Patent ID: 7604340

Claim:
A water-based ink set for ink-jet recording, comprising a black ink, a yellow ink, a magenta ink and a cyan ink, wherein dynamic surface tensions of each ink as determined by the maximum bubble pressure method at a measurement temperature of 25° C. satisfy the following relationships: σ 1000Bk ≧35 mN/m; (1) |σ 30Y −σ 30Bk |≦5 mN/m; (2) σ 30M ≧30 mN/m,σ 30C ≧30 mN/m; (3) σ 30Y >σ 30M ,σ 30Y >σ 30C ; and (4) σ 30Y +σ 30M ≦93 mN/m,σ 30Y +σ 30C ≦93 mN/m, (5) wherein σ 30Bk , σ 30y , σ 30M and σ 30c are dynamic surface tensions of the blank ink, the yellow ink, the magenta ink, and the cyan ink, respectively at a lifetime of 30 ms, and σ 1000Bk is a dynamic surface tension of the black ink at a lifetime of 1,000 ms.