Surfactants are critical components of aqueous systems because they provide a wide range of performance attributes. In aqueous pigment dispersions such as paints or colorants, surfactants must facilitate the milling of pigment and provide adequate stabilization of the dispersed pigment, while at the same time ensure letdown compatibility and optimal application performance. Rarely is just one surfactant used in a pigment dispersion; more often, two or three surfactants are added in order to achieve specific performance and process attributes. A formulator must balance these requirements, managing the complex interactions between the system components to avoid the frustrating cycle of adding one surfactant to resolve one deficiency only to cause a new problem to tackle. This article will review the basic types of surfactants commonly found in an aqueous pigment dispersion and provide guidance on when and how each is best employed to minimize formulation development and troubleshooting.
Aqueous dispersion is the stabilization of insoluble solids in an aqueous medium using surface active agents. Classically this process is described in three steps:1