| 摘要 |
<p>PURPOSE:To obtain a color ink having a specific composition, excellent in printed image stability, also excellent in color fading nature in color fading by near-infrared rays, thus enabling even to read the letters reprinted on the parts color-faded after printing. CONSTITUTION:This color ink can be obtained by grinding and dispersing, in a liquid substrate (e.g. toluene, methanol), (A) a cationic dye with near- infrared absorption of formula D<+>.A- or formula I (D<+> is cation with near- infrared absorption; A- is anion such as BF<->4 or halogen ion; R1-R4 are each alkyl, aryl, etc.) and (B) a color-fading agent of formula II (R5-R8 are each alkyl, aryl, etc.; Z<+> is quaternary ammonium cation, quaternary pyridinium cation, etc.) (e.g. tetramethyammonium n-butyltriphenylboron), so as to give a mean particle diameter of <=20mum. Specifically, this ink is produced, for example, by mixing the components A and B whih the liquid substrate followed by grinding and dispersin both the components in the substrate suing e.g. a roll mill.</p> |
