| It is important to use epoxy intumescent fire-retardant coating for building structure and petrochemical facilities to slow the collapse of the steel structure,delay the spread of fire and protect safety,maintain the steel structure.But ammonium polyphosphate(APP)has a bad effect on the use of the coating due to its water absorption.Therefore,the application of microcapsule on the APP can effectively solve the problem of the moisture absorption when the APP is in use.There're a lot of domestic reports about the polyurea microcapsules could solve moisture absorption and weather resistance because polyurea has good water resistance and weatherability,but there has not been studied about the polyurea microcapsule which coated APP.The isocyanate and APP dissolved in toluene and deionized water,respectively,and the polyurea microcapsule of APP was compounded by under a certain temperature and catalyst by interfacial polymerization.Using the method of single factor investigation to make sure that the polymerization reaction temperature is 50?,the reaction speed is 1500r/min,the catalyst amount is 3g,deionized water with APP to use is 4:1,the amount of IPDI is 25g.TG results prove polyurea microcapsules will not affect the thermal decomposition of the APP.The fire-retardant coating was prepared with epoxy resin as film forming resin,polyurea microcapsules,dipentaerythritol and melamine as fire retardant system,sepiolite,expanded perlite,hollow glass microsphere,titanium dioxide,aluminum hydroxide,magnesium hydroxide as fillers,and added with additives and thinners to prepare coatings.Experimental results prove that the coatings contained microcapsules had better mechanical strength(hardness of 2H,impact resistant up to 50cm·kg,adhesion performance achieve grade 1,flexible performance achieve 0mm),the lowest bibulous rate is 0.54%,and weather resistance is the longest time of 16d,the impedance value of 2.6·10~6?.When the microcapsules were added in,the ignition time was increase while quality loss,peak heat release rate and total heat were decrease,and the back temperature of base material was decrease 60?.Finally,the coating which included 55g of epoxy,45g of flame-retardant system,and 15.5g of fillers and cosolvent were selected as the best formulation system. |
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