JP2006028260A - Black ink composition, ink set containing the same and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a black ink composition that does not require addition of a large amount of a color correction dye or another color correction dye, develops prints of excellent black tone and high density, has excellent weather resistance, heat resistance, water resistance (no bleeding), excellent hue and liquid stability and comprises a water-soluble short-wave dye S and a water-soluble long-wave dye L and an ink set containing the same and to provide an inkjet recording method using them. <P>SOLUTION: The black ink composition comprises a water-soluble long-wave dye L and a water-soluble short-wave dye S that contains three or more azo groups in one molecule and a naphthalene skeleton. The ink set contains the black ink composition. The inkjet recording method comprises forming an image by using the black ink composition or the ink set on an image receiving material having an ink-receiving layer containing white inorganic pigment particles on a substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a black ink composition (preferably a black ink composition for image formation (preferably an inkjet ink composition)) containing an azo dye having a specific structure and characteristics, and an ink set including the black ink composition Alternatively, the present invention relates to an ink jet recording method using an ink set.

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

  For such colorants used in ink jet recording inks, they have good solubility or dispersibility in solvents, excellent color development, high density recording, good hue, light It is robust against active gases in the environment of heat, oxidizing gases such as NOx and ozone, SOx, etc., has excellent fastness to water and chemicals, and has fixability to image receiving materials. It is required that the ink does not bleed well, has excellent storability as an ink, has no toxicity, has high purity, and can be obtained at low cost. However, it is extremely difficult to search for colorants that meet these requirements at a high level. In particular, there is a strong demand for a colorant for black ink that has a good black tone, enables high-density printing, and is robust against light, humidity, and heat.

Conventionally, disazo dyes or trisazo dyes have been used as black pigments, but these dyes alone often lack blue to green light absorption and often do not provide a good black tone. In general, a dye for color correction that absorbs blue to green light is used in combination. As such a correction dye, for example, dyes as described in Patent Document 1 and Patent Document 2 have been proposed, and black tone adjustment ability, color developability, fastness, ink storage stability, water resistance, nozzle resistance, and the like. Improvements such as clogging have been attempted.
However, the conventionally proposed color correction dyes have the problem of lack of black tone adjustment ability, such as the necessity of adding a large amount because the absorption is too short, and the need for another color correction dye. It was.

  Dyes that can absorb blue to green light are generally known, but their fastness is inferior, so the hue changes greatly upon exposure to light, heat, and active gases in the environment, and the fixability is insufficient. For this reason, almost all of the phenomena such as yellowing of the outline portion under high humidity conditions occur, and further improvement is necessary.

In view of these drawbacks, Patent Document 3 describes a black ink composition comprising a triazine dye having a maximum absorption spectrum of 435 nm in an aqueous solvent as a color correction dye and a black dye. .
However, a general black dye has a maximum absorption at 570 to 620 nm, and even when the color correction dye is used, a suitable black tone cannot be obtained in consideration of the complementary color relationship important for black tone adjustment. This is clear (Non-Patent Document 1).
Patent Document 4 describes CI Direct Red 84, but there is no disclosure of a black ink composition using this as a short wave dye and combining with a long wave dye.
Patent Document 5 describes CI Direct Red 84 in column 8, but there is no disclosure of a black ink composition which is magenta and is used as a short wave dye in combination with a long wave dye in the same manner as described above.
JP-A-9-255906 Japanese Patent No. 3178200 JP 2002-332426 A "Color Science Handbook (2nd edition)", The University of Tokyo Press, 1998, p560-562 JP-A-8-302255 JP 2000-265099 A

An object of the present invention is to solve the above problems and achieve the following objects.
That is, the object of the present invention is to enable excellent black tone and high density printing without adding a large amount or other color correction dye, and excellent weather resistance, heat resistance, water resistance (bleeding). A black ink composition comprising a water-soluble short wave dye S and a water-soluble long wave dye L, excellent in hue and liquid stability, an ink set containing the same, and an ink jet recording method using them. .

Means for solving the above problems are as follows.
1) A black ink composition comprising a water-soluble long wave dye L and a water-soluble short wave dye S having three or more azo groups in one molecule and having a naphthalene skeleton.
2) The black ink composition as described in 1) above, wherein the water-soluble short wave dye S is used as a complementary color dye of the water-soluble long wave dye L.
3) The black ink composition as described in 1) or 2) above, wherein the water-soluble shortwave dye S is contained in an amount of 0.1 to 4% by mass.
4) The black ink composition as described in any one of 1) to 3) above, wherein the water-soluble long wave dye L is an azo dye having a naphthalene skeleton.
5) The black ink composition as described in any one of 1) to 4) above, wherein the water-soluble shortwave dye S has a structure having 3 to 6 azo groups in one molecule.
6) The black ink composition as described in any one of 1) to 5) above, wherein the water-soluble long-wave dye L has 2 to 4 conjugated azo groups in one molecule.
7) The black ink composition as described in any one of 1) to 6) above, wherein the water-soluble long wave dye L has a hydroxyl group at the conjugate position of the azo group.
8) The black ink composition as described in any one of 1) to 7) above, wherein the water-soluble long wave dye L has 1 or less heterocyclic ring in a chromophore.
9) The black ink composition as described in any one of 1) to 8) above, wherein the water-soluble long wave dye L has association properties.
10) The black ink composition as described in any one of 1) to 9) above, which comprises a water-miscible organic solvent.
11) The black ink composition as described in 10) above, wherein the water-miscible organic solvent has a vapor pressure of 2000 Pa or less.
12) The water-miscible organic solvent is at least one selected from the group consisting of an alcohol compound, a heterocycle-containing organic solvent, and an alkyl ether of a polyhydric alcohol. The black ink composition as described.
13) One or more water-miscible substances selected from diethylene glycol, triethylene glycol, glycerin, triethylene glycol monobutyl ether, 1,5-pentanediol, 1,2-hexanediol, isopropanol, triethanolamine, and 2-pyrrolidone 10. The black ink composition as described in any one of 10) to 12) above, which contains an organic solvent.
14) The black ink composition as described in any one of 1) to 13) above, which comprises a surfactant.
15) The black ink composition as described in any one of 1) to 14) above, which contains a preservative.
16) The black ink composition as described in any one of 1) to 15) above, wherein the viscosity is 1 to 20 mPa · sec.
17) The black ink composition as described in any one of 1) to 16) above, wherein the surface tension is 20 to 50 mN / m.
18) The black ink composition as described in any one of 1) to 17) above, wherein the pH is 7 to 9.
19) An ink set comprising the black ink composition as described in any one of 1) to 18) above.
20) The black ink composition described in any one of 1) to 18) above or the ink set described in 19) above is used on an image receiving material having an ink receiving layer containing white inorganic pigment particles on a support. And forming an image.

  When used in ink jet recording using the above black ink composition of the present invention, an image having good black tone, high printing density, and high fastness to light and the active gas in the environment is formed. In addition, image bleeding during storage at high temperature and high humidity can be greatly improved.

Hereinafter, the present invention will be described in more detail.
[dye]
(Water-soluble short wave dye S)
The water-soluble short wave dye S (hereinafter also referred to as short wave dye S) used in the present invention is characterized by a structure having three or more azo groups in one molecule and a naphthalene skeleton.
With this structure, the short wave dye S can enhance the color developability and can give an image with good fixability because the dye plane is greatly expanded.
The number of the azo groups is preferably 3 to 6 and more preferably 4 to 6 in one molecule from the viewpoint of color developability and fixability.
The naphthalene skeleton means a structure containing a naphthalene ring, and the short wave dye S preferably contains 2 to 4 naphthalene rings in one molecule.

Further, the short wave dye S of the present invention preferably does not have a dissociable phenolic hydroxyl group present in a general pigment. Owing to such a structure, there is little change in color tone depending on the image receiving material to be used. It has preferable performance such as low reactivity with oxidizing gas such as excellent gas resistance.
Here, the dissociable phenolic hydroxyl group means a dissociable hydroxyl group substituted with an aryl group. This aryl group may be substituted with other substituents.

Further, the short wave dye S is preferably a dye which has a maximum absorption spectrum (absorption maximum: λmax) in an aqueous solvent at 440 to 540 nm and a half width at 90 nm to 200 nm and achieves broad absorption. Here, the aqueous solvent means a medium in which water is a main solvent and a dye which may contain a water-miscible organic solvent appropriately may be dissolved or dispersed. Further, the absorption spectrum means that measured by a spectrophotometer using a 1 cm cell that is usually used. The same applies to the water-soluble long wave dye L described later.
The absorption spectrum of the water-soluble short wave dye S is measured using a single compound. That is, when measuring an absorption spectrum in an aqueous solvent, the short-wave dye S does not exhibit physical properties such as a desired absorption maximum and half-value width by combining a plurality of compounds, but means that such physical properties are exhibited by one compound. To do. In the present invention, it is obvious that compounds having different absorption spectra may be used in combination as long as the short wave dye S satisfies the above structure. Furthermore, in the present invention, a short wave dye other than the short wave dye S having the molecular structure may be used in combination.
Since the short wave dye S has such absorption characteristics, it can absorb a wide range of light from blue to green, which tends to be insufficient in the absorption spectrum of the water-soluble long wave dye L such as disazo dye or trisazo dye. , Having preferable absorption characteristics as a complementary color dye.
The absorption maximum of the short wave dye S is preferably between 450 and 520 nm, particularly preferably between 460 and 500 nm.
The full width at half maximum at the absorption maximum of the short-wave dye S is preferably between 100 nm and 180 nm, and particularly preferably between 110 nm and 160 nm.

The short wave dye S of the present invention is not particularly limited as long as it has the structure defined in the present specification and can solve the above-mentioned problems, and examples thereof include polyazo dyes represented by the following general formula.
(D) n-Y
In the above general formula, D is a chromophore composed of 1 to 3 azo groups conjugated to each other and 3 to 4 aromatic rings having a naphthalene skeleton and a total of 20 or more π electrons. And n is 1 or 2, when n is 1, Y represents a hydrogen atom, and when n is 2, Y represents a divalent linking group (provided that the azo group The total is 3 or more). The aromatic ring constituting the chromophore may be a heterocyclic ring or a hydrocarbon ring, but is preferably a hydrocarbon ring. When the aromatic ring constituting the chromophore is a condensed ring, the number of π electrons on the aromatic ring is the number of π electrons as the whole condensed ring. For example, a naphthalene ring has 10 π electrons. It is. The divalent linking group represented by Y is an alkylene group, an arylene group, a heterocyclic residue, -CO-, -SOn- (n is 0, 1, 2), -NR- (R is a hydrogen atom, alkyl Group, represents an aryl group), —O—, and a divalent group obtained by combining these linking groups, and further includes an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, and a halogen atom. May have a substituent such as a hydroxyl group, a carboxyl group, a sulfamoyl group, a carbamoyl group, or a sulfonamide group. Particularly preferred examples of the linking group include —NH—CO—NH—, —NH—CS—NH—, and groups having the following general formula.

In the present specification, an alkyl group is a monovalent saturated carbonization obtained by combining linear, branched, cyclic (monocyclic or polycyclic, may be bridged or spiro in the case of polycyclic), or a combination thereof. It means a hydrogen group and is a concept including a cycloalkyl group, a cycloalkylalkyl group and the like, and further includes a substituted alkyl group when it may be substituted with a substituent.
In the present specification, the alkenyl group excludes an aromatic group obtained by combining linear, branched, cyclic (monocyclic or polycyclic, may be bridged or spiro in the case of polycyclic), or a combination thereof. This is a concept that means a monovalent unsaturated hydrocarbon group containing one or more carbon-carbon double bonds, and when it may be further substituted with a substituent, a substituted alkenyl group is included.
In the present specification, for example, a substituted alkyl group means an alkyl group in which a hydrogen atom of an alkyl group is substituted with another substituent, and the substituent can substitute one or more of each one or more. Other substituted aryl groups are the same as described above.

  In the above general formula, X represents a hydroxyl group, a sulfo group, an alkoxy group, an aryloxy group, an amino group (including an alkylamino group or an arylamino group), or an alkyl or arylsulfenyl group, and each group further has a substituent. You may have.

  For example, commercially available CIDirect Red 84, Brown 106, and Brown 202 are useful as such short-wave dye S, and CI Direct Red 84, which can be used to adjust the color tone of many black dyes and is excellent in color development, fastness, and fixing properties. Is particularly useful.

Furthermore, although the example of the short wave dye S preferably used by this invention is shown with the structure of a free acid below, it cannot be overemphasized that you may use as arbitrary salts.
Preferred counter cations include alkali metals (eg, lithium, sodium, potassium), ammonium, and organic cations (eg, pyridinium, tetramethylammonium, guanidinium).

Among them, CI Direct Red 84 (Na salt of the above compound example 2) and Brown 106 (Na salt of the above compound example 14) are suitable as commercially available dyes, and are used for color tone adjustment of many black dyes. CIDirect Red 84 is particularly useful because it has excellent color development, fastness and fixing properties.
In addition, the short wave dye S other than the commercially available dye can be easily obtained from commercially available raw materials according to the synthesis route of CI Direct Red 84 or Brown 106 described in Color Index Vol. 4 (issued by The Society of Dyers and Colorists). Can be synthesized.

  The black ink composition of the present invention preferably contains 0.1 to 4% by mass, preferably 0.5 to 3.0% by mass, particularly preferably 1.0 to 2.5% by mass of the short wave dye S. Is also possible.

(Water-soluble long wave dye L)
The water-soluble long wave dye L (hereinafter also referred to as long wave dye L) used in the present invention preferably has a structure having a naphthalene skeleton, and more preferably has a structure represented by general formulas 1 to 3 described later. .
The long wave dye L preferably has 2 to 4 azo groups conjugated to each other in one molecule.
Further, the long wave dye L has a hydroxyl group at the conjugated position of the azo group, or the number of heterocycles in the chromophore is 1 or less. This is preferable for ensuring a wide absorption characteristic with a wide half-value width and ink stability. Here, the conjugated position means a substitution position having a conjugated relationship with the azo group, and the hydroxyl group is preferably substituted at the ortho position or the para position with respect to the substitution position of the azo group.
In general, a dye having a hydroxyl group at the conjugated position of an azo group may be inferior in fastness to light or active gas in the air depending on the type of image receiving material and the storage conditions of the printed matter. What has the property which has an associative property and can suppress reaction physically is still more preferable.
Whether the dye is in an associated state is determined by measuring the visible absorption spectrum by changing the dye concentration and examining the change in absorption maximum wavelength, molar extinction coefficient, and waveform to determine whether the dye has an association property. It can be easily judged from the comparison between the solution physical properties and the absorption spectrum of the dye on the image receiving material.
Specifically, as defined in Japanese Patent Application No. 2004-65569, a molar extinction coefficient (ε1) at a maximum wavelength of absorption in the visible region, measured using a 0.1 mmol / l dye aqueous solution using a cell having an optical path length of 1 cm, A dye that satisfies the relationship of ε1 / ε2> 1.2 between the molar extinction coefficients (ε2) when a 0.2 mol / l aqueous solution is measured using a liquid crystal cell having an optical path length of 5 μm is preferable.

The long wave dye L preferably has a maximum absorption spectrum (absorption maximum) in an aqueous solvent of 550 to 700 nm and a half-value width of 100 nm or more (preferably 120 to 500 nm, more preferably 120 to 350 nm).
The absorption spectrum of the long wave dye L is measured using a single compound. That is, when measuring an absorption spectrum in an aqueous solvent, the long wave dye L does not show physical properties such as a desired absorption maximum and half width by combining a plurality of compounds, but means that such physical properties are shown by one compound. To do. In the present invention, as long wave dye L satisfies the above structure, it is obvious that compounds having different absorption spectra may be used in combination. Furthermore, in the present invention, a long wave dye other than the long wave dye L having the molecular structure may be used in combination.

Among the long wave dyes L preferably used in the present invention, those corresponding to the following general formula are particularly preferable.
In the following general formula, the dye is represented by the structure of a free acid, but it goes without saying that it may be used in the form of a salt in actual use.

In the above general formulas 1 to 3, when there are a plurality of substituents represented by the same symbol in the same molecule, they may be the same as or different from each other. X represents an amino group, a hydroxyl group or a hydrogen atom. Y represents a hydrogen atom or an amino group. R represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an aryl group, a heterocyclic group, an acyl group, or a sulfonyl group, which may have a substituent. Representative examples of the substituent that may be included include halogen atoms, ionic hydrophilic groups (sulfo groups, carboxyl groups, etc.), alkoxy groups, hydroxy groups, acylamino groups, acyl groups, carbamoyl groups, sulfamoyl groups, and the like. Can be cited as a thing. n represents an integer of 0 to 3, and the sulfo group may be substituted at any position of the benzene ring or naphthalene ring. A ₁ and A ₂ each represent a monovalent aromatic group or a heterocyclic group. B represents a divalent aromatic group or a heterocyclic group. A ₁ and A ₂ may be further substituted with an azo group. A ₁ , A ₂ and B may further have a substituent. The number of heterocyclic rings contained in the chromophore of the dye is preferably 1 or less. Further, a part of the dyes represented by these general formulas may be dissociated to form a chelate dye coordinated with a transition metal.

Among the above general formulas, the dyes represented by the general formula 1 or the general formula 2 are preferable, and among them, the dyes of the general formula 1 are particularly preferable. Among the dyes of the general formula 1, those in which X is an amino group or a hydroxyl group are preferred, and those having a hydroxyl group are particularly preferred. Further, from the viewpoint of fastness, it is preferable that an electron-withdrawing group is substituted on the dye, or any of A1, A2, and B is a heterocyclic ring.
Preferred examples of the electron withdrawing group include a nitro group, a cyano group, a halogen atom, a sulfamoyl group, a carbamoyl group, and an ester group.
Preferable examples of the heterocyclic ring include pyrazole, thiazole, isothiazole, oxazole, isoxazole and pyridine which may have a condensed ring.
Particularly preferred among the general formula 1 is a compound represented by the following general formula 4.

In General Formula 4, A ₃ and A ₄ each independently represent a heterocyclic group or an aryl group represented by General Formula 5. n represents an integer of 0 to 3.

  In the general formula 5, EWG (Electron Withdrawing Group) is an electron-withdrawing group selected from the group consisting of a nitro group, a cyano group, an azo group, a sulfamoyl group, a carbamoyl group, and an ester group, Represents an azo group. Z represents a substituent selected from an alkyl group, an alkoxy group, a sulfo group, a carboxyl group, an amino group, and an acylamino group. The substituent represented by EWG or Z may further have a substituent. p represents an integer of 0 to 4. q represents an integer of 0 to 3, preferably 1 or 2.

Although the example of the preferable long wave dye L is shown with the structure of a free acid below, it cannot be overemphasized that you may use as arbitrary salts.
Preferred counter cations include alkali metals (eg, lithium, sodium, potassium), ammonium, and organic cations (eg, pyridinium, tetramethylammonium, guanidinium).

  In addition to the dyes represented by the above formulas, JP-A-10-130557, JP-A-9-255906, JP-A-7-97541, JP-A-6-234944, European Patent 982371A1, JP-A-2002-302619, 2002-2002. No. 327131, No. 2002-265809, International Patent Publication Nos. 2000-43450, 2000-43451, 2000-43451, 2000-43453, 2003-106572, 2003-104332, JP 2003 The dyes described in JP-A No. 238862, JP-A-2004-83609, and the respective publications can also be preferably used as the long wave dye L.

The black ink composition of the present invention preferably contains 0.2 to 30% by mass, particularly preferably 0.5 to 15% by mass, and most preferably 1 to 10% by mass of the long wave dye L in the ink. preferable.
The ratio of the short wave dye S and the long wave dye L of the present invention is preferably 1 to 50% by mass, more preferably 5 to 40% by mass with respect to the long wave dye L. Most preferably, it is -30 mass%.

[Black ink composition]
The black ink composition of the present invention means an ink composition containing at least a short wave dye S and a long wave dye L. The black ink composition of the present invention can contain a medium, but when a solvent is used as the medium, it is particularly suitable as an ink for ink jet recording.
The black ink composition of the present invention can be prepared by dissolving and / or dispersing the dye of the present invention in a lipophilic medium or aqueous medium as a medium. Preferably, an aqueous medium is used. As the aqueous medium, a mixture containing water as a main component and optionally adding a water-miscible organic solvent can be used. Examples of the water miscible organic solvent include those described in JP-A No. 2003-306623. In addition, the said water miscible organic solvent may use 2 or more types together. The black ink composition of the present invention includes an ink composition excluding a medium.
Hereinafter, although the composition component of the black ink composition of the present invention will be described in detail, the information relating to the composition also applies to ink compositions of other colors when the ink set containing the black ink composition of the present invention is used. Can be used.

(Water-miscible organic solvent)
The vapor pressure of the water-miscible organic solvent is preferably 2000 Pa or less. This vapor pressure is a value measured under the condition of 20 ° C. Such a water-miscible organic solvent having a vapor pressure has a drying prevention function for preventing clogging due to a dry operation at an ink ejection port and a penetration promoting function for allowing the ink to permeate the paper better.

As the water-miscible organic solvent used in the present invention, those having a vapor pressure at 20 ° C. of 2000 Pa or less may be used alone or in combination of two or more. When a plurality of water-miscible organic solvents are used, the vapor pressure at 20 ° C. of at least one of the water-miscible organic solvents is preferably 2000 Pa or less.
Specific examples of the water-miscible organic solvent having an anti-drying function include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1, Polyhydric alcohols represented by 2,6-hexanetriol, acetylene glycol derivatives, glycerin, trimethylolpropane, etc., ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or Lower alkyl ethers of polyhydric alcohols such as butyl) ether, heterocyclic rings such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethylmorpholine , Sulfolane, dimethyl sulfoxide, sulfur-containing compounds such as 3-sulfolene, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Of these, polyhydric alcohols such as glycerin and diethylene glycol are more preferred.

Examples of water-miscible organic solvents having a penetration promoting function include lower monoalkyl ethers of polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol monomethyl ether, monoethyl ether, mono- n-butyl ether, mono-iso-butyl ether, mono-n-hexyl ether, etc.) and lower dialkyl ethers of polyhydric alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, dimethyl ether of propylene glycol, diethyl ether, etc.) Can be mentioned.
The water-miscible organic solvent used in the present invention may have both the above functions and other functions such as a viscosity adjusting function.

The water-miscible organic solvent preferably contains one or more selected from the group consisting of alcohol compounds, heterocycle-containing organic solvents, and alkyl ethers of polyhydric alcohols.
Examples of the alcohol compound include monohydric alcohols having 1 to 4 carbon atoms and alkanediols.
As the monohydric alcohol having 1 to 4 carbon atoms, methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 1-butanol, 2-methyl-1-propanol (isobutanol), and tert-butanol are preferable.
Examples of the alkanediol include 1,2-alkanediol (for example, 1,2-pentanediol, 1,2-hexanediol), terminal diol (for example, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, etc.), branched diols (for example, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,4-butanediol, 2-methyl-2,4-pentanediol, 3 -Methyl-1,5-pentanediol, 3-methyl-1,3-butanediol, 2-methyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol) and the like. Used alone or in combination.
Examples of the heterocycle-containing organic solvent include compounds represented by the following general formula (A).

In the general formula (A), X ₁ represents a carbonyl or a group containing a hetero atom. Z ₁ represents an atomic group that can form a heterocycle.
Examples of X ₁ include carbonyl group, oxycarbonyl group, carbonate group, amide group, urethane group, ureido group, amino group, imino group, ether group, thioether group, phosphoric acid derivative group, phosphonic acid derivative group, sulfonyl group Groups, sulfonamido groups, sulfonylurea groups, and the like, among which amide groups are preferred.
Z represents an atomic group that can form a heterocycle. Z ₁ may be a ring composed of only carbon atoms, but may further contain a heteroatom in the chain of carbon atoms. The ring may or may not have aromaticity. Furthermore, a compound of a type in which a plurality of rings are condensed may be formed.
The compound represented by the general formula (A) can have various substituents in its structure. For example, an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n -Decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms). For example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms). , For example, propargyl, 3-pentynyl, etc.), an aryl group (preferably having 6 to 30 carbon atoms, more preferably carbon number) To 20 and particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, etc.), amino groups (preferably having 0 to 20 carbon atoms, more preferably 0 to 12 carbon atoms, Particularly preferably, it has 0 to 6 carbon atoms, and examples thereof include amino, methylamino, dimethylamino, diethylamino, diphenylamino, dibenzylamino and the like, and an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably carbon. 1 to 12, particularly preferably 1 to 8 carbon atoms such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, Particularly preferably, it has 6 to 12 carbon atoms, and examples thereof include phenyloxy and 2-naphthyloxy.), Acyl groups (preferably Or a carbon number of 1 to 16, more preferably a carbon number of 1 to 16, particularly preferably a carbon number of 1 to 12, such as acetyl, benzoyl, formyl, pivaloyl, etc.), an alkoxycarbonyl group (preferably carbon 2 to 20, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group (preferably 7 to 20 carbon atoms). , More preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl, etc.), an acyloxy group (preferably 2 to 20 carbon atoms, more preferably 2 to 2 carbon atoms). 16 and particularly preferably 2 to 10 carbon atoms, such as acetoxy and benzoyloxy. An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino. ), An alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino A group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino), a sulfonylamino group (preferably having a carbon number) 1-20, more preferably 1-16 carbon atoms, particularly preferably 1-12 carbon atoms, such as methylsulfonylamino, phenylsulfonylamino, etc.), sulfamoyl groups (preferably having 0-20 carbon atoms, More preferably, it has 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms. Moyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to carbon atoms). For example, carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms). For example, methylthio, ethylthio, etc.), arylthio groups (preferably having 6-20 carbon atoms, more preferably 6-16 carbon atoms, particularly preferably 6-12 carbon atoms, such as phenylthio). ), A sulfonyl group (preferably having 1 to 20 carbon atoms, more preferably charcoal) 1 to 16, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably C1-C12, for example, methylsulfinyl, phenylsulfinyl, etc.), ureido group (preferably C1-C20, more preferably C1-C16, particularly preferably C1-C12 Yes, for example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, For example, diethyl phosphoric acid amide, phenyl phosphoric acid amide, etc.), hydroxy group, mercapto group, halogen atom (for example, fluorine source) Child, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms) Preferably, it has 1 to 12 carbon atoms, and the hetero atom includes, for example, a nitrogen atom, an oxygen atom, and a sulfur atom. Specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxa Examples include zolyl, benzimidazolyl, benzothiazolyl, carbazolyl, azepinyl and the like. ), A silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms, and examples thereof include trimethylsilyl and triphenylsilyl). These substituents may be further substituted. When there are two or more substituents, they may be the same or different. If possible, they may be linked to each other to form a ring.
The compound represented by the general formula (A) is preferably monocyclic and is preferably liquid under normal temperature and pressure conditions. Further, various compounds such as an oil-soluble structure and a water-soluble structure can be used, and a water-soluble compound is preferable.
In the following, compounds preferably used as the compound represented by the general formula (A) include 2-pyrrolidone, ε-caprolactam, tetrahydrofuran, 1,4-dioxane, 1,3-dimethylimidazolidinone (for example, 1 , 3-dimethylimidazolidin-2-one), N-methylpyrrolidone, ethylene urea, sulfolane, pyridine, pyrazine, morpholine, 1-methyl-2-pyridone, 2-methyl-2-oxazoline, 2-ethyl-2- Oxazoline, 2,4,4-trimethyl-2-oxazoline and the like can be mentioned and used alone or in combination, but the present invention is of course not limited thereto.

  Examples of alkyl ethers of polyhydric alcohols include lower monoalkyl ethers of polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol monomethyl ether, monoethyl Ether, mono-n-butyl ether, mono-iso-butyl ether, mono-n-hexyl ether, etc.) and lower dialkyl ethers of polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, Dimethyl ether, diethyl ether, di-n-butyl ether, di-iso-butyl ether of trilopyrene glycol, di-n- Include hexyl ether) and the like, used alone or in combination.

The black ink composition of the present invention comprises a water-miscible organic solvent such as diethylene glycol, triethylene glycol, glycerin, triethylene glycol monobutyl ether, 1,5-pentanediol, 1,2-hexanediol, isopropanol, triethanolamine. It is preferable to contain at least one selected from 2-pyrrolidone.
The content of the water-miscible organic solvent used in the present invention in the black ink composition is usually 1 to 80% by mass, preferably 5 to 60% by mass, and more preferably 10 to 50% by mass.
In the present invention, a water miscible organic solvent having a vapor pressure at 20 ° C. exceeding 2000 Pa other than the water miscible organic solvent used in the present invention may be used in an amount of 20% by mass or less in the ink. Examples of the water-miscible organic solvent that can be used in combination include ethanol.

(Surfactant)
The black ink composition of the present invention preferably contains a surfactant.
By adding a surfactant to the black ink composition of the present invention and adjusting the liquid physical properties of the ink such as surface tension, the ink ejection stability is improved, the water resistance of the image is improved, and the printed ink bleeds. It is possible to give an excellent effect to prevention of the above.
Examples of the surfactant include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate esters, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl sulfates. Anionic surfactants such as ester salts, cationic surfactants such as fatty amine salts, quaternary ammonium salts, alkylpyridinium salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan Fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethyleneoxypropylene block copolymer, acetylene Nonionic surfactants polyoxyethylene oxide, etc., amino acids and amphoteric surfactants betaines, fluorine, and the like silicon compound. These can be used alone or in combination of two or more.
From the viewpoint of the above effects, a nonionic surfactant is preferable from the viewpoint of ink ejection stability and paper permeability. In particular, compounds represented by the following general formula (I) or (II) or general formula (III) are more preferable.
Polyhydric alcohol mono- or dialkyl ethers (eg, triethylene glycol monobutyl ether, triethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, etc.) also have surface activity. However, in the present invention, these are regarded as penetrants and not as surfactants.

  First, the compound represented by formula (I) will be described.

In the general formula (I), R ²¹ represents an alkyl group having 5 to 40 carbon atoms, preferably 8 to 18 carbon atoms, which may be linear or branched and may be substituted.
Examples of the group that can be substituted for the alkyl group represented by R ²¹ include an aryl group (eg, phenyl, o-tolyl, p-tolyl, pt-butylphenyl), an alkoxy group (eg, methoxy, ethoxy, n-butoxy). Etc.), halogen atoms (for example, chlorine atom, bromine atom) and the like.
Specific examples of the alkyl group represented by R ²¹ include n-pentyl, n-hexyl, n-octyl, n-decyl, n-dodecyl, n-pentadecyl, n-octadecyl, 2-ethylhexyl, 1-ethylpentyl. 1-n-butylpentyl, 1-n-pentylhexyl, 1-n-hexylheptyl, 1-n-heptyloctyl, 1-n-octylnonyl, 6-methoxyhexyl, 2-phenylethyl and the like. it can.
m ₁ represents an average addition mole number of ethylene oxide, 2 to 40, preferably from 3 to 30, particularly preferably from 3 to 20.
Of the compounds represented by the general formula (I), a compound represented by the following general formula (I-1) is particularly preferable.

In General Formula (I-1), R ²² and R ²³ each represent a saturated hydrocarbon having 4 to 10 carbon atoms, and the total number of carbon atoms of R ²² and R ²³ is 8 to 18. m ₁₁ represents an average addition mole number of ethylene oxide is 3 to 20. Examples of the saturated hydrocarbon having 4 to 10 carbon atoms represented by R ²² and R ²³ include n-butyl, i-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n- Nonyl, n-decyl and the like can be mentioned. The total number of carbon atoms of R ²² and R ²³ is 8 to 18, and 8 to 16 is more preferable. m ₁₁ is 3 to 20, more preferably from 5 to 20, more preferably from 6 to 18.
Although the specific example of a compound represented by general formula (I) below is shown, it is not limited to these.

  Specific examples of the compound represented by the general formula (I-1) are shown in Table 1 below, but are not limited thereto.

  Next, the compound represented by formula (II) will be described.

In the general formula (II), R ²⁴ represents an alkyl group having 5 to 40 carbon atoms, preferably 5 to 30 carbon atoms, which may be linear or branched, and may be substituted.
Examples of the group that can be substituted for the alkyl group represented by R ²⁴ include an aryl group (eg, phenyl, o-tolyl, p-tolyl, pt-butylphenyl), an alkoxy group (eg, methoxy, ethoxy, n-butoxy). Etc.), halogen atoms (for example, chlorine atom, bromine atom) and the like. Specific examples of the alkyl group represented by R ²⁴ include n-pentyl, n-hexyl, n-octyl, n-decyl, n-dodecyl, n-pentadecyl, n-octadecyl, 2-ethylhexyl, 1-ethylpentyl. 1-n-butylheptyl, 1-n-hexylnonyl, 1-n-heptyldecyl, 1-n-octyldodecyl, 1-n-decyltetradecyl, 6-methoxyhexyl, 2-phenylethyl and the like. it can.
m ₂ represents an average addition number of ethylene oxide, 2 to 40, preferably from 3 to 30, particularly preferably from 4 to 20.
Of the compounds represented by the general formula (II), a compound represented by the following general formula (II-1) is particularly preferable.

In general formula (II-1), R ²⁵ and R ²⁶ are each a saturated hydrocarbon group having 2 to 20 carbon atoms, preferably 4 to 13 carbon atoms. Examples of the saturated hydrocarbon group having 2 to 20 carbon atoms represented by R ²⁵ and R ²⁶ include ethyl, n-butyl, i-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and 2-ethylhexyl. , N-nonyl, n-decyl, n-dodecyl, n-hexadecyl, n-octadecyl and the like. m ²¹ represents an average addition mole number of ethylene oxide, 2 to 40, 3 to 30 are preferred.
Although the specific example of a compound represented by general formula (II) below is shown, it is not limited to these.

  Examples of the compound represented by the general formula (II-1) include a polyethylene oxide adduct of one-terminal ester of 2-butyloctanoic acid polyethylene oxide and undecan-6-ol. Specific examples of the compound represented by the general formula (II-1) are shown in Table 2 below, but are not limited thereto.

The compound represented by the general formula (I) or the general formula (II) can be synthesized by using a known method. For example, Takehiko Fujimoto's revised edition “Introduction to New Surfactant” (1992) ) It can be obtained by the method described in pages 94 to 107.
Next, the compound represented by formula (III) will be described.

In the formula, R ³¹ and R ³² each independently represents an alkyl group having 1 to 18 carbon atoms.
More specifically, R ³¹ and R ³² each independently represents an alkyl group having 1 to 18 carbon atoms (for example, methyl, ethyl, n-propyl, butyl, hexyl, octyl, decyl, dodecyl, etc.) and substituted. It may be. Examples of the substituent include an alkyl group (for example, methyl, ethyl, isopropyl and the like), an alkoxy group (for example, methoxy, ethoxy and the like), a halogen atom (for example, a chlorine atom and a bromine atom) and the like. Among these, as R ³¹ and R ³² , an unsubstituted linear alkyl group having 1 to 12 carbon atoms or an unsubstituted branched alkyl group is preferable, and particularly preferable specific examples thereof include methyl, ethyl, n-butyl, 2- Examples include methylbutyl and 2,4-dimethylpentyl.
R ³² represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, and the alkyl group and the phenyl group may be substituted.
Examples of the substituent for the alkyl group represented by R ³³ include an alkyl group (for example, methyl, ethyl, isopropyl and the like), an alkoxy group (for example, methoxy, ethoxy and the like), and a phenyl group. Examples of the substituent of the phenyl group of R ³³ include an alkyl group (eg, methyl, ethyl, isopropyl, etc.), an alkoxy group (eg, methoxy, ethoxy, etc.), a halogen atom (eg, fluorine atom, chlorine atom, bromine atom), etc. Can be mentioned. Among R ³³ , a hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferable, and a hydrogen atom is particularly preferable.
X is a hydrogen atom,

R ³⁴ and R ³⁵ each independently represents an alkyl group having 1 to 18 carbon atoms. Preferable substituents and specific examples of R ³⁴ and R ³⁵ are substituents and specific examples selected from the same group as R ³¹ and R ³² described above. R ³⁶ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, and preferred specific examples thereof are substituents and specific examples selected from the same group as R ³³ described above.
m ³ and m ⁴ each represent an average number of moles of ethylene oxide added, and m ³ + m ⁴ is 0 to 100, preferably 0 to 50, particularly preferably 0 to 40.
Here, when m ³ = 0, R ³³ represents a hydrogen atom, and when m ⁴ = 0, R ³⁶ represents a hydrogen atom. When X represents a hydrogen atom, m ³ represents 1 to 100, preferably 1 to 50, particularly preferably 1 to 40.
Of the compounds represented by the general formula (III), a compound represented by the following general formula (III-1) is particularly preferable.

In the formula, R ³⁷ , R ³⁸ , R ³⁹ and R ⁴⁰ each independently represent an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. m ₃₁ and m ₄₁ each represent the number of moles of ethylene oxide added, and the sum thereof is 0 to 40, preferably 2 to 20.
Although the specific example of a compound represented by general formula (III) or general formula (III-1) below is shown, it is not limited to these.

The compound represented by the general formula (III) or the general formula (III-1) can be synthesized using a known method. For example, Takehiko Fujimoto's revised edition “Introduction to New Surfactant” ( (1992), pages 94 to 107, and the like.
Moreover, the compound represented by general formula (III) or general formula (III-1) can also be easily obtained as a commercial item, and as the specific brand name, it is Surfinol 61,82,104,420. , 440, 465, 485, 504, CT-111, CT-121, CT-131, CT-136, CT-141, CT-151, CT-171, CT-324, DF-37, DF-58, DF -75, DF-110D, DF-210, GA, OP-340, PSA-204, PSA-216, PSA-336, SE, SE-F, Dinol 604 (above, Nissin Chemical Co., Ltd. and Air Products & Chemicals) ), Orphine A, B, AK-02, CT-151W, E1004, E1010, P, SPC, STG, Y, 32W Science Co., Ltd.).
Examples of the compound represented by the general formula (III-1) include ethylene oxide adducts of acetylenic diols (SURFYNOL series (Air Products & Chemicals)) and acetylenic diols such as 2,4,7,9-tetra Methyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,5-dimethyl-3-hexyne-2,5-diol and the like are preferable, and molecular weight is particularly preferable. Having a molecular weight of 300 to 900 is more preferable, and a molecular weight of 400 to 900 is particularly preferable.
As the surfactant to be contained in the black ink composition in the present invention, it is preferable that precipitation and separation from the ink hardly occur and the foaming property is small. From this viewpoint, the hydrophobic part is a double-stranded or hydrophobic part. Branched anionic surfactants, anionic or nonionic surfactants having a hydrophilic group near the center of the hydrophobic site, and nonionics with a hydrophobic site that is double-stranded or a hydrophobic site is branched A surfactant is preferred. Of these, nonionic surfactants are preferred, and from this viewpoint, the nonionic surfactants having a hydrophobic site double-stranded or a hydrophobic site branched are represented by the general formula (I-1) or the general formula (II-1). The compound represented by general formula (III-1) is preferable as the nonionic surfactant having a hydrophilic group near the center of the hydrophobic portion.

  Examples of the surfactant include an ethylene oxide adduct of polypropylene glycol. For example, a compound represented by the following general formula (IV) is preferable.

  In the formula, x, y and z represent integers, and y is preferably an integer of 12 to 60, and x + z is preferably an integer of 5 to 25.

As a compound represented by general formula (IV), Asahi Denka Co., Ltd. Adeka Pluronic L61, Adeka Pluronic L62, Adeka Pluronic L63, Adeka Pluronic L64, Adeka Pluronic L42, Adeka Pluronic L43, Adeka Pluronic L44, Adeka Pluronic L31, Examples include Adeka Pluronic L34, but the present invention is not limited to these.

  The surfactant content in the black ink composition of the present invention is 0.05 to 50 g / L, preferably 0.05 to 30 g / L, and more preferably 0.1 to 20 g / L. When the amount of the surfactant in the black ink composition is less than 0.05 g / L, the print quality tends to be remarkably lowered, such as a decrease in ejection stability, occurrence of bleeding at the time of color mixing, and generation of whiskers. On the other hand, if the amount of the surfactant in the black ink composition is more than 50 g / L, printing failure may occur due to ink adhesion to the hard surface during ejection.

(Preservative)
The present invention preferably contains a preservative.
In the present invention, the preservative refers to those having a function of preventing the generation and growth of microorganisms, particularly bacteria and fungi.
Various preservatives that can be used in the present invention can be used.
First, inorganic preservatives (such as silver ion-containing materials) and salts containing heavy metal ions can be mentioned. Organic preservatives include quaternary ammonium salts (tetrabutylammonium chloride, cetylpyridinium chloride, benzyltrimethylammonium chloride, etc.), phenol derivatives (phenol, cresol, butylphenol, xylenol, bisphenol, etc.), phenoxyether derivatives (phenoxyethanol) Etc.), heterocyclic compounds (benzotriazole, 1,2-benzisothiazolin-3-one, etc.), acid amides, carbamic acid, carbamates, amidine / guanidine, pyridines (sodium pyridinethione-1-oxide, etc.) , Diazines, triazines, pyrrole / imidazoles, oxazoles / oxazines, thiazoles / thiadiazines, thioureas, thiosemicarbazides, dithiocarbamates, sulfur , Sulfoxides, sulfones, sulfamides, antibiotics (penicillin, tetracycline, etc.), sodium dehydroacetate, sodium benzoate, p-hydroxybenzoic acid ethyl ester, and salts thereof alone or in combination Can be used. In addition, as the antiseptic, those described in the antibacterial and microscopic handbook (Technical Hall: 1986), the antibacterial and antifungal encyclopedia (edited by the Japanese Society for Antibacterial and Antifungal Society), etc. can be used.
Various compounds such as those having an oil-soluble structure and a water-soluble structure can be used, but a water-soluble compound is preferable.
In particular, in the present invention, when two or more of these preservatives are used in combination, the ejection stability of the ink over a long period of time is remarkably improved, and the effects of the present invention are further improved. When two or more types are combined, the preservative species preferably have a skeleton having a different chemical structure. Moreover, when it contains 2 or more types of preservatives, it is preferable that at least 1 type of preservatives is a heterocyclic compound. For example, the combination of a heterocyclic compound and an antibiotic, the combination of a heterocyclic compound and a phenol derivative, etc. are mentioned preferably. The content ratio in the case of combining two kinds of preservatives is not particularly limited, but a range of preservative A / preservative B = 0.01 to 100 (mass ratio) is preferable.
The addition amount (total amount) of the preservative can be used in a wide range, but is preferably 0.001 to 10% by mass, more preferably 0.1 to 5% by mass in the black ink composition.

  In addition to the above components, the black ink composition of the present invention further comprises an anti-bleeding agent, an antifoaming agent, a bronze improving agent, an ozone resistance improving agent, a chelating agent, an anti-drying agent (wetting agent), a penetration accelerator, and an ultraviolet absorber. It is preferable to contain at least one additive selected from the group consisting of an agent, an antioxidant, a viscosity modifier, a dispersant, a rust inhibitor, and a pH adjuster. The black ink composition of the present invention can be appropriately selected and used in an appropriate amount. The above-described components and these additives include one type of compound that can perform one or more functions. Therefore, in the compounding ratio of these additives, the handling of the additive component in the case where the functions overlap is assumed to be included in each functional component independently.

(Anti-bleeding agent)
Examples of the anti-bleeding agent include betaine surfactants.
The betaine surfactant here refers to a compound having both a cationic site and an anionic site in the molecule and having surface activity. Examples of the cationic site include an aminic nitrogen atom, a nitrogen atom of a heteroaromatic ring, a boron atom having four bonds with carbon, and a phosphorus atom. Of these, an amine nitrogen atom or a nitrogen atom of a heteroaromatic ring is preferable. Among them, a quaternary nitrogen atom is particularly preferable. Examples of the anionic site include a hydroxyl group, a thio group, a sulfonamide group, a sulfo group, a carboxyl group, an imide group, a phosphoric acid group, and a phosphonic acid group. Among these, a carboxyl group and a sulfo group are particularly preferable. The charge of the whole surfactant molecule may be any of cation, anion, and neutral, but is preferably neutral.
Specific examples of betaine surfactants are shown below, but the present invention is not limited thereto.

In general formula (V), R < ₁ > -R < ₃ > represents an alkyl group, an aryl group, and a heterocyclic group, and each may connect with each other to form a cyclic structure. L represents a divalent linking group. However, any of the groups represented by R _{1 to} R ₃ and L contains a group having 8 or more carbon atoms.

In the general formula (V), R _{1 to} R ₃ are each independently an alkyl group (which may be substituted. Preferably, it is a group having 1 to 20 carbon atoms, more preferably a group having 1 to 16 carbon atoms. A methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a dodecyl group, a cetyl group, a stearyl group, an oleyl group), an aryl group (which may be substituted, preferably having 6 to 20 carbon atoms, More preferably, it is a group having 6 to 14 carbon atoms, for example, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a cumyl group, a dodecylphenyl group, etc.), a heterocyclic group (which may be substituted, preferably a carbon number). A group having 2 to 20 carbon atoms, more preferably a group having 2 to 12 carbon atoms, such as a pyridyl group and a quinolyl group, which may be linked to each other to form a cyclic structure. Specific examples of the cyclic structure include a piperidine ring and a morpholine ring. R _{1 to} R ₃ are particularly preferably alkyl groups.

  L represents a divalent linking group. As this example, a divalent linking group containing an alkylene group or an arylene group as a basic structural unit is preferable. You may contain hetero atoms, such as an oxygen atom, a sulfur atom, and a nitrogen atom, in a connection main chain part.

Various substituents can be substituted for R _{1 to} R ₃ or L. For example, an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n -Decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms). For example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms). , For example, propargyl, 3-pentynyl, etc.), an aryl group (preferably having 6 to 30 carbon atoms, more preferably carbon number) To 20 and particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, etc.), amino groups (preferably having 0 to 20 carbon atoms, more preferably 0 to 12 carbon atoms, Particularly preferably, it has 0 to 6 carbon atoms, and examples thereof include amino, methylamino, dimethylamino, diethylamino, diphenylamino, dibenzylamino and the like, and an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably carbon. 1 to 12, particularly preferably 1 to 8 carbon atoms such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, Particularly preferably, it has 6 to 12 carbon atoms, and examples thereof include phenyloxy and 2-naphthyloxy.), Acyl groups (preferably Or a carbon number of 1 to 16, more preferably a carbon number of 1 to 16, particularly preferably a carbon number of 1 to 12, such as acetyl, benzoyl, formyl, pivaloyl, etc.), an alkoxycarbonyl group (preferably carbon 2 to 20, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group (preferably 7 to 20 carbon atoms). , More preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl, etc.), an acyloxy group (preferably 2 to 20 carbon atoms, more preferably 2 to 2 carbon atoms). 16 and particularly preferably 2 to 10 carbon atoms, such as acetoxy and benzoyloxy. An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino. ), An alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino A group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino), a sulfonylamino group (preferably having a carbon number) 1-20, more preferably 1-16 carbon atoms, particularly preferably 1-12 carbon atoms, such as methanesulfonylamino, benzenesulfonylamino, etc.), sulfamoyl groups (preferably 0-20 carbon atoms, More preferably, it has 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms. Moyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to carbon atoms). For example, carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms). For example, methylthio, ethylthio, etc.), arylthio groups (preferably having 6-20 carbon atoms, more preferably 6-16 carbon atoms, particularly preferably 6-12 carbon atoms, such as phenylthio). ), A sulfonyl group (preferably having 1 to 20 carbon atoms, more preferably charcoal) 1 to 16, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably C1-C12, for example, methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably C1-C20, more preferably C1-C16, particularly preferably C1-C12 Yes, for example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, For example, diethyl phosphoric acid amide, phenyl phosphoric acid amide, etc.), hydroxy group, mercapto group, halogen atom (for example, fluorine source) Child, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms) Preferably, it has 1 to 12 carbon atoms, and the hetero atom includes, for example, a nitrogen atom, an oxygen atom, and a sulfur atom. Specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxa Examples include zolyl, benzimidazolyl, benzothiazolyl, carbazolyl, azepinyl and the like. ), A silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms, and examples thereof include trimethylsilyl and triphenylsilyl). These substituents may be further substituted. When there are two or more substituents, they may be the same or different. If possible, they may be linked to each other to form a ring. A plurality of betaine structures may be contained via R _{1 to} R ₃ or L.

In the compound represented by the general formula (V) of the present invention, any of the groups represented by R _{1 to} R ₃ and L contains a group having 8 or more carbon atoms. Among these, those containing a long-chain alkyl group having 8 or more carbon atoms in R _{1 to} R ₃ are particularly preferable.

  Specific examples of the compound represented by the general formula (V) of the present invention are shown below, but the present invention is of course not limited thereto.

  The preferred addition amount of the betaine surfactant has a wide range, but is preferably 0.001 to 50% by mass, more preferably 0.01 to 20% by mass in the black ink composition.

(Defoamer)
The antifoaming agent in the present invention refers to a compound which is present on the surface of the liquid itself instead of the causative agent of foaming and has no power to impart a repulsive force to resist the thinning of the foam film. Specific examples include alcohols, ethers, fatty acid esters, metal stones, phosphate esters, silicons, and nonionic surfactants.

  Examples of alcohols include methanol, ethanol, butanol, octanol and the like.

  Examples of fatty acid esters include isoamyl stearate, succinic acid diester, diethylene glycol distearate, oxyethylene sorbitan monolaurate and the like, and commercially available products include Nopco KF manufactured by NopcoChem. Co.

  Examples of ethers include di-t-amylphenoxyethanol, 3-heptylcellosolve, nonylcellosolve, 3-heptylcarbitol and the like, and commercially available products such as Bionin K-17 manufactured by Takemoto Yushi Co., Ltd., Nopco manufactured by San Nopco Co., Ltd. DF122-NS may be mentioned.

  Examples of metal soaps include aluminum stearate and potassium oleate, and commercial products include Nopco DF122-NS manufactured by San Nopco Co., Ltd.

  Examples of silicones include silicone oil, silicone emulsion, and organically modified silicone oil. Commercially available products include SN Deformer 5016 manufactured by Sannopco, Surfynol DF-58, Surfynol DF-695 manufactured by Air Products, Toray Dow Examples thereof include SM-5513 manufactured by Corning Silicone Co., Ltd.

Examples of nonionic surfactants include the following.
1) Alkyl allyl ether ethylene oxide adduct
_{2) HO- (C 2 H 4} O) n - (C 3 H 6 O) m - (C 2 H 4 O) a molecular weight in _{n -OH 500~10000, C 2 H 4} O content is 0 to 55%
3) Alkyl ester type:
R ₁ (R ₂ ) CHCOO (C ₂ H ₄ O) _n R ₁ , R ₂ : C1-C10 alkyl group n: 1-8
4) Acetylene diols and 0 to 8 mol adducts thereof of ethylene oxide As the antifoaming agent used in the present invention, silicons and nonionic surfactants are preferable among these, and nonionic properties having an HLB value of about 1 to 4 are particularly preferable. Surfactants are particularly preferred.

As the antifoaming agent, an alkylene oxide block copolymer which is a compound represented by the following general formula (VI) is preferable.
Formula (VI)
_{HO-L 1 - (B-} O) X - (A-O) Y - (B'-O) Z -L 2 -H
In general formula (VI), A represents an alkylene group having 2 or more carbon atoms. B and B ′ represent an alkylene group having 3 or more carbon atoms. X, Y, and Z are each an integer of 1 or more. L ₁ and L ₂ are each an alkylene oxide polymer block having a degree of polymerization of 0 or more, and the alkylene group may be one type or two or more types. However, the carbon number is A <B, A <B ′.
Examples of the alkylene oxide that is a structural unit of the compound represented by the general formula (VI) include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, cyclohexene oxide, epichlorohydrin, epibromohydrin, methyl glycidyl ether, and allyl glycidyl. Ether, phenyl glycidyl ether, etc. are mentioned. Two or more of these are used.

  Of these alkylene oxides, ethylene oxide, propylene oxide, butylene oxide, or styrene oxide is preferred.

  Further, the block copolymer represented by the general formula (VI) is characterized by a structure in which an alkylene oxide having a small molecular weight (carbon number) is sandwiched between alkylene oxides having a high molecular weight. By using such a copolymer, the ink has excellent antifoaming and antifoaming properties, does not adversely affect the physical properties and storage stability of the ink, and does not adversely affect the quality of the formed image and the image storage stability. I understood that.

  The alkylene oxide block copolymer represented by the general formula (VI) is obtained by subjecting an active hydrogen-containing material as described below as a starting material to addition (ring-opening) polymerization of the alkylene oxide.

  Examples of the active hydrogen-containing substance include dihydric alcohols such as ethylene glycol, propylene glycol, and 1,4-butanediol.

As a first step, these starting materials are reacted with an alkylene oxide compound in the presence of a base or acid catalyst to form a first polymer block, and then in the second step the product of the first step is the same. Or it reacts with the alkylene oxide compound different from a 1st process in presence of a different catalyst, and adds a 2nd polymerization block. A compound represented by the general formula (VI) can be produced by adding an alkylene oxide polymer block in the same process.
These reaction steps are generally carried out at high temperatures. In each step, different catalysts may be used, or the same catalyst may be used. Examples of suitable base catalysts include sodium or potassium hydroxide, sodium methoxide, sodium ethoxide and the like. Examples of suitable acid catalysts include boron trifluoride, ether boron trifluoride compounds such as diethyl ether boron trifluoride adduct, and triethyloxonium, boron tetrafluoride and the like.

  The catalyst residue can be removed by ion exchange resin or neutralization.

  The molecular weight of the alkylene oxide block copolymer is preferably 10,000 or less, and more preferably 8,000 or less. When the molecular weight exceeds 10,000, the solubility in ink is lowered, and the storage stability of the ink is adversely affected.

Among the block copolymers of alkylene oxide, ethylene oxide polymer part (EO) _Y represented by the following general formula (VII) is converted into propylene oxide polymer parts (PO) _X and (PO) _Z. It has been found that the structure sandwiched between the inks is further excellent in the antifoaming property, antifoaming property, and storage stability of the ink.
Formula (VII)
HO- (PO) _X- (EO) _Y- (PO) _Z- H
In the general formula (VII), P represents a propylene group (PO represents propylene oxide). E represents an ethylene group (EO represents ethylene oxide). X, Y, and Z are each an integer of 1 or more.

  The weight average molecular weight of the block copolymer represented by the general formula (VI) or the general formula (VII) is preferably 10,000 or less, and more preferably 8,000 or less. When the molecular weight exceeds 10,000, the solubility in ink is lowered, and the storage stability of the ink is adversely affected. The content of ethylene oxide is preferably 10 to 80% by mass, and more preferably 10 to 50% by mass. When the ethylene oxide content is too low, the solubility in the black ink composition is lowered, and the storage stability of the ink is adversely affected. When the ethylene oxide content is too high, the antifoaming performance and the antifoaming performance are poor.

The block copolymer includes the following as examples of combinations of alkylene oxides.
HO- (EO) _a- (PO) _b- (EO) _c- (PO) _d- (EO) _e -H
HO- (EO) _a- (PO) _b- (EO) _c- (PO) _d- (BO) _e -H
HO- (BO) _a- (PO) _b- (EO) _c- (PO) _d- (BO) _e -H
HO- (EO) _a- (PO) _b- (EO) _c- (BO) _d- (EO) _e -H
HO- (EO) _a- (PO) _b- (EO) _c- (BO) _d- (PO) _e -H
HO- (BO) _a- (PO) _b- (EO) _c- (BO) _d- (PO) _e -H
HO- (EO) _a- (BO) _b- (EO) _c- (BO) _d- (EO) _e -H
HO- (EO) _a- (BO) _b- (EO) _c- (BO) _d- (PO) _e -H
HO- (PO) _a- (BO) _b- (EO) _c- (BO) _d- (PO) _e -H
HO- (EO) _a- (BO) _b- (PO) _c- (BO) _d- (EO) _e -H
HO- (EO) _a- (BO) _b- (PO) _c- (BO) _d- (PO) _e -H
HO- (BO) _a- (PO) _b- (PO) _c- (BO) _d- (PO) _e -H
HO- (EO) _a- (PO) _b- (EO) _c- (PO) _d- (EO) _e -H
HO- (EO) _a- (PO) _b- (EO) _c- (PO) _d- (BO) _e -H
HO- (BO) _a- (PO) _b- (EO) _c- (PO) _d- (BO) _e -H
HO- (EO) _a- (PO) _b- (EO) _c- (BO) _d -H
HO- (PO) _a- (EO) _b- (BO) _c- (EO) _d -H
HO- (PO) _a- (EO) _b- (BO) _c- (PO) _d -H
HO- (BO) _a- (PO) _b- (EO) _c- (BO) _d -H
HO- (BO) _a- (EO) _b- (BO) _c- (EO) _d -H
HO- (BO) _a- (EO) _b- (BO) _c- (PO) _d -H
HO- (EO) _a- (BO) _b- (PO) _c- (BO) _d -H
HO- (BO) _a- (PO) _b- (BO) _c- (PO) _d -H
HO- (PO) _a- (EO) _b- (PO) _c -H
HO- (PO) _a- (EO) _b- (BO) _c -H
HO- (BO) _a- (EO) _b- (BO) _c -H
HO- (BO) _a- (PO) _b- (BO) _c -H
In the above, EO represents ethylene oxide, PO represents propylene oxide, and BO represents butylene oxide. The above-mentioned a, b, c, d, and e can be selected from numerical values within a preferable molecular weight range. The value of a + b + c + d + e is 30 to 200, preferably 40 to 150, and the molecular weight is 10,000 or less.

Specific examples are described below.
_{E-1: HO- (CH 3} CHCH 2 O) m - (CH 2 CH 2 O) n - (CH 3 CHCH 2 O) m '-H
m + n + m ′ = 60, n: 15
_{E-2: HO- (CH 3} CHCH 2 O) m - (CH 2 CH 2 O) n - (CH 2 CH (CH 3) O) m '-H
m + n + m ′ = 50, n: 25
_{E-3: HO- (CH 3} CHCH 2 O) m - (CH 2 CH 2 O) n - (CH 3 CHCH 2 O) m '-H
m + n + m ′ = 55, n: 15
_{E-4: HO- (CH 3} CHCH 2 O) m - (CH 2 CH 2 O) n - (CH 3 CHCH 2 CH 2 O) m '-H
m + n + m ′ = 71, n: 15
_{E-5: HO- (CH 3} CHCH 2 CH 2 O) m - (CH 2 CH 2 O) n - (CH 3 CHCH 2 CH 2 O) m '-H
m + n + m ′ = 140, n: 72
_{E-6: HO- (CH 3} CHCH 2 CH 2 O) m - (CH 2 CH 2 CH 2 O) n - (CH 3 CHCH 2 CH 2 O) m '-H
m + n + m ′ = 140, n: 80
_{E-7: HO- (CH 2} CH 2 O) n '- (CH 3 CHCH 2 O) m - (CH 2 CH 2 O) n - (CH 3 CHCH 2 O) m' - (CH 2 CH 2 O ) _{n ''} -H
m + m ′ = 50, n: 15, n ′ + n ″ = 20
The above-mentioned values such as n actually have a distribution width and are average values of the distribution.
Furthermore, specific examples of the block copolymer of ethylene oxide / propylene oxide represented by the general formula (VII) include Pluronic RPE 1720, RPE 1740, RPE 2035, RPE 2510, RPE 2520, RPE 2525, RPE manufactured by BASF. 3110, 10R5, 10R8, 12R8, 17R1, 17R2, 17R4, 17R8, 22R4, 25R1, 25R2, 25R4, 25R5, 25R8, 31R1, 31R2, 31R4 and the like.
These antifoaming agents may be used alone or in combination. The total amount added to the black ink composition is preferably 0.001 to 5 mass%, more preferably 0.005 to 3 mass%. If the amount added is too small, the antifoaming performance and defoaming performance of the black ink composition are inferior, and if it is too large, the solubility in the black ink composition is lowered and the storage stability of the ink is adversely affected. .

(Bronze improver)
The bronze improving agent used in the present invention has a function of weakening or eliminating the bronzing phenomenon seen when solid printing is performed using an ink set containing a black ink composition. For example, as a bronze improving agent, The aromatic compound which has a carboxyl group, or its salt is mentioned.
The aromatic compound having a carboxyl group or a salt thereof used in the present invention may be any aromatic compound or salt thereof having at least one carboxyl group in the molecular structure, but one carboxyl group. Are preferred, and those having a naphthalene skeleton are preferred. Those having an —OR group (R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) together with a carboxyl group in the naphthalene skeleton can also be preferably used. In the compound having a naphthalene skeleton or a salt thereof, One is preferred. Further, a compound having a carboxyl group at the 2-position and having a naphthalene skeleton or a salt thereof is more preferable, and a more preferable one is an alkali metal salt of a compound having a carboxyl group at the 2-position and having a naphthalene skeleton. . Of the alkali metal salts of compounds having a carboxyl group at the 2-position and having a naphthalene skeleton, lithium salts are not only particularly preferred from the viewpoint of improving bronzing resistance but also from the viewpoint of clogging resistance.

Specific examples of the aromatic compound having a carboxyl group or a salt thereof include 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, 1-naphthoic acid, 2-naphthoic acid, 3-hydroxy- 2-naphthoic acid, 6-hydroxy-2-naphthoic acid, 3-methoxy-2-naphthoic acid, 6-methoxy-2-naphthoic acid, 6-ethoxy-2-naphthoic acid, 6-propoxy-2-naphthoic acid, Examples thereof include 4-hydroxybenzoic acid, 2,6-naphthalenedicarboxylic acid, and salts thereof (particularly lithium salts), which can be used alone or in combination.
The salt of the aromatic compound having a carboxyl group is added in the form of a salt and can be contained in the black ink composition, and the aromatic compound having a carboxyl group and the base are added separately. It can also be contained in the black ink composition.

  The total content of the aromatic compound having a carboxyl group and / or a salt thereof is determined by the kind of the aromatic compound having a carboxyl group and / or a salt thereof, the kind of the dye, the kind of the solvent component, and the like.

Further, as another bronze improving agent, a colorless water-soluble planar compound having more than 10 delocalized π electrons in one molecule is preferable.
This water-soluble planar compound will be described. When the number of π electrons constituting a delocalized π electron system increases and the π electron system spreads, it often has absorption in the visible region. In the present invention, the term “colorless” includes a state in which the image is slightly colored within a range that does not affect the image. Further, although it may be a fluorescent compound, a compound having no fluorescence is preferable, and more preferably, λmax of the absorption peak on the longest side is 350 nm or less, more preferably 320 nm or less, and the molar extinction coefficient is 10,000 or less. It is a compound of this.
The water-soluble planar compound has more than 10 delocalized π electrons in one molecule. The upper limit of the number of π electrons is not particularly limited, but is preferably 80 or less, more preferably 50 or less, and particularly preferably 30 or less. Further, more than 10 π electrons may form one large delocalized system, but may form two or more delocalized systems. In particular, a compound having two or more aromatic rings in one molecule is preferable. The aromatic ring may be an aromatic hydrocarbon ring, an aromatic heterocycle containing a heteroatom, or a ring condensed to form one aromatic ring. Examples of the aromatic ring include benzene, naphthalene, anthracene, pyridine, pyrimidine, pyrazine, triazine and the like.

The water-soluble planar compound is preferably a compound that dissolves at least 1 g in 100 g of water at 20 ° C. More preferred is a compound that dissolves 5 g or more, and most preferred is a compound that dissolves 10 g or more.
In the case of a compound having two or more aromatic rings in one molecule, it is particularly desirable to have at least two solubilizing groups bonded to the aromatic rings in the molecule. Useful solubilizing groups include, but are not limited to, sulfo groups, carboxyl groups, hydroxy groups, phosphono groups, carbonamido groups, sulfonamido groups, quaternary ammonium salts and other groups apparent to those skilled in the art. . Of these, a sulfo group and a carboxyl group are preferable, and a sulfo group is most preferable.
Although the maximum number of solubilizing groups in a molecule is limited only by the number of available substituent positions, for practical purposes there are 10 identical or different solubilizing groups in the molecule. Is enough. There is no limitation on the counter cation of these soluble groups, and examples include alkali metals, ammonium, and organic cations (tetramethylammonium, guanidinium, pyridinium, etc.). Among them, alkali metals and ammonium are preferable, particularly lithium, sodium, Ammonium is preferred, and lithium and ammonium are most preferred.
Specific compounds include JP-A 63-55544, JP-A 3-146947, 3-149543, JP-A 2001-201831, 2002-139822, 2002-196460, Examples thereof include compounds described in JP-A Nos. 2002-244257, 2002-244259, 2002-296743, 2002-296744, and Japanese Patent Application No. 2002-17728.

Of these, compounds represented by the following general formula (VIII) are preferably used.
General formula (VIII):
A ₁₀ -X ₁₀ -L _10- (Y ₁₀ -B ₁₀ ) n
In the formula, A ₁₀ , L ₁₀ and B ₁₀ each independently represent an aromatic group (an aryl group or an aromatic heterocyclic group). X ₁₀ and Y ₁₀ each independently represent a divalent linking group. n represents 0 or 1. The aromatic group may be a single ring or a condensed ring. The divalent linking group represents an alkylene group, an alkenylene group, -CO-, -SOn- (n is 0, 1, 2), -NR- (R is a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. ), -O-, and a divalent group obtained by combining these linking groups. However, the compound represented by the general formula 1 contains at least one ionic hydrophilic group selected from a sulfo group, a carboxyl group, a phenolic hydroxyl group, and a phosphono group. These ionic hydrophilic groups may be in the form of salts, and there are no restrictions on the counter cation, and examples include alkali metals, ammonium, and organic cations (tetramethylammonium, guanidinium, pyridinium, etc.). Metal and ammonium are preferable, lithium, sodium and ammonium are particularly preferable, and lithium and ammonium are most preferable.

In addition, the compound represented by the general formula (VIII) may have a substituent other than the ionic hydrophilic group, and specific substituents include an alkyl group, an aryl group, an aralkyl group, a heterocyclic group, an alkoxy group. Group, aryloxy group, hydroxyl group, amino group (including anilino group and heterocyclic amino group), acyl group, acylamino group, ureido group, halogen atom, sulfamoyl group, carbamoyl group, sulfonamide group, sulfonyl group, sulfenyl group , A sulfinyl group and the like, and these may further have a substituent. Among the compounds of the general formula (VIII), n = 1 is preferable, and at least one of A ₁₀ , L ₁₀ and B ₁₀ is an aromatic heterocycle. Further, those containing 2 to 4 ionic hydrophilic groups are preferred.

  It is not clear from what action mechanism the water-soluble planar compound suppresses bronze, but the stronger π-electron interaction with the dye aggregated (associated) by the π-electron interaction between the dye molecules. It acts as a deflocculating agent that eliminates aggregation by acting, and as a result, it is considered that the bronze phenomenon is improved. The deaggregating agent must be flat and the π-electron system greatly spread in order to enter between the aggregating dyes or to develop a strong π-electron interaction with the dyes on the surface of the dye aggregate. is important. It is also important that the deflocculating agent has sufficient solubility so that the deflocculating agent itself or a complex formed by the dye and the deflocculating agent does not precipitate. The number of π electrons required varies depending on the size of the ink-jet dye used, but the dye used for ink-jet is a plane that is greatly expanded as represented by direct dyes to improve fixability. Since it has a structure, it is presumed that the deaggregating agent needs to be a colorless water-soluble planar compound having a spread of more than 10 delocalized π-electron systems in one molecule.

  Preferred examples of the compound used in the present invention include the aforementioned JP-A Nos. 2002-139822, 2002-196460, 2002-244257, 2002-244259, 2002-296743, and 002-296744. And compounds described in Japanese Patent Application Nos. 2002-17728 and publications. Representative compounds (deaggregating agents) are shown below.

  A preferred compound of the present invention can be easily synthesized with reference to the aforementioned JP-A No. 2002-139822.

  These bronze improvers are preferably in the range of 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, based on the total weight of the black ink composition.

(Ozone resistance improver)
The ozone resistance improver is a compound having a function of suppressing dye oxidation, and examples thereof include thiol compounds, amidine compounds, carbazide compounds, hydrazide compounds, and guanidine compounds.

(Thiol compounds)
The thiol compound used in the present invention is a compound having an SH group, preferably an aromatic thiol or an aliphatic thiol, and preferably a compound represented by the general formula (B).
Formula (B):
R ₁₀ -SH
(In the formula, R is an alkyl group, an aryl group, or a heterocyclic group.)
The above R _{10 will be} described.
As an alkyl group, Preferably it is C1-C12, More preferably, a C1-C6 thing is mentioned.
As an aryl group, Preferably it is C6-C18, More preferably, a C6-C10 thing is mentioned.
Heterocyclic groups include furyl, pyridyl, pyrimidyl, pyrrolyl, pyrrolinyl, pyrrolidyl, dioxolyl, pyrazolyl, pyrazolinyl, pyrazolidyl, imidazolyl, oxazolyl, thiazolyl, oxadiazolyl, triazolyl , Thiadiazolyl group, pyryl group, pyridyl group, piperidyl group, dioxanyl group, morpholyl group, pyridazyl group, pyrazyl group, piperazyl group, triazyl group, trithianyl group and the like.
The above substituents represented by R ₁₀ include those in which the hydrogen atom is further substituted with any other substituent as described above. Examples of such a substituent include a carboxyl group, an oxo group, an amino group, an amino acid residue (preferably 2 to 8 carbon atoms), an ammonium group, a hydroxyl group, a thiol group, and an alkoxy group (preferably 1 to 12 carbon atoms). ), An acylamino group (preferably having 1 to 12 carbon atoms, a carboxyl group, an amino group, etc. may be substituted), a carbamoyl group, etc., and two or more of these substituents are substituted with the same molecule. It may be.

As a method for synthesizing the compound represented by the general formula (B), for example, a thiol in which R is an aryl group is obtained by a reaction between the corresponding aryl Grignard reagent and elemental sulfur, and a corresponding alkyl halide and sulfide are obtained. Reaction of sodium hydride or thiourea gives a thiol in which R ₁₀ is an alkyl group.

(Amidine compounds)
The amidine compound used in the present invention means a compound having a structure in which —C (═NH) —NH ₂ group (amidino group) is bonded to a carbon atom of a carbon-containing group, and the above-mentioned —C (═NH) One or more hydrogen atoms of the —NH ₂ group may be substituted with a substituent.
As the amidine-based compound, a compound represented by the general formula (C) is preferable.

(In the formula, R ₂₁ , R ₂₂ , R ₂₃ , or R ₂₄ each independently represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, and when R ₂₁ contains a nitrogen atom, (It does not bind to C shown in the formula.)
As an alkyl group, Preferably it is C1-C12, More preferably, a C1-C6 thing is mentioned.
As an aryl group, Preferably it is C6-C18, More preferably, a C6-C10 thing is mentioned.
Heterocyclic groups include furyl, pyridyl, pyrimidyl, pyrrolyl, pyrrolinyl, pyrrolidyl, dioxolyl, pyrazolyl, pyrazolinyl, pyrazolidyl, imidazolyl, oxazolyl, thiazolyl, oxadiazolyl, triazolyl , Thiadiazolyl group, pyryl group, pyridyl group, piperidyl group, dioxanyl group, morpholyl group, pyridazyl group, pyrazyl group, piperazyl group, triazyl group, trithianyl group and the like.
In the substituents represented by R _{21 to} R ₂₄ , the hydrogen atom may be further substituted with any other substituent. Examples of such substituents include halogen atoms such as chlorine, nitro groups, amino groups, carboxyl groups, carbamoyl groups, amidino groups, and aryloxy groups (the aryl moiety may be further substituted by the substituents listed here). 2 or more of these substituents may be substituted with the same molecule. In the amino group, carbamoyl group, and amidino group, the hydrogen atom may be substituted with an alkyl group, aryl group, or heterocyclic group represented by R _{21 to} R ₂₄ .

  The amidine-based compound may be in the form of a salt such as hydrochloride.

  As a method for synthesizing the compound represented by the general formula (C), for example, the compound can be obtained through at least a step of causing ammonia to act on the hydrochloride of the corresponding imino ether.

(Carbazide compounds)
The carbazide-based compound used in the present invention means carbazide and derivatives thereof, and preferably has the general formula (D) R ₂₅ R ₂₆ NCONHNR ₂₇ R ₂₈ (R _{25 to} R ₂₈ each independently represents a hydrogen atom or an organic It is a compound represented by.
Examples of the organic group, those listed in the R ₂₁ to R ₂₄ are preferred.
The substituents represented by R _{25 to} R ₂₈ include those in which the hydrogen atom is further substituted with any other substituent. As such substituents, in addition to those exemplified as those that can be substituted with R _{21 to} R ₂₄ , —HNCONHNR ₂₉ R ₃₀ (wherein R ₂₉ and R ₃₀ are organic groups, and preferred examples thereof) Is the same as R _{21 to} R ₂₄ ). In the present invention, —HNCONHNR ₂₉ R ₃₀ is referred to as a carbazide structure. The carbazide compound used in the present invention preferably has two or more (more preferably 2 to 6) carbazide structures in the same molecule.

Specifically, the carbazide compound represented by the general formula (D) includes the corresponding isocyanate, diisocyanate, urea derivative and the like, NH ₂ NR ₂₇ R ₂₈ (R ₂₇ and R ₂₈ are as defined above). It can be obtained by a condensation reaction with hydrazine compounds represented by

(Hydrazide compounds)
The hydrazide-based compound used in the present invention means hydrazide and derivatives thereof, preferably the general formula (E) R ₃₁ CONHNR ₃₂ R ₃₃ (R _{31 to} R ₃₃ each independently represents a hydrogen atom, a hydrazino group, Or an organic group, or a ring formed by bonding with R ₃₁ and R ₃₂ or R ₃₃ .
Examples of the organic group, those listed in the R ₂₁ to R ₂₄ in the general formula (C) are preferred.
The substituents represented by R _{31 to} R ₃₃ include those in which the hydrogen atom is further substituted with any other substituent. Examples of such a substituent include, in addition to those exemplified as those that can be substituted with R _{21 to} R ₂₄ , an acyl group, a cyano group, an alkoxy group, an aralkyloxy group, a benzoyl group, —CONHNR ₃₄ R ₃₅ (wherein , R ₃₄ and R ₃₅ are organic groups, and preferred examples thereof are the same as those of R _{21 to} R _24. ). In the present invention, —CONHNR ₁₄ R _{15 is referred} to as a hydrazide structure. The hydrazide compound used in the present invention preferably has two or more (more preferably 2 to 6) hydrazide structures in the same molecule.

Specifically, the hydrazide compound represented by the general formula (E) includes a corresponding carboxylic acid ester, an acid derivative such as an acid halide, an acid anhydride, etc., and a general formula NH ₂ NR ₃₂ R ₃₃ ( R ₃₂ and R ₃₃ have the same meanings as described above) and are obtained by a condensation reaction with hydrazine compounds represented by the above.

Of the ozone resistance improvers, guanidine compounds are particularly preferable. Hereinafter, the guanidine compound will be described in detail.
(Guanidine compounds)
The guanidine compound used in the present invention means a compound having an N—C (═N) —N structure.
As the guanidine compound, a compound represented by the general formula (F) is preferable.

(Wherein R ₄₁ , R ₄₂ , R ₄₃ or R ₄₄ each independently represents a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a heterocyclic group or an amino group, and R ₄₅ represents a hydrogen atom or an alkyl group) A group, an alkoxy group, an aryl group, or a heterocyclic group, and these alkyl group, alkoxy group, aryl group, heterocyclic group, and amino group may be substituted or unsubstituted.)
As an alkyl group, Preferably it is C1-C12, Most preferably, a C1-C6 thing is mentioned.
As an alkoxy group, Preferably it is C1-C12, Most preferably, a C1-C6 thing is mentioned.
As an aryl group, Preferably it is C6-C18, Most preferably, a C6-C10 thing is mentioned.
Heterocyclic groups include furyl, pyridyl, pyrimidyl, pyrrolyl, pyrrolinyl, pyrrolidyl, dioxolyl, pyrazolyl, pyrazolinyl, pyrazolidyl, imidazolyl, oxazolyl, thiazolyl, oxadiazolyl, triazolyl , Thiadiazolyl group, pyryl group, pyridyl group, piperidyl group, dioxanyl group, morpholyl group, pyridazyl group, pyrazyl group, piperazyl group, triazyl group, trithianyl group and the like.
The alkyl group, alkoxy group, aryl group, or heterocyclic group represented by R _{41 to} R ₄₅ includes those in which the hydrogen atom is further substituted with any other substituent. Examples of such substituents include halogen atoms such as chlorine, nitro groups, amino groups, carboxyl groups, hydroxyl groups, carbamoyl groups, amidino groups, guanidino groups, aryloxy groups (the aryl moiety depends on the substituents listed here). Further, two or more of these substituents may be substituted with the same molecule. In the amino group, carbamoyl group, amidino group, and guanidino group, the hydrogen atom may be substituted with an alkyl group, alkoxy group, aryl group, or heterocyclic group represented by R _{41 to} R ₄₅ .
In the amino group represented by R _{41 to} R ₄₄ , the hydrogen atom may be substituted with an alkyl group, an alkoxy group, an aryl group, a heterocyclic group, or the like represented by the above R _{41 to} R ₄₅ .

  The guanidine-based compound may be in the form of a salt or a metal complex. For example, hydrochloride, nitrate, phosphate, sulfamate, carbonate, acetate and the like can be mentioned.

  As a method for synthesizing the compound represented by the general formula (F), for example, it can be obtained through at least a step of causing ammonia to act on the hydrochloride of the corresponding imino ether.

  The guanidine-based compound may be a polymer having an N—C (═N) —N structure. Examples of such a polymer include, but are not limited to, compounds containing a repeating unit represented by the following general formula (Fa), general formula (Fb), and general formula (Fc). Is not to be done. The compound containing the repeating unit may be an oligomer. A monomer may be sufficient as the compound containing the repeating unit represented by general formula (Fc). Further, these compounds are preferably salts with acids.

In general formula (Fa), R ₄₅ has the same meaning as described above, R ₄₆ represents any of R ₄₁ , R ₄₂ , R ₄₃ , or R ₄₄ , and n R ₄₅ and R ₄₆ may be the same May be different. n is an integer greater than or equal to 2, Preferably it is 2-30, More preferably, it is 2-15. The compound containing the repeating unit represented by the general formula (Fa) may be a homopolymer or a copolymer with another repeating unit such as azetidinium. Moreover, although a terminal structure can be selected suitably, a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a heterocyclic group, or an amino group is preferable.

In the general formula (Fb), R ₄₅ and R ₄₆ have the same meaning as described above, and one R ₄₅ and R ₄₆ may be the same or different. l is an integer greater than or equal to 2, Preferably it is 2-10, More preferably, it is 2-5. m is an integer greater than or equal to 1, Preferably it is 1-6, More preferably, it is 1-3. The compound containing the repeating unit represented by formula (Fb) may be a homopolymer or a copolymer with another repeating unit such as azetidinium. Moreover, although a terminal structure can be selected suitably, a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a heterocyclic group, or an amino group is preferable.

In the general formula (Fc), R ₄₅ has the same meaning as described above, R ₄₇ has the same meaning as R ₄₁ or R ₄₂ , R ₄₈ has the same meaning as R ₄₃ or R ₄₄ , p R ₄₅ , R ₄₇ and R ₄₈ may be the same or different. p is an integer greater than or equal to 1, Preferably it is 1-10, More preferably, it is 1-5. The compound containing the repeating unit represented by formula (Fc) may be a homopolymer or a copolymer with another repeating unit such as azetidinium. Moreover, although a terminal structure can be selected suitably, a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a heterocyclic group, or an amino group is preferable.

  As the ozone resistance improver, the above various compounds can be used alone or in combination, and the total amount used is preferably 0.1 to 10% by mass in the black ink composition.

(Chelating agent)
A chelating agent refers to a compound capable of forming a metal ion complex having two or more donor atoms in a molecule bonded to a metal ion. The chelating agent has a function of suppressing head damage caused by heavy metals, particularly under high humidity conditions, and can maintain the ejection property of inkjet recording favorably.
Various compounds are known as such chelating agents.
For example, aliphatic or aromatic carboxylic acid, dicarboxylic acid, polycarboxylic acid more than tricarboxylic acid, oxycarboxylic acid, ketocarboxylic acid, thiocarboxylic acid, aromatic aldehyde, amine compound, diamine compound, polyamine compound, aminopolycarboxylic acid , Nitrilotriacetic acid derivatives, ethylenediamine polycarboxylic acid, amino acids, heterocyclic carboxylic acids, heterocyclics, pyrimidines, nucleosides, purine bases, β-diketones, oxins, etc., which can be used alone or in combination be able to. Among these, ethylenediamine polycarboxylic acids or chelating agents in which a loan pair of nitrogen atoms can act as a donor are particularly preferable.

  Examples of such include, but are not limited to, pyridine-2-carboponic acid, pyridine-2,3-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, iminodiacetic acid <IDA >, Iminodipropionic acid, N-methyliminodiacetic acid, N, N′-ethylenediaminediacetic acid <EDDA>, ethylenediaminetetraacetic acid <EDTA>, ethylenediamine-N, N′-diacetic acid-N, N′-dipropionic acid < EDPA>, ethylenediaminetetrapropionic acid <EDTP>, 1,2-propylenediaminetetraacetic acid <PDTA>, trimethylenediaminetetraacetic acid <THTA>, tetramethylenediaminetetraacetic acid, pentamethylenediaminetetraacetic acid, hexamethylenediaminetetraacetic acid, Octamethylenediaminetetraacetic acid, 1,2-cyclopentanediamine Traacetic acid, trans-cyclohexane-1,2-diaminetetraacetic acid <CDTA>, 1,3,5-triaminocyclohexanehexaacetic acid <CTHA>, ethyl etherdiaminetetraacetic acid [2,2-oxybis (ethyliminodiacetic acid)] E-EDTA>, diethylenetriaminepentaacetic acid <DTPA>, glycol etherdiaminetetraacetic acid <GEDTA>, trimethylenetetraaminehexaacetic acid <TTHA>, quinoline-2-carboxylic acid, quinoline-8-carboxylic acid, 8-hydroxycinoline 1,10-phenanthroline, 2-methyl-1,10-phenanthroline <70>, 5-methyl-1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 4,7-dimethyl-1, 10-phenanthroline etc. are mentioned.

  In the present invention, the amount of the chelating agent added to the black ink composition is preferably 0.01 to 100 mol times, more preferably 0.05 to 50 mol times, and particularly preferably 0.1 to 10 mol times with respect to the dye.

(Anti-drying agent (wetting agent), penetration enhancer)
Examples thereof include those described in the section of the water-miscible organic solvent.

(UV absorber)
Examples of the ultraviolet absorber used for improving the storability of the image in the present invention are JP-A Nos. 58-185677, 61-190537, JP-A-2-782, and JP-A-5-97075. Benzotriazole compounds described in JP-A-9-34057, etc., benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194443, US Pat. No. 3,214,463, etc. Cinnamic acid compounds described in JP-A-48-30492, JP-A-56-21141, JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368. And triazine compounds described in JP-A-10-182621, JP-A-8-501291, etc. Jar No. Compounds described in No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene-based compounds and benzoxazole-based compounds, so-called fluorescent brighteners, can also be used.
The ultraviolet absorber can be used in an amount of 0.05 to 10% by mass with respect to the black ink composition.

(Antioxidant)
In the present invention, various organic and metal complex anti-fading agents can be used as the antioxidant used to improve image storage stability. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like. More specifically, Research Disclosure No. No. 17643, No. VII, I to J, ibid. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of the representative compounds described in pages 127 to 137 of JP-A-62-215272 can be used.
The antioxidant can be used in an amount of 0.05 to 10% by mass with respect to the black ink composition.

(Viscosity modifier)
The viscosity modifier has a function of adjusting the viscosity, and examples thereof include the water-miscible organic solvent. Examples include glycerin, diethylene glycol, triethanolamine, 2-pyrrolidone, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether.
Other than water-miscible organic solvents, for example, water-soluble polymers such as celluloses and polyvinyl alcohol, nonionic surfactants, and the like can be mentioned. More specifically, “Viscosity Adjustment Technology” (Technical Information Association, 1999), Chapter 9, and “Chemicals for Inkjet Printers (98 Supplement) —Material Development Trends and Prospects Survey” (CMC, 1997) 162- Page 174.

  In the present invention, it is also possible to contain a high molecular weight compound as a viscosity modifier. Here, the high molecular weight compound means all high molecular compounds having a number average molecular weight of 5000 or more contained in the black ink composition. These polymer compounds are soluble in water-soluble polymer compounds that are substantially soluble in aqueous media, water-dispersible polymer compounds such as polymer latex and polymer emulsion, and polyhydric alcohols that are used as auxiliary solvents. Alcohol-soluble polymer compounds and the like can be mentioned, but any compound that substantially dissolves or disperses uniformly in the ink liquid is included in the high molecular weight compound in the present invention.

Specific examples of the water-soluble polymer compound include polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, polyethylene oxide, water-soluble polymers such as polyoxyalkylene oxide such as polypropylene oxide, polysaccharides, starch, cationized starch, casein, natural water-soluble polymers such as gelatin, polyacrylic acid, polyacrylamide or aqueous acrylic resins such as a copolymer thereof, aqueous alkyd resins, -SO in the molecule ₃ ^-, Examples thereof include water-soluble polymer compounds having a —COO 2 ^— group and substantially soluble in an aqueous medium.
Examples of the polymer latex include styrene-butadiene latex, styrene-acrylic latex, and polyurethane latex. Furthermore, an acrylic emulsion etc. are mentioned as a polymer emulsion.
These water-soluble polymer compounds can be used alone or in combination of two or more.

The water-soluble polymer compound is used to adjust the viscosity of the black ink composition in a viscosity region having good ejection characteristics. However, if the amount of the water-soluble polymer compound added is large, the viscosity of the black ink composition increases and The ejection stability is lowered, and the nozzle becomes clogged easily by the precipitate when the black ink composition elapses.
The addition amount of the polymer compound of the viscosity modifier depends on the molecular weight of the compound to be added (the higher the molecular weight, the smaller the addition amount may be), but the addition amount is 0 to 5 mass with respect to the total amount of the black ink composition. %, Preferably 0 to 3% by mass, more preferably 0 to 1% by mass.

(Dispersant)
Examples of the dispersant include cation, anion, nonionic and betaine surfactants, and specifically those described in the above-mentioned surfactant section.

(anti-rust)
Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and benzotriazole. These are preferably used in the black ink composition in an amount of 0.02 to 5.00% by mass.

(PH adjuster)
The pH adjusting agent used in the present invention may have functions such as imparting dispersion stability in addition to pH adjustment.
Examples of the pH adjuster include basic organic bases and inorganic alkalis, and acidic ones such as organic acids and inorganic acids.
Basic compounds include inorganic compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium acetate, potassium acetate, sodium phosphate, sodium hydrogen phosphate, aqueous ammonia, Use organic bases such as methylamine, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, piperidine, diazabicyclooctane, diazabicycloundecene, pyridine, quinoline, picoline, lutidine, collidine Is also possible.
Examples of acidic compounds include inorganic compounds such as hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, sodium hydrogen sulfate, potassium hydrogen sulfate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, acetic acid, tartaric acid, benzoic acid, trifluoroacetic acid. Organic compounds such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, saccharic acid, phthalic acid, picolinic acid and quinolinic acid can also be used.

The non-volatile component in the black ink composition of the present invention is 10 to 70% by mass of the total amount of the black ink composition. Ink ejection stability, print image quality, various image fastnesses, and bleeding of the image after printing In view of reducing stickiness on the printing surface, it is preferably 20 to 60% by mass, more preferably in terms of ejection stability of the black ink composition and reduction of image blur after printing.
Here, the non-volatile component means a liquid, a solid component or a high molecular weight component having a boiling point of 150 ° C. or higher under 1 atm. Non-volatile components of ink-jet ink are dyes, high boiling point solvents, polymer latex added as necessary, surfactants, dye stabilizers, antifungal agents, buffering agents, etc., and many of these non-volatile components are Other than the dye stabilizer, the dispersion stability of the black ink composition is lowered, and since it remains on the image receiving paper after printing, the stability due to the association of the dye on the image receiving paper is inhibited, and various fastnesses of the image area and It has the property of exacerbating image bleeding under high humidity conditions.

  The black ink composition of the present invention preferably has a viscosity of 1 to 20 mPa · s. More preferably, it is 2-15 mPa * s, Most preferably, it is 2-10 mPa * s. If it exceeds 20 mPa · s, the fixing speed of the recorded image becomes slow, and the discharge performance also deteriorates. If it is less than 1 mPa · s, the recorded image is blurred and the quality is lowered. This viscosity is measured at 25 ° C. The viscosity is adjusted by the viscosity modifier. In the case of inkjet recording, the addition amount of the water-miscible organic solvent is preferably used in the range of 5 to 70% by mass and more preferably in the range of 10 to 60% by mass with respect to the black ink composition. preferable. Two or more water-miscible organic solvents can be used in combination.

  The method for measuring the viscosity of the liquid is described in detail in JIS Z8803, but can be easily measured with a commercially available viscometer. For example, the rotary type includes Tokyo Keiki B-type viscometer and E-type viscometer. In this invention, it measured at 25 degreeC by the vibration type VM-100AL type of Yamaichi Electric.

The black ink composition of the present invention preferably has a surface tension of 20 to 50 mN / m, and more preferably 20 to 40 mN / m.
This surface tension means both dynamic surface tension and static surface tension, both of which are measured at 25 ° C. When the surface tension exceeds 50 mN / m, the discharge stability, the bleeding at the time of color mixing, the print quality such as the whiskers are remarkably lowered. Further, when the surface tension of the ink is set to 20 mN / m or less, there may be a case where printing failure occurs due to adhesion of ink to the hard surface during ejection. The surface tension can be adjusted by using a surfactant or the like, and those listed in the above-mentioned surfactant section can be used.

As a static surface tension measuring method, a capillary rising method, a dropping method, a hanging ring method and the like are known. In the present invention, a vertical plate method is used as a static surface tension measuring method.
When a thin plate of glass or platinum is partially immersed in the liquid and suspended vertically, the surface tension of the liquid acts downward along the length of contact between the liquid and the plate. The surface tension can be measured by balancing this force with an upward force.

  Examples of the dynamic surface tension measurement method include “New Experimental Chemistry Course, Vol. 18, Interface and Colloid” [Maruzen Co., Ltd., p. 69-90 (1977)], the vibration jet method, the meniscus dropping method, the maximum bubble pressure method and the like are known, and further, the liquid film breakage as described in JP-A-3-2064 is known. In the present invention, a bubble pressure differential pressure method is used as a dynamic surface tension measurement method. The measurement principle and method will be described below.

  When bubbles are generated in the solution that has become homogeneous by stirring, a new gas-liquid interface is generated, and the surfactant molecules in the solution gather on the surface of the water at a constant rate. When the bubble rate (bubble generation rate) is changed, if the generation rate slows down, more surfactant molecules gather on the surface of the bubble, so the maximum bubble pressure just before the bubble pops is reduced, The maximum bubble pressure (surface tension) relative to the bubble rate can be detected. As a preferable dynamic surface tension measurement, a method is used in which bubbles are generated in a solution using two large and small probes, the differential pressure in the maximum bubble pressure state of the two probes is measured, and the dynamic surface tension is calculated. Can be mentioned.

The black ink composition of the present invention preferably has a conductivity of 0.01 to 10 S / m, and a preferable range is 0.05 to 5 S / m. This conductivity is measured at 25 ° C. By keeping the conductivity in the above range, image storage stability is ensured.
The conductivity can be measured by an electrode method using commercially available saturated potassium chloride.
The conductivity can be controlled mainly by the ion concentration in the aqueous solution. When the salt concentration is high, desalting can be performed using an ultrafiltration membrane or the like. Moreover, when adjusting conductivity by adding salt etc., it can adjust by adding various organic substance salt and inorganic substance salt.
Inorganic salts include potassium halide, sodium halide, sodium sulfate, potassium sulfate, sodium hydrogen sulfate, potassium hydrogen sulfate, sodium nitrate, potassium nitrate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium phosphate, sodium monohydrogen phosphate, Inorganic compounds such as boric acid, potassium dihydrogen phosphate, sodium dihydrogen phosphate, sodium acetate, potassium acetate, potassium tartrate, sodium tartrate, sodium benzoate, potassium benzoate, sodium p-toluenesulfonate, potassium saccharinate Organic compounds such as potassium phthalate and sodium picolinate can also be used.
The conductivity can also be adjusted by selecting the additive.

The black ink composition of the present invention preferably has a pH of 7 to 9, more preferably 7 to 8. When the pH is less than 7, the solubility of the dye is lowered and the nozzle is easily clogged, and when it exceeds 9, the water resistance tends to deteriorate. As a pH measurement method, a commercially available test paper can be used, and measurement by an electrode method using saturated potassium chloride is also possible.
The pH of the black ink composition is adjusted by using the pH adjusting agent.

  The black ink composition of the present invention can be used for various image recording because of its high image durability. The dye for imaging can be used, for example, in photographic photosensitive materials, in thermal transfer materials, in thermal and pressure sensitive recording materials, in ink jet recording, etc. Is suitable for use as a black ink composition for inkjet recording.

  The method for preparing the black ink composition is described in detail in JP-A-5-295212, JP-A-7-97541, and JP-A-7-82515 in addition to the above-mentioned patent documents. It can also be used to prepare ink compositions.

  In addition to the short wave dye S and the long wave dye L of the present invention, other dyes may be used in combination with the black ink composition of the present invention. When other dyes are used in combination, the total amount of other dyes is preferably 0.1 to 30 parts by mass, and 0.2 to 20 parts by mass in 100 parts by mass of all the dyes. It is more preferable to contain, and it is still more preferable to contain 0.5-15 mass parts.

  The black ink composition of the present invention can be used not only for forming a single color image but also for forming a full color image. In order to form a full-color image, in addition to the black ink composition of the present invention, a magenta color ink, a cyan color ink, and a yellow color ink can be used, and two-color inks can be used for each color. Furthermore, an intermediate tone ink such as blue or orange can be used.

  Any dye can be used as the dye that can be used in the ink set of the present invention. For example, the dyes described in paragraphs 0090 to 0092 of JP-A No. 2003-306623 can be used.

[Inkjet recording method]
In the ink jet recording method of the present invention, energy is supplied to the ink for ink jet recording, and a known image receiving material, that is, plain paper, resin-coated paper, such as JP-A-8-169172, JP-A-8-27693, JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783, JP-A-10-153989, JP-A-10-217473, JP-A-10-235995 10-337947, 10-217597, 10-337947, etc. Form images on inkjet paper, film, electrophotographic co-paper, fabric, glass, metal, ceramics, etc. To do. As the image receiving material, an image receiving material having an ink receiving layer containing white inorganic pigment particles on a support is preferable. The description of paragraph numbers 0093 to 0105 of JP-A No. 2003-306623 can be applied as the ink jet recording method of the present invention.

  In forming an image, a polymer latex compound may be used in combination for the purpose of imparting glossiness or water resistance or improving weather resistance. The timing of applying the latex compound to the image receiving material may be before, after, or simultaneously with the application of the colorant, and therefore the addition location may be in the image receiving paper. It may be in ink or may be used as a liquid material of polymer latex alone. Specifically, JP 2002-166638, JP 2002-121440, JP 2002-154201, JP 2002-144696, JP 2002-080759, JP 2002-187342, and Japanese Patent Application 2002. The method described in 172774 can be used preferably.

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

The black ink composition or ink set of the present invention is not limited to an ink jet recording system, and uses a known system, for example, a charge control system that discharges ink using electrostatic attraction, and a vibration pressure of a piezo element. Drop-on-demand method (pressure pulse method), acoustic signal converted into acoustic beam, irradiating ink, acoustic ink jet method that ejects ink using radiation pressure, and heating ink to form bubbles Used for thermal ink jet system using pressure.
Inkjet recording methods use a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving the image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method is included.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.

Example 1
After adding ultrapure water (resistance value of 18 MΩ or more) to the following components to make 1 liter, the mixture was stirred for 1 hour while heating at 30 to 40 ° C. Thereafter, the ink liquid of each color was prepared by filtering under reduced pressure through a microfilter having an average pore diameter of 0.25 μm.
[Light cyan ink formulation]
(Solid content)
Cyan dye (C-1) 20 g / l
Urea (UR) 15g / l
Benzotriazole (BTZ) 0.08 g / l
PROXEL XL2 (PXL) (Avecia) 3.5g / l
(Liquid component)
Triethylene glycol (TEG) 110g / l
Glycerin (GR) 130g / l
Triethylene glycol monobutyl ether (TGB) 110 g / l
2-pyrrolidone (PRD) 60 g / l
Triethanolamine (TEA) 7g / l
Surfynol STG (SW) (Air Products) 10g / l

Cyan dye (C-1):

[Cyan ink prescription]
(Solid content)
Cyan dye (C-1) 60 g / l
Urea (UR) 30g / l
Benzotriazole (BTZ) 0.08 g / l
PROXEL XL2 (PXL) (Avecia) 3.5g / l
(Liquid component)
Triethylene glycol (TEG) 110g / l
Glycerin (GR) 130g / l
Triethylene glycol monobutyl ether (TGB) 130g / l
2-pyrrolidone (PRD) 60 g / l
Triethanolamine (TEA) 7g / l
Surfynol STG (SW) (Air Products) 10g / l

[Light magenta ink prescription]
(Solid content)
Magenta dye (M-1) 7.5 g / l
Urea (UR) 10g / l
PROXEL XL2 (PXL) (Avecia) 5g / l
(Liquid component)
Diethylene glycol (DEG) 90g / l
Glycerin (GR) 70g / l
Triethylene glycol monobutyl ether (TGB) 70 g / l
Triethanolamine (TEA) 6.9 g / l
Surfynol STG (SW) (Air Products) 10g / l

Magenta dye (M-1):

[Magenta ink prescription]
(Solid content)
Magenta dye (M-1) 23 g / l
Urea (UR) 15g / l
PROXEL XL2 (PXL) (Avecia) 5g / l
(Liquid component)
Diethylene glycol 90g / l
Glycerin 70g / l
Triethylene glycol monobutyl ether (TGB) 70 g / l
Triethanolamine 6.9g / l
Surfynol STG 10g / l

[Yellow ink prescription]
(Solid content)
Yellow dye (Y-1) 35g / l
PROXEL XL2 (PXL) (Avecia) 3.5g / l
Benzotriazole (BTZ) 0.08 g / l
Urea 10g / l
(Liquid component)
Triethylene glycol monobutyl ether (TGB) 130g / l
Glycerin (GR) 115g / l
Diethylene glycol (DEG) 120g / l
2-pyrrolidone 35g / l
Triethanolamine (TEA) 8g / l
Surfynol STG (SW) (Air Products) 10g / l

Yellow dye (Y-1):

[Dark yellow ink prescription]
(Solid content)
Yellow dye (Y-1) 35g / l
Magenta dye (M-1) 2g / l
Cyan dye (C-1) 2g / l
PROXEL XL2 (PXL) (Avecia) 5g / l
Benzotriazole (BTZ) 0.08 g / l
Urea 10g / l
(Liquid component)
Triethylene glycol monobutyl ether (TGB) 140 g / l
Glycerin (GR) 125g / l
Diethylene glycol (DEG) 120g / l
2-pyrrolidone 35g / l
Triethanolamine (TEA) 8g / l
Surfynol STG (SW) (Air Products) 10g / l

[Black ink prescription]
(Solid content)
Long wave dye L (Li salt of compound example 1-19 of long wave dye L) 60 g / l
Shortwave dye S 15g / l
(Na salt of Compound Example 2 of short wave dye S: CI Direct Red 84)
PROXEL XL2 (PXL) (Avecia) 5g / l
Urea 20g / l
Benzotriazole 3g / l
(Liquid component)
Diethylene glycol monobutyl ether (DGB) 100g / l
Glycerin (GR) 125g / l
Diethylene glycol (DEG) 100g / l
2-pyrrolidone 100g / l
Triethanolamine (TEA) 30g / l
Surfynol STG (Air Products) (SW) 10g / l

  An ink set composed of these inks was designated as IS-101. In each ink of this ink set, except that the short wave dye S of this black ink is changed to the short wave dye S (the counter cation is Na salt) in the table below, and the ink liquid changed to the following comparative dye is changed as shown in the table below. Respectively produced ink sets IS-102 to 110 made of the same ink. Table 3 lists the viscosity and surface tension of the black ink.

  Structure of comparative shortwave dye S

The inks of these ink sets were loaded into an ink cartridge of an ink printer PM-980C manufactured by EPSON, and an image pattern having a density change stepwise in black and white mode was printed so as to form a gray image.
As the image-receiving sheet used here, Fuji Photo Film Co., Ltd. inkjet paper photo glossy paper “Image Aya” was used.

1) Hue evaluation is a gray staircase pattern in which the color tone of gray at each print density is visually determined. A color tone that exhibits a preferable gray color tone at each density is indicated by A. B, the gray balance of which was lost at most densities was designated C.

2) About the image preservation | save property of black pigment | dye, the following evaluation was performed using the gray printing sample. Image preservation is evaluated by measuring the density of the staircase pattern using an X-rite 310 densitometer equipped with a status A filter, and using the point near Dvis = 1.0 as the reference point, the density change there It was performed by measuring.

2-1) For light fastness, after measuring the density (D _B , D _G , D _R ) Ci immediately after printing, 10 xenon light (85,000 lux) was applied to the image using a weather meter manufactured by Atlas. Sun exposure. Thereafter, the concentration Cf was measured again, and the dye residual ratio Cf / Ci × 100 was determined and evaluated.
The case where the dye afterimage ratio is 80% or more in all of D _B , D _G and D _R is A, the case where it is 70-80% at least partly is B, and the case where it is less than 70% is partly C .
2-2) For ozone resistance, the sample is left in a box where the ozone gas concentration is set to 10 ppm for 20 hours, and the concentration of pattern S before and after being left under ozone gas is measured with X-rite 310. Was evaluated.
The ozone gas concentration in the box was set using an ozone gas monitor (model: OZG-EM-01) manufactured by APPLICS.
The case where the dye afterimage ratio is 80% or more in all of D _B , D _G and D _R is A, the case where it is 70-80% at least partly is B, and the case where it is less than 70% is partly C .

3) With respect to image bleeding under high humidity in black ink, the image bleeding after storage for 72 hours at 25 ° C. and 90% RH was visually determined using a character print sample.
The case where no bleeding was observed was designated as A, the case where the hue of the color correction dye was slightly recognized around the character was designated as B, and the case where the color correction dye was clearly seen around the character was designated as C.

  The results are shown below.

  From the above results, it is clear that the ink liquid of the present invention is excellent in terms of hue, fastness, and image bleeding.

(Example 2)
Ink sets IS-201 to 210 containing black ink were prepared in the same manner as in Example 1 except that the short wave dye S and the long wave dye L used in the preparation of the black ink in Example 1 were changed to the dyes shown in Table 5. Prepared. Table 5 lists the viscosity and surface tension of the black ink.

  Table 6 shows the results of the same evaluation as in Example 1.

  As shown in the above table, it was shown that the ink liquid of the present invention was excellent in terms of hue, fastness, and image bleeding.

Example 3
After adding ultrapure water having a resistance value of 18 MΩ or more to the following components to make 1 liter, the mixture was stirred for 1 hour while being heated at 30 to 40 ° C. After that, each color ink was prepared by filtration under reduced pressure through a microfilter having an average pore size of 0.25 μm.
[Light cyan ink formulation]
(Solid content)
Cyan dye (C-1) 10 g / l
Urea (UR) 15g / l
Benzotriazole (BTZ) 0.08 g / l
PROXEL XL2 (PXL) (Avecia) 3.5g / l
(Liquid component)
Triethylene glycol (TEG) 50g / l
Glycerin (GR) 100g / l
Triethylene glycol monobutyl ether (TGB) 60g / l
1,5-pentanediol (PTD) 40 g / l
Isopropanol (IPA) 20g / l
Triethanolamine (TEA) 7g / l
Surfynol STG (SW) (Air Products) 10g / l

[Cyan ink prescription]
(Solid content)
Cyan dye (C-1) 30 g / l
Urea (UR) 40g / l
Benzotriazole (BTZ) 0.08 g / l
PROXEL XL2 (PXL) (Avecia) 3.5g / l
(Liquid component)
Triethylene glycol (TEG) 40g / l
Glycerin (GR) 100g / l
Triethylene glycol monobutyl ether (TGB) 70 g / l
1,5-pentanediol (PTD) 50 g / l
Isopropanol (IPA) 20g / l
Triethanolamine (TEA) 7g / l
Surfynol STG (SW) (Air Products) 10g / l

[Light magenta ink prescription]
(Solid content)
Magenta dye (M-1) 7.5 g / l
Urea (UR) 10g / l
PROXEL XL2 (PXL) (Avecia) 5g / l
(Liquid component)
Triethylene glycol (TEG) 40g / l
Glycerin (GR) 100g / l
Triethylene glycol monobutyl ether (TGB) 60g / l
1,5-pentanediol (PTD) 40 g / l
Isopropanol (IPA) 20g / l
Triethanolamine (TEA) 6.9 g / l
Surfynol STG (SW) (Air Products) 10g / l

[Magenta ink prescription]
(Solid content)
Magenta dye (M-1) 23 g / l
Urea (UR) 15g / l
PROXEL XL2 (PXL) (Avecia) 5g / l
(Liquid component)
Triethylene glycol (TEG) 50g / l
Glycerin (GR) 100g / l
Triethylene glycol monobutyl ether (TGB) 50g / l
1,5-pentanediol (PTD) 40 g / l
Isopropanol (IPA) 20g / l
Triethanolamine 6.9g / l
Surfynol STG 10g / l

[Yellow ink prescription]
(Solid content)
Yellow dye (Y-1) 35g / l
PROXEL XL2 (PXL) (Avecia) 3.5g / l
Benzotriazole (BTZ) 0.08 g / l
Urea 10g / l
(Liquid component)
Triethylene glycol (TEG) 40g / l
Glycerin (GR) 100g / l
Triethylene glycol monobutyl ether (TGB) 70 g / l
1,5-pentanediol (PTD) 60 g / l
Isopropanol (IPA) 20g / l
Triethanolamine (TEA) 8g / l
Surfynol STG (SW) (Air Products) 10g / l

[Black ink prescription]
(Solid content)
Long wave dye L (1-19 Na salt) 60 g / l
Shortwave dye S 15g / l
(Na salt of Compound Example 2 of short wave dye S: CI Direct Red 84)
PROXEL XL2 (PXL) (Avecia) 5g / l
Urea 20g / l
Benzotriazole 3g / l
(Liquid component)
Triethylene glycol (TEG) 80g / l
Glycerin (GR) 120g / l
Triethylene glycol monobutyl ether (TGB) 70 g / l
1,5-pentanediol (PTD) 60 g / l
Isopropanol (IPA) 20g / l
Triethanolamine (TEA) 8g / l
Surfynol STG (SW) (Air Products) 10g / l
An ink set composed of these inks was designated as IS-301. Ink sets IS-302 to 310 were made of the same inks except that the short wave dye S of the black ink was changed as shown in the following table for each ink of the ink set. Table 7 lists the viscosity and surface tension of the black ink.

The inks of these ink sets were loaded into the ink cartridges of an inkjet printer PIXUS990i manufactured by CANON, and an image pattern having a density changed stepwise in black and white mode was printed so as to form a gray image.
As the image-receiving sheet used here, Fuji Photo Film Co., Ltd. inkjet paper photo glossy paper “Image Aya” was used.
The hue and image fastness were also evaluated in the same manner as in Example 1.

  The results are shown below.

  From the above results, it is clear that the ink liquid of the present invention is excellent in terms of hue, fastness, and image bleeding.

Claims (20)

  A black ink composition comprising a water-soluble long wave dye L and a water-soluble short wave dye S having three or more azo groups in one molecule and having a naphthalene skeleton.   2. The black ink composition according to claim 1, wherein the water-soluble short wave dye S is used as a complementary color dye of the water-soluble long wave dye L. 3.   3. The black ink composition according to claim 1, wherein the water-soluble shortwave dye S is contained in an amount of 0.1 to 4% by mass.   4. The black ink composition according to claim 1, wherein the water-soluble long wave dye L is an azo dye having a naphthalene skeleton.   5. The black ink composition according to claim 1, wherein the water-soluble short wave dye S has a structure having 3 to 6 azo groups in one molecule. 6. The black ink composition according to claim 1, wherein the water-soluble long wave dye L has 2 to 4 conjugated azo groups in one molecule.   The black ink composition according to claim 1, wherein the water-soluble long wave dye L has a hydroxyl group at a conjugate position of an azo group.   The black ink composition according to claim 1, wherein the water-soluble long wave dye L has 1 or less heterocyclic ring in the chromophore.   The black ink composition according to claim 1, wherein the water-soluble long wave dye L has association properties.   The black ink composition according to claim 1, comprising a water-miscible organic solvent.   The black ink composition according to claim 10, wherein the water-miscible organic solvent has a vapor pressure of 2000 Pa or less.   12. The black according to claim 10, wherein the water-miscible organic solvent is at least one selected from the group consisting of an alcohol compound, a heterocycle-containing organic solvent, and an alkyl ether of a polyhydric alcohol. Ink composition.   One or more water-miscible organics selected from diethylene glycol, triethylene glycol, glycerin, triethylene glycol monobutyl ether, 1,5-pentanediol, 1,2-hexanediol, isopropanol, triethanolamine, and 2-pyrrolidone The black ink composition according to claim 10, further comprising a solvent.   The black ink composition according to claim 1, further comprising a surfactant.   The black ink composition according to claim 1, further comprising a preservative.   The black ink composition according to claim 1, wherein the viscosity is 1 to 20 mPa · sec.   The black ink composition according to claim 1, wherein the surface tension is 20 to 50 mN / m.   The black ink composition according to any one of claims 1 to 17, wherein the pH is 7 to 9.   An ink set comprising the black ink composition according to claim 1.   Image formation using the black ink composition according to any one of claims 1 to 18 or the ink set according to claim 19 on an image receiving material having an ink receiving layer containing white inorganic pigment particles on a support. An ink jet recording method comprising: