| 摘要 |
PROBLEM TO BE SOLVED: To obtain an ink which can form a high-quality image and has excellent delivery stability, delivery durability, and storage stability by selecting an ink containing a water-soluble colorant, bishydroxyethyl sulfone, and an aqueous medium and having a specified pH value. SOLUTION: There is provided the ink containing 0.1-15 wt.% colorant comprising a water-soluble dye such as a direct dye or an acid dye; 0.1-30 wt.% bishydroxyethyl sulfone of a structure represented by the formula; and 1-30 wt.% water-soluble organic solvent selected from among amides such as dimethylformamide, ethers such as dioxane, etc., and having a pH of 9.5-12. This ink additionally contains 0.1-20 wt.% urea, especially, 0.2-30 wt.%, in total, urea and bishydroxyethyl sulfone, and, optionally, a surfactant, a pH modifier, a rustproofing agent, a preservative, etc. This ink exhibits desirable delivery performances when it has a surface tension of 30-68 dyn/cm and a viscosity of 15 cP or below. |
