机动车号牌用油墨及反光膜的红外光谱分析

Examination of Ink and Retro-reflective Sheeting of Vehicle Registration Plate by FTIR

目的建立适合机动车号牌用油墨及反光膜的傅里叶红外光谱(Fourier Transform Infrared Spectrometer,FTIR)分析方法。方法使用FTIR法对源自国内8个省市的54个机动车号牌用油墨及反光膜样品进行了全面的分析,并通过传统红外光谱解析的方式对样品的红外吸收特征进行了总结。利用光谱软件Omnic 8.2的谱图管理功能建立了名为"蓝色油墨层"、"树脂层"和"背胶层"的3个检索谱库。结果在多个层结构物质中,蓝色油墨层、树脂层以及背胶层的化学物质适宜使用FTIR法检验,所有样品的背胶层化学成分相似;54个机动车号牌样品根据蓝色油墨层化学成分可以分为5大类,根据树脂层化学成分可以分为4大类。将每个样品的蓝色油墨层、树脂层和背胶层的红外谱图,在对应的谱库里进行全谱范围的相关性检索和平方微分差检索,获取相应的匹配度及其概率密度分布。结论相关性检索和平方微分差检索的比对结果表明,相关性检索结果更适合机动车号牌用油墨及反光膜的红外光谱比对分析。

Objective To establish a specified analytical method for the examination of micro trace evidence of ink and retro- reflective sheeting, collected from vehicle registration plates. Method The ink samples and retro-reflective sheeting samples of 54 vehicle registration plates, which were collected from 8 domestic provinces and cities, were analyzed by F13R. Using Ohmic 8.2 software, 3 spectrum libraries entitled ＂blue ink layer＂, ＂resin layer＂ and ＂adhesive layer＂ were established. The spectra of three layers of each sample were searched in the corresponding library with relevance and square differential algorithm. When two samples were compared, the final matching degree was obtained by the combination of the 3 searching results. Results Among all the layers of a vehicle registration plate, the blue ink layer, resin layer and adhesive layer were suitable for FI＇IR analysis. The spectra of adhesive layer of the tested samples were similar. 54 vehicle registration plate samples could be divided into 5 categories according to the spectra of their blue ink layer, or into 4 categories according to the spectra of their resin layer. Conclusion The relevance search is more suitable than the square differential retrieval search in the comparative analysis of ink and retro-reflective sheeting of vehicle registration plate by FTIR.