MECHANICAL STABILITY OF ALKYD EMULSIONS .1. INFLUENCE OF EMULSION DROPLET SIZE AND THE EMULSIFIER

The limited colloidal stability of alkyd emulsions compared to that of organic solvent-borne alkyd paints is a well-known problem. For environmental reasons, however, the alkyd emulsions have a great advantage since they are waterborne. In this study, the influence of emulsifier and initial droplet size on the mechanical stability of alkyd emulsions was investigated. Anionic emulsifiers have been shown previously to be more effective than nonionic emulsifiers in the formation of alkyd emulsions. This study showed that an anionic emulsifier also gave more stable emulsions at lower concentrations than did the nonionics. If the concentration was increased, emulsions stabilized with a nonionic emulsifier showed the same stability as the one with the anionic emulsifiers. However, too high a concentration of surfactants is undesirable in paints, since it increases the water sensitivity of the paint film. The mechanical stability of emulsions stabilized with anionic emulsions was less sensitive to the initial droplet size than emulsions stabilized with a nonionic emulsifier.