ABSTRACT
The Role of Emulsifiers in General 414
Film Formation 415
O/W Sunscreen Formulations 422
Quick-Breaking O/W Sunscreen Emulsions 433
Sprayable O/W Emulsions 437
W/O Emulsions 440
Autoxidation of Emulsifiers 446
References 448
Although the formulation of emulsions is not all that easy, they are the most
frequently used vehicle for UV filters. Here, as in all emulsions, the most import-
ant structural element is the emulsifier system used; this system is primarily
responsible for the stability of the sunscreen emulsion. In addition to ensuring
emulsion stability across a broad temperature range, the emulsifier system used
contributes to many other quality characteristics of a sunscreen product, for
example, easy spreadability on the skin, the waterproofness of the formulation,
the film formation during and after application, the stability of the degree of
dispersion of micropigments, and product safety-to name only a few examples.