SKIN PROTECTION 99


Changes in sun care: UV protection and beyond


 Karolina Krupińska, Felix Wilson - Aston Chemicals, UK


Modern consumers lead busy lives and are becoming increasingly demanding of the products that they purchase. Although most consumers are aware that excessive sun exposure can be dangerous, everyday use of sunscreen products is often neglected. Manufacturers are therefore motivated to constantly improve sun care products to make them more aesthetically pleasing, as well as effective. High efficiency, multi-functionality, and easy application are crucial to the modern sun care product.


The importance of product aesthetics and correct application In general, sunscreen products are perceived as difficult to apply and likely to leave greasy, white marks on clothes and digital devices, which are factors leading to their improper use. Consumers usually apply insufficient amounts of sun protection products to the skin, and as a result, obtain 20-50% lower protection than desired.1


A


key challenge of formulators is therefore to improve the sensory properties and spreadability of the product. Consumers are also lax in subsequent reapplications, so it is important to extend the durability of the cream by increasing its resistance to water and other factors such as chlorine, temperature, sweat, and transfer.


Product form Emulsions The form of the product undoubtedly influences its sensory properties and ease of application onto the skin. Oil-in-water (O/W) emulsions are usually lighter and feel more pleasant, but water-in-oil (W/O) systems are characterised by greater water resistance, which is a significant advantage for sunscreen products. To counter the heavier feel of W/O systems, silicones are often used in the continuous phase of the emulsion as they provide a silky feel. They also improve the


April 2019


as more suitable for sensitive skin. Hydroxystearic acid is a structuring agent that can gel hydrocarbons, esters and even some silicones whilst retaining clarity, giving formulators an easy-to- use tool for making this product format.3


such as PEG-10


dimethicone/vinyl dimethicone crosspolymer also allows the use of water-soluble


components in a stick structure, greatly increasing the range of actives that can be included in otherwise anhydrous formulations.4 The stick format is also often used for soothing and cooling applications in after sun products. Menthol is often used for a cooling


even distribution of the cream on the surface of the skin, contributing to a higher SPF value. Thanks to a new emulsifying system based on a blend of polyglyceryl-4 isostearate, coco-caprylate/caprate, and disteardimonium hectorite, it is possible to obtain natural W/O emulsions with extremely light textures, similar to that of water-in-silicone emulsions.2


The emulsifier


achieves this by promoting the formation of large droplets in the internal aqueous phase, giving a lighter, fresher feel than traditional W/O emulsifiers.


Sticks


Emulsions are the most common form of sun care products, but less common formats include oils, two-phase mists, and most recently sticks. The recent trend for sticks came to Europe from South Korea where they are very popular because of their convenience and clean, ‘hands-free’ application.


A popular sub sector of sun sticks are


transparent sticks, which leave no colour residue upon application and are perceived


effect upon application. Menthol can be irritating to the skin so it is recommended to use it in the form of menthyl PCA in combination with octyldodecyl PCA, giving a milder cooling effect without skin irritation, while also stimulating the synthesis of epidermal lipids.5


Calamine is


another material that is often incorporated into after sun sticks for its skin calming properties.


Convenience, ease of use, and multi- functionality are becoming ever more important for consumers. For these reasons the range of available sunscreen products is constantly expanding and now also includes more controversial formats such as wet wipes, shower bars and sun care products with ‘wash on’ technology.6, 7


UV filters: Avoiding issues and obtaining ideal performance Formulating with UV filters is not easy and there are numerous factors to consider when using them. There are two main types of UV filters; organic filters, also known as ‘chemical’ filters, and inorganic or ‘physical’ filters. Recently, there has been a slight move away from the use of organic filters, which absorb UV radiation, as they can degrade and can cause allergic reactions. Inorganic filters such as nano titanium


PERSONAL CARE EUROPE Novel silicone elastomers


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