Inkjet ink composition

Abstract

To provide an inkjet ink composition that exhibits excellent ejection stability, as well as excellent antibacterial properties against bacteria and antifungal properties against fungi. [Solution] The inkjet ink composition of the present invention comprises compound A represented by the following formula (1) and water, and has a pH of 7.5 or higher at 25°C. Furthermore, the inkjet ink composition preferably contains a humectant with an HSP value of 15.0 or less. Furthermore, the inkjet ink composition contains a polyol compound having three or more OH groups in its molecule, and it is preferable that the content of the polyol compound in the inkjet ink composition is 1.0% by mass or higher. [Formula 1] TIFF2026067528000004.tif27170 (In the formula, R represents a hydrocarbon group with 6 to 12 carbon atoms.)

Description

Technical Field

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

Background Art

[0002] As inks, water-based inks containing water are widely used. Since water causes spoilage, water-based inks require antibacterial and antifungal properties. In recent years, the applications of inkjet printing have expanded, and in addition to office and home printers, it is also applied to commercial printing, textile printing, etc. Inkjet inks are generally used in an alkaline state for ejection stability.

[0003] Therefore, for example, Patent Document 1 discloses an alkaline inkjet ink containing an isothiazolinone-based compound as an antibacterial agent.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the inkjet ink of Patent Document 1 has a problem that while it has antibacterial properties against bacteria, its antifungal properties against fungi are insufficient. Therefore, there is a need to provide an inkjet ink composition that is excellent in ejection stability and has excellent antibacterial properties against bacteria and antifungal properties against fungi.

Means for Solving the Problems

[0006] The present invention has been made to solve the above problems and can be realized as the following application examples. [[ID=?]] [[ID=?]]

[0007] An inkjet ink composition relating to an example of the present invention, The solution contains compound A, represented by the following formula (1), and water, and has a pH of 7.5 or higher at 25°C. [ka] (In the formula, R represents a hydrocarbon group with 6 to 12 carbon atoms.) [Brief explanation of the drawing]

[0008] [Figure 1] Table 1 shows the composition of the inkjet ink compositions of Examples 1 to 12. [Figure 2] Table 2 shows the composition of the inkjet ink compositions of Examples 13-17 and Comparative Examples 1-6. [Figure 3] Table 3 shows the evaluation results of the inkjet ink compositions of Examples 1-17 and Comparative Examples 1-6. [Modes for carrying out the invention]

[0009] The inkjet ink composition of the present invention will be described below based on preferred embodiments. [1] Inkjet ink composition First, the inkjet ink composition according to the embodiment will be described.

[0010] The inkjet ink composition of the present invention comprises compound A represented by the following formula (1) and water, and has a pH of 7.5 or higher at 25°C.

[0011] [ka] (In the formula, R represents a hydrocarbon group with 6 to 12 carbon atoms.)

[0012] This configuration provides an inkjet ink composition that offers excellent ejection stability, as well as superior antibacterial properties against bacteria and antifungal properties against fungi.

[0013] More specifically, compound A is excellent in antibacterial properties against bacteria and antifungal properties against fungi even in an alkaline solution. Therefore, the inkjet ink composition containing the compound A can also have antibacterial properties against bacteria and antifungal properties against fungi in an alkaline solution. Further, since the inkjet ink composition is alkaline, an inkjet ink composition excellent in ejection stability can be provided.

[0014] The above excellent effects are obtained by satisfying all of the above conditions. If even one of the above conditions is not satisfied, the above excellent effects cannot be obtained.

[0015] For example, when compound A is not used, the antibacterial properties of the inkjet ink composition against bacteria and the antifungal properties against fungi decrease. Further, when another compound is used instead of compound A, it does not have both antibacterial properties against bacteria and antifungal properties against fungi. For example, when isothiazolinone is used instead of compound A as an antibacterial agent, antibacterial properties against bacteria are exhibited, but sufficient antifungal properties against fungi cannot be obtained.

[0016] Also, when the number of carbon atoms of the hydrocarbon group represented by R is less than the lower limit value, the hydrophobicity of the R part becomes insufficient, and the antibacterial and antifungal properties of the inkjet ink composition decrease. On the other hand, when the number of carbon atoms of the hydrocarbon group represented by R exceeds the upper limit value, it becomes difficult for compound A to enter cells, and it becomes difficult to exhibit antibacterial and antifungal effects.

[0017] Also, when the pH of the inkjet ink composition is less than the lower limit value, the solubility and dispersibility of the coloring material and resin contained in the inkjet ink composition decrease. Thereby, the ejection stability of the inkjet ink composition decreases.

[0018] In this invention, pH (hydrogen ion concentration) refers to the value obtained by the method in accordance with JIS Z 8802. The pH values ​​used herein are measured at 25°C.

[0019] The constituent components of the inkjet ink composition of the present invention will be described in detail below. [1-1] Antibacterial agents The inkjet ink composition of the present invention contains compound A of formula (1) above as an antibacterial agent. In formula (1), R is a hydrocarbon group having 6 to 12 carbon atoms. Compound A enters cells through the hydrophobic R portion having a hydrocarbon group and exerts antibacterial and antifungal effects.

[0020] The hydrocarbon group represented by R has 6 to 12 carbon atoms, preferably 7 to 10, and more preferably 8. This increases the hydrophobicity of the R portion and makes it easier for compound A to penetrate cells. Therefore, the antibacterial and antifungal properties of the inkjet ink composition can be improved. In addition, the solubility of compound A in water is improved, making it suitable for use as an inkjet ink.

[0021] The hydrocarbon group represented by R may be a cyclic hydrocarbon or a chain hydrocarbon. If it is a chain hydrocarbon, it may have a branched chain, but it is preferably linear. This makes it easier for compound A to enter cells.

[0022] The hydrocarbon group represented by R preferably does not have multiple bonds. The absence of multiple bonds improves the stability of the inkjet ink composition.

[0023] As compound A that satisfies the aforementioned conditions, N-octyldiethanolamine is particularly preferred.

[0024] The content of compound A in the inkjet ink composition is not particularly limited, but is preferably 100 ppm to 1000 ppm, more preferably 250 ppm to 950 ppm, and even more preferably 400 ppm to 900 ppm. This makes it possible to achieve a higher level of balance between the antibacterial and antifungal properties of the inkjet ink composition and the solubility of compound A in water.

[0025] [1-2]Water The inkjet ink composition of the present invention contains water. The water functions as a solvent for dissolving compound A. Furthermore, the water also functions as a solvent and dispersion medium for the components described later.

[0026] The water content in the inkjet ink composition is not particularly limited, but is preferably 50% to 90% by mass, and more preferably 60% to 85% by mass. This makes it possible to achieve particularly excellent storage stability and ejection stability of the inkjet ink composition. Furthermore, when a colorant described later is included, the density of the image formed using the inkjet ink composition can be made particularly high.

[0027] [1-3] Moisturizers The inkjet ink composition of the present invention preferably contains a humectant with an HSP value of 15.0 or less. Compound A contains a hydrocarbon group in the R portion and has low solubility in water. Therefore, by including a humectant with an HSP value of 15.0 or less in the inkjet ink composition, the solubility of compound A in the ink can be improved.

[0028] Here, "HSP value" refers to the Hansen three-dimensional solubility parameter value shown in the following formula (1). In this invention, the notation of units is omitted, but the unit is (cal / cm). 3 ) 0.5The HSP value can be obtained, for example, by referring to the δD, δP, and δH values ​​in the International Chemical Identifier database and calculating it using formula (1).

[0029] HSP value = (δD2 + δP2 + δH2) 0.5 / 4.1868 0.5 ...(1) Dispersion term δD: Energy due to intermolecular dispersion forces Polar term δP: Energy due to intermolecular dipole interaction Hydrogen bond term δH: Energy due to intermolecular hydrogen bonding

[0030] The HSP value of such a humectant contained in the inkjet ink composition is preferably 5.0 to 15.0, and more preferably 8.0 to 14.5. This further improves the solubility of compound A in the ink.

[0031] While not particularly limited, humectants with an HSP value of 15.0 or less include alkanediols, glycol monoethers, and amides. More specifically, examples of alkanediols include propylene glycol, diethylene glycol, triethylene glycol, 1,2-hexanediol, and 1,3-butylene glycol; examples of glycol monoethers include triethylene glycol monobutyl ether and triethylene glycol monomethyl ether; and examples of amides include 1-(2-hydroxyethyl)-2-pyrrolidone, ε-caprolactam, and 2-pyrrolidone. Among these, propylene glycol is preferred as a humectant with an HSP value of 15.0 or less.

[0032] The content of a humectant with an HSP value of 15.0 or less in the inkjet ink composition is preferably 0.1% by mass or more and 35.0% by mass or less, more preferably 1.0% by mass or more and 30.0% by mass or less, and even more preferably 3.0% by mass or more and 25.0% by mass or less. This further improves the solubility of compound A in water. When multiple types of humectants with an HSP value of 15.0 or less are included in the inkjet ink composition, it is preferable that the sum of their content falls within the above range.

[0033] [1-4] Polyol compounds The inkjet ink composition of the present invention preferably contains a polyol compound having three or more OH groups in its molecule.

[0034] Polyol compounds prevent drying of nozzles and other components that eject inkjet ink compositions, thereby improving ejection stability. However, polyol compounds can also serve as a nutrient source for bacteria and fungi, causing the inkjet ink composition to spoil. The inkjet ink composition of the present invention has antibacterial and antifungal properties, so spoilage can be prevented even if polyol compounds are included. Therefore, by including polyol compounds in the inkjet ink composition, it is possible to maintain sufficient antibacterial and antifungal properties while improving ejection stability.

[0035] The polyol compound is not particularly limited, but examples include glycerin, sorbitol, diglycerin, polyglycerin, mannitol, xylitol, erythritol, lactitol, maltitol, galactitol, and trehalose. Among these, glycerin and sorbitol are preferred as polyol compounds.

[0036] The content of the polyol compound in the inkjet ink composition is preferably 1.0% by mass or more, more preferably 5.0% by mass or more and 30.0% by mass or less, and even more preferably 10.0% by mass or more and 25.0% by mass or less. This allows for further improvement of ejection stability while maintaining sufficient antibacterial and antifungal properties. When multiple types of polyol compounds are included in the inkjet ink composition, it is preferable that the sum of their content falls within the above range.

[0037] [1-5] pH adjusters [1-5-1] Acidic pH adjusters Compound A contained in the inkjet ink composition of the present invention exhibits strong alkalinity. Therefore, the inkjet ink composition of the present invention preferably contains an acidic pH adjuster, and more preferably an organic acid. This allows for more appropriate adjustment of the pH of the inkjet ink composition, thereby further improving its antibacterial and antifungal properties.

[0038] Examples of organic acids include carboxylic acids such as adipic acid, citric acid, succinic acid, fumaric acid, lactic acid, tartaric acid, and gluconic acid.

[0039] The content of organic acids in the inkjet ink composition is preferably 0.05% by mass or more and 3.0% by mass or less, and more preferably 0.1% by mass or more and 2.0% by mass or less. This allows for more appropriate adjustment of the pH of the inkjet ink composition. If multiple types of organic acids are included in the inkjet ink composition, it is preferable that the sum of their content is within the above range.

[0040] [1-5-2] Alkaline pH adjusters The inkjet ink composition may contain an alkaline pH adjuster. It is particularly preferable to use it in combination with an acidic pH adjuster. This allows for more appropriate adjustment of the pH of the inkjet ink composition. Note that the alkaline pH adjuster shall not contain compound A.

[0041] Examples of alkaline pH adjusters include alkanolamines other than compound A, alkali metal hydroxides, alkali metal carbonates, and aminosulfonic acids. More specifically, the following compounds can be used. For example, alkanolamines other than compound A include diethanolamine, dimethylethanolamine, diethylethanolamine, triethanolamine, and triisopropanolamine. Alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, and ammonium hydroxide. Alkali metal carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. An example of an aminosulfonic acid is taurine.

[0042] The content of alkaline pH adjusters in the inkjet ink composition is preferably 0.05% by mass or more and 3.0% by mass or less, and more preferably 0.1% by mass or more and 2.0% by mass or less. This allows for more appropriate adjustment of the pH of the inkjet ink composition. When multiple types of alkaline pH adjusters are included in the inkjet ink composition, it is preferable that the sum of their content is within the above range.

[0043] When the content of the alkaline pH adjuster is XA (mass%) and the content of compound A is XB (mass%), the ratio XB / XA is preferably 0.05 to 0.50, more preferably 0.08 to 0.45, and even more preferably 0.10 to 0.40. This allows the pH of the inkjet ink composition to be adjusted more appropriately, resulting in even better antibacterial and antifungal properties.

[0044] [1-6] Colorants The inkjet ink composition of the present invention preferably contains a colorant. This allows the inkjet ink composition to be suitably used for image formation, as described later.

[0045] As colorants, various dyes and pigments can be used. Examples of dyes include disperse dyes, reactive dyes, and acid dyes. Examples of disperse dyes include Disperse Red 60. Examples of reactive dyes include Reactive Orange 13. Examples of acid dyes include Acid Yellow 79 and Acid Yellow 95. Examples of pigments include Pigment Red 122 and Pigment Blue 15:3. Furthermore, although not particularly limited, various dyes and pigments listed in the color index can be used.

[0046] The inkjet ink composition of the present invention preferably contains one or more selected from reactive dyes and colorants containing chlorine atoms in their molecules. Reactive dyes and colorants containing chlorine atoms in their molecules have a corrosive effect on metal components. Therefore, rust prevention measures are necessary when using them. The inkjet ink composition of the present invention has a rust-preventive effect by containing compound A. Thus, the effect of the present invention can be enhanced by including at least one of the reactive dyes and colorants containing chlorine atoms in their molecules in the inkjet ink composition.

[0047] Examples of colorants containing chlorine atoms in their molecules include Reactive Orange 13 and Reactive Blue 49.

[0048] Furthermore, the inkjet ink composition may also contain a non-gold pigment. Gold pigments containing metal have antibacterial and antifungal properties in the pigment itself. On the other hand, non-gold pigments do not have antibacterial and antifungal properties and are therefore more prone to spoilage than gold pigments. Since the inkjet ink composition of the present invention has excellent antibacterial and antifungal properties, it can suppress spoilage even if it contains a non-gold pigment, which tends to have inferior antibacterial and antifungal properties when added to an inkjet ink composition. Therefore, the effects of the present invention can be maintained even in an inkjet ink composition containing a non-gold pigment. Furthermore, it is preferable not to include a gold pigment. Not including a gold pigment means substantially not including one in the inkjet ink composition, and it is preferable that the content of the gold pigment is 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0.1% by mass or less.

[0049] Examples of non-gold pigments include Disperse Red 60, Reactive Orange 13, Acid Yellow 79, and Pigment Red 122. Examples of gold-containing pigments include Pigment Blue 15:3.

[0050] The colorant content in the inkjet ink composition of the present invention is preferably 0.1% by mass or more and 20.0% by mass or less, and more preferably 0.2% by mass or more and 15.0% by mass or less. When the colorant content is within the above range, it is possible to achieve a higher level of balance between ejection stability by the inkjet method and the density of the image formed by the inkjet ink composition. If the inkjet ink composition contains multiple types of colorants, it is preferable that the sum of their content rates falls within the above range.

[0051] [1-7] Other ingredients Inkjet ink compositions may contain components other than those mentioned above. Hereinafter, in this section, such components will also be referred to as "other components."

[0052] Other components include, for example, chelating agents, preservatives other than those mentioned above, flame retardants, various dispersants, resins, rust inhibitors other than those mentioned above, antioxidants, ultraviolet absorbers, oxygen absorbers, solubilizers, penetrating agents, defoaming agents, surfactants, and colorants other than those mentioned above.

[0053] Examples of chelating agents include ethylenediaminetetraacetate. Examples of 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.

[0054] Examples of resins include styrene-acrylic resin, polyethylene wax, and vinyl chloride / vinyl acetate copolymer resins. Including a resin in the inkjet ink composition can improve the fixation of the inkjet ink composition to the recording medium described later.

[0055] Examples of UV absorbers include benzophenone compounds, cinnamic acid compounds, triazine compounds, stilbene compounds, and so-called fluorescent whitening agents (compounds that absorb ultraviolet light and emit fluorescence, such as benzoxazole compounds).

[0056] Examples of defoaming agents include highly oxidized oil compounds, glycerol fatty acid ester compounds, fluorine compounds, silicone compounds, and acetylene compounds.

[0057] Various surfactants can be used, such as anionic surfactants, cationic surfactants, and nonionic surfactants. Examples of nonionic surfactants include silicone surfactants and acetylene glycol surfactants.

[0058] The content of other components in the inkjet ink composition of the present invention is preferably 10.0% by mass or less, and more preferably 5.0% by mass or less.

[0059] [1-8] Other conditions As described above, the pH of the inkjet ink composition of the present invention is 7.5 or higher, but is preferably 7.7 to 11.0, and more preferably 8.0 to 10.0. This allows the effects of the present invention described above to be exhibited more significantly.

[0060] The surface tension (surface tension at 20°C) of the inkjet ink composition of the present invention is preferably 20 mN / m or more and 50 mN / m or less, and more preferably 25 mN / m or more and 40 mN / m or less. The surface tension of the inkjet ink composition can be determined, for example, by measurement in accordance with JIS K3362 using a surface tension meter CBVP-A3 (manufactured by Kyowa Interface Science Co., Ltd.).

[0061] The viscosity (viscosity at 20°C) of the inkjet ink composition of the present invention is preferably 2 mPa·s or more and 20 mPa·s or less. This makes it possible to achieve particularly excellent ejection stability (discharge volume stability, droplet flight characteristics, etc.) and ejection responsiveness (response speed, high-frequency response (frequency characteristics), etc.) of the inkjet ink composition. The viscosity of the inkjet ink composition can be determined by measurement in accordance with JIS Z8809 using a vibrating viscometer.

[0062] [2] Recording method Next, an example of a recording method according to the present invention will be described. This recording method includes the step of ejecting the inkjet ink composition of the present invention by an inkjet method and adhering it to a recording medium. The inkjet ink composition of the present invention has excellent ejection stability, as well as excellent antibacterial properties against bacteria and antifungal properties against fungi. Therefore, by using the inkjet ink composition of the present invention, it is possible to provide a recording method that can stably produce recordings with excellent antibacterial properties against bacteria and antifungal properties against fungi.

[0063] In the recording method according to the present invention, the inkjet ink composition of the present invention is ejected as droplets by an inkjet method, and these droplets are deposited onto a recording medium. This forms a desired image. Multiple types of inkjet ink compositions, for example, multiple types of inkjet ink compositions of the present invention, may be used to form the image.

[0064] Any inkjet method can be used to eject the inkjet ink composition, including, for example, charge deflection methods, continuous methods, piezo methods, bubble jet (registered trademark) methods, and other on-demand methods.

[0065] The recording medium is not particularly limited, but examples include various fabrics, paper such as plain paper, recording mediums with an ink-receiving layer, such as inkjet-specific paper or coated paper, and plastic films made of various plastics such as polyethylene terephthalate and polypropylene.

[0066] In the recording method of the present invention, not only the inkjet ink composition of the present invention but also other ink compositions may be used in combination.

[0067] Furthermore, the recording method of the present invention may include other steps in addition to those described above. For example, these may include steps of applying a coating layer to the recording medium, heating the recording medium, and cleaning the recording medium.

[0068] [3] Records The recording material according to the present invention is manufactured using the inkjet ink composition of the present invention described above, and can be manufactured using the recording method described above. This makes it possible to provide a recording material with excellent antibacterial properties against bacteria and antifungal properties against fungi.

[0069] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto. [Examples]

[0070] Next, specific examples of the present invention will be described, but the present invention is not limited thereto. In the following examples, unless the temperature conditions are specified, the processing and measurements were performed at room temperature (25°C).

[0071] [4] Preparation of inkjet ink compositions (Example 1) By mixing each component in predetermined ratios, an inkjet ink composition with the composition shown in Figure 1 was obtained.

[0072] (Examples 2-17) An inkjet ink composition was prepared in the same manner as in Example 1 described above, except that the types of components used in the preparation of the inkjet ink composition and the mixing ratio of each component were changed to obtain the compositions shown in Figures 1 and 2.

[0073] (Comparative Examples 1-6) An inkjet ink composition was prepared in the same manner as in Example 1 described above, except that the types of components used in the preparation of the inkjet ink composition and the mixing ratio of each component were changed to obtain the composition shown in Figure 2.

[0074] The compositions of the inkjet ink compositions for each example and comparative example are summarized in Figures 1 and 2. In the composition column of Figures 1 and 2, the unit of the numerical value is mass%, and columns without a numerical value or with a "-" notation mean that the substance is not contained. In the table, antibacterial agents other than compound A are indicated as "other antibacterial agents," and polyol compounds having three or more OH groups in the molecule are indicated as "polyol compounds." Furthermore, the solid content of the silicone-based surfactant Silface SAG503A (trade name, manufactured by Nisshin Chemical Industry Co., Ltd.) is indicated as "Silface SAG503A," and the solid content of the silicone-based surfactant BYK-315N (trade name, manufactured by BYK Chemie Co., Ltd.) is indicated as "BYK-315N." The solid content of Olphine E1010 (trade name, manufactured by Nisshin Chemical Industry Co., Ltd.), an acetylene glycol-based surfactant, is indicated as "Olfine E1010," and the solid content of Olphine PD002W (trade name, manufactured by Nisshin Chemical Industry Co., Ltd.), an acetylene glycol-based surfactant, is indicated as "Olfine PD002W." The solid content of Joncryl 67 (trade name, manufactured by BASF), a resin particle composed of materials containing styrene-acrylic resin, is indicated as "Joncryl 67," the solid content of CA-383 (trade name, manufactured by BASF), a resin particle composed of materials containing polyethylene wax, is indicated as "CA-383," and the solid content of Solvine CLL (trade name, manufactured by Nisshin Chemical Industry Co., Ltd.), a resin particle composed of materials containing vinyl chloride / vinyl acetate copolymer resin, is indicated as "Solvine CLL."

[0075] [5] Evaluation of inkjet ink compositions [5-1] Solubility For each example and comparative example, inkjet ink compositions were prepared by removing the colorants and resins from their respective compositions, and these were stirred with a magnetic stirrer (rotation speed 200 rpm) for 20 minutes. The solubility of each component was then visually inspected and evaluated.

[0076] A: Colorless and transparent C: Cloudiness or separation

[0077] [5-2] Antibacterial (bacterial) In 10 mL of the inkjet ink composition of each example and each comparative example, 10 × 108 A test bacterial suspension of Escherichia coli, prepared to a CFU / mL concentration, was inoculated at 0.1 mL and allowed to stand at 25°C for 24 hours. A 10-fold dilution series of the inkjet ink composition after standing was prepared using SCDLP liquid medium, inoculated onto standard agar plates, and cultured at 30°C for 48 hours. After culturing, the number of viable cells was calculated based on the number of colonies formed. The initial bacterial count was calculated using the viable cell count measurement result of the test bacterial suspension and the inoculation amount. Three measurements were taken for each example and comparative example, and the average value was used as the measurement result to evaluate the antibacterial activity according to the following evaluation criteria.

[0078] A: The number of viable bacteria is below the detection limit. B: Viable cell count is above the detection limit, but less than 50% of the initial bacterial count. C: Viable bacterial count is 50% or more of the initial bacterial count.

[0079] [5-3] Antifungal (fungal) In 10 mL of the inkjet ink composition of each example and each comparative example, 10 × 10 8 0.1 mL of a test bacterial suspension of Penicillium funiculosum, prepared to a CFU / mL concentration, was inoculated and allowed to stand at 25°C for 24 hours. A 10-fold dilution series of the inkjet ink composition after standing was prepared using SCDLP liquid medium, inoculated onto standard agar plates, and cultured at 20°C for 3 days. After culturing, the number of viable cells was calculated based on the number of colonies formed. The initial bacterial count was calculated using the viable cell count measurement result of the test bacterial suspension and the inoculation amount. Three measurements were taken for each example and comparative example, and the average value was used as the measurement result to evaluate the antifungal activity according to the following evaluation criteria.

[0080] A: The number of viable bacteria is below the detection limit. B: Viable cell count is above the detection limit, but less than 50% of the initial bacterial count. C: Viable bacterial count is 50% or more of the initial bacterial count.

[0081] [5-4] Discharge stability The ink cartridges of the PX-G930 inkjet recording device (manufactured by Seiko Epson Corporation) were filled with the inkjet ink compositions of each example and comparative example, and it was confirmed that ink could be ejected from all nozzles. Subsequently, the inkjet head was displaced from the position of the cap provided on the inkjet recording device, and the head was left uncapped for 5 days in an environment of 40°C and 20% humidity.

[0082] After standing, the inkjet head was cleaned by suctioning ink from the nozzles at room temperature, repeating the suction operation three times in the order of 4g, 2g, and 2g. Based on the number of nozzles that recovered without failure to eject after the suction operation, the ejection stability was evaluated according to the following evaluation criteria.

[0083] A: No unrecovered nozzles B: 1 to 10 unrecovered nozzles C: 11 or more unrecovered nozzles

[0084] [5-5] Rust prevention Tests and grade determinations were conducted in accordance with the "Method for Measuring the Degree of Rust Occurrence" described in JIS K2246:2018 "Rust-Preventive Oil". The environmental conditions for storage were a temperature of 80°C, a humidity of 95%, and 10 days.

[0085] A: Grades A-D C:E class These evaluation results are summarized in Figure 3.

[0086] As is clear from Figure 3, the inkjet ink compositions of each example exhibited excellent solubility, antibacterial properties against bacteria, antifungal properties against fungi, ejection stability, and rust prevention. In contrast, the inkjet ink compositions of each comparative example did not yield satisfactory results.

Claims

1. The compound A, represented by the following formula (1), and water are included. An inkjet ink composition having a pH of 7.5 or higher at 25°C. 【Chemistry 1】 (In the formula, R is a hydrocarbon group with 6 to 12 carbon atoms.)

2. The inkjet ink composition according to claim 1, comprising a humectant with an HSP value of 15.0 or less.

3. It contains a polyol compound having three or more OH groups in the molecule, The inkjet ink composition according to claim 1 or 2, wherein the content of the polyol compound in the inkjet ink composition is 1.0% by mass or more.

4. The inkjet ink composition according to claim 1 or 2, wherein R is a hydrocarbon group having 8 carbon atoms.

5. The inkjet ink composition according to claim 1 or 2, wherein the content of compound A in the inkjet ink composition is 100 ppm or more and 1000 ppm or less.

6. An inkjet ink composition according to claim 1 or 2, comprising an organic acid.

7. An inkjet ink composition according to claim 1, comprising a colorant.

8. The inkjet ink composition according to claim 7, wherein the colorant includes a non-gold colorant.

9. The inkjet ink composition according to claim 7 or 8, wherein the colorant comprises one or more selected from reactive dyes and colorants containing chlorine atoms in their molecules.

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