Liquid discharge unit, printing device and printing method

Abstract

To provide a liquid discharge unit that when performing printing by discharging liquid with high viscosity which is used for a road surface, wall surfaces of architectural structures such as an exterior and an interior, wall surfaces of civil engineering structures such as a bridge and a tunnel and a porous material, can stably discharge the liquid through a nozzle hole which has been put in an uncapped state (a state where a nozzle is not capped in order to preventing the nozzle from drying and is exposed).SOLUTION: The liquid discharge unit comprises a nozzle part that discharges liquid with high viscosity. The nozzle part comprises a nozzle hole, a nozzle plate having the nozzle hole, a liquid chamber that supplies liquid to the nozzle hole, and a needle valve that closes or opens the nozzle hole at a tip thereof, while moving back and forth in the liquid chamber, where a liquid repellent layer whose surface free energy is less than 29 mJ / m2 is formed on a surface of the nozzle plate.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a liquid ejection unit, a printing apparatus, and a printing method.

Background Art

[0002] Conventionally, solvent-type or water-based paints have been applied to road surfaces, floors, and building walls by spraying, brushing, or rolling.

[0003] Conventionally, when painting road surfaces, building walls such as exterior and interior finishes, civil engineering structures such as bridges and tunnels, and porous substrates, there has been a method of ejecting ink from a nozzle by an inkjet method for painting. In the inkjet method, since ink droplets are applied to the substrate in dot form, it is possible to provide a painting with high-definition characters and patterns that are impossible with conventional spraying, brushing, or rolling methods.

[0004] Also, as a nozzle, a paint injection nozzle and its control method have been proposed that can prevent liquid leakage when the nozzle hole is closed and obtain stable coating accuracy when the nozzle is open (see, for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0005] One embodiment of the present invention is for use on road surfaces, building walls such as exterior and interior finishes, civil engineering structures such as bridges and tunnels, and porous substrates. When printing by ejecting a high-viscosity liquid, it is an object to provide a liquid ejection unit that can stably eject from a nozzle hole in a state where capping is not performed (a state where the nozzle is exposed without a lid for preventing nozzle drying).

Means for Solving the Problems

[0006] A liquid ejection unit according to one embodiment of the present invention as means for solving the above problems is A liquid ejection unit having a nozzle unit that ejects a liquid, The nozzle unit includes a nozzle hole, a nozzle plate having the nozzle hole, a liquid chamber that supplies liquid to the nozzle hole, and a needle valve that closes or opens the nozzle hole at its tip while making a reciprocating motion in the liquid chamber. On the surface of the nozzle plate, there is a liquid-repellent layer with a surface free energy of less than 29 mJ / m 2 The liquid ejection unit is characterized by having a liquid-repellent layer with a surface free energy of less than 29 mJ / m

Advantages of the Invention

[0007] According to one embodiment of the present invention, when printing by ejecting a high-viscosity liquid used for a road surface, a wall surface of a building such as an exterior or interior finish, a wall surface of a civil engineering structure such as a bridge or a tunnel, and a porous substrate, it is possible to provide a liquid ejection unit that can stably eject from a nozzle hole in a state where capping is not performed (a state where the nozzle is exposed without a lid for preventing drying of the nozzle).

Brief Description of the Drawings

[0008]

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0009] (Liquid ejection portion) A liquid ejection portion according to an embodiment of the present invention is a liquid ejection portion having a nozzle portion that ejects a liquid, wherein the nozzle portion includes a nozzle hole, a nozzle plate that forms the nozzle hole, a liquid chamber that supplies liquid to the nozzle hole, and a needle valve that closes or opens the nozzle hole at a tip while making a reciprocating motion in the liquid chamber, and is characterized in that a liquid repellent layer is provided on the surface of the nozzle plate and the formation surface of the nozzle hole 2.

[0010] In the nozzle presented in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2022-64482), when printing using a conventional high-viscosity ink used for painting on a road surface, a wall surface of a building such as an exterior or interior, a wall surface of a civil engineering structure such as a bridge or a tunnel, and a porous substrate, when attempting to eject from a nozzle in a state where the nozzle was not capped during printing, there was a problem that stable ejection from the nozzle was not possible. As a result, depending on the printed image, there were also nozzles that remained in a state where ejection did not occur during printing for a long time, resulting in problems such as displacement of the ink landing position and nozzle dropout due to non-ejection.

[0011] Therefore, as a result of intensive studies by the present inventors, the following findings were obtained. Specifically, in the nozzle portion of the liquid ejection portion, the surface free energy is 29 mJ / m on the surface of the nozzle plate and the formation surface of the nozzle hole 2 2By having a liquid-repellent layer that is less than a certain thickness, the surface free energy of the nozzle plate is reduced, making it easier to maintain the ink-repellent property against ink. Therefore, by maintaining the ink-repellent property against the ink thickened by drying, the ejection deflection can be suppressed. As a result, when printing with high-viscosity ink, stable ejection can be achieved even from a liquid ejection portion that has not been capped. The high-viscosity ink mentioned above means ink having a viscosity of 1,000 mPa·s or more at a shear rate of 1 (1 / s).

[0012] Hereinafter, a liquid ejection portion according to an embodiment of the present invention will be described with reference to the drawings.

[0013] <First Embodiment> FIG. 1 is a schematic cross-sectional view of an example showing an enlarged view of a nozzle hole and the tip of a needle valve in a liquid ejection portion according to the first embodiment of the present invention. The liquid ejection portion according to the first embodiment has a nozzle portion 10. The nozzle portion 10 includes a base 1, a nozzle hole 2 through which liquid is ejected, a nozzle plate 3 that forms the nozzle hole 2, a liquid chamber 4 that supplies liquid to the nozzle hole, and a needle valve 5 disposed in the liquid chamber 4. The outer surface of the nozzle plate 3 and the formation surface of the nozzle hole 2 have a liquid-repellent layer 6. The water-repellent layer 6 is preferably provided on the entire outer surface of the nozzle plate 3 and the formation surface of the nozzle hole 2. Also, although not shown in FIG. 1, the liquid ejection portion according to the first embodiment may include a drive mechanism that moves the needle valve 5 forward and backward with respect to the nozzle hole 2.

[0014] The base 1 is a member that forms the outer wall of the nozzle portion 10, and there is no particular limitation on the material, and it can be appropriately selected according to the purpose.

[0015] The nozzle hole 2 is a hole through which liquid is ejected. The diameter of the nozzle hole 2 is not particularly limited and can be appropriately selected according to the purpose, but it is 50 μm or more, and more preferably 100 μm or more. When the diameter is 50 μm or more, it is possible to discharge a liquid or the like used for a road surface, a wall surface of a building such as an exterior or interior finish, a wall surface of a civil engineering structure such as a bridge or a tunnel, and a porous substrate.

[0016] The nozzle plate 3 forms the nozzle hole 2 and has a liquid-repellent layer 6 on the outer surface and the formation surface of the nozzle hole 2. The outer surface of the nozzle plate is the surface of the nozzle plate opposite to the side where the liquid chamber 4 is disposed.

[0017] The liquid-repellent layer 6 is a layer having a surface free energy of less than 29 mJ / m 2 When the nozzle portion 10 has the liquid-repellent layer 6 having a surface free energy of less than 29 mJ / m 2 it becomes easier to maintain the ink-repellent property against ink, and by maintaining the ink-repellent property against the ink thickened by drying, the discharge deflection can be suppressed. As a result, when printing using an ink having a high viscosity and a high solid content, it is possible to stably discharge from a liquid discharge portion that has not been capped.

[0018] The method for calculating the surface free energy of the water-repellent layer is not particularly limited and can be appropriately selected according to the purpose. For example, it can be measured by the following procedure using a contact angle meter DMo501 (manufactured by Kyowa Interface Science Co., Ltd.). Specifically, the contact angles of three liquid samples with known surface free energies are measured for the water-repellent layer, and the surface free energy of the water-repellent layer can be calculated by solving a system of simultaneous equations. Let the surface free energy of the water-repellent layer be γ s the dispersive force component of the surface energy of the water-repellent layer be γ sd the dipole component of the surface energy of the water-repellent layer be γ sp the hydrogen bond component of the surface energy of the water-repellent layer be γ sh the surface free energy of the liquid sample be γ L the dispersive force component of the surface energy of the liquid sample be γ Ld, let the dipole component of the surface energy of the liquid sample be γ Lp , let the hydrogen bond component of the surface energy of the liquid sample be γ Lh , when the contact angle of the liquid sample on the water-repellent layer is θ, the following formulas (1), (2) and (3) hold. [Chemical formula] For each γ with respect to the water-repellent layer L , γ Ld , γ Lp , γ Lh , for 3 kinds of liquid samples with known γ, measure the contact angle θ respectively and substitute it into the above formula (3), then three formulas with γ sd , γ sp , γ sh as variables can be obtained. By solving these formulas, γ sd , γ sp , γ sh can be obtained. Substitute the obtained γ sd , γ sp , γ sh into (1), then the surface free energy γ of the water-repellent layer s can be obtained. The above formulas (1) and (2) are the formulas in the theory of Kitazaki-Hata. The above formula (3) is a formula obtained by substituting the formula of Hata-Kitazaki and the extended Harkins formula into Dupre's formula and further transforming Young-Dupre's formula using the substituted formula. In addition to Kitazaki-Hata, there are also the theoretical formulas of Owens-Wendt and Kaelble-Uy. Measure the contact angles of 2 kinds of liquid samples with known surface free energy with respect to the water-repellent layer, substitute them into Young-Dupre's formula and solve the simultaneous equations to calculate the surface free energy of the water-repellent layer.

[0019] The liquid-repellent layer 6 preferably contains at least one of silicon (Si) and fluorine (F), and may contain other components as necessary.

[0020] Fluorine (F) may be contained in the liquid-repellent layer 6 as a fluorine compound. There are no particular restrictions on the fluorine compound, and it can be appropriately selected according to the purpose. For example, krytox FSL (manufactured by DuPont), krytox FSH (manufactured by DuPont), Fomblin Z (manufactured by Solvay Solexis), FLUOROLINKS 10 (manufactured by Solvay Solexis), Optool DSX (manufactured by Daikin Industries), FLUOROLINK C10 (manufactured by Solvay Solexis), Moresco Phospharol A20H (manufactured by Matsumura Oil Research Institute, Inc.), Moresco Phospharol ADOH (manufactured by Matsumura Oil Research Institute, Inc.), Moresco Phospharol DDOH (manufactured by Matsumura Oil Research Institute, Inc.), Fluorosurf FG5010 (manufactured by Fluorotechnology), Fluorosurf FG5020 (manufactured by Fluorotechnology), Fluorosurf FG5060 (manufactured by Fluorotechnology), Fluorosurf FG5070 (manufactured by Fluorotechnology), Durasurf DP-500 (manufactured by Harves), Durasurf DP-200 (manufactured by Harves), Durasurf DS-5400 (manufactured by Harves), Durasurf DH-100 (manufactured by Harves), H-405TH (manufactured by Harves), DH-610 (manufactured by Harves), DS-6500 (manufactured by Harves), DS-5800 (manufactured by Harves), DS-5935 (manufactured by Harves), etc. These may be used alone or in combination of two or more. Among these, modified perfluoropolyoxetane (Optool DSX manufactured by Daikin Industries) is preferred.

[0021] Silicon (Si) may be included in the liquid-repellent layer 6 as a silicon compound. There are no particular restrictions on the silicon compound, and it can be appropriately selected according to the purpose. For example, silicone resins and the like can be mentioned. A silicone resin is a resin having a siloxane bond formed by silicon (Si) and oxygen (O) as a basic skeleton. Silicone resins are commercially available in various forms such as oils, resins, and elastomers, and have various properties such as heat resistance, mold release properties, defoaming properties, and adhesiveness in addition to the important water repellency in the present invention. Silicone resins include room temperature curing, heat curing, ultraviolet curing types, etc., and can be selected according to the production method and intended use.

[0022] In one embodiment of the present invention, a treatment film may be provided between a liquid repellent layer containing at least one of silicon (Si) and fluorine (F) and a substrate. The treatment film is not particularly limited and can be appropriately selected according to the purpose. For example, an oxide film layer of SiO 2 , a film in which Si and a transition metal (for example, tantalum, niobium, titanium, hafnium, zirconium, tungsten) are bonded via O, etc. can be mentioned. When it is an oxide film of SiO 2 , moisture is less likely to permeate, so the substrate is less likely to corrode. Also, when it is a film in which Si and a transition metal are bonded via O, a passive film having the characteristics of a poorly soluble transition metal oxide at a wide range of pHs is formed, and a more stable film can be formed even in acidic and alkaline conditions.

[0023] When forming a liquid repellent layer containing at least one of silicon (Si) and fluorine (F), a silanol compound having a silanol group (Si-OH) may be contained in the liquid repellent layer, and the Si-OH may be condensation-bonded with the substrate or the treatment film via the silanol group. By containing the silanol group Si-OH in the liquid repellent layer, the silanol groups of the substrate and the treatment film form hydrogen bonds. Furthermore, by setting the temperature to room temperature or higher, the dehydration condensation reaction of the hydrogen bond part proceeds, and Si forms a covalent bond with the substrate and the treatment film via O, thereby improving the adhesion. In addition, the silanol groups in the liquid repellent layer react with each other to form a siloxane bond Si-O-Si, thereby improving the strength of the liquid repellent layer. Furthermore, the silanol compound in the liquid repellent layer complements oxygen for the oxygen deficiency in the surface oxidation state of the substrate, thereby homogenizing the substrate surface state, eliminating the sites that become the starting points of corrosion, and improving the corrosion resistance.

[0024] That at least one of silicon (Si) and fluorine (F) is contained in the liquid-repellent layer 6 can be measured by XPS (X-ray Photoelectron Spectroscopy), TOF-SIM (Time-of-Flight Secondary Ion Mass Spectrometry), EDS or EPMA of an electron microscope, X-ray fluorescence, or the like. Further, by analyzing elements in a depth profile in a direction perpendicular to the outermost surface of the liquid-repellent layer from the outermost surface of the liquid-repellent layer using XPS and TOF-SIM toward the surface of the substrate or the needle valve that contacts the liquid-repellent layer of the needle valve, it is possible to analyze silicon (Si) and fluorine (F) in the cross-sectional depth direction of the liquid-repellent layer 6.

[0025] The average thickness of the liquid-repellent layer 6 is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0.0001 μm or more and 5 μm or less. In order to make it lower than the surface free energy of the water-repellent layer and improve the durability of the water-repellent layer against abrasion, when the water-repellent layer contains silicon (Si), it is more preferably 0.5 μm or more and 5 μm or less, and when the water-repellent layer contains fluorine (Si), it is more preferably 0.0005 or more and 0.02 μm or less.

[0026] The liquid chamber 4 has a structure for holding a liquid formed by a substrate 1 as an outer wall in the nozzle portion 10 and a nozzle plate 3 that forms the nozzle hole 2.

[0027] The needle valve 5 is provided inside the liquid chamber 4, and by the needle valve 5 advancing and retracting in the liquid chamber 4, the nozzle hole 2 can be closed or opened at the tip of the needle valve 5. The advancing and retracting operation of the needle valve 5 can be controlled by, for example, a drive mechanism. The pressure applied to the liquid chamber 4 and the liquid by the needle valve 5 is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0.2 MPa or more. When the pressure is 0.2 MPa or more, high-viscosity ink can be ejected.

[0028] The drive mechanism is not particularly limited and can be appropriately selected according to the purpose. Examples include an electromagnetic drive type drive mechanism and a drive mechanism using a piezoelectric element.

[0029] <Modification Example 1 of the First Embodiment> FIG. 2 is a schematic cross-sectional view of an example showing an enlarged view of a nozzle hole and a tip portion of a needle valve in a liquid discharge portion according to Modification Example 1 of the first embodiment of the present invention. The modification example of the first embodiment has a liquid repellent layer 6 not only on the outer surface of the nozzle plate 3 and the formation surface of the nozzle hole 2 but also on the formation surface of the liquid chamber 4 in the nozzle plate 3 (hereinafter sometimes referred to as "the inner surface of the nozzle plate 3") with respect to the first embodiment. Thereby, when discharging and printing a liquid having a higher viscosity than that of the first embodiment, it is possible to stably discharge from a nozzle that has not been capped.

[0030] <Modification Example 2 of the First Embodiment> FIG. 3 is a schematic cross-sectional view of an example showing an enlarged view of a nozzle hole and a tip portion of a needle valve in a liquid discharge portion according to Modification Example 2 of the first embodiment of the present invention. The modification example 2 of the first embodiment has a liquid repellent layer 6 also at the tip of the needle valve 5 with respect to the modification example 1 of the first embodiment. Thereby, when discharging and printing a liquid having a higher viscosity than that of the first embodiment and the modification example 1 of the first embodiment, it is possible to stably discharge from a nozzle that has not been capped.

[0031] FIG. 4 is a schematic configuration diagram showing an example of a liquid discharge portion according to an embodiment of the present invention, and is a diagram showing an example of a state when the nozzle is closed. Further, FIG. 5 is a schematic configuration diagram showing an example of a liquid discharge portion according to an embodiment of the present invention, and is a diagram showing an example of a state when the nozzle is open. In FIGS. 4 and 5, the liquid ejection unit of the present invention includes a nozzle hole 2 provided on the front surface of a substrate 1, an ink chamber 3 that supplies ink to the nozzle hole 2, a needle valve 4 that is in the ink chamber 3 and closes or opens the nozzle hole 2 at its tip, a movable iron core 8 fixed behind the needle valve, a fixed iron core 11 and an electromagnetic solenoid 12 provided facing the movable iron core 8, and a spring material 10 provided between the movable iron core 8 and the fixed iron core 11. The movable iron core 8, the spring material 10, the fixed iron core 11, and the electromagnetic solenoid 12 constitute an electromagnetic drive type drive mechanism for repeating the closing and opening operations of the needle valve 4 with respect to the nozzle hole 2.

[0032] An elastic diaphragm 7 is provided so as to surround the needle valve 4 in order to prevent the ink in the ink chamber 3 from flowing out into the drive mechanism accommodation space 9 that accommodates the above drive mechanism. Pressure P is applied to the ink in the ink chamber 3 via an ink input passage 5.

[0033] In order to prevent the pressurized ink from leaking out between the elastic diaphragm 7 and the needle valve 4, a pressure P similar to the pressure applied to the ink via a pressure passage 13 is applied to the gas or liquid in the drive mechanism accommodation space 9.

[0034] FIG. 4 shows a state where the needle valve 4 closes the nozzle hole 2. At this time, since no current flows through the solenoid 12, the movable iron core 8 and the subsequent needle valve 4 are pushed forward by the action of the spring material 10, and as a result, the nozzle hole 2 can be closed.

[0035] On the other hand, FIG. 5 shows a state where the needle valve 4 opens the nozzle hole 2. At this time, a current flows through the solenoid 12, the movable iron core 8 is attracted to the fixed iron core 11, and thus the needle valve 4 moves downward to open the nozzle hole 2.

[0036] As described above, by supplying, for example, a pulse current to the solenoid 12 and appropriately controlling it, the nozzle hole 2 can be opened and closed by the needle valve 4 to eject ink and print on a three-dimensional material.

[0037] 17 is a pressurized ink tank, which is connected to the ink chamber 3 via a circulation path 20. Ink is supplied from the ink tank 17 to the ink input passage 5, and the ink discharged from the ink output passage 6 returns to the ink tank 17 via a pump 18. Circulating the pressurized ink in this way can prevent the separation and precipitation of ink components, which helps to broaden the range of ink types that can be used.

[0038] A gap adjustment bolt 15 and a nut 16 are connected to the fixed iron core 11. By turning the nut 16, the position of the fixed iron core 11 can be changed, and this change range becomes the change range of the distance between the needle valve 4 and the nozzle hole 2, that is, the nozzle gap, and this can be adjusted with the bolt 15. 14 is a spring for preventing play of the screw.

[0039] The discharge amount of ink can be controlled by adjusting the energization time of the solenoid 12, that is, the length of the opening time of the nozzle hole 2.

[0040] By the action of the gap adjustment bolt 15 and the nut 16, if the nozzle gap is increased, the discharge amount of ink can be increased.

[0041] The liquid that can be used in one embodiment of the present invention is not particularly limited as long as it is fluid and can be discharged from the nozzle, and examples include ink, paint, treatment liquid, and the like. The liquid is a liquid used for painting road surfaces, exteriors, and porous substrates.

[0042] (Ink) Ink contains a solvent, a resin, and thickening particles, and further contains other components as required. The ink is an ink that exhibits pseudoplastic flow. After the ink is discharged onto asphalt or the like on the road surface, the viscosity of the ink increases, so it is difficult to penetrate into the road surface, and the coating film becomes thicker and the concealment is improved. Also, when the ink is discharged from the nozzle by the inkjet method, the viscosity of the ink decreases, so the discharge stability is improved. Also, on the wall surfaces of buildings such as exterior and interior finishes, and on the wall surfaces of civil engineering structures such as bridges and tunnels, after the ink is ejected, the viscosity of the ink increases, so that dripping of the ink can be suppressed while thickening the coating film on the wall surface to improve concealment and perform painting. Note that as the viscosity of the ink, -1 the viscosity at 25°C at a shear rate of 1S is preferably 1,000 mPa·s or more.

[0043] Since the ink exhibits pseudoplastic flow, after the ink is ejected onto asphalt on the road surface, etc., the viscosity of the ink increases, making it difficult for the ink to penetrate into the road surface, thickening the coating film and improving concealment. Also, when the ink is ejected from the nozzle by the inkjet method, the viscosity of the ink decreases, improving ejection stability.

[0044] The ink -1 preferably has a viscosity at 25°C at a shear rate of 1S of 1,000 mPa·s or more.

[0045] The ink preferably has a viscosity at 25°C at a shear rate of 5,000S of 130 mPa·s or less, and more preferably 30 mPa·s or more and 80 mPa·s or less from the viewpoint of obtaining more excellent ejection stability. -1

[0046] The method for measuring the viscosity is not particularly limited and can be appropriately selected according to the purpose. For example, it can be measured using MCR301 (manufactured by Anton Parr) with a cone plate (cone radius: 25 mm, cone angle: 1°).

[0047] <Thickening particles> The "thickening" of the thickening particles means that in a solution such as ink containing the particles, when the solution contains the particles, the viscosity increases as the shear rate decreases, and the viscosity decreases as the shear rate increases. 60 g of thickening particles are dispersed in 100 mL of water at 25°C, and the viscosity at a shear rate of 0.1S -1 is 100 mPa·s or more and 900,000 mPa·s or less, and at a shear rate of 5,000S-1 It means that the viscosity is 1 mPa·s or more and 200 mPa·s or less, and when the shear rate is decreased, the viscosity increases, and when the shear rate is increased, the viscosity decreases.

[0048] By including the thickening particles in the ink, the viscosity of the ink can be controlled according to the shear rate. Specifically, the viscosity of the ink at 25°C at a shear rate of 1 S -1 is controlled to be 3.00×10 3 mPa·s or more and 2.50×10 4 mPa·s or less, a thick ink coating film can be formed, which has excellent concealment of the substrate. Also, by controlling the viscosity of the ink at 25°C at a shear rate of 5,000 S -1 to 130 mPa·s or less, the ejection stability of the ink can be improved.

[0049] On the walls of buildings such as roads, exterior and interior decorations, and on the walls of civil engineering structures such as bridges and tunnels, a coating film resistant to impact and wear is required. Therefore, by including thickening particles, it is preferable to form a tough coating film resistant to impact and wear.

[0050] There are no particular restrictions on the thickening particles, and they can be appropriately selected according to the purpose. For example, fumed silica, precipitated silica, diatomaceous earth, bentonite, sepiolite, talc, calcium carbonate, barium sulfate, polyethylene oxide, etc. can be mentioned. These may be used alone or in combination of two or more. Among these, calcium carbonate and talc are preferable from the viewpoint of the toughness of the ink coating film. Also, mixed crystals may be used as the thickening particles. Also, the thickening particles and a non-particulate thickener may be used in combination. Examples of the non-particulate thickener include those that are resinous and melt in the paint to exhibit the effect of "thickening".

[0051] There are no particular restrictions on the calcium carbonate, and it can be appropriately selected according to the purpose. For example, commercially available products can be used. The commercially available products are not particularly limited and can be appropriately selected according to the purpose. For example, UP-G (manufactured by Imerys Specialties Japan Co., Ltd., solid content 100%), Lumina (manufactured by Maruo Calcium Co., Ltd., solid content 100%), Caltex 5 (Maruo Calcium Co., Ltd., solid content 100%), Super #2000 (manufactured by Maruo Calcium Co., Ltd., solid content 100%), Super SSS (Maruo Calcium Co., Ltd., solid content 100%), Softon 1500 (Bihoku Powder Chemical Industry Co., Ltd., solid content 100%), Softon 3200 (Bihoku Powder Chemical Industry Co., Ltd., solid content 100%), BF100 (Bihoku Powder Chemical Industry Co., Ltd., solid content 10%), Lighton A-5 (Bihoku Powder Chemical Industry Co., Ltd., solid content 100%), etc. can be mentioned.

[0052] There are no particular restrictions on the talc, and it can be appropriately selected according to the purpose. For example, commercially available products can be used. The commercially available products are not particularly limited and can be appropriately selected according to the purpose. For example, Nano Ace D-600 (Nippon Talc Co., Ltd., solid content 100%), etc. can be mentioned.

[0053] The content of the thickening particles is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 20.0% by mass or more and 55.0% by mass or less based on the total amount of the ink. Thereby, it becomes easier to control the viscosity of the ink.

[0054] <Resin> There are no particular restrictions on the resin, and it can be appropriately selected according to the purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic-styrene resin, acrylic-silicone resin, etc. can be mentioned. These may be used alone or in combination of two or more. In addition, as the resin, resin particles composed of these resins may be used. By making the resin particles into a state of a resin emulsion dispersed in a solvent as a dispersion medium, it is possible to obtain an ink by mixing with materials such as colorants and organic solvents. As the resin particles, those synthesized as appropriate may be used, or commercially available products may be used. These may be used alone or in combination of two or more kinds of resin particles.

[0055] The glass transition temperature of the resin is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of cracking of the coating film during the thick film formation, it is preferably 15°C or lower, more preferably 0°C or lower.

[0056] The method for measuring the glass transition temperature is not particularly limited and can be appropriately selected according to the purpose. For example, in the case of a resin emulsion, it can be determined as follows. Specifically, 4 g of the resin emulsion is placed in a petri dish made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) with a diameter of 50 mm so as to spread evenly, and dried at 50°C for 1 week to obtain a resin film. 5.0 mg is taken from the obtained resin film and placed in an aluminum sample container. The sample container is placed on a holder unit and set in an electric furnace. Next, in a nitrogen atmosphere, the temperature is raised from 0°C to 150°C at a heating rate of 10°C / min, then the temperature is lowered from 150°C to -80°C at a cooling rate of 5°C / min, and then the temperature is raised from -80°C to 150°C at a heating rate of 10°C / min to measure the DSC curve. From the obtained DSC curve, using the analysis program in the DSC-60 system, the inflection point during the second heating is analyzed by the midpoint method to obtain the glass transition point (Tg).

[0057] The content of the resin is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of the fastness of the dry film, it is preferably 5% by mass or more and 30% by mass or less. Note that the content indicates the content of the solid component of the resin.

[0058] The ratio (A / B) of the content (A) of the thickening particles to the solid content (B) of the resin is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.8 or more, more preferably 1.0 or more, and still more preferably 1.5 or more. When the ratio (A / B) is 0.8 or more, it has excellent discharge stability and is excellent in the concealability of the substrate by forming a thick coating film.

[0059] <Solvent> The solvent is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include organic solvents and water.

[0060] The organic solvent is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, polyhydric alcohols, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, and ethylene carbonate.

[0061] The polyhydric alcohols are not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of functioning as a wetting agent and obtaining excellent discharge stability, dihydric alcohols, trihydric alcohols, etc. can be mentioned.

[0062] Examples of the dihydric alcohol 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 the like. Examples of the trivalent alcohol include glycerin, 1,2,6 - hexanetriol, 2 - ethyl - 1,3 - hexanediol, ethyl - 1,2,4 - butanetriol, 1,2,3 - butanetriol, 2,2,4 - trimethyl - 1,3 - pentanediol, petriol, and the like.

[0063] There are no particular restrictions on the polyhydric alcohol alkyl ethers, and they can be appropriately selected according to the purpose. Examples include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like. There are no particular restrictions on the polyhydric alcohol aryl ethers, and they can be appropriately selected according to the purpose. Examples include ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, and the like.

[0064] There are no particular restrictions on the nitrogen - containing heterocyclic compounds, and they can be appropriately selected according to the purpose. Examples include nitrogen - containing heterocyclic compounds such as 2 - pyrrolidone, N - methyl - 2 - pyrrolidone, N - hydroxyethyl - 2 - pyrrolidone, 1,3 - dimethyl - 2 - imidazolidinone, ε - caprolactam, γ - butyrolactone, and the like.

[0065] There are no particular restrictions on the amides, and they can be appropriately selected according to the purpose. Examples include formamide, N - methylformamide, N,N - dimethylformamide, 3 - methoxy - N,N - dimethylpropionamide, 3 - butoxy - N,N - dimethylpropionamide, and the like.

[0066] There are no particular restrictions on the amines, and they can be appropriately selected according to the purpose. Examples include monoethanolamine, diethanolamine, triethylamine, and the like.

[0067] The sulfur-containing compound is not particularly limited and can be appropriately selected according to the purpose. For example, dimethyl sulfoxide, sulfolane, thiodiethanol, etc. can be mentioned.

[0068] The content of the organic solvent is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of excellent drying property, it is preferably 7.0% by mass or less, and more preferably 5.0% by mass or less.

[0069] The content of the water is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of the drying property and ejection reliability of the ink, it is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 60% by mass or less with respect to the total amount of the ink.

[0070] <Other components> The other components are not particularly limited and can be appropriately selected according to the purpose. For example, surfactants, colorants, defoamers, antiseptic and antifungal agents, rust preventives, pH adjusters, film-forming aids, etc. can be mentioned.

[0071] -Surfactant- The surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, anionic surfactants, etc. can be mentioned. These may be used alone or in combination of two or more.

[0072] As the silicone-based surfactant, those that do not decompose even at high pH are preferred. The silicone-based surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, silicone-based surfactants having a modified group such as polyether-modified silicone-based surfactants, side-chain modified polydimethylsiloxane, both-terminal modified polydimethylsiloxane, one-terminal modified polydimethylsiloxane, side-chain and both-terminal modified polydimethylsiloxane, etc. can be mentioned. These may be used alone or in combination of two or more.

[0073] The modified group is not particularly limited and can be appropriately selected according to the purpose. However, those having a polyoxyethylene group and a polyoxyethylene polyoxypropylene group are preferable because they exhibit good properties as an aqueous surfactant.

[0074] As the silicone-based surfactant, those synthesized as appropriate may be used, or commercially available products may be used. The commercially available products are not particularly limited and can be appropriately selected according to the purpose. For example, those available from BYK-Chemie Japan Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., etc. can be mentioned.

[0075] The polyether-modified silicone-based surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, compounds in which a polyalkylene oxide structure is introduced into the Si-side chain of dimethylsiloxane can be mentioned. The polyether-modified silicone-based surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, those in which a polyalkylene oxide structure represented by the following general formula (S-1) is introduced into the Si-side chain of dimethylpolysiloxane can be mentioned.

Chemical formula

[0076] As the polyether-modified silicone-based surfactant, commercially available products can be used. The commercially available products are not particularly limited and can be appropriately selected according to the purpose. For example, KF-618, KF-642, KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (manufactured by Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (manufactured by Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (manufactured by BYK-Chemie GmbH), TSF4440, TSF4452, TSF4453 (manufactured by Toshiba Silicone Co., Ltd.), etc. can be mentioned.

[0077] The fluorosurfactant is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of low foaming property, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferable. These may be used alone or in combination of two or more.

[0078] The perfluoroalkyl sulfonic acid compound is not particularly limited and can be appropriately selected according to the purpose. For example, perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, etc. can be mentioned.

[0079] The perfluoroalkyl carboxylic acid compound is not particularly limited and can be appropriately selected according to the purpose. For example, perfluoroalkyl carboxylic acid, perfluoroalkyl carboxylate, etc. can be mentioned.

[0080] The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is not particularly limited and can be appropriately selected according to the purpose. For example, a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, a salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and the like can be mentioned.

[0081] The counter ion of the salt in the fluorosurfactant is not particularly limited and can be appropriately selected according to the purpose. For example, Li, Na, K, NH 4 、NH 3 CH 2 CH 2 OH, NH 2 (CH 2 CH 2 OH) 2 、NH(CH 2 CH 2 OH) 3 and the like.

[0082] The fluorosurfactant is not particularly limited and can be appropriately selected according to the purpose. However, a compound having 2 to 16 carbon atoms substituted with fluorine is preferable, and a compound having 4 to 16 carbon atoms substituted with fluorine is more preferable. Examples of the fluorosurfactant include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain. Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferable because they have less foaming property, and fluorosurfactants represented by general formula (F-1) and general formula (F-2) are particularly preferable.

Chemical formula

Chemical formula

[0083] As the fluorosurfactant, commercially available products may be used. The commercially available products are not particularly limited and can be appropriately selected according to the purpose. For example, Surfron S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145 (all manufactured by Asahi Glass Co., Ltd.); Fluorad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F-1405, F-474 (all manufactured by Dainippon Ink and Chemicals, Incorporated); 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-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), Unidine DSN-403N (manufactured by Daikin Industries, Ltd.), etc. Among these, from the viewpoint of significantly improving good printing quality, particularly color development, penetrability, wettability, and leveling property with respect to paper, FS-3100, FS-34, FS-300 manufactured by Chemours, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omnova, and Unidine DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferred.

[0084] The amphoteric surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, etc. may be mentioned. These may be used alone or in combination of two or more.

[0085] The nonionic surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, ethylene oxide adduct of acetylene alcohol, etc. can be mentioned. These may be used alone or in combination of two or more. It is also okay.

[0086] The anionic surfactant is not particularly limited and can be appropriately selected according to the purpose. For example, polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, salt of polyoxyethylene alkyl ether sulfate, etc. can be mentioned. These may be used alone or in combination of two or more.

[0087] The content of the surfactant is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of excellent wettability and discharge stability and improved image quality, 0.001% by mass or more and 5% by mass or less is preferable, and 0.05% by mass or more and 5% by mass or less is more preferable.

[0088] -Colorant- The colorant is not particularly limited and can be appropriately selected according to the purpose. For example, pigments, dyes, etc. can be mentioned. Examples of the pigment include inorganic pigments, organic pigments, etc. These may be used alone or in combination of two or more. Also, mixed crystals may be used.

[0089] The pigment is not particularly limited and can be appropriately selected according to the purpose. For example, black pigment, yellow pigment, magenta pigment, cyan pigment, white pigment, green pigment, orange pigment, metallic pigments such as shiny pigments of gold and silver, etc. can be mentioned.

[0090] The inorganic pigment is not particularly limited and can be appropriately selected according to the purpose. For example, titanium oxide, iron oxide, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black produced by known methods such as the contact method, the furnace method, and the thermal method can be mentioned.

[0091] The organic pigment is not particularly limited and can be appropriately selected according to the purpose. For example, azo pigments, polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (for example, basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, aniline black, resin hollow particles, inorganic hollow particles, etc. can be mentioned. Among these, those with good affinity for the solvent are preferred.

[0092] Specific examples of the pigment include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black for black use, metals such as copper, iron (C.I. Pigment Black 11), and titanium oxide, and organic pigments such as aniline black (C.I. Pigment Black 1). Also, for color use, C.I. 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, C.I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 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 (vermilion), 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, C.I. Pigment Violet 1 (rhodamine lake), 3, 5:1, 16, 19, 23, 38, C.I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15:1, 15:2, 15:3, 15:4 (phthalocyanine blue), 16, 17:1, 56, 60, 63, C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. can be mentioned.

[0093] The pigment is preferably used by being dispersed in the ink. In order to obtain the ink by dispersing the pigment, methods such as introducing a hydrophilic functional group into the pigment to form a self-dispersing pigment, coating the surface of the pigment with a resin for dispersion, and using a dispersant for dispersion can be mentioned. As a method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersible pigment, for example, a method of making it dispersible in water by adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon) can be mentioned. As a method of coating and dispersing the surface of the pigment with a resin, a method of including the pigment in microcapsules to make it dispersible in water can be mentioned. This can be rephrased as a resin-coated pigment. In this case, not all of the pigments used need to be coated with resin, and uncoated pigments or partially coated pigments may be included. As a method of dispersing using the dispersant, methods of dispersing using known low-molecular-type dispersants and high-molecular-type dispersants represented by surfactants can be mentioned. As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used according to the pigment. RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalene sulfonate formalin condensate can also be suitably used as the dispersant. The dispersant may be used alone or in combination of two or more.

[0094] There is no particular limitation on the dye, and it can be appropriately selected according to the purpose. For example, acid dyes, direct dyes, reactive dyes, basic dyes, etc. can be mentioned. These may be used alone or in combination of two or more. Examples of the dye include C.I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. Acid Red 52, 80, 82, 249, 254, 289, C.I. Acid Blue 9, 45, 249, C.I. Acid Black 1, 2, 24, 94, C.I. Food Black 1, 2, C.I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. Direct Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. Reactive Red 14, 32, 55, 79, 249, C.I. Reactive Black 3, 4, 35, and the like.

[0095] The content of the coloring material is not particularly limited and can be appropriately selected according to the purpose. Preferably, it is 1.0% by mass or more and 15.0% by mass or less, more preferably 1.0% by mass or more and 10.0% by mass or less, based on the total amount of the ink.

[0096] The P99 in the particle size distribution of ISO Max Distance based on the number in the ink is not particularly limited and can be appropriately selected according to the purpose. Preferably, it is 9 μm or less. Thereby, the viscosity of the ink at 25°C at a shear rate of 5,000 S -1 can be more controlled. Further, when the P99 is 9 μm or less, when there is a flow path with a width of several tens of μm to several hundreds of μm in the flow path from when the ink is supplied in the printing apparatus until it is ejected from the nozzle, the flow of the ink in the flow path becomes smooth and the ejection stability can be improved.

[0097] The method for measuring P99 in the particle size distribution of ISO Max Distance is not particularly limited and can be appropriately selected according to the purpose. For example, it can be measured using an injection type image analysis particle size distribution meter IF-3200. Specifically, the ink is diluted with water so that the particles in the ink can be observed. Using an injection-type image analysis particle size distribution meter IF-3200, the particle size distribution of ISO Max Distance based on the number in the particles in the ink can be measured for P99 in the range of 0.1 μm to 100 μm. Since the dilution amount varies depending on the amount and size of the particle components in the ink, it is necessary to adjust the dilution ratio so that the individual particle sizes in the ink can be observed. If the ink aggregates in water, it may be diluted with a solvent in which the ink does not aggregate (for example, cyclohexane, etc.).

[0098] The glass transition temperature of the dry film of the ink (hereinafter, may be referred to as "coating film") is not particularly limited and can be appropriately selected according to the purpose, but is preferably 15 °C or lower. The method for measuring the glass transition temperature is not particularly limited and can be appropriately selected according to the purpose and can be measured using a differential scanning calorimeter (TA-60WS and DSC-60, manufactured by Shimadzu Corporation). Specifically, first, 4 g of the ink is placed in a petri dish made of tetrafluoroethylene·perfluoroalkyl vinyl ether copolymer (PFA) with a diameter of 50 mm so as to spread evenly, and dried at 50 °C for 1 week to obtain a dry film of the ink. 5.0 mg is taken from the obtained dry film of the ink and placed in an aluminum sample container. The sample container is placed on a holder unit and set in an electric furnace. Next, under a nitrogen atmosphere, the temperature is raised from 0 °C to 150 °C at a heating rate of 10 °C / min, and then, after cooling from 150 °C to -80 °C at a cooling rate of 5 °C / min, the temperature is further raised from -80 °C to 150 °C at a heating rate of 10 °C / min to measure the DSC curve. From the obtained DSC curve, using the analysis program in the DSC-60 system, the inflection point during the second heating is analyzed by the midpoint method to obtain the glass transition point (Tg).

[0099] The resin content in the dry film of the ink is not particularly limited and can be appropriately selected according to the purpose, but is preferably 10% by mass or more and 60% by mass or less. Note that the content represents the content of the solid component of the resin.

[0100] The content of the solid component in the ink is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of good drying property and excellent hiding property, 45% by mass or more is preferable, and 55% by mass or more is more preferable. The solid component refers to the solid components contained in the ink, and examples thereof include the thickening particles, resin, pigment, and the like.

[0101] The static surface tension of the ink is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of the ink being suitably leveled on the substrate and the drying time of the ink being shortened, at 25 °C, 35 mJ / m 2 The following is preferable, and 30 mJ / m 2 The following is more preferable.

[0102] The pH of the ink is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of preventing corrosion of the wetted metal members, 7 or more and 12 or less is preferable, and 8 or more and 11 or less is more preferable.

[0103] <Method for manufacturing ink> The method for manufacturing the ink is not particularly limited and can be appropriately selected according to the purpose. For example, it can be obtained by dispersing or dissolving the constituent components in an aqueous medium and further stirring and mixing as necessary. The stirring and mixing can be performed using, for example, a stirrer using ordinary stirring blades, a magnetic stirrer, a high-speed disperser, or the like.

[0104] (Printing method and printing apparatus)

[0105] The "inkjet printing apparatus" in this specification refers to a liquid ejection apparatus capable of ejecting the ink of the present invention, the treatment liquid, and the like onto an object to be printed.

[0106] Hereinafter, an example of a liquid ejection device as an inkjet printing device will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below. FIG. 6 is a schematic side view showing an example of a liquid ejection device as a printing device according to an embodiment of the present invention. FIG. 7 is a schematic plan view showing an example of a liquid ejection device as a printing device according to an embodiment of the present invention. The liquid ejection device 1000 is installed so as to face the object to be printed 100. The carriage C mounts a head 300 for ejecting ink, which is an example of a liquid, toward the object to be printed 100. And the Z-axis rail 103 holds the carriage C so that the carriage C can move in the Z-axis direction. The X-axis rail 101 holds the Z-axis rail 103 so that the Z-axis rail 103 holding the carriage C can move in the X-axis direction. Further, the Y-axis rail 102 holds the X-axis rail 101 so that the X-axis rail 101 can move in the Y-axis direction. Here, the X-axis is an example of the “first axis”, the Y-axis is an example of the “second axis intersecting the first axis”, and the Z-axis is an example of the “third axis intersecting the first axis and the second axis”. Also, the carriage C is an example of the “liquid ejection unit”, and the head 300 is an example of the “liquid ejection head”.

[0107] The liquid ejection device 1000 includes a Z-direction driving unit 92 that moves the carriage C in the Z-axis direction along the Z-axis rail 103, and an X-direction driving unit 72 that moves the Z-axis rail 103 in the X-axis direction along the X-axis rail 101. Further, the liquid ejection device 1000 includes a Y-direction driving unit 82 that moves the X-axis rail 101 in the Y-axis direction along the Y-axis rail 102. The Z-direction driving unit 92 is an example of the “first driving means” and moves the carriage C in the direction of the Z-axis intersecting the X-axis and the Y-axis. Note that the movement of the carriage C and the head 300 in the Z-axis direction does not have to be parallel to the Z-axis direction, and even if it is an oblique movement as long as it includes at least a component in the Z-axis direction is acceptable. The carriage C further includes another Z-direction driving unit 93. The Z-direction driving unit 93 is an example of the “second driving means” and moves the head 300 in the Z-axis direction with respect to the carriage C. The liquid ejection device 1000 configured as described above ejects ink from the head 300 toward the object to be drawn 100 while moving the carriage C in the directions of the X-axis, Y-axis, and Z-axis, and performs drawing on the object to be drawn 100. Note that although the object to be printed 100 is shown in the form of a flat plate, it may be a surface that is nearly vertical or has a large radius of curvature, such as an automobile, a truck, or an airplane.

[0108] <Substrate> The substrate (hereinafter, may be referred to as the "object to be printed") means an object to be printed using the ink of the present invention, and means an object to which ink or a treatment liquid can adhere even temporarily. There is no particular limitation on the substrate, and it can be appropriately selected according to the purpose. However, a road surface, an exterior, and a porous substrate are preferable. There is no particular limitation on the shape, structure, and material of the substrate, and it can be appropriately selected according to the purpose. For example, siding (ceramic-based, resin-based, wood-based, metal-based), asphalt, asphalt felt, concrete, glass, cloth, paper, plastic, wood, metal (brass, iron, aluminum, SUS (stainless steel) copper, etc.), or a non-metal substrate subjected to metal coating treatment by a method such as vapor deposition can be mentioned.

[0109] The porous substrate includes, for example, substrates with high ink permeability such as asphalt and sponge.

Example

[0110] Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples at all.

[0111] <Fabrication of Nozzle 1> The head for a Retalo robot (a head mounted on a Retalo robot, manufactured by Ricoh Digital Painting Co., Ltd.) was improved to have a nozzle diameter of 300 μm. Using Optool DSX (manufactured by Daikin Industries, Ltd.), a liquid-repellent layer containing fluorine with a film thickness of 0.01 μm was formed by the dipping method as shown in Fig. 3. At this time, the areas where the liquid-repellent layer containing fluorine was not formed were masked with a water-soluble resin or tape. After the liquid-repellent layer containing fluorine was applied and formed, it was peeled off and removed, and then heated at 120 °C for 1 hour to form the liquid-repellent layer containing fluorine, and nozzle 1 (nozzle diameter: 300 μm) was fabricated. Also, in the same manner, a layer containing fluorine with a film thickness of 0.01 μm was formed on a SUS plate, and the surface free energy was measured, and it was 13 mJ / m 2 It was. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0112] <Fabrication of Nozzle 2> Nozzle 2 (nozzle diameter: 300 μm) was fabricated in the same manner as the fabrication method of nozzle 1, except that a liquid-repellent layer containing fluorine with a film thickness of 0.01 μm was formed by the dipping method as shown in Fig. 2. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0113] <Fabrication of Nozzle 3> Nozzle 3 (nozzle diameter: 300 μm) was fabricated in the same manner as the fabrication method of nozzle 1, except that a liquid-repellent layer containing fluorine with a film thickness of 0.01 μm was formed by the dipping method as shown in Fig. 1. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0114] <Fabrication of Nozzle 4> Using DOWSIL SR2400 Resin (manufactured by Dow Corning Toray Co., Ltd.), about 1 mg / cm was applied by the dipping method. 2A liquid-repellent layer containing silicon was formed as shown in Fig. 3. At this time, the portions where the layer containing silicon was not formed were masked with a water-soluble resin or tape. After the liquid-repellent layer containing silicon was applied and formed, it was peeled off and removed, and then heat-cured at 150 °C for 2 hours to form a liquid-repellent layer containing silicon, and a nozzle 4 (nozzle diameter: 300 μm) was fabricated. Also, in the same manner, about 1 mg / cm 2 A liquid-repellent layer containing silicon was formed and the surface free energy was measured, and it was 22 mJ / m 2 . The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0115] <Fabrication of Nozzle 5> A nozzle 5 (nozzle diameter: 300 μm) was fabricated in the same manner as the fabrication method of nozzle 4, except that a liquid-repellent layer containing silicon was formed by the dipping method to adhere about 1 mg / cm 2 . The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0116] <Fabrication of Nozzle 6> A nozzle 5 (nozzle diameter: 300 μm) was fabricated in the same manner as the fabrication method of nozzle 4, except that a liquid-repellent layer containing silicon was formed by the dipping method to adhere about 1 mg / cm 2 . The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0117] <Fabrication of Nozzle 7> A nozzle 7 (nozzle diameter: 50 μm) was fabricated in the same manner as the fabrication method of nozzle 1, except that the nozzle diameter was 50 μm. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0118] <Fabrication of Nozzle 8> A nozzle 8 (nozzle diameter: 600 μm) was fabricated in the same manner as the fabrication method of nozzle 1, except that the nozzle diameter was 600 μm. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0119] <Fabrication of Nozzle 9> A nozzle 9 (nozzle diameter: 900 μm) was fabricated in the same manner as the fabrication method of nozzle 1, except that the nozzle diameter was 900 μm. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0120] <Fabrication of Nozzle 10> Using Chemite CT4112 (manufactured by Kyocera Chemical Corporation) mainly composed of polyamic acid, which is a precursor of polyimide, a liquid-repellent layer of polyimide with a film thickness of 0.3 μm was formed by the dipping method as shown in Figure 3. At this time, the parts where the polyimide layer was not to be formed were masked with a water-soluble resin, tape, etc., and after the liquid-repellent layer of polyimide was coated and formed, it was peeled off and removed. After gradually heating to 110 °C and heating for 60 minutes, it was heated at 200 °C for 20 minutes, and further heated stepwise to 360 °C and heated for 60 minutes to form a polyimide layer, and nozzle 10 (nozzle diameter: 300 μm) was fabricated. Also, in the same manner, a liquid-repellent layer of polyimide with a film thickness of 0.3 μm was formed on a SUS plate, and when the surface free energy was measured, it was 50 mJ / m 2 It was. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0121] <Fabrication of Nozzle 11> A nozzle 11 (nozzle diameter: 300 μm) was fabricated in the same manner as the fabrication method of nozzle 10, except that the liquid-repellent layer was formed as shown in Figure 2. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0122] <Fabrication of Nozzle 12> A nozzle 12 (nozzle diameter: 300 μm) was fabricated in the same manner as the fabrication method of nozzle 10, except that a liquid-repellent layer was formed as shown in Fig. 1. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0123] <Fabrication of Nozzle 13> A head 13 (nozzle diameter: 300 μm) having a substrate made of SUS that does not form a liquid-repellent layer, a nozzle hole, a liquid chamber, and a needle valve was fabricated. When the surface free energy of the SUS was measured, it was 33 mJ / m 2 It was. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0124] <Fabrication of Nozzle 14> A head 14 (nozzle diameter: 300 μm) having a substrate made of SUS, a nozzle hole, a liquid chamber, and a needle valve with its tip covered with a perfluoroelastomer having a thickness of 200 μm as shown in Fig. 8 was fabricated. The shape of the fabricated nozzle, the compound contained in the water-repellent layer, the surface free energy of the water-repellent layer, and the nozzle diameter are shown in Table 1.

[0125]

Table 1

[0126] <Preparation of White Pigment Dispersion> A mixture of 200 parts by mass of C.I. Pigment White 6 (manufactured by Teika Co., product name "JR-403", number-average primary particle diameter 250 nm, aspect ratio 2, surface treatment: Al, Si) as a pigment, 56 parts by mass of a pigment dispersant (trade name: TEGO Dispers 651, manufactured by Evonik Industries AG), and 744 parts by mass of distilled water was premixed. Then, using a bead mill disperser (manufactured by Kotobuki Industries Co., Ltd., UAM-015), zirconia beads with a diameter of 0.03 mm (density 6.03×10-6 g / m 2 ) After being dispersed at a peripheral speed of 10 m / s and a liquid temperature of 30 °C for 15 minutes, coarse particles were centrifuged using a centrifuge (manufactured by Kubota Corporation, Model-3600) to obtain a white pigment dispersion with an average particle diameter of 250 nm (solid content: 20.0 mass%).

[0127] <Preparation of Cyan Pigment Dispersion> In the reaction vessel of an automatic polymerization reactor (manufactured by Hou Industries Co., Ltd.: Polymerization Tester DSL-2AS type) equipped with a reaction vessel having a stirring device, a dropping device, a temperature sensor, and a reflux device with a nitrogen introduction device at the top, 550 g of methyl ethyl ketone was charged, and the inside of the reaction vessel was purged with nitrogen while stirring. Thereafter, while maintaining the inside of the reaction vessel in a nitrogen atmosphere, it was heated to 80 °C, and then a mixed solution of 75.0 g of 2-hydroxyethyl methacrylate, 77.0 g of methacrylic acid, 80.0 g of styrene, 150.0 g of butyl methacrylate, 98.0 g of butyl acrylate, 20.0 g of methyl methacrylate, and 40.0 g of "Perbutyl (registered trademark) O" (manufactured by NOF Corporation) was dropped over 4 hours using the dropping device. After completion of the dropping, the reaction was continued at the same temperature for 15 hours to obtain a methyl ethyl ketone solution of an anionic group-containing styrene-acrylic copolymer having an acid value of 100, a weight average molecular weight of 21,000, and a Tg (calculated value) of 31 °C. After completion of the reaction, a part of the methyl ethyl ketone was distilled off under reduced pressure to obtain a copolymer solution having the non-volatile content adjusted to 50%. In a mixing tank equipped with a cooling jacket, 1,000 g of copper phthalocyanine (manufactured by Dainichi Seika Kogyo Co., Ltd., SEIKALIGHT BLUE A612), 800 g of the copolymer solution, 143 g of a 10% aqueous sodium hydroxide solution, 100 g of methyl ethyl ketone, and 1,957 g of water were charged and stirred and mixed to obtain a mixed solution. The obtained mixed solution was passed through a dispersion device (manufactured by Mitsui Mining Co., Ltd.: SC Mill SC100) filled with zirconia beads having a diameter of 0.3 mm, and dispersed under the conditions of a rotation speed of 2,700 revolutions per minute, 40 °C or lower (maintained at a constant temperature by passing cold water through the cooling jacket), and 6 hours by a circulation method (a method of returning the dispersion liquid discharged from the dispersion device to the mixing tank). After the dispersion was completed, the dispersion stock solution was withdrawn from the mixing tank. Subsequently, the mixing tank and the dispersion apparatus flow path were washed with 10,000 g of water, and a diluted dispersion was obtained by combining it with the dispersion stock solution. The obtained diluted dispersion was placed in a glass distillation apparatus, and the entire amount of methyl ethyl ketone and a part of the water were distilled off. After cooling to room temperature, 10% hydrochloric acid was added dropwise while stirring to adjust the pH to 4.5. Then, the solid content was filtered with a Nutsche filter (manufactured by Nippon Kagaku Kikai Seizo Co., Ltd., pressure filter) and washed with water. The cake was placed in a container, 200 g of a 20% aqueous potassium hydroxide solution was added, and it was dispersed with a Dispa (manufactured by Tokushu Kika Kogyo Co., Ltd., TK homodisper), and further water was added to adjust the nonvolatile content. As a result, a cyan pigment dispersion (pigment content concentration: 20.0% by mass) containing composite particles (pigment-containing matter) in which copper phthalocyanine was coated with a carboxyl group-containing styrene-acrylic copolymer neutralized in potassium hydroxide was obtained.

[0128] <Preparation of resin emulsion> A mixture of 55.4 parts by mass of methyl methacrylate as a monomer, 44.6 parts by mass of 2-ethylhexyl acrylate, 1.5 parts by mass of Aqualon KH-20 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as an emulsifier, and 53.1 parts by mass of ion-exchanged water was emulsified with a batch-type homomixer to prepare a monomer pre-emulsion. 89.4 parts by mass of ion-exchanged water was placed in a 2 L four-necked flask equipped with a stirrer, a nitrogen inlet tube, a reflux condenser, a thermometer, and a raw material inlet. While introducing nitrogen, the liquid temperature was warmed to 60 °C while stirring. 0.5 part by mass of Aqualon KH-20 as an emulsifier and 6 parts by mass of a 5% aqueous ammonium persulfate solution (0.3 part by mass of ammonium persulfate) were added to the reaction vessel. Then, 10 minutes after adding the 5% aqueous ammonium persulfate solution to the reaction vessel, the monomer pre-emulsion was continuously dropped from the dropping tank over 5 hours, and 6 parts of a 5% aqueous ammonium persulfate solution (0.3 part as ammonium persulfate) was intermittently dropped from another dropping tank at 70 °C over 5 hours. After the dropping was completed, aging was carried out while maintaining the temperature at 70 °C for 3 hours. It was then cooled to 50°C, aqueous ammonia was added, and it was filtered through a polyester filter cloth of 180 mesh to obtain resin emulsion A. A part of the obtained resin emulsion A was dried at 150°C for 30 minutes, and when the solid content concentration was measured in accordance with JIS K5601-1-2, it was 50.0%. Also, when the glass transition point of resin emulsion A was measured by the following method, it was 0°C.

[0129] <Measurement of the glass transition point (Tg) of the resin emulsion> Specifically, 4 g of the resin emulsion was placed in a 50-mm-diameter petri dish made of tetrafluoroethylene·perfluoroalkyl vinyl ether copolymer (PFA) so as to spread uniformly, and it was dried at 50°C for 1 week to obtain a resin film. 5.0 mg was taken from the obtained resin film and placed in an aluminum sample container, and the sample container was placed on a holder unit and set in an electric furnace. Next, under a nitrogen atmosphere, the temperature was raised from 0°C at a rate of 10°C / min to 150°C, and then, after the temperature was lowered from 150°C at a rate of 5°C / min to -80°C, the temperature was further raised from -80°C at a rate of 10°C / min to 150°C to measure a DSC curve. From the obtained DSC curve, using the analysis program in the DSC-60 system, the inflection point during the second heating was analyzed by the midpoint method to obtain the glass transition point (Tg).

[0130] <Preparation of Ink 1> 5.0 mass% of propylene glycol as a solvent, 9.0 mass% of ion-exchanged water, 30.0 mass% of the resin emulsion A as a resin, and 20.0 mass% of a white pigment dispersion as a colorant were mixed and stirred for 30 minutes to be uniform, and 36.0 mass% of calcium carbonate (UP-G, manufactured by Imerys Specialties Japan Co., Ltd.) as thickening particles was added, and it was further stirred at high speed for 1 hour to be uniform to obtain Ink 1.

[0131] <Preparation of Ink 2> 5.0% by mass of propylene glycol as a solvent, 2.0% by mass of ion-exchanged water, 33.0% by mass of the resin emulsion A as a resin, and 20.0% by mass of a white pigment dispersion as a colorant were mixed and stirred for 30 minutes to make them uniform. 40.0% by mass of calcium carbonate (UP-G, manufactured by Imerys Specialties Japan Co., Ltd.) as thickening particles was added, and the mixture was further stirred at high speed for 1 hour to make it uniform, thereby obtaining Ink 2.

[0132] <Preparation of Ink 3> 5.0% by mass of propylene glycol as a solvent, 20.0% by mass of ion-exchanged water, 35.0% by mass of the resin emulsion A as a resin, and 20.0% by mass of a white pigment dispersion as a colorant were mixed and stirred for 30 minutes to make them uniform. 20.0% by mass of calcium carbonate (UP-G, manufactured by Imerys Specialties Japan Co., Ltd.) as thickening particles was added, and the mixture was further stirred at high speed for 1 hour to make it uniform, thereby obtaining Ink 3.

[0133] <Preparation of Ink 4> 14.0% by mass of ion-exchanged water as a solvent, 30.0% by mass of the resin emulsion A as a resin, and 20.0% by mass of a white pigment dispersion as a colorant were mixed and stirred for 30 minutes to make them uniform. 36.0% by mass of calcium carbonate (UP-G, manufactured by Imerys Specialties Japan Co., Ltd.) as thickening particles was added, and the mixture was further stirred at high speed for 1 hour to make it uniform, thereby obtaining Ink 4.

[0134] <Preparation of Ink 5> 4.0% by mass of propylene glycol and 10.0% by mass of ion-exchanged water as a solvent, 30.0% by mass of the resin emulsion A as a resin, and 20.0% by mass of a cyan pigment dispersion as a colorant were mixed and stirred for 30 minutes to make them uniform. 36.0% by mass of calcium carbonate (UP-G, manufactured by Imerys Specialties Japan Co., Ltd.) as thickening particles was added, and the mixture was further stirred at high speed for 1 hour to make it uniform, thereby obtaining Ink 5.

[0135] <Viscosity of Ink> The viscosity of the ink was measured using an MCR301 (manufactured by Anton Parr) with a cone plate (cone radius: 25 mm, cone angle: 1°) at a shear rate of 1 S -1 at 25°C for the viscosity (mPa·s), and at a shear rate of 5,000 S -1 at 25°C for the viscosity (mPa·s), and at a shear rate of 0.1 S -1 at 25°C for the viscosity (mPa·s). The viscosities of Inks 1 to 5 were as shown in Table 1. Note that the unit of each number in the composition in Table 1 indicates "mass %".

[0136]

Table 2

[0137] (Example 1) The following "discharge stability after no capping" was evaluated for the combination of Nozzle 1 and Ink 1. The results are shown in Table 2.

[0138] <Discharge stability after no capping> The ink was set in various heads, and after initial discharging for 3 min, the nozzle was left uncapped and exposed to the atmosphere for 10 min and 20 min, and then the discharging evaluation was performed again for 3 min. The discharge stability was evaluated based on the following evaluation criteria. A discharge stability evaluation result of "C" or higher is within the practical range. [Evaluation criteria] A: No bending, shaking, etc. of the discharge occurs, and stable discharge can be achieved B: Slight bending, shaking, etc. of the discharge may occur, but stable discharge can be achieved C: Bending, shaking, etc. of the discharge may occur, but the degree of bending and shaking is within the allowable range D: Bending, shaking, etc. of the discharge may occur, and stable discharge cannot be achieved or discharge is impossible

[0139] (Examples 2 to 13 and Comparative Examples 1 to 5) Using the combination of the nozzle and the ink described in Table 2, the "discharge stability after no capping" of Example 1 was evaluated. The results are shown in Table 2.

[0140]

Table 3

[0141] As aspects of the present invention, for example, they are as follows. <1> A liquid discharge unit having a nozzle portion for discharging a high-viscosity liquid, wherein the nozzle portion includes a nozzle hole, a nozzle plate having the nozzle hole, a liquid chamber for supplying liquid to the nozzle hole, and a needle valve that closes or opens the nozzle hole at the tip while making a reciprocating motion in the liquid chamber. <1> A liquid discharge unit, characterized in that a liquid-repellent layer having a surface free energy of less than 29 mJ / m 2 is provided on the surface of the nozzle plate. <2> The liquid discharge unit according to <1>, wherein the liquid-repellent layer is provided on the outer surface and the nozzle hole forming surface of the nozzle plate. <3> The liquid discharge unit according to <1> or <2>, wherein the liquid-repellent layer is provided on the inner surface of the nozzle plate. <4> The liquid discharge unit according to any one of <1> to <3>, wherein the liquid-repellent layer is provided at the tip of the needle valve. <5> The liquid discharge unit according to any one of <1> to <4>, wherein the liquid-repellent layer contains at least one of silicon (Si) and fluorine (F). <6> The liquid discharge unit according to <5>, wherein the liquid-repellent layer contains at least one of a fluorine-modified hydrocarbon and an organosilicon compound. <7> The liquid discharge unit according to <5>, wherein the liquid-repellent layer contains a fluorine-modified hydrocarbon in which silanol groups are condensed and bonded. <8> The liquid discharge unit according to <5>, wherein the liquid-repellent layer contains a siloxane polymer having a siloxane bond as a main chain and an organic group as a side chain. <9> The liquid discharge unit according to any one of <1> to <8>, wherein the diameter of the nozzle hole is 50 μm or more. A printing apparatus having ejection means for ejecting liquid from the liquid ejection unit according to any one of <1> to <9>. <11> The printing apparatus according to <10>, wherein the solid content of the liquid is 45% by mass or more. <12> The printing apparatus according to <10> or <11>, wherein the liquid is ink or paint. <13> A printing method characterized by having an ejection step of ejecting a high-viscosity liquid from the liquid ejection unit according to any one of <1> to <9>.

Explanation of Signs

[0142] 1 Substrate 2 Nozzle hole 3 Nozzle plate 4 Liquid chamber 5 Needle valve 6 Ink output passage 7 Elastomeric diaphragm 8 Movable iron core 9 Drive mechanism housing space 10 Spring material 11 Fixed iron core 12 Solenoid 13 Pressurization passage 14 Spring for preventing looseness of screw 15 Bolt for gap adjustment 16 Nut 17 Ink tank 18 Pump 20 Circulation path 21 Liquid-repellent layer C Carriage 72 X-direction drive unit 82 Y-direction drive unit 92 Z-direction drive unit 93 Z-direction drive unit 100 Object to be printed 101 X-axis rail 102 Y-axis rail 103 Z-axis rail 300 Head 1000 Liquid ejection device

Prior Art Documents

Patent Documents

[0143] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022-64482

Claims

1. A liquid discharge unit having a nozzle unit for discharging a high-viscosity liquid, wherein the nozzle unit includes a nozzle hole, a nozzle plate having the nozzle hole, a liquid chamber for supplying liquid to the nozzle hole, and a needle valve that closes or opens the nozzle hole at its tip while making a reciprocating motion within the liquid chamber. On the surface of the nozzle plate, there is a liquid-repellent layer with a surface free energy of less than 29 mJ / m ２ The liquid ejection unit is characterized by having a liquid-repellent layer with a surface free energy of less than 29 mJ / m

2. The liquid discharge unit according to claim 1, wherein a liquid-repellent layer is provided on an outer surface and a nozzle hole forming surface of the nozzle plate.

3. The liquid discharge unit according to claim 1 or 2, wherein a liquid-repellent layer is provided on an inner surface of the nozzle plate.

4. The liquid discharge unit according to claim 1 or 2, wherein a liquid-repellent layer is provided at the tip of the needle valve.

5. The liquid discharge unit according to claim 1 or 2, wherein the liquid-repellent layer contains at least one of silicon (Si) and fluorine (F).

6. The liquid discharge unit according to claim 5, wherein the liquid-repellent layer contains at least one of a fluorine-modified hydrocarbon and an organosilicon compound.

7. The liquid discharge unit according to claim 5, wherein the liquid-repellent layer contains a fluorine-modified hydrocarbon in which silanol groups are condensation-bonded.

8. The liquid discharge unit according to claim 5, wherein the liquid-repellent layer contains a siloxane polymer having a siloxane bond as a main chain and an organic group as a side chain.

9. The liquid discharge unit according to claim 1 or 2, wherein the diameter of the nozzle hole is 50 μm or more.

10. A printing apparatus having a discharge means for discharging liquid from the liquid discharge unit according to claim 1 or 2.

11. The printing apparatus according to claim 10, wherein the solid content of the liquid is 45% by mass or more.

12. The printing apparatus according to claim 10, wherein the liquid is ink or paint.

13. A printing method characterized by having a discharge step of discharging a high-viscosity liquid from the liquid discharge unit according to claim 1 or 2.

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