Optimal formulation for aqueous dispersions—
Surface Active Additive Triangulation:
The formulation of aqueous pigment dispersions can be enhanced by using stabilizing additives such as dispersants, binders or grind resins. Typically, additional surface active agents are used to improve both the dispersion process and application’s performance. Finding the optimal formulation can be challenging and time consuming, so it is critical to recognize the core functions of the additives and how they work together for optimal performance.
Dynamic wetting provides fast cut-in of dry powders as well as full deaeration of any agglomerates, which can improve milling efficiency. Dynamic stabilization can affect milling efficiency, color development, and stability during letdown. Equilibrium stabilization can prevent flocculation of dispersed particles and is vital for optimal color stability.
These three functions can be visualized as a triangle, where inclusion of all three can lead to dispersion formulations having optimal performance.
The dispersant functions for stabilizing are centered on the right side of the triangle. Combining Ionic polymeric dispersants and nonionic co-dispersants is common for optimal performance and stabilization. Or alternatively, a formulator can choose a high performance dispersant designed to address both performance needs, such as a product from the Air Products ZetaSperse 1000, 2000, or 3000 series of dispersants.
Surfactants are centered on the left side of the triangle. Low HLB wetting agents, like the Surfynol and Dynol surfactants, are designed to provide optimal dynamic wetting characteristics. Dedicated products for pigment dispersion, like the Carbowet GA-series grind aids, are tailored to provide an ideal balance of both wetting and stabilizing characteristics for milling and dispersion performance.
The triangle summarizes the three functions necessary for an optimal dispersion. A chemist can gain significant efficiency in formulation by considering the properties each additive can provide. This can allow faster problem solving and avoid the use of overlapping redundant additives that do not add unique benefits.
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