JP2017061660A - Aqueous pigment dispersion, process for producing the same, coloring composition, ink composition, and ink-jet recording method - Google Patents

Abstract

An aqueous pigment dispersion excellent in storage stability, a method for producing the same, and a coloring composition, an ink composition and an ink jet recording method using the same are provided. In step A, an azo pigment represented by formula (1), a first dispersant and water are mixed to prepare a mixture. In step B, the mixture is dispersed with a disperser, and an aqueous pigment is prepared. A method for producing an aqueous pigment dispersion comprising, in this order, a step of obtaining a dispersion A and a step of adding a second dispersant to the aqueous pigment dispersion A to obtain an aqueous pigment dispersion as Step C. [Selection figure] None

Description

  The present invention relates to an aqueous pigment dispersion and a production method thereof, a coloring composition, an ink composition, and an inkjet recording method.

  In recent years, a material for forming a color image has been mainly used as an image recording material, and specifically, an ink jet recording material, a thermal transfer recording material, an electrophotographic recording material, a transfer halogen. Silver halide photosensitive materials, printing inks, recording pens, and the like are actively used. Further, a color filter is used for recording and reproducing a color image in an imaging device such as a charge coupled device (CCD) in a photographing apparatus and in a liquid crystal display (LCD) or a plasma display (PDP) in a display. In these color image recording materials and color filters, so-called additive color mixing and subtractive color mixing three primary colors (dyes and pigments) are used to display or record full color images.

Azo pigments are widely used in printing inks, ink compositions for ink jet recording, electrophotographic materials, and the like because they are excellent in hue and coloring power, which are color characteristics.
In various colored compositions, when a pigment is used as a colorant, it is important to ensure the dispersibility and dispersion stability of the solid pigment.
From the viewpoints of pollution prevention and occupational health, water-based industries are strongly oriented in industries that use colorants such as paints and printing inks. Further, stationery such as ballpoint pens and sign pens used for recording information, and recording liquids such as printers and plotters typified by ink jets are becoming water-based in terms of toxicity and hygiene.
Furthermore, in recent years, an aqueous dispersion in which a water-insoluble solid such as a pigment is dispersed has been widely used as an ink composition for ink jet recording.
As conventional pigment dispersions, those described in Patent Documents 1 and 2 are known.

JP 2011-74376 A JP 2011-46870 A

  The problem to be solved by the present invention is to provide an aqueous pigment dispersion excellent in storage stability and a method for producing the same, and a coloring composition, an ink composition, and an inkjet recording method using the aqueous pigment dispersion. is there.

  The above-described problems of the present invention have been solved by the following means.

[1]
Step A is represented by the following formula (1) having a characteristic X-ray diffraction peak at least at a Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction of 7.6 ° and 25.6 °. Mixing at least one of an azo pigment and its tautomer, a first dispersant, and water to produce a mixture;
As step B, the above mixture is dispersed with a disperser to obtain an aqueous pigment dispersion A, and
A method for producing an aqueous pigment dispersion, comprising, as Step C, a step of adding a second dispersant to the aqueous pigment dispersion A obtained in Step B to obtain an aqueous pigment dispersion in this order .

[2]
The method for producing an aqueous pigment dispersion according to [1], wherein at least one of the first dispersant and the second dispersant is a polymer dispersant.
[3]
The method for producing an aqueous pigment dispersion according to [1] or [2], wherein the first dispersant and the second dispersant satisfy any of the following (i) to (iii).
(I) the first dispersant is a long chain fatty acid salt, the total acid value and amine value of the second dispersant is 30 mg KOH / g or more, the amine value is 5 mg KOH / g or more, and the amine (Ii) The sum of the acid value and amine value of the first dispersant is less than 30 mg KOH / g, the amine value is 5 mg KOH / g or more, the amine value is greater than the acid value, and The sum of the acid value and amine value of the second dispersant is 30 mg KOH / g or more, and the acid value is more than the amine value.
(Iii) The sum of the acid value and the amine value of the first dispersant is less than 30 mgKOH / g, the acid value is 5 mgKOH / g or more, the acid value is more than the amine value, and the second dispersant The sum of the acid value and the amine value is 30 mgKOH / g or more, the amine value is 5 mgKOH / g or more, and the amine value is larger than the acid value [4]
Furthermore, the manufacturing method of the aqueous pigment dispersion liquid of any one of [1]-[3] including the process of making the electrical conductivity of an aqueous pigment dispersion liquid into 100 microsiemens / cm or less.
[5]
The total content of the first dispersant and the second dispersant is 10 to 90% by mass with respect to at least one of the azo pigment represented by the formula (1) and tautomers thereof, [ The method for producing an aqueous pigment dispersion according to any one of [1] to [4].
[6]
The aqueous pigment dispersion according to any one of [1] to [5], wherein at least one of the azo pigment represented by the formula (1) and a tautomer thereof is not salt milled. Liquid manufacturing method.
[7]
An aqueous pigment dispersion produced by the method for producing an aqueous pigment dispersion according to any one of [1] to [6].
[8]
A coloring composition containing the aqueous pigment dispersion according to [7].
[9]
An ink composition containing the aqueous pigment dispersion according to [7] or the coloring composition according to [8].
[10]
The ink composition according to [9], which is an ink composition for inkjet recording.
[11]
[10] An ink jet recording method comprising a step of ejecting the ink composition for ink jet recording according to [10] onto a recording medium by an ink jet method.

  ADVANTAGE OF THE INVENTION According to this invention, the aqueous pigment dispersion excellent in storage stability, its manufacturing method, and the coloring composition, ink composition, and inkjet recording method using the said aqueous pigment dispersion can be provided.

2 is an X-ray diffraction pattern of an azo pigment (1) synthesized in Synthesis Example 1. FIG.

Hereinafter, the present invention will be described in detail.
In addition, in this specification, description of "xx-yy" represents the numerical range containing xx and yy. Further, “a polymer having a basic functional group at at least one of the ends of the main chain” or the like is also simply referred to as “component A” or the like.
In the present invention, “mass%” and “wt%” are synonymous, and “part by mass” and “part by weight” are synonymous.
In the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present specification, regarding the notation of the group in the compound represented by the formula, when not substituted or unsubstituted, and when the above group can further have a substituent, unless otherwise specified, In addition to an unsubstituted group, a group having a substituent is also included. For example, in the description of the formula, if “R represents an alkyl group, a cycloalkyl group, or an aryl group” is described, “R represents an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted cycloalkyl group, a substituted cycloalkyl”. Represents a group, an unsubstituted aryl group or a substituted aryl group. In the present specification, (meth) acryl represents a concept including both acryl and methacryl, and the same applies to (meth) acrylate, (meth) acrylic acid, and the like.
Moreover, the polymer in this specification shall include a copolymer.

(Method for producing aqueous pigment dispersion and aqueous pigment dispersion)
In the process for producing the aqueous pigment dispersion of the present invention (hereinafter also simply referred to as “pigment dispersion”), as step A, at least the Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction is 7.6. At least one selected from the azo pigment represented by the formula (1) having a characteristic X-ray diffraction peak at 2 ° and 25.6 °, and a tautomer thereof, a first dispersant and water are mixed. Then, as the step of preparing the mixture, Step B, the above mixture is dispersed with a disperser to obtain an aqueous pigment dispersion A, and as Step C, the aqueous pigment dispersion A obtained in Step B is added to the second step. And a step of adding an aqueous dispersant to obtain an aqueous pigment dispersion in this order.
The aqueous pigment dispersion of the present invention is an aqueous pigment dispersion produced by the method for producing an aqueous pigment dispersion of the present invention.

  In the method for producing an aqueous pigment dispersion of the present invention, a pigment dispersion having a desired particle diameter can be obtained in a short time by using a specific compound as the first dispersant and the second dispersant. Furthermore, an aqueous pigment dispersion having excellent storage stability and excellent image fastness when used in an ink composition can be easily obtained. In the case of a dispersant that has a weak adsorptivity with pigment particles, it often exhibits easy dispersibility, but due to its weak adsorptivity to pigment particles, it tends to be desorbed from the pigment particles and often has poor storage stability. . On the other hand, a dispersant having excellent storage stability often has poor dispersibility because it is difficult to desorb from the pigment particles. In the present invention, it is presumed that each effect was effectively obtained by using a specific dispersant in combination.

<Process A>
In the method for producing an aqueous pigment dispersion of the present invention, as step A, at least CuKα characteristic X-ray diffraction has a Bragg angle (2θ ± 0.2 °) of 7.6 ° and 25.6 ° characteristic X-ray diffraction. It includes a step of mixing at least one selected from the azo pigment represented by formula (1) having a peak and a tautomer thereof, a first dispersant, and water to prepare a mixture.
An azo pigment represented by formula (1) having a characteristic X-ray diffraction peak at Bragg angles (2θ ± 0.2 °) of 7.6 ° and 25.6 ° at least in CuKα characteristic X-ray diffraction in step A Details of at least one selected from the tautomers thereof and the first dispersant will be described later.
The total content of the azo pigment represented by formula (1) in the above mixture (hereinafter also referred to as “specific pigment” or “azo pigment represented by formula (1)”) and its tautomer is the mixture The total mass is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, still more preferably 1 to 20% by mass, and 5 to 15% by mass. It is particularly preferred that
The total content of the first dispersant in the mixture is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, based on the total mass of the mixture, It is more preferable that it is 20 mass%, and it is especially preferable that it is 5-15 mass%.

The mixing method in step A is not particularly limited, and a known mixing method and a known mixing apparatus can be used, but mixing by stirring and mixing is preferable.
Moreover, the mixing temperature and mixing time in the step A are not particularly limited, and may be appropriately selected according to the desired progress of mixing.
In step A, the mixing of the azo pigment represented by the formula (1), the first dispersant, and water is not particularly limited and may be mixed in any order to prepare a mixture. The first dispersant and water are preferably mixed to obtain a mixture.
Further, the mixing and dispersing time in the step A is not particularly limited, and may be appropriately selected according to a desired dispersion state.
Moreover, in the process A, you may add other components, such as the antiseptic | preservative mentioned later and a polyvalent metal ion, as needed.

<Process B>
The method for producing an aqueous pigment dispersion of the present invention includes, as Step B, a step of dispersing the above mixture with a disperser to obtain an aqueous pigment dispersion.

The dispersion method in step B can be performed using a known method or a dispersion apparatus, and is not particularly limited.
In step B, it is preferable to disperse so that the volume average particle diameter of the azo pigment represented by formula (1) falls within a desired range, and the volume average particle diameter of the azo pigment represented by formula (1) is It is more preferable to disperse so as to be 100 nm or less.

The method for dispersing the mixture in Step B can be performed using a known method or a dispersing device, and is not particularly limited. Step B includes, for example, a mill method (for example, a colloid mill, a ball mill, a sand mill, a bead mill, an attritor, a roll mill, a jet mill, a paint shaker, an agitator mill, etc.), an ultrasonic method (ultrasonic homogenizer), and a high-pressure emulsification dispersion method. (High-pressure homogenizer; specific commercially available devices such as gorin homogenizers, microfluidizers, DeBEE2000, etc.), high-speed stirring type dispersers, and the like can be used.
Among these, a mill system is preferable, a medium dispersion system (colloid mill, ball mill, sand mill, bead mill, etc.) is more preferable, and a bead mill is still more preferable.

<Process C>
The method for producing an aqueous pigment dispersion of the present invention includes, as Step C, a step of adding a second dispersant to the aqueous pigment dispersion A obtained in Step B to obtain an aqueous pigment dispersion.
The total content of the second dispersant in the aqueous pigment dispersion is preferably 0.1 to 20% by mass, more preferably 0.2 to 17% by mass with respect to the total mass of the mixture. 0.3 to 15% by mass is more preferable, and 0.5 to 10% by mass is particularly preferable.
Further, the total content of the first dispersant and the second dispersant with respect to at least one selected from the azo pigment represented by the formula (1) and tautomers thereof is 10 to 80% by mass. It is preferable that it is 20-80 mass%, and it is still more preferable that it is 30-70 mass%.

<Step of setting the electric conductivity of the aqueous pigment dispersion to 100 μS / cm or less>
The method for producing an aqueous pigment dispersion of the present invention preferably further includes a step of setting the electric conductivity of the aqueous pigment dispersion to 100 μS / cm or less after Step C.
The electric conductivity of the aqueous pigment dispersion can be set to 100 μS / cm or less from the viewpoint of imparting ink storage stability and ink ejection properties. The electric conductivity of the aqueous pigment dispersion is preferably 1 to 100 μS / cm, more preferably 1 to 50 μS / cm, and even more preferably 1 to 20 μS / cm. By having this step, an effect of storage stability of ink can be obtained.
Amberlite treatment (ion exchange resin treatment), ultrafiltration treatment (ultrafiltrate (UF) treatment), or the like can be used to adjust the electrical conductivity value. The UF processing is also described in JP 2011-144298 A, [0247] to [0249], and can also be referred to in the present invention.

  In the present invention, in addition to the above steps A to C and the step of setting the electric conductivity of the aqueous pigment dispersion to 100 μS / cm or less, other steps may be included.

  The timing for performing each step may be any timing as long as it is after step C.

<Process D>
The method for producing an aqueous pigment dispersion of the present invention preferably further includes, after Step C, Step D as a step D (hereinafter also simply referred to as “heat treatment step”). By having the heat treatment step, the relationship between the pigment and the dispersant in the aqueous pigment dispersion becomes more stable, and an aqueous pigment dispersion excellent in storage stability can be obtained.
The heating temperature in the heat treatment step is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 50 ° C. or higher and 85 ° C. or lower, and still more preferably 60 ° C. or higher and 80 ° C. or lower.
The heating time in the heat treatment step is preferably 5 minutes or longer, more preferably 5 minutes to 24 hours, and further preferably 30 minutes to 12 hours.
In the heat treatment step, the heat treatment may be performed while stirring.

  The method for producing an aqueous pigment dispersion of the present invention may include other steps in addition to the above-described Step A to Step D.

<PH adjustment step>
The method for producing an aqueous pigment dispersion of the present invention may have a pH adjustment step. By adjusting the pH to a specific value, an aqueous pigment dispersion excellent in storage stability can be obtained.
The pH adjustment step may be performed at a desired timing after Step A and Step B, but is preferably performed between Step C and Step D or after Step D, and is performed after Step D. Is more preferable.
Moreover, the manufacturing method of the aqueous pigment dispersion of this invention is performed in order of the process C, the deionization process mentioned later, the pH adjustment process, and the process D, or the process C, the process D, the deionization process mentioned later It is preferable to perform in the order of the pH adjustment step, and it is particularly preferable to perform in the order of the step C, the step D, the deionization step described later, and the pH adjustment step.
The pH adjuster is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting the recording ink to be prepared, and can be appropriately selected according to the purpose. Amines (eg, diethanolamine, triethanolamine, triisopropanolamine, 2-amino-2-ethyl-1,3-propanediol), alkali metal hydroxides (eg, lithium hydroxide, sodium hydroxide, potassium hydroxide) Etc.), ammonium hydroxide (for example, ammonium hydroxide, quaternary ammonium hydroxide), phosphonium hydroxide, alkali metal carbonate and the like.
The pH of the dispersion is preferably 6 to 11 and particularly preferably 7 to 10 from the viewpoint of storage stability.

<Sterilization process>
The sterilization referred to in the present invention means an operation having a sterilizing action, and examples thereof include addition of an additive having a sterilizing effect such as irradiation with light such as ultraviolet rays (UV) and alcohol. Among them. Light irradiation is preferred.
By having a sterilization step, an aqueous pigment dispersion superior in storage stability can be obtained.
As the light irradiation means, those capable of irradiating near-ultraviolet light to ultraviolet light of 400 nm or less are preferable, and specifically, a xenon lamp, a high-pressure mercury lamp, a black light, a sterilizing lamp, or the like is preferably used.
The light irradiation time and the light irradiation amount are not particularly limited and can be appropriately selected.

<Deionization process>
The method for producing an aqueous pigment dispersion of the present invention may have a deionization step. By removing ionic components contained as impurities in the specific pigment or dispersant, an aqueous pigment dispersion having excellent storage stability can be obtained.
The deionization step may be performed at a desired timing, but is preferably performed between step C and step D or after step D, and more preferably after step D.
Examples of the method for removing the ionic component include a method using a membrane separation method such as ultrafiltration and nanofiltration, a method of adding an ion exchange resin, and the like.

<Centrifuge separation process>
The method for producing an aqueous pigment dispersion of the present invention may include a step of centrifuging the aqueous pigment dispersion obtained in Step C or D. Coarse particles can be removed by centrifugation. In addition, the method for producing an aqueous pigment dispersion of the present invention may include a step of centrifuging the aqueous pigment dispersion A and the aqueous pigment dispersion before Step B.
The centrifugal separation step is preferably performed before the filtration step described later. By having the centrifugal separation step before the filtration step, it is possible to suppress the coarse particles from being clogged and reducing the filterability.
As centrifugal force at the time of centrifugal separation, 500G to 50,000G is preferable, 700G to 20,000G is more preferable, and 1,000G to 15,000G is still more preferable. When it is 500 G or more, coarse particles can be sufficiently settled and removed, and when it is 50,000 G or less, sedimentation of the dispersed pigment is suppressed.

<Filtration process>
The method for producing an aqueous pigment dispersion of the present invention may include a step of filtering the aqueous pigment dispersion A obtained in Step B and / or the aqueous pigment dispersion obtained in Steps C and D. .
Coarse particles can be removed by filtration. The filtration step is not particularly limited as long as it is after the pigment is dispersed, but is preferably performed after the addition of the preservative or as the final step of completing the aqueous pigment dispersion.
In particular, in the case of having the heat treatment step, a part of the dispersed pigment and dispersant may be dried or aged to become coarse particles and settle.
The filter that can be used is not particularly limited as long as filtration can be performed, but filter cloth, filter paper, and membrane are preferable. The pore size of the filter is preferably 0.1 mm or less, more preferably 10 μm or less, still more preferably 5 μm or less, and particularly preferably 1 μm or less.

  Hereinafter, at least one selected from the azo pigment represented by the formula (1) and its tautomer, the first dispersant, and the second dispersant used in the present invention will be described in detail. To do.

<Azo pigment represented by formula (1)>
Hereinafter, the azo pigment represented by the formula (1) in the present invention will be described in detail.

In the present invention, the X-ray diffraction measurement of the azo pigment represented by the following formula (1) is performed in accordance with Japanese Industrial Standard JISK0131 (general rules for X-ray diffraction analysis). Manufactured).
The azo pigments represented by the formula (1) having X-ray diffraction peaks characteristic at 7.6 ° and 25.6 ° and / or their tautomers further include 7.6 °, 13.5 °. The azo pigments represented by the formula (1) having X-ray diffraction peaks characteristic at 25.6 ° and 27.7 ° and / or tautomers thereof are more preferable. Among them, in particular, it is represented by the formula (1) having characteristic X-ray diffraction peaks at 7.6 °, 13.5 °, 15.9 °, 16.9 °, 25.6 ° and 27.7 °. Most preferred are azo pigments and / or tautomers thereof.
The azo pigment represented by the formula (1) may be a salt, hydrate or solvate thereof.
In the pigment represented by the formula (1), a hydrate containing water molecules in the crystal, or a solvent (for example, alcohols such as methanol, ethanol, 2-propanol, t-butyl alcohol, acetone, methyl ethyl ketone, etc. Or aprotic solvents such as acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, toluene, etc.).

In addition, with respect to the pigment represented by the formula (1), tautomers such as Scheme 1 (for example, azo-hydrazone tautomers) are also included in these formulas in the present invention. To do. Incidentally, _(t) C 4 _{H 9} represents a t- butyl group.

  Further, a geometric isomer of the pigment represented by the formula (1) may be included as a minor component.

[Synthesis of Azo Pigment Represented by Formula (1)]
The azo pigment represented by the formula (1) can be synthesized by a known method.
The obtained product can be used after being treated according to a post-treatment method of a normal organic synthesis reaction and then purified or not purified.
That is, for example, the product liberated from the reaction system can be used without being purified, or can be used alone or in combination for purification by recrystallization, salt formation or the like.
In addition, after completion of the reaction, it is put into water or ice, and the operation of purifying the product liberated or extracted with an organic solvent / aqueous solution without purification or by recrystallization, crystallization, salt formation or the like alone or It can also be served after combined. Note that the reaction solvent may be distilled off in advance in water or ice, or may be put in water or ice without being distilled off. Furthermore, it may be neutralized after being put in water or ice, or may not be neutralized.

[Post-processing]
The azo pigment represented by the formula (1) may be subjected to post-treatment as necessary. Examples of post-treatment methods include solvent salt milling, salt milling, dry milling, solvent milling, pigment particle control step by grinding treatment such as acid pasting, solvent heating treatment, resin, surfactant and dispersant. The surface treatment process by etc. is mentioned.

The primary particle diameter can be reduced by performing post-treatment such as solvent salt milling or salt milling. Therefore, in order to make the pigment particles into a more preferable form, it is preferable to perform solvent salt milling, salt milling or dry milling from the viewpoint of dispersibility and stability over time.
The method for producing the aqueous pigment dispersion of the present invention preferably does not perform such post-treatment, particularly solvent salt milling or salt milling. In the production method of the aqueous pigment dispersion of the present invention, an aqueous pigment dispersant having sufficiently excellent storage stability can be obtained without performing such post-treatment, so that the cost and the simplicity of the process can be obtained. Excellent.
Moreover, it is preferable that the azo pigment represented by Formula (1) in the aqueous pigment dispersion of the present invention is not subjected to salt milling.

-Solvent salt milling-
As solvent salt milling, for example, a crude azo pigment, an inorganic salt, and an organic solvent that does not dissolve the crude azo pigment are charged into a kneader and kneaded and ground therein. As said inorganic salt, water-soluble inorganic salt can be used conveniently, For example, it is preferable to use inorganic salts, such as sodium chloride, potassium chloride, sodium sulfate. Moreover, it is more preferable to use an inorganic salt having an average particle size of 0.5 to 50 μm.
The amount of the inorganic salt used is preferably 3 to 20 times by mass, more preferably 5 to 15 times by mass with respect to the crude azo pigment. As the organic solvent, a water-soluble organic solvent can be suitably used, and the solvent easily evaporates due to a temperature rise during kneading, so that a high boiling point solvent is preferable from the viewpoint of safety.

Examples of such organic solvents include diethylene glycol, glycerin, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (isopentyloxy) ethanol. , 2- (hexyloxy) ethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene Glycol, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipro Glycol or mixtures thereof.
The amount of the water-soluble organic solvent used is preferably 0.1 to 5 times by mass with respect to the crude azo pigment. The kneading temperature is preferably 20 ° C to 130 ° C, particularly preferably 40 ° C to 110 ° C.
As a kneader, for example, a kneader or a mix muller can be used.

[Average primary particle diameter of azo pigment represented by formula (1)]
When the primary particles of the azo pigment represented by the above formula (1) are observed with a transmission microscope, the length in the major axis direction is preferably 0.01 μm or more and 10 μm or less as an average value. It is more preferably from 01 μm to 3 μm, further preferably from 0.02 μm to 0.5 μm, particularly preferably from 0.02 μm to 0.2 μm, and most preferably from 0.02 μm to 0.15 μm. When it is in the above-mentioned range, high fastness to light and ozone is exhibited, the dispersibility is excellent, and the storage stability of the aqueous pigment dispersion is excellent.

  The total content of the azo pigment represented by formula (1) and the tautomer thereof in the aqueous pigment dispersion of the present invention is 0.1 to 30% by mass with respect to the total mass of the aqueous pigment dispersion. Is more preferable, 0.5 to 25% by mass is more preferable, 1 to 20% by mass is further preferable, and 5 to 15% by mass is particularly preferable.

[Particle size through all methods]
The volume average particle diameter of the azo pigment represented by the formula (1) is preferably 0.01 to 10 μm, more preferably 0.01 to 3 μm, and 0.02 to 0.5 μm. Is more preferable, 0.02 to 0.2 μm is particularly preferable, and 0.02 to 0.15 μm is most preferable.

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

<First dispersant and second dispersant>
The aqueous pigment dispersion of the present invention contains a first dispersant and a second dispersant.
The first dispersant and the second dispersant in the present invention are not particularly limited except that they are different dispersants, but the first dispersant and the second dispersant are the following (i) to (i): It is preferable to satisfy any of (iii), and it is most preferable to satisfy (ii).
(I) the first dispersant is a long chain fatty acid salt, the total acid value and amine value of the second dispersant is 30 mg KOH / g or more, the amine value is 5 mg KOH / g or more, and the amine The value is greater than the acid value.
(Ii) The sum of the acid value and the amine value of the first dispersant is less than 30 mgKOH / g, the amine value is 5 mgKOH / g or more, the amine value is greater than the acid value, and the second dispersant The sum of the acid value and the amine value is 30 mgKOH / g or more, and the acid value is more than the amine value.
(Iii) The sum of the acid value and the amine value of the first dispersant is less than 30 mgKOH / g, the acid value is 5 mgKOH / g or more, the acid value is more than the amine value, and the second dispersant The sum of the acid value and the amine value is 30 mgKOH / g or more, the amine value is 5 mgKOH / g or more, and the amine value is larger than the acid value.

  The acid value in the present invention represents an acid value per 1 g of the solid content of the dispersant, and can be determined by potentiometric titration according to JIS K 0070. The amine value represents an amine value per 1 g of the solid content of the dispersant, and is a value converted to an equivalent of potassium hydroxide after being obtained by potentiometric titration using a 0.1 mol / L hydrochloric acid aqueous solution.

In the embodiment (i), the long chain fatty acid salt used as the first dispersant is preferably an alkali metal salt of a long chain fatty acid having 12 to 36 carbon atoms, specifically, sodium oleate. And potassium oleate, sodium stearate, potassium stearate, sodium palmitate, potassium palmitate and the like. Among these, sodium oleate and sodium stearate are preferably exemplified.
Moreover, as a 2nd dispersing agent in the aspect of said (i), the sum total of an acid value and an amine value is 30 mgKOH / g or more, It is preferable that it is 30-150 mgKOH / g, It is 30-100 mgKOH / g. It is more preferable. The amine value is 5 mgKOH / g or more, preferably 5 to 150 mgKOH / g, and more preferably 10 to 100 mgKOH / g. The difference between the amine value and the acid value (amine value-acid value) is preferably 0 to 200 mgKOH / g, more preferably 0 to 150 mgKOH / g, and further preferably 0 to 100 mgKOH / g. preferable.

As a 1st dispersing agent in the aspect of said (ii), it is preferable that the sum total of an acid value and an amine value is smaller than 30 mgKOH / g, is 5-25 mgKOH / g, and is 10-25 mgKOH / g more. preferable. The difference between the amine value and the acid value (amine value-acid value) is preferably 0.1 to 25 mgKOH / g, and more preferably 1 to 20 mgKOH / g.
As a 2nd dispersing agent in the aspect of said (ii), the sum total of an acid value and an amine value is 30 mgKOH / g or more, It is preferable that it is 30-150 mgKOH / g, It is 30-100 mgKOH / g. More preferred. The difference between the acid value and the amine value (acid value-amine value) is preferably 0 to 200 mgKOH / g, more preferably 0 to 150 mgKOH / g, and 0 to 100 mgKOH / g. Is more preferable.

As a 1st dispersing agent in the aspect of said (iii), it is preferable that the sum of an acid value and an amine value is smaller than 30 mgKOH / g, is 5-25 mgKOH / g, and is more preferably 10-25 mgKOH / g. preferable. Moreover, an acid value is 5 mgKOH / g or more, it is preferable that it is 5-150 mgKOH / g, and it is more preferable that it is 10-100 mgKOH / g or more. The difference between the acid value and the amine value (acid value-amine value) is preferably from 0.1 to 25 mgKOH / g, more preferably from 1 to 20 mgKOH / g.
As a 2nd dispersing agent in the aspect of said (iii), the sum total of an acid value and an amine value is 30 mgKOH / g or more, It is preferable that it is 30-150 mgKOH / g, It is 30-100 mgKOH / g. More preferred. The amine value is 5 mgKOH / g or more, preferably 5 to 150 mgKOH / g, and more preferably 10 to 100 mgKOH / g. The difference between the amine value and the acid value (amine value-acid value) is preferably 0 to 200 mgKOH / g, more preferably 0 to 150 mgKOH / g, and 0 to 100 mgKOH / g. Is more preferable.

Moreover, it is preferable that a 1st dispersing agent and a 2nd dispersing agent satisfy | fill any of following (iv)-(v).
(Iv) The first dispersant is a dispersant selected from group A, and the second dispersant is a dispersant selected from group D.
(V) The first dispersant is a dispersant selected from group B, and the second dispersant is a dispersant selected from group C.
Group A: EFKA 4560, EFKA 4580, EFKA 4585, DISPERBYK-183 and DISPERBYK-184
Group B: DISPERBYK-190, DISPERBYK-2091, EFKA 4520, sodium oleate, sodium stearate Group C: EFKA 4510, EFKA 5071, EFKA 6220, EFKA 4800
Group D: DISPERBYK-181, DISPERBYK-180, DISPERBYK-187, DISPERBYK-194, DISPERBYK-2090, EFKA 6225
Among these, particularly preferable combinations of the first dispersant and the second dispersant (first dispersant, second dispersant) include (EFKA 4585, DISPERBYK-181), (EFKA 4585, DISPERBYK- 187), (DISPERBYK-184, DISPERBYK-187), (EFKA 5071, DISPERBYK-2090), (EFKA 4560, DISPERBYK-187), among these (EFKA 4585, DISPERBYK-181), (EFKA45) , DISPERBYK-187) and (EFKA 4560, DISPERBYK-187) are more preferable, and (EFKA 4585, DISPERBYK-181), (EFKA 4585, DISPERBYK-187) are more preferable. Preferably, the most preferred combination of (EFKA 4585, DISPERBYK-181).
The EFKA (registered trademark) series is a dispersant manufactured by BASF, and the DISPERBYK (registered trademark) series is a dispersant manufactured by BYK Chemie.
The acid value and amine value of these commercial products are shown below.

From the viewpoint of dispersibility and storage stability of the pigment dispersion, it is preferable that both the first dispersant and the second dispersant are water-soluble dispersants.
The first dispersant and the second dispersant have a solubility in water of preferably 1 g / 100 mL or more, more preferably 3 g / 100 mL or more, and 5 g / 100 mL or more. Is more preferable. When the solubility in water is 1 g / 100 mL or more, the solubility in water is excellent, the adsorptivity to a specific pigment is excellent, and good dispersibility is obtained.
Further, from the viewpoint of the image quality of the printed matter, either the first dispersant or the second dispersant is preferably a polymer dispersant, and the first dispersant is at least a polymer dispersant. More preferably.
The polymer dispersant in the present invention is a dispersant having a weight average molecular weight of 1,000 or more.
In the present invention, the weight average molecular weight of the dispersant is preferably 5,000 or more and 200,000 or less, more preferably 8,000 or more and 150,000 or less, and more preferably 10,000 or more and 100,000 or less. Further preferred. When the weight average molecular weight is 5,000 or more, the image quality of the printed matter is excellent. On the other hand, when the weight average molecular weight is 200,000 or less, it is possible to suppress an increase in viscosity and further prevent a decrease in storage stability.

  In the present invention, the weight average molecular weight of the compound is measured by a gel permeation chromatography method using a polystyrene standard or a polyethylene oxide standard. In addition, when there is a catalog value as the weight average molecular weight of the polymer dispersant, the catalog value can also be adopted.

In the present invention, the polymer dispersant preferably includes polyurethane, polyester, and / or polyvinyl resin, more preferably polyurethane, polyester, and / or polyvinyl resin, and is preferably a polyvinyl resin. Further preferred.
The polymer dispersant is preferably a dispersant obtained by polymerizing both a hydrophilic monomer and a hydrophobic monomer.
The polyvinyl resin in the present invention is a homopolymer or copolymer of an ethylenically unsaturated monomer, and examples thereof include acrylic resins and styrene resins.

The hydrophilic monomer is a monomer containing hydrophilicity that is an ionic group or a nonionic group. The ionic group may be a cation or an anion.
Both cationic groups and anionic groups provide amphoteric stabilization to the dispersant.
Preferred anionic groups are carboxyl groups, phenolic hydroxy groups, sulfonic acid groups, sulfuric acid groups, phosphonic acid groups, polyphosphoric acid groups, phosphoric acid groups, and salts thereof.
Preferred cationic groups are a quaternary ammonium group, a benzalkonium group, a guanidinium group, a biguanidinium group, and a pyridinium group. These may be in the form of salts such as hydroxides, sulfates, nitrates, chlorides, bromides, iodides and fluorides.
The nonionic group is preferably a glucooxide structure, a sugar structure, a pyrrolidone structure, an acrylamide group, a hydroxy group or a poly (alkylene oxide) group, and more preferably a poly (ethylene oxide) group or a poly (propylene oxide) group. _{preferably, - (CH 2 CH 2 O} ) n H or - it is more preferably an alkyl _{- (CH 2 CH 2 O)} n C 1-4. Here, n represents 3 to 200 (preferably 4 to 20). Further, hereinafter, for example, the expression of C _1-4- represents “having 1 to 4 carbon atoms”.
The polymer may contain only nonionic groups, a plurality of nonionic groups throughout the polymer, and one or more polymer chains containing nonionic groups. A hydroxy group is inserted using, for example, polyvinyl alcohol, a (meth) acryl compound having a hydroxy group, or cellulose. The ethyleneoxy group is inserted using a polymer chain such as polyethylene oxide.

A hydrophobic monomer is a monomer containing a hydrophobic group. Typical ones having a hydrophobic group are hydrocarbons, fluorocarbons, poly C _3-4 -alkyleneoxys and alkylsiloxanes having a hydrophilic group of 3 or less, preferably 0. Further, the hydrophobic monomer may have propylene oxide in a side chain or a straight chain.
The polymer may be a homopolymer, but is preferably a copolymer. The polymer may be a random polymer (statistically short blocks or segments) or a graft polymer (long blocks or segments). The polymer may also be an alternating polymer. The polymer may be branched but is preferably linear. The polymer may have more than one segment (eg, block and graft, copolymer), but is preferably random.
In embodiments where the polymer has two or more segments, it is preferred that at least one segment is hydrophobic and at least one segment is hydrophilic relative to each other. A preferred method of creating hydrophobic and hydrophilic segments is by copolymerization of hydrophobic and hydrophilic monomers, respectively. If the polymer has at least one hydrophobic segment and at least one hydrophilic segment, the carboxyl group may be in the hydrophobic segment, in the hydrophilic segment, or in both segments.

The vinyl polymer (polyvinyl resin) may be produced by any suitable means. A preferred method for producing a vinyl polymer is free radical polymerization using (meth) acrylate and a vinyl monomer such as vinyl naphthalene or styrene monomer. Suitable free radical polymerization is not limited to suspension polymerization, solution polymerization, dispersion polymerization and emulsion polymerization, but is preferably solution polymerization.
The vinyl polymer is preferably a (meth) acrylate monomer.
The vinyl polymer is preferably a copolymer.
Copolymers derived from hydrophobic and hydrophilic monomers are preferably substantially free of segments. For example, the copolymer is made by free radical polymerization such that the segment length is very short or absent. Such cases are often referred to as “random” polymerization. Copolyvinyl polymers with segments are produced by living polymerization, especially polymerization methods such as group transfer polymerization, atom transfer polymerization, macromonomer polymerization, graft polymerization, anionic or cationic polymerization. The
Suitable hydrophilic vinyl monomers are nonionic and ionic monomers.
Preferred nonionic monomers are saccharides, glucose compounds, amide compounds and pyrrolidone compounds, particularly those having a hydroxy group and an ethoxy group.
Examples of preferred nonionic monomers include hydroxyethyl acrylate, hydroxyethyl methacrylate, vinyl pyrrolidone, ethoxylated (meth) acrylate and (meth) acrylamide.
Suitable ionic vinyl monomers may be cationic.

Preferred anionic vinyl monomers include at least one selected from the group consisting of a carboxyl group, a phosphoric acid group, and a sulfonic acid group (these acids may be free or salts). Preferred examples include (meth) acrylic acid, styrene sulfonic acid, vinyl benzyl sulfonic acid, vinyl sulfonic acid, (meth) acryloyloxyalkyl sulfonic acid (for example, acryloyloxymethyl sulfonic acid, acryloyloxyethyl sulfonic acid, acryloyloxypropyl sulfone). Acid, acryloyloxybutylsulfonic acid, methacryloyloxymethylsulfonic acid, methacryloyloxyethylsulfonic acid, methacryloyloxypropylsulfonic acid, methacryloyloxybutylsulfonic acid), 2-acrylamide-2-alkylalkanesulfonic acid (for example, 2-acrylamide- 2-methylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylbutanesulfonic acid), -Methacrylamide-2-alkylalkanesulfonic acid (eg 2-methacrylamide-2-methylethanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylbutanesulfonic acid), Mono (acryloyloxyalkyl) phosphate (eg, mono (acryloyloxyethyl) phosphate, mono (3-acryloyloxypropyl) phosphate), mono (methacryloyloxyalkyl) phosphate (eg, mono (methacryloyloxyethyl) phosphate Salt, mono (3-methacryloyloxypropyl) phosphate).
Preferred cationic vinyl monomers are those containing quaternary ammonium groups, pyridinium groups, guanidinium groups or biguanidinium groups.
Preferred hydrophobic vinyl monomers do not have hydrophilic groups. Preferred hydrophobic vinyl monomers include C _1-20 -hydrocarbyl (meth) acrylate, butadiene, styrene and vinyl naphthalene, such as C _1-20 -hydrocarbyl (meth) acrylate (eg, methyl (meth) acrylate, butyl ( (Meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate) Methyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and phenoxyethyl methacrylate are particularly preferable. These hydrocarbyl groups may be branched but are preferably linear.

Polyesters having at least one carboxyl group are also produced by reaction of a diol monomer with an excess of dicarboxylic acid monomer. The carboxyl group can also be introduced by copolymerization of a diol having a carboxyl group and a dicarboxylic acid monomer.
Polyesters are typically made by esterification of a dicarboxylic acid and a diol.
A polyester having a carboxyl group can be produced, for example, by subjecting a carboxyl group-containing compound and a hydroxyl group-containing compound to a dehydration condensation reaction by a known method such as a melting method or a solvent method so that the carboxyl group remains. it can.
Examples of the polyester include those obtained by appropriately selecting and dehydrating and condensing a compound having a carboxyl group such as a monobasic acid and a polybasic acid and a compound having a hydroxyl group such as a diol and a polyol. Or the thing using fatty acids becomes alkyd resin.

The carboxyl group which the polyester used by this invention has is an unreacted carboxyl group mainly derived from the polybasic acid more than the dibasic acid which comprises polyester.
Examples of polybasic acids include adipic acid, (anhydrous) succinic acid, sebacic acid, dimer acid, (anhydrous) maleic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, tetrahydro (anhydride) phthalic acid, hexahydro ( Anhydrous) phthalic acid, hexahydroterephthalic acid, 2,6-naphthalenedicarboxylic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid and the like.

  Examples of compounds having a carboxyl group that can be used in addition to polybasic acids include lower alkyl esters of acids such as dimethyl terephthalate; monobasic acids such as benzoic acid, p-tertiarybutyl benzoic acid, rosin, and hydrogenated rosin. Acids; fatty acids and oils; macromonomers having one or two carboxyl groups at the molecular terminals; 5-sodium sulfoisophthalic acid and dimethyl esters thereof.

  Examples of the compound having a hydroxyl group include ethylene glycol, neopentyl glycol, propylene glycol, diethylene glycol, dipropylene glycol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1 , 4-butanediol, 1,3-propanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,5-pentanediol, alkylene oxide adduct of bisphenol A, hydrogenated bisphenol A, hydrogenated Alkylene oxide adducts of bisphenol A, diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol; glycerin, trimethylolpropane, trimethylolethane, diglycerin, pentaerythridine Polyols such as lithol and trishydroxyethyl isocyanurate; monoglycidyl compounds such as “Cardura E-10” (a glycidyl ester of a synthetic fatty acid manufactured by Shell Chemical Industry Co., Ltd.), a macro having two hydroxyl groups at one molecular end And monomers.

In addition, when synthesizing polyester, hydroxyl group-containing fatty acids or fats such as castor oil and 12-hydroxystearic acid; compounds having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid, p-hydroxybenzoic acid and ε-caprolactone Can also be used.
Furthermore, a part of the dibasic acid can be replaced with a diisocyanate compound.
A polyester having a carboxyl group can also be produced by a method in which an anhydride such as maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride is added to a hydroxyl group-containing polyester. be able to.
A polyester having a hydroxyl group and a carboxyl group can be easily produced by, for example, reacting a hydroxyl group and a carboxyl group so as to remain in a dehydration condensation reaction of a polyester resin according to a known method.

  Polyester having a tertiary amino group and a carboxyl group is obtained by using a polyester resin, for example, a compound having a tertiary amino group and a hydroxyl group such as triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, etc. It can manufacture easily by using as an alcohol component at the time of manufacture.

  The polyester having a radically polymerizable unsaturated group and a carboxyl group is, for example, a radically polymerizable unsaturated group-containing monomer having an isocyanate group such as 2-methacryloyloxyethyl isocyanate to a polyester having a hydroxyl group and a carboxyl group, or , A method of adding an acid anhydride having a radically polymerizable unsaturated group such as maleic anhydride, a method of adding a polymerizable monomer having an epoxy group to a polyester resin having a carboxyl group, and maleic anhydride as an acid component It can be easily produced by a method of synthesizing a polyester resin using a radical polymerizable unsaturated group-containing monomer such as

Polyurethane is preferably produced by a condensation reaction of a polyisocyanate component (for example, diisocyanate) and a polyol component (for example, diol).
Polyurethane having a carboxyl group can be easily obtained by reacting a polyisocyanate component with a polyol component containing a compound having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid as a component for introducing a carboxyl group. Can be manufactured.
As the polyol component, in addition to the diol component listed in the polyester production method, a trifunctional or higher functional polyol compound may be used as necessary.
Examples of the polyisocyanate component include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, 1,5-naphthalene diisocyanate, and metaxylylene diisocyanate. Diisocyanate compounds such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated 4,4′-diphenylmethane diisocyanate, hydrogenated metaxylylene diisocyanate, crude 4,4′-diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate Isocyanate compounds can also be used.

The polyurethane may be produced by a conventional method. For example, the addition reaction is preferably performed at room temperature or a temperature of about 40 to 100 ° C. in an inert organic solvent solution that does not react with an isocyanate group. At that time, a known catalyst such as dibutyltin dilaurate may be used.
A known chain extender such as diamine, polyamine, N-alkyl dialkanolamine such as N-methyldiethanolamine; dihydrazide compound can be used in the reaction system for producing polyurethane.

A polyurethane having a hydroxyl group and a carboxyl group can be easily produced, for example, by reacting at a ratio that the hydroxyl group is larger than the isocyanate group when producing the polyurethane. Alternatively, it can also be easily produced by subjecting a polyisocyanate having a carboxyl group and a terminal isocyanate group to an addition reaction with a compound having two or more hydroxyl groups in one molecule.
A polyurethane having a tertiary amino group and a carboxyl group can be easily produced, for example, by using an N-alkyl dialkanolamine such as N-methyldiethanolamine as a part of the polyol component.
A polyurethane having a blocked isocyanate group and a carboxyl group can be easily produced by, for example, adding a known blocking agent to a polyisocyanate having a carboxyl group and a terminal isocyanate group.
A polyurethane having an epoxy group and a carboxyl group can be easily produced by, for example, adding a compound having a hydroxyl group and an epoxy group to a polyisocyanate having a carboxyl group and a terminal isocyanate group.
Examples of the compound having a hydroxyl group and an epoxy group include glycidol, glycerin diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl ether of bisphenol A, and the like.

  Polyurethane having a radical polymerizable unsaturated group and a carboxyl group as an acidic group is, for example, a polyisocyanate having a terminal isocyanate group, a polymerizable monomer having a hydroxyl group as described above, glycerol mono (meth) acrylate, and trimethylol. It can be easily produced by a method in which a compound having a hydroxyl group and a radically polymerizable unsaturated group such as propanedi (meth) acrylate or pentaerythritol triacrylate is subjected to an addition reaction.

  A polyurethane having a hydrolyzable alkoxysilane group and a carboxyl group as an acidic group is, for example, a polyisocyanate having a terminal isocyanate group, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-aminopropyltrimethyl. It can be easily produced by a method of adding a silane coupling agent having an active hydrogen capable of reacting with an isocyanate group such as methoxysilane and γ-aminopropyltriethoxysilane.

  The polymer is selected to match the dispersion medium used and to match the liquid color developer (vehicle) in the final composition used (eg, ink composition). For example, when the aqueous pigment dispersion is used in an aqueous inkjet recording ink composition, the polymer is preferably hydrophilic.

  Commercially available dispersants may be used as long as they can be used in aqueous systems and are not significantly colored. For example, SOLPERSE 20000, SOLPERSE 27000, SOLPERSE 41000, which are SOLSEPERSE (registered trademark) series manufactured by Nippon Lubrizol Corporation. , SOLPERSE41090, SOLPERSE43000, SOLPERSE44000, SOLPERSE54000; DISPERBYK-180 series, DISPERBYK-181, DISPERBYK-182, DISPERBYK-183, DISPERBYK-183, DISPERBYK-183, DISPERBYK-183, 84 DISPERBYK 190, DISPERBYK-191, DISPERBYK-192, DISPERBYK-193, DISPERBYK-194, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2013, DISPERBYK-2015, DISPERBYK-2055, DISPERBYSP-20K, SPPERBYSP-20K DISPERBYK-2091, DISPERBYK-2095, DISPERBYK-2096; EFKA (registered trademark) series EFKA 4500, EFKA 4510, EFKA 4520, EFKA 4550, EFKA 4560, EFKA 4570, EFKA 4570, EFKA 4570, EFKA 4570, EFKA 4570 E KA 4800, EFKA 5071, EFKA 6220, EFKA 6225, EFKA 6230, Dispex can be used (TM) Ultra PX 4575, and the like.

In the aqueous pigment dispersion of the present invention, the content of the azo pigment represented by the formula (1) is P, the content of the dispersant is D, and the ratio of the content D to the content P is the D / P value. D / P value is preferably 0.1 or more and 0.8 or less, more preferably 0.2 or more and 0.75 or less, and 0.3 or more and 0.7 or less. Further preferred.
The ratio of the content of the azo pigment represented by formula (1) of the aqueous pigment dispersion of the present invention P, and the content of the first dispersant and D ^1, the content P and the content D ¹ ( When the mass ratio is D ¹ / P value, the D ¹ / P value is preferably 0.05 or more and 1.2 or less, more preferably 0.1 or more and 0.8 or less, More preferably, it is 0.2 or more and 0.75 or less, and particularly preferably 0.3 or more and 0.7 or less. Within the above range, the storage stability is more excellent.
The ratio of the content of the azo pigment represented by formula (1) of the aqueous pigment dispersion of the present invention P, and the content of the second dispersion agent and D ^2, and the content P and the content D ² ( When the mass ratio is D ² / P value, the D ² / P value is preferably 0.05 or more and 1.2 or less, more preferably 0.1 or more and 0.8 or less, More preferably, it is 0.2 or more and 0.75 or less, and particularly preferably 0.3 or more and 0.7 or less. Within the above range, the storage stability is more excellent.
The mass ratio of the first dispersant content D ¹ and the second dispersant content D ² in the aqueous pigment dispersion of the present invention is D ¹ : D ² = 5: 1 to 1. : 5, preferably 3: 1 to 1: 3, and more preferably 1: 2 to 2: 1. Within the above range, the storage stability is more excellent.
The total content of the first dispersant and the second dispersant in the aqueous pigment dispersion of the present invention is 10 to 90 parts by mass with respect to 100 parts by mass of the azo pigment represented by the formula (1). It is preferably 10 to 80 parts by mass, more preferably 20 to 75 parts by mass, and particularly preferably 30 to 70 parts by mass.

The aqueous pigment dispersion of the present invention may contain a dispersant other than the first dispersant and the second dispersant.
When the other dispersant is contained, the other dispersant is a dispersant having an amine value of 5 mgKOH / g or more and an amine value> acid value, or a long-chain fatty acid salt or an acid value of 5 mgKOH / g. It is preferable that the dispersant has an acid value ≧ an amine value. When the other dispersant is not the above-described dispersant, the total content of the first dispersant and the second dispersant may be 50% by mass or more based on the total mass of the dispersant in the aqueous pigment dispersion. Preferably, it is 70 mass% or more, and it is still more preferable that it is 90 mass% or more.

<Water>
The aqueous pigment dispersion of the present invention contains water as a dispersion medium.
The water may be tap water or well water, and is not particularly limited. For example, pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water is preferable. Furthermore, it is also preferable to use water sterilized by ultraviolet treatment, hydrogen peroxide treatment or the like for the purpose of preventing the generation of molds and bacteria.

In the present invention, the aqueous pigment dispersion may contain an organic solvent in addition to the above water. In addition, it is preferable that the amount of the organic solvent contained is less than the content of water, and the content of the organic solvent is less than 100 parts by mass with respect to 100 parts by mass of water contained in the aqueous pigment dispersion. Preferably, it is 50 parts by mass or less, more preferably 30 parts by mass or less, particularly preferably 10 parts by mass or less, and most preferably not contained.
The organic solvent used in combination is preferably a water-soluble organic solvent, such as ethanol, methanol, butanol, propanol, isopropanol and other C1-C4 alkyl alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol. Monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, Ethylene glycol mono-t-butyl ether, diethylene glycol mono- -Glycol ethers such as butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, 2-pyrrolidone , Formamide, acetamide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin, sulfolane and the like. These may be used alone or in combination of two or more.

<Other ingredients>
The aqueous pigment dispersion of the present invention may contain other components in addition to the azo pigment represented by the formula (1), the first dispersant, the second dispersant, and water.
Examples of other components include preservatives and polyvalent ions.

<Preservative>
The preservative will be described. In the present invention, the preservative means a substance having a function of preventing the generation and growth of microorganisms, particularly bacteria and fungi.
Various preservatives that can be used in the present invention can be used.
Examples of the preservative include inorganic preservatives (such as silver ion-containing substances) and salts containing heavy metal ions. Organic preservatives include quaternary ammonium salts (tetrabutylammonium chloride, cetylpyridinium chloride, benzyltrimethylammonium chloride, etc.), phenol derivatives (phenol, cresol, butylphenol, xylenol, bisphenol, etc.), phenoxyether derivatives (phenoxyethanol) Etc.), heterocyclic compounds (benzotriazole, proxel, 1,2-benzisothiazolin-3-one, etc.), acid amides, carbamic acid, carbamates, amidine / guanidine, pyridines (sodium pyridinethione- 1-oxide, etc.), diazines, triazines, pyrrole / imidazoles, oxazoles / oxazines, thiazoles / thiadiazines, thioureas, thiosemicarbazides , Dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics (penicillin, tetracycline, etc.), sodium dehydroacetate, sodium benzoate, ethyl p-hydroxybenzoate, and salts thereof Things can be used.
In addition, as preservatives, those described in the antibacterial and microscopic handbook (Gihodo Publishing Co., Ltd .: 1986), the antibacterial and antifungal encyclopedia (edited by the Japanese Society for Antibacterial and Fungal Sciences) Can do.

As these compounds, various compounds such as oil-soluble structures and water-soluble structures can be used, but water-soluble compounds are preferred.
As the preservative, a phenol derivative or a heterocyclic compound is preferable, and a heterocyclic compound is more preferable.
The heterocyclic compound is preferably a thiazole compound or a benzotriazole compound. Among the antiseptics, thiazole compounds particularly function as antifungal agents. Examples of thiazole compounds include benzisothiazoline, isothiazoline, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2- (thiocyanomethylthio) benzthiazole, 2- Examples include mercaptobenzthiazole and 3-allyloxy-1,2-benzisothiazole-1,1-oxide. Moreover, as a thiazole type antifungal agent, Proxel (trademark) series (BDN, BD20, GXL, LV, XL2, Ultra10, etc.) manufactured and sold by Arch Chemicals can also be used.

  A benzotriazole-based compound functions as a rust preventive agent, among other antiseptics. For example, a metal material (particularly 42 alloy (a nickel-iron alloy containing 42% nickel)) constituting an ink jet head is in contact with ink. Rust generation, one of the causes, can be prevented. Examples of the benzotriazole compounds include 1H-benzotriazole, 4-methyl-1H-benzotriazole, 5-methyl-1H-benzotriazole, and sodium salts or potassium salts thereof.

One or more preservatives can be added to the aqueous solution in combination.
The preservative is preferably at least one selected from the group consisting of heterocyclic compounds, phenol derivatives, phenoxy ether derivatives, and alkanediols, and at least one preservative is a heterocyclic compound. Is more preferable.
More preferably, the preservative is a heterocyclic compound, and the heterocyclic compound is a thiazole compound or a benzotriazole compound.

  The content of the preservative in the aqueous pigment dispersion can be used in a wide range, but is preferably 0.01 to 20% by mass relative to the azo pigment represented by the formula (1), 10 mass% is more preferable and 0.5-5 mass% is still more preferable. By setting the content of the preservative within the above range, there is an effect of suppressing the growth of bacteria in the aqueous solution.

<Multivalent metal ion>
The aqueous pigment dispersion of the present invention may contain a polyvalent metal ion.
Examples of the polyvalent metal ion in the present invention include Fe ³⁺ , Fe ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Cd ²⁺ , Ni ²⁺ , Zn ²⁺ and Cu. ²⁺ , Co ²⁺ , Pb ²⁺ , Mn ²⁺ , Al ³⁺ , Cr ³⁺ , Sn ^{4+ and the} like.
The content of polyvalent metal ions in the aqueous pigment dispersion is preferably 10 ppm or less, more preferably 0.001 to 5 ppm. By setting the content of polyvalent metal ions in the aqueous pigment dispersion to the amount specified above, the pigment and / or dispersant in the aqueous pigment dispersion of the present invention suppresses the increase of coarse particles due to aggregation. can do.

(Coloring composition)
The coloring composition of the present invention contains the aqueous pigment dispersant of the present invention.
The coloring composition of the present invention may contain other additives as necessary within a range that does not impair the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, anti-mold agents, pH adjusters, surface tension adjusters, antifoaming agents, Known additives (described in JP-A No. 2003-306623) such as a viscosity modifier, a dispersant, a dispersion stabilizer, a rust inhibitor, and a chelating agent can be used. These various additives are directly added to the ink liquid in the case of water-soluble ink.

  Examples of the coloring composition using the aqueous pigment dispersion obtained in the present invention include water-based paints such as automobiles, coated steel plates, building materials, and cans, printing agents for dyeing fibers, water-based inks such as gravure inks and flexographic inks, Water-based ballpoint pens, fountain pens, water-based sign pens, inks for writing instruments such as water-based markers, water-based recording liquids for on-demand type ink jet printers such as bubble jet (registered trademark), thermal jet, and piezo methods Examples of color filter dispersions used in personal computers are not limited to these applications.

  The colored composition includes an aqueous pigment dispersion obtained by the present invention, a film-forming resin, its curing agent, various auxiliary agents, an organic solvent, water, a basic substance, various pigments, and the like depending on its use. Conveniently selected and mixed.

  The content ratio of the aqueous pigment dispersion obtained by the present invention in the coloring composition is preferably 50% by mass or less, particularly preferably in the range of 0.1 to 40% by mass in terms of pigment. When the ratio of the pigment exceeds 50% by mass, the viscosity in the colored composition tends to be high, and the object to be coated tends not to be colored.

  Examples of the film-forming resin include natural proteins such as glue, gelatin, casein, albumin, gum arabic, and fish mulberry, alginic acid, methylcellulose, carboxymethylcellulose, polyethylene oxide, hydroxyethylcellulose, polyvinyl alcohol, polyacrylamide, and aromatic amide. , Synthetic polymers such as polyacrylic acid, polyvinyl ether, polyvinyl pyrrolidone, acrylic resin, polyester, alkyd resin, urethane resin, amide resin, melamine resin, ether resin, fluorine resin, styrene acrylic resin, styrene maleic acid resin, photosensitivity Common materials such as a resin, a thermosetting resin, an ultraviolet curable resin, and an electron beam curable resin are exemplified, but the invention is not particularly limited thereto. These are selected and used depending on the use of the coloring composition.

  The ratio of these coating film-forming resins in the colored composition is preferably in the range of 0 to 50% by mass. Depending on the application, the resin component in the dispersant used in the aqueous pigment dispersion acts as a resin for forming a coating film, or an application that does not require a resin for coating, such as a recording liquid The coating composition-forming resin is not necessarily required in the coloring composition.

  Examples of the curing agent for the film-forming resin include amino resins such as melamine resin, benzoguanamine resin and urea resin, phenol resins such as trimethylolphenol and its condensate, tetramethylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI). , Hexamethylene diisocyanate (HDI), naphthalene diisocyanate (NDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), polyisocyanates such as modified and blocked isocyanates, aliphatic amines, aromatic amines, N- Amines such as methylpiperazine, triethanolamine, morpholine, dialkylaminoethanol, benzyldimethylamine, polycarboxylic acid, phthalic anhydride, maleic anhydride Acid anhydrides such as hexahydrophthalic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, bisphenol A type epoxy resin, phenolic epoxy resin, glycidyl methacrylate copolymer, glycidyl carboxylic acid Ester resins such as ester resins, alicyclic epoxies, polyether polyols, polybutadiene glycols, polycaprolactone polyols, alcohols such as trishydroxyethyl isocyanate (THEIC), peroxide radical curing, or unsaturated for UV curing and electron beam curing. Examples of the group-containing compound include polyvinyl compounds, polyallyl compounds, vinyl compounds such as a reaction product of glycol or polyol and acrylic acid or methacrylic acid.

  Although a hardening | curing agent is suitably selected and used by a use or aptitude, it may not be used. The use ratio of the curing agent is preferably in the range of 0 to 50% by mass and particularly preferably in the range of 0 to 40% by mass with respect to 100% by mass of the film-forming resin.

  Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, n-propyl alcohol, and isopropyl alcohol; amides such as dimethylformaldehyde and dimethylacetamide; acetone, Ketones such as methyl ethyl ketone; Ethers such as tetrahydrofuran, dioxane, ethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether; ethylene glycol, propylene glycol , Butylene glycol, triethylene glycol, 1,2,6 Hexane triol, thiodiglycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polyhydric alcohols such as glycerin; N- methyl - pyrrolidone, 1,3-dimethyl-2-imidazolidinone. Of these water-soluble organic solvents, polyhydric alcohols and ethers are preferred.

  The content of the organic solvent in the aqueous coloring liquid is preferably 50% by mass or less, and particularly preferably in the range of 0 to 30% by mass. Needless to say, it is preferable that the aqueous coloring liquid is not inferior in terms of environmental problems unless the performance of the aqueous coloring liquid is inferior.

Auxiliaries used as necessary include dispersion wetting agents, anti-skinning agents, UV absorbers, antioxidants, preservatives, fungicides, pH adjusters, viscosity adjusters, chelating agents, surfactants And various auxiliary materials and stabilizers such as, but not limited to.
Examples of basic substances include inorganic compounds such as sodium hydroxide and potassium hydroxide; ethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-ethyldiethanolamine, 2-amino-2-methylpropanol, 2 Examples include, but are not limited to, organic amine compounds such as ethyl-2-amino-1,3-propanediol, 2- (aminoethyl) ethanolamine, tris (hydroxymethyl) aminomethane, ammonia, piperidine and morpholine. Is not to be done.

  As a disperser for dispersing the aqueous pigment dispersion of the present invention in these colored compositions, a simple known disperser such as a disper is sufficient, but is not limited thereto.

  As a method for producing a colored composition, the aqueous pigment dispersion of the present invention and a film-forming resin, a curing agent, various auxiliary agents, an organic solvent, water, various pigment compositions, etc. are simply added and mixed. In the case of adding a high-viscosity resin or organic solvent, there is a method in which the aqueous pigment dispersion of the present invention is stirred and the resin, curing agent, organic solvent, and various auxiliaries are sequentially added therein. More preferred.

  Moreover, the coloring composition containing the aqueous pigment dispersion liquid obtained by this invention can be manufactured according to the use. Furthermore, storage stability, solvent stability required for the coloring composition, performance such as hydrophilicity to prevent clogging of the nozzle at the tip of the writing instrument, water resistance, weather resistance, transparency, sharpness, etc. It is possible to provide the performance of the coating film excellent in various aptitudes.

(Ink composition)
The ink composition of the present invention is an ink composition using the aqueous pigment dispersant of the present invention as a raw material, and preferably contains the aqueous pigment dispersion of the present invention.
It does not specifically limit as an ink composition, What is necessary is just to use the coloring composition mentioned above for an ink use suitably. Specifically, water-based inks such as gravure inks and flexo inks, water-based ballpoint pens, fountain pens, water-based sign pens, inks for writing tools such as water-based markers, bubble-jet (registered trademark) methods, thermal jet methods, piezo methods, and other on-demand types It can be used as ink for inkjet printers.
Among these, the ink composition of the present invention is suitable as an ink composition for inkjet recording.

  In the ink composition for ink jet recording to which the aqueous pigment dispersion of the present invention is applied, the average particle diameter (Mv) of the pigment is preferably in the range of 20 to 250 nm, and more preferably in the range of 20 to 100 nm. . If the average particle diameter of the pigment is 20 nm or more, the dispersion stability is improved, so that good storage stability and ejection stability can be obtained, and a high OD value of the recorded matter can be secured. Moreover, if the average particle diameter of a pigment is 250 nm or less, nozzle clogging can be prevented and sedimentation of a resin adsorbing the pigment can also be suppressed.

  The ink composition for ink jet recording is produced using the aqueous pigment dispersion of the present invention, and the pigment content relative to the total amount of the ink composition is preferably in the range of 2 to 15% by mass. If the pigment content is 2% by mass or more, a high OD value of the recorded matter can be secured. In addition, when the pigment content is 15% by mass or less, it is easy to match the ink jet proper physical property value, and it is possible to secure better storage stability and ejection stability.

Moreover, the ink composition for inkjet recording can also use an organic solvent together with water as a solvent. Such an organic solvent has compatibility with water, improves the permeability of the ink composition into the recording medium and the nozzle clogging, and dissolves the components in the ink composition such as a penetrant described later. What improves the is preferable.
For example, C1-C4 alkyl alcohols such as ethanol, methanol, butanol, propanol, isopropanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol Monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether 1-methyl-1-methoxybuta , Glycol ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, 2-pyrrolidone, formamide, acetamide, dimethyl sulfoxide, sorbit Sorbitan, acetin, diacetin, triacetin, sulfolane and the like. One or more of these solvents can be used in the ink composition of the present invention, preferably at 0 to 10% by mass.

The ink composition for inkjet recording preferably contains a surfactant from the viewpoint of improving the printing quality.
The surfactant can be selected from commonly used anionic surfactants, cationic surfactants, amphoteric surfactants and nonionic surfactants, and among these, nonionic surfactants are particularly preferred.
Specific examples of nonionic surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene phenyl ethers, and the like. An ink composition with less foaming compared to the surfactant can be obtained. Furthermore, among nonionic surfactants, acetylene glycol surfactants are particularly preferred when used in ink jet recording because an ink composition with little foaming can be obtained.
Examples of such acetylene glycol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 3,6-dimethyl-4-octyne-3,6-diol. 3,5-dimethyl-1-hexyn-3-ol, or substances obtained by adding an average of 1 to 30 ethyleneoxy groups or propyleneoxy groups to each of a plurality of hydroxyl groups in each of these substances.
Moreover, as an acetylene glycol type surfactant, a commercial item can also be used, for example, "Orphine E1010" and "Orphine STG" (above, Nissin Chemical Industry Co., Ltd. product) etc. are mentioned. These 1 type (s) or 2 or more types can be used.
The content of the acetylene glycol surfactant is preferably 0.1 to 3% by mass, more preferably 0.5 to 1.5% by mass in the ink composition of the present invention.

The ink composition for ink jet recording preferably contains a penetrating agent in order to further improve the fixing property to the recording medium and to improve the abrasion resistance of the recorded image.
Such penetrants include glycols such as diethylene glycol mono-n-butyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, and dipropylene glycol mono-n-butyl ether. Ethers are preferred, and diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, and dipropylene glycol mono-n-butyl ether are particularly preferred from the viewpoints of excellent penetrating performance and easy handling.
The content of the penetrant is 1 to 20% by mass in the ink composition of the present invention in terms of improving the penetrability and quick-drying property of the ink composition and effectively preventing the occurrence of ink bleeding. Preferably, it is 2-10 mass%.

The ink composition for ink-jet recording preferably contains water-soluble glycols in order to prevent nozzle clogging and improve reliability.
Examples of such water-soluble glycols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of 2,000 or less, 1,3- Dihydric alcohols such as propylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, glycerin, Examples thereof include trivalent or higher alcohols such as mesoerythritol and pentaerythritol.
1 type (s) or 2 or more types can be used for water-soluble glycols.
The content of the water-soluble glycol is preferably 1 to 30% by mass in the ink composition of the present invention.

Further, in the ink composition for ink jet recording, like the water-soluble glycols, an antifungal agent or an antiseptic can be contained in order to prevent clogging of the nozzle.
For example, sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazolin-3-one (AVECIA Proxel CRL, Proxel BDN) , Proxel GXL, Proxel XL-2, Proxel TN) and the like.
One or more of these antifungal agents and preservatives can be preferably used in the ink composition of the present invention at 0.01 to 0.5% by mass.

The pH of the ink composition for inkjet recording is preferably 6 to 11, and more preferably 7 to 10 from the viewpoints of improvement in print density and liquid stability. In order to bring the pH of the ink composition within the above range, it is preferable to contain a pH adjusting agent.
Examples of pH adjusters include inorganic alkalis such as sodium hydroxide, potassium hydroxide and lithium hydroxide, tertiary alcohols having 6 to 10 carbon atoms such as ammonia, triethanolamine, ethyldiethanolamine, diethylethanolamine and tripropanolamine. Examples include amines.
One or more pH adjusting agents can be used in the ink composition of the present invention, preferably at 0.01 to 2% by mass.

The inkjet recording method of the present invention includes a step of discharging the inkjet recording ink composition of the present invention onto a recording medium by an inkjet method.
The ink jet recording method of the present invention can use any method in which ink is ejected as droplets from a fine nozzle and the droplets are attached to a recording medium.

  Some of them will be explained. First, there is an electrostatic suction method. In this method, a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, ink is continuously ejected from the nozzle in the form of droplets, and a print information signal is output while the ink droplets fly between the deflection electrodes. There is a method of recording by applying to the deflection electrode, or a method of ejecting ink droplets corresponding to the print information signal without deflecting the ink droplets.

  The second method is a method in which ink droplets are forcibly ejected by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal resonator or the like. The ejected ink droplet is charged simultaneously with the ejection, and a printing information signal is given to the deflection electrode and recorded while the ink droplet flies between the deflection electrodes.

  The third method is a method using a piezoelectric element, in which pressure and a print information signal are simultaneously applied to ink with a piezoelectric element, and ink droplets are ejected and recorded.

  The fourth method is a method in which the ink is rapidly expanded in volume by the action of heat energy, and is a method in which the ink is heated and foamed with a microelectrode in accordance with a print information signal, and ink droplets are ejected and recorded.

  Any of the above methods can be used in an ink jet recording method using an ink composition. By applying the ink composition for ink jet recording of the present invention, excellent ejection stability and nozzle clogging can be realized in any ink jet recording system.

  The recording medium that can be used in the inkjet recording method of the present invention is not particularly limited, and a known recording medium can be used as a support or a recording material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal (eg, aluminum, zinc, copper, etc.) plate, plastic (eg, cellulose diacetate, cellulose triacetate, propionic acid) Cellulose, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the above-mentioned metal is laminated or vapor-deposited. .

  The recorded matter of the present invention is obtained by performing inkjet recording using at least the ink composition of the present invention. By using the ink composition of the present invention, the recorded matter improves the fixability of the ink composition, particularly the pigment in the ink composition, and has excellent density, scratch resistance, glossiness, characters, figures, etc. Images can be formed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the form in these Examples. Unless otherwise specified, “part” and “%” are based on mass.

  The X-ray diffraction of the azo pigment of the present invention is measured using CuKα rays in a powder X-ray diffraction measurement device RINT2500 (manufactured by Rigaku Corporation) in accordance with Japanese Industrial Standards JISK0131 (general rules for X-ray diffraction analysis). This was done under the conditions of

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

[Synthesis Example 1] Synthesis of azo pigment (1) of the present invention A synthesis scheme of azo pigment (1) is shown below.

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

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

(3) Synthesis of Intermediate (c) 298 mL of methanol was added to 387 mL (7.98 mol) of hydrazine monohydrate and cooled to 10 ° C. (internal temperature), and 149 g of 4,6-dichloropyrimidine was added to this mixed solution ( 1.00 mol) was gradually added (internal temperature 20 ° C. or lower), the ice bath was removed, the temperature was raised to room temperature, and the mixture was stirred at the same temperature for 30 minutes. Thereafter, the mixture was further heated to raise the internal temperature to 60 ° C. and stirred at the same temperature for 5 hours. After completion of the reaction, 750 mL of water was added, and the mixture was cooled with ice until the internal temperature reached 8 ° C. The precipitated crystals were collected by filtration, rinsed with water, and rinsed with isopropanol. It dried at room temperature for 36 hours, and obtained the said intermediate body (c) by 119g (white powder, yield 84.5%). The NMR measurement result of the obtained intermediate (c) is as follows.
¹ H-NMR (300 MHz, d-DMSO) 7.80 (s, 1H), 7.52 (s, 2H), 5.98 (s, 1H), 4.13 (s, 4H)

(4) Synthesis of intermediate (d) To 50 g (357 mmol) of intermediate (c), 128 mL of water was added and stirred at room temperature. To this suspension, 98.2 g (785 mmol) of pivaloylacetonitrile was added, and 12 M hydrochloric acid aqueous solution was added dropwise at the same temperature so that the pH became 3, and then the mixture was heated to an internal temperature of 50 ° C. For 6 hours. After completion of the reaction, the solution was neutralized by adding 8N aqueous potassium hydroxide solution to pH 6.4. The mixture was cooled with ice and cooled to an internal temperature of 10 ° C., and the precipitated crystals were collected by filtration and washed with water. The obtained crystal was dried at 60 ° C. under reduced pressure, and 30 mL of toluene was added to the obtained crude product, and heated to 60 ° C. for dissolution. The resulting solution was allowed to stand at room temperature for 12 hours, and the precipitated crystals were collected by filtration, washed with cooled toluene and dried at 60 ° C. under reduced pressure, and 87.7 g of the intermediate (d) (white powder) Yield 69.3%). The NMR measurement result of the obtained intermediate (d) is as follows.
¹ H-NMR (300 MHz, d-DMSO) 8.74 (s, 1H), 7.99 (s, 1H), 6.87 (s, 4H), 5.35 (s, 2H), 1.24 (s, 18H)

  (5) Synthesis of azo pigment (1)

  In a mixed solution of 55 mL of acetic acid and 37 mL of propionic acid, 9.2 g of intermediate (b) was dissolved at room temperature. The inner temperature was cooled to -3 ° C by cooling with ice, and a 40 mass% sulfuric acid solution of nitrosylsulfuric acid was added dropwise over 10 minutes at an inner temperature of -3 ° C to 4 ° C. After stirring for 1 hour at an internal temperature of 4 ° C., 0.2 g of urea was added, and then the internal temperature was cooled to −3 ° C. and further stirred for 10 minutes to obtain a diazonium salt solution. Separately, 10 g of intermediate (d) was completely dissolved in 150 mL of acetone, then the internal temperature was cooled to 17 ° C., and added to the above diazonium salt solution over 25 minutes within the range of the internal temperature of −3 ° C. to 3 ° C. . After completion of the addition, the mixture was stirred at 3 ° C. for 30 minutes, then the ice bath was removed and the temperature was raised to room temperature over 30 minutes. After stirring at room temperature for 30 minutes, the obtained crystals were separated by filtration, washed with 150 mL of acetone, and further washed with 100 mL of water. The obtained crystals were suspended in 400 mL of water without drying, and an 8N aqueous potassium hydroxide solution was added to adjust the pH to 5.7. After stirring at room temperature for 20 minutes, the obtained crystals were separated by filtration, thoroughly washed with water, and then washed with 80 mL of acetone. The obtained crystal was dried at room temperature for 12 hours.

  The obtained crystals were suspended in 580 mL of acetone and then stirred for 30 minutes under reflux. Thereafter, the mixture is cooled to room temperature over 10 minutes, and the obtained crystals are filtered off and dried at room temperature for 5 hours. The azo pigment (1) represented by the formula (1) having the crystal form of the present invention is 17 0.1 g was obtained. Yield 88.5%. When the obtained azo pigment (1) was visually observed with a transmission microscope (manufactured by JEOL Ltd .: JEM-1010 electron microscope), the length of the primary particles in the major axis direction was about 15 μm. It was. When the X-ray diffraction measurement of the azo pigment (1) was performed under the above conditions, characteristic X-ray diffraction peaks were observed at Bragg angles (2θ ± 0.2 °) of 7.6 ° and 25.6 °. Indicated. A CuKα characteristic X-ray diffraction diagram is shown in FIG.

    EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the form in these Examples. Unless otherwise specified, “part” and “%” are based on mass.

<Measurement method of particle diameter in pigment dispersion>
The particle diameter in the pigment dispersion was measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.

<Production of Aqueous Pigment Dispersion AA>
As a specific pigment, 15.0 parts of the azo pigment (1), 7.5 parts of EFKA4585 (solid content concentration: 50% by mass) manufactured by BSF Corporation as a dispersant 1, and 82.0 parts of water Were dispersed together with 375 parts of zirconia beads having a diameter of 0.1 mm using a sand grinder mill TSG1 (manufactured by Imex) at 1,500 rpm and 45 ° C. Note that the solid content concentration of ˜50% means that the solid content concentration is about 50%, and the same applies to the solid content concentration in the description described below and the solid content concentrations in Tables 2 to 6. It is. After dispersion until the volume average particle diameter Mv was 100 nm or less, zirconia beads were separated to obtain 95 parts of an aqueous pigment dispersion AA having a pigment concentration of 14.2%. It took 3 hours until the volume average particle diameter Mv became 100 nm or less.

<Production of aqueous pigment dispersion 1>
While stirring 20 parts of the aqueous pigment dispersion AA, 1.1 parts of DISPERBYK181 (solid content concentration: ~ 63%) manufactured by Big Chemie Co., Ltd. and 6.7 parts of water were used as the dispersant 2. Was slowly added and stirred at room temperature for 1 hour to obtain an aqueous pigment dispersion 1 having a pigment concentration of 10.2% by mass. The content of the azo pigment in the aqueous pigment dispersion is P, the total content of the first dispersant and the second dispersant is D, and the ratio (mass ratio) between the content D and the content P is D / When P, D / P = 0.5. In addition, D / P in Table 2-Table 6 described below is also the value calculated similarly.

<Production of aqueous pigment dispersions 2-9>
Aqueous pigment dispersions 2 to 9 were produced in the same manner as in the production of the aqueous pigment dispersion 1, except that the dispersant 2 used in the production of the aqueous pigment dispersion 1 was changed to the compounds shown in Table 2 below. .

<Production of aqueous pigment dispersions 10-11>
The aqueous pigment dispersion liquid 10 was obtained by heating the aqueous pigment dispersion liquid 1 at 60 ° C. for 1 hour. Similarly, the aqueous pigment dispersion 11 was obtained by heating the aqueous pigment dispersion 3 at 60 ° C. for 1 hour.

<Production of aqueous pigment dispersion 12>
To 8 parts of the aqueous pigment dispersion 1, 0.4 part of an ion exchange resin (Amberlite MB-2 manufactured by Organo Corporation) was added and stirred for about 4 hours, and the electrical conductivity was adjusted to 10 μS / cm or less. The ion exchange resin was removed. Thereafter, triisopropanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9.0 to obtain an aqueous pigment dispersion 12.

<Production of aqueous pigment dispersion 13>
To 8 parts of the aqueous pigment dispersion 2, 0.4 part of an ion exchange resin (Amberlite MB-2 manufactured by Organo Corporation) was added and stirred for about 4 hours, and the electrical conductivity was adjusted to 10 μS / cm or less. The ion exchange resin was removed. Thereafter, triisopropanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9.0 to obtain an aqueous pigment dispersion 13.

<Production of aqueous pigment dispersions AB to AI>
Similar to the production of the aqueous pigment dispersion AA, except that the dispersant 1 used in the production of the aqueous pigment dispersion AA was changed to the compounds described in Table 3 below, the aqueous pigment dispersion A- B to A-I were produced.

<Production of aqueous pigment dispersions 14 to 24>
The aqueous pigment dispersion AA and the dispersant 2 used in the production of the aqueous pigment dispersion 1 were changed to the compounds shown in Table 4 below, except that the aqueous pigment dispersion 1 was used. Dispersions 14-24 were produced.

<Production of aqueous pigment dispersion 25>
The aqueous pigment dispersion liquid 24 was heated at 50 ° C. for 1 hour to obtain an aqueous pigment dispersion liquid 25.

<Production of aqueous pigment dispersion 1 for comparison>
In the production of the aqueous pigment dispersion 1, the azo pigment (1) was changed to P.I. Y. Comparative aqueous pigment dispersion 1 was obtained in the same manner in place of 74 (Pigment Yellow 74, manufactured by Dainichi Seika Co., Ltd.).

<Synthesis of fine azo pigment (2)>
The obtained azo pigment (1) was subjected to salt milling to obtain a fine azo pigment (2) having a primary particle length of 0.03 μm. Salt milling was performed by the following method.
The azo pigment (1) and sodium chloride were put into a supermixer and mixed so as to have the following composition. Diethylene glycol was added little by little while rotating the supermixer to prepare a mixture (hereinafter sometimes referred to as “preliminary mixture”).
・ Azo pigment (1) ・ ・ ・ 150 parts ・ Salt (Oshiomicron T-0 manufactured by Ako Kasei Co., Ltd.) ・ ・ ・ 1,500 parts ・ Diethylene glycol ・ ・ ・ 300 parts Subsequently, a continuous uniaxial kneader ( Asada Iron Works Co., Ltd., Miracle KCK-L), the temperature of 5 parts of the grinding part and the extrusion part is set to 15-20 ° C., the shaft rotation speed is set to 50 rpm, the preliminary mixture obtained above is charged, A kneaded product was obtained. At this time, the current value (load) was about 4 A, the discharge rate was 50 g / min, and the temperature of the discharged material was 16 ° C.
The kneaded material thus obtained was added to 5,000 parts of 1% dilute hydrochloric acid and stirred, and then filtered and washed thoroughly with water to remove sodium chloride and diethylene glycol, followed by drying.

<Production of aqueous pigment dispersions AA ′ to AF ′>
Instead of the azo pigment (1) used in the production of the aqueous pigment dispersion AA, the fine azo pigment (2) was used, and the dispersant 2 was changed to the compounds shown in Table 5 below. Similar to the production of the pigment dispersion 1, aqueous pigment dispersions AA ′ to AF ′ were produced.

<Production of aqueous pigment dispersions 26 to 29>
The aqueous pigment dispersion AA and the dispersant 2 used in the production of the aqueous pigment dispersion 1 were changed to the compounds shown in Table 6 below, except that the aqueous pigment dispersion 1 was used. Dispersions 26-29 were produced.

<Preparation of pigment ink I>
The aqueous pigment dispersions 1 to 29 of the above examples, the comparative aqueous pigment dispersion 1 and the aqueous pigment dispersions AA to A-I each had a total mass of 10.88 parts and a pigment concentration of 6.90 masses. % Of water, and 0.45 part of 2-pyrrolidinone, 2.25 part of glycerol, 0.60 part of 1,2-hexanediol, 0.75 part of ethylene glycol, Surfynol 465 (interface) Activator, manufactured by Nissin Chemical Industry Co., Ltd.), 0.08 part of the mixed solution was added, and the mixture was sufficiently stirred, and pigment inks I-1 to I-29 having a pigment concentration of 5% by mass and comparative pigment ink I-1 And pigment inks IA to I-I were obtained. The evaluation results are shown in Table 7.

<Preparation of Pigment Ink II>
The aqueous pigment dispersions 1 to 29 of the above examples, and the aqueous pigment dispersion 1 and the aqueous pigment dispersions AA to AI of the comparative example, respectively, have a total mass of 11.15 parts and a pigment concentration of 6.73. Water was added so as to be in mass%, and 1.50 parts of triethylene glycol monobutyl ether, 2.25 parts of ethylene glycol, Surfynol 485 (surfactant, manufactured by Nissin Chemical Industry Co., Ltd.), 0 .11 parts of a mixed solution was added and stirred sufficiently to obtain pigment inks II-1 to II-25, comparative pigment ink II-1 and pigment inks II-A to II-I having a pigment concentration of 5% by mass. The evaluation results are shown in Table 7.

(Evaluation)
<Storage stability>
The above aqueous pigment dispersions 1 to 29, comparative aqueous pigment dispersion 1, aqueous pigment dispersions AA to AI, pigment inks I-1 to I-29, and comparative pigment inks I-1 and I -A to I-I, pigment inks II-1 to II-29, comparative pigment ink II-1 and pigment inks II-A to II-I were each allowed to stand at 60 ° C for 4 weeks. The evaluation results are shown in Table 7.

<Viscosity>
The viscosity of the aqueous pigment dispersion and pigment ink that was allowed to stand for 4 weeks (measured under the conditions of 25 ° C. and 100 rpm using a RE80L viscometer manufactured by Toki Sangyo Co., Ltd.) A: More than 5% and less than 10% were evaluated as B, 10% or more and less than 15% as C, and 15% or more as D. The evaluation results are shown in Table 7.

<Particle size>
The volume average particle size of the aqueous pigment dispersion and the pigment ink before and after standing for 4 weeks was measured (measured using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd.). Change rate is within 10% A, change rate is over 10% but less than 15%, change rate is 15% or more and less than 20% C, change rate is 20% or more Evaluated as D.

<Image robustness>
Using the above water-based ink as yellow ink, a commercially available Seiko Epson printer (model number: PX-V630) was used to print on Fuji Photo Film Co., Ltd. photo paper with an OD of 1.0. Atlas The image was irradiated with xenon light (100,000 lux) for 3 weeks using a company-made weather meter. The OD before and after the test was measured with X-rite 310, and the residual ratio of OD was determined and evaluated. The residual ratio was evaluated as A for 90% or more, B for less than 90% and 80% for C, and C for less than 80%. The evaluation results are shown in Table 7.

  Even if the fine azo pigment (1) was used, good results were obtained. Whether the azo pigment (1) not subjected to salt milling or the fine azo pigment (1) subjected to salt milling is used, the aqueous pigment dispersion of the present invention and the pigment ink using the same are as follows: The performance was equivalent.

Claims (11)

Step A is represented by the following formula (1) having a characteristic X-ray diffraction peak at least at a Bragg angle (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction of 7.6 ° and 25.6 °. Mixing at least one of an azo pigment and its tautomer, a first dispersant, and water to produce a mixture;
Step B is a step of dispersing the mixture with a disperser to obtain an aqueous pigment dispersion A, and
A method for producing an aqueous pigment dispersion, comprising, as Step C, a step of adding a second dispersant to the aqueous pigment dispersion A obtained in Step B to obtain an aqueous pigment dispersion in this order .

  The method for producing an aqueous pigment dispersion according to claim 1, wherein at least one of the first dispersant and the second dispersant is a polymer dispersant. The method for producing an aqueous pigment dispersion according to claim 1 or 2, wherein the first dispersant and the second dispersant satisfy any of the following (i) to (iii).
(I) the first dispersant is a long chain fatty acid salt, the total acid value and amine value of the second dispersant is 30 mg KOH / g or more, the amine value is 5 mg KOH / g or more, and the amine (Ii) The sum of the acid value and amine value of the first dispersant is less than 30 mg KOH / g, the amine value is 5 mg KOH / g or more, the amine value is greater than the acid value, and The sum of the acid value and amine value of the second dispersant is 30 mg KOH / g or more, and the acid value is more than the amine value.
(Iii) The sum of the acid value and the amine value of the first dispersant is less than 30 mgKOH / g, the acid value is 5 mgKOH / g or more, the acid value is more than the amine value, and the second dispersant The sum of the acid value and the amine value is 30 mgKOH / g or more, the amine value is 5 mgKOH / g or more, and the amine value is larger than the acid value.   Furthermore, the manufacturing method of the aqueous pigment dispersion liquid of any one of Claims 1-3 including the process which makes the electrical conductivity of an aqueous pigment dispersion liquid 100 microsiemens / cm or less.   The total content of the first dispersant and the second dispersant is 10 to 90% by mass with respect to at least one of the azo pigment represented by the formula (1) and tautomers thereof. Item 5. The method for producing an aqueous pigment dispersion according to any one of Items 1 to 4.   The aqueous pigment dispersion according to any one of claims 1 to 5, wherein at least one of the azo pigment represented by the formula (1) and a tautomer thereof is not salt milled. Production method.   The aqueous pigment dispersion liquid manufactured by the manufacturing method of the aqueous pigment dispersion liquid of any one of Claims 1-6.   A coloring composition containing the aqueous pigment dispersion according to claim 7.   An ink composition comprising the aqueous pigment dispersion according to claim 7 or the coloring composition according to claim 8.   The ink composition according to claim 9, which is an ink composition for inkjet recording. An ink jet recording method comprising a step of discharging the ink composition for ink jet recording according to claim 10 onto a recording medium by an ink jet method.

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