Thermochromic microcapsules were prepared with a thermochromic compound as core material and urea formaldehyde as wall material. The molar ratio of urea and formaldehyde, the mass ratio of core material to wall material, the concentration of emulsifier, and rotating speed were selected to make a four-level and three-factor L₉(3⁴) orthogonal test. It was found that the molar ratio of urea and formaldehyde had the greatest influence on the coating rate of microcapsules. The effects of molar ratio of urea and formaldehyde on the discoloration temperature and coating rate of microcapsules were studied. When the molar ratio of urea to formaldehyde was 1:1.6, the core material: wall material ratio was 4:7, the concentration of emulsifier was 5.0%, and the rotating speed was 1600 rpm, the performance of the microcapsules was the best. When the microcapsule content was 20.0%, the color difference of the paint film was the largest, the gloss and hardness of the paint film decreased with increasing microcapsule content, and the impact resistance of the paint film first increased and then decreased with increasing microcapsule content. The adhesion of the paint film remained unchanged, and was grade 1. When the microcapsule content was 20.0%, the performance of the paint film was at its best. This provides a basis for the application of thermochromic coatings.

In this paper, a thermochromic complex was prepared from crystal violet lactone (CVL), bisphenol A (BPA) and tetradecanol. The color-changing temperature of the color-changing compound was found to be 25 °C by orthogonal experiment. Microcapsules coated with a thermochromic compound were added into alkyd resin at different mass concentrations. With the increase in temperature and mass fraction of microcapsules in the coating, the color difference of the coating showed an upward trend. The highest variation in the coating’s color difference occurs when there were 10% microcapsules. When the mass fraction of microcapsules was 15.0~25.0%, there was little change to the gloss of the coating. With the increase in the mass fraction of the coating microcapsules, the hardness of the coating gradually increased. The hardness was at its best when the microcapsule concentration was 25%. When the microcapsule concentration was 20%, the impact resistance of the coating was at its best. The coating had good cold-liquid resistance to acetic acid, ethanol, and NaCl solutions, and there was basically no mark on the coating surface before and after the cold-liquid-resistance test. The addition of microcapsules did not change the chemical composition of the coating, and it improved the performance of the coating. When the microcapsule concentration was 10%, the overall performance of the coating was at its best, which laid the technical foundation for thermochromic coating on the metal surface.

A coating with thermochromic and photochromic microcapsules can enhance a product’s attractiveness. Different coating processes may affect the performance of coatings. Therefore, the micromorphology, chemical composition, chromatic difference, gloss, hardness, adhesion, impact resistance, roughness, cold liquid resistance, and ultraviolet photooxidation resistance of the surface coating on the metal substrate were assessed by choosing three coating processes. The thermochromic color difference of the coating with photochromic microcapsules in the primer and thermochromic microcapsules in the topcoat changes greatly. When the temperature reached 80 °C, the maximum color difference of the coating was found to be 23.0. The color difference of the coating with the thermochromic microcapsules in the primer and photochromic microcapsules in the topcoat was the most obvious, with a color difference of 71.7. The gloss of the coating mixed with thermochromic microcapsules and photochromic microcapsules was the highest, which was found to be 81.7 GU. The coating gloss of thermochromic microcapsules in the primer and photochromic microcapsules in the topcoat was found to be 15.6. The mechanical property of the coating mixed with thermochromic microcapsules and photochromic microcapsules was the best—the hardness was found to be 2H, the adhesion was found to be level 1, and the impact resistance was found to be 12.5 kg·cm. The mechanical property of the coating prepared by the other two coating sequences was poor. The coating prepared by the three finishing processes on the metal substrate had sufficient cold liquid resistance, and the gloss of the coating before and after the cold liquid resistance changed slightly. By studying the coating process of thermochromic coating and photochromic coating, a technical reference is provided for creating dual-function intelligent coatings.

Microcapsules with lac resin as the core material and urea-formaldehyde resin as the wall material were prepared by in situ polymerization, and then the lac resin microcapsules and fluorane microcapsules were added into a water-based primer or topcoat, respectively, to prepare water-based coatings with dual functions of thermochromic and self-repair. The effects of different methods of adding microcapsules on the optical properties, mechanical properties, self-repairing properties, and the aging resistance of water-based paint film were investigated, so as to prepare water-based paint film with the best discoloration and self-repairing functions. The results showed that the paint film with 10.0% fluorane microcapsules in the topcoat and 5.0% lac resin microcapsules in the primer had better comprehensive properties, and the paint film changed from yellow to colorless at 32 °C, with a color difference of 68.9, hardness of 3H, adhesion grade of 0, impact resistance of 13.0 kg∙cm, and elongation at break of 20.0%. The resistance of the paint film to NaCl, ethanol, and detergent was grade 2, with slight discontinuous marks, and the resistance to red ink was grade 3, with slight marks. The lac resin microcapsules have good aging resistance, which can enhance the aging resistance of the paint film with fluorane microcapsules. The gap width of the paint film was repaired by 2.1 µm, the self-repairing rate was 12.3%, and the paint film with lac resin microcapsules had a better crack inhibition effect. The results have provided a reference for multifunctional wood coatings.

With the development of the economy and science and technology, consumers have put forward higher requirements for the functionality of surface coatings on wood products and metal products, which requires us to endow traditional coatings with new functions. Innovative research of coatings has been a research hotspot in recent years, and the combination of microencapsulation technology with coatings is a research direction attracting much attention. In this paper, a kind of spirooxazine color-changing microcapsules containing photochromic purple dye was selected to explore the effect of different loadings of the photochromic microcapsules on the properties of the coatings. The photochromic microcapsules were added to the waterborne coating with loadings of 5.0%, 10.0%, 15.0%, 20.0% and 25.0%. The coatings were coated on Tilia europaea boards and aluminum alloy plates to explore the optical properties, mechanical properties, cold liquid resistance and aging resistance of the coatings. The results showed that the coating had good photochromic property on wood substrate and metal substrate. When the loading was 15.0% and 10.0%, the comprehensive performance of the coating was good. The color difference of the coating before and after photochromism was 51.0 and 62.0, the glossiness was 7.1% and 15.9%, the hardness was 3H, the adhesion grade was 1, the impact resistance was 4 kg·cm, the roughness was 1.2 μm and 0.9 μm and the liquid resistance grade was 1. The research results show that the photochromic microcapsule can endow the paint with a reversible color change function and improve some mechanical properties of the coating, which indicates that the composite prepared in this study can be used in the surface finishing of wood and metal and has certain research value and application potential.

The fluorane thermochromic microcapsules and waterborne acrylic resin microcapsules were added into waterborne coatings at the same time to prepare intelligent waterborne coating film with dual functions of color change and self-repairing. The coating film prepared by adding 15.0% fluorane microcapsules and 5.0% waterborne acrylic resin microcapsules to the primer at the same time had better comprehensive properties. At this time, the coating film changed from yellow to colorless. The repair rate of the coating film was 58.4%. When the temperature was lower than 32 °C, waterborne acrylic resin microcapsules can improve the thermochromic performance of the coating film with fluorane microcapsules. Waterborne acrylic resin microcapsules can alleviate the color change of coating film with fluorane microcapsules. The fluorane microcapsules can improve the self-repairing performance of coating film with waterborne acrylic resin microcapsules. The results lay a theoretical and technical foundation for multifunctional coating film.