Green chemistry initiatives are driving innovation notably in the coatings market. Requests are increasing for raw materials from renewable feedstocks, less harmful solvents and final products that break down to be easily recycled and nontoxic to the environment. Whether your customer is creating new resins for adhesives, or a water-based (WB) formulation for a pigment grind, an overhead stirrer is integral equipment for coatings development. Successful models include the Caframo Ultra Torque BDC1850 or Universal Torque BDC3030 – both deliver the high torque mixing required by resin cuts and high solids pigment WB systems, combined with the speed range for blending inks or polymers in a latex paint.
The A164 dispersion blade is very popular for coatings, providing the high shear dispersion forces needed for breaking up agglomerates. The A164 also is lab scale version of dispersion blades used at production scale, which supports scale-up with comparable grinding conditions. A common scale up factor used in coatings is the impeller’s tip speed, a function of the diameter and impeller rotation speed. Pitched blade turbines and propellers such as the A561 and A166 are popular for adhesives, paint polymers, and the letdown phase (mixing resin, solvent and additives to the pigment grind).
When mixing for coatings, especially paints in final formulation, key goals are to create a small vortex while mixing, keeping rpm low-moderate to avoid aeration, bubbles and foaming. Another mixing goal is to ensure continuous movement of material at the surface, so additions to the formulation are being drawn in to blend thoroughly.
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