Laser‐addressed full‐color photo‐quality rewritable sheets based on thermochromic systems with leuco dyes

Abstract

We have developed a laser‐addressed full‐color photographic quality rewritable sheet. The sheet was composed of a vertically stacked Cyan/Magenta/Yellow‐thermochromic system with a mixture of leuco dyes, developers and photothermal conversion agents in a polymer matrix. The sheet was simply manufactured by roll‐to‐roll (R2R) processes. Writing and erasing were performed by scan of near‐infrared laser light. It achieved full‐color photographic quality images with a wide color gamut with 70% coverage of the Specifications for Web Offset Publications (SWOP) standards and a high resolution of 426 ppi. Clear rewritability has also been confirmed. Non‐contact laser writing has other advantages in that it can create an image under a protection film, and it has form factor flexibility. We have developed a reliability model for high‐temperature storage and a light fastness test. This model showed a good agreement with experimental data, and the lifetime of an image was estimated to be over 8 years under ambient conditions. This technology will create applications for on‐demand rewritable image design while saving power and reducing the use of paper, which will eventually contribute to a sustainable society.