| In recent years,green new energy vehicles for zero emissions and low pollution have become very popular in China.With the development of technology,components such as batteries and sensors in vehicles are miniaturized and high-frequency.With this comes the problem of heat build-up,which poses a potential hazard to safe driving.Epoxy-cured resins,as excellent insulators,are adhesive and chemically resistant to most substrates and are often used as automotive barrier materials.However,epoxy resins have a low intrinsic thermal conductivity.To improve driving safety,thermally conductive fillers are often added to enhance the material’s thermal conductivity.This thesis aims to prepare non-ionic waterborne epoxy resin thermally conductive insulating coatings by mixing waterborne epoxy resin coatings with boron nitride.Boron nitride（BN）has excellent physicochemical properties,but its interfacial compatibility with the resin substrate is poor and prone to agglomeration.BN needs to be modified to improve the dispersion performance and give full play to the performance of the boron nitride/waterborne epoxy coating.Firstly,this thesis introduced hydrophilic polyether chain segments and polyamines into epoxy resin E-20 through a two-step synthetic reaction to prepare a non-ionic waterborne epoxy curing agent with a self-emulsifying effect.This thesis designed single-factor parallel and multi-factor orthogonal experiments to determine the curing agent preparation process using the epoxy conversion rate as a criterion.The waterborne epoxy emulsion was successfully prepared using the self-made curing agent to emulsify the epoxy resin E-44,with a particle size of 1.8μm.The coating has excellent performance,pencil hardness is 2 H,impact resistance is 50 cm,flexibility is1 mm.Secondly,covalent oxidation is used to hydroxylate the BN surface in strong acid solutions and oxidizing agents,respectively,or attach hydroxide ions to the BN edges in strong alkali solutions,then graft the BN with the modifier so that the BN can be better dispersed in the epoxy resin.The dispersion of the modified BN powder in a mixture of epoxy resin and ethylene glycol butyl ether was observed when the BN was ultrasonically dispersed well.The results showed that the dispersion time of the modified BN was extended,which was prepared by all three modification methods It was finally determined that m BN-570 had the best dispersion effect with a dispersion time of 18 days,which was hydroxylated in a strong alkali solution and then modified by 3%KH-570.Finally,the above m BN-570 was added to the waterborne epoxy coating to prepare the m BN-570/EP composite coating.This thesis immediately explored the effects of different additions of m BN-570 on the thermal conductivity insulation,thermal stability and mechanical properties of the composite coatings.The results show that after adding m BN-570,the thermal conductivity of the coating increased,and the thermal stability improved by 35°C compared to the pure EP coating.m BN-570/EP composite coating maintained the volume and surface resistivity at 1016 orders of magnitude,enhancing the corrosion resistance. |
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