Effect of surfactants used for binder synthesis on the properties of latex paints

Surfactants are commonly used during emulsion polymerization to produce stable dispersions of polymer particles for applications such as paints, adhesives and other coating applications. Surfactants can improve properties such as shelf-life, freeze–thaw stability and mechanical stability. However, the addition of surfactants can also have a negative effect on end-use properties, such as the water resistance of the coating. The type and amount of surfactant used is an important determinant of system behaviour during polymerization, film formation, and throughout the lifetime of the formed coating. The molecular architecture of binder particles is of crucial importance to latex paint properties. The type of surfactant used to stabilize binder particles had an effect on the adhesion of the paint to both alkyd-coated and Zincalume TM panels. The binders containing the polymeric surfactant showed better adhesion to these substrates, as they were better able to wet the surface of the substrates. However, polymeric surfactants also gave a greater amount of blistering when exposed to water and longer recovery times after exposure. The more hydrophobic the stabilization system, the greater the abrasion resistance observed, presumably due to the reduced extent of film plasticization by water. Accelerated weathering tests showed that these systems, designed to have low water sensitivity, gave good protection properties in regards to corrosion and blistering. UV exposure resulted in severe degradation of all films except where the binder contained acrylic acid, which is proposed to act as a photo-stabilizer.