Inks, ink sets, ink media sets, and print media

Abstract

The present invention provides an ink which contains: a water-insoluble coloring agent that is selected from the group consisting of a pigment, a disperse dye and a solvent dye; a resin dispersant that has a weight average molecular weight of less than 50,000; a resin emulsion wherein the dissolution amount of the solid content in 100 g of methyl ethyl ketone at 25°C is 10 g or less; a sol that has an average particle diameter of 3 nm or more but less than 22 nm; and water. With respect to this ink, the content of the sol is from 1.0% by mass to 5.0% by mass. The present invention also provides: an ink set which comprises this ink; an ink medium set which comprises this ink or ink set, and a printing medium; and a printing medium to which this ink or each ink in the ink set adheres.

Description

[Technical Field]

[0001] The present invention relates to an ink, an ink set including the ink, an ink-media set including the ink or ink set and a printing medium, and a printing medium to which each ink included in the ink or ink set is adhered. [Background technology]

[0002] Among various color printing methods, printing using an inkjet printer (inkjet printing) is one of the most representative methods. This method generates small droplets of ink and deposits them on a printing medium such as paper to print. With advances in inkjet printing technology, inkjet printing has begun to be used in the field of high-resolution printing, which was previously achieved using silver halide photography and offset printing. In such fields, printing media that have low ink absorption, such as coated paper, are often used.

[0003] Furthermore, in recent years, the demand for industrial inkjet printing has increased, requiring new properties, one of which is the strong demand for improved abrasion resistance of the ink adhered to the printing media.

[0004] For example, if an inkjet printer prints on coated paper and the resulting print is rubbed with a fingernail or the like, the ink coating is pressed against the rubbed area only, smoothing the surface, resulting in stronger specular reflection of light and glare. The glare only in the rubbed area detracts from the overall appearance of the print, resulting in reduced print quality. Therefore, there is a strong demand for inks that minimize changes in the glare of the ink coating even when rubbed with a fingernail or the like.

[0005] Possible methods for suppressing glare in ink coatings include applying a pretreatment agent to coated paper before printing, or applying an overcoat agent to coated paper after printing. However, considering the need to reduce printing costs, improve printing speed, and increase the size of equipment due to additional processes, it is desirable to achieve the aforementioned abrasion resistance without using a pretreatment agent or overcoat agent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5273434 [Patent Document 2] Patent No. 4679322 [Patent Document 3] International Publication No. 2016 / 035787 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide an ink that causes little change in the glare of the ink coating even when a print obtained by printing on a printing medium with poor ink absorption, particularly offset coated paper, is scratched by a fingernail or the like; an ink set including the ink; an ink media set including the ink or ink set and a printing medium; and a printing medium to which the ink or each ink included in the ink set is attached. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following embodiments. 1) The present invention comprises: a water-insoluble colorant selected from the group consisting of pigments, disperse dyes, and solvent dyes; a resin dispersant having a weight-average molecular weight of less than 50,000; a resin emulsion having a solid content of 10 g or less dissolved in 100 g of methyl ethyl ketone at 25°C; a sol having an average particle size of 3 nm or more but less than 22 nm; and water; The ink has a content of the sol of 1.0 to 5.0% by mass.

[0009] 2) 1) The ink according to 1), wherein the sol contains at least one of a silica sol and a zirconium oxide sol.

[0010] 3) 2) The ink according to 2), wherein the sol includes silica sol.

[0011] 4) 3) The ink according to 3), wherein the sol contains at least one of a colloidal silica sol and an organosilica sol.

[0012] 5) The ink according to any one of items 1) to 4), wherein the resin emulsion contains at least one of an acrylic resin emulsion and an oxidized polyethylene wax emulsion.

[0013] 6) 5) The ink according to 5), wherein the resin emulsion comprises an acrylic resin emulsion and an oxidized polyethylene wax emulsion.

[0014] 7) The ink according to any one of items 1) to 6), wherein the content of the resin emulsion is 0.6 to 6.0 mass % in terms of solid content.

[0015] 8) The water-insoluble colorant has a BET specific surface area of ​​180 m 2 The ink according to any one of items 1) to 7), containing carbon black in an amount of 1 / g or more.

[0016] 9) An ink set comprising the ink according to any one of items 1) to 8) and another ink different from the ink.

[0017] 10) An ink-media set comprising the ink according to any one of items 1) to 8) or the ink set according to item 9), and a printing medium.

[0018] 11) A print medium to which the ink according to any one of items 1) to 8) or each ink included in the ink set according to item 9) is adhered. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide an ink that causes little change in the glare of the ink coating even when a print obtained by printing on a printing medium that is poorly ink-absorbent, in particular offset coated paper, is scratched by a fingernail or the like; an ink set comprising the ink; an ink media set comprising the ink or ink set and a printing medium; and a printing medium to which the ink or each ink comprised in the ink set is adhered. DETAILED DESCRIPTION OF THE INVENTION

[0020] Specific embodiments to which the present invention is applied will be described in detail below. As used herein, "CI" means "Color Index." In addition, in this specification, the terms "alkylene," "propylene," and "alkyl" are used to mean both straight-chain and branched-chain structures unless otherwise specified. In addition, in this specification, when a value in mass % is stated as a decimal point, the value is rounded to one decimal place and stated to one decimal place.

[0021] <Ink> The ink according to this embodiment contains a water-insoluble colorant selected from the group consisting of pigments, disperse dyes, and solvent dyes; a resin dispersant having a weight-average molecular weight of less than 50,000; a resin emulsion having a solid content of 10 g or less in 100 g of methyl ethyl ketone at 25°C; a sol having an average particle size of 3 nm or more but less than 22 nm; and water, wherein the content of the sol is 1.0 to 5.0 mass%.

[0022] The components contained in the ink according to this embodiment will be described in detail below. Note that each of the components described below may be used alone or in combination of two or more.

[0023] [Water-insoluble colorant] The term "water-insoluble colorant" refers to a colorant whose solubility in water at 25°C is usually 5 g / L or less, preferably 3 g / L or less, more preferably 1 g / L or less, and even more preferably 0.5 g / L or less. The lower limit of the solubility includes 0 g / L.

[0024] The water-insoluble colorant is selected from the group consisting of pigments, disperse dyes, and solvent dyes, and can be appropriately selected from known pigments, disperse dyes, and solvent dyes. Among these, pigments are preferred. Examples of pigments include inorganic pigments and organic pigments.

[0025] Examples of inorganic pigments include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides.

[0026] Examples of organic pigments include various pigments such as azo, disazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perinone, thioindigo, anthraquinone, and quinophthalone.

[0027] Specific examples of organic pigments include yellow pigments such as CI Pigment 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, 180, 185, 193, 199, 202, and 213; and CI Pigment Red Red pigments such as 5, 7, 12, 48, 48:1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 168, 177, 178, 179, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 269, and 272; blue pigments such as CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, and 80; violet pigments such as CI Pigment Violet 19, 23, 29, 37, 38, and 50; orange pigments such as CI Pigment Orange 13, 16, 43, 68, 69, 71, and 73; and CI Pigment Green green pigments such as CI Pigment Black 1; and the like.

[0028] As the disperse dye, for example, a dye selected from CI Dispers is preferred. Specific examples thereof include yellow dyes such as CI Dispers Yellow 9, 23, 33, 42, 49, 54, 58, 60, 64, 66, 71, 76, 79, 83, 86, 90, 93, 99, 114, 116, 119, 122, 126, 149, 160, 163, 165, 180, 183, 186, 198, 200, 211, 224, 226, 227, 231, and 237; red dyes such as CI Dispers Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, and 283; and CI Dispers Orange. Orange dyes such as 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, and 97; violet dyes such as CI Dispers Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, and 79:1; blue dyes such as CI Dispers Blue 27, 56, 60, 79:1, 87, 143, 165, 165:1, 165:2, 181, 185, 197, 202, 225, 257, 266, 267, 281, 341, 353, 354, 358, 364, 365, and 368; and the like.

[0029] As the solvent dye, for example, a dye selected from C1Solvent is preferred.

[0030] To adjust the color tone, two or more types of water-insoluble colorants can be blended. For example, in the case of black ink, it is preferable to use three to five types of water-insoluble colorants in combination, and in the case of color inks other than black ink, it is preferable to use two or more types of water-insoluble colorants in combination. However, when the black ink contains carbon black as the water-insoluble colorant, it is preferable to use two or one type of water-insoluble colorant. In this specification, color ink refers to colored inks other than black ink (for example, inks of colors such as yellow, magenta, cyan, red, orange, brown, violet, blue, and green).

[0031] The water-insoluble colorant contained in the black ink is preferably carbon black, such as thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, channel black, etc. Specific examples of carbon black include the Raven series manufactured by Columbia Carbon Corporation, the Monarch series, Regal series, and Mogul series manufactured by Cabot Corporation, the Printex series, Colour Black series, Special Black series, HIBLACK series, NIPex series, and NEROX series manufactured by Orion Engineered Carbons, 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.

[0032] Among these carbon blacks, carbon blacks with a BET specific surface area of ​​180 m are preferred from the viewpoint of improving print density on coated paper and plain paper. 2 / g or more is preferred, 2 / g or more is more preferable, and 260m 2Specific examples include Raven 2000, 2350ULTRA, 2500ULTRA, 2800ULTRA, 2900ULTRA, 3000ULTRA, 3500, and 5000ULTRA (all manufactured by Columbia Carbon Corporation); Monarch 700, 880, 900, 1000, and 1300 (all manufactured by Cabot Corporation); Printex 75, 80, 85, 95, and L6, Colour Black S160S, S170, FW18, FW182, FW1, FW2, FW171, FW200, and FW285, Special Black 5 and 6, HIBLACK 50L, 600L, 890, 930L, and 970LB, and NIPex 90, 160IQ, 170IQ, and 180IQ (all manufactured by Orion Engineered Carbons). The BET specific surface area of ​​carbon black can be measured in accordance with, for example, ASTM D 6556.

[0033] The DBP oil absorption of carbon black is preferably, for example, 40 to 150 mL / 100 g, and from the viewpoint of improving color development on plain paper, is preferably 70 mL / 100 g or more, and more preferably 90 mL / 100 g or more. The DBP oil absorption is the amount of DBP (dibutyl phthalate) absorbed by 100 g of carbon black per cm 3 It can be measured in accordance with JIS K 6221, for example.

[0034] The average particle size of the water-insoluble colorant is usually 50 to 250 nm, preferably 60 to 200 nm. In this specification, the average particle size refers to the average particle size of particles measured using a laser light scattering method.

[0035] The content of the water-insoluble colorant is usually 1 to 30 mass %, preferably 1 to 10 mass %, and more preferably 2 to 7 mass %, relative to the total mass of the ink according to this embodiment.

[0036] [Resin dispersant] Examples of resin dispersants include copolymers composed of at least two types of monomers (preferably at least one of which is a hydrophilic monomer) selected from the following monomers: styrene and its derivatives; vinylnaphthalene and its derivatives; aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids; (meth)acrylic acid and its derivatives; maleic acid and its derivatives; itaconic acid and its derivatives; phalic acid and its derivatives; vinyl acetate, vinyl alcohol, vinylpyrrolidone, acrylamide, and their derivatives.

[0037] Examples of such copolymers include styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, (meth)acrylic acid ester-(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)acrylic acid ester copolymers, (meth)acrylic acid ester-(meth)acrylic acid copolymers, and polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymers are preferred, with styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, and (meth)acrylic acid ester-(meth)acrylic acid copolymers being more preferred, (meth)acrylic acid ester-(meth)acrylic acid copolymers being even more preferred, and methacrylic acid ester-methacrylic acid copolymers being particularly preferred. Examples of copolymer types include block copolymers, random copolymers, and graft copolymers. These copolymers may be in the form of a salt.

[0038] In this specification, the term "(meth)acrylic" is used to mean both "acrylic" and "methacrylic." The same applies to "(meth)acrylate" and the like.

[0039] Resin dispersants can be synthesized or commercially available.

[0040] Examples of synthetic resin dispersants include the AB block polymer disclosed in WO 2013 / 115071. The monomer constituting the A block of the AB block polymer disclosed in WO 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, and more preferably a combination of these two monomers. Furthermore, the monomer constituting the B block of the AB block polymer disclosed in WO 2013 / 115071 is at least one monomer selected from benzyl methacrylate and benzyl acrylate, preferably benzyl methacrylate. Specific examples of AB block polymers include the block copolymers disclosed in Synthesis Examples 3 to 8 of WO 2013 / 115071.

[0041] Examples of commercially available resin dispersants include Joncyrl 62, 67, 68, 678, and 687 (styrene-acrylic copolymers manufactured by BASF); Movinyl S-100A (modified vinyl acetate copolymer manufactured by Japan Coating Resins Co., Ltd.); and Jurymer AT-210 (polyacrylic acid ester copolymer manufactured by Toa Gosei Co., Ltd.).

[0042] The weight-average molecular weight (MW) of the resin dispersant is less than 50,000, preferably 3,000 or more but less than 50,000, and more preferably 7,000 to 25,000. The weight-average molecular weight of the resin dispersant can be measured by gel permeation chromatography (GPC). Specifically, the measurement can be performed using a HLC-8320GPC (manufactured by Tosoh Corporation) as a GPC device, two TSK gel Super Multipore HZ-H columns (manufactured by Tosoh Corporation, inner diameter 4.6 mm × 15 cm), tetrahydrofuran as an eluent, and TSK Standard (manufactured by Tosoh Corporation) as a standard sample.

[0043] The acid value of the resin dispersant is, for example, preferably from 50 to 300 mgKOH / g, more preferably from 80 to 275 mgKOH / g, and even more preferably from 80 to 250 mgKOH / g.

[0044] The resin dispersant can be used in a state where it is mixed with a water-insoluble colorant, or the surface of the water-insoluble colorant can be partially or entirely coated with the resin dispersant, or both of these states can be used in combination.

[0045] The ratio of the total mass of the resin dispersant to the total mass of the water-insoluble colorant is usually 0.1 to 1.0, preferably 0.1 to 0.6, and more preferably 0.2 to 0.5.

[0046] [Resin emulsion] The resin emulsion contains a solid content (resin) that dissolves in an amount of 10 g or less in 100 g of methyl ethyl ketone at 25° C. The dissolution amount is preferably 8 g or less, more preferably 5 g or less, and even more preferably 2 g or less. A solid content (resin) that dissolves in an amount of 10 g or less in 100 g of methyl ethyl ketone at 25° C. typically has a weight average molecular weight of 50,000 or more.

[0047] The dissolution amount in this specification is measured as follows: The resin emulsion is completely dried in an environment of 35°C to obtain a solid content. The obtained solid content is then gradually added to 100 g of methyl ethyl ketone, and the upper limit at which complete dissolution can be confirmed visually is defined as the "dissolution amount."

[0048] The resin emulsion preferably contains at least one of a polymer emulsion and a wax emulsion.

[0049] Examples of polymer emulsions include emulsions obtained by dispersing polymers such as urethane-based, polyester-based, acrylic-based, vinyl acetate-based, vinyl chloride-based, styrene-acrylic-based, acrylic-silicone-based, and styrene-butadiene-based polymers in water or a water-soluble organic solvent. Among these, emulsions of polymers selected from urethane-based, acrylic-based, and styrene-butadiene-based polymers are preferred, and emulsions of acrylic polymers are more preferred.

[0050] Polymer emulsions can be synthesized or commercially available.

[0051] An example of a polymer emulsion obtained by synthesis is the polymer emulsion disclosed in WO 2015 / 147192. Among the polymers contained in the polymer emulsion disclosed in WO 2015 / 147192, a polymer obtained by polymerizing 0.5 to 3.5 parts by mass (preferably 1 to 3 parts by mass) of methacrylic acid, 41 to 59 parts by mass (preferably 42 to 58 parts by mass) of methyl methacrylate, 41 to 59 parts by mass (preferably 42 to 58 parts by mass) of 2-ethylhexyl acrylate, and 0.2 to 3 parts by mass (preferably 0.5 to 2 parts by mass) of methacrylic acid, without containing any other monomers, is preferred.

[0052] Commercially available polymer emulsions include, for example, Superflex 126, 130, 150, 170, 210, 420, 470, 820, 830, and 890 (urethane resin emulsions manufactured by Daiichi Kogyo Seiyaku Co., Ltd.); Hydran HW-350, HW-178, HW-163, HW-171, AP-20, AP-30, WLS-201, and WLS-210 (urethane resin emulsions manufactured by DIC Corporation); 0569, 0850Z, and 2108 (styrene-butadiene resin emulsions manufactured by JSR Corporation); AE980, AE981A, AE982, AE986B, and AE104 (acrylic resin emulsions manufactured by E-Tech Co., Ltd.); and NeoCryl A-1105, A-1125, A-1127 (all acrylic resin emulsions manufactured by Kusumoto Chemicals Co., Ltd.); and the like.

[0053] The wax emulsion may be an emulsion in which natural wax or synthetic wax is dispersed in water or a water-soluble organic solvent.

[0054] Examples of natural wax emulsions include emulsions of various waxes, such as petroleum-based waxes such as paraffin wax and microcrystalline wax; lignite-based waxes such as montan wax; vegetable waxes such as carnauba wax and candelilla wax; and animal and vegetable waxes such as beeswax and lanolin.

[0055] Examples of synthetic wax emulsions include emulsions of polyalkylene wax (preferably poly C2-C4 alkylene wax), oxidized polyalkylene wax (preferably oxidized poly C2-C4 alkylene wax), paraffin wax, etc. Among these, emulsions of wax selected from polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, and paraffin wax are preferred, and oxidized polyethylene wax emulsion is more preferred.

[0056] 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, and MINERPOL 221 (all manufactured by BYK); Mitsui Hiwax NL100, NL200, NL500, 4202E, 1105A, 2203A, NP550, NP055, and NP505 (all manufactured by Mitsui Chemicals, Inc.); KUE-100 and 11 (manufactured by Sanyo Chemical Industry Co., Ltd.); and HYTEC E-6500, 9015, and 6400 (manufactured by Toho Chemical Industry Co., Ltd.).

[0057] Among the above resin emulsions, it is preferable to include at least one of an acrylic resin emulsion and an oxidized polyethylene wax emulsion, and it is more preferable to include both.

[0058] The average particle size of the wax is preferably 50 nm to 5 μm, more preferably 100 nm to 1 μm, in order to prevent clogging of the inkjet head.

[0059] The solid content of the resin emulsion is typically 0.6 to 6.0 mass %, and preferably 1.0 to 5.0 mass %, relative to the total mass of the ink according to this embodiment, from the viewpoints of the fixation of the ink to paper, the ejection properties of the ink, and the storage stability of the ink.

[0060] [Zol] The sol is a liquid in which colloidal particles are dispersed. From the viewpoint of storage stability of the ink, the sol preferably contains at least one of silica sol and zirconium oxide sol. From the viewpoint of improving print density on coated paper and plain paper, the sol preferably contains silica sol, and more preferably contains at least one of colloidal silica sol and organosilica sol. In particular, in order to improve print density on coated paper and plain paper when used as a black ink, a sol having a BET specific surface area of ​​180 m 2It is preferable to combine carbon black having a surface area of ​​1 / g or more with colloidal silica sol.

[0061] The sol can be obtained as a commercially available product. Examples of commercially available colloidal silica sols include the Snowtex series manufactured by Nissan Chemical Industries, Ltd., the SI series manufactured by JGC Catalysts and Chemicals Co., Ltd., the Silicadol series manufactured by Nippon Chemical Industry Co., Ltd., and the PL series manufactured by Fuso Chemical Industry Co., Ltd. Examples of commercially available organosilica sols include methanol silica sol, IPA-ST, EG-ST, NPC-ST-30, PGM-ST, and NMP-ST manufactured by Nissan Chemical Industries, Ltd. Examples of commercially available zirconium oxide sols include the SZR series manufactured by Sakai Chemical Industry Co., Ltd.

[0062] The average particle size of the sol is 3 nm or more and less than 22 nm, preferably 5 to 20 nm, from the viewpoint of preventing scratches from being glaring.

[0063] The content of the sol is 1.0 to 5.0% by mass, and preferably 1.0 to 3.5% by mass, from the viewpoint of preventing scratches from becoming shiny and from the viewpoint of storage stability of the ink. [water] As the water, ion-exchanged water, distilled water, or the like having few impurities (metal ions, etc.) is preferred.

[0064] [Ink preparation agents] In addition to the components described above, the ink according to this embodiment may further contain ink preparation agents, such as organic solvents, surfactants, antifungal agents, preservatives, pH adjusters, rust inhibitors, and antifoaming agents.

[0065] (organic solvent) Examples of organic solvents include C1-C6 alkanols such as methanol, ethanol, propanol, texanol, isopropanol, butanol, isobutanol, secondary butanol, and tertiary butanol; carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-methylpyrrolidin-2-one; cyclic ureas such as 1,3-dimethylimidazolidin-2-one and 1,3-dimethylhexahydropyrimid-2-one; acetone, 2-methyl-2-hydroxypentanol, and the like. Ketones, ketoalcohols, or carbonates such as benzophenone-4-one and ethylene carbonate; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butylene glycol, 1,4-butylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol (preferably those having a molecular weight of 400, 800, 1540, or more), polypropylene glycol, thiodiglycol, mono-, oligo-, or polyalkylene glycols or thioglycols having a C2-C6 alkylene unit, such as glycol and dithiodiglycol; C3-C9 polyols (triols), such as glycerin, diglycerin, hexane-1,2,6-triol, and trimethylolpropane; glycol ethers, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether (preferably glycol ethers selected from C3-C10 mono-, di-, or triethylene glycol ethers, and C4-C13 mono-, di-, or tripropylene glycol ethers);Examples of suitable alkanediols include C5-C9 alkanediols such as 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, and 2,4-diethyl-1,5-pentanediol; γ-butyrolactone; and dimethyl sulfoxide. Among these, 1,2-hexanediol and Texanol are preferred.

[0066] (surfactant) Examples of surfactants include anionic, nonionic, silicone-based, and fluorine-based surfactants. Among these, surfactants selected from silicone-based and fluorine-based surfactants are preferred, and silicone-based surfactants are more preferred from the viewpoint of safety to living organisms and the environment.

[0067] Examples of anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acylamino acids or salts thereof, N-acylmethyl taurines, alkyl sulfates, polyoxyalkyl ether sulfates, alkyl sulfates, polyoxyethylene alkyl ether phosphates, rosin acid soaps, castor oil sulfates, lauryl alcohol sulfates, alkylphenol phosphates, alkyl phosphates, alkylaryl sulfonates, diethyl sulfosuccinates, diethylhexyl sulfosuccinates, and dioctyl sulfosuccinates.

[0068] Examples of nonionic surfactants include ether-based surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and polyoxyethylene distyrenated phenyl ether; ester-based surfactants such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; acetylene glycol (alcohol)-based surfactants such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyn-3-ol; and polyglycol ether-based surfactants. Examples of commercially available products include Surfynol 104, 104PG50, 82, 420, 440, 465, 485, and Olfin STG manufactured by Nissin Chemical Co., Ltd.; and Emulgen A-60, A-90, and A-500 manufactured by Kao Corporation.

[0069] Examples of silicone surfactants include polyether-modified siloxanes and polyether-modified polydimethylsiloxanes. Commercially available products include Dynol 960 and 980 manufactured by Air Products Co., Ltd., Silface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG009, and SAG010 manufactured by Nissin Chemical Co., Ltd., BYK-345, 347, 348, 349, 3455, LP-X23288, LP-X23289, and LP-X23347 manufactured by BYK, and TEGO Twin 4000 and TEGO Wet KL 245, 250, 260, 265, 270, and 280 manufactured by Evonic Tego Chemie.

[0070] Examples of fluorine-based surfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains.

[0071] (Anti-mold agent) Examples of antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof.

[0072] (preservatives) Examples of preservatives include organic sulfur compounds, organic nitrogen sulfur compounds, organic halogen compounds, haloaryl sulfone compounds, iodopropargyl compounds, haloalkylthio compounds, nitrile compounds, pyridine compounds, 8-oxyquinolines, benzothiazole compounds, isothiazolinone compounds, dithiols, pyridine oxide compounds, nitropropane compounds, organic tin compounds, phenol compounds, quaternary ammonium salt compounds, triazine compounds, thiazine compounds, anilides, adamantane compounds, dithiocarbamates, brominated indanone compounds, benzyl bromoacetate compounds, and inorganic salt compounds. Specific examples of organic halogen compounds include sodium pentachlorophenol. Specific examples of pyridine oxide compounds include sodium 2-pyridinethiol-1-oxide. Specific examples of isothiazoline 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, 2-methyl-4-isothiazolin-3-one calcium chloride, etc. Specific examples of other antiseptics and antifungals include anhydrous sodium acetate, sodium sorbate, sodium benzoate, and Proxel GXL(S), LV, and XL-2(S) manufactured by Lonza.

[0073] (pH adjuster) Examples of pH adjusters include alkanolamines such as diethanolamine, triethanolamine, and N-methyldiethanolamine; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide (aqueous ammonia); alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; and inorganic bases such as disodium phosphate.

[0074] (rust inhibitor) Examples of the rust inhibitor include acid sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

[0075] (Antifoaming agent) Examples of the antifoaming agent include silicone-based, silica mineral oil-based, olefin-based, and acetylene-based compounds. Commercially available products include Surfynol DF37, DF58, DF110D, DF220, MD-20, and Olefin SK-14 manufactured by Shin-Etsu Chemical Co., Ltd.

[0076] [Ink preparation method, etc.] The ink according to this embodiment can be prepared by preparing an aqueous dispersion containing a water-insoluble colorant and a resin dispersant, and then adding and mixing a resin emulsion, a sol, and, if necessary, ink preparation agents to this aqueous dispersion.

[0077] Examples of methods for preparing aqueous dispersions include phase inversion emulsification, acid precipitation, interfacial polymerization, in-situ polymerization, submerged hardening coating, coacervation (phase separation), submerged drying, melt-dispersion cooling, air suspension coating, spray drying, etc. Among these, phase inversion emulsification, acid precipitation, and interfacial polymerization are preferred, and phase inversion emulsification is more preferred.

[0078] When preparing an aqueous dispersion by phase inversion emulsification, for example, a resin 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 water-insoluble colorant is added to the resulting emulsion, and a dispersion treatment is performed. The organic solvent and a portion of the water are distilled off under reduced pressure from the resulting liquid to obtain the desired aqueous dispersion.

[0079] Dispersion treatment can be carried out using a sand mill (bead mill), roll mill, ball mill, paint shaker, ultrasonic disperser, microfluidizer, etc. For example, when using a sand mill, beads with a particle diameter of about 0.01 to 1 mm can be used, and the bead packing rate can be appropriately set to carry out dispersion treatment. The particle diameter of the particles contained in the aqueous dispersion can be made uniform by subjecting the aqueous dispersion obtained as described above to operations such as filtration and centrifugation. If foaming occurs during preparation of the aqueous dispersion, a trace amount of a known silicone-based, acetylene glycol-based, or other antifoaming agent can be added.

[0080] The average particle size (D50) of the water-insoluble colorant in the aqueous dispersion is usually 300 nm or less, preferably 30 to 280 nm, more preferably 40 to 270 nm, and even more preferably 50 to 250 nm. Similarly, D90 is usually 400 nm or less, preferably 350 nm or less, and more preferably 300 nm or less. The lower limit of D90 is preferably 100 nm or more. Similarly, D10 is usually 10 nm or more, preferably 20 nm or more, and more preferably 30 nm or more. The upper limit of D10 is preferably 100 nm or less. The average particle size of the water-insoluble colorant can be measured using laser light scattering.

[0081] When the ink according to this embodiment is used as an inkjet ink, it is preferable that the content of inorganic impurities, such as chlorides of metal cations (e.g., sodium chloride) and sulfates of metal cations (e.g., sodium sulfate), be low. Such inorganic impurities are often contained in commercially available water-insoluble colorants. The inorganic impurity content should be approximately 1% by mass or less of the total amount of the water-insoluble colorant, with the lower limit being below the detection limit of analytical instruments, i.e., 0%, being ideal. Methods for obtaining water-insoluble colorants with low inorganic impurities include, for example, a method using a reverse osmosis membrane; a method in which a solid water-insoluble colorant is suspended and stirred in a mixed solvent of water and a C1-C4 alcohol, such as methanol, followed by filtration and drying of the water-insoluble colorant; and a method in which inorganic impurities are exchanged and adsorbed using an ion exchange resin.

[0082] Furthermore, when the ink according to this embodiment is used as an inkjet ink, it is preferable to microfilter the ink. For microfiltration, a membrane filter, glass filter paper, or the like can be used. The pore size of the filter used for microfiltration is usually 0.5 to 20 μm, and preferably 0.5 to 10 μm.

[0083] The ink according to this embodiment can be used in various printing fields such as writing, printing, information printing, and textile printing, and is particularly preferably used in inkjet printing.

[0084] <Ink set, ink media set> The ink set according to this embodiment comprises the ink according to this embodiment described above and another ink different from the ink according to this embodiment. The other ink is not particularly limited as long as it has a different constitution from the ink according to this embodiment, but it is preferable that the other ink has a different hue from the ink according to this embodiment.

[0085] The ink set according to this embodiment includes the ink or ink set according to this embodiment described above and a print medium.

[0086] Examples of printing media include paper, film, fibers and cloth (cellulose, nylon, wool, etc.), leather, color filter substrates, etc. These recording media can be broadly divided into those with and without an ink-receiving layer.

[0087] Examples of recording media having an ink-receiving layer include those having a substrate such as paper, synthetic paper, or film on which an ink-receiving layer is provided. The ink-receiving layer can be provided by, for example, impregnating or coating the substrate with a cationic polymer; or by coating the substrate surface with inorganic fine particles such as porous silica, alumina sol, or special ceramics together with a hydrophilic polymer such as polyvinyl alcohol or polyvinylpyrrolidone. Such recording media are usually referred to as inkjet paper, inkjet film, glossy paper, or the like. Specific examples of commercially available products include, for example, Canon Inc.'s Professional Photo Paper, Super Photo Paper, Glossy Gold, and Matte Photo Paper; Seiko Epson Corporation's Crispia Photo Paper (High Gloss), Photo Paper (Glossy), and Photo Matte Paper; Hewlett-Packard Japan, Ltd.'s Advanced Photo Paper (Glossy); and Fujifilm Corporation's Painting Photo Finishing Pro.

[0088] On the other hand, examples of recording media that do not have an ink-receiving layer include various papers such as coated paper and art paper used for applications such as gravure printing and offset printing, cast coated paper used for label printing, etc. Specific examples of commercially available products include OK Top Coat+, a product name manufactured by Oji Paper Co., Ltd.

[0089] <Inkjet printing method> The inkjet printing method according to this embodiment is a method of printing by ejecting droplets of the ink according to this embodiment or each ink included in the ink set according to this embodiment in response to a print signal and depositing them onto a print medium. There are no particular restrictions on the ink nozzles of the inkjet printer that eject the ink, and they can be selected appropriately depending on the purpose.

[0090] Inkjet printing methods according to this embodiment also include methods for improving image quality by ejecting a large number of small volumes of inks each having a low content of water-insoluble colorant; methods for improving image quality by using a plurality of inks having substantially the same hue but different contents of water-insoluble colorant; and methods for improving the fixation of a water-insoluble colorant to a printing medium by using a colorless, transparent ink in combination with an ink containing a water-insoluble colorant.

[0091] As the inkjet printing method, known methods can be used, such as a charge control method, a drop-on-demand method (pressure pulse method), an acoustic inkjet method, and a thermal inkjet method.

[0092] When printing on a print medium, for example, a container containing ink (ink tank) is loaded into a predetermined position of an inkjet printer, and printing is performed on the print medium using the above printing method. Note that full-color printing can also be achieved by loading containers containing ink of each color into a predetermined position of the inkjet printer and printing on the print medium using the above printing method.

[0093] For all of the above, combinations of preferred items are more preferred, and combinations of more preferred items are 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. [Example]

[0094] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0095] In the examples, unless otherwise specified, "parts" means parts by mass, and "%" means % by mass. In the examples, all synthesis, preparation, and other operations were carried out under stirring unless otherwise specified. Furthermore, when quantification of the solid content of the colorant in the aqueous dispersion was required, it was calculated as a value converted to the colorant alone by the dry weight method using an MS-70 manufactured by A&D Co., Ltd.

[0096] <Preparation Example 1: Preparation of Dispersion DP1> The block copolymer of Synthesis Example 3 was prepared by following Synthesis Example 3 of WO 2013 / 115071. The acid value of the resulting block copolymer was 105 mgKOH / g and the weight-average molecular weight was 25,000. The resulting block copolymer (6.6 parts) was dissolved in 2-butanone (20 parts), and a solution of sodium hydroxide (0.36 parts) dissolved in ion-exchanged water (50 parts) was added thereto and stirred for 30 minutes to form an emulsion. Nerox 605 (carbon black manufactured by Orion Engineered Carbons) (20 parts) was added to the resulting emulsion, and dispersion treatment was carried out for 15 hours at 1,500 rpm using a sand grinder to obtain a liquid. Ion-exchanged water (120 parts) was added to the resulting liquid, and the dispersion beads were separated by filtration to obtain a filtrate. The 2-butanone and a portion of the water were distilled off from the resulting filtrate under reduced pressure using an evaporator to obtain dispersion DP1 with a colorant solids content of 12%.

[0097] <Preparation Example 2: Preparation of Dispersion DP2> Dispersion DP2 having a colorant solids content of 12% was obtained in the same manner as in Preparation Example 1, except that CI Pigment Yellow 74 (manufactured by Clariant, HANSA YELLOW 5GX01-JP) was used instead of Nerox 605.

[0098] <Preparation Example 3: Preparation of Resin Emulsion A> A liquid was obtained by adding water (100 parts), ammonium persulfate (0.3 parts), and a reactive emulsifier (1 part) to a glass reaction vessel (volume 3 L). The air inside the reaction vessel was replaced with nitrogen, and the temperature of the liquid was raised to 70°C. A liquid consisting of water (120 parts), a reactive emulsifier (0.9 parts), methacrylic acid (2 parts), methyl methacrylate (37 parts), 2-ethylhexyl acrylate (59 parts), and allyl methacrylate (2 parts) was added dropwise to the liquid over a period of 3 hours. During the dropwise addition, the liquid temperature was maintained at 70°C while nitrogen was introduced, and the reaction was carried out. After the dropwise addition was completed, the reaction was continued for another 2 hours at 70°C and then cooled to 40°C. Triethanolamine (3.1 parts) was added to the resulting liquid to obtain Resin Emulsion A as a white suspension with a solids content of 25%. The amount of solids (resin) contained in Resin Emulsion A that dissolved in 100 g of methyl ethyl ketone at 25°C was 5 g or less, the acid value was 13 mg KOH / g, and the glass transition temperature (Tg) was -10°C.

[0099] <Examples 1 to 15: Preparation of ink> The components shown in Tables 1 and 2 below were mixed and then filtered through a membrane filter with a pore size of 3 μm to obtain inks of Examples 1 to 15, respectively.

[0100] <Comparative Examples 1 to 6: Preparation of Inks for Comparison> The components listed in Table 3 below were mixed and then filtered through a membrane filter with a pore size of 3 μm to obtain inks of Comparative Examples 1 to 6. The ink of Comparative Example 5 had extremely poor storage stability, and could not be evaluated for rub resistance, etc., as described below.

[0101] The abbreviations in Tables 1 to 3 have the following meanings. 12HD: 1,2-hexanediol PG: 1,2-propanediol TEX: Texanol TEA: Triethanolamine BYK349: BYK, BYK-349 Resin emulsion B: BYK AQUACER 515 (solid content: 35%, solubility of solid content in 100 g of methyl ethyl ketone at 25°C: 1 g or less) ST30: Snowtex 30 (colloidal silica sol, solid content: 30%), manufactured by Nissan Chemical Co., Ltd. STXS: Snowtex XS (colloidal silica sol, solid content: 20%), manufactured by Nissan Chemical Co., Ltd. STC: Snowtex C (colloidal silica sol, solid content: 20%), manufactured by Nissan Chemical Co., Ltd. SD40: Silicadol 40 (colloidal silica sol, solid content: 40%), manufactured by Nippon Chemical Industry Co., Ltd. SZRCW: Sakai Chemical Industry Co., Ltd., SZR-CW (zirconium oxide sol, solid content: 30%) SZRGCW: SZR-GCW (zirconium oxide sol, solid content: 30%), manufactured by Sakai Chemical Industry Co., Ltd. PGMST: Nissan Chemical Co., Ltd., PGM-ST (organosilica sol, solid content: 30%) ST50T: Snowtex 50T (colloidal silica sol, solid content: 50%), manufactured by Nissan Chemical Co., Ltd. ST30L: Snowtex 30L (colloidal silica sol, solid content: 30%), manufactured by Nissan Chemical Co., Ltd. GXL(S): Proxel GXL(S), manufactured by Lonza

[0102] [Table 1]

[0103] [Table 2]

[0104] [Table 3]

[0105] <Evaluation> [Evaluation of abrasion resistance] Using each of the inks of Examples 1 to 15 and Comparative Examples 1 to 4 and 6, inkjet printing was performed on printing media using a single pass (1 pass) method, resulting in a 100% duty printed image. The printing media used was offset coated paper "OK ​​Topcoat+" manufactured by Oji Paper Co., Ltd. The inkjet head used was a 600 dpi head manufactured by Kyocera Corporation, and the head temperature was set to 32°C. The amount of ink droplets ejected was 12 pL. After inkjet printing, the resulting printed image was dried.

[0106] The dried printed image was scratched with a fingernail, and the printed image was held up to a fluorescent lamp to observe the difference in glare between the scratched area and other areas, and the scratch resistance was evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 4 and 5 below. -Evaluation criteria- A: All 10 observers judged that there was no glare or change in gloss in the rubbed area. B: All 10 observers judged that "there was a glitter or change in gloss in the rubbed area." C: When rubbing the line, the ink in the rubbed area peeled off from the paper, and no difference in glare could be observed.

[0107] [Table 4]

[0108] [Table 5]

[0109] As shown in Tables 4 and 5, the prints obtained using each of the inks of the Examples had excellent abrasion resistance, with little change in the glare of the ink coating, even when scratched with a fingernail on offset coated paper.

[0110] [Print density evaluation] Using each of the inks of Examples 1 to 6, 13 to 15, and Comparative Examples 1 to 4 and 6, inkjet printing was performed on printing media using a single pass (1 pass) method, resulting in a 100% duty printed image. The printing media used were offset coated paper "OK ​​Topcoat+" manufactured by Oji Paper Co., Ltd. and plain paper "Npi Form 70NEXT-IL" manufactured by Nippon Paper Industries Co., Ltd. The inkjet head used was a 600 dpi head manufactured by Kyocera Corporation, and the head temperature was set to 32°C. The amount of ink droplets ejected was 12 pL. After inkjet printing, the resulting printed image was dried.

[0111] The dried printed image was measured using a spectrophotometer (eXact, manufactured by X-Rite). The colorimetry was performed under the following conditions: density standard: ANSI T, light source: D65, and viewing angle: 2°. The print density was evaluated according to the evaluation criteria shown in Table 6 below. The results are shown in Table 7 below.

[0112] [Table 6]

[0113] [Table 7]

[0114] As shown in Table 7, with each of the inks of the examples, good print density was achieved when printing on both offset coated paper and plain paper.

[0115] <Preparation Example 4: Preparation of Dispersion DP3> The block copolymer of Synthesis Example 3 was prepared by following Synthesis Example 3 of WO 2013 / 115071. The acid value of the resulting block copolymer was 105 mgKOH / g and the weight-average molecular weight was 25,000. The resulting block copolymer (6.6 parts) was dissolved in 2-butanone (20 parts), and a solution of sodium hydroxide (0.36 parts) dissolved in ion-exchanged water (50 parts) was added thereto and stirred for 30 minutes to form an emulsion. HIBLACK 890 (carbon black manufactured by Orion Engineered Carbons) (20 parts) was added to the resulting emulsion, and dispersion treatment was carried out for 15 hours at 1,500 rpm using a sand grinder to obtain a liquid. Ion-exchanged water (120 parts) was added to the resulting liquid, and the dispersion beads were separated by filtration to obtain a filtrate. The 2-butanone and a portion of the water were distilled off from the resulting filtrate under reduced pressure using an evaporator to obtain dispersion DP3 with a colorant solids content of 12%.

[0116] <Preparation Example 5: Preparation of Dispersion DP4> A dispersion DP4 having a colorant solids content of 12% was obtained in the same manner as in Preparation Example 4, except that NIPex90 (carbon black manufactured by Orion Engineered Carbons) was used instead of HIBLACK890.

[0117] <Preparation Example 6: Preparation of Dispersion DP5> Dispersion liquid DP5 having a colorant solids content of 12% was obtained in the same manner as in Preparation Example 4, except that Printex 80 (carbon black manufactured by Orion Engineered Carbons) was used instead of HIBLACK 890.

[0118] <Preparation Example 7: Preparation of Dispersion DP6> Dispersion liquid DP6 having a colorant solids content of 12% was obtained in the same manner as in Preparation Example 4, except that HIBLACK50L (carbon black manufactured by Orion Engineered Carbons) was used instead of HIBLACK890.

[0119] The physical properties of the carbon black used in Preparation Examples 4 to 7 above are shown in Table 8 below.

[0120] [Table 8]

[0121] <Examples 16 to 25: Preparation of ink> The components shown in Tables 9 and 10 below were mixed and then filtered through a membrane filter with a pore size of 3 μm to obtain inks of Examples 16 to 25, respectively.

[0122] Comparative Examples 7 to 11: Preparation of Inks for Comparison The components shown in Table 11 below were mixed and then filtered through a membrane filter with a pore size of 3 μm to obtain inks of Comparative Examples 7 to 11, respectively.

[0123] The abbreviations in Tables 9 to 11 have the following meanings. 12HD: 1,2-hexanediol PG: 1,2-propanediol TEX: Texanol TEA: Triethanolamine BYK349: BYK, BYK-349 Resin emulsion C: NeoCryl A-1127 manufactured by Kusumoto Chemicals Co., Ltd. (solid content: 44%, solubility of solid content in 100 g of methyl ethyl ketone at 25°C: 1 g or less) Resin emulsion D: BYK AQUACER 531 (solid content: 45%, solubility of solid content in 100 g of methyl ethyl ketone at 25°C: 5 g or less) ST30: Snowtex 30 (colloidal silica sol, solid content: 30%), manufactured by Nissan Chemical Co., Ltd. STXS: Snowtex XS (colloidal silica sol, solid content: 20%), manufactured by Nissan Chemical Co., Ltd. SD40: Silicadol 40 (colloidal silica sol, solid content: 40%), manufactured by Nippon Chemical Industry Co., Ltd. ST50T: Snowtex 50T (colloidal silica sol, solid content: 50%), manufactured by Nissan Chemical Co., Ltd. ST30L: Snowtex 30L (colloidal silica sol, solid content: 30%), manufactured by Nissan Chemical Co., Ltd. SZRCW: Sakai Chemical Industry Co., Ltd., SZR-CW (zirconium oxide sol, solid content: 30%) SZRGCW: SZR-GCW (zirconium oxide sol, solid content: 30%), manufactured by Sakai Chemical Industry Co., Ltd. PGMST: Nissan Chemical Co., Ltd., PGM-ST (organosilica sol, solid content: 30%) GXL(S): Proxel GXL(S), manufactured by Lonza

[0124] [Table 9]

[0125] [Table 10]

[0126] [Table 11]

[0127] <Evaluation> [Print density evaluation] Using a bar coater No. 3 (Yasuda Machinery Works, Ltd.), each of the inks of Examples 11 to 25 and Comparative Examples 7 to 11 was applied to a printing medium. The printing media used were offset coated paper "OK ​​Top Coat+" manufactured by Oji Paper Co., Ltd. and plain paper "Npi Form 70NEXT-IL" manufactured by Nippon Paper Industries Co., Ltd. The resulting image was dried at 70°C for 2 minutes to obtain a test specimen.

[0128] The optical density (OD value) of the obtained test piece was measured at five points using a spectrophotometer (eXact, manufactured by X-Rite), and the average value was used as the OD value of the test piece. Colorimetry was performed under the following conditions: density standard: ANSI T, light source: D65, and viewing angle: 2°. The print density was then evaluated according to the following evaluation criteria. The results are shown in Table 12 below. -Evaluation criteria (OK top coat +)- A:OD value is 2.3 or more B: OD value is 2.0 or more and less than 2.3 C:OD value is 1.7 or more and less than 2.0 D:OD value is less than 1.7 -Evaluation Criteria (Npi Form 70NEXT-IJ)- A:OD value is 1.30 or more B: OD value is 1.25 or more and less than 1.30 C:OD value is 1.20 or more and less than 1.25 D:OD value is less than 1.20

[0129] [Table 12]

[0130] As shown in Table 12, with each of the inks of the examples, good print density was achieved when printing on both offset coated paper and plain paper.

Claims

1. a water-insoluble colorant selected from the group consisting of pigments, disperse dyes, and solvent dyes; a resin dispersant having a weight-average molecular weight of less than 50,000; a resin emulsion having a solubility of 10 g or less of solid content in 100 g of methyl ethyl ketone at 25°C; a sol having an average particle size of 3 nm or more and less than 22 nm; and water, wherein the resin emulsion contains an acrylic resin emulsion and an oxidized polyethylene wax emulsion; The ink has a content of the sol of 1.0 to 5.0% by mass.

2. The ink of claim 1 , wherein the sol comprises at least one of a silica sol and a zirconium oxide sol.

3. The ink of claim 2 , wherein the sol comprises a silica sol.

4. The ink according to claim 3 , wherein the sol comprises at least one of a colloidal silica sol and an organosilica sol.

5. 5. The ink according to claim 1, wherein the content of the resin emulsion is 0.6 to 6.0 mass % in terms of solid content.

6. The water-insoluble colorant has a BET specific surface area of ​​180 m ２ The ink according to any one of claims 1 to 5, comprising carbon black in an amount of 1 / g or more.

7. An ink set comprising the ink according to any one of claims 1 to 6 and another ink different from said ink.

8. An ink-media set comprising the ink according to any one of claims 1 to 6 or the ink set according to claim 7, and a printing medium.

9. A printing medium to which the ink according to any one of claims 1 to 6 or each of the inks included in the ink set according to claim 7 is adhered.

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