Carbon black composition, ink composition, recording method, and recorded matter

Abstract

To provide a carbon black composition excellent in storage stability.SOLUTION: The carbon black composition for coloring contains carbon black and fulvic acid, wherein the carbon black contains a hydrophilic functional group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a carbon black composition, an ink composition, a recording method, and a recorded matter. [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 inks have been developed by using materials derived from natural products. For example, Patent Document 1 discloses an inkjet ink composition containing water, a plant-derived carbonized colorant, and a lignin resin, with the aim of providing an ink composition that has excellent color development properties while also exhibiting excellent ejection reliability, such as redispersibility and clogging recovery properties. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-167623 Summary of the Invention [Problem to be solved by the invention]

[0004] Regarding carbon black used as a coloring material, there is still room for improvement in the storage stability of carbon black. [Means for solving the problem]

[0005] The carbon black composition for coloring of the present invention contains carbon black and fulvic acid, and the carbon black has a hydrophilic functional group.

[0006] The ink composition of the present invention contains the above-described carbon black composition. The recording method of the present invention comprises a step of depositing the ink onto 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 compositions used in the examples and the evaluation results thereof. [Figure 2] Table 2 shows the compositions used in the examples and the evaluation results thereof. [Figure 3] 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. Carbon black composition The carbon black composition for coloring according to this embodiment contains carbon black and fulvic acid, and the carbon black has a hydrophilic functional group.

[0011] Carbon black itself does not have excellent storage stability, and aggregation occurs over time, resulting in an increase in particle size or an increase in viscosity. Therefore, there is still room for improvement in the storage stability of carbon black. In recent years, environmentally friendly carbon black, such as carbon black derived from biomass or recycled materials, has been attracting attention. However, there is still room for improvement, particularly in terms of the storage stability of such carbon black.

[0012] Therefore, in this embodiment, a carbon black composition for coloring that has excellent storage stability is provided by using carbon black having a hydrophilic functional group and fulvic acid.

[0013] In this embodiment, the hydrophilic functional groups of carbon black contribute to improving affinity with fulvic acid, promoting adhesion and adsorption of fulvic acid to the carbon black surface. Meanwhile, fulvic acid can function as a dispersing agent for carbon black on the carbon black surface. More specifically, fulvic acid functions like a surface coating near the carbon black surface, which is thought to prevent further aggregation and coarsening of primary and secondary particles of carbon black. Furthermore, it is thought that this can also prevent impurities from adhering to the carbon black. Furthermore, the carbon black composition also has excellent storage stability for inks prepared using the composition, excellent color development of images recorded with the ink, and excellent ejection stability when used as an inkjet ink. However, the effect of fulvic acid on improving storage stability is not limited to the above.

[0014] The carbon black composition of this embodiment may be, for example, a dispersion in which carbon black is dispersed in a dispersion medium, or may be a powdery composition or a paste-like composition. When it is a dispersion, it can be used, for example, to prepare inks and the like.

[0015] The carbon black composition may be used as a raw material for imparting coloring properties to compositions such as inks, paints, and toners, or may be mixed with plastic materials and used as a colorant to color the plastic materials themselves. This composition is used to impart a color such as black to these materials. In other words, carbon black is a pigment that functions as a colorant.

[0016] Components that may be contained in the carbon black composition according to this embodiment and a production method thereof will be described in detail below.

[0017] 1.1.Carbon black In this embodiment, carbon black having a hydrophilic functional group is used. The hydrophilic functional group of carbon black improves affinity with fulvic acid, making it easier for fulvic acid to be adsorbed onto the surface of the carbon black. The carbon black is not particularly limited, but examples thereof include petroleum-derived carbon black, biomass-derived carbon black, and recycled carbon black.

[0018] Examples of petroleum-derived carbon black include furnace black, lamp black, acetylene black, and channel black (CI Pigment Black 7).

[0019] The biomass-derived carbon black is not particularly limited, and examples thereof include plant charcoal obtained by carbonizing plants, such as binchotan charcoal, bamboo charcoal, activated charcoal, white charcoal, black charcoal, shaped charcoal, sawdust charcoal, plum charcoal, activated charcoal, oak charcoal, Douglas fir charcoal, seaweed charcoal, mangrove charcoal, and coconut shell charcoal. Vegetable oil carbon black, which is made by carbonizing vegetable oil, can also be used. Examples of vegetable oil carbon black include carbon black obtained by incomplete combustion or thermal decomposition of vegetable oil at high temperatures, and carbon black obtained by burning vegetable oil and collecting the smoke produced (lamp black made from vegetable oil).

[0020] Lamp soot and pine soot, which are used in ink, can also be used. Among these, carbon black obtained from inedible plants is preferably used. Carbon black may have a structure such as a crystalline structure, an amorphous structure, or a graphite structure.

[0021] Among these, biomass-derived carbon black and recycled carbon black are preferred from the viewpoint of reducing environmental impact. However, biomass-derived carbon black and recycled carbon black in particular tend to contain complex impurities and have complex structures. Due to these impurities and complex structures, they tend to have relatively poor storage stability.

[0022] Furthermore, some types of biomass-derived carbon black and recycled carbon black tend to contain a high amount of impurities, which can lead to poor storage stability. For this reason, there are concerns that the storage stability of inks containing biomass-derived carbon black, the color development of images recorded with the ink, and the ejection stability when used as an inkjet ink may not necessarily be sufficient. The present invention is particularly useful for such carbon black.

[0023] The term "structure" refers to the size and connectivity of carbon black particles, such as how they are aggregated and what shape and arrangement they take, and refers to, for example, the state of primary particles or secondary particles formed by aggregation of primary particles.

[0024] Examples of hydrophilic functional groups include ionic groups and hydroxyl groups. Examples of ionic groups include acidic groups and basic groups. Examples of such ionic groups include, but are not limited to, carboxyl groups, amino groups, sulfo groups, and phosphorus-containing acid groups. Examples of phosphorus-containing acid groups include phosphate groups and phosphonic acid groups. Acidic groups are preferred. When the hydrophilic functional group is an ionic group, the ionic group may be in the form of a salt or an ionized form, and these are all included in the description.

[0025] Among these, the hydrophilic functional group preferably contains at least one of a hydroxyl group and an acidic group. The acidic group is preferably a carboxyl group. Therefore, the hydrophilic functional group preferably contains at least one of a hydroxyl group and a carboxyl group. When the hydrophilic functional group contains at least one of a hydroxyl group and a carboxyl group, storage stability tends to be further improved.

[0026] Hydrophilic functional groups may be introduced into carbon black by, for example, oxidation treatment or chemical reaction with a compound such as a treating agent, or carbon black having hydrophilic functional groups may be directly obtained and used. For example, hydroxyl groups and carboxyl groups may be introduced into carbon black by oxidation treatment in the presence of an oxidizing agent such as sodium hypochlorite. In this case, the degree of oxidation treatment may be adjusted to control the proportion of hydroxyl groups and carboxyl groups introduced. Furthermore, other ionic groups may be introduced by reacting the hydroxyl groups and carboxyl groups introduced in this manner with a treating agent having an ionic group.

[0027] The DBP oil absorption of the carbon black of this embodiment is preferably 50 to 200 mL / 100 g, 70 to 180 mL / 100 g, 80 to 150 mL / 100 g, or 90 to 130 mL / 100 g. When the DBP oil absorption is within the above range, storage stability tends to be further improved.

[0028] DBP oil absorption is a value expressed as the amount of dibutyl phthalate (DBP) absorbed by 100 g of carbon black, and can be determined according to the measurement method specified in JIS K 6221. Generally, the more developed the structure of carbon black, the greater the DBP oil absorption.

[0029] The average particle size of the primary particles of the carbon black of this embodiment is preferably 10 to 50 nm, 15 to 45 nm, 20 to 40 nm, or 25 to 35 nm. Having the average particle size of the primary particles within the above range tends to further improve storage stability. The primary particle size of the carbon black can be determined as the arithmetic mean diameter by observing the carbon black particles under an electron microscope.

[0030] The DBP oil absorption and average primary particle size of carbon black can be adjusted by adjusting the concentration of the raw material oil and heating conditions such as the heating temperature when producing carbon black.

[0031] The carbon black content A is preferably 0.1 to 25 mass%, 5 to 22 mass%, 10 to 20 mass%, or 12 to 18 mass%, relative to the total amount of the carbon black composition. When the carbon black content A is within the above range, storage stability tends to be further improved.

[0032] The carbon black may be a self-dispersed pigment or a resin-dispersed pigment.

[0033] 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 dispersed in a solvent by directly introducing hydrophilic functional groups onto the pigment surface through physical or chemical surface treatment. The hydrophilic functional groups in the self-dispersing pigment preferably contain an acidic group such as a carboxyl group. Using carbon black as a self-dispersing pigment is preferred because it facilitates adhesion of fulvic acid to the carbon black, further improving storage stability.

[0034] 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 carbon black as the resin with a resin dispersant, or one that has been dispersed through a process of surface-coating and encapsulating carbon black with a resin. If the carbon black that is a resin-dispersed pigment has a hydrophilic functional group, the affinity of the resin to the carbon black is improved, and the resin tends to adhere or adsorb easily, which further improves storage stability, and is therefore preferred.

[0035] Dispersion using a resin dispersant is preferably performed by mixing carbon black and fulvic acid and then dispersing with the resin. Alternatively, carbon black may be dispersed with the resin and then fulvic acid may be mixed. The storage stability of carbon black tends to be improved when fulvic acid adheres to the parts of the carbon black that are not covered with the dispersant. The resin is not particularly limited, and for example, a conventionally known resin can be used.

[0036] 1.1.1.Biomass-derived carbon black The carbon black of the present embodiment preferably includes carbon black derived from biomass. In this specification, the term "biomass-derived raw material" refers to a raw material derived from living organisms such as plants, animals, and microorganisms, rather than a raw material derived from fossil fuels such as petroleum or coal.

[0037] By using biomass-derived carbon black, it is possible to reduce the amount of petroleum-derived components contained in the ink. This allows for a reduction in carbon dioxide emissions compared to when petroleum-derived components are used, resulting in an environmentally friendly ink. Furthermore, biomass-derived carbon black tends to contain many impurities and is prone to generating fulvic acid through oxidation treatment. Raw materials for biomass-derived carbon black include, but are not limited to, vegetable oil and vegetable oil charcoal. Furthermore, storage stability can be an issue due to the large amount of impurities and the complex and large structure, but the present invention is particularly useful because storage stability can be achieved by using fulvic acid.

[0038] Vegetable oil carbon black is made by carbonizing vegetable oil, and its manufacturing process is similar to that of petroleum carbon black in that it is carbonized by burning a liquid, making it relatively easy to manufacture. By refining the liquid raw material, impurities are relatively easily reduced, which prevents impurities from adhering to the carbon black, further improving storage stability.

[0039] 1.1.2. Carbon black made from recycled materials The carbon black of this embodiment preferably contains carbon black derived from recycled materials. By using recycled materials, petroleum-derived components can be reduced, resulting in a lower carbon dioxide emission compared to when petroleum-derived components are used, resulting in an environmentally friendly ink. Carbon black derived from recycled materials is carbon black obtained by pyrolysis of waste materials such as scrap tires. Like biomass-derived carbon black, recycled carbon black tends to contain many impurities and is prone to generating fulvic acid through oxidation treatment. Furthermore, the present invention is particularly useful because storage stability is likely to be an issue due to the large amount of impurities and the complex and large structure.

[0040] 1.2. Fulvic Acid The carbon black composition in this embodiment contains fulvic acid. It is believed that fulvic acid can function as a dispersing aid for carbon black. More specifically, it is believed that fulvic acid functions like a surface coating material near the surface of carbon black, thereby preventing primary and secondary particles of carbon black from further agglomerating and becoming coarser. In addition, it is believed that it can also prevent impurities from adhering to carbon black. However, the effect of fulvic acid in improving storage stability is not limited to the above. It should be noted that in this embodiment, fulvic acid does not fall under the category of the resin dispersant.

[0041] 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 dispersing aid even when changes occur in the state of the ink composition. This also gives it excellent storage stability. In addition, carbon black tends to have excellent properties such as storage stability of inks containing carbon black, color development of images recorded with the ink, and ejection stability when used as an inkjet ink. Fulvic acid may be in the form of a fulvic acid salt.

[0042] 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.

[0043] In excitation-emission 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. In other words, it is preferable that the peak be in the above-mentioned excitation wavelength (EX) range corresponding to the above-mentioned fluorescence wavelength (EM) range. Furthermore, in the excitation fluorescence matrix analysis, it is preferable that the fluorescence has a peak at a fluorescence wavelength (EM) of 400 to 600 nm and an excitation wavelength (EX) of 200 to 300 nm.

[0044] The fulvic acid produced during the oxidation treatment of carbon black has 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 stabilization effects, which tends to further improve storage stability.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The content B of fulvic acid is preferably 0.015 to 15 mass%, 0.03 to 10 mass%, 0.05 to 8 mass%, 0.07 to 6 mass%, or 0.1 to 3 mass%, relative to the total amount of the carbon black composition. When the content B of fulvic acid is within the above range, storage stability tends to be further improved.

[0049] The mass ratio (B / A) of the fulvic acid content B to the carbon black content A is preferably 0.0001 to 0.5, 0.001 to 0.5, 0.005 to 0.3, or 0.01 to 0.1. By setting the mass ratio of the fulvic acid content B to the carbon black content A within the above range, storage stability tends to be further improved.

[0050] 1.3.Organic Solvents The carbon black composition according to this embodiment may contain an organic solvent. Examples of the organic solvent include polyols and glycol ethers. One organic solvent may be used alone, or two or more organic solvents may be used in combination. Examples of the polyol include diethylene glycol, propylene glycol, and glycerin. One organic solvent may be used alone, or two or more organic solvents may be used in combination.

[0051] The content of the organic solvent is preferably 0.1 to 15 mass%, 1 to 10 mass%, 1.5 to 8 mass%, or 2 to 5 mass%, relative to the total amount of the carbon black composition. By setting the content of the organic solvent within the above range, storage stability tends to be further improved.

[0052] 1.4. pH adjuster The carbon black composition may contain a pH adjuster, if necessary. 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 (e.g., triethanolamine, diethanolamine, monoethanolamine, triisopropanolamine, diisopropanolamine, trishydroxymethylaminomethane). One pH adjuster may be used alone, or two or more may be used in combination.

[0053] 1.5.Water The carbon black composition of this embodiment may be a pigment dispersion containing a dispersion medium containing water and carbon black dispersed in the dispersion medium. In other words, the dispersion medium contains at least water as a main component. Because fulvic acid is highly water-soluble, its effect of improving storage stability is particularly pronounced in carbon black dispersions containing a dispersion medium containing water. A pigment dispersion containing at least water as the main component of the dispersion medium is also called an aqueous pigment dispersion.

[0054] The water content, relative to the total amount of the carbon black composition, is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. It is preferably 60 to 95% by mass, 65 to 90% by mass, 70 to 85% by mass, or 75 to 83% by mass. By keeping the water content within the above range, storage stability tends to be further improved.

[0055] 1.6.Other Ingredients The carbon black composition may contain components other than those described above, such as a dissolution aid, a viscosity modifier, an antioxidant, an antiseptic, an antifungal agent, a corrosion inhibitor, and various other additives.

[0056] 2. Ink composition The ink composition of this embodiment contains the carbon black composition described above, and may further contain other components as necessary. The carbon black composition improves storage stability and ejection stability. The ink composition is not particularly limited, but may be an inkjet ink composition. Alternatively, it may be various inks such as inks for analog printing and inks for writing instruments.

[0057] The carbon black content of the ink composition is preferably 0.1 to 20 mass%, 1 to 15 mass%, 3 to 10 mass%, or 5 to 8 mass%, relative to the total amount of the ink composition. A carbon black content within the above range is preferred because it provides better ejection stability, color development, and the like.

[0058] The content of fulvic acid in the ink composition is preferably 0.005 to 5 mass%, 0.01 to 1 mass%, 0.03 to 0.5 mass%, 0.05 to 0.2 mass%, or 0.03 to 0.1 mass% relative to the total amount of the ink composition. A fulvic acid content within the above range is preferred because it provides excellent ejection stability and the like.

[0059] 2.1. Organic Solvents The ink composition of this embodiment may contain an organic solvent. Examples of organic solvents include polyols and glycol ethers. One type of organic solvent may be used alone, or two or more types may be used in combination. Examples of polyols include diethylene glycol, 1,2-hexanediol, propylene glycol, and glycerin. The glycol ether may be a monoether or diether of alkylene glycol, and examples thereof include ethylene glycol monomethyl ether and triethylene glycol monobutyl ether.

[0060] The content of the organic solvent is preferably 1 to 20 mass %, 5 to 18 mass %, 7 to 16 mass %, or 10 to 15 mass % relative to the total amount of the ink composition. By keeping the content of the organic solvent within the above range, storage stability and ejection stability tend to be further improved.

[0061] 2.2.Surfactants The ink composition of this embodiment may contain a surfactant. Examples of surfactants include silicone surfactants, acetylene glycol surfactants, and fluorine surfactants. The surfactants may be used alone or in combination of two or more.

[0062] Commercially available acetylene glycol surfactants are not particularly limited, but examples include E1010, EXP4200, and the like (manufactured by Nissin Chemical Industry Co., Ltd.).

[0063] The content of the surfactant is preferably 0.01 to 1.5 mass%, 0.05 to 1 mass%, 0.07 to 0.8 mass%, or 0.1 to 0.5 mass% relative to the total amount of the ink composition. By keeping the content of the surfactant within the above range, storage stability and ejection stability tend to be further improved.

[0064] 2.3. pH adjuster The ink composition of this embodiment 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.

[0065] 2.4. Chelating Agents The ink composition of this embodiment may contain a chelating agent as needed. When the ink composition contains a chelating agent, storage stability tends to be further improved. The chelating agent is not particularly limited, and examples thereof include ethylenediaminetetraacetate (EDTA), edetate di-salt, pyrophosphate, hexametaphosphate, citric acid, tartaric acid, gluconic acid, and the like. One type of chelating agent may be used alone, or two or more types may be used in combination.

[0066] 2.5.Water The ink composition of this embodiment may contain water as needed, and is preferably an aqueous ink composition containing at least water as a solvent component. The water content is preferably 50% by mass or more, 60 to 98% by mass, 70 to 95% by mass, 75 to 90% by mass, or 77 to 85% by mass relative to the total amount of the ink. When the water content is within the above range, the storage stability and ejection stability tend to be excellent.

[0067] 2.6.Other Ingredients The ink composition may contain components other than those described above. As other components, various additives such as a solubilizing agent, a viscosity modifier, an antioxidant, a preservative, an antifungal agent, and a corrosion inhibitor can be appropriately added.

[0068] The content of each of the above other components is preferably 0 to 10% by mass, 0 to 5% by mass or less, and 0 to 3% by mass, relative to the total amount of the ink composition.

[0069] 3. Recording method The recording method according to this embodiment includes a step of depositing the ink composition onto a recording medium. The recording method may be an inkjet recording method carried out by an inkjet method, and is preferred. The inkjet recording method according to this embodiment includes a step of ejecting the inkjet ink composition from a predetermined inkjet head and depositing the ink onto a recording medium. The inkjet recording method may further include a step of transporting the recording medium, and the depositing step and the transporting step may be performed simultaneously.

[0070] 4. 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. 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.

[0071] An example of an inkjet recording apparatus that can be used in this embodiment is shown in Figure 3. The inkjet recording apparatus according to this embodiment will be described in further detail with reference to Figure 3. In the XYZ coordinate system shown in Figure 3, the X direction indicates the length direction of the recording medium, the Y direction indicates the width direction of the recording medium in the transport path within the recording apparatus, and the Z direction indicates the height direction of the apparatus.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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 that is supported by a support 44. The inkjet head 48 ejects ink toward the recording medium P as the recording medium P is transported in the upper section 42a of the endless belt 42, thereby performing recording. The recording medium P is transported downstream of the transport path 11 by the belt transport unit 16 while recording is being performed.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 5. 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.

[0082] Examples of absorbent recording media include plain paper such as electrophotographic paper, which has high ink permeability, and inkjet paper (paper specifically for inkjet printers, which has an ink absorbing layer made of silica particles or alumina particles, or an ink absorbing layer made of a hydrophilic polymer such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP)).

[0083] 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 permeability.

[0084] 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.

[0085] 6. 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 ink that has excellent storage stability and ejection stability. Furthermore, by using an ink composition containing carbon black derived from biomass or carbon black derived from recycled materials, it is possible to record with ink that has excellent storage stability and ejection stability while being environmentally friendly. [Example]

[0086] 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.

[0087] In FIG. 1, Table 1 shows the composition of each ink composition of Examples and Comparative Examples and the evaluation results thereof.

[0088] 1. Preparation of Carbon Black Composition A dispersion liquid was prepared by mixing and stirring to obtain the composition shown in Table 1, thereby obtaining the carbon black composition of each example. Note that the numerical value of each component shown in each example in the table represents mass % unless otherwise specified. Furthermore, in the table, each numerical value represents mass % of the solid content of the component.

[0089] Details of the product ingredients used in Tables 1 and 2 are as follows: [Carbon black] CB1 to CB6 (see preparation example below) [Fulvic acid] Fulvic acid 1 (see preparation example below) Fulvic Acid 2 (Royal Industries, Royal Fulvic Acid) [Organic solvents] Glycerin (Kanto Chemical Co., Ltd.) [pH adjuster] ·NaOH (sodium hydroxide)

[0090] The carbon book is prepared by processing as follows. The content of each carbon black in Table 1 and Table 2 is the content of the solid content of each carbon black. <Preparation example of CB1> [Washing process] 25 g of carbon black (PRINTEX Nature, manufactured by Orion Engineered Carbons Co., Ltd., vegetable oil carbon black) is stirred and washed with toluene to wash away substances such as unburned components adhering to the surface of the carbon black.

[0091] [Surface treatment process] To the carbon black after the washing process, 5 g of sodium hypochlorite is added in water, and ultrasonic treatment is performed to carry out a surface treatment reaction.

[0092] [Dispersion process] The dispersion of the carbon black after the surface treatment process is subjected to a dispersion treatment for 1 hour with 0.3 mm beads using a rocking mill to obtain a slurry. Then, 20% by mass of sodium hypochlorite is added to the carbon black in the slurry, heated to 70 °C, and a surface treatment reaction is carried out for 30 minutes. If the particle size is measured and the target particle size has not been reached, the above dispersion treatment and surface treatment are carried out again. Since a new hydrophobic surface is generated on the carbon black by dispersion, a surface treatment reaction is also carried out in the dispersion process.

[0093] [Neutralization and purification process] NaOH is added to the dispersion of the carbon black after the dispersion process, and it is neutralized until the pH suitable for the ink becomes 8 to 9. After the neutralization reaction, the dispersion is cooled to room temperature, and solid-liquid separation is carried out using a centrifuge or the like to perform a desalting treatment. Then, the solid matter is recovered and dried at 100 °C. Thereby, CB1, which is carbon black having a carboxyl group introduced onto the surface due to surface treatment, is obtained.

[0094] <Preparation example of CB2> After preparing CB1, carbon black 1 and Hairoth X220 (styrene-maleic acid resin dispersant, Starlight PMC) are mixed in water so that the mass ratio in terms of active ingredients is 4:1, and stirring is carried out with a bead mill to obtain CB2 as a resin-dispersed pigment.

[0095] <Preparation Example of CB3> Except for using Mitsubishi Chemical Corporation's #30 (petroleum-derived carbon black) as the carbon black, CB3 with carboxyl groups introduced onto the surface due to surface treatment is obtained in the same manner as carbon black dispersion liquid 1.

[0096] <Preparation Example of CB4> Except for using Orion Engineered Carbons' Printex30 (petroleum-derived carbon black) as the carbon black, CB4 with carboxyl groups introduced onto the surface due to surface treatment is obtained in the same manner as CB2.

[0097] <Preparation Example of CB5> Except for using Tokai Carbon Co., Ltd.'s TOKA BLACK #4500 (petroleum-derived carbon black) as the carbon black, CB5 with carboxyl groups introduced onto the surface due to surface treatment is obtained in the same manner as CB1.

[0098] <Preparation Example of CB6> Without performing the surface treatment step, and also without performing the surface treatment reaction in the dispersion step, CB6 is obtained in the same manner as CB1. Since no surface treatment step or the like is performed, CB6 is carbon black without carboxyl groups introduced onto the surface.

[0099] <Preparation Example of Full-Bo Acid 1> In the surface treatment process of carbon black 1, the waste liquid after washing is collected, an alkaline aqueous solution is added to the waste liquid to separate the resulting insoluble matter (humus) from the liquid, an acid aqueous solution is further added to the liquid obtained by separation to separate the resulting insoluble matter from the liquid, and the liquid obtained by separation is concentrated and purified to obtain fulvic acid 1. Note that fulvic acid includes fulvic acid in the form of a fulvic acid salt.

[0100] <Preparation example of fulvic acid 2> In the preparation of fulvic acid 1, the aqueous solution of fulvic acid 2 described above is used instead of the waste liquid, and the treatment is carried out in the same manner.

[0101] 1.1.DBP oil absorption 25 g of the carbon black prepared as described above is weighed out and placed in a sample container. The sample container is then heated and maintained at 100°C to remove moisture. The carbon black is then placed in an adsorp meter, and dibutyl phthalate (DBP) is placed in an automatic burette device as oil, and the dropwise addition of dibutyl phthalate begins. The torque curve of the adsorp meter device is recorded using a pen or a data acquisition system, and the value at 70% of the maximum torque is read as the end point. The measurement unit is converted to mL / 100 g, and the average of two measurements is taken as the DBP oil absorption.

[0102] 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.

[0103] 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)

[0104] The measurement results of the excitation-emission matrix analysis showed that fulvic acid 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. In addition, fulvic acid 2 has two peaks: one at an excitation wavelength of 240 nm and a fluorescence wavelength of 540 nm, and the other at an excitation wavelength of 310 nm and a fluorescence wavelength of 440 nm.

[0105] 1.3. Primary particle size of carbon black The carbon black particles are observed under an electron microscope, and the arithmetic mean diameter is calculated to measure the primary particle diameter of the carbon black.

[0106] 2. Preparation of Ink Composition The components were placed in a mixing tank so as to obtain the composition shown in Table 2, mixed and stirred, and then filtered through a membrane filter to obtain the ink composition of each example.

[0107] [Organic solvents] Glycerin (Kanto Chemical Co., Ltd.) BTG (triethylene glycol monobutyl ether, manufactured by Nippon Nyukazai Co., Ltd.) 1,2-HD (1,2-hexanediol, manufactured by Toyo Gosei Co., Ltd.) [pH adjuster] TEA (triethanolamine) [Surfactants] E1010 (acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) [Chelating agent] EDTA (ethylenediaminetetraacetic acid) [water] ·Pure water

[0108] 3. Evaluation Method 3.1.Storage stability (particle size) The dispersion or ink composition is placed in a sealed glass container and left at 60°C for 5 days. After leaving, the dispersion or ink is removed and the average particle diameter D50 (nm) is measured using a dynamic light scattering particle size distribution analyzer (ELSZ-1000, manufactured by Otsuka Electronics). The particle diameters before and after storage are compared to determine the rate of change, and the storage stability is evaluated according to the following evaluation criteria. (Evaluation criteria) A: Change rate less than 10% B: Change rate 10% or more but less than 20% C: Change rate 20% or more but less than 30% D: Change rate 30% or more

[0109] 3.2. Storage stability (viscosity) The dispersion or ink composition is placed in a sealed glass container and left to stand for 5 days at 60°C. After standing, the dispersion or ink is taken out and measured at a shear rate of 200 s using a rheometer (MCR-306, manufactured by Anton Paar). -1 The viscosity is measured under the conditions below. The viscosity is compared before and after storage to determine the rate of change, and the storage stability is evaluated according to the following evaluation criteria. (Evaluation criteria) A: Change rate less than 10% B: Change rate 10% or more but less than 20% C: Change rate 20% or more but less than 30% D: Change rate 30% or more

[0110] 3.3.Discharge stability The ink composition is filled into a specified ink container and left to stand at 60°C for 5 days. The container is then attached to a recording device (a modified PX-H6000 manufactured by Seiko Epson Corporation), the inkjet ink is ejected, and a solid pattern is printed on plain paper at a recording resolution of 1440 x 720 dpi. 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. The number of nozzles is 300. (Evaluation criteria) AA: No non-ejecting nozzles A: Number of non-ejecting nozzles is 1 to 9 B: 10 to 19 non-firing nozzles C: 20 to 29 non-firing nozzles D: The number of non-ejecting nozzles is 30 or more

[0111] 3.4.Color development (OD) The ink composition is filled into a printer (a modified PX-S840 printer manufactured by Seiko Epson). A solid pattern is printed using A4 plain paper (Xerox P paper) as the recording medium under the condition of a printing duty of 100%. After printing, the optical density (hereinafter also referred to as "OD") of the printed matter is measured, and the color development is evaluated according to the following evaluation criteria. (Evaluation criteria) A: OD 1.0 or higher B: OD 0.8 or more and less than 1.0 C: OD 0.6 or more and less than 0.8 D:OD less than 0.6

[0112] 4. Evaluation Results The composition of the carbon black dispersion used in each example and the evaluation results are shown in Table 1. Table 1 shows that the carbon black composition containing carbon black having a hydrophilic functional group and fulvic acid has excellent storage stability. The composition of the ink composition used in each example and the evaluation results are shown in Table 2. Table 2 shows that the ink composition containing the carbon black composition containing carbon black having a hydrophilic functional group and fulvic acid has excellent storage stability and ejection stability. [Explanation of symbols]

[0113] 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. Contains carbon black and fulvic acid, The carbon black has a hydrophilic functional group. Carbon black compositions for coloring.

2. The carbon black contains at least one of biomass-derived carbon black and recycled raw material-derived carbon black.

2. The carbon black composition of claim 1.

3. The DBP oil absorption of the carbon black is 50 to 180 mL / 100 g.

2. The carbon black composition of claim 1.

4. The average particle size of the primary particles of the carbon black is 10 to 50 nm.

2. The carbon black composition of claim 1.

5. 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.

2. The carbon black composition of claim 1.

6. The ratio (B / A) of the content B of the fulvic acid to the content A of the carbon black is 0.0001 to 0.

5.

2. The carbon black composition of claim 1.

7. the hydrophilic functional group contains at least one of a hydroxyl group and a carboxyl group; 2. The carbon black composition of claim 1.

8. Contains a dispersion medium containing water, the carbon black is dispersed in the dispersion medium, A pigment dispersion, 2. The carbon black composition of claim 1.

9. the hydrophilic functional group comprises an acidic group, the carbon black is a self-dispersing pigment dispersed in the dispersion medium; 9. The carbon black composition of claim 8.

10. the carbon black is a resin-dispersed pigment dispersed in the dispersion medium by a resin; 9. The carbon black composition of claim 8.

11. A carbon black composition comprising the carbon black composition according to any one of claims 1 to 10. Ink composition.

12. A recording method comprising the step of applying the ink composition according to claim 11 to a recording medium.

13. The ink composition according to claim 11 is applied to a recording medium. Recorded material.

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