JP2015081276A - Ink for inkjet recording, and ink cartridge, production method of inkjet recording material, inkjet recording device, and ink recorded material using the ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink for inkjet recording, which gives high image density and shows good dispersion stability of a pigment and discharge stability as an ink.SOLUTION: The ink for inkjet recording comprises at least water, a water-soluble solvent, a pigment, and a copolymer containing a phosphonic acid group; and the copolymer containing a phosphonic acid group has at least a structural unit expressed by general formula (1) below and glycerin (meth)acrylate.

Description

  The present invention relates to an ink for ink jet recording, an ink cartridge using the ink, a method for producing an ink jet recorded material, an ink jet recording apparatus, and an ink recorded material.

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 method is a method of causing a small amount of ink to fly with pressure generated using bubbles generated by heat, piezo or static electricity, and to adhere to a recording medium such as paper, and to dry quickly, or recording medium In this method, an image is formed by penetrating into the printer, and its application has been expanded to personal and industrial printers and printing.

In the ink jet recording apparatus, a water-based ink using a water-soluble dye as a pigment is mainly used. However, the dye ink has a defect that it is inferior in weather resistance and water resistance. Therefore, in recent years, research on pigment inks using pigments instead of water-soluble dyes has been advanced. However, the pigment ink is still inferior in color development, ink ejection stability, and storage stability to the dye ink.
In addition, with the improvement of image quality improvement technology for OA printers, image density equivalent to that of dye ink is required for both pigment ink and plain paper as a recording medium. However, when plain paper is used as a recording medium, the pigment ink has a problem that the pigment density on the paper surface is lowered by penetrating into the paper and the image density is lowered.

  In recent years, demand for industrial applications has been increasing, and high-speed printing is desired. Ink jet printers equipped with line heads have been proposed along with high-speed printing. In order to increase the drying speed of the ink adhering to the recording medium for high-speed printing, a means is taken to accelerate drying by adding a penetrant to the ink and allowing water to penetrate into the recording medium. In addition to this, the penetrability of the pigment into the recording medium is increased, and the image density is further lowered.

Various methods have been proposed for improving the image density.
For example, Patent Document 1 discloses an ink used for recording on paper containing a water-soluble polyvalent metal salt. At this time, the ink includes (a) a pigment, (b) a functional group having no surface activity, a molecular weight of 150 or more and 10,000 or less, and having phosphoric acid as a basic skeleton in the molecular structure. And at least one compound having a phosphorus content ((P content / molecular weight) × 100) of 1.4 or more derived from a functional group selected from functional groups having phosphonic acid as a basic skeleton, b) The content (% by mass) of the compound is 1.5% by mass or more and 10.0% by mass or less based on the total mass of the ink.

In the method of Patent Document 1, the image density is not sufficiently improved on plain paper having a low content of water-soluble polyvalent metal salt. When a compound having a functional group selected from a functional group having a basic skeleton of phosphoric acid and a functional group having a basic skeleton of phosphonic acid is used, the image density is improved, but dispersion of the pigment in the ink is unstable. I found out that
That is, in the method of Patent Document 1, it is not possible to achieve both high image density and dispersion stability of the pigment as the ink.

An object of the present invention is to solve the above-described problems and achieve the following objects.
That is, an object of the present invention is to provide an ink for inkjet recording, which can obtain a high image density and has good dispersion stability and ejection stability of a pigment as an ink.

［式（１）中のＲ1は水素原子またはメチル基を表す。Ｒ2は炭素数１〜４のアルキル基を表す。Ｍ⁺は、プロトン、アルカリ金属イオンまたは有機アンモニウムイオンを表す。］

［式（２）中のＲ3は水素原子またはメチル基を表す。] Means for solving the above-mentioned problems are as follows. That is,
<1> An inkjet recording ink comprising at least water, a water-soluble solvent, a pigment, and a copolymer containing a phosphonic acid group, wherein the copolymer containing the phosphonic acid group is at least the following general An ink for inkjet recording, comprising at least a structural unit represented by the formula (1) and a structural unit represented by the following general formula (2).

[R1 in Formula (1) represents a hydrogen atom or a methyl group. R2 represents an alkyl group having 1 to 4 carbon atoms. M ⁺ represents a proton, an alkali metal ion or an organic ammonium ion. ]

[R3 in Formula (2) represents a hydrogen atom or a methyl group. ]

  According to the present invention, it is possible to provide an ink for ink jet recording which can obtain a high image density and has good dispersion stability and ejection stability of a pigment as an ink.

It is a schematic plan view for explaining an example of the ink cartridge of the present invention. FIG. 2 is a schematic plan view including a case (exterior) of the ink cartridge of the present invention shown in FIG. 1. 1 is a perspective view showing an example of a serial type ink jet recording apparatus of the present invention. FIG. 4 is a partially enlarged sectional view of the ink jet recording apparatus shown in FIG. 3. FIG. 4 is another partially enlarged sectional view of the ink jet recording apparatus shown in FIG. 3.

  The ink for ink-jet recording according to the present invention is an ink for ink-jet recording containing at least water, a water-soluble solvent, a pigment, and a copolymer containing a phosphonic acid group, wherein the copolymer is at least It has at least a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

［式（１）中のＲ1は水素原子またはメチル基を表す。Ｒ2は炭素数１〜４のアルキル基を表す。Ｍ⁺は、プロトン、アルカリ金属イオンまたは有機アンモニウムイオンを表す。］

［式（２）中のＲ3は水素原子またはメチル基を表す。]

[R1 in Formula (1) represents a hydrogen atom or a methyl group. R2 represents an alkyl group having 1 to 4 carbon atoms. M ⁺ represents a proton, an alkali metal ion or an organic ammonium ion. ]

[R3 in Formula (2) represents a hydrogen atom or a methyl group. ]

The structural unit of the formula (1) is hydrophilic, but has a characteristic that it exhibits hydrophobicity by binding to a polyvalent metal ion (particularly calcium ion). Therefore, when an ink containing a compound containing the formula (1) is used and an image is formed on a printing paper containing a polyvalent water-soluble metal salt, the polyvalent metal ions eluted from the paper to the ink The structural unit of the formula (1) becomes hydrophobic, and the pigment is entrapped and aggregated, so that the pigment remains on the paper surface and the image density is improved.
However, in the case of plain paper, the contained polyvalent metal salt is generally poorly water-soluble calcium carbonate, and the amount of calcium ions eluted into the ink is small. Therefore, a sufficient image density cannot be obtained on plain paper simply by including the structural unit of the formula (1).
As one of the methods for solving the above, it is conceivable to increase the constituent ratio of the formula (1) of the copolymer containing a phosphonic acid group. However, if the constituent ratio of the formula (1) is increased, the interaction between the phosphonic acid groups becomes stronger, or the gelation of the copolymer occurs and causes a decrease in the storage stability of the ink. Therefore, the composition ratio of formula (1) of the conventional copolymer containing phosphonic acid groups has to be less than 20% by mass.

In the present invention, by combining the structural unit of the formula (2) in addition to the structural unit of the formula (1), the affinity for the pigment is improved, the aggregation effect involving the pigment is improved, and the content of the water-soluble solvent is further increased. Storage stability was improved even with ink with a large amount of ink.
Further, gelation of the copolymer is less likely to occur, the constituent ratio of the formula (1) can be increased, and the reactivity with polyvalent metal ions (particularly calcium ions) can be improved.
Therefore, with the ink of the present invention, it has become possible to obtain a high image density even on general plain paper with a small amount of water-soluble polyvalent metal salt.

Next, the ink for ink jet recording according to the present invention, the ink cartridge using the ink, the method for producing the ink jet recorded material, the ink jet recording apparatus, and the ink recorded material will be described in more detail.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

<Ink for inkjet recording>
The ink for ink jet recording of the present embodiment (hereinafter sometimes referred to as “ink”) reacts with water, a water-soluble solvent, a pigment, and polyvalent metal ions (particularly calcium ions) in plain paper. And at least a copolymer that causes aggregation, and further contains other components as necessary.
The ink for inkjet recording according to the present invention causes aggregation when the copolymer lands on a recording medium such as plain paper and reacts with polyvalent metal ions contained in the plain paper, and the ink enters the paper. Is suppressed, and a high image density can be obtained.
In addition, the copolymer in which aggregation occurs by reacting with a polyvalent metal ion has at least the structural unit represented by the formula (1) and the structural unit represented by the formula (2) as described above. It is a copolymer.

  Hereinafter, the components constituting the ink jet recording ink of the present invention will be described in more detail.

(Copolymer containing phosphonic acid group)
The copolymer containing phosphonic acid groups used in the present invention reacts with polyvalent metal ions (particularly calcium ions) contained in plain paper when the ink for ink jet recording lands on a recording medium such as plain paper. And have the property of aggregating. By this function, it is possible to obtain a high image density by suppressing the penetration of the ink into the paper.
In the present invention, the phosphonic acid group-containing copolymer can be used as a pigment dispersant or additive, but particularly by using it as a pigment dispersant, the image density, storage stability, and ejection stability are further increased. Can provide good ink.

In the general formula (1), R1 represents either a hydrogen atom or a methyl group.
M ⁺ in the general formula (1) represents a proton, an alkali metal ion, or an organic ammonium ion, and is preferably ionized by neutralization with a base.
Examples of the base used for neutralization include inorganic alkalis such as alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; alkylamines such as mono, di or trimethylamine, mono, di or triethylamine Ethanolamine, diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, dimethylethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, trishydroxymethylaminomethane, 2-amino-2-ethyl- Alcohol amines such as 1,3-propanediol (AEPD); cyclic amines such as choline, morpholine, N-methylmonoformin, N-methyl-2-pyrrolidone, 2-pyrrolidone; water Of tetramethyl ammonium, tetraethyl ammonium hydroxide, organic ammonium hydroxide such as tetrabutylammonium hydroxide, and the like.
Among these, organic amines such as ethanolamine and dimethylethanolamine are preferable from the viewpoint of storage stability and ejection stability of the ink.

More than half of the M ⁺ is preferably ionized by neutralization with a base, and from the viewpoint of image density, storage stability, and ejection stability, it is particularly preferable that all are ionized by neutralization with a base.
In addition, the neutralization rate of the phosphonic acid group in the copolymer containing the phosphonic acid group obtained by the said neutralization process defines the value calculated | required with the following method as a neutralization rate in this invention.
When the compound represented by formula (3) is monomer 1,
Neutralization rate X (%) = (number of moles of base added x valence of base cation)
÷ (number of moles of monomer 1 contained in copolymer × 4) × 100
Number of moles of base added = amount of base added Yg ÷ molecular weight of base Number of moles of monomer 1 contained in copolymer
= Charge amount of monomer 1 Zg / Molecular weight of monomer 1 Therefore, the amount of base necessary to obtain the neutralization rate X% is: Base addition amount Yg = Neutralization rate X (%) x (Feed amount of monomer 1 Zg × 4)
X base molecular weight / (base cation valence x 100 x monomer 1 molecular weight)
It becomes.

The copolymer containing a phosphonic acid group includes structural units derived from other monomers in addition to the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2). be able to.
There is no restriction | limiting in particular as said other monomer, According to the objective, it can select suitably, For example, a polymerizable hydrophobic monomer, a polymerizable hydrophilic monomer, etc. are mentioned.

  The polymerizable hydrophobic monomer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include aromatics such as styrene, α-methylstyrene, 4-t-butylstyrene, and 4-chloromethylstyrene. Unsaturated ethylene monomer having an aromatic ring; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, dimethyl maleate, dimethyl itaconate, dimethyl fumarate, lauryl (meth) acrylate (C12), tridecyl (meth) acrylate (C13), tetradecyl (meth) acrylate (C14), pentadecyl (meth) acrylate (C15), hexadecyl (meth) acrylate (C16), heptadecyl (meth) acrylate (C17), nonadecyl (meth) acrylate (C19), (meth) acrylic acid ray Alkyl (meth) acrylates such as syl (C20), heicosyl (meth) acrylate (C21), docosyl (meth) acrylate (C22); 1-heptene, 3,3-dimethyl-1-pentene, 4,4 -Dimethyl-1-pentene, 3-methyl-1-hexene, 4-methyl-1-hexene, 5-methyl-1-hexene, 1-octene, 3,3-dimethyl-1-hexene, 3,4-dimethyl -1-hexene, 4,4-dimethyl-1-hexene, 1-nonene, 3,5,5-trimethyl-1-hexene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene , 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicocene, 1-docose, etc. Monomer, and the like. These may be used individually by 1 type and may use 2 or more types together.

  The polymerizable hydrophilic monomer is not particularly limited and may be appropriately selected depending on the purpose. For example, (meth) acrylic acid or a salt thereof, maleic acid or a salt thereof, monomethyl maleate, itaconic acid, Anionic unsaturated ethylene monomers such as monomethyl itaconic acid, fumaric acid, 4-styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid; (meth) acrylic acid-2-hydroxyethyl, diethylene glycol mono (meth) acrylate, Triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, (meth) acrylamide, N-methylol (meth) acrylamide, N-vinylformamide, N-vinylacetamide N- vinylpyrrolidone, acrylamide, N, N- dimethylacrylamide, N-t-butylacrylamide, N- octyl acrylamide, nonionic ethylenically unsaturated monomers such as N-t-octyl acrylamide, and the like. These may be used individually by 1 type and may use 2 or more types together.

The polymerization method of the copolymer containing a phosphonic acid group used in the present invention is not particularly limited, and a known polymerization method can be used.
For example, a thermometer, a stirrer, and a nitrogen introduction tube are installed in a four-necked flask, and a solvent, a monomer represented by the following general formula (3), and a monomer represented by the following general formula (4) are used as necessary. Then, a polymerization initiator and a chain transfer agent are added, and polymerization can be performed at room temperature to 150 ° C.
The viscosity of the copolymer containing phosphonic acid groups can be adjusted by changing the molecular weight, and the monomer concentration, polymerization initiator amount, polymerization temperature, and polymerization time during polymerization may be changed.

As the synthesis method, various known synthesis methods such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like can be used. However, since the polymerization operation and the adjustment of the molecular weight are easy, a radical polymerization initiator is used. The method used is preferred.
As the radical polymerization initiator, those generally used can be used, and specifically, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, peroxyesters, cyano series Azobisisobutyronitrile, azobis (2-methylbutyronitrile), azobis (2,2′-isovaleronitrile), non-cyano dimethyl-2,2′-azobisisobutyrate, and the like. . Organic peroxides and azo compounds that can easily control the molecular weight and have a low decomposition temperature are preferable, and azo compounds are more preferable. As for the usage-amount of a polymerization initiator, 1-10 mass% is preferable with respect to the total mass of a polymerizable monomer.
Further, in order to adjust the molecular weight of the copolymer containing a phosphonic acid group, such as mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, dodecyl mercaptan, 1-dodecanethiol, thioglycerol, etc. An appropriate amount of chain transfer agent may be added to the polymerization system.
A preferable polymerization temperature is 50 to 150 ° C., and a preferable polymerization time is 3 to 48 hours.

The copolymer containing a phosphonic acid group of the present invention is synthesized using at least a monomer represented by the general formula (3) and a monomer represented by the following general formula (4) as starting materials. It is preferable that a part or all of the phosphonic acid group of the coalescence is neutralized with a base selected from alkali metals or organic amines.
Examples of the method for adding the neutralizing agent include a method in which a copolymer containing a phosphonic acid group obtained by the above production method and a neutralizing agent are mixed in a solution. The copolymer containing phosphonic acid groups is dissolved in an organic solvent or water, and a neutralizing agent is added directly to the solution, or a solution in which the neutralizing agent is dissolved in an organic solvent or water is added and stirred. Then, the copolymer containing the phosphonic acid group neutralized with the base is obtained by removing the solvent.
After completion of the polymerization reaction, the produced copolymer containing a phosphonic acid group can be isolated from the reaction solution by a conventionally known method such as reprecipitation or solvent distillation. In addition, a copolymer containing a phosphonic acid group can be purified by repeating reprecipitation or removing unreacted monomers and low molecular weight components by membrane separation, chromatographic methods, extraction methods, and the like.
In the present invention, a copolymer in which part or all of the phosphonic acid groups are neutralized is also referred to as a copolymer containing phosphonic acid groups.

［式（３）中のＲ4は水素原子またはメチル基を表す。Ｒ5は炭素数１〜４のアルキル基を表す。］

［式（４）中のＲ6は水素原子またはメチル基を表す。] The copolymer containing a phosphonic acid group of the present invention is synthesized using at least a monomer represented by the following general formula (3) and a monomer represented by the following general formula (4) as starting materials.

[R4 in Formula (3) represents a hydrogen atom or a methyl group. R5 represents an alkyl group having 1 to 4 carbon atoms. ]

[R6 in Formula (4) represents a hydrogen atom or a methyl group. ]

Examples of the monomer represented by the formula (3) include monomers of the following (formula 3-1) to (formula 3-2). In the copolymer, R2 of the structural unit represented by the general formula (1) represents an alkyl group having 1 to 4 carbon atoms. Examples of the monomer represented by the general formula (3) include those in which R5 is an alkyl group having 2 to 4 carbon atoms in addition to the following (formula 3-1) to (formula 3-2). The effect is obtained.
Examples of the monomer represented by the formula (4) include monomers of the following (formula 4-1) to (formula 4-2).
In the copolymer, R3 of the structural unit represented by the general formula (2) is preferably a methyl group, and the monomer represented by the formula (4) is represented by (formula 4-2). Monomers are preferred.

前記（式３−１）、前記（式３−２）、で表されるモノマーは、例えば、特開昭５８−２２２０９５号公報に記載の方法で合成することができる。

The monomers represented by (Formula 3-1) and (Formula 3-2) can be synthesized, for example, by the method described in JP-A No. 58-222095.

  In the copolymer containing a phosphonic acid group of the present invention, when the content of the structural unit represented by the formula (1) is low, the reactivity with calcium ions eluted from the recording medium decreases, and the image density Tend to decrease. In that respect, the content is preferably 10 to 60% by mass, and more preferably 15 to 50% by mass. When the content is 60% by mass or less, the dispersion stability of the pigment is improved, the viscosity of the ink is stabilized, and the storage stability and ejection stability are improved. That is, when the content is 10 to 60% by mass, it is possible to achieve both high image density improvement, pigment dispersion stability in ink, and ejection stability during printing.

  The viscosity (25 ° C.) of a 10% by weight solid content aqueous solution of the copolymer containing phosphonic acid groups of the present invention is preferably in the range of 1.5 to 30.0 mPa · s, and is preferably 1.7 to 18.0 mPa.s. -More preferably, it is in the range of s. When the viscosity is 1.5 mPa · s or more, the image density is high and good. This is presumably because the pigment aggregating action is improved when it reacts with polyvalent metal ions eluted from the recording medium. On the other hand, when the viscosity is 30.0 mPa · s or less, the dispersion stability of the pigment is improved, and the viscosity of the pigment dispersion and the ink is not increased and the storage stability is improved.

What is necessary is just to select suitably the quantity of the copolymer in the case of using the copolymer used for this invention as a dispersing agent by the kind of pigment (pigment), and is 0.005-5 mass parts with respect to 1 mass part of pigments. is there. Preferably it is 0.01-2 mass parts with respect to 1 mass part of pigment, More preferably, it is 0.02-0.5 mass part with respect to 1 mass part of pigment. When it is in the range of 0.005 to 5 parts by mass, the dispersibility of the pigment is improved and the aging stability of the ink is improved, and when it is in the range of 0.01 to 2 parts by mass, these effects are further enhanced. In particular, in the range of 0.02 to 0.5 parts by mass, the temporal stability of the ink is further improved.
Moreover, you may use together the dispersing agent described later with a copolymer in the range which does not impair the said effect.

(water)
As water used in the present invention, pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water can be used.
The water content is preferably 20 to 60% by mass with respect to the total amount of ink.

(Water-soluble solvent)
The water-soluble solvent used in the present invention is necessary for improving ejection stability by providing a moisturizing effect in the ink composition. The content is preferably 10 to 50% by mass with respect to the total amount of ink. If the content is less than 10% by mass, the ink easily evaporates, and thickened ink may be clogged due to evaporation of the ink in the ink supply system in the inkjet recording apparatus. If the content is more than 50% by mass, clogging of thickened ink is less likely to occur in the ink jet recording apparatus, but it is necessary to reduce the amount of solids such as pigments and resins in order to make the ink have a desired viscosity. In this case, the image density of the recorded matter may be lowered.

Examples of the water-soluble solvent used in the present invention include, but are not limited to, the following. For example, ethylene glycol, diethylene glycol, 1,3-butanediol, 3-methyl-1,3-butyl glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerin 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,2,4-butanetriol, 1,2,3 -Polyhydric alcohols such as butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetra Polyhydric alcohol alkyl ethers such as tylene glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam, γ-butyrolactone, amides such as formamide, N-methylformamide, N, N-dimethylformamide , Amines such as monoethanolamine, diethanolamine, triethylamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, thiodiethanol, propylene carbonate, ethylene carbonate, etc. That.
These water-soluble solvents can be used alone or in combination of two or more. Among these, the inclusion of 1,3-butanediol, diethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol and / or glycerin is excellent in preventing discharge failure due to moisture evaporation. Effect. In particular, glycerin is preferably included.

(Pigment)
The content of the pigment used in the present invention in the recording ink is preferably 0.1% by mass or more and 20.0% by mass or less. The volume average particle diameter (D50) of the pigment is preferably 150 nm or less.
Here, the volume average particle diameter (D50) of the pigment is measured by a dynamic light scattering method using Microtrac UPA manufactured by Nikkiso Co., Ltd. in an environment of 23 ° C. and 55% RH.
There is no restriction | limiting in particular as these pigments, According to the objective, it can select suitably, For example, any of an inorganic pigment and an organic pigment may be sufficient. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, metal powder, and carbon black. Among these, carbon black is preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

Examples of the organic pigment include azo pigments, azomethine pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable.
Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, rhodamine B lake pigments, and the like. It is done. Examples of the dye chelates include basic dye chelates and acidic dye chelates.

Examples of black materials include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, copper, iron (CI pigment black 11), titanium oxide, and the like. And organic pigments such as aniline black (CI Pigment Black 1).
As the carbon black, a furnace method, a carbon black produced by the channel method, primary particle diameter of, 15Nm～40nm, specific surface area by BET ^{method, 50m 2 / g~300m 2 / g} , DBP oil absorption amount 40ml / 100 g to 150 ml / 100 g, those having a volatile content of 0.5% to 10% and a pH value of 2 to 9 are preferred.
A commercially available product can be used as the carbon black. Examples of commercially available products include No. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (all manufactured by Mitsubishi Chemical Corporation); Raven700, 5750, 5250, 5000, 3500, 1255 (all manufactured by Columbia); Regal400R, 330R, 660R, Mogu L, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (all manufactured by Cabot); Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, and 4 (all manufactured by Degussa).

  The pigment that can be used for the yellow ink for color is not particularly limited and can be appropriately selected according to the purpose. I. Pigment yellow 1, C.I. I. Pigment yellow 2, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 174, C.I. I. Pigment yellow 180, and the like.

  The pigment that can be used in the magenta ink for color is not particularly limited and may be appropriately selected depending on the intended purpose. I. Pigment red 5, C.I. I. Pigment red 7, C.I. I. Pigment red 12, C.I. I. Pigment red 48 (Ca), C.I. I. Pigment red 48 (Mn), C.I. I. Pigment red 57 (Ca), C.I. I. Pigment red 57: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 146, C.I. I. Pigment red 168, C.I. I. Pigment red 176, C.I. I. Pigment red 184, C.I. I. Pigment red 185, C.I. I. Pigment red 202, pigment violet 19, and the like.

  The pigment that can be used for the cyan ink for the color is not particularly limited and may be appropriately selected according to the purpose. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 3, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15:34, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. Pigment blue 60, C.I. I. Pigment blue 63, C.I. I. Pigment blue 66; C.I. I. Bat Blue 4, C.I. I. Bat Blue 60 and the like.

In addition, the pigment contained in each ink used in the present invention may be newly produced for the present invention.
By using Pigment Yellow 74 as the yellow pigment, Pigment Red 122, Pigment Bio Red 19 as the magenta pigment, and Pigment Blue 15: 3 as the cyan pigment, an ink with excellent color tone and light fastness and balanced can be obtained. Can be obtained.
Furthermore, the pigment used in the present invention may be a grafted or encapsulated product coated with a surfactant such as a dispersant or a resin. More preferably, the coalescence is used as a dispersant.
Moreover, you may use together the pigment mentioned above in the range which does not impair an effect.

(Other ingredients)
There is no restriction | limiting in particular as another component used for the composition of the ink for inkjet recording of this invention, It can select suitably as needed. Examples of other components include a dispersant, a pH adjuster, a water-dispersible resin, an antiseptic / antifungal agent, a chelating reagent, a rust inhibitor, an antioxidant, an ultraviolet absorber, an oxygen absorber, and a light stabilizer. Is mentioned.

(Dispersant)
As the dispersant, a copolymer containing a phosphonic acid group of the present invention is preferable, but various surfactants and polymers such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant are used. Also included are types of dispersants. 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 Examples thereof include acetylene glycol surfactants.

(PH adjuster)
The pH adjuster is not particularly limited as long as the pH can be adjusted to 8.5 to 11 and preferably 9 to 11 without adversely affecting the ink jet ink to be prepared. It can be selected appropriately. For example, alcohol amines, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates, and the like can be given. If the pH is less than 8.5 or more than 11, the amount of the ink-jet head or ink supply unit that melts out is large, and problems such as ink deterioration, leakage, and ejection failure may occur. When it is less than 8.5, the ink pH may decrease during storage of the ink, and the polymer fine particles may aggregate due to an increase in the particle diameter.
The pH can be measured by, for example, a pH meter HM-30R (manufactured by TOA-DKK).

  Examples of the 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.

(Water dispersible resin)
The water-dispersible resin has excellent film-forming properties (image formability), high water repellency, high water resistance, and high weather resistance, and has high water resistance and high image density (high color development). Useful for.
Specific examples of the water-dispersible resin include condensation-type synthetic resins, addition-type synthetic resins, natural polymer compounds, and the like.
Examples of the condensed synthetic resin include polyester resin, polyurethane resin, polyepoxy resin, polyamide resin, polyether resin, poly (meth) acrylic resin, acrylic-silicone resin, and fluorine-based resin. Examples of the addition type synthetic resin include polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, and the like. Examples of the natural polymer compound include celluloses, rosins, and natural rubber.
Among these, polyurethane resin fine particles, acrylic-silicone resin fine particles, and fluorine-based resin fine particles are particularly preferable.

The volume average particle diameter (D50) of the water-dispersible resin is related to the viscosity of the dispersion, and for the same composition, the viscosity at the same solid content increases as the particle diameter decreases. The volume average particle diameter (D50) of the water-dispersible resin is preferably 50 nm or more so that the ink does not have an excessively high viscosity. Further, when the particle size is several tens of μm, it becomes larger than the nozzle opening of the ink jet head and cannot be used. If particles having a large particle diameter are present in the ink even though they are smaller than the nozzle opening, the ejection stability is deteriorated. Therefore, the volume average particle diameter (D50) is more preferably 200 nm or less in order not to disturb the ink ejection stability.
Here, the volume average particle diameter (D50) of the water-dispersible resin is measured by a dynamic light scattering method using Microtrac UPA manufactured by Nikkiso Co., Ltd. in an environment of 23 ° C. and 55% RH.

The water-dispersible resin has a function of fixing the water-dispersed pigment on the paper surface, and is preferably formed into a film at room temperature to improve the fixability of the color material. Therefore, it is preferable that the minimum film-forming temperature (MFT) of the water-dispersible resin is 30 ° C. or less.
Further, when the glass transition temperature of the water-dispersible resin is -40 ° C. or lower, the resin film becomes more viscous and the printed matter is tacky. Therefore, the water-dispersible resin has a glass transition temperature of −30 ° C. or higher. It is preferable. When the water-dispersible resin is added, the content in the inkjet ink is preferably 1 to 15% by mass and more preferably 2 to 7% by mass in terms of solid content.

(Antiseptic and antifungal agent)
Examples of the antiseptic / antifungal agent include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, sodium pentachlorophenol, and the like.

(Chelating reagent)
Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like.

(Rust inhibitor)
Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

(Antioxidant)
Examples of the antioxidant include phenolic antioxidants (including hindered phenolic antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.

(UV absorber)
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.

(Inkjet ink manufacturing method)
The ink-jet ink of this embodiment is obtained by dispersing or dissolving water, a water-soluble solvent, a pigment, a copolymer containing a phosphonic acid group, and other components in an aqueous medium as required, and further if necessary. Produced by stirring and mixing.
The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, etc., and stirring and mixing are performed by a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like. be able to.

There is no restriction | limiting in particular as a physical property of the inkjet ink of this invention, According to the objective, it can select suitably, For example, it is preferable that viscosity, surface tension, etc. are the following ranges.
The viscosity of the inkjet ink at 25 ° C. is preferably 3 mPa · s to 20 mPa · s. By setting the ink viscosity to 3 mPa · s or more, the effect of improving the printing density and the character quality can be obtained. On the other hand, by suppressing the ink viscosity to 20 mPa · s or less, it is possible to ensure the discharge performance.
The viscosity can be measured at 25 ° C. using, for example, a viscometer (RE500L, manufactured by Toki Sangyo Co., Ltd.).
The surface tension of the inkjet ink is preferably 40 mN / m or less at 25 ° C. When the surface tension exceeds 40 mN / m, leveling of the ink on the recording medium is difficult to occur and the drying time may be prolonged.

(ink cartridge)
The ink cartridge of the present invention accommodates the ink for ink jet recording of the present invention in a container, and can also constitute other members appropriately selected as necessary.
The shape, structure, size, and material of the container are not particularly limited and can be appropriately selected according to the purpose. Preferred examples include those having at least an ink bag formed of an aluminum laminate film, a resin film, or the like.

  One embodiment of the ink cartridge of the present invention will be described with reference to FIGS. FIG. 1 is a schematic plan view for explaining an example of the ink cartridge of the present invention. FIG. 2 is a schematic plan view including a case (exterior) of the ink cartridge of FIG.

  As shown in FIG. 1, the ink cartridge 200 is filled into the ink bag 241 from the ink inlet 242 and exhausted, and then the ink inlet 242 is closed by fusion. In use, the needle of the apparatus main body is pierced into the ink discharge port 243 made of a rubber member and supplied to the apparatus. The ink bag 241 is formed of a packaging member such as a non-permeable aluminum laminate film. As shown in FIG. 2, the ink bag 241 is usually housed in a plastic cartridge case 244 and is detachably mounted on various ink jet recording apparatuses.

(Inkjet recording apparatus and inkjet recording method)
The ink jet recording apparatus of the present invention has at least ink ejecting means for recording the image on the recording medium by ejecting the ink for ink jet recording of the present invention from the recording head, and other means appropriately selected as necessary. , For example, comprising stimulus generating means, control means and the like.
The ink jet recording method using the ink of the present invention includes at least an ink flying process, and further includes other processes appropriately selected as necessary, for example, a stimulus generation process, a control process, and the like.
The ink jet recording method using the ink of the present invention can be preferably carried out by the ink jet recording apparatus of the present invention, and the ink flying step can be suitably carried out by the ink flying means. Moreover, the said other process can be suitably performed by the said other means.
The method for producing an inkjet recorded product of the present invention includes an ink flying process of recording an image on a recording medium by applying a stimulus to the ink for inkjet recording of the present invention via an ink flying means and causing the ink to fly from a recording head. Including at least.

The ink flying step is a step of forming an image by applying a stimulus to the ink jet ink of the present invention and causing the ink jet ink to fly.
The ink flying means is means for forming an image by applying a stimulus to the ink-jet ink of the present invention and causing the ink-jet ink to fly. The ink flying means is not particularly limited, and examples thereof include various nozzles for ejecting ink.

  The stimulus can be generated, for example, by the stimulus generating means, and the stimulus is not particularly limited and can be appropriately selected according to the purpose, such as heat (temperature), pressure, vibration, light, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, heat and pressure are preferable. Examples of the stimulus generating means include a superheater, a pressurizer, a piezoelectric element, a vibration generator, an ultrasonic oscillator, and a light. Specifically, a piezoelectric actuator such as a piezoelectric element such as a piezoelectric element, a thermal actuator that uses a phase change due to liquid film boiling using an electrothermal transducer such as a heating resistor, a shape that uses a metal phase change due to a temperature change Memory alloy actuators, electrostatic actuators using electrostatic force, and the like can be mentioned.

  There is no particular limitation on the mode of the ink flying, and it varies depending on the type of the stimulus. For example, when the stimulus is “heat”, the thermal energy corresponding to the recording signal is output to the ink in the recording head. For example, using a thermal head or the like, generating bubbles in the ink by the thermal energy, and ejecting and ejecting the ink as droplets from the nozzle holes of the recording head by the pressure of the bubbles. It is done. Further, when the stimulus is “pressure”, for example, by applying a voltage to a piezoelectric element bonded to a position called a pressure chamber in an ink flow path in the recording head, the piezoelectric element bends and the volume of the pressure chamber is increased. And a method of ejecting and ejecting the ink as droplets from the nozzle holes of the recording head.

  The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

Here, one aspect of carrying out the ink jet recording method of the present invention by the ink jet recording apparatus of the present invention will be described with reference to the drawings.
FIG. 3 is a perspective view showing an example of the ink jet recording apparatus of the present invention.
The ink jet recording apparatus shown in FIG. 3 stocks an apparatus main body 101, a paper feed tray 102 for loading paper loaded on the apparatus main body 101, and paper on which an image is recorded (formed) mounted on the apparatus main body 101. A paper discharge tray 103 and an ink cartridge loading unit 104 protruding forward from the front surface 112 and lower than the upper cover 111 are provided at one end of the front surface 112 of the apparatus main body 101. On the upper surface of the ink cartridge loading unit 104, an operation unit 105 such as operation keys and a display is arranged. The ink cartridge loading unit 104 has a front cover 115 that can be opened and closed for attaching and detaching the ink cartridge 200.

  As shown in FIGS. 4 and 5 (partially enlarged sectional view of the ink jet recording apparatus shown in FIG. 3), a guide which is a guide member horizontally mounted on left and right side plates (not shown) is provided in the apparatus main body 101. The carriage 133 is slidably held in the main scanning direction by the rod 131 and the stay 132, and is moved and scanned in the direction of the arrow as shown in FIG. 5 by the main scanning motor.

The carriage 133 is provided with a recording head 134 composed of four inkjet recording heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.
Examples of the ink jet recording head constituting the recording head 134 include a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase caused by a temperature change. A shape memory alloy actuator using a change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for ejecting ink can be used. In addition, the carriage 133 is equipped with a sub tank 135 for each color for supplying ink of each color to the recording head 134. The sub tank 135 is supplied with the ink from the ink cartridge 200 of the present invention loaded in the ink cartridge loading section 104 via an ink supply tube (not shown) and is replenished.

On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 102, a half-moon roller (feeding) that separates and feeds the paper 142 from the paper stacking unit 141 one by one. A separation pad 144 made of a material having a large coefficient of friction is provided facing the paper roller 143) and the paper feed roller 143, and the separation pad 144 is urged toward the paper feed roller 143 side.
As a transport unit for transporting the paper 142 fed from the paper feed unit below the recording head 134, a transport belt 151 for transporting the paper 142 by electrostatic adsorption and a guide 145 from the paper feed unit. The counter roller 152 for transporting the paper 142 fed via the transport belt 151 with the transport belt 151 and the paper 142 fed substantially vertically upward are changed by approximately 90 ° so as to follow the transport belt 151. For this purpose, a conveyance guide 153 and a tip pressure roller 155 urged toward the conveyance belt 151 by a pressing member 154 are provided.

In addition, a charging roller 156 that is a charging unit for charging the surface of the conveyance belt 151 is provided. The conveyance belt 151 is an endless belt, is stretched between the conveyance roller 157 and the tension roller 158, and can circulate in the belt conveyance direction. The transport belt 151 includes, for example, a surface layer serving as a sheet adsorbing surface formed of a resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), and the surface layer. It has a back layer (medium resistance layer, earth layer) that is made of the same material and has resistance controlled by carbon. On the back side of the conveyance belt 151, a guide member 161 is arranged corresponding to a printing area by the recording head 134.
Note that, as a paper discharge unit for discharging the paper 142 recorded by the recording head 134, a separation claw 171 for separating the paper 142 from the conveyance belt 151, a paper discharge roller 172, and a paper discharge roller 173 are provided. The paper discharge tray 103 is disposed below the paper discharge roller 172.

A double-sided paper feeding unit 181 is detachably mounted on the back surface of the apparatus main body 101.
The double-sided paper feeding unit 181 takes in the paper 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 152 and the transport belt 151. A manual paper feed unit 182 is provided on the upper surface of the duplex paper feed unit 181.

  In this ink jet recording apparatus, the paper 142 is separated and fed one by one from the paper feed unit, and the paper 142 fed substantially vertically upward is guided by the guide 145 and between the transport belt 151 and the counter roller 152. It is sandwiched and conveyed. Further, the leading end is guided by the conveying guide 153 and pressed against the conveying belt 151 by the leading end pressure roller 155, and the conveying direction is changed by approximately 90 °. At this time, the conveying belt 151 is charged by the charging roller 156, and the sheet 142 is electrostatically attracted to the conveying belt 151 and conveyed. Therefore, by driving the recording head 134 according to the image signal while moving the carriage 133, ink droplets are ejected onto the stopped paper 142 to record one line, and after the paper 142 is conveyed by a predetermined amount, Record the next line.

  Upon receiving a recording end signal or a signal that the trailing edge of the sheet 142 has reached the recording area, the recording operation is terminated and the sheet 142 is discharged onto the discharge tray 103. When the ink remaining amount near end in the sub tank 135 is detected, a required amount of ink is supplied from the ink cartridge 200 to the sub tank 135.

In this ink jet recording apparatus, when the ink in the ink cartridge 201 of the present invention is used up, the casing of the ink cartridge 200 can be disassembled and only the ink bag inside can be replaced. Further, the ink cartridge 200 can supply ink stably even when the ink cartridge 200 is installed vertically and has a front loading configuration. Therefore, the ink cartridge 200 is installed even when the upper portion of the apparatus main body 101 is closed, for example, when stored in a rack, or when an object is placed on the upper surface of the apparatus main body 101. Can be easily exchanged.
In addition, although it demonstrated in the example applied to the serial type (shuttle type) inkjet recording device which a carriage scans, it can apply similarly to the line type inkjet recording device provided with the line type head.

  The ink jet recording apparatus of the present invention can be applied to various types of recording by the ink jet recording method, and is particularly preferably applied to, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like. Can do.

(Ink record)
The ink recorded matter recorded by the ink jet recording method of the present invention is the ink recorded matter of the present invention. That is, the ink recorded matter of the present invention has an image recorded with the ink jet recording ink of the present invention on a recording medium (recording medium).
The recording medium is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include plain paper, coated paper for printing, glossy paper, special paper, cloth, film, and OHP sheet. It is done. These may be used individually by 1 type and may use 2 or more types together. Among these, at least one of plain paper and coated paper for printing is preferable. The plain paper is advantageous in that it is inexpensive. The coated paper for printing is advantageous in that it provides a smooth glossy image at a relatively low cost as compared with glossy paper. However, the image density is low and the drying property is poor, so that it is generally not preferable for use in inkjet.

The ink of the present invention is preferably used for paper having an amount of Ca ions eluted from the paper of 1.0 × 10 ^{−5 to} 5.0 × 10 ⁻⁴ [g / g]. When the Ca ion amount is 1.0 × 10 ⁻⁵ [g / g] or more, the effect of improving the image density by reaction aggregation with the pigment dispersant is improved. In addition, when the Ca ion amount is 5.0 × 10 ⁻⁴ [g / g] or less, the penetration of the ink into the paper is not inhibited, so that the drying property of the ink is improved, and the scratch resistance and the marker resistance are also improved. improves.
For example, the amount of Ca ions of MyPaper (plain paper manufactured by Ricoh Co., Ltd.) is 4.3 × 10 ⁻⁴ [g / g].
That is, the ink of the present invention can be used with improved image density and dryness even on plain paper and coated paper for printing.
The ink recorded matter of the present invention has high image quality, no bleeding, excellent stability over time, and can be suitably used for various purposes as a material on which various prints or images are recorded.

The amount of Ca ions eluted from the paper is calculated by the following method.
That is, the paper is cut into 2.5 cm (± 0.5 cm) × 3.5 cm (± 0.5 cm) square pieces of paper. 16 g of the cut paper piece is immersed in 200 g of high-purity water at 25 ° C. for 40 hours. High purity water (immersion liquid) after dipping a piece of paper is filtered through a 0.8 μm cellulose acetate filter (manufactured by Advantech) to remove foreign substances such as paper dust, and then CaP contained in the immersion liquid is analyzed by ICP emission spectroscopy. Quantify by instrument. The Ca ion concentration [ppm] obtained here is multiplied by 200 g, which is the weight of high-purity water, and is further divided by 16 g, which is the weight of the immersed paper. The amount of Ca ions eluted from the paper [g / g ] Is calculated.

［式（１）中のＲ1は水素原子またはメチル基を表す。Ｒ2は炭素数１〜４のアルキル基を表す。Ｍ⁺は、プロトン、アルカリ金属イオンまたは有機アンモニウムイオンを表す。］

［式（２）中のＲ3は水素原子またはメチル基を表す。]
（２）前記ホスホン酸基を含む共重合体における一般式（１）で表される構造単位の含有率が１０質量％〜６０質量％であることを特徴とする前記（１）に記載のインクジェット記録用インク。
（３）前記ホスホン酸基を含む共重合体の固形分１０質量％水溶液の粘度が１．５〜３０．０ｍＰａ・ｓであることを特徴とする前記（１）または（２）に記載のインクジェット記録用インク。
（４）前記ホスホン酸基を含む共重合体の一般式（２）で表される構造単位のＲ3がメチル基であることを特徴とする前記（１）〜（３）のいずれかに記載のインクジェット記録用インク。
（５）前記ホスホン酸基を含む共重合体の一般式（１）で表される構造単位のＭ⁺が有機アンモニウムイオンであることを特徴とする前記（１）〜（４）のいずれかに記載のインクジェット記録用インク。
（６）少なくとも水と、水溶性溶剤と、顔料と、ホスホン酸基を含む共重合体と、を含有するインクジェット記録用インクであって、
前記ホスホン酸基を含む共重合体が下記一般式（３）で表されるモノマーと、下記一般式（４）で表されるモノマーとを少なくとも出発物質として合成されることを特徴とするインクジェット記録用インク。

［式（３）中のＲ4は水素原子またはメチル基を表す。Ｒ5は炭素数１〜４のアルキル基を表す。］

［式（４）中のＲ6は水素原子またはメチル基を表す。]
（７）前記水溶性溶剤として少なくともグリセリンを含むことを特徴とする前記（１）〜（６）のいずれかに記載のインクジェット記録用インク。
（８）前記ホスホン酸基を含む共重合体を分散剤とすることを特徴とする前記（１）〜（７）のいずれかに記載のインクジェット記録用インク。
（９）前記（１）〜（８）のいずれかに記載のインクジェット記録用インクを容器中に収容してなることを特徴とするインクカートリッジ。
（１０）前記（１）〜（８）のいずれかに記載のインクジェット記録用インクにインク飛翔手段を介して刺激を印加し、記録ヘッドから該インクを飛翔させて記録媒体に画像を記録するインク飛翔工程を少なくとも含むことを特徴とするインクジェット記録物の製造方法。
（１１）前記（１）〜（８）のいずれかに記載のインクジェット記録用インクを記録ヘッドから飛翔させて記録媒体に画像を記録するインク飛翔手段を有することを特徴とするインクジェット記録装置。
（１２）前記（１）〜（８）のいずれかに記載のインクジェット記録用インクにより記録された画像を記録媒体上に有してなることを特徴とするインク記録物。 Further, the present invention relates to the following inkjet recording ink (1), and includes the following (2) to (12) as embodiments.
(1) An inkjet recording ink containing at least water, a water-soluble solvent, a pigment, and a copolymer containing a phosphonic acid group,
The inkjet recording ink, wherein the copolymer containing a phosphonic acid group has at least a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2): .

[R1 in Formula (1) represents a hydrogen atom or a methyl group. R2 represents an alkyl group having 1 to 4 carbon atoms. M ⁺ represents a proton, an alkali metal ion or an organic ammonium ion. ]

[R3 in Formula (2) represents a hydrogen atom or a methyl group. ]
(2) The inkjet according to (1), wherein the content of the structural unit represented by the general formula (1) in the copolymer containing the phosphonic acid group is 10% by mass to 60% by mass. Recording ink.
(3) The inkjet according to (1) or (2) above, wherein a viscosity of a 10% by mass solid content aqueous solution of the phosphonic acid group-containing copolymer is 1.5 to 30.0 mPa · s. Recording ink.
(4) The copolymer according to any one of (1) to (3), wherein R3 of the structural unit represented by the general formula (2) of the copolymer containing a phosphonic acid group is a methyl group. Ink for ink jet recording.
(5) In any one of the above (1) to (4), M ^{+ of the} structural unit represented by the general formula (1) of the copolymer containing a phosphonic acid group is an organic ammonium ion. The ink for inkjet recording as described.
(6) An inkjet recording ink containing at least water, a water-soluble solvent, a pigment, and a copolymer containing a phosphonic acid group,
The inkjet recording characterized in that the copolymer containing a phosphonic acid group is synthesized using at least a monomer represented by the following general formula (3) and a monomer represented by the following general formula (4) as starting materials. For ink.

[R4 in Formula (3) represents a hydrogen atom or a methyl group. R5 represents an alkyl group having 1 to 4 carbon atoms. ]

[R6 in Formula (4) represents a hydrogen atom or a methyl group. ]
(7) The ink for inkjet recording according to any one of (1) to (6), wherein the water-soluble solvent contains at least glycerin.
(8) The ink for inkjet recording according to any one of (1) to (7), wherein a copolymer containing the phosphonic acid group is used as a dispersant.
(9) An ink cartridge comprising the ink-jet recording ink according to any one of (1) to (8) contained in a container.
(10) Ink for recording an image on a recording medium by applying a stimulus to the ink for ink jet recording according to any one of (1) to (8) via an ink flying unit and causing the ink to fly from the recording head. A method for producing an ink-jet recorded matter, comprising at least a flying step.
(11) An ink jet recording apparatus comprising ink ejecting means for ejecting the ink for ink jet recording according to any one of (1) to (8) from a recording head to record an image on a recording medium.
(12) An ink recorded matter comprising an image recorded with the ink for ink jet recording according to any one of (1) to (8) on a recording medium.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further, this invention is not limited to these examples.
In the examples,% used is based on mass.
The following abbreviations mean the following compounds.
AEDPA; 1-acryloxyethane-1,1-diphosphonic acid; formula 3-1.
MAEDPA; 1-methacryloxyethane-1,1-diphosphonic acid; formula 3-2
GLA; glycerol acrylate; formula 4-1
GLM; Glycerol methacrylate; (Blemmer GLM: NOF Corporation); Formula 4-2
AIBN; Azobisisobutyronitrile

(Measurement of copolymer viscosity)
The viscosity of the synthesized copolymer was measured using a rotational viscometer (RE500L viscometer / cone plate type, manufactured by Toki Sangyo Co., Ltd.). Specific operations are shown below. At a temperature of 25 ° C., 1.1 mL of a 10% by mass aqueous solution of the copolymer was sampled and placed in a viscometer sample cup. After attaching the sample cup to the viscometer body and allowing it to stand for 1 minute, the rotation speed was adjusted according to the sample and the rotor of the viscometer was rotated to read the value after 1 minute.

<Synthesis example of copolymer>
(Preparation of copolymer 1)
MAEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 1. The viscosity of the aqueous solution of the obtained copolymer 1 was 10.7 mPa · s.

(Preparation of copolymer 2)
MAEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. The viscosity of the polymer solution removed by the evaporator is diluted with water and adjusted to a concentration of approximately 10% by weight. The solution is neutralized with sodium hydroxide so that the neutralization rate is 50%, and purified by dialysis membrane for 3 days. Then, an aqueous solution of the copolymer 2 was prepared by adjusting the concentration accurately to 10% by mass after purification. The viscosity of the aqueous solution of the obtained copolymer 2 was 5.1 mPa · s.

(Preparation of copolymer 3)
MAEDPA; 9.0 g, GLA; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 3. The viscosity of the aqueous solution of the obtained copolymer 3 was 11.3 mPa · s.

(Preparation of copolymer 4)
MAEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. The viscous solution obtained by removing the solvent of the polymerization solution with an evaporator is diluted with water and adjusted to a concentration of about 10% by mass, neutralized with potassium hydroxide, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 4. The viscosity of the aqueous solution of the obtained copolymer 4 was 10.8 mPa · s.

(Preparation of copolymer 5)
MAEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. The viscous solution obtained by removing the solvent of the polymerization solution with an evaporator is diluted with water and adjusted to a concentration of about 10% by mass, neutralized with lithium hydroxide, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 5. The viscosity of the aqueous solution of the obtained copolymer 5 was 10.9 mPa · s.

(Preparation of copolymer 6)
MAEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. A viscous solution obtained by removing the solvent from the polymerization solution with an evaporator is diluted with water and adjusted to a concentration of about 10% by mass, neutralized with monoethanolamine (EA), purified by dialysis membrane for 3 days, and after purification, 10% by mass. An aqueous solution of copolymer 6 was prepared by accurately adjusting the concentration. The viscosity of the aqueous solution of the obtained copolymer 6 was 10.3 mPa · s.

(Preparation of copolymer 7)
MAEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. A viscous product obtained by removing the solvent of the polymerization solution with an evaporator is diluted with water and adjusted to a concentration of about 10% by mass, neutralized with dimethylethanolamine (DMEA), purified by dialysis membrane for 3 days, and after purification, 10% by mass. An aqueous solution of the copolymer 7 was prepared by accurately adjusting the concentration. The viscosity of the aqueous solution of the obtained copolymer 7 was 10.6 mPa · s.

(Preparation of copolymer 8)
AEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 8. The viscosity of the aqueous solution of the obtained copolymer 8 was 9.6 mPa · s.

(Preparation of copolymer 9)
MAEDPA; 9.0 g, GLM; 21.0 g, ethanol; 170.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. The viscosity of the polymer solution removed by the evaporator is diluted with water and adjusted to a concentration of approximately 10% by weight. The solution is neutralized with sodium hydroxide to a neutralization rate of 40% and purified by dialysis membrane for 3 days. Then, an aqueous solution of the copolymer 9 was prepared by adjusting the concentration accurately to 10% by mass after purification. The viscosity of the aqueous solution of the obtained copolymer 9 was 2.4 mPa · s.

(Preparation of copolymer 10)
MAEDPA; 4.0 g, GLM; 16.0 g, ethanol; 380.0 g were placed in a four-necked flask and stirred to obtain a homogeneous solution. After nitrogen was blown into this solution for 30 minutes, AIBN (4.0 g) was added at 65 ° C. to carry out a polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 10. The viscosity of the aqueous solution of the obtained copolymer 10 was 1.5 mPa · s.

(Preparation of copolymer 11)
MAEDPA; 4.6 g, GLM; 41.4, ethanol; 154.0 g were placed in a four-necked flask and stirred to obtain a homogeneous solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 11. The viscosity of the aqueous solution of the obtained copolymer 11 was 30.0 mPa · s.

(Preparation of copolymer 12)
MAEDPA; 9.0 g, GLM; 6.0 g, ethanol; 285.0 g were placed in a four-necked flask and stirred to obtain a homogeneous solution. After nitrogen was blown into this solution for 30 minutes, AIBN (3.0 g) was added at 65 ° C. to carry out a polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 12. The viscosity of the aqueous solution of the obtained copolymer 12 was 1.5 mPa · s.

(Preparation of copolymer 13)
MAEDPA; 27.6 g, GLM; 18.4 g, ethanol; 154.0 g were placed in a four-necked flask and stirred to obtain a homogeneous solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 13. The viscosity of the aqueous solution of the obtained copolymer 13 was 30.0 mPa · s.

(Preparation of copolymer 14)
MAEDPA; 6.4 g, GLM; 25.6 g, ethanol; 768.0 g were placed in a four-necked flask and stirred to obtain a homogeneous solution. After nitrogen was blown into this solution for 30 minutes, AIBN (8.0 g) was added at 65 ° C. to carry out a polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 14. The viscosity of the aqueous solution of the obtained copolymer 14 was 1.3 mPa · s.

(Preparation of copolymer 15)
MAEDPA; 5.0 g, GLM; 45.0 g, ethanol; 150.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 15. The viscosity of the aqueous solution of the obtained copolymer 15 was 30.8 mPa · s.

(Preparation of copolymer 16)
MAEDPA; 7.2 g, GLM; 4.8 g, ethanol; 288.0 g were placed in a four-necked flask and stirred to obtain a homogeneous solution. After nitrogen was blown into this solution for 30 minutes, AIBN (3.0 g) was added at 65 ° C. to carry out a polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 16. The viscosity of the aqueous solution of the obtained copolymer 16 was 1.4 mPa · s.

(Preparation of copolymer 17)
MAEDPA; 30.0 g, GLM; 20.0 g, ethanol; 150.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 17. The viscosity of the aqueous solution of the obtained copolymer 17 was 33.9 mPa · s.

(Preparation of copolymer 18)
MAEDPA; 1.6 g, GLM; 30.4 g, ethanol; 768.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. After nitrogen was blown into this solution for 30 minutes, AIBN (8.0 g) was added at 65 ° C. to carry out a polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 18. The viscosity of the aqueous solution of the obtained copolymer 18 was 1.3 mPa · s.

(Preparation of copolymer 19)
MAEDPA; 2.5 g, GLM; 47.5 g, ethanol; 150.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 19. The viscosity of the aqueous solution of the obtained copolymer 19 was 33.6 mPa · s.

(Preparation of copolymer 20)
MAEDPA; 9.6 g, GLM; 2.4 g, ethanol; 288.0 g were placed in a four-necked flask and stirred to obtain a homogeneous solution. After nitrogen was blown into this solution for 30 minutes, AIBN (3.0 g) was added at 65 ° C. to carry out a polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 20. The viscosity of the aqueous solution of the obtained copolymer 20 was 1.2 mPa · s.

(Preparation of copolymer 21)
MAEDPA; 40.0 g, GLM; 10.0 g, ethanol; 150.0 g were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2.0 g was added at 65 ° C. to carry out the polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of copolymer 21. The viscosity of the aqueous solution of the obtained copolymer 21 was 34.8 mPa · s.
Table 1 shows copolymers of synthesis examples.

<Preparation of pigment dispersion>
(Preparation Example 1)
-Preparation of pigment dispersion 1-
After premixing the following carbon black pigment, copolymer and pure water mixture according to the following prescription (1), a disk type bead mill (Shinmaru Enterprises KDL type, media: using zirconia balls having a diameter of 0.1 mm) ) Was circulated and dispersed at a peripheral speed of 10 m / s for 10 minutes to obtain a black pigment dispersion.
Formula (1)
Carbon black pigment NIPEX150 16 parts by mass (Degussa company: gas black)
-Copolymer 1 aqueous solution (solid content 10.0% by mass) 40 parts by mass-Pure water 44 parts by mass

(Preparation Example 2)
-Preparation of pigment dispersion 2-
A pigment dispersion 2 was obtained in the same manner as in Preparation Example 1 except that the formulation of Preparation Example 1 was changed to Formula (2).
Formula (2)
Carbon black pigment NIPEX150 16 parts by mass (Degussa company: gas black)
-20 parts by mass of aqueous solution of copolymer 1 (solid content 10.0% by mass)-64 parts by mass of pure water

(Preparation Example 3)
-Preparation of pigment dispersion 3-
A pigment dispersion 3 was obtained in the same manner as in Preparation Example 1 except that the formulation of Preparation Example 1 was changed to Formula (3).
Formula (3)
Carbon black pigment NIPEX150 16 parts by mass (Degussa company: gas black)
-Copolymer 1 aqueous solution (solid content 10.0% by mass) 80 parts by mass-Pure water 4 parts by mass

(Preparation Example 4)
-Preparation of pigment dispersion 4-
A pigment dispersion 4 was obtained in the same manner as in Preparation Example 1 except that the formulation of Preparation Example 1 was changed to Formula (4).
Formula (4)
Carbon black pigment NIPEX150 16 parts by mass (Degussa company: gas black)
-80 parts by mass of an aqueous solution in which the aqueous solution of copolymer 1 has a solid content of 20.0% by mass-4 parts by mass of pure water

(Preparation Example 5)
-Preparation of pigment dispersion 5-
A pigment dispersion 5 was obtained in the same manner as in Preparation Example 1 except that the carbon black pigment of Preparation Example 1 was changed to Pigment Blue 15: 3.

(Preparation Example 6)
-Preparation of pigment dispersion 6-
A pigment dispersion 6 was obtained in the same manner as in Preparation Example 1 except that the carbon black pigment of Preparation Example 1 was changed to Pigment Red 122.

(Preparation Example 7)
-Preparation of pigment dispersion 7-
A pigment dispersion 7 was obtained in the same manner as in Preparation Example 1 except that the carbon black pigment of Preparation Example 1 was changed to Pigment Yellow 74.

(Preparation Examples 8 to 13)
-Preparation of pigment dispersions 8-13-
Pigment dispersions 8 to 13 were obtained in the same manner as in Preparation Example 1 except that the aqueous solution of the copolymer 1 of Preparation Example 1 was changed to the aqueous solution of Copolymers 2 to 7.

(Preparation Example 14)
-Preparation of pigment dispersion 14-
A pigment dispersion 14 was obtained in the same manner as in Preparation Example 1 except that the aqueous solution of the copolymer 1 of Preparation Example 1 was changed to the aqueous solution of the copolymer 8.

(Preparation Example 15)
-Preparation of pigment dispersion 15-
A pigment dispersion 15 was obtained in the same manner as in Preparation Example 14 except that the carbon black pigment of Preparation Example 14 was changed to Pigment Blue 15: 3.

(Preparation Example 16)
-Preparation of pigment dispersion 16-
A pigment dispersion 16 was obtained in the same manner as in Preparation Example 14 except that the carbon black pigment of Preparation Example 14 was changed to Pigment Red 122.

(Preparation Example 17)
-Preparation of pigment dispersion 17-
A pigment dispersion 17 was obtained in the same manner as in Preparation Example 14 except that the carbon black pigment of Preparation Example 14 was changed to Pigment Yellow 74.

(Preparation Examples 18-30)
-Preparation of pigment dispersions 18-30-
Pigment dispersions 18 to 30 were obtained in the same manner as in Preparation Example 1 except that the aqueous solution of the copolymer 1 of Preparation Example 1 was changed to the aqueous solution of the copolymers 9 to 21.

<Synthesis example of comparative copolymer>
(Preparation of comparative copolymer 1)
500 g of water and 15 g of animmonium persulfate, 100 g of maleic acid, 100 g of styrene, 500 g of water and 15 g of animmonium persulfate were placed in a four-necked flask and stirred to obtain a uniform solution. Nitrogen was blown into this solution for 30 minutes, and then AIBN; 2 g was added at 80 to 90 ° C. to cause a polymerization reaction for 5 hours or more. Neutralized with sodium hydroxide, adjusted to a concentration of approximately 10% by mass while diluting the viscous product obtained by removing the solvent of the polymerization solution with an evaporator in water, purified by dialysis membrane for 3 days, and accurately purified to 10% by mass. The solution whose concentration was adjusted was used as an aqueous solution of comparative copolymer 1. The viscosity of the aqueous solution of the obtained comparative copolymer 1 was 13.5 mPa · s.

(Preparation of comparative copolymer 2)
An aqueous solution of Comparative Copolymer 2 was obtained in the same manner as Comparative Copolymer 1 except that MAEDPA and styrene were used instead of maleic acid and styrene in the production of Comparative Copolymer 1. The viscosity of the aqueous solution of the obtained comparative copolymer 2 was 14.4 mPa · s.

(Preparation of comparative copolymer 3)
An aqueous solution of Comparative Copolymer 3 was obtained in the same manner as Comparative Copolymer 1 except that maleic acid and styrene were changed to maleic acid and GLM in the production of Comparative Copolymer 1. The viscosity of the aqueous solution of the obtained comparative copolymer 3 was 14.1 mPa · s.

Table 2 shows copolymers of comparative synthesis examples.

<Preparation of pigment dispersion>
(Comparative Preparation Example 1)
-Preparation of Comparative Pigment Dispersion 1-
Comparative pigment dispersion 1 was obtained in the same manner as in Preparation Example 1, except that the aqueous solution of copolymer 1 of Preparation Example 1 was changed to an aqueous solution of Comparative Copolymer 1.

(Comparative Preparation Example 2)
-Preparation of Comparative Pigment Dispersion 2-
A comparative pigment dispersion 2 was obtained in the same manner as in Comparative Preparation Example 1 except that the carbon black pigment of Comparative Preparation Example 1 was changed to Pigment Blue 15: 3.

(Comparative Preparation Example 3)
-Preparation of Comparative Pigment Dispersion 3-
A comparative pigment dispersion 3 was obtained in the same manner as in Comparative Preparation Example 1 except that the carbon black pigment of Comparative Preparation Example 1 was changed to Pigment Red 122.

(Comparative Preparation Example 4)
-Preparation of Comparative Pigment Dispersion 4-
Comparative pigment dispersion 4 was obtained in the same manner as in Comparative Preparation Example 1 except that the carbon black pigment of Comparative Preparation Example 1 was changed to Pigment Yellow 74.

(Comparative Preparation Example 5)
-Preparation of Comparative Pigment Dispersion 5-
Comparative pigment dispersion 5 was obtained in the same manner as Comparative Preparation Example 1 except that the aqueous solution of Comparative Copolymer 1 of Comparative Preparation Example 1 was changed to the aqueous solution of Comparative Copolymer 2.

(Comparative Preparation Example 6)
-Preparation of Comparative Pigment Dispersion 5-
Comparative pigment dispersion 6 was obtained in the same manner as in Comparative Preparation Example 1 except that the aqueous solution of Comparative Copolymer 1 of Comparative Preparation Example 1 was changed to the aqueous solution of Comparative Copolymer 3.

[Examples 1-42 and Comparative Examples 1-6]
<Inkjet ink manufacturing method>
(Example 1)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 1 of Preparation Example 1 (pigment concentration 16% by mass) 50.0 parts by mass-1,3-butanediol 15.0 parts by mass-Glycerin 20.0 parts by mass-2-Ethyl-1,3-hexane Diol 1.0 part by mass 2,2,4-trimethyl-1,3-pentanediol 1.0 part by mass FS-300: polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40 mass% component) 2.5 parts by mass / pure water 10.5 parts by mass

(Examples 2 to 4)
Inks of Examples 2 to 4 were obtained in the same manner as in Example 1, except that the pigment dispersion 1 was changed to the pigment dispersions 2 to 4.

(Example 5)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 1 of Preparation Example 1 (pigment concentration 16% by mass) 50.0 parts by mass-1,3-butanediol 15.0 parts by mass-Glycerin 20.0 parts by mass-2-Ethyl-1,3-hexane Diol 1.0 part by mass 2,2,4-trimethyl-1,3-pentanediol 1.0 part by mass FS-300: polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40% by mass of ingredients) 2.5 parts by mass. Acrylic-silicone resin emulsion:
(Polysol ROY6312 manufactured by Showa Polymer Co., Ltd.) 6.0 parts by mass / pure water 4.5 parts by mass

(Example 6)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 5 of Preparation Example 5 (pigment concentration: 16% by mass) 40.0 parts by mass-1,3-butanediol 15.0 parts by mass-Glycerin 20.0 parts by mass-2-Ethyl-1,3-hexane Diol 2.0 parts by mass Fluorosurfactant (KF-643) 1.0 part by mass FS-300: Polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40 mass% component) 2.5 parts by mass / pure water 19.5 parts by mass

(Example 7)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 6 of Preparation Example 6 (pigment concentration: 16% by mass) 40.0 parts by mass-1,3-butanediol 15.0 parts by mass-Glycerin 20.0 parts by mass-2-Ethyl-1,3-hexane Diol 2.0 parts by mass Fluorosurfactant (KF-643) 1.0 part by mass FS-300: Polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40 mass% component) 2.5 parts by mass / pure water 19.5 parts by mass

(Example 8)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 7 of Preparation Example 7 (pigment concentration: 16% by mass) 40.0 parts by mass-1,3-butanediol 15.0 parts by mass-Glycerin 20.0 parts by mass-2-Ethyl-1,3-hexane Diol 2.0 parts by mass Fluorosurfactant (KF-643) 1.0 part by mass FS-300: Polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40 mass% component) 2.5 parts by mass / pure water 19.5 parts by mass

(Examples 9 to 15)
Inks of Examples 9 to 15 were obtained in the same manner as in Example 1, except that the pigment dispersion 1 was changed to the pigment dispersions 8 to 14.

(Examples 16 to 19)
Inks of Examples 16 to 19 were obtained in the same manner as in Examples 5 to 8, except that the pigment dispersions 1 and 5 to 7 were changed to the pigment dispersions 14 to 17.

(Examples 20 to 32)
Inks of Examples 20 to 32 were obtained in the same manner as in Example 1, except that the pigment dispersion 1 was changed to the pigment dispersions 18 to 30.

(Example 33)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 1 of Preparation Example 1 (pigment concentration 16% by mass) 50.0 parts by mass-1,3-butanediol 35.0 parts by mass-2-ethyl-1,3-hexanediol 1.0 part by mass- 2,2,4-Trimethyl-1,3-pentanediol 1.0 part by mass FS-300: polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40 mass% component) 2.5 parts by mass / pure water 10.5 parts by mass

(Example 34)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 13 of Preparation Example 13 (pigment concentration 16% by mass) 50.0 parts by mass-1,3-butanediol 35.0 parts by mass-2-ethyl-1,3-hexanediol 1.0 part by mass- 2,2,4-Trimethyl-1,3-pentanediol 1.0 part by mass FS-300: polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40 mass% component) 2.5 parts by mass / pure water 10.5 parts by mass

(Example 35)
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.
-Pigment dispersion 14 of Preparation Example 14 (pigment concentration 16% by mass) 50.0 parts by mass-1,3-butanediol 35.0 parts by mass-2-ethyl-1,3-hexanediol 1.0 part by mass- 2,2,4-Trimethyl-1,3-pentanediol 1.0 part by mass FS-300: polyoxyethylene perfluoroalkyl ether
(Manufactured by Dupont, 40 mass% component) 2.5 parts by mass / pure water 10.5 parts by mass

(Example 36)
-Preparation of ink for ink jet recording by addition of copolymer-
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink for inkjet recording.
-Comparative pigment dispersion 1 of Comparative Preparation Example 1 (pigment concentration 16% by mass) 50.0 parts by mass-Copolymer 1 0.5 parts by mass-1,3-butanediol 15.0 parts by mass-Glycerin 20.0 Parts by mass, 2-ethyl-1,3-hexanediol 1.0 parts by mass, 2,2,4-trimethyl-1,3-pentanediol 1.0 parts by mass, polyoxyethylene perfluoroalkyl ether
(FS-300, manufactured by Dupont, 40% by mass of ingredients) 2.5 parts by mass / pure water 10.0 parts by mass

(Example 37)
-Preparation of ink for ink jet recording by addition of copolymer-
Example 36 except that the amount of copolymer 1 of Example 36 was changed from 0.5 parts by mass to 2.0 parts by mass, and the amount of pure water was changed from 10.0 parts by mass to 8.5 parts by mass. In the same manner as described above, an ink for inkjet recording of Example 37 was obtained.

(Example 38)
-Preparation of ink for ink jet recording by addition of copolymer-
Example 36, except that the amount of copolymer 1 of Example 36 was changed from 0.5 parts by mass to 5.0 parts by mass, and the amount of pure water was changed from 10.0 parts by mass to 5.5 parts by mass. In the same manner as described above, an inkjet recording ink of Example 38 was obtained.

(Example 39)
-Preparation of ink for ink jet recording by addition of copolymer-
Example 36 Except that the amount of the copolymer 1 of Example 36 was changed from 0.5 parts by mass to 10.0 parts by mass, and the amount of pure water was changed from 10.0 parts by mass to 0.5 parts by mass. In the same manner as described above, an inkjet recording ink of Example 39 was obtained.

(Example 40)
-Preparation of ink by addition of copolymer-
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink for inkjet recording.
-Pigment dispersion Comparative pigment dispersion 2 of Comparative Preparation Example 2 (pigment concentration: 16% by mass)
40.0 parts by mass Copolymer 1 2.0 parts by mass 1,3-butanediol 15.0 parts by mass Glycerin 20.0 parts by mass 2-ethyl-1,3-hexanediol 2.0 parts by mass・ Polyoxyethylene perfluoroalkyl ether
(FS-300, manufactured by Dupont, 40% by mass of ingredients) 2.5 parts by mass / pure water 17.5 parts by mass

(Example 41)
-Preparation of ink by addition of copolymer-
An ink jet recording ink of Example 41 was obtained in the same manner as in Example 40 except that the pigment dispersion of Example 40 was changed from the comparative pigment dispersion 2 to the comparative pigment dispersion 3.

(Example 42)
-Preparation of ink by addition of copolymer-
An ink jet recording ink of Example 42 was obtained in the same manner as in Example 40 except that the pigment dispersion of Example 40 was changed from the comparative pigment dispersion 2 to the comparative pigment dispersion 4.

(Comparative Example 1)
An ink of Comparative Example 1 was obtained in the same manner as in Example 1, except that the pigment dispersion 1 was changed to the comparative pigment dispersion 1.

(Comparative Example 2)
An ink of Comparative Example 2 was obtained in the same manner as in Example 6, except that the pigment dispersion 5 was changed to the comparative pigment dispersion 2.

(Comparative Example 3)
An ink of Comparative Example 3 was obtained in the same manner as in Example 7, except that the pigment dispersion 6 was changed to the comparative pigment dispersion 3.

(Comparative Example 4)
The ink of Comparative Example 4 was obtained in the same manner as in Example 8, except that the pigment dispersion 7 was changed to the comparative pigment dispersion 4.

(Comparative Example 5)
An ink of Comparative Example 5 was obtained in the same manner as in Example 1, except that the pigment dispersion 1 was changed to the comparative pigment dispersion 5.

(Comparative Example 6)
An ink of Comparative Example 6 was obtained in the same manner as in Example 1, except that the pigment dispersion 1 was changed to the comparative pigment dispersion 6.

Tables 3, 4 and 5 show examples used as dispersants, Table 6 shows examples used as additives, and Table 7 shows comparative examples.

  Next, each ink-jet ink of Examples 1-42 and Comparative Examples 1-6 was evaluated by the following evaluation method. The results are shown in Table 8 below.

<Image density>
In a 23 ° C. and 50% RH environment, an ink jet printer (IPSiO GX5000 manufactured by Ricoh) was filled with the ink prepared, and the general symbol of JIS X 0208 (1997), 2223 of 64 points manufactured by Microsoft Word 2000 (manufactured by Microsoft) was The described chart was printed on MyPaper (manufactured by Ricoh Co., Ltd.), and the symbol part on the printed surface was measured with X-Rite 938, and judged according to the following evaluation criteria.
Note that JIS X 0208 (1997), 2223 is a symbol whose outer shape is a regular square and the entire symbol surface is filled with ink.
The printing mode used was a driver attached to the printer, in which the "plain paper-standard fast" mode was changed to "no color correction" from the user setting for plain paper.

〔Evaluation criteria〕
AA: Black: 1.25 or more
Magenta: 1.00 or more
Cyan: 1.00 or more
Yellow: 0.85 or more A: Black: 1.20 or more and less than 1.25
Magenta: 0.95 or more and less than 1.00
Cyan: 0.95 or more and less than 1.00
Yellow: 0.80 or more and less than 0.85 B: Black: 1.15 or more and less than 1.20
Magenta: 0.90 or more and less than 0.95
Cyan: 0.90 or more and less than 0.95
Yellow: 0.75 or more and less than 0.80 C: Black: 1.10 or more and less than 1.15
Magenta: 0.85 or more and less than 0.90
Cyan: 0.85 or more and less than 0.90
Yellow: 0.70 or more and less than 0.75 D: Black: less than 1.10
Magenta: Less than 0.85
Cyan: Less than 0.85
Yellow: less than 0.70

<Ink storage stability>
Each ink was filled in an ink cartridge and stored at 60 ° C. for 2 weeks, and the change in viscosity after storage with respect to the viscosity before storage was evaluated according to the following criteria.
The viscosity was measured using a rotational viscometer (RE500L viscometer / cone plate type, manufactured by Toki Sangyo Co., Ltd.). Specific operations are shown below. At a temperature of 25 ° C., 1.1 mL of ink is taken and placed in a viscometer sample cup. After attaching the sample cup to the viscometer body and allowing to stand for 1 minute, the rotor of the viscometer is rotated and the value after 1 minute is read. Note that the number of rotations of the rotor is adjusted according to the sample.
[Evaluation criteria]
A: Change in viscosity is less than ± 3% A: Change in viscosity is ± 3% or more and less than ± 6% B: Change in viscosity is ± 6% or more and less than ± 10% C: Change in viscosity is ± 10% or more and ± 20 Less than% D: Change in viscosity is 20% or more

<Ink ejection stability>
Regarding ejection stability, after printing a printed matter, the printer was left in a 50 ° C. environment for one month with the printer head capped. Whether or not the discharge state of the printer after being left is restored to the initial discharge state was evaluated according to the following evaluation criteria by the following number of cleaning operations.
[Evaluation criteria]
AA: Printing was possible without cleaning.
A: Recovered by 1 to 3 operations.
B: Recovered by 4-5 operations.
C: Recovered by 6 to 10 operations.
D: No recovery was observed even after 10 or more operations.

From the evaluation results, the ink of the present invention containing at least the structural unit represented by the general formula (1) and the copolymer of the structural unit represented by the general formula (2) as the ink composition, Also, the image density, ink storage stability, and ink ejection stability are excellent, and characteristics that are problematic in practical use are not observed.
Comparison between Examples 1-42 and Comparative Examples 1-6 reveals that the ink of the present invention has a high image density and excellent storage stability and ejection stability.
Further, the following can be understood from the comparison between the examples.
From the comparison between Examples 1 and 9 and 20, the effect is obtained even if the neutralization rate of the general formula (1) is different, and the higher neutralization rate is superior in terms of storage stability or ejection stability.
From the comparison between Examples 1 and 5 to 8 and 15 to 19, the same effect can be obtained regardless of whether R1 in the general formula (1) is a methyl group or hydrogen.
From comparison between Examples 1 and 10, it is excellent in terms of storage stability that R3 in the general formula (2) is a methyl group.
An effect is acquired from Example 1, 11-14 irrespective of the kind of neutralization salt of General formula (1), and an organic amine is excellent in the point of discharge stability.
From the comparison between Examples 1 to 24 and 25 to 28, the ratio of the general formula (1) is 10 to 60% by mass, and the viscosity of the 10% by mass aqueous solution of the copolymer containing phosphonic acid groups is 1.5 to At 30.0 mPa · s, the image density, storage stability, and ejection stability are excellent.
From a comparison between Examples 25-28 and 29-32, the ratio of the general formula (1) is 10 to 60% by mass, which is excellent in terms of image density.
From the comparison of Examples 1, 6 to 8, and 15, 17 to 19, the same effect can be obtained regardless of the color of the pigment.
From Examples 1 and 5, 15 and 16, the same effect can be obtained regardless of the ink formulation.
From the comparison between Examples 1, 14, 15 and 33, 34, 35, it is understood that the discharge stability is excellent when glycerin is contained.

In the ink of the present invention, it can be seen that the image density is clearly excellent in each color ink and the ink storage stability is excellent due to the aggregation effect due to the reaction with calcium ions.
That is, the present invention has good ink storage stability and good drying properties, and a high image density can be obtained with plain paper or coated paper for printing, and can be applied to various recordings by an ink jet recording method. . The ink recorded matter of the present invention has high image quality, no bleeding, excellent stability over time, and can be suitably used for various purposes as materials on which various prints or images are recorded. As the recording apparatus using the ink jet recording method, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like can be applied.

101 apparatus main body 102 paper feed tray 103 paper discharge tray 104 ink cartridge loading unit 105 operation unit 111 upper cover 112 front surface 115 front cover 131 guide rod 132 stay 133 carriage 134 recording head 135 sub tank 141 paper placement unit 142 paper 143 paper supply roller 144 Separator Pad 145 Guide 151 Conveyor Belt 152 Counter Roller 153 Conveyor Guide 154 Pressing Member 155 Tip Pressing Roller 156 Charging Roller 157 Conveying Roller 158 Tension Roller 161 Guide Member 171 Separating Claw 172 Paper Discharge Roller 173 Paper Discharge Roller 181 Double-sided Paper Feed Unit 182 Manual paper feed unit 200 Ink cartridge 241 Ink bag 242 Ink inlet 243 Ink outlet 244 Cartridge case

JP 2011-122072 A

Claims (12)

An inkjet recording ink containing at least water, a water-soluble solvent, a pigment, and a copolymer containing a phosphonic acid group,
The inkjet recording ink, wherein the copolymer containing a phosphonic acid group has at least a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2): .

[R1 in Formula (1) represents a hydrogen atom or a methyl group. R2 represents an alkyl group having 1 to 4 carbon atoms. M ⁺ represents a proton, an alkali metal ion or an organic ammonium ion. ]

[R3 in Formula (2) represents a hydrogen atom or a methyl group. ]   The ink for inkjet recording according to claim 1, wherein the content of the structural unit represented by the general formula (1) in the copolymer containing the phosphonic acid group is 10% by mass to 60% by mass.   The ink for inkjet recording according to claim 1 or 2, wherein the viscosity of the aqueous solution containing 10% by mass of the phosphonic acid group-containing copolymer is 1.5 to 30.0 mPa · s.   The ink for inkjet recording according to any one of claims 1 to 3, wherein R3 of the structural unit represented by the general formula (2) of the copolymer containing the phosphonic acid group is a methyl group. The ink for inkjet recording according to any one of claims 1 to 4, wherein M ^{+ of the} structural unit represented by the general formula (1) of the copolymer containing the phosphonic acid group is an organic ammonium ion. . An inkjet recording ink containing at least water, a water-soluble solvent, a pigment, and a copolymer containing a phosphonic acid group,
The inkjet recording characterized in that the copolymer containing a phosphonic acid group is synthesized using at least a monomer represented by the following general formula (3) and a monomer represented by the following general formula (4) as starting materials. For ink.

[R4 in Formula (3) represents a hydrogen atom or a methyl group. R5 represents an alkyl group having 1 to 4 carbon atoms. ]

[R6 in Formula (4) represents a hydrogen atom or a methyl group. ]   The ink for inkjet recording according to any one of claims 1 to 6, wherein the water-soluble solvent contains at least glycerin.   The ink for inkjet recording according to any one of claims 1 to 7, wherein a copolymer containing the phosphonic acid group is used as a dispersant.   An ink cartridge comprising the ink-jet recording ink according to claim 1 contained in a container.   It includes at least an ink flying step of recording an image on a recording medium by applying a stimulus to the ink for ink jet recording according to any one of claims 1 to 8 via an ink flying means and flying the ink from a recording head. A method for producing an ink jet recorded product.   An ink jet recording apparatus comprising ink jetting means for jetting the ink for ink jet recording according to claim 1 from a recording head to record an image on a recording medium.   An ink recorded matter comprising an image recorded with the ink for ink jet recording according to claim 1 on a recording medium.

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