Abstract
In this paper, melamine–formaldehyde (MF) was used as the wall material, and epoxy resin was used as the core material to prepare microcapsules. The optical properties, mechanical properties and ageing resistance of waterborne topcoat were investigated by adding different mass fractions of microcapsules into the waterborne topcoat. Through scanning electron microscopy and infrared spectroscopy analysis, the prepared microcapsules of core-wall ratio of 0.50 were more uniform. It was found that when the mass fraction of microcapsules is less than 10.0% and the core–wall ratio is 0.50, the original color difference of the coating can be maintained. With the increase in microcapsule mass fraction, the gloss of the topcoat film gradually decreases. The mass fraction of the microcapsule of 4.0% with the core–wall ratio of 0.50 can maintain the original gloss of 30.0 GU. The topcoat film with the MF-coated epoxy resin microcapsules of the core–wall ratio of 0.50 has high impact resistance, adhesion and hardness. The results showed that the gloss loss and color difference of the coating with the MF-coated epoxy microcapsules were the lowest when the mass fraction of microcapsules was 4.0%, indicating that microcapsules can improve the stability of coating. These results lay a technical foundation for the development and application of high-performance wood coatings.
Highlights
Microcapsules have attracted widespread attention because they have excellent properties to protect the core material from being changed by foreign objects
Due to the expansion and drying shrinkage of wood substrate, when the surface coating on wood materials is cracked, the wall material will crack, and the core material will flow out the repair agent to fill the microcracks, thereby improving the durability of the paint film and extending the service life [8]
Through scanning electron microscope (SEM) analysis, it was found that the microcapsules with 0.50 of core–wall ratio were more uniform and the surface was smoother
Summary
Microcapsules have attracted widespread attention because they have excellent properties to protect the core material from being changed by foreign objects. The core material covered by the wall material can shield the taste, color, odor, and change the weight, volume, state, or surface properties of the substance. Still, cracking defects are likely to occur in the coating and subsequent use process, resulting in reduced mechanical properties, so self-healing microcapsule technology can be used to repair the cracks [7]. Due to the expansion and drying shrinkage of wood substrate, when the surface coating on wood materials is cracked, the wall material will crack, and the core material will flow out the repair agent to fill the microcracks, thereby improving the durability of the paint film and extending the service life [8]
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