Preparation Of Water-based Intumescent Flame Retardant Coating Used On Steel Structure

A kind of water-based intumescent flame retardant coating used on steel structure was prepared in this work. It performs well both in fire resistance and water resistance. And most importantly, it is ahalogen-free and environmentally friendly product. The main research work includes three parts.The first part presents the influence of the intumescent system in the performance of flame retardant(thereafter, ―FR‖) coating. To begin with, the orthogonal experiment design and multi-index range analysis were used to define the optimum ratio of two intumescent system: MF-APP: DPER: MEL=28:8:22; MF-APP: PEPA: MEL=21:14:22.Then four kinds of intumescent systems were compared. The results show that the water resistance of different intumescent systems varies widely. The FR coating with APP-200/PER/MEL, APP-1000/PER/MEL and MF-APP/PEPA /MEL released flame retardants after water immersion. As a result, after immersing in water for 48 h, their fire resistance became poor. On the otherhand, the flame retardants of MF-APP/DPER/MELhad low water solubility and a strong combination with the resin, thus the water resistance of its FR coating was superior to the other three intumescent systems. Its flame retardant performance was almost unchanged after water immersion.In the second part, the impacts caused by the resin were studied. Andhow the difference of flame retardant performance was brought by the resin was also studied from the perspective of the softening, melting and thermal decomposition processes of resin itself. The results show that the type of resinhad a significant effect on the flame retardant performance of the FR coating. The order of fire resistance was: acrylic emulsion> vac-veova emulsion> acrylic emulsion> styrene-acrylic emulsion. During the softening and melting process of the FR coating, the melting viscosity of the resin influenced the pore structure of the char by controlling the vibration damping of the bubble. And during the thermal decomposition process, the resin acted as a ―carbon source‖, the efficient of which depended on whether or not the resin and the intumescent system decomposed at the same time. It is concluded that the more the value of the melting viscosity of the resin was, the closer of the decomposition temperature range of the resin and intumescent system was, the better of the char would be generated.The influence of the inorganic fillers, namely, aluminumhydroxide, titanium dioxide,hydrotalcite, montmorillonite, sericite, airgel, expandable graphite, expanded perlite, is presented in the third part. The results show that the char generated by the FR coating containing expanded perlitehad the best resistance of thermal oxidation and flame retardant performance.An optimization formulation of the water-based intumescent flame retardant coating used on steel structure was developed in the end: the ratio of MF-APP: DPER: MEL was 28:8:22, the resin was RS-996 AD silicone-acrylic emulsion, and the pigment/binder ratio was 2.6, 4 wt% of expanded perlite and other additives were added. The testing results show that the coating prepared in this workhad the following advantages: 1. The coating expanded rapidly(fully expanded after around 8 min); 2. The char generatedhadhigh strength(which could withstand 250 g pressure); 3. The charhad a good long-term effect of fire insulation(its fire endurance was more than 1h); 4. The coatinghad good corrosion resistance( its water resistance time was 26 h in the absence of top coating’s protection, and flame retardant performance was almost unchanged after 48h-water immersion); 5. The coating was safe to use and environmentally friendly(because it is water-based). Generally, the performance of it was better than the same type of product in the market.