JP2016160388A - Aqueous ink composition, inkjet recording method and coloring body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ink composition exhibiting a color tone of neutral light black to deep black and especially excellent in color development property of a recording image.SOLUTION: There is provided an ink composition containing water, a water soluble dye and a water soluble ethylene glycol ether-based organic solvent, where the water soluble dye is a dye obtained by reacting a compound represented by the formula (2) with phenylene diamine after diazotization. (one of Rand Ris a hydroxyl group and the other is an amino group and m is 1 or 2)SELECTED DRAWING: None

Description

  The present invention relates to an aqueous ink composition, an ink jet recording method using the same, and a colored body.

  The ink jet recording method, which is one of various color recording methods, is a method of recording by generating small ink droplets and attaching them to various recording materials (paper, film, fabric, etc.). is there. This method is quiet because it does not generate sound because the recording head and the recording material are not in direct contact. In addition, it has been rapidly spreading in recent years due to the feature of being easy to downsize and speed up, and is expected to grow greatly in the future.

  Due to the recent development of inkjet technology, the improvement in printing speed in inkjet printing is remarkable. For this reason, ink jet recording intended for commercial printing and office use has been proposed. Conventionally, ink jet paper having an ink receiving layer has been used. However, ink that can be printed on cheaper paper has been demanded, and in particular, improvement in color development is strongly desired.

  Black ink is an important ink used for both monocolor and full color images. However, there are many technical difficulties in developing dyes that are both neutral in color and light color gamut, high in color density, and excellent in fastness. There are few things with sufficient performance. Therefore, generally, a black ink is prepared by mixing a plurality of various dyes. However, when an ink is prepared by mixing a plurality of dyes, the hue differs depending on the recording material compared to the case where the ink is prepared with a single dye; Cheap.

  By increasing the content of the dye in the ink, it is possible to increase the color developability of the printed matter. However, it is known that as the dye content increases, nozzle clogging due to the solidification of the dye in the vicinity of the ink jet nozzle, bleeding of the printed matter, and the like are likely to occur. Therefore, improvements other than increasing the dye content in the ink are strongly desired.

  An example of the black ink composition is disclosed in Patent Document 1, for example.

Moreover, the compound represented by Formula (2) described in this specification, and the dye obtained by making it react with phenylenediamine after diazotizing the compound are disclosed by patent documents 2 and 3.
Ink compositions using the water-soluble dyes described in this specification are disclosed in Patent Documents 4 and 5.

Japanese Patent No. 4281259 JP 2002-3740 A Patent No. 4332005 Japanese Patent No. 3189538 JP-A-8-170041

  An object of the present invention is to provide a water-based ink composition that exhibits a neutral light black to dark black hue and is particularly excellent in color developability of a recorded image.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a water-based ink composition having a specific configuration described below, and have completed the present invention.

That is, the present invention relates to the following 1) to 10).
1)
An ink composition containing at least water, a water-soluble dye and a water-soluble organic solvent,
Containing at least a compound represented by the following formula (1) as the water-soluble organic solvent,
An ink composition wherein the water-soluble dye is a dye obtained by reacting with a phenylenediamine after diazotizing a compound represented by the following formula (2).

(In the formula (1), n represents 1 to 3)

(In the formula (2), _one of R ₁ and R ₂ represents a hydroxy group, the other represents an amino group, and m represents 1 or 2.)
2)
The ink composition 3) according to 1) above, which further contains an alkanediol as the water-soluble organic solvent.
The ink composition according to 1), wherein the compound represented by the formula (2) is a compound represented by the following formula (3).

(In the formula (3), _one of R ₁ and R ₂ represents a hydroxy group and the other represents an amino group.)
4)
The ink composition according to 1), wherein the content of the compound represented by the formula (1) is 0.5 to 10% by mass with respect to the total mass of the ink composition.
5)
The water-soluble dye is C.I. I. The ink composition as described in 1) above, which is Direct Black 19.
6)
The ink composition according to any one of 1) to 5), which further contains at least one acetylene glycol surfactant.
7)
An ink jet recording method in which recording is performed by ejecting droplets of the ink composition according to any one of 1) to 6) according to a recording signal and attaching the droplets to a recording material.
8)
A colored body colored with the ink composition according to any one of 1) to 6).
9)
A colored body colored by the inkjet recording method of 7).
10)
The inkjet printer with which the container containing the ink composition as described in any one of said 1) -6) was loaded.

  According to the present invention, a water-based ink composition that exhibits a neutral light black to dark black hue and is excellent in color developability of a recorded image can be provided.

  In the present specification, “%” and “parts” including examples and the like are described on a mass basis unless otherwise specified. In the present specification, “CI” means “color index”.

The ink composition is a water-based ink composition and contains at least the compound represented by the formula (1) as a water-soluble organic solvent.
Specific examples of the compound represented by the formula (1) are ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether. Diethylene glycol monobutyl ether and triethylene glycol monobutyl ether are preferred, and diethylene glycol monobutyl ether is more preferred.
The content of the compound represented by the formula (1) with respect to the total mass of the ink composition is usually 0.5% to 10%, preferably 1% to 10%, more preferably 1% to 7%.

  The ink composition may further contain an alkanediol. The range of carbon number of the alkanediol is preferably C4-C8, more preferably C5-C8. Specific examples thereof include 1,2-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-pentanediol 1,2-hexanediol, 1,6 -Hexanediol, 1,2-octanediol and the like. Among these, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, or 1,2-octanediol is preferable, and 1,2-hexanediol is most preferable. .

  When the ink composition contains alkanediol, the content of alkanediol is usually 1% to 15%, preferably 1% to 10%, more preferably 1.5% to 6 with respect to the total mass of the ink composition. %.

The ink composition may contain a compound represented by the formula (1) and a water-soluble organic solvent other than alkanediol as long as the effects of the present invention are not impaired. Specific examples of such water-soluble organic solvents include, for example, C1-C4 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol and tert-butanol; N, N-dimethylformamide or N , N-dimethylacetamide and other carboxylic acid amides; 2-pyrrolidone, N-methylpyrrolidin-2-one and other lactams; 1,3-dimethylimidazolidin-2-one or 1,3-dimethylhexahydropyrimido-2 -Cyclic ureas such as -one; ketones or ketoalcohols such as acetone, methyl ethyl ketone, 2-methyl-2-hydroxypentan-4-one; cyclic ethers such as tetrahydrofuran, dioxane; ethylene glycol, 1,2-propylene glycol, 1,3-propyleneglyco Monomers, oligomers or polyalkylenes having C2-C6 alkylene units excluding the alkanediols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, thiodiglycol, dithiodiglycol, etc. Glycol or thioglycol; polyol (triol) such as glycerin, hexane-1,2,6-triol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether or tri C1-C3 polyhydric alcohols such as ethylene glycol monoethyl ether Kill ether; .gamma.-butyrolactone, or dimethyl sulfoxide, and the like.
Among these water-soluble organic solvents, 2-pyrrolidone, isopropyl alcohol, glycerin, diglycerin, and propylene glycol are preferable.

  The total content of the water-soluble organic solvent excluding the compound represented by the formula (1) and the alkanediol is usually 1% to 50%, preferably 10% to 50% with respect to the total mass of the ink composition. More preferably, it is 25% to 50%.

The water-soluble dye is a dye obtained by diazotizing the compound represented by the formula (2) and then reacting with phenylenediamine.
The dye obtained by the reaction with phenylenediamine includes a compound represented by the formula (2) in which at least one of two amino groups substituted at the para position of the azo group is diazotized, and phenylenediamine. By reacting, a dye in which at least one amino group of the compound represented by the formula (2) is apparently substituted with an azo group and bonded to a carbon atom of phenylenediamine is exemplified. That is, the number of substitutions of phenylenediamine in the dye obtained by the reaction is one or two based on the number of amino groups of the compound represented by formula (2).
_One of R ₁ and R ₂ represents an amino group, but this amino group preferably does not react with phenylenediamine.
The dye thus obtained is not a single dye but a dye mixture of a plurality of dyes. This dye mixture is generally used as a mixture without isolation of the respective dyes.
In formula (2), _one of R ₁ and R ₂ represents a hydroxy group and the other represents an amino group. That is, when R ₁ is a hydroxy group, R ₂ is an amino group, and when R ₁ is an amino group, R ₂ is a hydroxy group. M represents the number of substitution of the sulfo group whose substitution position is not specified, and represents an integer of 1 or 2.

In the compound represented by formula (2), the substitution position of each group whose substitution position is not specified is not particularly limited. Preferred substitution positions of each group are as follows.
The following formula (5) is a formula in which the substitution position of each group is added to the formula (3), and otherwise has the same meaning as the formula (3).
Using the number described in the following formula (5) as a substitution position,
R ₁ is the 1st position; R ₂ is the 6th, 7th or 8th position; the azo group is the 5th, 6th, 7th or 8th position; when m is 1, the sulfo group is the 3rd or 5th position; When 2, the sulfo group is preferably in the 3rd and 5th positions, the 3rd and 6th positions, or the 5th and 7th positions.
Moreover, the combination of the preferable substitution position of each group is as follows.
1. R ₁ is in position 1; R ₂ is in position 8; azo is in position 7; when m is 1, the sulfo group is in position 5; when m is 2, the sulfo group is in positions 3 and 5; 6th.
2. R ₁ is in the 1st position; R ₂ is in the 8th position; the azo group is in the 6th position; m is 2, and the sulfo groups are in the 5th and 7th positions.
3. R ₁ is in position 1; R ₂ is in position 6; the azo group is in position 5; m is 1 and the sulfo group is in position 3.
4). R ₁ is in position 1; R ₂ is in position 7; the azo group is in position 8; m is 1 and the sulfo group is in position 3.
R ₁ is more preferably a hydroxy group and R ₂ is more preferably an amino group.
Among the compounds represented by the formula (2), a preferable compound is a compound represented by the formula (3).

The compound represented by formula (2) can be prepared by a known method. For example, it can be easily prepared by reacting 1-amino-8-naphthol-3,6-disulfonic acid with a diazotized product of 2 equivalents or more of p-nitroaniline and reducing the resulting disazo compound. . It can also be prepared by the methods disclosed in Patent Documents 2 and 3.
As a raw material for synthesizing the compound represented by the formula (2), in addition to 1-amino-8-naphthol-3,6-disulfonic acid, 1-amino-8-naphthol-4,6-disulfonic acid, 1 -Amino-8-naphthol-2,4-disulfonic acid, 2-amino-8-naphthol-6-sulfone, 3-amino-8-naphthol-4-sulfonic acid and the like. Among these, 1-amino-8-naphthol-3,6-disulfonic acid or 1-amino-8-naphthol-4,6-disulfonic acid is preferable, and 1-amino-8-naphthol-3,6- Disulfonic acid is more preferred.

The water-soluble dye can be prepared from the compound represented by the formula (2) by a known method. For example, it can be prepared by diazotizing the compound represented by the formula (2) using sodium nitrite or the like to prepare the diazotized derivative of the formula (2) or a salt thereof and reacting with phenylenediamine.
Moreover, a water-soluble dye can also be prepared by the methods disclosed in Patent Documents 2 and 3.

  Examples of water-soluble dyes obtained by diazotizing the compound represented by formula (2) and then reacting with phenylenediamine are shown in Tables 1 to 4 below. Specific examples of water-soluble dyes are shown below. It is not limited to.

The water-soluble dye is generally a mixture, and is known to have two maximum absorption wavelengths in the visible region in a water-diluted solution. It is known that this maximum absorption wavelength varies depending on the chemical structure of the water-soluble dye to be obtained; even if the same raw material is used, it may vary depending on the synthesis method. The reason for the latter is that the maximum absorption wavelength varies depending on the mixing ratio in the dye mixture; the difference in the structure of by-products;
The water-soluble dye contained in the ink composition generally has a maximum absorption on the long wavelength side of 600 nm to 700 nm, preferably 620 nm to 680 nm. The maximum absorption on the short wavelength side is usually 450 nm to 580 nm, preferably 480 nm to 550 nm. When a water-soluble dye having two maximum absorption wavelengths in these ranges is contained, the remarkable effect of the present invention is obtained.

The water-soluble dye can be used as a salt.
Examples of the salt of the water-soluble dye include salts formed with inorganic or organic cations. Among them, specific examples of inorganic salts include salts formed with cations of elements of Group 1 or Group 2 of the periodic table of elements, and ammonium salts. Among these, preferred inorganic salts are lithium, sodium, potassium and ammonium salts.
Examples of the organic cation salt include, but are not limited to, salts formed with compounds represented by the following formula (4).

In the formula (4), Z ₁ , Z ₂ , Z ₃ and Z ₄ each independently represent a hydrogen atom, an alkyl group, a hydroxyalkyl group, or a hydroxyalkoxyalkyl group, but Z ₁ , Z ₂ , Z All of ₃ and Z ₄ are not hydrogen atoms.

As the alkyl group of Z ₁ , Z ₂ , Z ₃ and Z _{4 in} the formula (4), a C1-C4 alkyl group is preferable, and specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec -Butyl, t-butyl and the like.
Examples of hydroxyalkyl groups include hydroxy-C1-C4 alkyl groups such as hydroxymethyl, hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl, 2-hydroxybutyl and the like.
Examples of hydroxyalkoxyalkyl groups include hydroxyethoxymethyl, 2-hydroxyethoxyethyl, 3-hydroxyethoxypropyl, 2-hydroxyethoxypropyl, 4-hydroxyethoxybutyl, 3-hydroxyethoxybutyl, 2-hydroxyethoxybutyl, etc. A hydroxy C1-C4 alkoxy-C1-C4 alkyl group is mentioned, Among these, a hydroxyethoxy-C1-C4 alkyl group is preferable.
More preferred are hydrogen atoms; methyl; hydroxy-C1-C4 alkyl groups such as hydroxymethyl, hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl, 2-hydroxybutyl; Hydroxyethoxy-C1-C4 alkyl groups such as hydroxyethoxymethyl, 2-hydroxyethoxyethyl, 3-hydroxyethoxypropyl, 2-hydroxyethoxypropyl, 4-hydroxyethoxybutyl, 3-hydroxyethoxybutyl, 2-hydroxyethoxybutyl, etc. Can be mentioned.

Specific examples of Z ₁ , Z ₂ , Z ₃ and Z ₄ in formula (4) are shown in the following Table 5, but the compound represented by formula (4) is not limited to these specific examples.

  Preferred examples of the organic cation salt include monoethanolamine salts, diethanolamine salts, triethanolamine salts, monoisopropanolamine salts, diisopropanolamine salts, and triisopropanolamine salts.

  The ink composition may further include a toning dye in order to obtain a desired hue. The dye for toning is preferably a reactive dye, an acid dye or a direct dye, more preferably a direct dye, from the viewpoint of dyeability on a recording material.

  Specific examples of reactive dyes for toning include C.I. I. Reactive Yellow 2, 3, 18, 81, 84, 85, 95, 99, 102, etc. yellow; C.I. I. Oranges such as Reactive Orange 5, 9, 12, 13, 35, 45, 99; I. Brown, such as Reactive Brown 2, 8, 9, 17, 33; I. Reactive Red 3, 3: 1, 4, 13, 24, 29, 31, 33, 125, 151, 206, 218, 226, 245, etc. Red;

  Specific examples of the acid dye for toning include C.I. I. Acid Yellow 1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 40: 1, 42, 44, 49, 59, 59: 1, 61, 65, 72, 73, 79, 99, 104, 110, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 219: 1, 220, 230, 232, 235, 241, 242, 246, etc .; I. Acid Orange 3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, Oranges such as 144, 149, 152, 156, 162, 166, 168; I. Acid Brown 2, 4, 13, 14, 19, 28, 44, 123, 224, 226, 227, 248, 282, 283, 289, 294, 297, 298, 301, 355, 357, 413, etc .; C . I. Acid Red 1, 6, 8, 9, 13, 18, 27, 35, 37, 52, 54, 57, 73, 82, 88, 97, 97: 1, 106, 111, 114, 118, 119, 127, 131, 138, 143, 145, 151, 183, 195, 198, 211, 215, 217, 225, 226, 249, 251, 254, 256, 257, 260, 261, 264, 265, 266, 274, 276, 277, 289, 296, 299, 315, 318, 336, 337, 357, 359, 361, 362, 364, 366, 399, 407, 415 and the like;

  Specific examples of direct dyes for toning include C.I. I. Direct Yellow 8, 11, 12, 21, 28, 33, 39, 44, 49, 50, 85, 86, 87, 88, 89, 98, 100, 110, 132, 142, 144, 146, etc .; C . I. Orange of Direct Orange 17, 26, 39, 102, etc .; I. Direct Red 2, 4, 6, 9, 17, 23, 26, 28, 31, 39, 54, 55, 57, 62, 63, 64, 65, 68, 72, 75, 76, 79, 80, 81, 83 83: 1, 84, 89, 92, 95, 99, 111, 141, 173, 180, 184, 207, 211, 212, 214, 218, 221, 223, 224, 225, 226, 227, 232, 233 , 240, 241, 242, 243, 247 and the like;

  From the viewpoint of color development, among the above-mentioned toning dyes, C.I. I. Direct Yellow 86, 132, 142; C.I. I. Direct Orange 17, 39; C.I. I. Direct Red 80, 84, 227; C.I. I. Direct Brown 106, 125, 195; C.I. I. One or more dyes selected from the group consisting of Acid Red 249, 254; are preferred. Among these, C.I. I. More preferably, at least one dye selected from Direct Orange is used, and at least one other color dye is used in combination.

  The ink composition may further contain an ink preparation agent as necessary as a component other than those described above as long as the effects of the present invention are not impaired. Examples of the ink preparation agent include antiseptic / antifungal agents, pH adjusters, chelating reagents, rust inhibitors, water-soluble ultraviolet absorbers, water-soluble polymer compounds, dye solubilizers, antioxidants, and surfactants. .

  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. When it contains an antifungal agent, it is preferably used in an amount of 0.02% to 1% based on the total mass of the aqueous ink composition.

Examples of preservatives include organic sulfur, organic nitrogen sulfur, organic halogen, haloallylsulfone, iodopropargyl, N-haloalkylthio, nitrile, pyridine, 8-oxyquinoline, and benzothiazole. , Isothiazoline, dithiol, pyridine oxide, nitropropane, organotin, phenol, quaternary ammonium salt, triazine, thiazine, anilide, adamantane, dithiocarbamate, brominated indanone, benzyl Examples include bromoacetate-based and inorganic salt-based compounds.
An example of the organic halogen compound is sodium pentachlorophenol. Examples of pyridine oxide compounds include sodium 2-pyridinethiol-1-oxide. An example of the inorganic salt compound is anhydrous sodium acetate. Examples of isothiazoline compounds include 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 5- Chloro-2-methyl-4-isothiazolin-3-one magnesium chloride, 5-chloro-2-methyl-4-isothiazolin-3-one calcium chloride, 2-methyl-4-isothiazolin-3-one calcium chloride and the like It is done. Other antiseptic / antifungal agents include sodium sorbate, sodium benzoate and the like.

As the pH adjuster, any substance can be used as long as it can adjust the pH range of the ink composition to usually 7 or more, preferably 7 to 12, more preferably 7 to 10. Examples thereof include, for example, alkanolamines such as diethanolamine, triethanolamine and N-methyldiethanolamine; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide and potassium hydroxide; ammonium hydroxide (ammonia); lithium carbonate And alkali metal carbonates such as sodium carbonate, sodium hydrogen carbonate and potassium carbonate; inorganic bases such as potassium acetate, sodium silicate and disodium phosphate;
Among these, alkanolamines such as diethanolamine, triethanolamine and N-methyldiethanolamine are preferable, and diethanolamine and triethanolamine are more preferable.

  Examples of chelating reagents include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uracil diacetate, and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the water-soluble ultraviolet absorber include sulfonated benzophenone compounds, benzotriazole compounds, salicylic acid compounds, cinnamic acid compounds, and triazine compounds.

  Examples of the water-soluble polymer compound include polyvinyl alcohol, cellulose derivatives, polyamines and polyimines.

  Examples of the dye solubilizer include ε-caprolactam, ethylene carbonate, urea and the like. Among these, urea is preferable.

  As the antioxidant, 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, and heterocyclic rings.

Examples of the surfactant include known surfactants such as anionic, cationic, and nonionic surfactants.
Examples of anionic surfactants include alkyl sulfonates, alkyl carboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acyl amino acids and salts thereof, N-acyl methyl taurate, alkyl sulfate poly Oxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester, lauryl alcohol sulfate ester, alkylphenol type phosphate ester, alkyl type phosphate ester, alkyl allyl sulfone hydrochloride, diethyl sulfo Examples thereof include oxalate, diethyl hexyl sulfosuccinate, dioctyl sulfosuccinate and the like.
Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.
Examples of amphoteric surfactants include lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine and other imidazoline derivatives. Can be mentioned.
Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyaralkylalkyl Ether type such as ether; polyoxyethylene oleic acid; polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate Esters such as polyoxyethylene stearate; 2,4,7,9-tetramethyl-5-decyne-4,7-dio Acetylene glycol (alcohol) systems such as 3,6-dimethyl-4-octyne-3,6-diol and 3,5-dimethyl-1-hexyne-3ol (for example, Surfinol 104, 105 manufactured by Nisshin Chemical Co., Ltd.) , 82, 420, 440, 465, Olfine STG, etc.).
Of these, nonionic surfactants are preferred. Among them, Surfynol 420, 440 and 465 which are acetylene glycol surfactants are preferable.

The surface tension of the ink composition is usually 20 to 70 mN / m, preferably 25 to 60 mN / m.
The viscosity of the ink composition is usually 30 mPa · s or less, preferably 20 mPa · s or less. The lower limit is 0.1 mPa · s or more, preferably 1 mPa · s or more.

All the components contained in or that can be contained in the ink composition may contain a single type or a combination of two or more types.
Moreover, as said each component, maximum absorption wavelength, etc., the combination of preferable things is more preferable, and the combination of more preferable things is still more preferable. The same applies to combinations of preferable and more preferable, more preferable and further preferable.

In the preparation of the ink composition, the order in which the components are mixed is not particularly limited.
The water used for the preparation of the ink composition is preferably water with few inorganic impurities such as ion exchange water and distilled water.
In addition, if necessary, after the ink composition is prepared, fine filtration may be performed using a membrane filter or the like to remove impurities in the ink composition. In particular, when the ink composition is used for ink jet recording, it is preferable to perform microfiltration. The pore size of the filter used for microfiltration is usually 1 μm to 0.1 μm, preferably 0.8 μm to 0.1 μm.

The ink composition can be used in various fields. For example, it can be used for writing, water-based printing, information recording, and the like, and is particularly preferably used for inkjet recording.
Examples of the ink jet recording method using the ink composition include a method of performing recording by ejecting droplets of the ink composition in accordance with a recording signal and attaching them to a recording material.

When performing inkjet recording, an inkjet printer is generally used. There is no restriction | limiting in particular about the ink nozzle etc. with which the inkjet printer is provided, According to the objective, it can select suitably. For example, a known ink jet recording method such as a charge control method; a drop-on-demand method (pressure pulse method) using vibration pressure of a piezoelectric element; an acoustic ink jet method; a thermal ink jet, for example, a bubble jet (registered trademark) method; Can do.
In addition, the ink jet recording method is a method in which a large amount of ink having a small dye content called a photo ink is ejected in a small volume; a plurality of inks having substantially the same hue and different dye contents are used to improve image quality. A method of improving; or a method of using a color ink and a colorless and transparent ink in combination;

  The ink composition is preferably used as a black ink. Using this as a black ink and further using each ink composition such as magenta, cyan, yellow, and, if necessary, green, blue (or violet) and red (or orange), a full-color recorded image is obtained. be able to. At this time, the ink composition of each color can be poured into each container, and the container can be loaded into a predetermined position of the ink jet printer and used for ink jet recording in the same manner as the container containing the ink composition. .

The colored body means a substance colored by the ink composition, and is preferably a substance colored by the ink jet recording method.
The substance is not particularly limited as long as it can be colored by the ink composition. Among such substances, recording materials such as recording media such as paper and film; fibers and fabrics (cellulose, nylon, wool, etc.); leather; base materials for color filters;
Examples of the recording medium include surface-treated media, specifically, media having an ink receiving layer provided on a substrate such as paper, synthetic paper, and film, and media having no ink receiving layer in particular. .
The ink receiving layer is formed by, for example, impregnating or coating the base material with a cationic polymer; a porous white inorganic substance capable of adsorbing a dye in an ink composition such as porous silica, alumina sol, or special ceramics; Coating the surface of the base material together with a hydrophilic polymer such as polyvinylpyrrolidone; A recording medium provided with such an ink-receiving layer is usually called ink jet dedicated paper (film), glossy paper (film) or the like. Specific examples thereof include, for example, Pictorico manufactured by Asahi Glass Co., Ltd .; professional photo paper manufactured by Canon Inc., super photo paper, matte photo paper, glossy gold, platinum grade; photographic paper (gloss) manufactured by Seiko Epson Corporation, Photo Matte Paper, Photographic Paper Crispier (High Gloss); Premium Plus Photo Paper, Premium Glossy Film, Photo Paper, Advanced Photo Paper manufactured by Hewlett-Packard Japan; Photo-like QP manufactured by Konica Minolta Co., Ltd .; FUJIFILM Corporation For example, the painting photo finishing Pro;
On the other hand, examples of the recording medium not particularly provided with the ink receiving layer include plain paper, high-quality paper, and coated paper. Many types of plain paper are commercially available depending on the application. Examples of commercially available plain paper include: Double-sided fine plain paper manufactured by Seiko Epson Corporation; Color plain paper manufactured by Canon Inc .; Multipurpose Paper, All-in-one Printing Paper manufactured by Hewlett Packard; Mitsubishi Paper Industries Inkjet matte paper manufactured by Co., Ltd., trade name DL-9084; Premium multipurpose paper 4024 manufactured by Xerox Corporation; In addition, PPC (plain paper copy) paper and the like are plain paper.

The ink composition of the present invention exhibits a neutral gray to black hue, has an achromatic color on the recording material and a high print density, and gives a black recorded image of an ideal hue. In addition, the ink composition of the present invention has very good storage stability without solid precipitation, physical property change, hue change, etc. after long-term storage.
The ink composition of the present invention can be used for inkjet recording and writing instruments. In particular, when used as an inkjet ink, solid precipitation due to drying of the ink composition in the vicinity of the nozzle hardly occurs, and the ejector (recording head) is not blocked.
In addition, the ink composition of the present invention uses a continuous ink jet printer and is used by recirculating ink at a relatively long time interval; or when used intermittently by an on-demand ink jet printer. Does not cause changes in physical properties.
Furthermore, the image recorded with the ink composition of the present invention is excellent in various fastnesses such as water resistance, moisture resistance, ozone gas resistance, abrasion resistance, and light resistance, particularly water resistance. In addition, the recording material has excellent long-term storage stability, and particularly excellent in light resistance and water resistance together with the hue on plain paper. In addition, it is excellent in color rendering properties and sensor compatible characteristics in the near-infrared light region.

  EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.

[(A) Preparation of Ink Composition]
[Examples 1 to 13]
Each component described in Table 6 below was mixed and stirred for about 1 hour to obtain a solution, followed by filtration with a 0.45 μm membrane filter (trade name cellulose acetate filter paper manufactured by Advantech) for evaluation tests. Ink compositions of the respective examples were prepared. The numerical value of each component in Table 6 below means “part”.
In addition, C.C. I. Direct black 19 can be obtained by a known method, and a dye having a maximum absorption wavelength in an aqueous solution of 668 nm on the long wavelength side and 506 nm on the short wavelength side was used.

The abbreviations in Table 6 below have the following meanings.
DB19: C.I. I. Direct Black 19.
GL: glycerin.
PG: Propylene glycol.
BDG: Diethylene glycol monobutyl ether.
BTG: Triethylene glycol monobutyl ether.
1,5-PD: 1,5-pentanediol.
1,2-HD: 1,2-hexanediol.
1,6-HD: 1,6-hexanediol.
1,2-OD: 1,2-octanediol.
TEA: triethanolamine.
SF440: Surfynol 440, an acetylene glycol surfactant manufactured by Air Products.
GXL: Proxel GXL, an antifungal agent manufactured by Arch Chemical Co., Ltd.

[Comparative Examples 1 to 9]
Ink compositions of comparative examples for evaluation tests were prepared in the same manner as in Examples 1 to 13 except that the components described in Table 7 below were used. The numerical value of each component in the following Table 7 means “part”.
The ink compositions disclosed in Comparative Example 7 in Example 5 of Patent Document 4 and Comparative Example 8 in Example 1 of Patent Document 5 were respectively prepared as comparative ink compositions. Comparative Example 9 is a comparative ink composition in which the content of the dye contained in Comparative Example 8 is increased so as to be the same amount as in each Example.

Of the abbreviations and the like in Table 7 below, the same as in Table 6 have the same meaning as in Table 6.
Other abbreviations have the following meanings.
EG: ethylene glycol.
DEG: Diethylene glycol.
TEG: Triethylene glycol.
PEG200: Polyethylene glycol # 200.
PGMPE: propylene glycol monopropyl ether.

[(B) Inkjet recording]
The ink compositions prepared in each Example and Comparative Example were subjected to inkjet recording on the following plain papers 1 and 2 using an inkjet printer manufactured by Seiko Epson Corporation, trade name PX205.
Plain paper 1: Premium multi-purpose paper 4024 manufactured by Xerox Corporation.
Plain paper 2: Nippon Paper Industries Co., Ltd., fine paper, Npi fine green 70.
During ink jet recording, an image pattern is created so that six levels of gradations of 100%, 80%, 60%, 40%, 20%, and 10% density can be obtained, and a dark black to light black gradation recorded matter. Got. The following evaluation tests were carried out using this as a test piece.

[(C) Colorimeter and colorimetric conditions]
When color measurement was necessary in the following evaluation tests, color measurement was performed using the following colorimeter and color measurement conditions.
Colorimeter:
Product name SpectroEye manufactured by GRETAG-MACBETH.
Colorimetric conditions:
The density standard is ANSI A, the viewing angle is 2 °, and the light source is D50.

[(D) Hue evaluation test]
Among the test pieces of each of the examples and comparative examples obtained in “(B) Inkjet recording”, L *, a *, b * of the gradation portion of 100% density in the test piece using plain paper 1 The chroma C * value was calculated using the following formula.
C * = (a * ² + b * ² ) ^1/2
In addition, obtained C * is a preferable black hue, so that it is close to 0, and it evaluated it on the basis of the following four steps. In this standard, “B” or more is a normal practical black hue.
A: C * is less than 3.0.
B: C * is 3.0 or more and less than 4.0.
C: C * is 4.0 or more and less than 7.0.
D: C * is 7.0 or more.
The results are shown in Table 8 and Table 9 below.

[(F) Color development evaluation test]
Among the test pieces of each of the examples and comparative examples obtained in “(B) Inkjet recording”, the Dk value of the 100% density gradation portion of the test piece using the plain paper 2 was measured, and the following standard It was evaluated with.
A: Dk is 1.10 or more.
B: Dk is 1.05 or more and less than 1.10.
C: Dk is 1.00 or more and less than 1.05.
D: Dk is less than 1.00.
The results are shown in Table 8 and Table 9 below.

  As is clear from the results of Tables 8 and 9, it was revealed that each example gave an achromatic and high-quality black image. Furthermore, despite using the same water-soluble dye as each comparative example, it was confirmed that the Dk value was clearly high for each comparative example, and the ink composition of the present invention has extremely excellent color developability. It became clear.

  Since the ink composition of the present invention is excellent in hue and color developability, it is very suitably used for various recording applications, particularly inkjet recording.

Claims (10)

An ink composition containing at least water, a water-soluble dye and a water-soluble organic solvent,
Containing at least a compound represented by the following formula (1) as the water-soluble organic solvent,
An ink composition wherein the water-soluble dye is a dye obtained by reacting with a phenylenediamine after diazotizing a compound represented by the following formula (2).

(In the formula (1), n represents 1 to 3)

(In the formula (2), _one of R ₁ and R ₂ represents a hydroxy group, the other represents an amino group, and m represents 1 or 2.)   The ink composition according to claim 1, further comprising alkanediol as the water-soluble organic solvent. The ink composition according to claim 1, wherein the compound represented by the formula (2) is a compound represented by the following formula (3).

(In the formula (3), _one of R ₁ and R ₂ represents a hydroxy group and the other represents an amino group.)   2. The ink composition according to claim 1, wherein the content of the compound represented by the formula (1) is 0.5 to 10% by mass with respect to the total mass of the ink composition.   The water-soluble dye is C.I. I. The ink composition according to claim 1, which is Direct Black 19.   The ink composition according to any one of claims 1 to 5, further comprising at least one acetylene glycol surfactant.   An ink jet recording method for performing recording by ejecting the droplets of the ink composition according to any one of claims 1 to 6 in accordance with a recording signal and attaching the droplets to a recording material.   The colored body colored with the ink composition as described in any one of Claims 1-6.   A colored body colored by the inkjet recording method according to claim 7.   An ink jet printer loaded with a container containing the ink composition according to claim 1.