Ink jet recording method and recording apparatus

Abstract

To provide an inkjet recording method excellent in discharge stability.SOLUTION: An ink jet recording method comprising: bringing an outer surface of an ink accommodation body having an ink jet ink composition containing a pigment into contact with a magnet; and discharging the ink jet ink composition from an ink jet head and attaching the ink jet ink composition to a recording medium.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording method and a recording apparatus. [Background technology]

[0002] Inkjet recording methods are capable of recording high-resolution images using relatively simple equipment, and have been rapidly developing in various fields. In the process, various studies have been conducted on ejection stability, etc. For example, Patent Document 1 discloses an ink tank that is composed of a flexible, sealed container that is vacuum-filled with ink, and that rotatably houses a rotor having one or more steel balls or permanent magnets, in order to prevent air bubbles from entering the ink and causing ejection failures. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-212336 Summary of the Invention [Problem to be solved by the invention]

[0004] However, minute metal particles may be mixed in during the process of pulverizing the coloring material contained in the ink, and aggregates may be generated, and there has been insufficient research into how to prevent non-ejection due to this. [Means for solving the problem]

[0005] The inkjet recording method of the present invention includes a contacting step of bringing a magnet into contact with the outer surface of an ink container having an inkjet ink composition containing a pigment, and a discharging step of discharging the inkjet ink composition from an inkjet head and causing it to adhere to a recording medium.

[0006] The inkjet recording apparatus of the present invention comprises an ink container having an inkjet ink composition containing a pigment, a magnet in contact with the outer surface of the ink container, and an inkjet head that ejects the inkjet ink composition. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram illustrating an example of an ink container used in the recording method of the present embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of an ink container used in the recording method of the present embodiment. [Figure 3] FIG. 1 illustrates an example of a recording apparatus according to an embodiment of the present invention. [Figure 4] Table 1 shows the details of the conditions for the recording method of the example and the evaluation results thereof. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. In the drawings, the same elements are given the same reference numerals, and redundant explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0009] Conventionally, when preparing an ink composition containing a colorant, the colorant is pulverized and dispersed using a bead mill or homogenizer. However, wear on the equipment during this process can lead to the contamination of the ink with fine metal particles that are not originally intended for the ink composition. Such contamination by metal particles forms aggregates within the ink composition, reducing ejection stability. After extensive research, we have found that an inkjet recording method that includes a contact step of contacting a magnet with the outer surface of an ink container containing a pigment-containing inkjet ink composition can achieve excellent ejection stability. This is believed to be due to the fact that contacting the outer surface of the ink container with the magnet traps the metal particles in a portion of the ink container, preventing the metal particles from leaking into the flow path and suppressing the formation of aggregates of metal particles in the flow path and head, resulting in a recording method with excellent ejection stability.

[0010] The inkjet recording method and recording apparatus of this embodiment will be described in detail below.

[0011] <Inkjet recording method> The inkjet recording method according to this embodiment (hereinafter also simply referred to as "this recording method") comprises a contacting step of bringing a magnet into contact with the outer surface of an ink container having an inkjet ink composition containing a pigment, and a discharging step of discharging the inkjet ink composition from an inkjet head and causing it to adhere to a recording medium.

[0012] 1.Contact process The present recording method can be made to have excellent ejection stability by including a contacting step of bringing the outer surface of an ink container holding an inkjet ink composition containing a pigment into contact with a magnet.

[0013] 1.1.Ink container The ink container of the present recording method contains an ink composition and has a magnet attached to its outer surface. By using such an ink container, the present recording method exhibits excellent ejection stability.

[0014] 1 and 2 show an example of an ink container used in this recording method. For example, in FIG. 1, a magnet 2 is attached to a portion of the surface of an ink pack 1, which is an ink container. The magnet 2 does not necessarily have to be a single magnet 2; multiple magnets 2 may be attached. Also, in FIG. 2, a magnet 2' is attached to a portion of the surface of an ink bottle 3, which is an ink container. As shown in FIG. 2, the attachment position of the magnets 2' and the number of magnets 2' attached are not particularly limited.

[0015] The amount of ink composition contained in the ink container during the contacting step is not particularly limited, but is preferably, for example, 100 mL to 5000 mL. By using such an amount of ink composition, the effect of improving ejection stability during the contacting step tends to be more effective and reliable. From the same perspective, the amount of ink composition contained in the ink container is more preferably 200 mL to 4000 mL, and even more preferably 300 mL to 3000 mL.

[0016] 1.2.Magnets The magnet is not limited as long as it can generate a magnetic field, but from the viewpoint of productivity, it is preferable to use a permanent magnet. A single magnet with a large area may be used, or multiple magnets with relatively small areas may be used. The type of magnet is not particularly limited, but neodymium magnets, samarium-cobalt magnets, ferrite magnets, alnico magnets, etc. are preferred.

[0017] In the contact process, the total contact area S between the magnet and the outer surface is 10 cm 2 When the total contact area S is within the above range, the effect of improving the ejection stability according to the present invention tends to be more effective and reliable. From the same viewpoint, the total contact area S is preferably 15 cm 2 More preferably, 20cm or more 2 More preferably, it is 50cm or more. 2 The upper limit of the total contact area S is not particularly limited as long as it is equal to or smaller than the area of ​​the outer surface of the ink container, but it is preferably 500 cm or less, for example. 2It may be 300cm 2 may be.

[0018] In the contact step, the treatment time T during which the ink composition is exposed to the magnetic field generated by the magnet is preferably 10 minutes or longer. By setting the treatment time T at such a time, the metal microparticles are more reliably captured by the magnet, and ejection stability tends to be improved. From the same perspective, the treatment time T is more preferably 20 minutes or longer, and even more preferably 50 minutes or longer. Furthermore, the upper limit of the treatment time T is not particularly limited, but may be 60 minutes or shorter.

[0019] In the contact process, the value A, which indicates the degree of contact with the magnet per unit of ink volume, is calculated using the following formula: 2 / mL] or more. When the value A is within the above range, the effect of improving the ejection stability according to the present invention tends to be more effective and reliable. From the same viewpoint, the value A is preferably 5 [min cm 2 / mL] or more is more preferable. 2 / mL] or more is more preferable, and [min·cm 2 / mL] or more, 10 [min·cm 2 / mL] or more is even more preferable, and 15 [min·cm 2 The upper limit of the value A is not particularly limited, and is, for example, 500 [min cm 2 / mL], and 100 [min·cm 2 / mL] may also be used.

number

[0020] The ratio of the total contact area S of the magnet to the amount I of the ink composition (S / I) is 0.001 cm 2 / mL] or more. By setting the ratio (S / I) within the above range, the effect of improving the ejection stability according to the present invention tends to be more effective and reliable. From the same viewpoint, the ratio (S / I) is preferably 0.005 [cm 2 / mL] or more is more preferable, and 0.01 [cm 2 / mL] or more is more preferable, and 0.05 [cm 2 The upper limit of the ratio (S / I) is not particularly limited, and is, for example, 0.5 [cm 2 / mL], and 0.3 [cm 2 / mL] may also be used.

[0021] The magnetic flux density of the magnet used is preferably 100 mT or more. When the magnetic flux density of the magnet is within the above range, the effect of improving the ejection stability of the present invention tends to be effectively and reliably achieved. From the same viewpoint, the magnetic flux density is more preferably 200 mT or more. The upper limit of the magnetic flux density is not particularly limited, and may be, for example, 5 T or 3 T.

[0022] The distance between the magnet in contact with the outer surface of the ink container and the ink composition, i.e., the thickness of the peripheral wall of the ink container to which the magnet is attached, is preferably 10 mm or less. By keeping the peripheral wall thickness within this range, the effect of improving ejection stability according to the present invention tends to be effectively and reliably achieved. From the same perspective, the thickness of the peripheral wall of the ink container to which the magnet is attached is more preferably 5 mm or less, and even more preferably 3 mm or less. The lower limit of the peripheral wall thickness is not particularly limited and may be, for example, 0.1 mm or 0.3 mm.

[0023] 1.3. Inkjet ink composition The inkjet ink composition (hereinafter also simply referred to as "ink composition") used in the present recording method contains a pigment and may contain other components that can be contained in an ink composition, as necessary. In the case of a radiation-curable ink composition, examples of other components include a polymerizable compound, a photopolymerization initiator, and a dispersant. In the case of an aqueous ink composition, examples of other components include an organic solvent, water, a surfactant, and amines. From the perspective of more effectively and reliably achieving the effects of the present invention, a radiation-curable ink composition is preferred as the ink composition.

[0024] 1.3.1.Pigments Pigments may contain metal particles during the process of pulverization and dispersion using a bead mill or homogenizer. Taking this into consideration, the volume average particle diameter (D50) of the pigment is preferably 50 nm or more and 400 nm or less. Using a pigment with an average particle diameter within this range facilitates the incorporation of fine metal particles into the pigment, tending to more effectively and reliably achieve the effects of the present invention. From the same perspective, the volume average particle diameter (D50) of the pigment is more preferably 60 nm or more and 350 nm or less, and even more preferably 70 nm or more and 300 nm or less. The volume average particle diameter (D50) in this specification is the D50 value measured by dynamic light scattering.

[0025] Examples of pigments include inorganic pigments and organic pigments. One type of pigment may be used alone, or two or more types may be used in combination. As the inorganic pigment, carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, and titanium oxide can be used.

[0026] Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye chelates (for example, basic dye chelates, acid dye chelates, etc.); dye lakes (basic dye lakes, acid dye lakes), nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments.

[0027] The pigment preferably contains at least one selected from the group consisting of cyan, magenta, yellow, black, and white. By containing such a pigment, the effects of the present invention tend to be more effective and reliable. From the same viewpoint, it is more preferable that the pigment in the present recording method contains at least magenta.

[0028] Cyan pigments include, for example, CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:34, 15:4, 16, 18, 22, 25, 60, 65, 66, or CI Vat Blue 4, 60.

[0029] Examples of magenta pigments include CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48(Ca), 48(Mn), 57(Ca), 57:1, 88, 112, and 114. , 122, 123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or CI Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50.

[0030] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, and 120.

[0031] Examples of black pigments include No. 2200B (trade name, manufactured by Mitsubishi Chemical Corporation), Raven 700 (trade name, manufactured by Carbon Columbia), and Monarch 1400 (trade name, manufactured by CABOT JAPAN KK).

[0032] Examples of white pigments include CI Pigment White 6, 18, and 21.

[0033] Other pigments include, for example, CI Pigment Green 7, 10, or CI Pigment Brown 3, 5, 25, 26, or CI Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

[0034] The pigment content is preferably 0.1% by mass or more and 15.0% by mass or less, based on the total amount of the ink composition. By keeping the pigment content within this range, the effects of the present invention tend to be more effectively and reliably achieved. From the same perspective, the pigment content is more preferably 0.3% by mass or more and 10.0% by mass or less, and even more preferably 0.5% by mass or more and 5.0% by mass or less.

[0035] 1.3.2. Polymerizable compounds The polymerizable compound is a base monomer that is included when preparing the dispersion and the ink. The polymerizable compound may be, for example, a photopolymerizable compound that polymerizes and solidifies when irradiated with light such as ultraviolet light. The polymerizable compound is not particularly limited, but examples thereof include monofunctional monomers, bifunctional monomers, and trifunctional or higher polyfunctional monomers. One type of polymerizable compound may be used alone, or two or more types may be used in combination.

[0036] The polymerizable monomer is not particularly limited, but examples thereof include benzyl (meth)acrylate, isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. From the viewpoint of more effectively and reliably achieving the effect of improving discharge stability according to the present invention, it is preferable to include one or more, and more preferably two or more, selected from the group consisting of phenoxyethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, and dipropylene glycol diacrylate.

[0037] The content of the polymerizable compound is preferably 60% by mass or more and 95% by mass or less, based on the total amount of the ink composition. By keeping the content of the polymerizable compound within this range, the effect of improving the ejection stability of the present invention tends to be more effective and reliable. From the same viewpoint, the content is more preferably 70% by mass or more and 92% by mass or less, and even more preferably 75% by mass or more and 90% by mass or less.

[0038] 1.3.3. Photopolymerization initiator A photopolymerization initiator (also simply referred to as "initiator") generates active species (initiation species) such as radicals, acids, and bases when irradiated with radiation, and promotes the polymerization reaction of monomers through the function of the initiation species. Note that one type of photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0039] Examples of the photopolymerization initiator include known photopolymerization initiators such as acylphosphine oxide-based photopolymerization initiators and thioxanthone-based photopolymerization initiators. Commercially available photopolymerization initiators include, for example, IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethan-1-one), IRGACURE 184 (1-hydroxycyclohexylphenyl ketone), DAROCURE 1173 (2-hydroxy-2-methyl-1-phenylpropan-1-one), DAROCURE TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide), IRGACURE 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide), Speedcure TPO, Speedcure DETX (2,4-diethylthioxanthone), Speedcure ITX (2-isopropylthioxanthone) (all manufactured by Lambson), and KAYACURE DETX-S (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.). Among these, from the viewpoint of more effectively and reliably achieving the effect of improving the ejection stability according to the present invention, it is preferable to use one or more selected from the group consisting of IRGACURE 819, DAROCURE TPO, and KAYACURE DETX-S.

[0040] The content of the photopolymerization initiator is preferably 5% by mass or more and 20% by mass or less, based on the total amount of the ink composition. By setting the content of the photopolymerization initiator within this range, the effect of improving the ejection stability of the present invention tends to be more effective and reliable. From the same viewpoint, the content is more preferably 7% by mass or more and 18% by mass or less, and even more preferably 10% by mass or more and 15% by mass or less.

[0041] Dispersants The dispersant is a solvent for dispersing the pigment. The dispersant is not particularly limited, but examples thereof include dispersants containing one or more of polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxy resins as a main component.

[0042] Commercially available dispersants include the Ajisper series manufactured by Ajinomoto Fine-Techno Co., Ltd., the Solsperse series available from Avecia Co. (Solsperse 36000 (acid value 45), Solsperse 32000 (amine value 35), etc.), the Disperbyk series manufactured by BYK Chemie (DISPERBYK 168, 180, etc.), and the Disparlon series manufactured by Kusumoto Chemicals Co., Ltd. Of these, Solsperse 36000 is preferred from the viewpoint of more effectively and reliably achieving the effect of improving discharge stability according to the present invention.

[0043] The content of the dispersant is preferably 0.05% by mass or more and 3.0% by mass or less, based on the total amount of the ink composition. When the content of the dispersant is within the above range, the effect of improving the ejection stability of the present invention tends to be more effective and reliable. From the same viewpoint, the content of the dispersant is more preferably 0.1% by mass or more and 2.0% by mass or less, and even more preferably 0.5% by mass or more and 1.5% by mass or less.

[0044] In addition to the above components, the ink composition may contain other components that can be used in conventional inks, as needed. Examples of such components include, but are not limited to, slip agents, solubilizers, viscosity adjusters, pH adjusters, antioxidants, preservatives, and corrosion inhibitors. The other components may be used alone or in combination of two or more. The content of the other components may be, for example, 5% by mass or less, 3% by mass or less, or 1% by mass or less, based on the total amount of the ink composition.

[0045] 2.Discharge process The present recording method includes a discharge step of discharging the ink composition from an inkjet head to adhere it to a recording medium.

[0046] Inkjet heads used in the ejection step include a line head that performs recording by a line method and a serial head that performs recording by a serial method. In the line method using a line head, for example, an inkjet head having a width equal to or greater than the recording width of the recording medium is fixed to the inkjet device. The recording medium is then moved in the sub-scanning direction (the longitudinal direction of the recording medium, the transport direction), and ink droplets are ejected from the nozzles of the inkjet head in conjunction with this movement to record an image on the recording medium.

[0047] In the serial method using a serial head, for example, an inkjet head is mounted on a carriage that can move in the width direction of the recording medium. The carriage is then moved in the main scanning direction (the horizontal or width direction of the recording medium), and ink droplets are ejected from the nozzle openings of the head in conjunction with this movement, thereby recording an image on the recording medium.

[0048] Examples of recording media include absorbent recording media, low-absorbent recording media, and non-absorbent recording media. Absorbent recording media include inkjet paper, plain paper, and fabric. Low-absorbent recording media include, but are not limited to, coated paper having a coating layer on the surface for receiving oil-based ink. Coated paper includes, but is not limited to, printing paper such as art paper, coated paper, and matte paper. Non-absorbent recording media include, but are not limited to, recording media coated with a plastic film such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), or polycarbonate.

[0049] <Inkjet recording device> The inkjet recording apparatus according to this embodiment (hereinafter simply referred to as "the recording apparatus") comprises an ink container containing an inkjet ink composition containing a pigment, a magnet in contact with the outer surface of the ink container, and an inkjet head that ejects the inkjet ink composition. By using an inkjet recording apparatus having such a configuration, ejection failures due to aggregates formed by metal fine particles can be suppressed, and ejection stability can be improved. Details and preferred aspects of the ink composition, ink container, magnet, inkjet head, etc. used in the recording apparatus can be the same as those in the recording method described above, in the same preferred aspects.

[0050] As an example of this recording apparatus, a schematic diagram of a line printer is shown in FIG. 3. As shown in FIG. 3, the inkjet recording apparatus 100 includes an irradiation unit 10, an inkjet head 20, and a transport section 30. In the line-type inkjet recording apparatus 100, a recording medium M is transported from the transport section 30 in a transport direction F, and the ink composition that has been subjected to the contact process of this embodiment is ejected from the inkjet head 20 onto the recording surface of the recording medium M. The ink irradiated surface 12 that has landed on the recording medium M is then transported further in the transport direction F, where it is irradiated with light by the irradiation unit 10 and cured. The ink is then wound up and stored in the transport section 30 at the end of the transport direction F. This recording apparatus, which has excellent ejection stability, is particularly suitable for continuous recording, as shown in FIG. 3, in which the recording medium M is immediately collected after each process is performed.

[0051] The inkjet device 100 may have an air outlet 11. By blowing an inert gas through the air outlet 11, the oxygen concentration in the atmosphere can be reduced, thereby improving the curability of the coating film. The inert gas may be a known inert gas such as a rare gas or nitrogen gas, and nitrogen or argon is more preferred. The inkjet device 100 may have an irradiation unit 12. Furthermore, if the distance between the air outlet 11 and the recording medium M in the direction from the air outlet 11 toward the recording medium M is h1, and the distance between the irradiation unit 12 and the recording medium M in the direction from the air outlet 11 toward the recording medium M is h2, it is more preferable that h1 be greater than h2. When h1 is greater than h2, the inert gas blown from the air outlet 11 is more likely to remain around the air outlet 11, which makes it possible to reduce the oxygen concentration in the atmosphere and improves the curability of the coating film. [Example]

[0052] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0053] FIG. 4 shows Table 1, which shows the composition of each composition of the examples and comparative examples and the evaluation results thereof.

[0054] 1. Preparation of Ink Composition The components were placed in a mixing tank so as to obtain the following composition, and the mixture was mixed and stirred, followed by filtration through a membrane filter to obtain the inkjet ink composition of each example. The numerical value of each component is based on 100% by mass of the ink composition.

[0055] The details of the components used are as follows: [Colorant] CI Pigment Red 122 (2% by weight, magenta pigment, D50: 140 μm) [Polymerizable compound] PEA (30% by mass, phenoxyethyl acrylate, product name "Viscoat #192", manufactured by Osaka Organic Chemical Industry Ltd.) VEEA (20% by mass, product name of 2-(2-vinyloxyethoxy)ethyl acrylate, manufactured by Nippon Shokubai Co., Ltd.) DPGDA (35% by mass, dipropylene glycol diacrylate, product name "APG-100", manufactured by Shin-Nakamura Chemical Co., Ltd.) [Photopolymerization initiator] IRGACURE 819 (6% by mass, product name, manufactured by BASF Japan Ltd.) DAROCURE TPO (4% by mass, product name, manufactured by BASF Japan Ltd.) KAYACURE DETX-S (2% by mass, product name, manufactured by Nippon Kayaku Co., Ltd.) [Dispersant] Solsperse 36000 (1% by mass, product name, manufactured by Lubrizol Japan Co., Ltd.)

[0056] 2.Contact process Each of the ink compositions prepared in Examples 1 to 12 was placed in an ink container to which a magnet having the magnetic flux density and total contact area S shown in Table 1 was attached. After leaving the ink composition in the container for a treatment time T, the ink composition was removed and transferred to a sample bottle for analysis. Note that the contact step was not carried out for Comparative Example 1.

[0057] 3. Evaluation method for ejection stability After carrying out the following treatment, the content of metal flakes (Fe) contained in the ink composition before and after the contact step was measured by ICP atomic emission spectroscopy (ICP-AES). First, to eliminate concentration differences due to the settling of metal fragments, the sample bottle containing the sample was manually shaken vertically 50 times and upside down 50 times, and then immediately weighed. Sulfuric acid was added to the weighed sample, followed by heating, carbonization, and heating, followed by ashing. The resulting ash was thermally decomposed with sulfuric acid and hydrofluoric acid, melted with potassium hydrogen sulfate, and then dissolved in dilute nitric acid to a constant volume. The metal fragments (Fe) in this solution were measured using the above-mentioned analyzer to determine the metal fragment content in the sample. An ICP optical emission spectrometer (PS3520VDDII, manufactured by Hitachi High-Tech Science Corporation) was used as the analyzer. Discharge stability was evaluated according to the following evaluation criteria. Ink compositions rated S, A, and B had lower metal content than those rated C and D, and therefore had better discharge stability. (Evaluation criteria) S: Metal fragments detected at less than 0.1 ppm A: Metal fragments were detected at 0.1 ppm or more but less than 0.4 ppm. B: Metal fragments were detected at 0.4 ppm or more but less than 0.9 ppm. C: Metal fragments were detected at 0.9 ppm or more but less than 1.9 ppm. D: Metal fragments were detected at 1.9 ppm or more. [Explanation of symbols]

[0058] 1...ink pack, 2, 2'...magnet, 3...ink bottle, 10...irradiation unit, 11...nozzle surface, 12...irradiation surface, 20...inkjet head, 21...nozzle plate surface, 30...conveying section, 100...inkjet recording device, F...conveying direction, h1...distance, h2...distance, M...recording medium.

Claims

1. a contacting step of bringing the outer surface of the ink container having the ink-jet ink composition containing a pigment into contact with a magnet; a discharge step of discharging the inkjet ink composition from an inkjet head and depositing it on a recording medium, Inkjet recording method.

2. The inkjet ink composition is a radiation-curable type. The inkjet recording method according to claim 1 .

3. In the contact step, the value A calculated by the following formula is 5 [min cm ２ / mL] or more, [Equation 1] The inkjet recording method according to claim 1 .

4. In the contact step, the total contact area S between the magnet and the outer surface is 10 cm ２ That's all. The inkjet recording method according to claim 1 .

5. In the contacting step, the treatment time T during which the inkjet ink composition is exposed to the magnetic field generated by the magnet is 10 minutes or more. The inkjet recording method according to claim 1 .

6. The magnetic flux density of the magnet is 100 mT or more. The inkjet recording method according to claim 1 .

7. The volume average particle diameter (D50) of the pigment is 50 nm or more and 400 nm or less. The inkjet recording method according to claim 1 .

8. The pigment includes at least one pigment selected from the group consisting of cyan, magenta, yellow, black, and white. The inkjet recording method according to claim 1 .

9. an ink container having an inkjet ink composition containing a pigment; a magnet in contact with the outer surface of the ink container; an inkjet head that ejects the inkjet ink composition; Inkjet recording device.

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