Carbon black is one of the important raw materials for coatings. As a pigment for coatings, carbon black can provide reliable performance improvement in terms of coating color and anti-ultraviolet aging. The influence of the characteristic change of carbon black on the coating process is as follows
1. When the average particle size of carbon black particles decreases, or when the specific surface area increases:
1. Viscosity increases, more resin and solvent are needed, free-flowing coatings have less coating volume, and more leveling aids need to be consumed.
2. The blackness increases, the absorption of light increases, and the reflected light decreases, making people feel darker.
3. Reduced dispersion. The gravitational force between carbon black particles increases, and more milling energy needs to be consumed. High shear forces are required to break up the carbon black aggregates into smaller pigments or individual pigment particles.
4. The gloss of the coating film is reduced. The amount of paint in the paint for reflection is reduced and the amount of resin is increased.
2. When the carbon black structure increases:
1. Reduced blackness. The particles condense into aggregates, which is equivalent to the effect of carbon black with coarser particles
2. As the viscosity of the paint increases, the amount of free-flowing paint decreases and the amount of resin increases.
3. Reduced dispersion. Larger shear forces are required to break the agglomerates.
4. Gloss reduction. Lacquer needs to increase and surface binder to decrease.
3. When surface activity and surface acidity increase:
Blackness increases, viscosity decreases, dispersion increases, and gloss increases. For most resins, when the surface activity and acidity of carbon black particles increase, it means that surfactants and carbon black are added to the paint together, which reduces the surface tension of the liquid-solid interface and improves the leveling of the paint. , the amount of leveling aids is reduced, and a flat and smooth coating film can be obtained.
