Investigation of the recyclability of powder coatings

100% recyclability is one of the major advantages of powder coating. However, it can never be achieved in reality. Coating powders, especially finer powders with particle size below 30 μm, were found to have much worse flow performances after recycling from electrostatic spraying so as to decrease the recyclability. Therefore, this study was designed to investigate recycled coating powders to determine the underlying cause of decreased flow performance. The investigations were based upon three major factors that make the differences between original powder and its recycled powder: particle size, humidity exposure and flow additive concentration. By adjusting the three factors independently, the influences to powder flow properties were analyzed. Results showed that the decreased particle size of the recycled powder had the most significant effect on the flow properties. Additive concentration on the powder particles did not change with respect to the particle specific surface area after electrostatic spraying. Humidity had only a minor effect on the flow properties of powder coatings.