This invention relates to an ink-jet printing ink which has improved printing stability.
Ink-jet printers are known in the art and have advantages over other printing techniques, such as freedom from noise and attainment of high-speed printing, high-quality printing, and color printing. In the ink-jet printing process, an ink is compressed by an electromechanical transducing-vibration or electrothermal transducing-bubble and a high-pressure ink particle is then ejected from a nozzle for printing.
A disadvantage of ordinary inks used in this process is that ordinary ink contains dissolved gases which upon compression from bubbles or bubble nuclei. This results in blank spots in the printing known as the "missing dot" condition.
For this reason, ink-jet printing inks have been subjected to treatment, such as deaeration or fine filtration, to remove bubble nuclei, and then stored in a bag or vessel having low air permeability.
The disadvantage of these treatment and storage methods is that after a period of time, and particularly when the ink is exposed to high temperatures, bubbles still form in the ink notwithstanding the initial deaeration. Thus, after a period of time or exposure to high temperatures, the ink develops the same problems as untreated ink, i.e. an inability to be uniformly ejected from the nozzle. Thus, the prior art inks for ink-jet printers are subjected to limitations of time and temperature which affect the transportation, shelf-life, storage, and use of the ink.
Accordingly, an ink-jet printing ink which can perform in an ink jet printer after long periods of time and at high temperatures is desired.