JP2009001633A - Aqueous ink for ink-jet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a water dispersion for ink-jet recording, having an excellent dispersion stability while keeping a weight absorbance and a print density and to obtain an aqueous ink containing the water dispersion obtained by the production method. <P>SOLUTION: The method for producing a water dispersion for ink-jet recording has a process 1 of preparing an azo-based pigment by subjecting a diazo compound and a coupler component to a coupling reaction to give a coupling reaction product and heat-treating the coupling reaction product at 45-100°C, a process 2 of preparing a water dispersion by dispersing the azo-based pigment prepared by the process 1 into an aqueous medium and a process 3 of heat-treating the water dispersion prepared by the process 2 at 43-100°C and at a temperature equal to or lower than the heat treatment temperature in the process 1. The aqueous ink contains the water dispersion prepared by the production method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an aqueous dispersion for ink jet recording, and an aqueous ink for ink jet recording containing an aqueous dispersion obtained by the production method.

The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording member and attaching them. According to this method, not only has the advantage that the device to be used is low noise and good operability, but also has the advantage that colorization is easy and plain paper can be used as a recording member. Widely used in recent years. In recent years, inks used in ink jet printers have become mainstream using pigments or hydrophobic dyes as colorants from the viewpoint of water resistance and weather resistance (see, for example, Patent Document 1).
In Patent Document 1, for the purpose of providing a water-based ink excellent in storage stability, a mixture containing water, a colorant, a water-insoluble polymer, and an organic solvent is dispersed and then the organic solvent is removed. A method for producing a water-based ink for ink-jet recording, comprising a step of obtaining an aqueous dispersion of water-insoluble polymer particles containing a colorant and a step of heat-treating the aqueous dispersion at 40 ° C. or higher is disclosed. However, there is no mention of printing density and weight absorbance when an azo pigment is used as a colorant.

JP 2006-1971 A

  The present invention provides a method for producing an aqueous dispersion for inkjet recording excellent in dispersion stability while maintaining weight absorbance and print density, and an aqueous ink for inkjet recording containing the aqueous dispersion obtained by the production method. Is an issue.

The present inventors have solved the above problem by controlling the heat treatment temperature of the coupling reaction product in the production process of the azo pigment and the heat treatment temperature in the production process of the aqueous dispersion of the pigment. Found to get.
That is, the present invention relates to the following (1) to (3).
(1) A method for producing an aqueous dispersion for inkjet recording, comprising the following steps 1 to 3.
Step 1: A step of obtaining a azo pigment by heat-treating a coupling reaction product obtained by coupling a diazo compound and a coupler component at 45 to 100 ° C. Step 2: The azo obtained in Step 1 Step of dispersing an aqueous pigment in an aqueous medium to obtain an aqueous dispersion of an azo pigment Step 3: The aqueous dispersion obtained in Step 2 is at 43 to 100 ° C. and below the heat treatment temperature in Step 1 Heat treatment step (2) A method for producing an aqueous dispersion for inkjet recording, comprising the following steps 1 to 3.
Step 1: A coupling reaction product obtained by coupling reaction of a diazo compound and a coupler component is heat-treated at 45 to 100 ° C. to contain an azo pigment and an azo pigment derivative having a polar group. Step of obtaining a pigment mixture Step 2: Step of dispersing the azo pigment mixture obtained in Step 1 in an aqueous medium to obtain an aqueous dispersion of the azo pigment mixture Step 3: Water dispersion obtained in Step 2 (3) The aqueous dispersion of the azo pigment obtained by the above (1), or the azo pigment obtained by the above (2), wherein the body is heat-treated at 43 to 100 ° C. and below the heating temperature in the step 1 An aqueous ink for ink-jet recording containing an aqueous dispersion of a mixture.

  According to the production method of the present invention, it is possible to obtain an aqueous dispersion for inkjet recording excellent in dispersion stability while maintaining weight absorbance and printing density, and an aqueous ink containing the aqueous dispersion.

The manufacturing method of the water dispersion for inkjet recording of this invention has the following processes 1-3.
Step 1: A diazo compound and a coupler component are subjected to a coupling reaction, followed by heat treatment at 45 to 100 ° C. to contain an azo pigment or an azo pigment and an azo pigment derivative having a polar group. Step of obtaining a mixture Step 2: Step of dispersing the azo pigment or azo pigment mixture obtained in Step 1 in an aqueous medium to obtain an aqueous dispersion of the azo pigment or azo pigment mixture Step 3: Step 2 The step of heat-treating the aqueous dispersion obtained in step 4 at a temperature of 43 to 100 ° C. and below the heating temperature in step 1 is as follows: The method for producing the aqueous dispersion of the azo pigment of the present invention and the azo type of the present invention Each component used in the method for producing an aqueous dispersion of a pigment mixture will be described in common. In the present specification, a mixture containing an azo pigment and an azo pigment derivative having a polar group is simply referred to as an “azo pigment mixture”.

[Azo pigments]
The azo pigment is a pigment having an azo group in the molecule, and can be obtained by a coupling reaction between a diazo compound and a coupler component as will be described later.
Examples of the azo pigments include yellow azo pigments such as azo lake pigments, insoluble azo pigments, and condensed azo pigments.
Examples of azo lake pigments include acetoacetyl allylide pigments, and more specifically, C.I. I. Pigment yellow 133, 168, 169 and the like.
Examples of insoluble azo pigments include acetoacetate allylide monoazo pigments, acetoacetate allylide disazo pigments, and pyrazolone pigments.
Examples of the acetoacetyl allylide monoazo pigment include Hansa pigments and benzimidazolone pigments. Specifically, examples of the Hansa pigment include C.I. I. Pigment Yellow 1, 2, 3, 5, 6, 49, 63, 65, 73, 74, 75, 87, 90, 97, 98, 106, 111, 114, 116, 121, 124, 126, 127, 130 136, 152, 165, 167, 170, 174, 176, 188 and the like. Examples of benzimidazolone pigments include C.I. I. Pigment yellow 120, 151, 154, 156, 175, 180, 181, 194, and the like.
Examples of acetoacetyl allylide disazo pigments include C.I. I. Pigment yellow 12, 13, 14, 17, 55, 81, 83, 113, 171, 172, and the like.
Examples of the pyrazolone pigment include C.I. I. Pigment yellow 10, 60, and the like.
Examples of condensed azo pigments include C.I. I. Pigment yellow 93, 94, 95, 128, 166 and the like.

Among these, from the viewpoint of improving dispersion stability, insoluble azo pigments are preferable, and among them, acetoacetate allylide monoazo pigments are more preferable. Specifically, C.I. I. Pigment Yellow 74 or 97 is preferable. I. Pigment Yellow 74 is preferable. Azo pigments can be used alone or in admixture of two or more.
The crystallite diameter of the azo pigment is preferably 10 to 200 nm, more preferably 20 to 150 nm, from the viewpoint of improving the color developability. The crystallite diameter is measured using an X-ray diffractometer (manufactured by Rigaku Co., Ltd., microscopic X-ray diffractometer RINT RAPID), X-ray source CuK α, tube voltage 40 kV, tube current 36 mA, transmission diffraction, collimator It can be performed under the conditions of 100 μmΦ and integration for 1 hour.

[Azo-based pigment derivatives having polar groups]
An azo pigment derivative having a polar group (hereinafter simply referred to as a “pigment derivative”) has a function as a surface treatment agent for an azo pigment, and is used to increase the dispersion stability of an aqueous dispersion and an aqueous ink. It is done.
The pigment derivative used in the present invention is obtained by introducing a polar group into an azo pigment. Examples of the polar group include a sulfonic acid group, a carboxy group, a phosphoric acid group, a sulfinic acid group, an amino group, an amide group, and an imide. 1 type or more chosen from the group which consists of groups is mentioned. Among these, a sulfonic acid group is preferable from the viewpoint of dispersion stability.
In addition, the pigment derivative has the same or similar base skeleton (molecular structure) as the azo pigment from the viewpoint of improving the adsorptivity to the surface of the azo pigment to be used, mixing / dispersing stability with the polymer, and hue. It is preferable to have.
Examples of the pigment derivative used in the present invention include one or more azo compounds represented by the following formula (1) from the viewpoint of dispersion stability and the like.

(In the formula, R ¹⁰ and R ^{20 each} represents an optionally substituted aryl group having 6 to 50 carbon atoms, and at least one of them has a polar group. R ¹⁰ or R ²⁰ may be the same or different. May be.)
In formula (1), the aryl group preferably has 6 to 40 carbon atoms, and more preferably 6 to 30 carbon atoms. Moreover, as a preferable substituent, C1-C22, Preferably a C1-C12 alkoxy group, C1-C22, Preferably a C1-C12 alkyl group, an ether group, an ester group, a nitro group a hydroxyl group, a halogen group, an amide group, an amino group, a carboxyl group, a sulfonic acid group, a sulfuric acid group, phosphoric acid group, a phosphonic acid group, a sulfoxide group (-SO-), sulfone group (-SO ₂ -), a triazine group ( And those obtained by removing one or two protons from triazine). In addition, Formula (1) can also be represented by the following Formula (2) as an isomer.

As the azo compound represented by the formula (1), those having a polar group introduced into at least one aryl group as a hydrophilic dispersibility-imparting group are used. Examples of the polar group include the same groups as described above. Among these, from the viewpoint of dispersion stability, —SO ₃ M, —COOM, —SO ₂ M, —RSO ₂ M, —PO ₃ HM, —PO ₃ M (wherein M is a hydrogen atom, R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. 1 type or 2 or more types of functional groups chosen from the group which consists of the functional group represented by these, or its salt are mentioned suitably, A sulfonic acid group is more preferable.

  Specific examples of the azo compound represented by the formula (1) and a method for producing the azo compound are not particularly limited. For example, JP 2003-253188 A, JP 2004-182952 A, and Japanese Patent No. 3055673 Specific examples described in the book, production methods, and the like can be given. Moreover, when introducing a sulfonic acid group as a polar group into an azo pigment, it can be carried out by reacting an azo pigment with a sulfonating agent such as concentrated sulfuric acid, fuming sulfuric acid or chlorosulfuric acid.

  Examples of the pigment derivative used in the present invention include C.I. which is an insoluble azo pigment. I. Pigment yellow 74, C.I. I. A pigment derivative in which a polar group is introduced into CI Pigment Yellow 97 is preferable.

[Azo pigment mixture]
The azo pigment mixture is a mixture containing an azo pigment and an azo pigment derivative having a polar group. The azo pigment and the pigment derivative can be used alone or in admixture of two or more.
From the viewpoint of dispersion stability, color tone and the like, the weight ratio of [pigment derivative / azo pigment] is preferably 0.01 to 0.3, more preferably 0.01 to 0.2, and 0.01 to 0.18. Is more preferable. When the weight ratio is 0.01 or more, the number of adsorption points on the surface of the azo pigment increases and the dispersion stability is improved. On the other hand, if it is 0.3 or less, the pigment derivative that is not adsorbed on the surface of the azo pigment is reduced, and the dispersion stability is improved.
Further, from the viewpoint of dispersion stability, color tone, etc., the molecular weight ratio of [pigment derivative / azo pigment] is preferably 1.4 to 3, more preferably 1.5 to 2.8, and more preferably 1.6 to 2.5. Is more preferable. When the molecular weight ratio is 1.4 or more, the number of adsorption points on the surface of the azo pigment increases and the affinity with a water-insoluble polymer described later is improved, so that the dispersion stability is excellent. On the other hand, when the molecular weight ratio is 3 or less, the pigment derivative that is not adsorbed on the surface of the azo pigment is reduced, and the dispersion stability is improved.
When mixing the azo pigment and the pigment derivative, they may be synthesized and mixed in the same reaction vessel, or the azo pigment and the pigment derivative are synthesized separately, followed by a drying step, a pulverizing step, a classification step, and You may mix in any processes, such as a pigment dispersion process. From the viewpoint of adjusting the primary particle size of the azo pigment and the pigment derivative and enhancing the initial dispersion stability, it is preferable to synthesize both in the same reaction vessel.

(Water-insoluble polymer)
In the present invention, it is preferable to use a water-insoluble polymer in order to disperse the azo pigment mixture in the aqueous medium. Examples of water-insoluble polymers include water-insoluble vinyl polymers, water-insoluble ester polymers, water-insoluble urethane polymers, and the like. Of these, water-insoluble vinyl polymers are preferred. The water-insoluble polymer is a polymer having a dissolution amount of 10 g or less, preferably 5 g or less, more preferably 1 g or less when dissolved in 100 g of water at 25 ° C. after being dried at 105 ° C. for 2 hours. Say. When the water-insoluble polymer has a salt-forming group, the above-mentioned dissolution amount is a dissolution amount when the salt-forming group of the water-insoluble polymer is neutralized 100% with acetic acid or sodium hydroxide, depending on the type.
A water-insoluble vinyl polymer is a polymer obtained by addition polymerization of a vinyl monomer (vinyl compound, vinylidene compound, vinylene compound, etc.), and the main chain is composed of carbon atoms.
Examples of the water-insoluble vinyl polymer include (a) a salt-forming group-containing monomer (hereinafter sometimes referred to as “(a) component”), (b) a macromer (hereinafter sometimes referred to as “(b) component”) and / or (C) A polymer obtained by copolymerizing a monomer mixture (hereinafter sometimes simply referred to as “monomer mixture”) containing a hydrophobic monomer (hereinafter sometimes referred to as “component (c)”) is preferred. More preferably, the water-insoluble vinyl polymer has a structural unit derived from the component (a) or a structural unit derived from the components (a) and (c) in the main chain, and the structural unit derived from the component (b) is a side chain. Is a graft polymer.

(A) The salt-forming group-containing monomer is used from the viewpoint of enhancing the dispersion stability of the resulting dispersion. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group, and a carboxy group is particularly preferable.
Examples of the salt-forming group-containing monomer include a cationic monomer and an anionic monomer. Examples thereof include those described in JP-A-9-286939, page 5, column 7, line 24 to column 8, line 29.
Representative examples of the cationic monomer include unsaturated amine-containing monomers and unsaturated ammonium salt-containing monomers. Among these, N, N-dimethylaminoethyl (meth) acrylate, N- (N ′, N′-dimethylaminopropyl) (meth) acrylamide and vinylpyrrolidone are preferable.

Representative examples of anionic monomers include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and the like.
Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid. Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconic acid ester, and the like. Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxy Examples thereof include ethyl phosphate.
Among the anionic monomers, from the viewpoint of dispersion stability, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable.

The (b) macromer is used from the viewpoint of enhancing the dispersion stability of the polymer particles, particularly when the water-insoluble polymer particles contain an azo pigment or an azo pigment mixture. The macromer includes a macromer which is a monomer having a polymerizable unsaturated group having a number average molecular weight of 500 to 100,000, preferably 1,000 to 10,000. In addition, the number average molecular weight of (b) macromer is measured using polystyrene as a standard substance by gel chromatography using 1 mmol / L dodecyldimethylamine-containing chloroform as a solvent.
Among (b) macromers, styrenic macromers and aromatic group-containing (meth) acrylate macromers having a polymerizable functional group at one end are preferred from the viewpoint of dispersion stability of water-insoluble polymer particles.
Examples of the styrenic macromer include a styrene monomer homopolymer or a copolymer of a styrene monomer and another monomer. Examples of the styrene monomer (b-1) include styrene, 2-methylstyrene, vinyl toluene, ethyl vinyl benzene, vinyl naphthalene, chlorostyrene, and the like.

Examples of the aromatic group-containing (meth) acrylate-based macromer include a homopolymer of an aromatic group-containing (meth) acrylate or a copolymer thereof with another monomer. The aromatic group-containing (meth) acrylate (b-2) may have a substituent containing a hetero atom, and has 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, and more preferably 6 carbon atoms. An arylalkyl group having 12 to 12 carbon atoms, or an aryl group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, and more preferably 6 to 12 carbon atoms, which may have a substituent containing a hetero atom. (Meth) acrylate etc. are mentioned. In addition, examples of the substituent containing a hetero atom include a halogen atom, an ester group, an ether group, and a hydroxy group. Examples include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, and benzyl (meth) acrylate is particularly preferable.
The polymerizable functional group present at one end of the macromer is preferably an acryloyloxy group or a methacryloyloxy group, and the other monomer to be copolymerized is preferably acrylonitrile.
The content of the styrene monomer (b-1) in the styrene macromer or the aromatic group-containing (meth) acrylate (b-2) in the aromatic group-containing (meth) acrylate macromer is the same as that of the azo pigment. From the viewpoint of increasing the affinity, it is preferably 50% by weight or more, more preferably 70% by weight or more.

(B) The macromer may have a side chain composed of another structural unit such as an organopolysiloxane. This side chain can be obtained, for example, by copolymerizing a silicone macromer having a polymerizable functional group at one end represented by the following formula (3).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _{t -Si (CH 3) 3 (} 3)
(In the formula, t represents a number of 8 to 40.)
Examples of commercially available styrenic macromers as component (b) include Toa Gosei Co., Ltd. trade names, AS-6 (S), AN-6 (S), HS-6 (S), and the like. It is done.

(C) The hydrophobic monomer is used from the viewpoint of improving the printing density. Examples of the hydrophobic monomer include alkyl (meth) acrylates and aromatic group-containing monomers.
As the alkyl (meth) acrylate, those having an alkyl group having 1 to 22 carbon atoms, preferably 6 to 18 carbon atoms are preferable. For example, methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meta) ) Acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) Examples include decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, and (iso) stearyl (meth) acrylate.
In the present specification, “(iso or tertiary)” and “(iso)” mean both the case where these groups are present and the case where these groups are not present. Indicates. “(Meth) acrylate” refers to acrylate or methacrylate.

As the aromatic group-containing monomer, a vinyl monomer having an aromatic group having 6 to 22 carbon atoms, preferably 6 to 12 carbon atoms, which may have a substituent containing a hetero atom, is preferable. Examples thereof include a styrene monomer (component (c-1)) and the above-mentioned aromatic group-containing (meth) acrylate (component (c-2)). The above-mentioned thing is mentioned as a substituent containing a hetero atom.
As the styrene monomer (c-1), styrene and 2-methylstyrene are particularly preferable. The content of the component (c-1) in the component (c) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving printing density.
As the aromatic group-containing (meth) acrylate (c-2), benzyl (meth) acrylate, phenoxyethyl (meth) acrylate and the like are particularly preferable. The content of the component (c-2) in the component (c) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving the printing density. Moreover, it is also preferable to use (c-1) component and (c-2) component together.

The monomer mixture may further contain (d) a hydroxyl group-containing monomer (hereinafter sometimes referred to as “component (d)”). The component (d) has an excellent effect of improving the dispersion stability of the water-based ink. The structural unit derived from the component (d) constitutes a part of the main chain of the graft polymer.
As the component (d), for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, polyethylene glycol (n = 2 to 30, n represents the average number of added moles of oxyalkylene group. The same)) (meth) acrylate, polypropylene glycol (n = 2-30) (meth) acrylate, poly (ethylene glycol (n = 1-15) / propylene glycol (n = 1-15)) (meth) acrylate, etc. Can be mentioned. Among these, 2-hydroxyethyl (meth) acrylate, polyethylene glycol monomethacrylate, and polypropylene glycol methacrylate are preferable.

The monomer mixture may further contain (e) a monomer represented by the following formula (4) (hereinafter sometimes referred to as “(e) component”). The structural unit derived from the component (e) constitutes a part of the main chain of the graft polymer.
^{_{CH 2 = C (R 11)}} COO (R 12 O) p R 13 (4)
Wherein R ¹¹ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ¹² is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ¹³ is , A monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, p means an average added mole number, and represents a number of 1 to 60, preferably 1 to 30. )
The component (e) has an excellent effect that the printing density of the water-based ink is improved.
In the formula (4), examples of the hetero atom include a nitrogen atom, an oxygen atom, a halogen atom, and a sulfur atom.
Preferable examples of R ¹¹ include a methyl group, an ethyl group, and an (iso) propyl group.
Preferred examples of the R ¹² O group include an oxyethylene group, an oxy (iso) propylene group, an oxytetramethylene group, an oxyheptamethylene group, an oxyhexamethylene group, and a combination of two or more of these oxyalkylenes with 2 carbon atoms. -7 oxyalkylene groups.
Preferable examples of R ¹³ include aliphatic alkyl groups having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, alkyl groups having 7 to 30 carbon atoms having an aromatic ring, and 4 to 30 carbon atoms having a heterocyclic ring. Of the alkyl group.

  Specific examples of the component (e) include methoxypolyethylene glycol (1 to 30: the value of p in the formula (4); the same applies hereinafter) (meth) acrylate, methoxypolytetramethylene glycol (1 to 30) ( (Meth) acrylate, ethoxy polyethylene glycol (1-30) (meth) acrylate, octoxy polyethylene glycol (1-30) (meth) acrylate, polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether, (iso) Propoxy polyethylene glycol (1-30) (meth) acrylate, butoxypolyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Polymerization) (1 to 30, ethylene glycol therein: 1-29) (meth) acrylate. Among these, octoxypolyethylene glycol (1-30) (meth) acrylate and polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether are preferable.

Specific examples of commercially available components (d) and (e) include Shin-Nakamura Chemical Co., Ltd. polyfunctional acrylate monomer (NK ester) M-40G, 90G, 230G, and Nippon Oil & Fats Co., Ltd. BLEMMER series, PE-90, 200, 350, PME-100, 200, 400, 1000, PP-500, 800, 1000, AP-150, 400, 550, 800 , 50PEP-300, 50POEP-800C and the like.
The components (a) to (e) can be used alone or in admixture of two or more.

The content of the components (a) to (e) in the monomer mixture at the time of producing the water-insoluble vinyl polymer (content as an unneutralized amount; the same shall apply hereinafter) or (a) to (e) in the water-insoluble polymer. ) The content of the structural unit derived from the component is as follows.
The content of component (a) is preferably 1 to 50% by weight, more preferably 2 to 40% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The content of the component (b) is preferably 1 to 25% by weight, more preferably 5 from the viewpoint of dispersion stability of the polymer particles, particularly when the polymer particles contain an azo pigment or an azo pigment mixture. -20% by weight.
The content of the component (c) is preferably 5 to 98% by weight, more preferably 10 to 60% by weight, from the viewpoint of printing density.
The content of component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight, from the viewpoint of printing density.
The content of component (e) is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of dispersion stability.

The total content of [(a) component + (d) component] in the monomer mixture is preferably 6 to 60% by weight, more preferably 10 to 50% by weight, from the viewpoint of dispersion stability in water. . The total content of [component (a) + component (e)] is preferably 6 to 75% by weight, more preferably 13 to 50% by weight, from the viewpoint of dispersion stability in water. The total content of [component (a) + component (d) + component (e)] is preferably 6 to 60% by weight, more preferably 7 to 50% by weight, from the viewpoint of dispersion stability in water. .
Further, the weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.01 to 1, more preferably 0.02 to 0.67, from the viewpoint of dispersion stability. More preferably, it is 0.03-0.50.

(Production of water-insoluble polymer)
The water-insoluble polymer used in the present invention is produced by copolymerizing a monomer mixture by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable.
The solvent used in the solution polymerization method is not particularly limited, but a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and the like. Among these, methanol, ethanol, acetone, methyl ethyl ketone, or a mixed solvent of one or more of these and water is preferable.

In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), t-butyl peroxyoctate, dibenzoyl oxide, etc. Known radical polymerization initiators such as organic peroxides can be used.
The amount of the radical polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture.
In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol and thiuram disulfide may be further added.

Since the polymerization conditions of the monomer mixture vary depending on the type of radical polymerization initiator, monomer, and solvent used, it cannot be determined unconditionally. Usually, the polymerization temperature is preferably 30 to 100 ° C, more preferably 50 to 80 ° C, and the polymerization time is preferably 1 to 20 hours. The polymerization atmosphere is preferably a nitrogen gas atmosphere or an inert gas atmosphere such as argon.
After completion of the polymerization reaction, the produced polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained polymer can be purified by repeating reprecipitation or by removing unreacted monomers and the like by membrane separation, chromatographic method, extraction method and the like.

The weight average molecular weight of the water-insoluble polymer used in the present invention is preferably 5,000 to 500,000, more preferably 10,000 to 400,000, from the viewpoint of dispersion stability of the azo pigment, and 10,000 to 300. 1,000 is particularly preferred.
The weight average molecular weight of the water-insoluble polymer is measured by the method shown in the examples.

  When the water-insoluble polymer used in the present invention has (a) a salt-forming group derived from a salt-forming group-containing monomer, it is neutralized with a neutralizing agent. As the neutralizing agent, an acid or a base can be used depending on the type of the salt-forming group in the polymer. For example, hydrochloric acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid, lactic acid, succinic acid, glycolic acid, gluconic acid, glyceric acid and other acids, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methylamine, dimethylamine , Bases such as trimethylamine, ethylamine, diethylamine, trimethylamine, triethanolamine, and tributylamine.

The degree of neutralization of the salt-forming group is preferably 10 to 200%, more preferably 20 to 150%, and particularly preferably 50 to 150%.
Here, the degree of neutralization can be determined by the following formula when the salt-forming group is an anionic group.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [acid value of polymer (KOH mg / g) × polymer weight (g) / (56 × 1000)]} × 100
When the salt-forming group is a cationic group, it can be determined by the following formula.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine value of polymer (HCL mg / g) × polymer weight (g) / (36.5 × 1000)]} × 100
The acid value and amine value can be calculated from the structural unit of the polymer. Alternatively, it can also be determined by a method in which a polymer is dissolved in an appropriate solvent (for example, methyl ethyl ketone) and titrated.

[Method for producing aqueous dispersion for inkjet recording]
The manufacturing method of the water dispersion for inkjet recording of this invention has the following processes 1-3.
Step 1: A step of heat-treating a coupling reaction product obtained by coupling a diazo compound and a coupler component at 45 to 100 ° C. to obtain an azo pigment or an azo pigment mixture Step 2: Step 1 Step of dispersing the azo pigment or azo pigment mixture obtained in step 1 in an aqueous medium to obtain an aqueous dispersion of the azo pigment or azo pigment mixture Step 3: The aqueous dispersion obtained in Step 2 The process of heat-processing at 43-100 degreeC and below the heat processing temperature in the process 1

(Process 1)
In step 1, a coupling reaction product obtained by coupling reaction of a diazo compound and a coupler component is heated at 45 to 100 ° C. to obtain an azo pigment or an azo pigment mixture (hereinafter collectively referred to as “ Also referred to as “azo pigments”.

The diazo compound used for the azo pigment is a diazonium salt of an aromatic amine, and examples of the aromatic amine include m-nitro-o-anisidine, 3-nitro-4-toluidine, and p-chloro-o-. Examples thereof include nitroaniline, p-nitroaniline, o-nitroaniline, p-methoxy-o-nitroaniline and the like.
Examples of the diazo compound used in the pigment derivative include the specific examples of the azo compound represented by the above formula (1) and the patent literature described in the description of the production method thereof (for example, JP-A No. 2003-253188, And diazo compounds described in Japanese Patent No. 3055673).

  Examples of coupler components used in azo pigments and pigment derivatives include acetoacetylanilide, acetoacetyl-o-toluidide, acetoacetyl-m-xylide, acetoacetyl-o-anisidide, acetoacetyl-2,5-dimethoxy. Examples include anilide, acetoacetyl-p-anisidide, acetoacetyl-2,5-dimethoxy-4-chloroanilide, acetoacetylanilides such as acetoacetyl-o-chloroanilide, and pyrazolones.

In the step of obtaining the azo pigment mixture, the azo pigment and the pigment derivative may be obtained by a method selected from the group consisting of (a) to (c) below, for example, using the diazo compound and the coupler component, respectively. it can.
(I) A mixture of coupling reaction products obtained by coupling reaction in the same reaction vessel using the same coupler component as the coupler component of the azo pigment and the pigment derivative is heated at 45 to 100 ° C. How to get.
(B) A method obtained by separately performing a coupling reaction for obtaining an azo pigment and a pigment derivative and mixing the obtained coupling reaction products, followed by heat treatment at 45 to 100 ° C.
(C) A method in which a coupling reaction for obtaining an azo pigment and a pigment derivative is carried out separately, separately heat-treated at 45 to 100 ° C., and then mixed.
In these, (a) which can perform the coupling reaction for obtaining an azo pigment and a pigment derivative in the same reaction tank is preferable. In (b) and (c), the coupler components of the azo pigment and the pigment derivative may be the same or different. Even when the mixture of coupling reaction products is heated (for example, (A) and (B)), the coupling reaction product is heated separately (for example, (C)). However, the preferable ranges of the heating temperature and time described later are the same.

Hereinafter, the step of obtaining the azo pigment and the step of obtaining the azo pigment mixture will be described in common.
The coupling reaction can be performed by mixing a diazo compound (diazonium salt) and a coupler component at 0 to 30 ° C., more preferably at 10 to 25 ° C., by a conventional method.
In the coupling reaction, the concentrations of the diazo compound in the diazotization liquid and the coupler component in the coupler liquid during the reaction are each preferably 2 to 25% by weight.

In step 1, from the viewpoint of completing the reaction, a heat treatment for aging the coupling reaction product obtained after the coupling reaction is performed.
The coupling reaction product is preferably filtered, washed with ion-exchanged water to remove by-product salts, and heat-dried. The heat treatment in step 1 is performed before the step 2 after the coupling reaction. As long as it is a process, it may be carried out at any stage. For example, as the aging step, a heating-only step may be provided after the end of the coupling reaction, or heating may be performed before or after the filtration step or the water washing step. Moreover, you may heat by combining a maturing and drying at a drying process. The heat treatment in step 1 may be performed in two or more steps.

When both the heating in the aging step and the heating in the drying step are performed and the respective temperatures are different, the heating temperature in step 3 to be described later is based on the higher one of those temperatures, and the temperature The following. In this case, the heating time at the higher temperature is set as the heating time in step 1 described later. Moreover, when performing the heating in an aging process and a drying process at the same temperature, let the total time of both be the heating time of the process 1 mentioned later. The aging step and the drying step in step 1 are preferably controlled so as to be held at a constant temperature for a fixed time. When the temperature is not constant and the fluctuation width is less than 5 ° C., the most constant temperature in the fluctuation width can be set as the heating temperature, and the heating time at the temperature can be calculated.
In the method (c), when the azo pigment and the pigment derivative are separately heat-treated and manufactured separately after the coupling reaction, the heating in step 3 described later is performed when the heating temperatures are different. As the temperature, the lower one of the heating temperatures in step 1 is used as a reference, and the temperature is set to be equal to or lower than that temperature. In this case, the heating time in step 1 is the heating time at the lower temperature.

The heating temperature in Step 1 is 45 to 100 ° C., preferably 50 to 95 ° C., more preferably 60 to 95 ° C., from the viewpoint of heat resistance and work efficiency of the azo pigment or pigment derivative.
The heating time in step 1 is preferably 30 minutes to 48 hours, more preferably 1 hour to 24 hours, still more preferably 1 hour to 12 hours, and particularly preferably 1 hour to 6 hours. Of the heating time, the heating time in the ripening step is preferably 30 minutes or more and 6 hours or less, more preferably 30 minutes or more and 3 hours or less.
As the azo pigment obtained in step 1, a compound represented by the following formula (5) is preferable.

(Wherein R ¹ , R ² and R ⁶ each independently represents a hydrogen atom, a chlorine atom, a nitro group, a methyl group or a methoxy group, and R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom, Represents a chlorine atom, a methyl group, a methoxy group or an ethoxy group.)

(Process 2)
In step 2, the azo pigment obtained in step 1 is dispersed in an aqueous medium to obtain an aqueous dispersion such as an azo pigment.
In step 2, an azo pigment or an azo pigment mixture is dispersed in an aqueous medium with a known surfactant, water-soluble polymer, water-insoluble polymer, etc. by a conventional method to obtain an aqueous dispersion such as an azo pigment. Can be obtained.
The aqueous dispersion obtained in step 2 is preferably an aqueous dispersion of water-insoluble polymer particles containing an azo pigment or the like from the viewpoint of color developability. The method for obtaining the aqueous dispersion is not particularly limited, but the organic solvent obtained by dispersing the mixture containing the water-insoluble polymer, water, and organic solvent such as the azo pigment obtained in Step 1 is dispersed. A method of removing water and obtaining an aqueous dispersion of water-insoluble polymer particles containing an azo pigment or the like is preferable.

In this method, first, a water-insoluble polymer (hereinafter also simply referred to as “polymer”) is dissolved in an organic solvent, and then premixed azo pigments, water, and if necessary, a neutralizing agent, a surface active agent. A method of adding an agent or the like to the obtained organic solvent solution and mixing to obtain an oil-in-water dispersion is preferable. In the mixture, the azo pigment is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, the organic solvent is preferably 10 to 70% by weight, more preferably 10 to 50% by weight, and the polymer is The amount is preferably 2 to 40% by weight, more preferably 3 to 20% by weight, and water is preferably 10 to 70% by weight, more preferably 20 to 70% by weight.
When the polymer has a salt-forming group, it is preferable to use a neutralizing agent, but the degree of neutralization is not particularly limited. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5-10. The pH can also be determined by the desired degree of neutralization of the polymer. Examples of the neutralizing agent include those described above. Further, the polymer may be neutralized in advance.

  Examples of the organic solvent include alcohol solvents such as ethanol, isopropanol and isobutanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone, and ether solvents such as dibutyl ether, tetrahydrofuran and dioxane. The organic solvent has a solubility in 100 g of water of 20 ° C., preferably 5 g or more, more preferably 10 g or more, more specifically 5 to 80 g, and even more preferably 10 to 50 g. . In particular, methyl ethyl ketone and methyl isobutyl ketone are preferable.

There is no restriction | limiting in particular in the dispersion method of the mixture in the process 2. FIG. Although the average particle size of the polymer particles can be atomized only by the main dispersion until the desired particle size is reached, it is preferably pre-dispersed and then subjected to further dispersion by applying a shear stress to obtain the average particle size of the polymer particles. It is preferable to control the diameter to a desired particle diameter. 5-50 degreeC is preferable as a temperature of the dispersion | distribution slurry in a disperser, and, as for the dispersion temperature of the process 2, 10-35 degreeC is still more preferable.
When preliminarily dispersing the mixture, a commonly used mixing and stirring device such as an anchor blade can be used. Among the mixing and stirring apparatuses, Ultra Disper [Asada Steel Corporation, product name], Ebara Milder [Ebara Manufacturing Co., Ltd., product name], TK Homomixer, TK Pipeline Mixer, TK Homojetter, TK Homomic Line Flow, High-speed agitating and mixing devices such as Filmix [above, Primix Co., Ltd., trade name], Clear Mix [M Technique Co., Ltd., trade name], and KD Mill [Kinetic Dispersion Co., Ltd., trade name] are preferred.

  Examples of means for imparting shear stress of dispersion include, for example, kneading machines such as roll mills, bead mills, kneaders and extruders, high-pressure homogenizers (Izumi Food Machinery Co., Ltd., trade name), and Minilab 8.3H type (Rannie, trade name). Homovalve type high-pressure homogenizer, Microfluidizer [Microfluidics, trade name], Nanomizer [Nanomizer, trade name], Ultimateizer [Sugino Machine Co., trade name], Genus PY [Shiramizu Chemical Co., Ltd. Name], DeBEE2000 [Nippon BEE Co., Ltd., trade name] and other chamber type high-pressure homogenizers. Among these, a high-pressure homogenizer is preferable from the viewpoint of reducing the particle size of the azo pigment.

  Next, an aqueous dispersion of polymer particles containing an azo pigment or the like can be obtained from the obtained dispersion by distilling off the organic solvent by a known method to form an aqueous system. The organic solvent in the aqueous dispersion containing the obtained polymer particles is preferably substantially removed, but may remain as long as the present invention is not impaired. The amount of residual organic solvent is preferably 0.1% by weight or less, and more preferably 0.01% by weight or less. In the case of heating when distilling off the organic solvent, from the viewpoint of maintaining the weight absorbance and printing density, the liquid temperature of the dispersion is the temperature based on the heating temperature in the heat treatment after the coupling reaction in Step 1. The temperature is preferably 5 ° C. or more, more preferably 5 ° C. or more, and still more preferably 10 ° C. or more. The heating temperature for distilling off the organic solvent is preferably about 40 to 80 ° C.

The obtained aqueous dispersion of polymer particles containing an azo pigment or the like is a polymer in which the solid content of the polymer containing an azo pigment or the like is dispersed in water as a main medium. Here, the form of the polymer particles is not particularly limited as long as the particles are formed of at least an azo pigment and a polymer. For example, a particle form in which an azo pigment or the like is included in a polymer, a particle form in which an azo pigment or the like is uniformly dispersed in a polymer, or a particle form in which an azo pigment or the like is exposed on the surface of a polymer particle are included. .
“Aqueous” in an aqueous medium means that water occupies the largest proportion in the medium, and a solvent other than water may be present unless the present invention is impaired. Similarly, the water dispersion means that water occupies the largest proportion, and a solvent other than water may be present unless the present invention is impaired.

(Process 3)
In Step 3, from the viewpoint of improving dispersion stability, the aqueous dispersion such as the azo pigment obtained in Step 2 is subjected to heat treatment at 43 to 100 ° C. and below the heat treatment temperature in Step 1 above.
The temperature of the heat treatment in Step 3 is preferably 45 to 90 ° C., more preferably 50 to 80 ° C. from the viewpoint of improving dispersion stability, and is 5 ° C. or more lower than the heating temperature in Step 1. Preferably, it is more preferably 10 ° C. or lower. The time for the heat treatment in step 3 is preferably 1 hour or more and 24 hours or less, more preferably 1 hour or more and 16 hours or less, and particularly preferably 2 hours or more and 12 hours or less. The heat treatment is preferably performed by stirring the aqueous dispersion, and can be performed under pressure in a sealed container as necessary. Note that the heat treatment in step 3 is preferably controlled so as to be held at a constant temperature for a certain time.

[Aqueous dispersion for inkjet recording and water-based ink]
The aqueous ink for inkjet recording of the present invention contains an aqueous dispersion such as an azo pigment obtained in the above steps 1 to 3, and if necessary, a wetting agent, a dispersing agent, an antifoaming agent, an antifungal agent, a chelating agent, and the like. Additives can be added. There is no restriction | limiting in particular in the mixing method of these additives.
The content of each component in the water dispersion for inkjet recording and the water-based ink is as follows from the viewpoints of printing density, weight absorbance, dispersion stability, and the like.
The content of polymer particles containing an azo pigment or the like is preferably 1 to 30% by weight, more preferably 2 to 25% by weight.
The content of the azo pigment is preferably 1 to 30% by weight, more preferably 2 to 20% by weight, and particularly preferably 2 to 10% by weight.
The polymer content is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and particularly preferably 1 to 10% by weight.
The weight ratio of [polymer / azo pigment and the like] is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, and particularly preferably 20/80 to 50/50.
The average particle diameter of the polymer particles containing an azo pigment or the like in the aqueous dispersion and the aqueous ink is preferably 40 to 400 nm, more preferably 50 to 400 from the viewpoint of printing density, weight absorbance, dispersion stability, saturation, and the like. 300 nm, particularly preferably 60 to 200 nm. In addition, the measurement of the average particle diameter of the polymer particle containing an azo pigment etc. is performed by the method as described in an Example.

The viscosity (20 ° C.) at a solid content of 10% by weight of the aqueous dispersion is preferably 2 to 6 mPa · s, and more preferably 2 to 5 mPa · s, in order to obtain a good viscosity when used as a water-based ink. Further, the viscosity (20 ° C.) of the water-based ink is preferably 2 to 12 mPa · s, and more preferably 2.5 to 10 mPa · s, in order to maintain good ejection properties. The viscosity of the water dispersion and water-based ink was measured using an E-type viscometer under the conditions of a measurement temperature of 20 ° C., a measurement time of 1 minute, a rotation speed of 100 rpm, and a standard rotor (1 ° 34 ′ × R24). taking measurement.
The preferred surface tension (20 ° C.) of the aqueous dispersion and aqueous ink of the present invention is preferably 30 to 70 mN / m, more preferably 35 to 68 mN / m as the aqueous dispersion, and preferably as the aqueous ink. Is 25-50 mN / m, more preferably 27-45 mN / m. The pH of the water-based ink is preferably 4-10.

In the following production examples, preparation examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified. The weight average molecular weight of the polymer, the average particle diameter of the azo pigment or azo pigment mixture-containing polymer particles, and the method for measuring the ink viscosity are as follows.
(1) Measurement of weight average molecular weight of polymer Polystyrene was used as a standard substance by gel chromatography using N, N-dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent. Measured. Column used: Tosoh Corporation (TSK-GEL, α-M × 2), Main body: Tosoh Corporation (HLC-8120GPC), flow rate: 1 mL / min was used.

(2) Measurement of average particle diameter of polymer particles containing azo pigments, etc. Using a laser particle analysis system (ELS-8000 manufactured by Otsuka Electronics Co., Ltd.), the correlator sensitivity is 8000 to 13000 when the filter is 3%. The ink was diluted with ion-exchanged water so that the average particle diameter of the pigment-containing polymer particles in the ink was measured. The measurement conditions were a temperature of 25 ° C., an angle between the incident light and the detector of 90 °, and an integration count of 200. The refractive index of water (1.333) was input as the refractive index of the dispersion solvent.

(3) Measurement of ink viscosity Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.), using a standard rotor (1 ° 34 ′ × R24), measuring temperature 20 ° C., measuring time 1 minute, rotation speed 100 rpm Measured under conditions.

Production Example 1 (Synthesis of polymer solution)
In a reaction vessel, 20 parts of methyl ethyl ketone, 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol), and (a) methacrylic acid (Mitsubishi Gas Chemical Co., Ltd., trade name GE-110 (MAA)) 15 Parts, (b) 10 parts of styrene macromer (Toa Gosei Co., Ltd., trade name AS-6S, number average molecular weight 6,000), 30 parts of (c) 2-ethylhexyl methacrylate (Mitsubishi Rayon Co., Ltd., trade name Acryester EH) , (C) 30 parts of styrene monomer (Nippon Steel Chemical Co., Ltd., trade name styrene monomer), and (e) methoxypolyethylene glycol monomethacrylate (in the above formula (4), p is 9, R ¹¹ and R ¹³ are methyl groups, R ¹² is an ethylene group, Shin-Nakamura chemical Co., Ltd., trade name NK ester M-90G) each of the 15 parts of Put by 0% and mixed thoroughly purged with nitrogen gas to obtain a mixed solution.
On the other hand, the remaining 90% of each of the above monomers was charged into a dropping funnel, and then 0.27 part of a polymerization chain transfer agent (2-mercaptoethanol), 60 parts of methyl ethyl ketone and 2,2′-azobis (2,4- 1.2 parts of (dimethylvaleronitrile) was added and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.
Under a nitrogen atmosphere, the mixed solution in the reaction vessel was heated to 75 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped into the reaction vessel over 3 hours. After completion of the dropwise addition, the liquid temperature of the mixed solution was maintained at 75 ° C. for 2 hours, and then a solution in which 0.3 part of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 5 parts of methyl ethyl ketone was mixed. In addition to the solution, the mixture was further aged at 75 ° C. for 2 hours and at 85 ° C. for 2 hours to complete the reaction, and a polymer solution was obtained.
A portion of the resulting polymer solution was isolated by drying at 105 ° C. under reduced pressure for 2 hours and removing the solvent. The weight average molecular weight of the obtained polymer was 196,000.

Preparation Example 1 (Preparation of diazotization liquid 1-1 for synthesis of azo pigment mixture)
After adding 432 g (4.14 mol) of 35% hydrochloric acid to 959 g of ion-exchanged water and stirring for 10 minutes at room temperature, 254 g (1.51 mol) of m-nitro-o-anisidine and a compound represented by the following formula (6) 62 g (0.14 mol) was added and dispersed by stirring. Next, 822 g of ice produced from ion-exchanged water was added to this dispersion, and the dispersion was cooled. Next, a solution obtained by dissolving 119 g (1.73 mol) of sodium nitrite in 137 g of ion-exchanged water was added and stirred for 1 hour while cooling to 10 ° C. or lower, and excess nitrous acid was lost with sulfamic acid. Filtration was performed to obtain a diazotization liquid 1-1.

Preparation Example 2 (Preparation of coupler liquid 1-1 for synthesis of azo pigment mixture)
After adding 135 g (1.00 mol) of sodium acetate to 12020 g of ion-exchanged water and stirring and dissolving at room temperature for 10 minutes, 347 g (1.67 mol) of acetoacetyl-o-anisidide and 250 g of 30% aqueous sodium hydroxide solution ( 1.88 mol) was added and dissolved. Next, 149 g (1.98 mol) of 80% acetic acid was added dropwise to the solution to adjust the pH to 6, and the temperature was adjusted to 25 ° C. to prepare a coupler solution 1-1.

Preparation Example 3 (Preparation of diazotization liquid 1-2 for azo pigment synthesis)
To 878 g of ion-exchanged water, 395 g (3.79 mol) of 35% hydrochloric acid was added and stirred at room temperature for 10 minutes, and then 254 g (1.51 mol) of m-nitro-o-anisidine was added and dispersed by stirring. Next, 752 g of ice produced from ion-exchanged water was added to this dispersion, and the dispersion was cooled. Next, a solution obtained by dissolving 109 g (1.58 mol) of sodium nitrite in 125 g of ion-exchanged water was added and stirred for 1 hour while cooling to 10 ° C. or lower, and excess nitrous acid was lost with sulfamic acid. Filtration was performed to obtain a diazotization liquid 1-2.

Preparation Example 4 (Preparation of coupler liquid 1-2 for azo pigment synthesis)
After adding 123 g (0.91 mol) of sodium acetate to 10936 g of ion-exchanged water and stirring and dissolving at room temperature for 10 minutes, 315 g (1.52 mol) of acetoacetyl-o-anisidide and 227 g of 30% aqueous sodium hydroxide solution ( 1.71 mol) was added and dissolved. Next, 135 g (1.81 mol) of 80% acetic acid was added dropwise to the solution to adjust the pH to 6, and the temperature was adjusted to 25 ° C. to prepare a coupler liquid 1-2.

Preparation Example 5 (Preparation of diazotization liquid 1-3 for pigment derivative synthesis)
To 82 g of ion-exchanged water, 36.6 g (0.35 mol) of 35% hydrochloric acid was added and stirred at room temperature for 10 minutes, and then 62 g of the compound represented by the formula (6) was added and stirred to disperse. I let you. Next, 70 g of ice produced from ion-exchanged water was added to this dispersion, and the dispersion was cooled. Next, a solution obtained by dissolving 10.1 g (0.15 mol) of sodium nitrite in 12 g of ion-exchanged water was added and stirred for 1 hour while cooling to 10 ° C. or less, and excess nitrous acid was lost with sulfamic acid. Then, it filtered and it was set as the diazotization liquid 1-2.

Preparation Example 6 (Preparation of coupler liquid 1-3 for pigment derivative synthesis)
To a solution obtained by adding 11.3 g (0.08 mol) of sodium acetate to 1007 g of ion-exchanged water and stirring for 10 minutes at room temperature, 29.1 g (0.14 mol) of acetoacetyl-o-anisidide and 30% aqueous sodium hydroxide solution 20.9 (0.16 mol) was added and dissolved. Next, 12.4 g (0.17 mol) of 80% acetic acid was added dropwise to the solution to adjust the pH to 6, and the temperature was adjusted to 25 ° C. to obtain a coupler solution 1-3.

Production Example 2 (Synthesis of azo pigment mixture 1)
While stirring the coupler liquid 1-1, the diazotization liquid 1-1 was dropped at room temperature (20 ° C., the same applies hereinafter) over 120 minutes to perform a coupling reaction, and then the reaction liquid was added to 70. The temperature was raised to 0 ° C. and aged for 60 minutes. Next, filtration and washing with ion-exchanged water were performed to remove by-product salts and the like, followed by drying for 2 hours with a dryer at 70 ° C. until the weight change per hour became 1% or less. This dry pigment mixture was pulverized to obtain an azo pigment mixture 1 (642 g).

Production Example 3 (Synthesis of azo pigment mixture 2)
An azo pigment mixture 2 (646 g) was obtained in the same manner as in Production Example 2 except that the aging temperature was 80 ° C. and the drying temperature was 80 ° C.

Production Example 4 (Synthesis of azo pigment mixture 3)
An azo pigment mixture 3 (651 g) was obtained in the same manner as in Production Example 2 except that the aging temperature was 90 ° C. and the drying temperature was 90 ° C.

Production Example 5
(Synthesis of azo pigment 1)
While stirring the coupler liquid 1-2, the diazotization liquid 1-2 was dropped at room temperature over 120 minutes to perform a coupling reaction, and then the reaction liquid was heated to 70 ° C. Aged for 60 minutes. Next, filtration and washing with ion-exchanged water were performed to remove by-product salts and the like, followed by drying for 2 hours with a dryer at 70 ° C. until the weight change per hour became 1% or less. The dried pigment was pulverized to obtain azo pigment 1 (547 g).

(Synthesis of pigment derivative 1)
While stirring the coupler liquid 1-3, the diazotization liquid 1-3 was dropped at room temperature over 40 minutes to perform a coupling reaction, and then the temperature of the reaction liquid was increased to 70 ° C. Aged for 60 minutes. Next, filtration and washing with ion-exchanged water were performed to remove by-product salts and the like, followed by drying for 2 hours with a dryer at 70 ° C. until the weight change per hour became 1% or less. The dried pigment derivative was pulverized to obtain pigment derivative 1 (87 g) represented by the following formula (7).

(Production of azo pigment mixture 4)
The azo pigment 1 (431 g) and the pigment derivative 1 (69 g) were mixed in powder in a metal kettle grounded at room temperature for 10 minutes to obtain an azo pigment mixture 4.

Production Example 6
(Synthesis of azo pigment 2)
Azo pigment 2 (552 g) was obtained in the same manner as in Production Example 5 except that the aging temperature was 80 ° C. and the drying temperature was 80 ° C.
(Synthesis of pigment derivative 2)
A pigment derivative 2 (88 g) represented by the formula (7) was obtained in the same manner as in Production Example 5 except that the aging temperature was 80 ° C. and the drying temperature was 80 ° C.
(Production of azo pigment mixture 5)
An azo pigment mixture 5 was obtained in the same manner as in Production Example 5 except that the azo pigment 2 and the pigment derivative 2 were used.

Production Example 7
(Synthesis of azo pigment 3)
An azo pigment 3 (557 g) was obtained in the same manner as in Production Example 5 except that the aging temperature was 90 ° C. and the drying temperature was 90 ° C.
(Synthesis of pigment derivative 3)
The same procedure as in Production Example 5 was conducted except that the aging temperature was 90 ° C. and the drying temperature was 90 ° C., to obtain pigment derivative 3 (89 g) represented by the formula (7).
(Production of azo pigment mixture 6)
An azo pigment mixture 6 was obtained in the same manner as in Production Example 5 except that the azo pigment 3 and the pigment derivative 3 were used.

Production Example 8
(Synthesis of azo pigment 4)
Azo pigment 4 (535 g) was obtained in the same manner as in Production Example 5 except that the aging temperature was 40 ° C., the aging time was 20 minutes, and the drying temperature was 40 ° C.
(Synthesis of pigment derivative 4)
Pigment derivative 4 (85 g) represented by the formula (7) was obtained in the same manner as in Production Example 5 except that the aging temperature was 40 ° C., the aging time was 20 minutes, and the drying temperature was 40 ° C.
(Production of azo pigment mixture 7)
An azo pigment mixture 7 was obtained in the same manner as in Production Example 5 except that the azo pigment 4 and the pigment derivative 4 were used.

Example 1 (Production of aqueous dispersion of polymer particles containing azo pigment mixture)
25 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and 4.1 parts (5N sodium hydroxide aqueous solution) of 4.1 parts (neutralization degree 75%) ), And 230 parts of ion-exchanged water were added to neutralize the salt-forming groups. Then, using an ultra disper manufactured by Asada Tekko Co., Ltd., the disper blade was rotated 2000 times per minute and dispersed for 10 minutes. 75 parts of the azo pigment mixture 1 obtained in the above was added, the disperse blade was rotated 9000 per minute, and dispersion treatment was performed at 15 ° C. or lower for 1 hour.
Next, the resulting dispersion was used for 2 hours at a peripheral speed of 15 m / s using a pico mill (dispersion medium: zirconia, temperature: 20 ° C., dispersion medium / dispersion weight ratio: 8/2) manufactured by Asada Tekko Co., Ltd. Distributed processing. The obtained mixture was subjected to 10-pass dispersion treatment at a pressure of 200 MPa with a microfluidizer (trade name, manufactured by Microfluidics). Next, 250 parts of ion-exchanged water was added to the obtained dispersion and stirred, and then immersed in a 60 ° C. water bath to remove methyl ethyl ketone under reduced pressure, and a part of water was further removed to obtain a solid content concentration. An aqueous dispersion A of 20% azo pigment mixture-containing polymer particles was obtained.
Next, the obtained aqueous dispersion A was stirred and heat-treated at the temperature shown in Table 1 for 3 hours, and then a 5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, Fuji Photo Film). The aqueous dispersion of polymer particles containing an azo pigment mixture having a solid content concentration of 20% is removed by filtering with a 25 mL needleless syringe (manufactured by Terumo Corporation) with a volume of 20% solid content. Obtained.

(Manufacture of water-based ink)
35 parts of an aqueous dispersion of the azo pigment mixture-containing polymer particles, 17 parts of glycerin, 2 parts of 2-pyrrolidone, 1 part of triethanolamine, 1 part of triethylene glycol monobutyl ether, 3 parts of 1,2-hexanediol, 1 part of Knoll 465 (manufactured by Nissin Chemical Industry Co., Ltd.), 0.3 part of Proxel XL2 (manufactured by Avicia Co., Ltd.) and 39.7 parts of ion-exchanged water were mixed, and the resulting mixture was stirred for 2 hours at room temperature The liquid was filtered with a 25 mL needleless syringe equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) to remove coarse particles. Obtained.

Example 2 and Comparative Example 1
In Example 1, an azo pigment mixture having a solid content concentration of 20% was obtained in the same manner as in Example 1, except that the aqueous dispersion A of polymer particles containing azo pigment mixture was heat-treated at the temperature shown in Table 1. An aqueous dispersion of contained polymer particles was obtained. Next, a water-based ink was obtained in the same manner as in Example 1.

Examples 3-12 and Comparative Examples 2-8
In the production of the aqueous dispersion of the azo pigment mixture-containing polymer particles of Example 1, the azo pigment mixtures 2 to 7 shown in Table 1 were used in place of the azo pigment mixture 1, and the temperatures shown in Table 1 were used. An aqueous dispersion of azo pigment mixture-containing polymer particles was obtained in the same manner as in Example 1 except that the heat treatment was performed in the same manner as in Example 1. Next, a water-based ink was produced in the same manner as in Example 1.

The aqueous inks obtained in Examples 1 to 12 and Comparative Examples 1 to 8 were subjected to the following (1) measurement of weight absorbance, (2) measurement of printing density, and (3) dispersion stability test to show ink performance. Evaluated. The results are shown in Table 1.
(1) Measurement of weight absorbance Using a spectrophotometer U-3010 (manufactured by Hitachi, Ltd.), the absorbance of the diluted ink diluted 10,000 times with ion-exchanged water is measured at room temperature and appears in the range of 432 to 445 nm. Measure the peak top intensity and calculate the gravimetric absorbance as follows:
[Weight Absorbance] = [Absorbance] × [Dilution Ratio] / [Solid Concentration in Ink]
Sought according to.

(2) Measurement of printing density Using a commercially available inkjet printer (manufactured by Epson Corporation, model number: PX-V630), solid printing is performed on commercially available plain paper (high quality plain paper, manufactured by XEROX Corporation, trade name: XEROX 4024). [Printing condition = paper type: plain paper, mode setting: fast], left at 25 ° C. for 24 hours, and then measure the printing density with a Macbeth densitometer (manufactured by Gretag Macbeth, product number: RD914) at 10 locations. The average value was obtained.

(3) Dispersion stability test After placing the ink in a sealed container and storing it in a thermostatic chamber at 60 ° C for one month, using the laser particle analysis system, adjusting the temperature to 25 ° C, the correlator when the filter is 3% The ink was diluted with ion-exchanged water so as to have a sensitivity of 8000 to 13000, and the average particle diameter of the azo pigment mixture-containing polymer particles in the ink was measured.
As an indicator of dispersion stability, dispersion stability is expressed by the following formula:
Dispersion stability (%) = [[average particle diameter after storage at 60 ° C. for one month] / [average particle diameter before storage (initial average particle diameter)]] × 100
Sought according to.

  From Table 1, it can be seen that the water-based inks of Examples 1 to 12 have higher weight absorbance and printing density than those of Comparative Examples 1 to 8, and are excellent in dispersion stability.

Claims (8)

The manufacturing method of the aqueous dispersion for inkjet recording which has the following processes 1-3.
Step 1: A step of obtaining a azo pigment by heat-treating a coupling reaction product obtained by coupling a diazo compound and a coupler component at 45 to 100 ° C. Step 2: The azo obtained in Step 1 Step of dispersing an aqueous pigment in an aqueous medium to obtain an aqueous dispersion of an azo pigment Step 3: The aqueous dispersion obtained in Step 2 is at 43 to 100 ° C. and below the heat treatment temperature in Step 1 Heat treatment process The manufacturing method of the aqueous dispersion for inkjet recording which has the following processes 1-3.
Step 1: A coupling reaction product obtained by coupling reaction of a diazo compound and a coupler component is heat-treated at 45 to 100 ° C. to contain an azo pigment and an azo pigment derivative having a polar group Step of obtaining a pigment mixture Step 2: Step of dispersing the azo pigment mixture obtained in Step 1 in an aqueous medium to obtain an aqueous dispersion of the azo pigment mixture Step 3: Water dispersion obtained in Step 2 Heat-treating at a temperature of 43 to 100 ° C. and below the heat treatment temperature in step 1   The inkjet according to claim 2, wherein in step 1, the azo pigment and the azo pigment derivative having a polar group are obtained by a coupling reaction in the same reaction tank using the same coupler component. A method for producing an aqueous recording dispersion.   In step 2, after dispersing the mixture containing the azo pigment or azo pigment mixture obtained in step 1 and a water-insoluble polymer, water and an organic solvent, the organic solvent is removed, and the azo pigment is removed. Or the manufacturing method of the water dispersion for inkjet recording in any one of Claims 1-3 which obtains the water dispersion of the water-insoluble polymer particle containing an azo pigment mixture.   The process for producing an aqueous dispersion for ink jet recording according to any one of claims 1 to 4, wherein in step 1, the time for the heat treatment is from 30 minutes to 48 hours.   The method for producing an aqueous dispersion for inkjet recording according to any one of claims 1 to 5, wherein the temperature of the heat treatment in Step 3 is a temperature lower by 5 ° C or more than the heat treatment temperature in Step 1.   The method for producing an aqueous dispersion for inkjet recording according to any one of claims 1 to 6, wherein in step 3, the time for heat treatment is 1 hour or more and 24 hours or less.   An aqueous ink for ink-jet recording, comprising an aqueous dispersion of an azo pigment or an aqueous dispersion of an azo pigment mixture obtained by the production method according to claim 1.