It is 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 settling 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 ability of paint to spread on a specific surface. 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
When making paint, blue and black paint tend 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 colored paints, the addition of polymer dispersants can reduce the average particle size of the pigment to improve the 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 formulas, when the content of pigments and fillers increases, the collision of particles during beating will also increase accordingly, reducing the kinetic energy of dispersion and increasing the viscosity of the slurry. , also 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 paint gloss
The smaller the particle size contained in the paint, the higher the gloss. 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 paint hiding power
The amount of light reflected and passed through the surface determines the hiding power of the paint, and the type and degree of dispersion of the pigment 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.
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