| 摘要 |
PROBLEM TO BE SOLVED: To provide an ink capable of providing a good character quality of a black character, high image density and excellent light resistance, capable of enabling a reciprocating printing process to be carried out and a gray image to be formed when forming a color image, and capable of providing an image having no density unevenness of the black ink between reciprocal passages by using the black ink and an ink set in which the ionicity is different from each other. SOLUTION: This ink containing at least (a) a cationic pigment dispersion, (b) a water-soluble organic solvent, (c) water and (d) a salt of a weak acid and a weak base, having >=2 quotient of (a molar conductivity at 0.01 mol/1) divided by (a molar conductivity at 0.1 mol/l) is characterized in that the ink has >=40 mv ζ-potential and >=40 dyne/cm surface tension. |
