Inkjet ink composition and recording method

Abstract

To provide an aqueous inkjet ink composition which is excellent in scratch resistance and an image quality (aggregation unevenness), and can excellently reduce impact displacement, in recording on a low absorptive or non-absorptive recording medium.SOLUTION: An inkjet ink composition is aqueous ink which contains a pigment and a resin, and is used in recording on a low absorptive recording medium or non-absorptive recording medium, contains a water-soluble low molecular organic compound that has a melting point of 30°C or higher, and is any one of amides, sulfur-containing materials, and cyclic ethers in a content of 10 mass% or less with respect to the total mass of the ink composition, and contains an organic solvent that is diols having a melting point of 25°C or lower in a content larger than the content of the low molecular organic compound.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002]

[0003] An inkjet recording method is known in which minute ink droplets of an inkjet ink composition (hereinafter also referred to as "ink composition" or "ink") are ejected from nozzles of an inkjet head of an inkjet recording apparatus to record an image on a recording medium. In recent years, inkjet recording methods have come to be used not only for recording images on recording media with excellent ink absorbency, such as plain paper, but also for recording images on low-absorbency recording media with low ink absorbency, such as art paper and coated paper, and non-absorbency recording media that hardly absorb ink, such as plastic film. Water-based aqueous inkjet inks (hereinafter also referred to as "aqueous inks") have also come to be used for recording images on such low-absorbency recording media and non-absorbency recording media.

[0003] Furthermore, because aqueous inks tend to have poor fixability and abrasion resistance on low-absorbency or non-absorbency recording media, there is a technique for incorporating nitrogen-containing solvents such as 2-pyrrolidone into the ink (see, for example, Patent Document 1). Such nitrogen-containing solvents have the ability to dissolve resins in the ink and the recording media, thereby swelling and dissolving them, and therefore contribute to improving abrasion resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-134801 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when using water-based ink to record on low-absorbency or non-absorbency recording media, not only is there the problem that the abrasion resistance is likely to be poor, but also the ink is difficult to absorb into the recording medium, so when adjacent ink droplets (dots) that land on the recording medium come into contact, the dots gather together, resulting in a decrease in image quality (agglomeration unevenness). Furthermore, when attempting to improve both abrasion resistance and image quality (agglomeration unevenness), the ink ejection characteristics are likely to change, resulting in the problem of ink droplet landing position deviation (landing deviation).

[0006] That is, when recording on a low-absorbency or non-absorbency recording medium using a water-based ink, it has not been possible to achieve excellent abrasion resistance and image quality (aggregation unevenness) while also being able to significantly reduce impact deviation. [Means for solving the problem]

[0007] One embodiment of the inkjet ink composition according to the present invention comprises: Contains a pigment and a resin, A water-based ink for use in recording on a low-absorbency recording medium or a non-absorbency recording medium, the ink composition contains a water-soluble low-molecular-weight organic compound having a melting point of 30°C or higher and which is any one of an amide, a sulfur-containing compound, or a cyclic ether in an amount of 10% by mass or less relative to the total mass of the ink composition; The organic solvent is a diol having a melting point of 25° C. or less, and the content of the organic solvent is greater than the content of the low-molecular organic compound.

[0008] 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 onto a recording medium, wherein the recording medium is a low-absorbency recording medium or a non-absorbency recording medium. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an example of an inkjet recording apparatus used in a recording method according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of the carriage and its surroundings in an example of an inkjet printing apparatus used in the printing method of the embodiment. [Figure 3] FIG. 1 is a block diagram of an example of an inkjet printing apparatus used in a printing method according to an embodiment. [Figure 4] 4 is a flowchart showing an example of processing performed when printing is performed by an inkjet printing apparatus used in a printing method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described. The embodiments described below are examples of the present invention. The present invention is not limited to the following embodiments, and includes various modified forms that are implemented within the scope of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

[0011] 1. Inkjet ink composition An inkjet ink composition according to one embodiment of the present invention comprises: Contains a pigment and a resin, A water-based ink for use in recording on a low-absorbency recording medium or a non-absorbency recording medium, the ink composition contains a water-soluble low-molecular-weight organic compound having a melting point of 30°C or higher and which is any one of an amide, a sulfur-containing compound, or a cyclic ether in an amount of 10% by mass or less relative to the total mass of the ink composition; The organic solvent is a diol having a melting point of 25° C. or less, and the content of the organic solvent is greater than the content of the low-molecular organic compound.

[0012] The inkjet ink composition according to this embodiment can provide excellent abrasion resistance and image quality (aggregation unevenness) when recording on a low-absorbency or non-absorbency recording medium, and can also effectively reduce landing deviation.

[0013] When recording on a low-absorbency or non-absorbency recording medium using a water-based ink, the ink is difficult to absorb into the recording medium, so when adjacent ink droplets (dots) that have landed on the recording medium come into contact, the dots gather together, resulting in a decrease in image quality (agglomeration unevenness).To address this problem, a technique has been known in the past that uses a treatment liquid containing an aggregating agent that aggregates the ink components, but the use of a treatment liquid has drawbacks such as making the ink less abrasion-resistant.

[0014] The present inventors have now discovered that by incorporating into the ink a water-soluble low-molecular-weight organic compound (hereinafter also referred to as a "specific low-molecular-weight organic compound") that has a melting point of 30°C or higher and is either an amide, a sulfur-containing compound, or a cyclic ether, it is possible to significantly improve image quality (agglomeration unevenness) even without the use of a treatment liquid. It is believed that the inclusion of the specific low-molecular-weight organic compound in the ink makes the ink more viscous when it dries, thereby suppressing dot migration and allowing dots to be fixed at an early stage before they gather together. In other words, excellent image quality (agglomeration unevenness) is achieved not by the reaction between the treatment liquid and the ink (pinning effect), but by the pinning effect of the ink itself containing the specific component. Furthermore, the specific low-molecular-weight organic compound also has resin-solubility, which allows it to swell and dissolve resins contained in the ink and low-absorbency or non-absorbency recording media. Therefore, by incorporating the specific low-molecular-weight organic compound into the ink, excellent image quality (agglomeration unevenness) can be achieved. At the same time, excellent abrasion resistance can be obtained.

[0015] On the other hand, when the ink contains a specific low-molecular-weight organic compound, a new problem of misaligned ink droplet landing positions has arisen. We believe this is because ink containing a specific low-molecular-weight organic compound is prone to change in ejection characteristics, making the ejection direction and ejection speed of ink droplets fluctuate when and after ejection from the inkjet head. We believe this is particularly related to the increase in viscosity that accompanies ink drying. Therefore, the present inventors conducted further intensive research and found that by incorporating an organic solvent that is a diol having a melting point of 25°C or less (hereinafter also referred to as "specific diol") in an amount greater than that of the specific low-molecular-weight organic compound, and by keeping the content of the specific low-molecular-weight organic compound at a predetermined amount or less, it is possible to significantly reduce impact deviation and obtain excellent image quality (agglomeration unevenness) and excellent abrasion resistance.

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

[0017] 1.1 Pigments The inkjet ink composition according to this embodiment contains a pigment. Examples of the pigment that can be used include inorganic pigments such as carbon black and titanium white, and organic pigments.

[0018] Examples of inorganic pigments that can be used include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, titanium oxide, zinc oxide, and silica.

[0019] Examples of carbon black include No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No. 2200B manufactured by Mitsubishi Chemical Corporation. Examples of carbon black include Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, and S170, Pretex 35, U, V, and 140U, and Special Black 6, 5, 4A, 4, and 250 manufactured by Degussa. Examples of carbon black include Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, and 700 manufactured by Columbia Carbon Corporation. Examples include Cabot Corporation's Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, and Elftex 12.

[0020] Examples of organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.

[0021] Specific examples of organic pigments that can be used in the ink-jet ink composition include the following:

[0022] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc.; CI Vat Blue 4, 60, etc., and preferably, one or a mixture of two or more selected from the group consisting of CI Pigment Blue 15:3, 15:4, and 60 can be exemplified.

[0023] Magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), and 48 (Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, CI Pigment Violet 19, etc., and preferably, one or a mixture of two or more selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19 can be exemplified.

[0024] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, and 185. Of these, preferred examples include one or a mixture of two or more selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, 138, 155, and 180.

[0025] Examples of orange pigments include CI Pigment Orange 36 or 43, or a mixture thereof. Examples of green pigments include CI Pigment Green 7 or 36, or a mixture thereof.

[0026] Luster pigments may also be used, and are not particularly limited as long as they can exhibit luster when attached to a medium. Examples include metal particles of one or more alloys (also called metal pigments) selected from the group consisting of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper, and pearl pigments with pearly luster. Representative examples of pearl pigments include pigments with pearly luster or interference luster, such as titanium dioxide-coated mica, fish scale foil, and bismuth oxychloride. The luster pigment may also be surface-treated to suppress reaction with water.

[0027] White pigments may also be used, including, for example, metal oxides, barium sulfate, calcium carbonate, and other metal compounds. Examples of metal oxides include titanium dioxide, zinc oxide, silica, alumina, magnesium oxide, and the like. The white pigment may also be particles having a hollow structure.

[0028] [Pigment Dispersion] 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 both a pigment dispersion and a pigment slurry (low-viscosity aqueous dispersion).

[0029] Examples of pigment dispersions include, but are not limited to, self-dispersed pigments, polymer-dispersed pigments, and pigments coated with polymers.

[0030] (self-dispersing pigment) 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.

[0031] The hydrophilic group is preferably one or more hydrophilic groups selected from the group consisting of -OM, -COOM, -CO-, -SO3M, -SO2M, -SO2NH2, -RSO2M, -PO3HM, -PO3M2, -SON2NHCOR, -NH3, and -NR3.

[0032] 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. Furthermore, the above M and R are each selected independently.

[0033] 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.

[0034] (polymer-dispersed pigment) 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 80°C or lower, more preferably 70°C or lower. When the Tg is 80°C or lower, the fixability of the ink may be improved.

[0035] 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.

[0036] 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.

[0037] In this specification, the term "(meth)acrylic" means at least one of acrylic and methacrylic, and the term "(meth)acrylate" means at least one of acrylate and methacrylate.

[0038] (polymer-coated pigment) Furthermore, among the polymer-dispersed pigments, pigments coated with a polymer, that is, microencapsulated pigments, are preferably used because they tend to provide excellent ink fixation, gloss, and color reproducibility.

[0039] The polymer-coated pigment is obtained by phase inversion emulsification. Specifically, the polymer is dissolved in an organic solvent such as methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone (MEK), or dibutyl ether. The pigment is then added to the resulting solution, followed by the addition of a neutralizer and water, followed by a kneading and dispersion process to prepare an oil-in-water dispersion. The organic solvent is then removed from the resulting dispersion to obtain the polymer-coated pigment as an aqueous dispersion. For the kneading and dispersion process, a ball mill, roll mill, bead mill, high-pressure homogenizer, or high-speed agitator disperser can be used, for example.

[0040] 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.

[0041] 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.

[0042] The pigments may be used alone or in combination of two or more.

[0043] The volume-based average particle size (D50) of the pigment (hereinafter also referred to as the volume average particle size) is preferably 50 to 400 nm, more preferably 50 to 300 nm, even more preferably 75 to 200 nm, particularly preferably 100 to 150 nm, and even more particularly preferably 100 to 120 nm. The volume average particle size can be measured using a particle size distribution analyzer that employs dynamic light scattering as its measurement principle. Examples of particle size distribution analyzers include a particle size distribution analyzer that employs dynamic light scattering as its measurement principle (e.g., the "Nanotrac Wave II EX-150" manufactured by Microtrack Bell Corporation).

[0044] The pigment content can be adjusted appropriately depending on the application, but is preferably from 0.1% to 20.0% by mass, more preferably from 0.2% to 15.0% by mass, and even more preferably from 1.0% to 10.0% by mass, in terms of solid content, relative to the total mass of the ink composition.

[0045] 1.2 Resin The inkjet ink composition according to this embodiment contains a resin. The resin may be water-soluble or water-insoluble. The resin may be dissolved or dispersed in the ink composition. The dissolved resin may be the polymer described above, which is used when dispersing a pigment as a polymer-dispersed pigment. The dispersed resin may be a resin that is poorly soluble or insoluble in the liquid medium of the ink composition, dispersed as resin particles (i.e., in an emulsion or suspension state). Since the resin is preferably in the form of resin particles, it is preferable that the resin contains resin particles, and more preferably the resin is resin particles. Such resin particles function as a fixing resin, improving the adhesion and abrasion resistance of the components of the ink composition adhered to a recording medium. Therefore, when the resin contains resin particles, abrasion resistance can be further improved. When the ink contains a resin, the resin dissolves in the ink adhered to the recording medium due to the specific low-molecular-weight organic compound described below, which facilitates adhesion of the resin to the recording medium, resulting in excellent abrasion resistance.

[0046] Examples of resin particles include resin particles made of urethane resins, acrylic resins, ester resins, fluorene resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, and ethylene vinyl acetate resins. These resin particles are often handled in emulsion form, but may also be in powder form. Furthermore, the resin particles can be used alone or in combination of two or more types.

[0047] Urethane resin is a general term for resins having urethane bonds. In addition to urethane bonds, the urethane resin may be a polyether urethane resin containing ether bonds in the main chain, a polyester urethane resin containing ester bonds in the main chain, or a polycarbonate urethane resin containing carbonate bonds in the main chain. As the urethane-based resin, commercially available products may be used, and may be selected from commercially available products such as Superflex 210, 460, 460s, 840, and E-4000 (trade names, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, and D-6455 (trade names, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Takelac WS-6020, WS-6021, and W-512-A-6 (trade names, manufactured by Mitsui Chemicals Polyurethanes Inc.), Sancure 2710 (trade name, manufactured by Lubrizol), and Parmarin 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] For the resin emulsion made from an acrylic resin, commercially available products may be used, and may be selected from, for example, FK-854, Mowinyl 952B, 718A (trade names, manufactured by Japan Coating Resins Co., Ltd.), Nipol LX852, LX874 (trade names, manufactured by Nippon Zeon Co., Ltd.), Polysol AT860 (trade name, manufactured by Showa Denko K.K.), Boncoat AN-1190S, YG-651, AC-501, AN-1170, 4001 (trade names, manufactured by DIC Corporation), and the like.

[0050] In this specification, the acrylic resin may be a styrene-acrylic resin as described above. In addition, in this specification, the term "(meth)acrylic" means at least one of acrylic and methacrylic.

[0051] Styrene-acrylic resins are copolymers obtained from styrene monomers and acrylic monomers, and examples thereof include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-α-methylstyrene-acrylic acid copolymers, etc. Commercially available styrene-acrylic resins may be used, such as JONCRYL 62J, 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, and 7610 (product names, manufactured by BASF), and Mowinyl 966A and 975N (product names, manufactured by Japan Coating Resins Co., Ltd.).

[0052] The vinyl chloride resin may be a vinyl chloride-vinyl acetate copolymer. Examples of the fat include polymers containing acrylic acid ester as a monomer, such as styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, and styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer.

[0053] The polyolefin resin has an olefin such as ethylene, propylene, or butylene in its structural skeleton, and known resins can be appropriately selected and used. As the olefin resin, commercially available products can be used, and for example, Arrowbase CB-1200, CD-1200 (trade names, manufactured by Unitika Ltd.), etc. may be selected and used.

[0054] The resin particles may be supplied in the form of an emulsion. Examples of commercially available resin emulsions include Microgel E-1002 and E-5002 (trade names, manufactured by Nippon Paint Co., Ltd., styrene acrylic resin emulsions), Boncoat AN-1190S, YG-651, AC-501, AN-1170, 4001, and 5454 (trade names, manufactured by DIC Corporation, styrene acrylic resin emulsions), Polysol AM-710, AM-920, AM-2300, AP-4735, AT-860, and PSASE-4210E (acrylic resin emulsions), and Polysol AM-710, AM-920, AM-2300, AP-4735, AT-860, and PSASE-4210E (acrylic resin emulsions). 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) (all trade names, manufactured by Showa Denko K.K.), Polysol SAE1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Saivinol SK-200 (acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.) ion), AE-120A (trade name, manufactured by JSR Corporation, acrylic resin emulsion), AE373D (trade name, manufactured by E-Tech Co., Ltd., carboxy-modified styrene acrylic resin emulsion), Seikadyne 1900W (trade name, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., ethylene-vinyl acetate resin emulsion), Vinyblan 2682 (acrylic resin emulsion), Vinyblan 2886 (vinyl acetate-acrylic resin emulsion), Vinyblan 5202 (acetic acid acrylic resin emulsion) (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), Vinyblan 700, 2586 (trade names, manufactured by Nissin Chemical Industry Co., Ltd.) (trade name, manufactured by Unitika Ltd., polyester resin emulsion), Hi-Tec SN-2002 (trade name, manufactured by Toho Chemical Co., Ltd., polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (trade name, manufactured by Mitsui Chemicals Polyurethanes, urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 620, 700 (trade name, manufactured by Mitsui Chemicals Polyurethanes, urethane resin emulsion),Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), Permarin UA-150 (trade name, Sanyo Chemical Industries, Ltd., urethane resin emulsion), Sancure 2710 (trade name, Lubrizol Japan, urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (trade name, Kusumoto Chemicals Co., Ltd., urethane resin emulsion), Adeka Bontiter HUX-380, 290K (product names, manufactured by ADEKA Corporation, urethane resin emulsion), Mowinyl 966A, Mowinyl 7320 (product names, manufactured by Japan Coating Resins Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7 The binder may be selected from 630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (all trade names, manufactured by BASF), NK Binder R-5HN (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.), Hydran WLS-210 (trade name, manufactured by DIC Corporation, non-crosslinked polyurethane), Joncryl 7610 (trade name, manufactured by BASF), and the like.

[0055] Furthermore, among these, the resin particles are preferably made of polyurethane, which has superior adhesion and abrasion resistance. It is more preferable that the resin particles be selected from the group consisting of ethylene resin, acrylic resin, ester resin, and vinyl chloride resin. Furthermore, if the resin particles contain acrylic resin particles, the adhesion and abrasion resistance of the components of the aqueous ink composition adhered to the recording medium can be further improved, which is preferable.

[0056] The resin particles may be composite resin particles having a phase-separated structure in which a phase (portion) made of a first resin and a phase (portion) made of a second resin are separated from each other.

[0057] The composite resin microparticles may have a form in which the first resin and the second resin constitute one part and the other part of the resin microparticle, respectively. Examples include composite resin microparticles with a core-shell structure in which one of the first resin and the second resin mainly constitutes the peripheral part (shell part) of the composite resin microparticles and the other mainly constitutes the central part (core part) of the resin microparticles, and composite resin microparticles with a sea-island structure in which the parts made of one of the first resin and the second resin exist in the form of islands in a sea of ​​the parts made of the other resin. In composite resin particles having a sea-island structure, the portion made of the other resin may be partially exposed on the outermost surface of the resin particle, and the islands may be distributed unevenly or not uniformly within the composite resin particles. The islands may be spherical or non-spherical, and may vary in size. Among these, composite resin particles having a sea-island structure consisting of a sea made of a first resin and islands made of a second resin are preferred because of their superior continuous discharge stability and abrasion resistance.

[0058] The first resin constituting a part of the composite resin particles may be a homopolymer or a copolymer.

[0059] The first resin is not particularly limited, but an acrylic resin can be used. Acrylic resins are resins having (meth)acrylic monomer units, and are preferred in that various physical properties can be easily controlled and they are readily available. The (meth)acrylic monomer unit is not particularly limited, but examples thereof include the same monomer components that can be used in the polymer of the polymer-dispersed pigment described above.

[0060] The acrylic resin may be a resin having a (meth)acrylic monomer unit and a monomer unit other than the (meth)acrylic monomer unit, which is preferred in that it is easy to adjust the various physical properties of the resin. Examples of the other monomer units include vinyl monomer units. The acrylic resin also preferably has an aromatic monomer unit. Examples of the aromatic monomer unit include aromatic vinyl monomer units and aromatic (meth)acrylic monomer units, and a resin having an aromatic vinyl monomer unit is preferred.

[0061] The second resin can be the same as the first resin described above, but can be configured as an independent resin from the first resin. The second resin is not particularly limited, but is preferably an acrylic resin having a (meth)acrylic monomer unit, like the first resin.

[0062] The method for synthesizing the composite resin microparticles is not particularly limited, and they can be synthesized by, for example, a known emulsion polymerization method or an appropriate combination thereof. Specific examples include a batch mixing polymerization method, a monomer dropping method, a pre-emulsion method, a seed emulsion polymerization method, a multi-stage emulsion polymerization method (such as a two-stage emulsion polymerization method), and a phase inversion emulsion polymerization method. Regarding the method for producing the sea-island structure resin microparticles and the core-shell resin microparticles, see, for example, Colloids and Surfaces A: Please refer to Physiochemical and Engineering Aspects 153(1999) 255-270.

[0063] The resins may be used alone or in combination of two or more.

[0064] In the inkjet ink composition according to this embodiment, when the resin contains resin particles, the resin particles preferably have a glass transition point of 50 to 110° C. Furthermore, the volume average particle diameter is preferably 90 to 220 nm. The lower limit of the glass transition temperature (Tg) of the resin particles is more preferably 60° C. or higher, even more preferably 70° C. or higher, and particularly preferably 80° C. or higher. The upper limit is more preferably 105° C. or lower, even more preferably 100° C. or lower, and particularly preferably 95° C. or lower. The lower limit of the volume average particle diameter of the resin particles is preferably 100 nm or more, more preferably 110 nm or more, particularly preferably 120 nm or more, and even more particularly preferably 130 nm or more, and the upper limit is preferably 200 nm or less, more preferably 180 nm or less, particularly preferably 160 nm or less, and even more particularly preferably 150 nm or less. When the glass transition point and volume average particle size of the resin particles are within the above ranges, it tends to be possible to achieve a good balance between abrasion resistance and clogging recovery properties.

[0065] The glass transition point (Tg) can be confirmed by a standard method such as differential scanning calorimetry (DSC).

[0066] Furthermore, in the inkjet ink composition according to this embodiment, the resin is resin particles, and the ratio (B / A) of the volume average particle diameter B of the resin particles to the volume average particle diameter A of the pigment is preferably 0.6 to 1.8, more preferably 0.8 to 1.6, even more preferably 1.0 to 1.5, and particularly preferably 1.2 to 1.4. When the ratio (B / A) of the volume average particle diameter B of the resin particles to the volume average particle diameter A of the pigment is within the above range, it tends to be possible to achieve a good balance between abrasion resistance and clogging recovery properties.

[0067] The resin content, as solid content, is preferably 0.5% by mass or more and 20.0% by mass or less, more preferably 1.0% by mass or more and 15.0% by mass or less, even more preferably 2.0% by mass or more and 10.0% by mass or less, and particularly preferably 3.0% by mass or more and 8.0% by mass or less, relative to the total mass of the ink composition.

[0068] 1.3 Water The inkjet ink composition according to this embodiment is an aqueous ink and contains water. Here, the term "aqueous" in the "aqueous" ink of the present invention refers to an ink containing at least water as a primary solvent. The water is preferably pure water or ultrapure water, such as ion-exchanged water, ultrafiltered water, reverse osmosis water, or distilled water, from which ionic impurities have been removed as much as possible. Furthermore, using water that has been sterilized by ultraviolet irradiation or the addition of hydrogen peroxide is preferable, as this can prevent the growth of mold and bacteria when the ink is stored for a long period of time.

[0069] The water content of the ink composition is preferably 45% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to the total mass of the ink composition. There is no upper limit, but it is preferably 98% by mass or less. The content of the organic solvent in the ink composition is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, and particularly preferably 20% by mass or less, relative to the total mass of the ink composition.

[0070] 1.4 Certain small organic compounds The inkjet ink composition according to this embodiment contains a water-soluble low-molecular-weight organic compound (specific low-molecular-weight organic compound) that has a melting point of 30°C or higher and is either an amide, a sulfur-containing compound, or a cyclic ether, in an amount of 10% by mass or less relative to the total mass of the ink composition.

[0071] The amides may be water-soluble low-molecular-weight organic compounds having an amide structure. Examples of water-soluble low-molecular-weight organic compounds having a melting point of 30°C or higher include cyclic amides such as ε-caprolactam (standard boiling point 267°C, melting point 70°C, molecular weight 113), 2-piperidone (standard boiling point 256°C, melting point 38°C, molecular weight 99), ω-heptalactam (standard boiling point 288°C, melting point 36°C, molecular weight 127), succinimide (standard boiling point 287°C, melting point 125°C, molecular weight 99), and 5-methyl-2-pyrrolidone (standard boiling point 248°C, melting point 38°C, molecular weight 99), as well as non-cyclic amides such as acetoacetamide (standard boiling point 271°C, melting point 52°C, molecular weight 101). Cyclic amides are preferred because they tend to improve abrasion resistance and clogging recovery.

[0072] The sulfur-containing compound may be a water-soluble low-molecular-weight organic compound having a sulfur atom in the molecule. Examples of water-soluble low-molecular-weight organic compounds having a melting point of 30°C or higher that are sulfur-containing compounds include sulfones. Examples include dimethyl sulfone (standard boiling point 248°C, melting point 110°C, molecular weight 94), diethyl sulfone (standard boiling point 246°C, melting point 73°C, molecular weight 122), and ethyl methyl sulfone (standard boiling point 245°C, melting point 34°C, molecular weight 108).

[0073] The cyclic ethers may be water-soluble low-molecular-weight organic compounds having a cyclic ether structure. Examples of water-soluble low-molecular-weight organic compounds having a melting point of 30°C or higher and being cyclic ethers include 1,4-dioxane-2,3-diol (normal boiling point 259°C, melting point 114°C, molecular weight 120) and isosorbide (normal boiling point 372°C, melting point 61°C, molecular weight 146).

[0074] The specific low-molecular-weight organic compound is a water-soluble compound, and water-solubility means, for example, that after mixing 10% by mass of the compound in water and stirring thoroughly at room temperature, no undissolved residue is visible to the naked eye and the entire mixture does not appear cloudy.

[0075] The specific low molecular weight organic compounds may be used alone or in combination of two or more.

[0076] The molecular weight of the specific low-molecular organic compound is preferably 300 or less, more preferably 30 to 250, even more preferably 50 to 200, and particularly preferably 70 to 150.

[0077] The melting point of the specific low-molecular-weight organic compound is not particularly limited as long as it is 30° C. or higher, but is preferably 40° C. or higher, more preferably 50° C. or higher, even more preferably 60° C. or higher, and particularly preferably 70° C. or higher. The upper limit of the melting point is preferably 150° C. or lower, more preferably 140° C. or lower, even more preferably 130° C. or lower, and particularly preferably 120° C. or lower. Furthermore, 100° C. or lower is preferred. The melting point of a specific low-molecular-weight organic compound can be confirmed by a standard method such as differential scanning calorimetry (DSC).

[0078] The specific low-molecular-weight organic compound preferably has a standard boiling point of 280°C or lower, more preferably 270°C or lower, even more preferably 260°C or lower, and particularly preferably 250°C or lower. The lower limit of the standard boiling point of the specific low-molecular-weight organic compound is preferably 200°C or higher, more preferably 210°C or higher, even more preferably 220°C or higher, and particularly preferably 230°C or higher. Furthermore, 250°C or higher is preferred, and 260°C or higher is more preferred. When the normal boiling point of the specific low-molecular organic compound is within the above range, the pinning effect due to the thickening of the ink and the drying property can be favorably achieved at the same time, and the image quality (aggregation unevenness) and the abrasion resistance can be balanced and excellent. It tends to be possible to do this.

[0079] The upper limit of the content of the specific low-molecular-weight organic compound is 10% by mass or less, preferably 9.0% by mass or less, more preferably 8.0% by mass or less, even more preferably 7.0% by mass or less, particularly preferably 6.0% by mass or less, and particularly preferably 5.0% by mass or less, relative to the total mass of the ink composition. The lower limit is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.5% by mass or more, particularly preferably 2.0% by mass or more, even particularly preferably 2.5% by mass or more, particularly preferably 3.0% by mass or more, and particularly preferably 3.5% by mass or more, relative to the total mass of the ink composition. When the content of the specific low-molecular-weight organic compound is within the above range, it tends to be possible to achieve a balanced improvement in image quality (uneven aggregation), impact misalignment, image quality (uneven gloss), etc.

[0080] 1.5 Certain diols The inkjet ink composition according to this embodiment contains a diol organic solvent (specific diol) having a melting point of 25° C. or less in a content greater than the content of the specific low-molecular organic compound. The organic solvent is liquid at room temperature.

[0081] Furthermore, the mass ratio (A / B) of the content A of the organic solvent (specific diols) that is a diol having a melting point of 25°C or less to the content B of the low molecular weight organic compound (specific low molecular weight organic compound) is preferably 1.3 to 10, more preferably 1.5 to 9.0, even more preferably 2.0 to 5.0, and particularly preferably 2.5 to 4.5. When the mass ratio (A / B) of the content A of the specific diol to the content B of the specific low-molecular-weight organic compound is within the above range, it tends to be possible to achieve a good balance of properties such as ink impact misalignment, abrasion resistance, and clogging recovery.

[0082] The content of the organic solvent (specific diol) that is a diol having a melting point of 25°C or less is preferably 5 to 30% by mass relative to the total mass of the ink composition. The lower limit of the content of the specific diol is more preferably 6% by mass or more, even more preferably 7% by mass or more, particularly preferably 8% by mass or more, and even more particularly preferably 9% by mass or more. The upper limit is more preferably 25% by mass or less, even more preferably 20% by mass or less, particularly preferably 17% by mass or less, and even more particularly preferably 14% by mass or less. When the content of the specific diol is within the above range, it tends to be possible to achieve a good balance of properties such as ink impact deviation, abrasion resistance, and clogging recovery.

[0083] 1.5.1 Specific types of diols Diols are organic compounds having two hydroxyl groups in the molecule. Examples of diols include alkanediols in which an alkane is substituted with two hydroxyl groups, and condensates in which the hydroxyl groups of two or more molecules of such alkanediol are condensed together. The specific diols preferably have 2 to 10 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms in the molecule.

[0084] Examples of organic solvents (specific diols) that are diols with a melting point of 25°C or less include 1,2-alkanediols such as ethylene glycol (also known as ethane-1,2-diol, melting point -13°C, standard boiling point 197°C), propylene glycol (also known as propane-1,2-diol, melting point -59°C, standard boiling point 188°C), 1,2-butanediol (melting point -50°C, standard boiling point 192°C), 1,2-pentanediol (melting point -40°C, standard boiling point 209°C), and 1,2-hexanediol (melting point -40°C, standard boiling point 224°C); diethylene glycol (melting point -8°C, standard boiling point 244°C), dipropylene glycol (melting point -39°C, standard boiling point 244°C), and propylene glycol (melting point -39°C, standard boiling point 244°C). Standard boiling point 231°C), triethylene glycol (melting point -7°C, standard boiling point 287°C), tripropylene glycol (melting point -20°C, standard boiling point 270°C), 1,3-propanediol (melting point -27°C, standard boiling point 213°C), 1,3-butanediol (also known as 1,3-butylene glycol, melting point -77°C, standard boiling point 207°C), 1,4-butanediol (melting point 19°C, standard boiling point 235°C), 2,3-butanediol (melting point 20°C, standard boiling point 176°C), 1,5-pentanediol (melting point -16°C, standard boiling point 242°C), 2-methylpropanediol (melting point -16°C, standard boiling point 242°C), Examples of alkanediols include 2-ethyl-1,3-propanediol (melting point -91°C, standard boiling point 214°C), 3-methyl-1,3-butanediol (melting point -25°C, standard boiling point 203°C), 3-methyl-1,5-pentanediol (melting point -10°C, standard boiling point 249°C), 2-ethyl-1,3-hexanediol (melting point -40°C, standard boiling point 243°C), 3-methyl-1,5-pentanediol (melting point -60°C, standard boiling point 150°C), and 2-methylpentane-2,4-diol (melting point -40°C, standard boiling point 197°C).

[0085] Among the specific diols, 1,2-alkanediols are preferred, and an organic solvent selected from ethylene glycol, propylene glycol, 1,2-butanediol, and 1,2-hexanediol is more preferred.

[0086] The specific diols may be used alone or in combination of two or more.

[0087] The organic solvent (specific diol) which is a diol having a melting point of 25°C or less preferably contains an organic solvent having a standard boiling point of 170 to 250°C, more preferably contains an organic solvent having a standard boiling point of 190 to 240°C, and even more preferably contains an organic solvent having a standard boiling point of 210 to 230°C. Alternatively, the standard boiling point is preferably 180 to 220°C, more preferably 180 to 210°C, and even more preferably 180 to 200°C. When the normal boiling point of the specific diol is within the above range, the drying property is further improved and the abrasion resistance tends to be more excellent.

[0088] The melting point of the specific diol is preferably from -100 to 25°C, more preferably from -80 to 0°C, and even more preferably from -80 to -20°C.

[0089] 1.5.2 Other low molecular weight organic compounds The inkjet ink composition according to this embodiment may contain a low molecular weight organic compound other than the specific low molecular weight organic compound and the specific diols described above. The low molecular weight organic compound may be an organic solvent, and an organic solvent is preferred. Examples of such other low molecular weight organic compounds include polyhydric alcohols, esters, cyclic esters, alkylene glycol ethers, amides other than the specific low molecular weight organic compounds described above, sulfur-containing compounds, and cyclic ethers.

[0090] Polyhydric alcohols are compounds having two or more hydroxyl groups in the molecule. However, this definition refers to compounds other than the specific diols mentioned above. Examples of polyhydric alcohols include alkane polyols in which an alkane is substituted with two or more hydroxyl groups, and condensates in which the hydroxyl groups of two or more molecules of such alkane polyols are condensed together. Examples of polyhydric alcohols include diols other than specific diols such as 1,2-octanediol (melting point 36°C), 1,6-hexanediol (melting point 43°C), 2-ethyl-2-methyl-1,3-propanediol (melting point 43°C), 2-methyl-2-propyl-1,3-propanediol (melting point 57°C), 2,2-dimethyl-1,3-propanediol (melting point 128°C), and 2,3-dimethyl-2,3-butanediol (melting point 43°C), as well as trimethylolpropane and glycerin.

[0091] Examples of esters include glycol monoacetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate; Examples of glycol diesters include ethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, and dipropylene glycol acetate propionate.

[0092] Examples of cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen atom of the methylene group adjacent to the carbonyl group of these cyclic esters is substituted with an alkyl group having 1 to 4 carbon atoms.

[0093] The alkylene glycol ethers may be monoethers or diethers of alkylene glycol, and alkyl ethers are preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, and the like. and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0094] Examples of the amides include acyclic amides, cyclic amides, etc. Examples of the acyclic amides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy- Examples include alkoxyalkylamides such as 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; 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-dimethylpropionamide. Examples of cyclic amides include lactams, such as pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone, N-methyl-ε-caprolactam, N-cyclohexyl-2-pyrrolidone, and β-propiolactam.

[0095] Examples of sulfur-containing compounds include sulfoxides and sulfones. Examples of sulfoxides include acyclic sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide, and cyclic sulfoxides such as tetramethylene sulfoxide. Examples of sulfones include cyclic sulfones such as 3-methyl sulfolane and sulfolane, and acyclic sulfones such as ethyl isopropyl sulfone.

[0096] Examples of cyclic ethers include tetrahydrofuran, 1,4-dioxane, dimethylisosorbide, 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol, 2-hydroxymethyloxetane, tetrahydrofurfuryl alcohol, glycerol formal, solketal, and dihydrolevoglucosenone.

[0097] The other low molecular weight organic compounds may be used singly or in combination of two or more.

[0098] The ink of this embodiment preferably does not contain more than 1% by mass of organic solvents that are polyhydric alcohols with a normal boiling point above 280°C. It is more preferable that the content does not exceed 0.5% by mass, and even more preferable that the ink does not contain any organic solvents. Here, organic solvents that are polyhydric alcohols with a normal boiling point above 280°C also include the aforementioned specific diols and other low-molecular-weight organic compounds with a normal boiling point above 280°C. This is preferable because it provides better abrasion resistance and other properties. It is also preferable that the content of the organic solvent having a normal boiling point of more than 280°C is within the above range.

[0099] 1.6 Wax The inkjet ink composition according to this embodiment may contain wax, such as plant or animal waxes, such as carnauba wax, candelilla wax, beeswax, rice wax, and lanolin; or mineral waxes, such as montan wax and ozokerite. These waxes include petroleum-based waxes, such as paraffin wax; carbon wax, Hoechst wax, polyolefin wax, silicone wax, synthetic waxes such as stearic acid amide, and natural and synthetic wax emulsions and blended waxes such as α-olefin-maleic anhydride copolymers. These waxes impart slip properties to the surface of the recorded material and improve abrasion resistance, thereby improving the abrasion resistance of the recorded material. These waxes can be used alone or in combination. Among these, silicone wax, polyolefin wax, paraffin wax, etc. are preferably used.

[0100] Commercially available silicone waxes include, for example, SM8706EX, SM7036EX, SM7060EX, SM7025EX, SM490EX, SM8701EX, SM8709SR, SM8716SR, IE-7045, IE-7046T, SH7024, BY22-744EX, BY22-818EX, FZ-4658, FZ-4634EX, and FZ-4602 (all trade names, manufactured by Dow Corning Toray Co., Ltd.), POLON-MF-14, POLON-MF-14EC, and POLON-MF-2 3 Examples of such polyolefin copolymers include POLON-MF-63, POLON-MF-18T, POLON-MF-56, POLON-MF-49, POLON-MF-33A, POLON-MF-55T, POLON-MF-28T, POLON-MF-50, POLON-MK-206, POLON-SR-CONC, KM-9771, KM-9774, KM-2002-T, KM-2002-L-1, KM-9772, KS-7002, KS-701, and X-51-1264 (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0101] Examples of polyolefin waxes include waxes produced from olefins such as ethylene, propylene, and butylene, or their derivatives, and copolymers thereof, specifically polyethylene waxes, polypropylene waxes, and polybutylene waxes. Polyolefin waxes can be used alone or in combination of two or more. Among these, polyethylene waxes are preferred.

[0102] Commercially available polyolefin waxes include, for example, the AQUACER series, such as AQUACER 513 (polyethylene wax, average particle size 100 nm to 200 nm, melting point 130°C, solids content 30%), AQUACER 507, AQUACER 515, AQUACER 840, and AQUACER 1547 (all trade names, manufactured by BYK Japan Co., Ltd.); the Hitec series, such as Hitec E-7025P, Hitec E-2213, Hitec E-6500, Hitec E-6314, Hitec E-9460, Hitec E-9015, Hitec E-4A, Hitec E-5403P, and Hitec E-8237 (all trade names, manufactured by Toho Chemical Industry Co., Ltd., polyethylene wax); and Nopcoat PEM-17 (trade name, manufactured by San Nopco, polyethylene emulsion, average particle size 40 nm).

[0103] Paraffin wax is a so-called petroleum wax. Here, paraffin refers to an alkane having 20 or more carbon atoms. In this embodiment, paraffin wax refers to a mixture of hydrocarbons with a molecular weight of about 300 to 500, mainly consisting of linear paraffin hydrocarbons having 20 to 30 carbon atoms and containing a small amount of isoparaffin.

[0104] Commercially available paraffin wax products include, for example, AQUACER 537 and AQUACER 539 (trade names, manufactured by BYK Japan KK).

[0105] The wax content, calculated as solid content, is preferably 0.1% by mass or more and 10.0% by mass or less, more preferably 0.2% by mass or more and 5.0% by mass or less, and even more preferably 0.5% by mass or more and 1.0% by mass or less, relative to the total mass of the ink composition.

[0106] 1.7 Antifoaming agents The inkjet ink composition according to this embodiment may contain an antifoaming agent. Examples of antifoaming agents include, but are not limited to, silicone-based antifoaming agents, polyether-based antifoaming agents, fatty acid ester-based antifoaming agents, and acetylene glycol-based antifoaming agents. Among these, silicone-based antifoaming agents and acetylene glycol-based antifoaming agents are preferred because they are excellent at maintaining appropriate surface tension and interfacial tension and rarely generate bubbles. Furthermore, the antifoaming agent preferably has an HLB value of 6 or less, based on the Griffin method.

[0107] The HLB value based on the Griffin method in this specification is a value proposed by Griffin to evaluate the hydrophilicity of a compound, and refers to a value calculated by the following formula (1): The HLB value based on the Griffin method indicates a value within the range of 0 to 20, and the larger the value, the more hydrophilic the compound is. HLB value = 20 × (mass % of hydrophilic groups) = 20 × (total formula weight of hydrophilic groups / molecular weight of surfactant) Equation (1)

[0108] The antifoaming agent with an HLB value of 6 or less is not particularly limited, but specific examples include Surfynol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, DF-110D, and 82 (all trade names, Air Products and Chemicals). Inc.), 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 Co., Ltd.).

[0109] The content of the antifoaming agent is preferably from 0.01% by mass to 1.00% by mass, more preferably from 0.03% by mass to 0.50% by mass, and even more preferably from 0.05% by mass to 0.20% by mass, relative to the total mass of the ink composition.

[0110] 1.8 Surfactants The inkjet ink composition according to this embodiment may contain a surfactant (excluding those listed above as antifoaming agents; in other words, limited to those having an HLB value of greater than 6 according to the Griffin method). Examples of surfactants include, but are not limited to, nonionic surfactants. Nonionic surfactants have the effect of spreading ink evenly on a recording medium. Therefore, when inkjet recording is performed using an ink containing a nonionic surfactant, high-resolution images with almost no bleeding can be obtained. Examples of such nonionic surfactants include, but are not limited to, silicone-based, polyoxyethylene alkyl ether-based, polyoxypropylene alkyl ether-based, polycyclic phenyl ether-based, sorbitan derivative, and fluorine-based surfactants, with silicone-based surfactants being preferred.

[0111] The silicone surfactant is not particularly limited, but a polysiloxane compound is preferred. The polysiloxane compound is not particularly limited, but examples thereof include polyether-modified organosiloxane. Commercially available polyether-modified organosiloxanes include, but are not limited to, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-349, BYK-3420, BYK-3480, and BYK-3481 (all trade names, manufactured by BYK), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, and KF-6013. F-6015, KF-6017 (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.), SAG002, SAG003, SAG502, SAG503A, SAG005, SAG008, SAG016, SAG020 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), TEGO WET 260, TEGO WET 270, TEGO WET 280, TEGO WET KL245 (all trade names, manufactured by Evonik Japan K.K.), DOWSIL 502W (trade name, manufactured by Dow Toray Co., Ltd.), and the like.

[0112] The content of the surfactant is preferably 0.05% by mass or more and 5.00% by mass or less, more preferably 0.15% by mass or more and 2.50% by mass or less, and even more preferably 0.10% by mass or more and 1.00% by mass or less, relative to the total mass of the ink composition.

[0113] 1.9 Alkanolamines The inkjet ink composition according to this embodiment may contain alkanolamines. Alkanolamines can adjust the pH of the ink composition and tend to increase the viscosity of the ink, which may improve the pinning effect and image quality (reduction of aggregation unevenness).

[0114] Examples of alkanolamines include monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, N-aminoethylethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-tert-butylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, N-tert-butyldiethanolamine, 2-amino-1-propanol, 2-amino-2-methyl-1 -propanol, 5-amino-1-pentanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-hydroxymethyl-1,3-propanediol, 3-amino-1,2-propanediol, 3-methylamino-1,2-propanediol, propanolamine, N,N-dimethylpropanolamine, N,N-diethylpropanolamine, tripropanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, N,N-dimethylisopropanolamine, N,N-diethylisopropanolamine, and the like.

[0115] The content of alkanolamines is preferably 0.1% by mass or more and 10.0% by mass or less, more preferably 0.3% by mass or more and 5.0% by mass or less, and even more preferably 0.5% by mass or more and 3.0% by mass or less, relative to the total mass of the ink composition.

[0116] 1.10 Other Ingredients The inkjet ink composition according to this embodiment may further contain components such as preservatives, antifungals, rust inhibitors, chelating agents, viscosity modifiers, antioxidants, and antifungal agents, as required.

[0117] 1.11 Methods for preparing inkjet ink compositions The inkjet ink composition according to this embodiment can be obtained by mixing the above-described components in any order and, if necessary, removing impurities by filtration or the like. A suitable method for mixing the components is to sequentially add the materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and then stir and mix them. As a filtration method, centrifugal filtration, filter filtration, or the like can be used as necessary.

[0118] 1.12 Physical properties of inkjet ink compositions From the viewpoint of balancing image quality and reliability as an inkjet recording ink, the inkjet ink composition according to this embodiment preferably has a surface tension of 18 mN / m to 40 mN / m at 20° C., more preferably 20 mN / m to 35 mN / m, and even more preferably 22 mN / m to 33 mN / m. The surface tension can be measured, for example, by using an automatic surface tensiometer CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.) to check the surface tension when a platinum plate is wetted with the ink in an environment of 20° C.

[0119] From the same viewpoint, the viscosity of the inkjet ink composition according to this embodiment at 20° C. is preferably from 3 mPa·s to 10 mPa·s, and more preferably from 3 mPa·s to 8 mPa·s. The viscosity can be measured at 20° C. using, for example, a viscoelasticity tester MCR-300 (trade name, manufactured by Pysica).

[0120] 1.13 Uses of inkjet ink compositions The inkjet ink composition according to this embodiment is used for recording on low-absorbency recording media or non-absorbency recording media.

[0121] A low-absorbency recording medium or a non-absorbency recording medium refers to a recording medium that does not absorb liquid such as ink at all or absorbs very little of it. Quantitatively, a low-absorbency recording medium or a non-absorbency recording medium is a recording medium that absorbs ink 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 the amount of 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 "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition." In contrast, absorbent recording media refers to recording media that do not fall under the category of non-absorbent or low-absorbent.

[0122] Non-absorbent recording media include those with a recording surface made of plastic. Here, the surface of the recording surface does not have an absorption layer or a receiving layer for absorbing liquid. Examples include those in which a plastic is coated on a substrate such as paper, those in which a plastic film is adhered to a substrate such as paper, and plastic films without an absorption layer or a receiving layer. Examples of plastics include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc.

[0123] The low-absorbency recording medium may be a recording medium called coated paper, which has a coating layer on its surface. For example, when the substrate is paper, printing paper such as art paper, coated paper, or matte paper may be used. When the substrate is a plastic film, the substrate may be polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, or polypropylene, coated with a hydrophilic polymer or the like, or coated with particles of silica, titanium, or the like together with a binder.

[0124] The inkjet ink composition according to this embodiment can also be suitably used for recording on flexible packaging films. Flexible packaging films are one embodiment of the non-absorbent recording media described above. More specifically, flexible packaging films are highly flexible film materials used for packaging food, toiletries, cosmetics, etc., and have anti-fogging and anti-static properties, antioxidants, etc. present on the film surface, and have a thickness in the range of 5 to 70 μm, preferably 10 to 50 μm. When an ink composition is applied to this film, a film of normal thickness is used. However, the inkjet ink composition according to this embodiment tends to provide excellent abrasion resistance and image quality (uneven aggregation) even when used on flexible packaging films.

[0125] The material constituting the recording surface of the flexible packaging film can contain at least one resin selected from olefin-based resins such as polyethylene and polypropylene, ester-based resins such as polyester, vinyl chloride-based resins such as polyvinyl chloride, and amide-based resins such as polyamide. The film substrate comprising the recording surface of the flexible packaging film can be a film or sheet made from these resins. In the case of a film or sheet made from a resin, either an unstretched film or a uniaxially or biaxially stretched film can be used, with biaxially stretched films being preferred. Furthermore, if necessary, films or sheets made from these various resins can be laminated together and used.

[0126] The inkjet ink composition according to this embodiment can also be suitably used for recording on recording media for sign graphics. Sign graphics recording media are made from a wide variety of materials, including banners, coated paper, matte paper, wallpaper, fabric, and plastic films such as PET and PVC. However, the inkjet ink composition according to this embodiment is particularly suitable for use on transparent or translucent plastic films used for window displays, car wrapping, and the like. These films often have a flexible substrate made of polyolefin, PET, PVC, or the like, and an adhesive layer on the side opposite the printed surface. After printing, the adhesive surface is attached to a window glass, car body, or the like. When applying ink to such films, the ink tends to adhere more poorly and bleed more easily, resulting in poor abrasion resistance and poor image quality (uneven aggregation). However, the inkjet ink composition according to this embodiment tends to provide excellent abrasion resistance and image quality (uneven aggregation) even on recording media for sign graphics.

[0127] The material constituting the recording surface of the sign graphics film can contain at least one resin selected from olefin resins such as polyethylene and polypropylene, ester resins such as polyester, vinyl chloride resins such as polyvinyl chloride, and amide resins such as polyamide.

[0128] The recording medium may be colorless and transparent, semi-transparent, colored and transparent, colored and opaque, colorless and opaque, or the like.

[0129] 2. Recording method A recording method according to an embodiment of the present invention includes: The method includes a step of ejecting the ink-jet ink composition from an ink-jet head and depositing it onto a recording medium, the recording medium being a low-absorbency recording medium or a non-absorbency recording medium.

[0130] According to the recording method of this embodiment, when recording on a low-absorbency or non-absorbency recording medium, it is possible to achieve excellent abrasion resistance and image quality (aggregation unevenness), and to significantly reduce impact deviation.

[0131] When using water-based ink to record on low-absorbency or non-absorbency recording media, the ink is difficult to absorb into the recording medium, so when adjacent ink droplets (dots) that land on the recording medium come into contact, the dots gather together, resulting in a decrease in image quality (aggregation unevenness).To address this problem, a treatment liquid containing an aggregating agent that aggregates the ink components is used in combination. While this technology is well known, the use of a treatment liquid has drawbacks such as reduced abrasion resistance, etc. Also, while a primary heating step in which ink adhered to a recording medium is heated and dried at an early stage can reduce dot aggregation, the drawbacks of heating include the occurrence of gloss unevenness (gloss banding), poor recovery from clogging, and increased condensation on the inkjet head.

[0132] The present inventors have now discovered that by incorporating a water-soluble low-molecular-weight organic compound (specific low-molecular-weight organic compound) having a melting point of 30°C or higher and belonging to any of the following groups: amides, sulfur-containing compounds, and cyclic ethers, into the ink used in a recording method, image quality (agglomeration unevenness) can be significantly improved, even without the use of a treatment liquid. It is believed that the inclusion of the specific low-molecular-weight organic compound in the ink makes the ink more viscous when it dries, thereby suppressing dot migration and allowing dots to be fixed early before they clump together. In other words, excellent image quality (agglomeration unevenness) is achieved not by the reaction between the treatment liquid and the ink (pinning effect), but by the pinning effect of the ink itself, which contains the specific component. Furthermore, the specific low-molecular-weight organic compound also has resin-solubility, which allows it to swell and dissolve resins contained in the ink and low-absorbency or non-absorbency recording media. Therefore, the inclusion of the specific low-molecular-weight organic compound in the ink not only achieves excellent image quality (agglomeration unevenness), but also excellent abrasion resistance.

[0133] On the other hand, when the ink used in the recording method contains a specific low-molecular-weight organic compound, a new problem has arisen: the ink droplets do not land on the correct position. This is thought to be because the ink containing the specific low-molecular-weight organic compound is prone to change in ejection characteristics, and the ejection direction and ejection speed of the ink droplets are prone to fluctuate when and after ejection from the inkjet head. In particular, we think that the increase in viscosity as the ink dries is related to this problem. Therefore, the present inventors conducted further intensive research and found that by incorporating an organic solvent (specific diols) that is a diol having a melting point of 25°C or less in an amount greater than that of the specific low-molecular-weight organic compound, and by keeping the content of the specific low-molecular-weight organic compound at a predetermined amount or less, it is possible to significantly reduce impact deviation and obtain excellent image quality (agglomeration unevenness) and excellent abrasion resistance.

[0134] Hereinafter, each step of the recording method according to this embodiment and an inkjet recording apparatus applicable to the recording method will be described.

[0135] 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 (ink depositing step), and the recording medium is a low-absorbency recording medium or a non-absorbency recording medium.

[0136] As the recording medium, the same recording medium as that applied to the ink-jet ink composition described above can be used, and the details are as described above.

[0137] The ink deposition step can be easily carried out, for example, by using an inkjet recording apparatus 1 as shown in Fig. 1, which will be described later, to eject ink from an inkjet head 2. Note that a composition used for recording by ejecting ink from an inkjet head using an inkjet method is called an inkjet ink composition.

[0138] The amount of inkjet ink composition applied is 1 to 40 mg / inch per unit area of ​​the recording region of the recording medium.2 is preferably 2 to 30 mg / inch 2 More preferably, it is 4 to 20 mg / inch. 2 More preferably, it is 6 to 16 mg / inch. 2 In recording, it is particularly preferable that the recording area of ​​the recording medium is It is also preferable that the maximum amount of ink adhered is within the above range.

[0139] Furthermore, the ink deposition step of the recording method according to this embodiment preferably involves multiple main scans in which the relative position between the recording medium and the inkjet head is moved while the inkjet ink composition described above is ejected from the inkjet head, and the number of main scans in the same main scanning region is preferably 10 or less. The upper limit of the number of main scans in the same main scanning region is more preferably 9 or less, even more preferably 7 or less, particularly preferably 6 or less, and even more particularly preferably 5 or less. The lower limit is 1 or more, and is not particularly limited, but is preferably 2 or more, and more preferably 3 or more. When the resolution, which is the number of dots (number of ink droplets) per unit area, and the amount of ink applied are fixed, a smaller number of main scans is useful because it increases the printing speed. It is also preferable because it reduces condensation on the head. On the other hand, if the number of main scans is small, the number of dots ejected simultaneously increases, causing ink droplets to gather together and resulting in poor image quality (aggregation unevenness). However, with the recording method according to this embodiment, it is possible to ensure good image quality (reduced aggregation unevenness) even with the number of main scans (number of passes) within the above range.

[0140] It should be noted that "main scanning that moves the relative positions of the recording medium and the inkjet head" refers to scanning performed by the inkjet head 2, which is a serial recording head, relative to the recording medium M in the main scanning direction MS (i.e., in the direction of either the arrow S1 or the arrow S2) when using, for example, an inkjet recording device 1 as shown in Figures 1 and 2. Furthermore, the "number of main scans performed on the same scanning area" refers to the total number of main scans performed by the inkjet head 2 on the same position on the recording medium M, when a main scan is performed again so that the area overlaps at least partially with the area scanned by the inkjet head 2 on the recording medium M after a single main scan. For example, if the distance of one sub-scan (transporting the recording medium M) is shorter than the length of the nozzle array (not shown) that ejects ink in the sub-scanning direction SS, the area scanned by one main scan will be scanned again. For example, if the distance of one sub-scan is one-eighth the length of the nozzle array (not shown) that ejects ink in the sub-scanning direction SS, eight main scans will be performed on the same scanning area. In this case, the number of main scans is said to be eight.

[0141] In the main scanning, the time for one main scanning pass is preferably 0.5 to 5 seconds, more preferably 1 to 4 seconds, and even more preferably 2 to 3 seconds. The time for one main scanning pass (also referred to as the main scanning time) is the time required for the head to move from a position facing one edge of the recording medium to a position facing the other edge of the recording medium in one main scanning pass. A long main scanning time is useful because it enables recording of an image with a wider width in the main scanning direction, whereas a short main scanning time is preferable because it reduces condensation on the head. Head condensation is the formation of condensation on the nozzle surface of the head, which occurs when water that evaporates as the ink dries condenses and adheres to the head.

[0142] The ink application step may be carried out so that the surface temperature of the recording medium is 45° C. or less when the inkjet ink composition is applied to the recording medium. That is, the ink application step may be carried out without heating the recording medium or with heating, and even if heating is carried out, it is preferable to heat the recording medium so that the surface temperature is 45° C. or less. When heating the recording medium, it is preferable to include a primary heating step, which will be described later. The upper limit of the surface temperature of the recording medium is more preferably 42° C. or less, even more preferably 38° C. or less, particularly preferably 32° C. or less, and even more particularly preferably 28° C. or less. The lower limit is preferably 20° C. or more, more preferably 23° C. or more, and particularly preferably 25° C. or more. Furthermore, when a primary heating step is performed, the temperature is preferably 30° C. or more, and more preferably 35° C. or more.

[0143] When the surface temperature of the recording medium is high when the inkjet ink composition is applied to the recording medium, the ink applied to the recording medium can be dried at an early stage, which tends to reduce dot aggregation, but the drawbacks of this are the occurrence of gloss unevenness (gloss banding unevenness), deterioration of clogging recovery, increased condensation on the inkjet head, etc. In contrast, according to the recording method of this embodiment, even if the surface temperature of the recording medium in the ink application step is within the above range, particularly below the above range, excellent image quality (aggregation unevenness) can be obtained, and therefore excellent gloss unevenness (gloss banding unevenness), clogging recovery, and condensation can also be achieved.

[0144] 2.2 Primary heating process The recording method according to this embodiment may include a primary heating step of heating the inkjet ink composition applied to the recording medium. By including such a step, it is easy to control the surface temperature of the recording medium to a suitable temperature when the inkjet ink composition is applied to the recording medium. This makes it easier to obtain excellent image quality (aggregation unevenness).

[0145] The primary heating step is a step of heating and drying the ink adhered to the recording medium at an early stage. The primary heating step is a heating step for drying at least a portion of the ink solvent component to an extent that at least the ink flow is reduced. The primary heating step may be performed by adhering the ink to a heated recording medium, or by heating the ink early after adhering. In the primary heating step, it is preferable that heating of the ink droplets that have landed on the recording medium is initiated within 0.5 seconds at the latest after the ink droplets land on the recording medium.

[0146] The primary heating step is preferably performed by using an IR heater, microwave radiation, a platen heater, or blowing hot air onto the recording medium using a fan. That is, examples of heating methods include a conduction type such as a platen heater, a radiation type using IR or microwave radiation, and a blowing type using a fan, etc. Any one or more of these may be used.

[0147] When using an air blower in combination with another heating method, room temperature air may be used as the air blower. That is, room temperature air may be used as the air blower. Room temperature air can also be used as the air blower, as it can promote drying of ink and is preferable because it has better clogging recovery properties. On the other hand, when heating is performed by blowing air, hot air is preferred.

[0148] When using an air blower, the air velocity is preferably 0.5 to 10 m / s, more preferably 1 to 5 m / s, and even more preferably 2 to 3 m / s. The air velocity is the air velocity near the surface of the recording medium. When the air velocity is above the above range, image quality and reduction of head condensation are more excellent, which is preferable. When the air velocity is below the above range, clogging recovery is more excellent, which is preferable. The temperature of the air blower is preferably 50°C or lower, and more preferably 10°C or higher, more preferably 15 to 45°C, and even more preferably 20 to 49°C.

[0149] The heating in the primary heating step may be carried out at least one of before the ink application step, simultaneously with the application, and shortly after the application, and is preferably carried out simultaneously. The ink application step can be carried out in such a heating order. The heating temperature in the primary heating step is the surface temperature of the recording medium when ink is applied to the heated recording medium, or the surface temperature of the recording medium when heating is performed soon after ink application. It is also the maximum temperature during heating in the primary heating step. The surface temperature of the recording medium in the primary heating step may be in the range of the temperature described above as the surface temperature of the recording medium when the ink-jet ink composition is applied to the recording medium, and is preferably in the range of the temperature described above as the surface temperature of the recording medium when the ink-jet ink composition is applied to the recording medium. It's nice.

[0150] 2.3 Treatment liquid application process The recording method according to this embodiment may include a step of applying a treatment liquid containing a flocculant to the recording medium (treatment liquid application step). By including such a step, a pinning effect caused by a reaction between the treatment liquid and the ink composition can be achieved, resulting in better image quality (reduced aggregation unevenness).

[0151] The method of applying the treatment liquid to the recording medium may be any of non-contact and contact methods, such as an inkjet method, a coating method, a method of applying the treatment liquid to the recording medium using various sprays, a method of applying the treatment liquid by immersing the recording medium in the treatment liquid, or a method of applying the treatment liquid to the recording medium using a brush or the like, or a combination of these methods.

[0152] The treatment liquid application step may be carried out, for example, by ejecting the treatment liquid from an inkjet head 2 using an inkjet recording apparatus 1 as shown in Fig. 1. This is more preferable because it allows the treatment liquid and the inkjet ink composition to be applied to the recording medium using a single inkjet recording apparatus.

[0153] The treatment liquid application step may be performed before or after the application of the ink composition, or simultaneously with the application of the ink composition. When the treatment liquid is applied before or simultaneously with the application of the ink composition, it is preferable to heat the recording medium using a preheater 7 as shown in FIG. 1 before the treatment liquid application step, or using an IR heater 3 or platen heater 4 during the treatment liquid application step. By applying the treatment liquid to a heated recording medium, the treatment liquid ejected onto the recording medium can be more easily spread across the recording medium, potentially enabling a more uniform application of the treatment liquid. This tends to result in a sufficient reaction between the ink composition and the treatment liquid applied in the ink application step described above, resulting in superior image quality. Furthermore, because the treatment liquid is applied uniformly on the recording medium M, the amount of application can be reduced, potentially preventing a decrease in the abrasion resistance of the resulting image.

[0154] The amount of treatment liquid applied is 0.1 to 5 mg / inch per unit area of ​​the recording area of ​​the recording medium. 2 It is preferable that the density is 0.3 to 4 mg / inch. 2 More preferably, it is 0.5 to 3 mg / inch. 2 More preferably, it is 0.7 to 1.5 mg / inch. 2 It is particularly preferable that the maximum amount of treatment liquid applied per unit area of ​​the recording region of the recording medium during recording be within the above range. While the use of a treatment liquid can easily provide excellent image quality (aggregation unevenness), if the amount of the treatment liquid applied is large, it can have adverse effects such as poor abrasion resistance. In contrast, the inkjet ink composition containing the specific component used in the recording method according to this embodiment can provide excellent image quality (aggregation unevenness) due to the pinning effect of the ink itself. Therefore, by setting the amount of the treatment liquid applied within the above range, excellent abrasion resistance can be ensured and even better image quality (aggregation unevenness) can be obtained.

[0155] Each component contained in the treatment liquid will be described below.

[0156] <Processing liquid> The treatment liquid contains a flocculant.

[0157] [Flocculant] The flocculant acts on the dispersibility of components such as resins and pigments contained in the inkjet ink composition, thereby flocculating at least one of these dispersed components. The degree of aggregation of the resulting dispersion varies depending on the type of aggregating agent and the target, and can be adjusted. Such aggregation can, for example, improve the color development of the image and / or improve the fixability of the image.

[0158] The flocculant is not particularly limited, but examples thereof include metal salts, acids, cationic compounds, etc., and examples of cationic compounds that can be used include cationic resins (cationic polymers), cationic surfactants, etc. Among these, polyvalent metal salts are preferred as metal salts, and cationic resins are preferred as cationic compounds. Examples of acids include organic acids and inorganic acids, with organic acids being preferred. Therefore, it is preferred that the flocculant be selected from cationic resins, organic acids, and polyvalent metal salts, as this will result in particularly excellent image quality, abrasion resistance, gloss, etc.

[0159] (metal salts) The metal salt is preferably a polyvalent metal salt, but metal salts other than polyvalent metal salts can also be used. Among these flocculants, it is preferable to use at least one selected from metal salts and organic acids because of their excellent reactivity with the components contained in the ink. Furthermore, among cationic compounds, it is preferable to use cationic resins because they are easily soluble in the treatment liquid. Furthermore, it is also possible to use multiple types of flocculants in combination.

[0160] Polyvalent metal salts are compounds composed of divalent or higher metal ions and anions. Examples of divalent or higher metal ions include calcium, magnesium, copper, nickel, zinc, barium, aluminum, titanium, strontium, chromium, cobalt, and iron ions. Among the metal ions that compose these polyvalent metal salts, at least one of calcium ions and magnesium ions is preferred because they have excellent coagulation properties for ink components.

[0161] The anions constituting the polyvalent metal salt are inorganic or organic ions. That is, the polyvalent metal salt in the present invention is composed of an inorganic or organic ion and a polyvalent metal. Examples of such inorganic ions include chloride ions, bromide ions, iodide ions, nitrate ions, sulfate ions, and hydroxide ions. Examples of organic ions include organic acid ions, such as carboxylate ions.

[0162] The polyvalent metal compound is preferably an ionic polyvalent metal salt, and in particular, when the polyvalent metal salt is a magnesium salt or a calcium salt, the stability of the treatment solution is improved. The counter ion of the polyvalent metal may be either an inorganic acid ion or an organic acid ion.

[0163] Specific examples of the polyvalent metal salt include calcium carbonate, such as heavy calcium carbonate and light calcium carbonate, calcium nitrate, calcium chloride, calcium sulfate, magnesium sulfate, calcium hydroxide, magnesium chloride, magnesium carbonate, barium sulfate, barium chloride, zinc carbonate, zinc sulfide, aluminum silicate, calcium silicate, magnesium silicate, copper nitrate, calcium acetate, magnesium acetate, aluminum acetate, calcium propionate, magnesium propionate, aluminum propionate, calcium lactate, magnesium lactate, and aluminum lactate. These polyvalent metal salts may be used alone or in combination. Among these, at least one of magnesium sulfate, calcium nitrate, aluminum lactate, and calcium propionate is preferred in terms of achieving sufficient solubility in water. These metal salts may contain water of hydration in their raw material form.

[0164] Examples of metal salts other than polyvalent metal salts include monovalent metal salts such as sodium salts and potassium salts, such as sodium sulfate and potassium sulfate.

[0165] (acid) Suitable examples of organic acids include poly(meth)acrylic acid, formic acid, acetic acid, propionic acid, glycolic acid, oxalic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, citric acid, tartaric acid, lactic acid, pyruvic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, nicotinic acid, or derivatives of these compounds, or salts thereof. One organic acid may be used alone, or two or more organic acids may be used in combination. Metal salts of organic or inorganic acids are included in the above-mentioned metal salts.

[0166] Examples of inorganic acids include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, etc. The inorganic acids may be used alone or in combination of two or more.

[0167] (cationic compounds) Examples of cationic resins (cationic polymers) include cationic urethane resins, cationic olefin resins, cationic amine resins, and cationic surfactants.

[0168] As the cationic urethane-based resin, commercially available products can be used, such as Hydran CP-7010, CP-7020, CP-7030, CP-7040, CP-7050, CP-7060, and CP-7610 (trade names, manufactured by Dainippon Ink and Chemicals, Inc.), Superflex 600, 610, 620, 630, 640, and 650 (trade names, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and Urethane Emulsion WBR-2120C and WBR-2122C (trade names, manufactured by Taisei Fine Chemical Co., Ltd.).

[0169] The cationic olefin resin has an olefin such as ethylene or propylene in its structural skeleton, and known resins can be appropriately selected and used. The cationic olefin resin may also be in an emulsion state dispersed in a solvent containing water or an organic solvent. Commercially available cationic olefin resins can be used, such as Arrowbase CB-1200 and CD-1200 (trade names, manufactured by Unitika Ltd.).

[0170] The cationic amine resin (cationic polymer) may be any resin having an amino group in its structure, and known resins may be appropriately selected and used. Examples include polyamine resins, polyamide resins, and polyallylamine resins. Polyamine resins are resins having amino groups in their main skeletons. Polyamide resins are resins having amide groups in their main skeletons. Polyallylamine resins are resins having a structure derived from allyl groups in their main skeletons.

[0171] Examples of cationic polyamine resins include Unisense KHE103L (hexamethylenediamine / epichlorohydrin resin, 1% aqueous solution with a pH of approximately 5.0, a viscosity of 20 to 50 (mPa·s), and a solids concentration of 50% by mass) and Unisense KHE104L (dimethylamine / epichlorohydrin resin, 1% aqueous solution with a pH of approximately 7.0, a viscosity of 1 to 10 (mPa·s), and a solids concentration of 20% by mass), both manufactured by Senka Corporation. Specific examples of commercially available cationic polyamine resins include FL-14 (manufactured by SNF Co., Ltd.), Arafix 100, 251S, 255, 255LOX (manufactured by Arakawa Chemical Co., Ltd.), DK-6810, 6853, 6885; WS-4010, 4011, 4020, 4024, 4027, 4030 (manufactured by Seiko PMC Co., Ltd.), Papiogen P-105 (manufactured by Senka Co., Ltd.), Sumirez Resin 650 (30), 675A, 6615, SLX-1 (manufactured by Taoka Chemical Co., Ltd.), Catiomaster (registered trademark) PD-1, 7, 30, A, PDT-2, PE-10, PE-3 0, DT-EH, EPA-SK01, TMHMDA-E (manufactured by Yokkaichi Synthetic Co., Ltd.), Jetfix 36N, 38A, 5052 (manufactured by Satoda Chemical Co., Ltd.).

[0172] Examples of polyallylamine resins include polyallylamine hydrochloride, polyallylamine amidosulfate, allylamine hydrochloride-diallylamine hydrochloride copolymer, allylamine acetate-diallylamine acetate copolymer, allylamine acetate-diallylamine acetate copolymer, allylamine hydrochloride-dimethylallylamine hydrochloride copolymer, allylamine-dimethylallylamine copolymer, polydiallylamine hydrochloride, polymethyldiallylamine hydrochloride, polymethyldiallylamine amidosulfate, polymethyldiallylamine acetate, polydiallyldimethylammonium chloride, diallylamine acetate-sulfur dioxide copolymer, diallylmethylethylammonium ethyl sulfate-sulfur dioxide copolymer, methyldiallylamine hydrochloride-sulfur dioxide copolymer, diallyldimethylammonium chloride-sulfur dioxide copolymer, and diallyldimethylammonium chloride-acrylamide copolymer.

[0173] Examples of cationic surfactants include primary, secondary, and tertiary amine salt compounds, alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalkonium salts, quaternary ammonium salts, quaternary alkylammonium salts, alkylpyridinium salts, sulfonium salts, phosphonium salts, onium salts, and imidazolinium salts. Specific examples include hydrochlorides and acetates of laurylamine, coconut amine, and rosinamine, lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, benzyltributylammonium chloride, benzalkonium chloride, dimethylethyllaurylammonium ethyl sulfate, dimethylethyloctylammonium ethyl sulfate, trimethyllaurylammonium hydrochloride, cetylpyridinium chloride, cetylpyridinium bromide, dihydroxyethyllaurylamine, decyldimethylbenzylammonium chloride, dodecyldimethylbenzylammonium chloride, tetradecyldimethylammonium chloride, hexadecyldimethylammonium chloride, and octadecyldimethylammonium chloride. The cationic surfactant functions as an aggregating agent, which will be described later, and may be contained in the inkjet ink composition. However, it is more preferable that the cationic surfactant be contained as an aggregating agent in the treatment liquid.

[0174] A plurality of types of these flocculants may be used. Furthermore, if at least one of polyvalent metal salts, organic acids, and cationic resins is selected from these flocculants, the flocculating action is more favorable, and therefore images of higher quality (especially with better color development) can be formed.

[0175] The total content of the aggregating agent in the treatment liquid is, for example, 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 15% by mass or less, relative to the total mass of the treatment liquid. Even when the aggregating agent is used in both a solution and a dispersion, the solids content is preferably within the above range. A content of the aggregating agent of 1% by mass or more ensures that the aggregating agent has sufficient ability to aggregate the components contained in the ink. Furthermore, a content of the aggregating agent of 30% by mass or less improves the solubility and dispersibility of the aggregating agent in the treatment liquid, thereby improving the storage stability of the treatment liquid.

[0176] Furthermore, even if the organic solvent that may be contained in the treatment liquid is highly hydrophobic, the solubility of the flocculant in the treatment liquid will be good, so it is preferable to use a flocculant with a solubility of 1 g or more in 100 g of water at 25°C, and it is more preferable to use a flocculant with a solubility of 3 g or more and 80 g or less.

[0177] [Specific low molecular weight organic compounds and specific diols] The processing liquid has a melting point of 30°C or higher and is one of amides, sulfur-containing compounds, and cyclic ethers. and an organic solvent that is a diol having a melting point of 25° C. or lower (specific diols). The specific low-molecular-weight organic compound has the resin-solubility to swell and dissolve the resin contained in the ink and the low-absorbency or non-absorbency recording medium, thereby providing excellent abrasion resistance. Furthermore, by including the specific diol, it is easy to adjust the ejection characteristics to an appropriate level.

[0178] The specific low-molecular-weight organic compound and the specific diols are the same as those in the ink-jet ink composition described above, and therefore a description thereof will be omitted. The contents and content ratios thereof can also be, and preferably are, the same as those in the ink-jet ink composition described above.

[0179] [Other ingredients] In addition to the above components, the treatment liquid may contain components such as resin, water, organic solvents other than the specific diols, wax, antifoaming agents, surfactants, alkanolamines, additives, preservatives, antifungal agents, rust inhibitors, chelating agents, antioxidants, and antifungal agents, as long as the functionality is not impaired. These components are the same as those in the inkjet ink composition described above, so detailed description will be omitted. The treatment liquid is preferably a water-based treatment liquid.

[0180] The treatment liquid is obtained by mixing the above-mentioned components in an appropriate order and, if necessary, removing impurities by filtration, etc. As a method for mixing the components, a method in which the materials are added to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirred and mixed is preferably used.

[0181] 2.4 Post-heating process The recording method according to this embodiment may include a post-heating step of heating the recording medium to which the inkjet ink composition has been applied. This is preferable because it tends to improve the drying property and provide a recorded product with better abrasion resistance.

[0182] The post-heating step is a heating step in which the recording is completed and the recording material is heated sufficiently to be usable. The post-heating step is a heating step in which the solvent component of the ink is sufficiently dried and the resin contained in the ink is heated to form a flat 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 the ink has been completely applied to that area. Furthermore, it is preferable that the temperature preferred in the primary heating step is different from the temperature preferred in the post-heating step.

[0183] The heating of the recording medium in the post-heating step can be performed using an appropriate heating means, for example, when an inkjet recording apparatus is used, or by any appropriate heating means, not limited to the heating means provided in the inkjet recording apparatus. The lower limit of the surface temperature of the recording medium in the post-heating step is preferably 50° C. or higher, more preferably 60° C. or higher, even more preferably 70° C. or higher, and particularly preferably 75° C. or higher. The upper limit is preferably 120° C. or lower, more preferably 110° C. or lower, even more preferably 100° C. or lower, and particularly preferably 90° C. or lower.

[0184] 2.5 Inkjet recording device An example of an inkjet recording apparatus suitable for the recording method according to this embodiment will be described with reference to the drawings. The inkjet recording apparatus includes an inkjet head that performs an ink deposition process of the inkjet ink composition, and a primary heating mechanism. This can be done.

[0185] 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.

[0186] The inkjet head 2 is configured to perform recording on the recording medium M by ejecting and depositing the treatment liquid and inkjet ink composition from the nozzles of the inkjet head 2. In this embodiment, the inkjet head 2 is a serial type inkjet head, and deposits the ink on the recording medium M by scanning multiple times in the main scanning direction relative to 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.

[0187] Here, the main scanning direction is the direction in which the carriage 9 carrying the inkjet head 2 moves. In FIG. 1, this direction intersects with 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 the main scanning direction, i.e., in either the direction indicated by the arrow S1 or the arrow S2, in one scan. Recording is performed on the recording medium M by repeating the main scan of the inkjet head 2 and the sub-scan, which transports the recording medium M, multiple times. In other words, the treatment liquid application process and the ink application process are performed by multiple main scans in which the inkjet head 2 moves in the main scanning direction, and multiple sub-scans in which the recording medium M moves in the sub-scanning direction that intersects the main scanning direction.

[0188] The cartridges 12 that supply the inkjet ink composition and treatment liquid to the inkjet head 2 respectively 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 is filled with a different type of inkjet ink composition or treatment liquid, and the inkjet ink composition and treatment liquid are supplied from the cartridges 12 to each nozzle. Note that in this embodiment, an example is shown in which the cartridge 12 is mounted on the carriage 9, but this is not limiting, and the cartridge 12 may be provided in a location other than the carriage 9 and may supply the ink to each nozzle via a supply pipe (not shown).

[0189] A conventionally known method can be used for ejection from the inkjet head 2. In this embodiment, 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.

[0190] The inkjet recording apparatus 1 is equipped with an IR heater 3 and a platen heater 4 for heating the recording medium M when the inkjet ink composition is ejected from the inkjet head 2. A primary heating step can be performed by the IR heater 3 or the platen heater 4. Furthermore, in this embodiment, when drying the recording medium M in the primary heating step, a ventilation fan 8, which will be described later, or the like can be used.

[0191] Note that by using the IR heater 3, 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. Also, various 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.

[0192] The platen heater 4 heats the recording medium M via the platen 11 at a position facing the inkjet head 2 so that the treatment liquid and inkjet ink composition ejected by the inkjet head 2 can be dried quickly from the moment they are applied to the recording medium M. The platen heater 4 is capable of conductively heating the recording medium M, and in the recording method of this embodiment, the inkjet ink composition can be applied to the heated recording medium M (primary heating). This allows the inkjet ink composition to be fixed quickly on the recording medium M, improving image quality.

[0193] The heater 5 dries and solidifies the treatment liquid or inkjet ink composition applied to the recording medium M, i.e., it is a heater for secondary heating or secondary drying. The heater 5 can be used in a post-heating step. When the heater 5 heats the recording medium M on which an image has been recorded, the moisture and other components contained in the inkjet ink composition evaporate and dissipate more quickly, and an ink film is formed by the resin contained in the inkjet ink composition. 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 period of time.

[0194] The inkjet recording apparatus 1 may have a cooling fan 6. After the inkjet ink composition recorded on the recording medium M has dried, the inkjet ink composition 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.

[0195] The inkjet recording apparatus 1 may also include a preheater 7 that preheats the recording medium M before the inkjet ink composition is applied to the recording medium M. Furthermore, the inkjet recording apparatus 1 may also include a ventilation fan 8 so that the inkjet ink composition applied to the recording medium M can dry more efficiently.

[0196] 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.

[0197] FIG. 3 is a functional block diagram of the inkjet recording apparatus 1. The control unit CONT is a control unit for controlling the inkjet recording apparatus 1. The interface unit 101 (I / F) is for sending and receiving data between the computer 130 (COMP) and the inkjet recording apparatus 1. The CPU 102 is an arithmetic processing unit for controlling the entire inkjet recording apparatus 1. The memory 103 (MEM) is for securing an area for storing programs for the CPU 102, a working area, etc. The CPU 102 controls each unit via a unit control circuit 104 (UCTRL). The detector group 121 (DS) monitors the status inside the inkjet recording apparatus 1, and the control unit CONT controls each unit based on the detection results.

[0198] The transport unit 111 (CONVU) controls the sub-scanning (transport) of inkjet recording. Specifically, it controls the transport direction and transport speed of the recording medium M. Specifically, it controls the transport direction and transport speed of the recording medium M by controlling the rotation direction and rotation speed of a transport roller driven by a motor.

[0199] The carriage unit 112 (CARU) controls the main scan (pass) of inkjet recording, and more specifically, moves the inkjet head 2 back and forth in the main scan direction. The carriage unit 112 includes a carriage 9 on which the inkjet head 2 is mounted, and a carriage movement mechanism 13 for moving the carriage 9 back and forth.

[0200] The head unit 113 (HU) controls the amount of inkjet ink composition and treatment liquid ejected from the nozzles of the inkjet head 2. For example, if the nozzles of the inkjet head 2 are driven by piezoelectric elements, the head unit 113 controls the operation of the piezoelectric elements in each nozzle. The head unit 113 controls the timing of deposition of each ink and treatment liquid, the dot size of the inkjet ink composition and treatment liquid, etc. Furthermore, the amount of inkjet ink composition and treatment liquid deposited per scan is controlled by a combination of controls of the carriage unit 112 and the head unit 113.

[0201] The drying unit 114 (DU) controls the temperatures of various heaters such as the IR heater 3, the preheater 7, the platen heater 4, and the heating heater 5.

[0202] The inkjet recording apparatus 1 alternately repeats an operation of moving the carriage 9 carrying the inkjet head 2 in the main scanning direction and a transport operation (sub-scanning). During each pass, the control unit CONT controls the carriage unit 112 to move the inkjet head 2 in the main scanning direction, and controls the head unit 113 to eject droplets of the inkjet ink composition from predetermined nozzle holes in the inkjet head 2, causing the droplets of the inkjet ink composition to adhere to the recording medium M. The control unit CONT also controls the transport unit 111 to transport the recording medium M in the transport direction by a predetermined transport amount (feed amount) during the transport operation.

[0203] In the inkjet recording device 1, the recording area onto which multiple droplets have been deposited is gradually transported by repeating main scanning (passes) and sub-scanning (transportation operations). Then, the droplets deposited on the recording medium M are dried by an after-heater 5, completing the image. Thereafter, the completed recording may be wound into a roll by a winding mechanism, or transported by a flatbed mechanism.

[0204] 4 is an example of a flowchart showing the processing performed when recording in an inkjet recording device. When starting recording, the control unit of the inkjet recording device determines the recording mode in step S400. The recording mode is a recording mode that defines details of recording, such as nozzle arrangement, ejection volume, overlapping mode, inkjet head operation during recording, recording medium operation, and control of the heating mechanism. The details of recording also include the number of recording passes (the number of times main scanning is performed on the same recording area on the recording medium).

[0205] The print mode is determined by an input signal input to the inkjet printing device from an external device such as a computer, or by information input by a user to a user input unit provided in the inkjet printing device. Here, the input signal from the external device or the information input by the user may be information that directly specifies the print mode, or may be information related to printing, such as information on the type of recording medium to be printed, a print speed specification, or an image quality specification. The information related to printing is not limited to these. In the latter case, the inkjet printing device stores correspondence information in advance in the inkjet printing device, such as a control unit, that defines the print mode corresponding to the information related to printing, and determines the print mode by referring to the correspondence information. Alternatively, the decision may be made using AI technology (artificial intelligence technology).

[0206] In step S401, the determined print mode is identified. In step S402 or S403, the number of passes corresponding to the determined print mode is set according to the print mode. In step S404, printing is performed. Although two print modes, a first print mode and a second print mode, are shown in the figure, there may be three or more print modes.

[0207] In this example, the printing apparatus can vary the number of printing passes (the number of times main scanning is performed on the same printing area of ​​the printing medium) depending on the printing mode, which is preferable because it can perform a variety of printing operations.

[0208] 1 and 2, a serial type inkjet recording device is shown, but a line type inkjet recording device can also be used. The inkjet recording apparatus exemplified above can be suitably applied to the recording method of this embodiment.

[0209] 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.

[0210] 3.1 Preparation of Inkjet Ink Composition The components were placed in a container to obtain the compositions shown in Tables 1 and 2 below, mixed and stirred for 2 hours using a magnetic stirrer, and then filtered through a membrane filter with a pore size of 5 μm to obtain inkjet ink compositions according to Examples and Comparative Examples. All values ​​in Tables 1 and 2 below indicate mass %, and pure water was added so that the total mass of the inkjet ink composition was 100 mass %. The pigment dispersion and resin used were prepared in advance as described below. The values ​​in the tables for the pigment dispersion and resin indicate the amount of active ingredient (equivalent to solid content).

[0211] [Preparation of pigment dispersion] A flask equipped with a dropping funnel, nitrogen inlet, reflux condenser, thermometer, and stirrer was charged with 50 g of methyl ethyl ketone (MEK) and 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 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 mass aqueous sodium hydroxide solution was added as a neutralizing agent to neutralize 100% of the salt-forming groups, and 50 g of pigment (carbon black) was added little by little while stirring, followed by kneading for 2 hours in a bead mill. 200 g of ion-exchanged water was added to the resulting kneaded product, and after stirring, the mixture was heated under reduced pressure to distill off the MEK. The concentration was further adjusted with ion-exchanged water to obtain a pigment dispersion (pigment solids: 20% by mass, resin solids: 5% by weight). The particle diameter (D50) was measured using a Nanotrac Wave II EX-150 (manufactured by Microtrack Bell Co., Ltd.) and found to be 110 nm.

[0212] [Preparation of Resin] A reaction vessel equipped with a stirrer, reflux condenser, dropping device, and thermometer was charged with 2600 g of ion-exchanged water and 0.5 g of sodium lauryl sulfate, and the temperature was raised to 70°C while stirring and replacing with nitrogen. The internal temperature was kept at 70°C, and 4 g of potassium persulfate was added as a polymerization initiator. After dissolution, 300 g of ion-exchanged water, 0.5 g of sodium lauryl sulfate, and acrylic acid solution were added. An emulsion was prepared by adding 180 g of methyl methacrylate, 35 g of butyl methacrylate, and 5 g of methacrylic acid to 2 g of methacrylate under stirring, and the emulsion was continuously added dropwise to the reaction solution over a period of 3 hours. After the dropwise addition, the mixture was aged for 1 hour. After the aging, an emulsion was prepared by adding 500 g of ion-exchanged water, 1.5 g of sodium lauryl sulfate, 30 g of acrylamide, 850 g of styrene, 750 g of methyl methacrylate, 50 g of 2-ethylhexyl methacrylate, and 40 g of methacrylic acid under stirring. The emulsion was then added dropwise to the reaction solution over 4 hours. After the dropwise addition, the mixture was aged for 3 hours. The resulting aqueous emulsion (acid value 15 mg / KOH, Tg 90°C) was cooled to room temperature, and then ion-exchanged water and aqueous sodium hydroxide were added to adjust the solid content to 30% by weight and the pH to 8, producing Resin A. The resulting particles had a sea-island structure. The particle diameter (D50) was measured using a Nanotrac Wave II EX-150 (Microtrack Bell Co., Ltd.) and was found to be 140 nm. Resins B to D were similarly produced, controlling the Tg and particle diameter by adjusting the monomer ratio and the stirring speed during the reaction. The Tg and particle diameter of each resin prepared will be described below.

[0213] 3.2 Preparation of processing solution The components were placed in a container to obtain the composition shown in Table 3 below, mixed and stirred for 2 hours using a magnetic stirrer, and then filtered through a membrane filter with a pore size of 5 μm to obtain a treatment solution according to the example. All values ​​in Table 3 below indicate mass %, and pure water was added so that the total mass of the treatment solution was 100 mass %. The values ​​in the table for cationic resins indicate the amount of active ingredient (equivalent to solid content).

[0214] [Table 1]

[0215] [Table 2]

[0216] [Table 3]

[0217] The following provides additional explanations for the descriptions in Tables 1 to 3 above. <Terminology> "Specific low molecular weight organic compounds": Water-soluble low molecular weight organic compounds with a melting point of 30°C or higher, which are either amides, sulfur-containing compounds, or cyclic ethers. "Specific diols": organic solvents that are diols with a melting point of 25°C or less "Particle size ratio (B / A)": The ratio of the volume average particle size B of the resin to the volume average particle size A of the black pigment (B / A) "Boiling point": Indicates the standard boiling point

[0218] <Ingredients> -Specified low molecular weight organic compounds- "CPL": ε-caprolactam "2Pi": 2-piperidone "AA": Acetoacetamide "DMS": dimethyl sulfone "DOXD": 1,4-dioxane-2,3-diol -Other low molecular weight organic compounds- "2P": 2-pyrrolidone "DMPA": 3-methoxy-N,N-dimethylpropanamide -Specific diols- "1,2HD": 1,2-hexanediol "PG": Propylene glycol "DPG": Dipropylene glycol -Other diols- "NPG": Neopentyl glycol -resin- "Resin A": Resin emulsion, styrene acrylic resin, Tg: 90°C, volume average particle size: 140 nm "Resin B": Resin emulsion, styrene acrylic resin, Tg: 70°C, volume average particle size: 140 nm "Resin C": Resin emulsion, styrene acrylic resin, Tg: 90°C, volume average particle size: 100 nm "Resin D": Resin emulsion, styrene acrylic resin, Tg: 90°C, volume average particle size: 180nm -wax- "Hi-Tech E-6500": Wax emulsion, polyethylene wax, product name manufactured by Toho Chemical Industry Co., Ltd. -Antifoaming agent- "Surfynol DF110D": Acetylenic surfactant, product name manufactured by Nissin Chemical Industry Co., Ltd. -Surfactants- "BYK333": Silicone surfactant, product name manufactured by BYK Japan Co., Ltd. -Alkanolamines- "TIPA": Triisopropanolamine, alkanolamines -Flocculant- "Catiomaster PD-7": Amine-epichlorohydrin copolymer, product name manufactured by Yokkaichi Synthetic Co., Ltd.

[0219] 3.3 Recording conditions The recording conditions in the evaluation test were as follows. [Recording conditions] Printing machine: "SC-R5050", manufactured by Seiko Epson Corporation. Modified model. Resolution: 1200 x 1200 dpi Amount of adhesion: Inkjet ink composition (12 mg / inch 2 ), processing solution (if present, 1 mg / inch 2 ) Printing pattern: Solid pattern (black only) Number of passes: The number of passes listed in Table 4 below Paper surface temperature: Temperatures listed in Table 4 below (heater OFF for 25°C) Wind speed on paper: Wind speed directly above the recording medium near the head. Values ​​in Table 4. Main scanning time: The time it takes for one point of the head to move from one edge of the recording medium to the other in the main scanning. Surface temperature of recording medium in post-heating process: 80° C. Post-heating was performed using a heater for the post-heating process that was installed downstream in the conveyance direction of the recording medium. Recording medium: "Orajet 3165G-010", product name of Orafor Japan, PVC film Platen gap: 1.7mm

[0220] Under the above printing conditions, the paper surface temperature is the surface temperature of the recording medium during the primary heating process. A platen heater was used for the primary heating. In addition, air was blown near the surface of the recording medium by a fan installed above the head. The air temperature was set to 25°C. The example of a paper surface temperature of 25° C. indicates the surface temperature of the recording medium during the ink deposition process when the heater is turned off and no heating is performed. In addition, in Table 4 below, "number of passes" refers to the number of times main scanning was performed on the same main scanning area. In the head of the recording device, the nozzle row provided on the upstream side in the recording medium conveyance direction was filled with the treatment liquid, and the nozzle row provided on the downstream side was filled with the ink liquid. Recording was carried out under the above recording conditions.

[0221] [Table 4]

[0222] 3.4 Evaluation method The evaluation items were storage stability, image quality (uneven gloss banding), image quality (uneven aggregation), landing misalignment, clogging recovery, head condensation, and drying (abrasion resistance). The evaluation methods were as follows:

[0223] 3.4.1 Storage stability 30 g of each color ink used in the examples and comparative examples was sealed in an aluminum pack to prevent air bubbles from being mixed in, and then left in a thermostatic chamber at 60°C for 6 days. After being taken out and allowed to cool naturally, the ink was measured at a shear rate of 200 s using a rheometer (MCR702 / Anton Paar). -1 The viscosity of the ink was measured and compared with the initial viscosity (immediately after preparation of the ink) to calculate the viscosity increase rate, and the ink was evaluated according to the following criteria. 〔Judgment criteria〕 A: Viscosity increase rate less than 3% B: Viscosity increase rate 3% or more, less than 5% C: Viscosity increase rate 5% or more (NG)

[0224] 3.4.2 Image Quality (Gloss Banding) Under the above recording conditions, a solid pattern was printed according to Table 4. The printed matter was visually observed and evaluated according to the following criteria. 〔Judgment criteria〕 AA: Band-like gloss unevenness (gloss banding) extending in the main scanning direction with different gloss is not visible. A: Glossy banding is visible, but not noticeable. B: Gloss banding is noticeable but acceptable C: Noticeable gloss banding

[0225] 3.4.3 Image quality (aggregation unevenness) Under the above recording conditions, a solid pattern was printed according to Table 4, and the printed matter was visually observed and evaluated according to the following criteria. 〔Judgment criteria〕 AA: No uneven aggregation A: There is some unevenness in aggregation, but it is not noticeable. B: Uneven aggregation is noticeable, but acceptable C: Uneven aggregation is noticeable

[0226] 3.4.4 Missing bullets A recording device was prepared under the above recording conditions according to Table 4. First, a nozzle check pattern was recorded immediately after flushing. A one-minute idle run was performed under the printing conditions in Table 4 above without ejecting ink, and after the idle run, a similar nozzle check pattern was recorded. When recording the nozzle check pattern, ink was ejected at a timing that would ensure the landing position would be the same before and after the idle run, provided that there was no deviation in the landing position. The average value for all nozzles was calculated, excluding non-ejecting nozzles. Evaluation was carried out according to the following criteria. 〔Judgment criteria〕 AA: No difference in impact position before and after air transport A: Misalignment within half the distance between nozzles B: There is a deviation within the distance between nozzles C: There is a misalignment beyond the nozzle distance

[0227] 3.4.5 Clogging recovery Under the above recording conditions, a recording device was prepared according to Table 4. Non-ejection was caused. In this state, the printer was allowed to idle for two hours under the printing conditions in Table 4 above. After printing, cleaning was performed three times, and finally, the number of missing nozzles was determined and evaluated according to the following criteria. In one cleaning, 0.5g of ink was discharged from the nozzle row. Non-ejection of the nozzles was caused by hitting the nozzle surface with a Bemcot dampened with water. The nozzle row consists of 400 nozzles. 〔Judgment criteria〕 AA: No non-ejecting nozzles A: Less than 3% of nozzles are non-ejecting B: Non-ejecting nozzles: 3% to less than 5% C: 5% or more non-ejecting nozzles

[0228] 3.4.6 Condensation on the head Under the above recording conditions, a solid pattern was continuously printed for 2 hours / 4 hours according to Table 4, and the occurrence of condensation and non-ejecting nozzles was confirmed. Printing was carried out in a constant temperature and humidity room at 25°C and 20%. After printing, the nozzle surface of the print head was checked for condensation and the presence of non-ejecting nozzles, and the results were evaluated according to the following criteria. 〔Judgment criteria〕 AA: No condensation on the nozzle surface even after 4 hours of printing A: After 4 hours of printing, condensation occurs on the nozzle surface, but it does not lead to non-ejecting nozzles. B: After 4 hours of printing, condensation occurred on the nozzle surface, resulting in non-ejecting nozzles. C: After 2 hours of printing, condensation occurred on the nozzle surface, resulting in non-ejecting nozzles.

[0229] 3.4.7 Drying property (abrasion resistance) Under the above recording conditions, a solid pattern was recorded on the recording medium according to Table 4. After recording, the recording medium was left at room temperature for 30 minutes, and the solid pattern printed area was cut into a 30 x 150 mm rectangle. The area was rubbed 100 times with a plain woven cloth using a Gakushin abrasion resistance tester (load 500 g), and the degree of ink peeling was visually evaluated according to the following criteria. 〔Judgment 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

[0230] 3.5 Evaluation Results The evaluation results are shown in Tables 1 to 2 and Table 4 above.

[0231] Comparison of the Examples and Comparative Examples reveals that the inkjet ink composition and recording method according to this embodiment all provide excellent abrasion resistance, image quality (reduction of aggregation unevenness), and reduction of ink landing deviation. In contrast, all of the comparative examples that did not use the ink or recording method according to this embodiment were inferior in either rub resistance, image quality (reduction of aggregation unevenness), or reduction of landing deviation.

[0232] A comparison between Example 1 and Comparative Examples 1 to 9 reveals that by including a specific low-molecular-weight organic compound in an amount equal to or less than a predetermined amount and including a specific diol in an amount greater than the amount of the specific low-molecular-weight organic compound, it is possible to achieve excellent image quality (agglomeration unevenness) and abrasion resistance, as well as excellent reduction in impact misalignment.

[0233] The results of Examples 1, 3 to 5, and 13 show that a specific low-molecular organic compound, which is any one of amides, sulfur-containing compounds, and cyclic ethers, can provide excellent image quality (agglomeration unevenness) and excellent reduction in landing deviation.

[0234] The results of Examples 1, 2, and 6 to 7 show that, when the mass ratio (A / B) of the content A of the specific diol to the content B of the specific low-molecular-weight organic compound is within a predetermined wide range, it is possible to improve the impact misalignment, abrasion resistance, clogging recovery, and the like.

[0235] The results of Examples 1 and 8 show that specific diols can effectively reduce landing deviation, regardless of the combination.

[0236] The results of Examples 9 to 11 show that various types of resin can provide excellent abrasion resistance and image quality (aggregation unevenness), and can also effectively reduce landing deviation.

[0237] The results of Examples 1, 14 and 15 show that excellent image quality (aggregation unevenness) can be ensured even when the surface temperature of the recording medium at the time of ink attachment is relatively low.

[0238] The results of Examples 14 and 16 to 20 show that excellent image quality (aggregation unevenness) can be obtained even when no treatment liquid is used in combination.

[0239] The results of Examples 1, 21 and 22 show that even if conditions such as the main scanning time and the wind speed on the paper surface are appropriately changed, excellent image quality (agglomeration unevenness) and abrasion resistance can be achieved, and impact deviation can be reduced.

[0240] The results of Examples 1, 23 and 24 show that excellent image quality (aggregation unevenness) can be ensured even when the number of passes is relatively small.

[0241] The following can be derived from the above-described embodiment.

[0242] One embodiment of the inkjet ink composition comprises: Contains a pigment and a resin, A water-based ink for use in recording on a low-absorbency recording medium or a non-absorbency recording medium, the ink composition contains a water-soluble low-molecular-weight organic compound having a melting point of 30°C or higher and which is any one of an amide, a sulfur-containing compound, or a cyclic ether in an amount of 10% by mass or less relative to the total mass of the ink composition; The organic solvent is a diol having a melting point of 25° C. or less, and the content of the organic solvent is greater than the content of the low-molecular organic compound.

[0243] In one embodiment of the inkjet ink composition, The mass ratio (A / B) of the content A of the organic solvent which is a diol having a melting point of 25° C. or less to the content B of the low molecular weight organic compound may be 1.3 to 10.

[0244] In any of the above inkjet ink compositions, The content of the organic solvent, which is a diol having a melting point of 25° C. or less, may be 5 to 30% by mass relative to the total mass of the ink composition.

[0245] In any of the above inkjet ink compositions, The organic solvent which is a diol having a melting point of 25°C or less may contain an organic solvent having a normal boiling point of 170 to 250°C.

[0246] In any of the above inkjet ink compositions, The low molecular weight organic compound may have a normal boiling point of 280° C. or less.

[0247] In any of the above inkjet ink compositions, The resin may contain resin particles.

[0248] In any of the above inkjet ink compositions, The resin particles may have a glass transition point of 50 to 110° C. and a volume average particle diameter of 90 to 220 nm.

[0249] In any of the above inkjet ink compositions, The resin may be resin particles, and the ratio (B / A) of the volume average particle diameter B of the resin particles to the volume average particle diameter A of the pigment may be 0.6 to 1.8.

[0250] 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 onto a recording medium, wherein the recording medium is a low-absorbency recording medium or a non-absorbency recording medium.

[0251] In one aspect of the recording method, The surface temperature of the recording medium may be 45° C. or less when the ink-jet ink composition is applied to the recording medium.

[0252] In any one of the above recording methods, The method may further include a primary heating step of heating the inkjet ink composition attached to the recording medium.

[0253] In any one of the above recording methods, The method may include a step of applying a treatment liquid containing a flocculant to the recording medium.

[0254] In any one of the above recording methods, The treatment liquid may contain a water-soluble low-molecular-weight organic compound having a melting point of 30°C or higher and being any one of amides, sulfur-containing compounds, and cyclic ethers, and an organic solvent which is a diol having a melting point of 25°C or lower.

[0255] In any one of the above recording methods, The inkjet head may be ejected while performing a main scan multiple times to move the relative position between the recording medium and the inkjet head, and the number of main scans performed on the same main scan region may be 10 or less.

[0256] 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]

[0257] 1...inkjet recording device, 2...inkjet head, 3...IR heater, 4...platen heater, 5...heating heater, 6...cooling fan, 7...preheater, 8...ventilation fan, 9...carriage, 11...platen, 12...cartridge, 13...carriage moving mechanism, 14...transport means, 101...interface section, 102...CPU, 103...memory, 104...unit control circuit, 111...transport unit, 112...carriage unit, 11 3...head unit, 114...drying unit, 121...detector group, 130...computer, CONT...control unit, MS...main scanning direction, SS...sub-scanning direction, M...recording medium

Claims

1. A composition comprising a pigment and a resin, A water-based ink for use in recording on a low-absorbency recording medium or a non-absorbency recording medium, the ink composition contains a water-soluble low-molecular-weight organic compound having a melting point of 30°C or higher and which is any one of an amide, a sulfur-containing compound, or a cyclic ether in an amount of 10% by mass or less relative to the total mass of the ink composition; The organic solvent is a diol having a melting point of 25°C or less, and the content of the organic solvent is greater than the content of the low molecular weight organic compound. the resin comprises resin particles; The resin particles have a glass transition temperature of 50 to 110° C. and a volume average particle diameter of 90 to 220 nm.

2. A composition comprising a pigment and a resin, A water-based ink for use in recording on a low-absorbency recording medium or a non-absorbency recording medium, the ink composition contains a water-soluble low-molecular-weight organic compound having a melting point of 30°C or higher and which is any one of an amide, a sulfur-containing compound, or a cyclic ether in an amount of 10% by mass or less relative to the total mass of the ink composition; The organic solvent is a diol having a melting point of 25°C or less, and the content of the organic solvent is greater than the content of the low molecular weight organic compound. the resin comprises resin particles; the resin is resin particles, and a ratio (B / A) of a volume average particle diameter B of the resin particles to a volume average particle diameter A of the pigment is 0.6 to 1.

8.

3. 3. The inkjet ink composition according to claim 1, wherein a mass ratio (A / B) of a content A of the organic solvent that is a diol having a melting point of 25° C. or less to a content B of the low-molecular-weight organic compound is 1.3 to 10.

4. The content of the organic solvent which is a diol having a melting point of 25° C. or less is The ink-jet ink composition according to any one of claims 1 to 3, wherein the amount of the ink is 5 to 30% by mass.

5. 5. The ink-jet ink composition according to claim 1, wherein the organic solvent that is a diol and has a melting point of 25°C or less includes an organic solvent having a normal boiling point of 170 to 250°C.

6. The ink-jet ink composition according to claim 1 , wherein the low-molecular-weight organic compound has a normal boiling point of 280° C. or less.

7. 7. A recording method comprising a step of ejecting the inkjet ink composition according to claim 1 from an inkjet head and depositing it onto a recording medium, wherein the recording medium is a low-absorbency recording medium or a non-absorbency recording medium.

8. 8. The recording method according to claim 7, wherein the surface temperature of the recording medium is 45[deg.] C. or less when the ink-jet ink composition is applied to the recording medium.

9. The recording method according to claim 7 or 8, further comprising a primary heating step of heating the inkjet ink composition attached to the recording medium.

10. 10. The recording method according to claim 7, further comprising a step of applying a treatment liquid containing a coagulant to the recording medium.

11. 11. The recording method according to claim 10, wherein the processing liquid contains a water-soluble low-molecular-weight organic compound having a melting point of 30° C. or higher and being any one of amides, sulfur-containing compounds, and cyclic ethers, and an organic solvent which is a diol having a melting point of 25° C. or lower.

12. 12. The recording method according to claim 7, wherein a main scan is performed a plurality of times to move the relative position between the recording medium and the inkjet head while ejecting the inkjet ink composition from the inkjet head, and the number of main scans performed on the same main scan region is 10 or less.

Images