PPG-15 Stearyl ether is the INCI name of a non-ionic surfactant. In terms of structure, it originates from the group of chemical compounds called propoxylated fatty alcohols. This means it is a product of reactions between higher fatty alcohols (mostly of petrochemical and oleochemical origin) and propylene oxide. The global CAS number for PPG-15 Stearyl is 25231-21-4.
In normal conditions, at atmospheric pressure and room temperature, PPG-15 Stearyl exists as a colourless or slightly yellowish liquid characterised by low viscosity and the consistency of oil. Its colour in the Hazen scale exceeds 25 units. It has no characteristic odour. Its freezing point is around 0oC, which makes it easy to operate with the ingredient during various processes. In chemical terms, PPG-15 Stearyl is an ether of propylene polyglycol and stearyl alcohol. It is an excellent emulsifier, solvent and carrier substance. It features a high boiling point of 423oC and an ignition point of around 160oC. The approximate molar mass of its molecule is 312 g/mol. It perfectly dissolves in oils, and its commonly used concentrations range from 1 to 10%. The pH level for a 10% solution is slightly acidic or slightly basic and ranges from 6.0 to 8.0. The hydroxyl value for PPG-15 Stearyl oscillates from 58 to 70 mgKOH/g. It is empirically proved that solutions of this substance contain the antioxidant BHT, i.e., 2,6-di-tert-butyl-4-methylphenol, also called butylated hydroxytoluene, in the amount of 0.05 to 0.1%. PPG-15 Stearyl is resistant to extreme environmental conditions. Its activity is stable, whether in a strongly acidic or basic environment, with a pH ranging from 2 to 10. It is an ingredient of plant origin, with high polarity, so it solves very well in similar, popular polar organic solvents. PPG-15 Stearyl is a non-ionic emolient, an occlusive substance which indirectly improves the softening, greasing and smoothing properties of formulations. It is excellent as a solubilizer, complementing water solutions with ingredients which are not dissolved in the formulation or are sparingly soluble, for example scent compositions or plant extracts. It also acts as a coupling agent, being an adhesion promoter which enhances the adhesion between materials and forms chemical and physical bonds that link the surfaces. Given its non-ionic nature, it can be a component of formulations based on non-ionic, anionic and cationic surface active agents, reducing the potential of strong, irritating surfactants. It shows strong wetting properties. It is compatible with all types of oils and waxes, whether natural or synthetic.
In cosmetics, the commonly used PPG-15 Stearyl acts as an emollient and a conditioning and softening substance. In cleaning agents and skin and hair care products, it removes dirt and moistruizes surfaces. It is also used as a coupling agent for mineral oil and esters in hydroalcoholic systems, acting as the base for aromatic compositions. It efficiently dissolves crystalline UV filters and improves the wettability and capillarity of pigments. This makes it suitable as an ingredient in body care cosmetics, sunscreens with SPF, colour cosmetics, creams and balsams. It ensures an excellent distribution of creams and balsams on the skin, lubricating it without leaving a fatty film. PPG-15 Stearyl is thus a cosmetic oil which does not cause the occlusion effect on the skin. It prevents the skin from drying and leaves it soft. When used in hair care cosmetics, it forms a protective film that prevents their overdrying, e.g. due to other solvents that are present. Given its solubilizing properties, it serves as a solvent for aromatic oils and active ingredients, as well as for dispersing oils and pigments. When applied in deodorants and antiperspirants, it reduces skin irritation caused by them and gives the feeling of relief. PPG-15 Stearyl can also be found as a lubricant in nail varnishes, tonics and aromatic spray emulsions.
