FORMULATING FOR MILDNESS 105
Developing mild body cleansing products
Syed H. Abbas and Muzammil Amir - Seville Products LLC, Dubai
The current article covers the basic requirements for the development of mild personal cleansing products, formulation directions and brief of the methodologies to measure mildness and moisturisation properties of the products in the skin.
Effect of surfactants on product mildness Surfactants are the most important components of cleansing products. Their main function in the products is to give required quality and quantity of foam during the washing process and help in removing dirt and oily substances from the skin. Use of surfactants in fertilisers, medicines, foods and skin care products is based on their solubilisation and emulsification properties. Surfactant application in a lot of products is mainly due to the unique behaviour of surfactant molecules with hydrophilic and hydrophobic components present on the same molecule (Fig 1).
The two opposing parts of the molecules help in the formation of different types of aggregates in aqueous and non- aqueous medium which help in a vast range of applications of these surfactants in numerous product ranges. These aggregates can be in the form of micelles, liquid crystalline and solid phases. The repulsive forces between the hydrophobic group and water lead to the formation of a monolayer of the surfactants on the surface, and in the case of a mixture of water and oil, they form an interfacial layer which leads to the formation of emulsion dispersing the oil in water phase. In aqueous mediums these surfactants
form different types of liquid phases. At low concentration they form isotropic solutions while at higher concentrations different types of liquid crystalline phases are formed. These phases have different optical and rheological properties leading to a vast range of applications in various types of products. The formation of these different phases depends on the type of surfactants, minor ingredients in the products, type of solvents and the
April 2019 Abstract
With the increased health consciousness and change in lifestyles with time, it has become very important for companies associated with soap and cosmetic products to develop formulations which are safe and mild for their application on the body. The environmental conditions, global warming, and excessive use of chemical fertilisers all have forced consumers to be highly conscious of their health. Variations in weather conditions during the year have different requirements for product properties. Depending upon the location, the weather conditions are different in different countries which have an impact on the product attributes. Improved financial standards have created demand for mild products with attractive packaging and good aesthetics. Consumers are now slowly moving from economy to luxury products with an assumption that luxury products are better in quality and are suitable for health. These challenges have created a highly competitive market with a lot of effort from multinationals as well as small players to focus on Research and Development to create new and innovative technologies depending upon the consumer need. The substantiation of the claims needs extensive clinical and consumer test support.
Figure 1: Hydrophilic and hydrophobic parts of the molecule. Hydrophobic
temperature. Krafft point of the surfactant is another parameter which has to be understood by the formulator for the selection of surfactants for a particular application. Low Krafft Point in the range 0-5°C is needed for applications in liquid products while for solid products high Krafft Point above room temperature is required. In short the Krafft Point can be defined as the temperature at which the solubility of a surfactant increases very fast. In technical terms it is the temperature at which the solubility of the surfactant is equal to the Critical Micelle Concentration (CMC).The detailed description of the phases is beyond the scope of this chapter but it is important to know that these phases play a very important role in formulation development. Type of surfactants, their head group, hydrocarbon chain, aggregation number, size and the life cycle of the micelles are very important for understanding the mildness of the product.1
Hydrophilic
The cleansers in solid form require a high level of surfactants with high Krafft Point. Besides giving lather and having cleansing properties these surfactants provide structure to the products to keep it in proper shape. Surfactants in liquid products are mainly in the form of monomers, spherical micelles or rod micelles. Ultimately during use all the liquid and solid products pass through monomeric and spherical micelle forms during dilution with water. The unwanted oily components such as lipids, cholesterol and ceramides which are present on the surface of the skin get removed by getting dissolved in the core of the micelles along with the hydrophobic tails. Certain surfactant systems can dissolve the lipids and proteins from the barrier layer in the stratum corneum and create defects in these protective layers. This defect can have high epidermal water loss leading to drying, irritation and inflammation of the
PERSONAL CARE EUROPE
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