JP2016011374A - Method for producing self-dispersible pigment, self-dispersible pigment, ink, ink cartridge, and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a self-dispersible pigment useful as a coloring material such as ink or the like with high reaction efficiency.SOLUTION: The method for producing a self-dispersible pigment has a step of bonding a functional group including a hydrophilic group to a particle surface of a pigment by reacting a treatment agent such as a compound represented by formula or the like with the particle surface of the pigment. (Rrepresents a group having a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group substituted with at least one kind of hydrophilic group selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group and -N(R)X; Rrepresents an oxygen atom or NH; Reach independently represents a hydrogen atom or an aliphatic group; and Xrepresents a monovalent anion)

Description

  The present invention relates to a method for producing a self-dispersing pigment, a self-dispersing pigment, an ink, an ink cartridge, and an ink jet recording method.

  Self-dispersing pigments are mainly produced by chemical pigment modification techniques. For example, Patent Document 1 describes a method of obtaining a self-dispersing pigment by reacting a pigment with a diazonium salt. Patent Document 2 describes a method of obtaining a self-dispersing pigment by subjecting a carbonyl group on the surface of pigment particles to a condensation reaction with a hydrazine compound. Furthermore, Patent Document 3 describes a method of obtaining a self-dispersing pigment by reacting a pigment with a diazo compound.

Japanese National Patent Publication No. 10-510661 Special table 2012-528917 gazette JP-A-11-323229

  However, the conventional pigment modification technique is not satisfactory in that it is a production method with high reaction efficiency. That is, the production methods described in Patent Documents 1 to 3 have a problem that the reaction efficiency is low.

  Accordingly, an object of the present invention is to provide a highly reactive production method of a self-dispersing pigment useful as a coloring material such as ink. Another object of the present invention is to provide a self-dispersing pigment produced by the method for producing a self-dispersing pigment, an ink using the self-dispersing pigment, an ink cartridge, and an ink jet recording method.

  The above object is achieved by the present invention described below. That is, according to the present invention, a method for producing a self-dispersing pigment, which is a compound represented by the following general formula (1), a compound represented by the following general formula (2), and the following general formula (3) Reacting at least one treatment agent selected from the group consisting of the compounds represented by the formula (1) on the surface of the pigment particles to bond a functional group containing a hydrophilic group to the surface of the pigment particles. A featured self-dispersing pigment manufacturing method is provided.

（前記一般式（１）中、Ｒ₁は、水素原子；脂肪族基；又は脂肪族基及び芳香族基の少なくとも一方を有する基に、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換した基を表し、Ｒ₂は、酸素原子又はＮＨを表す。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (1), R ₁ is a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid; group, hydroxy group, and ^{_{-N (R 6) 3 + X}} - represents at least one hydrophilic group selected from the group consisting of is a substituent, R ₂ is, .R ₆ representing an oxygen atom or NH is Each independently represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)

（前記一般式（２）中、Ｒ₃は、脂肪族基及び芳香族基の少なくとも一方を有する基を表し、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換していてもよい。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (2), R ₃ represents a group having at least one of an aliphatic group and an aromatic group, and includes a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group, and — At least one hydrophilic group selected from the group consisting of N (R ₆ ) ₃ ⁺ X ⁻ may be substituted, each R ₆ independently represents a hydrogen atom or an aliphatic group, and X ⁻ is Represents a monovalent anion)

（前記一般式（３）中、Ｒ₄及びＲ₅は、それぞれ独立に、水素原子；脂肪族基；又は脂肪族基及び芳香族基の少なくとも一方を有する基に、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換した基を表す。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (3), R ₄ and R ₅ are each independently a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; , A phosphoric acid group, a phosphonic acid group, a hydroxy group, and a group substituted with at least one hydrophilic group selected from the group consisting of —N (R ₆ ) ₃ ⁺ X ^{—, wherein} R ₆ is independently Represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)

  ADVANTAGE OF THE INVENTION According to this invention, the highly reactive manufacturing method of the self-dispersion pigment useful as coloring materials, such as an ink, can be provided. In addition, according to the present invention, it is possible to provide a self-dispersed pigment produced by the method for producing a self-dispersed pigment, an ink using the self-dispersed pigment, an ink cartridge, and an ink jet recording method.

It is sectional drawing which shows typically one Embodiment of the ink cartridge of this invention. FIG. 2 is a diagram schematically illustrating an example of an ink jet recording apparatus used in the ink jet recording method of the present invention, in which (a) is a perspective view of a main part of the ink jet recording apparatus, and (b) is a perspective view of a head cartridge.

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. In the present invention, when an ionic group forms a salt, it may be dissociated into ions in the ink, but for convenience, it is expressed as an “ionic group”. Further, the self-dispersing pigment may be simply referred to as “pigment”. Various physical property values in this specification are values at normal temperature (25 ° C.) unless otherwise specified.

<Method for producing self-dispersing pigment>
The method for producing a self-dispersing pigment of the present invention includes a step of reacting a predetermined treating agent on the surface of the pigment particle to bond a functional group containing a hydrophilic group to the surface of the pigment particle. The treating agent is at least one selected from the group consisting of a compound represented by the following general formula (1), a compound represented by the following general formula (2), and a compound represented by the following general formula (3). is there. Hereinafter, this step is also referred to as “step (1)”.

（前記一般式（１）中、Ｒ₁は、水素原子；脂肪族基；又は脂肪族基及び芳香族基の少なくとも一方を有する基に、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換した基を表し、Ｒ₂は、酸素原子又はＮＨを表す。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (1), R ₁ is a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid; group, hydroxy group, and ^{_{-N (R 6) 3 + X}} - represents at least one hydrophilic group selected from the group consisting of is a substituent, R ₂ is, .R ₆ representing an oxygen atom or NH is Each independently represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)

（前記一般式（２）中、Ｒ₃は、脂肪族基及び芳香族基の少なくとも一方を有する基を表し、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換していてもよい。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (2), R ₃ represents a group having at least one of an aliphatic group and an aromatic group, and includes a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group, and — At least one hydrophilic group selected from the group consisting of N (R ₆ ) ₃ ⁺ X ⁻ may be substituted, each R ₆ independently represents a hydrogen atom or an aliphatic group, and X ⁻ is Represents a monovalent anion)

（前記一般式（３）中、Ｒ₄及びＲ₅は、それぞれ独立に、水素原子；脂肪族基；又は脂肪族基及び芳香族基の少なくとも一方を有する基に、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換した基を表す。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (3), R ₄ and R ₅ are each independently a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; , A phosphoric acid group, a phosphonic acid group, a hydroxy group, and a group substituted with at least one hydrophilic group selected from the group consisting of —N (R ₆ ) ₃ ⁺ X ^{—, wherein} R ₆ is independently Represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)

  According to the method for producing a self-dispersing pigment of the present invention (hereinafter, also simply referred to as “manufacturing method”), the self-dispersing pigment can be produced in a single pot at a normal temperature (25 ° C.) with high reaction efficiency without selecting a reaction apparatus or a liquid medium. Can be manufactured. In particular, since the reaction efficiency is high, it is possible to obtain a self-dispersing pigment with a high introduction amount of hydrophilic groups while reducing the amount of pigment treating agent used. Moreover, since the generation of by-products is suppressed, purification after production is easy.

The reaction efficiency in the present invention can be calculated, for example, according to the following procedure. When the self-dispersing pigment is produced, the “number of moles of hydrophilic group of the treating agent” is calculated from the number of moles of the treating agent used per 1.0 g of the pigment. The “number of moles of hydrophilic group of the treatment agent” is the number of moles of hydrophilic group of the treatment agent used per 1.0 g of the pigment. For example, when a compound having two carboxylic acid groups per molecule is used as the treating agent, it is calculated as twice the number of moles obtained using the molecular weight of this treating agent. Further, the amount of the hydrophilic group contained in the functional group on the pigment particle surface (“number of moles of hydrophilic group of pigment”, value per 1.0 g of pigment) is determined for the produced self-dispersing pigment. In the case of using a treatment agent having a hydrophilic group in the form of ester, anhydride, acid imide or the like, since these hydrophilic groups become anionic groups in the produced self-dispersing pigment, the treatment agent and pigment “ The “number of moles of hydrophilic group” is calculated as the number of moles of anionic group. The reaction efficiency (%) can be calculated based on the following formula (A) from the “number of moles of hydrophilic group of the pigment” and “number of moles of hydrophilic group of the treatment agent” obtained above.
Reaction efficiency (%)
= ("Mole number of hydrophilic group of pigment" / "Mole number of hydrophilic group of treatment agent") x 100
... (A)

  Higher reaction efficiency means that the pigment can be self-dispersed with a smaller amount of processing agent. For this reason, if the reaction efficiency is high, not only is there a merit in cost, but also the generation of impurities due to the reaction can be reduced. In addition, when the ink containing the produced self-dispersing pigment as a coloring material is applied to, for example, an ink jet recording method, it is possible to suppress deterioration in ejection characteristics due to impurities, or to improve the efficiency of purification of an aqueous dispersion containing the self-dispersing pigment. Can be improved. For this reason, it is preferable to increase the reaction efficiency as much as possible. Specifically, the reaction efficiency is preferably 10% or more, more preferably 20% or more, and particularly preferably 30% or more. The upper limit of the theoretical reaction efficiency is 100%.

  In the production method of the present invention, a diazene compound is formed by extracting a hydrogen atom from a treating agent, and a functional group is bonded to the pigment particle surface by a radical addition reaction by extracting a hydrogen atom from the diazene compound. This is a method for producing a dispersed pigment. This radical addition reaction is an oxidative radical addition reaction. As the treating agent, at least one of a compound represented by the general formula (1), a compound represented by the general formula (2), and a compound represented by the general formula (3), which is a hydrazine compound, is used.

The reaction estimation mechanism used in the production method of the present invention is shown below. Hereinafter, a part other than “H ₂ N—NH—” which is a common part of the treating agent is indicated as “R”. Further, a case where carbon black is used as a pigment and potassium hexacyanoferrate (III) is used as an oxidizing agent will be described as an example. The oxidizing species of potassium hexacyanoferrate (III) used as the oxidizing agent is Fe ³⁺ and the reducing species is Fe ²⁺ .

First, by the action of the oxidizing agent (Fe ³⁺ ), the hydrogen atom of the compound A (compound represented by the general formula (2)), which is a hydrazine compound, is withdrawn and the compound A is radically oxidized to produce a hydrazyl radical. B occurs. Next, by the action of the oxidizing agent (Fe ³⁺ ), the hydrogen atom of the hydrazyl radical B is extracted, and a compound C which is a diazene compound is generated. Furthermore, the action of the oxidizing agent (Fe ³⁺ ) causes the hydrogen atom of compound C to be withdrawn to produce a diazene radical D. The diazene radical D instantaneously causes nitrogen elimination and a radical species E is generated. The radical species E radically adds to the double bond on the carbon black particle surface, whereby R is bonded to the carbon black particle surface via the radical intermediate F, and the self-dispersing pigment G is obtained.

In the production method of the present invention, when an oxidizing agent whose valence is easily changed, such as potassium hexacyanoferrate (III), is used, an addition reaction different from the above may occur in parallel. That is, radical species E is radically added to the double bond on the carbon black particle surface to generate radical intermediate F, and at the same time, radical is captured by oxygen molecules to generate radical intermediate H. In this case, after the radical intermediate H is reduced by the action of the reducing species (Fe ²⁺ ) of the oxidizing agent, the self-dispersed pigment J which is an alcohol is obtained through the oxygen radical intermediate I.

  In each of the above reaction mechanisms, a multistage reaction including nitrogen elimination occurs, so that the reaction rate is easy to control, and the reaction itself proceeds relatively slowly. Therefore, compared with the conventional method for producing a self-dispersing pigment, according to the production method of the present invention, a self-dispersing pigment having a high introduction amount of a hydrophilic group can be obtained even when the amount of the treating agent used for the pigment is small. Can do. Moreover, although depending on the structure of the compound used as the treating agent, the functional group of the obtained self-dispersing pigment has an anionic group or a nonionic structure such as an ester group or an amide group. For this reason, the obtained self-dispersing pigment has high dispersion stability.

  In Patent Document 1 described above, a self-dispersing pigment is produced using a diazonium salt as a treating agent. However, since the diazonium salt used as a treating agent is easily decomposed, various side reactions are likely to occur. Therefore, when using a diazonium salt to obtain a self-dispersing pigment having a high introduction amount of a hydrophilic group, it is necessary to use a larger amount of the diazonium salt relative to the pigment. However, when the amount of the diazonium salt used is increased, a large amount of nitrogen gas bubbles are generated, making it difficult to increase the reaction efficiency.

  Since the treatment agent used in the production method of the present invention is chemically stable and hardly affected by the pH and temperature, the pH and temperature of the reaction system can be arbitrarily set. Specifically, the pH of the reaction system is preferably 1 to 13, more preferably 1 to 10, and particularly preferably 2 to 7. In order to increase the reaction efficiency, it is preferable that the pH of the reaction system is acidic to neutral. In a high pH range such as alkaline, the treatment agent may be decomposed. On the other hand, in the strongly acidic pH range below pH 2, the treatment agent may cause a buffering action. Furthermore, when the pH of the reaction system is less than 2, it is necessary to use a large amount of an acidic compound, so that it may be difficult to perform treatment such as purification of the self-dispersing pigment.

  Moreover, in order to control the reaction rate of the radical addition reaction, the temperature may be set to other than room temperature (25 ° C.). What is necessary is just to set temperature suitably according to the kind of processing agent. Specifically, the temperature is preferably 5 to 80 ° C, and more preferably 10 to 40 ° C. When the temperature is increased, the reaction rate increases, but side reactions occur and the reaction efficiency tends to decrease. On the other hand, when the temperature is lowered, side reactions are less likely to occur, but the reaction rate may be lowered and the reaction time may be increased.

  The production method of the present invention is usually carried out in a liquid medium. The content (% by mass) of the pigment in the liquid medium is preferably 1.0% by mass or more and 50.0% by mass or less, and 5.0% by mass or more and 40.0% by mass based on the total mass of the liquid medium. More preferably, it is% or less. If the pigment content is too high, it becomes particularly noticeable when the pigment is carbon black or the like, but the viscosity of the reaction system becomes high and stirring becomes difficult, so that the reaction efficiency may be slightly lowered. On the other hand, if the content of the pigment is too low, the contact frequency between the treatment agent and the pigment in the reaction system decreases, and the reaction efficiency may decrease slightly.

  The produced self-dispersing pigment can be used for various purposes after preferably performing a general pigment post-treatment method such as purification. Specifically, it can be a self-dispersing pigment such as a powder or pellet without a liquid medium. In this case, the liquid medium may be removed by decompression or heating using an evaporator or the like, or the liquid medium may be removed by drying using a freeze-dried method or an oven.

  Moreover, it can be set as the form of the dispersion liquid in which the self-dispersion pigment is dispersed in the liquid medium. In this case, when using only water without using an organic solvent as the liquid medium, the obtained dispersion containing the self-dispersing pigment can be used for various purposes as it is, or it can be washed with water or self-dispersed. What adjusted the content of the dispersed pigment can also be used as the final dispersion. When a liquid medium containing an organic solvent is used, the organic solvent can be removed and replaced with an aqueous liquid medium. As a method of removing the organic solvent and replacing it with an aqueous liquid medium, for example, there is a method of adding water after removing the organic solvent by reducing pressure or heating using an evaporator or the like. Furthermore, after removing the organic solvent by ultrafiltration or the like, there is also a method of repeating the operation of adding water and gradually replacing it with an aqueous liquid medium. In particular, when a dispersion liquid in which a self-dispersing pigment is dispersed in an aqueous liquid medium is used, the dispersion state can be kept more stable by ion-dissociating the hydrophilic group contained in the functional group of the self-dispersing pigment. Can do. For this reason, when the hydrophilic group contained in the functional group is anionic, it is preferable to make the dispersion alkaline. On the other hand, when the hydrophilic group contained in the functional group is cationic, it is preferable to make the dispersion acidic.

  The produced self-dispersing pigment is suitable as a coloring material for various compositions and articles such as ink, paint, plastic, rubber, paper, and carbon fiber.

(Pigment type and physical properties)
Examples of the pigment (pigment type) constituting the self-dispersing pigment include inorganic pigments such as carbon black, calcium carbonate, and titanium oxide; and organic pigments such as azo, phthalocyanine, and quinacridone. Carbon black is preferably used as the pigment because there are more reactive sites on the particle surface than other pigments and the amount of hydrophilic groups introduced can be easily increased. As carbon black, any carbon black such as furnace black, lamp black, acetylene black and channel black can be used.

  The DBP oil absorption of carbon black is preferably 50 mL / 100 g or more and 200 mL / 100 g or less. The DBP oil absorption can be measured by a method based on JIS K6221 and ASTM D 2414. These methods are methods in which dibutyl phthalate is added dropwise to 100 g of carbon black with stirring, and the amount of dibutyl phthalate added when the torque reaches a maximum is measured.

The specific surface area of the carbon black by the BET method is preferably 100 m ² / g or more and 600 m ² / g or less. The specific surface area by the BET method can be measured by a method based on JIS K6217, ASTM D 6556, or the like. In these methods, degassed carbon black is immersed in liquid nitrogen, and the amount of nitrogen adsorbed on the surface of the carbon black particles when equilibrium is reached is measured.

  The primary particle diameter of carbon black is preferably 10 nm or more and 40 nm or less. Carbon black usually exists in a state in which a plurality of primary particles are three-dimensionally connected like a bunch of grapes. The primary particle diameter means the particle diameter of carbon black (primary particles) as the minimum unit forming one pigment particle. The primary particle diameter of carbon black can be obtained by observing and measuring the particle diameter of carbon black, which is the minimum unit forming pigment particles, with a transmission or scanning electron microscope, and calculating the arithmetic average value thereof. .

The average particle size of carbon black is preferably 50 nm or more and 200 nm or less. An average particle diameter means the particle diameter of carbon black as a form which exists normally. In the present invention, the 50% cumulative value [D ₅₀ (nm)] of the volume-based particle size distribution can be measured using a dynamic light scattering type particle size distribution measuring apparatus or the like.

  The primary particle size of the organic pigment is preferably 50 nm or more and 150 nm or less. Furthermore, the average particle diameter of the organic pigment is preferably 50 nm or more and 250 nm or less. The definitions of the primary particle diameter and the average particle diameter of the organic pigment are both the same as the definitions of the primary particle diameter and the average particle diameter of carbon black.

(Processing agent)
In the production method of the present invention, the compound represented by the following general formula (1), the compound represented by the following general formula (2), and the compound represented by the following general formula (3) are selected. At least one kind is used as a pigment treating agent. The compounds represented by the general formulas (1) to (3) are all hydrazine compounds having a hydrophilic group. This hydrazine compound becomes a diazene compound by extracting a hydrogen atom. That is, a diazene structure (—N═NH) is formed by extracting a hydrogen atom from a hydrazino group (—NH—NH ₂ ). In this way, the treatment agent (hydrazine compound) passes through the diazene compound, and further draws out hydrogen atoms, whereby a functional group containing a hydrophilic group on the pigment particle surface (corresponds to a structure other than the hydrazino group of the treatment agent). Combine to self-disperse the pigment. That is, it is the diazene compound that actually self-disperses the pigment, but the pigment is self-dispersed by successive extraction of hydrogen atoms from the hydrazine compound. For this reason, in this invention, a hydrazine compound is also included in the processing agent used for the processing of a pigment. Further, hydrazine acid addition salts such as hydrazine sulfate and hydrazine hydrochloride; hydrates are also included in the treating agent used for treating the pigment. Hereinafter, the compound represented by the general formula (1), the compound represented by the general formula (2), and the compound represented by the general formula (3) will be described.

（前記一般式（１）中、Ｒ₁は、水素原子；脂肪族基；又は脂肪族基及び芳香族基の少なくとも一方を有する基に、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換した基を表し、Ｒ₂は、酸素原子又はＮＨを表す。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (1), R ₁ is a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid; group, hydroxy group, and ^{_{-N (R 6) 3 + X}} - represents at least one hydrophilic group selected from the group consisting of is a substituent, R ₂ is, .R ₆ representing an oxygen atom or NH is Each independently represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)

（前記一般式（２）中、Ｒ₃は、脂肪族基及び芳香族基の少なくとも一方を有する基を表し、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換していてもよい。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (2), R ₃ represents a group having at least one of an aliphatic group and an aromatic group, and includes a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group, and — At least one hydrophilic group selected from the group consisting of N (R ₆ ) ₃ ⁺ X ⁻ may be substituted, each R ₆ independently represents a hydrogen atom or an aliphatic group, and X ⁻ is Represents a monovalent anion)

（前記一般式（３）中、Ｒ₄及びＲ₅は、それぞれ独立に、水素原子；脂肪族基；又は脂肪族基及び芳香族基の少なくとも一方を有する基に、カルボン酸基、スルホン酸基、リン酸基、ホスホン酸基、ヒドロキシ基、及び−Ｎ（Ｒ₆）₃ ⁺Ｘ^-からなる群より選ばれる少なくとも１種の親水性基が置換した基を表す。Ｒ₆は、それぞれ独立に、水素原子又は脂肪族基を表し、Ｘ^-は、１価のアニオンを表す）

(In the general formula (3), R ₄ and R ₅ are each independently a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; , A phosphoric acid group, a phosphonic acid group, a hydroxy group, and a group substituted with at least one hydrophilic group selected from the group consisting of —N (R ₆ ) ₃ ⁺ X ^{—, wherein} R ₆ is independently Represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)

  Examples of the aliphatic group include an alkyl group, an alkenyl group, and an alkynyl group. The alkyl group, alkenyl group, and alkynyl group may be linear, branched, or cyclic. The linear and branched alkyl groups, alkenyl groups, and alkynyl groups preferably have about 1 to 12 carbon atoms. The cyclic alkyl group, alkenyl group, and alkynyl group may be either a single ring or a complex ring, and the number of elements constituting the ring is preferably about 3 to 8. Examples of the aliphatic group include linear saturated alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group; a branched chain such as an isopropyl group, an isobutyl group, and a 2-ethylhexyl group. Saturated alkyl group; alkenyl group such as ethenyl group, propenyl group and butenyl group; alkynyl group such as ethynyl group, propynyl group and butynyl group; cyclic aliphatic group such as cyclopropyl group, cyclobutyl group, cyclopentyl group and cyclohexyl group; etc. Can be mentioned.

  Examples of the aromatic group include an aryl group and a heteroaryl group. The aryl group or heteroaryl group may be either a single ring or a complex ring, and the number of elements constituting the ring is preferably about 3 to 8. Examples of the aryl group include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, and a biphenyl group. In addition, examples of the heteroaryl group include a pyridyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a thienyl group, and a thiazolyl group. Among these, a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a biphenyl group, a pyridinyl group, and the like are preferable, and a phenyl group, a naphthyl group, and the like are more preferable.

As the group having an aliphatic group and an aromatic group, each group as mentioned above is directly or -O-, -NH-, -CO-, -COO-, -CONH-, -N = N. -, - SO -, - SO 2 - may be cited bonded group through a common linker structures such. In order to increase the hydrophilicity of the functional group, it is more preferable that a group having an aliphatic group and an aromatic group has a linker structure.

  The group having at least one of an aliphatic group and an aromatic group becomes a linking group between the pigment particle surface and the hydrophilic group. For this reason, the group having at least one of an aliphatic group and an aromatic group may be any group that can self-disperse the pigment in relation to the hydrophilic group. That is, even if the structure of the linking group is large, if there are few hydrophilic groups to be substituted, the hydrophilicity of the functional group bonded to the pigment particle surface will not be high, and it will be difficult to self-disperse the pigment. Become. Therefore, when the structure of the linking group is increased, it is preferable to increase the hydrophilic group to be substituted or increase the amount of the functional group introduced on the pigment particle surface.

The hydrophilic group to be substituted with a group having at least one of an aliphatic group and an aromatic group is a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group, and —N (R ₃ ) ₃ ⁺ X. ^- is at least one selected from the group consisting of. R ₃ each independently represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion. These hydrophilic groups may be in the form of salts, esters, anhydrides, acid imides and the like as long as chemically possible.

  Among the hydrophilic groups, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a hydroxy group will be described. When a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, and a hydroxy group form a salt, at least one of the protons of each group is substituted with a cation. Examples of the cation include alkali metal ions, ammonium ions, and organic ammonium ions. Examples of the alkali metal ion include ions such as lithium, sodium and potassium. Examples of the organic ammonium ion include aliphatic amines such as mono to trialkylamines; cations and salts of aliphatic alcohol amines such as mono to trialkanolamines. In an aqueous liquid, salt may exist by being dissociated into ions, but for convenience, it is expressed as “salt”.

  When the carboxylic acid group, sulfonic acid group, phosphoric acid group, phosphonic acid group, and hydroxy group form an ester, at least one of the protons of each of these groups is an aliphatic group (an alkyl group, an alkenyl group, an alkynyl group). Group). Among them, many hydrazine compounds in which the proton of the hydrophilic group is substituted with an alkyl group are commercially available and can be suitably used because they are easily available. In addition, when using a hydrazine compound in the form of an ester or an acid imide, these hydrolysis may occur in the course of the reaction, resulting in a form of a corresponding hydrophilic group (which may be a salt or an anhydride). . Hydrolysis of an ester or an acid imide is likely to occur when heating or stirring is performed in the presence of an acid or an alkali.

Among hydrophilic ^{_{groups, -N (R 6) 3 +}} X - is described. R ₆ each independently represents a hydrogen atom or an aliphatic group. Examples of the aliphatic group include an alkyl group having about 1 to 3 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group. X ⁻ represents a monovalent anion. Examples of monovalent anions include halide ions such as fluoride ions, chloride ions and bromide ions; anions of mineral acids such as nitrate ions; and anions of organic acids such as formic acid, acetic acid and propionic acid.

  The number of hydrophilic group substitutions is theoretically equal to the number of hydrogen atoms present in a group having at least one of an aliphatic group and an aromatic group. For example, the number of substituted hydrophilic groups is 1 to 3 for a methyl group, 1 to 5 for an ethyl group, 1 to 5 for a phenyl group, 1 to 7 for a naphthyl group, 1 to 9 for an anthracenyl group, and 1 to 1 for a pyridyl group. 4. Depending on the structure, in practice, if one or two hydrophilic groups are substituted per one group having at least one of an aliphatic group and an aromatic group, the pigment may be self-dispersed. it can.

In general formula (1), R ₂ represents an oxygen atom or NH. For example, when R ₂ is an oxygen atom and R ₁ is a hydrogen atom, the compound represented by the general formula (1) has a structure represented by H ₂ N—NH—COOH. When R ₂ is NH and R ₁ is a hydrogen atom, the compound represented by the general formula (1) has a structure represented by H ₂ N—NH—CONH ₂ .

The compound represented by the general formula (2) can be expected to improve hydrophilicity due to the sulfonyl group. For this reason, R ₃ may not be substituted with a hydrophilic group. Of course, in order to further improve the dispersion stability of the self-dispersing pigment, a hydrophilic group may be substituted for R ₃ .

R ₁ in the general formula (1), the general formula (2) in R ₃ and R ₄ and R ₅ in the general formula (3), each independently, an aliphatic group, or an aliphatic group and an aromatic A group in which one or more hydrophilic groups are substituted on a group having at least one of the groups is preferable. Thereby, it becomes easy to improve reaction efficiency. R _{1 in} the general formula (1), R ₃ in the general formula (2), and R ₄ and R ₅ in the general formula (3) are each independently at least an aliphatic group or an aromatic group. A group having one group substituted with one or more hydrophilic groups is preferred. This facilitates the purification process after the production of the self-dispersing pigment. Furthermore, since the dispersion stability of the self-dispersing pigment can be further improved, a treating agent having at least one of a structure containing an arylene group and a plurality of carboxylic acid groups and a structure containing an amide bond and a phosphonic acid group is used. preferable.

  If the suitable example of a compound represented by General formula (1), General formula (2), and General formula (3) is represented with a free acid type, each compound shown to Tables 1-3 will be mentioned. In Tables 1 to 3, “Ph” means a phenylene group or a phenyl group. Of course, in the present invention, the structures of the general formula (1), the general formula (2), and the general formula (3) and the definitions thereof are included in the general formula (1) and the general formula (2). And the compound represented by General formula (3) is not limited to each compound shown to Tables 1-3. As the treating agent used in the production method of the present invention, among the compounds shown in Tables 1 to 3, the compound represented by the general formula (1) is preferable from the viewpoint of the particle size of the self-dispersing pigment. Of these, compounds 1-6 and 1-8 are more preferred. Moreover, the compound represented by General formula (2) from a viewpoint of raising reaction efficiency is preferable. Of these, compounds 2-1, 2-5, 2-6 and 2-7 are preferred.

  Commercially available reagents can be used as the compound represented by the general formula (1), the compound represented by the general formula (2), and the compound represented by the general formula (3). Moreover, when it is not marketed as a reagent, what was synthesize | combined can also be used.

(Oxidant)
In the present invention, it is preferable to produce the self-dispersing pigment by performing the above-mentioned step (1) in the presence of an oxidizing agent. The “oxidant” in the present invention means “a compound that can extract a hydrogen atom or an electron from a target compound and has an oxidation potential of +0.00 V or more”. Although the oxidizing agent can be used for improving the reaction rate, the reaction used in the production method of the present invention proceeds even without using the oxidizing agent.

  In general, when an oxidizing agent is allowed to act on a pigment, carbon atoms on the surface of the pigment particles are oxidized to form carboxylic acid groups. On the other hand, in the production method of the present invention, the action of the oxidizing agent promotes the formation of a diazene compound from the treatment agent that is a hydrazine compound, and the oxidative radical addition reaction that proceeds subsequently is promoted. Therefore, the oxidizing agent does not act directly on the pigment particle surface. This is expressed by the general formulas (1) and (2) rather than the energy (carbon-oxygen binding energy) required to oxidize the carbon atoms on the pigment particle surface to lead to the carbonyl species (C = O). This is because less energy is required to extract a hydrogen atom from the resulting compound. That is, when a hydrazine compound or a diazene compound is present, it is considered that the oxidizing agent is selectively consumed for extracting hydrogen atoms.

  Examples of the oxidizing agent that can be used in the production method of the present invention include halogen, oxo acid compound, metal oxide, metal halide compound, metal porphyrin compound, hexacyano metal acid compound, metal nitrate, hydrogen peroxide, nitric acid, and the like. Can be mentioned.

  Examples of the halogen include chlorine, bromine and iodine. Examples of the oxo acid compound include chromic acid, molybdic acid, permanganic acid, vanadic acid, bismuth acid, hypohalous acid, halous acid, halogen acid, and perhalogen acid. These oxo acid compounds may form a salt but need to have a metal. Examples of the cation forming the salt include alkali metal ions and ammonium ions. In an aqueous liquid, a salt may exist by being dissociated into ions, but for convenience, it is expressed as “salt”. Specific examples of oxo acid compounds include chromates such as potassium chromate, potassium dichromate, bis (tetrabutylammonium dichromate), pyridinium dichromate, pyridinium chlorochromate, pyridinium fluorochromate; Permanganates such as potassium acid, sodium permanganate, ammonium permanganate, silver permanganate, zinc permanganate, magnesium permanganate; vanadates such as ammonium vanadate, potassium vanadate, sodium vanadate Bismuth acid salts such as sodium bismutate and potassium bismuthate; hypochlorous acid, chlorite, perchloric acid, hypobromite, bromite, bromate, perbromate, hypoiodic acid, iodic acid , Iodic acid, periodic acid, hypofluorous acid and their salts It can be.

  Examples of the metal oxide include manganese oxide, lead oxide, copper oxide, silver oxide, osmium oxide and the like. Examples of the metal halide compound include zinc chloride, aluminum chloride, silver chloride, chromium chloride, zirconium chloride, tin chloride, cerium chloride, iron chloride, barium chloride, magnesium chloride, manganese chloride and the like.

  Examples of the metal porphyrin compound include a porphyrin compound that has a central metal and may be substituted. Specific examples include a tetrabenzoporphyrin compound, a tetraazaporphyrin compound, a phthalocyanine compound, and a naphthalocyanine compound. The central metal may be a metal whose oxidation potential of the metal porphyrin compound is +0.00 V or more. Examples of the central metal include Fe, Co, Ni, Cu, Zn, Mg, Pt, Mn, Ru, Cr, and Pd. Further, a ligand may exist in the metal, and a known ligand may be used.

  Examples of the hexacyano metal acid compound include hexacyanoferrate and hydrates thereof. Specific examples include potassium hexacyanoferrate, sodium hexacyanoferrate, ammonium hexacyanoferrate, copper hexacyanoferrate, hexacyanoferrate double salts (such as lithium and potassium hexacyanoferrate) and hydrates thereof. .

  Examples of the metal nitrate include potassium nitrate, sodium nitrate, silver nitrate, and copper nitrate.

  In addition to the oxidizing agent described above, organic peroxides, hypervalent iodine compounds, N-oxide compounds, and the like can be used as long as they fall under the definition of the “oxidizing agent” described above.

  An oxidizing agent having a higher oxidation potential is more likely to extract hydrogen atoms from the processing agent. The oxidizing agent that can be used in the present invention has an oxidation potential of +0.00 V or more. However, as a result of the study by the present inventors, the oxidation potential of the oxidizing agent is +0. It was found that the voltage is preferably 50 V or more and +1.70 V or less. Oxidizing agents having an oxidation potential within this range include iron chloride (neutral to alkaline; +0.77 V), sodium periodate (acidic; +1.20 V), manganese oxide (neutral to alkaline; +1.28 V), Examples include potassium permanganate (acidic; +1.51 V).

  General-purpose quantum chemistry calculation software Gaussian 03 Revision E.01 [structure optimization method; B3LYP / 6-31G *] (manufactured by Gaussian) was used. And the energy required in order to extract a hydrogen atom from a hydrazine compound to make a diazene compound was calculated. As a result, it was found that the energy required to extract two hydrogen atoms was + 1.00V, and the energy required to extract one hydrogen atom was + 0.50V. For these reasons, by using an oxidizing agent having an oxidation potential of +0.50 V or more, hydrogen atoms can be more efficiently extracted from the hydrazine compound, and the reaction efficiency can be improved. On the other hand, when an oxidizing agent having an oxidation potential of more than +1.70 V is used, the reaction proceeds, but the action of extracting hydrogen atoms, that is, the oxidizing action is increased, and the hydrazine compound is radicalized rapidly. In this case, since a large excess of radicals exist in the reaction system, a radical deactivation reaction (such as a homocoupling reaction between adjacent radicals) occurs. For this reason, the reaction between the pigment and the treatment agent is hindered, and it may be difficult to obtain the effect of improving the reaction efficiency by using the oxidizing agent. For this reason, the oxidation potential of the oxidizing agent is preferably +1.70 V or less. In particular, the oxidation potential of the oxidizing agent is more preferably +1.00 V or more and +1.60 V or less.

It is also preferable to use an oxidizing agent having a catalytic action. Among the oxidizing agents mentioned above, a metal halide compound, a metal porphyrin compound, or a hexacyano metal of at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Mg, Mn, Cr, and Mo Acid compounds and the like have a catalytic action. The oxidant having a catalytic action is used for extracting hydrogen atoms to become a reducing species, and then returns to the oxidizing species under the action of oxygen in the reaction system, so that it can be used again as an oxidant. Therefore, when an oxidizing agent having a catalytic action is used, the amount of the oxidizing agent used can be reduced. The oxidizing agent having a catalytic action has a metal whose valence is easily changed (a metal element capable of taking two or more oxidation states). Specific examples of the valence change of the metal include Fe (II, III), Co (II, III), Ni (II, III), Cu (0, I, II), Mg (0, II), Mn ( II, IV, VII), Cr (II, III), Mo (IV, V) and the like. The mechanism by which the catalytic action occurs will be described with specific examples. For example, in the case of an oxidizing agent having trivalent Fe (Fe (III)), the oxidizing species Fe ³⁺ (Fe (III)) is used to extract a hydrogen atom from the hydrazine compound, which is a reducing species. Fe ²⁺ (Fe (II)) is generated. Thereafter, it returns to the oxidized species Fe ³⁺ (Fe (III)) under the action of oxygen in the reaction system, so that it can be used again as an oxidizing agent.

  In the production method of the present invention, an inert gas such as nitrogen or argon can be used because its function is not impaired even when an oxidizing agent is used. This is because the oxidative radical addition reaction is carried out not by exchange of oxygen but by extraction of hydrogen atoms. As a method for introducing the inert gas into the reaction system, there are, for example, a method of flowing in from a cylinder through a tube; a method of collecting what has been collected in a balloon or the like from a needle tip, and the like.

(Liquid medium)
The production method of the present invention is usually carried out in a liquid medium. The liquid medium may be either aqueous or non-aqueous. In the production method of the present invention, the step (1) is preferably carried out in an aqueous system. When the step (1) is carried out in an aqueous system, water alone or an aqueous medium in which water is the main solvent and a protic or aprotic organic solvent is used in combination. The aqueous medium is a mixed solvent of water and an organic solvent. As the organic solvent, it is preferable to use a solvent that is miscible with or dissolved in water at an arbitrary ratio. Especially, it is preferable to use the uniform mixed solvent containing 50 mass% or more of water as an aqueous medium. As water, it is preferable to use ion-exchanged water or pure water. Moreover, when performing a process (1) by non-aqueous system, water is not used but a protic or aprotic organic solvent is used.

  A protic organic solvent is an organic solvent having a hydrogen atom (acidic hydrogen atom) bonded to oxygen or nitrogen. An aprotic organic solvent is an organic solvent having no acidic hydrogen atom. Examples of the organic solvent include alcohols; alkylene glycols; polyalkylene glycols; glycol ethers; glycol ether esters; carboxylic acid amides; ketones; ketoalcohols; cyclic ethers; A sulfur compound etc. can be mentioned.

  Examples of the liquid medium that can be suitably used in the production method of the present invention include water, tetrahydrofuran, a water / methanol mixed solvent, a water / ethanol mixed solvent, a water / ethylene glycol mixed solvent, and a water / N-methylpyrrolidone mixed solvent. , Water / tetrahydrofuran mixed solvent, water / acetone mixed solvent, and the like.

<Ink>
(Self-dispersing pigment)
The ink of the present invention contains a self-dispersing pigment as a coloring material. This self-dispersing pigment is a self-dispersing pigment produced by the production method of the present invention described above. By using a self-dispersing pigment as a coloring material, it is not necessary to add a dispersant for dispersing the pigment in the ink, or the amount of the dispersant added can be reduced. The content (% by mass) of the self-dispersing pigment in the ink is preferably 0.1% by mass or more and 15.0% by mass or less, and 1.0% by mass or more and 10.0% by mass based on the total mass of the ink. More preferably, it is% or less. The ink of the present invention may contain a dye together with a pigment for color matching.

  When the ink of the present invention is a water-based ink, it is preferable that the hydrophilic group contained in the functional group of the self-dispersing pigment is an anionic group in order to improve the optical density of the recorded image. The anionic group contained in the functional group reacts with a cation contained in the recording medium as a constituent material of the filler or ink receiving layer. For this reason, when an ink containing a self-dispersing pigment having a functional group containing an anionic group is applied to a recording medium, the pigment rapidly aggregates, so that the optical density of the image can be further improved.

  The self-dispersing pigment used as the coloring material in the ink of the present invention contains a hydrophilic group in its functional group. And when the ink of this invention is a water-based ink, it is preferable that the introduction amount of the hydrophilic group to a pigment is 0.10 mmol / g or more. If the introduction amount of the hydrophilic group to the pigment is less than 0.10 mmol / g, the dispersion stability may be slightly lowered. Further, the amount of the hydrophilic group introduced into the pigment is preferably 1.00 mmol / g or less, and more preferably 0.80 mmol / g or less.

  The introduction amount of the hydrophilic group is an index representing the amount of the hydrophilic group contained in the functional group bonded to the particle surface of the pigment directly or via another atomic group, and the amount of the hydrophilic group per 1 g of the self-dispersing pigment. Expressed in quantity (mmol). In the present invention, the introduction amount of the hydrophilic group is determined as follows. First, the structure of the functional group is specified by simultaneous differential thermal balance mass spectrometry (TG-MS), solid NMR, or the like. When the hydrophilic group contained in the functional group is an ionic group (anionic group or cationic group), the amount of ionic group introduced is determined by colloid titration. When the hydrophilic group contained in the functional group is a hydroxy group (nonionic group), the introduction amount of the nonionic group can be determined by a selective neutralization method. Then, it converts into the quantity (mmol) of the hydrophilic group per 1g of self-dispersion pigments.

  Methyl glycol chitosan or hydrochloric acid can be used for analysis of anionic groups (including hydroxy groups) by colloid titration, and polyvinyl potassium sulfate or potassium hydroxide can be used for analysis of cationic groups. Moreover, sodium hydroxide and sodium carbonate can be used for the analysis of the hydroxy group by the selective neutralization method. Here, in the titration by the selective neutralization method using sodium hydroxide, a carboxy group and a lactone group are quantified in addition to the hydroxy group. And in titration by the selective neutralization method using sodium carbonate, a carboxy group and a lactone group are quantified. For this reason, the difference of these titration values can be made into "the titration value of a hydroxy group."

(Aqueous medium)
In the ink of the present invention, water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent can be used. In the present invention, it is preferable to use an aqueous ink containing at least water as an aqueous medium. It is preferable to use deionized water (ion exchange water) as the water. The content (% by mass) of water in the ink is preferably 10.0% by mass or more and 90.0% by mass or less, preferably 50.0% by mass or more and 90.0% by mass or less, based on the total mass of the ink. It is preferable that

  The water-soluble organic solvent is not particularly limited as long as it is water-soluble, and alcohol, polyhydric alcohol, polyglycol, glycol ether, nitrogen-containing polar solvent, sulfur-containing polar solvent and the like can be used. The content (% by mass) of the water-soluble organic solvent in the ink is 5.0% by mass or more and 90.0% by mass or less, and further 10.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. It is preferable that

(Other additives)
In addition to the components described above, the ink of the present invention is a water-soluble organic substance that is solid at room temperature, such as polyhydric alcohols such as trimethylolpropane and trimethylolethane, and urea derivatives such as urea and ethyleneurea, if necessary. A compound may be contained. Furthermore, the ink of the present invention contains a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, an evaporation accelerator, a chelating agent, and a water-soluble agent as necessary. Various additives such as a functional resin may be contained.

  Examples of the surfactant include anionic, cationic and nonionic surfactants. The content (% by mass) of the surfactant in the ink is preferably 0.1% by mass or more and 5.0% by mass or less, and 0.1% by mass or more and 2.0% by mass based on the total mass of the ink. More preferably, it is% or less.

  As the surfactant, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene / polyoxypropylene block copolymer, and acetylene glycol compound are used. It is preferable. In the surfactant, the hydrophobic group tends to be adsorbed on the particle surface of the self-dispersing pigment. For this reason, the dispersion state of the self-dispersing pigment in the ink can be kept more stable. Among the surfactants, the nonionic surfactant does not have an ionic group, and therefore, it does not easily interact with the hydrophilic group of the self-dispersing pigment, but is easily adsorbed on the pigment particle surface.

  The adsorption of the surfactant to the pigment particle surface is physical adsorption. After the ink is applied to the recording medium, a part of the surfactant is detached from the pigment particle surface in the process of the ink permeating the recording medium, and a part of the surfactant is adsorbed on the pigment particle surface. It exists on the surface of and near it. Therefore, when there are too many surfactants with respect to a pigment, since the surfactant which does not detach | leave from a pigment will increase, the optical density of an image may fall a little.

  Therefore, considering the balance between the dispersion state of the self-dispersed pigment by the nonionic surfactant and the optical density of the image, the relationship between the nonionic surfactant content and the pigment content is as follows: It is preferable to do so. That is, the content (mass%) of the nonionic surfactant in the ink is preferably 0.05 times or more and 0.30 times or less as a mass ratio with respect to the pigment content (mass%). If the mass ratio is less than 0.05 times, the nonionic surfactant that adsorbs to the particle surface of the pigment is small, so that the action of stabilizing the dispersion state of the self-dispersing pigment in the ink may be slightly reduced. . On the other hand, if the mass ratio is more than 0.30, there are many nonionic surfactants that do not desorb from the pigment particle surface, so that the optical density of the recorded image may be slightly lowered.

(Ink physical properties)
When the ink of the present invention is applied to an ink jet system, it is preferable to appropriately control its physical property value. Specifically, the surface tension of the ink at 25 ° C. is preferably 10 mN / m or more and 60 mN / m or less, more preferably 20 mN / m or more and 60 mN / m or less, and 30 mN / m or more and 40 mN / m or less. It is particularly preferred that Further, the viscosity of the ink at 25 ° C. is preferably 1.0 mPa · s or more and 5.0 mPa · s or less, and more preferably 1.0 mPa · s or more and 3.0 mPa · s or less. The pH of the ink at 25 ° C. is preferably 5.0 or more and 9.0 or less.

<Ink cartridge>
The ink cartridge of the present invention includes ink and an ink storage unit that stores the ink. And the ink accommodated in this ink accommodating part is the ink of this invention demonstrated above. FIG. 1 is a cross-sectional view schematically showing an embodiment of the ink cartridge of the present invention. As shown in FIG. 1, an ink supply port 12 for supplying ink to the recording head is provided on the bottom surface of the ink cartridge. The inside of the ink cartridge is an ink storage portion for storing ink. The ink storage portion is composed of an ink storage chamber 14 and an absorber storage chamber 16, which communicate with each other via a communication port 18. The absorber housing chamber 16 communicates with the ink supply port 12. The ink storage chamber 14 stores liquid ink 20, and the absorber storage chamber 16 stores absorbers 22 and 24 that hold the ink in an impregnated state. The ink storage unit may have a form in which the entire amount of ink stored is held by an absorber without having an ink storage chamber for storing liquid ink. Further, the ink storage portion may have a form that does not have an absorber and stores the entire amount of ink in a liquid state. Further, the ink cartridge may be configured to have an ink storage portion and a recording head.

<Inkjet recording method>
The ink jet recording method of the present invention is a method of recording an image on a recording medium by discharging the ink of the present invention described above from an ink jet recording head. Examples of the method for ejecting ink include a method for imparting mechanical energy to the ink and a method for imparting thermal energy to the ink. In the present invention, it is particularly preferable to employ a method in which thermal energy is applied to the ink and the ink is ejected. Other than using the ink of the present invention, the steps of the ink jet recording method may be known.

  2A and 2B are diagrams schematically showing an example of an ink jet recording apparatus used in the ink jet recording method of the present invention. FIG. 2A is a perspective view of a main part of the ink jet recording apparatus, and FIG. 2B is a perspective view of a head cartridge. It is. The ink jet recording apparatus is provided with a conveying means (not shown) for conveying the recording medium 32 and a carriage shaft 34. A head cartridge 36 can be mounted on the carriage shaft 34. The head cartridge 36 includes recording heads 38 and 40, and is configured such that an ink cartridge 42 is set. While the head cartridge 36 is conveyed along the carriage shaft 34 in the main scanning direction, ink (not shown) is ejected from the recording heads 38 and 40 toward the recording medium 32. Then, the recording medium 32 is conveyed in the sub-scanning direction by a conveying unit (not shown), whereby an image is recorded on the recording medium 32.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited at all by the following Example, unless the summary is exceeded. In addition, what is described as “parts” and “%” with respect to the component amounts is based on mass unless otherwise specified.

<Analysis conditions>
(Oxidation potential)
A sample obtained by adding the weighed oxidizer to a supporting electrolyte (a solution of tetrabutylammonium perchlorate in acetonitrile) about 100 times the mass of the oxidizer (mass basis) was used. After deaerating the sample, an electrode of a cyclic voltammetry measuring apparatus (manufactured by BAS) was inserted into the sample. The response current was measured by sweeping the potential, and the first oxidation peak was defined as the oxidation potential of the oxidant. The measurement conditions are as follows.
・ Working electrode: Glassy carbon ・ Reference electrode: Silver electrode (Ag / Ag ⁺ )
・ Counter electrode: Platinum

<Manufacture of self-dispersing pigments>
“Mmol / g” in the following description of the production method means the number of millimoles per 1.0 g of pigment.

(Example 1)
18.0 g of pigment, 180 mL of ion-exchanged water, 1.0 mmol / g of the treating agent, and 0.5 mmol / g of the oxidizing agent were placed in a 400 mL vessel (made by IMEX) and mixed. As the pigment, carbon black (trade name “NIPEX170IQ”, manufactured by Orion Engineered Carbons) was used. In addition, Compound 1-2 (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as a treating agent. Furthermore, potassium permanganate was used as the oxidizing agent. 1 mol / L hydrochloric acid was added to adjust the pH of the liquid to 3, followed by stirring at a temperature of 25 ° C. and a rotation speed of 2,000 rpm for 48 hours. Next, the temperature was raised to 80 ° C. and stirred for 12 hours. Thereafter, the temperature of the liquid was lowered to 25 ° C., and an 8 mol / L potassium hydroxide aqueous solution was added to adjust the pH to 10 to obtain a dispersion. Using an ultrafiltration device (trade name “RP-2100”, manufactured by Ira, filter: pencil type module “SAP-0013”, manufactured by Asahi Kasei Chemicals), impurities were removed from the dispersion and purified. Purification is performed by concentrating the dispersion to 20 mL with an ultrafiltration apparatus (preparing 180 mL of filtrate), and then adding 180 mL of ion exchange water to dilute the dispersion. The electrical conductivity of the filtrate is 50 μS / It repeated by repeating until it became cm or less. After adjusting the content of the self-dispersing pigment by ultrafiltration, the coarse particles are removed by centrifugation at 5,000 rpm, and the content of the self-dispersing pigment 1 is 10.0%. 1 aqueous dispersion was obtained.

(Example 2)
An aqueous dispersion of self-dispersed pigment 2 was obtained in the same manner as in Example 1 except that 180 mL of ion-exchanged water used in the reaction was changed to 180 mL of 2-pyrrolidone.

(Example 3)
An aqueous dispersion of self-dispersed pigment 3 was obtained in the same manner as in Example 1 except that 180 mL of ion-exchanged water used in the reaction was changed to a mixed solution of 90 mL of 2-pyrrolidone and 90 mL of ion-exchanged water. .

Example 4
An aqueous dispersion of self-dispersing pigment 4 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-5 (manufactured by Sumika Techno Service).

(Example 5)
Using 4-[(chlorocarbonyl) oxy] phthalic acid-t-butyl ether as a raw material, compound 1-6 was synthesized according to the description in J. Med. Chem., 55,6762 (2012) (Non-patent Document 1). did. The NMR data of the synthesized compound 1-6 are shown below. And the aqueous dispersion of the self-dispersion pigment 5 was obtained like the above-mentioned Example 1 except having changed the processing agent into the compound 1-6.
¹ H-NMR (DMSO) δ; 7.2 (2H), 8.0 (1H)

(Example 6)
Chem. Med. Chem., 6 (7), 1258-1268 (2011) (Non-patent Document 2), P, P ′-[[(4-bromobenzyl) amino] ethylene] was synthesized. . Using synthesized P, P ′-[[(4-bromobenzyl) amino] ethylene] and 4-hydroxybenzoic acid as raw materials, according to the description of US Patent Publication No. 2007/100024 and Non-Patent Document 1. Compound 1-8 was synthesized. The NMR data of the synthesized compound 1-8 are shown below. Then, an aqueous dispersion of self-dispersed pigment 6 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-8.
¹ H-NMR (DMSO) δ; 3.5 (1H), 7.2 (2H), 8.0 (2H)

(Example 7)
An aqueous dispersion of self-dispersed pigment 7 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-13 (manufactured by Sumika Techno Service).

(Example 8)
An aqueous dispersion of self-dispersed pigment 8 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-1 (manufactured by Tokyo Chemical Industry Co., Ltd.).

Example 9
An aqueous dispersion of self-dispersed pigment 9 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-5 (manufactured by Sumika Techno Service).

(Example 10)
Compound 2-6 was synthesized according to the description of Chemistry-A European Journal, 18 (6), 1582-1585 (Non-patent Document 3) using 3- (chlorosulfonyl) phthalic acid as a raw material. The NMR data of the synthesized compound 2-6 are shown below. And the aqueous dispersion of the self-dispersion pigment 10 was obtained like the above-mentioned Example 1 except having changed the processing agent into the compound 2-6.
¹ H-NMR (DMSO) δ; 7.2 (2H), 8.0 (1H)

(Example 11)
Using P, P ′-[[(4-bromobenzyl) amino] ethylene] and 1-iodobenzoic acid synthesized according to the description of Non-Patent Document 2, as raw materials, US Patent Publication No. 2007/100024 and Compound 2-8 was synthesized according to the description in Non-Patent Document 3. The NMR data of the synthesized compound 2-8 are shown below. And the aqueous dispersion of the self-dispersion pigment 11 was obtained like the above-mentioned Example 1 except having changed the processing agent into the compound 2-8.
¹ H-NMR (DMSO) δ; 3.5 (1H), 7.2 (2H), 8.0 (2H)

(Example 12)
Compound 3-3 was synthesized according to the description of US Pat. No. 6,229,047 using di-t-butyl phosphite (manufactured by Wako Pure Chemical Industries) as a raw material. The NMR data of the synthesized compound 3-3 are shown below. Then, an aqueous dispersion of self-dispersed pigment 12 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 3-3.
¹ H-NMR (DMSO) δ; 0.95 (18H)

(Example 13)
The water of the self-dispersing pigment 13 was changed in the same manner as in Example 1 except that the treating agent was changed to Compound 3-3 and that 180 mL of ion-exchanged water used in the reaction was changed to 180 mL of 2-pyrrolidone. A dispersion was obtained.

(Example 14)
Except that the treating agent was changed to Compound 3-3, and that 180 mL of ion-exchanged water used in the reaction was changed to a mixed solution of 90 mL of 2-pyrrolidone and 90 mL of ion-exchanged water, the same as in Example 1 above. Thus, an aqueous dispersion of the self-dispersing pigment 14 was obtained.

(Example 15)
4-hydroxybenzoic acid was used as a raw material, and compound 3-9 was synthesized according to the description in Japanese Patent Application Laid-Open No. 2012-025840. The NMR data of the synthesized compound 3-9 are shown below. Then, an aqueous dispersion of self-dispersed pigment 15 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 3-9.
¹ H-NMR (DMSO) δ; 7.4 (8H)

(Example 16)
4-hydroxyphthalic acid was used as a raw material, and compound 3-11 was synthesized according to the description in Japanese Patent Application Laid-Open No. 2012-025840. The NMR data of the synthesized compound 3-11 are shown below. And the aqueous dispersion of the self-dispersion pigment 16 was obtained like the above-mentioned Example 1 except having changed the processing agent into the compound 3-11.
¹ H-NMR (DMSO) δ; 7.4 (6H)

(Example 17)
An aqueous dispersion of self-dispersed pigment 17 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the oxidizing agent was changed to potassium ferrocyanide.

(Example 18)
An aqueous dispersion of self-dispersed pigment 18 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the oxidizing agent was changed to 1.0 mmol / g potassium ferrocyanide. It was.

(Example 19)
An aqueous dispersion of self-dispersing pigment 19 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the oxidizing agent was changed to 0.2 mmol / g potassium ferrocyanide. It was.

(Example 20)
Aqueous dispersion of self-dispersing pigment 20 in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the oxidizing agent was changed to phthalocyanine iron (III) chloride (manufactured by Aldrich). Got.

(Example 21)
An aqueous dispersion of the self-dispersing pigment 21 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the oxidizing agent was not used.

(Example 22)
The water of the self-dispersing pigment 22 was changed in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the oxidizing agent was changed to 35% aqueous hydrogen peroxide (manufactured by Tokyo Chemical Industry Co., Ltd.). A dispersion was obtained.

(Example 23)
Aqueous dispersion of self-dispersed pigment 23 in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the oxidizing agent was changed to iron (III) chloride (manufactured by Tokyo Chemical Industry). A liquid was obtained.

(Example 24)
Self-dispersing pigment as described in Example 1 except that the treating agent was changed to Compound 1-6 and the pigment was changed to carbon black (trade name “HIBLACK890”, manufactured by Orion Engineered Carbons). 24 aqueous dispersions were obtained.

(Example 25)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 1-6 and the pigment was changed to carbon black (trade name “PRINTEX85”, manufactured by Orion Engineered Carbons). 25 aqueous dispersions were obtained.

(Example 26)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 1-6 and the pigment was changed to carbon black (trade name “XPB235”, manufactured by Orion Engineered Carbons). 26 aqueous dispersions were obtained.

(Example 27)
Except that the treating agent was changed to Compound 1-6 and that the pigment was changed to carbon black (trade name “Color Black FW200”, manufactured by Orion Engineered Carbons), the same as in Example 1 described above. An aqueous dispersion of dispersion pigment 27 was obtained.

(Example 28)
The treating agent was changed to Compound 1-6, and the pigment was changed to C.I. I. An aqueous dispersion of self-dispersing pigment 28 was obtained in the same manner as in Example 1 except that the pigment was changed to CI Pigment Blue 15: 3 (trade name “Heliogen Blue D 7079”, manufactured by BASF).

(Example 29)
The treating agent was changed to Compound 1-6, and the pigment was changed to C.I. I. An aqueous dispersion of the self-dispersing pigment 29 was obtained in the same manner as in Example 1 except that the pigment yellow 155 (trade name “Inkjet Yellow 4G”, manufactured by Clariant) was used.

(Example 30)
The treating agent was changed to Compound 1-6, and the pigment was changed to C.I. I. An aqueous dispersion of the self-dispersing pigment 30 was obtained in the same manner as in Example 1 except that the pigment red 122 (trade name “Hostaperm Pink E02”, manufactured by Clariant) was used.

(Example 31)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 1-6 and the pH during the reaction was adjusted to 7 using an 8 mol / L aqueous potassium hydroxide solution. 31 aqueous dispersions were obtained.

(Example 32)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 1-6 and that the pH during the reaction was adjusted to 12 using an 8 mol / L aqueous potassium hydroxide solution. 32 aqueous dispersions were obtained.

(Example 33)
An aqueous dispersion of the self-dispersing pigment 33 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the temperature during the reaction was changed to 5 ° C.

(Example 34)
An aqueous dispersion of the self-dispersing pigment 34 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 1-6 and the temperature during the reaction was changed to 60 ° C.

(Example 35)
An aqueous dispersion of self-dispersed pigment 35 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the oxidizing agent was changed to potassium ferrocyanide.

(Example 36)
An aqueous dispersion of self-dispersing pigment 36 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the oxidizing agent was changed to 1.0 mmol / g potassium ferrocyanide. It was.

(Example 37)
An aqueous dispersion of the self-dispersing pigment 37 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the oxidizing agent was changed to 0.2 mmol / g potassium ferrocyanide. It was.

(Example 38)
An aqueous dispersion of the self-dispersing pigment 38 in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the oxidizing agent was changed to phthalocyanine iron (III) chloride (manufactured by Aldrich). Got.

(Example 39)
An aqueous dispersion of self-dispersing pigment 39 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the oxidizing agent was not used.

(Example 40)
The water of the self-dispersing pigment 40 was changed in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the oxidizing agent was changed to 35% aqueous hydrogen peroxide (manufactured by Tokyo Chemical Industry Co., Ltd.). A dispersion was obtained.

(Example 41)
Aqueous dispersion of self-dispersed pigment 41 in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the oxidizing agent was changed to iron (III) chloride (manufactured by Tokyo Chemical Industry). A liquid was obtained.

(Example 42)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 2-6 and the pigment was changed to carbon black (trade name “HIBLACK890”, manufactured by Orion Engineered Carbons). 42 aqueous dispersions were obtained.

(Example 43)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 2-6 and the pigment was changed to carbon black (trade name “PRINTEX85”, manufactured by Orion Engineered Carbons). 43 aqueous dispersions were obtained.

(Example 44)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 2-6 and the pigment was changed to carbon black (trade name “XPB235”, manufactured by Orion Engineered Carbons). 44 aqueous dispersions were obtained.

(Example 45)
Except that the treating agent was changed to Compound 2-6 and that the pigment was changed to carbon black (trade name “Color Black FW200”, manufactured by Orion Engineered Carbons), self-treatment was carried out in the same manner as in Example 1 above. An aqueous dispersion of dispersion pigment 45 was obtained.

(Example 46)
The treatment agent was changed to Compound 2-6, and the pigment was changed to C.I. I. An aqueous dispersion of self-dispersing pigment 46 was obtained in the same manner as in Example 1 except that the pigment was changed to CI Pigment Blue 15: 3 (trade name “Heliogen Blue D 7079”, manufactured by BASF).

(Example 47)
The treatment agent was changed to Compound 2-6, and the pigment was changed to C.I. I. An aqueous dispersion of self-dispersing pigment 47 was obtained in the same manner as in Example 1 except that the pigment yellow was changed to Pigment Yellow 155 (trade name “Inkjet Yellow 4G”, manufactured by Clariant).

(Example 48)
The treatment agent was changed to Compound 2-6, and the pigment was changed to C.I. I. An aqueous dispersion of the self-dispersing pigment 48 was obtained in the same manner as in Example 1 except that the pigment red 122 (trade name “Hostaperm Pink E02”, manufactured by Clariant) was used.

(Example 49)
Self-dispersing pigment as in Example 1 except that the treatment agent was changed to Compound 2-6 and that the pH during the reaction was adjusted to 7 using an 8 mol / L aqueous potassium hydroxide solution. 49 aqueous dispersions were obtained.

(Example 50)
Self-dispersing pigment as in Example 1 except that the treating agent was changed to Compound 2-6 and that the pH during the reaction was adjusted to 12 using an 8 mol / L aqueous potassium hydroxide solution. 50 aqueous dispersions were obtained.

(Example 51)
An aqueous dispersion of self-dispersed pigment 51 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the temperature during the reaction was changed to 5 ° C.

(Example 52)
An aqueous dispersion of self-dispersed pigment 52 was obtained in the same manner as in Example 1 except that the treating agent was changed to Compound 2-6 and the temperature during the reaction was changed to 60 ° C.

(Comparative Example 1)
According to the description in Patent Document 1, an aqueous dispersion of comparative self-dispersion pigment 1 was obtained by the following procedure. p-Aminobenzoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) of 3.0 mmol / g and ion-exchanged water of 25 mL were placed in a 300 mL flask and kept at 5 ° C. with an ice bath. Further, after adding 5 mL of concentrated hydrochloric acid, a liquid in which 1.5 g of sodium nitrite (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 5.4 mL of ion-exchanged water was dropped, and the liquid was stirred for 2 hours while maintaining the temperature. It was. After putting 18.0 g of pigment and 200 mL of ion-exchanged water into a 400 mL vessel (manufactured by IMEX), the liquid obtained above was added and stirred at a temperature of 25 ° C. and a rotation speed of 2,000 rpm for 48 hours. As the pigment, carbon black (trade name “NIPEX170IQ”, manufactured by Orion Engineered Carbons) was used. Thereafter, 15 mL of a 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the liquid to 9. Next, purification was performed in the same manner as in Example 1 to obtain an aqueous dispersion of comparative self-dispersing pigment 1 having a content of comparative self-dispersing pigment 1 of 10.0%.

(Comparative Example 2)
An aqueous dispersion of comparative self-dispersion pigment 2 was obtained in the same manner as in Comparative Example 1 except that the treating agent was changed to p-aminophthalic acid (manufactured by Sigma-Aldrich).

(Comparative Example 3)
2- (4- (Aminophenyl) -1-hydroxyethane-1,1-diyl) bisphosphonic acid monosodium salt was synthesized according to the description in US Patent Publication No. 2007/100024. Comparative self-dispersing pigment 3 in the same manner as in Comparative Example 1 except that the treating agent was changed to 2- (4- (aminophenyl) -1-hydroxyethane-1,1-diyl) bisphosphonic acid monosodium salt. An aqueous dispersion was obtained.

(Comparative Example 4)
According to the description in Patent Document 2, an aqueous dispersion of comparative self-dispersion pigment 4 was obtained by the following procedure. 18.0 g of pigment, 200 mL of ion-exchanged water, and 1.0 mmol / g of 4-hydrazinobenzoic acid (manufactured by Tokyo Chemical Industry) are mixed, and the pH of the liquid is adjusted to 9 using ammonium hydroxide to obtain a mixed solution. It was. As the pigment, carbon black (trade name “NIPEX170IQ”, manufactured by Orion Engineered Carbons) was used. The obtained mixed solution was placed in a Pyrex (registered trademark) dish and placed in an oven, and heated at 120 ° C. for 24 hours to dry the pigment. The dried pigment was dispersed in ion exchange water and subjected to ultrasonic treatment. Subsequently, purification was performed in the same manner as in Example 1 to obtain an aqueous dispersion of comparative self-dispersing pigment 4 having a content of comparative self-dispersing pigment 4 of 10.0%.

(Comparative Example 5)
According to the description in Patent Document 3, an aqueous dispersion of comparative self-dispersion pigment 5 was obtained by the following procedure. 18.0 g of pigment, 200 mL of ion-exchanged water, and 2,2-azobis [N- (2-carboxyethyl) -2-methylpropionamide] anhydride (trade name “VA-057”, manufactured by Wako Pure Chemical Industries) 0 mmol / g was mixed and stirred at a temperature of 80 ° C. for 48 hours to obtain a reaction solution. As the pigment, carbon black (trade name “NIPEX170IQ”, manufactured by Orion Engineered Carbons) was used. After the temperature of the reaction solution was adjusted to 25 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the reaction solution to 9. Subsequently, purification was performed in the same manner as in Example 1 to obtain an aqueous dispersion of comparative self-dispersing pigment 5 having a content of comparative self-dispersing pigment 5 of 10.0%.

<Production conditions for self-dispersing pigments>
The production conditions of the self-dispersing pigment are shown in Tables 4-1 and 4-2. The meanings of the abbreviations (types of pigment) in Tables 4-1 and 4-2 are as shown below. Further, in Table 4-2, the treatment agent used in Comparative Example 3 was represented as “phosphonic acid compound”, and the treatment agent used in Comparative Example 5 was represented as “azo compound”.
・ CB1: NIPEX170IQ (manufactured by Orion Engineered Carbons)
・ CB2: HIBLACK890 (manufactured by Orion Engineered Carbons)
・ CB3: PRINTEX85 (manufactured by Orion Engineered Carbons)
・ CB4: XPB235 (manufactured by Orion Engineered Carbons)
・ CB5: Color Black FW200 (manufactured by Orion Engineered Carbons)
・ PC: Heliogen Blue D 7079 (manufactured by BASF)
・ QA: Hostaperm Pink E02 (manufactured by Clariant)
・ AZ: Inkjet Yellow 4G (manufactured by Clariant)

<Evaluation>
Evaluation shown below was performed about each manufacturing method of an Example and a comparative example. The evaluation results are shown in Tables 5-1 and 5-2. Tables 5-1 and 5-2 also show the structure of the functional group bonded to the particle surface of the self-dispersing pigment. In Tables 5-1 and 5-2, “Ph” means a phenylene group or a phenyl group.

(Reaction efficiency)
After 80.0 g of 0.1 mol / L hydrochloric acid is added to 20.0 g of the aqueous dispersion of the self-dispersing pigment to precipitate the self-dispersing pigment, the supernatant liquid is obtained by centrifuging at 5,000 rpm for 30 minutes. The removal operation was repeated twice to obtain a sample. The obtained sample was placed in an oven at a temperature of 60 ° C. and dried for 18 hours to obtain a dried product. The obtained dried product was ground in an agate mortar, and 0.5 g of the solid product was weighed. After adding 30.0 g of 0.1 mol / L sodium hydroxide aqueous solution to this solid and stirring for 1 day, it was centrifuged for 60 minutes at a rotational speed of 80,000 rpm using a centrifuge (manufactured by Beckman Coulter). The supernatant liquid was collected. The collected liquid was subjected to back titration to determine the amount of hydrophilic group contained in the functional group on the pigment particle surface (“number of moles of hydrophilic group of pigment”, value per 1.0 g of pigment). For the reverse titration, a potentiometric titrator (trade name “AT-510”, manufactured by Kyoto Electronics Industry Co., Ltd.) was used, and the dropping amount and time were automatically controlled. Further, 0.1 mol / L hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a titrant. When producing the self-dispersing pigment, the “number of moles of hydrophilic group of the treating agent” was calculated from the number of moles of the treating agent used per 1.0 g of the pigment. The “number of moles of hydrophilic group of the treatment agent” is the number of moles of hydrophilic group of the treatment agent used per 1.0 g of the pigment. For example, when a compound having two carboxylic acid groups is used as the treating agent, it is calculated as twice the number of moles obtained using the molecular weight of the treating agent.

The reaction efficiency (%) was calculated based on the following formula (A) from the “number of moles of hydrophilic group of the pigment” and “number of moles of hydrophilic group of the treatment agent” obtained above. In addition, the value of reaction efficiency was shown as an integer value rounded off to the first decimal place for convenience.
Reaction efficiency (%)
= ("Mole number of hydrophilic group of pigment" / "Mole number of hydrophilic group of treatment agent") x 100
... (A)

From the calculated reaction efficiency value, the reaction efficiency was evaluated according to the following evaluation criteria. In the present invention, “C” is an unacceptable level and “AA”, “A”, and “B” are acceptable levels according to the following evaluation criteria.
AA: The reaction efficiency was 30% or more.
A: The reaction efficiency was 20% or more and less than 30%.
B: The reaction efficiency was 10% or more and less than 20%.
C: The reaction efficiency was less than 10%.

<Recording images>
Using the aqueous dispersion of the self-dispersion pigment, the following components (unit:%) were mixed, stirred thoroughly, and then with a membrane filter (trade name “HDCII filter”, manufactured by Pall) having a pore size of 1.2 μm. Each ink was prepared by pressure filtration. “Acetyleneol E100” is a trade name of a nonionic surfactant (manufactured by Kawaken Fine Chemicals).
-Aqueous dispersion of self-dispersing pigment: 30.0%
・ Glycerin: 15.0%
・ Triethylene glycol: 5.0%
-Acetylenol E100: 0.2%
・ Ion exchange water: 49.8%
Each of the prepared inks was filled in an ink cartridge and mounted on an ink jet recording apparatus (trade name “PIXUS MP480”, manufactured by Canon Inc.) that discharges ink from the recording head by the action of thermal energy. Using this inkjet recording apparatus, a solid image was recorded on a recording medium (plain paper, trade name “PB PAPER GF-500”, manufactured by Canon Inc.). As a result, when the self-dispersed pigment produced in the example was used, a comparative self-dispersed pigment produced by using the same pigment type and functional group structure as in Comparative Example 1 as in the example to be compared was used. Compared with the case where the image was high, the optical density was high and a high-quality image could be recorded.

Claims (10)

A method for producing a self-dispersing pigment, comprising:
At least one treatment agent selected from the group consisting of a compound represented by the following general formula (1), a compound represented by the following general formula (2), and a compound represented by the following general formula (3), A method for producing a self-dispersing pigment, comprising a step of reacting a pigment particle surface with a functional group containing a hydrophilic group on the pigment particle surface.

(In the general formula (1), R ₁ is a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid; group, hydroxy group, and ^{_{-N (R 6) 3 + X}} - represents at least one hydrophilic group selected from the group consisting of is a substituent, R ₂ is, .R ₆ representing an oxygen atom or NH is Each independently represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)

(In the general formula (2), R ₃ represents a group having at least one of an aliphatic group and an aromatic group, and includes a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a hydroxy group, and — At least one hydrophilic group selected from the group consisting of N (R ₆ ) ₃ ⁺ X ⁻ may be substituted, each R ₆ independently represents a hydrogen atom or an aliphatic group, and X ⁻ is Represents a monovalent anion)

(In the general formula (3), R ₄ and R ₅ are each independently a hydrogen atom; an aliphatic group; or a group having at least one of an aliphatic group and an aromatic group; , A phosphoric acid group, a phosphonic acid group, a hydroxy group, and a group substituted with at least one hydrophilic group selected from the group consisting of —N (R ₆ ) ₃ ⁺ X ^{—, wherein} R ₆ is independently Represents a hydrogen atom or an aliphatic group, and X ⁻ represents a monovalent anion)   The method for producing a self-dispersing pigment according to claim 1, wherein the treating agent has at least one of a structure containing an arylene group and a plurality of carboxylic acid groups, and a structure containing an amide bond and a phosphonic acid group.   The method for producing a self-dispersing pigment according to claim 1 or 2, wherein the step is performed in the presence of an oxidizing agent.   The method for producing a self-dispersing pigment according to claim 3, wherein an oxidation potential of the oxidizing agent is +0.50 V or more and +1.70 V or less.   The oxidizing agent is a metal halide compound, a metal porphyrin compound, or a hexacyano metal acid compound of at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Mg, Mn, Cr, and Mo. The manufacturing method of the self-dispersion pigment of Claim 3 or 4.   The method for producing a self-dispersing pigment according to any one of claims 1 to 5, wherein the step is performed in an aqueous system.   A self-dispersing pigment produced by the production method according to any one of claims 1 to 6. An ink containing a self-dispersing pigment,
The ink according to claim 7, wherein the self-dispersing pigment is the self-dispersing pigment according to claim 7. An ink cartridge comprising ink and an ink containing portion for containing the ink,
An ink cartridge, wherein the ink is the ink according to claim 8. An inkjet recording method for recording an image on a recording medium by discharging ink from an inkjet recording head,
An ink jet recording method, wherein the ink is the ink according to claim 8.

Images