Preparation of Oil-in-Water Emulsion with a Good Texture of Use and Waterproofness Using the Gemini Surfactant

Abstract

We investigated the development of an o/w emulsion with a good texture of use and waterproofness. We considered the Gemini-type surfactant, which can disperse oil using a small amount of emulsifier, to be suitable to achieve the objectives, and investigated using sodium dilauramidoglutamide lysine (International Nomenclature of Cosmetic Ingredients (INCI) name; a Geminitype compound obtained by treating sodium lauroyl glutamate with lysine). We report that the expected good results were obtained. The critical micelle concentration of sodium dilauramidoglutamide lysine was found to significantly decrease compared with a monomer (sodium lauroyl glutamate), and we evaluated the emulsifying capacity. As a result, sodium dilauramidoglutamide lysine, can emulsify various types of oil with a small amount (0.03 to 0.1%) regardless of the blended amount (10 to 50%), and the emulsion showed good stability (almost no change in the particle size between the baseline and after 1 month at 50℃). In a comparison of the waterproofness between the emulsion prepared with sodium dilauramidoglutamide lysine and that emulsified by a non-ionic surfactant using the cup-shaking method, the former contained more components in the oil phase in the skin or hair. In addition, it was less oily, could be spread more smoothly, and provided a fresh texture of use after application compared with a non-ionic surfactant since it was emulsified in a small amount.