Preparation And Performance Study Of Waterborne Intumescent Flame Retardant Coatings For Steel Structure

Solventborne ultra-thin flame retardant coatings for steel structure has been limited owing to its high content of volatile organic compounds（VOC）. In reserve, waterborne ultra-thin flame retardant coatings for steel structures with polymer lates as binder have become the emphasis of modern research works, as it cuts down the emissions of VOC,reduces the health hazards and environmental pollution, being in accordance with the trend of energy conservation and environmental protection.In this paper, we determined the basic formula of flame retardant coating whose basic material is water epoxy system and the optimal proportion of intumescent flame retardant componets, and investigated the effect of inorganic fillers, new triazine charring agent and ammonium polyphosphate nanocomposites by water reisting test, fire protection test, Cone,TG, SEM, TG, XRF and XPS analysis. We offterd basis data for preparaing intumescent flame retardant coatings which had excellent fire proof property, low release of smoke and heat and good application performance. The main research work are as follows:（1） The effects of binder on the fire retardant performance of flame retardant coatings were intesnsively studied in terms of physical and chemical properties, fire resistance and intumescent char layer. The results showed that: the epoxy curing system EP-2/HB with aromatic amine curing agent had better sealing ability, it can make the coatings have good adhesion, compact strength and water resistance when it was used as the binder of the coating.（2） When epoxy system EP-2/HB was used as the binder and ammonium polyphosphate/dipentaerythritol/melamine（APP/DPER/MEL） were used as the intumescent flame retardant（IFR） system, the effects of the proportion of IFR were studied by orthogonal experiment. In addition, the comparison of new intumescent flame retardant coating（EP/N-IFR） with triazine charring agent and traditional intumescent flame retardant coating（EP/T-IFR） were investigated. The results showed that: the optimal proportion of intumescent flame system was APP:DPER:MEL=37:15:13. The effect order of components on fire retardant coating was MEL>IFR>APP:DPER. The triazine charring agent can enhance the heat insulation effect and reduce the heat and smoke release of the coating.（3） The effect of the inorganic fillers of magnesium hydroxide, zinc borate and nanometer titanium dioxide on the fire resistance of the coatings was investigated.Magnesium hydroxide and zinc borate can enhacen the fire proof performance of the coatings in different extent separately, when both of them were applied into the coatings,the fire resistance and flame retardancy can be further improved.（4） The effect of ammonium polyphosphate montmorillonite nanocomposite（APP-MMT） and ammonium polyphosphate nano titanium dioxide nanocomposite（APP-TiO₂） and the flame retardant mechanism were investigated. Thermogravimetric difference analysis showed that MMT can react with APP in high temperature to produce the product with high stability so as to enhance the flame retardancy. XRD and thermogravimetric difference analysis revealed that nano titanium dioxide in APP-TiO₂ can react with the decomposition product of APP to produce titanium pyrophosphate. The titanium pyrophosphate with high thermo stability can prevent the oxidation decomposition of the char layer and generate more stable carbon residue.