JP2009149806A - Water-based ink for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous dispersion used for water-based ink for inkjet recording excellent in glossiness. <P>SOLUTION: The aqueous dispersion used for inkjet recording is an aqueous dispersion which comprises polymer particles containing a coloring agent, and a water-insoluble organic compound whose maximum solubility in 100 g water at 20°C is not more than 5 g, and wherein the polymer has a component unit derived from benzyl acrylate. The water-based ink for inkjet recording contains the aqueous dispersion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aqueous ink for inkjet recording and an aqueous dispersion used for the ink.

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 and 2).
Patent Document 1 discloses a water-based ink in which a pigment is contained in a vinyl polymer.
Patent Document 2 discloses an aqueous dispersion of vinyl polymer particles or polyester polymer particles containing a colorant, and water, in order to provide a water-based ink for ink-jet recording having high print density and excellent glossiness and image clarity. An aqueous dispersion for ink jet recording containing an insoluble organic compound (excluding a fatty acid derivative) is disclosed.
However, the water-based ink for ink jet recording is required to have further excellent gloss performance when printing on dedicated paper.

International Publication No. 00/39226 Pamphlet Japanese Patent Application Laid-Open No. 2007-077375

  An object of the present invention is to provide an aqueous dispersion used in an aqueous ink for inkjet recording having excellent gloss.

The present inventors have solved the above problems by using a polymer particle containing a colorant and an aqueous dispersion containing a specific water-insoluble organic compound and using a polymer having a structural unit derived from benzyl acrylate as the polymer. I found out.
That is, the present invention relates to an aqueous dispersion containing polymer particles containing a colorant and a water-insoluble organic compound having a maximum weight (20 ° C.) of 5 g or less that can be dissolved in 100 g of water, wherein the polymer is benzyl acrylate. An aqueous dispersion for inkjet recording having a structural unit derived therefrom, and an aqueous ink for inkjet recording containing the same.

  The aqueous ink containing the aqueous dispersion for inkjet recording of the present invention is excellent in gloss.

The aqueous dispersion for inkjet recording of the present invention contains polymer particles containing a colorant and a water-insoluble organic compound having a maximum weight (20 ° C.) that can be dissolved in 100 g of water of 5 g or less, and the polymer is derived from benzyl acrylate. It has a structural unit.
By having a structural unit derived from benzyl acrylate, it is considered that the flexibility of the polymer is increased and the fusibility between the polymer particles is increased, thereby further increasing the glossiness.
Hereinafter, each component used in the present invention will be described in detail.

(Water-insoluble organic compound)
In the present invention, a water-insoluble organic compound (hereinafter also simply referred to as “water-insoluble organic compound”) having a maximum weight (20 ° C.) that can be dissolved in 100 g of water of 5 g or less is used.
It is considered that at least a part of the water-insoluble organic compound is contained in the polymer to improve its flexibility. The water-insoluble organic compound improves the flexibility of the polymer, so that the fusing property between the polymer particles containing the colorant discharged from the nozzle of the ink jet recording apparatus is increased, and the polymer particle containing the colorant is placed on the recording paper. It is considered that the gloss of the printed matter is improved by uniformly diffusing and smoothing the printing surface.

From the viewpoint of improving the glossiness of the ink, the water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, and more preferably a molecular weight of 100 to 1,000.
The maximum weight (20 ° C.) that can be dissolved in 100 g of water of the water-insoluble organic compound is 5 g or less, preferably 3 g or less, more preferably 1 g or less.

The water-insoluble organic compound is preferably one or more compounds selected from the group consisting of an ester compound, an ether compound, a sulfonic acid amide compound, a fatty acid amide compound, and a fatty acid anhydride for easy inclusion in polymer particles. One or more water-insoluble organic compounds selected from the compounds (A) to (C) are more preferable.
(A) The group which consists of the fatty acid monoester compound obtained from a monohydric fatty acid and monohydric alcohol, the fatty acid amide compound obtained from monohydric fatty acid and ammonia or a C1-C3 lower amine, and the fatty acid anhydride of monohydric fatty acid One or more compounds selected from (hereinafter also referred to as fatty acid derivative (A))
(B) Ester or ether compound having two or more ester or ether bonds in the molecule (C) One or more ester or ether bonds in the molecule, carboxy group, sulfonic acid group, sulfuric acid group, phosphoric acid An ester or ether compound having at least one functional group selected from the group consisting of a residue, a phosphonic acid group, a carbonyl group, an epoxy group and a hydroxyl group

Here, in the fatty acid derivative (A), the monovalent fatty acid is preferably a linear or branched saturated or unsaturated aliphatic carboxylic acid having 8 to 22 carbon atoms, octanoic acid, 2-ethylhexanoic acid, laurin. Examples include acid, myristic acid, stearic acid, oleic acid, palmitic acid, behenic acid and the like.
In the fatty acid derivative (A), the monohydric alcohol may be a linear or branched aliphatic alcohol having 1 to 18 carbon atoms, preferably 2 to 13 carbon atoms (for example, methyl alcohol, ethyl alcohol, butyl alcohol, hexyl alcohol). Octyl alcohol, decyl alcohol, dodecyl alcohol) and the like.
In the fatty acid derivative (A), the lower amine having 1 to 3 carbon atoms includes methylamine, ethylamine, propylamine, isopropylamine and the like.
Specific examples of the fatty acid derivative (A) include octyl octoate, isotridecyl myristate, methyl stearate, ethyl stearate, butyl stearate, methyl oleate, ethyl oleate, methyl palmitate, ethyl palmitate, methyl behenate And fatty acid monoester compounds such as ethyl behenate, fatty acid amide compounds such as oleic acid amide and stearic acid amide, and fatty acid anhydrides such as oleic anhydride.

  The number of ester or ether bonds in compound (B) is preferably 2 to 3. A compound having an ester bond and an ether bond may be used. The ester or ether bond of the compound (C) is preferably 1 to 3, and 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.

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

Specific examples of the compound (B) and the compound (C) include (1) aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, (3) cycloalkane (ken) carboxylic acid ester, and (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) Examples include glycol alkyl ethers, (13) glycol alkyl esters, (14) trimethylolpropane ethers or esters, and (15) pentaerythritol ethers or esters.
Among these, from the viewpoint of image clarity and gloss, the compounds of (1) to (5), (8) and (10) are preferred, (1) aliphatic di- or tricarboxylic acid ester, (2) aromatic It is more preferable that it is at least one selected from the group consisting of an aromatic carboxylic acid ester, (3) a cycloalkane (ken) carboxylic acid ester, and (4) a phosphoric acid ester, (1) an aliphatic dicarboxylic acid ester, ( 2) One or more selected from the group consisting of 2) aromatic di- or tricarboxylic acid ester, (3) cycloalkane (ken) carboxylic acid ester, and (4) phosphoric acid ester is most preferable.
(1) Aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, and (3) cycloalkane (ken) carboxylic 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 a linear or branched alkyl or alkenyl group having 2 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, and 7 carbon atoms from the viewpoint of improving the gloss of printed matter. -23, preferably 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. 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) The oxyacid ester is preferably a compound represented by the following formula (5).

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above. R ¹ and R ² may be the same or different.)
Specific examples of the oxyester include triethyl acetylcitrate, tributyl acetylcitrate, methyl acetylricinoleate and the like.

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

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above. R ¹ and R ² may be the same or different.)
Specific examples of the glycol ester include diethylene glycol dibenzoate and triethylene glycol di (2-ethylhexoate).

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

(In the formula, R ¹ has the same meaning as described above. R ⁴ and R ⁵ each independently represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and R ⁶ represents an alkanediyloxy group having 1 to ⁶ carbon atoms. Show.)
Specific examples of the epoxy ester include butyl epoxy stearate and octyl epoxy stearate.

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

(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 the sulfonamide include o- and p-toluenesulfonamide, N-butylbenzenesulfonamide and the like.

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

(In the formula, R ¹ , R ² and R ³ have the same meaning as described above and may be the same or different. P represents a number of 1 to 18, preferably 1 to 10.)
Specific examples of the polyester include poly (1,2-butanediol adipate), poly (1,3-butanediol adipate) and the like.
(10) Specific examples of the glyceryl alkyl ether include glyceryl monoether, glyceryl diether, and glyceryl triether. In these, the glyceryl monoether which has a C8-C30 linear or branched alkyl group is preferable. The alkyl group has 8 to 30 carbon atoms, preferably 8 to 22 carbon atoms, and more preferably 8 to 14 carbon atoms.
Examples of the alkyl group include 2-ethylhexyl, (iso) octyl, (iso) decyl, (iso) dodecyl, (iso) myristyl, (iso) cetyl, (iso) stearyl, and (iso) behenyl groups.
There is no restriction | limiting in particular about the position of an alkyl group, Either 1-alkyl glyceryl monoether and 2-alkyl glyceryl monoether may be sufficient.

(11) Specific examples of the glyceryl alkyl ester include glyceryl monoalkyl ester, glyceryl dialkyl ester, and glyceryl trialkyl ester.
Among these, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, palmitic acid) Linear aliphatic carboxylic acids such as branched aliphatic carboxylic acids such as pivalic acid) esters are preferred. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
More specifically, glyceryl triacetate, glyceryl diacetate, glyceryl monoacetate and the like can be mentioned.

(12) Specific examples of glycol alkyl ether include glycol monoalkyl ether and glycol dialkyl ether.
Examples of the glycol of the compound (12) include ethylene glycol and neopentyl glycol. Examples of the alkyl group of the compound (12) include a linear or branched alkyl group having 1 to 22 carbon atoms. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.

(Coloring agent)
The colorant used in the present invention is not particularly limited, and pigments, hydrophobic dyes, water-soluble dyes (acidic dyes, reactive dyes, direct dyes, etc.) can be used, but water resistance, dispersion stability and resistance From the viewpoint of abrasion, pigments and hydrophobic dyes are preferable. Among them, it is more 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, anthraquinone 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 is not particularly limited as long as it can be contained in the polymer particles. 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, chromatic colorants are preferable from the viewpoints of glossiness and image clarity. Here, the “chromatic color” excludes white and black and gray which is an intermediate color thereof.
The above colorants can be used alone or in admixture of two or more at any ratio.

(Polymer particles containing colorant)
In the present invention, the polymer particles containing a colorant are particles formed by containing a colorant in a polymer. The polymer used for the polymer particles containing the colorant is used to improve the glossiness by interaction with the water-insoluble organic compound. The polymer of the polymer particles containing the colorant used in the present invention has a structural unit derived from benzyl acrylate in order to improve glossiness.
The polymer used for the polymer particles containing the colorant 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.

(polymer)
As the polymer, a monomer mixture (hereinafter referred to as “monomer”) containing (a) a salt-forming group-containing monomer (hereinafter also referred to as “(a) component”) and (b) benzyl acrylate (hereinafter also referred to as “(b) component”). A polymer obtained by copolymerizing a mixture (also referred to as “mixture”) is preferable. This polymer has a structural unit derived from the component (a) and a structural unit derived from the component (b). Furthermore, a polymer obtained by copolymerizing (c) a macromer (hereinafter also referred to as “component (c)”) is more preferable. This polymer has a structural unit derived from the component (a), a structural unit derived from the component (b), and further has a structural unit derived from the component (c).

(A) The salt-forming group-containing monomer is used from the viewpoint of enhancing the dispersion stability of the resulting dispersion. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group.
Examples of the salt-forming group-containing monomer include a cationic monomer and an anionic monomer. Examples thereof include those described in 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-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) Benzyl acrylate is used to improve glossiness.
(C) The macromer can be used from the viewpoint of enhancing the dispersion stability of the polymer particles when the polymer particles contain a colorant. The macromer has a number average molecular weight of 500 to 100,000, preferably 1,000. Macromers which are monomers having 10,000 to 10,000 polymerizable unsaturated groups are exemplified. In addition, the number average molecular weight of (c) macromer is measured using polystyrene as a standard substance by gel chromatography using 1 mmol / L dodecyldimethylamine-containing chloroform as a solvent.
Among the macromers, a styrenic macromer having a polymerizable functional group at one end is preferable 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.
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 styrenic monomer in the styrenic macromer is preferably 50% by weight or more, more preferably 70% by weight or more from the viewpoint of increasing the affinity with the pigment.

(C) 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 (10).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} O] _{t -Si (CH 3) 3 (} 10)
(In the formula, t represents a number of 8 to 40).
(C) As a styrene-type macromer which can be obtained commercially as a component, the brand name of Toa Gosei Co., Ltd., AS-6 (S), AN-6 (S), HS-6 (S) etc. are mentioned, for example. It is done.

(D) The hydrophobic monomer is used from the viewpoint of improving the printing density. Examples of the hydrophobic monomer include alkyl (meth) acrylate, styrene monomer, benzyl methacrylate and the like.
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.
Examples of the styrenic monomer include those described above.
Among the components (d), from the viewpoint of improving the printing density, styrene monomers are preferable, and styrene and 2-methylstyrene are more preferable. The content of the styrenic monomer in the component (d) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving the printing density.

The monomer mixture may further contain (e) a hydroxyl group-containing monomer (hereinafter sometimes referred to as “component (e)”). (E) A hydroxyl group-containing monomer is used to further increase the dispersion stability.
As the component (e), 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 (f) a monomer represented by the following formula (11) (hereinafter sometimes referred to as “component (f)”).
^{_{CH 2 = C (R 7)}} COO (R 8 O) p R 9 (11)
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 (f) is used to further improve the ink discharge performance.
In the formula (11), 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 (f) include methoxypolyethylene glycol (1 to 30: the value of p in formula (11); hereinafter the same) (meth) acrylate, methoxypolytetramethylene glycol (1 to 30) ( (Meth) acrylate, ethoxy polyethylene glycol (1-30) (meth) acrylate, octoxy polyethylene glycol (1-30) (meth) acrylate, polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether, (iso) Propoxy polyethylene glycol (1-30) (meth) acrylate, butoxy polyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Copolymerization) (1-30, ethylene glycol therein: 1-29) (meth) acrylate. Among these, octoxypolyethylene glycol (1-30) (meth) acrylate and polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether are preferable.

Specific examples of the commercially available (e) and (f) 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 (f) can be used alone or in admixture of two or more.

Content derived from the components (a) to (f) in the monomer mixture at the time of polymer production (content as an unneutralized amount; the same applies hereinafter) or the components (a) to (f) in the polymer The content of the 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 5 to 98% by weight, more preferably 10 to 70% by weight, still more preferably 15 to 65% by weight, and still more preferably 20 to 65% by weight, from the viewpoint of improving glossiness. %.
The content of the component (c) is preferably 3 to 20% by weight, more preferably 5 to 15% by weight, from the viewpoint of dispersion stability.
The content of component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight, from the viewpoint of printing density.
The content of component (e) is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The content of the component (f) is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of dischargeability.
The total content of [component (a) + component (b)] in the monomer mixture is preferably 30 to 100% by weight, more preferably 40 to 100, from the viewpoint of dispersion stability and gloss of the resulting dispersion. % By weight, more preferably 50-90% by weight.
The weight ratio of [component (a) / component (b)] is preferably 0.1 to 0.75, more preferably 0.1 to 0.67, and still more preferably 0.15 to 0.15 from the viewpoint of gloss. 0.5.
Further, the total content of [(b) component + (c) component + (d) component] is preferably 50 to 90% by weight, more preferably 60 to 90%, from the viewpoint of dispersion stability of the resulting dispersion. % By weight.

(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 from 5,000 to 500,000, more preferably from 10,000 to 400,000, and even more preferably from 10,000 to 300,000, from the viewpoint of printing density, glossiness, and dispersion stability of the colorant. 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 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 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. The acid value or amine value of the polymer is preferably 50 to 200, more preferably 50 to 150.

  There is no limitation in particular in the manufacturing method of the aqueous dispersion for inkjet recording of this invention. For example, the water-insoluble organic compound is contained in the polymer particles by mixing with an aqueous dispersion of polymer particles containing a colorant and stirring appropriately. A part of the water-insoluble organic compound may be present in addition to the polymer particles.

Such an aqueous dispersion can be obtained, for example, by the following steps (1) to (2).
Step (1): A step of dispersing a mixture containing a polymer, an organic solvent, a colorant, water and, if necessary, a neutralizing agent to obtain a dispersion of polymer particles containing the colorant Step (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. In step (1), first, the polymer is dissolved in an organic solvent. Next, 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 is preferable. 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 polymer is 2 to 2% by weight. It is preferably 40% by weight, more preferably 3 to 20% by weight, and water is preferably 10 to 70% by weight, more preferably 20 to 70% by weight.
When the polymer has a salt-forming group, it is preferable to use a neutralizing agent, but the degree of neutralization is not particularly limited. Usually, it is preferable that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5 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. The solubility in water is preferably 50% by weight or less and 20% by weight or more at 20 ° C., and methyl ethyl ketone and methyl isobutyl ketone are particularly preferable.

There is no restriction | limiting in particular in the dispersion method of the mixture in the said process (2). Although it is possible to atomize the polymer particles until the average particle size of the polymer particles reaches a desired particle size without performing pre-dispersion, it is preferable that after pre-dispersion, additional dispersion is performed by further applying shear stress to obtain polymer particles. It is preferable to control the average particle size of the particles so as to have a desired particle size. 5-50 degreeC is preferable and, as for the dispersion | distribution of a process (2), 10-35 degreeC is still more preferable.
When preliminarily dispersing the mixture, a commonly used mixing and stirring device such as an anchor blade can be used. Among the mixing and stirring apparatuses, high-speed stirring and mixing apparatuses such as Ultra Disper [Asada Steel Co., Ltd., trade name], Ebara Milder [Ebara Seisakusho Co., Ltd., trade name], TK Homomixer [Primix Co., Ltd., trade name] are preferable .
As means for giving 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) Examples thereof include a chamber type high-pressure homogenizer such as a homo-valve type high-pressure homogenizer, a microfluidizer [Microfluidics, trade name], and a nanomizer [Nanomizer Co., trade name]. 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. The organic solvent in the aqueous dispersion containing the polymer particles containing the obtained colorant 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 one 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.

  The aqueous dispersion for inkjet recording of the present invention includes the steps (1) to (2), and a water-insoluble organic compound is present during or after at least one of the steps (1) to (2). However, it is preferable to obtain the polymer particles obtained by mixing the water dispersion of the polymer particles containing the colorant obtained in the step (2) with a water-insoluble organic compound.

The mixing ratio of the aqueous dispersion of the polymer particles containing the colorant and the water-insoluble organic compound is 100 parts by weight of the solid content of the aqueous dispersion of the polymer particles containing the colorant. It is preferably ˜100 parts by weight, preferably 3 to 50 parts by weight, and more preferably 3 to 20 parts by weight. In the mixing method, the water-insoluble organic compound may be added to the aqueous dispersion of polymer particles containing the colorant, or vice versa. The mixing temperature is preferably about 5 to 50 ° C.
The resulting aqueous dispersion is an aqueous dispersion of polymer particles containing a water-insoluble organic compound and a colorant.

An aqueous dispersion of polymer particles containing a colorant may be used as an aqueous ink as it is, but a wetting agent, a penetrating agent, a dispersing agent, a viscosity modifier, an antifoaming agent, an antifungal agent which are usually used in an aqueous ink for inkjet recording. You may add an agent, a rust preventive agent, etc.
The average particle diameter of the polymer particles containing the colorant in the obtained water dispersion and water-based ink is preferably 0.01 to 0.5 μm, more preferably from the viewpoint of preventing clogging of the nozzle of the printer and dispersion stability. Is 0.03 to 0.3 μm, more preferably 0.05 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 content of each component and the ratio thereof in the aqueous dispersion or aqueous ink of the present invention are as follows.
The lower limit of the content of the water-insoluble organic compound is preferably 0.1% by weight or more, more preferably 0.15% by weight or more, particularly preferably 0.2% by weight, from the viewpoint of improving image clarity and gloss. Above, most preferably 0.5% by weight or more, and the upper limit is preferably 10% by weight or less, more preferably 5% by weight or less, particularly preferably 3% by weight or less, and most preferably 2% by weight or less. From these viewpoints, the content of the water-insoluble organic compound is preferably 0.1 to 10% by weight, more preferably 0.15 to 5% by weight, particularly preferably 0.2 to 3% by weight, 2% by weight is most preferred.
The polymer content of the polymer particles containing the colorant (the amount of solids excluding the water-insoluble organic compound and the colorant; the same shall apply hereinafter) is 0.5 to 30% from the viewpoints of print density, image clarity and gloss. % Is preferred, 1 to 20% by weight is more preferred, and 1 to 15% by weight is particularly preferred.
The content of the colorant is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, and particularly preferably 2 to 20% by weight from the viewpoint of printing density.
The weight ratio of [water-insoluble organic compound / polymer of polymer particles containing colorant] is preferably 1/100 to 5/1, more preferably 1/50 to 2/1, from the viewpoint of improving glossiness. 1/50 to 1/1 is more preferable, 1/30 to 1/1 is still more preferable, and 1/10 to 1/1 is particularly preferable.
The weight ratio of [water-insoluble organic compound / colorant] is preferably 1/40 to 5/1, and more preferably 1/30 to 1/1, from the viewpoint of gloss.
The weight ratio of [polymer of colorant-containing polymer particles / colorant] is preferably 5/95 to 90/10 from the viewpoint of dispersion stability of the polymer particles containing the colorant. More preferably, it is -75/25, and 20/80-50/50 are especially preferable.
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. In addition, the measuring method of the weight average molecular weight of a polymer is as follows.
Gel chromatography method using a N, N-dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a polymer weight average molecular weight solvent [GPC apparatus manufactured by Tosoh Corporation (HLC-8120GPC), Tosoh Corporation column (TSK-GEL, α-M × 2), flow rate: 1 mL / min] was measured using polystyrene as a standard substance.

Production Examples 1 to 3 (Polymer Production Examples)
In a reaction vessel, 20 parts of methyl ethyl ketone, 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol), and 10% of 200 parts of each monomer shown in Table 1 were mixed and thoroughly replaced with nitrogen gas. A mixed solution was obtained.
On the other hand, the remaining 90% of the monomers shown in Table 1 were charged into a dropping funnel, and 0.27 part of the polymerization chain transfer agent, 60 parts of methyl ethyl ketone and a radical polymerization initiator (2,2′-azobis (2,4-dimethyl) were added. Valeronitrile)) 1.2 parts were added and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.
Under a nitrogen atmosphere, the mixed solution in the reaction vessel was heated to 65 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped over 3 hours. After 2 hours at 65 ° C. from the end of dropping, a solution obtained by dissolving 0.3 part of the radical polymerization initiator in 5 parts of methyl ethyl ketone was added, and further aged at 65 ° C. for 2 hours and 70 ° 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.
(C) Styrene macromer, manufactured by Toa Gosei Co., Ltd., trade name: AS-6 (S), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group (e) M-90G
Polyethylene glycol monomethacrylate (average number of moles of ethylene oxide added = 9, terminal: methyl group): Shin-Nakamura Chemical Co., Ltd., trade name: NK ester M-90G
(E) 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) PP-1000
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 14, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMMER PP-1000

Example 1
25 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and 5.7 parts of a neutralizer (5N aqueous sodium hydroxide solution) was contained therein (degree of neutralization 60). %) And 230 parts of ion-exchanged water were added to neutralize the salt-forming group, and 75 parts of quinacridone pigment (CI Pigment Violet 19, Clariant Japan Co., Ltd., trade name: Hostaperm Red E5B02) was added. After mixing at 20 ° C. for 1 hour, it was mixed and dispersed at 20 ° C. for 4 hours using a bead mill type dispersing machine UAM05 type (manufactured by Kotobuki Industries Co., Ltd.). The obtained dispersion was further subjected to 10-pass dispersion treatment at a pressure of 200 MPa with a microfluidizer (trade name, manufactured by Microfluidics).
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.

  40 parts of an aqueous dispersion of the obtained pigment-containing polymer particles and 1 part of octylbenzyl phthalate were mixed and stirred to contain at least a part of octylbenzyl phthalate in the polymer particles. In this mixed solution, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of 1,2-dodecanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 Part, 0.3 part of Proxel XL2 (manufactured by Avicia Co., Ltd.) and 39.7 parts of ion-exchanged water were mixed, and the resulting mixture was filtered with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, Fuji A water-based ink shown in Table 2 was obtained by filtering with a syringe having a capacity of 25 mL equipped with Film Co., Ltd. and removing coarse particles.

Example 2
A water-based ink shown in Table 2 was obtained in the same manner as in Example 1 except that n-butyl oleate was used in place of octylbenzyl phthalate in Example 1.

Example 3
In Example 2, the polymer solution obtained in Production Example 2 was used instead of the polymer solution obtained in Production Example 1, and 4.1 parts of neutralizing agent (5N aqueous sodium hydroxide solution) (degree of neutralization 60%) A water-based ink shown in Table 2 was obtained in the same manner as in Example 2, except that 230 parts of ion-exchanged water was added to neutralize the salt-forming group.

Example 4
In Example 2, the addition of n-butyl oleate is performed before the dispersion treatment by the microfluidizer, and the addition amount is changed to 0.6 part. A water-based ink was obtained.

Comparative Example 1
In Example 3, water-based inks shown in Table 2 were obtained in the same manner as in Example 3 except that the polymer obtained in Production Example 3 was used instead of the polymer obtained in Production Example 2.

Comparative Example 2
In Example 2, water-based inks shown in Table 2 were obtained in the same manner as in Example 2 except that n-butyl oleate was not used.

Next, the glossiness of the water-based inks obtained in Examples 1 to 4 and Comparative Examples 1 to 2 was evaluated by the following method. The results are shown in Table 2.
(1) Evaluation of glossiness Using a printer (model number: PX-A650, piezo method) manufactured by Seiko Epson Corporation, commercially available dedicated paper (photo paper <gloss> (60 ° glossiness: 41), manufactured by Seiko Epson Corporation, (Product name: KA4100PSK) (printing condition = paper type: photo print paper, mode setting: photo), left for 24 hours at 25 ° C, and glossiness of 20 ° (manufactured by Nippon Denshoku Industries Co., Ltd.) The product name: HANDY GLOSSMETER, product number: PG-1) was measured 5 times, and the average value was obtained. The larger the value, the higher the glossiness.

  From Table 2, it can be seen that the water-based inks of Examples 1 to 4 have higher gloss than Comparative Examples 1 and 2.

Claims (6)

  A water dispersion containing polymer particles containing a colorant and a water-insoluble organic compound having a maximum weight (20 ° C.) that can be dissolved in 100 g of water of 5 g or less, wherein the polymer has a structural unit derived from benzyl acrylate Water dispersion for inkjet recording.   The water dispersion for inkjet recording according to claim 1, wherein the water-insoluble organic compound is at least one selected from the group consisting of ester compounds, ether compounds, sulfonic acid amide compounds, fatty acid amide compounds, and fatty acid anhydrides.   A fatty acid monoester compound obtained from a monovalent fatty acid and a monohydric alcohol, a fatty acid amide compound obtained from a monovalent fatty acid and ammonia or a lower amine having 1 to 3 carbon atoms, and a monohydric fatty acid anhydride The aqueous dispersion for inkjet recording according to claim 1 or 2, wherein the aqueous dispersion is one or more selected from the group consisting of:   The aqueous dispersion for inkjet recording according to any one of claims 1 to 3, wherein the polymer is a polymer obtained by copolymerizing a monomer mixture containing (a) a salt-forming group-containing monomer and (b) benzyl acrylate.   The inkjet according to any one of claims 1 to 4, wherein a weight ratio [(a) / (b)] of (a) a salt-forming group-containing monomer to benzyl acrylate is 0.1 to 0.75. Water dispersion for recording.   An aqueous ink for inkjet recording, comprising the aqueous dispersion for inkjet recording according to any one of claims 1 to 5.