JP5164352B2 - Water-based ink for inkjet recording - Google Patents

Description

  The present invention relates to an aqueous ink for inkjet recording, an aqueous dispersion used in the ink, and a method for producing crosslinked core-shell polymer particles.

The ink jet recording system is a recording system in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle and attaching them to a recording member. This method is widely spread because it is easy to make full color and is inexpensive, and has many advantages such as the ability to use plain paper as a recording member and non-contact with the object to be printed.
Among them, from the viewpoint of weather resistance and water resistance of printed materials, those using pigment-based inks as colorants have become mainstream, but when pigments are used as colorants, reflected light depends on the observation angle of printed materials. A bronzing phenomenon may occur in which a color different from the original color of the pigment is observed. For example, a phthalocyanine pigment contained in cyan ink may cause the reflected light to be colored red, which may significantly deteriorate the image quality. The bronze phenomenon is described in detail in “Color Science Handbook” (University of Tokyo Press), page 777.
In order to improve this bronze phenomenon, an ink composition containing a polyether-modified polysiloxane and a sulfone group-containing (co) polymer emulsion (Patent Document 1), an ink containing a polycyclic aromatic heteroconjugated compound (Patent Document 2) ) Etc. have been proposed. However, in these methods, there are concerns about adverse effects on print image quality due to additives and pigment changes.

  On the other hand, an aqueous dispersion of colored fine particles having a core / shell structure and an aqueous ink are known. For example, in order to improve durability, an ink in which a colorant combined with a primer core / shell polymer is encapsulated with a durable core / shell polymer (Patent Document 3), in order to improve image peelability after recording, Ink in which colored resin particles having at least a core made of a colorant and a thermoplastic resin and a shell made of a resin having a three-dimensional crosslinked structure are present in a capsule emulsion state (Patent Document 4), improving ejection stability and light resistance In order to improve the solvent resistance, an aqueous dispersion having colored fine particles containing two or more kinds of resins and coloring materials as a core (Patent Document 5) has a core-shell structure with at least two layers of fine particles. A colored fine particle dispersion (Patent Document 6) in which two or more of the core and the shell have a crosslinked structure has been proposed. However, these water dispersions and inks do not improve the bronzing phenomenon.

JP 2003-306620 A JP 2004-67903 A Special table 2003-520279 gazette Japanese Patent Laid-Open No. 2002-12802 JP 2003-206430 A JP 2004-269558 A

  An object of the present invention is to provide a water-based ink for ink-jet recording excellent in improving printing density and glossiness and suppressing bronzing, an aqueous dispersion used in the ink, and a method for producing a crosslinked core-shell polymer particle. .

The present invention provides the following (1) to (4).
(1) An aqueous dispersion for ink jet recording comprising water-insoluble crosslinked polymer particles (A) and core-shell polymer particles (B) containing a colorant.
(2) An aqueous dispersion for ink jet recording containing water-insoluble crosslinked polymer particles (A) and crosslinked polymer particles (C) containing a colorant.
(3) A water-based ink for ink-jet recording containing the water dispersion of (1) or (2).
(4) A method for producing a crosslinked core-shell polymer particle, comprising the following steps 1 to 3.
Step 1: A water-insoluble polymer, a crosslinkable monomer having at least two reactive unsaturated groups in the molecule, an organic solvent, a hydrophobic monomer, and an emulsion composition containing water are obtained. Step 2: Obtained in Step 1 Step 3: Obtaining a dispersion of core-shell polymer particles obtained by polymerizing the hydrophobic monomer and the crosslinkable monomer in the obtained emulsified composition to crosslink the core portion. The core portion obtained in Step 2 is crosslinked. A step of reacting the core-shell polymer particles thus obtained with a crosslinking agent having at least two reactive functional groups

The water-based ink for ink-jet recording of the present invention is excellent in print density when printed on plain paper, and can give a printed matter with improved gloss and suppression of bronze phenomenon when printed on special paper. .
Further, according to the method of the present invention, crosslinked core-shell polymer particles that can be contained in the water-based ink for inkjet recording can be efficiently produced.

The aqueous dispersion for inkjet recording and the water-based ink of the present invention are characterized by containing water-insoluble crosslinked polymer particles (A) containing a colorant, and core-shell polymer particles (B) or crosslinked polymer particles (C). By containing the water-insoluble crosslinked polymer particles (A) containing the colorant and the core-shell polymer particles (B) or the crosslinked polymer particles (C), water excellent in improving the printing density and glossiness and suppressing the bronze phenomenon It can be a dispersion or water-based ink.
Hereinafter, the water-insoluble crosslinked polymer particles (A) containing a colorant may be referred to as “colorant-containing crosslinked polymer particles (A)”, and the water-insoluble crosslinked polymer is simply referred to as “crosslinked polymer (A)”. There are times.

(Coloring agent)
The colorant is not particularly limited, and pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.) can be used, but from the viewpoint of water resistance, dispersion stability, and scratch resistance. Pigments and hydrophobic dyes are preferred. Among them, it is preferable to use a pigment in order to express the high weather resistance which has been recently demanded.
When the pigment and the hydrophobic dye are used in an aqueous ink, it is necessary to use a surfactant and a polymer to form fine particles that are stable in the ink. In particular, from the viewpoints of bleeding resistance, water resistance, and the like, it is preferable to include a pigment and / or a hydrophobic dye in the polymer particles.
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, and C.I. I. One or more types of products selected from the group consisting of pigment green are listed.
Examples of extender pigments include silica, calcium carbonate, and talc.

The hydrophobic dye should just be what can be contained in the particle | grains of a crosslinked polymer (A), and there is no restriction | limiting in particular in the kind. The hydrophobic dye is dissolved in an amount of 2 g / L or more, preferably 20 to 500 g / L (25 ° C.) with respect to the organic solvent (preferably methyl ethyl ketone) used in the production of the polymer from the viewpoint of efficiently containing the dye in the polymer. What to do is desirable.
Examples of the hydrophobic dye include oil-soluble dyes and disperse dyes. Among these, oil-soluble dyes are preferable.
Examples of the oil-soluble dye include C.I. I. Solvent Black, C.I. I. Solvent Yellow, C.I. I. Solvent Red, C.I. I. Solvent Violet, C.I. I. Solvent Blue, C.I. I. Solvent Green, and C.I. I. One or more types of products selected from the group consisting of Solvent Orange are listed, which are commercially available from Orient Chemical Co., Ltd., BASF Corp. and others.
Among these, from the viewpoint of enhancing the effect of reducing the bronzing phenomenon, it is preferable to use a cyan pigment, and a phthalocyanine pigment is more preferable. Specifically, a copper phthalocyanine pigment is preferable. I. One or more selected from the group consisting of CI Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 16 and 60 are preferred. The above colorants can be used alone or in admixture of two or more at any ratio.

(Water-insoluble polymer)
The water-insoluble polymer used in the present invention is crosslinked with a crosslinking agent to form a crosslinked polymer (A). Here, the water-insoluble polymer means that when the polymer is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolution amount is 10 g or less, preferably 5 g or less, more preferably 1 g or less. Is a polymer. 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.
Examples of the polymer to be used include polyester, polyurethane, and vinyl polymer. From the viewpoint of dispersion stability, a vinyl polymer obtained by addition polymerization of a vinyl monomer (vinyl compound, vinylidene compound, vinylene compound) is preferable.

(Vinyl polymer)
As the vinyl polymer, (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 water-insoluble vinyl polymer obtained by copolymerizing a monomer mixture (hereinafter also referred to as “monomer mixture”) containing a hydrophobic monomer (hereinafter also referred to as “component (c)”) is preferable. This water-insoluble vinyl 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). A more preferred water-insoluble vinyl polymer has a structural unit derived from the component (a) or a structural unit derived from the components (a) and (c) as a main chain, and a structural unit derived from the component (b) as a side chain. It is a water-insoluble 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.
Examples of the salt-forming group-containing monomer include cationic monomers and anionic monomers described in JP-A-9-286939, paragraph [0022].
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.

(B) The macromer is used from the viewpoint of enhancing the dispersion stability of the colorant-containing crosslinked polymer particles (A). 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 chloroform containing 1 mmol / L of dodecyldimethylamine as a solvent.
Among the macromers, from the viewpoint of dispersion stability of the colorant-containing crosslinked polymer particles (A), a styrenic macromer and an aromatic group-containing (meth) acrylate macromer having a polymerizable functional group at one end. Is preferred.
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.

(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 (1).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _{t -Si (CH 3) 3 (} 1)
(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” indicates acrylate, methacrylate, or both.

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), a styrene monomer (c-1 component) is preferable from the viewpoint of improving printing density, and styrene and 2-methylstyrene are particularly preferable as the styrene monomer. 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.
Moreover, as an aromatic group containing (meth) acrylate (c-2) component, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, etc. 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 printing density and gloss. 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)”). (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.

The monomer mixture may further contain (e) a monomer represented by the following formula (2) (hereinafter sometimes referred to as “(e) component”).
CH ₂ = C (R ¹ ) COO (R ² O) _q R ³ (2)
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 or a phenyl group optionally having an alkyl group having 1 to 9 carbon atoms, q means the average number of moles added. , 1 to 60, preferably 1 to 30.)
(E) component expresses the outstanding effect of improving discharge property.
In the formula (2), 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 oxytrimethylene grave, an oxypropane-1,2-diyl group, an oxytetramethylene group, an oxyheptamethylene group, an oxyhexamethylene group, and two or more kinds thereof. Examples thereof include oxyalkanediyl groups having 2 to 7 carbon atoms (oxyalkylene groups).
Preferable examples of R ³ include an aliphatic alkyl group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, an alkyl group having 7 to 30 carbon atoms having an aromatic ring, and Examples thereof include an alkyl group having 4 to 30 carbon atoms having a heterocycle and a phenyl group optionally having an alkyl group having 1 to 8 carbon atoms.

  Specific examples of the component (e) include methoxypolyethylene glycol (1 to 30: the value of q in the formula (2), 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) 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 (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, 43PAPE600B, 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 (content as an unneutralized amount; the same applies hereinafter) or the water-insoluble vinyl polymer (a) to (e) ) The content of the structural unit derived from the component is as follows.
The content of component (a) is preferably 2 to 40% by weight, more preferably 2 to 30% 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 with the colorant.
The content of the component (c) is preferably 5 to 98% by weight, more preferably 10 to 60% by weight, from the viewpoint of improving print density.
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 the component (e) is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of improving dischargeability.
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 and dischargeability of the resulting dispersion. . Moreover, the total content of [(a) component + (d) component + (e) component] is preferably 6 to 60% by weight, more preferably from the viewpoint of dispersion stability and dischargeability of the resulting dispersion. 7 to 50% by weight.
The weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.01 to 1, more preferably from the viewpoint of dispersion stability and print density of the resulting dispersion. Is 0.02 to 0.67, more preferably 0.03 to 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 from 5,000 to 500,000, more preferably from 10,000 to 400,000, from the viewpoints of printing density, glossiness, and dispersion stability of the colorant. ˜300,000 is more preferable, and 20,000 to 300,000 is particularly preferable. In addition, the weight average molecular weight of the polymer was measured by the method shown in the Examples.
When the water-insoluble vinyl 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, triethylamine, 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 formulas (3) and (4) 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 (3)
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 (4)
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.

(Crosslinking agent)
The crosslinking agent used in the production of the colorant-containing crosslinked polymer particles (A) is a crosslinking agent having at least two reactive functional groups (hereinafter also simply referred to as “crosslinking agent”) in order to moderately crosslink the water-insoluble polymer. ) Is preferred. The molecular weight of the cross-linking agent is preferably 120 to 2000, more preferably 150 to 1500, and particularly preferably 150 to 1000, from the viewpoint of easy reaction and storage stability of the resulting cross-linked polymer particles.
The number of reactive functional groups is preferably 2 to 4 and most preferably 2 from the viewpoint of improving the gloss by controlling the molecular weight. The reactive functional group is preferably at least one selected from the group consisting of a hydroxyl group, an epoxy group, an aldehyde group, an amino group, and a carboxy group.
As a specific example of the crosslinking agent,
(A) Compound having two or more hydroxyl groups in the molecule: for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, 1,4-butanediol, 1,5-pentane Diols, 1,6-hexanediol, neopentyl alcohol, diethanolamine, tridiethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, sorbitol, sorbitan, glucose, mannitol, mannitan, sucrose, glucose and other polyhydric alcohols,
(B) compounds having two or more epoxy groups in the molecule: for example, polyglycidyl ethers such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether,
(C) Compounds having two or more aldehyde groups in the molecule: for example, polyaldehydes such as glutaraldehyde and glyoxal,
(D) Compound having two or more amino groups in the molecule: for example, polyamines such as ethylenediamine and polyethyleneimine, and (e) Compound having two or more carboxy groups in the molecule: for example, oxalic acid, malonic acid And polyvalent carboxylic acids such as succinic acid, fumaric acid, maleic acid and adipic acid.

The water-insoluble polymer has a reactive group (crosslinkable functional group) capable of reacting with the crosslinking agent, and a suitable combination example of both is as follows.
When the reactive group of the water-insoluble polymer is an acidic group such as a carboxy group, a sulfonic acid group, or a phosphoric acid group, the above-mentioned compounds (a), (b) and (d) are preferred as the crosslinking agent.
When the reactive group of the water-insoluble polymer is an amino group or a hydroxyl group, the crosslinking agent is preferably the compounds (b), (c) and (e).
When the reactive group of the water-insoluble polymer is an isocyanate group or an epoxy group, the crosslinking agent is preferably the compounds (a), (d) and (e).
Among the above combinations, one type selected from an acidic group (carboxy group, sulfonic acid group, phosphoric acid group, etc.), amino group and hydroxyl group from the viewpoint of controlling the water-insoluble polymer so as to impart an appropriate crosslinking structure. A combination of the above water-insoluble polymer having a reactive group and (b) a compound having two or more epoxy groups in the molecule is particularly preferred.

A water-insoluble polymer having an acidic group such as a carboxy group, a sulfonic acid group, and a phosphoric acid group, an amino group, a hydroxyl group, an isocyanate group, and an epoxy group as a reactive group (crosslinkable functional group) that can react with the crosslinking agent is In the production of the above water-insoluble polymer, it can be produced by copolymerizing a polymerizable monomer composition containing a monomer having the reactive group.
As the polymer having a reactive group capable of reacting with the crosslinking agent, the polymer having a salt-forming group such as an acidic group or an amino group can be a polymer obtained by copolymerizing the aforementioned salt-forming group-containing monomer. As the polymer having, a polymer obtained by copolymerizing the above-mentioned hydroxyl group-containing monomer can be used.
As the polymer having an epoxy group, a monomer having an epoxy group, specifically, a polymer obtained by copolymerizing glycidyl (meth) acrylate can be used. As the polymer having an isocyanate group, (i) a monomer having an isocyanate group, for example, a polymer copolymerized with isocyanate ethyl (meth) acrylate, (ii) an isocyanate-terminated prepolymer obtained from an unsaturated polyester polyol and isocyanate was copolymerized. A polymer or the like can be used.

(Water-insoluble crosslinked polymer particles (A) containing a colorant)
In the present invention, the colorant-containing cross-linked polymer particles (A) improve the printing density and gloss by interaction with the core-shell polymer particles (B) or the cross-linked polymer particles (C), and suppress the bronzing phenomenon. Used.
It is considered that the cross-linked polymer (A) can prevent fusion between particles due to swelling of the polymer by having an appropriate cross-linked structure.
The colorant-containing crosslinked polymer particles (A) are produced by (i) Step I for obtaining water-insoluble polymer particles containing a colorant using a colorant and a water-insoluble polymer, and the color obtained in Step I. A step of obtaining water-insoluble polymer particles containing an agent by crosslinking with a crosslinking agent to obtain crosslinked polymer particles, and (ii) a step of obtaining a water-insoluble crosslinked polymer by crosslinking the water-insoluble polymer with a crosslinking agent. Examples thereof include a method of production by III and Step IV of obtaining crosslinked polymer particles using the water-insoluble crosslinked polymer obtained in Step III and a colorant. In these, the method by said (i) is preferable from manufacturing ease.

The manufacturing method by said (i) can be performed by the following process (1)-(3), for example.
Step (1): A step of dispersing a mixture containing a water-insoluble polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent to obtain a dispersion of water-insoluble polymer particles containing the colorant. 2): Step of removing the organic solvent from the dispersion obtained in step (1) to obtain an aqueous dispersion of water-insoluble polymer particles containing a colorant. Step (3): Obtained in step (2) A step of obtaining a colorant-containing crosslinked polymer particle (A) by reacting an aqueous dispersion of water-insoluble polymer particles containing a colorant with a crosslinking agent.

In step (1), first, the water-insoluble polymer is dissolved in an organic solvent, and then a colorant, water, and, if necessary, a neutralizing agent and a surfactant are added to the obtained organic solvent solution. A method of mixing to obtain an oil-in-water dispersion is preferred. In the mixture, the colorant 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 water-insoluble 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 water-insoluble polymer has a salt-forming group, it is preferable to use a neutralizing agent. There is no particular limitation on the degree of neutralization when neutralizing with a neutralizer. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 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. Further, the water-insoluble 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 and diethyl ketone, and ether solvents such as dibutyl ether, tetrahydrofuran and dioxane. The solubility in water is preferably 50% by weight or less and 10% by weight or more at 20 ° C., and methyl ethyl ketone is particularly preferable.

There is no restriction | limiting in particular in the dispersion method of the mixture in process (1). 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 and dispersion | distribution of a process (1) has more preferable 10-35 degreeC.
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 Co., Ltd., trade name], Ebara Milder [Ebara Seisakusho Co., Ltd., trade 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.
As means for applying the shear stress of this dispersion, for example, a kneader such as a roll mill, a bead mill, a kneader, an extruder, a high-pressure homogenizer (Izumi Food Machinery Co., Ltd., trade name), a minilab 8.3H type (Rannie Co., trade name) Representative homo-valve type high-pressure homogenizer, microfluidizer (Microfluidics, trade name), nanomizer (Nanomizer, trade name), optimizer (Sugino machine, trade name), Genus PY (Shiramizu Chemical Co., Ltd.) Product name], DeBEE2000 [Japan EE Co., Ltd., product name] and the like chamber type high-pressure homogenizer. A plurality of these devices can be combined. Among these, when a pigment is used, a high-pressure homogenizer is preferable from the viewpoint of reducing the particle size of the pigment.

In the step (2), an aqueous dispersion of polymer particles containing a colorant can be obtained by distilling off the organic solvent from the obtained dispersion by a known method to form an aqueous system. The organic solvent in the aqueous dispersion containing the obtained polymer particles is substantially removed. The amount of the residual organic solvent is preferably 0.1% by weight or less, and more preferably 0.01% by weight or less.
The obtained aqueous dispersion of polymer particles containing the colorant is one in which the solid content of the polymer containing the colorant is dispersed in water as the main solvent. Here, the form of the polymer particles is not particularly limited as long as the particles are formed of at least a colorant and a polymer. For example, a particle form in which a colorant is included in a polymer, a particle form in which a colorant is uniformly dispersed in a polymer, a particle form in which a colorant is exposed on the surface of a polymer particle, and the like are included.

In the step (3), the obtained polymer particles containing the colorant are reacted with the crosslinking agent to obtain the colorant-containing crosslinked polymer particles (A). Depending on the crosslinking agent used, the catalyst, solvent, temperature, and time can be appropriately selected and used.
The reaction time is preferably 0.5 to 10 hours, more preferably 1 to 5 hours, and the reaction temperature is preferably 40 to 95 ° C.
The amount of the crosslinking agent used is preferably 0.1 parts by weight or more, more preferably 0.3 parts by weight or more, and more preferably 0.5 parts by weight with respect to 100 parts by weight of the water-insoluble polymer from the viewpoint of gloss and storage stability. More preferred is 1 part by weight or more, and most preferred is 1.5 parts by weight or more. Further, the upper limit is preferably 15 parts by weight or less, more preferably 10 parts by weight or less, still more preferably 8 parts by weight or less, particularly preferably 6.5 parts by weight or less, and most preferably 6 parts by weight or less. From these viewpoints, 0.1 to 15 parts by weight is preferable, 0.3 to 10 parts by weight is more preferable, 0.5 to 8 parts by weight is still more preferable, and 1 to 7.5 parts by weight is still more preferable. -6.5 parts by weight is particularly preferred, and 1.5-6 parts by weight is most preferred.

The crosslinking rate (mol%) of the crosslinked polymer (A) is preferably 1 to 80%, more preferably 3 to 60%, and particularly preferably from the viewpoint of improvement in printing density, glossiness, and suppression of bronze phenomenon. 5 to 50%. Here, the crosslinking rate (mol%) of the crosslinked polymer refers to a value determined by the following formula (5).
Crosslinking rate (mol%) = [number of moles of crosslinking agent to be reacted with 1 mole of water-insoluble polymer × 100 / number of moles of reactive group capable of reacting with crosslinking agent of 1 mole of water-insoluble polymer] (5)
Here, “the number of molar equivalents of the crosslinking agent to be reacted with 1 mol of the water-insoluble polymer” is obtained by multiplying the number of moles of the crosslinking agent to be reacted with 1 mol of the water-insoluble polymer by the number of reactive groups in one molecule of the crosslinking agent. Value.

(Water-insoluble organic compound)
In the present invention, a water-insoluble organic compound can be used from the viewpoint of improving the flexibility of the crosslinked polymer particles and improving the gloss of the printed matter.
From the viewpoint of improving the glossiness of the water-based ink, the water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, more preferably a molecular weight of 100 to 1,200.
The amount of the water-insoluble organic compound dissolved in 100 g of water (20 ° C.) is preferably 5 g or less, more preferably 3 g or less, still more preferably 1 g or less, and particularly preferably 0.5 g or less.
The water-insoluble organic compound improves the glossiness of the printed matter when printed on special paper and also improves the storage stability of the aqueous dispersion from its LogP value (water-insoluble organic compound 1-octanol / water). The logarithmic value of the distribution coefficient is preferably 4 to 16, more preferably 5 to 16, and particularly preferably 6 to 15.

The water-insoluble organic compound is preferably an ester compound, an ether compound, or a sulfonic acid amide compound so as to be easily contained in the (crosslinked) polymer particle, and an ester having two or more ester or ether bonds in the molecule. Or selected from the group consisting of an ether compound (x) and / or one or more ester or ether bonds in the molecule and a carboxy group, a sulfonic acid group, a phosphoric acid residue, a carbonyl group, an epoxy group and a hydroxyl group. An ester or ether compound (y) having one or more, preferably 1 to 3 functional groups, is more preferred. The number of ester or ether bonds in the compound (x) is preferably 2 to 3. The number of ester or ether bonds in the compound (y) is preferably 1 to 3.
Among the ester compounds, esters obtained from monovalent carboxylic acids or salts thereof and polyhydric alcohols, polyacids (polycarboxylic acids, phosphoric acids) or esters obtained from salts thereof and monohydric alcohols are preferred, and ether compounds Of these, polyhydric alcohol ethers are preferred. Examples of the salt include alkali metal salts, alkanolamine salts, ammonium salts and the like.

Examples of monovalent carboxylic acids include linear or branched aliphatic carboxylic acids having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms, and aromatic carboxylic acids having 6 to 12 carbon atoms (for example, benzoic acid). Can be mentioned. Examples of the polyvalent acid include aliphatic carboxylic acids having 2 to 12 carbon atoms such as maleic acid, fumaric acid, itaconic acid, succinic acid, adipic acid and sebacic acid, and 6 to 12 carbon atoms such as phthalic acid and trimellitic acid. Aromatic carboxylic acid, phosphoric acid and the like can be mentioned.
As the monohydric alcohol, 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, dodecyl alcohol), carbon number 6-12 aromatic alcohol (for example, phenol), these alkylene oxide compounds, etc. are mentioned.
Examples of the polyhydric alcohol include polyhydric alcohols having 2 to 12 carbon atoms such as ethylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and glycerin, and alkylene oxide compounds thereof. 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) cycloalkane (ken) carboxylic acid ester obtained from the above carboxylic acid, alcohol and the like. (4) Phosphate ester, (5) Oxy acid ester, (6) Glycol ester, (7) Epoxy ester, (8) Sulfonamide, (9) Polyester, (10) Glyceryl alkyl ether, (11) Glyceryl alkyl Examples include esters and (12) glycol alkyl ethers.
Among these, from the viewpoint of improving glossiness, the compounds of (1) to (5), (8) and (10) are preferable, (1) aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester. , (3) one or more selected from the group consisting of cycloalkane (ken) carboxylic acid ester and (4) phosphoric acid ester, and more preferably aliphatic dicarboxylic acid ester, aromatic di- or tricarboxylic acid ester, cyclohexane It is especially preferable that it is 1 or more types chosen from the group which consists of alkane (ken) dicarboxylic acid ester and phosphoric acid di or triester.

(Core-shell polymer particles (B) and crosslinked polymer particles (C))
In the present invention, the core-shell polymer particle (B) means a polymer having a structure in which a polymer constituting the shell part is physically or chemically bonded to a polymer constituting the core part.
From the viewpoint of the required performance, the polymer constituting the core part and the polymer constituting the shell part are the types of structural units (types of monomers as raw materials) and / or the weight ratio of structural units (weight ratio of monomers). ) Is different. That is, the polymer in the core part improves glossiness and printing density, and the polymer in the shell part has a function of stability as an aqueous dispersion of the core-shell polymer particles (B).
The core part or the shell part of the core-shell polymer particle (B) does not necessarily need to be cross-linked, but the core part or the shell part is cross-linked from the viewpoint of improving the printing density and gloss and suppressing the bronze phenomenon. It is preferable that it is the crosslinked polymer particle (C) which becomes.
Among the crosslinked polymer particles (C), crosslinked core-shell polymer particles in which both the core part and the shell part are crosslinked are particularly preferable from the viewpoints of improving the printing density and gloss and suppressing the bronze phenomenon.
When the core part of the core-shell polymer particle (B) is an uncrosslinked polymer, it is preferably a polymer obtained by polymerizing a hydrophobic monomer.
When the core part of the core-shell polymer particle (B) is a crosslinked polymer, the polymer is obtained by polymerizing a crosslinkable monomer and a hydrophobic monomer having at least two reactive unsaturated groups in the molecule. Is preferred.

Examples of hydrophobic monomers that can be used include alkyl (meth) acrylates and aromatic group-containing monomers. Specific examples thereof include hydrophobic monomers described in the water-insoluble polymer column. Among these, styrene monomers such as styrene and 2-methylstyrene, and aromatic group-containing (meth) acrylates such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are particularly preferable.
Examples of the crosslinkable monomer having at least two reactive unsaturated groups in the molecule (hereinafter, also simply referred to as “crosslinkable monomer”) include (1) ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,2-butylene glycol di (meth) acrylate, 1,3-butylene Glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythrito (Meth) acrylic acid ester compounds of polyhydric alcohols such as rutetra (meth) acrylate; (2) acrylamides such as N-methylallylacrylamide, N-vinylacrylamide, N, N′-methylenebis (meth) acrylamide, bisacrylamide acetic acid Compound: (3) Divinyl compound such as divinylbenzene, divinyl ether, divinylethyleneurea, etc .; (4) diallyl phthalate, diallyl malate, diallylamine, triallylamine, triallyl ammonium salt, allyl etherified pentaerythritol, in the molecule And polyallyl compounds such as allyl ethers of sucrose having at least two allyl ether units.
Among these, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, divinylbenzene, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, and methylenebisacrylamide are particularly preferable.

On the other hand, from the viewpoint of improving the printing density and glossiness and suppressing the bronze phenomenon, the structural unit constituting the shell portion of the core-shell polymer particle (B) and the structural unit constituting the crosslinked polymer (A) are the above-mentioned water. A monomer species selected from the group consisting of (a) a salt-forming group-containing monomer, (b) a macromer, (c) a hydrophobic monomer, (d) a hydroxyl group-containing monomer, and (e) a component described in the insoluble polymer column. It is preferable to include structural units derived from two or more same monomer species, more preferably to include structural units derived from three or more same monomer species, derived from five monomer types (a) to (e) It is particularly preferable that the structural unit is included. That is, two or three or more monomers selected from the monomer group constituting the shell portion of the core-shell polymer particle (B) and two or three or more monomers selected from the monomer group constituting the crosslinked polymer (A). Is the same.
Particularly preferably, the structural unit constituting the shell portion of the core-shell polymer particle (B) and the structural unit constituting the crosslinked polymer (A) preferably have two or more identical structural units, and three or more identical structural units. It is more preferable that all have the same structural unit.
When the shell part of the core-shell polymer particle (B) is an uncrosslinked polymer, a monomer mixture containing (a) a salt-forming group-containing monomer, (b) a macromer and / or (c) a hydrophobic monomer is copolymerized. It is preferable to use a polymer.
When the shell part of the core-shell polymer particle (B) is a crosslinked polymer, a monomer mixture containing (a) a salt-forming group-containing monomer, (b) a macromer and / or (c) a hydrophobic monomer is copolymerized. It is preferable that the resulting polymer is a polymer obtained by crosslinking with a crosslinking agent.

The crosslinked polymer particle (C) is obtained by crosslinking polymer particles obtained by copolymerizing a monomer mixture containing (a) a salt-forming group-containing monomer, (b) a macromer and / or (c) a hydrophobic monomer, with a crosslinking agent. Polymer particles obtained (polymer particles obtained by the same production method as the crosslinked polymer particles (A) except that no colorant is contained), or (a) a salt-forming group-containing monomer, (b) a macromer and / or (c ) Polymer particles obtained by copolymerizing a monomer mixture containing a hydrophobic monomer and a crosslinkable monomer can be used. Here, (a) the salt-forming group-containing monomer, (b) the macromer, and (c) the hydrophobic monomer are as described above.
From the viewpoint of improving the printing density and gloss, and suppressing the bronze phenomenon, the structural unit constituting the crosslinked polymer particle (C) and the structural unit constituting the crosslinked polymer (A) are described in the water-insoluble polymer column. A monomer species selected from the group consisting of (a) a salt-forming group-containing monomer, (b) a macromer, (c) a hydrophobic monomer, (d) a hydroxyl group-containing monomer, and (e) a component, It is preferable to include a structural unit derived from a monomer species, more preferably include a structural unit derived from three or more same monomer species, and include a structural unit derived from five monomer types (a) to (e). It is particularly preferred. That is, two or three or more monomers selected from the monomer group constituting the crosslinked polymer particle (C) and the two or three or more monomers selected from the monomer group constituting the crosslinked polymer (A) are the same. Is to do.
Particularly preferably, the structural unit constituting the crosslinked polymer particle (C) and the structural unit constituting the crosslinked polymer (A) preferably have two or more identical structural units, and preferably have three or more identical structural units. Are more preferable, and it is particularly preferable that they are all the same structural unit.
Moreover, as a crosslinking agent, the crosslinking agent which has 1 or more groups chosen from the group which consists of 2 or more reactive functional groups in a molecule | numerator, especially a hydroxyl group, an epoxy group, an aldehyde group, and a carboxy group is mentioned preferably. Specific examples thereof are as described in the above-mentioned cross-linking agent column. Among these, compounds having two or more epoxy groups in the molecule, for example, polyglycidyl ethers such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin triglycidyl ether, and polyglycerol polyglycidyl ether are particularly preferable.

  The polymer constituting the core part and the shell part of the core-shell polymer particles (B) is obtained by copolymerizing the 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. Can be manufactured. As a method for producing the core-shell polymer particles (B), a known method such as seed polymerization or dispersion polymerization can be used.

Moreover, it is preferable to manufacture the bridge | crosslinking core-shell polymer particle by which both a core part and a shell part are bridge | crosslinked by the method which has the following processes 1-3.
Step 1: A water-insoluble polymer, a crosslinkable monomer having at least two reactive unsaturated groups in the molecule, an organic solvent, a hydrophobic monomer, and an emulsion composition containing water are obtained. Step 2: Obtained in Step 1 Step 3: Obtaining a dispersion of core-shell polymer particles obtained by polymerizing the hydrophobic monomer and the crosslinkable monomer in the obtained emulsified composition to crosslink the core portion. The core portion obtained in Step 2 is crosslinked. Reacting the formed core-shell polymer particles with a crosslinking agent having at least two reactive functional groups in the molecule

In step 1, a water-insoluble polymer is first dissolved in an organic solvent, and then a crosslinkable monomer having at least two reactive unsaturated groups in the molecule, a hydrophobic monomer, water, and, if necessary, a neutralizing agent A method of obtaining an emulsified composition by adding a surfactant or the like and mixing them is preferred. In the emulsified composition, the organic solvent is preferably 5 to 60% by weight, more preferably 5 to 40% by weight, and the water-insoluble polymer having a salt-forming group is preferably 1 to 30% by weight, and more preferably 3 to 20% by weight. Preferably, the hydrophobic monomer is preferably 1 to 30% by weight, more preferably 2 to 20% by weight, the crosslinkable monomer is preferably 10 to 70% by weight, more preferably 20 to 70% by weight, and water is 30% by weight. -90 weight% is preferable and 40-85 weight% is still more preferable. Preferred examples of the water-insoluble polymer and the organic solvent include those described above.
There is no particular limitation on the degree of neutralization when the water-insoluble polymer has a salt-forming group. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5-10. Further, a water-insoluble polymer having a salt-forming group may be neutralized in advance. Examples of the neutralizing agent include those described above.
Although there is no restriction | limiting in particular in the emulsification method in the process 1, It is preferable to fully emulsify a monomer mixture by the ultrasonic dispersion method etc. The ultrasonic disperser preferably has a frequency of 20 to 2000 kHz and a wattage per liter of the total reaction liquid amount of preferably 20 to 1000 W, more preferably 50 to 800 W. It is commercially available from companies such as Nippon Seiki Seisakusho and Alex. The emulsification conditions in step 1 are preferably 5 to 50 ° C., and preferably about 0.5 to 3 hours.
The use amount of the crosslinkable monomer having at least two reactive unsaturated groups in the molecule is based on 100 parts by weight of the total of the hydrophobic monomer and the crosslinkable monomer from the viewpoint of printing density, glossiness and bronzing phenomenon suppression. 0.5 to 20 parts by weight is preferable, 0.7 to 15 parts by weight is more preferable, 1 to 10 parts by weight is further preferable, and 1 to 8 parts by weight is particularly preferable.

In Step 2, a dispersion of core-shell polymer particles in which the core portion is crosslinked by polymerizing the hydrophobic monomer and the crosslinkable monomer in the obtained emulsion composition can be obtained. The core-shell polymer particles obtained in Step 2 have a core part formed by crosslinking a polymer having a structural unit derived from a hydrophobic monomer, and a shell part made of a water-insoluble polymer having a salt-forming group.
In step 3, the obtained core-shell polymer particles obtained by crosslinking the core part are reacted with a crosslinking agent having at least two reactive functional groups in the molecule to obtain crosslinked core-shell polymer particles. In this step 3, the water-insoluble polymer as the shell part is crosslinked to obtain crosslinked core-shell polymer particles in which both the core part and the shell part are crosslinked.
The catalyst, solvent, temperature, and time in the above reaction can be appropriately determined in consideration of the crosslinking agent to be used. The reaction time is preferably 0.5 to 10 hours, more preferably 1 to 5 hours, and the reaction temperature is preferably 40 to 95 ° C.
The amount of the crosslinking agent used is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the water-insoluble polymer (shell part polymer), from the viewpoint of improving the printing density, glossiness and suppressing the bronze phenomenon. 3-8 weight part is more preferable, and 0.5-6 weight part is still more preferable.

In the core-shell polymer particle (B), the crosslinking degree of the core part represented by the following formula (6) is preferably 0.5 to 20% by weight, more preferably 0.7 to 0.7% from the viewpoint of printing density and gloss. It is 15% by weight, more preferably 1 to 10% by weight, and particularly preferably 1 to 8% by weight.
Cross-linking degree of core part (% by weight) = (Amount of cross-linking agent / Amount of polymer of cross-linking core part) × 100 (6)
In Formula (6), the polymer amount of the crosslinked core portion is the amount of crosslinked polymer, and includes a crosslinking agent.
Moreover, the crosslinking degree of the shell part represented by the following formula (7) is preferably 0.1 to 15 parts by weight, more preferably 0.3 to 10 parts by weight, from the viewpoint of printing density and gloss. 0.5-8 parts by weight is more preferable, 1-7.5 parts by weight is still more preferable, 1-6.5 parts by weight is particularly preferable, and 1.5-6 parts by weight is most preferable.
Cross-linking degree of shell part (% by weight) = (Amount of cross-linking agent / Amount of polymer of shell part) × 100 (7)
In Formula (7), the polymer amount of the shell portion is the amount of polymer before crosslinking, and does not include the amount of crosslinking agent.
Here, the crosslinking ratio (mol%) of the shell portion determined by the following formula (8) is preferably 1 to 80%, more preferably 3 to 60%, and particularly preferably, from the viewpoint of printing density and gloss. Is 5 to 50%.
Crosslinking rate (mol%) = [number of mole equivalents of crosslinking agent to be reacted with 1 mole of polymer constituting the shell portion × 100 / number of moles of reactive group capable of reacting with the crosslinking agent possessed by 1 mole of polymer constituting the shell portion] (8)
In the formula (8), “the number of molar equivalents of the crosslinking agent reacted with 1 mol of the polymer constituting the shell part” means the number of moles of the crosslinking agent reacted with 1 mol of the polymer constituting the shell part in one molecule of the crosslinking agent. It is a value multiplied by the number of reactive groups.
Moreover, the crosslinking degree of the crosslinked polymer particles (C) represented by the following formula (9) is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, from the viewpoint of printing density and gloss. More preferably, it is 1-10 weight%, Most preferably, it is 2-8 weight%.
Crosslinking degree of crosslinked polymer particles (C) (% by weight) = (amount of crosslinking agent / amount of crosslinked polymer) × 100 (9)
In the formula (9), the amount of the crosslinked polymer is the amount of the crosslinked polymer, and in the case of the core-shell polymer, the total amount of the polymer amount of the crosslinked core portion and the polymer amount of the crosslinked shell portion.

(Colorant-containing crosslinked polymer particles (A), and core-shell polymer particles (B) or aqueous dispersions containing crosslinked polymer particles (C), and water-based ink)
The aqueous dispersion of the present invention is obtained by mixing the colorant-containing crosslinked polymer particles (A) and the core-shell polymer particles (B) or the crosslinked polymer particles (C) obtained by the above-described method, and if necessary, water-insoluble. It can be obtained by the presence of an organic compound.
The water-based ink of the present invention is an ink containing the water dispersion of the present invention and containing water as a main medium. If necessary, additives such as a wetting agent, a dispersant, an antifoaming agent, an antifungal agent, and a chelating agent. Can be added. There is no restriction | limiting in particular in the mixing method of each of these components.

Colorant-containing crosslinked polymer particles (A), core-shell polymer particles (B) or crosslinked polymer particles (C), water-insoluble organic compounds, and water content in the aqueous dispersion for ink jet recording and water-based ink are improved in print density. From the viewpoint of improving the gloss and suppressing the bronze phenomenon, the following is achieved.
The content of the colorant-containing crosslinked polymer particles (A) is preferably 1 to 15% by weight, more preferably 2 to 12% by weight, and particularly preferably 2 to 10% by weight.
The content of the core-shell polymer particles (B) is preferably 0.3 to 10% by weight, more preferably 0.5 to 8% by weight, and particularly preferably 1 to 5% by weight.
The content of the crosslinked polymer particles (C) is preferably 0.3 to 10% by weight, more preferably 0.5 to 8% by weight, and particularly preferably 1 to 5% by weight.
The weight ratio of the core part to the shell part (core part / shell part) is preferably 0.3 to 15, more preferably 0.4 to 13, still more preferably 0.5 to 10, Especially preferably, it is 0.5-8. In the case of crosslinking, the calculation of the weight ratio between the core part and the shell part includes the amount of the crosslinking agent.
The content of the water-insoluble organic compound is preferably 0.1 to 5% by weight, more preferably 0.2 to 4% by weight, and particularly preferably 0.3 to 3% by weight.
The water content is preferably 30 to 90% by weight, more preferably 40 to 80% by weight.

The average particle diameter of the colorant-containing crosslinked polymer particles (A) in the obtained water dispersion and water-based ink is preferably 0.01 to 0.5 μm from the viewpoint of improving the printing density, improving the glossiness, and suppressing the bronze phenomenon. More preferably, it is 0.03-0.3 micrometer, Most preferably, it is 0.05-0.2 micrometer.
The average particle size of the core-shell polymer particles (B) and the crosslinked polymer particles (C) is preferably 0.01 to 0.5 μm, more preferably from the viewpoint of improving the printing density, improving the glossiness, and suppressing the bronze phenomenon. Is 0.03 to 0.2 μm, particularly preferably 0.04 to 0.15 μm.
The average particle diameter is determined by the method described in the examples.
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 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 pH of the water-based ink is preferably 4-10.

The water-based ink for ink-jet recording of the present invention can obtain a highly glossy printed matter when printed on special paper. Examples of the special paper include ink jet photographic paper having a void type glossy medium having a 60 ° glossiness of preferably 10 to 45. Here, the glossiness is a value measured by the method described in the examples. Such photographic paper is commercially available, and a preferred example is Seiko Epson Corporation trade name: KA450PSK.
The ink jet method to which the water-based ink of the present invention is applied is not limited, but is particularly suitable for a piezo 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 Examples 1 to 3 (Production of water-insoluble polymer)
In a reaction vessel, 20 parts of methyl ethyl ketone (MEK), 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol) and 10% of 200 parts of each monomer shown in Table 1 are mixed and mixed, and nitrogen gas replacement is sufficiently performed. To obtain a mixed solution.
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 then at 70 ° C. for 2 hours. Furthermore, the solution of the polymer (P1-P3) which adjusted the polymer concentration to 35 weight% with methyl ethyl ketone was obtained.
The weight average molecular weight of the obtained polymer was measured by a gel chromatography using dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent, using polystyrene as a standard substance. The results are shown in Table 1.

The details of the compounds shown in Table 1 are as follows.
43PAPE600B: Phenoxy polyethylene glycol polypropylene glycol monomethacrylate (average number of moles of added ethylene oxide = 6, average number of added moles of propylene oxide = 6), terminal: phenyl group, manufactured by NOF Corporation, trade name: BLEMMER 43PAPE600B
PP-800: Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 13, terminal hydroxyl group), manufactured by NOF Corporation, trade name: BLEMMER PP-800
NM-95: Styrene macromer: Japanese Patent Application Laid-Open No. 2005-54175, Macromer described in Production Example 1, number average molecular weight: 3200, polymerizable functional group: methacryloyloxy group

Preparation Examples 1 to 3 (Preparation of dispersion of water-insoluble crosslinked polymer particles containing colorant)
68 parts of the polymer obtained by drying the polymer solutions obtained in Production Examples 1 to 3 under reduced pressure were dissolved in 281 parts of methyl ethyl ketone, and then 12.4 parts of neutralizer 1 (5N aqueous sodium hydroxide solution) (degree of neutralization) 55%) and neutralizing agent 2 (25% aqueous ammonia solution) 6.5 parts (neutralization degree 100%) and ion-exchanged water 975 parts were added to neutralize the salt-forming groups, and copper phthalocyanine pigment (Pigment Blue) 15: 3) 157 parts were added, and dispersion treatment was performed for 2 hours at a peripheral speed of 15 m / s using a pico mill manufactured by Asada Iron Works Co., Ltd. The obtained mixture was subjected to a 5-pass dispersion treatment at a pressure of 150 MPa with a microfluidizer (trade name, manufactured by Microfluidics).
Methyl ethyl ketone was removed from the obtained dispersion at 60 ° C. under reduced pressure, and a part of water was further removed, and a 5 μm filter (acetylcellulose membrane, outer diameter: 2.5 Dm, manufactured by Fuji Photo Film Co., Ltd.) was used. An aqueous dispersion of pigment-containing water-insoluble polymer particles having a solid content concentration of 22% was obtained by filtering with an attached needleless syringe having a capacity of 25 mL (manufactured by Terumo Corporation) to remove coarse particles.
Next, 200 parts of the obtained water dispersion (13.2 parts of water-insoluble polymer) was put into a reaction vessel under a nitrogen atmosphere, and further a crosslinking agent (Denacol EX-321: Epoxy equivalent 140: Nagase ChemteX Corporation) 0.40 part (crosslinking ratio: 14 mol%) and 47.4 parts of ion exchange water were added, and the reaction was carried out at 90 ° C. for 1.5 hours with stirring, and the concentration was adjusted with ion exchange water. An aqueous dispersion (S1 to S3) of water-insoluble crosslinked polymer particles containing a pigment having a solid content concentration of 20% was obtained.
The average particle size of the aqueous dispersion (S1) was 78 nm, the average particle size of the aqueous dispersion (S2) was 74 nm, and the average particle size of the aqueous dispersion (S3) was 69 nm.

The average particle diameter was measured and the crosslinking rate was calculated as follows.
(1) Average particle diameter It measured with the laser particle analysis system ELS-8000 (cumulant analysis) of 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 was usually about 5 × 10 ⁻³ wt%.
(2) Calculation of crosslinking rate Based on said Formula (5), it computed as follows.
The number of molar equivalents of the crosslinking agent to be reacted with 1 mol of the water-insoluble polymer (weight average molecular weight 160,000) is (0.40 / 140) / (13.2 / 16000) = 34.6.
Here, since the crosslinking agent (Denacol EX-321) reacts with a carboxy group and a hydroxyl group, the number of moles of the reactive group that can react with the crosslinking agent possessed by 1 mole of the water-insoluble polymer is methacrylic acid possessed by 1 mole of the water-insoluble polymer. It is the total number of moles of acid (molecular weight 86) and polypropylene glycol monomethacrylate (PP-800, molecular weight 840).
160000 × 0.12 / 86 + 16000 × 0.15 / 840 = 252 mol Therefore, the crosslinking rate of the water-insoluble polymer is 34.6 × 100/252 = 14 mol%.

Example 1 (Production of core-shell polymer particles a)
84.43 parts of Liquid A (sodium hydroxide 0.1% ion-exchanged water) was put into the reaction vessel, and the mixture was stirred (about 100 rpm) at room temperature with a styrene solution [styrene, divinylbenzene (100 parts of styrene). 6.4 parts, pure content of divinylbenzene is 81% by weight Product name: DVB-810: manufactured by Nippon Steel Chemical Co., Ltd.), 2,2′-azobis (2,4-dimethylvaleronitrile) (polymerization) Initiator V-65, 2.2 parts with respect to 100 parts of styrene)] 10.9 parts) and B liquid obtained by mixing 13.34 parts of 35% methyl ethyl ketone solution of water-insoluble polymer P2 obtained in Production Example 2 After 24.24 parts are dropped, the mixture is emulsified by ultrasonic dispersion (Nippon Seiki Seisakusho, Ultrasonic Generater Nissei Model USS-300T, 300 μA) for 1 hour, then heated to 75 ° C. and stirred for 3 hours. The Te polymerization was carried out. Thereafter, the organic solvent was removed, and a crosslinking agent (Denacol EX-321: Epoxy equivalent 140: manufactured by Nagase ChemteX Corporation) was added at a ratio of 4 parts to 100 parts of the water-insoluble polymer. The mixture was stirred for 5 hours to crosslink, then cooled, and adjusted with ion exchange water to obtain an aqueous dispersion of core-shell polymer particles a having a solid content of 10% (crosslinking ratio of the shell portion: 19 mol%). . The results are shown in Tables 2 and 3.

The crosslinking rate of the shell part was calculated as follows based on the formula (8).
In the production of the core-shell polymer particles a, 4.67 parts of the polymer in the shell part was reacted with 0.19 part (epoxy equivalent 140) of the crosslinking agent (Denacol EX-321), so that the water-insoluble polymer (weight average molecular weight 160,000) The number of molar equivalents of the crosslinking agent to be reacted with 1 mole is
(0.19 / 140) / (4.67 / 160000) = 47.
Here, since the crosslinking agent (Denacol EX-321) reacts with a carboxy group and a hydroxyl group, the number of moles of reactive groups that can react with the crosslinking agent possessed by 1 mole of the water-insoluble polymer is methacrylic acid possessed by 1 mole of the water-insoluble polymer. It is the total number of moles of acid (molecular weight 86) and polypropylene glycol monomethacrylate (PP-800, molecular weight 840).
160000 × 0.12 / 86 + 16000 × 0.15 / 840 = 252 mol Therefore, the crosslinking rate of the shell portion is 47 × 100/252 = 19 mol%.
Examples 2 to 5 (Production of core-shell polymer particles b to e)
Except having used the A liquid and B liquid of Table 2, operation similar to Example 1 was performed and the aqueous dispersion of core-shell polymer particle be of 10% of solid content was obtained. The results are shown in Tables 2 and 3.

Example 6 (Preparation of ink)
To 20.6 parts of the aqueous dispersion S1 of pigment-containing water-insoluble crosslinked polymer particles having a solid content concentration of 20% obtained above, 0.3 part of a water-insoluble organic compound was mixed and stirred to give a water-insoluble organic compound [( i) 25 parts of diester of ethylene oxide adduct of phthalic acid and 2-ethylhexyl alcohol (average addition mole number 4, made by Nippon Emulsifier Co., Ltd., trade name: New Coal 1004) and (ii) of trimellitic acid and lauryl alcohol An ethylene oxide adduct (consisting of 75 parts triester with an average addition mole number of 4, manufactured by Nippon Emulsifier Co., Ltd.) was contained in the polymer particles. In this mixed solution, 16 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), 0.3 part of Proxel XL2 (manufactured by Avicia Corporation), Examples 15 parts of the aqueous dispersion of the core-shell polymer particles a having a solid content of 10% obtained in 1 and ion-exchanged water so that the total amount becomes 100 parts, and the resulting liquid mixture is added to a 1.2 μm filter ( The ink was obtained by filtering through a 25 mL needleless syringe equipped with an acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd., and removing coarse particles.

Examples 7 to 12 (Preparation of ink)
Except that the water dispersions S2 to S3 of pigment-containing water-insoluble crosslinked polymer particles shown in Table 3 and the core-shell polymer particles a to e were blended in the amounts shown in Table 4, the same procedure as in Example 6 was performed.
Comparative Example 1 (Preparation of ink)
In Example 6, it carried out like Example 6 except having changed the part to water, without using the water dispersion of a core shell polymer particle.

The water-based inks obtained in Examples 6 to 12 and Comparative Example 1 were evaluated by performing the following glossiness test and bronze test. The results are shown in Table 4.
(1) Glossiness test Using a commercially available inkjet printer [Seiko Epson Corporation, model number: PX-A650, piezo method], solid printing on commercially available special paper [photo paper <glossy>, manufactured by Seiko Epson Corporation]] [Printing condition = paper type: EPSON photographic paper, print quality: photo, color setting: no color correction] After leaving at 25 ° C. for 24 hours, a glossiness of 20 ° (manufactured by Nippon Denshoku Industries Co., Ltd.) The product name: HANDY GLOSSMETER PG-1) was measured five times, and the average value was obtained. The higher the value, the higher the glossiness.
(2) Bronze test Solid printing was performed under the same conditions as in (1) above, and after standing at 25 ° C for 24 hours, the bronze obtained was visually evaluated by the following method.
◯: Most preferable because red is hardly recognized even in solid printing.
(Triangle | delta): Even if it prints a photograph etc., redness is hard to be recognized.
X: The fluorescent light reflected on the printing surface and the reflected light of sunlight appear reddish.
(3) Printing density Using the printer, solid printing (printing condition = paper type: plain paper, mode setting: super fine) on commercially available plain paper (XEROX, trade name: 4024) at 25 ° C. After being left for 24 hours, the print density was measured 5 times with a Macbeth densitometer (manufactured by Gretag Macbeth, product number: RD914), and an average value was obtained. The higher the value, the higher the print density.

  From Table 4, it can be seen that the water-based inks of Examples 6 to 12 are superior to the water-based ink of Comparative Example 1 in print density, glossiness, bronze suppression, and balance thereof.

Claims (8)

An aqueous dispersion for ink-jet recording comprising water-insoluble crosslinked polymer particles (A) containing pigment and core-shell polymer particles (B) not containing pigment, wherein the core and shell portions of the core-shell polymer particles (B) are crosslinked The structural unit constituting the water-insoluble crosslinked polymer and the structural unit constituting the shell portion of the core-shell polymer particle (B) are (a) a salt-forming group-containing monomer, (b) a macromer, and (c) hydrophobicity. monomers, and monomer species to form a shell portion (d) derived from a monomer species selected from the group consisting of monomers represented by the hydroxyl group-containing monomer, and (e) the following formula (2), the core-shell polymer particles (B) An aqueous dispersion for inkjet recording, wherein the monomer species forming the water-insoluble crosslinked polymer are the same .
CH ₂ = C (R ¹ ) COO (R ² O) _q R ³ (2)
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 or a phenyl group optionally having an alkyl group having 1 to 9 carbon atoms, q means the average number of moles added. , Indicates a number from 1 to 60.)   The aqueous dispersion for inkjet recording according to claim 1, wherein a weight ratio (core part / shell part) of the core part to the shell part of the core-shell polymer particles (B) is 0.3 to 15.   The aqueous dispersion for inkjet recording according to claim 1 or 2, wherein the degree of cross-linking of the shell portion of the core-shell polymer particles (B) is 0.1 to 15% by weight.   The aqueous dispersion for inkjet recording according to any one of claims 1 to 3, wherein the core part of the core-shell polymer particles (B) has a crosslinking degree of 0.5 to 20% by weight.   The core part of the core-shell polymer particle (B) is a polymer obtained by polymerizing a crosslinkable monomer having at least two reactive unsaturated groups in the molecule and a hydrophobic monomer. An aqueous dispersion for inkjet recording as described in 1.   The shell part of the core-shell polymer particle (B) has a polymer obtained by copolymerizing a monomer mixture containing (a) a salt-forming group-containing monomer, (b) a macromer and / or (c) a hydrophobic monomer. The aqueous dispersion for inkjet recording according to any one of claims 1 to 5, which is a polymer obtained by crosslinking with a crosslinking agent having a reactive functional group.   The water dispersion for inkjet recording according to any one of claims 1 to 6, wherein the water-insoluble crosslinked polymer is a polymer obtained by crosslinking 0.1 to 15 parts by weight of a crosslinking agent with respect to 100 parts by weight of the water-insoluble polymer. body.   A water-based ink for inkjet recording, comprising the water dispersion according to any one of claims 1 to 7.