Abstract: There are provided a carbon black according to which long-term stable storage is possible, clogging is not prone to occurring, and the OD value is high and hence printing with a deep black color is possible, or a carbon black that can be used in a water-based ink that is used in ink jet printer printing, that has low settleability and can thus be stored stably for a long period, for which clogging is not prone to occurring, and for which the reflection density is high and hence printing with a high printing density and a deep black color is possible, a carbon black dispersion having the carbon black dispersed therein, and a water-based ink containing the carbon black.

Abstract: The present invention provides a water-based ink that is used in ink jet printer printing, with a writing instrument, or the like, that has a low settling rate and for which clogging is not prone to occurring, that can be stored stably for a long period without the viscosity or the carbon black particle diameter increasing, and for which printing with a deep black color and a high print density is possible, and a modified carbon black dispersion used for preparing this water-based ink. The present invention is a liquid having dispersed therein a modified carbon black obtained by subjecting a carbon black raw material powder to oxidation treatment, wherein the modified carbon black has on the surface thereof (a) carboxyl groups, and (b) lactone groups in a molar amount of at least 500 ?mol/g relative to the weight of the modified carbon black and a molar ratio of 0.8 to 1.1 times the amount of the carboxyl groups.

Abstract: The present invention provides a water-based ink that is used in ink jet printer printing, with a writing instrument, or the like, that has a low settling rate and for which clogging is not prone to occurring, that can be stored stably for a long period without the viscosity or the carbon black particle diameter increasing, and for which printing with a deep black color and a high print density is possible, and a modified carbon black dispersion used for preparing this water-based ink. The present invention is a liquid having dispersed therein a modified carbon black obtained by subjecting a carbon black raw material powder to oxidation treatment, wherein the modified carbon black has on the surface thereof (a) carboxyl groups, and (b) lactone groups in a molar amount of at least 500 ?mol/g relative to the weight of the modified carbon black and a molar ratio of 0.8 to 1.1 times the amount of the carboxyl groups.

Abstract: There are provided a carbon black according to which long-term stable storage is possible, clogging is not prone to occurring, and the OD value is high and hence printing with a deep black color is possible, or a carbon black that can be used in a water-based ink that is used in ink jet printer printing, that has low settleability and can thus be stored stably for a long period, for which clogging is not prone to occurring, and for which the reflection density is high and hence printing with a high printing density and a deep black color is possible, a carbon black dispersion having the carbon black dispersed therein, and a water-based ink containing the carbon black.

Abstract: It is provided an aqueous pigment dispersion having improved dispersing stability in which carbon black shows appropriate initial dispersing property and long-term dispersing property to water, and carbon black particles are less susceptible to aggregation. Moreover, it is provided a raw material for ink-jet ink having improved printing density when alkali metal cation is substituted by potassium ion. The present invention is summarized as an aqueous pigment dispersion, which contains surface modified carbon black that is obtained by wet-oxidizing carbon black by using hypohalous acid and/or a salt thereof, and alkali metal cation, characterized in that concentration of the alkali metal cation is not more than 2% by weight.

Abstract: Disclosed is an aqueous pigment ink composition comprising at least water and carbon black, wherein a surface oxygen content of said carbon black is not less than 0.07 in atom-numeral ratio based on carbon atom measured by an X-ray photoelectron spectroscopic method, and a combined value of a surface carboxyl group carbon content and a surface hydroxyl group carbon content of said carbon black, the both being measured by an X-ray photoelectron spectroscopic method, is not less than 0.5%. The aqueous pigment ink composition realizes smooth printing with an ink jet nozzle, and smooth writing with a fine pen tip and it has sufficient density. Further, the recorded traces obtained by using the ink composition is excellent in water resistance.

Abstract: The present invention provides an aqueous black ink composition for a writing board which hardly causes thickening, coagulation of the pigment, decreasing of writing density due to sedimentation, clogging in a penpoint, and break in writing. The aqueous black ink composition comprises water, the oxidized carbon black obtained by oxidizing carbon black using hypohalogenous acid and/or salt thereof, a film forming agent, and a release agent.

Abstract: An aqueous pigment ink composition comprising an oxidized carbon black obtained by wet-oxidation of a carbon black using a hypohalous acid and/or salt thereof, and a water-soluble cationic polymer or oligomer in an aqueous medium. The aqueous pigment ink composition of the present invention does not cause clogging in a nozzle when used for ink jet recording, enables smooth writing from a narrow pen tip, and provides a recorded image excellent in water resistance and light resistance and excellent in density and hue.

Abstract: Disclosed is an aqueous pigment ink composition comprising water and oxidized carbon black dispersed stably in the water, wherein said oxidized carbon black is obtained by oxidizing carbon black using hypohalous acid and/or salt thereof and wherein at least a part of an acidic group existing on the surface of said oxidized carbon black associates with an amine compound to form an ammonium salt. The aqueous pigment ink composition realizes smooth printing with ink jet nozzle, and smooth writing with fine pen tip and it has sufficient density. Further, the recorded traces obtained by using the ink composition is excellent in water resistance.

Abstract: The present invention provides a process for producing aqueous pigment ink which forms a black matrix having high optical density, excellent flatness of a film and low conductivity, and imparts high resolution power to a color filter. The process comprises the steps of:finely dispersing a carbon black having an oil absorptivity of not more than 100 ml/100 g in an aqueous medium; andoxidizing the carbon black by using a hypohalite.