Inkjet head, manufacturing method therefor, and image forming apparatus

Abstract

This inkjet head comprises: a nozzle plate that has a plurality of discharge holes, a substrate having a passivation film on a surface thereof, and a base layer covering said surface; and a resin layer that is disposed on one surface of the substrate so as to be in contact with the base layer. The base layer contains silicon (Si) and carbon (C). The resin layer is a cured product of a resin composition that contains an epoxy compound represented by general formula (I) and a polythiol compound having two or more thiol groups in each molecule. (In general formula (I), R1 is H or a C1-4 alkyl group. R2 is a linking group represented by general formula (II). m is a number in the range of 0.1 to less than 50. L is an integer between 0 and 3, inclusive.) (In general formula (II), R3 and R4 are each H, or a methyl group in which some or all of H may be substituted with F.)

Description

Inkjet head, manufacturing method thereof, and image forming apparatus

[0001] The present invention relates to an inkjet head, a method for manufacturing the same, and an image forming apparatus.

[0002] An image forming apparatus having an inkjet head ejects (or sprays) minute amounts of liquid such as ink from a plurality of ejection holes (nozzles) in the inkjet head, and then causes the ejected liquid to land at predetermined positions on a recording medium to form an image.

[0003] An inkjet head has a plate-like nozzle plate with a plurality of ejection holes, and other members that form ink flow paths, pressure chambers, etc. The nozzle plate and other members are bonded together with a resin adhesive.

[0004] Patent Document 1 discloses an inkjet head that uses a resin layer as the resin adhesive, which is a cured product of a resin composition containing a specific epoxy compound and a polythiol compound having two or more thiol groups in the molecule. According to Patent Document 1, the resin layer obtained by curing the specific epoxy compound is less likely to absorb ink and therefore less likely to swell during use of the inkjet head. As a result, the resin layer is said to be able to suppress a decrease in the ink flow path rigidity due to a decrease in Young's modulus caused by swelling, which in turn reduces the pressure in the ink flow path, thereby preventing a decrease in the ink ejection reliability of the inkjet head.

[0005] Patent Document 1 further discloses a nozzle plate to be adhered to the resin layer, in which a treatment layer containing silicon (Si) and oxygen (O) is formed on the surface of a substrate such as stainless steel (SUS). According to Patent Document 1, the Si contained in this treatment layer enhances adhesion to the resin layer. Also, according to Patent Document 1, the strong Si-O bonds contained in the treatment layer make the inkjet head less susceptible to corrosion even when in contact with liquids such as ink, thereby enhancing the durability of the inkjet head. The inkjet head described in Patent Document 1 has improved adhesion and durability due to the treatment layer containing Si and O.

[0006] Japanese Patent Application Laid-Open No. 2015-221541

[0007] According to Patent Document 1, the resin layer can suppress a decrease in the ejection reliability of the inkjet head. However, according to the investigations of the present inventors, the inkjet head described in Patent Document 1 suffers from a significant decrease in adhesive strength between the nozzle plate and other members, particularly when alkaline ink or ink containing a high concentration of methylpyrrolidone is used.

[0008] The present invention has been made in view of the above problems. An object of the present invention is to provide an inkjet head having a resin layer obtained by curing a specific epoxy compound, and in which the adhesive strength between the nozzle plate and other members is not easily reduced even when alkaline ink or ink containing a high concentration of methylpyrrolidone is used. Another object of the present invention is to provide a method for manufacturing the inkjet head. A still further object of the present invention is to provide an image forming apparatus having the inkjet head.

[0009] One aspect of the present invention for solving the above problems relates to inkjet heads according to the following items [1] to [8]: [1] An inkjet head comprising: a nozzle plate having a substrate with a passivation film on its surface and an underlayer covering the surface, the nozzle plate having a plurality of ejection holes; and a resin layer disposed on one surface of the substrate in contact with the underlayer, the underlayer containing silicon (Si) and carbon (C), the resin layer being a cured product of a resin composition containing an epoxy compound represented by general formula (I) and a polythiol compound having two or more thiol groups in its molecule.

[0010]

[0011] (In general formula (I), R １ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ２ are independently a linking group represented by general formula (II), m is a number of 0.1 or more and less than 50, and L is independently an integer of 0 or more and 3 or less.

[0012]

[0013] (In general formula (II), R３ and R ４ are independently a hydrogen atom or a methyl group in which some or all of the hydrogen atoms may be substituted with fluorine atoms.) [2] The inkjet head according to [1], wherein the resin layer is a cured product of a resin composition further containing an imidazole compound represented by general formula (III):

[0014]

[0015] (In general formula (III), R ５ , R ６ and R ７ each independently represents an atom or a substituent selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group; R ８ each independently represents an alkylene group or an arylene group having 1 to 20 carbon atoms; R ９When k is 1, it is a hydrogen atom, or an atom or substituent selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an aryl group, and a cyanomethyl group; when K is an integer of 2 to 6, it is a hydrocarbon group having 1 to 20 carbon atoms, j is 0 or 1, and k is an integer of 1 to 6.) [3] The inkjet head according to [1] or [2], wherein the substrate contains at least one element selected from the group consisting of chromium (Cr), iron (Fe), nickel (Ni), molybdenum (Mo), and palladium (Pd). [4] The inkjet head according to any of [1] to [3], wherein the underlayer has a maximum peak P of binding energy of the Si 2p orbital in the surface portion measured by X-ray photoelectron spectroscopy of 99.6 (eV) to 101.9 (eV). [5] The inkjet head according to any one of [1] to [4], wherein the oxygen (O) atom number distribution in the depth direction of the underlayer, as measured by X-ray photoelectron spectroscopy, is higher on the surface side opposite the substrate and lower on the substrate side. [6] The inkjet head according to any one of [1] to [5], wherein the oxygen (O) atom number distribution in the underlayer, as measured by X-ray photoelectron spectroscopy, is higher on one surface side on which the resin layer is disposed and lower toward the other surface opposite the resin layer. [7] The inkjet head according to any one of [1] to [6], wherein the nozzle plate has a liquid-repellent layer on the other surface opposite the resin layer. [8] The inkjet head according to [7], wherein the underlayer continuously covers the surface of the substrate that constitutes the ejection holes, from the liquid-repellent layer to the resin layer.

[0016] Another aspect of the present invention for solving the above problems relates to a method for manufacturing an inkjet head according to the following items [9] to

[12] : [9] A method for manufacturing an inkjet head, comprising the steps of: preparing a substrate having a plurality of ejection holes and having a passivation film formed on the surface thereof; forming an underlayer containing silicon (Si) and carbon (C) on the surface of the substrate; arranging a resin composition on one surface of the substrate in contact with the underlayer, the resin composition containing an epoxy compound represented by general formula (I) and a polythiol compound having two or more thiol groups in its molecule; and curing the resin composition. (In general formula (I), R １ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ２ are independently a linking group represented by general formula (II), m is a number of 0.1 or more and less than 50, and L is independently an integer of 0 or more and 3 or less. (In general formula (II), R ３ and R ４ are independently hydrogen atoms or methyl groups in which some or all of the hydrogen atoms may be substituted with fluorine atoms.)

[10] The method for manufacturing an inkjet head according to [9], comprising the steps of forming a liquid-repellent layer on a surface of the substrate on which the underlayer has been formed, and removing the liquid-repellent layer from one of the surfaces before disposing the resin composition.

[11] The method for manufacturing an inkjet head according to

[10] , in which the liquid-repellent layer is removed by a plasma removal method.

[12] The method for manufacturing an inkjet head according to any of [9] to

[11] , in which the underlayer is formed by a chemical vapor deposition method.

[0017] Another aspect of the present invention for solving the above problem relates to an image forming apparatus according to the following item

[13] :

[13] An image forming apparatus having the inkjet head according to any one of items [1] to [8].

[0018] According to the present invention, it is possible to provide an inkjet head that has a resin layer obtained by curing a specific epoxy compound, and that is less likely to experience a decrease in adhesive strength between the nozzle plate and other members even when alkaline ink or ink containing a high concentration of methylpyrrolidone is used.

[0019] FIG. 1 is a diagram showing a schematic configuration of an inkjet printer including an inkjet head according to an embodiment. FIG. 2 is a block diagram showing the main components of a control system of the inkjet printer. FIG. 3 is a diagram showing a schematic arrangement of inkjet heads in a head unit of the inkjet printer. FIG. 4 is a perspective view showing the appearance of an inkjet head. FIG. 5A is a diagram showing a schematic cross-sectional view of a main portion of an inkjet head taken along the short side of a head chip. FIG. 5B is a diagram showing a schematic cross-sectional view of a main portion of an inkjet head taken along the long side of a head chip. FIG. 6 is a diagram showing a planar configuration of the periphery of a nozzle in an inkjet head. FIG. 7 is a diagram showing a schematic cross-sectional view of a first substrate (nozzle plate) and a second substrate (piezoelectric element) in an inkjet head according to an embodiment, in the vicinity of a nozzle (region 59a shown in FIG. 5B). FIG. 8 is a diagram showing a schematic cross-sectional view of a first substrate (nozzle plate) and a second substrate (piezoelectric element) in the vicinity of a nozzle (region 59a shown in FIG. 5B) in an inkjet head according to a modification of the present embodiment. 9A to 9D are diagrams schematically showing a method for manufacturing an inkjet head according to an embodiment, and FIGS. 10A to 10C are diagrams schematically showing a method for manufacturing an inkjet head according to an embodiment.

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] [Inkjet Printer 1] Fig. 1 is a diagram showing the schematic configuration of an inkjet printer equipped with an inkjet head according to this embodiment, and Fig. 2 is a block diagram showing the main parts of the control system of the inkjet printer. The inkjet printer described below is an example of an image forming apparatus.

[0022] As shown in Figures 1 and 2, the inkjet printer 1 includes a transport unit 10, a supply unit 20, a discharge unit 30, an ink supply unit 40, a drawing unit 50, a reading unit 60, an operation display unit 70, an input / output interface 80, and a control unit 90.

[0023] The transport unit 10 has multiple components related to transport, such as a transport belt 11, a drive roller 12, and a driven roller 13. The transport unit 10 transports the recording medium M by the transport operation of the multiple components, such as the transport belt 11. Specifically, in the transport unit 10, the transport belt 11 is stretched across the drive roller 12 and the driven roller 13, and is driven by driving the drive roller 12 to rotate. As a result, the recording medium M supplied from the supply unit 20 is transported to the imaging unit 50 while placed on the transport surface 11a of the transport belt 11, and after imaging (also referred to as image formation or printing) in the imaging unit 50, is transported to the discharge unit 30.

[0024] The recording medium M can be any of a variety of media capable of fixing the ink ejected from the inkjet head 55. The recording medium M is, for example, a sheet-like medium made of a material such as sheet paper, cloth (fabric), or resin. The recording medium M is not limited to a sheet-like medium, and may also be a roll-like medium such as paper, cloth, or resin. An example of a resin recording medium M is a PCB (Printed Circuit Board) substrate. In the case of a PCB (Printed Circuit Board) substrate, drawing using the inkjet printer 1 can be applied to printing solder resist or marking ink on the PCB substrate. Other examples of the recording medium M that can be used for drawing include the metal body of an automobile, building materials (exterior walls, roofing materials, tiles, etc.), and cans (metal cans for holding food, beverages, etc.).

[0025] 1 illustrates, as an example of an image forming apparatus, a conveying unit 10 that conveys a recording medium M with a conveying belt 11. However, the conveying unit 10 is not limited to the conveying belt 11, and may be configured to convey the recording medium M with a drum or roller.

[0026] The supply unit 20 has a supply stacking unit 21 that stacks and stores a plurality of recording media M, a supply conveying unit 22 that conveys and supplies the recording media M from the supply stacking unit 21 to the conveying unit 10, etc. The supply stacking unit 21 is configured to be able to rise and fall, and when the topmost recording medium M is conveyed to the conveying unit 10 by the supply conveying unit 22, the supply stacking unit 21 rises so that the recording medium M that has become the topmost after the conveying can be conveyed to the supply conveying unit 22.

[0027] The discharge unit 30 has a discharge stacking section 31 that stores a stack of multiple recording media M, and a discharge conveying section 32 that conveys the recording media M discharged from the conveying section 10 to the discharge stacking section 31. The discharge stacking section 31 is configured to be able to rise and fall, and when the recording media M is conveyed from the discharge conveying section 32 to the discharge stacking section 31, the discharge stacking section 31 descends.

[0028] The supply conveying unit 22 and the discharge conveying unit 32 have, for example, a plurality of rollers, and convey the recording medium M by rotating the rollers. The supply conveying unit 22 and the discharge conveying unit 32 are not limited to rollers, and may be configured with a belt, or may be configured with a combination of rollers and belts.

[0029] When a roll-shaped medium is used as the recording medium M, an unwinding roller on which the roll-shaped medium is stored in a wound state and a winding roller that winds up the roll-shaped medium are used instead of the supply stacking unit 21 and the discharge stacking unit 31. The roll-shaped medium is transported to the transport unit 10 by rotating the unwinding roller, and is wound up onto the winding roller by rotating the winding roller.

[0030] A post-processing device may be provided between the conveying unit 10 and the discharging unit 30 to perform post-processing on the recording medium M on which an image has been formed by the imaging unit 50. Examples of post-processing devices include a fixing device that fixes ink to the recording medium M. For example, when ultraviolet-curable ink is used as the ink, a fixing device is used that irradiates ultraviolet light onto the recording medium M to fix the ink to the recording medium M. When aqueous ink or solvent ink is used as the ink, a fixing device is used that fixes the ink to the recording medium M by a method such as drying. Furthermore, devices other than a fixing device, such as a cutting device that cuts the recording medium M to a desired length, may also be used as the post-processing device.

[0031] The configurations of the transport unit 10, the supply unit 20, and the discharge unit 30 can be modified in various ways depending on the type of recording medium M to be imaged.

[0032] The ink supply unit 40 is a device that supplies ink to a first sub-tank 52a of the drawing unit 50, which will be described later. The ink supply unit 40 has a main tank 41 and components related to ink supply (e.g., a pump, a valve, etc.) not shown. The main tank 41 stores ink to be supplied to the first sub-tank 52a at room temperature. The ink supply unit 40 supplies ink from the main tank 41 to the first sub-tank 52a via a flow path 42 using a pump or the like (not shown).

[0033] The heating unit 95 is disposed upstream of the imaging unit 50 in the transport direction T of the recording medium M, and heats the recording medium M transported by the transport belt 11 to a predetermined temperature. The heating unit 95 is connected to the control unit 90 (see FIG. 2 ) and is controlled by the control unit 90.

[0034] For example, the heating unit 95 has an infrared heater or the like, and when power is supplied to the infrared heater based on a control signal supplied from the control unit 90, the infrared heater generates heat and heats the recording medium M to a predetermined temperature. Depending on the type of ink used, the heating unit 95 may not be necessary. In FIG. 1 , the inkjet printer 1 has the heating unit 95 arranged on the upper surface side of the conveyor belt 11. However, the inkjet printer 1 may have a heating unit arranged on the lower surface side of the conveyor belt 11 instead of (or in addition to) the heating unit 95, and heat the conveyor belt 11 and thereby heat the recording medium M.

[0035] The image forming unit 50 includes a carriage 51, a first sub-tank 52a, a second sub-tank 52b, flow paths 53a, 53b, and 53c, a head driving unit 54, an inkjet head 55, and the like (see FIGS. 1 and 2).

[0036] 1 shows ink supply units 40 and drawing units 50 for one color for simplicity, but the ink supply units 40 and drawing units 50 are arranged according to the number of colors used. For example, when four colors, yellow (Y), magenta (M), cyan (C), and black (K), are used, ink supply units 40 and drawing units 50 for four colors are arranged, and the drawing units 50 are arranged so as to be aligned at predetermined intervals along the transport direction T.

[0037] Although a plurality of second sub-tanks 52b and heads 55 are connected downstream of the first sub-tank 52a, only one of each is shown in FIG. 1 for the sake of simplicity.

[0038] The carriage 51 is a housing that holds inside it the first sub-tank 52a, the second sub-tank 52b, the flow paths 53a, 53b, and 53c, the head drive unit 54, the head 55, and other devices and components required for image formation. Although not shown, the carriage 51 may also have an ink heating unit that heats and maintains the ink inside the carriage 51.

[0039] The first sub-tank 52a is connected to the downstream side of the main tank 41. The first sub-tank 52a stores ink supplied from the main tank 41 inside the carriage 51. The ink in the sub-tank 52 is supplied to the second sub-tank 52b via a flow path 53a using a pump or the like (not shown) inside the carriage 51.

[0040] A plurality of second sub-tanks 52b are connected downstream of the first sub-tank 52a. The second sub-tanks 52b store ink supplied from the first sub-tank 52a within the carriage 51. The ink in the second sub-tank 52b is supplied to a manifold 56 of the head 55 (described later) via a flow path 53b using a pump or the like (not shown) within the carriage 51. A portion of the ink supplied to the manifold 56 is returned (recovered) to the second sub-tank 52b via a flow path 53c, allowing it to be resupplied to the manifold 56. In other words, the ink circulates between the second sub-tank 52b and the manifold 56 via the flow paths 53b and 53c. This circulation path also includes a plurality of individual circulation paths 111a, a common circulation path 112a, and a vertical circulation path 112b (described later) (see FIGS. 5A, 5B, and 6).

[0041] Based on the control of a control unit 90 (described later), the head driving unit 54 outputs a driving voltage corresponding to the image data of the image to be formed to a piezoelectric element 58 of a head 55 (described later). The driving voltage from the head driving unit 54 drives the piezoelectric element 58, causing ink to be ejected from a nozzle 59 of the head 55 (described later) in an amount corresponding to the image data.

[0042] A plurality of heads 55 are connected to the downstream sides of the plurality of second sub-tanks 52b, respectively. That is, a plurality of second sub-tanks 52b and heads 55 are connected to the downstream sides of the first sub-tanks 52a.

[0043] The head 55 has a manifold 56 (an example of a common supply flow path), individual supply flow paths 57, piezoelectric elements 58, nozzles 59, individual circulation flow paths 111a, a common circulation flow path 112a, and a vertical circulation flow path 112b (see FIGS. 5A, 5B, and 6), etc. The head 55 has a plurality of nozzles 59, and the individual supply flow paths 57 and piezoelectric elements 58 are provided in accordance with the number of nozzles 59.

[0044] The manifold 56 communicates with a plurality of individual supply channels 57, and ink supplied to the manifold 56 is supplied to the individual supply channels 57. A part or the entirety of each individual supply channel 57 is a chamber having an internal space capable of temporarily storing ink ejected from the nozzles 59. A piezoelectric element 58 is provided on the wall surface of each individual supply channel 57. One end of each nozzle 59 communicates with the individual supply channel 57, and the other end is an open end.

[0045] A driving voltage is applied to the piezoelectric element 58 from the head driving unit 54. When the driving voltage from the head driving unit 54 is applied to the piezoelectric element 58, the piezoelectric element 58 deforms in accordance with the applied driving voltage, which deforms the individual supply flow path 57. The deformation of the individual supply flow path 57 causes a pressure change in the ink in the individual supply flow path 57 that is supplied to the nozzle 59.

[0046] Therefore, when a drive voltage from the head drive unit 54 is applied to the piezoelectric element 58, the piezoelectric element 58 and the individual supply flow path 57 are deformed, causing a pressure change in the ink in the individual supply flow path 57, and as a result, the ink in the individual supply flow path 57 is ejected from the nozzle 59. In this way, an image can be formed on the recording medium M by ejecting ink from the nozzle 59.

[0047] In the carriage 51, the heads 55 may be configured to employ a single-pass (one-pass) system in which an image is formed in one scan, or a scan (multi-pass) system in which an image is formed in multiple scans. In the single-pass system, the carriage 51 is provided with heads 55 in the width direction of the recording medium M (a direction perpendicular to the conveying direction T of the recording medium M), the number of which corresponds to the image formation width (see FIG. 3). As shown in FIG. 3, the multiple heads 55 are arranged in one or multiple rows with their longitudinal directions aligned with the width direction of the recording medium M, and in each head 55, the multiple nozzles 59 are arranged linearly or in a grid pattern along the longitudinal direction of the head 55.

[0048] The reading unit 60 is disposed downstream of the drawing unit 50 in the transport direction T of the recording medium M, and reads an image (for example, a predetermined pattern image) formed on the recording medium M transported by the transport belt 11. The reading unit 60 outputs the reading result of the predetermined pattern image to the control unit 90. The control unit 90 changes the image formation conditions, for example, the image formation position and the driving conditions of the head 55, based on the reading result.

[0049] Although not shown, the inkjet printer 1 also includes a maintenance unit that performs maintenance such as cleaning of the head 55 .

[0050] The operation display unit 70 is, for example, a flat panel display such as a liquid crystal display with a touch panel or an organic electroluminescence (EL) display. The operation display unit 70 displays operation menus for the user, information related to image data, various states of the inkjet printer 1, etc. The operation display unit 70 also has a plurality of keys and accepts various input operations from the user.

[0051] The input / output interface 80 mediates the transmission and reception of data between the external device 99 and the control unit 90. The input / output interface 80 is configured, for example, by any one of various serial interfaces, various parallel interfaces, or a combination of these.

[0052] The external device 99 is, for example, a personal computer or a facsimile machine, and supplies print jobs, image data, etc. to the control unit 90 via the input / output interface 80 .

[0053] The control unit 90 includes a CPU (Central Processing Unit) 91, a RAM (Random Access Memory) 92, a ROM (Read Only Memory) 93, a storage unit 94, and the like.

[0054] The CPU 91 reads out various control programs and setting data stored in the ROM 93, stores them in the RAM 92, and executes the programs to perform various arithmetic processing. For example, the control unit 90 generates a drive signal for an image to be formed based on image data received from the input / output interface 80, and outputs the drive signal to the head 55.

[0055] The RAM 92 provides a working memory space for the CPU 91 and stores temporary data. The RAM 92 may include a non-volatile memory.

[0056] The ROM 93 stores various control programs and setting data executed by the CPU 91. Note that, instead of the ROM 93, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

[0057] The storage unit 94 stores print jobs and image data related to the print jobs input from the external device 99 via the input / output interface 80. As the storage unit 94, for example, a nonvolatile semiconductor memory (so-called flash memory) or an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may also be used in combination.

[0058] The control unit 90 is connected to the transport unit 10, supply unit 20, discharge unit 30, ink supply unit 40, drawing unit 50, reading unit 60, operation and display unit 70, input / output interface 80, heating unit 95, etc. The control unit 90 controls the overall operation of the inkjet printer 1. The transport unit 10, supply unit 20, discharge unit 30, ink supply unit 40, drawing unit 50, reading unit 60, operation and display unit 70, input / output interface 80, heating unit 95, etc. are controlled by the control unit 90 to execute predetermined processes.

[0059] The inkjet printer 1 having the above configuration supplies the recording medium M from the supply unit 20 to the conveying unit 10 under the control of the control unit 90, draws on the recording medium M conveyed to the conveying unit 10 using the drawing unit 50, and conveys the recording medium M with the image formed thereon to the discharge unit 30.

[0060] [Head (Inkjet Head) 55] Next, the configuration of the inkjet head (head 55) according to this embodiment will be described. The configuration described here is the configuration of a single head 55. Note that all heads 55 in the inkjet printer 1 may have the same configuration, or the inkjet printer 1 may include heads 55 with configurations different from those described below.

[0061] FIG. 4 is a perspective view showing the appearance of the head 55. As shown in FIG.

[0062] The head 55 includes a housing 101 and an exterior member 102 that fits to the housing 101 at its bottom, with the main components housed inside the housing 101 and the exterior member 102. The exterior member 102 is provided with an inlet 103a through which ink is supplied from the outside and outlets 103b and 103c through which ink is discharged to the outside. A manifold 56 connected to the inlet 103a is also provided inside the exterior member 102. The exterior member 102 is also provided with a plurality of mounting holes 104 for mounting the inkjet head 55 to the base of the carriage 51.

[0063] 5A and 5B are diagrams showing the main configuration of the head chip in head 55. Fig. 5A is a diagram showing the main configuration of a cross section along the short side of the head chip, and Fig. 5B is a diagram showing the main configuration of a cross section along the long side of the head chip. Fig. 6 is a diagram showing the planar configuration of the periphery of the nozzles in head 55.

[0064] The components housed inside the housing 101 and exterior member 102 of the head 55 include a head chip 110. As shown in Figures 5A and 5B, the head chip 110 is configured by stacking and bonding multiple substrates (a first substrate 111, a second substrate 112, and a third substrate 113). The first substrate 111, the second substrate 112, and the third substrate 113 serve as a lower layer, a middle layer, and an upper layer, respectively, during use.

[0065] The first substrate 111 is a nozzle plate. A plurality of nozzles 59 (ejection holes), which are holes that penetrate the first substrate 111 in the thickness direction (corresponding to the ink ejection direction, which is typically the vertical direction), are provided in a row along the longitudinal direction. In the illustrated example, the number of nozzles 59 is six per example, but the number does not have to be six.

[0066] The first substrate 111 is also provided with a plurality of individual circulation channels 111a that communicate with the plurality of nozzles 59, respectively. The plurality of individual circulation channels 111a are grooves that extend parallel to one another in the short direction of the head 55 from the most downstream portion of the individual supply channel 57 that communicates with the corresponding nozzle 59, and all of them communicate with the common circulation channel 112a.

[0067] The second substrate 112 is provided with a plurality of individual supply flow paths 57 arranged in a row along the longitudinal direction. The individual supply flow paths 57 are holes that penetrate the second substrate 112 in the thickness direction and communicate with corresponding nozzles 59. In the illustrated example, there are six nozzles 59 per row, and therefore there are six individual supply flow paths 57 per row. In the following description, when the six individual supply flow paths 57 are to be distinguished from one another, they will be referred to as individual supply flow paths 57-1, 57-2, 57-3, 57-4, 57-5, and 57-6, and when they are not to be distinguished from one another, they will simply be referred to as "individual supply flow paths 57." The larger the branch number of the reference symbol, the farther the individual supply flow paths 57-1, 57-2, 57-3, 57-4, 57-5, and 57-6 are located from the inlet (inlet 103a) of the manifold 56, i.e., downstream of the manifold 56.

[0068] Each of the multiple individual supply channels 57 communicates, at its most upstream portion, with a manifold 56 that functions as a common supply channel. The multiple individual supply channels 57 are separated by partition walls that include piezoelectric elements 58. The piezoelectric elements 58 are electrically connected to the head driver 54 by electrodes and wiring (not shown). The piezoelectric elements 58 are driven in response to a drive voltage signal applied from the head driver 54 via the electrodes and wiring, thereby repeatedly causing shear-mode displacements in the partition walls of the individual supply channels 57, thereby fluctuating the pressure of the ink, and causing ink to be ejected from the nozzles 59 in response to these pressure fluctuations. In other words, the head 55 according to this embodiment is an inkjet head that ejects shear-mode ink.

[0069] The second substrate 112 is, for example, a ceramic piezoelectric body (a member that deforms in response to the application of voltage). Examples of the piezoelectric body include PZT (lead zirconate titanate), lithium niobate, barium titanate, lead titanate, and lead metaniobate.

[0070] The second substrate 112 is provided with a common circulation channel 112a that communicates with all of the individual circulation channels 111a at their most downstream portions. The common circulation channel 112a is a groove that extends along the longitudinal direction of the head 55 on the rear surface of the second substrate 112. The most downstream portion of the common circulation channel 112a communicates with a vertical circulation channel 112c that is also provided on the second substrate 112. The vertical circulation channel 112c communicates with the outlet 103c, enabling the circulation of ink.

[0071] A manifold 56 is provided on the third substrate 113. The manifold 56 extends along the longitudinal direction of the head 55 and communicates with all of the multiple individual supply flow paths 57 at their most upstream portions. The manifold 56 is a groove provided on the back surface side of the third substrate 113. The third substrate 113 may be a substrate made of a resin such as polyimide, or may be a substrate made of a metal such as SUS.

[0072] Figure 7 is a diagram showing a schematic cross-sectional view of the main components of the first substrate 111 (nozzle plate) and the second substrate 112 (piezoelectric element 58) in the vicinity of the nozzle 59 (region 59a shown in Figure 5B) in the inkjet head 55 of this embodiment.

[0073] In this embodiment, first substrate 111 has a passivation film 111b, and its surface is covered with an underlayer 710. Second substrate 112 is bonded to first substrate 111 by a resin layer 720 disposed on one surface of the first substrate in contact with underlayer 710. In this embodiment, specific materials are used for underlayer 710 and resin layer 720. This material selection enhances alkali resistance and solvent resistance, making it possible to prevent a decrease in the adhesive strength between first substrate 111 and second substrate 112 even when alkaline ink or ink containing a high concentration of methylpyrrolidone is used.

[0074] A liquid-repellent layer 730 is formed on the surface of the first substrate 111 opposite the resin layer 720, on which ink is ejected and flies (hereinafter simply referred to as the "ejection-side surface" or the "other surface"). By providing the liquid-repellent layer 730, it is possible to prevent ink and foreign matter from adhering to the nozzle opening surface, and to suppress ink ejection defects caused by the adhesion of the ink and foreign matter. The liquid-repellent layer 730 can be a known liquid-repellent layer made of a silane coupling agent, a fluororesin, or the like. A silane coupling agent is preferred from the viewpoint of increasing the bonding strength with the underlayer 710 (described below) by forming a siloxane bond.

[0075] The first substrate 111 is a substrate containing a metal, and a passivation film 111b is formed on its surface. The passivation film 111b has the effect of increasing the alkali resistance of the substrate. The metal contained in the first substrate 111 is not limited as long as it can form the passivation film 111b, but may be iron (Fe), aluminum (Al), bismuth (Bi), chromium (Cr), indium (In), tin (Sn), niobium (Nb), nickel (Ni), tantalum (Ta), tungsten (W), zinc (Zn), or palladium (Pd). The passivation film 111b may contain these metals. Specifically, the first substrate 111 may be a substrate formed from a metal material such as iron (e.g., stainless steel (SUS)), aluminum, or nickel, preferably SUS.

[0076] The thickness of the first substrate 111 is not particularly limited, but can be set to 10 μm or more and 500 μm or less, and preferably 30 μm or more and 150 μm or less.

[0077] The alkali resistance of the passivation film 111b varies depending on the type of metal. The effect of suppressing a decrease in adhesive strength achieved by the configuration of this embodiment is particularly pronounced when a passivation film 111b with low alkali resistance is formed. From this perspective, the first substrate 111 preferably contains at least one element selected from the group consisting of chromium (Cr), iron (Fe), nickel (Ni), molybdenum (Mo), and palladium (Pd). For example, the first substrate can be a layer formed from stainless steel (SUS) or nickel containing these elements.

[0078] The underlayer 710 contains silicon (Si) and carbon (C). The underlayer preferably contains Si-C bonds. For example, the underlayer 710 can be a layer formed of silicon carbide (SiC). By providing the underlayer 710 containing Si and C on the bonding surface between the first substrate 111 and the second substrate 112, the alkali resistance and solvent resistance of these bonding surfaces can be improved. Furthermore, the underlayer 710 containing Si and C has good adhesion to the resin layer 720 formed from a material described below. Due to these effects, in this embodiment, the adhesive strength between the first substrate 111 and the second substrate 112 is unlikely to decrease even when alkaline ink or ink containing a high concentration of methylpyrrolidone is used.

[0079] The base layer 710 may cover at least the portion of the surface of the first substrate 111 (the surface of the passivation film 111b) to which the second substrate 112 is bonded via the resin layer 720. The base layer 710 may cover the entire surface of the first substrate 111 facing the second substrate 112. The base layer 710 may also cover the surface inside the hole of the nozzle 59. The base layer 710 may also cover the entire surface of the ejection side of the first substrate 111.

[0080] In particular, it is preferable that the base layer 710 continuously covers the surface of the first substrate 111 from the liquid-repellent layer 730 to the resin layer 720. In this region, the passivation film 111b of the first substrate 111 is exposed, and is prone to deterioration due to alkaline ink or ink containing a high concentration of methylpyrrolidone. By covering this region with the base layer 710, deterioration of the first substrate 111 due to ink can be suppressed. Preferably, the base layer 710 continuously covers the surface of the first substrate 111 facing the second substrate 112, the surface inside the hole of the nozzle 59, and the surface on the ejection side.

[0081] 8 is a diagram schematically illustrating a cross-sectional configuration of essential parts of the first substrate 111 (nozzle plate) and the second substrate 112 (piezoelectric element 58) in the vicinity of the nozzle 59 (region 59a shown in FIG. 5B ) in an inkjet head 55 according to a modified example of the present embodiment. As shown in FIG. 8 , the base layer 710 may be disposed so as to partially cover the surface of the first substrate 111 facing the second substrate 112, but also to cover the portion to which the second substrate 112 is bonded via the resin layer 720.

[0082] The underlayer 710 preferably has a maximum peak P of binding energy of the Si 2p orbital in the surface portion measured by X-ray photoelectron spectroscopy (XPS) of 99.6 eV or more and 101.9 eV or less. Specifically, in this embodiment, a Quantera SXM manufactured by ULVAC-PHI can be used as the XPS measurement device. Monochromated Al Kα radiation (1486.6 eV) is used as the X-ray source. Measurements are performed with a detection area of ​​100 μmφ, a take-off angle of 45°, and a detection depth set to a range of approximately 4 nm to 5 nm. Furthermore, PHI Multipak can be used as the analysis software.

[0083] The underlayer 710 preferably has a depth-wise distribution of oxygen (O) atoms measured by X-ray photoelectron spectroscopy (XPS) that is higher on the surface opposite the first substrate 111 and lower on the surface facing the first substrate 111. Distributing more oxygen atoms on the surface side of the underlayer 710 facilitates the formation of covalent bonds and hydrogen bonds with the liquid-repellent layer 730, thereby increasing the adhesive strength of the liquid-repellent layer 730. The oxygen (O) atomic number distribution on the surface opposite the first substrate 111 refers to the number of oxygen (O) atoms in a region of the underlayer 710 that is 5 nm deep from the surface facing the first substrate 111. The oxygen (O) atomic number distribution on the surface facing the first substrate 111 refers to the number of oxygen (O) atoms in a region of the underlayer 710 that is 5 nm deep from the surface facing the first substrate 111.

[0084] Furthermore, it is preferable that the oxygen (O) atom number distribution of the underlayer 710, as measured by X-ray photoelectron spectroscopy (XPS), is higher on one surface side where the resin layer 720 is disposed and becomes lower toward the ejection side surface (the other surface) opposite the resin layer 720 (for example, the atom number distribution inside the nozzle 59 becomes lower toward the ejection side surface (the other surface)). By distributing more oxygen atoms on the ejection side surface where the liquid-repellent layer 730 is disposed, covalent bonds and hydrogen bonds can be more easily formed with the liquid-repellent layer 730, and the adhesive strength of the liquid-repellent layer 730 can be increased.

[0085] Furthermore, it is preferable that the carbon (C) atom number distribution of the underlayer 710, as measured by X-ray photoelectron spectroscopy (XPS), is higher on the surface side facing the first substrate 111 and lower on the surface side opposite the first substrate 111. Reducing the number of carbon atoms on the surface side of the underlayer 710 makes it easier to form covalent bonds or hydrogen bonds with the liquid-repellent layer 730, and the adhesive strength of the liquid-repellent layer 730 can be increased.

[0086] The thickness of the underlayer 710 is preferably 1 nm or more and 1000 nm or less, more preferably 5 nm or more and 300 nm or less, and even more preferably 10 nm or more and 200 nm or less.

[0087] The thickness of the base layer 710 may vary depending on the location. For example, the thickness may be thicker around the periphery of the nozzle 59 (ejection hole) than in other locations. By increasing the thickness of the base layer 710 around the periphery of the nozzle 59 (ejection hole), which serves as the ink flow path, the ink resistance of the first substrate 111 can be further improved.

[0088] The resin layer 720 is a cured product of a resin composition containing an epoxy compound represented by general formula (I) and a polythiol compound having two or more thiol groups in the molecule.

[0089]

[0090] In general formula (I), R １ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ２ are independently a linking group represented by general formula (II), m is a number of 0.1 or more and less than 50, and L is independently an integer of 0 or more and 3 or less.

[0091]

[0092] In general formula (II), R ３ and R ４ are independently a hydrogen atom or a methyl group in which some or all of the hydrogen atoms may be substituted with fluorine atoms.

[0093] The epoxy compound represented by general formula (I) forms a three-dimensionally crosslinked polymer when cured. This polymer is difficult for ink to penetrate, so it is possible to form a resin layer 720 that is difficult to absorb ink and difficult to swell during use.

[0094] From the viewpoint of improving the ink resistance and heat resistance of the resin layer 720, the epoxy compound represented by general formula (I) is preferably an epoxy compound represented by general formula (I-1).

[0095]

[0096] In general formula (I-1), R １ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. m is a number of 0.1 or more and less than 50. L is independently an integer of 0 or more and less than 3.

[0097] The content of the epoxy compound represented by general formula (I) is preferably 10 parts by mass or more and 100 parts by mass or less, and more preferably 30 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the total amount of the epoxy compounds contained in the resin composition. When the content of the epoxy compound represented by general formula (I) is within this range, it is easy to achieve both heat resistance and chemical resistance of the resin layer 720.

[0098] The resin composition preferably further contains an epoxy compound represented by general formula (IV).

[0099]

[0100] In general formula (IV), R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0101] The content of the epoxy compound represented by general formula (IV) is preferably 10 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the total amount of the epoxy compounds contained in the resin composition. When the content of the epoxy compound represented by general formula (IV) is in this range, the ink resistance of the resin layer 720 is likely to be improved.

[0102] The resin composition preferably further contains an epoxy compound represented by general formula (V).

[0103]

[0104] In general formula (V), R １０ and R １１ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0105] The content of the epoxy compound represented by general formula (V) is preferably 5 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the total amount of the epoxy compounds contained in the resin composition. When the content of the epoxy compound represented by general formula (V) is within this range, the resin layer 720 is easily formed, and the adhesiveness of the resin layer 720 is easily increased.

[0106] In addition to these, the resin composition may contain various epoxy compounds depending on the purpose. Examples of other epoxy compounds include polyglycidyl ether compounds of mononuclear polyhydric phenol compounds including hydroquinone, resorcinol, pyrocatechol, and phloroglucinol, dihydroxynaphthalene, biphenol, methylene bisphenol (bisphenol F), methylenebis(ortho-cresol), ethylidene bisphenol, isopropylidene bisphenol (bisphenol A), isopropylidene bis(ortho-cresol), tetrabromobisphenol A, 1,3-bis(4-hydroxycumylbenzene), 1,4-bis(4-hydroxycumylbenzene), 1,1,3-tris(4-hydroxyphenyl)butane, 1,1,2,2-tetra(4-hydroxyphenyl)ethane, thiobisphenol, sulfonylbisphenol, oxybisphenol, and terpene phenol, ethylene glycol, propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol, glycerin, trim ... Polyglycidyl ethers of polyhydric alcohols, including tyrolpropane, pentaerythritol, sorbitol, and bisphenol A-ethylene oxide adducts, maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, trimer acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and endomethylenetetrahydrophthalic acid, etc. Examples of epoxy compounds include glycidyl esters of aliphatic, aromatic, or alicyclic polybasic acids or homopolymers or copolymers of glycidyl methacrylate, N,N-diglycidylaniline, bis(4-(N-methyl-N-glycidylamino)phenyl)methane, and diglycidyl orthotoluidine, vinylcyclohexene diepoxide, dicyclopentanediene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,These include epoxidized products of cyclic olefin compounds such as 4-epoxy-6-methylcyclohexylmethyl-6-methylcyclohexanecarboxylate and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, epoxidized conjugated diene polymers such as epoxidized polybutadiene and epoxidized styrene-butadiene copolymers, and heterocyclic compounds such as triglycidyl isocyanurate or their terminal isocyanates reacted to form prepolymers and internally crosslinked products, or products obtained by polymerizing these with polyvalent active hydrogen compounds (polyhydric phenols, polyamines, carbonyl group-containing compounds, polyphosphate esters, etc.).

[0107] In the resin composition, from the viewpoint of sufficiently enhancing the curability, the epoxy equivalent of the entire epoxy compounds is preferably 70 or more and 3,000 or less, and more preferably 90 or more and 2,000 or less.

[0108] The polythiol compound acts as a curing agent for the epoxy compound.

[0109] The polythiol compound is not limited as long as it has two or more thiol groups in the molecule. Examples of the polythiol compound include thiol compounds obtained by an esterification reaction of a polyol with a mercapto organic acid, such as trimethylolpropane tris(thioglycolate), pentaerythritol tetrakis(thioglycolate), ethylene glycol dithioglycolate, trimethylolpropane tris(β-thiopropionate), pentaerythritol tetrakis(β-thiopropionate), and dipentaerythritol poly(β-thiopropionate).

[0110] The polythiol compound may be an alkyl polythiol compound such as 1,4-butanedithiol, 1,6-hexaneedithiol, or 1,10-decanedithiol; a terminal thiol group-containing polyether; a terminal thiol group-containing polythioether; a thiol compound obtained by reacting an epoxy compound with hydrogen sulfide; or a thiol compound having terminal thiol groups obtained by reacting a polythiol compound with an epoxy compound. These polythiol compounds may be produced using a basic substance as a reaction catalyst. Therefore, it is preferable to reduce the alkali metal ion concentration to 50 ppm or less by a dealkalization treatment. The dealkalization treatment can be performed by dissolving the polythiol compound in an organic solvent such as acetone or methanol, neutralizing it with an acid such as dilute hydrochloric acid or dilute sulfuric acid, and removing the resulting salt by extraction, washing, or the like. Alternatively, the dealkalization treatment can be performed by adsorption removal using an ion exchange resin or separation and purification by distillation.

[0111] The polythiol compound is preferably dipentaerythritol hexa(3-mercaptobutyrate) or 1,3,5-tris(3-mercaptopropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, which tends to achieve both storage stability and curability.

[0112] The compounding ratio of the epoxy compound to the polythiol compound in the resin composition is preferably a ratio of thiol equivalents / epoxy equivalents of 0.2 to 2.0, more preferably 0.5 to 1.5. When the compounding ratio is 0.2 or more, the resin composition can be cured in a short time. When the compounding ratio is 2.0 or less, the heat resistance of the resin layer 720 is likely to be improved.

[0113] The resin composition may further contain an imidazole compound represented by general formula (III).

[0114] The imidazole compound acts as a curing accelerator or a base catalyst.

[0115]

[0116] In formula (III), k is an integer of 1 to 6, preferably 1 or 2. j is 0 or 1, preferably 1.

[0117] In general formula (III), R ５ , R ６ and R ７ are independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group.

[0118] Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a tert-pentyl group, a hexyl group, an isohexyl group, an octyl group, a 2-ethylhexyl group, a tert-octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group. Examples of the aryl group include a phenyl group and a naphthyl group. These functional groups may be substituted with a halogen, a hydroxy group, or the like.

[0119] R ５ , R ６ and R ７ are preferably independently any one of a hydrogen atom, a methyl group, an ethyl group, and a phenyl group.

[0120] In general formula (III), R ８ represents an alkylene group having 1 to 20 carbon atoms, an arylene group, and —CH ２ CH ２ COO-.

[0121] Examples of the alkylene group having 1 to 20 carbon atoms include a methylene group, an ethylene group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, an octane-1,8-diyl group, a 2-methyl-hexane-1,6-diyl group, and a decane-1,10-diyl group. Examples of the arylene group include a phenylene group and a naphthylene group. These linking groups may be substituted with a halogen, a hydroxy group, or the like.

[0122] R ８ is a methylene group or -CH ２ CH ２ It is preferably COO-.

[0123] In general formula (III), R ９ When k is 1, R is any one of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, and a cyanomethyl group. ９ When k is 2 or more and 6 or less, it is a hydrocarbon group having 1 or more and 20 or less carbon atoms.

[0124] Examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms, and an aryl group.

[0125] Examples of the alkyl group and aryl group having 1 to 20 carbon atoms include R ５ , R ６ , and R ７ The linking groups exemplified as:

[0126] Specific examples of the imidazole compound represented by general formula (III) include the following compounds:

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151] The content of the imidazole compound is not particularly limited. For example, the content of the imidazole compound can be 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the epoxy compound.

[0152] From the viewpoint of increasing the adhesive strength of the resin layer 720, the resin composition preferably contains a silane coupling agent represented by general formula (VI).

[0153]

[0154] In general formula (VI), R １２ and R １３ are independently alkyl groups having 1 to 4 carbon atoms.

[0155] Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group.

[0156] In general formula (VI), R １４ is an alkylene group having 1 to 20 carbon atoms or an arylene group.

[0157] Examples of the alkylene group having 1 to 20 carbon atoms include a methylene group, an ethylene group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, an octane-1,8-diyl group, a 2-methyl-hexane-1,6-diyl group, and a decane-1,10-diyl group. Examples of the arylene group include a phenylene group and a naphthylene group. These linking groups may be substituted with a halogen, a hydroxy group, or the like.

[0158] In general formula (VI), R １５ is either a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group.

[0159] In general formula (VI), h and i are integers whose sum is 3.

[0160] Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a tert-pentyl group, a hexyl group, an isohexyl group, an octyl group, a 2-ethylhexyl group, a tert-octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group. Examples of the aryl group include a phenyl group and a naphthyl group. These functional groups may be substituted with an aryl group, a heterocycle, an amine, an amide, an imine, a halogen, a hydroxy group, or the like.

[0161] Specific examples of the silane coupling agent represented by general formula (VI) include 3-aminopropyl-trimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)aminopropyltrimethoxysilane, N-(2-aminoethyl)aminopropylmethyldimethoxysilane, and 3-phenylaminopropyltrimethoxysilane.

[0162] The resin composition may contain a silane coupling agent other than the silane coupling agent represented by general formula (VI), a titanate-based coupling agent, or an aluminate-based coupling agent.

[0163] Examples of the other silane coupling agents include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, N-2(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2(aminoethyl)-3-aminopropyltrimethoxysilane, N-2(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, (1,3-dimethyl-butylidene)-propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N,N-bis(3-(trimethoxysilane) N-(2-(vinylbenzylamino)ethyl)-3-aminopropyltrimethoxysilane, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, 3-phenylaminopropyltrimethoxysilane, aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, N-(2-(vinylbenzylamino)ethyl)-3-aminopropyltrimethoxysilane hydrochloride, 1,2-ethanediamine, N-{3-(trimethoxysilyl)propyl}-N-{(ethenylphenyl)methyl} derivative hydrochloride, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, and 3-isocyanatopropyltriethoxysilane.

[0164] Examples of the titanate-based coupling agent and aluminate-based coupling agent include tetra-i-propoxytitanium, tetra-n-butoxytitanium, tetrakis(2-ethylhexyloxy)titanium, titanium-i-propoxyoctylene glycolate, di-i-propoxy bis(acetylacetonato)titanium, poly(di-i-propoxy oxytitanium), poly(di-n-butoxy oxytitanium), di-n-butoxy bis(triethanolaminato)titanium, diisopropoxy bis(triethanolamine)titanium, isopropyl tri(N-amidoethyl aminoethyl)titanate, and acetoalkoxyaluminum diisopropylate.

[0165] These coupling agents preferably have an epoxy group or an amine group, and among these, epoxy group coupling agents are preferred from the viewpoint of suppressing the progress of the reaction during storage.

[0166] The resin composition may contain other additives including other curing catalysts, reactive or non-reactive diluents (plasticizers) including monoglycidyl ethers, dioctyl phthalate, dibutyl phthalate, benzyl alcohol, and coal tar, fillers or pigments such as glass fiber, carbon fiber, cellulose, silica sand, cement, kaolin, clay, aluminum hydroxide, bentonite, talc, silica, finely divided silica, titanium dioxide, carbon black, graphite, iron oxide, and bitumen, lubricants such as candelilla wax, carnauba wax, Japan wax, ivory wax, beeswax, lanolin, spermaceti, montan wax, petroleum wax, fatty acid wax, fatty acid esters, fatty acid ethers, aromatic esters, and aromatic ethers, tackifying resins including xylene resins and petroleum resins, thickeners, thixotropic agents, antioxidants, light stabilizers, ultraviolet absorbers, flame retardants, antifoaming agents, rust inhibitors, colloidal silica, and colloidal alumina.

[0167] The resin layer 720 preferably has an average thickness of 0.3 μm or more and 10.0 μm or less, and more preferably 0.5 μm or more and 6.0 μm or less. The thinner the average thickness of the resin layer 720, the higher the adhesion reliability. The thicker the average thickness of the resin layer 720, the higher the initial strength. The average thickness of the resin layer 720 can be measured by embedding it in epoxy resin, exposing the cross section with a polishing machine, and observing it with a scanning electron microscope (SEM).

[0168] [Manufacturing Method of Head (Inkjet Head) 55] FIGS. 9A to 9D and FIGS. 10A to 10C are diagrams showing a part of a manufacturing method of the head 55. FIG.

[0169] 9A, a base material is prepared as a material for a first substrate 111 (nozzle plate) having a plurality of nozzles 59 (discharge holes). The base material contains the above-mentioned material, and a passivation film 111b is formed on the surface thereof.

[0170] 9B, ejection holes (nozzles 59) are formed in the substrate. The nozzles 59 may be formed by a known method suited to the material of the substrate, such as etching, laser processing, punching, or electroforming. In this manner, the first substrate 111, which is a nozzle plate, can be obtained.

[0171] Next, as shown in FIG. 9C , an underlayer 710 is formed on the surface of the first substrate 111. The underlayer 710 may be formed by evaporation, sputtering, atomic layer deposition, chemical vapor deposition (CVD), or the like. Of these, CVD is preferred because it is easy to form a layer containing silicon (Si) and carbon (C). For example, a underlayer 710 having Si-C bonds can be formed by CVD using silicon carbide or trimethoxysilane. The underlayer 710 is preferably formed by applying a material from the ejection side of the first substrate 111. At this time, the applied underlayer 710 material flows around via the nozzle 59. This allows the underlayer 710 to be formed on the surface of the second substrate 112 as well.

[0172] At this time, the portion where the underlayer 710 is formed can be adjusted by applying a mask to the surface of the first substrate 111 as necessary. In this embodiment, the underlayer 710 is formed so as to cover at least the portion of the surface of the first substrate 111 (the surface of the passivation film 111b) to which the second substrate 112 is bonded via the resin layer 720. In other words, the above-mentioned bonded portion is not masked. In this manner, as shown in FIG. 8 , the underlayer 710 can be formed so as to partially cover the surface of the first substrate 111 facing the second substrate 112, but to cover the portion to which the second substrate 112 is bonded via the resin layer 720. Note that it is preferable not to apply a mask to the surface between the liquid-repellent layer 730 and the resin layer 720 of the first substrate 111, and to form the underlayer 710 on the surface between these layers. It is more preferable not to apply a mask to the surface of the first substrate 111 at all, and to form the underlayer 710 on the entire surface of the first substrate 111.

[0173] After forming the underlayer 710, it is preferable to clean the surface of the first substrate 111 by a known method to remove foreign matter.

[0174] Next, as shown in FIG. 9D, a liquid-repellent layer 730 is formed on the surface of the first substrate 111 (the surface of the base layer 710).

[0175] Specifically, a plasma treatment in oxygen gas is performed to form OH groups on the surface of the base layer 710, thereby enhancing wettability. The first substrate 111 is then immersed in a liquid-repellent agent, which will be the material for the liquid-repellent layer 730. The liquid-repellent agent can be, for example, a solution prepared by diluting a silane coupling agent with a solvent such as water and further adding a surfactant or the like. Note that the method for applying the liquid-repellent agent is not limited to this. The liquid-repellent agent may be applied by CVD, spray coating, spin coating, or wire bar coating. The liquid-repellent layer 730 is then formed by a known method such as heat treatment. After forming the liquid-repellent layer 730, it is preferable to remove any remaining liquid-repellent agent by ultrasonic cleaning or the like.

[0176] Using a method such as immersion, a liquid-repellent layer 730 is formed on the entire surface (one surface and the other surface) of the first substrate 111, as shown in FIG. 9D . Then, the liquid-repellent layer 730 is removed from the first substrate 111, except for the ejection-side surface, by a plasma removal method or the like. For example, a mask may be applied to the portion of the ejection-side surface where the liquid-repellent layer 730 is to be left, and plasma etching may be performed using a mixed gas of CF4 and oxygen or oxygen gas. The flow rate may be 30 sccm or more and 300 sccm or less. The pressure may be 10 Pa or more and 70 Pa or less. The microwave output may be 100 W or more and 300 W or less. The processing time may be 10 seconds or more and 20 minutes or less.

[0177] In this way, a substrate having a liquid-repellent layer 730 formed on the surface on the ejection side as shown in FIG. 10A can be obtained.

[0178] This plasma etching can distribute more oxygen atoms on the surface side of the underlayer 710. Specifically, the oxygen (O) atomic number distribution in the depth direction of the underlayer 710 can be made greater on the surface side opposite the first substrate 111 and less on the first substrate 111 side. This plasma etching can also distribute more oxygen atoms on the discharge-side surface of the underlayer 710. This plasma etching can also distribute more oxygen atoms on the discharge-side surface of the underlayer 710 in the nozzle 59. The oxygen (O) atomic number distribution of the underlayer 710 in the nozzle 59 can be made greater on one surface side where the resin layer 720 is disposed and less toward the discharge-side surface (the other surface) opposite the resin layer 720.

[0179] Furthermore, this plasma etching can distribute more carbon atoms inside the underlayer 710. Specifically, the distribution of the number of carbon (C) atoms in the depth direction of the underlayer 710 can be made to be greater on the surface side facing the first substrate 111 and less on the surface side opposite the first substrate 111.

[0180] Next, as shown in FIG. 10B , a resin composition 720a (described above) that serves as the material for the resin layer 720 is applied to a portion of one surface of the first substrate 111 where the second substrate 112 (piezoelectric element 58) will be bonded. The resin composition 720a may be applied using a known method. Thereafter, as shown in FIG. 10C , the second substrate 112 is placed, and the resin composition 720a is cured using a known method, thereby bonding the second substrate 112 to the first substrate 111 via the resin layer 720. Alternatively, the resin composition 720a (described above) that serves as the material for the resin layer 720 may be applied using a known method to a portion of the surface of the second substrate 112 where the first substrate 111 will be bonded, and the resin composition 720a may be cured using a known method after the first substrate 111 is placed, thereby bonding the first substrate 111 to the second substrate 112 via the resin layer 720. Thereafter, another substrate may be bonded using a known method, thereby obtaining the head 55.

[0181] Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the specific embodiments described above. Various modifications and changes to the specific examples described in the above embodiments are possible within the scope of the gist of the present invention as defined in the claims.

[0182] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0183] 1. Fabrication of Inkjet Head Two types of nozzle plate materials were prepared: a stainless steel (SUS) substrate with a chromium (Cr)-containing oxide film (passive film) formed on its surface, and a nickel substrate with a nickel (Ni)-containing oxide film (passive film) formed on its surface.

[0184] 1-1. Inkjet head 1 An underlayer having a thickness of 108 nm was formed on a substrate made of SUS using a plasma CVD device (SAMCO plasma CVD device PD-200ST). The source gases were tetramethylsilane, Si(CH ３ ) ４ ) was used. Argon was used as the carrier gas. The flow rate of the material gas was 30 sccm, and the flow rate of the carrier gas was 10 sccm. The film formation temperature was 25°C. The RF power during film formation was 500 W.

[0185] The formed underlayer was subjected to XPS analysis under the following conditions, and the maximum peak P (eV) of the binding energy of the Si 2p orbital was found to be 100.4 (eV). XPS measurement device: Quantera SXM manufactured by ULVAC-PHI, X-ray source: monochromated Al Kα ray (1486.6 eV), detection area: 100 μmφ, take-off angle: 45°, detection depth: approximately 4 nm to 5 nm.

[0186] Thereafter, the substrate whose surface had been cleaned was immersed in a solution of a silane coupling compound (Optool DSX manufactured by Daikin Industries, Ltd., a silane group-terminated perfluoropolyether compound) HFE7200 (manufactured by 3M), and after removal, was left in the atmosphere (20 ° C, humidity 30%) for 12 hours, and then heated at 100 ° C for 60 minutes to form a liquid-repellent layer. Furthermore, a mask was applied to the ejection surface, and plasma etching was performed for 10 minutes with an oxygen gas flow rate of 50 sccm, a pressure of 20 Pa, and a microwave output of 200 W, to remove unnecessary portions of the liquid-repellent layer.

[0187] Thereafter, ejection holes were formed in these substrates by laser processing to form nozzle plates.

[0188] As the epoxy compound represented by general formula (I), 60 parts by mass of a phenol novolac epoxy resin (tri- or higher functional, jER Grade 152 (manufactured by Mitsubishi Chemical Corporation)) and 40 parts by mass of triglycidyl-p-aminophenol were prepared. As a polythiol compound having two or more thiol groups in the molecule, 102 parts by weight of trimethylolpropane tris(3-mercaptobutyrate) was prepared. As an imidazole compound represented by general formula (III), 2-ethyl-4-methylimidazole was prepared. As a coupling agent, 2 parts by mass of aminopropyltrimethoxysilane was prepared. These were mixed while cooling to obtain a resin composition.

[0189] After forming a base layer and cleaning the surface of the nozzle plate, a resin composition was applied to the area where the piezoelectric element was to be attached, to a thickness of 2.5 μm. A SUS304 base material (second substrate) was then brought into contact with the resin composition and heated to 80°C while applying a pressure of 10 cN m. After 3 hours, it was confirmed that the resin composition had hardened into a resin layer, and the second substrate was bonded to the nozzle plate.

[0190] The thus obtained bonded assembly of the nozzle plate and the second substrate was used as a simulated inkjet head 1.

[0191] After manufacturing the inkjet head 1, the nozzle plate was peeled off to remove the adhesive. Then, argon (Ar) was used as an etching ion species. ＋ The surface of the nozzle plate was etched by rare gas ion sputtering using a fluorine-containing ...

[0192] The XPS measurement results showed that the oxygen (O) atom number distribution in the depth direction within the underlayer was higher in a region 5 nm from the surface opposite the substrate (SUS) and lower in a region 5 nm from the surface on the substrate (SUS) side. Furthermore, the oxygen (O) atom number distribution in the underlayer was higher on one surface where the piezoelectric element and resin layer were located and lower on the surface on the ejection side where the liquid-repellent layer was located.

[0193] 1-2. Inkjet head 2 The underlayer is formed using silicon (Si) as a target and O as a reactive gas. ２ SiO formed by sputtering using ２ A simulated ink-jet head 2 was obtained in the same manner as the ink-jet head 1, except that a film was used.

[0194] When the underlayer was subjected to XPS analysis in the same manner as in inkjet head 1, the maximum peak P (eV) of the binding energy of the Si 2p orbital was not confirmed in the range of 99.6 (eV) to 101.9 (eV). In addition, the atomic number distribution of oxygen (O) in the depth direction within the underlayer did not change in the thickness direction, nor did it change on both sides of the nozzle plate.

[0195] 1-3. Inkjet Head 3 A simulated inkjet head 3 was obtained in the same manner as inkjet head 1, except that no undercoat layer was formed.

[0196] 1-4. Inkjet head 4 A simulated inkjet head 4 was obtained in the same manner as inkjet head 1, except that no undercoat layer was formed, no polythiol compound was contained, and the resin layer was formed using a resin composition containing 14 parts by mass of a modified aliphatic amine (jER Cure Grade TO184 (manufactured by Mitsubishi Chemical Corporation)), which is a polyamine, instead of an imidazole compound.

[0197] 1-5. Inkjet Head 5 A simulated inkjet head 5 was obtained in the same manner as inkjet head 1, except that a Ni substrate was used instead of the SUS substrate and the ejection holes were formed by electroforming.

[0198] XPS analysis of the underlayer was performed in the same manner as for inkjet head 1, and the maximum peak P (eV) of the binding energy of the Si 2p orbital was found to be 100.4 (eV). Furthermore, the oxygen (O) atom number distribution in the depth direction within the underlayer was higher in a region 5 nm from the surface opposite the substrate (SUS) and lower in a region 5 nm from the surface on the substrate (SUS) side. Furthermore, the oxygen (O) atom number distribution of the underlayer was higher on one surface side where the piezoelectric element and resin layer were disposed and lower on the surface side on the ejection side where the liquid-repellent layer was disposed.

[0199] 2. Evaluation The obtained simulated inkjet heads 1 to 5 were immersed in simulated ink.

[0200] The simulated ink was designated Ink 1, which contained 75% by mass of N-2-methylpyrrolidone and 25% by mass of 2-n-butoxyethyl acetate. Ink 1 simulates a strong solvent ink containing methylpyrrolidone. Ink 2 was an aqueous solution to which sodium bicarbonate and sodium carbonate were added to adjust the pH to 11. Ink 2 simulates an alkaline ink.

[0201] After immersion for a predetermined time, the presence or absence of peeling of the second substrate from the nozzle plate was checked to evaluate the ink resistance. The evaluation criteria are as follows: A: No peeling occurred even after immersion at 60°C for 4 weeks. B: No peeling occurred after immersion at 60°C for 1 week, but peeling occurred after immersion at 60°C for 4 weeks. C: Peeling occurred after immersion at 60°C for 1 week.

[0202] The results are shown in Table 1.

[0203]

[0204] As shown in Table 1, in an inkjet head in which the underlayer contains silicon (Si) and carbon (C) and the resin layer is a cured product of a resin composition containing an epoxy compound represented by general formula (I) and a polythiol compound having two or more thiol groups in the molecule, the adhesive strength between the nozzle plate and other members was less likely to decrease even when alkaline ink or ink containing methylpyrrolidone was used.

[0205] This application claims priority from Japanese Patent Application No. 2024-017974, filed February 8, 2024. The entire disclosures of the specification, claims and drawings of that application as originally filed are incorporated herein by reference.

[0206] The present invention is useful as an inkjet head and an inkjet recording apparatus that are highly durable even when alkaline ink or ink containing methylpyrrolidone is used.

[0207] REFERENCE SIGNS LIST 1 Inkjet printer 10 Conveying section 11 Conveying belt 11a Conveying surface 12 Driving roller 13 Driven roller 20 Supplying section 21 Supply stacking section 22 Supplying conveying section 30 Discharging section 31 Discharging stacking section 32 Discharging conveying section 40 Ink supplying section 41 Main tank 42 Flow path 50 Drawing section 51 Carriage 52a First sub-tank 52b Second sub-tank 53a, 53b, 53c Flow path 54 Head driving section 55 Inkjet head 56 Manifold (common supply flow path) 57 Individual supply flow path 58 Piezoelectric element 59 Nozzle 60 Reading section 70 Operation display section 80 Input / output interface 90 Control section 91 CPU 92 RAM 93 ROM 94 Storage section 95 Heating section 99 External device 101 Housing 102 Exterior member 103a Inlet 103b, 103c Outlet 104 Mounting hole 110 Head chip 111 First substrate 111a Individual circulation flow path 111b Passivation film 112 Second substrate 112a Common circulation flow path 112b Vertical circulation flow path 113 Third substrate 710 Underlayer 720 Resin layer 720a Resin composition 730 Liquid-repellent layer

Claims

1. a nozzle plate having a plurality of ejection holes, the nozzle plate having a substrate having a passivation film on its surface and an underlayer covering the surface; a resin layer disposed on one surface of the substrate in contact with the underlayer, the underlayer contains silicon (Si) and carbon (C); the resin layer is a cured product of a resin composition containing an epoxy compound represented by general formula (I) and a polythiol compound having two or more thiol groups in the molecule, An inkjet head, wherein the distribution of the number of oxygen (O) atoms in the depth direction of the underlayer measured by X-ray photoelectron spectroscopy is greater on the surface side opposite the substrate and less on the substrate side. 【Chemistry 1】 (In general formula (I), R １ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ２ are independently a linking group represented by general formula (II), m is a number of 0.1 or more and less than 50, and L is independently an integer of 0 or more and 3 or less. 【Chemistry 2】 (In general formula (II), R ３ and R ４ each independently represents a hydrogen atom or a methyl group in which some or all of the hydrogen atoms may be substituted with fluorine atoms.

2. The resin layer is a cured product of a resin composition further containing an imidazole compound represented by general formula (III).

2. The ink jet head according to claim 1. 【Transformation 3】 (In general formula (III), R ５ , R ６ and R ７ each independently represents an atom or a substituent selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group; R ８ each independently represents an alkylene group or an arylene group having 1 to 20 carbon atoms; R ９ When k is 1, it is an atom or a substituent selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, and a cyanomethyl group; when K is an integer of 2 to 6, it is a hydrocarbon group having 1 to 20 carbon atoms; j is 0 or 1, and k is an integer of 1 to 6.

3. The substrate contains at least one element selected from the group consisting of chromium (Cr), iron (Fe), nickel (Ni), molybdenum (Mo), and palladium (Pd); 2. The ink jet head according to claim 1.

4. the underlayer has a maximum peak P of binding energy of Si 2p orbital in a surface portion measured by X-ray photoelectron spectroscopy of 99.6 (eV) or more and 101.9 (eV) or less; 2. The ink jet head according to claim 1.

5. the underlayer has an oxygen (O) atom number distribution measured by X-ray photoelectron spectroscopy that is higher on one surface side on which the resin layer is disposed and lower toward the other surface opposite to the resin layer; 2. The ink jet head according to claim 1.

6. the nozzle plate has a liquid-repellent layer on the other surface opposite to the resin layer; 2. The ink jet head according to claim 1.

7. the underlayer continuously covers the surface of the substrate that forms the ejection holes, from the liquid-repellent layer to the resin layer; 7. The ink jet head according to claim 6.

8. preparing a substrate having a plurality of ejection holes and a passivation film formed on a surface thereof; forming an underlayer containing silicon (Si) and carbon (C) on a surface of the substrate; disposing a resin composition containing an epoxy compound represented by general formula (I) and a polythiol compound having two or more thiol groups in the molecule on one surface of the substrate in contact with the underlayer; curing the resin composition; forming a liquid-repellent layer on the surface of the substrate on which the underlayer has been formed; and removing the liquid-repellent layer from the one surface before placing the resin composition. The method for manufacturing an inkjet head includes the steps of: 【Chemistry 4】 (In general formula (I), R １ are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ２ are independently a linking group represented by general formula (II), m is a number of 0.1 or more and less than 50, and L is independently an integer of 0 or more and 3 or less. 【Transformation 5】 (In general formula (II), R ３ and R ４ each independently represents a hydrogen atom or a methyl group in which some or all of the hydrogen atoms may be substituted with fluorine atoms.

9. The liquid-repellent layer is removed by a plasma removal method. The method for manufacturing an ink jet head according to claim 8 .

10. The underlayer is formed by chemical vapor deposition. The method for manufacturing an ink jet head according to claim 8 .

11. An image forming apparatus comprising the inkjet head according to any one of claims 1 to 7.

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