wetting agent

Wetting and wetting agents

Wetting is usually a phenomenon in which a liquid substance has the ability to adhere to a solid and infiltrate, spread and penetrate the surface of a solid. The wettability is related to the surface tension of the solid and liquid, the smaller the surface tension of the liquid, the greater the surface tension of the solid, the better the wettability of the liquid to the solid, and the liquid can form a large distribution area on the solid surface.In the process of industrial production, many procedures are inseparable from wetting. Surfactants are the key to wetting, by adding such additives to reduce the surface tension of the liquid, and promote the liquid to better wet solid substances, this surfactant is the wetting agent.

According to the object of wetting, wetting agent is mainly divided into substrate wetting agent and pigment wetting dispersant, the former focuses on the wetting of the substrate and the coated surface, for the wetting of the cloth, the latter's role is to promote the wetting and dispersion of pigments and fillers in the substrate, for the impregnation wetting.

Substrate wetting agent

When coating the substrate with low surface energy, the substrate wetting agent needs to be added to the coating, which can not only improve the wetting and spreading property of the coating on the substrate, enhance the smoothness of the coating surface, but also prevent the undesirable phenomena such as shrinkage hole and shrinkage edge caused by the low surface tension of the substrate, and improve the adhesion of the coating film.

Dispersant for pigment wetting

The wetting of pigment particles is actually a surface displacement process, that is, the wetting agent molecules will remove the air displacement on the surface of the pigment filler, thereby reducing the interfacial tension between the liquid/solid, enhancing the liquid affinity of the pigment filler, in order to improve the dispersion efficiency and dispersion stability. In fact, the wetting, dispersion and stability of the pigment filler are three inseparable processes, and the prerequisite for the pigment particles to be fully dispersed and stable in the paint is to be well wetted by the liquid medium.

There are two key indicators for wetting agent selection: the HLB value of the wetting agent (the hydrophilic lipophilic balance value) and the ability of the wetting agent to reduce surface tension. The key to the selection of wetting agent is to select the auxiliaries that match the HLB value of the pigment. The better the HLB value of the selected wetting agent (hydrophilic and lipophilic balance value) matches the HLB value of the dispersed pigment and filler, the better the dispersion effect.

The role of wetting agent:

1.Can change the surface tension and permeability of the coating, can better wet the substrate, used to improve the adhesion of the coating.

2. It can assist in dispersing and assisting in dust prevention of fillers and pigments, and can assist in dispersing powder such as pigment fillers in the paint and assist in the subsequent anti-settling of anti-settling agent of the paint. In the anti-settling of the paint after opening, the anti-settling effect of wetting dispersant is far more important than that of anti-settling agent.