Ink for inkjet, ink set, ink medium set, and printing medium

Abstract

The present application provides an ink, which is an ink for inkjet containing a pigment, a water-soluble organic solvent, and an organic compound (wherein the above-mentioned pigment and the above-mentioned water-soluble organic solvent are excluded.), the logP value of the above-mentioned water-soluble organic solvent is less than 1.258, the interfacial tension of the above-mentioned organic compound against OPP is less than 20.7 mN / m, when the total mass of the above-mentioned water-soluble organic solvent in the ink is set as (A), and the total mass of the above-mentioned organic compound is set as (B), the value obtained from (B) / (A) is 0.01-0.50, and the surface tension at 25°C is less than 33.7 mN / m. In addition, an ink set and an ink medium set provided with the ink, and a printed medium having the ink attached thereto are provided.

Description

Technical Field

[0001] This invention relates to inkjet inks, ink groups, ink media groups, and printing media. Background Technology

[0002] Inkjet printing, a representative method of color printing, involves producing ink droplets that adhere to printing media such as paper for recording. In recent years, inkjet printing has seen increasing industrial applications, requiring its adaptability to various printing media.

[0003] Among printing media used in industrial applications, there are also non-absorbent ink media, represented by films. To print on such non-absorbent ink media, solvent-based inks with organic solvents as the main solvent and curable inks containing polymerizable monomers have been developed. However, these inks pose numerous safety concerns regarding the natural environment and living organisms, limiting their applications. Therefore, in recent years, the development of water-based inks with water as the main solvent has become increasingly popular (see, for example, Patent Documents 1-3).

[0004] However, the conventional inks proposed in Patent Documents 1-3 do not have sufficient wettability for non-absorbent media such as PET (polyethylene terephthalate) film and PP (polypropylene) film.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 5504890

[0008] Patent Document 2: Japanese Patent Application Publication No. 2020-125382

[0009] Patent Document 3: Japanese Patent Application Publication No. 2020-55943 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The objective of this invention is to provide an inkjet ink with good wettability to non-absorbent ink media, an ink group comprising the inkjet ink, an ink medium group comprising the inkjet ink or ink group and a printing medium, and a printing medium having each inkjet ink comprising the inkjet ink or ink group attached thereto.

[0012] Methods for solving problems

[0013] The specific means used to solve the above problems include the following implementation methods. 1)

[0015] Inkjet inks contain pigments, water-soluble organic solvents, and organic compounds (excluding the aforementioned pigments and water-soluble organic solvents).

[0016] The logP value of the aforementioned water-soluble organic solvent is less than 1.258.

[0017] When the interfacial tension between the following mixture and the OPP (biaxially oriented polypropylene) membrane at 25°C is defined as the interfacial tension of the aforementioned organic compound against the OPP membrane, the interfacial tension of the aforementioned organic compound against the OPP membrane is less than 20.7 mN / m. The aforementioned mixture is obtained by mixing 1 part by mass of the aforementioned organic compound, 9 parts by mass of 1,4-butanediol, and 90 parts by mass of purified water.

[0018] When the total mass of the aforementioned water-soluble organic solvent contained in the inkjet ink is defined as (A) and the total mass of the aforementioned organic compounds is defined as (B), the value obtained by (B) / (A) is 0.01 to 0.50.

[0019] The surface tension of the ink for inkjet printing is less than 33.7 mN / m at 25°C. 2)

[0021] The ink for inkjet printing as described in 1), wherein the interfacial tension of the aforementioned organic compound with respect to OPP is less than 19 mN / m. 3)

[0023] The ink for inkjet printing as described in 1), wherein the interfacial tension of the aforementioned organic compound with respect to OPP is less than 18 mN / m. 4)

[0025] The ink for inkjet printing as described in any one of 1) to 3), wherein the aforementioned water-soluble organic solvent comprises at least one selected from the group consisting of a compound represented by formula (1), a compound represented by formula (2), propylene glycol alkyl ethers, and diethylene glycol alkyl ethers.

[0026] [Chemical Formula 1]

[0027] HO-R 1 -OH (1)

[0028] (In equation (1), R) 1 This refers to a straight-chain or branched C4-C6 hydrocarbon group.

[0029] [Chemical Formula 2]

[0030]

[0031] (In equation (2), R) 2 (This indicates a hydrogen atom or a methyl group.) 5)

[0033] As described in 4), the inkjet ink contains at least one water-soluble organic solvent selected from the group consisting of 1,5-pentanediol, 1,4-butanediol, 1,6-hexanediol, propylene glycol monopropyl ether, diethylene glycol alkyl ether, and 3-methoxy-1-butanol. 6)

[0035] The ink for inkjet printing as described in any one of 1) to 5), wherein the aforementioned organic compound comprises at least one selected from the group consisting of polyoxyalkylene alkyl ethers, polyoxyalkylene aryl ethers, polyoxyethylene alkyl sulfates, and acetylenol surfactants. 7)

[0037] As described in 6), the inkjet ink contains at least one organic compound selected from the group consisting of polyoxyethylene naphthyl ether, polyoxyalkylene-2-ethylhexyl ether, polyoxyethylene lauryl sulfate, and acetylenol surfactants. 8)

[0039] The ink group includes any one of 1) to 7) inkjet ink and other inkjet inks different from the inkjet ink. 9)

[0041] An ink media group comprising any one of 1) to 7) ink for inkjet printing or the ink group described in 8), and a printing medium. 10)

[0043] A printing medium, wherein the inkjet ink described in any one of 1) to 7) is adhered to, or each inkjet ink contained in the ink group described in 8).

[0044] Invention Effects

[0045] According to the present invention, an inkjet ink with good wettability to non-absorbent ink media can be provided, an ink group comprising the inkjet ink, an ink medium group comprising the inkjet ink or ink group and a printing medium, and a printing medium having each inkjet ink comprising the inkjet ink or ink group attached thereon. Detailed Implementation

[0046] The following is a detailed description of specific embodiments in which the present invention is applied.

[0047] In this manual, "CI" refers to "Color Index".

[0048] In addition, unless otherwise specified, the terms "alkylene", "propylene", and "alkyl" are used in this specification to include both linear and branched structures.

[0049] Inkjet inks

[0050] The inkjet ink (hereinafter also simply referred to as "ink") involved in this embodiment is an inkjet ink containing pigments, water-soluble organic solvents, and organic compounds (excluding the aforementioned pigments and water-soluble organic solvents). The water-soluble organic solvent contains 10... The gP value is less than 1.258; when the interfacial tension between the mixture and the OPP film at 25°C is defined as the interfacial tension of the organic compound to the OPP, the interfacial tension of the organic compound to the OPP is less than 20.7 mN / m, wherein the mixture is obtained by mixing 1 part by mass of the organic compound, 9 parts by mass of 1,4-butanediol and 90 parts by mass of purified water; when the total mass of the water-soluble organic solvent contained in the ink according to this embodiment is set as (A) and the total mass of the organic compound is set as (B), the value obtained by (B) / (A) is 0.01 to 0.50; the surface tension of the inkjet ink at 25°C is less than 33.7 mN / m.

[0051] The surface tension of the ink according to this embodiment at 25°C is preferably 25.0 to 33.7 mN / m, more preferably 28.0 to 32.8 mN / m. By setting the surface tension of the ink within the above range, there is a tendency for the ink to have good wetting properties with non-absorbent media.

[0052] It should be noted that the ink involved in this embodiment preferably does not contain silicone-based surfactants. Silicone-based surfactants are surfactants that have intramolecular siloxane bonds (-Si-O-Si-).

[0053] The components contained in the ink according to this embodiment will be described in detail below. It should be noted that each component described below may be used alone or in combination with two or more components.

[0054] [pigment]

[0055] As pigments, examples include inorganic pigments, organic pigments, extender pigments, and hollow particles.

[0056] Examples of inorganic pigments include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides.

[0057] In this embodiment, when the ink is a black ink and the pigment is an inorganic pigment, the inorganic pigment contained in the black ink is preferably a thermal cracking carbon black, acetylene black, oil furnace carbon black, gas furnace carbon black, lampblack, gas black, or channel black. Specific examples of carbon black include the Raven series manufactured by Columbia Carbon Co., Ltd.; the Monarch, Regal, and Mogul series manufactured by Cabot Corporation; the ColorBlack, Printex, SpecialBlack, and Nerox series manufactured by Orion Engineered Carbons Co., Ltd.; and the MA series, MCF series, No. 25, No. 33, No. 40, No. 47, No. 52, No. 900, and No. 2300 manufactured by Mitsubishi Chemical Corporation; and so on.

[0058] In this embodiment, when the ink is white and the pigment is inorganic, examples of inorganic pigments in the white ink include oxides, nitrides, or nitrides of metals such as zinc, silicon, aluminum, titanium, strontium, and zirconium; inorganic compounds such as glass and silicon dioxide; and so on. Among these, titanium dioxide and zinc oxide are preferred.

[0059] Examples of organic pigments include azo, diazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, violet ketone, thioindigo, anthraquinone, and quinophthalone. Among these, diazo pigments are preferred.

[0060] Specific examples of organic pigments include CI pigments such as Yellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 128, 129, 138, 139, 150, 151, 154, 155, 180, 185, 193, 199, 202, and 213; and CI pigments such as Red 5, 7, 12, 48, 48, 1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 168, 177, and 178. Red pigments such as 179, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 269, and 272; CI pigments Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, and 80; CI pigments Violet 19, 23, 29, 37, 38, and 50; CI pigments Orange 13, 16, 43, 68, 69, 71, and 73; CI pigments Green 7, 36, and 54; CI pigment Black 1; and so on. Among these, CI pigment Blue 15:4 is preferred.

[0061] Examples of extender pigments include silica, calcium carbonate, talc, clay, barium sulfate, and fumed silica. Extender pigments are often used in combination with other pigments.

[0062] Hollow particles, for example, can be used as known hollow particles described in U.S. Patent No. 4,880,465, Japanese Patent No. 3,562,754, Japanese Patent No. 6,026,234, Japanese Patent No. 5,459,460, Japanese Unexamined Patent Application Publication No. 2003-268,694, Japanese Patent No. 4,902,216, etc., and are particularly preferred for use as white pigments.

[0063] The average particle size of the pigment is preferably 30–300 nm, more preferably 50–250 nm. In this specification, the term "average particle size" refers to the average particle size measured using laser scattering.

[0064] The pigment content is preferably 1 to 30% by mass, more preferably 1 to 10% by mass, and even more preferably 2 to 8% by mass, relative to the total mass of the ink involved in this embodiment.

[0065] [Water-soluble organic solvents]

[0066] As a water-soluble organic solvent, there are no particular restrictions as long as the organic solvent has a logP value less than 1.258. The logP value refers to the octanol / water partition coefficient; a higher value indicates higher hydrophobicity. The logP value can be expressed as "ClogP," calculated using ChemDraw Professional ver. 16.0 from PerkinElmer. Preferably, the logP value of the water-soluble organic solvent is greater than -5.420 and less than 1.258.

[0067] Examples of water-soluble organic solvents with a logP value less than 1.258 include, for example, C1-C6 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, and tert-butanol; carboxylic amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-methylpyrrolidone-2-one; and 1,3-dimethylimidazolidine-2-one and 1,3-dimethylhexahydropyrimidine. Cyclic ureas such as pyridin-2-one; ketones, ketols, or carbonates such as acetone, 2-methyl-2-hydroxypentan-4-one, and ethylene carbonate; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and polyethylene glycol (preferably with a molecular weight of 400, 800, 1540, or higher). Polyethylene glycol, polypropylene glycol, thiodiethylene glycol, dithiodiethylene glycol, and other mono- or oligomeric or polyalkylene glycols or thioglycols with C2-C6 alkylene units; glycerol, diglycerol, hexane-1,2,6-triol, trimethylolpropane, and other C3-C9 polyols (triols); mono-, di-, or triethylene glycol alkyl ethers, mono-, di-, or tripropylene glycol alkyl ethers, ethylene glycol monophenyl ethers, diethylene glycol monophenyl ethers, triethylene glycol monophenyl ethers, ethylene glycol monobenzyl ethers, di-... Glycol monobenzyl ether, triethylene glycol monobenzyl ether, and other glycol ethers; 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethylhexane-1,3-diol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and other alkane diols; etc.

[0068] As a water-soluble organic solvent, the preferred compounds are those represented by formula (1), those represented by formula (2), propylene glycol alkyl ethers, and diethylene glycol alkyl ethers.

[0069] [Chemical Formula 3]

[0070] HO-R 1 -OH (1)

[0071] [Chemical Formula 4]

[0072]

[0073] In the above formula (1), R 1 It represents a straight-chain or branched C4-C6 hydrocarbon group. 1,4-Butanediol, 1,5-pentanediol and 1,6-hexanediol are preferred as compounds represented by the above formula (1).

[0074] In equation (2) above, R 2 The symbol represents a hydrogen atom or a methyl group. 3-methoxy-1-butanol and 3-methoxy-3-methyl-1-butanol are preferred as compounds represented by formula (2) above.

[0075] Examples of propylene glycol alkyl ethers include, for example, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and other propylene glycol monoalkyl ethers; propylene glycol diethyl ether and other propylene glycol dialkyl ethers; and so on.

[0076] Examples of diethylene glycol alkyl ethers include, for example, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, and other diethylene glycol monoalkyl ethers; diethylene glycol dimethyl ether, diethylene glycol butyl methyl ether, and other diethylene glycol dialkyl ethers; and so on.

[0077] In particular, the water-soluble organic solvent preferably comprises at least one selected from the group consisting of 1,5-pentanediol, 1,4-butanediol, 1,6-hexanediol, propylene glycol monopropyl ether, diethylene glycol alkyl ether, and 3-methoxy-1-butanol, and more preferably comprises at least one selected from the group consisting of 1,5-pentanediol, 1,4-butanediol, propylene glycol monopropyl ether, diethylene glycol butyl methyl ether, and 3-methoxy-1-butanol.

[0078] These water-soluble organic solvents are compounds that have achieved a balance between hydrophilicity and hydrophobicity, and are soluble in both water contained in the ink and the aforementioned organic compounds. It is believed that due to this property, even in water-based inks where water constitutes a large portion of the total ink mass, the aforementioned organic compounds can be stably dissolved, preventing phase separation of the ink.

[0079] The content of water-soluble organic solvent is preferably 1 to 20% by mass, more preferably 1 to 15% by mass, even more preferably 1 to 10% by mass, and particularly preferably 3 to 7% by mass, relative to the total mass of the ink involved in this embodiment.

[0080] [Organic compounds]

[0081] As the organic compound, an organic compound with an interfacial tension of less than 20.7 mN / m to OPP is used. The interfacial tension of the organic compound to OPP is preferably 19 mN / m or less, more preferably 18 mN / m or less. In this specification, "interfacial tension to OPP" refers to the interfacial tension at 25°C between the mixture (1 part by mass), 1,4-butanediol (9 parts by mass), and purified water (90 parts by mass) and the OPP membrane, which can be calculated using Young's formula from the contact angle of the mixture to the OPP membrane. For example, PYLEN Film-OT (P2102) manufactured by Toyobo Co., Ltd. is used as the OPP membrane.

[0082] Organic compounds with an interfacial tension of less than 20.7 mN / m (OPP) exhibit a property of readily orienting at the ink-media interface after the ink has settled onto the printing medium. It is believed that this property reduces the interfacial tension at the ink-media interface, promoting ink wetting and spreading on the printing medium, thereby resulting in excellent wetting properties.

[0083] As an organic compound, it preferably includes at least one selected from the group consisting of polyoxyalkylene alkyl ethers, polyoxyalkylene aryl ethers, polyoxyethylene alkyl sulfates, and acetylenol surfactants, and more preferably includes at least one selected from the group consisting of polyoxyethylene naphthyl ethers, polyoxyalkylene-2-ethylhexyl ethers, polyoxyethylene lauryl sulfates, and acetylenol surfactants.

[0084] Specific examples of polyoxyalkylene alkyl ethers include polyoxyalkylene-2-ethylhexyl ether, and commercially available products include Tergitol EH3 (manufactured by The Dow Chemical Company). Other specific examples of polyoxyalkylene alkyl ethers include polyoxyalkylene C12 / C15 alkyl ethers, and commercially available products include GENAPOLEP2544 (manufactured by Clariant Japan KK).

[0085] Specific examples of polyoxyalkylene aryl ethers include polyoxyethylene β-naphthyl ether, and commercially available products include BLAUNON BN-3, BN-10, and BN-25 (manufactured by Aoki Oils & Fats Co., Ltd.).

[0086] Specific examples of polyoxyethylene alkyl sulfates include polyoxyethylene lauryl ether ammonium sulfate, and commercially available products include HITENOL LA-10, LA-12, and LA-16 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.).

[0087] Specific examples of alkynyl diol surfactants include SURFYNOL 485 (manufactured by Evonik Industries AG).

[0088] Among them, BLAUNON BN-3 (polyoxyethylene β-naphthyl ether), Terg itol EH3 (polyoxyalkylene glycol 2-ethylhexyl ether), HITENOL LA-10 (polyoxyethylene lauryl ether ammonium sulfate), GENAPOL EP2544 (polyoxyalkylene C12 / C15 alkyl ether), and acetylenol surfactants (SURFYNOL 485) are preferred.

[0089] From the viewpoint of wetting the non-absorbent medium of the ink, the content of organic compounds is preferably 0.05 to 1.5% by mass, more preferably 0.10 to 1% by mass, and even more preferably 0.3 to 0.7% by mass, relative to the total mass of the ink involved in this embodiment.

[0090] Furthermore, when the total mass of the water-soluble organic solvent contained in the ink according to this embodiment is set as (A) and the total mass of the organic compound is set as (B), the value obtained by (B) / (A) is 0.01 to 0.50, preferably 0.01 to 0.3, more preferably 0.05 to 0.2, and even more preferably 0.075 to 0.125.

[0091] [water]

[0092] The ink described in this embodiment may contain water. Preferably, the water is low in impurities such as metal ions, i.e., ion-exchanged water, distilled water, etc.

[0093] When the ink according to this embodiment contains water, its content relative to the total mass of the ink according to this embodiment is preferably 50 to 90% by mass, more preferably 60 to 90% by mass, and even more preferably 60 to 80% by mass.

[0094] [Surface tension modifier]

[0095] The ink according to this embodiment preferably contains a surface tension modifier (excluding the aforementioned organic compounds). In other words, the ink according to this embodiment preferably combines the aforementioned organic compounds and the surface tension modifier.

[0096] Examples of surface tension modifiers include SURFYNOL 420 and 440 (manufactured by Evonik Industries AG), with SURFYNOL 440 being preferred.

[0097] SURFYNOL 420 and 440 are both highly hydrophobic compounds, possessing the property of readily orienting on the ink surface (the ink-air interface) after the ink has settled onto the printing medium. It is believed that this property reduces the surface tension of the ink, promoting wetting and spreading on the printing medium, thus exhibiting excellent wetting properties even in water-based inks.

[0098] When the ink according to this embodiment contains a surface tension modifier, its content relative to the total mass of the ink according to this embodiment is preferably 0.3 to 10% by mass, more preferably 0.3 to 2% by mass, and even more preferably 0.3 to 1% by mass.

[0099] [Dispersant]

[0100] The ink according to this embodiment may contain a dispersant. Examples of dispersants include copolymers composed of at least two monomers selected from the following (preferably at least one of which is hydrophilic): styrene and its derivatives; vinylnaphthalene and its derivatives; aliphatic alcohol esters of α,β-olefinically unsaturated carboxylic acids; (meth)acrylic acid and its derivatives; maleic acid and its derivatives; itaconic acid and its derivatives; fumaric acid and its derivatives; vinyl acetate, vinyl alcohol, vinylpyrrolidone, acrylamide, and their derivatives; etc. Examples of hydrophilic monomers include acrylic acid, methacrylic acid, and other monomers that retain a carboxyl group after polymerization.

[0101] Examples of such copolymers include styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylate copolymers, (meth)acrylate-(meth)acrylic acid copolymers, polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymers, and styrene-maleic acid copolymers. Among these, styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylate copolymers, (meth)acrylate-(meth)acrylic acid copolymers, and polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymers are preferred; styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylate copolymers, and (meth)acrylate-(meth)acrylic acid copolymers are more preferred; (meth)acrylate-(meth)acrylic acid copolymers are even more preferred; and methacrylate-methacrylic acid copolymers are particularly preferred. Examples of copolymer types include block copolymers, random copolymers, and graft copolymers. These copolymers may also be in the form of salts.

[0102] It should be noted that in this specification, the term "(meth)propylene-" is used to include both "propylene-" and "methpropylene-". The same applies to "(meth)acrylate", etc.

[0103] Dispersants can be synthesized or obtained in the form of commercially available products.

[0104] As a dispersant obtained through synthesis, for example, the AB block polymer disclosed in International Publication No. 2013 / 115071 can be cited. The monomer constituting the A block of the AB block polymer disclosed in International Publication No. 2013 / 115071 is at least one monomer selected from (meth)acrylic acid and linear or branched C4 alkyl (meth)acrylates, preferably at least one monomer selected from methacrylic acid and n-butyl methacrylate, more preferably both monomers. Furthermore, the monomer constituting the B block of the AB block polymer disclosed in International Publication No. 2013 / 115071 is at least one monomer selected from benzyl methacrylate and benzyl acrylate, preferably benzyl methacrylate. As specific examples of AB block polymers, the block copolymers disclosed in Synthesis Examples 3 to 8 of International Publication No. 2013 / 115071 can be cited.

[0105] Examples of dispersants available commercially, such as Joncyrl 62, 67, 68, 678, 687 (styrene-acrylic copolymers manufactured by BASF); AronAC-10SL (polyacrylic acid manufactured by Toa Synthetic Co., Ltd.); BYKJET 9151, 9152, 9170, 9171 (wetting and dispersing agents manufactured by BYK Corporation); and so on.

[0106] The mass-average molecular weight (MW) of the dispersant is preferably 3,000 to 50,000, more preferably 7,000 to 25,000. The mass-average molecular weight of the dispersant can be determined by gel permeation chromatography (GPC). Specifically, an HLC-8320GPC (manufactured by TOSOH Corporation) can be used as the GPC apparatus, two TSK gel Super MultIpore HZ-H (manufactured by TOSOH Corporation, inner diameter 4.6 mm × 15 cm) columns can be used, tetrahydrofuran can be used as the eluent, and TSK Standard (manufactured by TOSOH Corporation) can be used as the standard sample for determination.

[0107] The acid value of the dispersant is preferably 50-300 mg KOH / g, more preferably 80-275 mg KOH / g, and even more preferably 80-250 mg KOH / g.

[0108] Dispersants can be used in a state where they are mixed with pigments. Alternatively, they can be used to coat part or all of the surface of the pigment with the dispersant. Or, both states can be used in combination.

[0109] When the ink according to this embodiment contains a dispersant, the ratio of the total mass of the dispersant to the total mass of the pigment is preferably 0.01 to 1.0, more preferably 0.05 to 0.6, and even more preferably 0.1 to 0.5.

[0110] [Fixing resin]

[0111] The ink according to this embodiment may contain a fixing resin. By including a fixing resin in the ink according to this embodiment, there is a tendency to improve the image fastness, such as water resistance, abrasion resistance, and alcohol resistance, of the image printed onto the printing medium. As the fixing resin, at least one selected from polymers and waxes is preferred.

[0112] Commercially available polymer emulsions are available in emulsion form. Examples of commercially available polymer emulsions include: SUPERFLEX 420, 470, and 890 (all urethane resin emulsions manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.); HYDRAN HW-350, HW-178, HW-163, HW-171, AP-20, AP-30, WLS-201, and WLS-210 (all urethane resin emulsions manufactured by DIC Co., Ltd.); 0569, 0850Z, and 2108 (all styrene-butadiene resin emulsions manufactured by JSR Co., Ltd.); AE980, AE981A, AE982, AE986B, and AE104 (all acrylic resin emulsions manufactured by E-TEC Co., Ltd.); and NeoCryl A-1105, A-1125, and A-1127 (all DSM Coatings). Acrylic resin emulsion manufactured by Resin; etc.

[0113] As a wax, both natural and synthetic waxes can be used.

[0114] As natural waxes, examples include petroleum-based waxes such as paraffin wax and microcrystalline wax; lignite-based waxes such as lignite wax; plant-based waxes such as carnauba wax and candelilla wax; animal and plant-based waxes such as beeswax and lanolin; and so on.

[0115] Examples of synthetic waxes include, for example, polyalkylene waxes (preferably polyC2-C4 alkylene waxes), oxidized polyalkylene waxes (preferably oxidized polyC2-C4 alkylene waxes), and paraffin wax. Among these, polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, and paraffin wax are preferred.

[0116] To prevent inkjet head clogging, the average particle size of the wax is preferably 50 nm to 5 μm, more preferably 100 nm to 1 μm.

[0117] Waxes are available in commercially available emulsion form. Commercially available wax emulsions include, for example, CERAFLOUR 925, 929, 950, 991, AQUACER 498, 515, 526, 531, 537, 539, 552, 1547, AQUAMAT 208, 263, 272; MINE RPOL 221 (all manufactured by BYK); Mitsui Hi-WAX NL100, NL200, NL500, 4202E, 1105A, 2203A, NP550, NP055, NP505 (all manufactured by Mitsui Chemicals Co., Ltd.); KUE-100, 11 (all manufactured by Sanyo Chemical Industry Co., Ltd.); HYTEC P-5300, E-6500, 9015, 6400 (all manufactured by Toho Chemical Industry Co., Ltd.); and so on.

[0118] When the ink according to this embodiment contains fixing resin, its content relative to the total mass of the ink according to this embodiment is preferably 1 to 20% by mass, more preferably 3 to 15% by mass. By making the content of fixing resin 1% by mass or more, there is a tendency to exhibit good fixing properties for printing media. In addition, by making the content of fixing resin 20% by mass or less, there is a tendency to improve the ink's ejectibility and storage stability.

[0119] [Other ingredients]

[0120] The ink described in this embodiment may contain ink modifiers such as mildew inhibitors, preservatives, pH adjusters, chelating agents, rust inhibitors, defoamers, water-soluble ultraviolet absorbers, and antioxidants, as needed. The content of each ink modifier can be arbitrarily set according to the intended use of the ink.

[0121] (Anti-mold agent)

[0122] Examples of antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyrithione sodium-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one and its salts.

[0123] (preservative)

[0124] Examples of preservatives include compounds of the following types: organosulfur, organonitrogen-sulfur, organohalogen, halogenated aryl sulfone, iodopropynyl, halogenated alkyl sulfone, nitrile, pyridine, 8-hydroxyquinoline, benzothiazole, isothiazolinyl, dithiol, pyridine oxide, nitrobenzene, organotin, phenol, quaternary ammonium salt, triazine, thiazine, acetanilide, adamantane, dithiocarbamate, indanone bromide, benzyl bromoacetate, and inorganic salts. Specific examples of organohalogen compounds include sodium pentachlorophenate. Specific examples of pyridine oxide compounds include sodium 2-mercaptopyridine-1-oxide. Specific examples of isothiazolinone compounds include 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one magnesium chloride, 5-chloro-2-methyl-4-isothiazolin-3-one calcium chloride, and 2-methyl-4-isothiazolin-3-one calcium chloride. Other examples of preservatives and fungicides include anhydrous sodium acetate, sodium sorbate, sodium benzoate, and Arch Chemicals' trade names Proxel GXL(S), Proxel LV, and Proxel XL-2(S).

[0125] (pH adjuster)

[0126] Examples of pH adjusters include, for example, alkanolamines such as diethanolamine, triethanolamine, and N-methyldiethanolamine; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide (ammonia); carbonates of alkali metals such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; inorganic bases such as disodium phosphate; and so on.

[0127] (chelating agent)

[0128] Examples of chelating agents include disodium ethylenediaminetetraacetate, sodium hypotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uracil diacetate.

[0129] (Rust inhibitor)

[0130] Examples of rust inhibitors include acidic sulfites, sodium thiosulfate, ammonium mercaptoacetate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

[0131] (Defoamer)

[0132] Examples of defoamers include silica-based mineral oil-based, olefin-based, and acetylene-based defoamers. Commercially available defoamers include, for example, SUR FYNOL DF37, DF58, DF110D, DF220, MD-20, and OLFINE SK-14 manufactured by Shin-Etsu Chemical Co., Ltd.

[0133] (Water-soluble UV absorber)

[0134] Examples of water-soluble ultraviolet absorbers include sulfonated benzophenone compounds, benzotriazole compounds, salicylic acid compounds, cinnamic acid compounds, and triazine compounds.

[0135] (Antioxidants)

[0136] As antioxidants, various organic and metal complex-based anti-fading agents can be used, for example. Examples of organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromophores, alkoxyanilines, and heterocyclic compounds.

[0137] [Ink Preparation Method]

[0138] There are no particular limitations on the method for preparing the ink according to this embodiment, and known preparation methods can be used. As an example, for instance, the following method can be used: preparing an aqueous dispersion containing pigments and dispersants, adding a water-soluble organic solvent, an organic compound, and an ink modifier as needed to the dispersion, and mixing them.

[0139] Examples of methods for preparing dispersions include phase inversion emulsification, acid precipitation, interfacial polymerization, in-situ polymerization, liquid-based solidification coating, coagulation (phase separation), liquid-based drying, melt dispersion cooling, gas suspension coating, and spray drying. Among these, phase inversion emulsification, acid precipitation, and interfacial polymerization are preferred, with phase inversion emulsification being more preferred.

[0140] In the case of preparing a dispersion using a phase inversion emulsification method, for example, a dispersant is dissolved in an organic solvent such as 2-butanone, and an aqueous solution of a neutralizing agent is added to prepare an emulsion. A pigment is then added to the resulting emulsion for dispersion treatment. From the liquid obtained as described above, the organic solvent and a portion of water are removed by distillation under reduced pressure, thereby obtaining the desired dispersion.

[0141] Dispersion processing can be performed using sand mills (bead mills), roller mills, ball mills, paint shakers, ultrasonic dispersers, microfluidic homogenizers, etc. For example, when using a sand mill, beads with a particle size of approximately 0.01–1 mm can be used, and the bead filling rate can be appropriately set for dispersion processing. The dispersion obtained as described above can be subjected to operations such as filtration and centrifugation to ensure that the particle size contained in the dispersion is uniform. If foaming occurs during the preparation of the dispersion, a trace amount of a known defoamer such as an organosilicon-based or acetylenic diol-based agent can be added.

[0142] For the inks involved in this embodiment, it is preferable to have a low content of inorganic impurities such as chlorides of metal cations (e.g., sodium chloride) and sulfates of metals (e.g., sodium sulfate). Such inorganic impurities are often found in commercially available pigments. The standard for the content of inorganic impurities is approximately 1% by mass or less relative to the total mass of the pigment, with the lower limit being below the detection limit of the analytical device; ideally, 0% by mass is preferred. Methods for obtaining pigments with low inorganic impurity content include, for example, using a reverse osmosis membrane; suspending and stirring the solid pigment in a mixed solvent of C1-C4 alcohols such as methanol and water, filtering and separating the pigment, and then drying it; using an ion exchange resin to exchange and adsorb inorganic impurities; and so on.

[0143] The ink involved in this embodiment is preferably pre-microfiltered. Microfiltration can be performed using membrane filters, glass filter paper, etc. The pore size of the filter or the like used for microfiltration is typically 0.5–20 μm, preferably 0.5–10 μm.

[0144] The ink described in this embodiment exhibits excellent storage stability, redispersibility, color development, and chroma. Furthermore, images recorded using the ink described in this embodiment demonstrate excellent water resistance, lightfastness, heat resistance, and other durability properties. Additionally, the ink described in this embodiment exhibits minimal coating unevenness during image formation and excellent image formation properties.

[0145] <Ink Group, Ink Media Group>

[0146] The ink group involved in this embodiment includes the ink involved in this embodiment as described above, and other inks different from the ink involved in this embodiment. As for the other inks, there are no particular limitations as long as they are inks that constitute different structures from the ink involved in this embodiment, but inks with different hues from the ink involved in this embodiment are preferred.

[0147] In addition, the ink group involved in this embodiment includes the ink or ink group involved in this embodiment described above, and the printing medium.

[0148] There are no particular limitations on the printing medium, but a printing medium with poor ink absorption or non-absorbent ink is preferred, and a non-absorbent ink printing medium is more preferred. Examples of printing media with poor ink absorption include ordinary paper without an ink-receiving layer, media used in gravure printing, offset printing, art paper, coated paper, matte paper, and cast-coated paper. Examples of printing media with non-absorbent ink include, for example, PET (polyethylene terephthalate) film, PP (polypropylene) film, vinyl chloride sheet, glass, and rubber.

[0149] <Inkjet Printing Methods>

[0150] The inkjet printing method described in this embodiment is a printing method that involves ejecting droplets of ink as described in this embodiment according to a printing signal and allowing them to adhere to a printing medium. There are no particular limitations on the ink nozzles or other components of the inkjet printer used for ejecting the ink; they can be appropriately selected depending on the purpose.

[0151] The inkjet printing method described in this embodiment also includes the following methods: a method of improving image quality by ejecting a large quantity of ink with a low pigment content in a small volume; a method of improving image quality by using multiple inks of substantially the same hue but with different pigment contents; a method of improving the fixing property of pigment onto the printing medium by using colorless transparent ink and pigment-containing ink together; and so on.

[0152] As an inkjet printing method, known methods can be used. Examples include charge control, on-demand inkjet (also known as pressure pulse), acoustic inkjet, and thermal inkjet. Furthermore, the inkjet printing method can be either multi-pass or single-pass printing. In industrial inkjet printers, single-pass printing using a linear printhead is preferred for achieving high printing speeds.

[0153] When printing on printing media, for example, a container containing ink (ink can) is filled into a designated position on an inkjet printer, and printing is performed on the printing media using the printing method described above. It should be noted that by filling containers containing inks of various colors into the designated positions on an inkjet printer and performing printing on the printing media using the printing method described above, full-color printing can also be achieved.

[0154] When using printing media without an ink-receiving layer, it is preferable to perform a surface modification treatment on the printing media to improve the fixing properties of the pigments. Examples of surface modification treatments include corona discharge treatment, plasma treatment, and flame treatment. It is generally known that the effect of surface modification treatment decreases over time. Therefore, it is preferable to perform the surface modification treatment process and the inkjet printing process consecutively, and more preferably to perform the surface modification treatment process just before the inkjet printing process.

[0155] Regarding all the above-mentioned matters, the combination of preferred items is more preferred, and the combination of more preferred items is even more preferred. The same applies to combinations of preferred items and more preferred items, and combinations of more preferred items and even more preferred items.

[0156] Example

[0157] The present invention will be described in more detail below through embodiments, but the present invention is not limited to the embodiments.

[0158] In the embodiments, unless otherwise specified, "parts" refers to parts by mass and "%" refers to percentage by mass. Furthermore, when it is necessary to quantify the solid pigment component in the dispersion, it is determined by the dry weight method using MS-70 manufactured by A&D Co., Ltd. The solid pigment component is a converted value obtained by calculating the solid pigment component solely from the total amount of solid components.

[0159] <Preparation Example 1: Preparation of Pigment Dispersion DP1>

[0160] Additional experiments were conducted on Synthesis Example 3 of International Publication No. 2013 / 115071, thereby obtaining a block copolymer. The obtained block copolymer had an acid value of 105 mg KOH / g and a mass-average molecular weight of 25,000. The obtained block copolymer (6 parts) was dissolved in 2-butanone (30 parts) to prepare a homogeneous solution. A liquid obtained by dissolving 28% ammonia solution (0.68 parts) in deionized water (53 parts) was added to this liquid, and the mixture was stirred for 1 hour to obtain an emulsion. CI Pigment Blue 15:4 (manufactured by Dainishi Chemical Industry Co., Ltd., CHRO MOFINE BLUE 4851) (20 parts) was added to this emulsion, and the mixture was dispersed in a sand mill at 1500 rpm for 15 hours. Add 100 parts of ion-exchanged water dropwise to the obtained liquid, filter to remove the dispersing beads, and then use an evaporator to remove 2-butanone and a portion of the water under reduced pressure by distillation to obtain a pigment dispersion with a solid content of 12%. The obtained pigment dispersion is designated as "DP1".

[0161] <Preparation Example 2: Preparation of Pigment Dispersion DP2>

[0162] BYKJET 9151 (manufactured by BYK Corporation) (8 parts) was dissolved in ion-exchanged water (72 parts) and stirred for 1 hour. Chromofine Blue 15:4 (manufactured by Daihisei Kagaku Co., Ltd., Chromofine Blue 4851) (20 parts) was added to the resulting solution, and the mixture was dispersed in a sand mill at 1500 rpm for 15 hours. Ion-exchanged water (70 parts) was added dropwise to the resulting liquid, and the dispersion beads were removed by filtration, thus obtaining a pigment dispersion with a solid pigment content of 11.6%. This pigment dispersion is designated as "DP 2".

[0163] <Preparation Example 3: Preparation of Pigment Dispersion DP3>

[0164] Joncyrl 68 (manufactured by BASF, mass average molecular weight: 13000) (9 parts) and triethanolamine (6 parts) were dissolved in deionized water (75 parts) and stirred for 1 hour. CI Pigment Blue 15:4 (manufactured by Daihisei Kagaku Co., Ltd., Chrom ofine Blue 4851) (30 parts) was added to the resulting solution, and the mixture was dispersed in a sand mill at 1500 rpm for 15 hours. Deionized water (40 parts) was added dropwise to the resulting liquid, and the dispersion beads were removed by filtration, thus obtaining a pigment dispersion with a solid content of 18.7%. The obtained pigment dispersion is designated as "DP3".

[0165] <Examples 1-13 and Comparative Examples 1-5>

[0166] The components listed in Tables 1-3 below were mixed and filtered using a membrane filter with a pore size of 3 μm to obtain the inks of Examples 1-13 and Comparative Examples 1-5. The values ​​in the component columns of Tables 1-3 indicate the amount (parts) of that component used; "-" indicates that the component was not used. Additionally, "-" in the surface tension column of Table 3 indicates that surface tension could not be measured due to ink incompatibility.

[0167] The abbreviations in Tables 1 to 3 below represent the following contents.

[0168] Dp1: Pigment dispersion obtained in Preparation Example 1

[0169] Dp2: Pigment dispersion obtained in Preparation Example 2

[0170] CABOJET: CAB-O-JET 400 (self-dispersing black pigment liquid, manufactured by Cabot Corporation, pigment solid content 15.1%)

[0171] Dp3: Pigment dispersion obtained in Preparation Example 3

[0172] 15PD: 1,5-Pentanediol (manufactured by Tokyo Chemical Industry Co., Ltd., boiling point: 242℃, logP value: -0.635, interfacial tension with OPP: 24.3 mN / m)

[0173] 14BD: 1,4-Butanediol (manufactured by Tokyo Chemical Industry Co., Ltd., boiling point: 230℃, log P value: -1.164, interfacial tension with OPP: 30.7 mN / m)

[0174] 3MB: 3-Methoxy-1-butanol (manufactured by Tokyo Chemical Industry Co., Ltd., boiling point: 158℃, logP value: 0.024, interfacial tension with OPP: 42.0 mN / m)

[0175] PNP: Propylene glycol n-propyl ether (manufactured by The Dow Chemical Company, boiling point: 149℃, logP value: 0.710, interfacial tension to OPP: 36.0 mN / m)

[0176] DEGBM: Diethylene glycol butyl methyl ether (manufactured by Tokyo Chemical Industry Co., Ltd., boiling point: 212℃, logP value: 1.188, interfacial tension with OPP: 23.9 mN / m)

[0177] 2EtHex13OH: 2-Ethylhexane-1,3-diol (manufactured by Tokyo Chemical Industry Co., Ltd., boiling point: 244℃, logP value: 1.258, interfacial tension with OPP: 17.1 mN / m)

[0178] BN3: BLAUNON BN-3 (polyoxyethylene β-naphthyl ether, manufactured by Aoki Oils & Fats Co., Ltd., interfacial tension with OPP: 7.4 mN / m)

[0179] EH3: Tergitol EH3 (polyoxyalkylene glycol 2-ethylhexyl ether, manufactured by The Dow Chemical Company, interfacial tension to OPP: 14.8 mN / m)

[0180] LA10: HITENOL LA-10 (polyoxyethylene lauryl ether ammonium sulfate, interfacial tension to OPP: 14.3 mN / m)

[0181] EP2544: GENAPOL EP2544 (polyoxyalkylene C12 / C15 alcohol, manufactured by Clariant Japan KK, interfacial tension to OPP: 14.3 mN / m)

[0182] Sf485: SURFYNOL 485 (acetylenic diol (C10) ethylene oxide adduct, manufactured by Evonik Industries AG, interfacial tension with OPP: 17.2 mN / m)

[0183] OD25: EMALEX OD-25 (polyoxyethylene octyl dodecyl ether, manufactured by Japan Emulsion Co., Ltd., interfacial tension to OPP: 20.7 mN / m)

[0184] Sf440: SURFYNOL 440 (acetylenic diol (C10) ethylene oxide adduct, manufactured by Evonik Industries AG)

[0185] [Table 1]

[0186]

[0187] [Table 2]

[0188]

[0189] [Table 3]

[0190]

[0191] <Evaluation>

[0192] [Compatibility Assessment]

[0193] Thirty portions of each ink from Examples 1-13 and Comparative Examples 1-5 were sealed in 50 mL Lab oran threaded vials (manufactured by ASONE Corporation, model 9-852-09). After standing at room temperature for at least 12 hours, the inks were visually inspected, and compatibility was evaluated according to the following evaluation criteria. The results are shown in Tables 4 and 5 below.

[0194] -Compatibility Evaluation Criteria-

[0195] A: A state of uniform and complete mixing

[0196] B: A state in which there are no oil droplets on the liquid surface, but the liquid is suspended and not completely dissolved.

[0197] C: The ink has droplets floating on its surface, indicating it is not completely dissolved.

[0198] D: The components in the ink are separated and completely insoluble.

[0199] [Contact Angle Measurement]

[0200] Using an OPP film (manufactured by Toyobo Co., Ltd., PYLEN Film-OT (P2102)) as the substrate, the contact angles between the inks obtained above and the OPP film were measured, and evaluated according to the following evaluation criteria. Specifically, a DM-501Hi (manufactured by Kyowa Interface Science Co., Ltd.) was used as a contact angle meter, with a droplet volume of 2 μL, and the contact angle was measured 10 seconds after the ink fell at 25°C. The results are shown in Tables 4 and 5 below. In Table 5, "-" indicates that the ink cannot be evaluated as an ink because the ink materials are not mixed.

[0201] -Contact Angle Evaluation Criteria-

[0202] A: Contact angle ≤18°

[0203] B: 18° < contact angle ≤ 21°

[0204] C: 21° < contact angle ≤ 23°

[0205] D: 23° < Contact Angle

[0206] [Table 4]

[0207]

[0208] [Table 5]

[0209]

[0210] As shown in Tables 4 and 5 above, compared with the inks of Comparative Examples 1 to 5, the inks of Examples 1 to 13 exhibit superior wettability on the OPP film and are also equivalent or better in terms of compatibility. These results indicate that the inks of Examples 1 to 13 are excellent inks that combine both wettability and compatibility.

Claims

1. Inkjet ink, which contains pigments, water-soluble organic solvents, and organic compounds (of which, Excluding the pigment and the water-soluble organic solvent) and water, The water content is 50-90% by mass relative to the total mass of the ink. The logP value of the water-soluble organic solvent is less than 1.

258. When the interfacial tension between the following mixture and the OPP (biaxially oriented polypropylene) membrane at 25°C is defined as the interfacial tension of the organic compound against the OPP membrane, the interfacial tension of the organic compound against the OPP membrane is less than 20.7 mN / m. The mixture is obtained by mixing 1 part by mass of the organic compound, 9 parts by mass of 1,4-butanediol, and 90 parts by mass of purified water. When the total mass of the water-soluble organic solvent contained in the inkjet ink is defined as (A) and the total mass of the organic compound is defined as (B), the value obtained by (B) / (A) is 0.01 to 0.

50. The surface tension of the ink for inkjet printing is less than 33.7 mN / m at 25°C. The water-soluble organic solvent accounts for 1 to 10% by mass relative to the total mass of the inkjet ink, and the organic compound accounts for 0.05 to 1.5% by mass. The organic compound comprises at least one selected from the group consisting of polyoxyalkylene alkyl ethers, polyoxyalkylene aryl ethers, and polyoxyethylene alkyl sulfates.

2. The ink for inkjet printing as described in claim 1, wherein, The interfacial tension of the organic compound against OPP is below 19 mN / m.

3. The ink for inkjet printing as described in claim 1, wherein, The interfacial tension of the organic compound against OPP is below 18 mN / m.

4. The ink for inkjet printing as described in any one of claims 1 to 3, wherein, The water-soluble organic solvent comprises at least one compound selected from the group consisting of a compound represented by formula (1) below, a compound represented by formula (2) below, propylene glycol alkyl ethers, and diethylene glycol alkyl ethers. [Chemical Formula 1] In equation (1), R 1 Represents a straight-chain or branched C4-C6 hydrocarbon group; [Chemical Formula 2] In equation (2), R 2 It represents a hydrogen atom or a methyl group.

5. The ink for inkjet printing as described in claim 4, wherein, The water-soluble organic solvent comprises at least one selected from the group consisting of 1,5-pentanediol, 1,4-butanediol, 1,6-hexanediol, propylene glycol monopropyl ether, diethylene glycol alkyl ether, and 3-methoxy-1-butanol.

6. The ink for inkjet printing as described in any one of claims 1 to 3, wherein, The organic compound comprises at least one selected from the group consisting of polyoxyethylene naphthyl ether, polyoxyalkylene-2-ethylhexyl ether, and polyoxyethylene lauryl sulfate.

7. An ink group comprising the inkjet ink according to any one of claims 1 to 6, and other inkjet inks different from the inkjet ink.

8. An ink media assembly comprising the ink for inkjet printing as described in any one of claims 1 to 6 or the ink assembly as described in claim 7, and a printing medium.

9. Printing media, of which, The inkjet ink of any one of claims 1 to 6, or each inkjet ink included in the ink group of claim 7, is attached.

Images