Inkjet ink composition and recording method

Abstract

To provide a carbon black composition having excellent storage stability. The inkjet ink composition contains vegetable oil-derived carbon black, the vegetable oil-derived carbon black having an oxygen content of 0.5% by mass or more, and is a water-based ink.

Description

[Technical Field]

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

[0002] The inkjet recording method is capable of recording high-resolution images with a relatively simple device, and has been rapidly developed in various fields. For example, Patent Document 1 discloses a water-based inkjet ink composition for the purpose of providing an aqueous inkjet ink composition that is environmentally friendly and has excellent storage stability, the water-based inkjet ink composition comprising a colorant of biological origin, a dispersant of biological origin, and an organic solvent of biological origin, the organic solvent having a solubility parameter based on the Hansen method of 24.0 (cal / cm 3 ) 1 / 2 As described above, an ink composition containing a compound having a hydroxyl group is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-128719 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, environmentally friendly carbon black, such as plant-derived carbon black, has been attracting attention as a carbon black used as a coloring material for inkjet inks, but there is still room for improvement in terms of storage stability when used in inks. [Means for solving the problem]

[0005] The inkjet ink composition of the present invention contains vegetable oil-derived carbon black, and the vegetable oil-derived carbon black has an oxygen content of 0.5% by mass or more, and is a water-based ink.

[0006] The recording method of the present invention comprises depositing an ink using the above-mentioned ink-jet ink composition onto a recording medium. [Brief explanation of the drawings]

[0007] [Figure 1] Table 1 shows the compositions used in the examples and the evaluation results thereof. [Figure 2] 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

[0008] 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.

[0009] 1. Inkjet ink composition The inkjet ink composition according to this embodiment is a water-based ink that contains vegetable oil-derived carbon black, and the vegetable oil-derived carbon black has an oxygen content of 0.5% by mass or more.

[0010] Vegetable oil-derived carbon black is useful as a naturally-derived carbon black that can contribute to reducing carbon dioxide emissions. Furthermore, since it can be produced using the same manufacturing process as petroleum-derived carbon black, in that it is carbonized by burning a liquid raw material (oil), it has the advantage of being easy to control particle size. Furthermore, impurities can easily be reduced by refining the liquid raw material (vegetable oil). However, because vegetable oil-derived carbon black contains various functional groups and elements derived from the raw material, it is prone to reduced dispersion stability and the formation of foreign matter, which can lead to problems such as reduced storage stability of the inkjet ink composition. Furthermore, concerns can arise regarding abrasion resistance, color development, clogging recovery, and ejection and printing stability.

[0011] Therefore, in this embodiment, vegetable oil-derived carbon black having an oxygen content of 0.5% by mass or more is used.

[0012] Carbon black derived from vegetable oils, which have a high oxygen content, has many oxygen-containing functional groups such as carboxyl groups, phosphorus-containing groups, hydroxyl groups, and sulfo groups. Examples of phosphorus-containing groups include phosphorus-containing acid groups such as phosphate groups and phosphonate groups. Such oxygen-containing functional groups are generally hydrophilic and therefore are believed to contribute to improving dispersion stability in water. Furthermore, the presence of many oxygen-containing functional groups reduces the number of relatively hydrophobic non-oxygen-containing functional groups, which is believed to suppress the decrease in dispersion stability due to the non-oxygen-containing functional groups. Furthermore, the presence of many oxygen atoms also reduces the content of atoms other than oxygen in the carbon black, which is presumably also responsible for improving dispersion stability. Therefore, carbon black derived from vegetable oils with a high oxygen content is believed to have good dispersion stability and improve the storage stability of inkjet ink compositions.

[0013] Furthermore, vegetable oil-derived carbon black with many oxygen-containing functional groups readily reacts with calcium salts contained in absorbent recording media such as plain paper and recording media with ink-absorbing layers, and therefore tends to remain near the surface of the recording media, resulting in improved color development. Furthermore, vegetable oil-derived carbon black with many oxygen-containing functional groups also has a high affinity with resins, enabling the pigment to firmly adhere to the dispersant resin or resin particles on the recording media, resulting in excellent abrasion resistance.

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

[0015] 1.1.Pigments The pigment in this embodiment contains vegetable oil-derived carbon black having an oxygen content of 0.5% by mass or more. The use of vegetable oil-derived carbon black can contribute to reducing carbon dioxide emissions. Furthermore, when the vegetable oil-derived carbon black has an oxygen content of a predetermined percentage or more, dispersion stability is improved and storage stability is excellent. Furthermore, since the pigment is easily retained on recording media, color development is excellent, and further, affinity with resins is good, resulting in excellent abrasion resistance.

[0016] The oxygen content of the vegetable oil-derived carbon black in this embodiment is preferably 0.5% by mass or more, 1.0% by mass or more, 2.0% by mass or more, or 2.5% by mass or more. Furthermore, the oxygen content of the vegetable oil-derived carbon black is preferably 4.5% by mass or less, 3.5% by mass or less, or 3.0% by mass or less. When the oxygen content of the vegetable oil-derived carbon black is within the above range, the storage stability of the inkjet ink composition tends to be further improved.

[0017] The oxygen content of carbon black can be measured, for example, using a TCH600 manufactured by LECO Corp. Specifically, the sample is placed in a graphite crucible together with a flux, and melted and decomposed in a helium stream by resistance heating in an impulse furnace. The oxygen is converted to carbon dioxide, which is then detected and quantified using a thermal conductivity detector.

[0018] 1.1.1.Vegetable oil-derived carbon black The vegetable oil-derived carbon black in this embodiment is carbonized from vegetable oil, and is produced relatively easily using a manufacturing process similar to that of petroleum-derived carbon black. While the use of a combination or mixture of other feedstock oils, such as petroleum, which is typically used in oil furnace processes, as well as vegetable oils, is not excluded, an increase in the petroleum component reduces the contribution to reducing carbon dioxide emissions.

[0019] The method for producing the vegetable oil carbon black in this embodiment is not particularly limited, and known methods such as the furnace method, channel method, lamp method, etc. In addition, in the process of producing the raw material of the vegetable oil or its modified product, it is also possible to control the structure and primary particle size of the carbon black by adding an alkali agent such as potassium hydroxide or sodium hydroxide in addition to conditions such as the heating temperature and sample amount.

[0020] The raw material for the vegetable oil-derived carbon black is not particularly limited, but examples thereof include vegetable seed oil, tall oil, or wood tar, and modified products such as hydrogenated products of these vegetable seed oil, tall oil, or wood tar or derivatives thereof. Note that the modified products are vegetable oils modified within the scope of obtaining the effects of the present embodiment. Specific examples include avocado oil, linseed oil, almond oil, fennel oil, perilla oil, olive oil, orange oil, orange rougher oil, cocoa butter, chamomile oil, carrot oil, cucumber oil, apricot kernel oil, kukui nut oil, walnut oil, wheat germ oil, sesame oil, rice oil, rice bran oil, camellia oil, safflower oil, salad oil, shea butter, soybean oil, tea oil, evening primrose oil, camellia oil, corn oil, rapeseed oil, persic oil, safflower oil, castor oil, sunflower oil, grape seed oil, hazelnut oil, macadamia nut oil, cottonseed oil, meadowfoam oil, peanut oil, rosehip oil, turtle oil, cocoa butter, palm oil, palm kernel oil, Japan wax, coconut oil, wood tar oil, tall oil, wood creosote, and hydrogenated products thereof or modified products thereof, such as derivatives thereof.

[0021] The vegetable oil-derived carbon black having an oxygen content of 0.5% by mass or more is preferably surface-treated carbon black. The surface treatment of the carbon black is not particularly limited, but examples include a treatment in which a compound having an oxygen-containing functional group is reacted with the carbon black to introduce the oxygen-containing functional group, and a treatment in which the functional group of the carbon black is directly oxidized using ozone or the like to introduce the oxygen-containing functional group. The use of such carbon black tends to further improve storage stability.

[0022] Furthermore, vegetable oil-derived carbon black tends to have a higher oxygen content than carbon black made from petroleum, etc., because oxygen originating from the raw materials remains in the carbon black. Therefore, vegetable oil-derived carbon black with a high oxygen content can be obtained by selecting the combustion conditions during production and the vegetable oil as the raw material.

[0023] The average particle size of the vegetable oil-derived carbon black in this embodiment is preferably 80 to 350 nm, 90 to 200 nm, or 100 to 150 nm. When the average particle size of the vegetable oil-derived carbon black is within the above range, the storage stability and color development of the inkjet ink composition tend to be further improved.

[0024] The vegetable oil-derived carbon black is preferably a self-dispersing pigment or a pigment dispersed in a resin (hereinafter also referred to as a "resin-dispersed pigment"). The use of such carbon black tends to further improve storage stability.

[0025] Self-dispersing pigments are pigments 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 and / or chemical surface treatment to introduce hydrophilic functional groups onto the pigment surface, allowing the pigment to be dispersed in a solvent. Examples of hydrophilic functional groups include anionic groups such as carboxy groups, sulfo groups, and phosphorus-containing acid groups. Preferred self-dispersing pigments are those into which anionic groups have been introduced, i.e., pigments having anionic groups. When a self-dispersing pigment is used, it is preferable to add a fixing resin, which will be described later, to the pigment in order to ensure fixability to the recording medium.

[0026] Resin-dispersed pigments are pigments that are dispersed in a solvent and to which a dispersant resin is adsorbed, attached, or coated. Resin-dispersed pigments can be prepared, for example, by stirring the dispersant resin and pigment in water to disperse the pigment, or by stirring the dispersant resin and pigment in an organic solvent or the like, followed by transfer emulsification into an aqueous layer. When a resin-dispersed pigment is used as vegetable oil-derived carbon black, abrasion resistance tends to be improved even without the use of a fixing resin. A fixing resin may be used even when a resin-dispersed pigment is used.

[0027] The dispersant resin is not particularly limited, and any known resin that can be used in inkjet inks can be used, such as a dispersant resin made from a hydrophilic monomer such as (meth)acrylic acid or a salt thereof.

[0028] The content of the vegetable oil-derived carbon black is preferably 0.1 to 15 mass%, 1.0 to 10 mass%, 1.5 to 8.0 mass%, or 2.0 to 6.0 mass%, relative to the total amount of the inkjet ink composition. By setting the content of the vegetable oil-derived carbon black within the above range, intermittent ejection stability and continuous printing stability tend to be further improved.

[0029] 1.2.Organic solvents The inkjet ink composition of this embodiment may contain an organic solvent. By containing an organic solvent, the intermittent ejection stability of the inkjet ink composition tends to be further improved, and evaporation of water from the recording head when left unused for a long period of time can be effectively suppressed.

[0030] Examples of the organic solvent include water-soluble organic solvents such as polyols, glycol ethers, etc. The organic solvents may be used alone or in combination of two or more.

[0031] Examples of polyols include ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, propylene glycol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, and glycerin.

[0032] Among polyols, alkanediols having 5 or more carbon atoms are preferred as they further improve the permeability of ink into recording media. In particular, alkanediols having 6 to 10 carbon atoms are preferred, and alkanediols having 6 to 8 carbon atoms are more preferred. 1,2-alkanediols are particularly preferred.

[0033] Among polyols, alkanediols having four or fewer carbon atoms or glycols having a structure in which intermolecular hydroxyl groups of alkanediols having four or fewer carbon atoms are preferred, as these tend to further improve the moisturizing properties of the ink. In particular, alkanediols having three or fewer carbon atoms or glycols having a structure in which intermolecular hydroxyl groups of alkanediols having three or fewer carbon atoms are preferred, and alkanediols having two carbon atoms or glycols having a structure in which intermolecular hydroxyl groups of alkanediols having two carbon atoms are more preferred.

[0034] The glycol ethers may be monoethers or diethers of alkylene glycols, and alkyl ethers are preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ... alkylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether; and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0035] The normal boiling point of the organic solvent is preferably 160°C or higher, more preferably 170 to 300°C, 180 to 250°C, or 200 to 230°C.

[0036] The content of the organic solvent is preferably 3 to 50 mass %, 5 to 40 mass %, 10 to 30 mass %, 15 to 25 mass %, or 17 to 22 mass % relative to the total amount of the ink-jet ink composition. By keeping the content of the organic solvent within the above range, intermittent ejection stability tends to be further improved.

[0037] 1.3.Surfactants The inkjet ink composition of this embodiment may contain a surfactant. By containing a surfactant, intermittent ejection stability, continuous printing stability, and clogging recovery properties tend to be further improved.

[0038] The surfactant is not particularly limited, but examples thereof include silicone surfactants, acetylene glycol surfactants, and fluorine surfactants. The surfactants may be used alone or in combination of two or more.

[0039] Among these, it is preferable to contain either a silicone-based surfactant or an acetylene glycol-based surfactant. By using such a surfactant, intermittent ejection stability, continuous printing stability, and clogging recovery properties tend to be further improved.

[0040] Examples of silicone surfactants include polysiloxane compounds, polyether-modified organosiloxanes, etc. Commercially available silicone surfactants are not particularly limited, but examples include Silface SAG503A (manufactured by Nissin Chemical Industry Co., Ltd.).

[0041] The acetylene glycol surfactant is not particularly limited, but examples thereof include one or more selected from the group consisting of alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol. Commercially available products of such acetylene glycol surfactants are not particularly limited, but examples thereof include Surfynol 104PG50 (manufactured by Nissin Chemical Industry Co., Ltd.).

[0042] The content of the surfactant is preferably 0.05 to 5 mass %, 0.1 to 2 mass %, 0.2 to 1.5 mass %, or 0.7 to 1.2 mass % relative to the total amount of the ink-jet ink composition. By setting the content of the surfactant within the above range, intermittent ejection stability and continuous printing stability tend to be further improved.

[0043] 1.4. Fixing resin The inkjet ink composition of this embodiment may contain a fixing resin. The fixing resin in this embodiment is a resin that enhances the adhesion of the ink components to the recording medium, and is distinguished from the dispersant resin.

[0044] The fixing resin may be a water-soluble resin or resin particles. Among these, resin particles are preferred. By using such a fixing resin, abrasion resistance tends to be further improved. Furthermore, the resin particles may be supplied in the form of an emulsion or a powder.

[0045] Examples of fixing resins that can be used include acrylic resins such as polyacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid copolymer, vinyl acetate-acrylic ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid alkyl ester copolymer, and styrene-vinyl acetate-acrylic acid copolymer; urethane resins, which are resins containing urethane bonds formed by the reaction of an isocyanate group and a hydroxyl group; polyester resins, polyether resins, polyolefin resins, glue, gelatin, saponin, and other natural resins.

[0046] Among these, the fixing resin is preferably a urethane resin or an acrylic resin. Urethane resins have a high affinity with vegetable oil-derived carbon black, which has a high oxygen content, and therefore tend to further improve abrasion resistance. On the other hand, the use of acrylic resins tends to further improve clogging recovery.

[0047] Among these, it is particularly preferable to contain either a (meth)acrylic acid polymer or a styrene-(meth)acrylic acid polymer. By using such a fixing resin, abrasion resistance tends to be further improved. Among (meth)acrylic acid polymers, those polymerized from monomers in which at least one of alkyl (meth)acrylates having 1 to 24 carbon atoms and cyclic alkyl (meth)acrylates having 3 to 24 carbon atoms accounts for 70 mass % or more are more preferable. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, and behenyl (meth)acrylate. In addition, as monomers other than those mentioned above, for example, hydroxy(meth)acrylates having a hydroxyl group such as hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, and diethylene glycol(meth)acrylate, as well as urethane(meth)acrylate and epoxy(meth)acrylate can also be used.

[0048] As the fixing resin, commercially available products may be used, for example, urethane resins such as AP201 (manufactured by DIC Corporation) and acrylic resins such as Vinyblan 2687 (manufactured by Nissin Chemical Industry Co., Ltd.).

[0049] The content of the fixing resin is preferably 0.1 to 10% by mass, 1.2 to 6.0% by mass, 2.0 to 4.0% by mass, or 2.5 to 3.5% by mass, relative to the total amount of the inkjet ink composition. By setting the content of the fixing resin within the above range, abrasion resistance tends to be further improved. Furthermore, clogging recovery, ejection and printing stability, etc. also tend to be further improved.

[0050] 1.5. pH adjuster The inkjet 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.

[0051] The content of the pH adjuster is preferably 0 to 5 mass %, 0.01 to 3 mass %, 0.03 to 1 mass %, or 0.05 to 0.5 mass %, relative to the total amount of the ink-jet ink composition. By setting the content of the pH adjuster within the above range, storage stability, intermittent ejection stability, and continuous printing stability tend to be further improved.

[0052] 1.6. Chelating Agents The inkjet ink composition of this embodiment preferably contains a chelating agent. By including a chelating agent in the inkjet ink composition, aggregation or deterioration of the pigment component and resin component due to polyvalent metal salts contained as impurities can be prevented, and therefore storage stability tends to be further improved. Since vegetable oil-derived carbon black contains a large amount of impurities derived from the raw materials, the effect of including a chelating agent is more pronounced.

[0053] The chelating agent is not particularly limited, but examples thereof include ethylenediaminetetraacetic acid or a salt thereof, hexametaphosphoric acid or a salt thereof, pyrophosphoric acid or a salt thereof, metaphosphoric acid or a salt thereof, methylglycinediacetic acid or a salt thereof, L-glutaminediacetic acid or a salt thereof, L-aspartic acid diacetic acid or a salt thereof, diethylenetriaminepentaacetic acid or a salt thereof, gluconic acid or a salt thereof, citric acid or a salt thereof, nitrilo-3-propionic acid or a salt thereof, nitrilotrisphosphonic acid or a salt thereof, dihydroxyethylglycine or a salt thereof, hydroxyethyliminodiacetic acid or a salt thereof, 1,3-diamino-2-hydroxypropanetetraacetic acid or a salt thereof, hydroxyethylidenediphosphonic acid or a salt thereof, nitrilo-trimethylenephosphonic acid or a salt thereof, and phosphonobutanetricarcarboxylic acid or a salt thereof.

[0054] The content of the chelating agent is preferably 0 to 3 mass%, 0.01 to 0.5 mass%, 0.03 to 0.3 mass%, or 0.05 to 0.12 mass%, relative to the total amount of the ink-jet ink composition. By setting the content of the pH adjuster within the above range, storage stability, intermittent ejection stability, and continuous printing stability tend to be further improved.

[0055] 1.7.Water The inkjet ink composition of this embodiment is a water-based ink, which contains at least water as a solvent component.

[0056] The water content is preferably 40 to 99 mass%, 45 to 98 mass%, 50 to 98 mass%, 55 to 98 mass%, 60 to 98 mass%, 65 to 95 mass%, or 70 to 85 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.

[0057] 1.8.Other Ingredients The inkjet ink composition may contain components other than those described above, such as a dissolution aid, a viscosity modifier, an antioxidant, a preservative, an antifungal agent, and a corrosion inhibitor.

[0058] 2. Inkjet recording method The inkjet recording method according to this embodiment includes a step of ejecting the inkjet ink composition from a predetermined inkjet head and depositing it onto a recording medium.

[0059] 3. Inkjet recording device 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.

[0060] An example of an inkjet recording apparatus that can be used in this embodiment is shown in Figure 2. The inkjet recording apparatus according to this embodiment will be described in further detail with reference to Figure 2. 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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)).

[0072] 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.

[0073] 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.

[0074] 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 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]

[0075] 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.

[0076] In FIG. 1, Table 1 shows the composition of each ink composition of Examples and Comparative Examples and the evaluation results thereof.

[0077] 1. Preparation of Inkjet Ink Composition The components were mixed and thoroughly stirred to obtain the composition shown in Table 1, and then filtered under reduced pressure using a microfilter (Millipore) with a pore size of 5.0 μm to obtain the inkjet ink composition of each example. The numerical values ​​for each component shown in each example in the table represent % by mass unless otherwise specified. Furthermore, in the table, each numerical value represents the % by mass of the solid content of the component.

[0078] Details of the product ingredients used in Table 1 are as follows: [Pigment dispersion] Pigment dispersions 1 to 5 [Fixing resin] Urethane resin AP201 (DIC) Acrylic resin Vinyblan 2687 (manufactured by Nissin Chemical Industry Co., Ltd.) [Organic solvents] Propylene glycol 1,3-Propanediol 1,2-Hexanediol [Surfactants] Silface SAG503A (silicone surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) Surfynol 104PG50 (acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) [pH adjuster] Triisopropanolamine [Chelating agent] Ethylenediaminetetraacetic acid disodium salt [water] Ion-exchanged water

[0079] <Example of pigment dispersion preparation> [Pigment dispersion 1] 500 g of ion-exchanged water and 150 g of vegetable oil-derived carbon black (Printex Nature, Orion Engineered Carbon) were mixed and stirred for 30 minutes using a rocking mill with 1 mm zirconia beads to pre-wet the carbon black. Next, 4485 g of ion-exchanged water was added, and the mixture was dispersed five times using a Bead Mill Labostar Mini LMZ015 (Ashizawa Finetech). The average particle size of the pigment was 110 nm. The resulting dispersion was transferred to a high-pressure vessel and pressurized to 3 MPa. The carbon black surface was then treated by ozone oxidation using 100 ppm ozone water. The pH of the dispersion was then adjusted to 9.0 using 0.1 mol / L aqueous sodium hydroxide solution, and the pigment solids concentration was adjusted to obtain Pigment Dispersion 1. Pigment dispersion 1 contains carbon black, a self-dispersing pigment with -COONa groups bonded to the particle surface. The carbon black content is 15% by mass, and the oxygen content of the carbon black becomes 2.7% by mass after the above surface treatment.

[0080] [Pigment dispersion 2] 500 g of vegetable oil-derived carbon black (Printex Nature, Orion Engineered Carbon) with an oxygen content of 2.2% by mass was mixed with 1,000 g of resin dispersant (Solsperse J400, Lubrizol) and 14,000 g of water to obtain a mixture. The mixture was dispersed 10 times using a Labostar Mini LMZ015 bead mill (Ashizawa Finetech) with 0.2 mm zirconia beads, followed by centrifugation to remove impurities and vacuum filtration using a 5.0 μm pore size microfilter (Millipore). The pigment solids concentration was adjusted to obtain Pigment Dispersion 2 with a pH of 9.0. Pigment Dispersion 2 contains carbon black dispersed with a resin dispersant. The carbon black content is 15.0% by mass, the resin content is 7.5% by mass, and the oxygen content of the carbon black is 2.2% by mass.

[0081] [Pigment dispersion 3] Pigment dispersion 3 is prepared in the same manner as pigment dispersion 2, except that Printex Nature (manufactured by Orion Engineered Carbon) is heated in a reducing atmosphere to reduce the oxygen content to 0.45% by mass before use. The oxygen content of the carbon black is 0.45% by mass.

[0082] [Pigment dispersion 4] Pigment Dispersion 4 is prepared in the same manner as Pigment Dispersion 2, except that Printex Nature (manufactured by Orion Engineered Carbon) is replaced with petroleum-derived carbon black MA100 (manufactured by Mitsubishi Chemical) with an oxygen content of 0.3% by mass. The oxygen content of the carbon black is 0.3% by mass.

[0083] [Pigment dispersion 5] Pigment dispersion 5 is prepared in the same manner as pigment dispersion 1, except that ozone water having an ozone concentration of 150 ppm is used instead of the ozone water in pigment dispersion 1. The oxygen content of the carbon black is 3.2% by mass.

[0084] 2. Evaluation Method 2.1.Storage stability 20 g of each inkjet ink composition is placed in a 30 mL sample bottle, and storage stability is evaluated from the change in viscosity relative to the initial viscosity after leaving it at 70° C. for 7 days. (Evaluation criteria) A: Viscosity change is less than 1% B: Viscosity change is 1% or more but less than 5% C: Viscosity change is 5% or more but less than 10% D: Viscosity change is 10% or more

[0085] 2.2.Intermittent Discharge Stability Using a modified PX-S270T printer (manufactured by Seiko Epson Corporation), the ejection stability during intermittent printing was evaluated under an environment of 40°C temperature and 20% relative humidity. First, it was confirmed that the inkjet ink composition was ejected normally from all nozzles. Then, the inkjet ink composition was ejected onto A4-size superfine paper (manufactured by Seiko Epson Corporation), followed by a two-minute pause, and then ejected again onto A4-size photo paper. In the second ejection, the positional deviation of the dot from the first drop deposited on the A4-size photo paper relative to the target position was measured using an optical microscope. Based on the obtained dot positional deviation, the intermittent properties were evaluated according to the following evaluation criteria. (Evaluation criteria) A: Dot position deviation is 10 μm or less B: Dot misalignment is more than 10 μm and less than 20 μm C: Dot misalignment is greater than 20 μm and less than 30 μm D: Dot misalignment exceeds 30 μm

[0086] 2.3.Continuous printing stability The inkjet ink composition obtained above is filled into an ink cartridge of a printer PX-S270T (manufactured by Seiko Epson Corporation). Then, print samples are continuously printed on A4-size superfine paper (manufactured by Seiko Epson Corporation) at a resolution of 720 dpi (vertical) × 720 dpi (horizontal) at a print duty of 5% for up to 8 hours in an environment of a temperature of 40°C and a relative humidity of 20%, and the time until non-ejection or ejection disturbance is observed is measured. (Evaluation criteria) A: Even after 8 hours from the start of discharge, no non-discharge or discharge disturbance was observed even once. B: Non-discharge or disturbed discharge is observed 2 hours or more but less than 8 hours after the start of discharge. C: Non-discharge or disturbed discharge is observed 1 hour or more but less than 2 hours after the start of discharge. C: Non-discharge or disturbed discharge is observed within 1 hour from the start of discharge.

[0087] 2.4.Clogging recovery Using a PX-S270T printer (manufactured by Seiko Epson Corporation), the ink cartridge of this printer was filled with the inkjet ink composition obtained above, and printing was performed on A4-size superfine paper (manufactured by Seiko Epson Corporation) at a resolution of 720 dpi vertically and 720 dpi horizontally to confirm that the inkjet ink composition was ejected from all nozzles. The printer was then left for 30 days in an environment with a temperature of 40°C and a relative humidity of 20%. After leaving the printer, the ink composition was again ejected from all nozzles, and cleaning was repeatedly performed until printing equivalent to that at the initial stage was possible, and the number of cleanings was counted. Based on the number of cleanings, clogging recovery was evaluated according to the following evaluation criteria. (Evaluation criteria) A: The ink composition is ejected from all the nozzles after one or two cleanings. B: The ink composition is ejected from all nozzles after 3 to 5 screenings. C: The ink composition is ejected from all nozzles after five or more cleanings. D: The ink composition cannot be ejected from any of the nozzles during cleaning.

[0088] 2.5.Abrasion resistance Based on JIS L0849 2013, the abrasion resistance test was performed using a Gakushin-type abrasion resistance evaluation device AB-301 (manufactured by Tester Sangyo Co., Ltd.) under conditions of 1000 g load and 100 back and forth strokes. A PX-S270T printer (manufactured by Seiko Epson Corporation) was used to record a 1.0 inch x 0.5 inch solid print at 100% recording duty on film (25 μm thick plain OPP roll, manufactured by Toyobo Co., Ltd.). Next, a PX-G930 printer modified to increase the platen temperature was used to print at a dot density of 1440 dpi x 1440 dpi at 40°C. After printing, the print was heated at 50°C for 1 minute, and one day after printing, a dry cotton ball (dry abrasion test) was pressed against the solid print to evaluate abrasion resistance. The staining of the cotton ball, staining of non-recorded areas, and peeling of the printed area were then visually inspected, and the abrasion resistance was evaluated according to the following evaluation criteria. In this embodiment, the printing duty of a solid image printed under the condition that one ink droplet with a mass of 28 ng±10% is applied to a unit area of ​​1 / 600 inch x 1 / 600 inch is defined as 100%. (Evaluation criteria) A: There is almost no dirt on the gold cotton and no dirt on the non-recorded areas, and there is almost no peeling of the printed areas. B: There is some dirt on the gold cotton and non-recorded areas, but it is minimal, and the printed areas are hardly peeling off. C: There is dirt on the gold cotton and non-recorded areas, and the printed areas have peeled off to some extent. D: There is considerable dirt on the gold cotton and non-recorded areas, and the printed areas are peeling off.

[0089] 2.6.Color development Using a PX-S270T printer (manufactured by Seiko Epson Corporation), the ink cartridge of this printer was filled with ink, and printing was performed on A4-sized XeroXP paper (manufactured by Fujifilm Business Innovation Co., Ltd.) at a resolution of 720 dpi vertically and 720 dpi horizontally. After printing, the optical density (hereinafter also referred to as "OD") of the print was measured by measuring the average value of 10 points using an i1 Pro2 spectrophotometer manufactured by X-rite. (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

[0090] 3. Evaluation Results Table 1 shows the composition of the inkjet ink composition used in each example and the evaluation results. Table 1 shows that all of the inkjet ink compositions of the examples, which contain vegetable oil-derived carbon black, in which the oxygen content of the vegetable oil-derived carbon black is 0.5% by mass or more, and which are aqueous inks, have excellent storage stability. Furthermore, they also have good intermittent ejection stability, continuous printing stability, clogging recovery, abrasion resistance, and color development. In contrast, all of the comparative examples, which do not have such properties, have poor storage stability. Furthermore, the reference example containing petroleum-derived carbon black has an oxygen content of less than 0.5% by mass, but does not have poor storage stability. This shows that vegetable oil-derived carbon black poses storage stability issues. [Explanation of symbols]

[0091] 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 vegetable oil-derived carbon black, the vegetable oil-derived carbon black has an oxygen content of 0.5% by mass or more, It is a water-based ink, Inkjet ink composition.

2. The vegetable oil-derived carbon black has an oxygen content of 2.5% by mass or more. The ink-jet ink composition of claim 1 .

3. The vegetable oil-derived carbon black includes surface-treated carbon black. The ink-jet ink composition of claim 1 .

4. The vegetable oil-derived carbon black is a self-dispersed pigment or a resin-dispersed pigment dispersed in a resin. The ink-jet ink composition of claim 1 .

5. Contains a fixing resin, The ink-jet ink composition of claim 1 .

6. The fixing resin is a resin particle. The ink-jet ink composition of claim 5.

7. The fixing resin is a urethane resin or an acrylic resin. The ink-jet ink composition of claim 5.

8. Contains a chelating agent, The ink-jet ink composition of claim 1 .

9. Contains either a silicone surfactant or an acetylene glycol surfactant, The ink-jet ink composition of claim 1 .

10. Contains organic solvents, The ink-jet ink composition of claim 1 .

11. The vegetable oil-derived carbon black has anionic groups. The ink-jet ink composition of claim 1 .

12. A method for producing an ink jet recording medium, comprising a step of ejecting the ink jet ink composition according to any one of claims 1 to 11 from an ink jet head and depositing the ink jet ink composition on a recording medium. Recording method.

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