| The coating material is the most widely used,the most economical and practical anti-corrosion method.The presence of the polar groups such as the oxygen group and the hydroxyl group in the epoxy resin has good adhesion to the metal substrate.The epoxy resin has excellent corrosion resistance because of its low polarity,stable C-C bond and ether bond.In order to meet the requirements of environmental protection,the development of waterborne epoxy anticorrosive coatings was developed,but it also has the disadvantages of high density,low impact toughness,brittleness,easy cracking and so on.The researchers found that polyaniline anticorrosive coating has a unique anti-corrosion mechanism,excellent corrosion resistance.However,the polyaniline has a low adhesion,and the polyaniline is difficult to dissolve,which has a great limit to its application.Polyaniline suspension was prepared by microemulsion method in this paper.The polyaniline suspension prepared by this method has a certain stability,and it is not necessary to carry out the post treatment process,which can be directly mixed with the aqueous epoxy emulsion as the base material of the anticorrosive coating.It is found that the corrosion resistance of polyaniline is related to its electrical conductivity.The higher the electrical conductivity,the better the corrosion resistance.In this paper,we first use the method of micro emulsion polymerization,using organic inorganic mixed acid to synthesize polyaniline suspension.The effects of different formulations and processes on the conductivity of polyaniline were studied,a high conductivity of polyaniline was prepared,and the structure was characterized by IR,XRD.The results showed that the optimal condition was:nDBSA:nHCl=3:2?n?:n??=2:1?n???:n??=1:1??mOP-10:mAn=2:3,and the reaction temperature is 30??the reaction time is 9 h.In this case,the property of the prepared product was best.The polyaniline suspensions were mixed with waterborne epoxy emulsion directly,and make it into a film.It was found that the corrosion resistance of modified waterborne epoxy emulsion was greatly improved,and by comparing the results of scratch test,it is found that the modified coating has excellent scratch resistance and pitting corrosion resistance.Anticorrosion painting is prepared withthe modified emulsion as binder,titanium dioxide,glass flake,talcum powder,barium sulfate,mica powder as fillers and pigments,and adding proper additives.A single factor experiment was used to study the main factors affecting the performance of the coating,and then the orthogonal optimization was carried out according to the results of the experiment,and the optimum formula was obtained.The results show that the coating of the optimal formula as follows: the glass flake is 80 mesh and the amount is 35%,The ratio of polyaniline suspension to epoxy emulsion is 3:3,pigment binder ratio is 1.25,curing agent is 6.7%,brushing two times.The prepared anticorrosive coating has good corrosion resistance.Comprehensive test results show that the physical and chemical indicators of the coating to meet the requirements of JG/T224-2007.The development of waterborne epoxy anticorrosive coatings with low VOC content,safety and environmental protection,excellent corrosion resistance,to meet the requirements of building steel structure for anti-corrosion coatings. |
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