Patent ID: 7371274

Claim:
A water-based ink comprising water, a plurality of water-soluble organic solvents, and a water-insoluble coloring material, wherein said water-soluble organic solvents are comprised of at least one good solvent to said water insoluble coloring material and at least one poor solvent to said water-insoluble coloring material, and a total amount A (% by mass) of the good solvent or good solvents in the ink and a total amount B (% by mass) of the poor solvent or poor solvents in the ink are in a ratio A:B of from 10:5 to 10:30 both inclusive, and wherein said water-soluble organic solvents include a poor solvent having a Ka value determined by the Bristow method which is the largest among the Ka values of all the water-soluble organic solvents in the ink, and said water-soluble organic solvents include at least one combination of a good solvent and a poor solvent having Ka values which differ from each other by not less than 0.04.