JP2008184616A - Ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set for inkjet recording which capable of exhibtiting a multi-order color or composite black having excellent glossiness and image clarity and to provide a method for producing a printed matter using the ink set. <P>SOLUTION: The ink set for inkjet recording comprises two or more inks having different colors, in which the ink comprises a water-insoluble organic compound (A), polymer particles (B), and a colorant (C). The method for producing a printed matter comprises using the ink set. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink set, and more specifically, an ink set for ink jet recording capable of obtaining a multi-color or the like having a high printing density, excellent glossiness and image clarity, and composite black, and the ink set are used. The present invention relates to a method for producing printed matter.

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, 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 formed by dissolving a water-insoluble resin in order to suppress color bleeding.
Patent Document 3 discloses an ink containing 10 to 1000 ppm of phthalic acid diester and latex in order to form a glossy image.
These inks have improved glossiness and the like to some extent, but more excellent performances such as glossiness and image clarity are required for multi-colors and composite blacks.

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

  The present invention provides an ink set for ink jet recording capable of obtaining a multi-color or composite black having a high printing density and excellent glossiness and image clarity, and a method for producing a printed matter using the ink set. Is an issue.

The present invention
(1) An ink set comprising two or more different color inks, wherein the ink is an ink containing a water-insoluble organic compound (A), polymer particles (B) and a colorant (C). Ink set for inkjet recording,
(2) An ink set including a magenta ink, a yellow ink, and a cyan ink, and two kinds of inks selected from the ink set are a water-insoluble organic compound (A), polymer particles (B), and a colorant (C An ink set for inkjet recording, wherein the other one is an ink that does not contain a water-insoluble organic compound,
(3) The ink set of (1) or (2) is an ink set including magenta ink, yellow ink, and cyan ink, and the ink of the ink set is printed on inkjet photographic paper by an inkjet recording method. And a method for producing a black printed matter with composite black, and (4) an ink jet photographic paper using two or more different color inks provided in the ink set of (1) or (2) by an ink jet recording method. Provided is a method for producing a multi-colored printed matter to be printed on.

The multi-color and composite black obtained by printing by the ink jet recording method using the ink set of the present invention give excellent glossiness and image clarity when printed on ink jet photographic paper.
Further, according to the method of the present invention, printed matter excellent in gloss and image clarity can be produced efficiently.

  The ink set of the present invention is an ink set for inkjet recording, which is an ink containing a water-insoluble organic compound (A), polymer particles (B), and a colorant (C), and inks of two or more different colors A combination of Hereinafter, each of these components will be described sequentially.

(Water-insoluble organic compound (A))
The water-insoluble organic compound (A) used in the present invention is a compound that imparts plasticity that can be contained at least in part in the polymer particles to improve the flexibility of the polymer particles. The water-insoluble organic compound (A) imparts flexibility to the polymer particles, so that the polymer particles in one ink ejected from the nozzle of the ink jet recording apparatus mutually melt with the polymer particles of the other ink on the recording paper. It is considered that the glossiness and image clarity of the obtained multi-colors and composite black prints (including printed matter, the same applies hereinafter) are improved.
The water-insoluble organic compound (A) 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 glossiness and image clarity of printed matter.
The amount of water-insoluble organic compound (A) 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 8. 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 the 1-octanol / water partition coefficient of water-insoluble organic compounds, calculated by the fragment approach by SRC's LOGKOW / KOWWIN Program of KowWin (Syracuse Research Corporation, USA). The KowWin Program methodology is described in the following journal article: Meylan, WM and PH Howard. 1995. Atom / fragment contribution method for using octanol-water partition coefficients. J. Pharm. Sci. 84: 83-92 .). The fragment approach is based on the chemical structure of the compound and takes into account the number of atoms and the type of chemical bond. The LogP value is a numerical value generally used for relative evaluation of the hydrophilicity / hydrophobicity of an organic compound. 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 ester or ether bonds in the molecule and at least one selected from the group consisting of a carboxy group, a sulfonic acid group, a phosphoric acid residue, a carbonyl group, an epoxy group and a hydroxyl group An ester or ether compound (g) having one or more functional groups 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 carboxylic acid ester is preferably an aliphatic di- or tricarboxylic acid ester from the viewpoint of image clarity. The aliphatic dicarboxylic acid ester is preferably a compound represented by the following formula (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 phthalates having 18 to 18 alkyl groups, and trimellitic acid diesters having aliphatic alcohol residues 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 (B))
In the present invention, the polymer particles (B) are used for improving printing density, glossiness, and image clarity by interaction with the water-insoluble organic compound (A).
This polymer is preferably a water-insoluble polymer in order to easily contain the water-insoluble organic compound (A). Here, the water-insoluble polymer means that when the polymer is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolution amount is 10 g or less, preferably 5 g or less, more preferably 1 g or less. Is a polymer. When the polymer has a salt-forming group, the dissolution amount is a dissolution amount when the salt-forming group of the polymer is neutralized 100% with acetic acid or sodium hydroxide according to 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.
Examples of the water-insoluble polymer particles include water-insoluble vinyl polymer particles, water-insoluble ester polymer particles, and water-insoluble urethane polymer particles. Among these, water-insoluble vinyl polymer particles obtained by addition polymerization of vinyl monomers (vinyl compounds, vinylidene compounds, vinylene compounds) are preferable from the viewpoint of dispersion stability as polymer particles.

(Water-insoluble polymer)
Examples of the water-insoluble polymer of the water-insoluble polymer particles include (a) a salt-forming group-containing monomer (hereinafter sometimes referred to as “component (a)”) and (b) a macromer (hereinafter referred to as “component (b)”). And / or (c) a water-insoluble polymer obtained by copolymerizing a monomer mixture (hereinafter sometimes referred to as “monomer mixture”) containing a hydrophobic monomer (hereinafter sometimes referred to as “component (c)”). . This water-insoluble polymer has a structural unit derived from the component (a), a structural unit derived from the component (b) and / or a structural unit derived from the component (c).

(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. As mentioned above, More preferably, it is 70 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.

As the aromatic group-containing monomer, a vinyl monomer having an aromatic group having 6 to 22 carbon atoms, preferably 6 to 12 carbon atoms, which may have a substituent containing a hetero atom, is preferable. Examples thereof include styrene monomers (c-1 component) and the above-mentioned aromatic group-containing (meth) acrylates (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) Propoxy polyethylene glycol (1-30) (meth) acrylate, butoxy polyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Copolymerization) (1-30, ethylene glycol therein: 1-29) (meth) acrylate. Among these, octoxypolyethylene glycol (1-30) (meth) acrylate and polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether are preferable.

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

Components (a) to (e) in the monomer mixture of the above components (a) to (e) at the time of production of the water-insoluble polymer (contents as an unneutralized amount; the same applies hereinafter) The content of the structural unit derived from 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 weight ratio ((a) / [(b) + (c)]) of the components (a), (b) and (c) in the water-insoluble polymer is preferably from the viewpoint of glossiness and image clarity. It is 01 to 1, more preferably 0.02 to 0.67, still more preferably 0.03 to 0.50.
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.

(Manufacture of polymers)
The polymer used in the present invention is produced by copolymerizing a monomer mixture by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable.
The solvent used in the solution polymerization method is not particularly limited, but a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones such as acetone 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 obtained as described above 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 water-insoluble polymer used in the present invention has a salt-forming group derived from (a) 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, dimethyl Examples include bases such as amine, 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, the degree of neutralization can be determined by the following formula.
[[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine value of polymer (HCL mg / g) × weight of polymer (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 a suitable solvent (for example, methyl ethyl ketone) and titrated.

(Colorant (C))
The colorant (C) is used to exhibit the effects of glossiness and image clarity of the present invention. The colorant (C) 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 develop the high weather resistance which has been demanded in recent years.
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 viewpoint of bleeding resistance, water resistance and the like, it is preferable to include a pigment and / or a hydrophobic dye in the polymer particles.
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, C.I. I. Examples are products of various product numbers such as Solvent Orange, which are commercially available from Orient Chemical Co., Ltd., BASF Co., etc.
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.

(ink)
The ink constituting the ink set of the present invention contains a water-insoluble organic compound (A), polymer particles (B), and a colorant (C).
In the ink of the present invention, 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, particularly from the viewpoint of image clarity and gloss. Preferably it is 0.2% 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, most preferably 2% by weight or less. Accordingly, the content of the water-insoluble organic compound (A) is preferably from 0.11 to 10% by weight, more preferably from 0.15 to 5% by weight, and from 0.2 to 3% by weight from the viewpoint of image clarity and gloss. % Is particularly preferable, and 0.5 to 2% by weight is most preferable.
In the ink of the present invention, the content of the polymer particles (B) (solid content excluding water-insoluble organic compound and colorant; the same shall apply hereinafter) is preferably from the viewpoint of printing density, image clarity and glossiness. It is 5 to 30% by weight, more preferably 1 to 20% by weight, and particularly preferably 1 to 15% by weight.
In the ink of the present invention, the content of the colorant (C) 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 particle (B)] 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. Preferably, 1/50 to 1/1 is more preferable, 1/30 to 1/1 is particularly preferable, and 1/10 to 1/1 is most preferable.
The weight ratio of [water-insoluble organic compound (A) / colorant (C)] is preferably 1/40 to 5/1, and more preferably 1/30 to 1/1, from the viewpoints of glossiness and image clarity.
The weight ratio of [polymer particle (B) / colorant (C)] is preferably 5/95 to 90/10 from the viewpoint of dispersion stability of the polymer particles, and preferably 10/90 to 75/25. Is more preferable, and 20/80 to 50/50 is particularly preferable.

The ink of the present invention is a water-based ink using water as a main solvent. The water content in the ink is preferably 30 to 90% by weight, more preferably 40 to 80% by weight.
The surface tension (25 ° C.) of the ink of the present invention 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.
In addition, the ink of the present invention may have a 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. Preferably, the angle is 25 to 50 °. Accordingly, it is considered that the glossiness and the image clarity are improved because it is possible to control the penetrability of the ink into the recording medium and secure the time for improving the affinity (fusion property) between the polymer particles in the ink. Usually, when the surface tension of the ink is low, the permeability to the recording medium is high. However, since the ink of the present invention contains a water-insoluble organic compound, it is considered that the contact angle can be controlled as described above.
In addition, the viscosity (25 ° C.) of the 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 dischargeability.

The ink jet photographic paper used in the present invention is provided with a porous ink absorbing layer containing inorganic fine particles on a support, specifically, porous inorganic particles such as alumina and silica and water-soluble. A medium having a void-type ink receiving layer composed of a resin (binder) is a void-type glossy medium having a support including paper, a resin film, and a composite thereof. The 60 ° glossiness of the inkjet photographic paper is preferably 35 or more and 45 or less.
Such void-type glossy media are known, and are described, for example, on pages 174 to 181 of “Applications and Materials of Inkjet Printers” (CMC Corporation, issued in 2002).
Examples of such inkjet photographic paper include Seiko Epson Corporation, trade name: photographic paper <glossy>, model number: KA450PSK.

There is no limitation in particular in the manufacturing method of the ink of this invention. For example, the water-insoluble organic compound (A) is contained in the polymer particles (B) by mixing with an aqueous dispersion of the polymer particles (B) and stirring appropriately. A part of the water-insoluble organic compound may be present in addition to the polymer particles.
In the case where the colorant (C) is a hydrophobic dye or pigment, those in which the hydrophobic dye or pigment is contained in the polymer particles are preferable from the viewpoints 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 main dispersion by further 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 Co., 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 the colorant (C) 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 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 (C) 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 ink of the present invention includes the steps (1) to (3), and the water-insoluble organic compound (A) is present during or after at least one of the steps (1) to (3). ,Obtainable.
For example, in step (1), the water-insoluble organic compound (A), the water-insoluble polymer, the organic solvent, the colorant, water, and, if necessary, the 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. Otherwise, an aqueous dispersion of polymer particles containing the colorant (C) can be obtained under the same conditions as in the steps (1) to (3) described above.
Alternatively, in the step (1), the water-insoluble organic compound (A) 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), the water-insoluble organic compound (A) 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. Otherwise, an aqueous dispersion of polymer particles containing the colorant (C) can be obtained under the same conditions as in the steps (1) to (3) described above.
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 (C) 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 (C). 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 (C), 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, it is a production method of adding or mixing the water-insoluble organic compound (A) to the aqueous dispersion of polymer particles containing the colorant (C) 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 (C).

The aqueous dispersion of polymer particles may be used as an ink as it is, but wetting agents, penetrants, dispersants, viscosity modifiers, antifoaming agents, antifungal agents, rustproofing agents, etc., which are usually used in ink jet recording inks. It may be added.
The average particle diameter of the polymer particles (B) containing the water-insoluble organic compound (A) and / or the colorant (C) in the obtained ink is preferably from the viewpoint of prevention of clogging of the printer nozzle and dispersion stability. The thickness is 0.01 to 0.5 μm, more preferably 0.03 to 0.3 μm, and 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%.

(Ink set)
The ink set for ink-jet recording of the present invention comprises two or more different color (preferably chromatic) inks. Here, the “different color” means that the reflected light of the printed matter is measured at a wavelength of light of D65 / 2 using a spectral color difference meter SE-2000 manufactured by Nippon Denshoku Industries Co., Ltd., and L ^* a ^* b ^* when displayed in a color system, a ^* (red - green direction of chromaticity) and b ^* (yellow - blue direction of chromaticity) refers to a color not the same. Examples thereof include two or more chromatic colors selected from the group consisting of cyan, yellow, magenta, light cyan, dark yellow, and light magenta.
The ink set of the present invention is preferably a set comprising a combination of two or more inks selected from these chromatic colors. A three-color ink set, a four-color ink set, a five-color ink set, a six-color ink set, and a seven-color ink Any of more than a set may be sufficient.
More preferably, the ink set includes two or more different color inks selected from magenta ink, yellow ink, and cyan ink, which are the three subtractive primary colors, and the ink set including these three color inks is particularly preferable. preferable. The ink set includes magenta ink, yellow ink, and cyan ink, and two inks selected from the ink set are water-insoluble organic compound (A), polymer particles (B), and colorant (C). In another ink, the other one may not contain a water-insoluble organic compound. The ink set of the present invention may further include black ink such as self-dispersing carbon black.

(Method for producing printed matter)
The method for producing a printed matter according to the present invention is an ink set comprising two or more different color inks, and the ink of the ink set is printed on an inkjet photographic paper by an inkjet recording method. It is a method for producing (also called printed matter).
For example, if the ink set includes magenta ink and yellow ink, a secondary color of red can be printed. If yellow ink and cyan ink are provided, a secondary color of green can be printed. If a magenta ink and a cyan ink are provided, a blue secondary color can be printed. A tertiary color can be printed using three or more different colors, and similarly, a printed matter of a multi-order color such as a quaternary color is possible.
The multi-colored printed matter may be manufactured by overlapping dots of inks or may be manufactured by allowing dots of ink and ink to exist in parallel. In order to exert the effects of the present invention, it is preferable that at least a part of them is overlapped.
When the ink set of the present invention is a chromatic color ink set including magenta ink, yellow ink, and cyan ink, a black printed matter with composite black in which magenta ink, yellow ink, and cyan ink are overlapped is manufactured. Can do. In this case, it is preferable for black to obtain a photographic image that the 20 ° reflection glossiness of the inkjet photographic paper is 50 or more, preferably 70 or more.
The ink jet method to which the ink set 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.
Polymer synthesis examples 1 to 3
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) St macromer (Log P value = 165.72):
Styrene macromer, manufactured by Toagosei Co., Ltd., trade name: AS-6 (S), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group (c) BzMA: benzyl methacrylate (d) PP-800 (Log P value) = 2.67):
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 13, 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 (average added mole number of ethylene oxide = 8, average added mole number of propylene oxide = 6, terminal: 2-ethylhexyl group): manufactured by NOF Corporation, trade name: BLEMMER 50POEP-800B

Ink production example 1
30 parts of the polymer obtained by drying the polymer solution obtained in Synthesis Example 1 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and the neutralizing agent (5N aqueous sodium hydroxide solution) was neutralized in an amount and 60% neutralization. 230 parts of exchanged water was added to neutralize the salt-forming group, and dimethylquinacridone pigment (magenta: M) (CI Pigment Violet 19 [PV19], manufactured by Clariant Japan, trade name: Hostaperm Red E5B02) 70 parts were 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: The pigment-containing graft polymer particles having a solid content concentration of 20% are removed by filtering with a 25-mL needleless syringe (Terumo Corporation) 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 graft polymer particles and 1 part of dibutyl sebacate (LogP value = 6.30) were mixed and stirred to incorporate dibutyl sebacate in the polymer particles. 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.). The aqueous ink shown in Table 2 and Table 3 was obtained by removing the particles.

Ink production example 2
35 parts of a polymer obtained by drying the polymer solution obtained in Synthesis Example 2 under reduced pressure, and a diazo pigment (yellow: Y) (CI Pigment Yellow 74 [PY 74], manufactured by Sanyo Dye Co., Ltd.) as a pigment The product was manufactured in the same manner as in Production Example 1 except that 65 parts of the product name: FY7413) was used, and an aqueous dispersion of pigment-containing graft polymer particles having a solid content concentration of 20% was obtained.
A water-based ink shown in Table 2 was obtained in the same manner as in Production Example 1 except that 43.07 parts of the aqueous dispersion of the obtained pigment-containing graft polymer particles and 37.63 parts of ion-exchanged water were used.

Ink production example 3
40 parts of a polymer obtained by drying the polymer solution obtained in Synthesis Example 3 under reduced pressure, and a phthalocyanine pigment (cyan: C) (CI pigment blue 15: 4 [P.B. 15: 4], Toyo Ink Manufacturing Co., Ltd., trade name: LIONOGEN BLUE BGJ) was used in the same manner as in Production Example 1 to obtain an aqueous dispersion of pigment-containing graft polymer particles having a solid content concentration of 20%.
A water-based ink shown in Table 2 was obtained in the same manner as in Production Example 1 except that 33.33 parts of the obtained pigment-containing graft polymer particle aqueous dispersion and 47.37 parts of ion-exchanged water were used.

Ink production examples 4 to 12
The amount of dibutyl sebacate mixed with the aqueous dispersion of the pigment-containing graft polymer particles is set to the amount shown in Table 2, and the ion exchange water mixed with this mixed solution is adjusted to make the total amount of the water-based ink 100 parts. In the same manner as in Production Example 1 for magenta, Production Example 2 for yellow, and Production Example 3 for cyan, water-based inks shown in Tables 2 and 3 were obtained.
Ink production examples 13 to 15
Aqueous inks shown in Table 2 were obtained in the same manner as in Production Examples 1 to 3, except that dibutyl sebacate was changed to benzyl octyl phthalate (BzOP, LogP value = 6.79).

Examples 1-7 and Comparative Examples 1-2
Using the inks of Production Examples 1 to 15, composite black (RGB values are R: 0, G: 0, B: on a commercially available inkjet photographic paper (manufactured by Seiko Epson Corporation, trade name: KA450PSK) as shown below. 0), and secondary colors red (RGB values R: 255, G: 0, B: 0), green (RGB values R: 0, G: 128, B: 0), blue (RGB values R) : 0, G: 0, B: 255), surface tension and contact angle were measured by the following methods, and glossiness and image clarity were evaluated. The results are shown in Tables 2 and 3.
In the table, M represents magenta, Y represents yellow, and C represents cyan ink (the same applies hereinafter).

(Measurement of surface tension)
The surface tension of the ink was measured (25 ° C.) using a dynamic surface tension meter (trade name: CBVP-Z, manufactured by Kyowa Interface Chemical Co., Ltd.).
(Measurement of contact angle)
Using an automatic minimum contact angle meter (manufactured by Kyowa Interface Chemical Co., Ltd., trade name: MCA-1), discharging was performed using a capillary having an inner diameter of 30 μm from a point of 120 μm from a recording material at a drop amount of 1 nl. After 1 second, the contact angle of the ink droplet on the recording material (inkjet photographic paper <gloss> manufactured by Seiko Epson Corporation, trade name: KA450PSK 60 ° glossiness 41) was measured (25 ° C.).

(Glossiness evaluation)
Using a commercially available inkjet printer (Seiko Epson Corporation model number: PX-V600, piezo method) on a commercially available inkjet photo paper (trade name: inkjet photo paper <gloss>, Seiko Epson brand name: KA450PSK) Solid printing [printing condition = paper type: photographic paper <silk-tone>, mode setting: photo], left for 24 hours at 25 ° C, and glossiness of 20 ° (manufactured by Nippon Denka Kogyo Co., Ltd., product) Name: HANDY GLOSSMETER, product number: PG-1) was measured 5 times, and the average value was obtained.
〔Evaluation criteria〕
○: 50 or more △: 40 or more and less than 50 ×: less than 40

(Evaluation of image clarity)
Using the printer, solid printing was performed on the commercially available inkjet photographic paper, and after being allowed to stand at 25 ° C. for 24 hours, a 45 ° image clarity C value (comb width 2.0 mm) was measured using a image clarity measuring device (manufactured by Suga Test Instruments Co. , Trade name: touch panel type image clarity measuring instrument, product number: ICM-IT), and measured three times to obtain an average value.
〔Evaluation criteria〕
○: 35 or more △: 26 or more and less than 35 ×: Less than 26 The image clarity is a measure of the sharpness or distortion when the image is reflected on the printed matter. The larger the numerical value, the clearer the reflected image. With less distortion, the reflected image looks natural.

Example 8 and Comparative Example 3
Using the inks of Production Examples 1 and 2 (Example 8), or the inks of Production Examples 11 and 10 (Comparative Example 3), secondary to commercially available inkjet photographic paper (trade name: KA450PSK, manufactured by Seiko Epson Corporation) The color red (RGB values R: 255, G: 0, B: 0) was printed and evaluated in the same manner as in Example 1. The results are shown in Table 4.

  From the results of Tables 2 to 4, it can be seen that the ink set for ink jet recording obtained in the examples can obtain a secondary color or the like excellent in glossiness and image clarity and composite black. Further, the print density of each ink is sufficient for practical use.

Claims (11)

  An ink set comprising two or more different color inks, wherein the ink is an ink containing a water-insoluble organic compound (A), polymer particles (B) and a colorant (C). Ink set.   The ink set for inkjet recording according to claim 1, wherein the ink set is an ink set including magenta ink, yellow ink, and cyan ink.   An ink set comprising magenta ink, yellow ink and cyan ink, wherein two inks selected from the ink set contain a water-insoluble organic compound (A), polymer particles (B) and a colorant (C) An ink set for ink jet recording, wherein the other type is an ink that does not contain a water-insoluble organic compound.   The ink set for inkjet recording according to any one of claims 1 to 3, wherein a weight ratio of [water-insoluble organic compound (A) / polymer particle (B)] is from 1/100 to 5/1.   The ink set for inkjet recording according to any one of claims 1 to 4, wherein the content of the water-insoluble organic compound (A) in the ink is 0.11 to 10% by weight.   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 An 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 ink set for inkjet recording according to any one of the above.   The polymer particles (B) are water-insoluble polymer particles obtained by copolymerizing a monomer mixture containing (a) a salt-forming group-containing monomer and (b) a macromer and / or (c) a hydrophobic monomer. The ink set for inkjet recording in any one of -6.   The ink set for inkjet recording according to any one of claims 1 to 7, wherein the colorant (C) is contained in the polymer particles (B).   When ink was ejected onto ink jet photographic paper under the conditions of a drop nozzle inner diameter of 30 μm and a drop amount of 1 nl, the surface tension of the ink after 1 second (25 ° C.) was 20 to 35 mN / m. The ink set for inkjet recording according to any one of claims 1 to 8, wherein the contact angle is 15 to 60 °.   The ink set according to any one of claims 1 to 9, wherein the ink set comprises magenta ink, yellow ink, and cyan ink, and the ink of the ink set is printed on an inkjet photographic paper by an inkjet recording method. Manufacturing method of black printed matter with composite black.   The manufacturing method of the printed matter of multi-order color which prints the ink of 2 or more types of different colors provided in the ink set in any one of Claims 1-10 on an inkjet photographic paper with an inkjet recording method.