Development of antibacterial powder coatings using single and binary ion-exchanged zeolite A prepared from local kaolin

Antibacterial electrostatic powder paint coating with intended esthetic criteria was specially formulated for industrial applications using single (Ag+) and binary exchanged (Ag+ and Zn2+) zeolite A, which was prepared from local kaolin resources. Optimization studies on reaction parameters were conducted to obtain the most crystalline zeolite A from kaolin. The Ag+ and Zn2+ exchanged zeolite A samples prepared from kaolin were introduced as filler into the paint matrix during the electrostatic powder coating process. The antibacterial efficacy of the coatings was evaluated against E. coli and S. aureus based on Japanese Industrial Standard JIS Z 2801 method. Color analysis was also performed on these coatings in order to meet the least discoloration criteria, which is relevant to judge the quality of the coatings for industrial use. Single ion-exchanged coatings with Ag+ resulted in discoloring effect, which was diminished by adding Zn2+. The results indicated that the coatings containing both 2 wt% Ag+ and 12 wt% Zn2+ exchanged zeolite A exhibited 99.99% and 99.96% reduction for E. coli and S. aureus, respectively. This was of special interest for zeolite A samples that were prepared from local kaolin resources with more significant discoloration due to using natural kaolin as raw material. In conclusion, a low cost and antibacterial powder paint formulation with desired esthetic criteria using zeolites was achieved for the first time using a combination of Ag+ and Zn2+ ions.