| Under sunlight,excessive temperature often leads to evaporation loss of aviation fuel in the large outdoor storage tanks.At the same time,the safe operation standards of civil aviation also puts forward higher fire-retardant and flame-retardant requirements for structural materials used in the storage area of aviation fuels.In view of this situation,the development of coating system with good thermal insulation and flame retardancy for the outer protection of the tank equipment not only helps to reduce the evaporation loss of aviation fuels,but also can improve the fire resistance limit of the tank structure which will be further improve the fire safety of aviation fuel storage.This coating system also has a broad application prospect in large-scale buildings,pipes,bridges and other related fields.The traditional outer protection coating system for the storage tanks of aviation fuels belongs to a three-layer coating system formed by acrylic polyurethane topcoat,epoxy intermediate paint with micaceous iron oxide pigment and epoxy zinc rich primer.Based on this traditional coating system,a new kind of coating system have been prepared by adding thermal insulating agent to acrylic polyurethane top paint and flame retardant to epoxy intermediate paint with micaceous iron oxide pigment respectively according to the material design principle of thermal insulation and flame retardancy.The preparation of paraffin-based microcapsules as the phase change material(PCM),the modification treatment of magnesium hydroxide flame retardant particles,and the effects of heat insulating agent and flame retardant additives on the basic properties of coatings,the thermal insulation and flame retardant application of the coating system have been systematically studied.The results showed that the paraffin-based PCM microcapsules were prepared by an in-situ polymerization method with the mixture of pentadecane,octadecane and lignocerane in a mass ratio of 1:1:1 as the core material and urea-formaldehyde resin as the wall material.It was found that the prepared paraffin-based PCM microcapsules have good shape,particle size distribution and thermal storage performance when the stirring speed is 600 r/min,the dosage of core material is 20 g,the mass ratio of core to wall is 1.27 and the pH value of reaction system is 2.0.The surface treatment of magnesium hydroxide particles was carried out in a sodium oleate wet process.By means of infrared spectrum,scanning electron microscope and thermal analysis,it was found that the hydrophobicity of magnesium hydroxide was increased and the decomposition temperature was broadened after the treatment.The dispersion of epoxy resin was also improved.By means of infrared spectroscopy,scanning electron microscopy and thermal analysis,it was found that the hydrophobicity of magnesium hydroxide increased and the decomposition temperature widened after surface treatment.The dispersion of magnesium hydroxide particles in epoxy resin system was improved as well.Under the experimental conditions,when the amount of paraffin-based PCM microcapsules heat insulating agent in acrylic polyurethane coating is 4 wt.%,the basic properties of the modified coating material are excellent.At the same time,the heat insulation time reaches about 22 min,which shows that the heat insulation effect of the coating layer is pretty good.When the amount of magnesium hydroxide particles with surface treatment is 6 wt.%,the basic properties of the modified epoxy intermediate paint with micaceous iron oxide pigment can meet the requirements of relevant technical specifications.The flame retardant time of the modified coating can reach 281 s,which means the flame retardant effect of the epoxy intermediate paint with micaceous iron oxide pigment was greatly increased.Through the composition optimization of modified acrylic polyurethane coating and modified epoxy intermediate paint with micaceous iron oxide pigment,the prepared multiple coating system achieved favorable heat insulation and flame retardant effect. |
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