Synthesis And Application Of Water-based Epoxy Curing Agent

Air filter paper is one of the key materials to make air cleaner of automobile engines, thisfilter paper must have high hardness, deflection and gas permeability. With high adhesion,great corrosion resistance, epoxy coating has been used widely in heavy-duty coatings all overthe world. With the improvement of environmental protection awareness, coating has becomethe hot topics; so, more and more researchers focus on water-based epoxy resin andwater-born epoxy curing agent.In this experiment, aromatic amine A was modified by novolac epoxy resin with iongroup to obtain the water-borne curing agent, which has good compatibility with water-basedepoxy resin. Modified aromatic amine curing agent can be neutralized by acetic acid anddispersed into water by force. The effect of the type of modified amines and the solvents onthe performance of curing agent was studied, the optimized synthesis process is asfollowing:firstly,30%epoxy ring of novolac epoxy resin was opened at80℃,2h. Secondly,aromatic amine A was modified by above modified novolac epoxy resin at80℃,2h, and themolar ratio of aromatic amine A/epoxy=1.2:1. Finally, the stable epoxy curing agent emulsionthat the average particle size is100nm can be obtained with stirring speed at2000rpm.Thestructural characteristics of this synthetic product structures was examined by FTIR spectrum.The effect of the amount of addition water on particle size, conductivity, and viscosity ofthe curing agent emulsion was investigated. The result shows that the particle size of theemulsion become smaller quickly with the increase in the amount of addition water, theminimum particle size of emulsion is about100nm when the weight of water is equal to thesystem of curing agent. With the increase in the amount of addition water, the viscosity ofemulsions become smaller firstly and then increases, when reaches the inversion point, it willdecreases rapidly. The conductivity of the emulsion first increases and then decreases.The effect of the proportions of water-based epoxy curing agent/water-based epoxy resinwas studied. The apparent activation energy and the reaction order were calculated byKissinger equation and Crane equation. The results show that when the mass ratio ofwaterborne epoxy resin and water-based epoxy curing agent is3:1, the curing system will release the largest heat and the activation energy Ea=39.82KJ/mol, reaction order is0.85.From the analysis of curing kinetics and the method of T-β, the best initial curingtemperature, peak temperature and the end temperature are33.95℃,79.65℃and123.45℃and the recommend curing process is80℃/2h+120℃/2h.The effect of this epoxy resin emulsion system on performance of filter paper wasdiscussed. The results show that the longitudinal quite degrees of the filter paper with thisemulsion will be improved from15KN/m to75KN/m, busting will be improved from55KPato250KPa, while its permeability will be decreased from380mm/s to335mm/s. It indicatedthat this emulsion could improve the performance of filter paper obviously and realize ourprevious achievement.