| 摘要 |
PROBLEM TO BE SOLVED: To obtain a water-base ink which can give a print of good water resistance and does not cause plug at the tip of an ink jet head by mixing a water-soluble dye having a structure of an ammonium salt or substituted ammonium salt of a carboxyl group with a combination of an acidic amino acid with a basic substance in a specified ratio. SOLUTION: The molar ratio of the basic substance to the acidic amino acid is 0.5-2. The content of the aqueous dye used is usually 0.1-20 wt.% based on the entire ink weight. The acidic amino acid used is glutamic acid, aspartic acid, or such amino acid in which the alkyl is a substituted one. The content of the acidic amino acid used is usually 0.01-20 wt.% based on the entire ink weight. The basic substance is particularly desirably a basic nitrogen compound such as monoethanolamine, diethanolamine, or triethanolamine. The solvent used is a mixed solvent comprising water and a water-soluble organic solvent. |
