JP2013032415A - Azo pigment, method for producing azo pigment, dispersion containing azo pigment, tinting composition and ink for inkjet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an azo pigment which is extremely good in color reproducibility, dispersibility and pigment dispersion stability, and has excellent hue and coloration power.SOLUTION: The method for producing the azo pigment represented by the formula and having characteristic X-ray diffraction peaks at Bragg angles (2θ±0.2°) of 4.8°, 9.2° and 13.0° in CuKα characteristic X-ray diffraction, or its tautomer is characterized by subjecting an azo pigment represented by the formula and having characteristic X-ray diffraction peaks at any Bragg angles (2θ±0.2°) of (i) 6.6°, 9.2° and 21.4°, (ii) 4.8°, 7.2° and 9.7°, or (iii) 5.9°, 7.0° and 8.9° in CuKα characteristic X-ray diffraction, or its tautomer to a solvent thermal treatment.

Description

  The present invention relates to an azo pigment, a method for producing an azo pigment, a dispersion containing an azo pigment, a coloring composition, and an ink for inkjet recording.

  In recent years, a material for forming a color image has been mainly used as an image recording material, and specifically, an ink jet recording material, a thermal transfer recording material, an electrophotographic recording material, a transfer halogen. Silver halide photosensitive materials, printing inks, recording pens, and the like are actively used. Further, a color filter is used for recording and reproducing a color image on an image pickup device such as a CCD in a photographing apparatus and on an LCD or PDP in a display. In these color image recording materials and color filters, three primary colors (dyes and pigments) of the so-called additive color mixing method and subtractive color mixing method are used to display or record full color images. The fact is that there are no fast-acting dyes that have absorption characteristics that can satisfy the above conditions and that can withstand various use conditions and environmental conditions, and improvements are strongly desired.

The dyes and pigments used in each of the above applications must have the following properties in common. That is, it has preferable absorption characteristics in terms of color reproducibility, fastness under environmental conditions to be used, for example, light resistance, heat resistance, good resistance to oxidizing gases such as ozone, and the like. In addition, when the pigment is a pigment, it is further substantially insoluble in water and organic solvents and has good chemical fastness, and even when used as particles, the preferred absorption characteristics in the molecular dispersion state are impaired. It is also necessary to have properties such as absence. The required characteristics can be controlled by the strength of intermolecular interaction, but it is difficult to achieve both because they are in a trade-off relationship.
In addition, when using the pigment, in addition to having a particle size and a particle shape necessary for expressing the desired transparency, fastness under the environmental conditions used, such as light resistance, heat resistance, Resistant to oxidizing gases such as ozone, water resistance, chemical fastness to other organic solvents and sulfurous acid gas, etc., dispersed to fine particles in the medium used, and stable dispersion state It is also necessary to have properties such as

  In other words, the required performance for pigments is wider than dyes that require performance as pigment molecules, and not only the performance as pigment molecules but also the above requirements as a solid (fine particle dispersion) as an aggregate of pigment molecules All performance needs to be satisfied. As a result, the group of compounds that can be used as pigments is extremely limited compared to dyes, and even if high-performance dyes are derived into pigments, there are only a few that can satisfy the required performance as fine particle dispersions. It cannot be developed. This is confirmed by the fact that the number of pigments registered in the color index is less than 1/10 of the number of dyes.

Among the pigments, azo pigments are particularly widely used as printing inks, ink-jet inks, electrophotographic materials, and color filter pigments because of their high lightness and excellent light resistance and heat resistance. With the expansion of applications, pigments are required to have even better stability over time, regardless of the medium used, than the level of stability normally used in printing inks, gravure inks and colorants. For example, Patent Document 1 discloses an azo pigment having a specific structure having a pyrazole ring which is excellent in color characteristics such as hue and excellent in light resistance.
At the same time, in applications such as color filters and ink-jet inks, it is required to further improve the clarity and transparency. In order to improve the sharpness and transparency, it is effective to finely disperse the pigment, and an efficient method for producing fine azo pigment particles capable of forming a fine dispersion has been demanded. Patent Document 2 discloses a method for producing an azo pigment having a specific structure having a pyrazole ring that can be produced with high efficiency and low cost.

On the other hand, many of the typical organic pigments are polymorphic, and it is known that such pigments take two or more crystalline forms despite having the same chemical composition.
Some organic pigments, such as azo pigments, can obtain finely sized particles by selecting appropriate reaction conditions during synthesis, such as copper phthalocyanine green pigments during synthesis. The very fine and agglomerated particles that are produced are pigmented by particle growth and sizing in the subsequent process, such as copper phthalocyanine blue pigment, coarse and irregular particles that are produced during synthesis are refined in the subsequent process, Some pigments are made by sizing. For example, a diketopyrrolopyrrole pigment is generally synthesized by reacting an oxalic acid diester and an aromatic nitrile in an organic solvent (see, for example, Patent Document 3). Then, the crude diketopyrrolopyrrole pigment is made into a form suitable for use by heat treatment in water or an organic solvent and then powdering such as wet grinding (for example, see Patent Document 4). C. I. For pigment red 254, α-type and β-type crystal forms are known (see, for example, Patent Document 5). Further, C.I. which is an azo pigment. I. Pigment Yellow 181 has several known crystal forms (see, for example, Patent Document 6).

JP 2010-31224 A JP 2011-74375 A JP 58-210084 JP-A-5-222314 JP-A-8-48908 US Patent Application Publication No. 2008/0058531

As for the azo pigments described in Patent Documents 5 and 6, there is no description of knowledge regarding the crystal form as described above. Moreover, there was no description about the filterability which is the performance required for the pigment, and there was room for further study.
An object of the present invention is to provide an azo pigment which is a novel crystal form having a specific structure having a pyrazole ring, which is compatible not only with color characteristics such as hue and light resistance, but particularly with filterability and dispersibility. It is what.
An object of the present invention is to provide a process for producing the azo pigment, which is a novel crystal form that can be produced with high reproducibility and high efficiency while being controlled to a specific crystal form.
It is another object of the present invention to provide a dispersion of the azo pigment, a coloring composition containing the dispersion of the azo pigment, and an ink for inkjet recording.

As a result of intensive studies in view of the above circumstances, the inventors of the present invention have characteristic Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction of 4.8 °, 9.2 °, and 13.0 °. The azo pigment represented by the following formula (1) having an X-ray diffraction peak or a tautomer thereof has not only color characteristics such as hue and light resistance, but particularly both filterability and dispersibility. I found out.
Further, the inventors have found a method for producing an azo pigment capable of producing an azo pigment with high reproducibility and high efficiency while controlling to a specific crystal form, and have completed the present invention.
Formula (1)

〔２〕
前記アゾ顔料が、ＣｕＫα特性Ｘ線回折におけるブラッグ角（２θ±０．２°）の４．８°、６．５°、９．２°、９．７°、１３．０°及び２４．４°に特徴的Ｘ線回折ピークを有する、〔１〕記載のアゾ顔料、又はその互変異性体。
〔３〕
ＣｕＫα特性Ｘ線回折におけるブラッグ角（２θ±０．２°）の
（ｉ）６．６°、９．２°および２１．４°
（ｉｉ）４．８°、７．２°及び９．７°
（ｉｉｉ）５．９°、７．０°及び８．９°
のいずれかに特徴的Ｘ線回折ピークを有する下記式（１）で表されるアゾ化合物又はその互変異性体を、溶媒加熱処理することを特徴とする、
ＣｕＫα特性Ｘ線回折におけるブラッグ角（２θ±０．２°）の４．８°、９．２°及び１３．０°に特徴的Ｘ線回折ピークを有する、下記式（１）で表されるアゾ顔料、又はその互変異性体の製造方法。
式（１）

〔４〕
〔３〕に記載の製造方法で製造されたことを特徴とする〔１〕又は〔２〕に記載のアゾ顔料。
〔５〕
ＣｕＫα特性Ｘ線回折におけるブラッグ角（２θ±０．２°）の６．６°、９．２°および２１．４°に特徴的Ｘ線回折ピークを有する下記式（１）で表されるアゾ化合物又はその互変異性体のアセトン溶媒和物。
式（１）

〔６〕
〔１〕又は〔２〕に記載のアゾ顔料を含有することを特徴とする顔料分散物。
〔７〕
顔料分散物中の顔料粒子の体積平均粒子径が０．０１μｍ〜０．２μｍであることを特徴とする〔６〕に記載の顔料分散物。
〔８〕
〔１〕若しくは〔２〕に記載のアゾ顔料又は〔６〕若しくは〔７〕に記載の顔料分散物を含有することを特徴とする着色組成物。
〔９〕
〔１〕若しくは〔２〕に記載のアゾ顔料又は〔６〕若しくは〔７〕に記載の顔料分散物又は〔８〕に記載の着色組成物を含有することを特徴とするインクジェット記録用インク。 That is, the present invention is as follows.
[1]
The Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction is expressed by the following formula (1) having characteristic X-ray diffraction peaks at 4.8 °, 9.2 °, and 13.0 °. An azo pigment or a tautomer thereof.
Formula (1)

[2]
The azo pigment has a Bragg angle (2θ ± 0.2 °) of 4.8 °, 6.5 °, 9.2 °, 9.7 °, 13.0 ° and 24.4 in CuKα characteristic X-ray diffraction. The azo pigment according to [1], which has a characteristic X-ray diffraction peak at °, or a tautomer thereof.
[3]
(I) 6.6 °, 9.2 ° and 21.4 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction
(Ii) 4.8 °, 7.2 ° and 9.7 °
(Iii) 5.9 °, 7.0 ° and 8.9 °
The azo compound represented by the following formula (1) having a characteristic X-ray diffraction peak in any of the above or a tautomer thereof is characterized by being subjected to a solvent heat treatment,
It is represented by the following formula (1) having characteristic X-ray diffraction peaks at 4.8 °, 9.2 °, and 13.0 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction. A method for producing an azo pigment or a tautomer thereof.
Formula (1)

[4]
The azo pigment according to [1] or [2], which is produced by the production method according to [3].
[5]
An azo represented by the following formula (1) having characteristic X-ray diffraction peaks at 6.6 °, 9.2 °, and 21.4 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction Acetone solvate of the compound or a tautomer thereof.
Formula (1)

[6]
A pigment dispersion comprising the azo pigment according to [1] or [2].
[7]
The pigment dispersion according to [6], wherein the volume average particle diameter of the pigment particles in the pigment dispersion is 0.01 μm to 0.2 μm.
[8]
A coloring composition comprising the azo pigment according to [1] or [2] or the pigment dispersion according to [6] or [7].
[9]
An ink for ink jet recording comprising the azo pigment according to [1] or [2], the pigment dispersion according to [6] or [7], or the coloring composition according to [8].

According to the present invention, not only chromatic properties such as hue, light resistance, but also a novel pyrazole ring having a specific substituent that is compatible with both filterability and dispersibility is connected via an azo group and a triazine ring. An azo pigment that is a crystalline form, a dispersion of the azo pigment, and a coloring composition are provided.
Furthermore, there is provided a process for producing the azo pigment, which can produce the azo pigment with high reproducibility and high efficiency while controlling to a specific crystal form.

3 is an X-ray diffraction pattern of a ζ-type crystal form azo pigment (1) -1 synthesized in Synthesis Example 1. FIG. 3 is an X-ray diffraction pattern of an η-type crystal form azo pigment (1) -1 synthesized in Synthesis Example 1. FIG. FIG. 4 is an X-ray diffraction pattern of a γ-type crystal form azo pigment (1) -2 synthesized in Synthesis Example 2. 6 is an X-ray diffraction pattern of an η-type crystal form azo pigment (1) -2 synthesized in Synthesis Example 2. FIG. 6 is an X-ray diffraction pattern of an η-type crystal form azo pigment (1) -3 synthesized in Synthesis Example 3. FIG. 4 is an X-ray diffraction pattern of an amorphous azo compound (1) -4 synthesized in Comparative Synthesis Example 1. FIG.

Hereinafter, the present invention will be described in detail.
The azo pigment of the present invention or a tautomer thereof may be a hydrate, a solvate or a salt thereof.

  The azo pigment in the embodiment of the present invention has the following formula having characteristic X-ray diffraction peaks at Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction of 4.8 °, 9.2 °, and 13.0 °. The azo pigment represented by (1), or a tautomer thereof.

In the present specification, a formula (1) having characteristic X-ray diffraction peaks at Bragg angles (2θ ± 0.2 °) of 4.8 °, 9.2 °, and 13.0 ° in CuKα characteristic X-ray diffraction will be described below. The azo pigment represented by) is referred to as η-type crystal form azo pigment.
Also, characteristic X-ray diffraction peaks at CuKα characteristic X-ray diffraction with Bragg angles (2θ ± 0.2 °) of 6.6 °, 9.2 °, 10.3 °, 21.4 ° and 25.6 ° The azo pigment represented by the formula (1) having the formula is referred to as ζ-type crystal form azo pigment.
Further, the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction is represented by the formula (1) having characteristic X-ray diffraction peaks at 5.9 °, 7.0 °, and 8.9 °. The azo pigment is referred to as a γ-type crystal form azo pigment.
An azo represented by the formula (1) having characteristic X-ray diffraction peaks at Bragg angles (2θ ± 0.2 °) of 4.8 °, 7.2 °, and 9.7 ° in CuKα characteristic X-ray diffraction The pigment is referred to as a δ-type crystal form azo pigment.

  In the present invention, the X-ray diffraction measurement of the η-type crystal form azo pigment represented by the following formula (1) is performed in accordance with Japanese Industrial Standard JISK0131 (general rules for X-ray diffraction analysis). (Manufactured by Rigaku Corporation).

  FIG. 2 shows an X-ray diffraction diagram, and characteristic X-ray diffraction peaks are observed at Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction of 4.8 °, 9.2 °, and 13.0 °. The azo pigment represented by formula (1) will be described in more detail.

In the case of a single crystal form, the molecules become dense and the intermolecular interaction becomes strong. As a result, filterability, dispersibility, solvent resistance, thermal stability, light resistance, gas resistance, printing density are increased, and the color reproduction range is further expanded. Among them, as a crystal form having both filterability and dispersibility, the azo pigment represented by the formula (1) and its tautomer are Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction. Is preferred to have a crystalline form having characteristic X-ray diffraction peaks at 4.8 °, 9.2 ° and 13.0 °.
Crystal forms with characteristic X-ray diffraction peaks at 4.8 °, 9.2 ° and 13.0 ° are further 4.8 °, 6.5 °, 9.2 °, 9.7 °, A crystal form exhibiting an X-ray diffraction pattern having significant X-ray diffraction lines at 13.0 ° and 24.4 ° is more preferable. Among them, X-ray diffraction patterns having prominent X-ray diffraction lines at 4.8 °, 6.5 °, 9.2 °, 9.7 °, 13.0 °, 22.0 ° and 24.4 °. The crystal form showing is most preferred.

  The reason why the azo pigment represented by the formula (1) having characteristic X-ray diffraction peaks at 4.8 °, 9.2 °, and 13.0 ° has both filterability and dispersibility is the crystal form. This is considered to be because it is possible to perform filtration with a particle size that provides good filterability by controlling the degree of crystal growth. If the crystal growth proceeds too much, the particle size becomes too large and the load during dispersion becomes large. The azo pigment having a specific crystal form of the present invention does not have an excessively large particle size, and has both filterability and dispersibility. The reason why such a particle size can be obtained is that by taking a specific molecular arrangement, it has solubility specific to the crystal type, and since the surface area is large when the particle size is small, the dissolution proceeds and the crystal that becomes the nucleus Will grow. When growing to a certain particle size, the growth and dissolution rates are balanced, and crystal growth becomes difficult. Due to the balance, the particle size is considered suitable for having both filterability and dispersibility.

  In the η-type crystal form azo pigment represented by the formula (1), a hydrate containing water molecules in the crystal, or a solvent (for example, alcohols such as methanol, ethanol, 2-propanol, t-butyl alcohol, Ketones such as acetone and methyl ethyl ketone, aprotic solvents such as acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone and toluene, preferably acetone and N-methyl-2-pyrrolidone, More preferably, it may be a solvate containing acetone).

  In addition, with respect to the η-type crystal form azo pigment represented by the formula (1), tautomers thereof (for example, azo-hydrazone tautomers and geometric isomers represented by the formula (4)) are also available. In the present invention, these general formulas are included.

  The length in the major axis direction when the primary particles are observed with a transmission microscope is preferably 0.01 μm or more and 30 μm or less. When the length is 0.01 μm or more, it has excellent fastness to light and ozone, suppresses aggregation and improves dispersibility. On the other hand, when it is 30 μm or less, it is difficult to be in an overdispersed state when dispersed to obtain a desired volume average particle diameter, and it is easy to suppress agglomeration, so that the storage stability of the pigment dispersion is excellent.

  If the length in the major axis direction of the primary particles is within the above range, the pigment particles exhibit high fastness to light and ozone, and the pigment dispersion is excellent in storage stability and preferable.

  Therefore, the length in the major axis direction when the primary particles of the η-type crystal form azo pigment represented by the following formula (1) are observed with a transmission microscope is preferably 0.01 μm or more and 30 μm or less. 0.02 μm or more and 20 μm or less is more preferable, and 0.03 μm or more and 10 μm or less is most preferable.

  Furthermore, the present invention becomes an intermediate in the method for producing an azo pigment represented by the formula (1) having characteristic X-ray diffraction peaks at 4.8 °, 9.2 ° and 13.0 ° which will be described later. 6.6 °, 9.2 °, 10.3 °, 21.4 ° and 25.6 ° (ζ), or 5.9 °, 7.0 ° and 8.9 ° (γ), or 4. The present invention also relates to an azo pigment represented by the following formula (1) having characteristic X-ray diffraction peaks at 8 °, 7.2 °, and 9.7 ° (δ), or a solvate of a tautomer thereof. .

  Below, the synthesis | combination of the (eta) type crystal form azo pigment represented by Formula (1) is demonstrated in detail.

The η-type crystal form azo pigment represented by the formula (1) (hereinafter sometimes simply referred to as “azo pigment” or “pigment”) can be synthesized by the following production method.
The production method of the present invention preferably includes a step of subjecting a diazonium salt derived from a heterocyclic amine represented by the following formula (2) and a compound represented by the following formula (3) to an azo coupling reaction.

Below, the manufacturing method of this invention is demonstrated in detail.
The method for producing an azo pigment of the present invention preferably includes a step of obtaining a crude azo pigment and a step of converting the crude azo pigment into a η-type crystal form azo pigment by solvent treatment.
The method for producing the crude azo pigment is:
(A) a step of mixing a diazotizing agent and a heterocyclic amine represented by formula (2);
(B) Reaction is performed by mixing the reaction product obtained in step (a) with the compound represented by formula (3), and at least of the azo compound represented by formula (1) produced by the reaction Obtaining a partially dissolved solution;
Preferably including
(C) mixing the solution obtained in step (b) with a poor solvent for the azo compound represented by formula (1) to crystallize the pigment represented by formula (1). Is more preferable.
In the step (b), it is preferable that the ratio of the dissolved azo compound is high because the yield increases.

The step (a) according to the present invention will be described in detail.
In the step (a), the diazonium compound and the heterocyclic amine represented by the formula (2) are mixed to form a diazonium compound by the reaction between the heterocyclic amine represented by the formula (2) and the diazotizing agent. Be guided. This reaction is preferably carried out in a medium containing an acid. In this specification, a liquid containing the diazonium compound is referred to as a “diazonium compound preparation liquid”. The method for mixing the heterocyclic amine represented by formula (2), the acid and the diazotizing agent is not particularly limited, but the diazotizing agent is added to the solution of the heterocyclic amine represented by formula (2) and the acid. It is preferable to do. The diazotizing agent in the step (a) is used for deriving the heterocyclic amine represented by the formula (2) to a diazonium compound, and is not limited as long as it has such an action. . Representative examples of the diazotizing agent include nitrites (for example, isopentyl nitrite), nitrites (for example, sodium nitrite and potassium nitrite), isoamyl nitrite, and nitrosyl sulfate. More preferred are sodium nitrite, potassium nitrite, and nitrosylsulfuric acid. Among them, nitrosylsulfuric acid is particularly preferred from the viewpoint that a diazonium compound can be stably and efficiently prepared.

  The acid used in the step (a) means an acid that can be slightly dissolved even if the heterocyclic amine represented by the formula (2) is not completely dissolved, and is preferably an acid that completely dissolves the amino compound. As the acid, an inorganic acid and an organic acid can be used. Examples of the inorganic acid include hydrochloric acid, phosphoric acid, and sulfuric acid, preferably phosphoric acid and sulfuric acid, and more preferably sulfuric acid. Examples of the organic acid include formic acid, acetic acid, propionic acid, and methanesulfonic acid, preferably acetic acid, propionic acid, and methanesulfonic acid, and more preferably acetic acid and propionic acid. These acids may be used alone or in combination. Examples of the mixed acid include phosphoric acid / acetic acid, sulfuric acid / acetic acid, methanesulfonic acid / acetic acid, acetic acid / propionic acid, and preferably phosphoric acid / acetic acid, sulfuric acid / acetic acid, sulfuric acid / acetic acid / propionic acid, acetic acid / propionic acid. Of these, sulfuric acid / acetic acid and acetic acid / propionic acid are particularly preferred. 1 / (0.1-20) is preferable, as for the mass ratio of these mixed acids, 1 / (0.5-10) is more preferable, More preferably, it is 1 / (1-10).

In step (a), the amount of acid added to the heterocyclic amine represented by formula (2) is 1 to 100 times, more preferably 2 to 50 times, and even more preferably 3 to 25 times in terms of mass ratio. . When the mass ratio is 1 or more, the stirrability is improved and the diazonium compound can be more reliably induced. On the other hand, when the mass ratio is 100 times or less, productivity becomes economical for improvement.
Moreover, the addition amount of the diazotizing agent with respect to the heterocyclic amine represented by the formula (2) in the step (a) is 1.0 to 20 times in molar ratio, more preferably 1.0 to 10 times. Yes, 1.0 to 5 times is more preferable. When the diazotizing agent has a molar ratio of 1 or more with respect to the amino compound, the diazonium compound can be more reliably induced.

  In the mixing of the diazotizing agent and the heterocyclic amine represented by formula (2) in step (a), it is preferably carried out at 50 ° C. or lower, more preferably carried out at 40 ° C. or lower, still more preferably. It is desirable to carry out at 30 degrees C or less. In the preparation of a diazo liquid at a temperature higher than 50 ° C., there is a concern about the decomposition of the diazotizing agent. The stirring time for inducing the diazonium compound is preferably 0.3 to 10 hours, more preferably 0.5 to 5 hours, and further preferably 1 to 3 hours. When the stirring time is 0.3 hours or longer, the diazonium compound is easily induced completely, and when it is 10 hours or shorter, the diazonium compound is hardly decomposed. Moreover, a normal stirrer is used for mixing, and there is no limitation in particular. Although depending on the production equipment, the rotation speed of the preferable stirring is preferably 30 to 300 rpm, more preferably 40 to 200 rpm, and still more preferably 50 to 200 rpm. Since the stirring efficiency of the diazonium compound preparation liquid is good when the stirring speed is 30 rpm or more, the progress of a desired reaction can be reliably performed.

  The solvent that can be mixed in the step (a) is not particularly limited as long as the derived diazonium compound is not decomposed. Examples of miscible solvents include hydrocarbon solvents such as hexane, benzene and toluene, ether solvents such as diethyl ether and tetrahydrofuran, ketone solvents such as acetone and methyl ethyl ketone, dimethylformamide, dimethylacetamide, pyrrolidone and N-methyl- Examples include amide solvents such as 2-pyrrolidone, other dimethyl sulfoxide, sulfolane, acetonitrile, and water.

  The preferred pH of the diazonium compound preparation solution in step (a) is preferably 7 or less, more preferably 5 or less, and even more preferably 3 or less. When the pH of the diazonium compound preparation solution in step (a) is higher than 7, there is a concern about the decomposition of the induced diazonium compound.

Next, the step (b) according to the present invention will be described in detail.
In step (b), the reaction product obtained in step (a) is mixed with the compound represented by formula (3), and the reaction is represented by formula (1) generated by the reaction. This is a step of obtaining a solution in which at least a part of the azo compound is dissolved.
In this specification, a solution in which at least a part of the azo compound is dissolved is referred to as an “azo compound solution”.

  As a preparation method of the azo compound solution, (i) a coupling reaction is performed by mixing the reaction product obtained in step (a) and the compound represented by formula (3). And (ii) at least a part of the compound represented by the formula (1) obtained by the above coupling reaction is contained in the reaction solution, wherein the azo pigment represented by the formula (1) is dissolved in a solvent. The coupling reaction is carried out so as to dissolve, and the reaction solution is used as it is as an azo compound solution, or the azo compound solution thus obtained is described in detail below (c The method is obtained by further dissolving (crystallized) the azo pigment obtained by application to (1) in a solvent.

  In any of the above forms (i) and (ii), the method for mixing the diazonium compound preparation liquid obtained in step (a) and the coupling component is not particularly limited, but the coupling component is partly used as a solvent. Alternatively, it is more preferable to add all of them by dissolving them, or to add the coupling component as a solid in the diazonium compound preparation liquid obtained in step (a).

  The amount of the diazonium compound in the diazonium compound preparation liquid obtained in the step (a) with respect to the compound represented by the formula (3) in the step (b) is the coupling position of the compound represented by the formula (3). Is preferably 0.8 to 3 equivalents, more preferably 0.9 to 2 equivalents to the coupling position, and still more preferably 0.95 to 1.5 equivalents to the coupling position. By being 0.8 equivalents or more, the remaining of the coupling component having an unreacted coupling position can be suppressed, and by being 3 equivalents or less, the remaining of the unreacted diazonium compound can be suppressed. Economical.

  In addition, in the said form (ii), since at least one part of the azo compound represented by Formula (1) is melt | dissolving in process (b), coupling reaction advances more smoothly and more highly purified. An azo compound can be produced. The reason is presumed as follows. Since there are two coupling positions, for example, it passes through a reaction intermediate in which only one coupling position has reacted. If this reaction intermediate precipitates in the reaction system, the reaction rate of the second coupling reaction becomes slow. On the other hand, since the diazonium compound is unstable, there is a concern that decomposition may occur after a long time. Therefore, it is important that the coupling reaction proceeds quickly, and the production method of the above form (ii) that does not generate precipitates in the step (b) results in producing a high-purity pigment. More preferred.

  In the step (b), a coupling component may be added without using a solvent, but it is preferable to add it by mixing with a solvent. When a solvent is used for the coupling component in the step (b), there is no particular limitation, but the azo compound represented by the general formula (1) generated after the reaction is formed so as to have the above form (ii). The solvent is preferably such that a solution in which at least a part is dissolved is obtained.

  In the case of the above form (i), that is, when the pigment is precipitated, water, organic acid, inorganic acid, and organic solvent can be used as examples of the solvent. It is preferable to use a solvent that exhibits a uniform solution with the solvent. For example, water, methanol, ethanol, propanol, isopropanol, butanol, t-butyl alcohol, alcoholic organic solvents such as amyl alcohol, ketone organic solvents such as acetone and methyl ethyl ketone, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, Diol glycol, diol organic solvents such as 1,3-propanediol, ether organic solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, tetrahydrofuran, dioxane, acetonitrile, etc. The solvent may be a mixture of two or more.

  Preferably, the organic solvent has a polarity parameter (ET) value of 40 or more. Among them, a glycol solvent having two or more hydroxyl groups in a solvent molecule, an alcohol solvent having 3 or less carbon atoms, a ketone solvent having a total carbon number of 5 or less, preferably an alcohol having 2 or less carbon atoms. Solvents (for example, methanol, ethylene glycol) and ketone solvents having a total carbon number of 4 or less (for example, acetone, methyl ethyl ketone) are preferable. These mixed solvents are also included.

In the case of the above form (ii), that is, when the coupling reaction is performed so that at least a part of the compound represented by the formula (1) is dissolved in the reaction solution, examples of the solvent include methanol, isopropanol, Alcohol solvents such as ethylene glycol, ketone solvents such as acetone and methyl ethyl ketone, organic acid solvents such as acetic acid, propionic acid and methanesulfonic acid, inorganic acid solvents such as sulfuric acid, hydrochloric acid and phosphoric acid, dimethylformamide, dimethylacetamide and pyrrolidone Amide solvents such as N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, and acetonitrile. Among them, preferred are ketone solvents such as acetone and methyl ethyl ketone, organic acid solvents such as acetic acid, propionic acid and methanesulfonic acid, and inorganic acid solvents such as sulfuric acid, hydrochloric acid and phosphoric acid, and more preferred are organic acids or inorganic acids. Acidic acid solvents, most preferably acetic acid, methanesulfonic acid, phosphoric acid and sulfuric acid. Moreover, the mixed solvent of the solvent shown above is also suitable.
Particularly in the case of the above form (ii), in the step (b), an acidic solution obtained by dissolving or suspending a coupling component in an acidic solvent and the reaction product obtained in the step (a) are mixed, or a cup The ring component is preferably added to the reaction product obtained in step (a) without using a solvent. In particular, the acidic solvent is preferably a solvent containing at least one of acetic acid and sulfuric acid.

  In any of the above forms (i) and (ii), the preferred amount of the solvent added to the coupling component is preferably 0.5 to 200 times, more preferably 1 to 100 times, and 1 to 50 times in terms of mass ratio. Further preferred. When the preferred amount of the solvent for the coupling component is less than 0.5 times by mass, stirring in the production machine for the coupling component and the solvent becomes difficult, and the desired reaction does not proceed. If it is larger than 200 times, it becomes uneconomical.

  When the preparation method of the azo compound solution is the above-mentioned form (i), or a coupling in which at least a part of the compound represented by the formula (1) is dissolved in the above-mentioned form (ii) In the case of preparing an azo compound solution by further dissolving the azo pigment obtained by applying the reaction solution to the step (c) in a solvent, the solvent for dissolving the obtained azo pigment is: Although it will not specifically limit if at least one part can be melt | dissolved, The example of the solvent mentioned above as preferable in the said form (ii) can be mentioned similarly.

  Regardless of the steps of the above forms (i) and (ii), the azo compound solution finally obtained in step (b) is preferably an acidic solution, and in particular, at least acetic acid and sulfuric acid. A solution containing one is preferable.

  As the azo compound solution obtained in the step (b), the total amount of the azo compound produced in the step (b) (the azo compound represented by the formula (1) dissolved in the azo compound solution and the azo compound dissolved) The ratio of the azo compound represented by formula (1) dissolved in the azo compound solution to the total of the azo pigments represented by formula (1) precipitated from the liquid is 50% by mass or more. Preferably, it is preferably 75% by mass or more, preferably 90% by mass or more, and 100% by mass (the state in which the azo compound produced in the step (b) is completely dissolved in the reaction solution). Is most preferable, and this tends to further reduce the particle diameter of the pigment. Moreover, since the yield becomes high when the ratio which the azo compound is melt | dissolving is high, it is preferable.

  In the step (b), the mixing temperature of the diazonium compound preparation liquid and the coupling component in the step (a) is preferably 50 ° C. or lower, more preferably 30 ° C. or lower, still more preferably 25 ° C. It is desirable to carry out the following. Above 50 ° C., there is concern about the decomposition of the diazonium compound derived in step (a) and the azo compound represented by formula (1). Moreover, a normal stirrer is used for mixing, and there is no limitation in particular. Although depending on the production equipment, the rotational speed of the preferred stirring is preferably 30 to 400 rpm, more preferably 40 to 300 rpm, and still more preferably 50 to 200 rpm. When the stirring speed is 30 rpm or less, the stirring efficiency of the mixed solution deteriorates and there is a concern about the progress of a desired reaction. The stirring time in the step (b) is preferably from 0.1 to 10 hours, more preferably from 0.3 to 5 hours, still more preferably from 0.3 to 3 hours. If it is less than 0.1 hour, it is difficult to induce the pigment completely, and if it is longer than 10 hours, there is a concern about decomposition of the azo compound represented by the formula (1).

Next, the details of the step (c) according to the present invention will be described.
Step (c) is a step of crystallizing the pigment by mixing the azo compound solution obtained in step (b) with a poor solvent having low solubility of the azo compound. There is no particular limitation on the method of mixing the azo compound solution obtained in step (b) and the poor solvent, but it is preferable to add the azo compound solution obtained in step (b) to the poor solvent. In this case, the poor solvent is preferably stirred.
The stirring speed is preferably 100 to 10000 rpm, more preferably 150 to 8000 rpm, and particularly preferably 200 to 6000 rpm. A pump or the like can be used for the addition. At this time, it may be added in the liquid or outside the liquid, but the addition in the liquid is more preferable. Furthermore, it is preferable to continuously supply the liquid by a pump through a supply pipe.

  Although a poor solvent is not specifically limited, It is preferable that the solubility of the azo compound represented by Formula (1) is 1 g / L or less, and it is more preferable that it is 0.1 g / L or less. This solubility may be the solubility when dissolved in the presence of an acid or alkali. The compatibility or uniform mixing of the azo compound solution obtained in step (b) and the poor solvent is preferably such that the amount of the good solvent of the azo compound dissolved in the poor solvent is 30% by mass or more, and 50% by mass or more. It is more preferable that In this specification, solubility refers to solubility at 25 ° C.

  Examples of the poor solvent include water, hydrochloric acid, aqueous ammonia, aqueous solvents such as aqueous sodium hydroxide, alcohol solvents such as methanol, ethanol, isopropyl alcohol, and 1-methoxy-2-propanol, and glycols such as ethylene glycol and diethylene glycol. Solvents, ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ether solvents such as diethyl ether and tetrahydrofuran, hydrocarbon solvents such as hexane, benzene and toluene, nitrile solvents such as acetonitrile, dichloromethane, trichloroethylene And halogenated solvents such as ethyl acetate, ethyl lactate, ester solvents such as 2- (1-methoxy) propyl acetate, etc., preferably water, hydrochloric acid, aqueous ammonia, hydroxylated Aqueous solvents such as aqueous thorium, alcoholic solvents such as methanol, ethanol, isopropyl alcohol and 1-methoxy-2-propanol, glycolic solvents such as ethylene glycol and diethylene glycol, and ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone It is a solvent, More preferably, they are water, aqueous solvents, such as aqueous ammonia, a C1-C3 alcohol solvent, and a C1-C6 glycol solvent. Moreover, the mixed solvent of the solvent shown above is also suitable. Most preferably, it is at least one solvent selected from the group consisting of water, alcohols having 1 to 3 carbon atoms, and glycols having 1 to 6 carbon atoms.

  The volume ratio of the azo compound solution obtained in the step (b) and the poor solvent is preferably 1/50 to 2/3, more preferably 1/40 to 1/2, and 1/20 to 1/2. Is particularly preferred. When the volume ratio is 2/3 or less, the pigment is sufficiently crystallized to increase the reaction yield, and when the volume ratio is 1/50 or more, the productivity is improved and economical.

  Although there is no restriction | limiting in particular in the mixing temperature of the azo compound solution obtained by the process (b) and a poor solvent, It is preferable to implement at -10-50 degreeC, and to implement at -5-30 degreeC. More preferably, it is most preferably carried out at -5 to 25 ° C.

  In mixing the azo compound solution obtained in the step (b) and the poor solvent, the particle size of the organic nanoparticles to be deposited can be controlled by adjusting the Reynolds number. Here, the Reynolds number is a dimensionless number representing the state of fluid flow and is represented by the following equation.

    Formula (1): Re = ρUL / μ

(In formula (1), Re represents the Reynolds number, ρ represents the density [kg / m ³ ] of the azo compound solution obtained in step (b), and U meets the azo compound solution and the poor solvent. Relative velocity [m / s], L represents the equivalent diameter [m] of the flow path or supply port of the portion where the azo compound solution meets the poor solvent, and μ represents the viscosity coefficient [Pa] of the azo compound solution. Represents s].

  The equivalent diameter L refers to the diameter of the equivalent circular pipe when assuming an opening diameter of a pipe having an arbitrary cross-sectional shape or a circular pipe equivalent to the flow path. The equivalent diameter L is expressed by the following formula (2), where A is the cross-sectional area of the pipe, p is the wetted length (circumferential length) of the pipe, or p is the outer periphery of the flow path.

    Formula (2): L = 4A / p

  The relative speed U when the azo compound solution and the poor solvent meet is defined by the relative speed in the direction perpendicular to the surface of the part where both meet. That is, for example, when the azo compound solution is injected and mixed in a stationary poor solvent, the speed of injection from the supply port becomes equal to the relative speed U. The value of the relative speed U is not particularly limited, but is preferably 0.5 to 100 m / s, and more preferably 1.0 to 50 m / s.

The density ρ of the azo compound solution is a value determined by the type of material selected, but is practically 0.8 to 2.0 kg / m ³ , for example. Further, the viscosity coefficient μ of the azo compound solution is also a value determined by the material used, the environmental temperature, and the like. More preferably, it is s.

  The smaller the value of the Reynolds number, the easier it is to form a laminar flow, and the larger the value, the easier it is to form a turbulent flow. For example, it can be obtained by adjusting the Reynolds number to 60 or more to control the particle diameter of the pigment nanoparticles, preferably 100 or more, and more preferably 150 or more. Although there is no particular upper limit to the Reynolds number, for example, pigment particles having a desired average particle diameter can be controlled and obtained by adjusting and controlling within a range of 100,000 or less. At this time, within the above range, it is possible to control and obtain pigment particles having a smaller particle size by increasing the Reynolds number.

  When the primary particles of the coarse azo pigment particles obtained by the production method of the present invention are observed with a transmission microscope, the length in the major axis direction is preferably 1 nm to 10 μm, and preferably 5 nm to 5 μm. More preferably, the thickness is 10 nm to 2 μm, more preferably 10 nm to 1 μm.

As for the particle diameter of the pigment particles, there is a method of expressing the average size of the group by quantifying by a measurement method, but as a frequently used method, the mode diameter indicating the maximum value of the distribution, the integral distribution curve There are median diameter corresponding to the median, various average diameters (number average, length average, area average, mass average, volume average, etc.). In the present invention, unless otherwise specified, the average particle diameter is Number average particle diameter.
Examples of the method for measuring the particle size of pigment particles include a microscopy method, a mass method, a light scattering method, a light blocking method, an electrical resistance method, an acoustic method, and a dynamic light scattering method. Particularly preferred. Examples of the microscope used for the microscopy include a scanning electron microscope and a transmission electron microscope. Examples of the particle measuring apparatus by the dynamic light scattering method include Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd. and Dynamic Light Scattering Photometer DLS-7000 series manufactured by Otsuka Electronics Co., Ltd.

  The preferred average particle diameter of the pigment particles is appropriately adjusted by (1) the temperature in step (c), (2) the solubility of the azo compound in the poor solvent, and (3) the stirring speed (or Reynolds number). To achieve.

In preparing the dispersion by depositing the coarse azo pigment fine particles, a dispersant may be contained in at least one of the azo compound solution and the poor solvent. At this time, it is preferable to contain a dispersant in the azo compound solution. The dispersant (1) has a function of quickly adsorbing on the surface of the deposited pigment to form fine nanoparticles and (2) preventing these particles from aggregating again.
As the dispersant, for example, anionic, cationic, amphoteric, nonionic low molecular or high molecular dispersants can be used.

The polymer dispersant preferably has a mass average molecular weight of 1,000 to 500,000, more preferably 10,000 to 500,000, and particularly preferably 10,000 to 100,000.
Specifically, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, polyethylene glycol, polypropylene glycol, polyacrylamide, vinyl alcohol-vinyl acetate copolymer, polyvinyl alcohol-bunformalized product, polyvinyl alcohol-partial butyralized product, vinylpyrrolidone- Vinyl acetate copolymer, polyethylene oxide / propylene oxide block copolymer, polyacrylate, polyvinyl sulfate, poly (4-vinylpyridine) salt, polyamide, polyallylamine salt, condensed naphthalenesulfonate, cellulose derivative, starch Derivatives and the like. In addition, natural polymers such as alginate, gelatin, albumin, casein, gum arabic, tonganto gum and lignin sulfonate can also be used. Of these, polyvinylpyrrolidone is preferable. These polymer compounds can be used singly or in combination of two or more, or a low molecular weight dispersant may be used in combination. The dispersant used for dispersing the pigment is described in detail on pages 29 to 46 of “Pigment dispersion stabilization and surface treatment technology / evaluation” (Chemical Information Association, issued in December 2001).

  Examples of anionic dispersants (anionic surfactants) include N-acyl-N-alkyl taurine salts, fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphorus Examples include acid ester salts, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl sulfate ester salts, and the like. Of these, N-acyl-N-alkyltaurine salts are preferred. As the N-acyl-N-alkyltaurine salt, those described in JP-A-3-273067 are preferable. These anionic dispersants can be used alone or in combination of two or more.

  Cationic dispersants (cationic surfactants) include quaternary ammonium salts, alkoxylated polyamines, aliphatic amine polyglycol ethers, aliphatic amines, diamines and polyamines derived from aliphatic amines and fatty alcohols, fatty acids And imidazolines derived from these and salts of these cationic substances. These cationic dispersants can be used alone or in combination of two or more.

The amphoteric dispersant is a dispersant having both an anion group part in the molecule of the anionic dispersant and a cation group part in the molecule of the cationic dispersant.
Nonionic dispersants (nonionic surfactants) include polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine And glycerin fatty acid ester. Of these, polyoxyethylene alkylaryl ether is preferable. These nonionic dispersants can be used alone or in combination of two or more.

  The content of the dispersant is preferably in the range of 0.1 to 1000 parts by weight, more preferably in the range of 1 to 500 parts by weight, and still more preferably in the range of 5 to 200 parts by weight with respect to 100 parts by weight of the pigment. Range. Moreover, a dispersing agent may be used independently or may be used in combination of multiple things.

  As an embodiment of the present invention, the azo compound solution obtained in the step (b) is in a state in which the azo compound is completely dissolved in the reaction solution, and this azo compound solution contains 1 to 3 carbon atoms. It is preferable to mix an alcohol, preferably methanol, as a poor solvent. By producing a crude azo pigment in such an embodiment, finally, a desired η-type crystal form azo pigment having a small particle diameter can be efficiently obtained.

  By the above production method, the compound represented by the above formula (1) is obtained as a crude azo pigment (crude). As a method for obtaining an azo pigment in a crystalline form, it is desirable to perform post-treatment. Examples of the post-treatment method include a pigment particle control step by grinding treatment such as solvent salt milling, salt milling, dry milling, solvent milling, and acid pasting, and solvent heating treatment.

For example, by mixing water as a poor solvent with the azo compound solution obtained in the step (b), an amorphous azo pigment is precipitated, and the amorphous azo pigment is converted into an η-type crystalline azo pigment by crystal conversion. A pigment can be obtained.
By mixing methanol as a poor solvent into the azo compound solution obtained in the step (b), a ζ-type crystal form azo pigment is precipitated, and the ζ-type crystal form azo pigment is crystallized to obtain a crystal form azo pigment. It can also be obtained.
Hereinafter, the crystal conversion will be described.

The crystal conversion in the present invention refers to conversion of a crystal form, and may be amorphous before conversion or may have a crystal form different from the crystal form after conversion. Examples of the crystal conversion method include the above-described post-treatment, and grinding treatment such as solvent salt milling, salt milling, dry milling, solvent milling, and acid pasting, and solvent heating treatment are preferred, and salt treatment is more preferred. Milling, solvent milling, and solvent heat treatment are preferred, and solvent heat treatment is particularly preferred.
According to crystal conversion, not only can a compound be converted from an amorphous state to a crystalline form, but also from a certain crystalline form to a different crystalline form.

The following formula (1) having characteristic X-ray diffraction peaks at 4.8 °, 9.2 ° and 13.0 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction of the present invention: In the CuKα characteristic X-ray diffraction (i) of 6.6 °, 9.2 °, and 21. 4 ° (Azo pigment with ζ-type crystal form)
(Ii) 4.8 [deg.], 7.2 [deg.] And 9.7 [deg.] ([Delta] -type crystal form azo pigment)
(Iii) 5.9 °, 7.0 ° and 8.9 ° (γ-type crystal form azo pigment)
The azo compound represented by the following formula (1) having a characteristic X-ray diffraction peak in any of the above or a tautomer thereof is subjected to a solvent heat treatment and then solvated by heating.
Formula (1)

(Solvent heat treatment)
In the present invention, the solvent heat treatment specifically refers to an amorphous azo compound represented by the formula (1), or a crystalline form of an azo pigment, a salt, hydrate or solvate thereof in a solvent. It means heating and stirring.
Crystal conversion can be efficiently performed by the solvent heating treatment. For example, a δ-type crystal form azo pigment can be obtained by heating and stirring a solvate of an amorphous form of an azo pigment.

Any of the ζ-type crystal form azo pigment, the δ-type crystal form azo pigment, and the γ-type crystal form azo pigment can be heat treated with a solvent to obtain an η-type crystal form azo pigment.
For example, an azo pigment having a ζ-type crystal form can be obtained by the above-described production method. The γ-type crystal form azo pigment can be obtained by the production method described later.
As the solvent used for the solvent heat treatment, a solvent having low solubility of the azo pigment represented by the formula (1) after crystal conversion is preferable from the viewpoint of suppressing crystal growth.

As the solvent for crystal conversion of the ζ-type crystal form azo pigment and the γ-type crystal form azo pigment to the η-type crystal form azo pigment, for example, ketone compounds, aromatic compounds, and acetonitrile are preferable. Among them, there are polar aprotic organic solvents such as acetone, methyl ethyl ketone, toluene, acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and mixtures thereof, among which acetone , Methyl ethyl ketone, toluene, acetonitrile and N-methyl-2-pyrrolidone are preferred, N-methyl-2-pyrrolidone or acetone is more preferred, and acetone is still more preferred. An inorganic or organic acid or base may be further added to the solvents mentioned above.
Solvents for crystal conversion of γ-type crystal form azo pigments to δ-type crystal form azo pigments include, for example, water, methanol, ethanol, isopropanol, isobutanol, ethylene glycol, diethylene glycol, diethylene glycol diethyl ether, diethylene glycol monomethyl ether , Dipropylene glycol, acetic acid, propionic acid, sulfuric acid, or a mixed solvent thereof is preferable, and ethylene glycol, water, acetic acid, sulfuric acid, or a mixed solvent thereof is more preferable, and ethylene glycol is most preferable. .

  The amount of the solvent used for the solvent heat treatment is preferably 1 to 100 times, more preferably 5 to 50 times that of the azo compound represented by the amorphous formula (1). More preferably, it is -30 times. If it is less than 1 time, the stirring property cannot be secured, which is not preferable. On the other hand, when the ratio is more than 100 times, productivity is deteriorated and it is not economical, which is not preferable.

  The temperature of the heating and stirring in the solvent heat treatment varies depending on the desired primary particle diameter of the pigment, but is preferably 15 to 150 ° C, more preferably 20 to 120 ° C, and still more preferably 20 to 100 ° C. If the temperature is lower than 15 ° C., it takes a long time because crystal conversion occurs, which is not efficient. On the other hand, a temperature higher than 150 ° C. is not preferable because part of the azo pigment (1) is decomposed. The solvent heat treatment is preferably performed under reflux.

  The stirring time for crystal conversion may be any number of minutes as long as crystal conversion occurs, but is preferably 5 to 1500 minutes, more preferably 10 to 600 minutes, and more preferably 30 to 300 minutes. If it is shorter than 5 minutes, a partially amorphous portion may remain, which is not preferable. On the other hand, if it is longer than 1500 minutes, it is inefficient and not preferable.

(Solvent salt milling)
As solvent salt milling, for example, a crude azo pigment, an inorganic salt, and an organic solvent that does not dissolve the crude azo pigment are charged into a kneader and kneaded and ground therein. As the inorganic salt, a water-soluble inorganic salt can be preferably used. For example, an inorganic salt such as sodium chloride, potassium chloride, sodium sulfate is preferably used. Moreover, it is more preferable to use an inorganic salt having an average particle size of 0.5 to 50 μm. The amount of the inorganic salt used is preferably 3 to 20 times by mass, more preferably 5 to 15 times by mass with respect to the crude azo pigment. As the organic solvent, a water-soluble organic solvent can be suitably used, and the solvent easily evaporates due to a temperature rise during kneading, so that a high boiling point solvent is preferable from the viewpoint of safety. Examples of such organic solvents include diethylene glycol, glycerin, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2- (methoxymethoxy) tanol, 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, diethylene glycol Propylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene Glycols 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 crude azo pigment. 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.

  The η-type crystal form azo pigment represented by the formula (1) of the present invention can be further subjected to a post-treatment, for example, a surface treatment with a resin, a surfactant, a dispersant and the like.

  The azo pigment represented by the above formula (1) can also be produced by the following method. That is, the heterocyclic amine represented by the following formula (2) is diazoniumized, and subsequently subjected to a coupling reaction with a compound represented by the following formula (3), whereby the azo represented by the above formula (1) is obtained. Pigments can be produced.

  The azo pigment of the present invention can be synthesized, for example, by subjecting a diazonium salt prepared by a known method to the diazo component of the above formula (2) to an azo coupling reaction with the coupling component of the above formula (3).

  The diazonium salt preparation and coupling reaction can be carried out by conventional methods.

  The diazonium salt preparation of formula (2) can be prepared, for example, in a reaction medium containing an acid (eg, hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, propionic acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc.) A conventional diazonium salt preparation method using nitric acid, nitrite or nitrosylsulfuric acid can be applied.

  More preferred examples of the acid include a case where acetic acid, propionic acid, methanesulfonic acid, phosphoric acid and sulfuric acid are used alone or in combination, and among them, phosphoric acid or a combined system of acetic acid and sulfuric acid is particularly preferred.

  Preferable examples of the reaction medium (solvent) include organic acids and inorganic acids, and phosphoric acid, sulfuric acid, acetic acid, propionic acid, and methanesulfonic acid are particularly preferable. Among these, acetic acid and / or propionic acid are preferable.

  As an example of a preferable nitrosonium ion source, use of nitrosylsulfuric acid in the above-mentioned preferable acid-containing reaction medium can stably and efficiently prepare a diazonium salt.

  0.5-50 mass times is preferable, as for the usage-amount of the solvent with respect to the diazo component of Formula (2), More preferably, it is 1-20 mass times, and 3-10 mass times is especially preferable.

  In the present invention, the diazo component of the formula (2) may be in a state of being dispersed in a solvent, or may be in a solution state depending on the kind of the diazo component.

  The amount of nitrosonium ion source used is preferably 0.95 to 5.0 equivalents, more preferably 1.00 to 3.00 equivalents, particularly 1.00 to 1.10 equivalents, relative to the diazo component. Is preferred.

  The reaction temperature is preferably -15 ° C to 30 ° C, more preferably -10 ° C to 10 ° C, and further preferably -5 ° C to 5 ° C. Less than −10 ° C. is not economical because the reaction rate is remarkably slow and the time required for the synthesis is remarkably increased, and it is preferable to synthesize at a high temperature exceeding 30 ° C. because the amount of by-products increases. Absent.

  The reaction time is preferably 30 minutes to 300 minutes, more preferably 30 minutes to 200 minutes, and still more preferably 30 minutes to 150 minutes.

  The coupling reaction can be carried out in an acidic reaction medium to a basic reaction medium, but the azo pigment of the present invention is preferably carried out in an acidic to neutral reaction medium, particularly in an acidic reaction medium. This suppresses the decomposition of the diazonium salt and can efficiently induce the azo pigment.

  As a preferable example of the reaction medium (solvent), an organic acid, an inorganic acid, or an organic solvent can be used, but an organic solvent is particularly preferable, and a solvent that does not cause a liquid separation phenomenon during the reaction and presents a uniform solution with the solvent. preferable. For example, alcoholic organic solvents such as methanol, ethanol, propanol, isopropanol, butanol, t-butyl alcohol, amyl alcohol, ketone organic solvents such as acetone, methyl ethyl ketone, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene Diol-based organic solvents such as glycol and 1,3-propanediol, ether-based organic solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol diethyl ether, tetrahydrofuran, dioxane, acetonitrile, and the like. May be a mixture of two or more.

  Preferably, the organic solvent has a polarity parameter (ET) value of 40 or more. Among them, a glycol solvent having two or more hydroxyl groups in the solvent molecule, or an alcohol solvent having 3 or less carbon atoms, preferably an alcohol solvent having 2 or less carbon atoms (for example, methanol, ethylene glycol) is used. preferable. These mixed solvents are also included.

  The amount of the solvent used is preferably 1 to 100 times by mass of the coupling component represented by the above formula (3), more preferably 1 to 50 times by mass, and still more preferably 2 to 10 times by mass.

  In the present invention, the coupling component forming the formula (1) may be dispersed in a solvent, or may be in a solution state depending on the type of coupling component.

  The amount of the coupling component used is preferably 0.95 to 5.0 equivalents, more preferably 1.00 to 3.00 equivalents, particularly 1.00 to 1.50, based on the azo coupling site. It is preferable that it is equivalent.

  The reaction temperature is preferably -30 ° C to 30 ° C, more preferably -15 ° C to 10 ° C, and further preferably -10 ° C to 5 ° C. Less than −30 ° C. is not economical because the reaction rate is remarkably slow and the time required for synthesis becomes remarkably long. In addition, synthesis at a high temperature exceeding 30 ° C. is preferable because the amount of by-products increases. Absent.

  The reaction time is preferably 30 minutes to 300 minutes, more preferably 30 minutes to 200 minutes, and still more preferably 30 minutes to 150 minutes.

  In the method for synthesizing azo pigments of the present invention, the product (crude azo pigment) obtained by these reactions may be subjected to a normal organic synthesis reaction post-treatment method and then purified or used without purification. it can.

  That is, for example, the product liberated from the reaction system can be used without being purified, or can be purified by recrystallization, salt formation, etc., alone or in combination.

  After completion of the reaction, the reaction solvent is distilled off, or it is poured into water or ice without being distilled off, and the liberated product is extracted with neutralization or without neutralization, or extracted with an organic solvent / aqueous solution. It can also be used after purification or refining by recrystallization, crystallization, salt formation or the like, either alone or in combination.

  The method for synthesizing the azo pigment of the present invention will be described in more detail.

  The method for producing an azo pigment according to the present invention includes a coupling reaction between a diazonium compound obtained by diazonium-izing a heterocyclic amine represented by the above formula (2) and a compound represented by the above formula (3). It is preferable to perform the coupling reaction after dissolving the compound of (3) in an organic solvent.

  The diazoniumation reaction of the heterocyclic amine represented by the above formula (2) can be performed, for example, in an acidic solvent such as sulfuric acid, phosphoric acid, and acetic acid with a reagent such as sodium nitrite and nitrosylsulfuric acid at a temperature of 15 ° C. or less for 10 minutes to The reaction can be carried out for about 6 hours. The coupling reaction can be performed by reacting the diazonium salt obtained by the above-described method with the compound represented by the above formula (3) at 40 ° C. or less, preferably 15 ° C. or less for about 10 minutes to 12 hours. preferable.

  The tautomerism and / or crystal polymorphism described above can be controlled by the production conditions in the coupling reaction. As a method for producing a η-type crystal, for example, it is preferable to use the method of the present invention in which a compound represented by the above formula (3) is once dissolved in an organic solvent and then a coupling reaction is performed. Examples of the organic solvent that can be used at this time include an alcohol solvent. As examples of the alcohol solvent, methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol and the like are preferable, and methanol is particularly preferable among them.

  Another method for producing an azo pigment is a polar aprotic property in a coupling reaction between a diazonium compound obtained by diazonium-izing a heterocyclic amine represented by the formula (2) and a compound represented by the formula (3). A coupling reaction is performed in the presence of a solvent.

  A η-type crystal can also be efficiently produced by a method of performing a coupling reaction in the presence of a polar aprotic solvent. Examples of polar aprotic solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetramethylurea, and mixed solvents thereof. When these solvents are used, the compound of the above formula (3) may or may not be completely dissolved in the solvent.

  Although the compound represented by the above formula (1) is obtained as a crude azo pigment (crude) by the above production method, when used as the pigment of the present invention, it is desirable to perform post-treatment. Examples of post-treatment methods include solvent salt milling, salt milling, dry milling, solvent milling, pigment particle control step by grinding treatment such as acid pasting, solvent heating treatment, resin, surfactant and dispersant. The surface treatment process by etc. is mentioned.

The compound represented by the formula (1) of the present invention is preferably subjected to solvent heat treatment and / or solvent salt milling as a post-treatment.
The method and conditions for the solvent heat treatment and solvent salt milling are the same as those described above.

(Pigment dispersion)
The pigment dispersion of the present invention is characterized by containing at least one azo pigment of the present invention. Thereby, it can be set as the pigment dispersion excellent in chromatic characteristics, durability, and dispersion stability.

  The pigment dispersion of the present invention may be aqueous or non-aqueous, but is preferably an aqueous pigment dispersion. As the aqueous liquid in which the pigment is dispersed in the aqueous pigment dispersion of the present invention, a mixture containing water as a main component and optionally adding a hydrophilic organic solvent can be used. Examples of the hydrophilic organic solvent include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol and other alcohols, ethylene glycol, diethylene glycol Polyhydric alcohols such as triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, ethylene glycol monomethyl ether, ethylene glycol mono Ethyl ether, ethylene glycol monobutyl ether, diethylene glycol mono Chill ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate triethylene glycol monoethyl ether, ethylene glycol monophenyl ether Glycol derivatives such as ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine Such as amine, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1 , 3-dimethyl-2-imidazolidinone, acetonitrile, acetone and the like.

  Further, the aqueous pigment dispersion of the present invention may contain an aqueous resin. Examples of the aqueous resin include a water-soluble resin that dissolves in water, a water-dispersible resin that disperses in water, a colloidal dispersion resin, or a mixture thereof. Specific examples of the aqueous resin include acrylic, styrene-acrylic, polyester, polyamide, polyurethane, and fluorine resins.

  Further, surfactants and dispersants may be used to improve pigment dispersion and image quality. Examples of the surfactant include anionic, nonionic, cationic and amphoteric surfactants. Any surfactant may be used, but anionic or nonionic surfactants may be used. It is preferable to use it. Examples of the anionic surfactant include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, alkyl phosphates, and polyoxyethylene alkyls. Examples thereof include ether sulfate, polyoxyethylene alkylaryl ether sulfate, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, polyoxyethylene glycerol fatty acid ester and the like.

  Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin Examples include fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, fluorine-based resins, and silicon-based materials.

  The non-aqueous pigment dispersion is obtained by dispersing the pigment represented by the formula (1) in a non-aqueous vehicle. Resins used in non-aqueous vehicles are, for example, petroleum resins, casein, shellac, rosin modified maleic resin, rosin modified phenolic resin, nitrocellulose, cellulose acetate butyrate, cyclized rubber, chlorinated rubber, oxidized rubber, hydrochloric acid rubber , Phenolic resin, alkyd resin, polyester resin, unsaturated polyester resin, amino resin, epoxy resin, vinyl resin, vinyl chloride, vinyl chloride-vinyl acetate copolymer, acrylic resin, methacrylic resin, polyurethane resin, silicone resin, fluorine resin , Drying oil, synthetic drying oil, styrene / maleic acid resin, styrene / acrylic resin, polyamide resin, polyimide resin, benzoguanamine resin, melamine resin, urea resin chlorinated polypropylene, butyral resin, vinylidene chloride resin and the like. A photocurable resin may be used as the non-aqueous vehicle.

  Examples of the solvent used in the non-aqueous vehicle include aromatic solvents such as toluene, xylene, and methoxybenzene, and acetates such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate. Solvents, propionate solvents such as ethoxyethyl propionate, alcohol solvents such as methanol and ethanol, ether solvents such as butyl cellosolve, propylene glycol monomethyl ether, diethylene glycol ethyl ether, diethylene glycol dimethyl ether, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Ketone solvents, aliphatic hydrocarbon solvents such as hexane, N, N-dimethylformamide, γ-butyrolactam, N Methyl-2-pyrrolidone, aniline, nitrogen compound-based solvent such as pyridine, a lactone-based solvents such as γ- butyrolactone, carbamic acid esters such as a mixture of 48:52 of methyl carbamate and ethyl carbamate acid.

  The pigment dispersion of the present invention can be obtained by dispersing the above azo pigment and an aqueous or non-aqueous medium using a dispersing device. Dispersing devices include simple stirrer, impeller stirring method, in-line stirring method, mill method (for example, colloid mill, ball mill, sand mill, bead mill, attritor, roll mill, jet mill, paint shaker, agitator mill, etc.), ultrasonic method Further, a high-pressure emulsification dispersion system (high-pressure homogenizer; specific commercially available devices such as gorin homogenizer, microfluidizer, DeBEE2000, etc.) can be used.

In the present invention, the volume average particle diameter of the pigment particles in the pigment dispersion is preferably 0.01 μm to 0.2 μm or less.
When the volume average particle diameter of the pigment particles in the pigment dispersion is 0.01 μm or more, it is preferable because the temporal stability of the dispersion is increased and aggregation is difficult. Further, when the volume average particle diameter of the particles is 0.2 μm or less, the optical density becomes high and the density of the printed matter becomes high, the color reproducibility of the mixed color portion such as red or green is improved, and the transparency is improved. This is preferable because it becomes high and nozzle clogging is less likely to occur when printing with an inkjet or the like.

  The volume average particle diameter of the pigment particles refers to the particle diameter of the pigment itself or the particle diameter to which the additive has adhered when an additive such as a dispersant is attached to the colorant. In the present invention, a nanotrac UPA particle size analyzer (UPA-EX150; manufactured by Nikkiso Co., Ltd.) can be used as a measuring device for the volume average particle diameter of pigment particles. The measurement can be performed according to a predetermined measurement method by placing 3 ml of the pigment dispersion in a measurement cell. As parameters input at the time of measurement, the ink viscosity is used as the viscosity, and the pigment density is used as the density of the dispersed particles.

  A more preferable volume average particle size is 20 nm or more and 250 nm or less, more preferably 30 nm or more and 200 nm or less, and most preferably 50 nm or more and 150 nm or less.

  In order to set the volume average particle diameter of the η-type crystal form azo pigment particles within the above range, for example, the following method can be used. 0.25 part of the azo pigment, 0.05 part of sodium oleate, 0.5 part of glycerin and 4.2 part of water are mixed, and 10 parts of zirconia beads having a diameter of 0.1 mm are mixed with a planetary ball mill every minute. By carrying out dispersion at 300 rotations for 1 hour and 30 minutes, the volume average particle diameter can be adjusted in the range of 0.06 to 0.10 μm (60 nm to 100 nm). Moreover, by performing dispersion for 3 hours, the volume average particle diameter can be adjusted in the range of 0.04 to 0.07 μm (40 nm to 70 nm). Moreover, by performing dispersion for 4 hours, the volume average particle diameter can be adjusted in the range of 0.03 to 0.06 μm (30 nm to 60 nm).

  The concentration of the pigment contained in the pigment dispersion of the present invention is preferably in the range of 1 to 35% by mass, and more preferably in the range of 2 to 25% by mass. If the density is less than 1% by mass, sufficient image density may not be obtained when the pigment dispersion is used alone as the ink. If the concentration exceeds 35% by mass, the dispersion stability may decrease.

  Applications of the azo pigments of the present invention include image recording materials for forming images, particularly color images. Specifically, the ink-jet recording materials described in detail below, thermal recording materials, Pressure recording material, recording material using an electrophotographic method, transfer type silver halide photosensitive material, printing ink, recording pen, etc., preferably an ink jet recording material, a thermal recording material, a recording material using an electrophotographic method, More preferred are ink jet recording materials.

  The present invention can also be applied to a solid-state image pickup device such as a CCD, a color filter for recording / reproducing a color image used in a display such as an LCD or PDP, and a dyeing solution for dyeing various fibers.

  The azo pigment of the present invention can be used in an emulsified and dispersed state and further in a solid dispersed state depending on the system used.

(Coloring composition)
The colored composition of the present invention means a colored composition containing at least one kind of the azo pigment of the present invention or a colored composition containing the pigment dispersion of the present invention. The coloring composition of the present invention can contain a medium, but when a solvent is used as the medium, it is particularly suitable as an ink for inkjet recording. The coloring composition of the present invention can be produced by using a lipophilic medium or an aqueous medium as a medium and dispersing the azo pigment of the present invention in the medium. Preferably, an aqueous medium is used. The coloring composition of the present invention includes an ink composition excluding a medium. The coloring composition of the present invention may contain other additives as necessary within a range that does not impair the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, Known additives (described in JP-A No. 2003-306623) such as a foaming agent, a viscosity modifier, a dispersant, a dispersion stabilizer, a rust inhibitor, and a chelating agent can be used. These various additives are directly added to the ink liquid in the case of water-soluble ink. In the case of oil-soluble ink, it is common to add to the dispersion after preparation of the azo pigment dispersion, but it may be added to the oil phase or water phase at the time of preparation.

〔ink〕
Next, ink will be described.
In the present invention, the azo pigment, pigment dispersion or colored composition of the present invention described above can be used as the ink. Preferably, it is prepared by mixing a water-soluble solvent, water and the like. However, if there is no particular problem, the pigment dispersion of the present invention may be used as it is.

The ink for inkjet recording in the present invention contains the azo pigment, the pigment dispersion or the coloring composition of the present invention, and the ink in the present invention can also be used as the ink for inkjet recording.
Further, the coloring composition containing the pigment of the present invention can be preferably used as an ink for inkjet recording.

[Ink for inkjet recording]
Next, the ink for ink jet recording will be described.

  As the ink for inkjet recording (hereinafter sometimes referred to as “ink”), the azo pigment, the pigment dispersion or the coloring composition of the present invention described above is used. Preferably, it is prepared by mixing a water-soluble solvent, water and the like. However, if there is no particular problem, the pigment dispersion of the present invention may be used as it is.

  The content ratio of the pigment dispersion in the ink is preferably in the range of 1 to 100% by mass, and preferably 3 to 80% by mass in consideration of the hue, color density, saturation, transparency and the like of the image formed on the recording medium. The range is particularly preferable, and the range of 3 to 60% by mass is most preferable among them.

  The pigment of the present invention is preferably contained in an amount of 0.1 to 20 parts by weight, more preferably 0.2 to 10 parts by weight, more preferably 1 to 10 parts by weight in 100 parts by weight of ink. It is more preferable to contain. Further, in the ink of the present invention, other pigments may be used in combination with the pigment of the present invention. When two or more kinds of pigments are used in combination, the total content of the pigments is preferably within the above range.

  The ink can be used not only for forming a single color image but also for forming a full color image. In order to form a full color image, a magenta color ink, a cyan color ink, and a yellow color ink can be used, and a black color ink may be further used to adjust the color tone.

  Furthermore, in the ink of the present invention, other pigments can be used simultaneously in addition to the azo pigment of the present invention. Examples of yellow pigments that can be applied include C.I. I. P. Y. -74, C.I. I. P. Y. -128, C.I. I. P. Y. -155, C.I. I. P. Y. -213, and applicable magenta pigments include C.I. I. P. V. -19, C.I. I. P. R. -122, and examples of applicable cyan pigments include C.I. I. P. B. -15: 3, C.I. I. P. B. -15: 4 can be mentioned, and apart from these, any one can be used. Applicable black materials include disazo, trisazo, and tetraazo pigments, as well as carbon black dispersions.

  As the water-soluble solvent used in the ink, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents and the like are used.

  Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, and glycerin.

  Examples of the polyhydric alcohol derivative include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, diglycerin. And ethylene oxide adducts.

  Examples of the nitrogen-containing solvent include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, and triethanolamine. Examples of alcohols include alcohols such as ethanol, isopropyl alcohol, butyl alcohol, and benzyl alcohol. Examples of the solvent include thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like. In addition, propylene carbonate, ethylene carbonate, or the like can be used.

  The water-soluble solvent used in the present invention may be used alone or in combination of two or more. The content of the water-soluble solvent is 1% by mass or more and 60% by mass or less, preferably 5% by mass or more and 40% by mass or less of the entire ink. When the amount of the water-soluble solvent in the ink is less than 1% by mass, a sufficient optical density may not be obtained. Conversely, when the amount is more than 60% by mass, the viscosity of the liquid increases. In some cases, the ejection characteristics of the ink liquid become unstable.

  The preferred physical properties of the ink in the present invention are as follows. The surface tension of the ink 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 35 mN / m or less. If the surface tension is less than 20 mN / m, liquid may overflow on the nozzle surface of the recording head, and printing may not be performed normally. On the other hand, if it exceeds 60 mN / m, the permeability to the recording medium after printing may be slow, and the drying time may be slow. The surface tension was measured under the environment of 23 ° C. and 55% RH using a Wilhelmy surface tension meter as described above.

  The viscosity of the ink is preferably from 1.2 mPa · s to 8.0 mPa · s, more preferably from 1.5 mPa · s to less than 6.0 mPa · s, still more preferably from 1.8 mPa · s to 4. It is less than 5 mPa · s. When the viscosity is greater than 8.0 mPa · s, the dischargeability may be reduced. On the other hand, when it is smaller than 1.2 mPa · s, the long-term jetting property may deteriorate.

The viscosity (including those described later) was measured using a rotational viscometer Rheomat 115 (manufactured by Contraves) at 23 ° C. and a shear rate of 1400 s ⁻¹ .

  In addition to the components described above, water is added to the ink in the range of the above-described preferable surface tension and viscosity. The amount of water added is not particularly limited, but is preferably 10% by mass to 99% by mass, and more preferably 30% by mass to 80% by mass with respect to the entire ink.

  Furthermore, if necessary, for the purpose of controlling properties such as improvement in ejection properties, cellulose derivatives such as polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose, polysaccharides and derivatives thereof, other water-soluble polymers, acrylics Polymer emulsion, polyurethane emulsion, polymer emulsion such as hydrophilic latex, hydrophilic polymer gel, cyclodextrin, macrocyclic amines, dendrimers, crown ethers, urea and its derivatives, acetamide, silicone surfactant, fluorine-based A surfactant or the like can be used.

  In order to adjust conductivity and pH, compounds of alkali metals such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino-2-methyl Nitrogen-containing compounds such as -1-propanol, alkaline earth metal compounds such as calcium hydroxide, acids such as sulfuric acid, hydrochloric acid and nitric acid, strong acid and weak alkali salts such as ammonium sulfate, and the like can be used.

  In addition, a pH buffer, an antioxidant, a fungicide, a viscosity modifier, a conductive agent, an ultraviolet absorber, and the like can be added as necessary.

[Inkjet recording method, inkjet recording apparatus, and ink tank for inkjet recording]
The ink jet recording method is a method of forming an image on the surface of a recording medium by using ink for ink jet recording and discharging the ink from the recording head to the surface of the recording medium in accordance with a recording signal.
Further, the ink jet recording apparatus includes a recording head that uses ink for ink jet recording and ejects ink (if necessary, treatment liquid) onto the surface of the recording medium. It is an apparatus to form. The ink jet recording apparatus supplies an ink tank for ink jet recording (hereinafter sometimes referred to as “ink tank”) that can supply ink to the recording head and is detachable from the main body of the ink jet recording apparatus. You may have. In this case, ink is stored in the ink tank for ink jet recording.

As the ink jet recording apparatus, a normal ink jet recording apparatus having a printing method capable of using ink for ink jet recording can be used. In addition to this, a heater for controlling the drying of the ink as necessary is provided. It may be mounted, or may be equipped with an intermediate transfer mechanism, and a mechanism for discharging (printing) ink and processing liquid onto the intermediate and then transferring it to a recording medium such as paper.
Further, an ink tank for ink jet recording is detachable from an ink jet recording apparatus equipped with a recording head, and can be used as long as it has a configuration capable of supplying ink to the recording head while attached to the ink jet recording apparatus. A known ink tank can be used.

  The ink jet recording method (apparatus) preferably employs a thermal ink jet recording method or a piezo ink jet recording method from the viewpoint of the effect of improving bleeding and intercolor bleeding. In the case of the thermal ink jet recording method, the ink is heated at the time of ejection and has a low viscosity, but the viscosity rapidly increases because the temperature of the ink is lowered on the recording medium. For this reason, there is an effect of improving bleeding and intercolor bleeding. On the other hand, in the case of the piezo ink jet method, it is possible to discharge a high-viscosity liquid, and the high-viscosity liquid can suppress spreading in the paper surface direction on the recording medium. There is an improvement effect on intercolor bleeding.

  In the ink jet recording method (apparatus), the replenishment (supply) of ink to the recording head is preferably performed from an ink tank (including a treatment liquid tank if necessary) filled with ink liquid. The ink tank is preferably of a cartridge type that can be attached to and detached from the apparatus main body, and ink can be easily replenished by exchanging the cartridge type ink tank.

[Color toner]
The content of the azo pigment in 100 parts by weight of the color toner is not particularly limited, but it is preferably 0.1 parts by weight or more, more preferably 1 to 20 parts by weight, and most preferably 2 to 10 parts by weight. preferable. As a binder resin for a color toner into which an azo pigment is introduced, all commonly used binders can be used. Examples thereof include styrene resin, acrylic resin, styrene / acrylic resin, and polyester resin.
Inorganic fine powders and organic fine particles may be externally added to the toner for the purpose of improving fluidity and controlling charging. Silica fine particles and titania fine particles whose surface is treated with an alkyl group-containing coupling agent or the like are preferably used. These have a number average primary particle size of preferably 10 to 500 nm, and more preferably 0.1 to 20% by mass in the toner.

  As the release agent, all conventionally used release agents can be used. Specific examples include olefins such as low molecular weight polypropylene, low molecular weight polyethylene, and ethylene-propylene copolymer, microcrystalline wax, carnauba wax, sazol wax, and paraffin wax. These addition amounts are preferably 1 to 5% by mass in the toner.

  The charge control agent may be added as necessary, but is preferably colorless from the viewpoint of color development. Examples thereof include those having a quaternary ammonium salt structure and those having a calixarene structure.

  As the carrier, either an uncoated carrier composed only of magnetic material particles such as iron and ferrite, or a resin-coated carrier whose magnetic material particle surface is coated with a resin or the like may be used. The average particle diameter of this carrier is preferably 30 to 150 μm in terms of volume average particle diameter.

  The image forming method to which the toner is applied is not particularly limited. For example, a method of forming a color image by repeatedly forming a color image on a photoconductor to form an image, or an image formed on a photoconductor For example, a method of sequentially transferring to an intermediate transfer member or the like, forming a color image on the intermediate transfer member or the like, and then transferring the image to an image forming member such as paper to form a color image.

[Thermal recording (transfer) material]
The heat-sensitive recording material includes an ink sheet in which the azo pigment of the present invention is coated on a support together with a binder, and an image-receiving sheet that fixes a pigment that has migrated in response to thermal energy applied from a thermal head in accordance with an image recording signal. Composed. The ink sheet can be formed by preparing an ink liquid by dispersing the azo pigment of the present invention in the form of fine particles in a solvent together with a binder, applying the ink on a support, and drying it appropriately. The amount of ink applied on the support is not particularly limited, but is preferably 30 to 1000 mg / m ² . As the preferred binder resin, ink solvent, support, and image receiving sheet, those described in JP-A-7-137466 can be preferably used.

  In order to apply the heat-sensitive recording material to a heat-sensitive recording material capable of full-color image recording, a cyan ink sheet containing a heat-diffusible cyan dye capable of forming a cyan image, and heat diffusion capable of forming a magenta image. It is preferable to form a magenta ink sheet containing a reactive magenta dye and a yellow ink sheet containing a heat diffusible yellow dye capable of forming a yellow image by sequentially coating the support. In addition, an ink sheet containing a black image forming substance may be further formed as necessary.

[Color filter]
As a color filter forming method, a pattern is first formed with a photoresist and then dyed, or disclosed in JP-A-4-163552, JP-A-4-128703, and JP-A-4-175653. Thus, there is a method of forming a pattern with a photoresist to which a dye is added. Any of these methods may be used as a method for introducing the coloring matter of the present invention into a color filter. Preferred methods are described in JP-A-4-175533 and JP-A-6-35182. The positive resist composition comprising a thermosetting resin, a quinonediazide compound, a cross-linking agent, a dye and a solvent, and after coating on a substrate, exposing through a mask and developing the exposed portion. Then, a positive resist pattern is formed, the positive resist pattern is exposed on the entire surface, and then the exposed positive resist pattern is cured, and a color filter forming method can be mentioned. In addition, a black matrix is formed according to a conventional method, and an RGB primary color system or Y, M, C complementary color system color filter can be obtained. In the case of a color filter, the amount of the azo pigment of the present invention is not limited, but is preferably 0.1 to 50% by mass.

  Regarding the thermosetting resin, quinonediazide compound, crosslinking agent, and solvent used in this case, and those used, those described in the above-mentioned patent documents can be preferably used.

  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 X-ray diffraction measurement of the η-type crystal form azo pigment uses CuKα rays in a powder X-ray diffraction measurement apparatus RINT2500 (manufactured by Rigaku Corporation) in accordance with Japanese Industrial Standard JISK0131 (general rules for X-ray diffraction analysis) The test was conducted under the following conditions.

Measuring instrument: Automatic X-ray diffractometer RINT2500 manufactured by Rigaku
X-ray tube: Cu
Tube voltage: 55KV
Tube current: 280 mA
Scanning method: 2θ / θ scan Scanning speed: 6 deg. / Min
Sampling interval: 0.100 deg.
Start angle (2θ): 5 deg.
Stop angle (2θ): 55 deg.
Divergence slit: 2 deg.
Scattering slit: 2 deg.
Receiving slit: 0.6mm
Using vertical goniometer

[Synthesis Example 1] Synthesis of η-type crystal form azo pigment (1) -1 To a mixed solvent consisting of 50 g of acetic acid and 8 g of sulfuric acid, 16.2 g of 43% nitrosylsulfuric acid solution was added over 20 minutes. This solution was cooled to 3 ° C., and 11.55 g of a compound represented by the following formula (2) was added as a powder to carry out a diazotization reaction. After stirring at the same temperature for 1 hour, excess nitrosylsulfuric acid was deactivated with 0.094 g of urea to obtain a diazonium compound preparation solution.
In this diazonium compound preparation solution, 10 g of the compound represented by the following formula (3) was added by powder at 5 ° C. or less. After completion of the addition, the temperature was raised to 20 ° C. and reacted for 2 hours to obtain an azo compound solution. In addition, precipitation of the pigment was not seen during the coupling reaction, and the azo compound solution was in a state where the obtained azo compound was completely dissolved.
A poor solvent consisting of 150 mL of methanol was prepared and stirred at 5 ° C. and 200 rpm. The above-mentioned azo compound solution was dropped into this poor solvent.
After stirring for 15 minutes as it was, the produced crystal was filtered off to obtain an azo pigment (1) -1 having a ζ-type crystal form.

  The obtained ζ-type crystal was suspended in 200 mL of water, and 28% ammonia water was added to adjust the pH to 6.0. Precipitated crystals (type ζ) were separated by filtration, thoroughly washed with water, and dried at 60 ° C. for 24 hours. The obtained crystals (ζ type) were suspended in 200 mL of acetone, heated up and stirred under reflux for 2 hours. After cooling to room temperature, the crystals were separated by filtration and thoroughly washed with acetone to obtain 19.7 g of η-type crystal form azo pigment (1) -1 represented by the following general formula (1).

The obtained ζ-type crystal form azo pigment (1) -1 was visually observed with a transmission microscope (manufactured by JEOL Ltd .: JEM-1010 electron microscope), and the length of the primary particles in the major axis direction was observed. Was about 15 μm.
When the X-ray diffraction of the ζ-type crystal form pigment (1) -1 was measured under the above conditions, the Bragg angle (2θ ± 0.2 °) was 6.6 °, 9.2 °, 10.3 °. Characteristic X-ray diffraction peaks were shown at 21.4 ° and 25.6 °.
A CuKα characteristic X-ray diffraction diagram is shown in FIG.
The obtained η-type crystal form azo pigment (1) -1 was visually observed with a transmission microscope (manufactured by JEOL Ltd .: JEM-1010 electron microscope), and the length of the primary particles in the major axis direction was observed. Was about 25 μm.
When the X-ray diffraction measurement of the η-type crystal form pigment (1) -1 was performed under the above conditions, the Bragg angle (2θ ± 0.2 °) was 4.8 °, 6.5 °, 9.2 °. , 9.7 °, 13.0 ° and 24.4 ° showed characteristic X-ray diffraction peaks.
A CuKα characteristic X-ray diffraction diagram is shown in FIG.

[Synthesis Example 2] Synthesis of η-type crystal form azo pigment (1) -2 67.5 g of the compound represented by the following (2) was dissolved in 530 mL of phosphoric acid and cooled with ice to cool the internal temperature to 3 ° C. . 26.9 g of sodium nitrite was added in portions over 15 minutes so that the internal temperature was 4 ° C. or lower. After completion of the addition, the mixture was stirred at the same temperature for 50 minutes, and 18.6 g of urea was added in portions to obtain a diazonium salt solution. Separately, 47.9 g of the compound represented by the following (3) was added to 1680 mL of methanol and completely dissolved under reflux. The internal temperature was cooled to 0 ° C. with ice cooling, and the above-described diazonium salt solution was added thereto over 30 minutes so that the internal temperature became 10 ° C. or lower. After stirring for 1 hour 30 minutes at an internal temperature of 5 ° C., the mixture was added to 1.6 L of water and stirred for 30 minutes. The precipitated crystals were separated by filtration and washed with 1 L of water. The obtained crystals were suspended in 2.5 L of water, and 28% aqueous ammonia was added to adjust the pH to 6.1. Crystals were separated by filtration, sufficiently washed with water, and dried at 60 ° C. for 24 hours to obtain a γ-type crystal form azo pigment (1) -2 represented by the following formula (1). The obtained γ-type crystal form azo pigment (1) -2 was suspended in 1.5 L of acetone, heated and stirred for 2 hours under reflux. The crystals were filtered off while hot and sufficiently washed with acetone to obtain 101.8 g of η-type crystal form azo pigment (1) -2 represented by the following formula (1).

When the obtained γ-type crystal form azo pigment (1) -2 was visually observed with a transmission microscope (manufactured by JEOL Ltd .: JEM-1010 electron microscope), the length of primary particles in the major axis direction was observed. Was about 2 μm.
When the X-ray diffraction of the γ-type crystal form pigment (1) -2 was measured under the above conditions, the Bragg angles (2θ ± 0.2 °) were 5.9 °, 7.0 ° and 8.9 °. Showed a characteristic X-ray diffraction peak.
A CuKα characteristic X-ray diffraction diagram is shown in FIG.
The obtained η-type crystal form azo pigment (1) -2 was visually observed with a transmission microscope (manufactured by JEOL Ltd .: JEM-1010 electron microscope), and the length of the primary particles in the major axis direction was observed. Was about 15 μm.
When the X-ray diffraction of the η-type crystal form pigment (1) -2 was measured under the above conditions, the Bragg angle (2θ ± 0.2 °) was 4.8 °, 6.5 °, 9.2 °. , 9.7 °, 13.0 ° and 24.4 ° showed characteristic X-ray diffraction peaks.
A CuKα characteristic X-ray diffraction diagram is shown in FIG.

[Synthesis Example 3] Synthesis of η-type crystal form azo pigment (1) -3 5.8 g of the compound represented by (2) below was dissolved in 50 mL of 12N hydrochloric acid, and cooled with ice to cool the internal temperature to -5 ° C. did. 30 mL of water in which 2.21 g of sodium nitrite was dissolved was added dropwise so that the temperature was 0 ° C. or lower. The mixture was stirred for 1 hour at an internal temperature of 0 ° C., and 0.5 g of urea was added in portions to obtain a diazonium salt solution. Separately, 5 g of the compound represented by the following (3) is added to 40 mL of acetic acid, completely dissolved at an internal temperature of 50 ° C., cooled to an internal temperature of 20 ° C., and the internal temperature of the diazonium salt solution becomes 5 ° C. or lower. Added dropwise. After completion of dropping, the temperature was raised to an internal temperature of 10 ° C., and the mixture was stirred at the same temperature for 3 hours. The precipitated crystals were separated by filtration and washed with 500 mL of water. The obtained crystals were suspended in 200 mL of water, and 28% aqueous ammonia was added to adjust the pH to 6.2. The crystals were separated by filtration, thoroughly washed with water and then dried at 80 ° C. for 12 hours. The obtained crystals were suspended in 100 mL of acetone, heated up and stirred for 2 hours under reflux. After cooling to room temperature, the crystals were filtered off and sufficiently washed with acetone to obtain 8.5 g of η-type crystal form azo pigment (1) -3 represented by the following formula (1).

The obtained η-type crystal form azo pigment (1) -3 was visually observed with a transmission microscope (manufactured by JEOL Ltd .: JEM-1010 electron microscope), and the length of the primary particles in the major axis direction was observed. Was about 20 μm.
When the X-ray diffraction of the η-type crystal form pigment (1) -3 was measured under the above conditions, the Bragg angle (2θ ± 0.2 °) was 4.8 °, 6.5 °, 9.2 °. , 9.7 °, 13.0 ° and 24.4 ° showed characteristic X-ray diffraction peaks.
A CuKα characteristic X-ray diffraction diagram is shown in FIG.

[Comparative Synthesis Example 1] Synthesis of amorphous azo compound (1) -4 16.2 g of 43% nitrosylsulfuric acid solution was added over 20 minutes to a mixed solvent consisting of 50 g of acetic acid and 8 g of sulfuric acid. This solution was cooled to 3 ° C., and 11.55 g of a compound represented by the following formula (2) was added as a powder to carry out a diazotization reaction. After stirring at the same temperature for 1 hour, excess nitrosylsulfuric acid was deactivated with 0.094 g of urea to obtain a diazonium compound preparation solution.
In this diazonium compound preparation solution, 10 g of the compound represented by the following formula (3) was added by powder at 5 ° C. or less. After completion of the addition, the temperature was raised to 20 ° C. and reacted for 2 hours to obtain an azo compound solution. In addition, precipitation of the pigment was not seen during the coupling reaction, and the azo compound solution was in a state where the obtained azo compound was completely dissolved.
A poor solvent consisting of 150 mL of water was prepared and stirred at 5 ° C. and 200 rpm. The above-mentioned azo compound solution was dropped into this poor solvent.
After stirring for 15 minutes, the precipitated solid was separated by filtration.

The obtained solid was suspended in 200 mL of water, and 28% aqueous ammonia was added to adjust the pH to 6.0. The crystals were separated by filtration and sufficiently washed with water to obtain 23.8 g (yield 94.3%) of amorphous azo compound (1) -4.
When the obtained amorphous azo compound (1) -4 was visually observed with a transmission microscope (manufactured by JEOL Ltd .: JEM-1010 electron microscope), the length of the primary particles in the major axis direction was observed. Was about 500 nm.
When measurement of the X-ray diffraction of the amorphous azo compound (1) -4 was performed under the above conditions, a characteristic X-ray diffraction peak could not be confirmed.
A CuKα characteristic X-ray diffraction diagram is shown in FIG.

[Example 1] Preparation of pigment dispersion 1 2.5 parts by mass of η-type crystal form azo pigment (1) -1 synthesized in Synthesis Example 1, 0.5 parts by mass of sodium oleate, 5 parts by mass of glycerin, water 42 parts by mass were mixed, and dispersion was performed at 300 rpm for 8 hours using a planetary ball mill together with 100 parts by mass of zirconia beads having a diameter of 0.1 mm. After completion of the dispersion, the zirconia beads were separated to obtain a yellow pigment dispersion 1 (volume average particle diameter; Mv≈120.3 nm: measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.).

[Example 2] Preparation of pigment dispersion 2 2.5 parts by mass of η-type crystal form azo pigment (1) -2 synthesized in Synthesis Example 2, 0.5 parts by mass of sodium oleate, 5 parts by mass of glycerin, water 42 parts by mass were mixed and dispersed with 300 parts by mass per minute using a planetary ball mill together with 100 parts by mass of zirconia beads having a diameter of 0.1 mm. After the completion of dispersion, zirconia beads were separated to obtain yellow pigment dispersion 2 (volume average particle diameter; Mv≈105.2 nm: measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.).

[Example 3] Preparation of pigment dispersion 3 2.5 parts by mass of η-type crystal form azo pigment (1) -3 synthesized in Synthesis Example 3, 0.5 parts by mass of sodium oleate, 5 parts by mass of glycerin, water 42 parts by mass were mixed, and dispersion was performed at 300 rpm for 5 hours using a planetary ball mill together with 100 parts by mass of zirconia beads having a diameter of 0.1 mm. After the completion of dispersion, zirconia beads were separated to obtain yellow pigment dispersion 3 (volume average particle diameter; Mv≈118.8 nm: measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.).

[Comparative Example 1] Preparation of Comparative Pigment Dispersion 1 2.5 parts by mass of amorphous azo compound (1) -4 synthesized in Comparative Synthesis Example 1, 0.5 parts by mass of sodium oleate, 5 parts by mass of glycerin Then, 42 parts by mass of water was mixed, and dispersed at 300 rpm for 8 hours using a planetary ball mill together with 100 parts by mass of zirconia beads having a diameter of 0.1 mm. After completion of the dispersion, the zirconia beads were separated to obtain a yellow comparative pigment dispersion 1 (volume average particle diameter; Mv≈207.5 nm: measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.).

Comparative Example 2 Preparation of Comparative Pigment Dispersion 2 C.I. I. Pigment Yellow 155 (Clariant's INKJET YELLOW 4G VP2532) 2.5 parts, sodium oleate 0.5 parts, glycerin 5 parts, water 42 parts are mixed, and planetary type with 100 parts of zirconia beads having a diameter of 0.1 mm Using a ball mill, dispersion was performed at 300 rpm for 3 hours. After completion of the dispersion, the zirconia beads were separated to obtain a yellow comparative pigment dispersion 2 (volume average particle diameter; Mv≈83.3 nm: measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.).

[Performance evaluation of pigment dispersion]
<Evaluation of coloring power>
The pigment dispersions obtained in the above Examples and Comparative Examples were No. 3 was applied to a photomat paper manufactured by Epson. The image density of the obtained coated material was measured using a reflection densitometer (X-Rite 938 manufactured by X-Rite), and “coloring power (OD: Optical Density)” was evaluated according to the following criteria. The case where OD was 1.4 or more was rated as ◯, the case where it was 1.2 or more and less than 1.4, Δ, and the case where it was less than 1.2, ×. The results are shown in Table 1.

<Hue evaluation>
Regarding the hue, the chromaticity of the coated product obtained above was evaluated by visually observing that the redness was small and the vividness was large, and that either one was not applicable was evaluated as x (defect). The results are shown in Table 1.

<Light fastness evaluation>
A coating with an image density of 1.0 used for hue evaluation was prepared, and a xenon light (99000 lux; in the presence of a TAC filter) was irradiated for 28 days using a fade meter, and the image density before and after the xenon irradiation was measured using a reflection densitometer. When the residual pigment ratio [(post-irradiation density / pre-irradiation density) × 100%] is 80% or more, it is evaluated as ◯, when it is 60% or more and less than 80%, and when it is less than 60%, it is evaluated as ×. did. The results are shown in Table 1.

<Filtration evaluation>
When 100 g of the azo pigment or azo compound obtained in the above synthesis examples and comparative synthesis examples is subjected to suction filtration using a Nutsche having a diameter of 12.5 cm, the time until the filtrate comes off is within 5 minutes. The case of 5 minutes or more and 10 minutes or less was evaluated as Δ, and the case of 10 minutes or more was evaluated as ×. The results are shown in Table 1.

<Dispersibility>
2.5 parts of pigment, 0.5 parts of sodium oleate, 5 parts of glycerin and 42 parts of water are mixed, and dispersed with a planetary ball mill with 100 parts of zirconia beads having a diameter of 0.1 mm for 300 rpm for 8 hours. In the evaluation, the case where the volume average particle diameter was 200 nm or less was evaluated as ◯, and the case where the volume average particle size was not evaluated was evaluated as ×. The results are shown in Table 1.

  From the above results, it was found that the azo pigment having a specific crystal structure obtained by the production method of the present invention can be filtered in a shorter time and is a highly productive pigment.

Claims (9)

The Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction is expressed by the following formula (1) having characteristic X-ray diffraction peaks at 4.8 °, 9.2 °, and 13.0 °. An azo pigment or a tautomer thereof.
Formula (1)

  The azo pigment has a Bragg angle (2θ ± 0.2 °) of 4.8 °, 6.5 °, 9.2 °, 9.7 °, 13.0 ° and 24.4 in CuKα characteristic X-ray diffraction. The azo pigment according to claim 1 or a tautomer thereof having a characteristic X-ray diffraction peak at °. (I) 6.6 °, 9.2 ° and 21.4 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction
(Ii) 4.8 °, 7.2 ° and 9.7 °
(Iii) 5.9 °, 7.0 ° and 8.9 °
The azo compound represented by the following formula (1) having a characteristic X-ray diffraction peak in any of the above or a tautomer thereof is characterized by being subjected to a solvent heat treatment,
It is represented by the following formula (1) having characteristic X-ray diffraction peaks at 4.8 °, 9.2 °, and 13.0 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction. A method for producing an azo pigment or a tautomer thereof.
Formula (1)

  The azo pigment according to claim 1, wherein the azo pigment is produced by the production method according to claim 3. An azo represented by the following formula (1) having characteristic X-ray diffraction peaks at 6.6 °, 9.2 °, and 21.4 ° of the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction Acetone solvate of the compound or a tautomer thereof.
Formula (1)

  A pigment dispersion comprising the azo pigment according to claim 1.   The pigment dispersion according to claim 6, wherein the volume average particle diameter of the pigment particles in the pigment dispersion is 0.01 μm to 0.2 μm.   A coloring composition comprising the azo pigment according to claim 1 or 2 or the pigment dispersion according to claim 6 or 7.   An ink for inkjet recording, comprising the azo pigment according to claim 1 or 2, the pigment dispersion according to claim 6 or 7, or the coloring composition according to claim 8.

Images