscreens such as octyl methoxycinnamate, octocrylene, and avobenzone in friable ceramic capsules. The capsules are combined with a polyquaternium polymer that leaves behind a positively charged film on the skin. Once on the skin, the capsules slowly dissolve in the film, evenly dispensing the sunscreen.
According to Flacks, a pharmacist by training and former vice president of product development and quality assurance for Unilever Cosmetics, the trouble with sunscreens, like drugs, is getting people to use them consistently. With Aquea's sunscreen system, consumers can wash, lather, and rinse, leaving behind active ingredients that will last six hours and provide Sun Protection Factor (SPF) ratings of between 2 and 20, depending on the formulation.
Aquea's backers include Kevin McGovern, a venture capitalist who also owns rights to patents governing use of α-hydroxy acids in skin care preparations, and David L. Compton, the former chief executive officer of a currency derivatives and commodities trading firm who now serves as Aquea's president. Flacks says the firm plans to apply its system to other ingredients including skin bronzers, bug repellants, and acne treatments.
Like Cognis, Degussa's Goldschmidt Chemical subsidiary is known for its naturally derived ingredients. "Everyone likes natural products, but they have their limitations," acknowledges Wolfgang Goertz, personal care marketing manager for the firm.
The quality of natural products may vary from year to year depending on the harvest. Plant extracts are often accompanied by unknown or unwanted material. On the other hand, synthetics are generally very pure and safe, Goertz notes. Chemists can modify synthetic molecules to develop what can't be found in nature, he says. This is especially true for silicone polymers, which often lend a velvety smooth feel to skin care products and provide a shiny appearance to hair.
Because of their hydrophobic nature, silicones tend to be used to formulate sunscreens that resist being washed off at the beach, notes Anna Howe, manager of applied research at Goldschmidt. Unlike traditional natural waxes, they feel light and silky on the skin, she adds.
To accommodate the trend toward sunscreen SPF formulations above 30, Goldschmidt sells a silicone-based emulsifier for high loading of both organic filters and mineral pigments such as titanium dioxide. Goldschmidt designed the emulsifier, known as Abil EM 90, with both polyether and alkyl side chains to help stabilize and disperse a sunscreen pigment system, Goertz says. Other formulations that require high pigment content, such as color cosmetics and liquid foundations, can benefit from the use of such a silicone emulsifier.
According to scientists at Wacker Chemie, silicones have made possible numerous contributions to cosmetic formulation since they became available more than 50 years ago. Among the latest advances are wax gels that are hybrids of waxlike alkyl components and silicones. In a marketing paper they wrote on the new hybrid silicones, Claudius Schwarzwälder, senior industry specialist, and Christina Ecker, laboratory assistant, say Belsil CDM 3526 VP and Belsil CM 7026 VP make it easier to comb wet and dry hair, enhance hair volume, and leave hair feeling softer.
Silicone waxes are already used in skin care and sun protection products and as structural components in lipsticks. But the new hybrids can be used in hair conditioners to trigger the release of active substances when heat is applied during blow-drying, Schwarzwälder and Ecker say.
Stephanie Postiaux, a Dow Corning cosmetic applications chemist, points out that silicones are highly versatile personal care product ingredients. For instance, the company's new 9701 elastomer is a silicone powder with a fused-silica-treated surface that prevents the powder from aggregating, Postiaux says. Incorporated in masking creams and compact foundations, the powder hides wrinkles and absorbs sebum, the oily secretions of the skin.
"You can do a number of tricks with polymers," Postiaux says. A new class of Dow Corning aerogel beads, which includes VM 2260 and VM 2270, is based on novel silica silylate technology. The beads have a high surface area and can thicken the oil phase of a cosmetic formulation; when incorporated into a skin cream, they absorb sebum on the surface of the skin.
Adding silicones to shampoos and conditioners makes hair shine, whereas a newer class of silicones helps dyed hair retain its color. According to Ulrich Sahre, technical service manager for the GE Bayer Silicone venture in Europe, Silsoft Q is a microemulsion for use in hair dye developers, shampoos, and rinse-off conditioners. Polyquaternium groups in the molecule grab onto and repair hair. And because Silsoft Q is a microemulsion, it easily penetrates the hair and prevents dye washout even after repeated shampooing, Sahre says.
Exposure to ultraviolet light from the sun can also affect hair color, be it natural or dyed, points out Alan E. Morrow, an area manager for Nalco. The firm, best known for its industrial water treatment business, has applied that expertise to personal care with a number of preservatives, as well as both conditioning and styling polymers. Two years ago, the firm developed Solamer GR8 to protect hair from both the UV-A-induced fading of artificial hair color and the UV-B-induced degradation and bleaching of natural hair color.
A proprietary polyamide, GR8 can be used in a number of leave-on and rinse-off hair care products. "It is a nice long-chain polymer that stays on the surface of hair," Morrow explains. Some large customers have approached the firm about qualifying GR8 as a skin care product. But he cautions that GR8 is not a Food & Drug Administration-approved sunscreen and that the firm makes no SPF claims for the product.
New Phase Technologies' family of highly branched α-olefins copolymerized with maleic anhydride make no SPF claims either, but they do enhance the SPF of approved sunscreen ingredients, the company says.
The principal use of the copolymer, known as Performa V, is to provide wash-off resistance without a greasy feel to sunscreen formulations, says Allison Hunter, applications research manager at New Phase, the personal care polymers division of hydrocarbon services firm Baker Petrolite. The maleic functionality of the copolymer helps it adhere to the skin, she says. And as a formulation containing the polymer dries on the skin, it forms a water-resistant film.
Other olefinic materials are finding uses in personal care. Honeywell, for instance, has relaunched a number of ethylene- and polyethylene-based materials under the new brand name Asensa. The name is intended to convey that the materials change the sensation of a personal care product, according to Philip Orawski, marketing manager. For instance, Asensa PR 200 is a low-molecular-weight polyethylene that looks like petroleum jelly, does not feel oily, and resists wash-off when formulated into sunscreens, he says.
Honeywell's micrometer-sized polyethylene waxes, such as CL 110 and CL 111, are used in silky feeling pressed powder cosmetics both to bind pigments and to ease the flow of the powder onto the skin. Honeywell is also exploring use of zeolites in personal care, where they are now mainly used for odor absorption, Orawski says. The firm currently makes zeolite molecular sieves that are used industrially as desiccants, adsorbents, and ion exchangers.
Very fine particles of nylon, about 5 ??m in diameter, are one secret to reducing the appearance of fine wrinkles, says Karine Loyen, technical manager at Arkema. The firm recently introduced Orgasol Soft Focus for powder sticks. Applied to "crow's feet" that appear at the corner of the eyes, the fine powder packs into wrinkles, diffusing light and making them seem to disappear, she says.
Other fine-particle nylon 6- or nylon 12-based materials from Arkema are used to absorb sebum and improve the texture of creams. Some variants are impregnated with organic sunscreens, which are slowly metered out on the skin, Loyen says. The firm is currently expanding its plant in Mont, France, to increase Orgasol production by 40%.
Despite their benefits, cosmetic ingredients based on nylon, polyethylene, silicone, acrylic, and other synthetic polymers are unlikely to get top billing on cosmetic labels. But whenever a label boasts "wrinkle-reducing," "waterproof," "color-saving," "soft," or even "natural-feeling," those attributes often come from the synthetic ingredients in the bottle.
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