Inkjet ink composition and inkjet recording method

Abstract

To provide an inkjet ink composition that exhibits excellent clogging recovery and excellent continuous ejection stability. [Solution] An inkjet ink composition according to one embodiment of the present invention is an inkjet ink composition containing a colorant, an organic solvent, and water, wherein the organic solvent contains triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, and one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam.

Description

Technical Field

[0001] The present invention relates to an inkjet ink composition and an inkjet recording method.

Background Art

[0002] The inkjet recording method can record high-definition images with a relatively simple device and has been rapidly developing in various fields. Among them, the solvent used in the ink composition has been studied so as to be suitable for the inkjet recording method.

[0003] For example, Patent Document 1 describes a solvent-based inkjet ink composition containing tetraethylene glycol monobutyl ether as an organic solvent.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is a problem in achieving both clogging recovery and continuous ejection stability.

Means for Solving the Problems

[0006] One aspect of the inkjet ink composition according to the present invention is an inkjet ink composition containing a coloring material, an organic solvent, and water, wherein the organic solvent contains triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, and at least one selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam.

[0007] One aspect of the inkjet recording method according to the present invention is: The process includes ejecting the inkjet ink composition according to one embodiment described above from an inkjet head and adhering it to a recording medium. [Brief explanation of the drawing]

[0008] [Figure 1] Table 1 shows examples of inkjet ink compositions for each example and their evaluation results. [Figure 2] Table 2 shows the composition examples and evaluation results of the inkjet ink compositions for each example and comparative example. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below. The embodiments described below are examples of the present invention. The present invention is not limited in any way to the embodiments described below, and includes various modifications that can be implemented without changing the gist of the present invention. Not all of the configurations described below are necessarily essential to the present invention.

[0010] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, "(meth)acrylic" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate.

[0011] 1. Inkjet ink composition An inkjet ink composition according to one embodiment of the present invention is an inkjet ink composition containing a colorant, an organic solvent, and water, wherein the organic solvent contains triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, and one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam.

[0012] Triethylene glycol monobutyl ether (hereinafter also referred to as "BTG") has an alkoxy group and is therefore relatively hydrophobic. For this reason, including BTG can improve the solubility and dispersibility of colorants in water-based inkjet ink compositions, making precipitation and solidification of colorants less likely. As a result, the clogging recovery properties of water-based inkjet ink compositions can be improved.

[0013] On the other hand, BTG has a tendency to increase the viscosity of water-based inkjet ink compositions. When the viscosity of the inkjet ink composition increases, ejection from the inkjet head may become unstable.

[0014] The present inventors have conducted diligent research and have discovered that by including tetraethylene glycol monobutyl ether (hereinafter also referred to as "BTeG") and one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam in addition to BTG, the ejection stability of the inkjet ink composition can be improved. It is presumed that the mixing of BTG and BTeG reduced the viscosity increase caused by BTG while improving the solubility and dispersibility of the colorant. Furthermore, it is presumed that the inclusion of one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam mitigated the high hydrophobicity of BTG and BTeG, resulting in a good balance of hydrophilicity and hydrophobicity in the water-based ink components and excellent continuous dispensing stability.

[0015] Therefore, according to the inkjet ink composition of this embodiment, the solubility and dispersibility of the colorant are good, the clogging recovery is excellent, and the continuous ejection stability is also excellent.

[0016] The components contained in the inkjet ink composition according to this embodiment will be described below.

[0017] 1.1 Colorants The inkjet ink composition according to this embodiment contains a coloring material. Examples of the coloring material include dyes and pigments.

[0018] 1.1.1 Dyes Examples of the dyes include water-soluble dyes and disperse dyes.

[0019] It is preferable that the coloring material contained in the inkjet ink composition according to this embodiment includes a water-soluble dye. When the coloring material includes a water-soluble dye, precipitation and solidification of the coloring material are less likely to occur, and it is easier to better balance hydrophilicity and hydrophobicity in the ink components. Therefore, the clogging recovery property and continuous ejection stability tend to be further improved.

[0020] As the water-soluble dye, various water-soluble dyes can be used. For example, acid dyes, direct dyes, and reactive dyes can be mentioned. In the inkjet ink composition according to this embodiment, it is preferable that the water-soluble dye is one kind or more selected from acid dyes, direct dyes, and reactive dyes. When the water-soluble dye is one kind or more selected from these, precipitation and solidification of the coloring material are less likely to occur, and it is easier to better balance hydrophilicity and hydrophobicity in the ink components. Therefore, the clogging recovery property and continuous ejection stability tend to be further improved.

[0021] Examples of acid dyes include CIAcid Red 1, 6, 8, 9, 13, 14, 18, 19, 24, 26, 27, 28, 32, 35, 37, 42, 51, 52, 57, 62, 75, 77, 80, 82, 83, 85, 87, 88, 89, 92, 94, 95, 97, 106, 111, 114, 115, 117, 118, 119, 127, 128, 129, 130, 131, 133, 134, 138, 143, 145, 149, 151, 154, 155, 158, 168, 180, 183, 184, 186, 194, 198, 199, 209, 211, 215, 216, 217, 219, 249, 252, 254, 256, 257, 260, 261, 262, 263, 265, 266, 274, 276, 282, 283, 289, 299, 301, 303, 305, 315, 318, 320, 321, 322, 336, 337, 361, 396, 397; CIAcid Violet 5, 7, 11, 15, 31, 34, 35, 41, 43, 47, 48, 49, 51, 54, 66, 68, 75, 78, 90, 97, 103, 106, 126; CIAcid Yellow 1, 3, 7, 11, 17, 19, 23, 25, 29, 36, 38, 39, 40, 42, 44, 49, 50, 59, 61, 64, 70, 72, 75, 76, 78, 79, 98, 99, 110, 111, 112, 114, 116, 118, 119, 1 27, 128, 131, 135, 141, 142, 143, 151, 159, 161, 162, 163, 164, 165, 169, 174, 184, 190, 195, 196, 197, 199, 207, 218, 219, 222, 227, 246; C.I.Acid Blue 1、7、9、15、22、23、25、27、29、40、41、43、45、49、54、59、60、62、72、74、76、78、80、82、83、87、90、92、93、100、102、103、104、106、112、113、114、117、120、126、127、127:1、128、129、130、131、133、138、140、142、143、151、154、156、158、161、166、167、168、170、171、175、181、182、183、184、185、187、192、193、201、203、204、205、207、209、220、221、224、225、229、230、232、239、247、249、258、260、264、271、277、277:1、278、279、280、284、288、290、296、298、300、317、324、326、333、335、338、342、350; C.I.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、234; C.I.Acid Orange 1、7、8、10、19、20、24、28、33、41、43、45、51、56、63、64、65、67、74、80、82、85、86、87、88、94、95、122、123、124; C.I.Acid Green 3、7、9、12、16、19、20、25、27、28、35、36、40、41、43、44、48、56、57、60、61、65、73、75、76、78、79; CIAcid Brown 2, 4, 13, 14, 19, 20, 27, 28, 30, 31, 39, 44, 45, 46, 48, 53, 100, 101, 103, 104, 106, 160, 16 1, 165, 188, 224, 225, 226, 231, 232, 236, 247, 256, 257, 266, 268, 276, 277, 282, 289, 29 Examples include 4, 295, 296, 297, 298, 299, 300, 301, and 302.

[0022] Examples of direct dyes include CI Direct Red 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81, 83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 212, 214, 218, 221, 223, 224, 225, 226, 227, 232, 233, 240, 241, 242, 243, and 247; CIDirect Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100, 101; CIDirect Yellow 8, 9, 11, 12, 27, 28, 29, 33, 35, 39, 41, 44, 50, 53, 58, 59, 68, 86, 87, 93, 95, 96, 98, 100, 106, 108, 109, 110, 130, 132, 142, 144, 161, 163; CI Direct Blue 1, 10, 15, 22, 25, 41, 55, 67, 68, 71, 76, 77, 78, 80, 84, 86, 87, 90, 98, 106, 108, 109, 120, 151, 156, 158, 159, 160, 153, 168, 189, 192, 19 3, 194, 199, 200, 201, 202, 203, 207, 211, 213, 214, 218, 225, 226, 229, 236, 237, 244, 248, 249, 251, 252, 264, 270, 280, 288, 289, 291; Examples of CIDirect Black models include 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, etc.

[0023] Examples of reactive dyes include CIReactive Yellow 1, 2, 3, 5, 11, 13, 14, 15, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 29, 35, 37, 40, 41, 42, 47, 51, 55, 65, 67, 81, 95, 116, 142, 161; CIReactive Red 1, 3, 3:1, 4, 13, 14, 17, 19, 21, 22, 23, 24, 24:1, 25, 26, 29, 31, 32, 35, 37, 40, 41, 43, 44, 45, 46, 49, 55, 60, 66, 74, 79, 96, 97, 108, 141, 180, 218, 226, 245; CIReactive Violet 1, 3, 4, 5, 6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27, 33, 34; CIReactive Blue 1, 2, 3, 5, 7, 8, 10, 13, 14, 15, 17, 18, 19, 21, 23, 25, 26, 27, 28, 29, 32, 35, 38, 41, 49, 63, 72, 75, 80, 95, 190; CIReactive Orange 1, 2, 4, 5, 7, 12, 13, 14, 16, 20, 29, 33, 35, 38, 64, 67, 71, 72, 72:1, 78, 82, 84, 86, 87, 91, 99, 99:1, 107, 113, 122, 124, 125; Examples include CIReactive Black 1, 3, 4, 5, 7, 8, 11, 12, 14, 17, 21, 23, 26, 31, 32, 34, and 39.

[0024] Examples of disperse dyes include CIDisperse Red 60, 82, 86, 86:1, 92, 152, 154, 167:1, 191, and 279; CIDisperse Yellow 64, 71, 86, 114, 153, 163, 233, 245; CIDisperse Blue 27, 60, 73, 77, 77:1, 87, 1 65, 165:1, 257, 367; CIDisperse Violet 26, 33, 36, 57; Examples include CIDisperse Orange 30, 41, 61, and 80.

[0025] When using disperse dyes, the surface of the disperse dye may be modified by oxidation or sulfonation with ozone, hypochlorous acid, fuming sulfuric acid, etc., for example, to improve dispersion stability in the inkjet ink composition, similar to the pigments described later. Furthermore, the dispersibility of the disperse dye may be improved by using a dispersant. Dispersants will be described later.

[0026] For example, inorganic pigments and organic pigments can be used as pigments.

[0027] Inorganic pigments are not particularly limited, but examples 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); and white pigments such as iron oxide, titanium oxide, zinc oxide, and silica.

[0028] Examples of carbon black include Mitsubishi Chemical Corporation's No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No. 2200B. Examples of Degussa's Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Pritex 35, U, V, 140U, and Special Black 6, 5, 4A, 4, and 250. Examples of Columbia Carbon's Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, and 700. Examples include Cabot's Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, and Elftex 12.

[0029] Examples of white pigments include CI Pigment White 1, which is basic lead carbonate; CI Pigment White 4, which is zinc oxide; CI Pigment White 5, which is a mixture of zinc sulfide and barium sulfate; CI Pigment White 6, which is titanium dioxide; CI Pigment White 6:1, which is titanium dioxide containing other metal oxides; CI Pigment White 7, which is zinc sulfide; CI Pigment White 18, which is calcium carbonate; CI Pigment White 19, which is clay; CI Pigment White 20, which is titanium mica; CI Pigment White 21, which is barium sulfate; CI Pigment White 22, which is gypsum; CI Pigment White 26, which is magnesium oxide and silicon dioxide; CI Pigment White 27, which is silicon dioxide; and CI Pigment White 28, which is anhydrous calcium silicate. Among these, it is preferable to use CI Pigment White 6, which has excellent color development and opacity.

[0030] Examples of organic pigments include quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ancenthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimimidazolone pigments, isoindolinone pigments, azomethine pigments, or azo pigments.

[0031] Specific examples of organic pigments 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 Bat Blue 4, 60, etc. Preferably, one or more mixtures 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. Preferably, one or more mixtures selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19 can be exemplified.

[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, 185, etc. Preferably, one or more mixtures selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, 138, 150, and 180 can be exemplified.

[0035] Other colored pigments can also be used. For example, orange pigment and green pigment can be used.

[0036] When using pigments, for example, to improve dispersion stability in the inkjet ink composition, the surface of the pigment may be modified by oxidation or sulfonation with ozone, hypochlorous acid, fuming sulfuric acid, etc., or the dispersibility of the pigment may be improved by using a dispersant. Examples of dispersants include (meth)acrylic resins and their salts, such as poly(meth)acrylic acid, (meth)acrylic acid-acrylonitrile copolymer, (meth)acrylic acid-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid copolymer, vinylnaphthalene-(meth)acrylic acid copolymer; styrene resins and their salts, such as styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, styrene-α-methylstyrene-(meth)acrylic acid copolymer, styrene-α-methylstyrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, etc.; and polymer compounds containing urethane bonds formed by the reaction of isocyanate groups and hydroxyl groups. These include urethane resins and their salts, which may be linear or branched and may or may not have a cross-linked structure; polyvinyl alcohols; vinylnaphthalene-maleic acid copolymers and their salts; vinyl acetate-maleic acid ester copolymers and their salts; and water-soluble resins such as vinyl acetate-crotonic acid copolymers and their salts.

[0037] Examples of commercially available dispersants for styrene-acrylic resins include X-200, X-1, X-205, X-220, X-228 (manufactured by Seikoh PMC), Nopcospers® 6100, 6110 (manufactured by Sunnopco), Joncryl 67, 586, 611, 678, 680, 682, 819 (manufactured by BASF), DISPERBYK-190 (manufactured by Bic Chemie Japan), N-EA137, N-EA157, N-EA167, N-EA177, N-EA197D, N-EA207D, and E-EN10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0038] Examples of commercially available acrylic resin dispersants include BYK-187, BYK-190, BYK-191, BYK-194N, BYK-199 (manufactured by Big Chemie Co.), Aron A-210, A6114, AS-1100, AS-1800, A-30SL, A-7250, Examples include the CL-2 (manufactured by Toagosei Co., Ltd.).

[0039] Examples of commercially available urethane resin dispersants include BYK-182, BYK-183, BYK-184, BYK-185 (manufactured by Bic Chemi), TEGO Disperse710 (manufactured by Evonic Tego Chemi), and Borchi® Gen1350 (manufactured by OMG Borschers).

[0040] The dispersant may be used alone or in combination of two or more types. The dispersant content is preferably 5% to 50% by mass, more preferably 10% to 40% by mass, even more preferably 15% to 35% by mass, and particularly preferably 20% to 30% by mass, based on 100% by mass of pigment. A dispersant content of 5% by mass or more based on 100% by mass of pigment tends to ensure the dispersion stability of the pigment. Furthermore, a dispersant content of 50% by mass or less based on 100% by mass of pigment tends to keep the viscosity of the inkjet ink composition low.

[0041] The lower limit of the colorant content is not particularly limited, but is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 7.0% by mass or more, and particularly preferably 10.0% by mass or more, relative to the total amount of the inkjet ink composition. The upper limit of the colorant content is not particularly limited, but is preferably 30.0% by mass or less, more preferably 25.0% by mass or less, even more preferably 20.0% by mass or less, even more preferably 15.0% by mass or less, and particularly preferably 12.0% by mass or less, relative to the total amount of the inkjet ink composition.

[0042] It is also preferable to set the content of the water-soluble dye within the above-mentioned range. In particular, it is preferable that the content of the water-soluble dye be 5.0% by mass or more and 20.0% by mass or less, relative to the total amount of the inkjet ink composition, and more preferably 10.0% by mass or more and 20.0% by mass or less. If the content of the water-soluble dye is within the above range, precipitation and solidification of the colorant are likely to occur, which tends to result in poor clogging recovery performance. However, according to the inkjet ink composition of this embodiment, good clogging recovery performance tends to be obtained even within such a content range.

[0043] 1.2 Organic Solvents The inkjet ink composition according to this embodiment contains an organic solvent, which contains triethylene glycol monobutyl ether (BTG), tetraethylene glycol monobutyl ether (BTeG), and one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam (hereinafter also referred to as "specific amides"). Although the properties of an organic solvent generally refer to a liquid, even a solid substance (at 20°C and 1 atm) is treated as an organic solvent in this specification as long as it has the property of dissolving other organic solvents and dissolving substances.

[0044] 1.2.1 BTG The organic solvent contains triethylene glycol monobutyl ether (BTG).

[0045] The content of triethylene glycol monobutyl ether (BTG) is not particularly limited, but is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 2.0% by mass or more, particularly preferably 3.0% by mass or more, and most particularly preferably 4.0% by mass or more, relative to the total amount of the inkjet ink composition. Furthermore, while the content of triethylene glycol monobutyl ether (BTG) is not particularly limited, it is preferably 30.0% by mass or less, more preferably 25.0% by mass or less, even more preferably 20.0% by mass or less, even more preferably 15.0% by mass or less, and most preferably 10% by mass or less, relative to the total amount of the inkjet ink composition. A concentration of 0% by mass or less is particularly preferred, and 8.0% by mass or less is even more preferred. In particular, the content of triethylene glycol monobutyl ether (BTG) is preferably 1.0% by mass or more and 20.0% by mass or less relative to the total amount of the inkjet ink composition. When the BTG content is within the above range, it tends to provide a better balance between improved solubility and dispersibility of the colorant and viscosity increase, resulting in a better balance of clogging recovery and continuous ejection stability.

[0046] Furthermore, according to the inkjet ink composition of this embodiment, even when the BTG content is relatively high, it is possible to reduce the viscosity increase due to BTG while improving the solubility and dispersibility of the colorant, thus tending to provide excellent clogging recovery and excellent continuous ejection stability. When the BTG content is relatively high, for example, the BTG content is preferably 5.0% by mass or more, more preferably 8.0% by mass or more, even more preferably 10.0% by mass or more, even more preferably 12.0% by mass or more, and particularly preferably 15.0% by mass or more, based on the total amount of the inkjet ink composition.

[0047] 1.2.2 BTeG The organic solvent contains tetraethylene glycol monobutyl ether (BTeG).

[0048] The content of tetraethylene glycol monobutyl ether (BTeG) is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.10% by mass or more, particularly preferably 0.20% by mass or more, and most particularly preferably 0.40% by mass or more, relative to the total amount of the inkjet ink composition. Furthermore, the content of tetraethylene glycol monobutyl ether (BTeG) is not particularly limited, but is preferably 15.0% by mass or less, more preferably 10.0% by mass or less, even more preferably 5.0% by mass or less, even more preferably 3.0% by mass or less, particularly preferably 1.5% by mass or less, and most particularly preferably 1.0% by mass or less, relative to the total amount of the inkjet ink composition. Even with a relatively low BTeG content, as within the above range, it tends to be possible to reduce the viscosity increase due to BTg while improving the solubility and dispersibility of the colorant, and to produce a product with excellent clogging recovery and continuous dispensing stability.

[0049] The mass ratio of tetraethylene glycol monobutyl ether content to triethylene glycol monobutyl ether content (BTeG / BTG) is preferably 3% or more, more preferably 5% or more, even more preferably 7% or more, and particularly preferably 9% or more. Furthermore, the mass ratio (BTeG / BTG) is preferably 50% or less, more preferably 20% or less, even more preferably 15% or less, and particularly preferably 13% or less. In particular, it is preferable that the mass ratio of tetraethylene glycol monobutyl ether content to triethylene glycol monobutyl ether content (BTeG / BTG) is 5% or more and 15% or less. When this mass ratio (BTeG / BTG) is within the above range, it tends to further reduce the viscosity increase due to BTG, while further improving the solubility and dispersibility of the colorant, and resulting in superior clogging recovery and continuous discharge stability.

[0050] 1.2.3 Specific Amides The organic solvent contains one or more substances (specific amides) selected from N-hydroxyethyl-2-pyrrolidone (HEP) and ε-caprolactam (εCPL).

[0051] The content of one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam is not particularly limited, but is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, relative to the total amount of the inkjet ink composition. In contrast, a concentration of 20.0% by mass or less is preferred, 15.0% by mass or less is more preferred, 12.0% by mass or less is even more preferred, 10.0% by mass or less is even more preferred, and 8.0% by mass or less is particularly preferred. In particular, it is preferable that the content of one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam is 5.0% by mass or more and 15.0% by mass or less relative to the total amount of the inkjet ink composition. When the specific nitrogen-containing solvent is within the above range, the balance between hydrophilicity and hydrophobicity in the ink components tends to be better, and the continuous ejection stability tends to be further improved.

[0052] The mass ratio ((BTG+BTeG) / (HEP+εCPL)) of the total content of triethylene glycol monobutyl ether and tetraethylene glycol monobutyl ether (BTG+BTeG) to the content of one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam (HEP+εCPL) is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 50% or more. Furthermore, the mass ratio ((BTG+BTeG) / (HEP+εCPL)) is preferably 300% or less, more preferably 250% or less, even more preferably 200% or less, particularly preferably 150% or less, and most particularly preferably 100% or less. Being within the above range tends to result in excellent clogging recovery and continuous discharge stability.

[0053] 1.2.4 Other Organic Solvents The organic solvent may contain organic solvents other than those listed above. Examples of other organic solvents include esters, glycol ethers, cyclic esters, amides, alcohols, polyhydric alcohols, and the like.

[0054] 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, methoxybutyl acetate, ethylene glycol diacetate, and diethylene glycol. Examples of glycol diesters include propyl 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.

[0055] Examples of glycol ethers include monoethers or diethers of alkylene glycols. Examples of alkylene glycol monoethers 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, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene Examples include alkylene glycol monoalkyl ethers such as dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monobutyl ether. Examples of alkylene glycol diethers include 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.

[0056] 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 atoms of the methylene group adjacent to the carbonyl group are substituted with alkyl groups having 1 to 4 carbon atoms.

[0057] Examples of amides include cyclic amides (lactams) such as 2-pyrrolidone, 2-piperidone, N-methyl-ε-caprolactam, N-cyclohexyl-2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, N-butylpyrrolidone, 5-methyl-2-pyrrolidone, β-propiolactam, ω-heptalactam, N,N-dimethylacetacetamide, N,N-diethylacetacetamide, N-methylacetacetamide, N,N -Dimethylisobutyrate, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylpropionamide, 3-methoxy-N,N-dimethylpropanamide (DMPA), 3-n-butoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy Xy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide Examples of chain-like amides include propionamide, 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, and 3-tert-butoxy-N,N-methylethylpropionamide.

[0058] Examples of alcohols include compounds in which one hydrogen atom of an alkane is replaced by a hydroxyl group. The alkane is preferably one with 10 or fewer carbon atoms, more preferably one with 6 or fewer carbon atoms, and even more preferably one with 3 or fewer carbon atoms. (Alkane carbon number) The ratio is 1 or more, and preferably 2 or more. The alkane may be linear or branched. Examples of alcohols include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol, 2-phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0059] Polyhydric alcohols are molecules that contain two or more hydroxyl groups. Polyhydric alcohols can be further classified into, for example, alkanediols and polyols.

[0060] Alkanediols include, for example, compounds in which an alkane is substituted with two hydroxyl groups. Examples of alkanediols include 1,2-alkanediols, which are a general term for compounds in which hydroxyl groups are substituted at the 1st and 2nd positions of an alkane, and other alkanediols other than 1,2-alkanediols. Alkanediols are preferably diols of alkanes having 5 or more carbon atoms. The number of carbon atoms in the alkane is preferably 5 to 15, more preferably 6 to 10, and even more preferably 6 to 8. Preferably, it is a 1,2-alkanediol.

[0061] Examples of 1,2-alkanediols include ethylene glycol, 1,2-propanediol (propylene glycol), 1,2-butanediol, 1,2-pentanediol (1,2PD), 1,2-hexanediol, 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, and 3 Examples include -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, and 3-ethyl-4-methyl-1,2-hexanediol.

[0062] Other examples of alkanediols include 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.

[0063] Examples of polyols include condensates formed by the intermolecular condensation of two or more alkanediol molecules via hydroxyl groups, and compounds having three or more hydroxyl groups. The polyols are preferably polyols of alkanes having 4 or fewer carbon atoms, or intermolecular condensates of hydroxyl groups of polyols of alkanes having 4 or fewer carbon atoms. The number of carbon atoms in the alkane is preferably 2 to 3. The number of hydroxyl groups in the polyol molecule is 2 or more, preferably 5 or less, and more preferably 3 or less. If the polyols are the above intermolecular condensates, the number of intermolecular condensations is 2 or more, preferably 4 or less, and more preferably 3 or less.

[0064] As an example of a condensate formed when two or more molecules of alkanediols undergo intermolecular condensation of their hydroxyl groups, Examples include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0065] Compounds having three or more hydroxyl groups are compounds with an alkane or polyether structure as their backbone and containing three or more hydroxyl groups. Examples of compounds having three or more hydroxyl groups include glycerin, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylenetriol.

[0066] Other organic solvents may be used individually or in combination of two or more.

[0067] Among these other organic solvents, it is preferable to include polyhydric alcohols, more preferably to include one or more selected from alkanediols and polyols, and even more preferably to include alkanediols.

[0068] The content of other organic solvents is not particularly limited, but is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, relative to the total amount of the inkjet ink composition. Furthermore, the content of other organic solvents is not particularly limited, but is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 12.0% by mass or less, relative to the total amount of the inkjet ink composition.

[0069] The total content of organic solvents is not particularly limited, but is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, and even more preferably 15.0% by mass or more, relative to the total amount of the inkjet ink composition. Furthermore, although the total content of organic solvents is not particularly limited, is preferably 50.0% by mass or less, more preferably 40.0% by mass or less, and even more preferably 30.0% by mass or less, relative to the total amount of the inkjet ink composition.

[0070] 1.3 Water The inkjet ink composition according to this embodiment contains water.

[0071] Examples of suitable water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water, which has reduced ionic impurities. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can suppress the growth of bacteria and fungi when the maintenance fluid is stored for a long period of time.

[0072] The water content is preferably 50% by mass or more, more preferably 50 to 99% by mass, in the liquid medium component. Furthermore, it is preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and even more preferably 65 to 80% by mass. The liquid medium refers to a solvent component such as water or an organic solvent. Furthermore, the water content is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more, relative to the total amount of the inkjet ink composition. There is no particular upper limit to the water content, but for example, it is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less, relative to the total amount of the inkjet ink composition.

[0073] 1.4 Fixing resin The inkjet ink composition according to this embodiment may contain a fixing resin. The fixing resin has functions such as improving the adhesion and abrasion resistance of the ink components, and smoothing the surface of the recording medium or the ink coating.

[0074] The fixing resin may be a water-soluble resin, but it is preferably in the form of resin particles. The resin particles are often handled in emulsion form, but they may also be in powder form. The fixing resin can be dispersed or dissolved in the solvent component of the ink and included in the ink.

[0075] Examples of fixing resins include urethane resins, acrylic resins (including styrene-acrylic resins), fluorene resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, and ethylene vinyl acetate resins. Among these, urethane resins, acrylic resins, polyolefin resins, and polyester resins are preferred.

[0076] Urethane resins are a general term for resins that contain urethane bonds. In addition to urethane bonds, urethane resins may also use polyether-type urethane resins containing ether bonds in the main chain, polyester-type urethane resins containing ester bonds in the main chain, polycarbonate-type urethane resins containing carbonate bonds in the main chain, etc. Furthermore, commercially available urethane resins may be used, such as Superflex 460, 460s, 840, E-4000 (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, D-6455 (product name, manufactured by Dainichi Seika Kogyo Co., Ltd.), Takelac WS-6021, WS-5100, W-512-A-6 (product name, manufactured by Mitsui Chemicals, Inc.), SunCure 2710 (product name, manufactured by Lubrizol), Permarin UA-150 (product name, manufactured by Sanyo Chemical Industries, Ltd.).

[0077] Acrylic resins are a general term for polymers obtained by polymerizing at least one acrylic monomer, such as (meth)acrylic acid or (meth)acrylic acid ester. Examples include resins obtained from acrylic monomers and copolymers of acrylic monomers with other monomers. For example, acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers, are examples. Examples of vinyl monomers include styrene.

[0078] Acrylic monomers such as acrylamide and acrylonitrile can also be used. For resin emulsions made from acrylic resins, commercially available products may be used, for example, selected from FK-854, Movinyl 6969D, 6899D, 952B, 718A (trade names, manufactured by Japan Coating Resin Co., Ltd.), Nipol LX852, LX874 (trade names, manufactured by Nippon Zeon Co., Ltd.).

[0079] In this specification, the acrylic resin may be a styrene-acrylic resin as described later.

[0080] Styrene-acrylic resins are copolymers obtained from styrene monomers and (meth)acrylic monomers, and examples include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers. For the styrene-acrylic resin, commercially available products may be used, such as Joncryl 62J, 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (product names, manufactured by BASF), Movinyl 966A, 975N (product names, manufactured by Japan Coating Resin Co.), Vinibran 2586 (manufactured by Nisshin Chemical Industry Co.), etc.

[0081] Polyolefin resins have olefins such as ethylene, propylene, and butylene as their structural framework, and known types can be appropriately selected and used. Commercially available olefin resins can be used, for example, Arrowbase CB-1200, CD-1200 (trade names, manufactured by Unitika Ltd.).

[0082] Furthermore, the fixing resin may be supplied in the form of an emulsion. Examples of commercially available resin emulsions include Microgel E-1002, E-5002 (product names of Nippon Paint Co., Ltd., styrene-acrylic resin emulsion), Boncoat 4001 (product name of DIC Corporation, acrylic resin emulsion), Boncoat 5454 (product name of DIC Corporation, styrene-acrylic resin emulsion), Polysol AM-710, AM-920, AM-2300, AP-4735, AT-860, PSASE-4210E (acrylic resin emulsion), Polyzol AP-7020 (styrene-acrylic resin emulsion), Polyzol SH-502 (vinyl acetate resin emulsion), Polyzol AD-13, AD-2, AD-10, AD-96, AD-17, AD-70 (ethylene-vinyl acetate resin emulsion), Polyzol PSASE-6010 (ethylene-vinyl acetate resin emulsion) (product name manufactured by Showa Denko), Polyzol SAE1014 (product name, styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Saibinol SK-200 (product name, acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.) (Manufactured by [Company Name]), AE-120A (JSR Corporation product name, acrylic resin emulsion), AE373D (E-Tech Corporation product name, carboxy-modified styrene-acrylic resin emulsion), Seikadine 1900W (Dainichi Seika Kogyo Co., Ltd. product name, ethylene-vinyl acetate resin emulsion), Vinibran 2682 (acrylic resin emulsion), Vinibran 2886 (vinyl acetate-acrylic resin emulsion), Vinibran 5202 (acrylic acetate resin emulsion) (Nisshin Chemical Industry Co., Ltd. product name), Elitel KA-5071S, KT-8803, KT-9204, KT -8701, KT-8904, KT-0507 (Unitika Corporation product names, polyester resin emulsion), Hi-Tec SN-2002 (Toho Chemical Co., Ltd. product name, polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (Mitsui Chemicals, Inc. product names, urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 700 (Daiichi Kogyo Seiyaku Co., Ltd. product names, urethane resin emulsion), Permarin UA-150 (Sanyo Chemical Industries, Ltd.,Urethane resin emulsion), SunCure 2710 (manufactured by Lubrizol Japan, urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (manufactured by Kusumoto Chemical Co., Ltd., urethane resin emulsion), Adekabon Titer HUX-380, 290K (manufactured by ADEKA Corporation, urethane resin emulsion), Movinyl 966A, Movinyl 7320 (manufactured by Japan Coating Resin Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX -7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (all manufactured by BASF), NK Binder R-5HN (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane: manufactured by DIC Corporation), Joncryl 7610 (manufactured by BASF), etc. may be selected and used.

[0083] From the viewpoint of achieving superior abrasion resistance, the content of the fixing resin is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 2.0% by mass or more, and particularly preferably 3.0% by mass or more, relative to the total amount of the inkjet ink composition. Furthermore, from the viewpoint of achieving superior ejection stability, the content of the fixing resin is preferably 15.0% by mass or less, more preferably 10% by mass or less, even more preferably 8.0% by mass or less, and even more preferably 5.0% by mass or less, relative to the total amount of the inkjet ink composition.

[0084] 1.5 Surfactants The inkjet ink composition according to this embodiment may contain a surfactant. Any of the following surfactants can be used: nonionic surfactants, anionic surfactants, cationic surfactants, or amphoteric surfactants, and these may be used in combination. Among surfactants, acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants are more preferably used, and acetylene glycol-based surfactants are even more preferably used.

[0085] The acetylene glycol-based surfactant is not particularly limited, but for example, one or more selected from 2,4,7,9-tetramethyl-5-decine-4,7-diol and alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decine-4,7-diol, and 2,4-dimethyl-5-decine-4-ol and alkylene oxide adducts of 2,4-dimethyl-5-decine-4-ol are preferred. Commercially available acetylene glycol-based surfactants include, but are not limited to, Surfinol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, and DF110D (all are brand names, manufactured by Air Products Japan Co., Ltd.). Examples include Olphine B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP.4001, EXP.4036, EXP.4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all brand names, manufactured by Nisshin Chemical Industry Co., Ltd.), and Acetylene Nol E00, E00P, E40, E100 (all brand names, manufactured by Kawaken Fine Chemical Co., Ltd.). Acetylene glycol-based surfactants may be used individually or in combination of two or more types.

[0086] Examples of silicone-based surfactants are not particularly limited, but include polysiloxane compounds and polyether-modified organosiloxanes. Examples of commercially available silicone-based surfactants are not particularly limited, but include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-349 (all trade names, manufactured by BI-Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, and KF-355. Examples include A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017 (all product names, manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG503A, Silface SAG014 (all product names, manufactured by Nisshin Chemical Industry Co., Ltd.). Silicone-based surfactants may be used individually or in combination of two or more types.

[0087] Examples of fluorinated surfactants include, but are not limited to, perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphate esters, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkylamine oxide compounds. Examples of commercially available fluorinated surfactants include, but are not limited to, S-144, S-145 (trade names, manufactured by Asahi Glass Co., Ltd.); FC-170C, FC-430, Florard-FC4430 (trade names, manufactured by Sumitomo 3M Limited); FSO, FSO-100, FSN, FSN-100, FS-300 (trade names, manufactured by Dupont); FT-250, 251 (trade names, manufactured by Neos Co., Ltd.). Fluorinated surfactants may be used individually or in combination of two or more types.

[0088] The above surfactants may be used individually or in combination of two or more. For example, Among the surfactants, those that function as defoaming agents may also be used. An example of such a defoaming agent is Surfinol DF110D (trade name, manufactured by Air Products Japan Co., Ltd.).

[0089] The surfactant content is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.0% by mass or less, and most particularly preferably 0.5% by mass or less, relative to the total amount of the inkjet ink composition. The lower limit of the surfactant content is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and most preferably 0.15% by mass or more, relative to the total amount of the inkjet ink composition.

[0090] 1.6 pH adjuster The inkjet ink composition according to this embodiment may contain a pH adjuster.

[0091] pH adjusters are not particularly limited, but 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, trippropanolamine, triisopropanolamine, diisopropanolamine, and trishydroxymethylaminomethane (THAM); and organic acids such as adipic acid, citric acid, succinic acid, lactic acid, and N,N-bis(2-hydroxymethylaminomethane). Good's buffers such as thioethyl)-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-acetamide)-2-aminoethanesulfonic acid (ACES), cholamine hydrochloride, N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), acetamidoglycine, tricine, glycinamide, bicine, etc., as well as phosphate buffers, citrate buffers, Tris buffers, etc., may be used. Among these, inorganic bases are preferred, and potassium hydroxide is more preferred.

[0092] The above pH adjusting agents may be used individually or in combination of two or more.

[0093] The total content of pH adjusters is preferably 5.00% by mass or less, more preferably 3.00% by mass or less, even more preferably 1.00% by mass or less, particularly preferably 0.70% by mass or less, and most particularly preferably 0.50% by mass or less, relative to the total amount of the inkjet ink composition. The lower limit of the total content of pH adjusters is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and still more preferably 0.15% by mass or more, relative to the total amount of the inkjet ink composition.

[0094] 1.7 Other ingredients The inkjet ink composition according to this embodiment may further contain various additives as needed, such as ureas, chelating agents, preservatives / antifungal agents, amines, sugars, rust inhibitors, viscosity modifiers, antioxidants, and fungicides.

[0095] Examples of ureas include urea, ethylene urea, tetramethylurea, thiourea, 1,3-dimethyl-2-imidazolidinone, and betaines (trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine, N,N,N-trimethylalanine, N,N,N-triethylalanine, N,N,N-triisopropylalanine). Examples include N,N,N-trimethylmethylalanine, carnitine, acetylcarnitine, etc.

[0096] When ureas are included, there are no particular limitations, but the amount is preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass, even more preferably 1 to 5% by mass, and particularly preferably 2 to 4% by mass, based on the total amount of the inkjet ink composition.

[0097] Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA) and its salts (e.g., disodium dihydrogen ethylenediaminetetraacetic acid), 3-hydroxy-2,2'-iminodisuccinic acid (HIDS) and its salts (tetrasodium 3-hydroxy-2,2'-iminodisuccinic acid), and iminodisuccinic acid (IDS) and its salts (tetrasodium iminodisuccinic acid).

[0098] When a chelating agent is included, it is not particularly limited, but is preferably 0.001 to 1.000% by mass, more preferably 0.005 to 0.100% by mass, even more preferably 0.010 to 0.050% by mass, and particularly preferably 0.010 to 0.030% by mass, relative to the total amount of the inkjet ink composition.

[0099] Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-benzisothiazolin-3-one, and octyldiethanolamine. Commercial preservatives and fungicides may also be used, such as Proxel XL-2, Proxel GXL (trade names, products of Abysia, containing 1,2-dibenzoisothiazolin-3-one), Denicide CSA, and NS-500W (trade names, products of Nagase ChemteX Corporation).

[0100] When preservatives and antifungal agents are included, the amount is not particularly limited, but is preferably 0.01 to 5.00% by mass, more preferably 0.05 to 3.00% by mass, even more preferably 0.10 to 1.00% by mass, and particularly preferably 0.10 to 0.50% by mass, relative to the total amount of the inkjet ink composition.

[0101] 1.8 Manufacturing and physical properties of inkjet ink compositions The inkjet ink composition according to this embodiment can be obtained by mixing the above-mentioned components in any order and removing impurities by filtration or other means as necessary. A preferred mixing method involves sequentially adding the materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirring them together. For filtration, centrifugal filtration or filter filtration can be performed as needed.

[0102] From the viewpoint of reliability as an inkjet ink, the inkjet ink composition according to this embodiment preferably has a surface tension of 20 mN / m to 40 mN / m at 20°C, and more preferably 22 mN / m to 35 mN / m. Similarly, from the same viewpoint, the viscosity of the ink at 20°C is preferably 1.5 mPa·s to 10 mPa·s, and more preferably 2 mPa·s to 8 mPa·s. One method for bringing the surface tension and viscosity within the above range is to adjust the type of organic solvent and surfactant mentioned above, and the amount of these and water added.

[0103] 2. Inkjet recording method An inkjet recording method according to one embodiment of the present invention includes the step of ejecting the above-mentioned inkjet ink composition from an inkjet head and adhering it to a recording medium.

[0104] According to the inkjet recording method of this embodiment, by using the above-mentioned inkjet ink composition, it is possible to achieve excellent clogging recovery and excellent continuous ejection stability.

[0105] 2.1 Ink application process The inkjet recording method according to this embodiment includes a step of ejecting the above-described inkjet ink composition from an inkjet head and adhering it to a recording medium (ink adhesion step).

[0106] The ink adhesion process can be carried out using an inkjet recording device as described later. Specifically, the inkjet ink composition can be filled into an inkjet head so that it can be ejected from a predetermined nozzle, and then ejected onto the recording medium at a predetermined timing, thereby adhering the inkjet ink composition to the recording medium.

[0107] The recording medium is not particularly limited and may have a recording surface that absorbs liquid or may not have a recording surface that absorbs liquid. Therefore, there are no particular restrictions on the recording medium, and for example, paper, film, fabric, metal, glass, polymer, etc. can be used. Furthermore, transfer paper used for sublimation transfer onto the recording medium can also be used as the recording medium in the inkjet recording method.

[0108] The fabric is not particularly limited. The materials that make up the fabric are not particularly limited and include, for example, natural fibers such as cotton, linen, wool, and silk; synthetic fibers such as polypropylene, polyester, acetate, triacetate, polyamide, and polyurethane; and biodegradable fibers such as polylactic acid. Blends of these fibers are also acceptable. The fabric may be made from the above-mentioned fibers in any form, such as woven, knitted, or nonwoven fabric, or it may be a blended fabric.

[0109] 2.2 Pretreatment liquid application process The inkjet recording method according to this embodiment may include a step of applying a pretreatment solution to the recording medium before the ink application step. This may further improve the color development of the ink.

[0110] Methods for applying the pretreatment solution to the recording medium include non-contact and contact methods, or a combination thereof, such as inkjet printing, coating with rollers or bars, applying the pretreatment solution to the recording medium using various sprays, immersing the recording medium in the pretreatment solution, and applying the pretreatment solution to the recording medium with a brush or the like.

[0111] The components contained in the pretreatment solution are not particularly limited, but examples include ammonium salts, thickeners, water, and urea. The components contained in the pretreatment solution are described below.

[0112] The pretreatment solution may contain an ammonium salt. The ammonium salt is not particularly limited, but it is preferably one or more selected from the group consisting of ammonium formate, ammonium acetate, ammonium chloride, and ammonium nitrate.

[0113] The ammonium salt content is preferably 0.1 to 10% by mass, more preferably 1 to 8% by mass, and even more preferably 3 to 6% by mass, relative to the total amount of the pretreatment solution.

[0114] The pretreatment solution may contain a thickening agent. The thickening agent has functions such as increasing the initial viscosity or improving the rate of change in viscosity after drying.

[0115] The thickening agent is not particularly limited, but examples include natural gums such as guar gum and locust bean gum, starches, sodium alginate, seaweed such as funori, plant peels such as pectinic acid, cellulose derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose, and carboxymethylcellulose, modified starches such as roasted starch, alpha starch, carboxymethyl starch, carboxyethyl starch, and hydroxyethyl starch, modified natural gums such as silatsu gum and roasted bean gum, algin derivatives, or synthetic adhesives and emulsions such as polyvinylpyrrolidone, polyethylene oxide, polyvinyl alcohol, and polyacrylic acid esters. The thickening agent may be used alone or in combination of two or more types.

[0116] The amount of thickener is preferably 0.1 to 5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 1 to 3% by mass, relative to the total amount of the pretreatment solution.

[0117] The pretreatment solution may contain water. The amount and type of water are the same as those for the inkjet ink composition described above.

[0118] The pretreatment solution may contain urea. The type of urea is the same as that used in the inkjet ink composition described above. The urea content is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass, relative to the total amount of the pretreatment solution.

[0119] The pretreatment solution may contain, in addition to the above-mentioned components, organic solvents, surfactants, pH adjusters, various additives, etc., which can be contained in the inkjet ink composition described above.

[0120] 2.3 Drying process The inkjet recording method according to this embodiment may include a step of drying the recording medium (drying step). The drying step of the recording medium can be performed, for example, using a drying means described later when using an inkjet recording device. Furthermore, it can be performed by any suitable drying means, not limited to an inkjet recording device. This tends to dry the resulting image, suppressing image blurring and allowing for more efficient fixing.

[0121] 2.4 Other processes The inkjet recording method according to this embodiment may further include other steps as appropriate, such as a step of applying another composition, a cleaning step, and so on.

[0122] 2.5 Inkjet Recording Devices In the inkjet recording method according to this embodiment, the inkjet recording apparatus can be either serial or line type. These types of inkjet recording apparatuses are equipped with an inkjet head, and by changing the relative positional relationship between the recording medium and the inkjet head, droplets of inkjet ink composition are ejected from the nozzle holes of the inkjet head at a predetermined timing and in a predetermined volume (mass), thereby adhering the inkjet ink composition to the recording medium and forming a predetermined image.

[0123] The inkjet recording device can optionally employ known components such as a drying unit, a roll unit, and a winding device. Furthermore, the inkjet recording device may include a transport means for transporting the recording medium, an image layer forming means for recording an image using an inkjet ink composition, and a drying means for heating or blowing air onto the recording surface.

[0124] The conveying means can be configured, for example, by rollers. In that case, it may have multiple rollers. Alternatively, the recording medium can be attached to and held in place by a rubber belt or the like. Methods such as transporting by hand may be used. The position and number of transport means are arbitrary, as long as they can transport the recording medium. The transport means may include a roll mechanism, trays, and various platens.

[0125] The image layer forming means records an image layer by ejecting the above-mentioned inkjet ink composition onto the recording surface of the recording medium. The image layer forming means includes an inkjet head equipped with nozzles, and a nozzle row is assigned to each predetermined composition.

[0126] Drying means can be used to heat, dry, and / or remove volatile components from the recording medium of the image layer formed on the recording surface. Drying means may be provided at any position and in any number, taking into consideration the timing of the adhesion process and the transport path of the recording medium. Examples of drying means include methods of applying heat to the recording medium by platen heating, methods of blowing air onto the image on the recording medium, and methods combining these. Specifically, means used in these methods may include forced air heating, radiant heating, conductive heating, high-frequency drying, microwave drying, etc.

[0127] 3. Examples 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 refers to mass.

[0128] 3.1 Preparation of inkjet ink composition The inkjet ink compositions for Examples 1-16, 18-21, and Comparative Examples 1-4 were obtained by placing each component in a container to achieve the compositions shown in Table 1 (Figure 1) and Table 2 (Figure 2), mixing and stirring with a magnetic stirrer for 2 hours, and then filtering through a membrane filter with a pore size of 5 μm. Water was added so that the total amount of the composition was 100% by mass.

[0129] The inkjet ink composition for Example 17 was prepared by first mixing 40g of Pigment Red 122, 10g of Joncryl 611, 5g of triethanolamine, and 200g of water, and dispersing the mixture for 10 hours using a zirconia bead ball mill. The resulting dispersion was filtered through a membrane filter with a pore size of approximately 8 μm to remove coarse particles, and then diluted with water to a pigment concentration of 10% by mass to prepare a pigment dispersion. Next, the components of the materials listed in Table 2, excluding Pigiment Red 122, Joncryl 611, and triethanolamine water, were placed in a container, and 15% by mass of water was added and stirred and mixed. 40% by mass of the above pigment dispersion was added to this mixture, and then water was added to bring the total volume to 100% by mass. The mixture was stirred for 2 hours and filtered through a membrane filter with a pore size of approximately 5 μm to obtain the inkjet ink composition according to Example 17.

[0130] Further explanation is provided regarding the descriptions in Tables 1 and 2. [Dispersant] • Joncryl 611: Styrene-acrylic acid copolymer (manufactured by BASF Japan Ltd.) [Fixing resin] • Takelac WS-5100: Urethane resin emulsion (manufactured by Mitsui Chemicals, Inc.; the values ​​in the table represent the solid content.) [Organic solvents] BTG: Triethylene glycol monobutyl ether • BTeG: Tetraethylene glycol monobutyl ether HEP:N-hydroxyethyl-2-pyrrolidone [Surfactants] • Orphine E1010: Acetylene glycol-based surfactant (Nisshin Chemical Industry Co., Ltd.) (Manufactured) • Orphine P002W: Acetylene glycol-based surfactant (manufactured by Nisshin Chemical Industry Co., Ltd.) • Surfinol 104PG-50: Acetylene glycol-based surfactant (manufactured by Nisshin Chemical Industry Co., Ltd.) [Other ingredients] IDS: Iminodisuccinate • Proxel XL-2: 1,2-dibenzoisothiazolin-3-one type preservative (manufactured by Lonza Japan Co., Ltd.)

[0131] 3.2 Evaluation Test 3.2.1 Discharge recovery Each prepared inkjet ink composition was loaded into the Cyan row of an EW-M770T inkjet printer (manufactured by Seiko Epson Corporation). A cleaning operation was then performed, and the printer was forcibly stopped by unplugging the power cable when the inkjet head detached from the cap and moved to the printing area. After leaving the printer at room temperature for two weeks in this state, the power cable was plugged back in and the printer was turned on. The number of cleaning cycles required until the printer began ejecting ink normally was then counted. The results were evaluated according to the following criteria and are shown in Tables 1 and 2. (Evaluation Criteria) A: Recovery within 4 cleanings. B: Recovery within 7 cleanings C: Recovered within 10 cleaning cycles. D: No recovery even after 10 cleanings.

[0132] 3.2.2 Continuous Discharge Stability - (1) Each example of inkjet ink composition was loaded into a Monna Lisa Evo Tre 32-180 inkjet textile printing machine (manufactured by Seiko Epson Corporation), and pre-treated 100% silk fabric (twill, 50-60 g / m²) was used. 2A roll (140 cm wide) was set up, and continuous printing was performed in 600 x 600 D.PI 2-Pass mode. For the silk fabric pretreatment, a pretreatment solution prepared by mixing 1% by mass of sodium alginate, 1% by mass of guar gum, 4% by mass of ammonium sulfate, 10% by mass of urea, and 84% by mass of water was applied to the fabric, squeezed with a mangle at a pickup rate of 20%, and dried. Nozzle checks were performed every 100 m of silk fabric feed to confirm that printing was normal without any gaps or bends. The results were evaluated according to the following criteria and are recorded in Tables 1 and 2. (Evaluation Criteria) A: Printed successfully for over 1000m. B: Printed successfully for distances of 500m or more. C: Over 200m, printed successfully. D: The flight curve occurred by 200m.

[0133] 3.2.3 Continuous Discharge Stability - (2) Inkjet ink compositions were filled into any of the color columns (Cyan, Magenta, Yellow, Photo Black) of an EW-M770T inkjet printer (manufactured by Seiko Epson Corporation). FUJI XEROX printer paper "P" (A4 size) was loaded, and continuous printing was performed in plain paper / standard mode. Nozzle checks were performed every 1000 sheets to confirm that printing was normal without any missing or crooked lines. The results were evaluated according to the following criteria and are shown in Tables 1 and 2. (Evaluation Criteria) A: Over 5000 pages were printed successfully. B: Over 2500 pages printed successfully. C: Printed over 1000 pages successfully. D: Flight deviation occurred within 1000 frames.

[0134] 3.3 Evaluation Results The results are shown in Tables 1 and 2. As shown in Tables 1 and 2, the inkjet ink compositions containing a colorant, an organic solvent, and water, wherein the organic solvent is one or more selected from triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, N-hydroxyethyl-2-pyrrolidone, and ε-caprolactam, all exhibited excellent clogging recovery and continuous ejection stability.

[0135] In contrast, the inkjet ink compositions in each comparative example that did not satisfy the above configuration were inferior in at least one of the following: clogging recovery and continuous ejection stability.

[0136] The following conclusions can be drawn from the embodiments described above.

[0137] One embodiment of an inkjet ink composition is: An inkjet ink composition containing a colorant, an organic solvent, and water, The aforementioned organic solvent is triethylene glycol monobutyl ether, Tetraethylene glycol monobutyl ether and It contains one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam.

[0138] In one embodiment of the above inkjet ink composition, The content of the triethylene glycol monobutyl ether may be 1.0% by mass or more and 20.0% by mass or less based on the total amount of the inkjet ink composition.

[0139] In any embodiment of the above inkjet ink composition, The content of one or more substances selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam may be 5.0% by mass or more and 15.0% by mass or less based on the total amount of the inkjet ink composition.

[0140] In any embodiment of the above inkjet ink composition, The mass ratio of the tetraethylene glycol monobutyl ether content to the triethylene glycol monobutyl ether content may be 5% or more and 15% or less.

[0141] In any embodiment of the above inkjet ink composition, The aforementioned colorant may contain a water-soluble dye.

[0142] In any embodiment of the above inkjet ink composition, The water-soluble dye may be one or more selected from acid dyes, direct dyes, and reactive dyes.

[0143] In any embodiment of the above inkjet ink composition, The content of the water-soluble dye may be 5.0% by mass or more and 20.0% by mass or less based on the total amount of the inkjet ink composition.

[0144] One aspect of an inkjet recording method is: The process includes ejecting an inkjet ink composition according to any of the above embodiments from an inkjet head and adhering it to a recording medium.

[0145] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments, for example, configurations that have the same function, method and result, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments.

Claims

1. An inkjet ink composition containing a colorant, an organic solvent, and water, The aforementioned organic solvent is triethylene glycol monobutyl ether, Tetraethylene glycol monobutyl ether and An inkjet ink composition containing one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam.

2. The inkjet ink composition according to claim 1, wherein the content of the triethylene glycol monobutyl ether is 1.0% by mass or more and 20.0% by mass or less based on the total amount of the inkjet ink composition.

3. The inkjet ink composition according to claim 1, wherein the content of one or more selected from N-hydroxyethyl-2-pyrrolidone and ε-caprolactam is 5.0% by mass or more and 15.0% by mass or less based on the total amount of the inkjet ink composition.

4. The inkjet ink composition according to claim 1, wherein the mass ratio of the content of tetraethylene glycol monobutyl ether to the content of triethylene glycol monobutyl ether is 5% or more and 15% or less.

5. The inkjet ink composition according to claim 1, wherein the colorant comprises a water-soluble dye.

6. The inkjet ink composition according to claim 5, wherein the water-soluble dye is one or more selected from acid dyes, direct dyes, and reactive dyes.

7. The inkjet ink composition according to claim 5, wherein the content of the water-soluble dye is 5.0% by mass or more and 20.0% by mass or less with respect to the total amount of the inkjet ink composition.

8. An inkjet recording method comprising the step of ejecting an inkjet ink composition according to any one of claims 1 to 7 from an inkjet head and adhering it to a recording medium.

Images