Preparation Of Poly (Acrylate-(Vinyl Ester Of Versatic Acid)) Coating On Carbon Steel Surface And Its Electrochemical Properties

In order to adapt to environmental pressure,anti-corrosive coatings are developing towards the direction of waterborne coatings.Due to the poor water and salt spray resistance of acrylic anti-corrosive coatings,as well as the disadvantages of high temperature brittleness and low temperature stichiness,vinyl ester of versatic acid monomer and other functional monomers were introduced to improve the performance of the emulsion and corrosion resistance to metal of its coating.In this paper,dynamic mechanical analysis(DMA)and electrochemical methods were used to optimize the formulation of poly(acrylate-(vinyl ester of versatic acid))emulsion and coatings.The main research contents of this paper are as follows.Firstly,poly(acrylate-(vinyl ester of versatic acid))emulsion was synthesized by semi-continuous seed emulsion polymerization process.MMA,BA,MAA and vinyl ester of versatic acid were used as monomers,KH570 and DAAM were functional monomers,KPS and Na HCO₃ was used as an initiator and a buffer respectively.Based on the principle of emulsion polymerization,the effects of emulsifier type and dosage,monomer composition and crosslinking agent dosage on emulsion synthesis and coating properties were investigated systematically.The influence of the above variables on the particle size,stability,gel rate of emulsion and anti-corrosion of coating was characterized by means of laser particle size analyzer,differential scanning calorimeter(DSC)and contact angle meter.The results show that when the dosage of SR-10 emulsifier,vinyl ester of versatic acid,KH570 and DAAM:ADH is 3.0%,30%,5%,and 2:0.8,respectively,the emulsion particle size is about 124 nm,the conversion rate of monomers is 96.6%and there is no obvious flocs.The water absorption of the coating is less than 10%,the crosslinking degree can reach more than 90%,and the self-corrosion potential is of about-0.369 m V.Secondly,the poly(acrylate-(vinyl ester of versatic acid))emulsion was synthesized by SR-10 emulsifier,and its chemical structure was characterized by FT-IR and ¹H NMR.The viscoelastic properties of the latex film were tested by dynamic mechanical analysis(DMA).The electrochemical impedance spectroscopy(EIS)of the latex coating was carried out by electrochemical workstation,and the eigenvalue and the equivalent circuit method were used for analysis.The results show that the coating is maximum impedance radius and the best anti-corrosion effect as SR-10 emulsifier is 3.2%,and it is also proved that there is an inevitable relationship between crosslinking density and corrosion resistance.Finally,the poly(acrylate-(vinyl ester of versatic acid))emulsion used as the film former,the influence of the amount of film coalescing aid,the pigment volume concentration(PVC),the type of thickener and corrosion inhibitor on the corrosion resistance of the coating were investigated.The results show that the PVC value is 25%,the dosage of the film coalescing aid,250HBR thickener and benzotriazole inhibitor was3.0%,0.8 g and 2%,respectively,the coating has the best anti-corrosion performance.