JP4451094B2 - Water-based ink for inkjet recording - Google Patents

Description

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

  The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording member and attaching them. According to this method, not only has the advantage that the device to be used is low noise and good operability, but also has the advantage that colorization is easy and plain paper can be used as a recording member. Widely used. Ink used in ink jet printers is mainly water-soluble dye-based ink, so it shows very clear color, and the dye is dissolved in water, so the ink has high transparency and hue. It is clear.

  However, the dye has a disadvantage that it is inferior in light resistance and a disadvantage that it is inferior in water resistance because the dye is water-soluble.

  In order to eliminate these drawbacks, pigments excellent in light resistance and water resistance have been used in recent years.

  Pigments have the advantage of being insoluble in water and excellent in light resistance, and copper phthalocyanine pigments are widely used for pigment-based cyan inks. However, copper phthalocyanine pigments do not have the greenish blue hue of direct blue 86, 199, etc., which are copper phthalocyanine dyes used in dye-based inks. It may be narrowed or reddish depending on the viewing angle.

  Therefore, an ink containing an aluminum phthalocyanine pigment and a water-soluble resin having a hue in the same color gamut as that of direct blue 86, 199, which is a copper phthalocyanine dye, is disclosed (see Patent Document 1). The print density and greenness are not sufficient.

JP 2000-17207 A

  The present invention relates to a water-based ink for ink-jet recording having a greenish blue color tone and capable of providing high print density when printed on plain paper and high gloss when printed on glossy paper, and the water system. It is an object of the present invention to provide an aqueous dispersion used for ink.

  The present invention relates to an aqueous dispersion for water-based ink in which polymer particles of a water-insoluble vinyl polymer containing an aluminum phthalocyanine pigment as a colorant are dispersed in water, and an aqueous ink for ink jet recording comprising the aqueous dispersion.

  The water-based ink for inkjet recording containing the aqueous dispersion of the present invention has a greenish blue color tone, imparts a high print density when printed on plain paper, and has a high gloss when printed on glossy paper. It has an excellent effect that it can be imparted with sex.

  The present invention is characterized in that in a water dispersion in which polymer particles of a water-insoluble vinyl polymer containing a colorant are dispersed in water, an aluminum phthalocyanine pigment, that is, a phthalocyanine pigment having aluminum as a central metal is used as the colorant. There is one feature. Since the aqueous dispersion of the present invention has an aluminum phthalocyanine pigment selected and used, it has a greenish blue color tone similar to a copper phthalocyanine dye, and the pigment is contained in the polymer particles. By using the aqueous dispersion of the present invention for water-based ink, the printing density when printing on plain paper and the glossiness when printing on glossy paper are improved.

  Examples of commercially available aluminum phthalocyanine pigments include Cyanine Blue A-13Y and Cyanine Blue A-13R (manufactured by Sanyo Dye Co., Ltd.).

  The content of the aluminum phthalocyanine pigment is preferably 1 to 25% by weight in the aqueous dispersion, preferably 0.5 to 15% by weight and more preferably 1 to 10% by weight in the aqueous ink.

  In the aqueous dispersion of the present invention, a water-insoluble vinyl polymer is used as the polymer from the viewpoint of enhancing the adsorptivity to the pigment.

  From the viewpoint of improving glossiness on glossy paper, it is preferable that the amount of polymer is large, but if the amount is too large, the viscosity of the water dispersion increases and exceeds the appropriate viscosity of the ink. Preferably it is 10-500 weight part with respect to 100 weight part of aluminum phthalocyanine pigments, More preferably, it is 20-200 weight part.

As a representative example of a water-insoluble vinyl polymer,
(A) Formula (I):

Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom, a phenyl group optionally having 1 to 20 carbon atoms or an alkyl group having 1 to 9 carbon atoms, R ³ is an oxy (At least one oxyalkylene group selected from the group consisting of an ethylene group, an oxypropylene group and an oxytetramethylene group, m represents a number of 1 to 30)
At least one monomer A (hereinafter simply referred to as “monomer A”) selected from the monomers represented by:
(B) a salt-forming group-containing monomer, and (C) a monomer copolymerizable with monomer A and a salt-forming group-containing monomer (hereinafter simply referred to as “copolymerizable monomer”)
And a water-insoluble vinyl polymer obtained by polymerizing a monomer mixture (hereinafter simply referred to as “monomer mixture”).

In the formula (I), R ¹ is a hydrogen atom or a methyl group. R ² is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group optionally having an alkyl group having 1 to 9 carbon atoms. Among these, an octyl group and a nonylphenyl group are preferable from the viewpoints of water resistance and scratch resistance. R ³ represents at least one oxyalkylene group selected from the group consisting of an oxyethylene group, an oxypropylene group and an oxytetramethylene group, and when two or more groups are added as the oxyalkylene group, 2 One or more oxyalkylene groups may be any of block addition, random addition, alternating addition, and the like.

  m is a number from 1 to 30. From the viewpoint of ejection properties and print density, m is preferably a number from 2 to 25.

  Since the water-insoluble vinyl polymer uses the nonionic and hydrophilic monomer A, the aqueous dispersion of the present invention can be used to obtain a water-based ink excellent in printed image density and gloss. it can. This is considered to be based on the fact that the hydrophilic hydrated layer of the oxyalkylene group having high hydrophilicity such as the oxyethylene group or oxypropylene group of the monomer A spreads in the water-based ink.

  Representative examples of monomer A include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, ethylene glycol / propylene glycol (meth) acrylate, poly (ethylene glycol / propylene glycol) mono (meth) acrylate, octoxy Polyethylene glycol / polypropylene glycol mono (meth) acrylate, octoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, stearoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, stearoxy poly (ethylene glycol / propylene glycol) mono ( (Meth) acrylate, nonylphenoxypolyethylene glycol / polypropylene glycol (Meth) acrylate, nonylphenoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, propylene glycol / tetramethylene glycol mono (meth) acrylate, poly (propylene glycol / tetramethylene glycol) mono (meth) acrylate, propylene Examples include glycol / polybutylene glycol mono (meth) acrylate, poly (propylene glycol / butylene glycol) mono (meth) acrylate, and the like. These can be used alone or in admixture of two or more.

  As used herein, “(meth) acryl” means “acryl” or “methacryl”.

  Specific examples of commercially available monomer A include NK ester M-20G, 40G, 90G, 230G manufactured by Shin-Nakamura Chemical Co., Ltd., Bremer PE series from Nippon Oil & Fats, PME-100, 200, 400, 1000, PP-1000, PP-500, PP-800, AP-150, AP-400, AP-550, AP-800, 50PEP-300, 70PEP-350B, AEP series, 30PPT-800, 50PPT-800 , 70PPT-800, APT series, 10PPB-500B, 10APB-500B, 50POEP-800B, 50AOEP-800B, ASEP series, PNEP series, PNPE series, 43ANEP-500, 70ANEP-550 and so on.

  The content of monomer A in the monomer mixture is preferably 5 to 45% by weight, more preferably 5 to 35% by weight, from the viewpoint of gloss of the printed matter and high print density.

  As the salt-forming group-containing monomer, an anionic monomer and a cationic monomer are preferable. Anionic monomers and cationic monomers can be used alone or in admixture of two or more.

  Examples of the anionic monomer include one or more selected from the group consisting of an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.

  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. These can be used alone or in admixture of two or more.

  Examples of unsaturated sulfonic acid monomers include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylic acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and the like. Can be mentioned. These can be used alone or in admixture of two or more.

  Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acrylic acid. And leuoxyethyl phosphate. These can be used alone or in admixture of two or more.

  Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of ink viscosity and dischargeability.

  Examples of the cationic monomer include one or more selected from the group consisting of an unsaturated tertiary amine-containing vinyl monomer and an unsaturated ammonium salt-containing vinyl monomer.

  Examples of unsaturated tertiary amine-containing vinyl monomers include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethylarylamine, vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-6-vinylpyridine, 5-ethyl-2-vinylpyridine, etc. Can be mentioned. These can be used alone or in admixture of two or more.

  Examples of the unsaturated ammonium salt-containing vinyl monomer include N, N-dimethylaminoethyl (meth) acrylate quaternized product, N, N-diethylaminoethyl (meth) acrylate quaternized product, N, N-dimethylaminopropyl (meth) ) Acrylate quaternized product and the like. These can be used alone or in admixture of two or more.

  Among the cationic monomers, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide and vinyl pyrrolidone are preferable.

  The content of the salt-forming group-containing monomer in the monomer mixture is 3 to 40% by weight, preferably 5 to 30% by weight, from the viewpoints of dispersion stability and ejection stability.

  Examples of the copolymerizable monomer include (meth) acrylic acid esters, aromatic ring-containing monomers, macromers, and the like. These can be used alone or in admixture of two or more. The copolymerizable monomer preferably contains at least one selected from the group consisting of an aromatic ring-containing monomer and a macromer from the viewpoint of water resistance and scratch resistance.

  Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meta) ) Acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (iso) stearyl (meth) ) (Meth) acrylic acid esters in which the ester moiety such as acrylate is an alkyl group having 1 to 18 carbon atoms, and these may be used alone or in admixture of two or more.

  In addition, said (iso or tertiary) and (iso) mean both the case where these groups exist, and the case where it is not so, and when these groups do not exist, it shows normal.

  From the viewpoint of water resistance, the aromatic ring-containing monomer is selected from styrene, vinyl naphthalene, α-methyl styrene, vinyl toluene, ethyl vinyl benzene, 4-vinyl biphenyl, 1,1-diphenyl ethylene, benzyl (meth) acrylate, phenoxyethyl ( Selected from the group consisting of (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate and neopentyl glycol acrylate benzoate 1 or more types are preferable. Among these, at least one selected from the group consisting of styrene, α-methylstyrene, vinyl toluene, and vinyl naphthalene is more preferable from the viewpoint of water resistance and scratch resistance.

  A typical example of the macromer is a macromer having a polymerizable functional group at one end and preferably having a number average molecular weight of 500 to 500,000, more preferably 1,000 to 10,000.

  Specific examples of the macromer include a styrene macromer having a polymerizable functional group at one end, a silicone macromer having a polymerizable functional group at one end, a methyl methacrylate macromer having a polymerizable functional group at one end, Examples thereof include a styrene / acrylonitrile macromer having a polymerizable functional group, a butyl acrylate macromer having a polymerizable functional group at one end, and an isobutyl methacrylate macromer having a polymerizable functional group at one end. Among these, a styrenic macromer having a polymerizable functional group at one end is preferable from the viewpoint of sufficiently containing a colorant in the water-insoluble vinyl polymer.

  Examples of the styrenic macromer having a polymerizable functional group at one end include a styrene homopolymer having a polymerizable functional group at one end and a copolymer of styrene and another monomer having a polymerizable functional group at one end. Can be mentioned.

  In the copolymer of styrene and another monomer having a polymerizable functional group at one end, examples of the other monomer include acrylonitrile. Further, the content of styrene is preferably 60% by weight or more, more preferably 70% by weight or more from the viewpoint that the pigment is sufficiently contained in the water-insoluble vinyl polymer.

  Among the styrenic macromers having a polymerizable functional group at one end, a styrenic macromer having an acryloyloxy group or a methacryloyloxy group as a polymerizable functional group at one end is preferable.

  Examples of commercially available styrenic macromers include AS-6, AS-6S, AN-6, AN-6S, HS-6S, and HS-6 manufactured by Toa Gosei Co., Ltd.

Among the silicone macromers, the formula (II):
X (Y) _q Si (R ⁴ ) _3-r (Z) _r (II)
(Wherein X is a polymerizable unsaturated group, Y is a divalent linking group, R ⁴ is independently a hydrogen atom, a lower alkyl group, an aryl group or an alkoxy group, and Z is a number average molecular weight of 500 or more. A monovalent siloxane polymer residue, q is 0 or 1, and r is an integer of 1 to 3)
Is preferable from the viewpoint of preventing scorching of the head of the inkjet printer.

In the silicone macromer represented by the formula (II), X is a polymerizable unsaturated group. Representative examples of polymerizable unsaturated groups, CH ₂ = CH- _{group, CH 2 = C (CH 3} ) - include monovalent unsaturated hydrocarbon group having 2 to 6 carbon atoms such as groups.

Y is a divalent linking group. Representative examples of the divalent linking group include a divalent linking group such as a -COO- group, a -COO C _a H _2a -group (a represents an integer of 1 to 5), and a phenylene group. Of these, -COOC ₃ H ₆ -is preferable.

R ⁴ is each independently a hydrogen atom, a lower alkyl group, an aryl group or an alkoxy group. Specific examples of R ⁴ include a hydrogen atom; a lower alkyl group having 1 to 5 carbon atoms such as a methyl group and an ethyl group; an aryl group having 6 to 20 carbon atoms such as a phenyl group; and a C 1 to 20 carbon atom such as a methoxy group. And the like. In these, a methyl group is preferable.

  Z is preferably a residue of a monovalent siloxane polymer having a number average molecular weight of 500 or more. Preferable Z includes a monovalent residue of a dimethylsiloxane polymer having a number average molecular weight of 500 to 5,000.

  q is 0 or 1, but preferably 1. r is an integer of 1 to 3, and more preferably 1.

Representative examples of silicone macromers include the formula (III):
CH ₂ = CR ⁵ -COOC ₃ H _6- [Si (R ⁶ ) ₂ -O] _b -Si (R ⁶ ) ₃ (III)
(Wherein R ⁵ is a hydrogen atom or a methyl group, R ⁶ is independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and b is a number of 5 to 60), Formula (IV):
CH ₂ = CR ⁵ -COO- [Si (R ⁶ ) ₂ -O] _b -Si (R ⁶ ) ₃ (IV)
(Wherein R ⁵ , R ⁶ and b are as defined above), a silicone macromer represented by formula (V):
CH ₂ = CR ⁵ -Ph- [Si (R ⁶ ) ₂ -O] _b -Si (R ⁶ ) ₃ (V)
(Wherein Ph is a phenylene group, R ⁵ , R ⁶ and b are as defined above), a silicone macromer represented by the formula (VI):
CH ₂ = CR ⁵ -COOC ₃ H ₆ -Si (OE) ₃ (VI)
[Wherein R ⁵ is the same as defined above. E represents the formula:-[Si (R ⁵ ) ₂ -O] _c -Si (R ⁵ ) ₃ group (R ⁵ is the same as above; c represents a number of 5 to 65)
The silicone macromer etc. which are represented by these are mentioned.

Among these, the silicone macromer represented by the formula (III) is preferable, and particularly the formula (VII):
CH ₂ = C (CH ₃ ) -COOC ₃ H _6- [Si (CH ₃ ) ₂ -O] _d -Si (CH ₃ ) ₃ (VII)
(In the formula, d represents a number of 8 to 40)
The silicone macromer represented by these is preferable. Examples thereof include FM-0711 [manufactured by Chisso Corporation].

  The number average molecular weight of the macromer is measured using polystyrene as a standard substance by gel permeation chromatography using 1 mmol / L chloroform containing dodecyldimethylamine as a solvent.

  The content of the copolymerizable monomer in the monomer mixture is preferably 15 to 87% by weight, more preferably 35 to 85% by weight, from the viewpoint of printing density and water resistance.

  Further, the content of the aromatic ring-containing monomer in the monomer mixture is preferably 0.1 to 70% by weight, more preferably 1 to 50% by weight, from the viewpoints of water resistance, scratch resistance, ink viscosity and ejection stability.

  The content of the macromer in the monomer mixture is preferably 0.1 to 40% by weight, more preferably 1 to 30% by weight, from the viewpoint of water resistance and scratch resistance.

  The weight average molecular weight of the water-insoluble vinyl polymer (measured by the method described in Production Examples 1 to 3 described later) is preferably 3000 to 300,000, more preferably 5000 to 200,000, from the viewpoints of print density and ejection stability.

  The water-insoluble vinyl polymer is produced by polymerizing 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 preferably a polar organic solvent. 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 solution of these with water is preferable.

  In the polymerization, a radical polymerization initiator can be used. As radical polymerization initiators, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobisbutyrate, 2, 2 An azo compound such as' -azobis (2-methylbutyronitrile), 1,1'-azobis (1-cyclohexanecarbonitrile) is preferred. Moreover, organic peroxides, such as t-butyl peroxy octoate, di-t-butyl peroxide, dibenzoyl oxide, can also be used.

  The amount of the 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 polymerization chain transfer agent may be further added. Specific examples of the polymerization chain transfer agent include mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-tetradecyl mercaptan and 2-mercaptoethanol; xanthogen disulfides such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide. ; Thiuram disulfides such as tetramethylthiuram disulfide and tetrabutylthiuram disulfide; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; hydrocarbons such as pentaphenylethane; acrolein, methacrolein, allyl alcohol, 2- Ethylhexyl thioglycolate, terbinolene, α-terpinene, γ-terpinene, dipentene, α-methylstyrene dimer, 9, 10-dihydroanthracene, 1, - dihydronaphthalene, indene, 1, 4-cyclohexadiene unsaturated cyclic hydrocarbon compounds of a diene and the like; 2, unsaturated heterocyclic compounds such as 5-dihydrofuran, and the like. These polymerization chain transfer agents can be used alone or in admixture of two or more.

  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 an inert gas atmosphere such as nitrogen gas.

  After completion of the polymerization reaction, the produced water-insoluble vinyl polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. The obtained water-insoluble vinyl polymer can be purified by repeating reprecipitation or removing unreacted monomers by membrane separation, chromatographic methods, extraction methods, and the like.

  As a method of obtaining an aqueous dispersion in which polymer particles containing an aluminum phthalocyanine pigment are dispersed in water, the polymer is dissolved in an organic solvent, and an aluminum phthalocyanine pigment, water, a neutralizing agent and, if necessary, a surfactant are added. After kneading, it is preferable to dilute with water if necessary and distill off the organic solvent to make an aqueous system.

  As the organic solvent, hydrophilic organic solvents such as alcohol solvents, ketone solvents and ether solvents are preferable.

  Examples of the alcohol solvent include methanol, ethanol, isopropanol, n-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Of these solvents, isopropanol, acetone and methyl ethyl ketone are preferred.

  If necessary, an organic solvent and a high-boiling hydrophilic organic solvent may be used in combination. Examples of the high-boiling hydrophilic organic solvent include phenoxyethanol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, and the like.

  As the neutralizing agent, an acid or a base can be used depending on the type of the salt-forming group. Examples of the acid include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid, propionic acid, lactic acid, succinic acid, glycolic acid, gluconic acid, and glyceric acid. Examples of the base include tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide and the like.

  There is no particular limitation on the degree of neutralization. Usually, it is preferable that pH of the obtained water dispersion is 4.5-10. The solubility of the water-insoluble vinyl polymer after neutralization in water at 25 ° C. is preferably 10% by weight or less, more preferably 5% by weight or less, and still more preferably 1% by weight or less from the viewpoint of reducing the viscosity of the water-based ink.

  The average particle size of the polymer particles containing the aluminum phthalocyanine pigment is preferably 0.01 to 0.50 μm, more preferably 0.02 to 0.30 μm, and even more preferably 0.05 to 0.20 μm, from the viewpoint of nozzle clogging prevention and dispersion stability. is there.

  Thus, the aqueous dispersion of the present invention can be obtained. The water content in the aqueous dispersion of the present invention is preferably 40 to 90% by weight.

  The aqueous ink for inkjet recording of the present invention contains the aqueous dispersion. The amount of the polymer particle aqueous dispersion containing the aluminum phthalocyanine pigment in the water-based ink is usually from the viewpoint of printing density and ejection stability, and the content (solid content) of the polymer particles in the water-based ink is preferably 0.5 to 30. It is desirable to adjust so that it may become weight%, More preferably, it is 1 to 15 weight%.

  In the water-based ink of the present invention, water other than the polymer particles is water. If necessary, additives such as a wetting agent, a dispersing agent, an antifoaming agent, an antifungal agent, and a chelating agent can be contained.

  Wetting agents include C2-C8 alkyl diols such as ethylene glycol and propylene glycol, polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, diethylene glycol diethyl ether, diethylene glycerin mono n-butyl ether and the like. Nitrogen-containing compounds such as ethers, acetates, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone can be used. The amount of the wetting agent in the water-based ink is preferably 0.1 to 50% by weight, more preferably 0.1 to 30% by weight. The amount of water in the water-based ink is preferably 40 to 90% by weight.

  As the dispersant, an anionic, nonionic, cationic or amphoteric dispersant can be used.

  Moreover, since the aluminum phthalocyanine pigment which is a pigment is used as the colorant of the water-based ink of the present invention, a printed matter having excellent light resistance and water resistance can be obtained.

  Furthermore, when at least one of an aromatic ring-containing monomer and a macromer is used as the water-insoluble vinyl polymer, a printed matter excellent in water resistance and scratch resistance can be obtained.

  In addition, since the water-based ink of the present invention suppresses permeation into paper having a hydrophilic surface due to the imparted high hydrophobicity, the colorant can be effectively left on the paper surface, so that high printing can be achieved. The concentration can be obtained.

Production Examples 1-3
In a reaction vessel, 20 parts by weight of methyl ethyl ketone, 0.03 part by weight of a polymerization chain transfer agent (2-mercaptoethanol), and 10% by weight of each monomer amount (parts by weight) shown in Table 1 are mixed. Then, nitrogen gas replacement was sufficiently performed to obtain a mixed solution.

  On the other hand, the remaining 90% by weight of the amount (parts by weight) of each monomer shown in Table 1 was charged into the dropping funnel, then 0.27 parts by weight of a polymerization chain transfer agent (2-mercaptoethanol), and 60 parts by weight of methyl ethyl ketone. Then, 1.2 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was added and mixed, followed by sufficient nitrogen gas substitution 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 into the reaction vessel over 3 hours. After completion of the dropwise addition, the temperature of the mixed solution is maintained at 65 ° C. for 2 hours, and then mixed with a solution obtained by dissolving 0.3 part by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) in 5 parts by weight of methyl ethyl ketone. In addition to the solution, it was further aged at 65 ° C. for 2 hours and 70 ° C. for 2 hours to obtain a polymer solution.

  A portion of the polymer solution obtained was isolated by drying at 105 ° C. under reduced pressure for 2 hours and removing the solvent, polystyrene as the standard, 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as the solvent. The weight average molecular weight of the obtained polymer was measured by gel permeation chromatography using dimethylformamide containing. The results are shown in Table 1.

The details of each compound shown in Table 1 are as follows.
-Polyethylene glycol monomethacrylate: manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK ester M-90G, in formula (I), R ¹ and R ² are each a methyl group, R ³ is an oxyethylene group, and m is 9 is there.
Polypropylene glycol monomethacrylate: manufactured by Nippon Oil & Fats Co., Ltd., trade name: BLEMMER PP-500, in formula (I), R ¹ is a methyl group, R ² is a hydrogen atom, R ³ is an oxypropylene group, m is 5 is there.

-Styrenic macromer: manufactured by Toa Gosei Co., Ltd., trade name: AS-6S (styrene homopolymerized macromer), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group

Examples 1-3
6 parts by weight of the polymer obtained by drying the polymer solutions obtained in Production Examples 1 to 3 under reduced pressure was dissolved in 45 parts by weight of methyl ethyl ketone, and 1.41 parts by weight of a neutralizing agent (20% aqueous sodium hydroxide solution) was dissolved therein. In addition, after neutralizing the salt-forming group, 18 parts by weight of an aluminum phthalocyanine pigment (manufactured by Sanyo Color Co., Ltd., trade name: Cyanine Blue A-13Y) was added as a phthalocyanine pigment, and the mixture was kneaded for 30 minutes with a three-roll mill.

  To the obtained kneaded product, 120 parts by weight of ion-exchanged water was added and stirred, and then methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was further removed, so that the solid content concentration was 20% by weight. An aqueous dispersion of water-insoluble vinyl polymer particles containing a colorant was obtained.

  40 parts by weight of an aqueous dispersion of the obtained colorant-containing water-insoluble vinyl polymer particles, 10 parts by weight of glycerin, 5 parts by weight of 2-pyrrolidone, 2 parts by weight of isopropanol and 43 parts by weight of ion-exchanged water were mixed, and the resulting mixture was obtained. The liquid was filtered with a 25 mL needleless syringe (Terumo Corporation) equipped with a 0.5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) to remove coarse particles. A water-based ink having the composition shown in Table 2 was obtained.

Comparative Example 1
In Example 2, instead of an aluminum phthalocyanine pigment (Sanyo Dye Co., Ltd., trade name: Cyanine Blue A-13Y), a copper phthalocyanine pigment [CI Pigment Blue 15: 3, Toyo Ink Co., Ltd. ), Trade name: LIONOL BLUE 7350] was used in the same manner as in Example 2 to obtain a water-based ink having the composition shown in Table 2.

Comparative Example 2
In 96 parts by weight of ion-exchanged water, 18 parts by weight of an aluminum phthalocyanine pigment (manufactured by Sanyo Dye Co., Ltd., trade name: Cyanine Blue A-13Y) and an acrylic resin (manufactured by Johnson Polymer Co., Ltd., trade name: Jonkrill 62) 6 parts by weight were added and kneaded in a bead mill for 2 hours to obtain an aqueous dispersion of pigment particles having a solid content concentration of 20% by weight.

  An aqueous dispersion of pigment particles obtained in place of the aqueous dispersion of water-insoluble vinyl polymer particles containing the colorant was treated in the same manner as in Example 1 to obtain an aqueous ink having the composition shown in Table 2.

  Next, the physical properties of the obtained water-based ink were evaluated based on the following methods. The results are shown in Table 2.

(1) Print density Using a commercially available ink jet printer (manufactured by Epson Corporation, model number: EM-900C), solid printing is performed on commercially available plain paper (high quality plain paper, Epson Corporation, trade name: KA4250NP) [ Print condition = paper type: plain paper, mode setting: fast), left at 25 ° C for 1 hour, measure print density with Macbeth densitometer (Macbeth, product number: RD914), and evaluate based on the following evaluation criteria did.

〔Evaluation criteria〕
◎: Print density is 1.1 or more ○: Print density is 1.0 or more and less than 1.1 △: Print density is 0.9 or more and less than 1.0 ×: Print density is less than 0.9

(2) Glossy Using the printer, solid printing was performed on commercially available dedicated paper [MC glossy paper, manufactured by Epson Corporation, product name: KA420MK] [printing condition = paper type: dedicated glossy film, mode setting: photo], After being allowed to stand at 25 ° C. for 1 hour, the gloss at 60 ° was measured with a gloss meter (manufactured by Nippon Denshoku Co., Ltd., trade name: HANDY GLOSSMETER, product number: PG-1) and evaluated based on the following criteria.

〔Evaluation criteria〕
◎: Gloss is 40 or more ○: Gloss is 35 or more and less than 40 △: Gloss is 30 or more and less than 35 ×: Gloss is less than 30

(3) Color reproduction range The solid printed matter whose print density was measured was printed using the NIPPON DENSHOKU Spectro Color Meter SE2000 (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.), and the printed matter at a wavelength of D65 / 2 light. The reflected light was measured and the color reproduction range was measured and evaluated based on the following criteria. The larger the negative value of a ^*, the stronger the green color.

〔Evaluation criteria〕
◎: a ^* value is less than −20 ○: a ^* value is −20 or more and less than −10 Δ: a ^* value is −10 or more and less than 0 ×: a ^* value is 0 or more

  From the results shown in Table 2, it can be seen that each of the water-based inks obtained in each Example exhibits a greenish color tone. Furthermore, it can be seen that the water-based inks obtained in the respective examples give high density printing on plain paper and high gloss printing on glossy paper.

  The aqueous dispersion of the present invention can be suitably used for an aqueous ink for inkjet recording.

Claims (6)

An aqueous dispersion for water-based ink in which polymer particles of a water-insoluble vinyl polymer containing only an aluminum phthalocyanine pigment as a colorant are dispersed in water, wherein the water-insoluble vinyl polymer is
(A) Formula (I):

Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom, a phenyl group optionally having 1 to 20 carbon atoms or an alkyl group having 1 to 9 carbon atoms, R ³ is an oxy (At least one oxyalkylene group selected from the group consisting of an ethylene group, an oxypropylene group and an oxytetramethylene group, m represents a number of 1 to 30)
At least one monomer A selected from the monomers represented by:
(B) a salt-forming group-containing monomer, and
(C) Monomer copolymerizable with monomer A and a salt-forming group-containing monomer
An aqueous dispersion for water-based inks, which is a water-insoluble vinyl polymer obtained by polymerizing a monomer mixture containing. The content of monomer A in the monomer mixture is 5 to 45% by weight, the content of the salt-forming group-containing monomer is 3 to 40% by weight, and the content of the copolymerizable monomer is 15 to 87% by weight. Water dispersion.   The aqueous dispersion according to claim 1 or 2, wherein the copolymerizable monomer contains one or more selected from the group consisting of an aromatic ring-containing monomer and a macromer.   The aqueous dispersion according to claim 3, wherein the aromatic ring-containing monomer is at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, and vinylnaphthalene.   The aqueous dispersion according to claim 3, wherein the macromer is a styrenic macromer having a polymerizable functional group at one end.   An aqueous ink for ink-jet recording comprising the aqueous dispersion according to any one of claims 1 to 5.