Aqueous ink jet ink composition and recording method

Abstract

To provide an inkjet ink composition excellent in storage stability.SOLUTION: The water-based inkjet ink composition contains a coloring material and fulvic acid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a water-based ink-jet ink composition and a recording method. [Background technology]

[0002] Inkjet recording methods are capable of recording high-resolution images using relatively simple equipment and have been rapidly developing in various fields. In recent years, environmental issues have become a concern, and environmentally friendly ink compositions have been developed by using materials derived from natural products. For example, Patent Document 1 discloses an inkjet ink composition that contains a chelating agent with excellent biodegradability and has excellent long-term ejection stability, and is characterized by containing a specific chelating agent and water and having a pH (hydrogen ion exponent) of more than 7 and not more than 10. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-185239 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for further improvements in the storage stability and ejection stability of such ink-jet ink compositions. [Means for solving the problem]

[0005] The water-based ink-jet ink composition of the present invention contains a colorant and a fulvic acid.

[0006] The recording method of the present invention includes an application step of ejecting the ink-jet ink composition from an ink-jet head and applying it to a recording medium.

[0007] The recorded matter of the present invention is a recording medium to which the ink composition is attached. [Brief explanation of the drawings]

[0008] [Figure 1] Table 1 shows the evaluation results of the examples. [Figure 2] Table 2 shows the evaluation results of the comparative example and the reference example. [Figure 3] Table 3 shows the evaluation results of Example 9, Comparative Examples 2 and 3, and Reference Example 1. [Figure 4] FIG. 2 is a diagram illustrating an example of a recording apparatus used in the recording method of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. In the drawings, the same elements are given the same reference numerals, and redundant explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0010] 1. Inkjet ink composition The inkjet ink composition according to this embodiment (hereinafter also simply referred to as the "ink composition") contains a coloring material and fulvic acid.

[0011] The ink composition may contain metal ions derived from its constituent materials or from components that come into contact with the ink composition, such as an ink composition container, an ink composition flow path, or a printer head. Such metal ions can cause insoluble salts or foreign matter to form in the ink composition, thereby reducing the storage stability and ejection stability of the ink composition. For this reason, a chelating agent may be used in the ink composition to capture the metal ions.

[0012] However, chelating agents such as EDTA are classified as harmful by the GHS and are not decomposed by microorganisms, posing issues from the perspective of environmental conservation. Furthermore, chelating agents synthesized from petroleum-derived materials present challenges in terms of environmental adaptability, such as reducing carbon dioxide emissions. Additionally, IDS is known as a chelating agent that can be decomposed by microorganisms, but complex formation is difficult in low pH conditions, reducing the functionality of the chelating agent. This also creates the issue of poor storage stability and ejection stability in acidic conditions.

[0013] Therefore, in this embodiment, fulvic acid is used as the chelating agent. Fulvic acid is derived from plants and is non-toxic, making it highly environmentally adaptable. Furthermore, fulvic acid has good water solubility in acidic and basic environments, and its chelating function has low pH dependency, making it possible to trap metal ions in a wide range of pH environments, thereby improving storage stability and ejection stability.

[0014] Components that may be contained in the ink composition according to this embodiment and a production method thereof will be described in detail below.

[0015] 1.1.Colorants The coloring material is not particularly limited, but examples thereof include pigments and dyes. Among these, pigments are preferred. The coloring material may be used alone or in combination of two or more.

[0016] The pigment is not particularly limited, and examples thereof include inorganic pigments such as carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, and titanium oxide; and organic pigments such as quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.

[0017] The pigment may also be a biomass-derived pigment, such as vegetable charcoal obtained by carbonizing plants, such as binchotan charcoal, bamboo charcoal, activated charcoal, white charcoal, black charcoal, briquetted charcoal, sawdust charcoal, plum charcoal, activated charcoal, oak charcoal, Douglas fir charcoal, seaweed charcoal, mangrove charcoal, and coconut shell charcoal; or vegetable oil charcoal (vegetable oil carbon black) obtained by carbonizing vegetable oil.

[0018] In particular, the carbon black may include petroleum-derived carbon black, biomass-derived carbon black, and recycled carbon black. Among these, biomass-derived carbon black is preferred from the viewpoints of reducing petroleum-derived components, reducing carbon dioxide emissions due to petroleum-derived components, and enhancing environmental adaptability.

[0019] Among these, biomass-derived and recycled pigments are preferred, with biomass-derived pigments being more preferred. Biomass-derived and recycled pigments tend to contain impurity metal ions due to the raw materials. Therefore, the metal ions can easily be chelating with fulvic acid. Furthermore, when carbon black is used as a colorant, the pH of the ink composition tends to decrease and become acidic over long-term storage due to the influence of impurities. This tendency is particularly pronounced with carbon black biomass-derived and recycled pigments. Therefore, chelating with fulvic acid, whose chelating function has low pH dependency, is preferred. Furthermore, biomass-derived and recycled pigments tend to contain a large amount of impurities, have a large average particle size, and a wide particle size distribution, and therefore are prone to impairing storage stability due to metal ions. From this perspective, it is also preferable to improve storage stability and ejection stability with fulvic acid.

[0020] In this specification, "biomass-derived" refers to a material produced from a living organism, such as a plant, animal, or microorganism, rather than a material derived from a fossil fuel, such as petroleum or coal. "Recycle-derived" refers to a material produced from recycled materials, such as carbon black obtained by pyrolysis of waste materials, such as scrap tires.

[0021] The pigment may be a self-dispersing pigment that can be dispersed in an aqueous medium without a dispersant, or a resin-dispersed pigment that is dispersed in a resin. Of these, resin-dispersed pigments are preferred.

[0022] A self-dispersing pigment is a pigment that can be dispersed in an aqueous medium without a dispersant. Examples of such self-dispersing pigments include pigments that have been subjected to physical or chemical surface treatment to directly introduce hydrophilic functional groups onto the pigment surface and then dispersed in a solvent.

[0023] The resin-dispersed pigment is a pigment dispersed in a resin. The resin-dispersed pigment may be one that has undergone a process of dispersing a colorant with a resin dispersant, or one that has undergone a process of surface-coating and encapsulating a colorant with a resin.

[0024] The content of the colorant relative to the total amount of the ink composition is preferably 0.1 to 20 mass%, 1 to 15 mass%, 3 to 10 mass%, or 5 to 8 mass%. When the content of the colorant is within the above range, storage stability and ejection stability tend to be further improved.

[0025] 1.2.Dispersants The dispersant is not particularly limited, and examples thereof include lignin sulfonates; (meth)acrylic resins such as poly(meth)acrylic acid, (meth)acrylic acid-acrylonitrile copolymer, (meth)acrylic acid-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid copolymer, and vinylnaphthalene-(meth)acrylic acid copolymer; styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, styrene-α-methylstyrene-(meth)acrylic acid copolymer, and styrene-α-methylstyrene-(meth)acrylic acid copolymer. Examples of suitable water-soluble resins include acrylic acid-(meth)acrylic acid ester copolymers and their salts; maleic acid resins such as styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, and their salts; urethane resins and their salts, which are polymeric compounds containing urethane bonds formed by the reaction of an isocyanate group with a hydroxyl group and may be linear and / or branched, and may have a crosslinked structure; polyvinyl alcohols; vinyl naphthalene-maleic acid copolymers and their salts; vinyl acetate-maleic acid ester copolymers and their salts; and vinyl acetate-crotonic acid copolymers and their salts. Among these, preferred are copolymers of a monomer having a hydrophobic functional group and a monomer having a hydrophilic functional group, and polymers composed of a monomer having both a hydrophobic and a hydrophilic functional group. The copolymers may be random copolymers, block copolymers, alternating copolymers, or graft copolymers.

[0026] Among these, lignin sulfonate and acrylic resin dispersants are preferred. The acrylic resin is a resin using at least an acrylic monomer as described above. It may also be an acrylic resin using an acrylic monomer and a monomer other than the acrylic monomer. Among acrylic resins, acrylic-vinyl resins are preferred. Use of such a dispersant tends to further improve storage stability and ejection stability.

[0027] Commercially available lignin sulfonates include, for example, Pearlex NP (manufactured by Nippon Paper Industries Co., Ltd.), Pearlex DP (manufactured by Nippon Paper Industries Co., Ltd.), Vanilex N (manufactured by Nippon Paper Industries Co., Ltd.), 471038-100G (manufactured by Sigma-Aldrich), New Calgen WG-4 (manufactured by Takemoto Oil & Fat Co., Ltd.), and Sunex P252 (manufactured by Nippon Paper Industries Co., Ltd.).

[0028] Commercially available acrylic resin dispersants include, for example, X-200, X-1, X-205, Examples include X-220 and X-228 (manufactured by Seiko PMC), Nopcosperse (registered trademark) 6100 and 6110 (manufactured by San Nopco Ltd.), Joncryl 67, 586, 611, 678, 680, 682 and 819 (manufactured by BASF), DISPERBYK-190 (manufactured by BYK Japan KK), N-EA137, N-EA157, N-EA167, N-EA177, N-EA197D, N-EA207D and E-EN10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0029] The content of the dispersant is preferably 1.0 to 15 mass%, more preferably 2.0 to 12 mass%, or even more preferably 3.0 to 9.0 mass%, relative to the total amount of the ink composition. When the content of the dispersant is within the above range, storage stability and ejection stability tend to be further improved.

[0030] Fulvic Acid The ink composition contains fulvic acid. The fulvic acid may be in the form of a fulvic acid salt. The fulvic acid functions as a chelating agent and captures metal ions, which tends to further improve storage stability and ejection stability.

[0031] Fulvic acid is a general term for a group of acidic substances contained in corrosive materials that do not precipitate with acid. It can be obtained by separating and purifying soil using acid and alkali, and is also available commercially. It is also produced during oxidation processes such as self-dispersion of carbon black. The fulvic acid obtained in this way is highly water-soluble and has low pH dependency, so it can maintain its water solubility over a wide pH range and is less likely to become contaminated even when the pH changes. In other words, it can function effectively as a chelating agent even when changes occur in the state of the ink composition. This also contributes to its excellent storage stability.

[0032] In this embodiment, the composition may be prepared by mixing separately prepared fulvic acid, or the fulvic acid separated from the treatment liquid generated as a by-product during the oxidation treatment of biomass-derived carbon black may be concentrated or diluted and used.

[0033] In excitation fluorescence matrix analysis, fulvic acid preferably has a peak at a fluorescence wavelength (EM) of 380 to 600 nm and an excitation wavelength (EX) of 180 to 320 nm, and more preferably has a peak at a fluorescence wavelength (EM) of 400 to 600 nm and an excitation wavelength (EX) of 200 to 300 nm. In other words, fulvic acid preferably has a peak in the above-mentioned excitation wavelength (EX) range corresponding to the above-mentioned fluorescence wavelength (EM) range.

[0034] The fulvic acid produced during the oxidation treatment of carbon black may have peaks of fluorescence wavelength and excitation wavelength within the above ranges. Such fulvic acid has a carbon skeleton similar to that of carbon black, has high affinity with carbon black, and is likely to exhibit dispersion stabilizing effects, which tends to further improve storage stability.

[0035] The peak position of the fluorescence wavelength of the fulvic acid of this embodiment in excitation fluorescence matrix analysis is preferably 400 to 550 nm, 400 to 500 nm, 420 to 480 nm, or 430 to 460 nm. When the fluorescence wavelength of the fulvic acid is within the above range, storage stability tends to be further improved.

[0036] The peak position of the excitation wavelength of the fulvic acid of this embodiment in excitation fluorescence matrix analysis is preferably 200 to 320 nm, 200 to 300 nm, 220 to 280 nm, or 240 to 270 nm. When the excitation wavelength of the fulvic acid is within the above range, storage stability tends to be further improved.

[0037] In the excitation-emission matrix analysis, the number of peaks of the fluorescence wavelength and excitation wavelength of fulvic acid within the above ranges may be one or more, for example, 1 to 5. It may also be 2 to 3. When fulvic acid has multiple peaks, it is preferable that at least one peak falls within the above wavelength range. It is more preferable that all peaks fall within the above wavelength range. In other words, it is more preferable that there are no peaks that do not fall within the above wavelength range.

[0038] The content B of fulvic acid is preferably 0.005 to 5.0 mass%, 0.001 to 4.0 mass%, 0.03 to 3.0 mass%, 0.05 to 2.0 mass%, or 0.10 to 1.0 mass% relative to the total amount of the ink composition. When the content B of fulvic acid is within the above range, storage stability tends to be further improved.

[0039] The mass ratio (B / A) of the fulvic acid content B to the coloring material content A is preferably 0.0001 to 0.5, 0.001 to 0.4, 0.005 to 0.3, or 0.01 to 0.2. When the mass ratio of the fulvic acid content B to the coloring material content A is within the above range, storage stability tends to be further improved.

[0040] Metal Ions The lower the content of metal ions in the ink composition, the more suppressed is the deterioration of storage stability and ejection stability due to the metal ions. From this perspective, the total content of metal ions of one or more elements selected from the group consisting of Ca, Mg, Al, Fe, Si, Zn, Cu, and Sn is preferably 140 ppm or less, 120 ppm or less, 100 ppm or less, or 80 ppm or less, relative to the total amount of the ink composition. In particular, the total content of divalent or higher metal ions is preferably 140 ppm or less, 120 ppm or less, 100 ppm or less, or 80 ppm or less, relative to the total amount of the ink composition. Furthermore, the total content of metal ions of one or more elements selected from the group consisting of Ca, Mg, Al, Fe, Si, Zn, Cu, and Sn is 0 ppm or more, preferably 1 ppm or more, 5 ppm or more, 10 ppm or more, or 15 ppm or more, relative to the total amount of the ink composition. Furthermore, it may be 30 ppm or more, or 50 ppm or more.

[0041] When the content of the metal ions is 140 ppm or less, the storage stability and ejection stability tend to be further improved by the action of fulvic acid. Also, when the content of the metal ions is 1 ppm or more, there is no need to purify the ink composition or raw materials excessively, making it easier to produce the ink composition. In addition, even if a certain amount of metal ions is contained, the fulvic acid tends to exhibit the effect of improving the storage stability and ejection stability.

[0042] 1.5. Organic Solvents The ink composition may contain an organic solvent. Examples of the organic solvent include polyols and glycol ethers. Examples of the polyols include diethylene glycol, 1,2-hexanediol, propylene glycol, and glycerin. The glycol ether may be a monoether or diether of an alkylene glycol, such as ethylene glycol monomethyl ether or triethylene glycol monobutyl ether. One type of organic solvent may be used alone, or two or more types may be used in combination.

[0043] The content of the organic solvent is preferably 1% by mass or more relative to the total amount of the ink composition, and more preferably 5 to 35% by mass, 10 to 30% by mass, or 15 to 25% by mass. When the content of the organic solvent is within the above range, storage stability and ejection stability tend to be further improved.

[0044] 1.6.Surfactants The ink composition may contain a surfactant. Examples of the surfactant include silicone surfactants, acetylene glycol surfactants, and fluorine surfactants. The surfactants may be used alone or in combination of two or more.

[0045] The acetylene glycol surfactant is not particularly limited, but is preferably at least one selected from the group consisting of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and 2,4-dimethyl-5-decyne-4-ol and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol. Commercially available acetylene glycol surfactants are not particularly limited, but examples include the E series (trade names: Olfin 104 series, Olfin E1010, etc., manufactured by Air Products Co., Ltd.), and Surfynol 61, 104, and 465 (trade names, manufactured by Nissin Chemical Industry Co., Ltd.). Among these, it is preferable to include Olfin E1010 as a surface tension modifier, from the viewpoint of more effectively and reliably achieving the effects of the present invention.

[0046] The content of the surfactant is preferably 0.01 to 1.5 mass%, 0.05 to 1 mass%, or 0.07 to 0.8 mass%, relative to the total amount of the ink composition. When the content of the surfactant is within the above range, storage stability and ejection stability tend to be further improved.

[0047] 1.7. pH adjusters The ink composition may contain a pH adjuster as needed. Examples of pH adjusters include inorganic acids (e.g., sulfuric acid, hydrochloric acid, nitric acid, etc.), inorganic bases (e.g., lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, etc.), organic acids (e.g., adipic acid, citric acid, succinic acid, etc.), and organic bases (triethanolamine, diethanolamine, monoethanolamine, triisopropanolamine, diisopropanolamine, trishydroxymethylaminomethane). One pH adjuster may be used alone, or two or more may be used in combination.

[0048] The content of the pH adjuster relative to the total amount of the ink composition is preferably 0.1 to 2.0 mass%, 0.3 to 1.5 mass%, or 0.5 to 1.2 mass%. When the content of the pH adjuster is within the above range, the chelating effect of fulvic acid is enhanced, and storage stability and ejection stability tend to be further improved.

[0049] 1.8.Water The water content is preferably 50 to 95 mass %, 55 to 90 mass %, or 60 to 85 mass % relative to the total amount of the ink composition. When the water content is within the above range, the storage stability and ejection stability tend to be excellent.

[0050] 1.9.Other Ingredients The ink composition may contain components other than those described above, such as a dissolution aid, a viscosity adjuster, an antioxidant, a preservative, an antifungal agent, a corrosion inhibitor, and various other additives.

[0051] 1.10.pH The pH of the ink composition of this embodiment after storage at 40°C for two months is preferably 8 or less, 7 or less, less than 7, 6.7 or less, or 6.5 or less. The lower limit of the pH is preferably 4 or more, 5 or more, or 6 or more. Storage conditions such as storage at 40°C for two months are fully expected as storage conditions for ordinary ink compositions, but even under the above-mentioned acidic conditions, the fulvic acid in the ink composition of this embodiment effectively functions as a chelating agent, and therefore the ink composition has excellent storage stability and ejection stability. The pH of the ink composition of this embodiment after storage at 60° C. for one day is preferably 7 to 10.0, 7.5 to 9.0, or 8.0 to 8.5.

[0052] 2. Recording method The recording method according to this embodiment includes a step of ejecting the inkjet ink composition from an inkjet head and depositing it on a recording medium. The recording method according to this embodiment may further include a step of transporting the recording medium, and the step of depositing and the step of transporting may be performed simultaneously.

[0053] 3. Recording device The recording apparatus according to this embodiment is a recording apparatus that performs recording using the ink composition described above. The recording apparatus may also be an inkjet recording apparatus that performs recording by an inkjet method, and is preferable.

[0054] The inkjet recording apparatus of the present embodiment includes the ink composition described above and an inkjet head having a nozzle that ejects the ink composition onto a recording medium, and preferably further includes a supply flow path that distributes the ink composition and is connected to the inkjet head, and a filter unit provided in the supply flow path of the inkjet head.

[0055] An example of an inkjet recording apparatus that can be used in this embodiment is shown in Figure 4. The inkjet recording apparatus according to this embodiment will be described in further detail with reference to Figure 4. In the XYZ coordinate system shown in Figure 4, the X direction indicates the length direction of the recording medium, the Y direction indicates the width direction of the recording medium on the transport path within the recording apparatus, and the Z direction indicates the height direction of the apparatus.

[0056] As an example, the recording device 10 is a line-type inkjet printer capable of high-speed, high-density printing. The recording device 10 includes a feed unit 12 that stores recording media P such as paper, a conveyance unit 14, a belt conveyance unit 16, a recording unit 8, an Fd (face-down) discharge unit 20 as an "discharge unit," an Fd (face-down) placement unit 22 as a "placement unit," a reversing path unit 24 as a "reversing conveyance mechanism," an Fu (face-up) discharge unit 26, and an Fu (face-up) placement unit 28.

[0057] The feeding unit 12 is disposed at the bottom of the recording device 10. The feeding unit 12 includes a feeding tray 30 that stores recording media P, and a feeding roller 32 that sends the recording media P stored in the feeding tray 30 to the transport path 11.

[0058] The recording medium P stored in the feed tray 30 is fed by a feed roller 32 along the conveying path 11 to the conveying unit 14. The conveying unit 14 includes a conveying drive roller 34 and a conveying driven roller 36. The conveying drive roller 34 is driven to rotate by a drive source (not shown). In the conveying unit 14, the recording medium P is nipped between the conveying drive roller 34 and the conveying driven roller 36 and conveyed to the belt conveying unit 16 located downstream of the conveying path 11.

[0059] The belt conveying section 16 includes a first roller 38 located upstream on the conveying path 11, a second roller 40 located downstream, an endless belt 42 rotatably attached to the first roller 38 and the second roller 40, and a support 44 that supports the upper section 42a of the endless belt 42 between the first roller 38 and the second roller 40.

[0060] The endless belt 42 is driven by the first roller 38 or the second roller 40, which is driven by a drive source (not shown), so as to move from the +X direction to the −X direction in the upper section 42a. Therefore, the recording medium P conveyed from the conveying unit 14 is further conveyed downstream of the conveying path 11 in the belt conveying unit 16.

[0061] The recording unit 8 includes a line-type inkjet head 48 and a head holder 46 that holds the inkjet head 48. The recording unit 8 may also be a serial type in which the inkjet head is mounted on a carriage that moves back and forth in the Y-axis direction. The inkjet head 48 is disposed so as to face the upper section 42a of the endless belt 42 supported by the support 44. When the recording medium P is transported in the upper section 42a of the endless belt 42, the inkjet head 48 ejects an ink composition toward the recording medium P to perform recording. The recording medium P is transported downstream of the transport path 11 by the belt transport unit 16 while recording is being performed.

[0062] A first branching section 50 is provided downstream of the conveying path 11 of the belt conveying unit 16. The first branching section 50 is configured to be switchable between the conveying path 11 that conveys the recording medium P to the Fd discharge unit 20 or the Fu discharge unit 26 and a reversing path 52 of the reversing path unit 24 that reverses the recorded side of the recording medium P and conveys the recording medium P again to the recording unit 8. The recording medium P that is switched to the reversing path 52 by the first branching section 50 and conveyed has its recorded side reversed during the conveying process on the reversing path 52, and is conveyed again to the recording unit 8 so that the side opposite to the initially recorded side faces the inkjet head 48.

[0063] A second branch section 54 is further provided downstream of the first branch section 50 along the conveying path 11. The second branch section 54 is configured to be able to switch the conveying direction of the recording medium P so that the recording medium P is conveyed toward the Fd discharge section 20 or the recording medium P is conveyed toward the Fu discharge section 26.

[0064] The recording medium P transported from the second branching section 54 toward the Fd discharge section 20 is discharged from the Fd discharge section 20 and placed on the Fd placement section 22. At this time, the recording medium P is placed so that the recorded surface faces the Fd placement section 22. Also, the recording medium P transported from the second branching section 54 toward the Fu discharge section 26 is discharged from the Fu discharge section 26 and placed on the Fu placement section 28. At this time, the recording medium P is placed so that the recorded surface faces away from the Fu placement section 28.

[0065] 4. Recording Media The recording medium used in this embodiment is not particularly limited, and examples thereof include absorbent recording media, low absorbent recording media, and non-absorbent recording media, with absorbent recording media being preferred.

[0066] Examples of absorbent recording media include plain paper such as electrophotographic paper that has high ink composition permeability, inkjet paper (paper specifically for inkjet printing that has an ink composition absorbing layer made of silica particles or alumina particles, or an ink composition absorbing layer made of a hydrophilic polymer such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP)), cardboard, and fabrics such as cotton, silk, and blends.

[0067] Examples of low-absorbency recording media include art paper, coated paper, cast paper, and the like, which are used in general offset printing and have relatively low ink composition permeability.

[0068] Examples of non-absorbent recording media include films and plates of plastics such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, polyurethane, etc.; plates of metals such as iron, silver, copper, aluminum, etc.; metal plates and plastic films made by vapor deposition of these various metals, and alloy plates such as stainless steel and brass; and recording media in which a plastic film such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, polyurethane, etc. is adhered (coated) to a paper substrate.

[0069] 5. Recordings The recorded matter of this embodiment is obtained by applying the ink composition described above to a recording medium. The recorded matter of this embodiment using the ink composition described above can be recorded with an ink composition that has excellent storage stability and ejection stability. Furthermore, by using an ink composition that contains carbon black derived from biomass or carbon black derived from recycled raw materials, it is possible to record with an ink composition that has excellent storage stability and ejection stability while being environmentally friendly. [Example]

[0070] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0071] In FIG. 1, Table 1 shows the composition of each ink composition of the examples and comparative examples and the evaluation results thereof.

[0072] 1. Preparation of Ink Composition A pigment dispersion is prepared by mixing a pigment and a dispersant in the mass ratios shown in Tables 1 and 2 and stirring in water. The resulting pigment dispersion is then mixed with the remaining components to obtain an ink composition. The numerical values ​​for each component shown in each example in the tables represent mass % unless otherwise specified. Furthermore, each numerical value in the tables represents the mass % of the solid content of the component.

[0073] Furthermore, in order to objectively assess the situation when metals are present in the ink composition, the ink composition is evaluated with the addition of metal precursors. Specifically, the following metal precursors are added to each ink to achieve the compositions shown in Tables 1 and 2. At this time, since the plant-derived CB contains metals derived from the pigment, the amount of metal ions in the state including the metals derived from the pigment is adjusted to the values ​​shown in Tables 1 and 2. Furthermore, if necessary, the pigment is also purified so that the amount of metal ions is the value shown in Tables 1 and 2.

[0074] Details of the product ingredients used in Tables 1 and 2 are as follows: [Colorant] Petroleum-derived CB (Aqua-Black 162, manufactured by Tokai Carbon Co., Ltd.) Binchotan charcoal (manufactured by Kiriya Chemical Co., Ltd.) Plant-derived CB (vegetable oil-based, manufactured by Orion Engineered Carbons) [Dispersant] Joncryl 678 (styrene acrylic resin, manufactured by BASF) Pearlex NP (sodium lignosulfonate, manufactured by Nippon Paper Industries Co., Ltd.) [Chelating agent] Fulvic acid (see example 1 below) IDS (Iminodisuccinic acid tetrasodium) EDTA (Ethylenediaminetetraacetic acid disodium dihydrate) [Organic solvents] 12HD (1,2-hexanediol) PG (propylene glycol) [Surfactants] E1010 (Olfine E1010, manufactured by Nissin Chemical Industry Co., Ltd.) [pH adjuster] TEA (triethanolamine) [Metal Raw Materials] Ca source: calcium carbonate solution Zn source: Zinc stearate solution Mg source: magnesium stearate solution Fe source: iron carbonate solution Al source: aluminum hydroxide Cu source: copper hydroxide solution Sn source: tin hydroxide solution Si source: 0.1% silica solution (NaOH solution)

[0075] 1.1. Preparation Example 1 (Fulvic Acid Preparation Example) 25g of carbon black (PRINTEX Nature, vegetable oil carbon black manufactured by Orion Engineered Carbons Co., Ltd.) was stirred and washed with toluene to wash away unburned matter and other substances adhering to the carbon black surface. After the washing process, 5g of sodium hypochlorite was added to the carbon black in water for oxidation treatment. After treatment, the carbon black was removed by centrifugation, the waste liquid was recovered, and an alkaline aqueous solution was added to the waste liquid to separate the resulting insoluble matter (humus) from the liquid. An acid aqueous solution was then added to the liquid remaining after the insoluble matter had been removed, separating the resulting insoluble matter, and the remaining liquid was concentrated and purified to obtain fulvic acid.

[0076] 1.2.Excitation Emission Matrix Analysis (EEM) The carbon black dispersion prepared as described above is centrifuged (Suprema 21 high-speed refrigerated centrifuge, manufactured by Tomy Seiko Co., Ltd.) at 20°C, 12,000 rpm, and 120 min to allow the carbon black to settle. If fine particles remain in the supernatant, 0.1% to 0.5% magnesium sulfate is added to the carbon black to cause coagulation, and the carbon black is then precipitated again in the centrifuge. The carbon black is then removed, and the supernatant is used as the measurement sample.

[0077] The obtained measurement sample is diluted 1000 times with pure water, and the excitation wavelength (Ex) is measured three-dimensionally using the side reflection method under the following conditions. Note that if the prepared measurement specimen is thick, the surface reflection method can also be selected. Holder: Liquid holder (side photometry system) or solid holder (surface photometry system) Cell: Polished quartz cell (10 x 10 mm square quartz cell, side photometry) or double-polished quartz cell (20 x 10 mm quartz cell, surface photometry) Measurement wavelength Excitation (Ex): 200-700 nm Measurement wavelength: Fluorescence (Em): 200-700nm Data interval Excitation (Ex): 5.0 nm Data interval Fluorescence (Em): 5.0 nm Scan speed: 60,000nm / min Slit width Excitation (Ex): 5.0 nm Slit width Fluorescence (Em): 5.0 nm Sensitivity: Photomultiplier voltage 700V Response time: 2ms Automatic filter control: ON (automatic high-order light cut)

[0078] The measurement results of the excitation-emission matrix analysis showed that the fulvic acid obtained by the above Preparation Example 1 has two peaks: one at an excitation wavelength of 260 nm and a fluorescence wavelength of 445 nm, and the other at an excitation wavelength of 265 nm and a fluorescence wavelength of 430 nm.

[0079] 1.3.Mass analysis of metal components Mass spectrometry of each metal component in the ink composition was measured using an ICP-OES (G8015AA, manufactured by Agilent Technologies, Inc.).

[0080] 1.4.pH The prepared ink composition is stored at 60°C for one day, and then the pH is measured using a glass electrode pH meter (manufactured by Yokogawa Corporation, product name Model PH82). Note that there is no significant change in pH from the pH measured immediately after production, and the pH is either unchanged or less than 1.

[0081] 2. Evaluation Method 2.1.Storage stability (60℃, 1 day) The ink composition is placed in a polyethylene bag and left to stand at 60°C for one day, and then allowed to cool at 25°C for one day. After cooling, the ink composition is removed and passed through a 10 μm diameter filter. The residue collected on the filter is checked and the storage stability is evaluated according to the following evaluation criteria. The ink composition is then visually observed under a microscope at 300x magnification. (Evaluation criteria) A: The number of foreign objects is less than 10 B: The number of foreign objects is 10 or more but less than 50 C: 50 or more foreign objects

[0082] 2.2. Discharge stability (60℃, 1 day) The ink composition stored at 60°C for 1 day is filled into a predetermined ink composition container, the container is attached to a recording device (a modified PX-H6000 manufactured by Seiko Epson Corporation), the inkjet ink composition is ejected, a solid pattern is printed on a recording medium (Xerox P paper) at a recording resolution of 1440 x 720 dpi, the ejection state after printing is confirmed, and the ejection stability is evaluated according to the following evaluation criteria. The operating environment of the recording device (printer) is 40°C and 20% RH. (Evaluation criteria) A: The number of non-ejecting nozzles is 3% or less B: The number of non-ejecting nozzles is over 3% and 7% or less C: Number of non-ejecting nozzles exceeds 7%

[0083] 2.3. Storage stability (40°C, after 2 months storage) The storage stability of Example 9, Comparative Examples 2 and 3, and Reference Example 1 is evaluated in the same manner as above, except that the storage conditions are set to 40°C for 2 months. The pH of the ink composition at this time (after leaving it at 40°C for 2 months) is also measured using a glass electrode pH meter. (Evaluation criteria) A: The number of foreign objects is less than 10 B: The number of foreign objects is 10 or more but less than 50 C: 50 or more foreign objects

[0084] 2.4. Discharge stability (after leaving at 40°C for 2 months) The ejection stability of Example 9, Comparative Examples 2 and 3, and Reference Example 1 is evaluated in the same manner as in the evaluation of ejection stability, except that the ink stored at 40° C. for 2 months is used. (Evaluation criteria) A: The number of non-ejecting nozzles is 3% or less B: The number of non-ejecting nozzles is over 3% and 7% or less C: Number of non-ejecting nozzles exceeds 7%

[0085] 2.5.GHS classification The components contained in the inks of Example 9, Comparative Examples 2 and 3, and Reference Example 1 are evaluated to see whether they fall under Category 3 of the aquatic environment hazard classification in the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). (Evaluation criteria) Y: Not applicable N: Applicable

[0086] 3. Evaluation Results Tables 1 and 2 show the evaluation results of the ink compositions used in each example. Table 1 shows that the water-based inkjet ink composition containing a colorant and fulvic acid has excellent storage stability and ejection stability. Furthermore, as shown in Table 3, the water-based inkjet ink composition of the present invention has high environmental adaptability and exhibits excellent storage stability and ejection stability even when stored for a long period of time. [Explanation of symbols]

[0087] 10...recording device, 11...transport path, 12...feed section, 14...transport section, 16...belt transport section, 18...recording section, 20...Fd discharge section, 22...Fd placement section, 24...reversal path section, 26...Fu discharge section, 28...Fu placement section, 30...feed tray, 32...feed roller, 34...transport drive roller, 36...transport driven roller, 38...first roller, 40...second roller, 42...endless belt, 42a...upper section of endless belt, 44...support, 46...head holder, 48...inkjet head, 50...first branch section, 52...reversal path, 54...second branch section, 56...discharge roller pair, 64...discharge drive roller, 68...drive shaft, 76...placement surface, 78...convex section, 80...first urging member, 82...second urging member, 84, 86...support shaft, P...recording medium.

Claims

1. Color material and Fulvic acid and contains Aqueous ink-jet ink compositions.

2. the content of the fulvic acid is 0.001 to 1.0% by mass relative to the total amount of the inkjet ink composition; The water-based ink-jet ink composition of claim 1 .

3. The fulvic acid has a peak at a fluorescence wavelength of 400 nm to 600 nm and an excitation wavelength (EX) of 200 nm to 300 nm in an excitation fluorescence matrix analysis method. The water-based ink-jet ink composition of claim 1 .

4. the total content of metal ions of one or more elements selected from the group consisting of Ca, Mg, Al, Fe, Si, Zn, Cu, and Sn is 140 ppm or less relative to the total amount of the inkjet ink composition; The water-based ink-jet ink composition of claim 1 .

5. pH is less than 7 after storage at 40°C for 2 months; The water-based ink-jet ink composition of claim 1 .

6. The coloring material includes a pigment. The water-based ink-jet ink composition of claim 1 .

7. The colorant contains petroleum-derived carbon black or biomass-derived carbon black. The water-based ink-jet ink composition of claim 1 .

8. The colorant contains a pigment dispersed in a resin. The water-based ink-jet ink composition of claim 1 .

9. a deposition step of ejecting the water-based inkjet ink composition according to any one of claims 1 to 8 from an inkjet head and depositing it on a recording medium; Recording method.

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