Abstract: Provided is magenta ink that satisfies all the necessary properties including good light-fastness, good color reproducibility, especially good color reproducibility of magenta-related secondary colors of red and blue, and high reliability, and gives satisfactory high-quality images. Also provided are a color ink set for ink-jet recording, which contains the magenta ink, and an ink-jet recording method in which is used the magenta ink or the color ink set. The magenta ink contains water, a colorant and at least two water-soluble organic solvents, and its visible-light absorbance spectrum gives a first peak A (abs.) within a range of from 500 to 570 nm and a second peak B (abs.) within a range of from 300 to 350 nm with a ratio A/B falling between 0.9 and 2.5. The magenta ink is combined with cyan ink and yellow ink to form the color ink set, which contains water, colorants and at least two water-soluble organic solvents.

Abstract: Disclosed is an ink holding material to be put in an ink tank of an ink jet recording device, which is such that when it is extracted with pure water, the electrical conductivities and the surface tensions of the water before and after the extraction satisfy relationship (1):350 .gtoreq..gamma.r/.sigma.r-.gamma.s/.sigma.s.gtoreq.0 (1)wherein .gamma.r represents the surface tension (mN/m) of pure water before extraction; .sigma.r represents the electrical conductivity (mS/m) of pure water before extraction; .gamma.s represents the surface tension (mN/m) of pure water after extraction; and .sigma.s represents the electrical conductivity (mS/m) of pure water after extraction.

Abstract: An ink jet recording ink including water, a water-soluble organic solvent, and at least one dye having at least one carboxyl group in the form of a free acid, wherein at least one compound selected form secondary or tertiary amine compounds represented by the following general formula (I) and at least one compound selected from the alkali metal hydroxides are contained and the pH value thereof is from 8.5 to 12: ##STR1## wherein one or two of R.sup.1, R.sup.2, and R.sup.3 are an alkyl group having 1 to 5 carbon atoms in the alkyl chain and substituted by a substituent selected from a carboxyl group, a sulfonic group, an alkali metal salt of a carboxyl group, and an alkali metal salt of a sulfonic group; and the remainder is a group selected from a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a substituted alkyl group having 1 to 5 carbon atoms in the alkyl chain and substituted by a hydroxyl group or carbamoyl group is disclosed.

Abstract: An ink jet recording ink comprising: (i) water, (ii) a water-soluble organic solvent, (iii) at least one dye having at least one carboxyl group in the form of a free acid, (iv) a substituted aromatic compound represented by general formula (I); and (v) at least one alkali metal hydroxide, wherein the pH value of the ink is from 8 to 12, and an ink jet recording method in which such ink droplets are discharged from an orifice according to a recording signal to record an image using this ink jet recording ink are disclosed, general formula (I) being: ##STR1##

Abstract: Disclosed is a color ink set for ink-jet recording, which color ink set comprises a set of single-color ink, namely, cyan ink, magenta ink, yellow ink and black ink, each single-color ink containing at least a colorant, a water-soluble organic solvent and water, wherein the colorant in the single-color ink has a specific chemical structure, and which color ink set for ink-jet recording fulfills the characteristics required for ink-jet recording ink, along with the details of single-color ink constituting the ink set and an ink-jet recording method using the color ink set.

Abstract: An ink for ink jet recording, which comprises water, a water-soluble dye and a water-soluble organic solvent, wherein said ink contains potassium ion in an amount of from not less than 450 ppm to not more than 10,000 ppm, and said water-soluble organic solvent comprises glycerin in an amount of from 5 to 20% by weight based on the total weight of said ink.

Abstract: An ink-jet ink contains water, a coloring material and an amine compound represented by the formula: R.sub.1 R.sub.2 R.sub.3 N (I) wherein one or two of R.sub.1, R.sub.2 and R.sub.3 represent(s) (an) alkyl group(s) having 1 to 5 carbon atoms substituted by at least one group selected from the group consisting of a carboxy group, a sulfonic acid group, and a Li, Na, Na, K or ammonium salt thereof, and the remainder represents(s) (an) hydrogen atom(s) or (an) alkyl group(s) having 1 to 5 carbon atoms substituted by a hydroxide group or a carbamoyl group. The pH value of the ink is preferably between 6 to 8. Moreover, printing may be made by applying thermal energy to the ink and forming droplets.The ink and the method of printing using the ink may prevent the change of the amount of ink droplets due to kogation on a heater even with a long-term use, and may not cause a heater trouble due to the corrosion of materials constantly in contact with ink.

Abstract: Ink-jet recording ink comprising water, a water-soluble organic solvent and a color material as essential ingredients, wherein the total volume of particulate matter ranges from 1.times.10.sup.-9 to 1.times.10.sup.-2 cm.sup.3 per cm.sup.3 of ink, whereby defects in images such as blank areas on images, fluctuations in dot diameter and the disturbed shape of dots are not generated to give a prominent effect and wherein the total volume of the particulate matter existing in 1 cm.sup.3 of the ink is adjusted to 3.5.times.10.sup.-6 or less, whereby ink which is stable even after long-term use can be obtained and change in amount of ink at jetting is slight, as well as defects in images can be prevented.

Abstract: An ink for inkjet printers comprises water, a water-soluble organic solvent, and a colorant. The ink further comprises an amine having at least one substituent selected from the group consisting of a sulfonic acid group, a carboxylic acid group and a halogen atom, so that the variation in pH of the ink can be suppressed to a minimum. The pH of the ink is preferably in the range of from 5 to 9.

Abstract: An ink for ink jet recording contains a dye and water, a water soluble organic solvent which dissolves the dye, and 0.8 to 5 weight percent of propylene oxide/ethylene oxide block copolymer which has an average molecular weight from 1000 to 5000 and whose content of ethylene oxide group is in the range from 5 to 60 weight percent based on the average molecular weight of the block copolymer. The ink has a surface tension of 30-40 dyne/cm and a viscosity of 1-10 centipoise. An ink jet ink of this invention can be a combination of three colors, e.g., cyan, magenta and yellow, or four colors (adding black to these colors).

Abstract: An novel ink for thermal ink jet recording comprising at least water and a coloring material is provided, characterized in that there is contained an amino compound represented by the following general formula (I) or (II): ##STR1## wherein R.sub.1 represents a C.sub.1-5 alkyl group having a hydroxyl group; R.sub.2, R.sub.7 and R.sub.8 may be the same or different and each represents a hydrogen atom or a C.sub.1-5 alkyl group having a hydroxyl group; R.sub.3, R.sub.4 and R.sub.5 may be the same or different and each represents a C.sub.1-3 alkylene group; and R.sub.6 represents a C.sub.1-5 alkylene group. The content of said amino compound is in the range of 0.005 to 5.0% by weight.