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1. Rewritable phosphorescent paper by the control of competing kinetic and thermodynamic self-assembling events

Author

Takuzo Aida, Akihiro Kishimura, Takashi Yamashita, and Kentaro Yamaguchi

Subjects
Paper, Mechanochromic luminescence, Materials science, Bistability, Ultraviolet Rays, Information Storage and Retrieval, Product Labeling, Security Measures, Liquid crystal, Materials Testing, Ultraviolet light, General Materials Science, Thermal printing, Thermodynamic process, Luminescent Agents, Inkwell, business.industry, Mechanical Engineering, General Chemistry, Condensed Matter Physics, Kinetics, Mechanics of Materials, Luminescent Measurements, Optoelectronics, Printing, Thermodynamics, Ink, Phosphorescence, business, Crystallization
Abstract

Security inks have become of increasing importance. They are composed of invisible substances that provide printed images that are not able to be photocopied, and are readable only under special environments. Here we report a novel photoluminescent ink for rewritable media that dichroically emits phosphorescence due to a structural bistability of the self-assembled luminophor. Long-lasting images have been developed by using conventional thermal printers, which are readable only on exposure to ultraviolet light, and more importantly, are thermally erasable for rewriting. Although thermally rewritable printing media have already been developed using visible dyes and cholesteric liquid crystals, security inks that allow rewriting of invisible printed images are unprecedented. We realized this unique feature by the control of kinetic and thermodynamic processes that compete with one another in the self-assembly of the luminophor. This strategy can provide an important step towards the next-generation security technology for information handling.

Published
2004

2. Rewritable phosphorescent paper by the control of competing kinetic and thermodynamic self-assembling events.

Author

Kishimura A, Yamashita T, Yamaguchi K, and Aida T

Subjects
Kinetics, Luminescent Agents analysis, Luminescent Measurements, Materials Testing, Security Measures, Thermodynamics, Ultraviolet Rays, Crystallization methods, Information Storage and Retrieval methods, Ink, Luminescent Agents chemistry, Luminescent Agents radiation effects, Paper, Printing methods, Product Labeling methods
Abstract

Security inks have become of increasing importance. They are composed of invisible substances that provide printed images that are not able to be photocopied, and are readable only under special environments. Here we report a novel photoluminescent ink for rewritable media that dichroically emits phosphorescence due to a structural bistability of the self-assembled luminophor. Long-lasting images have been developed by using conventional thermal printers, which are readable only on exposure to ultraviolet light, and more importantly, are thermally erasable for rewriting. Although thermally rewritable printing media have already been developed using visible dyes and cholesteric liquid crystals, security inks that allow rewriting of invisible printed images are unprecedented. We realized this unique feature by the control of kinetic and thermodynamic processes that compete with one another in the self-assembly of the luminophor. This strategy can provide an important step towards the next-generation security technology for information handling.

Published
2005
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