| 摘要 |
PROBLEM TO BE SOLVED: To obtain a water-based ink with a specific relationship between bubble period and surface tension, having a combination of excellent delivery reliability and high-quality image affordability, thus useful for ink jet printing. SOLUTION: This water-based ink comprises a water-soluble or water- dispersible colorant, water and a moisturizing agent. This ink satisfies the relationship between the surface tension γ (mN/m) and bubble period T (s/ bubble) determined by the maximum bubble pressure method at 25 deg.C, as follows: when T>1.0, γ<50, and when T<=0.2, γ>=40, simultaneously. Besides, this ink pref. contains (A) such a surfactant that its 0.1wt.% aqueous solution satisfies the relationship: when T>1.0, γ<50, specifically, a polyoxyethylene alkyl ether acetic acid salt of formula I [R1 is a 6-14C (branched) alkyl, alkali metal salt, quaternary ammonium salt, etc.] or a dialkylsulfosuccinic acid salt of formula II [R2 is a 5-7C (branched) alkyl] or (B) another surfactant with its 0.1wt.% aqueous solution satisfying the relationship: when T>1.0, γ>=40, specifically, a nonionic surfactant. |
