| 摘要 |
There is described a biaxially oriented polypropylene (BOPP) film which has dispersed therein rigid rod like UV absorbers compatible with the polymer such as . (E,E)-1,4- diphenylbuta-1,3-diene (DPBD); (E,E)-1,6-diphenylhexa-1,3,5-triene (DPHT); and beta, beta-carote n e (carotene) at typical concentrations of about 0.01% w/w. These absorbers preferentially align along one of the two orientation axes of the film and allow anisotropy in the film to be covertly detected by the difference in the UV fluorescence spectra of the film in along each axis. This provides a covert means to authenticate the film, which is useful as a substrate for security applications. |
