This time, we will discuss the effects of pigment dispersants on the following properties of coatings: gloss, transparency, compatibility, leveling, production, dyeing strength and VOC reduction.
This is an indicator of film properties. The higher the gloss, the stronger the reflection.
For the gloss of high quality coatings, the particle size should not be greater than 5 microns, the maximum is 3 microns. Ink should not exceed 1 micron. Large particles in coatings can not be effectively dispersed, flocculate or stimulate crystallization in the preparation process. Polymer dispersants can also reduce the formation of large particles due to flocculation and improve gloss.
This is one of the characteristics of the coating. The higher the transparency, the easier it is to see the bottom layer. The higher the covering force is, the stronger the covering force is. The amount of light reflected and passed on the surface determines the covering power or transparency of the paint. The type and dispersion of pigments have an effect on this. Because of the influence of refractive index and particle size, the covering pigment has more influence on the reflected light.
Polymer dispersants improve transparency by affecting the particle size distribution of pigments (more uniform and narrower). For titanium dioxide, high refractive index and large particles can effectively reflect and refract light of various wavelengths. The addition of polymer dispersant can increase the surface area (reduce aggregates, reduce particle size), and further improve the covering power. For transparent pigments, polymer dispersants improve particle size distribution to allow more light to pass through (increase transparency).
Compatibility is important because good compatibility enables paint manufacturers to produce dispersions for a variety of resin products. Polymer dispersants can increase the concentration of pigments, not only increase production, but also reduce potential media incompatibility problems from abrasive pastes to final products. Therefore, especially under the condition of using high compatibility resin, polymer dispersant enlarges the application scope of basic coatings. This is very important for the production of mixed coloring coatings.
Leveling is the ability of coatings to diffuse on specific surfaces. Surface defects of coatings are usually caused by surface tension and occur relatively quickly. The brush marks of decorative coatings are usually caused by insufficient leveling. The ideal flow parallelism can be explained by Newtonian mechanics. But when the pigments are introduced into the system, they will change. This is because particles are very prone to thixotropy and pseudo plasticity due to chemical bonds and physical interactions.
Because the pigment particles are more stable under the action of polymer dispersant and the leveling property is increased, the Newtonian fluid properties can be improved. Convection is beneficial.
Output refers to the amount of paint and ink produced in a process. Dispersants can increase the concentration of pigments and increase the output of coatings. Proper addition of polymer dispersant can reduce the viscosity and increase the pigment content of abrasive paste, thus increasing the output. In a fixed time, more pigments can be dispersed so that more products can be produced with the same weight of abrasive paste. Obviously accelerating the dispersing speed can also increase the output. With the increase of output, the wear and tear of the machine will be reduced and the energy consumption will be reduced, especially the labor cost and fixed cost of the final product per kilogram.
06 Coloring strength
The color intensity of coatings indicates the intensity of the color phase on the applied surface. Improving the dyeing strength of the paint will make it look brighter and more attractive to customers. The optimal grinding conditions can be created by balancing various opposing factors. Reducing the average particle size of pigments can improve the dyeing strength.
Increasing the content of pigments in the abrasive paste will increase the collision of particles and the breakage rate of pigments, but also increase the viscosity, reduce the kinetic energy of abrasive grinding, and reduce the breaking ability of abrasive pellets or beads to pigments. The use of polymer dispersants can change this change. The use of dispersant can grind higher pigment concentration, make particles break up more quickly, and prevent the increase of viscosity in the grinding process. Ultimately, dispersants increase the collision stability of finer particles without flocculation, thus giving full play to their inherent dyeing strength.
VOC, or volatile organic compounds, refers to the organic solvents volatilized into the air in the system. The lower VOC, the less potential air pollution. This requires that the solid content of the coating be increased.
The viscosity of coatings is determined by solvents, resins and pigments. For ordinary low solid content coatings, the effect of pigments on viscosity is not as great as that of resin solvents. However, the high solid content paint solvent is less, the resin is low viscosity, so the influence of pigments is very obvious.
Polymer dispersants significantly reduce the influence of pigments on viscosity by reducing the mutual attraction between particles. Therefore, for high solid content coatings, the addition of dispersants will greatly reduce the viscosity, or, in the same viscosity conditions, will use fewer solvents.