FORMULATING FOR MILDNESS
Mild cleansers with 'sulfate-free' surfactants
Peter Clark, Alice Miles, Jeannie Ang, Dr Steve O’Connor and Dr Russell Cox - Innospec Performance Chemicals
In the personal care industry, there is an ever-increasing demand for milder, naturally derived ingredients that has been driving the selection of raw materials globally. In addition, there remains a focus within the industry to find alternatives to sodium lauryl sulfate, and sodium lauryl ether sulfate. The reasons for the shift towards sulfate-
free mostly arises from reports of skin irritation due to exposure to both of these sulfate based surfactants.1
To facilitate the move to using
alternatives to alkyl sulfates and alkyl ether sulfates, Innospec have developed a wide range of chemistries based on both (alkyl) acyl amino acids and acyl (methyl) isethionate chemistries to improve skin mildness in formulations (Table 1). The drive towards sulfate-free started over
15 years ago when concerns were raised in an internet blog over the use of alkyl and alkyl ether sulfates in personal care products. Over the past ten years, consumer concern has continued to grow significantly causing market leaders to launch an ever-increasing number of sulfate-free formulations to both the consumer and professional personal care markets. One key thing to remember: economics will never be the driving factor in the journey to develop sulfate-free formulations. As previously alluded to, the number
of product launches claiming sulfate-free continues to increase. The following chart of data from Mintel demonstrates the growth of such products over the past ten years. The obvious anomalous year was 2020, for obvious reasons (Figure 1). The journey to developing sulfate-free
formulations is not an easy path to travel, and there are several technical and economic challenges to overcome: ■ Cost: We previously mention that sulfate- free surfactants, and therefore the formulations, are invariably more expensive compared to the sulfate-based products ■ Solid/Active Levels: Sulfate-free surfactants may require higher inclusion levels to achieve similar performance characteristics to a sulfate- based benchmark, e.g. foam volume ■ Thickening: Sulfate-free surfactants can demonstrate limited or difficult thickening character when using salt, and often require additional viscosity modifiers to achieve desired viscosities ■ Performance: Formulators and consumers need to understand and accept that there may be deficiencies when comparing sulfate
www.personalcaremagazine.com
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INCI
Sodium Lauroyl Methyl Isethionate
Sodium Cocoyl Isethionate
Sodium Methyl Cocoyl Taurate
Sodium Lauroyl Sarcosinate
Sodium Lauroyl Glycinate
Sodium Lauroyl Glutamate
Sodium Methyl Oleoyl Taurate
Sodium Lauryl Sulfate
Innospec Trade Names (Acronym)
Iselux® (SLMI)
Pureact I-Series (SCI)
Pureact WS Series (SMCT)
Pureact LSR (SLSar)
Pureact SCG (SLGLY)
O
Pureact GLT (SLGT)
Pureact MS-CG (SMOT)
Empicol® LZ, and LN (SLS)
HO NH O O 2 2 N O S O
Na +
4–10 O S O-Na+ O O
4–10 Low solubility
Table 1: Innospec has developed a wide range of chemistries based on both (alkyl) acyl amino acids and acyl (methyl) isethionate chemistries to improve skin mildness in formulations
November 2022 PERSONAL CARE O 2-7 O O O 2-7 N O O N 4 O O O-
N H
O O ONa
4.5–10.0 (Solubility decreases under acid pH)
Na+
6–11 (Low solubility below pH 6.0)
O- Na + O O- S Na +
Chemical Structure O O O O O- S Na+
Formulating pH Range
5-9 High solubility
O O- S Na+
6.0–8.5 Low solubility
4–10 High solubility
4-10 High solubility
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