Aqueous ink for inkjet recording, inkjet recording device, and inkjet recording method

Abstract

To provide an aqueous ink for inkjet recording which replaces part of petroleum-derived materials with plant-derived materials, while retaining the same level of performance as traditional aqueous inks for inkjet recording.SOLUTION: An aqueous ink for inkjet recording of the present invention comprises water, a colorant, and a polysaccharide, wherein the polysaccharide includes at least one selected from xylan and derivatives thereof, and the viscosity of the aqueous ink is less than 10 mPa s at 25°C.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-based ink for ink-jet recording, an ink-jet recording apparatus, and an ink-jet recording method. [Background technology]

[0002] An example of a water-based ink for inkjet recording is described in Patent Document 1. Patent Document 1 discloses a water-based ink for inkjet recording that contains a colorant, resin particles for imparting fixability to a recording medium, and the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-090266 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, with the growing awareness of environmental issues, there has been a demand for reducing the environmental impact of water-based inks for inkjet recording. On the other hand, as disclosed in Patent Document 1, petroleum-derived polymers are generally used to impart properties such as fixability to water-based inks for inkjet recording. From the viewpoint of reducing the environmental impact, it is necessary to refrain from using petroleum-derived raw materials as much as possible.

[0005] Therefore, an object of the present invention is to provide an aqueous ink for inkjet recording, an inkjet recording apparatus, and an inkjet recording method in which a part of the petroleum-derived raw materials is replaced with plant-derived raw materials while maintaining the same performance as conventional aqueous inks for inkjet recording. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the aqueous ink for inkjet recording of the present invention comprises water, a colorant, and a polysaccharide, the polysaccharide comprising at least one of xylan and a derivative thereof, and the viscosity of the aqueous ink at 25°C is less than 10 mPa·s.

[0007] The ink-jet recording apparatus of the present invention includes an ink flow path and an ink ejection means, and ejects the water-based ink for ink-jet recording of the present invention, which is supplied to the ink flow path, onto a recording medium by the ink ejection means.

[0008] The inkjet recording method of the present invention includes a recording step, which includes a step of applying a water-based ink to a recording medium by an inkjet method to perform recording, and the water-based ink is the water-based ink for inkjet recording of the present invention. Effect of the Invention

[0009] According to the present invention, it is possible to provide an aqueous ink for inkjet recording in which a part of the petroleum-derived raw materials is replaced with plant-derived raw materials while maintaining the same performance as conventional aqueous inks for inkjet recording. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view showing the configuration of an example of an inkjet recording apparatus of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the present invention, "mass" may be read as "weight" unless otherwise specified. For example, "mass ratio" may be read as "weight ratio" unless otherwise specified, and "mass%" may be read as "weight%" unless otherwise specified.

[0012] Furthermore, when a mechanism is mentioned in the following embodiments and examples, the mechanism is merely presumed, and is not limited to the mechanism described.

[0013] <Water-based ink for inkjet recording> The water-based ink for ink-jet recording of the present invention (hereinafter, may be referred to as "water-based ink" or "ink") will be described. The water-based ink of the present invention contains water, a colorant, and a polysaccharide.

[0014] The polysaccharide includes at least one of xylan and a derivative thereof. The polysaccharide may include, for example, xylan. The polysaccharide may be xylan. When the polysaccharide is xylan, it is preferable in that fixability and IJ ejectability described later can be achieved at the same time. That is, by using xylan as the polysaccharide, it is possible to maintain the optimum ink viscosity for ejection by an inkjet head while imparting fixability to a recording medium to the aqueous ink. Note that xylan has a xylose skeleton in its structure, and examples of materials having a xylose skeleton include soybean hemicellulose. However, as a result of experiments conducted by the inventors, it has been found that the ink viscosity of soybean hemicellulose increases even when added in small amounts to an aqueous ink. That is, when a small amount of soybean hemicellulose is added as the polysaccharide in order to maintain the optimum ink viscosity for ejection by an inkjet head, it is not possible to impart fixability to a recording medium to the aqueous ink. Also, when a large amount of soybean hemicellulose is added as the polysaccharide in order to impart fixability to a recording medium, it is not possible to maintain the optimum ink viscosity for ejection by an inkjet head. Therefore, among substances having a xylose skeleton, xylan is superior in terms of fixability to a recording medium and optimum ink viscosity for ejection from an inkjet head.

[0015] The viscosity of the aqueous ink of the present invention at 25° C. is less than 10.0 mPa·s. The upper limit of the viscosity may be, for example, 9.0 mPa·s or less, 8.0 mPa·s or less, 7.0 mPa·s or less, or 6.0 mPa·s or less, and the lower limit is not particularly limited, and may be, for example, 1.0 mPa·s or more, 2.0 mPa·s or more, 3.0 mPa·s or more, 4.0 mPa·s or more, or 5.0 mPa·s or more.

[0016] The reason why the viscosity of the aqueous ink of the present invention at 25° C. is set to less than 10 mPa·s is, for example, as follows. From the viewpoint of reducing the environmental load, it is preferable to use an aqueous ink as the ink for inkjet recording. In addition, when ink is discharged from an inkjet head using an inkjet recording device, the lower the viscosity of the ink, the lower the ejection energy (for example, the voltage applied to eject the ink) during ink ejection can be. Therefore, it is more preferable to use an aqueous ink with a low viscosity from the viewpoint of reducing the environmental load. Here, the appropriate viscosity of an inkjet head capable of ejecting an aqueous ink is often set to less than 10 mPa·s. Although there are inkjet heads with an appropriate ink viscosity of 10 mPa·s or more, when an ink with a low viscosity is ejected using such an inkjet head, it may not be possible to generate droplets that fly stably in space after ejection. Therefore, as the aqueous ink, it is necessary to use an aqueous ink with a viscosity of less than 10 mPa·s at 25° C. from the viewpoint of the appropriate viscosity of the inkjet head in addition to the viewpoint of reducing the environmental load.

[0017] In the aqueous ink of the present invention, the solid content of the polysaccharide in the weight of the entire aqueous ink may be, for example, 1.0% by weight or more, 2.0% by weight or more, 3.0% by weight or more, or 4.0% by weight or more, and may be 20.0% by weight or less, 19.0% by weight or less, 18.0% by weight or less, 17.0% by weight or less, 15.0% by weight or less, or 14.0% by weight or less. When the colorant is a self-dispersion pigment described later, from the viewpoint of fixability and IJ jettability described later, the solid content of the polysaccharide in the weight of the entire aqueous ink is preferably 4.0 to 17.0% by weight. When the colorant is a resin dispersion pigment described later, from the viewpoint of fixability and IJ jettability described later, the solid content of the polysaccharide in the weight of the entire aqueous ink is preferably 4.0 to 14.0% by weight.

[0018] The polysaccharide may, for example, function as a fixing agent for imparting fixability of the water-based ink to the recording medium, or may have other functions.

[0019] The colorant may include, for example, a pigment, a dye, and the like.

[0020] The pigment is not particularly limited, and examples thereof include carbon black, inorganic pigments, and organic pigments. Examples of the carbon black include furnace black, lamp black, acetylene black, and channel black. Examples of the inorganic pigment include titanium oxide, iron oxide-based inorganic pigments, and carbon black-based inorganic pigments. Examples of the organic pigment include azo pigments such as azo lake, insoluble azo pigment, condensed azo pigment, and chelate azo pigment; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye lake pigments such as basic dye lake pigments and acid dye lake pigments; nitro pigments; nitroso pigments; aniline black daylight fluorescent pigments; and the like. Other pigments can also be used as long as they are dispersible in the aqueous phase. Specific examples of these pigments include, for example, CI Pigment Black 1, 6 and 7; CI Pigment Yellow 1, 2, 3, 12, 13, 14, 15, 16, 17, 55, 74, 78, 150, 151, 154, 180, 185 and 194; CI Pigment Orange 31 and 43; CI Pigment Red 2, 3, 5, 6, 7, 12, 15, 16, 48, 48:1, 53:1, 57, 57:1, 112, 122, 123, 1 39, 144, 146, 149, 150, 166, 168, 175, 176, 177, 178, 184, 185, 190, 202, 209, 221, 222, 224 and 238; CI Pigment Violet 19 and 196; CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 16, 22 and 60; CI Pigment Green 7 and 36; and solid solutions of these pigments.

[0021] The pigment may be dispersed in a solvent by a resin dispersant (also referred to as a resin-dispersed pigment). The resin dispersant may be, for example, a general polymer dispersant (also referred to as a pigment dispersion resin or a resin dispersant), or may be prepared in-house. In the aqueous ink of the present invention, the pigment may be encapsulated by a polymer. The resin dispersant may be, for example, one containing at least one of methacrylic acid and acrylic acid as a monomer, and may be, for example, a commercially available product. The resin dispersant may be, for example, a hydrophobic monomer such as styrene, a styrene derivative, vinyl naphthalene, a vinyl naphthalene derivative, or an aliphatic alcohol ester of an α,β-ethylenically unsaturated carboxylic acid, or a block copolymer, graft copolymer, or random copolymer consisting of two or more monomers selected from the group consisting of acrylic acid, an acrylic acid derivative, a maleic acid, a maleic acid derivative, an itaconic acid, an itaconic acid derivative, a fumaric acid, or a fumaric acid derivative, or a salt thereof. Examples of the commercially available products include "Joncryl (registered trademark) 611", "Joncryl (registered trademark) 60", "Joncryl (registered trademark) 586", "Joncryl (registered trademark) 687", "Joncryl (registered trademark) 63", and "Joncryl (registered trademark) HPD296" manufactured by Johnson Polymer Co., Ltd.; "Disperbyk190" and "Disperbyk191" manufactured by BYK-Chemie; and "Solsperse 20000" and "Solsperse 27000" manufactured by Zena Chemical.

[0022] The pigment may be dispersed using a dispersing resin by using a dispersing device, which is not particularly limited as long as it is a general dispersing device, and examples of the dispersing device include a ball mill, a roll mill, and a sand mill (e.g., a high-speed type).

[0023] The pigment may be a self-dispersing pigment. The self-dispersing pigment is, for example, a pigment particle having at least one hydrophilic functional group such as a carbonyl group, a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, or a salt thereof, which is introduced by chemical bonding directly or via another group, and is therefore dispersible in water without using a dispersant. The self-dispersing pigment may be, for example, a pigment treated by the method described in JP-A-8-3498, JP-T-2000-513396, JP-T-2008-524400, JP-T-2009-515007, JP-T-2011-515535, or the like. Both inorganic and organic pigments can be used as the raw material for the self-dispersing pigment. In addition, examples of pigments suitable for the treatment include carbon blacks such as "MA8" and "MA100" manufactured by Mitsubishi Chemical Corporation. The self-dispersing pigment may be, for example, a commercially available product. Examples of the commercially available products include "CAB-O-JET (registered trademark) 200", "CAB-O-JET (registered trademark) 250C", "CAB-O-JET (registered trademark) 260M", "CAB-O-JET (registered trademark) 270Y", "CAB-O-JET (registered trademark) 300", "CAB-O-JET (registered trademark) 400", "CAB-O-JET (registered trademark) 450C", "CAB-O-JET (registered trademark) 465M" and "CAB-O-JET (registered trademark) 470Y" manufactured by Cabot Corporation; "BONJET (registered trademark) BLACK CW-2" and "BONJET (registered trademark) BLACK CW-3" manufactured by Orient Chemical Industry Co., Ltd.; and "LIOJET (registered trademark) WD BLACK 002C" manufactured by Toyo Ink Mfg. Co., Ltd.

[0024] The pigment solid content (pigment solid content amount) in the total amount of the water-based ink is not particularly limited and can be appropriately determined depending on, for example, the desired optical density and saturation, etc. The pigment solid content amount is, for example, 0.1% by mass to 20.0% by mass, 1.0% by mass to 15.0% by mass, or 2.0% by mass to 10.0% by mass.

[0025] The pigments may be used alone or in combination of two or more kinds.

[0026] The dye is not particularly limited, and examples thereof include direct dyes, acid dyes, basic dyes, and reactive dyes. Specific examples of the dye include CI Direct Black, CI Direct Blue, CI Direct Red, CI Direct Yellow, CI Direct Orange, CI Direct Violet, CI Direct Brown, CI Direct Green, CI Acid Black, CI Acid Blue, CI Acid Red, CI Acid Yellow, CI Acid Orange, CI Acid Violet, CI Basic Black, CI Basic Blue, CI Basic Red, CI Basic Violet, and CI Food Black. Examples of the CI Direct Black include CI Direct Black 17, 19, 32, 51, 71, 108, 146, 154, and 168. Examples of the CI Direct Blue include CI Direct Blue 6, 22, 25, 71, 86, 90, 106, and 199. Examples of the CI Direct Red include CI Direct Red 1, 4, 17, 28, 83, and 227. Examples of the CI Direct Yellow include CI Direct Yellow 12, 24, 26, 86, 98, 132, 142, and 173. Examples of the CI Direct Orange include CI Direct Orange 34, 39, 44, 46, and 60. Examples of the CI Direct Violet include CI Direct Violet 47 and 48. Examples of the CI Direct Brown include CI Direct Brown 109. Examples of the CI Direct Green include CI Direct Green 59. Examples of the CI Acid Black include CI Acid Black 2, 7, 24, 26, 31, 52, 63, 112, and 118. Examples of the CI Acid Blue include CI Acid Blue 9, 22, 40, 59, 90, 93, 102, 104, 117, 120, 167, 229, and 234.Examples of the CI Acid Red include CI Acid Red 1, 6, 32, 37, 51, 52, 80, 85, 87, 92, 94, 115, 180, 256, 289, 315, and 317. Examples of the CI Acid Yellow include CI Acid Yellow 11, 17, 23, 25, 29, 42, 61, and 71. Examples of the CI Acid Orange include CI Acid Orange 7 and 19. Examples of the CI Acid Violet include CI Acid Violet 49. Examples of the CI Basic Black include CI Basic Black 2. Examples of the CI Basic Blue include CI Basic Blue 1, 3, 5, 7, 9, 24, 25, 26, 28, and 29. Examples of the CI Basic Red include CI Basic Red 1, 2, 9, 12, 13, 14, and 37. Examples of the CI Basic Violet include CI Basic Violet 7, 14, and 27. Examples of the CI Food Black include CI Food Black 1 and 2.

[0027] The solid content of the dye in the total amount of the water-based ink (dye solid content amount) is not particularly limited and can be appropriately determined depending on, for example, the desired optical density and saturation, etc. The dye solid content amount is, for example, 0.1% by weight to 20.0% by weight, and preferably 0.3% by weight to 10.0% by weight.

[0028] The dyes may be used alone or in combination of two or more kinds.

[0029] The water may be ion-exchanged water, pure water, or the like.

[0030] In the total weight of the aqueous ink, the content of the water is preferably greater than the content of each of the other components. For example, when the total weight of the aqueous ink is 40% by weight, and the other components are 10% by weight of component A, 20% by weight of component B, and 30% by weight of component C, the content of the water is greater than the content of each of the components A to C, and therefore the content of the water is greater than the content of each of the other components. Therefore, for example, the content of the water in the total weight of the aqueous ink is not particularly limited as long as it is greater than the content of each of the other components.

[0031] The content ratio (a / b) of the sum (a) of the solid content of the colorant and the solid content of the polysaccharide to the water content (b) may, for example, have an upper limit value less than 0.5, 0.4 or less, or 0.3 or less, and a lower limit value of 0.1 or more, or 0.2 or more.

[0032] The water-based ink may further contain a water-soluble solvent as a solvent other than water. The water-soluble solvent may be, for example, a plant-derived water-soluble solvent. Examples of the plant-derived water-soluble solvent include glycerin.

[0033] The water-based ink may further include, for example, a surfactant.

[0034] The surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, a commercially available product may be used. Specific examples of the surfactant include silicone-based surfactants and acetylene-based surfactants.

[0035] Examples of commercially available silicone surfactants include "Silface (registered trademark) SAG002", "Silface (registered trademark) SAG005", and "Silface (registered trademark) SAG503A" manufactured by Nissin Chemical Industry Co., Ltd.

[0036] Examples of commercially available acetylene surfactants include "Olfine (registered trademark) E1004", "Olfine (registered trademark) E1008", and "Olfine (registered trademark) E1010" manufactured by Nissin Chemical Industry Co., Ltd.; "Surfynol (registered trademark) 440", "Surfynol (registered trademark) 465", and "Surfynol (registered trademark) 485" manufactured by Air Products and Chemicals, Inc.; and "Acetylenol (registered trademark) E40" and "Acetylenol (registered trademark) E100" manufactured by Kawaken Fine Chemicals Co., Ltd.

[0037] The water-based ink may contain other surfactants in addition to or in place of the silicone-based surfactant and the acetylene-based surfactant. Examples of the other surfactants include nonionic surfactants "EMULGEN (registered trademark)" series, "RHEODOL (registered trademark)" series, "EMASOL (registered trademark)" series, "EXCEL (registered trademark)" series, "EMANON (registered trademark)" series, "AMIET (registered trademark)" series, and "AMINON (registered trademark)" series manufactured by Kao Corporation; nonionic surfactants "SORBON (registered trademark)" series manufactured by Toho Chemical Industry Co., Ltd.; nonionic surfactants "DOBANOX (registered trademark)" series, "LEOCOL (registered trademark)" series, "LEOX (registered trademark)" series, "LAOL,LEOCOL (registered trademark)" series, "LIONOL (registered trademark)" series, "CADENAX (registered trademark)" series, "LIONON (registered trademark)" series, and "LEOFAT (registered trademark)" series manufactured by Lion Corporation; anionic surfactants "EMAL (registered trademark)" series, "LATEMUL (registered trademark)" series, "VENOL (registered trademark)" series, "NEOPELEX (registered trademark)" series, NS SOAP, KS SOAP, OS SOAP and the "PELEX (registered trademark)" series, etc.; anionic surfactants manufactured by Lion Corporation, such as the "LIPOLAN (registered trademark)" series, "LIPON (registered trademark)" series, "SUNNOL (registered trademark)" series, "LIPOTAC (registered trademark) TE, ENAGICOL" series, "LIPAL (registered trademark)" series, and "LOTAT (registered trademark)" series, etc.; cationic surfactants manufactured by Daiichi Kogyo Seiyaku Co., Ltd., such as "Katiogen (registered trademark) ES-OW" and "Katiogen (registered trademark) ES-L", etc.

[0038] The surfactants may be used alone or in combination of two or more kinds.

[0039] The water-based ink may further contain conventionally known additives as necessary. Examples of the additives include a pH adjuster, a viscosity adjuster, a surface tension adjuster, and a mold inhibitor. Examples of the viscosity adjuster include polyvinyl alcohol, cellulose, and a water-soluble resin.

[0040] <Inkjet recording apparatus and inkjet recording method> Next, the ink jet recording apparatus and the ink jet recording method of the present invention will be described.

[0041] The inkjet recording apparatus of the present invention includes an ink flow path and an ink ejection means, and is characterized in that the water-based ink for inkjet recording of the present invention, which is supplied to the ink flow path, is ejected onto a recording medium by the ink ejection means.

[0042] The configuration of one example of an inkjet recording device of the present invention is shown in Figure 1. As shown in the figure, this inkjet recording device 1 includes, as main components, four ink storage units (ink cartridges 2), an ink ejection unit (inkjet head) 3, a head unit 4, a carriage 5, a drive unit 6, a platen roller 7, and a purge device 8.

[0043] The four ink cartridges 2 each contain one of the four water-based inks of yellow, magenta, cyan, and black. For example, at least one of the four water-based inks is the water-based ink of the present invention. In this example, a set of four ink cartridges 2 is shown, but instead of this, an integrated ink cartridge whose interior is partitioned to form a water-based yellow ink storage section, a water-based magenta ink storage section, a water-based cyan ink storage section, and a water-based black ink storage section may be used. As the main body of the ink cartridge, for example, a conventionally known one may be used.

[0044] The inkjet head 3 mounted on the head unit 4 performs recording on a recording medium P. The recording medium P is not particularly limited, but examples thereof include plain paper and glossy paper. The carriage 5 is mounted with four ink cartridges 2 and the head unit 4. The drive unit 6 moves the carriage 5 back and forth in a linear direction. As the drive unit 6, for example, a conventionally known one can be used (for example, see JP 2008-246821 A). The platen roller 7 extends in the reciprocating direction of the carriage 5, and is disposed opposite the inkjet head 3.

[0045] The inkjet head 3 is formed, for example, by stacking multiple thin metal plates. Each thin plate has a through hole. A flow path for passing the water-based ink is formed by stacking multiple thin plates with through holes. The thin plates are bonded to each other, for example, by an adhesive.

[0046] The purging device 8 sucks up defective ink containing air bubbles and the like that accumulates inside the inkjet head 3. As the purging device 8, for example, a conventionally known device can be used (for example, see JP-A-2008-246821).

[0047] A wiper member 20 is disposed adjacent to the purging device 8 on the platen roller 7 side of the purging device 8. The wiper member 20 is formed in a spatula shape, and wipes the nozzle formation surface of the inkjet head 3 as the carriage 5 moves. In Fig. 1, a cap 18 covers the multiple nozzles of the inkjet head 3, which are returned to a reset position when recording is completed, in order to prevent the water-based ink from drying.

[0048] In the inkjet recording device 1 of this embodiment, the four ink cartridges 2 are mounted on one carriage 5 together with the head unit 4. However, the present invention is not limited to this. In the inkjet recording device 1, each of the four ink cartridges 2 may be mounted on a carriage separate from the head unit 4. Also, each of the four ink cartridges 2 may not be mounted on the carriage 5, but may be arranged and fixed within the inkjet recording device 1. In these embodiments, for example, each of the four ink cartridges 2 and the head unit 4 mounted on the carriage 5 are connected by a tube or the like, and the water-based ink is supplied from each of the four ink cartridges 2 to the head unit 4. Also, in these embodiments, four bottle-shaped ink bottles may be used instead of the four ink cartridges 2. In this case, it is preferable that the ink bottle is provided with an injection port for injecting ink from the outside into the inside.

[0049] Inkjet recording using this inkjet recording apparatus 1 is carried out, for example, as follows. First, recording paper P is fed from a paper feed cassette (not shown) provided to the side or below the inkjet recording apparatus 1. The recording paper P is introduced between the inkjet head 3 and the platen roller 7. A predetermined recording is made on the introduced recording paper P using water-based ink ejected from the inkjet head 3. After recording, the recording paper P is discharged from the inkjet recording apparatus 1. In FIG. 1, the paper feed mechanism and paper discharge mechanism for the recording paper P are not shown.

[0050] The device shown in FIG. 1 employs a serial type inkjet head, but the present invention is not limited thereto. The inkjet recording device may employ a line type inkjet head or a roll-to-roll system. The serial type inkjet head is an inkjet head that prints while reciprocating in the width direction of the recording medium. The line type inkjet head is an inkjet head that covers the entire width direction of the recording medium. The roll-to-roll system is a system in which a roll-shaped recording medium is unwound, printed on, and then wound up into a roll again.

[0051] Next, the inkjet recording method of the present invention includes a recording step, which includes a step of applying an aqueous ink to a recording medium by an inkjet method to perform recording, and the aqueous ink is the aqueous ink for inkjet recording of the present invention. The inkjet recording method of the present invention can be carried out, for example, by using the inkjet recording device of the present invention. The recording includes printing, photographic printing, printing, etc. The recording medium P is not particularly limited, but examples thereof include plain paper, glossy paper, etc. EXAMPLES

[0052] Next, examples of the present invention will be described together with comparative examples. Note that the present invention is not limited or restricted by the following examples and comparative examples.

[0053] (Preparation of Pigment Dispersion A) 40 g of carbon black "#2650 (trade name)" manufactured by Mitsubishi Chemical Corporation was mixed with 200 g of ion-exchanged water and pulverized in a bead mill. A carboxyl base agent was added to the mixture, and the mixture was heated and stirred to carry out an oxidation treatment. The resulting liquid was then washed several times with a solvent, poured into water, and after repeated water washing, filtered with a filter to obtain pigment dispersion liquid A. The average particle size of the carbon black contained in this pigment dispersion liquid A was measured using "LB-550 (trade name)" manufactured by Horiba, Ltd., and was found to be 153 nm.

[0054] (Preparation of Pigment Dispersion B) Pure water was added to 20% by mass of pigment (CI Pigment Yellow 74) and 7% by mass of styrene-acrylic acid copolymer neutralized with sodium hydroxide (acid value 50 mgKOH / g, molecular weight 10,000) to make the total 100% by mass, and the mixture was stirred and mixed to obtain a mixture. This mixture was placed in a wet sand mill filled with 0.3 mm diameter zirconia beads and subjected to a dispersion treatment for 6 hours. Thereafter, the zirconia beads were removed using a separator, and the mixture was filtered through a cellulose acetate filter with a pore size of 3.0 μm to obtain pigment dispersion B. The styrene-acrylic acid copolymer is a water-soluble polymer that is generally used as a dispersant for pigments.

[0055] (Examples 1 to 8, Comparative Examples 1 to 5) The components in the aqueous ink composition in Table 1 below, except for the coloring material (colorant), were mixed uniformly to obtain an ink solvent. Next, the coloring material was added to the ink solvent and mixed uniformly. The mixture obtained was then filtered through a cellulose acetate type membrane filter (pore size 3.00 μm) manufactured by Toyo Roshi Kaisha, Ltd., to obtain aqueous inks for inkjet recording of Examples 1 to 8 and Comparative Examples 1 to 5 shown in Table 1.

[0056] The water-based inks of Examples 1 to 8 and Comparative Examples 1 to 5 were evaluated for (a) glossy paper fixation, (b) viscosity, (c) IJ dischargeability, and (d) environmental friendliness by the following methods.

[0057] (a) Fixability on glossy paper Using an inkjet recording device manufactured by Brother Industries, Ltd. (product name: DCP-J987N), solid images of 0.8 cm in length were recorded on glossy paper (manufactured by Brother Industries, Ltd., product name: BP71GA4) using the water-based inks of Examples 1 to 8 and Comparative Examples 1 to 5, to prepare evaluation samples. A non-recorded area was provided outside the solid image recording area. 10 seconds after recording each water-based ink on the glossy paper, the recording surface was scanned with an 8×10 3The solid image was rubbed with a cotton swab to which a load of 100 Pa was applied. The rubbing with the cotton swab was performed from the top end to the bottom end in the length direction of the solid image, up to the non-recorded part outside the recorded part of the solid image. After rubbing with the cotton swab, the degree of dirt on the non-recorded part from the bottom end of the recorded surface (the length of dirt on the non-recorded part) was evaluated according to the following evaluation criteria.

[0058] Glossy paper fixation evaluation criteria A: Dirt less than 5mm from the bottom edge of the recording surface B: Dirt 5mm or more from the bottom edge of the recording surface

[0059] (b) Viscosity The water-based inks of Examples 1 to 8 and Comparative Examples 1 to 5 were measured at 25° C. using a viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TVE-25 model) and evaluated according to the following evaluation criteria.

[0060] Viscosity Evaluation Criteria A: Viscosity less than 10.0 mPa s B: Viscosity 10.0mPa·s or more

[0061] (c) IJ ejection performance Using an inkjet recording device manufactured by Brother Industries, Ltd. (product name: DCP-J987N, suitable viscosity: 10 mPa s), solid images were recorded on glossy paper (manufactured by Brother Industries, Ltd., product name: BP71GA4) using the water-based inks of Examples 1 to 8 and Comparative Examples 1 to 5 to prepare evaluation samples. The state of ejection of the water-based ink from each ejection channel (ch) was evaluated according to the following evaluation criteria.

[0062] Inkjet discharge performance evaluation criteria A: Discharged from all channels B: No discharge in some channels C: Water-based ink could not be ejected

[0063] (d) Environmental friendliness The water-based inks of Examples 1 to 8 and Comparative Examples 1 to 5 were evaluated according to the following evaluation criteria.

[0064] Environmental friendliness evaluation criteria ○: Contains plant-derived materials as fixing agent ×: Contains petroleum-derived materials as fixing agent

[0065] Table 1 shows the compositions and evaluation results of the water-based inks of Examples 1 to 8 and Comparative Examples 1 to 5.

[0066] [Table 1]

[0067] As shown in Table 1, the environmental compatibility and viscosity evaluations of Examples 1 to 8 were "○". In addition, the glossy paper fixation and IJ dischargeability were all evaluated as "B" or higher, and the properties of the water-based ink were improved.

[0068] In addition, in Examples 3 and 4, which used a self-dispersed pigment and had a polysaccharide solids content of 4.0 to 17.0% by weight, glossy paper fixation and IJ dischargeability were all rated as "A" or higher. Similarly, in Examples 1 and 2, which used a resin-dispersed pigment and had a polysaccharide solids content of 4.0 to 14.0% by weight, glossy paper fixation and IJ dischargeability were all rated as "A" or higher.

[0069] On the other hand, Comparative Examples 1 and 2, which contain petroleum-derived materials as fixing agents, were rated as "X" in terms of environmental compatibility. Comparative Examples 3 and 4 (examples containing glucomannan), which contain polysaccharides other than xylan, were unable to eject aqueous ink from the inkjet head. Furthermore, Comparative Example 5, in which "a / b" is 0.5 or more, was also unable to eject aqueous ink from the inkjet head.

[0070] A part or all of the above-described embodiments and examples may be described as follows, but is not limited to the following. (Appendix 1) A water-based ink for ink-jet recording, comprising: The water-based ink comprises water, a colorant, and a polysaccharide; The polysaccharide contains at least one of xylan and a derivative thereof, The viscosity of the water-based ink at 25°C is less than 10 mPa s. Water-based ink for inkjet recording. (Appendix 2) 2. The aqueous ink for ink-jet recording according to claim 1, wherein the polysaccharide comprises the xylan. (Appendix 3) 3. The aqueous ink for ink-jet recording according to claim 1, wherein the content of the water is greater than the contents of each of the other components by weight of the entire aqueous ink. (Appendix 4) 4. The water-based ink for ink-jet recording according to claim 3, wherein a content ratio (a / b) of a sum (a) of a solid content of the colorant and a solid content of the polysaccharide to a content (b) of the water is less than 0.5. (Appendix 5) 5. The water-based ink for ink-jet recording according to claim 1, wherein the colorant is a pigment. (Appendix 6) The pigment is a self-dispersing pigment, 6. The aqueous ink for ink-jet recording according to any one of claims 1 to 5, wherein the solid content of the polysaccharide is 4.0 to 17.0% by weight based on the total weight of the aqueous ink. (Appendix 7) The pigment is a resin-dispersed pigment, 6. The aqueous ink for ink-jet recording according to any one of claims 1 to 5, wherein the solid content of the polysaccharide is 4.0 to 14.0% by weight based on the total weight of the aqueous ink. (Appendix 8) An ink flow path and an ink ejection means are included. The water-based ink for ink-jet recording according to any one of claims 1 to 7, which has been supplied to the ink flow path, is discharged onto a recording medium by the ink discharge means. Inkjet recording device. (Appendix 9) A recording step is included. the recording step includes a step of applying a water-based ink to a recording medium by an inkjet method to perform recording; The aqueous ink is an aqueous ink for ink-jet recording according to any one of claims 1 to 7. Inkjet recording method. [Industrial Applicability]

[0071] As described above, according to the present invention, it is possible to provide an aqueous ink for inkjet recording in which a part of the petroleum-derived raw materials is replaced with plant-derived raw materials while maintaining the same performance as conventional aqueous inks for inkjet recording. The aqueous ink, inkjet recording apparatus, and inkjet recording method of the present invention can be widely used for inkjet recording on various recording media. [Explanation of symbols]

[0072] 1 Inkjet recording device 2 Ink cartridges 3. Ink ejection section (inkjet head) 4 Head Unit 5 Carriage 6 Drive unit 7 Platen roller 8 Purging device

Claims

1. A water-based ink for ink-jet recording, comprising: The water-based ink comprises water, a colorant, and a polysaccharide; The polysaccharide contains at least one of xylan and a derivative thereof, The viscosity of the aqueous ink at 25° C. is less than 10 mPa·s. Water-based ink for inkjet recording.

2. The water-based ink for ink-jet recording according to claim 1 , wherein the polysaccharide comprises the xylan.

3. 2. The water-based ink for ink-jet recording according to claim 1, wherein the content of said water is greater than the contents of each of the other constituent components in the total weight of said water-based ink.

4. 4. The water-based ink for ink-jet recording according to claim 3, wherein a content ratio (a / b) of a sum (a) of a solid content of the colorant and a solid content of the polysaccharide to a content (b) of the water is less than 0.

5.

5. 2. The water-based ink for ink-jet recording according to claim 1, wherein the colorant is a pigment.

6. The pigment is a self-dispersing pigment, 6. The water-based ink for ink-jet recording according to claim 5, wherein the solid content of the polysaccharide is 4.0 to 17.0% by weight based on the total weight of the water-based ink.

7. The pigment is a resin-dispersed pigment, 6. The water-based ink for ink-jet recording according to claim 5, wherein the solid content of the polysaccharide is 4.0 to 14.0% by weight based on the total weight of the water-based ink.

8. An ink flow path and an ink ejection means are included. The water-based ink for ink-jet recording according to claim 1 , which has been supplied to the ink flow path, is ejected onto a recording medium by the ink ejection means. Inkjet recording device.

9. A recording step is included. the recording step includes a step of applying a water-based ink to a recording medium by an inkjet method to perform recording; The aqueous ink is the aqueous ink for ink-jet recording according to any one of claims 1 to 7. Inkjet recording method.

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