JP6860330B2 - Self-dispersing pigment manufacturing method, ink manufacturing method, and inkjet recording method - Google Patents

Description

The present invention relates to a method for producing a self-dispersing pigment, a method of manufacturing i ink, 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 for obtaining a self-dispersing pigment by reacting a pigment with a diazonium salt. Further, Patent Document 2 describes a method for obtaining a self-dispersing pigment by condensing a carbonyl group on the particle surface of the pigment with a hydrazine compound. Further, Patent Documents 3 and 4 describe methods for obtaining a self-dispersing pigment by reacting a pigment with an azo compound.

Special Table No. 10-510861 Special Table 2012-528917 Japanese Unexamined Patent Publication No. 11-323229 JP-A-2002-226726

However, the conventional pigment modification technique is not satisfied with the production method having high reaction efficiency. That is, the production methods described in Patent Documents 1 to 4 have a problem that the reaction efficiency is low.

Therefore, an object of the present invention is to provide a method for producing a self-dispersing pigment useful as a coloring material such as ink with high reaction efficiency. Another object of the present invention, the manufactured by the manufacturing method of the self-dispersion pigment was used a superior self-dispersing Pigment dispersibility, a method of manufacturing ink excellent in storage stability, and an inkjet recording method Is to provide.

The above object is achieved by the following invention. That is, according to the present invention, a method for producing a self-dispersing pigment is selected from the group consisting of compounds represented by the compound represented by Mono及beauty following formula by the following general formula (1) (2) at least one treatment agent that is reacted on the particle surface of the pigment, method for producing a self-dispersing pigment comprising the step of bonding the functional groups on the particle surface of the pigment is provided comprising a hydrophilic group Will be done.

（前記一般式（１）中、Ｒ_１及びＲ_２は、それぞれ独立に、アルキル基、アルコキシ基、アリール基、アリールオキシ基、又はＯＭを表し、Ｍは、それぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムを表す。Ｒ_３は、脂肪族基、芳香族基、又は脂肪族基と芳香族基とが直接結合若しくはリンカー構造を介して結合した基に、カルボン酸基、スルホン酸基、リン酸基、及びホスホン酸基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）

(In the general formula (1), R ₁ and R ₂ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₃ is an aliphatic group , an aromatic group, or a carboxylic acid group, a sulfonic acid, or a group in which an aliphatic group and an aromatic group are directly bonded or bonded via a linker structure. Represents a group substituted with at least one hydrophilic group selected from the group consisting of a group, a phosphate group, and a phosphonic acid group)

（前記一般式（２）中、Ｒ_４及びＲ_５は、それぞれ独立に、アルキル基、アルコキシ基、アリール基、アリールオキシ基、又はＯＭを表し、Ｍは、それぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムを表す。Ｒ_６は、脂肪族基、芳香族基、又は脂肪族基と芳香族基とが直接結合若しくはリンカー構造を介して結合した基に、カルボン酸基、スルホン酸基、リン酸基、及びホスホン酸基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）

(In the general formula (2), R ₄ and R ₅ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₆ is an aliphatic group , an aromatic group, or a carboxylic acid group, a sulfonic acid, or a group in which an aliphatic group and an aromatic group are directly bonded or bonded via a linker structure. Represents a group substituted with at least one hydrophilic group selected from the group consisting of a group, a phosphate group, and a phosphonic acid group)

According to the present invention, it is possible to provide a method for producing a self-dispersing pigment useful as a coloring material such as ink with high reaction efficiency. Further, according to the present invention, this is produced by the manufacturing method of the self-dispersion pigment was used a superior self-dispersing Pigment dispersibility, a method of manufacturing ink excellent in storage stability, and an inkjet recording method can do.

It is sectional drawing which shows typically one Embodiment of the ink cartridge of this invention. It is a figure which shows typically an example of the inkjet recording apparatus used in the inkjet recording method of this invention, (a) is the perspective view of the main part of the inkjet recording apparatus, (b) is the perspective view of the head cartridge.

Hereinafter, embodiments of the present invention will be described, 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 and exist in the ink, but for convenience, it is expressed as an "ionic group". In addition, the self-dispersing pigment may be simply referred to as "pigment". Various physical property values in the present specification are values at room temperature (25 ° C.) unless otherwise specified.

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

（前記一般式（１）中、Ｒ₁及びＲ₂は、それぞれ独立に、アルキル基、アルコキシ基、アリール基、アリールオキシ基、又はＯＭを表し、Ｍは、それぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムを表す。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に、カルボン酸基、スルホン酸基、リン酸基、及びホスホン酸基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）

(In the general formula (1), R ₁ and R ₂ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₃ is selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group in a group having at least one of an aliphatic group and an aromatic group. Represents a group substituted with at least one hydrophilic group)

（前記一般式（２）中、Ｒ₄及びＲ₅は、それぞれ独立に、アルキル基、アルコキシ基、アリール基、アリールオキシ基、又はＯＭを表し、Ｍは、それぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムを表す。Ｒ₆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、及びホスホン酸基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）

(In the general formula (2), R ₄ and R ₅ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₆ is selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group in a group having at least one of an aliphatic group and an aromatic group. Represents a group substituted with at least one hydrophilic group)

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 one pot with high reaction efficiency even at room temperature (25 ° C.) regardless of the reaction apparatus or liquid medium. Can be manufactured. In particular, since the reaction efficiency is high, it is possible to obtain a self-dispersing pigment having a high amount of functional groups introduced while reducing the amount of the pigment treatment agent used. In addition, 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 producing the self-dispersing pigment, the "number of moles of hydrophilic groups of the treatment agent" is calculated from the number of moles of the treatment agent used per 1.0 g of the pigment. The "number of moles of hydrophilic groups of the treatment agent" is the number of moles of hydrophilic groups 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 treatment agent, the molecular weight of the treatment agent is used to calculate as twice the number of moles obtained. Further, for the produced self-dispersing pigment, the amount of hydrophilic groups contained in the functional groups on the particle surface of the pigment (“the number of moles of hydrophilic groups of the pigment”, the value per 1.0 g of the pigment) is determined. When a treatment agent having hydrophilic groups in the form of an anhydride or the like is used, these hydrophilic groups are anionic groups in the produced self-dispersing pigment, so that the "number of moles of hydrophilic groups" of the treatment agent and pigment is used. Is calculated as the number of moles of anionic groups. Then, the reaction efficiency (%) can be calculated from the "number of moles of hydrophilic groups of the pigment" and "number of moles of hydrophilic groups of the treatment agent" obtained above based on the following formula (A).
Reaction efficiency (%)
= ("Number of moles of hydrophilic groups of pigment" / "Number of moles of hydrophilic groups of treatment agent") x 100
... (A)

The higher the reaction efficiency, the more the pigment can be self-dispersed with a smaller amount of treatment agent. Therefore, if the reaction efficiency is high, not only is there a cost advantage, but also the generation of impurities due to the reaction can be reduced, and the purification efficiency of the aqueous dispersion containing the self-dispersing pigment can be improved. .. Further, when an ink containing the produced self-dispersing pigment as a coloring material is applied to, for example, an inkjet recording method, it is possible to suppress deterioration of ejection characteristics due to impurities and improve the efficiency of purification of an aqueous dispersion containing the self-dispersing pigment. Can be improved. Therefore, 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 theoretical upper limit of reaction efficiency is 100%.

The reaction estimation mechanism used in the production method of the present invention is shown below. Hereinafter, a case where the compound represented by the general formula (1) is used as the treatment agent and carbon black is used as the pigment will be described as an example.

First, the action of heat decomposes compound A (compound represented by the general formula (1)) to produce radical species B, nitrogen gas C, and radical species D. Next, the radical species D radically adds to the aromatic carbon atom on the surface of the carbon black particles, so that R ₃ is bonded to the surface of the carbon black particles to obtain the self-dispersing pigment E. Any method may be used to decompose compound A. For example, energy such as heat, electron extraction action by an oxidizing agent, and reaction under acidic conditions can be mentioned. In the reaction under acidic conditions, one of the nitrogen atoms constituting the azo bond is cationized and the electrons are biased to promote the elimination of nitrogen gas.

When the compound represented by the general formula (2) is used, first, the oxygen atom of the compound represented by the general formula (2) is extracted, and the compound has the same structure as the compound represented by the general formula (1). Is generated. After that, the reaction proceeds in the same manner as in the case of the compound represented by the general formula (1), and a self-dispersing pigment is obtained.

The pigment treatment agent used in the production method of the present invention is a compound having an asymmetric structure centered on an azo group. This treatment agent is considered to have a function of binding a functional group containing a hydrophilic group to the particle surface of the pigment by a multi-step reaction of decomposition, production of active species, and addition reaction. In particular, since the structure of −P (= O) − has high electron attraction, the nitrogen atoms of the azo group (−N = N−) and the azoxy group (−N (= O) = N−) are biased in electrons. Occurs. It is considered that this bias promotes the activity and increases the reaction efficiency. In the reaction mechanism used in the production method of the present invention, the reaction rate is easily controlled and the reaction proceeds relatively slowly. Therefore, as compared with the conventional method for producing an autocovariant pigment, according to the production method of the present invention, even if the amount of the treatment agent used for the pigment is small, the amount of functional groups introduced is high and the amount of functional groups introduced is high. A uniform amount of self-dispersing pigment can be obtained. Further, since the treatment agent has high hydrophilicity and the amount of functional groups introduced can be made uniform, the obtained self-dispersing pigment has a small average particle size and uniform particle characteristics. Further, the functional group of the obtained self-dispersing pigment has a structure in which a hydrophilic group is substituted with a group having at least one of an aliphatic group and an aromatic group. Therefore, the obtained self-dispersing pigment has high dispersion stability. Whether or not the amount of functional groups introduced is uniform can be determined using the zeta potential (full width at half maximum) as an index. This point will be described later.

In Patent Document 1 described above, a self-dispersing pigment is produced using a diazonium salt as a treatment agent. However, the diazonium salt used as a treatment agent is easily decomposed by the influence of alkali or a temperature exceeding room temperature (25 ° C.). Decomposition of diazonium salts in the reaction system produces various decomposition products. Therefore, various side reactions such as the reaction between the decomposed product and the liquid medium or oxygen, the reaction between the decomposed products, and the side reactions other than these are likely to occur. Therefore, when using a diazonium salt to obtain a self-dispersing pigment having a high amount of functional groups introduced, it is necessary to use a large amount of the diazonium salt with respect to the pigment. However, when the amount of the diazonium salt used is increased, many bubbles of nitrogen gas are generated, so that it is difficult to increase the reaction efficiency.

Further, conventionally, it is known to use a compound having an asymmetric structure as an azo initiator that can obtain high radical generation efficiency when synthesizing a polymer or protein. This point is described in, for example, POLYMER, 23, 1982, 630-631. However, it is not envisioned that these azo initiators will be used for pigment autocovariance. Even when these azo initiators are used, the water dispersibility of the obtained pigment is insufficient.

Since the treatment agent used in the production method of the present invention is chemically stable and is not easily affected by 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 9. 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 by a reaction that does not go through the elimination of nitrogen gas. On the other hand, in a strongly acidic pH range of less than pH 1.5 or less than pH 2, the treatment agent may cause a buffering action. Further, when the pH of the reaction system is less than 1.5 or less than 2, the solubility of the treatment agent tends to be low, the reaction efficiency is lowered, and it is necessary to use a large amount of acidic compounds. Processing such as purification of self-dispersing pigments may be difficult.

Further, in order to control the reaction rate of the radical addition reaction, the temperature may be set to a temperature other than room temperature (25 ° C.). The temperature may be appropriately set according to the type of the treatment agent. Specifically, the temperature is preferably 30 to 100 ° C, more preferably 50 to 80 ° C. When the temperature is raised, the reaction rate increases, but side reactions are likely to occur, and the reaction efficiency may 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 lengthened.

The production method of the present invention is usually carried out in a liquid medium. The content (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. It is more preferably less than or equal to%. If the content of the pigment is too high, it becomes particularly remarkable 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 pigment content is too low, the contact frequency between the treatment agent and the pigment in the reaction system decreases, and the reaction efficiency decreases slightly, or the viscosity of the reaction system becomes too low, causing turbulence due to stirring. It may occur and the efficiency of stirring tends to be low.

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 in the form of powder or pellets in which no liquid medium is present. 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 frozen drying method or an oven.

Further, it can be in the form of a dispersion liquid in which the self-dispersing pigment is dispersed in the liquid medium. In this case, when only water is used as the liquid medium without using an organic solvent, the obtained dispersion liquid containing the self-dispersing pigment can be used as it is for various purposes, and can be washed with water or self-cleaning. The final dispersion may be prepared by adjusting the content of the dispersion pigment. When a liquid medium containing an organic solvent is used, the organic solvent can be removed. As a method for removing the organic solvent, for example, there is a method of adding water after removing the organic solvent by depressurizing or heating using an evaporator or the like. Further, there is also a method of repeating the operation of adding water after removing the organic solvent by ultrafiltration or the like. In particular, in the case of a dispersion in which the self-dispersing pigment is dispersed in an aqueous liquid medium, the dispersed state can be kept more stable by ion-dissociating the hydrophilic groups contained in the functional groups of the self-dispersing pigment. Can be done. Since the hydrophilic group contained in the functional group is anionic, it is preferable to make the dispersion liquid alkaline.

The self-dispersing pigments produced are suitable as coloring materials for various compositions and articles such as inks, paints, plastics, rubbers, papers, and carbon fibers.

(Pigment type and physical property value)
As the pigment (pigment type) constituting the self-dispersing pigment, for example, an inorganic pigment such as carbon black, calcium carbonate or titanium oxide; an organic pigment such as azo, phthalocyanine or quinacridone can be used. Among them, it is preferable to use carbon black or an organic pigment, and in particular, carbon black is used as a pigment because it has more reactive sites on the particle surface than other pigments and it is easy to increase the amount of functional groups introduced. Is preferable. As the 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. Among them, 120 mL / 100 g or more and 170 mL / 100 g or less is more preferable, and 120 mL / 100 g or more and 150 mL / 100 g or less is particularly preferable. The amount of DBP oil absorbed can be measured by a method conforming to JIS K6221 or ASTM D 2414. These methods are methods in which dibutyl phthalate is added dropwise to 100 g of carbon black under stirring, and the amount of dibutyl phthalate added at the time when the torque is maximized is measured.

The specific surface area of 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 conforming to JIS K6217, ASTM D6556, or the like. These methods are methods in which degassed carbon black is immersed in liquid nitrogen, and the amount of nitrogen adsorbed on the particle surface of the carbon black when equilibrium is reached is measured.

The primary particle size 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 size means the particle size of carbon black (primary particles), which is the smallest unit that forms one pigment particle. The primary particle size of carbon black can be measured by observing about 100 points of the particle size of carbon black, which is the smallest unit for forming pigment particles, with a transmission type or scanning electron microscope, and can be obtained as an arithmetic mean value thereof. ..

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

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

(Processing agent)
In the production method of the present invention, at least one of the compound represented by the following general formula (1) and the compound represented by the following general formula (2) is used as a pigment treatment agent. The compounds represented by the general formulas (1) and (2) are all azo compounds having a hydrophilic group. These compounds undergo decomposition, generation of active species, and addition reaction _{to bond functional groups containing hydrophilic groups (groups represented by R 3} and R ₆ ) to the particle surface of the pigment to self-disperse the pigment. It is a compound that can be converted. Hereinafter, the compound represented by the general formula (1) and the compound represented by the general formula (2) will be described respectively.

（前記一般式（１）中、Ｒ₁及びＲ₂は、それぞれ独立に、アルキル基、アルコキシ基、アリール基、アリールオキシ基、又はＯＭを表し、Ｍは、それぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムを表す。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に、カルボン酸基、スルホン酸基、リン酸基、及びホスホン酸基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）

(In the general formula (1), R ₁ and R ₂ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₃ is selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group in a group having at least one of an aliphatic group and an aromatic group. Represents a group substituted with at least one hydrophilic group)

（前記一般式（２）中、Ｒ₄及びＲ₅は、それぞれ独立に、アルキル基、アルコキシ基、アリール基、アリールオキシ基、又はＯＭを表し、Ｍは、それぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムを表す。Ｒ₆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、及びホスホン酸基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）

(In the general formula (2), R ₄ and R ₅ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₆ is selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group in a group having at least one of an aliphatic group and an aromatic group. Represents a group substituted with at least one hydrophilic group)

The alkyl group may be either a straight chain or a branched chain. The alkyl groups of the straight chain and the branched chain preferably have about 1 to 12 carbon atoms. Examples of the alkyl group include linear saturated alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group and hexyl group; branched chain saturation such as isopropyl group, isobutyl group and 2-ethylhexyl group. Alkyl groups and the like can be mentioned. The alkyl group may have a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom; or a substituent such as a hydroxy group.

The alkoxy group may be either a straight chain or a branched chain. The linear and branched alkoxy groups preferably have about 1 to 12 carbon atoms. Examples of the alkoxy group include linear saturated alkoxy groups such as methoxy group, ethoxy group, propyl group, butoxy group, pentyloxy group and hexyloxy group; branched chains such as isopropyl group, isobutoxy group and 2-ethylhexyloxy group. Saturated alkoxy groups and the like can be mentioned. The alkoxy group may have a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom; or a substituent such as a hydroxy group.

The aryl group may be either a monocyclic ring or a complex ring. The number of elements constituting the monocyclic ring and the complex 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, a biphenyl group and the like. Among these, a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group and the like are preferable, and a phenyl group, a naphthyl group and the like are more preferable.

The aryloxy group may be either a monocyclic ring or a complex ring. The number of elements constituting the monocyclic ring and the complex ring is preferably about 3 to 8. Examples of the aryloxy group include a phenoxy group, a naphthyloxy group, an anthrasenyloxy group, a phenanthrenyloxy group, a biphenyloxy group and the like. Among these, a phenoxy group, a naphthyloxy group, an anthracenyloxy group, a phenanthrenyloxy group and the like are preferable, and a phenoxy group, a naphthyloxy group and the like are more preferable.

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 alkyl group, alkenyl group, and alkynyl group of the linear and branched chains preferably have about 1 to 12 carbon atoms. The cyclic alkyl group, alkenyl group, and alkynyl group may be either a monocyclic 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 a linear saturated alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group and a hexyl group; and 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, butenyl group; alkynyl group such as ethynyl group, propynyl group, butynyl group; cyclic aliphatic group such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group; etc. Can be mentioned. The aliphatic group may have a substituent such as a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom; a hydroxy group;

Examples of the aromatic group include an aryl group and a heteroaryl group. The aryl group or heteroaryl group may be either a monocyclic 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, a biphenyl group and the like. 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 the group having an aliphatic group and an aromatic group has a linker structure.

A group having at least one of an aliphatic group and an aromatic group serves as a linking group between the particle surface of the pigment and the hydrophilic group. Therefore, the group having at least one of an aliphatic group and an aromatic group may be any group capable of self-dispersing the pigment in relation to the hydrophilic group. That is, if the structure of the linking group is large but the number of hydrophilic groups to be substituted is small, the hydrophilicity of the functional group bonded to the particle surface of the pigment does not increase, and it is difficult to self-disperse the pigment. Become. Therefore, when increasing the structure of the linking group, it is preferable to increase the number of hydrophilic groups to be substituted or increase the amount of functional groups introduced on the particle surface of the pigment.

The hydrophilic group substituting a group having at least one of an aliphatic group and an aromatic group is at least one selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. These hydrophilic groups may be in the form of salts, anhydrides, etc., wherever chemically possible.

The hydrophilic groups such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group will be described. When a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group form a salt, at least one of the protons of each of these groups 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 of aliphatic alcohol amines such as mono to trialkanolamines, and salts thereof. In an aqueous liquid, the salt may be dissociated into ions and exist, but for convenience, it is referred to as "salt".

The number of substitutions of a hydrophilic group 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 substitutions of hydrophilic groups is 1 to 3 for methyl groups, 1 to 5 for ethyl groups, 1 to 5 for phenyl groups, 1 to 7 for naphthyl groups, 1 to 9 for anthrasenyl groups, and 1 to 1 for pyridyl groups. It is 4. Although it depends on the structure, in reality, the pigment can be self-dispersed by substituting one or two hydrophilic groups for each group having at least one of an aliphatic group and an aromatic group. it can.

_{R 3} in the general formula (1) _{and R 6} in the general formula (2) may have 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. preferable.

Preferable examples of the compounds represented by the general formulas (1) and (2) include the compounds shown in Tables 1 and 2. _{R 3} in the general formula (1) _{and R 6} in the general formula (2) are functional groups containing hydrophilic groups such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. In some cases, compounds having such functional groups are represented by the free acid type. In addition, "Ph" in Tables 1 and 2 means a phenylene group or a phenyl group. Of course, in the present invention, the compounds represented by the general formulas (1) and the general formula (2) are as long as they are included in the structures and definitions of the general formulas (1) and (2). It is not limited to each compound shown in Tables 1 and 2.

As the compound represented by the general formula (1) and the compound represented by the general formula (2), a commercially available reagent can be used. In addition, when it is not commercially available as a reagent, a synthesized reagent can also be used.

(Oxidant)
In the present invention, the above-mentioned step (1) can be performed in the presence of an oxidizing agent to produce a self-dispersing pigment. Although the oxidizing agent can be used to improve the reaction rate, the reaction used in the production method of the present invention proceeds without using the oxidizing agent.

Generally, when an oxidizing agent is allowed to act on a pigment, carbon atoms on the particle surface of the pigment are oxidized to form a carboxylic acid group. On the other hand, in the production method of the present invention, the treatment agent is selectively oxidized by the oxidizing agent to promote the progress of the addition reaction of the functional group to the pigment. Therefore, the oxidizing agent does not act directly on the particle surface of the pigment.

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, hexacyanometallic acid compound, metal glass oxide, hydrogen peroxide, nitric acid and the like. Can be mentioned.

Examples of halogen include chlorine, bromine, iodine and the like. Examples of the oxo acid compound include chromic acid, molybdenum acid, permanganic acid, vanadic acid, bismuth acid, hypochlorous acid, hypohalogenic acid, halogen acid, perhalogen acid and the like. These oxoacid compounds may form salts, but are required to have a metal. Examples of the cation forming the salt include alkali metal ions and ammonium ions. In an aqueous liquid, the salt may be dissociated into ions and exist, but for convenience, it is referred to as "salt". Specific examples of the oxo acid compound include chromates such as potassium chromate, potassium dichromate, bis (tetrabutylammonium) dichromate, pyridinium dichromate, pyridinium chlorochromate, and pyridinium fluorochromate; permanganese. Permanganates such as potassium acid, sodium permanganate, ammonium permanganate, silver permanganate, zinc permanganate, magnesium permanganate; vanadates such as ammonium vanadate, potassium vanadate, sodium vanadate Bismates such as sodium bismuthate and potassium bismuthate; hypochlorous acid, chloric acid, perchloric acid, hypobromic acid, bromine acid, bromic acid, perbromic acid, hypoiodic acid, chlorous acid , Iodic acid, periodic acid, hypochlorous acid and salts thereof.

Examples of the metal oxide include manganese oxide, lead oxide, copper oxide, silver oxide, and osmium oxide. 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 and manganese chloride.

Examples of the metal porphyrin compound include a porphyrin compound having a central metal and which may be substituted. Specific examples thereof include tetrabenzoporphyrin compounds, tetraazaporphyrin compounds, phthalocyanine compounds, and naphthalocyanine compounds. Examples of the central metal include Fe, Co, Ni, Cu, Zn, Mg, Pt, Mn, Ru, Cr, and Pd. Further, a ligand may be present in the metal, and a known ligand may be used.

Examples of the hexacyanometallic acid compound include hexacyanoferrate and hydrates thereof. Specific examples thereof include potassium hexacyanoferrate, sodium hexacyanoferrate, ammonium hexacyanoferrate, copper hexacyanoferrate, double hexacyanoferrate (lithium hexacyanoferrate, potassium, etc.) and hydrates thereof. ..

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

In addition to the above-mentioned oxidizing agents, for example, organic peroxides, hypervalent iodine compounds, N-oxide compounds and the like can also be used as the oxidizing agents.

Further, an oxidizing agent having a catalytic action can also be used. Among the oxidizing agents listed above, at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Mg, Mn, Cr, and Mo, a halogenated metal compound, a metal porphyrin compound, or a hexacyanometal. Acid compounds and the like have a catalytic action. The oxidizing agent having a catalytic action can be used again as an oxidizing agent because the oxidizing agent used for oxidizing the treatment agent becomes a reducing species and then returns to the oxidized species by the action of oxygen in the reaction system. .. Therefore, the amount of the oxidizing agent used can be reduced by using the oxidizing agent having a catalytic action. The oxidizing agent having a catalytic action has a metal whose valence is easily changed (a metal element capable of taking two or more oxidizing states). Specific examples of metal valence changes 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), etc. The mechanism by which the catalytic action occurs will be described with reference to 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 ^{oxidize the treatment agent, and the reducing species Fe 2+} ( Fe (II)) is produced. After that, it can be used as an oxidizing agent again by returning to ^{Fe 3+} (Fe (III)), which is an oxidizing species, under the action of oxygen in the reaction system.

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

(Liquid medium)
The production method of the present invention is usually carried out in an aqueous liquid medium. As the aqueous liquid medium, water alone or an aqueous medium in which water is used as a main solvent and a protic or aprotic organic solvent is used in combination can be used. 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 mixed or dissolved in water at an arbitrary ratio. Among them, it is preferable to use a uniform mixed solvent containing 50% by mass or more of water as the aqueous medium. As the water, it is preferable to use ion-exchanged water or pure water.

The protic organic solvent is an organic solvent having a hydrogen atom (acidic hydrogen atom) bonded to oxygen or nitrogen. The aprotic organic solvent is an organic solvent that does not have an acidic hydrogen atom. Examples of the organic solvent include alcohols; alkylene glycols; polyalkylene glycols; glycol ethers; glycol ether esters; carboxylic acid amides; ketones; keto alcohols; cyclic ethers; nitrogen-containing compounds; Sulfur compounds and the like can be mentioned.

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

<Ink>
(Autocovariant pigment)
The ink of the present invention contains a self-dispersing pigment as a coloring material. The self-dispersing pigment is a self-dispersing pigment produced by the above-mentioned production method of the present invention. By using the 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 (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. It is more preferably less than or equal to%. The ink of the present invention may contain a dye or the like together with a pigment for color matching or the like.

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

The amount of functional groups introduced is an index showing the amount of functional groups bonded directly to the particle surface of the pigment or via other atomic groups, and is represented by the amount of functional groups (mmol) per 1 g of the self-dispersing pigment. .. In the present invention, the amount of the functional group introduced is determined as follows. First, the structure of the functional group is specified by simultaneous differential thermal balance mass spectrometry (TG-MS) or solid-state NMR. Then, the amount of the hydrophilic group introduced is determined by the colloid titration method. Methyl glycol chitosan or hydrochloric acid can be used for the analysis of hydrophilic groups by the colloid titration method. After that, when one functional group contains a plurality of hydrophilic groups, the amount of the hydrophilic groups introduced is divided by the number of the hydrophilic groups, and then the amount of the functional groups (mmol) per 1 g of the self-dispersing pigment is calculated. Convert.

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

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. Above all, it is preferable to use a water-soluble organic solvent having a vapor pressure at 25 ° C. lower than that of water. The content (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. Is preferable.

(Other additives)
The ink of the present invention is solid at room temperature such as polyhydric alcohols such as trimethylolpropane and trimethylolethane; urea derivatives such as urea, ethyleneurea and hydantoins; and sugars, if necessary, in addition to the above-mentioned components. May contain a water-soluble organic compound of. Further, the ink of the present invention can be used as a surfactant, a pH adjuster, a rust preventive, a preservative, a fungicide, an antioxidant, a reduction inhibitor, an evaporation accelerator, a chelating agent, and a water-soluble agent, if necessary. Various additives such as a sex resin may be contained.

Examples of the surfactant include anionic, cationic and nonionic surfactants. The content (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. It is more preferably less than or equal to%.

As the surfactant, a nonionic surfactant such as polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene / polyoxypropylene block copolymer, and acetylene glycol-based compound is used. Is preferable. The hydrophobic group of the surfactant is easily adsorbed on the particle surface of the self-dispersing pigment. Therefore, the dispersed 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, so that it is difficult to interact with the functional group of the self-dispersing pigment, but it is easily adsorbed on the particle surface of the pigment.

(Physical characteristics of ink)
When the ink of the present invention is applied to an inkjet method, it is preferable to appropriately control its physical characteristics. Specifically, the surface tension of the ink at 25 ° C. is preferably 10 mN / m or more and 60 mN / m or less, and more preferably 20 mN / m or more and 60 mN / m or less. Among them, it is preferably 30 mN / m or more and 50 mN / m or less, and particularly preferably 30 mN / m or more and 40 mN / m or less. The viscosity of the ink at 25 ° C. is preferably 1.0 mPa · s or more and 10.0 mPa · s or less, more preferably 1.0 mPa · s or more and 5.0 mPa · s or less, and 1.0 mPa. -It is particularly preferable that the content is 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 an ink and an ink accommodating portion for accommodating the ink. The ink contained in the ink accommodating portion is the ink of the present invention described 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 accommodating portion for accommodating ink. The ink accommodating portion is composed of an ink accommodating chamber 14 and an absorber accommodating chamber 16, and these are communicated with each other through a communication port 18. Further, the absorber accommodating chamber 16 communicates with the ink supply port 12. The ink storage chamber 14 contains the liquid ink 20, and the absorber storage chamber 16 contains the absorbers 22 and 24 that hold the ink in an impregnated state. The ink accommodating portion may not have an ink accommodating chamber for accommodating liquid ink, and may have a form in which the entire amount of ink contained is held by an absorber. Further, the ink accommodating portion may have a form in which the entire amount of ink is accommodating in a liquid state without having an absorber. Further, the ink cartridge may be in a form configured to have an ink accommodating portion and a recording head.

<Inkjet recording method>
The inkjet recording method of the present invention is a method of ejecting the ink of the present invention described above from an inkjet recording head to record an image on a recording medium. Examples of the method of ejecting ink include a method of applying mechanical energy to the ink and a method of applying thermal energy to the ink. In the present invention, it is particularly preferable to adopt a method of applying thermal energy to the ink to eject the ink. Other than using the ink of the present invention, the steps of the inkjet recording method may be known.

FIG. 2 is a diagram schematically showing an example of an inkjet recording device used in the inkjet recording method of the present invention, (a) is a perspective view of a main part of the inkjet recording device, and (b) is a perspective view of a head cartridge. Is. The inkjet recording device is provided with a transport means (not shown) for transporting the recording medium 32 and a carriage shaft 34. The head cartridge 36 can be mounted on the carriage shaft 34. The head cartridge 36 includes recording heads 38 and 40, and is configured so that the 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 the conveying means (not shown), so that the image is recorded on the recording medium 32.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded. In addition, what is described as "part" and "%" about the component amount is based on mass unless otherwise specified.

<Manufacturing of self-dispersing pigments>
"Mmol / g" in the description of the following production method means the number of millimoles (mmol) per 1.0 g of pigment.

(Example 1)
A mixture was obtained by mixing 30.0 g (166 mmol) of p-aminobenzoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 3 mol / L hydrochloric acid (304 mL). To the obtained mixture, 12 mL of an aqueous solution containing 11.8 g (171 mmol) of sodium nitrite was added dropwise while maintaining the temperature at 5 ° C. or lower, and the mixture was stirred for 1 hour to obtain a mixture 1. On the other hand, 18.2 g (166 mmol) of dimethyl phosphite (manufactured by Tokyo Chemical Industry Co., Ltd.), 90.6 g (1079 mmol) of sodium hydrogen carbonate, and water (815 mL) were mixed to obtain a mixture 2. The mixture 1 obtained above was added to the mixture 2 while being kept at 5 ° C. or lower. Then, the mixture was obtained by stirring overnight while keeping the temperature below 5 ° C. The resulting mixture was extracted with 4 L of a mixed solvent of ethyl acetate / isopropyl alcohol = 7: 1. The organic layer was dried over anhydrous magnesium sulfate and then concentrated under reduced pressure to give 16.9 g of compound 1-1, which is a dark red oil. The NMR data of the obtained compound 1-1 is shown below.
^{1 1} H-NMR (DMSO); 3.5 (6H), 7.7 (2H), 8.3 (2H), 11.6 (1H)

18.0 g of pigment, 180 mL of ion-exchanged water, and 1.0 mmol / g of treatment agent were placed in a vessel (manufactured by Imex) having a capacity of 400 mL and mixed. As the pigment, carbon black (trade name "Toka Black # 8300", manufactured by Tokai Carbon) was used. Compound 1-1 was used as the treatment agent. An 8 mol / L potassium hydroxide aqueous solution was added to adjust the pH of the liquid to 6, and the mixture was stirred at a temperature of 60 ° C. and a rotation speed of 2,000 rpm for 48 hours. Then, an 8 mol / L potassium hydroxide aqueous solution was added to adjust the pH of the liquid to 10, and a dispersion was obtained. An ultrafiltration device (trade name "RP-2100", manufactured by Islay, filter: pencil type module "SAP-0013", manufactured by Asahi Kasei Chemicals) was used to remove impurities from the dispersion and purify. For purification, the dispersion is concentrated to 20 mL with an ultrafiltration device (180 mL of the filtrate is separated), and then 180 mL of ion-exchanged water is added to dilute the dispersion, and the operation is repeated four times to obtain the electrical conductivity of the filtrate. This was performed by confirming that the value was 50 μS / cm or less. After ultrafiltration to adjust the content of the self-dispersing pigment, centrifugation is performed at a rotation speed of 5,000 rpm for 30 minutes to remove coarse particles, and the content of the self-dispersing pigment 1 is 10.0%. An aqueous dispersion of the dispersion pigment 1 was obtained.

(Example 2)
Compound 1-2 was synthesized in the same manner as in Compound 1-1 described above, except that dimethyl phosphite was changed to diethyl phosphite (manufactured by Tokyo Chemical Industry Co., Ltd.) at 166 mmol. The NMR data of the synthesized compound 1-2 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 2 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-2.
^{1 1} H-NMR (DMSO); 1.3 (6H), 4.2 (4H), 7.6 (2H), 8.5 (2H), 11.1 (1H)

(Example 3)
Compounds 1-3 were synthesized in the same manner as in Compound 1-1 described above, except that dimethylphosphite was changed to 166 mmol of diphenylphosphite (manufactured by Tokyo Chemical Industry Co., Ltd.). The NMR data of the synthesized compounds 1-3 are shown below. Further, an aqueous dispersion of the self-dispersing pigment 3 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-3.
^{1 1} H-NMR (DMSO); 7.1-7.2 (10H), 7.4 (2H), 8.2 (2H), 10.9 (1H)

(Example 4)
Similar to Compound 1-1 described above, except that p-aminobenzoic acid was changed to 4-aminophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol, and dimethylphosphite was changed to diethylphosphite (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol. Compounds 1-4 were synthesized. The NMR data of the synthesized compounds 1-4 are shown below. Further, an aqueous dispersion of the self-dispersing pigment 4 was obtained in the same manner as in Example 1 described above, except that the treating agent was changed to Compound 1-4.
^{1 1} H-NMR (DMSO); 1.7 (6H), 4.0 (4H), 7.8 (1H), 8.2 (2H), 11.2 (1H), 11.3 (2H)

(Example 5)
Similar to Compound 1-1 described above, except that p-aminobenzoic acid was changed to 4-aminophthalic acid (manufactured by Tokyo Chemical Industry) at 166 mmol, and dimethylphosphite was changed to diphenylphosphite (manufactured by Tokyo Chemical Industry) at 166 mmol. Compound 1-5 was synthesized. The NMR data of the synthesized compound 1-5 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 5 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-5.
^{1 1} H-NMR (DMSO); 7.1-7.3 (10H), 7.4 (2H), 8.1 (2H), 11.2 (1H), 11.4 (1H)

(Example 6)
P-aminobenzoic acid was changed to 4-aminophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol, and dimethylphosphite was changed to ethyl methylphosphinate (manufactured by Kishida Chemical Co., Ltd.) to 166 mmol. Compounds 1-6 were synthesized in the same manner. The NMR data of the synthesized compound 1-6 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 6 was obtained in the same manner as in Example 1 described above, except that the treating agent was changed to Compound 1-6.
^{1 1} H-NMR (DMSO); 1.3 (3H), 1.5 (3H), 4.2 (2H), 7.9 (1H), 8.1-8.2 (2H), 11.1 (1H) 11.3 (1H)

(Example 7)
Compound 1-1 described above, except that p-aminobenzoic acid was changed to 4-aminophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol, and dimethylphosphite was changed to phosphorous acid (manufactured by Wako Pure Chemical Industries, Ltd.) to 166 mmol. Compound 1-7 was synthesized in the same manner as in the above. The NMR data of the synthesized compound 1-7 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 7 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-7.
^{1 1} H-NMR (DMSO); 7.9 (1H), 8.3-8.4 (2H), 11.2 (1H), 11.4 (1H), 11.7 (2H, broad * phosphorus atom) (Assigned to the proton of the hydroxy group bonded to)

(Example 8)
Compound 1-1 described above, except that p-aminobenzoic acid was changed to 5-aminoisophthalic acid (manufactured by Tokyo Chemical Industry) at 166 mmol, and dimethylphosphite was changed to diethylphosphite (manufactured by Tokyo Chemical Industry) at 166 mmol. Compound 1-8 was synthesized in the same manner as in the above. The NMR data of the synthesized compound 1-8 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 8 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-8.
^{1 1} H-NMR (DMSO); 1.2 (6H), 4.1 (4H), 8.1 (2H), 8.7 (1H), 10.911.2 (2H, Broad)

(Example 9)
With the above-mentioned compound 1-1, except that p-aminobenzoic acid was changed to 4-aminosalicylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol, and dimethylphosphite was changed to diethylphosphite (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol. Compounds 1-9 were synthesized in the same manner. The NMR data of the synthesized compound 1-9 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 9 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-9.
^{1 1} H-NMR (DMSO); 1.2 (6H), 4.4 (4H), 7.1-7.2 (2H), 7.9 (1H), 11.1 (1H) [hydroxy group Proton could not be confirmed]

(Example 10)
Similar to Compound 1-1 described above, except that p-aminobenzoic acid was changed to 4-aminosalicylic acid (manufactured by Tokyo Chemical Industry) at 166 mmol, and dimethylphosphite was changed to diphenylphosphite (manufactured by Tokyo Chemical Industry) at 166 mmol. Compound 1-10 was synthesized. The NMR data of the synthesized compound 1-10 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 10 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-10. ¹ H-NMR (DMSO); 7.1-7.3 (10H), 7.1-7.2 (2H), 7.9 (1H), 11.3 (1H) [Hydroxy group protons confirmed could not]

(Example 11)
Same as compound 1-1 described above except that p-aminobenzoic acid was changed to sulfanilic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol and dimethylphosphite was changed to diethylphosphite (manufactured by Tokyo Chemical Industry Co., Ltd.) to 166 mmol. Compound 1-11 was synthesized. The NMR data of the synthesized compound 1-11 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 11 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-11.
¹ H-NMR (DMSO); 1.2 (6H), 4.8 (4H), 7.7-7.8 (4H) [Proton of sulfonic acid group could not be confirmed]

(Example 12)
Similar to Compound 1-1 described above, except that p-aminobenzoic acid was changed to sulfanilic acid (manufactured by Tokyo Chemical Industry) at 166 mmol and dimethylphosphite was changed to diphenylphosphite (manufactured by Tokyo Chemical Industry) at 166 mmol. Compound 1-12 was synthesized. The NMR data of the synthesized compound 1-12 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 12 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-12.
^{1 1} H-NMR (DMSO); 7.1-7.3 (10H), 7.6-7.7 (4H) [Proton of sulfonic acid group could not be confirmed]

(Example 13)
A sodium salt of [(4-aminobenzoylamino) methane-1,1-diyl] bisphosphonate was synthesized according to the description of US Patent Publication No. 2007/100024. The p-aminobenzoic acid was changed to 166 mmol of [(4-aminobenzoylamino) methane-1,1-diyl] sodium bisphosphonate. Further, dimethyl phosphite was changed to diethyl phosphite (manufactured by Tokyo Chemical Industry Co., Ltd.) at 166 mmol. Except for these matters, compound 1-13 was synthesized in the same manner as in compound 1-1 described above. The NMR data of the synthesized compound 1-13 is shown below. Further, the self-dispersing pigment 13 was obtained in the same manner as in Example 1 above, except that the treatment agent was changed to compound 1-13 and 180 mL of ion-exchanged water was changed to a mixed solution of 120 mL of ion-exchanged water and 60 mL of N-methylpyrrolidone. Water dispersion was obtained.
^{1 1} H-NMR (DMSO); 1.2 (6H), 3.5 (1H), 4.9 (4H), 7.6 (2H), 7.9-8.0 (3H), 11.8 -11.9 (4H, Broad * Protons derived from phosphonic acid groups and attribution)

(Example 14)
The p-aminobenzoic acid was changed to 166 mmol of [(4-aminobenzoylamino) methane-1,1-diyl] sodium bisphosphonate. Further, dimethylphosphite was changed to 166 mmol of diphenylphosphite (manufactured by Tokyo Chemical Industry Co., Ltd.). Except for these matters, compound 1-14 was synthesized in the same manner as in compound 1-1 described above. The NMR data of the synthesized compound 1-14 is shown below. Further, an aqueous dispersion of the self-dispersing pigment 14 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to Compound 1-14.
^{1 1} H-NMR (DMSO); 4.0 (1H), 7.0-7.2 (10H), 7.5 (2H), 7.7-7.9 (3H), 11.8-11. 9 (4H, broad * Proton and attribution derived from phosphonic acid group)

(Example 15)
An aqueous dispersion of the self-dispersing pigment 15 was obtained in the same manner as in Example 1 described above, except that 0.5 mmol / g of potassium ferrocyanide was used as the oxidizing agent.

(Example 16)
An aqueous dispersion of the self-dispersing pigment 16 was obtained in the same manner as in Example 1 above, except that 0.5 mmol / g of phthalocyanine iron (III) chloride (manufactured by Sigma-Aldrich) was used as the oxidizing agent.

(Example 17)
As described above, except that 0.5 mmol / g hydrogen peroxide (used as a 5% hydrogen peroxide aqueous solution (manufactured by Tokyo Chemical Industry Co., Ltd.)) was used as the oxidizing agent and the pH was not adjusted during the reaction. An aqueous dispersion of the self-dispersing pigment 17 was obtained in the same manner as in Example 1. Although the pH was not adjusted, the pH during the reaction was 3.5 because hydrogen peroxide was used.

(Example 18)
As described above, except that 0.5 mmol / g iron (III) chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the oxidizing agent and the pH during the reaction was adjusted to 3.5 using 35% hydrochloric acid. An aqueous dispersion of the self-dispersing pigment 18 was obtained in the same manner as in Example 1.

(Example 19)
Self as in Example 1 above, except that potassium permanganate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the oxidizing agent and the pH during the reaction was adjusted to 3.5 using concentrated sulfuric acid. An aqueous dispersion of the dispersion pigment 19 was obtained.

(Example 20)
An aqueous dispersion of the self-dispersing pigment 20 was obtained in the same manner as in Example 1 except that the stirring time was changed from 48 hours to 120 hours.

(Example 21)
An aqueous dispersion of the self-dispersing pigment 21 was obtained in the same manner as in Example 1 described above, except that the pigment was changed to carbon black (trade name "NIPEX170IQ", manufactured by Orion Engineered Carbons).

(Example 22)
An aqueous dispersion of the self-dispersing pigment 22 was obtained in the same manner as in Example 1 described above, except that the pigment was changed to carbon black (trade name “# 2600”, manufactured by Mitsubishi Chemical Corporation).

(Example 23)
An aqueous dispersion of the self-dispersing pigment 23 was obtained in the same manner as in Example 1 described above, except that the pigment was changed to carbon black (trade name “MCF88”, manufactured by Mitsubishi Chemical Corporation).

(Example 24)
An aqueous dispersion of the self-dispersing pigment 24 was obtained in the same manner as in Example 1 above, except that the pigment was changed to carbon black (trade name "Color Black FW200", manufactured by Orion Engineered Carbons).

(Example 25)
Pigment C.I. I. Pigment Blue 15: 3 (trade name "Heliogen Blue D7079", manufactured by BASF), except that the aqueous dispersion of the self-dispersing pigment 25 was prepared in the same manner as in Example 1 described above. Obtained.

(Example 26)
Pigment C.I. I. An aqueous dispersion of the self-dispersing pigment 26 was obtained in the same manner as in Example 1 above, except that the pigment was changed to Pigment Yellow 155 (trade name “Inkjet Yellow 4G”, manufactured by Clariant).

(Example 27)
Pigment C.I. I. An aqueous dispersion of the self-dispersing pigment 27 was obtained in the same manner as in Example 1 above, except that the pigment red 122 was changed to the trade name "Hostaperm Pink E02" (manufactured by Clariant).

(Example 28)
An aqueous dispersion of the self-dispersing pigment 28 was obtained in the same manner as in Example 1 described above, except that the pH at the time of the reaction was adjusted to 2 with 1 mol / L hydrochloric acid.

(Example 29)
An aqueous dispersion of the self-dispersing pigment 29 was obtained in the same manner as in Example 1 described above, except that the pH during the reaction was adjusted to 9 using 8 mol / L potassium hydroxide.

(Example 30)
Water dispersion of the self-dispersing pigment 30 in the same manner as in Example 1 above, except that the pH during the reaction was adjusted to 2 using 1 mol / L hydrochloric acid and the stirring time was changed from 48 hours to 120 hours. Obtained liquid.

(Example 31)
The self-dispersing pigment 31 was prepared in the same manner as in Example 1 above, except that the pH during the reaction was adjusted to 9 using 8 mol / L potassium hydroxide and the stirring time was changed from 48 hours to 120 hours. An aqueous dispersion was obtained.

(Example 32)
An aqueous dispersion of the self-dispersing pigment 32 was obtained in the same manner as in Example 1 described above, except that the temperature was changed from 60 ° C. to 25 ° C. and the stirring time was changed to 240 hours. This example causes the reaction under mild conditions.

(Example 33)
An intermediate compound was synthesized in the same manner as in Example 1 except that p-aminobenzoic acid was changed to 4-aminophthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) at 166 mmol. Compound 2-1 was synthesized by using the intermediate compound as a raw material and oxidizing it according to the description of Journal of Organic Chemistry, 55 (10), 3023-3028 (1990). The NMR data and MS (mass spectrometry) data of the synthesized compound 2-1 are shown below. Further, an aqueous dispersion of the self-dispersing pigment 33 was obtained in the same manner as in Example 1 described above, except that the treatment agent was changed to compound 2-1.
^{1 1} H-NMR (DMSO); 3.5 (6H), 8.4 (1H), 8.6 (1H), 8.7 (1H), 10.9 (1H), 11.3 (1H)
MS (m / z); 318

(Example 34)
Compound 2-2 was synthesized by using compound 1-1 as a raw material and oxidizing it according to the description of Journal of Organic Chemistry, 55 (10), 3023-3028 (1990). The NMR data and MS (mass spectrometry) data of the synthesized compound 2-2 are shown below. Further, an aqueous dispersion of the self-dispersing pigment 34 was obtained in the same manner as in Example 1 described above, except that the treating agent was changed to Compound 2-2.
^{1 1} H-NMR (DMSO); 3.6 (6H), 8.1 (2H), 8.4 (2H), 11.3 (1H)
MS (m / z); 274

(Example 35)
An intermediate compound was synthesized in the same manner as in Example 1 except that p-aminobenzoic acid was changed to sulfanilic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) at 166 mmol. Using the intermediate compound as a raw material, compound 2-3 was synthesized by oxidizing according to the description of Journal of Organic Chemistry, 55 (10), 3023-3028 (1990). The NMR data and MS (mass spectrometry) data of the synthesized compound 2-3 are shown below. Further, an aqueous dispersion of the self-dispersing pigment 35 was obtained in the same manner as in Example 1 described above, except that the treating agent was changed to Compound 2-3.
¹ H-NMR (DMSO); 3.7 (6H), 8.1 (2H), 8.2 (2H) [Proton of sulfonic acid group could not be confirmed]
MS (m / z); 310

(Comparative Example 1)
According to the description of Patent Document 1, an aqueous dispersion of the comparative self-dispersing pigment 1 was obtained by the procedure shown below. 3.0 mmol / g of p-aminobenzoic acid and 25 mL of ion-exchanged water were placed in a 300 mL flask and kept at a temperature of 5 ° C. in an ice bath. Further, after adding 5 mL of concentrated hydrochloric acid, a liquid in which 1.5 g of sodium nitrite was dissolved was added dropwise to 5.4 mL of ion-exchanged water, and the mixture was stirred for 2 hours while maintaining the temperature to obtain a liquid. After adding 18.0 g of pigment and 200 mL of ion-exchanged water to a vessel (manufactured by Imex) having a capacity of 400 mL, the liquid obtained above was added, and the mixture was stirred at a temperature of 25 ° C. and a rotation speed of 2,000 rpm for 12 hours. As the pigment, carbon black (trade name "Toka Black # 8300", manufactured by Tokai Carbon) was used. Then, 15 mL of a 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the liquid to 9. Then, purification was carried out in the same manner as in Example 1 to obtain an aqueous dispersion of the comparative self-dispersing pigment 1 having a content of the comparative self-dispersing pigment 1 of 10.0%.

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

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

(Comparative Example 4)
According to the description of Patent Document 2, an aqueous dispersion of the comparative self-dispersing pigment 4 was obtained by the procedure shown below. 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 Co., Ltd.) were mixed, and the pH of the liquid was adjusted to 9 using ammonium hydroxide to obtain a mixed solution. It was. As the pigment, carbon black (trade name "Toka Black # 8300", manufactured by Tokai Carbon) was used. The obtained mixed solution was placed in a Pyrex (registered trademark) dish and placed in an oven, and heated at a temperature of 120 ° C. for 24 hours to dry the pigment. The dried pigment was dispersed in ion-exchanged water and subjected to ultrasonic treatment. Then, purification was carried out in the same manner as in Example 1 to obtain an aqueous dispersion of the comparative self-dispersing pigment 4 having a content of the comparative self-dispersing pigment 4 of 10.0%.

(Comparative Example 5)
According to the description of Patent Document 3, an aqueous dispersion of the comparative self-dispersing pigment 5 was obtained by the procedure shown below. Pigment 18.0 g, ion-exchanged water 200 mL, and 2,2-azobis [N- (2-carboxyethyl) -2-methylpropionamide] anhydride (trade name "VA-057", manufactured by Wako Pure Chemical Industries, Ltd.) 1. 0 mmol / g was mixed and stirred at a temperature of 80 ° C. for 12 hours to obtain a reaction solution. As the pigment, carbon black (trade name "Toka Black # 8300", manufactured by Tokai Carbon) was used. After adjusting the temperature of the reaction solution to 25 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the reaction solution to 9. Then, purification was carried out in the same manner as in Example 1 to obtain an aqueous dispersion of the comparative self-dispersing pigment 5 having a content of the comparative self-dispersing pigment 5 of 10.0%.

(Comparative Example 6)
According to the description of Patent Document 4, an aqueous dispersion of the comparative self-dispersing pigment 6 was obtained by the procedure shown below. 18.0 g of pigment and 90 mL of ion-exchanged water were refluxed for 12 hours while heating to a temperature of 60 ° C. in a nitrogen atmosphere. As the pigment, C.I. I. Pigment Red 122 (trade name "Hostaperm Pink E02", manufactured by Clariant) was used. During the reflux, an aqueous solution (0.8 mmol / g) of compound 1-1 (azo compound having a hydrophilic group) described in Patent Document 4 was added dropwise in several steps of 0.01 mol each. Then, the mixture was refluxed for another 24 hours. Then, purification was carried out in the same manner as in Example 1 to obtain an aqueous dispersion of the comparative self-dispersing pigment 6 having a content of the comparative self-dispersing pigment 6 of 10.0%.

<Manufacturing conditions for self-dispersing pigments>
The production conditions of the self-dispersing pigment are shown in Tables 3-1 and 3-2. The meanings of the abbreviations (types of pigments) in Tables 3-1 and 3-2 are as shown below. Further, in Table 3-2, the treatment agent used in Comparative Example 3 was described as "phosphonic acid compound", the treatment agent used in Comparative Example 5 was described as "azo compound 1", and was used in Comparative Example 6. The treatment agent was described as "azo compound 2".
・ CB1: Talker Black # 8300 (made by Tokai Carbon)
・ CB2: NIPEX170IQ (manufactured by Orion Engineered Carbons)
・ CB3: # 2600 (manufactured by Mitsubishi Chemical Corporation)
・ CB4: MCF88 (manufactured by Mitsubishi Chemical Corporation)
・ CB5: Color Black FW200 (manufactured by Orion Engineered Carbons)
-PC: Heliogen Blue D 7079 (manufactured by BASF)
・ AZ: Inkjet Yellow 4G (manufactured by Clariant)
・ QA: Hostaparm Pink E02 (manufactured by Clariant)

<Evaluation>
The following evaluations were performed for each of the production methods of Examples and Comparative Examples. The evaluation results are shown in Tables 4-1 and 4-2. Tables 4-1 and 4-2 also show the structure of the functional groups bonded to the particle surface of the self-dispersing pigment. “Ph” in Tables 4-1 and 4-2 means a phenylene group or a phenyl group.

(Evaluation of reaction efficiency)
After adding 80.0 g of 0.1 mol / L hydrochloric acid to 20.0 g of the aqueous dispersion of the self-dispersing pigment to precipitate the self-dispersing pigment, centrifuge at a rotation speed of 5,000 rpm for 30 minutes to obtain the supernatant liquid. 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 dry product. The obtained dry matter was ground in an agate mortar, and 0.5 g of the solid matter was weighed. After adding 30.0 g of a 0.1 mol / L sodium hydroxide aqueous solution to this solid and stirring for 1 day, centrifugation was performed for 60 minutes at a rotation speed of 80,000 rpm using a centrifuge (manufactured by Beckman Coulter). , The supernatant liquid was collected. The collected liquid was back-titrated to determine the amount of hydrophilic groups contained in the functional groups on the surface of the pigment particles (“the number of moles of hydrophilic groups in the pigment”, which is a value per 1.0 g of the pigment). A potentiometric titrator (trade name "AT-510", manufactured by Kyoto Denshi Kogyo Co., Ltd.) was used for the back titration, 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.

The "number of moles of hydrophilic groups of the treatment agent" was calculated from the number of moles of the treatment agent used per 1.0 g of the pigment when producing the self-dispersing pigment. The "number of moles of hydrophilic groups of the treatment agent" is the number of moles of hydrophilic groups 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 treatment agent, it is calculated as twice the number of moles obtained by using the molecular weight of the treatment agent.

From the "number of moles of hydrophilic groups of the pigment" and "number of moles of hydrophilic groups of the treatment agent" obtained above, the reaction efficiency (%) was calculated based on the following formula (A). For convenience, the reaction efficiency values are shown as integer values rounded to the first decimal place.
Reaction efficiency (%)
= ("Number of moles of hydrophilic groups of pigment" / "Number of moles of hydrophilic groups of treatment agent") x 100
... (A)

From the calculated reaction efficiency values, the reaction efficiency was evaluated according to the evaluation criteria shown below. In the present invention, "C" is an unacceptable level, and "AA", "A" and "B" are acceptable levels in the evaluation criteria shown below.
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%.

(Particle size)
The average particle size of the self-dispersing pigment in the aqueous dispersion (50% cumulative value of the volume-based particle size distribution [D ₅₀ (nm)]) was measured under the following conditions.
-Device: Particle size analyzer using dynamic light scattering method (trade name "Nanotrack UPA150EX", manufactured by Nikkiso Co., Ltd.)
-SetZero: 180 seconds-Number of measurements: 3 times-Measurement time: 120 seconds-Refractive index: 1.8 (carbon black), 1.5 (other pigments)

(Zeta potential)
The hydrophilic groups of self-dispersing pigments have an electric charge, and at least a part of them is ion dissociated in an aqueous liquid. Therefore, when the electrode is inserted into an aqueous liquid containing the self-dispersing pigment and a DC voltage is applied, the self-dispersing pigment moves toward the electrode opposite to the charge of the hydrophilic group of the self-dispersing pigment. Since the zeta potential is proportional to the migration speed at this time, the zeta potential can be obtained from the migration distance per unit time. The variation in the amount of charge contained in the hydrophilic groups of the individual self-dispersing pigments correlates with the half-value width of the zeta potential calculated from the peak shape of the zeta potential spectrum chart. Therefore, the half width of the zeta potential can be used as an index of the variation in the amount of introduced hydrophilic groups, that is, functional groups of the individual self-dispersing pigments. The smaller the half-value width of the zeta potential, the more uniform the amount of functional groups introduced in the self-dispersing pigment, so that the electric double layer that causes the dispersibility of the self-dispersing pigment is uniformly formed for each pigment particle. Therefore, the dispersed state of the self-dispersing pigment tends to be stable.

Water and a 0.1 mol / L sodium hydroxide aqueous solution were added to the aqueous dispersion of the self-dispersing pigment, and the content of the self-dispersing pigment was 5.0 × 10 ^-3 %, and the pH was 8.5-9. A liquid adjusted within the range of 5 was prepared. Using the prepared liquid as a sample, the half width of the zeta potential was calculated from the peak shape of the zeta potential spectrum chart under the following conditions.
-Device: Zeta potential measuring device by electrophoresis light scattering method (trade name "Zetasizer Nano Z", manufactured by Malvern Instruments)
-Sample: Prepared above-Cell: Clear disposable zeta cell
・ Temperature: 25 ℃

(Storage stability)
Each of the following components (unit:%) was mixed, sufficiently stirred, and then pressure-filtered with a membrane filter (trade name "HDCII filter", manufactured by Pall) having a pore size of 1.2 μm to prepare each ink. In addition, "acetylenol E100" is a trade name of a nonionic surfactant (manufactured by Kawaken Fine Chemicals).
-Aqueous dispersion of self-dispersing pigment: 30.0%
・ Glycerin: 10.0%
-Triethylene glycol: 5.0%
・ Acetyrenol E100: 0.2%
-Ion-exchanged water: 54.8%

For the obtained ink, the average particle size of the self-dispersing pigment was measured under the same conditions as the above "particle size" (referred to as "average particle size before the test"). Then, 5.0 g of ink was placed in a petri dish having a diameter of 50 mm and a depth of 17 mm, and placed in a constant temperature bath at a temperature of 40 ° C. for 24 hours to evaporate the liquid component. Then, the same amount of water as the liquid component reduced by evaporation was added, and the self-dispersing pigment was dispersed again by stirring with a stirrer to obtain a liquid. For the obtained liquid, the average particle size of the self-dispersing pigment was measured in the same manner (referred to as "average particle size after the test"). The rate of change in average particle size was calculated from the measured values before and after the test, and the storage stability of the ink 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 in the evaluation criteria shown below.
AA: The rate of change in the average particle size was 20% or less.
A: The rate of change in the average particle size exceeded 20% and was 35% or less.
B: The rate of change in the average particle size exceeded 35% and was 50% or less.
C: The rate of change in the average particle size exceeded 50%.

(Evaluation of image)
Each component (unit:%) shown below is mixed using an aqueous dispersion of self-dispersing pigment, and after sufficient stirring, a membrane filter with a pore size of 1.2 μm (trade name “HDCII filter”, manufactured by Paul) is used. 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%
・ Acetyrenol E100: 0.2%
-Ion-exchanged water: 49.8%

Each of the prepared inks was filled in an ink cartridge, and the ink was mounted on an inkjet recording device (trade name "PIXUS MP480", manufactured by Canon) that ejects ink from a recording head by the action of thermal energy. In this inkjet recording apparatus, a condition is recorded in which one drop of ink having a resolution of 600 dpi × 600 dpi and a mass of 25 ng ± 10% per drop is applied to a unit area of 1/600 inch × 1/600 inch. The duty is defined as 100%. Using this inkjet recording device, a solid image having a recording duty of 100% was recorded on a recording medium (plain paper, trade name "PB PAPER GF-500", manufactured by Canon). Using a spectrophotometer, measure the optical density of the solid image in the recorded material obtained under the conditions of light source: D50 and field of view: 2 °, visually observe the solid image, and image according to the evaluation criteria shown below. Was evaluated. As the spectrophotometer, the trade name "Spectrolino" (manufactured by Gretag Macbeth) was used. When the pigment type was an organic pigment, the evaluation was performed based on the numerical value of the optical density in parentheses. In the present invention, "C" is an unacceptable level, and "A" and "B" are acceptable levels in the evaluation criteria shown below.
A: The optical density was 1.40 (1.10) or more, and the solid image was even and tight.
B: The optical density was 1.40 (1.10) or more, but the solid image had slight unevenness.
C: The optical density was less than 1.40 (1.10).

Claims (12)

A method of producing self-dispersing pigments
At least one processing agent selected from the group consisting of compounds represented by the following general formula (1) represented by compounds Mono及beauty following general formula (2) is reacted to the particle surface of the pigment, hydrophilic A method for producing a self-dispersing pigment, which comprises a step of bonding a functional group containing a sex group to the particle surface of the pigment.

(In the general formula (1), R ₁ and R ₂ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₃ is an aliphatic group, an aromatic group, or a carboxylic acid group, a sulfonic acid, or a group in which an aliphatic group and an aromatic group are directly bonded or bonded via a linker structure. Represents a group substituted with at least one hydrophilic group selected from the group consisting of a group, a phosphate group, and a phosphonic acid group)

(In the general formula (2), R ₄ and R ₅ independently represent an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or an OM, and M is an independent hydrogen atom and an alkali metal, respectively. , Ammonium, or organic ammonium. R ₆ is an aliphatic group, an aromatic group, or a carboxylic acid group, a sulfonic acid, or a group in which an aliphatic group and an aromatic group are directly bonded or bonded via a linker structure. Represents a group substituted with at least one hydrophilic group selected from the group consisting of a group, a phosphate group, and a phosphonic acid group) _{The method for producing an autocovariant pigment according to claim 1, wherein R 3} in the general formula (1) _{and R 6} in the general formula (2) have a structure containing an arylene group and a plurality of carboxylic acid groups. _{R 3} in the general formula (1) _{and R 6} in the general formula (2) are groups in which an aliphatic group and an aromatic group are bonded via a linker structure.
The first or second claim, wherein the linker structure is -O-, -NH-, -CO-, -COO-, -CONH-, -N = N-, -SO-, or -SO _2-. A method for producing a self-dispersing pigment. _{The self-dispersing pigment according to claim 3} , wherein R 3 in the general formula (1) _{and R 6} in the general formula (2) have a structure containing an amide bond (-CONH-) and a phosphonic acid group. Production method. The method for producing an autocovariant pigment according to any one of claims 1 to 4, wherein the step is performed under a condition of pH 1 or more and 13 or less. The method for producing an autocovariant pigment according to any one of claims 1 to 5, wherein the step is carried out in the presence of an oxidizing agent. The method for producing an autocovariant pigment according to any one of claims 1 to 6, wherein the step is carried out in a liquid medium. The method for producing an autocovariant pigment according to any one of claims 1 to 6, wherein the step is carried out in an aqueous system. The method for producing a self-dispersing pigment according to any one of claims 1 to 8, wherein the pigment type constituting the self-dispersing pigment is at least one of an inorganic pigment and an organic pigment. The method for producing a self-dispersing pigment according to any one of claims 1 to 8, wherein the pigment type constituting the self-dispersing pigment is carbon black. A method for producing an ink containing a self-dispersing pigment.
A method for producing an ink, which comprises using a self-dispersing pigment produced by the production method according to any one of claims 1 to 10 as the self-dispersing pigment. An inkjet recording method in which ink is ejected from an inkjet recording head and an image is recorded on a recording medium.
An inkjet recording method, characterized in that the ink produced by the production method according to claim 11 is used as the ink.

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