Effect Of The Zinc Borate On The Smoke Properties Regularity Of The Expandable Fire Retardant Coating

Fire retardant coating is a special coating that can delay the combustion of substrate.The water-borne intumescent fire retardant coatings are widely used in wood,textile,metal and other basic materials because of their highly fire resistance.they don't change material performance and easy processing.water swelling fireproof coatings will generate smoke in the early stage,when it in high temperature radiation.In order to study the characteristics of gas particles and smoke generated during the heating process of waterborne intumescent fire retardant coatings.In this paper,we research the effects of different sizes and different adds of zinc borate on the smoke properties regularity of the expansive fire retardant coatings.(1)Analysis of comprehensive ignition time,heat release rate and total heat release rate.It shows that the fire resistance is best when adding a moderate particle size(2-5?m).The size of zinc borate is easy to be agglomerated,and it is not good for mixing and dispersing with other components.The specific surface area of zinc borate decreases when the particle size is too large,and it can not be fully flame retarded with other components.After adding zinc borate,the residual carbon content of the coating increased,and more smoke particles were bound to the expanded carbon layer,which reduced the emission of flue gas.(2)The carbon layer with zinc borate showed an ideal honeycomb structure,the layer of zinc borate sample was more compact and compact by scanning electron microscope.(3)The infrared spectrum response of zinc borate was compared before and after the addition of zinc borate.It was found that the carbon structure changed obviously during the formation of the expanded carbon layer,and the carbon layer of the Zn-P-O complex structure improved the flame retardancy and smoke suppression properties.(4)The results of thermogravimetric analysis show that the thermal decomposition of the coating consists of 4 pyrolytic segments,including the hydrolysis of zinc borate,and the water-borne intumescent coatings after adding zinc borate are superior to the basic coatings without zinc borate in the thermal decomposition temperature,decomposition time and endothermic amount.At the same time,the kinetic equation of the coating layer in the process of thermal decomposition reaction is fitted,and the conclusion is consistent with the test results of the fire and smoke suppression performance.The study on the influence law and mechanism of zinc borate on the smoke suppression of fire retardant coatings is of great significance not only to the decrease of smoke in the early stage of fire,but also the foundation for the development of new low smoke and low toxic fire retardant coatings and new smoke suppressants in the later period.