JP4901172B2 - Method for producing pigment dispersion - Google Patents

Description

  The present invention relates to a method for producing a pigment dispersion.

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. This method is easily spread at a full color and is inexpensive, and can be used as a recording member, and can be used as a recording member.
Patent Document 1 discloses an ink containing 10 to 1000 ppm of phthalic acid diester and latex, and describes a method of adding a dialkyl phthalate and latex in the ink. There are few, and sufficient function is not demonstrated.
Patent Document 2 discloses that in an inkjet pigment ink in which pigment particles are dispersed in an aqueous medium, the total content of fatty acid derivatives in the inkjet pigment ink is 1.0% by mass or less, and the surface of the pigment particles is An ink-jet pigment ink is disclosed which is coated with a water-insoluble and water-dispersible polymer layer, and describes a method of adding a fatty acid derivative to a dispersion of pigment particles.
However, inks produced by these production methods have improved performance to some extent, but are not sufficiently stable, and there is a demand for obtaining a more stable ink.

JP 2003-183554 A JP 2003-147236 A

  An object of the present invention is to provide a method for producing a pigment dispersion capable of allowing a water-insoluble organic compound to be stably present in polymer particles.

The inventors of the present invention have a method for producing a pigment dispersion having the following steps (I) and (III), and a method for producing a water-based ink for inkjet recording, which comprises a step of producing a pigment dispersion using the production method. I will provide a.
Step (I): a step of mixing a water-insoluble polymer (A), a water-insoluble organic compound (B), an organic solvent (C) and water to obtain a mixture containing them ,
The water-insoluble polymer (A) is (a) a salt-forming group-containing monomer, (b) a macromer, (c) a hydrophobic monomer, (d) a hydroxyl group-containing monomer, and (e) a monomer represented by the following formula (1) Each of which is produced by copolymerizing two or more monomer mixtures alone, having a weight average molecular weight of 5,000 to 500,000, dried at 105 ° C. for 2 hours, and then dissolved in 100 g of water at 25 ° C. The amount of dissolution when it is made to be 10 g or less,
_{^{CH 2 = C (R 1)}} COO (R 2 O) p R 3 (1)
Wherein R ¹ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ² is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ³ is A monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, p means an average number of added moles, and represents a number of 1 to 60.)
The water-insoluble organic compound (B) has two or more ester or ether bonds in the molecule, carboxylic acid ester, phosphate ester or ether compound, or one or more ester or ether bonds in the molecule, A carboxylic acid ester, a phosphoric acid ester or an ether compound having at least one functional group selected from the group consisting of carboxylic acid, phosphoric acid residue, carbonyl group, epoxy group and hydroxyl group, and having a molecular weight of 100 to The amount dissolved at 2,000 and 100 g of water (20 ° C.) is 5 g or less .
Step (III): A step of mixing the mixture and the pigment (D) and then dispersing to obtain a pigment dispersion.

  In the pigment dispersion obtained by the method for producing a pigment dispersion of the present invention, a water-insoluble organic compound can be stably present in polymer particles.

[Method for producing pigment dispersion]
The present invention is a method for producing a pigment dispersion having the following steps (I) and (III).
Step (I): A step of obtaining a mixture containing a water-insoluble polymer (A), a water-insoluble organic compound (B), an organic solvent (C) and water.
Step (III): A step of mixing the mixture and the pigment (D) and then dispersing to obtain a pigment dispersion.

[Production Method of Pigment Dispersion: Step (I)]
Step (I) is a step of obtaining a mixture containing a water-insoluble polymer (A), a water-insoluble organic compound (B), an organic solvent (C) and water. Specifically, the water-insoluble polymer (A) and the water-insoluble organic compound (B) are dissolved in the organic solvent (C), and then water and, if necessary, a neutralizing agent, a surfactant, It is preferable to add to the obtained organic solvent solution and mix to obtain an oil-in-water dispersion. The resulting dispersion is a dispersion of water-insoluble polymer particles containing a water-insoluble organic compound (hereinafter also referred to as a water-insoluble organic compound-containing polymer emulsion).
The water-insoluble polymer (A) and the water-insoluble organic compound (B) are directly contacted and mixed to increase the affinity between the water-insoluble polymer (A) and the water-insoluble organic compound (B), thereby dispersing the pigment. During the treatment, the water-insoluble organic compound (B) is separated from the polymer particles derived from the water-insoluble polymer (A) to form oil droplets, so-called oil floating is suppressed, and the water-insoluble organic compound (B) is contained in the polymer particles. It can exist stably.
In the mixture obtained as described above, from the viewpoint of dispersion stability and image clarity, the water-insoluble polymer (A) is preferably 2 to 30% by weight, more preferably 3 to 20% by weight, and the water-insoluble organic compound (B). ) Is preferably 1 to 30% by weight, more preferably 1 to 20% by weight. The organic solvent (C) is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, and the water is preferably 10 to 70% by weight, more preferably 20 to 70% by weight.
When the water-insoluble polymer (A) 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 finally obtained pigment dispersion has neutral liquidity, for example, pH of 4.5 to 10. The pH can also be determined by the desired degree of neutralization of the water-insoluble polymer. Examples of the neutralizing agent include those described above. A water-insoluble polymer previously neutralized may be mixed. The mixing temperature is preferably about 5 to 50 ° C. from the viewpoint of the boiling point of the organic solvent to be used.

[Production Method of Pigment Dispersion: Step (III)]
Step (III) is a step of obtaining a pigment dispersion by mixing the mixture obtained in step (I), and optionally step (II) described later, and pigment (D), and then dispersing the mixture. In addition, you may add an organic solvent and water further to the mixture obtained by process (I) or (II) from a viewpoint of particle diameter reduction of a pigment. In the step (III), the content of the organic solvent in the mixture is preferably 35% by weight or less, and more preferably from the viewpoint of reducing floating of the water-insoluble organic compound (B) in the ink when the aqueous ink is used. Is preferably removed until it becomes 25% by weight or less, particularly preferably 20% by weight or less, and depending on the type of pigment, it may be 5% by weight or more from the viewpoint of reducing the particle size during dispersion. The content of the organic solvent in the mixture may be adjusted by the amount of the organic solvent used in the step (I) or may be adjusted by the step (II) described later.
The resulting pigment dispersion is a dispersion of water-insoluble polymer particles containing a pigment and a water-insoluble organic compound.
The mixing ratio of the pigment in the step (III) is preferably 80 to 900 parts by weight, and more preferably 100 to 400 parts by weight with respect to 100 parts by weight of the water-insoluble polymer, from the viewpoints of dispersion stability and image clarity.
In the pigment dispersion obtained in step (III), the pigment content is preferably 1 to 40% by weight, more preferably 5 to 30% by weight, from the viewpoint of dispersion stability.
There is no restriction | limiting in particular in the dispersion method of the mixture in process (III). 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. Thereby, a uniform dispersion of water-insoluble polymer particles containing a pigment can be obtained. The dispersion in the step (III) is preferably 5 to 50 ° C., more preferably 10 to 35 ° C., from the viewpoint of reducing the particle size of the pigment dispersion.

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 devices, 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 [Special Machine Industry Co., Ltd., trade name], Clear Mix [M Technique Co., Ltd., trade name], KD Mill [Kinetic Dispersion Co., Ltd., trade name] and the like are preferable.
Examples of means for imparting the shear stress of this dispersion include, for example, a kneader such as a roll mill, a bead mill, a kneader, and an extruder, a high-pressure homogenizer [Izumi Food Machinery Co., Ltd., trade name], Minilab 8.3H type (Rannie Co., trade name). Homovalve type high pressure homogenizers, microfluidizers (Microfluidics, trade name), Nanomizers (Nanomizer Co., trade names), Ultimateizers (Sugino Machine Co., trade names), Genus PY (Shiramizu Chemical Co., Ltd.) , Product name], DeBEE2000 [Nippon BEE Co., Ltd., product name] and the like, chamber type high pressure homogenizers and the like. Among these, when a pigment is used, a high-pressure homogenizer is preferable from the viewpoint of reducing the particle size of the pigment.

Step (III) preferably has a step of removing the organic solvent after the dispersion treatment. After the dispersion treatment, the organic solvent is distilled off by a known method to form an aqueous system, which is preferable for use as an aqueous ink.
The removal of the organic solvent can be performed by a known method such as distillation. The organic solvent in the pigment dispersion containing the obtained pigment and the water-insoluble organic compound is substantially removed, and the amount of the organic solvent is usually 0.1% by weight or less, preferably 0.01% by weight or less. .
A dispersion of water-insoluble polymer particles containing a pigment and a water-insoluble organic compound is a dispersion of water-insoluble polymer particles containing a pigment and a water-insoluble organic compound dispersed in water as a main solvent. It is. Here, the form of the water-insoluble polymer particles is not particularly limited, as long as the particles are formed of at least a pigment, a water-insoluble organic compound, and a water-insoluble polymer. For example, a particle form in which a pigment and a water-insoluble organic compound are encapsulated in a water-insoluble polymer, a particle form in which a pigment and a water-insoluble organic compound are uniformly dispersed in a water-insoluble polymer, and a water-insoluble containing a water-insoluble organic compound A particle form in which a pigment is exposed on the surface of polymer particles is included. In the pigment dispersion and in the water-based ink, the water-insoluble organic compound is present without substantially forming oil droplets on the ink surface layer. This is considered to be because the water-insoluble organic compound is stably taken into the water-insoluble polymer particles and the interaction with the pigment is involved in the production method of the present invention.
The average particle diameter of the water-insoluble polymer particles containing the obtained pigment and the water-insoluble organic compound is preferably from 0.01 to 0.5 μm, more preferably from the viewpoint of preventing clogging of the printer nozzle and dispersion stability. It is 0.03-0.3 micrometer, Most preferably, it is 0.05-0.2 micrometer. The average particle diameter can be measured with a laser particle analysis system ELS-8000 (cumulant analysis) manufactured by Otsuka Electronics Co., Ltd. The measurement conditions are a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and an integration count of 100. The refractive index of water (1.333) is input as the refractive index of the dispersion solvent. The measurement concentration is about 5 × 10 ⁻³ wt%.

[Production Method of Pigment Dispersion: Step (II)]
Step (II) is a step in which at least a part of the organic solvent (C) is removed from the mixture obtained in step (I) to obtain a mixture from which the organic solvent has been removed. In step (II), the content of the organic solvent in the mixture in step (III) is preferably adjusted to 35% by weight or less, whereby the formation of organic solvent droplets of the water-insoluble organic compound (B) at the time of pigment dispersion. The purpose is to reduce the floating of the water-insoluble organic compound (B) in the ink when the water-based ink is used. The removal of the organic solvent (C) can be performed by a known method such as distillation.
The content of the organic solvent in the mixture obtained in step (II) is preferably 35% by weight or less, more preferably from the viewpoint of reducing floating of the water-insoluble organic compound (B) in the ink when it is used as a water-based ink. Is preferably removed until it becomes 25% by weight or less, particularly preferably 20% by weight or less, and depending on the type of pigment, it may be 5% by weight or more from the viewpoint of reducing the particle size during dispersion.

[Compounds used in the production method]
Hereinafter, the compounds used in the present invention will be described.

[Compound used in production method: water-insoluble polymer (A)]
A 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 the polymer is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C. Say. When the polymer has a salt-forming group, the dissolution amount is a dissolution amount when the salt-forming group of the polymer is neutralized 100% with acetic acid or sodium hydroxide depending on the type.
Such water-insoluble polymers 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”), (c ) A hydrophobic monomer (hereinafter sometimes referred to as “component (c)”), (d) a hydroxyl group-containing monomer (hereinafter sometimes referred to as “component (d)”), and (e) represented by the following formula (1). Monomers (hereinafter sometimes referred to as “component (e)”) are each obtained alone or in combination of two or more.
^{_{CH 2 = C (R 1)}} COO (R 2 O) p R 3 (1)
Wherein R ¹ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ² is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ³ 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. )
From the viewpoint of dispersion stability, a water-insoluble vinyl polymer obtained by addition polymerization of a vinyl monomer (vinyl compound, vinylidene compound, vinylene compound) is preferable.
Examples of the water-insoluble polymer include a water-insoluble vinyl polymer obtained by copolymerizing a monomer mixture (hereinafter also referred to as “monomer mixture”) containing the component (a) and the component (b) and / or the component (c). preferable. This water-insoluble polymer has a structural unit derived from the component (a), a structural unit derived from the component (b) and / or a structural unit derived from the component (c).

[Water-insoluble polymer (A): component (a)]
(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.
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, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of dispersion stability and ejection stability.

[Water-insoluble polymer (A): component (b)]
(B) The macromer is used from the viewpoint of enhancing the dispersion stability of the polymer particles, particularly when the polymer particles contain a colorant. 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 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 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. As an aromatic group-containing (meth) acrylate, an arylalkyl having 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably 7 to 12 carbon atoms, which may have a substituent containing a hetero atom. (Meth) acrylate having an aryl group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a group or a substituent containing a hetero atom 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 in the styrene macromer or the aromatic group-containing (meth) acrylate in the aromatic group-containing (meth) acrylate macromer is preferably 50% by weight from the viewpoint of increasing the affinity with the pigment. Above, more preferably 70% by weight or more.
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.

[Water-insoluble polymer (A): component (c)]
(C) The hydrophobic monomer is used from the viewpoint of improving printing density, glossiness, and image clarity. 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.

The aromatic group-containing monomer has an aromatic group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a substituent containing a hetero atom. Vinyl monomers are preferable, and examples thereof include the styrene monomer (c-1 component) and the aromatic group-containing (meth) acrylate (c-2 component). The above-mentioned thing is mentioned as a substituent containing a hetero atom.
Among the components (c), styrenic monomers (component c-1) are preferred from the viewpoint of improving glossiness and printing density. Examples of the styrenic monomers include those described above, and particularly styrene and 2-methylstyrene. 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 and glossiness.

  In addition, examples of the aromatic group-containing (meth) acrylate (c-2) component include those described above, and benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and the like are 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 glossiness. Moreover, it is also preferable to use (c-1) component and (c-2) component together.

[Water-insoluble polymer (A): component (d)]
The monomer mixture may further contain (d) a hydroxyl group-containing monomer (hereinafter sometimes referred to as “component (d)”). (D) The hydroxyl group-containing monomer exhibits an excellent effect of enhancing dispersion stability.
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.

[Water-insoluble polymer (A): component (e)]
The monomer mixture may further contain (e) a monomer represented by the following formula (1) (hereinafter sometimes referred to as “(e) component”).
^{_{CH 2 = C (R 1)}} COO (R 2 O) p R 3 (1)
Wherein R ¹ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ² is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ³ 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) exhibits an excellent effect of improving the printing density, glossiness, and image clarity of the ink.
In the formula (1), examples of the hetero atom include a nitrogen atom, an oxygen atom, a halogen atom, and a sulfur atom.
Preferable examples of R ¹ include methyl group, ethyl group, (iso) propyl group and the like.
Preferred examples of the R ² 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 ³ 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 (11), 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, butoxy polyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Copolymerization) (1-30, 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 (d) and (e) components 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-800B, and the like.

The content of the components (a) to (e) in the monomer mixture at the time of production of the water-insoluble polymer (A) (content as an unneutralized amount; the same applies hereinafter) or the water-insoluble polymer (A) (a The content of the structural unit derived from the components (e) to (e) is as follows.
The content of component (a) is preferably 1 to 50% by weight, more preferably 2 to 40% by weight, and particularly preferably 3 to 20% 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 to 20% by weight, particularly from the viewpoint of enhancing the interaction of the pigment (D).
The content of the component (c) is preferably 5 to 98% by weight, more preferably 10 to 60% by weight, and particularly preferably 20 to 60% by weight from the viewpoints of glossiness and image clarity.
The content of component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
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 of the resulting dispersion.
The total content of [component (a) + component (d)] in the monomer mixture is preferably 6 to 60% by weight, more preferably 10 to 50% by weight, from the viewpoint of dispersion stability of the resulting dispersion. is there. 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 of the resulting dispersion. Further, the total content of [(a) component + (d) component + (e) component] is preferably 6 to 60% by weight, more preferably 7 to 50% from the viewpoint of dispersion stability of the resulting dispersion. % By weight.
Further, the weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.01 to 1, more preferably 0.02 to 0 from the viewpoints of glossiness and image clarity. .67, more preferably 0.03 to 0.50.

[Production of water-insoluble polymer (A)]
The water-insoluble polymer (A) 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 (A) used in the present invention is preferably 5,000 to 500,000, preferably 10,000 to 400,000, from the viewpoints of dispersion stability, water resistance and dischargeability of the pigment (D). 000 is more preferable, and 10,000 to 300,000 is particularly preferable.
The weight average molecular weight of the polymer is measured by gel chromatography using 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide-containing dimethylformamide as a solvent using polystyrene as a standard substance.

  When the water-insoluble polymer (A) used in the present invention has (a) a salt-forming group derived from a salt-forming group-containing monomer, it is used after being 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.
Degree of neutralization = {[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.
Degree of neutralization = {[weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine number 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.

[Water-insoluble organic compound (B)]
The water-insoluble organic compound (B) used in the present invention is contained in water-insoluble polymer particles and used to improve the flexibility. The water-insoluble organic compound (B) improves the flexibility of the water-insoluble polymer particles, so that the water-insoluble polymer particles discharged from the nozzles of the ink jet recording apparatus are fused to each other. It is considered that the image clarity of the printed matter is improved by uniformly diffusing and smoothing the printing surface.
The water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, more preferably a molecular weight of 100 to 1,000, from the viewpoint of improving the glossiness and image clarity of the ink.
The amount of water-insoluble organic compound dissolved in 100 g of water (20 ° C.) is 5 g or less, preferably 3 g or less, more preferably 1 g or less.

In order to improve the flexibility of the polymer, the water-insoluble organic compound (B) preferably has a LogP value of −1 to 11, more preferably 1 to 9, still more preferably 1.5 to 8, 7 is particularly preferred.
In addition, from the viewpoint of the interaction between the water-insoluble organic compound and the polymer particles, the value of [[Log P value of the water-insoluble organic compound (B)] − [Log P value of the water-insoluble polymer (A)]) is −4 to It is preferably 8, more preferably -2 to 6, still more preferably -1.5 to 5, and particularly preferably -1 to 4.
Here, “Log P value” means the logarithmic value of the 1-octanol / water partition coefficient of water-insoluble organic compounds, calculated by the fragment approach by SRC's LOGKOW / KOWWIN Program of KowWin (Syracuse Research Corporation, USA). The KowWin Program methodology is described in the following journal article: Meylan, WM and PH Howard. 1995. Atom / fragment contribution method for using octanol-water partition coefficients. J. Pharm. Sci. .). The fragment approach is based on the chemical structure of the compound and takes into account the number of atoms and the type of chemical bond. The LogP value is a numerical value generally used for relative evaluation of the hydrophilicity / hydrophobicity of an organic compound.
The Log P value of the polymer can be determined according to the following procedure.
1. The LogP value of each monomer from which each structural unit constituting the polymer is derived is determined by the SRC's LOGKOW / KOWWIN Program. In addition, the polymer structure derived from a chain transfer agent and an initiator is excluded.
2. The Log P value of each monomer is multiplied by the molar ratio (M) of the structural unit derived from that monomer in the polymer chain to determine (Log P × M) of each monomer.
3. The LogP value of the polymer is calculated by adding all (LogP × M) of each monomer obtained in 2 above.
The salt-forming group-containing monomer is calculated based on the LogP value of the monomer before neutralization.

The water-insoluble organic compound is preferably an ester, an ether, or an acid amide so that the water-insoluble organic compound can be easily contained in the polymer particles. The carboxylic acid ester, the phosphate ester, or the ester having two or more esters or ether bonds in the molecule 1 or more functional groups selected from the group consisting of one or more ester or ether bonds and carboxylic acid, phosphoric acid residue, carbonyl group, epoxy group and hydroxyl group in the ether compound (f) or molecule A carboxylic acid ester, a phosphoric acid ester or an ether compound (g) having at least one is more preferable.
(F) The number of ester or ether bonds of the compound is preferably 2 to 3. (G) As for the ester or ether bond of a compound, 1-3 are preferable. The number of functional groups is preferably 1 to 3.
Among these, an ester obtained from a monovalent carboxylic acid or a salt thereof and a polyhydric alcohol, an ester obtained from a polyvalent acid (polycarboxylic acid, phosphoric acid) or a salt thereof and a monohydric alcohol, or a polyhydric alcohol Ether compounds are preferred, and it is more preferred to have two aliphatic or aromatic carboxylic acid ester groups or three phosphoric acid ester groups. Examples of the salt include alkali metal salts, alkanolamine salts, ammonium salts and the like.

As the monovalent carboxylic acid, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, Linear aliphatic carboxylic acids such as palmitic acid, branched aliphatic carboxylic acids such as pivalic acid, unsaturated aliphatic carboxylic acids such as acrylic acid and methacrylic acid), and aromatic carboxylic acids having 6 to 12 carbon atoms (for example, As the polyvalent carboxylic acid, an aliphatic carboxylic acid having 2 to 12 carbon atoms such as maleic acid, fumaric acid, itaconic acid, succinic acid, adipic acid, and sebacic acid; phthalic acid, trimellitic acid C6-C12 aromatic carboxylic acid, phosphoric acid, etc., such as an acid, are mentioned.
The monohydric alcohol is a linear or branched aliphatic alcohol having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, ethyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol). , Aromatic alcohols having 6 to 12 carbon atoms (for example, phenol), and polyhydric alcohols having 2 to 12 carbon atoms such as ethylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and glycerin. A polyhydric alcohol is mentioned. A saturated or unsaturated fatty acid or alcohol can be used.

Specific examples of the water-insoluble organic compound include (1) aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, (3) phosphoric acid ester, (4) cycloalkane (ken) carboxylic acid ester, (5) Oxyacid ester, (6) glycol ester, (7) epoxy ester, (8) sulfonamide, (9) polyester, (10) glyceryl alkyl ether, (11) glyceryl alkyl ester, (12) glycol alkyl ether, ( 13) glycol alkyl ester, (14) ether or ester of trimethylolpropane, (15) ether or ester of pentaerythritol, and the like.
Among these, from the viewpoints of image clarity and gloss, the compounds of (1) to (3), (5), (8) and (10) are preferred, and (1) aliphatic carboxylic acid ester, (2 It is preferably at least one member selected from the group consisting of (a) aromatic carboxylic acid esters and (3) phosphoric acid esters, and (1) aliphatic carboxylic acid esters and / or (2) aromatic carboxylic acid esters. Most preferred.

  (1) The aliphatic carboxylic acid ester is preferably an aliphatic di- or tricarboxylic acid ester from the viewpoint of image clarity. The aliphatic dicarboxylic acid ester is preferably a compound represented by the following formula (2).

(In formula (2), R ⁴ and R ⁵ are each a hydrogen atom, a linear, branched or cyclic hydrocarbon group having 1 to 18 carbon atoms, an aralkyl group having 7 to 22 carbon atoms, or 6 to 22 carbon atoms. R ⁴ and a glycol ether group having 2 to 10 carbon atoms, R ⁴ and R ⁵ may be the same or different, and R ⁶ may have an unsaturated group having 1 to 18 carbon atoms. A divalent aliphatic hydrocarbon group, R ^{4 to} R ⁵ may have a substituent, n represents an average addition mole number of 0 to 20, and AO represents an alkyleneoxy group.

R ⁴ and R ⁵ are preferably a linear or branched alkyl group or alkenyl group having 2 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, from the viewpoint of improving glossiness and image clarity of printed matter. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, 2-ethylhexyl group, octyl group, dodecyl group, cetyl group and the like. The same applies to the following equations.
R ⁶ is preferably an alkylene group or an alkenylene group, and specifically includes an ethylene group, a propylene group, a trimethylene grave, a butylene group, a hexylene group, a 2-ethylhexylene group, an octylene group, a dodecylene group, and the like. Is an alkylene group having 2 to 15 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms. The same applies to the following equations.
n is preferably 0 to 15, more preferably 0 to 12, and particularly preferably 2 to 10.
AO is a C2-C4 ethyleneoxy group (EO), a propyleneoxy group (PO), or a butyleneoxy group (BO), and when n is 2 or more, they may be the same or different. AO may be added in blocks or randomly.
Examples of the substituent include halogen atoms such as fluorine, chlorine and bromine atoms, alkyl groups having 1 to 12 carbon atoms such as methyl, ethyl, propyl, isopropyl, isobutyl, t-butyl, hexyl and lauryl, cyclohexyl groups and the like. Cycloalkyl groups, aryl groups such as phenyl groups, alkoxy groups having 1 to 12 carbon atoms such as methoxy, ethoxy and isopropoxy groups, aryloxy groups such as phenyloxy groups, alkoxycarbonyl groups such as methoxycarbonyl groups, acetyl, Examples include acyl groups such as benzoyl groups, acyloxy groups such as acetyloxy groups, cyano groups, nitro groups, hydroxyl groups, carboxyl groups, oxo groups, epoxy groups, ether groups, and ester groups. These substituents may be one or a combination of two or more.

(1) Specific examples of the aliphatic dicarboxylic acid ester include dimethyl adipate, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis (butyldiethylene glycol) adipate, dimethyl sebacate And aliphatic dibasic acid esters such as diethyl sebacate, dibutyl sebacate, bis (2-ethylhexyl) sebacate, diethyl succinate and bis (2-ethylhexyl) azelate. Among these, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (butyldiethylene glycol) adipate, bis (octoxypolyethylene glycol) adipate (R ⁴ and R ⁵ are both 2-ethylhexyl, AO = EO, average added mole number n = 4, 6 or 8), diesters of aliphatic dibasic acids having 6 to 10 carbon atoms such as diethyl sebacate, dibutyl sebacate and diisobutyl sebacate are particularly preferred. Examples of the aliphatic tricarboxylic acid ester include an ester of citric acid.

  (2) The aromatic carboxylic acid ester is preferably a compound represented by the following formula (3).

(In formula (3), R ⁴ and R ⁵ are the same as above. R ⁴ and R ⁵ may be the same or different.)

  (2) Specific examples of aromatic carboxylic acid esters include dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, bis (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisodecyl phthalate, butyl benzyl Phthalic acid such as phthalate, octyl benzyl phthalate, nonyl benzyl phthalate, stearyl benzyl phthalate, octyl decyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, bis (dimethylcyclohexyl) phthalate, bis (t-butylcyclohexyl) phthalate, ethyl phthalyl ethyl glycolate Trimellitic acid such as ester, dibutyl trimellitate, diisobutyl trimellitate, tris (2-ethylhexyl) trimellitate Ester, and the like. Among these, phthalic acid diester having an aliphatic alcohol residue having 1 to 5 carbon atoms such as dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, etc., carbon number 3 such as octyl benzyl phthalate, stearyl benzyl phthalate Particularly preferred are benzyl phthalate having an alkyl group of -18, and trimellitic acid diester having an aliphatic alcohol residue of 3 to 5 carbon atoms such as dibutyl trimellitate and diisobutyl trimellitate. The aromatic carboxylic acid ester is preferably an aromatic di- or tricarboxylic acid ester.

  (3) The phosphate ester is preferably a compound represented by the following formula (4).

(In formula (4), R ⁴ and R ⁵ are the same as above. R ⁴ and R ⁵ may be the same or different.)

  (3) Specific examples of phosphoric acid esters include tributyl phosphate, tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2 -Ethylhexyl diphenyl phosphate and the like. Among these, phosphate esters having a C5-C9 alkoxyalkyl group such as tris (butoxyethyl) phosphate, phosphate esters having a C4-12 aliphatic hydrocarbon group such as tributyl phosphate, tris ( Butoxyethyl) phosphates, tricresyl phosphates, trixylenyl phosphates, cresyl diphenyl phosphates, and other phosphate esters having an aromatic hydrocarbon group of 7 to 12 carbon atoms are particularly preferred. The phosphoric acid ester is preferably a phosphoric acid di- or triester.

  (4) The cycloalkane (ken) carboxylic acid ester includes a cyclic hydrocarbon group having 3 to 8 carbon atoms, which may have one unsaturated group, and is represented by the following formula (5). Cyclohexane (cene) dicarboxylic acid ester is preferred.

(In formula (5), R ⁴ and R ⁵ are the same as described above. R ⁴ and R ⁵ may be the same or different.)
(4) Specific examples of cycloalkane (ken) dicarboxylic acid esters include cyclohexane esters such as 1,2-cyclohexanedicarboxylic acid dibutyl ester, 1,2-cyclohexanedicarboxylic acid diisononyl ester, and dibutyl 3,4-cyclohexene dicarboxylate. Examples include esters and cyclohexene esters such as 3,4-cyclohexenecarboxylic acid diisononyl ester.

  (5) The oxyacid ester is preferably a compound represented by the following formula (6).

(In formula (6), R ⁴ , R ⁵ and R ⁶ are the same as described above. R ⁴ and R ⁵ may be the same or different.)
(5) Specific examples of oxyacid esters include triethyl acetylcitrate, tributyl acetylcitrate, and methyl acetylricinoleate.

  (6) The glycol ester is preferably a compound represented by the following formula (7).

(In formula (7), R ⁴ , R ⁵ and R ⁶ are the same as described above. R ⁴ and R ⁵ may be the same or different.)
(6) Specific examples of glycol esters include diethylene glycol dibenzoate, triethylene glycol di (2-ethylhexoate), and the like.

  (7) The epoxy ester is preferably a compound represented by the following formula (8).

(In Formula (8), R ⁴ is the same as described above. R ⁷ and R ⁸ are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and R ⁹ is an alkylene group having 1 to 6 carbon atoms. Show.)
(7) Specific examples of the epoxy ester include butyl epoxy stearate and octyl epoxy stearate.

  (8) The sulfonamide is preferably a compound represented by the following formula (9).

(In Formula (9), R ⁴ and R ⁵ are the same as described above. R ⁴ and R ⁵ may be the same or different.)
(8) Specific examples of the sulfonamide include o- and p-toluenesulfonamide, N-butylbenzenesulfonamide and the like.

  (9) The polyester is preferably a compound represented by the following formula (10).

(In the formula (10), R ⁴ , R ⁵ and R ⁶ are the same as above. R ⁴ and R ⁵ and each R ⁶ may be the same or different. M is 1 to 18, preferably 1 to 1. Represents the number 10)
(9) Specific examples of polyester include poly (1,2-butanediol adipate), poly (1,3-butanediol adipate) and the like.
(10) Specific examples of the glyceryl alkyl ether include glyceryl monoether, glyceryl diether, and glyceryl triether. In these, the glyceryl monoether which has a C8-C30 linear or branched alkyl group is preferable. The alkyl group has 8 to 30 carbon atoms, preferably 8 to 22 carbon atoms, and more preferably 8 to 14 carbon atoms.
Examples of the alkyl group include 2-ethylhexyl, (iso) octyl, (iso) decyl, (iso) dodecyl, (iso) myristyl, (iso) cetyl, (iso) stearyl, and (iso) behenyl groups.
There is no restriction | limiting in particular about the position of an alkyl group, Either 1-alkyl glyceryl monoether and 2-alkyl glyceryl monoether may be sufficient.
(11) Specific examples of the glyceryl alkyl ester include glyceryl monoalkyl ester, glyceryl dialkyl ester, and glyceryl trialkyl ester.
Among these, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, palmitic acid) Linear aliphatic carboxylic acids such as branched aliphatic carboxylic acids such as pivalic acid) esters are preferred. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
More specifically, glyceryl triacetate, glyceryl diacetate, glyceryl monoacetate and the like can be mentioned.
(12) Specific examples of glycol alkyl ether include glycol monoalkyl ether and glycol dialkyl ether.
(13) Specific examples of glycol alkyl esters include glycol monoalkyl esters and glycol dialkyl esters.
Examples of the glycols (12) and (13) include ethylene glycol and neopentyl glycol, and examples of the alkyl group include linear or branched alkyl groups having 1 to 22 carbon atoms. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
Said water-insoluble organic compound (1)-(15) can be used individually or in mixture of 2 or more types.

[Organic solvent (C)]
Examples of the organic solvent (C) include alcohol solvents such as ethanol, isopropanol and isobutanol, ketone solvents such as acetone, methyl ethyl ketone and diethyl ketone, and ether solvents such as dibutyl ether, tetrahydrofuran and dioxane, and alcohol solvents. It is preferable to use one or more selected from the group consisting of ketone solvents and ether solvents. From the viewpoint of reducing the particle size of the resulting pigment dispersion, the amount of organic solvent dissolved in water (dissolved amount in 100 g of water) is preferably 10 g or more, more preferably 10 to 70 g, more preferably 10 in water at 20 ° C. ~ 50g. Further, from the viewpoint of organic solvent removability, the boiling point (1 atm) is preferably 150 ° C. or lower, more preferably 140 ° C. or lower, and the lower limit is 40 ° C. or higher from the viewpoint of stable production. Is preferable, and 50 degreeC or more is still more preferable. As such an organic solvent, methyl ethyl ketone is particularly preferable.

[Pigment (D)]
When the pigment (D) is used in a water-based ink, it is preferable to contain the pigment in the water-insoluble polymer particles from the viewpoint of bleeding resistance and water resistance.
The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments.
Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Of these, carbon black is preferred particularly for black aqueous inks. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.
Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthoraquinone pigments, and quinophthalone pigments.
Specific examples of preferred organic pigments include C.I. I. Pigment yellow, C.I. I. Pigment Red, C.I. I. Pigment violet, C.I. I. Pigment blue, C.I. I. Examples of each product are pigment and green.
Examples of extender pigments include silica, calcium carbonate, and talc.
The above pigments can be used alone or in admixture of two or more at any ratio.

[Pigment dispersion and water-based ink for inkjet recording]
The pigment dispersion obtained in the present invention can be suitably used as a pigment dispersion for inkjet recording.
The pigment dispersion obtained in the present invention may be used as an aqueous ink as it is, but a wetting agent, a penetrating agent, a dispersing agent, a viscosity modifier, an antifoaming agent, an antifungal agent, which are usually used in an aqueous ink for inkjet recording, A rust inhibitor or the like may be added.
The content of each component and the ratio thereof in the pigment dispersion or ink-jet recording aqueous ink obtained in the present invention are as follows.
The content of the water-insoluble polymer (A) is preferably from 0.5 to 30% by weight, more preferably from 1 to 20% by weight, particularly preferably from 1 to 15% by weight, from the viewpoints of printing density, image clarity and gloss. .
The content of the water-insoluble organic compound (B) is preferably from 0.11 to 10% by weight, more preferably from 0.15 to 5% by weight, and from 0.2 to 3% by weight from the viewpoint of improving image clarity and gloss. % Is particularly preferred.
The content of the pigment (D) is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, and particularly preferably 2 to 20% by weight from the viewpoint of printing density.
The weight ratio of [water-insoluble organic compound (B) / water-insoluble polymer (A)] is preferably 1/100 to 5/1, more preferably 1/50 to 2/1, from the viewpoint of improving image clarity. 1/50 to 1/1 is more preferable, 1/30 to 1/1 is particularly preferable, and 1/10 to 1/1 is most preferable.
The weight ratio of [water-insoluble organic compound (B) / pigment (D)] is preferably 1/40 to 5/1, and preferably 1/30 to 1/1 from the viewpoint of improving image clarity. Is more preferable.
The weight ratio of [water-insoluble polymer (A) / pigment (D)] is preferably 5/95 to 90/10 from the viewpoint of dispersion stability of the polymer particles, and preferably 10/90 to 75/25. Is more preferable, and 20/80 to 50/50 is particularly preferable.

The average particle diameter of the polymer particles in the obtained pigment dispersion and inkjet recording water-based ink is as described above. The water content in the pigment dispersion of the present invention and the water-based ink for inkjet recording is preferably 30 to 90% by weight, more preferably 40 to 80% by weight. The water-based ink is an ink using water as a main solvent.
The ink jet method to which the water-based ink is applied is not limited, and is suitable for a thermal method and a piezo method ink jet printer.

In the following production examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified.
Production Example 1
In a reaction vessel, 20 parts of methyl ethyl ketone, 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol), and 10% of 200 parts of each monomer shown in Table 1 were mixed and thoroughly replaced with nitrogen gas. A mixed solution was obtained.
On the other hand, the remaining 90% of the monomers shown in Table 1 were charged into a dropping funnel, and 0.27 part of the polymerization chain transfer agent, 60 parts of methyl ethyl ketone and a radical polymerization initiator (2,2′-azobis (2,4-dimethyl) were added. Valeronitrile)) 1.2 parts were 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 65 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped over 3 hours. After 2 hours at 65 ° C. from the end of dropping, a solution in which 0.3 part of the radical polymerization initiator was dissolved in 5 parts of methyl ethyl ketone was added, and further aged at 65 ° C. for 2 hours and at 70 ° C. for 2 hours, and further 115 parts of methyl ethyl ketone. In addition, the mixture was stirred for 30 minutes to obtain a polymer solution having a polymer concentration of 50%.
The weight average molecular weight of the obtained polymer was measured by the above method. The results are shown in Table 1.
The details of the compounds shown in Table 1 are as follows.
(B) Styrene macromer, manufactured by Toa Gosei Co., Ltd., trade name: AS-6S, number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group (d) M-90G
Polyethylene glycol monomethacrylate (ethylene oxide average addition mole number = 9): Shin-Nakamura Chemical Co., Ltd., trade name: NK ester M-90G
(D) PP-500
Polypropylene glycol monomethacrylate (propylene oxide average added mole number = 9): manufactured by NOF Corporation, trade name: BLEMMER PP-500

[Calculation of log P value]
The LogP value of the polymer synthesized in Production Example 1 (methacrylic acid / benzyl methacrylate / styrene macromer / styrene / M-90G / PP-500 = 10 parts / 40 parts / 15 parts / 10 parts / 5 parts / 20 parts) is Is calculated as follows.
The LogP value of methacrylic acid is 0.99 (molecular weight: 86), the LogP value of benzyl methacrylate is 2.98 (molecular weight: 176), the LogP value of styrene is 2.89 (molecular weight: 104), and the styrene macromer is Since about 57 mol of styrene is added to the basic structure of methacrylic acid, its LogP value is 165.72 (= 0.99 + 57 × 2.89).
M-90G:
Polyethylene glycol monomethacrylate (average number of moles of ethylene oxide added = 9): It has a methacryloyloxy group, 9 moles of ethylene oxide is added, and the terminal is a methyl group. It has 9 moles of oxide. Since the log P value of ethylene oxide is −0.27 and the log P value of methacrylic acid is 0.99, the log P value of M-90G is −0.89 (= 0.99−0.27 × 9 + 0. 55, molecular weight: 496).
PP-500:
Polypropylene glycol monomethacrylate (propylene oxide average addition mole number = 9): It has a methacryloyloxy group, 9 mol of propylene oxide is added, and the terminal is a hydrogen atom. It has 9 moles of propylene oxide. Since the LogP value of propylene oxide is 0.14 and the LogP value of methacrylic acid is 0.99, the LogP value of PP-500 is 2.25 (= 0.99 + 0.14 × 9, molecular weight: 608). Is calculated.
The total number of moles of each monomer is 0.485 (= 10/86 + 15/6000 + 40/176 + 10/104 + 5/496 + 20/608).
The LogP value of the polymer synthesized in Production Example 1 is the sum of the values obtained by multiplying the LogP value of each monomer by the mol% of each monomer, and therefore 3.20 [= 0.99 × 10/86/0. .485 + 2.98 × 40/176 / 0.485 + 165.72 × 15/6000 / 0.485 + 2.89 × 10/104 / 0.485 + (− 0.89) × 5/496 / 0.485 + 2.25 × 20 /608/0.485].

Example 1
[Production process of water-insoluble organic compound-containing polymer emulsion]
200 parts of the polymer solution obtained in Production Example 1, 100 parts of methyl ethyl ketone (boiling point (1 atm): 79 ° C.), 100 parts of acetone (boiling point (1 atm): 56 ° C.), toluene (boiling point (1 atm)) ): 111 ° C.) 100 parts and 43 parts of a water-insoluble organic compound (dibutyl sebacate) are stirred for 30 minutes until uniform, and a mixed solution of an organic solvent containing a polymer and a water-insoluble organic compound (hereinafter referred to as organic solvent). Obtained).
On the other hand, after stirring 16.5 parts of 5N NaOH aqueous solution and 500 parts of ion-exchanged water in a 2000 ml beaker until the whole was mixed, the whole mixed solution of the organic solvent was added and stirred for 15 minutes. Using an ultrasonic homogenizer (MODEL: US-300T) manufactured by Seiki Seisakusho, dispersion treatment is performed at 200 μA for 20 minutes, and the organic solvent is removed at 60 ° C. under reduced pressure until the content becomes about 1%. Then, a water-insoluble organic compound-containing polymer emulsion having a solid content concentration of 40% was obtained.

[Production process of pigment dispersion]
114.1 parts of the above water-insoluble organic compound-containing polymer emulsion, 294.7 parts of ion-exchanged water, 2.78 parts of 25% aqueous ammonia, and phthalocyanine pigment (cyan: C) as a pigment (CI Pigment Blue 15: 4 [P.B. 15: 4], manufactured by Toyo Ink Manufacturing Co., Ltd., trade name: LIONOGEN BLUE BGJ) was added and mixed with a disper blade at 20 ° C. for 1 hour. The obtained mixture was subjected to a 15-pass dispersion treatment with a microfluidizer (trade name, manufactured by Microfluidics) at a pressure of 200 MPa. The obtained dispersion was reduced under reduced pressure at 60 ° C. until the content of the organic solvent was 0.01% or less, part of the water was removed, and a high-speed cooling centrifuge manufactured by Hitachi Koki Co., Ltd. ( After performing centrifugation at 4300 RPM for 20 minutes using MODEL: CR22G), a needleless syringe with a capacity of 25 mL equipped with a 5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) By filtering through (made by Terumo Corporation) and removing coarse particles, a pigment dispersion having a solid content concentration of 20% was obtained.

[Manufacture of water-based ink]
27.8 parts of the obtained pigment dispersion, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfinol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), Proxel XL2 (manufactured by Avicia Co., Ltd.) ) 0.3 part and 53.9 parts of ion-exchanged water were mixed, and a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) was attached to the resulting mixture. The aqueous ink shown in Table 2 was obtained by filtering with a syringe having a capacity of 25 mL and removing coarse particles.

Example 2
In the production process of the pigment dispersion of Example 1, instead of using 294.7 parts of ion-exchanged water, the water-based ink shown in Table 2 was used in the same manner as in Example 1 except that 105 parts of methyl ethyl ketone and 189.7 parts of ion-exchanged water were used. Got.

Example 3
In the production process of the water-insoluble organic compound-containing polymer emulsion of Example 2, a water-insoluble organic compound (octylbenzyl phthalate) is used instead of the water-insoluble organic compound (dibutyl sebacate), and the pigment dispersion production process of Example 2 In this case, a quinacridone pigment (CI Pigment Violet 19 [P.V.19], manufactured by Clariant Japan Co., Ltd., trade name: HostapermRed E5B02) is used instead of the phthalocyanine pigment, and the pigment dispersion used in the production of the water-based ink is used. A water-based ink shown in Table 2 was obtained in the same manner as in Example 2 except that 27.8 parts were changed to 38.65 parts and ion-exchanged water 53.9 parts were changed to 43.05 parts.

Example 4
In the production process of the pigment dispersion of Example 3, the pigment was replaced with a diazo pigment (yellow: Y) (CI Pigment Yellow 74 [PY 74], manufactured by Sanyo Dye Co., Ltd.) instead of the quinacridone pigment. A water-based ink shown in Table 2 was obtained in the same manner as in Example 3 except that the name was FY7413).

Comparative Example 1
A pigment dispersion having a solid content concentration of 20% was obtained in the same manner as in Example 2 except that the water-insoluble organic compound (dibutyl sebacate) was not used in the production process of the water-insoluble organic compound-containing polymer emulsion of Example 2.
25.8 parts of pigment dispersion of the obtained pigment-containing polymer particles, 0.5 part of water-insoluble organic compound (dibutyl sebacate), 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfinol 465 Then, 0.3 part of Proxel XL2 and 55.4 parts of ion-exchanged water were mixed, and the obtained liquid mixture was filtered with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.). The aqueous ink shown in Table 3 was obtained by filtering with an attached syringe without a needle of 25 mL to remove coarse particles.

Comparative Example 2
A pigment dispersion having a solid content concentration of 20% was obtained in the same manner as in Example 3 except that the water-insoluble organic compound (octylbenzyl phthalate) was not used in the production process of the water-insoluble organic compound-containing polymer emulsion of Example 3. 36.15 parts of pigment dispersion of the obtained pigment-containing polymer particles, 0.5 part of a water-insoluble organic compound (octylbenzyl phthalate), 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfinol 465 , 0.3 parts of Proxel XL2 and 45.05 parts of ion-exchanged water were mixed, and the obtained liquid mixture was filtered with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.). The aqueous ink shown in Table 3 was obtained by filtering with an attached syringe without a needle of 25 mL to remove coarse particles.

Comparative Example 3
A pigment dispersion having a solid content concentration of 20% was obtained in the same manner as in Example 4 except that the water-insoluble organic compound (octylbenzyl phthalate) was not used in the production process of the water-insoluble organic compound-containing polymer emulsion of Example 4. 36.15 parts of pigment dispersion of the obtained pigment-containing polymer particles, 0.5 part of a water-insoluble organic compound (octylbenzyl phthalate), 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfinol 465 , 0.3 parts of Proxel XL2 and 45.05 parts of ion-exchanged water were mixed, and the obtained liquid mixture was filtered with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.). The aqueous ink shown in Table 3 was obtained by filtering with an attached syringe without a needle of 25 mL to remove coarse particles.

Comparative Example 4
The water-based inks shown in Table 3 were used in the same manner as in Comparative Example 1 except that the water-insoluble organic compound (dibutyl sebacate) was not used in the water-based ink manufacturing process and 55.4 parts of ion-exchanged water was changed to 55.9 parts. Obtained.

Next, the performances of the inks obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were measured according to the following method. The results are shown in Tables 2 and 3.
[Evaluation methods]
(1) Oil floating The presence or absence of oil droplets of a water-insoluble organic compound present on the ink surface was visually evaluated according to the following criteria.
○: There are no oil droplets.
X: Oil droplets exist.
(2) Image clarity Using the printer, solid printing was performed on commercially available special paper (photographic paper <gloss> manufactured by Seiko Epson Corporation, trade name: KA450PSK) [printing condition = paper type: photo print paper, mode setting: photo ] After leaving at 25 ° C. for 24 hours, a 45 ° image clarity C (%) (comb width 2.0 mm) was applied to an image clarity measuring instrument (trade name: touch panel type image clarity measuring instrument, manufactured by Suga Test Instruments Co., Ltd.) : ICM-IT) was measured three times, and the average value was determined.
The image clarity is to measure the sharpness or distortion when the image is reflected on the printed matter. When the numerical value is larger, the reflected image is clearer and less distorted, and the reflected image looks natural.

＊１，ジブチルセバケートのＬｏｇ Ｐ：６．３０
＊２，オクチルベンジルフタレートのＬｏｇ Ｐ：６．７９

* 1, Dibutyl sebacate Log P: 6.30
* 2, Log P of octylbenzyl phthalate: 6.79

Claims (9)

The manufacturing method of the pigment dispersion which has the following process (I) and process (III).
Step (I): a step of mixing a water-insoluble polymer (A), a water-insoluble organic compound (B), an organic solvent (C) and water to obtain a mixture containing them ,
The water-insoluble polymer (A) is (a) a salt-forming group-containing monomer, (b) a macromer, (c) a hydrophobic monomer, (d) a hydroxyl group-containing monomer, and (e) a monomer represented by the following formula (1) Each of which is produced by copolymerizing two or more monomer mixtures alone, having a weight average molecular weight of 5,000 to 500,000, dried at 105 ° C. for 2 hours, and then dissolved in 100 g of water at 25 ° C. The amount of dissolution when it is made to be 10 g or less,
_{^{CH 2 = C (R 1)}} COO (R 2 O) p R 3 (1)
Wherein R ¹ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ² is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ³ is A monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, p means an average number of added moles, and represents a number of 1 to 60.)
The water-insoluble organic compound (B) has two or more ester or ether bonds in the molecule, carboxylic acid ester, phosphate ester or ether compound, or one or more ester or ether bonds in the molecule, A carboxylic acid ester, a phosphoric acid ester or an ether compound having at least one functional group selected from the group consisting of carboxylic acid, phosphoric acid residue, carbonyl group, epoxy group and hydroxyl group, and having a molecular weight of 100 to The amount dissolved at 2,000 and 100 g of water (20 ° C.) is 5 g or less .
Step (III): A step of mixing the mixture and the pigment (D) and then dispersing to obtain a pigment dispersion. The process for producing a pigment dispersion according to claim 1, which comprises the following step (II) after step (I).
Step (II): A step of obtaining a mixture from which at least a part of the organic solvent (C) has been removed from the mixture.   The method for producing a pigment dispersion according to claim 1 or 2, wherein the content of the organic solvent in the mixture in step (III) is 35% by weight or less.   The method for producing a pigment dispersion according to any one of claims 1 to 3, wherein the step (III) includes a step of removing the organic solvent after the dispersion treatment.   The LogP value of the water-insoluble organic compound (B) is -1 to 11, The method for producing a pigment dispersion according to any one of claims 1 to 4.   The method for producing a pigment dispersion according to any one of claims 1 to 5, wherein the boiling point of the organic solvent (C) is 150 ° C or lower.   The water-insoluble polymer (A) is a water-insoluble vinyl polymer obtained by copolymerizing a monomer mixture containing (a) a salt-forming group-containing monomer and (b) a macromer and / or (c) a hydrophobic monomer. 7. A method for producing a pigment dispersion as described in any one of 6 above. The method for producing a pigment dispersion according to any one of claims 1 to 7, wherein the pigment dispersion is for inkjet recording.   The manufacturing method of the water-based ink for inkjet recording which has the process of manufacturing a pigment dispersion using the manufacturing method in any one of Claims 1-8.