| With the development of society and the advancement of science and technology rapidly,the production of high-performance environmentally and pollution-free fireproof coatings can not only reduce casualties,reduce economic losses,but also contribute to the progress of human civilization.The fire-retardant coating is applied to the surface of the object.In the event of fire,the coating films is flame-retardant or non-fired,which has a good protection effect on the substrate and wins time for fire extinguishing and personnel evacuation.At present,the research is limited to study on inorganic and organic components of the fire-retardant coatings.In this paper,we aimed to prepare a thick-thin composite fire-retardant coating.It can improve the economic benefits and environmental problems,and reduce personal injury caused by the release of toxic gases from intumescent fire-retardant coatings.Moreover,the fire resistance limit is improved.Firstly,through the physical and chemical analysis of the experimental raw materials to know,we used Portland cement,refractory clay and high alumina cement as inorganic binders,and expanded vermiculite,perlite,sepiolite and ceramic fibers as inorganic filler aggregates to prepare thick type fire-retardant coating.After TGA-DSC,XRD,SEM and other analytical tests,the mechanism of thick fire-retardant coatings was divided into four parts:coating drying and endothermic stage;partial material dehydration and gas volatilization endothermic stage;pyrolysis carbonization exotherm;the remainder continues to carbonize.After a series of trials and screenings by orthogonal experiments,a relatively reliable combination ratio was obtained.It was discussed that the effects of particle size,content of expanded vermiculite and expanded perlite content on the dry density and thermal conductivity.The sample prepared from the optimum formulation had a dry density of 0.50 g/cm3 and a thermal conductivity of 0.157 W/mk.Secondly,we studied that the effects of pure acrylic emulsion,styrene-acrylic emulsion and acrylic emulsion on the fire performance of fire-retardant coatings.From the results of fire test,the acrylic emulsion was selected as the film-forming substance by its better thermal stability and better adhesion.The results of L9?34?orthogonal experiment on the intumescent flame retardant system showed that the optimal ratio was m?APP?:m?MEL?:m?PER?:m?Mg?OH?2?=28:15:8:3.And the reaction mechanism of the intumescent flame-retardant was studied by TGA-DSC comprehensive thermal analysis.Then,the inorganic filler sepiolite was modified by silane coupling agent KH-570,and it was determined the optimum mass ratio was KH-570:sepiolite=0.04:1 by XRD,FTIR and SEM analysis.The fire test results showed that the sample had the best physical and chemical properties such as heat insulation and water resistance when modified sepiolite content 3%.and the TG results showed that the residual amount of the sample was 34.68%,which improved the oxidation resistance and strength of the carbonized layer.Finally,the composite fireproof coating was prepared by two different types of fireproof coatings.Through the tensile test,it was analyzed that the influence of the curing life of the thickest fireproof coating as the bottom layer and the curing temperature and curing humidity on the bond strength of the composite layers.The results showed that the adhesion was enhanced with the increase of the bottom layer's curing days.In addition,the curing temperature and the curing humidity had a great influence on the adhesion.If the humidity and the temperature were too high or too low,which would lead to decrease the adhesion of composite layers.The optimum process of this experiment was to maintain the curing humidity of 70%,the curing temperature of 25?,and then the primer coating cured for 7days.Then to coat the thin fire retardant coating,the prepared composite fire retardant coating had the strongest adhesion between the composite layers,the strength value was 0.340 MPa. |
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