JP2012236954A - Black inkjet ink, ink cartridge and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black inkjet ink which gives high image density, avoids blurring, has excellent light resistance, and ensures excellent safety because no carbon black is used, and to provide an ink cartridge and an inkjet recording method using the ink.SOLUTION: (1) The black inkjet ink comprises at least water, a black colorant and a surfactant, wherein the black colorant is a metal-containing azo dye and the surfactant is a nonionic or anionic surfactant. (2) The ink cartridge houses the black inkjet ink in a container.

Description

  The present invention relates to an inkjet black ink, an ink cartridge using the ink, and an inkjet recording method.

The choice and dispersion of colorants is very important in aqueous inks. Colorants are roughly classified into dyes and pigments. Each has advantages and disadvantages, and is properly used according to the image quality target and cost.
However, inks using conventional dyes have vivid colors and are inexpensive, but there are problems with image quality such as insufficient coloring power, bleeding, bleeding, and poor light resistance. There is a problem that the color fades.
On the other hand, the ink using the pigment is excellent in coloring power and light resistance because the pigment has fastness, but it is necessary to finely disperse the pigment. From the pigment particle size and the characteristics of the pigment itself, the nozzle of the inkjet is clogged, There is a problem that filter clogging occurs and abnormal images such as image smearing and fading due to defective ejection occur.

By the way, as for black ink, those using a black dye and those using a carbon black pigment are put on the market. However, there are problems similar to those of inks using other dyes and pigments. Moreover, in the case of using a carbon black pigment, the manufacturing process of the pigment dispersion is complicated, it is difficult to make fine particles, there is a problem in ejection stability due to the pigment structure, and the cost of the pigment itself is high. Carbon black is classified as an ultrafine particle, and there are concerns about health effects such as accumulation in the lungs, and there are safety issues such as carcinogenicity at IARC (International Cancer Institute). Yes.
On the other hand, Patent Document 1 discloses each color ink using a dye for the purpose of obtaining an ink having a high image density and excellent color developability, and also describes a black ink using a black dye. The black dyes have insufficient light resistance, and are not black inks that satisfy all of the image quality, light resistance, ejection stability, cost, and safety.

  An object of the present invention is to provide an inkjet black ink having a high image density, no bleeding, excellent light resistance, and excellent safety without using carbon black, an ink cartridge using the ink, and an inkjet recording method. .

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by using a metal-containing azo dye having excellent light resistance and coloring ability, and has reached the present invention.
That is, the above-mentioned problems are solved by the following inventions 1) to 3).
1) For inkjet, comprising at least water, a black colorant, and a surfactant, wherein the black colorant is a metal-containing azo dye, and the surfactant is a nonionic or anionic surfactant. Black ink.
2) An ink cartridge comprising the ink-jet black ink according to 1) contained in a container.
3) An inkjet recording method comprising at least an ink flying process using the black ink for inkjet according to 1) and applying an stimulus to the ink to fly to form an image.

  According to the present invention, it is possible to provide an inkjet black ink having high image density, no bleeding, excellent light resistance, and excellent safety without using carbon black, an ink cartridge using the ink, and an inkjet recording method.

1 is a diagram illustrating an example of an ink jet recording apparatus.

Hereinafter, the present invention will be described in detail.
The metal-containing azo dye used in the black ink for ink jet of the present invention (hereinafter sometimes referred to as black ink) has excellent light resistance and coloring power, but is extremely robust and insoluble in water, and can be dispersed as a water-based ink. very difficult. As a result of investigation, it was found that the dispersion can be achieved by adding mechanical processing and further using a specific surfactant.
The metal-containing azo dye used in the present invention has a property of being easily electrically negatively charged. For this reason, in order to disperse these dyes in water, it is preferable to use a nonionic or anionic surfactant as a dispersing agent, which can prevent secondary aggregation and lead to stable dispersion.

上記式中、ＭはＣｒ又はＦｅ、ＸはＨ又はＮＯ_２、ＹはＮＯ_２又はＣｌ、Ａ^＋はＨ^＋又はＮＨ_４ ^＋を表す。

上記式中、Ｘ、ＹはＨ、Ｃｌ、ＮＯ_２のいずれかを表し、Ａ^＋はＨ^＋、Ｎａ^＋、ＮＨ_４ ^＋のいずれかを表す。

上記式中、Ｘ、ＹはＨ又はＮＯ_２を表し、Ａ^＋はＨ^＋、Ｎａ^＋、Ｋ^＋、ＮＨ_４ ^＋のいずれかを表す。 Preferred metal-containing azo dyes include those represented by the following general formulas (I), (II) and (III).

In the above formula, M represents Cr or Fe, X represents H or NO ₂ , Y represents NO ₂ or Cl, and A ⁺ represents H ⁺ or NH ₄ ⁺ .

In the above formulas, X and Y represent any of H, Cl, and NO ₂ , and A ⁺ represents any of H ⁺ , Na ⁺ , and NH ₄ ⁺ .

In the above formulas, X, Y is H or NO _2, ^{A +} represents any ^{H +, Na +, K +} , NH 4 + in.

Specific examples of the metal-containing azo dye represented by the above general formula include the following compounds (1) to (9). Compounds (1) to (2) are examples of general formula (I), compounds (3) to (8) are examples of general formula (II), and compound (9) is an example of general formula (III).

As the surfactant used in the present invention, those having an HLB value of 10 to 20 are preferable. HLB (Hydrophile-Lipophile Balance) is an index representing the hydrophilicity of a surfactant, and represents the balance between hydrophilicity and hydrophobicity by numerical values. In the present invention, Griffin HLB is used. This is a method proposed by Mr. Griffin of Atlas, Inc. in the United States, and is a calculation method that is currently widely used. The calculation formula is as follows.

  Nonionic surfactants having an HLB value of 10 to 20 include, for example, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene polycyclic phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxy Examples include ethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, and acetylene glycol. Among these, polyoxyethylene lauryl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene sorbitan monooleate, and polyoxyethylene styrene phenyl ether are particularly preferable. These surfactants are characterized in that the viscosity of the dispersion is not significantly affected even when the concentration changes.

Examples of the anionic surfactant having an HLB value of 10 to 20 include polyoxyethylene alkyl ether acetates, alkylbenzene sulfonates (for example, NH ₄ , Na, Ca, etc.), alkyl diphenyl ether disulfonates (for example, NH ₄ , Na, Ca, etc.), dialkyl succinate sulfonic acid Na salt, naphthalene sulfonic acid formalin condensate Na salt, polyoxyethylene polycyclic phenyl ether sulfate ester salt (for example, NH ₄ , Na etc.), laurate, polyoxy An ethylene alkyl ether sulfate salt, an oleate, etc. are mentioned. Among these, naphthalene sulfonic acid formalin condensate Na salt, dioctyl sulfosuccinic acid Na salt, and polyoxyethylene styrene phenyl ether sulfonic acid NH ₄ salt are preferable.

  There is no restriction | limiting in particular about the addition amount of the said surfactant, Although it can select suitably according to the objective, 10-50 mass% of the whole ink is preferable. When the content is 10% by mass or more, the storage stability of the metal-containing azo dye dispersion and the black ink is not deteriorated or extremely long time is not required for dispersion. There is no case where the viscosity of the ink becomes too high and the ejection stability is not lowered.

  Since the metal-containing azo dye is strong and insoluble in water, it is difficult to disperse by a conventionally known aqueous dispersion method. Therefore, the metal-containing azo dye is first finely pulverized by a conventionally known dry pulverization method (impact plate pulverization method, mechanical pulverization method, airflow pulverization method, etc.) so that the volume average particle diameter of the metal-containing azo dye becomes 1 to 3 μm. Subsequently, the obtained fine particles are stirred and mixed in an aqueous solution in which a surfactant is dissolved, and dispersed until the volume average particle diameter D90 becomes 10 to 200 nm. By this operation, the metal-containing azo dye is favorably and uniformly dispersed in the ink, and it is possible to provide a black ink having high image density, no bleeding, and excellent light resistance, which is the subject of the present invention.

  The collision plate type pulverization method is a method in which a coloring material is poured into a high-speed air stream and collided with a ceramic plate to crush the coloring material. For example, a collision plate type supersonic jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.) Etc. The mechanical pulverization method is a method in which an air current and a coloring material are passed through a gap between a rotor rotating at a high speed and a fixed stator and crushed. For example, a mechanical vortex pulverizer (Kryptron Zepros: manufactured by Earth Technica) ) And the like. The airflow-type pulverization method is a method in which high-speed jet air collides against each other, and a colorant is caused to flow in the air to be crushed. For example, an airflow-type pulverizer (counter jet mill: manufactured by Hosokawa Micron Corporation) is used. . In the case of the counter jet mill 100AFG, the air pressure is set to 0.5 MPa, and the metal-containing azo dye is allowed to flow at 0.5 to 0.7 kg / h to obtain a particle diameter of 1 to 3 μm.

  In order to disperse the finely pulverized fine particles by the dry pulverization method in an aqueous system, a conventionally known method can be used. That is, the fine particles are stirred and mixed in an aqueous solution in which a surfactant is dissolved, and then dispersed by a bead mill, a roll mill, a ball mill, a sand mill, a basket mill or the like. For example, when Ultra Apex Mill UAM-015 manufactured by Kotobuki Kogyo Co., Ltd. is used as a bead mill, when the dispersion liquid is circulated at a peripheral speed of 14 m / s using 0.5 μm zirconia beads, the volume average particle size of the metal-containing azo dye The diameter D90 can be 10 to 200 nm.

The black ink of the present invention is blended with known additives such as a penetrating agent (surfactant), a polyurethane resin emulsion, a wetting agent (water-soluble organic solvent), a pH adjuster, an antiseptic / antifungal agent, and a rust preventive agent. Can do.
<Penetration agent (surfactant)>
The penetrating agent (surfactant) is not particularly limited and may be appropriately selected depending on the purpose. For example, nonionic surfactants, anionic surfactants, and amphoteric surfactants having different polarities of hydrophilic groups Etc. Further, there are fluorine-based surfactants, silicone-based surfactants, acetylene-based surfactants and the like having different hydrophobic group structures.
When penetrant (surfactant) is added to ink, the surface tension decreases, and the penetration of ink into the recording medium after landing on the recording medium such as paper becomes faster, reducing feathering and color bleeding. be able to. In addition, the range of the appropriate surface tension of the black ink of the present invention is 20 to 35 mN / m.

There is no restriction | limiting in particular as said nonionic surfactant, According to the objective, it can select suitably, For example, a polyol, glycol ether, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl Examples include esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amines, polyoxyethylene alkyl amides, and acetylene glycols.
The anionic surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, lauryl alcohol sulfate such as polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, and sodium lauryl sulfate. And salts of polyoxyethylene alkyl ether sulfate.
There is no restriction | limiting in particular as said fluorosurfactant, According to the objective, it can select suitably, For example, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate ester, perfluoroalkyl Examples thereof include ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkylamine oxide compounds.

There is no restriction | limiting in particular as said silicone type surfactant, According to the objective, it can select suitably, For example, a polyether modified silicone compound etc. are mentioned.
The polyether-modified silicone compound is not particularly limited and may be appropriately selected depending on the intended purpose. The side chain type (pendant type) in which a polyether group is introduced into the side chain of the polysiloxane, one end of the polysiloxane One-end type in which a polyether group is introduced, double-end type (ABA type) introduced in both ends, side-chain both-end type in which a polyether group is introduced into both side chains and both ends of a polysiloxane, polyether group ABn type in which polysiloxane (A) having introduced therein and polysiloxane (B) not introduced is repeatedly bonded, and branched type in which a polyether group is introduced into the terminal of branched polysiloxane. Among these, a side chain type (pendant type) having a structure in which a polyether group is introduced into a side chain of polysiloxane is preferable.
There is no restriction | limiting in particular as said acetylene glycol type surfactant, According to the objective, it can select suitably, For example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3 And acetylene glycols such as 3,6-dimethyl-4-octyne-3,6-diol and 3,5-dimethyl-1-hexyn-3-ol.

Two or more penetrants (surfactants) may be used in combination. In order to improve the permeability, a polyol having 8 to 11 carbon atoms such as 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol may be used in combination.
There is no restriction | limiting in particular as addition amount of a penetrant, Although it can select suitably according to the objective, 0.05-5 mass% is preferable with respect to black ink whole quantity, and 0.1-3 mass% is more preferable. .

<Polyurethane resin emulsion>
The polyurethane resin emulsion is contained for the purpose of improving the dispersion stability of the metal-containing azo dye dispersion and improving the fixability (scratch resistance) of the printed material.
The polyurethane resin is not particularly limited and can be appropriately selected according to the purpose. For example, a polyisocyanate and a polyol obtained by polymerizing a polyol such as a polyether polyol, a polyester polyol, a polylactone polyol, and a polycarbonate polyol can be used. Can be mentioned.

  The polyisocyanate is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include aliphatic diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene. Cycloaliphatic diisocyanate compounds such as diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, aromatic aliphatic diisocyanate compounds such as xylylene diisocyanate, tetramethylxylene diisocyanate, toluylene diisocyanate, phenylmethane diisocyanate, etc. Aromatic diisocyanate compounds, modified products of these diisocyanates (carbodiimide, uretdione, ureitoimine-containing modifications) Things like), and the like.

There is no restriction | limiting in particular as said polyether polyol, According to the objective, it can select suitably, For example, polyethyleneglycol, polypropylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol etc. are mentioned.
The polyester polyol is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyethylene adipate, polybutylene adipate, polyneopentyl adipate, poly-3-methylpentyl adipate, polyethylene / butylene adipate, polyneo And pentyl / hexyl adipate.
There is no restriction | limiting in particular as said polylactone polyol, According to the objective, it can select suitably, For example, polycaprolactone diol, polyomega hydroxycaproic acid polyol, etc. are mentioned.

  There is no restriction | limiting in particular as said polycarbonate polyol, According to the objective, it can select suitably, For example, 1, 3- propanediol, 1, 4- butanediol, 1, 6- hexanediol, diethylene glycol, triethylene glycol, Examples include known products such as products obtained by reaction of diols such as tetraethylene glycol; phosgene; diaryl carbonates such as diphenyl carbonate; and cyclic carbonates such as ethylene carbonate and propylene carbonate. Moreover, the polyester carbonate obtained by reaction of polyester or polylactone, phosgene, and diaryl carbonate or cyclic carbonate is also suitable.

Polyurethane resin emulsions exhibit more excellent water dispersibility by introducing ionic groups into the resin.
The ionic group is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include sulfonic acid groups, carboxylic acid groups, sulfuric acid groups, phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, and alkalis thereof. And metal bases, alkaline earth metal bases, ammonium bases, primary to tertiary amine groups, and the like. Among these, alkali metal carboxylate, ammonium carboxylate, alkali metal sulfonate, and ammonium sulfonate are preferable, and alkali metal sulfonate and ammonium sulfonate are preferable in terms of water dispersion stability. .
There is no restriction | limiting in particular as said salt, According to the objective, it can select suitably, For example, Li, K, Na salt, etc. are mentioned.
The ionic group can be introduced by adding a monomer having an ionic group during the synthesis of the resin.

<Wetting agent (water-soluble organic solvent)>
The black ink of the present invention uses water as a liquid medium, but it is preferable to contain a water-soluble organic solvent as a wetting agent for preventing the ink from drying and for the purpose of improving dispersion stability. .
There is no restriction | limiting in particular as a wetting agent (water-soluble organic solvent), According to the objective, it can select suitably, For example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol , Tripropylene glycol, polypropylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, trimethylolethane, trimethylolpropane, Polyhydric alcohols such as 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,6-hexanetriol, petriol; ethylene glycol monoethyl ether, ethylene glycol monobuty Polyhydric alcohol alkyl ethers such as ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether; polyvalent alcohols such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether Alcohol aryl ethers; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone Amides such as formamide, N-methylformamide, N, N-dimethylformamide; monoethanolamine, diethanolamine Triethanolamine, monoethylamine, diethylamine, amines such as triethylamine; dimethyl sulfoxide, sulfolane, sulfur-containing compounds such as thiodiethanol; propylene carbonate, ethylene carbonate, and the like. These may be used individually by 1 type and may use 2 or more types together.

In addition to the wetting agent (water-soluble organic solvent), other wetting agents may be blended. There is no restriction | limiting in particular as another wetting agent, Although it can select suitably according to the objective, Sugar is preferable.
There is no restriction | limiting in particular as saccharides, According to the objective, it can select suitably, For example, a monosaccharide, a disaccharide, an oligosaccharide (a trisaccharide and a tetrasaccharide are included), a polysaccharide, etc. are mentioned. Specific examples include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. In addition, the said polysaccharide means saccharide | sugar in a broad sense, and shall use it for the meaning containing the substance which exists widely in nature, such as (alpha) -cyclodextrin and a cellulose. Derivatives of these saccharides can also be used. For example, reducing sugars of the aforementioned saccharides {for example, sugar alcohol [general formula HOCH ₂ (CHOH) nCH ₂ OH (n = 2 to 5)]}, oxidation Examples include sugars (for example, aldonic acid, uronic acid, etc.), amino acids, thioic acids, and the like. Among these, sugar alcohols such as D-sorbitol, sorbitan, maltitol, erythritol, lactitol, and xylitol are preferable. In particular, in the present invention, when glycerin, 1,3-butanediol, and 3-methyl-1,3-butanediol are used, a black ink excellent in storage stability and ejection stability can be produced.

<PH adjuster>
The pH adjuster is added for the purpose of stabilizing the dispersion state by keeping the ink alkaline and stabilizing ejection. However, when the pH is 11 or higher, the amount of the ink jet head and the ink supply unit that melts out is large, and problems such as ink deterioration, leakage, and ejection failure occur.
There is no restriction | limiting in particular as a pH adjuster, Although it can select suitably according to the objective, One or more types of alcohol amines, alkali metal hydroxide, ammonium hydroxide, phosphonium hydroxide, alkali metal carbonate are used. The inclusion is preferred.
There is no restriction | limiting in particular as said alcohol amine, According to the objective, it can select suitably, Diethanolamine, a triethanolamine, 2-amino-2-ethyl- 1, 3- propanediol, etc. are mentioned.
The alkali metal hydroxide is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include lithium hydroxide, sodium hydroxide and potassium hydroxide.
There is no restriction | limiting in particular as said ammonium hydroxide, According to the objective, it can select suitably, Ammonium hydroxide, a quaternary ammonium hydroxide, etc. are quaternary phosphonium hydroxide as a phosphonium hydroxide. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

<Antiseptic and antifungal agent>
The antiseptic / antifungal agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol 1,2-benzisothiazolin-3-one and the like.

<Rust preventive>
The rust inhibitor is not particularly limited and may be appropriately selected according to the purpose.For example, acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, dicyclohexyl ammonium nitrite, 1,2,3-benzotriazole and the like.

The black ink of the present invention can be produced by a known method. For example, it can be obtained by stirring and mixing a metal-containing azo dye dispersion, water, a water-soluble organic solvent, a surfactant and the like, filtering coarse particles with a filter, a centrifugal separator, and the like, and deaeration as necessary.
The black ink of the present invention can be used by being housed in an ink cartridge and mounted on an ink jet recording apparatus.

(ink cartridge)
The ink cartridge of the present invention is an ink cartridge containing the black ink of the present invention in a container. There are no particular restrictions on the container, and its shape, structure, size, material, etc. can be appropriately selected according to the purpose, for example, an ink bag formed of an aluminum laminate film, a resin film, etc. A plastic case or the like is suitable.

(Inkjet recording method, inkjet recording apparatus)
The black ink of the present invention can be applied to an ink jet recording method including at least an ink flying process in which an image is formed by applying a stimulus to the ink and flying the ink.
The black ink of the present invention can be applied to various known ink jet recording apparatuses.
Examples of a method for printing by discharging ink in an ink jet recording apparatus include a continuous jet type and an on-demand type. Examples of the on-demand type include a piezo method, a thermal method, and an electrostatic method.

FIG. 1 shows an example of an ink jet recording apparatus.
In FIG. 1, the ink cartridge 20 is accommodated in the carriage 18. A plurality of ink cartridges 20 are provided for convenience, but the number may not be plural. In such a state, the ink for inkjet is supplied from the ink cartridge 20 to the droplet discharge head 18 a mounted on the carriage 18. In FIG. 1, the discharge nozzle surface is not visible because it faces downward, but ink jet ink is discharged from the discharge nozzle.
The droplet discharge head 18 a mounted on the carriage 18 is guided and moved by the guide shafts 21 and 22 by the timing belt 23 driven by the main scanning motor 26.
On the other hand, the recording medium is placed at a position facing the droplet discharge head 18 a by the platen 19. In FIG. 1, 1 is an ink jet recording apparatus, 2 is a main body housing, 16 is a gear mechanism, 17 is a sub-scanning motor, 24 is a main scanning motor, and 25 and 27 are gear mechanisms.

When an image was formed on a recording medium using the black ink of the present invention and other ink-jet ink or an ink-jet recording apparatus equipped with an ink cartridge containing these inks, it was printed on the recording medium on demand. An ink record is obtained. Ink replenishment can be replaced in units of ink cartridges.
There is no restriction | limiting in particular as said recording medium, According to the objective, it can select suitably, For example, a plain paper, glossy paper, special paper, cloth, a film, an OHP sheet etc. are mentioned. Among these, paper is particularly preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not restrict | limited at all by these Examples. In the examples, “part” is “part by mass”.

Examples 1-11, Comparative Examples 1-2
<Preparation of metal-containing azo dye dispersion>
16 parts of each metal-containing azo dye of the above-mentioned compounds (1) to (9) as a black colorant, (a) Naphthalene sulfonic acid formalin condensate Na salt (A-45-PN: Takemoto Yushi Co., Ltd.) as an anionic surfactant 1 part) and 83 parts of distilled water, 16 parts of each of the same metal-containing azo dyes, (b) polyoxyethylene alkyl ether (Emalmine NL-70: Sanyo Chemical) as a nonionic surfactant Dispersions K1 to K11 shown in Table 1 below were prepared using 1 part of Kogyo Co., Ltd. and 83 parts of distilled water.
As the operation, first, the metal-containing azo dye was finely pulverized with an airflow pulverizer (counter jet mill: manufactured by Hosokawa Micron Co., Ltd.) so that the volume average particle diameter became 1.5 to 3 μm. Next, a surfactant was dissolved in distilled water, and the finely pulverized metal-containing azo dye was added thereto and dispersed by stirring. Subsequently, it was dispersed with a bead mill disperser (Ultra Apex Mill UAM-015: manufactured by Kotobuki Kogyo Co., Ltd.) until the volume average particle diameter D90 became 150 to 200 nm.

<Preparation of ink>
Dispersions K1 to K11 were used for the examples, and the following dyes 1 and 2 were used for the comparative examples, and the inks of the examples and comparative examples were prepared by mixing and stirring the materials having the formulations shown in Table 2.
Dye 1; C.I. I. Disperse Black 1
Dye 2; C.I. I. Disperse Black 10
In addition, the function of each material in Table 2 is as follows.
Water-soluble organic solvent: glycerin, 3-methyl-1,3-butanediol, 2-pyrrolidone Surfactant: Naphthalenesulfonic acid formalin condensate Na salt (A-45-PN: Takemoto oil)
(Made by Seiya)
Penetration agent: 2,2,4-trimethyl-1,3-pentanediol Antiseptic / antifungal agent: 1,2-benzisothiazolin-3-one Rust preventive agent: 1,2,3-benzotriazole pH adjusting agent: 2- Amino-2-ethyl-1,3-propanediol Urethane resin: Urethane resin emulsion (W-5661: manufactured by Mitsui Chemicals)

<Evaluation of ink>
About each said ink, it printed using the Ricoh inkjet printer of the structure shown in FIG. 1, and image density, a blur, and light resistance were evaluated. The results are shown in Table 2.
[Image density]
A solid black image of 3 cm × 10 cm is printed on plain paper, and the density of the obtained image is measured at five locations with a reflection densitometer (X-rite 939, manufactured by X-Rite). Based on the average value, Evaluated by criteria.
〔Evaluation criteria〕
○: Image density 1.3 or more Δ: Image density 1.1 or more and less than 1.3 ×: Image density 1.1 or less

[Smear]
A black solid image of 3 cm × 10 cm was printed on plain paper, and the boundary line of the obtained image was observed with a 30 × magnifier and evaluated according to the following criteria.
〔Evaluation criteria〕
○: No image blur ×: Image blur

[Light resistance]
Print a 3cm x 10cm black solid image on plain paper, cut out the resulting image, cover it with aluminum foil, and irradiate it with a xenon weather meter (XL75, manufactured by Suga Test Instruments Co., Ltd.) for 24 hours. The portion covered with the foil was measured with a reflection densitometer (X-rite 939, manufactured by X-Rite), and the color difference ΔE was calculated and evaluated according to the following criteria.
〔Evaluation criteria〕
○: 0 ≦ ΔE ≦ 0.5
Δ: 0.5 <ΔE ≦ 1.5
×: 1.5 <ΔE

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Main body housing | casing 16 Gear mechanism 17 Subscanning motor 18 Carriage 18a Droplet discharge head 19 Platen 20 Ink cartridge 21 Guide shaft 22 Guide shaft 23 Timing belt 24 Main scanning motor 25 Gear mechanism 26 Main scanning motor 27 Gear mechanism

JP 2004-246426 A

Claims (3)

  An ink jet black ink comprising at least water, a black colorant, and a surfactant, wherein the black colorant is a metal-containing azo dye, and the surfactant is a nonionic or anionic surfactant. .   An ink cartridge comprising the ink-jet black ink according to claim 1 contained in a container.   An ink jet recording method comprising at least an ink flying step of using the black ink for ink jet according to claim 1 and applying an stimulus to the ink to fly to form an image.

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