Ink, method for improving intermittent dischargeability of ink-jet recording apparatus, method for recording image, recording unit, ink cartridge, ink set, and image recording apparatus

摘要

An ink contains a coloring material and an aqueous medium. The coloring material is composed of a self-dispersion-type carbon black. At least one hydrophilic group is bonded to the surface of the carbon black directly or through another atomic group. A Ka value of the ink determined by a Bristow's test method is less than 1.5, and the total amount of monovalent cations in the ink is in a range of 0.05 to 1 mole/liter. This ink exhibits superior ink-jet recording characteristics.