Inkjet ink composition

Abstract

To provide an ink composition that has excellent color development and light resistance, can avoid the clogging of a nozzle even when the head is dried after long-term storage, and can improve clogging recoverability.SOLUTION: A composition includes a coloring material of the following formula (1), a water-soluble organic solvent, and water.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an inkjet ink composition.

Background Art

[0002] The inkjet method has been attempted not only for recording images on a recording medium but also for printing on fabrics, and various ink compositions for inkjet printing have been studied. For example, Patent Document 1 describes an inkjet ink composition for printing having color development properties and fastness by specifying the types of rust inhibitors and pH adjusters.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the inkjet ink composition for printing of Patent Document 1, when it contains C.I. Reactive Black 8 as a coloring material, there are problems such as poor color development properties and light resistance, and nozzle clogging due to head drying after long-term storage.

Means for Solving the Problems

[0005] The present invention includes a coloring material, a water-soluble organic solvent, and water, and the coloring material includes a compound (A) in which Me is Cr (chromium) in the structure represented by the following formula (1) and a compound (B) in which Me is Co (cobalt) in the structure represented by the following formula (1), and the mass ratio of the compound (B) to the compound (A) (the compound (B) / the compound (A)) is more than 0 and 0.06 or less, which is an inkjet ink composition.

[0006]

Chemical Formula

[0007] [Figure 1] This flowchart shows an example of the recording method according to this embodiment. [Modes for carrying out the invention]

[0008] 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.

[0009] 1. Inkjet ink composition The inkjet ink composition of this embodiment (hereinafter also referred to as "ink composition") comprises a colorant, a water-soluble organic solvent, and water, wherein the colorant comprises compound (A) in which Me is Cr (chromium) in the structure represented by the following formula (1), and compound (B) in which Me is Co (cobalt) in the structure represented by the following formula (1), and the mass ratio of compound (B) to compound (A) (compound (B) / compound (A)) is greater than 0 and less than or equal to 0.06.

[0010] [ka]

[0011] According to this embodiment, an ink composition can be obtained that has excellent color development and lightfastness, can suppress nozzle clogging even if the print head dries out after long-term storage, and can improve clogging recovery.

[0012] Although the reason why this embodiment yields such excellent results is not entirely clear, the inventors of the present invention surmise the following. Inkjet ink compositions containing a colorant comprising compound (A) and compound (B), such as CIReactive Black 8, have poor color development and lightfastness, and nozzle clogging occurs after long-term storage due to drying of the print head. Compound (A) exhibits excellent color development and high solubility in solvents such as water, resulting in superior clogging recovery. However, due to its superior solubility, it tends to have poor lightfastness. Compound (B), on the other hand, exhibits excellent lightfastness, but has very poor solvent solubility and tends to have poor color development. However, the colorant according to this embodiment contains compound (A) and compound (B), and their mass ratio is within a specific range. Therefore, it is presumed that a synergistic effect between compound (A) and compound (B) can be achieved, resulting in an ink composition with excellent color development, lightfastness, and clogging recovery properties. However, the reasons are not limited to this.

[0013] Next, we will explain each component contained in the ink composition.

[0014] 1.1. Colorants The ink composition contains, as a colorant, compound (A) in the structure represented by formula (1) above, where Me is Cr, and compound (B) in the structure represented by formula (1) above, where Me is Co. In the colorant, the mass ratio of compound (B) to compound (A) (compound (B) / compound (A)) is greater than 0 and less than or equal to 0.06. Such a colorant is a reactive dye. The colorant may be used alone or in combination of two or more types.

[0015] Since an ink composition with superior color development, lightfastness, and clogging recovery properties can be obtained, it is preferable that the mass ratio of compound (B) to compound (A) (compound (B) / compound (A)) is 0.005 or more and 0.06 or less.

[0016] The colorant further contains a compound (C) having a structure represented by the following formula (2), and the mass ratio of the compound (A) and the compound (B) to the compound (C) ((compound (A) + compound (B)) / compound (C)) is preferably 4 or more and 20 or less. The compound (C) may be contained alone or in combination of two or more.

[0017]

Chemical formula

[0018] In formula (2), Me is Cr or Co, and X1 and X2 are each independently a chlorine atom or an amino group. However, X1 and X2 are not chlorine atoms at the same time.

[0019] When the colorant contains the compound (C) at a specific mass ratio ((compound (A) + compound (B)) / compound (C)) together with the compound (A) and the compound (B), it has better light resistance and clogging recovery properties, and the color development property for a fabric containing at least one of cotton and silk as a raw yarn (hereinafter simply referred to as "fabric of cotton and silk") tends to be even more excellent. In particular, the color development property for silk tends to be even more excellent. Although the reason for this is not clear, the present inventors presume as follows. That is, good color development is obtained when X1 and X2 simultaneously have chlorine atoms in the structure represented by formula (2). On the other hand, in the compound (C), X1 and X2 are not chlorine atoms at the same time, and one of X1 and X2 is a chlorine atom and the other is an amino group, or both are amino groups. Therefore, although good color development property tends not to be obtained, it has excellent adhesion to fabrics of cotton and silk. And the compound (C) has good affinity with the compound (A) and the compound (B). Therefore, by using the compound (C) together with the compound (A) and the compound (B) at a specific mass ratio for fabrics of cotton and silk, it becomes possible to further exhibit the synergistic effect of the compound (A) and the compound (B). As a result, it is presumed that an ink composition having particularly excellent color development property can be obtained. However, the reason is not limited to this.

[0020] Furthermore, since it has superior lightfastness and clogging recovery properties, and tends to have even better color development on cotton and silk fabrics, it is preferable that Me in formula (2) is Cr.

[0021] Furthermore, it is preferable that X1 and X2 in formula (2) are both amino groups, as they have superior lightfastness and clogging recovery properties, and tend to have even better color development on cotton and silk fabrics.

[0022] In this embodiment, the colorant can be obtained by purifying commercially available CIReactive Black 8 using a known method. Examples of such purification methods include activated carbon filtration, microfiltration, and ultrafiltration. Furthermore, to ensure more reliable purification, it is preferable to perform pretreatment before purification, such as dissolving CIReactive Black 8 in water and then adjusting the pH or ion-exchanging heavy metals. The mass ratios of compound (A), compound (B), and compound (C) can be calculated, for example, using a liquid chromatograph-mass spectrometer (LC-MS), a nuclear magnetic resonance spectrometer (NMR), and a Fourier transform infrared spectrophotometer (FT-IR). The mass ratio of compound (B) to compound (A) can be calculated, for example, by elemental and quantitative analysis using an inductively coupled plasma emission spectrometer (ICP-OES) and an X-ray fluorescence spectrometer (XRF). The mass ratios of compound (A) and compound (B) to compound (C) can be calculated using a liquid chromatograph-mass spectrometer (LC-MS), a nuclear magnetic resonance spectrometer (NMR), and a Fourier transform infrared spectrophotometer (FT-IR).

[0023] Since an ink composition with superior color development and lightfastness, and even better clogging recovery properties can be obtained, the colorant content is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 7% by mass or less, and even more preferably 5% by mass or less, based on the total amount of the ink composition. The lower limit of the colorant content is not particularly limited as long as the effects of this embodiment are achieved, but for example, it may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total amount of the ink composition.

[0024] 1.2. Water-soluble organic solvents The ink composition contains a water-soluble organic solvent. Examples of such water-soluble organic solvents include glycerin; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; glycol monoethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, and triethylene glycol monobutyl ether; and alcohols such as methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol. Water-soluble organic solvents may be used individually or in combination of two or more types.

[0025] Among these, glycols can function as humectants. Glycol monoethers, on the other hand, can function as penetrating agents.

[0026] From the viewpoint of achieving the effects of this embodiment more effectively and reliably, the content of the water-soluble organic solvent is preferably 5% by mass or more and 30% by mass or less in total with respect to the total amount of the ink composition.

[0027] 1.3.Water The ink composition contains water. Examples of suitable water include pure water such as ion-exchanged 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 preferable because it can suppress the growth of mold and bacteria when the treatment solution composition is stored for a long period of time.

[0028] The water content is preferably 30% by mass or more and 80% by mass or less of the total amount of the ink composition. By keeping the water content within the above range, an increase in the viscosity of the ink composition can be suppressed.

[0029] 1.4. Other reactive dyes The ink composition may also contain other reactive dyes. Examples of such reactive dyes include CIReactive Orange 1, 2, 4, 5, 7, 11, 12, 13, 15, 16, 20, 30, 35, 56, 64, 67, 69, 70, 72, 74, 82, 84, 86, 87, 91, 92, 93, 95, 99, 107; CIReactive Red 2, 3, 3:1, 4, 5, 7, 8, 11, 12, 13, 15, 16, 21, 22, 23, 24, 24:1, 25, 26, 28, 29, 31, 32, 33, 35, 39, 40, 41, 43, 45, 46, 49, 55, 56, 58, 59, 65, 66, 78, 83, 106, 111, 112, 113, 11 4, 116, 120, 123, 124, 128, 130, 136, 141, 147, 158, 159, 171, 174, 176, 180, 183, 18 4, 187, 190, 193, 194, 195, 198, 218, 220, 222, 223, 226, 228, 235, 245;CIReactive Yellow 2, 3, 6, 7, 12, 15, 17, 18, 22, 23, 24, 25, 27, 37, 39, 42, 57, 69, 76, 81, 84, 85, 86, 87, 92, 95, 102, 10 5, 111, 125, 135, 136, 137, 142, 143, 145, 151, 160, 161, 165, 167, 168, 175, 176, 181;CIReactive Blue 2, 3, 4, 5, 7, 13, 14, 15, 19, 21, 25, 26, 27, 28, 29, 38, 39, 40, 41, 46, 49, 50, 52, 63, 69, 71, 72, 77, 79, 89, 104, 109, 112, 113, 114, 116, 119, 120, 122, 13 7, 140, 143, 147, 160, 161, 162, 163, 168, 171, 176, 182, 184, 191, 194, 195, 198, 203, 204, 207, 209, 211, 214, 220, 221, 222, 231, 235, 236;CIReactive Black 1, 2, 3, 5, 8, 10, 12, 13, 14, 31, 34, 39;CIReactive Violet 1, 2, 4, 5, 6, 22, 23, 33, 36, 38;CIReactive Green 5, 8, 12, 15, 19, 21;CIReactive Browns 1, 2, 7, 8, 9, 10, 11, 14, 17, 18, 19, 21, 23, 31, 37, 43, and 46 are examples. Other reactive dyes may be used individually or in combination of two or more.

[0030] The ink composition preferably contains one or more selected from CIReactive Orange 13, CIReactive Orange 99, CIReactive Yellow 95, CIReactive Red 245, CIReactive Brown 11, CIReactive Blue 49, CIReactive Orange 12, and CIReactive Red 24:1, and more preferably contains CIReactive Orange 12 and / or CIReactive Red 24:1, as it has superior color development, lightfastness, and clogging recovery, and in particular can achieve a good gray color.

[0031] Furthermore, because it has superior color development, lightfastness, and clogging recovery properties, and in particular can achieve a better gray color, the content of other reactive dyes is preferably 0.01% to 20% by mass, and more preferably 0.05% to 10% by mass, relative to the total amount of the ink composition. It is also preferable that it be 0.5% to 10% by mass.

[0032] 1.5. Surfactants The ink composition may contain a surfactant. Surfactants have the function of lowering the surface tension of the ink composition and adjusting its wettability with the recording medium. Examples of surfactants include acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants.

[0033] 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.).

[0034] 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.).

[0035] Examples of fluorinated surfactants include fluorine-modified polymers. For example, BYK-340 (manufactured by Bic Chemie Japan Co., Ltd.) is one such example.

[0036] Surfactants may be used individually or in combination of two or more types.

[0037] Because it provides superior color development, lightfastness, and clogging recovery, the surfactant content is preferably 0.01% to 10% by mass, more preferably 0.05% to 5.0% by mass, and even more preferably 0.1% to 1.0% by mass, relative to the total amount of the ink composition.

[0038] 1.6. Preservatives The ink composition may contain a preservative. The preservative also functions as a fungicide. The preservative may be used alone or in combination of two or more types.

[0039] Examples of such preservatives include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzoisothiazolin-3-one, and 4-chloro-3-methylphenol (such as Bayer's Preventol CMK). Commercially available preservatives can also be used. Examples of commercially available products include the Proxel® series, such as CRL, BND, GXL, XL-2, and TN (all trade names, Lonza Japan Co., Ltd.); and Preventol® CMK (Bayer AG).

[0040] Because it provides superior color development, lightfastness, and clogging recovery, the preservative content is preferably 0.01% to 10% by mass, more preferably 0.03% to 5.0% by mass, and even more preferably 0.05% to 1.0% by mass, relative to the total amount of the ink composition.

[0041] 1.7. Other Ingredients The ink composition may contain various additives that are commonly used in ink compositions, such as solubilizers, viscosity modifiers, pH adjusters, antioxidants, ultraviolet absorbers, oxygen absorbers, rust inhibitors, corrosion inhibitors, and chelating agents. These additives may be used individually or in combination of two or more.

[0042] To obtain superior color development, lightfastness, and clogging recovery properties, the additive content is preferably 0.01% by mass or more and 10% by mass or less in total, relative to the total amount of the ink composition.

[0043] 1.8. Physical properties of the ink composition The viscosity of the ink composition is preferably 1.5 mPa·s to 15 mPa·s at 20°C, more preferably 1.5 mPa·s to 7 mPa·s, and even more preferably 1.5 mPa·s to 5.5 mPa·s.

[0044] From the viewpoint of ensuring appropriate wetting and spreading properties on the recording medium, the upper limit of the surface tension of the ink composition at 25°C is preferably 40 mN / m or less, more preferably 38 mN / m or less, even more preferably 35 mN / m or less, even more preferably 32 mN / m or less, and particularly preferably 30 mN / m or less. Similarly, from the same viewpoint, the lower limit of the surface tension is preferably 15 mN / m or more, more preferably 20 mN / m or more, even more preferably 25 mN / m or more, and even more preferably 27 mN / m or more. In this specification, surface tension can be measured using a surface tension meter CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.) as the surface tension when a platinum plate is wetted with the composition at room temperature and atmospheric pressure. If the surface tension of the ink composition is within the above range, the ejection stability and initial filling performance in inkjet recording can be improved.

[0045] 1.9. Method for producing an ink composition Ink compositions can be prepared by mixing a colorant, a water-soluble organic solvent, water, and optionally a surfactant, preservative, and other components in any order, and removing impurities and foreign matter by filtration or other means as needed. 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.

[0046] 2. Recording Method The inkjet recording method according to this embodiment is performed using an inkjet ink composition. Specifically, the inkjet recording method includes the step of ejecting the ink composition from an inkjet head and adhering it to a recording medium. Next, the recording medium, the inkjet recording apparatus that can be used in the recording method, and the process will be described.

[0047] 2.1 Recording media The recording medium is not particularly limited and may have a recording surface that absorbs liquid or may not have a recording surface that absorbs liquid. Examples of such recording media include paper, film, fabric, metal, glass, and polymers.

[0048] Examples of raw materials for woven fabrics include natural fibers such as cotton, linen, wool, and silk; synthetic fibers such as polypropylene, polyester, acetate, triacetate, polyamide, and polyurethane; and biodegradable fibers such as polylactic acid. Blends of these fibers are also acceptable. The woven fabric may be made from the above-mentioned fibers in any form, such as woven, knitted, or nonwoven fabric, or it may be a blended fabric. Cotton and silk are preferred as raw materials for woven fabrics, and silk is more preferred, as they provide better color development.

[0049] 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 ink composition are ejected from the nozzle holes of the inkjet head at a predetermined timing and in a predetermined volume (mass), thereby adhering the ink composition to the recording medium and forming a predetermined image.

[0050] 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.

[0051] 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.

[0052] The image layer forming means records an image layer by ejecting an ink composition onto the recording surface of a recording medium. The image layer forming means includes an inkjet head equipped with nozzles, and a nozzle row is assigned to each predetermined composition.

[0053] 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.

[0054] 2.3. Each step of the recording method The process of attaching the ink composition to the recording medium can be carried out using an inkjet recording device. Specifically, the ink composition can be attached to the recording medium by filling the inkjet head so that it can be ejected from a predetermined nozzle, and then ejecting it onto the recording medium at a predetermined timing.

[0055] 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.

[0056] The recording method may include other steps. Such steps may include, for example, a step of applying another composition and a washing step.

[0057] In the recording method, since the ink composition according to this embodiment is used, it is possible to record images that have good clogging recovery properties and excellent color development and lightfastness. [Examples]

[0058] The present invention will be described more specifically below using examples and comparative examples. The present invention is not limited in any way by the following examples.

[0059] 1. Preparation of colorants (Preparation of colorants 1-8) Colorants 1-8 were prepared by adjusting the pH of commercially available CIReactive Black 8, ion-exchanging heavy metals, and then purifying it by microfiltration and ultrafiltration. Table 1 shows the mass ratio of compound (B) to compound (A) (compound (B) / compound (A)) and the mass ratio of compound (A) and compound (B) to compound (C) ((compound (A) + compound (B)) / compound (C)) for colorants 1 to 8. The mass ratio of compound (B) to compound (A) was calculated by XRF analysis, and the mass ratio of compound (A) and compound (B) to compound (C) was calculated by LC-MS analysis. Furthermore, in colorants 1 to 8, compound (C) was a mixture of compounds having the structure represented by formula (2). Colorant 7 contained compound (A) and compound (C), but did not contain compound (B). Colorant 8 contained compound (B) and compound (C), but did not contain compound (A).

[0060] [Table 1]

[0061] 2. Preparation of inkjet ink composition (Preparation of Examples 1-10 and Comparative Examples 1-4) Each component was placed in a mixing tank to obtain the composition shown in Table 2. The mixture was then mixed and stirred with a magnetic stirrer for 2 hours, and then filtered through a 5 μm pore size membrane filter to obtain the inkjet ink compositions according to the examples and comparative examples. The values ​​in Table 2 are in mass percent. Deionized water was used and added so that the mass of each ink was 100% by mass.

[0062] Furthermore, the components shown in Table 2 are as follows: [Colorants] • 1-8...Colorants 1-8 obtained from the above preparation. • RBk5…CIReactive Black 5 (commercially available product) • ROR12…CIReactive Orange 12 (commercially available product) • RR24:1…CIReactive Red 24:1 (commercially available product)

[0063] [Penetrating agent (water-soluble organic solvent)] Triethylene glycol monobutyl ether

[0064] [Humidifier (water-soluble organic solvent)] Propylene glycol

[0065] [Surfactants] • PD-002W… Orfin (registered trademark) RD-002W (product name, Nisshin Chemical Industry Co., Ltd.)

[0066] [Preservatives] • XL-2…Proxel (registered trademark) XL-2 (product name, Lonza Japan Co., Ltd.)

[0067] [Table 2]

[0068] 3. Evaluation Method 3.1. Color development Each of the inkjet ink compositions from Examples 1-10 and Comparative Examples 1-4 was filled into cartridges of an inkjet printer PX-930G (product name, manufactured by Seiko Epson Corporation). Then, fabric 1 (100% cotton) and fabric 2 (100% silk) were each inked at a resolution of 720 dpi x 720 dpi with an ink density of 23 mg / inch. 2 An image was formed by applying an inkjet ink composition under these conditions. Each of the fabrics 1 and 2 on which the images were formed was steamed at 102°C for 10 minutes, then washed at 90°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 respective recordings.

[0069] The color reproduction of each obtained recording was evaluated. Specifically, the OD value of Black was measured for each obtained recording using a colorimeter (Gretag Macbeth Spectrolino, X-Rite). Based on the obtained OD values, the color reproduction was evaluated according to the following evaluation criteria. The results are shown in Table 3. (Evaluation Criteria) A: OD value of 0.75 or higher B: OD value is 1.65 or higher and less than 0.75 C:OD value is 1.50 or higher and less than 0.65

[0070] 3.2. Clogging recovery Each of the inkjet ink compositions from Examples 1-10 and Comparative Examples 1-4 was filled into a cartridge of an inkjet printer PX-H6000 (product name, Seiko Epson Corporation). After confirming that there were no clogged nozzles and that all nozzles of the inkjet printer were ejecting ink normally, the printer was turned off in a normal state and left in this state at a temperature of 40°C for one month. For each color, the number of attempts required to achieve normal discharge through recovery by simultaneously aspirating all colors was measured, and the color development was evaluated according to the evaluation criteria below. The results are shown in Table 3. (Evaluation Criteria) A: Normal dispensing occurs immediately after power-on, or normalization occurs after 1 to 4 recovery operations. B: Normalization occurs after 5 to 7 recovery actions. C: Normalization after 8 to 10 recovery actions. D: Normalized after 11 or more recovery actions.

[0071] 3.3. Lightfastness In accordance with ISO 105 B02, the lightfastness of each fabric 1 obtained from the above color development evaluation was measured, and the lightfastness was evaluated according to the following evaluation criteria. The results are shown in Table 3. (Evaluation Criteria) A: Lightfastness grade 5 or higher B: Lightfastness of grade 4 or higher but less than grade 5 C: Lightfastness is less than grade 4.

[0072] [Table 3]

[0073] As shown in Table 3, it was found that the ink composition of this embodiment has excellent color development and lightfastness, can suppress nozzle clogging even if the print head dries out after long-term storage, and can improve clogging recovery.

[0074] Furthermore, a comparison of Example 3 with Examples 4 and 5 revealed that when the colorant contains compound (C) in a specific range in mass ratio ((compound (A) + compound (B)) / compound (C)), it exhibits superior lightfastness and clogging recovery, and tends to have even better color development on cotton and silk fabrics. In particular, it was found that the color development on silk tends to be even better.

[0075] From a comparison between Examples 1 and 6 and Example 7, and between Examples 8 and 9 and Example 10, it was found that by having the colorant content within a specific range, an ink composition with superior color development and lightfastness, as well as even better clogging recovery properties, can be obtained.

Claims

1. It contains a colorant, a water-soluble organic solvent, and water. The aforementioned colorant comprises a compound (A) in which Me is Cr in the structure represented by the following formula (1), and a compound (B) in which Me is Co in the structure represented by the following formula (1). The mass ratio of compound (B) to compound (A) is greater than 0 and less than or equal to 0.

06. The colorant further comprises a compound (C) having a structure represented by the following formula (2), The mass ratio of compound (A) and compound (B) to compound (C) is 4 or more and 20 or less. Inkjet ink composition. 【Chemistry 1】 【Chemistry 2】 (In formula (2), Me is Cr or Co, and X1 and X2 are each independently a chlorine atom or an amino group. However, X1 and X2 are not both chlorine atoms at the same time.)

2. The inkjet ink composition according to claim 1, wherein the mass ratio of compound (B) to compound (A) is 0.005 or more and 0.06 or less.

3. The inkjet ink composition according to claim 1 or 2, wherein the content of the colorant is 5% by mass or less with respect to the total amount of the inkjet ink composition.

4. An inkjet ink composition according to any one of claims 1 to 3, further comprising one or more selected from the group consisting of C.I. Reactive Orange 12 and C.I. Reactive Red 24:1.

Images