Fabrication and Performance of Thermally Triggered Active Fire-Extinguishing Patches Based on Perfluorohexanone Microcapsule-Modified Epoxy Resin

To address the challenges of timely detection and local suppression of incipient fires, as well as the inherent limitations of traditional flame-retardant materials that primarily rely on passive thermal insulation or combustion retardation, this study developed thermally responsive microcapsules with perfluorohexanone as the core material and melamine–urea–formaldehyde (MUF) resin as the shell. These microcapsules were incorporated into an epoxy resin matrix to fabricate active fire-extinguishing patches. The morphology, chemical structure, thermal stability, thermally triggered release behavior, and fire-extinguishing performance of the microcapsules and the composite patches were systematically characterized by microscopic observation, FTIR, XPS, TGA particle size analysis, and combustion tests. The results showed that the prepared microcapsules exhibited a nearly spherical morphology with a median particle size (D50) of 143.94 μm and an encapsulation efficiency of 87.78%. After heating at 60 °C for 24 h, the mass loss was 5.88%, and after sealed storage at room temperature for 360 days, the mass loss was only 1.8%, indicating satisfactory thermal stability and storage stability. When the microcapsules were compounded with epoxy resin, the self-extinguishing time of the resulting patches decreased with increasing microcapsule content, reaching a minimum of 4.81 s. Mechanism analysis suggested that the fire-extinguishing effect of the composite system originated predominantly from gas-phase flame inhibition by the released perfluorohexanone, possibly synergized with a condensed-phase barrier effect derived from the charring epoxy matrix upon heating. This work provides experimental evidence for the application of perfluorohexanone-based active fire-extinguishing composites in proactive fire protection.