| 摘要 |
<p>The invention utilises 1,2-Dihydroquinolines (DHQ) in the preparation of photochromic ink compositions. By incorporating an acid in the ink compositions or by providing an electron-withdrawing N-substituent in the DHQ, ink compositions are produced which colour irreversibly when exposed to U.V. light. The ink compositions are useful for forming security or validation markings or in a lithographic process which avoids the need for a wet development step.</p> |
