Ink, and inkjet recording method

Abstract

To provide an ink that enables the provision of printed matter having no uneven coating and an excellent scratch resistance, an inkjet recording method using the ink, and a recording media having the ink adhered.SOLUTION: Provided is an ink that contains a water-insoluble colorant, a dispersant, water, a nonionic surfactant having a HLB value of more than 7.9 and 20.0 or less, and a resin having a weight average molecular weight of 4500 to 500,000. Here, if the nonionic surfactant and the resin having a weight average molecular weight of 4500 to 500,000 are both siloxane compound, they cannot be the same compound.SELECTED DRAWING: None

Description

Technical Field

[0001] An object of the present invention is to provide an ink, an inkjet recording method using the ink, and a recording medium colored with the ink.

Background Art

[0002] Among various color recording methods, a recording method using an inkjet printer, which is one of the representative methods, generates small droplets of ink and attaches them to a recording medium such as paper to perform recording. In recent years, the demand for industrial applications has increased, and it is required to cope with various recording media.

[0003] In particular, for ink non-absorbent media typified by films (hereinafter sometimes referred to as "non-absorbent media"), the development of solvent inks mainly composed of organic solvents and UV inks containing polymerizable monomers has been promoted. However, these inks have many safety problems such as VOCs and skin sensitization, and their applications are limited.

[0004] Therefore, at present, as described in Patent Documents 1 and 2, the development of water-based inks capable of printing images with high durability on non-absorbent media by adding polymer fine particles while mainly using water has been actively carried out.

[0005] However, even when using the inks obtained by these proposals, the rub resistance against non-absorbent media such as PET (polyethylene terephthalate) and PP (polypropylene) is insufficient, and improvement is required.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide an ink that enables the provision of a printed matter excellent in the balance between coating unevenness and rubbing resistance, an inkjet recording method using the ink, and a recording medium to which the ink adheres.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above-described problems, the present inventors have found that the above problems can be solved by the ink, recording medium, and recording method described in the following [1] to [5], and have completed the present invention.

[0009] That is, the present invention relates to the following [1] to [5]. [1] An ink containing a water-insoluble colorant, a dispersant, water, a nonionic surfactant having an HLB value greater than 7.9 and not more than 20.0, and a resin having a weight average molecular weight of 4,500 to 500,000, provided that when both the nonionic surfactant and the resin having a weight average molecular weight of 4,500 to 500,000 are siloxane compounds, they are not the same compound. [2] The ink according to [1], further containing glycol ethers. [3] The ink according to [2], wherein the glycol ethers are alkylene glycol monoalkyl ethers. [4] A recording medium to which the ink according to any one of [1] to [3] adheres. [5] An inkjet recording method of performing recording by ejecting droplets of the ink according to any one of [1] to [3] from an inkjet printer and attaching them to a recording medium.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide an ink that enables the provision of a printed matter excellent in the balance between coating unevenness and rubbing resistance, an inkjet recording method using the ink, and a recording medium colored with the ink.

Embodiment for Carrying Out the Invention

[0011] [Water-insoluble colorant] The above colorant is not particularly limited as long as it is a water-insoluble colorant. For example, known pigments, disperse dyes, solvent dyes, etc. can be used. In this specification, the water-insoluble colorant means a colorant having a solubility of usually 5 g or less, preferably 3 g or less, more preferably 1 g or less, and still more preferably 0.5 g or less in 1 liter of water at 25°C. The lower limit of the solubility includes 0 g. Unless otherwise specified, the "water-insoluble colorant" is hereinafter referred to as "colorant". Colorants can be used in combination. The number of types of colorants contained in the above ink is usually 3 or more. When it is black ink, 3 to 5 types are preferable. When it is a color ink other than black ink, it is usually 3 types, preferably 2 types, or 1 type. However, when the black ink contains carbon black as a colorant, the number of types of colorants is preferably 2 types or 1 type. In this specification, the color ink means a colored ink other than black ink (for example, inks of various colors such as yellow, magenta, cyan, red, orange, brown, violet, blue, green, etc.). Among pigments, disperse dyes, and solvent dyes, pigments are preferable. Examples of pigments include inorganic pigments, organic pigments, and extender pigments.

[0012] Examples of inorganic pigments include carbon black, titanium oxide, metal oxides, hydroxides, sulfides, ferrocyanides, and metal chlorides.

[0013] As the colorant contained in the black ink, carbon blacks such as thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black are preferable. Specific examples of carbon black include, for example, the Raven series manufactured by Columbian Carbon; the Monarch series, Regal series, and Mogul series manufactured by Cabot; the ColorBlack series, Printex series, SpecialBlack series, and Nerox series manufactured by Orion Engineered Carbons; the MA series, MCF series, No. 25, No. 33, No. 40, No. 47, No. 52, No. 900, and No. 2300 manufactured by Mitsubishi Chemical, etc.

[0014] Examples of organic pigments include various pigments such as azo, diazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perinone, thioindigo, anthraquinone, and quinophthalone.

[0015] Specific examples of organic pigments include, for example, yellows such as C.I. 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, 155, 180, 185, 193, 199, 202, 213; C.I. Pigment Red 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 , reds such as 272; blues such as C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, 80; violets such as C.I. Pigment Violet 19, 23, 29, 37, 38, 50; oranges such as C.I. Pigment Orange 13, 16, 68, 69, 71, 73; greens such as C.I. Pigment Green 7, 36, 54; blacks such as C.I. Pigment Black 1 and other colored pigments can be mentioned.

[0016] Examples of extender pigments include silica, calcium carbonate, talc, clay, barium sulfate, and white carbon. Extender pigments are often used in combination with other colorants.

[0017] Examples of the disperse dyes include known disperse dyes. Among them, dyes selected from C.I. Disperse are preferred. Specific examples thereof include, for example, C.I. Disperse 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, 237, etc. of yellow; C.I. Disperse Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, 283, etc. of red; C.I. Disperse Orange 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, 97, etc. of orange; C.I. Disperse Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, 79:1, etc. of violet; C.I. Disperse 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, 368, etc. of blue disperse dyes of various colors.

[0018] The content of the colorant relative to the total mass of the above ink is usually 1 to 30%, preferably 1 to 10%, more preferably 2 to 7%. In addition, the average particle size of the colorant is usually 50 nm to 250 nm, preferably 60 nm to 200 nm. In this specification, the average particle size refers to the average particle size of the particles measured using the laser light scattering method.

[0019] [Dispersant] The above dispersant is not particularly limited, and known dispersants can be used. The dispersant is used for the purpose of dispersing a water-insoluble colorant in the ink. Generally, polymer dispersants such as resins are used as the dispersant. Examples of such resins include polyvinyl alcohol, cellulose derivatives, polyethylene oxide, polypropylene oxide, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, sulfoethyl methacrylate, sulfopropyl methacrylate, ionic monomers such as α,β-unsaturated monomers of sulfonated vinyl naphthalene, styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids, acrylonitrile, vinylidene chloride, vinyl acetate, vinyl chloride, acrylamide, methacrylamide, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, polymers derived from N-butoxymethylacrylamide, and the like.

[0020] Examples of the above dispersant include the A-B block polymer disclosed in International Publication No. 2013 / 115071 Gazette, and the same ones including preferred ones. The same also applies to the production method of the A-B block polymer and the like. As an example of the dispersant (A-B block polymer) disclosed in International Publication No. 2013 / 115071 Gazette, for example, the monomer constituting the above A polymer is one or more monomers selected from (meth)acrylic acid and linear or branched C4 alkyl (meth)acrylate, and the monomer constituting the B polymer is benzyl methacrylate and / or benzyl acrylate. In this specification, the terms “(meth)acrylic” and “(meth)acrylate” are used to mean including both “acrylic, methacrylic” and “acrylate, methacrylate”. The monomers constituting block A are preferably one or more monomers selected from methacrylic acid and n-butyl methacrylate, and it is particularly preferable to use these two monomers in combination. The monomer constituting block B is preferably benzyl methacrylate. Specific examples thereof include the block copolymers disclosed in Synthesis Examples 3 to 8 of the above-mentioned International Publication Gazette.

[0021] As the styrene-(meth)acrylic polymer, the Joncryl series manufactured by BASF is preferable.

[0022] The acid value of the dispersant is usually 90 to 200 mgKOH / g, preferably 100 to 150 mgKOH / g, more preferably 100 to 120 mgKOH / g. The mass average molecular weight of the dispersant is usually 10,000 to 60,000, preferably 10,000 to 40,000, more preferably 15,000 to 30,000, and even more preferably 20,000 to 25,000. The PDI (mass average molecular weight / number average molecular weight) of the dispersant is about 1.29 to 1.49. By setting it within the above range, good dispersibility and storage stability can be achieved. Examples of the neutralizing agent include ammonia, alkali metal hydroxides, alkaline earth metal hydroxides, aliphatic amine compounds, and alkanolamine compounds. Ammonia and alkali metal hydroxides are preferable, and ammonia is particularly preferable. The amount of the neutralizing agent used is not particularly limited. As a guide, when neutralized with the theoretical equivalent amount of the acid value of the dispersant as 100% neutralization degree, it is usually 30 to 300% neutralization degree, more preferably 50 to 200% neutralization degree.

[0023] The above dispersant can be used in a state of being mixed with a water-insoluble colorant. Further, it can also be used in a state where the surface of the water-insoluble colorant is coated with the dispersant. Further, both of these can be used in combination. In this specification, "coating" means both a state where the entire surface of the water-insoluble colorant is covered with the dispersant and a state where a part of the surface of the water-insoluble colorant is covered with the dispersant. When using the dispersant, the ratio of the total mass of the dispersant to the total mass of the water-insoluble colorant is usually 0.1 to 1.0, preferably 0.1 to 0.6, more preferably 0.2 to 0.5.

[0024] [Nonionic surfactant with an HLB value greater than 7.9 and less than or equal to 20.0] As the above nonionic surfactant with an HLB value greater than 7.9 and less than or equal to 20.0, there is no particular limitation as long as it is a nonionic surfactant with an HLB value greater than 7.9 and less than or equal to 20.0. For example, the "general-purpose nonionic surfactant", "silicone-based nonionic surfactant", and "fluorine-based nonionic surfactant" described later can be mentioned. Compared with ionic surfactants, nonionic surfactants are less likely to cause intermolecular interactions such as ionic bonds and are likely to lower the surface tension. Therefore, they are easily wetted on the medium and are less likely to cause coating unevenness in printed matter.

[0025] Examples of the above “general nonionic surfactant” include polyoxyalkylene alkyl ethers such as polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene tridecyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and polyoxyethylene alkyl ether; polyoxyalkylene acylates such as polyoxyethylene oleic acid ester, polyoxyethylene distearic acid ester, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; polyoxyethylene aryl ethers such as polyoxyalkylene styrenated phenyl ether; acetylene glycol (alcohol) - based compounds 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 - hexyne - 3 - ol; and polyglycol ether - based compounds. Nonionic surfactants can be obtained, for example, as the Surfynol series such as Surfynol 465 of Nissin Chemical Co., Ltd., the Orfin series, the Emulgen series of Kao Corporation, the Newcol series of Nippon Emulsion Co., Ltd. (e.g., Newcol NT - 5 and 12 which are polyoxyethylene alkyl ethers), and the Neugen series of Daiichi Kogyo Seiyaku Co., Ltd. (e.g., Neugen TDX - 50 which is polyoxyalkylene tridecyl ether, Neugen EA197D which is polyoxyethylene styrenated phenyl ether, etc.). They can be obtained as, for example, the Surfynol series such as Surfynol 465 of Nissin Chemical Co., Ltd., the Orfin series, the Emulgen series of Kao Corporation, the Newcol series of Nippon Emulsion Co., Ltd. (e.g., Newcol NT - 5 and 12 which are polyoxyethylene alkyl ethers), and the Neugen series of Daiichi Kogyo Seiyaku Co., Ltd. (e.g., Neugen TDX - 50 which is polyoxyalkylene tridecyl ether, Neugen EA197D which is polyoxyethylene styrenated phenyl ether, etc.).

[0026] Examples of the above-mentioned "silicone-based nonionic surfactant" include siloxane compounds such as polyether-modified siloxane and polyether-modified polydimethylsiloxane. Examples thereof include Dynol 960 and Dynol 980 manufactured by Air Products, Silface SAG001, Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG503A, Silface SAG008, Silface SAG009, Silface SAG010 manufactured by Nisshin Chemical Co., Ltd., and BYK-345, BYK-347, BYK-348, BYK-349, BYK-3455, BYK-LP-X23288, BYK-3451 (alias: BYKLPX 23347), BYK-3450 (alias: BYKLPX 23289) manufactured by BYK-Chemie, etc., and they are available for purchase.

[0027] Examples of the above-mentioned "fluorine-based nonionic surfactant" include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid-based compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain, etc. Fluorine-based surfactants can be obtained from, for example, Chemours, DuPont, Omnova, DIC Corporation, and BYK-Chemie, etc. Specific examples thereof include Capstone FS-30 manufactured by Chemours, etc.

[0028] The HLB value of the above nonionic surfactant is greater than 7.9 and less than or equal to 20.0, preferably 8.0 to 18.0, more preferably 9.0 to 18.0. In this specification, the HLB value is rounded to the first decimal place after rounding the second decimal place. Also, it can be obtained as an actual measurement value through experiments. As for the method, known methods can be used. As an example, for instance, the method according to the Griffin method described in International Publication No. WO2017 / 159685 can be mentioned. The HLB value can be calculated by the following formula (1). Note that the "HLB value" described in this specification means the HLB value calculated using the above-mentioned Griffin method when the structure of the compound to be used is clearly known. HLB value = 20 × (sum of molecular weights of hydrophilic moieties) ÷ (molecular weight of the material) Formula (1) Also, when the HLB value is described in the catalogs of the manufacturer or the seller, etc., that numerical value can also be used. When the above HLB value has no decimal places, the first decimal place is regarded as "zero" and the value is described up to the first decimal place.

[0029] [Resin with a weight average molecular weight of 4500 to 500000] Generally, the role of the resin used in aqueous inkjet inks is to be used for the purpose of imparting adhesion to the substrate and resistance to the printed surface. The structures of the resins used include acrylic, styrene-acrylic, urethane, olefin, paraffin, etc., which are diverse. In common, the higher the molecular weight of these resins, the higher the strength of the formed film. The strength of the film is derived from the glass transition point of the resin, which is due to the increase in the glass transition point of the resin as the molecular weight increases. Therefore, the higher the molecular weight of the resin used, the higher the strength of the printed surface. Examples of resins with a weight average molecular weight of 4500 to 500000 include Ebafarl HA-15 manufactured by Nikkawa Chemical Co., Ltd. and NeoCryl A-655 manufactured by DSM Coating Resin. The weight average molecular weight of the resin is preferably 5000 to 400000, more preferably 6500 to 300000. Also, as an example of the resin, the siloxane compound described later is also included.

[0030] [Siloxane compound] Siloxane is a compound with a silicon-oxygen backbone and is known as a general term for those having Si-O-Si bonds. As the above siloxane compound, a compound having a siloxane structure that exhibits the property of improving the slipperiness of the coating film surface corresponds. Also, the reason why those with a long siloxane backbone in the main chain are considered effective is the influence on film formation on the ink surface. When the siloxane backbone in the main chain becomes longer, the hydrophobicity increases, and the siloxane compound floats on the surface after the ink dries, forming a microfilm. Since this microfilm acts as a so-called lubricant, it is considered that the friction coefficient decreases and slipperiness appears. Siloxane compounds with a short siloxane backbone and a molecular weight lower than 4500 have a weak linearity of siloxane bonds and are prone to hydrogen bonding, so their hydrophobic performance is weak. Therefore, it is said that slipperiness is difficult to exhibit. Examples of siloxane compounds include dimethylsiloxane, methylsiloxane, and silanol. Among them, dimethylsiloxane has high hydrophobicity and is likely to form a silicon film on the ink surface during the drying process, so it exhibits more slipperiness. The silicone-based surfactant described above has a short main chain and does not exhibit a slip effect, so the difference from this siloxane compound is explained by the weight average molecular weight. Examples of such siloxane compounds include BYK-3760 manufactured by BYK Chemie, TEGO Glide 490 manufactured by Evonik, and DOWSIL IE-7170 manufactured by Toray Dow Corning. As the siloxane compound, a compound having a weight average molecular weight in this range is preferred. By containing such a compound in the above ink, a printed image with less coating unevenness and good abrasion resistance can be obtained. However, when both the above nonionic surfactant and the resin having a weight average molecular weight of 4500 to 500000 are siloxane compounds, they will not be the same compound.

[0031] [Water] The above ink is an aqueous ink containing water. As the water contained in the ink, water with a low content of impurities such as metal ions, that is, ion-exchanged water, distilled water, etc. is preferable. Such water can be prepared by known methods.

[0032] The above ink may further contain a solvent. Examples of the solvent include C1-C6 alkanols having one hydroxy group, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol or tert-butanol; amides such as N,N-dimethylformamide or N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone or N-methylpyrrolidin-2-one; cyclic ureas such as 1,3-dimethylimidazolidin-2-one or 1,3-dimethylhexahydropyrimidin-2-one; ketones or ketoalcohols such as acetone, 2-methyl-2-hydroxypentan-4-one, ethylene carbonate; cyclic ethers such as tetrahydrofuran, dioxane; mono-, oligo- or polyalkylene glycols or thioglycols having C2-C6 alkylene units, such as ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,4-butylene glycol, 1,2-hexylene glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol or polypropylene glycol having a molecular weight of 400 or more, thiodiglycol or dithiodiglycol; polyols (triols) such as glycerin, diglycerin, hexane-1,2,6-triol, trimethylolpropane;Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, propylene glycol monopropyl ether, triethylene glycol monobutyl ether, tripropylene glycol methyl ether, dimethyl glycol, dimethyl diglycol, dimethyl triglycol, methylethyl diglycol, diethyl diglycol, dibutyl diglycol, dimethylpropylene diglycol, dipropylene glycol methyl ether, dipropylene glycol n-propyl ether and other glycol ethers; γ-butyrolactone or dimethyl sulfoxide; C8-C16 (preferably C8-12) alkyl having a hydroxy group and an acyloxy group, etc. Specific examples thereof include, for example, texanol.;

[0033] Among these solvents, it is preferable to contain a solvent selected from glycol ethers, a solvent selected from amides, and a solvent selected from alkanediols. Specific examples thereof include diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, methylethyl diglycol, diethyl diglycol, dipropylene glycol -n- propyl ether, 1,2 - hexanediol, 2 - pyrrolidone, 1,2 - propylene glycol, etc. The above ink preferably contains at least glycol ethers among these.; As the glycol ethers, for example, dialkylene glycol monoalkyl ethers are preferred; di-C2-C3 alkylene glycol mono-C1-C4 alkyl ethers are more preferred; di-C2-C3 alkylene glycol mono-C3-C4 alkyl ethers are even more preferred. Specific examples thereof include diethylene glycol monobutyl ether (butyl diglycol) and dipropylene glycol-n-propyl ether.

[0034] The addition amount of the solvent is preferably 3% or more and 40% or less, more preferably 5% or more and 30% or less in the total amount of the ink.

[0035] The above ink can contain, for example, ink preparation agents such as preservatives, fungicides, pH adjusters, chelating reagents, rust preventives, water-soluble ultraviolet absorbers, antioxidants, resin emulsions, and wax agents, as necessary. Each type of the above ink preparation agents can be used alone or in combination of two or more.

[0036] Examples of the preservative include, for example, organic sulfur-based, organic nitrogen-sulfur-based, organic halogen-based, haloaryl sulfone-based, iodopropargyl-based, haloalkylthio-based, nitrile-based, pyridine-based, 8-oxyquinoline-based, benzothiazole-based, isothiazoline-based, dithiol-based, pyridine oxide-based, nitropropane-based, organotin-based, phenol-based, quaternary ammonium salt-based, triazine-based, thiazine-based, anilide-based, adamantane-based, dithiocarbamate-based, brominated indanone-based, benzyl bromoacetate-based, or inorganic salt-based compounds. Specific examples of commercially available products of the preservative include Proxel GXL(S) and Proxel XL-2(S) manufactured by Arch Chemicals. And Proxel XL-2(S), etc.

[0037] Specific examples of the fungicide include sodium dehydroacetate, sodium benzoate, sodium pyridine thione-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one and its salts, etc.

[0038] As the pH adjuster, any substance can be used as long as it can control the pH within the above range without adversely affecting the prepared ink. Specific examples thereof 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 (aqueous ammonia); or carbonates of alkali metals such as lithium carbonate, sodium carbonate, sodium hydrogen carbonate, and potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; inorganic bases such as disodium phosphate; and the like.

[0039] Specific examples of the chelating reagent include, for example, disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, or sodium uracildiacetate.

[0040] Specific examples of the rust inhibitor include, for example, acid sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, or dicyclohexylammonium nitrite.

[0041] Examples of the water-soluble ultraviolet absorber include, for example, sulfonated benzophenone-based compounds, benzotriazole-based compounds, salicylic acid-based compounds, cinnamic acid-based compounds, or triazine-based compounds.

[0042] Examples of the antioxidant include, for example, various organic-based and metal complex-based anti-fading agents can be used. Examples of the above organic-based anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, or heterocyclics.

[0043] The above resin emulsion refers to a resin obtained by polymerizing one or more constituent monomers and dispersed in the above solvent or the like. Examples of the monomers constituting the resin emulsion include monomers selected from styrene derivatives, methacrylic acid derivatives, and acrylic acid derivatives. The addition amount of the resin emulsion is preferably 0.5% or more and 15% or less, more preferably 1% or more and 10% or less, based on the total amount of the ink.

[0044] The above wax is preferably a wax emulsion dispersed in the above solvent or the like, and particularly preferably an aqueous wax emulsion. As the wax emulsion, natural waxes and chemically synthesized waxes can be used. Examples of natural waxes include paraffin wax, microcrystalline wax, etc. which are petroleum-based waxes, montan wax which is a lignite-based wax, carnauba wax, candelilla wax, etc. which are plant-based waxes, and beeswax, lanolin, etc. which are animal and plant-based waxes, dispersed in an aqueous medium; examples of chemically synthesized waxes include emulsions of polyethylene, polypropylene, Fischer-Tropsch, etc. which are homopolymer waxes, and ethylene vinyl acetate, ethylene acrylic acid, etc. which are copolymer waxes, dispersed in an aqueous medium. These waxes can be used alone or in combination. The addition amount of the wax agent is preferably 0.5% or more and 15% or less, more preferably 1% or more and 10% or less, based on the total amount of the ink.

[0045] Also, if necessary, it is possible to precisely filter the above ink. When performing precise filtration, a membrane filter and / or glass filter paper, etc. can be used. When the above ink is used for inkjet recording, it is preferable to perform precise filtration. The pore size of the filter, etc. when performing precise filtration is usually 0.5 μm to 20 μm, preferably 0.5 μm to 10 μm.

[0046] As for the pH of the above ink, for the purpose of improving storage stability, a pH of 5 to 11 is preferable, and a pH of 6 to 10 is more preferable. Also, as for the surface tension of the ink, 10 to 50 mN / m is preferable, and 20 to 40 mN / m is more preferable. Further, as for the viscosity of the ink, 30 mPa·s or less is preferable, and 20 mPa·s or less is more preferable.

[0047] When using the above ink as an ink for inkjet recording, it is preferable to use one with a low content of inorganic impurities such as chlorides (e.g., sodium chloride) and sulfates (e.g., sodium sulfate) of metal cations contained in the ink. Inorganic impurities are generally often contained in commercially available colorants. The standard of the inorganic impurity content is approximately 1% by mass or less based on the total mass of the colorant, and the lower limit may be below the detection limit of the analytical instrument, that is, 0%. Examples of methods for obtaining a colorant with less inorganic impurities include a method using a reverse osmosis membrane; a method in which the solid of the colorant is suspended and stirred in a mixed solvent of a C1-C4 alcohol such as methanol and water, the colored substance is separated by filtration, and then dried; or a method of exchanging and adsorbing inorganic impurities with an ion exchange resin; and other desalting treatments.

[0048] The above ink can be used in various recording and printing fields. For example, it is suitable for writing aqueous ink, aqueous printing ink, information recording ink, resist dyeing, etc. In particular, it is preferably used for inkjet recording and is preferably used in the inkjet recording method described later.

[0049] The inkjet recording method of the present invention is a method of performing recording by ejecting droplets of the above ink from an inkjet printer and attaching them to a recording medium. There are no particular restrictions on the ink nozzles and the like used during recording, and they can be appropriately selected according to the purpose.

[0050] The above inkjet recording method may be any known method. For example, a charge control method that discharges ink using electrostatic attraction; a drop-on-demand method (also called a pressure pulse method) that uses the vibration pressure of a piezo element; an acoustic inkjet method that converts an electrical signal into an acoustic beam and irradiates the ink, and discharges the ink using the radiation pressure thereof; a thermal inkjet, that is, a bubble jet (registered trademark) method that heats the ink to form bubbles and uses the generated pressure; and the like. In addition, the above inkjet recording method includes a method of ejecting a large number of inks with a low content of a colorant in the ink, called photo ink, in a small volume; a method of improving image quality using a plurality of inks having substantially the same hue but different contents of the colorant in the ink; and a method of improving the fixing property of the colorant to the recording medium by using a colorless and transparent ink and an ink containing a colorant in combination; and the like.

[0051] Also, for example, a recording medium to which the above ink adheres is also included in the scope of the present invention by the above recording method or the like. The recording medium is not particularly limited, but a hardly absorbent recording medium is preferable, and a non-absorbent recording medium is particularly preferable. Examples of hardly absorbent recording media include plain paper without an ink receiving layer, media used for gravure printing, offset printing, etc., art paper, coated paper, matte paper, cast paper, and the like. Examples of non-absorbent recording media include PET (polyethylene terephthalate), PP (polypropylene), vinyl chloride sheet, glass, rubber, and the like.

[0052] When recording on a recording medium by the above inkjet recording method, for example, a container containing the above ink can be set at a predetermined position of an inkjet printer, and recording can be performed on the recording medium by the above recording method. The above inkjet recording method can also be used in combination with one kind or two or more kinds of the inks of the present invention and, if necessary, inks of various colors such as green, blue (or violet), and red (or orange). Each color ink is injected into its respective container, and each container can be loaded into a predetermined position of an inkjet printer in the same manner as the container containing the ink and used for inkjet recording. Industrial inkjet printers are configured as line head type inkjet printers for the purpose of increasing the printing speed, and printing in a single pass is also preferably performed. With the above ink, a printed image excellent in the balance between coating film and scratch resistance can be obtained even under such printing conditions.

[0053] Any one of the above-described all components can be contained alone, or two or more of them can be used in combination. Also, regarding all the above matters and the like, combinations of preferable ones are more preferable, and combinations of more preferable ones are even more preferable. The same applies to combinations of a preferable one and a more preferable one, and combinations of a more preferable one and an even more preferable one.

[0054] By using the ink of the present invention, not only inkjet special paper, general-purpose plain paper, and difficult-to-absorb recording media, but also non-absorbent recording media can be used to obtain a recording image with excellent scratch resistance and no repellency, high image quality. Also, an image with high roundness of ink dots on the medium, smoothness, and no loss of glossiness can be obtained. Furthermore, a recording image excellent in various fastnesses such as water resistance, light resistance, heat resistance, and oxidation gas resistance (for example, ozone gas resistance) can be obtained. Moreover, the storage stability of the ink is also good, and stable ejection performance can be ensured over a long period.

Examples

[0055] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by the following examples. In the text, "parts" and "%" are based on mass unless otherwise specified. Also, all operations such as each synthesis reaction and crystallization were carried out under stirring unless otherwise specified. Also, when it is necessary to measure the solid content of the colorant contained in various liquids, it was calculated as the conversion value of only the colorant by the dry weight method using MS-70 manufactured by A&D Company, Limited.

[0056] [Preparation Example 1]: Preparation of a dispersion. A block copolymer described in Synthesis Example 3 of International Publication No. 2013 / 115071 was prepared, and 6 parts of the obtained polymer dispersant was dissolved in 30 parts of 2-butanone to form a uniform solution. To this solution, a solution prepared by dissolving 0.68 part of a 28% aqueous ammonia solution in 53 parts of ion-exchanged water was added, and the mixture was stirred for 1 hour to prepare an emulsified solution in which the polymer dispersant was dissolved. 20 parts of C.I.Pigment Blue 15:3 (Cyanine Blue A220J manufactured by Dainichi Seika Kogyo Co., Ltd.) was added thereto, and dispersion treatment was carried out in a sand grinder under the condition of 1500 rpm for 15 hours. 100 parts of ion-exchanged water was added dropwise to the obtained solution, and after filtering to remove the dispersion beads, 2-butanone and water were distilled off under reduced pressure using an evaporator to obtain a cyan dispersion having a pigment solid content of 11.9%. The obtained colored dispersion is designated as "Dp1".

[0057] [Examples 1 to 5 and Comparative Examples 1 to 2]: Preparation of inks. The dispersion "Dp1" obtained above was mixed with each component described in Table 1 below to obtain an ink, and then each ink for the evaluation test of Examples 1 to 5 and Comparative Examples 1 to 2 for comparison was obtained by filtering through a 3-μm membrane filter. The content of the colorant in the total mass of the ink was adjusted to 4% for all inks.

[0058] The abbreviations and the like in Table 1 below have the following meanings. Dp1: The colored dispersion obtained in Preparation Example 1. BDG: Butyl diglycol. DPGPE: Dipropylene glycol n-propyl ether. NT-3: Newcol NT-3 (HLB value 7.9). NT-5: Newcol NT-5 (HLB value 10.5). NT-12: Newcol NT-12 (HLB value 12.1). NF-13: Hitenol NF-13 (anionic surfactant, HLB value 13 - 15). BYK-3450: silicone-based surfactant (HLB value 13.8) BYK-3451: silicone-based surfactant (HLB value 9.7) BYK-3760: siloxane compound (Mw. 6800). TG490: TEGO Glide 490, siloxane compound (Mw. 31000).

[0059]

Table 1

[0060] [Coating unevenness evaluation] The inks of the above examples and comparative examples were applied to the entire surface of a PET sheet (manufactured by Toyobo Co., Ltd., E5100) using a bar coater No. 3 with an automatic coater (manufactured by Tester Sangyo Co., Ltd., PI-1210). Then, a test print was obtained by drying it in a thermostatic bath at 70°C for 2 minutes. The obtained test print was visually observed, and the coating unevenness was evaluated according to the following criteria. The results are shown in Table 2 below. D: There is a lot of coating unevenness and it is not uniform. C: Coating unevenness is observed. B: It seems that there is slightly coating unevenness. A: There is no coating unevenness and it is uniform.

[0061] [Abrasion resistance test] The obtained test print was rubbed 10 times between PET films using a Kagaku Shinkou test machine manufactured by Yasuda Seiki Co., Ltd. with a load of 250 g to obtain a test print. The obtained test print was visually observed, and the state of the rubbed surface was evaluated according to the following criteria. The results are shown in Table 2 below. D: The rubbed surface is completely peeled off and no ink remains. C: About half of the rubbed surface is peeled off. B: The rubbed surface is scraped and a little ink is peeled off. A: The rubbed surface is not scraped and no ink is peeled off at all. The results are shown in Table 2 below.

[0062] [Table 2]

[0063] [Examples 6 to 13 and Comparative Examples 3 to 4]: Preparation of ink. The dispersion liquid "Dp1" obtained above was mixed with each component described in Table 3 below to obtain an ink, and then each ink for the evaluation test of Examples 6 to 13 and Comparative Examples 3 to 4 for comparison was obtained by filtering with a 3-μm membrane filter. The content of the colorant in the total mass of the ink was adjusted to 4% for all inks.

[0064] The abbreviations and the like in Table 3 below have the following meanings. Among the components in Table 3 below, the numerical values in parentheses are HLB values. Dp1: Colored dispersion liquid obtained in Preparation Example 1. BDG: Butyl diglycol. DPGPE: Dipropylene glycol-n-propyl ether. NT-5: Newcol NT-5. TDX-50: (Neugen TDX-50). EA197D: (Neugen EA197D). SAG503A: (Silface SAG503A). SF465: Surfynol 465. FS-30: Capstone FS-30. TG490: TEGO Glide 490, siloxane compound (Mw. 31000). TG450: TEGO Glide 450, siloxane compound (Mw. 4100). HA-15: Evafarl HA-15 (Mw. 113000). A-655: NeoCryl A-655 (Mw. 83000). IE7170: DOWSIL IE-7170, siloxane compound (Mw. 282799).

[0065]

Table 3

[0066] Using the inks of Examples 4 to 9 and Comparative Examples 3 to 4 above, [coating unevenness evaluation] and [rub resistance test] were each carried out in the same manner as above. The evaluation results are shown in Table 4 below.

[0067]

Table 4

[0068] As is clear from the above results, for the inks of the examples, all evaluation results were "A" or "B", while for the inks of the comparative examples, one of the evaluation results was "C" or below. From these results, it was confirmed that the inks of the examples are superior in the balance between coating unevenness and rub resistance compared to the comparative examples.

[0069] [Inkjet printing test] Each ink of the examples and comparative examples was used, and inkjet recording was performed on PET E5100 (manufactured by Toyobo Co., Ltd.) as a recording medium using an inkjet printer, model name PX205, manufactured by Seiko Epson Corporation. As a result, it was confirmed that all the inks were ejected from the inkjet printer without problems and inkjet recording could be performed on the recording medium.

Industrial applicability

[0070] According to the present invention, it was possible to provide an ink excellent in the balance between coating unevenness and rub resistance, and a recording medium to which the ink was adhered. Therefore, the ink of the present invention is extremely useful as various recording inks.

Claims

1. An ink containing a water-insoluble colorant, a dispersant with an acid value of 90 to 200 mgKOH / g, water, a nonionic surfactant with an HLB value of more than 7.9 and not more than 20.0, and a resin with a weight-average molecular weight of 4,500 to 500,000. However, when the nonionic surfactant and the resin with a weight-average molecular weight of 4,500 to 500,000 are both siloxane compounds, the two will not be the same compound.

2. The ink according to claim 1, further comprising glycol ethers.

3. 3. The ink of claim 2, wherein the glycol ether is an alkylene glycol monoalkyl ether.

4. A recording medium having the ink according to any one of claims 1 to 3 adhered thereto.

5. An inkjet recording method comprising ejecting droplets of the ink according to any one of claims 1 to 3 from an inkjet printer and depositing the droplets on a recording medium to perform recording.