JP2018090736A - Ink set and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set which comprises an ink capable of recording an image having excellent color development, light resistance and moisture resistance and recording a secondary color image having excellent color development (particularly, a color reproduction range of a dark part) and suppressing strike-through.SOLUTION: There is provided an ink set having a combination of a first ink and a second ink. The first ink contains a self-dispersible pigment in which an ionic group is chemically bonded to a particle surface of a pigment directly or through other atomic group and the second ink contains a compound represented by the general formula (1) (at least one of R, R, Rand Ris an alkyl group having 5 to 7 carbon atoms and is a sulfonic acid group or a sulfamoyl group.)SELECTED DRAWING: None

Description

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

  In recent years, inkjet recording methods are required to be able to record images with higher image quality and longer storage than ever. In particular, for images recorded using color inks, it is particularly necessary to improve color developability and light resistance. In order to satisfy such requirements, ink dyes capable of recording images with improved color development and light resistance have been proposed. For example, a magenta ink for inkjet that can record an image with improved color developability, light resistance, and moisture resistance using a xanthene colorant having a specific structure has been proposed (see Patent Documents 1 and 2). .

  In addition, for black ink capable of recording an image excellent in optical density and fastness, it has been widely studied in recent years to use a self-dispersing pigment as a coloring material. For example, in order to record an image with improved optical density, a water-based ink containing self-dispersing carbon black and a specific salt has been proposed (Patent Document 3). In addition, an ink containing a self-dispersing pigment in which a functional group having high reactivity with calcium is bonded based on a calcium index that is an index of reactivity with calcium has been proposed (see Patent Document 4). Furthermore, an ink set composed of an ink containing a xanthene dye and an ink containing a self-dispersing pigment has been proposed in order to expand the color gamut reproduction range in the dark part (see Patent Document 5).

Japanese Patent Laid-Open No. 2006-108545 Japanese Patent Laying-Open No. 2006-102186 JP 2000-198955 A Special table 2009-515007 JP2012-193308A

  In recent years, it has been required to achieve a higher level of performance than ever for images obtained by the ink jet recording method. As a result of the study by the present inventors, it was found that by using the magenta ink containing the color material described in Patent Documents 1 and 2, it is possible to record an image having good color developability, light resistance, and moisture resistance. It was. In addition, by using these magenta inks and black inks containing self-dispersing pigments described in Patent Documents 3 and 4, it is possible to record a secondary color image having a good color reproduction range in the dark part. all right.

  However, when a secondary color image is recorded on a recording medium such as plain paper using the magenta ink and the black ink in combination, the phenomenon that the magenta ink comes off on the back surface (non-recording surface), that is, the back-through occurs. I understood.

  Accordingly, an object of the present invention is to provide an ink set including an ink capable of recording an image having excellent color developability, light resistance, and moisture resistance. It is another object of the present invention to provide an ink set that can record a secondary color image that is excellent in color developability (particularly, the color reproduction range of a dark portion) and in which the show-through is suppressed. Another object of the present invention is to provide an ink jet recording method using the ink set.

  The above object is achieved by the present invention described below. In other words, the ink set according to the present invention is an ink set having a combination of the first ink and the second ink, and the first ink has an ionic group directly on the particle surface of the pigment or through another atomic group. And the second ink contains a compound represented by the following general formula (1).

(In the general formula (1), R ₁ , R ₅ , R ₆ and R ₁₀ each independently represents an alkyl group. R ₃ and R ₈ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, aryloxy. R ₂ , R ₄ , R ₇ and R ₉ each independently represents a hydrogen atom, an ionic group, or a group represented by the following general formula (2), R ₂ , At least one of R ₄ , R ₇ and R ₉ represents a group represented by the following general formula (2): Z independently represents a sulfonic acid group or a sulfamoyl group, and R ₂ , R ₃ , R ₄ , at least one of R ₇ , R ₈ and R ₉ has an ionic group, n represents an integer of 0 to 6, and R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ are When there is no ionic group, n represents an integer of 1 to 6, and Z is present In some cases, the aromatic ring in the general formula (1) is substituted at the position of at least one hydrogen atom.)

(In General Formula (2), R ₁₁ represents an alkyl group having 5 to 7 carbon atoms.)

  ADVANTAGE OF THE INVENTION According to this invention, the ink set containing the ink which can record the image excellent in coloring property, light resistance, and moisture resistance can be provided. Furthermore, it is possible to provide an ink set that can record a secondary color image that is excellent in color developability (particularly, the color reproduction range of a dark portion) and in which the show-through is suppressed. Moreover, according to another embodiment of the present invention, an ink cartridge, an ink jet recording method, and an ink jet recording apparatus using the ink set can be provided. Moreover, according to the present invention, an ink jet recording method using this ink set can be provided.

The chart which shows the result of ¹ H NMR analysis of the exemplary compound 1. The chart which shows the result of ¹ H NMR analysis of the exemplary compound 5. The chart which shows the result of ¹ H NMR analysis of the exemplary compound 6. The chart which shows the result of ¹ H NMR analysis of the exemplary compound 15. The chart which shows the result of UV / Vis spectral analysis (in water, temperature 25 degreeC) of various compounds. 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 it is expressed as “contains a salt” for convenience. Ink jet ink may be simply referred to as “ink”. The physical property values are values at normal temperature (25 ° C.) unless otherwise specified.

  The present inventors have developed color development, light resistance, and moisture resistance of an image recorded with magenta ink, and color development of a secondary color image recorded using both black ink and magenta ink (color reproduction range of dark part). ) And the configuration of the ink set that improves. C. I. An image recorded with an ink containing Acid Red 289 as a colorant has a relatively low light resistance. Therefore, specifically, C.I. I. With regard to the color material capable of recording an image having the same color developability as that using Acid Red 289 and capable of recording an image with improved light resistance and moisture resistance, the color materials described in Patent Documents 1 and 2 are mainly used. Study was carried out. As a result, according to the ink containing a specific one of these coloring materials (compound represented by the general formula (1) described later), an image having both color developability, light resistance, and moisture resistance is recorded. I knew I would get it.

  Further, the inventors of the present invention also used a magenta ink containing a colorant that can achieve both of these characteristics and a black ink containing a self-dispersing pigment in combination with a secondary color image recorded on plain paper. The color reproduction range of was confirmed. As a result, it was found that by using the above ink set, the color reproduction range in the dark part was expanded and the color developability was also improved. However, it has been found that, depending on the type of plain paper, the back side of the secondary color image has a magenta ink breakthrough.

  The present inventors infer the reason why the strikethrough occurs as follows. The compound represented by the general formula (1) used in the present invention is C.I. I. The acid red 289 is used as a base to improve the moisture resistance of recorded images by increasing hydrophobicity. Therefore, the compound represented by the general formula (1) is C.I. I. Compared to Acid Red 289, it has a highly hydrophobic site. On the other hand, the compound represented by the general formula (1) is a dye, and also has a highly hydrophilic portion as Z in order to impart hydrophilicity to the compound. In the compound represented by the general formula (1), the coloring material acts like a surfactant depending on the positional relationship and the number of hydrophobic and hydrophilic portions. As a result, in a recording medium such as plain paper, the color material tends to penetrate easily. In particular, since the color material is particularly likely to permeate in a portion where the total amount of ink applied, such as a secondary color image, is large, it is considered that show-through occurs in the secondary color image.

  The ink set of the present invention includes a first ink containing a self-dispersing pigment in which an ionic group is chemically bonded to the pigment particle surface directly or via another atomic group, and a general formula (1) described later. A combination of the second ink containing a compound represented by the formula: According to the ink set having such a configuration, the show-through in the secondary color image can be effectively suppressed. The inventors presume the reason as follows.

When an ink containing a self-dispersing pigment is applied to a recording medium such as plain paper, the liquid component in the ink and the pigment are separated into solid and liquid, and the pigment starts to aggregate, so that the surface of the recording medium and its vicinity Pigment particles are fixed on the surface. Here, the self-dispersed pigment that is a dispersion method that does not use a resin dispersant has a higher proportion of the pigment particle surface exposed than the resin dispersion pigment that is a dispersion method that uses a resin dispersant. Then, the compound represented by the general formula (1) _as at least one of R _2, R 4, _{R 7} and _{R 9,} having a group represented by the general formula (2). Since the group represented by the general formula (2) has a long-chain alkyl group and has high hydrophobicity, the group interacts with the pigment particle surface in a hydrophobic manner to suppress permeation. As a result, it is considered that the strike through of the compound represented by the general formula (1) is suppressed.

<Ink set>
The ink set of the present invention has a combination of a first ink and a second ink. The ink set of the present invention may further include ink other than the first ink and the second ink. The ink set of the present invention is particularly suitable as an ink set for inkjet. As the form of the ink set of the present invention, (i) a set of a plurality of ink cartridges containing each ink independently, and (ii) a plurality of ink containing parts containing each ink independently are combined and integrated. There are ink cartridges and the like. However, the ink set of the present invention is not limited to the above forms (i) and (ii) as long as the ink set can be used in combination with the first ink and the second ink. Hereinafter, the components contained in the first ink (black ink) and the second ink (magenta ink) constituting the ink set of the present invention, the physical properties of the ink, and the like will be described in detail.

(Color material)
[Color material of the first ink: self-dispersing pigment]
The first ink constituting the ink set of the present invention contains, as a coloring material, a self-dispersing pigment in which an ionic group is chemically bonded to the pigment particle surface directly or via another atomic group. By using the self-dispersing pigment as the color material, it is not necessary to add a dispersant for dispersing the color material in the first ink, or the amount of the dispersant added can be reduced. Examples of the pigment type of the self-dispersing pigment include organic pigments and inorganic pigments such as carbon black, and any of those usable for ink jet inks can be used. In addition to the self-dispersing pigment, a dye or the like may be used in combination for purposes such as toning. The first ink is preferably a black ink using carbon black as a pigment. The content (mass%) of the pigment in the first ink is preferably 0.10 mass% or more and 15.00 mass% or less, based on the total mass of the first ink, and is 1.00 mass% or more and 10. More preferably, it is 00 mass% or less.

  Examples of the ionic group chemically bonded to the pigment particle surface directly or through another atomic group include anionic groups such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. Is mentioned. These anionic groups may form a salt. The anionic group may be either partially dissociated or completely dissociated. Examples of counter ions that form salts include alkali metals such as lithium, sodium, and potassium; unsubstituted ammonium; and cations such as organic ammonium. As other atomic groups (—R—), straight chain or branched alkylene groups having 1 to 12 carbon atoms, arylene groups such as phenylene groups and naphthylene groups, amide groups, sulfonyl groups, imino groups, and imino groups. , Carbonyl group, ester group, ether group and the like. Moreover, the group etc. which combined these groups are mentioned.

[Coloring material of second ink: compound represented by general formula (1)]
The second ink constituting the ink set of the present invention contains a compound represented by the following general formula (1) as a coloring material (dye). The content (% by mass) of the compound represented by the general formula (1) in the second ink is preferably 0.10% by mass or more and 10.00% by mass or less based on the total mass of the ink. More preferably, it is 10 mass% or more and 5.00 mass% or less. If the content of the compound represented by the general formula (1) is less than 0.10% by mass, the color developability and light resistance of the image may be insufficient. On the other hand, if the content of the compound represented by the general formula (1) exceeds 10.00% by mass, characteristics such as ink sticking resistance may be insufficient.

(In the general formula (1), R ₁ , R ₅ , R ₆ and R ₁₀ each independently represents an alkyl group. R ₃ and R ₈ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, aryloxy. R ₂ , R ₄ , R ₇ and R ₉ each independently represents a hydrogen atom, an ionic group, or a group represented by the following general formula (2), R ₂ , At least one of R ₄ , R ₇ and R ₉ represents a group represented by the following general formula (2): Z independently represents a sulfonic acid group or a sulfamoyl group, and R ₂ , R ₃ , R ₄ , at least one of R ₇ , R ₈ and R ₉ has an ionic group, n represents an integer of 0 to 6, and R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ are When there is no ionic group, n represents an integer of 1 to 6, and Z is present In some cases, the aromatic ring in the general formula (1) is substituted at the position of at least one hydrogen atom.)

(In General Formula (2), R ₁₁ represents an alkyl group having 5 to 7 carbon atoms.)
In general formula (1), R ₁ , R ₅ , R ₆ and R ₁₀ each independently represents an alkyl group. Examples of the alkyl group for R ₁ , R ₅ , R _6, and R ₁₀ include linear or branched alkyl groups having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. The alkyl group of R ₁ , R ₅ , R ₆ and R ₁₀ has a substituent as long as the color developability, light resistance, moisture resistance and ozone resistance of the compound represented by the general formula (1) are not impaired. May be. Examples of such a substituent include a hydroxy group; an alkoxy group having 1 to 3 carbon atoms such as a methoxy group, an ethoxy group, and a propoxy group; a cyano group; a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom; Can be mentioned. Examples of the alkyl group represented by R ₁ , R ₅ , R ₆ and R ₁₀ include those having a substituent, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, unsubstituted alkyl groups such as sec-butyl group, tert-butyl group, 1-methylbutyl group, n-pentyl group, n-hexyl group; 2-hydroxyethyl group, 2-methoxyethyl group, 2-cyanoethyl group, trifluoro A substituted alkyl group such as a methyl group; In order to obtain more excellent color developability and moisture resistance, the alkyl group preferably has 1 to 6 carbon atoms. Furthermore, from the viewpoint of ease of synthesis, the alkyl group preferably has 1 to 3 carbon atoms, and particularly preferably a methyl group, an ethyl group, an n-propyl group, or an isopropyl group.

In general formula (1), R ₃ and R ₈ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, or an ionic group. The alkyl group, alkoxy group, and aryloxy group of R ₃ and R ₈ are substituents as long as the color developability, light resistance, moisture resistance, and ozone resistance of the compound represented by the general formula (1) are not impaired. You may have. Examples of such a substituent include an alkyl group having 1 to 3 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group; an aryl group having 6 to 12 carbon atoms such as a phenyl group and a naphthyl group; Aralkyl groups having 7 to 14 carbon atoms such as benzyl group, p-tolyl group, m-xylyl group, 2-phenethyl group, naphthylethyl group; hydroxy group; carbamoyl group; sulfamoyl group; methoxy group, ethoxy group, n-propoxy Group, alkoxy group having 1 to 3 carbon atoms such as isopropoxy group; cyano group; halogen atom such as fluorine atom, chlorine atom, bromine atom; ion such as carboxylic acid group, sulfonic acid group, phosphoric acid group, phosphonic acid group Sex groups; and the like.

Examples of the alkyl group for R ₃ and R ₈ include linear or branched alkyl groups having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. Examples of the alkyl group of R ₃ and R ₈ include those having a substituent, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert. -Unsubstituted alkyl group such as butyl group, 1-methylbutyl group, n-pentyl group, n-hexyl group; 2-hydroxyethyl group, 2-methoxyethyl group, 2-cyanoethyl group, trifluoromethyl group, 3-sulfo group And substituted alkyl groups such as a propyl group, a 4-sulfobutyl group, and a 4-carboxybutyl group. Since more excellent moisture resistance is obtained and the solubility in water is also improved, the alkyl group preferably has 1 to 3 carbon atoms when the ionic group is not substituted. When is substituted, it is preferably 4 to 6.

Examples of the alkoxy group of R ₃ and R ₈ include linear or branched alkoxy groups having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. Examples of the alkoxy group of R ₃ and R ₈ include those having a substituent, for example, unsubstituted alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group; a 2-methoxyethoxy group, 2 -Substituted alkoxy groups such as hydroxyethoxy group and 3-carboxypropoxy group; The number of carbon atoms of the alkoxy group is preferably 1 to 6 because better moisture resistance can be obtained. Furthermore, it is particularly preferable that the alkoxy group has 1 to 3 carbon atoms, since it can provide better moisture resistance and also has good solubility in water.

Examples of the aryloxy group for R ₃ and R ₈ include aryloxy groups having 6 to 18 carbon atoms, preferably 6 to 12 carbon atoms, and particularly preferably 6 to 10 carbon atoms. Examples of the aryloxy group of R ₃ and R ₈ include those having a substituent, for example, a phenoxy group, a 2-naphthoxy group, a 1-anthryloxy group, a 9-phenanthryloxy group, and a 1-azurenyloxy group. Unsubstituted aryloxy groups such as p-methoxyphenoxy group, o-methoxyphenoxy group, o-tolyloxy group, p-tolyloxy group, 2,3-xylyloxy group, 3,5-xylyloxy group, 4-carboxy-2-yl And substituted aryloxy groups such as methylphenoxy group and 4-sulfo-2-methylphenoxy group. The number of carbon atoms of the aryloxy group is preferably 6 to 18, more preferably 6 to 12, and particularly preferably 6 to 10 in order to obtain better moisture resistance. Among these, a phenoxy group is preferable from the viewpoint of obtaining superior color developability and moisture resistance and ease of synthesis.

Examples of the ionic group of R ₃ and R ₈ include anionic groups such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. The ionic groups of R ₃ and R ₈ impart solubility to water to the compound represented by the general formula (1) together with ionic groups and sulfamoyl groups that may be present. The ionic group may be either acid type or salt type.

In the case of a salt-type ionic group, examples of counter ions that form a salt include alkali metals such as lithium, sodium, and potassium; unsubstituted ammonium; methylammonium, dimethylammonium, trimethylammonium, tetramethylammonium, and ethylammonium. Organic ammonium such as diethylammonium, triethylammonium, tetraethylammonium, n-propylammonium, isopropylammonium, diisopropylammonium, n-butylammonium, tetran-butylammonium, isobutylammonium, monoethanolammonium, diethanolammonium, triethanolammonium; Is mentioned. In addition to the ionic groups of R ₃ and R _8, other ionic groups that the compound represented by the general formula (1) may have either an acid type or a salt type. For example, as a counter ion in the case of a salt type ionic group, the same counter ions as those described above can be mentioned.

R ₃ and R ₈ are preferably an alkyl group having 1 to 3 carbon atoms in order to obtain better color developability and moisture resistance, and may be a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. More preferably it is. In particular, R ₃ and R ₈ are preferably an alkyl group having 1 to 3 carbon atoms, and R ₁₁ is preferably an alkyl group having 5 to 7 carbon atoms. From the viewpoint of ease of synthesis, when R ₃ and R ₈ have a substituent, it is preferable that all the groups have the same substituent.

In General Formula (1), R ₂ , R ₄ , R ₇ and R ₉ each independently represent a hydrogen atom, an ionic group, or a group represented by the following General Formula (2), and R ₂ , R ₄ , R ₇ and R ₉ represent a group represented by the following general formula (2). Since more excellent light resistance, moisture resistance, and ozone resistance can be obtained, the number of groups represented by the general formula (2) in the compound represented by the general formula (1) is 2 or more and 4 or less. Of which 2 is particularly preferable.

The compound represented by the general formula (1) of the present invention is C.I. I. Similar to Acid Red 289, it has higher light resistance and moisture resistance while having high magenta color developability. For this purpose, it is important that at least one of R ₂ , R ₄ , R ₇ and R ₉ is a group represented by the general formula (2).

Examples of the ionic group of R ₂ , R ₄ , R ₇ and R ₉ include anionic groups such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. The ionic groups of R ₂ , R ₄ , R ₇ and R ₉ impart water solubility to the compound represented by the general formula (1) together with ionic groups and sulfamoyl groups that may be present. . The ionic group may be either acid type or salt type. Examples of the counter ion that forms a salt in the case of a salt-type ionic group include those similar to those in the ionic groups of R ₃ and R ₈ described above.

The group represented by the general formula (2) of R ₂ , R ₄ , R ₇ and R ₉ is an acylamino group to which R ₁₁ (an alkyl group having 5 to 7 carbon atoms) is bonded. The number of carbon atoms of the alkyl group of R ₁₁ is required to be 5 to 7 in order to enhance color developability, moisture resistance, water solubility, and suppress secondary color image penetration. As the alkyl group for R ₁₁ , a linear or branched alkyl group is exemplified, and a linear alkyl group is preferable, and it is also preferable that the alkyl group has no substituent. Examples of the alkyl group for R ₁₁ include an n-pentyl group, an isopentyl group, a sec-pentyl group, a neopentyl group, a tert-pentyl group, an n-hexyl group, a sec-hexyl group, an n-heptyl group, and a sec-heptyl group. Etc. An n-pentyl group, a sec-pentyl group, a neopentyl group, and an n-heptyl group are particularly preferable from the viewpoints of obtaining superior moisture resistance and from the viewpoint of solubility in water and suppression of back-through of secondary color images.

From the viewpoint of ease of synthesis of the compound represented by the general formula (1), the following cases are preferable. When the compound represented by the general formula (1) has two or more groups represented by the general formula (2), it is preferable that the groups represented by the general formula (2) have the same structure. Moreover, it is preferable that both R ₂ and R ₇ are groups represented by the general formula (2). Each combination of _{R 1} and _R 6, _{R 2} and _R 7, _{R 3} and _R 8, _{R 4} and _R 9, _{R 5} and _{R 10} are preferably each the same group.

In general formula (1), Z represents a sulfonic acid group or a sulfamoyl group each independently. When at least one of R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ has an ionic group, n represents an integer of 0 to 6. When R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ do not have an ionic group, n represents an integer of 1 to 6. When Z is present, it is substituted at the position of at least one hydrogen atom of the aromatic ring in the general formula (1). Examples of ionic groups that R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ may have include a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group.

  The sulfonic acid group of Z gives water solubility to the compound represented by the general formula (1) together with other ionic groups and sulfamoyl groups that may be present. The sulfonic acid group may be either acid type or salt type. Examples of the counter ion that forms a salt in the case of a salt-type sulfonic acid group include the same as those in the above-described ionic groups.

  The sulfamoyl group of Z may have a substituent as long as the color developability, light resistance, moisture resistance, and ozone resistance of the compound represented by the general formula (1) are not impaired. Examples of such a substituent include an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a butyl group. Examples of the sulfamoyl group of Z include those having a substituent, for example, an unsubstituted sulfamoyl group (aminosulfonyl group); N-methylaminosulfonyl group, N, N-dimethylaminosulfonyl group, Nn-butyl. And a substituted sulfamoyl group substituted with an alkyl group having 1 to 4 carbon atoms such as an aminosulfonyl group.

n represents the number of substitutions of Z in the general formula (1). When at least one of R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ has an ionic group, n represents an integer of 0 to 6, and R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ do not have an ionic group, n represents an integer of 1 to 6. That is, when n = 0, the compound represented by the general formula (1) does not have a sulfonic acid group or sulfamoyl group as Z. In this case, in order to ensure the solubility of the compound as a dye in water, at least one of R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ needs to have an ionic group. On the other hand, when at least one of R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ has an ionic group, the compound can be dissolved in water by this ionic group. 0 may be sufficient.

  In order to increase the solubility in water, n is preferably 1 or more, and in order to improve moisture resistance, n is preferably 3 or less. In addition, the compound represented by General formula (1) may be a mixture of a plurality of compounds having different numbers of n. In the present invention, in the case of a mixture, n is expressed with a width. When it is a mixture, the median compound of the range is usually the most abundant. For example, a compound represented by n = 2-4 is a mixture including compounds of n = 2, 3, and 4, and the ratio of the compound of n = 3 is the largest.

  It is preferable that the compound represented by the general formula (1) has an ionic group, because more excellent light resistance can be obtained and solubility in water can be further increased. In this case, it is preferable that n in the general formula (1) is an integer of 1 to 6, and Z is a sulfonic acid group. In this case, the sulfonic acid group is in a salt form, and the counter ion of the sulfonic acid group is more preferably at least one selected from the group consisting of lithium ions, sodium ions, potassium ions, and ammonium ions.

The substitution position of Z in the main skeleton of the compound represented by the general formula (1) (that is, the structure in [] of the general formula (1)) is the substitution position of other substituents of the general formula (1), It is determined by the reaction conditions of sulfonation or chlorosulfonation. When all of R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ are substituents other than hydrogen atoms and the substituent of R ₁₁ does not have an aromatic hydrogen atom, Z is substituted at the hydrogen atom position. Further, when at least one of R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ is a hydrogen atom, Z may be substituted at the position of the hydrogen atom. In the present invention, from the viewpoint of ease of synthesis, it is preferable that Z is substituted at the hydrogen atom position of the xanthene skeleton.

The compound represented by the general formula (1) has tautomers. As the tautomer, in addition to the compound represented by the general formula (1), compounds represented by the following general formulas (1a) and (1b) can be considered. In the present invention, these compounds (tautomers) and salts are also included in the compound represented by the general formula (1). In addition, R < ₁ > -R < ₁₀ > in general formula (1a) and (1b) is synonymous with R < ₁ > -R < ₁₀ > in the said general formula (1).

The compound represented by the general formula (1) can be synthesized based on a known method. An example of a synthesis scheme is shown below. Compound in Synthesis Scheme (B), (C), (D) _R 1 in and (E) _{to R} 10, Z, n is in the _R 1 _{to R} 10, Z, in n synonymous formula (1) is there. In addition, the compound represented by the general formula (1) can be synthesized as a mixture of a plurality of isomers having different types, the number, and positions of substituents. However, for convenience, in the present invention, including a mixture, Described as “compound”.

  In the synthesis scheme exemplified above, the compound represented by the general formula (1) in which n = 0 is obtained through the first condensation step shown in the first step and the second condensation step shown in the second step. Synthesize. In addition to this, when further increasing the solubility of the compound in water, a sulfonation or sulfamoylation step may be added as the third stage, in which case n = 1 to 6 The compound represented by (1) is obtained.

  First, in the first condensation step, compound (C) is obtained by condensing compound (A) and compound (B) by heating in the presence of an organic solvent or a condensing agent. Next, in the second condensation step, the compound (D) and the compound (C) obtained in the first condensation step are heated and condensed to give the compound (E) (n = 0 in general) A compound represented by the formula (1) is obtained. In order to further increase the solubility of the compound in water, the compound (E) obtained in the second condensation step can be sulfonated using a sulfonating agent such as concentrated sulfuric acid or fuming sulfuric acid. Thereby, a compound (F) in which Z is a sulfonic acid group (a compound represented by the general formula (1) where n = 1 to 6) is obtained. In addition, the compound (E) obtained in the second condensation step is chlorosulfonated using chlorosulfonic acid or the like, and then reacted with an amine compound such as concentrated aqueous ammonia, alkylamine or arylamine to be sulfamoylated. Thus, a compound (F) in which Z is a sulfamoyl group (a compound represented by the general formula (1) where n = 1 to 6) is obtained.

  The organic solvent used in the condensation reaction of the synthesis scheme exemplified above will be described. In the first condensation step, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol and the like are preferably used alone or in combination. In the second condensation step, for example, ethylene glycol, N-methylpyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, chlorobenzene, dichlorobenzene, trichlorobenzene, nitrobenzene, etc. are used alone or in combination. And preferably used.

  The reaction temperature in the first condensation step is preferably 60 ° C. to 100 ° C., more preferably 70 ° C. or more and 90 ° C. or less. The reaction temperature in the second condensation step is preferably 120 ° C to 220 ° C, and more preferably 180 ° C or lower.

When synthesizing a compound in which R _{1 to} R ₅ and R _{6 to} R ₁₀ in the general formula (1) are the same group, the same kind as the compound (B) and the compound (D) in the above synthesis scheme is used. Things can be used. Therefore, in this case, the compound represented by the general formula (1) can be obtained by performing a one-step condensation process from the compound (A). The reaction temperature at that time is preferably 120 ° C. to 220 ° C., more preferably 180 ° C. or less. As the condensing agent, for example, magnesium oxide, zinc chloride, aluminum chloride or the like can be used.

The compound which is the final product obtained by the above synthesis scheme is processed in accordance with a post-treatment method of a normal organic synthesis reaction and then purified, for example, for a desired use such as an ink coloring material (dye). Can be used. For identification of the compound represented by the general formula (1), ¹ H-NMR analysis, LC / MS analysis, UV / Vis spectroscopic analysis and the like can be used.

  Preferable examples of the compound represented by the general formula (1) include Exemplified Compounds 1 to 42 shown in Tables 1 and 2. In the present invention, the compound represented by the general formula (1) is not limited to the exemplified compounds shown below as long as it is included in the structure and definition of the compound represented by the general formula (1). As the compound represented by the general formula (1), Exemplified Compounds 1 to 6 are preferable among the exemplified compounds shown below. In Tables 1 and 2, “Me” is methyl, “Et” is ethyl, “n-Pr” is normal propyl, “i-Pr” is isopropyl, “t-Bu” is tertiary butyl, and “EtO” is ethoxy. "PhO" represents phenoxy. “*” Represents a binding site of the substituent.

[Color material of second ink: other color materials]
It is useful for the present inventors to use a compound having a structure different from that of the general formula (1) in addition to the compound represented by the general formula (1) as the coloring material of the second ink. I found out. Thereby, light resistance can further be improved, without impairing the outstanding color developability which the compound represented by General formula (1) has.

Examples of the compound (other colorant) having a structure different from that of the general formula (1) that can be used in addition to the compound represented by the general formula (1) include pigments and dyes. More preferably, it is used. As other color materials, materials of any hue classified into cyan, magenta, yellow, red, blue, green, black and the like may be used. In particular, it is preferable to use a dye having a hue of magenta to red, and it is more preferable to use a dye such as a compound having an azo skeleton or an anthrapyridone skeleton. More specifically, a compound having a maximum absorption wavelength (λ _max ) in water of 380 to 590 nm, particularly 480 to 570 nm, particularly 500 to 560 nm, from the viewpoint of obtaining a further improvement effect of color developability. It is preferable to use it.

  Examples of the compound having an azo skeleton include C.I. I. Acid Red 249 (Azo Compound 1), and those described in JP-A No. 08-073791, JP-A No. 2002-371214, JP-A No. 2006-143898, and the like. Specific examples include compounds represented by the following general formula (I) and compounds represented by the following general formula (II). Moreover, the following are mentioned as a compound which has an anthrapyridone skeleton. For example, monomer structures described in International Publication No. 1998/011167, International Publication No. 1998/011167, International Publication No. 2004/104108, International Publication No. 2009/060654, International Publication No. 2009/093433, and the like. And so on. Moreover, the thing of the dimer structure etc. which were described in international publication 2003027185, international publication 2006/0775706, international publication 2008/066062, Unexamined-Japanese-Patent No. 2010-006969, etc. are mentioned. Specific examples include compounds represented by the following general formula (III), compounds represented by the following general formula (IV), and the like. Of course, the present invention is not limited to the following compounds.

  In each of the following structures, the alkyl preferably has 1 to 6 carbon atoms and the aryl has 6 to 10 carbon atoms. In addition, a group having a carbon atom that may have a substituent is substituted with a substituent such as an alkyl group, an aryl group, a hydroxy group, a halogen atom, a cyano group, a carboxy group, a sulfonic acid group, an alkylsulfonyl group, and an anilino group. It may be.

(In the general formula (I), R _{1 to} R ₄ each independently represents a hydrogen atom, a halogen atom, a cyano group, a carboxy group, a hydroxy group, a sulfonic acid group, or an alkyl group.)

(In general formula (II), R _{1 to} R ₈ each independently represents a hydrogen atom, a halogen atom, a cyano group, a carboxy group, a hydroxy group, a sulfonic acid group, or an alkyl group.)

(In general formula (III), R ₁ represents an alkylcarbonyl group, an alkoxycarbonyl group, an arylcarbonyl group, or an aryloxycarbonyl group. R ₂ represents a hydrogen atom or an alkyl group. R ₃ represents an anilino. Represents a group.)

(In general formula (IV), R ₁ represents an alkylcarbonyl group, an alkoxycarbonyl group, an arylcarbonyl group, or an aryloxycarbonyl group. R ₂ represents a hydrogen atom or an alkyl group. R ₃ represents an anilino. R ₄ represents a linking group.
Specific examples of the compound having an azo skeleton include azo compounds 1 to 4 having the following structure in the form of a free acid. Specific examples of the compound having an anthrapyridone skeleton include anthrapyridone compounds 1 to 9 having the following structure in the form of a free acid. Of course, the present invention is not limited to the following compounds.

  When a compound having a structure different from the general formula (1) is used as the color material of the second ink, the content (% by mass) of the compound in the ink is 0.10 mass based on the total mass of the ink. % Or more and 10.00% by mass or less is preferable. Furthermore, it is more preferable that it is 0.30 mass% or more and 5.00 mass% or less. Furthermore, in the case where a compound having a structure different from the general formula (1) is used as the coloring material of the second ink in addition to the compound represented by the general formula (1), the content of each compound is set as follows. It is preferable to do as follows. That is, in order to obtain a higher level of magenta color developability, the content (% by mass) of the compound represented by the general formula (1) in the ink is 0.35% by mass or more based on the total mass of the ink. Preferably there is. In this case, the upper limit of the content (% by mass) of the compound represented by the general formula (1) in the ink is 10.00% by mass or less, and further 5.00, as in the case described above. It is preferable that it is below mass%. The total content (% by mass) of each compound (coloring material) in the second 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 inventors of the present invention include a compound represented by the general formula (1) and a compound having a structure different from the general formula (1) in the second ink at a specific mass ratio, thereby providing a high level of color developability. In addition, the inventors have found that light resistance can be further improved while maintaining moisture resistance and ozone resistance. Specifically, the content (mass%) of the compound represented by the general formula (1) based on the total mass of the ink has a structure (mass%) having a structure different from that of the general formula (1). %), The mass ratio is preferably 0.10 times or more and 9.00 times or less. The mass ratio is more preferably 0.10 times or more and 1.00 times or less.

(Aqueous medium)
Each ink constituting the ink set of the present invention may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. Each ink is preferably 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 10.00% by mass or more and 90.00% 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 preferably from 5.00% by mass to 90.00% by mass based on the total mass of the ink, and from 10.00% by mass to 50.00%. More preferably, it is at most mass%. If the content of the water-soluble organic solvent is out of the above range, the ink ejection stability may be insufficient.

(Other additives)
In addition to the above-described components, each ink constituting the ink set of the present invention includes, if necessary, polyhydric alcohols such as trimethylolpropane and trimethylolethane; water-soluble organic solids at room temperature such as urea and derivatives thereof A compound may be contained. Furthermore, each ink constituting the ink set of the present invention includes a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, and an evaporation accelerator as necessary. Various additives such as a chelating agent and a water-soluble resin may be contained.

  The first ink and the second ink preferably contain a surfactant. The content (% by mass) of the surfactant in each ink is preferably 0.05% by mass or more and 2.00% by mass or less based on the total mass of the ink. The first ink preferably contains a surfactant such as acetylene glycol, fluorine, silicone, or polyoxyethylene alkyl ether. The second ink preferably contains an acetylene glycol surfactant. Among these, since the second ink is excellent in solubility in an aqueous medium, it is particularly preferable to contain an ethylene oxide adduct of acetylene glycol.

The first ink preferably contains a salt formed by combining a cation and an anion. By containing salt in the first ink, the optical density of an image recorded with the first ink can be improved. Furthermore, bleeding resistance at the boundary between the image recorded with the first ink and the image recorded with the second ink can be improved. Examples of the cation constituting the salt include alkali metal ions such as lithium ions, sodium ions, and potassium ions; ammonium ions; organic ammonium ions. Of these, potassium ion and ammonium ion are preferable. The anions constituting the salt include Cl ⁻ , Br ⁻ , I ⁻ , ClO ⁻ , ClO ₂ ⁻ , ClO ₃ ⁻ , ClO ₄ ⁻ , NO ₂ ⁻ , NO ₃ ⁻ , SO ₄ ²⁻ , CO ₃ ^{2. −} , HCO ₃ ⁻ , HCOO ⁻ , (COO ⁻ ) ₂ , COOH (COO ⁻ ), CH ₃ COO ⁻ , C ₂ H ₄ (COO ⁻ ) ₂ , C ₆ H ₅ COO ⁻ , C ₆ H ₄ (COO ⁻ ) ₂ , PO ₄ ³⁻ , HPO ₄ ²⁻ , H ₂ PO ₄ ^{− and the} like. The form of the salt in the ink may be in any of a dissociated state and a dissociated state.

  The first ink only needs to contain a salt in a range where the above-described effects can be obtained. Specifically, the salt content (% by mass) in the first ink is preferably 0.05% by mass or more and 10.00% by mass or less based on the total mass of the ink. If the salt content in the first ink exceeds 10.00% by mass, the storage stability of the ink may be insufficient. On the other hand, if the salt content in the first ink is less than 0.05% by mass, the above effects may be insufficient.

(Ink physical properties)
The static surface tension at 25 ° C. of each ink constituting the ink set of the present invention is preferably 10 mN / m or more and 60 mN / m or less. Further, it is more preferably 20 mN / m or more and 60 mN / m or less, and particularly preferably 30 mN / m or more and 40 mN / m or less. Each ink constituting the ink set of the present invention has a surface tension within the above-described range, so that when it is applied to an ink jet system, the ejection deviation due to wetting in the vicinity of the ejection opening (displacement of ink landing point), etc. Generation | occurrence | production can be suppressed effectively. The surface tension of the ink can be adjusted by appropriately setting the content of a surfactant or the like in the ink.

  The dynamic surface tension of the first ink at 25 ° C. and a lifetime of 50 milliseconds is preferably 40 mN / m or more, and more preferably 45 mN / m or more. By using the first ink having a dynamic surface tension in the above range, the pigment can be present particularly efficiently on the surface of the recording medium, and an image having a higher optical density can be recorded. The dynamic surface tension of the ink is measured by the maximum bubble pressure method. In the maximum bubble pressure method, the surface tension is obtained by measuring the maximum pressure required to release bubbles pushed out from the tip of a probe (thin tube) immersed in the liquid to be measured. “Lifetime” is the maximum bubble pressure method. When bubbles are formed from the tip of the probe, when a new surface is formed after the bubbles are released, the maximum bubble pressure (the radius of curvature of the bubble and the probe tip) Time until the radius of the part becomes equal).

  Each ink constituting the ink set of the present invention is preferably adjusted to a desired pH and viscosity so that good ejection characteristics can be obtained when applied to an ink jet recording apparatus. The pH at 25 ° C. of each ink constituting the ink set of the present invention is preferably 5.0 or more and 10.0 or less. The viscosity at 25 ° C. of each ink constituting the ink set of the present invention is preferably 1.0 mPa · s or more and 5.0 mPa · s or less.

<Inkjet recording method>
The ink jet recording method of the present invention is a method of recording an image on a recording medium by ejecting each ink constituting the ink set 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 preferable to employ a method in which thermal energy is applied to the ink and the ink is ejected. Except for using each ink constituting the ink set of the present invention, the steps of the ink jet recording method and the constitution of the ink jet recording apparatus may be known ones. In order to more effectively suppress the back-through of the secondary color image, it is preferable to apply the second ink after applying the first ink to the recording medium.

  6A and 6B are diagrams schematically illustrating an example of an ink jet recording apparatus used in the ink jet recording method of the present invention, in which FIG. 6A is a perspective view of a main part of the ink jet recording apparatus, and FIG. 6B 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. What is described as “parts” and “%” with respect to the component amounts is based on mass unless otherwise specified.

<Preparation of pigment dispersion>
(Pigment dispersion 1)
A solution prepared by dissolving 5 g of concentrated sulfuric acid in 5.5 g of water was cooled to 5 ° C., and 0.84 g (4.64 mmol) of 4-amino-1,2-benzenedicarboxylic acid was added. Potassium nitrite obtained by dissolving 2.2 g (26 mmol) of potassium nitrite in 9 g of water at 5 ° C. while the solution temperature is kept at 10 ° C. or lower while the container containing the solution is put in an ice bath. The solution was added. After further stirring for 15 minutes, 6 g of carbon black (trade name “Black Pearls 1100”, manufactured by Cabot) was added with stirring. Furthermore, the slurry obtained by stirring for 15 minutes was filtered with a filter paper (trade name “standard filter paper No. 2”, manufactured by Advantech) to obtain particles. The obtained particles were sufficiently cooled with water and then dried in an oven at 110 ° C. Next, water was added to obtain a dispersion liquid in which a self-dispersing pigment having —C ₆ H ₃ — (COOH) ₂ groups bonded to the particle surface was dispersed, the pigment content being 10.0%. By replacing potassium ions with ammonium ions by an ion exchange method, a self-dispersing pigment having a pigment content of 10.0% and having —C ₆ H ₃ — (COONH ₄ ) ₂ groups bonded to the particle surface was dispersed. A pigment dispersion 1 was obtained.

(Pigment dispersion 2)
Using a Silverson mixer, 20 g of carbon black (solid content), 9 mmol of ((4-aminobenzoylamino) -methane-1,1-diyl) bisphosphonic acid monosodium salt, 20 mmol of nitric acid, and 200 mL of pure water were mixed. did. As carbon black, a trade name “Black Pearls 880” (manufactured by Cabot) was used. Mixing was performed at 6,000 rpm under room temperature conditions. After 30 minutes, 20 mmol of sodium nitrite dissolved in a small amount of water was slowly added to the resulting mixture. The temperature of the mixture reached 60 ° C. by the addition of sodium nitrite. It was made to react in this state for 1 hour. Thereafter, an aqueous sodium hydroxide solution was added to adjust the pH of the mixture to 10. After 30 minutes, 20 mL of pure water was added, and diafiltration was performed using a spectrum membrane. Thereby, the self-dispersion in which the content of the pigment is 10.0% and the —C ₆ H ₄ —CONH—CH— (PO (OH) (ONa)) (PO (OH) ₂ ) group is bonded to the particle surface. A dispersion in which the pigment was dispersed was obtained. By substituting sodium ions to ammonium ions by an ion exchange method, the content of the pigment is _{10.0%, -C 6 H 4 -CONH} -CH- (PO (OH) (ONH 4)) on the particle surface ( A pigment dispersion 2 was obtained in which a self-dispersing pigment having a PO (OH) ₂ ) group bonded thereto was dispersed.

<Synthesis of Compound Represented by General Formula (1)>
The compound represented by the general formula (1) synthesized below was identified by the following analysis methods.
[1] ¹ H NMR analysis: ¹ H nuclear magnetic resonance spectroscopy (ECA-400; manufactured by JEOL Ltd.).
[2] LC / MS analysis: LC / TOF MS (LC / MSD TOF; manufactured by Agilent Technologies). As an ionization method, an electrospray ionization method (ESI) was used.
[3] UV / Vis spectroscopic analysis: UV / Vis spectrophotometer (UV-3600 type spectrophotometer; manufactured by Shimadzu Corporation).

(Exemplary Compound 1)
N- (3-amino-2,4,6-trimethylphenyl) -2,2-dimethylbutanamide (7.5 g) and compound (A) (7.4 g) in the above synthesis scheme were combined with sulfolane (20 mL). In the presence of zinc chloride (4.1 g), the reaction was carried out by heating at 150 ° C. for 3 hours. After cooling this solution, it was added to 50 mL of 2 mol / L hydrochloric acid, and the precipitated crystals were collected by filtration, washed with water, and then dried to obtain a dried product. 6 g of the obtained dried product was added to 30 g of fuming sulfuric acid under ice cooling, and then stirred at a temperature of 30 to 32 ° C. for 24 hours. The reaction solution was discharged onto 100 g of ice, and the precipitated sulfonated product was collected by filtration and then washed with cold water to obtain a precipitate. The obtained precipitate was suspended in 50 mL of water, dissolved in 2 mol / L sodium hydroxide aqueous solution to pH 7.0, crystallized with acetone, and exemplified compound 1 represented by the following structural formula Got.

It was confirmed by [1] ¹ H NMR analysis, [2] LC / TOF MS analysis, and [3] UV / Vis spectroscopic analysis that Exemplified Compound 1 obtained had the above structure. The analysis results are shown below.
[1] Results of ¹ H NMR (400 MHz, DMSO-d ₆ , temperature 80 ° C.) (see FIG. 1):
δ [ppm] = 9.63 (s, 2H), 8.69 (s, 2H), 8.05 (d, 1H), 7.67 (t, 1H), 7.62 (s, 2H), 7.57 (t, 1H), 7.26 (d, 1H), 7.11 (t, 2H), 5.97 (s, 2H), 2.30-1.80 (m, 18H), 1 .65-1.60 (m, 4H), 1.21 (s, 12H), 0.88 (s, 6H)
[2] Results of LC / TOF MS analysis (eluent: 0.1% aqueous acetic acid-methanol, ESI):
Retention time 12.5 minutes: Purity = 99.9 area%, m / z = 987.30 [n = 2, (M-2Na + H) ⁻ ]
[3] Results of UV / Vis spectroscopic analysis (see FIG. 5):
λ _max = 533 nm, ε = 87198 M ⁻¹ cm ⁻¹ (in water, temperature 25 ° C.).

(Exemplary Compound 5)
N- (3-amino-2,4,6-trimethylphenyl) -3,3-dimethylbutanamide (19.0 g) and compound (A) (7.4 g) in the above synthesis scheme were combined with N-methyl. -The reaction was performed in pyrrolidone (50 mL) by heating at 150 ° C for 6 hours. After cooling this solution, it was added to 100 mL of 2 mol / L hydrochloric acid, and the precipitated crystals were collected by filtration, washed with water, and dried to obtain a dried product. 6 g of the obtained dried product was added to 30 g of fuming sulfuric acid under ice cooling, and then stirred at a temperature of 30 to 32 ° C. for 24 hours. The reaction solution was discharged onto 100 g of ice, and the precipitated sulfonated product was collected by filtration and then washed with cold water to obtain a precipitate. The obtained precipitate was suspended in 50 mL of water, dissolved in 2 mol / L sodium hydroxide aqueous solution to pH 7.0, crystallized with acetone, and exemplified compound 5 represented by the following structural formula Got.

It was confirmed by [1] ¹ H NMR analysis, [2] LC / TOF MS analysis, and [3] UV / Vis spectroscopic analysis that Exemplified Compound 5 obtained had the above structure. The analysis results are shown below.
[1] Results of ¹ H NMR (400 MHz, DMSO-d ₆ , temperature 80 ° C.) (see FIG. 2):
δ [ppm] = 9.65-9.55 (m, 2H), 9.01 (s, 1H), 8.99 (s, 1H), 8.05 (d, 1H), 7.68 (t 1H), 7.61 (s, 2H), 7.58 (t, 1H), 7.25 (d, 1H), 7.11 (s, 1H), 7.10 (s, 1H), 6 .01 (s, 2H), 2.30-1.95 (m, 22H), 1.08-1.04 (m, 18H)
[2] Results of LC / TOF MS analysis (eluent: 0.1% aqueous acetic acid-methanol, ESI):
Retention time 12.3 minutes: Purity = 99.9 area%, m / z = 987.30 [n = 2, (M-2Na + H) ⁻ ]
[3] Results of UV / Vis spectroscopic analysis (see FIG. 5):
λ _max = 534 nm, ε = 88061 M ⁻¹ cm ⁻¹ (in water, temperature 25 ° C.).

(Exemplary Compound 6)
N- (3-amino-2,4,6-trimethylphenyl) hexanamide (20 g) and compound (A) (7.4 g) in the above synthesis scheme were combined with zinc chloride (4. 4) in sulfolane (20 mL). In the presence of 1 g), the reaction was carried out by heating at a temperature of 150 ° C. for 3 hours. After cooling this solution, it was added to 50 mL of 2 mol / L hydrochloric acid, and the precipitated crystals were collected by filtration, washed with water, and dried to obtain a dried product. 6 g of the obtained dried product was added to 30 g of fuming sulfuric acid under ice cooling, and then stirred at a temperature of 30 to 32 ° C. for 24 hours. The reaction solution was discharged onto 100 g of ice, and the precipitated sulfonated product was collected by filtration and then washed with cold water to obtain a precipitate. The obtained precipitate was suspended in 50 mL of water, dissolved in 2 mol / L sodium hydroxide aqueous solution to pH 7.0, crystallized with acetone, and exemplified compound 6 represented by the following structural formula Got.

It was confirmed by [1] ¹ H NMR analysis, [2] LC / TOF MS analysis, and [3] UV / Vis spectroscopic analysis that Exemplified Compound 6 obtained had the above structure. The analysis results are shown below.
[1] Results of ¹ H NMR (400 MHz, DMSO-d ₆ , temperature 80 ° C.) (see FIG. 3):
δ [ppm] = 9.62-9.58 (m, 2H), 9.07-9.02 (m, 2H), 8.04 (d, 1H), 7.66 (t, 1H), 7 .60 (s, 2H), 7.57 (t, 1H), 7.25 (d, 1H), 7.15-7.09 (m, 2H), 5.98 (s, 2H), 2. 32-1.94 (m, 22H), 1.63 (s, 4H), 1.34 (s, 8H), 0.88 (s, 6H)
[2] Results of LC / TOF MS analysis (eluent: 0.1% aqueous acetic acid-methanol, ESI):
Retention time 12.5 minutes: Purity = 99.8 area%, m / z = 987.30 [n = 2, (M-2Na + H) ⁻ ]
[3] Results of UV / Vis spectroscopic analysis (see FIG. 5):
λ _max = 533 nm, ε = 85649 M ⁻¹ cm ⁻¹ (in water, temperature 25 ° C.).

(Exemplary Compound 15)
N- (3-amino-2,4,6-trimethylphenyl) octanamide (19.0 g) and compound (A) (7.0 g) in the above synthesis scheme were combined with zinc chloride (50 mL) in zinc chloride ( In the presence of 10.0 g), the reaction was carried out by heating at a temperature of 150 ° C. for 3 hours. After cooling this solution, it was added to 100 mL of 2 mol / L hydrochloric acid, and the precipitated crystals were collected by filtration, washed with water, and dried to obtain a dried product. 6 g of the obtained dried product was added to 30 g of fuming sulfuric acid under ice cooling, and then stirred at a temperature of 20 to 25 ° C. for 4 hours. The reaction solution was discharged onto 100 g of ice, and the precipitated sulfonated product was collected by filtration and then washed with cold water to obtain a precipitate. The obtained precipitate was suspended in 50 mL of water, dissolved in a 2 mol / L sodium hydroxide aqueous solution at pH 7.0, crystallized with acetone, and exemplified compound 15 represented by the following structural formula. Got.

It was confirmed by [1] ¹ H NMR analysis and [2] LC / TOF MS analysis that the exemplified compound 15 obtained had the above structure. The analysis results are shown below.
[1] Results of ¹ H NMR (400 MHz, DMSO-d ₆ , temperature 80 ° C.) (see FIG. 4):
δ [ppm] = 9.64 (s, 2H), 9.06 (t, 2H), 8.05 (d, 1H), 7.67 (t, 1H), 7.62 (s, 2H), 7.57 (t, 1H), 7.26 (d, 1H), 7.11 (t, 2H), 5.99 (s, 2H), 2.40-1.80 (m, 20H), 1 .64 (s, 4H), 1.00-1.80 (m, 18H), 0.87 (s, 6H)
[2] Results of LC / TOF MS analysis (eluent: 0.1% aqueous acetic acid-methanol, ESI):
Retention time 16.4 minutes: Purity = 99.9 area%, m / z = 1043.36 [n = 2, (M-2Na + H) ⁻ ]
[3] Results of UV / Vis spectroscopic analysis (see FIG. 5):
λ _max = 533 nm, ε = 85950 M ⁻¹ cm ⁻¹ (in water, temperature 25 ° C.).

<Preparation of ink>
Each component (unit:%) shown in Table 3 was mixed and stirred sufficiently, and then pressure filtered through a polypropylene filter (made by Pole) having a pore size of 2.5 μm to prepare a first ink. Moreover, after mixing each component (unit:%) shown in Table 4 and fully stirring, it pressure-filtered with the micro filter (product made from Fuji Film) with the pore size of 0.2 micrometer, and prepared the 2nd ink. “Acetylenol E100” in Tables 3 and 4 is a trade name of a nonionic surfactant (manufactured by Kawaken Fine Chemicals). Comparative compounds 1 and 2 are compounds having the following structures. Anthrapyridone compound 3 was used as a sodium salt.

<Evaluation>
Each ink obtained above was filled in an ink cartridge to obtain an ink set having a combination shown in Table 6. Then, the following items were evaluated. The color of the image was measured using a spectrophotometer (trade name “Spectorolino”, manufactured by Gretag Macbeth) under the conditions of light source: D50 and field of view: 2 °. L ^{*, a *} and ^{b *, L} * in ^{the L} * ^a * ^{b *} display system defined by the CIE (Commission Internationale de l'Eclairage), is ^{a *} and ^{b *.} The evaluation results are shown in Table 6. In the present invention, “AA”, “A”, and “B” are acceptable levels, and “C” and “D” are unacceptable levels in the evaluation criteria for the following evaluation items.

(Dark color reproduction range)
The ink cartridge filled with each ink was mounted on an ink jet recording apparatus (trade name “PIXUS MP490”, manufactured by Canon) that ejects ink from the recording head by the action of thermal energy. The first ink was set at the black ink position, and the second ink was set at the magenta ink position. A pattern (secondary color image) containing a secondary color solid image was printed on plain paper (trade name “Canon” under the conditions of a temperature of 23 ° C. and a relative humidity of 55% under the recording conditions of Nos. 1 to 9 shown in Table 5. Recorded in “Office Paper” (Canon).

L ^* , a ^*, and b ^* of the solid images in the nine secondary color images recorded under the recording conditions of Nos. 1 to 9 were measured. C ^* = {(a ^* ) ² + (b ^* ) ² } Saturation C ^* is calculated based on the equation of ^1/2 , and the horizontal axis represents saturation C ^* and the vertical axis represents lightness L ^*. C ^* and L ^* of the image were plotted. Then, the color reproduction range of the dark part was evaluated from the viewpoint of “whether at least one of the solid images satisfies the following condition”.
^A: L * = is the 40 ^{C *} is 30 or more in, ^and, L * = ^C in 35 ^* was 20 or more ^B: is the L * = 40 ^{C *} is 30 or more in, ^{and, L} * = C ^{* at} 35 was less than 20: C ^{* at} L ^* = 40 was less than 30, and C ^{* at} L ^* = 35 was less than 20.

(Suppression of strikethrough)
The ink cartridge filled with each ink was mounted on an ink jet recording apparatus (trade name “PIXUS MP490”, manufactured by Canon) that ejects ink from the recording head by the action of thermal energy. The first ink was set at the black ink position, and the second ink was set at the magenta ink position. Then, a pattern (secondary color image) including a secondary color solid image was printed on plain paper (product name “PB” under the recording conditions of numbers 10 to 13 shown in Table 5 under the conditions of a temperature of 23 ° C. and a relative humidity of 55%. PAPER ", manufactured by Canon Inc.). At this time, an image was recorded under the following two conditions. The image of “Condition 1” is a condition in which half of the recording target region is applied in the order of the first ink and the second ink, and the other half is applied in the order of the second ink and the first ink so that the respective inks overlap each other. FIG. 6 is a solid image in which areas (unit areas) having different application orders are arranged and recorded in a staggered manner. In addition, the image of “condition 2” is an image recorded under the condition that the respective inks are applied so as to overlap each other in the order of the first ink and the second ink in all the areas to be recorded. The state of whether or not the magenta color of the second ink oozes out on the back surface of the image recorded under each condition was visually observed, and the suppression of showthrough was evaluated according to the following criteria.
A: There was no show-through in any of the images of conditions 1 and 2. B: There was no show-through in the image of condition 1, but there was a show-through in the image of condition 2. C: Conditions 1 and 2 There was a show-through in any of the images

(Color development of images recorded with the second ink)
The ink cartridge filled with the second ink was 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 8 ink droplets of 2.5 pL per droplet to a unit area of 1/600 inch × 1/600 inch is recorded as “recording duty is 100%”. Define. Using this ink jet recording apparatus, 10 types of solid images in which the recording duty is changed from 10% to 100% in 10% increments are recorded on glossy paper in an environment of a temperature of 23 ° C. and a relative humidity of 55%. Got. As the glossy paper, a trade name “Canon Photo Paper / Glossy Pro [Platinum Grade] PT-201” (manufactured by Canon) was used. The obtained recorded matter was dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 55%.

A ^* and b ^* of a solid image of each recording duty in the obtained recorded matter were measured. Then, saturation C ^* = {(a ^* ) ² + (b ^* ) ² } ^1/2 was calculated from the values of a ^* and b ^* of a solid image with a recording duty of 100%. Further, a solid image having a value of a ^* closest to 75 among 10 types of solid images was identified, and the hue angle H ° was calculated from the values of a ^* and b ^* of the solid image based on the following formula.
When a ^* ≧ 0 and b ^* ≧ 0 (first quadrant), the hue angle H ° = tan ⁻¹ (b ^* / a ^* )
When a ^* ≦ 0 and b ^* ≧ 0 (second quadrant), the hue angle H ° = 180 + tan ⁻¹ (b ^* / a ^* )
When a ^* ≦ 0 and b ^* ≦ 0 (third quadrant), the hue angle H ° = 180 + tan ⁻¹ (b ^* / a ^* )
When a ^* ≧ 0 and b ^* ≦ 0 (fourth quadrant), the hue angle H ° = 360 + tan ⁻¹ (b ^* / a ^* )
From the obtained C ^* and H ° values, the color developability of the image recorded with the second ink was evaluated according to the following evaluation criteria.
A: H ° was 335 or more and less than 345, and C ^* was 83 or more B: H ° was 335 or more and less than 345, and C ^* was 80 or more and less than 83 C: H ° Was 0 or more and less than 335, or 345 or more and less than 360, or C ^* was less than 80.

(Light resistance of images recorded with the second ink)
A solid image having a recording duty of 100% was recorded under the same conditions as in the case of the evaluation of “color development of an image recorded with the second ink” to obtain a recorded matter. The obtained recorded matter was dried at a temperature of 23 ° C. and a relative humidity of 55% for 24 hours, and then the optical density of the solid image was measured (referred to as “optical density before test”). Next, the recorded matter was put into a xenon test apparatus (trade name “Xenon Weather Meter SX-75”, manufactured by Suga Test Instruments Co., Ltd.), and 288 xenon light was applied to the solid image under the conditions of a bath temperature of 23 ° C., a relative humidity of 50%, and an illuminance of 50 klx. Irradiated for hours. After irradiation with xenon light, the optical density of the solid image of the recorded material was measured (referred to as “optical density after test”). Then, the residual ratio of optical density (%) = (optical density after test / optical density before test) × 100 was calculated, and the light resistance of the image recorded with the second ink was evaluated according to the evaluation criteria shown below. .
A: The residual ratio of optical density was 85% or more B: The residual ratio of optical density was 80% or more and less than 85% C: The residual ratio of optical density was less than 80%.

(Moisture resistance of images recorded with the second ink)
Except for changing the recording medium to glossy paper (trade name “Canon Photo Paper / Glossy Gold GL-101”, manufactured by Canon), the same as in the case of the evaluation of “color development of an image recorded with the second ink” above. Under the conditions, an image having the following pattern was recorded to obtain a recorded matter. In this pattern, a solid image having a recording duty of 100% and a non-recording portion of the same size are arranged in a grid pattern. The obtained recorded matter was dried in an environment of a temperature of 23 ° C. and a relative humidity of 55% for 24 hours, and then L ^* , a ^* and b ^* of the solid image were measured (L ₁ ^* , a ₁ ^* and b ₁ ^* ). This recorded matter was placed in a constant temperature and humidity chamber at a temperature of 30 ° C. and a relative humidity of 90% for 168 hours. Thereafter, L ^* , a ^* and b ^* of the solid image were measured (referred to as L ₂ ^* , a ₂ ^* and b ₂ ^* ). Then, the color change (ΔE) = {(L ₁ ^* −L ₂ ^* ) ² + (a ₁ ^* −a ₂ ^* ) ² + (b ₁ ^* −b ₂ ^* ) ² } ^1/2 is calculated, The moisture resistance of the image recorded with the second ink was evaluated according to the evaluation criteria shown in FIG.
A: ΔE was less than 5 A: ΔE was 5 or more and less than 8 B: ΔE was 8 or more and less than 10 C: ΔE was 10 or more and less than 15 D: ΔE was 15 or more It was.

Claims (9)

An ink set having a combination of a first ink and a second ink,
The first ink contains a self-dispersing pigment in which an ionic group is chemically bonded to the pigment particle surface directly or through another atomic group,
The ink set, wherein the second ink contains a compound represented by the following general formula (1).

(In the general formula (1), R ₁ , R ₅ , R ₆ and R ₁₀ each independently represents an alkyl group. R ₃ and R ₈ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, aryloxy. R ₂ , R ₄ , R ₇ and R ₉ each independently represents a hydrogen atom, an ionic group, or a group represented by the following general formula (2), R ₂ , At least one of R ₄ , R ₇ and R ₉ represents a group represented by the following general formula (2): Z independently represents a sulfonic acid group or a sulfamoyl group, and R ₂ , R ₃ , R ₄ , at least one of R ₇ , R ₈ and R ₉ has an ionic group, n represents an integer of 0 to 6, and R ₂ , R ₃ , R ₄ , R ₇ , R ₈ and R ₉ are When there is no ionic group, n represents an integer of 1 to 6, and Z is present In some cases, the aromatic ring in the general formula (1) is substituted at the position of at least one hydrogen atom.)

(In General Formula (2), R ₁₁ represents an alkyl group having 5 to 7 carbon atoms.) R ₃ and R ₈ in the general formula (1) are each independently an alkyl group having 1 to 3 carbon atoms, and R ₁₁ in the general formula (2) is a group having 5 to 7 carbon atoms. The compound according to claim 1, which is an alkyl group.   The compound according to claim 1 or 2, wherein the number of groups represented by the general formula (2) in the general formula (1) is 2 or more and 4 or less.   The compound according to any one of claims 1 to 3, wherein n in the general formula (1) is an integer of 1 to 6 and Z is a sulfonic acid group. The compound according to any one of claims 1 to 4, wherein R ₁ , R ₅ , R ₆ and R _{10 in the} general formula (1) are each independently an alkyl group having 1 to 3 carbon atoms. The compound according to any one of claims 1 to 5, wherein R ₃ and R ₈ in the general formula (1) are each independently an alkyl group having 1 to 3 carbon atoms. The R ₁ and R ₆ , R ₂ and R ₇ , R ₃ and R ₈ , R ₄ and R ₉ , R ₅ and R _{10 in the} general formula (1) are respectively the same group. The compound according to any one of the above. An ink jet recording method for recording an image on a recording medium by discharging ink from an ink jet recording head,
An ink jet recording method, wherein the ink is a first ink and a second ink constituting the ink set according to any one of claims 1 to 7. The ink jet recording method according to claim 8, wherein the second ink is applied after the first ink is applied to the recording medium.