What does antimicrobial mean?
The term “antimicrobial” covers all working principles with which the growth of bacteria, fungi and viruses is inhibited, colonisation is counteracted from the outset or microorganisms are killed. The effect of antimicrobial coatings is limited to the material surface whose colonisation with germs is to be prevented. Coatings based on polymeric binders (e.g. acrylates, epoxy resins, polyurethanes) fall under the category of plastics. Thus, the same requirements apply to the proof of antimicrobial efficacy of coatings with polymeric binders as for plastics.
How is antimicrobial efficacy defined?
The effectiveness of an antimicrobial surface is defined by the germ reduction achieved within the contact time. This is given in log levels, whereby a log level corresponds to the reduction of germs by one power of ten (log10). Depending on the application of the materials, e.g. in food processing companies or in the medical sector, there are different requirement profiles. For example, plastic surfaces that come into contact with food over several days should have measurable germ reduction values of 3 log levels (= 99.9 %) in relation to a possible bacterial infestation, based on a contact time of 24 hours or less. As a general rule, antimicrobial substances used in coatings should be targeted. They should be incorporated into the coating and surface matrix of the paint in such a way that washing out via cleaning and disinfection measures is avoided as far as possible.
Antimicrobial surfaces are particularly useful in food production, but also in infection prevention, as they can significantly reduce the transmission of viruses and bacteria.