JP2008297541A - Ink for ink-jet, ink-jet recording method, ink cartridge, recording unit, and ink-jet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a yellow ink for ink-jet giving an image of excellent light resistance, color developing property, and color tone, and excellent in storage stability of the ink. <P>SOLUTION: This ink for ink-jet contains at least two color materials, a first color material and a second color material, and the first color material is a compound represented by general formula (I) and the second color material is a color material having a pH buffer capacity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet ink, an inkjet recording method, an ink cartridge, a recording unit, and an inkjet recording apparatus.

  The ink jet recording method is a recording method in which an ink droplet is applied to a recording medium such as plain paper or glossy media to form an image, and is rapidly spreading due to its low cost and high recording speed. Moreover, in addition to the progress of high image quality of images obtained by the ink jet recording method, with the rapid spread of digital cameras, it has become widely used as an image output method comparable to silver salt photography.

  In recent years, image quality has been improved more than ever due to the minimization of ink droplets and the improvement of the color gamut accompanying the introduction of multicolor ink. On the other hand, however, demands for color materials and inks are increasing, and more stringent characteristics are required in terms of reliability such as improved color development, clogging, and ejection stability.

  On the other hand, the problem of the ink jet recording method is that the obtained recorded matter is inferior in image storability. In general, the recorded matter obtained by the ink jet recording method has lower image storability than silver salt photographs. Specifically, when the recorded material is exposed to light, humidity, heat, or environmental gases that exist in the air for a long time, the color material on the recorded material deteriorates, causing a change in color tone or fading of the image. There is a problem that it is easy to do.

  Many proposals have heretofore been made in order to improve the light fastness of an image, particularly among image storability. For example, among the cyan, magenta, and yellow inks, a color material that can improve the light resistance of the image and can form an image with excellent color developability, particularly in a yellow ink having a low image light resistance. Has been proposed (see Patent Document 1).

  On the other hand, there is a proposal regarding an ink containing a material (buffering agent, etc.) having a pH buffering action for the purpose of suppressing the influence of ink pH change (precipitation of coloring material, corrosion on a member in contact with the ink, etc.). Yes (see Patent Documents 2 to 4).

International Publication No. 2006/082669 Pamphlet Japanese Patent Laid-Open No. 1-149872 JP-A-6-166840 JP-A-6-220386

  Among yellow, magenta, and cyan inks widely used as inkjet inks, yellow inks tend to be inferior in light resistance of images. Therefore, the present inventors considered that it is necessary to conduct a detailed study on the color material used for the yellow ink.

  Accordingly, an object of the present invention is to provide a yellow inkjet ink that gives an image excellent in light resistance, color developability, and color tone, and further has excellent storage stability of the ink. Another object of the present invention is to provide an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus using the ink jet ink.

（一般式（Ｉ）中、Ｒ₁、Ｒ₂、Ｙ₁及びＹ₂はそれぞれ独立に、一価の基であり、Ｘ₁及びＸ₂はそれぞれ独立に、ハメットのσｐ値が０．２０以上の電子吸引性基であり、Ｚ₁及びＺ₂はそれぞれ独立に、水素原子、置換若しくは無置換のアルキル基、置換若しくは無置換のアルケニル基、置換若しくは無置換のアルキニル基、置換若しくは無置換のアラルキル基、置換若しくは無置換のアリール基、又は置換若しくは無置換のヘテロ環基であり、Ｍは、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。） The above object is achieved by the present invention described below. That is, the ink-jet ink according to the present invention is an ink-jet ink containing at least two color materials, ie, a first color material and a second color material. It is a compound represented by the formula (I), and the second color material is a color material having a pH buffering ability.

(In general formula (I), R ₁ , R ₂ , Y ₁ and Y ₂ are each independently a monovalent group, and X ₁ and X ₂ are each independently having a Hammett's σp value of 0.20 or more. Z ₁ and Z ₂ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group An aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and M is a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

（一般式（III）中、Ｒは、水素原子、炭素数１乃至４のアルキル基、炭素数１乃至４のアルコキシ基、又はスルホン酸基であり、ｎは１又は２、ｍは１乃至３の整数、ｘは２乃至４の整数、ｙは１乃至３の整数であり、Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。） An ink-jet ink according to another embodiment of the present invention is characterized in that, in the ink-jet ink having the above-described configuration, the second color material is a compound represented by the following general formula (III). .

(In General Formula (III), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group, n is 1 or 2, and m is 1 to 3) X is an integer of 2 to 4, y is an integer of 1 to 3, and M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

  An ink jet recording method according to another embodiment of the present invention is an ink jet recording method in which ink is ejected by an ink jet method to perform recording on a recording medium, wherein the ink is an ink jet ink having the above-described configuration. And

  An ink cartridge according to another embodiment of the present invention is an ink cartridge provided with an ink containing portion for containing ink, wherein the ink is an inkjet ink having the above-described configuration.

  According to another embodiment of the present invention, there is provided a recording unit comprising an ink storage portion for storing ink and a recording head for discharging ink, wherein the ink is an inkjet ink having the above-described configuration. It is characterized by being.

  An ink jet recording apparatus according to another embodiment of the present invention is an ink jet recording apparatus having an ink containing portion for containing ink and a recording head for ejecting ink. Ink for use.

  According to the present invention, it is possible to provide a yellow inkjet ink that gives an image excellent in light resistance, color developability, and color tone, and further has excellent storage stability of the ink. Moreover, according to another embodiment of the present invention, an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus using the ink jet ink can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In the present invention, when the compound is a salt, the salt is dissociated into ions in the ink, but is expressed as “contains a salt” for convenience. Further, in the following description, the compound represented by the general formula (I) and the compound represented by the general formula (II) are represented by the “compound of the general formula (I)” and the “general formula (II)”, respectively. It may be abbreviated as “compound”. Furthermore, the compound represented by general formula (III) and the compound represented by general formula (IV) are abbreviated as “compound of general formula (III)” and “compound of general formula (IV)”, respectively. May be described.

  As described above, among yellow, magenta, and cyan inks widely used as inkjet inks, yellow inks tend to be inferior in light resistance of images. Accordingly, the present inventors have made various studies on the color material used for yellow ink. As a result, the compound of the following general formula (I) described in Patent Document 1 described above, and particularly the compound of the following general formula (II) among them, particularly focused on excellent light resistance and color developability. .

（一般式（Ｉ）中、Ｒ₁、Ｒ₂、Ｙ₁及びＹ₂はそれぞれ独立に、一価の基である。Ｘ₁及びＸ₂はそれぞれ独立に、ハメットのσｐ値が０．２０以上の電子吸引性基である。Ｚ₁及びＺ₂はそれぞれ独立に、水素原子、置換若しくは無置換のアルキル基、置換若しくは無置換のアルケニル基、置換若しくは無置換のアルキニル基、置換若しくは無置換のアラルキル基、置換若しくは無置換のアリール基、置換若しくは無置換のヘテロ環基。Ｍは、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In general formula (I), R ₁ , R ₂ , Y ₁ and Y ₂ are each independently a monovalent group. X ₁ and X ₂ are each independently having a Hammett's σp value of 0.20 or more. Z ₁ and Z ₂ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group An aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, and M is a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

（一般式（II）中、Ｙ₁及びＹ₂はそれぞれ独立に、一価の基であり、Ｘ₁及びＸ₂はそれぞれ独立に、ハメットのσｐ値が０．２０以上の電子吸引性基である。Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In General Formula (II), Y ₁ and Y ₂ are each independently a monovalent group, and X ₁ and X ₂ are each independently an electron-withdrawing group having a Hammett's σp value of 0.20 or more. M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

  However, the present inventors prepared an ink containing only the compound of the general formula (I) or the compound of the general formula (II) as a coloring material, and conducted various image studies and reliability studies. It turns out that there are two problems.

  The first problem is the problem of color tone and color gamut described below. It turned out that the color tone in the image formed using only the ink which contains only the compound of general formula (I) or the compound of general formula (II) as a coloring material is green. Further, it has been found that the color gamut, particularly the red color gamut, of an image formed by combining the ink with cyan ink and magenta ink having various hue angles is greatly lost.

  The second problem is the problem of the storage stability of the ink described below. First, an ink containing only the compound of the general formula (I) or the compound of the general formula (II) as a coloring material was prepared, and examination was performed using such an ink. Specifically, when such ink is mounted on a plurality of ink jet recording apparatuses and these ink jet recording apparatuses are left standing for a long period of time, and recovery properties are examined, ejection failure may occur in some ink jet recording apparatuses. all right. Further, when observing the nozzle of the recording head in which the ejection failure occurred, it was found that the color material was deposited near the nozzle.

  As a result of the study of these phenomena by the present inventors, the compound of the general formula (I) or the compound of the general formula (II) decreases in solubility from the neutral to the acidic pH range of the ink. Then, it turned out that a coloring material precipitates. Specifically, in the range where the pH is less than 7.0, an increase in the viscosity of the ink and a precipitation of the color material due to a decrease in solubility were observed. Specifically, it is considered that the following phenomenon occurs when an ink containing only one of the above compounds as a coloring material is left for a long period of time. That is, the pH of the ink changes due to elution of components from the ink or a member that contacts the water-soluble organic solvent in the ink. In addition, when the ejection port is capped with a cap constituting the recovery system of the inkjet recording apparatus, volatile components evaporated from the ejection port of another ink capped with the same cap are mixed from the ejection port of the ink. The pH of the ink changes. In addition, by operating the wiper that constitutes the recovery system, another ink is mixed from the ink ejection port, whereby the pH of the ink changes. Further, while the ink jet recording apparatus is left for a long period of time, the pH of the ink changes due to oxidation of the water-soluble organic solvent in the ink. Due to at least one of these phenomena, or other factors, the pH of the ink containing only the compound of the general formula (I) or the compound of the general formula (II) as a coloring material changes, and the viscosity or color of the ink increases. Precipitation of the material is considered to occur.

  Such an increase in the viscosity of the ink or precipitation of the coloring material due to the change in the pH of the ink is caused by, for example, a buffer such as sodium borate or an amine compound as described in Patent Documents 2 to 4 mentioned above. It was thought that this could be suppressed by adding an agent to the ink. However, according to the study by the present inventors, when recording is continuously performed using such an ink, there is a case where sufficient ejection stability cannot be obtained. In addition, the storage stability of the ink may not be sufficiently obtained due to the interaction between the buffer and the impurities in the ink. That is, it has been found that ink reliability may not be obtained.

  Therefore, the present inventors have a problem with conventional inks by using a colorant having a pH buffering capacity instead of the above buffering agent as a compound that can improve the color tone and suppress a change in pH. As a result of earnest investigation by obtaining the knowledge that it can be improved, the present invention has been achieved. That is, by using the compound represented by the general formula (I) as the first color material and using the second color material having pH buffering ability in combination with the ink, the above-described problems are solved. it can. Furthermore, the present inventors obtain excellent light resistance and color developability achieved when the compound of the general formula (I) or the compound of the general formula (II) is used as a color material. In order to solve the problems of the color tone and the storage stability of the ink, which were the issues, repeated investigations. In particular, a color material having the following three features required for that purpose was searched. That is, (1) a color material that can be adjusted to a preferred yellow color tone by mixing with a compound of general formula (I) or a compound of general formula (II), and (2) a color material excellent in light resistance and color development (3) A color material having a pH buffering ability was searched. As a result, it was found that the compound represented by the following general formula (III), particularly the compound represented by the following general formula (IV) is preferable. The pH buffering capacity in the present invention means that even if a certain amount of acid is added, it does not exceed a certain hydrogen ion concentration. The color material having pH buffering ability will be described later.

（一般式（III）中、Ｒは、水素原子、炭素数１乃至４のアルキル基、炭素数１乃至４のアルコキシ基、又はスルホン酸基であり、ｎは１又は２、ｍは１乃至３の整数、ｘは２乃至４の整数、ｙは１乃至３の整数である。Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In General Formula (III), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group, n is 1 or 2, and m is 1 to 3) X is an integer of 2 to 4, and y is an integer of 1 to 3. M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

（一般式（IV）中、Ｒは、水素原子、炭素数１乃至４のアルキル基、炭素数１乃至４のアルコキシ基、又はスルホン酸基であり、ｎは１又は２、ｌ（エル）は１又は２、ｘは２乃至４の整数、ｙは１乃至３の整数である。Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In General Formula (IV), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group, n is 1 or 2, and l (el) is 1 or 2, x is an integer of 2 to 4, y is an integer of 1 to 3. M is independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

  As described so far, the feature of the present invention is that the compound represented by the general formula (I) is used as the first color material, and the second color material having pH buffering ability is used in combination therewith. Inkjet ink. Particularly preferably, the compound represented by the general formula (I) is used as the first color material, and the compound of the general formula (II) is used as the first color material, and the general formula (III) is used as the second color material. ), And in particular, the compound of the general formula (IV) is used. As described above, the effect of the present invention can be obtained particularly remarkably by using a combination of a compound having a specific structure as the coloring material used in the ink. Hereinafter, the ink-jet ink of the present invention will be described in detail.

<Ink>
Hereinafter, components constituting the ink-jet ink according to the present invention (hereinafter sometimes simply referred to as ink), physical properties of the ink, and the like will be described in detail.

(Coloring material)
[First coloring material: compound represented by general formula (I) and compound represented by general formula (II)]
The ink of the present invention needs to contain a compound of the following general formula (I) having the characteristics of excellent light resistance and color development as the first coloring material. Among the compounds of the following general formula (I), it is particularly preferable to use a compound of the following general formula (II). Hereinafter, these general formulas will be described.

（一般式（Ｉ）中、Ｒ₁、Ｒ₂、Ｙ₁及びＹ₂はそれぞれ独立に、一価の基である。Ｘ₁及びＸ₂はそれぞれ独立に、ハメットのσｐ値が０．２０以上の電子吸引性基である。Ｚ₁及びＺ₂はそれぞれ独立に、水素原子、置換若しくは無置換のアルキル基、置換若しくは無置換のアルケニル基、置換若しくは無置換のアルキニル基、置換若しくは無置換のアラルキル基、置換若しくは無置換のアリール基、置換若しくは無置換のヘテロ環基。Ｍは、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In general formula (I), R ₁ , R ₂ , Y ₁ and Y ₂ are each independently a monovalent group. X ₁ and X ₂ are each independently having a Hammett's σp value of 0.20 or more. Z ₁ and Z ₂ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group An aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, and M is a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

（一般式（II）中、Ｙ₁及びＹ₂はそれぞれ独立に、一価の基であり、Ｘ₁及びＸ₂はそれぞれ独立に、ハメットのσｐ値が０．２０以上の電子吸引性基である。Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In General Formula (II), Y ₁ and Y ₂ are each independently a monovalent group, and X ₁ and X ₂ are each independently an electron-withdrawing group having a Hammett's σp value of 0.20 or more. M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

General formula (I) in R _1, R _2, Y ₁ and Y _2, and, Y ₁ and Y ₂ in the general formula (II) are each independently a monovalent group, specifically the following substitutions It can be based. Hydrogen atom, halogen atom, alkyl group, cycloalkyl group, aralkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, cyano group, hydroxyl group, nitro group, alkoxy group, aryloxy group, silyloxy group, heterocyclic ring Oxy group and acyloxy group. Carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (alkylamino group, arylamino group), acylamino group (amide group), aminocarbonylamino group (ureido group), alkoxycarbonylamino group. Aryloxycarbonylamino group, sulfamoylamino group, alkylsulfonylamino group, arylsulfonylamino group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, alkylsulfinyl group, arylsulfinyl group. An alkylsulfonyl group, an arylsulfonyl group, an acyl group, an aryloxycarbonyl group, and an alkoxycarbonyl group; Examples thereof include a carbamoyl group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a silyl group, an azo group, and an imide group. These groups may further have a substituent.

Among the above, the following substituents are particularly preferable. Hydrogen atom, halogen atom, alkyl group, aryl group, heterocyclic group, cyano group, alkoxy group, amide group, ureido group, alkylsulfonylamino group, arylsulfonylamino group, sulfamoyl group, alkylsulfonyl group. An arylsulfonyl group, a carbamoyl group, an alkoxycarbonyl group; Among these, a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, and a heterocyclic group are more preferable, and a hydrogen atom, an alkyl group, an aryl group, a cyano group, and an alkyl group are more preferable. A sulfonyl group is particularly preferred. In the present invention, it is particularly preferable that Y ₁ and Y ₂ in the general formula (II) are each independently the following substituents. A hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted hetero group Ring group.

Hereinafter, R ₁ , R ₂ , Y ₁ and Y ₂ in general formula (I) and general formula (II) will be described in more detail.
Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom. Among them, a chlorine atom or a bromine atom is preferable, and a chlorine atom is particularly preferable.

  Examples of the alkyl group include substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms. Specific examples include methyl, ethyl, butyl, t-butyl, n-octyl, eicosyl, 2-chloroethyl, hydroxyethyl, cyanoethyl, and 4-sulfobutyl.

  Examples of the cycloalkyl group include substituted or unsubstituted cycloalkyl groups having 5 to 30 carbon atoms. Specific examples include cyclohexyl, cyclopentyl, and 4-n-dodecylcyclohexyl.

  Examples of the aralkyl group include substituted or unsubstituted aralkyl groups having 7 to 30 carbon atoms. Specific examples include benzyl and 2-phenethyl.

  Examples of the alkenyl group include substituted or unsubstituted alkenyl groups having 2 to 30 carbon atoms. Specific examples include vinyl, allyl, prenyl, geranyl, oleyl, 2-cyclopenten-1-yl, and 2-cyclohexen-1-yl.

  Examples of the alkynyl group include substituted or unsubstituted alkynyl groups having 2 to 30 carbon atoms. Specific examples include ethynyl and propargyl.

  Examples of the aryl group include substituted or unsubstituted aryl groups having 6 to 30 carbon atoms. Specific examples include phenyl, p-tolyl, naphthyl, m-chlorophenyl, and o-hexadecanoylaminophenyl.

  A heterocyclic group is a 5-membered or 6-membered ring, and is a monovalent group obtained by removing one hydrogen atom from a substituted or unsubstituted aromatic or non-aromatic heterocyclic compound. It may be condensed. Among these, an aromatic heterocyclic group having a 5- or 6-membered ring having 3 to 50 carbon atoms is preferable. Examples of the heterocyclic group are pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, quinazoline, cinnoline, phthalazine, quinoxaline, pyrrole, indole, furan, benzofuran, and thiophene. Benzothiophene, pyrazole, imidazole, benzimidazole, triazole, oxazole, benzoxazole, thiazole, benzothiazole, isothiazole, benzisothiazole, thiadiazole, isoxazole, benzisoxazole. Examples include pyrrolidine, piperidine, piperazine, imidazolidine, thiazoline and the like.

  Examples of the alkoxy group include substituted or unsubstituted alkoxy groups having 1 to 30 carbon atoms. Specific examples include methoxy, ethoxy, isopropoxy, n-octyloxy, methoxyethoxy, hydroxyethoxy, and 3-carboxypropoxy.

  Examples of the aryloxy group include substituted or unsubstituted aryloxy groups having 6 to 30 carbon atoms. Specific examples include phenoxy, 2-methylphenoxy, 4-t-butylphenoxy, 3-nitrophenoxy, 2-tetradecanoylaminophenoxy and the like.

  Examples of the silyloxy group include silyloxy groups having 3 to 20 carbon atoms. Specific examples include trimethylsilyloxy and t-butyldimethylsilyloxy.

  Examples of the heterocyclic oxy group include substituted or unsubstituted heterocyclic oxy groups having 2 to 30 carbon atoms. Specific examples include 1-phenyltetrazol-5-oxy and 2-tetrahydropyranyloxy.

  Examples of the acyloxy group include a formyloxy group, a substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, and a substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms. Specific examples include formyloxy, acetyloxy, pivaloyloxy, stearoyloxy, benzoyloxy, p-methoxyphenylcarbonyloxy, and the like.

  Examples of the carbamoyloxy group include substituted or unsubstituted carbamoyloxy groups having 1 to 30 carbon atoms. Specific examples include N, N-dimethylcarbamoyloxy, N, N-diethylcarbamoyloxy, morpholinocarbonyloxy, N, N-di-n-octylaminocarbonyloxy, Nn-octylcarbamoyloxy and the like.

  Examples of the alkoxycarbonyloxy group include substituted or unsubstituted alkoxycarbonyloxy groups having 2 to 30 carbon atoms. Specific examples include methoxycarbonyloxy, ethoxycarbonyloxy, t-butoxycarbonyloxy, and n-octylcarbonyloxy.

  Examples of the aryloxycarbonyloxy group include substituted or unsubstituted aryloxycarbonyloxy groups having 7 to 30 carbon atoms. Specific examples include phenoxycarbonyloxy, p-methoxyphenoxycarbonyloxy, pn-hexadecyloxyphenoxycarbonyloxy, and the like.

  Examples of the amino group include substituted or unsubstituted alkylamino groups having 1 to 30 carbon atoms and substituted or unsubstituted arylamino groups having 6 to 30 carbon atoms. Specific examples include amino, methylamino, dimethylamino, anilino, N-methyl-anilino, diphenylamino, hydroxyethylamino, carboxyethylamino, sulfoethylamino, and 3,5-dicarboxyanilino. .

  Examples of the acylamino group include a formylamino group, a substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, and a substituted or unsubstituted arylcarbonylamino group having 6 to 30 carbon atoms. Specific examples include formylamino, acetylamino, pivaloylamino, lauroylamino, benzoylamino, and 3,4,5-tri-n-octyloxyphenylcarbonylamino.

  Examples of the aminocarbonylamino group include substituted or unsubstituted aminocarbonylamino groups having 1 to 30 carbon atoms. Specific examples include carbamoylamino, N, N-dimethylaminocarbonylamino, N, N-diethylaminocarbonylamino, morpholinocarbonylamino and the like.

  Examples of the alkoxycarbonylamino group include substituted or unsubstituted alkoxycarbonylamino groups having 2 to 30 carbon atoms. Specific examples include methoxycarbonylamino, ethoxycarbonylamino, t-butoxycarbonylamino, n-octadecyloxycarbonylamino, N-methyl-methoxycarbonylamino and the like.

  Examples of the aryloxycarbonylamino group include substituted or unsubstituted aryloxycarbonylamino groups having 7 to 30 carbon atoms. Specific examples include phenoxycarbonylamino, p-chlorophenoxycarbonylamino, and mn-octyloxyphenoxycarbonylamino.

  Examples of the sulfamoylamino group include substituted or unsubstituted sulfamoylamino groups having 0 to 30 carbon atoms. Specific examples include sulfamoylamino, N, N-dimethylaminosulfonylamino, Nn-octylaminosulfonylamino and the like.

  Examples of the alkylsulfonylamino group and arylsulfonylamino group include substituted or unsubstituted alkylsulfonylamino groups having 1 to 30 carbon atoms and substituted or unsubstituted arylsulfonylamino groups having 6 to 30 carbon atoms. Specific examples include methylsulfonylamino, butylsulfonylamino, phenylsulfonylamino, 2,3,5-trichlorophenylsulfonylamino, p-methylphenylsulfonylamino and the like.

  Examples of the alkylthio group include substituted or unsubstituted alkylthio groups having 1 to 30 carbon atoms. Specific examples include methylthio, ethylthio, and n-hexadecylthio.

  Examples of the arylthio group include substituted or unsubstituted arylthio groups having 6 to 30 carbon atoms. Specific examples include phenylthio, p-chlorophenylthio, and m-methoxyphenylthio.

  Examples of the heterocyclic thio group include substituted or unsubstituted heterocyclic thio groups having 2 to 30 carbon atoms. Specific examples include 2-benzothiazolylthio and 1-phenyltetrazol-5-ylthio.

  Examples of the sulfamoyl group include substituted or unsubstituted sulfamoyl groups having 0 to 30 carbon atoms. Specifically, N-ethylsulfamoyl, N- (3-dodecyloxypropyl) sulfamoyl, N, N-dimethylsulfamoyl, N-acetylsulfamoyl, N-benzoylsulfamoyl, N- (N '-Phenylcarbamoyl) sulfamoyl and the like.

  Examples of the alkylsulfinyl group and arylsulfinyl group include substituted or unsubstituted alkylsulfinyl groups having 1 to 30 carbon atoms and arylsulfinyl groups having 6 to 30 carbon atoms. Specific examples include methylsulfinyl, ethylsulfinyl, phenylsulfinyl, and p-methylphenylsulfinyl.

  Examples of the alkylsulfonyl group and the arylsulfonyl group include substituted or unsubstituted alkylsulfonyl groups having 1 to 30 carbon atoms and arylsulfonyl groups having 6 to 30 carbon atoms. Specific examples include methylsulfonyl, ethylsulfonyl, phenylsulfonyl, and p-toluenesulfonyl.

  The acyl group is a formyl group, a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyl group having 7 to 30 carbon atoms, and a substituted or unsubstituted carbon atom having 4 to 30 carbon atoms. Examples include a heterocyclic carbonyl group bonded to a carbonyl group. Specific examples include acetyl, pivaloyl, 2-chloroacetyl, stearoyl, benzoyl, pn-octyloxyphenylcarbonyl, 2-pyridylcarbonyl, and 2-furylcarbonyl.

  Examples of the aryloxycarbonyl group include substituted or unsubstituted aryloxycarbonyl groups having 7 to 30 carbon atoms. Specific examples include phenoxycarbonyl, o-chlorophenoxycarbonyl, m-nitrophenoxycarbonyl, pt-butylphenoxycarbonyl, and the like.

  Examples of the alkoxycarbonyl group include substituted or unsubstituted alkoxycarbonyl groups having 2 to 30 carbon atoms. Specific examples include methoxycarbonyl, ethoxycarbonyl, t-butoxycarbonyl, and n-octadecyloxycarbonyl.

  Examples of the carbamoyl group include substituted or unsubstituted carbamoyl groups having 1 to 30 carbon atoms. Specific examples include carbamoyl, N-methylcarbamoyl, N, N-dimethylcarbamoyl, N, N-di-n-octylcarbamoyl, N- (methylsulfonyl) carbamoyl, and the like.

  Examples of the phosphino group include substituted or unsubstituted phosphino groups having 2 to 30 carbon atoms. Specific examples include dimethylphosphino, diphenylphosphino, and methylphenoxyphosphino.

  Examples of the phosphinyl group include substituted or unsubstituted phosphinyl groups having 2 to 30 carbon atoms. Specific examples include phosphinyl, dioctyloxyphosphinyl, and diethoxyphosphinyl.

  Examples of the phosphinyloxy group include substituted or unsubstituted phosphinyloxy groups having 2 to 30 carbon atoms. Specific examples include diphenoxyphosphinyloxy and dioctyloxyphosphinyloxy.

  Examples of the phosphinylamino group include substituted or unsubstituted phosphinylamino groups having 2 to 30 carbon atoms. Specific examples include dimethoxyphosphinylamino and dimethylaminophosphinylamino.

  Examples of the silyl group include substituted or unsubstituted silyl groups having 3 to 30 carbon atoms. Specific examples include trimethylsilyl, t-butyldimethylsilyl, and phenyldimethylsilyl.

  Specific examples of the azo group include phenylazo, 4-methoxyphenylazo, 4-pivaloylaminophenylazo, 2-hydroxy-4-propanoylphenylazo, and the like.

  Specific examples of the imide group include N-succinimide and N-phthalimide.

  These substituents may be further substituted. Examples of the substituent in this case include the following. A linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched aralkyl group having 7 to 18 carbon atoms, and a linear or branched alkenyl group having 2 to 12 carbon atoms. A linear or branched alkynyl group having 2 to 12 carbon atoms, a linear or branched cycloalkyl group having 3 to 12 carbon atoms, and a linear or branched cycloalkenyl group having 3 to 12 carbon atoms. These substituents are preferably those having a branched chain, and more preferably those having an asymmetric carbon, in order to improve the solubility of the dye and the stability of the ink.

  Specific examples of the substituent include the following. Substituted or unsubstituted alkyl groups such as methyl, ethyl, propyl, isopropyl, sec-butyl, t-butyl, 2-ethylhexyl, 2-methylsulfonylethyl, 3-phenoxypropyl, trifluoromethyl, and cyclopentyl. Halogen atoms such as chlorine atom and bromine atom. Aryl groups such as phenyl, 4-t-butylphenyl, and 2,4-di-t-amylphenyl; Heterocyclic groups such as imidazolyl, pyrazolyl, triazolyl, 2-furyl, 2-thienyl, 2-pyrimidinyl, and 2-benzothiazolyl. Cyano group. Hydroxyl group. Nitro group. Carboxy group. Amino group. Alkyloxy groups such as methoxy, ethoxy, 2-methoxyethoxy, and 2-methylsulfonylethoxy; Aryloxy groups such as phenoxy, 2-methylphenoxy, 4-t-butylphenoxy, 3-nitrophenoxy, 3-t-butyloxycarbonylphenoxy, and 3-methoxycarbonylphenyloxy; Acylamino groups such as acetamide, benzamide, and 4- (3-t-butyl-4-hydroxyphenoxy) butanamide. Alkylamino groups such as methylamino, butylamino, diethylamino, and methylbutylamino; Anilino groups such as phenylamino and 2-chloroanilino. Ureido groups such as phenylureido, methylureido, and N, N-dibutylureido. Sulfamoylamino groups such as N, N-dipropylsulfamoylamino. Alkylthio groups such as methylthio, octylthio, and 2-phenoxyethylthio; Arylthio groups such as phenylthio, 2-butoxy-5-t-octylphenylthio, and 2-carboxyphenylthio; Alkyloxycarbonylamino groups such as methoxycarbonylamino; Alkyl or arylsulfonylamino groups such as methylsulfonylamino, phenylsulfonylamino, and p-toluenesulfonylamino; Carbamoyl groups such as N-ethylcarbamoyl and N, N-dibutylcarbamoyl. Sulfamoyl groups such as N-ethylsulfamoyl, N, N-dipropylsulfamoyl, and N-phenylsulfamoyl. Sulfonyl groups such as methylsulfonyl, octylsulfonyl, phenylsulfonyl, and p-toluenesulfonyl. Alkyloxycarbonyl groups such as methoxycarbonyl and butyloxycarbonyl; Heterocyclic oxy groups such as 1-phenyltetrazol-5-oxy and 2-tetrahydropyranyloxy. Azo groups such as phenylazo, 4-methoxyphenylazo, 4-pivaloylaminophenylazo, and 2-hydroxy-4-propanoylphenylazo; Acyloxy groups such as acetoxy. Carbamoyloxy groups such as N-methylcarbamoyloxy and N-phenylcarbamoyloxy. Silyloxy groups such as trimethylsilyloxy and dibutylmethylsilyloxy. Aryloxycarbonylamino groups such as phenoxycarbonylamino; Imido groups such as N-succinimide and N-phthalimide. Heterocyclic thio groups such as 2-benzothiazolylthio, 2,4-di-phenoxy-1,3,5-triazole-6-thio, and 2-pyridylthio. Sulfinyl groups such as 3-phenoxypropylsulfinyl. Phosphonyl groups such as phenoxyphosphonyl, octyloxyphosphonyl, and phenylphosphonyl. Aryloxycarbonyl groups such as phenoxycarbonyl. Acyl groups such as acetyl, 3-phenylpropanoyl, and benzoyl; Examples include ionic hydrophilic groups such as a carboxyl group, a sulfonic acid group, a phosphono group, and a quaternary ammonium group.

X ₁ and X ₂ in the general formulas (I) and (II) are electron-withdrawing groups having a Hammett σp value of 0.20 or more. Here, Hammett's rule and Hammett's substituent constant σp value (hereinafter referred to as “Hammett σp value”) will be described. Hammett's rule was established in 1935 by L. L. in order to quantitatively discuss the effect of substituents on the reaction and equilibrium of benzene derivatives. P. This is an empirical rule proposed by Hammett and is widely accepted today. Substituent constants determined by Hammett's rule include a σp value and a σm value, and these values are described in many general books. For example, there is a detailed description in JADean, Langes Handbook of Chemistry 12th edition, 1979, McGraw-Hill, Chemistry Domain, Special Issue, 122, 96-103, 1979, Nankodo.

  In the present invention, each substituent is defined by Hammett's σp value. However, the present invention is not limited to only the substituents whose σp values are specifically described in the above-mentioned literature. In the present invention, even if the σp value is not described in the literature as described above, when the σp value is calculated based on the Hammett rule, the substituent that will be included in the range is also included. Needless to say. Neither the compound of the general formula (I) nor the compound of the general formula (II) is a benzene derivative. However, in the present invention, the σp value is used as a scale indicating the electronic effect of the substituent regardless of the substitution position. To do. Specific examples of the substituent that can be used as an electron-withdrawing group having a Hammett σp value of 0.20 or more in the substituent of the compound of the general formula (I) or the compound of the general formula (II) of the present invention are as follows. Examples are listed for each range of Hammett σp values.

  Examples of the electron-withdrawing group having a Hammett σp value of 0.60 or more include the following. A cyano group, a nitro group, an alkylsulfonyl group (for example, an arylsulfonyl group such as a methanesulfonyl group or a benzenesulfonyl group).

In addition to the above, examples of the electron withdrawing group having a Hammett σp value of 0.45 or more include the following.
An acyl group (for example, acetyl group), an alkoxycarbonyl group (for example, dodecyloxycarbonyl group), an aryloxycarbonyl group (for example, m-chlorophenoxycarbonyl group). An alkylsulfinyl group (for example, n-propylsulfinyl group), an arylsulfinyl group (for example, phenylsulfinyl group); A sulfamoyl group (for example, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), a halogenated alkyl group (for example, trifluoromethyl group).

In addition to the above, examples of the electron-withdrawing group having a Hammett's σp value of 0.30 or more include the following.
Acyloxy group (for example, acetoxy group), carbamoyl group (for example, N-ethylcarbamoyl group, N, N-dibutylcarbamoyl group). A halogenated alkoxy group (for example, trifluoromethyloxy group), a halogenated aryloxy group (for example, pentafluorophenyloxy group); Sulfonyloxy group (for example, methylsulfonyloxy group), halogenated alkylthio group (for example, difluoromethylthio group). An aryl group substituted with an electron-withdrawing group having two or more σp values of 0.15 or more (for example, 2,4-dinitrophenyl group, pentachlorophenyl group). Heterocycle (for example, 2-benzoxazolyl group, 2-benzothiazolyl group, 1-phenyl-2-benzimidazolyl group).

  Examples of the electron-withdrawing group having a Hammett σp value of 0.20 or more include halogen atoms (for example, fluorine, chlorine, bromine) and the like.

Z ₁ and Z ₂ in the general formula (I) are each independently any of the substituents listed below. That is, a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted group Any one of the heterocyclic groups. Examples of the alkyl group include the same alkyl groups as those described above for R ₁ , R ₂ , Y ₁ and Y ₂ . Examples of the alkenyl group include the same alkenyl groups as those described above for R ₁ , R ₂ , Y ₁ and Y ₂ . Examples of the alkynyl group include the same alkynyl groups as mentioned above in the description of R ₁ , R ₂ , Y ₁ and Y ₂ . Examples of the aralkyl group include the same aralkyl groups as mentioned above in the description of R ₁ , R ₂ , Y ₁ and Y ₂ . Examples of the aryl group include the same aryl groups as those described above for R ₁ , R ₂ , Y ₁ and Y ₂ . Examples of the heterocyclic group include the same heterocyclic groups as those described above for R ₁ , R ₂ , Y ₁ and Y ₂ . Further, these substituents may be further substituted, and in this case, the substituents are listed as groups for further substituting the substituents previously mentioned in the description of R ₁ , R ₂ , Y ₁ and Y ₂ . The same as the group.

  M in general formula (I) and general formula (II) is a hydrogen atom, an alkali metal, ammonium, or organic ammonium each independently. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the organic ammonium include acetamide, benzamide, methylamino, butylamino, diethylamino, and phenylamino.

  Preferable specific examples of the compound of the general formula (I) or the compound of the general formula (II) include the following exemplified compounds 1 to 14. In addition, the following exemplary compounds are described in the form of a free acid. Of course, the present invention is not limited to the following exemplified compounds as long as they are included in the structure of the general formula (I) or the general formula (II) and the definition thereof. In the present invention, it is particularly preferable to use the exemplified compounds 5, 6, 7, 8, and 10 among the following exemplified compounds.

[Example of Second Coloring Material: Compound Represented by General Formula (III) and Compound Represented by General Formula (IV)]
In the ink of the present invention, in addition to the compound of the general formula (I) or the compound of the general formula (II) described above used as the first color material, a color material having a pH buffering ability is used. Used in combination as the second colorant. Therefore, as the second color material, any color material having ink pH buffering ability can be used. In the present invention, it is preferable to use a compound of the following general formula (III) as the second color material, and among the color materials having such a structure, it is preferable to use a compound of the following general formula (IV). Hereinafter, the compounds of these general formulas will be described. The compound of the following general formula (III) and the compound of the following general formula (IV) are excellent in light resistance and color developability and are characterized by having pH buffering ability. Furthermore, the compound of the following general formula (III) and the compound of the following general formula (IV) can be used in combination with the compound of the above general formula (I) or the compound of the above general formula (II) to obtain a synergistic effect. The ink can form an image having a preferable yellow tone.

（一般式（III）中、Ｒは、水素原子、炭素数１乃至４のアルキル基、炭素数１乃至４のアルコキシ基、又はスルホン酸基である。ｎは１又は２、ｍは１乃至３の整数、ｘは２乃至４の整数、ｙは１乃至３の整数である。Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In General Formula (III), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group. N is 1 or 2, and m is 1 to 3) X is an integer of 2 to 4, and y is an integer of 1 to 3. M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

（一般式（IV）中、Ｒは、水素原子、炭素数１乃至４のアルキル基、炭素数１乃至４のアルコキシ基、又はスルホン酸基である。ｎは１又は２、ｌ（エル）は１又は２の整数、ｘは２乃至４の整数、ｙは１乃至３の整数である。Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In the general formula (IV), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group. N is 1 or 2, and l (el) is (An integer of 1 or 2, x is an integer of 2 to 4, and y is an integer of 1 to 3. Each M is independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

  R in general formula (III) and general formula (IV) is the following substituents. That is, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group can be given. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Moreover, M in general formula (III) and general formula (IV) is a hydrogen atom, an alkali metal, ammonium, or organic ammonium each independently. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the organic ammonium include acetamide, benzamide, methylamino, butylamino, diethylamino, and phenylamino.

  Preferable specific examples of the compound of the general formula (III) or the compound of the general formula (IV) include the following exemplified compounds 15 to 49. The following exemplary compounds are described in the form of free acid. Of course, the present invention is not limited to the following exemplary compounds as long as they are included in the structure of the general formula (III) or the general formula (IV) and the definition thereof. In the present invention, it is particularly preferable to use the exemplified compound 16 among the following exemplified compounds.

[Color material verification method]
To verify whether or not the color material used in the present invention is contained in the ink, the following verification methods (1) to (3) using high performance liquid chromatography (HPLC) can be applied.
(1) Peak retention time (2) Maximum absorption wavelength for peak at (1) (3) M / Z (posi), M / Z (nega) of mass spectrum for peak at (1)

The analysis conditions of high performance liquid chromatography are as follows. A liquid (ink) diluted about 1,000 times with pure water was used as a measurement sample. And the analysis by a high performance liquid chromatography was performed on the following conditions, and the retention time (retention time) of a peak and the maximum absorption wavelength of a peak were measured.
Column: SunFire C ₁₈ (Nippon Waters) 2.1 mm x 150 mm
-Column temperature: 40 ° C
・ Flow rate: 0.2 mL / min
PDA: 200 nm to 700 nm
-Mobile phase and gradient conditions: Table 1 below

The analysis conditions of the mass spectrum are as shown below. About the obtained peak, a mass spectrum is measured on condition of the following, and M / Z detected most strongly is measured with respect to each of posi and negative.
・ Ionization method ・ ESI
Capillary voltage: 3.5 kV
Desolvent gas: 300 ° C
Ion source temperature: 120 ° C
Detector posi: 40V 200-1500amu / 0.9sec
nega: 40V 200-1500amu / 0.9sec

  Under the method and conditions described above, as representative examples of the respective color materials, exemplary compound 5 which is a specific example of the first color material and exemplary compound 16 which is a specific example of the second color material were measured. As a result, the obtained retention time, maximum absorption wavelength, M / Z (posi), and M / Z (negative) values are shown in Table 2. When the unknown ink is measured under the same method and conditions as described above and corresponds to the values shown in Table 2, it can be determined that it corresponds to the compound used in the present invention.

[Content of coloring material]
The content (mass%) of the first color material (the compound of general formula (I) or general formula (II)) in the ink is 0.1 mass% or more and 10.0 mass% based on the total mass of the ink. The following is preferable. Further, the content (% by mass) of the second color material in the ink (as a representative example, the compound of the general formula (III) or the general formula (IV)) is 0.1% by mass based on the total mass of the ink. The content is preferably 10.0% by mass or less.

  The total content (% by mass) of the first color material and the second color material in the ink is 1.0% by mass or more and 10.0% by mass or less based on the total mass of the ink. It is preferable. Furthermore, the total (mass%) of these contents is particularly preferably 1.5% by mass or more and 6.0% by mass or less. If the total content is less than 1.0% by mass, the light resistance and color developability of the image to be formed may not be sufficiently obtained. If the total content exceeds 10.0% by mass, the anti-adhesion property Ink jet characteristics such as property may not be obtained.

  The content (mass%) of the first color material, based on the total mass of the ink, is a mass ratio with respect to the content (mass%) of the second color material (first color material / first 2 coloring material) = 0.1 times or more and 10.0 times or less is preferable. More specifically, {content of compound of general formula (I) or general formula (II) / content of compound of general formula (III) or general formula (IV)} = 0.1 times or more and 10.0 It is preferable that it is less than 2 times. By setting the mass ratio of the content within the above range, the light resistance, color developability, color tone, and ink storage stability of the image can be obtained particularly effectively. In the present invention, {content of compound of general formula (I) or general formula (II) / content of compound of general formula (III) or general formula (IV)} = 1.0 times or more and 5.0 It is more preferable that the ratio is not more than twice. Combination of the light resistance of the compound of general formula (I) or general formula (II) and the light resistance of the compound of general formula (III) or general formula (IV) by setting the content ratio in the above range A high level of light fastness that far exceeds the performance predicted from the can be obtained.

  Although the above-described first color material and second color material are used at a specific mass ratio, a synergistic effect is exhibited and the reason why light resistance exceeding prediction is obtained is not clearly clear, but the present invention They speculate as follows. Since the compounds of the general formula (I) or the general formula (II) are originally low in solubility, when an ink containing these compounds is applied to a recording medium, association and aggregation of color materials occur immediately after that. The association or aggregation tends to improve the fastness of the color material on the recording medium on which the image is formed. On the other hand, however, excessive association or aggregation may reduce the light fastness inherent in the molecular structure. On the other hand, when a compound such as general formula (III) or general formula (IV) coexists, the compound of general formula (I) or general formula (II) is optimal in terms of light resistance on the recording medium. It is considered that the light resistance was improved by forming a state of association or aggregation.

  When the inkjet ink of the present invention is a yellow ink, the preferred color tone for the yellow ink means the following two things. That is, it means that an image formed using only yellow ink is not reddish or greenish. In addition to this, when forming a secondary color image formed using yellow ink, that is, an image of a red region or a green region, both the color region of the red region and the green region may be greatly lost. Means having no color tones. More specifically, the hue angle of an image formed using only yellow ink is preferably 85 ° to 92 °, and more preferably 88 ° to 90 °.

[PH buffering capacity]
The pH buffering ability in the present invention means that even if a certain amount of acid is added, it does not exceed a certain hydrogen ion concentration. The “coloring material having pH buffering ability” refers to a coloring material that does not exceed a certain hydrogen ion concentration even when a certain amount of acid is added to the liquid (ink) containing the coloring material. The “coloring material having pH buffering ability” in the present invention specifically means that when 20 μL of a 2.8N nitric acid aqueous solution is added to 20 mL of an aqueous solution containing 50 mmol / L of the coloring material, the pH is 7. It shall mean a colorant that is 0 or more. For example, since the exemplified compound 16 satisfies these conditions, it corresponds to the color material having pH buffering ability in the present invention. For an ink whose color material is unknown, the presence or absence of the pH buffering ability of the color material contained in the ink can be verified as follows, for example. First, a color material is separated from the ink by preparative chromatography or the like, and the molecular weight of the obtained color material can be measured using a high performance liquid chromatography mass spectrometer or the like. Thereafter, in the same manner as described above, the presence or absence of the buffer capacity of the color material is confirmed.

  As a result of detailed studies by the present inventors, the following knowledge has been obtained regarding the ink comprising the color material having the pH buffering ability and the compound of the general formula (I) or the compound of the general formula (II). It was. That is, an ink containing a combination of these coloring materials hardly changes in pH even when stored for a long period of time, and further suppresses precipitation of the compound of general formula (I) or the compound of general formula (II). I found out that This is presumably because the color material having the pH buffering ability (second color material) serves as a buffer and suppresses the change in the pH of the ink.

[Ink pH]
The ink of the present invention preferably has a pH of 7.0 or more and 10.0 or less. This is because if the pH of the ink exceeds 10.0, the following problems may occur depending on the type of the material constituting the member that contacts the ink of the ink cartridge or the ink jet recording apparatus. That is, impurities may elute into the ink from members that come into contact with the ink, and the ink performance may deteriorate. Moreover, the material which comprises the member which contacts ink may deteriorate. Furthermore, when recording is performed continuously for a long period of time, deterioration (dissolution) of the liquid contact surface of the heat generating part of the recording head or disconnection of the wiring may occur. On the other hand, when the pH of the ink is less than 7.0, the solubility of the compound of the general formula (I) or the compound of the general formula (II) is lowered, so that the storage stability of the ink may be lowered.

[Aqueous medium]
In the ink of the present invention, water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent can be used. It is preferable to use deionized water (ion exchange water) as the water. The content (% by mass) of water in the ink is preferably 10.0% by mass or more and 90.0% by mass or less based on the total mass of the ink.

  The water-soluble organic solvent is not particularly limited as long as it is water-soluble, and alcohol, polyhydric alcohol, polyglycol, glycol ether, nitrogen-containing polar solvent, sulfur-containing polar solvent and the like can be used. The content (% by mass) of the water-soluble organic solvent in the ink is 5.0% by mass or more and 90.0% by mass or less, and further 10.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. It is preferable that When the content of the water-soluble organic solvent is less than the above range, reliability such as ejection stability may not be obtained when the ink is used in an ink jet recording apparatus. Further, if the content of the water-soluble organic solvent is larger than the above range, the viscosity of the ink is increased and ink supply failure may occur.

  Specifically, for example, the following water-soluble organic solvents can be used. Alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol; Amides such as dimethylformamide and dimethylacetamide. Ketones or ketoalcohols such as acetone and diacetone alcohol. Ethers such as tetrahydrofuran and dioxane. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Glycols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, hexylene glycol, and thiodiglycol. 2 alkylene groups such as 1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,2,6-hexanetriol Alkylene glycols having 6 to 6 carbon atoms. Bis (2-hydroxyethyl) sulfone. Lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate. Alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether. N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. Of course, the present invention is not limited to these. These water-soluble organic solvents can be used alone or in combination of two or more as required.

[Other additives]
In addition to the components described above, the ink of the present invention contains a water-soluble organic compound that is solid at room temperature, such as polyhydric alcohols such as trimethylolpropane and trimethylolethane, and urea derivatives such as ethyleneurea, as necessary. You may contain. Further, the ink of the present invention is optionally provided with a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, a reduction inhibitor, an evaporation accelerator, a chelating agent, and a water-soluble agent. You may contain various additives, such as a polymer.

<Other inks>
Further, in order to form a full-color image or the like, the ink of the present invention can be used in combination with an ink having a color tone different from that of the ink of the present invention. The ink of the present invention is preferably used together with at least one kind of ink selected from, for example, black ink, cyan ink, magenta ink, yellow ink, red ink, green ink, and blue ink. Further, so-called light ink having substantially the same color tone as these inks can be used in combination. The color material of these inks or light inks may be a known dye or a newly synthesized color material.

<Recording medium>
As the recording medium used for forming an image using the ink of the present invention, any recording medium can be used as long as the recording medium is provided with ink. In the present invention, it is preferable to use an ink jet recording medium in which a coloring material such as a dye or a pigment is adsorbed to fine particles forming the porous structure of the ink receiving layer. In particular, it is preferable to use a recording medium having a so-called gap absorption type ink receiving layer that absorbs ink by voids formed in the ink receiving layer on the support. The gap absorption type ink receiving layer is composed mainly of fine particles, and may further contain a binder and other additives as necessary.

  Specifically, the following fine particles can be used. Inorganic pigments such as aluminum oxide such as silica, clay, talc, calcium carbonate, kaolin, alumina or alumina hydrate, diatomaceous earth, titanium oxide, hydrotalcite, or zinc oxide. Organic pigments such as urea formalin resin, ethylene resin, styrene resin. These fine particles can be used alone or in combination of two or more as required.

  Examples of the binder include water-soluble polymers and latex. Specifically, the following can be used. Polyvinyl alcohol, starch, gelatin, or modified products thereof. Arabic gum. Cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, or hydroxypropylmethylcellulose. Vinyl-based copolymer latex such as SBR latex, NBR latex, methyl methacrylate-butadiene copolymer latex, functional group-modified polymer latex, or ethylene vinyl acetate copolymer. Polyvinyl pyrrolidone. Maleic anhydride or a copolymer thereof, or an acrylate copolymer. These binders can use 1 type (s) or 2 or more types as needed.

  In addition, additives can be used as necessary. For example, dispersants, thickeners, pH adjusters, lubricants, fluidity modifiers, surfactants, antifoaming agents, mold release agents, optical brighteners, ultraviolet absorbers, antioxidants, dye fixing agents, etc. Can be used.

  In particular, when an image is formed using the ink of the present invention, it is preferable to use a recording medium in which an ink receiving layer is formed mainly of fine particles having an average particle diameter of 1 μm or less. Specific examples of the fine particles include silica fine particles and aluminum oxide fine particles. A preferable silica fine particle is a silica fine particle typified by colloidal silica. Although a colloidal silica can also use a commercial item, it is preferable to use especially the colloidal silica described in patent 2803134, 2881847, for example. Further, preferable examples of the aluminum oxide fine particles include alumina hydrate fine particles (alumina pigments).

Among the alumina pigments, an alumina hydrate such as pseudoboehmite represented by the following formula can be particularly preferable.
AlO _3-n (OH) _2n · mH ₂ O
(In the formula, n is an integer of 1 to 3, and m is 0 to 10, preferably 0 to 5. However, m and n are not 0 at the same time.)
mH ₂ O often also represents a detachable aqueous phase that is not involved in the formation of the mH ₂ O crystal lattice. For this reason, m can take an integer or a non-integer value. Also, when this type of alumina hydrate is heated, m can reach zero.

  Alumina hydrate can be produced by the following known methods. For example, it can be produced by hydrolysis of aluminum alkoxide or hydrolysis of sodium aluminate described in US Pat. No. 4,242,271 and US Pat. No. 4,202,870. Moreover, it can manufacture by the method of adding aqueous solution, such as sodium sulfate and aluminum chloride, to aqueous solution, such as sodium aluminate described in Japanese Patent Publication No.57-44605.

  The recording medium preferably has a support for supporting the ink receiving layer. The support is not particularly limited as long as the ink receiving layer can be formed of the above-described porous fine particles and gives rigidity that can be transported by a transport mechanism such as an ink jet recording apparatus. Can also be used. For example, a paper support composed of a pulp raw material mainly composed of natural cellulose fibers can be used. In addition, a plastic support made of a material such as polyester (for example, polyethylene terephthalate), cellulose triacetate, polycarbonate, polyvinyl chloride, polypropylene, or polyimide can be used. Furthermore, a resin-coated paper (eg, RC paper) having a polyolefin resin coating layer added with a white pigment or the like on at least one surface of the base paper can be used.

<Inkjet recording method>
The ink of the present invention is used in the ink jet recording method of the present invention in which recording is performed on a recording medium by ejecting the ink by an ink jet method. Ink jet recording methods include a recording method in which ink is ejected by applying mechanical energy to the ink, and a recording method in which ink is ejected by applying thermal energy to the ink. In particular, in the present invention, an ink jet recording method using thermal energy can be preferably used.

<Ink cartridge>
As an ink cartridge suitable for performing recording using the ink of the present invention, the ink cartridge of the present invention provided with an ink storage portion for storing such ink can be mentioned.

<Recording unit>
As a recording unit suitable for performing recording using the ink of the present invention, there is a recording unit of the present invention provided with an ink storage portion for storing such ink and a recording head for discharging the ink. In particular, a recording unit in which the recording head ejects ink by applying thermal energy corresponding to the recording signal to the ink can be preferably used. In particular, in the present invention, it is preferable to use a recording head having a heat generating part wetted surface containing a metal and / or a metal oxide. Specific examples of the metal and / or metal oxide constituting the heat generating part wetted surface include, for example, metals such as Ta, Zr, Ti, Ni, and Al, and oxides of these metals. .

<Inkjet recording apparatus>
As an ink jet recording apparatus suitable for performing recording using the ink of the present invention, an ink jet recording apparatus of the present invention including an ink storage portion for storing such ink and a recording head for discharging the ink can be cited. It is done. In particular, there is an ink jet recording apparatus that ejects ink by applying thermal energy corresponding to a recording signal to ink inside a recording head having an ink storage portion that stores the ink.

  Below, the schematic structure of the mechanism part of an inkjet recording device is demonstrated. The ink jet recording apparatus is composed of a paper feed unit, a transport unit, a carriage unit, a paper discharge unit, a cleaning unit, and an exterior unit that protects these parts and provides design properties in accordance with the role of each mechanism.

  FIG. 1 is a perspective view of the ink jet recording apparatus. 2 and 3 are diagrams for explaining the internal mechanism of the ink jet recording apparatus. FIG. 2 is a perspective view from the upper right part, and FIG. 3 is a side sectional view of the ink jet recording apparatus.

  When paper is fed, only a predetermined number of recording media are fed to a nip portion composed of a paper feed roller M2080 and a separation roller M2041 in a paper feed unit including a paper feed tray M2060. The recording medium is separated at the nip portion, and only the uppermost recording medium is conveyed. The recording medium conveyed to the conveyance unit is guided by the pinch roller holder M3000 and the paper guide flapper M3030, and conveyed to the roller pair of the conveyance roller M3060 and the pinch roller M3070. The roller pair of the conveyance roller M3060 and the pinch roller M3070 is rotated by driving of the LF motor E0002, and the recording medium is conveyed on the platen M3040 by this rotation.

  When forming an image on a recording medium, the carriage unit arranges a recording head H1001 (FIG. 4; a detailed configuration will be described later) at a position where a target image is formed, and follows a signal from the electric board E0014. Ink is ejected onto the recording medium. An image is formed on the recording medium by alternately repeating main scanning in which the carriage M4000 scans in the column direction while recording is performed by the recording head H1001 and sub-scanning in which the recording medium is conveyed in the row direction by the conveyance roller M3060. The recording medium on which the image is formed is conveyed in a state sandwiched between the nips of the first paper discharge roller M3110 and the spur M3120 at the paper discharge unit, and is discharged to the paper discharge tray M3160.

  The cleaning unit cleans the recording head H1001 before and after forming an image. When the pump M5000 is operated with the cap M5010 capping the ejection port of the recording head H1001, unnecessary ink or the like is sucked from the ejection port of the recording head H1001. In addition, by sucking ink remaining in the cap M5010 with the cap M5010 open, sticking due to the remaining ink and other problems do not occur.

[Configuration of recording head]
The configuration of the head cartridge H1000 will be described. FIG. 4 is a diagram showing the configuration of the head cartridge H1000, and is a diagram showing how the ink cartridge H1900 is mounted on the head cartridge H1000. The head cartridge H1000 has a recording head H1001, means for mounting the ink cartridge H1900, and means for supplying ink from the ink cartridge H1900 to the recording head, and is detachably mounted on the carriage M4000.

  The ink jet recording apparatus forms an image with yellow, magenta, cyan, black, light magenta, light cyan, and green inks. Therefore, the ink cartridge H1900 is also prepared for seven colors independently. In the above, the ink of the present invention is used as at least one ink. As shown in FIG. 4, each ink cartridge H1900 is detachable from the head cartridge H1000. The ink cartridge H1900 can be attached and detached even when the head cartridge H1000 is mounted on the carriage M4000.

  FIG. 5 is an exploded perspective view of the head cartridge H1000. The head cartridge H1000 includes a recording element substrate, a plate, an electric wiring substrate H1300, a cartridge holder H1500, a flow path forming member H1600, a filter H1700, a seal rubber H1800, and the like. The recording element substrate is composed of a first recording element substrate H1100 and a second recording element substrate H1101, and the plate is composed of a first plate H1200 and a second plate H1400.

  The first recording element substrate H1100 and the second recording element substrate H1101 are Si substrates, and a plurality of recording elements (nozzles) for ejecting ink are formed on one side thereof by a photolithography technique. Electric wiring such as Al for supplying electric power to each recording element is formed by a film forming technique, and a plurality of ink flow paths corresponding to individual recording elements are formed by a photolithography technique. Further, an ink supply port for supplying ink to the plurality of ink flow paths is formed to open on the back surface.

  FIG. 6 is an enlarged front view illustrating the configuration of the first recording element substrate H1100 and the second recording element substrate H1101. H2000 to H2600 are arrays of printing elements corresponding to different ink colors (hereinafter also referred to as nozzle arrays). On the first recording element substrate H1100, nozzle rows for three colors, a nozzle row H2000 for yellow ink, a nozzle row H2100 for magenta ink, and a nozzle row H2200 for cyan ink, are formed. On the second recording element substrate H1101, nozzle rows for four colors, a light cyan ink nozzle row H2300, a black ink nozzle row H2400, a green ink nozzle row H2500, and a light magenta ink nozzle row H2600, are formed. ing.

Each nozzle row is composed of 768 nozzles arranged at an interval of 1200 dpi (dot / inch; reference value) in the recording medium conveyance direction (sub-scanning direction). Each nozzle ejects about 2 picoliters of ink. For this reason, the opening area in each discharge port is set to about 100 μm ² .

  Hereinafter, a description will be given with reference to FIGS. The first recording element substrate H1100 and the second recording element substrate H1101 are bonded and fixed to the first plate H1200. Here, an ink supply port H1201 for supplying ink to the first recording element substrate H1100 and the second recording element substrate H1101 is formed. Further, a second plate H1400 having an opening is bonded and fixed to the first plate H1200. The second plate H1400 holds the electrical wiring substrate H1300 so that the electrical wiring substrate H1300 is electrically connected to the first recording element substrate H1100 and the second recording element substrate H1101.

  The electrical wiring substrate H1300 applies an electrical signal for ejecting ink from each nozzle formed on the first recording element substrate H1100 and the second recording element substrate H1101. The electric wiring board H1300 is arranged on the electric wiring corresponding to the first recording element substrate H1100 and the second recording element substrate H1101, and an external part for receiving an electric signal from the ink jet recording apparatus. And a signal input terminal H1301. The external signal input terminal H1301 is positioned and fixed on the back side of the cartridge holder H1500.

  A flow path forming member H1600 is fixed to the cartridge holder H1500 that holds the ink cartridge H1900, for example, by ultrasonic welding, and forms an ink flow path H1501 that communicates from the ink cartridge H1900 to the first plate H1200. A filter H1700 is provided at the ink cartridge side end of the ink flow path H1501 that engages with the ink cartridge H1900, and can prevent dust from entering from the outside. Further, a seal rubber H1800 is attached to the engaging portion with the ink cartridge H1900 so that the ink can be prevented from evaporating from the engaging portion.

  Furthermore, as described above, the head cartridge H1000 is configured by bonding the cartridge holder portion and the recording head portion H1001 by bonding or the like. The cartridge holder portion includes a cartridge holder H1500, a flow path forming member H1600, a filter H1700, and a seal rubber H1800. The recording head portion H1001 includes a first recording element substrate H1100, a second recording element substrate H1101, a first plate H1200, an electric wiring substrate H1300, and a second plate H1400.

  Here, as an embodiment of the recording head, a thermal ink jet recording head that performs recording using an electrothermal transducer (recording element) that generates thermal energy for causing ink to cause film boiling in accordance with an electrical signal. Said. About this typical structure and principle, for example, what is performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 is preferable. . This method can be applied to both a so-called on-demand type and a continuous type.

  The thermal ink jet method is particularly effective when applied to an on-demand type. In the case of the on-demand type, at least one drive that applies a rapid temperature rise exceeding nucleate boiling corresponding to the recording information to the electrothermal transducer disposed corresponding to the liquid flow path holding the ink Apply a signal. As a result, thermal energy is generated in the electrothermal transducer, and film boiling occurs in the ink. As a result, bubbles in the ink corresponding to the drive signal on a one-to-one basis can be formed. At least one droplet is formed by ejecting ink through the ejection port by the growth and contraction of the bubbles. It is more preferable that the driving signal has a pulse shape, since the bubble grows and contracts immediately and appropriately, so that ink discharge with particularly excellent response can be achieved.

  The ink of the present invention is not limited to the thermal ink jet method, and can be preferably used in an ink jet recording apparatus using mechanical energy as described below. An ink jet recording apparatus having such a configuration includes a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed to face the nozzles, and ink filling the periphery of the pressure generating element. Become. Then, the pressure generating element is displaced by the applied voltage, and ink is ejected from the nozzle.

  As described above, the ink jet recording apparatus is not limited to one in which the recording head and the ink cartridge are separated from each other. Further, the ink cartridge is integrated with the recording head in a separable or non-separable manner and mounted on the carriage, and is provided at a fixed portion of the ink jet recording apparatus via an ink supply member such as a tube. An ink may be supplied to the recording head. Further, when the ink cartridge is provided with a configuration for applying a preferable negative pressure to the recording head, the following configuration can be adopted. That is, a mode in which an absorber is disposed in the ink storage portion of the ink cartridge, or a mode in which a flexible ink storage bag and a spring portion that applies a biasing force in the direction of expanding the inner volume of the flexible ink storage bag are provided. It can be. The ink jet recording apparatus may take the form of a line printer in which recording elements are aligned over a range corresponding to the entire width of the recording medium, in addition to the serial type recording method described above.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example and a comparative example, this invention is not limited at all by the following Example, unless the summary is exceeded. In the item “Preparation of coloring material” below, “part” or “%” is based on mass unless otherwise specified.

<Preparation of coloring material>
[Synthesis of Exemplified Compound 5 and Measurement of Characteristic Values]
Exemplified Compound 5 (potassium salt) was synthesized according to the following synthesis flow and procedure.

(1) Synthesis of Compound b 25.5 g of sodium hydrogen carbonate and 150 mL of ion-exchanged water were mixed and heated to 40 ° C., and 25.0 g of cyanuric chloride (manufactured by Tokyo Chemical Industry; compound a) was added to this every 5 minutes. Added in equal portions and stirred for 1 hour to prepare a solution. The obtained solution was dropped into a mixed liquid (8 ° C.) of 52.8 mL of hydrazine monohydrate and 47 mL of ion-exchanged water so that the internal temperature did not exceed 10 ° C. Thereafter, the internal temperature was raised to 50 ° C. and stirred for 30 minutes. The precipitated crystals were filtered to obtain 23.4 g of compound b (hydrazine derivative, melting point> 300 ° C.). The yield was 94.7%.

(2) Synthesis of Compound c 35.0 g of the compound b (hydrazine derivative) obtained above was suspended in 420 mL of ethylene glycol, and stirred at an internal temperature of 50 ° C. To this, 59 mL of concentrated hydrochloric acid was added, and then 60.1 g of pivaloyl acetonitrile (manufactured by Tokyo Chemical Industry) was added and stirred at a temperature of 50 ° C. for 10 hours. To this, 95 mL of concentrated hydrochloric acid and 145 mL of methanol were added, and the mixture was further stirred for 8 hours. After cooling to room temperature, the precipitated crystals were collected by filtration to obtain 81.6 g of compound c (5-aminopyrazole derivative, melting point = 233-235 ° C.). The yield was 94.2%.

(3) Synthesis of Compound e 90.57 g of Compound d (manufactured by Tokyo Chemical Industry) was suspended in 500 mL of water, and 130 mL of concentrated hydrochloric acid was added thereto, and cooled until the internal temperature after addition was 5 ° C. or lower. did. Next, 70 mL of an aqueous solution containing 36.23 g of sodium nitrite was added dropwise in the range of the internal temperature of 4 to 6 ° C., and the internal temperature was kept at 5 ° C. or lower and stirred for 30 minutes. Next, 159 g of sodium sulfite and 636 mL of water were added while keeping the internal temperature at 20 ° C. or less, 250 mL of concentrated hydrochloric acid was added at an internal temperature of 25 ° C., and then the internal temperature was 90 ° C. for 1 hour. Stir. Thereafter, the internal temperature was cooled to room temperature, followed by filtration, washing with 200 mL of water, and then air drying to obtain 80.0 g of compound e.

(4) Synthesis of Compound f 23.3 g of Compound e obtained above was suspended in 209 mL of ethanol, and 28 mL of triethylamine was added dropwise thereto at room temperature. Thereafter, 12.2 g of ethoxymethylenemalononitrile (manufactured by ALDRICH) was added in several portions thereto. The mixture was further refluxed for 3 hours, cooled to room temperature, filtered, washed with 400 mL of isopropyl alcohol, and dried to obtain 23.57 g of compound f.

(5) Synthesis of Exemplified Compound 5 Acetic acid (145.56 mL) was added to sulfuric acid (32.4 mL) at an internal temperature of 4 ° C. or lower, and the internal temperature was maintained at 7 ° C. or lower, and 15.9 mL of 40% by mass nitrosyl sulfuric acid (manufactured by ALDRICH) ) Was added dropwise. To this, 32.4 g of the compound f obtained above was added in several portions, and the internal temperature was 10 ° C., followed by stirring for 60 minutes. Thereafter, a diazonium salt of compound f was added dropwise to a solution obtained by suspending 18.8 g of compound c added with 1.83 g of urea in 470 mL of methanol with an internal temperature of less than 0 ° C., and the internal temperature was reduced to less than 0 ° C. For 30 minutes. Thereafter, the internal temperature of the reaction solution was raised to room temperature, followed by filtration, washing with methanol, and further washing with water to obtain crude crystals. The obtained crude crystals were suspended in 400 mL of methanol, stirred for 60 minutes under reflux, then cooled to room temperature, filtered, washed with methanol, water, and methanol in this order, and then overnight at 75 ° C. Drying gave 34.4 g of free acid crystals of exemplary compound 5. The obtained crystals were dissolved in water to form a 10% by mass aqueous solution (25 ° C .: pH≈8.3: adjusted with KOH aqueous solution), and then crystallized by adding isopropanol at an internal temperature of 50 ° C., followed by cooling. Then, it was filtered, washed with isopropanol and dried. In this way, 35.0 g of Exemplified Compound 5 (potassium salt) was obtained.

(6) Measurement of characteristic value of Exemplified Compound 5 With respect to Exemplified Compound 5 obtained above, λ _max value and ε value in water were measured, and the results are shown in Table 3. The absorbance was measured under the following conditions.
・ Spectrophotometer: Self-recording spectrophotometer (trade name: U-3300; manufactured by Hitachi, Ltd.)
・ Measurement cell: 1 cm quartz cell ・ Sampling interval: 0.1 nm
・ Scanning speed: 30nm / min

[Synthesis of Example Compound 2 and Measurement of Characteristic Values]
Exemplified compound 2 was synthesized in the same manner as the above-described exemplary compound 5 synthesis flow except that compound d in the synthesis flow of exemplified compound 5 was changed to 2-amino-1,4-benzenedisulfonic acid. Table 3 shows the λ _max value and ε value of Exemplified Compound 2 obtained in water. The absorbance measurement conditions are the same as in Example Compound 5.

[Synthesis of Example Compound 3 and Measurement of Characteristic Values]
Exemplified Compound 3 was synthesized in the same manner as the above-described Synthetic Flow of Exemplified Compound 5, except that Compound d in the synthetic flow of Exemplified Compound 5 was changed to 5-amino-1,3-benzenedisulfonic acid. Table 3 shows the λ _max value and ε value of Exemplified Compound 3 obtained in water. The absorbance measurement conditions are the same as in Example Compound 5.

[Synthesis of Exemplified Compound 6 and Measurement of Characteristic Values]
Except for changing the ethoxymethylenemalononitrile used for the synthesis of Compound f to 2- (1-ethoxyethylidene) malononitrile in the synthesis flow of Illustrative Compound 5, it is exemplified in the same manner as the aforementioned Synthesis Compound 5 Synthesis Flow. Compound 6 was synthesized. Table 3 shows the λ _max value and ε value of Exemplified Compound 6 in water. The absorbance measurement conditions are the same as in Example Compound 5.

[Synthesis of Exemplified Compound 7 and Measurement of Characteristic Values]
A 5-amino-3-tert-butylpyrazole-4-carbonitrile synthesized by a conventional method is diazotized with sodium nitrite under acidic conditions, and the resulting compound is converted into Compound c in the synthesis flow of Exemplary Compound 5. And coupled. The obtained compound was dissolved in dimethylacetamide, 5-chloroisophthalic acid was added thereto, potassium carbonate was further added, and the internal temperature was stirred at 150 ° C. Thereafter, the internal temperature of the reaction solution was cooled to room temperature, filtered, and washed according to the same procedure as the synthesis flow of Exemplified Compound 5 to synthesize Exemplified Compound 7. Table 3 shows the λ _max value and ε value of Exemplified Compound 7 in water. The absorbance measurement conditions are the same as in Example Compound 5.

[Synthesis of Exemplified Compound 16 and Measurement of Characteristic Values]
(1) Synthesis of azo compound represented by formula (a) 17.3 parts of 3-aminobenzenesulfonic acid was dissolved in 200 parts of water while adjusting the pH to 6 with sodium hydroxide, and then sodium nitrite 7.2. Parts were added. This solution was adjusted to a temperature of 0 to 10 ° C. and dropped into 300 parts of 5% hydrochloric acid over 30 minutes, followed by stirring at 10 ° C. or lower for 1 hour to carry out a diazotization reaction to prepare a diazonium salt.

  In addition, 12.3 parts of 2-methoxyaniline was dissolved in 130 parts of water while adjusting the pH to 5 with sodium hydroxide, and was usually used with 10.4 parts of sodium bisulfite and 8.6 parts of 35% formalin. The methyl-ω-sulfonic acid derivative was obtained by the method. The obtained methyl-ω-sulfonic acid derivative was added to the previously prepared diazonium salt, and the mixture was stirred at a temperature of 0 to 15 ° C. and a pH of 2 to 4 for 5 hours. The resulting reaction solution was adjusted to pH 11 with sodium hydroxide and then stirred at a temperature of 80 to 95 ° C. for 5 hours while maintaining the pH at 11. To this, 100 parts of sodium chloride was added for salting out, and the precipitated solid was collected by filtration to obtain 100 parts of an azo compound represented by the following formula (a) as a wet cake.

(2) Synthesis of azo compound represented by formula (b) 17.3 parts of 3-aminobenzenesulfonic acid was dissolved in 200 parts of water while adjusting the pH to 6 with sodium hydroxide, and then 7.2 parts of sodium nitrite Was added. This solution was adjusted to a temperature of 0 to 10 ° C. and dropped into 300 parts of 5% hydrochloric acid over 30 minutes, followed by stirring at 10 ° C. or lower for 1 hour to carry out a diazotization reaction to prepare a diazonium salt.

  Also, 23.1 parts of 2-sulfopropoxyaniline was dissolved in 130 parts of water while adjusting the pH to 5 with sodium hydroxide, and 10.4 parts of sodium bisulfite and 8.6 parts of 35% formalin were used. A methyl-ω-sulfonic acid derivative was obtained by a conventional method. The obtained methyl-ω-sulfonic acid derivative was added to the previously prepared diazonium salt, and the mixture was stirred at a temperature of 0 to 15 ° C. and a pH of 2 to 4 for 5 hours. The resulting reaction solution was adjusted to pH 11 with sodium hydroxide and then stirred at a temperature of 80 to 95 ° C. for 5 hours while maintaining the pH at 11. To this, 100 parts of sodium chloride was added for salting out, and the precipitated solid was collected by filtration to obtain 130 parts of an azo compound represented by the following formula (b) as a wet cake.

(3) Synthesis of Exemplified Compound 16 and Measurement of Characteristic Values Next, 0.10 parts of Leocol TD90 (trade name; manufactured by Lion, surfactant) was added to 250 parts of ice water and stirred vigorously, and cyanuric chloride was added thereto. 8.0 parts were added, and it stirred at the temperature of 0-5 degreeC for 30 minutes, and obtained suspension. The wet cake of 100 parts of the azo compound represented by the formula (a) obtained above was dissolved in 200 parts of water, and the suspension obtained above was added dropwise thereto over 30 minutes. Thereafter, the mixture was stirred at a temperature of 0 to 10 ° C. and a pH of 5 to 6 for 6 hours to obtain a solution. Furthermore, the wet cake of 130 parts of the azo compound represented by the formula (b) obtained above was dissolved in 300 parts of water and added dropwise to the solution over 30 minutes. Then, it stirred for 6 hours as temperature 25-35 degreeC and pH 6-7, Furthermore, 18.8 parts of taurines were added, and it stirred for 3 hours as temperature 75-80 degreeC and pH 7-9, and obtained the reaction liquid. After the obtained reaction liquid was cooled to a temperature of 20 to 25 ° C., 800 parts of acetone was added to the reaction liquid and stirred at a temperature of 20 to 25 ° C. for 1 hour to precipitate a solid. The precipitated solid was collected by filtration to obtain 95.0 parts of a wet cake. This wet cake was dried with a hot air drier at a temperature of 80 ° C. to obtain 30.0 parts of Exemplary Compound 16 (water-soluble azo compound). The λ _max value of Exemplified Compound 16 obtained above in water was λ _max = 391 nm. The absorbance measurement conditions are the same as in Example Compound 5.

[Synthesis of Example Compound 50 and Measurement of Characteristic Values]
Diazotized 4-nitro-4′-aminostilbene-2,2-disulfonic acid and 3-aminonaphthalene-1-sulfonic acid were coupled. The resulting reaction product was triazolized, and the nitro group was reduced to an amino group by a known method to obtain aminostilbene-triazole. This aminostilbene-triazole was dissolved in water, and sodium nitrite and hydrochloric acid were added dropwise thereto for diazotization. This was dropped into an aqueous solution of a compound represented by the following formula (c), coupled, and then salted out with sodium chloride. The obtained compound was diazotized with an aqueous sodium nitrite solution to obtain a turbid liquid. An aqueous 6-aminonaphthalene-2-sulfonic acid solution was added to this turbid solution, and the resulting triazole was salted out with sodium chloride to obtain an exemplary compound 50 represented by the following structure.

<PH buffering ability of coloring material>
Example Compound 16 and Example Compound 50 obtained above, and C.I. I. Direct Yellow 132 and C.I. I. Using each color material of Direct Yellow 86, 20 mL of a 50 mmol / L aqueous solution of the color material was prepared. When pH was measured about each obtained aqueous solution, exemplary compound 16 is 7.58, exemplary compound 50 is 7.48, C.I. I. Direct Yellow 132 is 7.50 and C.I. I. Direct Yellow 86 was 8.30. Thereafter, a 2.8 N aqueous nitric acid solution was dropped little by little into each aqueous solution, the pH of the aqueous solution was measured as needed, and the amount of the aqueous nitric acid solution added when the pH of the aqueous solution reached 7.0 was determined. As a result, Exemplified Compound 16 was 35 μL, C.I. I. Direct Yellow 86 reached pH 7.0 when 40 μL of aqueous nitric acid solution was dropped. In addition, Exemplified Compound 50 and C.I. I. When a very small amount (10 μL or less) of an aqueous nitric acid solution was dropped in direct yellow 132, the pH of the aqueous solution became 4.0 or less. From the above results, Exemplified Compound 16 and C.I. I. Direct yellow 86 was found to be a color material having a pH buffering ability. The pH was measured at 25 ° C. using a pH meter F-21 (Horiba Seisakusho).

<Preparation of ink>
Example compounds 2, 3, 5, 6, 7, 16, and 50, which are yellow color materials obtained above, and C.I. I. Direct Yellow 132 and C.I. I. Each ink was prepared using Direct Yellow 86 as follows. First, each component shown in the following Table 4 and Table 5 was mixed and sufficiently stirred. Thereafter, pressure filtration was performed with a filter having a pore size of 0.2 μm to prepare yellow inks of Examples 1 to 17 and Comparative Examples 1 to 17.

<Evaluation>
(1) Light resistance Each of the inks obtained above was mounted on an ink jet recording apparatus (trade name: PIXUS iP8600) using thermal energy. The recording conditions were a temperature of 23 ° C., a relative humidity of 55%, a recording density of 2,400 dpi × 1,200 dpi, and a discharge amount of 2.5 pL. Here, a recording medium used for producing a recorded material was produced as follows. First, a resin composition containing 70 parts by mass of low density polyethylene, 20 parts by mass of high density polyethylene, and 10 parts by mass of titanium oxide is applied on both sides of a base paper having a basis weight of 155 g / m ² so as to be 25 g / m ^2. As a result, a support coated with resin was produced. Then, an ink receiving layer mainly composed of alumina hydrate and polyvinyl alcohol was formed on the support. In this way, a gap type ink receiving layer was provided, and the JAPAN TAPPI paper pulp test method no. A recording medium having a surface pH of 5.0 after 3 minutes measured according to 49-1.

  An image with a recording duty of 50% was formed on the obtained recording medium, and the image was naturally dried for 24 hours at a temperature of 23 ° C. and a relative humidity of 55%. The optical density of the image portion of the recorded matter thus obtained was measured (referred to as “optical density before test”). Further, this recorded matter was exposed for 72 hours at an irradiation intensity of 100 kilolux, a bath temperature of 24 ° C., and a relative humidity of 60% using a super xenon tester (trade name: SX-75; manufactured by Suga Test Instruments). Thereafter, the optical density of the image portion of the recorded matter was measured (referred to as “optical density after test”). The optical density was measured using a spectrophotometer (Spectorolino; manufactured by Gretag Macbeth) under the conditions of light source: D50 and field of view: 2 °. From the obtained optical density values before the test and optical density values after the test, the residual ratio of the optical density was calculated based on the following formula, and the light resistance was evaluated. The criteria for light resistance are as follows. The evaluation results are shown in Table 6.

ＡＡ：光学濃度の残存率が９５％以上。
Ａ：光学濃度の残存率が９０％以上９５％未満。
Ｂ：光学濃度の残存率が８０％以上９０％未満。
Ｃ：光学濃度の残存率が８０％未満。

AA: The residual ratio of optical density is 95% or more.
A: The residual ratio of the optical density is 90% or more and less than 95%.
B: The residual ratio of the optical density is 80% or more and less than 90%.
C: The residual ratio of optical density is less than 80%.

(2) Color tone Each of the inks obtained above was mounted on an ink jet recording apparatus (trade name: PIXUS iP8600) using thermal energy. The recording conditions were a temperature of 23 ° C., a relative humidity of 55%, a recording density of 2,400 dpi × 1,200 dpi, and a discharge amount of 2.5 pL. An image with a recording duty of 60% was formed on the same recording medium as described above, and the image was naturally dried for 24 hours at a temperature of 23 ° C. and a relative humidity of 55%. With respect to the image portion of the recorded matter thus obtained, the hue angle was measured using a spectrophotometer (trade name: Spectrolino; manufactured by Gretag Macbeth) to evaluate the color tone.

The evaluation criteria for the color tone are as follows. The evaluation results are shown in Table 6.
A: The hue angle is 88 ° or more and 90 ° or less.
B: Hue angle is 85 ° or more and less than 88 °, or greater than 90 ° and 92 ° or less.
C: Hue angle is less than 85 ° or greater than 92 °.

(3) Storage stability Each ink obtained above is filled in an unused (empty) BCI-7e ink cartridge (manufactured by Canon), and an ink supply port is provided so that the ink in the ink cartridge does not evaporate. Closed. The obtained ink cartridge was put in a sealed container and stored in a thermostatic bath at a temperature of 60 ° C. for 3 months. Thereafter, the ink cartridge was taken out from the thermostat and mounted on a head cartridge of an ink jet recording apparatus (trade name: PIXUS iP8600). Thereafter, the head cartridge was removed from the ink jet recording apparatus, and stored for 2 weeks at a temperature of 35 ° C. and a humidity of 10% with the ejection opening exposed. After that, the head cartridge was again mounted on the same ink jet recording apparatus as described above, and suction was performed a predetermined number of times, and the recovery property was confirmed to evaluate the storage stability of the ink. The suction means “print head cleaning” which is one of the functions provided in the ink jet recording apparatus (trade name: PIXUS iP8600).

The evaluation criteria for storage stability are as follows. The evaluation results are shown in Table 6.
A: Less than 4 times of suction, all discharge ports recover to a state where they can be discharged without any problem.
B: By 5 or 6 times of suction, all the discharge ports are restored to a state where they can be discharged without any problem.
C: Even if suction is performed 6 times, there are some discharge ports that cannot be discharged.

It is a perspective view of an inkjet recording device. It is a perspective view of the mechanism part of an inkjet recording device. It is sectional drawing of an inkjet recording device. FIG. 6 is a perspective view illustrating a state where an ink cartridge is mounted on the head cartridge. It is a disassembled perspective view of a head cartridge. FIG. 6 is a front view showing a recording element substrate in the head cartridge.

Explanation of symbols

M2041: separation roller M2060: paper feed tray M2080: paper feed roller M3000: pinch roller holder M3030: paper guide flapper M3040: platen M3060: transport roller M3070: pinch roller M3110: paper discharge roller M3120: spur M3160: paper discharge tray M4000: Carriage M5000: Pump M5010: Cap E0002: LF motor E0014: Electric substrate H1000: Head cartridge H1001: Recording head H1100: First recording element substrate H1101: Second recording element substrate H1200: First plate H1201: Ink supply port H1300: Electric wiring board H1301: External signal input terminal H1400: Second plate H1500: Tank holder (cartridge holder)
H1501: Ink flow path H1600: Flow path forming member H1700: Filter H1800: Seal rubber H1900: Ink cartridge H2000: Yellow nozzle array H2100: Magenta nozzle array H2200: Cyan nozzle array H2300: Light cyan nozzle array H2400: Black nozzle array H2500: Green Nozzle row H2600: Light magenta nozzle row

Claims (9)

An ink-jet ink containing at least two colorants, a first colorant and a second colorant,
The first colorant is a compound represented by the following general formula (I):
An ink-jet ink, wherein the second color material is a color material having a pH buffering ability.

(In general formula (I), R ₁ , R ₂ , Y ₁ and Y ₂ are each independently a monovalent group, and X ₁ and X ₂ are each independently having a Hammett's σp value of 0.20 or more. Z ₁ and Z ₂ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group An aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and M is a hydrogen atom, an alkali metal, ammonium, or organic ammonium.) The inkjet ink according to claim 1, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (II).

(In General Formula (II), Y ₁ and Y ₂ are each independently a monovalent group, and X ₁ and X ₂ are each independently an electron-withdrawing group having a Hammett's σp value of 0.20 or more. And each M is independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.) The inkjet ink according to claim 1, wherein the second coloring material is a compound represented by the following general formula (III).

(In General Formula (III), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group, n is 1 or 2, and m is 1 to 3) X is an integer of 2 to 4, y is an integer of 1 to 3, and M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.) The inkjet ink according to claim 3, wherein the compound represented by the general formula (III) is a compound represented by the following general formula (IV).

(In the general formula (IV), R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a sulfonic acid group, n is 1 or 2, and l (el) is 1 or 2, x is an integer of 2 to 4, y is an integer of 1 to 3, and M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)   The content (mass%) of the first color material in the ink is 1.0 times or more and 5.0 by mass ratio with respect to the content (mass%) of the second color material in the ink. The inkjet ink according to any one of claims 1 to 4, wherein the inkjet ink is less than or equal to 2 times.   6. An ink jet recording method for recording on a recording medium by ejecting ink by an ink jet method, wherein the ink is the ink for ink jet according to any one of claims 1 to 5.   6. An ink cartridge comprising an ink container for containing ink, wherein the ink is the ink jet ink according to claim 1.   6. A recording unit comprising an ink storage portion for storing ink and a recording head for ejecting ink, wherein the ink is the ink jet ink according to claim 1. And recording unit.   6. An ink jet recording apparatus comprising an ink containing portion for containing ink and a recording head for ejecting ink, wherein the ink is the ink for ink jet according to any one of claims 1 to 5. An ink jet recording apparatus.

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