An Anisotropic Ink Based on Crystalline Nanocellulose: Potential Applications in Security Printing

摘要

Polymer dispersions containing crystalline nanocellulose have been used as birefringent inks. When printed onto dark paper, the letters are darker than the background if viewed without polarizers, while they are brighter than the background if viewed with crossed polarizers. This type of contrast inversion can have applications in security printing and optical authentication.