Abstract: Provided herein is an aqueous ink, which is excellent in both image density and fixing ability irrespective of the kind of a recording medium even when the volume of an ink droplet is small and has such excellent properties that white stripes are not caused even when high-speed recording is conducted. The aqueous ink comprises at least water, a water-soluble organic solvent, a water-insoluble coloring material, a surfactant and a poor medium for the water-insoluble coloring material and/or a salt. The dynamic surface tension of the aqueous ink at a lifetime of 50 milliseconds determined by a maximum bubble pressure method is higher than 47 mN/m, and the dynamic surface tension at a lifetime of 5,000 milliseconds determined by the maximum bubble pressure method is 38 mN/m or lower.

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: 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 storage stability and ejection characteristics even when it is stored for a long period of time. The aqueous ink comprises a polymer having hydroxyl groups and a pigment, wherein a proportion of a content of a polymer that is not adsorbed on the pigment out of the polymer having hydroxyl groups to the content of the pigment in the ink is 2.0 mass % or more, and a content (mass %) of the polymer that is not adsorbed on the pigment out of the polymer having hydroxyl groups is 0.20 mass % or less based on the total mass of the ink.

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 aqueous ink used together with a black ink containing a self-dispersion pigment, wherein the aqueous ink contains a reactive component for destabilizing the dispersion state of the self-dispersion pigment, the dynamic surface tension of the aqueous ink at a lifetime of 30 milliseconds is 41 mN/m or more, and the dynamic surface tension of the aqueous ink at a lifetime of 500 milliseconds is from 28 mN/m or more to 38 mN/m or less as determined by a maximum bubble pressure method.

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: An aqueous ink to be used together with a pigment ink containing a pigment and a polymer, wherein the aqueous ink contains a reactive component for destabilizing the dispersion state of the pigment, the dynamic surface tension of the aqueous ink at a lifetime of 30 milliseconds is 41 mN/m or more, and the dynamic surface tension of the aqueous ink at a lifetime of 500 milliseconds is from 28 mN/m or more to 38 mN/m or less as determined by a maximum bubble pressure method.

Abstract: Provided herein is an aqueous ink, which is excellent in both image density and fixing ability irrespective of the kind of a recording medium even when the volume of an ink droplet is small and has such excellent properties that white stripes are not caused even when high-speed recording is conducted. The aqueous ink comprises at least water, a water-soluble organic solvent, a water-insoluble coloring material, a surfactant and a poor medium for the water-insoluble coloring material and/or a salt. The dynamic surface tension of the aqueous ink at a lifetime of 50 milliseconds determined by a maximum bubble pressure method is higher than 47 mN/m, and the dynamic surface tension at a lifetime of 5,000 milliseconds determined by the maximum bubble pressure method is 38 mN/m or lower.

Abstract: Novel conditions in the physical properties of an ink have been found out to provide an aqueous ink, which can give a high image density and achieve excellent fixing ability. The aqueous ink comprises at least water, a water-soluble organic solvent, a surfactant and a coloring material, wherein the dynamic surface tension at a lifetime of 50 milliseconds as determined by a maximum bubble pressure method is 49 mN/m or more, and the dynamic surface tension at a lifetime of 5,000 milliseconds as determined by the maximum bubble pressure method is 38 mN/m 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: 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 storage stability and ejection characteristics even when it is stored for a long period of time. The aqueous ink comprises a polymer having hydroxyl groups and a pigment, wherein a proportion of a content of a polymer that is not adsorbed on the pigment out of the polymer having hydroxyl groups to the content of the pigment in the ink is 2.0 mass % or more, and a content (mass %) of the polymer that is not adsorbed on the pigment out of the polymer having hydroxyl groups is 0.20 mass % or less based on the total mass of the ink.

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 poor medium for a polymer that is not adsorbed on the pigment of the polymer having hydroxyl groups, and wherein when the segment constituting the polymer that is not adsorbed on the pigment of the polymer having hydroxyl groups is comprised of a segment A having hydroxyl groups and a segment B having no hydroxyl group, at least one of the poor medium is a good medium for either one of the segment A and the Segment B.