JP2015081273A - Ink for inkjet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink for inkjet recording which gives high image density and has excellent storage stability.SOLUTION: The ink for inkjet recording comprises at least water, a water-soluble solvent, a pigment, and a copolymer containing a salt of a diphosphonic acid group; and the copolymer contains a structural unit expressed by general formula (1) and a structural unit of N-(1,1 dimethyl-2-acetylethyl)-(meth)acrylamide. In general formula (1), Rrepresents H or a methyl group; X represents an alkylene group having 1 to 3 carbon atoms; and M+ represents an alkali metal ion or an organic ammonium ion, or a proton, where an alkali metal and a proton, and an organic ammonium ion and a proton may be present together, and half or more of M+ in the copolymer is an alkali metal ion or an organic ammonium ion.

Description

  The present invention relates to an ink for ink jet recording (hereinafter sometimes simply referred to as “ink”), an ink cartridge, an ink jet recording method, a recording apparatus, and a recorded matter.

  The inkjet recording method is popular because it has the advantage that the process is simpler than other recording methods, full color is easy, and even high-resolution images can be obtained even with a simple configuration. Have been doing. In this ink jet recording system, a small amount of ink is ejected by pressure generated using bubbles generated by heat, piezo or static electricity, and is adhered to a recording medium such as paper and dried quickly (or recording). This is a method of forming an image by penetrating into a medium), and its application has been expanded to personal and industrial printers and printing.

In such an ink jet recording system, a water-based ink using a water-soluble dye as a colorant is mainly used. However, the dye ink has a defect that it is inferior in weather resistance and water resistance. For this reason, research on pigment inks that use water-insoluble pigments instead of water-soluble dyes is underway. 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 of OA printers, high image density is required even when plain paper is used as a recording medium in pigment ink. However, when the plain ink is used as the recording medium, the pigment ink has a problem that the pigment density on the paper surface is lowered by permeating into the paper and the image density is lowered.

  In recent years, the demand for industrial applications has increased, and high-speed printing is desired. An ink jet printer equipped with a line head has been proposed along with such high-speed printing. In order to achieve high-speed printing, in order to increase the drying speed of the ink adhering to the recording medium, means for increasing the drying speed by adding a penetrant to the ink and allowing water to penetrate into the recording medium has been tried. In addition to this, there is a problem that the permeability of the pigment into the recording medium is increased and the image density is lowered.

In addition, when plain paper is used as a recording medium, there is a problem that immediately after printing, the surface of the plain paper is swollen by water as an ink solvent, the difference in elongation between the front and back is increased, and curling occurs. Since such a phenomenon disappears as the drying progresses, there was no problem in low-speed printing.
However, with the increase in printing speed, it is necessary to transport the recording medium without eliminating curling after printing, which may cause a paper jam problem. As for curling, a means for increasing the content of the organic solvent in the ink is effective, but since the ink is more hydrophobic, it is difficult to ensure the storage stability of the ink.

In order to solve the above problems, for example, an ink-jet ink composition containing a liquid vehicle, a colorant, and a polymer having at least one functional group having a specific calcium index value has been proposed (see Patent Document 1). In this proposal, 4-methacrylamide-1-hydroxybutane-1,1-diphosphonic acid is shown as a monomer constituting the polymer, and when the colorant comes into contact with the paper, the diphosphonic acid group of the polymer and the paper It is said that the printed image can be improved by making it unstable with the Ca salt therein.
However, in the proposed technique, the polymer is not used as a dispersant and an additive for a pigment dispersion, but the polymer is coated with a colorant, and the diphosphonic acid group is an alkali metal salt or an organic ammonium salt. Not salt.

  In addition, an ink jet recording method has been proposed in which a receiving liquid containing a Ca salt is attached to paper, and an ink containing a pigment having a phosphorus-containing group bonded thereto, a resin emulsion, and a surfactant is printed (see Patent Document 2). This proposal describes that bisphosphonic acid is preferable as the phosphorus-containing group, and describes that the Ca salt of the receiving solution reacts with the phosphorus-containing group and has an effect of improving feathering and fixing properties. Yes. However, in the proposed technique, a phosphonic acid group-containing polymer is not used as a dispersant and an additive for a pigment dispersion, but a pigment bonded with phosphoric acid is used, and an image when recorded on plain paper is used. The effect of increasing the concentration is not sufficient.

  Further, an aqueous ink containing a colorant, water, a water-soluble organic solvent, a surfactant, and a chelating agent has been proposed (see Patent Document 3). In this proposal, hydroxyethylidene diphosphonic acid or a salt thereof, which is a low molecular compound, is used as the chelating agent. The chelating agent is said to be able to remove calcium and the like contained in a dispersion such as a pigment and improve discharge stability and storage stability. However, the proposal only describes a low molecular weight compound, hydroxyethylidene diphosphonic acid, and does not describe a polymer containing phosphonic acid, and improves the image density when recorded on a chelating agent and plain paper. It also does not describe the relationship with effects.

  Therefore, it is desired to provide an ink for ink jet recording which can obtain a high image density even when recorded on plain paper and has excellent storage stability even when the content of the water-soluble organic solvent is increased.

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 ink jet recording that provides a high image density and is excellent in storage stability.

  The ink for ink jet recording of the present invention as means for solving the above problems is (1) “an ink for ink jet recording having a copolymer containing at least water, a water-soluble solvent, a pigment, and a salt of a diphosphonic acid group”. The copolymer containing a salt of the diphosphonic acid group has at least a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2). .

(R ₁ in the general formula (1) represents a hydrogen atom or a methyl group, X represents an alkylene group having 1 to 3 carbon atoms, and M + represents an alkali metal ion, an organic ammonium ion, or a proton. Metals and protons and organic ammonium ions and protons may be mixed, and more than half of M + in the copolymer is alkali metal ions or organic ammonium ions.)

（一般式（２）中のＲ_１は、水素原子またはメチル基を表す。）

(R ₁ in the general formula (2) represents a hydrogen atom or a methyl group.)

  According to the present invention, the conventional problems can be solved, the object can be achieved, a high image density can be obtained, and an ink for ink jet recording excellent in storage stability can be provided.

It is the schematic plan view seen from the nozzle surface which shows an example (2 head type) of the recording head arrange | positioned at the inkjet recording device of this invention. It is the schematic plan view seen from the nozzle surface which shows another example (4 head type) of the recording head arrange | positioned at the inkjet recording device of this invention. FIG. 3 is a perspective explanatory view seen from the front side showing an example of an ink jet recording apparatus of the present invention having a maintenance / recovery device. It is a schematic block diagram explaining the whole structure of the mechanism part of the inkjet recording device shown in FIG. It is principal part plane explanatory drawing of the mechanism part of the inkjet recording device shown in FIG. It is principal part top explanatory drawing of the subsystem 91 containing the maintenance recovery apparatus in the inkjet recording device of this invention. It is a typical schematic block diagram of the subsystem shown in FIG. FIG. 8 is an explanatory diagram on the right side of the subsystem shown in FIG. 7. It is side surface explanatory drawing of the holding | maintenance raising / lowering mechanism part of the cap 92. FIG.

The present invention relates to the “ink jet recording ink” described in the above (1). As will be understood from the following detailed and specific description, the “ink jet recording ink” is described below. (2) to (5) include the “ink-jet recording ink” according to the embodiment.
The present invention also includes the “ink cartridge”, “inkjet recording method”, “inkjet recording apparatus”, and “ink recorded matter” described in the following (6) to (9).
(2) The inkjet according to (1), wherein the content of the structural unit of the general formula (1) in the copolymer containing the salt of the diphosphonic acid group is 30% by mass to 70% by mass. Recording ink. "
(3) The inkjet according to (2), wherein the content of the structural unit of the general formula (1) in the copolymer containing a salt of the diphosphonic acid group is 40% by mass to 60% by mass. Recording ink. "
(4) Any of (1) to (3) above, wherein the aqueous solution viscosity (concentration: 10% by mass, 25 ° C.) of the copolymer containing a salt of the diphosphonic acid group is 2 to 4 mPa · s. Ink for inkjet recording according to the above. "
(5) In the inkjet recording ink having a copolymer containing at least water, a water-soluble solvent, a pigment, and a salt of a diphosphonic acid group, the copolymer containing the salt of the diphosphonic acid group is represented by the general formula (3). An ink for ink jet recording, which is synthesized by radical polymerization using at least a monomer represented by the formula and a monomer represented by the general formula (4) as a starting material.

(R ₁ in the general formula (3) represents a hydrogen atom or a methyl group, X represents an alkylene group having 1 to 3 carbon atoms, and M + represents an alkali metal ion, an organic ammonium ion, or a proton.)

（一般式（４）中のＲ_１は、水素原子またはメチル基を表す。）

(R ₁ in the general formula (4) represents a hydrogen atom or a methyl group.)

(6) “An ink cartridge comprising the ink for inkjet recording according to any one of (1) to (5) contained in a container”
(7) “At least an ink flying step of recording an image by applying a stimulus to the ink for ink jet recording according to any one of (1) to (5) and causing the ink for ink jet recording to fly. Inkjet recording method. "
(8) “At least ink ejecting means for recording an image by applying a stimulus to the ink for ink jet recording according to any one of (1) to (5) and causing the ink for ink jet recording to eject. Inkjet recording apparatus. "
(9) “An ink recorded matter comprising an image recorded on the recording medium with the ink for ink jet recording according to any one of (1) to (5)”.

--Copolymer containing salt of phosphonic acid group--
Hereinafter, the present invention will be described in detail.
As described above, the copolymer containing a salt of a phosphonic acid group in the present invention has at least a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2). It is.

(R ₁ in the general formula (1) represents a hydrogen atom or a methyl group, X represents an alkylene group having 1 to 3 carbon atoms, and M + represents an alkali metal ion, an organic ammonium ion, or a proton. Metals and protons and organic ammonium ions and protons may be mixed, and more than half of M + in the copolymer is alkali metal ions or organic ammonium ions.)

（一般式（２）中のＲ_１は、水素原子またはメチル基を表す。）

(R ₁ in the general formula (2) represents a hydrogen atom or a methyl group.)

Examples of the alkylene group having 1 to 3 carbon atoms of X in the general formula (1) include a methylene group, an ethylene group, and a propylene group.
In the present invention, the effect of the propylene group will be described with reference to examples, but the same effect is exhibited when X is a methylene group or an ethylene group.
Examples of the alkali metal in the M ⁺ alkali metal ion in the general formula (1) include lithium, sodium, and potassium.
Examples of the organic amine in the M ⁺ organic ammonium ion include alkylamines such as mono-, di- or trimethylamine, mono-, di- or triethylamine; ethanolamine, diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, dimethylethanol Alcohol amines such as amine, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, trishydroxymethylaminomethane, 2-amino-2-ethyl-1,3propanediol (AEPD); choline, morpholine, N -Cyclic amines such as methylmonoformin, N-methyl-2-pyrrolidone and 2-pyrrolidone.
In particular, sodium ions, potassium ions, and ammonium ions of trialkylamine are desirable from the viewpoint of both image density and storage stability.
As M ⁺ , more than half or all of them are preferably alkali metal ions or organic ammonium ions, and the rest are preferably hydrogen ions (protons).
The mass ratio of the structural unit represented by the general formula (1) is not particularly limited and may be appropriately selected depending on the intended purpose. 40 mass%-60 mass% is still more preferable. When the mass ratio is within the more preferable range, it is advantageous in that when used for an ink jet recording ink, a high image density is obtained, and dispersion stability and storage stability are improved.

  A copolymer containing a salt of a phosphonic acid group can be produced by the method for producing a polymer of the present invention described below. Moreover, the copolymer containing the structural unit represented by the general formula (1) and the general formula (2) is not particularly limited and can be widely used in various fields. Then, it can be suitably used as a pigment dispersant, pigment concentration improver, pigment binder resin, viscosity modifier and the like in ink jet recording ink.

<Method for producing polymer>
In the method for producing a polymer used in the present invention, at least after the compounds represented by the following general formula (3) and general formula (4) are polymerized, the obtained polymer is either an alkali metal base or an organic amine base. It can be synthesized by neutralizing with.

(R ₁ in the general formula (3) represents a hydrogen atom or a methyl group, X represents an alkylene group having 1 to 3 carbon atoms, and M + represents an alkali metal ion, an organic ammonium ion, or a proton.)

（一般式（４）中のＲ_１は、水素原子またはメチル基を表す。）

(R ₁ in the general formula (4) represents a hydrogen atom or a methyl group.)

When X is a propylene group, the monomer represented by the general formula (3) is prepared by neutralizing alendronic acid with an alkali metal base or an organic amine base in the range of 1 to 3 equivalents in advance, and then methacrylic acid. It can be obtained by reacting with chloride or acrylic acid chloride.
When X is a methylene group or an ethylene group, it can be obtained by using a bisphosphonic acid compound obtained by phosphonating aminoacetic acid or 2-aminoethanoic acid with phosphorous acid and phosphorus trichloride instead of alendronic acid. .
As a method for synthesizing the polymer containing the structural units represented by the general formula (1) and the general formula (2), a method using a radical polymerization initiator is preferable because the polymerization operation and the adjustment of the molecular weight are easy. A solution polymerization method in which polymerization is performed in a mixed solvent of an organic solvent and water is more preferable.
The solvent used for radical polymerization by the solution polymerization method is not particularly limited, but the monomer of the general formula (3) is supplied as an aqueous solution, and the monomer of the general formula (4) is dissolved in an organic solvent and supplied. However, it is preferable to carry out the polymerization while the organic solvent is preferably water-soluble.
For example, alcohol solvents such as methanol and ethanol, ether solvents such as tetrahydrofuran, and amide solvents such as N, N-dimethylformamide are preferable.

The radical polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. For example, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester Cyano azobisisobutyronitrile, azobis (2-methylbutyronitrile), azobis (2,2′-isovaleronitrile), non-cyano dimethyl-2,2′-azobisisobutyrate, Etc. Among these, organic peroxides and azo compounds are preferable, and azo compounds are particularly preferable from the viewpoint of easy control of molecular weight and low decomposition temperature.
The content of the polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1% by mass to 20% by mass with respect to the total mass of the polymerizable monomer.

In order to adjust the molecular weight of the polymer, an appropriate amount of a chain transfer agent may be added.
Examples of the chain transfer agent include mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, nonyl mercaptan, 1-dodecanethiol, α-thioglycerol, and the like.
There is no restriction | limiting in particular in superposition | polymerization temperature, Although it can select suitably according to the objective, 50 to 150 degreeC is preferable and 60 to 100 degreeC is more preferable. The polymerization time is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 3 hours to 48 hours.

The obtained polymer is neutralized with either an alkali metal base or an organic amine base.
The neutralization treatment can be performed by neutralizing some or all of the phosphonic acid groups of the polymer with an alkali metal base or an organic amine base.
When neutralization has been completed in the monomer production process of general formula (3), this neutralization process can be omitted, but usually 1 to 2 equivalents are neutralized in the monomer production process, After polymerization, the remaining acid groups are neutralized.
The neutralization treatment of the alkali metal base or organic amine base can also be performed in a state where the pigment and the polymer are mixed in the ink production process.

More specifically, an aqueous solution in which the monomer represented by the general formula (3) is dissolved in a flask equipped with a stirrer, a thermometer, an inert gas (nitrogen or argon) introduction tube, and a condenser, and the general formula (4 ) And an organic solvent solution in which the monomer represented by (2) and a solution in which the polymerization initiator, the molecular weight modifier and the like are dissolved are batched or continuously stirred under an inert gas, and a temperature of 60 ° C. to 150 ° C. And then neutralizing with either an alkali metal base or an organic amine base.
The neutralization degree can be controlled by measuring the acid value of the resin in advance and performing neutralization treatment accordingly.
The acid value is measured by dissolving or dispersing the weighed resin in water, a water-soluble organic solvent or a mixed solvent thereof, and neutralizing and titrating with a potassium hydroxide methanol solution having a specified concentration using thymolphthalein as an indicator.
In the bisphosphonic acid compound of the present invention, it is known that three of the four acid groups are neutralized when the color of thymolphthalein changes (pH = 8 to 9). Therefore, when the acid value is obtained using thymolphthalein as an indicator and neutralized by adding a base accordingly, a structure in which three acid groups are neutralized can be prepared.
The obtained polymer (copolymer) has a molecular weight distribution depending on the degree of polymerization. Usually, the molecular weight can be easily measured by gel permeation chromatography (GPC), but the present polymer is a dissociative polymer and is difficult to measure due to adsorption to the GPC column.
Therefore, in the present invention, the viscosity when the polymer is a solution having a constant concentration is used as a substitute characteristic of molecular weight. In general, for the same type of polymer, there is a correlation between the molecular weight and the solution viscosity, and the higher the molecular weight, the higher the viscosity.
Viscosity is measured by preparing an aqueous solution having a concentration of 10% by mass and using a viscometer (RE500L, manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. while adjusting the sample viscosity to 50 or 100 rotations.
The preferred viscosity range of the polymer is 2-4 mPa · s. More preferably, it is 2-3 mPa * s. When it is less than 2, the calcium reactivity is lowered and the image density is liable to be lowered. When the polymer viscosity exceeds 3, the tendency of the pigment dispersibility to begin to decrease begins to appear. When the polymer viscosity exceeds 4, the ink viscosity increases and the storage stability decreases due to poor dispersion, and head clogging and ejection failure are likely to occur. Become.

The molecular weight of the polymer containing the structural units represented by the general formulas (1) and (2) can be controlled to some extent by the polymerization temperature, the polymerization initiator amount, and the monomer concentration during the reaction.
Regarding the polymerization temperature, a low molecular weight polymer tends to be obtained when polymerized in a short time at a high temperature, and a high molecular weight polymer tends to be easily obtained when polymerized over a long time at a low temperature.
As for the content of the polymerization initiator, a larger amount tends to obtain a low molecular weight polymer, and a smaller amount tends to obtain a high molecular weight polymer.
As for the monomer concentration during the reaction, a higher concentration tends to yield a polymer having a higher molecular weight, and a lower concentration tends to yield a polymer having a lower molecular weight.

(Inkjet recording ink)
The ink for inkjet recording of the present invention contains a copolymer containing water, a water-soluble organic solvent, a pigment, and a salt of a diphosphonic acid group having the structural unit of the general formula (1) and the general formula (2), It contains other components as necessary.

<Copolymer containing structural units represented by general formula (1) and general formula (2)>
The ink for inkjet recording of the present invention contains a polymer containing the structural unit represented by the general formula (1) and the general formula (2).
The polymer containing the structural units represented by the general formula (1) and the general formula (2) has a dibasic acid structure in which phosphonic acid groups are adjacent to each other. It has many diphosphonic acid groups. As a result, the polymer containing the structural unit represented by the general formula (1) and the general formula (2) can add more hydrophilic groups in the polymer molecule than the monobasic acid, and has good hydrophilicity. Indicates. Moreover, since it has a phosphonic acid group that easily reacts with Ca ions, and the phosphonic acid group is a dibasic acid, it has the effect of chelating Ca ions, and shows stronger bonds when contacted with Ca ions. Can be hydrophobized.
The structural unit represented by the general formula (2) brings moderate hydrophobicity to the polymer, improves wettability and adsorption with the pigment, and improves dispersion stability. Along with the hydrophilic phosphonic acid group of the general formula (1), there is a function of improving dispersibility while maintaining the cohesiveness of the resin when in contact with Ca ions. Although the reason is not clear, it has a function of preventing the association of phosphonic acid groups in the polymer, and has the effect of improving the storage stability in water-based ink.

These functions can be used as a dispersant.
Therefore, when the polymer containing the structural unit represented by the general formula (1) and the general formula (2) is used in the ink for ink jet recording, good ink dispersion stability and storage stability are exhibited. In addition, when the ink is printed on paper, the copolymer is hydrophobized by Ca ions eluted from the paper into the ink even if the plain paper has a small Ca ion content. Furthermore, since the structural unit represented by the general formula (2) has a high adsorptivity to the pigment, the pigment stays on the paper surface by aggregating and aggregating the pigment, and it becomes possible to realize a higher image density. .

  The content of the polymer containing the structural units represented by the general formula (1) and the general formula (2) in the ink for inkjet recording is not particularly limited and can be appropriately selected depending on the purpose. This content is solid content and is preferably 0.05% by mass to 10% by mass, more preferably 0.5% by mass to 5% by mass, and particularly preferably 1% by mass to 3% by mass. The effect of improving the image density is recognized when the content is 0.05% by mass or more. Moreover, when it is 10 mass% or less, it becomes possible to make it the viscosity range suitable when discharging ink from a head.

If the polymer containing the structural unit represented by the general formula (1) or the general formula (2) is used as a pigment dispersant, the image density in plain paper and the ink containing a large amount of the water-soluble organic solvent can be used. A further improvement in storage stability is observed.
The content of the polymer containing the structural units represented by the general formula (1) and the general formula (2) is not particularly limited when used as a pigment dispersant, and can be appropriately selected according to the purpose. it can. However, with respect to 100 parts by mass of the pigment, 1 part by mass to 100 parts by mass is preferable, 5 parts by mass to 80 parts by mass is more preferable, and 10 parts by mass to 50 parts by mass is still more preferable. When the content is within the more preferable range, it is advantageous in that a high image density is obtained and dispersion stability and storage stability are improved.

<Water>
As said water, pure water, such as ion-exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water can be used, for example.
There is no restriction | limiting in particular in content in the said ink for inkjet recording of the said water, According to the objective, it can select suitably.

<Pigment>
There is no restriction | limiting in particular as said pigment, According to the objective, it can select suitably, For example, the inorganic pigment, organic pigment, etc. for black or color are mentioned. These may be used alone or in combination of two or more.
Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, as well as a known method such as a contact method, a furnace method, and a thermal method. Carbon black can be used.

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 a phthalocyanine pigment, a perylene pigment, a perinone pigment, an anthraquinone pigment, a quinacridone pigment, a dioxazine pigment, an indigo pigment, a thioindigo pigment, an isoindolinone pigment, a quinofullerone pigment, and a rhodamine B lake pigment. Is mentioned.
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, the BET specific surface area of ^{50m 2 / g~300m 2 / g,} DBP oil absorption amount 40 mL / 100 g Those having ~ 150 mL / 100 g, volatile content of 0.5% to 10%, and pH of 2 to 9 are preferred.
As the carbon black, commercially available products can be used. 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).

  There is no restriction | limiting in particular as a pigment which can be used for yellow ink as the thing for said colors, According to the objective, it can select suitably, for example, C.I. 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.

  There is no restriction | limiting in particular as a pigment which can be used for a magenta ink, According to the objective, it can select suitably, For example, C.I. 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 in the cyan ink is not particularly limited and may be appropriately selected depending on the intended 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 used in the present invention may be newly produced for the present invention.
In addition, C.I. I. Pigment Yellow 74, C.I. I. Pigment red 122, C.I. I. Pigment Bio Red 19 and C.I. I. By using CI Pigment Blue 15: 3, a well-balanced ink having excellent color tone and light resistance can be obtained.

The volume average particle diameter (D50) of the pigment is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 150 nm or less, and more preferably 100 nm or less. When the volume average particle diameter (D50) is 150 nm or less, ejection stability is improved, and occurrence of nozzle clogging and ink bending may be prevented.
Here, the 50% average particle diameter of the pigment indicates a value of D50% measured by a dynamic light scattering method with Microtrac UPA manufactured by Nikkiso Co., Ltd. in an environment of 23 ° C. and 55% RH.

  The content of the pigment in the ink for inkjet recording is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1% by mass to 20% by mass, and 1% by mass to 20% by mass. More preferred.

  The pigment is preferably mixed with water, a pigment, and, if necessary, a dispersant, dispersed with a disperser to adjust the particle size, and then the pigment dispersion is contained in the ink.

The pigment dispersion is obtained by mixing water, a pigment, a pigment dispersant, and, if necessary, other components, and then dispersing the mixture with a disperser and adjusting the particle size.
The obtained pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifugal separator or the like, if necessary.

There is no restriction | limiting in particular in content of the pigment at the time of producing the said pigment dispersion, Although it can select suitably according to the objective, 0.1 mass%-50 mass% are preferable, 0.1 mass%- 30 mass% is more preferable.
The pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifugal separator or the like, if necessary.

The pigment dispersant in the pigment dispersion is preferably a polymer containing a structural unit represented by the general formula (1). Other usable dispersants include, for example, various surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, naphthalenesulfonic acid Na formalin condensate, polymer type And the like.
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 taurates, polyoxyalkyl ethers. Sulfate, polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate, lauryl alcohol sulfate, alkylphenol phosphate, naphthalenesulfonate formalin condensate, alkyl phosphate, alkylallylsulfone hydrochloride, Examples include diethylsulfosuccinate, diethylhexylsulfosuccinate, dioctylsulfosuccinate, and the like.
Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.
Examples of the amphoteric surfactant include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, And imidazoline derivatives.
Examples of the nonionic surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ether, Ether type surfactants such as oxyallylalkyl alkyl ethers; polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate Ester surfactants such as polyoxyethylene monooleate and polyoxyethylene stearate; 2,4,7,9-tetramethyl Acetylene glycol surfactants such as lu-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyn-3-ol, Etc.
Among these, naphthalenesulfonic acid Na formalin condensate is particularly preferable.
The total content of dimers, trimers and tetramers of naphthalenesulfonic acid in the naphthalenesulfonic acid Na formalin condensate is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 20% by mass to 80% by mass. When the content is 20% by mass or more, the dispersibility is improved and the storage stability of the ink is improved. As a result, the occurrence of nozzle clogging can be prevented. On the other hand, when the content is 80% by mass or less, the viscosity range of the ink is appropriate and the dispersibility may be good.

<Water-soluble organic solvent>
The water-soluble organic solvent has at least one of an effect as a wetting agent for preventing ink drying and an effect as a penetrating agent.

There is no restriction | limiting in particular as said water-soluble organic solvent, According to the objective, it can select suitably.
For example, glycerin, ethylene glycol, diethylene glycol, isopropylideneglycerol, 1,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, trimethylolethane, Ethylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,2,6-hexanetriol, Polyhydric alcohols such as 1,2,4-butanetriol, 1,2,3-butanetriol, and petriol; ethylene glycol monoethyl ester Polyhydric alcohol alkyl ethers such as ter, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene glycol monophenyl ether, ethylene glycol monobenzyl Polyhydric alcohol aryl ethers such as ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone, etc. Nitrogen-containing heterocyclic compounds; formamide, N-methylformamide, N, N-dimethylformamide, N, N-dimethyl- Amides such as methoxypropionamide and N, N-dimethyl-β-butoxypropionamide; amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine; dimethyl sulfoxide, sulfolane, thiodiethanol and the like Sulfur-containing compounds: 3-ethyl-3-hydroxymethyloxetane, propylene carbonate, ethylene carbonate, and the like.
These may be used individually by 1 type and may use 2 or more types together.
Of these, 3-ethyl-3-hydroxymethyloxetane, isopropylideneglycerol, N, N-dimethyl-β-methoxypropionamide, N, N-dimethyl-β-butoxy are preferred because they prevent curling on plain paper. Propionamide is particularly preferred.

  In addition, 1,3-butanediol, diethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol, and glycerin are excellent in preventing discharge failure due to moisture evaporation.

  Examples of the water-soluble organic solvent having relatively low wettability and permeability include 2-ethyl-1,3-hexanediol [solubility: 4.2% (25 ° C.)], 2, 2, 4 -Trimethyl-1,3-pentanediol [solubility: 2.0% (25 ° C)], and the like.

As other polyol compounds, as aliphatic diols, for example, 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1, 3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene- 1,2-diol, and the like.
Other penetrants that can be used in combination are not particularly limited as long as they can be dissolved in the ink and adjusted to desired physical properties, and can be appropriately selected according to the purpose.
For example, alkyl and aryl ethers of polyhydric alcohols such as diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl ether, And lower alcohols such as ethanol.

In addition, saccharides can be contained as a wetting agent that is not a water-soluble organic solvent. Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and the like. Specific examples include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include a substance that exists widely in nature such as α-cyclodextrin and cellulose. The derivatives of these saccharides are represented by the reducing sugars of the saccharides described above [for example, sugar alcohol [general formula: HOCH ₂ (CHOH) _n CH ₂ OH (where n represents an integer of 2 to 5)). The ], Oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, thioic acids and the like. Among these, sugar alcohol is preferable, and examples of the sugar alcohol include maltitol and sorbit.

The ratio of the pigment to the water-soluble organic solvent has a great influence on the ink ejection stability from the head. If the content of the water-soluble organic solvent is low even though the pigment solid content is high, the evaporation of water near the ink meniscus of the nozzle may progress and cause ejection failure.
The content of the water-soluble organic solvent in the inkjet recording ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass to 60% by mass, and more preferably 20% by mass to 60% by mass. Is more preferable. When the content is 10% by mass or more, the ink ejection stability may be improved, and when it is 60% by mass or less, the drying property may be improved. The ink having the content in the more preferable numerical range has an advantage that the drying property and the ejection reliability are very good.

<Other ingredients>
There is no restriction | limiting in particular as said other component, It can select suitably as needed, For example, surfactant, pH adjuster, water-dispersible resin, antiseptic / antifungal agent, rust inhibitor, antioxidant , Ultraviolet absorbers, oxygen absorbers, light stabilizers, and the like.

-Surfactant-
The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, fluorine-based surfactants Agents, etc. Among these, nonionic surfactants and fluorine surfactants are particularly preferable.

  Examples of the anionic surfactant include alkyl allyl, alkyl naphthalene sulfonate, alkyl phosphate, alkyl sulfate, alkyl sulfonate, alkyl ether sulfate, alkyl sulfosuccinate, alkyl ester sulfate, and alkylbenzene. Sulfonate, alkyl diphenyl ether disulfonate, alkyl aryl ether phosphate, alkyl aryl ether sulfate, alkyl aryl ether ester sulfate, olefin sulfonate, alkane olefin sulfonate, polyoxyethylene alkyl ether phosphate, Polyoxyethylene alkyl ether sulfate ester salt, ether carboxylate, sulfosuccinate, α-sulfo fatty acid ester, fatty acid salt, condensate of higher fatty acid and amino acid, naphthene Salt, and the like.

  Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalkonium salts, quaternary ammonium salts, alkylpyridinium salts, imidazolinium salts, sulfonium salts, phosphonium salts, Etc.

  Examples of the nonionic surfactant include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like.

  Examples of the amphoteric surfactant include imidazoline derivatives such as imidazolinium betaine, dimethylalkyl lauryl betaine, alkyl glycine, alkyl di (aminoethyl) glycine, and the like.

  Examples of the fluorine-based surfactant include compounds represented by the following general formulas (I) to (III).

ただし、前記一般式（Ｉ）中、ｍは、０〜１０の整数を表す。ｎは、１〜４０の整数を表す。

However, in the said general formula (I), m represents the integer of 0-10. n represents an integer of 1 to 40.

前記一般式（II）において、Ｒｆはフッ素含有基を表し、パーフルオロアルキル基が好ましい。
前記パーフルオロアルキル基としては、炭素数が１〜１０のものが好ましく、１〜３のものがより好ましく、例えば、−Ｃ_ｎＦ_２ｎ−１（ただし、ｎは１〜１０の整数を表す）などが挙げられる。前記パーフルオロアルキル基としては、例えば、−ＣＦ_３、−ＣＦ_２ＣＦ_３、−Ｃ_３Ｆ_７、−Ｃ_４Ｆ_９、などが挙げられる。これらの中でも、−ＣＦ_３、−ＣＦ_２ＣＦ_３が特に好ましい。
ｍ、ｎ、及びｐは、それぞれ整数を表し、ｎは１〜４、ｍは６〜２５、ｐは１〜４が好ましい。

In the general formula (II), Rf represents a fluorine-containing group, preferably a perfluoroalkyl group.
Examples of the perfluoroalkyl group preferably has a carbon number of 1 to 10, more preferably those of 1 to 3, for _example, -C _{n F 2n-1} (where, n is an integer of 1 to 10) Etc. Examples of the perfluoroalkyl group, _{e.g., -CF 3, -CF 2 CF 3} , -C 3 F 7, -C 4 F 9, and the like. Among these, —CF ₃ and —CF ₂ CF ₃ are particularly preferable.
m, n, and p each represent an integer, n is preferably 1-4, m is preferably 6-25, and p is preferably 1-4.

In the general formula (III), Rf represents a fluorine-containing group, and is preferably a perfluoroalkyl group similar to the above general formula (II). For example, CF ₃ , CF ₂ CF ₃ , C ₃ F ₇ , C ₄ such as F ₉ are preferably exemplified.
R ₂ ⁺ represents a cationic group, and examples thereof include quaternary ammonium groups; alkali metal ions such as sodium and potassium; triethylamine, triethanolamine, and the like. Among these, a quaternary ammonium group is particularly preferable. R ₁ ⁻ represents an anionic group, and examples thereof include COO ⁻ , SO ₃ ⁻ , SO ₄ ⁻ and PO ₄ ⁻ . q is preferably 1-6.

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F1405 , F-474 (all manufactured by DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont); FT-110 , FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Corporation); PF-151N (Solue) ®-made lens Inc. Co., Ltd.) and the like. Among these, Zonyl FS-300, FSN, FSN-100, and FSO (all manufactured by DuPont) are particularly preferable from the viewpoint of improving reliability and color developability.

  The content of the surfactant in the inkjet recording ink is not particularly limited and can be appropriately selected depending on the purpose. However, 0.01 mass%-5.0 mass% are preferable, and 0.5 mass%-3 mass% are more preferable. When the content is 5.0% by mass or less, the permeability to the recording medium is improved, and it may be possible to prevent a decrease in image density and occurrence of show-through.

-PH adjuster-
The pH adjuster is not particularly limited as long as the pH can be adjusted to 8.5 to 11 without adversely affecting the prepared ink, and can be appropriately selected depending on the purpose. For example, alcohol amines, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates, and the like can be given.
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 forming properties) and has high water repellency, high water resistance, and high weather resistance, and is used for image recording with high water resistance and high image density (high color development). Useful.
Examples of the water-dispersible resin include condensation-type synthetic resins, addition-type synthetic resins, and natural polymer compounds.
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, natural rubber, and the like.
Among these, polyurethane resin fine particles, acrylic-silicone resin fine particles, and fluorine-based resin fine particles are preferable.

The average particle size (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 size decreases.
The average particle diameter (D50) of the water-dispersible resin is not particularly limited so that the ink does not have an excessively high viscosity, and can be appropriately selected according to the purpose, but is preferably 50 nm or more.
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 average particle diameter (D50) is more preferably 200 nm or less in order not to disturb the ink ejection stability.
The water-dispersible resin has a function of fixing the water-dispersed colorant on the paper surface, and is preferably formed into a film at room temperature to improve the fixability of the color material.
Therefore, the minimum film-forming temperature (MFT) of the water-dispersible resin is not particularly limited and can be appropriately selected according to the purpose, but is preferably 30 ° C. or lower.
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.
The content of the water-dispersible resin in the inkjet recording ink is not particularly limited and may be appropriately selected depending on the intended purpose. However, the solid content is preferably 1% by mass to 15% by mass, and preferably 2% by mass. -7 mass% is more preferable.

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

-Antirust agent-
Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and the like.

-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.

<Method for producing ink for inkjet recording>
The ink jet recording ink production method of the present invention includes, for example, water, a water-soluble organic solvent, a pigment, a polymer containing the structural unit represented by the above (Formula 1) and (Formula 2), and other if necessary It can be produced by dispersing or dissolving the components in an aqueous medium and stirring and mixing them.
The ink is preferably degassed by filtering coarse particles with a filter, a centrifugal separator or the like, if necessary.
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.

<Ink physical properties>
The physical properties of the ink for ink jet recording of the present invention are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity, surface tension and the like are preferably in the following ranges.
There is no restriction | limiting in particular in the viscosity at 25 degrees C of the said ink for inkjet recording, Although it can select suitably according to the objective, 3 mPa * s-20 mPa * s are preferable. When the ink viscosity is 3 mPa · s or more, the effect of improving the printing density and the character quality can be obtained. On the other hand, by setting the ink viscosity to 20 mPa · s or less, it is often possible to ensure ink ejection.
There is no restriction | limiting in particular as surface tension of the said ink for inkjet recording, Although it can select suitably according to the objective, 40 mN / m or less is preferable at 25 degreeC.

-Ink viscosity-
The viscosity of the black ink and color ink of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. The viscosity at 25 ° C. is preferably 2.0 mPa · s to 30 mPa · s, and the above Thus, 3 mPa · s to 20 mPa · s is more preferable. The viscosity can be measured using, for example, a viscometer RE500L manufactured by Toki Sangyo Co., Ltd.

(Inkjet recording method and inkjet recording apparatus)
The ink jet recording apparatus of the present invention is characterized by having ink ejecting means for recording an image on a recording medium by ejecting the ink for ink jet recording of the present invention from a recording head. That is, the ink jet recording apparatus of the present invention includes at least a recording head and a maintenance / recovery device, and further includes other means such as a stimulus generating means and a control means as necessary.

  The ink jet recording method of the present invention includes at least an ink flying process of applying a stimulus to the ink jet recording ink of the present invention via an ink flying means and causing the ink to fly from a recording head to record an image on a recording medium. It is characterized by this. That is, the ink jet recording method 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.

Hereinafter, the details of the ink jet recording method of the present invention will be described through the description of the ink jet recording apparatus of the present invention.
The ink jet recording apparatus records an image by applying a stimulus to each ink of the present invention via an ink flying means and ejecting the ink from the nozzle of the recording head. 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 heating device, a pressurizing device, a piezoelectric element, a vibration generating device, an ultrasonic oscillator, and a light. For example, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change due to film boiling of a liquid using an electrothermal transducer such as a heating resistor, a shape memory alloy actuator that uses a metal phase change due to a temperature change, an electrostatic force Examples include electrostatic actuators to be used.

There are no particular restrictions on the manner in which the recording ink flies, and it may vary depending on the type of stimulation. For example, when the stimulus is “heat”, thermal energy corresponding to a recording signal is applied to the recording ink in the recording head using, for example, a thermal head, and bubbles are generated in the recording ink by the thermal energy. And the recording ink is ejected and ejected as droplets from the nozzle holes of the recording head by the pressure of the bubbles. 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 the recording ink is ejected and ejected as droplets from the nozzle holes of the recording head.
The size of the recording ink droplets to be ejected is preferably 3 to 40 pl, for example. The discharge jet speed is preferably 5 to 20 m / s, the drive frequency is preferably 1 kHz or more, and the resolution is preferably 300 dpi or more.
The recording head preferably includes a number of nozzles, and has either a head unit or a recording unit that discharges ink in the ink set into ink droplets by the action of energy. Further, the recording head includes a liquid chamber portion, a fluid resistance portion, a diaphragm, and a nozzle member, and at least a part of the recording head is made of a material containing any one of silicone and nickel. Preferably it is formed. The nozzle diameter of the recording head is preferably 30 μm or less, and more preferably 1 to 20 μm.

The ink jet recording apparatus of the present invention preferably has a sub tank for supplying ink onto the recording head, and the sub tank is replenished with ink from an ink cartridge through a supply tube.
The maintenance recovery device covers at least one suction cover means (suction cap) that covers the recording head and communicates with the suction force generation means, and at least one suction cover means that covers the recording head and does not communicate with the suction force generation means Non-suction cover means (moisturizing cap) is provided, and other means are provided as necessary. Thus, by providing the suction cap and the moisture retention cap, the amount of ink consumed for the maintenance operation for ensuring reliability is less than the configuration in which all caps are suction caps, and the time required for the maintenance operation, Ink waste can be prevented. The maintenance / recovery device is not particularly limited and may be appropriately selected depending on the intended purpose. For example, those described in JP-A-2005-170035 may be used.

The ink jet recording apparatus of the present invention preferably has a reversing unit that can perform double-sided printing by reversing the recording surface of the recording medium. Examples of the reversing means include a conveyance belt having electrostatic force, a means for holding a recording medium by air suction, and a combination of a conveyance roller and a spur. It is preferable to have an endless conveying belt and conveying means for conveying the surface of the conveying belt while charging and holding the recording medium. In this case, it is particularly preferable to charge the conveying belt by applying an AC bias of ± 1.2 kV to ± 2.6 kV to the charging roller.
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, FIG. 1 and FIG. 2 are schematic plan views as seen from the nozzle surface showing an example of a recording head provided in the ink jet recording apparatus of the present invention. FIG. 1 shows a two-head type composed of a first head and a second head. FIG. 2 shows a four-head type including a first head, a second head, a third head, and a fourth head.
In the two-head type, either the first head or the second head is covered with a suction cover means (suction cap) communicating with the suction force generation means, and the other is not suctioned with no communication with the suction force generation means It is covered with a covering means (moisturizing cap). In the example of FIG. 1, the first head is covered with a suction cap, and the second head is covered with a moisture retention cap.

In the four-head type shown in FIG. 2, at least one of the first to fourth heads is covered with a suction cover means (suction cap) communicating with the suction force generation means, and the others are in communication with the suction force generation means. It is covered with non-suction cover means (moisturizing cap) that is not. In the example of FIG. 2, the first head is covered with a suction cap, and the second, third, and fourth heads are covered with a moisture retention cap.
In the two-head type shown in FIG. 1, when full-color recording is performed, yellow (Y), cyan (C), magenta (M), and black (Bk) inks are applied to a total of four nozzle rows. Each needs to be filled.

Here, an example of the ink jet recording apparatus of the present invention having the maintenance / recovery apparatus will be described with reference to FIG. FIG. 3 is an explanatory perspective view of the ink jet recording apparatus as viewed from the front side.
An ink jet recording apparatus shown in FIG. 3 includes an apparatus main body 1, a paper feed tray 2 for loading paper loaded in the apparatus main body 1, and a paper (recording medium) loaded in the apparatus main body 1 on which an image is recorded (formed). ) And a cartridge loading portion 6 that protrudes forward from the front surface 4 and is lower than the upper surface 5 on one end side of the front surface 4 of the apparatus main body 1. . An operation unit 7 such as operation keys and a display is disposed on the upper surface of the cartridge loading unit 6. A main tank (hereinafter referred to as “ink cartridge”) 10 that is a liquid storage tank as a liquid replenishing unit is replaceably mounted on the cartridge loading unit 6, and has a front cover 8 that can be opened and closed. .
Here, the ink cartridge is formed by containing the ink for ink jet recording of the present invention in a container, and may further comprise 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.

  For example, after the ink cartridge is filled into the ink bag from the ink inlet and exhausted, the ink inlet is closed by fusion. In use, the needle of the apparatus main body is pierced into an ink discharge port made of a rubber member and supplied to the apparatus. The ink bag is formed of a packaging member such as a non-permeable aluminum laminate film. The ink bag is usually housed in a plastic cartridge case and is detachably mounted on various ink jet recording apparatuses.

Next, the mechanism part of the ink jet recording apparatus of FIG. 3 will be described with reference to FIGS. 4 is a schematic configuration diagram for explaining the overall configuration of the mechanism unit, and FIG.
A carriage 33 is slidably held in the main scanning direction by a guide rod 31 which is a guide member horizontally mounted on the left and right side plates 21A and 21B constituting the frame 21 and a stay 32, and carriage scanning in FIG. 3 is performed by a main scanning motor. Move and scan in the direction (main scanning direction).
In the carriage 33, a plurality of recording heads 34, which are ink jet heads that are droplet ejection heads for ejecting ink droplets (ink droplets), are arranged in a direction crossing a plurality of nozzles with the main scanning direction, The ink droplet is ejected in the downward direction.
Here, the recording head 34 includes, for example, a recording head 34y that discharges yellow (Y) droplets, a recording head 34m that discharges magenta (M) droplets, and a recording head that discharges cyan (C) droplets. 34c, and a recording head 34k that discharges black (Bk) droplets. The “recording head 34” does not distinguish between colors. The head configuration is not limited to these examples, and it may be configured using one or a plurality of recording heads having one or a plurality of nozzle rows that eject droplets of one or a plurality of colors. .

  The droplet discharge head constituting the recording head 34 includes a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by liquid film boiling 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 discharging droplets can be used.

  Also, the carriage 33 is equipped with sub-tanks 35y, 35m, 35c, and 35k for each color for supplying ink of each color to each recording head 34 (referred to as “sub-tank 35” when colors are not distinguished). Ink is supplied to the sub tank 35 from the ink cartridges 10 of the respective colors (referred to as “ink cartridges 10y, 10m, 10c, 10k” when different colors are distinguished) through the ink supply tubes 37 of the respective colors. I am doing so.

Here, the ink cartridge 10 is stored in the cartridge loading unit 6 as shown in FIG. The cartridge loading unit 6 is provided with a supply pump unit 23 for feeding ink in the ink cartridge 10. Further, the ink supply tube 37 from the ink cartridge loading section 6 to the sub tank 35 is fixed and held by the main body side holder 25 on the rear plate 21C constituting the frame 21 in the middle of rolling. Further, it is fixed on the carriage 33 by the fixing rib 26.
4 and 5, reference numeral 22 denotes a flexible cable, and reference numeral 36 denotes an ink supply tube (sub tank connecting portion).

On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (bottom plate) 41 of the paper feed tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. Paper separation roller 44 and separation pad 44 made of a material having a large friction coefficient are provided. The separation pad 44 is urged toward the paper feed roller 43 side.
As a transport unit for transporting the paper 42 fed from the paper feed unit on the lower side of the recording head 34, a transport belt 51 for transporting the paper 42 by electrostatic adsorption, and a paper feed unit The counter roller 52 for transporting the paper 42 fed through the guide 45 while sandwiching it between the transport belt 51 and the paper 42 fed substantially vertically upward are changed by approximately 90 ° and copied onto the transport belt 51. A conveying guide 53 for adjusting the pressure and a tip pressing roller 55 urged toward the conveying belt 51 by a pressing member 54. In addition, a charging roller 56 that is a charging unit for charging the surface of the conveyance belt 51 is provided.
Here, the conveyance belt 51 is an endless belt, and is configured to be looped around the conveyance roller 57 and the tension roller 58 in the belt conveyance direction of FIG. The charging roller 56 is disposed so as to contact the surface layer of the conveyor belt 51 and rotate following the rotation of the conveyor belt 51, and applies 2.5N to both ends of the shaft as pressure.
In addition, a guide member 61 is disposed on the back side of the conveyance belt 51 so as to correspond to a printing area by the recording head 34. The upper surface of the guide member 61 protrudes closer to the recording head 34 than the tangent line of the two rollers (the conveyance roller 57 and the tension roller 58) that support the conveyance belt 51. As a result, the conveyance belt 51 is pushed up and guided by the upper surface of the guide member 61 in the printing region, so that highly accurate flatness is maintained.

Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 71 for separating the paper 42 from the transport belt 51, a paper discharge roller 72, and a paper discharge roller 73 are provided. A paper discharge tray 3 is provided below the paper discharge roller 72. Here, the height from between the paper discharge roller 72 and the paper discharge roller 73 to the paper discharge tray 3 is increased to some extent in order to increase the amount that can be stored in the paper discharge tray 3.
A double-sided paper feeding unit 81 is detachably attached to the back surface of the apparatus body 1. The double-sided paper feed unit 81 takes in the paper 42 returned by the reverse rotation of the transport belt 51, reverses it, and feeds it again between the counter roller 52 and the transport belt 51. A manual paper feed unit 82 is provided on the upper surface of the duplex paper feed unit 81.

  Further, as shown in FIG. 5, in a non-printing area on one side of the carriage 33 in the scanning direction, a maintenance / recovery device (hereinafter referred to as “sub-system”) for maintaining and recovering the nozzle state of the recording head 34. 91 is also provided. The sub-system 91 includes cap members (hereinafter also referred to as “caps”) 92a to 92d for capping each nozzle surface of the recording head 34 (referred to as “caps 92” when not distinguished). A wiper blade 93 that is a blade member for wiping the nozzle surface, and an empty space that receives a droplet when performing an empty discharge that discharges a droplet that does not contribute to recording in order to discharge the thickened ink. A wiper cleaner 95 (see FIG. 7), which is formed integrally with the discharge receiver 94 and the idle discharge receiver 94 and removes ink adhering to the wiper blade 93, and the wiper blade 93 when the wiper blade 93 is cleaned. A cleaner roller 96 that constitutes a cleaner means to be pressed against the wiper cleaner 95 side is provided. .

  Further, as shown in FIG. 5, in the non-printing area on the other side in the scanning direction of the carriage 33, idle discharge is performed to discharge liquid droplets that do not contribute to recording in order to discharge ink that has been thickened during recording or the like. An empty discharge receiver 98 for receiving the droplet of the time is arranged. The idle discharge receiver 98 is provided with an opening 99 and the like along the nozzle row direction of the recording head 34.

In the ink jet recording apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feeding tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide 45, and the transport belt 51 and the counter roller 52 to be conveyed between the two. Further, the front end of the paper 42 is guided by the transport guide 53 and pressed against the transport belt 51 by the front end pressure roller 55, and the transport direction is changed by approximately 90 °.
At this time, a positive voltage and a negative output are alternately repeated from the high voltage power source to the charging roller 56 by the control circuit, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 51 alternates, that is, a rotating direction. In the sub-scanning direction, plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 42 is fed onto the conveyance belt 51 charged alternately with plus and minus, the sheet 42 is electrostatically attracted to the conveyance belt 51, and the sheet 42 is moved in the sub-scanning direction by the circular movement of the conveyance belt 51. Be transported. Therefore, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 is conveyed by a predetermined amount, the next Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  Further, during printing (recording) standby, the carriage 33 is moved to the subsystem 91 side, the recording head 34 is capped by the cap member 92, and the nozzles are kept in a wet state to prevent ejection failure due to ink drying. . Further, a recovery operation is performed in which ink is sucked from the nozzles (referred to as “nozzle suction” or “head suction”) while the recording head 34 is capped by the cap member 92 and the thickened ink and bubbles are discharged. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. As a result, the stable ejection performance of the recording head 34 is maintained.

Next, an outline of the configuration of the subsystem 91 including the maintenance / recovery device in the inkjet recording apparatus of the present invention will be described with reference to FIGS. 6 is an explanatory plan view of the main part of the system, FIG. 7 is a schematic schematic configuration diagram of the system, and FIG. 8 is an explanatory diagram on the right side of FIG.
A frame (maintenance device frame) 111 of the subsystem 91 includes two cap holders 112A and 112B as a cap holding mechanism, a wiper blade 93 as a wiping member including an elastic body as a cleaning means, and a carriage lock 115. Are held up and down (movable up and down). An empty discharge receiver 94 is disposed between the wiper blade 93 and the cap holder 112A. Further, in order to clean the wiper blade 93, the cleaner means includes a cleaner roller 96 which is a cleaning member for pressing the wiper blade 93 from the outside of the frame 111 to the wiper cleaner 95 side which is a cleaning member of the idle discharge receiver 94. The wiper cleaner 118 is swingably held.

The cap holders 112A and 112B (referred to as “cap holder 112” when not distinguished from each other) hold two caps 92a and 92b and caps 92c and 92d for capping the nozzle surfaces of the two recording heads 34, respectively. .
Here, a tubing pump (suction pump) 120 as a suction means is connected to the cap 92a held by the cap holder 112A closest to the printing area via a flexible tube 119, and the other caps 92b, 92c, 92d does not connect the tubing pump 120. That is, only the cap 92a is used as a suction (recovery) and moisturizing cap (hereinafter also referred to as “suction cap”), and the other caps 92b, 92c, 92d are all used as mere moisturizing caps. Therefore, when performing the recovery operation of the recording head 34, the recording head 34 that performs the recovery operation is selectively moved to a position where it can be capped by the suction cap 92a.

A cam shaft 121 rotatably supported by the frame 111 is disposed below the cap holders 112A and 112B. Cap cams 122A and 122B for raising and lowering the cap holders 112A and 112B are disposed on the cam shaft 121. A wiper cam 124 for raising and lowering the wiper blade 93, a carriage lock cam 125 for raising and lowering the carriage lock 115 via the carriage lock arm 117, and an empty liquid droplet that is idlely discharged in the idle discharge receiver 94. A roller 126 as a rotating body, which is a discharge landing member, and a cleaner cam 128 for swinging the wiper cleaner 118 are provided.
Here, the cap 92 is moved up and down by the cap cams 122A and 122B. The wiper blade 93 is moved up and down by the wiper cam 124, and the wiper cleaner 118 is advanced when the wiper blade 124 is lowered. Ink adhering to 93 is scraped off into the empty ejection receiver 94.

The carriage lock 115 is urged upward (in the locking direction) by a compression spring, and is raised and lowered via a carriage lock arm 117 driven by a carriage lock cam 125.
In order to rotationally drive the tubing pump 120 and the cam shaft 121, the rotation of the motor 131 is meshed with the motor gear 132 provided on the motor shaft 131 a and the pump gear 133 provided on the pump shaft 120 a of the tubing pump 120. Further, an intermediate gear 136 with a one-way clutch 137 is engaged with an intermediate gear 134 integral with the pump gear 133 via an intermediate gear 135. The cam gear 140 fixed to the camshaft 121 via the intermediate gear 139 is engaged with the intermediate gear 138 coaxial with the intermediate gear 136. An intermediate shaft 141 that is a rotation shaft of the intermediate gears 136 and 138 with the clutch 137 is rotatably held by the frame 111.

The cam shaft 121 is provided with a home position sensor cam 142 for detecting the home position, and the home position lever is operated when the cap 92 comes to the lowest end by the home position sensor provided in the subsystem 91. Then, the sensor is opened and the home position of the motor 131 (other than the pump 120) is detected. Note that when the power is turned on, the position moves up and down (up and down) regardless of the position of the cap 92 (cap holder 112), the position is not detected until the movement starts, and the position is determined after detecting the home position of the cap 92 (on the way up). To the bottom end. Thereafter, the carriage moves left and right, returns to the cap position after position detection, and the recording head 34 is capped.
Reference numeral 142 denotes a home position sensor cam.

Next, details of the holding mechanism and the lifting mechanism (vertical movement mechanism) of the cap 92 will be described with reference to FIG. FIG. 9 is an explanatory side view of the cap holding lifting mechanism.
The cap holder 112A, which is a cap holding mechanism, includes a holder 151 that holds the cap 92a and the cap 92b (sometimes collectively referred to as “cap 92A”) so as to be movable up and down, a bottom surface of the holder 151, and a bottom portion of the cap 92A. And a slider 152 that holds the holder 151 movably in the front-rear direction (the direction in which the nozzles of the recording head 34 are arranged).
The cap 92A is inserted into the guide groove 150 (not shown) of the holder 151 so that the guide pins 150a provided at both ends can be moved up and down, and the guide shaft 150b provided on the bottom surface is inserted into the holder 151 so as to be movable up and down. It is mounted so that it can move up and down. The springs 152, 152 interposed between the cap 92A and the cap holder 151 urge the caps 92a, 92b upward (in the direction of pressing toward the nozzle surface when capping).

  The slider 153 is configured such that the guide pins 154 and 155 provided at the front and rear ends are slidably fitted in guide grooves 156 formed in the frame 111 so that the slider 153, the holder 151, and the cap 92A can be moved up and down.

Then, the cam pin 157 provided on the lower surface of the slider 153 is fitted in a cam groove (not shown) of the cap cam 122A, and the slider 153 is rotated by the rotation of the cap cam 122A that is synchronized with the rotation of the cam shaft 121 to which the rotation of the motor 131 is transmitted. The holder 151 and the cap 92A move up and down.
Further, the slider 153 and the holder 151 are inserted into the suction cap 92a, and the tube 119 is wound around and connected from below the center position of the cap in the short direction of the cap 92a.
Note that the cap holder 112B for holding the caps 92c and 92d (which may be collectively referred to as “cap 92B”) and the configuration for moving the cap holder 112B up and down are the same as described above, and thus the description thereof is omitted. However, the tube 119 is not connected to the caps 92c and 92d. As described above, the cam shaft 121 as one shaft rotates by driving the motor 131 as one drive source. The cams 122A and 122B fixed to the cam shaft 121 are rotated by the rotation of the cam shaft 121, and the cap 92A and the cap 92B move up and down.

  The ink jet recording apparatus and the ink jet recording method of the present invention can be applied to various recordings by an ink jet recording method. For example, the present invention can be particularly suitably applied to an inkjet recording printer, a facsimile machine, a copying machine, a printer / fax / copier multifunction machine, and the like.

-Ink recordings-
The ink recorded matter recorded by the ink jet recording method of the present invention is the ink recorded matter of the present invention. The ink recorded matter of the present invention has an image recorded on the recording medium by the ink recording ink of the present invention.
The recording medium used in the present invention is not particularly limited as long as the ink for ink jet recording of the present invention is landed and an image can be formed. For example, plain paper, coated paper for printing, glossy paper, special paper and the like can be mentioned.
The paper exemplified above contains calcium carbonate, talc, kaolin, aluminum sulfate (sulfuric acid band), and the like. When the ink jet recording ink of the present invention lands on the paper, a polyvalent metal ion, specifically In the sample, divalent or trivalent metal ions such as calcium, magnesium and aluminum are eluted.
The ink for ink jet recording in the present invention reacts with the above polyvalent metal ions to aggregate the pigment, and a high image density can be obtained. However, it has been difficult to achieve high image density with plain paper among the papers exemplified above.
Many of the fillers and sizing agent fixing agents contained in plain paper are poorly water-soluble metal salts. Moreover, even if a water-soluble metal salt is contained, the content is small. Therefore, plain paper has less elution of polyvalent metal ions compared to paper processed with water-soluble polyvalent metal salt or the like on the paper surface, and the prior art cannot provide an effect of improving image density.
In the present invention, a high image density can be realized not only on the processed paper but also on paper with less elution of polyvalent metal ions such as plain paper. Examples of commercially available plain paper include high-quality paper My Paper (manufactured by Ricoh Co., Ltd.), Xerox 4024 (manufactured by Fuji Xerox Co., Ltd.), and the like.

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 ^{−4 to} 5.0 × 10 ⁻⁴ [g / g]. When the Ca ion amount is 1.0 × 10 ⁻⁴ [g / g] or more, the effect of improving the image density by reaction aggregation with the pigment dispersant is improved. Further, since the Ca ion amount is 5.0 × 10 ⁻⁴ [g / g] or less, the ink permeation 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.
The amount of Ca ions eluted from the paper is calculated by the following method. That is, the paper is filtered into a 2.5 cm (± 0.5 cm) × 3.5 cm (± 0.5 cm) square piece of paper, and the pure water is filtered through a 0.8 μm cellulose acetate filter (manufactured by Advantech Co., Ltd.). Then, the Ca ions contained in the immersion liquid are quantified by an ICP emission spectroscopic analyzer. 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.
For example, the amount of Ca ions of MyPaper (manufactured by Ricoh Co., Ltd.) is 4.3 × 10 ⁻⁴ [g / g], and the amount of Ca ions of Xerox 4024 (manufactured by Fuji Xerox Co., Ltd.) is 1.7 × 10 ⁻⁴ [ g / g].

  Examples of the present invention will be described below, but the present invention is not limited to the following examples. “Part” represents “part by mass” unless otherwise specified. “%” Represents “% by mass” unless otherwise specified.

<Synthesis of monomer>
[Monomer No. 1: 4-Methacrylamide-1-hydroxybutane-1,1-diphosphonic acid disodium salt]
Put 25 parts of alendronic acid (manufactured by Tokyo Kasei Kogyo Co., Ltd.) into the flask, and then add an aqueous solution in which 17.1 parts of sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.) was dissolved in 200 parts of ion-exchanged water. Dissolved in. Next, 13.32 parts of methacrylic acid chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) was slowly added dropwise while cooling the flask to 5 ° C. After completion of the dropwise addition, the mixture was further stirred for 30 minutes, and then 14.53 parts of concentrated hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise while cooling. The reaction solution was extracted and washed with methylene chloride three times, and the remaining aqueous solution was dropped into 800 parts of methanol to precipitate the desired product. Filtration gave 35 parts of the desired product.
1.7 parts of this product was dissolved in 176 parts of ion-exchanged water, neutralized and titrated with 0.1N KOH methanol solution using thymolphthalein (manufactured by Kanto Chemical Co.) as an indicator, and the acid value was determined to be 155. . Comparison with the alendronic acid titration results agreed well with the calculated value 155 when two of the OH groups of phosphonic acid were replaced by Na salts.

[Monomer No. 2: 4-acrylamido-1-hydroxybutane-1,1-diphosphonic acid disodium salt]
Monomer No. Instead of using 13.32 parts of methacrylic acid chloride in the synthesis of 1, 1 part of acrylic acid chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) was used in the same manner to obtain 33 parts of the target product.

[Monomer No. 3: 4-methacrylamido-1-hydroxybutane-1,1-diphosphonic acid dipotassium salt]
Monomer No. 40 parts of the target product were obtained in the same manner except that 24 parts of potassium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 17.1 parts of sodium hydroxide in the synthesis of 1.

[Monomer No. 4: 4-acrylamido-1-hydroxybutane-1,1-diphosphonic acid dipotassium salt]
Monomer No. 40 parts of the desired product were obtained in the same manner except that 24 parts of potassium hydroxide was used instead of 17.1 parts of sodium hydroxide in the synthesis of 2.

[Monomer No. 5: 4-Methacrylamide-1-hydroxybutane-1,1-diphosphonic acid di (triethylammonium) salt]
Monomer No. In the same manner as Example 1, except that 43.3 parts of triethylamine (manufactured by Kanto Chemical Co., Inc.) was used instead of 17.1 parts of sodium hydroxide, 44 parts of the target product was obtained.

[Monomer No. 6: 4-acrylamido-1-hydroxybutane-1,1-diphosphonic acid di (triethylammonium) salt]
Monomer No. In the synthesis of 2, 44 parts of the target product was obtained in the same manner except that 43.3 parts of triethylamine was used instead of 17.1 parts of sodium hydroxide.

<Synthesis of polymer (copolymer)>
[Polymer Synthesis Example 1: Synthesis of copolymer polymer 1 containing phosphonic acid group salt]
In a reaction vessel equipped with a gas introduction tube, a thermometer, and a reflux condenser, 180 parts of N, N-dimethylformamide (DMF, manufactured by Kanto Chemical Co., Inc.) was placed in an argon atmosphere and heated to 75 ° C.
Thereto, 12 parts of monomer No. 1 part 211 aqueous solution, diacetone acrylamide (DAAM, manufactured by Tokyo Chemical Industry Co., Ltd.) 48 parts DMF solution 222 parts, and 2,2′-azobisisobutyronitrile (AIBN, manufactured by Tokyo Chemical Industry Co., Ltd.) 7.2 parts 188 parts of DMF solution was added in 12 portions each 30 minutes. Stirring was further continued at 75 ° C. for 4 hours after all the addition was completed, and then the polymerization was stopped by cooling.
The reaction solution was poured into a mixed solvent of 250 parts of hexane and 150 parts of tetrahydrofuran while stirring, and then left to separate and extract the resin solution layer. Further, the resin solution was washed twice with a hexane / tetrahydrofuran mixed solvent, the solvent was distilled off, and the residue was vacuum dried at 70 ° C. to obtain 64 parts of resin.
When 1 part of this resin was dissolved in 120 parts of ion-exchanged water and titrated with 0.1N KOH methanol solution using thymolphthalein as an indicator, the acid value was determined to be 32 mgKOH / g. Monomer No. It agreed well with the value of 32 mg KOH / g calculated from the acid value of 1 as copolymerized according to the charge ratio.
Based on this acid value, a 10% by mass resin aqueous solution was prepared while neutralizing with sodium hydroxide. When the viscosity of this solution was measured at 25 ° C., it was 2.39 mPa · sec.
The 10% by mass resin aqueous solution thus obtained was used for preparing a pigment dispersion.
From the titration result of the monomer raw material alendronic acid, it can be seen that three of the four OH groups of the phosphonic acid are neutralized when the color of thymolphthalein is discolored. Of the four OH groups, three are neutralized with sodium ions.

[Polymer Synthesis Example 2: Synthesis of Polymer 2]
In the synthesis of polymer 1, monomer no. Polymer 2 was synthesized in the same manner except that the charge of 1 was changed to 18 parts by mass and the charge of DAAM was changed to 42 parts by mass.
The acid value of the polymer 2 was 47 (mgKOH / g). The polymer 2 was neutralized in the same manner as in the case of the polymer 1 and used for preparing a pigment dispersion.

[Polymer Synthesis Example 3: Synthesis of Polymer 3]
In the synthesis of polymer 1, monomer no. Polymer 3 was synthesized in the same manner except that the charge of 1 was changed to 24 parts by mass and the charge of DAAM was changed to 36 parts by mass.
The acid value of the polymer 3 was 62 (mgKOH / g). The polymer 3 was neutralized in the same manner as in the case of the polymer 1 and used for preparing a pigment dispersion.

[Polymer Synthesis Example 4: Synthesis of Polymer 4]
In the synthesis of polymer 1, monomer no. Polymer 4 was synthesized in the same manner except that the charge of 1 was changed to 30 parts by mass and the charge of DAAM was changed to 30 parts by mass.
The acid value of the polymer 4 was 78 (mgKOH / g). The polymer 4 was neutralized in the same manner as in the case of the polymer 1 and used for preparing a pigment dispersion.

[Polymer Synthesis Example 5: Synthesis of Polymer 5]
In the synthesis of polymer 1, monomer no. Polymer 5 was synthesized in the same manner except that the charge of 1 was changed to 36 parts by mass and the charge of DAAM was changed to 24 parts by mass.
The acid value of the polymer 5 was 93 (mgKOH / g). The polymer 5 was neutralized in the same manner as in the case of the polymer 1 and used for preparing a pigment dispersion.

[Polymer Synthesis Example 6: Synthesis of Polymer 6]
In the synthesis of polymer 1, monomer no. Polymer 6 was synthesized in the same manner except that the charge of 1 was changed to 42 parts by mass and the charge of DAAM was changed to 18 parts by mass.
The acid value of the polymer 6 was 109 (mgKOH / g). The polymer 6 was neutralized in the same manner as in the case of the polymer 1 and used for preparing a pigment dispersion.

[Polymer Synthesis Example 7: Synthesis of Polymer 7]
In the synthesis of polymer 1, monomer no. Polymer 7 was synthesized in the same manner except that the charge of 1 was changed to 48 parts by mass and the charge of DAAM was changed to 12 parts by mass.
The acid value of the polymer 7 was 140 (mgKOH / g). This polymer 7 was neutralized in the same manner as in the case of polymer 1 and used for preparing a pigment dispersion.
Table 1 shows the viscosity measurement results of a 10% aqueous resin solution of each polymer.

[Polymer Synthesis Example 8: Synthesis of Polymer 8]
In the synthesis of polymer 1, monomer no. 1 is a monomer no. Polymer 8 was synthesized in the same manner except that it was changed to 2. Polymer 8 was neutralized in the same manner and used for preparing a pigment dispersion.

[Polymer Synthesis Example 9: Synthesis of Polymer 9]
In the synthesis of polymer 2, monomer no. 1 is a monomer no. Polymer 9 was synthesized in the same manner except that it was changed to 2. Polymer 9 was neutralized in the same manner and used for preparing a pigment dispersion.

[Polymer Synthesis Example 10: Synthesis of Polymer 10]
In the synthesis of polymer 3, monomer no. 1 is a monomer no. Polymer 10 was synthesized in the same manner except that it was changed to 2. Polymer 10 was neutralized in the same manner and used for preparing a pigment dispersion.

[Polymer Synthesis Example 11: Synthesis of Polymer 11]
In the synthesis of polymer 4, monomer no. 1 is a monomer no. Polymer 11 was synthesized in the same manner except that it was changed to 2. Polymer 11 was neutralized in the same manner and used for preparing a pigment dispersion.

[Polymer Synthesis Example 12: Synthesis of Polymer 12]
In the synthesis of polymer 5, monomer no. 1 is a monomer no. Polymer 12 was synthesized in the same manner except that it was changed to 2. Polymer 12 was neutralized in the same manner and used for preparing a pigment dispersion.

[Polymer Synthesis Example 13: Synthesis of Polymer 13]
In the synthesis of polymer 6, monomer no. 1 is a monomer no. Polymer 13 was synthesized in the same manner except that it was changed to 2. Polymer 13 was used as it was without being neutralized.

[Polymer Synthesis Example 14: Synthesis of Polymer 14]
In the synthesis of polymer 7, monomer no. 1 is a monomer no. Polymer 14 was synthesized in the same manner except that it was changed to 2. The polymer 14 was used as it was without being neutralized.
The results for these polymers 8-14 are shown in Table 1.

[Polymer Synthesis Example 15: Synthesis of Polymer 15]
In the synthesis of polymer 3, polymer 15 was synthesized in the same manner except that DAAM was changed to diacetone methacrylamide (DAMAM, synthesized with reference to the synthesis method described in JP-A No. 10-7634), neutralized and pigmented Used for dispersion preparation.

[Polymer Synthesis Example 16: Synthesis of Polymer 16]
In the synthesis of polymer 4, polymer 16 was synthesized in the same manner except that DAAM was changed to diacetone methacrylamide (DAMAM, synthesized with reference to the synthesis method described in JP-A-10-7634), neutralized and pigmented Used for dispersion preparation.

[Polymer Synthesis Example 17: Synthesis of Polymer 17]
In the synthesis of polymer 5, polymer 17 was synthesized in the same manner except that DAAM was changed to diacetone methacrylamide (DAMAM, synthesized with reference to the synthesis method described in JP-A-10-7634), neutralized and pigmented Used for dispersion preparation.
The results for these polymers 15-17 are shown in Table 1.

[Polymer Synthesis Example 18: Synthesis of Polymer 18]
Polymer 18 was synthesized in the same manner except that DAAM was changed to diacetone methacrylamide (DAMAM) in the synthesis of polymer 9, and neutralized and used for the preparation of a pigment dispersion.

[Polymer Synthesis Example 19: Synthesis of Polymer 19]
Polymer 19 was synthesized in the same manner except that DAAM was changed to diacetone methacrylamide (DAMAM) in the synthesis of polymer 11, and the polymer 19 was neutralized and used for preparing a pigment dispersion.

[Polymer Synthesis Example 20: Synthesis of Polymer 20]
Polymer 20 was synthesized in the same manner except that DAAM was changed to diacetone methacrylamide (DAMAM) in the synthesis of polymer 12, and the polymer 20 was neutralized and used for preparing a pigment dispersion.
The results for these polymers 18-20 are shown in Table 1.

[Polymer Synthesis Example 21: Synthesis of Polymer 21]
In the synthesis of polymer 4, 3.6 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.) instead of 7.2 parts of AIBN and α-thio as a radical chain transfer agent Polymer 21 was synthesized in the same manner except that 4 parts of glycerol (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used, neutralized, and used for preparing a pigment dispersion.

[Polymer Synthesis Example 22: Synthesis of Polymer 22]
In the synthesis of polymer 4, polymer 22 was synthesized and neutralized in the same manner except that 1.8 parts of AIBN and 4 parts of 1-dodecanethiol (manufactured by Tokyo Chemical Industry Co., Ltd.) were used instead of 7.2 parts of AIBN. Used for preparation of pigment dispersion.

[Polymer Synthesis Example 23: Synthesis of Polymer 23]
In the synthesis of polymer 4, polymer 23 was synthesized in the same manner except that AIBN was replaced with 3.6 parts instead of 7.2 parts of AIBN, neutralized and used for preparation of a pigment dispersion.

[Polymer Synthesis Example 24: Synthesis of Polymer 24]
In the synthesis of polymer 4, polymer 24 was synthesized in the same manner except that 1.8 parts of AIBN was used instead of 7.2 parts of AIBN, and neutralized and used for preparing a pigment dispersion.

[Polymer Synthesis Example 25: Synthesis of Polymer 25]
In the synthesis of polymer 12, polymer 25 was synthesized in the same manner except that AIBN 8 parts was used instead of AIBN 7.2 parts and the reaction temperature at 75 ° C. was changed to 90 ° C., and neutralized to prepare a pigment dispersion. used.

[Polymer Synthesis Example 26: Synthesis of Polymer 26]
In the synthesis of polymer 12, polymer 26 was synthesized in the same manner except that AIBN was 5.4 parts instead of AIBN 7.2 parts, and neutralized and used for preparing a pigment dispersion.

[Polymer Synthesis Example 27: Synthesis of Polymer 27]
In the synthesis of polymer 12, polymer 27 was synthesized in the same manner except that AIBN was replaced with 3.6 parts instead of 7.2 parts of AIBN, neutralized and used for preparation of a pigment dispersion.

[Polymer Synthesis Example 28: Synthesis of Polymer 28]
In the synthesis of polymer 12, polymer 28 was synthesized in the same manner except that AIBN was changed to 1.8 parts instead of AIBN 7.2 parts and the reaction temperature was 75 ° C. to 70 ° C. used.

[Polymer Synthesis Example 29: Synthesis of Polymer 29]
In the synthesis of polymer 4, monomer no. 1 is a monomer no. Polymer 29 was polymerized in the same manner except that it was changed to 3, and polymer 29 was prepared in the same manner except that neutralization with sodium hydroxide was changed to neutralization with potassium hydroxide, and used for the preparation of a pigment dispersion.

[Polymer Synthesis Example 30: Synthesis of Polymer 30]
In the synthesis of polymer 3, monomer no. 1 is a monomer no. Polymer 30 was polymerized in the same manner except that it was replaced with 4, and polymer 30 was prepared in the same manner except that neutralization with sodium hydroxide was changed to neutralization with potassium hydroxide, and was used for preparing a pigment dispersion.

[Polymer Synthesis Example 31: Synthesis of Polymer 31]
In the synthesis of polymer 29, monomer no. 30 parts of DAAM 3 and 30 parts of DAAM. 3 was replaced with 36 parts and DAMAM 24 parts, and the polymer 31 was synthesized in the same manner, neutralized, and used to prepare a pigment dispersion.

[Polymer Synthesis Example 32: Synthesis of Polymer 32]
In the synthesis of polymer 3, monomer no. 1 is a monomer no. Polymer 32 was polymerized in the same manner except that 5 was replaced, and polymer 32 was prepared in the same manner except that neutralization with sodium hydroxide was changed to neutralization with triethylamine, and used for the preparation of a pigment dispersion.

[Polymer Synthesis Example 33: Synthesis of Polymer 33]
In the synthesis of polymer 32, monomer no. 24 parts of DA5 and 36 parts of DAAM. Polymer 33 was prepared in the same manner except that it was changed to 36 parts of 5 and 24 parts of DAAM, and used for the preparation of a pigment dispersion.

[Polymer Synthesis Example 34: Synthesis of Polymer 34]
In the synthesis of polymer 33, monomer no. 5 is a monomer no. A polymer 34 was prepared in the same manner except that it was replaced with 6, and used for preparing a pigment dispersion.

[Polymer Synthesis Example 35: Synthesis of Polymer 35]
In the synthesis of polymer 18, monomer no. 2 is a monomer no. Polymer 35 was prepared in the same manner except that the polymerization was carried out in place of 6 and no neutralization treatment was performed, and this was used for the preparation of a pigment dispersion.

[Comparative Polymer Synthesis Example 1: Synthesis of Polymer 36 (Comparative 1)]
In the synthesis of polymer 1, DAAM was not used and monomer no. Polymer 36 was synthesized in the same manner except that 60 parts of 1 was used, and used for preparing a pigment dispersion without neutralization.

[Comparative Polymer Synthesis Example 2: Synthesis of Polymer 37 (Comparative 2)]
In the synthesis of polymer 2, monomer no. 1 is a monomer no. Polymer 37 was synthesized in the same manner except that DAAM was changed to 2-hydroxypropylacrylamide in place of 3, and used for preparing a pigment dispersion without neutralization.
The results are shown in Table 1.

(In the table, 3Na, 1H, etc., M + represents 3 Na ions and 1 proton. Similarly, 2K and 2H represent 2 K ions and 2 protons. TEtA represents triethylamine with a hydrogen atom. (Organic ammonium ion attached.)

<Preparation of pigment dispersion>
[Pigment dispersion preparation example 1]
After premixing the following mixture, it was circulated and dispersed for 10 minutes at a peripheral speed of 10 m / s with a disk-type bead mill (Shinmaru Enterprises Co., Ltd., KDL type, media: using zirconia balls with a diameter of 0.1 mm), and the pore size was 1 A pigment dispersion 1 was obtained by filtration through a 2 μm membrane filter.
・ Carbon black (NIPEX150, manufactured by Degussa) ・ ・ ・ ・ ・ ・ 20.0 mass parts ・ Naphthalenesulfonic acid Na formalin condensate ・ ・ ・ ・ ・ ・ 13.0 mass parts (Pionin A- 45-PN Takemoto Yushi Co., Ltd., solid content 10 mass%)
・ Pure water ... 67.0 parts by mass

[Pigment dispersion preparation example 2]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 2 was prepared according to the formulation shown in Table 2.
The viscosity at 25 ° C. of a 10 wt% aqueous solution of 1-hydroxyethylidene-1,1-diphosphonic acid (manufactured by STREM) was 2 mPa · s.

[Pigment Dispersion Preparation Example 3]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 3 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 4]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 4 was prepared according to the formulation shown in Table 2.

[Pigment dispersion preparation example 5]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 5 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 6]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 6 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 7]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 7 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 8]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 8 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 9]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 9 was prepared according to the formulation shown in Table 2.

[Pigment dispersion preparation example 10]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 10 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 11]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 11 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 12]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 12 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 13]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 13 was prepared according to the formulation shown in Table 2.

[Pigment dispersion preparation example 14]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 14 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 15]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 15 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 16]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 16 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 17]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 17 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 18]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 18 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 19]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 19 was prepared according to the formulation shown in Table 2.

[Pigment dispersion preparation example 20]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 20 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 21]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 21 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 22]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 22 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 23]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 23 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 24]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 24 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 25]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 25 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 26]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 26 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 27]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 27 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 28]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 28 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 29]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 29 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 30]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 30 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 31]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 31 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 32]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 32 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 33]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 33 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 34]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 34 was prepared according to the formulation shown in Table 2.

[Pigment dispersion preparation example 35]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 35 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 37]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 37 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 38]
In the same manner as in Pigment Dispersion Preparation Example 1, pigment dispersion 38 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 39]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 39 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 40]
In the same manner as in Pigment Dispersion Preparation Example 1, Pigment Dispersion 40 was prepared according to the formulation shown in Table 2.

[Pigment Dispersion Preparation Example 41]
In the same manner as in Pigment dispersion preparation example 1, pigment dispersion 41 was prepared according to the formulation shown in Table 2.

<Preparation of ink for ink jet recording>
[Example 1]
The following materials were mixed, stirred for 1.5 hours, and filtered through a membrane filter having a pore size of 1.2 μm to obtain an ink.
・ Pigment Dispersion 1 (Pigment solid content 20% by mass) ... 40.0 parts by mass 1,3-butanediol ... ... 20.0 parts by mass (reagents manufactured by Tokyo Chemical Industry Co., Ltd., water-soluble organic solvents)
・ Glycerin ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 10.0 parts by mass (Kanto Chemicals reagent, water-soluble organic solvent)
・ 2-Ethyl-1,3-hexanediol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 1.0 parts by mass (reagent manufactured by Tokyo Chemical Industry Co., Ltd., water-soluble organic solvent)
・ 2,2,4-trimethyl-1,3-pentanediol: 1.0 part by mass (reagent manufactured by Tokyo Chemical Industry Co., Ltd., water-soluble organic solvent)
-Fluorosurfactant ... 2.0 parts by mass (solid content 40% by mass, manufactured by DuPont, Zonyl FS-300)
-Copolymer polymer 4 aqueous solution containing bisphosphonic acid groups ... 20.0 parts by mass (solid content 10% by mass)
・ Distilled water ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 6.0 parts by mass

[Example 2]
The ink of Example 2 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 3]
The ink of Example 3 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 4]
The ink of Example 4 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 5]
The ink of Example 5 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 6]
The ink of Example 6 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 7]
The ink of Example 7 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 8]
Ink of Example 8 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 9]
Ink of Example 9 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 10]
The ink of Example 10 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 11]
The ink of Example 11 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 12]
The ink of Example 12 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 13]
Ink of Example 13 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 14]
The ink of Example 14 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 15]
The ink of Example 15 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 16]
The ink of Example 16 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 17]
Ink of Example 17 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 18]
Ink of Example 18 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 19]
The ink of Example 19 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 20]
The ink of Example 20 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 21]
The ink of Example 21 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 22]
Ink of Example 22 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 23]
The ink of Example 23 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 24]
The ink of Example 24 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 25]
The ink of Example 25 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 26]
Ink of Example 26 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 27]
Ink of Example 27 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 28]
The ink of Example 28 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 29]
Ink of Example 29 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 30]
The ink of Example 30 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 31]
The ink of Example 31 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 32]
The ink of Example 32 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 33]
The ink of Example 33 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 34]
The ink of Example 34 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 35]
The ink of Example 35 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 36]
Ink of Example 36 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 37]
The ink of Example 37 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 38]
The ink of Example 38 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Example 39]
Ink of Example 39 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Comparative Example 1]
The ink of Comparative Example 1 was prepared according to the formulation shown in Table 3 in the same manner as in Example 1.

[Comparative Example 2]
The ink of Comparative Example 2 was prepared according to the formulation shown in Table 3 by the same operation as in Example 1.

[Comparative Example 3]
The ink of Comparative Example 3 was prepared according to the formulation shown in Table 3 by the same operation as in Example 1.

[Evaluation results]
Next, the inkjet inks of Examples 1 to 39 and Comparative Examples 1 to 3 were evaluated by the following evaluation method. The results are shown in Table 4 below.

<Image density>
64 point character JIS X 0208 (1997), 2223, which was prepared by using Microsoft Word 2000 (manufactured by Microsoft) by filling ink prepared in an ink jet printer (manufactured by Ricoh Co., Ltd., IPSiO GX5000) under an environment of 23 ° C. and 50% RH. Are printed on plain paper 1 (XEROX 4200, manufactured by XEROX) and plain paper 2 (MyPaper, manufactured by Ricoh Co., Ltd.). The color of the part was measured with X-Rite 938 (manufactured by X-Rite Co., Ltd.) and judged according to the following evaluation criteria.
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〕
(black)
A: 1.25 or more.
B: 1.20 or more and less than 1.25.
C: 1.10 or more and less than 1.20.
D: Less than 1.10.
E: The pigment is gelled and cannot be dispersed in the ink and cannot be printed.
(yellow)
A: 0.80 or more.
B: 0.75 or more and less than 0.80.
C: 0.70 or more and less than 0.75.
D: Less than 0.70.
E: The pigment is gelled and cannot be dispersed in the ink and cannot be printed.
(Magenta)
A: 0.95 or more.
B: 0.85 or more and less than 0.95.
C: 0.75 or more and less than 0.85.
D: Less than 0.75.
E: The pigment is gelled and cannot be dispersed in the ink and cannot be printed.
(cyan)
A: 1.05 or more.
B: 0.95 or more and less than 1.05.
C: 0.85 or more and less than 0.95.
D: Less than 0.85.
E: The pigment is gelled and cannot be dispersed in the ink and cannot be printed.

<Storage stability of pigment dispersion>
Each pigment dispersion was put in a polyethylene container, sealed, stored at 60 ° C. for 1 week, the change rate of the viscosity after storage with respect to the viscosity before storage was determined from the following formula, and evaluated according to the following criteria.
Viscosity change rate (%) = (viscosity of pigment dispersion after storage / viscosity of pigment dispersion before storage) × 100

The viscosity was measured using a viscometer (RE500L, manufactured by Toki Sangyo Co., Ltd.), adjusted to 50 or 100 rotations according to the viscosity of the sample, and evaluated based on the following criteria. .
[Evaluation criteria]
A: Viscosity change rate is within ± 5%.
B: Viscosity change rate exceeds ± 5% and within ± 8%.
C: Viscosity change rate exceeds ± 8% and within ± 10%.
D: Viscosity change rate exceeds ± 10% and within ± 30%.
E: Viscosity change rate exceeds ± 30% (cannot be evaluated due to gelation).

<Ink storage stability>
Each ink was filled in an ink cartridge and stored at 60 ° C. for 1 week. The change rate of the viscosity after storage with respect to the viscosity before storage was obtained from the following formula and evaluated according to the following criteria.
Viscosity change rate (%) = (ink viscosity after storage / ink viscosity before storage) × 100
The viscosity was measured using a viscometer (RE80L, manufactured by Toki Sangyo Co., Ltd.), adjusted to 50 or 100 rotations according to the viscosity of the sample, and evaluated based on the following criteria. .
[Evaluation criteria]
A: Viscosity change rate is within ± 5%.
B: Viscosity change rate exceeds ± 5% and within ± 8%.
C: Viscosity change rate exceeds ± 8% and within ± 10%.
D: Viscosity change rate exceeds ± 10% and within ± 30%.
E: Viscosity change rate exceeds ± 30% (cannot be evaluated due to gelation).

  From the results shown in Table 4, the ink of the example can obtain a higher image density even on general plain paper than the ink of the comparative example, and the ink can be used even if the content of the water-soluble organic solvent exceeds 20% by mass. It was found that the storage stability of was excellent.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Paper feed tray 3 Paper discharge tray 4 Front surface 5 Upper surface 6 Cartridge loading part 7 Operation part 8 Front cover 10 Ink cartridge 21 Frame 21A Side plate 21B Side plate 21C Rear plate 22 Flexible cable 23 Supply pump unit 25 Main body side holder 26 Fixed Rib 31 Guide rod 32 Stay 33 Carriage 34 Recording head 35 Sub tank 36 Ink supply tube 37 Ink supply tube 41 Paper stacking portion (bottom plate)
42 paper 43 half moon roller (paper roller)
44 Separating Pad 45 Guide 51 Conveying Belt 52 Counter Roller 53 Conveying Guide 54 Pressing Member 55 Tip Pressure Roller 56 Charging Roller 57 Conveying Roller 58 Tension Roller 61 Guide Member 71 Separating Claw 72 Paper Discharge Roller 73 Paper Discharge Roller 81 Double-sided Paper Feed Unit 82 Manual Feeding Section 91 Subsystem 92 Cap 92a Cap 92b Cap 92c Cap 92d Cap 93 Wiper Blade 94 Empty Discharge Receiver 95 Wiper Cleaner 96 Cleaner Roll 98 Empty Discharge Receiver 99 Opening 111 Maintenance Device Frame 112A Cap Holder 112B Cap Holder 115 Carriage Lock 117 Carriage lock arm 118 Wiper liner 119 Flexible tube 120 Tubing pump (suction pump)
120a pump shaft 121 cam shaft 122A cap cam 122B cap cam 124 wiper cam 125 carriage lock cam 126 roller 128 cleaner cam 131 motor 131a motor shaft 132 motor gear 133 pump gear 134 intermediate gear 135 intermediate gear 136 intermediate gear 137 clutch gear 138 intermediate gear 140 139 Cam gear 141 Intermediate shaft 142 Home position sensor cam 150a Guide pin 150b Guide shaft 151 Holder 152 Spring 153 Slider 154 Guide pin 155 Guide pin 156 Guide groove 157 Cam pin

Special table 2009-513802 JP 2012-51357 A JP 2004-123904 A

Claims (9)

An ink for ink jet recording having a copolymer containing at least water, a water-soluble solvent, a pigment, and a salt of a diphosphonic acid group, wherein the copolymer containing the salt of the diphosphonic acid group is represented by the general formula (1). And an ink for inkjet recording, comprising at least a structural unit represented by the general formula (2).

(R ₁ in the general formula (1) represents a hydrogen atom or a methyl group, X represents an alkylene group having 1 to 3 carbon atoms, and M + represents an alkali metal ion, an organic ammonium ion, or a proton. Metals and protons and organic ammonium ions and protons may be mixed, and more than half of M + in the copolymer is alkali metal ions or organic ammonium ions.)

(R ₁ in the general formula (2) represents a hydrogen atom or a methyl group.)   2. The ink for ink jet recording according to claim 1, wherein the content of the structural unit of the general formula (1) in the copolymer containing a salt of the diphosphonic acid group is 30% by mass to 70% by mass.   The ink for inkjet recording according to claim 2, wherein the content of the structural unit of the general formula (1) in the copolymer containing a salt of the diphosphonic acid group is 40% by mass to 60% by mass.   4. The ink jet recording according to claim 1, wherein the copolymer containing a salt of the diphosphonic acid group has an aqueous solution viscosity (concentration of 10 mass%, 25 ° C.) of 2 to 4 mPa · s. ink. In an inkjet recording ink having a copolymer containing at least water, a water-soluble solvent, a pigment, and a salt of a diphosphonic acid group, the copolymer containing the salt of the diphosphonic acid group is a monomer represented by the general formula (3) An ink for ink-jet recording, which is synthesized by radical polymerization using at least a monomer represented by the general formula (4) as a starting material.

(R ₁ in the general formula (3) represents a hydrogen atom or a methyl group, X represents an alkylene group having 1 to 3 carbon atoms, and M + represents an alkali metal ion, an organic ammonium ion, or a proton.)

(R ₁ in the general formula (4) represents a hydrogen atom or a methyl group.)   An ink cartridge comprising the ink-jet recording ink according to claim 1 contained in a container.   An ink jet recording method comprising at least an ink flying step of recording an image by applying a stimulus to the ink for ink jet recording according to claim 1 and causing the ink for ink jet recording to fly.   6. An ink jet recording apparatus comprising at least ink flying means for recording an image by applying a stimulus to the ink for ink jet recording according to claim 1 and causing the ink for ink jet recording to fly.   An ink recorded matter comprising an image recorded with the ink for ink jet recording according to any one of claims 1 to 5 on a recording medium.

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