| Metal corrosion affects all walks of life in human society.In the corrosion resistant coating system,epoxy resin has been widely used because of its excellent mechanical properties and chemical stability.Traditional solvent-base anticorrosive coatings do serious harm to natural environment and human health,so water-based anticorrosive coatings come into being.But compared with solvent-base coatings,the corrosion resistance of waterborne coatings still has a certain gap.It is of great significance to study the green,environment-friendly and excellent anticorrosive waterborne epoxy anticorrosive coatings for the development of society.The main research contents of this paper are as follows:1.Optimization of the basic formula of waterborne epoxy anticorrosive coating.Based on the experiments and market research,the effects of certain additive types and amounts on coating properties are analyzed,and the basic formula is finally determined.The experimental results show that the water-based epoxy emulsion DY-601 and waterbased curing agent DY-175 are selected as film forming materials.2093 transparent epoxy defoamer is selected as the defoamer,the dosage is 0.5 wt%;DY-330 is selected as anti-flash rust agent,the dosage is 0.5 wt%;Dispersant SRE-4190 is selected as dispersant,and its dosage is determined to account for 0.3 wt% of the total amount.Tego 270 and 450 are used as the wetting agent of base material and leveling agent,respectively,with the dosage of 0.1 wt%.The pigment fillers are included of rutile titanium dioxide about 5 wt% and mica powder 2.5 wt%.2.Taking zinc phosphate and aluminum tripolyphosphate as anticorrosive pigments,the influence of types and contents of them on the performance of waterborne epoxy anticorrosion coating are analyzed and discussed.The viscosity,drying time,adhesion and hardness properties of different corrosion resistant coatings are investigated.The corrosion processes and corrosion degree of different corrosion resistant coatings in 3.5% NaCl are studied by electron photograph,SEM,electrochemical impedance spectroscopy and polarization curve.The experimental results show that the drying time of the coating is prolonged and the adhesion and hardness of the coating are improved after adding the anticorrosive pigment.When the coating is added with 5 wt% zinc phosphate or 7 wt% aluminum tripolyphosphate,the adhesion is 0 grade,the hardness is 6 H,and there was no obvious change on the surface after soaking in 3.5% NaCl for 30 days.The electrochemical test results show that 5wt% zinc phosphate coating possess better corrosion resistance.3.Cationic waterborne epoxy emulsion and anionic waterborne epoxy emulsion are prepared by chemical modification method.The surface functional groups of anionic and cationic emulsion are characterized by infrared spectroscopy.The stability of the two kinds of homemade emulsion and the basic properties of the corresponding coatings are studied and discussed.The experimental results show that the two emulsions possess good stability after dispersing in water.The maximum water content of the cationic emulsion is about 40%,and that of the anionic emulsion is about 20%.The surface drying time of cationic emulsion is 6 h,hard drying time is 24 hours;The epoxy value is about 0.329 mol/100 g,and the solid content of emulsion is 97%.Adhesion level is 0 grade;The hardness is H.The surface drying time of anionic emulsion is 3 h.The hard drying time is 18 h;The epoxy value is about 0.129 mol/100 g.The solid content of emulsion is 50%;Adhesion level is 0 grade;Hardness is 4 H.The corrosion resistance of self-made anion emulsion and cationic emulsion varnishes is improved compared with that of commercially available varnishes.The adhesion and hardness of the anionic water-based epoxy emulsion coatings are all 0 and 4H,and the anionic emulsion coatings have no change after soaking for 14.The electrochemical test results show that the coating made of anionic waterborne epoxy emulsion has good corrosion resistance.This work provides reference and data support for the preparation technology and application field of waterborne epoxy emulsion. |
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