Abstract: The ink set of the present invention provides a high ejection stability, gives an image having an excellent hue, light-resistance and waterproofness and improves the image preservability under severe conditions in ink jet recording, in which the ink set comprising a plurality of inks different in hues, wherein the plurality of inks includes a yellow ink containing a coloring agent that is a dye having: a ?max of from 390 nm to 470 nm; an I(?max+70 nm)/I(?max) ratio of not greater than 0.4, in which I(?max) is the absorbance at ?max and I(?max+70 nm) is the absorbance at (?max+70 nm); and a forced fading rate constant of not greater than 5.0×10?2 [hour?1], an ink cartridge having the ink set received therein, an ink jet printer comprising the ink cartridge mounted therein and an image recording method.

Abstract: The object of the present invention is to provide an inkjet recording ink ensuring excellent ejection stability even after aging of the ink and also exhibiting excellent weather resistance; provide an inkjet recording ink ensuring less blurring of the image drawn, in addition to excellent ejection stability and weather resistance; and provide a yellow ink and a dark yellow ink, which can contribute to realization of a pictorial quality with excellent color balance as a constituent ink of an ink set. These objects of the present invention can be achieved by an inkjet recording ink including an aqueous medium containing a yellow dye, particularly, a yellow dye represented by formula (1), having spectral absorption characteristics such that the maximum absorption wavelength is in the region from 390 to 470 nm and the absorption long-wave end has a tailing of a specified value or less, and antioxidative characteristics such that the ozone enforced discoloration rate constant is 5.0 x 10?2 [hour?1] or less.

Abstract: An inkjet recording ink including an aqueous medium having dissolved therein a phthalocyanine dye, wherein the phthalocyanine dye is a water-soluble dye having an oxidation potential more positive than 1.0 V (vs SCE) and the ink includes a water-miscible organic solvent having a vapor pressure of 2,000 Pa or less at 20° C.; and an inkjet recording method using the ink.

Abstract: A black ink for inkjet recording having an aqueous medium containing a dye in which ?max of the absorption spectrum in an aqueous solution is in the region from 500 and 700 nm and the half-value width in the absorption spectrum of a dilute solution standardized to an absorbance of 1.0 is 100 nm or more. An object of the present invention is to provide an inkjet recording ink ensuring excellent discharge stability even after aging of the ink and also exhibiting excellent weather resistance.

Abstract: To provide inks and ink sets for inkjet recording, which have good fastness and good jet-out stability and which give good images with no bleeding trouble, yellow ink, black ink and magenta ink for inkjet printing contain at least two dyes each having an oxidation potential over 1.0 V (vs SCE).

Abstract: An ink for ink jet recording having a phthalocyanine dye dissolved and/or dispersed in an aqueous medium, characterized in that the aforementioned phthalocyanine dye is a water-soluble dye having an oxidation potential of more positive than 1.0 and the conductivity of the aforementioned ink is from not 0.01 S/m to not greater than 10 S/m. A process for the production of the aforementioned ink for ink jet recording which includes a step of applying ultrasonic vibration and/or a step of filtering using a filter having pores of an effective diameter of not greater than 1 ?m and defoaming the ink and an ink jet recording process using these inks. In accordance with such a constitution, an ink for ink jet recording and an ink jet recording process can be provided which exhibit a high ejection stability, give an image having an excellent hue and preservability (weathering resistance, water resistance) and provide an image with a high quality.

Abstract: An inkjet recording ink composition comprising an aqueous medium having dissolved and/or dispersed therein at least one dye, wherein at least one betaine-type surfactant is contained in the ink composition. The dye is preferably a magenta dye having an azo structure or a cyanine dye having a phthalocyanine structure. The inkjet recording ink composition is excellent in ejection property, light fastness, heat fastness and oxidation resistance and causing less dye bleeding.

Abstract: An inkjet recording ink including an aqueous medium having dissolved or dispersed therein a magenta dye selected from azo dyes, wherein the magenta dye is a dye having an oxidation potential more positive than 1.0 V (vs SCE) and at the same time, a water-miscible organic solvent having a vapor pressure of 2,000 Pa or less at 20° C. is contained; and an inkjet recording method using the ink. By virtue of such a constitution, an inkjet recording ink and an inkjet recording method are provided, which can ensure high ejection stability, good color hue of the obtained image, no drying of the ink at the ink jet head, excellent fastness to light and water, image quality free from defective such as fineline bleeding under high-humidity condition, and good preservability of the image under severe conditions, and furthermore can ensure high storability and high ejection stability even after aging for a long time or under severe conditions.

Abstract: An ink-jet ink containing a colorless, water-soluble, planar compound having more than ten delocalized pi-electrons per molecule.

Abstract: An ink set where constituent inks all are an ink containing at least one dye having an oxidation potential more positive than 1.0 V (vs SCE), particularly where the ratio k1/k2 of the fading rate constant (k1) of an image drawn by using the ink alone to the fading rate constant (k2) of a mixed color image drawn by using all constituent inks constituting the ink set in equivalent amounts with the same density measurement light as in the measurement of k1 is 0.7 to 1.3 in all inks. According the present invention, an inkjet ink set capable of giving an image having good image quality and excellent image fastness regardless of the color of image, such as aging stability, light fastness and water resistance, and an inkjet image recording method using the ink set are provided.

Abstract: An ink obtained by dissolving at least one specific dye in an aqueous medium, wherein the dyes contained in the ink all have a solubility of 15 g or more in 100 g of water at 25° C. under atmospheric pressure; and an ink set formed from the ink. The dye is preferably a dye having an oxidation potential of 1.0 V (vs SCE) or more, more preferably a specific azo dye having a heterocyclic group of a specific structure or an aromatic group which is bound directly to an azo group, or a specific phthalocyanine dye having a water-soluble group as a substitunet. According to the present invention, an ink, specifically an inkjet ink, and an ink set, which can print an image without disorder or beading due to ejection failure and ensure excellent ejection stability and durability, is provided.

Abstract: An inkjet recording ink set comprising at least two inks, wherein each of the inks contains at least one dye having an anionic group, and even when any two inks in the ink set are mixed, precipitation of the dye does not occur.

Abstract: As an ink for ink jet, containing at least a water-soluble dye having an anionic dissociable group, water and a water-soluble organic solvent, an ink including a cationic polymer capable of forming an ion pair with the anionic dissociable group is used. The cationic polymer is a water-soluble polymer, and at least one of cations is preferably derived from a nitrogen atom, and it is preferable to mix the cationic polymer and the water-soluble dye having the anionic desociable group in advance in water and to prepare an ink after eliminating the resulting salt.

Abstract: An inkjet recording ink of giving an image having high image quality and excellent weather resistance is provided, which is an inkjet recording ink comprising a specific phthalocyanine dye, wherein the total amount of cations in the ink except for a lithium ion, a hydrogen ion, an ammonium ion, an organic quaternary nitrogen ion and an ion produced by the proton addition to a nitrogen atom in a basic organic material is 0.5 wt % or less.

Abstract: An ink for inkjet comprising: a dye; and water and/or a water-miscible organic solvent, wherein the dye comprises a dye compound having at least one heterocyclic structure, and the ink further comprises, as an additive, at least one compound capable of chemically interacting with the dye compound.

Abstract: Provided are an inkjet ink prepared by dissolving or dispersing a specific dye in an aqueous medium and containing one of at least one alkylene diol where one alkylene group has at least 3 carbon atoms or homologue thereof and at least one polymer compound; and an ink set containing an ink including a specific dye and an ink including one compound capable of interacting with the dye; thereby being able to provide an ink and the like having a good jet-out stability, and forming images of good quality with neither beading nor bronzing, and the images formed of the inks have good fastness to heat, light and ozone.

Abstract: To provide an inkjet black ink having excellent image durability and ink discharge properties and an ink set, the inkjet black ink, which contains a dye having a ?max of from 500 nm to 700 nm and a half-band width of 100 nm or more in an absorption spectrum of a diluted solution standardized at an absorbance of 1.0 at the ?max, has the change ratio of absorbance at the ?max in the visible region, specified in the specification; and the inkjet ink set containing at least two black inks having different densities has the relationship among the at least two black inks, specified in the specification.

Abstract: The invention provides an inkjet black ink ensuring excellent image durability capable of satisfactorily maintaining the image quality such as non-loosening of black and gradation even when the image is stored for a long period of time, which is a inkjet black ink having a discoloration rate constant (kvis) of 5.0×10?2 [hour?1] or less, which is measured by using an ozone gas, the ink comprising an aqueous medium having dissolved or dispersed therein at least one dye selected from (1) an azo dye having a specific structure where a heterocyclic group is bonded to both of two N atoms, (2) a phthalocyanine dye having a specific structure, (3) an azo dye having a specific structure where a 5-membered heterocyclic group is bonded to one of two N atoms and a 6-membered 2-amino heterocyclic group is bonded to the other, and (4) a bisazo dye constituted by a specific aromatic or heterocyclic group and an azo group.

Abstract: An ink set comprising: at least two kinds of inks, each of the at least two kinds of inks having a common hue and different densities, and containing an aqueous medium and a dye, wherein each of the at least two kinds of inks has a corresponding discoloration velocity constant (k) for an image printed with each one of the at least two kinds of inks, and a ratio defined by a minimum value (kmin) selected from among said corresponding constants divided by a maximum value (kmax) selected from among the corresponding constants, is within a range of 0.7 to 1.0.

Abstract: An ink for ink jet recording including a magenta dye selected from azo dyes dissolved or dispersed in an aqueous medium, characterized in that said magenta dye is a dye having an absorption maximum in a spectral range of from 500 to 580 nm in said aqueous medium and a more positive oxidation potential than 1.0V (vs SCE), particularly with the aforesaid ink for ink jet recording wherein the azo dye has a specific structure having a 5-membered heterocyclic ring and a 4-amino-6-membered heterocyclic ring connected to the azo group.