Viscosity stability of O/W emulsion containing α-gel through an ionic-complex system.
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.
Shiseido Research Center (Shin-Yokohama), Shiseido Co. Ltd., Kanagawa, Japan. makoto.uyama@to.shiseido.co.jp
Makoto
M
Uyama
Kaori
K
Ikuta
Takashi
T
Teshigawara
Kei
K
Watanabe
Reiji
R
Miyahara
D000438:Alcohols; D000838:Anions / Q000737:chemistry; D003358:Cosmetics; D004355:Drug Stability; D004573:Electrolytes; D004655:Emulsions / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D009821:Oils / Q000737:chemistry; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D013654:Taurine / Q000031:analogs & derivatives; D013997:Time Factors; D014783:Viscosity; D014867:Water / Q000737:chemistry; D038201:alpha-Crystallins
D000438:Alcohols; D000838:Anions; D003358:Cosmetics; D004573:Electrolytes; D004655:Emulsions; D005782:Gels; C580928:N-stearoyl-N-methyltaurine; D009821:Oils; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D038201:alpha-Crystallins; C514922:distearyldimethylammoniumchloride; D014867:Water; D013654:Taurine