Image forming device

Abstract

To provide an image forming device that can achieve an appropriate beading quality and obtain appropriate discharge characteristics, while forming an image at high speed using a high-density nozzle.SOLUTION: An image forming device comprises a nozzle plate which has at least two nozzle holes and a piezoelectric element, and ink including an alcohol-system organic solvent whose boiling point is 250°C or less, where the number of the nozzle holes on a surface of the nozzle plate is averagely 10 / mm2 or more and a distance between the nozzle holes formed adjacently in a nearly vertical direction with respect to a conveying direction of a recording medium is 150 μm or more and 500 μm or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] In recent years, there has been an increasing demand for printers with high productivity, and printer speeds have been increased by mounting many inkjet heads to obtain the necessary resolution.

[0003] However, there is a concern that installing many inkjet heads will increase the size of the printer, so by arranging the nozzle holes at a high density, it is possible to achieve both a smaller printer and faster speeds. Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional technology has a problem in that beading occurs when forming an image at high speed with high-density nozzles. Furthermore, there is a problem in that the ink does not wet the inside of the head liquid chamber sufficiently, making it difficult to obtain sufficient initial filling properties and ejection stability.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus which can form an image at high speed with high density nozzles, while achieving good beading quality and good ejection characteristics. [Means for solving the problem]

[0006] An image forming apparatus according to an embodiment of the present invention comprises: a nozzle plate having at least two nozzle holes and a piezoelectric element; and an ink containing an alcohol-based organic solvent having a boiling point of 250° C. or less; The number of the nozzle holes on the surface of the nozzle plate is 10 / mm on average. 2 That's all. In the image forming apparatus, the distance between adjacent nozzle holes in a direction substantially perpendicular to the transport direction of the recording medium is 150 μm or more and 500 μm or less. Effect of the Invention

[0007] According to the present invention, it is possible to provide an image forming apparatus which can form an image at high speed using high density nozzles, while achieving good beading quality and good ejection characteristics. [Brief description of the drawings]

[0008] [Figure 1] FIG. 4 is an explanatory diagram showing an example of a positional relationship of nozzle holes in a nozzle according to an embodiment of the present invention. [Diagram 2] 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a perspective view of a main tank in the image forming apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Image forming device) An image forming apparatus according to one embodiment of the present invention has a nozzle plate having at least two nozzle holes and a piezoelectric element, and ink containing an alcohol-based organic solvent having a boiling point of 250°C or less, and other components as necessary.

[0010] <Nozzle plate> The nozzle plate has a nozzle hole and a piezoelectric element. An image forming apparatus according to one embodiment of the present invention is capable of ejecting ink from nozzle holes formed on the surface of the nozzle plate by vibrating the piezoelectric elements formed on the nozzle plate.

[0011] At least two of the nozzle holes are formed on the surface of the nozzle plate (hereinafter sometimes referred to as the "ink ejection surface"), and the distance between adjacent nozzle holes in a direction approximately perpendicular to the transport direction of the recording medium is 150 μm or more and 500 μm or less. Fig. 1 is an explanatory diagram showing an example of the positional relationship of nozzle holes in a nozzle according to one embodiment of the present invention. As shown in Fig. 1, a nozzle 10 has a plurality of nozzle holes (11 and 12 in Fig. 1, etc.). Here, the direction substantially perpendicular to the transport direction of the recording medium may be a completely perpendicular direction Y to the transport direction X of the recording medium shown in Fig. 1, or the nozzle holes may be adjacent to each other in a diagonal direction of the perpendicular direction Y, such as nozzle hole 11 and nozzle hole 12.

[0012] Hereinafter, the inks contained in the image forming apparatus according to one embodiment of the present invention will be described. The ink contains an organic solvent, and may further contain water, a coloring material, a resin, an additive, and the like, as necessary.

[0013] <Organic solvent> In one embodiment of the present invention, an alcohol-based organic solvent having a boiling point of 250° C. or less at 1 atmospheric pressure is used as the organic solvent. The alcohol-based organic solvent is not particularly limited and may be appropriately selected depending on the purpose. Examples of the alcohol-based organic solvent include polyhydric alcohols, and ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers. Specific examples of the alcohol-based organic solvent are not particularly limited and can be appropriately selected depending on the purpose. Examples of the alcohol-based organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, and glycerin. polyhydric alcohols such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether. Among these, glycol ethers having a temperature of 180° C. or less are preferred because they not only function as a wetting agent and a compatibilizer but also provide good drying properties.

[0014] Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also suitably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol. Specific examples of the glycol ether compound include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0015] Polyol compounds having 8 or more carbon atoms and glycol ether compounds can improve the permeability of ink when paper is used as the recording medium.

[0016] The content of the organic solvent in the ink is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of the drying property and ejection reliability of the ink, it is preferably 5% by mass to 60% by mass, more preferably 20% by mass to 60% by mass. When the organic solvent is a glycol ether compound, the content of the glycol ether compound in the ink is preferably 5% by mass to 10% by mass.

[0017] The boiling point of the alcohol-based organic solvent is not more than 250° C., and preferably not more than 180° C. When the boiling point is not more than 250° C., the occurrence of beading can be prevented when a high-density nozzle head is used.

[0018] <Water> The water content in the ink is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of the drying property and ejection reliability of the ink, however, it is preferably from 10% to 90% by mass, and more preferably from 20% to 60% by mass.

[0019] <Coloring material> The coloring material is not particularly limited and can be appropriately selected depending on the purpose. Examples of the coloring material include pigments and dyes. The pigment may be an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more. Mixed crystals may also be used. Examples of the pigment that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments. As inorganic pigments, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used. As organic pigments, azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be used. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used. Specific examples of pigments for black colors include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (CI Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (CI Pigment Black 1). In addition, for color, CI Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, CI Pigment Yellow Range 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88 , 101 (red oxide), 104, 105, 106, 108 (cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, CI Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38; CI Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. One type of dye may be used alone, or two or more types may be used in combination.

[0020] Examples of the dyes include CI Acid Yellow 17, 23, 42, 44, 79, 142, CI Acid Red 52, 80, 82, 249, 254, 289, CI Acid Blue 9, 45, 249, CI Acid Black 1, 2, 24, 94, CI Food Black 1, 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Directed Black 19, 38, 51, 71, 154, 168, 171, 195, and CI Reactive Red. 14, 32, 55, 79, 249, and CI Reactive Black 3, 4, and 35.

[0021] The content of the coloring material in the ink is preferably from 0.1% to 15% by mass, and more preferably from 1% to 10% by mass, from the viewpoints of improving image density, good fixing property and ejection stability.

[0022] Methods for dispersing a pigment to obtain an ink include a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant. As a method for introducing a hydrophilic functional group into a pigment to make it a self-dispersing pigment, for example, a method in which a functional group such as a sulfone group or a carboxyl group is added to a pigment (e.g., carbon) to make it dispersible in water can be mentioned. As a method for dispersing a pigment by coating its surface with a resin, there is a method in which the pigment is encapsulated in a microcapsule to make it dispersible in water. This can be called a resin-coated pigment. In this case, it is not necessary for all of the pigments blended in the ink to be coated with a resin, and uncoated or partially coated pigments may be dispersed in the ink as long as the effect of the present invention is not impaired. Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a known polymeric dispersant, such as a surfactant. As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the pigment. RT-100 (nonionic surfactant) manufactured by Takemoto Oil Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as the dispersant. The dispersant may be used alone or in combination of two or more kinds.

[0023] <Pigment dispersion> It is possible to obtain ink by mixing a pigment with materials such as water or an organic solvent, or it is also possible to manufacture ink by mixing a pigment with other materials such as water and a dispersant to prepare a pigment dispersion, and then mixing the resulting mixture with materials such as water or an organic solvent. The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as required, and adjusting the particle size. Dispersion is preferably performed using a dispersing machine. The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency in terms of the maximum number is preferably 20 nm or more and 500 nm or less, more preferably 20 nm or more and 150 nm or less, in order to improve the dispersion stability of the pigment and the image quality such as ejection stability and image density. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.). The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of obtaining good ejection stability and increasing image density, the content is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 0.1% by mass or more and 30% by mass or less. It is preferable that the pigment dispersion is degassed, if necessary, by filtering coarse particles using a filter, a centrifugal separator, or the like.

[0024] <Resin> The type of resin contained in the ink is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic styrene resin, and acrylic silicone resin. Resin particles made of these resins may also be used. The ink can be obtained by mixing the resin particles in a resin emulsion state in which the resin particles are dispersed using water as a dispersion medium with materials such as coloring materials and organic solvents. The resin may be a synthetic resin or a commercially available resin, and may be used alone or in combination of two or more kinds of resin particles. The volume average particle size of the resin particles is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of obtaining good fixing property and high image density, however, it is preferably from 10 nm to 1,000 nm, more preferably from 10 nm to 200 nm, and particularly preferably from 10 nm to 100 nm. The volume average particle size can be measured, for example, using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac-Bell Co., Ltd.). The resin content is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of fixation property and storage stability of the ink, however, the resin content is preferably from 1% by mass to 30% by mass, and more preferably from 5% by mass to 20% by mass, of the total amount of the ink. The particle size of the solid content in the ink is not particularly limited and can be appropriately selected depending on the purpose, but in terms of improving image quality such as ejection stability and image density, the maximum frequency in terms of maximum number is preferably 20 nm or more and 1000 nm or less, more preferably 20 nm or more and 150 nm or less. The solid content includes resin and pigment particles. The particle size can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0025] <Additives> If necessary, surfactants, antifoaming agents, antiseptics, antifungals, rust inhibitors, pH adjusters, etc. may be added to the ink.

[0026] <Surfactant> As the surfactant, any of silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used.

[0027] Silicone surfactants are not particularly limited and can be appropriately selected according to purpose.Among them, those that do not decompose even at high pH are preferred, such as side chain modified polydimethylsiloxane, both end modified polydimethylsiloxane, one end modified polydimethylsiloxane, side chain both end modified polydimethylsiloxane, etc., and those having polyoxyethylene group or polyoxyethylene polyoxypropylene group as modified group are particularly preferred because they show good properties as aqueous surfactants.In addition, polyether modified silicone surfactants can also be used as the silicone surfactant, such as a compound in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane.

[0028] As the fluorosurfactant, for example, perfluoroalkylsulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chain are particularly preferred because they have low foaming properties. As the perfluoroalkylsulfonic acid compounds, for example, perfluoroalkylsulfonic acid, perfluoroalkyl sulfonate, etc. are included. As the perfluoroalkyl carboxylic acid compounds, for example, perfluoroalkyl carboxylic acid, perfluoroalkyl carboxylate, etc. are included. As the polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chain, for example, sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups on the side chains, salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups on the side chains, etc. are included. As the counter ions of the salts in these fluorosurfactants, Li, Na, K, NH 4 , N.H. 3 CH 2 CH 2 OH, NH 2 (CH 2 CH 2 OH) 2 , NH(CH 2 CH 2 OH) 3 etc.

[0029] Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.

[0030] Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol. Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, polyoxyethylene alkyl ether sulfates, etc. These may be used alone or in combination of two or more.

[0031] The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the silicone surfactant include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end side-chain modified polydimethylsiloxane. Polyether-modified silicone surfactants having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferred because they exhibit good properties as an aqueous surfactant. Such surfactants may be appropriately synthesized or commercially available products, such as those available from BYK-Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd. The polyether-modified silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, it can be a surfactant represented by the general formula (S-1) in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylpolysiloxane. [ka] General formula (S-1) (In the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R' represents an alkyl group.) As the polyether-modified silicone surfactant, commercially available products can be used, such as KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (Nihon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (BYK-Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), and the like.

[0032] The fluorine-based surfactant is preferably a compound having 2 to 16 fluorine-substituted carbon atoms, and more preferably a compound having 4 to 16 fluorine-substituted carbon atoms.

[0033] Examples of the fluorine-based surfactant include perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains. Among these, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chains are preferred because they have low foaming properties, and in particular, fluorine-based surfactants represented by general formulas (F-1) and (F-2) are preferred. [ka] General formula (F-1) In the compound represented by the above general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility. C n F 2n+1- CH 2 CH(OH)CH 2 -O-(CH 2 CH 2 O)a -Y General formula (F-2) In the compound represented by the above general formula (F-2), Y is H or CnF 2n+1 where n is an integer from 1 to 6, or CH 2 CH(OH)CH 2 -CnF 2n+1 where n is an integer between 4 and 6, or CpH 2p+1 where p is an integer from 1 to 19. a is an integer from 4 to 14. As the above fluorosurfactant, a commercially available product may be used. Examples of commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, and FC-431 (all manufactured by Sumitomo 3M Limited); Megafa F-470, F-1405, F-474 (all manufactured by Dainippon Ink & Chemicals, Inc.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours); FT-110, FT PF-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by NEOS Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and the like. Among these, FS-3100, FS-34, FS-300 manufactured by Chemours Co., Ltd., FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by NEOS Co., Ltd., Polyfox PF-151N manufactured by Omnova, and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferred from the viewpoint of achieving good printing quality, particularly improved color development, penetration into paper, wettability, and dye uniformity. The content of the surfactant in the ink is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of excellent wettability and ejection stability and improved image quality, the content is preferably from 0.001% by mass to 5% by mass, and more preferably from 0.05% by mass to 5% by mass.

[0034] The HLB value of the surfactant is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 8 or less, more preferably 4 or less. Here, the HLB value is defined by the following formula (Griffin method), and is an index showing the balance between the hydrophilic group and the lipophilic group of a surfactant. HLB value = 20 × (sum of formula weights of hydrophilic parts / molecular weight) (Griffin method) The HLB value ranges from 0 to 20, with the closer to 0 the higher the lipophilicity, and the closer to 20 the higher the hydrophilicity.

[0035] As the surfactant satisfying the HLB value, a commercially available product can be used. Examples of the commercially available product include Silface SAG005 (HLB value: 7.0), Silface SAG008 (HLB value: 7.0) (all manufactured by Nissin Chemical Industry Co., Ltd.), FZ2110 (HLB value: 1.0), FZ2166 (HLB value: 5.8), SH-3772M (HLB value: 6.0), L7001 (HLB value: 7.4), SH-3773M (HLB value: 8.0) (all manufactured by Toray Dow Co., Ltd.), KF-945 (HLB value: 4.0), KF-6017 (HLB value: 4.5) (all manufactured by Shin-Etsu Chemical Co., Ltd.), and FormBan MS-575 (manufactured by Ultra Additives Inc., HLB value: 5.0).

[0036] <Antifoaming agent> The defoaming agent is not particularly limited, and examples thereof include silicone-based defoaming agents, polyether-based defoaming agents, and fatty acid ester-based defoaming agents. These may be used alone or in combination of two or more. Among these, silicone-based defoaming agents are preferred because of their excellent foam breaking effect.

[0037] <Preservative and fungicide> There are no particular restrictions on the antiseptic and antifungal agent, and examples thereof include 1,2-benzisothiazolin-3-one.

[0038] <pH adjuster> There are no particular restrictions on the pH adjuster as long as it can adjust the pH to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine. There are no particular restrictions on the physical properties of the ink, and it can be appropriately selected according to the purpose. For example, the viscosity, surface tension, pH, etc. are preferably in the following ranges. The viscosity of the ink at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, more preferably 5 mPa·s or more and 25 mPa·s or less, from the viewpoints of improving the printing density and the quality of characters and obtaining good dischargeability. Here, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used to measure the viscosity. The measurement conditions are as follows: at 25°C, with a standard cone rotor (1°34’×R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and it can be measured in 3 minutes. The surface tension of the ink is preferably 35 mN / m or less, more preferably 32 mN / m or less, at 25°C, from the viewpoints of the ink being preferably leveled on the recording medium and shortening the drying time of the ink. The pH of the ink is preferably 7 to 12, more preferably 8 to 11, from the viewpoint of preventing corrosion of the metal members in contact with the liquid.

[0039] <Recording medium> There are no particular restrictions on the recording medium, and ordinary paper, glossy paper, special paper, cloth, etc. can be used, but good image formation is also possible using a non-permeable substrate. The non-permeable substrate is a substrate having a surface with low water permeability and absorbency, and includes materials that have a large number of cavities inside but do not open to the outside. More quantitatively, in the Bristow method, the water absorption amount from the start of contact to 30 msec 1 / 2 is 10 mL / m 2 or less. As the non-permeable substrate, for example, a plastic film such as a polyvinyl chloride resin film, a polyethylene terephthalate (PET) film, a polypropylene film, a polyethylene film, or a polycarbonate film can be suitably used.

[0040] The polypropylene and polyethylene are not particularly limited, and examples thereof include AR1025, AR1056, AR1082, EC1082, 1082D, 1073D, 1056D, 1025D, and FR1073 (Asahi DuPont Flashspan). Products Co., Ltd.), P2002, P2102, P2108, P2161, P2171, P2111, P4266, P5767, P3162, P6181, P8121, P1162, P1111, P1128, P1181, P1153, P1157, P1146, P1147, P1171 (Toyobo Co., Ltd.), YPI, Aqua Yupo, Super Yupo, Ultra Yupo, New Yupo, Yupo Illumination Paper, Yupo Building Materials Paper, Yupo High Gloss, Yupo Jet, Metallic Yupo (Yupo Corporation), etc.

[0041] <Recordings> The ink recorded matter of the present invention comprises an image formed on a recording medium using the ink of the present invention. A recorded matter can be obtained by recording using an inkjet recording apparatus and an inkjet recording method.

[0042] <Recording device and recording method> The ink according to one embodiment of the present invention can be suitably used in various recording devices using an inkjet recording method, such as printers, facsimile machines, copying machines, multi-function printer / fax / copier machines, and three-dimensional modeling devices. In this application, the recording apparatus and recording method refer to an apparatus capable of ejecting ink or various treatment liquids onto a recording medium, and a method of recording using the apparatus. The recording medium refers to an object onto which ink or various treatment liquids can be attached even temporarily. This recording device can include not only a head portion that ejects ink, but also means related to feeding, transporting, and discharging the recording medium, as well as other devices called pre-processing devices and post-processing devices.

[0043] The recording apparatus and the recording method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, a means for heating and drying the printed surface and the back surface of the recording medium. The heating means and the drying means are not particularly limited, but for example, a hot air heater and an infrared heater can be used. Heating and drying can be performed before, during, or after printing. When an infrared heater is used, at least a near-infrared irradiation device is provided.

[0044] Known near-infrared irradiation devices are devices consisting of a halogen lamp and a reflecting mirror. Some products have been commercialized that incorporate a halogen heater into the reflecting mirror to create a heating unit that achieves efficient heating, such as the UH-USC-CL300, UHUSC-CL700, UH-USC-CL1000, UH-USD-CL300, UHUSD-CL700, UH-USD-CL1000, UH-MA1-CL300, UHMA1-CL700, and UH-MA1-CL1000 (all manufactured by Ushio Electric).

[0045] Furthermore, the recording apparatus and recording method are not limited to those that visualize meaningful images such as characters and figures with ink. For example, those that form patterns such as geometric designs and those that create three-dimensional images are also included. Furthermore, unless otherwise specified, the recording apparatus includes both serial type apparatuses that move a discharge head and line type apparatuses that do not move a discharge head. Furthermore, the recording device includes not only desktop type but also wide recording device capable of printing on A0 size recording media and continuous feed printer capable of using continuous paper wound in a roll as a recording medium. An example of a recording device will be described with reference to Figs. 2 and 3. Fig. 2 is a perspective view of the device. Fig. 3 is a perspective view of a main tank. An image forming device 400 as an example of a recording device is a serial type image forming device. A mechanism unit 420 is provided in an exterior 401 of the image forming device 400. Each ink storage unit 411 of the main tanks 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is formed by a packaging material such as an aluminum laminate film. The ink storage unit 411 is stored in a storage container case 414 made of plastic, for example. As a result, the main tanks 410 are used as ink cartridges of each color. On the other hand, a cartridge holder 404 is provided at the back side of the opening when the cover 401c of the apparatus body is opened. A main tank 410 is detachably attached to the cartridge holder 404. As a result, each ink outlet 413 of the main tank 410 communicates with an ejection head 434 for each color via a supply tube 436 for each color, and ink can be ejected from the ejection head 434 to a recording medium.

[0046] This recording apparatus can include not only a portion that ejects ink, but also devices called pre-processing devices and post-processing devices. As an embodiment of the pre-treatment device and post-treatment device, a liquid storage section having a pre-treatment liquid and a liquid ejection head, similar to the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y), and the like, are added, and the pre-treatment liquid and the post-treatment liquid are ejected by an inkjet recording method. As another embodiment of the pre-treatment device and the post-treatment device, there is an embodiment in which a pre-treatment device and a post-treatment device using a method other than the inkjet recording method, for example, a blade coating method, a roll coating method, or a spray coating method, are provided.

[0047] The ink can be used in a wide variety of ways, including, but not limited to, inkjet recording, blade coating, gravure coating, bar coating, roll coating, dip coating, curtain coating, slide coating, die coating, and spray coating.

[0048] In the present invention, the terms image formation, recording, printing, printing, etc. are all synonymous. EXAMPLES

[0049] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, "parts" means "parts by mass" and "%" means "% by mass" except in the evaluation criteria.

[0050] (Example of Pigment Dispersion Preparation) <Preparation of Black Pigment Dispersion> The materials for the black pigment dispersion shown below were premixed and then circulated and dispersed for 7 hours in a disk-type bead mill (KDL model, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls with a diameter of 0.3 mm) to obtain a self-dispersed black pigment dispersion (pigment solids concentration: 20% by mass). [Black pigment dispersion material] Carbon black pigment (product name: Monarch 800, manufactured by Cabot Corporation) 20 parts by weight Anionic surfactant (product name: Paionin A-51-B, manufactured by Takemoto Oil Co., Ltd.) 2 parts by weight Ion-exchanged water 78 parts by weight

[0051] <Ink preparation example 1> The ink materials shown below were mixed and stirred, and filtered through a 5 μm filter (Minisart, manufactured by Sartorius) to obtain the ink of Example 1. [Ink materials] Black pigment dispersion 15 parts by weight Superflex 300 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyurethane resin, solid content concentration: 30% by mass) 23.3 parts by mass KF-945 (siloxane surfactant, manufactured by Shin-Etsu Chemical Co., Ltd., HLB: 4.0) 2 parts by weight 1,2-propanediol (boiling point 187°C) 15 parts by weight 2-Ethyl-1,6-hexanediol (boiling point 243°C) 5 parts by mass Diethylene glycol diethyl ether (boiling point 188°C, glycol ether) 5 parts by mass 3-Methoxy-3-methylbutanol (boiling point 174°C, glycol ether) 5 parts by mass Proxel LV (Avecia preservative) 0.1 parts by weight Ion-exchanged water 29.6 parts by weight

[0052] <Ink Preparation Examples 2-21> Inks 2 to 21 were prepared in the same manner as Ink 1 using the formulations shown in Tables 1 to 4.

[0053] [Table 1]

[0054] [Table 2]

[0055] [Table 3]

[0056] [Table 4]

[0057] Details of the materials in Tables 1 to 4 are as follows. [resin] J-450 (styrene acrylic resin particles, non-volatile content 42%, Johnson Polymer) [Surfactants] · KF-6017 (siloxane surfactant, manufactured by Shin-Etsu Chemical Co., Ltd.) ·SH-3773M (siloxane surfactant, manufactured by Toray Dow)

[0058] (Examples 1 to 19 and Comparative Examples 1 to 2) In Examples 1 to 19 and Comparative Examples 1 and 2, inks 1 to 21 as shown in Tables 1 to 4 were loaded into modified inkjet printer IPSiO GXe5000 (manufactured by Ricoh Co., Ltd.) to form an image forming apparatus, and solid images were printed at a resolution of 600 dpi on OK Topcoat+ (manufactured by Oji Paper Co., Ltd.) as a recording medium using these image forming apparatuses. The modified IPSiO GXe5500 has a nozzle plate with at least two nozzle holes and a piezoelectric element, and the number of nozzle holes on the surface of the nozzle plate is 20 / mm on average. 2 The head was replaced with one manufactured so that the distance between adjacent nozzle holes in the direction approximately perpendicular to the transport direction of the recording medium was 250 μm, and the head was modified to enable image production with a high density nozzle head. The image forming apparatuses of Examples 1 to 19 and Comparative Examples 1 and 2 were evaluated for "drying property," "ejection stability," "fixing property (beading)," "abrasion resistance," and "initial filling property" as follows. The results are shown in Table 5.

[0059] <Drying> A filter paper was pressed against the solid image formed on the recording medium, the transfer condition to the filter paper was visually observed, and the drying property was evaluated based on the following evaluation criteria. If the evaluation result was "B" or higher, the image was usable. [Evaluation Criteria] A: Almost no pigment transfer to the filter paper is observed. B: Some pigment transfer is observed. C: Pigment transfer is evident.

[0060] <Adhesion (beading)> The solid image formed on the recording medium was visually observed for unevenness in recording and the "fixing ability (beading)" was evaluated based on the following evaluation criteria. If the evaluation result was "B" or higher, the recording medium was usable. [Evaluation Criteria] A: Very good (no beading at all) B: Good (slight beading observed) C: Normal (with beading) D: Poor (significant beading)

[0061] <Abrasion resistance> A solid image formed on a recording medium was rubbed with a cotton cloth 10 times, and the degree of pigment transfer to the cotton cloth was visually observed and evaluated according to the following criteria. If the evaluation result was "B" or higher, the image was usable. [Evaluation Criteria] A: Almost no pigment transfer to the cotton fabric. B: Some pigment transfer is observed. C: Pigment transfer is evident.

[0062] <Initial filling properties> Immediately after filling an inkjet printer (IPSiO GX-5000, manufactured by Ricoh Co., Ltd.) that had not been filled with ink, a nozzle check pattern was printed out using print setting maintenance to check for nozzle clogs, and the "initial filling property" was evaluated based on the following evaluation criteria. If the evaluation result was "B" or higher, the ink was usable. [Evaluation Criteria] A: No missing nozzles B: The number of missing nozzles is between 1 and 10 C: 10 or more nozzles have been missing

[0063] <Discharge stability> A chart was created that filled 5% of the area of ​​A4 size paper with a solid image. Next, the created chart was printed out continuously on recording media OK Topcoat+ (Oji Paper) in 5 sets of 200 sheets, and evaluated based on the irregular discharge of each nozzle after printing. The print mode used was a mode that was modified from the plain paper user settings of the driver attached to the printer to "plain paper - standard fast" mode and changed to "no color correction." If the above evaluation result was "B" or higher, it was ready for practical use. [Evaluation Criteria] A: No disturbance in discharge B: Some irregular discharge C: Discharge is disturbed or there are areas where discharge is not performed

[0064] [Table 5]

[0065] It is clear that Example 1 is a preferred embodiment of the present invention, and is excellent in drying properties, initial filling properties and ejection stability, and further, can provide images having high abrasion resistance and fixability. Example 2 is an example that does not contain an alcohol-based solvent having a boiling point of 180° C. or less, and the drying property was inferior to that of Example 1. Example 3 is an example in which glycol ether is not used as the alcohol-based solvent, and the fixing performance was inferior to that of Example 1. In Example 4, the alcohol solvent with a boiling point of 250° C. or less was less than 50 parts by weight of the total solvent, and compared with Example 1, the initial filling property and the discharge stability were inferior. Example 5 is an example in which the amount of resin added is slightly small, and as a result, compared to Example 1, the abrasion resistance was inferior. Example 6 is an example in which the amount of resin added is slightly large, and as a result, the ejection stability was inferior to that of Example 1. Example 7 is an example in which the type of resin is not urethane, and the result was inferior to Example 1 in abrasion resistance. Example 8 is an example that does not contain a solvent having a surface tension of 30 mN / m or less, and the fixing property was inferior to that of Example 1. Examples 9 and 10 are examples that do not contain a surfactant having an HLB value of 4 or less, and compared with Example 1, the fixing property and abrasion resistance were inferior. It can be seen that Examples 11 to 13 have a preferable amount of glycol ether added as an alcohol-based solvent, and provide images that are excellent in drying properties, initial filling properties and ejection stability, as well as high abrasion resistance and fixability. Examples 14 to 16 are examples in which the amount of glycol ether added as the alcohol-based solvent was slightly small, and compared to Example 1, the drying properties and fixation properties were inferior. Examples 17 to 19 are examples in which the amount of glycol ether added as the alcohol-based solvent was slightly large, and compared to Example 1, the ejection stability was inferior.

[0066] Comparative Example 1 is an example in which an alcohol-based solvent having a boiling point higher than 250° C. was used, and the results were inferior to those of the Examples in terms of drying properties, ejection stability, initial filling properties, and fixability. Comparative Example 2 is an example in which no alcohol-based solvent was used, and the results showed inferior discharge stability and initial filling properties compared to the Examples.

[0067] From the results in Table 5, it can be seen that the ink of the present invention is suitable for use in combination with a head with a high nozzle density, and enables high-speed printing. Furthermore, the inks of Examples 1 to 19 were excellent in drying property, ejection stability, abrasion resistance, fixation property, and initial filling property.

[0068] The aspects of the embodiment of the present invention are as follows, for example. <1> a nozzle plate having at least two nozzle holes and a piezoelectric element; and an ink containing an alcohol-based organic solvent having a boiling point of 250° C. or less; The number of the nozzle holes on the surface of the nozzle plate is 10 / mm on average. 2 That's all. The image forming apparatus is characterized in that the distance between adjacent nozzle holes in a direction substantially perpendicular to the transport direction of the recording medium is 150 μm or more and 500 μm or less. <2> The boiling point of the alcohol-based organic solvent is 180° C. or lower. <1> The image forming apparatus according to claim 1, <3> The alcohol-based organic solvent is a glycol ether. <1> from <2> 13. The image forming apparatus according to claim 12, <4> The content of the alcohol-based organic solvent is 50% by mass or more based on the total amount of the ink. <1> from <2> 13. The image forming apparatus according to claim 12, <5> the ink contains a resin, The content of the resin is 5% by mass or more and 10% by mass or less with respect to the total amount of the ink. <1> from <2> 13. The image forming apparatus according to claim 12, <6> The resin is a urethane resin. <5> The image forming apparatus according to claim 1, <7> The alcohol-based organic solvent has a surface tension of 30 mN / m or less at 25° C. <1> from <2> 13. The image forming apparatus according to claim 12, <8> The ink contains a surfactant, The surfactant is a silicone surfactant having an HLB value of 4 or less. <1> from <2> 13. The image forming apparatus according to claim 12, [Prior art documents] [Patent documents]

[0069] [Patent Document 1] JP 2018-048925 A [Explanation of symbols]

[0070] 400 Image forming device 401 Exterior 401c cover 404 Cartridge Holder 410, 410k, 410c, 410m, 410y main tank 411 Ink storage unit 413 Ink outlet 414 Storage container case 420 Mechanism Department 434 Discharge Head 436 Supply Tube L Ink storage container

Claims

1. a nozzle plate having at least two nozzle holes and a piezoelectric element; and an ink containing an alcohol-based organic solvent having a boiling point of 250° C. or less; The number of the nozzle holes on the surface of the nozzle plate is 10 / mm on average. ２ That's all.

13. An image forming apparatus, comprising: a nozzle hole having a width of 150 μm to 500 μm, the nozzle hole being spaced apart from each other in a direction substantially perpendicular to a direction in which a recording medium is transported.

2. 2. The image forming apparatus according to claim 1, wherein the alcohol-based organic solvent has a boiling point of 180[deg.] C. or lower.

3. 3. The image forming apparatus according to claim 1, wherein the alcohol-based organic solvent is a glycol ether.

4. 3. The image forming apparatus according to claim 1, wherein a content of the alcohol-based organic solvent is 50% by mass or more with respect to a total amount of the ink.

5. the ink contains a resin, 3. The image forming apparatus according to claim 1, wherein a content of the resin is 5% by mass or more and 10% by mass or less with respect to a total amount of the ink.

6. 6. The image forming apparatus according to claim 5, wherein the resin is a urethane resin.

7. 3. The image forming apparatus according to claim 1, wherein the alcohol-based organic solvent has a surface tension of 30 mN / m or less at 25°C.

8. The ink contains a surfactant, 3. The image forming apparatus according to claim 1, wherein the surfactant is a silicone-based surfactant having an HLB value of 4 or less.

Images