Effect of charring agents on solvent-free fireproof coatings

The choice of charring agent is one of the major issues for solvent-free fireproof coatings. The effects of processing method and charring agent on the thermal insulation and fire resistance of the coatings were investigated in simulated fire scenarios. Dipentaerythritol (DPER), triazine agent (CFA), and pentaerythritol phosphate (PEPA) were compared as charring agent, and the thermal, combustion, fire resistance, and charring behaviors in different fire scenario were characterized for the fireproof coatings. Compared with high-speed dispersing equipment, kneading processing equipment is favorable for improving the thermal stability and fire resistance of the coatings, because the stronger shearing force has promoted mixing and dispersion of the ingredients in solvent-free fireproof coatings. As for charring agents, it is found that the fireproof coatings containing CFA or PEPA show better thermal and flame-retardant performances. More residue was observed under nitrogen atmosphere in thermogravimetric analysis, less heat and smoke were released in cone calorimetry test. However, during the high temperature fire resistance test, their char layers were prone to delaminate while DPER-containing coatings produced intact and stronger char layer with better heat insulation. For practical applications, the coating formulations need to be optimized to achieve both fire resistance and flame retardancy.