JP2007217525A - Magenta ink for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart excellent preservation stability, sufficient jetting stability even during long-term service and bright color-developability to magenta ink for inkjet recording and to impart good light resistance and ozone resistance to recorded matter using the same. <P>SOLUTION: As a colorant of the magenta ink for inkjet recording comprising at least a colorant, water and a water-soluble organic solvent, a dye (1) represented by general formula (1) and C. I. Acid Red 52 as a dye (2) are jointly used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magenta ink for inkjet recording.

  A magenta ink is required to form a full-color image using the ink jet recording method. As an example of a general magenta dye used for the ink, relatively good jetting stability and color developability are imparted to the ink. C. which is a monoazoxanthene dye that can be produced. I. Acid Red 14 and C.I., a disazo dye that can impart relatively good jetting stability to ink. I. Direct Red 227 (Patent Document 1) and the like are known.

  By the way, in recent years, as a required characteristic for ink jet recording ink, it is not only necessary to show good jetting stability and color developability, but also a high level of light resistance and resistance to active gases such as ozone have been required. C. I. Acid Red 14 and C.I. I. Direct Red 227 is no exception.

JP 2000-95983 A

  However, the above-mentioned magenta dye C.I. I. Acid Red 14 and C.I. I. Direct Red 227 cannot be said to have sufficient light resistance and ozone resistance, and an inkjet recording image created using magenta ink for inkjet recording containing these dyes cannot be ignored even in a normal storage state. It was a level.

  As described above, among magenta dyes used in general magenta inks for ink jet recording, C.I. I. As in Acid Red 14, a color having a relatively good color developability, that is, a hue suitable for obtaining a wide range of blended colors and a vivid color tends to have a relatively low light resistance level and ozone resistance level. .

  On the other hand, such as 1-alkyl-3-alkyl or aryl-4-cyano-pyrazol-5-ylazo dyes disclosed in British Patent 1,566,985, light resistance and active gas resistance Although magenta dyes are known to be relatively good, they use heavy metal cyanides for their production, which is not only a problem for waste disposal, but also a hue that is insufficient to produce a wide range of blended colors. In addition, there is a problem that a problem easily occurs in contact with various members used in the ink jet recording apparatus. Therefore, an ink jet printer equipped with a magenta ink for ink jet recording using a magenta dye having relatively good light resistance and active gas resistance has a problem in terms of ejection stability during long-term use.

  The present invention is superior in storage stability to magenta ink for ink-jet recording, maintains sufficient jetting stability even during long-term use, has vivid color developability, and has good light resistance to recorded matter using it. It aims at making it possible to give and ozone resistance.

  The present inventors have developed a specific pyrazolyl azopyridine (or pyrazolyl azopyrazine) -based dye that is excellent in light resistance and ozone resistance, although it is poor in color developability and jetting stability. C. having a specific xanthene structure, which has poor color development and jetting stability, although it is poor in ozone resistance. I. By using Acid Red 52 in combination as a magenta dye for magenta ink for ink jet recording, the good properties of both are not impaired, and each characteristic is not an arithmetic average intermediate level. In addition, the inventors have found that the respective good characteristics are maintained, and have completed the present invention.

  That is, the present invention relates to a magenta ink for inkjet recording containing at least a colorant, water and a water-soluble organic solvent, and the colorant is represented by the general formula (1)

(In General Formula (1), R ₁ represents a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted aryl group. R ₂ represents a hydrogen atom, a halogen atom, or a cyano group. R ₃ Represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group or an optionally substituted heterocyclic group, wherein R ₄ , R ₅ , R ₆ and R ₇ are each independently hydrogen An atom, an alkyl group that may be substituted, an aryl group that may be substituted, a heterocyclic group that may be substituted, a sulfonyl group that may be substituted, or an acyl group that may be substituted, provided that R ₄ and R ₅ is not both a hydrogen atom, and R ₆ and R ₇ are not both hydrogen atoms, A ₁ and A ₂ are both carbon atoms that may be substituted, or Even if one of these is substituted Is a have carbon atom, and the other is a nitrogen atom.)
As dye (1) and C.I. I. The present invention provides a magenta ink for ink-jet recording characterized by containing Acid Red 52.

  The magenta ink for ink jet recording of the present invention includes a specific pyrazolyl azopyridine (or pyrazolyl azopyrazine) dye and a C.I. I. Since Acid Red 52 is used in combination as a magenta dye for magenta ink for ink jet recording, good color developability, jetting stability, light resistance and ozone resistance can be imparted to the obtained ink jet recorded matter.

  The magenta ink for ink-jet recording of the present invention includes C.I. dyes (1) and (2) represented by the above general formula (1) as water, a water-soluble organic solvent and a colorant. I. Acid Red 52 is contained. Below, the characteristic of each dye itself and the effect of those combined use are demonstrated.

  The dye (1) represented by the general formula (1) has excellent light resistance and ozone resistance. However, on the other hand, it has a weak point that it is inferior in color development and vividness. For this reason, when the dye (1) is used alone as the magenta dye of the magenta ink for ink jet recording, it is difficult to secure a sufficient color reproduction range, and it is also difficult to form a high color image. Further, the dye (1) may cause a problem due to contact with some members used in the ink jet recording apparatus. For example, there is a high possibility of attacking metal parts, piezoelectric elements, water-repellent films, and adhesives that adhere them, etc. that constitute an ink jet head. It may cause problems such as foreign matter adhesion. Such aggressiveness against various materials may cause not only a decrease in continuous injection stability but also a decrease in long-term injection stability. Further, when a relatively large amount of the dye (1) is contained in the magenta ink for ink jet recording, there is a concern that the frequency of generating bubbles in the ink flow path leading to the ink jet head and the ink jet head is increased. From this point as well, there is a concern about a decrease in injection stability.

  On the other hand, the C.I. I. Unlike the dye (1), Acid Red 52 has poor light resistance and ozone resistance, but has excellent sharpness and color development. In addition, C.I. I. Acid Red 52 is less aggressive against various members used in the ink jet recording apparatus. Rather, some members (for example, rubber members such as rubber caps and wiper rubber) are made of magenta ink for ink jet recording. Shows the ability to reduce aggression.

  In general, when two types of dyes having different properties are used in combination, the good properties of the two may be impaired, or even if they are not impaired, each property may be an arithmetic average intermediate level. Of the dye (1) and the dye (2). I. When the acid red 52 is used in combination, it is possible to obtain an effect that the respective good characteristics are unexpectedly maintained.

  The magenta ink for inkjet recording of the present invention contains the dye (1) and the dye (2) in a weight ratio, preferably 7: 3 to 9: 1, more preferably 8: 2 to 9: 1. To do. By making it within this range, the excellent properties of each dye can be exhibited in a well-balanced manner.

  Further, the total content of the dye (1) and the dye (2) in the magenta ink for inkjet recording is appropriately determined depending on the performance and required characteristics of the ink, but is preferably relative to the total amount of magenta ink for inkjet recording. 1 to 5% by weight, more preferably 2 to 4% by weight. In addition, within the range which does not impair the effect of this invention, it is C. of dye (1) and dye (2). I. In addition to Acid Red 52, other dyes can be used in combination.

Next, the substituents R _{1 to} R ₇ and A _{1 to} A _{2 in} the general formula of the dye (1) will be described.

As described above, R ₁ represents a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted aryl group. R ₂ represents a hydrogen atom, a halogen atom or a cyano group. R ₃ represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group or an optionally substituted heterocyclic group. R ₄ , R ₅ , R ₆ and R ₇ are each independently a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted heterocyclic group, or optionally substituted. Represents a sulfonyl group or an optionally substituted acyl group. However, R ₄ and R ₅ are not both hydrogen atoms, and R ₆ and R ₇ are not both hydrogen atoms. Each of A ₁ and A ₂ is a carbon atom that may be substituted, or one of these is a carbon atom that may be substituted, and the other is a nitrogen atom.

  As a halogen atom in General formula (1), a fluorine atom, a chlorine atom, a bromine atom, etc. are mentioned.

  In the general formula (1), the alkyl group in the alkyl group which may be substituted is preferably an alkyl group having 1 to 6 carbon atoms, and examples of the substituent include a hydroxyl group, an alkoxy group (methoxy group, Ethoxy group, etc.), cyano group, halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), ionic hydrophilic group (carboxylate, sulfonate, etc.). Specific examples of the alkyl group which may be substituted include methyl group, ethyl group, n-butyl group, isopropyl group, tert-butyl group, hydroxyethyl group, methoxyethyl group, cyanoethyl group, trifluoromethyl group, 3- Examples include a sulfopropyl group and a 4-sulfobutyl group.

  In the general formula (1), the aryl group in the optionally substituted aryl group is preferably an aryl group having 6 to 12 carbon atoms excluding the carbon atoms of the substituent. Examples of substituents include alkyl groups (methyl group, ethyl group, isopropyl group, tert-butyl group, n-octyl group, etc.), alkoxy groups (see above), halogen atoms (see above), alkylamino groups (methyl). Amino group, dimethylamino group, etc.), amide group, carbamoyl group, sulfamoyl group, sulfoamide group, hydroxyl group, ester group (methoxycarbonyl group, ethoxycarbonyl group etc.) and ionic hydrophilic group (see above). Specific examples of the aryl group which may be substituted include phenyl group, naphthyl group, p-tolyl group, p-octylphenyl group, mesityl group, p-methoxyphenyl group, o-chlorophenyl group and m- (3-sulfo group. Propylamino) phenyl group and the like.

  In the general formula (1), the heterocyclic group in the optionally substituted heterocyclic group is preferably a 5-membered or 6-membered heterocyclic group. Examples of the substituent include an amide group, a carbamoyl group, a sulfamoyl group, a sulfoamide group, a hydroxyl group, an ester group (see above), and an ionic hydrophilic group (see above). Specific examples of the heterocyclic group which may be substituted include 2-pyridyl group, 2-thienyl group, 2-thiazolyl group, 2-benzothiazolyl group, 2-furyl group, 6-sulfobenzothiazolyl group and 6 -Sulfonate benzothiazolyl group etc.).

  In the general formula (1), examples of the substituent of the sulfonyl group which may be substituted include an alkyl group (see above) and an aryl group (see above). Specific examples of the sulfonyl group which may be substituted include a methylsulfonyl group and a phenylsulfonyl group.

  In the general formula (1), the acyl group of the acyl group which may be substituted is preferably an acyl group having 1 to 12 carbon atoms excluding the carbon atoms of the substituent. Examples of the substituent include an ionic hydrophilic group (see above). Specific examples of the acyl group that may be substituted include an acetyl group, a benzoyl group, and a chloroacetyl group.

In the general formula (1), as described above, A ₁ and A ₂ are both carbon atoms that may be substituted, or carbon atoms that one of these may be substituted. The other is a nitrogen atom. A case in which both A ₁ and A ₂ are carbon atoms is preferable in that a more excellent performance can be exhibited. Examples of the substituent bonded to a carbon atom of A ₁ and A _2, an alkyl group having 1 to 3 carbon atoms, a carboxyl group, a carbamoyl group and cyano group.

In general formula (1), R ₄ and R ₅ are not both hydrogen atoms, and R ₆ and R ₇ are not both hydrogen atoms. Moreover, since there exists a tendency for the water solubility of dye (1) to improve when the number of substitution of a sulfonic acid group or a carboxyl group increases, it is preferable to adjust those substitution numbers as needed.

As a preferred embodiment of the dye (1), in the general formula (1), R ₁ is an alkyl group, R ₂ is a cyano group, R ₃ is a hydrogen atom or an optionally substituted heterocyclic group, R ₄ is a hydrogen atom, An optionally substituted heterocyclic group or a substituted aryl group, R ₅ and R ₆ are substituted heterocyclic groups or a substituted aryl group, R ₇ is a hydrogen atom, and A ₁ is substituted. And an embodiment in which A ₂ is an optionally substituted carbon atom.

As a more preferred embodiment of the dye (1), in the general formula (1), R ₁ is substituted with a tert-butyl group, R ₂ is a cyano group, R ₃ is substituted with a hydrogen atom or a sulfonic acid group or an alkali metal base thereof. Benzothiazolyl group (preferably benzothiazol-2-yl group), benzothiazolyl group (preferably benzothiazol-2-yl group) R ₄ may be substituted with a hydrogen atom, a sulfonic acid group or an alkali metal base thereof, or A trialkylphenyl group (preferably a mesityl group) substituted with a sulfonic acid group or an alkali metal base thereof, and R ₅ and R ₆ are each independently mono- or mono-substituted or optionally substituted with a sulfonic acid group or an alkali metal base thereof A trialkylphenyl group (preferably a p-octylphenyl group or a mesityl group) or Sulfonic acid group or alkali metal base in a benzothiazolyl group substituted (preferably benzothiazol-2-yl group), R ₇ is a hydrogen atom, A ₁ is an alkyl group (preferably methyl group) substituted with In this embodiment, A ₂ is a carbon atom that may be substituted with a cyano group.

  Preferable specific examples of the dye (1) include compounds represented by the following chemical formulas (1-A) to (1-E).

The compound represented by the chemical formula (1-A) is represented by the general formula (1), in which R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ is a benzothiazol-2-yl group, and R ₄ is a hydrogen atom. , R ₅ and R ₆ are p-octylphenyl groups, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom substituted with a cyano group. is there.

In the compound represented by the chemical formula (1-B), in general formula (1), R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are benzothiazol-2-yl groups, R ₅ And R ₆ is a mesityl group, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom.

The compound represented by the chemical formula (1-C) is represented by the following general formula (1): R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are 6-sulfo sodium salts benzothiazole-2- An yl group, R ₅ and R ₆ are 3-sulfo sodium salt-mesityl groups, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom.

In the compound represented by the chemical formula (1-D), R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are hydrogen atoms, and R ₅ and R ₆ are mesityl in the general formula (1). In this embodiment, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom.

The compound represented by the chemical formula (1-E) is represented by the following general formula (1): R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are 6-sulfo potassium salts benzothiazole-2- An yl group, R ₅ and R ₆ are 3-sulfopotassium salt-mesityl groups, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom.

  The dye (1) represented by the general formula (1) can be produced according to steps (a) to (c) described below.

Step (a)
A diazonium salt is formed by reacting the aminopyrazole represented by the chemical formula (1a) with a diazotizing agent. As the diazotizing agent, a dilute hydrochloric acid aqueous solution of sodium nitrite can be preferably used. Isopentyl nitrite and nitrosyl sulfuric acid can also be used.

The substituents R ₁ and R ₂ in the chemical formula (1a) are as described in the dye (1). In addition, chemical formula (1a) aminopyrazole is a method described in US Pat. No. 3,336,285, Heterocycles, 20,519 (1983), Japanese Patent Publication No. 6-19036, and the like. Can be synthesized.

Step (b)
Next, the diazonium salt formed in the step (a) is reacted with a coupling agent represented by the chemical formula (1b) to form a compound represented by the chemical formula (1c).

The substituents R _{1 to} R ₇ in the chemical formulas (1b) and (1c) are as described for the dye (1). The pyridine coupling agent of the chemical formula (1c) can be synthesized by the method described in JP-A-51-83631, JP-A-49-74718, JP-B-52-46230, etc. .

Step (c)
Next, by reacting the compound formed in step (b) with an alkylating agent, an arylating agent or a heterylating agent in the presence of a base, the dye (1) represented by the general formula (1) is obtained. can get. Examples of the base used in this step include organic bases such as diisopropylethylamine; inorganic bases such as potassium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium hydroxide, and potassium hydroxide. The alkylating agent is a compound represented by “RX”. Here, R is an optionally substituted alkyl group. X is a halogen atom or OSO ₂ R ′, and R ′ is an aryl group such as an alkyl group or a phenyl group. The arylating agent is a compound represented by “Ar-X”. Here, Ar is a phenyl group substituted with an electron-withdrawing group (preferably substituted with a substituent having a total Hammett's σp value of 0.2 or more). A heterylating agent is a compound represented by “Het-X”. Here, Het is preferably a heterocycle such as a 2-pyridyl group, 2-thienyl group, 2-thiazolyl group, 2-benzothiazolyl group, triazyl group, 2-furyl group and the like.

In addition, it is C. of dye (2). I. For Acid Red 52, a commercially available dye can be used. Here, the dye (2). I. The acid red 52 is, for example, a dye represented by the general formula (2).

  Next, water and a water-soluble organic solvent constituting the magenta ink for inkjet recording of the present invention will be described.

  As the water used in the present invention, ion-exchanged water with less salts is preferable. Since the content of water in the magenta ink for ink jet recording is positioned as the balance of other components, it depends on the content of other components, but is usually 10 to 90% by weight, preferably 40 to 80% by weight. It is.

  The water-soluble organic solvent used in the present invention mainly includes a wetting agent for preventing the ink from drying at the nozzle tip of the inkjet head and a penetrating agent for mainly increasing the drying speed on the paper surface. .

  Examples of the wetting agent for preventing ink drying include lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; dimethylformamide, Amides such as dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol , Dipropylene glycol, tripropylene glycol, thiodiglycol, hexylene glycol, etc. Glycol; glycerin; 2-pyrrolidone; N- methyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone. Among these, polyhydric alcohols such as alkylene glycol and glycerin are preferable.

  The blending amount of the wetting agent for preventing the ink from drying in the magenta ink for ink jet recording is generally 0 to 95% by weight, preferably 10 to 80% by weight, and more preferably 10 to 50% by weight.

  On the other hand, as a penetrant for increasing the drying speed on paper, for example, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, triethylene glycol Methyl ether, triethylene glycol ethyl ether, triethylene glycol propyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, tripropylene Glycol methyl ether, trip Propylene glycol ethyl ether, glycol ethers such as tripropylene glycol propyl ether.

  In the magenta ink for ink jet recording, the blending amount of the penetrant for increasing the drying speed is generally 0 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 1 to 10% by weight. . It should be noted that if the blending amount is excessive, the permeability of the ink to the paper becomes too high, which may cause bleeding.

  The magenta ink for ink-jet recording of the present invention further contains conventionally known additives such as viscosity modifiers such as polyvinyl alcohol, cellulose and water-soluble resins; surface tension modifiers; Also good.

  The magenta ink for ink-jet recording of the present invention includes C.I. of the above-mentioned dye (1) and dye (2). I. It can be prepared by uniformly mixing a colorant containing Acid Red 52, water, a water-soluble organic solvent, and various other additives as required according to a conventional method.

Examples 1-7 and Comparative Examples 1-6
A magenta ink for inkjet recording was prepared by uniformly mixing the ink composition components shown in Table 1. Here, the dyes (1-A) to (1-E) correspond to the compounds represented by the chemical formulas (1-A) to (1-E), respectively.

  For the obtained magenta ink for ink-jet recording, (a) jetting stability evaluation, (b) color development evaluation, (c) ozone resistance evaluation, (d) light resistance evaluation and (e) comprehensive evaluation are as follows. went.

  First, a desired ink cartridge was filled with magenta ink for ink jet recording, and the ink cartridge was mounted on a digital multi-function peripheral equipped with an ink jet printer (manufactured by Brother Industries, Ltd .; DCP-110C) to evaluate printing. Samples for (b) color development evaluation, (c) ozone resistance evaluation, and (d) light resistance evaluation include glossy paper (manufactured by Brother Industries, Ltd .; photographic glossy paper (model number: BP60GLA)) and magenta ink. A gradation sample was printed and a patch with an initial OD value of 1.0 was used.

(A) Evaluation of ejection stability Continuous printing evaluation of 100 million dots (about 30,000 sheets) was performed, and evaluation was performed according to the following criteria. The obtained results are shown in Table 1.
Evaluation criteria for jetting stability ◎ ... No ejection and no bending during continuous printing.
○: During continuous printing, there is a slight non-ejection or ejection bending. Both non-discharge or discharge bend is recovered by purging within 5 times.
×… There are many non-ejections and ejection bends during continuous printing. Both non-discharge and discharge bend do not recover in a short time.

(B) Color development evaluation The above-described gradation sample was evaluated based on the following evaluation criteria as to whether or not the magenta color was sufficiently expressed by visual observation. The obtained results are shown in Table 1.
Evaluation criteria for color development ○: Magenta color is sufficiently expressed ×: Magenta color expression is insufficient

(C) Ozone resistance evaluation An ozone resistance test was performed using the gradation sample described above. The ozone resistance test was performed using an ozone weather meter OMS-H manufactured by Suga Test Instruments Co., Ltd., and left for 40 hours at an ozone concentration of 1 ppm, a bath temperature of 24 ° C., and a humidity of 60% RH. For the magenta color patch showing an OD value of 1.0 before the test, the OD value before and after the ozone resistance test was measured. The OD value was measured by Spectrolino (light source: D ₆₅ ; field of view: 2 °; Status A) manufactured by Gretag Macbeth. From the following formula I, the patch having an OD value of 1.0 before the test was determined as the ozone resistance OD value reduction rate. The obtained ozone resistance OD value reduction rate was evaluated based on the following evaluation criteria. The obtained results are shown in Table 1.

耐オゾン性評価基準
◎…耐オゾン性ＯＤ値減少率が２０％未満
○…耐オゾン性ＯＤ値減少率が２０％以上３０％未満
△…耐オゾン性ＯＤ値減少率が３０％以上４０％未満
×…耐オゾン性ＯＤ値減少率が４０％以上

Ozone resistance evaluation criteria ◎… Ozone resistance OD value decrease rate is less than 20% ○… Ozone resistance OD value decrease rate is 20% or more and less than 30% △… Ozone resistance OD value decrease rate is 30% or more and less than 40% ×: Ozone-resistant OD value reduction rate is 40% or more

(D) Light resistance evaluation The light resistance test was done using the gradation sample mentioned above. The light resistance test was performed using a strong energy xenon weather meter SC750-WN manufactured by Suga Test Instruments Co., Ltd. Xenon lamp light was used as a light source, and irradiation was performed at room temperature of 25 ° C., humidity of 50% RH, and illuminance of 93000 Lux for 100 hours. About the magenta color patch which shows OD value 1.0 before a test, the OD value after a light resistance test was measured. The OD value was measured by Spectrolino (light source: D ₆₅ ; field of view: 2 °; Status A) manufactured by Gretag Macbeth. From the following formula II, the light resistance OD value reduction rate was determined for a patch having an OD value of 1.0 before the test. The obtained light resistance OD value reduction rate was evaluated based on the following evaluation criteria. The obtained results are shown in Table 1.

Light resistance evaluation criteria ◎… Light resistance OD value decrease rate is less than 20% ○… Light resistance OD value decrease rate is 20% or more and less than 30% △… Light resistance OD value decrease rate is 30% or more and less than 40% ×… Light resistance OD value reduction rate is 40% or more

(E) Comprehensive evaluation For each ink, comprehensive evaluation was performed according to the following evaluation criteria from the above results. The obtained results are shown in Table 1.
Overall evaluation criteria G: All evaluation results are ◎ or ○ NG: Some of the evaluation results have Δ or ×

  From the results in Table 1, the knowledge obtained for each of the examples and comparative examples is as follows.

  Example 1 (total dye content 3%): 5% of the dye (2) that can be used without any problem for the member and has good color development is contained in the total amount of the dye, so that the ink is stable. In addition, the color was good. Since 95% of the dye (1-B) having good ozone resistance and light resistance was contained in the whole dye, the ozone resistance and light resistance were good.

  Example 2 (Total dye content 3%): The ink is stable because it contains 10% of the dye (2) that can be used without problems with the member and has good color development. In addition, the color was good. Since 90% of the dye (1-A) having good ozone resistance and light resistance was contained with respect to the whole dye, the ozone resistance and light resistance were good.

  Example 3 (Total dye content: 3%): The ink is stable because it contains 20% of the dye (2) that can be used without problems with the member and has good color development. In addition, the color was good. Since 80% of the dye (1-B) having good ozone resistance and light resistance was contained with respect to the whole dye, the ozone resistance and light resistance were good.

  Example 4 (Total dye content 3%): 30% of the dye (2), which can be used without any problem for the member and has good color development, is contained in the total amount of the dye, so that the ink is stable. In addition, the color was good. Since 70% of the dye (1-C) having good ozone resistance and light resistance was contained with respect to the whole dye, the ozone resistance and light resistance were good.

  Example 5 (Total dye content: 3%): The ink is stable because it contains 40% of the dye (2) that can be used without problems with the member and has good color development. In addition, the color was good. Since the dye (1-B) having good ozone resistance and light resistance is 60% of the whole dye, the ozone resistance and light resistance were good, but the inclusion of the dye (1-B) Since the ratio was somewhat small, ozone resistance and light resistance were somewhat worse than those of Examples 1-4, 6 and 7.

  Example 6 (Dye total content 2%): The ink is stable because it contains 20% of the dye (2) that can be used without problems with the member and has good color development. In addition, the color was good. Since 80% of the dye (1-D) having good ozone resistance and light resistance was contained with respect to the whole dye, the ozone resistance and light resistance were good.

  Example 7 (total dye content: 4%): The ink is stable because it contains 20% of the dye (2) that can be used without any problem for the member and has good color development. In addition, the color was good. Since 80% of the dye (1-E) having good ozone resistance and light resistance was contained with respect to the whole dye, the ozone resistance and light resistance were good.

  Comparative Example 1 (Total Dye Content 3%): Since the dye used was only the dye (1-A), ozone resistance and light resistance were good, but there was a problem in jetting stability. In addition, color development was insufficient.

  Comparative Example 2 (Total dye content 3%): C.I. I. Since 20% of Acid Red 14 was contained with respect to the whole dye, the ink could be stably ejected and the color development was good. However, C.I. I. Since Acid Red 14 has poor ozone resistance and light resistance, ozone resistance and light resistance were insufficient even when mixed with the dye (1-C).

  Comparative Example 3 (Total Dye Content 3%): C. which can be used without problems for members. I. Since the direct red 227 is contained in an amount of 20% with respect to the entire dye, the ink could be stably ejected. However, C.I. I. Since Direct Red 227 was contained in an amount of 20% based on the whole dye, color development was insufficient. In addition, C.I. I. Since Direct Red 227 has poor ozone resistance and light resistance, ozone resistance and light resistance were insufficient even when mixed with dye (1-D).

  Comparative Example 4 (Total Dye Content 3%): Since the dye used was only the dye (2), the ink could be stably ejected and the color development was good. However, since the dye (2) has poor ozone resistance and light resistance, the ozone resistance and light resistance were insufficient.

  Comparative Example 5 (Total dye content 3%): The dye used was C.I. I. Since only Acid Red 14 was used, ink could be stably ejected and color development was also good. However, C.I. I. Since Acid Red 14 had poor ozone resistance and light resistance, ozone resistance and light resistance were insufficient.

  Comparative Example 6 (Total dye content 3%): The dye used was C.I. I. Since only Direct Red 227 was used, ink could be ejected stably. However, C.I. I. Since Direct Red 227 has poor color development, ozone resistance, and light resistance, color development, ozone resistance, and light resistance were insufficient.

According to the present invention, with respect to magenta ink for ink jet recording, it has excellent storage stability, maintains sufficient jetting stability even in long-term use, has vivid color developability, and is good for recorded matter using it. Light resistance and ozone resistance can be imparted.

Claims (11)

In a magenta ink for inkjet recording containing at least a colorant, water, and a water-soluble organic solvent, the colorant is represented by the general formula (1)

(In General Formula (1), R ₁ represents a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted aryl group. R ₂ represents a hydrogen atom, a halogen atom, or a cyano group. R ₃ Represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aryl group or an optionally substituted heterocyclic group, wherein R ₄ , R ₅ , R ₆ and R ₇ are each independently hydrogen An atom, an alkyl group that may be substituted, an aryl group that may be substituted, a heterocyclic group that may be substituted, a sulfonyl group that may be substituted, or an acyl group that may be substituted, provided that R ₄ and R ₅ is not both a hydrogen atom, and R ₆ and R ₇ are not both hydrogen atoms, A ₁ and A ₂ are both carbon atoms that may be substituted, or Even if one of these is substituted Is a have carbon atom, and the other is a nitrogen atom.)
As dye (1) and C.I. I. A magenta ink for ink-jet recording comprising Acid Red 52.   The magenta ink for ink-jet recording according to claim 1, comprising the dye (1) and the dye (2) in a weight ratio of 7: 3 to 9: 1.   The magenta ink for ink-jet recording according to claim 1 or 2, comprising the dye (1) and the dye (2) in a total amount of 1 to 5% by weight based on the total amount of the magenta ink for ink-jet recording. In the general formula (1), R ₁ is an alkyl group, R ₂ is a cyano group, R ₃ is a hydrogen atom or an optionally substituted heterocyclic group, R ₄ is a hydrogen atom, an optionally substituted heterocyclic group or a substituted group An aryl group, R ₅ and R ₆ are substituted heterocyclic groups or substituted aryl groups, R ₇ is a hydrogen atom, A ₁ is a substituted carbon atom, _The magenta ink for inkjet recording according to any one of claims 1 to 3, wherein ₂ is a carbon atom which may be substituted. In the general formula (1), R ₁ is a tert-butyl group, R ₃ is a hydrogen atom or a benzothiazolyl group which may be substituted with a sulfonic acid group or an alkali metal base thereof, R ₄ is a hydrogen atom or a sulfonic acid A benzothiazolyl group which may be substituted with a group or an alkali metal base thereof, or a sulfonic acid group or a trialkylphenyl group which is substituted with an alkali metal base thereof, and R ₅ and R ₆ are each independently a sulfonic acid group or a group thereof A mono- or trialkylphenyl group which may be substituted with an alkali metal base or a sulfonic acid group or a benzothiazolyl group substituted with the alkali metal base, and A ₁ is a carbon atom substituted with an alkyl group; Inkuji of ₂ claim 4, wherein the carbon atoms which may be substituted with a cyano group Magenta ink for jet recording. In the general formula (1), R ₃ is a hydrogen atom or a benzothiazol-2-yl group which may be substituted with a sulfonic acid group or an alkali metal base thereof, and R ₄ is a hydrogen atom, a sulfonic acid group or an alkali metal thereof. A benzothiazol-2-yl group optionally substituted with a base or a sulfonic acid group or a trimethylphenyl group substituted with an alkali metal base thereof, and R ₅ and R ₆ are each independently a sulfonic acid group or an alkali thereof A p-octylphenyl group or mesityl group which may be substituted with a metal base, or a benzothiazol-2-yl group substituted with a sulfonic acid group or an alkali metal base thereof, and A ₁ is substituted with a methyl group is a carbon atom, Inkuji of claim 5, wherein a ₂ is a carbon atoms which may be substituted with a cyano group Tsu bet recording magenta ink. In the general formula (1), R ₃ is a benzothiazol-2-yl group, R ₄ is a hydrogen atom, R ₅ and R ₆ are p-octylphenyl groups, and A ₂ is substituted with a cyano group. The magenta ink for ink jet recording according to claim 6, wherein the magenta ink is a carbon atom. The magenta for ink jet recording according to claim 6, wherein in the general formula (1), R ₃ and R ₄ are benzothiazol-2-yl groups, R ₅ and R ₆ are mesityl groups, and A ₂ is a carbon atom. ink. In the general formula (1), R ₃ and R ₄ are 6-sulfo sodium salt benzothiazol-2-yl groups, R ₅ and R ₆ are 3-sulfo sodium salt mesityl groups, and A ₂ is a carbon atom. The magenta ink for inkjet recording according to claim 6. The magenta ink for ink jet recording according to claim 6, wherein, in the general formula (1), R ₃ and R ₄ are hydrogen atoms, R ₅ and R ₆ are mesityl groups, and A ₂ is a carbon atom. In the general formula (1), R ₃ and R ₄ are 6-sulfo potassium salt benzothiazol-2-yl groups, R ₅ and R ₆ are 3-sulfo potassium salt-mesityl groups, and A ₂ is a carbon atom. The magenta ink for ink jet recording according to claim 6.