JP2012012500A - Water-based ink containing azo pigment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based ink which can improve the glossiness of printed products.SOLUTION: The water-based ink includes a coloring agent comprising the following A and B, and the following C, wherein the content of the C is ≥0.05 to ≤0.25 mass%. A is an azo pigment having a specific structure, B is a vinylic polymer containing hydrophobic structure units (a) having a specific structure, and hydrophilic structure units (b), C is a compound represented by the formula (wherein, R is either the following (1) or (2); (1) is a non-substituted, or hydroxyl, amino, nitro or carboxyl-substituted alkyl; (2) is a non-substituted, or amino, alkyl or hydroxyl-substituted phenyl).

Description

  The present invention relates to a water-based ink capable of improving the glossiness of a printed matter.

Various media have been used as inkjet recording media, and high-quality image quality is required not only for inkjet dedicated paper but also for printing media such as commercially available plain paper, high-quality paper, coated paper, and art paper. . A pigment is preferable as an ink coloring material that gives fastness such as water resistance and light resistance to plain paper and printing media, and various studies have been made on water-based pigment ink including the viewpoint of cost. Among them, azo pigments are preferably used as yellow pigments for inkjet recording.
However, it has been found that density unevenness and streak unevenness occur in ink that has been aged for a long time or at a high temperature.
As an aqueous ink for inkjet recording, C.I. I. An aqueous dispersion for inkjet recording having an aqueous pigment dispersion containing CI Pigment Yellow 74 and an anionic group-containing organic polymer compound is disclosed (for example, see Patent Document 1). Specifically, C.I. I. By using Pigment Yellow 74, and a copolymer of n-butyl methacrylate, n-butyl acrylate, 2-hydroxyethyl methacrylate, methacrylic acid and styrene as a dispersant, dispersibility, dispersion stability and clearness It is supposed that an image can be formed.

  However, the water-based ink for ink-jet recording constituted by using the pigment aqueous dispersion described in Patent Document 1 is deteriorated in discharge accuracy and used in density unevenness and streak unevenness when used after being stored for a long period of time or after aging at a high temperature. It was found that the level was not satisfactory.

  In addition, colored particles using a vinyl polymer having a specific structure are used for an azo pigment having a heterocycle substituted with a carbonyl group capable of forming an intramolecular hydrogen bond on a carbon atom adjacent to the carbon atom bonded to the azo group. Disclosed is an aqueous ink for inkjet recording that is excellent in ejection accuracy and can suppress the occurrence of uneven density and streaks even after storage for a long period of time or after being exposed to high temperatures. . (For example, refer to Patent Document 2).

  Patent Documents 3 and 4 describe that an organic monophosphonic acid is contained as a compound capable of preventing the occurrence of kogation against the heat of a recording liquid such as an aqueous ink for inkjet recording.

JP 2000-239594 A JP 2010-77400 A JP 2006-117773 A Japanese Patent No. 3896921

However, the water-based ink for inkjet recording described in Patent Document 2 has room for improvement in gloss. In addition, the water-based ink for ink-jet recording using a pigment does not have a sufficient glossiness of the printed matter compared to the ink using a dye, and the water-based ink for ink-jet recording using a pigment is about the same as that using a dye. There has been a demand for a printed product with high glossiness.
An object of the present invention is to provide a water-based ink capable of improving the glossiness of a printed matter.

  As a result of the study, the inventors of the present invention have found that the azo pigment having a heterocyclic ring substituted with a carbonyl group capable of forming an intramolecular hydrogen bond on a carbon atom adjacent to the carbon atom bonded to the azo group has a specific structure. It has been found that a water-based ink capable of improving the glossiness of a printed matter can be obtained by using a vinyl polymer having a colored particle and a specific organic monophosphonic acid compound.

That is, the object of the present invention is achieved by the following means.
[1]
A water-based ink containing a colorant containing the following A and B and the following C, wherein the content of C is 0.05% by mass or more and 0.25% by mass or less.
A: An azo pigment represented by the following general formula (1), a tautomer thereof, a salt or a hydrate thereof B: a hydrophobic structural unit (a) represented by the following general formula (PI) And a vinyl polymer containing a hydrophilic structural unit (b) C: a compound represented by the following general formula (2).

（一般式（Ｐ−Ｉ）中、Ｒ_１は水素原子、メチル基、又はハロゲン原子を表し、Ｌ_１は−ＣＯＯ−、−ＯＣＯ−、−ＣＯＮＲ_２−、−Ｏ−、又は置換若しくは無置換のフェニレン基を表し、Ｒ_２は水素原子、アルキル基を表す。Ｌ_２は単結合又は、２価の連結基を表す。Ａｒ_１は芳香環から誘導される１価の基を表す。） (In General Formula (1), Z represents a 5-6 membered heterocyclic ring, Y < ₁ >, Y < ₂ >, R < ₁₁ >, R < ₁₂ > represents a hydrogen atom or a substituent each independently, G < ₁ >, G < ₂ > is Each independently represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group or an aryl group. )

(In General Formula (PI), R ₁ represents a hydrogen atom, a methyl group, or a halogen atom, and L ₁ represents —COO—, —OCO—, —CONR ₂ —, —O—, or substituted or unsubstituted. R ₂ represents a hydrogen atom or an alkyl group, L ₂ represents a single bond or a divalent linking group, and Ar ₁ represents a monovalent group derived from an aromatic ring.)

(In general formula (2), R represents the following 1) or 2).
1) unsubstituted or alkyl group substituted by hydroxyl group, amino group, nitro group or carboxyl group,
2) A phenyl group which is unsubstituted or substituted with an amino group, an alkyl group or a hydroxyl group. )
[2]
In the general formula (2), R is a substituted or unsubstituted alkyl group substituted with a carboxyl group or a phenyl group, The water-based ink according to [1].
[3]
The water-based ink according to [1] or [2], wherein the vinyl polymer further contains a hydrophobic structural unit (a2) derived from an alkyl ester of acrylic acid or methacrylic acid.
[4]
At least one selected from the structural unit derived from phenoxyethyl (meth) acrylate and the structural unit derived from benzyl (meth) acrylate as the hydrophobic structural unit (a) is 20 masses in total with respect to the total mass of the vinyl polymer. %, And the hydrophilic structural unit (b) contains at least one selected from structural units derived from acrylic acid and methacrylic acid in a total amount of 30% by mass or less based on the total mass of the vinyl polymer. The water-based ink according to any one of [1] to [3].
[5]
Any of [1] to [4], wherein the hydrophobic structural unit (a) contains a total of 20 mass% of structural units derived from phenoxyethyl (meth) acrylate with respect to the total mass of the vinyl polymer. The water-based ink according to claim 1.
[6]
In General Formula (1), W ₁ and W ₂ are each independently an alkoxy group having 1 to 3 carbon atoms, an amino group, or an alkylamino group having 1 to 3 carbon atoms [1 ] The aqueous ink of any one of [5].
[7]
In the general formula (1), G ₁ and G ₂ are each independently an alkyl group having 1 to 3 carbon atoms, and the water-based ink according to any one of [1] to [6] .
[8]
In the general formula (1), Z is a 6-membered nitrogen-containing heterocycle, The water-based ink according to any one of [1] to [7],
[9]
The aqueous ink according to any one of [1] to [8], wherein the azo pigment represented by the general formula (1) is represented by the following general formula (10).

（一般式（１１）中、Ｚは６員含窒素ヘテロ環を表す。）
〔１１〕
前記アゾ顔料が、ソルトミリングによって後処理された顔料であることを特徴とする〔１〕〜〔１０〕のいずれか１項に記載の水系インク。
〔１２〕
更に、アセチレン系界面活性剤を含有することを特徴とする〔１〕〜〔１１〕のいずれか１項に記載の水系インク。 (In General Formula (10), Z represents a 5- or 6-membered nitrogen-containing heterocycle, and W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group, or an aryl group.)
[10]
The water-based ink as described in [9], wherein the azo pigment represented by the general formula (10) is represented by the following general formula (11).

(In general formula (11), Z represents a 6-membered nitrogen-containing heterocycle.)
[11]
The water-based ink according to any one of [1] to [10], wherein the azo pigment is a pigment after-treated by salt milling.
[12]
The water-based ink according to any one of [1] to [11], further comprising an acetylene-based surfactant.

  According to the present invention, it is possible to provide a water-based ink that can improve the glossiness of a printed matter before and after the passage of time.

Hereinafter, the present invention will be described in detail.
The water-based ink of the present invention contains a colorant containing the following A and B and the following C, and the content of C is 0.05% by mass or more and 0.25% by mass or less.
A: An azo pigment represented by the following general formula (1), a tautomer thereof, a salt or a hydrate thereof B: a hydrophobic structural unit (a) represented by the following general formula (PI) And a vinyl polymer containing a hydrophilic structural unit (b) C: a compound represented by the following general formula (2)

(In General Formula (1), Z represents a 5-6 membered heterocyclic ring, Y < ₁ >, Y < ₂ >, R < ₁₁ >, R < ₁₂ > represents a hydrogen atom or a substituent each independently, G < ₁ >, G < ₂ > is Each independently represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group or an aryl group. )

(In General Formula (PI), R ₁ represents a hydrogen atom, a methyl group, or a halogen atom, and L ₁ represents —COO—, —OCO—, —CONR ₂ —, —O—, or substituted or unsubstituted. R ₂ represents a hydrogen atom or an alkyl group, L ₂ represents a single bond or a divalent linking group, and Ar ₁ represents a monovalent group derived from an aromatic ring.)

(In general formula (2), R represents the following 1) or 2).
1) unsubstituted or alkyl group substituted by hydroxyl group, amino group, nitro group or carboxyl group,
2) A phenyl group which is unsubstituted or substituted with an amino group, an alkyl group or a hydroxyl group. )

  According to the above configuration, although it is not clear, by containing organic monophosphonic acid, drying shrinkage of the ink film on paper is suppressed, and diffuse reflection of light can be suppressed on the surface of the ink film, thereby improving the glossiness of the printed matter. be able to.

<Azo pigment>
The azo pigment used in the present invention is represented by the general formula (1).
First, the azo pigment represented by the following general formula (1) will be described.
The compound represented by the general formula (1) easily forms an intramolecular / intermolecular interaction of a dye molecule due to its specific structure, has a low solubility in water or an organic solvent, and has a preferable form of an azo pigment can do. Moreover, the average primary particle diameter becomes like this. Preferably it is 10-70 nm, More preferably, it is 25-60 nm.
A pigment is used by being finely dispersed as particles such as a molecular aggregate in a medium, unlike a dye used by being dissolved in water or an organic solvent in a molecular dispersion state.

(In General Formula (1), Z represents a 5- to 6-membered nitrogen-containing heterocyclic ring, Y ₁ , Y ₂ , R ₁₁ , and R ₁₂ each independently represent a hydrogen atom or a substituent, and G ₁ , G ₂ Each independently represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group or an aryl group. To express.)

  Hereinafter, the azo pigment represented by the general formula (1), tautomers thereof, salts or hydrates thereof will be described in detail.

In the general formula (1), W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group, or an aryl group.
The alkoxy group represented by W ₁ or W ₂ is preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, and among them, a substituted or unsubstituted alkoxy group having 1 to 8 carbon atoms, among others. Further, a substituted or unsubstituted alkoxy group having 1 to 4 carbon atoms is preferable. For example, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, s- Examples include butoxy group, t-butoxy group, n-octyloxy group, 2-methoxyethoxy group and the like. Particularly preferred is a methoxy group.

Examples of the amino group represented by W ₁ and W ₂ include an alkylamino group, an arylamino group, and a heterocyclic amino group, preferably an amino group, a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, Examples thereof include substituted or unsubstituted anilino groups having 6 to 30 carbon atoms, including amino groups, substituted or unsubstituted alkylamino groups having 1 to 8 carbon atoms, and substituted or unsubstituted anilino groups having 6 to 18 carbon atoms. Further, an amino group, a substituted or unsubstituted alkylamino group having 1 to 4 carbon atoms, and a substituted or unsubstituted anilino group having 6 to 12 carbon atoms are preferable. For example, an amino group (—NH ₂ ), methylamino group (-NHCH _3), dimethylamino group _{{-N (CH 3) 2}} , an anilino group (-NHPh), N-methyl - anilino group {-N (CH ) Ph}, diphenylamino group {-N _{(Ph) 2},} and the like. Particularly preferred is an amino group.

Examples of the alkyl group represented by W ₁ and W ₂ include linear, branched, and cyclic substituted or unsubstituted alkyl groups, including cycloalkyl groups, bicycloalkyl groups, and tricyclo structures having many ring structures. To do. An alkyl group (for example, an alkyl group of an alkoxy group or an alkylthio group) in a substituent described below also represents such an alkyl group. Specifically, the alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s -Butyl group, t-butyl group, n-octyl group, eicosyl group, 2-chloroethyl group, 2-cyanoethyl group, 2-ethylhexyl group and the like are mentioned, and the cycloalkyl group preferably has 3 to 30 carbon atoms. Substituted or unsubstituted cycloalkyl groups such as cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc., and the bicycloalkyl group is preferably a substituted or unsubstituted group having 5 to 30 carbon atoms. Bicycloalkyl group, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms, for example, bicyclo 1,2,2] heptan-2-yl group, a bicyclo [2,2,2] octan-3-yl group.

The aryl group represented by W ₁ or W ₂ is preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and among them, a substituted or unsubstituted aryl group having 6 to 18 carbon atoms. Further, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms is preferable, and examples thereof include a phenyl group, a p-tolyl group, a naphthyl group, an m-chlorophenyl group, and an o-hexadecanoylaminophenyl group. .

Preferable W ₁ and W ₂ each independently include an alkoxy group, an amino group or an alkyl group, and among them, an alkoxy group or an amino group is preferable, and an alkoxy group having 1 to 5 carbon atoms in total or an amino group (—NH ₂ Group), an alkylamino group having 1 to 5 carbon atoms is more preferable, an alkoxy group having 1 to 3 carbon atoms or an alkylamino group having 1 to 3 carbon atoms is particularly preferable, and among them, a methoxy group is most preferable. When W is an alkoxy group having 1 to 5 carbon atoms, an amino group, or an alkylamino group having 1 to 5 carbon atoms, the dye molecule has strong interaction (hydrogen bonding or π-π stacking) within and between molecules. In terms of good hue and high fastness (light resistance, gas resistance, heat resistance, water resistance, chemical resistance), it becomes easier to form a more stable molecular structure (for example, a three-dimensional network). preferable.

In the general formula (1), R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent. When R ₁₁ and R ₁₂ represent a substituent, the substituent may be a straight chain having 1 to 12 carbon atoms or A branched alkyl group, a linear or branched aralkyl group having 7 to 18 carbon atoms, a linear or branched alkenyl group having 2 to 12 carbon atoms, a linear or branched alkynyl group having 2 to 12 carbon atoms, and 3 carbon atoms -12 linear or branched cycloalkyl group, C3-12 linear or branched cycloalkenyl group (for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec- Butyl, t-butyl, 2-ethylhexyl, 2-methylsulfonylethyl, 3-phenoxypropyl, trifluoromethyl, cyclopentyl), halogen atom (for example, chlorine atom, bromine atom), aryl A group (for example, phenyl, 4-t-butylphenyl, 2,4-di-t-amylphenyl), a heterocyclic group (for example, imidazolyl, pyrazolyl, triazolyl, 2-furyl, 2-thienyl, 2-pyrimidinyl, 2 -Benzothiazolyl), cyano group, hydroxyl group, nitro group, carboxy group, amino group, alkyloxy group (for example, methoxy, ethoxy, 2-methoxyethoxy, 2-methylsulfonylethoxy), aryloxy group (for example, phenoxy, 2 -Methylphenoxy, 4-t-butylphenoxy, 3-nitrophenoxy, 3-t-butyloxycarbonylphenoxy, 3-methoxycarbonylphenyloxy, acylamino groups (for example, acetamide, benzamide, 4- (3-t-butyl- 4-hydroxyphenoxy) butane ), Alkylamino groups (for example, methylamino, butylamino, diethylamino, methylbutylamino), arylamino groups (for example, phenylamino, 2-chloroanilino), ureido groups (for example, phenylureido, methylureido, N, N -Dibutylureido), sulfamoylamino group (for example, N, N-dipropylsulfamoylamino), alkylthio group (for example, methylthio, octylthio, 2-phenoxyethylthio), arylthio group (for example, phenylthio, 2-butoxy) -5-t-octylphenylthio, 2-carboxyphenylthio), alkyloxycarbonylamino groups (eg methoxycarbonylamino), alkylsulfonylamino groups and arylsulfonylamino groups (eg methylsulfonylamino) , Phenylsulfonylamino, p-toluenesulfonylamino), carbamoyl group (eg, N-ethylcarbamoyl, N, N-dibutylcarbamoyl), sulfamoyl group (eg, N-ethylsulfamoyl, N, N-dipropylsulfamoyl) , N-phenylsulfamoyl), sulfonyl group (eg, methylsulfonyl, octylsulfonyl, phenylsulfonyl, p-toluenesulfonyl), alkyloxycarbonyl group (eg, methoxycarbonyl, butyloxycarbonyl), heterocyclic oxy group (eg, 1-phenyltetrazol-5-oxy, 2-tetrahydropyranyloxy), azo group (eg, phenylazo, 4-methoxyphenylazo, 4-pivaloylaminophenylazo, 2-hydroxy-4-propanoylsulfate) Nylazo), acyloxy group (for example, acetoxy), carbamoyloxy group (for example, N-methylcarbamoyloxy, N-phenylcarbamoyloxy), silyloxy group (for example, trimethylsilyloxy, dibutylmethylsilyloxy), aryloxycarbonylamino group ( For example, phenoxycarbonylamino), imide group (for example, N-succinimide, N-phthalimide), heterocyclic thio group (for example, 2-benzothiazolylthio, 2,4-di-phenoxy-1,3,5-triazole) -6-thio, 2-pyridylthio), sulfinyl group (for example, 3-phenoxypropylsulfinyl), phosphonyl group (for example, phenoxyphosphonyl, octyloxyphosphonyl, phenylphosphonyl), aryloxycarbonyl group ( Eg to phenoxycarbonyl), an acyl group (e.g., acetyl, 3-phenylpropanoyl, benzoyl), ionic hydrophilic groups (e.g., carboxyl group, a sulfo group, a phosphono group and a quaternary ammonium group).

In the general formula (1), preferred R ₁₁ and R ₁₂ are each independently a substituted or unsubstituted acylamino group having 1 to 8 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted group. An unsubstituted aryl group having 6 to 18 carbon atoms, or a substituted or unsubstituted heterocyclic group having 4 to 12 carbon atoms, more preferably a linear or branched alkyl group having 1 to 8 carbon atoms in total. Group, a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, among which a linear alkyl group or branched alkyl group having 1 to 8 carbon atoms is preferable, and more specifically, a methyl group or an i-propyl group Or a t-butyl group is preferable, an i-propyl group or a t-butyl group is particularly preferable, and a t-butyl group is most preferable among them.
By making R ₁₁ and R _{12 a} straight chain alkyl group or a branched alkyl group having a small total carbon number (1 to 4 carbon atoms), the dye molecule arrangement can be sterically controlled (arranged at a certain distance and angle). Become. As a result, a structure having stable intramolecular / intermolecular interaction (hydrogen bond or π-π stacking) is easily formed, and a more stable molecular arrangement structure (for example, a three-dimensional network) can be easily formed. Therefore, it is preferable in terms of good hue, coloring power, and high image fastness (light resistance, gas resistance, heat resistance, water resistance, chemical resistance).

  In the general formula (1), Z represents a 5- or 6-membered heterocyclic group, which may be further condensed. Z is preferably a 5- or 6-membered substituted or unsubstituted heterocyclic group, more preferably a 6-membered nitrogen-containing heterocyclic group, and particularly preferably a 6-membered nitrogen-containing heterocycle having 3 to 10 carbon atoms. It is a cyclic group.

  Examples of the heterocyclic group represented by Z include pyridyl, pyrazinyl, pyridazinyl, pyrimidinyl, triazinyl, quinolinyl, isoquinolinyl, quinazolinyl, cinnolinyl, phthalazinyl, quinoxalinyl, pyrrolyl, indolyl, furyl. , Benzofuryl, thienyl, benzothienyl, pyrazolyl, imidazolyl, benzimidazolyl, triazolyl, oxazolyl, benzoxazolyl, thiazolyl, benzothiazolyl, isothiazolyl, benzisothiazolyl, thiadiazolyl, isoxazolyl, benzisoxazolyl, pyrrolidinyl, piperidinyl, piperidinyl Imidazolidinyl, thiazolinyl, sulfolanyl and the like.

  Examples of preferred heterocyclic groups are pyridyl, pyrimidinyl, S-triazinyl, pyridazinyl, pyrazinyl, 1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, imidazolyl, more preferably pyridyl, pyrimidinyl, S- Triazinyl, pyridazinyl, and pyrazinyl. Pyrimidinyl and S-triazinyl are particularly preferred from the viewpoint of hue, tinting strength, and image fastness. Furthermore, pyrimidinyl having a substituent at 4,6- and C1-C4 at the 2-position S-triazinyl having an alkoxy group is preferable from the viewpoint of hue and image fastness, and among them, pyrimidinyl having a substituent at 4,6- is most preferable from the viewpoint of improving the light fastness of a good image.

  By making Z a pyrimidinyl group or S-triazinyl group, the bis-type azo dye can easily form an intramolecular hydrogen bond with an amino group and a nitrogen-containing 6-membered heterocycle, and the dye molecule arrangement is controlled sterically (constant It is easy to arrange by distance, angle and flatness. As a result, a structure having stable intramolecular / intermolecular interaction (hydrogen bond or π-π stacking) is easily formed, and a more stable molecular arrangement structure (for example, a three-dimensional network) can be easily formed. Therefore, it is preferable in terms of good hue, coloring power, and high image fastness (light resistance, gas resistance, heat resistance, water resistance, chemical resistance).

G ₁ and G ₂ each independently represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and particularly preferably a hydrogen atom, a methyl group, an ethyl group, or n- Propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, cyclopropyl group, benzyl group, 2-phenethyl group, vinyl group, allyl group, ethynyl group, propargyl Group, phenyl group, p-tolyl group, naphthyl group, pyridyl group, pyrimidinyl group and pyrazinyl group are preferable, and hydrogen atom, methyl group, phenyl group, pyridyl group, pyrimidinyl group and pyrazinyl group are preferable. 1-8 linear or branched alkyl groups, 2-pyridyl groups, 2,6-pyrimidinyl groups, 2,5-pyrazinyl groups are preferred. Ku, alkyl group having a total carbon number of 1-3 is more preferred. Further, from the viewpoint of hue and image fastness, a hydrogen atom and a methyl group are preferable, and among them, a methyl group is particularly preferable from the viewpoint of improving the hue and light fastness.

Examples of the substituent when Y ₁ and Y ₂ represent a substituent include a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a cyano group, a hydroxyl group, a nitro group, Alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryl Oxycarbonylamino group, sulfamoylamino group, alkyl or arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, alkyl or arylsulfinyl group, alkyl or arylsulfo Examples include an alkyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an aryl or heterocyclic azo group, an imide group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, and a silyl group. As mentioned. Particularly preferable examples of Y include a hydrogen atom, an alkyl group (for example, a methyl group), an aryl group (for example, a phenyl group), a heterocyclic group (for example, a 2-pyridyl group), and an alkylthio group (for example, a methylthio group). Furthermore, they are a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a phenyl group, and a methylthio group. Further, from the viewpoint of hue and image fastness, a hydrogen atom and a methyl group are preferable, and among them, a hydrogen atom is particularly preferable from the viewpoint of improving hue and light fastness.

In the case where G ₁ , G ₂ , Y ₁ , Y ₂ , W ₁ , W ₂ , R ₁₁ , R ₁₂ , and Z further have a substituent, the following substituent (hereinafter referred to as “substituent J”) May be referred to).

(Substituent J)
For example, halogen atom, alkyl group, aralkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, cyano group, hydroxyl group, nitro group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group , Carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl or arylsulfonylamino group , Mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, alkyl or arylsulfinyl group, alkyl or arylsulfonyl group, acyl group, aryloxycarboni Group, an alkoxycarbonyl group, a carbamoyl group, an aryl or heterocyclic azo group, an imido group, a phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, a silyl group.

Each group of the substituent J will be further described.
As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom is mentioned, for example.

  Examples of the alkyl group include linear, branched, and cyclic substituted or unsubstituted alkyl groups, and include cycloalkyl groups, bicycloalkyl groups, and tricyclo structures having many ring structures. An alkyl group (for example, an alkyl group of an alkoxy group or an alkylthio group) in a substituent described below also represents such an alkyl group. Specifically, the alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, such as a methyl group, ethyl group, n-propyl group, isopropyl group, t-butyl group, n-octyl group, eicosyl group, 2-chloroethyl group, 2-cyanoethyl group, 2-ethylhexyl group and the like can be mentioned, and the cycloalkyl group is preferably a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, for example, cyclohexyl group, cyclopentyl group. 4-n-dodecylcyclohexyl group and the like, and the bicycloalkyl group is preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a bicycloalkane having 5 to 30 carbon atoms to a hydrogen atom. A monovalent group such as a bicyclo [1,2,2] heptan-2-yl group, bicycl [2,2,2] octan-3-yl group.

  Examples of the aralkyl group include a substituted or unsubstituted aralkyl group, and the substituted or unsubstituted aralkyl group is preferably an aralkyl group having 7 to 30 carbon atoms. For example, a benzyl group and a 2-phenethyl group can be mentioned.

  Examples of the alkenyl group include linear, branched, and cyclic substituted or unsubstituted alkenyl groups, and include cycloalkenyl groups and bicycloalkenyl groups. Specifically, the alkenyl group is preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, such as a vinyl group, an allyl group, a prenyl group, a geranyl group, an oleyl group, and the like. Is preferably a substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom of a cycloalkene having 3 to 30 carbon atoms, such as 2-cyclopentene-1 -Yl group, 2-cyclohexen-1-yl group and the like, and as the bicycloalkenyl group, a substituted or unsubstituted bicycloalkenyl group, preferably a substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms, That is, a monovalent group obtained by removing one hydrogen atom of a bicycloalkene having one double bond, for example, bicyclo [2 2,1] hept-2-en-1-yl group, a bicyclo [2,2,2] oct-2-en-4-yl group and the like.

  The alkynyl group is preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms such as an ethynyl group, a propargyl group, and a trimethylsilylethynyl group.

  The aryl group is preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, such as a phenyl group, a p-tolyl group, a naphthyl group, an m-chlorophenyl group, an o-hexadecanoylaminophenyl group, and the like. Can be mentioned.

  The heterocyclic group is preferably a monovalent group obtained by removing one hydrogen atom from a 5- or 6-membered substituted or unsubstituted aromatic or non-aromatic heterocyclic compound, and more preferably a carbon number. Examples thereof include 3 to 30 5- or 6-membered aromatic heterocyclic groups such as a 2-furyl group, a 2-thienyl group, a 2-pyrimidinyl group, and a 2-benzothiazolyl group.

  The alkoxy group is preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, such as a methoxy group, an ethoxy group, an isopropoxy group, a t-butoxy group, an n-octyloxy group, or a 2-methoxyethoxy group. Etc.

  The aryloxy group is preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, such as a phenoxy group, 2-methylphenoxy group, 4-t-butylphenoxy group, 3-nitrophenoxy group, 2 -Tetradecanoylaminophenoxy group etc. are mentioned.

  Preferred examples of the silyloxy group include substituted or unsubstituted silyloxy groups having 0 to 20 carbon atoms such as a trimethylsilyloxy group and a diphenylmethylsilyloxy group.

  Preferred examples of the heterocyclic oxy group include substituted or unsubstituted heterocyclic oxy groups having 2 to 30 carbon atoms, such as a 1-phenyltetrazole-5-oxy group and a 2-tetrahydropyranyloxy group.

  The acyloxy group is preferably a formyloxy group, a substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms, such as an acetyloxy group, Examples include a pivaloyloxy group, a stearoyloxy group, a benzoyloxy group, and a p-methoxyphenylcarbonyloxy group.

  The carbamoyloxy group is preferably a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms, such as N, N-dimethylcarbamoyloxy group, N, N-diethylcarbamoyloxy group, morpholinocarbonyloxy group, N , N-di-n-octylaminocarbonyloxy group, Nn-octylcarbamoyloxy group and the like.

  The alkoxycarbonyloxy group is preferably a substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, such as a methoxycarbonyloxy group, an ethoxycarbonyloxy group, a t-butoxycarbonyloxy group, or an n-octylcarbonyloxy group. Etc.

  The aryloxycarbonyloxy group is preferably a substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, such as phenoxycarbonyloxy group, p-methoxyphenoxycarbonyloxy group, pn-hexadecyloxy. Examples include phenoxycarbonyloxy group.

  The amino group includes an alkylamino group, an arylamino group, and a heterocyclic amino group, preferably an amino group, a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, a substituted or unsubstituted group having 6 to 30 carbon atoms. Examples of the substituted anilino group include a methylamino group, a dimethylamino group, an anilino group, an N-methyl-anilino group, and a diphenylamino group.

  The acylamino group is preferably a formylamino group, a substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, a substituted or unsubstituted arylcarbonylamino group having 6 to 30 carbon atoms, such as an acetylamino group, Examples include pivaloylamino group, lauroylamino group, benzoylamino group, 3,4,5-tri-n-octyloxyphenylcarbonylamino group, and the like.

  The aminocarbonylamino group is preferably a substituted or unsubstituted aminocarbonylamino group having 1 to 30 carbon atoms, such as a carbamoylamino group, N, N-dimethylaminocarbonylamino group, or N, N-diethylaminocarbonylamino group. And a morpholinocarbonylamino group.

  The alkoxycarbonylamino group is preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, such as methoxycarbonylamino group, ethoxycarbonylamino group, t-butoxycarbonylamino group, n-octadecyloxycarbonylamino. Group, N-methyl-methoxycarbonylamino group and the like.

  The aryloxycarbonylamino group is preferably a substituted or unsubstituted aryloxycarbonylamino group having 7 to 30 carbon atoms, such as phenoxycarbonylamino group, p-chlorophenoxycarbonylamino group, mn-octyloxyphenoxy. Examples thereof include a carbonylamino group.

  The sulfamoylamino group is preferably a substituted or unsubstituted sulfamoylamino group having 0 to 30 carbon atoms, such as a sulfamoylamino group, N, N-dimethylaminosulfonylamino group, Nn- Examples include octylaminosulfonylamino group.

The alkyl or arylsulfonylamino group is preferably a substituted or unsubstituted alkylsulfonylamino group having 1 to 30 carbon atoms, a substituted or unsubstituted arylsulfonylamino group having 6 to 30 carbon atoms, such as a methylsulfonylamino group. Butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group, and the like.
Preferred examples of the alkylthio group include substituted or unsubstituted alkylthio groups having 1 to 30 carbon atoms, such as a methylthio group, an ethylthio group, and an n-hexadecylthio group.

  Preferred examples of the arylthio group include substituted or unsubstituted arylthio groups having 6 to 30 carbon atoms such as a phenylthio group, a p-chlorophenylthio group, and an m-methoxyphenylthio group.

  Preferred examples of the heterocyclic thio group include substituted or unsubstituted heterocyclic thio groups having 2 to 30 carbon atoms, such as a 2-benzothiazolylthio group and a 1-phenyltetrazol-5-ylthio group.

  The sulfamoyl group is preferably a substituted or unsubstituted sulfamoyl group having 0 to 30 carbon atoms, such as N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfuryl group. Examples include a famoyl group, an N-acetylsulfamoyl group, an N-benzoylsulfamoyl group, and an N- (N′-phenylcarbamoyl) sulfamoyl group.

  The alkyl or arylsulfinyl group is preferably a substituted or unsubstituted alkylsulfinyl group having 1 to 30 carbon atoms, a substituted or unsubstituted arylsulfinyl group having 6 to 30 carbon atoms, such as a methylsulfinyl group, an ethylsulfinyl group, phenyl. Examples thereof include a sulfinyl group and a p-methylphenylsulfinyl group.

  The alkyl or arylsulfonyl group is preferably a substituted or unsubstituted alkylsulfonyl group having 1 to 30 carbon atoms, a substituted or unsubstituted arylsulfonyl group having 6 to 30 carbon atoms, such as a methylsulfonyl group, an ethylsulfonyl group, or a phenyl group. A sulfonyl group, p-methylphenylsulfonyl group, etc. are mentioned.

  The acyl group is preferably a formyl group, a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyl group having 7 to 30 carbon atoms, a substituted or unsubstituted group having 2 to 30 carbon atoms. Heterocyclic carbonyl groups bonded to carbonyl groups at substituted carbon atoms, such as acetyl, pivaloyl, 2-chloroacetyl, stearoyl, benzoyl, pn-octyloxyphenylcarbonyl, 2-pyridyl Examples thereof include a carbonyl group and a 2-furylcarbonyl group.

  The aryloxycarbonyl group is preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms, such as phenoxycarbonyl group, o-chlorophenoxycarbonyl group, m-nitrophenoxycarbonyl group, pt- A butylphenoxycarbonyl group etc. are mentioned.

  The alkoxycarbonyl group is preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, a t-butoxycarbonyl group, and an n-octadecyloxycarbonyl group.

  The carbamoyl group is preferably a substituted or unsubstituted carbamoyl group having 1 to 30 carbon atoms, such as a carbamoyl group, an N-methylcarbamoyl group, an N, N-dimethylcarbamoyl group, or an N, N-di-n-octyl group. Examples thereof include a carbamoyl group and an N- (methylsulfonyl) carbamoyl group.

  The aryl or heterocyclic azo group is preferably a substituted or unsubstituted arylazo group having 6 to 30 carbon atoms, a substituted or unsubstituted heterocyclic azo group having 3 to 30 carbon atoms, such as phenylazo, p-chlorophenylazo, 5-ethylthio-1,3,4-thiadiazol-2-ylazo and the like.

  Preferred examples of the imide group include an N-succinimide group and an N-phthalimide group.

  The phosphino group is preferably a substituted or unsubstituted phosphino group having 0 to 30 carbon atoms, such as a dimethylphosphino group, a diphenylphosphino group, a methylphenoxyphosphino group, and the like.

  The phosphinyl group is preferably a substituted or unsubstituted phosphinyl group having 0 to 30 carbon atoms, such as a phosphinyl group, a dioctyloxyphosphinyl group, a diethoxyphosphinyl group, and the like.

  Preferred examples of the phosphinyloxy group include substituted or unsubstituted phosphinyloxy groups having 0 to 30 carbon atoms such as a diphenoxyphosphinyloxy group and a dioctyloxyphosphinyloxy group.

  The phosphinylamino group is preferably a substituted or unsubstituted phosphinylamino group having 0 to 30 carbon atoms, such as a dimethoxyphosphinylamino group or a dimethylaminophosphinylamino group.

  Preferred examples of the silyl group include substituted or unsubstituted silyl groups having 0 to 30 carbon atoms such as a trimethylsilyl group, a t-butyldimethylsilyl group, and a phenyldimethylsilyl group.

  Among the above substituents, those having a hydrogen atom may be substituted with the above substituent. Examples of such a substituent include an alkylcarbonylaminosulfonyl group, an arylcarbonylaminosulfonyl group, an alkylsulfonylaminocarbonyl group, and an arylsulfonylaminocarbonyl group. Examples thereof include a methylsulfonylaminocarbonyl group, a p-methylphenylsulfonylaminocarbonyl group, an acetylaminosulfonyl group, and a benzoylaminosulfonyl group.

  In addition, about the preferable combination of a substituent of the compound represented by the said General formula (1), the compound whose at least 1 of a various substituent is the said preferable group is preferable, and many more various substituents are the said preferable. More preferred are compounds that are groups, and most preferred are compounds in which all substituents are the preferred groups.

  A particularly preferable combination as the azo pigment represented by the general formula (1) of the present invention includes the following (A) to (E).

(A) W ₁ and W ₂ are each independently an alkoxy group (eg, methoxy group, ethoxy group, i-propoxy group, t-butoxy group), amino group (eg, —NH ₂ group, methylamino group, dimethyl group). Amino group, anilino group), alkyl group (for example, methyl group, ethyl group, n-propyl group, i-propyl group, t-butyl group, cyclopropyl group) or aryl group (for example, phenyl group, p-tolyl group) , A naphthyl group), among which an alkoxy group, an amino group or an alkyl group is preferable, an alkoxy group or an amino group is more preferable, and an alkoxy group having 1 to 5 carbon atoms or an amino group (-NH ₂ group) is more preferable. ) is the total alkylamino group having a carbon number of 1 to 5, particularly preferably, the total alkoxy group having a carbon number of 1-3, an amino group (-NH ₂ group), a total number of carbon atoms from 1 to 3 Alkylamino group, further, a methoxy group (-OCH ₃ group), an ethoxy group _(-OC 2 _{H 5} group), amino group (-NH ₂ group) are preferable, among which a methoxy group (-OCH ₃ group) is Most preferred.

(B) R ₁₁ and R ₁₂ are each independently a hydrogen atom or a substituent (for example, a substituted or unsubstituted acylamino group having 1 to 8 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms). Group, a substituted or unsubstituted aryl group having 6 to 18 carbon atoms in total, or a substituted or unsubstituted heterocyclic group having 4 to 12 carbon atoms in total, and more preferably a straight chain having 1 to 8 carbon atoms in total. It is an alkyl group or a branched alkyl group, more preferably a methyl group, an i-propyl group or a tert-butyl group, particularly preferably an i-propyl group or a t-butyl group, and most preferably a t-butyl group.

(C) Z represents a divalent 5- or 6-membered heterocyclic group, which may be further condensed. Z is preferably a 5- or 6-membered substituted or unsubstituted nitrogen-containing heterocycle, and more preferably a 6-membered substituted or unsubstituted nitrogen-containing heterocycle. For example, pyrrole ring, pyrazole ring, triazole ring, imidazole ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, thiadiazole ring, thiophene ring, furan ring, pyridine ring, pyrimidine ring, triazine ring, pyridazine ring, pyrazine A ring is preferred, and particularly preferred is a 6-membered nitrogen-containing heterocyclic ring, specifically a 6-membered nitrogen-containing heterocyclic group having 3 to 10 carbon atoms. Further preferred examples of the heterocyclic ring are a pyridine ring, a pyrimidine ring, an S-triazine ring, a pyridazine ring and a pyrazine ring, and more preferably a pyridine ring, a pyrimidine ring, an S-triazine ring, a pyridazine ring and a pyrazine ring. More preferred are a pyrimidine ring and an S-triazine ring, particularly a pyrimidine ring and an S-triazine ring. Further, a pyrimidine ring having a substituent at 4,6- and an alkoxy group having 1 to 4 carbon atoms at the 2-position. S-triazine ring is preferable, and among them, a pyrimidine ring having a substituent at 4,6- is most preferable.

(D) G ₁ and G ₂ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and particularly preferably a hydrogen atom or a methyl group. , Ethyl group, n-propyl group, isopropyl group, t-butyl group, cyclopropyl group, benzyl group, 2-phenethyl group, vinyl group, allyl group, ethynyl group, propargyl group, phenyl group, p-tolyl group, naphthyl Group, pyridyl group, pyrimidinyl group and pyrazinyl group are preferable, and further, hydrogen atom, methyl group, phenyl group, pyridyl group, pyrimidinyl group and pyrazinyl group are preferable, among which methyl group, 2-pyridyl group and 2,6-pyrimidinyl group are preferable. 2,5-pyrazinyl group is preferred, and methyl group is most preferred.

(E) Y ₁ and Y ₂ are each independently a hydrogen atom, an alkyl group (for example, a methyl group), an aryl group (for example, a phenyl group), a heterocyclic group (for example, a 2-pyridyl group), an alkylthio group (for example, a methylthio group) A hydrogen atom, a methyl group, a phenyl group, and a methylthio group, and among them, a hydrogen atom is most preferable.

The present invention includes within its scope tautomers of the azo pigments represented by the general formula (1).
The general formula (1) is shown in the form of an extreme structural formula among several tautomers that can be taken in terms of chemical structure, but may be a tautomer other than the structure described, You may use as a mixture containing these tautomers.
For example, the pigment represented by the general formula (1) may be an azo-hydrazone tautomer represented by the following general formula (1 ′).
The present invention includes in its scope a compound represented by the following general formula (1 ′), which is a tautomer of the azo pigment represented by the general formula (1).

(In General Formula (1 ′), R ₁₁ , R ₁₂ , W ₁ , W ₂ , Y ₁ , Y ₂ , G ₁ , G ₂ and Z are R ₁₁ , R ₁₂ , W _{1 in} General Formula (1). , W ₂ , Y ₁ , Y ₂ , G ₁ , G ₂ and Z.

  In addition, about the preferable combination of a substituent of the compound represented by the said General formula (1), the compound whose at least 1 of a various substituent is the said preferable group is preferable, and many more various substituents are the said preferable. More preferred are compounds that are groups, and most preferred are compounds in which all substituents are the preferred groups.

  Among the azo pigments represented by the general formula (1) of the present invention, an azo pigment represented by the following general formula (12) is preferable.

G ₁ , G ₂ , R ₁₁ , R ₁₂ , W ₁ , W ₂ , Y ₁ and Y ₂ in the general formula (12) are the same as G ₁ , G ₂ , R ₁₁ , _{R 12, W 1, W 2} , the same meaning as _{Y 1} and _{Y 2.}
Het. Represents a heterocycle formed by Z in the general formula (1), and X ₁₁ and X ₁₂ are each independently Het. Each represents a heteroatom in the heterocycle of which

Many tautomers can be considered in the azo pigment represented by the general formula (1).
In the present invention, the azo pigment represented by the general formula (1) preferably has a substituent that forms an intramolecular hydrogen bond or an intramolecular cross-hydrogen bond. It preferably has at least one substituent that forms an intramolecular hydrogen bond, more preferably has at least three substituents that form an intramolecular hydrogen bond, and at least three intramolecular hydrogens. It is particularly preferred that the group has a substituent that forms a bond, and at least two of these hydrogen bonds have a substituent that forms an intramolecular cross-hydrogen bond.

  Among the azo pigments represented by the general formula (1), examples of the particularly preferred azo pigments represented by the general formula (1) include azo pigments represented by the above general formula (12).

The reason why this structure is preferable is that, as shown in the general formula (12), a nitrogen atom, a hydrogen atom, and a heteroatom (a hydrazone group that is an azo group or a tautomer thereof) constituting a heterocycle contained in the azo pigment structure The nitrogen atom and the oxygen atom of the carbonyl group or the nitrogen atom of the amino group) can easily form at least one intramolecular hydrogen bond (intramolecular hydrogen bond).
More preferably, as shown in the general formula (12), a nitrogen atom, a hydrogen atom of an amino group and a hetero atom (a hydrazone group which is an azo group or a tautomer thereof) constituting a heterocyclic group contained in an azo pigment structure Of the carbonyl group and the oxygen atom of the carbonyl group or the nitrogen atom of the amino group) easily form at least four intramolecular hydrogen bonds, and easily form at least two intramolecular hydrogen bonds. It is easy to do.
As a result, the planarity of the molecule is improved, the intramolecular / intermolecular interaction is further improved, and for example, the crystallinity of the azo pigment represented by the general formula (12) is increased (it is easy to form a higher order structure). It is the most preferable example because the required performance as a pigment, which is light fastness, heat stability, wet heat stability, water resistance, gas resistance and / or solvent resistance, is greatly improved.

In the present invention, the compounds represented by the general formulas (1) and (12) can be applied even if they contain isotopes (eg, ² H, ³ H, ¹³ C, ¹⁵ N).

  In the present invention, an azo pigment represented by the following general formula (10) among the azo pigments represented by the general formulas (1) and (12) is more preferable from the viewpoint of effects, and is represented by the general formula (11). Particularly preferred are azo pigments.

(In General Formula (10), Z represents a 5- or 6-membered nitrogen-containing heterocycle, and W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group, or an aryl group.)

(In general formula (11), Z ′ represents a 6-membered nitrogen-containing heterocycle.)
In the general formula (11), examples of the 6-membered nitrogen-containing heterocycle represented by Z ′ include the same as the 6-membered nitrogen-containing heterocycle represented by Z in the general formula (1), and preferred examples thereof are also the same. .

  Specific examples of the azo pigments represented by the general formulas (1) and (12) are shown below, but the azo pigments used in the present invention are not limited to the following examples. The structures of the following specific examples are shown in the form of an ultimate structural formula among several tautomers that can be taken in terms of chemical structure, but have tautomeric structures other than those described. It goes without saying that it is also good.

Among the above, Pig. -1, Pig. -18, Pig. -25 is preferred.
In the present invention, even when a tautomer exists depending on the structure of the compound, it is described in one of the representative forms in the present invention, but a tautomer different from the description of the present invention is also present in the present invention. Azo pigments. Further, salts and hydrates of the azo pigments of the present invention are also included in the azo pigments of the present invention.

  The pigment represented by the general formula (1) of the present invention may have any chemical form as long as the chemical structural formula is the general formula (1) or a tautomer thereof, and may be any crystalline form called polymorph.

Crystal polymorphs refer to the same chemical composition but different arrangement of building blocks (molecules or ions) in the crystal. The crystal structure determines the chemical and physical properties, and each polymorph can be distinguished by its rheology, color, and other color characteristics. Different polymorphs can also be confirmed by X-Ray Diffraction (powder X-ray diffraction measurement result) or X-Ray Analysis (X-ray crystal structure analysis result).
When a crystal polymorph exists in the pigment represented by the general formula (1) of the present invention, any polymorph may be used, and a mixture of two or more polymorphs may be used. It is preferable to use a single component as the main component. That is, it is preferable that the crystalline polymorph is not mixed, and the content of the azo pigment having a single crystal type is 70% to 100%, preferably 80% to 100%, more preferably 90% with respect to the entire azo pigment. -100%, more preferably 95% -100, particularly preferably 100%. By using an azo pigment having a single crystal form as a main component, the regularity of the dye molecule arrangement is improved, the intramolecular / intermolecular interaction is strengthened, and a higher-order three-dimensional network is easily formed. . As a result, it is preferable in terms of performance required for pigments such as improvement of hue, light fastness, heat fastness, humidity fastness, oxidizing gas fastness and solvent resistance.
The mixing ratio of crystal polymorphs in azo pigments is based on solid physicochemical measurements such as single crystal X-ray crystal structure analysis, powder X-ray diffraction (XRD), crystal micrograph (TEM), IR (KBr method), etc. I can confirm.

  In the present invention, when the azo pigment represented by the general formula (1) has an acid group, a part or all of the acid group may be in a salt form. Type pigments may be mixed. Examples of the salt type include salts of alkali metals such as Na, Li, and K, ammonium salts that may be substituted with alkyl groups or hydroxyalkyl groups, and organic amine salts. Examples of organic amines include lower alkyl amines, hydroxy-substituted lower alkyl amines, carboxy-substituted lower alkyl amines, and polyamines having 2 to 10 alkyleneimine units having 2 to 4 carbon atoms. In the case of these salt types, the type is not limited to one type, and a plurality of types may be mixed.

  Further, in the structure of the pigment used in the present invention, when a plurality of acid groups are contained in one molecule, the plurality of acid groups may be salt type or acid type and may be different from each other.

  In the present invention, the azo pigment represented by the general formula (1) may be a hydrate containing water molecules in the crystal.

  Next, an example of a method for producing the azo pigment represented by the general formula (1) will be described. For example, the heterocyclic amine represented by the following general formula (A) is diazonium under acidic conditions, subjected to a coupling reaction with a compound represented by the following general formula (B), followed by post-treatment by a conventional method, An azo pigment represented by the formula (1) can be produced.

(In the general formulas (A) and (B), G, Y, W, R ₁₁ , R ₁₂ and Z are the corresponding G ₁ (or G ₂ ) and Y ₁ (or Y ₂ ) in the general formula (1)). , (W ₁ or W ₂ ), R ₁₁ , R ₁₂ and Z are synonymous.)

The heterocyclic amines represented by the above general formula (A) are generally known and commonly used methods such as those described in Helv. Chim. Acta, 41, 1958, 1052 to 1056 and Helv. Chim. Acta, 42, 1959, 349 to 352, etc., and a method analogous thereto.
The compound represented by the general formula (B) can be produced by the method described in International Publication No. 06/082669 and JP-A-2006-57076 and a method according thereto.
The diazoniumation reaction of the heterocyclic amine represented by the general formula (A) is, for example, in an acidic solvent such as sulfuric acid, phosphoric acid, acetic acid, hydrochloric acid, methanesulfonic acid, sodium nitrite, nitrosylsulfuric acid, isoamyl nitrite, etc. This reagent can be reacted at a temperature of 15 ° C. or lower for about 10 minutes to 6 hours.
The coupling reaction is performed by reacting the diazonium salt obtained by the above-described method with the compound represented by the general formula (B) at 40 ° C. or lower, preferably at 25 ° C. or lower for about 10 minutes to 12 hours. be able to.
In some cases, crystals are precipitated in this way, but in general, water or an alcohol solvent is added to the reaction solution to precipitate the crystals, and the crystals can be collected by filtration. it can. In addition, an alcohol solvent, water or the like can be added to the reaction solution to precipitate crystals, and the precipitated crystals can be collected by filtration. The crystals collected by filtration can be washed and dried as necessary to obtain an azo pigment represented by the general formula (1).

By the above production method, the compound represented by the general formula (1) is obtained as a crude azo pigment (crude). When used as the pigment of the present invention, it is desirable to carry out post-treatment. As the post-treatment method, for example, it is preferable to perform grinding treatment such as solvent salt milling, salt milling, dry milling, solvent milling, acid pasting, and the like. Of these, solvent salt milling is preferable.
Other post-treatments include a pigment particle control step by solvent heating treatment and the like, and a surface treatment step by resin, surfactant, dispersant and the like.

  Examples of the solvent used in the solvent heat treatment include water, aromatic hydrocarbon solvents such as toluene and xylene, halogenated hydrocarbon solvents such as chlorobenzene and o-dichlorobenzene, and alcohols such as isopropanol and isobutanol. Examples thereof include solvents, polar aprotic organic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, glacial acetic acid, pyridine, and mixtures thereof. An inorganic or organic acid or base may be further added to the solvents mentioned above. The temperature of the solvent heat treatment varies depending on the desired primary particle diameter of the pigment, but is preferably 40 to 150 ° C, more preferably 60 to 100 ° C. The treatment time is preferably 30 minutes to 24 hours.

Solvent salt milling is, for example, at least one selected from the group consisting of azo pigments, tautomers thereof, salts and hydrates thereof (hereinafter sometimes referred to as “azo pigments”), and water-soluble. This is a grinding process in which a mixture containing an inorganic salt and a water-soluble organic solvent is charged into a kneader and kneaded therein.
As the water-soluble inorganic salt, a commonly used water-soluble inorganic salt can be used without particular limitation. Specifically, it is preferable to use inorganic salts such as sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate. Moreover, 0.5-50 micrometers is preferable, as for the average particle diameter of the water-soluble inorganic salt to be used, 1-20 micrometers is more preferable, and 1-10 micrometers is still more preferable. The amount of the inorganic salt used can be 1 to 30 times by mass with respect to the azo pigment and the like, and preferably 3 to 20 times by mass and 5 to 15 times by mass from the viewpoint of productivity. More preferred.
The water-soluble organic solvent is preferably a solvent that dissolves in water and does not substantially dissolve the azo pigment and the water-soluble inorganic salt. Since the solvent easily evaporates due to a temperature rise during kneading, From the viewpoint, a high boiling point solvent is preferable. The water-soluble organic solvent can be used to adjust the mixture containing the crude azo pigment and the water-soluble inorganic salt to a hardness applicable to kneading. Examples of such water-soluble organic solvents include diethylene glycol, glycerin, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (isopentyloxy). Ethanol, 2- (hexyloxy) ethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol , Dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, di B propylene glycol or mixtures thereof. The amount of the water-soluble organic solvent used is preferably 0.1 to 5 times by mass with respect to the azo pigment or the like. The kneading temperature is preferably 20 to 130 ° C, particularly preferably 40 to 110 ° C. As a kneader, for example, a kneader or a mix muller can be used.

<Vinyl polymer>
The vinyl polymer used in the present invention includes a hydrophobic structural unit (a) represented by the following general formula (PI) and a hydrophilic structural unit (b).

(In General Formula (PI), R ₁ represents a hydrogen atom, a methyl group, or a halogen atom, and L ₁ represents —COO—, —OCO—, —CONR ₂ —, —O—, or substituted or unsubstituted. R ₂ represents a hydrogen atom or an alkyl group, L ₂ represents a single bond or a divalent linking group, and Ar ₁ represents a monovalent group derived from an aromatic ring.)

(Hydrophobic structural unit (a) represented by the general formula (PI))
The content of the hydrophobic structural unit (a) represented by the general formula (PI) (hereinafter sometimes simply referred to as “hydrophobic structural unit (a)”) depends on the dispersion stability and ejection accuracy of the pigment. From the viewpoint of detergency, it is preferably 10% by mass or more and less than 75% by mass of the total mass of the vinyl polymer, more preferably 20% by mass or more and less than 70% by mass, and 30% by mass or more and 60% by mass. It is particularly preferred that it is less than%.

R ₁ represents a hydrogen atom, a methyl group, or a halogen atom, more preferably a hydrogen atom or a methyl group, and still more preferably a methyl group.

The alkyl group represented by R ₂ is preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, and a t-butyl group. it can.
Here, examples of the substituent include, but are not limited to, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group, and a cyano group.

L ₁ represents —COO—, —OCO—, —CONR ₂ —, —O—, or a substituted or unsubstituted phenylene group, preferably —COO—.
When L ₂ is a divalent linking group, it is preferably a linking group having 1 to 30 carbon atoms, more preferably a linking group having 1 to 25 carbon atoms, and still more preferably a linking group having 1 to 20 carbon atoms. It is. Among these, a divalent linking group having 1 to 25 carbon atoms including at least one selected from an alkyleneoxy group and an alkylene group is preferable, and — (CH ₂ —CH ₂ ) _n —, — (CH ₂ O) _n - or _{- (CH 2 -CH 2 -O)} n - (n represents the number of repeating units of the average, a n = 1 to 6, n is preferably 1 or 2, more preferably 1) it is Is preferred.

The aromatic ring in Ar ₁ is not particularly limited, and examples thereof include a benzene ring, a condensed aromatic ring having 8 to 18 carbon atoms, a hetero ring in which an aromatic ring is condensed, or a benzene ring in which two or more are connected. It is done.

  The condensed aromatic ring having 8 or more carbon atoms is an aromatic ring in which at least two or more benzene rings are condensed and / or an alicyclic carbonization in which at least one aromatic ring is condensed with the aromatic ring. An aromatic compound having 8 or more carbon atoms in which a ring is formed of hydrogen. Specific examples include naphthalene ring, anthracene ring, fluorene ring, phenanthrene ring, acenaphthene ring and the like.

  The heterocyclic ring condensed with the aromatic ring is a compound in which an aromatic compound not containing a hetero atom (preferably a benzene ring) and a cyclic compound having a hetero atom are condensed at least. Here, the cyclic compound having a hetero atom is preferably a 5-membered ring or a 6-membered ring. As a hetero atom, a nitrogen atom, an oxygen atom, or a sulfur atom is preferable. The cyclic compound having a hetero atom may have a plurality of hetero atoms, and in this case, the hetero atoms may be the same as or different from each other. Specific examples of the heterocyclic ring condensed with an aromatic ring include a phthalimide ring, an acridone ring, a carbazole ring, a benzoxazole ring, and a benzothiazole ring.

The hydrophobic structural unit (a) represented by the general formula (PI) is preferably at least one selected from structural units derived from acrylate and (meth) acrylate. If it is at least one selected from structural units derived from acrylate and (meth) acrylate, an aromatic ring can be bonded to the main chain via an ester bond, and mutual properties such as adsorptivity to the pigment can be obtained. An aromatic ring that can be expected to act can take a three-dimensional structure with a degree of freedom from the main chain.
In addition, the hydrophobic structural unit (a) represented by the general formula (PI) is connected to a benzene ring, a condensed aromatic ring having 8 or more carbon atoms, a heterocyclic ring condensed with an aromatic ring, or two or more. It preferably contains a monovalent group derived from a benzene ring. This is because the use of the aromatic ring can exert interaction such as adsorptivity with the pigment.

Ar ₁ is preferably a benzene ring, naphthalene ring, anthracene ring, fluorene ring, phenanthrene ring, acenaphthene ring, phthalimide ring, acridone ring, carbazole ring, benzoxazole ring, or benzothiazole ring, and a benzene ring, naphthalene ring, acridone ring Is more preferable, and a benzene ring is still more preferable.

Among the above general formula (PI), R ₁ is a hydrogen atom or a methyl group, L ₁ is (main chain side) —COO—, and L ₂ is at least selected from an alkyleneoxy group and an alkylene group. Preferred is a combination of structural units each having 1 to 25 carbon atoms and a divalent linking group in which Ar ₁ is an aryl ring, more preferably, R ₁ is a hydrogen atom or a methyl group, and L ₁ is (Main chain side) —COO—, L ₂ is (main chain side) — (CH ₂ —CH ₂ —O) _n — (n represents the average number of repeating units, and n = 1 to 6 And n is preferably 1 or 2, and more preferably ₁ ), and Ar ₁ is a combination of structural units each having a benzene ring.

  Specific examples of the monomer that can form the hydrophobic structural unit (a) represented by the general formula (PI) are given below, but the present invention is not limited to the following specific examples.

In the present invention, among the hydrophobic structural units (a) represented by the general formula (PI), any of benzyl acrylate, benzyl methacrylate, phenoxyethyl acrylate, and phenoxyethyl methacrylate is used from the viewpoint of dispersion stability. The structural unit is preferably derived from at least one selected from the above, and more preferably contains at least one selected from phenoxyethyl methacrylate, benzyl acrylate and benzyl methacrylate.
In the present invention, the hydrophobic structural unit (a) preferably contains 20% by mass or more of structural units derived from phenoxyethyl (meth) acrylate, based on the total mass of the vinyl polymer, more preferably 20 to 80% by mass. It is more preferable to include.

(Hydrophobic structural unit (a2))
The vinyl polymer used in the present invention contains a hydrophobic structural unit (a2) derived from an alkyl ester of acrylic acid or methacrylic acid in addition to the hydrophobic structural unit (a) as a hydrophobic structural unit. Also good.
The alkyl ester preferably has 1 to 18 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably 1 to 4 carbon atoms, and particularly preferably 1 to 2 carbon atoms.
The content of the hydrophobic structural unit (a2) is preferably 5% by mass to 70% by mass and more preferably 20% by mass to 60% by mass in the polymer vinyl polymer.
Specific examples of the hydrophobic structural unit (a2) include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, cyclohexyl ( Examples include (meth) acrylates such as (meth) acrylate, dodecyl (meth) acrylate, and stearyl (meth) acrylate. Of these, methyl (meth) acrylate, ethyl (meth) acrylate, and cyclohexyl (meth) acrylate are preferred.

<Hydrophilic structural unit (b)>
The hydrophilic structural unit (b) contained in the vinyl polymer in the present invention will be described.
Examples of the hydrophilic structural unit (b) include carboxylic acid-containing acrylic acid and methacrylic acid. Moreover, the hydrophilic structural unit containing a nonionic hydrophilic group can be mentioned.

Examples of the hydrophilic structural unit (b) include (meth) acrylates, (meth) acrylamides and vinyl esters having a hydrophilic functional group.
Examples of the hydrophilic functional group include a hydroxyl group, an amino group, an amide group (with a nitrogen atom unsubstituted), and an alkylene oxide polymer such as polyethylene oxide and polypropylene oxide as described later.
Of these, hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, (meth) acrylamide, aminoethyl acrylate, aminopropyl acrylate, and (meth) acrylate containing an alkylene oxide polymer are particularly preferable.

Examples of the hydrophilic structural unit (b) include hydrophilic structural units having an alkylene oxide polymer structure.
As alkylene of the said alkylene oxide polymer, C1-C6 is preferable from a hydrophilic viewpoint, C2-C6 is more preferable, C2-C4 is especially preferable.
Moreover, as a polymerization degree of the said alkylene oxide polymer, 1-120 are preferable, 1-60 are more preferable, and 1-30 are especially preferable.

  Examples of the hydrophilic structural unit (b) include hydrophilic structural units containing a hydroxyl group. The number of hydroxyl groups is not particularly limited, and is preferably 1 to 4, more preferably 1 to 3, and particularly preferably 1 to 2 from the viewpoint of hydrophilicity of the vinyl polymer and compatibility with the solvent and other monomers during polymerization. preferable.

  Preferable examples of the hydrophilic structural unit (b) include acrylic acid and methacrylic acid.

  The content of the hydrophilic structural unit (b) is preferably 4% by mass or more and 40% by mass or less, preferably 6% by mass or more and 25% by mass or less, and 8% by mass or more and 15% by mass with respect to the total mass of the vinyl polymer. The following is more preferable.

<Structural unit (c)>
As described above, the vinyl polymer in the present invention is a structural unit (d) having a structure different from the hydrophobic structural unit (a), the hydrophobic structural unit (b), and the hydrophilic structural unit (b) ( Hereinafter, it may be simply referred to as “structural unit (d)”.
The content of the structural unit (a2) is preferably 15% by mass to 80% by mass, preferably 25% by mass to 70% by mass, and preferably 40% by mass to 60% by mass with respect to the total mass of the vinyl polymer. More preferred.

The monomer in the case where the structural unit (c) is a hydrophobic structural unit is not particularly limited as long as it has a functional group capable of forming a polymer and a hydrophobic functional group, and any known monomers Can also be used.
As the monomer capable of forming the hydrophobic structural unit, vinyl monomers and ((meth) acrylamides, styrenes, vinyl esters, etc.) are preferable from the viewpoints of availability, handleability, and versatility.

  Examples of (meth) acrylamides include (meth) acrylamides such as N-cyclohexyl (meth) acrylamide, N- (2-methoxyethyl) (meth) acrylamide, N, N-diallyl (meth) acrylamide, and N-allyl (meth) acrylamide. ) Acrylamides.

  Styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, iso i-propyl styrene, n-butyl styrene, tert-butyl styrene, methoxy styrene, butoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, Examples include bromostyrene, chloromethylstyrene, methyl vinylbenzoate, α-methylstyrene, vinylnaphthalene, and the like, and styrene and α-methylstyrene are preferable.

Examples of the vinyl esters include vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl methoxyacetate, and vinyl benzoate. Of these, vinyl acetate is preferable.
These can be used alone or in admixture of two or more.

The vinyl polymer may be composed of only the hydrophobic structural unit (a) and the hydrophilic structural unit (b).
More preferably, as the water-based ink, at least one selected from the structural unit derived from phenoxyethyl (meth) acrylate and the structural unit derived from benzyl (meth) acrylate is used as the hydrophobic structural unit (a) of the vinyl polymer. At least one selected from the structural units derived from acrylic acid and methacrylic acid, wherein the total amount is 20% by mass or more (preferably 20 to 80% by mass) with respect to the total mass of the vinyl polymer. Is more preferably 30% by mass or less (preferably 8 to 30% by mass) based on the total mass of the vinyl polymer.

The acid value of the vinyl polymer of the present invention is preferably from 30 mgKOH / g to 300 mgKOH / g, more preferably from 40 mgKOH / g to less than 150 mgKOH / g, from the viewpoint of pigment dispersibility and storage stability. It is particularly preferably 50 mgKOH / g or more and 100 mgKOH / g.
The acid value here is defined by the mass (mg) of KOH required to completely neutralize 1 g of the vinyl polymer, and can be measured by the method described in JIS standards (JIS K0070, 1992).

  The vinyl polymer in the present invention may be a random copolymer in which each structural unit is irregularly introduced, or may be a block copolymer in which the structural units are regularly introduced. These structural units may be synthesized in any order of introduction, and the same constituent components may be used twice or more. However, a random copolymer is used in terms of versatility and manufacturability. preferable.

Furthermore, the molecular weight range of the vinyl polymer used in the present invention is a mass average molecular weight (Mw), preferably 30,000 to 150,000, more preferably 30,000 to 100,000, and still more preferably 30,000 to 80,000. It is.
By setting the molecular weight within the above range, the steric repulsion effect as a dispersing agent tends to be good, and it is preferable from the viewpoint of the tendency that adsorption to the pigment does not take time due to the steric effect.
The molecular weight distribution (expressed by mass average molecular weight value / number average molecular weight value) of the vinyl polymer used in the present invention is preferably 1 to 6, and more preferably 1 to 4.
Setting the molecular weight distribution in the above range is preferable from the viewpoints of ink dispersion stability and ejection stability. Here, the number average molecular weight and the mass average molecular weight are detected by a solvent THF and a differential refractometer using a GPC analyzer using columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all trade names manufactured by Tosoh Corporation). The molecular weight is expressed using polystyrene as a standard substance.

The vinyl polymer used in the present invention can be synthesized by various polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization, precipitation polymerization, bulk polymerization, and emulsion polymerization. The polymerization reaction can be performed by a known operation such as a batch system, a semi-continuous system, or a continuous system.
The polymerization initiation method includes a method using a radical initiator, a method of irradiating light or radiation, and the like. These polymerization methods and polymerization initiation methods are, for example, the revised version of Tsuruta Junji “Polymer Synthesis Method” (published by Nikkan Kogyo Shimbun, 1971), Takatsu Otsu, Masato Kinoshita, “Experimental Methods for Polymer Synthesis” It is described in pp. 47-154 published in 1972.
Among the above polymerization methods, a solution polymerization method using a radical initiator is particularly preferable. Solvents used in the solution polymerization method are, for example, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, benzene, toluene, acetonitrile, A single organic solvent such as methylene chloride, chloroform, dichloroethane, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol, or a mixture of two or more thereof may be used, or a mixed solvent with water may be used.
The polymerization temperature needs to be set in relation to the molecular weight of the polymer to be produced, the type of initiator, etc., and is usually about 0 ° C. to 100 ° C., but the polymerization is preferably carried out in the range of 50 to 100 ° C.
The reaction pressure can be appropriately selected, but is usually preferably 1 to 100 kg / cm ² , particularly preferably about 1 to 30 kg / cm ² . The reaction time is about 5 to 30 hours. The obtained resin may be subjected to purification such as reprecipitation.

  From the viewpoint of dispersion stability, the ratio of the vinyl polymer added in the present invention is preferably in the range of 10% to 100%, more preferably 30% to 60%, based on the weight of the pigment.

<Colorant>
The colorant in the present invention is represented by (A) the azo pigment represented by the general formula (1), a tautomer thereof, a salt or a hydrate thereof, and (B) the general formula (PI). A vinyl polymer (hereinafter also referred to as “resin” or “specific resin”) containing the hydrophobic structural unit (a) and the hydrophilic structural unit (b). Preferably, it is a vinyl polymer particle containing said (A) and (B).
The vinyl polymer particles containing the pigment in the present invention can be produced by a conventional physical and chemical method using a specific resin and a pigment. For example, as described in JP-A-9-151342, JP-A-10-140065, JP-A-11-209672, JP-A-11-172180, JP-A-10-25440, or JP-A-11-43636. It can be manufactured by a method. Specific examples include the phase inversion method and acid precipitation method described in JP-A-9-151342 and JP-A-10-140065. Among them, the phase inversion method is preferable from the viewpoint of dispersion stability.
The specific resin preferably includes a hydrophobic structural unit (a) and a hydrophilic structural unit (b).

a) Phase inversion method The phase inversion method is basically a method of self-dispersing (phase-inversion emulsification) in which a mixed melt of a resin having self-dispersibility or solubility and a pigment is dispersed in water. The contained vinyl polymer particles can be obtained. Here, the mixed molten material refers to a mixed state that is not dissolved, a state that is dissolved and mixed, or a state that includes both of these states. A more specific production method of the “phase inversion method” includes the method described in JP-A-10-140065.
b) Acid precipitation method The acid precipitation method prepares a water-containing cake composed of a resin and a pigment, and neutralizes some or all of the anionic groups of the resin in the water-containing cake using a basic compound. This is a method for producing vinyl polymer particles containing a pigment.
Specifically, the acid precipitation method includes (1) a step of dispersing a resin and a pigment in an alkaline aqueous medium and subjecting the resin to gelation by performing a heat treatment as necessary; Hydrophobizing the resin by making it neutral or acidic, and strongly fixing the resin to the pigment; (3) obtaining a water-containing cake by performing filtration and washing as necessary; and (4) a water-containing cake. A step of neutralizing a part or all of the anionic group of the resin with a basic compound and then redispersing in an aqueous medium, and (5) performing a heat treatment as necessary, And a step of gelling the resin.

  More specific production methods of the above phase inversion method and acid precipitation method include the methods described in JP-A-9-151342 and JP-A-10-140065.

In the water-based ink of the present invention, the vinyl polymer particles containing a pigment are a vinyl containing pigment by a step of obtaining a specific resin as an aqueous dispersion, specifically, a method including the following steps (1) and (2). A preparation step for preparing a dispersion of polymer particles can be provided, and the production of the water-based ink of the present invention includes the preparation step, and the dispersion of vinyl polymer particles containing the obtained pigment is added to water. And water-soluble organic solvent.
Step (1): Step of obtaining a dispersion by dispersing a mixture containing the specific resin, organic solvent, neutralizing agent, pigment, and water in the present invention described above by stirring or the like Step (2): From the dispersion Removing the organic solvent

The stirring method is not particularly limited, and a commonly used mixing and stirring device, and a dispersing device such as an ultrasonic dispersing device, a high-pressure homogenizer, and a bead mill can be used as necessary. In the present invention, the dispersion treatment can be performed using, for example, a ball mill, a roll mill, a bead mill, a high-pressure homogenizer, a high-speed stirring type disperser, an ultrasonic homogenizer, or the like.
As a dispersion method, either medialess dispersion or media dispersion may be used, but medialess dispersion is preferable.

As medialess dispersion, dispersion treatment using a high-pressure homogenizer is preferable.
As for the high-pressure homogenizer treatment, in the conventional dispersion treatment using a high-pressure homogenizer using a pigment, in order to improve dispersibility, first, dispersion using a bead mill using a dispersion medium such as zirconia beads has been performed. This is because the normal dispersibility of pigments requires a strong shearing force in order to obtain a pigment dispersion having a desired particle size distribution.
On the other hand, since the azo pigment represented by the general formula (1) used in the present invention is excellent in dispersibility, it is dispersed by a high-pressure homogenizer that does not use a dispersion medium, and has a desired particle size distribution and coarse particle number. Can be obtained.
The high-pressure homogenizer used in the present invention is not particularly limited, and specific examples of commercially available devices include a gorin homogenizer, a microfluidizer, a starburst, and DeBEE2000.

  The processing pressure of the high-pressure homogenizer is preferably 100 to 150 Mpa, and more preferably 120 to 150 Mpa. Further, the number of passes of the high-pressure homogenizer treatment is preferably 1 to 10 passes, more preferably 2 to 6 passes, and further preferably 2 to 4 passes. In the conventional pigment dispersion using a high-pressure homogenizer, even when the dispersion medium dispersion treatment is performed in advance, the treatment pressure is required to be 150 MPa or more, and the number of passes is required to be 6 passes or more. Since the processing pressure and the number of passes can be suppressed to a small value, the manufacturing process can be simplified.

Preferred examples of the organic solvent used in the above step (1) include alcohol solvents, ketone solvents, and ether solvents.
Examples of the alcohol solvent include iso i-propyl alcohol, n-butanol, t-butanol, ethanol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ether solvent include dibutyl ether and dioxane. Among these solvents, ketone solvents such as methyl ethyl ketone and alcohol solvents such as iso-propyl alcohol are preferable, and methyl ethyl ketone is most preferable.

  The neutralizing agent used in the above step (1) is used in order to form an emulsified or dispersed state in which part or all of the dissociable group is neutralized and the specific resin is stable in water. When the specific resin has an anionic dissociative group as a dissociable group, examples of the neutralizing agent used include basic compounds such as organic amine compounds, ammonia, and alkali metal hydroxides. Examples of the organic amine compound include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, monoethanolamine, diethanolamine, triethanolamine, N, N-dimethyl-ethanolamine. N, N-diethyl-ethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, N-methyldiethanolamine, N-ethyldiethanolanine, monoisopropanolamine, Examples include diisopropanolamine and triisopropanolamine. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Of these, sodium hydroxide, potassium hydroxide, triethylamine, and triethanolamine are preferable from the viewpoint of stabilizing dispersion in water, and sodium hydroxide and potassium hydroxide are particularly preferable.

  The content of the basic compound is preferably in the range of 5 to 120 mol%, more preferably in the range of 10 to 120 mol%, and still more preferably in the range of 80 to 120 mol% with respect to 100 mol% of the dissociable group. . When the content is 5 mol% or more, it is effective for stabilizing the dispersion in water, and when it is 120 mol% or less, there is an effect of reducing water-soluble components.

  In the step (2), an organic solvent is distilled off from the dispersion obtained in the step (1) by a conventional method such as distillation under reduced pressure, and the phase is changed to an aqueous system, whereby the pigment particle surface becomes the resin. A dispersion of vinyl polymer particles containing the pigment coated with can be obtained. The organic solvent in the obtained dispersion is substantially removed, and the amount of the organic solvent here is preferably 0.2% by mass or less, and more preferably 0.1% by mass or less.

More specifically, for example, (1) a step of neutralizing a solution of a specific resin in the present invention having an anionic group dissolved in an organic solvent, a basic compound (neutralizing agent), and water. (2) A step of mixing the obtained liquid mixture with a pigment to form a suspension, and then dispersing the pigment with a disperser or the like to obtain a pigment dispersion liquid; and (3) removing the organic solvent by, for example, distillation. Then, the pigment is coated with a specific resin having an anionic group and dispersed in an aqueous medium to form an aqueous dispersion, whereby an aqueous ink can be produced.
More specifically, the descriptions of JP-A-11-2096722 and JP-A-11-172180 can be referred to.

The average particle diameter of the vinyl polymer particles containing the pigment contained in the aqueous ink of the present invention is preferably in the range of 10 to 400 nm, more preferably in the range of 10 to 200 nm, and still more preferably in the range of 50 to 150 nm. . When the average particle size is 10 nm or more, the production suitability is improved, and when it is 400 nm or less, the storage stability is improved. In addition, there is no restriction | limiting in particular regarding the particle size distribution of the vinyl polymer particle containing a pigment, Either a thing with a wide particle size distribution or a thing with a monodispersed particle size distribution may be sufficient.
The average particle size and particle size distribution of the vinyl polymer particles containing the pigment are measured by a dynamic light scattering method using a nanotrack particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.). Is required.

The content of the vinyl polymer particles in the water-based ink in the present invention is preferably 1 to 15% by mass, more preferably 2 to 8% by mass, from the viewpoint of dispersion stability and concentration of the aqueous ink for inkjet recording. 7% by mass is particularly preferable.
In the ink composition, the content of the azo pigment represented by the general formula (1) is preferably 0.1 to 20% by mass, and more preferably 0.2 to 10% by mass. .

<Organic monophosphonic acid compound>
The water-based ink of the present invention contains a compound represented by the following general formula (2).

(In general formula (2), R represents the following 1) or 2).
1) unsubstituted or alkyl group substituted by hydroxyl group, amino group, nitro group or carboxyl group,
2) A phenyl group which is unsubstituted or substituted with an amino group, an alkyl group or a hydroxyl group. )

  Since the water-based ink of the present invention contains the compound represented by the general formula (2), drying shrinkage of the ink film on paper can be suppressed and diffuse reflection of light on the ink film surface can be suppressed. Glossiness can be improved.

R in the compound represented by the general formula (2) will be described.
When R is unsubstituted or represents an alkyl group substituted with a hydroxyl group, amino group, nitro group or carboxyl group, the unsubstituted alkyl group is a linear or branched chain or cyclic Any of these alkyl groups may be sufficient, a C1-C6 alkyl group is preferable, and a C2-C4 alkyl group is more preferable.
Examples of the linear or branched chain alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, sec-butyl group, n-pentyl group, Isopentyl group, tert-pentyl group, sec-pentyl group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethylbutyl group, 2 -Ethylbutyl group, 1-ethyl-2-methylpropyl group, etc. are mentioned.
Examples of the cyclic alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.
When R is 1), an unsubstituted, hydroxyl group, or alkyl group substituted with a carboxyl group is preferred. In this case, the substituent that the alkyl group has is preferably a hydroxyl group or a carboxyl group, and more preferably a carboxyl group.

When R is 2) unsubstituted or a phenyl group substituted with an amino group, an alkyl group or a hydroxyl group, the alkyl group substituted on the phenyl group is preferably an alkyl group having 1 to 6 carbon atoms, Two to four alkyl groups are more preferred. Specific examples include those exemplified as the alkyl group when R is 1).
As the substituent substituted on the phenyl group, an alkyl group is preferable.
Specific examples of the compound represented by the general formula (2) when R is 2) include phenylphosphonic acid, methylphenylphosphonic acid, ethylphenylphosphonic acid, butylphenylphosphonic acid, hydroxyphenylphosphonic acid, aminophenylphosphonic An acid etc. are mentioned.

  Among the compounds represented by the general formula (2), compounds in which R is a carboxyl group-substituted or unsubstituted alkyl group or a phenyl group are preferable.

  Specific examples of the compound represented by the general formula (2) include ethylphosphonic acid, n-propylphosphonic acid, i-propylphosphonic acid, n-butylphosphonic acid, t-butylphosphonic acid, phenylphosphonic acid, o -Methyl-phenylphosphonic acid, m-methyl-phenylphosphonic acid, p-methyl-phenylphosphonic acid, o-ethyl-phenylphosphonic acid, m-ethyl-phenylphosphonic acid, p-ethyl-phenylphosphonic acid, ot -Butyl-phenylphosphonic acid, m-t-butyl-phenylphosphonic acid, p-t-butyl-phenylphosphonic acid, p-hydroxy-phenylphosphonic acid, m-hydroxy-phenylphosphonic acid, o-hydroxy-phenylphosphonic acid 2,2-dimethylpropylphosphonic acid, cyclohexylphosphonic acid, n-hexylphosphonic acid Examples include acid, o-aminophenylphosphonic acid, m-aminophenylphosphonic acid, p-aminophenylphosphonic acid, and those having the following structures. Among these, phenylphosphonic acid, ethylphosphonic acid, n-propylphosphonic acid or n-butylphosphonic acid is preferable, and phenylphosphonic acid is more preferable.

  In the aqueous ink of the present invention, the content of the compound represented by the general formula (2) is 0.01 to 0.25% by mass in the aqueous ink, and preferably 0.05 to 0.2% by mass. 0.1 to 0.2% by mass is more preferable. Within this range, it is possible to obtain a printed material with excellent ink ejection accuracy and good glossiness.

  In the water-based ink of the present invention, only one type of compound represented by the general formula (2) may be used, or a plurality of types may be mixed and used.

<Water-soluble solvent>
The water-based ink of the present invention contains a water-soluble solvent. Examples of the water-soluble solvent include water-soluble organic solvents. Water-soluble organic solvents are used for the purpose of drying inhibitors, wetting agents or penetration enhancers. When the water-based ink is used as an ink-jet ink, an anti-drying agent is used for the purpose of preventing clogging due to drying of the water-based ink (hereinafter also referred to as ink-jet ink) at the ink ejection port of the nozzle. As the agent or wetting agent, a water-soluble organic solvent having a vapor pressure lower than that of water is preferable. In addition, a water-soluble organic solvent is preferably used as a penetration accelerator for the purpose of allowing ink jet ink to penetrate into paper better.

  Examples of water-soluble organic solvents include glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, polyoxyethylene Glyceryl ether, polyoxypropylene glyceryl ether, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1, Alkanediols (polyhydric alcohols) such as 2-hexanediol, 1,2-pentanediol, 4-methyl-1,2-pentanediol; vulcose, mannose, fructose, ribose, xylose, arabino Sugars such as sugar, galactose, aldonic acid, glucitol, (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose; sugar alcohols; peeralonic acids; so-called solid wetting agents such as ureas; ethanol, methanol, C1-C4 alkyl alcohols such as butanol, propanol, isopropanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono -N-propyl ether, ethylene glycol mono-iso-propyl ether, die Lenglycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether , Propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl Glycol ethers such as ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, 1 , 3-dimethyl-2-imidazolidinone, formamide, acetamide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin, sulfolane and the like, and one or more of these can be used.

  Polyol compounds are useful for the purpose of drying inhibitors and wetting agents, such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2 , 3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4- Examples include pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, and the like. These may be used individually by 1 type and may use 2 or more types together.

  For the purpose of the penetrant, a polyol compound is preferable. Examples of the aliphatic diol include 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-hexane Examples include diol, 5-hexene-1,2-diol, and 2-ethyl-1,3-hexanediol. Among these, preferred examples include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.

The water-soluble solvent used in the present invention may be used alone or in combination of two or more. Preferable examples of the water-soluble solvent include glycerin, dipropylene glycol, polyoxyethylene glyceryl ether, and polyoxypropylene glyceryl ether.
The content of the water-soluble organic solvent is 5% by mass to 60% by mass, and preferably 10% by mass to 40% by mass with respect to the total mass of the ink.
The amount of water used in the present invention is not particularly limited, but is preferably 10% by mass or more and 99% by mass or less, more preferably 30% by mass or more and 80% by mass or less with respect to the total mass of the ink. It is. More preferably, it is 50 mass% or more and 70 mass% or less.

<Surfactant>
The ink of the present invention preferably contains a surface tension adjusting agent. Examples of the surface tension adjusting agent include nonionic, cationic, anionic and betaine surfactants. The addition amount of the surface tension adjusting agent is preferably an amount for adjusting the surface tension of the ink of the present invention to 20 to 60 mN / m, more preferably 20 to 45 mN / m, in order to achieve good droplet ejection by inkjet. Preferably, the amount can be adjusted to 25 to 40 mN / m.
As the surfactant in the present invention, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactants, cationic surfactants, amphoteric surfactants can be used. Any of the nonionic surfactants can be used. Furthermore, the above-mentioned polymer substance (polymer dispersing agent) can also be used as a surfactant.

Specific examples of anionic surfactants include, for example, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium stearate, potassium oleate, sodium dioctyl Sulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium dialkylsulfosuccinate, sodium stearate, sodium oleate, t-octylphenoxyethoxypoly Examples include sodium ethoxyethyl sulfate, etc., and select one or more of these Rukoto can.
Specific examples of the nonionic surfactant include, for example, polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene oleyl phenyl ether, polyoxyethylene nonyl phenyl ether, oxyethylene / oxypropylene block copolymer, t- Examples include octylphenoxyethyl polyethoxyethanol, nonylphenoxyethyl polyethoxyethanol, and the like, and one or more of these can be selected.
Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like. Specific examples thereof include dihydroxyethyl stearylamine and 2-heptadecenyl. -Hydroxyethyl imidazoline, lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridium chloride and the like.
Among these surfactants, acetylene-based surfactants are particularly preferable from the viewpoint that ink liquid physical properties such as ink surface tension and viscosity can be suitably adjusted. Specific examples of the acetylene surfactant include Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), and acetylenol E100 (Kawaken Fine Chemical Co., Ltd.). Etc.). By using these acetylene-based surfactants, the landing shape of the ink droplet is stabilized, and the ink is quickly absorbed.
The amount of the surfactant to be added to the inkjet liquid composition in the present invention is not particularly limited, but is preferably 1% by mass or more, more preferably 1 to 10% by mass, and still more preferably 1%. ˜3 mass%.

<Other ingredients>
The ink of the present invention may contain other additives. Other additives include, for example, ultraviolet absorbers, anti-fading agents, anti-mold agents, pH adjusters, rust inhibitors, antioxidants, emulsion stabilizers, preservatives, antifoaming agents, viscosity modifiers, and dispersion stabilizers. Known additives such as agents and chelating agents are included.

  Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, nickel complex salt UV absorbers, and the like.

  As the antifading agent, various organic and metal complex antifading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like.

  Antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one, sodium sorbate, sodium pentachlorophenol, etc. Can be mentioned. These are preferably used in the ink in an amount of 0.02 to 1.00% by mass.

  The pH adjuster is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting the recording ink to be prepared, and can be appropriately selected according to the purpose. Amines (eg, diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol), alkali metal hydroxides (eg, lithium hydroxide, sodium hydroxide, potassium hydroxide), ammonium Examples thereof include hydroxides (for example, ammonium hydroxide and quaternary ammonium hydroxides), phosphonium hydroxides, alkali metal carbonates, and the like.

  Examples of the antirust agent include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, di-propylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like.

  Examples of the antioxidant include phenol antioxidants (including hindered phenol antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like.

  Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate and the like.

<Resin fine particles>
The ink of the present invention may contain fine resin particles or polymer latex. As resin fine particles or polymer latex, acrylic resin, vinyl acetate resin, styrene-butadiene resin, vinyl chloride resin, acrylic-styrene resin, butadiene resin, styrene resin, crosslinked acrylic resin, crosslinked styrene resin Benzoguanamine resin, phenol resin, silicone resin, epoxy resin, urethane resin, paraffin resin, fluorine resin, and the like can be used. Preferred examples include acrylic resins, acrylic-styrene resins, styrene resins, cross-linked acrylic resins, and cross-linked styrene resins.
Preferable examples of the resin fine particles include self-dispersing polymer fine particles. Self-dispersing polymer fine particles are high molecular polymers that can be dispersed in an aqueous medium by the functional groups (particularly acidic groups or salts thereof) of the polymer itself in the absence of other surfactants. , Meaning polymer fine particles containing no free emulsifier. Here, the dispersed state refers to both an emulsified state (emulsion) in which a polymer is dispersed in an aqueous medium in a liquid state and a dispersed state (suspension) in which a polymer is dispersed in a solid state in an aqueous medium. It includes the state of. In the present invention, the polymer is preferably a polymer that can be dispersed in a solid state.
From the viewpoint of self-dispersibility, the self-dispersing polymer fine particles preferably used in the present invention preferably contain a polymer containing a hydrophilic structural unit and a structural unit derived from an aromatic group-containing monomer.

The hydrophilic structural unit is not particularly limited as long as it is derived from a hydrophilic group-containing monomer, and even if it is derived from one kind of hydrophilic group-containing monomer, it contains two or more hydrophilic groups. It may be derived from a monomer. The hydrophilic group is not particularly limited, and may be a dissociable group or a nonionic hydrophilic group. The hydrophilic group is preferably a dissociable group and more preferably an anionic dissociative group from the viewpoint of promoting self-dispersion and the stability of the formed emulsified or dispersed state. Examples of the dissociable group include a carboxyl group, a phosphoric acid group, and a sulfonic acid group. Among them, a carboxyl group is preferable from the viewpoint of fixability when an ink composition is configured. Examples of the dissociable group-containing monomer include an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.
Specific examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid. Specific examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, and bis- (3-sulfopropyl) -itaconate. It is done. Specific examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2- Examples include acryloyloxyethyl phosphate. From the viewpoints of dispersion stability and ejection stability, unsaturated carboxylic acid monomers are preferred, and acrylic acid and methacrylic acid are more preferred.

The aromatic group-containing monomer is not particularly limited as long as it is a compound containing an aromatic group and a polymerizable group. The aromatic group may be a group derived from an aromatic hydrocarbon or a group derived from an aromatic heterocycle. From the viewpoint of particle shape stability in an aqueous medium, an aromatic group derived from an aromatic hydrocarbon is preferable. The polymerizable group may be a condensation polymerizable polymerizable group or an addition polymerizable polymerizable group. In the present invention, from the viewpoint of particle shape stability in an aqueous medium, an addition polymerizable group is preferable, and a group containing an ethylenically unsaturated bond is more preferable.
The aromatic group-containing monomer is preferably a monomer having an aromatic group derived from an aromatic hydrocarbon and an ethylenically unsaturated bond, and more preferably an aromatic group-containing (meth) acrylate monomer. Examples of the aromatic group-containing monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, and a styrene monomer. Among them, from the viewpoint of the balance between the hydrophilicity and hydrophobicity of the polymer chain and the ink fixing property, it is preferably at least one selected from phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and phenyl (meth) acrylate. More preferred is phenoxyethyl (meth) acrylate, and particularly preferred is phenoxyethyl acrylate.

“(Meth) acrylate” means acrylate or methacrylate. The self-dispersing polymer fine particles include a structural unit derived from an aromatic group-containing (meth) acrylate monomer, and the content is preferably 10% by mass to 95% by mass. When the content of the aromatic group-containing (meth) acrylate monomer is 10% by mass to 95% by mass, the stability of the self-emulsification or dispersion state can be improved, and further the increase in ink viscosity can be suppressed. From the viewpoints of stability in a self-dispersing state, stabilization of particle shape in an aqueous medium due to hydrophobic interaction between aromatic rings, and reduction in the amount of water-soluble components due to appropriate hydrophobicity of particles, 15% by mass to 90% by mass. %, More preferably 15% by mass to 80% by mass, and particularly preferably 25% by mass to 70% by mass.
The self-dispersing polymer fine particles can be composed of, for example, a structural unit composed of an aromatic group-containing monomer and a structural unit composed of a dissociable group-containing monomer, but further includes other structural units as necessary. Can be configured.

The monomer that forms the other structural unit is not particularly limited as long as it is a monomer copolymerizable with the aromatic group-containing monomer and the dissociable group-containing monomer. Among these, an alkyl group-containing monomer is preferable from the viewpoint of flexibility of the polymer skeleton and ease of control of the glass transition temperature (Tg).
Examples of the alkyl group-containing monomer include methyl (meth) acrylate, ethyl (meth) acrylate, iso i-propyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) ) Acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate and other alkyl (meth) acrylates; hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl Ethylenically unsaturated monomers having a hydroxyl group such as (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate; Dialkylaminoalkyl (meth) acrylates such as ethyl (meth) acrylate; N-hydroxyalkyl (meth) such as N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-hydroxybutyl (meth) acrylamide Acrylamide; N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N- (n-, iso) butoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-ethoxyethyl (meta And (meth) acrylamides such as N-alkoxyalkyl (meth) acrylamides such as acrylamide and N- (n-, iso) butoxyethyl (meth) acrylamide.
The molecular weight range of the polymer constituting the self-dispersing polymer fine particles in the present invention is preferably 3000 to 200,000, more preferably 5,000 to 150,000, and more preferably 10,000 to 100,000 in terms of mass average molecular weight. More preferably it is. By setting the mass average molecular weight to 3000 or more, the amount of water-soluble components can be effectively suppressed. Moreover, self-dispersion stability can be improved by making a mass average molecular weight into 200,000 or less.

The mass average molecular weight can be measured by gel permeation chromatography (GPC).
From the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer, the polymer polymer constituting the self-dispersing polymer fine particles contains 15 to 90% by mass of an aromatic group-containing (meth) acrylate monomer as a copolymerization ratio, a carboxyl group-containing monomer and an alkyl group. A monomer having an acid value of 25 to 100 and a mass average molecular weight of preferably 3000 to 200,000, and an aromatic group-containing (meth) acrylate monomer as a copolymerization ratio of 15 to 80% by mass and carboxyl More preferably, it contains a group-containing monomer and an alkyl group-containing monomer, has an acid value of 25 to 95, and a mass average molecular weight of 5,000 to 150,000.
The average particle size of the self-dispersing polymer fine particles is preferably in the range of 10 nm to 1 μm, more preferably in the range of 10 to 200 nm, still more preferably in the range of 20 to 100 nm, and particularly preferably in the range of 20 to 50 nm.
The addition amount of the self-dispersing polymer fine particles is preferably 0.5 to 20% by mass, more preferably 3 to 20% by mass, and still more preferably 5 to 15% by mass with respect to the ink.
The glass transition temperature Tg of the self-dispersing polymer fine particles is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 50 ° C. or higher. Moreover, there is no restriction | limiting in particular regarding the particle size distribution of a polymer particle, What has a wide particle size distribution or a thing with a monodispersed particle size distribution may be sufficient. Further, two or more kinds of polymer fine particles having a monodispersed particle size distribution may be mixed and used.

<Liquid composition for improving printability>
In the present invention, it is preferable to apply a liquid composition for improving printability to a print medium.
A preferred example of the liquid composition that can be used in the present invention to improve the printability is a liquid composition that generates an aggregate by changing the pH of the ink. At this time, the pH of the liquid composition is preferably 1 to 6, more preferably 2 to 5, and still more preferably 3 to 5. As components of the liquid composition, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid, It is preferably selected from pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof. . These compounds may be used alone or in combination of two or more.

  A preferred example of a liquid composition that can be used in the present invention to improve printability is a treatment liquid to which a polyvalent metal salt or polyallylamine is added. As a component of the liquid composition, as a polyvalent metal salt, an alkaline earth metal of Group 2A of the periodic table (for example, magnesium and calcium); a transition metal of Group 3B of the periodic table (for example, lanthanum); from Group 3A of the periodic table Cations (for example, aluminum); lanthanides (for example, neodymium); and polyallylamine and polyallylamine derivatives. Preferred examples include calcium and magnesium. Anions that are preferably employed as a counter salt of calcium or magnesium include carboxylate (formic acid, acetic acid, benzoate, etc.), nitrate, chloride, and thiocyanate. The amount of the salt added to the treatment liquid is about 1 to about 10% by weight, preferably about 1.5 to about 7% by weight, more preferably about 2 to about 6% by weight in the treatment liquid. Can exist.

<Ink physical properties>
The surface tension of the ink of the present invention is preferably 20 mN / m or more and 60 mN / m or less. More preferably, it is 20 mN or more and 45 mN / m or less, More preferably, it is 25 mN / m or more and 40 mN / m or less.
The viscosity of the ink of the present invention at 20 ° C. is preferably 1.2 mPa · s or more and 15.0 mPa · s or less, more preferably 2 mPa · s or more and less than 13 mPa · s, and further preferably 2.5 mPa · s. This is less than 10 mPa · s.

<Inkjet recording method>
As a preferred ink jet recording method for the present invention, a known image receiving material such as plain paper, resin-coated paper, for example, JP-A-8-169172, JP-A-8-27693, JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783, JP-A-10-153989, JP-A-10-217473, JP-A-10-235995 10-337947, 10-217597, 10-337947, etc. Form images on inkjet paper, film, electrophotographic co-paper, fabric, glass, metal, ceramics, etc. To do. In addition, the description of paragraph numbers 0093 to 0105 in JP-A No. 2003-306623 can be applied as an ink jet recording method preferable for the present invention.
In particular, the water-based ink of the present invention is preferably used for thermal ink jet recording in order to sufficiently exhibit the effects of the present invention.

  In forming an image, a polymer latex compound may be used in combination for the purpose of imparting glossiness or water resistance or improving weather resistance. The timing of applying the latex compound to the image receiving material may be before, after, or simultaneously with the application of the colorant, and therefore the addition location may be in the image receiving paper. It may be in ink or may be used as a liquid material of polymer latex alone. Specifically, JP 2002-166638 (Japanese Patent Application 2000-363090), JP 2002-121440 (Japanese Patent Application 2000-315231), JP 2002-154201 (Japanese Patent Application 2000-354380), JP 2002-144696 ( The methods described in Japanese Patent Application No. 2000-343944) and Japanese Patent Application Laid-Open No. 2002-080759 (Japanese Patent Application No. 2000-268952) can be preferably used.

As an example of a preferred image forming method for the present invention,
1st process: The process of providing the liquid composition which improves printability to a recording medium.
Second step: a step of applying an ink composition to the recording medium to which the liquid composition has been applied.
Other steps: Other steps are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a drying removal step and a heat fixing step. The drying removal step is not particularly limited except that the ink solvent in the ink composition applied to the recording medium is removed by drying, and can be appropriately selected according to the purpose. The heat fixing step is not particularly limited except that the latex particles contained in the ink used in the ink jet recording method are melt-fixed, and can be appropriately selected depending on the purpose.

As another example of an image forming system preferable for the present invention,
1st process: The process of providing the liquid composition which improves printability to an intermediate transfer body.
Second step: a step of applying an ink composition to the intermediate transfer body to which the liquid composition has been applied.
Third step: a step of transferring an ink image formed on the intermediate transfer member to a recording medium.
Other steps: Other steps are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a drying removal step and a heat fixing step.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples at all. In the examples, “parts” represents parts by mass.
The azo pigments of the present invention are described in Pig. It is possible to synthesize according to the synthesis method of -1.

[Synthesis Example 1]
(Synthesis of pigment)
Synthesis of Exemplary Compound (Pig.-1) A synthesis scheme of exemplary compound (Pig.-1) is shown below.

(1) Synthesis of intermediate (a) 29.7 g (0.3 mol) of methyl cyanoacetate, 42.4 g (0.4 mol) of trimethyl orthoformate, 20.4 g (0.2 mol) of acetic anhydride, p- Toluenesulfonic acid 0.5 g was added and heated to 110 ° C. (external temperature), and the mixture was stirred for 20 hours while distilling off low-boiling components generated from the reaction system. The reaction solution was concentrated under reduced pressure, and then purified on a silica gel column to obtain 14.1 g of the intermediate (a) (yellow powder, yield 30%). The NMR measurement result of the obtained intermediate (a) is as follows.
¹ H-NMR (300 MHz, CDCl ₃ ) 7.96 (s, 1H), 4.15 (s, 3H), 3.81 (s, 3H)

(2) Synthesis of Intermediate (b) 150 mL of isopropanol was added to 7.4 mL (141 mmol) of methyl hydrazine and cooled to 15 ° C. (internal temperature), and 7.0 g (49. 6 mmol) was gradually added, and the mixture was heated to 50 ° C. and stirred for 1 hour and 40 minutes. The reaction solution was concentrated under reduced pressure, and then purified on a silica gel column to obtain 10.5 g of the intermediate (b) (white powder, yield 50%). The NMR measurement result of the obtained intermediate (b) is as follows.
¹ H-NMR (300 MHz, CDCl ₃ ) 7.60 (s, 1H), 4.95 (brs, 2H), 3.80 (s, 3H) 3.60 (s, 3H)

(3) Synthesis of Intermediate (c) 100 mL of methanol was added to 130 mL of hydrazine monohydrate and cooled to 10 ° C. (internal temperature), and 50.0 g (336 mmol) of 4,6-dichloropyrimidine was added to this mixture. After gradually adding (internal temperature 20 ° C. or less), the mixture was heated to 50 ° C. and stirred for 4 hours 30 minutes. Crystals precipitated from the reaction solution were collected by filtration, washed with isopropanol, and dried to obtain 43.1 g of the intermediate (c) (white powder, yield 92%). The NMR measurement result of the obtained intermediate (c) is as follows.
¹ H-NMR (300 MHz, d-DMSO) 7.82 (s, 1H), 7.55 (s, 2H), 5.96 (s, 1H), 4.12 (s, 4H)

(4) Synthesis of intermediate (d) 900 mL of water was added to 35.0 g (0.25 mol) of intermediate (c) and 68.8 g (0.55 mol) of pivaloyl acetonitrile, and the mixture was stirred at room temperature. To this suspension, 1M aqueous hydrochloric acid was added dropwise so as to have a pH of 3, and the mixture was heated to 50 ° C. and stirred for 8 hours. To this reaction solution, 8M aqueous potassium hydroxide solution is added dropwise to adjust the pH to 8. Further, 1M hydrochloric acid solution is added dropwise to adjust to pH 6, and the precipitated crystals are collected by filtration, washed with isopropanol, dried, and dried. 83.0 g (white powder, 94% yield) of (d) was obtained. The NMR measurement result of the obtained intermediate (d) is as follows.
¹ H-NMR (300 MHz, d-DMSO) 8.73 (s, 1H), 7.97 (s, 1H), 6.88 (s, 4H), 5.35 (s, 2H), 1.22 (S, 18H)

(5) Synthesis of Exemplary Compound (Pig.-1) Acetic acid (18.5 mL) was added to concentrated sulfuric acid (4.1 mL), and the mixture was stirred with ice cooling, and 40% nitrosylsulfuric acid (3.85 g, 12.1 mmol) was added dropwise. Intermediate (b) 1.71 g (11.0 mmol) was gradually added to this mixture (internal temperature of 0 ° C. or lower), and the mixture was stirred at 0 ° C. for 2 hours. 150 mg of urea was added to the reaction solution, and the mixture was further stirred at 0 ° C. for 15 minutes to prepare a diazo solution A.
50 mL of methanol was added to the intermediate (d) and dissolved by heating, and then the diazo solution A was slowly added dropwise to an ice-cooled mixture (internal temperature of 10 ° C. or lower). After the reaction solution was stirred at room temperature for 2 hours, the precipitated crystals were collected by filtration and washed with methanol to obtain crude crystals of the exemplified compound (Pig.-1). Further, after adding water to the crude crystals and stirring, the suspension was adjusted to pH 7 with an aqueous sodium hydroxide solution, and further 20 mL of dimethylacetamide was added and stirred at 80 ° C. for 2 hours. The precipitated crystals were collected by filtration and suspended and washed with methanol. The obtained crystals were collected by filtration and dried to obtain 2.0 g (yellow powder, yield 79%) of the exemplified compound (Pig.-1).

[Synthesis Example 2]
(Synthesis of pigment)
(Synthesis of Exemplary Compound (Pig.-18))
A synthesis scheme of the exemplified compound (Pig.-18) is shown below.

(1) Synthesis of intermediate (a) 29.7 g (0.3 mol) of methyl cyanoacetate, 42.4 g (0.4 mol) of trimethyl orthoformate, 20.4 g (0.2 mol) of acetic anhydride, p- Toluenesulfonic acid 0.5 g was added and heated to 110 ° C. (external temperature), and the mixture was stirred for 20 hours while distilling off low-boiling components generated from the reaction system. The reaction solution was concentrated under reduced pressure, and then purified on a silica gel column to obtain 14.1 g of the intermediate (a) (yellow powder, yield 30%). The NMR measurement result of the obtained intermediate (a) is as follows.
¹ H-NMR (300 MHz, CDCl ₃ ) 7.96 (s, 1H), 4.15 (s, 3H), 3.81 (s, 3H)

(2) Synthesis of Intermediate (b) 150 mL of isopropanol was added to 7.4 mL (141 mmol) of methyl hydrazine and cooled to 15 ° C. (internal temperature), and 7.0 g (49. 6 mmol) was gradually added, and the mixture was heated to 50 ° C. and stirred for 1 hour and 40 minutes. The reaction solution was concentrated under reduced pressure, and then purified on a silica gel column to obtain 10.5 g of the intermediate (b) (white powder, yield 50%). The NMR measurement result of the obtained intermediate (b) is as follows.
¹ H-NMR (300 MHz, CDCl ₃ ) 7.60 (s, 1H), 4.95 (brs, 2H), 3.80 (s, 3H), 3.60 (s, 3H)

(3) Synthesis of intermediate (c ′) 136 mL of water was added to 1.1 L of methanol, 182 g (2.17 mol) of sodium bicarbonate was added, and the mixture was stirred at room temperature. At the same temperature, 200 g (1.08 mol) of cyanuric chloride was added in portions. After the addition, the internal temperature was raised to 30 ° C. After stirring at the same temperature for 30 minutes, 500 mL of water was added, the precipitated solid was filtered, washed with 500 mL of water and 300 mL of methanol, dried, and 168 g of the intermediate (c ′) (white powder, collected). 86.2%). The NMR measurement result of the obtained intermediate (c ′) is as follows.
¹ H-NMR (300 MHz, CDCl ₃ ) 4.14 (s, 3H)

(4) Synthesis of intermediate (d ′) 673 mL of water was added to 363 mL (7.46 mol) of hydrazine monohydrate and cooled to 10 ° C. (internal temperature), and 168 g of intermediate (c ′) was added to this mixture. (934 mmol) was gradually added (internal temperature 20 ° C. or lower), the ice bath was removed, the temperature was raised to room temperature, and the mixture was stirred at the same temperature for 30 minutes. Crystals precipitated from the reaction solution were collected by filtration, washed with 700 mL of water and 1 L of acetonitrile, and dried to obtain a loosely purified product (white powder) of the intermediate (d ′).

(5) Synthesis of Intermediate (e) 480 mL of ethylene glycol was added to the loosely purified product of Intermediate (d ′) and stirred at room temperature. To this suspension, 257 g (2.06 mol) of pivaloyl acetonitrile was added and heated until the internal temperature reached 50 ° C. After dropwise addition of 12M aqueous hydrochloric acid at the same temperature to pH 3, the mixture was heated to an internal temperature of 80 ° C. and stirred for 3 hours. After completion of the reaction, the mixture was ice-cooled and cooled to an internal temperature of 8 ° C. The precipitated crystals were collected by filtration, washed with water, and purified by silica gel column. 105g of the intermediate (e) (white powder, 2 steps) (Yield 29.2%). The NMR measurement result of the obtained intermediate (e) is as follows.
¹ H-NMR (300 MHz, d-DMSO) 7.00 (s, 4H), 5.35 (s, 2H), 4.05 (s, 3H), 5.35 (s, 2H), 1.22 (S, 18H)

(6) Synthesis of Exemplary Compound (Pig.-18) A mixture of 125 mL of acetic acid and 24 mL of sulfuric acid was ice-cooled, and the internal temperature was cooled to 3 ° C. At the same temperature, 26.4 g of nitrosylsulfuric acid was added, and subsequently, 11.6 g of intermediate (b) was dividedly added and dissolved at the same temperature. After stirring for 1 hour at the same temperature, 1.2 g of urea was added in portions at the same temperature and stirred for 15 minutes at the same temperature to obtain a diazonium salt solution. Separately, 11.6 g of intermediate (e) was completely dissolved in 405 mL of methanol at room temperature, and ice-cooled to cool the internal temperature to -3 ° C. At the same temperature, the above-described diazonium salt solution was added in portions so that the internal temperature was 3 ° C. or less, and stirred for 2 hours after the addition was completed. After removing the ice bath and stirring at room temperature for 10 minutes, the precipitated crystals were separated by filtration, washed with 150 mL of methanol, and further washed with 100 mL of water. The obtained crystals were suspended in 750 mL of water without drying, and 8N aqueous potassium hydroxide solution was added to adjust the pH to 5.7. After stirring at room temperature for 20 minutes, the obtained crystals were separated by filtration, thoroughly washed with water, and then washed with 80 mL of methanol. The obtained crystals were dried at room temperature for 12 hours to obtain 20.3 g of exemplary compound (Pig.-18). Yield 94.0%

[Synthesis Example 3]
(Synthesis of vinyl polymer (P-1))
(Synthesis of vinyl polymer)
Components of the following monomer composition are mixed so that the total amount becomes 100 parts by mass, and further 1 part by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) is added as a polymerization initiator, and nitrogen gas replacement is sufficiently performed. And a synthesis mixture was obtained.

Phenoxyethyl methacrylate 55 parts by weight Methyl methacrylate 35 parts by weight Methacrylic acid 10 parts by weight 2-Mercaptoethanol 0.1 part by weight

  Next, 100 parts by mass of methyl ethyl ketone was heated to 75 ° C. with stirring in a nitrogen atmosphere. The synthetic mixture was added dropwise over 3 hours at 75 ° C. with stirring. The reaction was further continued at 75 ° C. with stirring for 5 hours. Thereafter, the reaction product was naturally cooled to 25 ° C. and then diluted by adding methyl ethyl ketone so that the solid content was 50% to obtain a vinyl polymer solution having a mass average molecular weight of 41,000.

[Synthesis Example 4]
(Synthesis of vinyl polymer (P-2))
In the synthesis of the vinyl polymer (P-1), a vinyl polymer (P-2) was synthesized in the same manner except that the components of the monomer composition were changed to the following compositions. The mass average molecular weight was 36000.

Phenoxyethyl methacrylate 52 parts by weight Methyl methacrylate 33 parts by weight Methacrylic acid 15 parts by weight 2-Mercaptoethanol 0.1 part by weight

[Example 1]
(Solvent Salt Milling Treatment of Exemplary Compound Pig.-18)
The crude azo pigment and sodium chloride were added to a supermixer and mixed so as to have the following composition. While rotating the super mixer, diethylene glycol was added little by little, and Pig. A mixture of -18 (hereinafter sometimes referred to as "preliminary mixture") was prepared.
<Composition of refined yellow pigment (Pig-Y18)>
Illustrative compound (Pig.-18) 100 parts by weight Sodium chloride (Nakuru UM-5, manufactured by Naikai Shigyo Co., Ltd., particle size 5 μm) 1500 parts by weight Diethylene glycol (DEG) 300 parts by weight

Subsequently, the temperature of the 5 parts of the grinding part and the extrusion part of the continuous uniaxial kneading machine (Miracle KCK-L, manufactured by Asada Tekko Co., Ltd.) is set to 15 to 20 ° C. and the shaft rotation speed is set to 40 rpm. The preliminary mixture obtained in (1) was added to obtain a kneaded product. At this time, the current value (load) was about 5 A, the discharge rate was 45 g / min, and the temperature of the discharge was 17 ° C.
After 1,000 parts by mass of the kneaded material thus obtained were put into 5,000 parts by mass of pure water heated to 80 ° C. and stirred using a clear mix, the sample was filtered and washed thoroughly with water. And diethylene glycol was removed, and a wet cake (Pig-Y18, azo pigment ground product) of a fine yellow pigment prepared so that the solid content was 25% by mass was obtained.
(Preparation of aqueous dispersion (1) of 15% by mass pigment-containing vinyl polymer particles)
Using the wet cake (Pig-Y18, azo pigment ground product) of the refined yellow pigment after the above solvent salt milling treatment, the mixture is mixed so as to have the following composition, and Claremix (manufactured by MTECHNIQUE; CLM-0.8S). , 15000 rpm) for 15 minutes, and further subjected to a 3-pass dispersion treatment with a high-pressure homogenizer (manufactured by Mizuho Kogyo Co., Ltd .; Microfluidizer M-140K, 150 MPa). Subsequently, methyl ethyl ketone was removed from the obtained dispersion under reduced pressure at 56 ° C., ion-exchanged water was added, and the pigment-containing vinyl polymer particles were adjusted so that the concentration of the exemplary compound (Pig.-18) was 15.0% by mass. An aqueous dispersion was prepared.
With respect to the aqueous dispersion (1) of the obtained pigment-containing vinyl polymer particles, the average particle size was measured by a dynamic light scattering method using a nanotrack particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.). The measurement is performed by adding 10 ml of ion exchange water to 30 μl of an aqueous dispersion of pigment-containing vinyl polymer particles to prepare a sample solution for measurement, and adjusting the temperature to 25 ° C., and the volume average particle size Mv is 84 nm. there were.
The obtained aqueous dispersion (1) of pigment-containing vinyl polymer particles was measured using a R100 viscometer (manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25 ° C. and cone rotation speed of 100 rpm, and the viscosity was 2.4 mPas. Met.
It was 9.1 when the water dispersion (1) of the obtained pigment containing vinyl polymer particle | grains was measured at 25 degreeC using Toa DKK Co., Ltd. pH meter-WM-50EG.

<Composition of aqueous dispersion (1) of pigment-containing vinyl polymer particles>
Azo pigment ground product (Pig.-Y18) 60.0 parts by weight Vinyl polymer (P-1) 4.5 parts by weight Methyl ethyl ketone 9.4 parts by weight 1 mol / L NaOH aqueous solution 5.5 parts by weight Ion-exchanged water 20.6 parts by weight Part

(Preparation of water-based ink composition (1) for inkjet recording)
Next, an aqueous ink composition (1) having the following composition was prepared using the obtained aqueous dispersion (1) of pigment-containing vinyl polymer particles. The pH of the water-based ink composition (1) was measured at 25 ° C. with a pH meter-WM-50EG manufactured by Toa DKK Co., Ltd. and found to be 7.6.

(Composition of water-based ink composition (1))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenyl Phosphonic acid 0.1 parts by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Example 2]
A water-based ink composition (2) was prepared with the composition shown below. When the pH of the water-based ink composition (2) was measured at 25 ° C. in the same manner as in Example 1, it was 7.8.

(Composition of water-based ink composition (2))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass ethyl Phosphonic acid 0.1 parts by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Example 3]
A water-based ink composition (3) was prepared with the composition shown below. When the pH of the water-based ink composition (3) was measured at 25 ° C. in the same manner as in Example 1, it was 8.7.
(Composition of water-based ink composition (3))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-pyrrolidone 4 parts by mass Triethanolamine 1 part by mass Olphine E1010 (Nisshin Chemical Industry Co., Ltd.) Product) 1 part by mass Compound (A) 0.1 part by mass Ion-exchanged water The remainder (amount that the total of the composition is 100 parts by mass)

  In addition, a compound (A) points out the compound of the following structures.

[Example 4]
A water-based ink composition (4) was prepared with the composition shown below. When the pH of the water-based ink composition (4) was measured at 25 ° C. in the same manner as in Example 1, it was 7.7.

(Composition of water-based ink composition (4))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass Glycerin 8 parts by mass Ethylene glycol 8 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenylphosphonic acid 0.1 part by mass Ion-exchanged water Remainder (amount that totals 100 parts by mass)

[Example 5]
A water-based ink composition (5) was prepared with the composition shown below. When the pH of the water-based ink composition (5) was measured at 25 ° C. in the same manner as in Example 1, it was 7.7.

(Composition of water-based ink composition (5))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass Glycerin 8 parts by mass Ethylene glycol 8 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Ethylphosphonic acid 0.1 part by mass Ion-exchanged water Remainder (amount that totals 100 parts by mass of composition)

[Example 6]
A water-based ink composition (6) was prepared with the composition shown below. When the pH of the water-based ink composition (6) was measured at 25 ° C. in the same manner as in Example 1, it was 7.8.

(Composition of water-based ink composition (6))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass Glycerin 8 parts by mass Diethylene glycol 4 parts by mass Isopropyl alcohol 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenylphosphonic acid 0.1 mass Part Ion-exchanged water The remainder (amount that the total of the composition is 100 parts by mass)

[Example 7]
A water-based ink composition (7) was prepared with the composition shown below. When the pH of the water-based ink composition (7) was measured at 25 ° C. in the same manner as in Example 1, it was 7.7.

(Composition of water-based ink composition (7))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass Glycerin 10 parts by mass Triethylene glycol 4 parts by mass PEG (300) 2 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenylphosphonic acid 0.1 part by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Example 8]
A water-based ink composition (8) was prepared with the composition shown below. When the pH of the water-based ink composition (8) was measured at 25 ° C. in the same manner as in Example 1, it was 8.9.

(Composition of water-based ink composition (8))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass Glycerol 8 parts by mass 2-Pyrrolidone 4 parts by mass 1,2-hexanediol 4 parts by mass Triethanolamine 1 part by mass Olphine E1010 (Nisshin Chemical Industry Co., Ltd.) Manufactured) 1 part by weight phenylphosphonic acid 0.1 part by weight ion-exchanged water remaining part (amount that the total of the composition is 100 parts by weight)

[Example 9]
(Preparation of aqueous dispersion (2) of 15% by mass pigment-containing vinyl polymer particles)
The wet cake (Pig-Y18, azo pigment ground product) of the refined yellow pigment after the solvent salt milling treatment of Example 1 was used and mixed so as to have the following composition, and 0.1 mmφ zirconia beads were used in a bead mill. Dispersed for 6 hours. Subsequently, methyl ethyl ketone was removed from the obtained dispersion under reduced pressure at 56 ° C., ion-exchanged water was added, and the pigment-containing vinyl polymer particles were adjusted so that the concentration of the exemplary compound (Pig.-18) was 15.0% by mass. An aqueous dispersion was prepared. It was 8.7 when the water dispersion (2) of the obtained pigment containing vinyl polymer particle | grains was measured at 25 degreeC using pH meter WM-50EG by Toa DKK Co., Ltd. product.

<Composition of pigment-containing vinyl polymer aqueous dispersion (2)>
Azo pigment ground product (Pig.-Y18): 60.0 parts by mass Vinyl polymer (P-1): 4.5 parts by mass Methyl ethyl ketone: 9.4 parts by mass 1 mol / L NaOH aqueous solution: 5.5 parts by mass Ion-exchanged water : 20.6 parts by mass

  Next, an aqueous ink composition (9) was prepared with the composition shown below using the obtained aqueous dispersion (2) of pigment-containing vinyl polymer particles. The pH of the water-based ink composition (9) was measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd. and found to be 7.7.

(Composition of water-based ink composition (9))
Aqueous dispersion of pigment-containing vinyl polymer particles (2) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenyl Phosphonic acid 0.1 parts by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Example 10]
A water-based ink composition (10) was prepared with the composition shown below. When the pH of the aqueous ink composition (10) was measured at 25 ° C. in the same manner as in Example 1, it was 8.0.

(Composition of water-based ink composition (10))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenyl Phosphonic acid 0.05 parts by mass Ion-exchanged water The remainder (amount that the total of the composition is 100 parts by mass)

[Example 11]
In the same manner as in the preparation of the aqueous dispersion (1) of 15% by mass of pigment-containing vinyl polymer particles in Example 1, an aqueous dispersion (3) of pigment-containing vinyl polymer particles having the following composition was prepared. It was 8.8 when the water dispersion (3) of the obtained pigment containing vinyl polymer particle | grains was measured at 25 degreeC using pH meter WM-50EG by Toa DKK Co., Ltd. product.

(Composition of aqueous dispersion (3) of pigment-containing vinyl polymer particles)
Illustrative compound (Pig.-1) 15.0 parts by weight Vinyl polymer (P-1) 4.5 parts by weight Methyl ethyl ketone 9.4 parts by weight 1 mol / L NaOH aqueous solution 5.5 parts by weight Ion-exchanged water 65.6 parts by weight

  Next, an aqueous ink composition (11) having the following composition was prepared using the obtained aqueous dispersion (3) of pigment-containing vinyl polymer particles. The pH of the water-based ink composition (11) was measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd. and found to be 7.7.

(Composition of water-based ink composition (11))
Aqueous dispersion of pigment-containing vinyl polymer particles (3) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenyl Phosphonic acid 0.1 parts by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Example 12]
In the same manner as in the preparation of the aqueous dispersion (1) of 15% by mass of pigment-containing vinyl polymer particles in Example 1, an aqueous dispersion (4) of pigment-containing vinyl polymer particles having the following composition was produced. It was 8.6 when the water dispersion (4) of the obtained pigment containing vinyl polymer particle | grains was measured at 25 degreeC using pH meter WM-50EG by Toa DKK Co., Ltd. product.

(Composition of aqueous dispersion (4) of pigment-containing vinyl polymer particles)
Illustrative compound (Pig.-18) 15.0 parts by weight Vinyl polymer (P-2) 4.5 parts by weight Methyl ethyl ketone 9.4 parts by weight 1 mol / L NaOH aqueous solution 5.5 parts by weight Ion-exchanged water 65.6 parts by weight

  Next, using the obtained aqueous dispersion (4) of the pigment-containing vinyl polymer particles, an aqueous ink composition (12) was prepared with the following composition. The pH of the aqueous ink composition (12) was measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd. and found to be 7.4.

(Composition of water-based ink composition (12))
Aqueous dispersion of pigment-containing vinyl polymer particles (4) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-Pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenyl Phosphonic acid 0.1 parts by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Example 13]
(Preparation of aqueous dispersion (5) of 15% by mass pigment-containing vinyl polymer particles)
In the preparation of the aqueous dispersion (2) of the pigment-containing vinyl polymer particles of Example 9, the exemplified compound Pig. Not subjected to the solvent salt milling treatment was used. An aqueous dispersion (5) of pigment-containing vinyl polymer particles was prepared in the same manner as in Example 9 except that -18 was used so that the concentration of the exemplified compound (Pig.-18) was 15.0% by mass.

  Next, using the obtained aqueous dispersion (5) of the pigment-containing vinyl polymer particles, an aqueous ink composition (13) was prepared with the following composition. The pH of the water-based ink composition (13) was measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd. and found to be 7.7.

(Composition of water-based ink composition (13))
Aqueous dispersion of pigment-containing vinyl polymer particles (5) 35 parts by mass 1,2-hexanediol 5 parts by mass Glycerin 10 parts by mass 2-pyrrolidone 5 parts by mass Triethanolamine 0.5 part by mass Olphine E1010 (Nisshin Chemical Industry ( 1 part by weight phenylphosphonic acid 0.1 part by weight ion-exchanged water remaining part (amount that the total of the composition is 100 parts by weight)

[Comparative Example 1]
As a pigment, C.I. I. Pigment Yellow 74 pigment was used to synthesize a vinyl polymer according to the synthesis examples described in paragraphs [0053] to [0059] of JP-A No. 2000-239594, and a pigment-containing dispersion was prepared. According to the method 1, an aqueous ink composition (14) containing the following was prepared. The pH of the aqueous ink composition (14) was measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd., and found to be 8.7.

(Composition of water-based ink composition (14))
Pigment-containing dispersion (pigment concentration 15% by mass) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-Pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass phenylphosphone Acid 0.1 part by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Comparative Example 2]
Using the pigment exemplified compound (Pig.-18) of the present invention as the pigment and using Disperbyk187 (produced by Big Chemie Japan Co., Ltd., water-soluble polymer dispersant (polyfunctional polymer)) as the vinyl polymer, a dispersion was prepared. According to the method of Example 1 of the present invention, an aqueous ink composition (15) containing the following was prepared. The pH of the water-based ink composition (15) was measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd., and found to be 8.4. Disperbyk 187 does not correspond to the B component according to the present invention.

(Composition of water-based ink composition (15))
Pigment-containing dispersion (pigment concentration 15% by mass) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-Pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass phenylphosphone Acid 0.1 part by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

[Comparative Example 3]
A water-based ink composition (16) was prepared according to the method of Example 1 with the following composition. The pH of the water-based ink composition (16) measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd. was 8.5.

(Composition of water-based ink composition (16))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass Glycerin 8 parts by mass Diethylene glycol 4 parts by mass Isopropyl alcohol 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Ion-exchanged water remainder (composition) Of the total amount of 100 parts by mass)

[Comparative Example 4]
A water-based ink composition (17) was prepared according to the method of Example 1 with the following composition. The pH of the water-based ink composition (17) was measured at 25 ° C. with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd., and found to be 6.4.

(Composition of water-based ink composition (17))
Aqueous dispersion of pigment-containing vinyl polymer particles (1) 35 parts by mass 1,2-hexanediol 4 parts by mass Glycerin 8 parts by mass 2-pyrrolidone 4 parts by mass Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass Phenyl Phosphonic acid 0.4 parts by mass Ion-exchanged water The remaining part (amount that the total of the composition is 100 parts by mass)

  The pigment concentration in each of the aqueous ink compositions (1) to (17) was 5% by mass.

(Discharge accuracy evaluation)
About the produced water-based ink compositions (1) to (17), using an inkjet printer BJ-F850 (manufactured by Canon Inc.) as an inkjet recording apparatus, a solid and ruled line in a 30 ° C. environment in which a yellow single-color solid image was printed The pattern was printed continuously. A nozzle check was performed before continuous printing, and evaluation was started after confirming the filling properties. Xerox 4024 manufactured by Fuji Xerox Co., Ltd. was used as a recording medium. When there was a disorder due to missing dots or ink splattering or bending during printing, cleaning was performed each time as a recovery operation. As a result, the number of cleanings required for 100 pages of continuous printing in A4 size was evaluated and evaluated according to the following criteria. The evaluation results are shown in Table 1.

<Evaluation criteria>
A: Zero cleaning times.
B: Number of cleanings 1 to 3 times.
C: Number of cleanings 4 times or more.

(Glossiness)
A yellow single-color solid image was printed using the prepared pigment ink composition. As a recording medium, Fuji Photo Film Co., Ltd. picture-finishing photo finishing Pro was used. For each of the yellow monochromatic solid image portions, an image with an optical density of around 1.0 was obtained using a digital variable photometer (trade name: UGV-5D, manufactured by Suga Test Instruments Co., Ltd.) according to JIS Z8741 (1997). The glossiness at an incident angle of 45 ° and a light receiving angle of 45 ° was measured and evaluated according to the following criteria.
<Evaluation criteria>
A: 45 ° glossiness is 70% or more.
B: 45 ° glossiness is less than 70%.

(Glossiness change)
The prepared pigment ink composition was put in a PET container, sealed, and stored in a thermostatic bath at 65 ° C. for 21 days, and a Dmax yellow single-color solid image was printed using the pigment ink composition before and after storage. As a recording medium, Fuji Photo Film Co., Ltd. picture-finishing photo finishing Pro was used. For each of the yellow solid color solid image portions, according to JIS Z8741 (1997), a digital variable angle photometer (trade name: UGV-5D, manufactured by Suga Test Instruments Co., Ltd.) was used. The glossiness was measured and evaluated according to the following criteria.

<Evaluation criteria>
A: 45 ° glossiness is less than ± 5% of the value before storage.
B: 45 ° glossiness is -5% to less than -10% of the value before storage.
C: 45 ° glossiness is -10% or less of the value before storage.

Claims (12)

A water-based ink containing a colorant containing the following A and B and the following C, wherein the content of C is 0.05% by mass or more and 0.25% by mass or less.
A: An azo pigment represented by the following general formula (1), a tautomer thereof, a salt or a hydrate thereof B: a hydrophobic structural unit (a) represented by the following general formula (PI) And a vinyl polymer containing a hydrophilic structural unit (b) C: a compound represented by the following general formula (2).

(In General Formula (1), Z represents a 5-6 membered heterocyclic ring, Y < ₁ >, Y < ₂ >, R < ₁₁ >, R < ₁₂ > represents a hydrogen atom or a substituent each independently, G < ₁ >, G < ₂ > is Each independently represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group or an aryl group. )

(In General Formula (PI), R ₁ represents a hydrogen atom, a methyl group, or a halogen atom, and L ₁ represents —COO—, —OCO—, —CONR ₂ —, —O—, or substituted or unsubstituted. R ₂ represents a hydrogen atom or an alkyl group, L ₂ represents a single bond or a divalent linking group, and Ar ₁ represents a monovalent group derived from an aromatic ring.)

(In general formula (2), R represents the following 1) or 2).
1) unsubstituted or alkyl group substituted by hydroxyl group, amino group, nitro group or carboxyl group,
2) A phenyl group which is unsubstituted or substituted with an amino group, an alkyl group or a hydroxyl group. )   2. The water-based ink according to claim 1, wherein R in the general formula (2) is a substituted or unsubstituted alkyl group substituted with a carboxyl group or a phenyl group.   The water-based ink according to claim 1 or 2, wherein the vinyl polymer further comprises a hydrophobic structural unit (a2) derived from an alkyl ester of acrylic acid or methacrylic acid.   At least one selected from the structural unit derived from phenoxyethyl (meth) acrylate and the structural unit derived from benzyl (meth) acrylate as the hydrophobic structural unit (a) is 20 masses in total with respect to the total mass of the vinyl polymer. %, And the hydrophilic structural unit (b) contains at least one selected from structural units derived from acrylic acid and methacrylic acid in a total amount of 30% by mass or less based on the total mass of the vinyl polymer. The water-based ink according to any one of claims 1 to 3.   The hydrophobic structural unit (a) contains at least 20% by mass of structural units derived from phenoxyethyl (meth) acrylate, based on the total mass of the vinyl polymer. The water-based ink according to item. In general formula (1), W ₁ and W ₂ are each independently an alkoxy group having 1 to 3 carbon atoms, an amino group, or an alkylamino group having 1 to 3 carbon atoms. The water-based ink according to any one of 1 to 5. In the general formula (1), G ₁ and G ₂ are each independently an alkyl group having 1 to 3 carbon atoms, and the water-based ink according to any one of claims 1 to 6.   In general formula (1), Z is a 6-membered nitrogen-containing heterocycle, The water-based ink of any one of Claims 1-7 characterized by the above-mentioned. The water-based ink according to claim 1, wherein the azo pigment represented by the general formula (1) is represented by the following general formula (10).

(In General Formula (10), Z represents a 5- or 6-membered nitrogen-containing heterocycle, and W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group, or an aryl group.) The aqueous ink according to claim 9, wherein the azo pigment represented by the general formula (10) is represented by the following general formula (11).

(In general formula (11), Z represents a 6-membered nitrogen-containing heterocycle.)   The water-based ink according to claim 1, wherein the azo pigment is a pigment after-treated by salt milling.   The aqueous ink according to any one of claims 1 to 11, further comprising an acetylene surfactant.