A hybrid intumescent fire retardant coating from cake- and eggshell-type IFRC

In this study the applicability of flame retardant mixed with a carbon source (such as pentaerythritol) for the intumescent fire retardant coating (IFRC) daubed on the top of a piece of plywood was investigated. There are three kinds of flame retardants used in this study: (1) artificial mesophase graphite powder (MGP), (2) sericite (Al4(OH)4(KAlSi3O10)2), and (3) graphite. The desirable sizes of graphite, MGP and sericite were obtained by sieving. The graphite, MGP and sericite were characterized using a scanning electron microscope (SEM) and an energy dispersive spectrum (EDS). The IFRC, which consisted of 19.8% of flame retardant (or flame retardant mixed with carbon source), 15% of dehydrate agent, 18% of foaming agent, 7.2% of resin binder, and 40% of solvent, was prepared and daubed on the top of plywood. The fire protection capability of IFRC was tested using a flammability 45° tester. A conventional IFRC (with the carbon source) was also prepared to study the effect of adding the mixture of flame retardant and carbon source on the fire protection capability of IFRC. The microstructures of the conventional IFRC, the IFRC with flame retardant, and the hybrid IFRC (with flame retardant and carbon source) were inferred and demonstrated using SEM micrographs of the cross-section of three kinds of burnt IFRC. Most interestingly, the fire protection capability of the hybrid IFRC exceeds that of the conventional IFRC even though the percentage of carbon in the burnt hybrid IFRC is less than that in the burnt conventional IFRC.