丙烯酸聚氨酯涂层万宁近海地区自然老化历程与机理

Natural Aging Process and Mechanism of Acrylic Polyurethane Coating in Wanning Coastal Area

选取具备我国典型热带海洋气候条件的万宁试验站,进行丙烯酸聚氨酯涂层(BDC)2 a近海大气的自然老化试验,对其在近海地区的老化历程及老化机理进行了研究;同时在实验室环境下进行了BDC样品的湿热、盐雾、UVA的循环老化试验,对其老化历程进行验证。结果表明:在万宁近海地区,BDC样品老化初期的光泽变化较明显,涂层以水解老化方式为主;老化中期涂层的失效大部分是由腐蚀介质Cl-的侵入而引起的;当老化1 a左右时,老化速度放缓,此时涂层的变化主要是由于光氧化作用;实验室加速循环试验谱湿热(168 h)-盐雾(168 h)-UVA(168 h)基本可以模拟涂层万宁近海地区1 a的变化,以色差为指标,模拟后关联度可达0.926,二者的XPS及FT-IR谱图也非常接近。

Natural aging experiments of acrylic polyurethane coating （BDC） in Wanning experiment station where has a typical tropics ocean climate in China were made for two years, meanwhile, accelerated aging tests including humidity-thermal test, salt spray test and UVA of BDC were carried out in lab. The aging process and mechanism of BDC in Wanning coastal area were verified by the results of accelerated cycle tests. The results showed that BDC gave an obvious change in gloss initially and the hydrolysis degradation occurred primarily. After- wards, the film failure was caused mainly by penetration of corrosive medium Cl-. Approxi- mately one year later, the film failure was mainly caused by photo-oxydation. The results of accelerated cycle tests such as humidity-thermal test （168 h）, salt spray test （168 h） and UVA （ 168 h） could simulate the changes of coatings in natural environment for one year. As viewed from chromatic aberration, the simulated results exhibited a high correlativity 0. 926, meanwhile, XPS and FT-IR showed the similar aging results between natural aging experiment and accelerated cycle test.