Water-based ink composition and method for manufacturing inkjet printed materials

Abstract

To provide an inkjet recording water-based ink that contains surfactants and water-soluble organic solvents while maintaining the water repellency of the nozzle plate and having good stability. [Solution] The present invention provides an aqueous ink composition containing a non-white colorant (A), a water-soluble organic solvent (B), a surfactant (C), and water, wherein the surfactant (C) comprises an acetylenediol-based surfactant (C-1) and a silicone-based surfactant (C-2), the water-soluble organic solvent (B) is contained in a quantity greater than 0% by mass and less than or equal to 10% by mass, and the weight ratio (C-1 / C-2) of the acetylenediol-based surfactant (C-1) to the silicone-based surfactant (C-2) is 0.10 or more and less than or equal to 0.49.

Description

Technical Field

[0001] The present invention relates to an aqueous ink composition and a method for producing an inkjet printed matter.

Background Art

[0002] Among various color recording methods, the recording method using an inkjet printer, which is one of the representative methods, generates fine ink droplets using an inkjet head and deposits them on various recording materials to perform recording. In the field of high-definition printing that has been realized by silver halide photography and offset printing so far, the inkjet recording method has also come to be used. In recent years, demand for industrial applications has increased, and printing on various recording media including packaging materials such as corrugated cardboard sheets and corrugated boxes, and poorly absorbent base materials such as coated paper has been required.

[0003] As a method for producing corrugated cardboard sheets and corrugated boxes, there is a pre-printing method that continuously performs a printing step of printing on liner paper or coated cardboard wound into a roll, a laminating step of performing lamination by the corrugator treatment to obtain a corrugated cardboard sheet, and a box making step of cutting the obtained corrugated cardboard sheet to form a corrugated box.

[0004] Analog printing is mainly used as the printing method applied in the pre-printing method, but since the organic solvent contained in the ink used for analog printing has a large adverse effect on the environment and the human body, inkjet printing using aqueous ink that does not contain volatile organic solvents as much as possible has been required.

[0005] However, a problem of inkjet printing is abrasion of the water-repellent film of the inkjet head.

[0006] The inkjet head is equipped with a nozzle plate having multiple ejection ports made of silicon and silicon oxide. To maintain ink ejection performance, the nozzle plate has a water-repellent film on its surface, preventing problems such as print distortion by preventing the ink composition ejected from the nozzles from adhering to the vicinity of the nozzles.

[0007] Inkjet printers often use water-based inks containing specific surfactants or a certain amount or more of water-soluble organic solvents, as described in Patent Documents 1 to 3, to improve wettability and penetration to recording media, and to improve the moisture retention of the ink itself. However, when such inks are filled into inkjet heads for extended periods, the water repellency of the water-repellent film deteriorates due to contact with the ink, leading to a decrease in ejection reliability.

[0008] For these reasons, there is a strong market demand for water-based inkjet inks that contain surfactants and water-soluble organic solvents while maintaining the water repellency of the nozzle plate and possessing good stability. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2007-262272 [Patent Document 2] Japanese Patent Publication No. 2011-56832 [Patent Document 3] Japanese Patent Publication No. 2019-119786 [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention aims to provide a water-based ink composition that suppresses erosion of the nozzle plate and a method for manufacturing inkjet printed materials. [Means for solving the problem]

[0011] The inventors of this invention conducted extensive research to solve the above problems and, as a result, found that the above problems can be solved by the inventions described in 1) to 13) below, and thus completed the present invention.

[0012] 1) A water-based ink composition comprising a non-white colorant (A), a water-soluble organic solvent (B), a surfactant (C), and water, wherein the surfactant (C) comprises an acetylenediol-based surfactant (C-1) and a silicone-based surfactant (C-2), the water-soluble organic solvent (B) content is greater than 0% by mass and 10% by mass or less, and the weight ratio (C-1 / C-2) of the acetylenediol-based surfactant (C-1) to the silicone-based surfactant (C-2) is 0.10 or more and 0.49 or less. 2) The aqueous ink composition according to 1), wherein the content of the silicone-based surfactant (C-2) is 0.5% by mass or more. 3) The aqueous ink composition according to 1), wherein the HLB value of the acetylenediol-based surfactant (C-1) is 4 or more and 13 or less. 4) The aqueous ink composition according to 1), wherein the water-soluble organic solvent (B) contains one or more organic solvents having a ClogP value of 0.5 or more and 2.8 or less. 5) The aqueous ink composition according to 1), wherein the non-white colorant (A) is a pigment. 6) Furthermore, the aqueous ink composition according to 1) further contains a humectant (D). 7) The aqueous ink composition according to 6), wherein the humectant (D) is a sugar alcohol. 8) The aqueous ink composition according to 7), wherein the sugar alcohol is sorbitol. 9) A method for producing an inkjet printed material, comprising ejecting droplets of the aqueous ink composition described in any one of items 1) to 8) from an inkjet head and adhering them to a printing medium to obtain a printed material. 10) The method for producing an inkjet printed matter according to 9), wherein the printing medium is at least one selected from the group consisting of corrugated fiberboard, liner paper, and coated cardboard. 11) The method for producing an inkjet printed matter according to 9), wherein the printing medium is coated paper. 13) A method for producing an inkjet printed matter, comprising continuously performing: a printing step of ejecting droplets of the water-based ink composition according to any one of 1) to 8) from an inkjet head in a single-pass system to adhere the droplets to liner paper or coated cardboard to obtain a printed matter; and a laminating step of bonding the printed matter to a corrugating medium to obtain a corrugated fiberboard sheet. Effects of the Invention

[0013] The present invention provides a water-based ink composition that suppresses erosion of nozzle plates, and a method for producing an inkjet printed matter. Modes for Carrying Out the Invention

[0014] In the present specification, "C.I." is an abbreviation for Color Index. Further, in the present specification, the numerical values for "%" and "part(s)" are all described on a mass basis unless otherwise specified. "(Meth)acrylic" is used to include both "acrylic" and "methacrylic". The same applies to "(meth)acrylate" and the like. In addition, the water-based ink composition may be abbreviated as ink in some cases.

[0015] [Water-based Ink Composition] The water-based ink composition of the present invention contains a non-white color material (A), a water-soluble organic solvent (B), a surfactant (C), and water, wherein the surfactant (C) includes an acetylenediol-based surfactant (C-1) and a silicone-based surfactant (C-2), the content of the water-soluble organic solvent (B) is more than 0 mass% and 10 mass% or less, and the weight ratio (C-1 / C-2) of the acetylenediol-based surfactant (C-1) to the silicone-based surfactant (C-2) is 0.10 or more and 0.49 or less.

[0016] [Color Material] The above ink contains a non-white coloring material. Examples of the non-white coloring material that can be used include pigments, disperse dyes, and solvent dyes. These coloring materials may be used alone, or two or more thereof may be used in combination, and for the purpose of adjusting hue or the like, two or more coloring materials having different hues can also be used in combination. From the viewpoint of image fastness such as light resistance and water resistance of recorded images, the coloring material is preferably a pigment, and the pigment is preferably an inorganic pigment, an organic pigment, or an extender pigment.

[0017] Examples of the inorganic pigments mentioned above include carbon black, metal oxides, hydroxides, sulfides, ferrocyanides, and metal chlorides. As the black pigment to be included in the black ink, carbon black such as furnace black, lamp black, acetylene black, and channel black is preferred.Specific examples of carbon black include, for example, Raven 760 ULTRA, Raven 780 ULTRA, Raven 790 ULTRA, Raven 1060 ULTRA, Raven 1080 ULTRA, Raven 1170, Raven 1190 ULTRA II, Raven 1200, Raven 1250, Raven 1255, Raven 1500, Raven 2000, Raven 2500ULTRA, Raven 3500, Raven 5000 ULTRA II, Raven 5250, Raven 5750, Raven 7000 (manufactured by Columbia Carbon); Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, and Regal 1330R, Regal 1400R, Regal 1660R, Mogul L (manufactured by Cabot); Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, SpecIal Black 4, SpecIal Black 4A, SpecIal Black 5, Special Black Examples include 6. Nerox305, Nerox505, Nerox510, Nerox600, Nerox605, NIPex180IQ, NIPex170IQ, NIPex160IQ, NIPex150IQ (manufactured by Orion Engineered Carbons); MA7, MA8, MA100, MA600, MCF-88, No.25, No.33, No.40, No.47, No.52, No.900, No.2300 (manufactured by Mitsubishi Chemical Corporation).

[0018] Examples of the above organic pigments include azo, disazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perinone, thioindigo, antholaquinone, and quinophthalone. Specific examples of organic pigments include 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, 213, etc.; 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, 272; CI Pigment Blues such as 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, 80; CI Pigment Violets such as 19, 23, 29, 37, 38, 50; CI Pigment Oranges such as 13, 16, 68, 69, 71, 73; CI Pigment Green Examples of organic pigments include greens such as 7, 36, and 54; and blacks such as CI Pigment Black 1.

[0019] Examples of the above-mentioned extender pigments include silica, calcium carbonate, talc, clay, barium sulfate, and white carbon.

[0020] Preferably, the colorants included in the above ink are, as an inorganic pigment, carbon black, and as an organic pigment, any of the following selected from the group consisting of CI Pigment Blue 15:3, 15:4, CI Pigment Yellow 74, 155, CI Pigment Red 122, 150, and CI Violet 19. More preferably, the inorganic pigment is carbon black, and the organic pigment is any of the following selected from the group consisting of CI Pigment Blue 15:4, CI Pigment Yellow 155, CI Pigment Red 122, 150, and CI Pigment Violet 19.

[0021] Specific examples of the above disperse dyes include, for example, CI Disperse Yellow 3, 4, 5, 7, 9, 13, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 114, 116, 118, 119, 122, 124, 12 6, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 184:1, 182, 183, 184, 186, 192, 198, 199, 201, 202, 204, 210, 211, 215, 216, 218, 224, 231, 232, 241 etc; CI Disperse Orange 1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 26, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 47, 48, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142 etc; CI Disperse Thread 1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151, 152, 153, 154, 157 , 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 239, 240, 257, 258, 277, 278, 279, 281, 288, 289, 298, 302, 303, 310, 311, 312, 320, 324, 328, 343, 362, 364 etc; CI Disperse Violet 1,4,8,17,23,26,27,28,31,33,35,36,38,40,43,46,48,50,51,52,56,57,59,61,63,69,77 etc;CIDisperse Green 6:1, 9 etc; CI Disperse Brown 1, 2, 4, 9, 13, 19, 26, 27 etc; CI Disperse Blue 3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 79, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 154, 158, 16 Examples include 5, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 330, 332, 333, 334, 343, 359, 360, etc.; CI Disperse Black 1, 3, 10, 24, etc.; and others.

[0022] Specific examples of the above solvent dyes include, for example, CI Solvent Yellow 2, 6, 14, 16, 21, 25, 29, 30, 33, 51, 56, 77, 80, 82, 88, 89, 93, 116, 150, 160:1, 163, 179, etc.; CI Solvent Orange 1, 2, 14, 45, 60, etc.; CI Solvent Red 1, 3, 7, 8, 9, 18, 19, 23, 24, 25, 27, 49, 100, 109, 121, 122, 125, 127, 130, 132, 135, 218, 225, 230, etc.; CI Solvent Violet 13, 31, etc.; CI Solvent Green 3, etc.; CI Solvent Brown 3, 5, etc.; CI Solvent Blue Examples include 2, 11, 14, 24, 25, 35, 36, 38, 48, 55, 59, 63, 67, 68, 70, 73, 83, 105, 111, 132, etc.: CI Solvent Black; 3, 5, 7, 23, 27, 28, 29, 34, etc.

[0023] The content of the above colorant relative to the total mass of the above ink is usually 0.5% by mass or more and 30.0% by mass or less, preferably 1.0% by mass or more and 10.0% by mass or less, more preferably 2.0% by mass or more and 7.0% by mass or less, even more preferably 3.0% by mass or more and 6.5% by mass or less, and particularly preferably 3.5% by mass or more and 6.0% by mass or less.

[0024] By setting the content of the above-mentioned colorant relative to the total mass of the above-mentioned ink to the above-mentioned range, the storage stability and printing stability of the ink, as well as the color development, abrasion resistance, and dot diameter of the printed material, can be further improved.

[0025] When using the above-mentioned pigments as colorants, one type of pigment may be used, or two or more types of pigments may be used in combination. Furthermore, two or more pigments with different hues may be used in combination for purposes such as adjusting the hue. When using two or more pigments in combination, the mixing ratio between the pigments may be adjusted according to the purpose.

[0026] [Water-soluble organic solvents] The above ink contains a water-soluble organic solvent. The water-soluble organic solvent is not particularly limited as long as it contains carbon atoms in its molecule, but specific examples include: C1-C6 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, derbutanol, and terbutanol; carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-methylpyrrolidine-2-one; cyclic ureas such as 1,3-dimethylimidazolidin-2-one and 1,3-dimethylhexahydropyrimido-2-one; ketones or ketoalcohols such as acetone, 2-methyl-2-hydroxypentan-4-one, and ethylene carbonate; and tetra Cyclic ethers such as hydrofuran and dioxane; mono, oligo, or polyalkylene glycols or thioglycols having C2-C6 alkylene units, such as ethylene glycol, diethylene glycol, propylene glycol, 1,2-butylene glycol, 1,4-butylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol (preferably with molecular weights of 400, 800, 1540 or higher), polypropylene glycol, thiodiglycol, and dithiodiglycol; C3-C9 polyols (triols) such as glycerin, diglycerin, hexane-1,2,6-triol, and trimethylolpropane;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 mono-2-ethylhexyl ether (2-ethylhexyl diglycol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol monoisobutyl ether, diethylene glycol diethyl ether, diethylene glycol monophenyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether Examples include glycol ethers such as dipropyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, proylene glycol monobutyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monopropyl ether; C5-C9 alkanediols such as 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, and 2,4-diethyl-1,5-pentanediol; γ-butyrolactone, dimethyl sulfoxide, etc. These water-soluble organic solvents may be used individually or in combination of two or more.

[0027] The above water-soluble organic solvents are preferably isopropanol, propylene glycol, 2-pyrrolidone, N-methyl-2-pyrrolidone, glycerin, triethylene glycol, ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, 1,2-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, and 2,4-diethyl-1,5-pentanediol, and more preferably contain at least one selected from the group consisting of glycerin, triethylene glycol, propylene glycol, and diethylene glycol mono-2-ethylhexyl ether.

[0028] Furthermore, it is preferable to include one or more water-soluble organic solvents having a ClogP value of 0.5 or more and 2.8 or less. The ClogP value is the logP value (partition coefficient of 1-octanol / water) calculated by means of a computer. The ClogP value can be calculated by the fragment method, the atomic approach method, etc. More specifically, to calculate the ClogP value, the fragment method described in the literature (C. Hansch and A. Leo, "Substituent Constants for Correlation Analysis in Chemistry and Biology" (John Wiley & Sons, New York, 1969)) or a commercially available software package may be used. The ClogP values ​​described in this specification were calculated using the commercially available software package Chem Draw Ultra (CambridgeSoft Corporation, USA). In this specification, the ClogP values ​​may be described to the first to third decimal places, and the least significant digit of the stated decimal number is rounded to the nearest decimal place.

[0029] As for water-soluble organic solvents with a ClogP value of 0.5 or more and 2.8 or less, there are no particular limitations as long as the solvent satisfies the conditions, but examples include diethylene glycol mono-2-ethylhexyl ether (2-ethylhexyldiglycol) (2.65), diethylene glycol monobutyl ether (0.67), diethylene glycol monoisobutyl ether (0.54), diethylene glycol diethyl ether (0.52), diethylene glycol monophenyl ether (1.25), propylene glycol monopropyl ether (0.62), proylene glycol monobutyl ether (1.15), dipropylene glycol monopropyl ether (0.75), 1,2-hexanediol (0.53), 1,2-octanediol (1.59), 2-ethyl-1,3-hexanediol (1.26), and texanol (2.74). The numbers in parentheses following the names of each water-soluble organic solvent listed above indicate their respective ClogP values.

[0030] The lower limit of the total content of the water-soluble organic solvents contained in the above ink is preferably greater than 0% by mass, more preferably 0.1% by mass or more, even more preferably 1.0% by mass or more, particularly preferably 1.5% by mass or more, extremely preferably 2.0% by mass or more, and most preferably 2.5% by mass or more. The upper limit is preferably 10.0% by mass or less, more preferably 9.5% by mass or less, even more preferably 9.0% by mass or less, particularly preferably 8.0% by mass or less, extremely preferably 7.5% by mass or less, and most preferably 7.0% by mass or less.

[0031] By keeping the total amount of water-soluble organic solvents contained in the ink within the above range, it is possible to impart wettability to the substrate to the ink while reducing the amount of organic solvents diffused into the atmosphere during printing, thereby reducing the burden on human health and the environment.

[0032] [Surfactants] The above ink contains acetylenediol-based surfactants and silicone-based surfactants.

[0033] Examples of the above-mentioned acetylenediol-based surfactants include acetylene glycol (alcohol)-based surfactants such as 2,4,7,9-tetramethyl-5-decine-4,7-diol, 3,6-dimethyl-4-octin-3,6-diol, and 3,5-dimethyl-1-hexyn-3-ol; all of which are manufactured by Nisshin Chemical Industry Co., Ltd., such as Surfinol™104PG-50(4), 420(4), 440(8), 465(13), 485(17), Dynol 604(8), and 607(8). The numbers in parentheses after each product name listed above indicate their respective HLB values.

[0034] Among the acetylene glycol-based surfactants mentioned above, it is preferable to include an acetylene glycol-based surfactant having an HLB value of 4 to 13.

[0035] The lower limit of the acetylenediol-based surfactant contained in the above ink is preferably greater than 0.05% by mass, more preferably 0.10% by mass or more, even more preferably 0.20% by mass or more, and particularly preferably 0.25% by mass or more. The upper limit is preferably 0.50% by mass or less, more preferably 0.45% by mass or less, even more preferably 0.40% by mass or less, particularly preferably 0.35% by mass or less, and extremely preferably 0.30% by mass or less.

[0036] Examples of the above-mentioned silicone-based surfactants include polyether-modified siloxanes and polyether-modified polydimethylsiloxanes. Specific examples include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-3420, BYK-3450, BYK-3455, and BYK-348. Examples include 0, BYK-3565, BYK-3760 (manufactured by Bic Chemie), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0037] The lower limit of the silicone-based surfactant contained in the above ink is preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and particularly preferably 0.8% by mass or more. The upper limit is preferably 1.2% by mass or less, more preferably 1.1% by mass or less, and particularly preferably 1.0% by mass or less.

[0038] The weight ratio of acetylenediol-based surfactant to silicone-based surfactant contained in the above ink is preferably 0.10 to 0.49, more preferably 0.20 to 0.49, more preferably 0.25 to 0.49, and particularly preferably 0.25 to 0.31.

[0039] By keeping the respective amounts and weight ratios of acetylenediol-based surfactants and silicone-based surfactants contained in the above ink within the above range, the deterioration of the water-repellent film on the inkjet head can be suppressed.

[0040] Furthermore, the above ink may contain surfactants other than the acetylenediol-based surfactant and silicone-based surfactant for purposes such as adjusting surface tension. Examples of surfactants include known surfactants such as anionic surfactants, cationic surfactants, nonionic surfactants other than acetylenediol-based surfactants, amphoteric surfactants, and fluorinated surfactants.

[0041] Examples of the above-mentioned anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acyl amino acids or their salts, N-acyl methyl taurates, alkyl sulfates, polyoxyalkyl ether sulfates, alkyl sulfates, polyoxyethylene alkyl ether phosphates, rosinic acid soaps, castor oil sulfates, lauryl alcohol sulfates, alkylphenol type phosphates, alkyl type phosphates, alkylaryl sulfonates, diethyl sulfosaturates, diethylhexyl sulfosaturates, and dioctyl sulfosaturates. Specific examples of commercially available products include, for example, Hytenol TMLA-10, LA-12, LA-16, Neo Hytenol TMECL-30S, and ECL-45, all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0042] Examples of the cationic surfactants mentioned above include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.

[0043] Examples of nonionic surfactants other than the acetylenediol-based surfactants mentioned above include ether-based surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and polyoxyethylene alkyl ether; and ester-based surfactants such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate.

[0044] Examples of the above-mentioned amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine, polyoctyl polyaminoethylglycine, and imidazoline derivatives.

[0045] Examples of the above-mentioned fluorine-based surfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carbonate compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide-containing compounds, and polyoxy ether polymer compounds having perfluoroalkyl ether groups in their side chains. Specific examples include Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300 (manufactured by DuPont); and Capstone. FS-30, FS-31, FS-3100 (manufactured by Chemors); PF-151N, PF-154N (manufactured by Omnova); F-114, F-410, F-444, EXP.TF-2066, EXP.TF-2148, EXP.TF-2149, F-430, F-477, F-552, F-553, F-554, F-555, F-556, F-5 Examples include 57, F-558, F-559, F-561, F-562, R-40, R-41, RS-72-K, RS-75, RS-76-E, RS-76-NS, RS-77, EXP.TF-1540, EXP.TF-1760 (manufactured by DIC Corporation); BYK-340, BYK-3440, BYK-3441, etc. (manufactured by Bic Chemie Japan).

[0046] These surfactants may be used individually or in combination of two or more.

[0047] If the above ink contains surfactants other than acetylenediol-based surfactants and silicone-based surfactants, it is preferable that the amount of surfactants included is within a range that does not inhibit the effects of the acetylenediol-based surfactants and silicone-based surfactants. Specifically, the amount is usually 0% to 5% by mass, preferably 0% to 4% by mass, more preferably 0% to 3% by mass, and even more preferably 0% to 1% by mass, relative to the total mass of the ink. By using surfactants within the above range in the ink composition, the penetration into the substrate and the dispersion stability of the colorant in the ink can be improved.

[0048] [water] The above ink contains water. Preferably, the water is water with a low content of impurities such as metal ions, i.e., ion-exchanged water or distilled water. The water content is typically 50% to 90% by mass, preferably 60% to 90% by mass, and particularly preferably 70% to 90% by mass, relative to the total mass of the ink according to this embodiment.

[0049] The above ink may further contain a viscosity modifier. Industrial inkjet printers typically have a defined viscosity range for the ink they can eject, based on the specifications of the printer head. Therefore, it is sometimes important to add a viscosity modifier to the ink to adjust its viscosity to an appropriate range. The viscosity modifier is not particularly limited as long as it is a substance that can adjust the viscosity of the ink; known substances can be used. Specific examples include, for example, water-soluble polymer compounds.

[0050] The viscosity range of the above ink at 25°C is typically 2.0 mPa·s to 10 mPa·s, preferably 2.0 mPa·s to 9.0 mPa·s, more preferably 3.0 mPa·s to 9.0 mPa·s, and most preferably 4.0 mPa·s to 9.0 mPa·s. The viscosity of the ink composition can be measured using a commercially available E-type viscometer, specifically the TR-100E, TV-100E, TP-200E, and RE-215 viscometers manufactured by Toki Sangyo Co., Ltd.

[0051] In addition to the above components, the above ink may optionally contain ink preparation agents such as pH adjusters, defoamers, fungicides, preservatives, chelating agents, rust inhibitors, water-soluble UV absorbers, water-soluble polymer compounds, dispersants, resin emulsions, waxes, humectants, and antioxidants.

[0052] Examples of the pH adjusting agents mentioned above include alkanolamines such as diethanolamine, triethanolamine, N-methyldiethanolamine, and 2-amino-2-methyl-1-propanol; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide (ammonia water); 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.

[0053] Examples of the above-mentioned defoaming agents include silicone-based, silica mineral oil-based, olefin-based, and acetylene-based agents. Examples of commercially available defoaming agents include Surfinol DF37, DF58, DF110D, DF220, MD-20, Orfin SK-14 (manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-1719, BYK-1724, and BYK-1770 (manufactured by Bic Chemie Japan).

[0054] Examples of the above-mentioned antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethion-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one, and their salts.

[0055] Examples of the above-mentioned preservatives include compounds such as organic sulfur, organic nitrogen sulfur, organic halogen, haloaryl sulfone, iodopropagyl, haloalkylthio, nitrile, pyridine, 8-oxyquinoline, benzothiazole, isothiazolin, dithiol, pyridine oxide, nitropropane, organotin, phenol, quaternary ammonium salt, triazine, thiazine, anilide, adamantane, dithiocarbamate, brominated indanone, benzyl bromacetate, or inorganic salts. Specific examples of organic halogen compounds include, for example, sodium pentachlorophenol; specific examples of pyridine oxide compounds include, for example, sodium 2-pyridinethiol-1-oxide; and specific examples of isothiazoline compounds include, for example, 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one magnesium chloride, 5-chloro-2-methyl-4-isothiazolin-3-one calcium chloride, and 2-methyl-4-isothiazolin-3-one calcium chloride. Specific examples of other preservatives and fungicides include anhydrous sodium acetate, sodium sorbate, or sodium benzoate, and Arch Chemical Co., Ltd. products such as Proxel GXL(S) and Proxel XL-2(S).

[0056] Examples of the chelating reagents mentioned above include disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, or sodium uracildiacetate.

[0057] Examples of the above-mentioned rust inhibitors include acidic sulfites, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitride, pentaerythritol tetranitrate, or dicyclohexylammonium nitride.

[0058] Examples of the above-mentioned water-soluble ultraviolet absorbers include sulfonated benzophenone compounds, benzotriazol compounds, salicylic acid compounds, cinnamic acid compounds, or triazine compounds.

[0059] Examples of the above-mentioned water-soluble polymer compounds include polyethylene glycol, polyvinyl alcohol, cellulose derivatives, polysaccharides, polyamines or polyimines, and neutralized aqueous solutions of styrene-acrylic copolymers.

[0060] The above dispersant is not particularly limited, and known dispersants can be used. Known dispersants include, for example, copolymers composed of at least two monomers (preferably at least one of which is hydrophilic) selected from monomers of the group consisting of styrene and its derivatives; vinylnaphthalene and its derivatives; aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids; acrylic acid and its derivatives; maleic acid and its derivatives; itaconic acid and its derivatives; fahric acid and its derivatives; vinyl acetate, vinyl alcohol, vinylpyrrolidone, acrylamide, and their derivatives. Examples of such copolymers include styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, (meth)acrylic acid ester-(meth)acrylic acid copolymer, polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymer, styrene-maleic acid copolymer, and the like.

[0061] Among these, styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, (meth)acrylic acid ester-(meth)acrylic acid copolymer, and polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymer are preferred; styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, and (meth)acrylic acid ester-(meth)acrylic acid copolymer are more preferred; (meth)acrylic acid ester-(meth)acrylic acid copolymer is even more preferred; and methacrylic acid ester-methacrylic acid copolymer is particularly preferred.

[0062] Examples of copolymer types include block copolymers, random copolymers, graft copolymers, and / or salts thereof, with block copolymers being preferred.

[0063] Dispersants can be synthesized or obtained commercially. Specific examples of commercially available dispersants include styrene-acrylic copolymers such as Joncryl 62, 67, 68, 678, and 687, all manufactured by BASF; Movinyl S-100A (modified vinyl acetate copolymer manufactured by Hoechst Synthetic Co., Ltd.); and Jurimer AT-210 (polyacrylic acid ester copolymer manufactured by Nippon Junyaku Co., Ltd.). As a block copolymer obtained by synthesis, the AB block polymer disclosed in International Publication No. 2013 / 115071 is a preferred example. These dispersants may be used individually or in combination of two or more.

[0064] The above-mentioned resin emulsion is not particularly limited as long as it is different from the above-mentioned dispersant, and examples include urethane resins, polyester resins, acrylic resins, vinyl acetate resins, vinyl chloride resins, acrylic styrene resins, acrylic silicone resins, etc. Specific examples of resin emulsions include, for example, Superflex 126, 150, 170, 210, 420, 470, 820, 830, 860, 890 (urethane-based resin emulsion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.); Hydran HW-350, HW-178, HW-163, HW-171, AP-20, AP-30, AP-40F, WLS-201, WLS-210 (urethane-based resin emulsion, manufactured by DIC Corporation); 0569, 0850Z, 2108 (styrene-butadiene-based resin emulsion). Examples include: JSR Corporation's AE980, AE981A, AE982, AE986B, AE104 (acrylic resin emulsion, manufactured by E-Tech Co., Ltd.), Saibinol SK-200 (acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.), Boncoat 4001, Boncoat 5454 (acrylic resin emulsion, manufactured by DIC Corporation), etc. When the above ink composition contains the above resin emulsion, the proportion of solid content of the above resin emulsion in the above ink composition is usually 0.1% to 10.0% by mass, preferably 0.3% to 9.0% by mass, more preferably 0.5% to 8.0% by mass, even more preferably 1.0% to 8.0% by mass, and most preferably 1.5% to 8.0% by mass.

[0065] As the above waxing agent, a wax emulsion is preferred, and a water-based wax emulsion is more preferred. Natural waxes and synthetic waxes can be used as waxing agents. Examples of natural waxes include petroleum-based waxes such as paraffin wax and microcrystalline wax; lignite-based waxes such as montane wax; plant-based waxes such as carnauba wax and candelilla wax; and emulsions in which waxes such as beeswax and lanolin are dispersed in an aqueous medium. Examples of synthetic waxes include polyalkylene wax (preferably poly C2-C4 alkylene wax), oxidized polyalkylene wax (preferably oxidized poly C2-C4 alkylene wax), and paraffin wax. Of the above, one or more waxes selected from polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, and paraffin wax are preferred, and oxidized polyethylene wax is more preferred. In addition, the average particle size of the wax is 50 nm to 5 μm, and preferably 100 nm to 1 μm, in order to prevent clogging of the inkjet head. Examples of commercially available wax emulsions include AQUACER 515 (acid value: 5) manufactured by BIC Chemie Japan, and HYTEC E-6500 (acid value: 10-20) manufactured by Toho Chemical Industry Co., Ltd. When the above-mentioned wax is included in the above-mentioned ink composition, the solid content ratio of the above-mentioned wax agent in the above-mentioned ink composition is usually 0.1% to 5% by mass, preferably 0.2% to 3% by mass, more preferably 0.5% to 3% by mass, even more preferably 0.5% to 2% by mass, and most preferably 0.5% to 1.5% by mass.

[0066] The above-mentioned humectants are preferably miscible with water and provide an effect of preventing blockage of the inkjet head ejection port and resolubility. Solid humectants can also be used. Solid humectants are suitable for inkjet ink compositions because they can hold more water than liquid humectants. Examples include ethylene carbonate, urea, ethylene urea, dimethylethylene urea, acetamide, and ε-caprolactam. Among these, water-soluble solid humectants (hereinafter referred to as "water-soluble solid humectants") are preferred. Water-soluble solid humectants are used to prevent the drying of water-based inkjet ink at the ejection nozzles of the inkjet head.

[0067] As the above-mentioned water-soluble solid humectant, it is preferable to use a sugar alcohol from the viewpoint of humectancy and solubility in water. A sugar alcohol is a compound formed by reducing a sugar compound (e.g., aldoses and ketoses). Sugar alcohols have a large number of hydroxyl groups and therefore have excellent solubility in water. Sugar alcohols have a melting point of 25°C or higher. Therefore, sugar alcohols are solid at room temperature. The melting point of sugar alcohols is usually 25°C to 270°C, preferably 50°C to 250°C, more preferably 50°C to 200°C, even more preferably 50°C to 170°C, and most preferably 50°C to 150°C. By using sugar alcohols within this melting point range, images with excellent fixability, drying properties, abrasion resistance, and transfer prevention at room temperature can be obtained. Examples of sugar alcohols include threitol (melting point 88-90°C), erythritol (melting point 121°C), arabitol (melting point 103°C), ribitol (melting point 102°C), xylitol (melting point 92-96°C), sorbitol (glucitol) (melting point 95°C), mannitol (melting point 164-169°C), iditol (melting point 75-79°C), galactitol (melting point 186-191°C), allitol (melting point 150-154°C), maltitol (melting point 145°C), isomaltitol (melting point 98-103°C), lactitol (melting point 146°C), pentaerythritol (melting point 190-263°C), etc. One of these can be used alone or two or more can be used in combination, and among these, sorbitol (glucitol) is particularly preferred.

[0068] Furthermore, the above sugar alcohol may contain impurities such as glucose (grape sugar) before reduction.

[0069] The content of the sugar alcohol relative to the total mass of the ink is usually 1.0% by mass or more and 15% by mass or less, preferably 2.0% by mass or more and 15% by mass or less, more preferably 2.0% by mass or more and 12% by mass or less, even more preferably 3.0% by mass or more and 12% by mass or less, particularly preferably 5.0% by mass or more and 12.0% by mass or less, and most preferably 6.0% by mass or more and 12.0% by mass or less.

[0070] By including sugar alcohols within the above range, it becomes possible to achieve a good balance between redispersibility, drying properties on the substrate, and transfer prevention.

[0071] As the above-mentioned antioxidant, for example, various organic and metal complex-based colorfastness inhibitors can be used. Examples of the above-mentioned organic colorfastness inhibitors include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, or heterocyclic compounds.

[0072] The above ink can be used in various printing applications. For example, it is suitable for writing instruments, various types of printing, information printing, and textile printing, and is particularly preferred for use in inkjet printing.

[0073] When preparing the above-mentioned ink, known manufacturing methods can be used. For example, one method involves preparing an ink by adding a water-soluble organic solvent, an acetylene glycol-based surfactant, a silicone-based surfactant, water, and, if necessary, an ink preparing agent to an aqueous dispersion prepared from a colorant, a dispersant, and water, and then mixing the mixture.

[0074] The above ink can be prepared using conventionally known equipment, such as a ball mill, sand mill, attritor, basket mill, roll mill, or agitator. During preparation, it is preferable to remove coarse particles using a membrane filter or mesh filter.

[0075] An ink set containing at least the above-mentioned inks is also included in the present invention. Examples of the above-mentioned ink sets include an ink set containing two or more of the above-mentioned inks, an ink set containing one or more of the above-mentioned inks and one or more of other inks. The other inks other than the above-mentioned inks are not particularly limited as long as their composition is different from the above-mentioned inks, but it is preferable that they have a different hue from the above-mentioned inks.

[0076] The above ink and ink set are preferably used in inkjet printing.

[0077] The present invention also includes an inkjet recording method that includes the step of ejecting droplets of the above-mentioned ink and adhering them to a printing medium to form an image.

[0078] When using the above ink for inkjet recording, it is preferable to remove aggregates and other contaminants by filtering the ink. Any known filtration method can be used as appropriate. For example, a method using suction filtration with filter paper such as glass filter paper GC-50 (retaining particle diameter 0.5 μm, manufactured by Advantec Co., Ltd.) or glass filter paper GA-100 (retaining particle diameter 1.0 μm, manufactured by Advantec Co., Ltd.) is possible.

[0079] The above-mentioned printing media refers to a medium (media) to which the above-mentioned ink can adhere, and can be broadly classified into those that absorb ink and those that do not absorb ink. Examples of ink-absorbing printing media include inkjet paper, inkjet film, glossy paper, corrugated cardboard, and liner paper contained in corrugated cardboard, etc. Specific examples of liner paper include K-liner, C-liner, and lightweight liner manufactured by Oji Materia Co., Ltd., Nippon Paper Industries Ltd., and Daio Paper Corporation, among others.

[0080] Examples of low-absorption printing media include various types of paper used in gravure printing and offset printing, such as coated paper, lightweight coated paper, lightly coated paper, coated cardboard, and art paper, as well as cast coated paper used for label printing. These low-absorption printing media are formed by applying a coating agent to untreated high-quality paper to provide whiteness and other properties, creating a coating layer. Specific examples include OK Topcoat+, Mirrorcoat Platinum (manufactured by Oji Paper Co., Ltd.), Auroracoat (manufactured by Nippon Paper Industries Ltd.), Pearlcoat (manufactured by Mitsubishi Paper Mills Ltd.), Maricoat (manufactured by Hokuetsu Corporation), and Raichocoat (manufactured by Chuetsu Pulp & Paper Co., Ltd.).

[0081] The above inks can be applied to any printing medium, but are particularly suitable for use on liner paper and poorly absorbent printing media.

[0082] When using these ink-poor ink-absorbing printing media, it is also preferable to apply a surface modification treatment to the printing media in order to improve the fixation of the colorants.

[0083] As a method of surface modification, it is preferable to perform at least one treatment selected from corona discharge treatment, plasma treatment, and flame treatment. Known methods can be used for these treatments. Furthermore, it is generally known that the effect of surface modification based on these treatments weakens over time. For this reason, when surface modification is performed on a poor-absorption media, it is preferable to perform inkjet recording as soon as possible. Surface modification of poorly absorbent media can be performed by appropriately adjusting the number of treatments, treatment time, and applied voltage, etc., to obtain the desired effect. The state of surface modification can be confirmed by measuring the contact angle using known methods.

[0084] The above ink exhibits excellent wetting and spreading properties on poorly absorbent media, and high-density printed images can be obtained even on liner paper. This ink is extremely useful for various printing applications, especially inkjet printing.

[0085] The above inkjet recording method involves ejecting droplets of each ink from the above ink set from an inkjet printer in accordance with a recording signal and adhering them to a printing medium to perform recording. There are no particular restrictions on the ink nozzles used during recording, and they can be appropriately selected according to the purpose.

[0086] Inkjet printers can use any known recording method. Examples include charge control methods that use electrostatic attraction to eject ink; drop-on-demand methods (pressure pulse methods) that use the vibration pressure of a piezoelectric element; acoustic inkjet methods that convert electrical signals into acoustic beams, irradiate ink onto it, and eject ink using the resulting radiation pressure; and thermal inkjet methods that heat the ink to form bubbles and utilize the resulting pressure. Furthermore, the inkjet recording method of the present invention also includes methods that improve the fixation of colorants by using colorless, transparent ink.

[0087] Industrial inkjet printers, in order to achieve high printing speeds, are configured as line-head inkjet printers, and single-pass printing is also preferred. With the above-mentioned ink, good quality prints can be obtained even under such printing conditions.

[0088] The above-described inkjet recording method is a method of recording using an inkjet printer having a container containing the above-described ink, and the inkjet recording method is preferably one in which the printing medium is selected from the group consisting of corrugated cardboard, liner paper, coated cardboard, and coated paper, with corrugated cardboard, liner paper, and coated cardboard being particularly preferred. A recording method in which the printing medium is an ink-poor absorbent medium is also preferred.

[0089] Unless otherwise specified, for all the matters mentioned above, a combination of preferred elements is more preferable, and a combination of preferred elements is even more preferable. The same applies to combinations of preferred elements and preferred elements, and combinations of preferred elements and even more preferable elements. Furthermore, unless otherwise specified, all of the above-mentioned ingredients may be used individually or in combination of two or more elements.

[0090] The ink of the present invention exhibits excellent water repellency on the nozzle plate, minimal erosion of the nozzle plate, excellent storage stability, and reliable ejection. Furthermore, images recorded with the ink exhibit excellent color development and saturation, as well as superior durability in various aspects such as heat resistance, transferability, water resistance, light resistance, heat resistance, oxidation gas resistance (e.g., ozone gas resistance), and abrasion resistance. In addition, it exhibits excellent image formation performance due to its drying properties during image formation, minimal coating unevenness and bleeding, and large dot diameter.

[0091] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by the following examples. The colorant content in the total mass of the dispersion was calculated using the dry weight method with MS-70, manufactured by A&D Co., Ltd., and was converted to a value representing only the colorant content.

[0092] [Preparation Example 1]: Preparation of cyanide dispersion A block copolymer described in Synthesis Example 3 of International Publication No. 2013 / 115071 was prepared, and the obtained block copolymer (6 parts) was dissolved in 20 parts methyl ethyl ketone to obtain a homogeneous solution. A mixture of sodium hydroxide (0.45 parts) dissolved in water (53.55 parts) was added to this solution, and then 20 parts of CIPigment Blue 15:4 (manufactured by Dainichi Seika Co., Ltd., Chromofine blue 4851) was added. The mixture was dispersed in a sand grinder under 1500 rpm conditions for 15 hours to obtain a liquid. After adding water (100 parts) to the obtained liquid, aggregates and other contaminants were removed by filtration using glass filter paper GA-100 to obtain a filtrate. The obtained filtrate was subjected to vacuum distillation of the methyl ethyl ketone and a portion of the water using an evaporator, so that the pigment content in the filtrate was 12.0%, thereby obtaining a cyanide dispersion (Cdp).

[0093] [Preparation Example 2]: Preparation of resin emulsion. By replicating Preparation Example 4 of International Publication No. 2015 / 147192, a resin emulsion with an acid value of 6 mg KOH / g and a solid content of 25% was prepared. This was designated as Resin 1.

[0094] [Examples 1-9 and Comparative Examples 1-4: Preparation Examples of Ink Compositions] After mixing the components listed in Tables 1 and 2 below, each ink composition for evaluation testing was obtained by filtering the mixture through a 3 μm membrane filter.

[0095] The abbreviations in Tables 1 and 2 below represent the following: Cdp: Cyanide dispersion obtained in Preparation Example 1. PnB: Propylene glycol monobutyl ether. 1,2HD: 1,2-Hexanediol. EHDG: Diethylene glycol mono-2-ethylhexyl ether. TEG: Triethylene glycol. CD: α-cyclodextrin. TEA: Triethanolamine. SF420: Surfinol 420 (Manufactured by Nisshin Chemical Industry Co., Ltd.) SF440: Surfinol 440 (Manufactured by Nisshin Chemical Industry Co., Ltd.) SF465: Surfinol 465 (manufactured by Nisshin Chemical Industry Co., Ltd.) BYK-349: BYK-349. (Manufactured by Big Chemie Japan Co., Ltd.) BYK-3420: BYK-3420. (Manufactured by Big Chemie Japan Co., Ltd.) Resin 1: Resin emulsion obtained in Preparation Example 2. Waxing agent: Hi-Tec E6314 (wax emulsion manufactured by Toho Chemical Industry Co., Ltd., solid content 35%) Water: Deionized water.

[0096] [Changes in water repellency of nozzle plates over time] A 0.5 cm square silicone nozzle plate was immersed in the ink composition of each example and comparative example, and the samples were stored at 60°C for one week to obtain test specimens. The contact angle of water was measured on the obtained test specimens using a contact angle meter. The contact angle was measured using the droplet method with a DMI-501Hi manufactured by Kyowa Interface Science Co., Ltd. Specifically, a 2 μL droplet of water was dropped onto the test piece, and the contact angle was measured at 25°C 1 second after dropping. The obtained values ​​were rounded to the nearest whole number and evaluated according to the following four evaluation criteria A to D. A higher contact angle indicates less loss of water repellency and less erosion of the silicone plate. The evaluation results for each example and comparative example are shown in Tables 1 and 2 below. [Evaluation Criteria] A: 90° or more B: 85° or more and less than 90° C: 80° to less than 85° D: Less than 80°

[0097] [Table 1]

[0098] [Table 2]

[0099] From the results in Tables 1 and 2 above, it was found that the example ink has the effect of maintaining the water-repellent properties of the nozzle plate. [Industrial applicability]

[0100] As described above, the aqueous ink composition of the present invention exhibits minimal erosion of the water-repellent film and good suitability for inkjet heads. For this reason, the ink of the present invention is extremely useful as an aqueous ink for inkjet recording.

Claims

1. A water-based ink composition comprising a non-white colorant (A), a water-soluble organic solvent (B), a surfactant (C), and water, wherein the surfactant (C) comprises an acetylenediol-based surfactant (C-1) and a silicone-based surfactant (C-2), the content of the water-soluble organic solvent (B) is greater than 0% by mass and 10% by mass or less, and the weight ratio (C-1 / C-2) of the acetylenediol-based surfactant (C-1) to the silicone-based surfactant (C-2) is 0.10 or more and 0.49 or less.

2. The aqueous ink composition according to claim 1, wherein the content of the silicone-based surfactant (C-2) is 0.5% by mass or more.

3. The aqueous ink composition according to claim 1, wherein the HLB value of the acetylenediol-based surfactant (C-1) is 4 or more and 13 or less.

4. The aqueous ink composition according to claim 1, wherein the water-soluble organic solvent (B) comprises one or more organic solvents having a ClogP value of 0.5 or more and 2.8 or less.

5. The aqueous ink composition according to claim 1, wherein the non-white colorant (A) is a pigment.

6. Furthermore, the aqueous ink composition according to claim 1 further contains a humectant (D).

7. The aqueous ink composition according to claim 6, wherein the humectant (D) is a sugar alcohol.

8. The aqueous ink composition according to claim 7, wherein the sugar alcohol is sorbitol.

9. A method for producing an inkjet printed material, comprising ejecting droplets of the aqueous ink composition described in claim 1 from an inkjet head and adhering them to a printing medium to obtain a printed material.

10. The method for manufacturing an inkjet printed article according to claim 9, wherein the printing medium is at least one selected from the group consisting of corrugated cardboard, liner paper, and coated cardboard.

11. The method for manufacturing an inkjet printed material according to claim 9, wherein the printing medium is coated paper.

12. A method for manufacturing an inkjet printed material, comprising: a printing step of ejecting droplets of the aqueous ink composition described in claim 1 from an inkjet head in a single-pass manner and adhering them to liner paper or coated cardboard to obtain a printed material; and a lamination step of bonding the printed material to a core to obtain a corrugated cardboard sheet, performed in succession.

Images