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 (ΔE = 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.