SURFACTANTS
Innovating surfactants beyond sulphate-free
Alex Palmer – Libra Speciality Chemicals
There has been a significant rise in ‘sulphate- free’ cosmetics in the personal care industry over recent decades. Certain surfactants like sulphates (or sulfates) have developed negative associations, with a ‘sulphate-free’ product tag implying a milder, and more natural product.1 The discourse on this topic is extensive, with opinions varying from marketing/consumer misconception to valid scientific evidence. Regardless of this shift, Sodium Lauryl
Sulphates (SLS)/Sodium Lauryl Ether Sulphates (SLES) remain the primary surfactant in the industry. The backwards focus of alternative products is potentially stalling the industry, which should look to innovate and improve, as opposed to relying on the ‘sulphate-free’ tag.
Surfactants in cosmetics Surface-active ingredients (surfactants) are used in cosmetics to reduce surface tension between water and dirt, hence allowing for the removal of dirt. Traditionally, cleaning surfactants are anionic and have five key responsibilities in cosmetics - cleaning, foaming, rheology control, skin mildness and polymer deposition.2
Surfactants
in products like shampoo and body wash need to be mild to avoid any skin irritation, they need to foam and lather whilst having wetting and detergent properties. Cosmetic cleaning products are formulated with one primary surfactant and secondary surfactants to enhance certain properties. The quantity and combination vary with product type, price, purpose and more. SLS/SLES have been the industry-wide primary surfactants, derived from coconut oil, palm kernel oil, or petroleum oil (see Table 1 for an example formulation of standard
SLS Formula
Ingredients Material option Base
Water Detergent
Secondary Surfactants
Viscosity Builder Boosters Primary
Sodium Lauryl Sulphate
Sarcosinate, Glucoside
Sodium Chloride, Alkanolamides Amine oxide
Sillicone, Glycerin Betaine, % Balance 20-35 3-8 2-3 0.5-2.5 Detergent
Secondary Surfactants
Viscosity Builder Boosters Primary
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SLS shampoo). Sulphates possess strong cleaning and detergency properties, being the best option and value available.1 Co-surfactants include sodium chloride
(salt), cocamidopropyl betaine (CAB) or alkyl polyglucosides (APGs). This also includes adding preservatives, fragrances and polymers, which are synthetic viscosity modifiers or conditioners. These additions to SLS/SLES formulations are relatively inexpensive while further boosting their properties, especially with cheap and readily available products like salt. These surfactants are good value and proficient cleaners, with properties that substitutes have struggled to replicate at the same cost and efficiency.3
CAB-LS Formula
Ingredients Material option Base
Water
Low Salt Betaine (CAB-LS)
Sodium Lauryl Sarcosinate
Sodium Chloride (<0.5)
Alkanolamides
Pearilser, Glycerin, Preservatives
% Balance 10-20 5-10 1-3 1-5
Table 1: Comparison of contents of two shampoo formulations, one based on standard SLS and the other on a low-salt betaine example (CAB-LS)
www.personalcaremagazine.com
Moving away from sulphates As mentioned, the discourse on sulphates is extensive and has been covered widely, with common belief of the chemicals being harsh and unnatural. This is caused by both the development of chemical research and the growing phenomenon of ‘chemicals = unnatural’ in media.4
These chemicals are associated
with skin irritation, toxicity and other negative cosmetic features. Consumer decisions and perception are sensitive to eye or skin irritation features, as well as drying of skin or hair. There are certainly milder and more moisturising alternatives to using sulphates, but the extent of this and other claims are unclear.1 Health concerns have strong connections
to bans and public health news that create this negative image. For example, 1,4-Dioxane has been classified as a potential human carcinogen by the International Agency for Cancer.5 1,4-Dioxane can be present by up to 300ppm
in SLES, added to reduce the chemical’s harshness. This byproduct is difficult to remove through
cleaning/ treatment and so is avoided.6 1,4-Dioxane has also been banned in products in states like California and New York (unless in minute traces).7
the reputation and future of sulphate-based surfactants. Claims on these surfactants are debated
constantly, titles like ‘corrosive’ or ‘toxic’ have been exaggerated and potentially
May 2023 PERSONAL CARE This has undoubtedly damaged
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