Effect of Blending of Shellac, Carbonyl Iron Powder, and Carbonyl Iron Powder/Carbon Nanotube Microcapsules on the Properties of Coatings

Nine sets of orthogonal experimental samples were prepared by examining four factors: shellac microcapsules, carbonyl iron powder (CIP) microcapsules, CIP/ carbon nanotube (CNT) microcapsules, and primer coating thickness. By testing the morphology and performance of the coating and using the fracture elongation of the coating as an orthogonal experimental analysis, the maximum factor affecting the fracture elongation of shellac, CIP, and CIP/CNT microcapsule coatings was determined. The first two factors that had a significant impact on the fracture elongation of the coating were the content of CIP/CNT microcapsules and shellac microcapsules. In order to further optimize the coating performance, important factor experiments were conducted, using the content of CIP/CNT microcapsules and shellac microcapsules as variables. It was found that the coating had the best performance when the content of CIP/CNT microcapsules was 7.0% and the content of shellac microcapsules was 4.0%. The optical properties of coatings with added shellac, CIP, and CIP/CNT microcapsules were tested, and the color difference and glossiness of the coatings showed little change. The mechanical properties of coatings with added shellac, CIP, and CIP/CNT microcapsules were tested. The blending of the three types of microcapsules enhanced the toughness of the coating to a certain extent, and suppressed the generation of micro-cracks, demonstrating a good self-healing effect. The electromagnetic-absorption performance of coatings with added shellac, CIP, and CIP/CNT microcapsules was tested. The blending of shellac, CIP, and CIP/CNT microcapsules exhibited two effective bands of electromagnetic absorption and a good absorption performance at a relatively wide frequency range. The combination of shellac, CIP, and CIP/CNT microcapsules endows the fiberboard surface with self-healing and electromagnetic-absorption functions, while maintaining the original performance of the water-based coating. The results can be used for application of surface coatings on wooden materials with dual functions of self-healing and electromagnetic absorption.