Wet dispersants can shorten the dispersion and grinding time of pigments and fillers during the coating production process, and keep the pigments and fillers in the coating in a stable dispersion state for a long time. They can even play a decisive role in certain properties of the coating.
Since both wetting agents and dispersants can reduce the surface tension of liquids, making it easier for pigments and fillers to disperse in the dispersion medium, people are accustomed to putting wetting agents and dispersants together as wetting and dispersing agents, but in fact The main functions and mechanisms of action of the two are different.
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Its own surface tension is very low and can significantly reduce the surface tension of the dispersion medium. The molecules of the wetting agent have a strong affinity with the surface of fine particles of pigments and fillers, and can be quickly adsorbed on the surface of fine particles, replacing the air adsorbed on the surface. , promote the wetting of pigments and filler particles by the medium and the deagglomeration of agglomerated particles in them.
In addition to having the same wetting effect as a wetting agent, one end of its active group can be adsorbed on the surface of pigments and fillers crushed into fine particles, and the other end is solvated into the base material to form an adsorption layer (the more adsorption groups, the more chain links) The longer, the thicker the adsorption layer), relying on charge repulsion (water-based paint) or entropy repulsion (solvent-based paint) to keep the pigment and filler particles in a dispersed and suspended state in the paint system for a long time.
When pigments and fillers deaggregate or are crushed into fine particles under the action of wetting agents and external forces, the dispersant compounds begin to selectively adsorb on their surfaces to stabilize the dispersed fine particles. Otherwise, without the stabilizing effect of the dispersant, the dispersed particles will reaggregate, flocculate and precipitate due to the effects of van der Waals attraction and gravity.