Epoxy resin is a hydrogen-based compound. When it reacts with polyurethane, it can introduce its melting point into the main chain of polyurethane to form a network structure, which can significantly improve the performance of various aspects. The effect of epoxy resin addition on waterborne polyurethane coatings is shown in the table.
From the table, we can know that the appearance of waterborne polyurethane coatings gradually changes from transparent to opaque lime water with the increase of the amount of epoxy resin added, and after adding epoxy resin, the water absorption rate of waterborne polyurethane coatings is significantly reduced. It shows that its water resistance is effectively improved. At the same time, with the increase of the amount of epoxy resin added, the viscosity and hardness of waterborne polyurethane coatings also gradually showed an upward trend. However, it does not mean that the more epoxy resin is added, the better, because its cross-linking effect will greatly increase the diameter of water-soluble polyurethane particles. Therefore, the most suitable amount of epoxy resin added should be 5.0%~7.0%.
