Preparation Of Waterborne Epoxy Heavy Anticorrosive Coatings

The anticorrosive effect of heavy-duty anticorrosive coatings in marine engineering,chemical industry,shipping and other fields cannot be replaced,so the research and development of heavy-duty anticorrosive coatings is very necessary.In the system of heavy-duty anticorrosive coatings,film-forming substances and rust-proof pigments play a decisive role in the anticorrosive performance of heavy-duty anticorrosive coatings.Epoxy resin is widely used in heavy-duty anticorrosive coatings because of its excellent anticorrosive performance.At present,solvent-based epoxy heavy-duty anticorrosive coatings are the main type in the market,which causes serious environmental pollution.Graphene oxide is used in anticorrosive coatings because of its excellent barrier performance,but it is easy to agglomerate,so it is difficult to achieve the best effect.In view of the above situation,a non-ionic epoxy self-emulsifying curing agent was synthesized to prepare water-borne epoxy coatings,then graphene oxide was modified by p-phenylenediamine and water-borne epoxy graphene oxide anti-corrosion coatings were prepared.The effect of graphene oxide content on the related properties of coatings was studied.Finally,zinc powder,modified graphene oxide and self-emulsifying were used.Waterborne epoxy heavy-duty anticorrosive coatings were prepared with curing agent,epoxy resin and related additives.The effects of zinc powder and modified graphene oxide on the properties of the coatings were studied.The main contents and conclusions were as follows:(1)The results show that when the mass ratio of diethylenetriamine:formaldehyde:bisphenol A:polyethylene glycol diglycidyl ether:O-cresyl glycidyl ether is 2:1:1:1:0.8,best effect of the non-ionic epoxy self-emulsifying curing agent is obtained.The particle size of the emulsion is 289 nm,the surface dry time of the coating is 3 h,the adhesion force is 0 grade,the hardness can reach 3 H,and the dielectric resistance is good(water resistance reaches 20 days,acid resistance 2 days,and salt tolerance reaches 14 days.(2)Graphene oxide was modified by p-phenylenediamine,and the hydrophilic groups of graphene oxide were reduced by sedimentation test.FTIR and XRD measurements showed that the reaction between p-phenylenediamine and epoxy and carboxyl groups on graphene oxide resulted in a larger interlayer spacing.SEM morphology analysis showed that the modified graphene oxide was uniformly dispersed and non-agglomerated in the epoxy coating.The results show that when 0.5%modified graphene oxide is added,the waterborne epoxy graphene oxide coating has the best comprehensive performance,with a hardness of 5H,adhesion of Grade 1,flexibility of1 mm,salt resistance of 30 days,acid resistance of 6 days,and impedance of 45 days at low frequency of 6.94X10~6?.cm~2.(3)Waterborne epoxy heavy-duty anticorrosive coatings were prepared with zinc powder,modified graphene oxide,self-emulsifying curing agent,epoxy resin and related additives.The results of open-circuit potential analysis show that the cathodic protection time of the coating increases first and then decreases with the increase of the content of modified graphene oxide when the content of zinc powder is 50%,and the protection time of the coating with 50%Zn/0.5%FGO is the longest.The results of medium resistance and neutral salt spray test show that the coating with 50%Zn/0.5%FGO has the best performance.The neutral salt spray resistance of the coating is only slightly discolored for 1200 h and reaches 75 days.The EIS test results show that the coating with 50%Zn/0.5%FGO has the best anticorrosive performance.After 60 days,the low frequency impedance of the coating is 3.84x10~6?.cm~2.