马来酸酐聚丁二烯改性聚氨酯涂层的耐水及耐蚀性研究

Water Tolerance and Corrosion Resistance of Polyurethane Coatings Modified by MA-g-Polybutadiene

目的改善聚氨酯涂层的耐水性和耐蚀性等综合性能。方法采用可反应型橡胶马来酸酐聚丁二烯(MAPB)化学改性聚氨酯,并通过红外光谱、接触角、耐水性及电化学阻抗谱等对复合涂层的结构与性能进行表征。结果通过比较分析红外光谱(FT-IR)中改性前后聚氨酯基团对应吸收峰的变化,确定了MAPB成功对聚氨酯进行化学改性。随着马来酸酐丁二烯用量的增加,改性聚氨酯涂料表面疏水性增强,吸水率降低,物理机械性能也得到提高。当加入MAPB含量约为3%~5%时,复合涂层的接触角由75°提高到了95°,吸水率由1.5%降低到最低约0.5%,硬度由3H提高到4H,附着力从4B提高为5B。另外,随着浸泡时间的增加,改性涂层的阻抗值下降的更缓慢,表明MAPB的加入提高了涂层的耐腐蚀性能,尤其是含3%马来酸酐丁二烯改性聚氨酯涂层的耐蚀性表现最优异,这也得到盐雾试验的进一步验证。结论加入约3%的马来酸酐丁二烯改性聚氨酯可大幅降低涂层的吸水率,同时涂层的耐蚀性等综合性能得到改善,这主要归因于可反应基团参与交联提高了涂层的致密度,及其主链烯烃的疏水特性提高了涂层阻隔水和腐蚀介质渗透扩散的能力。

The work aims to improve the comprehensive performances of polyurethane coatings,including water tolerance,corrosion resistance,etc.Reactive rubber-maleic anhydride polybutadiene(MAPB)was used to modify the polyurethane coating and the structure and properties of composite coating were characterized by Fourier transform infrared spectroscopy,contact angle,water tolerance,electrochemical impedance spectrum,etc.By comparing and analyzing the changes of absorption peaks of polyurethane groups before and after modification in Fourier transform infrared spectroscopy(FT-IR),it was confirmed that MAPB successfully modified polyurethane.The addition of MAPB in PU coatings resulted in the enhancement of hydrophobicity,decrease of water absorption and improvement of mechanical performances.When the content of MAPB was added to about 3%~5%,the contact angle increased from 75°to 95°,the water absorption reduced from 1.5%to a minimum of about 0.5%,the hardness increased from 3H to 4H,and the adhesion increased from 4B to 5B.In addition,with the increase in immersion time in NaCl solution,the resistance values of the modified coatings decreased more slowly,indicating that the addition of MAPB improved the corrosion resistance of the PU coatings,especially the coating containing 3%MAPB performed the best in corrosion resistance,which was further verified by the results of salt spray test.MAPB of about 3%can greatly reduce the water absorption of the PU coatings,and improve their overall performance including corrosion resistance,because the coating compactness is improved through chemical cross-linking reaction and the hydrophobic character of the olefinmain chain enhances blocking ability upon the diffusion of water and corrosive media.