JP4630584B2 - Ink and inkjet recording ink - Google Patents

Description

  The present invention relates to an ink containing a dye having a specific physical property value and a method for improving the solution stability of the dye.

In recent years, a material for forming a color image has been mainly used as an image recording material. Specifically, an inkjet recording material, an electrophotographic recording material, a transfer type silver halide photosensitive material, a printing ink. Recording pens are actively used.
In these color image recording materials, in order to reproduce or record a full-color image, so-called additive color mixing and subtractive color mixing three primary colors (dyes and pigments) are used, but a preferable color reproduction range can be realized. The fact is that there is no fast dye that has absorption characteristics and can withstand various use conditions and environmental conditions, and improvement is strongly desired.

The ink jet recording method is rapidly spreading and further developing because of its low material cost, high speed recording, low noise during recording, and easy color recording.
Inkjet recording methods include a continuous method in which droplets are continuously ejected and an on-demand method in which droplets are ejected in accordance with image information signals. In the ejection method, liquid is applied by applying pressure with a piezo element. There are a method of ejecting droplets, a method of generating bubbles in ink by heat and ejecting droplets, a method of using ultrasonic waves, and a method of sucking and ejecting droplets by electrostatic force. As the ink for ink jet recording, water-based ink, oil-based ink, or solid (melted type) ink is used.

  For dyes used in such inks for ink jet recording, good solubility or dispersibility in solvents, high density recording, good hue, light, heat, environment Fast against active gases (NOx, ozone and other oxidizing gases, SOx, etc.), excellent fastness to water and chemicals, good fixability to image-receiving materials, and low bleeding. It is required to have excellent storage stability as an ink, no toxicity, high purity, and availability at low cost. However, it is extremely difficult to search for dyes that meet these requirements at a high level. In particular, an ink having a good black hue, robust against light, humidity and heat, a high molar extinction coefficient, high character quality in document printing, and porous white inorganic pigment particles When printing on an image receiving material having a receiving layer, it is strongly desired to be robust against oxidizing gases such as ozone in the environment.

Therefore, the dyes used in each of the above applications need to have the following properties in common. That is, it has favorable absorption characteristics in terms of color reproducibility, fastness under the environmental conditions used, for example, light resistance, heat resistance, moisture resistance, resistance to oxidizing gases such as ozone, and other chemical fastness such as sulfurous acid gas For example, the property is good and the molar extinction coefficient is large.
Conventionally, disazo dyes and trisazo dyes have been generally used as black dyes. Non-heterocyclic compounds such as phenol, naphthol, naphthylamine, and aniline are widely used as raw materials for these disazo dyes and trisazo dyes. As the disazo dyes obtained from these raw materials, the dyes disclosed in Patent Document 1, Patent Document 2, and the like are known, but all have the problem that light fastness is inferior, and oxidizing properties such as ozone. Fastness to gas is very poor.
In order to develop a colorant that is robust against oxidizing gases such as ozone, the present inventors have moved away from conventional raw materials such as phenol, naphthol, naphthylamine, and aniline, and mainly use heterocyclic compounds as raw materials. It came to the idea of doing. So far, disazo dyes and trisazo dyes containing two or more heterocycles have been described in Patent Document 3, Patent Document 4, Patent Document 5, etc., but these dyes are all used for dyeing fibers. It is a so-called dye that has been developed, and has the performance required in the present invention, that is, whether it has favorable absorption characteristics for color reproduction, and fastness (for example, light resistance, heat resistance, moisture resistance) under the used environmental conditions. In particular, there is no disclosure on the properties, particularly resistance to oxidizing gases such as ozone, which is a problem in ink jet image formation, and other chemical fastness properties such as sulfurous acid gas, and any structure is optimal for image formation of the present invention. It is completely unknown whether it is. In addition, the water-soluble dye disclosed in Patent Document 5 in which a water-soluble disazo dye containing two or more heterocycles is described has only two water-soluble groups, so it has low solubility in water. It was not suitable for inkjet applications.
European Patent No. 0761771 Japanese Patent No. 2716541 German Patent 2743097 JP 59-133259 A JP-A-52-76331

  An object of the present invention is to provide a colored image or coloring material having a good hue and excellent fastness, and for printing such as inkjet or writing as a stable ink with little change in physical properties even when stored for a long period of time. And providing a method for improving the solution stability.

Ｒ _5, はシアノ基、アルコキシカルボニル基、カルボキシル基又はカルバモイル基を表す。
Ｒ _6, およびＲ ₇ は、ハロゲン原子、脂肪族基、芳香族基、複素環基、アルコキシ基、及びアシルアミノ基よりなる群から選択される基で置換された芳香族基又は複素環基を表す。

上記一般式（１）中、Ｂ ₁ およびＢ ₂ は、各々＝ＣＲ ₁ −および−ＣＲ ₂ ＝を表す。
Ｒ ₁ およびＲ ₂ は、それぞれ独立して、水素原子、脂肪族基、またはシアノ基を表す。
Ｒ ₃ は、芳香族基を表し、該芳香族基は、スルホ基で置換されていてもよい。
Ｒ ₄ は、水素原子を表す。
Ｇは、スルホ基で置換されていてもよい、アニリノ基を表す。
２．下記安定性試験方法で染料の残存率が６０％以下のアゾ染料に、アゾ基に直結していない芳香環を共役π電子６個以上に相当する量増やすことによって、染料の残存率が向上したアゾ染料を少なくとも１種含むことを特徴とする上記１に記載のインク。
安定性試験方法：染料０．１ｍｍｏｌを水１０ｍｌに溶かし、ＮａＨＣＯ₃８４ｍｇを加えて、１時間加熱還流し、冷却後、分光光度計で染料の残存率を測定する。
３．アゾ染料が、水溶性ジスアゾまたはポリアゾ染料であることを特徴とする上記１または２に記載のインク。
４．アゾ染料が、下記物性１を有することを特徴とする上記１〜３のいずれか一項に記載のインク。
物性１：ＤＭＦ溶媒で測定した吸収スペクトルの最大吸収波長をλmax（ＤＭＦ）としたとき、６８０≧λmax（ＤＭＦ）≧５７０ｎｍである。
５．アゾ染料が下記物性２を有することを特徴とする上記１〜４のいずれか一項に記載のインク。
物性２：酸化電位が１．０Ｖ（ｖｓ ＳＣＥ）より貴である。
６．アゾ染料が下記物性３を有することを特徴とする上記１〜５のいずれか一項に記載のインク。
物性３：水溶媒で測定した吸収スペクトルの最大吸収波長をλmax（水）としたときに、｜λmax（ＤＭＦ）−λmax（水）｜≧３０ｎｍである。
７．アゾ染料が下記物性４を有することを特徴とする上記１〜６のいずれか一項に記載のインク。
物性４：ＤＭＦ溶媒でのモル吸光係数をε（ＤＭＦ）、水溶媒でのモル吸光係数をε（水）としたときに、ε（水）／ε（ＤＭＦ）≦０．９である。
８．アゾ染料が下記物性５を有することを特徴とする上記１〜７のいずれか一項に記載のインク。
物性５：λmax（水）を会合体の吸収極大波長、λmax（ＤＭＦ）をモノマーの吸収極大波長と定義するときに、水溶媒での吸収スペクトルにおいて会合体の吸収極大波長の吸光度をＡｂｓ（会合）、モノマーの吸収極大波長での吸光度をＡｂｓ（モノマー）としたときに、Ａｂｓ（モノマー）／Ａｂｓ（会合体）≦０．７５である。
９．アゾ染料が、含窒素６員環を含むことを特徴とする上記１〜８のいずれか一項に記載のインク。
１０．アゾ染料が、５員複素環を含むことを特徴とする上記１〜９のいずれか一項にインク。
１１．上記１〜１０のいずれか一項に記載のインクを用いたことを特徴とするインクジェット記録用インク。
尚、本発明は上記１〜１１に記載の構成を有するものであるが、以下、その他についても参考のため記載した。
The present inventors have studied in detail for a dye having a good hue, high fastness to light and ozone, and stable even after long-term storage in ink. It has been found that the above object can be achieved with a water-soluble azo dye.
That is, according to the present invention, an ink having the following constitution is provided to achieve the above object of the present invention.
1. An ink comprising at least one azo dye having a total of more than 12 aromatic conjugated π electrons not directly connected to an azo group , wherein the azo dye is represented by the following general formula (A).
Formula (A): A-N = N-B-N = N-C
In general formula (A),
A represents an aromatic group or a heterocyclic group substituted with a group selected from the group consisting of a sulfo group, a cyano group, and an alkyl group substituted with a sulfo group.
B represents a ring structure represented by the following general formula (2) or (3).
C represents a ring structure represented by the following general formula (1).

R ₅ represents a cyano group, an alkoxycarbonyl group, a carboxyl group or a carbamoyl group.
R ₆ and R ₇ represent an aromatic group or a heterocyclic group substituted with a group selected from the group consisting of a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an alkoxy group, and an acylamino group. .

In the general formula (1), B ₁ and B ₂ are each = CR ₁ - represents a and -CR ₂ =.
R ₁ and R ₂ each independently represents a hydrogen atom, an aliphatic group, or a cyano group.
R ₃ represents an aromatic group, and the aromatic group may be substituted with a sulfo group.
R ₄ represents a hydrogen atom.
G represents an anilino group which may be substituted with a sulfo group.
2. In the following stability test method, the residual ratio of the dye was improved by increasing the amount of the aromatic ring not directly connected to the azo group to an amount corresponding to 6 or more conjugated π electrons to the azo dye having a residual ratio of the dye of 60% or less. 2. The ink according to 1 above, comprising at least one azo dye.
Stability test method: Dissolve 0.1 mmol of dye in 10 ml of water, add 84 mg of NaHCO ₃ , heat to reflux for 1 hour, cool, and measure the residual ratio of the dye with a spectrophotometer.
3. 3. The ink according to 1 or 2 above, wherein the azo dye is a water-soluble disazo or polyazo dye.
4). The ink according to any one of 1 to 3 above, wherein the azo dye has the following physical property 1.
Physical property 1: When the maximum absorption wavelength of the absorption spectrum measured with a DMF solvent is λmax (DMF), 680 ≧ λmax (DMF) ≧ 570 nm.
5. 5. The ink according to any one of 1 to 4 above, wherein the azo dye has the following physical property 2.
Physical property 2: The oxidation potential is noble from 1.0 V (vs SCE).
6). 6. The ink according to any one of 1 to 5 above, wherein the azo dye has the following physical property 3.
Physical property 3: | λmax (DMF) −λmax (water) | ≧ 30 nm, where λmax (water) is the maximum absorption wavelength of the absorption spectrum measured with a water solvent.
7). 7. The ink according to any one of 1 to 6 above, wherein the azo dye has the following physical property 4.
Physical property 4: When the molar extinction coefficient in the DMF solvent is ε (DMF) and the molar extinction coefficient in the water solvent is ε (water), ε (water) / ε (DMF) ≦ 0.9.
8). 8. The ink according to any one of 1 to 7 above, wherein the azo dye has the following physical property 5.
Physical property 5: When λmax (water) is defined as the absorption maximum wavelength of the aggregate, and λmax (DMF) is defined as the absorption maximum wavelength of the monomer, Abs (association) ), Abs (monomer) / Abs (aggregate) ≦ 0.75, where Abs (monomer) is the absorbance at the absorption maximum wavelength of the monomer.
9. The ink according to any one of 1 to 8, wherein the azo dye contains a nitrogen-containing 6-membered ring.
10. 10. The ink according to any one of 1 to 9 above, wherein the azo dye contains a 5-membered heterocyclic ring.
11. 11. An ink for ink jet recording using the ink according to any one of 1 to 10 above .
In addition, although this invention has the structure of said 1-11, below, it described for reference also about others.

  The ink of the present invention is stable even when stored for a long period of time, and can give a colored image or coloring material excellent in hue and fastness. In particular, the ink for ink jet recording and the ink jet recording method using the above-described ink of the present invention have a good hue, and form images having high fastness against light and an active gas in the environment, particularly ozone gas. Can do.

Hereinafter, the present invention will be described in more detail.
The aromatic ring directly connected to the azo group will be described. The aromatic ring directly connected to the azo group refers to the entire aromatic ring bonded to the azo group. For example, when a naphthalene ring is directly bonded to an azo group, it refers to the entire naphthalene ring, not just one benzene ring bonded to the azo group. When the biphenyl group is bonded to the azo group, the phenyl group bonded to the azo group is a directly bonded aromatic ring, and the other phenyl group is an aromatic ring that is not directly connected. The aromatic ring includes not only an aryl group but also a heteroaromatic ring.
The azo dye used in the present invention has more than 12 aromatic conjugated π electrons not directly connected to an azo group. Calculation of the conjugated π electron is, for example, calculated as 6 + 10 = 16 for an azo dye having one benzene ring and one naphthalene ring as an aromatic ring not directly connected to an azo group. In addition, the aromatic conjugated π electron is a conjugated π electron contained in an aromatic ring (including a heterocyclic ring and not limited to a six-membered ring).

The present invention will be further described.
The following dye (f) has 12 conjugated π electrons in an aromatic ring that is not directly connected to an azo group, and the aqueous solution stability is 40% or less as measured by a stability test defined in the present invention.

In general, since the azo dye has high stability, it is unexpected that the dye (f) decomposes. This phenomenon can be theoretically explained from the value of λmax (DMF) of the dye and its oxidation potential. The dye (f) has a λmax (DMF) of 680 ≧ λmax (DMF) ≧ 570 nm related to the physical property 1 of the azo dye in the present invention, and an oxidation potential of 1.0 V (vs SCE) related to the physical property 2 of the azo dye. Meet the requirements of being more noble. 680 ≧ λmax (DMF) ≧ 570 nm is a preferable condition for a black dye, and the condition that the oxidation potential is nobler than 1.0 V (vs SCE) is a necessary condition for improving the fastness.
In order for λmax to have such a long wavelength, LUMO (lowest empty orbit) must be close to HOMO (highest occupied orbit). Also, in order for the oxidation potential to be so high, HOMO must be low. Therefore, in order to satisfy these two conditions of wavelength and potential, LUMO must be low. However, if the LUMO is low, it becomes susceptible to nucleophilic attack and the solution stability decreases. In other words, in order to develop a dye having good fastness, if a long wavelength dye is molecularly designed with a policy of increasing the oxidation potential, the solution stability is lowered.
However, the dye a-2 (described later) having a phenyl group introduced at the 4-position of the thiophene ring of this dye has a solution stability exceeding 80%. Moreover, as a result of introducing a naphthyl group, the solution stability of the dye a-3 exceeds 90%. Moreover, as a result of introducing the 4-methylphenyl group, the solution stability of the dye a-1 exceeds 90%. It is clear from these data that the solution stability is improved by introducing a phenyl group, a naphthyl group, and a 4-methylphenyl group.
Regarding this cause, an increase in the number of conjugated π electrons of the aromatic ring not directly connected to the azo group by 6 or more resulted in an association effect, a hydrophobic effect, a steric effect, and a methyl group introduced at the 4-position of the phenyl group. It is presumed that the solution stability is increased due to the association effect, hydrophobic effect and the like.

The dye a-1, the dye a-2, and the dye a-3 have a structure in which “the total number of aromatic conjugated π electrons not directly connected to the azo group exceeds 12” as specified in the present invention. Have In addition, these dyes are specified in the present invention as “the amount corresponding to 6 or more conjugated π electrons of an aromatic ring not directly bonded to an azo group in a dye having a dye residual ratio of 60% or less by the stability test method”. It has a common property and structure in that it is a “dye having improved solution stability by increasing”.
The stability test method is as follows.
[Stability test method]
Dissolve 0.1 mmol of the dye in 10 ml of water, add 84 mg of NaHCO ₃ and heat to reflux for 1 hour. After cooling, measure the residual ratio of the dye with a spectrophotometer.
In the present invention, the solution stability of the dye having improved solution stability is more preferably 80% or more, and most preferably 90% or more.
The present invention is very useful industrially in the sense that a long wavelength dye having high solution stability and good fastness can be provided.

  Regarding the physical property 1 of the azo dye, 680 ≧ λmax (DMF) ≧ 590 nm is more preferable, and 680 ≧ λmax (DMF) ≧ 610 nm is still more preferable. When the dye does not dissolve in 100% DMF, first, the dye is dissolved using water (an amount of 10% by mass or less of the DMF solvent), and this is diluted with DMF, and λmax is measured.

Next, the following physical properties 3 to 5 relating to the azo dye of the present invention, that is,
Physical property 3: | λmax (DMF) −λmax (water) |
Physical property 4: ε (water) / ε (DMF)
Physical property 5: Abs (monomer) / Abs (association)
Will be described.
When the inventors researched a dye having good fastness, the dye having good fastness was
Physical property 3: | λmax (DMF) −λmax (water) | ≧ 30 nm
Physical property 4: ε (water) / ε (DMF) ≦ 0.9
Physical property 5: Abs (monomer) / Abs (association) ≦ 0.75
It was found that at least one of the three physical properties is satisfied. It is presumed that a dye satisfying these physical properties is in an associated state in an aqueous solvent.
In general, when the λmax of the dye differs depending on the solvent, there are two possible causes. One is the case where the association state of the dye differs depending on the solvent, and the other is the case based on solvatochromism. In the present invention, the former case is presumed.
When the dye is associated, ε may decrease. [epsilon] (water) / [epsilon] (DMF) is a value obtained by dividing [epsilon] in an aqueous solvent that easily takes an associated state by [epsilon] in a DMF solvent that hardly takes an associated state. This value can be used as a measure of the meeting.
Information on the association of the dye can also be obtained from the absorption spectrum. Information on dye association can also be obtained from the absorption spectrum in an aqueous solvent. When λmax (water) is defined as the absorption maximum wavelength of the aggregate and λmax (DMF) is defined as the absorption maximum wavelength of the monomer, Abs (association) represents the absorbance at the absorption maximum wavelength of the aggregate in the absorption spectrum in the aqueous solvent. Abs (monomer) is the ratio of apparent non-associating molecules, where Abs (monomer) is the absorbance at the absorption maximum wavelength of each (measured at 2 × 10 ⁻⁵ mol / L). become. That is, it can be said that the smaller this value is, the more molecules are associated. If a dye having a high oxidation potential adopts the association state described here, the dye becomes more robust.

Specifically, a disazo or polyazo dye represented by the following general formula (A) is preferable. In the formula, A, B and C each independently represent an optionally substituted aromatic group or an optionally substituted heterocyclic group (A and C are monovalent groups, and B represents two Valent group). When the substituent is an aromatic azo group, the dye of the general formula (A) represents a polyazo dye.
Formula (A): A-N = N-B-N = N-C

Next, the nitrogen-containing 6-membered ring in the present invention will be described.
The nitrogen-containing 6-membered ring refers to a ring containing a nitrogen atom as a ring constituent atom such as a pyridine ring, and is preferably a ring represented by the general formula (1). It is more preferable that the part of is this ring.

In the general formula (1), B ₁ and B ₂ each represent = CR ₁ -and -CR ₂ =, or either one represents a nitrogen atom and the other represents = CR ₁ -or -CR ₂ =. .
G, R ₁ and R ₂ are each independently a hydrogen atom, halogen atom, aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, Heterocyclic oxycarbonyl group, acyl group, hydroxy group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (anilino group) A heterocyclic amino group), acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkyl or arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkyl and Arylchi Represents an o group, a heterocyclic thio group, an alkyl and arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl and arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group, or a sulfo group, and each group may be further substituted.
R ₃ and R ₄ each independently represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl or arylsulfonyl group, or a sulfamoyl group. Each group may further have a substituent. However, R ₃ and R ₄ are not simultaneously hydrogen atoms.
R ₁ and R ₅ , or R ₃ and R ₄ may be bonded to form a 5- to 6-membered ring.

Next, the 5-membered heterocyclic ring in the present invention will be described.
The 5-membered heterocyclic ring refers to a 5-membered ring containing a hetero atom, and is preferably an aromatic ring. Preferred heteroatoms are sulfur, nitrogen, and oxygen, and examples of the 5-membered heterocyclic ring include a thiophene ring, a thiazole ring, and an imidazole ring. Further, it may be further condensed such as a benzothiazole ring and a thienothiazole ring. Each heterocyclic group may further have a substituent. Among these, thiophene rings, thiazole rings, imidazole rings, benzothiazole rings, and thienothiazole rings represented by the following general formulas (2) to (6) are preferable. A thiophene ring and a thiazole ring are more preferable, and it is more preferable that the portion B in the general formula (A) is this ring.

In the general formulas (2) to (6), R ₅ to R ₁₃ represent a substituent having the same meaning as G, R ₁ , and R ₂ in the general formula (1).
In the present invention, particularly preferred azo dye structures are those represented by the following general formulas (7) and (8).

In the general formulas (7) and (8), Z ₁ represents an electron-withdrawing group having a Hammett's substituent constant σp value of 0.20 or more. Z ₁ is preferably an electron-withdrawing group having a σp value of 0.30 or more, more preferably an electron-withdrawing group of 0.45 or more, and particularly preferably an electron-withdrawing group of 0.60 or more. It is desirable not to exceed 0.0.
A preferred specific substituent will be described. As an electron-withdrawing group having a Hammett substituent constant σp value of 0.60 or more, a cyano group, a nitro group, an alkylsulfonyl group (for example, a methanesulfonyl group, an arylsulfonyl group (for example, benzene) A sulfonyl group) can be mentioned as an example.
Examples of the electron-withdrawing group having a Hammett σp value of 0.45 or more include an acyl group (for example, acetyl group), an alkoxycarbonyl group (for example, dodecyloxycarbonyl group), an aryloxycarbonyl group (for example, m-chlorophenoxycarbonyl) in addition to the above. ), An alkylsulfinyl group (for example, n-propylsulfinyl), an arylsulfinyl group (for example, phenylsulfinyl), a sulfamoyl group (for example, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), a halogenated alkyl group ( For example, trifluoromethyl) can be mentioned.
As the electron-withdrawing group having a Hammett substituent constant σp value of 0.30 or more, in addition to the above, an acyloxy group (for example, acetoxy), a carbamoyl group (for example, N-ethylcarbamoyl, N, N-dibutylcarbamoyl), halogen Alkoxy group (for example, trifluoromethyloxy), halogenated aryloxy group (for example, pentafluorophenyloxy), sulfonyloxy group (for example, methylsulfonyloxy group), halogenated alkylthio group (for example, difluoromethylthio), 2 An aryl group (eg, 2,4-dinitrophenyl, pentachlorophenyl) substituted with one or more electron-withdrawing groups having a σp value of 0.15 or more, and a heterocycle (eg, 2-benzoxazolyl, 2- Benzothiazolyl, 1-phenyl-2-benzimidazolyl) be able to.
Specific examples of the electron-withdrawing group having a σp value of 0.20 or more include a halogen atom in addition to the above. Among them, an acyl group having 2 to 20 carbon atoms, an alkyloxycarbonyl group having 2 to 20 carbon atoms, a nitro group, a cyano group, an alkylsulfonyl group having 1 to 20 carbon atoms, an arylsulfonyl group having 6 to 20 carbon atoms, carbon A carbamoyl group having 1 to 20 carbon atoms and a halogenated alkyl group having 1 to 20 carbon atoms are preferable. Particularly preferred are a cyano group, an alkylsulfonyl group having 1 to 20 carbon atoms, and an arylsulfonyl group having 6 to 20 carbon atoms, and most preferred is a cyano group.

R ₁ , R ₂ , R ₃ , and R ₄ have the same meaning as in general formula (1). R ₁₄ and R ₁₅ are each independently a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkyl and arylsulfonyl group, or sulfamoyl group. Represents. Among these, a hydrogen atom, an aromatic group, a heterocyclic group, an acyl group, an alkyl or arylsulfonyl group is preferable, and a hydrogen atom, an aromatic group, and a heterocyclic group are particularly preferable.
R ₁₆ represents an alkyl group, an aromatic group, or a heterocyclic group, and an aromatic group is particularly preferable among them.

  A is synonymous with the general formula (A) and represents an optionally substituted aromatic group or heterocyclic group. Preferably, it represents an aromatic group.

Each group described in the general formulas (7) and (8) may further have a substituent. When each of these groups further has a substituent, examples of the substituent include the substituents described in the general formula (1), the groups exemplified for G, R ₁ and R ₂ , and water-soluble groups.

The azo dye of the present invention is preferably a water-soluble dye. The water-soluble dye refers to a dye to which a water-soluble group is bonded. Preferred water-soluble groups of the dye of the present invention include a sulfo group, a carboxyl group, a thiocarboxyl group, a sulfino group, a phosphono group, and a dihydroxyphosphino group. Etc. Particularly preferred are a sulfo group and a carboxyl group. The number of water-soluble groups is preferably 3 or more, and more preferably 4 or more. The water-soluble group may be substituted at any position, but it is preferably contained in A or C of the general formula (A).
The carboxyl group, phosphono group, and sulfo group may be in the form of a salt. Examples of counter ions that form a salt include ammonium ions, alkali metal ions (eg, lithium ions, sodium ions, potassium ions), and organic ions. Cations (eg, tetramethylammonium ion, tetramethylguanidinium ion, tetramethylphosphonium) are included, lithium salts and ammonium salts are preferable, and lithium salts are more preferable.
The “aromatic conjugated π electron not directly bonded to an azo group” of the present invention is preferably contained in B or C of the general formula (A).

Next, the oxidation potential will be described. The oxidation potential is preferably nobler than 1.0 V (vs SCE). The oxidation potential is preferably as noble, and the oxidation potential is preferably noble from 1.2 V (vs SCE). The reason why the ozone fastness of the colored image is improved is estimated as follows. The decomposition of the dye by ozone gas is the relationship between the HOMO (maximum occupied orbit) and LUMO (lowest orbit) of the dye and ozone gas, that is, the color compound is oxidized and decomposed by the reaction of HOMO of the azo compound and LUMO of the ozone gas, It is considered that the density of the colored image is lowered. Therefore, it is presumed that by setting the azo compound to a specific oxidation potential, the HOMO of the compound is lowered, the reactivity with the ozone gas is lowered, and the fastness of the ozone gas is improved.
The value of the oxidation potential represents the ease of electron transfer from the sample to the electrode. The higher the value (the higher the oxidation potential), the more difficult the electron transfer from the sample to the electrode, in other words, the less the oxidation potential. Represents. In relation to the structure of the compound, the oxidation potential becomes more noble by introducing an electron withdrawing group, and the oxidation potential becomes lower by introducing an electron donating group.

  The value of the oxidation potential, which will be described in detail below, means the potential at which the compound is an anode in voltammetry and the electron of the compound is extracted, and is considered to approximately match the energy level of HOMO in the ground state of the compound. Yes.

The measurement of the oxidation potential will be specifically described. The oxidation potential is 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ mol · dm ^{−3 in} a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. Dissolve and measure as a value for SCE (saturated calomel electrode) using cyclic voltammetry or direct current polarography.
The supporting electrolyte and solvent to be used can be selected appropriately depending on the oxidation potential and solubility of the test sample. For example, P. Delahay "New Instrumental Methods in Electrochemistry (1954 Interscience Publishers)
And AJ Bard et al., "Electrochemical Methods" (1980 John Wiley & Sons), Fujishima Akira et al., Electrochemical Measurement Methods (1984, published by Gihodo Publishing Co., Ltd.), pages 101-118.

  The value of the oxidation potential may be deviated by several tens of mil volts due to the influence of the inter-liquid potential difference or the liquid resistance of the sample solution, but the potential measured by calibrating with a standard sample (for example, hydroquinone). The reproducibility of the value of can be guaranteed.

The oxidation potential in the present invention is a mixture of water / N, N-dimethylformamide = 2/98 containing 0.1 mol · dm ⁻³ of tetrapropylammonium perchlorate as a supporting electrolyte (the concentration of the compound is 1 × 10 ⁻³ mol · dm ⁻³ ), SCE (saturated calomel electrode) as a reference electrode, a graphite electrode as a working electrode, and a platinum electrode as a counter electrode, and values measured by direct current polarography are used.

  Further, in the present invention, as a method for making the oxidation potential noble, a method for selecting a compound having a noble structure, a method for introducing an electron withdrawing group at an arbitrary position, that is, an electron withdrawing of a substituent. And a method of introducing a substituent having a large Hammett's substituent constant σp, which is a measure of the property and electron donating property. The method of selecting a dye structure having an oxidation potential that is originally noble is not limited to ozone gas fastness, but any other electron-withdrawing group or electron-donating group may be used to adjust other fastness, hue, physical properties, etc. It is preferable from the viewpoint of molecular design.

  In addition, in order to lower the reactivity with ozone, which is an electrophile, a method in which an electron withdrawing group is introduced at an arbitrary position in the structure of the compound to make the oxidation potential more noble, By using Hammett's substituent constant σp value, which is a measure of attractiveness and electron donating property, the oxidation potential can be made more noble by introducing a substituent having a large σp value.

  Hammett's substituent constant σp value will be described. Hammett's rule is an empirical rule proposed by L. P. Hammett in 1935 to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives, but this is widely accepted today. Substituent constants obtained by Hammett's rule include σp value and σm value, and these values can be found in many general books. For example, JA Dean edition “Lange's Handbook of Chemistry” For more information, please refer to the edition (1979 McGraw-Hill) and “Chemicals” special edition, 122, 96-103 (1979 Nankodo). In the present invention, each substituent is limited or explained by Hammett's substituent constant σp, which means that it can be found in the above-mentioned book and is limited only to a substituent having a known value in the literature. However, it goes without saying that even if the value is unknown, it also includes a substituent that would be included in the range when measured based on Hammett's rule. In addition, the general formula (1) or (2) of the present invention includes those that are not benzene derivatives, but the σp value is used as a scale indicating the electronic effect of the substituent regardless of the substitution position. In the present invention, the σp value is used in this sense.

Specific examples of the azo compound contained in the colored composition of the present invention are shown below, but the azo compound used in the present invention is not limited to the following examples, and also includes a carboxyl group, a phosphono group, and a sulfo group. May be in the form of a salt, and examples of counter ions that form salts include ammonium ions, alkali metal ions (eg, lithium ions, sodium ions, potassium ions) and organic cations (eg, tetramethylammonium ions, Tetramethylguanidinium ion, tetramethylphosphonium ion).
The dye of the present invention can be synthesized by a coupling reaction between a diazo component and a coupler. A synthesis example is shown below.

[Synthesis Example of Dye b-2]
(Synthesis of diazo component B-2)
22.7 g (65.4 mmol) of 7-aminonaphthalene-1,5-disulfonic acid (hereinafter referred to as C acid) disodium was added to 190 ml of water, 25 ml of concentrated hydrochloric acid was added, and the mixture was cooled to 0 ° C. Then, a solution obtained by dissolving 4.74 g (68.7 mmol) of sodium nitrite in 20 ml of water was added at 0 to 5 ° C. and stirred at 0 to 5 ° C. for 1 hour to obtain a diazo solution of C acid. Separately, 10.0 g (59.5 mmol) of 2-amino-4-phenyl-thiazole was dispersed in 150 ml of water. The C acid diazo solution was added to this dispersion at room temperature. After the addition, sodium acetate was added until pH = 2. The disappearance of thiophene is confirmed by liquid chromatography, and sodium acetate is further added to obtain pH = 7. The slurry was filtered and washed with isopropyl alcohol. The wet cake taken out was dissolved in 400 ml of water, and 31 g of lithium chloride was added for salting out. The slurry was filtered and washed with isopropyl alcohol.
The obtained wet cake was dried to obtain 26.3 g (crude yield 88%) of diazo component B-2.
(Synthesis of Dye b-2)
To 300 ml of phosphoric acid and 150 ml of acetic acid, 7.0 g of 40% nitrosylsulfuric acid was added and cooled to -2 ° C. Then, a solution obtained by dissolving 10 g (19.9 mmol) of diazo component B-2 in 30 ml of water was dropped at −2 ° C. to 0 ° C. and stirred at −2 ° C. to 0 ° C. for 1 hour. The diazo liquid was used. Separately, 9.8 g (19.9 mmol) of coupler P was dissolved in 450 ml of water and cooled to 5 ° C. The B-2 diazo solution was added dropwise to this solution at 5 to 10 ° C. and stirred at 5 to 10 ° C. for 1 hour. The reaction solution was heated to 40 ° C., and 52 g of lithium chloride was added for salting out. The slurry was filtered and washed with isopropyl alcohol. The obtained wet cake was dissolved in 300 ml of water, and 100 ml of concentrated hydrochloric acid was added. This was heated to 40 ° C., and 49 g of lithium chloride was added for salting out. The slurry was filtered and washed with isopropyl alcohol. The obtained wet cake was dissolved in 30 ml of water and 60 ml of methanol, neutralized to pH = 7 with an aqueous lithium hydroxide solution, heated to 65 ° C., and 270 ml of isopropyl alcohol was added dropwise for crystallization. The slurry was filtered and washed with isopropyl alcohol. A 1/4 amount of the obtained wet cake was dissolved in 30 ml of water and purified with a Sephadex LH-20 column manufactured by Amersham Biosciences to obtain 2.3 g of the target product (dye b-2) (
Yield 47%) was obtained. (M / S: (M−H) ⁻ = 961, (M−2H) ²⁻ = 480, λmax (water) = 588 nm)
The synthesis route is shown below.

[Synthesis Example of Dye b-3]
(Synthesis of diazo component B-3)
16.9 g (48.6 mmol) of 7-aminonaphthalene-1,5-disulfonic acid (hereinafter referred to as C acid) disodium was added to 140 ml of water, 19 ml of concentrated hydrochloric acid was added, and the mixture was cooled to 0 ° C. Then, a solution prepared by dissolving 3.35 g (48.6 mmol) of sodium nitrite in 12 ml of water was added at 0 to 5 ° C. and stirred at 0 to 5 ° C. for 1 hour to obtain a diazo solution of C acid. Separately, 10.0 g (44.2 mmol) of 2-amino-4-naphthyl-thiazole was dispersed in 500 ml of water. The C acid diazo solution was added to this dispersion at room temperature. After the addition, the mixture was stirred for 30 minutes, sodium acetate was added to adjust the pH to 4, and the mixture was heated to 40 ° C. and stirred for 2 hours. The disappearance of thiazole was confirmed by liquid chromatography, and sodium acetate was further added to obtain pH = 7. The slurry was filtered and washed with isopropyl alcohol. The wet cake taken out was dissolved in 400 ml of water, and 29 g of lithium chloride was added to cause salting out. The slurry was filtered and washed with isopropyl alcohol.
The obtained wet cake was dried to obtain 19.3 g (crude yield 79%) of diazo component B-3.
(Synthesis of Dye b-3)
To 300 ml of phosphoric acid and 150 ml of acetic acid, 6.3 g of 40% nitrosylsulfuric acid was added and cooled to -2 ° C. Then, a solution obtained by dissolving 10 g (18.1 mmol) of diazo component B-3 in 30 ml of water was dropped at −2 ° C. to 0 ° C. and stirred at −2 ° C. to 0 ° C. for 1 hour. The diazo liquid was used. Separately, 9.0 g (18.1 mmol) of coupler P was dissolved in 450 ml of water and cooled to 5 ° C. The B-3 diazo solution was added dropwise to this solution at 5 to 10 ° C. and stirred at 5 to 10 ° C. for 1 hour. The reaction solution was heated to 40 ° C., and 38 g of lithium chloride was added to cause salting out. The slurry was filtered and washed with isopropyl alcohol. The obtained wet cake was dissolved in 300 ml of water, and 100 ml of concentrated hydrochloric acid was added. This was heated to 40 ° C., and 43 g of lithium chloride was added for salting out. The slurry was filtered and washed with isopropyl alcohol. The obtained wet cake was dissolved in 30 ml of water and 60 ml of methanol, neutralized with an aqueous lithium hydroxide solution to pH = 7, heated to 65 ° C., and 270 ml of isopropyl alcohol was added dropwise for crystallization. The slurry was filtered and washed with isopropyl alcohol. A quarter amount of the obtained wet cake was dissolved in 30 ml of water and purified with a Sephadex LH-20 column manufactured by Amersham Biosciences to obtain 2.1 g of the desired product (dye b-3) (
Yield 45%). (M / S: (M−H) ⁻ = 1011, (M−2H) ²⁻ = 505, λmax (water) = 600 nm)
The synthesis route is shown below.

  The physical properties of the dyes obtained by the above synthesis method are as follows. As a comparative example, the physical property values of the dye (f) are described.

Next, ink jet ink will be described.
The ink for inkjet recording can be prepared by dissolving or dispersing the azo dye in an oleophilic medium or an aqueous medium. Preferably, an aqueous medium is used. If necessary, other additives are contained within a range that does not impair the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, Well-known additives, such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, a chelating agent, are mentioned.
These various additives are directly added to the ink liquid in the case of water-soluble ink. When the oil-soluble dye is used in the form of a dispersion, it is generally added to the dispersion after the preparation of the dye dispersion, but it may be added to the oil phase or the aqueous phase at the time of preparation.

The anti-drying agent is preferably used for the purpose of preventing clogging due to drying of the ink-jet ink at the ink jet port of the nozzle used in the ink-jet recording method.
As the drying inhibitor, a water-soluble organic solvent having a vapor pressure lower than that of water is preferable. Specific examples include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycol derivatives, Polyhydric alcohols typified by glycerin, trimethylolpropane, etc., lower alkyl of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether Ethers, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, heterocyclic rings such as N-ethylmorpholine, sulfolane, dimethyl sulfoxide, - sulfur-containing compounds such as sulfolane, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Of these, polyhydric alcohols such as glycerin and diethylene glycol are more preferred. Moreover, said drying inhibitor may be used independently and may be used together 2 or more types. These drying inhibitors are preferably contained in the ink in an amount of 10 to 50% by mass.

  The penetration enhancer is preferably used for the purpose of allowing the ink for inkjet to penetrate better into paper. As the penetration enhancer, alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, nonionic surfactants, etc. may be used. it can. If these are contained in the ink in an amount of 5 to 30% by mass, they usually have a sufficient effect, and it is preferable to use them in a range of addition amounts that do not cause printing bleeding and paper loss (print through).

  The ultraviolet absorber is used for the purpose of improving image storability. Examples of the ultraviolet absorber include benzotriazoles described in JP-A Nos. 58-185677, 61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194433, U.S. Pat. No. 3,214,463, etc., JP-B Nos. 48-30492, 56-21114, Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP-A-8 No. -502911, etc., triazine compounds, Research Disclosure No. Compounds described in No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene-based and benzoxazole-based compounds, so-called fluorescent brighteners, can also be used.

  The anti-fading agent is used for the purpose of improving image storage stability. As the antifading agent, various organic and metal complex antifading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like. More specifically, Research Disclosure No. No. 17643, Nos. VII to I, J; 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of the representative compounds described in pages 127 to 137 of JP-A-62-215272 can be used.

  Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one, and salts thereof. These are preferably used in the ink in an amount of 0.02 to 1.00% by mass.

  As the pH adjuster, a neutralizer (organic base, inorganic alkali) can be used. For the purpose of improving the storage stability of the inkjet ink, the pH adjuster is preferably added to the inkjet ink for the summer of pH 6 to 10, and more preferably added to a pH of 7 to 10.

Examples of the surface tension adjusting agent include nonionic, cationic and anionic surfactants. The surface tension of the inkjet ink of the present invention is preferably 20 to 60 mN / m, and more preferably 25 to 45 mN / m. Further, the viscosity of the ink for inkjet recording of the present invention is preferably 30 mN / m or less. Furthermore, it is more preferable to adjust to 20 mN / m or less.
Examples of surfactants include fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl sulfates. Anionic surfactants such as ester salts, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester Nonionic surfactants such as oxyethyleneoxypropylene block copolymers are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred. Further, pages (37) to (38) of JP-A-59-157,636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used.

  As the antifoaming agent, fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can be used as necessary.

  As the aqueous medium, a mixture containing water as a main component and optionally adding a water-miscible organic solvent can be used. Examples of water miscible organic solvents include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol), polyhydric alcohols (E.g., ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), glycol derivatives (e.g., Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether Diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether , Triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amine (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, Reethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2- Pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone). In addition, the said water miscible organic solvent may use 2 or more types together.

  In 100 parts by mass of the inkjet recording ink of the present invention, the azo dye is preferably contained in an amount of 0.2 to 30 parts by mass. In the ink for inkjet recording of the present invention, other colorant may be used in combination with the azo dye. When two or more colorants are used in combination, the total content of the colorants is preferably within the above range.

The ink for inkjet recording of the present invention can be used not only for forming a single color image but also for forming a full color image. In order to form a full-color image, magenta color ink, cyan color ink, and yellow color ink can be used.
Any yellow dye can be used. For example, aryl or heteryl azo dyes having phenols, naphthols, anilines, heterocycles such as pyrazolone and pyridone, open-chain active methylene compounds, etc. as coupling components (hereinafter referred to as coupler components); Azomethine dyes having open chain active methylene compounds, etc .; methine dyes such as benzylidene dyes and monomethine oxonol dyes; quinone dyes such as naphthoquinone dyes and anthraquinone dyes, and other dye species Examples thereof include quinophthalone dyes, nitro / nitroso dyes, acridine dyes, and acridinone dyes.
Any applicable magenta dye can be used. For example, aryl or heteryl azo dyes having phenols, naphthols, anilines, heterocycles such as pyrazine, open-chain active methylene compounds, etc. as coupling components (hereinafter referred to as coupler components); Examples include azomethine dyes having methylene compounds and the like; anthrapyridone dyes.

  Any applicable cyan dye can be used. For example, aryl or heteryl azo dyes having phenols, naphthols, anilines and the like as coupler components; for example, azomethine dyes having phenols, naphthols, heterocyclic rings such as pyrrolotriazole as coupler components; cyanine dyes, oxonol dyes, Polymethine dyes such as merocyanine dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes; phthalocyanine dyes; anthraquinone dyes; indigo / thioindigo dyes.

  Each of these dyes may exhibit yellow and cyan colors only after part of the chromophore is dissociated, and the counter cation in that case may be an alkali metal or an inorganic cation such as ammonium. Alternatively, it may be an organic cation such as pyridinium or quaternary ammonium salt, and may further be a polymer cation having them in a partial structure.

[Inkjet recording method]
In the ink jet recording method of the present invention, energy is supplied to the ink for ink jet recording, and a known image receiving material, that is, plain paper, resin-coated paper, such as JP-A-8-169172, JP-A-8-27693, JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783, JP-A-10-153989, JP-A-10-217473, JP-A-10-235995 10-337947, 10-217597, 10-337947, etc. Form images on inkjet paper, film, electrophotographic co-paper, fabric, glass, metal, ceramics, etc. To do.

  In forming an image, a polymer latex compound may be used in combination for the purpose of imparting glossiness or water resistance or improving weather resistance. The timing of applying the latex compound to the image receiving material may be before, after, or simultaneously with the application of the colorant. Therefore, even if the addition place is in the image receiving paper, It may be in ink or may be used as a liquid material of polymer latex alone. Specifically, JP 2002-166638, JP 2002-121440, JP 2002-154201, JP 2002-144696, JP 2002-080759, JP 2002-187342, JP 2002-172774. The method described in each publication of No. can be preferably used.

Hereinafter, a recording paper and a recording film used for ink jet printing using the ink of the present invention will be described.
The support in recording paper and recording film is made of chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMPMP, CGP, and waste paper pulp such as DIP. Additives such as known pigments, binders, sizing agents, fixing agents, cationic agents, paper strength enhancers, etc. can be mixed and used in various devices such as long net paper machines and circular net paper machines. is there. In addition to these supports, either synthetic paper or plastic film sheet may be used, and the thickness of the support is preferably 10 to 250 μm and the basis weight is preferably 10 to 250 g / m ² . The support may be provided with an ink receiving layer and a backcoat layer as they are, or after a size press or an anchor coat layer is provided with starch, polyvinyl alcohol or the like, an ink receiving layer and a backcoat layer may be provided. Further, the support may be flattened by a calendar device such as a machine calendar, a TG calendar, or a soft calendar. In the present invention, as the support, paper and plastic films laminated on both sides with polyolefin (for example, polyethylene, polystyrene, polyethylene terephthalate, polybutene and copolymers thereof) are more preferably used. It is preferable to add a white pigment (for example, titanium oxide or zinc oxide) or a coloring dye (for example, cobalt blue, ultramarine blue, or neodymium oxide) to the polyolefin.

  The ink receiving layer provided on the support contains a pigment and an aqueous binder. As the pigment, a white pigment is preferable, and as the white pigment, calcium carbonate, kaolin, talc, clay, diatomaceous earth, synthetic amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, alumina, lithopone, zeolite, Examples thereof include white inorganic pigments such as barium sulfate, calcium sulfate, titanium dioxide, zinc sulfide and zinc carbonate, and organic pigments such as styrene pigments, acrylic pigments, urea resins and melamine resins. As the white pigment contained in the ink receiving layer, porous inorganic pigments are preferable, and synthetic amorphous silica having a large pore area is particularly preferable. As the synthetic amorphous silica, either anhydrous silicic acid obtained by a dry production method or hydrous silicic acid obtained by a wet production method can be used, but it is particularly desirable to use hydrous silicic acid.

Examples of the aqueous binder contained in the ink receiving layer include water-soluble polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyalkylene oxide, polyalkylene oxide derivatives, and the like. Water-dispersible polymers such as water-soluble polymers, styrene butadiene latexes, and acrylic emulsions. These aqueous binders can be used alone or in combination of two or more. In the present invention, among these, polyvinyl alcohol and silanol-modified polyvinyl alcohol are particularly preferable in terms of adhesion to the pigment and resistance to peeling of the ink receiving layer.
The ink receiving layer can contain a mordant, a water resistance agent, a light resistance improver, a surfactant, and other additives in addition to the pigment and the aqueous binder.

The mordant added to the ink receiving layer is preferably immobilized. For that purpose, a polymer mordant is preferably used.
For the polymer mordant, JP-A-48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, 60-23835, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122942, 60- No. 235134, JP-A-1-161236, U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,273,853, 4,282,305, It is described in each specification of the same No. 4450224. An image receiving material containing a polymer mordant described in JP-A-1-161236, pages 212 to 215 is particularly preferred. When the polymer mordant described in the publication is used, an image with excellent image quality is obtained and the light resistance of the image is improved.

  The water-proofing agent is effective for making the image water-resistant. As these water-proofing agents, cationic resins are particularly desirable. Examples of such cationic resins include polyamide polyamine epichlorohydrin, polyethyleneimine, polyamine sulfone, dimethyl diallyl ammonium chloride polymer, cationic polyacrylamide, colloidal silica, etc. Among these cationic resins, polyamide polyamine epichlorohydrin is particularly preferable. is there. The content of these cationic resins is preferably 1 to 15% by mass, particularly 3 to 10% by mass, based on the total solid content of the ink receiving layer.

  Examples of the light resistance improver include zinc sulfate, zinc oxide, hindered amine antioxidants, and benzotriazole ultraviolet absorbers such as benzophenone. Of these, zinc sulfate is particularly preferred.

  The surfactant functions as a coating aid, a peelability improver, a slippage improver or an antistatic agent. The surfactant is described in JP-A Nos. 62-173463 and 62-183457. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compound include a fluorine-based surfactant, an oily fluorine-based compound (for example, fluorine oil), and a solid fluorine compound resin (for example, tetrafluoroethylene resin). The organic fluoro compounds are described in JP-B-57-9053 (columns 8 to 17), JP-A-61-20994, and 62-135826. Examples of other additives added to the ink receiving layer include pigment dispersants, thickeners, antifoaming agents, dyes, fluorescent whitening agents, preservatives, pH adjusters, matting agents, and hardening agents. . The ink receiving layer may be one layer or two layers.

  The recording paper and the recording film can be provided with a back coat layer, and examples of components that can be added to this layer include a white pigment, an aqueous binder, and other components. Examples of white pigments contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and aluminum silicate. White inorganic pigments such as diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide And organic pigments such as styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin and melamine resin.

  As the aqueous binder contained in the backcoat layer, styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose Water-soluble polymers such as hydroxyethyl cellulose and polyvinyl pyrrolidone, water-dispersible polymers such as styrene butadiene latex and acrylic emulsion, and the like. Examples of other components contained in the back coat layer include antifoaming agents, foam suppressors, dyes, fluorescent brighteners, preservatives, and water resistance agents.

  Polymer latex may be added to the constituent layers (including the backcoat layer) of the ink jet recording paper and recording film. The polymer latex is used for the purpose of improving film physical properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer latex is described in JP-A Nos. 62-245258, 62-1316648, and 62-110066. When a polymer latex having a low glass transition temperature (40 ° C. or lower) is added to a layer containing a mordant, cracking and curling of the layer can be prevented. Also, curling can be prevented by adding a polymer latex having a high glass transition temperature to the backcoat layer.

  The ink of the present invention is not limited to an ink jet recording system, and is a known system, for example, a charge control system that discharges ink using electrostatic attraction, a drop-on-demand system (pressure) that uses the vibration pressure of a piezo element. Pulse method), acoustic ink jet method that converts electrical signal into acoustic beam and irradiates ink and uses ink to discharge ink, and thermal ink jet that heats ink to form bubbles and uses generated pressure Used for systems. Inkjet recording methods use a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method is included.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples at all.
[Example 1]
After adding deionized water to the following components to make 1 liter, the mixture was stirred for 1 hour while being heated at 30 to 40 ° C. Thereafter, the pH was adjusted to 9 with LiOH 10 mol / L, and the mixture was filtered under reduced pressure with a microfilter having an average pore size of 0.25 μm to prepare a dye ink liquid A.

Composition of ink liquid A:
25 g of the dye (b-2) of the present invention
Diethylene glycol 20g
Glycerin 120g
230 g of diethylene glycol monobutyl ether
2-Pyrrolidone 80g
Triethanolamine 17.9g
Benzotriazole 0.06g
Surfynol TG 8.5g
PROXEL XL2 1.8g

  Ink liquids B and C were prepared in the same manner as ink liquid A, except that the dyes were changed as shown in Table 2 below. Moreover, the ink liquid 1 was created using the comparative dye of Table 2 as a comparative ink liquid.

  When changing the dye, it was used so that the added amount of the dye was equimolar with respect to the ink liquid A. When two or more dyes were used in combination, equimolar amounts were used.

(Image recording and evaluation)
The following evaluation was performed on the ink jet ink composed of the above ink liquids A to E and the comparative ink liquid 1. The results are shown in Table 2.
In Table 2, “paper dependency”, “water resistance”, “light resistance”, “dark heat storage stability”, and “ozone gas resistance” indicate that each inkjet ink is an inkjet printer (EPSON Co., Ltd.). PM-700C) was recorded on photo glossy paper (manufactured by EPSON PM photographic paper <Glossy> (KA420PSK, EPSON)) and then evaluated by the following method.

<Ink stability>
Dissolve 0.1 mmol of the dye in 10 ml of water, add 84 mg of NaHCO ₃ , heat to reflux for 1 hour, cool, measure the residual ratio of the dye by absorbance, and if the residual ratio is 80% or more, A, 60% or more The case of less than 80% was designated as B, and the case of less than 60% was designated as C.
<Paper dependence>
The color tone of the image formed on the photo glossy paper and the image formed separately on the PPC plain paper are compared, and when the difference between the two images is small A (good), when the difference between the two images is large B (defect) was evaluated in two stages.

<Water resistance>
The photo glossy paper on which the image was formed was dried at room temperature for 1 hour, then immersed in deionized water for 10 seconds, and naturally dried at room temperature, and bleeding was observed. Evaluation was made in three stages, with A indicating no bleeding, B indicating slight bleeding, and C indicating large bleeding.

<Light resistance>
The photo glossy paper on which the image is formed is irradiated with xenon light (85000 lx) for 7 days using a weather meter (Atlas C.I65), and the image density before and after the xenon irradiation is measured using a reflection densitometer (X-Rite310TR). And measured as a dye residual ratio. The reflection density was measured at three points of 1, 1.5 and 2.0.
Evaluation was made in three stages, with A being a dye residual ratio of 70% or more at any concentration, A being 1 or 2 points being less than 70% B, and C being less than 70% at all concentrations.

<Dark heat preservation>
The photo glossy paper on which the image was formed was stored for 7 days under conditions of 80 ° C. and 15% RH, and the image density before and after storage was measured using a reflection densitometer (X-Rite310TR), and the residual dye rate As evaluated. The dye residual rate is evaluated at three points of reflection density of 1, 1.5, 2 and A is the case where the dye residual rate is 90% or more at any concentration, and B is the case where 1 or 2 points are less than 90%. , C was defined as less than 90% at all concentrations.

<Ozone gas resistance>
The photo glossy paper on which the image has been formed is left in a box set at an ozone gas concentration of 0.5 ± 0.1 ppm, room temperature and dark place for 7 days, and the image density before and after being left under ozone gas is measured by a reflection densitometer (X -Rite310TR) and evaluated as the residual ratio of the dye. The reflection density was measured at three points of 1, 1.5 and 2.0. The ozone gas concentration in the box was set using an ozone gas monitor (model: OZG-EM-01) manufactured by APPLICS.
Evaluation was made in three stages, with A being a dye residual ratio of 70% or more at any concentration, A being 1 or 2 points being less than 70% B, and C being less than 70% at all concentrations.

  As shown in Table 2, the ink liquid of the present invention was more stable than the comparative ink. In addition, the images obtained from A to E were clearer than the image obtained from the comparative ink liquid 1. Furthermore, images obtained using the ink liquids A to E of the present invention were excellent in light fastness and ozone gas resistance.

  Furthermore, images were recorded on superfine glossy paper (MJA4S3P, Seiko Epson Corp.) using ink liquids A to E by an ink jet printer (PM-700C, Seiko Epson Corp.). When the hue and light fastness of the obtained images were evaluated, the same results as in Table 2 were obtained.

[Example 2]
An image was printed on the inkjet paper photo glossy paper EX manufactured by Fuji Photo Film using the same ink prepared in Example 1, and evaluated in the same manner as in Example 1. Example 1 Similar results were obtained.

[Example 3]
The same ink produced in Example 1 is packed in a cartridge of an inkjet printer BJ-F850 (manufactured by CANON), and an image is printed on the photo glossy paper GP-301 of the same printer, and the same evaluation as in Example 1 is performed. As a result, the same results as in Example 1 were obtained.

Claims (11)

An ink comprising at least one azo dye having a total of more than 12 aromatic conjugated π electrons not directly connected to an azo group , wherein the azo dye is represented by the following general formula (A).
Formula (A): A-N = N-B-N = N-C
In general formula (A),
A represents an aromatic group or a heterocyclic group substituted with a group selected from the group consisting of a sulfo group, a cyano group, and an alkyl group substituted with a sulfo group.
B represents a ring structure represented by the following general formula (2) or (3).
C represents a ring structure represented by the following general formula (1).

R ₅ represents a cyano group, an alkoxycarbonyl group, a carboxyl group or a carbamoyl group.
R ₆ and R ₇ represent an aromatic group or a heterocyclic group substituted with a group selected from the group consisting of a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an alkoxy group, and an acylamino group. .

In the general formula (1), B ₁ and B ₂ are each = CR ₁ - represents a and -CR ₂ =.
R ₁ and R ₂ each independently represents a hydrogen atom, an aliphatic group, or a cyano group.
R ₃ represents an aromatic group, and the aromatic group may be substituted with a sulfo group.
R ₄ represents a hydrogen atom.
G represents an anilino group which may be substituted with a sulfo group. In the following stability test method, the residual ratio of the dye was improved by increasing the amount of the aromatic ring not directly connected to the azo group by an amount corresponding to 6 or more conjugated π electrons to the azo dye having a residual ratio of 60% or less. The ink according to claim 1, comprising at least one azo dye.
Stability test method: Dissolve 0.1 mmol of dye in 10 ml of water, add 84 mg of NaHCO ₃ , heat to reflux for 1 hour, cool, and measure the residual ratio of the dye with a spectrophotometer. Azo dyes, ink according to claim 1 or 2, wherein the water-soluble Jisua zone dyeing cost. The ink according to any one of claims 1 to 3, wherein the azo dye has the following physical property 1.
Physical property 1: When the maximum absorption wavelength of the absorption spectrum measured with a DMF solvent is λmax (DMF), 680 ≧ λmax (DMF) ≧ 570 nm. The ink according to any one of claims 1 to 4, wherein the azo dye has the following property 2.
Physical property 2: The oxidation potential is noble from 1.0 V (vs SCE). Azo dyes, inks according to any one of claims 1 to 5, characterized in that it has the following properties 3.
Physical property 3: | λmax (DMF) −λmax (water) | ≧ 30 nm, where λmax (water) is the maximum absorption wavelength of the absorption spectrum measured with a water solvent. The ink according to any one of claims 1 to 6, wherein the azo dye has the following physical property 4.
Physical property 4: When the molar extinction coefficient in the DMF solvent is ε (DMF) and the molar extinction coefficient in the water solvent is ε (water), ε (water) / ε (DMF) ≦ 0.9. The ink according to any one of claims 1 to 7, wherein the azo dye has the following property 5.
Physical property 5: When λmax (water) is defined as the absorption maximum wavelength of the aggregate, and λmax (DMF) is defined as the absorption maximum wavelength of the monomer, the absorbance at the absorption maximum wavelength of the aggregate in the absorption spectrum in the aqueous solvent is expressed as Abs ( Association), Abs (monomer) / Abs (associate) ≦ 0.75, where Abs (monomer) is the absorbance at the absorption maximum wavelength of the monomer. The ink according to any one of claims 1 to 8, wherein the azo dye contains a nitrogen-containing 6-membered ring. The ink according to any one of claims 1 to 9, wherein the azo dye contains a 5-membered heterocyclic ring. An ink for ink-jet recording using the ink according to any one of claims 1 to 10.