| Water-based epoxy resin coating has become one of the most important water-based heavy anticorrosive coatings due to its excellent mechanical properties,high crosslinking density and adhesion strength.Graphene,with its unique two-dimensional nanostructure and excellent barrier to water molecules,oxygen and electrolytes,serves as a metal anticorrosive coating with excellent shielding performance to improve its anticorrosive performance.Polyaniline coating can prevent corrosion by inhibiting the penetration of corrosive medium and forming passivated oxide layer on metal surface.At present,researches on the dispersion stability of graphene composite anticorrosive coatings and the laminar relations of polyaniline composite anticorrosive coatings are the problems that need to be solved.Based on the above problems,this paper synthesized non-ionic emulsifying epoxy resin curing agent and prepared water-based epoxy anticorrosive coating.By combining with functionalized graphene derivatives and self-doped polyaniline,different types of water-based epoxy resin anticorrosive coating were obtained,and the structure and anticorrosive mechanism were studied.Specific contents and results are as follows:?1?Through the polymer molecular structure design,with bisphenol A type epoxy resin,triethylene tetramine?TETA?,trimethylolpropane three glycidyl ether epoxy groups?TPEG?and methyl polyoxyethylene ether?MEH?as raw materials,synthesis of A series of nonionic waterborne epoxy resin emulsion type curing agent?WPEA?,and curing agent is obtained by phase inversion method-epoxy resin composite emulsion?WPEA-EP?,and as the base resin used in metal corrosion coating.It is found that suitable polyether chain structure can significantly improve the emulsifying and dispersing performance of curing agent to epoxy resin,and its non-ionic property can solve the "acid corrosion" problem of traditional acid neutralizing cationic epoxy curing agent on metal surface.At the same time,the rigidity of curing agent,compatibility with emulsified epoxy resin,emulsifying dispersibility and hydrophilic and hydrophobic properties of epoxy resin with different epoxy values were all changed to different degrees.In the synthesis formula of this paper,when the MEH content is 0.03mol and the epoxy value introduced is 0.35mol/100g,the curing agent obtained has the best comprehensive performance,the coating resistance is greatly improved,and the salt spray test proves that its corrosion resistance is higher than other ratios.Non-ion emulsion type molecular structure of the preparation of waterborne epoxy resin curing agent strategy and design scheme is applicable to the general design of waterborne epoxy resin emulsion,not only solved the organic acid and cationic curing agent of"pickling" problem,also for the development of the design of the new type of epoxy coating and floor coating provides a theoretical and technical support.?2?Thionyl chloride and go were used to form acyl chloride groups through acl chlorination reaction,and then polyamino functional go?MAGO?was obtained by reaction with 2-amino-4,6-dichlorophenol,and then water-based MAGO/epoxy nanocomposite coating?MAGO/EP?was obtained by composite with water-based epoxy resin.The MAGO prepared was covalent bonded to the epoxy resin by the formation of amide bond and primary amine group.It is found that the combination of covalent bonds is beneficial to improve the cross-linking density and barrier properties of the nanocomposite coating,and to improve the separation phenomenon caused by the re-aggregation of the nanocomposite materials and polymers.At the same time,its polyamine structure can improve the water dispersibility of graphene nanomaterials,enabling the composite coating to establish a balance among dispersion stability,mechanical properties,water resistance and long term anticorrosion mechanism.It was found that the water resistance of MAGO/EP,small molecule shielding property and adhesion strength were much higher than GO/EP composite coating.After 40 days of simulated corrosion,the impedance modulus of MAGO/EP was three orders of magnitude higher than that of GO/EP,and the corrosion resistance life was extended by several times.The water-based graphene/epoxy composite anticorrosive coating constructed in this study is a new green anticorrosive coating with high performance and provides a new idea for molecular design of self-crosslinked graphene anticorrosive coating,which has strong theoretical significance.?3?The preparation for aluminum tripolyphosphate/graphene oxide water composite corrosion slurry?AlTP/GO?through the ball mill dispersing process,and applied to the waterborne epoxy coatings was prepared aluminum tripolyphosphate,waterborne epoxy composite coating/graphene oxide?EP-AlTP/GO?,studied the AlTP/GO on the dispersion of waterborne epoxy resin,corrosion mechanism and anti-corrosion performance.The results showed that the introduction of go improved the water resistance and shielding properties of the coating.Aluminum triphosphate can improve the adhesion strength of coating on metal substrate.By electrochemical test?Bode?and environmental scanning electron microscopy?SEM?test?E-SEM?test,found that AlTP/GO can effectively enhance the water-based epoxy coating for the shielding effect of corrosion medium,limit the spread of the corrosion reaction,soaking in 3.5%NaCl aqueous solution at 40 days after the low frequency impedance of 7.02 ×107? cm2,salt spray test 400 h after the metal surface smooth,metal corrosion is not obvious diffusion,EP-AlTP/GO artificial lesions surrounding oxygen levels as low as 15.66%,restrain the formation of iron oxide.?4?In this chapter,carboxylated polyaniline?CPANi?and sulfonated polyaniline?SPANi?were prepared by free radical polymerization with p-aminobenzoic acid and p-aminobenzonic acid as modifiers respectively.The structure of polyaniline nanomaterials doped by two doping methods and their effects on the corrosion resistance of waterborne epoxy resin were compared.The research shows that:?1?after doping polyaniline water dispersion stability can be improved,as an anticorrosive pigment applied to EP coating,filled with EP coating there are microscopic pores and cracks,coating shielding corrosion medium ability improved.?2?the addition of polyaniline can promote the metal coating/metal interface to form a layer of dense oxidation film,play the role of secondary shielding.?3?since the electroactive polyaniline doped fiber structure,its means of bypass dispersion is advantageous to the composite material to form conductive path,dispersivity of the nanometer materials,conductive composite materials were determined,the higher the conductivity,penetrate the lower threshold,Fe in the anodic reactions of corrosion were produced by the oxidation of Fe2+electronic conductive pathways through more easily transferred to external coating of oxygen,therefore,pathway is essential for the electronic transfer.According to the test results,SPANi/EP has a higher conductivity,which is conducive to the migration of electrons generated by corrosion reaction,revealing the nature of the difference in corrosion resistance of polyaniline composite coating doped with different structures. |
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