JP2009155569A - Method for producing aqueous dispersion for ink jet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a water-dispersion for inkjet recording excellent in a delivery property, and a water-based ink for inkjet recording containing the water-dispersion. <P>SOLUTION: [1] In the manufacturing method for the water-dispersion for inkjet recording, the water-dispersion containing a coloring agent, a polymer particle, a specific water-insoluble organic compound having the maximum weight capable of being dissolved in 100 g of water (20°C) of 5 g or less, and water is subjected to heat-treatment at 40°C or higher. [2] The water-based ink for inkjet recording contains the obtained water-dispersion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an aqueous dispersion for inkjet recording, and an aqueous ink for inkjet recording containing the aqueous dispersion.

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 matter, those using pigment-based ink as a colorant have become mainstream. (For example, see Patent Documents 1 to 3)
In Patent Document 1, a mixture containing water, a colorant, a water-insoluble polymer, and an organic solvent is dispersed in order to provide a water-based ink for ink-jet recording with little change in viscosity after ink production and excellent storage stability. Then, the organic solvent is removed to obtain a water dispersion of water-insoluble polymer particles containing a colorant (1), and the water dispersion is heated at 40 ° C. or higher (2). A method for producing a water-based ink for inkjet recording is disclosed.
Patent Document 2 discloses a step of obtaining a mixture containing a water-insoluble polymer, an organic solvent, a colorant, and water in order to provide a water-based ink for ink-jet recording having high printing density and excellent glossiness and image clarity ( 1) a step (2) of dispersing the obtained mixture, and a step (3) of removing the organic solvent from the obtained dispersion to obtain an aqueous dispersion of water-insoluble polymer particles containing a colorant. And a method for producing an aqueous dispersion for inkjet recording in which a water-insoluble organic compound is present during or after any of the steps.
Patent Document 3 discloses a step of mixing a water-insoluble polymer, a pigment, an organic solvent, and water to disperse the water-insoluble organic compound stably in the water-insoluble polymer particles, thereby obtaining a pigment dispersion. A method for producing a pigment dispersion containing a water-insoluble organic compound, which comprises a step of mixing and dispersing the obtained dispersion and a water-insoluble organic compound, is described.
However, the above-described pigment dispersion is not satisfactory in terms of dischargeability.

JP 2006-01971 A Japanese Patent Application Laid-Open No. 2007-077375 JP 2007-131817 A

  It is an object of the present invention to provide a method for producing an aqueous dispersion for inkjet recording excellent in dischargeability, and an aqueous ink for inkjet recording containing the aqueous dispersion.

The present inventors have found that the dischargeability can be improved by heat-treating the pigment aqueous dispersion containing the polymer particles and the water-insoluble organic compound.
That is, the present invention provides the following [1] to [2].
[1] Water that has a maximum weight of 5 g or less that can be dissolved in 100 g (20 ° C.) of a colorant, polymer particles, and water, and is at least one selected from the group consisting of ester compounds, ether compounds, and sulfonic acid amide compounds. A method for producing an aqueous dispersion for inkjet recording, comprising a step of heat-treating a mixture containing an insoluble organic compound and water at 40 ° C. or higher.
[2] A water-based ink for inkjet recording, comprising the aqueous dispersion for inkjet recording obtained by the method of [1].

  The aqueous ink for inkjet recording containing the aqueous dispersion obtained by the production method of the present invention is excellent in ejectability.

  According to the method for producing an aqueous dispersion for ink-jet recording of the present invention, by heating the polymer particles in the presence of the water-insoluble organic compound, the water-insoluble organic compound incorporated in the polymer particles is converted into a polymer composition of the polymer particles. Since the formation of the polymer particles is changed and the polymer particles become more stable, it is considered that the discharge from the nozzle is excellent when the water-based ink is used. Hereafter, each component etc. which are used for this invention are demonstrated.

(Water-insoluble organic compound)
In the present invention, the maximum weight that can be dissolved in 100 g (20 ° C.) of water is 5 g or less, and one or more water-insoluble organic compounds selected from the group consisting of ester compounds, ether compounds, aromatic alcohols, and sulfonic acid amide compounds (Hereinafter, also simply referred to as “water-insoluble organic compound”). The water-insoluble organic compound used in the present invention is considered to have a function of improving the mobility by containing at least a part thereof in polymer particles. Therefore, it is considered that the heat treatment in the presence of the water-insoluble organic compound further improves the mobility of the polymer particles and makes the dispersion more stable.

The water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, and more preferably has a molecular weight of 100 to 1,000, from the viewpoint of improving ejection properties.
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 preferably has a LogP value of −1 to 11, more preferably 1 to 9, still more preferably 1.5 to 8, and particularly preferably 2 to 7. preferable.
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] − [Log P value of the polymer]] is preferably −4 to 8, It is more preferably 2 to 6, 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. 84: 83-92 .). 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.

Moreover, 7-12 are preferable and, as for SP value of a water-insoluble organic compound, 9-11 are more preferable.
The SP value (solubility parameter) is a numerical value indicating the magnitude of polarity per unit volume, which is the aggregation energy density, that is, a value obtained by multiplying the evaporation energy per unit volume of one molecule by 1/2. The value can be calculated by the method of Fedors [Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)].

The water-insoluble organic compound is preferably at least one selected from the group consisting of an ester compound, an ether compound, an aromatic alcohol, and a sulfonic acid amide compound in order to facilitate inclusion in the polymer particles, and (f) in the molecule, An ester or ether compound having two or more ester or ether bonds, (g) one or more ester or ether bonds in the molecule, a carboxy group, a sulfuric acid group, a sulfonic acid group, a phosphonic acid group, a phosphoric acid residue More preferred are esters or ether compounds and / or (h) aromatic alcohols having at least one functional group selected from the group consisting of carbonyl group, epoxy group and hydroxyl group.
(F) The ester or ether bond of the compound is preferably 2 to 3, and may have an ester bond and an ether bond. (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. A phosphoric acid residue means the remaining phosphoric acid group in which a part of phosphoric acid was esterified.
Among the ester compounds, an ester obtained from a monovalent carboxylic acid or a salt thereof and a polyhydric alcohol, an ester obtained from a polyvalent acid (polyvalent carboxylic acid, phosphoric acid) or a salt thereof and a monohydric alcohol is preferred, and aliphatic. Or it is more preferable to have two 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. Of the ether compounds, polyhydric alcohol ethers are preferred.

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, , Benzoic acid).
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.
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). And an aromatic alcohol having 6 to 12 carbon atoms (for example, phenol).
Examples of the polyhydric alcohol include C2-C12 polyhydric alcohols such as ethylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and glycerin.
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, (4) phosphoric 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) Aromatic alcohol and the like can be mentioned.
Among these, from the viewpoint of dischargeability, the compounds of (1) to (5), (8) and (10) are preferable, (1) aliphatic di- or tricarboxylic acid ester, (2) aromatic carboxylic acid. More preferably, it is at least one selected from the group consisting of an ester, (3) a cycloalkane (ken) carboxylic acid ester, and (4) a phosphoric acid ester, (1) an aliphatic dicarboxylic acid ester, (2) an aromatic Particularly preferred is one or more selected from the group consisting of di- or tricarboxylic acid esters, (3) cycloalkane (ken) dicarboxylic acid esters, and (4) phosphoric acid esters.
(1) Aliphatic dicarboxylic acid ester, (2) aromatic dicarboxylic acid ester, and (3) cycloalkane (ken) dicarboxylic acid ester are preferably compounds represented by the following formula (1).

(.R wherein, R ¹ and R ² are each independently a hydrogen atom, or a hydrocarbon group having 1 to 22 carbon atoms, R ³ is showing a divalent hydrocarbon group having 1 to 18 carbon atoms ¹ and R ² may be the same or different, except when R ¹ and R ² are both hydrogen atoms, R ^{1 to} R ³ may have a substituent, and m and n are Each independently represents an average addition mole number of 0 to 30, and AO represents an alkanediyloxy group.)

R ¹ and R ² are preferably 2 to 18 carbon atoms, more preferably a linear or branched alkyl group or alkenyl group having 4 to 12 carbon atoms, 7 to 23 carbon atoms, from the viewpoint of improving ejection properties. Preferably, it is an aralkyl group having 7 to 11 carbon atoms, or an aryl group having 6 to 22 carbon atoms, preferably 6 to 10 carbon atoms. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group Hexyl group, 2-ethylhexyl group, octyl group, dodecyl group, cetyl group, phenyl group, benzyl group and the like. The same applies to the following equations.
R ³ is preferably a divalent aliphatic hydrocarbon group, a cyclic hydrocarbon group or an aromatic hydrocarbon group, preferably 2 to 15 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 carbon atoms. An alkanediyl group (alkylene group) or an alkenylene group having 8 to 8 carbon atoms, an arylene group having 6 to 10 carbon atoms, more preferably a phenylene group, or a cyclic saturated or unsaturated hydrocarbon group having 3 to 8 carbon atoms. Specifically, ethylene group, trimethylene group, propane-1,2-diyl group, tetramethylene group, heptamethylene group, hexamethylene group, pentane-1,5-diyl group, octamethylene group, dodecamethylene group, phenylene Groups and the like. The same applies to the following equations.
m and n are each independently preferably 0 to 20, more preferably 0 to 15, still more preferably 1 to 15, particularly preferably 2 to 14, and most preferably 2 to 12.

AO is the number of carbon atoms such as ethyleneoxy group (EO), propyleneoxy group (trimethyleneoxy group or propane-1,2-diyloxy group) (PO), butyleneoxy group (tetramethyleneoxy group etc.) (BO), etc. 2 to 4 alkanediyloxy groups (alkyleneoxy groups), and when m and n are 2 or more, AO may be the same or different, and when they are different, AO may be added in blocks or randomly. It may be.
Examples of the substituent that R ^{1 to} R ³ may have include halogen atoms such as fluorine, chlorine and bromine atoms, alkoxy groups having 1 to 12 carbon atoms such as methoxy, ethoxy and isopropoxy groups, phenyloxy Aryloxy groups such as oxycarbonyl groups such as methoxycarbonyl groups, acyl groups such as acetyl and benzoyl groups, acyloxy groups such as acetyloxy groups, cyano groups, nitro groups, hydroxyl groups, carboxy groups, oxo groups, epoxy groups , Ether groups, ester groups and the like (these are collectively referred to as “substituents”). These substituents may be one or a combination of two or more.
The substituent that R ³ may have is preferably —CO (O) — (AO) _L —R ⁴ . In the formula, AO is the same as described above. L has the same meaning as m described above, and the preferred range is also the same. R ⁴ has the same meaning as R ¹ described above, and the preferred range is also the same. In this case, R ³ is preferably an aromatic hydrocarbon group.

(1) The aliphatic carboxylic acid ester is more specifically a compound in which, in the formula (1), R ³ is a divalent aliphatic hydrocarbon group which may have a substituent. preferable. Examples of this substituent include the above-described substituents.
Specific examples of the aliphatic carboxylic 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, diethyl sebacate Examples thereof include aliphatic dibasic acid esters such as keto, 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 ¹ and R ² are both 2-ethylhexyl and EO average added moles m and n, respectively) = 1 to 4), bis (octoxypolypropylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, average added moles of PO and n = 1 to 6), bis (octoxypolyethyleneglycol / polypropylene) Propylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, EO and PO total average addition moles m and n = 4-12, block addition), bis [octoxypoly (ethylene glycol propylene glycol)] adipate (R ¹ and R ² are both 2 -Ethylhexyl, EO and PO total average addition moles m and n = 4-12, random addition), diethyl sebacate, dibutyl sebacate, diisobutyl sebacate, etc. Diesters are particularly preferred.

  (2) More specifically, the aromatic carboxylic acid ester is more preferably a compound represented by the following formula (2).

(In the formula, R ¹ and R ² have the same meaning as described above, and may be the same or different. AO, m and n have the same meaning as described above, and m and n are 2 or more. AO may be the same or different.)
Specific examples of aromatic carboxylic acid esters include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, bis (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, octyl benzyl phthalate, nonyl Phthalic acid esters such as benzyl phthalate, stearyl benzyl phthalate, octyl decyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, bis (dimethylcyclohexyl) phthalate, bis (t-butylcyclohexyl) phthalate, ethyl phthalyl ethyl glycolate, tributyl trimellitate, Trimellitic acid esters such as triisobutyl trimellitate and tri (2-ethylhexyl) trimellitate It is below. Among these, 3 carbon atoms such as phthalic acid diester having an aliphatic alcohol residue having 1 to 5 carbon atoms such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, octyl benzyl phthalate, nonyl benzyl phthalate, stearyl benzyl phthalate Benzyl phthalate having -18 alkyl groups, bis (octoxypolyethylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, average addition number m of EO and n = 1-5), bis (octoxy Polypropylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, average added moles m and n of PO = 1 to 4), bis (octoxypolyethylene glycol / polypropylene glycol) phthalate (R ¹ and R ² Are both 2-Echi Hexyl, each total average addition mole number m and n = 4 to 12 of EO and PO, block addition), bis [Okutokishipori (ethylene glycol-propylene glycol) phthalate (R ¹ and R ² are both 2-ethylhexyl, EO and The total average number of moles of PO added m and n = 4 to 12, random addition) and the like, and phthalic acid esters such as tributyl trimellitate and triisobutyl trimellitate, The trimellitic acid diester is particularly preferred.

(3) More specifically, the cycloalkane (ken) carboxylic acid ester is more preferably a cyclohexane (cene) carboxylic acid ester represented by the following formula (3). Examples of the cycloalkane (ken) group include a cyclic hydrocarbon group which may have one unsaturated group having 3 to 8 carbon atoms.

(In the formula, R ¹ and R ² have the same meaning as described above, and may be the same or different. AO, m and n have the same meaning as described above, and m and n are 2 or more. AO may be the same or different.)
Specific examples of the cycloalkane (ken) carboxylic acid ester include cyclohexane carboxylic acid esters such as 1,2-cyclohexanedicarboxylic acid dibutyl ester, 1,2-cyclohexanedicarboxylic acid diisononyl ester, and 3,4-cyclohexene dicarboxylic acid dibutyl ester. And cyclohexene carboxylic acid esters such as 3,4-cyclohexene carboxylic acid diisononyl ester.
(4) The phosphate ester is preferably a compound represented by the following formula (4).

(In the formula, R ¹ and R ² have the same meaning as described above and may be the same or different.)
Specific examples of phosphate esters include tributyl phosphate, tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl A phosphate etc. are mentioned. 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.

(5) Preferable examples of the oxyester include triethyl acetylcitrate, tributyl acetylcitrate, methyl acetylricinoleate and the like.
(6) Preferable examples of glycol esters include diethylene glycol dibenzoate and triethylene glycol di (2-ethylhexoate).
(7) Preferable examples of the epoxy ester include butyl epoxy stearate and octyl epoxy stearate.
(8) Preferable examples of the sulfonamide include o- and p-toluenesulfonamide, N-butylbenzenesulfonamide and the like.
(9) Preferable examples of polyester include poly (1,2-butanediol adipate), poly (1,3-butanediol adipate) and the like.

(10) Examples of glyceryl alkyl ether include monoether, diether, and triether. Among these, linear or branched alkyl having 8 to 30, preferably 8 to 22, and more preferably 8 to 14 carbon atoms. Glyceryl monoethers having a group are preferred. There is no restriction | limiting in particular in the position of an alkyl group.
(11) Examples of glyceryl alkyl esters include monoesters, diesters, and triesters. Among these, linear or branched aliphatic carboxylic acids having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, , Esters of linear aliphatic carboxylic acids such as acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid and palmitic acid, and branched aliphatic carboxylic acids such as pivalic acid). More specifically, glyceryl triacetate, glyceryl diacetate, glyceryl monoacetate and the like can be mentioned.
(12) Examples of glycol alkyl ether include monoether and diether, and examples of glycol include ethylene glycol and neopentyl glycol. Moreover, as an alkyl group, C1-C22, Preferably it is C6-C20, More preferably, a C8-C18 linear or branched alkyl group is mentioned.
(13) The aromatic alcohol is preferably a compound having 6 to 12 carbon atoms, more preferably an aryl group, alkylaryl group, or arylalkyl group having 6 to 10 carbon atoms and a hydroxyl group, and one hydroxyl group. Is preferred. Specific examples include benzyl alcohol, cuminyl alcohol, phenethyl alcohol, hydrocinnamyl alcohol and the like.

[Colorant]
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, storage stability and scratch resistance. Pigments and hydrophobic dyes are preferred.
When the pigment and the hydrophobic dye are used in an aqueous dispersion, it is preferable to use a surfactant and a polymer to form fine particles that are stable in the ink. In particular, from the viewpoint of bleeding resistance, water resistance and the like, it is preferable to include a pigment and / or a hydrophobic dye in the polymer particles. It is preferable to contain a pigment.
The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments (silica, calcium carbonate, talc, etc.), self-dispersing pigments and the like.
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. Carbon black can also be oxidized by a gas phase or liquid phase oxidation method using an oxidizing agent such as ozone, nitric acid, hydrogen peroxide, nitrogen oxide, or a surface modification method such as plasma treatment.
Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, and pyrozolone pigments.
The hue is not particularly limited, and any chromatic pigment such as a red organic pigment, a yellow organic pigment, a blue organic pigment, an orange organic pigment, and a green orange organic pigment can be used.
Preferred examples of organic pigments include C.I. I. Pigment yellow, C.I. I. Pigment Red, C.I. I. Pigment violet, C.I. I. Pigment orange, 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 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.
The above colorants can be used alone or in admixture of two or more at any ratio.

(Polymer particles)
In the present invention, the polymer particles are used to stably disperse the colorant and to improve dischargeability by interaction with the water-insoluble organic compound.
Polymers used for the polymer particles include polyesters, polyurethanes, vinyl polymers, etc. From the viewpoint of dispersion stability, vinyl polymers obtained by addition polymerization of vinyl monomers (vinyl compounds, vinylidene compounds, vinylene compounds). (Hereinafter also simply referred to as “vinyl polymer”) is preferable. Moreover, you may use a crosslinked polymer from a viewpoint of the further improvement of dispersion stability.
The polymer used for the polymer particles is preferably a water-insoluble polymer in order to easily contain a water-insoluble organic compound. 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.

(Vinyl polymer)
The vinyl polymer includes (a) a salt-forming group-containing monomer (hereinafter also referred to as “(a) component”), (b) a macromer (hereinafter also referred to as “(b) component”) and / or (c) a hydrophobic monomer. A water-insoluble vinyl polymer obtained by copolymerizing a monomer mixture (hereinafter also referred to as “component (c)”) (hereinafter also referred to as “monomer mixture”) 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 vinyl polymer has a structural unit derived from component (a), or a structural unit derived from component (a) and a structural unit derived from component (c) in the main chain, and a structural unit derived from component (b). It is a graft polymer in the side chain.

((A) salt-forming group-containing monomer)
(A) The salt-forming group-containing monomer is used from the viewpoint of enhancing the dispersion stability of the resulting polymer particles. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group, and a carboxy group is particularly preferable.
Examples of the salt-forming group-containing monomer include a cationic monomer and an anionic monomer. Examples thereof include those described in paragraph [0022] of JP-A-9-286939.
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-acryloyloxyethyl phosphate, etc. Is mentioned.
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, dischargeability, and the like.

((B) Macromer)
(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. (B) 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 (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.

(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 (5).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _{t -Si (CH 3) 3 (} 5)
(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) hydrophobic monomer)
(C) The hydrophobic monomer is used from the viewpoint of improving the printing density, dispersion stability, dischargeability and the like. 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. A vinyl monomer is preferable, and examples thereof include the styrene monomer and the aromatic group-containing (meth) acrylate. The above-mentioned thing is mentioned as a substituent containing a hetero atom.
Among the components (c), styrene and 2-methylstyrene are particularly preferable as the styrene monomer, and benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, etc. are particularly preferable as the aromatic group-containing (meth) acrylate component. Is preferred.

((D) hydroxyl group-containing monomer)
The monomer mixture may further contain (d) a hydroxyl group-containing monomer (hereinafter also referred to as “component (d)”). (D) The hydroxyl group-containing monomer is used for further improving dispersion stability and ejection properties.
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 (6) (hereinafter also referred to as “component (e)”).
^{_{CH 2 = C (R 7)}} COO (R 8 O) p R 9 (6)
Wherein R ⁷ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ⁸ is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ⁹ 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) is used for further improving the discharge property.
In the formula (6), examples of the hetero atom include a nitrogen atom, an oxygen atom, a halogen atom, and a sulfur atom.
Preferable examples of R ⁷ include a methyl group, an ethyl group, and an (iso) propyl group.
Preferable examples of the R ⁸ 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 having 2 carbon atoms. -7 oxyalkylene groups.
Preferable examples of R ⁹ 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 (6); the same applies hereinafter) (meth) acrylate, methoxypolytetramethylene glycol (1 to 30) ( (Meth) acrylate, ethoxy polyethylene glycol (1-30) (meth) acrylate, octoxy polyethylene glycol (1-30) (meth) acrylate, polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether, (iso) Propoxy polyethylene glycol (1-30) (meth) acrylate, butoxypolyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Polymerization) (1 to 30, ethylene glycol therein: 1-29) (meth) acrylate. Among these, octoxypolyethylene glycol (1-30) (meth) acrylate and polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether are preferable.

Specific examples of commercially available (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.

In the production of the vinyl polymer, the content of the components (a) to (e) in the monomer mixture (content as an unneutralized amount; the same applies hereinafter) or the components (a) to (e) in the water-insoluble polymer The content of the derived structural unit 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 dispersion stability by interaction with the colorant.
The content of the component (c) is preferably 5 to 98% by weight, more preferably 10 to 75% by weight from the viewpoints of print density, dispersion stability, dischargeability, and the like.
The content of the component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight from the viewpoints of dispersion stability and dischargeability of the resulting dispersion.
The content of the component (e) is preferably 5 to 50% by weight, more preferably 7 to 40% by weight, from the viewpoint of dischargeability of the resulting dispersion.
The total content of [(a) component + (d) component] in the monomer mixture is preferably 6 to 60% by weight, more preferably 10 to 50% by weight, from the viewpoint of dispersion stability 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 10 to 50%, from the viewpoint of dispersion stability of the resulting dispersion. % By weight.
Moreover, the weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.01 to 1, more preferably 0.02 from the viewpoints of dispersion stability, dischargeability and the like. It is -0.67, More preferably, it is 0.03-0.50.

(Manufacture of polymers)
The 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, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate. Among these, methanol, ethanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, or a mixed solvent of one or more of these and water are 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 polymer is preferably 5,000 to 500,000, more preferably 10,000 to 400,000, further preferably 10,000 to 300,000, and more preferably 20,000 to 300,000 from the viewpoints of dispersion stability and dischargeability. Particularly preferred. In addition, the weight average molecular weight of the polymer was measured by the method shown in the Examples.
When the polymer has (a) a salt-forming group derived from a salt-forming group-containing monomer, the polymer 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, 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 formula when the salt-forming group is an anionic group.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [acid value of polymer (KOH mg / g) × polymer weight (g) / (56 × 1000)]} × 100
When the salt-forming group is a cationic group, it can be determined by the following formula.
{[Weight of neutralizer (g) / equivalent of neutralizer] / [amine value of polymer (HCL mg / g) × polymer weight (g) / (36.5 × 1000)]} × 100
The acid value and amine value can be calculated from the structural unit of the polymer. Alternatively, it can also be determined by a method in which a polymer is dissolved in an appropriate solvent (for example, methyl ethyl ketone) and titrated. The acid value or amine value of the polymer is preferably 50 to 200, more preferably 50 to 150.

(Method for producing an aqueous dispersion of polymer particles containing a colorant)
In the production method of the present invention, from the viewpoint of dispersion stability, the colorant and the polymer particles are preferably polymer particles containing a colorant in which the colorant is contained in the polymer. Although there is no limitation in particular in the manufacturing method of such an aqueous dispersion, For example, according to the method which has the following process (1) and (2), it can manufacture efficiently.
Step (1): Step of obtaining a dispersion of polymer particles containing a colorant by dispersing a mixture containing a polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent Step (2): Step Step of removing the organic solvent from the dispersion obtained in (1) to obtain an aqueous dispersion of polymer particles containing a colorant In step (1), first, the polymer is dissolved in an organic solvent, and then A method of obtaining an oil-in-water dispersion by adding a colorant, water, and, if necessary, a neutralizing agent, a surfactant and the like to the obtained organic solvent solution and mixing them. 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.
The weight ratio of the colorant amount to the total amount of the polymer and the colorant [colorant / (polymer + colorant)] is preferably 50/100 to 90/100 from the viewpoint of storage stability. / 100 to 85/100 is more preferable.
When the 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 polymer. Examples of the neutralizing agent include those described above. Further, the polymer may be neutralized in advance.

  Examples of the organic solvent include alcohol solvents such as ethanol, isopropanol and isobutanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone, and ether solvents such as dibutyl ether, tetrahydrofuran and dioxane. Preferably, the amount dissolved in 100 g of water at 20 ° C. is preferably 5 g or more, more preferably 10 g or more, more specifically preferably 5 to 80 g, more preferably 10 to 50 g, especially Methyl ethyl ketone and methyl isobutyl ketone are preferred.

There is no restriction | limiting in particular in the dispersion method of the mixture in the said process (1). The average particle size of the polymer particles can be atomized until the desired particle size is obtained without pre-dispersing, but preferably after pre-dispersing with a high-speed stirring mixing device or the like, further dispersion is performed by applying shear stress. It is preferable to control the average particle size of the polymer particles containing the colorant to a desired particle size. 5-50 degreeC is preferable and, as for the dispersion | distribution of a process (1), 5-35 degreeC is still more preferable.
When preliminarily dispersing the mixture, a commonly used mixing and stirring device such as an anchor blade can be used. Among the mixing and stirring apparatuses, high-speed stirring and mixing apparatuses such as Ultra Disper [Asada Tekko Co., Ltd., trade name], Ebara Milder [Ebara Manufacturing Co., Ltd., trade name], TK Homomixer [Primix Co., Ltd., trade name] are preferable. .
Examples of means for applying a shear stress include 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], and Minilab 8.3H type (Rannie Co., trade name). Examples of the high pressure homogenizer include a homovalve type high pressure homogenizer, a chamber type high pressure homogenizer such as a microfluidizer [Microfluidics, trade name], and a nanomizer [Nanomizer, trade name]. A plurality of these devices can be combined.

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. The organic solvent in the aqueous dispersion containing the obtained polymer particles is preferably substantially removed, but may remain as long as the object of the present invention is not impaired. 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 a particle in which the solid content of the polymer containing the colorant is dispersed in water as a main medium. Here, the form of the polymer particles containing the colorant is not particularly limited as long as the particles are formed of at least the colorant and the 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.

Furthermore, from the viewpoint of improving the stability of the dispersion, it is also preferable that the polymer constituting the obtained polymer particles containing the colorant is crosslinked with a crosslinking agent and used as crosslinked polymer particles containing the colorant. As a method for producing a crosslinked polymer particle containing a colorant, a method of obtaining a polymer by crosslinking an aqueous dispersion of a polymer particle containing a colorant and a crosslinking agent is preferable from the viewpoint of ease of production.
As the crosslinking agent, a crosslinking agent having at least two reactive functional groups, specifically, a compound having two or more epoxy groups in the molecule: for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether is used. be able to.
The crosslinking conditions can be appropriately determined in consideration of the type and amount of the crosslinking agent, the type of the catalyst and the solvent, the reaction temperature, the reaction time, etc. The reaction time for crosslinking is preferably 0.5 to The reaction temperature is preferably 40 to 95 ° C. for 10 hours, more preferably 1 to 5 hours.
The amount of the crosslinking agent used is preferably 0.5 to 15 parts by weight, more preferably 0.75 to 10 parts by weight, and 0.8 to 6 parts by weight with respect to 100 parts by weight of the polymer from the viewpoint of dispersion stability. Part by weight is more preferred.

(Method for producing water dispersion for inkjet recording)
The aqueous dispersion for inkjet recording of the present invention has a maximum weight of 5 g or less that can be dissolved in 100 g (20 ° C.) of a colorant, polymer particles, and water, and is selected from the group consisting of an ester compound, an ether compound, and a sulfonic acid amide compound. It is produced by a method having a step of heat-treating a mixture containing one or more selected water-insoluble organic compounds and water at 40 ° C. or higher.

Content of each component in the mixture at the time of heat processing is as follows.
The content of the water-insoluble organic compound is preferably from 0.1 to 10% by weight, more preferably from 0.3 to 5% by weight, and still more preferably from 0.5 to 3% by weight, from the viewpoint of improving dischargeability.
The content of the polymer particles is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and still more preferably 2 to 10% by weight, from the viewpoint of improving dischargeability.
The content of the colorant is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and still more preferably 2 to 10% by weight from the viewpoint of printing density.
The weight ratio of the polymer constituting the polymer particles to the water-insoluble organic compound (water-insoluble organic compound / polymer) is preferably from 1/10 to 2/1, and preferably from 1/10 to 1/1, from the viewpoint of improving dischargeability. Is more preferable.
The mixing operation may be merely stirring using a commonly used mixing stirring device such as the anchor blade described above, but the heat treatment is effectively performed by incorporating the water-insoluble organic compound into the polymer particles. In order to carry out, it is preferable to disperse each component with a disperser that applies a shear stress during mixing. As a dispersion method, for example, a method using a disperser such as the above-described homovalve type high pressure homogenizer such as a roll mill, bead mill, kneader, or extruder, a chamber type high pressure homogenizer, or an ultrasonic homogenizer is preferable.
As the ultrasonic homogenizer, an ultrasonic homogenizer US-300T, US-1200T, RUS-1200T manufactured by Nippon Seiki Seisakusho Co., Ltd., an ultrasonic processor UIP series manufactured by Heelscher, or the like can be used.
The mixture is preferably prepared at 5 to 35 ° C.

The temperature of the heat treatment is preferably 90 ° C. or less, more preferably 50 to 90 ° C., and still more preferably 55 to 75 ° C. from the viewpoints of improving dischargeability and handling properties.
The time for the heat treatment is preferably 30 minutes to 12 hours, more preferably 30 minutes to 9 hours, and still more preferably 1 to 6 hours, from the viewpoint of improving dischargeability and handling properties.
The heat treatment can be performed while the aqueous dispersion is preferably placed in a sealed container and left standing or stirred. By performing the heat treatment at 40 ° C. or higher, the discharge property when using water-based ink is improved.
This is because when the polymer particles are heated to 40 ° C. or higher in the presence of a water-insoluble organic compound, the water-insoluble organic compound incorporated in the polymer particles changes the polymer conformation of the polymer particles, and the polymer particles Since it becomes a more stable state, it is thought that the discharge property from a nozzle becomes favorable. Note that the pressure may be reduced during the heat treatment.
In addition, it is usually preferable that the mixture before the heat treatment does not contain an organic solvent or the like. However, an organic solvent or the like that does not dissolve the polymer particles may be present. That is, the mixture may contain a hydrophilic organic solvent such as monoalkyl ether of alkylene glycol, a preservative, and a wetting agent as long as the object of the present invention is not impaired.
Examples of the alkylene glycol include monoalkylene glycol, dialkylene glycol, and trialkylene glycol. The alkylene group (alkanediyl group) of the alkylene glycol is preferably an alkanediyl group having 2 to 4 carbon atoms, that is, an ethylene group, a propane-1,2-diyl group, a butane-1,3-diyl group, or the like.
The wetting agent is a compound that suppresses the transpiration of water in the aqueous dispersion, and is a polyol compound (including saccharides) having two or more hydroxyl groups. Examples include glycerin, ethylene glycol, diethylene glycol, and 1,3-butanediol.

When the colorant and the polymer particles are polymer particles containing a colorant in which the colorant is contained in the polymer, the polymer particles containing the colorant can be obtained by the above-described production method.
The polymer particles containing the colorant may be cross-linked polymer particles containing the colorant, but from the viewpoint of dispersion stability, it is preferable to use one that has been crosslinked in advance before heating.
In the mixture during the heat treatment, the content of the polymer particles containing the colorant is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, the polymer particles containing the colorant (solid content), and water. The mixing weight ratio with the insoluble organic compound (polymer particles containing a colorant / water-insoluble organic compound) is preferably 30/1 to 1/1, and preferably 10/1 to 2/1, from the viewpoint of improving dischargeability. Further preferred.
The polymer particles containing the colorant, the water-insoluble organic compound, and the mixture containing water can be obtained by mixing an aqueous dispersion of polymer particles containing the colorant and the water-insoluble organic compound. The mixing operation is the same as described above.

The aqueous 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, an antifoaming agent that are usually used in an aqueous ink for inkjet recording. A rusting agent or the like may be added.
The average particle diameter of the polymer particles in the obtained water dispersion and water-based ink is preferably 0.01 to 0.5 μm, more preferably 0.01 to 0.5 m from the viewpoint of preventing clogging of the nozzles of the printer and dispersion stability. It is 0.3 μm, particularly preferably 0.01 to 0.2 μm. 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 usually about 5 × 10 ⁻³ wt%.

The water content in the aqueous dispersion and water-based ink of the present invention is preferably 30 to 90% by weight, more preferably 40 to 80% by weight. The water dispersion is obtained by dispersing water as a main medium, and the colorant is dispersed therein. The water-based ink is ink using water as the main medium.
The surface tension (20 ° C.) of the aqueous dispersion of the present invention is preferably 25 to 65 mN / m, more preferably 30 to 60 mN / m. Further, the surface tension (25 ° C.) of the water-based ink is preferably 20 to 45 mN / m, and more preferably 25 to 40 mN / m, from the viewpoint of securing good dischargeability from the ink nozzle.

In the following production examples, synthesis examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified. In addition, the measuring method of the weight average molecular weight of a polymer is as follows.
(Measurement of weight average molecular weight of polymer)
Gel chromatography method using a N, N-dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent [GPC apparatus (HLC-8120GPC) manufactured by Tosoh Corporation, column manufactured by Tosoh Corporation (TSK-GEL, α-M × 2), flow rate: 1 mL / min], using polystyrene as a standard substance.

Production Examples 1 to 3 (Production of Polymers A to C)
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.
While stirring the mixed solution in the reaction vessel under a nitrogen atmosphere, the temperature was raised to 75 ° C., and the mixed solution in the dropping funnel was gradually dropped over 3 hours. After 2 hours at 75 ° 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 75 ° C. for 2 hours and 80 ° C. for 2 hours to obtain a polymer solution. It was. 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-6 (S), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group (d) PP-800
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 12, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMMER PP-800
(D) PP-500
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 9, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMMER PP-500
(E) 43PAPE-600B
Phenolic polyethylene glycol polypropylene glycol monomethacrylate (average number of added moles of ethylene oxide = 6, average number of added moles of propylene oxide = 6, terminal: phenyl group): manufactured by NOF Corporation, trade name: BLEMMER 43PAPE-600B

Production Examples 4 to 9 (Production of pigment-containing polymer particle aqueous dispersions D to I)
25 parts of the polymer obtained by drying the polymer solution obtained in Production Examples 1 to 3 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and 6.7 parts of a neutralizing agent (5N aqueous sodium hydroxide solution) (degree of neutralization) 75%) and 230 parts of ion-exchanged water were added to neutralize the salt-forming group, and 75 parts of the following pigment was added thereto and mixed with a disper blade at 20 ° C. or lower for 1 hour. Using type 05 (dispersion medium: zirconia particles, temperature: 20 ° C. or less, dispersion medium / dispersion weight ratio: 8/2), dispersion treatment was performed for 2 hours at a peripheral speed of 12 m / s. The obtained mixture was subjected to 10-pass dispersion treatment with a microfluidizer (trade name, manufactured by Microfluidics) at a pressure of 150 MPa.
After adding 250 parts of ion-exchanged water to the obtained dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, a part of water was further removed, and a 5 μm filter (acetylcellulose membrane, outer diameter: Water of a pigment-containing polymer particle having a solid content concentration of 20% by filtering with a 25 mL needleless syringe (manufactured by Terumo Co., Ltd.) attached with 2.5 cm, manufactured by Fuji Film Co., Ltd., and removing coarse particles. A dispersion was obtained.

Synthesis Example 1 (Synthesis example of water-insoluble organic compound: trimellitic acid triester)
In a reaction vessel, 70 parts of trimellitic acid and 450 parts of Emulgen 104P (ethylene oxide 4 mol adduct of lauryl alcohol, manufactured by Kao Corporation) and 0.5 parts of tetraisopropoxytitanate are mixed and mixed with nitrogen gas. Then, the temperature was raised to 230 ° C. to conduct an esterification reaction. Further, the esterification reaction was completed by performing a reduced pressure reaction at the same temperature, and a water-insoluble organic compound was obtained by removing excess alcohol by topping. The obtained water-insoluble organic compound had trimellitic acid as a basic structure and had a 4-mol adduct of lauryl ethylene oxide at each end.

Synthesis Example 2 (Synthesis example of water-insoluble organic compound: phthalic acid diester)
In a reaction vessel, 100 parts of phthalic anhydride and 400 parts of an ethylene oxide 4 mol adduct of 2-ethylhexyl alcohol (Nippon Emulsifier: New Coal 1004) and 0.5 parts of tetraisopropoxy titanate are mixed and mixed to replace nitrogen gas. After fully performing, it heated up to 220 degreeC and performed esterification reaction. Furthermore, the esterification reaction was completed by carrying out a reduced pressure reaction at the same temperature, and a phthalic acid diester-based water-insoluble organic compound was obtained by removing excess alcohol by topping. The obtained water-insoluble organic compound had phthalic acid as a basic structure and a 4-mole adduct of 2-ethylhexyl group ethylene oxide at both ends.

Examples 1 to 13 (Production of water dispersion for inkjet recording)
80 parts of an aqueous dispersion D to I of pigment-containing polymer particles obtained in Production Examples 4 to 9 and 2 parts of a water-insoluble organic compound (however, Examples 8 and 10 are each 2 parts in total) are mixed. Using an ultrasonic homogenizer US-300T (manufactured by Nippon Seiki Seisakusho, Tip: φ26), it was treated at 200 μA for 10 minutes to obtain an aqueous dispersion of polymer particles containing a pigment (solid content concentration 20% by weight). 80 parts of an aqueous dispersion of polymer particles containing the obtained pigment were sealed in heat-resistant glass and heat-treated at a temperature described in Table 2 for 1 hour in a thermostatic dryer.
Next, 41 parts of a mixture of the water-dispersed pigment-containing polymer particles and the water-insoluble organic compound, 2 parts of 1.2-hexanediol, 17 parts of glycerin, 2 parts of 2-pyrrolidone, 1 part of triethanolamine, Mix 1 part of ethylene glycol monobutyl ether, 0.2 part of Surfynol 104PG50 (manufactured by Nissin Chemical Industry Co., Ltd.), 0.6 part of Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) and 35.2 parts of ion-exchanged water. By filtering the obtained mixed solution with a syringe having a capacity of 25 mL equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Film Co., Ltd.), and removing coarse particles. A water-based ink was obtained.

Comparative Example 1 (Production of water dispersion for inkjet recording)
A water-based ink was obtained in the same manner as in Example 1 except that ion-exchanged water was used instead of the water-insoluble organic compound.
Comparative Example 2 (Production of water dispersion for inkjet recording)
A water-based ink was obtained in the same manner as in Example 1 except that the treatment temperature was 20 ° C. shown in the table.

The dischargeability of the obtained water-based ink was evaluated by the following method. The results are shown in Table 2.
(Evaluation of ejectability)
Ink is set in a commercially available ink jet printer (product number: PX-V630, piezo method) manufactured by Seiko Epson Corporation, and it is confirmed that there is no problem in ejection. 1000 sheets were printed continuously on plain paper Xerox 4200 in the plain paper / fine mode, and the print states “Nuke” and “Bent” were evaluated according to the following criteria.
〔Evaluation criteria〕
1: There is neither “Nuke” nor “Bend” on the printed matter.
2: “Nuke” or “bend” is slightly seen on the printed matter.
3: “Nuke” or “bend” is seen on the printed matter.
Here, “nuke” means that there is a nozzle that has not ejected and ink does not land, and “bend” means that ink is landed with a deviation from a predetermined position.

Details of the pigments, water-insoluble organic compounds and the like shown in Table 2 are as follows.
(Pigment)
Cyan pigment: Copper phthalocyanine pigment (Pigment Blue 15: 3) PB15: 3 (Daiichi Seika Kogyo Co., Ltd., trade name Cyanine Blue 4920)
-Magenta pigment: Quinacridone pigment (CI Pigment Violet 19, manufactured by Clariant Japan KK, trade name: Hostaperm Red E5B 02)
Yellow pigment: diazo pigment (CI Pigment Yellow 74 [PY 74], manufactured by Sanyo Color Co., Ltd., trade name: FY7413)
Black pigment: Carbon black (Made by Mitsubishi Chemical Corporation, trade name: # 45, DBP oil absorption: 53 ml / 100 g)
(Water-insoluble organic compound)
・ Trimellitic acid triester: According to Synthesis Example 1 ・ Phthalic acid diester: According to Synthesis Example 2 ・ Dibutyl sebacate: Wako Pure Chemical Industries, Ltd., first grade ・ 2-ethylhexyl benzyl phthalate: Product made by J Plus Co., Ltd., trade name : OBzP
・ Benzyl alcohol: Wako Pure Chemical Industries, Ltd., special grade

  From Table 2, it can be seen that the water-based inks of the examples are superior in dischargeability compared to the water-based inks of the comparative examples.

Claims (7)

  Water that has a maximum weight of 5 g or less that can be dissolved in 100 g (20 ° C.) of a colorant, polymer particles, and water, and is at least one selected from the group consisting of ester compounds, ether compounds, aromatic alcohols, and sulfonic acid amide compounds. A method for producing an aqueous dispersion for inkjet recording, comprising a step of heat-treating a mixture containing an insoluble organic compound and water at 40 ° C. or higher.   The method for producing an aqueous dispersion for inkjet recording according to claim 1, wherein the colorant and the polymer particles are polymer particles containing a colorant.   The manufacturing method of the water dispersion for inkjet recording of Claim 1 or 2 whose temperature of heat processing is 50-90 degreeC.   The manufacturing method of the water dispersion for inkjet recording in any one of Claims 1-3 whose time of heat processing is 30 minutes or more.   The water dispersion for inkjet recording according to any one of claims 1 to 4, wherein a weight ratio of the polymer constituting the polymer particles to the water-insoluble organic compound (water-insoluble organic compound / polymer) is 1/10 to 2/1. Body manufacturing method.   The polymer constituting the polymer particles includes (a) a structural unit derived from a salt-forming group-containing monomer, (b) a structural unit derived from a macromer and / or (c) a structural unit derived from a hydrophobic monomer. The manufacturing method of the aqueous dispersion for inkjet recording in any one of -5.   An aqueous ink for inkjet recording, comprising the aqueous dispersion for inkjet recording obtained by the method according to claim 1.