Preparation and performance of thermochromic and self‐repairing dual function paint film with lac resin microcapsules and fluorane microcapsules

Abstract

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 prop-erties, 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 color-less 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 micro-capsules had a better crack inhibition effect. The results have provided a reference for multifunc-tional wood coatings.