A promising strategy for balancing the thermal insulation and char layer strength of water-based intumescent fireproof coating: A synergistic effect between organic-modified titanium dioxide and expandable graphite

Nowadays, endowing water-based intumescent fireproof coatings with balanced thermal insulation and char layer strength is highly desirable in the field of steel structures fire prevention. Herein, a novel water-based intumescent fireproof coating with desired thermal insulation, fire resistance, and char layer strength was developed based on the traditional “APP-PER-MEL” intumescent flame-retardant system and epoxy resin latex, in which the organic-modified titanium dioxide containing B/Si ceramic precursors (MTi) and expandable graphite bearing γ-aminopropyltriethoxysilane (MEG) were added into the above system as functional fillers. Specifically, MTi served as an inorganic reinforcing component to strengthen the intumescent barrier layer, while MEG worked as an expanding component to compensate for the inhibition of the expansion ratio by MTi. Benefiting from the good synergistic flame-retardant effect between MTi/MEG and “APP-PER-MEL” intumescent flame-retardant system, the target fireproof coating obtained excellent fire resistance and heat insulation performance as well as char layer strength. As expected, the target fireproof coating exhibited remarkable thermal reliability and char residue (51.2 wt%), its backside temperature was lowered to 257.9 °C after 20 min of heat insulation test. Importantly, the intumescent char layer of the target fireproof coating could withstand a 100 g weight without collapsing or breaking, its compressive strength reached 10.25 kPa, which was 1267% higher than that of the blank sample. Moreover, the PHRR, THR, and PSPR values of the target fireproof coating declined by 23.8%, 16.7%, and 35.7%, respectively, compared to the blank coating. This work put forward a viable strategy for the fabrication of intumescent fireproof coatings with ideal thermal insulation performance and char layer strength, which can effectively improve the fire safety of steel structural components.