Discussion Over Forming Process of Charring Layers of Intumescent Fireproof Coating

Forming process of charring layers and its final state were main factors to decide fireproof limit of intumescent fireproof coating for steel structure, therefore how to form light, homogeneous, tight and high strength charring layers was the key technology for study and production of such coatings. Forming process of charring layers of intumescent fireproof coatings was a severe chemical reaction process at high temperature, so it was possible for various components from the coating formulation to participate in the forming process of charring layers, hence finally influencing morphology of charring layers. In this paper, through effects of different contents of hydrated zinc borate, which was commonly used as flame retardant in polymers, in intumescent fireproof coating on fireproof limit and morphology of charring layers formed for the coating, conclusions were obtained that addition of zinc borate exerted negative effects on the charring layers of intumescent fireproof coating. In addition, by means of tests on different resins used for the coating formulation and based on effects of adding surfactants on charring layers, regularity was obtained for effects of various components on morphology of charring layers. And theoretical analysis of the expansion process of foamed plastics was made to explain the abovementioned phenomena in tests which offered practical guidance in formulation development for intumescent fireproof coating for steel structure.