Study On Preparation And Properties Of Super-thin Intumescent Flame-retardant Coatings For Steel Structures

In this paper,the flame-retardant element bromine of polymeric was achieved using synthesis of low molecular weight high bromic bromine-carbon epoxy resin.The bromine-carbon epoxy resin was applied in flame-retardant coatings.The bromic intrinsical flame-retardant polymers used as binder of fire retardant coatings as well as macromolecule flame-retardant not only improved timeliness of fire retardant,but also reinforced comlatibility of resin and flame-retardant.Tetrabromobisphenol A was prepared using sodium bromide and sodium bromate as brominating agent,under acidic condition and in ethanol solution.Low molecular weight high bromic tetrabromobisphenol A epoxy resin was prepared using tetrabromobisphenol A and epoxy chloropropane under alkaline conditions by stepwise polymerization.Synthesis condition was explored,synthetical temperature was under room temperature and controlled within the range of 25～30℃,sodium bromide was joined in the form of saturation aqueous solution,mol ratio of material BPA:NaBr:NaBrO₃ was 3.0:8.8:4.35,the temperature of refluence reaction was controlled between 70～80℃,and then the influence factor of performance and percentage of production was analyzed.The orthogonal experiments was adopted,designing four factors and three level orthogonal test using reaction temperature,ratio of tetrabromobisphenol A,epoxy chloropropane and dosage of base as main influence factor.When reaction temperature was 60℃,the mol ratio of TBA/ECH was 1/8,TBA/NaOH was 1/3,the epoxy value of synthetical tetrabromobisphenol A epoxy resin was 0.158,epoxy equivalent weight was about 623,average molecular weight was 1266 and degree of polymerization was 2.The functional group of tetrabromobisphenol A and tetrabromobisphenol A epoxy resin has been characterized by Fourier Transform Infrared Ray(FT-IR).When tetrabromobisphenol A epoxy resin was modified by hichloridize polyethylene under room temperature using as binder of super-thin intumescent flame-retardant coatings for steel structure and the ratio of TBA/HCPE was 1/3,the resin content in the film was 1/3,ammonium polyphosphate content between 16%～18%,melamine content between 10%～11.5%,pentaerythritol content between 5%～6.5%,the flame-retardant timeliness of the coatings was 150 min.The best formula of flame-retardant coatings was ascertained using a self-regulating simulative burning tester which tested the performance of fire-retardant for coatings.The mechanism of multi-synergetic fire retardant by system of P-C-N,chloroparaffin,antimonous oxide,zinc borate and molybdic oxide which provided effective academic sustain for research and industrial production that has been studied in-depth by Themrogrvaimertie Analysis(TGA)and Scanning Electron Microscope(SEM).Self-emulsification tetrabromobisphenol A epoxy resin curing-agent was prepared that used for waterborne bromine-carbon epoxy resin.It was found when the ratio of phenyl glycidyl ether and triethylene-tetraamine was 2～2.2:1,the best performance of film achieved.For example surface drying time was 30 min,solid drying time was 15h,alkali resistant time was 360h,resisted impact strength was 45 Kg·cm.The oxygen-index reached 35.4 when using tetrabromobisphenol A epoxy resin as end capping agent.The best formula of waterborne fire-retardant coatings for steel structure was ascertained using orthogonal test which binder,fire-retartant auxiliary and functional additive was analyzed. The performance of waterborne fire-retardant coatings for steel structure reached requirement of national standard.The applied field of bromine-carbon epoxy resin was expanded that amicable environment type coatings and waterborne textile fire-retardant has been prepared.