Protective film, method for producing protective film, inkjet head, method for producing inkjet head, and inkjet-recording device

Abstract

Provided are a protective film having a uniform thickness and having improved heat resistance, and the like.　The protective film has a first organic layer, an inorganic layer, and a second organic layer in the stated order. The first organic layer and the second organic layer contain a polyparaxylene having a structure represented by general formula (1) or a derivative thereof, or a polyparaxylene derivative having a structure represented by general formula (2). At least one of the first organic layer and the second organic layer contains a polyparaxylene derivative having a structure represented by general formula (2).

Description

Protective film, method for manufacturing a protective film, inkjet head, method for manufacturing an inkjet head, and inkjet recording apparatus

[0001] The present invention relates to a protective film, a method for manufacturing a protective film, an inkjet head, a method for manufacturing an inkjet head, and an inkjet recording apparatus.

[0002] By providing a protective film containing an inorganic thin film and an organic thin film on the surface in contact with the ink, corrosion of the base material and other members can be suppressed (Patent Document 1).

[0003] International Publication No. 2022 / 244542

[0004] For example, the head chip of an inkjet head is manufactured by joining each member provided with an adhesive. In recent years, from the perspective of extending the product life, an adhesive with high durability against the solvent contained in the ink is used. Such an adhesive generally has a high curing temperature, and each member is exposed to a high temperature during joining. Therefore, the protective film provided on the surface of the flow path, that is, the surface in contact with the ink, is required to further improve its heat resistance.

[0005] In addition, the head chip of an inkjet head has a partially uneven structure or a plurality of different materials exposed on the surface of the flow path, making it difficult to form a protective film with a uniform thickness. It is difficult to obtain a sufficient protective function at the locations where the protective film is thin.

[0006] The problem to be solved by the present invention is to provide a protective film or the like having a uniform thickness and improved heat resistance.

[0007] The inventor of the present invention studied the causes of the above problems in order to solve the above problems. The protective film has a first organic layer, an inorganic layer, and a second organic layer in this order, and the first organic layer and the second organic layer contain a predetermined polyparaxylylene or a derivative thereof. As a result, it has been found that a protective film having a uniform thickness and improved heat resistance can be provided, leading to the present invention. That is, the above problems according to the present invention are solved by the following means.

[0008] 1. A protective film having a first organic layer, an inorganic layer, and a second organic layer in this order, wherein the first organic layer and the second organic layer contain poly(p - xylylene) or a derivative thereof having a structure represented by the following general formula (1), or a derivative of poly(p - xylylene) having a structure represented by the following general formula (2), and at least one of the first organic layer and the second organic layer contains a derivative of poly(p - xylylene) having a structure represented by the following general formula (2).

[0009]

[0010] In the general formula (1), a X1s each independently represent an alkyl group having 1 to 5 carbon atoms or a halogen atom. a represents an integer of 0 to 4. n1 represents the degree of polymerization.

[0011]

[0012] In the general formula (2), b X2s each independently represent an alkyl group having 1 to 5 carbon atoms or a halogen atom. b represents an integer of 0 to 4. n2 represents the degree of polymerization. c X3s each independently represent an alkyl group having 1 to 5 carbon atoms. c represents an integer of 0 to 3. d represents an integer of 1 to 4. n3 represents the degree of polymerization.

[0013] 2. The protective film according to item 1, wherein the second organic layer contains a derivative of poly(p - xylylene) having a structure represented by the general formula (2).

[0014] 3. The protective film according to item 1, wherein both the first organic layer and the second organic layer contain a derivative of poly(p - xylylene) having a structure represented by the general formula (2).

[0015] 4. The protective film according to item 1, wherein the thickness of the first organic layer is in the range of 0.1 to 10 μm.

[0016] 5. The protective film according to item 1, wherein the thickness of the second organic layer is in the range of 0.1 to 10 μm.

[0017] 6. The protective film according to item 1, wherein the thickness of the inorganic layer is in the range of 10 to 500 nm.

[0018] 7. The protective film according to paragraph 1, wherein the inorganic layer includes a film containing an oxide of aluminum, silicon, titanium, hafnium, or tantalum.

[0019] 8. A method for manufacturing a protective film according to any one of paragraphs 1 to 7, comprising: a first organic layer formation step of forming the first organic layer; an inorganic layer formation step of forming the inorganic layer on the formed first organic layer; and a second organic layer formation step of forming the second organic layer on the formed inorganic layer, wherein in the inorganic layer formation step, the inorganic layer is formed using chemical vapor deposition, sputtering, or atomic layer deposition.

[0020] 9. An inkjet head having a channel through which ink flows, a protective film according to any one of items 1 to 7 on the surface of the channel, the first organic layer located on the surface side of the channel and the second organic layer located on the side that comes into contact with the ink.

[0021] 10. The inkjet head according to paragraph 9, wherein the surface of the flow channel has an uneven structure.

[0022] 11. The inkjet head according to paragraph 9, wherein the surface of the flow channel exposes an adhesive and substrates of multiple different materials.

[0023] 12. The inkjet head according to paragraph 9, comprising an actuator, a flow channel substrate, and a nozzle substrate, wherein the actuator, the flow channel substrate, and the nozzle substrate are joined together with an adhesive.

[0024] 13. A method for manufacturing an inkjet head as described in paragraph 12, wherein the protective film is exposed to an environment of 80°C or higher.

[0025] 14. An inkjet recording device comprising the inkjet head described in paragraph 12.

[0026] According to the present invention, the thickness of the protective film can be made uniform, and its heat resistance can be improved. As a result, the protective film can protect the substrate for a long period of time.

[0027] The mechanism by which the effects of this invention manifest or the mechanism of action are presumed to be as follows.

[0028] Compared to inorganic films, organic films can be made less susceptible to the effects of the pH value of the liquid they come into contact with by selecting appropriate materials. Furthermore, inorganic films have higher water resistance than organic films. Therefore, protective films can be made more durable against the liquids they come into contact with by incorporating both organic and inorganic films.

[0029] Conventional protective films, particularly organic films within protective films, are prone to cracks and other defects within the protective film due to the breakdown of polymer molecular bonds caused by reactive oxygen species generated in high-temperature environments. Liquids can then penetrate the substrate through these cracks and other defects, leading to corrosion of the substrate and other components.

[0030] In this embodiment, the polymer contained in the protective film is a derivative of polyparaxylylene (PPX-NH) into which an amino group has been introduced. ２ ) is used. The mechanism is not clear, but PPX-NH ２ It is less prone to cracking and other defects even in high-temperature environments, and has high heat resistance. Therefore, it can protect the substrate over a long period of time.

[0031] Conventional protective films, particularly inorganic films within protective films, struggle to form uniformly thick, even films if the underlying layer on which the film is deposited is non-uniform. Specifically, if the surface of the underlying layer (the film-forming surface) is not flat but has an uneven structure, it is difficult to form an inorganic film of uniform thickness along that uneven structure. Furthermore, if multiple different materials are exposed on the surface of the underlying layer, it is difficult to form an inorganic film of uniform thickness.

[0032] In this embodiment, the protective film has at least three layers, with a first organic layer provided between the substrate and the inorganic layer. The first organic layer easily forms a film of uniform thickness even if the surface of the substrate is uneven, and the inorganic layer easily forms a film of uniform thickness on the first organic layer. In other words, by providing the first organic layer, it is easy to form an inorganic layer of uniform thickness. As a result, a protective film can be formed evenly on the substrate, and it is believed that the substrate can be protected for a long period of time.

[0033] This is a perspective view showing an example of an inkjet head. This is a cross-sectional view of an inkjet head. This is a partial cross-sectional view of an inkjet head. This is a cross-sectional view along line IV-IV in Figure 3. This is a schematic cross-sectional view showing an example of a laminate. This is a schematic cross-sectional view showing an example of a laminate. This is a flowchart explaining the manufacturing method of an inkjet head. This is a flowchart explaining the actuator manufacturing process. This is a flowchart explaining the protection process. This is a schematic diagram showing the general configuration of an inkjet recording device. This is a schematic diagram of the line head as seen from the conveyor belt side.

[0034] The protective film of the present invention comprises, in order, a first organic layer, an inorganic layer, and a second organic layer. The first organic layer and the second organic layer contain polyparaxylylene or a derivative thereof having the structure represented by the general formula (1) above, or a derivative of polyparaxylylene having the structure represented by the general formula (2) above. At least one of the first organic layer and the second organic layer contains a derivative of polyparaxylylene having the structure represented by the general formula (2) above. The protective film of the present invention is characterized by the above. This characteristic is a technical feature common to or corresponding to the following embodiments.

[0035] In this embodiment, it is preferable that the second organic layer contains a polyparaxylylene derivative having the structure represented by the general formula (2) above. As a result, the second organic layer on the side in contact with the liquid has heat resistance, so the effects of the liquid are less likely to extend to the inorganic layer and the first organic layer on the substrate side, and the substrate can be protected for a long period of time.

[0036] In this embodiment, it is preferable that both the first organic layer and the second organic layer contain a polyparaxylylene derivative having the structure represented by the general formula (2) described above. As a result, both organic layers have heat resistance, and the substrate can be protected over a long period of time.

[0037] In this embodiment, the thickness of the first organic layer is preferably in the range of 0.1 to 10 μm. This allows it to fully function as a protective film.

[0038] In this embodiment, the thickness of the second organic layer is preferably in the range of 0.1 to 10 μm. This allows it to fully function as a protective film.

[0039] In this embodiment, the thickness of the inorganic layer is preferably in the range of 10 to 500 nm. This allows the origin of any minute defects that occur in the inorganic layer to be filled in, and also improves durability.

[0040] In this embodiment, the inorganic layer preferably contains a film containing an oxide of aluminum, silicon, titanium, hafnium, or tantalum. This allows for the formation of a dense film.

[0041] The present invention provides a method for manufacturing a protective film, comprising: a first organic layer formation step of forming a first organic layer; an inorganic layer formation step of forming an inorganic layer on the formed first organic layer; and a second organic layer formation step of forming a second organic layer on the formed inorganic layer. In the inorganic layer formation step, the inorganic layer is formed using chemical vapor deposition, sputtering, or atomic layer deposition.

[0042] The inkjet head of the present invention has a channel through which ink flows. The surface of the channel has the protective film described above. The first organic layer is located on the surface side of the channel, and the second organic layer is located on the side that comes into contact with the ink. This extends the lifespan of the inkjet head.

[0043] In this embodiment, the surface of the flow channel may have an uneven structure. The protective film can be formed with a uniform thickness even on surfaces with an uneven structure, thereby extending the lifespan of the inkjet head.

[0044] In this embodiment, the surface of the flow path may have an adhesive and substrates made of multiple different materials exposed. The protective film can be formed with a uniform thickness even on the surface where the adhesive and substrates made of multiple different materials are exposed, thereby extending the lifespan of the inkjet head.

[0045] In this embodiment, the system comprises an actuator, a flow channel substrate, and a nozzle substrate, and it is preferable that the actuator, flow channel substrate, and nozzle substrate are joined together with an adhesive. Since the protective film has heat resistance, it is less likely to deteriorate even when exposed to high temperatures during joining, thereby extending the lifespan of the inkjet head.

[0046] In the inkjet head manufacturing method of the present invention, the protective film may be exposed to an environment of 80°C or higher. Even in this case, the lifespan of the inkjet head is sufficiently long.

[0047] The inkjet recording device of the present invention is equipped with the above-described inkjet head. This makes it possible to extend the lifespan of the inkjet recording device.

[0048] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the disclosed embodiments. That is, although the following description will focus on the case in which a protective film is provided in the flow path of an inkjet head, the use of the protective film is not limited to this.

[0049] [Inkjet Head] Figure 1 is a perspective view showing an example of an inkjet head 1 of this embodiment. Figure 2 is a partial cross-sectional view of the inkjet head 1. When recording on a recording medium, the bottom surface of the inkjet head and the recording surface of the recording medium are positioned opposite each other. Specifically, the recording medium is positioned so that its recording surface is located below the inkjet head and perpendicular to the direction in which the ink is ejected. Inkjet recording is performed as the recording medium is transported.

[0050] For convenience, in the following explanation, the direction in which ink is ejected from the inkjet head will be considered downwards, and the opposite direction will be considered upwards. Furthermore, the direction in which the recording medium is transported will be considered the front-to-back direction, and the direction perpendicular to the direction in which the recording medium is transported on the recording surface will be considered the left-to-right direction.

[0051] The inkjet head 1 comprises an actuator 30, a manifold (not shown), a flow path substrate 40, and a nozzle substrate 50, which are housed in a housing 6. A flexible substrate, a drive circuit board, etc. (not shown) are located above these, and these are covered by a cover member 7 attached to the housing 6.

[0052] The housing 6 is formed by die-casting using, for example, aluminum as the material. The housing 6 is, for example, elongated in the left-right direction. The bottom surface of the housing 6 has an opening so that the nozzle substrate 50 is exposed to the outside. The housing 6 has mounting holes 68 at both ends in the left-right direction for attaching the housing 6 to the printer body.

[0053] In the example shown in Figure 2, the actuator 30 is of the bend mode type. The nozzle substrate 50 has a nozzle 51 for ejecting ink to the outside of the inkjet head 1. The actuator 30, the flow path substrate 40, and the nozzle substrate 50 are each joined together via an adhesive layer 2.

[0054] In this embodiment, the "flow channel substrate" refers to a substrate that forms a flow channel through which ink flows, and is located between the actuator 30 and the nozzle substrate 50. The flow channel substrate 40 is provided with a supply channel 21, a supply-side communication channel 23, and a nozzle-side communication channel 24. The supply-side communication channel 23 extends from the top of the supply channel 21 and is connected to the pressure chamber 22. The nozzle-side communication channel 24 penetrates the flow channel substrate 40 to connect the pressure chamber 22 and the nozzle 51 of the nozzle substrate 50.

[0055] The material of the flow channel substrate 40 is not particularly limited, but examples include glass, ceramic, silicon, plastic, stainless steel, etc.

[0056] The nozzle substrate 50 has a nozzle 51 that penetrates the nozzle substrate 50 at a position corresponding to the nozzle-side communication channel 24 extending from the lower part of the pressure chamber 22. The nozzle 51 has a shape in which the diameter gradually decreases as it extends downward, and the diameter is uniform near the outlet. The material of the nozzle substrate 50 is not particularly limited, but examples include silicon, polyimide, stainless steel, etc.

[0057] The actuator 30 has a pressure chamber layer 31 that forms a pressure chamber 22, and a diaphragm 32, an insulating layer 33, a piezoelectric layer 34, and an electrode layer 35 are laminated on top of the pressure chamber layer 31. The diaphragm 32, insulating layer 33, piezoelectric layer 34, and electrode layer 35 can be formed by a vacuum deposition method such as sputtering. These layers may also be formed by other deposition methods such as coating.

[0058] The pressure chamber layer 31 can be formed by a thick film formation method such as plating or by an etching method for a metal plate. The pressure chamber 22 is formed when the flow channel substrate 40 is joined to the lower surface of the pressure chamber layer 31. Examples of known metal materials for the pressure chamber layer 31 include nickel (Ni).

[0059] The diaphragm 32 contains a conductive metallic material and also serves as the lower electrode (common electrode) of the piezoelectric layer 34. Examples of known metallic materials for the diaphragm 32 include nickel (Ni).

[0060] The insulating layer 33 insulates the diaphragm 32 from the piezoelectric layer 34. In other words, the insulating layer 33 shields the application of voltage to the piezoelectric layer 34 outside the piezoelectric functional region R1.

[0061] The piezoelectric layer 34 preferably contains a perovskite-type compound. Examples of perovskite-type compounds include barium titanate (BaTiO2). ３ ), lead zirconate titanate (PZT: Pb(Zr・Ti)O ３ Examples include the above, and among them, it is preferable that it contains PZT as the main component. The molar ratio of Zr and Ti in PZT is preferably in the range of Zr / Ti = 30 / 70 to 70 / 30. Here, "main component" means that it is contained in an amount of 85% by mass or more of the total mass of the piezoelectric material.

[0062] To improve the performance of the piezoelectric material, donor ions may be added to the PZT. Examples of donor ions include metal ions such as lanthanum (La), niobium (Nb), tantalum (Ta), tungsten (W), aluminum (Al), and strontium (Sr). In particular, it is preferable that the donor ion be one or more metal ions selected from the group including La, Nb, Ta, and W. Furthermore, it is preferable that the thickness of the piezoelectric layer 34 be about a few μm.

[0063] The electrode layer 35 contains a conductive material. For example, the electrode layer 35 contains titanium, which is a precious metal. The thickness of the electrode layer 35 is approximately 0.2 μm.

[0064] When a voltage is applied to the electrode layer 35, the piezoelectric layer 34 deforms downward in the piezoelectric functional region R1, and consequently, the diaphragm 32 deforms. When the diaphragm 32 deforms downward in the piezoelectric functional region R1, the volume of the pressure chamber 22 decreases, and the pressure of the ink 60 filled in the pressure chamber 22 increases. Conversely, when the diaphragm 32 deforms upward in the piezoelectric functional region R1, the volume of the pressure chamber 22 increases, and the pressure of the ink 60 filled in the pressure chamber 22 decreases. By varying the pressure of the ink 60 in a predetermined sequence, for example, by reducing the pressure and then increasing it, droplets 61 of ink 60 are discharged from the nozzle 51, which communicates with the pressure chamber 22 via the nozzle-side communication channel 24.

[0065] The pressure chamber layer 31, diaphragm 32, insulating layer 33, piezoelectric layer 34, and electrode layer 35 do not necessarily have to be single layers, but may each be multiple layers. Furthermore, other layers may be positioned between each layer.

[0066] The thickness of the adhesive layer 2 is preferably in the range of 0.1 to 5 μm.

[0067] The adhesive used to form the adhesive layer 2 is not particularly limited as long as it is an adhesive that can bond the actuator 30, the flow channel substrate 40, and the nozzle substrate 50, respectively. Examples of adhesives include room-temperature curing adhesives that cure at room temperature, thermosetting adhesives that cure by accelerating polymerization through heating, and active energy ray curing adhesives that cure by accelerating polymerization through irradiation with active energy rays such as ultraviolet rays.

[0068] In particular, a thermosetting adhesive is preferred. Thermosetting adhesives generally have strong resistance to solvents contained in inks and do not deteriorate easily even when in contact with ink. Furthermore, when a thermosetting adhesive is heated to a predetermined temperature for curing after bonding, the viscosity of the adhesive temporarily decreases, making it more fluid and easier to obtain a uniform thickness of the resulting adhesive layer. Examples of thermosetting adhesives include epoxy adhesives containing epoxy resin and fluororesin adhesives containing fluororesin. In addition, a conductive adhesive may be used from the viewpoint of good electrical connection. Examples of conductive adhesives include adhesives in which conductive particles are dispersed.

[0069] In this embodiment, the "surface of the flow path" refers to the surface of the actuator 30, the flow path substrate 40, and the nozzle substrate 50 that comes into contact with the ink. Specifically, it refers to the outer circumferential surface of the supply flow path 21, the pressure chamber 22, the supply-side communication flow path 23, the nozzle-side communication flow path 24, and the nozzle 51. As shown in Figure 2, the width of the flow path through which the ink flows is not uniform, and the surface of the flow path has numerous irregularities such as corners, edges, and steps. The inkjet head 1 is provided with a protective film 4 on the surface of this flow path. In Figure 2, the protective film 4 is provided on only a portion of the surface of the flow path, but the protective film 4 may be provided on the entire surface of the flow path. The actuator 30 and the flow path substrate 40 each have minute irregularities, corners, edges, etc., on the surface of the flow path even when used individually. Therefore, as shown in Figure 2, the effects of the present invention can be fully obtained even if the protective film 4 is provided only on the surface of the flow path of the actuator 30 alone. Alternatively, the protective film 4 may be provided from the surface of the flow path of the actuator 30 to the surface of the flow path of the flow path substrate 40. In this case, the joint between the actuator 30 and the flow path substrate 40 is a joint where multiple different materials are joined via the adhesive layer 2, and the effects of the present invention can be obtained more significantly.

[0070] Figure 3 is a partial cross-sectional view of the inkjet head 1. In the example shown in Figure 3, the actuator 30 is of the shear mode type. The actuator 30 and the nozzle substrate 50 are joined via an adhesive layer 2. Although not shown in Figure 3, a flow channel substrate 40 may be provided between the actuator 30 and the nozzle substrate 50.

[0071] The actuator 30 has a pressure chamber layer 31 that forms a drive channel (pressure chamber) 11 and a dummy channel 12. The partition wall between the drive channel 11 and the dummy channel 12 is a drive wall 13 containing a piezoelectric material. Preferably, the piezoelectric material contains the same compound as that used in the bend-mode type.

[0072] The drive channel 11 and the dummy channel 12 penetrate the pressure chamber layer 31, and the drive channel 11 is connected to the nozzle 51 of the nozzle substrate 50. The nozzle substrate 50 has a nozzle 51 at a position corresponding to the drive channel 11. The nozzle substrate 50 does not have a nozzle 51 at a position corresponding to the dummy channel 12, and therefore the lower opening of the dummy channel 12 is blocked by the nozzle substrate 50. During ink ejection, ink flows through the drive channel 11 in the direction of the arrow, but no ink flows through the dummy channel 12. The dummy channel 12 is usually filled with a gas such as air.

[0073] Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 3. As shown in Figure 4, the drive electrodes 14 are located on the surfaces of the four walls facing into the drive channel 11 and the dummy channel 12. The actuator 30 is provided with protective films 4 on the four walls of the drive electrodes 14 that come into contact with the ink. In Figures 3 and 4, the drive electrodes 14 in the drive channel 11 are provided with protective films 4 on the four walls that come into contact with the ink, but the drive electrodes 14 in the dummy channel 12 may also be provided with protective films 4. In the dummy channel 12, the protective films 4 protect the drive electrodes 14 from moisture contained in gases such as air.

[0074] On the upper surface of the pressure chamber layer 31, connecting electrodes 15 are positioned so as to correspond one-to-one with the drive channels 11 and dummy channels 12. One end of each connecting electrode 15 is electrically connected to the drive electrode 14 in the corresponding drive channel 11 or dummy channel 12.

[0075] The actuator 30 shown in Figures 3 and 4 is an independently driven actuator in which drive channels 11 and dummy channels 12 are alternately positioned in each channel row of the pressure chamber layer 31. The actuator 30 deforms the drive wall 13 by shearing it by applying a drive signal of a predetermined voltage to the drive electrode 14. As a result, the pressure in the ink supplied into the drive channel 11 changes, and ink droplets are ejected from the nozzle 51 of the nozzle substrate 50.

[0076] The driving electrode 14 and the connecting electrode 15 contain a conductive material. Examples of conductive materials include platinum (Pt), gold (Au), copper (Cu), palladium (Pd), ruthenium (Ru), titanium (Ti), nickel (Ni), aluminum (Al), chromium (Cr), tungsten (W), and iridium (Ir). These may be included individually or in combination of two or more. The conductive material may be a mixture of metals or an alloy. In that case, it may be a mixture or alloy of at least one of the above metals with other metals.

[0077] The thickness of the adhesive layer 2 is preferably in the range of 0.1 to 5 μm. The adhesive used to form the adhesive layer 2 is not particularly limited, and the same adhesive as that used for the bend-mode type can be used.

[0078] (Protective Film) Figures 5 and 6 are schematic cross-sectional views showing an example of a laminate 70. The laminate 70 has a protective film 4 on a substrate 71. The protective film 4 mainly protects the substrate 71 from ink, but may also protect the substrate 71 from the outside air, etc. The protective film 4 comprises at least a first organic layer 41, an inorganic layer 42, and a second organic layer 43 from the substrate 71 side. The protective film 4 may have layers other than the first organic layer 41, the inorganic layer 42, and the second organic layer 43. For example, as shown in Figure 6, there may be a fourth layer 44 between the substrate 71 and the first organic layer 41, or a fifth layer 45 on the surface side of the second organic layer. Although not shown, there may also be other layers between the first organic layer, the inorganic layer, and the second organic layer.

[0079] As described above, in bend mode, protective films 4 are provided on the pressure chamber layer 31 and on the diaphragm 32. In this case, the pressure chamber layer 31, diaphragm 32, flow path substrate 40, and nozzle substrate 50 correspond to the base material 71 in the laminate 70. In shear mode, a drive electrode 14 is provided on the pressure chamber layer 31, and a protective film 4 is further provided on the drive electrode 14. In this case, the drive electrode 14 corresponds to the base material 71 in the laminate 70.

[0080] In the manufacturing of an inkjet head, it is preferable that the actuator 30, the flow channel substrate 40, and the nozzle substrate 50 are joined together with an adhesive after they have been manufactured. This allows suitable materials to be used for each part and simplifies the manufacturing process. The actuator 30, the flow channel substrate 40, and the nozzle substrate 50 may be joined together with an adhesive after a protective film 4 is formed on each of them, or the protective film 4 may be formed on the surface of the formed flow channels after they have been joined with an adhesive.

[0081] In the method of bonding with an adhesive after forming the protective film 4, the protective film 4 is exposed to a high-temperature environment (the curing temperature of the adhesive). Therefore, the protective film 4 needs to have heat resistance so that microcracks do not occur even when exposed to a high-temperature environment of, for example, about 80°C. In the method of forming the protective film 4 after bonding with an adhesive, the protective film 4 is formed on a surface where the adhesive and substrates of multiple different materials are exposed. Therefore, it is necessary to form a protective film 4 of uniform thickness on the surface of a channel made of different materials that is not partially planar.

[0082] Furthermore, when using an inkjet head, the ink may be heated to a relatively high temperature to improve ejection performance, in which case the protective film 4 is exposed to a high-temperature environment. Also, when attaching the chip obtained by joining the actuator 30, the flow path substrate 40, and the nozzle substrate 50 into the housing 6, adhesive may be used. In this case as well, the protective film 4 is exposed to a high-temperature environment. Therefore, regardless of the method of manufacturing the inkjet head, it is preferable that the protective film 4 has heat resistance so that microcracks and the like do not occur even when exposed to a high-temperature environment of, for example, about 80°C.

[0083] The overall thickness of the protective film 4 is not particularly limited, but is preferably in the range of 0.2 to 20 μm, more preferably in the range of 0.5 to 15 μm, and even more preferably in the range of 1 to 10 μm. Having a certain thickness allows the protective film to fully perform its function. Also, not being too thick does not hinder the deformation of the diaphragm 32 in the bend mode or the deformation of the drive wall 13 in the shear mode. The thickness can be controlled by adjusting the film formation conditions and the amount of raw material added in each layer.

[0084] The organic and inorganic layers constituting the protective film 4 will be described in order below.

[0085] (1) The first organic layer and the second organic layer will be described together below. The organic layer contains polyparaxylylene or its derivative having the structure represented by the following general formula (1), or a polyparaxylylene derivative having the structure represented by the following general formula (2). At least one of the first organic layer and the second organic layer contains a polyparaxylylene derivative having the structure represented by the following general formula (2). In this specification, polyparaxylylene or its derivative having the structure represented by the following general formula (1) is referred to as "PPX", and a polyparaxylylene derivative having the structure represented by the following general formula (2) is referred to as "PPX-NH ２ It is also called "PPX-NH". In this embodiment, "PPX" is "PPX-NH ２ " is not included.

[0086]

[0087] In general formula (1), each of the a X1 atoms independently represents an alkyl group having 1 to 5 carbon atoms, or a halogen atom. a represents an integer from 0 to 4. n1 represents the polymerization number.

[0088] Alkyl groups may be linear or branched. Examples of C1-C5 alkyl groups include methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl, secondary butyl, tert-butyl, isopentyl, neopentyl, and tert-pentyl groups. Examples of halogen atoms include fluorine, chlorine, and bromine.

[0089] In this embodiment, PPX is synthesized using 99 parts by mass or more of a paraxylylene compound that does not have an amino group, when the total amount of raw materials is 100 parts by mass.

[0090] A specific example of PPX is shown. n1 represents the polymerization number.

[0091]

[0092]

[0093] In general formula (2), each of the b X2 atoms independently represents an alkyl group having 1 to 5 carbon atoms, or a halogen atom. b is an integer from 0 to 4. n2 represents the number of polymerization units. Each of the c X3 atoms independently represents an alkyl group having 1 to 5 carbon atoms. c is an integer from 0 to 3. d is an integer from 1 to 4. n3 represents the number of polymerization units.

[0094] Alkyl groups may be linear or branched. Examples of C1-C5 alkyl groups include methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl, secondary butyl, tert-butyl, isopentyl, neopentyl, and tert-pentyl groups. Examples of halogen atoms include fluorine, chlorine, and bromine.

[0095] The sequence of repeating structures is not particularly restricted. PPX-NH ２ This may be any of the following: random copolymer, alternating copolymer, block copolymer, or Kraft copolymer.

[0096] In this embodiment, PPX-NH ２ is synthesized using 1 part by mass or more of a p-xylene compound having an amino group when the total amount of raw materials is 100 parts by mass. For example, in a certain polymer, if the amount of the p-xylene compound having no amino group exceeds 99 parts by mass and the amount of the p-xylene compound having an amino group is less than 1 part by mass, the polymer does not correspond to PPX-NH ２ and is regarded as corresponding to PPX.

[0097] PPX-NH ２ In the case where the total amount of raw materials is 100 parts by mass, the amount of the p-xylene compound having an amino group used is preferably in the range of 1 to 20 parts by mass, and more preferably in the range of 2 to 10 parts by mass. By synthesizing at this ratio, the formed film has good heat resistance. That is, in terms of the polymerization number, n2 / n3 is preferably in the range of 80 / 20 to 99 / 1, and more preferably in the range of 90 / 10 to 98 / 2.

[0098] PPX-NH ２ Specific examples are shown. n21, n22 and n3 represent the polymerization number. In the repeating structure having no amino group, in the specific example, a structure in which a hydrogen atom of the benzene ring is substituted with a chlorine atom and a structure in which the hydrogen atom is not substituted are shown, but the structure in which the hydrogen atom of the benzene ring is not substituted does not necessarily have to be present.

[0099]

[0100] The organic layer may contain any resin or the like in addition to PPX or PPX-NH ２ .

[0101] Thin films containing PPX can be formed by chemical vapor deposition (CVD), also known as CVD, using polyparaxylylene or its derivative dimer (solid) as the deposition source. In chemical vapor deposition, when the dimer is heated under vacuum, it sublimes into a dimer gas. This gas decomposes thermally, causing the dimer to cleave and become monomers. In a deposition chamber at room temperature, this monomer gas polymerizes on all surfaces, forming a transparent thin film. Chemical vapor deposition makes it easy to form a uniform thin film without unevenness because the monomer gas can penetrate and polymerize even in narrow areas.

[0102] Specifically, a thin film is formed according to the following chemical reaction equation. Formula (I) below shows the chemical structure of dimer (I) of paraxylylene or its derivative. Hereinafter, paraxylylene or its derivative will also be referred to as "paraxylylene compound (A)".

[0103] The following formula (II) shows the diradical of the stable paraxylylene compound (A) generated by sublimation and thermal decomposition of the dimer (I), and the chemical structure of the paraxylylene compound (A). Formula (II) shows the state in which the diradical of the paraxylylene compound (A) and the paraxylylene compound (A) coexist reversibly.

[0104] Formula (III) below shows the chemical structure of polymer (III) of paraxylylene compound (A), which is obtained by the adsorption and polymerization of the diradicals of paraxylylene compound (A) onto a substrate. Polymer (III) is formed as a film on the substrate.

[0105] In the CVD process, diradicals of stable paraxylylene compound (A) are generated by sublimation and thermal decomposition of dimer (I). The diradicals of paraxylylene compound (A) are preferable because they have excellent penetration into fine structures and penetrate sufficiently and uniformly deep into the microstructure of the substrate.

[0106]

[0107] In the above formulas (I), (II), and (III), X1 and a are the same as X1 and a in the above general formula (1).

[0108] PPX-NH２ Thin films containing PPX can be prepared using the same procedure as thin films containing PPX.

[0109] The organic layer may be oxidized on its surface, i.e., the surface facing the channel. Methods of oxidation include laser irradiation, UV / ozone treatment, and plasma irradiation. Among these, plasma irradiation is preferred. Oxidation introduces hydrophilic groups such as carboxyl groups and hydroxyl groups to the surface of the first organic layer, uniformly increasing the critical surface tension of the film. Furthermore, minute irregularities can be introduced to the surface of the first organic layer. This improves the adhesion between the first organic layer and the inorganic layer, thereby improving the durability of the substrate and the yield during manufacturing. Note that these irregularities are extremely minute and do not significantly affect the uniform layer formation of the inorganic layer.

[0110] From the perspective of improving heat resistance, both the first and second organic layers are made of PPX-NH ２ It is preferable that it contains. However, from the viewpoint of improving adhesion between the substrate and the protective layer, the first organic layer is PPX and the second organic layer is PPX-NH ２ That is also acceptable.

[0111] The thickness of the organic layer is preferably in the range of 0.1 to 10 μm. Having a certain thickness allows it to fully function as a protective film. Also, not being too thick does not hinder the deformation of the diaphragm in the bend mode or the deformation of the drive wall in the shear mode. The thickness can be controlled by adjusting the film formation conditions and the amount of raw material added.

[0112] (2) Inorganic layer The inorganic layer contains inorganic compounds as its main component. Here, "main component" means that it is present in an amount of 85% by mass or more of the total mass of the inorganic layer. The inorganic compound content is preferably 90% by mass or more, and more preferably 95% by mass or more, of the total mass of the inorganic layer.

[0113] The type of inorganic compound is not limited, but it is preferable that it is an inorganic compound that can form a dense inorganic thin film. This suppresses the occurrence of thickness variations and defects, and makes the thickness of the inorganic layer uniform.

[0114] Methods for forming the inorganic layer include chemical vapor deposition (CVD), sputtering, molecular layer deposition (MLD), and atomic layer deposition (ALD). From the viewpoint of enabling low-temperature film formation and the density of the resulting film, the inorganic layer is preferably formed by chemical vapor deposition (CVD), sputtering, or atomic layer deposition (ALD). Furthermore, atomic layer deposition (ALD) allows inorganic compounds to be supplied around complex structures, enabling the formation of a layer of uniform thickness.

[0115] Examples of inorganic compounds include metal oxides, metal nitrides, metal carbides, and allotropes of carbon. Examples of allotropes of carbon include diamond-like carbon (DLC). The inorganic compound is preferably a metal oxide, and examples include oxides of aluminum, silicon, titanium, hafnium, magnesium, zirconium, or tantalum. Among these, oxides of aluminum, silicon, titanium, hafnium, or tantalum are preferred. Specific examples of metal oxides include Al ２ O ３ SiO ２ , TiO ２ , HfO ２ MgO, ZrO ２ Ta ２ O ５ These are some examples.

[0116] The metal oxide may be a composite oxide of two or more metals selected from the above metals. Furthermore, the inorganic layer may contain a mixture of multiple metal oxides.

[0117] In the formation of an inorganic layer by atomic layer deposition (ALD), a precursor is first sublimated and adsorbed onto the lower layer surface. Here, "lower layer" refers to the substrate layer adjacent to the inorganic layer, which in the example shown in Figures 5 and 6 corresponds to the first organic layer 41. Next, the inorganic layer is formed by exposing the precursor to an oxidizing gas. The deposition of the inorganic layer is carried out in a vacuum chamber.

[0118] For example, Al ２ O ３Precursors include trimethylaluminum (TMA), dimethylaluminum isopropoxide (DMAIP), and dimethylaluminum hydride (DMAH). ２ As a precursor, tetraethoxysilane (TEOS; Si(OC) ２ H ５ ) ４ ), hexamethyldisilazane (HMDS; (CH ３ ) ３ Si-NH-Si(CH ３ ) ３ ) are some examples. TiO ２ As a precursor, tetrakis(dimethylamino)titanium (TDMAT; Ti[N(CH ３ ) ２ ] ４ ), TiCl ４ These are some examples.

[0119] HfO ２ The precursor is tetrakis(ethylmethylamide)hafnium(TEMAH; Hf[N(CH) ３ ) (C ２ H ５ )] ４ Examples include ZrO ２ As a precursor, tetrakis(ethylmethylamide)zirconium (TEMAZ; Zr[N(CH ３ ) (C ２ H ５ )] ４ Examples include: Ta ２ O ５ As a precursor, tetrachlorotantalum (TaCl ４ Examples include:

[0120] Examples of oxidizing agents include water (H ２ O), ozone (O ３ ), O ２ Plasma and similar technologies are used.

[0121] In the formation of inorganic layers by atomic layer deposition (ALD), one cycle consists of the adsorption of a precursor and the oxidation of the precursor by an oxidizing agent. The thickness of the inorganic layer can be adjusted by repeating this cycle. The inorganic layer formed in one cycle is usually at the monolayer level.

[0122] The formation of the inorganic layer by sputtering is not particularly limited, and known methods can be applied.

[0123] The inorganic layer may be a single layer or a multilayer film. For example, Al ２ O ３ SiO ２ , TiO ２ , HfO ２ and Ta ２ O ５ Examples include films made by stacking single-layer films of metal oxides selected from the above. In multilayer films, the number of layers is not particularly limited. In a multilayer film, for example, layers for improving adhesion and layers that are less prone to generating minute defects and have high barrier properties may be stacked alternately.

[0124] The thickness of the inorganic layer is preferably in the range of 10 to 500 nm, and more preferably in the range of 20 to 100 nm, from the viewpoint of filling in the starting points of minute defects and durability. If the inorganic layer is a multilayer film, it is preferable to adjust the thickness of each film so that the total thickness of the multilayer film falls within the above range.

[0125] [Method for Manufacturing an Inkjet Head] Figure 7 is a flowchart illustrating the method for manufacturing an inkjet head. This manufacturing method involves forming a protective film on the surface of the flow path that comes into contact with the ink only in the actuator, and then joining the actuator, the flow path substrate, and the nozzle substrate with an adhesive.

[0126] First, the actuator, nozzle substrate, and flow path substrate are manufactured (steps S1 to S3). Next, the nozzle substrate and the flow path substrate are joined together (step S4). Finally, the flow path substrate and the actuator are joined together (step S5).

[0127] In the joining process, after bonding the parts together with the aforementioned adhesive, the parts are heated to approximately 80°C. It is preferable to avoid exposing the protective film on the actuator to high temperatures as much as possible. Therefore, it is preferable to join the nozzle substrate and the flow path substrate first, and then join the flow path substrate and the actuator last, that is, to perform step S4 followed by step S5. However, in this embodiment, the protective film has sufficient heat resistance, so it is less likely to deteriorate even if exposed to high temperatures for a long time. In other words, the order of steps S4 and S5 may be reversed.

[0128] Figure 8 is a flowchart illustrating the actuator manufacturing process. First, the actuator base material is formed (step S11). Next, the formed base material is protected with a protective film (step S12). Here, "base material" refers to the components of the actuator that come into contact with the ink. Specifically, in the bend mode, the pressure chamber layer 31 and the diaphragm 32 correspond to the base material, and in the shear mode, the drive electrode 14 corresponds to the base material.

[0129] When the base material contains nickel, it is preferable to form the base material by sputtering or plating. This allows for the formation of a uniform layer with consistent thickness.

[0130] Figure 9 is a flowchart illustrating the protection process. The organic layer of the protective film is formed by the CVD method described above. Details of the CVD method are as described above. The inorganic layer of the protective film is not particularly limited, but it is preferably formed by sputtering or atomic layer deposition. Details of the sputtering method and atomic layer deposition are as described above. In the flowchart shown in Figure 9, the protective film is configured to have only a first organic layer, an inorganic layer, and a second organic layer, but the protective film may have other layers, and each of the other layers can be formed using conventionally known methods.

[0131] First, a first organic layer is formed on the substrate by CVD (Step S121). Next, an inorganic layer is formed on the formed first organic layer (Step S122). Finally, a second organic layer is formed on the formed inorganic layer by CVD (Step S123). Note that the organic layer may be stabilized by heating after formation.

[0132] It is preferable to form the first organic layer, the inorganic layer, and the second organic layer continuously without opening to the atmosphere from the start of the first organic layer formation step S121 until the end of the second organic layer formation step S123. By forming them continuously, it is possible to suppress the incorporation of impurities originating from atmospheric components at the interfaces of each layer.

[0133] The layer formation by the CVD method is preferably carried out at room temperature (25°C) ± 10°C, i.e., within the range of 15 to 35°C, and more preferably at room temperature (25°C) ± 5°C, i.e., within the range of 20 to 30°C. The heat treatment after layer formation is preferably carried out at a range of 60 to 150°C, and more preferably at a range of 80 to 120°C. Heating within the above range makes the layer less prone to deformation even in subsequent high-temperature environments.

[0134] In the step of heating the second organic layer, both the first and second organic layers are essentially heated. Therefore, the step of heating the first organic layer may be omitted, but it is preferable to perform the step of heating the first organic layer. By shrinking the first organic layer once to change its crystal structure before forming the inorganic layer and the second organic layer, deformation of the first organic layer during the heating of the second organic layer can be suppressed. As a result, a decrease in adhesion between the substrate and the first organic layer, and between the first organic layer and the inorganic layer, can be suppressed.

[0135] As an alternative manufacturing method, each substrate may be joined with an adhesive, and then a protective film may be formed over the entire surface that comes into contact with the ink. In this embodiment, a uniform and even protective film can be formed even on the surface of the channel where multiple different materials are joined, so this method can also adequately protect the channel.

[0136] [Inkjet Recording Device] Figure 10 is a schematic diagram showing the general configuration of the inkjet recording device 100 of this embodiment. The inkjet recording device 100 includes a transport unit 110 and a recording unit 120 having a plurality of line heads 121, etc.

[0137] The transport unit 110 (moving means) comprises a first transport roller 111, a second transport roller 112, and a transport belt 113. The first transport roller 111 and the second transport roller 112 rotate around a rotation axis extending to the left in Figure 10. The transport belt 113 is a ring-shaped belt whose inner side is supported by the first transport roller 111 and the second transport roller 112. The transport belt 113 moves in a circular motion around the first transport roller 111 and the second transport roller 112 as the first transport roller 111 rotates in response to the operation of a transport motor (not shown). The transport unit 110 transports the recording medium M in the direction of movement of the transport belt 113 (forward direction in Figure 10) by having the transport belt 113 move in a circular motion with the recording medium M placed on the transport surface of the transport belt 113. In other words, the transport unit 110 moves the line head 121 of the recording unit 120 and the recording medium M relative to each other in the forward direction.

[0138] The recording medium M may be, for example, a sheet of paper cut to a certain size. The recording medium M is supplied onto the conveyor belt 113 by a paper feeder (not shown), and ink is ejected from the line head 121 to record an image. After that, the recording medium M is discharged from the conveyor belt 113 to a predetermined paper discharge section. A long medium such as roll paper may be used as the recording medium M. Examples of recording medium M include plain paper, coated paper, cloth, or sheet-like resin.

[0139] The recording unit 120 is equipped with four line heads 121, each corresponding to one of four ink colors: yellow (Y), magenta (M), cyan (C), and black (K). The line heads 121 eject ink at appropriate timings based on image data onto the recording medium M transported by the transport unit 110 to record an image. The four line heads 121 are arranged at predetermined intervals from the upstream side in the transport direction (forward direction) of the recording medium M, for example, in the order of colors Y, M, C, and K. The number of line heads 121 can be changed depending on the number of colors used, and may be three or fewer, or five or more.

[0140] Figure 11 is a schematic diagram of the line head 121 as viewed from the conveyor belt 113 side. The line head 121 has a plurality of inkjet heads 1, each provided with a plurality of nozzles 51 for ejecting ink. In each inkjet head 1, the plurality of nozzles 51 are arranged in the left-right direction to form a nozzle row. Alternatively, as shown in Figure 11, two inkjet heads 1 may be combined to form a single head module 101.

[0141] Furthermore, the detailed configuration of each device constituting the inkjet head can also be modified as appropriate without departing from the spirit of the present invention.

[0142] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, the units "parts" or "%" are used, and unless otherwise specified, they represent "parts by mass" or "mass%". In addition, in the following examples, the operations were carried out at room temperature (25°C) unless otherwise specified.

[0143] For the bend mode actuator of the inkjet head "KM800 series" (manufactured by Konica Minolta, Inc.), the protective film on the surface in contact with the ink was replaced with a protective film with the configuration shown in Table I to obtain actuators (ACTs) for each comparative example or example. The substrate material of the actuator was nickel. Note that PPX and PPX-NH ２ The following compounds were used. n1, n21, n22, and n3 represent the polymerization number.

[0144]

[0145] (Example 1) In Example 1 (ACT1), a 1 μm thick layer of PPX[P-1] was formed as the first layer of the protective film on the surface of the actuator that comes into contact with the ink, using a vapor deposition apparatus (manufactured by SCS). Specifically, a monochloroparaxylylene dimer was used as the film-forming material, and the dimer was sublimated in a sublimation furnace and then decomposed in a pyrolysis furnace. The surface of the actuator that comes into contact with the ink (the surface on which the protective film is to be formed) was exposed to the resulting vapor at a film-forming pressure of 40 mTorr and room temperature (25°C) to form the first layer.

[0146] Next, an inorganic layer was formed on the first layer as the second protective layer. The inorganic layer had a two-layer structure, with Al from the first layer side. ２ O ３ layer, TiO ２ The layers were formed in a specific order. The inorganic layer was formed by atomic layer deposition using the R-200 Advanced atomic layer deposition system (manufactured by PICOSUN).

[0147] Al ２ O ３ The layer was formed on the first layer with a thickness of 0.04 μm (40 nm) by alternating exposure to trimethylaluminum (TMA) and water at a deposition temperature of 100°C. ２ The layer is formed by alternating exposure to tetrakis(dimethylamino)titanium (TDMAT) and water at a deposition temperature of 100°C, and then Al ２ O ３ The first layer was formed with a thickness of 0.01 μm (10 nm). The total thickness of the second layer was 0.05 μm (50 nm).

[0148] Next, as the third protective layer, a 4 μm thick PPX-NH coating was applied to the formed second layer using a vapor deposition apparatus (manufactured by SCS Corporation). ２ Layer [N-1] was formed. Specifically, dimers of dichloroparacyclophane and aminoparacyclophane were used as film-forming materials, and these dimers were sublimated. The resulting vapor was used to form the third layer by exposing the surface of the actuator that comes into contact with the ink (the surface forming the protective film) to the vapor at a film-forming pressure of 40 mTorr and room temperature (25°C).

[0149] Next, ACT1 underwent heat treatment. As part of the heat treatment, the actuator was heated at 100°C for 3 hours. This heat treatment was intended to bond the actuator, the flow path substrate, and the nozzle substrate using a thermosetting adhesive.

[0150] (Examples 2-5 and Comparative Examples 1-2) Actuators (ACT2-7) were manufactured using the same procedure as in Example 1, except that the material and thickness of the first layer (first organic layer), the material and thickness of the third layer (second organic layer), and the heat treatment conditions were changed as shown in Table I.

[0151] Table I below shows the composition of the protective film and the heat treatment conditions for each actuator.

[0152]

[0153] The following durability tests were conducted on the KM800 inkjet head (manufactured by Konica Minolta, Inc.) equipped with the obtained actuator. The KM800 has 800 nozzles and 800 corresponding drive elements. Each drive element has a predetermined electrical capacity, and the normal operation of the drive function can be determined by measuring the electrical capacity of the drive element. The ink used was a reactive dye ink, specifically pure ink (cyan, manufactured by Konica Minolta, Inc.) for the Nassenger inkjet textile printer. Note that this reactive dye ink is an acidic water-based ink, and corrosion is particularly likely to occur if the actuator's substrate is made of metal such as nickel.

[0154] <Driving Conditions> Driving device: Inkjet control system "IJCS-1" (manufactured by Konica Minolta, Inc.) Applied voltage: 17V Frequency: 40kHz Test temperature: Room temperature (25℃)

[0155] <Evaluation Method> The capacitance of each drive element was measured after each number of applied pulses shown in Table II. Drive elements whose capacitance was not within ±20% of the initial value were judged to be abnormal. The inkjet head was evaluated to see if it was functioning normally according to the following criteria. AA and A were considered acceptable, as there were no practical problems. AA: All 800 drive elements showed normal capacitance. A: One or two out of 800 drive elements showed abnormal capacitance. B: Three or more out of 800 drive elements showed abnormal capacitance.

[0156] The evaluation results are shown in Table II below.

[0157]

[0158] From the comparative examples and examples, by using the protective film of this embodiment, that is, PPX-NH ２ It can be seen that the heat resistance of the inkjet head is improved by having this layer. In addition, the actuator has many uneven structures such as corners, edges, and steps, but a protective film of uniform thickness is formed on these uneven structures, and as a result it can be seen that the durability of the inkjet head is improved.

[0159] From Examples 1 and 2, PPX-NH was placed on the side that comes into contact with the ink. ２ It can be seen that the heat resistance is improved by the placement of this layer.

[0160] Examples 1, 3, and 4 show that the protective film of this embodiment has sufficient heat resistance even when subjected to high temperature and prolonged heat treatment. Furthermore, Example 5 shows that the protective film of this embodiment contains PPX-NH in both the first layer (first organic layer) and the third layer (second organic layer). ２ It can be seen that the presence of this layer further improves heat resistance.

[0161] By using the present invention, the thickness of the protective film can be made uniform, and its heat resistance can be improved. As a result, the lifespan of the inkjet head having the protective film and the inkjet recording device (printer) equipped with the inkjet head can be extended.

[0162] 1 Inkjet head 2 Adhesive layer 4 Protective film 6 Housing 7 Cover member 11 Drive channel 12 Dummy channel 13 Drive wall 14 Drive electrode 15 Connecting electrode 21 Supply channel 22 Pressure chamber 23 Supply side communication channel 24 Nozzle side communication channel 30 Actuator 31 Pressure chamber layer 32 Diaphragm 33 Insulating layer 34 Piezoelectric layer 35 Electrode layer 40 Channel substrate 41 First organic layer 42 Inorganic layer 43 Second organic layer 44 Fourth layer 45 Fifth layer 50 Nozzle substrate 51 Nozzle 60 Ink 61 Droplet 68 Mounting hole 70 Laminate 71 Substrate 100 Inkjet recording device 101 Head module 110 Transport section 111 First transport roller 112 Second transport roller 113 Transport belt 120 Recording unit 121 Line head

Claims

1. A protective film comprising, in order, a first organic layer, an inorganic layer, and a second organic layer, wherein the first organic layer and the second organic layer contain polyparaxylylene or a derivative thereof having a structure represented by the following general formula (1), or a derivative of polyparaxylylene having a structure represented by the following general formula (2), and at least one of the first organic layer and the second organic layer contains a derivative of polyparaxylylene having a structure represented by the following general formula (2). In general formula (1), each of the a X1 atoms independently represents an alkyl group having 1 to 5 carbon atoms, or a halogen atom. a represents an integer from 0 to 4. n1 represents the polymerization number. In general formula (2), each of the b X2 atoms independently represents an alkyl group having 1 to 5 carbon atoms, or a halogen atom. b is an integer from 0 to 4. n2 represents the number of polymerization units. Each of the c X3 atoms independently represents an alkyl group having 1 to 5 carbon atoms. c is an integer from 0 to 3. d is an integer from 1 to 4. n3 represents the number of polymerization units.

2. The protective film according to claim 1, wherein the second organic layer contains a derivative of polyparaxylylene having the structure represented by the general formula (2).

3. The protective film according to claim 1, wherein both the first organic layer and the second organic layer contain a derivative of polyparaxylylene having the structure represented by the general formula (2).

4. The protective film according to claim 1, wherein the thickness of the first organic layer is in the range of 0.1 to 10 μm.

5. The protective film according to claim 1, wherein the thickness of the second organic layer is in the range of 0.1 to 10 μm.

6. The protective film according to claim 1, wherein the thickness of the inorganic layer is in the range of 10 to 500 nm.

7. The protective film according to claim 1, wherein the inorganic layer comprises a film containing an oxide of aluminum, silicon, titanium, hafnium, or tantalum.

8. A method for manufacturing a protective film according to any one of claims 1 to 7, comprising: a first organic layer formation step of forming the first organic layer; an inorganic layer formation step of forming the inorganic layer on the formed first organic layer; and a second organic layer formation step of forming the second organic layer on the formed inorganic layer, wherein in the inorganic layer formation step, the inorganic layer is formed using chemical vapor deposition, sputtering, or atomic layer deposition.

9. An inkjet head having a channel through which ink flows, the surface of the channel having a protective film according to any one of claims 1 to 7, wherein the first organic layer is located on the surface side of the channel and the second organic layer is located on the side that comes into contact with the ink.

10. The inkjet head according to claim 9, wherein the surface of the flow channel has an uneven structure.

11. The inkjet head according to claim 9, wherein the surface of the flow channel exposes an adhesive and substrates of multiple different materials.

12. The inkjet head according to claim 9, comprising an actuator, a flow channel substrate, and a nozzle substrate, wherein the actuator, the flow channel substrate, and the nozzle substrate are joined together with an adhesive.

13. A method for manufacturing an inkjet head according to claim 12, wherein the protective film is exposed to an environment of 80°C or higher.

14. An inkjet recording apparatus comprising the inkjet head described in claim 12.

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