Inkjet ink set

Abstract

This invention provides an inkjet ink set that enables the simultaneous reproduction of excellent black and light black colors while producing printed materials with superior granularity and colorfastness. [Solution] The ink set comprises a black inkjet ink composition and a light black inkjet ink composition. The black ink composition comprises one or more dyes selected from the group consisting of a first dye having a naphthalene skeleton and not containing chromium or copper, with a hue angle ∠h° of 270° or more and 290° or less for the printed material, a second dye having a naphthalene skeleton and not containing chromium or copper, with a hue angle of 35° or more and 55° or less for the printed material, and a third dye having a pyrazole skeleton and not containing chromium or copper, with a hue angle of 345° or more and 359° or less for the printed material, and water. The light black ink composition comprises a fourth dye having an anthraquinone skeleton and not containing chromium or copper, with a hue angle of 230° or more and 280° or less for the printed material, and one or more dyes selected from the group consisting of the second dye and the third dye, and water.

Description

[Technical Field]

[0001] This invention relates to an inkjet ink set. [Background technology]

[0002] Acid dye black inks used for dyeing fabrics containing animal fibers such as wool and silk, and amide fibers such as nylon, are widely used, as described in Patent Document 1. These include CIAcid Black 172, and other inks such as CIAcid Black 52:1 and CIAcid Black 194. Although these inks all contain chromium, their use has been restricted recently due to safety and environmental concerns. Therefore, there is a growing trend to replace acid dye black inks with inks that do not contain metals such as chromium. One example of such a black ink is CIAcid Blue 113. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-48107 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, while CIAcid Blue 113 can reproduce a relatively dark navy blue, it cannot reproduce a good black color on its own, and the prints also lack colorfastness. Therefore, to reproduce black, inks composed of CIAcid Blue 113 and multiple other colors are used, but such inks have poor granularity and colorfastness in the prints, which presents a challenge in meeting market demands. Furthermore, while inkjet inks typically reproduce light black colors using the same ink as the black ink, inks composed of CIAcid Blue 113 and multiple other colors cannot reproduce light black colors, resulting in inferior fastness and granularity of the printed material. Therefore, in the inkjet ink method, there is a need for an ink set that can reproduce both excellent black and light black colors simultaneously, while the printed material exhibits superior granularity and fastness. [Means for solving the problem]

[0005] The inkjet ink set of the present invention comprises a black inkjet ink composition and a light black inkjet ink composition, wherein the black ink composition comprises one or more selected from the group consisting of a first dye having a naphthalene skeleton, not containing chromium and copper, and having a hue angle ∠h° of 270° or more and 290° or less for the printed material, a second dye having a naphthalene skeleton, not containing chromium and copper, and having a hue angle ∠h° of 35° or more and 55° or less for the printed material, and a third dye having a pyrazole skeleton, not containing chromium and copper, and having a hue angle ∠h° of 345° or more and 359° or less for the printed material, and water, wherein the light black ink composition comprises a fourth dye having an anthraquinone skeleton, not containing chromium and copper, and having a hue angle ∠h° of 230° or more and 280° or less for the printed material, one or more selected from the group consisting of the second dye and the third dye, and water. [Brief explanation of the drawing]

[0006] [Figure 1] An example of an inkjet recording method is a flowchart. [Figure 2] Table 1 shows the compositions of the black inkjet ink composition and the light black inkjet ink composition. [Figure 3] Table 2 shows the evaluation results. [Modes for carrying out the invention]

[0007] The following describes in detail an embodiment of the present invention (hereinafter referred to as "this embodiment"), but the present invention is not limited thereto, and various modifications are possible without departing from its essence.

[0008] 1. Inkjet ink set The inkjet ink set of this embodiment (hereinafter also simply referred to as "ink set") comprises a black inkjet ink composition (hereinafter also simply referred to as "black ink composition") and a light black inkjet ink composition (hereinafter also simply referred to as "light black ink composition"), The black ink composition comprises one or more dyes selected from the group consisting of a first dye (hereinafter also simply referred to as "first dye") having a naphthalene skeleton, not containing chromium or copper, and having a hue angle ∠h° of 270° or more and 290° or less for the printed material; a second dye (hereinafter also simply referred to as "second dye") having a naphthalene skeleton, not containing chromium or copper, and having a hue angle ∠h° of 35° or more and 55° or less for the printed material; and a third dye (hereinafter also simply referred to as "third dye") having a pyrazole skeleton, not containing chromium or copper, and having a hue angle ∠h° of 345° or more and 359° or less for the printed material; and water. The light black ink composition comprises a fourth dye (hereinafter also simply referred to as "the fourth dye") having an anthraquinone skeleton, not containing chromium or copper, and having a hue angle ∠h° of 230° or more and 280° or less for the printed material, one or more selected from the group consisting of the second dye and the third dye, and water.

[0009] According to this embodiment, an ink set can be obtained comprising a black ink composition having excellent blackness, granularity, and fastness, and a light black ink composition having excellent light blackness, granularity, and fastness. Therefore, by using the black ink composition and the light black ink composition in an inkjet ink method, it becomes possible to reproduce both excellent black and light black colors simultaneously while the printed material has excellent granularity and fastness.

[0010] Although the reason why this embodiment yields such excellent results is not entirely clear, the inventors of the present invention surmise the following.

[0011] That is, the black ink composition according to the present embodiment includes at least one selected from the group consisting of a first dye having a naphthalene skeleton, not containing chromium and copper, and having a hue angle ∠h° of the dyed product of 270° or more and 290° or less, a second dye having a naphthalene skeleton, not containing chromium and copper, and having a hue angle ∠h° of the dyed product of 35° or more and 55° or less, and a third dye having a pyrazole skeleton, not containing chromium and copper, and having a hue angle ∠h° of the dyed product of 345° or more and 359° or less, and water. In the black ink composition, together with the first dye having a specific hue angle that reproduces a relatively dark navy color, as a complementary color component, it includes at least one selected from the group consisting of the second dye having a specific hue angle and the third dye having a specific hue angle. Therefore, the obtained dyed product can reproduce good black with a small number of dye species. And because the number of dye species is small, the dyed product can have excellent granularity. Moreover, since the first to third dyes have specific structures, these dyes can aggregate preferably. Therefore, the dyed product can obtain excellent fastness.

[0012] In addition, the light black ink according to the present embodiment includes at least one selected from the group consisting of a fourth dye having an anthraquinone skeleton, not containing chromium and copper, and having a hue angle ∠h° of the dyed product of 230° or more and 280° or less, the second dye not containing chromium and copper and having a hue angle ∠h° of the dyed product of 35° or more and 55° or less, and the third dye having a pyrazole skeleton, not containing chromium and copper, and having a hue angle ∠h° of the dyed product of 345° or more and 359° or less, and water. In the light black ink composition, together with the fourth dye having a specific hue angle that reproduces light black, as a complementary color component, it includes at least one selected from the group consisting of the second dye having a specific hue angle and the third dye having a specific hue angle. Therefore, the obtained dyed product can reproduce good light black with a small number of dye species. And because the number of dye species is small, the dyed product can have excellent granularity. Moreover, since the second to fourth dyes have specific structures, these dyes can aggregate preferably. Therefore, the dyed product can obtain excellent fastness.

[0013] Thus, the ink set has a black ink composition having excellent black color, granularity, and fastness, and a light black ink composition having excellent light black color, granularity, and fastness. Therefore, according to this embodiment, in the inkjet ink method, by using the black ink composition and the light black ink composition, it is possible to simultaneously reproduce excellent black and light black colors while the dyed product has excellent granularity and fastness. However, the reason is not limited to this.

[0014] Next, each component contained in the black ink composition and the light black ink composition will be described.

[0015] 1.1. Black ink composition 1.1.1. First dye The black ink composition contains a first dye having a naphthalene skeleton, not containing chromium and copper, and having a hue angle ∠h° of the dyed product of 270° or more and 290° or less. By using the first dye in the black ink composition together with the second dye and / or the second dye, a black ink composition having excellent black color, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, an ink set capable of simultaneously reproducing excellent black and light black colors while the dyed product has excellent granularity and fastness can be preferably obtained. The first dye may be used alone or in combination of two or more.

[0016] The first dye has a naphthalene skeleton in its structure. Since the first dye has such a specific structure, it can preferably aggregate with the second dye and the third dye. Therefore, it is possible to obtain excellent fastness for the dyed product obtained by using a black ink composition containing such a dye.

[0017] The first dye does not contain chromium and copper. Therefore, by using the first dye, the safety is high and the environmental load can also be reduced.

[0018] In this specification, "not containing chromium and copper" means that the contents of chromium and copper in the dye are less than or equal to the amount of inevitable impurities. Specifically, the contents of chromium and copper in the dye are each 1 ppb or less.

[0019] The hue angle ∠h° of the printing of the first dye is 270° or more and 290° or less. Therefore, the first dye can reproduce a relatively dark dark blue color. Further, by using the first dye together with the second dye and / or the third dye, which are complementary color components, the printed matter can reproduce good black with a small number of dye species. Moreover, since the number of dye species is small, the printed matter can have excellent granularity.

[0020] The hue angle ∠h° of the printing of the first dye is preferably 275° or more and 285° or less. When the hue angle ∠h° is within the above range, the printed matter can reproduce better black and can have more excellent granularity.

[0021] In this specification, the hue angle ∠h° of the printed matter is defined in the CIELAB color space on the printed matter after printing. Here, the CIELAB color space is an approximate uniform color space recommended by the Commission Internationale de l'Eclairage (abbreviation: CIE) in 1976, and the commission refers to this as CIE1976 (L * a * b * ).

[0022] Further, the hue angle ∠h° is ∠h° = tan -1 (b * / a * ) + 180 (when a * < 0), or ∠h° = tan -1 (b * / a * ) + 360 (when a * > 0). a * and b * represent the perceptual chromaticity indices defined in the CIELAB color space.

[0023] In this specification, the hue angle ∠h° of a printed material is defined as the whiteness L of the recording medium. * This is the hue angle ∠h° measured from the color on a recording medium printed using a polyester fabric with a hue value of 85-95, by performing a dry heat transfer at a temperature of 180-210°C for 30-120 seconds. More specifically, it is a value measured by the following test method.

[0024] An inkjet printer (Seiko Epson Corporation, product name "PX-G930") is filled with dye to form an image on transfer paper (Sappi Corporation, product name "Transjet Sportsline"). Specifically, with a resolution of 720 dpi horizontally and 720 dpi vertically, and an ink output of 100% duty cycle, the ink injection rate is 12 mg / inch. 2 A fill pattern that can be recorded under these conditions is created and used.

[0025] Next, the recording surface of the transfer paper on which the image is formed and a white polyester fabric (manufactured by Toray Industries, Inc., product name "SS-755 K-1", whiteness L) are placed. * With the values ​​85-95 facing each other, a heat press (manufactured by Taiyo Seiki Co., Ltd., product name "TP-608M") is used to press at a temperature of 180-210°C for 30-120 seconds at a rate of 4.2 N / cm². 3 It is heat-transferred using pressure.

[0026] The obtained evaluation samples were determined using a spectrophotometer (product name "FD-7", manufactured by Konica Minolta, Inc., measurement conditions: light source D65, filter D65, φ2 degrees). * value, b * From the value, the hue angle is ∠h° and the lightness is L. * The whiteness L of the polyester fabric is calculated. * Similarly, measurements are taken using a spectrophotometer (product name "FD-7", manufactured by Konica Minolta, Inc., measurement conditions: light source D65, filter D65, φ2 degrees).

[0027] One example of a first dye is CIAcid Blue 113.

[0028] The first dye preferably contains CIAcid Blue 113. CIAcid Blue 113, when used with a smaller number of dyes, along with the second and / or third dyes, allows the printed material to reproduce a better black color and exhibit superior granularity. Furthermore, because CIAcid Blue 113 aggregates more favorably with the second and / or third dyes, the printed material can achieve superior color fastness.

[0029] The content of the first dye is preferably 0.5% by mass or more and 20.0% by mass or less, more preferably 1.0% by mass or more and 15.0% by mass or less, and even more preferably 2.0% by mass or more and 10.0% by mass or less, relative to the total amount of the black ink composition. By using a first dye with a content within the above range together with a second dye and / or the second dye, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with a light black ink composition, an ink set can be suitably obtained in which the printed material has superior granularity and fastness while simultaneously reproducing superior black and light black.

[0030] 1.1.2. Second dye and third dye The black ink composition contains one or more dyes selected from the group consisting of a second dye having a naphthalene skeleton, not containing chromium or copper, and having a hue angle ∠h° of 35° to 55° for the printed material, and a third dye having a pyrazole skeleton, not containing chromium or copper, and having a hue angle ∠h° of 345° to 359° for the printed material. By including the second dye and / or the third dye together with the first dye, a black ink composition with excellent blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, an ink set can be suitably obtained in which the printed material has excellent granularity and fastness while simultaneously reproducing excellent black and light black. The second dye may be used alone or in combination of two or more. The third dye may be used alone or in combination of two or more.

[0031] • Second dye The second dye has a naphthalene skeleton in its structure. Having such a specific structure allows the second dye to aggregate suitably with the first dye and, optionally, a third dye. Therefore, printed materials obtained using a black ink composition containing such dyes can exhibit excellent colorfastness.

[0032] The second dye does not contain chromium or copper. Therefore, using the second dye results in higher safety and a reduced environmental impact.

[0033] The second dye has a hue angle ∠h° of 35° to 55° for the printed material. Therefore, the second dye can reproduce a relatively dark orange color. Furthermore, by using the second dye as a complementary color component to the first dye, along with the third dye as needed, the printed material can reproduce a good black color with fewer dye types. Moreover, because fewer dye types are used, the printed material can have excellent granularity.

[0034] The second dye preferably has a hue angle ∠h° of 40° or more and 50° or less in the printed material. By using the second dye, whose hue angle ∠h° is within the above range, as the complementary color component of the first dye, along with a third dye as needed, the printed material can reproduce a better black color and have a superior granular texture.

[0035] A second dye is, for example, CIAcid Orange 94.

[0036] The second dye preferably contains CIAcid Orange 94. By using CIAcid Orange 94 together with the first dye and, if necessary, the third dye, the printed material can reproduce a better black color with fewer dye types and have superior granularity. Furthermore, since CIAcid Orange 94 aggregates more favorably with the first dye and, if necessary, the third dye, the printed material can obtain superior color fastness.

[0037] The content of the second dye is preferably 0.5% to 20.0% by mass, more preferably 1.0% to 15.0% by mass, and even more preferably 2.0% to 10.0% by mass, relative to the total amount of the black ink composition. By using the second dye, whose content is within the above range, as a complementary color component to the first dye, along with a third dye as needed, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black simultaneously, while the printed material has superior granularity and fastness.

[0038] • Third dye The third dye has a pyrazole skeleton in its structure. Having such a specific structure allows the third dye to suitably aggregate with the first dye and, optionally, the second dye. Therefore, printed materials obtained using a black ink composition containing such dyes can exhibit excellent colorfastness.

[0039] The third dye does not contain chromium or copper. Therefore, using this third dye offers higher safety and reduces the environmental impact.

[0040] The third dye has a hue angle ∠h° of 345° to 359° for the printed material. Therefore, the third dye can reproduce a relatively dark yellow. Furthermore, by using the third dye as a complementary color component to the first dye, together with the second dye as needed, the printed material can reproduce a good black color with fewer dye types. Moreover, because fewer dye types are used, the printed material can have excellent granularity.

[0041] The third dye is preferably one whose hue angle ∠h° of the printed material is between 348° and 355°. By using the third dye, whose hue angle ∠h° is within the above range, as the complementary color component of the first dye, along with the second dye as needed, the printed material can reproduce a better black color and have a superior granular texture.

[0042] A third dye is, for example, CIAcid Yellow 79.

[0043] The third dye preferably contains CIAcid Yellow 79. By using CIAcid Yellow 79 together with the first dye and, if necessary, the second dye, the printed material can reproduce a better black color with fewer dye types and have superior granularity. Furthermore, since CIAcid Yellow 79 aggregates more favorably with the first dye and, if necessary, the second dye, the printed material can obtain superior color fastness.

[0044] The content of the third dye is preferably 0.5% to 20.0% by mass, more preferably 1.0% to 15.0% by mass, and even more preferably 2.0% to 10.0% by mass, relative to the total amount of the black ink composition. By using a third dye with a content within the above range as a complementary color component of the first dye, along with a second dye as needed, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with a light black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black simultaneously, while the printed material has superior granularity and fastness.

[0045] 1.1.3.Water The black ink composition contains water. Examples of suitable water include pure water such as deionized water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water from which ionic impurities have been removed as much as possible. Furthermore, water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide is preferred because it can suppress the growth of mold and bacteria when the ink composition is stored for a long period of time.

[0046] The water content is preferably 30.0% by mass or more and 80.0% by mass or less relative to the total amount of the black ink composition. When the water content is within this range, an increase in the viscosity of the black ink composition can be suppressed.

[0047] 1.1.4. Water-soluble organic solvents The black ink composition preferably contains a water-soluble organic solvent. Functions of the water-soluble organic solvent include, for example, mitigating the water absorption behavior of the recording medium, improving the wettability of the black ink composition to the recording medium, and enhancing the moisture retention of the black ink composition. The water-soluble organic solvent can be used individually or in combination of two or more types.

[0048] Examples of water-soluble organic solvents include water-soluble esters, alkylene glycol ethers, cyclic esters, nitrogen-containing solvents, and alcohols. Examples of nitrogen-containing solvents include water-soluble cyclic amides and acyclic amides. Examples of acyclic amides include water-soluble alkoxyalkylamides.

[0049] Examples of esters include glycol monoacetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate, as well as ethylene glycol diacetate and diethylene glycol monobutyl ether acetate. Examples of glycol diesters include glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, and dipropylene glycol acetate propionate.

[0050] Examples of alkylene glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, and tripropylene Examples include alkylene glycol monoalkyl ethers such as glycol monobutyl ether, and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0051] Examples of cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen atoms of the methylene group adjacent to the carbonyl group are substituted with alkyl groups having 1 to 4 carbon atoms.

[0052] Examples of alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, and 3-n-propoxy Examples include -N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso-propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, and 3-tert-butoxy-N,N-methylethylpropionamide.

[0053] Examples of cyclic amides include lactams, and more specifically, pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone.

[0054] Examples of alcohols include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, tert-pentanol, ethylene glycol, propylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, diethylene glycol, dipropylene glycol, triethylene glycol, 1,3-propanediol, Examples include 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, trimethylolpropane, and glycerin.

[0055] The water-soluble organic solvent preferably contains one or more selected from the group consisting of glycerin and triethylene glycol monobutyl ether. By using the above water-soluble organic solvent, a black ink composition can be obtained that has better storage stability and superior blackness, granularity, and fastness. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black simultaneously, while the printed material has superior granularity and fastness.

[0056] The content of the water-soluble organic solvent is preferably 0.1% to 40% by mass, more preferably 5.0% to 30% by mass, and even more preferably 10% to 25% by mass, based on the total amount of the black ink composition. When the content of the water-soluble organic solvent is within the above range, the black ink composition can be made to have better storage stability and to obtain a black ink composition with better black color, granularity, and fastness. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, it is possible to suitably obtain an ink set that can reproduce both better black and light black simultaneously, while the printed material has better granularity and fastness.

[0057] 1.1.5. Surfactants The black ink composition preferably contains a surfactant. The surfactant has the function of lowering the surface tension of the black ink composition and adjusting its wettability with the recording medium. The surfactant may be used alone or in combination of two or more types.

[0058] Examples of surfactants include acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants.

[0059] Examples of acetylene glycol-based surfactants include Surfinol (registered trademark) 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, DF110D (manufactured by Nisshin Chemical Industry Co., Ltd.); Olfin (registered trademark) Trademarks include B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP.4001, EXP.4036, EXP.4051, AF-103, AF-104, AK-02, SK-14; AE-3 (manufactured by Nisshin Chemical Industry Co., Ltd.); Acetylenel (registered trademark) E00, E00P, E40, E100 (manufactured by Kawaken Fine Chemical Co., Ltd.).

[0060] Examples of silicone-based surfactants include polysiloxane compounds such as polyether-modified organosiloxanes. Examples of commercially available polyether-modified organosiloxanes include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (manufactured by BIC Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6004, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0061] Examples of fluorinated surfactants include fluorine-modified polymers. For example, BYK-340 (manufactured by Bic Chemie Japan Co., Ltd.) is one such example.

[0062] Preferably, the surfactant includes an acetylene glycol-based surfactant. By using the above-mentioned surfactant, the surface tension of the black ink composition can be further reduced, allowing for better adjustment of the wettability with the recording medium.

[0063] The surfactant content is preferably 0.01% to 10% by mass, and more preferably 0.05% to 5.0% by mass, relative to the total amount of the ink composition. When the surfactant content is within the above range, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black simultaneously, while the printed material has superior granularity and fastness.

[0064] 1.1.6. Amines The black ink composition may contain amines. The amines may function as pH adjusters. The amines may be used individually or in combination of two or more.

[0065] Examples of amines include diethanolamine, triethanolamine, and triisopropanolamine.

[0066] The amine content is preferably 0.01% to 10% by mass, and more preferably 0.05% to 5.0% by mass, relative to the total amount of the black ink composition. When the amine content is within the above range, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black simultaneously, while the printed material has superior granularity and fastness.

[0067] 1.1.7.Ureas The black ink composition may contain ureas. Ureas tend to function as humectants and dyeing aids that improve the dye adhesion of the black ink composition. Ureas may be used alone or in combination of two or more types.

[0068] Examples of ureas include urea, ethyleneurea, tetramethylurea, thiourea, and 1,3-dimethyl-2-imidazolidinone.

[0069] The urea content is preferably 0.1% by mass or more and 10% by mass or less relative to the total amount of the black ink composition. When the urea content is within the above range, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, it is possible to suitably obtain an ink set that can reproduce both superior black and light black simultaneously, while the printed material has superior granularity and fastness.

[0070] 1.1.8. Other Ingredients The black ink composition may also contain various additives that are commonly used in ink compositions, other than the components mentioned above, such as sugars, preservatives, fungicides, solubilizers, viscosity modifiers, pH adjusters, antioxidants, ultraviolet absorbers, oxygen absorbers, rust inhibitors, corrosion inhibitors, and chelating agents. Additives may be used individually or in combination of two or more.

[0071] The additive content is preferably 0.01% by mass or more and 10.0% by mass or less in total, relative to the total amount of the black ink composition.

[0072] 1.1.9. Physical properties of black ink composition • Pizza The pH of the black ink composition is preferably 6.0 to 10.0 at 25°C. When the pH is within this range, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, it is possible to suitably obtain an ink set that can simultaneously reproduce superior black and light black while producing printed materials with superior granularity and fastness.

[0073] ·viscosity The viscosity of the black ink composition is preferably 1.5 mPa·s to 15 mPa·s at 20°C. When the viscosity is within this range, a black ink composition with superior blackness, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the black ink composition together with the light black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black simultaneously, while the printed material has superior granularity and fastness. In this specification, viscosity is measured, for example, using a viscoelasticity tester MCR-300 (manufactured by Pysica). Specifically, it can be measured by adjusting the temperature of the object to be measured, such as the reaction liquid composition, to 20°C and reading the shear viscosity (mPa·s) at a shear rate of 200 (1 / s).

[0074] 1.1.10. Method for producing a black ink composition A black ink composition can be prepared by mixing the above components in any order and removing impurities and foreign matter by filtration or other methods as necessary. Methods for mixing the components include sequentially adding each component to a container equipped with a stirring device such as a mechanical stirrer or magnetic stirrer, and then stirring and mixing them. Filtration methods include centrifugal filtration and filter filtration.

[0075] 1.2. Light Black Ink Composition 1.2.1. The fourth dye The light black ink composition contains a fourth dye having an anthraquinone skeleton, not containing chromium or copper, and having a hue angle ∠h° of 230° to 280° for the printed material. By using the fourth dye in combination with the second dye and / or the second dye, a light black ink composition with excellent light black color, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the light black ink composition together with the black ink composition, it is possible to suitably obtain an ink set that can simultaneously reproduce excellent black and light black while the printed material has excellent granularity and fastness. The fourth dye may be used alone or in combination of two or more types.

[0076] The fourth dye has an anthraquinone skeleton in its structure. Having such a specific structure allows the fourth dye to aggregate suitably with the second and third dyes. Therefore, printed materials obtained using a light black ink composition containing such a dye can exhibit excellent colorfastness.

[0077] The fourth dye does not contain chromium or copper. Therefore, using this fourth dye offers higher safety and reduces the environmental impact.

[0078] The fourth dye has a hue angle ∠h° of 230° to 280° for the printed material. Therefore, the fourth dye can reproduce a pale black color. Furthermore, by using such a fourth dye together with the complementary color components, the second and / or third dyes, the printed material can reproduce a good pale black color with a small number of dyes. Moreover, because there are fewer dyes, the printed material can have excellent granularity.

[0079] The fourth dye is preferably one in which the hue angle ∠h° of the printed material is between 240° and 270°. When the hue angle ∠h° is within the above range, the printed material can reproduce a better light black color and have a superior granular texture.

[0080] Examples of the fourth dye include CIAcid Blue 112, CIAcid Blue 140, and CIViolet 48.

[0081] The fourth dye preferably includes one or more selected from the group consisting of CIAcid Blue 112, CIAcid Blue 140, and CIViolet 48, and more preferably includes CIAcid Blue 140. These dyes, with fewer dye types, together with the second and / or third dyes, can reproduce a better light black color in the printed material and enable it to have superior granularity. Furthermore, since these dyes aggregate more favorably with the second and / or third dyes, the printed material can obtain superior color fastness.

[0082] The content of the fourth dye is preferably 0.5% by mass or more and 20.0% by mass or less, more preferably 1.0% by mass or more and 15.0% by mass or less, and even more preferably 2.0% by mass or more and 10.0% by mass or less, relative to the total amount of the light black ink composition. By using a fourth dye with a content within the above range together with the second dye and / or the second dye, a light black ink composition with superior light black color, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the light black ink composition together with the black ink composition, it is possible to suitably obtain an ink set that can simultaneously reproduce superior black and light black while the printed material has superior granularity and fastness.

[0083] 1.2.2. Second Dye and Third Dye The light black ink composition contains one or more dyes selected from the group consisting of a second dye having a naphthalene skeleton, not containing chromium or copper, and having a hue angle ∠h° of 35° to 55° for the printed material, and a third dye having a pyrazole skeleton, not containing chromium or copper, and having a hue angle ∠h° of 345° to 359° for the printed material. By including the second dye and / or the third dye together with a fourth dye, a light black ink composition with excellent light black color, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the light black ink composition together with the black ink composition, it is possible to suitably obtain an ink set that can simultaneously reproduce excellent black and light black while the printed material has excellent granularity and fastness. The second dye may be used alone or in combination of two or more. The third dye may be used alone or in combination of two or more.

[0084] • Second dye The second dye has a naphthalene skeleton in its structure. Having such a specific structure allows the second dye to aggregate suitably with the fourth dye and, optionally, the third dye. Therefore, printed materials obtained using a light black ink composition containing such dyes can exhibit excellent colorfastness.

[0085] The second dye does not contain chromium or copper. Therefore, using the second dye results in higher safety and a reduced environmental impact.

[0086] The second dye has a hue angle ∠h° of 35° to 55° for the printed material. Therefore, the second dye can reproduce a relatively dark orange color. Furthermore, by using the second dye as a complementary color component of the fourth dye, together with the third dye as needed, the printed material can reproduce a good light black color with fewer dye types. Moreover, because fewer dye types are used, the printed material can have superior granularity.

[0087] The second dye preferably has a hue angle ∠h° of 40° or more and 50° or less in the printed material. By using the second dye, whose hue angle ∠h° is within the above range, as the complementary color component of the fourth dye, along with the third dye as needed, the printed material can reproduce a better light black color and have a superior granular texture.

[0088] A second dye is, for example, CIAcid Orange 94.

[0089] The second dye preferably contains CIAcid Orange 94. By using CIAcid Orange 94 together with the fourth dye and, if necessary, the third dye, the printed material can reproduce a better light black color with fewer dye types and have superior granularity. Furthermore, since CIAcid Orange 94 aggregates more favorably with the fourth dye and, if necessary, the third dye, the printed material can obtain superior color fastness.

[0090] The content of the second dye is preferably 0.5% to 20.0% by mass, more preferably 1.0% to 15.0% by mass, and even more preferably 2.0% to 10.0% by mass, relative to the total amount of the light black ink composition. By using the second dye, whose content is within the above range, as a complementary color component of the fourth dye, along with the third dye which may be included as needed, a black ink composition with superior light black color, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the light black ink composition together with the black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black colors simultaneously, while the printed material has superior granularity and fastness.

[0091] • Third dye The third dye has a pyrazole skeleton in its structure. Having such a specific structure allows the third dye to suitably aggregate with the fourth dye and, if necessary, the second dye. Therefore, printed materials obtained using a light black ink composition containing such dyes can exhibit excellent colorfastness.

[0092] The third dye does not contain chromium or copper. Therefore, using this third dye offers higher safety and reduces the environmental impact.

[0093] The third dye has a hue angle ∠h° of 345° to 359° for the printed material. Therefore, the third dye can reproduce a relatively dark yellow. Furthermore, by using the third dye as a complementary color component of the fourth dye, together with the second dye as needed, the printed material can reproduce a good pale black color with a small number of dyes. Moreover, because there are fewer dyes, the printed material can have excellent granularity.

[0094] The third dye preferably has a hue angle ∠h° of 348° to 355° in the printed material. By using the third dye, whose hue angle ∠h° is within the above range, as the complementary color component of the fourth dye, along with the second dye as needed, the printed material can reproduce a better light black color and have a superior granular texture.

[0095] A third dye is, for example, CIAcid Yellow 79.

[0096] The third dye preferably contains CIAcid Yellow 79. By using CIAcid Yellow 79 together with the fourth dye and, if necessary, the second dye, the printed material can reproduce a better light black color with fewer dye types and can have superior granularity. Furthermore, since CIAcid Yellow 79 aggregates more favorably with the fourth dye and, if necessary, the second dye, the printed material can obtain superior color fastness.

[0097] The content of the third dye is preferably 0.5% to 20.0% by mass, more preferably 1.0% to 15.0% by mass, and even more preferably 2.0% to 10.0% by mass, relative to the total amount of the light black ink composition. By using the third dye, whose content is within the above range, as a complementary color component of the fourth dye, along with the second dye which is included as needed, a light black ink composition with superior light black color, granularity, and fastness can be obtained. Therefore, in the inkjet ink method, by using the light black ink composition together with the black ink composition, it is possible to suitably obtain an ink set that can simultaneously reproduce superior black and light black while the printed material has superior granularity and fastness.

[0098] 1.2.3.Water The light black ink composition contains water. The water used can be the same as that used in the black ink composition described above.

[0099] The water content is preferably 30.0% by mass or more and 80.0% by mass or less relative to the total amount of the light black ink composition. When the water content is within this range, an increase in the viscosity of the light black ink composition can be suppressed.

[0100] 1.2.4. Water-soluble organic solvents The light black ink composition preferably contains a water-soluble organic solvent. Functions of the water-soluble organic solvent include, for example, mitigating the water absorption behavior of the recording medium, improving the wettability of the light black ink composition to the recording medium, and enhancing the moisture retention of the light black ink composition. The water-soluble organic solvent can be the same as that contained in the black ink composition described above. The water-soluble organic solvent can be used individually or in combination of two or more types.

[0101] Preferably, the water-soluble organic solvent contains one or more selected from the group consisting of glycerin and triethylene glycol monobutyl ether. By using the above water-soluble organic solvent, a light black ink composition can be obtained that has better storage stability and superior light black color, granularity, and fastness. Therefore, in the inkjet ink method, by using the light black ink composition together with the black ink composition, an ink set can be suitably obtained that reproduces both superior black and light black colors simultaneously, while the printed material has superior granularity and fastness.

[0102] The content of the water-soluble organic solvent is preferably 0.1% to 40% by mass, more preferably 5.0% to 30% by mass, and even more preferably 10% to 25% by mass, based on the total amount of the light black ink composition. When the content of the water-soluble organic solvent is within the above range, a light black ink composition can be obtained that has better storage stability and better black color, granularity, and fastness. Therefore, by using the light black ink composition together with the black ink composition in the inkjet ink method, an ink set can be suitably obtained that can reproduce both better black and light black simultaneously, while the printed material has better granularity and fastness.

[0103] 1.2.5. Surfactants The light black ink composition preferably contains a surfactant. The surfactant has the function of lowering the surface tension of the light black ink composition and adjusting its wettability with the recording medium. The surfactant can be the same as the surfactant included in the black ink composition described above. The surfactant may be used alone or in combination of two or more types.

[0104] The surfactant preferably includes an acetylene glycol-based surfactant. By using the above-mentioned surfactant, the surface tension of the light black ink composition can be further reduced, allowing for better adjustment of the wettability with the recording medium.

[0105] The surfactant content is preferably 0.01% to 10% by mass, and more preferably 0.05% to 5.0% by mass, relative to the total amount of the ink composition. When the surfactant content is within the above range, a light black ink composition can be obtained that has superior light black color, granularity, and fastness. Therefore, by using the light black ink composition together with the black ink composition in the inkjet ink method, an ink set can be suitably obtained that can reproduce both superior black and light black colors simultaneously, while the printed material has superior granularity and fastness.

[0106] 1.2.6. Amines The light black ink composition may contain amines. The amines may function as pH adjusters. The amines used may be those found in the black ink composition described above. The amines may be used individually or in combination of two or more.

[0107] The amine content is preferably 0.01% to 10% by mass, and more preferably 0.05% to 5.0% by mass, relative to the total amount of the light black ink composition. When the amine content is within the above range, a light black ink composition with superior light black color, granularity, and fastness can be obtained. Therefore, by using the light black ink composition together with the black ink composition in the inkjet ink method, an ink set can be suitably obtained that reproduces both superior black and light black colors simultaneously, while the printed material has superior granularity and fastness.

[0108] 1.2.7.Ureas The light black ink composition may contain ureas. Ureas tend to function as humectants and dyeing aids that improve the dye adhesion of the dye in the light black ink composition. The ureas included in the black ink composition described above may be used as examples. Ureas may be used individually or in combination of two or more types.

[0109] The urea content is preferably 0.1% by mass or more and 10% by mass or less relative to the total amount of the light black ink composition. When the urea content is within the above range, a light black ink composition with superior light black color, granularity, and fastness can be obtained. Therefore, by using the light black ink composition together with the black ink composition in the inkjet ink method, an ink set can be suitably obtained that reproduces both superior black and light black colors simultaneously, while the printed material has superior granularity and fastness.

[0110] 1.2.8. Other Ingredients The light black ink composition may also contain various additives that are commonly used in ink compositions, other than the components mentioned above, such as sugars, preservatives, fungicides, solubilizers, viscosity modifiers, pH adjusters, antioxidants, ultraviolet absorbers, oxygen absorbers, rust inhibitors, corrosion inhibitors, and chelating agents. Additives may be used individually or in combination of two or more.

[0111] The additive content is preferably 0.01% by mass or more and 10.0% by mass or less in total, relative to the total amount of the light black ink composition.

[0112] 1.2.9. Physical properties of light black ink compositions • Pizza The pH of the light black ink composition is preferably 6.0 to 10.0 at 25°C. When the pH is within this range, a light black ink composition with superior light black color, granularity, and fastness can be obtained. Therefore, by using the light black ink composition together with the black ink composition in the inkjet ink method, it is possible to suitably obtain an ink set that can simultaneously reproduce superior black and light black colors while producing printed materials with superior granularity and fastness.

[0113] ·viscosity The viscosity of the light black ink composition is preferably 1.5 mPa·s to 15 mPa·s at 20°C. When the viscosity is within this range, a light black ink composition with superior light black color, granularity, and fastness can be obtained. Therefore, by using the light black ink composition together with the black ink composition in the inkjet ink method, it is possible to suitably obtain an ink set that can reproduce both superior black and light black colors simultaneously, while the printed material has superior granularity and fastness.

[0114] 1.2.10. Method for producing a light black ink composition A light black ink composition can be prepared by mixing the above components in any order and removing impurities and foreign matter by filtration or other means as necessary. For the mixing method and filtration method of each component, refer to the mixing method and filtration method for the black ink composition described above.

[0115] 2. Inkjet recording method The inkjet recording method of this embodiment is performed using the inkjet ink set according to this embodiment. Specifically, the inkjet recording method includes the step of ejecting the black ink composition and the light black ink composition from the ink set from the inkjet head and adhering them to the recording medium. Figure 1 shows an example of the inkjet recording method of this embodiment. This inkjet recording method includes an ink adhesion step and a heating step in that order. Next, the recording medium, the inkjet recording apparatus that can be used in the recording method, and the process will be described.

[0116] 2.1 Recording media Examples of recording media include absorbent recording media and fabrics. Of these, fabrics are preferred.

[0117] Examples of absorbent recording media include those containing fabric, such as those with high permeability to black ink compositions and light black ink compositions, as well as plain paper such as electrophotographic paper and inkjet paper, and art paper, coated paper, and cast paper used in general offset printing, which have relatively low permeability to ink compositions.

[0118] Examples of raw materials for woven fabrics include blends of silk, cotton, wool, nylon, polyester, polyamide, and polyurethane; biodegradable fibers such as polylactic acid; and natural and synthetic fibers such as rayon. The woven fabric may consist of one type of fiber or a blend of two or more types of fibers. The woven fabric may be made from the fibers listed above in any form, such as woven, knitted, or nonwoven fabric.

[0119] The raw yarn for the fabric is preferably nylon, wool, or silk, and more preferably nylon and silk. According to Inkset, stable and excellent black and light black colors can be produced even for fabrics other than nylon and silk.

[0120] When the recording medium is a fabric, the inkjet recording method comprises a transport step of transporting the recording medium including the fabric, and a recording step of recording a black ink composition and a light black ink composition onto the recording medium. Alternatively, the recording method of this embodiment may be a printing method in which the recording medium includes a fabric. In the printing method, in addition to the recording step, a heating step and a washing step may further be included.

[0121] 2.2. Inkjet Recording Devices Inkjet recording devices can be either serial or line type. These types of inkjet recording devices are equipped with an inkjet head, and by changing the relative positional relationship between the recording medium and the inkjet head, droplets of black ink composition and light black ink composition are ejected from the nozzle holes of the inkjet head at a predetermined timing and in a predetermined volume (mass), thereby depositing the black ink composition and light black ink composition onto the recording medium and forming a predetermined image.

[0122] The inkjet recording device may optionally employ known components such as a drying unit, a roll unit, and a winding device. The inkjet recording device may also have, for example, a transport means for transporting a recording medium, an image layer forming means for recording an image using an ink composition, a drying means, and an overall drying means for heating and blowing air onto the recording surface.

[0123] The conveying means is composed of, for example, rollers. In this case, it may have multiple rollers. Another method is to convey the recording medium by adhering it to and being attracted to a rubber belt or the like. The position and number of conveying means can be arbitrarily adopted as long as the recording medium can be conveyed. The conveying means may include a roll mechanism, trays, and various platens.

[0124] The image layer forming means records an image layer by ejecting a black ink composition and a light black ink composition onto the recording surface of the recording medium. The image layer forming means is equipped with an inkjet head with nozzles, and a nozzle row is assigned to each predetermined black ink composition, light black ink composition, and other ink compositions.

[0125] Drying means can be used to heat, dry, and / or remove volatile components from the recording medium of the image layer formed on the recording surface. The drying means may be installed at any position considering the timing of the adhesion process and the transport path of the recording medium. Examples of image layer drying means include methods of applying heat to the recording medium by platen heating, methods of blowing air onto the image on the recording medium, and methods combining these. Specifically, examples of means used in these methods include forced air heating, radiant heating, conductive heating, high-frequency drying, and microwave drying.

[0126] 2.3. Each step of the recording method The process of attaching the black ink composition and the light black ink composition to the recording medium can be carried out using an inkjet recording device. Specifically, the black ink composition and the light black ink composition can be attached to the recording medium by filling the inkjet head so that they can be ejected from predetermined nozzles, and then ejecting them onto the recording medium at a predetermined timing.

[0127] The recording method may include a step of heating the recording medium as appropriate. For example, when using an inkjet recording device, the above-mentioned drying means can be used for the heating step. The method is not limited to an inkjet recording device; other drying means may be used as appropriate. Including a heating step in the recording method suppresses image blurring and allows for more efficient image fixing.

[0128] The recording method may include other steps. Such steps include, for example, applying another ink composition and a cleaning step.

[0129] In the recording method, since the ink set according to this embodiment is used, the printed material has excellent granularity and fastness, and can record an image that simultaneously reproduces excellent black and light black colors.

[0130] 2.4. Printing Method The printing method may be an inkjet printing method in which a black ink composition and a light black ink composition are filled into an inkjet device. Examples of inkjet devices include drop-on-demand inkjet devices. Drop-on-demand inkjet devices include devices that employ an inkjet printing method using a piezoelectric element disposed on the head, and devices that employ an inkjet printing method using thermal energy from a heater or the like of a heating resistance element disposed on the head.

[0131] 2.4.1. Conveying Process The transport process is the process of transporting the recording medium, including the fabric. Examples of transport methods for the recording medium include known transport methods, such as those used in inkjet printing.

[0132] 2.4.2. Recording Process The recording process involves recording a black ink composition and a light black ink composition onto a recording medium. When using an inkjet method, the black ink composition and the light black ink composition are ejected by the inkjet method toward the surface of the fabric (image-forming area), which is at least a part of the recording medium, and adhered to the recording medium to form an image. The ejection conditions can be appropriately determined based on the physical properties of the ejected black ink composition and light black ink composition.

[0133] 2.4.3.Heating process The printing method may further include a heating step after the recording step, in which the recording medium to which the black ink composition and the light black ink composition have been attached is heated. By including a heating step, the colorants can be dyed more effectively onto the fibers constituting the fabric. Examples of heating methods include high-temperature steaming, high-pressure steaming, and thermosol.

[0134] In the heating process, the black ink composition surface and the light black ink composition surface on the recording medium may or may not be subjected to pressure treatment. Examples of heating methods that do not involve pressurizing the black ink composition surface and the light black ink composition surface on the recording medium include oven drying, i.e., non-pressurizing methods such as conveyor ovens and batch ovens. Having such a heating process further improves the productivity of the recorded material. Examples of heating methods that involve pressurizing the black ink composition surface and the light black ink composition surface on the recording medium include heat pressing and wet-on-drying. In this embodiment, pressurization refers to applying pressure to the recording medium by bringing a solid into contact with it.

[0135] The temperature during heat treatment is preferably between 80°C and 150°C, and more preferably between 90°C and 110°C. A temperature within this range tends to allow for better dyeing of the colorant to the fibers constituting the fabric.

[0136] 2.4.4. Washing Process The printing method may further include a washing step after the heating step, in which the recording medium to which the black ink composition and the light black ink composition have adhered is washed. The washing step can effectively remove acidic dyes that have not adhered to the fibers. The washing step can be carried out, for example, using water.

[0137] In this way, a recording material such as a printed object can be obtained in which an image derived from a black ink composition and a light black ink composition is formed on a recording medium including a fabric.

[0138] 2.4.5. Process for attaching the treatment liquid composition The fabric used for printing may be the fabric itself, or it may be the fabric that has been pre-treated with the processing solution composition. That is, the printing method may include a step of applying the processing solution composition to the fabric that is to be used as the recording medium. Pre-treating the fabric reduces image blurring and allows for clear and efficient dyeing. The pre-treatment of the fabric with the processing solution composition can be any conventionally known method.

[0139] The processing solution composition typically includes a thickening agent, a surfactant, a pH adjuster, a hydrotropic agent, and water. Depending on the application, silica may also be included.

[0140] Examples of adhesives include natural gums such as guar gum and locust bean gum; starches; sodium alginate and seaweed such as funori; plant peels such as pectin; cellulose derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose, and etherified carboxymethylcellulose; modified starches such as roasted starch, alpha starch, carboxymethyl starch, carboxyethyl starch, and hydroxyethyl starch; modified natural gums such as syrup gum and roasted bean gum; algin derivatives; synthetic adhesives such as polyvinyl alcohol and polyacrylic acid esters; and emulsions.

[0141] As the surfactant, the surfactant contained in the black ink composition described above may be used. Alternatively, a nonionic surfactant such as polyoxyethylene diisopropyl ether may be used.

[0142] Examples of pH adjusting agents include sodium m-benzenesulfonate, ammonium ammonium acid salts, ammonium sulfate, sodium carbonate, and ammonium tartrate.

[0143] Examples of hydrotropic agents include urea, dimethylurea, thiourea, monomethylthiourea, and alkylureas of dimethylthiourea.

[0144] The water may refer to the water contained in the black ink composition described above.

[0145] The processing liquid composition can be prepared by mixing each component in any order and, if necessary, removing impurities and foreign matter by filtration or other means. Methods for mixing the components include sequentially adding each component to a container equipped with a stirring device such as a mechanical stirrer or magnetic stirrer, and then stirring and mixing them. Filtration methods include centrifugal filtration and filter filtration.

[0146] Methods for applying the treatment liquid composition to a fabric include, for example, an immersion coating method in which the fabric is immersed in the treatment liquid composition; a roller coating method in which the treatment liquid composition is applied using a mangle roller and a roll coater; a spray coating method in which the treatment liquid composition is sprayed using a spray device; and an inkjet coating method in which the treatment liquid composition is sprayed using an inkjet method. These coating methods may be used individually to apply the treatment liquid composition to the fabric, or two or more methods may be combined to apply the treatment liquid composition to the fabric.

[0147] After applying the treatment solution composition to the fabric, it is preferable to heat and dry the fabric to which the treatment solution composition has been applied, if necessary. The drying method may refer to the heating step described above. [Examples]

[0148] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Hereinafter, unless otherwise specified, "parts" refers to parts by mass.

[0149] 1. Measurement of the hue angle ∠h° of printed materials with the first to fourth dyes and other dyes. The hue angles ∠h° of the printed materials for the first to fourth dyes and the other dyes were measured as follows: Specifically, an inkjet printer (Seiko Epson Corporation, product name "PX-G930") was filled with the first to fourth dyes, as well as other dyes, to form an image on transfer paper (Sappi Corporation, product name "Transjet Sportsline"). Specifically, at a resolution of 720 dpi horizontally and 720 dpi vertically, with a 100% duty cycle ink output, the ink density was 12 mg / inch. 2 A fill pattern that could be recorded under these conditions was created and used.

[0150] Next, the recording surface of the transfer paper on which the image is formed and a white polyester fabric (manufactured by Toray Industries, Inc., product name "SS-755 K-1", whiteness L) are placed. *With the values ​​89) facing each other, a heat press machine (Taiyo Seiki Co., Ltd., product name "TP-608M") is used to press at a temperature of 200°C for 60 seconds at a rate of 4.2 N / cm². 3 It was heat-transferred using pressure.

[0151] The obtained evaluation samples were determined using a spectrophotometer (product name "FD-7", manufactured by Konica Minolta, Inc., measurement conditions: light source D65, filter D65, φ2 degrees). * value, b * The hue angle ∠h° was calculated from the values.

[0152] Next, the hue angle ∠h° measured for each of the first to fourth dyes and the other dyes is shown along with the structure of the dye.

[0153] [First dye] • Acid Blue 113…CIAcid Blue 113 (commercially available product) Acid Blue 113 had a naphthalene skeleton and did not contain chromium or copper. Furthermore, the hue angle ∠h° of the printed material was between 270° and 290°.

[0154] [Second dye] • Acid Orange 94…CI Acid Orange 94 (commercial product) Acid Orange 94 had a naphthalene skeleton and did not contain chromium or copper. Furthermore, the hue angle ∠h° of the printed material was between 35° and 55°.

[0155] [The third dye] • Acid Yellow 79…CI Acid Yellow 79 (commercially available product) Acid Yellow 79 had a pyrazole skeleton and did not contain chromium or copper. Furthermore, the hue angle ∠h° of the printed material was between 345° and 359°.

[0156] [The fourth dye] • Acid Blue 112…CIAcid Blue 112 (commercially available product) Acid Blue 112 had an anthraquinone skeleton and did not contain chromium or copper. Furthermore, the hue angle ∠h° of the printed material was between 230° and 280°. • Acid Blue 140…CIAcid Blue 140 (commercially available product) Acid Blue 140 had an anthraquinone skeleton and did not contain chromium or copper. Furthermore, the hue angle ∠h° of the printed material was between 230° and 280°. • Acid Violet 48…CI Acid Violet 48 (commercially available product) Acid Violet 48 had an anthraquinone skeleton and did not contain chromium or copper. Furthermore, the hue angle ∠h° of the printed material was between 230° and 280°.

[0157] [Other dyes] • Direct Blue 87…CIDirect Blue 87 (commercial product) • Acid Red 138…CIAcid Red 138 (commercial product)

[0158] 2. Preparation of black inkjet ink composition and light black inkjet ink composition (Preparation Examples 1-8) Each component was placed in a mixing tank to obtain the composition shown in Table 1, mixed and stirred with a magnetic stirrer for 2 hours, and then filtered through a membrane filter with a pore size of 5 μm to obtain the black inkjet ink compositions according to Preparation Examples 1 to 4 and the light black inkjet ink compositions according to Preparation Examples 5 to 8, respectively. Note that the values ​​in Table 1 represent mass percentages. The mass percentages for dyes 1 through 4 and other dyes are shown as solid content. Deionized water was used and added to each ink composition so that its mass reached 100% by mass.

[0159] The components shown in Table 1 are as follows:

[0160] [The first to fourth dyes, and other dyes] The above dyes were used as the first to fourth dyes, and as other dyes, respectively.

[0161] [Water-soluble organic solvents] Glycerin Triethylene glycol monobutyl ether

[0162] [Surfactants] • PD002W…OLFIN (registered trademark) PD002W (product name, Nisshin Chemical Industry Co., Ltd.)

[0163] 3. Preparation of printed materials (Examples 1-2 and Comparative Examples 1-7) Using the black inkjet ink compositions from Preparation Examples 1-4 and the light black inkjet ink compositions from Preparation Examples 5-8, the black ink composition and / or light black ink composition were attached to a fabric as a recording medium, as shown in Table 2. Specifically, a fabric to which the black ink composition and / or light black ink composition were attached was obtained as follows.

[0164] First, a nylon cloth (nylon 6 taffeta, manufactured by Irozome Co., Ltd.) was prepared as the fabric, and the following pretreatment solution was applied to it. The cloth was then squeezed with a mangle at a pick-up rate of 20% and dried to obtain a fabric to which the pretreatment solution had adhered. Sodium alginate: 1.0% by mass Guar gum: 1.0% by mass Ammonium sulfate: 4.0% by mass Urea: 10.0% by mass Water: 84.0% by mass

[0165] The black inkjet ink compositions from Preparation Examples 1-4 and the light black inkjet ink compositions from Preparation Examples 5-8 were each filled into cartridges of an inkjet printer, the Monna Lisa-32000 (product name, manufactured by Seiko Epson Corporation). Subsequently, the fabric to which the above pretreatment solution had adhered was inked at a resolution of 720 dpi x 720 dpi with an ink density of 23 mg / inch. 2Under these conditions, black areas, where the black ink composition was applied, and light black areas, where the light black ink composition was applied, were formed as shown in Table 2. Specifically, in Example 1, black areas, where the black ink composition of Preparation Example 1 was applied, and light black areas, where the light black ink composition of Preparation Example 5 was applied, were formed on separate parts of the fabric to which the above pretreatment liquid was applied. In Comparative Example 1, images were formed on separate parts of the fabric to which the above pretreatment liquid was applied, using the black ink composition of Preparation Example 1 as both the black areas and the light black areas.

[0166] Each of the fabrics on which the image was formed was steamed at 102°C for 30 minutes, then washed at 55°C for 10 minutes with an aqueous solution containing 0.2% by mass of Laccol STA (manufactured by Meisei Chemical Co., Ltd., surfactant), and dried to obtain the printed material.

[0167] 4. Evaluation Method 4.1. Color development The color development of each printed material obtained as described above was evaluated. Specifically, the optical density (hereinafter also referred to as "OD value") of the black and light black areas of each obtained printed material was measured using the colorimeter "Xrite i1" (product name, manufactured by Xrite), and the color development was evaluated according to the following criteria. The results are shown in Table 2. 〔standard〕 (Black part) AA: The OD value was 1.5 or higher. A: The OD value was between 1.4 and 1.5. B: The OD value was between 1.3 and 1.4. The C:OD value was between 1.2 and 1.3. The D:OD value was less than 1.2. (Light black area) AA: The OD value was less than 0.3. A: The OD value was between 0.3 and less than 0.5. B: The OD value was between 0.5 and less than 0.7. The C:OD value was between 0.7 and less than 0.9. The D:OD value was 0.9 or higher.

[0168] 4.2.Graininess The granularity of each printed material obtained as described above was evaluated. Specifically, the black and light black areas of each printed material were observed visually from a distance of 30 cm from the printed surface, and the granularity was evaluated according to the following criteria. The results are shown in Table 2. 〔standard〕 (Black part) AA: No graininess is perceptible at all when observed visually from a distance of 30 cm from the printed surface. A: When observed visually from a distance of 30 cm from the printed surface, a slight graininess can be perceived. B: The granular texture can be perceived when observed visually from a distance of 30 cm from the printed surface. C: When observed visually from a distance of more than 30 cm from the printed surface, some granularity can be perceived. D: The granular texture can be recognized even when observed visually from a distance of more than 30 cm from the printed surface. (Light black area) AA: No graininess is perceptible at all when observed visually from a distance of 30 cm from the printed surface. A: When observed visually from a distance of 30 cm from the printed surface, a slight graininess can be perceived. B: The granular texture can be perceived when observed visually from a distance of 30 cm from the printed surface. C: When observed visually from a distance of more than 30 cm from the printed surface, some granularity can be perceived. D: The granular texture can be recognized even when observed visually from a distance of more than 30 cm from the printed surface.

[0169] 4.3. Robustness The fastness of each printed material obtained as described above was evaluated. Specifically, the wet rub fastness of the black and light black areas of each printed material was evaluated according to the following criteria in accordance with ISO 105 X12. The tests were performed using the clock meter method. The results are shown in Table 2. 〔standard〕 (Black part) AA: Wet friction fastness is grade 4 or higher. A: Wet friction fastness is grade 3-4 (intermediate grade). B: Wet friction fastness is grade 2-3 (intermediate grade). C: Wet friction fastness is grade 1-2 (intermediate grade). D: Wet friction fastness is less than Grade 1. (Light black area) AA: Wet friction fastness is grade 4 or higher. A: Wet friction fastness is grade 3-4 (intermediate grade). B: Wet friction fastness is grade 2-3 (intermediate grade). C: Wet friction fastness is grade 1-2 (intermediate grade). D: Wet friction fastness is less than Grade 1.

[0170] As shown in Table 2, it was found that the ink set of this embodiment can reproduce both excellent black and light black colors simultaneously, while the printed material exhibits excellent granularity and fastness.

[0171] Furthermore, a comparison between Examples 1 and 2 revealed that by using CIAcid Blue 140 as the fourth dye in conjunction with the second and third dyes, the printed material exhibits excellent colorfastness, produces a superior black color, has better granularity, and can reproduce a superior light black color.

[0172] As shown in Comparative Example 1, when a black ink composition is used as the light black ink composition in the ink set, the printed material has poor granularity and fastness, and it was found that a good light black color could not be reproduced.

[0173] As shown in Comparative Example 2, it was found that when a light black ink composition was used as the black ink composition in the ink set, the printed material had poor granularity and could not reproduce a good black color.

[0174] As shown in Comparative Examples 3 and 4, when a black ink composition containing the fourth dye but not the first dye was used in the ink set, the printed material tended to have poor granularity and it was found that a good black color could not be reproduced.

[0175] As shown in Comparative Example 5, when a black ink composition that does not contain the second and third dyes is used in the ink set, it was found that the printed material has poor color fastness and cannot reproduce a good black color.

[0176] As shown in Comparative Example 6, it was found that when a light black ink composition without the second dye was used in the ink set, the printed material had poor granularity.

[0177] As shown in Comparative Example 8, when a black ink composition with relatively small amounts of the first to third dyes was used as the light black ink composition in the ink set, the printed material exhibited a light black color, and although excellent granularity was obtained due to the low amount of dye, excellent color fastness was not achieved.

Claims

1. An inkjet ink set comprising a black inkjet ink composition and a light black inkjet ink composition, The aforementioned black ink composition A first dye having a naphthalene skeleton, not containing chromium or copper, and having a hue angle ∠h° of 270° or more and 290° or less of the printed material, One or more dyes selected from the group consisting of a second dye having a naphthalene skeleton, not containing chromium or copper, and having a hue angle ∠h° of 35° or more and 55° or less for the printed material, and a third dye having a pyrazole skeleton, not containing chromium or copper, and having a hue angle ∠h° of 345° or more and 359° or less for the printed material, Water and, The aforementioned light black ink composition A fourth dye having an anthraquinone skeleton, not containing chromium or copper, and having a hue angle ∠h° of 230° or more and 280° or less for the printed material, One or more selected from the group consisting of the second dye and the third dye, Water and, Ink set.

2. The ink set according to claim 1, wherein the first dye comprises C.I. Acid Blue 113.

3. The ink set according to claim 1, wherein the fourth dye comprises one or more selected from the group consisting of C.I. Acid Blue 112, C.I. Acid Blue 140, and C.I. Acid Violet 48.

4. The second dye in the black ink composition comprises C.I. Acid Orange 94. The second dye in the light black ink composition contains C.I. Acid Orange 94. The ink set according to claim 1.

5. The third dye in the black ink composition comprises C.I. Acid Yellow 79. The third dye in the light black ink composition comprises C.I. Acid Yellow 79. The ink set according to claim 1.

6. In the aforementioned black ink composition, The content of the first dye is 0.5% by mass or more and 20.0% by mass or less, relative to the total amount of the black ink composition. The content of the second dye is 0.5% by mass or more and 20.0% by mass or less, relative to the total amount of the black ink composition. The content of the third dye is 0.5% by mass or more and 20.0% by mass or less, relative to the total amount of the black ink composition. The ink set according to claim 1.

7. In the aforementioned light black ink composition, The content of the fourth dye is 0.5% by mass or more and 20.0% by mass or less, relative to the total amount of the light black ink composition. The content of the second dye is 0.5% by mass or more and 20.0% by mass or less, relative to the total amount of the light black ink composition. The content of the third dye is 0.5% by mass or more and 20.0% by mass or less, relative to the total amount of the light black ink composition. The ink set according to claim 1.

8. The pH of the black ink composition is 6.0 or higher and 10.0 or lower. The pH of the aforementioned light black ink composition is 6.0 or higher and 10.0 or lower. The ink set according to claim 1.

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