Eight major functions of dispersants in coatings

A surfactant that has two opposite properties: lipophilic and hydrophilic in the molecule. In water-based coatings, dispersants not only reduce viscosity during the formulation process, but also affect the final performance of the coating.

1. Prevent settlement

The principle of dispersant to prevent settlement is the same as above . Pigments with small specific surface area and large particle size are easy to settle. The dispersant prevents the pigment and filler particles from flocculating through charge action and steric hindrance, and controls their particle size within a certain range, which can prevent the pigment and filler particles from settling and is beneficial to the preservation of the paint.

2. Prevent flocculation

There are many reasons for the flocculation of pigment and filler particles. Generally, Pigments with large specific surface areas and small particle sizes are more likely to flocculate. On the one hand, the dispersant makes the charges on the surfaces of the two pigment particles different, causing the particles to repel each other; on the other hand, it connects a certain amount of pigment particles through the saturated adsorption layer adsorbed on the surface of the pigment particles to control flocculation.

3. Improve paint leveling

Leveling is the spread of paint on a specific surface Ability. Brush marks in decorative paint are usually caused by insufficient leveling. The leveling performance of coatings is greatly affected by pigments and fillers. After pigments and fillers are introduced into the system, the particles are affected by chemical bonds and physical interactions, making the system unstable and prone to thixotropy and pseudoplasticity, which affects the leveling performance of the paint. When the dispersant is added, the pigment particles are more stable under the action of the polymer dispersant and the leveling properties are improved.

4. Prevent floating colors and blooming

In the process of making paint, blue, Black paint tends to float and bloom. This is because if there is no good wetting, the density, particle size, and movement speed of the particles of these two colors are very different from those of titanium dioxide. One pigment will sink due to gravity and the other will float, resulting in floating colors. If both particles are well moistened, the random movement of the particles will make the paint uniform and the phenomenon of paint floating and blooming will be improved.

5. Improve the tinting power of the medium color paste of the paint

For In paints, the addition of polymer dispersants can reduce the average particle size of pigments to improve tinting strength. The dispersant increases the collision stability of finer particles and prevents flocculation, thereby giving full play to their inherent coloring strength.

6. Increase the content of pigments and fillers

In water-based coating formulations, when pigments As the content of filler increases, the collision of particles during beating will also increase accordingly, which reduces the kinetic energy of dispersion, increases the viscosity of the slurry, and increases energy consumption. Adding a dispersant can disperse higher pigment and filler content, break the particles more quickly, and prevent the viscosity from increasing during the grinding process. In this way, on the one hand, higher pigment and filler content can be dispersed, on the other hand, the dispersion time can be shortened and energy consumption can be reduced.

7. Improve the gloss of the paint

The larger the particle size contained in the paint, the The smaller, the higher the glossiness. Large particles in the coating either cannot be effectively dispersed, flocculate, or stimulate crystallization during the formulation process. Polymer dispersants can avoid the formation of large particles due to flocculation and improve coating films.

8. Improve the hiding power of paint

Light reflects and passes through the surface The quantity determines the hiding power of the paint, and the type of pigment and degree of dispersion have an impact on this. For white paint, the addition of polymer dispersants can reduce the agglomeration of pigments and fillers such as titanium dioxide, reduce the particle size to increase the surface area, and further improve the hiding power.