JP2006008919A - Ink composition, method of imaging and recorded matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high quality image recording ink composition which is easy-to-handle and safe, and does not smell bad, exhibits good stability in the dispersibility and the storage of the dispersion and is excellent in jetting stability, color development, hue, ink penetration to photo paper, water resistance after printing and light fastness, ozone resistance and scratch resistance necessary for image storage. <P>SOLUTION: The ink composition contains a hydrophobic ethylenic monomer having a hydrogen-bondable structural portion (at least one of an amide bond, a urethane bond, a glycidyl group and a hydroxy group) and the polymer of which, after polymerized, has an oxygen permeation coefficient of ≤2.6×10<SP>-13</SP>[m<SP>3</SP>(STP)×m/(s×m<SP>2</SP>×kPa)] and an oil-soluble compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink composition containing a specific monomer, an image forming method using the same, and a recorded matter.

  In recent years, with the spread of computers, ink jet printers are widely used not only in offices but also in homes for printing on paper, films, cloths, and the like. As inks for inkjet recording, oil-based inks, water-based inks, and solid inks are known, but among these, water-based inks are advantageous in terms of manufacturability, handleability, odor, safety, etc. Water-based ink has become mainstream.

However, since many of the water-based inks use water-soluble dyes that dissolve in a molecular state, there are advantages that transparency and color density are high, but the water resistance is poor because the dyes are water-soluble. When printing on paper, bleeding (bleeding) occurs and the printing quality is remarkably deteriorated, light resistance is poor, and furthermore, a recording paper (hereinafter referred to as “photo quality paper”) provided with an ink receiving layer containing porous inorganic fine particles on the surface. However, the image storage stability is significantly deteriorated due to the influence of an oxidizing gas (SO _x , NO _x , ozone, etc.).

Therefore, water-based inks using pigments and disperse dyes have been proposed for the purpose of solving the above problems (see Patent Document 1).
However, in the case of these water-based inks, although the water resistance is improved to some extent, it is difficult to say that it is sufficient, and the storage stability of the dispersion of pigments and disperse dyes in the water-based ink is lacking, which causes clogging at the ink discharge port. There are problems such as easy. Furthermore, in photographic image quality paper, inks using the pigments and dyes have poor permeability, and there is a problem that the pigments and dyes are easily peeled off from the surface when rubbed by hand.

On the other hand, a method of encapsulating an oil-soluble dye in a polymer has been proposed (for example, see Patent Documents 2 and 3). However, in the case of ink jet ink obtained by this method, the color tone is insufficient, the color reproducibility is not sufficient, especially the image durability due to an oxidizing gas or the like is not sufficient, and further printing on photographic quality paper is possible. In such a case, the scratch resistance is not sufficient.
Further, inks excellent in colorability and scratch resistance have been proposed by introducing a salt-forming group and a polyalkylene oxide group into the polymer (see, for example, Patent Document 4), but the scratch resistance by fingers is good. However, a high level of scratch resistance such as an eraser rub is insufficient.
Furthermore, a method for improving color tone and scratch resistance by using a high-boiling organic solvent and a dye has been proposed (see, for example, Patent Document 5), but this is not necessary when high level image durability is required. It was enough.

As described above, it has handleability, odor, and safety, and is excellent in dispersion stability and storage stability of the dispersion. Therefore, when applied to ink, there is no clogging at the nozzle tip, resulting in ejection stability. Excellent, no paper dependency, excellent color development and color tone (hue), excellent ink penetration even when using the above photographic quality paper, water resistance after printing, especially image storage stability (especially light resistance, ozone resistance) ), An ink composition that has excellent scratch resistance and enables high-density and high-quality recording has not yet been provided.
JP-A-56-157468 JP 58-45272 A JP 62-241901 A Japanese Patent Laid-Open No. 2001-123097 JP 2001-262018 A

  The present invention has been made in view of the above problems, and its purpose is to provide handling properties, odor, safety, excellent dispersion stability and storage stability of the dispersion, and clogging at the nozzle tip. Excellent discharge stability, excellent color development, color tone (hue), excellent ink penetration even when using the above photographic quality paper, water resistance after printing, especially image storage (especially light resistance, ozone resistance) And an image forming method using this ink and a recorded matter recorded by this image forming method.

In view of such circumstances, the present inventors have conducted extensive research and found that the oxygen permeability coefficient of the polymer after polymerization was 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)]. The present invention has been completed by finding that the following ink composition containing a hydrophobic ethylenically unsaturated monomer can solve the above-mentioned problems.
That is, the present invention provides the following.

<1> The polymer after polymerization contains a hydrophobic ethylenically unsaturated monomer having an oxygen permeability coefficient of 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)] or less. An ink composition.

  <2> The ink composition according to <1>, wherein the hydrophobic ethylenically unsaturated monomer has a structural portion capable of taking a hydrogen bond.

  <3> The ink composition according to <1> or <2>, wherein the hydrophobic ethylenically unsaturated monomer has one or more selected from an amide bond, a urethane bond, a glycidyl group, and a hydroxyl group.

  <4> The ink composition according to <1>, <2> or <3>, further comprising an oil-soluble compound and a polymerization initiator.

  <5> The ink composition according to <4>, wherein a liquid containing a hydrophobic ethylenically unsaturated monomer, an oil-soluble compound, and a polymerization initiator is emulsified and dispersed in an aqueous medium.

  <6> The ink composition according to <4> or <5>, wherein the oil-soluble compound is an oil-soluble dye.

  <7> The ink composition according to <6>, wherein the oxidation potential of the oil-soluble dye is nobler than 1.0 V (vs SCE).

  <8> A step of recording an image of the ink composition according to any one of <1> to <7> on a recording material by an ink jet recording method, and then a step of polymerizing a hydrophobic ethylenically unsaturated monomer. An image forming method.

  <9> A recorded matter recorded by the image forming method according to <8>.

  The ink of the present invention does not cause clogging at the nozzle tip, and is excellent in water resistance, scratch resistance and light resistance when printed at a low output.

The ink composition of the present invention is a hydrophobic ethylenically unsaturated monomer having an oxygen permeability coefficient of 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)] or less after polymerization. And further contains an oil-soluble compound and a polymerization initiator, if necessary.

[Hydrophobic ethylenically unsaturated monomer]
The hydrophobic ethylenically unsaturated monomer (hereinafter sometimes referred to as this monomer) used in the present invention is a compound having a polymerizable ethylenic double bond that is solidified by application of energy such as ultraviolet rays, heat, or an electron beam. It is. Hydrophobic means having a solubility of 10% or less in water, and preferably having a solubility of 3% or less. The monomer may be a so-called monofunctional compound having one ethylenically unsaturated group (hereinafter referred to as a monofunctional monomer) or a bifunctional or higher compound (hereinafter referred to as a polyfunctional monomer). Alternatively, one or more of a monofunctional monomer and a polyfunctional monomer may be used in combination. The monomer type can be selected as appropriate for the purpose of controlling the viscosity of the colored fine particles and the physical properties of the polymer after polymerizing the monomer (compatibility with oil-soluble dye, strength, adhesion to the substrate, etc.). .

  Examples of the polymerizable group include an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, and an internal double bond group (such as maleic acid). Among them, an acryloyl group and a methacryloyl group are excellent in polymerization, An acryloyl group is particularly preferable because it can be cured with low energy.

  Polyfunctional monomers include vinyl group-containing aromatic compounds, acrylates (or methacrylates) which are esters of dihydric or higher alcohols and acrylic acid (or methacrylic acid), divalent or higher amines and acrylic acid or methacrylic acid. Acrylamide (or methacrylamide), which is an amide, and ester or polycaprolactone obtained by combining polybasic acid and dihydric alcohol, polyester acrylate in which acrylic acid or methacrylic acid is introduced, alkylene oxide and polyhydric alcohol Polyether acrylate in which acrylic acid or methacrylic acid is introduced into the resultant ether, acrylic acid or methacrylic acid is introduced into the epoxy resin, or an epoxy obtained by reacting a dihydric or higher alcohol with an epoxy-containing monomer. Siacrylate, urethane acrylate with urethane bond, amino resin acrylate, acrylic resin acrylate, alkyd resin acrylate, spirane resin acrylate, silicone resin acrylate, reaction product of unsaturated polyester and photopolymerizable monomer, and wax and polymerization The reaction product of a photopolymerizable monomer is preferable, and the reaction product of an acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane acrylate, acrylic resin acrylate, silicone resin acrylate, unsaturated polyester and the photopolymerizable monomer is preferable. Particularly preferred are acrylates, polyester acrylates, polyether acrylates, epoxy acrylates and urethane acrylates.

  Examples of polyfunctional monomers include divinylbenzene, trivinylcyclohexane, ethylene glycol dimethacrylate, 1,3-butanediol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, Pentaerythritol hexaacrylate, 1,6-acryloylaminohexane, hydroxypivalate ester neopentyl glycol diacrylate, having a (meth) acryloyl group at the end of the molecular chain of a polyester having a molecular weight of 500 to 30,000 consisting of a dibasic acid and a dihydric alcohol Polyester acrylate, polyethylene glycol diacrylate, epoxy having a molecular weight of 450 to 30000 containing a bisphenol (A or S, F) skeleton Acrylate, epoxy acrylate having a molecular weight of 600 to 30000 containing a skeleton of phenol novolac resin, a reaction product of a polyisocyanate having a molecular weight of 350 to 30000 and a (meth) acrylic acid monomer having a hydroxyl group, and a urethane having a urethane bond in the molecule Examples include modified products.

  Monofunctional monomers include substituted or unsubstituted (meth) acrylates, substituted or unsubstituted styrenes, substituted or unsubstituted acrylamides, vinyl group-containing monomers (vinyl esters, vinyl ethers, N-vinyl amide, etc.), ( (Meth) acrylic acid, etc., and substituted or unsubstituted (meth) acrylate, substituted or unsubstituted acrylamide, vinyl esters and vinyl ethers are preferred, substituted or unsubstituted (meth) acrylate, substituted or unsubstituted Acrylamide is particularly preferred. Examples of monofunctional monomers include n-butyl acrylate, t-butyl acrylate, t-octyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-dodecyl acrylate, benzyl acrylate, 1H, 1H, 2H, 2H- Perfluorohexyl acrylate, n-butyl methacrylate, sec-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-dodecyl methacrylate, octadecyl methacrylate, benzyl methacrylate, hydroxybutyl acrylate, 2-chloroethyl acrylate, glycidyl Acrylate, allyl acrylate, diphenyl-2-methacryloyloxyethyl phosphate, N-butoxymethylacrylamide, t-butyl Acrylamide, t-octylacrylamide, phenylacrylamide, 2-hydroxybutyl vinyl ether, styrene, methylstyrene, p-chlorostyrene, pt-butylstyrene, methoxystyrene, vinyl acetate, vinyl caproate, vinyl benzoate, polydimethylsiloxane Examples include monoacrylate.

The hydrophobic ethylenically unsaturated monomer used in the present invention has a polymer oxygen permeability coefficient of 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)] or less, It is preferably 2.3 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)] or less.
In the present invention, the oxygen permeability coefficient of the polymer after polymerization is a value measured using a known oxygen electrode method shown below.
Methods for measuring the oxygen permeability coefficient of organic compounds are described in the book, and are described in detail, for example, on pages 283 to 323 of Polymers and Moisture (edited by the Society of Polymer Science, Kobo Shobo, published in 1972). In the present invention, the oxygen permeation coefficient was calculated using the oxygen electrode method in which fluid compounds can be measured. For the measurement, an oxygen analyzer (model 3600, diaphragm 2956A 25 μm, manufactured by Orbis Fair Laboratories Japan Inc.) was used. The compound to be measured was fixed in a uniform film on the detection head under the conditions of 25 degrees and 50% humidity, and the oxygen transmission coefficient was calculated by calibrating the oxygen concentration detected by the electrode using a standard transmission sample.

  In order to reduce the oxygen permeability coefficient of a polymer after polymerization of a hydrophobic ethylenically unsaturated monomer, the monomer has a structural site capable of taking a hydrogen bond, particularly from an amide bond, a urethane bond, a glycidyl group and a hydroxyl group. It is preferable to have one or two or more selected. Specifically, what has 1 type, or 2 or more types chosen from group represented with the following general formula is preferable.

(In the formula, each R ₁ independently represents a linear or branched alkylene group or alkyleneoxy group which may have a substituent, and R ₂ represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. Or a cyano group)
Examples of monomers that reduce the oxygen permeability coefficient of the polymer after polymerization include N-monosubstituted acrylamide, N-disubstituted acrylamide, N-monosubstituted methacrylamide, N-disubstituted methacrylamide, glycidyl acrylate, glycidyl methacrylate, and hydroxy. Ethyl acrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl acrylate glycidyl ether, 2-chloroethyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, 2,3-dihydroxypropyl methacrylate, 2-hydroxy One or more selected from butyl acrylate, 2-hydroxypropyl acrylate and the like are preferable.

  Specific examples of polymers synthesized from the monomers used in the present invention are listed. The ratio in parentheses means the mass ratio. The present invention is not limited to these specific examples.

PA-1) Copolymer of n-butyl acrylate / 2-hydroxyethyl acrylate (70:30) Mw = 24300 Oxygen transmission coefficient: 1.05 × 10 ^-13 [m ³ (STP) ・ m / (s ・ m ²・ kPa ]]
PA-2) n-butyl acrylate / 4-hydroxybutyl acrylate copolymer (70:30) Mw = 22200 Oxygen transmission coefficient: 1.26 × 10 ^-13 [m ³ (STP) · m / (s · m ² · kPa) ]
PA-3) n-Butyl acrylate / 2-chloroethyl acrylate copolymer (70:30) Mw = 30600 Oxygen transmission coefficient: 1.20x10 ^-13 [m ³ (STP) · m / (s · m ² · kPa) ]
PA-4) n-butyl acrylate / glycidyl methacrylate copolymer (70:30) Mw = 33000
Oxygen transmission coefficient: 1.25 x 10 ^-13 [m ³ (STP) · m / (s · m ² · kPa)]
PA-5) Copolymer of n-butyl acrylate / 4-hydroxyethyl acrylate glycidyl ether (70:30) Mw = 18200 Oxygen permeability coefficient: 1.72 × 10 ^-13 [m ³ (STP) · m / (s · m ²・ KPa)]
PA-6) Copolymer of n-butyl acrylate / phenoxyethyl acrylate acrylate (70:30) MW = 18500 Oxygen permeability: 1.47 × 10 ^-13 [m ³ (STP) · m / (s · m ² · kPa ]]
PA-7) Copolymer of n-butyl acrylate / t-butyl acrylamide (90:10) Mw = 30600 Oxygen transmission coefficient: 2.11 × 10 ^-13 [m ³ (STP) ・ m / (s ・ m ²・ kPa) ]
PA-8) Copolymer of n-butyl acrylate / N-isopropylacrylamide (90:10) Mw = 30300 Oxygen transmission coefficient: 2.15 × 10 ^-13 [m ³ (STP) · m / (s · m ² · kPa) ]
PA-9) Copolymer of methyl acrylate / M-90G (manufactured by Shin-Nakamura Chemical Co., Ltd.) (70:30) Mw = 2
5800 Oxygen transmission coefficient: 2.48 × 10 ^-13 [m ³ (STP) · m / (s · m ² · kPa)]
PA-10) n-Butyl Acrylate / N-Isopropyleneacrylamide Copolymer (70:30) Mw = 30600 Oxygen Permeation Coefficient: 0.09 × 10 ^-13 [m ³ (STP) ・ m / (s ・ m ²・ kPa) ]
PA-11) Copolymer of n-butyl acrylate / t-butyl acrylamide (50:50) MW = 25900 Oxygen transmission coefficient: 0.16 × 10 ^-13 [m ³ (STP) · m / (s · m ² · kPa) ]

  In the present invention, heat and radiation can be used for proceeding the polymerization of the monomer, and α rays, γ rays, X rays, ultraviolet rays, visible rays, electron rays and the like can be used as the radiation. Of these, ultraviolet rays and visible rays are preferably used from the viewpoint of cost and safety, and ultraviolet rays are more preferably used.

  When ultraviolet rays or visible rays are used as heat or radiation, a polymerization initiator or a sensitizer for initiating polymerization of the monomer is used in combination.

[Polymerization initiator]
Examples of the thermal polymerization initiator include azobis compounds, peroxides, hydroperoxides, redox catalysts, and the like, for example, inorganic peroxides such as potassium persulfate and ammonium persulfate, t-butyl peroctoate, benzoyl peroxide, isopropyl peroxide. Organic peroxides such as carbonate, 2,4-dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, dicumyl peroxide, 2,2'-azobisisobutyrate, 2,2'-azobisiso Butyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2,4,4-trimethylpentane) ), 2,2'-azobiscyanovaleric acid, 1,1'-azobi (1-acetoxy-1-phenylethane), 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] And hydrochloride, 2,2'-azobis {2-methyl-N- [1,1'-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, and the like.

  These initiators are preferably contained in the colored fine particles, that is, oil-soluble, and particularly preferably an azobis compound. Accordingly, examples of particularly preferred thermal polymerization initiators include 2,2′-azobisisobutyrate, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile). ), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2,4,4-trimethylpentane) and the like.

  In the present invention, the photopolymerization initiator is not particularly limited as long as radicals generated by light and other active species react with the polymerizable double bond in the monomer.

  As photopolymerization initiators, acetophenone derivatives, benzophenone derivatives, benzyl derivatives, benzoin derivatives, benzoin ether derivatives, benzyl dialkyl ketal derivatives, thioxanthone derivatives, acylphosphine oxide derivatives, metal complexes, p-dialkylaminobenzoic acids, azo compounds, peroxides Compounds are generally known, and acetophenone derivatives, benzyl derivatives, benzoin ether derivatives, benzyl dialkyl ketal derivatives, thioxanthone derivatives, and acyl phosphine oxide derivatives are preferred. Acetophenone derivatives, benzoin ether derivatives, benzyl dialkyl ketal derivatives, acyl phosphine Oxide derivatives are particularly preferred.

  Examples of photopolymerization initiators include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, benzophenone, p, p'-dichlorobenzophenone, p, p'-bisdiethylamino. Benzophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin isopropyl ether, benzoin-n-propyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, 1-hydroxy-cyclohexyl phenyl ketone, tetramethylthiuram monosulfide, thioxanthone, 2-chloro Thioxanthone, 2,4-dimethylthioxanthone, 2,2-dimethylpropioyl diphenylphosphine oxide, 2-methyl-2-ethyl Ruhexanoyl diphenylphosphine oxide, 2,6-dimethylbenzoyl diphenylphosphine oxide, 2,6-dimethoxybenzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2,3,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,3,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6- Trimethoxybenzoyl-diphenylphosphine oxide, 2,4,6-trichlorobenzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl naphthyl phosphonate Bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -finyl) titanium, p-dimethylaminobenzoic acid, p-diethylamino Examples include benzoic acid, azobisisobutyronitrile, 1,1′-azobis (1-acetoxy-1-phenylethane), benzoin peroxide, and di-tert-butyl peroxide.

  Furthermore, examples of the photopolymerization initiator include photopolymerization initiators described on pages 65 to 148 of “Ultraviolet curing system” written by Kiyosuke Kato (published by General Technology Center Co., Ltd .: 1989). Can do. These photopolymerization initiators can be used alone or in combination of two or more, and may be used in combination with a sensitizer.

  The amount of these photopolymerization initiators is not particularly limited, but is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, and more preferably 3 to 10% by mass with respect to the hydrophobic ethylenically unsaturated monomer. Is particularly preferred. If it is less than 0.5% by mass, it will not be cured or the curing time will be slow, and if it exceeds 20% by mass, the colored fine particle dispersion will be precipitated or separated over time, and the properties such as strength and rubbing resistance of the ink after curing will be exhibited. Since it may deteriorate, it is not preferable.

  The sensitizer is not activated by light irradiation alone, but when used together with the photopolymerization initiator, it is more effective than the photopolymerization initiator used alone, and amines are generally used. The addition of amines increases the curing rate, primarily because hydrogen is supplied to the photopolymerization initiator by the action of hydrogen abstraction, and secondly, the generated radicals are combined with oxygen molecules in the atmosphere and are reactive. This is because the amine has an action of trapping oxygen dissolved in the composition.

  Sensitizers include amine compounds (aliphatic amines, amines containing aromatic groups, piperidine, reaction products of epoxy resins and amines, triethanolamine triacrylate, etc.), urea compounds (allylthiourea, o-tolylthiourea, etc.) ), Sulfur compounds (sodium diethyldithiophosphate, soluble salts of aromatic sulfinic acid, etc.), nitrile compounds (N, N-diethyl-p-aminobenzonitrile, etc.), phosphorus compounds (tri-n-butylphosphine, sodium diethyl) Dithiophosphide, etc.), nitrogen compounds (Michler ketone, N-nitrisohydroxylamine derivative, oxazolidine compound, tetrahydro-1,3-oxazine compound, formaldehyde or a condensate of acetaldehyde and diamine), chlorine compound (carbon tetrachloride, Kisa chloroethane, etc.), and the like.

  The usage-amount of a sensitizer is 0.1-10 mass% normally, 0.2-5 mass% is preferable, and 0.2-2 mass% is especially preferable. The selection, combination, and blending ratio of the photoinitiator and sensitizer may be appropriately selected depending on the hydrophobic ethylenically unsaturated monomer used and the apparatus used.

  As a light source for irradiating ultraviolet rays or visible light, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a carbon arc lamp, a xenon lamp, a chemical lamp, or the like can be used.

[Oil-soluble compounds]
The oil-soluble compounds used in the present invention include all water-insoluble compounds and are not particularly limited, and can be appropriately selected from known compounds according to the purpose within a range not impairing the effects of the invention. Examples of such compounds include oil-soluble dyes, electron-donating colorless dyes, organic EL materials, ultraviolet absorbers, antioxidants, anti-fading agents, liquid crystal compounds, fluorescent compounds, and polymers thereof. Can be mentioned.
The oil-soluble compound used in the present invention means a compound that is substantially insoluble in water. More specifically, the solubility in water at 25 ° C. (the mass of the dye that can be dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Among these, examples of the oil-soluble compound used in the present invention include so-called water-insoluble pigments and oil-soluble dyes, and oil-soluble dyes (oil-soluble dyes) are particularly preferable.

The oil-soluble dye preferably has a melting point of 200 ° C. or lower, more preferably 150 ° C. or lower, and particularly preferably 100 ° C. or lower. By using the oil-soluble dye having a low melting point, the precipitation of pigment crystals in the fine particle dispersion and the ink is suppressed, and the storage stability of the ink is improved.
In the ink of the present invention, one kind of oil-soluble dye may be used alone, or several kinds may be mixed and used. Furthermore, other water-soluble dyes, disperse dyes, pigments, and other colorants may be contained as necessary within the range not impairing the effects of the present invention.

  As the oil-soluble dye, conventionally known dye compounds can be used. Specific examples include dyes described in paragraphs [0023] to [0053] of JP-A No. 2002-114930.

  As the oil-soluble dye used in the present invention, a dye having a high oxidation potential (noble) is desirable in order to improve fading, particularly resistance to an oxidizing substance such as ozone and curing properties. It is desirable that the voltage be higher than 0.0 V (vs SCE). This oxidation potential is preferably higher, more preferably the oxidation potential is higher than 1.1 V (vs SCE), and more preferably noble than 1.15 V (vs SCE). Regarding this oxidation potential, for example, paragraphs [0049] to [0051] of JP-A-2002-309118 are described in detail.

  A preferable structure for the yellow dye used in the present invention is an oil-soluble dye represented by the following general formula (Y-I). Here, the oil-soluble dye of the general formula (Y-I) may be used not only for yellow but also for inks of any color such as black ink, green ink, and red ink.

Formula (Y-I) A-N = NB

  In the above general formula (Y-I), A and B each independently represents an optionally substituted heterocyclic group. Such a heterocyclic ring is preferably a 5- or 6-membered heterocyclic ring, which may be a monocyclic structure or a polycyclic structure in which two or more rings are fused, It may be an aromatic heterocycle or a non-aromatic heterocycle. As a hetero atom constituting the heterocyclic ring, a nitrogen atom, an oxygen atom, or a sulfur atom is preferable.

  Examples of the heterocyclic ring represented by A include 5-pyrazolone, pyrazole, oxazolone, isoxazolone, barbituric acid, pyridone, rhodanine, pyrazolidinedione, pyrazolopyridone, meldrum acid, and further hydrocarbon aromatics. A condensed heterocyclic ring in which a ring or a heterocyclic ring is condensed is preferable. Among these, 5-pyrazolone, 5-aminopyrazole, pyridone, and pyrazoloazoles are particularly preferable, and 5-aminopyrazole, 2-hydroxy-6-pyridone, and pyrazolotriazole are preferable.

  The heterocyclic ring represented by B includes pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, cinnoline, phthalazine, quinoxaline, pyrrole, indole, furan, benzofuran, thiophene, benzothiophene, pyrazole, imidazole, benzo Preferable examples include imidazole, triazole, oxazole, isoxazole, benzoxazole, thiazole, benzothiazole, isothiazole, benzoisothiazole, thiadiazole, benzisoxazole, pyrrolidine, piperidine, piperazine, imidazolidine and thiazoline. Among them, pyridine, quinoline, thiophene, benzothiophene, pyrazole, imidazole, benzimidazole, triazole, oxazole, isoxazole, benzoxazole, thiazole, benzothiazole, isothiazole, benzoisothiazole, thiadiazole, and benzoisoxazole are preferable. Thiophene, pyrazole, thiazole, benzoxazole, benzisoxazole, isothiazole, imidazole, benzothiazole, thiadiazole are more preferable, and in particular, pyrazole, benzothiazole, benzoxazole, imidazole, 1,2,4-thiadiazole, 1,3 1,4-thiadiazole is preferred.

  Examples of the substituents substituted on A and B include halogen atoms, alkyl groups, cycloalkyl groups, aralkyl groups, alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups, cyano groups, hydroxyl groups, nitro groups, alkoxy groups, Aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy, amino group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group Sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, alkyl and arylsulfinyl group, alkyl and aryl Ruhoniru group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an imido group, a phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, and a silyl group.

  Among the dyes represented by the general formula (Y-I), dyes represented by the following general formulas (Y-II), (Y-III), and (Y-IV) are more preferable.

In the general formula (Y-II), R ¹ and R ³ are each independently a hydrogen atom, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, an alkoxy group, an alkylthio group, an arylthio group, an aryl group, or an ion. Represents a hydrophilic hydrophilic group. R ² represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, a carbamoyl group, an acyl group, an aryl group or a heterocyclic group. R4 represents a heterocyclic group.

In the general formula (Y-III), R ⁵ represents a hydrogen atom, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, an alkoxy group, an alkylthio group, an arylthio group, an aryl group, or an ionic hydrophilic group. . Za is, -N =, - NH-, or C (R ¹¹⁾ = represents, Zb and Zc each independently, -N =, or C (R ¹¹⁾ = represents, wherein said R ¹¹ is Represents a hydrogen atom or a nonmetallic substituent. R6 represents a heterocyclic group.

In the general formula (Y-IV), R ⁷ and R ⁹ are each independently a hydrogen atom, cyano group, alkyl group, cycloalkyl group, aralkyl group, aryl group, alkylthio group, arylthio group, alkoxycarbonyl group, A carbamoyl group or an ionic hydrophilic group is represented. R ⁸ is a hydrogen atom, halogen atom, alkyl group, alkoxy group, aryl group, aryloxy group, cyano group, acylamino group, sulfonylamino group, alkoxycarbonylamino group, ureido group, alkylthio group, arylthio group, alkoxycarbonyl group, It represents a carbamoyl group, a sulfamoyl group, a sulfonyl group, an acyl group, an amino group, a substituted amino group, a hydroxy group, or an ionic hydrophilic group. R ¹⁰ represents a heterocyclic group.

The substituents represented by R ^{1 to} R ³ , R ⁵ , R ⁷ , R ⁸ and R ^{9 in the} general formulas (Y-II), (Y-III), and (Y-IV) will be described in detail below.

The alkyl group represented by R ^{1 to} R ³ , R ⁵ , R ⁷ , R ⁸ and R ⁹ includes an alkyl group having a substituent and an unsubstituted alkyl group. The alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, and examples of the substituent include a hydroxyl group, an alkoxy group, a cyano group, a halogen atom, and an ionic hydrophilic group.
Specific examples of the alkyl group include methyl, ethyl, butyl, isopropyl, t-butyl, hydroxyethyl, methoxyethyl, cyanoethyl, trifluoromethyl, 3-sulfopropyl, and 4-sulfobutyl.

The cycloalkyl group represented by R ^{1 to} R ³ , R ⁵ , R ⁷ and R ⁹ includes a cycloalkyl group having a substituent and an unsubstituted cycloalkyl group. The cycloalkyl group is preferably a cycloalkyl group having 5 to 12 carbon atoms, and examples of the substituent include ionic hydrophilic groups.
Specific examples of the cycloalkyl group include cyclohexyl.

The aralkyl group represented by R ^{1 to} R ³ , R ⁵ , R ⁷ and R ⁹ includes an aralkyl group having a substituent and an unsubstituted aralkyl group. The aralkyl group is preferably an aralkyl group having 7 to 20 carbon atoms, and examples of the substituent include an ionic hydrophilic group.
Specific examples of the aralkyl group include benzyl and 2-phenethyl.

The aryl group represented by R ^{1 to} R ³ , R ⁵ , R ⁷ and the like includes an aryl group having a substituent and an unsubstituted aryl group. The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, an alkylamino group, and an ionic hydrophilic group.
Specific examples of the aryl group include phenyl, p-tolyl, p-methoxyphenyl, o-chlorophenyl, and m- (3-sulfopropylamino) phenyl.

The alkylthio group represented by R ¹ , R ³ , R ⁵ , R ⁷ , R ⁸ and R ⁹ includes an alkylthio group having a substituent and an unsubstituted alkylthio group. As said alkylthio group, a C1-C20 alkylthio group is preferable, and an ionic hydrophilic group is mentioned as an example of the said substituent.
Preferable examples of the alkylthio group include a methylthio group and an ethylthio group.

The arylthio group represented by R ¹ , R ³ , R ⁵ , R ⁷ , R ⁸ and R ⁹ includes an arylthio group having a substituent and an unsubstituted arylthio group. The arylthio group is preferably an arylthio group having 6 to 20 carbon atoms, and examples of the substituent include an alkyl group and an ionic hydrophilic group.
Specific examples of the arylthio group include a phenylthio group and p-tolylthio.

The heterocyclic group represented by R ² is preferably a 5-membered or 6-membered heterocyclic ring, which may be further condensed. As a hetero atom constituting the heterocyclic ring, a nitrogen atom, a sulfur atom and an oxygen atom are preferable. Further, it may be an aromatic heterocyclic ring or a non-aromatic heterocyclic ring. The heterocyclic ring may be further substituted, and examples of the substituent include the same substituents as those described later for the aryl group. Preferred heterocycles include 6-membered nitrogen-containing aromatic heterocycles, among which triazine, pyrimidine and phthalazine are particularly preferred.

Preferred examples of the halogen atom represented by R ⁸ include a fluorine atom, a chlorine atom, and a bromine atom.
The alkoxy group represented by R ¹ , R ³ , R ⁵ and R ⁸ includes an alkoxy group having a substituent and an unsubstituted alkoxy group. The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, and examples of the substituent include a hydroxyl group and an ionic hydrophilic group.
Specific examples of the alkoxy group include methoxy, ethoxy, isopropoxy, methoxyethoxy, hydroxyethoxy, and 3-carboxypropoxy.

The aryloxy group represented by R ⁸ includes an aryloxy group having a substituent and an unsubstituted aryloxy group. The aryloxy group is preferably an aryloxy group having 6 to 20 carbon atoms, and examples of the substituent include an alkoxy group and an ionic hydrophilic group.
Specific examples of the aryloxy group include phenoxy, p-methoxyphenoxy and o-methoxyphenoxy.
The acylamino group represented by R8 includes an acylamino group having a substituent and an unsubstituted acylamino group. The acylamino group is preferably an acylamino group having 2 to 20 carbon atoms, and examples of the substituent include an ionic hydrophilic group.
Specific examples of the acylamino group include acetamide, propionamide, benzamide and 3,5-disulfobenzamide.

The sulfonylamino group represented by R ⁸ includes a sulfonylamino group having a substituent and an unsubstituted sulfonylamino group.
The sulfonylamino group is preferably a sulfonylamino group having 1 to 20 carbon atoms, and examples of the substituent include a methyl group, an ethyl group, an iso-propyl group, and an n-butyl group. Iso-butyl group and tert-butyl group are included.
Suitable examples of the sulfonylamino group include methylsulfonylamino and ethylsulfonylamino.

The alkoxycarbonylamino group represented by R ⁸ includes an alkoxycarbonylamino group having a substituent and an unsubstituted alkoxycarbonylamino group. The alkoxycarbonylamino group is preferably an alkoxycarbonylamino group having 2 to 20 carbon atoms, and examples of the substituent include an ionic hydrophilic group.
Specific examples of the alkoxycarbonylamino group include ethoxycarbonylamino.

The ureido group represented by R ⁸ includes a ureido group having a substituent and an unsubstituted ureido group. The ureido group is preferably a ureido group having 1 to 20 carbon atoms, and examples of the substituent include an alkyl group and an aryl group.
Specific examples of the ureido group include 3-methylureido, 3,3-dimethylureido and 3-phenylureido.

The alkoxycarbonyl group represented by R ⁷ , R ⁸ and R ⁹ includes an alkoxycarbonyl group having a substituent and an unsubstituted alkoxycarbonyl group. The alkoxycarbonyl group is preferably an alkoxycarbonyl group having 2 to 20 carbon atoms, and examples of the substituent include an ionic hydrophilic group.
Specific examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl.

The carbamoyl group represented by R ² , R ⁷ , R ⁸ and R ⁹ includes a carbamoyl group having a substituent and an unsubstituted carbamoyl group. Examples of the substituent include an alkyl group.
Specific examples of the rurubamoyl group include a methylcarbamoyl group and a dimethylcarbamoyl group.
The sulfamoyl group represented by R ⁸ includes a sulfamoyl group having a substituent and an unsubstituted sulfamoyl group. Examples of the substituent include an alkyl group.
Specific examples of the sulfamoyl group include a dimethylsulfamoyl group and a di- (2-hydroxyethyl) sulfamoyl group.

Preferable examples of the sulfonyl group represented by R ⁸ include methanesulfonyl and phenylsulfonyl.
The acyl group represented by R ² and R ⁸ includes an acyl group having a substituent and an unsubstituted acyl group. The acyl group is preferably an acyl group having 1 to 20 carbon atoms, and examples of the substituent include an ionic hydrophilic group.
Preferable examples of the acyl group include acetyl and benzoyl.

The ionic hydrophilic groups represented by R ¹ , R ³ , R ⁵ , R ⁷ , R ⁸ and R ⁹ include a carboxyl group, a quaternary ammonium salt, a sulfonic acid group, and the like. An acid group is a suitable example.

The aralkyl group represented by R ² includes an aralkyl group having a substituent and an unsubstituted aralkyl group. Examples of the substituent include a hydroxy group, an alkoxy group, a cyano group, a halogen atom, and ionic hydrophilicity. A group is included. Examples of the aryl moiety of the aralkyl group include a phenyl group and a naphthyl group, and specific examples include a benzyl group and a 2-phenethyl group.

In the substituted amino group represented by R ⁸ , examples of the substituent include an alkyl group, an aryl group, and a heterocyclic group.
Specific examples of the substituted amino group include methylamino, diethylamino, anilino and 2-chloroanilino.

The heterocyclic group represented by R ⁴ , R ⁶ , and R ¹⁰ is the same as the optionally substituted heterocyclic group represented by B in the general formula (YI), and is preferably a preferable example. The same applies to examples and particularly preferred examples.
Examples of the substituent include an ionic hydrophilic group, an alkyl group having 1 to 12 carbon atoms, an aryl group, an alkyl or arylthio group, a halogen atom, a cyano group, a sulfamoyl group, a sulfonamino group, a carbamoyl group, and an acylamino group. The above alkyl group and aryl group may further have a substituent.

In the general formula (Y-III), Za represents —N═, —NH—, or C (R ¹¹ ) ═. Zb and Zc each independently represent -N = or C (R ¹¹⁾ =. Here, R ¹¹ represents a hydrogen atom or a nonmetallic substituent. As the nonmetallic substituent represented by R ¹¹ , a cyano group, a cycloalkyl group, an aralkyl group, an aryl group, an alkylthio group, an arylthio group, or an ionic hydrophilic group is preferable. Each of the above substituents has the same meaning as each of the substituents represented by R ¹ , and preferred examples thereof are also the same. Examples of the skeleton of a heterocyclic ring composed of two 5-membered rings included in the general formula (Y-III) are shown below.

  Examples of the substituent in the case where each substituent described above may further have a substituent include substituents that may be substituted on the heterocyclic rings A and B of the general formula (Y-I). Can be mentioned.

  Specific examples (Y-101 to Y-160) of the dye represented by the general formula (Y-I) are shown below, but the present invention is not limited to these specific examples. These compounds can be synthesized with reference to, for example, JP-A-2-24191 and JP-A-2001-279145.

Preferred structures of the magenta dye used in the present invention include general formulas (3) and (4) of JP-A No. 2002-114930. Specific examples thereof include paragraphs [0054] to [2002] of JP-A No. 2002-114930. The compound of [0073] is mentioned.
Particularly preferred structures include azo dyes represented by general formulas (M-1) to (M-2) described in paragraph numbers [0084] to [0122] of JP-A No. 2002-121414, Specific examples thereof include compounds of paragraph numbers [0123] to [0132] of JP-A No. 2002-121414. The oil-soluble dyes represented by the general formulas (3), (4) and (M-1) to (M-2) may be used not only for magenta but also for any color ink such as black ink and red ink. .

Preferred structures of the cyan dye used in the present invention include dyes represented by formulas (I) to (IV) in JP-A No. 2001-181547, and paragraphs [0063] to [0078] in JP-A No. 2002-121414. Examples of the dyes represented by the general formulas (IV-1) to (IV-4) described are listed in the paragraph numbers [0052] to [0066] of JP-A No. 2001-181547. Examples thereof include compounds of paragraph numbers [0079] to [0081] of Kai 2002-121414.
Particularly preferred structures include phthalocyanine dyes represented by general formulas (CI) and (C-II) described in paragraph numbers [0133] to [0196] of JP-A No. 2002-121414, Furthermore, the phthalocyanine dye represented by general formula (C-II) is mentioned preferably. Specific examples thereof include compounds of paragraph numbers [0198] to [0201] of JP-A No. 2002-121414. The oil-soluble dyes of the above formulas (I) to (IV), (IV-1) to (IV-4), (CI) and (C-II) are not only cyan but also black ink or green ink. The ink may be used for any color ink.

  In the present invention, the content of the oil-soluble dye in the ink is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, and particularly preferably 0.2 to 6% by mass.

[Other ingredients]
In the ink composition of the present invention, in addition to the hydrophobic ethylenically unsaturated monomer, the oil-soluble dye and the polymerization initiator, a high boiling point is used for the purpose of adjusting the viscosity and polarity of the composition itself and adjusting the polymerization activity. These hydrophobic organic solvents and polymers can be included as appropriate.

  The high boiling organic solvent is an organic solvent having a boiling point higher than 100 ° C. The high-boiling organic solvent preferably has a boiling point of 150 ° C. or higher, more preferably 170 ° C. or higher. Examples include polyhydric alcohols, esters of aliphatic carboxylic acids, phosphoric esters, hydrocarbons, and the like. Specific examples include diethylene glycol, trimethylolpropane, dibutyl phthalate, and 2-ethylhexyl benzoate. And alkylnaphthalene. More specific specific examples include hydrophobic high boiling point organic solvents described in Japanese Patent Application No. 2000-78518. These can be either liquid or solid at room temperature depending on the purpose. The solvent may be used alone or in combination. The amount used is preferably 0 to 20% by mass, more preferably 0 to 10% by mass.

  The polymer can be used for adjusting the polarity and viscosity of the colored fine particles, improving the solubility of the oil-soluble dye, adjusting the adhesion of the cured ink to the recording material, and adjusting the light resistance. The polymer preferably has high compatibility with dyes and monomers, and the molecular weight is preferably 50000 or less, and more preferably 20000 or less. Examples of the polymer include, for example, vinyl polymer, polyurethane, polyester and the like. Specifically, polybutyl acrylate, poly (isobutyl methacrylate-hydroxyethyl acrylate) (copolymerization mass ratio 95: 5), poly (isopropyl acrylate) -Tetrahydrofurfuryl acrylate) (copolymerization mass ratio 70:30), poly (butyl methacrylate-N-methoxymethylacrylamide) (copolymerization mass ratio 80:20), polybutyl acrylate-polydimethylsiloxane block copolymer (copolymer) Polymerization mass ratio 90:10) and the like. The polymers may be used alone or in combination. The amount of the polymer used varies depending on the type and amount of the ethylenically unsaturated monomer or oil-soluble dye, but is preferably 0 to 40% by mass, particularly preferably 0 to 20% by mass.

  In the present invention, a storage stabilizer can be included. Storage stabilizers suppress undesirable polymerization during storage, and examples include quaternary ammonium salts, hydroxyamines, cyclic amides, nitriles, substituted ureas, heterocyclic compounds, organic acids, hydroquinone, Examples include hydroquinone monoethers, organic phosphines, copper compounds, and specifically benzyltrimethylammonium chloride, diethylhydroxylamine, benzothiazole, 4-amino-2,2,6,6-tetramethylpiperidine, citric acid , Hydroquinone monobutyl ether, copper naphthenate and the like. The amount used is preferably 0.005 to 1% by weight, more preferably 0.01 to 0.5% by weight, particularly preferably 0.01 to 0.2% by weight, based on the polymerizable ethylenically unsaturated monomer. .

[Production of ink composition]
The ink composition of the present invention includes a non-aqueous (oil-based) ink composition that includes at least the hydrophobic ethylenically unsaturated monomer, and is preferably produced by stirring and mixing an oil-soluble compound, a polymerization initiator, and the like. .
There is also an ink composition obtained by dispersing these oil components in an aqueous medium.
Examples of the method for producing the latter ink composition include a method of emulsifying and dispersing the hydrophobic ethylenically unsaturated monomer. As this emulsification dispersion method, there is a method of emulsifying the monomer into fine particles by either adding water to the organic solvent phase containing the monomer or adding the organic solvent phase to water. Preferably mentioned.

  As the emulsifying and dispersing apparatus used in the emulsifying and dispersing method, a known apparatus such as a simple stirrer or impeller stirring method, an in-line stirring method, a mill method such as a colloid mill, or an ultrasonic method can be used. A high-pressure emulsifying and dispersing apparatus is preferable, and among them, a high-pressure homogenizer is particularly preferable.

  As for the high-pressure homogenizer, detailed mechanisms are described in US Pat. No. 4,533,254, JP-A-6-47264, etc., but as a commercially available apparatus, a Gorin homogenizer (APV GAULIN INC.), A microfluidizer, etc. (MICROFLUIDEX INC.), Optimizer (Sugino Machine Co., Ltd.) and the like.

  In addition, a high-pressure homogenizer equipped with a mechanism for atomizing in an ultrahigh-pressure jet stream as described in US Pat. No. 5,720,551 in recent years is particularly effective for emulsification dispersion of the present invention. DeBEE2000 (BEE INTERNATIONAL LTD.) Is an example of an emulsifying and dispersing apparatus using this ultra-high pressure jet stream.

  The pressure when emulsifying and dispersing using the high-pressure emulsifying dispersion device is preferably 50 MPa or more (500 bar or more), more preferably 60 MPa or more (600 bar or more), and further preferably 180 MPa or more (1800 bar or more). In the present invention, at the time of the emulsification dispersion, for example, it is particularly preferable to use two or more types of emulsifiers together by a method such as emulsification with a stirring emulsifier and then passing through a high-pressure homogenizer. It is also preferable to once emulsify and disperse with these emulsifiers, add additives such as wetting agents and surfactants, and then pass through the high-pressure homogenizer again while filling the ink composition into the cartridge.

  In the emulsification dispersion, when a low boiling point organic solvent is contained in addition to the monomer, it is preferable to substantially remove the low boiling point solvent from the viewpoint of stability and safety and health of the emulsion. As a method for substantially removing the low-boiling organic solvent, various known methods such as an evaporation method, a vacuum evaporation method, and an ultrafiltration method can be employed depending on the type of the low-boiling organic solvent. . The step of removing the low-boiling organic solvent is preferably performed as soon as possible immediately after emulsification.

  Various surfactants can be used in the emulsification dispersion. For example, fatty acid salt, alkyl sulfate ester salt, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, alkyl phosphate ester salt, naphthalene sulfonate formalin condensate, polyoxyethylene alkyl sulfate ester salt, etc. Surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethyleneoxypropylene block Nonionic surfactants such as copolymers, and SURFYNOLS (Air) which is an acetylene-based polyoxyethylene oxide surfactant products & Chemicals), amine oxide type amphoteric surfactants such as N, N-dimethyl-N-alkylamine oxide, and further, pages (37) to (38) of JP-A-59-157636. Research Disclosure No. Preferred are those described in 308119 (1989).

  When emulsifying and dispersing fine particles containing the monomer in an aqueous medium to form an aqueous ink, it is particularly important to control the particle size. In order to increase color purity and density when an image is formed by inkjet, it is preferable to reduce the average particle diameter of the fine particles. Specifically, the volume average particle diameter of the fine particles is preferably 1 nm or more and 300 nm or less, more preferably 2 nm or more and 200 nm or less, and further preferably 2 nm or more and 100 nm or less. Further, if the fine particles have coarse particles, the printing performance may be deteriorated. For example, when the coarse particles clog the nozzles of the head, or even if they are not clogged, the ink may not be ejected or the ejection may be misaligned. Therefore, it is preferable that the presence ratio of coarse particles is low, and when an ink is prepared, it is preferable to have 10 or less particles of 5 μm or more in 1 μl of ink and 1000 or less particles of 1 μm or more. As a method for removing these coarse particles, a known centrifugal separation method, microfiltration method or the like can be used. These separation means may be performed immediately after the emulsification dispersion, or may be performed immediately before filling the ink cartridge after various additives such as a wetting agent and a surfactant are added to the emulsification dispersion. In order to reduce the average particle diameter of the colored fine particles and reduce the coarse particles, it is effective to use a mechanical emulsifier.

  In the ink composition of the present invention, the content of the monomer is not particularly limited, but the content of the monomer of the present invention in the colored fine particles is 25% by mass or more from the viewpoint of good ink penetration into recording paper. It is preferably 90% by mass or less, and more preferably 50% by mass or more and 85% by mass or less. In addition, from the viewpoint of maintaining good solubility of the oil-soluble compound, the monomer of the present invention is preferably used in an amount of 30% by mass to 2000% by mass, and 100% by mass to 1500% by mass with respect to the oil-soluble compound. It is more preferable that On the other hand, if the amount of the monomer used is too large, the proportion of the oil phase is too large, which tends to make stable and fine dispersion difficult. From this viewpoint, the amount of the monomer used is preferably 50 to 1500% by mass, more preferably 100 to 1000% by mass, based on the oil-soluble dye.

  As a preferred embodiment of the present invention, when the monomer contains the polymerization initiator, the method for producing the ink composition includes a liquid containing at least an oil-soluble compound, the hydrophobic ethylenically unsaturated monomer, and a polymerization initiator. It can be carried out by emulsifying and dispersing in the same manner as described above. However, when the polymerization initiator is a thermal polymerization initiator, the temperature at the time of emulsification dispersion or desolvation of the low boiling point organic solvent needs to be low, and the temperature is preferably 40 ° C. or less, particularly Preferably it is 30 degrees C or less. The polymerization initiator may be directly added to the ink composition obtained by emulsification and dispersion.

  The ink composition of the present invention, particularly a water-based ink composition, may further contain other components appropriately selected as necessary.

  The other components are contained within a range that does not impair the effects of the present invention. For example, drying inhibitors, penetration enhancers, ultraviolet absorbers, antioxidants, antifungal agents, pH adjusters, surface tension adjusters, Well-known additives, such as an antifoamer, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust inhibitor, a chelating agent, are mentioned.

  The anti-drying agent is preferably used for the purpose of preventing clogging due to dry operation of the ink composition at the ink ejection port of the nozzle used in the ink jet recording method.

  The anti-drying agent is preferably a water-soluble organic solvent having a vapor pressure lower than that of water. Specific examples of the drying inhibitor include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, and acetylene. Polyhydric alcohols typified by glycol derivatives, glycerin, trimethylolpropane, etc., polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether Lower alkyl ethers, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, heterocyclic rings such as N-ethylmorpholine, sulfolane, dimethylsulfone Kishido, sulfur-containing compounds such as 3-sulfolene, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Among these, polyhydric alcohols such as glycerin and diethylene glycol are more preferable. Moreover, these may be used individually by 1 type and may use 2 or more types together. These drying inhibitors are preferably contained in the ink composition in an amount of 10 to 50% by mass.

The penetration accelerator is preferably used for the purpose of allowing the ink composition to penetrate better into paper.
Examples of the penetration enhancer include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, and a nonionic surfactant. Can be mentioned. The penetration enhancer is contained within a range that does not cause printing bleeding, paper loss (print through), and the like, and usually exhibits a sufficient effect if it is contained in the ink composition by about 5 to 30% by mass.

  The ultraviolet absorber is used for the purpose of improving the storability of images. For example, JP-A Nos. 58-185677, 61-190537, JP-A-2-782, and JP-A-5-97075. Benzotriazole compounds described in JP-A-9-34057, etc., benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194443, US Pat. No. 3,214,463, etc. 48-30492, 56-21114, and cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, and 8-239368. And triazine compounds described in JP-A-10-182621, JP-A-8-501291, etc. Jar No. Examples thereof include compounds described in No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays, such as stilbene and benzoxazole compounds, so-called fluorescent brighteners, and the like.

  The antioxidant is used for the purpose of improving image storability. For example, various organic and metal complex antifading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, and the like. Examples of the metal complex-based antifading agent include nickel complexes and zinc complexes. No. 17643, No. VII, I to J, ibid. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .

  Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof. These are preferably used in the ink in an amount of 0.02 to 1.00% by mass.

  Suitable examples of the surface tension adjusting agent include nonionic, cationic, and anionic surfactants. The surface tension of the ink composition of the present invention is preferably 25 to 70 mN / m, and more preferably 25 to 60 mN / m.

  The viscosity of the ink composition of the present invention is preferably 30 mPa · s or less, and more preferably 10 mPa · s or less.

  As the antifoaming agent, fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can be used as necessary.

  The pH adjusting agent can be suitably used in terms of adjusting the pH of the colored fine particle dispersion and imparting dispersion stability, and is preferably added so as to have a pH of 4.5 to 10.0. It is more preferable to add so that it may become 0.0. The pH adjuster is preferably an organic base or inorganic alkali as a basic one, and an organic acid or inorganic acid or the like as an acidic one. In the basic pH adjuster, among the organic bases, triethanolamine, diethanolamine, N-methyldiethanolamine, dimethylethanolamine and the like are more preferable. Among the inorganic alkalis, alkali metal hydroxides, carbonates, Ammonia and the like are more preferable. Among the alkali metal hydroxides, sodium hydroxide, lithium hydroxide, potassium hydroxide, and the like are particularly preferable. Among the carbonates, sodium carbonate, sodium bicarbonate, and the like are particularly preferable. In the acidic pH adjuster, acetic acid, propionic acid, trifluoroacetic acid, alkylsulfonic acid and the like are more preferable among the organic acids, and hydrochloric acid, sulfuric acid, phosphoric acid and the like are more preferable among the inorganic acids.

[Image forming method]
The image forming method of the present invention is characterized by having a step of recording an image of the ink composition of the present invention on a recording material by an ink jet recording method and then a step of polymerizing a hydrophobic ethylenically unsaturated monomer.
Here, it is preferable to use an ink jet recording method using an ink jet printer. In the ink jet recording method, recording is performed on a recording material using the ink composition, but there are no particular restrictions on the ink nozzles used at that time, and they can be appropriately selected according to the purpose. The method for polymerizing the hydrophobic ethylenically unsaturated monomer is as described above.

<Recording material>
The recording material is not particularly limited, and examples thereof include known recording materials such as plain paper, resin-coated paper, ink jet paper, film, electrophotographic co-paper, fabric, glass, metal, ceramics, and the like. Among the recording materials, ink jet dedicated paper is preferable. For example, JP-A-8-169172, JP-A-8-27693, JP-A-2-276670, JP-A-7-276789, and JP-A-9-323475. JP-A-62-238783, JP-A-10-153898, JP-A-10-217473, JP-A-10-235995, JP-A-10-337947, JP-A-10-217597, JP-A-10-337947. What is described in the gazette, etc. is more preferable.

  In the present invention, among the recording materials, the following recording paper and recording film are particularly preferable. The recording paper and the recording film are formed by laminating a support and an ink receiving layer, and by laminating other layers such as a backcoat layer as necessary. Each layer including the ink receiving layer may be a single layer or two or more layers.

  The support is composed of chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP, and waste paper pulp such as DIP. , Binders, sizing agents, fixing agents, cationic agents, paper strength enhancers, etc., which are added and mixed, and manufactured with various devices such as long net paper machines and circular net paper machines can be used. In addition, synthetic paper, plastic film sheets, and the like may be used.

The thickness of the support is about 10 to 250 μm, and the basis weight is preferably 10 to 250 g / m ² .

  The support may be provided with the ink receptive layer, may further be provided with the back coat layer, and may be provided with a size press or anchor coat layer made of starch, polyvinyl alcohol or the like, and then the ink receptive layer. A layer and the back coat layer may be provided. The support may be flattened by a calendar device such as a machine calendar, a TG calendar, or a soft calendar.

  Among the above-mentioned supports, papers laminated on both sides with polyolefin (for example, polyethylene, polystyrene, polyethylene terephthalate, polybutene, and copolymers thereof) and plastic films are preferably used. It is more preferable to add a white pigment (for example, titanium oxide, zinc oxide, etc.) or a tinting dye (for example, cobalt blue, ultramarine blue, neodymium oxide, etc.) to the polyolefin.

  The ink receiving layer contains a pigment, an aqueous binder, a mordant, a water resistance agent, a light resistance improver, a surfactant, and other additives.

  The pigment is preferably a white pigment, and examples of the white pigment include calcium carbonate, kaolin, talc, clay, diatomaceous earth, synthetic amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, alumina, Preferable examples include inorganic white pigments such as lithopone, zeolite, barium sulfate, calcium sulfate, titanium dioxide, zinc sulfide and zinc carbonate, and organic pigments such as styrene pigment, acrylic pigment, urea resin and melamine resin. Among these white pigments, porous inorganic pigments are preferable, and synthetic amorphous silica having a large pore area is more preferable. As the synthetic amorphous silica, both anhydrous silicic acid obtained by a dry production method and hydrous silicic acid obtained by a wet production method can be used, but it is particularly preferable to use hydrous silicic acid.

  Examples of the aqueous binder include water-soluble polymers such as polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyalkylene oxide, and polyalkylene oxide derivatives. And water dispersible polymers such as styrene butadiene latex and acrylic emulsion. These aqueous binders may be used alone or in combination of two or more. Among these, polyvinyl alcohol and silanol-modified polyvinyl alcohol are preferable in terms of adhesion to the pigment and peel resistance of the ink receiving layer.

  The mordant is preferably immobilized. For that purpose, a polymer mordant is preferably used. Examples of the polymer mordant include JP-A Nos. 48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, 60-23835, 60-23852, 60-23835, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122942, 60 -235134, JP-A-1-161236, U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,273,853, 4,282,305 Are described in each specification of US Pat. No. 4,450,224. A polymer mordant described on pages 212 to 215 of JP-A-1-161236 is particularly preferred. When the polymer mordant described in the publication is used, an image with excellent image quality is obtained and the light resistance of the image is improved.

  The water-proofing agent is effective for making the image water-resistant, and a cationic resin is preferable. Examples of the cationic resin include polyamide polyamine epichlorohydrin, polyethyleneimine, polyamine sulfone, dimethyldiallylammonium chloride polymer, cationic polyacrylamide, colloidal silica, and the like. Among these, polyamide polyamine epichlorohydrin is particularly preferable. The content of the cationic resin is preferably 1 to 15% by mass, and more preferably 3 to 10% by mass with respect to the total solid content of the ink receiving layer.

  Examples of the light resistance improver include zinc sulfate, zinc oxide, hindered amine antioxidants, benzophenone and benzotriazole ultraviolet absorbers, and among these, zinc sulfate is particularly preferable.

  The surfactant functions as a coating aid, a peelability improver, a slippage improver or an antistatic agent. Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compound include a fluorine surfactant, an oily fluorine compound (for example, fluorine oil) and a solid fluorine compound resin (for example, tetrafluoroethylene resin). The organic fluoro compounds are described in JP-B-57-9053 (columns 8 to 17), JP-A-61-2994, and JP-A-62-135826.

  Examples of the other additives include pigment dispersants, thickeners, antifoaming agents, dyes, fluorescent whitening agents, preservatives, pH adjusting agents, matting agents, and hardening agents.

  The back coat layer contains a white pigment, an aqueous binder, and other components.

  Examples of the white pigment include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate. , Magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigments, styrenic plastic pigment, acrylic Organic pigments such as plastic pigments, polyethylene, microcapsules, urea resins, melamine resins, and the like.

  Examples of the aqueous binder include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, hydroxyethylcellulose, and polyvinylpyrrolidone. And water-dispersible polymers such as styrene butadiene latex and acrylic emulsion.

  Examples of the other components include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

  A polymer latex may be added to the constituent layers (including the backcoat layer) in the recording paper and recording film. The polymer latex is used for the purpose of improving film physical properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer latex is described in JP-A Nos. 62-245258, 62-136648, and 62-110066. When a polymer latex having a low glass transition temperature (40 ° C. or lower) is added to the layer containing the mordant, cracking and curling of the layer can be prevented. Further, curling can be prevented by adding a polymer latex having a high glass transition temperature to the back coat layer.

  In the image forming method of the present invention, the recording material to be used is not particularly limited, but it is formed by using a recording material in which an ink receiving layer is laminated on a support and the ink receiving layer contains a white pigment. This is preferable because the image has high image quality. In addition, in many conventional dispersed inks, when a recording material having an ink receiving layer containing a porous inorganic pigment such as a white pigment is used, the permeation into the recording material is poor, and the formed image is not easily processed. There was a problem that the dye peeled off from the surface when rubbed with. However, in the ink of the present invention, such a problem has been solved because a colored dispersion comprising an ethylenically unsaturated monomer and an oil-soluble dye has a low viscosity and an oil and is excellent in dyeability. Furthermore, when the ethylenically unsaturated monomer was polymerized after the ink was printed, the fine particles were changed to fine particles composed of an oil-soluble compound and a polymer, and the image storage stability, particularly the light fastness of the image could be improved. . Therefore, when the ink of the present invention is used with the recording material, an image having high image quality, high strength and excellent image fastness can be formed.

  The inkjet recording method in the image forming method of the present invention is not particularly limited, and is a known method, for example, a charge control method for ejecting ink using electrostatic attraction force, or a drop-on-demand method using vibration pressure of a piezo element. Method (pressure pulse method), acoustic ink jet method that changes the electrical signal into an acoustic beam, irradiates the ink and uses the radiation pressure to eject the ink, heat forms a bubble by heating the ink, and uses the generated pressure Any of the inkjet (Bubble Jet (registered trademark)) system and the like may be used. Of these, the drop-on-demand method (pressure pulse method) using the vibration pressure of the piezoelectric element is particularly preferable.

  The inkjet recording method includes a method of radiating a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method used is included.

  In the present invention, heat and radiation can be used for proceeding the polymerization of the monomer, and α rays, γ rays, X rays, ultraviolet rays, visible rays, electron rays and the like can be used as the radiation. Of these, ultraviolet rays and visible rays are preferably used from the viewpoint of cost and safety, and ultraviolet rays are more preferably used.

  The recorded matter of the present invention is a recorded matter recorded by the above-described method of the present invention, and the recorded matter refers to a recorded material on which images and characters are recorded.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 (Preparation of non-aqueous ink jet recording ink)
<Preparation of non-aqueous inkjet recording magenta ink 101>
Monomer: n-butyl acrylate / t-butyl acrylamide = 50/50
(PA-11 polymer raw material) 3.0g
Monomer: DPCA60 (Nippon Kayaku) 1.0g
Monomer: 1,6 hexanediol diacrylate
(HDDA Daicel UCB) 16.0g
N-ethyldiethanolamine 0.6g
Photopolymerization initiator: IRGACURE-1870 (bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-hexylphosphine oxide / 1-humanoxy-cyclohexyl-phenyl-ketone = 70/30 mixture) 0.3 g
Colorant: M-1 0.8g
The above components were mixed with stirring to obtain magenta ink 101.

<Preparation of non-aqueous ink jet recording inks 102 to 112>
In the adjustment of the magenta ink 101, the non-aqueous ink jet recording inks 102 to 112 of the present invention were used in the same manner as the magenta ink 101, except that the monomer type, usage ratio, and oil-soluble dye type were changed as shown in Table 1 below. Was made.

<Evaluation>
The inks 101 to 112 were printed on art paper with an inkjet printer (Microjet, experimental machine, printing density: 300 dpi, droplet ejection frequency: 4 KHz, number of nozzles: 64) to a density of ~ OD = 1.0. Then, an exposure process was performed immediately below the head with a Deep UV lamp (US-7 SP-7) under an energy of 100 mJ / m2.

<Print performance evaluation>
The cartridge was set in the printer, and after confirming the ejection of ink from all nozzles, an image was output on 10 sheets of A4 paper, and printing disturbance was evaluated according to the following criteria.
A: There was no disorder in printing from the start to the end of printing.
B: Disturbance of printing occasionally occurred from the start to the end of printing.
C: The printing was disturbed from the start to the end of printing.

<Sticky evaluation>
Touch the print surface with your finger,
A thing without stickiness (A)
Somewhat sticky (B)
What is extremely sticky (C)
And sensory evaluation in three stages.

<Abrasion resistance evaluation>
The art paper on which the image was formed was rubbed 10 times with an eraser for the image that had passed 30 minutes after the image was printed, and the change was observed. Evaluation was made in three stages, with A indicating no decrease in concentration, B indicating a slight decrease in concentration, and C indicating a large decrease in concentration.

<Light resistance evaluation>
The art paper on which the image was formed was irradiated with xenon light (85000 lx) for 4 days using a weather meter (Atlas C.I65), and the image density before and after the xenon irradiation was measured using a reflection densitometer (X-Rite310TR). It was measured and evaluated as a dye residual ratio. The reflection density was measured at -1.0. When the residual ratio of the dye was 90% or more, the evaluation was made in five stages: A, 89-80% as B, 79-70% as C, 69-50% as D, and less than 49% as E.

<Ozone resistance>
The ozone resistance was evaluated by measuring the concentration of the sample before and after storing the sample for 3 days under an ozone concentration of 5.0 ppm with X-rite 310 to determine the residual rate of the dye.
When the residual ratio of the dye was 90% or more, the evaluation was made in five stages: A, 89-80% as B, 79-70% as C, 69-50% as D, and less than 49% as E.
The results are summarized in Tables 2 and 3 below.

Example 2 (Preparation of water-based inkjet recording ink)
<Preparation of water-based inkjet recording magenta ink 201>
Dye (M-1) 0.45 g, n-butyl acrylate / t-butyl acrylamide = 50/50
(PA-11 polymer raw material) 4 g, Irgacure-1870 (bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-hexylphosphine oxide / 1-humanoxy-cyclohexyl-phenyl-ketone = 70/30 mixture 0.4 g) and 0.04 g of N-ethyldiethanolamine were mixed and dissolved in 17 g of ethyl acetate. On the other hand, a mixed liquid of 18 g of water and 0.4 g of Emar 20C (Kao Co., Ltd.) is prepared, and the ethyl acetate solution is combined, and emulsification is performed at a rotational speed of 10,000 rpm with a homogenizer. A total of 5 cycles were performed from 4 minutes to 1 minute from the stop. Then, it concentrated at 30 degreeC under pressure reduction, and prepared the colored fine particle dispersion of solid content 27%. The particle diameter of the colored fine particles in the colored fine particle dispersion was 73 nm in terms of volume average diameter.
The obtained emulsion and the following materials were mixed and filtered through a 0.45 μm filter to prepare magenta ink 201 for water-based inkjet recording.

・ Colored fine particle dispersion 60 parts ・ Diethylene glycol 5 parts ・ Glycerin 15 parts ・ Diethanolamine 1 part ・ Orphine E1010 1.1 parts ・ Water Total amount of 100 parts

<Preparation of water-based inkjet recording inks 202 to 207 and comparative water-based inkjet recording inks 208 to 211 of the present invention>
In the preparation of the water-based ink jet recording ink 201, the same method as that of the water-based ink jet recording ink 201 except that the type of oil-soluble dye, the type of monomer, and the use ratio were changed as shown in Table 4 below. Inks 202 to 207 were prepared. The amount of the polymerization initiator was used so that the mass ratio was ˜10% with respect to the amount of the polymerizable ethylenically unsaturated monomer. Further, comparative water-based inkjet recording inks 208 to 211 were similarly produced. In the water-based inkjet recording inks 201 to 211, the concentrations of diethylene glycol, glycerin, and other additives in the final ink are constant.

Note 1 PET-4A: Hentaerythritol tetraacrylate
V-65: 2,2'-azobis (2,4-dimethyl) valeronitrile

-Image recording and evaluation-
The prepared inks 201 to 211 are filled into a cartridge of an ink jet printer PX-V700 (manufactured by EPSON Corporation), and are used on an ink jet paper photo glossy paper “Image” (manufactured by Fuji Photo Film Co., Ltd.). After recording the image, the inks 201 to 204 and 206 to 211 were subjected to exposure processing at 500 mJ / cm @ 2 using a metal halide lamp, and the ink 205 was subjected to heat treatment at 120 DEG C. for 3 minutes. The following evaluation was performed about the obtained image. The evaluation results are shown in Table 5.

<Print performance evaluation>
The cartridge was set in the printer, and after confirming the ejection of ink from all nozzles, an image was output on 10 sheets of A4 paper, and printing disturbance was evaluated according to the following criteria.
A: There was no disorder in printing from the start to the end of printing.
B: Disturbance of printing occasionally occurred from the start to the end of printing.
C: The printing was disturbed from the start to the end of printing.

<Image stickiness>
Evaluate the stickiness of the recorded image, A (good) if there is no stickiness at all, B (permissible) if there is some stickiness, but not so much that it touches the contact, C ( It was evaluated in three stages as bad).

<Abrasion evaluation>
After printing and heating, the image after 30 minutes was rubbed with an eraser, and the presence or absence of density change of the image was visually evaluated. A sample in which almost no change in concentration was observed was designated as A (good), and a sample in which a change in concentration was observed was designated as B (poor).

<Water resistance evaluation>
The photo glossy paper on which the image was formed was dried at room temperature for 1 hour, then dipped in water for 30 seconds, naturally dried at room temperature, and observed for bleeding. Evaluation was made in three stages, with A indicating no bleeding, B indicating slight bleeding, and C indicating large bleeding.

<Light resistance evaluation>
The photo glossy paper on which the image is formed is irradiated with xenon light (85000 lx) through a TAC filter for 7 days using a weather meter (Atlas Ci65), and the image density before and after the xenon irradiation is measured with a reflection densitometer (X-Rite310TR). And measured as a residual ratio of the dye. Evaluation was made in three stages, with A as the residual ratio of 85% or more, B as 70% or more and less than 85%, and C as less than 70%.

<Ozone resistance>
The ozone resistance was evaluated by measuring the concentration of the sample before and after storing the sample for 3 days under an ozone concentration of 5.0 ppm with X-rite 310 to determine the residual rate of the dye.
When the residual ratio of the dye was 90% or more, the evaluation was made in five stages: A, 89-80% as B, 79-70% as C, 69-50% as D, and less than 49% as E.

As is apparent from the results of Tables 2 and 4, the oxygen permeability coefficient of the present invention is 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)] or less The following specific structure The ink for inkjet recording prepared by using the monomer having the above has excellent printing performance, no stickiness, and high scratch resistance, light resistance, and ozone resistance.
On the other hand, there are several comparative examples using ink jet recording inks adjusted using a monomer having an oxygen permeability coefficient exceeding 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)]. It can be seen that the performance is inferior.

Using ink for ink jet recording adjusted using a monomer whose oxygen permeability coefficient after polymerization is 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)] or less It is possible to provide an ink for ink jet recording and an ink jet recording method which do not cause clogging at the nozzle tip when printing or the like and are excellent in scratch resistance and light resistance.

Claims (9)

The polymer is characterized by containing a hydrophobic ethylenically unsaturated monomer having an oxygen permeability coefficient of 2.6 × 10 ⁻¹³ [m ³ (STP) · m / (s · m ² · kPa)] or less after polymerization. Ink composition.   2. The ink composition according to claim 1, wherein the hydrophobic ethylenically unsaturated monomer has a structural site capable of taking a hydrogen bond.   The ink composition according to claim 1 or 2, wherein the hydrophobic ethylenically unsaturated monomer has one or more selected from amide bonds, urethane bonds, glycidyl groups, and hydroxyl groups.   The ink composition according to claim 1, 2 or 3, further comprising an oil-soluble compound and a polymerization initiator.   The ink composition according to claim 4, wherein a liquid containing a hydrophobic ethylenically unsaturated monomer, an oil-soluble compound and a polymerization initiator is emulsified and dispersed in an aqueous medium.   The ink composition according to claim 4 or 5, wherein the oil-soluble compound is an oil-soluble dye.   The ink composition according to claim 6, wherein the oxidation potential of the oil-soluble dye is nobler than 1.0 V (vs SCE).   An ink composition according to any one of claims 1 to 7 comprising a step of recording an image on a recording material by an inkjet recording method, and a step of polymerizing a hydrophobic ethylenically unsaturated monomer thereafter. Image forming method.   A recorded matter recorded by the image forming method according to claim 8.