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

Abstract

To provide a method for using an ink capable of making re-solubility / re-dispersibility, and intermittent printing stability of an inkjet composition obtained by adding a liquid medium to a dried ink composition excellent, while reducing environmental load during transportation and storage space pressure during ink storage, and making storage of the dried ink composition excellent.SOLUTION: A method of using ink according to an embodiment of the present invention involves mixing an ink composition A, which contains a colorant and a substance that is solid under conditions of 25°C and 1 atm and in which the amount of liquid substance at 25°C and 1 atm is 20% by mass or less of the total amount of ink composition A, with an aqueous solution B containing 50% by mass or more water based on the total amount of aqueous solution B, 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, which is then ejected from the inkjet printer for use.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method of using an ink, an ink set, a method of making an inkjet ink composition, and an inkjet ink composition. [Background technology]

[0002] The inkjet recording method is capable of recording high-resolution images using a relatively simple device, and has been rapidly developing in various fields. In particular, the use of an ink composition from which at least a portion of the liquid medium has been removed (dry ink composition) has been investigated.

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

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-045469 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional methods have not been able to reduce the environmental impact during transportation due to the weight of the ink medium or the storage space required for ink storage. Furthermore, it has not been possible to improve the resolubility / redispersibility and intermittent printing stability of an inkjet ink composition obtained by adding a liquid medium to a dry ink composition while improving the storage stability of the dry ink composition. [Means for solving the problem]

[0006] One aspect of the method for using the ink according to the present invention is to an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; an aqueous solution B containing water in an amount of 50 mass% or more relative to the total amount of the aqueous solution B; When used in inkjet printers, After mixing, an ink-jet ink composition C having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less is obtained, and is ejected from the ink-jet printer.

[0007] One aspect of the ink set according to the present invention is an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; and an aqueous solution B containing water in an amount of 50% by mass or more based on the total amount of the aqueous solution B, The ink composition A and the aqueous solution B are mixed together so that the surface tension is 40 mN / m or less and the viscosity is 100 mPa·s or less.

[0008] One embodiment of the method for producing an inkjet ink composition according to the present invention comprises the steps of: 1. A method for making an inkjet ink composition, comprising: an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; and an aqueous solution B containing water in an amount of 50% by mass or more relative to the total amount of the aqueous solution B, when used in an inkjet printer, The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0009] One embodiment of the inkjet ink composition according to the present invention comprises: an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; an aqueous solution B containing water in an amount of 50 mass% or more based on the total amount of the aqueous solution B; An inkjet ink composition comprising: The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic diagram illustrating the configuration of an inkjet head that can be used in the present embodiment. [Figure 2] FIG. 1 is a perspective view showing a serial inkjet device according to an embodiment of the present invention. [Figure 3] Table 1 lists example compositions of inks before drying. [Figure 4] Table 2 lists example compositions of inks after drying. [Figure 5] Table 3 lists example compositions of aqueous solutions. [Figure 6] Table 4 lists the conditions and evaluation results for each example. [Figure 7] Table 5 lists the conditions and evaluation results for each example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described. The embodiments described below are examples of the present invention. The present invention is not limited to the following embodiments, and includes various modified forms that are implemented within the scope of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

[0012] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0013] 1. How to use the ink A method for using an ink according to one embodiment of the present invention involves mixing ink composition A, which contains a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, such that the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less, based on the total amount of ink composition A, with aqueous solution B, which contains water at 50 mass% or more, based on the total amount of aqueous solution B, prior to use in an inkjet printer, to obtain inkjet ink composition C, which has a surface tension of 40 mN / m or less and a viscosity of 100 mPa s or less after mixing, and then ejecting the inkjet ink composition C from the inkjet printer.

[0014] In the conventional method, the ink is not mixed immediately before use in the inkjet printer, and therefore the environmental impact due to transportation and the storage space required cannot be reduced. According to the method of the present invention, the dry ink composition and the aqueous solution are mixed to produce an inkjet ink immediately before use in an inkjet printer, thereby minimizing the environmental impact of transportation and the storage space required. For example, if an aqueous solution containing 50% by mass or more of water is prepared prior to use in the printer, the environmental impact of transportation and the storage space required can be reduced accordingly.

[0015] Furthermore, the dry ink composition can have good resolubility / redispersibility by containing a colorant and a water-soluble solid substance, and the water-soluble solution can have good intermittent printing stability by containing water in an amount of 50 mass% or more based on the total amount of the water-soluble solution. In addition, by adjusting the surface tension and viscosity of the inkjet ink composition after mixing to predetermined values, inkjet ejection can be stabilized.

[0016] Each step of the method according to this embodiment will now be described.

[0017] 1.1 Ink composition A preparation process The method of using the ink according to this embodiment includes the step of preparing an ink composition A. Each component contained in the ink composition A will be described below.

[0018] Ink composition A contains a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, and the content of the substance that is liquid at 25°C and 1 atmospheric pressure is 20 mass% or less of the total amount of ink composition A. This allows for good resolubility / redispersibility and storage stability.

[0019] 1.1.1 Colorants Ink composition A contains a coloring material, such as a dye or a pigment.

[0020] (dye) Dyes include, for example, acid dyes, direct dyes, reactive dyes, basic dyes, and disperse dyes.

[0021] The yellow dye is not particularly limited, but 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, and CI Direct Yellow 1, 8, 11, 12, 24, 26, 27, and 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.

[0022] The magenta dye is not particularly limited, but 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, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240 4, 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, 22 5, 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 Solubilize Red 1, CI Food Red 7, 9, 14.

[0023] 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, 8 7, 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 Solubilized Bat Blue 1, 5, 41, CI Bat Blue 4, 29, 60, CI Food Blue 1, 2, CI Basic Blue 9, 25, 28, 29, 44.

[0024] 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, 168, and Direct Orange. Orange 1, 6, 8, 10, 26, 27, 34, 39, 40, 46, 49, 102, 105, 107, 118; 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.

[0025] 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, 194, 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.

[0026] The above dyes may be used alone or in combination of two or more.

[0027] (pigment) As the pigment, for example, inorganic pigments including carbon black and titanium white, organic pigments, etc. can be used.

[0028] Examples of inorganic pigments that can be used include carbon blacks such as CI Pigment Black 6 (lamp black, vegetable 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), iron oxide, titanium oxide, zinc oxide, and silica.

[0029] 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 of carbon black include Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, and S170, Pretex 35, U, V, and 140U, and Special Black 6, 5, 4A, 4, and 250 manufactured by Degussa. Examples of carbon black include Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, and 700 manufactured by Columbia Carbon Corporation. Examples include Cabot Corporation's Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, and Elftex 12.

[0030] Examples of organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.

[0031] Specific examples of the organic pigment used in ink composition A include the following.

[0032] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc.; CI Vat Blue 4, 60, etc., and 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 exemplified.

[0033] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, and CI Pigment Violet 19, and preferably, one or a mixture of two or more pigments selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19. Solid solutions of the above pigments are also acceptable.

[0034] 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. Of these, preferred examples include 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.

[0035] Examples of orange pigments include CI Pigment Orange 36 or 43, or a mixture thereof. Examples of green pigments include CI Pigment Green 7 or 36, or a mixture thereof.

[0036] Furthermore, a lustrous pigment may be used, and is not particularly limited as long as it can exhibit lustrous properties when attached to a medium. For example, an alloy of one or more metals selected from the group consisting of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper may be used. Examples of the pigment include metal particles (also called metallic pigments) and pearl pigments with pearly luster. Typical examples of the pearl pigment include pigments with pearly luster or interference luster, such as titanium dioxide-coated mica, fish scale foil, and bismuth oxychloride. The luster pigment may be surface-treated to suppress reaction with water.

[0037] White pigments may also be used, including, for example, metal oxides, barium sulfate, calcium carbonate, and other metal compounds. Examples of metal oxides include titanium dioxide, zinc oxide, silica, alumina, magnesium oxide, and the like. The white pigment may also be particles having a hollow structure.

[0038] The 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.

[0039] The volume average particle diameter (D50) of the pigment, as measured by dynamic light scattering, 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.

[0040] The volume average particle size may be measured, for example, using a Nanotrac Series particle distribution analyzer manufactured by Microtrac Bell Co., Ltd. Methods for adjusting the volume average particle size include, for example, adjusting the degree of pulverization of the pigment before dispersion, adjusting the stirring conditions during dispersion (e.g., stirring speed, stirring temperature, etc.), and adjusting by filtration using a filter after dispersion.

[0041] In order to improve the dispersibility of the pigment in the inkjet ink composition, it is preferable to subject the pigment to a surface treatment or to incorporate a dispersant or the like.

[0042] The surface treatment of the pigment is preferably a physical or chemical treatment in which functional groups such as carbonyl groups, carboxyl groups, aldehyde groups, hydroxyl groups, sulfonic groups, ammonium groups, and salts thereof are directly or indirectly bonded to the surface of the pigment. In particular, the surface treatment is more preferably a treatment in which the pigment surface is oxidized or sulfonated with, for example, ozone, hypochlorous acid, fuming sulfuric acid, or the like to modify the surface of the pigment particles.

[0043] When a dispersant is blended into ink composition A, it is preferable to use a dispersant having a hydrophobic portion (hydrophobic group) and a hydrophilic portion (hydrophilic group) in its molecular structure. Such dispersants have the effect that the hydrophobic portion adsorbs to the surface of the pigment particles and the hydrophilic portion orients toward the aqueous medium side of the inkjet ink composition. This effect tends to make it possible to more stably incorporate the pigment as a dispersion into the inkjet ink composition. Such dispersants are not particularly limited, but examples thereof include acrylic resins, styrene-acrylic resins such as styrene-(meth)acrylic acid copolymers and styrene-(meth)acrylic acid-(meth)acrylate copolymers, styrene-maleic acid resins, and salts thereof, formalin condensates of aromatic sulfonates, etc., and one or more selected from these groups can be used. Note that commercially available dispersants may also be used.

[0044] When the pigment is dispersed using a dispersant, the ratio of the pigment to the dispersant is preferably 10:1 to 1:10, and more preferably 4:1 to 1:3.

[0045] Alternatively, a method of imparting dispersibility by coating pigment particles with a resin or the like may be used. Examples of methods that can be used to coat pigment particles include acid precipitation, phase inversion emulsification, and mini-emulsion polymerization.

[0046] The colorant contained in ink composition A is preferably a water-soluble colorant, as water-soluble colorants tend to have better resolubility / redispersibility when made into an inkjet ink composition.

[0047] The term "water-soluble" in relation to a colorant means that at least a portion of the colorant dissolves in water at 20° C. Preferably, the solubility in water at 20° C. is more than 1 g / 100 g of water, more preferably more than 3 g / 100 g of water, and even more preferably more than 5 g / 100 g of water.

[0048] Examples of water-soluble coloring materials include acid dyes, direct dyes, reactive dyes, and basic dyes.

[0049] The coloring material contained in the ink composition A is preferably a dye. When the coloring material is a dye, there is a tendency for the ink composition to have better resolubility / redispersibility when made into an inkjet ink composition.

[0050] The colorant contained in ink composition A is preferably a reactive dye. Reactive dyes undergo hydrolysis in the presence of water, resulting in the deactivation of reactive groups in the reactive dye. In contrast, the method according to this embodiment tends to reduce the deactivation of reactive groups and achieve good dyeability because ink composition A is mixed with a liquid medium immediately before use in an inkjet printer.

[0051] The content of the colorant is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, relative to the total amount of ink composition A. When the content of the colorant is within the above range, the resolubility / redispersibility when made into an inkjet ink composition tends to be better. The lower limit of the content of the colorant is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, relative to the total amount of ink composition A.

[0052] 1.1.2 Water-soluble solid substances Ink composition A contains a substance that is water-soluble and solid under an environment of 25°C and 1 atmosphere (hereinafter also referred to as a "water-soluble solid substance"). Note that "water-soluble" in the water-soluble solid substance has the same meaning as "water-soluble" in the coloring material described above.

[0053] The water-soluble solid substance may be any substance that is water-soluble and solid under an environment of 25°C and 1 atmospheric pressure, but is preferably at least one selected from the group consisting of a humectant, a surfactant, and a solubilizer, which tends to improve resolubility / redispersibility and intermittent printing stability.

[0054] 1.1.2.1 Moisturizers Ink composition A preferably contains a humectant. The humectant has the function of suppressing evaporation of water, and tends to improve intermittent printing stability when made into an inkjet ink composition, for example.

[0055] Examples of moisturizing agents include ureas. Examples of ureas include urea, ethylene urea, tetramethyl urea, thiourea, etc., and betaines (trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine, N,N,N-trimethylalanine, N,N,N-triethylalanine, N,N,N-triisopropyl ... , N,N-trimethylmethylalanine, carnitine, acetylcarnitine, etc.

[0056] The content of the humectant relative to the total amount of ink composition A is preferably 10 to 70 mass %, more preferably 30 to 60 mass %, even more preferably 40 to 60 mass %, and particularly preferably 50 to 60 mass %.

[0057] 1.1.2.2 Surfactants The ink composition A preferably contains a surfactant, which tends to improve the intermittent printing stability when made into an inkjet ink composition, for example.

[0058] Among surfactants, for example, acetylene glycol surfactants, silicone surfactants, and fluorine surfactants can be preferably used.

[0059] The acetylene glycol surfactant is not particularly limited, but examples thereof include Surfynol 104E, 104H, 104A, 104PA, 104S, and DF110D (all trade names, manufactured by Air Products & Chemicals Co., Ltd.), Olfine 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 Kawaken Fine Chemicals Co., Ltd.).

[0060] The silicone surfactant is not particularly limited, but a polysiloxane compound is preferred. The polysiloxane compound is not particularly limited, but for example, a polyether-modified organosiloxane is exemplified. Commercially available products of the polyether-modified organosiloxane include KF-6004 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0061] As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and specific examples include Surflon S-242 (trade name, manufactured by AGC Seimi Chemical Co., Ltd.) and Futergent 245F (manufactured by Neos Co., Ltd.).

[0062] The content of the surfactant relative to the total amount of ink composition A is preferably 0.1 to 10 mass%, more preferably 0.5 to 8 mass%, even more preferably 0.5 to 5 mass%, and particularly preferably 1 to 3 mass%.

[0063] 1.1.2.3 Solubilizers Ink composition A preferably contains a solubilizer. The term "solubilizer" refers to a substance that promotes the dissolution in water of one or more components of ink composition A. By including a solubilizer, the intermittent printing stability of the ink-jet ink composition tends to be improved.

[0064] 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.

[0065] The content of the solubilizer relative to the total amount of ink composition A is preferably 10 to 50 mass %, more preferably 15 to 40 mass %, even more preferably 15 to 30 mass %, and particularly preferably 15 to 25 mass %.

[0066] Among these, the water-soluble substance that is solid at 25°C and 1 atmospheric pressure is preferably one or more selected from trimethylglycine, urea, and ε-caprolactam, and more preferably contains trimethylglycine, urea, and ε-caprolactam, which tends to improve intermittent printing stability when ink composition A is made into an inkjet ink composition.

[0067] The content of the water-soluble solid substance is preferably 10 to 50 mass % relative to the total amount of ink composition A, more preferably 15 to 40 mass %, even more preferably 15 to 30 mass %, and particularly preferably 15 to 25 mass %.

[0068] 1.1.3 Liquid substances Ink composition A has a content of a liquid substance (hereinafter also referred to as "liquid substance") that is liquid under an environment of 25°C and 1 atmospheric pressure of 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 stability of ink composition A can be improved. Furthermore, the hydrolysis reaction of the colorant can be reduced, thereby achieving good color development. The content of the liquid substance is 20% by mass or less relative to the total amount of ink composition A, but is 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, more particularly preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more particularly preferably none (0% by mass).

[0069] Examples of liquid substances include water and organic solvents, which will be described in detail later.

[0070] 1.1.4 Water-insoluble solid substances Ink composition A preferably contains 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 particularly preferably none (0% by mass) of water-insoluble substances other than colorants that are solid at 25°C and 1 atmospheric pressure, relative to the total amount of ink composition A. If the water-insoluble solid substances are within the above range, intermittent printing stability tends to be improved.

[0071] The term "water-insoluble" refers to something that is not "water-soluble." For example, the term "water-insoluble" refers to a solubility in water at 20°C of 0 g / 100 g of water.

[0072] The water-insoluble solid substance is not particularly limited, but examples thereof include resins and inorganic particles.

[0073] Examples of the resin include urethane 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, phenol resins, silicone resins, epoxy resins, paraffin resins, and fluororesins. The resin may be in the form of, for example, wax or powder, and is preferably in the form of powder.

[0074] Urethane resin is a general term for resins having urethane bonds. In addition to urethane bonds, the urethane resin may be a polyether urethane resin containing ether bonds in the main chain, a polyester urethane resin containing ester bonds in the main chain, or a polycarbonate urethane resin containing carbonate bonds in the main chain.

[0075] Acrylic resin is a general term for polymers obtained by polymerizing at least an acrylic monomer such as (meth)acrylic acid or a (meth)acrylic acid ester as one 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 and vinyl monomers. Further examples include copolymers with vinyl monomers such as styrene. Acrylic monomers that can be used include acrylamide and acrylonitrile.

[0076] Styrene-acrylic resins are copolymers obtained from a styrene monomer and an acrylic monomer, and examples thereof include styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylate copolymer, styrene-α-methylstyrene-acrylic acid copolymer, and styrene-α-methylstyrene-acrylic acid-acrylate copolymer.

[0077] The vinyl chloride resin may be a vinyl chloride-vinyl acetate copolymer.

[0078] The polyolefin resin has an olefin such as ethylene, propylene, or butylene in its structural skeleton, and any known polyolefin resin can be appropriately selected and used.

[0079] The inorganic particles may be any particles that, when contained in the inkjet ink composition (for example, at a content of 3% by mass relative to the total composition), result in a transparent ink color. The term "transparent" refers to a material that allows light to pass through and has extremely high transmittance, allowing light to be seen through the material. Examples of inorganic particles (excluding the coloring materials) include calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass, talc, mica, magnesium oxide, and zinc oxide.

[0080] 1.1.5 Other ingredients In addition to the above components, ink composition A may contain various additives as needed, such as a pH adjuster, wax, chelating agent, rust inhibitor, antifungal agent, antioxidant, anti-reducing agent, evaporation accelerator, etc. The other components may be water-soluble and may be solid at 25°C and 1 atmospheric pressure, or liquid at 25°C and 1 atmospheric pressure.

[0081] The pH adjuster is not particularly limited, and examples thereof include appropriate combinations of acids, bases, weak acids, and weak bases. Examples of acids and bases used in such combinations include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid; inorganic bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate, disodium hydrogen phosphate, potassium carbonate, sodium carbonate, sodium bicarbonate, and ammonia; organic bases such as triethanolamine, diethanolamine, monoethanolamine, tripropanolamine, triisopropanolamine, diisopropanolamine, and trishydroxymethylaminomethane (THAM); and organic acids such as adipic acid, citric acid, succinic acid, lactic acid, and N,N-bis(2-hydroxybenzoate). Other buffers that may be used include Good's buffers such as N-(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), morpholinoethanesulfonic acid (MES), carbamoylmethyliminobisacetic acid (ADA), piperazine-1,4-bis(2-ethanesulfonic acid) (PIPES), N-(2-acetamido)-2-aminoethanesulfonic acid (ACES), cholamine hydrochloride, N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), acetamidoglycine, tricine, glycinamide, and bicine, as well as phosphate buffer, citrate buffer, and Tris buffer.

[0082] When other components are contained, the content thereof is preferably 0.1 to 5 mass % relative to the total amount of ink composition A, more preferably 0.1 to 3 mass %, even more preferably 0.1 to 1 mass %, and particularly preferably 0.3 to 1 mass %.

[0083] 1.1.6 Preparation method The method for preparing ink composition A is not particularly limited, and may be 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, etc. A preferred method for preparing ink composition A is to mix the above-mentioned components with a liquid medium such as water and then freeze-dry or spray-dry the mixture. Freeze drying and spray drying tend to result in a larger surface area of ​​the dried substance compared to natural drying, etc., and therefore tend to result in better resolubility / redispersibility. Furthermore, freeze drying does not apply heat, and spray drying requires only a very short heating time, so heat damage to ink composition A can be reduced.

[0084] The freeze-drying can be carried out using a known freeze-drying device, such as the "FD-1000" manufactured by Tokyo Rikakikai Co., Ltd. The freeze-drying preferably includes a pre-freezing step and a freeze-drying step.

[0085] The pre-freezing step is a step of cooling a sample with a low-temperature liquid. The temperature in the pre-freezing step is not particularly limited, but is preferably −70° C. to −200° C. Examples of the low-temperature liquid used in the pre-freezing step include liquid nitrogen, liquid ethanol, and liquid acetone.

[0086] The freeze-drying process is a process in which the sample is subjected to reduced pressure and left for a predetermined period of time to vaporize the liquid medium in the sample and freeze-dry it. The temperature during the freeze-drying process is not particularly limited, but is preferably set lower than the collapse temperature of the sample to be freeze-dried, and is preferably -80°C or higher. The pressure during the reduced pressure is also not particularly limited, but is preferably 100 mmHg or less, and most preferably 20 mmHg or less. The time for the freeze-drying process is also not particularly limited, but is preferably 2 to 24 hours, and most preferably about 10 hours.

[0087] Spray drying can be carried out using a known spray dryer, such as "ADL311S-A" manufactured by Yamato Scientific Co., Ltd.

[0088] The drying temperatures in spray drying are 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.

[0089] 1.1.7 Storage Ink composition A has a water vapor transmission rate of 5 g / m2 at a temperature of 20°C and a humidity of 90% RH, as measured in accordance with JIS K 7129. 2 It is preferable that the colorant is stored in a container made of a material having a shelf life of 1 / day or less. In this case, the storage property tends to be improved and the deactivation of the colorant tends to be reduced.

[0090] The water vapor permeability measured in accordance with JIS K 7129 at a temperature of 20°C and a humidity of 90% RH is preferably 3 g / m 2 / day or less, and more preferably 2 g / m 2 / day or less.

[0091] Water vapor permeability of 5g / m at a temperature of 20°C and humidity of 90% RH, measured in accordance with JIS K 7129 2 / day or less is preferably a laminate obtained by laminating a resin layer such as polyethylene terephthalate or polypropylene with a barrier layer such as aluminum foil or aluminum vapor deposition film.

[0092] 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 the aqueous solution B. This tends to enable the mixing step described below to be carried out effectively, and to improve resolubility / redispersibility.

[0093] At least one embodiment of the mixing and stirring mechanism will be described. The mixing and stirring mechanism is provided below the container, preferably on the bottom surface of the container. The mixing and stirring mechanism preferably includes a rotor, a rotating shaft, and a motor. The rotor is supported on the rotating shaft that is rotated by the motor, and the rotor rotates when driven by the motor.

[0094] At least one embodiment of the heating mechanism will be described. The heating mechanism may be a heater that comes into contact with ink composition A and aqueous solution B and directly heats them, or a heater that is attached to the outside of the container and heats the container, thereby indirectly heating ink composition A and aqueous solution B. The heater temperature is not particularly limited, but is preferably 30 to 80°C, and more preferably 30 to 60°C.

[0095] The capacity of the container is preferably not more than 20 L, more preferably not more than 10 L. When the capacity of the container is within the above range, the mixing step described below can be carried out effectively, and resolubility / redispersibility tends to be improved.

[0096] 1.2 Aqueous solution B preparation process A method for using an ink according to one embodiment of the present invention includes a step of preparing an aqueous solution B. Each component contained in the aqueous solution B will be described below.

[0097] Aqueous solution B contains water in an amount of 50% by mass or more relative to the total amount of aqueous solution B. This makes it possible to improve the intermittent printing stability.

[0098] 1.2.1 Water Aqueous solution B contains water. The water is not particularly limited, but examples thereof include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water, from which ionic impurities have been removed as much as possible. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can prevent the growth of mold and bacteria when aqueous solution B is stored for a long period of time.

[0099] The water content is 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, more particularly preferably 95% by mass or more, and especially preferably 100% by mass, relative to the total amount of aqueous solution B. In particular, when aqueous solution B contains water in an amount of 60% by mass or more relative to the total amount of aqueous solution B, intermittent printing stability tends to be improved.

[0100] 1.2.2 Organic solvents The aqueous solution B may contain an organic solvent. Examples of the organic solvent include esters, alkylene glycol ethers, cyclic esters, amides, alcohols, and polyhydric alcohols.

[0101] Examples of esters include 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, Examples of the glycol monoacetates include propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate; and glycol diesters include 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.

[0102] The alkylene glycol ethers may be monoethers or diethers of alkylene glycol, 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, tripropylene glycol monobutyl ether, and the like. alkylene glycol monoalkyl 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, tripropylene glycol dimethyl ether, and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0103] Examples of cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen atom of the methylene group adjacent to the carbonyl group of these cyclic esters is substituted with an alkyl group having 1 to 4 carbon atoms.

[0104] Examples of the amides include cyclic amides and non-cyclic amides. Examples of the non-cyclic amides include alkoxyalkyl amides.

[0105] Examples of cyclic amides include lactams, such as 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)pyrrolidin-2-one.

[0106] Examples of 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-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, Examples of the propionamide include propionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso-propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N-methylethylpropionamide, and N,N-dimethylisobutyric acid amide.

[0107] Examples of alcohols include compounds in which one hydrogen atom of an alkane has been substituted with a hydroxyl group. The alkane preferably has 10 or fewer carbon atoms, more preferably 6 or fewer carbon atoms, and even more preferably 3 or fewer carbon atoms. The alkane has 1 or more carbon atoms, preferably 2 or more carbon atoms. The alkane may be linear or branched. Examples of alcohols include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol, 2-phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0108] Polyhydric alcohols have two or more hydroxyl groups in the molecule and can be divided into, for example, alkanediols and polyols.

[0109] Examples of alkanediols include compounds in which an alkane is substituted with two hydroxyl groups, such as 1,2-alkanediol, which is a general term for compounds in which hydroxyl groups are substituted at the 1st and 2nd positions of an alkane, and alkanediols other than 1,2-alkanediol.

[0110] Examples of 1,2-alkanediols include ethylene glycol, 1,2-propanediol (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, and 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, and the like.

[0111] Other alkanediols include, for example, 1,3-propanediol, 1,3-butylene glycol (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.

[0112] Examples of polyols include condensates in which two or more molecules of alkanediols are intermolecularly condensed via the hydroxyl groups thereof, and compounds having three or more hydroxyl groups.

[0113] Examples of condensates in which two or more molecules of alkanediols are intermolecularly condensed via the hydroxyl groups thereof include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0114] The compound having three or more hydroxyl groups is a compound having an alkane or polyether structure as a backbone and having three or more hydroxyl groups, such as glycerin, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylenetriol.

[0115] The organic solvents may be used alone or in combination of two or more.

[0116] Among organic solvents, the aqueous solution B preferably contains a water-soluble organic solvent. When a water-soluble organic solvent is contained, the aqueous solution B tends to have good wettability with respect to the ink composition A and to have better resolubility / redispersibility. Note that the "water-soluble" in the water-soluble organic solvent has the same meaning as the "water-soluble" in the colorant described above.

[0117] The water-soluble organic solvent preferably contains one or more selected from glycerin, 1-(2-hydroxyethyl)pyrrolidin-2-one, triethylene glycol, and triethylene glycol monobutyl ether. When such a water-soluble organic solvent is contained, the resolubility / redispersibility tends to be better.

[0118] The content of the organic solvent is preferably 50% by mass or less, more preferably less than 50% by mass, even more preferably 10 to 45% by mass, particularly preferably 20 to 45% by mass, and even more particularly preferably 30 to 45% by mass, relative to the total amount of aqueous solution B.

[0119] Aqueous solution B preferably contains 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more of an organic solvent having a normal boiling point of above 280°C relative to the total amount of aqueous solution B. This tends to result in better resolubility / redispersibility. Examples of organic solvents having a normal boiling point of above 280°C include triethylene glycol and glycerin.

[0120] 1.2.3 Surfactants The aqueous solution B may contain a surfactant. In addition to the surfactants described above, the aqueous solution B may contain a surfactant that is liquid at 25°C and 1 atmosphere. Examples of surfactants that are liquid at 25°C and 1 atmosphere include Olfine PD-002W (an acetylene glycol surfactant, a product name manufactured by Nissin Chemical Industry Co., Ltd.), BYK-348 (a silicone surfactant, a product name manufactured by BYK), and Surflon S-241 (a fluorine-based surfactant, a product name manufactured by AGC Seimi Chemical Co., Ltd.).

[0121] The content of the surfactant is preferably 0.1 to 5 mass % relative to the total amount of aqueous solution B, more preferably 0.1 to 3 mass %, even more preferably 0.3 to 2 mass %, and particularly preferably 0.3 to 1 mass %.

[0122] 1.2.4 Other ingredients In addition to the above components, aqueous solution B may contain various additives such as resins, waxes, chelating agents, rust inhibitors, antifungal agents, antioxidants, and antireducing agents, as needed.

[0123] 1.2.5 Preparation method The method for preparing aqueous solution B is not particularly limited, and can be obtained by mixing the above-mentioned components in any order and removing impurities by filtration, etc., as necessary. A suitable method for mixing the components is to add the materials sequentially 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 used as necessary.

[0124] 1.3 Mixing process A 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 described above when used in an inkjet printer. This makes it possible to minimize the environmental impact of transportation and the storage space required.

[0125] The mixing step is a step that is carried out incidentally when the inkjet printer is used, and may be carried out immediately before the inkjet printer is used, or may be carried out while the inkjet printer is being used.

[0126] Immediately before using the inkjet printer means, for example, up to one week, up to three days, up to one day, up to 12 hours, up to six hours, up to three hours, up to one hour, up to 30 minutes, up to 15 minutes, or up to five minutes before using the inkjet printer.

[0127] The mixing step may be performed within the inkjet printer, or may be performed in a container separate from the inkjet printer, or may be performed within 100 m, 50 m, 25 m, 10 m, 5 m, or 1 m of the inkjet printer.

[0128] The method for mixing the ink composition A and the aqueous solution B is not particularly limited, but may be, for example, a method in which the ink composition A and the aqueous solution B are added to a container equipped with a stirring device and stirred to mix them.

[0129] The mixing ratio of the ink composition A and the aqueous solution B can be adjusted appropriately depending on the purpose. For example, the mass ratio of the ink composition A to the aqueous solution B (ink composition A / aqueous solution B) is preferably 0.25 to 1.5, and more preferably 0.25 to 1.2. It is more preferably 0.25 to 1.0, and particularly preferably 0.3 to 0.9.

[0130] The inkjet ink composition C obtained by the mixing step has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less, which allows for good resolubility / redispersibility and intermittent printing stability.

[0131] 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. There is no particular lower limit to the surface tension, but it is preferably 25 mN / m or more, more preferably 30 mN / m or more.

[0132] 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, even more preferably 15 mPa·s or less, particularly preferably 10 mPa·s or less, and more particularly preferably 5 mPa·s or less.

[0133] 1.4 Inkjet printer A method of using an ink according to one embodiment of the present invention involves ejecting the above-described ink-jet ink composition C from an ink-jet printer. The ink-jet printer will now be described with reference to the drawings.

[0134] The inkjet printer preferably has an inkjet head equipped with a nozzle for ejecting the inkjet ink composition, a pressure chamber to which the inkjet ink composition is supplied, and a circulation flow path that allows the inkjet ink composition in the pressure chamber to circulate, which tends to improve intermittent printing stability.

[0135] As shown in Fig. 1, the inkjet head 10 has a nozzle 1, a pressure chamber 2 to which an inkjet ink composition is supplied, and a circulation channel 3 that enables the inkjet ink composition to circulate in the pressure chamber 2. In the example shown in Fig. 1, the nozzle 1 and the pressure chamber 2 are in communication with each other via a communication channel 4.

[0136] The nozzle 1 is a through-hole for ejecting the ink-jet ink composition. More specifically, the nozzle 1 is a through-hole formed in a nozzle plate. The nozzle plate has a plurality of nozzles formed therein, and a pressure chamber 2 is provided for each nozzle. A pressure chamber 2 is formed individually for each nozzle 1. The ink-jet ink composition is supplied to the pressure chamber 2. When the pressure in the pressure chamber 2 fluctuates due to a pressure generating means (not shown), a portion of the ink-jet ink composition flowing through the communication channel 4 is ejected to the outside from the nozzle 1, and the remaining portion flows into the circulation channel 3. The path of the circulation channel 3 is not particularly limited, but the channel can be configured so that the ink-jet ink composition that flows into the circulation channel 3 is supplied to the pressure chamber 2. Note that the ink-jet ink composition that flows into the circulation channel 3 does not necessarily have to be re-supplied to the same pressure chamber, but may be supplied to a pressure chamber corresponding to another nozzle. Furthermore, all of the circulation channel 3 does not need to be located inside the ink-jet head 10; some of the channels can be located outside the ink-jet head 10, as long as the ink-jet ink composition that flows out of the pressure chamber 2 is supplied again to the pressure chamber 2.

[0137] As described above, the inkjet head 10 of this embodiment allows the inkjet ink composition in the pressure chambers 2, more specifically, the inkjet ink composition in the vicinity of the nozzles 1, to be efficiently circulated within the head. This tends to improve intermittent printing stability.

[0138] The inkjet head 10 may be, for example, a line head that performs printing by a line method, or a serial head that performs printing by a serial method.

[0139] In the line method using a line head, for example, an inkjet head having a width equal to or greater than the recording width of the recording medium is fixed to the inkjet printer. The recording medium is then moved in the sub-scanning direction (the longitudinal direction of the recording medium, the transport direction), and ink droplets are ejected from the nozzles of the inkjet head in conjunction with this movement to record an image on the recording medium.

[0140] In the serial method using a serial head, for example, an inkjet head is mounted on a carriage that can move in the width direction of the recording medium. The carriage is then moved in the main scanning direction (the horizontal or width direction of the recording medium), and ink droplets are ejected from the nozzle openings of the head in conjunction with this movement, thereby recording an image on the recording medium.

[0141] The recording medium is not particularly limited, and examples thereof include liquid-absorbent recording media such as paper, film, and cloth, low-liquid-absorbent recording media such as printing paper, and non-liquid-absorbent recording media such as metal, glass, and polymers. The form of the recording medium is also not particularly limited, and examples thereof include film, board, and cloth.

[0142] The inkjet head 10 may have a heating unit capable of heating the inkjet ink composition. More specifically, the inkjet head 10 may have a heating unit that heats the inkjet ink composition in a circulation flow path composed of the pressure chamber 2, the circulation flow path 3, and the connecting path 4. The heating means is not particularly limited, and may be provided, for example, in the pressure chamber 2, the circulation flow path 3, or the connecting path 4. In addition, a heating means for heating the nozzle plate may be provided, or, in the case where the circulation flow path 3 passes through an area outside the inkjet head 10, a heating means may be provided in the circulation flow path 3 located outside the inkjet head 10. Furthermore, a heating means may be provided in an ink flow path upstream of the pressure chamber. Here, the ink flow path refers to a flow path for distributing ink. The ink flow path also includes, for example, an ink supply path for supplying ink from an ink storage container that stores ink to the inkjet head.

[0143] The heating temperature of the composition is preferably 35° C. or higher, more preferably 40° C. or higher, and even more preferably 45° C. or higher, and is preferably 70° C. or lower, more preferably 60° C. or lower, and even more preferably 50° C. or lower.

[0144] 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 the aqueous solution B. This makes it possible to carry out the above-mentioned mixing step effectively, and tends to improve resolubility / redispersibility.

[0145] At least one embodiment of the mixing and stirring mechanism will be described. The mixing and stirring mechanism is preferably provided below the ink containing container of the ink jet printer, preferably on the bottom surface of the ink containing container. The mixing and stirring mechanism preferably includes a rotor, a rotating shaft, and a motor. The rotor is supported on the rotating shaft that is rotated by the motor, and the rotor rotates when driven by the motor.

[0146] At least one embodiment of the heating mechanism will be described. The heating mechanism may be a heater that is in contact with ink composition A and aqueous solution B and directly heats them, or a heater that is attached to the outside of an ink container and heats the ink container, thereby indirectly heating ink composition A and aqueous solution B. The heater temperature is not particularly limited, but is preferably 30 to 80°C, and more preferably 30 to 60°C.

[0147] As an example of an inkjet printer, a perspective view of a serial printer is shown in Figure 2. As shown in Figure 2, the serial printer 20 includes a conveying unit 220 and a recording unit 230. The conveying unit 220 conveys the recording medium F fed to the serial printer to the recording unit 230, and ejects the recording medium after recording outside the serial printer. Specifically, the conveying unit 220 has feed rollers and conveys the fed recording medium F in the sub-scanning direction T1.

[0148] The recording unit 230 also includes an inkjet head 231 that ejects a composition onto the recording medium F sent from the conveying unit 220, a carriage 234 that carries the inkjet head 231, and a carriage movement mechanism 235 that moves the carriage 234 in the main scanning directions S1 and S2 of the recording medium F.

[0149] In the case of a serial printer, an inkjet head 231 having a length smaller than the width of the recording medium is provided, and the head moves to perform recording in multiple passes (multi-pass). In a serial printer, the head 231 is mounted on a carriage 234 that moves in a predetermined direction, and the head moves in conjunction with the movement of the carriage, thereby ejecting the composition onto the recording medium. In this way, recording is performed in two or more passes (multi-pass). A pass is also called a main scan. A sub-scan is performed to transport the recording medium between passes. In other words, main scans and sub-scans are performed alternately.

[0150] The inkjet printer is not limited to the serial type printer, but may be the line type printer described above.

[0151] 2. Ink set An ink set according to one embodiment of the present invention comprises ink composition A, which contains a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less relative to the total amount of ink composition A, and aqueous solution B, which contains water at 50 mass% or more relative to the total amount of aqueous solution B, and which is mixed with ink composition A so that the surface tension is 40 mN / m or less and the viscosity is 100 mPa s or less.

[0152] According to the ink set of this embodiment, the dry ink composition and the water-soluble solution can be mixed immediately before use in an inkjet printer to produce an inkjet ink, thereby minimizing the environmental impact of transportation and the storage space required. Furthermore, the dry ink composition contains a colorant and a water-soluble solid substance, thereby improving resolubility / redispersibility, and the water-soluble solution contains water in an amount of 50% by mass or more relative to the total amount of the water-soluble solution, thereby improving intermittent printing stability. Furthermore, by adjusting the surface tension and viscosity of the inkjet ink composition after mixing to predetermined values, inkjet ejection can be stabilized.

[0153] In the present invention, an "ink set" refers to a set of inks that combines at least ink composition A and aqueous solution B. An ink set is a set of inks that are mixed together for use. The ink set may contain only one ink composition, or may contain two or more ink compositions. The same applies to the aqueous solution contained in the ink set.

[0154] The ink composition A and aqueous solution B contained in the ink set according to this embodiment are as described above, and therefore a description thereof will be omitted.

[0155] 3. Method for producing inkjet ink composition A method for producing an ink-jet ink composition according to one embodiment of the present invention comprises producing an ink-jet ink composition comprising a colorant and a substance that is water-soluble and solid at 25°C and 1 atmospheric pressure, wherein the content of the substance that is liquid at 25°C and 1 atmospheric pressure is greater than or equal to the total content of the substance in ink composition A. The method includes a step of mixing, when used in an inkjet printer, ink composition A, which contains 20% by mass or less of water based on the total amount of aqueous solution B, with aqueous solution B, which contains 50% by mass or more of water based on the total amount of aqueous solution B, wherein the inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa s or less.

[0156] According to the method for producing an inkjet ink composition according to this embodiment, the dry ink composition and the aqueous solution can be mixed immediately before use in an inkjet printer to produce an inkjet ink, thereby minimizing the environmental impact of transportation and the storage space required. Furthermore, the dry ink composition contains a colorant and a water-soluble solid substance, thereby improving resolubility / redispersibility, and the aqueous solution contains water in an amount of 50% by mass or more relative to the total amount of the aqueous solution, thereby improving intermittent printing stability. Furthermore, by adjusting the surface tension and viscosity of the inkjet ink composition after mixing to predetermined values, inkjet ejection can be stabilized.

[0157] The ink composition A and 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 mixing step described above, so a description thereof will be omitted.

[0158] 4. Inkjet ink composition An inkjet ink composition according to one embodiment of the present invention comprises: ink composition A, which contains a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less relative to the total amount of ink composition A; and aqueous solution B, which contains water in an amount of 50 mass% or more relative to the total amount of aqueous solution B; and the inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa s or less.

[0159] The inkjet ink composition according to this embodiment can be obtained by mixing the dry ink composition and the water-soluble solution immediately before use in an inkjet printer, thereby minimizing the environmental impact of transportation and the storage space required. Furthermore, the dry ink composition contains a colorant and a water-soluble solid substance, thereby improving resolubility / redispersibility. The water-soluble solution contains water in an amount of 50% by mass or more relative to the total amount of the water-soluble solution, thereby improving intermittent printing stability. Furthermore, by adjusting the surface tension and viscosity of the inkjet ink composition after mixing to predetermined values, inkjet ejection can be stabilized.

[0160] The ink composition A and the aqueous solution B that constitute the inkjet ink composition according to this embodiment are as described above, and therefore a description thereof will be omitted.

[0161] The ratio of ink composition A to aqueous solution B can be adjusted appropriately depending on the purpose, but 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, even more preferably 0.25 to 1.0, and particularly preferably 0.3 to 0.9.

[0162] 5. Working Example The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" below is based on mass.

[0163] 5.1 Preparation of ink composition The components were placed in a container so as to obtain the composition shown in Table 1, and mixed and stirred for 2 hours using a magnetic stirrer. After that, the components were further dispersed in a bead mill filled with zirconia beads having a diameter of 0.3 mm to thoroughly mix them. After stirring for 1 hour, the mixture was filtered using a 5 μm PTFE membrane filter to obtain each pre-drying ink. The coloring material used to prepare the ink 3 before drying was a water-soluble styrene-acrylic resin. The pigment dispersion was prepared by mixing the pigment dispersant (not shown in the table) with water in a mass ratio of 2:1 (pigment:pigment dispersant) and thoroughly stirring to prepare a pigment dispersion, which was then used to prepare the ink. The colorant column shows the mass % of the pigment converted from the solids concentration of the pigment dispersion.

[0164] Each of the obtained pre-drying inks was dried using the ink drying methods shown in Tables 4 and 5 to obtain each of the dried inks shown in Table 2. Specifically, freeze-drying was performed using an apparatus model number "FD-1000" (manufactured by Tokyo Rikakikai Co., Ltd.) by placing 30 g of pre-dried ink in a 50 ml screw tube and performing freeze-drying at a trap cooling temperature of -45°C for 10 hours (additional drying was performed if drying was not complete), to obtain each dried ink. In addition, spray drying was carried out using an organic solvent recovery device "GAS410" (manufactured by Yamato Scientific Co., Ltd.) in an apparatus model number "ADL311S-A" (manufactured by Yamato Scientific Co., Ltd.) under conditions of an inlet temperature of 200°C and an outlet temperature of 60°C, to obtain dried ink 1 relating to Example 3. Furthermore, the ink was left to dry naturally in an open state in an environment of 25° C. and 40% RH for 30 days, to obtain dried ink 1 according to Example 18.

[0165] The following is a supplementary explanation of Tables 1 and 2. Surfynol 104E (trade name of Air Products & Chemicals, an acetylene glycol surfactant) Styrene-acrylic resin (Nippon Paint Industrial Coatings Group) AS Resin Co., Ltd. Product name "FS-102")

[0166] 5.2 Preparation of aqueous solutions 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.

[0167] The following is a supplementary explanation of Table 3. Olfine PD002W (product name of Nissin Chemical Industry Co., Ltd., acetylene glycol surfactant)

[0168] 5.3 Preparation of Inkjet Ink Composition The inkjet ink compositions of each example were obtained by mixing the dried ink and aqueous solution obtained above in the combinations and mixing ratios shown in Tables 4 and 5. Specifically, the dried ink and aqueous solution were placed in a container shown in Tables 4 and 5, and mixed and stirred for 1 hour at 60°C and a stirring speed of 350 rpm if the container had a heating / stirring mechanism, or mixed and stirred manually using a stirring rod if the container did not have a heating / stirring mechanism, thereby obtaining the inkjet ink compositions of each example. In Example 6, the dried ink and aqueous solution were directly charged into an ink tank capable of charging, heating, and stirring liquids, and into the ink tank of a Seiko Epson Corporation inkjet printer "PX-G930" modified so that the ink composition could be supplied from the ink tank to a print head, and the ink and aqueous solutions were mixed and stirred at 60°C for 1 hour at a stirring speed of 350 rpm, to obtain an inkjet ink composition. In Example 19, after drying, the ink and aqueous solution were placed in a container and mixed and stirred for 1 hour at 60°C and a stirring speed of 350 rpm. The composition in the container was then placed in a Seiko Epson Corporation inkjet printer "PX-G930" that had been modified as described above, and mixed and stirred for 1 hour at 60°C and a stirring speed of 350 rpm, thereby obtaining an inkjet ink composition.

[0169] For the inkjet ink compositions obtained according to each example, the surface tension was measured by the Wilhelmy method using a surface tensiometer (DY-300, manufactured by Kyowa Interface Science Co., Ltd.), and the viscosity was measured in accordance with JIS Z8809 using a vibration viscometer (VM-100, manufactured by Senicook Co., Ltd.). The results are shown in Tables 4 and 5.

[0170] 5.4 Evaluation Method 5.4.1 Redispersibility / Redispersibility The peak value of the absorbance in the visible light region of the ink before drying obtained above was taken as 100% (in the case of a colorant without a peak, the value at a wavelength of 500 nm was taken as 100%), and the peak of the absorbance of the inkjet ink composition obtained above was measured in the same manner to determine the value of (peak value of inkjet ink composition) / (peak value of ink before drying), and the resolubility / redispersibility was evaluated based on the following criteria. (Judgment criteria) A+: 98% or higher A: 95% or more but less than 98% B: 90% or more but less than 95% C: Less than 95%

[0171] 5.4.2 Intermittent printing stability The inkjet ink composition obtained above was filled into an inkjet printer "PX-G930" manufactured by Seiko Epson Corporation, and the inkjet head was allowed to idle for 2 minutes in an environment of 40°C and 20% RH. After that, the percentage of nozzles that could not eject ink normally was determined, and the intermittent printing stability was evaluated based on the following criteria. (Judgment criteria) A+: Less than 5% A: 5% or more but less than 10% B: 10% or more but less than 20% C: 25% or more

[0172] 5.4.3 Storage The dried ink obtained above was placed in a container as shown in Tables 4 and 5 and left at 30°C and 90% RH for 3 hours. The increase in moisture content was calculated from the difference in weight before and after leaving the ink, and the storage stability was evaluated based on the following criteria. (Judgment criteria) A: 0.5% or less B: Over 0.5% and 1% or less C: More than 1%

[0173] 5.4.4 Inactivation Stability An inkjet ink composition was obtained in the same manner as in "5.3 Preparation of Inkjet Ink Composition," except that the dried ink obtained above was left in a container at 60°C and 50% RH for 10 days. A printed textile was prepared using this inkjet ink composition (reactive dye: cotton, acid dye: silk, pigment: polyester), and the color difference ΔEcmc2:1 between this inkjet ink composition and a printed textile prepared in the same manner using the dried ink that was not left at 60°C and 50% RH for 10 days was determined, and the deactivation stability was evaluated based on the following criteria. (Judgment criteria) A: 4 or more B: 2 or more but less than 4 C: Less than 2

[0174] 5.4.5 Water Solubility The water solubility shown in Tables 1 to 3 was evaluated based on the following criteria. (Judgment criteria) A: 5wt% or more B: More than 0 wt% and less than 5 wt% C: Insoluble. 0wt%

[0175] 5.5 Evaluation results The evaluation results are shown in Tables 4 and 5. In each example relating to a method of using the ink in an inkjet printer, ink composition A, which contains a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, where the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less, based on the total amount of ink composition A, and aqueous solution B, which contains water at 50 mass% or more, based on the total amount of aqueous solution B, were mixed to obtain inkjet ink composition C, which after mixing had a surface tension of 40 mN / m or less and a viscosity of 100 mPa s or less, and which was then ejected from the inkjet printer for use, all of the examples showed excellent resolubility / redispersibility, intermittent printing stability, and storage properties.

[0176] In contrast, when the inks according to the comparative examples were used in a manner that did not satisfy the above-mentioned requirements, at least one of resolubility / redispersibility, intermittent printing stability, and storage stability was poor.

[0177] The following can be derived from the above-described embodiment.

[0178] One aspect of the method of using the ink is an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; an aqueous solution B containing water in an amount of 50 mass% or more relative to the total amount of the aqueous solution B; When used in inkjet printers, After mixing, an ink-jet ink composition C having a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less is obtained, and is ejected from the ink-jet printer.

[0179] In one embodiment of the method for using the ink, The coloring material may be a water-soluble coloring material.

[0180] In any one of the above-described methods for using the ink, The coloring material may be a dye.

[0181] In any one of the above-described methods for using the ink, The coloring material may be a reactive dye.

[0182] In any one of the above-described methods for using the ink, The substance that is water-soluble and solid at 25° C. and 1 atmospheric pressure may be one or more selected from a moisturizer, a surfactant, and a solubilizer.

[0183] In any one of the above-described methods for using the ink, The substance that is water-soluble and solid at 25° C. and under atmospheric pressure may be one or more selected from trimethylglycine, urea, and ε-caprolactam.

[0184] In any one of the above-described methods for using the ink, The ink composition A may contain 1% by mass or less of a water-insoluble substance other than the coloring material that is solid at 25° C. and 1 atmospheric pressure, relative to the total amount of the ink composition A.

[0185] In any one of the above-described methods for using the ink, The content of the coloring material may be 35% by mass or less relative to the total amount of the ink composition A.

[0186] In any one of the above-described methods for using the ink, The ink composition A may be produced by freeze-drying or spray-drying.

[0187] In any one of the above-described methods for using the ink, The aqueous solution B may contain water in an amount of 60 mass % or more based on the total amount of the aqueous solution B.

[0188] In any one of the above-described methods for using the ink, The aqueous solution B may further contain a water-soluble organic solvent.

[0189] In any one of the above-described methods for using the ink, The inkjet printer may include 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.

[0190] In any one of the above-described methods for using the ink, The ink composition A has a water vapor transmission rate of 5 g / m2 at a temperature of 20°C and a humidity of 90% RH, as measured in accordance with JIS K 7129. 2 It may be stored in a container constructed of a material that is rated for less than 1 / day.

[0191] In the embodiment of the method for using the ink, The container may include 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.

[0192] In any one of the above-described methods for using the ink, The container may have a capacity of 20 L or less.

[0193] In any one of the above-described methods for using the ink, The inkjet printer may have an inkjet head including a nozzle for ejecting the inkjet ink composition C, a pressure chamber to which the inkjet ink composition C is supplied, and a circulation flow path that allows the inkjet ink composition C to circulate in the pressure chamber.

[0194] One aspect of the ink set is an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; and an aqueous solution B containing water in an amount of 50% by mass or more based on the total amount of the aqueous solution B, The ink composition A and the aqueous solution B are mixed together so that the surface tension is 40 mN / m or less and the viscosity is 100 mPa·s or less.

[0195] One embodiment of a method for producing an inkjet ink composition comprises: 1. A method for making an inkjet ink composition, comprising: an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; and an aqueous solution B containing water in an amount of 50% by mass or more relative to the total amount of the aqueous solution B, when used in an inkjet printer, The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0196] One embodiment of the inkjet ink composition comprises: an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the liquid substance at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; an aqueous solution B containing water in an amount of 50 mass% or more based on the total amount of the aqueous solution B; An inkjet ink composition comprising: The inkjet ink composition has a surface tension of 40 mN / m or less and a viscosity of 100 mPa·s or less.

[0197] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments, such as configurations with the same functions, methods, and results, or configurations with the same purpose and effects. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments. [Explanation of symbols]

[0198] 1... nozzle, 2... pressure chamber, 3... circulation flow path, 4... communication path, 10, 231... inkjet head, 20... serial printer, 220... transport unit, 230... recording unit, 234... carriage, 235... carriage movement mechanism, F... recording medium, S1, S2... main scanning direction, T1... sub-scanning direction

Claims

1. an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the substance that is liquid at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; an aqueous solution B containing water in an amount of 50 mass% or more relative to the total amount of the aqueous solution B; When used in inkjet printers, A method for using an ink, comprising obtaining an ink-jet 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 discharging the ink from the ink-jet printer.

2. The method of claim 1 , wherein the colorant is a water-soluble colorant.

3. The method of claim 1 wherein the colorant is a dye.

4. The method of claim 3 wherein the colorant is a reactive dye.

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

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

7. The method according to claim 1 , wherein the ink composition A contains 1% by mass or less of a water-insoluble substance other than the colorant that is solid at 25° C. and 1 atmospheric pressure, relative to the total amount of the ink composition A.

8. The method according to claim 1 , wherein 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 of claim 1 , wherein the ink composition A is produced by freeze-drying or spray-drying.

10. The method according to claim 1 , wherein the aqueous solution B contains water in an amount of 60% by mass or more based on the total amount of the aqueous solution B.

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

12. 2. The method according to claim 1, wherein 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 ink composition A has a water vapor permeability of 5 g / m under an environment of a temperature of 20° C. and a humidity of 90% RH, as measured in accordance with JIS K 7129. ２ 10. The method of claim 1, wherein the food is stored in a container made of a material having a shelf life of 100 days or less.

14. The method according to claim 13 , wherein 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. 15. The method of claim 13 or claim 14, wherein the volume of the container is 20 L or less.

16. 2. The method according to claim 1, wherein the inkjet printer has an inkjet head including a nozzle for ejecting the inkjet ink composition C, a pressure chamber to which the inkjet ink composition C is supplied, and a circulation flow path that allows the inkjet ink composition C to circulate in the pressure chamber.

17. an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the substance that is liquid at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; an aqueous solution B containing water in an amount of 50% by mass or more based on the total amount of the aqueous solution B, The ink set includes a mixture of 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. 1. A method for making an inkjet ink composition, comprising: an ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the substance that is liquid at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; and an aqueous solution B containing water in an amount of 50% by mass or more based on the total amount of the aqueous solution B, when used in an inkjet printer; 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 ink composition A containing a colorant and a water-soluble substance that is solid at 25°C and 1 atmospheric pressure, wherein the content of the substance that is liquid at 25°C and 1 atmospheric pressure is 20 mass% or less with respect to the total amount of the ink composition A; an aqueous solution B containing water in an amount of 50 mass% or more based on the total amount of the aqueous solution B; An inkjet ink composition comprising: 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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