| Compared with thick coating and thin coating, ultrathin steel structure fireproof coating is finer and thinner, simpler and more convenient with better decorative properties. Ultrathin fireproof coating is popular in the field of fireproof coating.The effects of synthesis conditions, the amount of initiator, formulation and the reaction time of acrylic resin on the performance of fireproof coating were discussed. The influences of the binder with acrylic resin and epoxy resin on the performance of the coating and expandable graphite(EG), ammonium molybdate(AM), nano-Mg(OH)2, EG/AM, EG/nano-Mg(OH)2 on the fireproof performance of the coatings were also investigated. The fireproof limit was measured by vertical burning method. The thermal stability of coating was investigated by thermogravimetry(TGA). The thermodynamic model of coating was established and the activation energy was calculated.The results showed that the optimum condition for synthesis of acrylic resin is that the amount of initiator is 1.3g ,solvent is 65g , butyl acrylate is 30g and the time of drop monomer is 120min. The mechanical performance of coating can be enhanced by the resin complex. The fireproof time prolongs 3.8min, when the proportion is 2:3.The fireproof performance of the coating can be enhanced by EG, AM, nano-Mg(OH)2 and their synergistic effect. Based on the study of single factor by the orthogonal experiments: the thermoplastic acrylic resin is 3.0, MPP is 1.0g, MEL is 3.0g, PER is 1.0g, EG is 0.5g, AM is 0.65g and nano-Mg(OH)2 is 0.14g. The fireproof limit is146min when film thickness is 1.80mm. The physical and chemical performance accords with the《Fire resistive coating for steel structure》(GB14907-2002).The study of dymamics showed that the EG/AM activation energy is higher than those of AM, EG and EG/nano-Mg(OH)2 coating during 200℃~330℃and 330℃~500℃., the fireproof performance of EG/AM is the best. The reaction activity of EG/AM is the lowest. The same as the results of vertical burning.
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