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Specialty Additives Update

April 2011
Defoaming Surfactants for Pigment Dispersion

When preparing an aqueous pigment dispersion, it’s important to control the surface tension with a good surfactant to help enable adequate wetting of the typically hydrophobic pigment powders. Without adequate surface tension control, it may be time- and energy-consuming to cut the powdered pigment into an aqueous solution. Even after incorporation, the pigment particles can remain inadequately wetted—leaving air pockets trapped on or in the agglomerates, causing foam and efficiency problems throughout the milling phase.

At Air Products, we understand that traditional surfactants can cause more problems than they solve when used in a pigment dispersion—from stabilizing foam to impacting dispersion viscosity and stability. With that in mind, we developed a range of Gemini defoaming surfactants, such as EnviroGem® AD01, Surfynol® 104, Surfynol 420, and Surfynol DF110 surfactants, to help you avoid common problems associated with typical surfactant chemistries. These additives can help provide excellent surface tension reduction and wet the most hydrophobic of pigments while not competing with dispersant chemistries during stabilization. Typically, these additives do not have a negative effect on dispersion stability or viscosity. These additives can also function as molecular defoamers, thereby disrupting the foaming tendency that can be caused by other additives.

At the low use levels of 0.05–0.2 wt %, these efficient surfactants can provide the surface tension reduction you need to wet the most demanding pigment powder. This can help you achieve faster cut-in times and outstanding deaeration of the dry particles, which can reduce system foam and improve the milling process.

At slightly higher use levels of 0.2–1.0 wt %, these additives function as molecular defoamers and can provide excellent antifoam performance throughout the milling process. Easy to use and incorporate, these molecular defoamers can be added into your formulation under high or low shear conditions and provide excellent persistence in the formulation without the typical incompatibility defects that you may experience with traditional defoamer chemistries.

EnviroGem AD01 and Surfynol 420 surfactants are 100% active liquids and free of solvents. Surfynol 104 and Surfynol DF110 surfactants are offered as solvent solutions. All are free of APE chemistries. 

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