双(p-乙酰胺基苯氧基)二甲基硅烷改性聚氨酯涂层的耐热性

Heat-resistance of bis(p-acetamidalphnoxy)dimethyl silane modified polyurethane coatings

将双(p-乙酰胺基苯氧基)二甲基硅烷(AAPDS)作为改性扩链剂加入到聚氨酯(PU)涂层的室温固化体系中,以改善PU涂层的耐热性能。运用凝胶时间测定仪和热失重分析仪(TGA)对不同AAPDS加入量对PU涂层的凝胶时间和热失重温度的影响进行了研究;并测试了涂层在金属基体上的附着强度随高温处理时间的变化。结果表明,向涂层固化体系中加入占多元醇总质量4.5%的AAPDS后,固化凝胶时间由未改性时的14.0 min缩短至12.1 min,涂层的初始失重温度和失重5%的温度由273℃和278℃分别提高到296℃和302℃;在400℃下高温处理120 s后附着强度保留率达到80.9%,远高于未改性涂层的57.1%。

The bis （ρ- acetamidalphnoxy） dimethyl silane（AAPDS）was introduced as the chain extender into the PU coatings cured at room temperature to improve the heat - resistance of the PU coatings. The effects of different AAPDS amounts on the gel time and thermal decomposition temperature of PU coatings were investigated by the gel time tester and thermo gravimetric analyzer （TGA）. The adhesive strength changes with the treatment time at high temperature of the coatings on metal substrate were tested. The results showed that the gel time of the coatings with 4.5% AAPDS（based on the total polyol weight） was shortened to 12. 1 min from 14. 0 min of the untreated coatings. The initial dicomposition and 5% decomposition temperature were increased from 273 ℃ and 278 ℃ to 296 ℃ and 302 ℃ respectively. The adhesive strength retention rate of the coatings after treatment at 400 ℃ for 120 s was 80. 9% and much higher than 57.1% of the unmodified coatings.