JP6132951B2 - Ink, ink cartridge, and ink jet recording method - Google Patents

Description

  The present invention relates to an ink, an ink cartridge, and an ink jet recording method.

  The ink jet recording method is a recording method in which an ink droplet is applied to a recording medium to form an image, and is rapidly spreading due to its low cost and an increase in recording speed. In general, the recorded matter obtained by the ink jet recording method has low image fastness as compared with a silver salt photograph. In particular, when the recorded material is exposed to environmental gases such as light, humidity, heat, or ozone gas present in the air for a long time, the color material of the recorded material deteriorates, and the color tone of the image or fading easily occurs. There are problems such as.

  The discoloration of an image recorded using an ink containing a black color material (black ink) is often accompanied by a change in color tone due to deterioration of the color material. Further, black ink is used for both monochrome images and full-color images, and in recent years, it has been demanded that an image having a high optical density can be recorded when not only glossy paper but also plain paper is used. Furthermore, in recent years, in order to extend the usable period of ink, it has been demanded that the ink can be used without any problem even after being stored for a long time, and the demand for the storage stability of the ink is increasing.

  For black color materials, polyazotization of molecular structure has been widely studied. For example, there are proposals regarding a tetrakisazo compound having an electron-withdrawing group and a tetrakisazo compound having three naphthalene rings (see Patent Documents 1 and 2).

International Publication No. 2006/051850 International Publication No. 2005/108502

  The present inventors have studied the color material disclosed in Patent Document 1 in order to improve the ozone resistance and color developability of an image. As a result, the inventors of the present invention have disclosed that some of the color materials disclosed in Patent Document 1 can stably discharge ink after storage, although the ozone resistance and color developability of the recorded image can satisfy a desired level. It has been found that another problem arises that the performance decreases.

  Accordingly, an object of the present invention is to provide an ink capable of recording an image having excellent ejection stability of an ink after storage, high optical density, and excellent ozone resistance. Another object of the present invention is to provide an ink cartridge and an ink jet recording method using the ink.

  The above object is achieved by the present invention described below. That is, according to the present invention, an inkjet ink containing a coloring material and an additive, wherein the coloring material includes a compound represented by the following general formula (I), and the additive is represented by the following general formula: An ink comprising at least one of a compound represented by the formula (II) and a compound represented by the following general formula (III) is provided.

（前記一般式（Ｉ）中、Ｒ₁及びＲ₃は、それぞれ独立に、水素原子、ハロゲン原子、シアノ基、ヒドロキシ基、カルボン酸基、スルホン酸基、ホスホン酸基、スルファモイル基、Ｎ−アルキルアミノスルホニル基、炭素数１乃至４のアルキルスルホニル基（ヒドロキシ基で置換されていてもよい）、ニトロ基、アシル基、ウレイド基、炭素数１乃至４のアルキル基（ヒドロキシ基又は炭素数１乃至４のアルコキシ基で置換されていてもよい）、炭素数１乃至４のアルコキシ基（アルキル部分は、ヒドロキシ基、炭素数１乃至４のアルコキシ基、スルホン酸基、又はカルボン酸基で置換されていてもよい）、アシルアミノ基、又はアルキルスルホニルアミノ基を表し、Ｒ₂は、水素原子、又はスルホン酸基を表し、ｎは、０又は１を表し、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を表す）

(In the general formula (I), R ₁ and R ₃ are each independently a hydrogen atom, halogen atom, cyano group, hydroxy group, carboxylic acid group, sulfonic acid group, phosphonic acid group, sulfamoyl group, N-alkyl. An aminosulfonyl group, an alkylsulfonyl group having 1 to 4 carbon atoms (which may be substituted with a hydroxy group), a nitro group, an acyl group, a ureido group, an alkyl group having 1 to 4 carbon atoms (a hydroxy group or 1 to carbon atoms) 4 may be substituted with an alkoxy group having 4 carbon atoms), an alkoxy group having 1 to 4 carbon atoms (the alkyl moiety is substituted with a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group). may be), an acylamino group, or an alkylsulfonyl amino group, R ₂ represents a hydrogen atom, or a sulfonic acid group, n is 0 or 1, M is Each independently represent a hydrogen atom, an alkali metal, ammonium, or organic ammonium)

（前記一般式（II）中、Ｒ₄は、水素原子、ハロゲン原子、シアノ基、ヒドロキシ基、カルボン酸基、スルホン酸基、ホスホン酸基、スルファモイル基、Ｎ−アルキルアミノスルホニル基、炭素数１乃至４のアルキルスルホニル基（ヒドロキシ基で置換されていてもよい）、ニトロ基、アシル基、ウレイド基、炭素数１乃至４のアルキル基（ヒドロキシ基又は炭素数１乃至４のアルコキシ基で置換されていてもよい）、炭素数１乃至４のアルコキシ基（アルキル部分は、ヒドロキシ基、炭素数１乃至４のアルコキシ基、スルホン酸基、又はカルボン酸基で置換されていてもよい）、アシルアミノ基、又はアルキルスルホニルアミノ基を表し、Ｒ₅は、水素原子、ヒドロキシ基、又はアミノ基を表し、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を表す）

(In the general formula (II), R ₄ is a hydrogen atom, halogen atom, cyano group, hydroxy group, carboxylic acid group, sulfonic acid group, phosphonic acid group, sulfamoyl group, N-alkylaminosulfonyl group, carbon number 1 1 to 4 alkylsulfonyl groups (which may be substituted with hydroxy groups), nitro groups, acyl groups, ureido groups, 1 to 4 alkyl groups (substituted with hydroxy groups or alkoxy groups having 1 to 4 carbon atoms) May be substituted), an alkoxy group having 1 to 4 carbon atoms (the alkyl portion may be substituted with a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group), an acylamino group , or an alkylsulfonylamino group, R ₅ represents a hydrogen atom, hydroxy group, or an amino group, M are each independently a hydrogen atom, an alkali Genus, ammonium, or an organic ammonium)

（前記一般式（III）中、Ｒ₆は、水素原子、ヒドロキシ基、又はアミノ基を表し、Ｒ₇は、水素原子、又はスルホン酸基を表し、Ｒ₈は、水素原子、ハロゲン原子、シアノ基、ヒドロキシ基、カルボン酸基、スルホン酸基、ホスホン酸基、スルファモイル基、Ｎ−アルキルアミノスルホニル基、炭素数１乃至４のアルキルスルホニル基（ヒドロキシ基で置換されていてもよい）、ニトロ基、アシル基、ウレイド基、炭素数１乃至４のアルキル基（ヒドロキシ基又は炭素数１乃至４のアルコキシ基で置換されていてもよい）、炭素数１乃至４のアルコキシ基（アルキル部分は、ヒドロキシ基、炭素数１乃至４のアルコキシ基、スルホン酸基、又はカルボン酸基で置換されていてもよい）、アシルアミノ基、又はアルキルスルホニルアミノ基を表し、ｎは、０又は１を表し、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を表す）

(In the general formula (III), R ₆ represents a hydrogen atom, a hydroxy group, or an amino group, R ₇ represents a hydrogen atom or a sulfonic acid group, and R ₈ represents a hydrogen atom, a halogen atom, or cyano. Group, hydroxy group, carboxylic acid group, sulfonic acid group, phosphonic acid group, sulfamoyl group, N-alkylaminosulfonyl group, alkylsulfonyl group having 1 to 4 carbon atoms (which may be substituted with hydroxy group), nitro group An acyl group, a ureido group, an alkyl group having 1 to 4 carbon atoms (which may be substituted with a hydroxy group or an alkoxy group having 1 to 4 carbon atoms), an alkoxy group having 1 to 4 carbon atoms (the alkyl moiety is a hydroxy group) Group, which may be substituted with an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group), an acylamino group, or an alkylsulfonylamino group. n represents 0 or 1, M represents independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium)

  According to the present invention, it is possible to provide an ink capable of recording an image having excellent optical discharge stability after storage, high optical density, and excellent ozone resistance. In addition, according to the present invention, it is possible to provide an ink cartridge and an ink jet recording method using this ink.

It is sectional drawing which shows typically one Embodiment of the ink cartridge of this invention. FIG. 2 is a diagram schematically illustrating an example of an ink jet recording apparatus used in the ink jet recording method of the present invention, in which (a) is a perspective view of a main part of the ink jet recording apparatus, and (b) is a perspective view of a head cartridge.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. 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. Ink jet ink may be simply referred to as “ink”.

  The molecular structure of the black color material and the optical density of the image are considered to have the following relationship. In general, an image with low light reflectance in the visible light region (approximately 380 nm or more and 830 nm or less) has a high optical density and is easily recognized. Further, as shown in the “standard photopic spectral luminous efficiency curve” defined by the CIE (International Commission on Illumination), the wavelength at which humans feel the brightest, that is, the optical density is low is around 555 nm. That is, in order to increase the optical density of an image, it is important to use a black color material having a low reflectance of light near 555 nm, that is, a high absorption characteristic near 555 nm, in the visible light region. The maximum absorption wavelength of the tetrakisazo compound having an electron-withdrawing group proposed in Patent Document 1 is around 570 nm. On the other hand, the maximum absorption wavelength of the tetrakisazo compound having three naphthalene rings proposed in Patent Document 2 is shifted to around 640 nm. For this reason, when the compound represented by the general formula (I) (tetrakisazo compound having an electron-withdrawing group) is used, an image having a higher optical density is recorded as compared with the case of using another tetrakisazo compound. It is considered possible.

  In a recording medium such as plain paper, the color material (dye) hardly stays in the vicinity of the surface of the recording medium, so that the optical density of the image tends to be low. For this reason, in order to improve the optical density of an image recorded on a recording medium such as plain paper, it is important to improve the color developability of the color material itself. In addition, in a recording medium such as glossy paper, the recorded image is often stored for a long period of time, so it is important to improve the ozone resistance of the image. If an ink containing a compound represented by the general formula (I), which is a black color material, is used, an image excellent in ozone resistance and optical density can be recorded. However, the present inventors examined the image recorded using the ink containing the compound represented by the general formula (I) and the reliability of the ink. As described above, the ink after storage It has been found that problems relating to the discharge stability occur. That is, it has been found that when the ink after storage is used, the ejection stability is lowered.

  Since the compound represented by the general formula (I) has high molecular planarity, the molecules are considered to easily aggregate. In addition, a compound having a sulfur atom generally exhibits a strong interaction with an aromatic ring rich in π electrons. Since the compound represented by the general formula (I) has at least three sulfonic acid groups, the interaction between molecules is strongly generated due to the sulfur atom, so that the molecule is sterically or orbitally energetic. It can be considered that they tend to aggregate together. For these reasons, when an ink containing the compound represented by the general formula (I) is stored for a long period of time, molecules are aggregated to form many cluster-like aggregates. Therefore, after being stored in an ink state for a long period of time, an aggregate of the compound represented by the general formula (I) accumulates in an ink flow path or a filter of the recording head. The present inventors consider that the ink ejection stability is lowered due to the influence of the aggregate.

  Under such circumstances, the present inventors have studied to improve the ejection stability of the ink containing the compound represented by the general formula (I) even after being stored for a long time. . First, a plurality of inks containing an additive of at least one of the compound represented by the general formula (II) and the compound represented by the general formula (III) are prepared, and each ink is placed in a thermostatic bath at a temperature of 80 ° C. Stored for 336 hours. This storage condition is an accelerated test assuming a period sufficiently exceeding the storage period of a general ink jet ink. And when the image was recorded using the ink after preservation | save, it turned out that the fall of discharge stability is suppressed. The inventors presume this reason as follows.

  The compound represented by the general formula (II) and the compound represented by the general formula (III) that can be used as an additive in the ink of the present invention are similar to the compound (coloring material) represented by the general formula (I). In addition to having a structure as described above, it is a compound having a lower molecular weight than a coloring material and having a sulfur atom. Therefore, the compound represented by the general formula (II) and the compound represented by the general formula (III) are excellent in affinity with the compound represented by the general formula (I) used as a coloring material, and the color thereof. It is presumed that aggregation of the molecules of the material is suppressed.

<Ink>
The inkjet ink of the present invention contains a color material and an additive. Hereinafter, the components constituting the ink of the present invention and the physical properties of the ink will be described in detail.

(Color material)
The ink of the present invention contains a color material (dye) containing a compound represented by the following general formula (I).

In general formula (I), R ₁ and R ₃ each independently represent a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, a sulfamoyl group, or an N-alkylaminosulfonyl group. Group, an alkylsulfonyl group having 1 to 4 carbon atoms (which may be substituted with a hydroxy group), a nitro group, an acyl group, a ureido group, an alkyl group having 1 to 4 carbon atoms (a hydroxy group or having 1 to 4 carbon atoms) May be substituted with an alkoxy group), an alkoxy group having 1 to 4 carbon atoms (the alkyl portion may be substituted with a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group) Good), an acylamino group, or an alkylsulfonylamino group.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  The number of carbon atoms of the alkyl moiety in the N-alkylaminosulfonyl group is preferably 1 to 4. Examples of the N-alkylaminosulfonyl group include N-methylaminosulfonyl group, N-ethylaminosulfonyl group, N- (n-butyl) aminosulfonyl group, N, N-dimethylaminosulfonyl group, N, N-di (n -Propyl) aminosulfonyl group and the like.

  The alkylsulfonyl group having 1 to 4 carbon atoms which may be substituted with a hydroxy group includes a substituted or unsubstituted alkylsulfonyl group having 1 to 4 carbon atoms. Examples of the alkylsulfonyl group include unsubstituted alkylsulfonyl groups such as methylsulfonyl, ethylsulfonyl, propylsulfonyl and butylsulfonyl; substituted alkylsulfonyl groups such as hydroxyethylsulfonyl and 2-hydroxypropylsulfonyl.

  The acyl group includes an aliphatic acyl group. The number of carbon atoms of the alkyl moiety in the acyl group is preferably 1 to 4. Examples of the acyl group include acetyl, propionyl, butyryl, isobutyryl and the like.

  The alkyl group having 1 to 4 carbon atoms which may be substituted with a hydroxy group or an alkoxy group having 1 to 4 carbon atoms includes a substituted or unsubstituted alkyl group and a linear or branched alkyl group. . Here, the carbon number in the alkyl group having 1 to 4 carbon atoms refers to the carbon number in the case of unsubstituted. Therefore, the alkyl group having 1 to 4 carbon atoms substituted by the alkoxy group having 1 to 4 carbon atoms may have more than 4 carbon atoms as a whole. Examples of the alkyl group include unsubstituted alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl; 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, Examples include substituted alkyl groups such as methoxyethyl, 2-ethoxyethyl, n-propoxyethyl, isopropoxyethyl, n-butoxyethyl, methoxypropyl, ethoxypropyl, n-propoxypropyl, isopropoxybutyl, and n-propoxybutyl. Can do.

  The alkoxy group having 1 to 4 carbon atoms includes a substituted or unsubstituted alkoxy group, and the alkyl part in the alkoxy group is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group. May be substituted. Here, the number of carbon atoms in the alkoxy group having 1 to 4 carbon atoms refers to the number of carbon atoms when unsubstituted. Therefore, the alkoxy group having 1 to 4 carbon atoms in which the alkyl group in the alkoxy group is substituted may have more than 4 carbon atoms as a whole. Examples of the alkoxy group include unsubstituted alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy; 2-hydroxyethoxy, 2-hydroxypropoxy, 3-hydroxypropoxy, methoxy Ethoxy, ethoxyethoxy, n-propoxyethoxy, isopropoxyethoxy, n-butoxyethoxy, methoxypropoxy, ethoxypropoxy, n-propoxypropoxy, isopropoxybutoxy, n-propoxybutoxy, 2-hydroxyethoxyethoxy, carboxymethoxy, 2- Examples thereof include substituted alkoxy groups such as carboxyethoxy, 3-carboxypropoxy, 3-sulfopropoxy and 4-sulfobutoxy.

  The acylamino group includes an aliphatic acylamino group. The number of carbon atoms of the alkyl moiety in the acylamino group is preferably 1 to 4. Examples of the acylamino group include acetylamino, propionylamino, butyrylamino, isobutyrylamino and the like.

  The alkylsulfonylamino group preferably has 1 to 4 carbon atoms. Examples of the alkylsulfonylamino group include methylsulfonylamino, ethylsulfonylamino, propylsulfonylamino and the like.

In general formula (I), R ₂ represents a hydrogen atom or a sulfonic acid group.

  In general formula (I), n represents 0 or 1. When n is 0, it means that the sulfonic acid group is not bonded to the corresponding position in the general formula (I) and a hydrogen atom is bonded instead.

  In general formula (I), M represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium each independently. Examples of the alkali metal include lithium, sodium, and potassium. Examples of organic ammonium include alkylamines having 1 to 3 carbon atoms such as methylamine and ethylamine; 1 to 4 carbon atoms such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine. The following mono-, di- or trialkanolamines can be mentioned. In the present invention, it is preferable that M in the general formula (I) is sodium.

  The carboxylic acid group, sulfonic acid group, and phosphonic acid group may be free acid type (H type) or salt type. When the carboxylic acid group or the like is in a salt form (when forming a salt), alkali metal, ammonium, and organic ammonium cations can be exemplified.

  The compound represented by the general formula (I) is preferably a compound represented by the following general formula (IV). Among the compounds represented by the general formula (I), the compound represented by the general formula (IV) has high solubility. For this reason, the compound represented by the general formula (IV) has a low aggregation property among the compounds represented by the general formula (I), and can particularly effectively suppress a decrease in ejection stability after storage.

  In general formula (IV), M represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium each independently. Specific examples of M in general formula (IV) are the same as the specific examples of M in general formula (I) described above.

  When preferred examples of the compound represented by the general formula (I) are represented in the free acid form, the exemplified compounds 1 to 7 shown below can be exemplified. Of course, in the present invention, the compound represented by the general formula (I) is not limited to the exemplified compounds shown below as long as it is included in the structure of the general formula (I) and the definition thereof. In the present invention, among the exemplary compounds shown below, exemplary compounds 1 and 3 are more preferable, and exemplary compound 1 is more preferable.

  The content X (% by mass) of the compound represented by the general formula (I) in the ink is preferably 0.10% by mass or more and 10.00% by mass or less based on the total mass of the ink. The content X is more preferably 0.50% by mass or more and 8.00% by mass or less, and further preferably 1.00% by mass or more and 6.00% by mass or less.

  In the ink of the present invention, as long as the object of the present invention is not impaired, as a coloring material, in addition to the compound represented by the general formula (I), another type of dye other than the compound represented by the general formula (I) Or pigments may be included.

(Additive)
The ink of the present invention contains an additive containing at least one of a compound represented by the following general formula (II) and a compound represented by the following general formula (III). The ink of the present invention contains the specific additive and the compound (coloring material) represented by the general formula (I). Therefore, even after the ink has been stored for a long period of time, the ink has excellent ejection stability, and the ink can record an image having high optical density and excellent ozone resistance.

In the general formula (II), R ₄ represents a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, a sulfamoyl group, an N-alkylaminosulfonyl group, or 1 to 4 carbon atoms. Alkylsulfonyl groups (which may be substituted with hydroxy groups), nitro groups, acyl groups, ureido groups, alkyl groups having 1 to 4 carbon atoms (substituted with hydroxy groups or alkoxy groups having 1 to 4 carbon atoms) Or an alkoxy group having 1 to 4 carbon atoms (the alkyl portion may be substituted with a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group), an acylamino group, or Represents an alkylsulfonylamino group. R ₅ represents a hydrogen atom, a hydroxy group, or an amino group. M represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium each independently.

In the general formula (III), R ₆ represents a hydrogen atom, hydroxy group, or amino group, R ₇ represents a hydrogen atom, or a sulfonic acid group. R ₈ represents a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, a sulfamoyl group, an N-alkylaminosulfonyl group, an alkylsulfonyl group having 1 to 4 carbon atoms (hydroxy group). A nitro group, an acyl group, a ureido group, an alkyl group having 1 to 4 carbon atoms (which may be substituted with a hydroxy group or an alkoxy group having 1 to 4 carbon atoms), 1 carbon atom Represents an alkoxy group of 1 to 4 (the alkyl moiety may be substituted with a hydroxy group, an alkoxy group of 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group), an acylamino group, or an alkylsulfonylamino group. n represents 0 or 1, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium.

Examples of R ₄ in the general formula (II) and R ₈ in the general formula (III) include the same groups as those exemplified as R ₁ and R ₃ in the general formula (I). R ₅ in the general formula (II) and R ₆ in the general formula (III) represent a hydrogen atom, a hydroxy group, or an amino group. Examples of R ₇ in the general formula (III) include the same groups as those exemplified as R ₂ in the general formula (I). Specific examples of M in the general formulas (II) and (III) are the same as the specific examples of M in the general formula (I).

  The compound represented by the general formula (II) is preferably a compound represented by the following general formula (V). Moreover, it is preferable that the compound represented by general formula (III) is a compound represented by the following general formula (VI).

In general formula (V), R ₅ represents a hydrogen atom, a hydroxy group, or an amino group, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium. Specific examples of M in the general formula (V) are the same as the specific examples of M in the general formula (II). R ₅ is preferably a hydrogen atom or an amino group.

In general formula (VI), R ₆ represents a hydrogen atom, a hydroxy group, or an amino group, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium. Specific examples of M in the general formula (VI) are the same as the specific examples of M in the general formula (III). R ₆ is preferably a hydrogen atom or an amino group.

The ink preferably contains both the compound represented by the general formula (II) and the compound represented by the general formula (III) as an additive, the compound represented by the general formula (V), and It is more preferable to contain both compounds represented by the general formula (VI). In this case, it is particularly preferable that R ₅ in the compound represented by the general formula (V) and R ₆ in the compound represented by the general formula (VI) are combinations shown below.
(I) R ₅ in the compound represented by the general formula (V) is a hydrogen atom, and R ₆ in the compound represented by the general formula (VI) is an amino group.
(Ii) R ₅ in the compound represented by the general formula (V) is an amino group, and R ₆ in the compound represented by the general formula (VI) is a hydrogen atom.

  The content Y (% by mass) of the additive in the ink is preferably 0.001% by mass or more and 2.00% by mass or less based on the total mass of the ink. The content Y is more preferably 0.004% by mass to 1.00% by mass, further preferably 0.005% by mass to 0.80% by mass, and particularly preferably 0.02% by mass to 0.50%. It is below mass%. In addition, when using both the compound represented by general formula (II) and the compound represented by general formula (III) as an additive, let these total be content Y.

  The content Y (mass%) of the additive (the total of each compound represented by the general formulas (II) and (III)) is the content X (the compound represented by the general formula (I)) of the content X ( The mass ratio (Y / X) to (mass%) is preferably 0.0010 times or more and 0.1000 times or less. By this mass ratio (Y / X) being 0.0010 times or more, an effect of suppressing aggregation of the compound represented by the general formula (I) can be easily obtained, and discharge stability can be particularly improved. Become. On the other hand, when the mass ratio (Y / X) is 0.1000 times or less, sufficient ozone resistance can be obtained. The mass ratio (Y / X) is preferably 0.0008 times or more and 0.2000 times or less, more preferably 0.0010 times or more and 0.1000 times or less. When the mass ratio (Y / X) is less than 0.0010, the effect of suppressing aggregation of the compound represented by the general formula (I) is reduced, and the discharge stability may be lowered. On the other hand, when the mass ratio (Y / X) exceeds 0.1000 times, ozone resistance tends to decrease. As the additive content Y increases, it is presumed that the ozone resistance decreases due to the discoloration or coloring of the additive by ozone or the effect of suppressing excessive aggregation of the coloring material.

The compound represented by general formula (II) or general formula (V) is compoundable based on a well-known method. An example of a synthesis scheme is shown below. The active hydrogen of compound (a) is protected with tosyl chloride (tosyl group is expressed as “Ts”) to obtain compound (b). Further, the diazonium salt (d) is obtained by reacting the compound (c) with sodium nitrite in the presence of hydrochloric acid. And a compound (e) is obtained by making a compound (b) and a diazonium salt (d) react. The tosyl group is eliminated from the obtained compound (e) to obtain the target compound (f). Compounds in the synthesis scheme (a), (b), (c), (d) and R _4, R ₅ and M in (e) is, R ₄ in the general formula (II) or formula (V), R Synonymous with ₅ and M.

The compound represented by general formula (III) or general formula (VI) is compoundable based on a well-known method. An example of a synthesis scheme is shown below. The active hydrogen of compound (g) is protected with tosyl chloride (tosyl group is expressed as “Ts”) to obtain compound (h). Further, the diazonium salt (j) is obtained by reacting the compound (i) with sodium nitrite in the presence of hydrochloric acid. And a compound (k) is obtained by making a compound (h) and a diazonium salt (j) react. The tosyl group is eliminated from the obtained compound (k) to obtain the target compound (l). R ₆ , R ₇ , n and M in the compounds (g), (h), (i), (j), (k) and (l) in the synthesis scheme are represented by the general formula (III) or the general formula (VI And R ₆ , R ₇ , n and M have the same meanings.

  When preferred examples of the compound represented by the general formula (II) or the general formula (V) are represented by a free acid type, the following exemplified compounds 8 to 10 can be exemplified. Of course, in the present invention, the compounds represented by the general formula (II) and the general formula (V) are as follows as long as they are included in the structures of the general formula (II) and the general formula (V) and the definitions thereof. It is not limited to the exemplified compounds shown in In the present invention, exemplary compounds 8 and 9 are more preferable among the exemplary compounds shown below.

  When preferred examples of the compound represented by the general formula (III) or the general formula (VI) are represented by a free acid type, the following exemplified compounds 11 to 13 can be exemplified. Of course, in the present invention, the compounds represented by the general formula (III) or the general formula (VI) are as follows as long as they are included in the structure of the general formula (III) or the general formula (VI) and the definition thereof. It is not limited to the exemplified compounds shown in In the present invention, exemplary compounds 11 and 12 are more preferable among the exemplary compounds shown below.

(Additive verification method)
Whether or not the compound represented by the general formula (II) and the compound represented by the general formula (III) are contained in the ink is the following (1) using high performance liquid chromatography (HPLC). And the verification method of (2) can be applied.
(1) Peak retention time (2) M / Z (posi) of mass spectrum for the peak in (1)

The analysis conditions of high performance liquid chromatography are as follows. A liquid (ink) diluted about 1000 times with pure water is used as a measurement sample. Analysis by high performance liquid chromatography is performed under the following conditions, and the retention time of the peak is measured.
Column: Fire C18 (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: described in Table 1.

Moreover, about the peak obtained by said high performance liquid chromatography, a mass spectrum is measured on condition of the following, and M / Z detected most strongly is measured with respect to posi.
・ Ionization method: ESI
・ Capillary voltage: 3.5kV
-Desolvent gas: 300 ° C
-Ion source temperature: 120 ° C
-Detector: posi; 40V 200-1500amu / 0.9sec

  The measurement was performed on the exemplified compound 8 and the exemplified compound 12 under the method and conditions described above. As a result, the obtained retention time and the value of M / Z (posi) are shown in Table 2. For an unknown ink, measurement is performed under the same method and conditions as described above, and when the obtained measurement value corresponds to the value shown in Table 2, it can be determined that the compound used in the ink of the present invention is contained. .

(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. In the present invention, it is preferable to use an aqueous ink containing at least water as an aqueous medium. 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 If the content of the water-soluble organic solvent is out of the above range, a high level of ink ejection stability may not be obtained sufficiently.

(Other additives)
In addition to the components described above, surfactants, pH adjusters, rust inhibitors, antiseptics, antifungal agents, antioxidants, anti-reduction agents, evaporation accelerators, chelating agents, and water-solubility, if necessary You may contain various additives, such as resin.

(Ink physical properties)
In the present invention, the viscosity of the ink at 25 ° C. is preferably 1.0 mPa · s or more and 5.0 mPa · s or less, and more preferably 1.0 mPa · s or more and 3.5 mPa · s or less. The static surface tension of the ink at 25 ° C. is preferably 28 mN / m or more and 45 mN / m or less. Furthermore, the pH of the ink at 25 ° C. is preferably 5 or more and 9 or less.

<Ink cartridge>
The ink cartridge of the present invention includes ink and an ink storage unit that stores the ink. And the ink accommodated in this ink accommodating part is the ink of this invention demonstrated above. FIG. 1 is a cross-sectional view schematically showing an embodiment of the ink cartridge of the present invention. As shown in FIG. 1, an ink supply port 12 for supplying ink to the recording head is provided on the bottom surface of the ink cartridge. The inside of the ink cartridge is an ink storage portion for storing ink. The ink storage portion is composed of an ink storage chamber 14 and an absorber storage chamber 16, which communicate with each other via a communication port 18. The absorber housing chamber 16 communicates with the ink supply port 12. The ink storage chamber 14 stores liquid ink 20, and the absorber storage chamber 16 stores absorbers 22 and 24 that hold the ink in an impregnated state. The ink storage unit may have a form in which the entire amount of ink stored is held by an absorber without having an ink storage chamber for storing liquid ink. Further, the ink storage portion may have a form that does not have an absorber and stores the entire amount of ink in a liquid state. Further, the ink cartridge may be configured to have an ink storage portion and a recording head.

<Inkjet recording method>
The ink jet recording method of the present invention is a method of recording an image on a recording medium by discharging the ink of the present invention described above from an ink jet recording head. Examples of the method for ejecting ink include a method for imparting mechanical energy to the ink and a method for imparting thermal energy to the ink. In the present invention, it is particularly preferable to employ a system in which thermal energy is applied to the ink and ink is ejected. Other than using the ink of the present invention, the steps of the ink jet recording method may be known.

  2A and 2B are diagrams schematically showing an example of an ink jet recording apparatus used in the ink jet recording method of the present invention. FIG. 2A is a perspective view of a main part of the ink jet recording apparatus, and FIG. 2B is a perspective view of a head cartridge. It is. The ink jet recording apparatus is provided with a conveying means (not shown) for conveying the recording medium 32 and a carriage shaft 34. A head cartridge 36 can be mounted on the carriage shaft 34. The head cartridge 36 includes recording heads 38 and 40, and is configured such that an ink cartridge 42 is set. While the head cartridge 36 is conveyed along the carriage shaft 34 in the main scanning direction, ink (not shown) is ejected from the recording heads 38 and 40 toward the recording medium 32. Then, the recording medium 32 is conveyed in the sub-scanning direction by a conveying unit (not shown), whereby an image is recorded on the recording medium 32.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited at all by the following Example, unless the summary is exceeded. In addition, what is described as “parts” and “%” with respect to the component amounts is based on mass unless otherwise specified.

<Synthesis of coloring materials>
(Compound A)
With reference to the description in Patent Document 1, a compound represented by the following structural formula (1) was synthesized as a free acid form. Thereafter, ion exchange was performed according to a conventional method to obtain a sodium salt type compound (this compound is referred to as “compound A”).

(Compound B)
With reference to the description of Patent Document 1, a compound represented by the following structural formula (2) was synthesized as a free acid form. Thereafter, ion exchange was performed according to a conventional method to obtain a sodium salt type compound (this compound is referred to as “compound B”).

(Compound C)
With reference to the description in Patent Document 1, a compound represented by the following structural formula (3) was synthesized as a free acid form. Thereafter, ion exchange was performed according to a conventional method to obtain a sodium salt type compound (this compound is referred to as “compound C”).

(Compound D)
With reference to the description in Patent Document 2, a compound represented by the following structural formula (4) was synthesized as a free acid form. Thereafter, ion exchange was performed according to a conventional method to obtain a sodium salt type compound (this compound is referred to as “compound D”).

<Synthesis of additives>
(Compound E)
6.4 g of the following compound (a1) and 5.6 g of p-toluenesulfonyl chloride were reacted at pH 8 to 9 and a temperature of 80 ° C. for 3 hours. Thereafter, sodium chloride was added for salting out under acidic conditions, and the precipitate was collected by filtration to obtain 8.0 g of the following compound (b1). “Ts” represents a tosyl group.

  Next, 100 mL of water was added to 10 g of the following compound (c1), and further 10 mL of 12 mol / L hydrochloric acid was added, followed by cooling to a temperature of 0 ° C. Thereto, 3.0 g of 25% aqueous sodium nitrite solution was added dropwise to produce a diazonium salt. To this suspension containing the diazonium salt, an aqueous solution in which 8.0 g of the compound (b1) was dissolved in 72 mL of water was added, and the mixture was reacted for 12 hours while adjusting the temperature within the range of 0 to 20 ° C. At this time, the pH was adjusted to 7-9 with sodium carbonate. Then, it salted out with sodium chloride, the deposit was fractionated by filtration, and the monoazo compound 8.0g was obtained.

  The obtained monoazo compound was dissolved in 50 mL of water, adjusted to pH 10 or higher with sodium hydroxide, and reacted at a temperature of 70 ° C. for 1 hour. The pH was adjusted to 7-8 with 35% hydrochloric acid, salted out with sodium hydroxide, and the precipitated solid was collected by filtration. The obtained solid was dried to obtain Compound E. Compound E is shown in the following structure as the free acid form.

(Compound F)
Compound F was obtained in the same manner as in the synthesis of Compound E except that Compound (a1) was changed to the following Compound (a2). Compound F is represented by the following structure as a free acid form.

(Compound G)
Compound G was obtained in the same manner as the synthesis of Compound E, except that Compound (a1) was changed to the following Compound (a3). Compound G is represented by the following structure as a free acid form.

(Compound H)
6.4 g of the following compound (g1) and 5.6 g of p-toluenesulfonyl chloride were reacted at pH 8 to 9 and a temperature of 80 ° C. for 3 hours. Thereafter, sodium chloride was added for salting out under acidic conditions, and the precipitate was collected by filtration to obtain 8.0 g of the following compound (h1). “Ts” represents a tosyl group.

  100 mL of water was added to 10 g of aniline-4-sulfonic acid, 10 mL of 12 mol / L hydrochloric acid was further added, and the mixture was cooled to 0 ° C. Thereto, 3.0 g of 25% aqueous sodium nitrite solution was added dropwise to obtain a diazonium salt. An aqueous solution in which 8.0 g of aniline-2-sulfonic acid was dissolved in 72 mL of water was added to the suspension containing the obtained diazonium salt, and the mixture was reacted for 12 hours while adjusting the temperature within the range of 0 ° C to 20 ° C. At this time, the pH was adjusted to 7-9 with sodium carbonate. Then, it salted out with sodium chloride, the deposit was fractionated by filtration, and the following compound (i1) 8.0g was obtained.

  The obtained compound (i1) was dissolved in 50 mL of water, 10 mL of 12 mol / L hydrochloric acid was added, and the mixture was cooled to 0 ° C. Thereto, 3.0 g of 25% aqueous sodium nitrite solution was added dropwise to produce a diazonium salt. To this suspension containing the diazonium salt, an aqueous solution in which 5.0 g of the compound (h1) was dissolved in 50 mL of water was added and reacted for 12 hours while adjusting the temperature within the range of 0 ° C to 20 ° C. At this time, the pH was adjusted to 7-9 with sodium carbonate. Further, salting out was performed with sodium chloride, and the precipitate was collected by filtration to obtain a disazo compound.

  The obtained disazo compound was dissolved in 50 mL of water, adjusted to pH 10 or higher with sodium hydroxide, and reacted at a temperature of 70 ° C. for 1 hour. The pH was adjusted to 7-8 with 35% hydrochloric acid, salted out with sodium hydroxide, and the precipitate was collected by filtration. The obtained solid was dried to obtain Compound H. Compound H is shown in the following structure as the free acid form.

(Compound I)
Compound I was obtained in the same manner as the synthesis of Compound H except that Compound (g1) was changed to the following Compound (g2). Compound I is shown in the following structure as the free acid form.

(Compound J)
Compound J was obtained in the same manner as the synthesis of Compound H except that Compound (g1) was changed to the following Compound (g3). Compound J is represented by the following structure as a free acid form.

<Preparation of ink>
Each component (unit:%) shown in the upper part of Table 3 was mixed and sufficiently stirred, and then each ink was prepared by pressure filtration with a filter having a pore size of 0.20 μm. “Acetylenol E100” (manufactured by Kawaken Fine Chemical Co., Ltd.) in Table 3 is a trade name of a nonionic surfactant. The “remaining amount” in the column of ion-exchanged water in Table 3 means the remaining amount that makes the total amount of each component of ink 100.00%. In the lower part of Table 3, the content X (%) of the color material (compound represented by the general formula (I)) in the ink, additive (compound represented by the general formulas (II) and (III)) Content Y (%), Y / X values are shown.

<Evaluation>
Each ink obtained above was filled in an ink cartridge and mounted on an ink jet recording apparatus (trade name “PIXUS iP8600”, manufactured by Canon Inc.) that discharges ink from the recording head by the action of thermal energy. In this embodiment, a solid image recorded by applying 2.5 pL of ink to a unit area of 1/2400 inch and 1/1200 inch is defined as “recording duty is 100%”. When evaluating the optical density and ozone resistance, the optical density was measured using a spectrophotometer (trade name “Spectrolino”, manufactured by Gretag Macbeth) under the conditions of a light source: D50 and a visual field: 2 ·. In the present invention, according to the evaluation criteria for the following items, “C” is an unacceptable level and (“AA”) “A” and “B” are acceptable levels. The evaluation results are shown in Table 4.

(Optical density)
Using the above inkjet recording apparatus, a solid image having a recording duty of 100% is recorded on a recording medium (plain paper, trade name “PB PAPER”, manufactured by Canon) in an environment of a temperature of 23 ° C. and a relative humidity of 55%. did. The optical density of the solid image in the obtained recorded matter was measured. From the obtained optical density value, the optical density was evaluated according to the following evaluation criteria.
A: The optical density was 1.30 or more.
B: The optical density was 1.15 or more and less than 1.30.
C: The optical density was less than 1.15.

(Ozone resistance)
Using the above inkjet recording apparatus, the recording duty is 50% on a recording medium (glossy paper, product name “Canon Photo Paper / Glossy Gold”, manufactured by Canon) in an environment of a temperature of 23 ° C. and a relative humidity of 55%. A solid image was recorded. The optical density of the solid image in the obtained recorded matter was measured (optical density before the ozone resistance test). This recorded matter was placed in an ozone tester (trade name “OMS-H”, manufactured by Suga Test Instruments Co., Ltd.), and ozone exposure was performed for 24 hours at a bath temperature of 23 ° C., a relative humidity of 50% and an ozone gas concentration of 10 ppm. Thereafter, the optical density of the solid image in the recorded material was measured (optical density after the ozone resistance test). From the obtained optical density before the ozone resistance test and optical density value after the ozone resistance test, the residual ratio of the optical density = the optical density after the ozone resistance test / the optical density before the ozone resistance test / 100% The ozone resistance was evaluated according to the following evaluation criteria. In addition, the value calculated about the black component measured using the said spectrophotometer was used for the residual ratio of optical density for evaluation.
A: The residual ratio of the optical density was 60% or more.
B: The residual ratio of the optical density was less than 60%.

(Discharge stability)
Each ink was stored in a constant temperature bath at a temperature of 80 ° C. for 336 hours. Thereafter, the ink was filled in the ink cartridge and mounted on the head cartridge of the ink jet recording apparatus. Arbitrary A4 size solid images with recording duty of 150%, 100% and 50% on recording media (plain paper, trade name “PB PAPER”, manufactured by Canon) in an environment of temperature 23 ° C. and relative humidity 55% Was continuously recorded. The obtained image was visually evaluated according to the following evaluation criteria. The higher the solid image recording duty, the greater the amount of ink discharged. Therefore, if agglomerates occur, the agglomerates tend to accumulate in the ink flow path and filter of the recording head, and the ejection stability tends to decrease. Become. Therefore, this evaluation shows that the occurrence of aggregates is suppressed and discharge stability is excellent if no solid discharge occurs even when a solid image with a high recording duty is recorded.
AA: There was no ejection failure even when recording was performed at a duty of 150%.
A: There was no ejection failure even when printing was performed at 100% duty.
B: Slight non-ejection was confirmed when recording at 100% duty, but there was no non-ejection when recording at 50% duty.
C: Non-ejection was confirmed when recording with 50% duty.

  The ejection stability of Examples 1, 17, and 18 was all ranked A, but Examples 17 and 18 were relatively better than Example 1.

Claims (8)

An ink jet ink containing a coloring material and an additive,
The colorant contains a compound represented by the following general formula (I):
An ink characterized in that the additive contains at least one of a compound represented by the following general formula (II) and a compound represented by the following general formula (III).

(In the general formula (I), R ₁ and R ₃ are each independently a hydrogen atom, halogen atom, cyano group, hydroxy group, carboxylic acid group, sulfonic acid group, phosphonic acid group, sulfamoyl group, N-alkyl. An aminosulfonyl group, an alkylsulfonyl group having 1 to 4 carbon atoms (which may be substituted with a hydroxy group), a nitro group, an acyl group, a ureido group, an alkyl group having 1 to 4 carbon atoms (a hydroxy group or 1 to carbon atoms) 4 may be substituted with an alkoxy group having 4 carbon atoms), an alkoxy group having 1 to 4 carbon atoms (the alkyl moiety is substituted with a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group). may be), an acylamino group, or an alkylsulfonyl amino group, R ₂ represents a hydrogen atom, or a sulfonic acid group, n is 0 or 1, M is Each independently represent a hydrogen atom, an alkali metal, ammonium, or organic ammonium)

(In the general formula (II), R ₄ is a hydrogen atom, halogen atom, cyano group, hydroxy group, carboxylic acid group, sulfonic acid group, phosphonic acid group, sulfamoyl group, N-alkylaminosulfonyl group, carbon number 1 1 to 4 alkylsulfonyl groups (which may be substituted with hydroxy groups), nitro groups, acyl groups, ureido groups, 1 to 4 alkyl groups (substituted with hydroxy groups or alkoxy groups having 1 to 4 carbon atoms) May be substituted), an alkoxy group having 1 to 4 carbon atoms (the alkyl portion may be substituted with a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group), an acylamino group , or an alkylsulfonylamino group, R ₅ represents a hydrogen atom, hydroxy group, or an amino group, M are each independently a hydrogen atom, an alkali Genus, ammonium, or an organic ammonium)

(In the general formula (III), R ₆ represents a hydrogen atom, a hydroxy group, or an amino group, R ₇ represents a hydrogen atom or a sulfonic acid group, and R ₈ represents a hydrogen atom, a halogen atom, or cyano. Group, hydroxy group, carboxylic acid group, sulfonic acid group, phosphonic acid group, sulfamoyl group, N-alkylaminosulfonyl group, alkylsulfonyl group having 1 to 4 carbon atoms (which may be substituted with hydroxy group), nitro group An acyl group, a ureido group, an alkyl group having 1 to 4 carbon atoms (which may be substituted with a hydroxy group or an alkoxy group having 1 to 4 carbon atoms), an alkoxy group having 1 to 4 carbon atoms (the alkyl moiety is a hydroxy group) Group, which may be substituted with an alkoxy group having 1 to 4 carbon atoms, a sulfonic acid group, or a carboxylic acid group), an acylamino group, or an alkylsulfonylamino group. n represents 0 or 1, M represents independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium) The ink according to claim 1, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (IV).

(In the general formula (IV), each M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium) The compound represented by the general formula (II) is a compound represented by the following general formula (V), and the compound represented by the general formula (III) is represented by the following general formula (VI). The ink according to claim 1, which is a compound.

(In the general formula (V), R ₅ represents a hydrogen atom, a hydroxy group, or an amino group, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium)

(In the general formula (VI), R ₆ represents a hydrogen atom, a hydroxy group, or an amino group, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium)   The ink according to any one of claims 1 to 3, wherein the additive includes the compound represented by the general formula (II) and the compound represented by the general formula (III). R ₅ in the compound represented by the general formula (V) is a hydrogen atom, and R ₆ in the compound represented by the general formula (VI) is an amino group, or in the general formula (V) The ink according to claim 3 or 4, wherein R ₅ in the represented compound is an amino group, and R ₆ in the compound represented by the general formula (VI) is a hydrogen atom.   The content Y (mass%) of the additive is 0.0010 times or more and 0.1000 times or less as a mass ratio (Y / X) to the content X (mass%) of the coloring material. The ink according to any one of 5. An ink cartridge comprising ink and an ink containing portion for containing the ink,
The ink cartridge according to claim 1, wherein the ink is an ink according to claim 1. An inkjet recording method for recording an image on a recording medium by discharging ink from an inkjet recording head,
An ink jet recording method, wherein the ink is the ink according to any one of claims 1 to 6.

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