The viscosity stability of O/W emulsion containing [alpha]-gel through an ionic-complex system

• Published in: Journal of oleo science Vol. 62; no. 1; p. 9
• Main Authors: Uyama, Makoto, Ikuta, Kaori, Teshigawara, Takashi, Watanabe, Kei, Miyahara, Reiji
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Science and Technology Agency 01.01.2013
• ISSN: 1345-8957; 1347-3352

Although many active ingredients are used in cosmetic products for moisturizing and whitening the skin, they are often electrolytes, and the stabilities of oil in water (O/W) type emulsion formulae containing electrolytes are generally difficult to control. To solve this problem, formulae containing an α-crystalline phase (α-gel) consisting of water, higher alcohols, and anionic surfactants such as sodium N-stearoyl-N-methyl-taurate (SMT) have been developed. However, in spite of their excellent salt tolerance, these formulae have poor viscosity stability under non-electrolyte conditions, and the viscosity decreases over time. To obtain adequate viscosity stability, the required electrolyte concentration is approximately 1wt%, which is somewhat high for cosmetic applications. To replace the salts, distearyl dimethyl ammonium chloride (DSAC), a cationic surfactant, with an opposite electric charge to SMT, was used in O/W emulsion formulae, resulting in improved viscosity stability at a lower concentration than that of salts. The stabilization mechanism with DSAC was found to be different from that of salts.