Cold bonding method for metallic powder coatings

An efficient and simple method for preparing bonded metallic powder coating is in high demand in the paint manufacturing and application industries. The bonding purpose is to keep the mass percentage of metallic pigment consistent between the original and recycled coating powder, which aims at solving the problem of recyclability. One possible method capable of realizing this goal is using the binder to cohere metallic pigment with base particles through a cold bonding method. Through this approach, the pre-curing and high-reject-rate problems generally present in thermal bonding can be completely eliminated. In this paper, polyacrylic acid (PAA) and polyvinyl alcohol (PVA) are applied as binders for the bonding process. At various dosages of liquid binder and D.I. water, bonded samples with different bonding effect were prepared. Finally, a good bonding quality with the lowest variance between the mass concentrations of Al flakes in the original powder (before spray) and deposited powder (after spray) 2.94% with PAA as a binder and 0.46% with PVA as a binder was achieved. These results manifest that the cold bonding method is a green and simple approach for preparing the metallic powder coating.