Preparation Of Waterborne Epoxy Resin Emulsion And Its Anticorrosion Coating

Epoxy resin is widely used in the field of anti-corrosion coatings because of its excellent adhesion,heat resistance,chemical resistance,insulation and mechanical strength.However,traditional epoxy resin coatings are mainly organic solvent systems.During the preparation and use,large amounts of volatile organic compounds(VOCs)are released,which play an important role in the formation of organic secondary aerogels and PM2.5,affecting people’s health.It is an inevitable trend for the development of waterborne epoxy anti-corrosion coatings to use environmentally-friendly water as a dispersion medium.In this dissertation,the method of miniemulsion polymerization was adopted to introduce polyacrylate into epoxy resin system to prepare polyacrylate/epoxy hybrid emulsion.The problem of poor toughness of epoxy resin was solved and based on acrylate monomer.The dissolution and viscosity-reducing effects of epoxy resins improve the synthetic stability of aqueous epoxy resin emulsions.In addition,a non-ionic emulsifier similar to the molecular structure of epoxy resin was synthesized in this thesis,and an epoxy resin emulsion was prepared by reverse conversion method.Its epoxy resin content can reach 100%.The non-ionic emulsifier has good universal applicability to different epoxy resins such as E51,E44 and E20.The prepared epoxy resin emulsion was used as a filming material to study the preparation process of varnish and color paint for waterborne epoxy resin anti-corrosion coating.The toughness,resistance to media and corrosion resistance of the coating were systematically evaluated.The main research content is as follows:1.The epoxy resin and the acrylate monomer are mixed and homogenized,and then the redox initiator is used to initiate the polymerization of the acrylate monomer to finally obtain the polyacrylate/epoxy hybrid emulsion.Through various characterization methods such as infrared,dynamic light scattering,transmission electron microscopy,etc.,the effects of the emulsifying pump operating power and time,the amount of initiator added,the pH value and the emulsifier on the particle size and stability of the emulsion were studied.The results show that after the emulsion polymerization,the polyacrylate and the epoxy resin form spherical particles;different emulsification processes have a great influence on the final emulsion properties.2.Using solid acid as a catalyst,a nonionic epoxy resin emulsifier based on polyethylene glycol,maleic anhydride and epoxy resin was synthesized at a relatively low temperature.Using liquid chromatography,infrared,acid titration and other characterization methods,the influence of reaction time on the reaction degree and the catalytic effect of solid acid were studied.The results show that the solid acid as a catalyst can significantly speed up the reaction;solid acid can effectively control the product structure.3.The above-mentioned self-made non-ionic epoxy resin emulsifier was used as an emulsifier,and a series of non-ionic emulsifier-based waterborne high-solid epoxy emulsions were obtained by emulsifying the bisphenol A type epoxy resin in an inverse conversion method.The effects of the structure and amount of non-ionic epoxy resin emulsifier,the content of solvent and the content of anionic emulsifier on the particle size and stability of the emulsion were studied by means of dynamic light scattering.The results showed that when the addition amount was controlled at 5%,an emulsion with stable particle size of 400-500 nm was obtained.4.Using the above-mentioned aqueous high-solid epoxy emulsion as a matrix resin,an anticorrosive varnish coating and a corrosion-resistant color paint coating are prepared.After adding the curing agent,a corresponding anti-corrosion coating is obtained after curing.The media resistance,salt spray resistance and physical and mechanical properties of varnish coatings and pigmented coatings were studied;the influence of the pigment-to-salt ratio on the salt spray resistance of pigmented coatings was studied;the varnish was characterized by Electrochemical Impedance Spectroscopy(EIS).Corrosion resistance of coatings and pigmented coatings.The results show that the coating prepared with the above aqueous high-solid epoxy emulsion plus curing agent has excellent adhesion,bending resistance,impact resistance and pencil hardness.The paint coating is resistant to salt spray for more than 800 hours and water resistance for more than 2000 hours;the varnish coating is resistant to salt spray for more than 2,000 hours.And with the increase of the pigment ratio,the salt spray resistance of the colored paint coating is significantly improved.