Study on the effect of film-forming agent composition on moisture and heat resistance of basalt fiber composites

Resistance to hygrothermal aging is the key to the popularization and application of basalt fiber composites in the field of electrical equipment, so it is crucial to develop fiber surface-modified coatings suitable for basalt fibers with excellent hygrothermal resistance. In this study, the performance changes of basalt fiber composite samples treated with four types of surface coatings under artificially accelerated hygrothermal aging test were comparatively analyzed, and the mechanism of different components in the surface coatings was further analyzed. The results showed that the use of epoxy resin emulsion co-mingled with acrylic emulsion as the film-forming agent could significantly improve the mechanical properties of the samples. The use of epoxy resin emulsion co-blended with polyurethane emulsion as the film-forming agent improved the insulating properties and moisture and heat resistance of the samples. Further, the use of 5:1:1 epoxy emulsion, acrylic emulsion, and polyurethane emulsion co-blended as the film-forming agent component can ensure the insulation and hygrothermal resistance of the samples while taking into account the mechanical properties. After 120 hours of wet-heat aging, the breakdown field strength was increased by 22%, leakage current and dielectric loss angle was increased by 10%, and the mechanical properties were also significantly improved compared with the sample with epoxy emulsion as the main film-forming agent. In summary, through the compounding of the film-forming agent emulsion components, the optimization of the moisture and heat resistance of basalt fiber composites can be achieved, and the use of the mass percentage of 5:1:1 for the three types of emulsions blended to prepare the fiber surface coatings is more suitable for the treatment of basalt fibers to prepare the electrician’s equipment.