| 摘要 |
<p>PURPOSE:To obtain ink which does not cause precipitation of any solid, by detecting the pH of an aq. dye soln. and feeding a pH adjustor to thereby keep the pH constant over a long period of time, thus keeping good dispersibility and thermal stability. CONSTITUTION:The pH of an aq. dye soln. in a liquid tank 1 is detected by a pH detector and the detected value is fed through an A/D converter 16 to a control device 6 and judged whether the value is within the range of preset values. When the value is out of the optimum pH range, a valve 9 for a pH adjusting means 4 is opened to feed a pH adjustor to the dye soln. 2, where the pH is adjusted. When the value is within the optimum pH range preset, a discharge valve 15 is opened to feed the dye soln. 2 to an ink preparing tank 17, where the dye soln. 2 is mixed with a solvent 14 for ink, which is fed from a solvent feeder 10.</p> |
