NEUMAN & ESSER has developed an additive dosing and dispersing system that offers several advantages and reduces additive consumption by up to 60 %. The system is called "NEAddiX" and has been tested under real conditions in the powder coating industry.
Additives such as aluminum oxide (AL₂O₃) or silicon dioxide (SiO₂, silica) are used in powder coating processing for better flowability of the solid particles and thus to avoid spitting during application. Costs of the additives are a major factor in powder coating production. These costs can be decreased by enhancing the additive dispersion in the powder and thus reducing the required number of additives while maintaining the desired flowability.
There are a few additives used in powder coating, such as levelling agents, structural additives, matting agents, flow agents and waxes to influence the surface. Most additives are appended to the premix and intermixed into the formulation during extrusion. Additives that influence the flowability, such as aluminum oxide and silicon dioxide (silica), are mixed with the powder after extrusion. These are known as post-blend additives and are then added either before, after or during grinding. [1]
Primary for the application of powder coating is the flowability. The additives, mainly aluminum oxide and silica, facilitate easy transport, avoids spitting during application, and thereby surface defects. Aluminum oxide also improves storage stability, prevents moisture absorption of powder coatings and improves the edge coating of the substrates. In addition, it increases the electrostatic positive chargeability of tribo powders. [2]
Usually about 20 t – 50 t additives per 10.000 t powder coating are consumed. The target is to reduce the required amount of aluminum oxide or rather of silica during the production. Also, the white spots on powder coating surfaces have to be at least significantly reduced if not avoided.
