UV Light-Curable Epoxy Coatings with Natural Plant-Based Fillers—Evaluation of Antibacterial and Functional Properties

This article presents the results of research on UV-curable epoxy coatings developed with selected plant modifiers such as garlic (<i>Allium sativum</i>), turmeric (<i>Curcuma longa</i>), common nettle (<i>Urtica dioica</i>), and privet (<i>Ligustrum vulgare</i>). This study aimed to evaluate the influence of these natural components on the functional properties of UV-cured coatings and to assess their potential as bio-based modifiers. The coatings were formulated using Epidian^® 5 epoxy resin, a safe and non-toxic material approved for food-contact applications, and cured with a commercial cationic photoinitiator. Their mechanical, surface, optical, and antibacterial properties were investigated. The results showed that all plant-based additives modified both the mechanical and esthetic characteristics of the coatings; however, garlic demonstrated outstanding antibacterial activity, achieving nearly complete inhibition of <i>Staphylococcus aureus</i> growth with a reduction rate of 99.998%. These findings highlight that natural modifiers, especially garlic, can serve as highly effective functional components, while future work should focus on implementing these coatings for surfaces exposed to bacteria, such as public utility items and shop, hospital, sports, and rehabilitation equipment.