Frequently Asked Questions About Pigment Black Dispersion

The pigment carbon black in the carbon black series is a relatively useful pigment in black coatings and paints. However, sometimes due to many reasons, flocculation will occur over time. In order to solve this phenomenon well, we must first understand the flocculation mechanism of carbon black. Among all kinds of pigments, the dispersion of carbon black is the most difficult, due to the extremely strong aggregation between carbon black particles and the high oil absorption. In addition, carbon black, especially pigmented carbon black that has been post-oxidized, generally has a relatively large surface area and can easily absorb moisture in the surrounding environment.
Dispersion is done by forming a resin or polymer coating layer on the surface of the pigment carbon black, so that the original pigment agglomerates form more stable small agglomerates. In other words, for the dispersant to work, it must have sufficient strength with the pigment surface. The affinity or force can form a stronger and more stable adsorption layer on the surface of the pigment, that is, the wrapping layer; at the same time, the solvent and resin in the carbon black dispersion system will also compete for adsorption of the pigment, and the dispersant must also form a higher ratio with the pigment than the resin. Stronger adsorption with the solvent can achieve dispersion.
In addition, to form a stable dispersion system, there must be a long enough solvation chain segment, that is, the dispersant must have an appropriate molecular weight, so that during the storage process of the paint, the carbon black particles will not be damaged due to collisions caused by Brownian motion. Re-flocculate into larger particles or extend the time for flocculation to return to coarse particles.
Under the same formula conditions, if the amount of pigment carbon black is large and the dispersant is insufficient, it will not be able to achieve the optimal dispersion state. Only when the amount of carbon black and the amount of dispersant are adjusted, can the dispersion be good. The gloss is very glossy.