Abstract: An aqueous ink for ink jet recording contains a titanium oxide particle containing titanium oxide, at least part of the surface of the titanium oxide being covered with alumina and silica in specific proportions, and a compound serving as a dispersant for the titanium oxide particle, the compound being represented by the following general formula (1): where in general formula (1), R1, R2 and R3 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, each R4 is independently an alkylene group having 2 to 4 carbon atoms, X is a single bond or an alkylene group having 1 to 6 carbon atoms, n is 6 to 24, a is 1 to 3, b is 0 to 2 and a + b = 3.

Abstract: An aqueous ink contains a titanium oxide particle, poly(acrylic acid) and potassium ions, in which the titanium oxide particle contains titanium oxide, at least part of the surface of the titanium oxide is covered with alumina and silica, and the poly(acrylic acid) content is 0.05 times or more to 0.40 times or less the alumina content in terms of a mass ratio.

Abstract: An aqueous ink for ink jet recording includes a titanium oxide particle containing titanium oxide, at least part of the surface of the titanium oxide being covered with alumina and silica in specific proportions, in which the titanium oxide particle is dispersed at least by the action of the silica, and the ratio (?1/?1,000) of the viscosity (?1) of the aqueous ink at a shear rate of 1 (1/s) to the viscosity (?1,000) at a shear rate of 1,000 (1/s) is 1.10 times or less.

Abstract: Provided is an aqueous ink capable of recording an image having a good hue as a magenta ink. The aqueous ink is an aqueous ink for ink jet including a first coloring material and a second coloring material. The first coloring material is a compound represented by general formula (1), and the second coloring material is a compound represented by general formula (2). A proportion (% by mass) of a content of the second coloring material to a total content of the first coloring material and the second coloring material in the aqueous ink is 0.60% by mass or more.

Abstract: Provided is an ink capable of recording an image that is excellent in ozone resistance, hardly causes blurring or color change even in a high-humidity environment, and is excellent in humidity resistance. The ink includes a coloring material and a lithium ion. The coloring material includes a compound represented by the following general formula (I) and a content of the lithium ion in the ink is 3.5 times or more in terms of molar ratio with respect to a content of the compound represented by the general formula (I).

Abstract: An ink to be applied to a recording head having a common liquid chamber, pressure chambers developing pressure applied to the liquid, individual channels through which the liquid is introduced into the pressure chambers from the common liquid chamber, and a group of nozzles which communicate with the pressure chambers and eject the liquid, where first nozzles having short individual channels and second nozzles having long ones are alternately arranged at arrangement intervals of less than 30 ?m along one side or sides of the common liquid chamber, contains an aqueous medium, a surfactant and a coloring material. The aqueous medium consists of water and a water-soluble organic compound containing at least one alkanediol and has a surface tension of from 40 mN/m or more to less than 60 mN/m in an environment of temperature 25° C. and humidity 50%.

Abstract: Provided is an ink capable of recording an image that is excellent in ozone resistance, hardly causes blurring or color change even in a high-humidity environment, and is excellent in humidity resistance. The ink includes a coloring material and a lithium ion. The coloring material includes a compound represented by the following general formula (I) and a content of the lithium ion in the ink is 3.5 times or more in terms of molar ratio with respect to a content of the compound represented by the general formula (I).

Abstract: An ink to be applied to a recording head having a common liquid chamber, pressure chambers developing pressure applied to the liquid, individual channels through which the liquid is introduced into the pressure chambers from the common liquid chamber, and a group of nozzles which communicate with the pressure chambers and eject the liquid, where first nozzles having short individual channels and second nozzles having long ones are alternately arranged at arrangement intervals of less than 30 ?m along one side or sides of the common liquid chamber, contains an aqueous medium, a surfactant and a coloring material. The aqueous medium consists of water and a water-soluble organic compound containing at least one alkanediol and has a surface tension of from 40 mN/m or more to less than 60 mN/m in an environment of temperature 25° C. and humidity 50%.

Abstract: An ink to be applied to a recording head having a common liquid chamber, pressure chambers developing pressure applied to the liquid, individual channels through which the liquid is introduced into the pressure chambers from the common liquid chamber, and a group of nozzles which communicate with the pressure chambers and eject the liquid, where first nozzles having short individual channels and second nozzles having long ones are alternately arranged at arrangement intervals of less than 30 ?m along one side or sides of the common liquid chamber, contains an aqueous medium, a surfactant and a coloring material. The aqueous medium consists of water and a water-soluble organic compound containing at least one alkanediol and has a surface tension of from 40 mN/m or more to less than 60 mN/m in an environment of temperature 25° C. and humidity 50%.

Abstract: An ink jet ink providing an image having excellent lightfastness and having sticking resistance and intermittent ejection stability. The ink jet ink is characterized by containing at least a compound represented by the following general formula (I) and a compound represented by the following general formula (II).

Abstract: An ink cartridge for storing ink includes a thermal ink-jet head provided with a heating portion that generates thermal energy for discharging the ink. The heating portion has, on its surface in contact with the ink, a protective layer containing at least one of a silicon oxide, a silicon nitride, and a silicon carbide. The ink contains a substance that dissolves the protective layer and a compound represented by the following formula (1), and the content X (% by mass) of the compound of the formula (1) satisfies a relationship of 1?X?30: Formula (1) R1-A-R2, wherein A represents one selected from —S—, —S(?O)—, and —S(?O)2—, and R1 and R2 each independently represent a group selected from a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an alkenyl group, an acyl group, a carbamoyl group, a carboxyl group, and a sulfonyl group.

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: The present invention provides an ink jet ink, which gives a superior lightfastness to an ink image, has a superior sticking resistance and intermittent ejection stability, and gives a preferable color tone to the image. The ink includes an azo-based dye represented by formula (I) and a water-soluble organic solvent represented by bis(2-hydroxyethyl)sulfone represented by formula (II).

Abstract: An ink set is provided which can suppress bleeding irrespective of the type of recording medium. The ink set includes a plurality of aqueous inks each containing a dye, and has at least a first aqueous ink containing a dye, wherein the difference between the dynamic surface tension of the first aqueous ink at a lifetime of 50 milliseconds and the dynamic surface tension of the first aqueous ink at a lifetime of 500 milliseconds is 7 mN/m or more; and, between the first aqueous ink and at least one type of aqueous ink except the first aqueous ink included in the ink set, dynamic surface tension ?a (mN/m) of an ink A having relatively higher lightness at a lifetime of 500 milliseconds and dynamic surface tension ?b (mN/m) of an ink B having relatively lower lightness at a lifetime of 500 milliseconds satisfy ?5?(?a??b)?3.

Abstract: There is provided an ink cartridge including: a thermal ink-jet head provided with a heat generating portion that generates thermal energy for ejecting ink from an ejection opening, and contains the ink. In the ink cartridge, the heat generating portion has, at its surface in contact with the ink, a protective layer containing at least one selected from the group consisting of a silicon oxide, a silicon nitride, and a silicon carbide; and the ink contains at least one of a polyvalent carboxylic acid and a salt thereof, and the total content of the polyvalent carboxylic acid and the salt thereof is in the range of from 0.001 mmol/l or more to 0.5 mmol/l or less. The ink cartridge shows a small change in driving pulse and a small change in image to be outputted, and provides sufficient ejection property and sufficient printing durability.

Abstract: A mailing ink, an ink tank for mailing, an ink jet recording method for mailing and an ink jet recording apparatus for mailing that can reconcile preferable tint and visibility as indicia with readability by a 2-D bar code reader. The ink is a mailing ink used in ink jet recording. In the mailing ink, the ink tank, the ink jet recording method, and the ink jet recording apparatus, the ink provides an ‘a*’ of from ?10 to 15 and a ‘b*’ of from ?50 to ?15 according to the CIE L*a*b* color system in a printed portion obtained by applying the ink to a recording medium so as to give an application amount of ink of 4.5 mg per square inch, and provides an integrated value of reflection spectrum of 90 or lower in a wavelength region of from 380 nm to 730 nm in the printed portion.

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 to be applied to a recording head having a common liquid chamber, pressure chambers developing pressure applied to the liquid, individual channels through which the liquid is introduced into the pressure chambers from the common liquid chamber, and a group of nozzles which communicate with the pressure chambers and eject the liquid, where first nozzles having short individual channels and second nozzles having long ones are alternately arranged at arrangement intervals of less than 30 ?m along one side or sides of the common liquid chamber, contains an aqueous medium, a surfactant and a coloring material. The aqueous medium consists of water and a water-soluble organic compound containing at least one alkanediol and has a surface tension of from 40 mN/m or more to less than 60 mN/m in an environment of temperature 25° C. and humidity 50%.

Abstract: An ink cartridge includes an ink-jet head and plural liquid chambers storing inks different from each other. The minimum value A1 (g/ml) for the ink densities of the inks stored in the plural liquid chambers and the maximum value B1 (g/ml) for the ink densities of inks each obtained by evaporating 10 mass % of each of the inks stored in the plural liquid chambers satisfy the relationship of (B1?A1)/A1?0.100. A stable image can be obtained, in which, even when the ink cartridge is stored for a long time period at the time of physical distribution, or is stored for a long time period in a state of being mounted on a recording apparatus so that the stored inks are brought into a situation in which the inks are apt to evaporate, a change in color balance is small as compared to an initial state.

Abstract: A mailing ink, an ink tank for mailing, an ink jet recording method for mailing and an ink jet recording apparatus for mailing that can reconcile preferable tint and visibility as indicia with readability by a 2-D bar code reader. The ink is a mailing ink used in ink jet recording. In the mailing ink, the ink tank, the ink jet recording method, and the ink jet recording apparatus, the ink provides an ‘a*’ of from ?10 to 15 and a ‘b*’ of from ?50 to ?15 according to the CIE L*a*b* color system in a printed portion obtained by applying the ink to a recording medium so as to give an application amount of ink of 4.5 mg per square inch, and provides an integrated value of reflection spectrum of 90 or lower in a wavelength region of from 380 nm to 730 nm in the printed portion.