Nozzle plate, liquid dispensing head, image forming apparatus

Abstract

The objective of this invention is to improve the durability of the nozzle plate surface. [Solution] A nozzle plate 200 equipped with a nozzle 104 for discharging liquid, wherein a base material 201 on which the nozzle 104 is formed, a first film 202, a second film 203, and a water-repellent film 204 are formed in this order from the upstream side to the downstream side in the direction of liquid discharge from the nozzle 104, the first film 202 contains at least one of W, Mo, Ti, and Si and at least one of C, N, and O, and the second film 203 is an oxide film containing Si.

Description

Technical Field

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[0001] The present invention relates to a nozzle plate, a liquid ejection head, and an image forming apparatus.

Background Art

[0002] In a nozzle plate provided on a liquid ejection head, a water-repellent film is provided on the surface of the nozzle plate in order to improve the wiping property of droplets by a wiping member during maintenance.

[0003] In addition, the surface of the nozzle plate with this water-repellent film needs to have durability against deterioration of water repellency due to physical wear and scratches caused by repeated wiping operations of the wiping member, and chemical deterioration due to alkaline ink (liquid).

[0004] For example, in the nozzle plate of Patent Document 1 (WO2022 / 044245), a substrate adhesion layer containing Cr, an underlayer containing an inorganic oxide or an oxide containing carbon, and a water-repellent layer containing a coupling agent having fluorine on the outermost layer are provided on a substrate.

[0005] <00​​​​​​​​​​​​​​The objective of this invention is to improve the durability of the nozzle plate surface. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a nozzle plate equipped with a nozzle for discharging liquid, wherein, in the direction from upstream to downstream in the liquid discharge direction from the nozzle, a substrate on which the nozzle is formed, a first film, a second film, and a water-repellent film are formed in this order, the first film contains at least one of W, Mo, Ti, and Si, and at least one of C, N, and O, and the second film is an oxide film containing Si. [Effects of the Invention]

[0009] According to the present invention, the durability of the nozzle plate surface can be improved. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic side view illustrating the overall configuration of an image forming apparatus according to the first embodiment of the present invention. [Figure 2] Figure 1 is a plan view illustrating the area around the carriage of the image forming apparatus shown. [Figure 3] This is a cross-sectional diagram illustrating the liquid discharge head along the longitudinal direction of the liquid chamber. [Figure 4] Figure 3 is a cross-sectional diagram illustrating the liquid discharge head in the short-side direction of the liquid chamber (direction of nozzle arrangement). [Figure 5] This figure shows the configuration of a nozzle plate according to one embodiment of the present invention. [Figure 6] This diagram shows the relationship between the film thickness of the first film and the contact angle with the ink. [Figure 7] This figure shows the results of measuring the contact angle before and after the wiping operation in the examples and comparative examples. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be simplified or omitted as appropriate.

[0012] First, an image forming apparatus according to the first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic side view illustrating the overall configuration of the image forming apparatus according to the first embodiment of the present invention, and Figure 2 is a plan view illustrating the area around the carriage of the image forming apparatus shown in Figure 1.

[0013] This image forming apparatus is a serial inkjet recording apparatus. The image forming apparatus 1 shown in Figures 1 and 2 mainly comprises an image forming unit 11, a paper feeding unit 12, a transport unit 13, a paper discharge unit 14, a maintenance and recovery mechanism 81, and the like.

[0014] As shown in Figure 2, in the image forming unit 11, side plates 21A and 21B are arranged on the left and right sides of the image forming apparatus 1. Guide rods 31 and 32 are horizontally mounted on the side plates 21A and 21B. The carriage 33 is held slidably in the main scanning direction A by the guide rods 31 and 32. The carriage 33 moves and scans in the carriage main scanning direction A, indicated by the arrow in Figure 2, via a timing belt by the main scanning motor.

[0015] This carriage 33 has recording heads 34a and 34b (referred to as "recording head 34" when not distinguished) which consist of multiple liquid ejection heads that eject yellow (Y), magenta (M), cyan (C), and black (K) inks. Each recording head 34a and 34b has a nozzle row consisting of multiple nozzles that eject liquid ink, arranged in a sub-scanning direction perpendicular to the main scanning direction. This carriage 33 is mounted so that the ink ejection direction of the nozzle row faces downward.

[0016] Each recording head 34 has two nozzle rows. One nozzle row of recording head 34a ejects black (K) ink, and the other nozzle row ejects cyan (C) ink. One nozzle row of recording head 34b ejects magenta (M) ink, and the other nozzle row ejects yellow (Y) ink. Alternatively, a recording head may be used that has nozzle rows for each color, with multiple nozzles arranged on a single nozzle surface.

[0017] The carriage 33 is equipped with sub-tanks 35a and 35b that supply ink of each color corresponding to the nozzle rows of the recording head 34. Ink (recording fluid) of each color is replenished and supplied to these sub-tanks 35 via supply tubes 36 for each color by the supply pump unit 24 from ink cartridges (main tanks) 10y, 10m, 10c, and 10k, which are detachably mounted in the cartridge loading section 4.

[0018] Referring to Figure 1, the paper feeding unit 12 includes a paper feeding tray 2 having a paper stacking section 41, a paper feeding roller 43, a separation pad 44, a guide member 45, a counter roller 46, a transport guide 47, and a pressing member 48 having a front pressure roller 49. With the separation pad 44, which is made of a material with a high coefficient of friction and faces the paper feeding roller 43, biased toward the paper feeding roller 43, the paper S is separated and fed one sheet at a time from the paper stacking section 41. The paper S fed from the paper feeding tray 2 is then guided by the guide member 45 and fed to the underside of the recording head 34 by the counter roller 46, the transport guide 47, and the pressing member 48 having a front pressure roller 49.

[0019] The transport unit 13 also includes a transport belt 51, transport rollers 52, and tension rollers 53. The transport belt 51 electrostatically attracts the fed paper S and transports it to a position facing the recording head 34. The transport belt 51 is an endless belt and is stretched between the transport rollers 52 and the tension rollers 53. The transport rollers 52 are rotated at the right timing by the sub-scanning motor, causing the transport belt 51 to move in a circular motion in the belt transport direction (sub-scanning direction) B shown in Figure 2.

[0020] Also, as a charging means for charging the surface of the conveyor belt 51, a charging roller 56 is disposed. This charging roller 56 is arranged to contact the surface layer of the conveyor belt 51 and rotate following the rotation of the conveyor belt 51.

[0021] Furthermore, as a paper discharging unit 14 for discharging the paper S recorded by the recording head 34, it includes a separating claw 61 for separating the paper S from the conveyor belt 51, a paper discharging roller 62, and a platen 63 which is a paper discharging roller. A paper discharge tray 3 is provided below the paper discharging roller 62.

[0022] Also, a duplex unit 71 is detachably attached to the back surface portion of the apparatus main body of the image forming apparatus 1. This duplex unit 71 takes in the paper S returned by the reverse rotation of the conveyor belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyor belt 51. Also, the upper surface of this duplex unit 71 serves as a manual feed tray 72.

[0023] Furthermore, in a non-printing area on one side in the scanning direction of the carriage 33, a maintenance and recovery mechanism 81 for maintaining and recovering the state of the nozzles of the recording head 34 is arranged. This maintenance and recovery mechanism 81 includes cap 82a, 82b, a wiper blade 83 as a wiping member, an air discharge receiver 84, a carriage lock 87, and the like. Caps 82a, 82b cap the respective nozzle surfaces of the recording heads 34a, 34b. The wiper blade 83 wipes the nozzle surface. The air discharge receiver 84 receives the ink due to the air discharge. This air discharge is an operation of discharging the ink that does not contribute to recording in order to discharge the thickened ink. The carriage lock 87 fixes the position of the carriage 33. Below the maintenance and recovery mechanism 81 of this head, a waste liquid tank 100 for storing the waste liquid generated by the maintenance and recovery operation is detachably attached to the apparatus main body.

[0024] Also, an air discharge receiver 88 is arranged in a non-printing area on the other side in the scanning direction of the carriage 33. This air discharge receiver 88 has an opening 89 along the nozzle row direction of the recording head 34.

[0025] The printing operation of this image forming apparatus configured in this way will now be explained. Paper S, which is fed one sheet at a time from the paper tray 2 and fed approximately vertically upward, is guided by the guide member 45 and transported between the transport belt 51 and the counter roller 46, and its leading edge is further guided by the transport guide 47. After that, it is pressed against the transport belt 51 by the leading edge pressure roller 49, and the transport direction is changed by approximately 90°.

[0026] At this time, a voltage is applied to the charging roller 56 such that positive and negative outputs alternately occur, and the charging roller 56 charges the transport belt 51 using a charging voltage pattern caused by an alternating current. When paper S is fed onto this charged transport belt 51, the paper S is attracted to the transport belt 51, and the paper S is transported in the sub-scanning direction by the circumferential movement of the transport belt 51.

[0027] Therefore, by moving the carriage 33 and driving the recording head 34 in accordance with the image signal, the carriage 33 is moved to a position above the transport belt 51, and ink is ejected onto the stationary paper S to form one line of image. After a predetermined amount of paper S has been transported by the transport belt 51, the carriage 33 forms the image for the next line. Upon receiving an image formation completion signal or a signal that the trailing edge of the paper S has reached the recording area, the image formation operation of the carriage 33 is terminated, and the paper S is ejected into the output tray 3.

[0028] Then, when maintaining and restoring the nozzles of the recording head 34, the carriage 33 is moved to a position opposite the maintenance and restoration mechanism 81, which is the home position. The maintenance and restoration mechanism 81 performs maintenance and restoration operations such as nozzle suction, which involves capping with caps 82a and 82b to draw ink from the nozzles, and dry ejection. Through these operations, stable ink ejection enables image formation.

[0029] In an image forming apparatus comprising such an inkjet recording device, a liquid ejection device implementing the present invention, as described below, is installed, enabling high-speed recording of high-quality images on plain paper using high-viscosity ink.

[0030] Next, an example of the internal configuration of the recording head (liquid ejection head) will be explained with reference to Figures 3 and 4. Figure 3 is a cross-sectional diagram of the liquid ejection head along the longitudinal direction of the liquid chamber, and Figure 4 is a cross-sectional diagram of the liquid ejection head of Figure 3 along the short direction of the liquid chamber (direction of nozzle arrangement).

[0031] In this liquid ejection head (recording head) 34, a flow channel plate 101, a diaphragm 102 joined to the lower surface of the flow channel plate 101, and a nozzle plate 200 joined to the upper surface of the flow channel plate 101 are joined and stacked. These together form a nozzle 104 for ejecting ink droplets, a nozzle communication passage 105, a pressurized liquid chamber (ink chamber) 106 which is a pressure generating chamber, a fluid resistance section 107, a common liquid chamber 108, an ink supply passage 109, and so on.

[0032] The ink in the pressurized liquid chamber 106 is discharged from the nozzle 104 through the nozzle communication passage 105, which is a flow path that communicates with the nozzle. Subsequently, as ink discharge ends, the ink pressure in the pressurized liquid chamber 106 decreases, and negative pressure is generated in the pressurized liquid chamber 106 due to the inertia of the ink flow and the discharge process of the drive pulse, leading to the ink filling process. At this time, the ink supplied from the ink tank (sub-tank) 35 flows into the common liquid chamber 108, and from the common liquid chamber 108 through the ink supply passage 109 and the fluid resistance section 107 to fill the pressurized liquid chamber 106.

[0033] Furthermore, the liquid discharge head is a pressure generating means (actuator) that deforms the diaphragm 102 to pressurize the ink in the pressurized liquid chamber 106, and is equipped with two stacked piezoelectric members 121 (only one row is shown in Figure 3) that function as electromechanical conversion elements.

[0034] Furthermore, the piezoelectric member 121 is joined and fixed to a base substrate 122 which, together with the piezoelectric member 121 and other components, constitutes an actuator unit. In this piezoelectric member 121, multiple piezoelectric elements 121A and support members 121B are formed by creating grooves using a non-divided slitting process. In this example, the piezoelectric elements 121A are driven piezoelectric element columns to which a drive waveform is applied, and the support members 121B are non-driven piezoelectric element columns to which a drive waveform is not applied.

[0035] The end electrode on one end face of the piezoelectric element 121 is divided by dicing using a half-cut process to form comb-shaped individual electrodes 154, while the end electrode on the other end face is not divided by processing such as notches and forms a common electrode 153 that conducts through all piezoelectric elements 121A. The common electrode 153 is connected to the ground (GND) electrode of the FPC cable 126 by wrapping an electrode layer around the end of the piezoelectric element 121A. A head driver (driver IC) is mounted on the FPC cable 126 and controls the application of a drive voltage to the common electrode 153 of the piezoelectric element 121A.

[0036] The peripheral edge of the diaphragm 102 is joined to the frame member 130. The frame member 130 has a through-hole 131 for housing the actuator unit consisting of the piezoelectric member 121 and the base substrate 122, a recess that functions as a common liquid chamber 108, and an ink supply hole 132 which is a supply port for supplying ink to the common liquid chamber 108 from the outside.

[0037] In the flow channel plate 101, grooves that will become the ink supply path 109, the fluid resistance section 107, the pressurized liquid chamber 106, and through-holes that will become the nozzle communication passage 105 relative to the nozzle 104 are formed by etching using a silicon single crystal substrate. The portion remaining after etching becomes the partition wall 110 of the pressurized liquid chamber 106. In addition, the liquid discharge head 34 is provided with a portion where the etching width is narrowed, and this portion becomes the fluid resistance section 107.

[0038] The diaphragm 102 has a thin-walled section (diaphragm section) 102-2 with a thickness of 2 to 10 μm to facilitate deformation in the portion corresponding to the pressurized liquid chamber 106, and a thick-walled section (island-shaped protrusion) 102-1A that is joined to the piezoelectric element 121A. The common electrode (movable part) 153 of the island-shaped protrusion 102-1A of the diaphragm 102 and the piezoelectric element 121A, and the connection between the diaphragm 102 and the frame member 130 are bonded by patterning an adhesive layer 123 containing a gap material. Here, the diaphragm 102 is formed from nickel electroformed in a two-layer structure. In this case, the thickness of the diaphragm section 102-2 is 3 μm, and the width is 35 μm (on one side).

[0039] The nozzle plate 200 forms nozzles 104 with a diameter of approximately 10 to 30 μm, corresponding to each pressurized liquid chamber 106, and is adhesively bonded to the flow channel plate 101. This nozzle plate 200 is made of materials such as metal (SUS), ceramic, Si, or resin, and a water-repellent film is formed on the outermost surface via a required film on the surface of the nozzle-forming member (details will be described later).

[0040] The piezoelectric member 121 is constructed by alternately stacking lead zirconate titanate (PZT) piezoelectric material 151 with a thickness of 10 to 50 μm per layer and internal electrodes 152 made of silver-palladium (AgPd) with a thickness of several μm per layer. The internal electrodes 152 are electrically connected alternately to individual electrodes 154 and common electrodes 153, which are end-face electrodes (external electrodes) at their ends.

[0041] In such a liquid ejection head 34, the drive piezoelectric element 121A contracts when the voltage applied to the piezoelectric element 121A is lowered from the reference potential Ve (for example, by applying a pulse voltage of 10-50V) based on the drive voltage generated by the head driver 210. As a result, the diaphragm 102 descends and the volume of the pressurized liquid chamber 106 expands, causing ink to flow into the pressurized liquid chamber 106.

[0042] Subsequently, the voltage applied to the piezoelectric element 121A is increased, causing the piezoelectric element 121A, which is the driving piezoelectric element column, to extend in the stacking direction. This deforms the diaphragm 102 toward the nozzle 104, thereby contracting the volume of the pressurized liquid chamber 106. This action pressurizes the ink in the pressurized liquid chamber 106, causing the ink to be ejected (sprayed) from the nozzle 104.

[0043] Then, by returning the voltage applied to the driving piezoelectric element column 121A to the reference potential, the diaphragm 102 returns to its initial position, and the pressurized liquid chamber 106 expands, generating negative pressure. At this time, ink is filled into the pressurized liquid chamber 106 from the common liquid chamber 108 through the fluid resistance section 107. After the vibration of the meniscus surface of the nozzle 104 is dampened and stabilized, the operation proceeds to the next ink ejection operation.

[0044] The head driving method described above is not limited to (pull-push-drive); pull-drive, push-drive, etc., can also be performed depending on the driving waveform applied. Note that "individual liquid chamber" 106 includes what are called liquid chambers, pressurized chambers, pressurized liquid chambers, pressure chambers, individual flow paths, pressure generating chambers, etc.

[0045] Next, the configuration of a nozzle plate according to one embodiment of the present invention will be described in more detail with reference to Figure 5.

[0046] As shown in Figure 5, the nozzle plate 200 has the following layers formed in this order from bottom to top in Figure 5: the base material 201 on which the nozzle 104 is formed, the first film 202, the second film 203, and the water-repellent film 204. The direction from bottom to top, indicated by arrow C in Figure 5, is the liquid discharge direction (the same as the direction from bottom to top in Figure 3). The first film 202, the second film 203, and the water-repellent film 204 are films formed to cover the surface of the base material 201, except for the portion on the surface of the base material 201 where the nozzle end is formed. However, other films may be provided between the base material 201, the first film 202, the second film 203, and the water-repellent film 204.

[0047] The substrate 201 can be formed from metals such as SUS, ceramics, Si, resin, etc., and in this embodiment, SUS is used. A nozzle with a diameter of approximately 10 to 30 μm is formed on this SUS substrate by pressing, etching, laser processing, etc.

[0048] The first film 202 is a hard film with high hardness, containing at least one of W, Mo, Ti, and Si, and at least one of C, N, and O. In this embodiment, the first film 202 is formed of SiC, and its film thickness is set to 100 nm. Applicable film deposition methods for the first film 202 include vapor deposition, ion plating, sputtering, MBE, and electroplating.

[0049] The second film 203 is an oxide film containing Si. The second film 203 is an adhesion film that improves the adhesion between the adjacent first film 202 and the water-repellent film 204, particularly the water-repellent film 204. The inclusion of SiO in the second film 203 allows for siloxane bonding with the water-repellent film 204, resulting in a strong bond between the second film 203 and the water-repellent film 204. In particular, in this embodiment, the second film 203 is formed of ZrSiOx containing the second transition metal Zr. Similar to the first film, deposition methods such as vapor deposition, ion plating, sputtering, MBE, and electroplating can be applied to form the second film 203.

[0050] The water-repellent film 204 can contain silicone-based or fluorine-based compounds. In this embodiment, in particular, a fluorine-based water-repellent film 204 containing a silane coupling agent is used. Applicable methods for forming the water-repellent film 204 include dipping, vapor deposition, and brush coating.

[0051] By forming a water-repellent film 204, ink droplets adhering to the surface of the nozzle plate 200 can be efficiently wiped away by a wiping action. Therefore, it is possible to suppress adverse effects on ink ejection from the nozzle and image formation caused by ink droplets adhering to the nozzle and its surroundings.

[0052] However, the wiping action applies forces such as friction to the surface of the nozzle plate 200, which can lead to a deterioration of the water-repellent properties of the nozzle plate 200 surface. For example, the water-repellent film molecules of the water-repellent film 204 may be broken, or the interfaces between the substrate 201, the first film 202, the second film 203, and the water-repellent film 204 may be damaged, resulting in a deterioration of the water-repellent properties of the nozzle plate 200 surface (hereinafter referred to as physical deterioration of water repellency). In addition, if the wiping force during the wiping action is strong, it can lead to scratches on the surface of the substrate 201 or deformation of the nozzle holes, resulting in misaligned ejection (hereinafter referred to as physical scratches). Furthermore, in recent years, with the diversification of inks used, highly alkaline inks are also used. In this case, the wiping action can break the interface between the water-repellent film 204 and the second film 203, or the siloxane bonds present in the second film 203, resulting in a deterioration of the water-repellent properties of the nozzle plate 200 surface (hereinafter referred to as chemical deterioration of water repellency).

[0053] In recent years, in particular, the use of inks containing hard particles such as metal and ceramic has become common, including inks used in 3D printing and white inks. When these hard particles are pressed against the surface of the nozzle plate 200 during the wiping operation, a stronger frictional force is generated on the surface of the nozzle plate 200, which leads to particularly noticeable deterioration of physical water repellency and physical scratches.

[0054] In contrast to these, in this embodiment, the first film 202 is formed as a hard film by including at least one of W, Mo, Ti, and Si, and at least one of C, N, and O. This increases the overall hardness of the film formed on the surface of the substrate 201, and reduces the penetration of ink particles, such as hard particles, into the water-repellent film 204. This reduces the frictional and shear forces generated between the ink particles and the water-repellent film 204 during wiping, thereby suppressing physical deterioration of water repellency and physical scratches.

[0055] Furthermore, because the second film 203 is a Si-containing oxide film, it can form siloxane bonds with the water-repellent film 204, as described above. This improves alkali resistance and suppresses chemical degradation of water repellency. Also, the siloxane bonds strengthen the bonds between the films compared to the case where the second film 203 is not formed, i.e., when the water-repellent film 204 is formed directly on the first film 202, thereby suppressing physical degradation of water repellency. In addition, the second film 203 strengthens the bond between each film and the metal substrate 201, such as stainless steel.

[0056] As described above, in this embodiment, by providing the first film 202 and the second film 203 in this order between the substrate 201 and the water-repellent film 204, physical deterioration of water repellency, physical scratches, and chemical deterioration of water repellency can be suppressed. In other words, the durability of the nozzle plate 200 surface can be improved, and its water repellency can be maintained over a long period of time. Therefore, even if an ink using hard particles is used, its water repellency will not be impaired over a long period of time. This prevents adverse effects on ink ejection and image formation due to the adhesion of ink droplets on and around the nozzle over a long period of time.

[0057] Furthermore, in this embodiment, the hardness decreases towards the surface, starting from the hardest substrate 201 side, with the first film 202, the second film 203, and the water-repellent film 204. Therefore, compared to cases where only the first film 202 and the water-repellent film 204, or only the second film 203 and the water-repellent film 204, are formed on the substrate 201, the difference in hardness between adjacent films can be reduced. Consequently, the films can be made more compatible with each other, and the bonding between the films can be enhanced.

[0058] Furthermore, the second film 203 preferably contains a second transition metal or a third transition metal M, such as the second transition metal Zn in this embodiment. Due to its ionic radius and bonding strength with oxygen, metal M can substitute for Si in the Si-O network within the second film 203 without disrupting the network. This allows for strong bonding with the water-repellent film 204 and alkali resistance. Therefore, physical and chemical degradation of water repellency can be suppressed. In addition, the bonding with the water-repellent film 204 and alkali resistance in the second film 203 depend on the ratio of the elemental amounts of Si and M, and are in a trade-off relationship. That is, since the second or third transition metal M is less likely to bond to the second film 203 compared to Si, if there is too much M, the water-repellent film 204 becomes rough and cannot repel ink sufficiently, reducing its water repellency. On the other hand, if there is too little M, substitution with Si is not sufficient, and Si-O becomes easily cleaved. In other words, the nozzle plate 200 surface does not obtain sufficient alkali resistance, and water repellency deteriorates prematurely. For these reasons, the ratio of the second or third transition metal M in the second film 203 is set to 1-20 at%. This allows for both good alkali resistance and water repellency of the nozzle plate surface. To obtain more ideal alkali resistance, it is preferable to set the ratio of M in the range of 10-20 at%.

[0059] Furthermore, it is preferable that the surface roughness Ra of the surface of the substrate 201 facing the first film 202 is 10 nm or less. If the surface of the substrate 201 forming each film has large irregularities, stress tends to concentrate locally during the wiping operation, making it easier for the water-repellent film to be physically damaged or peeled off. Therefore, it is preferable to set the surface roughness Ra of the surface of the substrate 201 facing the first film 202 to 10 nm or less, as this reduces the stress generated during the wiping operation and improves the durability of the nozzle plate 200 surface.

[0060] The first film 202 may also contain Cr instead of W, Mo, Ti, and Si. However, the first film 202 containing Cr has lower hardness compared to the first film 202 containing at least one of W, Mo, Ti, and Si. As a result, the hardness of the nozzle plate 200 surface becomes insufficient, especially against physical deterioration of water repellency and physical scratches. In particular, when hard particles are used in the ink, the wiping force during the wiping operation becomes stronger as described above, and the hardness of the first film 203 containing Cr is insufficient. However, by including a second or third transition metal M in the second film 203, a strong bonding relationship with the water-repellent film 204 can be achieved as described above, improving durability against physical deterioration of water repellency and physical scratches. In addition, by setting the surface roughness Ra of the surface of the substrate 201 on the side of the first film 202 to 10 nm or less, the durability of the nozzle plate 200 surface can be improved as described above, compensating for the low hardness of the first film 202. Therefore, the combination of a first film 202 containing Cr and at least one of C, N, or O, and a second film 203 which is an oxide film containing Si and a second or third transition metal M, provides sufficient durability for the nozzle plate 200 surface, and even if hard particles are used in the ink, physical deterioration of water repellency and physical scratching can be suppressed.

[0061] Furthermore, if the first film 202 contains Cr, it is necessary to control the manufacturing environment and other manufacturing conditions to prevent the generation of hexavalent chromium, which is subject to RoHS regulations. This may lead to stricter manufacturing conditions for the first film 202 and increased costs. Hexavalent chromium is generated when chromium compounds react with oxygen in high temperatures or acidic environments during the manufacturing process of the first film 202, resulting in oxidation. For example, when forming the first film 202, if Cr is deposited by sputtering or vapor deposition, the target material or precursor may be exposed to impurities (such as oxygen and moisture) and oxidized, or oxidized after the formation of the first film 202, potentially generating hexavalent chromium. In particular, when a second film 203 having an oxide film such as SiO2 or ZrSiO is formed on top of a first film 202 containing Cr, Cr may oxidize and generate hexavalent chromium. As in this embodiment, by forming the first film 202 without Cr and containing at least one of W, Mo, Ti, or Si, it is possible to prevent the generation of such hexavalent chromium and improve the manufacturing conditions for forming each film on the substrate 201 containing the first film 202.

[0062] In this embodiment, SUS is used as the material for the base material 201. SUS is preferable because it is superior to other materials in terms of processability, cost, and ink resistance. Furthermore, forming the base material 201 with a metal material such as SUS improves the wettability with various types of droplets, which is also preferable. Wettability, as used here, refers to the property that the base material 201 does not dissolve or swell upon contact with droplets. On the other hand, using SUS as the material for the base material 201 tends to increase its surface roughness Ra, for example, to several hundred nanometers, which can easily lead to stress concentration during the wiping operation. Therefore, applying the above film configuration of this embodiment to a SUS base material 201 is preferable because it improves the durability of the nozzle plate 200 surface and suppresses physical deterioration of water repellency and physical scratches.

[0063] Furthermore, as in this embodiment, it is preferable that the first film 202 contains SiC. SiC has higher hardness compared to other combinations that can be used for the first film 202. In addition, oxidation of the first film 202 containing SiC forms a thin layer of SiO2 on its surface, which improves bonding with the SiO contained in the second film 203. Therefore, the bonding between the first film 202 and the second film 203 can be improved, further enhancing the durability of the nozzle plate 200 surface.

[0064] Using a water-repellent film 204 that contains fluorine is preferable because it increases the contact angle with the ink, thereby improving water repellency.

[0065] Furthermore, it is preferable that the water-repellent film 204 contains a silane coupling agent. This facilitates the formation of siloxane bonds between the second film 203 and the water-repellent film 204, thereby increasing the bonding strength between the second film 203 and the water-repellent film 204.

[0066] Furthermore, it is preferable that the first film 202 has a thickness of 30 nm or more and 300 nm or less. Considering the variation in the formation of the first film 202, it is preferable to have a thickness of 30 nm or more in order to ensure its quality. Also, by making the thickness of the first film 202 300 nm or less, the contact angle with the ink can be made to a predetermined level or higher, which is preferable.

[0067] Figure 6 shows the relationship between the film thickness of the first film 202 and the contact angle with the ink. The nozzle plate configuration is the same as that of this embodiment described above. In Figure 6, the contact angles are measured before and after the wiping operation for each sample in which only the film thickness was changed.

[0068] As shown in Figure 6, the contact angle is largest when the thickness of the first film 202 is 100 nm, and the contact angle decreases as the thickness increases. In the range of 300 nm or less, a contact angle sufficient to exhibit good water repellency can be obtained. Therefore, it is preferable to set the thickness of the first film 202 to 300 nm or less.

[0069] Furthermore, setting the thickness of the first film 202 to 100 nm or less is preferable because it ensures adhesion between each film and the substrate 201, thereby suppressing lift-off of the second film 203 and the water-repellent film 204. When the first film 202 was deposited on the Si wafer substrate 201, film lifting and delamination were particularly effectively prevented at a thickness of 100 nm or less. For this reason, it is more preferable that the thickness of the first film 202 be between 30 nm and 100 nm. In addition, when the thickness of the first film 202 is in the range of 30 nm to 50 nm, color changes due to film deposition variations are reduced, and a deep blue film can be stably formed, resulting in excellent appearance quality, which is particularly preferable.

[0070] Figure 7 shows the effects of providing the first film 202 and the second film 203 in this embodiment, and is a diagram showing the results of measuring the contact angle before and after the wiping operation in the example and comparative example. In Figure 7, the cases in which only the first film 202 is provided between the substrate 201 and the water-repellent film 204 are: Comparative Example 1, the case in which only the second film 203 is provided (Comparative Example 2), and the case in which both the first film 202 and the second film 203 are provided (Example).

[0071] The substrate 201 and the composition of each film are based on the above embodiment. Specifically, the substrate 201 is made of SUS, the first film 202 has a thickness of 100 nm and contains SiC, the second film 203 is a Si oxide film containing 10 at% Zr, and the water-repellent film 204 is a fluorine-based water-repellent film containing a silane coupling agent. The first film is formed by ion plating, the second film by sputtering, and the water-repellent film by vacuum deposition.

[0072] As shown in Figure 7, after the wiping operation, the contact angle of the embodiment is larger than that of Comparative Examples 1 and 2. In Comparative Example 1, which only had the first film 202, it is thought that a siloxane bond could not be formed with the water-repellent film 204, resulting in insufficient physical durability and alkali resistance of the nozzle plate 200 surface. Therefore, physical deterioration of water repellency, physical scratches, and chemical deterioration of water repellency could not be sufficiently suppressed, resulting in a smaller contact angle. Similarly, in Comparative Example 2, which only had the second film 203, the overall hardness of the film was insufficient, so physical deterioration of water repellency and physical scratches could not be sufficiently suppressed, resulting in a smaller contact angle. Thus, it can be seen that by incorporating the first film 202 and the second film 203 of this embodiment, the nozzle plate 103 surface has sufficient durability against physical deterioration of water repellency, physical scratches, and chemical deterioration of water repellency, and can maintain a large contact angle even after the wiping operation.

[0073] Furthermore, it is preferable that the hardness of the first film 202 be 16 GPa or higher. This allows the hardness of each film formed on the surface of the nozzle plate 200 to be sufficiently increased as described above, and sufficient durability of the nozzle plate 200 surface can be ensured. The hardness of the first film 202 refers to the hardness in the state in which the first film 202 is formed on the substrate 201.

[0074] The measurement conditions for measuring the hardness of the first film 202 in this embodiment are shown below. The test was performed with the first film 202 deposited on the substrate 201 shown below, and the first film 202 is the same as the one used in the experiment in Figure 7. <Test Conditions> Test method: Nanoindenter test Equipment: Nanoindenter G200 manufactured by Toyo Technica Measurement method: Continuous stiffness measurement Head: DCM head Indenter: Berkovich Drift rate: 0.3 nm / s Indentation depth: 70-100nm Substrate: Si wafer <100> Allowable Drift Rate: 0.3nm / s Maximum indentation depth: 1000nm Excitation frequency: 75Hz Displacement amplitude: 1 nm Percent to Unload: 90% Strain rate: 0.05 l / s Poisson ratio: 0.3

[0075] Under the above conditions, tests were conducted on N=19 samples, resulting in an average hardness of 18.3 GPA and 3σ = 2.2 GPa. As shown in the example in Figure 7 above, it was found that the first film 202 of this embodiment provides sufficient hardness to the entire film, and maintains a sufficient contact angle even after the wiping operation. From the above, it can be seen that the hardness of the first film 202 of this embodiment, that is, a hardness of 16 GPa or higher, ensures sufficient durability of the nozzle plate 200 surface against physical deterioration of water repellency and physical scratches during the wiping operation.

[0076] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

[0077] In this application, the discharged liquid is not particularly limited as long as it has a viscosity and surface tension that can be discharged from the head, but it is preferable that its viscosity becomes 30 mPa·s or less at room temperature and atmospheric pressure, or when heated or cooled. More specifically, it is a solution, suspension, emulsion, etc. containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a polymerizable compound, a resin, a functional material such as a surfactant, a biocompatible material such as DNA, amino acids or proteins, calcium, or an edible material such as a natural pigment. These can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic elements and light-emitting elements or electronic circuit resist patterns, and three-dimensional molding material liquids.

[0078] The term "liquid" includes not only ink but also paints, pre-treatment solutions, binders, and overcoat solutions.

[0079] The pressure generating means of the present invention includes those that use piezoelectric actuators (multilayer piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a diaphragm and a counter electrode.

[0080] A "liquid discharge unit" is a liquid discharge head with integrated functional components and mechanisms, and includes an assembly of parts related to liquid discharge. For example, a "liquid discharge unit" may include a combination of a liquid discharge head with at least one of the following components: a head tank, carriage, supply mechanism, maintenance and recovery mechanism, main scanning movement mechanism, and liquid circulation device.

[0081] Here, integration includes, for example, cases where the liquid dispensing head and functional components or mechanisms are fixed to each other by fastening, bonding, engaging, etc., or where one is held movably relative to the other. Furthermore, the liquid dispensing head and functional components or mechanisms may be configured to be detachable from each other.

[0082] For example, some liquid dispensing units have a liquid dispensing head and head tank integrated into one unit. Others have a liquid dispensing head and head tank integrated into one unit, connected to each other by tubes or similar means. In these liquid dispensing units, a unit including a filter can also be added between the head tank and the liquid dispensing head.

[0083] Additionally, some liquid dispensing units have an integrated liquid dispensing head and carriage.

[0084] Furthermore, some liquid dispensing units integrate the liquid dispensing head and the scanning mechanism by movably holding the liquid dispensing head in a guide member that constitutes part of the scanning mechanism. Others integrate the liquid dispensing head, carriage, and main scanning mechanism.

[0085] Furthermore, some liquid dispensing units integrate the liquid dispensing head, carriage, and maintenance / recovery mechanism by fixing a cap component, which is part of the maintenance / recovery mechanism, to a carriage to which the liquid dispensing head is attached.

[0086] Furthermore, some liquid discharge units have a head tank or a liquid discharge head to which flow path components are attached, to which a tube is connected, integrating the liquid discharge head and the supply mechanism. Through this tube, the liquid from the liquid storage source is supplied to the liquid discharge head.

[0087] The main scanning movement mechanism shall include the guide member alone. The supply mechanism shall also include the tube alone and the loading section alone.

[0088] Here, the "liquid dispensing unit" is described in combination with a liquid dispensing head, but the "liquid dispensing unit" also includes a head module or head unit that includes the liquid dispensing head mentioned above, as well as the functional components and mechanisms described above, all integrated together.

[0089] A "liquid dispensing device" includes devices that drive a liquid dispensing head to dispense liquid, such as a liquid dispensing head, liquid dispensing unit, head module, and head unit. Liquid dispensing devices include not only devices that can dispense liquid onto surfaces to which liquid can adhere, but also devices that dispense liquid into air or into liquid.

[0090] This "liquid dispensing device" may also include means for feeding, transporting, and dispensing paper onto materials to which liquid can adhere, as well as pre-treatment devices, post-treatment devices, etc.

[0091] For example, "liquid ejection devices" include image forming devices that eject ink to form images on paper, and three-dimensional molding devices that eject molding liquid into a powder layer formed in layers to create three-dimensional objects.

[0092] Furthermore, the term "liquid dispensing device" is not limited to those that visualize meaningful images such as letters or figures through the dispensed liquid. For example, it also includes devices that form patterns that do not have meaning in themselves, or devices that create three-dimensional images.

[0093] The term "material to which liquid can adhere" above refers to a material to which liquid can adhere at least temporarily, such as material to which liquid adheres and solidifies, or material to which liquid adheres and penetrates, and is the recording medium in the above embodiment. Specific examples include recording media such as paper, recording paper, film, and cloth; electronic components such as electronic circuit boards and piezoelectric elements; powder layers; organ models; and inspection cells. Unless otherwise specified, it includes all materials to which liquid can adhere.

[0094] The materials referred to as "materials to which liquid can adhere" above include paper, thread, fibers, fabrics, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere to them, even temporarily.

[0095] Other examples of "liquid dispensing devices" include processing liquid coating devices that dispense processing liquid onto the surface of paper for purposes such as modifying the paper surface, and injection granulation devices that granulate fine particles of raw materials by spraying a compositional liquid, in which raw materials are dispersed in a solution, through a nozzle.

[0096] In this application, the terms image formation, recording, printing, copying, printing, and shaping are all considered synonymous.

[0097] Examples of the present invention are as follows: <1> A nozzle plate equipped with a nozzle for discharging liquid, From the upstream side to the downstream side in the liquid discharge direction from the nozzle, the substrate on which the nozzle is formed, the first film, the second film, and the water-repellent film are formed in this order. The first film comprises at least one of W, Mo, Ti, and Si, and at least one of C, N, and O. The nozzle plate is characterized in that the second film is an oxide film containing Si. <2> The surface roughness Ra of the first film-side surface of the substrate is 10 nm or less. <1> This is the nozzle plate described. <3> The first film contains SiC. <1> or <2> This is the nozzle plate described. <4> The second film contains a second or third transition metal, and the ratio of the second or third transition metal in the second film is 1 to 20 at%. <1> from <3> It is one of the nozzle plates listed. <5> The ratio of the second or third transition metal in the second film is 10-20 at%. <4> This is the nozzle plate described. <6> The water-repellent film contains a silane coupling agent. <1> from <5> It is one of the nozzle plates listed. <7> The water-repellent film contains fluorine. <1> from <6> It is one of the nozzle plates listed. <8> The thickness of the first film is between 30 nm and 300 nm. <1> from <7> It is one of the nozzle plates listed. <9> The thickness of the first film is between 30 nm and 100 nm. <1> from <7> It is one of the nozzle plates listed. <10> The thickness of the first film is between 30 nm and 50 nm. <1> from <7> It is one of the nozzle plates listed. <11> The hardness of the first film on the substrate is 16 GPa or higher. <1> from <10> It is one of the nozzle plates listed. <12> A nozzle plate equipped with a nozzle for discharging liquid, From the upstream side to the downstream side in the liquid discharge direction from the nozzle, the substrate on which the nozzle is formed, the first film, the second film, and the water-repellent film are formed in this order. The first film comprises Cr and at least one of C, N, and O. The second film is an oxide film containing Si and a second or third transition metal. The nozzle plate is characterized in that the surface roughness Ra of the first film-side surface of the substrate is 10 nm or less. <13> The second film contains a second or third transition metal, and the ratio of the second or third transition metal in the second film is 1 to 20 at%. <12> This is the nozzle plate described. <14> The ratio of the second or third transition metal in the second film is 10-20 at%. <13> This is the nozzle plate described. <15> The water-repellent film contains a silane coupling agent. <12> from <14> It is one of the nozzle plates listed. <16> The water-repellent film contains fluorine. <12> from <15> It is one of the nozzle plates listed. <17> The thickness of the first film is between 30 nm and 300 nm. <12> from <16> It is one of the nozzle plates listed. <18> The thickness of the first film is between 30 nm and 100 nm. <12> from <16> It is one of the nozzle plates listed. <19> The thickness of the first film is between 30 nm and 50 nm. <12> from <16> It is one of the nozzle plates listed. <20> The hardness of the first film on the substrate is 16 GPa or higher. <12> from <19> It is one of the nozzle plates listed. <21> <1> from <20> This is a liquid dispensing head equipped with one of the nozzle plates described above. <22> <21> This is an image forming apparatus equipped with the liquid dispensing head described above. [Explanation of Symbols]

[0098] 1. Image forming apparatus 83 Wiper blade (wiping component) 104 Nozzles 200 Nozzle Plate 201 Base material 202 First membrane 203 The second membrane 204 Water-repellent film C Liquid discharge direction [Prior art documents] [Patent Documents]

[0099] [Patent Document 1] WO2022 / 044245 publication

Claims

1. A nozzle plate equipped with a nozzle for discharging liquid, From the upstream side to the downstream side in the liquid discharge direction from the nozzle, the substrate on which the nozzle is formed, the first film, the second film, and the water-repellent film are formed in this order. The first film comprises at least one of W, Mo, Ti, and Si, and at least one of C, N, and O. The nozzle plate is characterized in that the second film is an oxide film containing Si.

2. The nozzle plate according to claim 1, wherein the surface roughness Ra of the first film-side surface of the substrate is 10 nm or less.

3. The nozzle plate according to claim 1, wherein the first film comprises SiC.

4. The nozzle plate according to claim 1, wherein the second film contains a second transition metal or a third transition metal, and the ratio of the second transition metal or third transition metal in the second film is 1 to 20 at%.

5. The nozzle plate according to claim 4, wherein the ratio of a second transition metal or a third transition metal in the second film is 10 to 20 at%.

6. The nozzle plate according to claim 1, wherein the water-repellent film comprises a silane coupling agent.

7. The nozzle plate according to claim 6, wherein the water-repellent film contains fluorine.

8. The nozzle plate according to claim 1, wherein the thickness of the first film is 30 nm or more and 300 nm or less.

9. The nozzle plate according to claim 1, wherein the thickness of the first film is 30 nm or more and 100 nm or less.

10. The nozzle plate according to claim 1, wherein the thickness of the first film is 30 nm or more and 50 nm or less.

11. The nozzle plate according to claim 1, wherein the hardness of the first film on the substrate is 16 GPa or more.

12. A nozzle plate equipped with a nozzle for discharging liquid, From the upstream side to the downstream side in the liquid discharge direction from the nozzle, the substrate on which the nozzle is formed, the first film, the second film, and the water-repellent film are formed in this order. The first film comprises Cr and at least one of C, N, and O. The second film is an oxide film containing Si and a second or third transition metal. A nozzle plate characterized in that the surface roughness Ra of the first film-side surface of the substrate is 10 nm or less.

13. A liquid dispensing head comprising a nozzle plate according to any one of claims 1 to 12.

14. An image forming apparatus comprising the liquid dispensing head according to claim 13.

Images