Abstract: Inkjet ink contains a pigment, a hydrosoluble solvent, and water, wherein the pigment is represented by the following chemical formula 1 and has a CuK? X-ray diffraction spectrum having a wavelength of 1.541 ? such that no main peak is observed at a Bragg (2?±0.2°) angle in a range of 2? of from 28.0° to 29.0°, wherein R represents a hydrogen atom, a methyl group, or a chlorine atom.

Abstract: An ink composition contains a pigment represented by the following chemical formula 1; a hydrosoluble solvent; and water, wherein the pigment satisfies the following relation 1:0.040<Y/X<0.200 (Relation 1), where, in a CuK? X-ray diffraction spectrum having a wavelength of 1.541 ?, X represents a peak intensity at a Bragg (2?±0.2°) angle in a range of 2? of from 26.5° to 27.5° and Y represents a peak intensity at a Bragg (2?±0.2°) angle in a range of 2? of from 11.0° to 11.

Abstract: An ink for inkjet recording contains water, an organic solvent, a pigment, and a compound represented by the following Chemical formula 1: In Chemical formula 1, M+'s each, independently represent protons, cations of alkali metals, ammonium ions, or organic ammonium ions.

Abstract: An ink composition contains a pigment, a polymer having a structure unit having a diphosphonic acid group, a hydrosoluble solvent, and water, and satisfies the following A and B. A: The pigment is represented by the following chemical formula 1a or chemical formula 1b. As for Chemical formula 1a, the pigment satisfies the relation 1: Y/X?0.800, where X and Y represent peak intensities at a Bragg (2?±0.2°) angle in a CuK? X-ray diffraction spectrum, when the pigment is represented by Chemical formula 1b, the pigment satisfies the relation 2: Y?/X??0.200, where X? and Y? represent peak intensities at a Bragg (2?±0.2°) angle in a CuK? X-ray diffraction spectrum, B. the structure unit having a diphosphonic acid group is represented by Chemical formula 2.

Abstract: Inkjet ink contains a pigment, a hydrosoluble solvent, and water, wherein the pigment is represented by the following chemical formula 1 and has a CuK? X-ray diffraction spectrum having a wavelength of 1.541 ? such that no main peak is observed at a Bragg (2?±0.2°) angle in a range of 2? of from 28.0° to 29.0°, wherein R represents a hydrogen atom, a methyl group, or a chlorine atom.

Abstract: An inkjet recording ink set, which contains at least: a black pigment ink; and a color pigment ink, wherein the black pigment ink contains a black pigment treated with an anionic surfactant, and a black pigment coated with a resinous polymer, and water, and the black pigment ink is a pigment dispersion liquid where the black pigment treated with the anionic surfactant and the black pigment coated with the resinous polymer are dispersed in the water, and wherein the color pigment ink contains a color pigment, a nonionic surfactant, and water, and the color pigment ink is a pigment dispersion liquid where the color pigment is dispersed in the water with assistance of the nonionic surfactant.

Abstract: An ink for inkjet recording includes water; a hydrosoluble organic solvent; a pigment; and a polymer including a first structural unit represented by the following formula (1): wherein R1 represents a hydrogen atom or a methyl group; and M+ represents at least one member selected from the group consisting of alkali metal ions, organic amine ions and hydrogen ions; and a second structural unit represented by the following formula (2) or (3): wherein each of R2 and R3 represents a methyl group or a hydrogen atom; n represents an integer of 18; x represents 0 or an integer of 2.

Abstract: An ink for inkjet recording, which is used for recording on a paper having a concentration of an eluted Ca ion of from 1.0×10?4 to 5.0×10?4 g/g when dipped in pure water. The ink includes at least a pigment, a pigment dispersant, a water-soluble organic solvent and water. The pigment dispersant is a copolymer synthesized using at least (1) unsaturated ethylene monomer having a phosphoric acid group or a phosphonic acid group and (2) unsaturated ethylene monomer having an alkyl group having 12 to 22 carbon atoms.

Abstract: An inkjet recording ink, including: water; a water-soluble solvent; a pigment; and a phosphoric acid group-containing copolymer, wherein the phosphoric acid group-containing copolymer contains at least a structural unit represented by General Formula (1) and a structural unit represented by General Formula (2): where in General Formula (1), R1 represents a hydrogen atom or a methyl group, M+ represents a proton, an alkali metal ion, or an organic ammonium ion, k and l are each an integer of 0 to 6, with the proviso that the case where k and l are 0 at the same time is excluded, where in General Formula (2), R2 represents a hydrogen atom or a methyl group, R3 represents an alkyl group having 1 to 4 carbon atoms, n and m are each an integer of 0 to 30, with the proviso that n+m is 2 to 30.

Abstract: An ink for inkjet recording includes water; a hydrosoluble organic solvent; a pigment; and a polymer including a first structural unit represented by the following formula (1): wherein R1 represents a hydrogen atom or a methyl group; and M+ represents at least one member selected from the group consisting of alkali metal ions, organic amine ions and hydrogen ions; and a second structural unit represented by the following formula (2) or (3): wherein each of R2 and R3 represents a methyl group or a hydrogen atom; n represents an integer of 18; x represents 0 or an integer of 2.

Abstract: An ink for inkjet recording including a pigment, a penetrating agent and water, wherein the pigment includes: an ozone-oxidized carbon black, including carbon black oxidized by ozone and having a volatile matter content of the carbon black of 10% by mass to 20% by mass and a BET specific surface area of 90 m2/g to 150 m2/g; and a resin-coated carbon black, including: carbon black; and a resin present on a surface of the carbon black.

Abstract: An inkjet ink that contains at least water; a water-soluble organic solvent; a pigment; and a copolymer or a salt thereof. The copolymer or the salt thereof has at least a structural unit represented by Formula 1, a structural unit represented by Formula 2, and a structural unit represented by Formula 3 or 4.

Abstract: An ink composition contains a pigment; a copolymer containing a phosphoric acid group or phosphonic acid group; a hydrosoluble solvent; and water, wherein the pigment is represented by the following chemical formula 1 and satisfies the following relation 1: Y<X<0.8, where X represents a peak intensity at a Bragg (2?±0.2°) angle in a range of 2? of from 5.5° to 6.0° and Y represents a peak intensity at a Bragg (2?±0.2°) angle in a range of 2? of from 26.5° to 27.5° to a CuK? X-ray having a wavelength of 1.541 ?. where R each, independently represents monovalent groups selected from hydrogen atoms, methyl groups, or chlorine atoms.

Abstract: An ink composition contains a pigment; a copolymer comprising a phosphoric acid group or phosphonic acid group; a hydrosoluble solvent; and water, wherein the pigment is represented by the following chemical formula 1 and satisfies the following relation 1: Y/X?0.20??Relation 1 where X represents a peak intensity at a Bragg (2?±0.2°) angle in a range of 2? of from 26.5° to 27.5° and Y represents a peak intensity at a Bragg (2?±0.2°) angle in a range of 2? of from 11.0° to 11.5° to a CuK? X-ray having a wavelength of 1.541 ?.

Abstract: An ink for inkjet recording includes water; a hydrosoluble solvent, a pigment, and a copolymer including a salt of a diphosphonic acid group. The copolymer including a salt of a diphosphonic acid group includes structural units having the following formulae (1) and (2): X represents an alkylene group having 1 to 3 carbon atoms, each of R1 and R2 represents a hydrogen atom or a methyl group, M+ represents an alkali metal ion, an organic ammonium ion or a proton and Z1 represents a hydrocarbon group having 6 to 22 carbon atoms. The alkali metal ion or the organic ammonium ion and the proton may be mixed, and half or more of the M+ are alkali metal ions or the organic ammonium ions.

Abstract: An ink for inkjet recording, which is used for recording on a paper having a concentration of an eluted Ca ion of from 1.0×10?4 to 5.0×10?4 g/g when dipped in pure water. The ink includes at least a pigment, a pigment dispersant, a water-soluble organic solvent and water. The pigment dispersant is a copolymer synthesized using at least (1) unsaturated ethylene monomer having a phosphoric acid group or a phosphonic acid group and (2) unsaturated ethylene monomer having an alkyl group having 12 to 22 carbon atoms.

Abstract: An inkjet recording ink including a carbon black, a dispersant, a polyurethane resin particle, and water, where the carbon black is a channel black, a gas black, or a mixture of channel black and a gas black, and the polyurethane resin particle is an anionic self-emulsifying ether-based polyurethane resin particle, wherein the anionic self-emulsifying ether-based polyurethane resin particle has an acid value of 40 to 120 and a mass average molecular weight of 500 to 50,000, and an average primary particle diameter of 20 nm or less.

Abstract: An inkjet ink including water, a pigment, a polymer, and a hydrazine compound. The polymer does not include an anionic unit and includes a first unit having a carbonyl group capable of reacting with a hydrazino group, and a second unit having at least one of an amino group, a dimethylamino group, and a diethylamino group. The content of the first unit is from 40% to 90% by weight based on the weight of the polymer, and the inkjet ink has a pH of not less than 9.

Abstract: An inkjet recording ink, including: water; a water-soluble solvent; a pigment; and a phosphate group-containing copolymer, wherein the phosphate group-containing copolymer includes a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2): wherein, in the general formula (1), R1 represents either of a hydrogen atom and a methyl group; and M+ represents any of an alkali metal ion, an organic amine ion and a hydrogen ion, one-half or more of the M+ in the copolymer is an alkali metal ion or an organic amine, and the remainder is a hydrogen ion; wherein, in the general formula (2), R2 represents either of a hydrogen atom and a methyl group.

Abstract: An inkjet recording ink, including: water; a water-soluble solvent; a pigment; and a phosphate group-containing copolymer, wherein the phosphate group-containing copolymer includes a structural unit represented by the following general formula (1) and a structural unit represented by the following structural formula (1): wherein, in the general formula (1), R1 represents either of a hydrogen atom and a methyl group; and M+ represents any of an alkali metal ion, an organic ammonium ion, an organic amine ion and a hydrogen ion, one-half or more of the M+ in the copolymer is an alkali metal ion, an organic ammonium ion or an organic amine, and the remainder is a hydrogen ion: