反应型乳化剂及其水性环氧涂料的制备和耐蚀性能

Preparation and Corrosion Resistance of Ionic Reactive Emulsifier and Its Waterborne Epoxy Resin

目的制备一种低VOC、低毒性的水性环氧树脂涂料。方法通过N,N-二甲基乙二胺与环氧树脂E51反应,然后利用冰乙酸中和成盐,制得一种反应型水性环氧树脂乳化剂,再与环氧树脂E51及四种胺类固化剂(651、GT19、DL19、SG)按一定的比例混合搅拌均匀,于电极表面涂覆,固化成膜后封装。采用显微红外光谱仪(Micro-FTIR)表征乳化剂的结构,采用动态光散射粒度分析仪(ZETA)测试乳化剂乳化E51后得到的乳液粒径。通过电化学阻抗谱和极化曲线测试,研究四种固化剂固化成膜的水性环氧涂层在3.5%NaCl溶液中的耐蚀性。结果当乳化剂与E51的质量比为1∶1时,乳液平均粒径最小为52 nm,分布最均匀,体系最稳定。用固化剂651固化得到的涂层硬度最高,附着力最强,交联密度最高,涂层断面较为致密,在浸泡60 h后,仍具有较高的阻抗模值5.23×104??cm2和较低的自腐蚀电流密度2.0×10-7 A/cm2,对基底具有较好的腐蚀防护作用。结论制得的水性环氧树脂涂料对基底具有良好的防护性能,适用于环保型低VOC涂料领域。

The work aims to fabricate a new waterborne epoxy resin coating with low VOC and low toxicity.An aqueous epoxy resin emulsifier was prepared by reaction of epoxy E51 with N,N-dimethylethylenediamine and then neutralized to salt with glacial acetic acid obtain a reactive water-based epoxy emulsifier.Reactive water-based epoxy emulsifier was mixed with epoxy resin E51 and four types of amine-based curing agents(651,GT19,DL19,SG)based on certain proportion and then coated on the electrode surface and sealed after being cured to film.The structure of the emulsifier was characterized by Micro-FTIR spectrometer.The particle size of the emulsion obtained by emulsifying the emulsifier E51 was tested by a dynamic light scattering particle size analyzer(ZETA).Electrochemical impedance spectroscopy and polarization curve tests were conducted to study the corrosion resistance of four curing agent-cured waterborne epoxy coatings in 3.5%NaCl solution.When the mix proportion of emulsifier and E51 was 1∶1,the average size of emulsion was the minimum,distribution was uniform and the system was stable.The coatings obtained with 651 curing agent had the maximum hardness and the strongest adhesion.Cross-linking density was the highest and coating cross section was the densest.After immersed in 60 hours,the coating still had a higher impedance modulus value of 5.23×10^4Ω·cm2 and a lower self-corrosion current density of 2.0×10^-7 A/cm^2,thus exhibiting significant anti-corrosion properties for the base carbon steel.The prepared waterborne epoxy resin coating has good protective performance for the steel substrates and is suitable for the field of environment-friendly low VOC coatings.