Inkjet ink composition and recording method

Abstract

To provide an inkjet ink composition capable of obtaining excellent image quality and having excellent clogging recovery properties of an inkjet head.SOLUTION: There is provided an inkjet ink composition which is an aqueous inkjet ink composition used for recording on a recording medium which is a low-absorbent recording medium or a non-absorbent recording medium and contains a pigment, resin particles, a surfactant and a hardly water-soluble low-molecular-weight organic compound having a solubility in water of 10 g / 100 g of water or less which is any one of alkanediols or glycol ethers, wherein the surfactant includes a silicone-based surfactant and an acetylene glycol-based surfactant having an HLB value of 9 to 14 and the composition has a pH of 8 to 10.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink-jet ink composition and a recording method. [Background technology]

[0002] An inkjet recording method is known in which minute ink droplets are ejected from the nozzles of an inkjet head of an inkjet recording device to record an image on a recording medium, and its use in, for example, sign printing, label printing, packaging printing, etc. Among these methods, studies are being conducted on recording images on low-absorbency or non-absorbency recording media (hereinafter also referred to as "low / non-absorbency recording media") using ink containing at least water as a solvent (hereinafter also referred to as "water-based ink").

[0003] For example, Patent Document 1 describes a water-based ink containing a silicone surfactant and a poorly water-soluble organic compound such as a diol or glycol ether. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-154397 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the ink is still not sufficient in terms of obtaining excellent image quality and excellent recovery from clogging of the ink jet head. [Means for solving the problem]

[0006] One embodiment of the inkjet ink composition according to the present invention comprises: 1. A water-based inkjet ink composition comprising: It is used for recording on a recording medium that is a low-absorbency recording medium or a non-absorbency recording medium, The ink contains a pigment, resin particles, a surfactant, and a poorly water-soluble low-molecular-weight organic compound that is either an alkanediol or a glycol ether and has a solubility in water of 10 g / 100 g of water or less, The surfactant includes a silicone surfactant and an acetylene glycol surfactant having an HLB value of 9 to 14, The pH is 8 to 10.

[0007] One aspect of the recording method according to the present invention is to The method includes a step of ejecting the inkjet ink composition of the above embodiment from an inkjet head and depositing it on a recording medium that is a low-absorbency recording medium or a non-absorbency recording medium. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an example of an inkjet recording apparatus. [Figure 2] FIG. 1 is a schematic diagram of the periphery of a carriage in an example of an inkjet recording apparatus. [Figure 3] 1A and 1B are diagrams showing examples of inkjet ink compositions. [Figure 4] 1A and 1B are diagrams showing examples of inkjet ink compositions. [Figure 5] FIG. 10 is a diagram showing the evaluation results of each example and each comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes an embodiment of the present invention. The present invention is not limited to the following embodiments, and includes various modifications 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.

[0010] 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.

[0011] In this specification, the term "(meth)acrylic" means acrylic or methacrylic, and the term "(meth)acrylate" means acrylate or methacrylate.

[0012] 1. Inkjet ink composition An inkjet ink composition according to one embodiment of the present invention is a water-based inkjet ink composition for use in recording on a low-absorbency recording medium or a non-absorbency recording medium, and contains a pigment, resin particles, a surfactant, and a poorly water-soluble low-molecular-weight organic compound which is either an alkanediol or a glycol ether and has a solubility in water of 10 g / 100 g water or less, wherein the surfactants include a silicone-based surfactant and an acetylene glycol-based surfactant having an HLB value of 9 to 14, and the ink composition has a pH of 8 to 10.

[0013] When printing on low- or non-absorbent recording media using water-based inks, the inks do not wet or spread easily on the recording medium (they do not fill up well), so slight variations in the amount of ink droplets ejected from the nozzle or in the landing position can cause streaky irregularities in the printed image, making it difficult to obtain good image quality. In response to this, adding a poorly water-soluble low-molecular-weight organic compound to a water-based ink containing a silicone surfactant can improve the ink's wetting and spreading properties on low- or non-absorbent recording media, resulting in good image quality.

[0014] However, it has been found that when poorly water-soluble low-molecular-weight organic compounds are added to aqueous inks, the dispersion of pigments and resin particles becomes unstable, and the ability of inkjet heads to recover from clogging (hereinafter simply referred to as "clogging recovery") deteriorates. This is thought to be because poorly water-soluble low-molecular-weight organic compounds are highly hydrophobic, and when the water evaporates and dries near the nozzles of the inkjet head, the proportion of hydrophobic components in the ink increases relatively, destabilizing the dispersion of pigments and resin particles, which were stable when the proportion of hydrophilic components was high, and causing aggregation.

[0015] According to conventional knowledge, increasing the pH of the ink can sometimes improve clogging recovery. This is because making the ink pH more alkaline tends to stabilize the dispersion of pigment and resin particles, thereby reducing the occurrence of aggregation even when the water evaporates as the ink dries. However, in water-based inks containing silicone surfactants, if the alkalinity becomes too high, hydrolysis of the silicone surfactant is promoted, and over time the hydrophilic / hydrophobic balance of all the components in the ink is disrupted, destabilizing the dispersion of the pigment and resin particles and worsening clogging recovery. On the other hand, if the pH of the ink is not made more alkaline, the dispersion of the pigment and resin particles becomes unstable.

[0016] Recently, the inventors of the present invention conducted extensive research and found that the addition of an acetylene glycol surfactant with an HLB value of 9 to 14 can improve the dispersion stability of pigments and resin particles and improve clogging recovery. The acetylene glycol surfactant is compatible with poorly water-soluble low-molecular-weight organic compounds and is resistant to hydrolysis even when the pH is on the alkaline side. Therefore, it is possible to improve the solubility of poorly water-soluble low-molecular-weight organic compounds and maintain the hydrophilic / hydrophobic balance of all components even in inks in alkaline environments. Therefore, it is believed that the dispersion stability of pigments and resin particles can be improved and the formation of foreign matter can be suppressed even in inks containing silicone surfactants and having a pH on the alkaline side.

[0017] Therefore, the inkjet ink composition according to this embodiment can provide excellent image quality and also provide excellent recovery from clogging of the inkjet head.

[0018] Each component contained in the inkjet ink composition according to this embodiment will be described below.

[0019] 1.1 Pigments The inkjet ink composition according to this embodiment contains a pigment. The pigment has the property of being resistant to fading due to light, gas, and the like. Images formed on a recording medium using the pigment not only have excellent image quality, but also excellent water resistance, gas resistance, light resistance, and the like, and exhibit good storage stability. This property is particularly pronounced when images are formed on a low-absorbency recording medium or a non-absorbency recording medium.

[0020] The pigment is not particularly limited, and examples thereof include inorganic pigments and organic pigments. Examples of inorganic pigments include titanium oxide and iron oxide, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method. Examples of organic pigments that can be used include azo pigments, polycyclic pigments, nitro pigments, nitroso pigments, and aniline black. Examples of azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, and quinophthalone pigments.

[0021] Examples of pigments used in black inks include, but are not limited to, furnace black, lamp black, acetylene black, channel black (CI Pigment Black 7), and commercially available products such as No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA77, MA100, and No. 2200B (all trade names, manufactured by Mitsubishi Chemical Corporation), and color black FW1, FW2, FW2V, FW18, FW200, S150, S160, and S17. 0, Pretex 35, U, V, 140U, Special Black 6, 5, 4A, 4, 250, etc. (all trade names, manufactured by Degussa), Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, etc. (all trade names, manufactured by Columbia Carbon), Rigal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, Elftex 12, etc. (all trade names, manufactured by Cabot Japan Co., Ltd.).

[0022] The pigment used in the white ink is not particularly limited, but examples thereof include white inorganic pigments such as CI Pigment White 6, 18, and 21, titanium oxide, zinc oxide, zinc sulfide, antimony oxide, magnesium oxide, and zirconium oxide. In addition to these white inorganic pigments, white organic pigments such as white hollow resin particles and polymer particles can also be used.

[0023] The pigment used in the yellow ink is not particularly limited, but examples thereof include CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, and 180.

[0024] The pigment used in the magenta ink is not particularly limited, but examples thereof include CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48(Ca), 48(Mn), 57(Ca), 57:1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, and 245, and CI Pigment Violet. 19, 23, 32, 33, 36, 38, 43, 50, and solid solutions of multiple pigments mentioned above.

[0025] Pigments used in cyan inks are not particularly limited, but examples thereof include CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 16, 18, 22, 25, 60, 65, and 66, and CI Vat Blue 4 and 60.

[0026] Furthermore, pigments used in color inks other than magenta, cyan, and yellow are not particularly limited, but examples thereof include CI Pigment Green 7 and 10, CI Pigment Brown 3, 5, 25, and 26, and CI Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, and 63.

[0027] The pearl pigment is not particularly limited, but examples thereof include pigments having pearlescent or interference luster, such as titanium dioxide-coated mica, fish scale foil, and bismuth oxychloride.

[0028] The metallic pigment is not particularly limited, but examples thereof include particles of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, copper, and the like, either alone or as an alloy.

[0029] The above pigments may be used alone or in combination of two or more.

[0030] The pigment may be present in the ink composition in a dispersed state, i.e., as a pigment dispersion. In this specification, the term "pigment dispersion" encompasses a pigment dispersion liquid and a pigment slurry (low-viscosity aqueous dispersion).

[0031] Examples of pigment dispersions include, but are not limited to, self-dispersed pigments, polymer-dispersed pigments, and polymer-coated pigments.

[0032] A self-dispersing pigment is a pigment that can be dispersed or dissolved in an aqueous medium without a dispersant. Here, "dispersible or soluble in an aqueous medium without a dispersant" refers to a state in which the pigment is stable in the aqueous medium due to hydrophilic groups on its surface, even without the use of a dispersant to disperse the pigment. Therefore, foaming due to reduced defoaming properties caused by the dispersant is almost nonexistent, making it easy to prepare an ink with excellent ejection stability. Furthermore, since a significant increase in viscosity caused by the dispersant is suppressed, it is possible to incorporate a larger amount of pigment, thereby enabling a sufficient increase in print density, and is therefore easy to handle.

[0033] Examples of the hydrophilic group include -OM, -COOM, -CO-, -SO3M, -SO2M, -SO2NH2, -RSO2M, -PO3HM, -PO3M2, -SON2NHCOR, -NH3, and -NR3.

[0034] In these chemical formulas, M represents a hydrogen atom, an alkali metal, ammonium, a phenyl group which may have a substituent, or an organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms or a naphthyl group which may have a substituent. , each selected independently of the other.

[0035] Self-dispersing pigments are produced by, for example, subjecting a pigment to a physical or chemical treatment to graft (graft) the hydrophilic groups onto the pigment surface. Examples of such physical treatments include vacuum plasma treatment. Examples of such chemical treatments include wet oxidation, in which oxidation is performed using an oxidizing agent in water, and a method in which p-aminobenzoic acid is bonded to the pigment surface to bond a carboxyl group via a phenyl group.

[0036] A polymer-dispersed pigment is a pigment that can be dispersed by polymer dispersion. The polymer used in the polymer-dispersed pigment is not limited to the following, but for example, the glass transition temperature (Tg) of the dispersing polymer used to disperse the pigment is preferably 55°C or less, more preferably 50°C or less. A Tg of 55°C or less may improve the fixability of the ink.

[0037] The weight-average molecular weight of the polymer, as determined by gel permeation chromatography (GPC), is preferably 10,000 or more and 200,000 or less. This may further improve the storage stability of the ink. Here, the weight-average molecular weight (Mw) in this specification can be measured as a polystyrene-equivalent weight-average molecular weight using gel permeation chromatography (GPC) on an L7100 system manufactured by Hitachi, Ltd.

[0038] The polymer is preferably a copolymer of (meth)acrylate and (meth)acrylic acid in an amount of 70% by mass or more among its constituent components, as this tends to provide better ink fixation and gloss. It is also preferred that the polymer is polymerized from 70% by mass or more of a monomer component consisting of at least one of an alkyl (meth)acrylate having 1 to 24 carbon atoms and a cyclic alkyl (meth)acrylate having 3 to 24 carbon atoms. Specific examples of the monomer component include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, and behenyl (meth)acrylate. Other monomer components for polymerization that can be used include hydroxy(meth)acrylates having a hydroxyl group, such as hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, and diethylene glycol(meth)acrylate, urethane(meth)acrylate, and epoxy(meth)acrylate.

[0039] Furthermore, among the polymer-dispersed pigments, pigments coated with a polymer (polymer-coated pigments), i.e., microencapsulated pigments, tend to have excellent ink fixability, gloss, and color reproducibility, and therefore may be preferably used.

[0040] The polymer-coated pigment is obtained by a phase inversion emulsification method. That is, the polymer is dissolved in an organic solvent such as methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, or dibutyl ether. The pigment is added to the resulting solution, and then a neutralizer and water are added and kneaded and dispersed to prepare an oil-in-water dispersion. The organic solvent is then removed from the resulting dispersion to obtain a water-based dispersion. The kneading and dispersion treatment can be carried out using, for example, a ball mill, a roll mill, a bead mill, a high-pressure homogenizer, or a high-speed stirring disperser.

[0041] Preferred neutralizing agents include tertiary amines such as ethylamine and trimethylamine, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, etc. The pH of the resulting aqueous dispersion is preferably 6-10.

[0042] As the polymer for coating the pigment, one having a weight average molecular weight measured by GPC of about 10,000 to 150,000 is preferred in terms of stably dispersing the pigment.

[0043] The content of the pigment (solid content) is, for example, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and particularly preferably 1.5% by mass or more, relative to the total amount of the ink composition. Furthermore, the content of the pigment (solid content) is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, relative to the total amount of the ink composition. A pigment content within the above range may result in better clogging recovery properties.

[0044] The inkjet ink composition according to this embodiment may contain a dye as a coloring material other than the pigment. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. Examples of the dye include CI Acid Yellow 17, 23, 42, 44, 79, and 142; CI Acid Red 52, 80, 82, 249, 254, and 289; CI Acid Blue 9, 45, and 249; CI Acid Black 1, 2, 24, and 94; CI Food Black 1 and 2; CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, and 144. 173, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Directed Black 19, 38, 51, 71, 154, 168, 171, 195, CI Reactive Red 14, 32, 55, 79, 249, CI Reactive Black 3, 4, 35, etc.

[0045] 1.2 Resin particles The inkjet ink composition according to this embodiment contains resin particles. The resin particles function as a fixing resin, improving the adhesion and abrasion resistance of the ink components adhered to a recording medium. The resin particles may be in the form of a powder, but are preferably in the form of an emulsion.

[0046] Examples of the resin of the resin particles include urethane-based resins, acrylic-based resins, fluorene-based resins, polyolefin-based resins, rosin-modified resins, terpene-based resins, polyester-based resins, polyamide-based resins, epoxy-based resins, vinyl chloride-based resins, ethylene vinyl acetate-based resins, vinyl acetate resins, butadiene resins, styrene resins, cross-linked acrylic resins, cross-linked styrene resins, benzoguanamine resins, phenolic resins, silicone resins, epoxy resins, paraffin resins, and fluororesins.

[0047] Urethane resin is a general term for resins having a urethane bond. As the urethane resin, polyether type urethane resins containing ether bonds in the main chain other than urethane bonds, polyester type urethane resins containing ester bonds in the main chain, polycarbonate type urethane resins containing carbonate bonds in the main chain, etc. may be used. As the urethane resin, commercially available products may be used, for example, Superflex 210, 460, 460s, 840, E-4000 (trade names, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D- The adhesive may be selected from commercially available products such as 4080, D-4200, D-6300, D-6455 (trade names, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Takelac WS-6020, WS-6021, W-512-A-6 (trade names, manufactured by Mitsui Chemicals Polyurethanes Inc.), Sancure 2710 (trade name, manufactured by Lubrizol), and Permarin UA-150 (trade name, manufactured by Sanyo Chemical Industries, Ltd.).

[0048] 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.

[0049] The acrylic resin may be a commercially available product, and may be selected from, for example, FK-854 (trade name, manufactured by Chuo Rika Kogyo Co., Ltd.), Mowinyl 952B, 718A (trade names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Nipol LX852, LX874 (trade names, manufactured by Nippon Zeon Co., Ltd.), Polysol AT860 (manufactured by Showa Denko KK), Boncoat AN-1190S, YG-651, AC-501, AN-1170, 4001 (trade names, acrylic resin emulsions, manufactured by DIC Corporation), and the like.

[0050] In this specification, the acrylic resin may be a styrene-acrylic resin as described above.

[0051] 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. As the styrene-acrylic resin, commercially available products may be used, and examples thereof include JONCRYL 62J, 7100, 390, 711, 511, 7001, 631, 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, and 7610 (trade names, manufactured by BASF), and Mowinyl 966A and 975N (trade names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

[0052] The vinyl chloride resin may be a vinyl chloride-vinyl acetate copolymer.

[0053] The polyolefin resin has an olefin such as ethylene, propylene, or butylene in its structural skeleton, and known polyolefin resins can be appropriately selected and used. As the polyolefin resin, commercially available products can be used, and may be selected from, for example, Arrowbase CB-1200, CD-1200 (trade names, manufactured by Unitika Ltd.), Hitec E-6500 (trade name, manufactured by Toho Chemical Co., Ltd., polyethylene wax emulsion), and SN-2002 (trade name, manufactured by Toho Chemical Co., Ltd., polyester resin emulsion).

[0054] Commercially available examples of resin emulsions include Microgel E-1002 and E-5002 (product names of Nippon Paint Co., Ltd., styrene-acrylic resin emulsions), Boncoat AN-1190S, YG-651, AC-501, AN-1170, 4001, and 5454 (product names of DIC Corporation, styrene-acrylic resin emulsions), Polysol AM-710, AM-920, AM-2300, AP-4735, AT-860, and PSASE-4. 210E (acrylic resin emulsion), Polysol AP-7020 (styrene-acrylic resin emulsion), Polysol SH-502 (vinyl acetate resin emulsion), Polysol AD-13, AD-2, AD-10, AD-96, AD-17, AD-70 (ethylene-vinyl acetate resin emulsion), Polysol PSASE-6010 (ethylene-vinyl acetate resin emulsion) (trade name, manufactured by Showa Denko K.K.), Polysol SAE1014 (styrene-acrylic resin emulsion, manufactured by Japan Zeon Corporation), Saivinol SK-200 (trade name, acrylic resin emulsion, Saiden Chemical Co., Ltd.), AE-120A (trade name, acrylic resin emulsion, manufactured by JSR Corporation), AE373D (trade name, carboxy-modified styrene-acrylic resin emulsion, manufactured by E-Tech Co., Ltd.), Seikadyne 1900W (trade name, ethylene-vinyl acetate resin emulsion, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Vinyblan 2682 (acrylic resin emulsion), Vinyblan 2886 (vinyl acetate-acrylic resin emulsion), Niblan 5202 (acrylic acetate resin emulsion) (trade name, manufactured by Nissin Chemical Industry Co., Ltd.), Vinyblan 700, 2586 (trade name, manufactured by Nissin Chemical Industry Co., Ltd.), Eliter KA-5071S, KT-8803, KT-9204, KT-8701, KT-8904, KT-0507 (trade name, polyester resin emulsion, manufactured by Unitika Ltd.), Hitec E-6500 (trade name, polyethylene wax emulsion, manufactured by Toho Chemical Industry Co., Ltd.), SN-2002 (trade name, polyester resin emulsion, manufactured by Toho Chemical Industry Co., Ltd.), Takelac W- 6020, W-635, W-6061, W-605, W-635, W-6021 (trade names of Mitsui Chemicals Polyurethanes, Inc., urethane-based resin emulsions), Superflex 870, 800, 150, 420, 460, 470, 610, 620, 700 (trade names of Daiichi Kogyo Seiyaku Co., Ltd., urethane-based resin emulsions), Permarin UA-150 (trade name of Sanyo Chemical Industries, Ltd., urethane-based resin emulsions), Sancure 2710 (trade name of Lubrizol Japan, urethane-based resin emulsions), NeoRez R-9660, R-9637, R-940 (trade name of Kusumoto Chemicals Co., Ltd., urethane-based resin emulsions), Adeka Bontiter HUX-380,290K (manufactured by ADEKA Corporation, urethane resin emulsion), Mowinyl 966A, Mowinyl 7320 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 631, 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 Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane: manufactured by DIC Corporation), and the like may be selected and used.

[0055] Among these resins, acrylic resins and polyolefin resins are preferred, and a combination of acrylic resins and polyolefin resins is more preferred, as such resins tend to have better clogging recovery properties.

[0056] The glass transition temperature (Tg) of the resin particles is preferably 60°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and particularly preferably 90°C or higher. On the other hand, it is preferably 120°C or lower, more preferably 115°C or lower, even more preferably 110°C or lower, and particularly preferably 105°C or lower. When the glass transition temperature (Tg) of the resin particles is within the above range, the resin particles may have better clogging recovery properties. The glass transition temperature (Tg) of the resin particles can be confirmed by a standard method such as differential scanning calorimetry (DSC).

[0057] The content of the resin particles (solid content) is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and particularly preferably 3% by mass or more, relative to the total amount of the ink composition. The content of the resin particles (solid content) is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 7% by mass or less, relative to the total amount of the ink composition. It is particularly preferred that:

[0058] 1.3 Surfactants The inkjet ink composition according to this embodiment contains a surfactant, which includes a silicone surfactant and an acetylene glycol surfactant having an HLB value of 9 to 14.

[0059] The total content of the acetylene glycol surfactant having an HLB value of 9 to 14 and the silicone surfactant is preferably 0.1 to 1% by mass relative to the total amount of the ink composition. When the total content is within this range, the balance between clogging recovery and image quality is excellent, and both clogging recovery and image quality tend to be good. The lower limit of this total content is more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, particularly preferably 0.4% by mass or more, and even more particularly preferably 0.5% by mass or more, relative to the total amount of the ink composition. The upper limit of this total content is more preferably 0.9% by mass or less, even more preferably 0.8% by mass or less, and particularly preferably 0.7% by mass or less, relative to the total amount of the ink composition. It is preferable that the total surfactant content be within the above range, since this can prevent phase separation in the ink and destabilize the dispersion of the pigment and resin.

[0060] The ratio of the content of the silicone surfactant to the content of the acetylene glycol surfactant having an HLB value of 9 to 14 (content of the silicone surfactant / content of the acetylene glycol surfactant having an HLB value of 9 to 14) is preferably 0.5 to 4, more preferably 1 to 3.5, even more preferably greater than 1 to 3.0, and even more preferably 1.5 to 2.5. The function of the acetylene glycol surfactant is mainly to ensure clogging recovery and makes little contribution to improving image quality, so from the perspective of improving image quality, it is preferable that the content of the silicone surfactant is greater than the content of the acetylene glycol surfactant.

[0061] 1.3.1 Acetylene glycol surfactants The surfactant includes an acetylene glycol surfactant having an HLB value of 9 to 14. The acetylene glycol surfactant has excellent compatibility with poorly water-soluble low-molecular-weight organic compounds and is resistant to hydrolysis even at a pH on the alkaline side.

[0062] As used herein, the term "HLB value" refers to the value of hydrophilicity and The HLB value is a numerical representation of the hydrophilic-hydrophobic balance of a compound. Here, the HLB value is a value calculated by the Griffin method and can be calculated using the following formula (H): HLB value = 20 × total formula weight of hydrophilic moieties / molecular weight (H)

[0063] The lower limit of the HLB value of the acetylene glycol surfactant is 9 or more, preferably 10 or more, more preferably 11 or more, even more preferably 12 or more, and particularly preferably 13 or more. If the HLB value is lower than 9, the acetylene glycol surfactant has poor water solubility, and the acetylene glycol surfactant is prone to becoming foreign matter, which actually worsens the dispersion stability of pigments and the like. The upper limit of the HLB value of the acetylene glycol surfactant is 14. If the HLB value is higher than 14, compatibility with poorly water-soluble low-molecular-weight organic compounds cannot be obtained.

[0064] Examples of acetylene glycol surfactants having an HLB value of 9 to 14 include Olfine E1010 (HLB value 13 to 14), Olfine EXP. 4200 (HLB value 10 to 13), and Olfine EXP. 4123 (HLB value 10 to 13) [trade names, manufactured by Nissin Chemical Industry Co., Ltd.].

[0065] The content of the acetylene glycol surfactant having an HLB value of 9 to 14 is preferably 0.05 to 0.5 mass%, more preferably 0.1 to 0.4 mass%, and even more preferably 0.15 to 0.3 mass%, relative to the total amount of the ink composition. When the content of the acetylene glycol surfactant having an HLB value of 9 to 14 is within the above range, clogging recovery properties tend to be better.

[0066] 1.3.2 Silicone surfactants The surfactant includes a silicone-based surfactant. Silicone-based surfactants have excellent properties for improving the wetting and spreading of water-based inks on low- or non-absorbent recording media, and by incorporating them into the ink together with a poorly water-soluble low-molecular-weight compound, excellent image quality can be obtained. However, the above-mentioned acetylene glycol-based surfactant alone cannot ensure sufficient wetting and spreading of the ink.

[0067] 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 polyether-modified organosiloxanes include, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-349, and BYK-3420 (all trade names, manufactured by BYK-Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, and KF-355A. Examples of such surfactants include F-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG503A and Silface SAG014 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), and TEGO wet 270 (trade name, manufactured by Evonik).

[0068] The cloud point of the silicone surfactant is preferably 40°C or higher. A cloud point of 40°C or higher tends to result in excellent solubility in water and excellent clogging recovery properties. The lower limit of the cloud point is more preferably 45°C or higher, and even more preferably 50°C or higher. The upper limit of the cloud point is not particularly limited, but is, for example, preferably 100°C or lower, more preferably 80°C or lower, and even more preferably 60°C or lower.

[0069] The cloud point can be measured, for example, as follows. First, a solution prepared by mixing silicone surfactant, propylene glycol, and water in a mass ratio of 1:9:90 is stirred for at least 30 minutes. 20 g of the mixture is then placed in a 30 mL sample bottle and left for one day in a thermostatic bath at a predetermined temperature. After leaving it for one day, if the mixture is visually observed and mixed (the liquid is transparent), it can be determined that the mixture has a cloud point above the predetermined temperature. On the other hand, if the mixture is cloudy or contains separated matter, it can be determined that the mixture does not have a cloud point above the predetermined temperature.

[0070] The content of the silicone surfactant is preferably 0.1 to 1.0% by mass, more preferably 0.2 to 0.8% by mass, and even more preferably 0.3 to 0.5% by mass, relative to the total amount of the ink composition. When the content of the silicone surfactant is within the above range, the image quality tends to be better.

[0071] 1.3.3 Other surfactants The surfactant may contain surfactants other than those mentioned above. Examples of other surfactants include acetylene glycol surfactants and fluorine-based surfactants having an HLB value of less than 9 or more than 14.

[0072] As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer. An example is BYK-340 (trade name, manufactured by BYK Japan Co., Ltd.).

[0073] 1.4 Poorly water-soluble low-molecular organic compounds The inkjet ink composition according to this embodiment contains a poorly water-soluble low-molecular-weight organic compound, which is either an alkanediol or a glycol ether and has a solubility in water of 10 g / 100 g of water or less. The poorly water-soluble low-molecular-weight organic compound has relatively high hydrophobicity. Therefore, inks containing this compound have a high affinity for low- or non-absorbent recording media, and tend to wet and spread easily.

[0074] The upper limit of the solubility of the poorly water-soluble low-molecular-weight organic compound in water is 10 g / 100 g of water or less, preferably 8 g / 100 g of water or less, more preferably 6 g / 100 g of water or less, even more preferably 4 g / 100 g of water or less, particularly preferably 2 g / 100 g of water or less, and more particularly preferably 1 g / 100 g of water or less. The lower limit of the solubility of the poorly water-soluble low-molecular-weight organic compound in water is not particularly limited, and may be 0 g / 100 g or more of water, 0.01 g / 100 g or more of water, 0.1 g / 100 g or more of water, 0.5 g / 100 g or more of water, or 0.7 g / 100 g or more of water.

[0075] The solubility of a poorly water-soluble low-molecular-weight organic compound in water can be determined, for example, by the following method. First, a predetermined amount of the compound is mixed with 100 g of water in an environment of 20°C and stirred for 30 minutes. After stirring, a compound that is liquid at room temperature is judged to be soluble if there is no phase separation or sea-island structure. Furthermore, a compound that is solid at room temperature is judged to be soluble if there is no residue remaining. In this way, when a predetermined amount of compound is mixed with 100 g of water, the largest predetermined amount among the predetermined amounts that are determined to be dissolved is taken as the solubility.

[0076] In the present invention, the term "low molecular weight" refers to a molecular weight of 300 or less.

[0077] The upper limit of the molecular weight of the poorly water-soluble low-molecular-weight organic compound is 300 or less, preferably 250 or less, and more preferably 200 or less. There is no limitation on the lower limit of the molecular weight, but for example, 50 or more is preferred, and 100 or more is more preferred.

[0078] The normal boiling point of the poorly water-soluble low-molecular-weight organic compound is not particularly limited, but is preferably 300° C. or lower, more preferably 280° C. or lower, and even more preferably 270° C. or lower. The lower limit of the normal boiling point is not particularly limited, but is preferably 100° C. or higher, more preferably 150° C. or higher, even more preferably 200° C. or higher, and particularly preferably 250° C. or higher.

[0079] The melting point of the poorly water-soluble low-molecular organic compound is preferably 130°C or lower, and more preferably -120°C or higher, more preferably -50 to 60°C, and even more preferably -30 to 50°C.

[0080] Examples of poorly water-soluble low-molecular-weight organic compounds include organic solvents (liquid at room temperature) and compounds that are solid at room temperature.

[0081] The content of the poorly water-soluble low-molecular-weight organic compound, which is either an alkanediol or a glycol ether and has a solubility in water of 10 g / 100 g of water or less, is preferably 0.1 to 2% by mass relative to the total amount of the ink composition. From the viewpoint of tending to provide better image quality, the lower limit of the content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.4% by mass or more, relative to the total amount of the ink composition. Furthermore, from the viewpoint of tending to provide better clogging recovery, the upper limit of the content is 2% by mass or more. The concentration is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, particularly preferably 0.8% by mass or less, and more particularly preferably 0.6% by mass or less.

[0082] 1.4.1 Alkanediols The inkjet ink composition according to this embodiment preferably contains a poorly water-soluble low-molecular-weight organic compound that is an alkanediol and has a solubility in water of 10 g / 100 g water or less. When the poorly water-soluble low-molecular-weight organic compound is an alkanediol, the ink tends to wet and spread more easily on the recording medium, resulting in better image quality. Furthermore, the ink tends to be less likely to produce foreign matter when dried, resulting in better clogging recovery.

[0083] Examples of alkanediols, which are poorly water-soluble low-molecular-weight organic compounds, include aliphatic diols, alicyclic diols, etc. Examples of aliphatic diols include 1,3-alkanediols and aliphatic diols other than 1,3-alkanediols.

[0084] Examples of the aliphatic diols include aliphatic diols having 6 or more carbon atoms, and further include aliphatic diols having 8 to 20 carbon atoms.

[0085] Examples of 1,3-alkanediols include 2,2-diethyl-1,3-propanediol (DEPOD, normal boiling point 240°C, state at 25°C: solid, solubility 10.0 [g / 100g of water]), 2-methyl-2-propyl-1,3-propanediol (MPPD, normal boiling point 230°C, melting point 57°C, solubility 7.5 [g / 100g of water]), 2-butyl-2-ethyl-1,3-propanediol (BEPG, normal boiling point 264°C, melting point 41°C, solubility 0.9 [g / 100g of water]), and 2,2-diisobutyl-1,3- Examples include propanediol (DIBPD, normal boiling point 253°C, melting point 77°C, solubility 0.5 [g / 100g water]), 2,2-dibutyl-1,3-propanediol (DBPD, normal boiling point 269°C, solubility 0.2 [g / 100g water]), 2,2,4-trimethyl-1,3-pentanediol (TMPD, normal boiling point 232°C, melting point 54°C, solubility 1.9 [g / 100g water]), and 2-ethyl-1,3-hexanediol (EHD, normal boiling point 244°C, melting point -40°C, solubility 4.2 [g / 100g water]).

[0086] Examples of aliphatic diols other than 1,3-alkanediols include 1,2-octanediol (1,2OD, normal boiling point 267°C, melting point 28°C, solubility 0.3 [g / 100g water]), 1,9-nonanediol (1,9ND, normal boiling point 289°C, melting point 46°C, solubility 0.6 [g / 100g water]), 1,2-decanediol (normal boiling point 279°C, melting point 49°C, solubility 0.1 [g / 100g water]), and 2,4-diethyl-1,5-pentanediol (DEPD, normal boiling point 257°C, liquid (25°C), solubility 1.0 [g / 100g water]).

[0087] Examples of alicyclic diols include 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD, normal boiling point 220°C, melting point 126°C, solubility 6.1 [g / 100 g of water]) and 1,4-cyclohexanedimethanol (CHDM, normal boiling point 286°C, melting point 35°C, solubility 0.8 [g / 100 g of water]). Examples of the alicyclic structure of the alicyclic diols include alicyclic diols having an alicyclic ring with 4 to 10 carbon atoms. The number of carbon atoms in the molecule of the alicyclic diols may be the same as the number of carbon atoms in the aliphatic diols.

[0088] Among these, from the viewpoint of tending to provide better image quality (wetting and spreading) and clogging recovery, the alkanediol is preferably at least one selected from 2-butyl-2-ethyl-1,3-propanediol (BEPG) and 1,2-octanediol (1,2OD). I wish.

[0089] Among the above 1,3-alkanediols, 1,3-alkanediols represented by the following general formula (1) are preferred, as they tend to provide better image quality and clogging recovery. [ka] (In formula (1), R1, R2, and R3 are independently hydrogen or an alkyl group. The total number of carbon atoms in R1, R2, and R3 is 3 to 9.)

[0090] Furthermore, in the above formula, it is preferable that R1 and R2 are not simultaneously hydrogen. When R1, R2, and R3 are alkyl groups, the alkyl groups independently preferably have 1 to 5 carbon atoms, more preferably 2 to 4 carbon atoms. The total number of carbon atoms in R1, R2, and R3 is preferably 4 to 5, more preferably 4 to 6. It is preferable that R3 is an alkyl group.

[0091] Examples of the 1,3-alkanediols represented by the general formula (1) above include 2-methyl-2-propyl-1,3-propanediol (MPPD), 2-butyl-2-ethyl-1,3-propanediol (BEPG), 2,2,4-trimethyl-1,3-pentanediol (TMPD), and 2-ethyl-1,3-hexanediol (EHD), with 2-butyl-2-ethyl-1,3-propanediol (BEPG) being preferred.

[0092] 1.4.2 Glycol ethers Examples of glycol ethers, which are poorly water-soluble low-molecular-weight organic compounds having a solubility in water of 10 g / 100 g of water or less, include glycol monoethers and glycol diethers.

[0093] Examples of the glycol monoethers include ethylene glycol monohexyl ether (EGHE, boiling point 208°C, melting point -45°C, solubility 1.0 [g / 100g of water]), ethylene glycol mono 2-ethylhexyl ether (EHG, boiling point 229°C, melting point -105°C, solubility 0.1 [g / 100g of water]), diethylene glycol monohexyl ether (HDG, boiling point 259°C, liquid (25°C), solubility 1.7 [g / 100g of water]), diethylene glycol monohexyl ether (DI ... Examples include ethylene glycol mono-2-ethylhexyl ether (EHDG, boiling point 277°C, melting point -82°C, solubility 0.5 [g / 100g water], also known as 2-ethylhexyl diglycol), dipropylene glycol monobutyl ether (BPDG, boiling point 230°C, liquid (25°C), solubility 4.0 [g / 100g water]), and tripropylene glycol monobutyl ether (BPTG, boiling point 276°C, solubility 4.0 [g / 100g water]).

[0094] Examples of the glycol diethers include diethylene glycol butyl methyl ether (BMTG, boiling point 212°C, liquid (25°C)), diethylene glycol dibutyl ether (DBDG, boiling point 256°C, melting point -60°C, solubility 0.3 [g / 100g water]), and the like.

[0095] Among these glycol ethers, glycol ethers with 6 or more carbon atoms are Examples of glycol ethers having 6 or more carbon atoms include ethylene glycol monohexyl ether (EGHE), ethylene glycol mono-2-ethylhexyl ether (EHG), diethylene glycol monohexyl ether (HDG), diethylene glycol mono-2-ethylhexyl ether (EHDG), dipropylene glycol monobutyl ether (BPDG), tripropylene glycol monobutyl ether (BPTG), diethylene glycol butyl methyl ether (BMTG), and diethylene glycol dibutyl ether (DBDG).

[0096] 1.5 water The inkjet ink composition according to this embodiment is a water-based composition, which contains at least water as a solvent component of the composition.

[0097] The content of water in the liquid medium component is preferably 30 to 100 mass %, more preferably 40 to 90 mass %, and even more preferably 50 to 80 mass %. The liquid medium is a solvent component such as water or a water-soluble low-molecular-weight organic compound.

[0098] The water content is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more, relative to the total amount of the ink composition. There is no particular upper limit to the water content, but for example, it is preferably 99% by mass or less, even more preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less, relative to the total amount of the ink composition.

[0099] Examples of 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, the use of water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can suppress the growth of bacteria and fungi when the inkjet ink composition is stored for a long period of time.

[0100] 1.6 Water-soluble low molecular weight organic compounds The inkjet ink composition according to this embodiment may contain a water-soluble low-molecular-weight organic compound. The water-soluble low-molecular-weight organic compound has the property of improving the water solubility of the above-mentioned poorly water-soluble low-molecular-weight organic compound. When the ink contains a water-soluble low-molecular-weight organic compound, the above-mentioned poorly water-soluble low-molecular-weight organic compound is prevented from becoming a foreign substance, and clogging recovery tends to be more excellent. Examples of the water-soluble low-molecular-weight organic compound include those that are liquid at room temperature and those that are solid at room temperature.

[0101] "Water-soluble" in the context of a water-soluble low-molecular-weight organic compound means that the solubility in water at 20°C is greater than 10 g / 100 g of water. The solubility of a water-soluble low-molecular-weight organic compound in water at 20°C is preferably 11 g / 100 g of water or more, more preferably 50 g / 100 g of water or more. The upper limit is not limited and may be infinite. The solubility of a water-soluble low-molecular-weight organic compound can be determined in the same manner as described above.

[0102] As described above, the term "low molecular weight" in the water-soluble low molecular weight organic compound refers to a molecular weight of 300 or less. The upper limit of the molecular weight of the water-soluble low molecular weight organic compound is preferably 250 or less, more preferably 200 or less. There is no particular lower limit, but a lower limit of 50 or more is preferred.

[0103] The water-soluble low-molecular-weight organic compound is preferably a compound that is completely miscible with water or a compound that is miscible with water. Here, "completely miscible with water" refers to the case where water and the organic compound are mutually soluble, that is, the case where the solubility of the organic compound in 100 g of water at 20°C is infinite. Also, "miscible with water" refers to the case where water and the organic compound have a finite solubility, and at least This also refers to the case where the solubility of the organic compound in 100 g of water at 20°C is more than 10 g.

[0104] The water-soluble low-molecular-weight organic compound preferably includes one having a normal boiling point of 150 to 350° C., more preferably 150 to 320° C. The water-soluble low-molecular-weight organic compound preferably includes a compound having a melting point of 90° C. or less, more preferably 80° C. or less. The lower limit of the melting point is not particularly limited, but is preferably −70° C. or more.

[0105] Examples of the water-soluble low-molecular organic compound include resin-soluble substances, polyols, glycol ethers, alkanolamines, etc. If necessary, other water-soluble low-molecular organic compounds may be contained.

[0106] Among these, the water-soluble low-molecular-weight organic compound is preferably a resin-dissolving substance, a polyol, or an alkanolamine. More preferably, the water-soluble low-molecular-weight organic compound is a resin-dissolving substance, which is any one of an amide, a sulfur-containing solvent, and a cyclic ether, having a normal boiling point of more than 250°C, or an alkanolamine, or a polyol having a normal boiling point of 250°C or lower.

[0107] The inkjet ink composition according to this embodiment preferably contains 50% by mass or less of the water-soluble low-molecular-weight organic compound, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the ink composition. The lower limit is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total amount of the ink composition. When the water-soluble low-molecular-weight organic compound is contained within the above range, the compatibility between the water-soluble low-molecular-weight organic compound and the poorly water-soluble low-molecular-weight organic compound becomes better, and the clogging recovery property tends to be better.

[0108] 1.6.1 Resin dissolved substances Examples of resin-dissolving substances include amides, sulfur-containing solvents, cyclic ethers, etc. In particular, from the viewpoint of further improving the abrasion resistance of recorded matter, it is preferable to contain any of amides, sulfur-containing solvents, and cyclic ethers having a standard boiling point of more than 250° C., and it is more preferable to contain amides having a standard boiling point of more than 250° C. Note that resin-dissolving substances are organic compounds that have the function of dissolving resins and improving abrasion resistance, but are not limited to this function.

[0109] (amides) Examples of amides include cyclic amides (lactams) such as 2-pyrrolidone (2P), 2-piperidone, ε-caprolactam (CPL, normal boiling point 267°C, solid (25°C)), N-methyl-ε-caprolactam, N-cyclohexyl-2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, N-butylpyrrolidone, 5-methyl-2-pyrrolidone, β-propiolactam, and ω-heptalactam; N,N-dimethylacetoacetamide, N,N-diethylacetoacetamide, N-methylacetoacetamide, N,N-dimethylisobutyric acid amide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, and N,N-dimethylpropanol; N,N-dimethylpropanamide (DMPA), 3-n-butoxy-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-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 and 3-tert-butoxy-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. Among these, from the viewpoint of further improving the abrasion resistance of recorded matter, any of 2-pyrrolidone (2P), ε-caprolactam (CPL), and 3-methoxy-N,N-dimethylpropanamide (DMPA) is preferred, and ε-caprolactam (CPL) is more preferred.

[0110] (Sulfur-containing solvent) Examples of sulfur-containing solvents include 3-methylsulfolane, sulfolane, ethyl isopropyl sulfone, ethyl methyl sulfone, dimethyl sulfone, dimethyl sulfoxide (DMSO), diethyl sulfoxide, tetramethylene sulfoxide, and methyl phenyl sulfoxide. Among these, dimethyl sulfoxide (DMSO) is more preferable from the viewpoint of further improving the abrasion resistance of the recorded matter.

[0111] (cyclic ethers) Examples of cyclic ethers include isosorbide dimethyl ether, 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol (DMHD), 2-hydroxymethyloxetane, tetrahydrofurfuryl alcohol, solketal, glycerol formal, 1,4-dioxane-2,3-diol, and dihydrolevoglucosenone. Among these, 3-ethyl-3-oxetanemethanol (DMHD) is more preferable from the viewpoint of further improving the abrasion resistance of recorded matter.

[0112] 1.6.2 Polyols Polyols have two or more hydroxyl groups in the molecule, and examples of polyols include diols and polyols of triol or higher.

[0113] The polyols preferably have 15 or less carbon atoms in the molecule, more preferably 10 or less, and even more preferably 6 or less. There is no particular lower limit to the number of carbon atoms, but it is preferably 2 or more, and more preferably 4 or more.

[0114] The normal boiling point of the polyols is preferably 250°C or lower, more preferably 150 to 250°C.

[0115] (Diols) Diols have two hydroxyl groups in the molecule. Examples of diols include alkanediols and condensates (having two hydroxyl groups in the molecule) in which two or more molecules of alkanediols are intermolecularly condensed via the hydroxyl groups.

[0116] The glycol unit in the alkanediol or in the condensate in which two or more molecules of alkanediol are intermolecularly condensed via the hydroxyl groups thereof preferably has 2 to 10 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 4 to 6 carbon atoms.

[0117] Examples of alkanediols include ethylene glycol (standard boiling point 198°C, miscible with water), 1,2-propanediol (propylene glycol: PG) (standard boiling point 188°C, completely miscible with water), 1,2-butanediol (standard boiling point 194°C, miscible with water), 1,2-pentanediol (standard boiling point 210°C, miscible with water), 1,2-hexanediol (1,2 HD, standard boiling point 224°C, completely miscible with water), 1,3-propanediol (standard boiling point 214°C, completely miscible with water), 1,4-butanediol (standard boiling point 228°C, completely miscible with water), 2,3-butanediol (standard boiling point 177°C, miscible with water), 1,3-butylene glycol (standard boiling point 207°C, completely miscible with water), 3-methyl-1,3-butanediol (standard boiling point 203°C, completely miscible with water), 2-methyl-1,3-propanediol (standard boiling point 214°C, completely miscible with water), 2,2-dimethyl-1, Examples include 3-propanediol (standard boiling point 208°C, solubility 83 [g / 100g water]), 2-methylpentane-2,4-diol (standard boiling point 197°C, completely miscible with water), 2,5-dimethyl-2,5-hexanediol (standard boiling point 218°C, solubility 14 [g / 100g water]), 1,5-pentanediol (standard boiling point 242°C, miscible with water), 3-methyl-1,5-pentanediol (standard boiling point 250°C, completely miscible with water), and 1,6-hexanediol (standard boiling point 250°C, miscible with water).

[0118] Among the alkanediols, those having 2 or more carbon atoms are preferred. Further, those having 2 to 10 carbon atoms, preferably 3 to 8 carbon atoms, and more preferably 4 to 6 carbon atoms are preferred. In particular, alkanediols having 4 or more carbon atoms can further improve the water solubility of poorly water-soluble low-molecular organic compounds, and tend to have better clogging recovery properties. The inkjet ink composition according to this embodiment preferably contains 1 to 5 mass % of alkanediols having 4 or more carbon atoms as the water-soluble low-molecular-weight organic compound, relative to the total amount of the ink composition. In this case, the water solubility of the poorly water-soluble low-molecular-weight organic compound can be further improved, and clogging recovery tends to be more excellent. The content of alkanediols having 4 or more carbon atoms is more preferably 1 to 4 mass %, and even more preferably 1 to 3 mass %, relative to the total amount of the ink composition. In particular, it is more preferable that the content of alkanediols having 4 to 6 carbon atoms is within the above range.

[0119] 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 (standard boiling point 244°C, completely miscible with water) and dipropylene glycol (standard boiling point 227°C, completely miscible with water), and trialkylene glycols such as triethylene glycol (standard boiling point 276°C, completely miscible with water) and tripropylene glycol (standard boiling point 273°C, completely miscible with water).

[0120] It is preferable that the ink contains alkanediols having 3 or less carbon atoms, or condensates formed by intermolecular condensation of hydroxyl groups between two or more molecules of alkanediols, as this provides better clogging recovery properties, etc. The total content of alkanediols having 3 or less carbon atoms, or condensates formed by intermolecular condensation of hydroxyl groups between two or more molecules of alkanediols, is preferably 1 to 30% by mass, more preferably 5 to 25% by mass, and even more preferably 10 to 20% by mass, of the total amount of the ink composition. In particular, it is more preferable that the content of alkanediols having 3 or less carbon atoms is within the above range.

[0121] (triol or higher polyol) A triol or higher polyol is one having three or more hydroxyl groups in its molecule. Examples include compounds having three or more hydroxyl groups and having an alkane or polyether structure as the backbone. Examples of such compounds include glycerin (standard boiling point 290°C, miscible with water), trimethylolethane (standard boiling point 283°C, solubility approximately 60 [g / 100g of water]), trimethylolpropane (standard boiling point 295°C, completely miscible with water), and 1,2,6-hexanetriol (completely miscible with water).

[0122] Among the above polyols, alkanediols having a standard boiling point of 150 to 250°C and 10 or less carbon atoms are more preferred, and alkanediols having a standard boiling point of 150 to 250°C and 4 to 6 carbon atoms are even more preferred.

[0123] The inkjet ink composition according to this embodiment preferably contains 30% by mass or less, and more preferably 25% by mass or less, of the water-soluble low-molecular-weight organic compound polyols relative to the total amount of the ink composition. The lower limit is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to the total amount of the ink composition. Among the polyols, polyols having a standard boiling point of 150 to 250°C are preferred, alkanediols having a standard boiling point of 150 to 250°C are more preferred, alkanediols having a standard boiling point of 150 to 250°C and 10 or less carbon atoms are even more preferred, and alkanediols having a standard boiling point of 150 to 250°C and 4 to 6 carbon atoms are particularly preferred, and the content of these may be within the above ranges. When the water-soluble low-molecular organic compound is contained within the above range, the clogging recovery property tends to be improved.

[0124] The inkjet ink composition according to this embodiment preferably contains no more than 3% by mass of water-soluble low-molecular-weight organic compounds, which are polyols with a normal boiling point above 280° C., relative to the total amount of the ink composition, more preferably no more than 1% by mass, and even more preferably no more than 0.5% by mass. In this case, the ink may or may not contain polyols with a standard boiling point above 280°C, and even if it does, the content is below the above range. When the content of polyols with a standard boiling point above 280°C is within the above range, a significant decrease in the drying speed of the ink can be prevented, and as a result, even when recording on a low- or non-absorbent recording medium, a decrease in image fixability tends to be prevented. Furthermore, sufficient drying tends to be achieved even when the temperature of the recording medium during heat drying is relatively low. Examples of such polyols with a standard boiling point above 280°C include glycerin (standard boiling point 290°C).

[0125] 1.6.3 Glycol ethers Glycol ethers are compounds in which one or more hydroxyl groups of glycol are etherified. As glycol ethers, monoethers or diethers of alkylene glycols are preferred. As the etherified ether, alkyl ethers are preferred. The alkylene of the alkylene glycol and the alkyl of the alkyl ether constituting the glycol ethers each preferably have 1 to 5 carbon atoms, more preferably 2 to 4 carbon atoms. Glycol ethers having a normal boiling point of 150 to 250°C are preferred.

[0126] Examples of glycol ethers include alkylene glycol monoalkyl ethers, such as ethylene glycol monomethyl ether (completely miscible with water), ethylene glycol monoethyl ether (miscible with water), ethylene glycol monoisopropyl ether (solubility 100 [g / 100g of water]), ethylene glycol monopropyl ether (miscible with water), ethylene glycol monoisobutyl ether (solubility 75.5 [g / 100g of water]), ethylene glycol mono-tert-butyl ether (miscible with water), ethylene glycol monobutyl ether (solubility 100 [g / 100g of water]), diethylene glycol monomethyl ether (completely miscible with water), diethylene glycol monoethyl ether (completely miscible with water ... Ethylene glycol monoisopropyl ether (miscible with water), diethylene glycol monoisobutyl ether (completely miscible with water), diethylene glycol monobutyl ether (completely miscible with water), triethylene glycol monomethyl ether (completely miscible with water), triethylene glycol monoethyl ether (completely miscible with water), triethylene glycol monobutyl ether (miscible with water), tetraethylene glycol monomethyl ether (miscible with water), propylene glycol monomethyl ether (miscible with water), propylene glycol monoethyl ether (completely miscible with water), propylene glycol monopropyl ether (miscible with water), dipropylene glycol monomethyl ether (completely miscible with water), dipropylene glycol Examples include 1,3-propanediol monomethyl ether (solubility 19 [g / 100g water]), tripropylene glycol monomethyl ether (completely miscible with water), 1,3-propanediol monomethyl ether (3-methoxy-1-propanol) (completely miscible with water), and 1,3-butylene glycol-3-monomethyl ether (3-methoxy-1-butanol) (miscible with water).

[0127] Examples of glycol ethers include alkylene glycol dialkyl ethers (glymes), such as ethylene glycol dimethyl ether (completely miscible with water), diethylene glycol dimethyl ether (completely miscible with water), diethylene glycol methyl ethyl ether (completely miscible with water), diethylene glycol diethyl ether (completely miscible with water), triethylene glycol dimethyl ether (completely miscible with water), tetraethylene glycol dimethyl ether (completely miscible with water), dipropylene glycol dimethyl ether (solubility: 52.6 [g / 100 g of water]), and tripropylene glycol dimethyl ether (solubility: 23.6 [g / 100 g of water]).

[0128] Furthermore, among the glycol ethers, diethers tend to dissolve or swell the resin in the ink more easily than monoethers, and are therefore more preferred in terms of improving the abrasion resistance of the formed image, whereas monoethers are preferred in terms of providing excellent ink wetting and spreading properties.

[0129] 1.6.4 Alkanolamines Alkanolamines are compounds having a hydroxyl group and an amino group in an alkane skeleton. The number of hydroxyl groups in the molecule of alkanolamines is 1 or more, preferably 1 to 5, and more preferably 2 to 3. The number of carbon atoms in the molecule of alkanolamines is preferably 1 to 20, more preferably 2 to 10, and even more preferably 6 to 9. The number of carbon atoms per alkane skeleton is preferably 1 to 6, and more preferably 2 to 4. The number of amino groups in the molecule of alkanolamines is 1 or more, preferably 1 to 5, and more preferably 1 to 2.

[0130] The alkanolamines are not particularly limited, and examples thereof include ethanolamine (miscible with water), N-methylethanolamine (solubility 100 [g / 100g of water]), N,N-dimethylethanolamine (completely miscible with water), N-ethylethanolamine (miscible with water), N-butylethanolamine (miscible with water), N,N-diethylethanolamine (miscible with water), diethanolamine (solubility 100 [g / 100g of water]), N-methyldiethanolamine (solubility 100 [g / 100g of water]), N-ethyldiethanolamine (miscible with water), N-butyldiethanolamine (miscible with water), N-tert-butyldiethanolamine (completely miscible with water), triethanolamine (TEA, completely miscible with water), isopropanolamine (miscible with water), and N,N-dimethylisopropanolamine (completely miscible with water). completely miscible), N,N-diethylisopropanolamine (miscible with water), diisopropanolamine (solubility 87 [g / 100g water]), triisopropanolamine (TIPA, normal boiling point 301°C, solubility 83 [g / 100g water]), N,N-dimethylpropanolamine (miscible with water), 2-amino-1-propanol (completely miscible with water), 2-amino-2-methyl-1-propanol (completely miscible with water) ), 5-amino-1-pentanol (miscible with water), 2-amino-2-methyl-1,3-propanediol (miscible with water), 2-amino-2-hydroxymethyl-1,3-propanediol (miscible with water), 3-amino-1,2-propanediol (miscible with water), 3-methylamino-1,2-propanediol (completely miscible with water), tripropanolamine, and tributanolamine.

[0131] Among these, triethanolamine (TEA) and triisopropanolamine (TIPA) are preferred, and triisopropanolamine (TIPA) is more preferred.

[0132] The normal boiling point of the alkanolamines is preferably 280° C. or higher, more preferably 290° C. or higher, and even more preferably 300° C. or higher. Although not limited thereto, the temperature is preferably 350°C or lower, more preferably 330°C or lower, and even more preferably 310°C or lower.

[0133] The inkjet ink composition according to this embodiment preferably contains 0.2% by mass or more of alkanolamines having a normal boiling point of 280°C or higher, relative to the total amount of the ink composition. In this case, the alkanolamines act as pH buffers to stabilize the pH, improving the dispersion stability of pigments and the like and tending to improve clogging recovery. This is also preferred because it makes it easier to adjust the pH of the ink to 8 or higher. The lower limit may be 0.05% by mass or more, or 0.1% by mass or more, and more preferably 0.3% by mass or more. The upper limit is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1.5% by mass or less, particularly preferably 1.0% by mass or less, and even more preferably 0.7% by mass or less.

[0134] 1.7 Antifoaming agents The inkjet ink composition according to this embodiment may contain a defoaming agent. By including a defoaming agent, bubbles generated in the ink composition are eliminated, and better ejection stability tends to be obtained. Note that the surfactant and the defoaming agent are different components.

[0135] The antifoaming agent is not particularly limited, but examples thereof include silicone-based antifoaming agents, polyether-based antifoaming agents, fatty acid ester-based antifoaming agents, and acetylene glycol-based antifoaming agents. Commercially available antifoaming agents include BYK-011, BYK-012, BYK-017, BYK-018, BYK-019, BYK-020, BYK-021, BYK-022, BYK-023, BYK-024, BYK-025, BYK-028, BYK-038, BYK-044, BYK-080A, BYK-094, BYK-1610, BYK-1615, BYK-1650, BYK-1730, and BYK-1770 (all trade names, manufactured by BYK Japan K.K.), Surfynol DF37, DF110D, DF58, DF75, DF220, MD-20, and Envirogem AD01 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.). The antifoaming agent may be used alone or in combination of two or more.

[0136] The content of the antifoaming agent is preferably 0.01 to 1 mass % relative to the total amount of the ink composition, more preferably 0.03 to 0.5 mass %, even more preferably 0.05 to 0.3 mass %, and particularly preferably 0.07 to 0.15 mass %.

[0137] 1.8 Alkaline compounds The inkjet ink composition according to this embodiment may contain an alkaline compound. Examples of alkaline compounds include inorganic alkaline compounds such as hydroxides of alkali metals or alkaline earth metals, and organic alkaline compounds such as amine compounds.

[0138] Examples of inorganic alkaline compounds include hydroxides of alkali metals or alkaline earth metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and calcium hydroxide.

[0139] Whether the ink contains an inorganic alkali compound or not, the content of the inorganic alkali compound is preferably 0.06% by mass or less relative to the total amount of the ink composition. In other words, it is preferable that the content does not exceed 0.06% by mass. Furthermore, the content is more preferably 0.04% by mass or less, even more preferably 0.02% by mass or less, particularly preferably 0.01% by mass or less, and it is also possible for the ink to be absent. When the content is within the above range, it is easier to adjust the pH of the ink to the aforementioned range, and clogging recovery and abrasion resistance are more excellent, which is preferable.

[0140] Examples of the amine compound include primary amines, secondary amines, and tertiary amines. Ammonia is also included in the amine compound. Although not particularly limited, the molecular weight is preferably 500 or less, more preferably 300 or less, even more preferably 250 or less, and particularly preferably 200 or less. Although not particularly limited, the lower limit of the molecular weight is preferably 40 or more, more preferably 80 or more, and even more preferably 120 or more.

[0141] Examples of primary amines include methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, and tert-butylamine.

[0142] Examples of secondary amines include N,N-dimethylamine, N,N-diethylamine, N,N-di-n-propylamine, N,N-diisopropylamine, N,N-di-n-butylamine, N,N-diisobutylamine, and N,N-di-sec-butylamine.

[0143] Examples of tertiary amines include trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, triethanolamine, triisopropanolamine, and trishydroxymethylaminomethane.

[0144] The water-soluble low-molecular-weight organic compounds and poorly water-soluble low-molecular-weight organic compounds such as the alkanolamines described above, which exhibit alkaline properties when dissolved in aqueous solution, may also be a type of organic alkaline compound.

[0145] As the alkaline compound, an amine compound is preferred, and alkanolamines are particularly preferred. Alkanolamines also function as pH buffers, stabilizing the pH of the ink and tending to improve the dispersion stability of pigments, etc. Furthermore, they are preferred because they have excellent clogging recovery properties and abrasion resistance.

[0146] 1.9 Other ingredients The inkjet ink composition according to this embodiment may contain various additives, such as wax, a chelating agent, an anti-rust agent, an anti-fungal agent, an antioxidant, an anti-reducing agent, and an evaporation accelerator, as needed.

[0147] 1.10 Physical Properties The inkjet ink composition according to this embodiment has a pH of 8-10. The pigments and resin particles used in the ink-jet ink composition are preferably dispersed in water using an alkali-soluble polymer dispersant or surfactant. When the ink pH is alkaline, the dispersant's terminal groups are ionized and reach chemical equilibrium, resulting in stronger electrical repulsion and less aggregation. For this reason, raising the ink pH could be considered as a way to improve clogging recovery. However, in aqueous inks containing poorly water-soluble low-molecular-weight organic compounds, this would actually worsen clogging recovery because the solubility of the poorly water-soluble low-molecular-weight organic compounds would decrease and they would be more likely to form foreign matter. Therefore, the ink pH is set to 10 or less. Furthermore, silicone-based surfactants tend to hydrolyze at high pH levels, and prolonged storage can cause the silicone-based surfactant to decompose, resulting in the ink's insufficient wetting and spreading properties. Therefore, the ink pH is set to 10 or less. An ink pH of 10 or less can suppress hydrolysis of the silicone-based surfactant. On the other hand, if the ink pH is too neutral, counter ions will re-adsorb to the terminal groups, weakening the electrical repulsion and making it easier for the resin and pigment to aggregate. Therefore, the ink pH should be 8 or higher.

[0148] The inkjet ink composition according to this embodiment has a pH of 8 or higher, preferably 8.1 or higher, more preferably 8.2 or higher, even more preferably 8.3 or higher, and particularly preferably 8.4 or higher. The inkjet ink composition according to this embodiment has a pH of 10 or less, preferably 9.5 or less, more preferably 9.0 or less, even more preferably 8.8 or less, and particularly preferably 8.5 or less. When the pH is within the above range, the clogging recovery property tends to be better.

[0149] 1.11 Purpose The inkjet ink composition according to this embodiment is used for recording on a low-absorbency recording medium or a non-absorbency recording medium.

[0150] "Low-absorbency recording medium or non-absorbency recording medium" refers to a recording medium that does not absorb liquid at all or absorbs very little. Quantitatively, "low-absorbency recording medium or non-absorbency recording medium" refers to a recording medium that "is capable of absorbing liquid within 30 msec from the start of contact in the Bristow method." 1 / 2 Water absorption up to 10mL / m 2 This refers to the recording medium described below. The Bristow method is the most widely used method for measuring liquid absorption in a short period of time, and is also adopted by the Japan Pulp and Paper Technical Association (JAPAN TAPPI). Details of the test method are described in Standard No. 51 "Paper and paperboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper and Pulp Test Methods 2000 Edition."

[0151] The low-absorbency recording medium is not particularly limited, but examples thereof include coated paper having a coating layer on the surface for receiving ink. Examples of coated paper include, but are not particularly limited to, printing paper such as art paper, coated paper, and matte paper. The coating layer is difficult to absorb ink, and examples thereof include those coated with particles of inorganic compounds or the like together with a binder.

[0152] The non-absorbent recording medium is not particularly limited, but examples thereof include recording media made of plastic, glass, metal, ceramics, and the like.

[0153] When the recording medium is plastic, it can be, for example, a plastic film. Examples of such plastic films include polyester film, polyurethane film, polycarbonate film, polyphenylene sulfide film, polyimide film, and polyamideimide film. Other examples include polyolefins such as polyethylene and polypropylene, and polyvinyl chloride. Biomass-derived plastic films are also included, such as PLA, PBS, PHA, bio-PE, bio-PP, and bio-PET.

[0154] It may also be a film made of plastic, or a substrate such as paper coated with plastic, or a substrate such as paper with a plastic film adhered thereto.

[0155] When the recording medium is metallic, it may be a substrate made of a metal such as iron, silver, copper, or aluminum, or a substrate made of a non-metallic material such as plastic on which any of these metals have been vapor-deposited. In other words, it is sufficient if the recording surface is made of metal.

[0156] The recording medium may be a light-transmitting recording medium such as colorless transparent, semi-transparent, or colored transparent. Alternatively, it may be a light-non-transmitting recording medium such as a chromatic opaque or achromatic opaque. Furthermore, the recording medium may be a sheet, a spherical object, a rectangular object, or a paper container having a three-dimensional shape.

[0157] Among these recording media, non-absorbent recording media are preferred from the viewpoint of being able to enjoy the effects of the present invention more effectively, and recording media with a printing surface made of polyvinyl chloride are particularly preferred. In other words, such recording media are particularly prone to problems with image quality because the ink is less likely to wet and spread on them, but the inkjet ink composition according to this embodiment tends to provide excellent image quality even on such recording media, and also to provide excellent recovery properties from clogging of the inkjet head.

[0158] 2. Recording method A recording method according to one embodiment of the present invention comprises a step of ejecting the inkjet ink composition from an inkjet head and depositing it on a recording medium, which is a low-absorbency recording medium or a non-absorbency recording medium.

[0159] According to the recording method of this embodiment, by using the inkjet ink composition described above, it is possible to obtain excellent image quality and also to achieve excellent recovery from clogging of the inkjet head.

[0160] Each step in the recording method according to this embodiment will be described below.

[0161] 2.1 Ink deposition process The recording method according to this embodiment includes a step of ejecting the inkjet ink composition from an inkjet head and depositing it onto a recording medium, which is a low-absorbency recording medium or a non-absorbency recording medium (ink depositing step).

[0162] The low-absorbency recording medium or the non-absorbency recording medium has been described above, so a detailed description thereof will be omitted.

[0163] In the ink application step, the amount of ink composition applied per unit area of ​​the recording medium in the region where the ink is applied is preferably 15 mg / inch 2 It is preferably 13 mg / inch or less. 2 More preferably, it is 12 mg / inch or less. 2 The following is the result. Even when the amount of ink composition deposited is within the above range, the ink tends to fill the recording medium well, and excellent image quality tends to be obtained. Furthermore, it is also good and preferable to set the amount of ink composition deposited per unit area of ​​the recording medium in the region where the amount of ink deposited is greatest, i.e., the maximum amount of ink deposited, within the above range.

[0164] In the ink application step, the surface temperature of the recording medium when the ink-jet ink composition is applied to the recording medium is preferably 55° C. or less. In this case, the ink application step may be performed without heating the recording medium, or may be performed with heating. That is, even when heating is performed, it is preferable to heat the recording medium so that the surface temperature is 55° C. or less.

[0165] The upper limit of the surface temperature of the recording medium during ink adhesion is preferably 55°C or lower, more preferably 50°C or lower, even more preferably 45°C or lower, particularly preferably 40°C or lower, even more particularly preferably 35°C or lower, and especially preferably 28°C or lower. On the other hand, the lower limit is preferably 20°C or higher, more preferably 23°C or higher, and particularly preferably 25°C or higher. Furthermore, 28°C or higher is preferable, more preferably 35°C or higher, and even more preferably 40°C or higher.

[0166] 2.2 Primary drying process The recording method according to this embodiment may include a primary drying step of drying the inkjet ink composition adhered to the recording medium.

[0167] In a recording method, including a primary drying process is preferable because it allows the ink to dry quickly on the recording medium, thereby improving image quality. On the other hand, the primary drying process dries the ink quickly, making it difficult for the ink to wet and spread on the recording medium. In other words, recording methods that include a primary drying process are prone to problems with image quality. However, the recording method according to this embodiment tends to be able to obtain excellent image quality and also provide excellent recovery from clogging of the inkjet head, even in such cases.

[0168] The primary drying process is a process for drying ink adhered to a recording medium at an early stage. The primary drying process is a process for drying at least a portion of the ink solvent component of the ink adhered to the recording medium to at least an extent that reduces the ink flow. In the primary drying process, it is preferable that the ink droplets that land on the recording medium start to dry within 0.5 seconds at the latest after the ink droplets land on the recording medium.

[0169] Examples of the means for the primary drying step include an air blowing method, which is a method based on blowing air at room temperature (room temperature air) or heated air (hot air) to the recording medium using a fan or the like, an IR heater, a microwave radiation method, a heat transfer method based on heating the recording medium using a platen heater or the like, and a method combining these. Here, the primary drying step in this embodiment is not particularly limited as long as it can improve the drying properties of the ink, and does not necessarily have to involve heating. Therefore, in the primary drying step in this embodiment, a method based on blowing air at room temperature may be used alone. It is more preferable that the primary drying step be a method that involves heating.

[0170] When drying by air blowing is performed in the primary drying step, the air blowing speed is preferably 0.5 to 15 m / s, more preferably 0.5 to 10 m / s, even more preferably 1 to 5 m / s, and particularly preferably 2 to 3 m / s, which is the air speed near the surface of the recording medium. The temperature of the blown air is preferably 55° C. or lower, and preferably 10° C. or higher. It is more preferably 15 to 50° C., and more preferably 20 to 49° C. It is further preferably 23 to 40° C., more preferably 25 to 35° C., and even more preferably 25 to 28° C. The temperature of the blown air may be room temperature.

[0171] The surface temperature of the recording medium in the primary drying step may be within the range of the temperature described above as the surface temperature of the recording medium in the ink application step, and is therefore preferably 55°C or less, and more preferably within the above-mentioned surface temperature range. When the drying temperature in the primary drying step is within the above range, the drying of the ink inside the inkjet head can be reduced, and therefore clogging recovery tends to be more excellent.

[0172] If heating is involved in the primary drying step, the ink may be applied to a heated recording medium, or the recording medium may be heated immediately after application. Preferably, the primary drying step begins within 0.5 seconds at the latest after the ink droplets land on the recording medium. When heating is performed in the primary drying step, the heating may be performed at least either before the ink application step, simultaneously with the application, or shortly after the application, and preferably simultaneously. The ink application step can be performed in such a heating order.

[0173] The surface temperature of the recording medium in the primary drying step is the surface temperature of the recording medium at the time of ink application when ink is applied to a recording medium that has undergone the primary drying step, and is the surface temperature of the recording medium at the time of the primary drying step when the primary drying step is performed soon after the ink is applied. It is also the maximum temperature due to the primary drying step during the primary drying step. The surface temperature of the recording medium in the primary drying step in these cases is within the range of the surface temperature of the recording medium at the time of ink application described above. It is preferable. Furthermore, the surface temperature of the recording medium when no heating is performed in the primary drying step is the surface temperature of the recording medium when the ink is attached.

[0174] 2.3 Post-heating process The recording method according to this embodiment may include a post-heating step of heating the recording medium after the ink deposition step.

[0175] The inkjet ink composition used in the recording method according to this embodiment contains a poorly water-soluble low-molecular-weight organic compound, and therefore the ink drying property after the ink application step is better than when the ink does not contain a poorly water-soluble low-molecular-weight organic compound. Furthermore, by including a post-heating step in the recording method according to this embodiment, the drying property can be further improved, which is preferable as it tends to result in a recorded product with better abrasion resistance.

[0176] The post-heating step is a heating step that heats the ink sufficiently to complete the recording and make the recorded matter usable. The post-heating step is a heating step that thoroughly dries the ink solvent component and heats the resin particles contained in the ink to flatten the ink coating. The post-heating step is preferably started more than 0.5 seconds after the ink is applied to the recording medium. For example, it is preferable to start heating a certain recording area of ​​the recording medium more than 0.5 seconds after all ink application to that area is complete. Furthermore, it is preferable that the temperature preferred in the primary drying step is different from the temperature preferred in the post-heating step.

[0177] For example, when an inkjet recording apparatus is used, heating of the recording medium in the post-heating step can be performed using an appropriate heating means. Furthermore, the heating means is not limited to those provided in the inkjet recording apparatus, and can be performed using any appropriate heating means. In this case, the surface temperature of the recording medium is preferably 60°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, and particularly preferably 85°C or higher. Furthermore, the surface temperature of the recording medium heated in the post-heating step is preferably 120°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and particularly preferably 95°C or lower. According to the recording method of this embodiment, even at a surface temperature of the recording medium within the above range, the ink tends to be sufficiently dried and a recorded product with excellent abrasion resistance can be obtained.

[0178] 2.4 Inkjet recording device An example of an inkjet recording apparatus that can be preferably applied to the recording method according to this embodiment will be described with reference to the drawings.

[0179] FIG. 1 is a schematic cross-sectional view showing an inkjet recording apparatus. FIG. 2 is a perspective view showing an example of the configuration of the periphery of the carriage of the inkjet recording apparatus 1 of FIG. 1. As shown in FIGS. 1 and 2, the inkjet recording apparatus 1 includes an inkjet head 2, an IR heater 3, a platen heater 4, a heating heater 5, a cooling fan 6, a preheater 7, a ventilation fan 8, a carriage 9, a platen 11, a carriage movement mechanism 13, a transport means 14, and a control unit CONT. The operation of the entire inkjet recording apparatus 1 is controlled by the control unit CONT shown in FIG. 2.

[0180] The inkjet head 2 is configured to perform recording on a recording medium M by ejecting and depositing an inkjet ink composition from the nozzles of the inkjet head 2. The inkjet head 2 shown in Figs. 1 and 2 is a serial type inkjet head, which scans the recording medium M relatively in the main scanning direction multiple times to deposit ink onto the recording medium M. The inkjet head 2 is mounted on a carriage 9 shown in Fig. 2. The inkjet head 2 is scanned multiple times in the main scanning direction relative to the recording medium M by the operation of a carriage movement mechanism 13 that moves the carriage 9 in the medium width direction of the recording medium M. The medium width direction is the main scanning direction of the inkjet head 2. Scanning in the main scanning direction is also called main scanning.

[0181] Here, the main scanning direction is the direction in which the carriage 9 carrying the inkjet head 2 moves. In FIG. 1, this is the direction intersecting the sub-scanning direction, which is the transport direction of the recording medium M, indicated by the arrow SS. In FIG. 2, the width direction of the recording medium M, i.e., the direction indicated by S1-S2, is the main scanning direction MS, and the direction indicated by T1→T2 is the sub-scanning direction SS. Note that scanning is performed in either the main scanning direction, i.e., the direction indicated by the arrow S1 or the arrow S2, in one scan. Then, recording is performed on the recording medium M by repeating the main scanning of the inkjet head 2 and the sub-scanning, which is the transport direction of the recording medium M, multiple times.

[0182] The cartridges 12 that supply ink to the inkjet head 2 include a plurality of independent cartridges. The cartridges 12 are detachably mounted on a carriage 9 that mounts the inkjet head 2. Each of the plurality of cartridges can be filled with a different type of inkjet ink composition, and the inkjet ink composition is supplied from the cartridges 12 to each nozzle. Note that while FIGS. 1 and 2 show an example in which the cartridge 12 is mounted on the carriage 9, this is not limiting, and the cartridge 12 may be provided at a location other than the carriage 9 and may supply ink to each nozzle via a supply pipe (not shown).

[0183] A conventionally known method can be used for ejection from the inkjet head 2. Here, a method of ejecting droplets using the vibration of a piezoelectric element, that is, an ejection method of forming ink droplets by mechanical deformation of an electrostrictive element, is used.

[0184] The inkjet recording device 1 may be equipped with a primary drying mechanism that dries the recording medium M when ink is ejected from the inkjet head 2 and deposited on the recording medium. The primary drying mechanism may be of a conduction type, an air blowing type, or a radiation type. The conduction type transfers heat to the recording medium from a member in contact with the recording medium. For example, a platen heater is used. The air blowing type dries the ink by blowing room temperature or warm air onto the recording medium. For example, a fan is used. The radiation type heats the recording medium by radiating heat-generating radiation onto the recording medium. For example, IR radiation is used. Although not shown, a heater similar to the platen heater 4 may be provided immediately downstream of the platen heater 4 in the SS direction. These primary drying mechanisms may be used alone or in combination. For example, the primary drying mechanism may include an IR heater 3 and a platen heater 4.

[0185] If the IR heater 3 is used, the recording medium M can be radiatively heated by radiating infrared rays from the inkjet head 2 side. This makes it easier for the inkjet head 2 to be heated at the same time, but compared to heating from the back side of the recording medium M using a platen heater 4 or the like, the temperature can be increased without being affected by the thickness of the recording medium M. Various types of fans (for example, ventilation fan 8) may be provided to blow warm air or air at the same temperature as the environment onto the recording medium M to dry the ink on the recording medium M.

[0186] The platen heater 4 is capable of heating the recording medium M via a platen 11 at a position facing the inkjet head 2. The platen heater 4 is capable of conducting heat to the recording medium M, and is used as needed in the inkjet recording method.

[0187] The inkjet recording apparatus 1 may also include a preheater 7 that preheats the recording medium M before the ink is applied to the recording medium M.

[0188] A post-heating mechanism may be provided that heats the recording medium after the ink application step to dry and fix the ink.

[0189] The heater 5 used in the post-heating mechanism dries and solidifies the ink attached to the recording medium M. When the heater 5 heats the recording medium M on which an image has been recorded, the moisture contained in the ink evaporates and dissipates more quickly, and an ink film is formed by the resin particles contained in the ink. In this way, the ink film is firmly fixed or adhered to the recording medium M, providing excellent film-forming properties, and an excellent, high-quality image can be obtained in a short time.

[0190] The inkjet recording apparatus 1 may have a cooling fan 6. After the ink recorded on the recording medium M has dried, the ink on the recording medium M is cooled by the cooling fan 6, thereby forming an ink coating film on the recording medium M with good adhesion.

[0191] Below the carriage 9, there are provided a platen 11 that supports the recording medium M, a carriage movement mechanism 13 that moves the carriage 9 relative to the recording medium M, and a conveying means 14 that is a roller that conveys the recording medium M in the sub-scanning direction. The operations of the carriage movement mechanism 13 and the conveying means 14 are controlled by a control unit CONT.

[0192] 3. 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.

[0193] 3.1 Preparation of Inkjet Ink Composition The components were placed in a container so as to obtain the compositions shown in Tables 1 and 2, and mixed and stirred for 2 hours using a magnetic stirrer. The mixture was then filtered through a membrane filter with a pore size of 5 μm to obtain inkjet ink compositions according to the examples and comparative examples. The values ​​in the tables for the pigment and resin particles indicate their solid content. Pure water was added so that the total mass of the composition was 100% by mass. A pigment dispersion liquid prepared in advance using the following procedure was used as the pigment.

[0194] [Preparation of pigment dispersion] First, 50 g of methyl ethyl ketone (MEK) was added to a flask equipped with a dropping funnel, a nitrogen inlet tube, a reflux condenser, a thermometer, and a stirrer, and the mixture was heated to 75°C while bubbling with nitrogen. A mixture of monomers (80 g of butyl methacrylate, 50 g of methyl methacrylate, 15 g of styrene, and 20 g of methacrylic acid), 50 g of MEK, and 500 mg of a polymerization initiator (azobisisobutyronitrile / AIBN) was added dropwise from the dropping funnel over 3 hours. After the dropwise addition, the mixture was heated under reflux for an additional 6 hours. After cooling, the evaporated amount of MEK was added, yielding a resin solution (resin solids content 50% by mass, acid value 79 mg / KOH, Tg 65°C). To 20 g of this solution, a predetermined amount of 20% by weight aqueous sodium hydroxide solution was added as a neutralizing agent to 100% neutralize the salt-forming groups. While stirring, 50 g of pigment (CI Pigment Blue 15:3) was gradually added, followed by kneading for 2 hours using a bead mill. 200 g of ion-exchanged water was added to the resulting kneaded mixture, which was then stirred and heated under reduced pressure to distill off the MEK. The concentration was then adjusted with pure water to obtain a pigment dispersion (pigment solids 20% by weight, resin solids 5% by weight).

[0195] The components shown in Tables 1 and 2 will now be explained in more detail. Joncryl 631: BASF product name Hi-Tech E-6500: Toho Chemical Co., Ltd. product name, polyethylene wax emulsion 1,2HD: 1,2-hexanediol, miscible with water 1,2PD: 1,2-pentanediol, miscible with water 1,2BD: 1,2-butanediol, miscible with water PG: Propylene glycol, miscible with water TIPA: Triisopropanolamine, miscible with water TEA: Triethanolamine, miscible with water BEPG: 2-butyl-2-ethyl-1,3-propanediol (butyl ethyl propanediol), normal boiling point 264°C, melting point 41°C, solubility 0.9 [g / 100g water] 1,2OD: 1,2-octanediol, normal boiling point 267°C, melting point 28°C, solubility 0.3 [g / 100g water] EHDG: Diethylene glycol mono 2-ethylhexyl ether (2-ethylhexyl diglycol), normal boiling point 277°C, melting point -82°C, solubility 0.5 [g / 100g water] DBDG: Diethylene glycol dibutyl ether, normal boiling point 256°C, melting point -60°C, solubility 0.3 [g / 100g water] NOP: n-(n-octyl)-2-pyrrolidone, normal boiling point 306°C, melting point -23°C, liquid (25°C), cyclic amides, solubility 0.1 [g / 100g water] BYK-3420: Product name manufactured by BYK Japan Co., Ltd. SAG503A: Product name manufactured by Nissin Chemical Industry Co., Ltd. TEGO Wet 270: Evonik product name Olfine E1010: Product name manufactured by Nissin Chemical Industry Co., Ltd. Olfine EXP.4123: Product name manufactured by Nissin Chemical Industry Co., Ltd. Olfine E1020: Product name manufactured by Nissin Chemical Industry Co., Ltd. Surfynol 104PG-50: Product name manufactured by Nissin Chemical Industry Co., Ltd. Surfynol DF110D: Product name manufactured by Nissin Chemical Industry Co., Ltd.

[0196] 3.2 Printing conditions The printing conditions for the evaluation tests described below were as follows. Printing machine: "SC-R5050", manufactured by Seiko Epson Corporation Resolution: 1200 x 1200 dpi Number of scans: 9 Platen heating temperature: 45℃ ·Secondary drying temperature: 80℃ Recording medium: "Orajet 3165G-010", manufactured by Orafor Japan, PVC film Platen gap: 1.7mm

[0197] The "platen heating temperature" refers to the surface temperature of the recording medium in the platen area facing the inkjet head during recording. The "secondary drying temperature" refers to the surface temperature of the recording medium heated by the secondary heater located downstream of the inkjet head. Heat drying at the secondary drying temperature was performed for approximately 3 minutes.

[0198] 3.3 Evaluation Test 3.3.1 Image quality The inkjet ink composition obtained above was filled into SC-R5050, and a solid pattern was printed on a recording medium under the above printing conditions. The ink deposition amount was 10 to 14 mg / inch. 2 Between 1 mg / inch 2 The printed matter was visually observed and judged according to the following evaluation criteria: When the surface of the recording medium was filled with ink and the base of the recording medium was not visible, the filling was judged to be good. (Evaluation criteria) AA: Ink deposition amount 12 mg / inch 2 Fills well with A: Ink deposition amount 13 mg / inch 2 Fills well with B: Ink deposition amount 14 mg / inch 2 Fills well with C: Ink deposition amount 14 mg / inch 2 But it won't fill up

[0199] 3.3.2 Clogging recovery The inkjet ink composition obtained above was filled into an SC-R5050, and the nozzle surface was struck with a water-moistened Bemcot to intentionally cause nozzle clogs. Under this condition, the printer was left idle for two hours at 40°C and 15% humidity. After recording under the above printing conditions, cleaning was performed three times, and the number of unrecovered nozzles was counted. Each cleaning involved discharging 1 g of ink from the nozzle group. The nozzle group consisted of 800 nozzles. (Evaluation criteria) AA: Nozzle non-ejection less than 1% A: Nozzle non-ejection rate: 1% to less than 2% B: Nozzle non-discharge rate: 2% to less than 4% C: Nozzle non-ejection rate 4% or more

[0200] 3.3.3 Scratch resistance of printed matter The inkjet ink composition obtained above was filled into SC-R5050, and a solid pattern (color ink deposition amount 12 mg / inch) was printed on a recording medium. 2 ) was printed under the above printing conditions. After leaving it at room temperature for 30 minutes, the ink-adhered area was cut into a 25 x 150 mm rectangle and rubbed 100 times with a water-moistened plain woven cloth in a Gakushin abrasion resistance tester (load 500 g). The degree of ink peeling was visually evaluated and rated according to the following criteria. (Evaluation criteria) AA: No peeling A: Less than 20% of the evaluation area is peeled off B: Less than 50% of the evaluation area is peeled off C: Peeling of more than 50% of the evaluation area

[0201] 3.4 Evaluation results The evaluation results are shown in Table 3. The evaluation results shown in Table 3 reveal that water-based inkjet ink compositions used for recording on low-absorbency recording media or non-absorbency recording media, which contain a pigment, resin particles, a surfactant, and a poorly water-soluble low-molecular-weight organic compound that is either an alkanediol or a glycol ether and has a solubility in water of 10 g / 100 g of water or less, wherein the surfactant includes a silicone-based surfactant and an acetylene glycol-based surfactant having an HLB value of 9 to 14, and which have a pH of 8 to 10, not only produce excellent image quality but also have excellent recovery properties from clogging in inkjet heads.

[0202] In contrast, the inkjet ink compositions according to the comparative examples, which did not satisfy the above requirements, were inferior in at least one of image quality and clogging recovery properties.

[0203] Although not shown in the table, the evaluations were carried out in the same manner as in Example 1, except that the recording medium was changed to a PET film (product name "Window-Grip (registered trademark) Ultra Clear" manufactured by Neschen). The evaluation results were B for image quality, A for clogging recovery, and A for abrasion resistance. This demonstrates that excellent results can also be obtained when printing on PET film. Furthermore, when recording was carried out on plain paper as a recording medium other than a low-absorbency or non-absorbency recording medium, the ink was absorbed and spread into the recording medium, so there was no problem with poor filling, but the recorded product had poor abrasion resistance and water resistance.

[0204] The following can be derived from the above-described embodiment.

[0205] One embodiment of the inkjet ink composition comprises: 1. A water-based inkjet ink composition comprising: It is used for recording on a recording medium that is a low-absorbency recording medium or a non-absorbency recording medium, The ink contains a pigment, resin particles, a surfactant, and a poorly water-soluble low-molecular-weight organic compound that is either an alkanediol or a glycol ether and has a solubility in water of 10 g / 100 g of water or less, The surfactant includes a silicone surfactant and an acetylene glycol surfactant having an HLB value of 9 to 14, The pH is 8 to 10.

[0206] In one embodiment of the inkjet ink composition, The inkjet ink composition may contain 1 to 5 mass % of an alkanediol having 4 to 6 carbon atoms as a water-soluble low-molecular organic compound, based on the total mass of the ink composition.

[0207] In any of the above ink-jet ink compositions, The content of the poorly water-soluble low-molecular-weight organic compound may be 0.1 to 2% by mass with respect to the total amount of the ink composition.

[0208] In any of the above ink-jet ink compositions, The inkjet ink composition may contain the poorly water-soluble low-molecular-weight organic compound, which is an alkanediol.

[0209] In any of the above ink-jet ink compositions, The total content of the acetylene glycol surfactant having an HLB value of 9 to 14 and the silicone surfactant may be 0.1 to 1% by mass with respect to the total amount of the ink composition.

[0210] In any of the above ink-jet ink compositions, The silicone surfactant may have a cloud point of 40° C. or higher.

[0211] In any of the above ink-jet ink compositions, The inkjet ink composition may contain 0.2% by mass or more of alkanolamines having a normal boiling point of 280° C. or higher, based on the total amount of the ink composition.

[0212] In any of the above ink-jet ink compositions, The printing surface of the recording medium may be made of polyvinyl chloride.

[0213] One aspect of the recording method is The method includes a step of ejecting the ink-jet ink composition of any of the above aspects from an ink-jet head and depositing it on a recording medium, which is a low-absorbency recording medium or a non-absorbency recording medium.

[0214] 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]

[0215] 1... Inkjet recording device, 2... Inkjet head, 3... IR heater, 4... Latin heater, 5...heating heater, 6...cooling fan, 7...preheater, 8...ventilation fan, 9...carriage, 11...platen, 12...cartridge, 13...carriage moving mechanism, 14...conveying means, CONT...control unit, MS...main scanning direction, SS...sub-scanning direction, M...recording medium

Claims

1. 1. A water-based inkjet ink composition comprising: It is used for recording on a recording medium that is a low-absorbency recording medium or a non-absorbency recording medium, The ink contains a pigment, resin particles, a surfactant, and a poorly water-soluble low-molecular-weight organic compound that is either an alkanediol or a glycol ether and has a solubility in water of 10 g / 100 g of water or less, the surfactant includes a silicone surfactant and an acetylene glycol surfactant having an HLB value of 9 to 14; An ink-jet ink composition having a pH of 8 to 10.

2. 2. The ink-jet ink composition according to claim 1, wherein the ink-jet ink composition contains, as the water-soluble low-molecular organic compound, an alkanediol having 4 to 6 carbon atoms in an amount of 1 to 5% by mass relative to the total amount of the ink composition.

3. 2. The ink-jet ink composition according to claim 1, wherein the content of the poorly water-soluble low-molecular-weight organic compound is 0.1 to 2% by mass relative to the total amount of the ink composition.

4. The ink-jet ink composition according to claim 1 , wherein the poorly water-soluble low-molecular-weight organic compound is an alkanediol.

5. 2. The ink-jet ink composition according to claim 1, wherein the total content of the acetylene glycol surfactant having an HLB value of 9 to 14 and the silicone surfactant is 0.1 to 1% by mass with respect to the total amount of the ink composition.

6. The ink-jet ink composition of claim 1 , wherein the silicone surfactant has a cloud point of 40° C. or higher.

7. The ink-jet ink composition according to claim 1, wherein the ink-jet ink composition contains 0.2% by mass or more of alkanolamines having a normal boiling point of 280° C. or higher, based on the total amount of the ink composition.

8. The ink-jet ink composition of claim 1 , wherein the recording medium has a printing surface made of polyvinyl chloride.

9. A recording method comprising a step of ejecting the ink-jet ink composition according to claim 1 from an ink-jet head and depositing it on a recording medium which is a low-absorbency recording medium or a non-absorbency recording medium.

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