Abstract: An ink jet ink is provided which can retain good stability and shows superior intermittent ejection stability not only under a low-temperature, low-humidity environment but also a high-temperature, low-humidity environment even when the evaporation of water in the ink progresses. The ink jet ink includes a coloring material and water-soluble organic solvents, wherein the content of the coloring material is less than 7.0 mass %, the water-soluble organic solvents include glycerin and a branched alkanediol having hydroxyl groups at both terminals of its main chain, the content C of glycerin is 6.0 to 12.0 mass %, the content A of the branched alkanediol is 4.0 to 11.0 mass %, and the content A of the branched alkanediol and the total content B of the water-soluble organic solvents satisfy the relationship of 0.30?A/B?0.50.

Abstract: An ink jet recording ink tank includes: an ink retention member, which to hold ink exerts a negative pressure through capillary force; and ink, which is retained in the ink retention member, for which a dynamic surface tension in a lifetime of 50 msec, obtained by a maximum bubble pressure method, is higher than an interfacial tension of the ink retention member, a dynamic surface tension in a lifetime of 5000 msec is lower than the interfacial tension of the ink retention member, and a difference between the dynamic surface tension in the lifetime of 50 msec and the dynamic surface tension in the lifetime of 5000 msec is equal to or greater than 8 mN/m.

Abstract: An image forming method using a black ink containing a pigment, a black ink containing a dye, and a reactive color ink capable of unstabilizing the dispersion state of the pigment in the black ink, wherein the method includes one of the steps of, on at least part of a region to which the black ink is to be applied, applying the reactive color ink, the black ink, and the black ink in that order so as to overlap, thereby applying these inks to a recording medium; and applying the black ink, the black ink, and the reactive color ink in that order so as to overlap, thereby applying these inks to a recording medium.

Abstract: In an ink set having a plurality of inks, the ink set has at least a pigment ink and a dye ink. The pigment ink contains at least water, a surfactant, a self-dispersion pigment, and a poor medium for self-dispersion pigment and/or a salt; a dynamic surface tension of the pigment ink at a lifetime of 50 milliseconds is higher than 47 mN/m. The dye ink contains at least water, a surfactant and a dye. An ink set is provided which can obtain images having a high image density and a superior bleeding resistance without regard to the types of recording mediums.

Abstract: A pigment ink is provided which is used in an ink jet recording apparatus in which ejection orifices for a pigment ink and ejection orifices for at least one type of reactive ink that destabilizes a dispersed state of pigment in the pigment ink are capped with the identical cap provided with a unit for removing an ink in the cap, achieving compatibility between bleeding resistance and reliability. Where a mixed thickening ratio upon mixing the pigment ink and the reactive ink in equal volumes is represented by Y (%) and an ejection orifice-to-ejection orifice distance between the ejection orifice for the pigment ink and the ejection orifice for the reactive ink is represented by X (mm) (provided that X>0), Y and X satisfy a specific relationship.

Abstract: An ink jet ink is provided which can retain good stability and shows superior intermittent ejection stability not only under a low-temperature, low-humidity environment but also a high-temperature, low-humidity environment even when the evaporation of water in the ink progresses. The ink jet ink includes a coloring material and water-soluble organic solvents, wherein the content of the coloring material is less than 7.0 mass %, the water-soluble organic solvents include glycerin and a branched alkanediol having hydroxyl groups at both terminals of its main chain, the content C of glycerin is 6.0 to 12.0 mass %, the content A of the branched alkanediol is 4.0 to 11.0 mass %, and the content A of the branched alkanediol and the total content B of the water-soluble organic solvents satisfy the relationship of 0.30?A/B?0.50.

Abstract: In an ink set having a plurality of inks, the ink set has at least a pigment ink and a dye ink. The pigment ink contains at least water, a surfactant, a self-dispersion pigment, and a poor medium for self-dispersion pigment and/or a salt; a dynamic surface tension of the pigment ink at a lifetime of 50 milliseconds is higher than 47 mN/m. The dye ink contains at least water, a surfactant and a dye. An ink set is provided which can obtain images having a high image density and a superior bleeding resistance without regard to the types of recording mediums.

Abstract: An ink jet recording ink tank includes: an ink retention member, which to hold ink exerts a negative pressure through capillary force; and ink, which is retained in the ink retention member, for which a dynamic surface tension in a lifetime of 50 msec, obtained by a maximum bubble pressure method, is higher than an interfacial tension of the ink retention member, a dynamic surface tension in a lifetime of 5000 msec is lower than the interfacial tension of the ink retention member, and a difference between the dynamic surface tension in the lifetime of 50 msec and the dynamic surface tension in the lifetime of 5000 msec is equal to or greater than 8 mN/m.

Abstract: An ink jet ink which can form images whose bleeding resistance is high and whose bronzing phenomenon is suppressed, is provided. The ink is an ink jet ink for use together with a pigment ink. The ink jet ink is characterized in that: the ink jet ink contains a coloring material, a polyvalent metal and a water-soluble organic solvent(s); the coloring material is at least a compound represented by the general formula (I); a content (mol/g) of the polyvalent metal is 2.0×10?6 mol/g or more and 4.0×10?4 mol/g or less; a total content (mass %) of the water-soluble organic solvent(s) is 25.0 mass % or more with respect to the total mass of the ink; and in a dispersion distance distribution, measured by a small angle X-ray scattering method, of molecular aggregates in the ink jet ink whose coloring material concentration is adjusted to 0.5 mass %, a dispersion distance d75 value corresponding to 75% of a distribution is 12.60 nm or less.

Abstract: A pigment ink is provided which is used in an ink jet recording apparatus in which ejection orifices for a pigment ink and ejection orifices for at least one type of reactive ink that destabilizes a dispersed state of pigment in the pigment ink are capped with the identical cap provided with a unit for removing an ink in the cap, achieving compatibility between bleeding resistance and reliability. Where a mixed thickening ratio upon mixing the pigment ink and the reactive ink in equal volumes is represented by Y (%) and an ejection orifice-to-ejection orifice distance between the ejection orifice for the pigment ink and the ejection orifice for the reactive ink is represented by X (mm) (provided that X>0), Y and X satisfy a specific relationship.

Abstract: An ink jet ink which can form images whose bleeding resistance is high and whose bronzing phenomenon is suppressed, is provided. The ink is an ink jet ink for use together with a pigment ink. The ink jet ink is characterized in that: the ink jet ink contains a coloring material, a polyvalent metal and a water-soluble organic solvent(s); the coloring material is at least a compound represented by the general formula (I); a content (mol/g) of the polyvalent metal is 2.0×10?6 mol/g or more and 4.0×10?4 mol/g or less; a total content (mass %) of the water-soluble organic solvent(s) is 25.0 mass % or more with respect to the total mass of the ink; and in a dispersion distance distribution, measured by a small angle X-ray scattering method, of molecular aggregates in the ink jet ink whose coloring material concentration is adjusted to 0.5 mass %, a dispersion distance d75 value corresponding to 75% of a distribution is 12.60 nm or less.

Abstract: An image forming method using a black ink containing a pigment, a black ink containing a dye, and a reactive color ink capable of unstabilizing the dispersion state of the pigment in the black ink, wherein the method includes one of the steps of, on at least part of a region to which the black ink is to be applied, applying the reactive color ink, the black ink, and the black ink in that order so as to overlap, thereby applying these inks to a recording medium; and applying the black ink, the black ink, and the reactive color ink in that order so as to overlap, thereby applying these inks to a recording medium.