Characterization of Ethyl Cellulose as W/O-Type Emulsifier and Application for Sunscreen

Abstract

The characterization of ethyl cellulose (EC) as a W/O-type emulsifier was studied. The results of emulsification with various oils found that EC was able to emulsify polar oils. The mechanism of emulsification was evaluated with the fluorescein labeled EC (FL-EC). As FL-EC exist on the interface of oil and water, and a continuous phase, it was suggested that (1) the stability of the emulsion was depended on the adsorption of EC on the interface and (2) EC can form a stable structure in the continuous phase. As the stability of the emulsion was inferior to that of emulsion using a surfactant, the improvement of the stability was studied. It was found that the stability of the emulsion was able to be improved by the addition of isostearic acid and sodium carboxy methyl cellulose. Since this base could emulsify of polar oils, the base could be useful one for sunscreen formulae. EC emulsified a UV absorbent and gave a high water resistance.