Azo iron complex dyes, ink compositions containing the same, and methods of manufacturing azo iron complex dyes

Abstract

The present invention provides an azo iron complex dye which does not contain harmful heavy metals, has sufficient practical solubility to organic solvents, and exhibits a good black color, the azo iron complex dye being represented by the following formula (1). 【Chem. 1】(In formula (1), R1 and R2 are each independently a linear or branched alkyl group having 3 to 10 carbon atoms, R3 is an electron-withdrawing group, R4 is a linear or branched alkyl group having 1 to 5 carbon atoms or a linear or branched alkoxy group having 1 to 5 carbon atoms, R5 is a nitro group, a sulfonamide group, or a halogen atom, R6 is a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, a nitro group, or a halogen atom, R7 is a hydrogen atom or a linear or branched alkyl group having 3 to 12 carbon atoms, and A+ is a monovalent cation.)

Description

Technical Field

[0001] This invention relates to an azo iron complex dye, an ink composition containing the azo iron complex dye, and a method for preparing the azo iron complex dye. Background Technology

[0002] Ink compositions are used to print or draw handwriting on recording media using inkjet printers, writing instruments, and recorders. Among these, ink compositions for continuous inkjet (CIJ) printers, widely used in industry, have high electrical conductivity because CIJ printers eject the ink composition onto the recording medium while it is charged and deflected. Furthermore, the ink is well fixed on smooth, non-absorbent surfaces such as glass plates, metal plates, and plastic plates. Such ink compositions contain colorants, organic solvents, and resins that act as fixers soluble in the organic solvents.

[0003] Pigments or dyes can be cited as colorants in ink compositions. Black colorants, in particular, are in the highest demand. However, while black pigments show little color change due to light or heat, they lack color development and sometimes aggregate in ink compositions, thus exhibiting poor storage stability. Black dyes, on the other hand, have high solubility in organic solvents and excellent color development and storage stability. However, they also exhibit poor heat and light resistance due to degradation and color change caused by heat or light. Therefore, while maintaining the inherent high solubility of black dyes in organic solvents, black metal complex dyes with high heat and light resistance, similar to black pigments, are used as black colorants.

[0004] In addition, as organic solvents contained in ink compositions, in addition to ketone organic solvents such as acetone and methyl ethyl ketone used in the past, from the point of view of protecting the environment and ensuring safety to the human body, alcohol organic solvents such as ethanol and propylene glycol, and ether organic solvents such as propylene glycol monoalkyl ethers are also used.

[0005] As black dyes with excellent solubility in alcoholic organic solvents, amine salts of azochromium complex dyes are known, for example. Specific examples of such azochromium complex dyes include CISOLVENT BLACK 23, 27, 28, 29, 35, and 45. Furthermore, Patent Document 1 describes a black azochromium complex dye that is soluble in acetone.

[0006] However, because azochromium complex dyes contain chromium, a harmful heavy metal, their use is currently avoided from the perspective of environmental protection and ensuring human safety. Therefore, research is underway to develop metal complex dyes that possess the desirable properties of metal complex dyes while not containing harmful heavy metals like chromium.

[0007] As one such study, Patent Document 2 proposes mixed dyes of iron complexes with three diazo compounds as specific complexing agents. Furthermore, Patent Document 3 describes polyazo-iron complex dyes. However, these iron complex dyes are not black, but rather brown or reddish-brown. On the other hand, Patent Document 4 describes monoazo-iron complex salt compounds. These monoazo-iron complex salt compounds are blackish-purple, less black than the azo-chromium complex dyes.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 51-023518

[0011] Patent Document 2: Japanese Patent Application Publication No. 5-247360

[0012] Patent Document 3: Japanese Patent Publication No. 47-044530

[0013] Patent Document 4: Japanese Patent Application Publication No. 63-4992 Summary of the Invention

[0014] The technical problem that the invention aims to solve

[0015] The present invention was made to solve the above-mentioned problems, and its purpose is to provide an azo iron complex dye that does not contain harmful heavy metals, has sufficient solubility in organic solvents and is black in use, an ink composition containing the azo iron complex dye, and a method for manufacturing the azo iron complex dye.

[0016] Technical means to solve the problem

[0017] The azo iron complex dye invented to achieve the above objectives has an azo-monoazo iron complex represented by the following chemical formula (1).

[0018]

Chemistry 1

[0019]

[0020] (In chemical formula (1), R) 1 and R 2 Each is independently a straight-chain or branched alkyl group having 3 to 10 carbon atoms, R 3 R is an electron-withdrawing group. 4 R is a straight-chain or branched alkyl group having 1 to 5 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 5 carbon atoms. 5 R is a nitro group, a sulfonamide group, or a halogen atom. 6 R is a hydrogen atom, a straight-chain or branched alkyl group, a nitro group, or a halogen atom with 1 to 8 carbon atoms.7 A is a straight-chain or branched alkyl group with 3 to 12 carbon atoms or hydrogen atoms. + It is a monovalent cation.

[0021] In azo iron complex dyes, the R 3 The para-position relative to the azo group, which is attached to the same aromatic ring, is an electron-withdrawing group selected from cyano, nitro, acetyl, sulfonamide, and halogen atoms.

[0022] An azo iron complex dye may be listed, for example, comprising a monoazo-monoazo iron complex represented by the following chemical formula (2).

[0023]

Chemistry 2

[0024]

[0025] (In chemical formula (2), R) 5 ~R 7 and A + Same as chemical formula (1).

[0026] Azo iron complex dyes may contain diazo-diazo iron complexes represented by the following chemical formula (3).

[0027]

Transformation 3

[0028]

[0029] (In chemical formula (3), R1 to R4 and A+ are the same as in chemical formula (1).)

[0030] In azo iron complex dyes, for example, the monovalent cation can be at least one selected from alkali metal ions, ammonium ions, and monovalent alkyl-containing ammonium ions as shown in the following chemical formula (4).

[0031]

Chemistry 4

[0032]

[0033] (In chemical formula (4), R) 8 It is a straight-chain or branched alkyl group having 1 to 18 carbon atoms, R 9 and R 10 (Each alkyl group is independently composed of hydrogen atoms or 1 to 8 carbon atoms, either straight-chain or branched.)

[0034] In the azo iron complex dye, the peak area ratio of the chromatograms obtained by measuring the diazo-monoazo iron complex, the monoazo-monoazo iron complex, and the diazo-diazo iron complex at a wavelength of 254 nm in high performance liquid chromatography can be set to 20-70:5-80:0-50, respectively.

[0035] An ink composition of the present invention contains any of the above-mentioned azo iron complex dyes and organic solvents.

[0036] A method for preparing azo iron complex dyes, comprising an iron complexing step and an ion exchange step, yields a diazo-monozo iron complex as shown in chemical formula (1).

[0037] The iron complexing process involves heating the diazo pigment shown in chemical formula (5), the monoazo pigment shown in chemical formula (6), and the iron-converting agent in a solvent to obtain an azo iron complex anion. The ion exchange process involves reacting the azo iron complex anion with an alkali metal solution and / or an ammonifying agent to introduce a cation that combines with the azo iron complex anion.

[0038]

Transformation 5

[0039]

[0040] (In chemical formula (5), R) 1 and R 2 Each of the following is an independent alkyl group consisting of a straight chain or a branched chain having 3 to 10 carbon atoms: R 3 R is an electron-withdrawing group. 4 It is a straight-chain or branched alkyl group having 1 to 5 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 5 carbon atoms.

[0041]

Transformation 6

[0042]

[0043] (In chemical formula (6), R) 5 R is a nitro group, sulfonamide group, or halogen atom. 6 R is a hydrogen atom, a straight-chain or branched alkyl group, a nitro group, or a halogen atom with 1 to 8 carbon atoms. 7 It is an alkyl group with a straight chain or branched chain, consisting of 3 to 12 hydrogen atoms or carbon atoms.

[0044]

Transformation 7

[0045]

[0046] (In chemical formula (1), R) 1 ~R 4 Similar to chemical formula (5), R 5 ~R 7 Similar to chemical formula (6), A + It is a monovalent cation.

[0047] In the manufacturing method of azo iron complex dye, for example, in the iron complexation process, the molar ratio of the diazo pigment to the monozo pigment can be set to 2:8 to 8:2.

[0048] Invention Effects

[0049] The azo iron complex dye of the present invention does not contain harmful heavy metals such as chromium or cobalt, thus contributing to environmental protection and exhibiting high safety for human health compared to azo chromium complex dyes. Furthermore, because the azo iron complex dye contains an azo iron complex with a specific structure, it exhibits a higher blackness compared to conventional azo iron complex dyes. In addition, the azo iron complex dye of the present invention exhibits practical solubility and stability in various organic solvents, including ketone, alcohol, and ether organic solvents.

[0050] Because the ink composition of the present invention contains the above-mentioned azo iron complex dye, it is highly safe for the environment and human body. It can reliably adhere to the recording medium, whether the ink is absorbent or non-absorbent, without being easily peeled off. Therefore, it can be widely used as a black colorant in various media such as inkjet printers, writing instruments, and recorders.

[0051] According to the method for manufacturing azo iron complex dyes of the present invention, by appropriately selecting substituents that bind to the benzene ring of the azo iron complex ligand or cations that bind to the azo iron complex anion, and by adjusting the molar ratio of diazo pigments that become diazo ligands and monoazo pigments that become monoazo ligands, azo iron complex dyes with both high solubility in various organic solvents and high blackness can be manufactured. Attached Figure Description

[0052] Figure 1 A graph showing the visible absorption spectrum of the azo iron complex dye A-1 using Example 1 of the present invention is shown.

[0053] Figure 2 A graph showing the visible absorption spectrum of the azo iron complex dye A-2 using Example 2 of the present invention is shown.

[0054] Figure 3 A graph showing the visible absorption spectrum of the azo iron complex dye A-3 using Example 3 of the present invention is shown.

[0055] Figure 4 A graph showing the visible absorption spectrum of the azo iron complex dye A-4 using Example 4 of the present invention is shown.

[0056] Figure 5 A graph showing the visible absorption spectrum of the azo iron complex dye A-5 using Example 5 of the present invention is shown.

[0057] Figure 6 A graph showing the visible absorption spectrum of the azo iron complex dye A-6 using Example 6 of the present invention is shown.

[0058] Figure 7 A graph showing the visible absorption spectrum of the azo iron complex dye A-7 using Example 7 of the present invention is shown.

[0059] Figure 8 The visible absorption spectra of the azo iron complex dye A-1 in Example 1 of the present invention and the azo iron complex dyes B-1 to B-3 in Comparative Examples 1 to 3 without the present invention are shown. Detailed Implementation

[0060] The present invention will now be described in detail, but the scope of the invention is not limited to these embodiments. Furthermore, in this specification, "~" generally means that the values ​​described before and after it are included as lower and upper limits.

[0061] (Azo iron complex dye)

[0062] The azo iron complex dye of the present invention has an azo-monoazo iron complex represented by the following chemical formula (1).

[0063]

Transformation 8

[0064]

[0065] (In chemical formula (1), R) 1 and R 2 Each is independently a straight-chain or branched alkyl group having 3 to 10 carbon atoms, R 3 R is an electron-withdrawing group. 4 R is a straight-chain or branched alkyl group having 1 to 5 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 5 carbon atoms. 5 R is a nitro group, a sulfonamide group, or a halogen atom. 6 R is a hydrogen atom, a straight-chain or branched alkyl group, a nitro group, or a halogen atom with 1 to 8 carbon atoms. 7 A is a straight-chain or branched alkyl group with 3 to 12 carbon atoms or hydrogen atoms. + It is a monovalent cation.

[0066] As can be seen from the above chemical formula (1), the diazo-monozo iron complex contained in the azo iron complex dye of the present invention has a structure in which the azo iron complex anion is combined with a monovalent cation. The azo iron complex anion contains trivalent iron and an azo ligand composed of diazo pigment and monozo pigment in a molar ratio of 1:2.

[0067] In chemical formula (1), R1 and R 2 These are straight-chain or branched alkyl groups with 3 to 10 carbon atoms. Specifically, examples include n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,3-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, n-octyl, 2-methylheptyl, 3-methylheptyl, 4... The following compounds are preferred: methylheptyl, 2,2-dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5-dimethylhexyl, 3,3-dimethylhexyl, 3,4-dimethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 2,2,3-trimethylpentyl, 2,2,4-trimethylpentyl, 2,3,3-trimethylpentyl, 2,3,4-trimethylpentyl, 2-methyl-3-ethylpentyl, 3-methyl-3-ethylpentyl, and 2,2,3,3-tetramethylbutyl, n-nonyl, n-decyl, and lauryl. Among these, n-butyl, isobutyl, sec-butyl, tert-butyl, isopentyl, and 2-ethylhexyl are preferred.

[0068] In chemical formula (1), R 3 Electron-withdrawing groups include cyano, nitro, acetyl, sulfonamide, and halogen atoms. Halogen atoms include fluorine, chlorine, bromine, and iodine. When R... 3 When these electron-withdrawing groups are present, the darkening effect of the azo iron complex dye is improved, resulting in a practically sufficient deep black. R 3 When the azo group is attached to the para position on the same aromatic ring, it is preferred from the viewpoint of darkening.

[0069] Such a diazo-monazo iron complex is specifically represented by the following chemical formula (7).

[0070]

Chemistry 9

[0071]

[0072] (In chemical formula (7), R) 1 ~R 7 and A + Same as chemical formula (1).

[0073] In chemical formula (1), R 4It is a straight-chain or branched alkyl group having 1 to 5 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 5 carbon atoms. Specific examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, and neopentyl. Specific examples of such alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, and neopentoxy.

[0074] Such a diazo-monazo iron complex is specifically represented by the following chemical formula (8).

[0075]

Chemistry 10

[0076]

[0077] (In chemical formula (8), R) 1 ~R 7 and A + Same as chemical formula (1).

[0078] In chemical formula (1), R 5 It is an electron-withdrawing substituent such as a nitro group, sulfonamide group, or halogen atom. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. If the azo group on the bonded aromatic ring is incorporated at the 4th or 5th position, the blackness of the diazo-monoazo iron complex can be further improved, resulting in a practically sufficient deep black color; therefore, R is preferred. 5 .

[0079] In chemical formula (1), R 6 It is a straight-chain or branched alkyl, nitro, or halogen atom with hydrogen atoms and 1 to 8 carbon atoms. Examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,3-dimethylpentyl, 3-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, n-octyl, 2 -Methylheptyl, 3-methylheptyl, 4-methylheptyl, 2,2-dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5-dimethylhexyl, 3,3-dimethylhexyl, 3,4-dimethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 2,2,3-trimethylpentyl, 2,2,4-trimethylpentyl, 2,3,3-trimethylpentyl, 2,3,4-trimethylpentyl, 2-methyl-3-ethylpentyl, 3-methyl-3-ethylpentyl, and 2,2,3,3-tetramethylbutyl. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0080] Such diazo-monadizo iron complexes are specifically represented by the following chemical formulas (9a) and (9b).

[0081]

Chemistry 11

[0082]

[0083] (In chemical formula (9a), R) 1 ~R 7 and A + Same as chemical formula (1).

[0084]

Chemistry 12

[0085]

[0086] (In chemical formula (9b), R) 1 ~R 7 and A + Same as chemical formula (1).

[0087] In chemical formula (1), R 7 It is a straight-chain or branched alkyl group having 3 to 12 hydrogen atoms or carbon atoms. Examples of such alkyl groups include n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,3-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, n-octyl, tert-octyl, 2-methylheptyl, 3-methylheptyl, 4 The following compounds are preferred: methylheptyl, 2,2-dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5-dimethylhexyl, 3,3-dimethylhexyl, 3,4-dimethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 2,2,3-trimethylpentyl, 2,2,4-trimethylpentyl, 2,3,3-trimethylpentyl, 2,3,4-trimethylpentyl, 2-methyl-3-ethylpentyl, 3-methyl-3-ethylpentyl, and 2,2,3,3-tetramethylbutyl, n-nonyl, n-decyl, lauryl, and dodecyl. Among these, tert-butyl, isopentyl, hexyl, n-octyl, tert-octyl, 2-ethylhexyl, n-nonyl, n-decyl, and dodecyl are preferred.

[0088] Such diazo-monadizo iron complexes are specifically represented by the following chemical formulas (10a), (10b), (10c), and (10d).

[0089]

Chemistry 13

[0090]

[0091] (In chemical formula (10a), R) 1 ~R 7 and A + Same as chemical formula (1). ) [Chemistry 14]

[0092]

[0093] (In chemical formula (10b), R) 1 ~R 7 and A + Same as chemical formula (1). ) [Chemistry 15]

[0094]

[0095] (In chemical formula (10c), R) 1 ~R 7 and A + Same as chemical formula (1).

[0096]

Chemistry 16

[0097]

[0098] (In the chemical formula (10d), R) 1 ~R 7 and A + Same as chemical formula (1).

[0099] In chemical formula (1), A + It is a monovalent cation. Examples of monovalent cations include hydrogen ions, alkali metal ions, and ammonium ions (NH4+). + ) and ammonium ions containing monovalent alkyl groups. The diazo-monazo iron complex may contain only one or more of these monovalent cations. Among them, ammonium ions and ammonium ions containing monovalent alkyl groups are preferred. Examples of alkali metal ions include lithium ions (Li... + Sodium ions (Na) + ) and potassium ions (K + Alkali metal ions can originate from pH adjusters used in the synthesis of diazo-monozo iron complexes. Furthermore, monovalent cations can bind to only one iron complex anion, or multiple cations can bind to the iron complex anion.

[0100] Ammonium ions containing monovalent alkyl groups are represented by the following chemical formula (4).

[0101]

Chemistry 17

[0102]

[0103] In chemical formula (4), R 8 It is a straight-chain or branched alkyl group having 1 to 18 carbon atoms, R 9 and R 10 Each is independently a straight-chain or branched alkyl group having 1 to 8 carbon atoms. As R 7 Alkyl groups, including methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,3-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, n-octyl, 2-methylheptyl, 3-methylheptyl, 4-methyl The alkyl group comprises heptyl, 2,2-dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5-dimethylhexyl, 3,3-dimethylhexyl, 3,4-dimethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 2,2,3-trimethylpentyl, 2,2,4-trimethylpentyl, 2,3,3-trimethylpentyl, 2,3,4-trimethylpentyl, 2-methyl-3-ethylpentyl, 3-methyl-3-ethylpentyl, and 2,2,3,3-tetramethylbutyl, n-nonyl, n-decyl, undecyl, lauryl, and stearyl. Preferably, the alkyl group comprises a straight-chain or branched alkyl group having 7 to 18 carbon atoms; more preferably, a branched alkyl group having 8 to 15 carbon atoms; and even more preferably, a branched alkyl group having 11 to 14 carbon atoms.

[0104] In chemical formula (4), as R 9 and R 10 Alkyl groups, specifically, include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-heptyl, and n-octyl. Methyl is preferred.

[0105] The azo iron complex dye of the present invention requires a diazo-monozo iron complex, which, by having an asymmetric structure comprising a diazo ligand and a monozo ligand, darkens the azo iron complex dye, absorbs wavelengths in the visible light region, and exhibits a practically deep black color. The aforementioned diazo ligand comprises an amino group (in chemical formula (1) -NR) bonded to a dialkyl group having a specific range of carbon atoms. 1 R 2 ) and electron-withdrawing groups (same as -R) 3 The above-mentioned monoazo ligands have the same electron-withdrawing group (same -R). 5 and / or -R 6 ).

[0106] Furthermore, the aromatic ring of the diazo ligand consists only of arylene groups and does not contain a naphthalene ring, which is the reason for its large size and high molecular weight. Therefore, this azo-iron complex dye has a lower molecular weight compared to azo-iron complex dyes with diazo ligands containing a naphthalene ring, and thus exhibits high color development even in small quantities.

[0107] Furthermore, this diazo-monoazo iron complex enhances the solubility of the black azo iron complex anion by using monovalent alkylammonium ions containing alkali metal ions, ammonium ions, and / or alkyl groups with a specific range of carbon atoms as cations. Therefore, the azo iron complex dye of this invention exhibits higher solubility in alcoholic organic solvents such as ethanol and ethylene glycol, and ketone organic solvents such as methyl ethyl ketone, making it practical for ink compositions. It also possesses high solubility stability, thus preventing precipitation in organic solvents. Therefore, this azo iron complex dye is suitable for ink compositions, particularly ink compositions for continuous inkjet printers. Moreover, the azo iron complex dye does not contain the environmentally and human-harming heavy metals chromium and cobalt, thus contributing to environmental protection and ensuring human safety.

[0108] In addition to having a diazo-monodiazo iron complex as shown in chemical formula (1), the azo iron complex dye of the present invention preferably further includes a monodiazo-monodiazo iron complex having only a monodiazo ligand as a ligand of the diazo-monodiazo iron complex, and / or a diazo-diazo iron complex having only a diazo ligand.

[0109] The monoazo-monazo iron complex is represented by the following chemical formula (2).

[0110] [Chemistry 18]

[0111]

[0112] (In chemical formula (2), R) 5 ~R 7 and A + Same as chemical formula (1).

[0113] In addition, the diazo-diazo iron complex is represented by the following chemical formula (3).

[0114]

Chemistry 19

[0115]

[0116] (In chemical formula (3), R) 1 ~R 4 and A + Same as chemical formula (1).

[0117] When azo iron complex dyes contain diazo-monoazo iron complexes (DM), monoazo-monoazo iron complexes (MM), and diazo-diazo iron complexes (DD), their molar ratios are specific to a particular wavelength, for example, and can be expressed as the peak area ratio in a chromatogram obtained by high-performance liquid chromatography at a wavelength of 254 nm. Specifically, DM:MM:DD = 20–70:5–80:0–50, more preferably 20–65:5–80:0–50, even more preferably 20–60:20–80:0–30, and even more preferably 20–55:20–80:0–15. Furthermore, the lower limit value for DD can be 1 instead of 0. Additionally, the above values ​​are expressed by rounding the peak area ratio to one decimal place; for example, the expression of 0 as the lower limit value for DD includes values ​​greater than 0.0, i.e., values ​​from 0.1 to 0.4.

[0118] When an azo iron complex dye, in addition to being an asymmetric azo iron complex diazo-monozo iron complex, further contains a symmetric azo iron complex dye such as a monoazo-monozo iron complex having only a monoazo ligand and / or a diazo-diazo iron complex having only a diazo ligand, the blackness, solubility, and solubility stability of the azo iron complex dye, and consequently the conductivity required for ink compositions for continuous inkjet (CIJ) printers, can be appropriately and arbitrarily adjusted by keeping the ratio of each azo iron complex within an appropriate range. Therefore, this is preferred.

[0119] The azo iron complex dye of the present invention is suitable for ink compositions for CIJ printers. In this case, the conductivity K of the azo iron complex dye is preferably 300–2200 μS / cm, more preferably 600–2000 μS / cm. If the conductivity is within this range, the charge of the CIJ printer ink composition containing the azo iron complex dye can be stably and freely controlled, thus improving the inkjet stability of the ink composition. Furthermore, this conductivity K is measured by inserting the electrode of a conductivity meter into a 6% (w / w) methyl ethyl ketone solution of the azo iron complex dye and immersing it in the solution.

[0120] The alkali metal ion content of the azo iron complex dye is preferably below 1000 ppm, more preferably below 500 ppm. This reduces the surface tension of the ink composition, thus making it suitable for CIJ printers.

[0121] Furthermore, when additives such as leveling agents or anti-sticking agents in the CIJ printer ink composition contain silicone compounds or silicone-based surfactants, the formation of complexes between these silicone compounds and silicone-based surfactants and alkali metal ions can be suppressed if the content of alkali metal ions in the azo iron complex dye is within the aforementioned range. This prevents printhead clogging and improves the inkjet stability of the CIJ printer ink composition.

[0122] In order to obtain an azo iron complex dye containing the azo iron complex shown in chemical formulas (1) to (3), it is preferable to use a manufacturing method having the following steps 1 to 5.

[0123] Step 1: Obtaining diazo pigments using a diazo coupling reaction.

[0124] Step 2: Obtaining monoazo pigments using a diazo coupling reaction.

[0125] Step 3: The process of complexing the mixture of diazo dyes and monoazo dyes with iron to obtain azo-iron complex dyes.

[0126] Step 4: The process of modifying and preparing azo iron complex dye cations.

[0127] Step 5: The process of filtering, washing, drying, and pulverizing the azo iron complex dye.

[0128] This manufacturing method can yield high-purity azo iron complex dyes. The following details each step of the process.

[0129] Step 1: Obtaining diazo pigments using a diazo coupling reaction.

[0130] The first step is to obtain a diazo dye that can act as a diazo ligand in an azo iron complex.

[0131] (1-1: Synthesis of monoazo compounds)

[0132] First, as shown in the following chemical formula (11), a specific aromatic amine is diazotized using a known method and then diazo-coupled with 2-aminophenol by a conventional method to obtain a monoazo compound as an intermediate for a diazo dye.

[0133]

Chemistry 20

[0134]

[0135] (In chemical formula (11), R) 3 and R 4 Same as chemical formula (1).

[0136] In the reaction of chemical formula (11), specifically, for example, an aqueous solution of aminobenzene (diazo component) prepared with electron-withdrawing substituents diluted with hydrochloric acid and sodium nitrite (e.g., 40% by mass aqueous solution) are added to ion-exchanged water or a mixture of ion-exchanged water and lower alcohol, and the aminobenzene is diazotized by stirring at a temperature of 0–5°C for 1–3 hours to obtain a diazotized solution. Excess nitrite is decomposed with aminosulfonic acid or the like.

[0137] Next, aminophenol with substituents such as hydroxyl groups suitable for metal complex salt formation is dissolved or finely dispersed in an aqueous solution prepared by dilution with hydrochloric acid. A diazotization solution is added dropwise to this solution, and a diazo coupling reaction is carried out in a hydrophilic solvent or a water-lower alcohol solvent at room temperature or low temperature for several hours to obtain a solution containing a monoazo compound. The monoazo compound is filtered and washed with water to obtain a wet filter cake containing the monoazo compound. In the next step of synthesizing diazo pigments, the wet filter cake can be dried before use, or the wet filter cake can be used directly, or the solution containing the monoazo compound can be used directly.

[0138] (1-2: Synthesis of diazo dyes)

[0139] As shown in the following chemical formula (12), the monoazo compound obtained above is diazotized by a known method and then diazo-coupled with an aminophenol compound having a specific alkyl amino group by a conventional method to obtain a solution containing a diazo dye.

[0140]

Chemistry 21

[0141]

[0142] (In chemical formula (12), R) 1 ~R 4 Same as chemical formula (1).

[0143] In the reaction of chemical formula (12), specifically, for example, an aqueous solution of the monoazo compound obtained in the above-mentioned monoazo compound synthesis, diluted with hydrochloric acid, and sodium nitrite (e.g., a 40% by mass aqueous solution) are added to ion-exchanged water or a ion-exchanged water-lower alcohol mixed solvent. The amino group is diazotized by stirring at a temperature of 0–5°C for 1–3 hours to obtain a diazotized solution. Excess nitrite is decomposed using aminosulfonic acid or the like.

[0144] Next, aminophenol with substituents such as hydroxyl groups suitable for metal complex salt formation is dissolved or finely dispersed in an alkaline aqueous solution. A diazotization solution is added dropwise to this solution, and a diazo coupling reaction is carried out in a hydrophilic solvent or a water-lower alcohol solvent at room temperature or low temperature for several hours to obtain a solution containing a diazo dye. The diazo dye is filtered and washed with water to obtain a wet filter cake of the diazo dye. In the subsequent iron complexation step, the wet filter cake can be dried before use, or the wet filter cake can be used directly, or the solution containing the diazo dye can be used directly.

[0145] Step 2: Obtaining monoazo pigments using a diazo coupling reaction.

[0146] The second step is to obtain a monoazo pigment that can serve as a monoazo ligand in an azo iron complex.

[0147] First, an aromatic amine having electron-withdrawing groups such as nitro or halogen atoms is diazotized using a known method to obtain a diazotized solution. Specifically, for example, an aqueous solution of an electron-withdrawing substituent aminobenzene (diazo component) prepared by diluting it with hydrochloric acid and sodium nitrite (e.g., a 40% by mass aqueous solution) are added to ion-exchanged water or a mixture of ion-exchanged water and a lower alcohol. The aminobenzene is then diazotized by stirring at 0–5°C for 1–3 hours to obtain a diazotized solution. Excess nitrite is then decomposed using aminosulfonic acid or the like.

[0148] Then, as shown in the following chemical formula (13), the diazo compound and 2-naphthol in the diazotized solution obtained above are subjected to a diazo coupling reaction by conventional methods to obtain a monoazo pigment.

[0149]

Chemistry 22

[0150]

[0151] (In chemical formula (13), R) 5 ~R 7 Same as chemical formula (1).

[0152] The reaction of chemical formula (13) is carried out as follows. 2-Naphthol is dissolved or finely dispersed in an alkaline aqueous solution. A diazotization solution is added dropwise to the solution. The diazotization coupling reaction is carried out in a hydrophilic solvent or a water-lower alcohol solvent at room temperature or low temperature for several hours to obtain a solution containing a monoazo pigment. The monoazo pigment is filtered and washed with water to obtain a wet filter cake containing the monoazo pigment. In the iron complexation step, which is the next step, the wet filter cake can be dried before use, or the wet filter cake can be used directly, or the solution containing the monoazo pigment can be used directly.

[0153] Step 3: The process of complexing the mixture of diazo pigments and monoazo pigments with iron to obtain an azo-iron complex.

[0154] The third step is an iron complexation step, which involves iron-converting the diazo pigments and monoazo pigments obtained in the above steps to obtain azo iron complexes (azo iron complex anions).

[0155] The diazo pigment obtained in step 1 and the monoazo pigment obtained in step 2 are added in a molar ratio of, for example, 2:8, and mixed to obtain a mixed pigment. The mixed pigment is dispersed or dissolved in a solvent, and then an iron-coating agent is added. The mixture is heated and stirred at 80–140°C for 1–5 hours. Thus, as shown in the following chemical formula (14), an iron-coating reaction is carried out to coordinate the diazo pigment and the monoazo pigment on the iron atom, resulting in a mixture of the diazo-monazo iron complex shown in chemical formula (1), the monoazo-monazo iron complex shown in chemical formula (2), and the diazo-diazo iron complex shown in chemical formula (3).

[0156]

Chemistry 23

[0157]

[0158] (In chemical formula (14), R) 1 ~R 7 Same as chemical formula (1), X + (It can be any cation.)

[0159] The preferred molar ratio of diazo pigment to monoazo pigment is 2:8 to 8:2, specifically examples include 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, and 8:2. A diazo pigment : monoazo pigment ratio of 2:8 to 5:5 results in high blackness and exhibits high solubility relative to the organic solvents contained in the ink composition, and is therefore preferred.

[0160] Examples of solvents used in the iron complexation process include water, water-organic solvent mixtures, and organic solvents, with water-organic solvent mixtures being preferred. Examples of organic solvents include alcohols, glycols, amides, ethers, ketones, sulfoxides, and aromatic hydrocarbons, with alcohols, glycols, amides, and sulfoxides being preferred.

[0161] Preferred organic solvents include alcohols such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, benzyl alcohol, cyclohexanol, and diacetone alcohol; diethanolalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and dipropylene glycol monoethyl ether; diethanol acetates such as ethylene glycol monoacetate and propylene glycol monoacetate; diol solvents such as ethylene glycol, diethylene glycol, trimethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, and butanediol; and amide solvents such as N-methylformamide, N,N-dimethylformamide, N-ethylformamide, N,N-diethylformamide, N-methylacetamide, and N,N-dimethylacetamide. Sulfoxide solvents include sulfoxide, 3-methyl sulfoxide, and dimethyl sulfoxide. Amide solvents are preferred.

[0162] The ferricizing agents used in the iron complexation process include ferric sulfate, ferrous sulfate, ferric chloride, ferrous chloride, ferric nitrate, ferric acetate, and ferric lactate. The equivalent number of the ferricizing agent is preferably 1 / 2 to 2, more preferably 1 / 2 to 2 / 3, relative to the total equivalent number of the diazo and monoazo pigments. Furthermore, the ferricization reaction is preferably carried out at a temperature suitable for the type of solvent used, while heating (including reflux stirring). The ferricization reaction can be carried out with the addition of additives such as reaction promoters and pH adjusters. By adjusting the pH by adding acid or alkali, any cation X that combines with the azo iron complex anion during the reaction can be prepared. + The desired cation A+ is, for example, hydrogen ion, sodium ion, potassium ion, ammonium ion, monovalent alkyl-containing ammonium ion, or a mixture of these cations.

[0163] In this third step, an example is shown where the diazo pigment obtained in the first step is mixed with the monoazo pigment obtained in the second step and then subjected to an iron-reaction reaction. However, the third step is not limited to this. Diazo pigments or monoazo pigments can be added to the solvent, followed by the sequential addition of monoazo pigments or diazo pigments. An iron-reacting agent can also be added to carry out the iron-reaction reaction with ferric iron. Alternatively, diazo pigments or monoazo pigments can be added to the solvent, followed by the addition of an iron-reacting agent, and after the iron-reaction reaction, monoazo pigments or diazo pigments can be added. Further iron-reacting agents can be added as needed to carry out the iron-reaction reaction with ferric iron. In this case, the remaining portion of the azo pigment that has undergone the iron-reaction reaction and other subsequently added azo pigments form a diazo-monazo-iron complex through the iron-reaction reaction.

[0164] Furthermore, diazo dyes and monoazo dyes can be used individually, or multiple dyes with different substituents or different binding positions of the substituents can be used in combination. For example, two monoazo dyes can be mixed with one diazo dye, or one monoazo ligand can be used in combination with two diazo dyes.

[0165] Step 4: The process of modifying and preparing azo iron complex dye cations.

[0166] In step 4, the process of changing and preparing the cation of the azo iron complex dye, for example, by using an alkali metal solution, an ammonium aqueous solution and / or a monovalent amine having alkyl atoms of 3 to 18, to iron complex the mixture of azo dyes to obtain the azo iron complex dye, involves exchanging the cation of the azo iron complex dye obtained in the process of iron complexing the mixture of azo dyes with the desired cation.

[0167] For example, if the cation of the azo iron complex dye obtained in the above process is a hydrogen ion or an alkali metal ion, these cations are exchanged using an ammonifying agent. Through this cation exchange reaction, as shown in the following chemical formula (15), an azo iron complex dye with introduced ammonium cations is obtained.

[0168]

Chemistry 24

[0169]

[0170] (In chemical formula (15), R) 1 ~R 7 Similar to chemical formula (1), R 8 ~R 10 Same as chemical formula (4), X + (It can be any cation.)

[0171] Ammonizing agents include aqueous solutions of ammonium and monovalent amine compounds with alkyl groups having 3 to 18 carbon atoms. Only one ammonizing agent may be used, or multiple agents may be used in combination.

[0172] By combining various conditions such as the amount of acid, base, ammonifying agent, and reaction temperature used for cation exchange, azo iron complexes with mixed ions as cations can be obtained. Azo iron complexes in which 86 mol% or more, particularly 90 mol% or more, of the cations in the mixed ions are the desired ammonium ions can be obtained.

[0173] The cation exchange reaction in step 4 can be carried out simultaneously or sequentially in the same reaction system as the ironing reaction in step 3. Alternatively, step 4 can be performed by adding an ammonifying agent along with an organic solvent when preparing the ink composition.

[0174] Step 5: The process of filtering, washing, drying, and pulverizing the azo iron complex dye.

[0175] The fifth step is performed as needed after the third or fourth step, and may include filtration, washing, drying and pulverizing steps.

[0176] The filtration step involves separating the reaction solution containing azo iron complex dye, obtained in the third step (or subsequent alkali treatment) or ion exchange step, into a wet filter cake of azo iron complex dye by filtration, resulting in a solid residue of the azo iron complex dye and a solvent. Filtration methods include heavy-pressure filtration such as paper filtration, bag filtration, and centrifugation; vacuum filtration using filters such as Buchner suction funnels, leaf filters, disc filters, drum filters, and Oliver filters; and pressure filtration using filter presses, closed leaf filters, and closed multi-stage filters.

[0177] After the filtration process, a cleaning process can also be performed. The wet filter cake containing the azo iron complex or azo iron complex dye is thoroughly washed with a cleaning solution. Examples of cleaning solutions include water and organic solvents, with water being preferred. The wet filter cake can also be used directly as an intermediate for the next process.

[0178] Following the washing process, a drying process can be performed to dry the wet filter cake of the azo iron complex dye. A drying process can also be performed as needed. The dried, lumpy azo iron complex dye can be broken down or pulverized using a known pulverizer to achieve the desired particle size.

[0179] More detailed examples of azo iron complex dyes of the present invention, having diazo-monoazo iron complexes (DM), monoazo-monoazo iron complexes (MM), and diazo-diazo iron complexes (DD), respectively, as well as azo iron complex dyes of combinations of these ligands, are described below.

[0180] (Diazo ligand)

[0181] The diazo ligand (D ligand) that serves as the ligand for the azo iron complex dye of the present invention is specifically represented by the following chemical formula (16).

[0182]

Chemistry 25

[0183]

[0184] (In chemical formula (16), R) 1 and R 2 Similar to chemical formula (1), R 3a ~R 3c One of them is an electron-withdrawing group selected from cyano, nitro, acetyl, sulfonamide, and halogen atoms, and the others are hydrogen atoms, R 4a ~R 4c (Each of the following is a straight-chain or branched alkyl group having 1 to 5 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 5 carbon atoms; the others are hydrogen atoms.)

[0185] In chemical formula (16), R1 R 2 R 3a ~R 3c and R 4a ~R 4c The specific substituents are shown in Table 1.

[0186] Table 1

[0187] Table 1

[0188] D ligand <![CDATA[R 1 ]]> <![CDATA[R 2 ]]> <![CDATA[R 3a ]]> <![CDATA[R 3b ]]> <![CDATA[R 3c ]]> <![CDATA[R 4a ]]> <![CDATA[R 4b ]]> <![CDATA[R 4c ]]> D1 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H H CN H <![CDATA[CH3]]> H D2 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H H <![CDATA[NO2]]> H <![CDATA[CH3]]> H D3 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H H <![CDATA[COCH3]]> H <![CDATA[CH3]]> H D4 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H H <![CDATA[SO2NH2]]> H <![CDATA[CH3]]> H D5 <![CDATA[tert-C4H9]]> <![CDATA[tert-C4H9]]> H H CN H <![CDATA[CH3]]> H D6 <![CDATA[iso-C3H7]]> <![CDATA[iso-C3H7]]> H H CN H <![CDATA[CH3]]> H D7 <![CDATA[tert-C8H 17 ]]> <![CDATA[tert-C8H 17 ]]> H CN H H <![CDATA[OCH3]]> H D8 <![CDATA[sec-C4H9]]> <![CDATA[sec-C4H9]]> H H <![CDATA[NO2]]> H <![CDATA[C2H5]]> H D9 <![CDATA[iso-C3H7]]> <![CDATA[iso-C3H7]]> H H CN H <![CDATA[OCH3]]> H D10 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H <![CDATA[COCH3]]> H H <![CDATA[C2H5]]> H D11 2-EtHx 2-EtHx H H <![CDATA[SO2NH2]]> H <![CDATA[CH3]]> H D12 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H H CN H <![CDATA[OCH3]]> H D13 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H CN H H <![CDATA[OCH3]]> H D14 <![CDATA[iso-C5H 11 ]]> <![CDATA[iso-C5H 11 ]]> H H <![CDATA[COCH3]]> H <![CDATA[C3H7]]> H D15 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H H Cl H <![CDATA[OC2H5]]> H D16 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> <![CDATA[NO2]]> H H H <![CDATA[CH3]]> H D17 <![CDATA[iso-C3H7]]> <![CDATA[iso-C3H7]]> H H <![CDATA[SO2NH2]]> H <![CDATA[C2H5]]> H D18 2-EtHx 2-EtHx H CN H H <![CDATA[OCH3]]> H D19 <![CDATA[n-C4H9]]> <![CDATA[n-C4H9]]> H <![CDATA[NO2]]> H H <![CDATA[OCH3]]> H D20 <![CDATA[tert-C8H 17 ]]> <![CDATA[tert-C8H 17 ]]> H <![CDATA[COCH3]]> H H <![CDATA[CH3]]> H

[0189] (Monoazo ligand)

[0190] The monoazo ligand (M ligand) that serves as the ligand for the azo iron complex dye of the present invention is specifically represented by the following chemical formula (17).

[0191]

Chemistry 26

[0192]

[0193] (In chemical formula (17), R) 5a and R 5b Each of the following groups is independently composed of a hydrogen atom, a nitro group, a sulfonamide group, or a halogen atom; R 6a and R 6b Each atom is independently hydrogen, and the number of carbon atoms is 1 to 8, which are straight-chain or branched alkyl groups, nitro groups, or halogen atoms. 7a ~R 7f (Each is independently a straight-chain or branched alkyl group having 3 to 12 hydrogen atoms or carbon atoms.) Additionally, R is preferred. 5a R 5b R 6a R 6b All substituents are not the same at the same time, R is preferred. 7a ~R 7f One of them is an alkyl group, and the rest are all hydrogen atoms.

[0194] In chemical formula (17), R 5a R 5b R 6a R 6b and R 7a ~R 7f The specific substituents are shown in Table 2.

[0195] Table 2

[0196] Table 2

[0197] M ligand <![CDATA[R 5a ]]> <![CDATA[R 5b ]]> <![CDATA[R 6a ]]> <![CDATA[R 6b ]]> <![CDATA[R 7a ]]> <![CDATA[R 7b ]]> <![CDATA[R 7c ]]> <![CDATA[R 7d ]]> <![CDATA[R 7e ]]> <![CDATA[R 7f ]]> M1 <![CDATA[NO2]]> H H H H H H H H H M2 H <![CDATA[NO2]]> H <![CDATA[NO2]]> H H H H H H M3 <![CDATA[tert-C4H9]]> <![CDATA[NO2]]> H <![CDATA[NO2]]> H H H H H H M4 Cl H H H H H H H H H M5 H Br H Br H H H H H H M6 <![CDATA[NO2]]> <![CDATA[tert-C8H 17 ]]> H <![CDATA[tert-C8H 17 ]]> H H H H H H M7 <![CDATA[iso-C5H 11 ]]> H <![CDATA[NO2]]> H H H H H H H M8 Cl H Cl H H H H H H H M9 <![CDATA[NO2]]> H Cl H H H H H H H M10 <![CDATA[NO2]]> H <![CDATA[NO2]]> H H H H H H H M11 <![CDATA[tert-C4H9]]> <![CDATA[NO2]]> H H H H H H H H M12 Cl H H H H H <![CDATA[tert-C8H 17 ]]> H H H M13 <![CDATA[NO2]]> H H H H H <![CDATA[tert-C4H9]]> H H H M14 H <![CDATA[NO2]]> H H H H H H <![CDATA[n-C3H7]]> H M15 H Cl H H H H H H <![CDATA[n-C3H7]]> H M16 H <![CDATA[SO2NH2]]> H H H H H H H H

[0198] The azo iron complex dye of the present invention is represented by the above chemical formula (16), specifically, for example, by at least one diazo ligand (D ligand) with substituents shown in Table 1 and the above chemical formula (17), specifically, for example, at least one monoazo ligand (M ligand) shown in Table 2 comprises at least 1 mole of diazo-monazo iron complex (DM body) respectively coordinated on iron atoms.

[0199] Azo iron complex dyes are further added to the DM body, represented by the above chemical formula (17). Specifically, for example, they can be represented by the monoazo-monazo iron complex (MM body) formed by at least 2 moles of M ligands coordinated to 1 mole of iron atoms as shown in Table 2, and by the above chemical formula (16). Specifically, for example, they can also include 2 moles of at least one D ligand having the substituents shown in Table 1 coordinated to 1 mole of iron atoms to form a diazo-diazo iron complex (DD body). The ratio of each azo iron complex type in these azo iron complex dyes, the types of D ligands and M ligands they have, and the addition and mixing of diazo pigments (D pigments) and monoazo pigments (M pigments) used to obtain each azo iron complex dye are shown in Table 3. In addition, in Table 3, the symbols in the D ligand and M ligand columns correspond to those in Tables 1 and 2.

[0200] Table 3

[0201] Table 3

[0202]

[0203] (Ink composition)

[0204] The ink composition of the present invention contains an azo iron complex dye and an oily liquid medium as an organic solvent. The azo iron complex dye content in the ink composition is preferably 3 to 25% by mass, more preferably 5 to 15% by mass, and even more preferably 5 to 10% by mass. Furthermore, examples of organic solvents include ketone organic solvents, alcohol organic solvents, and ether organic solvents, with ketone organic solvents and alcohol organic solvents being preferred.

[0205] Examples of ketone organic solvents include lower alkyl ketones such as acetone, methyl ethyl ketone, dipropyl ketone, methyl isobutyl ketone, and methyl isopropyl ketone; and cyclic ketones such as cyclohexanone. Among these, methyl ethyl ketone exhibits good resin solubility, pigment dispersibility, conductivity, and ink drying properties, making it suitable for ink compositions used in continuous inkjet printers.

[0206] Examples of alcohol-based organic solvents include lower alkyl alcohols such as methanol, ethanol, propanol, isopropanol, and butanol; and diols such as dioxane, ethylene glycol, diethylene glycol, and triethylene glycol.

[0207] Ether organic solvents include glycol ethers and their esters. Specifically, examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monophenyl glycol, ethylene glycol monobenzyl glycol, ethylene glycol dimethyl ether, and ethylene glycol diethyl ether, such as ethylene glycol alkyl ethers; and diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monophenyl glycol, diethylene glycol monobenzyl glycol, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, such as diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monophenyl glycol, diethylene glycol monobenzyl glycol, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, such as diethylene glycol monomethyl ether. Glycol alkyl ethers; triethylene glycol alkyl ethers such as triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether and triethylene glycol diethyl ether; propylene glycol alkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and propylene glycol monophenyl ether; dipropylene glycol alkyl ethers such as dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monopropyl ether and dipropylene glycol monopropyl ether; tripropylene glycol alkyl ethers such as tripropylene glycol monomethyl ether and tripropylene glycol monobutyl ether.

[0208] In addition to the above, other organic solvents that can be cited include ester organic solvents such as ethyl acetate, ethyl propionate, ethyl lactate, propyl acetate, and butyl acetate; and aromatic hydrocarbon organic solvents such as toluene and xylene.

[0209] The above-mentioned organic solvents can be used alone or in combination.

[0210] The ink composition of the present invention may contain a resin soluble in the aforementioned organic solvents. Specifically, examples include cellulose resins, styrene-acrylic resins, terpene phenolic resins, polyvinyl butyral resins, ketone resins, maleic acid resins, rosin resins, acrylic resins, styrene-maleic acid resins, polyvinyl alcohol resins, rosin ester resins, silicone resins, phenolic resins, coumarone-indene resins, phenolic resins, aldehyde resins, polyester resins, polyamide resins, polyimide resins, terpene resins, alkyd resins, polyurethane resins, acetal resins, epoxy resins, urea resins, melamine resins, and xylene resins. These resins may be used alone or in combination.

[0211] Specifically, the aforementioned cellulose-based resins include nitrocellulose; lower acyl-substituted derivatives such as cellulose propionate, cellulose butyrate, cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate; lower alkyl-substituted derivatives such as methylcellulose and ethylcellulose; nitrocellulose; and hydroxypropylcellulose.

[0212] These cellulose resins exist in a wide variety of types depending on the degree of substitution of the hydroxyl groups and their molecular weight. The cellulose resin is appropriately selected based on the viscosity required for the ink composition. Examples include cellulose esters obtained by modifying all or part of the hydroxyl groups of the cellulose resin with one or more esters having 2-8 carbon atoms, preferably 2-5. Specifically, lower acyl-substituted cellulose derivatives such as cellulose acetate propionate and cellulose acetate butyrate are preferred. Cellulose acetate butyrate esters are particularly preferably substituted with a degree of substitution of 2-20% for acetyl and 32-53% for butyryl. Furthermore, cellulose acetate propionate esters are particularly preferably substituted with a degree of substitution of 0.5-10% for acetyl and 35-55% for propionyl. The degree of substitution is defined as 100% when all three hydroxyl groups of one unit of glucose are substituted.

[0213] Styrene-acrylic resin is a copolymer of styrene monomers and acrylic monomers, preferably with an acid value of 120 or less and a molecular weight of 3,000 to 30,000. Examples of styrene monomers include styrene, α-methylstyrene, and vinyltoluene. Examples of acrylic monomers include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, amyl acrylate, amyl methacrylate, hexyl acrylate, hexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl methacrylate.

[0214] Styrene-acrylic resins are available on the market, such as: JONCRYL (registered trademark) 68, 586 and 611 (manufactured by BASF Corporation), Himer (registered trademark) SBM-100 and Himer SAM-955 (manufactured by Sanyo Chemical Co., Ltd.), Nigarite (registered trademark) NC-6531, and Nikkalite NC-6100 (manufactured by Carbide Corporation of Japan).

[0215] Terpene phenolic resins are copolymers of terpenes such as α-pinene, β-pinene, and dipentene with phenols such as phenol and bisphenol. After selecting the monomers according to the requirements of the ink composition, the molar ratio of each monomer is set. Terpene phenolic resins are commercially available, such as YP90 and YP90L; YS polymers S145, #2100, #2115, #2130, T80, T100, T115, T130, and T145; and MightAce G125 and G150 (all manufactured by YASUHARACHEMICAL Co., Ltd.).

[0216] Polyvinyl butyral resin is a copolymer of polyvinyl alcohol and butyral. The degree of butyralization, the content of hydroxyl and acetyl groups, and the degree of polymerization are determined according to the requirements of the ink composition. From the viewpoint of the viscosity of the ink composition and its solubility in solvents, a relatively low degree of polymerization is preferred for polyvinyl butyral resin. Polyvinyl butyral resins are commercially available, such as: S-LEC (registered trademark) BL-1, BL-2, BL-3, BL-S, BM-1, BM-2, BM-5, BM-S, BH-3, BH-S, BX-1, BX-2, BX-5, BX-10, BX-55 and BX-L (manufactured by Sekisui Chemicals Co., Ltd.); Denka Butyral #2000-L, #3000-1, #3000-2, #3000-4, #3000-K, #4000-1, #4000-2, #5000-A and #6000-C (manufactured by Denka Co., Ltd.).

[0217] Ketone resins are copolymers of ketone compounds and formaldehyde, preferably high molecular weight compounds with an average molecular weight of 3000 or more. Ketone resins can be chemically modified resins such as hydrogenated and / or end-group modified resins. Ketone resins are commercially available, for example, HILAC 111 and 222 (manufactured by Showa Denko Materials Co., Ltd.); K-90 (manufactured by Arakawa Chemical Co., Ltd.).

[0218] Rosin-modified maleic acid resins are particularly preferred among maleic acid resins. Rosin-modified maleic acid resins are polyesters of rosin, maleic acid, and polyols. Rosin-modified maleic acid resins are commercially available, for example, bainitic (registered trademark) P-720 and J-896 (manufactured by DIC Corporation); TESPOL (1101, 1103, 1104, 1105, 1150, 1151, 1152, 1155, 1158, and 1161) (manufactured by Showa Denko Materials Co., Ltd.).

[0219] The ink composition of the present invention is applicable to inkjet printers, preferably industrial inkjet printers, and particularly charge-controlled continuous inkjet (CIJ) printers. CIJ printer ink compositions sometimes contain charge modifiers to obtain the desired charge level. In the ink composition of the present invention, due to the high conductivity of the azo iron complex dye, a sufficient charge level is imparted to the ink composition, therefore, a charge modifier is generally not required. On the other hand, when a particularly high charge level is required, the ink composition may contain a charge modifier.

[0220] Examples of charge regulators include conductive salts such as salts of alkali metals like lithium, sodium, and potassium; salts of alkaline earth metals like magnesium and potassium; and ammonium and quaternary ammonium salts. Specifically, examples include perchlorates, thiocyanates, formates, acetates, sulfates, sulfonates, propionates, trifluoroacetates, trifluoro(trifluoro-methanesulfonate), hexafluorophosphates, hexafluoro-antimonates, tetrafluoroborates, picrates and carboxylates, tetrabutylammonium hexafluorophosphate, tetrabutylammonium bromide, and tetraphenylboron quaternary ammonium salts. Alkali metal halides and alkaline earth metal halides are also examples. Halides include fluorides, chlorides, bromides, and iodides. The charge regulator content in the ink composition is 0.1–10% by mass, preferably 0.1–5% by mass, and more preferably 0.3–3% by mass.

[0221] To ensure that the droplets are of the desired size when ejected from the nozzles of a CIJ printer, the ink composition for CIJ printers may contain a wetting agent. Wetting agents include surfactants, specifically anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.

[0222] Examples of anionic surfactants include fatty acid salts, alkyl sulfate salts, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl aryl ether sulfates, naphthalene sulfonic acid formaldehyde condensates, polyoxyethylene alkyl phosphate salts, glycerol borate fatty acid esters, and polyoxyethylene glycerol fatty acid esters.

[0223] Examples of cationic surfactants include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, and alkylimidazolium salts.

[0224] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, glycerol fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, fluorinated nonionic surfactants, and siloxane nonionic surfactants.

[0225] Examples of amphoteric surfactants include alkyl betaine, alkylamine oxide, and phosphatidylcholine.

[0226] The ink composition of the present invention may contain a pH adjuster to suppress changes in ink composition or decrease in storage stability, such as precipitation or sedimentation of dyes, etc. As a pH adjuster, it is not particularly limited as long as it is added for the above-mentioned purpose and can control the pH of the ink within the range of 7 to 8.

[0227] Specifically, examples of aliphatic substituted amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, and tripropylamine, and alkanolamines such as methanolamine, diethanolamine, triethanolamine, ethanolamine, diethanolamine, triethanolamine, propanolamine, dipropanolamine, and tripropanolamine are suitable as pH adjusters. From the viewpoint of inhibiting discoloration, alkanolamines such as triethanolamine are particularly preferred.

[0228] In addition to charge regulators and wetting agents, ink compositions may also contain additives to improve print quality, ink fixing, and the solubility stability of azo iron complex dyes, and to provide the required viscosity and surface tension. These additives include defoamers, chemical stabilizers, UV stabilizers, and stabilizers that inhibit salt corrosion; bactericides and fungicides; and biodegraders.

[0229] The method for manufacturing the ink composition is described. Azo iron complex dye, organic solvent, resin, and any necessary additives are placed in a sealed container and stirred. They are thus uniformly mixed and dissolved, and then filtered through a membrane filter. The mixed solution may also be heated if necessary.

[0230] The ink composition is used in the CIJ printer as follows: The ink composition stored in the ink can is drawn out by a pump and flows toward the printhead in the flow path. Droplets of the ink composition are ejected from a nozzle located at the end of the printhead. The droplets of the ink composition become charged by passing through charged electrodes and then continue to pass through deflection electrodes. The droplets of the ink composition are deflected into a predetermined arrangement in a manner that depicts the desired text or graphics, thereby reaching the printing medium at the front end of the deflection electrodes. Thus, text, etc., are depicted on the printing medium. For example, batch numbers, manufacturing dates, shelf-life dates, etc., are printed on the printing medium.

[0231] Printing media include, for example, invoices, cartons, product packaging, and plastic bottles. Examples of plastics used to form plastic bottles include polyolefins such as polyethylene and polypropylene; polyvinyl chloride; polyesters such as polyamide and PET; polycarbonate; polyacetal; polyacrylate; polyurethane; polyether; polystyrene; and polyimide.

[0232] The ink composition according to the present invention can be printed on glass such as soda-lime glass and borosilicate glass, the aforementioned plastics, and metals such as aluminum, iron, tin, and copper using a CIJ printer. When the printing medium is metal, good printing can be achieved by performing a pretreatment that roughens the metal surface by sandblasting or acid pickling.

[0233] The ink composition is also suitable as an ink for writing instruments. When used as an ink for writing instruments, specifically as an ink for marking pens, the ink composition contains 5-10% by mass of an azo iron complex dye; when used as an ink for ballpoint pens, it contains 15-25% by mass.

[0234]

Example

[0235] The present invention will be described in more detail below with examples, but the invention is not limited to these examples. In these examples, % represents mass%.

[0236] (Preparation Example 1: Synthesis of diazo dye D-1)

[0237] Add 118.0 g (1.0 mol) of p-aminobenzonitrile and 339 g of 35% hydrochloric acid to 592.0 g of ion-exchanged water, cool to -3 °C in an ice bath, and gradually add 178 g of 40% sodium nitrite aqueous solution to carry out a diazotization reaction to obtain a diazonium salt solution.

[0238] In another beaker, 123.0 g (1.0 mol) of 2-amino-p-cresol and 104.0 g of 35% hydrochloric acid were added to 412 g of deion-exchanged water and dissolved. 4 g of 1-butanol and 140 g of ice were added, and the mixture was cooled to 2°C. The previously prepared diazonium salt solution was then slowly added dropwise. The pH was adjusted to 4.9 with a 20% sodium hydroxide aqueous solution, and the precipitate was filtered under reduced pressure. The precipitate was washed with deion-exchanged water to obtain a wet filter cake of 664 g of the monoazo compound represented by the following chemical formula (18).

[0239]

Chemistry 27

[0240]

[0241] 304 g (0.42 mol) of the previously obtained monoazo compound wet filter cake was added to 402 g of ion-exchanged water and stirred to disperse. 49 g of 48% potassium hydroxide aqueous solution was gradually added. After stirring for 30 minutes, 126 g of ion-exchanged water and 84 g of ice were added, and stirring was continued for another 30 minutes. After stirring was complete, 75 g of 40% sodium nitrite aqueous solution was added, and stirring was continued for 5 minutes. Then, 153 g of 35% hydrochloric acid was added dropwise using a dropping funnel. After the addition, stirring was continued for approximately 1 hour to obtain a diazonium salt solution.

[0242] In another beaker, 88 g (0.40 mol) of N,N-dibutylaminophenol, 133 g of 48% potassium hydroxide aqueous solution, and 1332 g of methanol were dissolved by stirring under ice-cold conditions. The previously obtained diazonium salt solution was added dropwise, and the mixture was stirred for 12 hours. The precipitate was filtered under reduced pressure and washed with deionized water to obtain 409 g of wet filter cake. This was dried at 80 °C to obtain 163.6 g of diazo dye D-1 represented by the following chemical formula (19).

[0243]

Chemistry 28

[0244]

[0245] (Preparation Example 2: Synthesis of diazo dye D-2)

[0246] 107.5 g of p-nitroaniline (0.78 mol) and 290 g of 35% hydrochloric acid were added to 200.0 g of ion-exchange water, and the mixture was heated to 65 °C while stirring. After stirring for 1 hour, the mixture was cooled to -3 °C in an ice bath. 138.5 g of 40% sodium nitrite aqueous solution was gradually added to the mixture to carry out a diazotization reaction, yielding a diazonium salt solution.

[0247] In another beaker, 96.0 g (0.78 mol) of 2-amino-p-cresol and 81.0 g of 35% hydrochloric acid were dissolved in 500 g of deion-exchanged water. Then, 4 g of 1-butanol and 140 g of ice were added, and the mixture was cooled to 2°C in an ice bath. The previously prepared diazonium salt solution was gradually added dropwise. The pH was adjusted to 4.8 with a 20% sodium hydroxide aqueous solution, and the precipitate was filtered under reduced pressure. The precipitate was washed with deion-exchanged water to obtain a wet filter cake of 163.1 g of the monoazo compound represented by the following chemical formula (20).

[0248]

Chemistry 29

[0249]

[0250] 162 g (0.60 mol) of the previously obtained wet filter cake and 147.5 g of 35% hydrochloric acid were added to 1643 g of N,N-dimethylformamide, and the mixture was heated to 60 °C while stirring to dissolve it. After visually confirming that there were no lumps, the mixture was cooled to 20 °C in an ice bath. 105.7 g of 40% sodium nitrite aqueous solution was gradually added, and the mixture was stirred at room temperature for 2 hours to obtain a diazonium salt solution.

[0251] In another beaker, 131.7 g of N,N-dibutylaminophenol (0.60 mol) and 133 g of 48% potassium hydroxide aqueous solution were added to 1200 g of methanol and stirred under ice-cold conditions to dissolve. The previously obtained diazonium salt solution was added dropwise, and the mixture was stirred for 12 hours. The precipitate was filtered under reduced pressure and washed with deionized water to obtain 409 g of wet filter cake. This was dried at 80 °C to obtain 75.2 g of the diazo dye D-2 as shown in chemical formula (21).

[0252]

Transformation 30

[0253]

[0254] (Preparation Example 3: Synthesis of diazo dye D-3)

[0255] 172 g of p-aminobenzenesulfonamide (1.00 mol) and 271 g of 35% hydrochloric acid were added to 600.0 g of ion-exchange water and cooled to -3°C in an ice bath. 179.3 g of 40% sodium nitrite aqueous solution was gradually added. Then, 2.4 g of urea was added to initiate a diazotization reaction, yielding a diazonium salt solution.

[0256] In another beaker, 123.4 g (1.00 mol) of 2-amino-p-cresol and 125.0 g of 35% hydrochloric acid were dissolved in 440 g of deion-exchanged water. 4 g of 1-butanol and 140 g of ice were added, and the mixture was cooled to 2°C in an ice bath. The previously prepared diazonium solution was then slowly added dropwise. The pH was adjusted to 4.8 with a 20% sodium hydroxide aqueous solution, and the precipitate was filtered under reduced pressure. The precipitate was washed with deion-exchanged water to obtain a wet filter cake of 719.5 g of the monoazo compound represented by the following chemical formula (22).

[0257]

Chemistry 31

[0258]

[0259] 700 g (0.90 mol) of the pre-obtained monoazo compound wet filter cake was dispersed in 700 g of ion-exchanged water, and then 82.7 g of 48% sodium hydroxide aqueous solution was gradually added and stirred for 1 hour. 700 g of ice was added in an ice bath, and after cooling to 1°C, 162.0 g of 40% sodium nitrite aqueous solution was gradually added. After stirring for a period of time, 300 g of ice was added, and then 287.0 g of 35% hydrochloric acid was gradually added. The mixture was stirred at room temperature for 2 hours to obtain a diazonium salt solution.

[0260] In another beaker, 193.2 g (0.88 mol) of N,N-dibutylaminophenol and 217.5 g of 48% sodium hydroxide aqueous solution were added to 690 g of methanol and stirred under ice-cold conditions to dissolve. The previously obtained diazonium salt solution was added dropwise, and the mixture was stirred for 12 hours. The pH was adjusted to 4.0 using 35% hydrochloric acid, and the temperature was raised to 35°C and stirred for 1 hour. The precipitate was filtered under reduced pressure and washed with deionized water to obtain 441.1 g of wet filter cake. This was dried at 80°C to obtain 175.2 g of the diazo pigment D-3 as shown in the following chemical formula (23).

[0261]

Chemistry 32

[0262]

[0263] (Preparation Example 4: Synthesis of diazo dye D-4)

[0264] 67.6 g (0.50 mol) of 4-acetaminophen and 114.6 g of 35% hydrochloric acid were added to 688.0 g of ion-exchanged water and cooled to -3°C in an ice bath. 90.6 g of 40% sodium nitrite aqueous solution was gradually added to initiate a diazotization reaction. After stirring for 1 hour, 1.9 g of thiourea was added to obtain a diazonium salt solution.

[0265] In another beaker, 61.6 g (0.50 mol) of 2-amino-p-cresol and 52.1 g of 35% hydrochloric acid were added to 1111 g of methanol and dissolved. After cooling to 5 °C in an ice bath, the previously prepared diazonium solution was gradually added dropwise. The precipitate was filtered under reduced pressure, washed with deionized water, and dried at 80 °C to give 56.3 g of the monoazo compound represented by the following chemical formula (24).

[0266]

Transformation 33

[0267]

[0268] 56.0 g of the previously obtained monoazo compound (0.18 mol) and 45.4 g of 35% hydrochloric acid were added to 415 g of N,N-dimethylformamide solution. 84 g of ice was added in an ice bath, and the mixture was cooled to 2°C. 32.6 g of 40% sodium nitrite aqueous solution was slowly added, and the mixture was stirred for 1 hour. 1.8 g of aminosulfonic acid was then added to obtain a diazonium salt solution.

[0269] In another beaker, 40.6 g (0.18 mol) of N,N-dibutylaminophenol and 79.1 g of 20% sodium hydroxide aqueous solution were added to 612.1 g of methanol and stirred under ice-cold conditions until dissolved. The previously obtained diazonium salt solution was added dropwise, and the mixture was stirred for 3 hours. The precipitate was filtered under reduced pressure, washed with methanol, and dried at 80 °C to obtain 15.9 g of the diazo dye D-4 as shown in chemical formula (25).

[0270]

Transformation 34

[0271]

[0272] (Preparation Example 5: Synthesis of Monoazo Pigment M-1)

[0273] 7.5 g (0.05 mol) of 5-nitro-2-aminophenol and 13.6 g of 35% hydrochloric acid were added to 50.0 g of isopropanol to dissolve them. Then, 8.0 g of 40% sodium nitrite aqueous solution was gradually added in an ice bath to diazotize and obtain a diazonium salt solution.

[0274] Add 200g of water to another beaker, then add 26.1g of a 20% sodium hydroxide aqueous solution, followed by 6.6g of 2-naphthol to disperse it. Add the previously prepared diazonium salt dropwise to the dispersion and allow it to react for 3 hours. Then, filter and wash with water the monoazo compound that precipitates after adjusting the pH to 2.8 to obtain 82.5g of a wet filter cake of monoazo compound M-1 as shown in chemical formula (26) below.

[0275]

Chemistry 35

[0276]

[0277] (Preparation Example 6: Synthesis of Monoazo Pigment M-2)

[0278] 7.5 g (0.05 mol) of 4-nitro-2-aminophenol and 13.6 g of 35% hydrochloric acid were added to 50.0 g of isopropanol to dissolve them. Under ice bath conditions, 8.0 g of 40% sodium nitrite aqueous solution was gradually added to carry out diazotization and obtain a diazonium salt solution.

[0279] Add 200g of water to another beaker, then add 26.1g of a 20% sodium hydroxide aqueous solution, followed by 6.6g (0.05mol) of 2-naphthol to disperse it. Add the previously prepared diazonium salt dropwise to the dispersion and react for 3 hours. Then, filter and wash with water the monoazo compound that precipitated after adjusting the pH to 2.8 to obtain 81.8g of wet filter cake of monoazo M-2 as shown in the following chemical formula (27).

[0280]

Transformation 36

[0281]

[0282] (Preparation Example 7: Synthesis of Monoazo Pigment M-3)

[0283] 7.0 g (0.05 mol) of 4-chloro-2-aminophenol and 13.6 g of 35% hydrochloric acid were dissolved in 50.0 g of isopropanol. Under ice bath conditions, 8.0 g of 40% sodium nitrite aqueous solution was gradually added to diazotize and obtain a diazonium salt solution.

[0284] Add 200g of water to another beaker, then add 26.1g of a 20% sodium hydroxide aqueous solution, followed by 6.6g (0.05mol) of 2-naphthol to disperse it. Add the previously prepared diazonium salt dropwise to the dispersion and react for 3 hours. Then, filter and wash with water the monoazo compound that precipitated after adjusting the pH to 2.8 to obtain 80.1g of a wet filter cake of monoazo compound M-3 as shown in the following chemical formula (28).

[0285]

Chemistry 37

[0286]

[0287] (Preparation Example 8: Synthesis of Monoazo Pigment M-4)

[0288] 7.0 g (0.05 mol) of 4-chloro-2-aminophenol and 13.6 g of 35% hydrochloric acid were added to 50.0 g of isopropanol to dissolve them. Under ice bath conditions, 8.0 g of 40% sodium nitrite aqueous solution was gradually added to diazotize and obtain a diazonium salt solution.

[0289] Add 200g of water to another beaker, then add 26.1g of a 20% sodium hydroxide aqueous solution, followed by 6.6g (0.05mol) of 2-naphthol, and disperse the solution. Add the previously prepared diazonium salt dropwise to the dispersion and react for 3 hours. Then, filter and wash with water the monoazo compound that precipitates after adjusting the pH to 2.8 to obtain 80.1g of a wet filter cake of monoazo compound M-3 as shown in the following chemical formula (29).

[0290]

Transformation 38

[0291]

[0292] (Preparation Example 9: Synthesis of Monoazo Pigment M-5)

[0293] 34.0 g (0.24 mol) of 4-chloro-2-aminophenol and 82.2 g of 35% hydrochloric acid were added to 182.0 g of isopropanol to dissolve them. Under ice bath conditions, 48.9 g of 40% sodium nitrite aqueous solution was gradually added to carry out diazotization and obtain a diazonium salt solution.

[0294] 182 g of isopropanol was added to another beaker, followed by 107.2 g of a 20% sodium hydroxide aqueous solution, and then 60.7 g (0.24 mol) of 6-tert-octyl-2-naphthol. The solution was dissolved, and the previously prepared diazonium salt was added dropwise. The reaction was allowed to proceed for 2 hours. The precipitate was then filtered, washed with water, and dried to obtain 93.5 g of the monoazo dye M-5 as shown in chemical formula (30).

[0295]

Chemistry 39

[0296]

[0297] (Example 1: Synthesis of azo iron complex dye A-1)

[0298] 5.3 g (0.011 mol) of diazo dye D-1 obtained in Preparation Example 1 and 22.1 g (40% water content, 0.043 mol) of wet filter cake of monoazo dye M-1 obtained in Preparation Example 5 were added to 120 g of N,N-dimethylformamide solution and stirred at 55 °C for 1 hour (diazo dye: monoazo dye = 2:8 mol). 12.4 g (0.013 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 120 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 9.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 10.0. Then, 103.6 g of 5% tert-alkyl (C) ethers were gradually added to the reaction solution. 12 ~C 14 A primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) aqueous solution was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried to obtain 23.1 g of azo iron complex dye A-1 containing a diazo-monoazo iron complex (DM body) represented by the following chemical formula (31DM), a monoazo-monoazo iron complex (MM body) represented by the following chemical formula (31MM), and a diazo-diazo iron complex (DD body) represented by the following chemical formula (31DD).

[0299]

Chemistry 40

[0300]

[0301]

Chemistry 41

[0302]

[0303]

Chemistry 42

[0304]

[0305] (Measurement of absorbance)

[0306] A solution was prepared such that the concentration of azo iron complex dye A-1 in methyl ethyl ketone was 10 mg / 1000 ml (10 ppm). The absorbance of this solution was measured using a UV-Vis spectrophotometer (Shimadzu Corporation; trade name UV-1700). The visible absorption spectrum of azo iron complex dye A-1 is shown below. Figure 1 As shown, a solution of azo iron complex dye A-1 adjusted to a concentration of 5% exhibits a fully black color.

[0307] (Measurement of electrical conductivity)

[0308] A 6% methyl ethyl ketone solution of azo iron complex dye A-1 was prepared and measured using a conductivity meter (Eutech Instruments; trade name CyberScan CON100). The result was a conductivity K of 1530 μS / cm. Subsequently, a 6% methyl ethyl ketone solution of azo iron complex dye A-1 was prepared and measured using a conductivity meter (Knick; trade name Conducell 4USF-PG120). The result was a conductivity K of 1530 μS / cm.

[0309] (Determination of alkali metal ion content)

[0310] The content of alkali metal ions (Na ions) in azo iron complex dyes was determined using an atomic absorption spectrophotometer (manufactured by Varian technology Japan Limited; trade name SpectrAA-220FS). The results showed that the content of alkali metal ions was less than 1000 ppm.

[0311] Example 2: Synthesis of azo iron complex dye A-2

[0312] 9.69 g (0.020 mol) of the diazo dye D-1 obtained in Preparation Example 1 and 10.6 g (42% water content, 0.020 mol) of the wet filter cake of the monoazo dye M-2 obtained in Preparation Example 6 were added to 100 g of N,N-dimethylformamide solution and stirred at 55 °C for 1 hour (diazo dye: monoazo dye = 5:5 mol). 9.5 g (0.010 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 120 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 9.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 10.1. Then, 80.6 g of 5% tert-alkyl (C) esters were gradually added to the reaction solution. 12 ~C 14 A primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) aqueous solution was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried to obtain 15.6 g of an azo iron complex dye A-2 containing the DM body represented by the following chemical formula (32DM), the MM body represented by the following chemical formula (32MM), and the DD body represented by the following chemical formula (32DD).

[0313]

Chemistry 43

[0314]

[0315]

Chemistry 44

[0316]

[0317]

Chemistry 45

[0318]

[0319] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye A-2 were determined in the same manner as those of azo iron complex dye A-1. The visible absorption spectrum of azo iron complex dye A-2 is shown below. Figure 2 As shown, a solution of azo iron complex dye A-2 adjusted to a concentration of 5% exhibits a fully black color. Furthermore, the conductivity K of azo iron complex dye A-2 is 908 μS / cm, and the alkali metal ion content is below 1000 ppm.

[0320] (Example 3: Synthesis of azo iron complex dye A-3)

[0321] 5.33 g (0.011 mol) of diazo dye D-1 obtained in Preparation Example 1 and 21.9 g (40% water content, 0.044 mol) of wet filter cake of monoazo dye M-3 obtained in Preparation Example 7 were added to 100 g of N,N-dimethylformamide solution and stirred at 55 °C for 1 hour (diazo dye: monoazo dye = 2:8 mol). 12.9 g (0.013 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 120 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 9.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 10.2. Then, 103.0 g of 5% tert-alkyl (C) ethers were gradually added to the reaction solution. 12 ~C 14 A primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) aqueous solution was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried to obtain 17.8 g of an azo iron complex dye A-3 containing the DM body represented by the following chemical formula (33DM), the MM body represented by the following chemical formula (33MM), and the DD body represented by the following chemical formula (33DD).

[0322]

Chemistry 46

[0323]

[0324]

Chemistry 47

[0325]

[0326]

Chemistry 48

[0327]

[0328] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye A-3 were determined in the same manner as those of azo iron complex dye A-1. The visible absorption spectrum of azo iron complex dye A-3 is shown below. Figure 3 As shown, a solution of azo iron complex dye A-3 adjusted to a concentration of 5% exhibits a fully black color. Furthermore, the conductivity K of azo iron complex dye A-3 is 1260 μS / cm, and the alkali metal ion content is below 1000 ppm.

[0329] Example 4: Synthesis of azo iron complex dye A-4

[0330] 5.55 g (0.011 mol) of the diazo dye D-2 obtained in Preparation Example 2 and 21.9 g (40% water content, 0.043 mol) of the wet filter cake of the monoazo ligand M-2 obtained in Preparation Example 6 were added to 100 g of N,N-dimethylformamide solution and stirred at 55 °C for 1 hour (diazo dye: monoazo dye = 2:8 mol). 12.4 g (0.013 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 120 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 9.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 10.1. Then, 102.8 g of 5% tertiary alkyl (C) ether was gradually added to the reaction solution. 12 ~C 14 A primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) aqueous solution was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried to obtain 16.5 g of an azo iron complex dye A-4 containing the DM body represented by the following chemical formula (34DM), the MM body represented by the following chemical formula (34MM), and the DD body represented by the following chemical formula (34DD).

[0331]

Chemistry 49

[0332]

[0333] [Transformation 50]

[0334]

[0335]

Chemistry 51

[0336]

[0337] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye A-4 were determined in the same manner as those of azo iron complex dye A-1. The visible absorption spectrum of azo iron complex dye A-4 is shown below. Figure 4As shown, a solution of azo iron complex dye A-4 adjusted to a concentration of 5% exhibits a fully black color. Furthermore, the conductivity K of azo iron complex dye A-4 is 1275 μS / cm, and the alkali metal ion content is below 1000 ppm.

[0338] (Example 5: Synthesis of azo iron complex dye A-5)

[0339] 12.9 g (0.024 mol) of the diazo dye D-3 obtained in Preparation Example 3 and 18.7 g (40% water content, 0.036 mol) of the wet filter cake of the monoazo dye M-2 obtained in Preparation Example 6 were added to 120 g of N,N-dimethylformamide solution and stirred at 55 °C for 1 hour (diazo dye: monoazo dye = 4:6 mol). 15.0 g (0.015 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 120 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 9.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 9.9. Then, 125.3 g of 5% tert-alkyl (C) ethers were gradually added to the reaction solution. 12 ~C 14 A primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) aqueous solution was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried to obtain 15.9 g of an azo iron complex dye A-5 containing the DM body represented by the following chemical formula (35DM), the MM body represented by the following chemical formula (35MM), and the DD body represented by the following chemical formula (35DD).

[0340]

Chemistry 52

[0341]

[0342]

Chemistry 53

[0343]

[0344]

Chemistry 54

[0345]

[0346] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye A-5 were determined using the same method as for azo iron complex dye A-1. The visible absorption spectrum of azo iron complex dye A-5 is shown below. Figure 5 As shown, a solution of azo iron complex dye A-5 adjusted to a concentration of 5% exhibits a fully black color. Furthermore, the conductivity K of azo iron complex dye A-5 is 920 μS / cm, and the alkali metal ion content is below 1000 ppm.

[0347] (Example 6: Synthesis of azo iron complex dye A-6)

[0348] 5.3 g (0.011 mol) of diazo dye D-1 obtained in Preparation Example 1, 11.2 g (40% water content, 0.022 mol) of wet filter cake of monoazo dye M-1 obtained in Preparation Example 5, and 11.6 g (42% water content, 0.022 mol) of wet filter cake of monoazo dye M-2 obtained in Preparation Example 6 were added to 120 g of N,N-dimethylformamide solution and stirred at 55 °C for 1 hour (diazo dye: monoazo dye 1: monoazo dye 2 = 2:4:4 mol). 12.4 g (0.013 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 120 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 9.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 10.1. 100.4 g of 5% tertiary alkyl (C) was gradually added to the reaction solution. 12 ~C 14 A primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) aqueous solution was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried to obtain 14.4 g of an azo iron complex dye A-6 containing the DM body represented by the following chemical formula (36DM), the MM body represented by the following chemical formula (36MM), and the DD body represented by the following chemical formula (36DD).

[0349]

Transformation 55

[0350]

[0351]

Transformation 56

[0352]

[0353]

Chemistry 57

[0354]

[0355] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye A-6 were determined using the same method as for azo iron complex dye A-1. The visible absorption spectrum of azo iron complex dye A-6 is shown below. Figure 6 As shown in the figure, a solution of azo iron complex dye A-6 adjusted to a concentration of 5% produces a fully black color. Furthermore, the conductivity K of azo iron complex dye A-6 is 1450 μS / cm, and the alkali metal ion content is below 1000 ppm.

[0356] (Example 7: Synthesis of azo iron complex dye A-7)

[0357] 12.9 g (0.024 mol) of diazo dye D-3 obtained in Preparation Example 5, 32.0 g (40% water content, 0.056 mol) of wet filter cake of monoazo dye M-4 obtained in Preparation Example 8, 200 g of deionized water, 12 g of n-butanol, and 48 g of 20% sodium hydroxide aqueous solution were added and stirred at 70 °C for 30 minutes (diazo dye: monoazo dye = 3:7 mol). 20.0 g (0.021 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 90 °C and stirred for 3 hours. After the reaction was complete, the mixture was cooled to room temperature, and 191.3 g of 5% tertiary alkyl (C) was gradually added to the reaction solution. 12 ~C 14 A primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) aqueous solution was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried to obtain 40.2 g of an azo iron complex dye A-7 containing the DM body represented by the following chemical formula (37DM), the MM body represented by the following chemical formula (37MM), and the DD body represented by the following chemical formula (37DD).

[0358]

Transformation 58

[0359]

[0360]

Chemistry 59

[0361]

[0362]

Transformation 60

[0363]

[0364] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye A-7 were determined using the same method as for azo iron complex dye A-1. The visible absorption spectrum of azo iron complex dye A-7 is shown below. Figure 7 As shown, a solution of azo iron complex dye A-7 adjusted to a concentration of 5% exhibits a fully black color. Furthermore, the conductivity K of azo iron complex dye A-7 is 826 μS / cm, and the alkali metal ion content is below 1000 ppm.

[0365] (Comparative Example 1: Synthesis of azo iron complex dye B-1)

[0366] 42.5 g of wet filter cake (42% water content, 0.080 mol) of the monoazo dye M-2 obtained in Preparation Example 6, 120 g of deionized water, and 5.7 g of n-butanol were added to 12.5 g of 20% sodium hydroxide aqueous solution and stirred at 90 °C for 1 hour (diazo dye: monoazo dye = 0:10 mol). 40.7 g (0.042 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 90 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 9.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 10.1. Then, 100.4 g of 5% tert-alkyl (C) groups were gradually added to the reaction solution. 12 ~C 14 An aqueous solution of primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) was heated and stirred at 40°C for 1 hour. The precipitate was then filtered, washed with water, and dried. The result, as shown in the following chemical formula (38MM), yielded 27.4 g of azo-iron complex dye B-1, consisting solely of a monoazo-monoazo iron complex.

[0367]

Chemistry 61

[0368]

[0369] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye B-1 were determined using the same method as for azo iron complex dye A-1. A 5% solution of azo iron complex dye B-1 turned a brownish-red color. Furthermore, the conductivity K of azo iron complex dye B-1 was 1450 μS / cm, and the alkali metal ion content was below 1000 ppm.

[0370] (Comparative Example 2: Synthesis of azo iron complex dye B-2)

[0371] 21.9 g of wet filter cake (42% water content, 0.026 mol) of diazo dye D-1 obtained in Preparation Example 1 and 2.9 g of urea were added to 100 g of N,N-dimethylformamide solution and stirred at 50 °C for 1 hour (diazo dye: monoazo dye = 10:0 mol). 6.33 g (0.007 mol) of 41% ferric sulfate aqueous solution was added dropwise. After the addition was complete, the temperature was raised to 120 °C and stirred for 3 hours. After the reaction was complete, the solution was cooled to room temperature, and 5.0 g of 20% sodium hydroxide aqueous solution was added to adjust the pH to 10.9. 80.1 g of 5% tert-alkyl (C) ethers were then gradually added to the reaction solution. 12 ~C 14An aqueous solution of primary amine (manufactured by Dow Chemical Company; trade name PRIMENE 81-R) was heated and stirred at 35°C for 2 hours. The precipitate was then filtered, washed with water, and dried. As a result, 9.41 g of an azo-iron complex dye B-2, consisting solely of a diazo-diazo-iron complex, was obtained, as shown in the following chemical formula (39DD).

[0372]

Transformation 62

[0373]

[0374] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye B-2 were determined in the same manner as those of azo iron complex dye A-1. When dissolved at a concentration of 5%, azo iron complex dye B-2 showed a fully black color. However, azo iron complex dye B-2 lacked solubility stability; precipitation was confirmed after standing overnight (8 hours). Furthermore, the conductivity K of freshly dissolved azo iron complex dye B-2 was 165 μS / cm, and the alkali metal ion content was below 1000 ppm.

[0375] (Comparative Example 3: Azo iron complex dye B-3)

[0376] Five parts by mass of azo iron complex dye B-1 obtained in Comparative Example 1 and five parts by mass of azo iron complex dye B-2 obtained in Comparative Example 2 were pulverized and mixed using an experimental micro mixer (manufactured by As One Co., Ltd.) to obtain 9.9 g of azo iron complex dye B-3 as a mixture of azo iron complex dye B-1 and azo iron complex dye B-2.

[0377] The absorbance, conductivity, and alkali metal ion content of azo iron complex dye B-3 were determined using the same method as for azo iron complex dye A-1. A 5% solution of azo iron complex dye B-3 exhibited a reddish-black color. Furthermore, the conductivity K of azo iron complex dye B-1 was 979 μS / cm, and the alkali metal ion content was below 1000 ppm.

[0378] (Comparison of visible absorption spectra)

[0379] The visible absorption spectra of the azo iron complex dye A-1 obtained in Example 1 and the azo iron complex dyes B-1 to B-3 obtained in Comparative Examples 1 to 3 are overlaid and shown. Figure 8 The visible absorption spectrum of the azo iron complex dye B-1 in the 400nm–550nm range is stronger than that of the azo iron complex dye A-1. This indicates that the azo iron complex dye B-1 exhibits a strong red hue.

[0380] The visible absorption spectrum of the azo iron complex dye B-2 exhibits particularly strong absorption in the long wavelength region above 550 nm. This indicates that the azo iron complex dye B-2 displays a strong blue hue.

[0381] The visible absorption spectrum of the azo iron complex dye B-3 shows approximately the same visible absorption spectrum as that of the azo iron complex dye A-1. On the other hand, as mentioned above, the azo iron complex dye A-1 is practically a solid black, while the azo iron complex dye B-3 is a reddish black. A detailed comparison of their spectra reveals that in the visible absorption spectrum from 400 nm to 550 nm, the azo iron complex dye B-3 has a higher absorption than the azo iron complex dye A-1, while the absorbance in the 600 nm to 650 nm range is equal. This indicates that the MD component, which is only present in the azo iron complex dye A-1, contributes significantly to the blackness.

[0382] (Confirm the composition of the azo iron complex dye)

[0383] The azo iron complex dyes A-1 to A-7 of the present invention contain at least three azo iron complexes: DM, DD, and MM. The relative proportions (molar ratios) of these azo iron complex dyes can be determined by the peak area ratios in the chromatograms obtained by high-performance liquid chromatography (HPLC; manufactured by Shimadzu Corporation, Prominence) at a specific wavelength. For the azo iron complex dyes A-1 to C-6 obtained in Examples 1 to 7 and the azo iron complex dye B-1 obtained in Comparative Examples 1 to 3 of Comparative Example 1, 1 mg of each azo iron complex dye was dissolved in 10 ml of dimethylformamide solution, and the determination was performed under the following conditions. The results are shown in Table 4.

[0384] Rapid liquid chromatography:

[0385] Column: L-COLUMN ODS 24.6×250mm, 5μm

[0386] Column temperature: 40℃

[0387] Moving phase:

[0388] Solution A: Tetrahydrofuran (HPLC grade, manufactured by Fujifilm and Kojun Chemical Co., Ltd.) / Acetonitrile (manufactured by the same company) = 3 / 2

[0389] Solution B: Ultrapure water / 10mM tetraethylammonium (Waters Corporation) = 500 / 7.5

[0390] Gradient: Solution A / Solution B 50:50 → 70:30

[0391] Measurement wavelength: UV at 254nm

[0392] Table 4

[0393] Table 4

[0394]

[0395] (Solubility evaluation)

[0396] The azo iron complex dyes A-1 to A-7 obtained in Examples 1 to 7 and the azo iron complex dyes B-1 to B-3 obtained in Comparative Examples 1 to 3 were respectively added to methyl ethyl ketone (MEK) and ethanol to prepare azo iron complex dye solutions at concentrations of 5%, 10%, 15%, and 20%, and then ultrasonically dispersed for 10 minutes. The azo iron complex dye solutions were then filtered under reduced pressure using a membrane filter (1 μm pore size, PTFE), and the concentration at which no undissolved matter was observed on the membrane filter was taken as the maximum concentration of the azo iron complex dye. Furthermore, the hue of a 5% MEK solution of the azo iron complex dye was visually observed. The results are shown in Table 5.

[0397] Table 5

[0398] Table 5

[0399]

[0400] By applying this invention, in the examples where azo iron complex dyes must contain a diazo-monoazo iron complex, the 5% methyl ethyl ketone (MEK) solution exhibits a practical black hue. Specifically, azo iron complex dyes A-1, A-2, and A-6, with a cyano group on the diazo ligand and a nitro group on the monoazo ligand, respectively, show high solubility in both MEK and ethanol. Azo iron complex dyes A-5, with a sulfonamide group on the diazo ligand and a nitro group on the monoazo ligand, and A-7, with both a sulfonamide group on the diazo ligand and the monoazo ligand, respectively, exhibit slightly lower conductivity; furthermore, the methyl ethyl ketone solution, with a slightly reddish hue, also shows very high solubility in ethanol. Azo iron complex dye A-3, with a chlorine substituent on the monoazo ligand, shows low solubility in ethanol but high solubility in MEK exceeding 10% (over 6% of the practical concentration).

[0401] In comparative examples where the present invention was not applied, the azo iron complex dye B-1, composed solely of monoazo-monazo iron complexes, exhibited good solubility but presented a reddish-brown hue rather than a black one. The azo iron complex dye B-2, composed solely of diazo-diazo iron complexes, presented a usable black color but showed low solubility in both methyl ethyl ketone (MEK) and ethanol. Furthermore, it lacked solubility stability in ethanol; precipitation was observed when the ethanol solution of azo iron complex dye B-2 was allowed to stand for approximately 10 minutes. The methyl ethyl ketone solution of azo iron complex dye B-3, a mixture of azo iron complex dye B-1 (composed solely of monoazo-monazo iron complexes) and azo iron complex dye B-2 (composed solely of diazo-diazo iron complexes), presented only a reddish-black color, and precipitation was observed when this ethanol solution was allowed to stand for approximately 10 minutes.

[0402] (Ink Example 1)

[0403] Six parts by weight of cellulose resin, one part by weight of lithium nitrate, and three parts by weight of azo iron complex dye A-1 were added to 70 parts by weight of methyl ethyl ketone, 10 parts by weight of ethanol, and 10 parts by weight of isopropanol and stirred until dissolved. The mixture was then filtered through a 1.0 μm filter to obtain the ink composition of Example 1. This ink composition was filled into an ink cartridge and printed using an inkjet printer, resulting in black characters. The characters were deep black without streaks. Therefore, the ink composition of Example 1 was evaluated as having good character density and ink ejection stability.

[0404] (Ink Example 2)

[0405] Except for using azo iron complex dye A-2 instead of azo iron complex dye A-1, the same procedure as in Ink Example 1 was followed to obtain the ink composition of Ink Example 2. Using this ink composition, the same procedure as in Ink Example 1 was followed to obtain black printed text. The printed text had no streaks and was a deep black. Therefore, the ink composition of Ink Example 2 was evaluated as having good printing density and ink ejection stability.

[0406] (Ink Example 3)

[0407] Except for using azo iron complex dye A-5 instead of azo iron complex dye A-1, the same procedure as in Ink Example 1 was followed to obtain the ink composition of Ink Example 3. Using this ink composition, the same procedure as in Ink Example 1 was followed to obtain black printed text. The printed text had no streaks and was a deep black. Therefore, the ink composition of Ink Example 3 was evaluated as having good printing density and ink ejection stability.

[0408] (Ink Example 4)

[0409] Except for replacing azo iron complex dye A-1 with azo iron complex dye A-6 and adding 0.5 parts by weight of triethanolamine as a pH adjuster, the ink composition of Ink Example 4 was obtained by operating in the same manner as in Ink Example 1. Using this ink composition, the same procedure as in Ink Example 1 was followed to obtain black printed text. The printed text was deep black without streaks. Therefore, the ink composition of Ink Example 4 was evaluated as having good printing density and ink ejection stability.

[0410] (Ink Comparison Example 1)

[0411] Except for using azo iron complex dye B-1 instead of azo iron complex dye A-1, the same procedure was followed as in Ink Example 1 to obtain the ink composition of Ink Comparative Example 1. Using this ink composition, the same procedure as in Ink Example 1 was followed and printed on a printing medium to obtain light brown printed text without concealment.

[0412] (Ink Comparison Example 2)

[0413] Except that azo iron complex dye B-2 was used instead of azo iron complex dye A-1, the same procedure as in Ink Example 1 was followed to obtain the ink composition of Comparative Ink Example 2. However, when this ink composition was left to stand for about 10 minutes, precipitates were formed. These were removed by filtration. Using the ink composition, the same procedure as in Ink Example 1 was followed and the ink was printed on a printing medium to obtain light black printed characters.

[0414] (Ink Comparison Example 3)

[0415] Except for using azo iron complex dye B-3 instead of azo iron complex dye A-1, the same procedure was followed as in Ink Example 1 to obtain the ink composition of Comparative Ink Example 3. Using this ink composition, the same procedure as in Ink Example 1 was followed and printed on a printing medium to obtain light brown printed text without opacity.

[0416] [Industry Applicability]

[0417] The azo iron complex dye and ink compositions containing the azo iron complex dye of the present invention are used as inks for inkjet printers, writing instruments, and recorders. The method for manufacturing the azo iron complex dye of the present invention is used to manufacture the aforementioned azo iron complex.

Claims

1. An azo iron complex dye, characterized in that, Contains a diazo-monadizo iron complex represented by the following chemical formula (1), 【Chemistry 1】 In chemical formula (1), R 1 and R 2 Each of the following is an independent straight-chain or branched alkyl group having 3-10 carbon atoms, R 3 R is an electron-withdrawing group. 4 R is a straight-chain or branched alkyl group having 1-5 carbon atoms, or a straight-chain or branched alkoxy group having 1-5 carbon atoms. 5 R is a nitro group, a sulfonamide group, or a halogen atom. 6 R is a hydrogen atom, a straight-chain or branched alkyl group, a nitro group, or a halogen atom with 1-8 carbon atoms. 7 A is a straight-chain or branched alkyl group with 3-12 carbon atoms or hydrogen atoms. + It is a monovalent cation.

2. The azo iron complex dye as described in claim 1, characterized in that, The R 3 The para-position relative to the azo group, which is attached to the same aromatic ring, is an electron-withdrawing group selected from cyano, nitro, acetyl, sulfonamide, and halogen atoms.

3. The azo iron complex dye as described in claim 1, characterized in that, It also contains a monoazo-monazo iron complex represented by the following chemical formula (2), 【Chemistry 2】 In chemical formula (2), R 5 -R 7 and A + Same as in chemical formula (1).

4. The azo iron complex dye as described in claim 3, characterized in that, It also contains a diazo-diazo iron complex represented by the following chemical formula (3), 【Transformation 3】 In chemical formula (3), R 1 -R 4 and A + Same as in chemical formula (1).

5. The azo iron complex dye according to any one of claims 1-4, characterized in that, The monovalent cation is selected from at least one of alkali metal ions, ammonium ions, and monovalent alkyl-containing ammonium ions as shown in the following chemical formula (4). 【Chemistry 4】 In chemical formula (4), R 8 It is a straight-chain or branched alkyl group with 1-18 carbon atoms, R 9 and R 10 Each is an alkyl group that is independently composed of hydrogen atoms or has a straight or branched chain with 1 to 8 carbon atoms.

6. The azo iron complex dye as described in claim 4, characterized in that, The peak area ratios of the chromatograms obtained by measuring the diazo-monoazo iron complex, the monoazo-monoazo iron complex, and the diazo-diazo iron complex in high performance liquid chromatography at a wavelength of 254 nm were set to 20-70∶5-80∶0-50, respectively.

7. An ink composition, characterized in that, The dye comprising any one of claims 1-6 and an organic solvent.

8. The ink composition according to claim 7, characterized in that, For use in inkjet printers.

9. A method for preparing azo iron complex dyes, characterized in that, Through a process including iron complexation and ion exchange, the diazo-monozo iron complex shown in the following chemical formula (1) is obtained. The iron complexing process involves heating the diazo pigment (5) and the monoazo pigment (6) in a solvent to obtain an azo iron complex anion. The ion exchange process involves reacting the azo iron complex anion with an alkali metal solution and / or an ammonifying agent to introduce a cation that combines with the azo iron complex anion. 【Transformation 5】 In chemical formula (5), R 1 and R 2 Each of the following is an independent alkyl group consisting of a straight chain or a branched chain with 3-10 carbon atoms: R 3 R is an electron-withdrawing group. 4 It is a straight-chain or branched alkyl group having 1-5 carbon atoms, or a straight-chain or branched alkoxy group having 1-5 carbon atoms. 【Transformation 6】 In chemical formula (6), R 5 R is a nitro group, sulfonamide group, or halogen atom. 6 R is a hydrogen atom, a straight-chain or branched alkyl group, a nitro group, or a halogen atom with 1-8 carbon atoms. 7 It is a straight-chain or branched alkyl group with 3-12 carbon atoms or hydrogen atoms. 【Chemistry 1】 In chemical formula (1), R 1 -R 4 As in chemical formula (5), R 5 -R 7 As in chemical formula (6), A + It is a monovalent cation.

10. The method for preparing azo iron complex dyes as described in claim 9, characterized in that, In the iron complexation process, the molar ratio of the diazo pigment to the monoazo pigment is set to 2:8 to 8:2.

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