水性丙烯酸氨基涂层浸泡失效行为研究

Study on Failure Behavior of Waterborne Acrylic Amino Coating

研究丙烯酸氨基涂层的失效行为有助于推进丙烯酸酯乳液在水性涂料中的应用。该文以MMA、BA、MAA、HPMA的共聚物乳液配合氨基树脂制备了水性丙烯酸氨基烤漆,固化后得到丙烯酸涂层并在3.5%(wt.)NaCl溶液中研究了涂层的失效行为。通过扫描电镜(SEM)记录了老化过程中涂层表面缺陷的形成与演化,利用拉曼光谱分析了老化过程中涂层分子结构变化。测试了涂层附着力和接触角的变化。通过电化学阻抗(EIS)综合分析了涂层的防腐性能、孔隙率、吸水率在老化过程中的变化情况。结果表明,浸泡初期涂层表面光滑平整,经浸泡后涂层因吸水出现鼓泡缺陷,涂层聚合物分子结构发生明显改变。涂层低频阻抗模量能够在浸泡240h内保持在106左右,浸泡时间延长至240h时,腐蚀介质透过涂层,涂层防护性能较差,附着力降低至0.35MPa,水接触角仅81.1°。

Studying the failure behavior of acrylic amino coating is helpful to promote the application of acrylate emulsion in waterborne coatings. In this paper, waterborne acrylic amino varnish was prepared by copolymers of MMA, BA, MAA and HPMA with amino resin. Acrylic coatings were obtained after curing, and the failure behavior of the coatings was studied in 3.5%(wt.) NaCl solution. The formation and evolution of coating surface defects during aging were recorded by SEM, and the molecular structures at different depths in the coating during aging were analyzed by Raman spectroscopy. The changes of coating adhesion and contact angle before and after failure were tested. The changes of corrosion resistance, porosity and water absorption of the coating during aging were analyzed by electrochemical impedance spectroscopy(EIS). The results show that the surface of the coating is smooth and flat at the initial stage of immersion. After immersion, the coating has bubbling defects due to water absorption, and the molecular structure of the coating polymer has changed signifi cantly. The low-frequency impedance modulus of the coating can be maintained at about 106 within 240h of immersion. When the immersion time is extended to 240h, the corrosive medium passes through the coating, the protective performance of the coating is poor, the adhesion is reduced to 0.35MPa, and the water contact angle is only 81.1 °.