Abstract: A water based ink set for ink-jet recording includes a yellow ink, a magenta ink, a cyan ink, a black ink, and a red ink and/or a blue ink each including at least a coloring agent, water and a water soluble organic solvent. In the water based ink set, a water soluble dye is employed as the coloring agent of each of the yellow ink, the magenta ink and the cyan ink, and a pigment is employed as the coloring agent of each of the black ink and the red ink and/or the blue ink. In an ink-jet recording method employing the water based ink set for ink-jet recording, the red ink and the magenta ink are employed together for a magenta-ink-recording portion, and the blue ink and the cyan ink are employed together for a cyan-ink-recording portion.

Abstract: An ink cartridge for ink-jet recording apparatus includes an ink tank usable in an ink-jet recording apparatus and a water base ink filled in the ink tank. In the ink cartridge, the ink tank is formed of polyolefin containing a sorbitol derivative as a crystal-nucleating agent, and the pH of the water base ink filled in the tank has been adjusted to be not less than 4.0 to less than 8.0. This makes it is possible to prevent the sorbitol derivative, contained in the polyolefin as the crystal-nucleating agent, from depositing in the water base ink filled in the ink tank.

Abstract: A water base ink for ink-jet recording contains self-dispersible carbon black as a coloring agent. The total content of an organic acid having a number of carbon or carbons of 1 to 6 and a salt of the organic acid is not more than 400 ppm. The organic acid having a number of carbon or carbons of 1 to 6 includes monocarboxylic acid, dicarboxylic acid and oxy acid, and the salt of the organic acid includes salts of these acids. When the water base ink is used in an ink-jet recording apparatus, the discharge stability of the ink is improved.

Abstract: An ink set for ink-jet recording includes a pigment-based ink containing a negatively chargeable and self-dispersible pigment as a coloring agent and a dye-based ink containing an anionic dye as a coloring agent, and the ink set satisfies the following expression (1): Dci<1.1×Pci+0.0001??(1) wherein “Dci” represents an amount of counter ion (mol/g) of the anionic dye contained in the dye-based ink, and “Pci” represents an amount of counter ion (mol/g) of the self-dispersible pigment contained in the pigment-based ink. The pigment aggregation can be greatly suppressed, and the high quality printing can be stably performed when the ink set for ink-jet recording composed of the pigment-based ink and the dye-based ink is carried on an ink-jet printer provided with a conventional maintenance system that is simple and at low cost.

Abstract: A water base ink for ink-jet recording includes carbon black as a coloring agent and water. The content of chlorine ion contained in the ink is not more than 8 ppm. The ink may be added with 1,2,3-benzotriazole as a rustproofing agent. Even when oxygen is contained in an amount of about 9 ppm in the ink, the corrosion of a discharge section, which would be otherwise caused by chlorine ion, can be avoided even in the case of the use for a printer which uses a metal member for the discharge section.

Abstract: A water base pigment ink for ink-jet recording contains a pigment, a propylene glycol derivative which has a saturation vapor pressure of 2 to 10 hPa and an octanol-water distribution coefficient log P of 0 to 1.35, and dipropylene glycol-n-propyl ether. The propylene glycol derivative is contained in the ink by 0.25 to 1.5% by weight, and the dipropylene glycol-n-propyl ether is contained in the ink by 0.5 to 1% by weight. The ink is excellent in the paper surface drying performance. Further, it is possible to avoid the occurrence of the feathering and the blank stripes in letters.

Abstract: A water base ink for ink-jet recording contains a self-dispersing type pigment, glycol ether, and water. In the glycol ether, the number of carbon atoms of an ethylene oxide moiety is not less than 8, and the solubility in water at 25° C. is not less than 1%. The ink reduces the blurring of a recorded image which would be otherwise caused by the feathering on the paper surface. The ink is excellent in drying performance on the paper surface, and the ink makes it possible to stably disperse the pigment.

Abstract: A water base ink for ink-jet recording contains a self-dispersing type pigment, glycol ether, and water. In the glycol ether, the number of carbon atoms of an ethylene oxide moiety is not less than 8, and the solubility in water at 25° C. is not less than 1%. The ink reduces the blurring of a recorded image which would be otherwise caused by the feathering on the paper surface. The ink is excellent in drying performance on the paper surface, and the ink makes it possible to stably disperse the pigment.

Abstract: A water base ink for ink-jet recording is provided, which makes it possible to perform the discharge operation stably and highly accurately for a long period of time without deteriorating a metal, for example, due to corrosion and/or dissolution even when the ink makes contact with the metal composed of nickel or an alloy containing nickel for a long period of time. The water base ink for ink-jet recording is usable for an ink-jet recording apparatus provided with an ink-jet head having a metal member which is composed of nickel or the alloy containing nickel and which is disposed at least in an ink supply passage for supplying the ink to a discharge section. The water base ink for ink-jet recording contains potassium p-tert-butylbenzoate, a coloring agent which is dispersible or soluble in water, water, and a water-soluble organic solvent.