JP2013060563A - Inkjet recording ink, cartridge, inkjet recording apparatus, image forming method, and image-recorded matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an inkjet recording ink that has storage stability of the ink and can achieve high image density even on both a smooth paper and a non-smooth paper; a cartridge having the ink stored therein; an inkjet recording apparatus having the cartridge mounted thereon; and an image forming method and an image-recorded matter using the ink.SOLUTION: The inkjet recording ink contains water, a pigment dispersion having pH controlled to 6 to 8, and a penetrant. The pigment is a carbon black in which a carbon black having a BET specific surface area of 90 to 150 m/g is subjected to ozone oxidation to have volatile content of 10 to 20%.

Description

  The present invention relates to an ink for ink jet recording, a cartridge containing the ink in a container, an ink jet recording apparatus equipped with the cartridge, an image forming method using the ink, and an image formed article.

In recent years, as an image forming method, since the process is simple and full color can be easily obtained as compared with other recording methods, there is an advantage that a high-resolution image can be obtained even with an apparatus having a simple configuration. The method has become widespread.
Inkjet recording is a method in which a small amount of ink is ejected by bubbles generated by heat, pressure generated by using piezoelectricity or static electricity, and is adhered to a recording medium such as paper and dried quickly (or recording). This is a method of forming an image (by penetrating into a medium), and its application has been expanded to personal and industrial printers and printing.
In recent years, demand for industrial applications has been increasing, and compatibility with various recording media such as high-speed printing and paper is desired. In addition, inkjet printers equipped with line heads have become necessary as the speed increases. In addition, there is a growing demand for water-based inks from the environmental and safety aspects. However, water-based inks are easily affected by the recording medium and cause various problems in the image. In particular, when non-smooth paper is used as a recording medium, the occurrence of problems is remarkable. In the case of water-based ink, it takes time to dry and the compatibility with paper is good, so it has high permeability to paper, especially in the case of uncoated and relatively non-smooth paper, the coloring material penetrates into the paper. As a result, the color density of the formed color material becomes low, which is a problem not seen with solvent inks.
In particular, as high-speed printing progresses, means for increasing the drying speed by adding a penetrant to the ink and allowing water as a solvent to permeate the recording medium is taken in order to increase the drying speed of the ink attached to the recording medium. However, when a penetrating agent is contained, the permeability of not only water but also a color material into the recording medium becomes high. Further, unlike the ink used for paints and ballpoint pens, there is a significant problem that the image density is lowered.

As a method for improving the printed image density, Patent Document 1 proposes a method in which acidic carbon black is oxidized with hypochlorous acid to control the ratio of surface functional group amount / specific surface area of carbon black. However, since the treatment with hypochlorite uses water as a solvent, dehydration and washing are necessary and the cost is high, and salt and the like remain in the washing. The shelf life was not satisfactory. In the case of non-smooth paper, the image density was not satisfactory.
Patent Document 2 proposes to define the surface functional group amount and specific surface area of carbon black for the purpose of improving dispersion stability. However, wet oxidation using peroxodisulfate or the like is performed, and for the same reason as in Patent Document 1, storage stability and image density are not satisfactory.
Patent Document 3 proposes the use of furnace carbon black in which the DBP oil absorption and acidic groups are defined. However, in order to obtain the specified DBP absorption amount with furnace carbon black, it is necessary to use one having a large specific surface area, and even if acid groups are increased by oxidation, it is effective to exist on the actual carbon black surface. There are few acidic groups, and it is not satisfactory in terms of storage stability and image density when used in ink.
Patent Document 4 proposes the use of carbon black in which the volatile content of carbon black treated by oxidation is specified to be 25% or more. However, if the volatile content is high, the water dispersibility improves, but the stability decreases due to an increase in impurities during oxidation, the water compatibility becomes too high, and the pigment soaks into the paper together with the water. This makes it difficult to obtain a sufficient image density.
Patent Document 5 proposes the use of carbon black with volatile content and CTAB surface area / iodine value defined. However, it is difficult to satisfy both the image density and the storage stability sufficiently only by satisfying the above requirements.

  The present invention has been made in view of the above-described prior art, and has good ink storage stability and can achieve high image density on both smooth paper and non-smooth paper. It is an object of the present invention to provide an accommodated cartridge, an ink jet recording apparatus equipped with the cartridge, an image forming method using the ink, and an image formed product.

The above problems are solved by the following inventions 1) to 5).
1) Water, containing a pigment dispersion adjusted to pH 6 to 8 and a penetrant, and the pigment is ozone-oxidized carbon black having a BET specific surface area of 90 to 150 m ² / g to reduce volatile content to 10 An ink for ink-jet recording, characterized by being 20% carbon black.
2) A cartridge in which the ink for ink jet recording described in 1) is contained in a container.
3) An ink jet recording apparatus comprising the cartridge described in 2).
4) An image forming method using the ink for ink jet recording described in 1) and forming an image using an ink jet recording apparatus provided with an ink discharge head.
5) An image formed product printed using the ink for ink jet recording described in 1).

  According to the present invention, ink for ink-jet recording, which has good ink storage stability and can achieve high image density on both smooth paper and non-smooth paper, a cartridge containing the ink in a container, and an ink jet equipped with the cartridge A recording apparatus, an image forming method using the ink, and an image formed product can be provided.

It is a figure which shows an example of the inkjet recording device of this invention. It is a figure which shows an example of an inkjet recording head. It is a figure which shows another example of an inkjet recording head. It is an external appearance perspective view which shows an example of the cartridge of this invention. It is a front sectional view of an example of the cartridge of the present invention.

Hereinafter, the present invention will be described in detail.
In the inkjet recording ink of the present invention (hereinafter sometimes referred to as ink), carbon black having a BET specific surface area of 90 to 150 m ² / g is oxidized by ozone treatment to adjust the volatile content to 10 to 20%. Is used. The ozone treatment method is not particularly limited, but a dry method in which ozone gas is circulated through carbon black is preferable because of its high oxidation treatment ability. In the treatment using water, a reaction between water and ozone occurs, so that sufficient oxidation may not be possible. Ozone is obtained by passing air or oxygen through an ozone generator.
The adjustment of the volatile matter can be controlled by adjusting the amount of ozone and the treatment time. If the amount of ozone (concentration) is increased or the treatment time is lengthened, carbon black having a large amount of volatile matter can be obtained. Although the processing time and the volatile content are in a proportional relationship, saturation is reached after a certain time (the volatile content does not increase). Therefore, it is necessary to adjust while confirming the volatile content. In addition, the above conditions vary depending on the characteristics of carbon black before oxidation treatment, impurities, and the like, and may be adjusted as appropriate.

The raw material carbon black may have a BET specific surface area of 90 to 150 m ² / g, but an oil absorption amount (DIN ISO 787/5 method) of 230 g / 100 or more is preferable in terms of image density. Various carbon blacks such as furnace black, lamp black, acetylene black, and gas black can be used, but gas black is preferable in terms of image density.
In addition, the volatile matter in this invention is a value by the measuring method of DIN 53 552, and a BET specific surface area is a value by the measuring method of DIN 66132.
In addition to the above-mentioned ozone-treated carbon black, carbon black that has been oxidized or alkali-treated on the surface, or carbon black that has been coated with resin or grafted or encapsulated can be used together. Those that are not treated with a resin coating or the like are preferable.
The primary particle size of carbon black used in combination is 10 to 50 nm, the BET specific surface area is 50 to 400 m ² / g, the DBP absorption is 40 to 500 mL / 100 g, the volatile content is 0.5 to 20%, and the pH is 2 to 9. preferable.

The reason why the ink of the present invention can achieve both image density and storage stability is unknown, but is presumed as follows.
As a result of the study by the present inventors on the volatile matter of carbon black, when the volatile matter is increased, the carbon black stays on the paper surface and the image density tends to be improved. Although it can be seen from around 20%, it has been found that the image is saturated and sufficient image density cannot be obtained. Also, as the volatile content increases, the hydrophilicity of carbon black increases and the dispersibility improves, but it is also found that the stability of the ink deteriorates due to the increase in impurities due to oxidation, and the image density and the storage stability of the ink are reduced. I couldn't achieve both. Moreover, although the specific surface area and the ratio of the volatile matter were examined, they were not compatible.
Therefore, further investigations have been made. The oxidation method is ozone oxidation with less generation of impurities, the volatile content is kept at 10 to 20% where the image density effect does not yet appear, and the BET specific surface area is set at 90 to 150 m ² / g. By adjusting the storage stability and further adjusting the pH of the pigment dispersion to 6-8, the image density that was insufficient could be improved. The pH of the pigment dispersion is desirably adjusted before the dispersion, and when adjusted after the dispersion, it tends to be inferior in terms of dispersibility and storage stability. A metal hydroxide is preferably used for pH adjustment, and examples thereof include lithium hydroxide, sodium hydroxide, and potassium hydroxide.
The pigment concentration in the pigment dispersion is preferably 0.1 to 50% by weight, particularly preferably 0.1 to 30% by weight.
Further, when the pigment dispersion contains an ether type polyurethane resin having an acid value of 40 to 100, the storage stability can be further improved while maintaining the image density.

Moreover, you may use a dispersing agent for the pigment dispersion in the range which does not impair the effect of this invention.
Examples of the dispersant include various surfactants such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant, and a polymer type dispersant. These may be used alone or in combination of two or more.
Examples of the anionic surfactant include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acyl amino acids and salts thereof, N-acyl methyl taurate, polyoxyalkyl ether sulfates. Salt, polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester salt, lauryl alcohol sulfate ester salt, alkylphenol type phosphate ester, naphthalenesulfonate formalin condensate, alkyl type phosphate ester, alkylallylsulfone hydrochloride, diethyl Examples include sulfosuccinate, diethylhexyl sulfosuccinate, and dioctyl sulfosuccinate.
Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.

Examples of amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, imidazoline. Derivatives and the like.
Examples of nonionic surfactants include the following.
Ether-based interfaces such as polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyallylalkyl alkyl ether Active agent;
Polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate Ester surfactants such as
2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyn-3-ol Acetylene glycol surfactants such as

  The dispersion medium of the pigment dispersion desirably contains water, but various water-soluble organic solvents may be used in combination as necessary. Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, 1-propanol and 2-propanol, polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and glycerin, N-methylpyrrolidone, 2- Examples include pyrrolidone derivatives such as pyrrolidone, ketones such as acetone and methyl ethyl ketone, alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine.

A penetrant is blended in the ink of the present invention. A penetrant can also be added to the pigment dispersion.
The penetrant preferably contains at least one polyol compound having a solubility in water at 20 ° C. of 0.2 to 5.0% by weight. Examples of such a polyol compound include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, and 2,2-diethyl-1,3-propanediol. 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1,2- Examples thereof include aliphatic diols such as diol and 2-ethyl-1,3-hexanediol.
Among these, 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol are particularly preferable.
Other penetrants that can be used in combination are not particularly limited as long as they can be dissolved in the ink and adjusted to the desired physical properties, and can be appropriately selected according to the purpose. For example, diethylene glycol monophenyl ether, ethylene Examples thereof include alkyl and aryl ethers of polyhydric alcohols such as glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether and tetraethylene glycol chlorophenyl ether, and lower alcohols such as ethanol.
The content of the penetrant in the ink is preferably 0.1 to 4.0% by weight. If the amount is less than 0.1% by weight, quick-drying cannot be obtained and a blurred image may be obtained. If the amount exceeds 4.0% by weight, the dispersion stability of the colorant is impaired, and the nozzle is easily clogged. In addition, the permeability to the recording medium becomes higher than necessary, and the image density may be lowered or the image may be lost.

In addition to the pigment dispersion and penetrant, the ink of the present invention includes a water-soluble organic solvent, a resin, a wetting agent, a surfactant, a pH adjuster, an antiseptic / antifungal agent, a chelating reagent, and a rust inhibitor as necessary. Various known additives such as antioxidants, ultraviolet absorbers, oxygen absorbers, and light stabilizers can be blended. These additives may be blended in the pigment dispersion, but the surfactant blended in the ink is different in type and function from the surfactant blended in the pigment dispersion described above.
Examples of the water-soluble organic solvent are the same as those used as the dispersant for the pigment dispersion described above.
The wetting agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides , Amines, sulfur-containing compounds, propylene carbonate, ethylene carbonate, and other wetting agents. These may be used alone or in combination of two or more.

Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-butanediol, 3-methyl- 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, trimethylolethane, trimethylolpropane, glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1 2,6-hexanetriol, petriol, and the like.
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like. It is done.
Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone, and the like. Is mentioned.
Examples of amides include formamide, N-methylformamide, N, N-dimethylformamide, and the like.
Examples of amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol, and the like.

Other humectants are preferably sugars. Examples of saccharides include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and the like. Specific examples include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include a substance that exists widely in nature such as α-cyclodextrin and cellulose. Examples of derivatives of these saccharides include reducing sugars of the aforementioned saccharides (for example, sugar alcohols represented by the general formula: HOCH ₂ (CHOH) nCH ₂ OH (n = 2 to 5)), oxidized sugars ( For example, aldonic acid, uronic acid, etc.), amino acids, thioic acid and the like. Among these, sugar alcohols are preferable, and specific examples include maltitol and sorbit.
Among the above-mentioned wetting agents, glycerin, diethylene glycol, triethylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol, 2-pyrrolidone, N from the viewpoint of storage stability and ejection stability -Methyl-2-pyrrolidone is particularly preferred.

The blending ratio of the pigment and the wetting agent greatly affects the ink ejection stability from the head. If the blending amount of the wetting agent is small even though the pigment solid content is high, the evaporation of water near the ink meniscus of the nozzle may progress, resulting in ejection failure.
The content of the wetting agent in the ink is about 20 to 35% by weight, but more preferably 22.5 to 32.5% by weight. Within this range, the results of ink drying, storage test, reliability test and the like are very good. If the content is less than 20% by weight, the ink may easily dry on the nozzle surface, resulting in ejection failure. If the content exceeds 35% by weight, the dryness on the paper surface is poor and the character quality on plain paper is poor. May decrease.

As the surfactant, those having a low surface tension and a high leveling property are used, depending on the type of pigment and the combination with the wetting agent. For example, fluorine-based surfactants and silicone-based surfactants can be mentioned, and fluorine-based surfactants are preferable.
As the fluorine-based surfactant, those having 2 to 16 carbon atoms substituted with fluorine are preferable, and those having 4 to 16 carbon atoms are more preferable. If the number of carbon atoms substituted with fluorine is less than 2, the effect of fluorine may not be obtained, and if it exceeds 16, problems such as ink storage stability may occur.
Examples of fluorosurfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and perfluoroalkyl ether groups in the side chain. And polyoxyalkylene ether polymer compounds. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is particularly preferable because of its low foaming property.

Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.
Examples of the perfluoroalkyl carboxylic acid compound include perfluoroalkyl carboxylic acid and perfluoroalkyl carboxylate.
Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters, perfluoroalkyl phosphate salts, and the like.
The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain. And a salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain.

As counter ions of salts in these fluorosurfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ etc. are mentioned.
As a fluorine-type surfactant, what was synthesize | combined suitably may be used, or a commercial item may be used. Examples of commercially available products include DuPont FS-300, Neos FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW, and OM-nova PF-151N. Is mentioned.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. However, those which do not decompose even at high pH are preferable. For example, side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, piece Examples include terminal-modified polydimethylsiloxane and side-chain both-end-modified polydimethylsiloxane, and those having a polyoxyethylene group or polyoxyethylene polyoxypropylene group as a modifying group exhibit good properties as an aqueous surfactant. preferable.
As the silicone-based surfactant, an appropriately synthesized product or a commercially available product may be used. Commercial products are easily available from, for example, Big Chemie, Shin-Etsu Silicone, Toray Dow Corning Silicone.
The content of the surfactant in the ink is preferably 0.01 to 3.0% by weight, and more preferably 0.5 to 2.0% by weight. If the content is less than 0.01% by weight, the effect of adding the surfactant may be lost. If the content exceeds 3.0% by weight, the permeability to the recording medium becomes higher than necessary, and the image density decreases. And strikethrough may occur.

The pH adjuster is not particularly limited as long as it can adjust the pH to 7 to 11 without adversely affecting the ink to be prepared, and can be appropriately selected according to the purpose. And alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates, and the like. When the pH is less than 7 or exceeds 11, the amount of the ink-jet head or ink supply unit that melts out increases, and problems such as ink deterioration, leakage, and ejection failure may occur.
Examples of alcohol amines include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, and the like.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.
Examples of the ammonium hydroxide include ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, and the like.
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

Examples of the antiseptic / antifungal agent include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, sodium pentachlorophenol, and the like.
Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like.
Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like.

Examples of the antioxidant include phenol-based antioxidants (including hindered phenol-based antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.
Examples of phenolic antioxidants (including hindered phenolic antioxidants) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4 , 4'-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) Propionyloxy] ethyl] -2,4,8,10-tetrixaspiro [5,5] undecane, 1,1,3-to Lis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) Benzene, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, and the like.

Examples of amine-based antioxidants include phenyl-β-naphthylamine, α-naphthylamine, N, N′-di-sec-butyl-p-phenylenediamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, butylhydroxyanisole, 2,2'-methylenebis (4-methyl -6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), tetrakis [methylene-3- (3,5-di-tert-butyl-4-dihydroxyphenyl) propionate And methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, and the like.
Examples of the sulfur-based antioxidant include dilauryl-3,3′-thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl. -Β, β'-thiodipropionate, 2-mercaptobenzimidazole, dilauryl sulfide and the like.
Examples of phosphorus antioxidants include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, and trinonylphenyl phosphite.

Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a salicylate ultraviolet absorber, a cyanoacrylate ultraviolet absorber, and a nickel complex ultraviolet absorber.
Examples of benzophenone-based ultraviolet absorbers include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone and the like can be mentioned.
Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- ( 2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole and the like.
Examples of salicylate-based ultraviolet absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like.
Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3′-diphenyl acrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate, and butyl-2-cyano. -3-methyl-3- (p-methoxyphenyl) acrylate and the like.
Examples of the nickel complex ultraviolet absorber include nickel bis (octylphenyl) sulfide, 2,2′-thiobis (4-tert-octylferrate) -n-butylamine nickel (II), 2,2′-thiobis ( 4-tert-octylferrate) -2-ethylhexylamine nickel (II), 2,2′-thiobis (4-tert-octylferrate) triethanolamine nickel (II), and the like.

The ink of the present invention can also be used for full-color ink jet recording in combination with color inks such as magenta, cyan, yellow, and colorless ink.
Examples of the magenta pigment include Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, Pigment Violet 19, and the like. It is done.
Examples of the cyan pigment include pigment blue 1, 2, 3, 15, 15: 3, 15: 4, 16, 22, 60, and bat blue 4, 60.
Examples of the yellow pigment include pigment yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 120, 128, 129, 138, 150. 151, 154, 155, 180 and the like.
By using Pigment Yellow 74 as the yellow pigment, Pigment Red 122 and Pigment Violet 19 as the magenta pigment, and Pigment Blue 15 as the cyan pigment, it is possible to obtain a balanced ink with excellent color tone and light resistance.
The pigment concentration in the ink is preferably 0.1 to 50% by weight, particularly preferably 0.1 to 30% by weight.

The ink of the present invention is a known method, for example, a pigment dispersion, water, a water-soluble organic solvent, a surfactant, etc., and agitation and mixing using a sand mill, ball mill, roll mill, bead mill, nanomizer, homogenizer, ultrasonic disperser, etc. The coarse particles are then filtered through a filter, a centrifugal separator or the like, and deaerated as necessary.
The concentration of the pigment in the ink is preferably 1 to 20% by weight with respect to the total amount of the ink. If the amount is less than 1% by weight, the image density is low and the printed image lacks sharpness. If the amount is more than 20% by weight, not only the viscosity of the ink tends to increase, but also nozzle clogging tends to occur.
The content of the water-soluble organic solvent is 50% by weight or less, preferably 5 to 40% by weight, more preferably 10 to 35% by weight, based on the total amount of the ink.
In addition, the ink may be blended with additives similar to the materials described for the additive to the pigment dispersion, if necessary.

In the image forming method of the present invention, ink and a pretreatment liquid that causes aggregation / thickening action may be used in combination. If the surface of the recording medium is processed with the pretreatment liquid and then image formation is performed with the ink of the present invention, an effect of improving the image density is further observed.
The pretreatment liquid contains a water-soluble metal salt as an aggregating agent for the ink, and the metals include alkali metals, divalent metals such as Ca, Cu, Ni, Mg, Zn and Ba, and trivalent metals such as Al, Fe and Cr. A metal is mentioned. Examples of the anion constituting the water-soluble metal salt include citric acid, tartaric acid, acetic acid, lactic acid, oxalic acid, carbonic acid, fumaric acid, salicylic acid, benzoic acid and other organic acid ions, OH, Cl, NO ₃ , I, Br And inorganic ions of ClO ₃ . Also included are aluminum potassium sulfate, aluminum sulfate and the like. Particularly, Ca and Mg salts have a large aggregation effect, and CaCl ₂ , MgCl ₂ , and CaCO ₃ are preferable.
The water-soluble metal salt dissolves in water and becomes an ionic state, and has a function of destroying and aggregating the surface charge of the pigment dispersion. The content of the water-soluble metal salt in the pretreatment liquid is preferably 1 to 10% by weight.
As necessary, the pretreatment liquid may be a resin, a wetting agent, a surfactant, a penetrating agent, a pH adjuster, an antiseptic / antifungal agent, a chelating reagent, an antirust agent, an antioxidant, an ultraviolet absorber, an oxygen absorber, Various additives such as a light stabilizer can be blended. Details of these additives are the same as those of the ink additives described above.
As a method for treating the surface of the recording medium with the pretreatment liquid, a known method such as an ink jet method, spraying, roll coating, or wire-bar can be used.

The ink and the pretreatment liquid can be stored in a container and used as a cartridge.
In addition, the ink of the present invention or a set of pretreatment liquid and ink is contained in a container to form a cartridge, and an ink jet recording apparatus equipped with the ink can be printed on a recording medium to obtain an image formed product.
The printing method includes a continuous jet type and an on-demand type, and examples of the on-demand type include a piezo method, a thermal method, and an electrostatic method.

An example of the image forming method of the present invention and an ink jet recording apparatus for carrying out the method will be described with reference to the drawings.
The ink jet recording apparatus shown in FIG. 1 is equipped with a cartridge (20) containing pretreatment liquid and ink, and the pretreatment liquid and ink are supplied from this cartridge to the recording head. Here, the cartridge (20) is mounted in a state where the pretreatment liquid and the ink for each color are separated.
The recording head (1) is mounted on a carriage (18) and moved while being guided by guide shafts (21) and (22) by a timing belt (23) driven by a main scanning motor (24). On the other hand, the recording medium is placed at a position facing the recording head by the platen.
In the figure, (2) is the main body housing, (7) is the processing liquid and recording liquid common cartridge, (16) is the gear mechanism, (17) is the sub-scanning motor, (25) is the gear mechanism, and (26) is the main mechanism. A scanning motor (27) is a gear mechanism.

FIG. 2 is an enlarged view of the nozzle surface of an example of the recording head. A nozzle (30) for discharging the pretreatment liquid is provided in the vertical direction, and yellow ink, magenta ink, cyan ink, and black ink are discharged from the nozzles (31), (32), (33), and (34), respectively.
Further, as shown in FIG. 3, it is possible to arrange all the nozzles of the recording head in the horizontal direction. The nozzles (35) and (40) in the figure are pretreatment liquid discharge nozzles, and the nozzles (36), (37), (38) and (39) are respectively yellow ink, magenta ink, cyan ink and black. Ink is ejected. In such a recording head, since the pretreatment liquid discharge nozzles are provided at the left and right ends, printing is possible in both the forward path and the backward path in which the recording head reciprocates on the carriage. In other words, it is possible to attach the pretreatment liquid first in both the forward pass and the return pass and then attach the color ink from the top, or vice versa, and the difference in image density due to the difference in the moving direction of the recording head. Does not occur.
The ink jet recording apparatus can be replenished with pretreatment liquid and ink by replacing the cartridge. Further, this cartridge may be integrated with the recording head.

4 and 5 show cartridges that can store the pretreatment liquid and ink. This cartridge can store both the pretreatment liquid and the ink.
There is a liquid absorber 42 inside the cartridge housing 41, and the ink can be held in the cartridge by absorbing the ink or the pretreatment liquid. An upper lid member 44 is provided at the upper part of the cartridge, and ink or pretreatment liquid can be filled into the cartridge from an atmosphere opening 47 provided in the upper lid member 44. After filling, the atmosphere opening 47 is sealed by the seal member 55. Ink or pretreatment liquid is supplied from the liquid supply port 45 to the recording head. The cartridge positioning portion 71 has a protruding shape, and the cartridge position can be made constant by being overlapped with the concave portion of the cartridge housing portion of the printer main body. The cartridge attaching / detaching protrusion 81, the cartridge attaching / detaching finger hook 81a, and the cartridge attaching / detaching depression 82 can be fixed by an uneven portion of the cartridge housing portion of the printer main body when the cartridge is tried on. 43 is a case, 46 is a seal ring, 48 is a groove, 50 is a cap member, 51 is a protrusion for preventing liquid leakage, 53 is a cap member, and A is a space between the cartridge housing 41 and the liquid absorber 42. .
Most preferably, the ink and the pretreatment liquid are discharged from the recording head in the same location. However, in the present invention, for example, the pretreatment liquid is thinned out and applied, and the ink is overlaid on the pretreatment liquid enlarged by bleeding or the like, or the pretreatment liquid is applied only to the contour portion of the image, and the ink is formed thereon. A sufficient effect can be obtained by overlapping a part of the above.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these Examples.
In Examples and Comparative Examples, pigment dispersions were prepared and inks were prepared using the pigment dispersions. In the examples, “parts” and “%” are based on weight.

Example 1
<Preparation of oxidized carbon black of Example 1>
Degussa carbon black: 200 g of PRINTEX-U is put in a cylindrical ozone treatment device, ozone is generated by an ozone generator (Kotohira Kogyo Co., Ltd .: KQS-120), and the treatment temperature is about under an ozone atmosphere. Oxidation treatment was performed while maintaining the temperature at 30 ° C. to obtain oxidized carbon black of Example 1. The obtained carbon black had a volatilization amount of 10.3% and a BET specific surface area of 110 m ² / g.

<Preparation of pigment dispersion of Example 1>
(Pigment dispersion formulation)
-20.0 parts of oxidized carbon black of Example 1-70.0 parts of distilled water

A 20% aqueous solution of NaOH was added to the material of the above formulation to adjust the pH to 7.0, and distilled water was added to adjust the total amount to 100 parts. The 20% NaOH aqueous solution used was 1.2 parts.
Next, after premixing the above pH-adjusted materials, a disk type bead mill (KDL type batch type manufactured by Shinmaru Enterprises Co., Ltd.) was used at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. using 0.3 mm zirconia beads. Dispersed for 5 minutes.
Coarse particles were separated by a centrifugal separator (Model 3600 manufactured by Kubota Corporation) to obtain a pigment dispersion of Example 1 having a volume average particle diameter of about 125 nm and a standard deviation of 60.2 nm.

<Creation of Ink of Example 1>
The materials having the following formulation were mixed and stirred for 30 minutes, then aminoethylpropanediol (40% aqueous solution) was added to adjust the pH to 10, and then mixed and stirred for 30 minutes to prepare the ink of Example 1.
(Ink formulation)
-Pigment dispersion of Example 1 (pigment concentration 20%) 40.0 parts-Glycerol 5.5 parts-1,3-butanediol 16.5 parts-2-ethyl-1,3-hexanediol 2.0 parts Fluorosurfactant (solid content 40%) 2.5 parts (DuPont: Zonyl FS-300)
Fluoroethylene / vinyl ether alternating copolymer (solid content 50%) 6.0 parts (Asahi Glass Co., Ltd .: Lumiflon FE4300, volume average particle diameter 150 nm,
MFT 30 ℃ or less)
・ Distilled water 18.6 parts

Examples 2-9
<Creation of oxidized carbon black in Examples 2 to 9>
Except that the oxidized carbon black (CB) shown in the column of Examples 2 to 9 in Table 1 was used in place of the oxidized carbon black used in Example 1, and the ozone generation amount / treatment time was adjusted, this was implemented. In the same manner as in Example 1, oxidized carbon blacks of Examples 2 to 9 were prepared.

<Preparation of pigment dispersions of Examples 2 to 9>
The same as Example 1 except that the oxidized carbon black of Examples 2 to 9 was used instead of the oxidized carbon black used in Example 1 and the pH was adjusted to 7 by changing the addition amount of a 20% aqueous solution of NaOH. Thus, pigment dispersions of Examples 2 to 9 were obtained.

<Creation of inks of Examples 2 to 9>
Inks of Examples 2 to 9 were prepared in the same manner as Example 1 except that the pigment dispersions of Examples 2 to 9 (pigment concentration 20%) were used instead of the pigment dispersions used in Example 1. did.

Examples 10-11
<Preparation of pigment dispersions of Examples 10 to 11>
Instead of the oxidized carbon black used in Example 1, the oxidized carbon black used in Example 2 was used, and the pH was adjusted to 6 (Example 10) and 8 (Example) by changing the addition amount of a 20% NaOH aqueous solution. Except the point adjusted to 11), it carried out similarly to Example 1, and obtained the pigment dispersion of Examples 10-11.
<Creation of inks of Examples 10 to 11>
Inks of Examples 10 to 11 were prepared in the same manner as Example 1, except that the pigment dispersions of Examples 10 to 11 (pigment concentration 20%) were used instead of the pigment dispersions used in Example 1. did.

<Preparation of pigment dispersion of Example 12>
(Pigment dispersion formulation)
-20.0 parts of oxidized carbon black of Example 1-70.0 parts of distilled water

After adding a 20% aqueous solution of NaOH to the material of the above formulation and adjusting the pH to 7.0, distilled water was added to adjust the total amount to 97 parts. The 20% NaOH aqueous solution used was 1.2 parts.
Next, after premixing the above pH-adjusted materials, a disk type bead mill (KDL type batch type manufactured by Shinmaru Enterprises Co., Ltd.) was used at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. using 0.3 mm zirconia beads. Dispersed for 5 minutes.
Next, 7.0 parts of an ether type polyurethane resin (manufactured by Mitsui Chemicals, acid value 80, solid content 28%) was added and stirred well, and then coarse particles were removed with a centrifuge (Model 3600 manufactured by Kubota Corporation). This was separated to obtain a pigment dispersion of Example 12 having a volume average particle diameter of about 125 nm and a standard deviation of 60.2 nm.

<Creation of Ink of Example 12>
The material having the following formulation was mixed and stirred for 30 minutes, then aminoethylpropanediol (40% aqueous solution) was added to adjust the pH to 10, and then mixed and stirred for 30 minutes to prepare the ink of Example 12.
(Ink formulation)
-Pigment dispersion of Example 12 (pigment concentration 20%)-40.0 parts-Glycerol 5.5 parts-1,3-butanediol 16.5 parts-2-ethyl-1,3-hexanediol 2.0 parts Fluorosurfactant (solid content 40%) 2.5 parts (DuPont: Zonyl FS-300)
Fluoroethylene / vinyl ether alternating copolymer (solid content 50%) 6.0 parts (Asahi Glass Co., Ltd .: Lumiflon FE4300, volume average particle diameter 150 nm,
MFT 30 ℃ or less)
・ Distilled water 18.6 parts

Examples 13-20
<Preparation of oxidized carbon black of Examples 13 to 20>
Instead of the carbon black PRINTEX-U manufactured by Degussa used in Example 1, pre-oxidation carbon black (CB) shown in the columns of Examples 13 to 20 in Table 1 was used to adjust the ozone generation amount / treatment time. Except for the points, oxidized carbon blacks of Examples 13 to 20 were produced in the same manner as Example 1.

<Preparation of pigment dispersions of Examples 13 to 20>
Similar to Example 12 except that the oxidized carbon black of Examples 13 to 20 was used instead of the oxidized carbon black used in Example 12, and the pH was adjusted to 7 by changing the addition amount of a 20% aqueous solution of NaOH. Thus, pigment dispersions of Examples 13 to 20 were obtained.

<Creation of inks of Examples 13 to 20>
Inks of Examples 13 to 20 were prepared in the same manner as Example 12 except that the pigment dispersions of Examples 13 to 20 (pigment concentration 20%) were used instead of the pigment dispersions used in Example 12. did.

Examples 21-22
<Preparation of pigment dispersions of Examples 21 to 22>
The oxidized carbon black used in Example 2 was used in place of the oxidized carbon black used in Example 12, and the pH was adjusted to 6 (Example 21) and 8 (Example) by changing the addition amount of a 20% NaOH aqueous solution. Except having adjusted to 22), it carried out similarly to Example 12, and obtained the pigment dispersion of Examples 21-22.

Examples 23-26
<Preparation of pigment dispersions of Examples 23 to 26>
In place of the oxidized carbon black used in Example 12, the oxidized carbon black used in Example 2 was used, and instead of an ether type polyurethane resin (manufactured by Mitsui Chemicals, acid value 80, solid content 28%), Table 1 Pigment dispersions of Examples 23 to 26 were obtained in the same manner as in Example 12, except that the described acid value ether type polyurethane resin (manufactured by Mitsui Chemicals, Inc., 28% solid content diluted product) was used.

<Creation of inks of Examples 23 to 26>
Inks of Examples 23 to 26 were prepared in the same manner as Example 12 except that the pigment dispersions of Examples 23 to 26 (pigment concentration 20%) were used instead of the pigment dispersions used in Example 12. did.

Example 27
<Preparation of pigment dispersion of Example 27>
The oxidized carbon black used in Example 2 was used instead of the oxidized carbon black used in Example 12, and a 20% aqueous solution of LiOH was used instead of the 20% aqueous solution of NaOH, and the addition amount was adjusted to adjust the pH. Except for the point adjusted to 7, a pigment dispersion of Example 27 was obtained in the same manner as Example 12.

<Creation of Ink of Example 27>
In the same manner as in Example 12, except that the pigment dispersion (pigment concentration 20%) used in Example 27 was used instead of the pigment dispersion (pigment concentration 20%) used in Example 12. 27 inks were prepared.

Comparative Examples 1-10
<Creation of oxidized carbon black of Comparative Examples 1 to 10>
In place of the carbon black used in Example 1, pre-oxidation carbon black (CB) shown in each column of Comparative Examples 1 to 10 in Table 1 was used, except that the ozone generation amount / treatment time was adjusted. In the same manner as in Example 1, oxidized carbon blacks of Comparative Examples 1 to 10 were prepared.

<Creation of pigment dispersions of Comparative Examples 1 to 10>
The same as Example 1 except that the oxidized carbon black of Comparative Examples 1 to 10 was used instead of the oxidized carbon black used in Example 1, and the pH was adjusted to 7 by changing the addition amount of a 20% aqueous solution of NaOH. Thus, pigment dispersions of Comparative Examples 1 to 10 were obtained.

<Creation of inks of Comparative Examples 1 to 10>
Inks of Comparative Examples 1 to 10 were prepared in the same manner as in Example 1 except that the pigment dispersion of Comparative Examples 1 to 10 (pigment concentration 20%) was used instead of the pigment dispersion used in Example 1. did.

Comparative Example 11
<Preparation of oxidized carbon black of Comparative Example 11>
Carbon black PRINTEX-U (100 g) manufactured by Degussa was mixed with 500 g of distilled water, 1000 g of sodium hypochlorite aqueous solution (12%) was added dropwise with stirring, and the mixture was boiled for 6 hours for wet oxidation. Subsequently, after filtering with glass fiber and washing | cleaning with distilled water, it was made to dry with a 100 degreeC high temperature tank. The obtained carbon black had a volatilization amount of 13% and a BET specific surface area of 110 m ² / g.

<Preparation of Pigment Dispersion of Comparative Example 11>
The same procedure as in Example 1 was conducted except that the oxidized carbon black of Comparative Example 11 was used instead of the oxidized carbon black used in Example 1, and the pH was adjusted to 7 by changing the addition amount of a 20% aqueous NaOH solution. A pigment dispersion of Comparative Example 11 was obtained.

<Creation of Ink of Comparative Example 11>
Ink of Comparative Example 11 was prepared in the same manner as in Example 1 except that the pigment dispersion of Comparative Example 11 (pigment concentration 20%) was used instead of the pigment dispersion used in Example 1.

Comparative Example 12
<Creation of oxidized carbon black of Comparative Example 12>
Carbon black PRINTEX-U (100 g) manufactured by Degussa was mixed with 500 g of distilled water, and 600 g of peroxodisulfuric acid Na aqueous solution (10%) was added dropwise with stirring, followed by boiling for 6 hours for wet oxidation. Subsequently, after filtering with glass fiber and wash | cleaning with distilled water, it was made to dry with a 100 degreeC high temperature tank. The obtained carbon black had a volatilization amount of 13% and a BET specific surface area of 110 m ² / g.

<Preparation of Pigment Dispersion of Comparative Example 12>
The same procedure as in Example 1 was performed except that the oxidized carbon black of Comparative Example 12 was used instead of the oxidized carbon black used in Example 1, and the pH was adjusted to 7 by changing the addition amount of a 20% aqueous solution of NaOH. A pigment dispersion of Comparative Example 12 was obtained.

<Creation of Ink of Comparative Example 12>
Ink of Comparative Example 12 was prepared in the same manner as in Example 1 except that the pigment dispersion of Comparative Example 12 (pigment concentration 20%) was used instead of the pigment dispersion used in Example 1.

Comparative Examples 13-14
<Preparation of Pigment Dispersions of Comparative Examples 13-14>
The oxidized carbon black used in Example 2 was used instead of the oxidized carbon black used in Example 1, and the pH was adjusted to 5 (Comparative Example 13) and 9 (Comparative Example 14) by changing the addition amount of a 20% aqueous solution of NaOH. The pigment dispersions of Comparative Examples 13 to 14 were obtained in the same manner as in Example 1 except for the point adjusted to.

<Creation of Inks of Comparative Examples 13-14>
Inks of Comparative Examples 13 to 14 were prepared in the same manner as in Example 1 except that the pigment dispersions of Comparative Examples 13 to 14 (pigment concentration 20%) were used instead of the pigment dispersions used in Example 1. did.

The inks of the above examples and comparative examples were filled in cartridges, mounted on the ink jet printer shown in FIG. 1, and subjected to printing experiments. The image density and storage stability were evaluated as follows. The results are shown in Tables 1 and 2.
(1) Storage stability Each ink was sealed and stored at 70 ° C. for 2 weeks, the viscosity before and after storage was measured, and the viscosity change rate was calculated by the following formula. The smaller the value of the viscosity change rate, the better.
Viscosity change rate (%) = (viscosity after storage−viscosity before storage) × 100 / viscosity before storage (2) Image density Printed on Xerox PPC paper 4024 (non-smooth paper) with the inkjet printer shown in FIG. Images were measured with an Xrite densitometer 938. Larger numbers are better.

DESCRIPTION OF SYMBOLS 1 Recording head 2 Main body housing | casing 7 Processing liquid and recording liquid common cartridge 16 Gear mechanism 17 Subscanning motor 18 Carriage 20 Recording liquid cartridge 21 Guide shaft 22 Guide shaft 23 Timing belt 24 Main scanning motor 25 Main scanning motor 26 Main scanning motor 27 Main scanning motor 31 Nozzle for discharging processing liquid 32 Nozzle for discharging recording liquid 33 Nozzle for discharging recording liquid 34 Nozzle for discharging recording liquid 35 Nozzle for discharging recording liquid 36 Processing liquid is discharged Nozzle 37 Nozzle from which recording liquid is ejected 38 Nozzle from which recording liquid is ejected 39 Nozzle from which recording liquid is ejected 40 Nozzle from which recording liquid is ejected 41 Cartridge housing 42 Liquid absorber 43 Case 44 Upper lid member 45 Liquid supply port 46 Seal ring 47 Air release port 8 groove 50 recess A space cap member 51 leakage preventing projection 53 the cap member 55 sealing member 71 cartridge positioning portion 81 cartridge detachable protruded portion 81a cartridge for attaching and detaching the finger hook portion 82 cartridge detachable

JP 2000-319572 A JP 2004-224955 A Japanese Patent Laid-Open No. 10-324818 JP 2001-164148 A JP 11-349849 A

Claims (5)

Water, a pigment dispersion adjusted to pH 6 to 8 and a penetrant, and the pigment is ozone-oxidized carbon black having a BET specific surface area of 90 to 150 m ² / g to have a volatile content of 10 to 20%. An ink for ink-jet recording, characterized by being carbon black.   A cartridge comprising the ink jet recording ink according to claim 1 contained in a container.   An ink jet recording apparatus comprising the cartridge according to claim 2.   An image forming method using the ink for ink jet recording according to claim 1 and forming an image using an ink jet recording apparatus provided with an ink discharge head.   An image formed article printed using the ink for ink jet recording according to claim 1.

Images