Study On Preparation Of Graphene Modified High-solid Waterborne Hydroxy Acrylate And Its Anticorrosive Coating Performance

The annual economic loss caused by metal corrosion is huge and even more than the sum of the losses caused by fire,wind and earthquake.It is well known that the most effective and convenient way to prevent metal from corrosion is to use coating protection.Owing to the low degree of water-based anti-corrosion coatings,about 3 million tons of VOC are discharged into the environment every year,causing air pollution and haze to aggravate,so it is imperative to improve the degree of water-based anti-corrosion coatings.However,the water-based anticorrosive coating prepared through the emulsion polymerization has a large molecular weight of the film-forming substance and a small amount of cross-linking monomer introduced,which resulting in the much poorer anticorrosive ability of the paint film and far lower than that of the traditional solvent-based anticorrosive coating.In order to utilize effectively the unique advantages of acrylate copolymers,this article adopts solution polymerization and then redispersion to prepare hydroxy acrylic resin dispersions with excellent anticorrosive properties.By improving the solid content of the solution polymerization process,reducing the solvent content,and reducing VOC emissions,a new type of highly cross-linked water-based acrylic resin is prepared.In order to further improve the anti-corrosion performance of the coating,graphene with super-hydrophobicity,super-isolation and super-high specific surface area were introduced into the polymerization system to study its effect on polymerization stability,storage stability and anti-corrosion performance.First,use solution polymerization to prepare high-solid hydroxy acrylic resin with a solid content of 80%,then neutralize with amine,and finally emulsify and disperse with water to obtain resin dispersion.By adjusting the synthesis process,the amount of initiator,solvent ratio,functional monomer and neutralization degree,the molecular weight,crosslinking degree and neutralization degree of the hydroxy acrylic resin,the hydrophilicity and hydrophobicity of the polymer chain and the solvent is changed.Finally,xylene(XYL)and propylene glycol monobutyl ether(PNB)are used as solvents,and the solvent ratio is XYL:PNB=1:1.The amount of initiator TBPB is 3.0 wt%,the degree of neutralization is 100%,the polymerization stirring speed is 300 rpm,and the neutralization dispersion speed is 3500 rpm,under the condition of stepwise feeding.Successfully prepared the high-solid hydroxy acrylic resin dispersion with a viscosity of 800 mPa·s and a particle size of about 140 nm.Using RGO to modify the hydroxy acrylic resin in situ to improve the anti-corrosion performance of the coating,but RGO will capture free radicals,which reduce the monomer conversion rate.Improve the monomer conversion rate by increasing the polymerization temperature and prolonging the polymerization time.When the polymerization temperature is 130? and the amount of RGO is 2.5 wt%o,the polymerization time is extended to 8 h,and the conversion rate can reach 99%.When the amount of RGO is 2.5 wt‰ and the polymerization time is 6 h,the temperature can be increased to 150?,and the conversion rate can also be increased to 99%.The amount of HEMA not only affects the physical properties of the coating,but also influences the anti-corrosion performance of the coating.When the dosage of HEMA is 11wt%,the anti-corrosion performance is the best,and the |Z|0.01 is 1.10×104?·cm2.The addition of RGO will cause the corrosion resistance of the coating to decrease.The |Z|0.01 of the coating with an RGO dosage of 2.6 wt%is 6.27×102 ?·cm2,which is 1-2 orders of magnitude lower than that of the pure hydroxyproline coating(|Z|0.01=1.15×104?·cm2).In order to further improve the anti-corrosion performance of the coating,it is necessary to improve the uniform dispersion of graphite in the coating.Use A-151 and KH-550 to modify GO,and GMA to modify hydroxy acrylic resin.The covalent bond between GO and the polymer can improve the compatibility of GO and hydroxy acrylic resin is enhanced the anti-corrosion performance of the coating.The modification is characterized by FTIR,XRD,XPS,UV-vis and TGA,and the anti-corrosion performance of the coating and the anti-corrosion mechanism is analyzed through contact angle,salt water resistance test and electrochemical test.