Preparation of Tea Tree Essential Oil@Chitosan-Arabic Gum Microcapsules and Its Effect on the Properties of Waterborne Coatings

Furniture surfaces are prone to the accumulation of bacteria, fungi and other micro-organisms, especially in humid environments such as kitchens and bathrooms. The antimicrobial treatment of coatings has been demonstrated to enhance the performance of wood, prolong its service life, and improve hygiene and safety. Consequently, by investigating the most effective preparation process for antimicrobial microcapsules and incorporating them into the coating, the coating can be endowed with antimicrobial properties, thereby expanding its application range. Microcapsules were prepared using a composite wall material consisting of chitosan (CS) and Arabic gum (AG), with tea tree essential oil (TTO) serving as the core material. The best CS-AG coated TTO microcapsules were prepared when the core–wall ratio was 1.2:1, the emulsifier concentration was 2%, the pH was 3, and the mass ratio of AG to CS (mAG:mCS) was 3:1. The mAG:mCS was identified as the most significant factor affecting the microcapsule yield and encapsulation rate. With the increase in mAG:mCS, the antimicrobial rate of the coating against Escherichia coli (E. coli) exhibited a trend of first rising and then falling, while the antimicrobial rate against Staphylococcus aureus (S. aureus) demonstrated a trend of first rising, then falling, and then rising again. The colour difference (ΔE) and gloss exhibited an overall downward trend, the light loss rate demonstrated a fluctuating upward trend, and the roughness exhibited a trend of first falling and then rising. The visible light band transmittance exhibited minimal variation, ranging from 86.43% to 92.76%. Microcapsule 14# (mAG:mCS = 3:1) demonstrated remarkable antimicrobial properties (E. coli 65.55%, S. aureus 73.29%), exceptional optical characteristics (light transmittance 92.12%, 60° gloss 24.0 GU), and notable flexibility (elongation at break 18.10%, modulus 0.10 GPa). The waterborne coating was modified by microcapsule technology, thus endowing the coating with antimicrobial properties and concomitantly broadening the scope of application of antimicrobial microcapsules.