Water-based ink-jet ink composition

Abstract

To provide an aqueous ink-jet ink composition which can achieve both good fixability and good unclogging properties.SOLUTION: An aqueous ink-jet ink composition according to the present invention contains a pigment, water, resin particles, 1-(2-hydroxyethyl)-2-pyrrolidone, and trimethylglycine. The mass-based content of the resin particles is lower than the mass-based content of the pigment.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-based ink-jet ink composition. [Background technology]

[0002] Inkjet recording is a method of ejecting small droplets of ink from fine nozzles and depositing them on a recording medium to perform recording. This method is characterized by being capable of recording high-resolution, high-quality images at high speed using a relatively inexpensive device, and various studies have been conducted on the aqueous inkjet ink compositions used in this method.

[0003] In the past, in order to improve the fixation of a pigment as a colorant of the ink to a recording medium, it has been proposed to add resin particles to a water-based inkjet ink composition. For example, Patent Document 1 describes a water-based inkjet ink composition containing a pigment and resin particles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-156653 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in order to obtain good fixability, it is generally necessary to increase the content of resin particles. On the other hand, if the content of resin particles is increased, the resin particles tend to dry out and solidify in the nozzle, which causes a problem that clogging of the nozzle is difficult to recover even after cleaning, that is, the clogging recovery is poor. Therefore, it is required to achieve both good fixability and good clogging recovery. [Means for solving the problem]

[0006] One embodiment of the water-based inkjet ink composition according to the present invention comprises: Pigment, water, Resin particles; 1-(2-hydroxyethyl)-2-pyrrolidone, trimethylglycine, The content by mass of the resin particles is less than the content by mass of the pigment. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram illustrating a schematic diagram of an inkjet recording apparatus equipped with a line head. [Diagram 2] FIG. 2 is a plan view illustrating a line head. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described. The embodiment described below is an example of the present invention. The present invention is not limited to the following embodiment, and includes various modified forms that are implemented within the scope that does not change the gist of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

[0009] 1. Water-based ink-jet ink composition The water-based inkjet ink composition according to one embodiment of the present invention contains a pigment, water, resin particles, 1-(2-hydroxyethyl)-2-pyrrolidone, and trimethylglycine. The content by mass of the resin particles is less than the content by mass of the pigment.

[0010] According to the aqueous inkjet ink composition of this embodiment, by containing 1-(2-hydroxyethyl)-2-pyrrolidone (sometimes abbreviated as "HEP" in this specification), good fixability can be obtained even with a low content of resin particles relative to the pigment. In other words, by containing HEP, it is possible to reduce the content ratio of resin particles that cause nozzle clogging while maintaining good fixability. It is also presumed that HEP also has the effect of dissolving and redispersing the dried ink composition, making it easier to clean. Furthermore, it is presumed that the inclusion of trimethylglycine, which has excellent moisture retention properties, reduces the drying of the ink composition. These interactions have made it possible to achieve both good clogging recovery properties and good fixability.

[0011] Hereinafter, each component contained in the water-based inkjet ink composition according to this embodiment (hereinafter also referred to as the "ink composition") will be described.

[0012] 1.1.Pigments The aqueous inkjet ink composition according to this embodiment contains a pigment. Examples of the pigment include inorganic pigments and organic pigments. The hue of the pigment is not limited, and may be a so-called process color such as cyan, magenta, yellow, or black, or a so-called special color such as white, fluorescent color, or glitter color.

[0013] As the inorganic pigment, carbon blacks such as furnace black, lamp black, acetylene black, and channel black (CI Pigment Black 7), iron oxide, titanium oxide, zinc oxide, silica, and the like can be used.

[0014] 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 of carbon black include Cabot Corporation's Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, and Elftex 12. Examples of carbon black include Cabot Corporation's BONJET Examples include BLACK CW-1, CW-1S, CW-2, CW-3, and M-800.

[0015] 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.

[0016] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc.; CIVat 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.

[0017] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, CI Pigment Violet 19, and the like. Preferred examples include one or a mixture of two or more selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19.

[0018] 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, and 138.

[0019] 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.

[0020] The luster pigment is not particularly limited as long as it can exhibit luster when attached to a medium, and examples thereof 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 having a pearly luster. Representative examples of pearl pigments include pigments having a 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.

[0021] Examples of the white pigment include metal oxides, barium sulfate, calcium carbonate, and other metal compounds. Examples of the metal oxides include titanium dioxide, zinc oxide, silica, alumina, magnesium oxide, and other. The white pigment may be a particle having a hollow structure.

[0022] The above pigment is preferably added to the ink composition in the form of a pigment dispersion obtained by dispersing the pigment in water with a dispersant such as a resin or a surfactant, or in the form of a self-dispersing pigment.

[0023] <Self-dispersing pigment> A self-dispersing pigment is a pigment that can be dispersed and / or dissolved in an aqueous medium without a dispersant such as a resin or a surfactant. Here, "dispersed and / or dissolved in an aqueous medium without a dispersant" refers to a state in which the pigment is stably present in the aqueous medium due to the hydrophilic groups on its surface, even without using a dispersant to disperse the pigment.

[0024] Ink compositions containing self-dispersing pigments do not require the inclusion of a dispersant for dispersing the pigment, and there is almost no foaming due to the decrease in defoaming properties caused by the dispersant, making it easy to prepare ink compositions with excellent ejection stability. In addition, the generation of foreign matter due to drying at the gas-liquid interface caused by the dispersant is suppressed, resulting in excellent ejection reliability. In addition, since a significant increase in viscosity caused by the dispersant is suppressed, it is possible to contain a larger amount of pigment, making it possible to sufficiently increase the print density.

[0025] Examples of hydrophilic groups present on the surface of self-dispersing pigments include -OM, -COOM, -CO-, -SO3M, -SO2M, -SO2NH2, -RSO2M, -PO3HM, -PO3M2, -SON2NHCOR, -NH3, and -NR3. M in the formula is a hydrogen atom. , an alkali metal, ammonium, or organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms or a naphthyl group which may have a substituent.

[0026] When carbon black is used as a self-dispersing pigment, it is produced, for example, by subjecting the carbon black to a physical or chemical treatment to bond (graft) hydrophilic groups to the surface of the carbon black. Examples of such physical treatments include vacuum plasma treatment. Examples of chemical treatments include oxidation treatment with hypohalous acid and / or hypohalite, oxidation treatment with ozone, or oxidation treatment with persulfuric acid and / or persulfate.

[0027] In addition, as the carbon black used as the self-dispersing pigment, commercially available products can also be used, such as CAB-O-JET (registered trademark) 300 (manufactured by Cabot Specialty Chemicals, Inc.).

[0028] On the other hand, self-dispersing pigments of color pigments other than carbon black are produced by binding hydrophilic groups to the pigment surface via phenyl groups. As a surface treatment method for binding the above-mentioned functional group or its salt, which is a hydrophilic group, to the pigment surface via phenyl groups, various known surface treatment methods can be applied, such as a method in which a hydrophilic group is bound to the pigment surface via phenyl groups by binding sulfanilic acid, p-aminobenzoic acid, 4-aminosalicylic acid, etc. to the pigment surface. In addition, color pigments other than carbon black include pigments such as Pigment Yellow, Pigment Red, Pigment Violet, and Pigment Blue listed in the Color Index, as well as phthalocyanine, azo, anthraquinone, azomethine, and condensed ring pigments. In addition, organic pigments such as Yellow No. 4, No. 5, No. 205, and No. 401; Orange No. 228 and No. 405; and Blue No. 1 and No. 404, and inorganic pigments such as titanium oxide, zinc oxide, zirconium oxide, iron oxide, ultramarine, Prussian blue, and chrome oxide.

[0029] As such self-dispersing color pigments, commercially available products can be used, such as CAB-O-JET (registered trademark) 250C, CAB-O-JET (registered trademark) 260M, and CAB-O-JET (registered trademark) 470Y (all manufactured by Cabot Specialty Chemicals, Inc.).

[0030] The content of the pigment (solid content) is preferably 3% by mass or more, more preferably 4% by mass or more, based on the total amount (100 mass) of the ink composition. The content of the pigment (solid content) is preferably 8% by mass or less, more preferably 7% by mass or less, and particularly preferably 6% by mass or less, based on the total amount (100 mass) of the ink composition. When the content of the pigment (solid content) is within the above range, clogging recovery may be more excellent.

[0031] In addition, in the water-based inkjet ink composition according to this embodiment, the content by mass of the resin particles described below is less than the content by mass of the pigment. By satisfying this quantitative ratio relationship between the resin particles and the pigment, the water-based inkjet ink composition according to this embodiment can achieve both good fixation and good clogging recovery properties.

[0032] 1.2.Water The aqueous ink-jet ink composition according to this embodiment contains water. Moreover, the term "aqueous" composition refers to a composition in which water is one of the main solvents. Examples of water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, and water with reduced ionic impurities such as ultrapure water. Furthermore, if water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide is used, the growth of bacteria and fungi can be suppressed when the aqueous ink-jet ink composition is stored for a long period of time.

[0033] The water content is 30% by mass or more, preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, based on the total amount (100% by mass) of the ink composition. The upper limit of the water content is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less, based on the total amount (100% by mass) of the ink composition.

[0034] 1.3.Resin particles The water-based inkjet ink composition according to this embodiment contains resin particles.

[0035] Examples of the resin particles include resin particles made of urethane-based resins, acrylic-based resins (including styrene-acrylic-based resins), fluorene-based resins, polyolefin-based resins, rosin-modified resins, terpene-based resins, polyester-based resins, polyamide-based resins, epoxy-based resins, vinyl chloride-based resins, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate-based resins, etc. Among these, urethane-based resins, acrylic-based resins, polyolefin-based resins, and polyester-based resins are preferred. These resin particles are often handled in the form of an emulsion, but may also be in the form of a powder. The resin particles may be used alone or in combination of two or more types.

[0036] The urethane resin is a general term for resins having a urethane bond. In addition to the urethane bond, the urethane resin may be a polyether urethane resin having an ether bond in the main chain, a polyester urethane resin having an ester bond in the main chain, or a polycarbonate urethane resin having a carbonate bond in the main chain. In addition, as the urethane-based resin, commercially available products may be used, such as Superflex 420, 460, 460s, 840, E-4000 (trade names, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, D-6455 (trade names, manufactured by Dainichi Seiyaku Chemicals Mfg. Co., Ltd.), Takelac WS-5100, WS-6021, 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.).

[0037] Acrylic resin is a general term for polymers obtained by polymerizing at least an acrylic monomer such as (meth)acrylic acid or (meth)acrylic acid ester as one component, and examples thereof include resins obtained from acrylic monomers and copolymers of acrylic monomers and other monomers. Examples thereof include acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers. Examples of vinyl monomers include styrene.

[0038] In this specification, the acrylic resin may be a styrene-acrylic resin, which will be described later. In addition, in this specification, the term "(meth)acrylic" means at least one of acrylic and methacrylic.

[0039] Styrene-acrylic resins are copolymers obtained from styrene monomers and (meth)acrylic monomers, and examples of such copolymers include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers. 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, and PDX-714. No. 5, 538J, 7640, 7641, 631, 790, 780, 7610 (trade names, manufactured by BASF), Mowinyl 966A, 975N (trade names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Vinybran 2586 (manufactured by Nissin Chemical Industry Co., Ltd.), and the like may also be used.

[0040] The polyolefin resin has an olefin such as ethylene, propylene, butylene, etc. in the structural skeleton, and known resins can be appropriately selected and used. As the olefin resin, commercially available products can be used, for example, Arrowbase CB-1200, CD-1200 (product name, manufactured by Unitika Ltd.), etc. may be used.

[0041] 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 of Nippon Paint Co., Ltd., styrene-acrylic resin emulsions), Boncoat 4001 (trade name of DIC Corporation, acrylic resin emulsion), Boncoat 5454 (trade name of DIC Corporation, styrene-acrylic resin emulsion), Polysol AM-710, AM-920, AM-2300, AP-4735, AT-860, PSASE-4210E ( ... 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) (product name, manufactured by Showa Denko K.K.), Polysol SAE1014 (product name, styrene-acrylic resin emulsion, manufactured by Zeon Co., Ltd.), Saibinol SK-200 (product name, acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.) , AE-120A (JSR Corporation product name, acrylic resin emulsion), AE373D (E-Tech Corporation product name, carboxy-modified styrene-acrylic resin emulsion), Seikadine 1900W (Dainichiseika Chemical Industry Co., Ltd. product name, ethylene-vinyl acetate resin emulsion), Vinyblan 2682 (acrylic resin emulsion), Vinyblan 2886 (vinyl acetate-acrylic resin emulsion), Vinyblan 5202 (acetic acid acrylic resin emulsion) (Nissin Chemical Industry Co., Ltd. product name), Elitel KA-5071S, KT-8803, KT-9204, KT-870 1, KT-8904, KT-0507 (product name of Unitika Ltd., polyester resin emulsion), Hi-Tech SN-2002 (product name of Toho Chemical Co., Ltd., polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (product name of Mitsui Chemicals Polyurethanes, urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 700 (product name of Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), Parmarin UA-150 (manufactured by Sanyo Chemical Industries, Ltd.,Urethane resin emulsion), Sancure 2710 (manufactured by Lubrizol Japan, urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (manufactured by Kusumoto Chemicals Co., Ltd., urethane resin emulsion), Adeka Bontiter HUX-380, 290K (manufactured by ADEKA Corporation, urethane resin emulsion), Mowinyl 966A, Mowinyl 7320 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 35 2D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (all manufactured by BASF), NK Binder R-5HN (manufactured by Shin-Nakamura Chemical Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane: manufactured by DIC Corporation), Joncryl 7610 (manufactured by BASF), X-436 (manufactured by Seiko Polymer Co., Ltd., styrene-acrylic emulsion), etc.

[0042] The content of the resin particles is preferably 0.5 to 5.0% by mass, more preferably 0.5 to 4.7% by mass, even more preferably 0.5 to 4.5% by mass, and particularly preferably 0.5 to 4.2% by mass, relative to the total amount (100% by mass) of the ink composition. When the content of the resin particles is within the above range, the toner tends to have excellent fixing properties and excellent clogging recovery properties.

[0043] As described above, the water-based inkjet ink composition according to this embodiment has a resin particle content that is less than the pigment content by mass. By satisfying this quantitative ratio relationship between the resin particles and the pigment, the water-based inkjet ink composition according to this embodiment can achieve both good fixability and good clogging recovery properties.

[0044] 1.4.HEP The water-based inkjet ink composition according to this embodiment contains 1-(2-hydroxyethyl)-2-pyrrolidone (HEP). Conventionally, 2-pyrrolidone has often been used as a solvent for ink compositions, rather than 1-(2-hydroxyethyl)-2-pyrrolidone. However, it has been found that by including 1-(2-hydroxyethyl)-2-pyrrolidone, excellent fixability can be obtained even with a small amount of resin particles.

[0045] The content of 1-(2-hydroxyethyl)-2-pyrrolidone is preferably 0.1 to 5.0 mass% relative to the total amount (100 mass%) of the ink composition, more preferably 0.3 to 4.0 mass%, even more preferably 0.5 to 3.0 mass%, and particularly preferably 1.0 to 2.0 mass%. When the content of 1-(2-hydroxyethyl)-2-pyrrolidone is within the above range, the fixing property and clogging recovery property may be superior.

[0046] 1.5. Trimethylglycine The aqueous inkjet ink composition according to this embodiment contains trimethylglycine, which is a compound that has a positive charge and a negative charge in the same molecule and has no charge as a whole, and has a structure in which a quaternary ammonium group and a carboxyl group are bonded via a methylene group.

[0047] Trimethylglycine is a solid at room temperature and has low volatility, and therefore has high moisturizing properties. Therefore, it is highly effective as a moisturizing agent, and when it is blended in an ink composition, it can be expected to have the effect of suppressing evaporation of water from the ink composition. This is presumably what contributes to the excellent effect of clogging recovery achieved by the aqueous inkjet ink composition according to this embodiment.

[0048] The content of trimethylglycine is preferably 0.1 to 5.0% by mass, more preferably 0.3 to 4.0% by mass, even more preferably 0.5 to 3.0% by mass, and particularly preferably 1.0 to 2.0% by mass, relative to the total amount (100% by mass) of the ink composition. When the content of trimethylglycine is within the above range, the clogging recovery property may be more excellent.

[0049] Solvents From the viewpoint of further improving the fixability and further enjoying the effects of the present invention, the aqueous ink-jet ink composition according to this embodiment preferably contains a glycol ether penetrant as a solvent. That is, when a penetrant is contained, the ink tends to have excellent fixability due to improved drying properties, but the ink may have unstable dispersibility of the ink components, which may lead to poor clogging recovery. However, according to the aqueous ink-jet ink composition according to this embodiment, even when such a penetrant is contained, it is possible to maintain good clogging recovery and, in addition, obtain better fixability.

[0050] 1.6.1. Glycol ethers The aqueous inkjet ink composition according to this embodiment preferably contains a glycol ether. The glycol ether is not particularly limited, but examples thereof include glycol diethers and glycol monoethers.

[0051] Examples of glycol diethers include dialkyl ethers of glycols selected from ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol, etc. More specific examples include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl 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, and dipropylene glycol diethyl ether.

[0052] Examples of glycol monoethers include monoalkyl ethers of glycols selected from ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol, etc. More specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl 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, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether.

[0053] Among these glycol ethers, the aqueous ink-jet ink composition preferably contains a compound represented by the following formula (1) as the glycol ether. When such a compound is contained, the fixability tends to be further improved. R 1 O-(R 2 O) n -H (1) (R 1 : an alkyl group having 1 to 8 carbon atoms, R 2 : an alkylene group having 2 to 4 carbon atoms, n: an integer of 1 to 10)

[0054] Examples of glycol ethers represented by formula (1) include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether (TEGmME), triethylene glycol monoethyl ether (TEGmEE), triethylene glycol monobutyl ether (TEGmBE), tetraethylene glycol monomethyl ether, propylene glycol monomethyl ether, etc. The glycol ether represented by formula (1) is preferably any one of triethylene glycol monomethyl ether (TEGmME), triethylene glycol monoethyl ether (TEGmEE), and triethylene glycol monobutyl ether (TEGmBE), and more preferably triethylene glycol monomethyl ether (TEGmME). or triethylene glycol monoethyl ether (TEGmEE), more preferably triethylene glycol monomethyl ether (TEGmME). When the glycol ether contains the above compound, the fixing property tends to be more excellent.

[0055] The glycol ether may contain one or more kinds.

[0056] The content of glycol ether is preferably 0.5 to 5.0% by mass, more preferably 1.0 to 4.0% by mass, even more preferably 1.5 to 3.5% by mass, and particularly preferably 2.0 to 3.0% by mass, relative to the total amount (100% by mass) of the ink composition. When the content of glycol ether is within the above range, the fixability tends to be more excellent.

[0057] 1.6.2. Other Solvents The aqueous inkjet ink composition according to this embodiment may contain a solvent other than glycol ether. Examples of such a solvent include 1,2-alkanediols, polyhydric alcohols, and cyclic amides. These can be used alone or in combination of two or more.

[0058] Examples of 1,2-alkanediols include 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol. 1,2-alkanediols are excellent in increasing the wettability of the ink to the recording medium and uniformly wetting the recording medium. Therefore, fixability may be further improved. When 1,2-alkanediols are added, the content is preferably 1% by mass or more and 5% by mass or less with respect to the total amount of the ink composition.

[0059] Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,3-pentanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, and glycerin. By adding polyhydric alcohols to the ink, it is possible to suppress the ink from drying and solidifying in the ejection nozzle of the inkjet head, thereby reducing clogging of the ejection nozzle and ejection failure. When polyhydric alcohols are added, the content is preferably 2% by mass or more and 20% by mass or less with respect to the total amount of the ink composition. Polyhydric alcohols that are solid at 20° C. have the same effect as the polyhydric alcohols in the solvent and may be used in the same manner. Examples of polyhydric alcohols that are solid at 20° C. include trimethylolpropane.

[0060] Examples of cyclic amides include compounds having a ring structure containing an amide group. Examples of such compounds include γ-lactams such as 2-pyrrolidone, 1-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone), 1-ethyl-2-pyrrolidone (N-ethyl-2-pyrrolidone), 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, and N-vinyl-2-pyrrolidone (NVP), β-lactams, δ-lactams, and ε-lactams such as ε-caprolactam.

[0061] 1.7. pH Adjusters The aqueous inkjet ink composition according to this embodiment has improved dispersion stability of the ink composition. For this purpose, it is preferable to contain a pH adjuster. Examples of the pH adjuster include an appropriate combination of an acid, a base, a weak acid, and a weak base. Examples of the acid and base used in such a combination include an inorganic acid, an inorganic base, an organic acid, and an organic base.

[0062] Examples of the inorganic acid include sulfuric acid, hydrochloric acid, and nitric acid.

[0063] Examples of the inorganic base include lithium hydroxide, sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate, disodium hydrogen phosphate, potassium carbonate, sodium carbonate, sodium hydrogen carbonate, ammonia, and the like.

[0064] As the organic acid, adipic acid, citric acid, succinic acid, lactic acid, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), morpholinoethanesulfonic acid (MES), carbamoylmethyliminobisacetic acid (ADA), piperazine-1,4-bis(2-ethanesulfonic acid) (PIPES), N-(2-acetamido)-2-aminoethanesulfonic acid (ACES), cholamine hydrochloride, N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), acetamidoglycine, tricine, glycineamide, Good's buffer such as bicine, phosphate buffer, citrate buffer, Tris buffer, etc. may be used.

[0065] The organic base may be an organic amine, etc. Examples of the organic amine include triethanolamine (TEA), diethanolamine, monoethanolamine, tripropanolamine, triisopropanolamine, diisopropanolamine, and trishydroxymethylaminomethane.

[0066] Among these, it is more preferable to use an organic amine. When an inorganic base such as potassium hydroxide is used, as the ink composition dries and becomes concentrated, the pigment, resin, etc. may aggregate. In particular, aggregation is likely to occur significantly in a small space such as the nozzle of an inkjet head. In contrast, when an organic amine is used, such aggregation of the ink composition is reduced, and clogging recovery tends to be more excellent.

[0067] 1.8.Other Ingredients The water-based inkjet ink composition according to this embodiment may contain a surfactant and the like.

[0068] <Surfactant> The aqueous ink-jet ink composition according to this embodiment may contain a surfactant. The surfactant can be used to reduce the surface tension of the aqueous ink-jet ink composition and adjust and improve the wettability with a recording medium, for example, the permeability into fabrics and the like. As the surfactant, any of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants can be used, and these may be used in combination. Among the surfactants, acetylene glycol surfactants, silicone surfactants, and fluorine-based surfactants can be preferably used.

[0069] The acetylene glycol surfactant is not particularly limited, but examples thereof include Surfynol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, DF110D (product name, manufactured by Air Products and Chemicals Inc.), Olfine B, Y, P, A, STG, SPC, E1004, E1010, Examples of such polyether ethers include PD-001, PD-002W, PD-003, PD-004, PD-005, EXP.4001, EXP.4036, EXP.4051, EXP.4123, EXP.4300, AF-103, AF-104, AK-02, SK-14, and AE-3 (trade names, manufactured by Nissin Chemical Industry Co., Ltd.), and Acetylenol E00, E00P, E40, and E100 (trade names, manufactured by Kawaken Fine Chemical Co., Ltd.).

[0070] The silicone surfactant is not particularly limited, but a polysiloxane compound is preferred. The polysiloxane compound is not particularly limited, but for example, a polyether-modified organosiloxane is exemplified. Examples of commercially available polyether-modified organosiloxanes include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (trade names, manufactured by BYK Co.), 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, KF-6015, and KF-6017 (trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0071] As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and a specific example thereof is BYK-340 (product name, manufactured by BYK-Chemie Japan KK).

[0072] When a surfactant is added to the aqueous ink-jet ink composition, the surfactant is preferably added in an amount of 0.01% by mass to 3% by mass, more preferably 0.05% by mass to 2% by mass, even more preferably 0.1% by mass to 1.5% by mass, and particularly preferably 0.2% by mass to 1% by mass, based on the total amount of the aqueous ink-jet ink composition. If the surfactant content is within the above range, clogging recovery properties may be improved.

[0073] <Other> The water-based inkjet ink composition according to this embodiment may contain, as other components, additives that can be typically used in water-based inkjet ink compositions for inkjet printing, such as chelating agents, ureas, preservatives / antifungals, rust inhibitors, sugars, antioxidants, ultraviolet absorbers, and oxygen absorbers.

[0074] 1.9.Physical properties etc. The water-based inkjet ink composition according to this embodiment can be obtained by mixing the above-mentioned components in any order, and removing impurities by filtering or the like as necessary. As a mixing method, a method in which materials are added sequentially to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirred and mixed is preferably used. As a filtering method, for example, centrifugal filtering or filter filtering can be performed as necessary.

[0075] From the viewpoint of reliability as an inkjet ink, the aqueous inkjet ink composition preferably has a surface tension at 20° C. of 20 mN / m or more and 40 mN / m or less, and more preferably 22 mN / m or more and 35 mN / m or less. From the same viewpoint, the viscosity of the ink at 20° C. is preferably 1.5 mPa·s or more and 10 mPa·s or less, and more preferably 2 mPa·s or more and 8 mPa·s or less. One method for keeping the surface tension and viscosity within the above ranges is to adjust the types of the above-mentioned solvent and surfactant, and the amounts of these and water added.

[0076] 1.10.Applications The aqueous inkjet ink composition according to this embodiment can be suitably used in an inkjet recording device equipped with a line head. Line heads have a relatively large number of nozzles, so they are prone to clogging and require higher clogging recovery properties. Even when the aqueous inkjet ink composition according to the embodiment is used in an inkjet recording device equipped with such a line head, it is possible to ensure good clogging recovery properties and achieve both good fixation properties and good clogging recovery properties.

[0077] An example of an inkjet recording apparatus equipped with a line head that can be used with the aqueous inkjet ink composition according to this embodiment will be described below with reference to the drawings. Figure 1 is an explanatory diagram that shows a schematic configuration of an inkjet recording apparatus equipped with a line head.

[0078] As shown in FIG. 1, inkjet recording device 200 includes a transport roller 113 that transports recording medium 111 onto a platen 112, a step motor 114 that rotates and drives the transport roller 113, a line head 120 that is attached by a guide rail 115 so as to be movable in a direction perpendicular to the transport direction of the recording medium 111 (the direction of the arrow in FIG. 1) and ejects ink droplets onto the transported recording medium 111, a vibration element (not shown) that vibrates the line head 120 in a direction perpendicular to the transport direction of the recording medium 111, an ink cartridge 135, and a controller 140 that controls the entire device.

[0079] The vibration element is formed of, for example, a piezoelectric element (electrostrictive vibrator) such as PZT, and is attached to the line head 120. Therefore, by vibrating the vibration element, it is possible to vibrate the line head 120 along the guide rail 115 in a direction perpendicular to the conveying direction of the recording medium 111. However, it is not essential to vibrate in this perpendicular direction.

[0080] Controller 140 is configured as a microprocessor centered around CPU 141, and in addition to CPU 141, includes ROM 142 for storing various processing programs, RAM 143 for temporarily storing data, flash memory 144 to which data can be written and erased, interface (I / F) 145 for exchanging information with external devices, and input / output ports (not shown).

[0081] A print buffer area is provided in the RAM 143, and this print buffer area is capable of storing print data received from a user PC 146 via an interface (I / F) 145. Various operation signals and the like from an operation panel 147 are input to the controller 140 via an input port, and drive signals to the line head 120, drive signals to the step motor 114, output signals to the operation panel 147, and the like are output from the controller 140 via an output port.

[0082] The operation panel 147 is a device for inputting various instructions from the user and displaying and outputting the status. Although not shown, the operation panel 147 is provided with a display for displaying characters, figures, or symbols corresponding to the various instructions, as well as buttons for the user to perform various operations.

[0083] FIG. 2 is a plan view showing a schematic structure of the line head. As shown in FIG. 2, the line head 120 includes nozzle rows 121a, 121b, 121c, and 121d in which a plurality of nozzles are arranged in a direction perpendicular to the transport direction, and has a recording area larger than the width of the transported recording medium 111, so that one line of an image can be recorded at once on the transported recording medium 111. In addition, after one scan in which the recording medium is transported, the recording medium can be returned in the opposite direction to the transport direction and transported again to perform another scan, thereby performing recording by performing two or more scans. In this case, it is also possible to change the position of the line head in the direction perpendicular to the transport direction between scans and perform the second and subsequent scans at different positions, thereby increasing the recording resolution in the perpendicular direction. In this case, the above-mentioned vibration of the line head is not particularly performed. It is also possible to increase the amount of ink composition deposited on the recording medium by scanning two or more times, regardless of whether the line head is vibrated or not, and whether the position of the line head in the perpendicular direction is changed. Furthermore, the scanning may be performed while changing the relative positions of the line head and the recording medium, and may be performed while the line head moves relative to the recording medium fixed to the platen area. Examples of such a recording method include those described in JP-A-2009-90635. Incidentally, the relative positions of the line head and the recording medium are changed by conveying the recording medium or by moving the carriage carrying the head.

[0084] In addition, in the example of Figure 1, the ink ejection method of the line head 120 employs a method in which droplets of the ink composition are ejected by utilizing the pressure generated in the ink pressure chamber of the line head using a vibration element (not shown). However, this is not limited to this, and various methods can be applied, such as a thermal inkjet method in which bubbles are generated by a heating element and the ink composition is ejected by applying pressure.

[0085] In the inkjet recording device 200, for example, the nozzle rows 121a, 121b, 121c, and 121d are used in sequence to eject and deposit each ink composition onto a recording medium. The line head 120 is not limited to this configuration, and may be configured by arranging a plurality of line-type heads each having one nozzle row in parallel. In this case, the line-type heads may be configured to have a space between them. In addition, in FIG. 2, the nozzle rows of the line head 120 are arranged in a direction perpendicular to the transport direction, but they may be arranged in a direction intersecting the transport direction.

[0086] 2. 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. In the following, "%" is based on mass unless otherwise specified.

[0087] 2.1. Preparation of Water-Based Inkjet Ink Composition The components were placed in a container so as to obtain the composition shown in Table 1 below, and 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 water-based inkjet ink compositions according to Examples and Comparative Examples. The numerical values ​​in the table for the pigment, resin particles, and surfactant represent the amounts converted to their solid contents.

[0088] [Table 1]

[0089] The following provides additional explanations for each component shown in Table 1 above. <Pigments> Black pigment: (Product name "CAB-O-JET (registered trademark) 300", manufactured by Cabot Specialty Chemicals, Inc., self-dispersed carbon black dispersion) Cyan pigment: (Product name "CAB-O-JET (registered trademark) 250C", manufactured by Cabot Specialty Chemicals, Inc., self-dispersed cyan pigment dispersion) · Magenta pigment: (Product name "CAB-O-JET® 260M", manufactured by Cabot Specialty Chemicals Ink Co., Ltd., self-dispersing magenta pigment dispersion liquid) · Yellow pigment: (Product name "CAB-O-JET® 470Y", manufactured by Cabot Specialty Chemicals Ink Co., Ltd., self-dispersing yellow pigment dispersion liquid) <Resin particles> · Superflex 420: (Product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion) · X-436: (Product name, manufactured by Seiko Polymer Co., Ltd., styrene-acrylic emulsion) <Solvent> · HEP: 1-(2-Hydroxyethyl)-2-pyrrolidone <Solvent (penetrant)> · TEGmBE: Triethylene glycol monobutyl ether · TEGmME: Triethylene glycol monomethyl ether · TEGmEE: Triethylene glycol monoethyl ether <Surfactant> · Orfin E1010: (Product name, manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol-based surfactant) <pH adjuster> · TEA: Triethanolamine

[0090] 2.2. Evaluation method 2.2.1. Evaluation of fixability (resistance to line marker) Each aqueous inkjet ink composition obtained above was filled into an ink cartridge of a printer "PX-M860F" manufactured by Seiko Epson Corporation, and a character pattern was printed on a recording medium in an environment of a temperature of 25°C and a relative humidity of 50%. As the recording medium, A4 size (210 mm × 297 mm) copy paper "Xerox P paper" (manufactured by Fuji Xerox Co., Ltd., basis weight 64 g / m 2 , paper thickness 88 μm) was used. Immediately after printing, the character portion was rubbed with a line marker "OPTEX CARE" (Zebra Co., Ltd.), and the bleeding condition of the ink was judged according to the following criteria. B or above was regarded as a good level. <Judgment criteria> A: No bleeding in rubbed area B: There is bleeding in the rubbed area, but it is not noticeable. C: There is bleeding in the rubbed area, which is somewhat noticeable. D: There is bleeding in the rubbed area, which is quite noticeable

[0091] 2.2.2. Evaluation of clogging recovery Each of the water-based inkjet ink compositions obtained above was filled into an ink cartridge of a printer "PX-M860F" manufactured by Seiko Epson Corporation, and printing was performed. Then, the printer was turned off during printing, and the recording head was removed from the cap. The printer was then left for an arbitrary number of days in a 40°C environment. Specifically, the printer was left for 3 days in a 40°C environment (40°C*3d), 7 days in a 40°C environment (40°C*7d), or 14 days in a 40°C environment (40°C*14d). After being left for an arbitrary number of days, cleaning was repeatedly performed on each of the printers that had been left for the arbitrary number of days until all of the nozzles had recovered, and the following criteria were used to determine whether the printer had recovered or not. A grade of B or higher was considered to be good. Furthermore, when a similar evaluation was carried out using a Seiko Epson Corporation printer "LX-10050MF" equipped with a line head, the aqueous inkjet ink compositions of Examples 1 to 17 were rated as B or higher. <Judgment criteria> A: Recovery in less than 3 cleanings B: Recovery after 3 to 6 cleanings C: Recovered after 6 to 9 cleanings D: No recovery even after 9 or more cleanings

[0092] 2.3.Evaluation Results The evaluation results are shown in Table 1 above.

[0093] The aqueous inkjet ink compositions of the examples, which contain a pigment, water, resin particles, 1-(2-hydroxyethyl)-2-pyrrolidone (HEP), and trimethylglycine, and in which the content of the resin particles by mass is less than the content of the pigment by mass, were able to achieve both good fixation properties and good clogging recovery properties.

[0094] In contrast, in each of the comparative examples, it was not possible to achieve both good fixing properties and good clogging recovery properties because the specific components were not all contained, or the quantitative ratio relationship of the specific components was not satisfied, or both.

[0095] The following can be derived from the above-described embodiment.

[0096] One embodiment of the aqueous inkjet ink composition comprises: Pigment, water, Resin particles; 1-(2-hydroxyethyl)-2-pyrrolidone, trimethylglycine, The content by mass of the resin particles is less than the content by mass of the pigment.

[0097] In the above embodiment of the aqueous ink-jet ink composition, The content of the resin particles may be 0.5 to 5.0% by mass with respect to the total amount of the ink composition.

[0098] In the above embodiment of the aqueous ink-jet ink composition, The solvent may contain a glycol ether.

[0099] In the above embodiment of the aqueous ink-jet ink composition, The content of the glycol ether may be 0.5 to 5.0% by mass with respect to the total amount of the ink composition.

[0100] In the above embodiment of the aqueous ink-jet ink composition, The glycol ether may contain a compound represented by the following formula (1). R 1 O-(R 2 O) n -H (1) (R 1 : an alkyl group having 1 to 8 carbon atoms, R 2 : an alkylene group having 2 to 4 carbon atoms, n: an integer of 1 to 10)

[0101] In the above embodiment of the aqueous ink-jet ink composition, It may further contain an organic amine.

[0102] In the above embodiment of the aqueous ink-jet ink composition, The ink jet recording apparatus may be used in an ink jet recording device equipped with a line head.

[0103] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the present invention includes a configuration that is substantially the same as the configuration described in the embodiment, for example, a configuration that has the same function, method, and result, or a configuration that has the same purpose and effect. The present invention also includes a configuration in which non-essential parts of the configuration described in the embodiment are replaced. The present invention also includes a configuration that has the same action and effect as the configuration described in the embodiment, or a configuration that can achieve the same purpose. The present invention also includes a configuration in which publicly known technology is added to the configuration described in the embodiment. [Explanation of symbols]

[0104] 111...recording medium, 112...platen, 113...transport roller, 114...step motor, 115...guide rail, 120...line head, 121a, 121b, 121c, 121d...nozzle array, 135...ink cartridge, 140...controller, 141...CPU, 142...ROM, 143...RAM, 144...flash memory, 145...interface, 146...user PC, 147...operation panel, 200...inkjet recording device

Claims

1. Pigment, water, Resin particles; 1-(2-hydroxyethyl)-2-pyrrolidone, trimethylglycine, the content by mass of the resin particles is less than the content by mass of the pigment.

2. 2. The water-based ink-jet ink composition according to claim 1, wherein the content of the resin particles is 0.5 to 5.0% by mass based on the total amount of the ink composition.

3. The water-based ink-jet ink composition according to claim 1 or 2, which contains a glycol ether as a solvent.

4. 4. The water-based ink-jet ink composition according to claim 3, wherein the content of the glycol ether is 0.5 to 5.0% by mass based on the total amount of the ink composition.

5. The aqueous ink-jet ink composition according to claim 3 or 4, comprising a compound represented by the following formula (1) as the glycol ether: R １ O-(R ２ O) ｎ -H ・・・(1) (R １ : an alkyl group having 1 to 8 carbon atoms, R ２ : an alkylene group having 2 to 4 carbon atoms, n: an integer from 1 to 10)

6. The water-based ink-jet ink composition according to claim 1 , further comprising an organic amine.

7. The water-based ink-jet ink composition according to claim 1 , which is used in an ink-jet recording apparatus equipped with a line head.

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