| 摘要 |
Disclosed herein are a security film and a process for preparation thereof. The security film comprises a directional retroreflective layer (1), an information layer (2) which can change color following to light angle, a reflective layer (3) and a support layer (4) which are combined in turn. The materials of the support layer (4) and the reflective layer (3) are high molecular resin and material with high reflectivity respectively, and the thickness of the reflective layer (3) is nanoscale. The material of the information layer (2) is chiral polymer which can change color following to light angle with helical structure or cellulose material which can change color following to light angle, and the former is a condensation product of a chiral compound and a compound with functional group, and the latter is composed of cellulose derivative and polymerisable monomer. The directional retroreflective layer (1) is composed of spheres, which are made of optical material, embedded in the support layer (4). The refractive index of the material of the directional retroreflective layer (1) is 1.9-1.93. |
