Alcohol degradation of anhydride-cured epoxy resin insulating materials containing SiO2 filler

The anhydride-cured epoxy resin with silica micro-powder (SAE) is widely used in electrical equipment due to its excellent properties. However, its three-dimensional network structure makes degradation and recycling difficult. Conventional disposal methods, such as incineration or landfill waste resources, harm the environment. Therefore, it is crucial to develop a mild degradation and recycling method for epoxy resin. In this study, after evaluating the electrical, mechanical, and thermal properties of SAE, we achieved efficient and mild alcoholysis of high filler content (50%) SAE. This was done using K3PO4 as a catalyst and ethanol as a solvent, with the reaction conducted at 120 °C for 3 h. We also explored degradation optimization at different temperatures, with varying water and filler contents. Results showed a degradation efficiency of nearly 100% under these conditions. Raising the temperature moderately and adding a small amount of water were found to boost the degradation efficiency. The insolubility of K3PO4 in ethanol enabled effective separation and reuse of the catalyst and filler. FTIR analysis confirmed the chemical structure of the degradation products, showing their recyclability. This degradation method allows for efficient degradation of SAE while maintaining or even enhancing its properties compared to pure epoxy resin.