Abstract: The present invention aims to provide an ink jet black ink which can improve weatherability, optical density and sticking recovery property of nozzles of a recording head. According to the present invention, an ink jet black ink is provided which comprises at least a coloring-material and a water-soluble organic solvent, wherein the coloring material is a compound represented by the following general formula (I) or a salt thereof, and the water-soluble organic solvent is a water-soluble organic solvent having a relative permittivity of from 30.0 or more to less than 70.0 at 20° C. and capable of dissolving the compound represented by the following general formula (I) or a salt thereof, by 1.0 mass % or more at 25° C., and is in a content of 50.0 mass % or more with respect to the total content of all water-soluble organic solvents contained in the ink jet black ink.

Abstract: To provide an ink jet black ink which has a favorable tint for ink jet black ink, provides high ozone fastness, a high image density, and high sticking recovery property, and is capable of suppressing the decomposition of a compound represented by the following general formula (I) or a salt thereof at the time of storage for a long time period. The ink jet black ink is an ink jet black ink comprising at least a compound represented by the following general formula (I) or a salt thereof as a coloring material, and ethylene glycol or diethylene glycol, wherein the content of ethylene glycol or diethylene glycol is 15 mass % or more and 30 mass % or less with respect to the total mass of the ink jet black ink.

Abstract: An object of the present invention is to provide an ink jet black ink by which an image quality comparable to that of a silver halide photograph is obtained with a compatibility between a high fastness and a high image quality when the ink is printed on a recording medium, and which is excellent in optical density and color tone particularly in half tone, and is also excellent in gas resistance. The present invention provides an ink jet black ink comprising a dye and a black pigment, wherein the dye is at least one kind selected from the group consisting of compounds represented by the following formula (I) or salts thereof, and compounds represented by the following formula (II) or salts thereof.

Abstract: It is an object of the present invention to provide a black ink for an ink jet which possesses preferable color as a black ink for an ink jet, can attain high ozone resistance, high image density and sticking recovery property, and can suppress the decomposition of the compound represented by the general formula (I) or salt thereof during long-term storage. According to the present invention, there is provided a black ink for an ink jet characterized by comprising at least a compound represented by the following general formula (I) or a salt thereof, characterized in that the black ink comprises at least one moisture-retaining nitrogen compound, and the pH of the ink and the pH of the ink after storing for 10 days in an environment at a temperature of 60° C. are 9.5 or less.

Abstract: An ink set includes inks each containing a colorant and an aqueous medium, wherein in a fading test under conditions that cause fading corresponding to pseudo-indoor sunlight fading through a window for 3 years or more, the difference between respective images' ?E, the images being produced with the respective inks, is 10 or less in a CIELAB color space display system, and each of the images has a residual ratio of reflection density of 70% or more. By using the ink set including the color inks with which images having substantially the same fading ?E after long-term storage are produced, the color balance of a recorded image can be maintained after long-term storage.

Abstract: Magenta ink exhibiting excellent coloration on various recording materials is provided according to the present invention. The magenta ink can realize high image densities and can produce images having superior light resistance.

Abstract: A water-based ink that comprises a water-soluble anionic colorant, an aluminum ion and an acid ion, wherein the content of the acid ion is more than that of the aluminum ion, and the content of the water-soluble anionic colorant is 20 to 1,000 times as much as that of the acid ion by molar ratio.

Abstract: An ink set includes inks each containing a colorant and an aqueous medium, wherein in a fading test under conditions that cause fading corresponding to pseudo-indoor sunlight fading through a window for 3 years or more, the difference between respective images' &Dgr;E, the images being produced with the respective inks, is 10 or less in a CIELAB color space display system, and each of the images has a residual ratio of reflection density of 70% or more. By using the ink set including the color inks with which images having substantially the same fading &Dgr;E after long-term storage are produced, the color balance of a recorded image can be maintained after long-term storage.

Abstract: The present invention provides an ink set, an ink jet recording apparatus, an ink jet recording method, a recording unit, and an ink cartridge, which can produce ink jet color images in which the color balance does not easily become unstable even if the image is stored for a long time, and in which the color images have greater durability so that degradation of the visual appearance is not easily recognizable even if the image is stored for a long time. The ink set includes a first aqueous ink and a second aqueous ink having the same color tone, the second ink having a lower coloring material content than that of the first ink, and the degree of fading of an image produced with the second ink is the same as or lower than that of an image produced with the first ink.

Abstract: An ink set which comprises a black ink containing an aqueous medium and a pigment dispersed in the aqueous medium by an action of an ionic group, and at least two color inks each containing a coloring material and an aqueous medium, wherein (i) respective images formed with the respective color inks have the same &Dgr;E or have the difference in &Dgr;E that is 10 or less in a CIELAB color space display system in a fading test under conditions that cause fading corresponding to pseudo-indoor sunlight fading through a window for 3 years or more, and (ii) at least one of the color inks contains at least one of a coloring material and an additive that destabilize dispersion stability of the pigment in the black ink. The ink set can provide a high quality multicolor image keeping color balance after long preservation and showing less bleeding between black and color regions.

Abstract: The present invention provides an ink set, an ink jet recording apparatus, an ink jet recording method, a recording unit, and an ink cartridge, which can produce ink jet color images in which the color balance does not easily become unstable even if the image is stored for a long time, and in which the color images have greater durability so that degradation of the visual appearance is not easily recognizable even if the image is stored for a long time. The ink set includes a first aqueous ink and a second aqueous ink having the same color tone, the second ink having a lower coloring material content than that of the first ink, and the degree of fading of an image produced with the second ink is the same as or lower than that of an image produced with the first ink.

Abstract: An ink set includes inks each containing a colorant and an aqueous medium, wherein in a fading test under conditions that cause fading corresponding to pseudo-indoor sunlight fading through a window for 3 years or more, the difference between respective images' &Dgr;E, the images being produced with the respective inks, is 10 or less in a CIELAB color space display system, and each of the images has a residual ratio of reflection density of 70% or more. By using the ink set including the color inks with which images having substantially the same fading &Dgr;E after long-term storage are produced, the color balance of a recorded image can be maintained after long-term storage.

Abstract: An ink set which comprises a magenta ink and a cyan ink, where the magenta ink comprises a coloring material of general formula (I) and a compound of general formula (II), and the cyan ink comprises a coloring material having a copper phthalocyanine structure and a compound of general formula (II): which can provide color images excellent in light fastness at a mixed color region of the magenta and the cyan inks.

Abstract: An ink set which comprises a black ink containing an aqueous medium and a pigment dispersed in the aqueous medium by an action of an ionic group, and at least two color inks each containing a coloring material and an aqueous medium, wherein (i) respective images formed with the respective color inks have the same &Dgr;E or have the difference in &Dgr;E that is 10 or less in a CIELAB color space display system in a fading test under conditions that cause fading corresponding to pseudo-indoor sunlight fading through a window for 3 years or more, and (ii) at least one of the color inks contains at least one of a coloring material and an additive that destabilize dispersion stability of the pigment in the black ink. The ink set can provide a high quality multicolor image keeping color balance after long preservation and showing less bleeding between black and color regions.

Abstract: The invention provides an ink including a water-soluble coloring material and bis(hydroxyethyl)sulfone in an aqueous medium and having a pH of from 9.5 to 12. The ink permits stable formation of high-quality images on a wide variety of recording media, and has excellent ejection stability, ejection durability and storage stability.

Abstract: The present invention provides an ink set, an ink jet recording apparatus, an ink jet recording method, a recording unit, and an ink cartridge, which can produce ink jet color images in which the color balance does not easily become unstable even if the image is stored for a long time, and in which the color images have greater durability so that degradation of the visual appearance is not easily recognizable even if the image is stored for a long time. The ink set includes a first aqueous ink and a second aqueous ink having the same color tone, the second ink having a lower coloring material content than that of the first ink, and the degree of fading of an image produced with the second ink is the same as or lower than that of an image produced with the first ink.

Abstract: An ink set which comprises a magenta ink and a cyan ink, where the magenta ink comprises a coloring material of general formula (I) and a compound of general formula (II), and the cyan ink comprises a coloring material having a copper phthalocyanine structure and a compound of general formula (II): 1

Abstract: An ink set includes inks each containing a colorant and an aqueous medium, wherein in a fading test under conditions that cause fading corresponding to pseudo-indoor sunlight fading through a window for 3 years or more, the difference between respective images' &Dgr;E, the images being produced with the respective inks, is 10 or less in a CIELAB color space display system, and each of the images has a residual ratio of reflection density of 70% or more. By using the ink set including the color inks with which images having substantially the same fading &Dgr;E after long-term storage are produced, the color balance of a recorded image can be maintained after long-term storage.

Abstract: Magenta ink exhibiting excellent coloration on various recording materials is provided according to the present invention. The magenta ink can realize high image densities and can produce images having superior light resistance. The magenta ink contains first and second coloring materials represented by the following general formulae 1 and 2, respectively, and a water-based medium.

Abstract: An ink absorbent member is prepared for holding an ink stored in an ink storing section in an ink jet cartridge. The ink absorbent member contains not more then 0.20% by weight, on the basis of the member, of a fraction of soluble matters in a liquid containing an organic polar solvent incapable of reacting with the ink absorbent member such as monohydric alcohols or alkyl ethers of polyhydric alcohols.