Effect of Urea–Formaldehyde Resin–Coated Colour–Change Powder Microcapsules on Performance of Waterborne Coatings for Wood Surfaces

Microcapsules have received a great deal of attention from researchers due to their excellent properties, and are commonly prepared by interfacial and in situ polymerisation methods. In situ polymerisation is an important method of microcapsule preparation, which has a number of advantages such as low cost and suitability for industrial production. Microencapsulation is used to modify the state of the material in order to improve its practical usability and mechanical and optical properties. In this paper, urea–formaldehyde resin–coated colour–changing powder microcapsules were prepared and their properties were used to study the colour–changing properties of wood surface coatings, and the mechanical and optical properties of waterborne paint films incorporating colour–changing powder microcapsules were tested. The results show that as the microcapsule content increases, the colour–change effect of the coating gradually becomes obvious and the amount of change in the b–value representing the yellow hue gradually increases. As the microcapsule content increased from 1.0% to 13.0%, the b–value increased from 0.7 to 2.6. The gloss of the film decreased significantly with the increase in the microcapsule content of the colour–change powder, with the highest gloss at 1.0%. The impact resistance of the film was also influenced by the content of microcapsules in the waterborne topcoat, with the best impact resistance at 5.0%, level 2 of adhesion at 1.0%–5.0% and 11.0%–13.0%, and level 1 of adhesion at 7.0% and 9.0%. In terms of mechanical and optical properties, the 5.0% content of colour–changing powder microcapsules is the best for the overall performance of waterborne topcoats. In practical furniture applications, the microcapsules prepared in this paper can change the colour in appearance according to the actual temperature and play a decorative role.