Abstract
The structure and formation mechanism of secondary droplets in O/W emulsions and the contribution of their formation to the properties of cosmetic emulsions were investigated.
It was found that the secondary droplets were the aggregates of the emulsion droplets surrounded by liquid crystal of closed lamella type composed of surfactant, fatty alcohol, and water. In order to form secondary droplet emulsion, presence of an appropriate amount of fatty alcohol and optimum HLB range were necessary. The formation mechanism of secondary droplets was attributed to the existence states of fatty alcohol during the emulsification. The physicochemical properties of the emulsion chaged greatly with the formation of secondary droplets; a yeild value was shown in the emulsion and its stability was improved. secondary droplet emulsions possessed water-retaining ability and they showed skin moisturizing effect when they were applied to the skin.
All of these results are generated by the fact that the liquid crystal was formed in the continuous phase of the emulsion, thus fixing the emulsion droplets as well as water.
Cosmetic creams and lotions having excellent stability and skin moisturizing effect can be formulated by the application of those emulsions in which secondary droplets are formed.
