REVERSIBLE PIEZOCHROMIC SYSTEMS

摘要

The present invention provides a reversible piezochromic system that gives high contrast images upon an application of pressure to the system. The system has a short color-reversal time and can be prepared inexpensively by admixing a suitable electron donating compound and a suitable electron accepting compound. The reversible piezochromic systems of the present invention are useful for preparing a printing ink that can be used to print, for example, banknotes, to prevent forgeries.