What is the effect of pigment dispersion on the coating?

In the use of paints, people often encounter problems such as flocculation, insufficient color or transparency, rheology or poor stability, all of which are closely related to the fact that the pigments are not sufficiently dispersed.

Purely speaking, "dispersively good" means that each pigment particle in the system is completely de-frozed, that is, each pigment particle is wrapped by a thin layer of paint or solvent. However, this is actually difficult to achieve. So, what effect does pigment dispersibility have on coating performance?

1. Gloss: If the pigment is dispersed, this can directly increase the gloss. In principle, the gloss is determined by the properties of the paint base. The addition of the necessary pigments only has an adverse effect on the gloss: if the pigment is not dispersed, certain pigment agglomerates will adversely affect the surface flatness and thus reduce the gloss due to diffuse scattering of light.

2, tolerance: weather resistance and chemical resistance will also be mainly determined by the choice of paint base. Insufficient dispersion of the pigment particles here also reduces the resistance. Pigment particles protruding from the surface provide a point of attack for chemicals and climatic factors. Conversely, if the correctly selected pigment is dispersed, the coating system resistance can only be improved, for example, by reflecting (TiO2) or absorbing ultraviolet radiation (iron oxide red) to improve weatherability. Proper pigment or extender pigments can also improve the chemical resistance of the paint base if dispersed.

3. Storage period: The storage period of the coating system depends largely on the quality of the pigment dispersion. When an excessive ratio of coarse pigment particles is present in the system, the adverse effects of precipitation of the coarse pigment particles are readily understood. Such stability problems are caused either by the so-called "post-wetting" of the pigment or by the re-flocculation of the opposite pigment. Post-wetting can be imparted if the pigment does not completely re-flocate just before the dispersion begins to completely disperse. The reason for the re-flocculation of the previously properly dispersed pigment dispersion is that the stability of the pigment slurry is good enough. This depends to a large extent on the stability of the paint base or the ratio of the binder to the solvent during the dispersion process. Solvents generally have excellent wetting properties, while binders are advantageous for stability. The problem is that the wetting (=solvent) and stability (=lacquer base) are the ideal combination.

4. Color, color strength, transparency and hiding power: All of these properties depend to a large extent on the surface of the pigment used, ie "dispersion". Complete dispersion of the pigment in the case of opaque pigments results in increased hiding power, greater color strength of the color paste (no flocculation), and better transparency in the case of clear pigments. For all pigments, complete dispersion of the pigment can result in a full presentation of the hue and "color purity" of the color.