Abstract
In this study, the stability of O/W cosmetic facial cream emulsions according to HLB values was evaluated by mixing nonionic surfactants, such as Brij 78&72 and Brij 98&92. Brij 78&72 (steareth-20&steareth-2, EMS-01), saturated fatty acid, and Brij 98&92 (oleth-20&oleth-2, EMS-02), unsaturated fatty acid, were used as mixed surfactants. The stability of the O/W emulsion was evaluated by using the emulsion viscosity, particle size, particle size distribution, and zeta-potential. The viscosity of the emulsion increased with the increase of time for EMS-01 while that of EMS-02 decreased with the increase of HLB value. The particle size of both EMS-01 and EMS-02 increased with time. The emulsifier with a HLB value of 10.8, which is the most similar to the required HLB value of mineral oil, 10.5, had the smallest particle size and highest density and also showed the highest emulsion stability. The zeta-potential of both emulsions tended to increase with the HLB value. No significant changes were observed in emulsions of the HLB value of 10.8 or more. The saturated fatty acid system, EMS-01, exhibited a higher zeta-potential value than that of the unsaturated fatty acid EMS-02 and also was superior in the stability.
본 연구에서는 비이온성 유화제인 Brij 78&72와 Brij 98&92 유화제를 혼합하여 HLB value에 따른 O/W 유화액의 안정성을 평가하였다. 혼합유화제로는 포화지방산인 Brij 78&72 (steareth-20&steareth-2, EMU-01)와 불포화지방산인 Brij 98&92 (oleth-20&oleth-2, EMU-02)를 사용하였다. 또한 O/W 유화액의 안정성은 유화액의 점도, 액적크기, 액적크기분포, zeta-potential 등을 이용하여 평가하였다. 시간에 따른 유화액의 점도는 EMU-01의 경우 증가하였고, EMU-02는 HLB value가 증가함에 따라 감소하였다. 액적크기는 시간에 따라 두 유화제 모두 증가하였으며, EMU-01과 EMU-02 모두 mineral oil의 required HLB value (10.5)과 가장 유사한 HLB = 10.8의 유화제가 액적크기가 가장 작고 높은 조밀도를 보여 유화 안정도가 가장 우수하였다. Zeta-potential은 두 유화액 모두 HLB value에 따라 증가하는 경향을 보였으며, HLB = 10.8 이상의 유화액에서는 큰 변화를 보이지 않았고 포화지방산계인 EMU-01이 불포화지방산계인 EMU-02보다 큰 zeta-potential을 나타내어 안정성 측면에서 우수하였다.