Abstract: A water base ink for ink-jet recording is provided, which makes it possible to secure a high recording quality with a sharp image area edge by avoiding any blurring even when recording is performed on regular paper and which has satisfactory purge restoration performance. Therefore, no bubble remains in an ink flow passage, and no discharge failure is caused. Further, the discharge operation never becomes unstable. In the water base ink for ink-jet recording, the surface tension is not less than 40 mN/m, and the amount of dissolved oxygen is not more than 4 mg/L.

Abstract: A fluorescent water base ink for ink-jet recording contains a fluorescent dye having a xanthene skeleton, and a glycol. In the fluorescent dye, the difference in hydrophilic index log P is not less than 2.6 between a substituent bonded to C-9 carbon atom of the xanthene skeleton and other portion of the fluorescent dye than the substituent bonded to the C-9 carbon atom. The glycol has a distance between hydroxyl groups substantially equivalent to or longer than an interatomic distance between atoms directly bonded to C-3 and C-6 carbon atoms of the xanthene skeleton of the fluorescent dye, respectively. It is assumed that the glycol is coordinated with the xanthene skeleton in a bridge form to increase the fluorescence intensity by increasing the electron density of the xanthene skeleton. The ink having high fluorescence intensity and in which the fluorescence intensity is not lowered in a time-dependent manner is provided.

Abstract: A fluorescent water base ink for ink-jet recording to be used for an ink-jet printer contains water, a pigment, a compound having primary or secondary amide group, and a fluorescent dye represented by the following formula (1): wherein R1 represents OH or N(R3)R4, R2 represents hydrogen atom or halogen atom, and each of R3 and R4 represents hydrogen atom or alkyl group. A sufficient OD value and a fluorescence value are obtained while securing the vivid color development and the excellent water resistance principally in accordance with the interaction of the fluorescent dye and the compound having the amide group.

Abstract: A water base ink for ink-jet recording is provided, which makes it possible to secure a high recording quality with a sharp image area edge by avoiding any blurring even when recording is performed on regular paper and which has satisfactory purge restoration performance. Therefore, no bubble remains in an ink flow passage, and no discharge failure is caused. Further, the discharge operation never becomes unstable. In the water base ink for ink-jet recording, the surface tension is not less than 40 mN/m, and the amount of dissolved oxygen is not more than 4 mg/L.

Abstract: A water base ink for ink-jet recording contains a surfactant represented by the following formula (1) or (2), dipropylene glycol, a coloring agent, and water: CH3—(CH2)11—O—(CH2CH2O)z—H(2) In the formula (1), R represents alkyl group, and x and y represent integers which satisfy x+y=5 to 15. In the formula (2), z represents an integer of not more than 9. The performance of initial introduction into a recording head is satisfactory, and it is possible to simultaneously reduce the feathering and the color bleed even when the recording is performed on regular paper.

Abstract: A fluorescent water base ink for ink-jet recording includes water, a first fluorescent dye, and a second fluorescent dye. The first fluorescent dye absorbs light in a first absorption wavelength region in an ultraviolet region to emit fluorescence, and the first fluorescent dye absorbs light in a second absorption wavelength region to emit no fluorescence. The second fluorescent dye absorbs light in an absorption wavelength region in the ultraviolet region, which is different from the first absorption wavelength region of the first fluorescent dye, to emit fluorescence. A wavelength region of the fluorescence of the second fluorescent dye is not overlapped with the first absorption wavelength region of the first fluorescent dye, but at least a part of the wavelength region of the fluorescence of the second fluorescent dye is overlapped with the second absorption wavelength region. The fluorescence intensity of the ink is increased.

Abstract: A water base ink for ink-jet recording contains an amine compound selected from the group consisting of N-n-butylethanolamine, 1,4-bis(3-aminopropyl)piperazine, benzylamine, and an amine compound represented by a specified structural formula, a surfactant having a specified structural formula, a coloring agent, and water. It is possible to obtain a satisfactory rub resistance and a high printing quality with a sharp outline without causing any feathering on a recorded image. Further, it is possible to obtain a long term nozzle discharge stability by suppressing any corrosion on a metal member of a discharge head unit of an ink-jet recording apparatus.

Abstract: A fluorescent water base ink for ink-jet recording contains a fluorescent dye having a xanthene skeleton, and a glycol. In the fluorescent dye, the difference in hydrophilic index log P is not less than 2.6 between a substituent bonded to C-9 carbon atom of the xanthene skeleton and other portion of the fluorescent dye than the substituent bonded to the C-9 carbon atom. The glycol has a distance between hydroxyl groups substantially equivalent to or longer than an interatomic distance between atoms directly bonded to C-3 and C-6 carbon atoms of the xanthene skeleton of the fluorescent dye, respectively. It is assumed that the glycol is coordinated with the xanthene skeleton in a bridge form to increase the fluorescence intensity by increasing the electron density of the xanthene skeleton. The ink having high fluorescence intensity and in which the fluorescence intensity is not lowered in a time-dependent manner is provided.

Abstract: A fluorescent water base ink for ink-jet recording contains a first fluorescent dye and a second fluorescent dye. The first fluorescent dye has a first ultraviolet absorption wavelength region in an absorption spectrum and a first fluorescence emission wavelength region in a fluorescence spectrum. The second fluorescent dye has a second ultraviolet absorption wavelength region which is different from the first ultraviolet absorption wavelength region in an absorption spectrum and a second fluorescence emission wavelength region in a fluorescence spectrum. The first fluorescent dye further has an absorption wavelength region which is different from the first ultraviolet absorption wavelength region and which overlaps at least a part of the second fluorescence emission wavelength region.

Abstract: Fluorescent water base ink for ink-jet recording contains water, a fluorescent dye having a skeleton for emitting fluorescence, and a polyol having not less than two hydroxyl groups. A distance between oxygen and oxygen of the two hydroxyl groups in the polyol is substantially equal to or longer than a length of the skeleton of the fluorescent dye. When the fluorescent dye has a xanthene skeleton, 1,5-pentanediol can be used as the polyol. The ink has the high fluorescence intensity.

Abstract: A fluorescent water base ink for ink-jet recording to be used for an ink-jet printer contains water, a pigment, a compound having primary or secondary amide group, and a fluorescent dye represented by the following formula (1): wherein R1 represents OH or N(R3)R4, R2 represents hydrogen atom or halogen atom, and each of R3 and R4 represents hydrogen atom or alkyl group. A sufficient OD value and a fluorescence value are obtained while securing the vivid color development and the excellent water resistance principally in accordance with the interaction of the fluorescent dye and the compound having the amide group.

Abstract: A water base ink set for ink-jet recording comprises a black ink which contains a black pigment, water, and a water-soluble organic solvent, and a color ink which contains a dye, water, a water-soluble organic solvent, and at least one compound represented by the following formulas (1) to (3), wherein the nozzle clog-up at an ink-jet head and the malfunction of a purging pump, which would be otherwise caused by the aggregation of the black ink, can be avoided: R1—O—(CH2CH2O)x—SO3.Na??(1) wherein R1 represents a straight chain alkyl group having a number of carbon atoms of 16 to 22, and x=20 to 30 is satisfied in the formula (1); wherein l+m+n+o+p+q=20 to 100 is satisfied in the formula (2); and wherein R2 represents a straight chain alkyl group having a number of carbon atoms of 16 to 22, and y=100 to 300 is satisfied in the formula (3).

Abstract: A water base ink for ink-jet recording, which is usable for an ink-jet recording apparatus having an ink-jet head provided therein with an ink flow passage formed of nickel or nickel alloy, includes a coloring agent, water, and a water-soluble organic solvent. The ink is blended so that a current density, which is obtained within an electric potential range of −600 to +300 mV, is not more than 100 &mgr;A/cm2 when anodic polarization measurement is performed by using a reference electrode of silver/silver chloride, a counter electrode of platinum, and a working electrode of nickel or nickel alloy. The ink does not corrode any part for constituting the flow passage in the ink-jet head.

Abstract: A water base ink for ink-jet recording is provided, which makes it possible to secure a high recording quality with a sharp image area edge by avoiding any blurring even when recording is performed on regular paper and which has satisfactory purge restoration performance. Therefore, no bubble remains in an ink flow passage, and no discharge failure is caused. Further, the discharge operation never becomes unstable. In the water base ink for ink-jet recording, the surface tension is not less than 40 mN/m, and the amount of dissolved oxygen is not more than 4 mg/L.

Abstract: An ink for ink-jet recording of the present invention includes water and a pigment. A total amount of free monovalent metal is not more than 300 ppm in the ink, and a total amount of free divalent or polyvalent metal is not more than 5 ppm in the ink. The ink may further comprise an antiseptic/fungicidal agent. The ink is excellent in dispersion stability of the pigment. The ink is stably discharged from a head over a long period without causing any clog-up at an ink flow passage and a nozzle of the head of a recording apparatus.

Abstract: A water base ink for ink-jet recording, which is usable for an ink-jet recording apparatus having an ink-jet head provided therein with an ink flow passage formed of nickel or nickel alloy, comprises a coloring agent, water, and a water-soluble organic solvent. The ink is blended so that a current density, which is obtained within an electric potential range of −600 to +300 mV, is not more than 100 &mgr;A/cm2 when anodic polarization measurement is performed by using a reference electrode of silver/silver chloride, a counter electrode of platinum, and a working electrode of nickel or nickel alloy. The ink does not corrode any part for constituting the flow passage in the ink-jet head.

Abstract: A water base ink set for ink-jet recording comprises a black ink which contains a black pigment, water, and a water-soluble organic solvent, and a color ink which contains a dye, water, a water-soluble organic solvent, and at least one compound represented by the following formulas (1) to (3), wherein the nozzle clog-up at an ink-jet head and the malfunction of a purging pump, which would be otherwise caused by the aggregation of the black ink, can be avoided:

Abstract: A water base ink for ink-jet recording contains a surfactant represented by the following formula (1) or (2), dipropylene glycol, a coloring agent, and water: 1

Abstract: A water base ink for ink-jet recording contains an amine compound selected from the group consisting of N-n-butylethanolamine, 1,4-bis(3-aminopropyl)piperazine, benzylamine, and an amine compound represented by a specified structural formula, a surfactant having a specified structural formula, a coloring agent, and water. It is possible to obtain a satisfactory rub resistance and a high printing quality with a sharp outline without causing any feathering on a recorded image. Further, it is possible to obtain a long term nozzle discharge stability by suppressing any corrosion on a metal member of a discharge head unit of an ink-jet recording apparatus.

Abstract: An ink for ink-jet recording of the present invention comprises water and a pigment. A total amount of free monovalent metal is not more than 300 ppm in the ink, and a total amount of free divalent or polyvalent metal is not more than 5 ppm in the ink. The ink may further comprise an antiseptic/fungicidal agent. The ink is excellent in dispersion stability of the pigment. The ink is stably discharged from a head over a long period without causing any clog-up at an ink flow passage and a nozzle of the head of a recording apparatus.