Recording method and recording device

Abstract

This invention relates to a recording method and a recording apparatus, providing a recording method capable of suppressing pigment sedimentation in an ink chamber and color development differences in the recorded material. The recording method comprises: a supply step of supplying an ink composition from an ink chamber to an inkjet head; and an adhesion step of ejecting the ink composition from the inkjet head and adhering it to a recording medium, wherein the ink chamber receives the ink composition supplied from an ink receiving container with a volume of 40 mL or more, and the ink composition is an aqueous ink composition containing pigment and inorganic oxide particles with a specific gravity greater than that of the pigment.

Description

Technical Field

[0001] This invention relates to a recording method and a recording device. Background Technology

[0002] Inkjet recording methods can record high-definition images using relatively simple devices and have seen rapid development in various aspects. Among these developments, research has focused on aspects such as ejection stability. For example, Patent Document 1 discloses a recording method that, in order to improve the intermittent ejection stability of a recording device with a main and auxiliary inkjet chamber during long-term use, involves heating an ink composition containing a specified water-soluble organic solvent to a specified viscosity before ejection.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-001392

[0004] To prevent sudden printing interruptions when the ink in the ink reservoir runs out, it is considered to install an ink chamber between the ink reservoir and the inkjet head in the recording device. However, in such an ink chamber, pigments and other components in the ink composition may settle, and this pigment settling may affect the image quality of the recorded material. Summary of the Invention

[0005] The recording method of the present invention comprises: a supply step of supplying an ink composition from an ink chamber to an inkjet head; and an adhesion step of ejecting the ink composition from the inkjet head and adhering it to a recording medium, wherein the ink chamber receives the ink composition supplied from an ink receiving container with a capacity of 40 mL or more, and the ink composition is an aqueous ink composition containing pigments and inorganic oxide particles with a specific gravity greater than that of the pigments.

[0006] Furthermore, the recording apparatus of the present invention includes: an ink chamber; and an inkjet head, wherein an ink composition is supplied from the ink chamber to the inkjet head, the ink chamber receiving the ink composition supplied from an ink container, the ink chamber having a capacity of 40 mL or more, and the ink composition being an aqueous ink composition containing pigments and inorganic oxide particles with a specific gravity greater than that of the pigments. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the ink chamber, etc., of the recording apparatus used in the recording method of this embodiment.

[0008] Figure 2 This is a schematic cross-sectional view of a recording device that can be used in the recording method of this embodiment.

[0009] Explanation of reference numerals in the attached figures

[0010] 10: Ink chamber; 20: Inkjet head; 30: Ink container; 40: First ink flow path; 50: Second ink flow path. Detailed Implementation

[0011] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail with reference to the accompanying drawings. However, the present invention is not limited thereto, and various modifications can be made without departing from its spirit. It should be noted that in the drawings, the same elements are represented by the same symbols, and repeated descriptions are omitted. In addition, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the scale of the drawings is not limited to the scale shown in the drawings.

[0012] 1. Recording Method

[0013] The recording method of this embodiment includes: a supply step, in which an ink composition is supplied from an ink chamber to an inkjet head; and an adhesion step, in which the ink composition is ejected from the inkjet head and adhered to a recording medium, wherein the ink chamber receives the ink composition supplied from an ink receiving container, the capacity of which is 40 mL or more, and the ink composition is an aqueous ink composition containing pigments and inorganic oxide particles with a specific gravity greater than that of the pigments.

[0014] To prevent printing from being interrupted suddenly when the ink in the ink reservoir runs out, an ink chamber is installed in the recording device between the ink reservoir and the inkjet head.

[0015] In particular, such an ink chamber is useful in recording devices that perform mass printing, such as line printers.

[0016] In addition, when using pigments with excellent color rendering, pigment sedimentation can occur, which in turn affects the image quality of the recorded material.

[0017] However, it is known that in such an ink chamber, during the period when the recording device is not working, the pigments and other substances in the ink composition contained therein will settle, resulting in uneven concentration or color difference on the recorded material before and after the recording device stops working.

[0018] From the perspective of eliminating such sedimentation, one consideration is to agitate the ink chamber manually. However, the ink chamber is usually fixed between the ink container and the inkjet head in the recording device, making it difficult to stir up sediment simply by agitating the ink chamber. Alternatively, one could consider incorporating a stirring or circulation mechanism within the ink chamber to suppress pigment sedimentation. However, incorporating such mechanisms would complicate the device design and increase costs.

[0019] In this embodiment, as a method of recording using a recording device equipped with an ink chamber, by using an ink composition containing inorganic oxide particles with a specific gravity greater than that of the pigment, pigment sedimentation can be suppressed, thereby suppressing uneven concentration or color difference. The reason for this is presumably as follows: the inorganic oxide particles will first settle with the pigment, and the electrostatic repulsion of the settled inorganic oxide particles will suppress pigment sedimentation, but this is not particularly limited.

[0020] The structure of the recording method in this embodiment will now be described in detail.

[0021] 1.1. Supply Process

[0022] The supply process is the process of supplying the ink composition from the ink chamber to the inkjet head. Figure 1 A schematic diagram of a recording apparatus with an ink chamber as a secondary reservoir is shown. Figure 1 As shown, the recording apparatus 1 for implementing the recording method of this embodiment includes an ink chamber 10, an inkjet head 20, and a first ink flow path 40. The ink composition contained in the ink chamber 10 is supplied to the inkjet head 20 through the first ink flow path 40.

[0023] 1.1.1. Ink Chamber

[0024] The ink chamber 10 receives the ink composition supplied from the ink receiving container 30. The ink chamber 10 in this embodiment is not particularly limited, and can be, for example, an ink receiving chamber provided in a sub-tank or a continuous ink supply system (CISS).

[0025] The ink chamber 10 has a capacity of 40 mL or more, preferably 50 to 500 mL, more preferably 60 to 400 mL, and even more preferably 60 to 300 mL. Since the ink chamber 10 has a capacity of 40 mL or more, pigment sedimentation is easily generated; therefore, this invention is particularly useful.

[0026] The material of the ink chamber is not limited; metal, glass, resin, etc., can be used, as long as they can contain the ink composition.

[0027] 1.1.1.1. Secondary tank

[0028] The ink chamber 10, serving as a secondary ink tank, receives the ink composition supplied from the ink container 30, which serves as the main ink tank, and supplies the ink composition to the inkjet head 20 via the first ink flow path 40. The ink container 30 is not particularly limited and can be, for example, an ink cartridge, an ink bag, or any container that holds the ink composition. The capacity of the ink in the ink container 30 is not limited, but is preferably, for example, 100 to 3000 ml.

[0029] As the ink composition is consumed, the ink composition can be automatically supplied to the ink chamber 10, which serves as a secondary reservoir, under the control of the recording device. Alternatively, under the control of the recording device, ink composition can be supplied to the ink chamber 10, which serves as a secondary reservoir, and ink can be supplied from the ink chamber 10, which serves as a secondary reservoir, to the inkjet head 20 simultaneously. In this case, the recording method of this embodiment can also include a step of supplying ink composition from the ink container 30 to the ink chamber 10.

[0030] Regarding the location of the ink chamber 10, which serves as the secondary ink reservoir, it is not particularly limited as long as it is located between the inkjet head 20 and the ink container 30; for example, it can be located inside the inkjet head 20. Alternatively, the ink composition can be supplied from the upper vertical direction of the ink chamber 10. By supplying the ink composition from the top, the ink composition within the ink chamber 10 is agitated, thereby reducing the tendency for pigment sedimentation. Furthermore, the ink composition can be supplied to the inkjet head 20 from the lower vertical direction of the ink chamber 10. This reduces the likelihood of air bubbles being incorporated into the ink composition supplied to the inkjet head 20.

[0031] 1.1.1.2. Continuous Ink Supply System

[0032] A "continuous ink supply system" refers to a system in which ink composition is replenished into the ink chamber of a recording device, and recording is performed using the replenished ink composition. For example, the ink chamber 10 of a continuous ink supply system has an ink inlet to receive ink composition supplied from an ink container 30. The supplied ink composition is then supplied to the inkjet head 2 via a first ink flow path 40. The ink container 30 is not particularly limited; examples include ink bottles that are connected to the ink chamber 10 only when supplying ink composition to it. The connection is not limited to connections via connecting components; it can also be a connection where ink composition is supplied directly from the ink bottle to the ink inlet without using connecting components.

[0033] The ink composition can be manually supplied from the ink injection port to the ink chamber 10 of the continuous ink supply system. Alternatively, as the ink composition is consumed, ink can be automatically supplied from the ink chamber 10 to the inkjet head 20 under the control of the recording device. It should be noted that, since the continuous ink supply system uses the ink composition replenished in the ink chamber for recording, the operations of supplying the ink composition to the ink chamber 10 and supplying ink from the ink chamber 10 to the inkjet head 20 can be performed at different times.

[0034] 1.1.2. Inkjet Head

[0035] The inkjet head 20 is not particularly limited, and examples include: a line head that records in a line mode and a serial head that records in a serial mode.

[0036] In a line print method using a line print head, for example, a liquid jet head with a width greater than or equal to the recording width of the recording medium is fixed to an inkjet device. Then, the recording medium is moved along the scanning direction (the longitudinal direction of the recording medium, the transport direction), and ink droplets are ejected from the nozzles of the liquid jet head in conjunction with this movement. By performing this scanning, an image is recorded on the recording medium.

[0037] Alternatively, the recording medium can be fixed to the recording device. Then, an inkjet head, with a width exceeding the recording width of the recording medium, is moved along the scanning direction. In this movement, ink droplets are ejected from the nozzles of the inkjet head, and an image is recorded on the recording medium by performing this scanning. The scanning direction is the direction in which the scanning is performed.

[0038] Figure 2 A schematic cross-sectional view of a recording apparatus that can be used in the recording method of the present invention is shown. The inkjet head 20 is a line head with a width exceeding the recording width of the recording medium, for ejecting an ink composition and adhering it to the recording medium M. The inkjet head 20 has a nozzle array (not shown) on a nozzle surface 11 opposite to the recording medium M, which is an array of nozzles arranged along the recording width direction D2 of the recording medium. The recording medium M is supported by a belt B and conveyed along the conveying direction D1. The inkjet head 20 is not limited to two; one or more is acceptable. The belt B moves along the conveying direction D1 via a belt roller 60. Figure 1 The ink chamber and other components mentioned above are not shown in the figure. The recording device may also include a paper feed tray and a paper output tray, which are not shown in the figure.

[0039] In a serial method using a serial head, for example, a liquid jet head is mounted on a carriage that can move along the width of the recording medium. Then, the carriage is moved along the main scanning direction (the lateral and width direction of the recording medium), and ink droplets are ejected from the nozzle opening of the head in conjunction with this movement, thereby enabling the recording of an image on the recording medium.

[0040] Preferably, an inkjet head with a width greater than or equal to the recording width of the recording medium is used for recording via a line recording method. Line recording is suitable for high-speed and high-volume printing; however, because ink depletion is prone to occur, an ink chamber is preferred. Therefore, this invention is particularly useful in eliminating pigment settling in the ink chamber and the resulting color difference.

[0041] 1.1.3. Ink Flow Path

[0042] The ink flow path refers to the flow path in a recording device for the flow of ink. Examples of ink flow paths include: a first ink supply path 40 for supplying ink composition from the ink chamber 10 storing the ink composition to the ink head 20; a second ink supply path 50 for supplying ink composition from the ink container 30 to the ink chamber 10; and a flow path for allowing the ink composition to flow into the nozzle opening within the ink head 20.

[0043] The distance of the first ink supply path 40 from the ink chamber 10 to the inkjet head 20 is preferably 100 mm or more, or preferably 1500 mm or less. More preferably, it is 200 to 1500 mm, more preferably 300 to 1000 mm, and even more preferably 400 to 750 mm. By keeping the distance of the first ink supply path 40 within the above range, the ink composition tends to be easily re-stirred after settling during its passage through the first ink supply path 40. "To the inkjet head 20" refers to the nozzle of the inkjet head 20.

[0044] 1.2. Attachment process

[0045] The adhesion process is the process of ejecting an ink composition from an inkjet head and attaching it to a recording medium.

[0046] Examples of methods for ejecting an ink composition from a nozzle in an inkjet head include: driving a pressure generating device to eject the composition filled in the pressure generating chamber of the inkjet head from the nozzle, and using heat energy to eject the composition. Such ejection methods are also called inkjet printing. The method of applying pressure to the ink composition within the nozzle is not particularly limited; examples include piezoelectric methods that use piezoelectric elements to eject droplets of the ink composition, and heating methods that eject droplets by heating.

[0047] 1.3. Ink Composition

[0048] The ink composition is an aqueous ink composition containing pigments and inorganic oxide particles with a specific gravity greater than that of the pigments. In addition to the above, the ink composition may further include, as needed, water, water-soluble organic solvents, lactam compounds, resin emulsions, surfactants, pH adjusters, etc.

[0049] 1.3.1. Pigments

[0050] As pigments, there are no particular restrictions, and the following can be used: azo pigments (e.g., including azo lakes, insoluble azo pigments, condensed azo pigments, chelated azo pigments, etc.), polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, pyrene pigments, anthraquinone pigments, quinacrine pigments, dioxazine pigments, thioindole pigments, isoindole ketone pigments, quinophthalone pigments, etc.), nitro pigments, nitroso pigments, aniline black, and other organic pigments; carbon black (e.g., furnace black, thermal decomposition lamp black, acetylene black, channel black, etc.), metal oxides, metal sulfides, metal salts, and other inorganic pigments; calcium carbonate, talc, and other extender pigments, etc. A single pigment can be used, or two or more can be used in combination.

[0051] The pigment preferably includes any one of carbon black and organic pigments. This results in a lighter specific gravity, which further inhibits pigment sedimentation.

[0052] The specific gravity of the pigment is preferably 0.1 to 2.0, more preferably 0.1 to 1.9, more preferably 0.2 to 1.8, and most preferably 0.3 to 1.7. By keeping the specific gravity of the pigment within the above range, there is a tendency to further suppress pigment sedimentation.

[0053] The pigments described above can be prepared into pigment dispersions obtained by dispersing them in water using a dispersant. Examples include dispersions using a resin as a dispersant (hereinafter also referred to as "resin-dispersed pigments").

[0054] Alternatively, one could cite the example of a dispersion obtained by dispersing a self-dispersible surface-treated pigment (hereinafter also referred to as "self-dispersible pigment") in water, wherein the self-dispersible surface-treated pigment has hydrophilic groups introduced onto the surface of the pigment particles through a chemical reaction.

[0055] Alternatively, one could cite the example of a dispersion obtained by dispersing a polymer-coated pigment in water.

[0056] The preferred component is a self-dispersible pigment. By using a self-dispersible pigment, the water repellency of the nozzle plate and the stability of intermittent printing are further improved.

[0057] The pigments and dispersants constituting the above-mentioned pigment dispersions can be used individually or in combination of two or more.

[0058] The volume average particle size of the pigment is preferably 20-250 nm, more preferably 40-230 nm, even more preferably 60-210 nm, particularly preferably 80-190 nm, and even more preferably 100-180 nm.

[0059] By making the volume average particle size of the pigment 20 nm or more, there is a tendency to further improve the color rendering. In addition, by making the volume average particle size of the pigment 250 nm or less, there is a tendency to further suppress pigment sedimentation.

[0060] The pigment content, based on solid components, is preferably 0.5% by mass or more relative to the total amount of the ink composition. More preferably, it is 1.0 to 10% by mass, more preferably 3.0 to 10% by mass, and even more preferably 4.0 to 8.0% by mass. By keeping the pigment content within the above range, sedimentation is suppressed, and color development is further improved.

[0061] 1.3.2. Inorganic oxide particles

[0062] Inorganic oxide particles only need to have a specific gravity greater than that of the pigment; there are no particular restrictions. Inorganic oxide particles can inhibit pigment sedimentation. In addition, they can also inhibit ink penetration into the recording medium, resulting in excellent color development of the recorded material.

[0063] The specific gravity of the inorganic oxide particles is preferably 2.0 to 6.0, more preferably 2.0 to 5.0, and most preferably 2.0 to 4.0. By keeping the true specific gravity of the inorganic oxide particles within the above range, there is a tendency to further suppress pigment sedimentation.

[0064] The specific gravity of the inorganic oxide particles is preferably 0.1 or greater than that of the pigment. Furthermore, it is preferably 0.2 to 3.0, more preferably 0.3 to 2.0, and even more preferably 0.3 to 1.0.

[0065] The inorganic oxide particles are not particularly limited, and examples include: silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, cerium oxide, antimony oxide, tin oxide, tantalum oxide, zinc oxide, lead oxide, and indium oxide. Preferably, they include at least one selected from the group consisting of silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, and cerium oxide. By using such inorganic oxide particles, curling of the obtained record is further suppressed, thereby further improving shelf life. It should be noted that one type of inorganic oxide particle can be used alone, or two or more can be used in combination. The inorganic oxide particles only need to be particles that contain at least an inorganic oxide. Particles composed of inorganic oxides are preferred.

[0066] Inorganic oxide particles can be surface-treated. For example, silica can be surface-treated with alumina. This expands the range of pH values ​​at which silica can be stably dispersed and further improves its dispersion stability.

[0067] Commercially available silica, as described above, can also be used, such as: CATALOID series SI-45P, SI-80, SI-30P, and S-40 manufactured by Nichibukai Chemical Co., Ltd., and SNOWTEX 20, SNOWTEX 30P, SNOWTEX 40, SNOWTEX O, SNOWTEX N, and SNOWTEX C manufactured by Nissan Chemical Industries, Ltd. Among the silicas described above, from the viewpoint of further effectively and reliably achieving the effects of the present invention, SI-45P and / or SI-80 are preferred.

[0068] The volume average particle size of the inorganic oxide particles is preferably 100 nm or less, or preferably 5 nm or more. More preferably, it is 10 to 95 nm, even more preferably 20 to 90 nm, and still more preferably 40 to 80 nm. By making the average particle size of the inorganic oxide particles 100 nm or less, in addition to suppressing the whitening of the obtained recording, there is a tendency to further suppress pigment precipitation. Furthermore, by making the average particle size of the inorganic oxide particles in the above range or above, there is a tendency to further improve the color development.

[0069] The average particle size of inorganic oxide particles can be determined using a particle size distribution analyzer based on the dynamic light scattering method. An example of such an analyzer is the "Zeta Potential-Particle Size-Molecular Weight Measurement System ELSZ2000ZS" (trade name) manufactured by Otsuka Electronics Co., Ltd., which uses a zero-difference optical system for frequency analysis. It should be noted that, unless otherwise specified, "average particle size" in this specification refers to the average particle size (D50) of a number of standards.

[0070] The content of inorganic oxide particles, based on the solid components, is preferably 0.5 to 8.0% by mass relative to the total amount of the ink composition, more preferably 1.0 to 6.0% by mass, and even more preferably 1.5 to 4.5% by mass. By keeping the content of inorganic oxide particles within the above range, there is a tendency to further suppress sedimentation and further improve color development.

[0071] 1.3.3. Water

[0072] The ink composition of this embodiment is a water-based ink. Water-based inks are inks containing water as the main solvent component. The water content in the water-based ink relative to the total amount of the ink composition is preferably 40% by mass or more, more preferably 40 to 98% by mass, further preferably 45% by mass or more and 80% by mass or less, more preferably 50% by mass or more and 75% by mass or less, and even more preferably 55% by mass or more and 70% by mass or less.

[0073] 1.3.4. Water-soluble organic solvents

[0074] The ink composition of this embodiment preferably contains a water-soluble organic solvent. By including a water-soluble organic solvent in the ink composition, there is a tendency to further improve its shelf life.

[0075] Water-soluble organic solvents are not particularly limited, but can be listed as follows: polyols of three or more such as glycerol; nitrogen-containing solvents such as 2-pyrrolidone and N-methylpyrrolidone; diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, propylene glycol, butanediol, pentanediol, and 1,2-hexanediol; and diol monoalkyl ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, and triethylene glycol monobutyl ether.

[0076] The content of water-soluble organic solvent relative to the total amount of the ink composition is preferably 5.0 to 25% by mass, more preferably 7.5 to 20% by mass, and even more preferably 10 to 15% by mass. By keeping the content of water-soluble organic solvent within the above range, there is a tendency to further suppress pigment sedimentation and further improve printing durability.

[0077] 1.3.5. Lactam compounds

[0078] The ink composition of this embodiment may also contain lactam compounds. By containing lactam compounds, there is a tendency to further improve the resolubility even when inorganic oxide particles agglomerate, and to further improve the printability.

[0079] Lactam compounds are preferably water-soluble. Water-soluble lactam compounds that are liquid at room temperature are also those that use the aforementioned water-soluble organic solvents.

[0080] Lactam compounds have 3 or more membered rings, preferably 3 to 9 membered rings, and more preferably 5 to 8 membered rings.

[0081] Lactam compounds are not particularly limited, and examples include: 2-pyrrolidone, N-methyl-2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, 3-methoxy-2-pyrrolidone, 3-acetoxy-2-pyrrolidone, 4-pentanolactam, ε-caprolidone, etc.

[0082] The content of the lactam compound relative to the total amount of the ink composition is preferably 1.0 to 10% by mass, more preferably 1.5 to 8.0% by mass, and even more preferably 2.0 to 6.0% by mass. By keeping the content of the lactam compound within the above range, there is a tendency to further improve the printability.

[0083] 1.3.6. Resin Emulsion

[0084] It may further include a resin emulsion. The resin emulsion is not particularly limited, and examples include (meth)acrylic resin emulsions, urethane resin emulsions, etc. By using such a resin emulsion, there is a tendency to further suppress the bleeding of the resulting image and further improve its abrasion resistance. A single resin emulsion may be used, or two or more may be used in combination.

[0085] Acrylic resin emulsions are not particularly limited, and examples include substances polymerized from (meth)acrylic resins, (meth)acrylic resin esters, and other (meth)acrylic monomers, as well as substances copolymerized from (meth)acrylic monomers such as styrene acrylic resins with other monomers. Among these, anionic acrylic resin microparticles are preferred.

[0086] As long as the urethane resin emulsion is a resin emulsion containing urethane bonds in its molecule, it is not particularly limited, and examples include: polyether-type urethane resins with ether bonds in their main chain, polyester-type urethane resins with ester bonds in their main chain, and polycarbonate-type urethane resins with carbonate bonds in their main chain. Among these, anionic urethane resin microparticles are preferred.

[0087] The content of the resin emulsion, based on the solid components, relative to the total amount of the ink composition is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 3.0% by mass, and even more preferably 0.1 to 1.0% by mass. By keeping the content of the resin emulsion within the above range, there is a tendency to further improve the printability.

[0088] 1.3.7. Surfactants

[0089] The ink composition of this embodiment may contain a surfactant. The surfactant is not particularly limited, but examples include acetylene glycol surfactants, fluorinated surfactants, and organosilicon surfactants.

[0090] Acetylene glycol surfactants are not particularly limited, but are preferably selected from one or more of the alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyn-4,7-diol and 2,4,7,9-tetramethyl-5-decyn-4,7-diol, as well as alkylene oxide adducts of 2,4-dimethyl-5-decyn-4-ol and 2,4-dimethyl-5-decyn-4-ol. It should be noted that acetylene glycol surfactants can be used alone or in combination with two or more.

[0091] Fluorinated surfactants are not particularly limited, and examples include: perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkyl amine oxides. It should be noted that fluorinated surfactants can be used alone or in combination with two or more.

[0092] Examples of organosilicon surfactants include polysiloxane compounds and polyether-modified organosilicon compounds. It should be noted that organosilicon surfactants can be used alone or in combination of two or more.

[0093] The surfactant content relative to the total amount of the ink composition is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 2.0% by mass, and even more preferably 0.3 to 1.5% by mass. By keeping the surfactant content within the above range, there is a tendency to further improve printability.

[0094] 1.3.8. pH adjuster

[0095] pH adjusters are not particularly limited and can include, for example, inorganic acids (e.g., sulfuric acid, hydrochloric acid, nitric acid, etc.), inorganic bases (e.g., lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, etc.), organic bases (triethanolamine, diethanolamine, monoethanolamine, tripropanolamine), and organic acids (e.g., adipic acid, citric acid, succinic acid, etc.). Organic bases are preferred. A single pH adjuster can be used, or two or more can be used in combination.

[0096] The content of the pH adjuster relative to the total amount of the ink composition is preferably 0.1 to 2.0% by mass, more preferably 0.1 to 1.5% by mass, and even more preferably 0.1 to 1.0% by mass. By keeping the content of the pH adjuster within the above range, there is a tendency to further suppress precipitation and further improve printability.

[0097] 1.4 Recording Media

[0098] The recording medium is not particularly limited, and examples include absorbent recording media, low-absorbent recording media, and non-absorbent recording media. Among these, absorbent recording media and low-absorbent recording media are preferred, and absorbent recording media are more preferred. The higher the absorbency, the easier it is to exert the filling effect of inorganic oxide microparticles, thereby easily improving color development. Therefore, this invention is particularly useful.

[0099] Among them, "low-absorbency recording media" or "non-absorbent recording media" refers to media in which the water absorption rate is 10 mL / m³ from the start of contact to 30 msec in the Bristow process. 2 The following is the recording medium. The Brinell method is the most widely used method for determining liquid absorption over a short period of time, and it is also used by the Japan Pulp Technology Association (JAPAN TAPPI). For details of the test method, please refer to Specification No. 51 "Paper and Paperboard - Liquid Absorption Test Method - Brinell Method" in "JAPAN TAPPI Pulp Test Methods 2000 Edition".

[0100] It should be noted that low-absorbency recording media refers to media with a water absorption rate of 5 mL / m³. 2 Above and 10mL / m 2 The following are recording media. On the other hand, absorbent recording media refers to those with a water absorption capacity exceeding 10 mL / m. 2 The recording medium.

[0101] Absorbent recording media are not particularly limited, and examples include: ordinary paper such as electronic photograph paper with high ink composition permeability, inkjet paper (inkjet-specific paper with an ink-absorbing layer composed of silica particles or alumina particles or an ink-absorbing layer composed of hydrophilic polymers such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP)). Additionally, fabrics can also be listed.

[0102] As a low-absorbency recording medium, it is not particularly limited, and examples include coated paper with a coating layer on its surface for receiving oil-based inks. Coated paper is not particularly limited, and examples include printing base papers such as art paper, coated paper, and matte paper.

[0103] Non-absorbent recording media are not particularly limited and can be exemplified by: plastic films and sheets such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, and polyurethane; metal sheets such as iron, silver, copper, and aluminum; or metal sheets and plastic films made by vapor deposition of the above metals, as well as alloy sheets such as stainless steel and brass; and recording media with plastic films such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, and polyurethane bonded (coated) to paper substrates.

[0104] 2. Recording device

[0105] The recording apparatus of this embodiment includes: an ink chamber; and an inkjet head, wherein an ink composition is supplied from the ink chamber to the inkjet head, the ink chamber receives the ink composition supplied from an ink container, the ink chamber has a capacity of 40 mL or more, and the ink composition is an aqueous ink composition containing pigments and inorganic oxide particles with a specific gravity greater than that of the pigments.

[0106] Example

[0107] The present invention will now be described in more detail using examples and comparative examples. The present invention is not limited to the examples described below.

[0108] 1. Ink Preparation

[0109] The components were loaded into a mixing tank and mixed to form the compositions described in Tables 1-3. The mixture was then filtered through a 5μm membrane filter to obtain the inkjet inks of each example. It should be noted that, unless otherwise specified, the values ​​for each component shown in the examples in the tables represent mass percent. Additionally, the values ​​for inorganic oxide particles, pigment dispersions, and resins in the tables represent the mass percent of the solid components.

[0110] Table 1

[0111]

[0112] Table 2

[0113]

[0114] Table 3

[0115]

[0116] The abbreviations and product ingredients used in Tables 1-3 are as follows.

[0117] Pigment dispersion

[0118] Black pigment A (average particle size 130nm, carbon black)

[0119] Black pigment B (average particle size 180nm, carbon black)

[0120] Black pigment C (average particle size 80nm, carbon black)

[0121] Black pigment D (average particle size 250nm, carbon black)

[0122] Black pigment E (average particle size 60nm, carbon black)

[0123] Cyan pigment (average particle size 130nm, pigment blue 15:3)

[0124] Magenta pigment (average particle size 130nm, Pigment Violet 19)

[0125] Yellow pigment (average particle size 130nm, Pigment Yellow 74)

[0126] White pigment (titanium oxide, carbon black, average particle size 250nm, manufactured by Ishihara Sangyo Co., Ltd., R-550)

[0127] Inorganic oxide particles

[0128] Colloidal silica (average particle size 45nm, manufactured by Nichibukai Chemical Co., Ltd., SI-45P)

[0129] Colloidal silica (average particle size 25nm, SI-50 manufactured by Nichibukai Chemical Co., Ltd.)

[0130] Colloidal silica (average particle size 80nm, manufactured by Nichibukai Chemical Co., Ltd., SI-80P)

[0131] Alumina (average particle size 40nm, BYK NANOBYK-3600)

[0132] Water-soluble organic solvents

[0133] glycerin

[0134] Triethylene glycol

[0135] Triethylene glycol monobutyl ether

[0136] Triethylene glycol monomethyl ether

[0137] 1,2-Hexanediol

[0138] lactam compounds

[0139] 1-(2-hydroxyethyl)-2-pyrrolidone

[0140] ε-caprolactam

[0141] resin emulsion

[0142] Styrene-acrylic resin emulsion (manufactured by Starlight PMC, X-436, Tg: 33℃, acid value 33mgKOH / g)

[0143] surfactants

[0144] OLFINE E1010 (trade name manufactured by Air Products, an acetylene glycol surfactant).

[0145] SURFYNOL 104 (trade name manufactured by Nissin Chemical Industry Co., Ltd., an acetylene glycol surfactant)

[0146] OLFINE EXP4300 (trade name manufactured by Air Products, an acetylene glycol surfactant).

[0147] pH adjuster

[0148] Triethanolamine

[0149] 1.1. Examples of preparation of pigment dispersions of black pigments A to E

[0150] Carbon black pigment master particles are mixed with water and then pulverized using a bead mill to prepare a pigment dispersion. The average particle size of the resulting particles is adjusted to the aforementioned particle sizes by varying the stirring time. Next, the pulverized particles undergo surface treatment to introduce hydrophilic groups onto the particle surface. This yields self-dispersible black pigment dispersions A through E.

[0151] The surface treatment is performed as follows.

[0152] 20.0 g of pigment, 11.0 mmol of ((4-aminobenzoylamino)-methane-1,1-diyl)bisphosphonate monosodium salt, 20.0 mmol of nitric acid, and 200 mL of pure water were mixed. Carbon black (trade name "Black Pearl 880", manufactured by Cabot) was used as the pigment. The mixture was then mixed at 6,000 rpm at room temperature using a Silverson mixer. After 30 minutes, 20.0 mmol of sodium nitrite dissolved in a small amount of water was slowly added to the mixture. The temperature of the mixture was raised to 60°C by adding sodium nitrite. The reaction was carried out at this condition for 1 hour. After washing with water, the pH of the mixture was adjusted to 10 using an aqueous sodium hydroxide solution. The resulting pigment is a self-dispersible pigment with -C6H4-CONH-CH-(PO(OH)(ONa))(PO(OH)2) groups bonded to the surface of the pigment particles.

[0153] 1.2. Example of preparation of pigment dispersion of colored pigments

[0154] The pigment master particles of the aforementioned cyan pigment were mixed with water, and the pigment master particles were stirred and pulverized using a bead mill to prepare a pigment dispersion. At this time, the average particle size of the resulting particles was adjusted to the aforementioned particle size by changing the stirring time.

[0155] 20.0 g of the pigment, 3.5 mmol of ((4-aminobenzoylamino)-methane-1,1-diyl)bisphosphonate monosodium salt, 10.0 mmol of nitric acid, and 200 mL of pure water were mixed. The mixture was then stirred at 6,000 rpm at room temperature using a Silverson mixer. After 30 minutes, 10.0 mmol of sodium nitrite dissolved in a small amount of water was slowly added to the mixture. The temperature of the mixture was raised to 60°C by adding sodium nitrite. The reaction was carried out at this temperature for 1 hour. The mixture was then washed with water, and the pH was adjusted to 10 using an aqueous sodium hydroxide solution. A self-dispersible pigment with -C6H4-CONH-CH-(PO(OH)(ONa))(PO(OH)2) groups bonded to the surface of the pigment particles was obtained.

[0156] The above yields a self-dispersible cyan pigment dispersion.

[0157] In addition to changing the pigment to the aforementioned substance, pigment dispersions of magenta and yellow pigments can also be obtained.

[0158] 1.3. Example of preparation of pigment dispersion of white pigment

[0159] Using the aforementioned titanium dioxide particles as pigment master particles, a pigment dispersion was prepared by mixing a dispersant (DISPERBYK-190, manufactured by BYK Chemical Company) with water at a mass ratio of pigment:dispersant = 3:1 and stirring.

[0160] It should be noted that the specific gravity of carbon black is 1.9, the specific gravity of colored pigments is 1.4~1.6, the specific gravity of titanium dioxide is 4.2, the specific gravity of silicon dioxide is 2.2, and the specific gravity of aluminum oxide is 4.0.

[0161] 2. Evaluation

[0162] Modify the LX10000F (manufactured by Seiko Epson) to create a line printer with auxiliary ink reservoirs of the various capacities listed in Tables 1-3, and fill it with the inks listed in Tables 1-3 in an ejector manner. It should be noted that this allows ink to be supplied from the ink cartridge to the auxiliary ink reservoir. Furthermore, it also allows ink to be supplied from the auxiliary ink reservoir to the printhead. The printhead is used as follows... Figure 2 The image shows a line printhead. The nozzle density in the width direction is set to 600 npi. The distance of the ink supply path from the sub-slot to the nozzle of the printhead is used as the path length in the table. In the example without a sub-slot, the distance from the ink cartridge to the nozzle of the printhead is used.

[0163] In the example with a stirring mechanism and an ink circulation mechanism, a screw is installed in the sub-tank. An ink return path is provided between the inkjet head and the sub-tank, allowing the ink to circulate between them. Thus, during the settling test described later, the ink in the sub-tank is stirred by the screw, causing the ink to circulate between the inkjet head and the sub-tank.

[0164] Furthermore, solid patterns were recorded on plain paper (Xerox P paper) under the conditions of ink adhesion amount of 6 ng / dot and recording resolution of 600×600 dpi.

[0165] 2.1 Settlement Test

[0166] The ink cartridges were left to stand for two weeks with the secondary ink tank filled. After standing, solid patterns were printed under the above conditions until all the ink in the secondary ink tank was used up, and continuous printing was carried out. Color measurements were taken on the solid patterns recorded before standing and on each sheet of paper recorded during continuous printing to obtain the maximum color difference between each solid pattern. Based on the obtained color difference, the sedimentation was evaluated according to the following evaluation criteria. In the example without a secondary ink tank, printing continued until the ink in the ink cartridge was used up.

[0167] It should be noted that during color measurement, a Spectrolino colorimeter manufactured by GretagMacbeth was used to measure the values ​​of L*a*b* as specified in CIELAB, and the difference (ΔE) between these values ​​was used as the color difference.

[0168] Evaluation criteria

[0169] A: The maximum color difference between each solid pattern is less than 1.0;

[0170] B: The maximum color difference between each solid pattern is greater than 1.0 and less than 2.0;

[0171] C: The maximum color difference between each solid pattern is greater than 2.0 and less than 2.5;

[0172] D: The maximum color difference between each solid pattern is 2.5 or more.

[0173] 2.2. Color Developing Properties

[0174] The OD value of the solid pattern printed before placement was measured using a reflectance densitometer (trade name: Spectrolino, manufactured by Gretag). Based on the obtained OD value, color rendering was evaluated using the following criteria.

[0175] Evaluation criteria

[0176] A: OD value is 1.33 or higher;

[0177] B: OD value is above 1.25 and below 1.33;

[0178] C: OD value above 1.20 and below 1.25;

[0179] D: OD value is below 1.20.

[0180] 2.3. Printability

[0181] Fill the sub-slot with ink, ensuring no ink is supplied from the cartridge to the sub-slot, and evaluate how much printing can be performed using the ink remaining in the sub-slot. It should be noted that the evaluation involves printing a monochrome pattern as specified in ISO / IEC 19752. Count the number of sheets printed until the ink in the sub-slot is exhausted, and evaluate printability using the following criteria. In the example without a sub-slot, there is no cartridge, and printing is impossible; therefore, it is evaluated as unprintable.

[0182] Evaluation criteria

[0183] A: Can print more than 10,000 copies;

[0184] B: Can print more than 6,000 but less than 10,000 copies;

[0185] C: Fewer than 6,000 sheets can be printed;

[0186] D: Cannot be printed.

[0187] 3. Evaluation Results

[0188] As can be seen from the comparison between the examples and the comparative examples, by using an ink composition containing inorganic oxide particles with a specific gravity greater than that of the pigment, pigment sedimentation can be suppressed and color development can be improved even in a recording device with a sub-groove.

[0189] In Comparative Examples 1, 4, and 5, the inks do not contain inorganic oxide particles, or do not contain inorganic oxide particles with a specific gravity greater than that of the pigment, resulting in poor pigment sedimentation inhibition.

[0190] In Comparative Examples 4 and 5, the recording device does not have a secondary tank, or does not have a secondary tank with a capacity of 40 ml or more. Therefore, although the pigment sedimentation suppression is excellent, the printing continuity is poor.

[0191] In Comparative Example 6, the ink did not contain inorganic oxide particles; therefore, it could not prevent the ink from penetrating the recording medium. Furthermore, a pigment with low color development was used, resulting in poor color development. It should be noted that using pigments with low color development reduces the likelihood of pigment sedimentation.

[0192] It should be noted that, instead of a line printer with a secondary slot, the secondary slot can be replaced with a CISS slot of the same capacity, and the data can be recorded. The results will be similar to those obtained with a secondary slot.

Claims

1. A recording method using a recording device, characterized in that, The recording method has the following features: In the first supply process, an ink composition is supplied from the ink chamber to the ink head via a first ink flow path; The second supply process involves supplying an ink composition from an ink receiving container to the ink chamber via a second ink flow path; as well as The adhesion process involves ejecting the ink composition from the inkjet head and adhering it to the recording medium. The ink chamber receives the ink composition supplied from the ink containing container, and the ink chamber has a capacity of 40 mL or more and 500 mL or less. The ink composition is a water-based ink composition containing pigments and inorganic oxide particles with a specific gravity greater than the pigments. The recording device includes the ink chamber, the ink receiving container, the inkjet head, the first ink flow path, and the second ink flow path. The ink chamber is a secondary tank. The ink container is an ink cartridge or an ink bag.

2. The recording method according to claim 1, characterized in that, The pigment has a volume average particle size of 20~250nm.

3. The recording method according to claim 1, characterized in that, The content of the inorganic oxide particles is 0.5 to 8.0% by mass relative to the total amount of the ink composition.

4. The recording method according to claim 1, characterized in that, The volume average particle size of the inorganic oxide particles is less than 100 nm.

5. The recording method according to claim 1, characterized in that, The ink composition contains a water-soluble organic solvent. The content of the water-soluble organic solvent is 5.0 to 25% by mass relative to the total amount of the ink composition.

6. The recording method according to claim 1, characterized in that, The distance of the ink flow path from the ink chamber to the inkjet head is 50~1500mm.

7. The recording method according to claim 1, characterized in that, The pigment includes any of carbon black and organic pigments.

8. The recording method according to claim 1, characterized in that, The inorganic oxide particles comprise one or more of the group consisting of silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, and cerium oxide.

9. The recording method according to claim 1, characterized in that, The ink composition contains a lactam compound.

10. The recording method according to claim 1, characterized in that, The content of the pigment is 1.0 to 10% by mass relative to the total amount of the ink composition.

11. The recording method according to claim 1, characterized in that, In the attachment process, the inkjet head is used to record data using a line recording method, and the inkjet head has a width greater than or equal to the width of the recording medium.

12. The recording method according to any one of claims 1 to 11, characterized in that, The recording medium is an absorbent recording medium.

13. A recording apparatus characterized by comprising: Used in the recording method of claim 1, The recording apparatus includes: the ink chamber, the inkjet head, the ink receiving container, the ink composition, the first ink flow path, and the second ink flow path.

Images