The working principle of wetting agent is mainly to wet the solid material by reducing the solid-liquid interfacial tension, so that water can spread on the surface of the solid material or penetrate into its surface. The working principle of wetting agent is to increase the viscosity and wettability of the surface of the material, reduce the air gap on the surface of the object, make the surface smoother, and increase the wettability of the surface of the material. Specifically, wetting agent can reduce the friction coefficient of the surface of the object, making the surface of the object easier to slide; at the same time, it can also prevent damage to the surface of the material, protect the surface of the object from damage, reduce the pollution and wear of the material, and thus extend the service life of the object.
The main components of wetting agent include two groups: hydrophilic group and lipophilic group. When the wetting agent contacts the solid surface, the lipophilic group adheres to the solid surface, and the hydrophilic group extends outward into the liquid, so that the liquid forms a continuous phase on the solid surface, thereby achieving wetting. Wetting agents can be classified according to the strength and nature of the action. According to the strength of the action, wetting agents can be divided into solvents and surfactants with low surface tension and can be mixed with water; according to the properties, wetting agents can be divided into anionic surfactants and nonionic surfactants.
In practical applications, the selection of wetting agents needs to consider their HLB value (hydrophile-lipophile balance) and the ability to reduce surface tension. The more the HLB value of the selected wetting agent matches the HLB value of the dispersed pigment and filler, the better the dispersion effect. For example, most inorganic pigments and fillers have a high HLB value (>13) and are hydrophilic pigments. Generally, no or less wetting agent is added, because adding wetting agent will increase the foam.