轿车罩光清漆中位阻胺光稳定剂(HALS)的ESR研究

ESR Study on the HALS in Automotive Clearcoats

以热固性改良型丙烯酸类轿车罩光清漆为研究对象,采用电子自旋共振技术(ESR)测定了经自然、人工加速、盐雾和湿热等方式老化的样品中自由基的信号.研究分析各种老化过程中产生的自由基,证明位阻胺光稳定剂(HALS)在自然老化和人工加速老化下,起到延缓老化作用的活性主体是来源于HALS的稳态氮氧自由基(NO·).根据样品中稳态氮氧自由基(NO·)的浓度,讨论了HALS抗老化作用的机理.证实了HALS被氧化后产生的活性主体NO·存在1个循环再生过程.

Electron spin resonance spectroscopy (ESR) has been used to measure the free radicals in automotive clearcoats prepared by variant aging methods such as weathered aging, accelerated aging, salt-mist aging and damp-heat aging. The signals of free radicals which were produced in various aging processes have been investigated. The steady-state nitroxyl radical (NO^(·)) derived from hindered amine light stabilizer (HALS) was demonstrated to act as aging resistance in automotive clearcoats. Based on the steady-state concentration of nitroxyl radical in aging automotive clearcoats, the aging resistance mechanism of HALS has been discussed. It has been proved that there is a recycle in which the active agent of NO^(·) can be reproduced when HALS is oxidated.