| 摘要 |
PROBLEM TO BE SOLVED: To obtain an ink reduced in attack against a head member without detriment to storage stability and realizing a high water resistance and high print quality by incorporating water, a water-soluble colorant, a cationic water- soluble polymer, and a carboxyl-containing organic acid or a salt thereof into the ink. SOLUTION: This ink comprises deionized water; 0.5-20 wt.% water-soluble colorant selected from among alkali-soluble colored substances such as dyes and pigments; 0.1-20 wt.% cationic water-soluble polymer such as e.g. a homo- or co-polymer of e.g. polyethyleneimide having a structure selected among ethyleneimine, allylamine, diallylamine, etc., and 0.01-10 wt.% carboxyl-containing organic acid (salt) such as an organic acid such as acetic acid, benzoic acid, or the like or a sodium salt thereof. This ink additionally contains a pH modifier such as sodium hydroxide, 5-50 wt.% humectant comprising an aqueous organic solvent such as ethylene glycol or sorbitol, and a penetration accelerator such as a lower alcohol, a cellosolve, or the like. |
