Tung Oil Microcapsules Prepared with Different Emulsifiers and Their Effects on the Properties of Coating Film

Abstract

In water-based coatings, the addition of tung oil microcapsules coated with urea formaldehyde resin (UF) can effectively repair the microcracks in the coating film on the surface of wood. The tung oil as a repairing agent plays an important role in the preparation of microcapsules. In this paper, Span-80, SDBS, OP-10, Tween-80 and SDS were used as five emulsifiers to study the influence of different emulsifiers on the preparation of tung oil microcapsules, and the properties of the coating film added to the waterborne coatings. According to the coating process of three bottoms and three sides, tung oil microcapsules were added to the water-based paint with a content of 12% and coated on the wood surface. The appearance and microstructure of the microcapsules, as well as the mechanical, optical and self-repairing properties of the paint film were analyzed to find out the best emulsifier suitable for the core material. The tung oil microcapsules prepared by Tween-80 have the best morphology, concentrated particle size distribution, particle size of 6–15 μm, and spherical morphology. The film with the microcapsules prepared by Tween-80 had the best performance, small color difference, high gloss, hardness of 5H, adhesion grade 1, elongation at break of 47.23%, impact resistance of 20 kg∙cm, and good toughness. At the same time, the repair rate reached 37.9%. The results provide the application reference for the use of self-repairing microcapsules in coatings.