JP2012082293A - Inkjet recording ink, cartridge, inkjet recording apparatus, and image-formed material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an inkjet recording ink that has excellent pigment dispersibility, excellent storage stability, and can achieve high image density even on a non-smooth paper; a cartridge using the ink; an inkjet recording apparatus; and an image-formed material.SOLUTION: The inkjet recording ink comprises: a pigment dispersion containing a pigment, a dispersant, and water; and a water-soluble organic solvent. The inkjet recording ink contains, as the dispersant, a styrene-maleic anhydride-acrylamide copolymer salt, and has pH of ≥8.0.

Description

The present invention relates to an ink for ink jet recording, a cartridge using the ink, an ink jet recording apparatus, and an image formed product.

In recent years, as an image forming method, the process is simple as compared to other recording methods, and full colorization is easy, and there is an advantage that a high-resolution image can be obtained even with an apparatus having a simple configuration. Inkjet recording systems have become widespread.
In the ink jet recording method, a small amount of ink is ejected by bubbles generated by heat, or pressure generated by using piezoelectricity or electrostatic force, and adhered to an image forming body such as paper, and then quickly dried (or coated). This is an image forming method in which an image is formed by penetrating into an image forming body, and has been expanded to printers for industrial use including personal and printing applications.
In recent years, demand for industrial applications has increased, and high-speed printing and adaptability to various recording media (media such as paper) are desired. In particular, an ink jet printer equipped with a line head has become necessary as the speed increases. In recent years, there has been a growing demand for water-based inks from the viewpoints of environment and safety.

However, water-based inks are easily affected by the medium, causing various problems in image quality such as image density and bleeding. In particular, when non-smooth paper is used as the medium, the influence on the image density is significant. 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, there is a problem that was not seen with solvent inks, in which the color density of the formed color material is low.
In recent years, in particular, as high-speed printing progresses, in order to increase the drying speed of the ink attached to the medium, means for increasing the speed of drying by adding a penetrant to the ink and allowing the solvent water to permeate the medium has been taken. . However, unlike the ink used for paints and ballpoint pens, the inclusion of a penetrant improves the permeability of not only water but also the coloring material to the media, and the image density is further reduced. appear.

Various proposals have been made to deal with the above problems. For example, Patent Document 1 discloses an invention for improving the image density of a matte print medium by defining the characteristics of carbon black. . Examples of the resin dispersant include copolymers composed of various monomers, but only the styrene / acrylic resin corresponding to Comparative Example 1 of the present invention is used in the examples. The problem of the present invention cannot be solved.
Patent Document 2 discloses an invention related to an ink containing a pigment whose surface is coated with a polymer compound, and Patent Document 3 discloses an invention related to an ink containing a water-dispersible pigment coated with a polymer dispersant. Are disclosed, and styrene-maleic anhydride copolymer or water-soluble styrene-maleic acid resin is exemplified as a polymer compound or a polymer dispersant, but it relates to a ternary copolymer used in the present invention. There is no description. In these inventions, when an image is formed on non-smooth paper, the pigment does not stay so much on the paper surface, and a sufficient image density cannot be obtained.

  The present invention has been made in view of the above prior art, and uses an ink for ink jet recording, which has good dispersibility of pigments, good storage stability, and can achieve high image density even on non-smooth paper. An object is to provide a cartridge, an ink jet recording apparatus, and an image formed product.

The above problems are solved by the following inventions 1) to 5).
1) A pigment dispersion containing a pigment, a dispersant, and water, and an inkjet recording ink containing a water-soluble organic solvent, which contains a styrene-maleic anhydride-acrylamide copolymer salt as the dispersant. And an ink for ink-jet recording having a pH of 8.0 or more.
2) The inkjet recording ink according to 1), wherein the copolymer salt is a Na salt.
3) A cartridge in which the ink for ink jet recording described in 1) or 2) is contained in a container.
4) An ink jet recording apparatus comprising the cartridge according to 3).
5) An image formed product printed using the ink for ink jet recording described in 1) or 2).

  According to the present invention, an ink for ink jet recording having good dispersibility of pigment, good storage stability, and high image density even on non-smooth paper, a cartridge using the ink, an ink jet recording apparatus, and an image formed article are provided. Can be provided.

It is a figure which shows an example of the inkjet recording device of this invention.

Hereinafter, the present invention will be described in detail.
The ink for ink jet recording of the present invention (hereinafter sometimes simply referred to as ink) is characterized by using a styrene-maleic anhydride-acrylamide copolymer salt (ternary copolymer salt) as a pigment dispersant. It is important that it is a copolymer (ternary copolymer) of these three types of monomers, and in particular, it is important to use maleic acid having two carboxyl groups.
A copolymer of maleic anhydride and acrylamide tends to form a hydrogen bond between the carboxylic acid group derived from maleic anhydride and acrylamide. Therefore, when the copolymer is used in a water-based ink, the intermolecular distance between the copolymer molecules becomes small when the ink comes into contact with an image forming medium such as paper and the solid content increases due to moisture evaporation or the like. The pigments stay on the paper surface due to the generation of hydrogen bonds and aggregation / thickening, so that a high image density is expected.
However, in reality, the effect of increasing the image density is not so great, and it has been found that the ink is thickened when stored for a long period of time and lacks storage stability.

As a result of intensive studies, it was found that if a ternary copolymer salt obtained by adding styrene to maleic anhydride and acrylamide is used, the storage stability is improved and a high image density can be obtained.
The reason why the stability of storage and the effect of high image density can be obtained is not clear, but for the improvement of image density, when maleic anhydride having two carboxyl groups is used, the ink comes into contact with paper during image formation. In addition, not only hydrogen bonds with acrylamide, but also calcium ions of calcium carbonate contained in many papers and maleic anhydride having two carboxyl groups form a complex to insolubilize and increase cohesion, and When styrene is added, the adsorption of the copolymer to the pigment becomes stronger, the copolymer can cover the periphery of the pigment particles, and the function of efficiently agglomerating and aggregating the pigment on the paper surface is added. It is presumed that this is due to a large amount of remaining on the paper.
For improved storage stability, the use of maleic anhydride having two carboxyl groups improves water solubility in a state where the solid content is not high, inhibits unnecessary hydrogen bonding, and aromatic rings. It is presumed that the addition of styrene having a value makes it easier for the copolymer to localize on the pigment surface, resulting in less contact between the copolymer molecules.

  The ternary copolymer is used as a salt. It is a carboxyl group that forms a salt. Examples of the salt include alkali metal salts such as Li, Na and K, ammonium, mono, di or trimethylamine, mono, di or triethylamine, monoethanolamine, diethanolamine and triethanol. Organic amine salts such as amine, methylethanolamine, methyldiethanolamine, dimethylethanolamine, choline, aminoethanepropanediol, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, trishydroxymethylaminomethane, aminoethylpropanediol Organic amine salts such as cyclic amines such as morpholine, N-methylmorpholine, N-methyl-2-pyrrolidone and 2-pyrrolidone. In particular, the Li salt and the Na salt are preferable, and the Na salt is most preferable in terms of the effect of improving image density.

The ink of the present invention has a pH of 8.0 or higher. This is because it is necessary to disperse at a pH of 8.0 or higher when preparing a pigment dispersion using the ternary copolymer salt. Preferably, the pH is about 8.5 to 11.0. If the pH is less than 8.0, the solubility of the ternary copolymer salt is poor, the dispersibility of the pigment dispersion is poor, the viscosity is high even when ink is formed, the storage stability of the ink is deteriorated, and the ejection stability is also improved. This is because there is an influence.
The pH adjuster can be appropriately selected according to the purpose, and examples thereof include alcohol amines, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, and alkali metal carbonates.
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, potassium hydroxide and the like.
Examples of the ammonium hydroxide include ammonium hydroxide and quaternary ammonium hydroxide.
Examples of the phosphonium hydroxide include (1,3-dioxolan-2-yl) methyltriphenylphosphonium bromide, (1-naphthylmethyl) triphenylphosphonium chloride, (2,4-dichlorobenzyl) triphenylphosphonium chloride, and the like. .
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

The pigment dispersion used in the present invention is obtained by dispersing a pigment, a dispersant, water, and various additives added as necessary, for example, with a disperser such as a bead mill and then dispersing with a beadless mill or the like. .
Specific examples of the bead mill include dyno mill KDL type (manufactured by Shinmaru Enterprises), agitator mill LMZ (manufactured by Ashizawa Finetech), SC mill (manufactured by Mitsui Mining). Specific examples of the beadless mill include a high-speed shear force type CLEAR SS5 (manufactured by M Technique), Cavitron CD1010 (manufactured by Eurotech), module DR2000 (manufactured by Shinmaru Enterprises), K. Examples include Philmix (manufactured by Koki Kogyo Kogyo Co., Ltd.), ultra-high pressure collision type artemizer (manufactured by Sugino Machine Co., Ltd.), and nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.).
Further, by pre-processing coarse particles with a homogenizer or the like in the pre-process of the disperser, the particle size distribution can be further sharpened, leading to improvements in image density, ejection stability, and the like.
The beads used in the bead mill are usually ceramic beads, and zirconia balls are generally used. The bead diameter is preferably 0.05 mmφ or less, more preferably 0.03 mmφ or less.

The polymerization method of the ternary copolymer is not particularly limited, and a known polymerization method may be employed. For example, a monomer and a polymerization initiator may be added using water as a medium, and polymerization may be performed at room temperature to 100 ° C.
The composition ratio of the monomers is preferably in the range of 20 mol% or more of styrene, 10 to 75 mol% of maleic anhydride, and 70 mol% or less of acrylamide.
Moreover, the thing of the range of 500-20000 (GPC method, pullulan conversion) is preferable in a weight average molecular weight, and 1000-10000 are more preferable at the surface of ink viscosity or pigment adsorption.

The pigment is not particularly limited, and known pigments can be used.
Carbon black is preferable as the black pigment, and examples thereof include ketjen black, furnace black, acetylene black, thermal black, and gas black.
Further, carbon black surfaces that have been oxidized or alkali-treated, those that are coated with various surfactants or resins, or those that have been grafted or encapsulated can be used.
In particular, when acidic carbon obtained by oxidizing the carbon black surface is used, the drying property is improved and the effect of improving the image density is great.
Also, carbon black coated with a resin having a sulfonic acid group or a carboxyl group, or imparted with these functional groups by grafting can be used.

Specific examples of acidic carbon include MA7, MA8, MA100, MA600, # 45, # 50, # 2200B, # 2350, # 2650, OIL 7B, OIL 11B (manufactured by Mitsubishi Kasei), Raven 1035, Raven 1040, Raven 1060, Raven 1080, Raven 1255, Raven 3500, Raven C (manufactured by Columbia), REGAL400R, MOGUL L (manufactured by Cabot), Color Black FW1, Color Black FW18, Color Black 160 Sack, Color Black S150, Color Black S150, Color Black S150, Color Black S150, Color Black S150, Color Black S150, Color Black S150, Color Black S150 U, Printex V, Printex 75, Printex 140U, Printex 140V, Special Black 4 , Special Black 100, Special Black 250, Special Black 350, NIPEX150, NIPEX180IQ (manufactured by Degussa).
Among these, carbon black having a pH of 5 or less and a volatile content of 3.5 to 8.0% by weight is preferable, and gas black is preferable in terms of drying property and image density.

Examples of magenta pigments include Pigment Red 5, Pigment Red 7, Pigment Red 12, Pigment Red 48 (Ca), Pigment Red 48 (Mn), Pigment Red 57 (Ca), Pigment Red 57: 1, Pigment Red 112, Pigment Red 122, Pigment Red 123, Pigment Red 168, Pigment Red 184, Pigment Red 202, Pigment Violet 19 and the like.
Examples of cyan pigments include Pigment Blue 1, Pigment Blue 2, Pigment Blue 3, Pigment Blue 15, Pigment Blue 15: 3, Pigment Blue 15: 4, Pigment Blue 16, Pigment Blue 22, Pigment Blue 60, Bat Blue 4 , Bat Blue 60 and the like.
Examples of yellow pigments include Pigment Yellow 1, Pigment Yellow 2, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 16, Pigment Yellow 17, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 75 Pigment Yellow 83, Pigment Yellow 93, Pigment Yellow 95, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 114, Pigment Yellow 120, Pigment Yellow 128, Pigment Yellow 129, Pigment Yellow 138, Pigment Yellow 150, Pigment Yellow 151, Pigment Yellow 154, pigment yellow 155, pigment yellow 180, etc. It is below.
By using Pigment Red 122, Pigment Violet 19 as the magenta pigment, Pigment Blue 15 as the cyan pigment, and Pigment Yellow 74 as the yellow pigment, it is possible to obtain a balanced ink with excellent color tone and light resistance.

The above pigments may be used alone or in combination of two or more.
The pigment concentration in the pigment dispersion is preferably 0.1 to 50% by weight, particularly preferably 0.1 to 30% by weight.
The ternary copolymer has the most remarkable effect of improving image density when carbon black is used as a pigment.

The blending amount of the dispersant is appropriately adjusted according to the type of pigment. Usually, the amount is about 0.005 to 5 parts by weight with respect to 1 part by weight of the pigment, preferably 0.01 to 2 parts by weight, and more preferably 0.02 to 0.5 parts by weight. If the amount is 0.01 to 2 parts by weight, the dispersibility of the pigment is improved and the temporal stability of the pigment dispersion and the ink tends to be improved. If the amount is 0.02 to 0.5 parts by weight, the pigment dispersion is improved. The stability with time of the body and ink is further improved.
Further, it can be used in combination with other known dispersants as long as the effects of the present invention are not impaired. Examples of such a dispersant include various surfactants such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant, and polymer-type dispersants.

Examples of the anionic surfactant include alkyl sulfocarboxylate, α-olefin sulfonate, polyoxyethylene alkyl ether acetate, N-acyl amino acid and its salt, N-acylmethyl taurate, alkyl sulfate, polysulfate Oxyalkyl ether sulfate, polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester, lauryl alcohol sulfate ester, alkylphenol phosphate ester, naphthalenesulfonate formalin condensate, alkyl phosphate ester, alkyl allyl Examples include sulfonate, diethylsulfosuccinate, diethylhexylsulfosuccinate, and dioctylsulfosuccinate.
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 amide, propyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, And an imidazoline derivative etc. are mentioned.

Nonionic surfactants include the following.
Ether systems such as polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether and polyoxyallyl alkyl ether;
Polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate and polyoxyethylene stearate Esters such as rates;
2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol and 3,5-dimethyl-1-hexyn-3-ol Acetylene glycol system such as.

  The dispersion medium of the pigment dispersion desirably contains water, but various organic solvents may be used in combination as necessary. For example, as water-soluble organic solvents, 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-pyrrolidone and the like Pyrrolidone derivatives, ketones such as acetone and methyl ethyl ketone, alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine.

For pigment dispersions and inks, wetting agents, surfactants, penetrants, pH adjusters, antiseptic / antifungal agents, chelating reagents, rust preventives, antioxidants, UV absorbers, oxygen absorbers as necessary Various additives such as a light stabilizer can be blended.
Examples of the wetting agent are not particularly limited and may be appropriately selected depending on the purpose. For example, polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, Examples include 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, glycerin, trimethylolethane, trimethylolpropane, 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 compounds include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone, Etc.
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. Moreover, as derivatives of these saccharides, reducing sugars of the above-mentioned saccharides (for example, sugar alcohols represented by the general formula: HOCH ₂ (CHOH) _n CH ₂ OH (n = 2 to 5)), oxidation, etc. Sugar (for example, aldonic acid, uronic acid, etc.), amino acid, thioic acid and the like can be mentioned. Among these, sugar alcohols are preferable, and specific examples include maltitol and sorbit.
Among the above wetting agents, glycerin, diethylene glycol, triethylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol, 2-pyrrolidone, N-methyl from the viewpoint of storage stability and ejection stability. 2-pyrrolidone is particularly preferred.

The blending ratio of the pigment and the wetting agent has a great influence on the stability of ink ejection 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 by fluorine are preferable, and those having 4 to 16 carbon atoms are more preferable. When the fluorine-substituted carbon number is less than 2, the effect of fluorine may not be obtained, and when 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 purpose, and those that 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. Commercially available products can be easily obtained 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% 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 penetrant preferably contains at least one polyol compound having a solubility in water at 20 ° C. of 0.2 to 5.0% by weight. As a result, it is possible to increase the ink permeability and at the same time to eliminate the bleeding by keeping the pigment on the surface, and to obtain a printed image with a high image density and with little show-through.
Examples of such a polyol compound include 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3- Propanediol, 3,3-dimethyl-1,2-butanediol, 2,4-dimethyl-2,4-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,5-dimethyl- Examples include aliphatic diols such as 2,5-hexanediol, 2-ethyl-1,3-hexanediol, and 5-hexene-1,2-diol. 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 ink and adjusted to desired physical properties, and can be appropriately selected according to the purpose. For example, ethylene glycol monophenyl ether, Examples thereof include alkyl and aryl ethers of polyhydric alcohols such as ethylene glycol monoallyl ether, diethylene glycol monophenyl 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 content is less than 0.1% by weight, quick-drying may not be obtained and a blurred image may be obtained. If the content 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.

As the pH adjusting agent, the same materials as those used for adjusting the pH of the pigment dispersion described above can be used.
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 the phosphorus antioxidant 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- And cyano-3-methyl-3- (p-methoxyphenyl) acrylate.
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 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 it is less than 1% by weight, the image density is low, so that the printing is not clear. If it is more than 20% by weight, not only the viscosity of the ink tends to be high, 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.

When an image formed product is obtained using the ink of the present invention, a pretreatment liquid that causes aggregation / thickening action may be used in combination with the ink. If the recording medium surface is treated with the pretreatment liquid and then image formation is performed with the ink of the present invention, the image density can be further improved.
As the pretreatment liquid, those containing a water-soluble metal salt are preferable, and those showing acidity are particularly preferable.
Examples of metal ions that form water-soluble metal salts include alkali metal ions, divalent metal ions such as Ca, Cu, Ni, Mg, Zn, and Ba, and trivalent metal ions such as Al, Fe, and Cr. .
As anions constituting the water-soluble metal salt, organic acid ions such as citric acid, tartaric acid, acetic acid, lactic acid, oxalic acid, carbonic acid, fumaric acid, salicylic acid, benzoic acid, OH, Cl, NO ₃ , I, Br, An inorganic ion of ClO ₃ can be mentioned. Also included are aluminum potassium sulfate, aluminum sulfate and the like.
The amount of the water-soluble metal salt added to the pretreatment agent is preferably 1 to 10% by weight.

If necessary, the pretreatment liquid contains a wetting agent, surfactant, penetrating agent, pH adjuster, antiseptic / antifungal agent, chelating reagent, rust inhibitor, antioxidant, ultraviolet absorber, oxygen absorber, and light stability. Various additives such as an agent can be blended. Since these additives are the same as those for the pigment dispersion or ink described above, details thereof are omitted.
Further, a water-soluble metal salt (CaCl ₂ or the like), an alkyleneamine (long-chain alkyl isocyanate-modified polyethyleneimine or the like), an acid (lactic acid or maleic acid), or the like can be used as the ink aggregating agent.
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 cartridge of the present invention contains the ink of the present invention in a container. There are no particular restrictions on the container, and its shape, structure, size, material, etc. can be appropriately selected according to the purpose. For example, a container having an ink bag formed of an aluminum laminate film, a resin film, etc., plastic Examples include cases. Further, the pretreatment liquid may be accommodated together in the cartridge.
An ink jet recording apparatus of the present invention is equipped with the above cartridge and includes a head of a system for performing recording by discharging ink.
Examples of the printing (discharge) method include a continuous jet type and an on-demand type. Further, examples of the on-demand type include a piezo method, a thermal method, and an electrostatic method.
Here, the cartridge and the ink jet recording apparatus of the present invention will be described with reference to FIG.

In FIG. 1, an ink cartridge 20 that accommodates an ink jet recording ink of the present invention is accommodated in a carriage 18. Here, a plurality of ink cartridges 20 are provided for convenience, but it is not necessary to have a plurality. In such a state, the ink for ink jet recording is supplied from the ink cartridge 20 to the droplet discharge head 18 a mounted on the carriage 18. In FIG. 1, the discharge nozzle surface is in an invisible state because it faces downward, but ink jet recording ink is discharged from this discharge nozzle.
The droplet discharge head 18 a mounted on the carriage 18 is guided and moved by the guide shafts 21 and 22 by the timing belt 23 driven by the main scanning motor 26.
On the other hand, a specific coated paper (image support) is placed at a position facing the droplet discharge head 18 a by the platen 19. In FIG. 1, 1 is an ink jet recording apparatus, 2 is a main body housing,
Reference numeral 16 denotes a gear mechanism, 17 denotes a sub-scanning motor, and 25 and 27 denote gear mechanisms.

When recording is performed on an image support using an ink jet recording apparatus containing the ink or ink cartridge of the present invention, an image formed product printed on the image support on demand is obtained. Further, the replenishment of ink for ink jet recording can be replaced in units of ink cartridges.
There is no restriction | limiting in particular as said image support body, According to the objective, it can select suitably, For example, a plain paper, glossy paper, special paper, cloth, a film, an OHP sheet etc. are mentioned. Among these, paper is particularly preferable.

  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 the examples, “parts” and “%” are based on weight.

Example 1
<Preparation of Compound 1>
A four-necked flask was equipped with a thermometer, a stirrer, and a reflux condenser, charged with 500 g of water and 15 g of ammonium persulfate, and heated at 80 to 90 ° C., 100 g of styrene, 130 g of maleic anhydride, 140 g of 50% acrylamide aqueous solution, The solution was slowly added dropwise with stirring. The ratio (%) of styrene, maleic anhydride and acrylamide is 33:43:23.
Subsequently, after reacting for 4 hours, the mixture is cooled, neutralized with a 20% aqueous NaOH solution, further distilled water is added to adjust the solid content to 20%, and a styrene-maleic anhydride-acrylamide copolymer Na salt. An aqueous solution of (Compound 1) was obtained.

<Preparation of pigment dispersion 1>
After premixing the materials of the following formulation, milling was performed for 10 minutes using a bead mill (Dynomill KDL type batch type, manufactured by Shinmaru Enterprises Co., Ltd., using zirconia beads having a diameter of 0.05 mm), and then the pH was measured. The pH was measured with a pH meter (MP220 manufactured by METTER TOLEDO).
Subsequently, coarse particles were separated by a centrifugal separator (Model 3600 manufactured by Kubota Corporation) to obtain Pigment Dispersion 1 having a volume average particle diameter of about 120 nm and a standard deviation of 51.2 nm.
(Pigment dispersion formulation)
・ Carbon black NIPEX150 20.0 parts (Degussa: Gas black)
-Aqueous solution of Compound 1 (solid content 20%) 18.8 parts-NaOH 20% aqueous solution 1.2 parts-Distilled water 60.0 parts

<Creation of ink 1>
Ink 1 was prepared by mixing and stirring materials having the following formulation for 30 minutes.
(Ink formulation)
Pigment dispersion 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 Fluorine-based Surfactant (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, average particle size 150 nm,
MFT 30 ℃ or less)
-2-amino-2-ethyl-1,3-propanediol aqueous solution (solid content 40%)
1.5 parts ・ 26.0 parts distilled water

Examples 2-4
Compound 2 of Examples 2 to 4 was the same as Example 1 except that the monomer ratio in <Preparation of Compound 1> in Example 1 was changed to the monomer ratios described in Examples 2 to 4 of Table 1. ~ 4 were created.
Next, in the same manner as in Example 1, except that the aqueous solution of compound 2-4 (solid content 20%) was used instead of the aqueous solution of compound 1 (solid content 20%) in <Preparation of Pigment Dispersion 1>. Pigment dispersions 2 to 4 were prepared, and inks of Examples 2 to 4 were prepared using these in the same manner as in <Preparation of Ink 1>.

Example 5
The amount of NaOH 20% aqueous solution used in <Preparation of Compound 1> in Example 1 was changed from 1.2 parts to 0.8 parts, and the amount of distilled water was changed from 60.0 parts to 60.4 parts. Except for this point, the pigment dispersion 5 was prepared in the same manner as in Example 1, and using this, the ink of Example 5 was prepared in the same manner as in <Preparation of Ink 1>.

Example 6
The amount of NaOH 20% aqueous solution used in <Preparation of Compound 1> in Example 1 was changed from 1.2 parts to 0.5 parts, and the amount of distilled water was changed from 60.0 parts to 60.7 parts. Except for this point, a pigment dispersion 6 was prepared in the same manner as in Example 1, and using this, the ink of Example 6 was prepared in the same manner as in <Preparation of Ink 1>.

Examples 7 and 8
In the same manner as in Example 1, except that the neutralizing NaOH 20% aqueous solution used in <Preparation of Compound 1> in Example 1 was changed to LiOH (Example 7) and dimethylethanolamine (Example 8), Compounds 7 and 8 of Examples 7 and 8 were prepared.
Next, instead of the aqueous solution of compound 1 (solid content 20%) in <Preparation of Pigment Dispersion 1>, an aqueous solution of compounds 7 and 8 (solid content 20%) was used, and a NaOH 20% aqueous solution was converted to a LiOH 20% aqueous solution (Example 7). ), Or pigment dispersions 7 and 8 were prepared in the same manner as in Example 1 except that the solution was changed to a 20% aqueous solution of dimethylethanolamine (Example 8), and these were used to produce <Ink 1>. Thus, inks of Examples 7 and 8 were prepared.

Comparative Examples 1-3
<Preparation of the compound of Comparative Example 1>
A four-necked flask is equipped with a thermometer, stirrer, and reflux condenser, charged with 500 g of water and 15 g of aninium persulfate, and slowly added dropwise with stirring, 129 g of styrene and 171 g of acrylic acid under heating conditions of 80 to 90 ° C. did. The ratio (%) of styrene to acrylic acid is 43:57.
Subsequently, after reacting for 4 hours, the mixture was cooled and neutralized with a 20% NaOH aqueous solution, and distilled water was further added to adjust the solid content to 20%. A styrene-acrylic acid copolymer Na salt (Comparative Example) Of 1) was obtained.

<Preparation of the compound of Comparative Example 2>
An aqueous solution of a styrene-maleic acid copolymer Na salt (compound of Comparative Example 2) was obtained in the same manner as Comparative Example 1 except that the acrylic acid of Comparative Example 1 was changed to maleic acid.

<Preparation of the compound of Comparative Example 3>
In the preparation of Compound 1 of Example 1, a styrene-acrylic acid-acrylamide copolymer Na salt (compound of Comparative Example 3) was prepared in the same manner as in Example 1 except that maleic anhydride was changed to acrylic acid. An aqueous solution was obtained.

Subsequently, Example 1 was used except that the aqueous solution of the compounds of Comparative Examples 1 to 3 (solid content 20%) was used instead of the aqueous solution of compound 1 (solid content 20%) in <Preparation of Pigment Dispersion 1>. In the same manner, pigment dispersions and inks of Comparative Examples 1 to 3 were prepared.

Comparative Example 4
A pigment dispersion and ink of Comparative Example 4 were prepared in the same manner as in Example 1 except that Compound 1 was changed to naphthalenesulfonic acid formalin condensate.

Comparative Example 5
The pigment dispersion and ink of Comparative Example 5 were prepared in the same manner as in Example 1 except that the pH of Pigment Dispersion 1 was not adjusted (no NaOH 20% aqueous solution was added).

About each ink of the said Examples 1-8 and Comparative Examples 1-5, the storage stability was evaluated with the following method.
<Storage stability>
The initial viscosity of each ink liquid was measured. Next, 50 g of each ink solution was placed in a Nidec Denka company sample bottle SV-50 and sealed, and stored at 70 ° C. for 2 weeks, and then the viscosity after storage was measured. And the change rate was calculated according to the following formula, and the ranking was performed according to the following criteria. RE500 manufactured by Toyo Seiki Co., Ltd. was used as the viscometer. The results are shown in Table 1.
Rate of change (%) = [(viscosity after storage−initial viscosity) / initial viscosity] × 100

[Ranking criteria]
A: Change rate is less than 10% (good)
○: The rate of change is 10% or more and less than 15% (a level that causes no practical problems)
Δ: Change rate is 15% or more and less than 20% (problem level)
×: Change rate is 20% or more (very problematic level)

<Image density>
Each of the inks of Examples 1 to 8 and Comparative Examples 1 to 5 was filled in an ink pack for an ink jet printer IPSiO GX5000 manufactured by Ricoh, and a cartridge was prepared and mounted on the printer. This printer has the configuration shown in FIG.
Next, printing was performed on Xerox PPC paper: XEROX 4200 (non-smooth paper), and the printed image was measured with an Xrite densitometer 938. The results are shown in Table 1. Larger numbers are better.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Main body housing | casing 16 Gear mechanism 17 Subscanning motor 18 Carriage 18a Droplet discharge head 19 Platen 20 Cartridge 21 Guide shaft 22 Guide shaft 23 Timing belt 25 Gear mechanism 26 Main scanning motor 27 Gear mechanism

JP 2007-217508 A JP 2005-205847 A JP 2010-69805 A

Claims (5)

  A pigment dispersion containing a pigment, a dispersant and water, and an ink for inkjet recording containing a water-soluble organic solvent, the styrene-maleic anhydride-acrylamide copolymer salt as the dispersant, and An inkjet recording ink having a pH of 8.0 or more.   The ink for inkjet recording according to claim 1, wherein the copolymer salt is a Na salt.   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 3.   An image formed product printed using the ink for ink jet recording according to claim 1.

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