JP2006348242A - Ink composition, and method for recording therewith, and recorded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition for ink jet recording, which gives excellent printing qualities to various recording media and especially has excellent ink reliability and excellent fixity to glossy paper. <P>SOLUTION: This ink composition comprises at least a quinacridone-based magenta pigment, a water-insoluble vinyl polymer A containing the pigment and capable of dispersing the pigment in the ink composition, a water-insoluble vinyl polymer B not containing the pigment, and water. The water-insoluble vinyl polymer A is preferably a vinyl polymer obtained by polymerizing a monomer composition comprising a polyoxyalkylene group-containing monomer, a salt-producing group-containing monomer, a macromer having a number-average mol. wt. of 500 to 500,000, and one or more monomers capable of being copolymerized with them, and the water-insoluble vinyl polymer B is preferably a vinyl polymer obtained by polymerizing a monomer composition comprising styrene monomer and one or more monomers capable of being copolymerized with the styrene monomer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

Background of the Invention

FIELD OF THE INVENTION The present invention relates to an ink composition for ink jet recording having excellent print quality on various recording media, in particular, excellent ink reliability and excellent fixability to glossy paper, and an ink composition thereof. The present invention relates to a recording method used and recorded matter.

BACKGROUND ART An ink jet recording method is a method of recording characters and figures on the surface of a recording medium such as paper by ejecting ink droplets from a fine nozzle head. As an ink jet recording method, an electric signal is converted into a mechanical signal using an electrostrictive element, and ink droplets stored in the nozzle head portion are intermittently ejected to record characters and symbols on the surface of the recording medium. A part of the ink liquid is rapidly heated near the discharge part of the head to generate bubbles, and ink droplets are intermittently discharged by the volume expansion caused by the bubbles, and characters and symbols are printed on the surface of the recording medium. A recording method has been put to practical use.

  As the ink for inkjet recording, an aqueous ink in which a colorant composed of a dye or a pigment is dispersed in water may be used. In such water-based inks, it is common to use a dispersant such as a surfactant or a polymer dispersant, or to disperse the colorant in the aqueous dispersion medium by hydrophilizing the particle surface of the organic pigment. Many proposals have been made regarding the ink composition. For example, in Japanese Patent Application Laid-Open No. 2004-2662 (Patent Document 1), Japanese Patent Application Laid-Open No. 2004-75988 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2005-42012 (Patent Document 3), A pigment ink containing a pigment and having high color development and excellent gloss has been proposed. Japanese Patent Application Laid-Open No. 10-110110 (Patent Document 4) discloses an organic pigment in order to provide an excellent pigment that is excellent in initial dispersibility and long-term dispersibility in water and an organic solvent and is less likely to cause aggregation of pigment particles. A method for producing a surface-treated pigment in which sulfonic acid groups are introduced on the surface of pigment particles is disclosed.

  However, when printed on a recording medium such as glossy paper, when the recorded material is put in and out of a container such as a clear file, the surface of the recorded material changes due to rubbing with the clear file, or when the recorded materials overlap, There is a problem that the surface state of the recorded matter changes due to rubbing, and improvement of the abrasion resistance has been demanded.

On the other hand, Japanese Patent Laid-Open No. 2001-329199 (Patent Document 5) discloses high printing on plain paper by adding different kinds of polymer particles in addition to polymer particles obtained by adding a pigment to a water-insoluble polymer. A water-based ink composition having a high density and excellent abrasion resistance has been proposed, but further improvement has been demanded for the fixability of special paper such as glossy paper and ink reliability. .
JP 20042662 A JP 2004-75988 A JP 2001-329199 A JP-A-10-110110 JP 2001-329199 A

Summary of the Invention

  In the ink composition for ink jet recording using a quinacridone-based magenta pigment as a colorant, the present inventors have recently added a styrene-based water-insoluble polymer in addition to a specific water-insoluble polymer including the pigment. The present inventors have found that an ink composition for ink jet recording having excellent ink reliability and excellent fixability to glossy paper can be realized. The present invention is based on this finding.

  Accordingly, an object of the present invention is to provide an ink composition for ink jet recording which has excellent print quality on various recording media, in particular, excellent ink reliability and excellent fixability to glossy paper. is there.

  The ink composition according to the present invention includes a quinacridone magenta pigment, a water-insoluble vinyl polymer A containing the pigment and capable of dispersing the pigment in the ink composition, and a water-insoluble vinyl polymer not containing the pigment. It comprises at least B and water.

  According to the present invention, in an ink composition using a quinacridone-based magenta pigment as a colorant, the water-insoluble vinyl polymer containing the pigment and capable of dispersing the pigment in the ink composition and the pigment are not contained. By combining with a water-insoluble vinyl polymer, an ink composition for ink jet recording having excellent ink reliability and excellent fixability to glossy paper can be realized.

Detailed description of the invention

  The ink composition according to the present invention comprises a quinacridone magenta pigment, a water-insoluble vinyl polymer A containing the pigment and capable of dispersing the pigment in the ink composition, and a water-insoluble vinyl polymer B not containing the pigment. And at least water. Hereinafter, each component constituting the ink composition according to the present invention will be described.

Water-insoluble vinyl polymer A
The polymer used in the ink composition according to the present invention is a vinyl monomer obtained by polymerizing the monomers and macromers of the following 1) to 4).

(1) Polyoxyalkylene group-containing monomer The polyoxyalkylene group-containing monomer is represented by a monomer A1 represented by the following formula (I), a monomer A2 represented by the following formula (II), and a formula (III). Means at least one monomer selected from monomers A3.

（式中、Ｒ^１は水素原子またはメチル基を表し、Ｒ^２は水素原子、炭素数１〜２０のアルキル基または、炭素数１〜９のアルキルフェニル基を表し、ｏは１〜３０の数を表す。）
式（II）：

（式中、Ｒ^１、Ｒ^２およびｏは式（I）で定義したものと同じ意味を表し、ｐは１〜３０の数を表し、[ ]内のオキシエチレン基およびオキシプロピレン基はブロック付加またはランダム付加のいずれであってもよい。）
式（III）：

（式中、Ｒ^１、Ｒ^２およびｏは、式（I）で定義したものと同じ意味を表す。）
モノマーＡ１の具体例としては、ポリプロピレングリコールモノ（メタ）アクリレート等が挙げられる。 Formula (I):

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkylphenyl group having 1 to 9 carbon atoms, and o is a number from 1 to 30. Represents.)
Formula (II):

(In the formula, R ¹ , R ² and o represent the same meaning as defined in formula (I), p represents a number of 1 to 30, and the oxyethylene group and oxypropylene group in [] are block additions. Or any of random addition may be used.)
Formula (III):

(In the formula, R ¹ , R ² and o have the same meaning as defined in formula (I).)
Specific examples of the monomer A1 include polypropylene glycol mono (meth) acrylate.

  Specific examples of the monomer A2 include 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 / ethylene glycol). Propylene glycol) mono (meth) acrylate, stearoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, stearoxy poly (ethylene glycol / propylene glycol) mono (meth) acrylate, nonylphenoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate , Nonylphenoxypoly (ethylene glycol / propylene glycol) mono ( Data) acrylate, and the like. These can be used alone or in admixture of two or more.

  Examples of commercially available monomers A1 or A2 include Blemmer PP-1000, PP-500, PP-800, AP-150, AP-400, AP-550, AP-800, 50PEP manufactured by NOF Corporation. -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 etc. are mentioned.

  Specific examples of the monomer A3 include polyethylene glycol mono (meth) acrylate.

  Specific examples of the commercially available monomer A3 include NK ester M-20G, 40G, 90G, 230G manufactured by Shin-Nakamura Chemical Co., Ltd., Bremer PE series manufactured by NOF Corporation, PME-100, 200, 400, 1000. Etc.

  The content of the monomer A) in the vinyl polymer is preferably 5 to 45% by weight, more preferably 5 to 35% by weight, from the viewpoint of printing density and ink viscosity.

(2) Salt-forming group-containing monomer As this salt-forming group-containing monomer, an anionic monomer or a cationic monomer is preferably used. Anionic monomers and cationic monomers can be used alone or in admixture of two or more.

  Specific 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.

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

  As the anionic monomer, an unsaturated carboxylic acid monomer is preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoint of ink viscosity and dischargeability.

  Examples of the cationic monomer include polyvinylamine, polyallylamine, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropylacrylamide and the like. Of these, N, N-dimethylaminoethyl acrylate and N, N-dimethylaminopropylacrylamide are particularly preferable.

  The content of monomer B) in the vinyl polymer is 3 to 40% by weight, preferably 5 to 30% by weight, from the viewpoints of dispersion stability and ejection stability.

(3) Macromer A macromer is a styrenic macromonomer having a number average molecular weight of 500 to 500,000.

  Preferred examples of the macromer C) include macromers 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 C) include a styrene macromer having a polymerizable functional group at one end, and a styrene / acrylonitrile macromer having a polymerizable functional group at one end. Among these, since a vinyl polymer can be sufficiently contained with a colorant, a styrenic macromer having a polymerizable functional group at one end is preferable.

  Acrylonitrile is mentioned as a monomer other than styrene constituting the styrenic macromonomer having a polymerizable functional group at one end. 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 vinyl polymer.

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

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

  The content of the macromer in the water-insoluble vinyl polymer A is preferably 0.1 to 40% by weight, more preferably 1 to 30% by weight from the viewpoint of water resistance and scratch resistance.

(4) Monomer Monomer 4) is copolymerizable with the above polyoxyalkylene group-containing monomer, salt-forming group-containing monomer, and macromer, and specific examples thereof include, for example, (meth) acrylic acid ester, aromatic ring-containing A monomer and a macromer are mentioned. These can be used alone or in admixture of two or more. This monomer D) preferably contains at least one selected from the group consisting of aromatic ring-containing monomers and macromers 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, benzyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (Meth) acrylic acid esters in which the ester moiety such as (iso) stearyl (meth) acrylate is an alkyl group having 1 to 18 carbon atoms are used, and these may be used alone or in combination of two or more. Can do.

  The terms “(iso or tertiary)” and “(iso)” mean both the case where these groups are present and the case where these groups are not present. Indicates.

  From the viewpoint of water resistance, the aromatic ring-containing monomer includes styrene, vinyl naphthalene, α-methylstyrene, vinyl toluene, ethyl vinyl benzene, 4-vinyl biphenyl, 1,1-diphenyl ethylene, benzyl (meth) acrylate, phenoxyethyl ( 1 selected from the group consisting of (meth) acrylate, 2-hydroxy-3phenoxypropyl acrylate, 2-methacryloyloxyethyl-2hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate and neopentyl glycol acrylate benzoate More than species are preferred. 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.

  These monomers in the water-insoluble vinyl monomer A obtained by polymerizing the above polyoxyalkylene group-containing monomer 1), salt-forming group-containing monomer 2), macromer 3) having a number average molecular weight of 500 to 500,000, and monomer 4) The polyoxyalkylene group-containing monomer 1) is 5 to 45% by weight (preferably 5-35% by weight), and the salt-forming group-containing monomer 2) is 3 to 40% by weight (preferably 5 to 30% by weight). ), Macromer 3) is 0.1 to 40% by weight (preferably 10 to 30% by weight), and monomer 4) is 0 to 87% by weight (preferably 0 to 75% by weight).

  The weight average molecular weight of the water-insoluble vinyl polymer A is preferably 3,000 to 300,000, more preferably 5,000 to 200,000, from the viewpoints of print density and ejection stability.

Synthesis of Water-Insoluble Vinyl Polymer A A water-insoluble vinyl polymer A can be synthesized by polymerizing a composition containing the above-described monomer by the following method.

  The water-insoluble vinyl polymer A is produced by polymerizing the monomer composition A 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 of the monomer composition, a radical polymerization initiator can be used. Examples of the radical polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobisbutyrate, 2, Azo compounds such as 2′-azobis (2-methylbutyronitrile), 1,1′-azobis (1-cyclohexanecarbonitrile); t-butyl peroxyoctate, di-t-butyl peroxide, dibenzoyl oxide, etc. Organic peroxides can be used.

  The amount of the polymerization initiator added per mole of the monomer composition is preferably 0.001 to 5 moles, and more preferably 0.01 to 2 moles.

  In the polymerization of the monomer composition, a polymerization chain transfer agent may be added in addition to the radical polymerization initiator. 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 methylthiuram disulfide and tetrabutylthiuram disulfide; Halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; Hydrocarbons such as pentaphenylethane; Acrolein, methacrolein, allyl alcohol, 21-ethylhexylthio Glycolate, 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; 2,5-unsaturated heterocyclic compounds dihydrofuran like can be used. These polymerization chain transfer agents can be used alone or in admixture of two or more.

  The polymerization conditions of the composition containing the monomer described above vary depending on the type of radical polymerization initiator, monomer, and solvent used. 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 vinyl polymer is isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained vinyl polymer can be purified by repeating reprecipitation or removing unreacted monomers by membrane separation, chromatographic method, extraction method or the like.

Preparation of particle dispersion of water-insoluble polymer A containing pigment A pigment dispersion using the water-insoluble vinyl polymer A as a dispersant can be prepared, for example, by the method described in JP-A-2001-247810. Specifically, a polymer solution dissolved in a water-soluble organic solvent, a pigment, and, if necessary, a neutralizing agent are mixed to prepare a solvent dispersion, and the dispersion is developed into an aqueous phase to develop an aqueous suspension. Prepare a suspension. And the water-soluble organic solvent added at the time of solvent dispersion liquid adjustment is distilled off, and a pigment is included with a vinyl polymer particle.

  The neutralizing agent may be appropriately determined. Examples of the alkali include tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide and the like. As the acid, inorganic bases 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 can be used.

  As the organic solvent, water-soluble organic solvents are preferable, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone, diethyl ketone and methyl isobutyl ketone, ethers such as dibutyl ether, tetrahydrofuran and dioxane, and the like. It is done.

  In addition, the process of including the pigment in the polymer can use a disperser. Disperse using a disperser such as a ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc. To do. More preferably, a high-pressure homogenizer that is less likely to be mixed with crushed pieces of the dispersion medium is used.

  The particle size of the vinyl polymer particles thus obtained is preferably about 25 to 250 nm, more preferably the lower limit is about 30 nm and the upper limit is about 175 nm.

Water-insoluble vinyl polymer B
The water-insoluble vinyl polymer B used in the present invention does not contain a pigment obtained by polymerizing a monomer composition comprising (5) a styrene monomer and (6) a monomer copolymerizable with the styrene monomer. Vinyl polymer.

  Monomers copolymerizable with styrene monomers include acrylic esters, methacrylic esters, unsaturated carboxylic acids, hydroxyl group-containing vinyl compounds, aromatic vinyl compounds, unsaturated amides, aminoalkyl acrylates or aminoalkyl methacrylates. Or quaternary chlorides, N-aminoalkyl acrylamides or N-aminoalkyl methacrylamides with methyl halide, ethyl halide, benzyl halide, etc., or methyl halides, ethyl halides, halogenated thereof. Examples include quaternary chlorides such as benzyl, vinyl esters, vinylidene halides, diacrylates, and dimethacrylates.

  Acrylic acid esters include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, iso-amyl acrylate, n-hexyl acrylate, 21-ethyl hexyl acrylate, octyl acrylate, decyl acrylate, dodecyl acrylate , Octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, alkyl esters of 1 to 12 carbon atoms of acrylic acid such as benzyl acrylate, and the like. Examples of the methacrylic acid esters include ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 21-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl. Examples thereof include alkyl esters of 1 to 12 carbon atoms of methacrylic acid such as methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and benzyl methacrylate.

  Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, acrylic anhydride, methacrylic anhydride, maleic anhydride, itaconic anhydride, and fumaric anhydride. Examples of the hydroxyl group-containing vinyl compounds include 21-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate. Examples of the aromatic vinyl compounds include 2-methyl styrene, t-butyl styrene, chlorostyrene, vinyl anisole, vinyl naphthalene, and divinyl benzene. Examples of the unsaturated amides include acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N-one. Examples include methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, and maleic amide.

  Aminoalkyl acrylate or aminoalkyl methacrylates, or quaternary chlorides thereof with methyl halide, ethyl halide, benzyl halide, etc. include N, N monodimethylaminoethyl acrylate, N, N monodimethylaminoethyl methacrylate, N, N monodimethylaminopropyl acrylate, N, N monodimethylaminopropyl methacrylate, N, Nt monobutylaminoethyl acrylate, N, Nt monobutylaminoethyl methacrylate, N, N monomonomethylaminoethyl acrylate, N , N-monomethylaminoethyl methacrylate, etc., or quaternary chlorides, N-aminoalkylacrylamides or N-aminoalkyl methacrylates of these with methyl halide, ethyl halide, benzyl halide, etc. Amides or their quaternary chlorides with methyl halide, ethyl halide, benzyl halide, etc .; N, N monodimethylaminopropyl acrylamide, N, N monodimethylaminopropyl methacrylamide, N, N monodimethylaminoethyl Examples thereof include acrylamide, N, N-dimethylaminoethyl methacrylamide, and the like, or quaternary chlorides thereof using methyl halide, ethyl halide, benzyl halide and the like.

  Examples of vinyl esters include vinyl acetate and vinyl propionate. Examples of the vinylidene halides include vinylidene chloride and vinylidene fluoride. Examples of the diacrylates include polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, and the like. Examples of the dimethacrylates include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,3 butylene glycol dimethacrylate, 1,6 -Hexanediol dimethacrylate, neopentyl glycol dimethacrylate and the like.

  Other monomers include trimethylolpropane trimethacrylate, trimethylol propane triacrylate, tetramethylol methane triacrylate, tetramethylol methane tetraacrylate, allyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyl oxyethyl acrylate, vinyl chloride, Vinyl ether, vinyl ketone, vinyl amide, chloroprene, ethylene, propylene, isoprene, butadiene, vinyl pyrrolidone, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, acrylonitrile, methacrylonitrile, isopropenyl- α, α-dimethylbenzyl isocyanate, a Examples include rilmercaptan. As said other monomer, only 1 type may be sufficient and it can use 2 or more types together. Particularly suitable as the other monomers are methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl. Alkyl esters or hydroxyalkyl esters of acrylic acid or methacrylic acid such as acrylate and 2-hydroxyethyl methacrylate.

  The monomer copolymerizable with the styrene monomer may be used alone or in combination of two or more. In particular, the monomer copolymerizable with the styrene monomer contains at least one selected from unsaturated carboxylic acids, unsaturated amides, and monomers having two or more polymerizable double bonds in the molecule. Is preferred.

  By using the unsaturated carboxylic acid as a monomer (6) copolymerizable with the styrene monomer, the ink storage stability and clogging recovery can be improved. When the total monomer composition is 100 parts by weight, the amount of the unsaturated carboxylic acid added to the monomer composition is preferably 3-8 parts by weight. If the amount of the unsaturated carboxylic acid added is less than 3 parts by weight, the effect on ink storage stability and clogging recovery may be reduced, and if it exceeds 8 parts by weight, the ink viscosity may increase. .

  Examples of monomers having two or more polymerizable double bonds in one molecule include diacrylates, dimethacrylates, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane triacrylate, and tetramethylolmethane tetraacrylate. , Etc., and polyvalent esters of unsaturated carboxylic acids. When the total amount of the monomer composition is 100 parts by weight, the addition amount of the monomer having two or more polymerizable double bonds in one molecule to the monomer composition is preferably 0.3 to 10 parts by weight. When the addition amount of the monomer having two or more polymerizable double bonds in one molecule is less than 0.3 part by weight, the dispersion stability of the fine particles comprising the water-insoluble polymer B is lowered, and the ink composition according to the present invention is reduced. When used as ink-jet ink, the ink discharge port of the ink cartridge tends to be clogged, and the printing stability tends to be inferior. Moreover, when the addition amount of the monomer having two or more polymerizable double bonds in one molecule exceeds 10 parts by weight, unreacted monomer may remain and odor may be generated.

  By using an unsaturated amide as the monomer (6) copolymerizable with the styrene monomer, the ink storage stability and clogging recovery can be improved. When the total amount of the monomer composition is 100 parts by weight, the amount of the unsaturated amide added to the monomer composition is preferably 0.05 to 2 parts by weight. If the addition amount of the wood saturated amide is less than 0.05 parts by weight, the effect on ink storage stability and clogging recovery may be reduced, and if it exceeds 2 parts by weight, the ink viscosity may increase. .

Synthesis of water-insoluble vinyl polymer B The water-insoluble vinyl polymer B used in the present invention is prepared by a known emulsion polymerization method using the styrene monomer (5) and a monomer (6) copolymerizable with the styrene monomer. The copolymer can be prepared directly, or can be produced by finely dispersing a copolymer produced by another polymerization method in a liquid medium based on a mechanical emulsification method.

  As a method using an emulsion polymerization method, there are a method in which various monomers are charged in a batch in the presence of a dispersant and a polymerization initiator, and a method in which polymerization is carried out while continuously supplying monomers. The polymerization at that time is usually carried out in a temperature range of 30 to 90 ° C., and a substantially aqueous dispersion of copolymer particles, generally called an emulsion, and polymer particles B are obtained. The aqueous dispersion of copolymer particles obtained by the emulsion polymerization method is excellent in that it is very stable in a small amount of a dispersant and a particle having a very small particle diameter can be easily obtained.

  Examples of the dispersant used in the emulsion polymerization method include nonionic surfactants, anionic surfactants, nonionic water-soluble polymers, anionic water-soluble polymers, and the like. Can be selected.

  Specific examples of the nonionic surfactant include, for example, polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene oleyl phenyl ether, polyoxyethylene nonyl phenyl ether, oxyethylene / oxypropylene block copolymer, t Examples include octylphenoxyethyl polyethoxyethanol, nonylphenoxyethyl polyethoxyethanol, and the like, and one or more of these can be selected.

  Specific examples of the anionic surfactant include, for example, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium stearate, potassium oleate, Sodium dioctyl sulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium dialkyl sulfosuccinate, sodium stearate, sodium oleate, t-octyl Examples include sodium phenoxyethoxypolyethoxyethyl sulfate, and one or more of these are selected. It can be.

  Nonionic water-soluble polymers include polyvinyl alcohol or derivatives thereof; starch derivatives such as oxidized starch, etherified starch and phosphate esterified starch; polyvinylpyrrolidone derivatives such as polyvinylpyrrolidone copolymerized with polyvinylpyrrolidone or vinyl acetate; Derivatives Cellulose derivatives such as carboxymethyl cellulose and hydroxymethyl cellulose; polyacrylamide or derivatives thereof; polymethacrylamide or derivatives thereof; gelatin, casein and the like can be mentioned, and one or two or more of these can be selected.

  Anionic water-soluble polymers include polyalginic acid and its metal salt, carboxymethylcellulose and its metal salt, polyacrylic acid and its metal salt, polyacrylamide partial hydrolyzate and its metal salt, maleic acid copolymer, lignin sulfone Acids and their metal salts and their derivatives, oxyorganic acids and their metal salts, alkylallyl sulfonic acids and their metal salts, polyoxyalkyl allyl ethers, polyol complexes, higher polyhydric alcohol sulfonic acids and their metal salts, gelatin Examples thereof include water-soluble proteins such as glue, metal salts thereof, and derivatives thereof, and one or more of these can be selected.

  The amount of the dispersant used is not particularly limited, but is usually 0.02 to 20% by weight, more preferably 0.02 to 10% by weight, and most preferably 0.02 to 5% based on the total weight of the monomers to be copolymerized. % By weight.

  As the initiator used for copolymerization, a normal radical initiator can be used, for example, hydrogen peroxide; persulfates such as ammonium persulfate and potassium persulfate; cumene hydroperoxide, t-butyl hydroperoxide, Organic peroxides such as benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, lauroyl peroxide; azobisisobutyronitrile, 2,2′-azobis (2- Amidinopropane) dihydrochloride, 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride, 2,2'-azobis {2- [N- (4-chlorophenyl) amidino] propane} Hydrochloride, 2,2′-azobis {2- [N- (4-hydroxyphenyl) amidino] propane} dihydrochloride, 2 2′-azobis [2- (N-benzylamidino) propane] dihydrochloride, 2,2′-azobis [2- (N-allylamidino) propane] dihydrochloride, 2,2′-azobis {2- [ N- (2-hydroxyethyl) amidino] propane} dihydrochloride, 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2 , 2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide}, 2,2'-azobis [2-methyl-N- [2-hydroxyethyl) propionamide] , 2,2′-azobis (isobutyramide) dihydrate, etc .; or these and metal ions such as iron ions and sodium sulfoxylate, formaldehyde, pyro Examples include redox initiators in combination with reducing agents such as sodium sulfite, sodium hydrogen sulfite, L-ascorbic acid, Rongalite, and the like, and one or more of these can be selected.

  A typical initiator is used in an amount of 0.01-20% by weight based on the total weight of the monomers to be copolymerized.

If necessary, mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, allyl sulfonic acid, methallyl sulfonic acid and allyl compounds such as soda salts thereof can be used as molecular weight regulators. is there. In addition, sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide, potassium hydroxide, magnesium sulfate, potassium sulfate, aluminum sulfate, sodium acetate, magnesium acetate, potassium acetate, ammonia, triethanolamine, diethanolamine are used as pH adjusters as necessary. Monoethanolamine or the like can also be used.

  The glass transition temperature of the water-insoluble vinyl polymer B is preferably 20 to 200 ° C. The blending amount of the monomer composition can be adjusted so that the glass transition temperature is within this range. Specifically, it can be obtained from the DSC curve based on JISK7121.

  The minimum film formation temperature (MFT) of the polymer fine particles comprising the water-insoluble vinyl polymer B is preferably 20 to 200 ° C. Similar to the glass transition temperature, the minimum film forming temperature can be adjusted by blending the monomer composition. In the present specification, the “minimum film formation temperature” means the minimum temperature required for film formation by combining polymer particles. This minimum film formation temperature can be measured by a temperature gradient plate method as described in Soichi Muroi, “Chemistry of Polymer Latex” (1997) and the like. As an example, the minimum film formation temperature of the polymer particles can be measured as follows.

First, an aqueous dispersion of polymer particles is uniformly applied on a PET film so as to have a dry solid content of 5 g / m ² to prepare a measurement sample, and then a silicone release film is applied to the measurement sample. Then, a commercially available laminator is passed at different temperature levels at a speed of 18 cm / min, and the lowest temperature at which a continuous film is considered to be formed is defined as the lowest film formation temperature. Judgment criteria for continuous film formation is that the coating layer is transparent, the coating layer is smooth, and the fallen material from the coating layer obtained by rubbing the surface with a sharp tool is not a discontinuous material, but a continuous film shape. It can be based on satisfying these three items.

  The average particle size of the particles made of the water-insoluble vinyl polymer B needs to be 30 to 60 nm, preferably 35 to 55 nm. When the average particle diameter of the polymer particles is less than 30 nm, the ink viscosity increases. When the average particle diameter exceeds 60 nm, the gloss of the printed surface decreases when printing is performed, and a high-quality printed matter cannot be obtained.

  The particle diameter of the particles composed of the water-insoluble vinyl polymer B is controlled by the amounts of the surfactant and the polymerization initiator used. Increasing the amount of surfactant used decreases the particle size, and decreasing the amount of polymerization initiator decreases the particle size.

Quinacridone Magenta Pigment The ink composition according to the present invention uses a quinacridone magenta pigment as a colorant.

  Ink for ink jet recording having excellent ink reliability and excellent fixability to glossy paper by combining the water-insoluble polymer A containing the quinacridone magenta pigment and the water-insoluble polymer B A composition can be realized.

  As quinacridone magenta pigments, quinacridone magenta pigments may be C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 209, and C.I. I. Pigment violet 19, and one or more of these may be used in combination.

  In the present invention, in addition to the quinacridone-based magenta pigment, it is preferable to further include a pigment derivative having an acid group introduced into the pigment. By using such a pigment derivative having an acid group introduced therein, the dispersibility in the ink composition is further improved, the ink is excellent in reliability, and the fixing property is improved even on glossy paper. .

A pigment derivative is a compound in which an acid group is introduced into an organic pigment. A pigment derivative is used together with a quinacridone pigment in order to enhance the dispersion stability, print density, and hiding property of an aqueous dispersion or ink. As the acid group, for example, —COOM (wherein M represents a hydrogen atom, a typical metal, an ammonium group or an organic ammonium group; the same shall apply hereinafter), —SO ₃ M, —SO ₂ M, —RSO ₂ M ( in the formula, R is an alkyl group of carbon 1-12, have a phenyl group or a substituted group may have a substituent indicates also a naphthyl group or less the _{same), -. PO 3 HM,} - PO ₃ M, and the like. these may be used alone or in combination of two or more. Among these, —SO ₃ M is most preferable from the viewpoint of ink reliability.

  Examples of the quinacridone sulfonic acid compound include quinacridone sulfonic acids and metal salts thereof such as sodium, aluminum, and calcium, ammonium, octadecyl ammonium, didodecyl ammonium, dimethyl octadecyl ammonium, dimethyl dioctadecyl ammonium, benzyldimethyl octadecyl ammonium, and the like. An ammonium salt etc. are mentioned. Among these, metal salts such as aluminum salt and calcium salt of quinacridone sulfonic acid are preferable, and aluminum salt is more preferable. The quinacridone sulfonic acid compound can be obtained by treating quinacridone with fuming sulfuric acid and sulfonating it by a known method.

  The amount of the pigment derivative with respect to 100 parts by weight of the quinacridone pigment is preferably 1 to 10 parts by weight, more preferably 2 to 8 parts by weight, still more preferably 3 to 6 parts by weight, from the viewpoint of enhancing the dispersion stability.

  In the present invention, a mixture of a quinacridone pigment and a pigment derivative (hereinafter simply referred to as “mixture”) is preferable. The mixture may be prepared by bringing a pigment derivative into contact with a quinacridone pigment in the presence or absence of a solvent and mixing the mixture, according to the method described in paragraph [0021] of JP-A-11-49974. It may be prepared by processing. The mixture only needs to be mixed, and may be mixed non-uniformly.

  The content of the quinacridone-based magenta pigment is preferably 50 to 1000 parts by weight, preferably 80 to 800 parts by weight with respect to 100 parts by weight of the resin solid content of the polymer, from the viewpoint of printing density and ease of inclusion in the polymer particles. Is more preferable, and 100 to 600 parts by weight is particularly preferable.

Water and other ingredients
The ink composition of the water present invention comprises water as a main solvent. As the water, pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water can be used. In addition, the use of water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold or bacteria can be prevented when the ink composition is stored for a long period of time.

pH Adjusting Agent The ink composition according to the present invention preferably further comprises a pH adjusting agent. Specific examples of pH adjusters include hydroxides of alkali metals such as lithium hydroxide, potassium hydroxide and sodium hydroxide, amines such as ammonia, triethanolamine, tripropanolamine, diethanolamine and monoethanolamine. More preferred are those selected from the group consisting of triethanolamine, tripropanolamine, and mixtures thereof.

  In the present invention, the pH of the ink composition is preferably 8.0 to 11. By adjusting the pH of the ink composition in such a range, a more excellent gloss feeling can be realized. In order to bring the ink composition to a pH in the above range, it can be suitably adjusted by using the above pH adjuster.

Water-soluble organic solvent The ink composition of the present invention preferably further comprises a water-soluble organic solvent. The water-soluble organic solvent mainly functions as a penetrating agent, a moisturizing agent, a viscosity adjusting agent or the like of the ink composition.

  Specific examples of the water-soluble organic solvent include monohydric alcohols such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, iso-pentanol, and n-pentanol. , Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol Mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol Mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, And glycol monoalkyl ethers such as propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, and dipropylene glycol mono-iso-propyl ether. be able to.

Glycol ether mono-n-butyl ether According to a preferred embodiment of the present invention, for example, glycol mono-n-butyl ether is particularly preferred.

  Examples of such glycol mono-n-butyl ether include ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, or dipropylene. A thing chosen from glycol mono-n-butyl ether is mentioned as a preferable thing. These may be used alone or in combination of two or more.

  The addition amount of the water-soluble organic solvent is preferably from 0.25% by weight to 15% by weight with respect to the total amount of the ink, a more preferable upper limit is 10% by weight, and a more preferable lower limit is 0.5. % By weight.

Surfactant The ink composition according to the present invention preferably comprises a surfactant. Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, because an ink composition with less foaming or foaming is obtained. Nonionic surfactants are preferred. Specific examples of nonionic surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl Ethers such as allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, polyoxyethylene distearic acid ester , Sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene Fluorinated surfactants such as ester monooleate, polyoxyethylene stearate, etc., other fluorine alkyl esters, perfluoroalkyl carboxylates, etc., especially acetylene glycol surfactants and acetylene alcohol surfactants Agents are preferred. When these surfactants are added to the ink composition, they are preferable because they have less foaming properties and have an excellent antifoaming function. Specific examples of the acetylene glycol surfactant and the acetylene alcohol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne- 3,6-diol, 3,5-dimethyl-1-hexyn-3ol, etc. are available, but are also commercially available. For example, Surfynol 104, 82 manufactured by Air Products and Chemicals, Inc. 465, 485, TG, Olphine STG manufactured by Nisshin Chemical Co., Ltd., Olphine E1010, Surfynol 104PG50 and the like.

  The addition amount of the surfactant is preferably 0.05% by weight or more and 3% by weight or less with respect to the total amount of the ink composition, the more preferable upper limit value is 2.0% by weight, and the preferable lower limit value is 0.1% by weight.

1,2-Alkanediol In the present invention, the ink composition preferably further comprises 1,2-alkanediol.

  Such 1,2-alkanediol is preferably selected from the group consisting of 1,2-alkanediols having 4 to 10 carbon atoms. In this case, 1,2-alkanediol may be mixed and added.

  In a preferred embodiment of the invention, the 1,2-alkanediol is a group consisting of 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and mixtures thereof. More selected. These are more preferable from the viewpoint of excellent permeability to a recording medium.

  In a more preferred embodiment of the present invention, the 1,2-alkanediol is preferably 1,2-hexanediol or 1,2-pentanediol, more preferably 1,2-hexanediol. .

  The addition amount of 1,2-alkanediol is preferably 0.25 wt% or more and 15 wt% or less with respect to the total amount of the ink composition, and a more preferable upper limit is 10 wt%. Alkanediol, more preferably the lower limit is 0.5% by weight.

Other Components According to a preferred embodiment of the present invention, the ink composition preferably comprises a polyol in order to prevent clogging of the nozzles of the ink jet recording head. Such polyols are preferably water-soluble polyols, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, 1, 3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, mesoerythritol, pentaerythritol, thiodi Glycol, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, pentaerythritol And the like.

  Further, lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and ε-caprolactam, and ureas such as urea, thiourea, ethylene urea, and 1,3-dimethylimidazolidinone can also be used. Furthermore, as monosaccharides, disaccharides, oligosaccharides and polysaccharides, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotri Aose can also be added. Furthermore, derivatives of these saccharides can also be used, and examples thereof include the reducing sugars, oxidized sugars, amino acids, and thio sugars of the aforementioned sugars. Of these, sugar alcohols are particularly preferred, and specific examples include maltitol and sorbit. Moreover, you may obtain and use HS-500, HS-300, etc. by the Hayashibara biochemical research laboratory which are commercial items. These may be used alone or in combination of two or more.

  The addition amount of these clogging prevention components is preferably 5% by weight or more and 40% by weight or less with respect to the total amount of the ink composition, a more preferable upper limit value is 30% by weight, and a more preferable lower limit value is 10% by weight.

  These components are preferably added together with other ink additives in such an amount that the ink viscosity is 25 cPs or less at 25 ° C.

  The ink composition according to the present invention may be added with a pH buffer, an antioxidant, an ultraviolet absorber, an antiseptic or antifungal agent, a chelating agent, and the like, if necessary.

  Specific examples of the pH buffering agent include collidine, imidazole, phosphoric acid, 3- (N-morpholino) propanesulfonic acid, tris (hydroxymethyl) aminomethane, boric acid and the like.

  Specific examples of the antioxidant or ultraviolet absorber include allophanates such as allophanate and methyl allophanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret, L-ascorbic acid and its salts, etc., manufactured by Ciba Geigy Examples include Tinuvin 328, 900, 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024, or lanthanide oxides.

  Specific examples of preservatives or fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3- ON (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN manufactured by Avecia) and the like. Specific examples of the chelating agent include ethylenediaminetetraacetic acid (EDTA).

Preparation of Ink Composition The ink composition according to the present invention may be prepared by supplying the above-described components to a dispersing / mixing machine (for example, a ball mill, a sand mill, an attritor, a basket mill, a roll mill, etc.) and dispersing them. . According to a preferred embodiment of the present invention, it is preferable to filter the ink stock solution obtained by the above-described dispersing / mixing device using a filter such as a membrane filter or a mesh filter to remove coarse particles.

Inkjet recording method and apparatus An inkjet recording method in which the ink composition according to the present invention is used discharges ink composition droplets and attaches the droplets to a heated recording medium for printing. As an example of a method for ejecting ink composition droplets, for example, an electrostrictive element is used to convert an electrical signal into a mechanical signal, and ink stored in the nozzle head portion is intermittently ejected onto the surface of the recording medium. A method of recording characters and symbols, ink heated in the nozzle head portion is heated rapidly at a location very close to the discharge portion, bubbles are generated, and the ink is intermittently discharged by the volume expansion caused by the bubbles, and characters are printed on the surface of the recording medium. And a method of recording symbols. According to a preferred embodiment of the present invention, the ink composition according to the present invention is preferably used in an ink jet recording method using an electrostrictive element. The ejection of the ink composition droplets is preferably performed by a recording head that ejects ink droplets using the mechanical action of the piezoelectric element.

  Further, according to the present invention, a recorded matter recorded by the recording method is also provided.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

Preparation of water-insoluble vinyl polymer A A monomer having the following composition was prepared.

Polypropylene glycol monomethacrylate 15% by weight
(In formula (I), o = 9, R ₁ is a methyl group, and R ₂ is a hydrogen atom. Trade name: BLEMMER PP-500, manufactured by NOF Corporation)
Polyethylene glycol monomethacrylate 10% by weight
(In the formula (II), o = 23, a compound in which R ₁ and R ₂ are methyl groups. Trade name: NK ESTER M230G, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Methacrylic acid 14% by weight
46% by weight of styrene monomer
15% by weight of styrene macromer
(Styrene-acrylonitrile copolymer macromer, number average molecular weight: 6,000, polymerizable functional group: methacryloyl group, trade name: AN-6, manufactured by Toagosei Co., Ltd.)
A reaction vessel was charged with 20 parts by weight of methyl ethyl ketone, 0.03 part by weight of a polymerization chain transfer agent (2-mercaptan etarule), and 10% by weight of the total amount of the above monomers, and mixed. Thereafter, the container was replaced with nitrogen gas. On the other hand, the dropping device was filled with the remaining 90% by weight of the monomer composition.

  Next, 0.27 parts by weight of a polymerization chain transfer agent (2-mercaptan ethanol), 60 parts by weight of methyl ethyl ketone, and 1.2 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) are then added to the dropping apparatus and mixed. did. Thereafter, the dropping device was replaced with nitrogen gas.

  The temperature of the mixture in the reaction vessel was raised to 65 ° C. with stirring in a nitrogen atmosphere, and the mixture in the dropping apparatus was dropped into the reaction vessel over 3 hours. Two hours after the completion of dropping at 65 ° C., a solution in which 0.3 part by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 5 parts by weight of methyl ethyl ketone was added. The mixture was aged at 65 ° C. for 2 hours and further at 70 ° C. for 2 hours to obtain a polymer solution.

  A part of the polymer solution obtained as described above was distilled off under reduced pressure to remove the solvent and then isolated to obtain a polymer solution.

  The weight average molecular weight was determined by gel permeation chromatography using polystyrene as a standard substance and phosphoric acid having a concentration of 60 mmol / L and dimethylformamide containing 50 mmol / L of lithium bromide as a solvent. As a result, the weight average molecular weight was 70,000.

Preparation of Pigment Dispersion A Under low temperature conditions of 5 to 10 ° C., 2,9-dichloroquinacridone pigment (CI Pigment Red 202: manufactured by Ciba Geigy) was added to the fuming sulfuric acid, and the reaction was performed. Poured into ice water. The obtained suspension was filtered and further washed to obtain a suspension of 2,9-dichloroquinacridonesulfonic acid.

  3 weights of 2,9-dichloroquinacridonesulfonic acid plus neutralizing equivalent of aluminum hydroxide per 100 weight parts of unsubstituted quinacridone pigment (CI Pigment Violet 19: manufactured by Dainippon Ink & Chemicals, Inc.) The parts were mixed, washed with water, and dried to obtain a quinacridone pigment mixed with 2,9-dichloroquinacridonesulfonic acid aluminum salt.

  On the other hand, 4 parts by weight of each polymer obtained by drying under reduced pressure from the above water-insoluble polymer solution A was dissolved in 13.3 parts by weight of methyl ethyl ketone, and a neutralizing agent (20% aqueous sodium hydroxide solution) was placed therein. A fixed amount was added to neutralize the salt-forming groups.

  Next, 16 parts by weight of quinacridone pigment mixed with the aluminum salt of 2,9-dichloroquinacridone sulfonic acid obtained above was added to this polymer solution, and dispersed to an average particle size of 130 nm with a kneader while adding water.

  After 120 parts by weight of ion-exchanged water was added to the kneaded product obtained above and stirred, 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%. A weight percent pigment dispersion A was obtained. The average particle diameter of the polymer particles in the pigment dispersion A was 120 nm as a result of measurement using a Coulter counter N4 (manufactured by Coulter).

Preparation of Pigment Dispersion B 5 parts by weight of the vinyl polymer obtained above was dissolved in 45 parts by weight of methyl ethyl ketone, and a predetermined amount of a neutralizing agent (20% aqueous sodium hydroxide solution) was added thereto to form a salt-forming group. Then, 15 parts by weight of an unsubstituted quinacridone pigment (CI Pigment Violet 19: manufactured by Dainippon Ink & Chemicals, Inc.) was added as a pigment and kneaded in a bead mill for 2 hours.

  After 120 parts by weight of ion-exchanged water was added to the kneaded product obtained above and stirred, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was further removed to obtain a solid content concentration of 20%. A weight percent pigment dispersion B was obtained. The average particle size of the polymer particles in the pigment dispersion B was 130 nm as a result of measurement using a Coulter Counter N4 (trade name) (manufactured by Coulter).

Preparation of Pigment Dispersion C C. 15 parts of 2,9-dimethylquinacridone pigment (CI Pigment Red 122: Dainippon Ink Co., Ltd.) is mixed with 400 parts of quinoline, and Eiger Motor Mill M250 (Eiger Japan Co., Ltd.) is used. The sized particles were dispersed for 2 hours under the conditions of a bead filling rate of 70% and a rotational speed of 4500 rpm. The mixed liquid of the pigment paste and the solvent in which the particle size was dispersed was transferred to an evaporator, heated to 120 ° C. while reducing the pressure to 30 mmHg or less, and after the water contained in the system was distilled off as much as possible, the temperature was controlled to 160 ° C. Next, 20 parts of a sulfonated pyridine complex was added and reacted for 8 hours. After completion of the reaction, the mixture was washed several times with excess quinoline, poured into water, sodium hydroxide was added as a neutralizing agent, and a paint shaker (using glass beads; beads) Dispersion was performed until the average particle diameter (secondary particle diameter) of the pigment became 95 nm using a filling ratio = 60%; media diameter = 1.7 mm). The obtained dispersion stock solution was diluted with ultrapure water to a pigment concentration of 20% by weight to obtain a pigment dispersion C.

Preparation of water-insoluble vinyl polymer B The synthesis was performed using a flask equipped with a stirrer, a nitrogen introduction tube, a cooling tube, and two dropping funnels. In one of the two dropping funnels, an emulsified liquid obtained by emulsifying each of the mixed liquids of Production Examples 1 to 6 shown in Table 1 below with a homomixer is put, and the other dropping funnel has persulfuric acid as a catalyst. A solution prepared by dissolving 0.3 part of potassium in 5 parts of water was added. In the flask, 0.2 part of sodium lauryl sulfate was dissolved in 190 parts of water, the inside of the flask was put into a nitrogen atmosphere, the flask was heated to 70 ° C. with a hot water bath, and stirred at 250 rpm, and two dropping funnels were used. The solution inside was dropped into the flask over 4 hours to carry out the reaction. After completion of dropping, the mixture was further stirred for 4 hours, cooled and neutralized with an aqueous sodium hydroxide solution to obtain polymer particles B having a nonvolatile content of 30%. The average particle diameter of the polymer particles was 50 nm as a result of measurement using a Coulter Counter N4 (manufactured by Coulter). The results of measuring the minimum film formation temperature are shown in Table 1.

Preparation of Ink Composition According to the composition shown in Table 2 below, each component was mixed and stirred for 2 hours. Then, it filtered using the membrane filter (brand name) (made by Nippon Millipore Limited) of about 8 micrometers of hole diameters, and prepared the magenta ink. In Table 2, the amount of each composition added is% by weight.

Evaluation of ink composition (1) Glossiness Printing was performed using an inkjet printer PX-A550 (manufactured by Seiko Epson Corporation). The magenta ink cartridge for this printer (Seiko Epson, model number: ICM31) was filled with the ink compositions of Examples and Comparative Examples, respectively, and PM photographic paper (trade name) (Seiko Epson, model number: KA420PSK) On the other hand, a solid image with gradation was printed at a resolution of 1440 dpi to obtain a recorded matter. The obtained recorded matter was allowed to stand at room temperature for 1 day, and then the 20 ° gloss of the highest density portion was measured using a gloss meter GM-268 (manufactured by Konica Minolta).

The measurement results were evaluated based on the following criteria.
A: When 20 ° gloss is 50 or more B: When 20 ° gloss is 40 or more and less than 50 C: When 20 ° gloss is less than 40 The results are as shown in Table 3 below.

(2) Fixing property The back side of the same paper was overlapped on the recorded matter obtained above, and the printed surface was rubbed 20 times with a weight of 200 g / A4. The obtained recorded matter was evaluated based on the following criteria.
A: No rubbing traces B: Some rubbing traces but little concern C: Rubbing traces are conspicuous The results are shown in Table 3 below.

(3) Discharge stability A solid and a pattern were continuously printed at room temperature using the cartridge and the ink jet printer. The number of cleanings of the printer nozzle that was performed as a return operation to normal printing when ink dots were missing or flying bent within 100 pages of printing was measured and evaluated based on the following criteria.
A: Returned after cleaning 0 times B: Returned after cleaning 1 or 2 times C: Returned after cleaning 3 or 4 times D: Returned after cleaning 5 times or more The results were as shown in Table 3 below.

(4) Storage stability The ink composition was placed in an aluminum pack and left in a 70 ° C. environment for one week in a state where the ink composition was put in 50 g. After leaving, the presence or absence of foreign matter (sediment) was confirmed. Moreover, changes in physical properties (viscosity, surface tension, pH, particle diameter of resin particles) were further confirmed for those in which no foreign matter was generated.

The evaluation criteria were as follows.
A: No foreign matter is generated, and there is no change in physical properties.
B: No foreign matter is generated, but the physical properties slightly change.
C: Foreign matter is generated or the physical properties are remarkably changed.
The results were as shown in Table 3 below.

(5) Clogging recovery property Using the above inkjet printer and cartridge, printing continuously for 10 minutes, and after confirming that all nozzles are discharging normally, in order to accelerate the drying state at the nozzles, The ink cartridge was removed and the recording head was removed from the head cap and left in an environment of 40 ° C. and 20% RH for one week.

After leaving, the cleaning operation was repeated until all nozzles ejected at the same level as the initial stage, and the ease of recovery was evaluated according to the following criteria.
A: Recovered to the same level as the initial stage by one or two cleaning operations.
B: It recovered to the same level as the initial stage after 3 or 4 cleaning operations.
C: Recovered to the same level as the initial stage after 4 or 5 cleaning operations.
D: It does not recover after a realistic number of cleaning operations.
The results were as shown in Table 3 below.

Claims (17)

  It comprises at least a quinacridone-based magenta pigment, a water-insoluble vinyl polymer A containing the pigment and capable of dispersing the pigment in the ink composition, a water-insoluble vinyl polymer B not containing the pigment, and water. Ink composition. The water-insoluble vinyl polymer A is
(1) a polyoxyalkylene group-containing monomer;
(2) a salt-containing group-containing monomer;
(3) a macromer having a number average molecular weight of 500 to 500,000,
(4) The vinyl polymer obtained by polymerizing a monomer composition comprising the polyoxyalkylene group-containing monomer, the salt-forming group-containing monomer, and a monomer copolymerizable with the macromer. Ink composition. The water-insoluble vinyl polymer B is
(5) a styrene monomer;
(6) a monomer copolymerizable with the styrene monomer;
The ink composition according to claim 1, which is a vinyl polymer obtained by polymerizing a monomer composition comprising The polyoxyalkylene group-containing monomer is
Formula (I):

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkylphenyl group having 1 to 9 carbon atoms, and o is 1 to 30. Represents a number.)
Monomer A1 represented by
Formula (II):

(In the formula, R ¹ , R ² and o represent the same meaning as defined in formula (I), p represents a number of 1 to 30, and the oxyethylene group and oxypropylene group in [] are block additions. Or any of random addition.) Monomer A2 represented by formula (III):

(In the formula, R ¹ , R ² and o have the same meaning as defined in formula (I).)
The ink composition according to claim 2 or 3, comprising at least one monomer selected from monomers A3 represented by formula (1). The water-insoluble vinyl polymer A is
5 to 45% by weight of the monomer (1),
3 to 40% by weight of the monomer (2),
0.1 to 40% by weight of the macromer (3),
The ink composition according to any one of claims 1 to 4, wherein the monomer (4) is polymerized with 0 to 87% by weight.   The ink composition according to any one of claims 2 to 5, wherein the macromer (3) is a styrenic macromer having a polymerizable functional group at a terminal.   The ink composition according to any one of claims 1 to 6, wherein the water-insoluble vinyl polymer B is in the form of polymer particles having an average particle diameter of 30 to 60 nm.   The ink composition according to any one of claims 1 to 7, wherein a minimum film-forming temperature of the water-insoluble vinyl polymer B is 20 ° C or higher.   The ink composition according to any one of claims 3 to 8, wherein the monomer (6) copolymerizable with the styrene monomer comprises an unsaturated carboxylic acid.   The ink composition according to claim 8, wherein the unsaturated carboxylic acid is contained in an amount of 3 to 8 parts by weight with respect to 100 parts by weight of the monomer composition.   The ink composition according to any one of claims 3 to 10, wherein the monomer (6) copolymerizable with the styrene monomer comprises a monomer having two or more double bonds polymerizable in one molecule. object.   The ink composition according to any one of claims 3 to 11, wherein the monomer (6) copolymerizable with the styrene monomer comprises an unsaturated amide compound.   The quinacridone-based magenta pigment is C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 209, and C.I. I. The ink composition according to any one of claims 1 to 12, which is one or more pigments selected from the group consisting of CI pigment violet 19.   The ink composition according to claim 1, further comprising a pigment derivative obtained by introducing an acid group into an organic pigment.   The ink composition according to claim 14, wherein the pigment derivative is a quinacridone sulfonic acid compound.   An ink jet recording method for performing printing by discharging droplets of an ink composition and attaching the droplets to a recording medium, wherein the ink composition according to any one of claims 1 to 15 is used. An ink jet recording method using   A recorded matter recorded by the ink jet recording method according to claim 16.