## 3 Results and Discussion
### Influence of Coating Processes on the Performances of Waterborne Coatings Containing Microcapsules
#### 3.2.4 Analysis of Microstructure and Infrared Spectrum of Coatings
This is because the wood itself will carbonize to change the chromatic aberration in the high temperature environment. In addition, the microcapsules will break and release the core material from the milky yellow microcapsule during the aging process, increasing the protection of the coating on the wood surface. Therefore, the chromatic aberration is changed indistinctively. Figure 5: Infrared spectrum of paint film on three times of primer and two times of finish. When the coating was at 120 \({}^{\circ}\)C, as shown in Figure 9, the light loss rate of the coating without microcapsule reached 19.65% for 40 h, and that of the coating with microcapsule addition of 6.0% was 2.13% for 40 h. It indicates that the gloss of the paint film decreases only slightly. As shown in Figure 10, when the coating was at 160 \({}^{\circ}\)C, the light loss rate of  
Figure 8: Influence of time on chromatic aberration of coating under UV weather resistance test. Figure 6: Influence of time on chromatic aberration of coating under 120 \({}^{\circ}\)C aging test. Figure 7: Influence of time on chromatic aberration of coating under 160 \({}^{\circ}\)C aging test. the coating without microcapsules reached 45.85% for 40 h, and the light loss rate of the coating with 6.0% microcapsules reached 16.63% for 40 h. As shown in Figure 11, when the coating was in the UV weather resistance test, the light loss rate of the coating without microcapsule was 19.21% for 40 h, and the light loss rate of the coating with microcapsule addition of 6.0% was 3.80% for 40 h. The results show that the light loss rate of the coating increased with the increase of aging time. During the aging process in the oven at 120 \({}^{\circ}\)C, the light loss rate decreased slightly from 24 h to 32 h. It may be because the microcapsule breaks caused by the micro crack on the coating surface, and the outflow of core material has the excellent repair effect on the coating. At this time, the repair effect was higher than the aging cracking strength of the coating, which reduced the gloss loss of the coating. After 32 h, the aging strength was still increasing, while the number of microcapsules with the repair effect in the coating decreased, resulting in the gradual decrease of overall repair strength and the increase of light loss rate. During the aging process in the oven at 160 \({}^{\circ}\)C and UV climate resistance test chamber, with the too-high aging strength, the microcapsules could also improve the aging resistance of the coating. The plant fiber, which is the composition in the microcapsule wall material, enhanced the toughness of the coating, fundamentally reducing the generation of cracks in the coating during the aging process. The microcapsules distributed in the coating broke under stress after the cracks occurred. The repair agent, as the core material, flowed to the crack to inhibit the generation of crack. This made the light loss rate of the coating surface increase slowly, while the coating without microcapsules did not have this ability. Figure 10: Influence of time on light loss rate of coating at 160 \({}^{\circ}\)C in oven. Figure 9: Influence of time on light loss rate of coating at 120 \({}^{\circ}\)C in oven. The SEM images of the coatings without microcapsules and with 6.0% microcapsules in which wall material contained 5.5% rice husk powder after aging test in the oven at 120 \({}^{\circ}\)C, at 160 \({}^{\circ}\)C and UV weather resistance test chamber are shown in Figures 12-14. It can be seen that the coating on the wood surface without microcapsules is obviously damaged after the aging test (Figures 12A, 13A and 14A). There are damages and cracks, and the maximum crack size is close to 40-50 \(\upmu\)m. The coating with 6.0% microcapsules is not easy to crack in the aging process (Figures 12B, 13B and 14B). It may be that the waterborne coating with 6.0% microcapsules has the better elongation at break, good toughness and strong environmental adaptability.