Key points in pigment stabilization are an effective and durable adsorption of pigment-anchoring groups from the dispersing additive on the pigment surface, while the additive’s side chains exhibit outstanding compatibility with the surrounding matrix. Minimizing pigment-pigment interaction by shielding the particles due to steric hindrance can only be achieved if the polymeric side chains of the additive provide high solvency, thereby stretching and protruding into the liquid system. In contrast, non-sufficient compatibility will result in coiled side chains, reduced pigment particle spacing and flocculation. Stabilized pigment particles are one pre-requisite for achieving long-term stability, low mill-base viscosities, high gloss and high transparency, along with optimal color strength in the applied coating.
The pigment-adsorbing groups in dispersing additives are chosen to interact effectively with as many pigment classes as possible, e.g., inorganic pigments, organic pigments and carbon blacks. Due to the fact that as the particle size of the pigments gets smaller and their surface area simultaneously becomes greater, the design of a suitable dispersing additive must be tuned in such a way that the molecular weight is high enough to provide effective particle shielding to avoid flocculation. Additionally, the number of pigment anchoring groups needed must be optimized to generate a durable and long-lasting adsorption layer at the pigment surface.