Preparation of Tea Tree Essential Oil–Chitosan Microcapsules and Its Effect on the Properties of Water-Based Coating

The main chemical components of tea tree essential oil (TTO) are monoterpene compounds, including terpine-4-ol,1,8-cineole, para-cymene and γ-terpene. Among them, terpine-4-ol and 1,8-cineole are the main antibacterial components. The microcapsules were prepared by orthogonal experiments with the core-wall ratio, emulsifier concentration, mass ratio of Tween-80 to SDBS and oil-water ratio as variables. Through the analysis of the yield and coverage rate of nine kinds of microcapsules, the concentration of emulsifier was determined as the most influential factor for TTO-chitosan microcapsules, and six kinds of microcapsules were prepared by a single-factor experiment. With the increase in emulsifier concentration, the antibacterial rate of Escherichia coli increased first and then decreased, the antibacterial rate of Staphylococcus aureus increased first, decreased and then increased, and the antibacterial effect of Staphylococcus aureus was better than that of Escherichia coli. When the emulsifier concentration was 4% (13# microcapsule), the overall performance of the coating was better, the microcapsule dispersion was the most uniform, showing a round spheroid shape, and the particle size was mostly distributed between 4 and 8 μm. The antibacterial rate against Escherichia coli was 72.95%, and the antibacterial rate against Staphylococcus aureus was 75.81%. The color difference was 2.77, the glossiness at a 60° incidence angle was 22.8 GU, and the visible light transmittance was 87.80%. The roughness was 0.304 μm, and the elongation was 17.47%. The research results provide a technical reference for the application of an antibacterial water-based coating on a wood surface.