Fabrication of Ag⁺, Cu²⁺, and Zn²⁺ Ternary Ion-Exchanged Zeolite as an Antimicrobial Agent in Powder Coating

There is an increasing interest to enhance resistance to pathogens on the powder-coated surface. Traditional silver antimicrobial agents are hard to endure high curing temperature and lead to the yellowness of the surface appearance. Commercial sources usually cut down silver loading (less than 2.5 wt %) to avoid the color change and this will result in a low inhibitory effect and poor durability. To improve the antimicrobial performance and maintain the appearance, Ag⁺, Cu²⁺, and Zn²⁺ ternary inorganic antimicrobial agents on Linde A zeolite supports were prepared in this study. The silver content of this agent is increased to 8-10 wt % and the coated surface exhibits high antimicrobial efficiency. The coating appearance shows a little adverse color change ( "E = 1.47) when adding 2 wt % amount of agent. The reduction rate of this agent was over 99.99% after 6 h for Escherichia. coli, Staphylococcus aureus, and Candida albicans according to the ASTM E2180-07 standard, and the paint film can maintain over 99% reduction rate even for 11 cleaning cycles. X-ray photoelectron spectroscopy results show that Cu²⁺ is the main reduced ion during the curing process, which protects Ag⁺ from reduction. The leaching test confirms Zn²⁺ increases the number of extra exchangeable cations, which can prolong the antimicrobial durability. The selected molar ratio of Ag⁺, Cu²⁺, and Zn²⁺ is 1:2:3 according to quantitative study. Moreover, the addition of fillers and pigments was slightly increased the color change of the coated surface.