Emulsification of Alkyds for Industrial Coatings

By Gunilla Östberg, Björn Bergenståhl

To date, alkyd emulsions have mostly been used in consumer paints. These are relatively easy to emulsify due to their low viscosity. Lately, alkyd emulsions for industrial paints have gained increasing attention. Alkyds for industrial paints have a much higher viscosity than alkyds for consumer paints which require other emulsification techniques.

In this work an alkyd with 40% oil length has been emulsified by the inversion technique. Inversion emulsification accomplished by adding water to an alkyd/surfactant mixture at constant temperature affords emulsions with droplet sizes below 1µm at a concentration of three percent on the alkyd phase. Small droplets are necessary for colloidal stability of the emulsion.

The solubility of surfactant in the alkyd and the water phase determines at which water concentration the emulsion inverts. High molecular weight ethoxylated anionic surfactants are effective as emulsifiers. Using these surfactants, the emulsification becomes less dependent on emulsification temperature than when nonionic surfactants are used.