Harald Frommelius

A new concept for dispersing agents in aqueous coatings

After a short overview about the development of synthetic dispersing agents for solvent-borne coatings up to the actual state of technique, analogous concepts of polymeric additives for water-borne coatings are introduced. The performance of these polyfunctional dispersants will be critically reviewed and described in comparison to dispersing agents based on new concepts. With these new concepts using mono- and difunctional oleochemical agents or a combination of them it is often possible to reach better performance than with polyfunctional polymers. During our study different physicochemical methods (Zeta potential, adsorption, desorption) and paint application tests including numerous binders and pigments were done. These investigations lead to the discussion of new models for the dispersing of pigments in water-borne coatings and to more knowledge about the design of a dispersant to reach high gloss, optimal rub-out and high color-strength. Furthermore the formulation of solvent- and resin-free water-borne pigment pastes is possible using dispersing agents selected by the new concepts.