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 technology]

[0002] Among various color recording methods, the recording method using an inkjet printer is one of the most representative methods, in which small droplets of ink are generated and deposited on a recording medium such as paper to record. In recent years, demand for inkjet printers for industrial use has increased, and there is a demand for them to be compatible with a variety of recording media.

[0003] In particular, for non-ink-absorbent media (hereinafter referred to as "non-absorbent media") such as film, development has progressed on solvent inks that use organic solvents as the main ingredient, UV inks that contain polymerizable monomers, etc. However, these inks have many safety issues, such as VOCs and skin sensitization, and their applications have been limited.

[0004] Therefore, as described in Patent Documents 1 and 2, there has been active development of water-based inks that contain water as the main component but contain polymer particles or the like, making it possible to print highly durable images even on non-absorbent media.

[0005] However, even when using inks obtained through these proposals, the scratch resistance of non-absorbent media such as PET (polyethylene terephthalate) and PP (polypropylene) is insufficient, and improvements are needed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5504890 [Patent Document 2] Patent No. 6295825 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide an ink that enables the production of printed matter with an excellent balance between coating unevenness and abrasion resistance, an inkjet recording method using the ink, and a recording medium to which the ink is attached. [Means for solving the problem]

[0008] As a result of extensive research into solving the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by the ink, recording medium, and recording method described in [1] to [5] below, 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 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, if the nonionic surfactant and the resin with a weight-average molecular weight of 4,500 to 500,000 are both siloxane compounds, they will not be the same compound. [2] The ink according to [1], further comprising glycol ethers. [3] The ink according to [2], wherein the glycol ether is an alkylene glycol monoalkyl ether. [4] A recording medium having the ink according to any one of [1] to [3] adhered thereto. [5] An inkjet recording method in which droplets of the ink according to any one of [1] to [3] are ejected from an inkjet printer and deposited on a recording medium, thereby performing recording. [Effects of the Invention]

[0010] The present invention provides an ink that enables the production of printed matter with an excellent balance between coating unevenness and abrasion resistance, an inkjet recording method using the ink, and recording media colored with the ink. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Water-insoluble colorants] The 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, a water-insoluble colorant means a colorant whose solubility in 1 liter of water at 25°C is usually 5 g or less, preferably 3 g or less, more preferably 1 g or less, and even more preferably 0.5 g or less. The lower limit of the solubility includes 0 g. Unless otherwise specified, the "water-insoluble colorant" will be referred to as the "colorant" hereinafter. Colorants can be used in combination. The ink typically contains three or more types of colorants, preferably three to five types in the case of black ink, and typically three types, preferably two or one type, in the case of color inks other than black ink. However, when the black ink contains carbon black as a colorant, two or one type of colorant is preferred. In this specification, color ink refers to colored inks other than black ink (e.g., inks of colors such as yellow, magenta, cyan, red, orange, brown, violet, blue, and green). Among pigments, disperse dyes, and solvent dyes, pigments are preferred. 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] The 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, and channel black. 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 ColorBlack series, Printex series, SpecIalBlack 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.

[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 yellows 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, 155, 180, 185, 193, 199, 202, and 213; and CI Pigment Red Reds 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, and 272; Blues 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; Violets such as CI Pigment Violet 19, 23, 29, 37, 38, and 50; Oranges such as CI Pigment Orange 13, 16, 68, 69, 71, and 73; Greens such as CI Pigment Green 7, 36, and 54; and CI Pigment Examples of pigments include various black colors such as Black 1.

[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] The disperse dye may be any known disperse dye, and among them, dyes selected from CI Disperses are preferred. Specific examples thereof include yellows 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; reds 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. Examples of disperse dyes include oranges 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; violets such as CI Disperses Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, and 79:1; and blues such as CI Disperses 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.

[0018] The content of the colorant relative to the total mass of the ink is usually 1 to 30%, preferably 1 to 10%, and more preferably 2 to 7%. The average particle size of the colorant is usually 50 nm to 250 nm, and preferably 60 nm 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.

[0019] [Dispersant] The 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. Polymer dispersants such as resins are generally used as dispersants. Examples of such resins include polymers derived from polyvinyl alcohol, cellulose derivatives, polyethylene oxide, polypropylene oxide, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoesters, maleic acid, maleic acid monoesters, fumaric acid, fumaric acid monoesters, vinyl sulfonic acid, sulfoethyl methacrylate, sulfopropyl methacrylate, ionic monomers such as α,β-unsaturated monomers of sulfonated vinylnaphthalene, styrene, styrene derivatives, vinylnaphthalene, vinylnaphthalene 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, and N-butoxymethylacrylamide.

[0020] Examples of the dispersant include the same dispersants as those for the AB block polymer disclosed in WO 2013 / 115071, including preferred examples. The same applies to the method for producing the AB block polymer. One example of a dispersant (AB block polymer) disclosed in WO 2013 / 115071 Gazette is one in which the monomer constituting the A polymer is one or more monomers selected from (meth)acrylic acid and linear or branched C4 alkyl (meth)acrylates, 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 include both "acrylic, methacrylic" and "acrylate, methacrylate," respectively. The monomer constituting the A block is preferably one or more monomers selected from methacrylic acid and n-butyl methacrylate, and it is particularly preferable to use these two types of monomers in combination. The monomer constituting the B block is preferably benzyl methacrylate. Specific examples thereof include the block copolymers disclosed in Synthesis Examples 3 to 8 of the International Publication Gazette.

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

[0022] The acid value of the dispersant is usually 90 to 200 mgKOH / g, preferably 100 to 150 mgKOH / g, and 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 the content within the above range, the dispersibility and storage stability can be improved. Examples of the neutralizing agent include ammonia, hydroxides of alkali metals, hydroxides of alkaline earth metals, aliphatic amine compounds, alkanolamine compounds, etc. Ammonia and hydroxides of alkali metals are preferred, and ammonia is particularly preferred. The amount of neutralizer used is not particularly limited. As a guideline, the degree of neutralization is usually 30 to 300%, more preferably 50 to 200%, with 100% neutralization being achieved when neutralized with an amount theoretically equivalent to the acid value of the dispersant.

[0023] The above dispersants can be used in a mixed state with a water-insoluble colorant. Alternatively, they can be used in a state in which the surface of the water-insoluble colorant is coated with the dispersant. Alternatively, both of these can be used in combination. In this specification, "coated" refers to both a state in which the entire surface of the water-insoluble colorant is coated with the dispersant and a state in which only a portion of the surface of the water-insoluble colorant is coated with the dispersant. When a dispersant is used, 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, and more preferably 0.2 to 0.5.

[0024] [Nonionic surfactants with an HLB value of more than 7.9 and less than 20.0] The nonionic surfactants having an HLB value of greater than 7.9 and less than 20.0 are not particularly limited as long as they have an HLB value of greater than 7.9 and less than 20.0, and examples include the "general-purpose nonionic surfactants," "silicon-based nonionic surfactants," and "fluorine-based nonionic surfactants" described below. Compared to ionic surfactants, nonionic surfactants are less likely to cause intermolecular interactions such as ionic bonds and are more likely to lower surface tension. This makes them more likely to wet media and reduce coating unevenness in printed materials.

[0025] Examples of the "general-purpose nonionic surfactant" include polyoxyalkylene alkyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene tridecyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and polyoxyethylene alkyl ether; polyoxyalkylene acylates such as polyoxyethylene oleate, polyoxyethylene distearate, 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) 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 surfactants. Nonionic surfactants are available, for example, as the Surfynol series, such as Surfynol 465, and the Olfine series, available from Nissin Chemical Co., Ltd.; the Emulgen series, available from Kao Corporation; the Newcol series, available from Nippon Nyukazai Co., Ltd. (e.g., Newcol NT-5 and 12, which are polyoxyethylene alkyl ethers); and the Noigen series, available from Dai-ichi Kogyo Seiyaku Co., Ltd. (e.g., Noigen TDX-50, which is a polyoxyalkylene tridecyl ether, and Noigen EA197D, which is a polyoxyethylene styrenated phenyl ether).

[0026] Examples of the "silicon-based nonionic surfactant" include siloxane compounds such as polyether-modified siloxane and polyether-modified polydimethylsiloxane. Examples of commercially available surfactants include Dynol 960 and Dynol 980 manufactured by Air Products Co., Ltd., Silface SAG001, Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG503A, Silface SAG008, Silface SAG009, and Silface SAG010 manufactured by Nissin Chemical Industry Co., Ltd., and BYK-345, BYK-347, BYK-348, BYK-349, BYK-3455, BYK-LP-X23288, BYK-3451 (also known as BYKLPX 23347), and BYK-3450 (also known as BYKLPX 23289) manufactured by BYK-Chemie.

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

[0028] The HLB value of the above nonionic surfactants is greater than 7.9 and equal to or less than 20.0, preferably 8.0 to 18.0, and more preferably 9.0 to 18.0. In this specification, the HLB value is rounded to one decimal place and is stated to one decimal place. Alternatively, it can be determined as an actual measured value through experiments. Known methods can be used for this purpose. One example is the Griffin method described in the gazette of International Publication No. 2017 / 159685. The HLB value can be calculated using the following formula (1). Note that the "HLB value" described in this specification refers to the HLB value calculated using the Griffin method when the structure of the compound used is clearly known. HLB value = 20 × (sum of molecular weights of hydrophilic parts) ÷ (molecular weight of material) Equation (1) In addition, if the HLB value is listed in a catalogue or the like of the manufacturer or distributor, that value can also be used. If the above HLB value does not have decimal places, the first decimal place should be considered as "zero" and the value should be entered up to the first decimal place.

[0029] [Resin with a weight-average molecular weight of 4,500 to 500,000] Resins typically used in aqueous inkjet inks are used to provide adhesion to substrates and durability to the printed surface. The resin structures used vary widely, including acrylic, styrene-acrylic, urethane, olefin, and paraffin. However, a common thread among these resins is that the higher the molecular weight of the resin, the stronger the film formed. Film strength is determined by the resin's glass transition temperature, which increases with increasing molecular weight. Therefore, the higher the molecular weight of the resin used, the stronger the printed surface. Examples of resins with a weight-average molecular weight of 4,500 to 500,000 include Evafal HA-15 manufactured by Nicca Chemical Co., Ltd. and NeoCryl A-655 manufactured by DSM Coating Resin. The weight-average molecular weight of the resin is preferably 5,000 to 400,000, more preferably 6,500 to 300,000. Another example of such a resin is the siloxane compound described below.

[0030] [Siloxane compounds] Siloxane is a compound with a silicon-oxygen skeleton and is known as a general term for compounds with Si-O-Si bonds. The aforementioned siloxane compounds include those with a siloxane structure that exhibits properties that improve the slipperiness of paint surfaces. The reason that compounds with a long siloxane skeleton are considered effective is due to the effect of film formation on the ink surface. As the siloxane skeleton length increases, the hydrophobicity increases, and the siloxane compound floats on the ink surface after drying, forming a micro-film. This micro-film acts as a lubricant, reducing the coefficient of friction and enhancing slipperiness. Siloxane compounds with a short siloxane skeleton and a molecular weight below 4500 have weak siloxane bond linearity and are prone to hydrogen bonding, resulting in weak hydrophobic properties. As a result, they are said to exhibit poor slipperiness. Examples of siloxane compounds include dimethylsiloxane, methylsiloxane, and silanol. Dimethylsiloxane is particularly hydrophobic and easily forms a silicone film on the ink surface during the drying process, thereby exhibiting superior slip properties. The silicone surfactants described above have short main chains and do not exhibit slip properties, so the difference between these and the present siloxane compounds can be explained by their 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. Siloxane compounds with a weight-average molecular weight within this range are preferred. By incorporating such compounds into the ink, printed images with minimal coating unevenness and excellent abrasion resistance can be obtained. However, when the nonionic surfactant and the resin having a weight average molecular weight of 4,500 to 500,000 are both siloxane compounds, they are not the same compound.

[0031] [water] The ink is an aqueous ink containing water. The water contained in the ink is preferably water with a low content of impurities such as metal ions, i.e., ion-exchanged water, distilled water, etc. Such water can be prepared by a known method.

[0032] The ink may further contain a solvent, such as a C1-C6 alkanol having one hydroxy group, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, or tert-butanol; an amide, such as N,N-dimethylformamide or N,N-dimethylacetamide; a lactam, such as 2-pyrrolidone, N-methyl-2-pyrrolidone, or N-methylpyrrolidin-2-one; a cyclic urea, such as 1,3-dimethylimidazolidin-2-one or 1,3-dimethylhexahydropyrimid-2-one; a ketone or ketoalcohol, such as acetone, 2-methyl-2-hydroxypentan-4-one, or ethylene carbonate; a cyclic ether, such as tetrahydrofuran or dioxane; or an ethylene carbonate. Mono-, oligo-, or polyalkylene glycols or thioglycols having C2-C6 alkylene units, such as 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, and trimethylolpropane;Examples of suitable alkyl ethers include glycol ethers such as 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, methyl ethyl diglycol, diethyl diglycol, dibutyl diglycol, dimethyl propylene diglycol, dipropylene glycol methyl ether, and dipropylene glycol n-propyl ether; γ-butyrolactone or dimethyl sulfoxide; and C8-C16 (preferably C8-12) alkyl esters having a hydroxy group and an acyloxy group. Specific examples include, for example, Texanol.

[0033] Among these solvents, it is preferable to include a solvent selected from glycol ethers, amides, or alkanediols. Specific examples include diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, methyl ethyl diglycol, diethyl diglycol, dipropylene glycol-n-propyl ether, 1,2-hexanediol, 2-pyrrolidone, and 1,2-propylene glycol. Of these, it is preferable that the ink contains at least glycol ethers. 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, and 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 amount of solvent added is preferably 3% to 40% of the total amount of ink, and more preferably 5% to 30%.

[0035] The ink may contain, as necessary, ink preparation agents such as preservatives, antifungals, pH adjusters, chelating agents, rust inhibitors, water-soluble ultraviolet absorbers, antioxidants, resin emulsions, waxes, etc. Each of the above ink preparation agents may be used alone or in combination of two or more.

[0036] Examples of preservatives include organic sulfur compounds, organic nitrogen sulfur compounds, organic halogen compounds, haloarylsulfone 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 commercially available preservatives include those manufactured by Arch Chemical Company under the trade names Proxel GXL(S) and Proxel XL-2(S).

[0037] Specific 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.

[0038] Any substance can be used as the pH adjuster as long as it can control the pH within the above range without adversely affecting the ink being prepared. Specific examples 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.

[0039] Specific examples of the chelating agent include disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uracildiacetate.

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

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

[0042] Examples of the antioxidant include various organic and metal complex anti-fading agents, such as hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles.

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

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

[0045] Furthermore, the ink can be microfiltered as needed. When microfiltering, a membrane filter and / or glass filter paper can be used. When using the ink for inkjet recording, microfiltration is preferably performed. The pore size of the filter used for microfiltration is usually 0.5 μm to 20 μm, preferably 0.5 μm to 10 μm.

[0046] To improve storage stability, the pH of the ink is preferably 5 to 11, more preferably 6 to 10. The surface tension of the ink is preferably 10 to 50 mN / m, more preferably 20 to 40 mN / m. The viscosity of the ink is preferably 30 mPa·s or less, more preferably 20 mPa·s or less.

[0047] When the ink is used as an ink for inkjet recording, it is preferable to use an ink containing a low content of inorganic impurities, such as chlorides (e.g., sodium chloride) and sulfates (e.g., sodium sulfate) of metal cations. Inorganic impurities are generally contained in commercially available colorants. The inorganic impurity content is generally approximately 1% by mass or less of the total mass of the colorant, with the lower limit being below the detection limit of analytical instruments, i.e., 0%. Methods for obtaining colorants with low inorganic impurities include desalination processes such as using a reverse osmosis membrane; suspending and stirring a solid colorant in a mixed solvent of C1-C4 alcohol (e.g., methanol) and water, filtering and separating the colored product, and drying it; or exchanging and adsorbing inorganic impurities with an ion exchange resin.

[0048] The ink can be used in various fields of recording and printing. For example, it is suitable as a water-based ink for writing, a water-based printing ink, an information recording ink, textile printing, etc. It is particularly preferred for use in inkjet recording, and is suitable for use in the inkjet recording method described below.

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

[0050] The inkjet recording method may be any known method, such as a charge control method that uses electrostatic attraction to eject ink, a drop-on-demand method (also called a pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink with the resulting radiation pressure to eject the ink, or a thermal inkjet, i.e., a bubble jet (registered trademark) method, that heats the ink to form bubbles and uses the resulting pressure. The inkjet recording method also includes a method of ejecting a large number of small volumes of inks called photo inks, which have a low content of colorant; a method of improving image quality by using a plurality of inks that have substantially the same hue but different content of colorant; and a method of improving the fixability of colorant to recording media by using a colorless, transparent ink in combination with an ink that contains a colorant.

[0051] Also included within the scope of the present invention is a recording medium to which the ink has been applied, for example, by the recording method described above. While there are no particular limitations on the recording medium, poorly absorbent recording media are preferred, and non-absorbent recording media are particularly preferred. Examples of poorly absorbent recording media include plain paper without an ink-receiving layer, media used in gravure printing and offset printing, art paper, coated paper, matte paper, and cast paper. Non-absorbent recording media include PET (polyethylene terephthalate), PP (polypropylene), vinyl chloride sheets, glass, and rubber.

[0052] When recording on a recording medium using the inkjet recording method, for example, a container containing the ink can be set at a predetermined position on an inkjet printer, and recording can be performed on the recording medium using the inkjet recording method. In the inkjet recording method, one or more inks of the present invention may be used in combination with inks of other colors such as green, blue (or violet), and red (or orange), as required. Each color ink is poured into a respective container, and each container can be loaded into a predetermined position in the ink jet printer in the same way as the container containing the ink, and used for ink jet recording. Industrial inkjet printers are preferably configured as line-head inkjet printers for the purpose of achieving high printing speeds, and single-pass printing is also preferred. The ink described above can produce printed images with an excellent balance of coating quality and abrasion resistance even under such printing conditions.

[0053] All of the above-mentioned components can be contained alone or in combination of two or more. Furthermore, for all of the above-mentioned items, a combination of preferred items is more preferred, and a combination of more preferred items is even more preferred. The same applies to a combination of a preferred item and a more preferred item, and a combination of a more preferred item and an even more preferred item.

[0054] By using the ink of the present invention, it is possible to obtain high-quality recorded images that are excellent in abrasion resistance and do not repel blemishes, not only on inkjet paper, general-purpose plain paper, and low-absorbency recording media, but also on non-absorbency recording media. Furthermore, it is possible to obtain images with high ink dot roundness on the media, smoothness, and no loss of gloss. Furthermore, it is possible to obtain recorded images that are excellent in various fastness properties, such as water resistance, light resistance, heat resistance, and resistance to oxidizing gases (e.g., ozone gas). Furthermore, the ink has good storage stability, ensuring stable ejection performance over a long period of time. [Example]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the text, "parts" and "%" are by mass unless otherwise specified. Furthermore, all synthetic reactions and operations such as crystallization were carried out under stirring unless otherwise specified. In addition, when it was necessary to measure the solid content of the colorant contained in various liquids, the solid content was calculated as the equivalent value of the colorant only using the dry weight method using an MS-70 manufactured by A&D Co., Ltd.

[0056] [Preparation Example 1]: Preparation of dispersion. A block copolymer was prepared as described in Synthesis Example 3 of WO 2013 / 115071. 6 parts of the resulting polymeric dispersant was dissolved in 30 parts of 2-butanone to form a homogeneous solution. To this solution, 0.68 parts of 28% aqueous ammonia dissolved in 53 parts of ion-exchanged water was added and stirred for 1 hour to prepare an emulsified solution containing the polymeric dispersant. 20 parts of CI Pigment Blue 15:3 (Cyanine Blue A220J, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) was added, and the mixture was dispersed in a sand grinder at 1500 rpm for 15 hours. 100 parts of ion-exchanged water was added dropwise to the resulting solution, filtered to remove the dispersion beads, and then the 2-butanone and water were distilled off under reduced pressure using an evaporator to obtain a cyan dispersion with a pigment solids content of 11.9%. The resulting colored dispersion was designated "Dp1."

[0057] [Examples 1 to 5 and Comparative Examples 1 to 2]: Preparation of ink. The dispersion "Dp1" obtained above was mixed with each of the components listed in Table 1 below to obtain inks, which were then filtered through a 3 μm membrane filter to obtain the inks of Examples 1 to 5 for evaluation tests and Comparative Examples 1 and 2 for comparison. The content of the colorant in the total mass of the ink was adjusted to 4% for all inks.

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

[0059] [Table 1]

[0060] [Evaluation of coating unevenness] The inks of the above examples and comparative examples were applied to the entire surface of a PET sheet (E5100, manufactured by Toyobo Co., Ltd.) using an automatic coater (PI-1210, manufactured by Tester Sangyo Co., Ltd.) with a bar coater No. 3. The sheet was then dried in a thermostatic chamber at 70°C for 2 minutes to obtain a test print. The obtained test prints were visually observed, and coating unevenness was evaluated according to the following criteria. The results are shown in Table 2 below. D: There is a lot of unevenness in the coating and it is not uniform. C: Coating unevenness is observed. B: There appears to be some unevenness in the coating. A: The coating is even and uniform.

[0061] [Abrasion resistance test] The resulting test print was rubbed against another PET film 10 times using a Gakushin tester manufactured by Yasuda Seiki Seisakusho Co., Ltd. with a load of 250 g to obtain a test print. The resulting test print was visually observed, and the condition of the rubbed surface was evaluated according to the following criteria. The results are shown in Table 2 below. D: The abraded surface is completely peeled off and no ink remains. C: About half of the abraded surface peels off. B: The rubbed surface is scraped and some ink is removed. A: The abraded surface is not scraped and the ink does not come 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 inks. The dispersion "Dp1" obtained above was mixed with each of the components listed in Table 3 below to obtain inks, which were then filtered through a 3 μm membrane filter to obtain the inks of Examples 6 to 13 for evaluation tests and Comparative Examples 3 and 4 for comparison. The content of the colorant in the total mass of the ink was adjusted to 4% for all inks.

[0064] The abbreviations in Table 3 below have the following meanings: Furthermore, among the components in Table 3 below, the values ​​in parentheses are HLB values. Dp1: Colored dispersion obtained in Preparation Example 1. BDG: butyl diglycol. DPGPE: Dipropylene glycol-n-propyl ether. NT-5: Nucol NT-5. TDX-50:(Noigen TDX-50). EA197D:(Noigen EA197D). SAG503A: (Silface SAG503A). SF465: Surfynol 465. FS-30: Capstone FS-30. TG490: TEGO Glide 490, a siloxane compound (Mw. 31000). TG450: TEGO Glide 450, a siloxane compound (Mw. 4100). HA-15: Evafar HA-15 (Mw. 113,000). A-655: NeoCryl A-655 (Mw.83000). IE7170: DOWSIL IE-7170, a siloxane compound (Mw. 282799).

[0065] [Table 3]

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

[0067] [Table 4]

[0068] As is clear from the above results, the inks of the examples received evaluation results of "A" or "B," while the inks of the comparative examples received evaluation results of "C" or lower. These results confirm that the inks of the examples have a better balance between coating unevenness and abrasion resistance than the comparative examples.

[0069] [Inkjet printing test] Using each of the inks of the Examples and Comparative Examples, inkjet recording was carried out on PET E5100 (manufactured by Toyobo Co., Ltd.) as recording media using an inkjet printer (product name: PX205) manufactured by Seiko Epson Corp. As a result, it was confirmed that all of the inks were ejected from the inkjet printer without any problems, and that inkjet recording was possible on the recording media. [Industrial Applicability]

[0070] The present invention provides an ink that can provide a recorded image with an excellent balance between coating unevenness and abrasion resistance, and a recording medium to which the ink is applied. For this reason, the ink of the present invention is extremely useful as a recording ink for various purposes.

Claims

1. An ink containing a water-insoluble colorant, a dispersant having a mass average molecular weight of 10,000 to 40,000 and an acid value of 100 to 150 mgKOH / g, water, a nonionic surfactant having an HLB value of more than 7.9 and not more than 20.0, a resin having a weight average molecular weight of 4,500 to 500,000, and glycol ethers in an amount of 3 to 15% of the total amount of ink, 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. 2. The ink of claim 1, wherein the glycol ether is an alkylene glycol monoalkyl ether.

3. A recording medium having the ink according to any one of claims 1 to 2 adhered thereto.

4. An inkjet recording method comprising ejecting droplets of the ink according to any one of claims 1 and 2 from an inkjet printer and depositing the droplets on a recording medium to perform recording.

Images