Method for using ink, ink set, inkjet ink composition, and method for producing same

Abstract

Provided are a method for using an ink, an ink set, an inkjet ink composition, and a method for producing the same, which can reduce environmental load during transport and storage space compression during ink storage, and enable the storage of a dry ink composition to be good. An inkjet ink composition obtained by adding a liquid medium to a dry ink composition has good resolubility / redispersibility and intermittent printing stability. An ink composition (A) containing a colorant and a water-soluble substance that is solid at 25 DEG C and one standard atmospheric pressure, and an aqueous solution (B) containing a water-soluble substance that is solid at 25 DEG C and one standard atmospheric pressure, are mixed when used in an ink jet printer to obtain an ink jet ink composition (C) having a surface tension of 40 mN / m or less after mixing and a viscosity of 100 mPa * s or less, and the ink composition (C) is discharged from the ink jet printer to be used, and the ink composition (B) containing a colorant and a water-soluble substance that is solid at 25 DEG C and one standard atmospheric pressure. The content of a substance that is liquid in an environment of 25 DEG C and one standard atmospheric pressure is 20% by mass or less with respect to the total amount of the ink composition A. The aqueous solution B contains 50% by mass or more of water with respect to the total amount of the aqueous solution B.

Description

Technical Field

[0001] The present invention relates to a method for using an ink, an ink set, a method for producing an inkjet ink composition, and an inkjet ink composition. Background Art

[0002] Inkjet recording methods, which enable recording of high-definition images using relatively simple equipment, are experiencing rapid development in various fields. Among these, research is underway into the use of ink compositions from which at least a portion of the liquid medium has been removed (dry ink compositions).

[0003] For example, Patent Document 1 describes a method for producing an inkjet recording ink, comprising: step I, a step of mixing and dispersing water, a pigment, a resin (A'), and a neutralizing agent (B) to obtain an aqueous pigment dispersion (D); step II, a step of drying the aqueous pigment dispersion (D) obtained in step I to obtain a pigment-containing resin composition having a volatile matter content of 1% by mass or less; and step III, a step of mixing the pigment-containing resin composition obtained in step II with a liquid compound to obtain an inkjet recording ink.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-045469

[0005] However, conventional methods have failed to reduce the environmental load during transportation caused by the weight of the ink medium components, nor have they reduced the storage space pressure during ink storage. Furthermore, they have failed to improve the storability of the dried ink composition, nor have they improved the resolubility / redispersibility of the inkjet ink composition obtained by adding a liquid medium to the dried ink composition, nor have they improved intermittent printing stability. Summary of the Invention

[0006] According to one embodiment of the method for using the ink of the present invention,

[0007] The ink composition A and the aqueous solution B are mixed when used in an inkjet printer to obtain an inkjet ink composition C having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less after mixing, and the inkjet ink composition C is ejected from the inkjet printer for use.

[0008] The ink composition A comprises a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A.

[0009] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B.

[0010] According to one embodiment of the ink set according to the present invention,

[0011] The ink set includes:

[0012] Ink composition A, comprising a colorant, a water-soluble substance that is solid at 25°C and 1 standard atmosphere, and a liquid substance at 25°C and 1 standard atmosphere, wherein the content of the liquid substance is 20% by mass or less relative to the total amount of ink composition A; and

[0013] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B,

[0014] The ink set is prepared by mixing the ink composition A and the aqueous solution B so that the surface tension is 40 mN / m or less and the viscosity is 100 mPa·s or less.

[0015] According to one embodiment of the method for producing an inkjet ink composition according to the present invention,

[0016] The method for producing the inkjet ink composition comprises the steps of mixing the ink composition A and the aqueous solution B when used in an inkjet printer.

[0017] The ink composition A comprises a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A.

[0018] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B,

[0019] The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0020] According to one embodiment of the inkjet ink composition of the present invention,

[0021] The inkjet ink composition comprises an ink composition A and an aqueous solution B,

[0022] The ink composition A comprises a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A.

[0023] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B,

[0024] The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram for explaining the structure of an inkjet head that can be used in this embodiment.

[0026] Figure 2 This is a perspective view showing a serial inkjet device according to this embodiment.

[0027] Figure 3 Table 1 shows composition examples of ink before drying.

[0028] Figure 4 Table 2 shows an example of the composition of the ink after drying.

[0029] Figure 5 Table 3 shows composition examples of aqueous solutions.

[0030] Figure 6 Table 4 describes the conditions and evaluation results of each example.

[0031] Figure 7 Table 5 describes the conditions and evaluation results of each example.

[0032] Description of Reference Numerals

[0033] 1: nozzle; 2: pressure chamber; 3: circulation path; 4: communication path; 10, 231: inkjet head; 20: serial printer; 220: conveying unit; 230: recording unit; 234: carriage; 235: carriage moving mechanism; F: recording medium; S1, S2: main scanning direction; T1: sub-scanning direction. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention. The embodiments described below are provided as examples to illustrate the present invention. The present invention is not limited to the following embodiments and includes various modifications that are implemented without changing the gist of the present invention. In addition, not all of the components described below are necessarily essential components of the present invention.

[0035] In this specification, the numerical range expressed using “~” means a range including the numerical values ​​described before and after “~” as the lower limit and the upper limit.

[0036] 1. How to use ink

[0037] A method for using an ink according to one embodiment of the present invention comprises mixing an ink composition A and an aqueous solution B during use in an inkjet printer to obtain an inkjet ink composition C having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less after mixing, and ejecting the obtained inkjet ink composition C from the inkjet printer for use. The ink composition A comprises a colorant, a water-soluble substance that is solid at 25°C and 1 standard atmosphere, and a substance that is liquid at 25°C and 1 standard atmosphere, wherein the content of the substance is 20% by mass or less relative to the total amount of the ink composition A. The aqueous solution B comprises 50% by mass or more of water relative to the total amount of the aqueous solution B.

[0038] Conventional methods do not mix the ink immediately before use in an inkjet printer, thus failing to reduce the environmental impact of transportation and storage space. In contrast, the method of this embodiment, which mixes the dry ink composition and the aqueous solution to form the inkjet ink just before use in the inkjet printer, can minimize the environmental impact of transportation and storage space. For example, if an aqueous solution containing 50% or more water is prepared for use in the printer, the environmental impact of transportation and storage space can be more effectively reduced.

[0039] Furthermore, the dry ink composition, containing a colorant and a water-soluble solid substance, improves redissolubility and redispersibility. The aqueous solution, containing 50% or more water by mass relative to the total amount of the aqueous solution, improves intermittent printing stability. Furthermore, by setting the surface tension and viscosity of the mixed inkjet ink composition to predetermined values, stable inkjet discharge can be achieved.

[0040] Hereinafter, each step of the method according to this embodiment will be described.

[0041] 1.1 Ink composition A preparation process

[0042] The method for using the ink according to this embodiment includes an ink composition A preparation step of preparing the ink composition A. Hereinafter, various components contained in the ink composition A will be described.

[0043] Ink composition A contains a colorant and a water-soluble substance that is solid at 25°C and 1 standard atmosphere. The content of the substance that is liquid at 25°C and 1 standard atmosphere is 20% by mass or less relative to the total amount of ink composition A. This improves redissolubility, redispersibility, and storage properties.

[0044] 1.1.1 Color materials

[0045] The ink composition A contains a coloring material. Examples of the coloring material include dyes and pigments.

[0046] dye

[0047] Examples of the dye include acid dyes, direct dyes, reactive dyes, basic dyes, and disperse dyes.

[0048] The yellow dye is not particularly limited, and examples thereof include CI Acid Yellow 1, 3, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 59, 61, 70, 72, 75, 76, 78, 79, 98, 99, 110, 111, 127, 131, 135, 142, 162, 164, and 165; CI Direct Yellow 1, 8, 11, 12, 24, 26, and 27; , 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 110, 132, 142, 144, 162, 165; CI Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, 42; CI Food Yellow 3, 4; CI Solvent Yellow 15, 19, 21, 30, 109.

[0049] Magenta dyes are not particularly limited, and examples thereof include CI Acid Red 1, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42, 51, 52, 57, 75, 77, 80, 82, 85, 87, 88, 89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165 31, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184, 186, 194, 198, 209, 211, 215, 219, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321, 322; CI Direct Red 1, 2 , 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231; CI Reactive Red 1, 2, 3 , 4, 5, 6, 7, 8, 11, 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 49, 50, 58, 59, 63, 64, 245; CI Solvent Red 1; CI Food Red 7, 9, 14.

[0050] Examples of cyan dyes include CI Acid Blue 1, 7, 9, 15, 22, 23, 25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78, 80, 82, 83, 90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154, 158, 161, 166, 167, 168, 170, 171, 182, 183, 184, 187, 192, 199, 203, 204, 205, 229, 234, 236, 249; CI Direct Blue 1, 2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, 249; CI Reactive Blue 1, 2, 3, 4, 5 , 7, 8, 9, 13, 14, 15, 15:1, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33, 34, 37, 38, 39, 40, 41, 43, 44, 46; CI Solvent Blue 1, 5, 41; CI Vat Blue 4, 29, 60; CI Food Blue 1, 2; CI Basic Blue 9, 25, 28, 29, 44.

[0051] Examples of orange dyes include acid orange 3, 7, 8, 10, 19, 22, 24, 33, 45, 51, 51S, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166, and 168; Reactive Orange 1, 2, 4, 5, 7, 11, 12, 13, 15, 16, 20, 30, 35, 56, 64, 67, 69, 70, 72, 74, 82, 84, 86, 87, 91, 92, 93, 95, 107.

[0052] Examples of black dyes include acid black 1, 2, 7, 24, 26, 29, 31, 44, 48, 50, 51, 52, 52:1, 58, 60, 62, 63, 64, 67, 72, 76, 77, 94, 107, 108, 109, 110, 112, 115, 118, 119, 121, 122, 131, 132, 139, 140, 155, 156, 157, 158, 159, 172, 191, 192 4, 207, 234; Direct Black 9, 17, 19, 22, 32, 51, 56, 62, 69, 77, 80, 91, 94, 97, 108, 112, 113, 114, 117, 118, 121, 122, 125, 132, 146, 154, 166, 168, 173, 195, 199; Reactive Black 1, 3, 4, 5, 7, 8, 11, 12, 14, 17, 21, 23, 26, 31, 32, 34, 39.

[0053] The above dyes may be used alone or in combination of two or more.

[0054] pigment

[0055] As the pigment, for example, inorganic pigments including carbon black and titanium white, organic pigments, and the like can be used.

[0056] As inorganic pigments, carbon blacks such as CI Pigment Black 6 (lamp black, vegetable carbon black), CI Pigment Black 7 (furnace black, channel black, thermal black, acetylene black), CI Pigment Black 8 (charcoal black), and CI Pigment Black 10 (graphite black), iron oxide, titanium oxide, zinc oxide, and silica can be used.

[0057] Examples of carbon black include No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No. 2200B manufactured by Mitsubishi Chemical Corporation. Examples include Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, and Special Black 6, 5, 4A, 4, and 250 manufactured by Degussa. Examples include Conductive Black SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, and 700 manufactured by Columbia Carbon. Examples include Rega1 400R, 330R, 660R, Mogul L, Monarch700, 800, 880, 900, 1000, 1100, 1300, 1400, and ELFTEX 12 produced by Cabot.

[0058] Examples of organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthrone pigments, indanone pigments, flavanone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.

[0059] Specific examples of the organic pigment used in the ink composition A include the following pigments.

[0060] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, and 60; and CI Vat Blue 4 and 60. Preferably, one or a mixture of two or more selected from the group consisting of CI Pigment Blue 15:3, 15:4, and 60 can be used.

[0061] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122, 123, 168, 184, and 202; and CI Pigment Violet 19. Preferred examples include one or a mixture of two or more selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI 19 Pigment Violet. Solid solutions of these pigments are also possible.

[0062] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, and 185. Preferably, one or a mixture of two or more selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, 138, 155, and 180 can be used.

[0063] Examples of orange pigments include CI Pigment Orange 36 or 43, or mixtures thereof. Examples of green pigments include CI Pigment Green 7 or 36, or mixtures thereof.

[0064] Furthermore, bright pigments can also be used. These pigments are not particularly limited as long as they exhibit a bright appearance when attached to a medium. Examples include metal microparticles of alloys of one or more selected from the group consisting of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper (also known as metallic pigments), and pearlescent pigments with a pearlescent luster. Representative examples of pearlescent pigments include titanium dioxide-coated mica, fish scale foil, and bismuth chloride, which exhibit pearlescent or interference luster. Furthermore, bright pigments must not be surface-treated to inhibit reactivity with water.

[0065] Furthermore, white pigments may be used, for example, metal compounds such as metal oxides, barium sulfate, and calcium carbonate. Examples of metal oxides include titanium dioxide, zinc oxide, silicon dioxide, aluminum oxide, and magnesium oxide. Furthermore, white pigments may also be made of microparticles having a hollow structure.

[0066] The above-mentioned pigments may be used alone or in combination of two or more. From the viewpoint of storage stability such as light resistance, weather resistance, and gas resistance, the pigment is preferably an organic pigment.

[0067] Regarding the volume average particle size (D50) of the pigment, the volume average particle size (D50) when measured by a dynamic light scattering method is 20 nm or more and 300 nm or less, more preferably 30 nm or more and 200 nm or less, and even more preferably 40 nm or more and 100 nm or less.

[0068] The volume average particle size can be measured, for example, using a NANOTRAC series particle size distribution measuring instrument manufactured by MICROTRACBEL. Examples of methods for adjusting the volume average particle size include adjusting the degree of pigment pulverization before dispersion, adjusting the particle size based on stirring conditions during dispersion (e.g., stirring speed, stirring temperature, etc.), and adjusting the particle size by filtering after dispersion.

[0069] Furthermore, in order to improve the dispersibility of the pigment in the inkjet ink composition, it is preferable to perform surface treatment on the pigment or to mix a dispersant with the pigment.

[0070] The surface treatment of the pigment is preferably a treatment in which carbonyl groups, carboxyl groups, aldehyde groups, hydroxyl groups, sulfonyl groups, ammonium groups, and functional groups consisting of salts thereof are directly or indirectly bonded to the surface of the pigment by physical or chemical treatment. In particular, the surface treatment is more preferably a treatment in which the surface of the pigment particles is modified by oxidation or sulfonation of the pigment surface using ozone, hypochlorous acid, fuming sulfuric acid, or the like.

[0071] When preparing a dispersant for ink composition A, it is preferred to use one with a hydrophobic portion (hydrophobic group) and a hydrophilic portion (hydrophilic group) in its molecular structure. Such a dispersant has the effect of causing the hydrophobic portion to adsorb onto the surface of pigment particles, while the hydrophilic portion is oriented toward the aqueous medium side of the inkjet ink composition. This effect tends to stabilize the pigment dispersion within the inkjet ink composition.

[0072] Such dispersants are not particularly limited. Examples include acrylic resins, styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylate copolymers and other styrene-acrylic acid resins, styrene-maleic acid resins, and salts thereof, and formaldehyde condensates of aromatic sulfonates. At least one selected from the group consisting of these substances can be used. Commercially available dispersants can also be used.

[0073] When the pigment is dispersed by a dispersant, the ratio of the pigment to the dispersant is preferably 10:1 to 1:10, more preferably 4:1 to 1:3.

[0074] Alternatively, a method of imparting dispersibility by coating pigment microparticles with a resin, etc. Examples of methods for coating pigment microparticles include an acid precipitation method, a phase inversion emulsification method, and a microemulsion polymerization method.

[0075] The coloring material contained in the ink composition A is preferably a water-soluble coloring material. In the case of a water-soluble coloring material, the re-dissolubility and re-dispersibility when used as an inkjet ink composition tend to be better.

[0076] The "water solubility" of a color material means that at least a portion of the color material dissolves in water at 20°C. The solubility in water at 20°C is preferably greater than 1 g / 100 g of water, more preferably greater than 3 g / 100 g of water, and particularly preferably greater than 5 g / 100 g of water.

[0077] Examples of the water-soluble coloring material include acid dyes, direct dyes, reactive dyes, and basic dyes.

[0078] The coloring material contained in the ink composition A is preferably a dye. When the coloring material is a dye, the redissolubility and redispersibility when prepared as an inkjet ink composition tend to be better.

[0079] The colorant contained in ink composition A is preferably a reactive dye. Reactive dyes undergo hydrolysis in water, resulting in the inactivation of the reactive groups contained in the reactive dye. In contrast, the method according to this embodiment mixes the ink composition A with a liquid medium immediately before use in an inkjet printer. This tends to reduce the inactivation of reactive groups and achieve excellent dyeability.

[0080] The content of the colorant is preferably 35% by mass or less, more preferably 30% by mass or less, and particularly preferably 25% by mass or less, relative to the total amount of ink composition A. When the colorant content is within this range, the inkjet ink composition tends to have better redissolubility and redispersibility.

[0081] The lower limit of the color material content is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and particularly preferably 20% by mass or more, relative to the total amount of the ink composition A.

[0082] 1.1.2 Water-soluble solids

[0083] Ink composition A contains a substance that is water-soluble and solid at 25°C and 1 standard atmosphere (hereinafter referred to as a "water-soluble solid substance"). The "water solubility" of the water-soluble solid substance is the same as the "water solubility" of the color material described above.

[0084] The water-soluble solid material may be any substance as long as it is water-soluble and solid at 25°C and 1 standard atmosphere. For example, it is preferably one or more selected from a humectant, a surfactant, and a solubilizer. In this case, redissolubility / redispersibility and intermittent printing stability tend to be better.

[0085] 1.1.2.1 Moisturizer

[0086] The ink composition A preferably contains a moisturizing agent. The moisturizing agent has a function of suppressing the volatilization of water and tends to improve the intermittent printing stability when used as an inkjet ink composition.

[0087] Examples of moisturizing agents include ureas, such as urea, ethylene urea, tetramethyl urea, and thiourea, and betaines (such as trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine, N,N,N-trimethylalanine, N,N,N-triethylalanine, N,N,N-triisopropylalanine, N,N,N-trimethylalanine, carnitine, and acetylcarnitine).

[0088] The content of the moisturizing agent is preferably 10 to 70% by mass, more preferably 30 to 60% by mass, further preferably 40 to 60% by mass, and particularly preferably 50 to 60% by mass, relative to the total amount of the ink composition A.

[0089] 1.1.2.2 Surfactants

[0090] The ink composition A preferably contains a surfactant. The inclusion of a surfactant tends to improve intermittent printing stability when the ink composition is prepared as an inkjet ink composition, for example.

[0091] Among the surfactants, for example, acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants can be preferably used.

[0092] The acetylene glycol surfactant is not particularly limited, and examples thereof include Surfynol 104E, 104H, 104A, 104PA, 104S, and DF110D (all trade names, manufactured by Air Products and Chemicals), Olefin E1004, E1010, E1020, PD-001, PD-002W, PD-003, PD-004, EXP.4001, EXP.4036, and EXP.4051 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), and Acetylenol E00 and E200 (all trade names, manufactured by Kawakane Fine Chemicals Co., Ltd.).

[0093] The silicone surfactant is not particularly limited, but preferably a polysiloxane compound is used. The polysiloxane compound is not particularly limited, but examples thereof include polyether-modified organosiloxanes. Commercially available examples of such polyether-modified organosiloxanes include KF-6004 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0094] As the fluorine-based surfactant, a fluorine-modified polymer is preferably used. Specific examples thereof include SURFLON S-242 (trade name, manufactured by AGC Seimi Chemical Co., Ltd., Japan) and FTERGENT 245F (manufactured by NEOS Co., Ltd., Japan).

[0095] The content of the surfactant is preferably 0.1 to 10% by mass, more preferably 0.5 to 8% by mass, further preferably 0.5 to 5% by mass, and particularly preferably 1 to 3% by mass, relative to the total amount of the ink composition A.

[0096] 1.1.2.3 Solubilizer

[0097] The ink composition A preferably contains a solubilizer. A "solubilizer" refers to a component that promotes the dissolution of one or more components of the ink composition A in water. The inclusion of a solubilizer tends to improve intermittent printing stability when prepared as an inkjet ink composition.

[0098] The solubilizing agent is not particularly limited, but is preferably an amide. Among amides, cyclic amides are preferred, and lactams such as ε-caprolactam are particularly preferred.

[0099] The content of the solubilizer is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, further preferably 15 to 30% by mass, and particularly preferably 15 to 25% by mass, relative to the total amount of the ink composition A.

[0100] Among these, the substance that is water-soluble and solid at 25°C and 1 standard atmosphere is preferably one or more selected from trimethylglycine, urea, and ε-caprolactam, and more preferably contains trimethylglycine, urea, and ε-caprolactam. In this case, intermittent printing stability tends to be improved when ink composition A is formulated as an inkjet ink composition.

[0101] The content of the water-soluble solid matter is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, further preferably 15 to 30% by mass, and particularly preferably 15 to 25% by mass, relative to the total amount of the ink composition A.

[0102] 1.1.3 Liquid substances

[0103] In ink composition A, the content of a substance that is liquid at 25°C and 1 standard atmosphere (hereinafter also referred to as "liquid substance") is 20% by mass or less relative to the total amount of ink composition A. When the content of the liquid substance is 20% by mass or less relative to the total amount of ink composition A, the storage properties of the ink composition A are improved. Furthermore, the hydrolysis reaction of the colorant can be reduced, thereby achieving excellent color development. The content of the liquid substance relative to the total amount of ink composition A is 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 3% by mass or less, even more particularly preferably 1% by mass or less, even more particularly preferably 0.5% by mass or less, and most particularly preferably contains no liquid substance (0% by mass).

[0104] Examples of the liquid substance include water and organic solvents, which will be described in detail later.

[0105] 1.1.4 Water-insoluble solid matter

[0106] The content of water-insoluble substances other than the colorant in ink composition A that are solid at 25°C and 1 standard atmosphere (hereinafter referred to as "water-insoluble solids") is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, particularly preferably 0.1% by mass or less, and even more preferably no water-insoluble solids (0% by mass). When the water-insoluble solids content is within this range, intermittent printing stability tends to be improved.

[0107] In addition, "water-insoluble" means not being "water-soluble" as described above. "Water-insoluble" means, for example, that the solubility in water at 20°C is 0 g / 100 g of water.

[0108] The water-insoluble solid material is not particularly limited, and examples thereof include resins and inorganic fine particles.

[0109] Examples of the resin include polyurethane resins, acrylic resins, fluorene resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, ethylene-vinyl acetate resins, vinyl acetate resins, butadiene resins, styrene resins, cross-linked acrylic resins, cross-linked styrene resins, benzoguanamine resins, phenolic resins, silicone resins, epoxy resins, paraffin resins, and fluororesins. Examples of the resin include wax and powder, preferably powder.

[0110] Polyurethane resins are a general term for resins containing urethane bonds. In addition to urethane bonds, polyether-type polyurethane resins containing ether bonds in the main chain, polyester-type polyurethane resins containing ester bonds in the main chain, and polycarbonate-type polyurethane resins containing carbonate bonds in the main chain can also be used as polyurethane resins.

[0111] Acrylic resins are a general term for polymers obtained by polymerizing at least one acrylic monomer, such as (meth)acrylic acid or (meth)acrylic ester, as a component. Examples include resins obtained from acrylic monomers and copolymers of acrylic monomers with other monomers. Examples include acrylic-vinyl resins, which are copolymers of acrylic monomers with vinyl monomers. Other examples include copolymers with vinyl monomers such as styrene. Acrylic monomers such as acrylamide and acrylonitrile can also be used.

[0112] Styrene acrylic resins are copolymers obtained from styrene monomers and acrylic monomers, and examples thereof include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylate copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylate copolymers.

[0113] The vinyl chloride resin may be a vinyl chloride-vinyl acetate copolymer.

[0114] The polyolefin-based resin has an olefin such as ethylene, propylene, or butene in its structural skeleton, and any known polyolefin-based resin can be appropriately selected and used.

[0115] Inorganic particles can be used as long as they are transparent when included in the inkjet ink composition (for example, at a content of 3% by mass relative to the total composition). "Transparent" refers to a property of light-transmitting substances in which the transmittance is extremely high, allowing the opposite side to be seen through the substance. Examples of inorganic particles (excluding the aforementioned colorants) include calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass, talc, mica, magnesium oxide, and zinc oxide.

[0116] 1.1.5 Other ingredients

[0117] In addition to the above-mentioned components, ink composition A may also contain various additives, such as a pH adjuster, wax, chelating agent, rust inhibitor, mildew inhibitor, antioxidant, anti-reducing agent, and evaporation accelerator, as needed. Furthermore, these other components may be water-soluble and solid at 25°C and 1 atmosphere, or liquid at 25°C and 1 atmosphere.

[0118] The pH adjuster is not particularly limited, and examples thereof include an appropriate combination of an acid, a base, a weak acid, and a weak base. Examples of acids and bases used in such a combination include sulfuric acid, hydrochloric acid, nitric acid, and the like as inorganic acids; lithium hydroxide, sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate, disodium hydrogen phosphate, potassium carbonate, sodium carbonate, sodium bicarbonate, ammonia, and the like as inorganic bases; triethanolamine, diethanolamine, monoethanolamine, tripropanolamine, triisopropanolamine, diisopropanolamine, trishydroxymethylaminomethane (THAM), and the like as organic acids; adipic acid, citric acid, succinic acid, lactic acid, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid ( BES), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), morpholinoethanesulfonic acid (MES), carbamoylmethyliminodiacetic acid (ADA), piperazine-1,4-bis(2-ethanesulfonic acid) (PIPES), N-(2-acetamido)-2-aminoethanesulfonic acid (ACES), co-amine hydrochloric acid, N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), acetamidoglycine, tris(hydroxymethyl)methylglycine, glycine amide, catenin, Good's buffer, phosphate buffer, citrate buffer, Tris buffer, etc.

[0119] When other components are contained, the content thereof is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, further preferably 0.1 to 1% by mass, and particularly preferably 0.3 to 1% by mass, relative to the total amount of the ink composition A.

[0120] 1.1.6 Preparation method

[0121] The method for preparing ink composition A is not particularly limited and may include a method of mixing the above-mentioned components in any order, a method of mixing the above-mentioned components with a liquid medium such as water, and then removing the liquid medium. A preferred method for preparing ink composition A is freeze-drying or spray-drying the mixture obtained by mixing the above-mentioned components with a liquid medium such as water.

[0122] Freeze-drying and spray-drying increase the surface area of ​​the dried material compared to natural drying, resulting in improved redissolubility and redispersibility. Furthermore, freeze-drying does not require heat application, and even with spray drying, the heating time is extremely short, thus minimizing thermal damage to the ink composition A.

[0123] Freeze drying can be performed using a known freeze drying apparatus. For example, "FD-1000" manufactured by Tokyo Rikaki Co., Ltd. can be used as a freeze drying apparatus.

[0124] Freeze-drying preferably includes a pre-freezing step and a freeze-drying step.

[0125] The pre-freezing step involves cooling the sample with a low-temperature liquid. The temperature of the pre-freezing step is not particularly limited, but is preferably between -70°C and -200°C. Examples of the low-temperature liquid used in the pre-freezing step include liquid nitrogen, liquid ethanol, and liquid acetone.

[0126] The freeze-drying process involves decompressing the sample and allowing it to stand for a predetermined period of time, thereby vaporizing the liquid medium in the sample and freeze-drying it. The freeze-drying temperature is not particularly limited, but is preferably set below the collapse temperature of the freeze-dried sample, preferably above -80°C. The pressure during decompression is not particularly limited, but is preferably below 100 mmHg, and most preferably below 20 mmHg. The freeze-drying time is also not particularly limited, but is preferably 2 to 24 hours, and most preferably approximately 10 hours.

[0127] Spray drying can be performed using a known spray drying apparatus. For example, "ADL311S-A" manufactured by Yamada Scientific Co., Ltd. can be used as a spray drying apparatus.

[0128] The drying temperature of the spray drying is preferably 150 to 220°C at the inlet and 30 to 60°C at the outlet, more preferably 180 to 220°C at the inlet and 50 to 60°C at the outlet.

[0129] 1.1.7 Saving method

[0130] The ink composition A is preferably stored in a container having a water vapor permeability of 5 g / m2 under a temperature of 20°C and a humidity of 90% RH as measured in accordance with JIS K7129.2 In this case, the storage properties tend to be improved and the deactivation of the color material tends to be reduced.

[0131] The water vapor permeability measured in accordance with JIS K7129 at a temperature of 20°C and a humidity of 90% RH is preferably 3 g / m 2 / day or less, more preferably 2g / m 2 / day or less.

[0132] The water vapor permeability measured in accordance with JIS K7129 at a temperature of 20°C and a humidity of 90% RH is 5 g / m 2 The material having a density of less than 1 / day is preferably a laminated body obtained by laminating a resin layer such as polyethylene terephthalate or polypropylene and a barrier layer such as aluminum foil or aluminum vapor-deposited film.

[0133] The container preferably includes at least one of a mechanism for mixing and stirring the ink composition A and the aqueous solution B, and a mechanism for heating the mixed ink composition A and aqueous solution B. This allows for efficient mixing, described below, and tends to improve resolubility and re-dispersibility.

[0134] At least one embodiment of a mixing and stirring mechanism is described. The mixing and stirring mechanism is located below the container, preferably on the bottom surface of the container. Preferably, the mixing and stirring mechanism includes a rotating blade, a rotating shaft, and a motor. The rotating blade is supported by the rotating shaft, which is rotated by the motor, and the rotating blade is rotated by the motor.

[0135] At least one embodiment of a heating mechanism will be described. The heating mechanism may be a heater that directly heats the ink composition A and the aqueous solution B by contacting the heater, or a heater that indirectly heats the ink composition A and the aqueous solution B by heating a container attached to the outside of the container. The temperature of the heater is not particularly limited, but is preferably 30 to 80°C, more preferably 30 to 60°C.

[0136] The capacity of the container is preferably 20 L or less, more preferably 10 L or less. When the capacity of the container is within the above range, the mixing step described below can be performed efficiently, and the re-dissolution and re-dispersibility tend to be improved.

[0137] 1.2 Preparation of aqueous solution B

[0138] The method for using the ink according to one embodiment of the present invention includes an aqueous solution B preparation step of preparing an aqueous solution B. Hereinafter, various components contained in the aqueous solution B will be described.

[0139] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B. This can improve intermittent printing stability.

[0140] 1.2.1 Water

[0141] Aqueous solution B contains water. The water is not particularly limited; examples include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as water that has been free of ionic impurities as much as possible, such as ultrapure water. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can prevent the growth of mold and bacteria during long-term storage of aqueous solution B.

[0142] The water content is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, particularly preferably 90% by mass or more, even more particularly preferably 95% by mass or more, and even more particularly preferably 100% by mass, relative to the total amount of the aqueous solution B. In particular, when the aqueous solution B contains 60% by mass or more of water relative to the total amount of the aqueous solution B, intermittent printing stability tends to be further improved.

[0143] 1.2.2 Organic solvents

[0144] The aqueous solution B may contain an organic solvent. Examples of the organic solvent include esters, alkylene glycol ethers, cyclic esters, amides, alcohols, and polyols.

[0145] Examples of the esters include glycol monoacetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate; and glycol diesters such as ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, and dipropylene glycol acetate propionate.

[0146] As the alkylene glycol ethers, any alkylene glycol monoether or diether may be used, and alkyl ethers are preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether. and alkylene glycol monoalkyl ethers; and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0147] Examples of the cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-caprolactone, γ-caprolactone, δ-caprolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonanolactone, ε-nonanolactone, and ε-decanolactone, and compounds thereof in which the hydrogen atoms of the methylene groups adjacent to the carbonyl group are substituted with alkyl groups having 1 to 4 carbon atoms.

[0148] Examples of the amides include cyclic amides and non-cyclic amides, and examples of the non-cyclic amides include alkoxyalkylamides.

[0149] Examples of cyclic amides include lactams, and examples of lactams include pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, and 1-(2-hydroxyethyl)pyrrolidone.

[0150] Examples of the alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-but ... -n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-isopropoxy-N,N-dimethylpropionamide, 3-isopropoxy-N,N-diethylpropionamide, 3-isopropoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N-methylethylpropionamide, N,N-dimethylisobutyramide, etc.

[0151] Examples of alcohols include compounds in which one hydrogen atom of an alkane is replaced by a hydroxyl group. The alkane is preferably one having 10 or fewer carbon atoms, more preferably one having 6 or fewer carbon atoms, and even more preferably one having 3 or fewer carbon atoms. The alkane has 1 or more carbon atoms, preferably 2 or more carbon atoms. The alkane may be straight-chain or branched. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, tert-butanol, isobutanol, n-pentanol, 2-pentanol, 3-pentanol, tert-pentanol, 2-phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0152] Polyols have two or more hydroxyl groups in their molecules and can be divided into, for example, alkanediols and polyols.

[0153] Examples of alkanediols include compounds in which an alkane is substituted with two hydroxyl groups. Examples of alkanediols include 1,2-alkanediol, which is a general term for compounds in which hydroxyl groups are substituted at the 1- and 2-positions of an alkane, and other alkanediols other than 1,2-alkanediol.

[0154] Examples of 1,2-alkanediols include ethylene glycol, 1,2-propylene glycol (propylene glycol), 1,2-butanediol (1,2BD), 1,2-pentanediol (1,2PD), 1,2-hexanediol (1,2HD), 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 3-methyl-1,2-butanediol, 3-methyl-1,2-pentanediol, 4-methyl-1,2-pentanediol, 3,4-dimethyl-1,2- Pentanediol, 3-ethyl-1,2-pentanediol, 4-ethyl-1,2-pentanediol, 3-methyl-1,2-hexanediol, 4-methyl-1,2-hexanediol, 5-methyl-1,2-hexanediol, 3,4-dimethyl-1,2-hexanediol, 3,5-dimethyl-1,2-hexanediol, 4,5-dimethyl-1,2-hexanediol, 3-ethyl-1,2-hexanediol, 4-ethyl-1,2-hexanediol, 3-ethyl-4-methyl-1,2-hexanediol, etc.

[0155] Examples of other alkanediols include 1,3-propylene glycol, 1,3-butanediol (also known as 1,3-butanediol), 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2,4-pentanediol, 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, and 2-methyl-2-propyl-1,3-propanediol.

[0156] Examples of the polyols include condensates obtained by intermolecular condensation of two or more alkanediol molecules with hydroxyl groups, and compounds having three or more hydroxyl groups.

[0157] Examples of condensates formed by intermolecular condensation of two or more alkanediol molecules via hydroxyl groups include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0158] Compounds having three or more hydroxyl groups are compounds having an alkane or polyether structure as a backbone and having three or more hydroxyl groups. Examples of compounds having three or more hydroxyl groups include glycerol, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylene triol.

[0159] The organic solvent may be used alone or in combination of two or more.

[0160] Among organic solvents, aqueous solution B preferably contains a water-soluble organic solvent. When a water-soluble organic solvent is contained, wettability with respect to ink composition A is improved, and redissolubility and redispersibility tend to be better. The "water solubility" of the water-soluble organic solvent is the same as the "water solubility" of the color material described above.

[0161] The water-soluble organic solvent preferably contains one or more selected from glycerol, 1-(2-hydroxyethyl)pyrrolidin-2-one, triethylene glycol, and triethylene glycol monobutyl ether. When such a water-soluble organic solvent is contained, the redissolubility and redispersibility tend to be better.

[0162] The content of the organic solvent is preferably 50% by mass or less, more preferably less than 50% by mass, further preferably 10 to 45% by mass, particularly preferably 20 to 45% by mass, and even more preferably 30 to 45% by mass, relative to the total amount of the aqueous solution B.

[0163] Aqueous solution B preferably contains an organic solvent with a normal boiling point exceeding 280°C at a concentration of 5% by mass or greater, more preferably 10% by mass or greater, even more preferably 15% by mass or greater, and particularly preferably 20% by mass or greater, relative to the total amount of aqueous solution B. This tends to improve redissolubility and redispersibility. Examples of organic solvents with a normal boiling point exceeding 280°C include triethylene glycol and glycerol.

[0164] 1.2.3 Surfactants

[0165] Aqueous solution B may also contain a surfactant. Surfactants that are liquid at 25°C and 1 standard atmosphere pressure, in addition to the surfactants listed above, may also be included. Examples of surfactants that are liquid at 25°C and 1 standard atmosphere pressure include Olefin PD-002W (acetylenic glycol-based surfactant, trade name, manufactured by Nissin Chemical Industry Co., Ltd.), BYK-348 (silicone-based surfactant, trade name, manufactured by BYK), and SURFLON S-241 (fluorine-based surfactant, trade name, manufactured by AGC Fine Chemicals Co., Ltd.).

[0166] The content of the surfactant is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, further preferably 0.3 to 2% by mass, and particularly preferably 0.3 to 1% by mass, relative to the total amount of the aqueous solution B.

[0167] 1.2.4 Other ingredients

[0168] In addition to the above-mentioned components, the aqueous solution B may contain various additives such as resins, waxes, chelating agents, rust inhibitors, mildew inhibitors, antioxidants, and reducing agents as needed.

[0169] 1.2.5 Preparation method

[0170] The method for preparing aqueous solution B is not particularly limited and can be prepared by mixing the above-mentioned components in any order and, if necessary, filtering to remove impurities. A suitable method for mixing the components is to sequentially add the materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and then stir and mix them. As a filtration method, centrifugal filtration, filter filtration, etc. can be performed as needed.

[0171] 1.3 Mixing process

[0172] The method for using the ink according to one embodiment of the present invention includes a mixing step of mixing the ink composition A and the aqueous solution B when used in an inkjet printer. This minimizes the environmental load during transportation and the storage space required.

[0173] The mixing step is a process that is performed incidentally when using the inkjet printer, and can be performed immediately before using the inkjet printer or during the use of the inkjet printer.

[0174] Immediately before using the inkjet printer means, for example, one week before, three days before, one day before, 12 hours before, six hours before, three hours before, one hour before, 30 minutes before, 15 minutes before, or five minutes before using the inkjet printer.

[0175] The mixing step can be performed inside the inkjet printer or in a container separate from the inkjet printer. The mixing step can also be performed at a location within 100 m, 50 m, 25 m, 10 m, 5 m, or 1 m from the inkjet printer.

[0176] The method for mixing the ink composition A and the aqueous solution B is not particularly limited. For example, a method of adding the ink composition A and the aqueous solution B to a container equipped with a stirring device and stirring and mixing them may be used.

[0177] The mixing ratio of ink composition A and aqueous solution B can be appropriately adjusted depending on the intended purpose. For example, the mass ratio of ink composition A to aqueous solution B (ink composition A / aqueous solution B) is preferably 0.25 to 1.5, more preferably 0.25 to 1.2, further preferably 0.25 to 1.0, and particularly preferably 0.3 to 0.9.

[0178] The inkjet ink composition C obtained through the mixing step has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less, thereby improving redissolubility / redispersibility and intermittent printing stability.

[0179] The surface tension of the inkjet ink composition C is 40 mN / m or less, preferably 38 mN / m or less, more preferably 36 mN / m or less, and particularly preferably 35 mN / m or less. The lower limit of the surface tension is not particularly limited, but is preferably 25 mN / m or more, and more preferably 30 mN / m or more.

[0180] The viscosity of the inkjet ink composition C is 100 mPa·s or less, preferably 50 mPa·s or less, more preferably 30 mPa·s or less, further preferably 15 mPa·s or less, particularly preferably 10 mPa·s or less, and even more preferably 5 mPa·s or less.

[0181] 1.4 Inkjet Printer

[0182] The method of using the ink according to one embodiment of the present invention is for ejecting the above-mentioned inkjet ink composition C from an inkjet printer. Hereinafter, the inkjet printer will be described with reference to the drawings.

[0183] An inkjet printer preferably includes an inkjet head comprising: a nozzle for ejecting an inkjet ink composition; a pressure chamber for supplying the inkjet ink composition; and a circulation path for circulating the inkjet ink composition within the pressure chamber. This tends to improve intermittent printing stability.

[0184] Inkjet head 10 Figure 1 The nozzle is shown as follows: a pressure chamber 2 to which an inkjet ink composition is supplied; and a circulation path 3 to circulate the inkjet ink composition in the pressure chamber 2. Figure 1 In the example shown in FIG. 1 , the nozzle 1 and the pressure chamber 2 are communicated with each other through the communication path 4 .

[0185] The nozzle 1 is a through-hole through which the inkjet ink composition is ejected. More specifically, the nozzle 1 is a through-hole formed in the nozzle plate. The nozzle plate is formed with multiple nozzles, each of which has a pressure chamber 2. A pressure chamber 2 is formed separately for each nozzle 1. The inkjet ink composition is supplied to the pressure chamber 2. When the pressure within the pressure chamber 2 is varied by a pressure generating unit (not shown), a portion of the inkjet ink composition flowing within the communication path 4 is ejected from the nozzle 1 to the outside, while the remaining portion flows into the circulation flow path 3. The path of the circulation flow path 3 is not particularly limited; the flow path can be configured so that the inkjet ink composition flowing into the circulation flow path 3 is supplied to the pressure chamber 2. Furthermore, the inkjet ink composition flowing into the circulation flow path 3 does not necessarily need to be resupplied to the same pressure chamber; it can also be supplied to the pressure chamber corresponding to another nozzle. Furthermore, the entire circulation flow path 3 does not need to be located within the inkjet head 10; as long as the inkjet ink composition flowing out of the pressure chamber 2 is resupplied to the pressure chamber 2, a portion of the flow path can be located outside the inkjet head 10.

[0186] As described above, the inkjet head 10 of this embodiment can effectively circulate the inkjet ink composition in the pressure chamber 2, more specifically, the inkjet ink composition near the nozzle 1, within the head. This tends to further improve intermittent printing stability.

[0187] Examples of the inkjet head 10 include a line head that performs recording in a line method and a tandem head that performs recording in a serial method.

[0188] In a line-type method using a line head, for example, an inkjet head with a width greater than the recording width of the recording medium is fixed to the inkjet printer. The recording medium is then moved in the secondary scanning direction (the longitudinal direction of the recording medium, or the transport direction), and ink droplets are ejected from the nozzles of the inkjet head in conjunction with this movement, thereby recording an image on the recording medium.

[0189] In the serial method using a tandem head, for example, an inkjet head is mounted on a carriage that moves across the width of the recording medium. The carriage then moves in the main scanning direction (the transverse direction, widthwise direction, of the recording medium), and ink droplets are ejected from the nozzle openings of the inkjet head in conjunction with this movement, thereby recording an image on the recording medium.

[0190] The recording medium is not particularly limited, and examples thereof include liquid-absorbing recording media such as paper, film, and cloth, low-liquid-absorbing recording media such as printing paper, and liquid-non-absorbing recording media such as metal, glass, and polymers. Furthermore, the form of the recording medium is also not particularly limited. Examples thereof include films, plates, and cloth.

[0191] The inkjet head 10 may also have a heating unit capable of heating the inkjet ink composition. More specifically, it may also have a heating unit that heats the inkjet ink composition in the circulation flow path composed of the pressure chamber 2, the circulation flow path 3, and the connecting path 4. The heating unit is not particularly limited and can be provided in, for example, the pressure chamber 2, the circulation flow path 3, or the connecting path 4. In addition, a heating unit for heating the nozzle plate may be provided. In the case where the circulation flow path 3 passes through the outside of the inkjet head 10, a heating unit may also be provided in the circulation flow path 3 located outside the inkjet head 10. In addition, a heating unit may also be provided in the ink flow path upstream of the pressure chamber. Here, the ink flow path refers to a flow path for circulating ink. As an ink flow path, for example, it also includes an ink supply path for supplying ink from an ink storage container that stores ink to the inkjet head.

[0192] The lower limit of the heating temperature of the composition is preferably 35°C or higher, more preferably 40°C or higher, and further preferably 45°C or higher. The upper limit is preferably 70°C or lower, more preferably 60°C or lower, and further preferably 50°C or lower.

[0193] The inkjet printer preferably includes at least one of a mechanism for mixing and stirring the ink composition A and the aqueous solution B, and a mechanism for heating the mixed ink composition A and aqueous solution B. This allows for efficient mixing and tends to improve redissolubility and redispersibility.

[0194] At least one embodiment of a mixing and stirring mechanism will be described. The mixing and stirring mechanism is preferably located below the ink container of the inkjet printer, preferably on the bottom surface of the ink container. The mixing and stirring mechanism preferably includes a rotating blade, a rotating shaft, and a motor. The rotating blade is supported by the rotating shaft, which is rotated by the motor, and the rotating blade is rotated by the motor.

[0195] At least one embodiment of a heating mechanism will be described. The heating mechanism may be a heater that directly heats the ink composition A and the aqueous solution B by contacting the ink composition A and the aqueous solution B, or a heater that indirectly heats the ink composition A and the aqueous solution B by heating the ink container attached to the outside of the ink container. The temperature of the heater is not particularly limited, but is preferably 30 to 80°C, more preferably 30 to 60°C.

[0196] As an example of an inkjet printer, Figure 2 Figure 2 shows a perspective view of a serial printer. Figure 2 As shown, the serial printer 20 includes a transport unit 220 and a recording unit 230. The transport unit 220 transports the recording medium F fed into the serial printer toward the recording unit 230 and discharges the recorded recording medium outside the serial printer. Specifically, the transport unit 220 includes various paper feed rollers that transport the conveyed recording medium F in the secondary scanning direction T1.

[0197] The recording unit 230 includes an inkjet head 231 for ejecting a composition onto the recording medium F conveyed from the conveying unit 220 , a carriage 234 on which the inkjet head 231 is mounted, and a carriage moving mechanism 235 for moving the carriage 234 along the main scanning directions S1 and S2 of the recording medium F.

[0198] In a serial printer, the inkjet head 231 is comprised of a head portion whose length is shorter than the width of the recording medium. This head portion moves and records in multiple passes (multi-passes). Furthermore, in a serial printer, the head portion 231 is mounted on a carriage 234 that moves in a predetermined direction. The head portion moves with the movement of the carriage, thereby ejecting the composition onto the recording medium. Thus, recording is performed in two or more passes (multi-passes). A pass is also referred to as a main scan. A secondary scan is performed between passes, during which the recording medium is transported. In other words, the main scan and secondary scan are performed alternately.

[0199] In addition, the inkjet printer is not limited to the above-mentioned serial printer, and may also be the above-mentioned line printer.

[0200] 2. Ink set

[0201] An ink set according to one embodiment of the present invention includes: an ink composition A containing a colorant, a water-soluble substance that is solid at 25°C and 1 standard atmosphere, and a liquid substance at 25°C and 1 standard atmosphere, wherein the content of the substance that is liquid at 25°C and 1 standard atmosphere is 20% by mass or less relative to the total amount of ink composition A; and an aqueous solution B containing water at a concentration of 50% by mass or more relative to the total amount of aqueous solution B. The ink set is prepared by mixing the ink composition A and the aqueous solution B so that the surface tension is 40 mN / m or less and the viscosity is 100 mPa·s or less.

[0202] According to the ink set of this embodiment, the dry ink composition and aqueous solution are mixed to form the inkjet ink before use in an inkjet printer, minimizing the environmental impact of transportation and storage space. Furthermore, the dry ink composition contains a colorant and a water-soluble solid substance, resulting in excellent redissolubility and redispersibility, while the aqueous solution contains at least 50% by mass of water relative to the total amount of the aqueous solution, ensuring excellent intermittent printing stability. Furthermore, by setting the surface tension and viscosity of the mixed inkjet ink composition to predetermined values, stable inkjet ejection is achieved.

[0203] In the present invention, an "ink set" refers to an ink set consisting of at least an ink composition A and an aqueous solution B. An ink set is a set of inks that are mixed and used together. An ink set may contain one ink composition or two or more. The same applies to the aqueous solution contained in the ink set.

[0204] The ink composition A and the aqueous solution B included in the ink set according to this embodiment are as described above, and therefore their description is omitted.

[0205] 3. Method for producing inkjet ink composition

[0206] A method for producing an inkjet ink composition according to one embodiment of the present invention is a method for producing an inkjet ink composition, comprising: mixing an ink composition A and an aqueous solution B when used in a printer; the ink composition A containing a colorant, a water-soluble substance that is solid at 25°C and 1 standard atmosphere, and a content of a liquid substance at 25°C and 1 standard atmosphere, relative to the total amount of the ink composition A; the aqueous solution B containing 50% by mass or more of water relative to the total amount of the aqueous solution B; and the inkjet ink composition having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0207] According to the method for producing an inkjet ink composition according to this embodiment, the dry ink composition and an aqueous solution are mixed to form the inkjet ink before use in an inkjet printer. This minimizes the environmental impact of transportation and storage space. Furthermore, the dry ink composition contains a colorant and a water-soluble solid substance, which improves redissolubility and redispersibility. The aqueous solution contains 50% or more of water relative to the total amount of the aqueous solution, which improves intermittent printing stability. Furthermore, by setting the surface tension and viscosity of the mixed inkjet ink composition to predetermined values, stable inkjet discharge can be achieved.

[0208] The ink composition A and the aqueous solution B used in the production method according to this embodiment are as described above, and the mixing step is the same as the above-mentioned mixing step, so the description thereof is omitted.

[0209] 4. Inkjet ink composition

[0210] An inkjet ink composition according to one embodiment of the present invention is an inkjet ink composition comprising an ink composition A and an aqueous solution B, wherein the ink composition A contains a color material, and a water-soluble substance that is solid at 25°C and 1 standard atmosphere, and the content of the substance that is liquid at 25°C and 1 standard atmosphere is 20% by mass or less relative to the total amount of the ink composition A, and the aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B. The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0211] According to the inkjet ink composition of this embodiment, the dry ink composition and the aqueous solution are mixed to form the inkjet ink before use in an inkjet printer, thereby minimizing the environmental impact of transportation and storage space. Furthermore, the dry ink composition contains a colorant and a water-soluble solid substance, thereby improving redissolubility and redispersibility. The aqueous solution contains 50% or more of water relative to the total amount of the aqueous solution, thereby ensuring excellent intermittent printing stability. Furthermore, by setting the surface tension and viscosity of the mixed inkjet ink composition to predetermined values, stable inkjet discharge can be achieved.

[0212] The ink composition A and the aqueous solution B constituting the inkjet ink composition according to this embodiment are as described above, and therefore their description is omitted.

[0213] The ratio of ink composition A to aqueous solution B can be appropriately adjusted depending on the intended purpose. For example, the mass ratio of ink composition A to aqueous solution B (ink composition A / aqueous solution B) is preferably 0.25 to 1.5, more preferably 0.25 to 1.2, further preferably 0.25 to 1.0, and particularly preferably 0.3 to 0.9.

[0214] 5. Examples

[0215] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. "%" below refers to mass basis unless otherwise specified.

[0216] 5.1 Preparation of ink composition

[0217] The components were placed in a container to form the composition shown in Table 1, mixed and stirred for 2 hours using a magnetic stirrer, and then dispersed using a bead mill filled with zirconia beads having a diameter of 0.3 mm. After thorough mixing and stirring for 1 hour, the mixture was filtered using a 5 μm PTFE membrane filter to obtain each pre-drying ink.

[0218] The colorant used in preparing Ink 3 before drying is pre-mixed with a water-soluble styrene-acrylic resin, or pigment dispersant (not shown in the table), in water at a mass ratio of 2:1 (pigment: pigment dispersant). This pigment dispersion is then stirred thoroughly to prepare the ink. The colorant column indicates the mass percentage of the pigment, calculated from the solids concentration of the pigment dispersion.

[0219] The obtained pre-drying inks were dried using the ink drying methods described in Tables 4 and 5 to obtain the post-drying inks described in Table 2.

[0220] Specifically, using the device model "FD-1000" (manufactured by Tokyo Rikaki Co., Ltd.), 30 g of the pre-drying ink was placed in a 50 ml screw tube and freeze-dried at a cold trap temperature of -45°C for 10 hours (additional time was added if drying was not completed) to obtain each post-drying ink.

[0221] Furthermore, using an organic solvent recovery device "GAS410" (manufactured by Yamada Scientific Co., Ltd.) with a device model "ADL311S-A" (manufactured by Yamada Scientific Co., Ltd.), spray drying was performed under conditions of an inlet temperature of 200°C and an outlet temperature of 60°C to obtain the dried ink 1 involved in Example 3.

[0222] Then, the ink was left to stand in an open state for 30 days under an environment of 25° C. and 40% RH to allow natural drying, thereby obtaining dried ink 1 according to Example 18.

[0223] Tables 1 and 2 are described below.

[0224] Surfynol 104E (produced by Air Products and Chemicals, trade name, acetylene glycol surfactant)

[0225] Styrene-acrylic resin (Nippon Paint Industrial Coatings group AS resin, trade name "FS-102")

[0226] 5.2 Preparation of aqueous solution

[0227] Each component was placed in a container so as to have the composition shown in Table 3 and mixed thoroughly to obtain each aqueous solution.

[0228] Table 3 is described below.

[0229] Olefin PD002W (produced by Nissin Chemical Industry Co., Ltd., trade name, acetylene glycol surfactant)

[0230] 5.3 Preparation of inkjet ink composition

[0231] The dried ink obtained above and the aqueous solution were mixed according to the combinations and mixing ratios shown in Tables 4 and 5 to obtain the inkjet ink compositions of each example. Specifically, the dried ink and the aqueous solution were placed in the containers shown in Tables 4 and 5. If the container had a heating / stirring mechanism, mixing and stirring were performed at 60°C and a stirring speed of 350 rpm for one hour. If the container did not have a heating / stirring mechanism, mixing and stirring were performed manually using a stirring rod to obtain the inkjet ink compositions of each example.

[0232] In Example 6, the dried ink and aqueous solution were placed directly into an ink tank capable of injecting liquid, heating, and stirring, and into an ink tank of a Seiko Epson Corporation inkjet printer "PX-G930" modified to supply the ink composition from the ink tank to the print head. The mixture was then mixed and stirred at 60°C and a stirring speed of 350 rpm for 1 hour to obtain an inkjet ink composition.

[0233] In Example 19, the dried ink and the aqueous solution were placed in a container, mixed and stirred at 60°C and a stirring speed of 350 rpm for 1 hour, and then the composition in the container was placed in an inkjet printer "PX-G930" manufactured by Seiko Epson Corporation that had been modified as described above, and mixed and stirred at 60°C and a stirring speed of 350 rpm for 1 hour, thereby obtaining an inkjet ink composition.

[0234] The surface tension of the inkjet ink compositions obtained in each example was measured using a surface tensiometer (DY-300, manufactured by Kyowa Interface Science Co., Ltd.) using the vertical film formation method (Wilhelmy method). The viscosity was also measured using a vibration viscometer (VM-100, manufactured by Sekonic Co., Ltd.) in accordance with JIS Z8809. The results are shown in Tables 4 and 5.

[0235] 5.4 Evaluation Method

[0236] 5.4.1 Resolubility / redispersibility

[0237] The peak absorbance of the ink obtained before drying in the visible light region was set as 100% (for color materials without a peak, the value at a wavelength of 500 nm was set as 100%). Similarly, the peak absorbance of the inkjet ink composition obtained above was measured, and the value of (peak value of the inkjet ink composition) / (peak value of the ink before drying) was calculated. The redissolubility / redispersibility was evaluated according to the following criteria.

[0238] (Judgment Criteria)

[0239] A+: above 98%

[0240] A: 95% or more but less than 98%

[0241] B: 90% or more but less than 95%

[0242] C: less than 95%

[0243] 5.4.2 Intermittent printing stability

[0244] The inkjet ink composition obtained above was filled into a Seiko Epson Corporation inkjet printer "PX-G930". After the inkjet head was allowed to run for 2 minutes under an environment of 40°C and 20% RH, the ratio of nozzles that failed to eject normally was determined, and the intermittent printing stability was evaluated according to the following criteria.

[0245] (Judgment Criteria)

[0246] A+: less than 5%

[0247] A: 5% or more but less than 10%

[0248] B: 10% or more but less than 20%

[0249] C: more than 20%

[0250] 5.4.3 Storage

[0251] The dried ink obtained above was placed in the containers shown in Tables 4 and 5 and allowed to stand for 3 hours at 30°C and 90% RH. The rate of increase in water content was calculated from the weight difference before and after standing, and the storage performance was evaluated according to the following criteria.

[0252] (Judgment Criteria)

[0253] A: less than 0.5%

[0254] B: More than 0.5% and less than 1%

[0255] C: More than 1%

[0256] 5.4.4 Inactivation stability

[0257] An inkjet ink composition was prepared in the same manner as in "5.3 Preparation of Inkjet Ink Composition," except that the dried ink obtained above was stored in a container and allowed to stand for 10 days at 60°C and 50% RH. This inkjet ink composition was used to create printed materials (reactive dye: cotton, acid dye: silk, pigment: polyester). The color difference (ΔEcmc2:1) between the printed materials and those created using the dried ink but not allowed to stand for 10 days at 60°C and 50% RH was determined. Deactivation stability was evaluated using the following criteria.

[0258] (Judgment Criteria)

[0259] A: 4 or more

[0260] B: 2 or more but less than 4

[0261] C: less than 2

[0262] 5.4.5 Water solubility

[0263] Regarding the water solubility described in Tables 1 to 3, the solubility in water was evaluated according to the following criteria.

[0264] (Judgment Criteria)

[0265] A: 5wt% or more

[0266] B: greater than 0wt% and less than 5wt%

[0267] C: Insoluble. 0wt%

[0268] 5.5 Evaluation results

[0269] Tables 4 and 5 show the evaluation results. Ink composition A and aqueous solution B were mixed for use in an inkjet printer to obtain an inkjet ink composition C having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less after mixing. The ink composition A contained a colorant, a water-soluble substance that was solid at 25°C and 1 standard atmosphere, and a liquid substance at 25°C and 1 standard atmosphere, with the content of the substance being 20% ​​by mass or less relative to the total amount of ink composition A. The aqueous solution B contained 50% by mass or more of water relative to the total amount of aqueous solution B. In each example of the method for using this ink, the ink exhibited excellent redissolubility / redispersibility, intermittent printing stability, and storage properties.

[0270] In contrast, in the usage methods of the inks according to the comparative examples that did not satisfy the above-mentioned configuration, at least one of the re-dissolubility / re-dispersibility, intermittent printing stability, and storage properties was inferior.

[0271] The following can be derived from the above-mentioned embodiments.

[0272] One way to use ink,

[0273] The ink composition A and the aqueous solution B are mixed when used in an inkjet printer to obtain an inkjet ink composition C having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less after mixing, and the inkjet ink composition C is ejected from the inkjet printer for use.

[0274] The ink composition A comprises a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A.

[0275] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B.

[0276] In one embodiment of the method for using the ink,

[0277] The color material is a water-soluble color material.

[0278] In any of the above-mentioned methods of using the ink, it is also possible to:

[0279] The color material is a dye.

[0280] In any of the above-mentioned methods of using the ink,

[0281] The color material is a reactive dye.

[0282] In any of the above-mentioned methods of using the ink, it is also possible to:

[0283] The water-soluble substance that is solid at 25° C. and one standard atmospheric pressure is at least one selected from a humectant, a surfactant, and a solubilizer.

[0284] In any of the above-mentioned methods of using the ink, it is also possible to:

[0285] The water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure is at least one selected from trimethylglycine, urea, and ε-caprolactam.

[0286] In any of the above-mentioned methods of using the ink, it is also possible to:

[0287] The content of the water-insoluble substance other than the color material in the ink composition A that is solid at 25° C. and 1 standard atmosphere is 1% by mass or less relative to the total amount of the ink composition A.

[0288] In any of the above-mentioned methods of using the ink, it is also possible to:

[0289] The content of the coloring material is 35% by mass or less relative to the total amount of the ink composition A.

[0290] In any of the above-mentioned methods of using the ink, it is also possible to:

[0291] The ink composition A is prepared by freeze drying or spray drying.

[0292] In any of the above-mentioned methods of using the ink, it is also possible to:

[0293] The aqueous solution B contains 60% by mass or more of water relative to the total amount of the aqueous solution B.

[0294] In any of the above-mentioned methods of using the ink, it is also possible to:

[0295] The aqueous solution B further contains a water-soluble organic solvent.

[0296] In any of the above-mentioned methods of using the ink, it is also possible to:

[0297] The inkjet printer includes at least one of a mechanism for mixing and stirring the ink composition A and the aqueous solution B and a mechanism for heating the mixed ink composition A and the aqueous solution B.

[0298] In any of the above-mentioned methods of using the ink, it is also possible to:

[0299] The ink composition A is stored in a container having a water vapor permeability of 5 g / m2 measured in accordance with JIS K7129 under an environment of a temperature of 20° C. and a humidity of 90% RH. 2 / day or less of the material composition.

[0300] In the above-mentioned method of using the ink, it is also possible to:

[0301] The container includes at least one of a mechanism for mixing and stirring the ink composition A and the aqueous solution B and a mechanism for heating the mixed ink composition A and the aqueous solution B.

[0302] In any of the above-mentioned methods of using the ink, it is also possible to:

[0303] The capacity of the container is 20 L or less.

[0304] In any of the above-mentioned methods of using the ink, it is also possible to:

[0305] The inkjet printer includes an inkjet head having a nozzle for discharging the inkjet ink composition C, a pressure chamber to which the inkjet ink composition C is supplied, and a circulation flow path capable of circulating the inkjet ink composition C in the pressure chamber.

[0306] One approach to ink sets includes:

[0307] Ink composition A, comprising a colorant, a water-soluble substance that is solid at 25°C and 1 standard atmosphere, and a liquid substance at 25°C and 1 standard atmosphere, wherein the content of the liquid substance is 20% by mass or less relative to the total amount of ink composition A; and

[0308] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B,

[0309] The ink set is prepared by mixing the ink composition A and the aqueous solution B so that the surface tension is 40 mN / m or less and the viscosity is 100 mPa·s or less.

[0310] One embodiment of a method for producing an inkjet ink composition,

[0311] The method for producing an inkjet ink composition comprises the steps of mixing ink composition A and aqueous solution B when used in an inkjet printer.

[0312] The ink composition A comprises a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A.

[0313] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B,

[0314] The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0315] In one embodiment of the inkjet ink composition, the inkjet ink composition comprises an ink composition A and an aqueous solution B.

[0316] The ink composition A comprises a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A.

[0317] The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B,

[0318] The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0319] The present invention is not limited to the above-mentioned embodiments and can be modified in various ways. For example, the present invention includes constituent elements that are substantially the same as the structures described in the embodiments, such as constituent elements with the same functions, methods and results, or constituent elements with the same purposes and effects. Furthermore, the present invention includes constituent elements that replace the non-essential parts described in the embodiments. Furthermore, the present invention includes constituent elements that can exert the same effects as the structures described in the embodiments or constituent elements that achieve the same purposes. Furthermore, the present invention includes structures in which known technologies are added to the structures described in the embodiments.

Claims

1. A method for using ink, characterized in that: The ink composition A and the aqueous solution B are mixed when used in an inkjet printer to obtain an inkjet ink composition C having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less after mixing, and the inkjet ink composition C is ejected from the inkjet printer for use. The ink composition A contains a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A. The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B.

2. The method according to claim 1, characterized in that The color material is a water-soluble color material.

3. The method according to claim 1, characterized in that The color material is a dye.

4. The method according to claim 3, characterized in that The color material is a reactive dye.

5. The method according to claim 1, wherein The substance that is water-soluble and solid at 25° C. and one standard atmospheric pressure is at least one selected from a humectant, a surfactant, and a solubilizer.

6. The method according to claim 1, wherein The substance that is water-soluble and solid at 25° C. and one standard atmospheric pressure is at least one selected from trimethylglycine, urea, and ε-caprolactam.

7. The method according to claim 1, characterized in that The content of the water-insoluble substance other than the color material in the ink composition A that is solid under an environment of 25° C. and 1 standard atmosphere is 1% by mass or less relative to the total amount of the ink composition A.

8. The method according to claim 1, characterized in that The content of the coloring material is 35% by mass or less relative to the total amount of the ink composition A.

9. The method according to claim 1, characterized in that The ink composition A is prepared by freeze drying or spray drying.

10. The method according to claim 1, characterized in that The aqueous solution B contains 60% by mass or more of water relative to the total amount of the aqueous solution B.

11. The method according to claim 1, wherein The aqueous solution B further contains a water-soluble organic solvent.

12. The method according to claim 1, characterized in that The inkjet printer includes at least one of a mechanism for mixing and stirring the ink composition A and the aqueous solution B, and a mechanism for heating the mixed ink composition A and the aqueous solution B.

13. The method according to claim 1, wherein The ink composition A is stored in a container having a water vapor permeability of 5 g / m2 under a temperature of 20° C. and a humidity of 90% RH as measured in accordance with JIS K7129. 2 / day or less of the material composition.

14. The method according to claim 13, characterized in that The container includes at least one of a mechanism for mixing and stirring the ink composition A and the aqueous solution B, and a mechanism for heating the mixed ink composition A and the aqueous solution B.

15. The method according to claim 13 or 14, characterized in that The capacity of the container is 20 L or less.

16. The method according to claim 1, wherein The inkjet printer includes an inkjet head, wherein the inkjet head includes: a nozzle for ejecting the inkjet ink composition C; a pressure chamber supplied with the inkjet ink composition C; and The circulation flow path can circulate the inkjet ink composition C in the pressure chamber.

17. An ink set, characterized in that: include: Ink composition A comprises a colorant and a water-soluble substance that is solid at 25°C and 1 standard atmosphere, wherein the content of the substance that is liquid at 25°C and 1 standard atmosphere is 20% by mass or less relative to the total amount of ink composition A; as well as The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B, The ink set is prepared by mixing the ink composition A and the aqueous solution B so that the surface tension is 40 mN / m or less and the viscosity is 100 mPa·s or less.

18. A method for producing an inkjet ink composition, characterized in that: The method comprises the steps of mixing the ink composition A and the aqueous solution B when used in an inkjet printer, The ink composition A contains a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A. The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B, The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

19. An inkjet ink composition, characterized in that comprising ink composition A and aqueous solution B, The ink composition A contains a colorant and a water-soluble substance that is solid at 25° C. and 1 standard atmospheric pressure, and the content of the liquid substance at 25° C. and 1 standard atmospheric pressure is 20% by mass or less relative to the total amount of the ink composition A. The aqueous solution B contains 50% by mass or more of water relative to the total amount of the aqueous solution B, The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

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