JP2005239822A - Black water-based ink composition, inkjet recording method using the same and recorded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a black water-based ink composition that has excellent light resistance, storage stability in a photo album and moisture resistance, produces a printed article keeping a high-quality image for a long period of time and improved ozone resistance. <P>SOLUTION: The black water-based ink composition comprises at least one kind selected from the group consisting of a compound represented by formula (1) [R<SP>1</SP>is a substituent group-containing phenyl group or a substituent group-containing naphthyl group; R<SP>2</SP>is a substituent group-containing phenylene group or a substituent group-containing naphthylene group; R<SP>3</SP>is a heterocyclic group of a 5-7 membered ring having at least one double bond and a substituent group; the substituent groups in R<SP>1</SP>-R<SP>3</SP>are each independently selected from OH, SO<SB>3</SB>H, PO<SB>3</SB>H<SB>2</SB>, CO<SB>2</SB>H, NO<SB>2</SB>, NH<SB>2</SB>, a 1-4C alkyl group, a substituent group-containing alkyl group, a 1-4C alkoxy group, or the like] and its salt as a black dye. The black water-based ink composition contains at least one kind of a compound that can contain the black dye. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a black aqueous ink composition that can be suitably used for ink jet recording, an ink jet recording method using the composition, and a recorded matter recorded by the recording method.

  The ink jet recording method is a known method in which ink composition is ejected as small droplets from a thin nozzle, and characters and images are attached to the surface of the recording medium for recording. Ink jet recording methods in practical use include: (i) using an electrostrictive element to convert an electrical signal into a mechanical signal, and the ink composition stored in the nozzle head portion is intermittently ejected from the nozzle head by this mechanical signal. A method of recording characters and images by attaching the ink composition to the surface of the recording medium, and (ii) rapidly heating a portion very close to the discharge portion of the nozzle head into the ink composition stored in the nozzle head portion. There is a method of recording characters and images by generating bubbles, ejecting the ink composition intermittently from the nozzle head by the volume expansion of the bubbles, and attaching the ink composition to the surface of the recording medium.

  The ink composition used in the ink jet recording method is generally a solution in which various dyes are dissolved in water, an organic solvent, or a mixture thereof, and this ink composition is used for writing instruments such as fountain pens and ballpoint pens. Compared with other inks, higher safety and better printing characteristics are required.

  In recent years, inkjet printers have been adopted for the production of printed materials for advertisement, and printed materials produced by an ink jet recording method using a water-based ink composition are installed not only indoors but also outdoors. . Therefore, exposure to sunlight and / or light from various light sources and chemical substances such as ozone, nitrogen oxides, and sulfur oxides contained in the atmosphere may prevent the image quality of the printed matter from deteriorating over time. It is necessary. In response to this requirement, various studies have been made on color inks such as yellow, magenta, and cyan. The development of the black ink was delayed due to the low fastness of use in the image and the high concentration of the dye, because the fastness of the ink itself was higher than that of the color ink. However, the black ink is important from the viewpoint of obtaining image contrast in an image, and has been accelerated in recent years in combination with the improvement of the characteristics of the color ink.

  Under such circumstances, as a dye capable of improving the gas resistance, particularly ozone resistance of an ink composition using a dye as a colorant, for example, a disazo dye having the following structure is known (for example, (See Patent Document 1 and Patent Document 2.)

  However, even the ink composition using the above dye has insufficient light resistance and ozone resistance, and there is a problem that the image quality of the printed material deteriorates with time, for example, fades when the printed material is exposed to light and ozone. there were. On the other hand, the present inventors have found that excellent light resistance and ozone resistance can be obtained by using a dye represented by the following formula (1), and have proposed a black aqueous ink composition using the same ( Japanese Patent Application No. 2003-169423).

（前記式（１）中、Ｒ¹は置換基を有するフェニル基または置換基を有するナフチル基を表し、Ｒ²は置換基を有するフェニレン基または置換基を有するナフチレン基を表し、Ｒ³は少なくとも１つの二重結合及び置換基を有する５〜７員環の複素環基を表す。さらに前記Ｒ¹〜Ｒ³における前記置換基は独立して、ＯＨ、ＳＯ₃Ｈ、ＰＯ₃Ｈ₂、ＣＯ₂Ｈ、ＮＯ₂、ＮＨ₂、Ｃ１〜４のアルキル基、置換基を有するアルキル基、Ｃ１〜４のアルコキシ基、置換基を有するアルコキシ基、アミノ基、置換基を有するアミノ基、及び置換基を有するフェニル基からなる群から選ばれる。）

(In the formula (1), R ¹ represents a phenyl group having a substituent or a naphthyl group having a substituent, R ² represents a phenylene group having a substituent or a naphthylene group having a substituent, and R ³ is at least It represents a 5- to 7-membered heterocyclic group having one double bond and a substituent, and the substituent in R ^{1 to} R ³ is independently OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NO ₂ , NH ₂ , a C1-4 alkyl group, a substituted alkyl group, a C1-4 alkoxy group, a substituted alkoxy group, an amino group, a substituted amino group, and a substituent Selected from the group consisting of phenyl groups having

Japanese Patent Laid-Open No. 3-229770 Japanese Patent Laid-Open No. 3-91576

  The present invention is capable of producing a printed matter that is excellent in light resistance, album storage resistance, and moisture resistance, and that can maintain a high-quality image over a long period of time, and further has improved ozone resistance. An aqueous ink composition, an ink jet recording method using the same, and a recorded matter recorded by the ink jet recording method are provided.

As a result of intensive studies in view of the above problems, the present inventors have further improved ozone resistance when the ink composition contains a compound that can be included in the ink composition together with the compound represented by the above formula (1). Based on this finding, the present inventors have made the present invention.
That is, the said subject was solved by the following invention.
1. A black aqueous ink composition containing at least one selected from the group consisting of a compound represented by the following formula (1) and a salt of the compound represented by the formula (1) as a black dye, wherein the black dye is A black aqueous ink composition comprising at least one compound capable of inclusion.

（前記式（１）中、Ｒ¹は置換基を有するフェニル基または置換基を有するナフチル基を表し、Ｒ²は置換基を有するフェニレン基または置換基を有するナフチレン基を表し、Ｒ³は少なくとも１つの二重結合及び置換基を有する５〜７員環の複素環基を表す。さらに前記Ｒ¹〜Ｒ³における前記置換基は独立して、ＯＨ、ＳＯ₃Ｈ、ＰＯ₃Ｈ₂、ＣＯ₂Ｈ、ＮＯ₂、ＮＨ₂、Ｃ１〜４のアルキル基、置換基を有するアルキル基、Ｃ１〜４のアルコキシ基、置換基を有するアルコキシ基、アミノ基、置換基を有するアミノ基、及び置換基を有するフェニル基からなる群から選ばれる。）

(In the formula (1), R ¹ represents a phenyl group having a substituent or a naphthyl group having a substituent, R ² represents a phenylene group having a substituent or a naphthylene group having a substituent, and R ³ is at least It represents a 5- to 7-membered heterocyclic group having one double bond and a substituent, and the substituent in R ^{1 to} R ³ is independently OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NO ₂ , NH ₂ , a C1-4 alkyl group, a substituted alkyl group, a C1-4 alkoxy group, a substituted alkoxy group, an amino group, a substituted amino group, and a substituent Selected from the group consisting of phenyl groups having

2. 2. The black aqueous ink composition as described in 1 above, wherein the black aqueous ink composition contains 0.1 to 30% by weight of a compound capable of including the black dye.
3. In the black aqueous ink composition, a compound capable of including the black dye and at least one selected from the group consisting of a compound represented by the formula (1) and a salt of the compound represented by the formula (1) The black aqueous ink composition as described in 1 or 2 above, wherein the weight ratio is 3: 1 to 1: 5.
4). The black aqueous ink composition according to any one of 1 to 3, wherein the compound capable of including the black dye is cyclodextrin.
5). 5. The black aqueous ink composition as described in 4 above, wherein the cyclodextrin is α-cyclodextrin.
6). 6. The black aqueous ink composition according to any one of 1 to 5, wherein the compound represented by the formula (1) is a compound represented by the following formula (2).

（前記式（２）中、Ｒ¹〜Ｒ⁹は独立して、Ｈ、ＯＨ、ＳＯ₃Ｈ、ＰＯ₃Ｈ₂、ＣＯ₂Ｈ、ＮＯ₂、及びＮＨ₂からなる群から選ばれる基を表す。）

(In the formula (2), R ^{1 to} R ⁹ independently represent a group selected from the group consisting of H, OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NO ₂ , and NH _2. .)

7). The black aqueous ink composition according to any one of 1 to 6, wherein the black dye is contained in the black aqueous ink composition in an amount of 0.5 to 12% by weight.
8). The black aqueous ink composition according to any one of 1 to 7, wherein the black aqueous ink composition contains an acetylene glycol surfactant.
9. The black aqueous ink composition according to any one of 1 to 8, wherein the black aqueous ink composition contains a glycol ether-based aqueous organic solvent.
10. The black aqueous ink composition according to any one of 1 to 9, wherein the pH of the ink composition at 20 ° C. is 10.5 or less.
11. The black aqueous ink composition according to any one of 1 to 10, which is used in an inkjet recording method.
12 12. The black aqueous ink composition according to 11, wherein the inkjet recording method is a recording method using an inkjet head that forms ink droplets by mechanical deformation of an electrostrictive element.

13. 13. An ink jet recording method for performing recording by discharging a droplet of an ink composition and attaching the droplet to a recording medium, wherein the black aqueous ink composition according to any one of 1 to 12 above is used as the ink composition An ink jet recording method using an object.
14 A recorded matter recorded using the black aqueous ink composition according to any one of 1 to 12 above or recorded by the recording method according to 13.

  A recorded matter in which an image is recorded on a recording medium by the inkjet recording method using the black aqueous ink composition of the present invention is not easily blackened even when exposed to light. There is little bleeding and very high ozone resistance.

  The black aqueous ink composition of the present invention (hereinafter, also simply referred to as “ink composition”) is a compound represented by the following formula (1) in water or an aqueous medium comprising water and a water-soluble organic solvent. And one or more selected from the group consisting of salts of compounds represented by formula (1).

In the above formula (1), R ¹ represents a phenyl group having a substituent or a naphthyl group having a substituent. Further, in formula (1), R ² represents a phenylene group having a substituent or a naphthylene group having a substituent. Further, in formula (1), R ³ represents a 5- to 7-membered heterocyclic group having at least one double bond and a substituent. Further, the substituents in R ^{1 to} R ³ are independently OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NO ₂ , NH ₂ , a C1-4 alkyl group, a substituted alkyl group, C1 -4 represents a group selected from the group consisting of alkoxy groups, substituted alkoxy groups, amino groups, substituted amino groups, and substituted phenyl groups.

Further substituted alkyl groups _{mentioned, OH, SO 3 H, PO} 3 H 2, CO 2 H, and C1~4 alkyl substituted with one or more groups selected from the group consisting of NH ₂ group It is preferably selected from the group. Also, substituted alkoxy groups _{mentioned, OH, SO 3 H, PO} 3 H 2, CO 2 H, and C1~4 alkoxy substituted with one or more groups selected from the group consisting of NH ₂ group It is preferably selected from the group. Further, substituted amino groups _{mentioned, OH, SO 3 H, PO} 3 H 2, CO 2 H, and from the group consisting of NH ₂ groups selected been C1~4 substituted with one or more groups It is preferably selected from the group consisting of amino groups having one or two alkyl groups. The substituted phenyl group is a group consisting of OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NH ₂ , a C1-4 alkyl group, and a substituted C1-4 alkyl group. It is preferably selected from the group consisting of phenyl groups having one or two substituents selected from:

  Further, the compound represented by the above formula (1) used in the present invention is particularly preferably a compound represented by the following formula (2).

（式（２）中、Ｒ¹〜Ｒ⁹は独立して、Ｈ、ＯＨ、ＳＯ₃Ｈ、ＰＯ₃Ｈ₂、ＣＯ₂Ｈ、ＮＯ₂、及びＮＨ₂からなる群から選ばれる基を表す。）

(In the formula (2), R ^{1 to} R ⁹ independently represent a group selected from the group consisting of H, OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NO ₂ , and NH ₂ . )

  The black aqueous ink composition of the present invention is a composition containing at least one or more black dyes, and the black dye is a compound represented by the above formula (1) (hereinafter also simply referred to as compound (1)). And at least one selected from the group consisting of salts of compound (1) is contained in the ink composition.

  As the compound (1) used in the ink composition of the present invention, compounds represented by the following formulas (3) to (9) are particularly preferable.

The compound represented by the above formula (1) or formula (2) used in the ink composition of the present invention can be appropriately synthesized using a preferred method. For example, each compound is bound by three azo groups. It can be synthesized by combining building blocks having each of the four corresponding structures by azo coupling. That is, for example, when the dihydroxynaphthalene skeleton portion represented by the formula (1) is represented by Q, the compound of the formula (1) is R ³ —N═N—R ² —N═N—Q—N═N—R Can be represented by ¹ . One specific method for synthesizing this compound is schematically shown. First, a diazonium salt obtained by diazotizing R ¹ —NH ₂ is reacted with QH to give R ¹ —N═N—QH. Next, the compound obtained by diazotizing CH ₃ CON-R ² —NH ₂ and R ¹ —N═N—QH are coupled to give R ¹ —N═NQN═N—R ² NCOCH ₃ . Synthesize. The acetyl group of this compound is removed to form an amino group and then diazotized, followed by coupling with R ³ H to synthesize R ¹ —N═N—Q—N═N—R ² —N═N—R ^3. it can.

Furthermore, as a specific example of synthesis, a synthesis example of the compound represented by the formula (3) will be described below.
5-acetylamino-2-aminobenzenesulfonic acid (23.0 g, 0.10 mol) was added to water (300 ml) containing concentrated nitric acid (30 ml). Sodium nitrite (6.9 g) was added over 10 minutes at a temperature of 0-5 ° C. After 60 minutes, excess nitrous acid was decomposed, and the resulting diazonium salt solution was slowly dissolved in water (500 g) while maintaining the pH of 8 to 9 at 5 to 10 ° C. To a solution of naphthalene-3,6-disulfonic acid (32.0 g, 0.10 mol). It was confirmed by HPLC that this reaction proceeded quantitatively. This gave a solution containing the coupling product (referred to as dye base).

Then 5-nitro-2-aminobenzenesulfonic acid (43.6 g, 0.20 mol) was added to water (500 g) containing concentrated hydrochloric acid (60 g). Sodium nitrite (13.8 g) was added over 15 minutes at a temperature of 0-5 ° C. After 60 minutes, the obtained diazonium salt solution was added to the above dye base to which tetrahydrofuran (1000 g) had been added in advance over 120 minutes while maintaining 5 to 10 ° C. and pH 6 to 7. After 5 hours, the resulting precipitate was collected and dried in a dryer to give a dark red solid (55.3 g). This dark red solid was dissolved in water (1000 ml) and heated to 80 ° C. Sodium hydroxide (10 g) was added and the temperature was kept at 80 ° C. for an additional 8 hours. After 8 hours, the pH was adjusted to 7-8 using concentrated hydrochloric acid, and the solution was allowed to cool to room temperature. The solution was dialyzed (less than 50 μScm ⁻¹ ) using Visking ™ tubing, then filtered using a filter and dried in a dryer to yield 47.2 g of a black solid.

The black solid obtained above was redissolved in water at pH 7-9, but lithium hydroxide was used to adjust the pH. Then sodium nitrite (8.3 g) was added and stirred for 10 minutes. The dye / nitrite solution was then transferred into ice water (100 ml) containing concentrated hydrochloric acid (30 g). On standing, the temperature rose to 15-25 ° C., but was left for 3 hours. The obtained diazodium salt solution was charged with 1- (4-sulfophenyl) -3-carboxy-5-pyrazolone (17.9 g, 0.06 mol) over 120 minutes while maintaining pH 15 to 20 ° C. and pH 6 to 7. ). This pH was maintained by adding lithium hydroxide. The solution is then dialyzed (less than 50 μScm ⁻¹ ) using Visking ™ tubing, further filtered using a filter and dried in a drier to yield 60.0 g of the compound represented by the formula (3). Obtained as a black solid.

In the present specification, the salt of the compound represented by the formula (1) includes a salt of the compound represented by the formula (1) and a partial salt of the compound represented by the formula (1). Further, the salt and the partial salt include complex salts. The partial salt of the compound (1) refers to a salt composed of the compound (1) with an ion equivalent to an amount less than the equivalent of the proton acid group of the compound (1). Moreover, the said complex salt means the case where one molecule of compound (1) forms a salt with two or more kinds of ions. Salts of the above compounds (1), alkali metal salts, ammonium salts of the compounds (1) is OH, SO ₃ H, the compound if it has a protonic acid group, such as PO ₃ H ₂ group (1) and, Examples of the organic ammonium salt and one or more selected from the group consisting of complex salts containing two or more selected from the group consisting of these various metals, ammonium, and organic ammonium can be exemplified, but the present invention is not limited thereto. . Examples of the alkali metal salt include lithium salts, sodium salts, potassium salts, cesium salts, and salts containing two or more of these metals, and lithium salts and sodium salts are particularly preferable.

  In the ink composition of the present invention, as the compound (1) and the salt of the compound (1), only one kind may be used, or two or more kinds may be used in combination. When two or more kinds are used in combination, two or more compounds selected from each category of the compound (1) or the salt of the compound (1) may be used. It can also be used.

  One or more compounds selected from the group consisting of the compound (1) and the salt of the compound (1) (hereinafter simply referred to as “black dye (1)”) are 0 in the black aqueous ink composition of the present invention. 0.5 to 12% by weight is preferably contained, and 1.0 to 9.0% by weight is more preferred. When the content of the black dye (1) in the ink composition is 0.5% by weight or more, when an image or the like is recorded on a recording medium using the ink composition, sufficiently good color development and high image density are obtained. Can be obtained. Further, by setting the content of the black dye (1) in the ink composition to 12% by weight or less, the viscosity of the ink composition can be adjusted to a preferable value, and the ink composition from the inkjet head can be adjusted. The discharge amount can be stabilized, and clogging of the ink jet head can be prevented.

The ink composition of the present invention is characterized by containing at least one compound capable of including the black dye together with the black dye.
In the present invention, the “compound capable of inclusion of a black dye” is a compound that can incorporate a black dye molecule into its structure, and the molecule of this compound forms a tunnel shape, or a layered or three-dimensional network structure ( This is called an inclusion grid), and the fact that a black dye molecule enters the gap is called inclusion.

Compounds that can include black dyes that can be used in the present invention include cyclodextrins, crown ethers, steroids, calixarenes, rotaxanes, molecular nanotubes, cyclophane, azacyclophane, cyclotriveratrilene , Sfend, cavitand, oligopeptide, deoxycholic acid, perhydrotriphenylene, tri-O-thymoted, cyclophosphazene compounds, and the like, and cyclodextrins are particularly preferable.
Examples of cyclodextrins include cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, and derivatives of these cyclodextrins. Among these, cyclodextrins are preferable. Cyclodextrin and its derivatives are preferred. When α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are compared, the effect is higher in the order of α, β, and γ.
By including the compound capable of inclusion of the black dye as described above in the ink composition of the present invention, the black dye molecule is incorporated into the compound capable of inclusion, and the contact probability between the black dye molecule and ozone is increased. It is considered that the ozone resistance was further improved.

The content of the compound capable of including the black dye in the ink composition is preferably 0.1 to 30% by weight, and more preferably 1 to 20% by weight. When the content is 0.1% by weight or more, an effect of improving ozone resistance is exhibited, and when the content is 30% by weight or less, the viscosity of the ink composition can be adjusted to a preferable value.
The black dye can be included with at least one selected from the group consisting of the compound represented by the above formula (1) and the salt of the compound represented by the above formula (1) to be contained in the black aqueous ink composition. The weight ratio of the compounds is preferably 3: 1 to 1: 5, more preferably 2: 1 to 1: 3. By containing the compound capable of inclusion of the black dye in the above ratio, the ozone resistance in the printed matter of the black aqueous ink composition can be improved.
The effect produced by the compound capable of including the black dye is obtained when printed on any medium, but is particularly effective in combination with a mat-type medium.

The black ink composition of the present invention preferably uses water or a mixture of water and a water-soluble organic solvent as the main solvent.
As water, ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or the like can be used. From the viewpoint of long-term storage, water subjected to various chemical sterilization treatments such as ultraviolet irradiation and hydrogen peroxide addition is preferable. The content of water when used as the main solvent is preferably 40 to 90% by weight, more preferably 50 to 80% by weight, based on the total weight of the ink composition.

  The ink composition of the present invention may further contain a humectant selected from water-soluble organic solvents and / or saccharides having a vapor pressure lower than that of pure water. By including the humectant, the ink can be moisturized by suppressing evaporation of moisture in the ink jet recording system. In addition, if it is a water-soluble organic solvent, the ejection stability can be improved, and the viscosity can be easily changed without changing the ink characteristics.

The water-soluble organic solvent refers to a medium having an ability to dissolve a solute, and is selected from organic and water-soluble solvents having a vapor pressure smaller than that of water. Preferred specific examples include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, 1,5-propanediol, 1,2-hexanediol, 1,2,6-hexanetriol. Polyhydric alcohols such as glycerin; ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl Glycol ethers such as ether; formamide, dimethylformamide, 1,3 Dimethyl-2-imidazolidinone, 2-pyrrolidone, N- methyl-2-nitrogen-containing solvents pyrrolidone; thiodiglycol, sulfur-containing solvents such as dimethyl sulfoxide.
Examples of the saccharide include glucose, mannose, fructose, galactose, maltose, sucrose, maltitol, sorbitol, and gluconolactone.
The humectant is preferably added in an amount of 5 to 50% by weight, more preferably 5 to 30% by weight, and still more preferably 5 to 20% by weight with respect to the total amount of the ink composition. If it is 5% by weight or more, moisture retention can be obtained, and if it is 50% by weight or less, it is easy to adjust the viscosity used for inkjet recording.

In addition, the black ink composition of the present invention contains a nonionic surfactant as an additive that is effective for maintaining quickness (penetration) of the ink and maintaining the roundness of one dot. It is preferable.
Examples of nonionic surfactants used in the present invention include acetylene glycol surfactants. As the acetylene glycol surfactant used in the present invention, it is particularly preferable to use a compound represented by the following formula (10).

(In the formula (10), R ¹ , R ² , R ³ , and R ⁴ each independently represent a C1-C6 straight chain, cyclic, or branched alkyl chain, and A ¹ O and A ² O Are each independently a C2-C3 oxyalkylene chain, such as oxyethylene or oxypropylene, or a polyoxyalkylene chain obtained by polymerization or copolymerization of C2-C3 alkylene oxide, such as a polyoxyethylene chain, polyoxypropylene In the formula (10), n and m represent A ¹ O or A ² O units, that is, the number of oxyalkylene repeats, and 0 ≦ n <30, 0 ≦ m < 30 and 0 ≦ n + m <50.)

  Specific examples of such acetylene glycol surfactants include Surfinol 465, Surfinol 104 (above, Air Products and Chemicals, Inc., trade name (USA)), Olphine STG, Olphine E1010 (above, Japan). Shinken Chemical Co., Ltd., trade name). The amount added is preferably 0.1 to 5% by weight, more preferably 0.5 to 2% by weight, based on the total amount of the ink composition. When the addition amount is 0.1% by weight or more, sufficient penetrability can be obtained, and when the addition amount is 5% by weight or less, it is easy to prevent the occurrence of image bleeding.

Furthermore, by adding a glycol ether aqueous organic solvent as a penetration accelerator in addition to a nonionic surfactant, the permeability is further increased and the boundary between adjacent color inks when color printing is performed is increased. Bleed is reduced and a very clear image can be obtained.
Examples of the glycol ether aqueous organic solvent that can be used in the present invention include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, propylene glycol monobutyl ether, diethylene glycol Examples include propylene glycol monobutyl ether and triethylene glycol monobutyl ether. The addition amount is preferably 3 to 30% by weight, more preferably 5 to 15% by weight, based on the total amount of the ink composition. If the added amount is 3% by weight or more, the effect of preventing bleeding can be obtained. Further, if it is 30% by weight or less, the image does not bleed and oily separation does not occur, so that a dissolution aid for these glycol ether aqueous organic solvents is unnecessary, and the viscosity of the ink is increased by the dissolution aid. The ink jet head can discharge well.

Furthermore, the ink composition of the present invention includes, as necessary, a water-soluble polymer such as sodium alginate, a water-soluble resin, a fluorosurfactant, an antiseptic, an antifungal agent, a rust preventive, a dissolution aid, an oxidizing agent. An inhibitor or the like may be added.
Examples of preservatives or antifungal agents include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazolin-3-one (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN (trade name) manufactured by AVECIA) and the like.
Furthermore, examples of dissolution aids or antioxidants include metal hydroxides such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, quaternary ammonium hydroxides (tetramethylammonium, etc.), etc. Ammonium salts, carbonates such as potassium carbonate, sodium carbonate, lithium carbonate, and other phosphates, or ureas such as urea, thiourea and tetramethylurea, allophanates such as allophanate and methyl allophanate, biuret, dimethylbiuret, Biurets such as tetramethyl biuret can be mentioned.
In the black ink composition of the present invention, the above-mentioned optional components can be used alone or in a mixture of plural types selected within each group and between groups.
In the black ink composition of the present invention, the amount of all the components of the ink composition is preferably selected so that the viscosity of the ink composition is less than 10 mPa · s at 20 ° C.
Further, the surface tension of the black ink composition of the present invention is preferably 45 mN / m or less at 20 ° C., more preferably 25 to 45 mN / m.

  The ink composition of the present invention preferably has a pH of 10.5 or less at 20 ° C., more preferably 8.5 or less. By setting the pH of the ink composition at 20 ° C. to 10.5 or less, it is possible to prevent deterioration of various members that come into contact with the ink composition, such as members constituting an ink cartridge or an ink jet head. It is easy to suppress the decomposition of the colorant in the ink composition.

  In the present invention, it is preferable to adjust the pH of the ink composition at 20 ° C. to a preferred value by adding a pH adjuster to the ink composition. Examples of the pH adjuster that can be used in the present invention include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and amines such as triethanolamine, diethanolamine, and tripropanolamine. It is preferable to use it. Moreover, pH buffer agents, such as a good buffer, can also be used as needed. The addition amount of the pH adjusting agent to the ink composition is an amount that allows the pH of the ink composition to fall within the above-described preferable range, and the amount can be appropriately determined for each ink composition. The pH value of the ink composition in the present invention is a value measured by directly inserting a pH electrode into the ink composition using a commercially available pH meter.

  In order to prepare the ink composition of the present invention, for example, each component to be contained in the ink composition is sufficiently mixed to obtain a uniform solution, and then a membrane filter having an average aperture of 0.8 μm is used. A method of degassing under reduced pressure after filtration under pressure can be used.

  The black aqueous ink composition of the present invention can be used for general writing instruments, recorders, pen plotters, and the like, but is particularly preferably used for an ink jet recording method. The ink jet recording method in which the black ink composition of the present invention can be used includes any recording method in which the ink composition is ejected as droplets from a thin nozzle and the liquid suitability is adhered to a recording medium. Specific examples of the ink jet recording method in which the ink composition of the present invention can be used will be described below.

  The first method is a method called an electrostatic attraction method. In the electrostatic suction method, a strong electric field is applied between the nozzle and the acceleration electrode arranged in front of the nozzle, and droplet-like ink is continuously ejected from the nozzle, and the ink droplet passes between the deflection electrodes. In the meantime, by applying a printing information signal to the deflection electrode, the ink droplets are blown toward the recording medium and the ink is fixed on the recording medium, or an image is recorded without deflecting the ink droplets. In this method, an image is fixed on a recording medium by ejecting ink droplets from a nozzle onto the recording medium in accordance with a print information signal. The ink composition of the present invention is preferably used in a recording method using this electrostatic suction method.

  The second method is a method for forcibly ejecting ink droplets from the nozzles by applying pressure to the ink liquid with a small pump and mechanically vibrating the ink jet nozzles with a quartz vibrator or the like. The ink droplet ejected from the nozzle is charged at the same time as it is ejected, and while the ink droplet passes between the deflection electrodes, a print information signal is given to the deflection electrode to fly the ink droplet toward the recording medium, This is a method for recording an image on a recording medium. The ink composition of the present invention is preferably used in this recording method.

  The third method is a method in which an image is recorded on a recording medium by simultaneously applying a pressure and a printing information signal to the ink liquid by a piezoelectric element, and ejecting ink droplets from a nozzle toward the recording medium. The ink composition of the present invention is preferably used in this recording method.

  In the fourth method, the ink liquid is heated and foamed using microelectrodes according to the print signal information, and the bubbles are expanded to eject the ink liquid from the nozzle toward the recording medium, thereby forming an image on the recording medium. It is a method of recording. The ink composition of the present invention is preferably used in this recording method.

  The black aqueous ink composition of the present invention is particularly preferable as an ink composition used when an image is recorded on a recording medium using an image recording method based on an ink jet recording method including the four methods described above. The recorded matter recorded using the black aqueous ink composition of the present invention has an excellent image quality, is excellent in light resistance, album storage resistance, and moisture resistance, and has very high ozone resistance.

  EXAMPLES The present invention will be described more specifically based on examples below, but the present invention is not limited to the following examples.

[Preparation of black aqueous ink composition]
Based on the composition shown in Table 1 below, each component was mixed to obtain a uniform solution, and the resulting solution was pressure filtered using a membrane filter having an average opening diameter of 0.8 μm to obtain an ink composition. Obtained. The pH of each ink composition was a value measured at 20 ° C. using a pH meter (MODEL PH82 manufactured by Yokogawa Electric Corporation), and all were 8.4. In Table 1, the numerical value of each component indicates the weight% of each component when the mass of the ink composition is 100%.

Table 1 shows the compositions of the ink compositions used in Examples 1 to 3 and Comparative Example 1.

で表される化合物のリチウム塩である。 The dyes used in Examples 1 to 3 and Comparative Example 1 are represented by the following formula (3):

It is a lithium salt of the compound represented by these.

[Ozone resistance test]
Each of the above inks is filled into a cartridge dedicated to the black ink of the printer PM-950C, and photographic paper <gloss> (trade name, manufactured by Seiko Epson Corporation, model number: KA450PSK) and photo matte paper (trade name, manufactured by Seiko Epson Corporation) , Model number: KA450PM). For printing, a solid print sample was used.
Using the Ozone Weather Meter OMS-H type (trade name, manufactured by Suga Test Instruments Co., Ltd.) under the conditions of a temperature of 24 ° C., a humidity of 60% RH, and an ozone concentration of 10 ppm, Exposure to ozone for 48 or 96 hours. Using a reflection densitometer Spectrolino (trade name, manufactured by GRETAG), the OD value (Optical Density) of the recorded material before and after ozone exposure was measured. The measurement was performed under the conditions that the light source was D50, no light source filter, absolute white was used as a white standard, and the viewing angle was 2 °. The following calculation formula (1):
ROD (%) = (D _n / D _o ) × 100 (where D _n is the OD value of the image after completion of the ozone exposure test, D _o is the OD value of the image before the start of the ozone exposure test) (calculation formula 1 )
Using the obtained measurement value (OD value), the optical density residual ratio (ROD) of the image of each recorded matter after ozone exposure was obtained by calculation.

  Based on the obtained ROD, the ozone resistance of the recorded material was evaluated by ranking the test results A to D using the following criteria. Tables 2 and 3 show the evaluation results and evaluation criteria.

It can be seen that the ink compositions of Examples 1 to 3 have superior ozone resistance compared to the ink composition of Comparative Example 1 that does not use a compound capable of including a black dye. Among cyclodextrins using black dyes as inclusion compounds in the examples, α-cyclodextrin (Example 1) is most effective, followed by β-cyclodextrin (Example 2), γ-cyclodextrin ( Example 3).

Claims (14)

A black aqueous ink composition containing at least one selected from the group consisting of a compound represented by the following formula (1) and a salt of the compound represented by the formula (1) as a black dye, wherein the black dye is A black aqueous ink composition comprising at least one compound capable of inclusion.

(In the formula (1), R ¹ represents a phenyl group having a substituent or a naphthyl group having a substituent, R ² represents a phenylene group having a substituent or a naphthylene group having a substituent, and R ³ is at least It represents a 5- to 7-membered heterocyclic group having one double bond and a substituent, and the substituent in R ^{1 to} R ³ is independently OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NO ₂ , NH ₂ , a C1-4 alkyl group, a substituted alkyl group, a C1-4 alkoxy group, a substituted alkoxy group, an amino group, a substituted amino group, and a substituent Selected from the group consisting of phenyl groups having  2. The black aqueous ink composition according to claim 1, wherein the black aqueous ink composition contains 0.1 to 30% by weight of a compound capable of including the black dye. 3.  In the black aqueous ink composition, a compound capable of including the black dye and at least one selected from the group consisting of a compound represented by the formula (1) and a salt of the compound represented by the formula (1) The black water-based ink composition according to claim 1, wherein the weight ratio is 3: 1 to 1: 5.   The black aqueous ink composition according to claim 1, wherein the compound capable of including the black dye is cyclodextrin.   The black aqueous ink composition according to claim 4, wherein the cyclodextrin is α-cyclodextrin. The black water-based ink composition according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (2).

(In the formula (2), R ^{1 to} R ⁹ independently represent a group selected from the group consisting of H, OH, SO ₃ H, PO ₃ H ₂ , CO ₂ H, NO ₂ , and NH _2. .)   The black aqueous ink composition according to any one of claims 1 to 6, wherein the black dye is contained in the black aqueous ink composition in an amount of 0.5 to 12% by weight.   The black aqueous ink composition according to claim 1, wherein the black aqueous ink composition contains an acetylene glycol surfactant.   The black aqueous ink composition according to any one of claims 1 to 8, wherein the black aqueous ink composition contains a glycol ether-based aqueous organic solvent.   The black aqueous ink composition according to claim 1, wherein the pH of the ink composition at 20 ° C. is 10.5 or less.   The black aqueous ink composition according to any one of claims 1 to 10, which is used in an inkjet recording method.   The black aqueous ink composition according to claim 11, wherein the inkjet recording method is a recording method using an inkjet head that forms ink droplets by mechanical deformation of an electrostrictive element.   An inkjet recording method for performing recording by discharging droplets of an ink composition and attaching the droplets to a recording medium, wherein the black aqueous ink according to any one of claims 1 to 12 is used as the ink composition. An ink jet recording method comprising using the composition. A recorded matter recorded using the black aqueous ink composition according to any one of claims 1 to 12, or recorded by the recording method according to claim 13.