JP2007077375A - Water-based ink for ink-jet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain water-based ink for ink-jet recording, having high print density and gloss and excellent image clarity, a printed matter obtained by printing with the ink and to provide a method for producing a water dispersion for ink-jet recording. <P>SOLUTION: The water dispersion for ink-jet recording comprises a water dispersion of vinyl polymer particles or polyester-based polymer particles containing a colorant (B) and a water-insoluble organic compound (except fatty acid derivative) (A). The water-based ink comprises the water dispersion for ink-jet recording. The printed matter is obtained by printing with the water-based ink. The method for producing the water dispersion is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aqueous ink for inkjet recording, an aqueous dispersion used for the ink, a printed matter printed using the ink, and a method for producing 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)
Patent Document 1 discloses a water-based ink in which a pigment is contained in a vinyl polymer.
Patent Document 2 discloses a water-based ink containing an oil film-forming component obtained by dissolving a water-insoluble resin in order to suppress color bleeding, but the content of the water-insoluble resin is required to be dissolved. There are few and not enough functions.
Patent Document 3 discloses an ink containing 10 to 1000 ppm of phthalic acid diester and latex in order to form a glossy image. However, the content of phthalic acid diester is small and sufficient functions are exhibited. It has not been.
Patent Document 4 discloses a microcapsule-containing colored fine particle dispersion in which urethane particles contain a hydrophobic dye, a hydrophobic polymer, and a high-boiling organic solvent.
Patent Document 5 discloses an inkjet pigment ink in which the total content of fatty acid derivatives in the pigment ink is 1.0% by mass or less and the pigment particles are coated with a water-insoluble polymer.
However, the above inks are not satisfactory in terms of glossiness, image clarity and the like.

International Publication No. 00/39226 Pamphlet Japanese Patent Application Laid-Open No. 8-157761 JP 2003-183554 A JP 2004-75759 A JP 2003-147236 A

  The present invention provides an aqueous ink excellent in glossiness and image clarity in addition to a sufficient print density, a printed matter having excellent glossiness and image clarity (including a printed matter, the same applies hereinafter), and an aqueous dispersion for inkjet recording. It is an object to provide a manufacturing method.

The present invention provides the following [1] to [4].
[1] An aqueous dispersion for ink jet recording containing an aqueous dispersion of vinyl polymer particles or polyester polymer particles containing a colorant (B), and a water-insoluble organic compound (excluding a fatty acid derivative) (A), and Water-based ink containing it.
[2] A water-based ink for ink-jet recording containing an aqueous dispersion of a pigment, wherein the water-based ink has a pigment concentration of 4 to 8% by weight, and is solid on ink-jet photographic paper with an ink size of 3 pl and resolution of 1440 dpi × 720 dpi. A water-based ink for inkjet recording, in which the correlation distance in the vertical direction with respect to the printing direction is 4 μm or more with respect to the amount of light reflected when the printing surface is irradiated with laser light from the vertical direction.
[3] Printed matter obtained by printing the water-based ink using an ink jet recording apparatus.
[4] The following steps (1) to (3) are included, and a water-insoluble organic compound (excluding the fatty acid derivative) is allowed to exist during or after at least one of steps (1) to (3). A method for producing the water dispersion for ink jet recording.
Step (1): Step of obtaining a mixture containing a water-insoluble polymer, an organic solvent, a colorant, and water Step (2): Step of dispersing the mixture obtained in Step (1) Step (3): Step ( 2) Step of removing the organic solvent from the obtained dispersion to obtain an aqueous dispersion of water-insoluble polymer particles containing a colorant.

The water-based ink containing the aqueous dispersion for inkjet recording of the present invention gives excellent glossiness and image clarity when printed on special paper in addition to a sufficient print density when printed on plain paper. For this reason, it can be suitably used as an ink for inkjet recording.
Further, a printed matter obtained by printing the aqueous ink of the present invention using an ink jet recording apparatus is excellent in glossiness and image clarity.

  The aqueous dispersion for inkjet recording of the present invention is a vinyl polymer particle or a polyester polymer particle (hereinafter collectively referred to simply as “polymer particle”) containing a colorant (B) (hereinafter also simply referred to as “colorant”). ) And a water-insoluble organic compound (excluding a fatty acid derivative) (A) (hereinafter also simply referred to as “water-insoluble organic compound (A)”). Hereinafter, each of these components will be described sequentially.

(Water-insoluble organic compound (A))
It is considered that the water-insoluble organic compound (A) used in the present invention is at least partially contained in polymer particles to improve its flexibility. The water-insoluble organic compound (A) improves the flexibility of the polymer particles, so that the fusibility of the polymer particles ejected from the nozzle of the ink jet recording apparatus is increased, and the polymer particles are uniformly diffused on the recording paper, It is considered that the gloss and image clarity of the printed matter are improved by the smooth printing surface.
Since the fatty acid derivative does not exhibit the above-described effects in the present invention, the water-insoluble organic compound (A) used in the present invention does not contain a fatty acid derivative.
Here, the fatty acid derivative removed from the water-insoluble organic compound (A) is a fatty acid monoester compound produced from a monovalent fatty acid that is a saturated or unsaturated alkylcarboxylic acid and a monohydric alcohol, the fatty acid and ammonia, or carbon number 3 The fatty acid amide compound formed from the following lower amines and the fatty acid anhydride formed from the said fatty acid are said.
More specifically, the fatty acid ester refers to an ester compound produced from a saturated or unsaturated alkyl carboxylic acid having 8 to 22 carbon atoms and an alcohol, such as isotridecyl myristate, methyl stearate, methyl oleate, Examples thereof include methyl palmitate and methyl behenate, and fatty acid amides include, for example, oleic acid amide and stearic acid amide, and fatty acid anhydrides include, for example, anhydrous olein and the like. However, these fatty acid derivatives may be contained in the aqueous dispersion of the present invention as long as the object of the present invention is not impaired.

The water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, more preferably a molecular weight of 100 to 1,000, from the viewpoint of improving the glossiness and image clarity of the ink.
The amount of water-insoluble organic compound dissolved in 100 g of water (20 ° C.) is 5 g or less, preferably 3 g or less, more preferably 1 g or less.
In order to improve the flexibility of the polymer, the water-insoluble organic compound 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.
Further, 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 (A)] − [Log P value of the vinyl polymer or polyester polymer]] is −4 to It is preferably 8, more preferably -2 to 6, still more preferably -1.5 to 5, and particularly preferably -1 to 4.
Here, “Log P value” means the logarithmic value of 1-octanol / water partition coefficient of water-insoluble organic compounds, and is 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. The LogP value of the polymer can be obtained by a calculation method described later.

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

As the monovalent carboxylic acid, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, Linear aliphatic carboxylic acids such as palmitic acid, branched aliphatic carboxylic acids such as pivalic acid, unsaturated aliphatic carboxylic acids such as acrylic acid and methacrylic acid), and aromatic carboxylic acids having 6 to 12 carbon atoms (for example, As the polyvalent 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 water-insoluble organic compound include (1) aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, (3) phosphoric acid ester, (4) cycloalkane (ken) carboxylic acid ester, (5) Oxyacid ester, (6) glycol ester, (7) epoxy ester, (8) sulfonamide, (9) polyester, (10) glyceryl alkyl ether, (11) glyceryl alkyl ester, (12) glycol alkyl ether, ( 13) glycol alkyl ester, (14) ether or ester of trimethylolpropane, (15) ether or ester of pentaerythritol, and the like.
Among these, from the viewpoint of image clarity and gloss, the compounds of (1) to (3), (5), (8) and (10) are preferable, and (1) aliphatic di- or tricarboxylic acid ester, It is preferably at least one selected from the group consisting of (2) aromatic carboxylic acid esters and (3) phosphoric acid esters, (1) aliphatic dicarboxylic acid esters, (2) aromatic di- or tricarboxylic acid esters And (3) it is most preferably at least one selected from the group consisting of phosphate esters.

  (1) The aliphatic dicarboxylic acid ester is preferably a compound represented by the following formula (1).

(In formula (1), R ¹ and R ² are each a hydrogen atom, a linear, branched or cyclic hydrocarbon group having 1 to 18 carbon atoms, an aralkyl group having 7 to 22 carbon atoms, and 6 to 22 carbon atoms. R ¹ and R ² may be the same or different, and R ³ may have an unsaturated group having 1 to 18 carbon atoms. A divalent aliphatic hydrocarbon group, R ^{1 to} R ³ may have a substituent, n represents an average addition mole number of 0 to 20, and AO represents an alkyleneoxy group. )

R ¹ and R ² are preferably a linear or branched alkyl group or alkenyl group having 2 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, from the viewpoint of improving glossiness and image clarity of printed matter. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, 2-ethylhexyl group, octyl group, dodecyl group, cetyl group and the like. The same applies to the following equations.
R ³ is preferably an alkylene group or an alkenylene group, and specifically includes an ethylene group, a propylene group, a trimethylene grave, a butylene group, a hexylene group, a 2-ethylhexylene group, an octylene group, a dodecylene group, and the like. Is an alkylene group having 2 to 15 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms. The same applies to the following equations.
n is preferably 0 to 15, more preferably 0 to 12, and particularly preferably 2 to 10.
AO is an alkyleneoxy group having 2 to 4 carbon atoms such as ethyleneoxy group (EO), propyleneoxy group (PO), or butyleneoxy group (BO). When n is 2 or more, AO is the same or different. If they are different, AO may be added in blocks or randomly.
Examples of the substituent that can be bonded to R ^{1 to} R ³ include halogen atoms such as fluorine, chlorine and bromine atoms, and carbon atoms of 1 to 3 such as methyl, ethyl, propyl, isopropyl, isobutyl, t-butyl, hexyl and lauryl. 12 alkyl groups, cycloalkyl groups such as cyclohexyl groups, aryl groups such as phenyl groups, alkoxy groups having 1 to 12 carbon atoms such as methoxy, ethoxy and isopropoxy groups, aryloxy groups such as phenyloxy groups, methoxycarbonyl groups Examples include alkoxycarbonyl groups such as acetyl, 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, and ester groups. . These substituents may be one or a combination of two or more.

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

  (2) The aromatic carboxylic acid ester is preferably a (di or tri) carboxylic acid ester represented by the following formula (2).

(In formula (2), R ¹ and R ² are the same as described above. R ¹ and R ² may be the same or different.)

  (2) Specific examples of the aromatic carboxylic acid ester 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 esters such as phthalate, nonylbenzyl phthalate, stearyl benzyl phthalate, octyl decyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, bis (dimethylcyclohexyl) phthalate, bis (t-butylcyclohexyl) phthalate, ethyl phthalyl ethyl glycolate, dibutyl tri Trimellitic acid esters such as melitrate, diisobutyl trimellitate, tris (2-ethylhexyl) trimellitate And the like. 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 Particularly preferred are benzyl phthalate having an alkyl group of -18, and trimellitic acid diester having an aliphatic alcohol residue of 3 to 5 carbon atoms such as dibutyl trimellitate and diisobutyl trimellitate. The aromatic carboxylic acid ester is preferably an aromatic di- or tricarboxylic acid ester.

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

(In formula (3), R ¹ and R ² are the same as described above. R ¹ and R ² may be the same or different.)

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

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

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

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

(In formula (5), R ¹ , R ² and R ³ are the same as described above. R ¹ and R ² may be the same or different.)
(5) Specific examples of oxyacid esters include triethyl acetylcitrate, tributyl acetylcitrate, and methyl acetylricinoleate.

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

(In formula (6), R ¹ , R ² and R ³ are the same as described above. R ¹ and R ² may be the same or different.)
(6) Specific examples of glycol esters include diethylene glycol dibenzoate, triethylene glycol di (2-ethylhexoate), and the like.

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

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

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

(In formula (8), R ¹ and R ² are the same as described above. R ¹ and R ² may be the same or different.)
(8) Specific examples of the sulfonamide include o- and p-toluenesulfonamide, N-butylbenzenesulfonamide and the like.

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

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

(Polymer particles)
In the present invention, polymer particles (vinyl polymer particles or polyester polymer particles) are used to improve printing density, glossiness, and image clarity by interaction with a water-insoluble organic compound.
The polymer of 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.
Moreover, the calculation method of the LogP value of a polymer is performed as follows.
1. The LogP value of each monomer from which each structural unit constituting the polymer is derived is determined by the SRC's LOGKOW / KOWWIN Program. In addition, the polymer structure derived from a chain transfer agent and an initiator is excluded.
2. The Log P value of each monomer is multiplied by the molar ratio (M) of the structural unit derived from that monomer in the polymer chain to determine (Log P × M) of each monomer.
3. The LogP value of the polymer is calculated by adding all (LogP × M) of each monomer obtained in 2 above.
The salt-forming group-containing monomer is calculated based on the LogP value of the monomer before neutralization.
From the viewpoint of dispersion stability, the polymer particles are preferably vinyl polymer particles obtained by addition polymerization of vinyl monomers (vinyl compounds, vinylidene compounds, vinylene compounds).

(Vinyl polymer)
As the vinyl polymer, (a) a salt-forming group-containing monomer (hereinafter sometimes referred to as “(a) component”), (b) a macromer (hereinafter sometimes referred to as “(b) component”) and / or (c ) A water-insoluble vinyl polymer obtained by copolymerizing a monomer mixture (hereinafter also referred to as “monomer mixture”) containing a hydrophobic monomer (hereinafter also referred to as “component (c)”) is preferable. This water-insoluble vinyl polymer has a structural unit derived from the component (a), a structural unit derived from the component (b) and / or a structural unit derived from the component (c).

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

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

(B) The macromer is used from the viewpoint of enhancing the dispersion stability of the polymer particles, particularly when the polymer particles contain a colorant. The macromer includes a macromer which is a monomer having a polymerizable unsaturated group having a number average molecular weight of 500 to 100,000, preferably 1,000 to 10,000. In addition, the number average molecular weight of (b) macromer is measured using polystyrene as a standard substance by gel chromatography using 1 mmol / L dodecyldimethylamine-containing chloroform as a solvent.
Among (b) macromers, styrenic macromers and aromatic group-containing (meth) acrylate macromers having a polymerizable functional group at one end are preferred from the viewpoint of dispersion stability of polymer particles.
Examples of the styrenic macromer include a styrene monomer homopolymer or a copolymer of a styrene monomer and another monomer. Examples of the styrene monomer include styrene, 2-methylstyrene, vinyl toluene, ethyl vinyl benzene, vinyl naphthalene, chlorostyrene, and the like.
Examples of the aromatic group-containing (meth) acrylate-based macromer include a homopolymer of an aromatic group-containing (meth) acrylate or a copolymer thereof with another monomer. As an aromatic group-containing (meth) acrylate, an arylalkyl having 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably 7 to 12 carbon atoms, which may have a substituent containing a hetero atom. (Meth) acrylate having an aryl group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a group or a substituent containing a hetero atom In addition, examples of the substituent containing a hetero atom include a halogen atom, an ester group, an ether group, and a hydroxy group. Examples include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, and benzyl (meth) acrylate is particularly preferable.
The polymerizable functional group present at one end of the macromer is preferably an acryloyloxy group or a methacryloyloxy group, and the other monomer to be copolymerized is preferably acrylonitrile.
The content of the styrene monomer in the styrene macromer or the aromatic group-containing (meth) acrylate in the aromatic group-containing (meth) acrylate macromer is preferably 50% by weight from the viewpoint of increasing the affinity with the pigment. Above, more preferably 70% by weight or more.

(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 (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).
Examples of commercially available styrenic macromers as component (b) include Toa Gosei Co., Ltd. trade names, AS-6 (S), AN-6 (S), HS-6 (S), and the like. It is done.

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

The aromatic group-containing monomer has an aromatic group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a substituent containing a hetero atom. Vinyl monomers are preferable, and examples thereof include the styrene monomer (c-1 component) and the aromatic group-containing (meth) acrylate (c-2 component). The above-mentioned thing is mentioned as a substituent containing a hetero atom.
Among the components (c), styrenic monomers (component c-1) are preferred from the viewpoint of improving glossiness and printing density. Examples of the styrenic monomers include those described above, and particularly styrene and 2-methylstyrene. preferable. The content of the component (c-1) in the component (c) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving printing density and glossiness.

  In addition, examples of the aromatic group-containing (meth) acrylate (c-2) component include those described above, and benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and the like are preferable. The content of the component (c-2) in the component (c) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving glossiness. Moreover, it is also preferable to use (c-1) component and (c-2) component together.

The monomer mixture may further contain (d) a hydroxyl group-containing monomer (hereinafter sometimes referred to as “component (d)”). (D) The hydroxyl group-containing monomer exhibits an excellent effect of enhancing dispersion stability.
As the component (d), for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, polyethylene glycol (n = 2 to 30, n represents the average number of added moles of oxyalkylene group. The same)) (meth) acrylate, polypropylene glycol (n = 2-30) (meth) acrylate, poly (ethylene glycol (n = 1-15) / propylene glycol (n = 1-15)) (meth) acrylate, etc. Can be mentioned. Among these, 2-hydroxyethyl (meth) acrylate, polyethylene glycol monomethacrylate, and polypropylene glycol methacrylate are preferable.

The monomer mixture may further contain (e) a monomer represented by the following formula (11) (hereinafter also referred to as “(e) component”).
^{_{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 (e) exhibits an excellent effect of improving the printing density, glossiness, and image clarity of the ink.
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 (e) include methoxypolyethylene glycol (1 to 30: the value of p in the formula (11), the same applies hereinafter) (meth) acrylate, methoxypolytetramethylene glycol (1 to 30) ( (Meth) acrylate, ethoxy polyethylene glycol (1-30) (meth) acrylate, octoxy polyethylene glycol (1-30) (meth) acrylate, polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether, (iso) Propoxypolyethylene glycol (1-30) (meth) acrylate, butoxypolyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Copolymerization) (1-30, ethylene glycol therein: 1-29) (meth) acrylate. Among these, octoxypolyethylene glycol (1-30) (meth) acrylate and polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether are preferable.

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

The content of the components (a) to (e) in the monomer mixture (content as an unneutralized amount; the same applies hereinafter) or the water-insoluble polymer (a) to (e) Content of the structural unit derived from a component is as follows.
The content of component (a) is preferably 2 to 40% by weight, more preferably 2 to 30% by weight, and particularly preferably 3 to 20% by weight from the viewpoint of dispersion stability of the resulting dispersion.
The content of the component (b) is preferably 1 to 25% by weight, more preferably 5 to 20% by weight, particularly from the viewpoint of enhancing the interaction with the colorant.
The content of the component (c) is preferably 5 to 98% by weight, more preferably 10 to 60% by weight from the viewpoints of glossiness and image clarity.
The content of component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The content of component (e) is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The total content of [component (a) + component (d)] in the monomer mixture is preferably 6 to 60% by weight, more preferably 10 to 50% by weight, from the viewpoint of dispersion stability of the resulting dispersion. is there. The total content of [component (a) + component (e)] is preferably 6 to 75% by weight, more preferably 13 to 50% by weight, from the viewpoint of dispersion stability of the resulting dispersion. Further, the total content of [(a) component + (d) component + (e) component] is preferably 6 to 60% by weight, more preferably 7 to 50% from the viewpoint of dispersion stability of the resulting dispersion. % By weight.
Further, the weight ratio of [(a) component / [(b) component + (c) component]] is preferably 0.01 to 1, more preferably 0.02 to 0 from the viewpoints of glossiness and image clarity. .67, more preferably 0.03 to 0.50.

(Manufacture of vinyl polymer)
The vinyl polymer used in the present invention is produced by copolymerizing a monomer mixture by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable.
The solvent used in the solution polymerization method is not particularly limited, but a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and the like. Among these, methanol, ethanol, acetone, methyl ethyl ketone, or a mixed solvent of one or more of these and water is preferable.
In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), t-butyl peroxyoctate, dibenzoyl oxide, etc. Known radical polymerization initiators such as organic peroxides can be used.
The amount of the radical polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture.
In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol and thiuram disulfide may be further added.

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

The weight average molecular weight of the polymer used in the present invention is preferably from 5,000 to 500,000, more preferably from 10,000 to 400,000, from the viewpoints of dispersion stability of the colorant, water resistance and dischargeability. 000 to 300,000 is particularly preferred.
In addition, the weight average molecular weight of a polymer is measured using polystyrene as a standard substance by gel chromatography using dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent.

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

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

(Polyester polymer)
In the present invention, water-dispersible polyester polymer particles are preferable as the polyester polymer particles from the viewpoint of dispersion stability of the polymer particles. As the water-dispersible polyester polymer particles, a self-dispersion type in which a hydrophilic group such as a carboxy group is introduced and neutralized as necessary is more preferable in order to stably disperse the polyester skeleton in water.
The polyester is obtained by polycondensation of an arbitrary diol compound and a dicarboxylic acid compound. At this time, in order to obtain suitable inkjet suitability, compounds such as monool, triol compound, monocarboxylic acid, tricarboxylic acid, and tetracarboxylic acid can also be used.
The diol compound or dicarboxylic acid compound may have an arbitrary functional group such as a hydrocarbon group, a carbonyl group, an ester group, or an ether group, which may have a ring structure having 1 to 22 carbon atoms. .

Examples of the diol compound used as a raw material for polyester include ethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, bisphenol A and The alkylene oxide adduct, hydrogenated bisphenol A and its alkylene oxide adduct, cyclohexanedimethanol and its alkylene oxide adduct, polyester diol, polyurethane diol, bishydroxymethylpropionic acid, bishydroxymethylbutyric acid and the like can be mentioned. In these, a C2-C30, especially C2-C22 diol compound is preferable.
Examples of the dicarboxylic acid compound used as a raw material for polyester include adipic acid, sebacic acid, fumaric acid, maleic acid and its anhydride, phthalic acid and its anhydride, trimellitic acid and its anhydride. Preferably it is C2-C22, More preferably, it is C4-C22 dicarboxylic acid compound or its anhydride.
Although there is no restriction | limiting in the molecular weight of polyester, Preferably it is 500-100,000, More preferably, it is 1,000-50,000, Most preferably, it is 2,000-30,000. The weight average molecular weight of the polyester is measured by the same method as described above. Polyester can be manufactured by a conventional method.

(Colorant (B))
The colorant (B) is used to exhibit the effects of glossiness and image clarity of the present invention. The colorant (B) is not particularly limited, and pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.) can be used, but water resistance, dispersion stability, and scratch resistance. In view of the above, pigments and hydrophobic dyes are preferred. Among them, it is preferable to use a pigment in order to express the high weather resistance which has been recently demanded.
When the pigment and the hydrophobic dye are used in an aqueous ink, it is necessary to use a surfactant and a polymer to form fine particles that are stable in the ink. In particular, from the viewpoints of bleeding resistance, water resistance, and the like, it is preferable to include a pigment and / or a hydrophobic dye in the polymer particles.
The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments.
Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Of these, carbon black is preferred particularly for black aqueous inks. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.
Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthoraquinone pigments, and quinophthalone pigments.
Specific examples of preferred organic pigments include C.I. I. Pigment yellow, C.I. I. Pigment Red, C.I. I. Pigment violet, C.I. I. Pigment blue, and C.I. I. One or more types of products selected from the group consisting of pigment green are listed.
Examples of extender pigments include silica, calcium carbonate, and talc.

The hydrophobic dye 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.
Examples of disperse dyes include C.I. I. Disperse Yellow, C.I. I. Disperse Orange, C.I. I. Disperse Red, C.I. I. Dispers Violet, C.I. I. Disperse Blue, C.I. I. One or more types of products selected from the group consisting of Disperse Green are listed. Of these, C.I. I. Solvent Yellow 29 and 30, C.I. I. Solvent Blue 70, C.I. I. Solvent Red 18 and 49, C.I. I. Solvent blacks 3 and 7 and nigrosine-based black dyes are preferred.
Among these, a chromatic colorant is preferable in order to exhibit the effects of glossiness and image clarity of the present invention. 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.

(Water dispersion / water-based ink)
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 (A) is preferably 0.11% by weight or more, more preferably 0.15% by weight or more, and particularly preferably 0. 0% from the viewpoint of improving image clarity and gloss. 2% by weight or more, 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. It is. From these viewpoints, the content of the water-insoluble organic compound (A) is preferably 0.11 to 10% by weight, more preferably 0.15 to 5% by weight, particularly preferably 0.2 to 3% by weight, 0 0.5-2% by weight is most preferred.
The content of the polymer particles (the solid content excluding the water-insoluble organic compound and the colorant. The same shall apply hereinafter) is preferably 0.5 to 30% by weight from the viewpoint of printing density, image clarity and gloss, and preferably 1 to 20%. % By weight is more preferable, and 1 to 15% by weight is particularly preferable.
The content of the colorant (B) 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 (A) / polymer particles] is preferably from 1/100 to 5/1, more preferably from 1/50 to 2/1, from the viewpoint of improving glossiness and image clarity. / 50 to 1/1 is more preferable, 1/30 to 1/1 is particularly preferable, and 1/10 to 1/1 is most preferable.
The weight ratio of [water-insoluble organic compound (A) / colorant (B)] is preferably 1/40 to 5/1, and preferably 1/30 to 1/1 from the viewpoint of image clarity and gloss. More preferably it is.
The weight ratio of [polymer particles / colorant (B)] is preferably 5/95 to 90/10, more preferably 10/90 to 75/25, from the viewpoint of dispersion stability of the polymer particles. 20/80 to 50/50 are particularly preferable.

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 with a colorant as a main solvent, and the water-based ink is ink using water as a main solvent.
The surface tension (20 ° C.) of the aqueous dispersion of the present invention is preferably 30 to 65 mN / m, more preferably 35 to 60 mN / m. Further, the surface tension (25 ° C.) of the water-based ink is preferably 20 to 35 mN / m, and more preferably 25 to 35 mN / m, from the viewpoint of securing good dischargeability from the ink nozzle.
The aqueous ink of the present invention has an ink contact angle of 15 to 60 ° after 1 second when ink is ejected onto inkjet photographic paper under the conditions of a dropping nozzle inner diameter of 30 μm and a dropping amount of 1 nl. Is preferable, and it is still more preferable that it is 25-50 degrees. Accordingly, it is considered that the glossiness and the image clarity are improved because it is possible to control the permeability of the ink into the recording medium and to secure the time for improving the affinity (fusion property) between the polymer particles in the water-based ink. Normally, when the surface tension of the ink is low, the permeability to the recording medium is high. However, since the water-based ink of the present invention contains a water-insoluble organic compound, it is considered that the contact angle can be controlled as described above.
The viscosity (20 ° C.) of 10% by weight of the aqueous dispersion of the present invention is preferably 2 to 6 mPa · s, and more preferably 2 to 5 mPa · s in order to obtain a preferable viscosity when an aqueous ink is used. In addition, the viscosity (20 ° C.) of the water-based ink of the present invention is preferably 2 to 12 mPa · s, and more preferably 2.5 to 10 mPa · s in order to maintain good ejection properties.

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 (A) is contained in the polymer particles by mixing with an aqueous dispersion of polymer particles and stirring appropriately. Part of the water-insoluble organic compound (A) may be present in addition to the polymer particles.
When the colorant (B) is a hydrophobic dye or pigment, it is preferable that the hydrophobic dye or pigment is contained in water-insoluble polymer particles from the viewpoint of dispersion stability and scratch resistance.

Such an aqueous dispersion can be obtained, for example, by the following steps (1) to (3).
Step (1): Step of obtaining a mixture containing a water-insoluble polymer, an organic solvent, a colorant, water, and if necessary, a neutralizing agent Step (2): The mixture obtained in Step (1) is subjected to a dispersion treatment, Step of obtaining a dispersion of water-insoluble polymer particles containing a colorant Step (3): Step (2) The organic solvent is removed from the obtained dispersion to disperse water-insoluble polymer particles containing a colorant in water. Step of obtaining body In step (1), first, the water-insoluble polymer is dissolved in an organic solvent, and then a colorant, water, and, if necessary, a neutralizing agent, a surfactant and the like, are obtained. A method of adding to the solution and mixing to obtain an oil-in-water dispersion is preferred. In the mixture, the colorant is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, the organic solvent is preferably 10 to 70% by weight, more preferably 10 to 50% by weight, and the water-insoluble polymer is The amount is preferably 2 to 40% by weight, more preferably 3 to 20% by weight, and water is preferably 10 to 70% by weight, more preferably 20 to 70% by weight.
When the water-insoluble polymer has a salt-forming group, it is preferable to use a neutralizing agent, 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 water-insoluble polymer. Examples of the neutralizing agent include those described above. Further, the water-insoluble polymer may be neutralized in advance.

  Examples of the organic solvent include alcohol solvents such as ethanol, isopropanol and isobutanol, ketone solvents such as acetone, methyl ethyl ketone and diethyl ketone, and ether solvents such as dibutyl ether, tetrahydrofuran and dioxane. The solubility in water is preferably 50% by weight or less and 10% by weight or more at 20 ° C., and methyl ethyl ketone is particularly preferable.

There is no restriction | limiting in particular in the dispersion method of the mixture in the said process (2). Although the average particle size of the polymer particles can be atomized only by the main dispersion until the desired particle size is reached, it is preferably pre-dispersed and then subjected to further dispersion by applying a shear stress to obtain the average particle size of the polymer particles. It is preferable to control the diameter to a desired particle diameter. 5-50 degreeC is preferable and, 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 devices, Ultra Disper [Asada Steel Co., Ltd., trade name], Ebara Milder [Ebara Seisakusho Co., Ltd., trade name], TK Homomixer, TK Pipeline Mixer, TK Homojetter, TK Homomic Line Flow, High-speed agitating and mixing devices such as Filmix [Special Machine Industry Co., Ltd., trade name], Clear Mix [M Technique Co., Ltd., trade name], KD Mill [Kinetic Dispersion Co., Ltd., trade name] and the like are preferable.
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) Representative homo-valve type high-pressure homogenizer, microfluidizer (Microfluidics, trade name), nanomizer (Nanomizer, trade name), optimizer (Sugino machine, trade name), Genus PY (Shiramizu Chemical Co., Ltd.) Product name], DeBEE2000 [Japan EE Co., Ltd., product name] and the like chamber type high-pressure homogenizer. 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 (3), an aqueous dispersion of polymer particles containing a colorant can be obtained by distilling off the organic solvent from the obtained dispersion by a known method to form an aqueous system. The organic solvent in the aqueous dispersion containing the resulting polymer particles is substantially removed. The amount of the residual organic solvent is preferably 0.1% by weight or less, and more preferably 0.01% by weight or less.
The obtained aqueous dispersion of polymer particles containing the colorant (B) is one in which the solid content of the polymer containing the colorant is dispersed in water as the main solvent. Here, the form of the polymer particles is not particularly limited as long as the particles are formed of at least a colorant and a polymer. For example, a particle form in which a colorant is included in a polymer, a particle form in which a colorant is uniformly dispersed in a polymer, a particle form in which a colorant is exposed on the surface of a polymer particle, and the like are included.

The aqueous dispersion for inkjet recording of the present invention comprises the steps (1) to (3), and the water-insoluble organic compound (A) is added during or after at least any of the steps (1) to (3). It can be obtained by making it exist.
For example, in step (1), a water-insoluble organic compound, a water-insoluble polymer, an organic solvent, a colorant, water, and, if necessary, a neutralizing agent are mixed during the production of the mixture. The content of the water-insoluble organic compound is preferably 1 to 40% by weight, more preferably 1 to 20% by weight in the mixture. The content of other components is as described above. The mixing temperature is preferably about 5 to 50 ° C. Other than that, the water dispersion of this invention can be obtained on the same conditions as the above-mentioned process (1)-(3). Alternatively, a water-insoluble organic compound may be mixed with a mixture containing a water-insoluble polymer, an organic solvent, a colorant, water, and, if necessary, a neutralizing agent. The water-insoluble organic compound is preferably 1 to 40 parts by weight and more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the mixture.
In step (2), a water-insoluble organic compound may be added or mixed during the dispersion treatment. The mixing ratio of the water-insoluble organic compound is preferably 1 to 40 parts by weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the mixture. Alternatively, after the dispersion treatment, the obtained dispersion and the water-insoluble organic compound may be mixed. The mixing ratio of the dispersion and the water-insoluble organic compound is preferably 1 to 40 parts by weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the dispersion. The mixing temperature is preferably about 5 to 50 ° C. Other than that, the water dispersion of this invention can be obtained on the same conditions as the above-mentioned process (1)-(3).
While removing the organic solvent in step (3), the water-insoluble organic compound (A) may be added or mixed. Preferably, the polymer particles containing the colorant obtained in step (3) What is obtained by mixing an aqueous dispersion and a water-insoluble organic compound (A) is preferable.

The mixing ratio of the aqueous dispersion of polymer particles containing the colorant (B) and the water-insoluble organic compound (A) is 100 parts by weight of the solid content of the aqueous dispersion of polymer particles containing the colorant (B). The water-insoluble organic compound (A) is preferably 1 to 100 parts by weight, preferably 3 to 50 parts by weight, and more preferably 3 to 20 parts by weight. The mixing method may add the water-insoluble organic compound (A) to the aqueous dispersion of polymer particles containing the colorant (B), or vice versa. The mixing temperature is preferably about 5 to 50 ° C.
Among the above production methods, a method in which the water-insoluble organic compound (A) is present in the aqueous dispersion obtained in the step (3) is particularly preferable. Specifically, the water-insoluble organic compound (A) is added to or mixed with the aqueous dispersion of polymer particles containing the colorant (B) obtained in the step (3).
The obtained aqueous dispersion is an aqueous dispersion of water-insoluble polymer particles containing the water-insoluble organic compound (A) and the colorant (B).

The aqueous dispersion of polymer particles 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, and a rust preventive agent that are usually used in aqueous inks for inkjet recording. Etc. 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 0.03 to 0.5 from the viewpoint of preventing clogging of the nozzles of the printer and dispersion stability. It is 0.3 μm, particularly 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%.
In addition, even if the water-insoluble organic compound (A) and / or the colorant (B) is further contained in the polymer particles, the average particle diameter of the polymer particles is preferably the same as described above.

(Water-based ink with a correlation distance of 4 μm or more)
The present invention is also a water-based ink for ink-jet recording containing an aqueous dispersion of a pigment, wherein the water-based ink has a pigment concentration of 4 to 8% by weight, and has an ink size of 3 pl and a resolution of 1440 dpi × The solid correlation (100% duty fill printing) is performed at 720 dpi, and the correlation distance in the vertical direction with respect to the print direction of the reflected light amount when the laser beam is irradiated from the vertical direction on the print surface is 4 μm or more. It is a water-based ink for inkjet recording.
The aqueous dispersion of the pigment is preferably polymer particles containing the pigment, more preferably a water-insoluble organic compound is contained in the water-based ink, and the water-insoluble organic compound is a polymer containing the pigment. It is preferable to be contained in the particles.
The polymer particles, the water-insoluble organic compound, the pigment, and their quantitative relationship are the same as described above.

The direction perpendicular to the printing direction is the direction perpendicular to the direction of movement of the head of the inkjet printer, and is the same direction as the paper feed direction. “Correlation distance perpendicular to the print direction of the amount of light reflected when laser light is irradiated from the perpendicular direction to the print surface” means that the laser is perpendicular to the print surface, that is, directly above the print surface. Irradiate light to measure the amount of reflected light in a minute area to obtain its distribution, calculate the autocorrelation function when moved in the direction perpendicular to the printing direction, and calculate the autocorrelation function R (a) Is a distance of 1 / e.
The autocorrelation function R (a) is calculated as follows.
First, the distribution of the amount of reflected light when laser light is irradiated from the direction perpendicular to the print surface is measured. Next, _let F _ij be the amount of reflected light at the i-th pixel in the printing direction (the direction in which the printer head moves) and the j-th pixel in the printing direction. Using a part of the obtained reflected light amount distribution data, an autocorrelation function R (a) in the direction perpendicular to the printing direction is obtained by the following equation.
The following formula for obtaining the autocorrelation function R (a) is a reference document of “11 high-definition color digital standard image data ISO / JIS-SCID JIS X9201-1995 technical explanation” (Japanese Standards Association 1995), page 32. The equation is rewritten when the distance a is moved only in the direction perpendicular to the printing direction. Also, the numerical values of Σ256 and 640 were used as numbers sufficient to obtain data.

The correlation distance (the distance at which the autocorrelation function R (a) value is 1 / e) is 4 μm or more, preferably 5 μm or more. Although there is no upper limit in particular, 20 micrometers or less may be sufficient.
In order for the autocorrelation function R (a) value to be regarded as 0, a distance of 2 to 3 times the correlation distance is necessary, and the correlation distance of 4 μm means that the distance is about 10 μm. This corresponds to the radius (about 10 μm) of one dot of 3 pl ink ejected from the nozzle. A correlation distance of 4 μm or more means that the amount of reflected light has a correlation at a point about 10 μm away. Therefore, this means that the smooth surface is spread to be equal to or larger than the size of one dot, so that it is considered that the glossiness and image clarity are improved even if dots overlap each other during printing.

In a printer incorporating an MSDT (multi-size dot technology) function, the minimum ink size corresponds to the ink size here. If this is 3 pl, the correlation distance can be similarly evaluated by a printer having the MSDT function.
On the other hand, if the pigment concentration is too low, the glossiness and image clarity are improved, but the print density is lowered. Therefore, in order to satisfy the print density, glossiness, and image clarity, the pigment content is 4 in the water-based ink. -8 wt% is preferable, and 5-7 wt% is more preferable.
The inkjet photographic paper used in the present invention is a void-type glossy medium having a 60 ° gloss of 35 or more and 45 or less. Here, the glossiness is a value measured by a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: HANDY GLOSSMETER, product number: PG-1). Such photographic paper is commercially available, and a preferred example is Seiko Epson Corporation, trade name: KA450PSK.

  The ink jet method to which the water-based ink of the present invention is applied is not limited, but is particularly suitable for a piezo ink jet printer.

In the following production examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified.
Production Examples 1 to 4 (Production of polymer)
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.
(B) Styrene macromer (Log P value = 165.72)
Toa Gosei Co., Ltd., trade name: AS-6 (S), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group (d) M-90G (Log P value = −0.89)
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
(D) PP-500 (Log P value = 2.25)
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 9, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMMER PP-500
(D) PP-800 (Log P value = 2.67)
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) 50POEP-800B (LogP value = 3.32)
Octoxy polyethylene glycol polypropylene glycol monomethacrylate (ethylene oxide average addition mole number = 8, propylene oxide average addition mole number = 6, terminal: 2-ethylhexyl group): manufactured by NOF Corporation, trade name: BLEMMER 50POEP-800B

The LogP value of the polymer synthesized in Production Example 1 (methacrylic acid / benzyl methacrylate / styrene macromer / styrene / M-90G / PP-500 = 10 parts / 40 parts / 15 parts / 10 parts / 5 parts / 20 parts) The calculation method is as follows.
The LogP value of methacrylic acid is 0.99 (Mw: 86), the LogP value of benzyl methacrylate is 2.98 (Mw: 176), the LogP value of styrene is 2.89 (Mw: 104), and the styrene macromer is Since about 57 mol of styrene is added to the basic structure of methacrylic acid, its LogP value is 165.72 (= 0.99 + 57 × 2.89).
M-90G:
Polyethylene glycol monomethacrylate (average number of moles of ethylene oxide added = 9): It has a methacryloyloxy group, 9 moles of ethylene oxide are added, and the terminal is a methyl group. It has 9 moles of oxide. Since the log P value of ethylene oxide is −0.27 and the log P value of methacrylic acid is 0.99, the log P value of M-90G is −0.89 (= 0.99−0.27 × 9 + 0. 55, Mw: 496).
PP-500:
Polypropylene glycol monomethacrylate (propylene oxide average addition mole number = 9): It has a methacryloyloxy group, 9 mol of propylene oxide is added, and the terminal is a hydrogen atom. It has 9 moles of propylene oxide. Since the LogP value of propylene oxide is 0.14 and the LogP value of methacrylic acid is 0.99, the LogP value of PP-500 is 2.25 (= 0.99 + 0.14 × 9, Mw: 608). Is calculated.
Therefore, since the LogP value of the polymer is the sum of the values obtained by multiplying the LogP value of each monomer by each mol%, (10/86 + 15/6000 + 40/176 + 10/104 + 5/496 + 20/608) = 0.485. Therefore, 3.20 [= 0.99 × 10/86 / 0.485 + 2.98 × 40/176 / 0.485 + 165.72 × 15/6000 / 0.485 + 2.89 × 10/104 / 0.485-0 .89 × 5/496 / 0.485 + 2.25 × 20/608 / 0.485].
Similarly to the polymer of Production Example 1, the LogP values of the polymers of Production Examples 2 to 4 were obtained. The results are shown in Table 1.

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 4.1 parts of neutralizing agent (5N aqueous sodium hydroxide solution) was contained therein (degree of neutralization 60%). ) And 230 parts of ion-exchanged water to neutralize the salt-forming group, and further add 75 parts of quinacridone pigment (CI Pigment Violet 19, Clariant Japan Co., Ltd., trade name: Hostaperm Red E5B02), with a disper blade at 20 ° C. For 1 hour. The obtained mixture was 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: Pigment-containing vinyl polymer particles having a solid content concentration of 20% by filtering with a 25 mL needleless syringe (made by Terumo Co., Ltd.) attached with 2.5 cm, manufactured by Fuji Photo Film Co., Ltd., and removing coarse particles An aqueous dispersion was obtained.
40 parts of an aqueous dispersion of the obtained pigment-containing vinyl polymer particles and 1 part of tricresyl phosphate (Log P value = 4.90) are mixed and stirred to at least partially add tricresyl phosphate in the polymer particles. Contained. In this mixed solution, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), 0.3 part of Proxel XL2 (manufactured by Avicia Corporation) and ion exchange 40.7 parts of water was mixed, and the resulting mixture was filtered with a 25 mL needleless syringe equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.). Then, by removing coarse particles, water-based inks shown in Table 2 were obtained.

Example 2
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 12.5 parts of tricresyl phosphate, neutralizer (5N aqueous sodium hydroxide solution) 4 0.1 part (neutralization degree 60%) and 230 parts of ion-exchanged water were added to neutralize the salt-forming group, and quinacridone pigment (CI Pigment Violet 19, Clariant Japan, trade name: Hostaperm Red E5B02) 75 The mixture was added and mixed with a disper blade at 20 ° C. for 1 hour. The obtained mixture was 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: A solid content concentration (including tricresyl phosphate) is obtained by filtering with a 25 mL needleless syringe (made by Terumo Corporation) with a 2.5 cm attached Fuji Photo Film Co., Ltd. and removing coarse particles. An aqueous dispersion of 22.5% pigment-containing vinyl polymer particles was obtained.
40 parts of an aqueous dispersion of the obtained pigment-containing vinyl polymer particles, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether (TEGMBE), 1 part of Surfinol 465, 0.3 part of Proxel XL2 and 41.7 parts of ion-exchanged water And the resulting mixture is filtered with a 25 mL needleless syringe equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) to remove coarse particles. The aqueous ink shown in Table 2 was obtained by removing.

Examples 3 and 4
In Example 1, instead of tricresyl phosphate, dibutyl phthalate (Log P value = 4.61) or dibutyl sebacate (Log P value = 6.30) was used, as in Example 1, and Table 2 The water-based ink shown in FIG.
Comparative Example 1
In Example 1, water-based inks shown in Table 2 were obtained in the same manner as in Example 1 except that tricresyl phosphate was not mixed and 41.7 parts of ion-exchanged water was mixed.
Comparative Examples 2 and 3
In Example 1, instead of tricresyl phosphate, butyl oleate (LogP value = 9.49) or 2-ethylhexyl palmitate (LogP value = 10.33) was used. A water-based ink shown in Table 2 was obtained.
The average particle diameter of the water dispersion was in the range of 0.05 to 0.2 μm in each of Examples 1 to 4 and Comparative Examples 1 to 3.

Next, the performances of the inks obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were measured according to the following method. The results are shown in Table 2.
(1) Printing density Using a printer (model number: EM-930C, piezo method) manufactured by Seiko Epson Corporation, solid printing on commercially available high-quality plain paper (trade name: KA4250NT, manufactured by Seiko Epson Corporation) [printing condition = paper Type: plain paper, mode setting: photo] and left at 25 ° C. for 24 hours, and the print density was measured 5 times with a Macbeth densitometer (product number: RD914), and the average value was obtained. The higher the value, the higher the print density.

(2) Glossiness Using the printer, solid printing was performed on commercially available dedicated paper (photographic paper <gloss> (60 ° glossiness: 41), manufactured by Seiko Epson Corporation, product name: KA450PSK) [printing condition = paper type: Photo print paper, mode setting: Photo], left at 25 ° C. for 24 hours, and then glossed at 20 ° with a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: HANDY GLOSSMETER, product number: PG-1) 5 times The average value was obtained by measurement. The larger the value, the higher the glossiness.

(3) Image clarity Using the printer, solid printing was performed on the special paper of (2) under the same conditions as in (2) above, and after standing at 25 ° C for 24 hours, the image clarity of 45 ° C (%) (comb width) 2.0 mm) was measured three times with an image clarity measuring device (manufactured by Suga Test Instruments Co., Ltd., trade name: touch panel type image clarity measuring device, product number: ICM-IT), and an average value was obtained.
The image clarity is to measure the sharpness or distortion when the image is reflected on the printed matter. When the numerical value is larger, the reflected image is clearer and less distorted, and the reflected image looks natural.

(4) Correlation Distance Measurement Method Using the printer, solid printing is performed on the dedicated paper of (2) under the same conditions as in (2) [100% duty fill printing. Ink size 3 pl, resolution 1440 dpi × 720 dpi. The ink discharge amount per unit area under this condition is 1.8 mg / cm ² . ] After leaving the obtained printed matter at 25 ° C. for 24 hours, the distribution of the amount of reflected light when irradiated with laser light from the perpendicular direction to the printing surface with an ultra-deep shape measuring microscope VK-8500 manufactured by Keyence Corporation It was measured.
In the measurement method, the printed matter was fixed to a slide glass with a double-sided tape, and the printing direction (direction in which the printer head moves) was set in the apparatus as a horizontal direction. The measurement conditions are as follows.
Laser: 685 nm (0.45 mW), objective lens 20 times, measurement area: 740 μm × 550 μm (1 pixel 0.728 μm × 0.728 μm for 1024 × 768 pixels)
From the obtained two-dimensional light quantity distribution, an autocorrelation function R (a) in the direction perpendicular to the printing direction was calculated by the method described above. Further, the distance at which the value becomes 1 / e was calculated from the plot of the autocorrelation function R (a), and the correlation distance perpendicular to the printing direction was found. In all of the measured samples, the autocorrelation function could be approximated by an exponential function in the range of 0 to 50 μm.
A plot of the autocorrelation function R (a) (Example 1 and Comparative Example 1) is shown in FIG.
From FIG. 1, it can be seen that the value at which the autocorrelation function R (a) is 1 / e is 5.0 μm in Example 1 and 2.5 μm in Comparative Example 1.

Examples 5-25
A water-based ink was obtained in the same manner as in Example 1, except that the water-insoluble organic compound shown in Table 3 was used instead of tricresyl phosphate.
Table 3 shows the results of Examples 5 to 25 together with the results of Examples 1 to 4.
FIG. 2 shows the relationship between the LogP value of the water-insoluble organic compounds obtained in Examples 1 to 25 and the 20 ° glossiness (the solid line is the 20 ° glossiness of Comparative Example 1), and FIG. 1 shows the relationship between the LogP value of the water-insoluble organic compound obtained in 1 to 25 and the 45 ° image clarity value (the solid line is the 45 ° image clarity value of Comparative Example 1).

  From the results shown in Tables 2 and 3 and FIGS. 2 and 3, all of the inks obtained in Examples 1 to 25 can impart high printing density to plain paper. It can be seen that excellent gloss and image clarity can be imparted.

Example 26
30 parts of the polymer obtained by drying the polymer solution obtained in Production Example 2 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and 5.4 parts of a neutralizing agent (5N aqueous sodium hydroxide solution) was contained therein. And 230 parts of ion-exchanged water are added to neutralize the salt-forming group, and quinacridone pigment (magenta: M) (CI Pigment Violet 19 [PV19], manufactured by Clariant Japan Co., Ltd.) Name: Hostaperm Red E5B02) 70 parts was added and mixed with a disper blade at 20 ° C. for 1 hour. The obtained mixture was 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: Pigment-containing vinyl polymer particles having a solid content concentration of 20% by filtering with a 25 mL needleless syringe (made by Terumo Co., Ltd.) attached with 2.5 cm, manufactured by Fuji Photo Film Co., Ltd., and removing coarse particles An aqueous dispersion was obtained.
40 parts of an aqueous dispersion of the obtained pigment-containing vinyl polymer particles and 1 part of dibutyl sebacate (LogP value = 6.30) are mixed and stirred to contain at least a part of dibutyl sebacate in the polymer particles. I let you. In this mixed solution, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether, 1 part of Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), 0.3 part of Proxel XL2 (manufactured by Avicia Co., Ltd.) and 40. 7 parts were mixed, and the obtained mixed solution was filtered with a needleless syringe with a capacity of 25 mL equipped with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.). By removing the particles, water-based inks shown in Table 4 were obtained.
The performance of the obtained water-based ink was measured according to the method described above. The results are shown in Table 4.

Example 27
35 parts of a polymer obtained by drying the polymer solution obtained in Production Example 3 under reduced pressure, and a diazo pigment (yellow: Y) (CI pigment yellow 74 [PYY74], Sanyo dye as a pigment) Co., Ltd., trade name: FY7413) 65 parts, neutralizing agent (5N aqueous sodium hydroxide solution) 7.5 parts The same procedure as in Production Example 1 was applied except that the neutralization degree was 60%. An aqueous dispersion of 20% pigment-containing vinyl polymer particles was obtained.
A water-based ink shown in Table 4 was obtained in the same manner as in Production Example 2 except that 43.07 parts of the obtained pigment-containing vinyl polymer particle aqueous dispersion and 37.63 parts of ion-exchanged water were used.
The performance of the obtained water-based ink was measured according to the method described above. The results are shown in Table 4.

Example 28
40 parts of a polymer obtained by drying the polymer solution obtained in Production Example 4 under reduced pressure, and a phthalocyanine pigment (cyan: C) (CI pigment blue 15: 4 [P.B. 15: 4], Toyo Manufactured by Ink Manufacturing Co., Ltd., trade name: LIONOGEN BLUE BGJ), neutralizing agent (5N sodium hydroxide aqueous solution) 8.6 parts, except that the neutralization degree was 60%. An aqueous dispersion of pigment-containing vinyl polymer particles having a solid content concentration of 20% was obtained.
A water-based ink shown in Table 4 was obtained in the same manner as in Production Example 2 except that 33.33 parts of the obtained pigment-containing vinyl polymer particle aqueous dispersion and 47.37 parts of ion-exchanged water were used.
The performance of the obtained water-based ink was measured according to the method described above. The results are shown in Table 4.

Examples 29-34
Except dibutyl sebacate mixed with the aqueous dispersion of pigment-containing vinyl polymer particles in the amount shown in Table 2, and adjusting the ion-exchanged water mixed with this mixed solution to make the total amount of aqueous ink 100 parts In the same manner as in Example 26 for magenta, Example 27 for yellow, and Example 28 for cyan, water-based inks shown in Table 4 were obtained.
The performance of the obtained water-based ink was measured according to the method described above. The results are shown in Table 4.
Examples 35-37
Aqueous inks shown in Table 4 were obtained in the same manner as in Examples 26 to 28 except that dibutyl sebacate was changed to octyl benzyl phthalate (Log P value = 6.79).
The performance of the obtained water-based ink was measured according to the method described above. The results are shown in Table 4.

Comparative Examples 4-6
A water-based ink shown in Table 5 was obtained in the same manner as in Examples 26 to 28 except that no water-insoluble organic compound was used.
The performance of the obtained water-based ink was measured according to the method described above. The results are shown in Table 5.

It is a plot figure of the autocorrelation function R (a) of the reflected light quantity obtained in Example 1 and Comparative Example 1. The solid lines show the results of fitting with the exponential function exp (-a / ξ). However, ξ is a constant and means a correlation distance. It is the figure showing the relationship between the LogP value of the water-insoluble organic compound obtained in Examples 1-25, and 20 degree glossiness. The thick line represents the 20 ° glossiness (35) of Comparative Example 1. It is a figure showing the relationship between the LogP value and 45 degree image clarity value of the water-insoluble organic compound obtained in Examples 1-25. The bold line represents the 45 ° image clarity value (20) of Comparative Example 1.

Claims (13)

  An aqueous dispersion for inkjet recording, comprising an aqueous dispersion of vinyl polymer particles or polyester polymer particles containing a colorant (B), and a water-insoluble organic compound (excluding a fatty acid derivative) (A).   The water-insoluble organic compound (A) has two or more ester or ether bonds in the molecule, the ester or ether compound (f), and / or one or more ester or ether bonds in the molecule, and a carboxy group The ester or ether compound (g) having at least one functional group selected from the group consisting of sulfonic acid group, phosphoric acid residue, carbonyl group, epoxy group and hydroxyl group. An aqueous dispersion for inkjet recording.   The water dispersion for inkjet recording according to claim 1 or 2, wherein the water-insoluble organic compound (A) is at least one selected from the group consisting of a phosphate ester, an aliphatic di- or tricarboxylic acid ester, and an aromatic carboxylic acid ester. .   The water dispersion according to any one of claims 1 to 3, wherein a part of the water-insoluble organic compound (A) is contained in vinyl polymer particles or polyester polymer particles.   The weight ratio of [water-insoluble organic compound (A) / vinyl polymer particles or polyester polymer particles] in the water dispersion is 1/100 to 5/1. Water dispersion for inkjet recording. The water dispersion for inkjet recording according to any one of claims 1 to 5, wherein the content of the water-insoluble organic compound (A) in the water dispersion is 0.11 to 10% by weight.   The water dispersion for inkjet recording according to any one of claims 1 to 6, wherein the water-insoluble organic compound (A) has a Log P value of -1 to 11.   The value of [[Log P value of water-insoluble organic compound (A)]-[Log P value of vinyl polymer or polyester polymer]] is -4 to 8, water for inkjet recording according to any one of claims 1 to 7. Dispersion.   9. The water-insoluble vinyl polymer obtained by copolymerizing a monomer mixture containing (a) a salt-forming group-containing monomer, (b) a macromer and / or (c) a hydrophobic monomer. The aqueous dispersion for inkjet recording as described.   A water-based ink for ink-jet recording, comprising the water dispersion according to claim 1.   A water-based ink for ink-jet recording containing an aqueous dispersion of a pigment, wherein the water-based ink has a pigment concentration of 4 to 8% by weight, and is solid-printed on ink-jet photographic paper at an ink size of 3 pl and a resolution of 1440 dpi × 720 dpi. A water-based ink for ink jet recording in which the correlation distance in the vertical direction with respect to the printing direction of the amount of light reflected when the laser beam is applied to the printing surface from the vertical direction is 4 μm or more.   The printed matter which printed the water-system ink of Claim 10 or 11 using the inkjet recording device. The following steps (1) to (3) are included, and a water-insoluble organic compound (excluding a fatty acid derivative) is allowed to exist during or after at least one of steps (1) to (3). The manufacturing method of the water dispersion for inkjet recording in any one of Claims 1-9.
Step (1): Step of obtaining a mixture containing a water-insoluble polymer, an organic solvent, a colorant, and water Step (2): Step of dispersing the mixture obtained in Step (1) Step (3): Step ( 2) Step of removing the organic solvent from the obtained dispersion to obtain an aqueous dispersion of water-insoluble polymer particles containing a colorant.

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