目的 获得一种耐黄变的高防腐转化膜。 方法 将经 KH791 改性的 KH560 与阳离子型聚氨酯进行复合,之后加入无机盐,获得复合钝化液。 将钝化液辊涂于镀锌板上成膜,对膜层进行交流阻抗测试和中性盐雾试验,研究添加的无机盐对膜层耐蚀性的影响,并推测出其反应机理。 结果 阳离子型聚氨酯复合膜的交流阻抗谱上出现了 3 个时间常数,且在 48 h 盐雾试验中腐蚀面积为未添加无机盐的复合膜的 1 / 8 。 结论 KH560 经改性后,分子交联度有所提高。 添加无机盐形成的三层结构体系膜层更能阻挡腐蚀介质的入侵,抗腐蚀性能明显提高。

Objective To obtain highly corrosion-resistant coating with resistance to yellow conversion. Methods Composite passivating fluid was obtained by adding inorganic salts into the composite solution of KH560 modified by KH791 together with cationic polyurethane. Ac impedance test and salt spray test were performed with the coating after the composite passivating liquid was rolled on the galvanized sheet. The influence of the inorganic salts added on the coating corrosion resistance was studied and its reaction mechanism was inferred. Results The ac impedance spectroscopy of the cationic polyurethane composite coating displayed three time constants and in the 48 h salt spray test the corrosion area was only 1 / 8 that of the composite coating without addition of inorganic salts. Conclusion The molecular cross-linking degree was improved after KH560 was modified and the three-layer membrane structure formed by inorganic salt addition could stop the invasion of corrosive medium more effectively, so that its corrosion resistance could be obviously improved.