Abstract: A water-based ink set for ink-jet recording is provided. According to this ink set, graininess in a low density printed part can be reduced without reducing a color reproduction range in red and magenta directions in a high density printed part. In addition, the color reproduction range in the red direction can be extended to improve the vividness of red color. The water-based ink set for ink-jet recording includes a magenta ink and a red ink. The magenta ink is a light magenta ink having a lightness (L*) of about 50 or more in the L*a*b* colorimetric system. Preferably, the ink set further includes a light cyan ink having a lightness (L*) of about 60 or more and a blue ink and/or a green ink.

Abstract: The water-based ink set for ink-jet recording includes a cyan ink and a blue ink, or a cyan ink and a green ink. The cyan ink is a light cyan ink having a lightness (L*) of about 60 or more in the L*a*b* colorimetric system. A normal cyan ink having a lightness (L*) of about 60 or less in the L*a*b* calorimetric system is not included in the ink set.

Abstract: A water-based ink set for ink-jet recording includes at least a yellow ink, a magenta ink and a cyan ink. At least one color ink of the yellow, magenta and cyan inks includes a first ink and a second ink which have different hue angles h having therebetween the color range of the normal color of the color ink. Preferably, the yellow ink includes a greenish yellow ink having a hue angle h of about 95° to about 110° and a reddish yellow ink having a hue angle h of about 70° to about 85°; the magenta ink includes a reddish magenta ink having a hue angle h of about 0° to about 10° and a violetish magenta ink having a hue angle h of about 340° to about 350°; and the cyan ink includes a bluish cyan ink having a hue angle h of about 250° to about 260° and a greenish cyan ink having a hue angle h of about 230° to about 240°.

Abstract: A water based ink set for ink-jet recording has a yellow ink, a magenta ink and a cyan ink each having at least a coloring agent, water and a water soluble organic solvent. The coloring agent of each of the black ink and the red ink is a pigment and the coloring agent of each of the yellow ink, the magenta ink and the cyan ink is a water soluble dye. The black ink and the red ink each have a dynamic surface tension at a lifetime of 100 ms of 40 mN/m or more and 45 mN/m or less as measured by a maximum bubble pressure method at 25° C.

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: A water base ink for ink-jet recording contains a surfactant represented by the following formula (1) or (2), dipropylene glycol, a coloring agent, and water: CH3—(CH2)11—O—(CH2CH2O)z—H(2) In the formula (1), R represents alkyl group, and x and y represent integers which satisfy x+y=5 to 15. In the formula (2), z represents an integer of not more than 9. The performance of initial introduction into a recording head is satisfactory, and it is possible to simultaneously reduce the feathering and the color bleed even when the recording is performed on regular paper.

Abstract: In a water base ink set for ink-jet recording including a pigment-based black ink and a dye-based yellow ink, a first water-soluble dye in which a number of counter ion or ions per one molecule is not more than 3 and a hue angle h* is 95° to 105° is used, as the dye used in the yellow ink, together with a second water-soluble dye in which a number of counter ion or ions per one molecule is not more than 3 and a hue angle h* is 75° to 85°; or 30° to 70°; or 0° to 30° or 350° to 360°. When the ink set is applied to a general ink-jet printer with a simple maintenance system, the coagulation of black pigment in the printer and the blurring or bleeding on the printing paper are prevented, thereby realizing a satisfactory and complex coloring of the dye-based yellow ink.

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: A water base ink set for ink-jet recording includes a black ink containing water, a black pigment and a water-soluble organic solvent and a color ink containing water, a dye, and a water-soluble organic solvent. The black pigment is a negatively-chargeable and self-dispersible pigment. The dye has a fluorescein structure. The color ink further contains an alkylamine ethylene oxide adduct. The water-soluble organic solvent contained in the black ink is same as that contained in the color ink. With the ink set, not only the bleeding hardly occurs but also satisfactory discharge stability is obtained even when an ink-jet recording is performed on a regular paper.

Abstract: A water base ink for ink-jet recording contains 0.1% by weight to 4.0% by weight of C.I. Direct Yellow 132; not less than 0.5% by weight of glycol ether having a melting point of not more than ?45°C.; and a water-soluble organic solvent in which a solubility of C.I. Direct Yellow 132 at 20° C. is not less than 5%. The ink satisfies 0.2?B/A and 3?C/A. B/A represents a weight ratio of the glycol ether to the C.I. Direct Yellow 132 contained in the ink, and C/A represents a weight ratio of the water-soluble organic solvent to the C.I. Direct Yellow 132 contained in the ink. The stability in long-term storage after the evaporation of water or at low temperatures can be obtained even when C.I. Direct Yellow 132 is used in the water-base ink for the ink-jet recording.

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 ink set for ink-jet recording includes a black ink containing a negatively charged self-dispersing black pigment and a water-soluble polyvalent alcohol alkyl ether; and a yellow ink containing a water-soluble anionic yellow dye in which a number of counter ion or ions per one molecule is not more than 3, a surfactant based on amine represented by the following general formula (1), and a water-soluble polyvalent alcohol alkyl ether; R—N—(CH2CH2O)xH(CH2CH2O)yH??(1) wherein R represents an alkyl group or an alkenyl group having a number of carbons of 8 to 18, and x+y is 5 to 15. Accordingly, the water ink set in which no bleeding or no coagulation of the pigment occur is provided.

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 comprises water, a coloring agent, a water-soluble organic solvent, and a benzotriazole-based metal-inactivating agent and alkanolamine. When the ink is used in an ink-jet recording apparatus which has the metal member containing nickel or nickel alloy in an ink supply passage, nickel is eluted from the metal member in an amount of not more than 50 ppm. The ink makes it possible to perform stable jetting operation for a long term without causing any deterioration of metal members of a discharge head due to the metallic corrosion and the elution of nickel into the ink.

Abstract: A water base ink for ink-jet recording contains an amine compound selected from the group consisting of N-n-butylethanolamine, 1,4-bis(3-aminopropyl)piperazine, benzylamine, and an amine compound represented by a specified structural formula, a surfactant having a specified structural formula, a coloring agent, and water. It is possible to obtain a satisfactory rub resistance and a high printing quality with a sharp outline without causing any feathering on a recorded image. Further, it is possible to obtain a long term nozzle discharge stability by suppressing any corrosion on a metal member of a discharge head unit of an ink-jet recording apparatus.

Abstract: An ink set for ink-jet recording includes a first ink which contains glycerol and a first coloring agent, and a second ink which contains a water-soluble organic solvent incompatible with glycerol and a second coloring agent and which does not contain glycerol. The first ink and the second ink are mixed with each other at a low speed. Therefore, the inks permeate into the paper before the inks are mixed with each other. Thus, it is possible to avoid the color bleeding.

Abstract: A water base ink set for ink-jet recording comprises a black ink which contains a black pigment, water, and a water-soluble organic solvent, and a color ink which contains a dye, water, a water-soluble organic solvent, and at least one compound represented by the following formulas (1) to (3), wherein the nozzle clog-up at an ink-jet head and the malfunction of a purging pump, which would be otherwise caused by the aggregation of the black ink, can be avoided: R1—O—(CH2CH2O)x—SO3.Na??(1) wherein R1 represents a straight chain alkyl group having a number of carbon atoms of 16 to 22, and x=20 to 30 is satisfied in the formula (1); wherein l+m+n+o+p+q=20 to 100 is satisfied in the formula (2); and wherein R2 represents a straight chain alkyl group having a number of carbon atoms of 16 to 22, and y=100 to 300 is satisfied in the formula (3).

Abstract: A water base ink set for ink-jet recording comprises a first ink which contains an anionic dye, and a second ink which contains a cationic dye. At least one of the first and second inks contains at least two glycols selected from the group consisting of diethylene glycol, triethylene glycol, and polyethylene glycol, polyvinyl pyrrolidone, and water. The ink set makes it possible to stably discharge the ink by means of an ink-jet head, and it realizes vivid recording which is highly reliable and highly accurate and which provides good color balance.