Five major influencing factors of defoamers in coating formulations

The five major influencing factors of defoamers in paint formulations:

Factor 1: Surface tension

The surface tension of defoamers must be lower than that of coatings, otherwise they cannot have defoaming and anti foaming effects. The surface tension of coatings is a variable factor, so when selecting defoamers, the surface tension should be kept constant, and the surface tension variation factor should be taken into account.

Factor 2: Influence of additives

Most surfactants used in coatings are functionally incompatible with defoamers. Especially emulsifiers, wetting dispersants, leveling agents, thickeners, etc. can have an impact on the effectiveness of defoamers. So when combining various additives, it is important to pay attention to the relationship between different additives and choose the optimal balance point.

Factor Three: Baking Temperature

When the coating is baked at high temperature at room temperature, its viscosity will decrease instantly at the beginning, and bubbles can move to the surface. However, due to the volatilization of solvent, the curing of coating, and the increase of surface viscosity, foam will become more stable and retain on the surface, resulting in shrinkage and pinholes. Therefore, the baking temperature, curing speed, and solvent volatilization rate also have an impact on the effect of defoamer.

Factor 4: Solid content, viscosity, and elasticity of the coating

High solid thick film, high viscosity and high elasticity coatings are very difficult to defoamer. In these coatings, defoamer diffusion is difficult, micro bubbles become larger slowly, foam migration ability decreases, foam viscoelasticity is large and many other adverse defoaming factors exist. It is best to use defoamer and defoamer together.

Factor 5: Coating method and construction temperature

The degree of foaming of different coatings varies depending on the coating method used. Brush coating and roller coating have more foam than spray coating and scraping coating. High temperature has more foam than low temperature, but high temperature can easily eliminate foam.