inkjet ink

Abstract

To provide an inkjet ink that achieves both high image density and excellent storage stability. [Solution] The inkjet ink contains a pigment, a pigment-coating resin, a hydrophobic solvent with a LogP of 0.03 to 0.51, and water. In the above inkjet ink, the ratio of the pigment-coating resin content to the pigment content is 8.0% by mass to 12% by mass. In the above inkjet ink, the hydrophobic solvent content is 10% by mass to 30% by mass. In the above inkjet ink, the average particle size of the pigment dispersion composed of the pigment and the pigment-coating resin when diluted 100 times by mass with a mixed solution of 50 parts by mass of the hydrophobic solvent and 50 parts by mass of water is 618 nm or more.

Description

Technical Field

[0001] The present invention relates to ink for inkjet.

Background Art

[0002] Patent Documents 1 and 2 disclose inkjet inks containing pigments. Pigments contained in inkjet inks include self-dispersing pigments that are individually dispersed in a solvent and resin-dispersed pigments that are coated with a resin and dispersed in a solvent through the resin. In resin-dispersed pigments, steric repulsion occurs in the solvent during storage, so aggregation is less likely to occur than in self-dispersing pigments. Therefore, resin-dispersed pigments are likely to obtain high storage stability. On the other hand, in resin-dispersed pigments, steric repulsion occurs even after landing on a recording medium when forming an image, so aggregation is less likely to occur on the recording medium than in self-dispersing pigments. Therefore, resin-dispersed pigments are likely to penetrate into the interior of fibers together with the solvent, and as a result, the image density is likely to be impaired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the inkjet inks described in Patent Documents 1 and 2, in a configuration using a resin-dispersed pigment, a new solid component is blended to enhance the aggregability of the pigment on the recording medium. However, by blending a new solid component into the ink, the manufacturing cost increases and the ejection stability in the recording head is likely to be impaired.

[0005] In view of the above circumstances, the object of the present invention is to provide an inkjet ink that can achieve both high image density and storage stability. [Means for solving the problem]

[0006] To achieve the above objective, an inkjet ink according to one embodiment of the present invention contains a pigment, a pigment-coated resin, a hydrophobic solvent with a LogP of 0.03 or more and 0.51 or less, and water. In the above-mentioned inkjet ink, the ratio of the pigment-coating resin content to the pigment content is 8.0% by mass or more and 12% by mass or less. In the above-mentioned inkjet ink, the hydrophobic solvent content is 10% by mass or more and 30% by mass or less. In the above-mentioned inkjet ink, the average particle size of the pigment dispersion, which is composed of the pigment and the pigment-coating resin, is 618 nm or larger when diluted 100 times by mass with a mixed solution of 50 parts by mass of the hydrophobic solvent and 50 parts by mass of water.

[0007] The hydrophobic solvent may include at least one of triethylene glycol monobutyl ether and 3-methyl-1,5-pentanediol.

[0008] The content of the hydrophobic solvent may be 20% by mass or more and 30% by mass or less. [Effects of the Invention]

[0009] The present invention can provide an inkjet ink that can achieve both high image density and stable storage. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will now be described. In this invention, "acrylic" and "methacrylic" are collectively referred to as "(meth)acrylic," meaning that "(meth)acrylic" includes both "acrylic" and "methacrylic."

[0011] [Inkjet ink composition] (Schematic configuration) An inkjet ink according to one embodiment of the present invention (hereinafter also simply referred to as "ink") contains a pigment, a pigment-coated resin, a hydrophobic solvent, and water. The ink according to this embodiment is an aqueous ink that is ejected from the recording head of an inkjet recording device onto a recording medium to form an image on the recording medium. The recording medium on which an image is formed with the ink according to this embodiment is a recording medium that is permeable to ink and is composed of fibers such as cellulose fibers, and examples include plain paper, copy paper, recycled paper, thin paper, and thick paper.

[0012] The ink according to this embodiment is designed so that the pigment does not easily aggregate in the solvent during storage, but when it adheres to the recording medium and drying progresses, the pigment tends to aggregate on the recording medium as the concentration of the hydrophobic solvent increases. As a result, the ink according to this embodiment can improve the image density of the image formed on the recording medium by remaining on the surface without penetrating the fibers constituting the recording medium, while ensuring high storage stability. In other words, the ink according to this embodiment can achieve both image density and storage stability.

[0013] (Hydrophobic solvent) In this embodiment, the ink uses a hydrophobic solvent which is a water-soluble organic solvent with an octanol / water partition coefficient LogP (hereinafter also simply referred to as LogP) of 0.03 or more and 0.51 or less. In this embodiment, by setting the LogP of the hydrophobic solvent to 0.03 or more, the hydrophobicity increases as drying progresses on the recording medium, making it easier to obtain high pigment cohesiveness. In addition, in this embodiment, by setting the LogP of the hydrophobic solvent to 0.51 or less, it is easier to obtain high pigment dispersibility in the solvent. In this embodiment, for water-soluble organic solvents for which literature values ​​can be obtained, the literature value is used as the LogP, and for water-soluble organic solvents for which literature values ​​cannot be obtained, a value calculated by calculation software (for example, "ChemDraw" from PerkinElmer) can be used.

[0014] The hydrophobic solvent incorporated into the ink according to this embodiment preferably contains at least one of triethylene glycol monobutyl ether (LogP: 0.44) and 3-methyl-1,5-pentanediol (LogP: 0.35). In the ink according to this embodiment, the hydrophobic solvent content is preferably 10% by mass or more and 30% by mass or less, and preferably 20% by mass or more and 30% by mass or less. In the ink according to this embodiment, by setting the hydrophobic solvent content to 10% by mass or more, the hydrophobicity increases as drying progresses on the recording medium, making it easier to obtain high pigment cohesiveness. In addition, in the ink according to this embodiment, by setting the hydrophobic solvent content to 30% by mass or less, it is easier to obtain high pigment dispersibility in the solvent. In the ink according to this embodiment, if multiple types of hydrophobic solvents are included, the total content of the multiple types of hydrophobic solvents shall be considered as the hydrophobic solvent content.

[0015] (Pigment) In the ink according to this embodiment, for example, yellow pigment, orange pigment, red pigment, blue pigment, purple pigment, or black pigment can be used as the pigment. Examples of yellow pigments include CI Pigment Yellow 74, 93, 95, 109, 110, 120, 128, 138, 139, 151, 154, 155, 173, 180, 185, or 193. Examples of orange pigments include CI Pigment Orange 34, 36, 43, 61, 63, or 71. Examples of red pigments include CI Pigment Red 122 or 202. Examples of blue pigments include CI Pigment Blue 15 or 15:3. Examples of purple pigments include CI Pigment Violet 19, 23, or 33. Examples of black pigments include CI Pigment Black 7. In the ink according to this embodiment, the pigment content is preferably 3.0% by mass or more and 20.0% by mass or less, and more preferably 7.0% by mass or more and 12.0% by mass or less.

[0016] (Pigment-coated resin) The ink according to this embodiment is formulated with a pigment-coating resin to enhance the dispersibility of the pigment in the solvent. The pigment-coating resin is made up of fine resin particles and suppresses pigment aggregation by adsorbing onto the surface of the pigment. In an ink formulated with a pigment-coating resin, the pigment and the pigment-coating resin together constitute a pigment dispersion. The pigment dispersion is composed of, for example, a core containing the pigment and a pigment-coating resin coating the core. In the case of the pigment-coating resin, a portion may be dispersed in the solvent without adsorbing onto the surface of the pigment.

[0017] The pigment-coated resin can be appropriately selected from known pigment-coated resins. The pigment-coated resin may be a random polymer or a block polymer. Specific examples of pigment-coated resins include polyester, polyurethane, (meth)acrylic acid, styrene-(meth)acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic acid half-ester copolymer, vinylnaphthalene-(meth)acrylic acid copolymer, or vinylnaphthalene-maleic acid copolymer. Styrene-(meth)acrylic acid copolymer is a resin containing units derived from styrene and units derived from (meth)acrylic acid, (meth)acrylic acid ester, or methacrylic acid ester. Examples of styrene-(meth)acrylic acid copolymers include styrene-(meth)acrylic acid-(meth)acrylic acid alkyl ester copolymer, styrene-methacrylic acid-methacrylic acid alkyl ester-(meth)acrylic acid alkyl ester copolymer, styrene-(meth)acrylic acid copolymer, styrene-maleic acid-(meth)acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, or styrene-methacrylic acid alkyl ester copolymer. Among these pigment-coated resins, styrene-(meth)acrylic acid copolymer is preferred due to its ease of preparation and excellent pigment dispersion effect, styrene-methacrylic acid-alkyl methacrylate-(meth)acrylic acid copolymer is more preferred, and methacrylic acid-methyl methacrylate-(meth)acrylate-butyl styrene copolymer is even more preferred.

[0018] The neutralization rate of the pigment-coated resin is preferably 20% or more and 100% or less, more preferably 30% or more and 60% or less. The neutralization rate of the pigment-coated resin is obtained as the percentage (100×(MB / MA)) of the actual amount of the basic compound used in the dispersion treatment step (MB) with respect to the theoretical value (MA) of the amount of the basic compound required to completely neutralize the pigment-coated resin.

[0019] The acid value of the pigment-coated resin is preferably 50 mgKOH / g or more and 300 mgKOH / g or less, more preferably 75 mgKOH / g or more and 275 mgKOH / g or less. By setting the acid value of the pigment-coated resin to 50 mgKOH / g or more, crosslinking with the crosslinking agent described below can be easily performed. By setting the acid value of the pigment-coated resin to 300 mgKOH / g or less, high storage stability in the ink according to this embodiment can be obtained. The acid value of the pigment-coated resin is obtained by measurement in accordance with JIS K 0070:1992 (Test Methods for Acid Value, Saponification Value, Ester Value, Iodine Value, Hydroxyl Value and Unsaponifiable Matter of Chemical Products).

[0020] The mass average molecular weight (Mw) of the pigment-coated resin is preferably 3000 or more and 180000 or less, more preferably 5000 or more and 15000 or less. By setting the mass average molecular weight of the pigment-coated resin within this range, the efficiency of coating the surface of the pigment is improved, and the pigment dispersion and ink are easily maintained at an appropriate viscosity. The mass average molecular weight of the pigment-coated resin is obtained by measurement using gel permeation chromatography (HLC-8020GPC manufactured by Tosoh Corporation) under the following conditions. Column: "TSKgel SuperMultiporeHZ-H" (semi-micro column with 4.6 mm I.D. × 15 cm) manufactured by Tosoh Corporation Number of columns: 3 Eluent: Tetrahydrofuran Flow rate: 0.35 mL / min Sample injection volume: 10 μL Measurement temperature: 40 °C Detector: IR detector The calibration curve is created by selecting seven types of TSKgel standard polystyrene manufactured by Tosoh Corporation—F-40, F-20, F-4, F-1, A-5000, A-2500, and A-1000—along with n-propylbenzene.

[0021] In the ink according to this embodiment, the ratio of the pigment-coating resin content to the pigment content is 8.0% by mass or more and 12% by mass or less. In the ink according to this embodiment, setting the ratio of the pigment-coating resin content to the pigment content to 8.0% by mass makes it easier to obtain high dispersibility of the pigment in the solvent. Furthermore, in the ink according to this embodiment, setting the ratio of the pigment-coating resin content to the pigment content to 12% by mass or less makes it easier to obtain high aggregation of the pigment on the recording medium.

[0022] The ink according to this embodiment is designed so that the pigment dispersion, composed of the pigment and the pigment coating resin, readily aggregates in a hydrophobic environment, assuming a state where drying has progressed on the recording medium. Specifically, the ink is diluted 100 times by mass with a hydrophobic solvent-rich mixed solution obtained by mixing 50 parts by mass of hydrophobic solvent and 50 parts by mass of water, thereby creating a hydrophobic environment around the pigment dispersion contained in the ink. The ink according to this embodiment is designed so that the average particle size of the pigment dispersion in this hydrophobic environment is 618 nm or more. Furthermore, it is preferable that the ink according to this embodiment is designed so that the average particle size of the pigment dispersion in this hydrophobic environment is 716 nm or less.

[0023] In the ink according to this embodiment, by setting the average particle size of the pigment dispersion in a hydrophobic environment to 618 nm or more, the pigment dispersion aggregates as drying progresses on the recording medium, preventing it from penetrating into the fibers constituting the recording medium along with the solvent, and instead remaining on the surface of the fibers. As a result, the amount of pigment visible in the image formed on the recording medium increases in the ink according to this embodiment, making it possible to form an image with high image density. The average particle size of the pigment dispersion can be measured as the cumulant diameter using the "nanoSAQLA" multi-sample nanoparticle diameter measurement system manufactured by Otsuka Electronics Co., Ltd.

[0024] In inks containing multiple types of hydrophobic solvents with a LogP of 0.03 to 0.51, when preparing a mixed solution, a hydrophobic solvent containing multiple types of hydrophobic solvents in the same proportions as the ink is used. For example, in the case of an ink containing 5% by mass of hydrophobic solvent p, 12% by mass of hydrophobic solvent q, and 1% by mass of hydrophobic solvent r, a mixed hydrophobic solvent is prepared by mixing 5% by mass of hydrophobic solvent p, 12% by mass of hydrophobic solvent q, and 1% by mass of hydrophobic solvent r, and the mixed solution is prepared by mixing 50 parts by mass of the mixed hydrophobic solvent with 50 parts by mass of water.

[0025] (water) In the ink according to this embodiment, for example, ion-exchanged water, purified water, or distilled water can be used as water. In the ink according to this embodiment, from the viewpoint of drying properties and ejection reliability, the water content is preferably 25.0% by mass or more and 80.0% by mass or less, and more preferably 35.0% by mass or more and 60.0% by mass or less.

[0026] (Other ingredients) The ink according to this embodiment may contain components other than those listed above, as needed. For example, the ink according to this embodiment may contain a surfactant. Surfactants have the effect of increasing the penetration (wetting) of the ink of the present invention into the recording medium. Examples of surfactants that can be used in the ink according to this embodiment include anionic surfactants, cationic surfactants, and nonionic surfactants. Nonionic surfactants are preferred as surfactants. Examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl sucrose, and ethylene oxide adducts of acetylene glycol. Ethylene oxide adducts of acetylene glycol are preferred as nonionic surfactants.

[0027] Furthermore, in addition to surfactants, the ink according to this embodiment may contain various additives such as dissolving stabilizers, antioxidants, viscosity modifiers, pH adjusters, and antifungal agents, as needed.

[0028] [Examples and Comparative Examples] Ink preparation and evaluation were carried out as examples and comparative examples of the present invention. Note that the following examples are merely examples of the present invention, and the configuration of the present invention is not limited to the configurations of these examples.

[0029] (Preparation of pigment-coated resin) A methacrylic acid-methyl methacrylate-butyl acrylate-styrene copolymer was prepared as the pigment coating resin to be used in the inks of the examples and comparative examples. First, a stirrer, a nitrogen inlet tube, a condenser, and a dropping funnel were set up in a four-necked flask. Next, 100 parts by mass of isopropyl alcohol and 300 parts by mass of methyl ethyl ketone were placed in the flask. The contents of the flask were heated under reflux at 70°C while bubbling nitrogen into it.

[0030] Next, solution L1 was prepared. First, 50 parts by mass of styrene, 10.0 parts by mass of methacrylic acid, 30.0 parts by mass of methyl methacrylate, 10.0 parts by mass of butyl acrylate, and 0.4 parts by mass of azobisisobutyronitrile (AIBN, polymerization initiator) were mixed to obtain solution L1, which is a monomer solution. Solution L1 was added dropwise to the flask over 2 hours while the flask contents were heated under reflux at 70°C. After the dropwise addition, the flask contents were heated under reflux at 70°C for a further 6 hours.

[0031] Next, solution L2 was prepared. First, 0.2 parts by mass of AIBN and 150.0 parts by mass of methyl ethyl ketone were mixed to obtain solution L2. Solution L2 was added dropwise to a flask over 15 minutes. After addition, the contents of the flask were heated under reflux at 70°C for a further 5 hours. In this way, a pigment-coated resin (styrene-(meth)acrylic resin) was obtained.

[0032] Subsequently, while heating the pigment-coated resin in a 70°C bath, an amount of sodium hydroxide aqueous solution necessary for neutralization was added to the pigment-coated resin. More specifically, an amount of sodium hydroxide aqueous solution equal to 1.1 times the neutralization equivalent mass was added to the pigment-coated resin. In this way, an aqueous solution of the pigment-coated resin neutralized with sodium hydroxide was obtained. The pH of the obtained aqueous solution of the pigment-coated resin was 8.

[0033] (Preparation of pigment dispersion) Pigment dispersions b1 to b5, used in the preparation of the inks in the examples and comparative examples, were prepared.

[0034] • Pigment dispersions b1-b4 Pigment (carbon black "MONARCH 800" manufactured by CABOT), pigment-coating resin, and water (the total of water contained in the sodium hydroxide aqueous solution used to neutralize the pigment-coating resin, the water produced by the neutralization reaction, and newly added water) were mixed in the proportions shown in Table 1. After pre-dispersion with a disperser, the final dispersion was carried out with a bead mill until the average particle size reached 100 nm, yielding pigment dispersions b1 to b4. Table 1 also shows the mass ratio of pigment-coating resin content to pigment content in pigment dispersions b1 to b4.

[0035] [Table 1]

[0036] Furthermore, in pigment dispersion b4, the average particle size of the pigment dispersion did not reach 100 nm. This is thought to be because, in pigment dispersion b4, where the ratio of the pigment-coating resin content to the pigment content was less than 8.0% by mass, the degree of pigment coating was insufficient. For this reason, ink preparation and evaluation using pigment dispersion b4 were not performed.

[0037] • Pigment dispersion b5 100 g of pigment (carbon black "MONARCH 800" manufactured by CABOT) was added to 3,000 mL of 2.5 N (normal) sodium hypochlorite aqueous solution to obtain a dispersion. The obtained dispersion was reacted (oxidized) for 12 hours at a temperature of 60°C and a speed of 300 rpm while stirring to impart carboxyl groups to the surface of the carbon black. This resulted in a dispersion containing carbon black with carboxyl groups on its surface (oxidized carbon black). This dispersion was filtered to separate the oxidized carbon black. 100 mL of sodium hydroxide aqueous solution (0.5 mol) was added to the filtered oxidized carbon black to neutralize it and obtain a mixture. Next, the obtained mixture was ultrafiltered to obtain a dispersion containing neutralized oxidized carbon black (black self-dispersing pigment). Subsequently, the dispersion containing the black self-dispersing pigment was further ultrafiltered using a dialysis membrane with ion-exchanged water, and the moisture content was adjusted so that the solid content concentration was 20% by mass (water content 80% by mass) to obtain pigment dispersion b5. The median diameter (D50) of the black self-dispersing pigment was 100 nm.

[0038] (Ink preparation) The inks for the examples and comparative examples were prepared by mixing a pigment dispersion, a water-soluble organic solvent, a surfactant, and deionized water in a container and passing the mixture through a filter (pore size: 5 μm). The inks for the examples and comparative examples used the four types of water-soluble organic solvents shown in Table 2. All of the water-soluble organic solvents shown in Table 2 are manufactured by Tokyo Chemical Industry Co., Ltd. Table 2 also shows the LogP values ​​for each water-soluble organic solvent. Among the water-soluble organic solvents shown in Table 2, triethylene glycol monobutyl ether (BTG) and 3-methyl-1,5-pentanediol (MPD) are hydrophobic solvents with a LogP value of 0.03 to 0.51. Furthermore, the inks for both the examples and comparative examples used "Surfinol® 420," manufactured by Nisshin Chemical Industry Co., Ltd., as the surfactant.

[0039] [Table 2]

[0040] (Measurement of average particle size of pigment dispersions in a hydrophobic environment) A hydrophobic solvent used for each ink was prepared, and a mixed solution was created by mixing 50 parts by mass of the hydrophobic solvent with 50 parts by mass of water. Diluted solutions were prepared by diluting each ink 100 times by mass with the mixed solution. For each ink, the average particle size of the pigment dispersion in the diluted solution was measured using the "nanoSAQLA" multi-sample nanoparticle size measurement system manufactured by Otsuka Electronics Co., Ltd.

[0041] (Ink evaluation) The inks used in the examples and comparative examples were evaluated for image density and storage stability.

[0042] • Method for evaluating image density Image density was evaluated by forming a solid image on a recording medium (Fujifilm Business Innovation Co., Ltd. "C2") using an inkjet recording device equipped with a 600 dpi recording head. The reflectance density of the formed solid image was measured using a fluorescence spectrophotometer (Konica Minolta, Inc. "FD-5"). For each ink, the reflectance density was used as the evaluation value for image density. Each ink's evaluation value was evaluated according to the following A and B criteria. For image density, inks with an evaluation of A were considered acceptable, and inks with an evaluation of B were considered unacceptable. A (good): 1.20 or more B (Poor): Less than 1.20

[0043] ·Storage stability Each ink was placed in a sealed container. The containers were then placed in a constant temperature incubator set to 60°C and kept there for four weeks. After four weeks, the inks in the containers were assessed to determine whether or not they had gelled. Each ink was evaluated according to the following criteria A and B. In terms of storage stability, inks with an A rating were considered successful, and inks with a B rating were considered unsuccessful. A (Good): Not gelled B (Defective): Gelated

[0044] (Examples 1-5) Table 3 shows the content of pigment, water-soluble organic solvent, surfactant, and ion-exchanged water in the inks of Examples 1 to 5. All values ​​in Table 3 are in "mass%".

[0045] [Table 3]

[0046] For the inks of Examples 1 to 5, the average particle size of the pigment dispersion in a hydrophobic environment was measured, and the image density and storage stability were evaluated. Table 4 shows the measurement results of the average particle size of the pigment dispersion in a hydrophobic environment, as well as the evaluation results of the image density and storage stability for the inks of Examples 1 to 5. In all of the inks of Examples 1 to 5, the average particle size of the pigment dispersion in a hydrophobic environment was 618 nm or larger, and both image density and storage stability passed the evaluation.

[0047] [Table 4]

[0048] (Comparative Examples 1-5) Table 5 shows the pigment, water-soluble organic solvent, surfactant, and ion-exchanged water content in the inks of Comparative Examples 1 to 5. Note that all values ​​in Table 5 are in "mass%".

[0049] [Table 5]

[0050] The ink according to Comparative Example 1 differs from the ink according to the above example in that it uses a pigment dispersion b3 in which the ratio of pigment coating resin content to pigment content is greater than 12.0% by mass. The ink according to Comparative Example 2 differs from the ink according to the above example in that it uses a pigment dispersion b5 that does not contain a pigment coating resin. The ink according to Comparative Example 3 differs from the ink according to the above example in that the hydrophobic solvent content is less than 10% by mass. The ink according to Comparative Example 4 differs from the ink according to the above example in that the hydrophobic solvent content is greater than 30% by mass. The ink according to Comparative Example 5 differs from the ink according to the above example in that it uses a hydrophobic solvent with a LogP greater than 0.51.

[0051] For the inks related to Comparative Examples 1 to 5, the average particle size of the pigment dispersion in a hydrophobic environment was measured, and the image density and storage stability were evaluated. Table 6 shows the measurement results of the average particle size of the pigment dispersion in a hydrophobic environment, as well as the evaluation results of the image density and storage stability for the inks related to Comparative Examples 1 to 5. In the ink related to Comparative Example 1, the average particle size of the pigment dispersion in a hydrophobic environment was less than 618 nm. Comparative Examples 1 and 3 failed in terms of image density. In the inks related to Comparative Examples 2, 4, and 5 failed in terms of storage stability.

[0052] [Table 6]

Claims

1. It contains a pigment, a pigment-coated resin, a hydrophobic solvent with a LogP of 0.03 or more and 0.51 or less, and water. The ratio of the content of the pigment-coated resin to the content of the pigment is 8.0% by mass or more and 12% by mass or less. The content of the hydrophobic solvent is 10% by mass or more and 30% by mass or less. The average particle size of the pigment dispersion, composed of the pigment and the pigment-coating resin, when diluted 100 times by mass with a mixed solution of 50 parts by mass of the hydrophobic solvent and 50 parts by mass of water, is 618 nm or larger. Inkjet ink.

2. An inkjet ink according to claim 1, The hydrophobic solvent comprises at least one of triethylene glycol monobutyl ether and 3-methyl-1,5-pentanediol. Inkjet ink.

3. An inkjet ink according to claim 1 or 2, The content of the hydrophobic solvent is 20% by mass or more and 30% by mass or less. Inkjet ink.

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