JP2017171730A - Ink, ink cartridge and ink jet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ink that is superior in color development and humidity resistance.SOLUTION: Ink for ink jet contains a first coloring material consisting of an anthrapyridone-based coloring material having a specified structure, and a second coloring material consisting of a xanthene-based coloring material having a specified structure.SELECTED DRAWING: None

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, there is a problem that the color material of the image deteriorates when exposed to environmental gas such as light, humidity, heat, ozone gas existing in the air for a long time, and color change or fading easily occurs.

  Moisture resistance refers to resistance to a phenomenon such as a change in color tone or bleeding caused by moisture in the atmosphere. As a color material of magenta ink, an anthrapyridone color material, an azo color material, a xanthene color material, and the like are widely used. Many xanthene-based color materials that can record images with good color development have small molecular skeletons, and the moisture resistance of images tends to be low. Further, when an image is recorded using an anthrapyridone color material or an azo color material having a large molecular skeleton, the moisture resistance is improved but the color developability tends to be lowered.

  In recent years, an anthrapyridone color material capable of recording an image excellent in moisture resistance and the like has been proposed (Patent Documents 1 and 2). In addition, xanthene-based color materials capable of recording images with excellent color developability have been proposed (Patent Documents 3 and 4). Further, there has been proposed a magenta ink capable of recording an image having good color tone and light fastness by containing an anthrapyridone color material and an azo color material (Patent Documents 5 and 6). Further, there has been proposed a magenta ink capable of recording an image having good color tone and light fastness by containing a xanthene color material and an azo color material (Patent Documents 7 and 8).

Japanese Patent No. 5145243 Japanese Patent No. 522995 JP 2011-148773 A JP 2012-193111 A JP-A-2005-105136 JP 2005-307068 A JP 2007-217524 A JP 2007-217525 A

  However, as a result of the study by the present inventors, when an ink containing only the dye proposed in Patent Documents 1 and 2 is used, it is difficult to record an image having a high level of color development required in recent years. I found out. In addition, even when using inks or ink sets containing only the dyes proposed in Patent Documents 3 and 4, it is difficult to achieve both the color developability and moisture resistance of images at a high level required in recent years. It was. In particular, it has been found that the dyes proposed in Patent Documents 3 and 4 are insufficient to suppress changes in color tone of an image due to moisture in the atmosphere. Furthermore, it has been found that, in the combination of dyes used in the inks proposed in Patent Documents 5 to 8, the coexistence of color developability and moisture resistance is insufficient. That is, it has been found that it is difficult for the conventional technology to achieve both the color development and the moisture resistance of images at a high level required in recent years.

  Accordingly, an object of the present invention is to provide an ink capable of recording an image having excellent color developability and moisture 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 first color material and a second color material, wherein the first color material is a compound represented by the following general formula (1): There is provided an ink characterized in that the second colorant is a compound represented by the following general formula (2).

（前記一般式（１）中、Ｒ₁はそれぞれ独立に、水素原子、アルキル基、ヒドロキシアルキル基、シクロアルキル基、モノアルキルアミノアルキル基、又はジアルキルアミノアルキル基を表し、Ｒ₂はそれぞれ独立に、下記式（ｉ）乃至（ｉｖ）のいずれかで表される基を表し、Ｘは連結基を表し、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 (1), each R ₁ independently represents a hydrogen atom, an alkyl group, a hydroxyalkyl group, a cycloalkyl group, a monoalkylaminoalkyl group, or a dialkylaminoalkyl group, and each R ₂ independently represents Represents a group represented by any of the following formulas (i) to (iv), X represents a linking group, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium.

（前記式（ｉ）及び（ｉｉ）中、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。前記式（ｉｖ）中、Ｒ₃は水素原子、アルキル基、又はアルコキシ基を表す）

(In the formulas (i) and (ii), M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium. In the formula (iv), R ₃ represents a hydrogen atom, an alkyl group, or an alkoxy group. Represents a group)

（前記一般式（２）中、Ｒ₁はそれぞれ独立に、アルキル基、又はシクロアルキル基を表し、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 (2), each R ₁ independently represents an alkyl group or a cycloalkyl group, and each M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium)

  ADVANTAGE OF THE INVENTION According to this invention, the ink which can record the image excellent in coloring property and moisture resistance can be provided. 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”. Further, the physical property values are values at normal temperature (25 ° C.) unless otherwise specified.

  The inventors of the present invention have studied color materials capable of recording an image having both color developability and moisture resistance. Examples of the color material exhibiting a magenta color include an azo color material, a xanthene color material, and an anthrapyridone color material. However, even if an ink containing only one of these color materials is used, an image compatible with a high level of color developability and moisture resistance cannot be recorded. Further, even when an azo color material and an anthrapyridone color material are used together, or an azo color material and a xanthene color material are used together, it has not been possible to achieve both color development and moisture resistance.

  Therefore, the present inventors have studied an ink containing an anthrapyridone color material and a xanthene color material. As a result, it was found that when a specific anthrapyridone color material and a specific xanthene color material were used in combination, an image with improved color development and moisture resistance could be recorded. Specifically, it was found that by using the compound represented by the general formula (1) and the compound represented by the general formula (2) in combination, it is possible to record an image compatible with a high level of color developability and moisture resistance. . In particular, when an ink using a compound represented by the general formula (1) and a compound represented by the general formula (2) is used, an image is obtained as compared with the case where an ink containing each of these compounds alone is used. It has been found that the moisture resistance of is significantly improved.

  The present inventor has the reason why it is possible to record an image compatible with color development and moisture resistance at a high level by using the compound represented by the general formula (1) and the compound represented by the general formula (2) in combination. Have speculated as follows. Image degradation under high-humidity conditions is a phenomenon in which color change or blurring occurs in an image due to humidity. In general, the color tone of an anthrapyridone-based colorant and xanthene-based colorant changes in a greenish direction due to a change in humidity. On the other hand, the color of the compound represented by the general formula (1) changes in a greenish direction due to a change in humidity. That is, it is considered that the color change is mitigated by using a color material having a different directionality of the color that changes according to the humidity as compared with the case where each color material is used alone. A compound represented by the general formula (1) in which the color tone changes in the direction of green due to a change in humidity, and a general formula (2) in which the color tone changes in the direction of a blueness due to a change in humidity. It is considered that an image having excellent color developability and moisture resistance can be recorded by using in combination with the above compound.

<Ink>
The ink of the present invention is an inkjet ink containing a first color material and a second color material. And a 1st color material is a compound represented by General formula (1), and a 2nd color material is a compound represented by General formula (2). The components contained in the ink of the present invention and the physical properties of the ink will be described in detail.

(First color material)
The ink of the present invention contains a compound represented by the following general formula (1) as a first color material. This first color material is a water-soluble dye exhibiting a magenta color, and can be suitably used as a color material for ink having a magenta color tone.

（前記一般式（１）中、Ｒ₁はそれぞれ独立に、水素原子、アルキル基、ヒドロキシアルキル基、シクロアルキル基、モノアルキルアミノアルキル基、又はジアルキルアミノアルキル基を表し、Ｒ₂はそれぞれ独立に、下記式（ｉ）乃至（ｉｖ）のいずれかで表される基を表し、Ｘは連結基を表し、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 (1), each R ₁ independently represents a hydrogen atom, an alkyl group, a hydroxyalkyl group, a cycloalkyl group, a monoalkylaminoalkyl group, or a dialkylaminoalkyl group, and each R ₂ independently represents Represents a group represented by any of the following formulas (i) to (iv), X represents a linking group, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium.

（前記式（ｉ）及び（ｉｉ）中、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。前記式（ｉｖ）中、Ｒ₃は水素原子、アルキル基、又はアルコキシ基を表す）

(In the formulas (i) and (ii), M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium. In the formula (iv), R ₃ represents a hydrogen atom, an alkyl group, or an alkoxy group. Represents a group)

R ₁ in the general formula (1) independently represents a hydrogen atom, an alkyl group, a hydroxyalkyl group, a cycloalkyl group, a monoalkylaminoalkyl group, or a dialkylaminoalkyl group.

  Examples of the alkyl group include an alkyl group having 1 to 8 carbon atoms. More specifically, linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl; iso-propyl, sec-butyl And branched chain alkyl groups such as t-butyl and iso-butyl.

  Examples of the hydroxyalkyl group include a hydroxyalkyl group having 1 to 4 carbon atoms. More specifically, hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl and the like can be mentioned. Examples of the alkyl constituting the hydroxyalkyl group include straight chain, branched chain, and cyclic alkyl. Of these, linear alkyl is preferable. Moreover, although the substitution position of hydroxy in alkyl may be any position, it is preferable that hydroxy is substituted at the terminal of alkyl. Examples of such a hydroxyalkyl group include 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, and the like.

  Examples of the cycloalkyl group include cycloalkyl groups having 3 to 8 carbon atoms. More specific examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

  Examples of the monoalkylaminoalkyl group include a mono-carbon number 1 to 4 alkylamino-carbon number 1 to 4 alkyl group. More specific examples include monomethylaminopropyl and monoethylaminopropyl.

  Examples of the dialkylaminoalkyl group may include a di-carbon number 1 to 4 alkylamino-carbon number 1 to 4 alkyl group. More specifically, dimethylaminopropyl, diethylaminoethyl, etc. can be mentioned.

In the present invention, R ₁ in the general formula (1) is preferably a hydrogen atom, an alkyl group, or cyclohexyl, more preferably a hydrogen atom or an alkyl group, and particularly preferably a methyl group.

R ₂ in the general formula (1) independently represents a group represented by any one of the following formulas (i) to (iv). M in the formulas (i) and (ii) each independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium. R ₃ in formula (iv) represents a hydrogen atom, an alkyl group, or an alkoxy group.

  Specific examples of the group represented by formula (i) include 1-naphthyloxy and 2-naphthyloxy substituted with a carboxy group. Of these, 2-naphthyloxy is preferable. The substitution position of the carboxy group is preferably the 5-position, the 6-position, the 7-position, or the 8-position, and more preferably the 6-position, when the substitution position of the oxygen atom is the 1-position.

  In formulas (ii) to (iv), the substitution position of the atomic group whose substitution position is not specified is preferably the 2-position or the 4-position when the substitution position of the oxygen atom in the benzene ring is the first position. Is more preferable.

R ₃ in formula (iv) represents a hydrogen atom, an alkyl group, or an alkoxy group. R ₃ is preferably an alkyl group or an alkoxy group, and more preferably an alkoxy group. Examples of the alkyl group for R ₃ include linear, branched, and cyclic alkyl groups. Of these, linear alkyl is preferable. The alkyl group in R ₃ preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms. Specific examples of the alkyl group include a straight chain alkyl group such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl; iso-propyl, iso-butyl, Branched alkyl groups such as sec-butyl, t-butyl, iso-pentyl, iso-hexyl, iso-heptyl, iso-octyl; cyclo such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl An alkyl group can be mentioned.

Examples of the alkoxy group for R ₃ include linear and branched alkoxy groups. Of these, a linear alkoxy group is preferable. The alkoxy group in R ₃ preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms. Specific examples of the alkoxy group include linear alkoxy groups such as methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexyloxy, n-heptyloxy, n-octyloxy; iso-propoxy, iso-butoxy, Mention may be made of branched-chain alkoxy groups such as sec-butoxy, t-butoxy, iso-pentyloxy, iso-hexyloxy, iso-heptyloxy, iso-octyloxy and the like. Of these, n-propoxy is preferable.

R ₂ in the general formula (1) is preferably a group represented by the formula (i), the formula (ii), or the formula (iv), and the following formula (v), the following formula (vi), or The group represented by the following formula (vii) is more preferable.

  X in the general formula (1) is a linking group. Examples of this linking group include linking groups 1 to 7 shown below. In addition, the bond attached | subjected with "*" in the coupling groups 1 thru | or 7 shown below is a bond of each nitrogen atom. For this reason, each nitrogen atom in the linking groups 1 to 7 is directly bonded to two different triazine rings in the general formula (1). Among the connecting groups shown below, the following connecting group 1 or the following connecting group 2 is particularly preferable.

（連結基１中、ｎは２乃至８の数を表し、好ましくは２乃至６、さらに好ましくは２である。＊はそれぞれ異なる２つのトリアジン環との結合部位を表す）

(In the linking group 1, n represents a number of 2 to 8, preferably 2 to 6, and more preferably 2. * represents a bonding site with two different triazine rings.)

（連結基２中、Ｒ_aはそれぞれ独立に、水素原子又はメチル基を表す。＊はそれぞれ異なる２つのトリアジン環との結合部位を表す）

(In the linking group 2, each R _a independently represents a hydrogen atom or a methyl group. * Represents a bonding site with two different triazine rings.)

（連結基３中、＊はそれぞれ異なる２つのトリアジン環との結合部位を表す）

(In linking group 3, * represents a bonding site with two different triazine rings.)

（連結基４中、＊はそれぞれ異なる２つのトリアジン環との結合部位を表す）

(In the linking group 4, * represents a bonding site with two different triazine rings.)

（連結基５中、＊はそれぞれ異なる２つのトリアジン環との結合部位を表す）

(In the linking group 5, * represents a bonding site with two different triazine rings.)

（連結基６中、ｎは２乃至４の数を表す。＊はそれぞれ異なる２つのトリアジン環との結合部位を表す）

(In the linking group 6, n represents a number of 2 to 4. * represents a bonding site with two different triazine rings.)

（連結基７中、＊はそれぞれ異なる２つのトリアジン環との結合部位を表す）

(In the linking group 7, * represents a bonding site with two different triazine rings.)

  M in general formula (1), formula (i), formula (ii), formula (v), and formula (vi) is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium. Specific examples of the alkali metal include lithium, sodium, and potassium. Specific examples of organic ammonium include acetamide, benzamide, trimethylamino, butylamino, diethylamino, phenylamino, triethanolamino and the like. All of M are preferably sodium.

  Preferred specific examples of the compound represented by the general formula (1) include exemplified compounds 1 to 23 shown in Table 1. Of course, the compound represented by the general formula (1) is not limited to the following exemplary compounds as long as it is included in the structure of the general formula (1) and its definition.

In the present invention, since a higher level of color developability and moisture resistance can be obtained, in general formula (1), R ₁ is a hydrogen atom or a linear alkyl group having 1 to 4 carbon atoms, and X is linked. Group 1 or linking group 2 is preferred. Specifically, among the above exemplary compounds, exemplary compounds 1 to 4, 6, 7, 15, 16, 18, and 21 to 23 are preferable. Moreover, since higher levels of moisture resistance and ozone resistance are obtained, the first colorant is a compound represented by the following general formula (3) (M is independently a hydrogen atom, an alkali metal, ammonium, Or an organic ammonium). In addition, what showed the compound represented by General formula (3) as a free acid type is the illustration compound 1 in Table 1.

（前記一般式（３）中、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 (3), each M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium)

(Second color material)
The ink of the present invention contains a compound represented by the following general formula (2) as the second color material. This second color material is a water-soluble dye exhibiting a magenta color, and can be suitably used as a color material for ink having a magenta color tone.

（前記一般式（２）中、Ｒ₁はそれぞれ独立に、アルキル基、又はシクロアルキル基を表し、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 (2), each R ₁ independently represents an alkyl group or a cycloalkyl group, and each M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium)

In general formula (2), R < ₁ > represents an alkyl group or a cycloalkyl group each independently. Examples of the alkyl group include linear or branched alkyl groups having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. The alkyl group may have a substituent. 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 do. As the alkyl group, including those having a substituent, a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, 1-methylbutyl group And unsubstituted alkyl groups such as n-pentyl group and n-hexyl group; substituted alkyl groups such as 2-hydroxyethyl group, 2-methoxyethyl group, 2-cyanoethyl group and trifluoromethyl group;

  Examples of the cycloalkyl group include monocyclic or multicyclic cycloalkyl groups having 5 to 12 carbon atoms. The cycloalkyl group may have a substituent. 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 do. As the cycloalkyl group, including those having a substituent, an unsubstituted cycloalkyl group such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, and a cyclododecyl group; 1-isopropylcyclohexyl group, 2 , 3-dimethylcyclohexyl group, 2,5-dimethylcyclohexyl group, 2,6-dimethylcyclohexyl group, 3,4-dimethylcyclohexyl group, 3,5-dimethylcyclohexyl group, 2,4,6-trimethylcyclohexyl group, 3 , 3,5-trimethylcyclohexyl group, 1-isopropylcyclohexyl group, 2,6-diisopropylcyclohexyl group, 4-tert-butylcyclohexyl group, 3-tert-butylcyclohexyl group and other substituted cycloalkyl groups; That.

From the viewpoint of the color developability of the recorded image and the ease of synthesis of the compound represented by the general formula (2), it is preferable that two R ₁ are the same group.

  In general formula (2), M represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium each independently. Specific examples of the alkali metal include lithium, sodium, and potassium. Specific examples of organic ammonium include acetamide, benzamide, trimethylamino, butylamino, diethylamino, phenylamino, triethanolamino and the like. In the present invention, it is preferable that all M is sodium.

(Coloring material content)
The content (% by mass) of the first color material in the ink is preferably 0.01% by mass or more and 10.00% by mass or less based on the total mass of the ink. The content (% by mass) of the second color material in the ink is preferably 0.01% by mass or more and 10.00% by mass or less based on the total mass of the ink. Further, the total content of the first color material and the second color material in the ink is not particularly limited as long as it satisfies the reliability as an inkjet ink such as ejection characteristics. The total content (% by mass) of the first color material and the second color material in the ink is preferably 0.01% by mass or more and 10.00% by mass or less.

  The content B (mass%) of the second color material based on the total mass of the ink is a mass ratio with respect to the content A (mass%) of the first color material, and is 0.05 times or more and 9.00 times. The following is preferable. That is, “second colorant content B (mass%)” / “first colorant content A (mass%)” = 0.05 times or more and 9.00 times or less is preferable. If the mass ratio is less than 0.05 times, the color developability of the image may be insufficient. On the other hand, if the mass ratio is more than 9.00 times, the moisture resistance of the image may be insufficient.

(Aqueous medium)
The ink of the present invention may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. The ink of the present invention 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 monovalent or polyhydric alcohols, alkylene glycols, glycol ethers, nitrogen-containing polar compounds, sulfur-containing polar compounds, 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.

(Additive)
In the ink of the present invention, in addition to the above components, water-soluble organic compounds that are solid at room temperature, such as polyhydric alcohols such as trimethylolpropane and trimethylolethane; urea derivatives such as urea and ethyleneurea, as necessary May be included. Furthermore, in the ink of the present invention, a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, an evaporation accelerator, a chelating agent, and You may contain various additives, such as water-soluble resin.

(Ink physical properties)
The surface tension of the ink of the present invention at 25 ° C. is preferably 10 mN / m or more and 60 mN / m or less, more preferably 20 mN / m or more and 60 mN / m or less, and 30 mN / m or more and 40 mN / m or less. It is particularly preferred. By making the surface tension of the ink within the above-mentioned range, it is possible to effectively suppress the occurrence of ejection stagnation (displacement of ink landing point) due to wetting in the vicinity of the ejection port when applied to the ink jet system. . The surface tension of the ink can be adjusted by appropriately setting the content of a surfactant, a water-soluble organic solvent, or the like in the ink. In addition, it is preferable to adjust the viscosity of the ink so that good discharge characteristics can be obtained when discharging from the discharge port of the ink jet recording head. The viscosity of the ink of the present invention at 25 ° C. is preferably 1.0 mPa · s to 5.0 mPa · s, and more preferably 1.0 mPa · s to 3.0 mPa · s.

(Other inks)
In order to record a full-color image or the like, the ink of the present invention can be used in combination with another ink having a hue different from the ink of the present invention. Examples of the other ink include at least one ink selected from the group consisting of black ink, cyan ink, yellow ink, red ink, green ink, and blue ink. The color material used for other inks may be a known dye or a newly synthesized dye.

<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 Exemplified Compounds 1 to 4 and Comparative Compound 1>
With reference to the description in Patent Document 2, Exemplified Compounds 1 and 2 represented by the structural formulas shown below as free acid forms were synthesized. Thereafter, ion exchange was performed according to a conventional method to obtain sodium salt type compounds (these compounds are referred to as “compound A” and “compound B”). In addition, referring to the description in Patent Document 3, Exemplified Compounds 3 and 4 represented by the structural formulas shown below as free acid types were synthesized. Thereafter, ion exchange was performed according to a conventional method to obtain sodium salt type compounds (these compounds are referred to as “compound C” and “compound D”). Furthermore, with reference to the description in Patent Document 1, a comparative compound 1 represented by the structural formula shown below as a free acid form was synthesized. Thereafter, ion exchange was performed according to a conventional method to obtain a sodium salt type compound (this compound is referred to as “Compound E”).

<Preparation of ink>
Each component (unit:%) shown in the upper part of Table 2 was mixed and stirred sufficiently, and each ink was prepared by pressure filtration with a filter (manufactured by Fuji Film) having a pore size of 0.20 μm. “Acetyleneol E100” in Table 2 is a trade name of a nonionic surfactant (manufactured by Kawaken Fine Chemicals). The lower part of Table 2 shows the content A (%) of the first color material in the ink, the content B (%) of the second color material, and the “value of B / A (times)”. .

<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 22.4 ng of ink to a unit area of 1/600 inch × 1/600 inch is defined as “recording duty is 100%”. The color of the image was measured using a spectrophotometer (trade name “Spectrolino”, 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 ^*. In the present invention, “A” and “B” are acceptable levels and “C” is unacceptable levels in the evaluation criteria for each item shown below. The evaluation results are shown in Table 3.

(Color development)
Using the inkjet recording device described above, the recording duty is set on the recording medium (glossy paper, product name “Canon Photo Paper / Glossy Pro [Platinum Grade]”, manufactured by Canon) in an environment of a temperature of 23 ° C. and a relative humidity of 55%. A solid image of 100% was recorded to obtain a recorded matter. The optical density of the solid image was measured, and the color developability of the image was evaluated according to the following evaluation criteria.
A: The optical density was 1.80 or more.
B: The optical density was 1.40 or more and less than 1.80.
C: The optical density was less than 1.40.

(Moisture resistance)
Using the inkjet recording device described above, the recording duty is set on the recording medium (glossy paper, product name “Canon Photo Paper / Glossy Pro [Platinum Grade]”, manufactured by Canon) in an environment of a temperature of 23 ° C. and a relative humidity of 55%. A solid image of 100% was recorded to obtain a recorded matter. The obtained recorded matter was dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and then L ^* , a ^*, and b ^* were measured (L ₁ ^* , a ₁ ^*, and b ₁ ^* ). ). Next, the recorded material was placed in a thermostat set at a temperature of 25 ° C. and a relative humidity of 85% for one week, and then L ^* , a ^* and b ^* were measured (L ₂ ^* , a ₂ ^* and b ₂ ^* and To do). Then, the color change ΔE is calculated based on the equation: ΔE = {(L ₂ ^* −L ₁ ^* ) ² + (a ₂ ^* −a ₁ ^* ) ² (b ₂ ^* −b ₁ ^* ) ² } ^1/2 The moisture resistance of the images was evaluated according to the evaluation criteria shown below.
A: ΔE was less than 5.
B: ΔE was 5 or more and less than 7.
C: ΔE was 7 or more.

Claims (5)

An ink-jet ink containing a first color material and a second color material,
The first colorant is a compound represented by the following general formula (1):
The ink, wherein the second color material is a compound represented by the following general formula (2).

(In the general formula (1), each R ₁ independently represents a hydrogen atom, an alkyl group, a hydroxyalkyl group, a cycloalkyl group, a monoalkylaminoalkyl group, or a dialkylaminoalkyl group, and each R ₂ independently represents Represents a group represented by any of the following formulas (i) to (iv), X represents a linking group, and M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium.

(In the formulas (i) and (ii), M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium. In the formula (iv), R ₃ represents a hydrogen atom, an alkyl group, or an alkoxy group. Represents a group)

(In the general formula (2), each R ₁ independently represents an alkyl group or a cycloalkyl group, and each M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium)   The second colorant content B (% by mass) based on the total mass of the ink is 0.05 times or more in terms of a mass ratio with respect to the first colorant content A (% by mass). The ink according to claim 1, wherein the ink is 00 times or less. The ink according to claim 1 or 2, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (3).

(In the general formula (3), each M independently represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium) 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 3.

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