Abstract: An aqueous ink containing silver particles, a first reducing agent and a second reducing agent, wherein the first reducing agent is a compound that has an oxidation-reduction potential R1 (mV) satisfying R1<0, and the second reducing agent is a compound that has an oxidation-reduction potential R2 (mV) satisfying R2?0 and that is at least one selected from a group consisting of tertiary amines and polyhydric alcohols in which a plurality of hydroxy groups are included in one of two structures divided according to a position between any one of two adjacent carbon atoms of the longest carbon chain in the molecule.

Abstract: Provided is an ink jet recording method capable of recording an image excellent in color developability while suppressing ink deposition. The ink jet recording method includes ejecting an aqueous ink from an ejection orifice of a recording head based on image data to record an image on a recording medium and ejecting the heated ink to an ink receiving member from the ejection orifice based on preliminary ejection data. The aqueous ink contains a pigment and a resin dispersant for dispersing the pigment and satisfies at least one of requirement (1): the resin dispersant is a water-soluble acrylic resin having an acid value of 135 mgKOH/g or less and requirement (2): the aqueous ink further contains a water-soluble acrylic resin having an acid value of 135 mgKOH/g or less. The pigment is carbon black whose cumulative 50% particle size in volume-based particle size distribution is 80 nm or less.

Abstract: An aqueous ink containing silver particles, a first reducing agent and a second reducing agent, wherein the first reducing agent is a compound that has an oxidation-reduction potential R1 (mV) satisfying R1<0, and the second reducing agent is a compound that has an oxidation-reduction potential R2 (mV) satisfying R2?0 and that is at least one selected from a group consisting of tertiary amines and polyhydric alcohols in which a plurality of hydroxy groups are included in one of two structures divided according to a position between any one of two adjacent carbon atoms of the longest carbon chain in the molecule.

Abstract: Provided is an aqueous ink that enables the recording of images having high optical density and excellent toughness and has excellent reliability. An aqueous ink for ink jet includes a pigment, a resin having an anionic group, a salt and a water-soluble organic solvent. The pigment is a self-dispersible pigment in which an anionic group is bonded to the particle surface of carbon black directly or through another atomic group, the resin has a weight-average molecular weight of 20,000 or less, the water-soluble organic solvent includes glycerol and an additional solvent other than glycerol, and the content (% by mass) of the additional solvent relative to the content (% by mass) of glycerol in terms of mass ratio is 0.6 times or less.

Abstract: To provide an aqueous ink that can suppress the dissolution of silicon or a silicon compound contained in a recording head, can be stably, continuously ejected for a long time, and enables the recording of an image having excellent glossiness. An aqueous ink for ink jet includes a pigment, a resin dispersant for dispersing the pigment, an alkanolamine and a urethane resin. The pigment is a solid solution containing C.I. Pigment Red 122 and C.I. Pigment Violet 19, and the proportion (% by mass) of the C.I. Pigment Red 122 is 10% by mass or more to 90% by mass or less based on the total mass of the solid solution.

Abstract: To provide an aqueous ink for ink jet enabling the recording of an image having excellent character quality and excellent highlighter resistance immediately after the recording. An aqueous ink for ink jet includes a pigment and a urethane resin. The urethane resin has a unit derived from a polyisocyanate, a unit derived from a polyol having no acid group and a unit derived from a polyol having an acid group, the proportion of a unit derived from the polyol having an acid group present at the molecular terminal relative to the whole unit derived from the polyol having an acid group is 30% or less, and the aqueous ink has a dynamic surface tension of 55 mN/m or more at a lifetime of 10 msec.

Abstract: To provide an aqueous ink that can suppress the dissolution of silicon or a silicon compound contained in a recording head, can be stably, continuously ejected for a long time, and enables the recording of an image having excellent glossiness. An aqueous ink for ink jet includes a pigment, a resin dispersant for dispersing the pigment, an alkanolamine and a urethane resin. The pigment is a solid solution containing C.I. Pigment Red 122 and C.I. Pigment Violet 19, and the proportion (% by mass) of the C.I. Pigment Red 122 is 10% by mass or more to 90% by mass or less based on the total mass of the solid solution.

Abstract: To provide an aqueous ink for ink jet enabling the recording of an image having excellent character quality and excellent highlighter resistance immediately after the recording. An aqueous ink for ink jet includes a pigment and a urethane resin. The urethane resin has a unit derived from a polyisocyanate, a unit derived from a polyol having no acid group and a unit derived from a polyol having an acid group, the proportion of a unit derived from the polyol having an acid group present at the molecular terminal relative to the whole unit derived from the polyol having an acid group is 30% or less, and the aqueous ink has a dynamic surface tension of 55 mN/m or more at a lifetime of 10 msec.

Abstract: Provided is an ink jet recording method capable of recording an image excellent in color developability while suppressing ink deposition. The ink jet recording method includes ejecting an aqueous ink from an ejection orifice of a recording head based on image data to record an image on a recording medium and ejecting the heated ink to an ink receiving member from the ejection orifice based on preliminary ejection data. The aqueous ink contains a pigment and a resin dispersant for dispersing the pigment and satisfies at least one of requirement (1): the resin dispersant is a water-soluble acrylic resin having an acid value of 135 mgKOH/g or less and requirement (2): the aqueous ink further contains a water-soluble acrylic resin having an acid value of 135 mgKOH/g or less. The pigment is carbon black whose cumulative 50% particle size in volume-based particle size distribution is 80 nm or less.

Abstract: Provided is an aqueous ink that enables the recording of images having high optical density and excellent toughness and has excellent reliability. An aqueous ink for ink jet includes a pigment, a resin having an anionic group, a salt and a water-soluble organic solvent. The pigment is a self-dispersible pigment in which an anionic group is bonded to the particle surface of carbon black directly or through another atomic group, the resin has a weight-average molecular weight of 20,000 or less, the water-soluble organic solvent includes glycerol and an additional solvent other than glycerol, and the content (% by mass) of the additional solvent relative to the content (% by mass) of glycerol in terms of mass ratio is 0.6 times or less.

Abstract: The present invention preferably provides an ink including an organic pigment, a water-soluble resin and a surfactant that allows images having high color developability to be obtained independently of the type of recording medium, even when a small amount of ink is applied. Preferably, the organic pigment is a phosphonic acid-type self-dispersible pigment, the acid value of the water-soluble resin is 100 mg KOH/g to 160 mg KOH/g, the surfactant is an ethylene oxide adduct of a higher alcohol selected from the group consisting of a linear primary alcohol, a linear secondary alcohol and an isoalkyl alcohol, the HLB value of the surfactant as determined by the Griffin method is 13.0 or more, and the mass ratio of the content (% by mass) of the surfactant in the ink to the content (% by mass) of the water-soluble resin in the ink is 0.07 to 0.70.

Abstract: An ink jet ink contains a polyurethane polymer and a self-dispersing pigment. The polyurethane polymer has units derived from a polyisocyanate, a polyol having no acid group, and a diol having an acid group. The molar ratio of the percentage of the urethane bond in the polyurethane polymer to the percentage of the urea bond in the polyurethane polymer is 85.0/15.0 or more and 100.0/0 or less. The ink jet ink may be capable of producing an image having high optical density, scratch resistance, and highlighter resistance, and which has excellent ink ejection stability and can reduce image deflection caused by face wetting.

Abstract: An aqueous ink for ink jet contains a self-dispersible pigment in which a first functional group including a phosphonic acid group and a second functional group including at least one of a carboxylic acid group and a sulfonic acid group are bonded to a particle surface, wherein a surface charge amount derived from the phosphonic acid group included in the above-described first functional group is 0.3 micromoles/m2 or more, a total surface charge amount derived from the carboxylic acid group and the sulfonic acid group included in the above-described second functional group is 1.0 micromoles/m2 or more, and a total surface charge amount derived from anionic groups included in the above-described first functional group and the above-described second functional group is 2.0 micromoles/m2 or more and 8.0 micromoles/m2 or less.

Abstract: The invention provides an aqueous ink comprising a polymer having hydroxyl groups and a pigment, which can provide images excellent in scratch resistance and highlighter resistance and can inhibit the seeping out phenomenon of the polymer and the deterioration of ejection characteristics even when it is stored for a long period of time. The aqueous ink comprises a polymer having hydroxyl groups, a pigment and a water-soluble organic solvent, wherein the water-soluble organic solvent comprises a polyhydric alcohol having a value of number of hydroxyl groups/number of carbon atoms in its molecule of 0.50 or less.

Abstract: A set of an ink containing a self-dispersible pigment and a water-soluble resin, which is a copolymer having a unit derived from (meth)acrylic acid, and a reaction liquid containing a surfactant, which is an ethylene oxide adduct of a higher alcohol of a linear primary or secondary alcohol or an isoalkyl alcohol and has a HLB value of 13.0 or more determined by the Griffin method, and having buffering ability in an acid region. Content of the surfactant in the reaction liquid is 0.20 times or more in terms of mass ratio as much as total content of the pigment and water-soluble resin.

Abstract: A set of an ink containing a pigment dispersed by a water-soluble resin and having the surface tension of 38 mN/m or less and a reaction liquid containing a polyvalent metal ion and a surfactant, which is an ethylene oxide adduct of a higher alcohol of a linear primary or secondary alcohol or an isoalkyl alcohol, and has a HLB value of 13.0 or more as determined by the Griffin method. The content of the polyvalent metal ion in the reaction liquid is 10.0 times or more in terms of molar ratio as much as an amount of an acidic group derived from the water-soluble resin in the ink and the content of the surfactant in the reaction liquid is 0.15 times or more in terms of mass ratio as much as the total content of the pigment and water-soluble resin in the ink.

Abstract: An aqueous ink for ink jet contains a self-dispersible pigment in which a first functional group including a phosphonic acid group and a second functional group including at least one of a carboxylic acid group and a sulfonic acid group are bonded to a particle surface, wherein a surface charge amount derived from the phosphonic acid group included in the above-described first functional group is 0.3 micromoles/m2 or more, a total surface charge amount derived from the carboxylic acid group and the sulfonic acid group included in the above-described second functional group is 1.0 micromoles/m2 or more, and a total surface charge amount derived from anionic groups included in the above-described first functional group and the above-described second functional group is 2.0 micromoles/m2 or more and 8.0 micromoles/m2 or less.

Abstract: The invention provides an aqueous ink comprising a polymer having hydroxyl groups and a pigment, which can provide images excellent in scratch resistance and highlighter resistance and can inhibit the seeping out phenomenon of the polymer and the deterioration of ejection characteristics even when it is stored for a long period of time. The aqueous ink comprises a polymer having hydroxyl groups, a pigment and a water-soluble organic solvent, wherein the water-soluble organic solvent comprises a polyhydric alcohol having a value of number of hydroxyl groups/number of carbon atoms in its molecule of 0.50 or less.

Abstract: An ink jet ink contains a polyurethane polymer and a pigment. The polyurethane polymer has units derived from a polyisocyanate, a polyether polyol having no acid group, and a diol having an acid group. The pigment is dispersed using a polymer other than the polyurethane polymer. The molar ratio of the percentage of the urethane bond in the polyurethane polymer to the percentage of the urea bond in the polyurethane polymer is 85.0/15.0 or more and 100.0/0 or less.

Abstract: An ink jet ink contains a polyurethane polymer and a pigment. The polyurethane polymer has units derived from a polyisocyanate, a polyether polyol having no acid group, and a diol having an acid group. The pigment is dispersed using a polymer other than the polyurethane polymer. The ratio of the percentage of the urethane bond in the polyurethane polymer to the percentage of the urea bond in the polyurethane polymer is 85.0/15.0 or more and 98.5/1.5 or less.