The Effects of Urea–Formaldehyde Resin-Coated Toddalia asiatica (L.) Lam Extract Microcapsules on the Properties of Surface Coatings for Poplar Wood

Urea–formaldehyde resin was used as a wall material and Toddalia asiatica (L.) Lam extract was used as a core material to prepare urea–formaldehyde resin-coated Toddalia asiatica (L.) Lam extract microcapsules (UFRCTEMs). The effects of UFRCTEM content and the mass ratio of core-to-wall material (Mcore:Mwall) on the performance of waterborne coatings on poplar surfaces were investigated by adding microcapsules to the waterborne topcoat. Under different Mcore:Mwall of microcapsules, as the content of microcapsules increased, the glossiness and adhesion of the coatings gradually decreased, and the color difference value of the coatings gradually increased. The cold liquid resistance, hardness, and impact resistance of the coatings were all improved, and the roughness of the coatings increased. The antibacterial rates of the coatings against Escherichia coli and Staphylococcus aureus were both on the rise, and the antibacterial rate against Staphylococcus aureus was slightly higher than that against Escherichia coli. When the microcapsule content was 7.0% and the Mcore:Mwall was 0.8:1, the surface coating performance on poplar wood was excellent. The glossiness was 3.43 GU, light loss was 75.55%, color difference ΔE was 3.23, hardness was 2H, impact resistance level was 3, adhesion level was 1, and roughness was 3.759 µm. The cold liquid resistance was excellent, and resistance grades to citric acid, ethanol, and cleaning agents were all 1. The antibacterial rates against Escherichia coli and Staphylococcus aureus were 68.59% and 75.27%, respectively.