chapter  20
36 Pages

The Role of Surfactants in Sunscreen Formulations

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.