Antibacterial and Scratch Self-Healing Properties of Tea Tree Oil/Tung Oil Dual-Microcapsule Composite UV Wood Coatings

Toenhance the antibacterial properties and scratch self-healing ability of UV wood coatings, in this study, a chitosan–gum arabic composite wall material was used, and tea tree oil and tung oil were used as core materials to prepare tea tree oil antibacterial microcapsules and tung oil self-healing microcapsules, respectively. The two types of microcapsules were then co-added into the UV coating to construct a dual-microcapsule composite functional coating. A three-factor, two-level orthogonal experiment was adopted to investigate the effects of the tung oil self-healing microcapsule addition amount, tea tree oil antibacterial microcapsule addition amount, and coating dosage on the color difference, gloss, antibacterial properties, and scratch self-healing properties of the coatings. Antibacterial test results showed that when the mass fractions of both types of microcapsules were 5%, sample 3-1# exhibited antibacterial rates of 72.0% against Escherichia coli and 83.6% against Staphylococcus aureus; when the tea tree oil antibacterial microcapsule addition amount was 10%, the tung oil self-healing microcapsule addition amount was 5%, sample 3-2# achieved the highest antibacterial rate against Staphylococcus aureus, reaching 85.0%. Scratch self-healing tests showed that when the tea tree oil antibacterial microcapsule addition amount was 10%, the tung oil self-healing microcapsule addition amount was 10%, sample 3-4# had the highest average self-healing rate of 11.79%; when the tea tree oil antibacterial microcapsule addition amount was 5%, the tung oil self-healing microcapsule addition amount was 10%, sample 3-3# had an average self-healing rate of 11.44% and a more balanced healing effect. Range analysis indicated that the effect of the tung oil self-healing microcapsule addition amount on scratch healing was numerically greater than that of the other two factors, but ANOVA showed that the effects of the tung oil self-healing microcapsule addition amount, tea tree oil antibacterial microcapsule addition amount, and coating dosage on the self-healing rate did not reach a significant level (p > 0.05). Considering the color difference, gloss, antibacterial properties, and scratch self-healing properties comprehensively, the self-healing microcapsule addition amount was the core variable affecting the comprehensive performance of coating appearance, antibacterial activity, and self-healing, followed by coating dosage, while the antibacterial microcapsule addition amount had the weakest influence. This study provides an experimental basis for the application of natural active component microcapsules in UV wood coatings with both antibacterial and self-healing functions.