Liquid ejection structure, liquid ejection head and liquid ejection device

Abstract

The present invention provides a liquid ejection structure and its application, wherein the liquid ejection structure comprises a nozzle substrate formed with a nozzle for ejecting liquid, and a flow path substrate formed with a liquid flow path connected to the nozzle, wherein the nozzle substrate has a first layer, a second layer and a liquid-repellent layer in sequence on the ejection surface, and has a first layer and a second layer in sequence on the inner wall of the liquid flow path, wherein the first layer is a layer comprising at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide and hafnium oxide, and the second layer is a layer comprising at least one selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON.

Description

Technical Field

[0001] The present invention relates to a liquid ejection structure, a liquid ejection head and a liquid ejection device. Background Art

[0002] Generally, a liquid ejection head represented by an inkjet head mounted on an inkjet recording device has a nozzle for ejecting liquid. Liquid is supplied from a liquid supply chamber to a liquid flow path, and ejected from a nozzle hole formed in the nozzle connected to the liquid flow path.

[0003] For example, Japanese Patent Publication No. 2009-184176 describes a liquid droplet ejection head, which includes a nozzle substrate, the nozzle substrate includes a plurality of nozzle holes, the nozzle hole includes at least a nozzle portion for ejecting liquid droplets and an introduction portion having a larger cross-sectional area than the nozzle portion and arranged coaxially with the nozzle portion, and the nozzle substrate has a plurality of layers of ejection liquid resistant protective films formed on at least the inner wall of the nozzle hole. Also, Japanese Patent Publication No. 2014-124876 describes a liquid droplet ejection head, which includes a plurality of nozzle openings on a silicon substrate, a hafnium oxide film or a zirconium oxide film formed by atomic layer deposition on both surfaces of the silicon substrate and the inner surface of the nozzle opening, and a nozzle plate having a plasma polymerized film of a silicone material provided on the hafnium oxide film or the zirconium oxide film on the ejection surface. Furthermore, Japanese Patent Gazette No. 2009-220471 describes a liquid ejection head having a nozzle plate formed with a nozzle hole for ejecting liquid droplets, and pressurizing liquid in a liquid chamber connected to the nozzle hole so that the liquid is ejected from the nozzle hole. The liquid ejection head forms a titanium or titanium oxide film on the ejection side of the nozzle plate surface, forms a silicon oxide film on the titanium or titanium oxide film, forms a hydrophobic layer on the silicon oxide film, forms a silicon oxide film on the liquid chamber side of the nozzle plate surface and on the inner wall of the nozzle hole, the titanium or titanium oxide film is covered by the silicon oxide film, and the interface between the silicon oxide film and the titanium or titanium oxide film is not exposed on the contact liquid surface. Summary of the invention

[0004] Technical issues to be solved by the invention

[0005] Since the liquid dries after being ejected, the components contained in the liquid adhere to the ejection surface of the liquid ejection head as foreign matter. If foreign matter adheres to the nozzle surface, it is easy to cause poor ejection. Therefore, in the liquid ejection device, the ejection surface of the liquid ejection head is wiped regularly to remove foreign matter. However, the durability of the ejection surface of the liquid ejection head is sometimes reduced by wiping, and durability to wiping (hereinafter also referred to as "wipe resistance") is required.

[0006] Furthermore, when an alkaline liquid is used, the durability of the ejection surface and the liquid flow path of the liquid ejection head may be reduced, and durability against alkali (hereinafter also referred to as "alkali resistance") is required.

[0007] In contrast, in Japanese Patent Application Laid-Open No. 2009-184176, a silicon oxide film, a metal oxide film, and a hydrophobic film are sequentially provided on the ejection surface. Since the hydrophobic film and the metal oxide film have insufficient adhesion, it is considered that the ejection surface has poor abrasion resistance.

[0008] Furthermore, in Japanese Patent Application Publication No. 2014-124876, a hafnium oxide film or a zirconium oxide film, a plasma polymerized film of a silicone material, and a liquid-repellent film are sequentially provided on the ejection surface. The plasma polymerized film has few bonding points and many pinholes. Therefore, the adhesion between the liquid-repellent film and the plasma polymerized film is insufficient, and it is believed that the abrasion resistance of the ejection surface is poor.

[0009] Furthermore, in Japanese Patent Application Laid-Open No. 2009-220471, a titanium or titanium oxide film and a silicon oxide film are sequentially provided on a portion of the inner wall of the nozzle hole. However, only the silicon oxide film is provided on the liquid chamber side of the nozzle plate surface, and it is considered that the alkali resistance is poor.

[0010] The present invention is completed in view of this situation, and the problem to be solved by one embodiment of the present invention is to provide a liquid ejection structure, a liquid ejection head and a liquid ejection device with excellent wipe resistance of the ejection surface and excellent alkali resistance of the ejection surface and the liquid flow path.

[0011] Means for solving technical problems

[0012] The present invention includes the following aspects.

[0013] <1> A liquid ejection structure, comprising a nozzle substrate formed with a nozzle for ejecting liquid, and a flow path substrate formed with a liquid flow path connected to the nozzle, wherein the nozzle substrate has a first layer, a second layer and a liquid-repellent layer in sequence on the ejection surface, and has a first layer and a second layer in sequence on the inner wall of the liquid flow path, wherein the first layer is a layer comprising at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide and hafnium oxide, and the second layer is a layer comprising at least one selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON.

[0014] <2> according to <1> In the liquid ejection structure, the first layer is a layer of tantalum oxide, zirconium oxide, or hafnium oxide.

[0015] <3> according to <1> or <2> The liquid ejection structure, wherein the second layer is a SiO2 layer.

[0016] <4> according to <1> to <3> The liquid ejection structure described above, wherein the first layer has a thickness of 10 nm to 50 nm.

[0017] <5> according to <1> to <4> In any one of the above liquid ejection structures, the second layer has a thickness of 0.3 nm to 3 nm or 10 nm to 100 nm.

[0018] <6> according to <1> to <5> In any one of the above liquid ejection structures, the thickness of the second layer is 0.3 nm to 2 nm.

[0019] <7> according to <1> to <6> In any one of the above liquid ejection structures, a ratio of a thickness of the second layer to a thickness of the first layer is 0.006 to 0.3.

[0020] <8> according to <1> to <7> The liquid ejection structure described above, wherein the liquid-repellent layer contains a silicon compound having a perfluoropolyether structure.

[0021] <9> according to <1> to <8> The liquid ejection structure described above, wherein the thickness of the liquid-repellent layer is 3 nm to 8 nm.

[0022] <10> according to <1> to <9> In any one of the liquid ejection structures, the liquid flow path includes a circulation flow path for circulating the liquid.

[0023] <11> A liquid ejection head having <1> to <10> The liquid ejection structure described above.

[0024] <12> A liquid ejection device comprising <11> The liquid ejection head.

[0025] <13> according to <12> The liquid ejection device has the function of making the liquid <11> A liquid circulation mechanism for circulating between the liquid ejection head and the liquid tank.

[0026] Effects of the Invention

[0027] According to the present invention, there are provided a liquid ejection structure, a liquid ejection head, and a liquid ejection device having an ejection surface having excellent wiping resistance and an ejection surface and an internal flow path having excellent alkali resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic cross-sectional view showing one embodiment of the liquid ejection structure of the present invention.

[0029] Figure 2 yes Figure 1 Enlarged view of the dashed box A in FIG.

[0030] Figure 3 yes Figure 1 Enlarged view of the dashed box B in FIG.

[0031] Figure 4It is a schematic cross-sectional view showing a modified example of the liquid ejection structure of the present invention.

[0032] Figure 5 This is a schematic cross-sectional view showing one embodiment of the liquid ejecting head of the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, the liquid ejection structure, the liquid ejection head, and the liquid ejection device of the present invention will be described in detail.

[0034] In the present invention, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0035] In the present invention, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition refers to the total amount of the plurality of substances present in the composition unless otherwise specified.

[0036] In the numerical ranges described stepwise in the present invention, the upper limit value or the lower limit value described in a certain numerical range may be replaced by the upper limit value or the lower limit value of the numerical range described stepwise, or may be replaced by the value shown in the Examples.

[0037] In the present invention, the term "process" refers not only to an independent process but also to a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0038] In the present invention, a combination of preferred embodiments is a more preferred embodiment.

[0039] The elements in the drawings showing the present invention are not necessarily in exact proportions, but are mainly intended to clearly illustrate the principles of the present invention, and some parts may be emphasized.

[0040] In the present invention, the "lyophobic layer" refers to a layer having a contact angle with water of 60° or more. The contact angle with water is a value measured at 25°C using a contact angle meter such as a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., LTD.).

[0041] In the present invention, "internal flow path" refers to a path formed inside the liquid ejection structure and through which liquid passes. That is, "internal flow path" is a concept that includes nozzles formed on the nozzle substrate and liquid flow paths formed on the flow path substrate.

[0042] In the present invention, the "ejection surface" refers to the surface of the nozzle substrate on the side where the liquid is ejected in the liquid ejection structure.

[0043] In the present invention, the "inner wall of the liquid flow path" refers to the surface of the flow path substrate on which the liquid flow path is formed. Also, the "inner wall of the nozzle" refers to the surface of the nozzle substrate on which the nozzle is formed.

[0044] [Liquid ejection structure]

[0045] The liquid ejection structure of the present invention comprises a nozzle substrate on which a nozzle for ejecting liquid is formed, and a flow path substrate on which a liquid flow path connected to the nozzle is formed. The ejection surface of the nozzle substrate has a first layer, a second layer, and a liquid-repellent layer in sequence, and the inner wall of the liquid flow path has a first layer and a second layer in sequence. The first layer is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide. The second layer is a layer containing at least one selected from the group consisting of SiO2, SiC, SiN, SiCN, and SiON.

[0046] The first layer, the second layer, and the liquid-repellent layer are sequentially provided on the ejection surface of the nozzle substrate, which means that the liquid-repellent layer is located on the outermost surface of the nozzle substrate. That is, the liquid-repellent layer is the outermost layer of the plurality of layers provided on the nozzle substrate. Since the liquid ejection structure of the present invention has the liquid-repellent layer on the outermost surface of the nozzle substrate, the antifouling property of the ejection surface is excellent.

[0047] Furthermore, the liquid ejection structure of the present invention has a second layer, which is a layer including at least one selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON, below the liquid-repellent layer as the outermost layer in the nozzle substrate. The at least one layer selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON has high adhesion to the liquid-repellent layer, and the ejection surface has excellent abrasion resistance.

[0048] Furthermore, the liquid ejection structure of the present invention has a first layer below the second layer, which is a layer including at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, in the nozzle substrate, the nozzle, and the liquid flow path. At least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide has excellent alkali resistance. Therefore, when alkaline liquid penetrates into the second layer due to long-term use, the alkali resistance of the ejection surface and the internal flow path can be maintained due to the presence of the first layer.

[0049] Hereinafter, one embodiment of the liquid ejection structure of the present invention will be described with reference to the drawings.

[0050] Figure 1 It is a cross-sectional view showing one embodiment of the liquid ejection structure of the present invention.

[0051] like Figure 1As shown, the liquid ejection structure 100 includes a nozzle substrate 10 formed with nozzles 30 for ejecting liquid, and a flow path substrate 20 formed with a liquid flow path 40 communicating with the nozzles 30. The nozzle substrate 10 and the flow path substrate 20 are preferably bonded by bonding or the like.

[0052] The type of liquid supplied to the liquid ejection structure 100 is not particularly limited. The liquid ejection structure 100 uses a liquid ejection head described later and assembles the liquid ejection head to a liquid ejection device described later, thereby enabling fine liquid droplets to be ejected from the nozzle 30. Ink is preferably used as the liquid, and an image can be recorded by ejecting fine ink droplets onto a substrate.

[0053] The ink used to record the image is, for example, a liquid containing a colorant, a solvent, and a surfactant. In addition, a pre-treatment liquid may be ejected onto the substrate before the ink is ejected onto the substrate, or a post-treatment liquid may be ejected after the ink is ejected. Thus, as the liquid supplied to the liquid ejection structure 100, in addition to the ink, a pre-treatment liquid and a post-treatment liquid may also be cited. The pre-treatment liquid and the post-treatment liquid are usually colorless liquids that do not contain a colorant.

[0054] Furthermore, the liquid supplied to the liquid ejection structure 100 may be an acidic liquid or an alkaline liquid. The liquid ejection structure 100 is suitable for alkaline liquids because the ejection surface and the inside of the flow path have excellent alkali resistance. In particular, the liquid ejection structure 100 is suitable for liquids with a pH of 8 to 11. The pH is a value measured at 25°C using a pH meter, for example, a value measured using a product name "Handy type pH meter" manufactured by SATOKEIRYOKI MFG.CO., LTD.

[0055] <Nozzle substrate>

[0056] The nozzle substrate 10 is a substrate made of silicon, for example, and may be a single crystal silicon substrate or a polycrystalline silicon substrate. The nozzle substrate 10 has a nozzle 30 formed thereon for ejecting liquid.

[0057] The nozzle 30 is a hole that penetrates the nozzle substrate 10, and is formed, for example, by dry etching. A plurality of nozzles 30 are preferably formed on the nozzle substrate 10. The shape of the nozzle 30 is not particularly limited, but from the perspective of controlling the direction in which the liquid is ejected, it is preferably a cone whose diameter decreases as the direction in which the liquid is ejected is considered. The aperture of the side of the nozzle 30 from which the liquid is ejected, that is, the aperture of the nozzle opening 31, can be appropriately adjusted. When the liquid ejection structure 100 is used in an inkjet head, the aperture of the nozzle opening 31 is, for example, 10 μm to 30 μm.

[0058] The thickness of the nozzle substrate 10 corresponds to the length of the nozzle 30 , and is preferably 10 μm to 100 μm, and more preferably 20 μm to 60 μm.

[0059] Figure 2 yes Figure 1 Enlarged view of the dashed box A in FIG.

[0060] like Figure 2 As shown, a first layer 51 , a second layer 52 , and a liquid-repellent layer 53 are sequentially provided on the ejection surface 101 of the nozzle substrate 10 .

[0061] The first layer 51 is a layer including at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and is preferably a layer of tantalum oxide, zirconium oxide, or hafnium oxide.

[0062] At least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide (preferably tantalum oxide, zirconium oxide, or hafnium oxide) has excellent alkali resistance. Therefore, when alkaline liquid penetrates into the liquid-repellent layer and the second layer provided on the ejection surface of the nozzle substrate due to long-term use, the alkali resistance of the ejection surface can be maintained due to the presence of the first layer.

[0063] The thickness of the first layer 51 is preferably 3 nm to 70 nm, more preferably 10 nm to 50 nm, and further preferably 20 nm to 50 nm. If the thickness of the first layer 51 is 3 nm or more, alkaline liquid is not easy to penetrate, and the scratch resistance and alkali resistance of the ejection surface are more excellent. On the other hand, if the thickness of the first layer 51 is 70 nm or less, defects are not easy to occur in the layer, and the scratch resistance and alkali resistance of the ejection surface are more excellent. In addition, from the perspective of productivity, the thickness of the first layer 51 is preferably 50 nm or less.

[0064] The second layer 52 is a layer including at least one selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON, preferably a SiO2 layer. The layer including at least one selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON (preferably a SiO2 layer) has high adhesion to the liquid-repellent layer 53. Therefore, the alkaline liquid does not easily penetrate into the liquid-repellent layer 53 and the second layer 52, and the abrasion resistance and alkali resistance of the ejection surface are excellent.

[0065] The thickness of the second layer 52 is preferably 0.3 nm to 120 nm, more preferably 0.3 nm to 3 nm or 10 nm to 100 nm, further preferably 0.3 nm to 3 nm, and particularly preferably 0.5 nm to 2 nm. In particular, when the thickness of the second layer 52 is 0.3 nm to 3 nm or 10 nm to 100 nm, the adhesion between the second layer 52 and the liquid-repellent layer 53 is improved, and the abrasion resistance and alkali resistance of the ejection surface are more excellent.

[0066] The ratio of the thickness of the second layer 52 to the thickness of the first layer 51 is preferably 0.006 or more and 6 or less, more preferably 0.006 or more and 0.3 or less, further preferably 0.01 or more and 0.15 or less, and particularly preferably 0.01 or more and 0.1 or less. In particular, if the ratio of the thickness of the second layer 52 to the thickness of the first layer 51 is 0.006 or more and 0.3 or less, the alkaline liquid is not easy to penetrate into the first layer 51, and the abrasion resistance and alkali resistance of the ejection surface are more excellent. Furthermore, if the ratio of the thickness of the second layer 52 to the thickness of the first layer 51 is 0.01 or more and 0.15 or less, the adhesion between the first layer 51 and the second layer 52 is high, and the abrasion resistance and alkali resistance of the ejection surface are more excellent.

[0067] The liquid-repellent layer 53 is a layer having a contact angle with water of 60° or more. The contact angle with water of the liquid-repellent layer 53 is preferably 70° or more, more preferably 80° or more. Since the liquid-repellent layer 53 is provided on the outermost surface of the nozzle substrate 10, the ejection surface has excellent wiping resistance.

[0068] From the perspective of showing liquid repellency, the liquid repellent layer 53 preferably contains a fluorine-containing compound, and more preferably contains a compound having a perfluoropolyether structure. The compound having a perfluoropolyether structure has a highly flexible and dense molecular structure. Therefore, it is possible to inhibit alkaline liquid from penetrating into the interior of the liquid repellent layer 53, and the alkali resistance is more excellent. In addition, since the perfluoropolyether structure has a high fluorine content, even if it is wiped, fluorine atoms are likely to remain on the surface of the liquid repellent layer 53, and the contact angle is not easy to decrease. That is, the wipe resistance of the ejection surface is excellent.

[0069] Furthermore, from the viewpoint of adhesion with the second layer 52, which is a layer including at least one selected from the group consisting of SiO2, SiC, SiN, SiCN, and SiON, the liquid-repellent layer 53 is preferably formed using a silicon coupling agent, and more preferably formed using a silicon coupling agent having a perfluoropolyether structure. That is, it is further preferred that the liquid-repellent layer 53 is a silicon compound having a perfluoropolyether structure.

[0070] Examples of the perfluoropolyether structure include structures represented by the following formulae 1 to 3. Among them, the perfluoropolyether structure is preferably a structure represented by the following formula 1.

[0071] CF3O-(CF2O) n -(CF2CF2O) m -*……(1)

[0072] In Formula 1, m represents an integer of 0 to 200, n represents an integer of 0 to 300, and m+n is greater than or equal to 1. * represents a bonding position to other structures in the compound.

[0073] In Formula 1, m is preferably an integer of 0 to 50, and more preferably an integer of 1 to 50. Also, n is preferably an integer of 0 to 50, and more preferably an integer of 1 to 50.

[0074] CF3-(CF2OCF2O) n -*……(2)

[0075] In Formula 2, n represents an integer of 1 to 100. * represents a bonding position with other structures in the compound.

[0076] CF3-(CF2O) n -*……(3)

[0077] In Formula 3, n represents an integer of 1 to 300. * represents a bonding position with other structures in the compound.

[0078] The thickness of the liquid-repellent layer 53 is preferably 3 nm to 12 nm, and more preferably 3 nm to 8 nm. If the thickness of the liquid-repellent layer 53 is 3 nm or more, the wiping resistance is improved. On the other hand, if the thickness of the liquid-repellent layer 53 is 12 nm or less, it is difficult for aggregates derived from the components constituting the liquid-repellent layer 53 to adhere to the surface of the liquid-repellent layer 53, and it is possible to suppress the aggregates from being inserted into the nozzle 30. As a result, the ejection performance of the liquid is suppressed from being reduced.

[0079] Figure 3 yes Figure 1 Enlarged view of the dashed box B in FIG.

[0080] like Figure 3 As shown, the liquid ejection structure 100 has a first layer 51 and a second layer 52 in this order on the inner wall 102 of the nozzle 30. The first layer 51 and the second layer 52 provided on the inner wall 102 of the nozzle 30 are the same as the first layer 51 and the second layer 52 provided on the ejection surface 101 of the nozzle substrate 10.

[0081] Since the liquid ejection structure 100 includes the first layer 51 and the second layer 52 in this order on the inner wall 102 of the nozzle 30 , the inner wall 102 of the nozzle 30 has excellent alkali resistance.

[0082] <Flow path substrate>

[0083] The flow path substrate 20 is, for example, a substrate made of silicon, which may be a single crystal silicon substrate or a polycrystalline silicon substrate. Figure 1 As shown, the flow path substrate 20 is composed of a wall member 21 and a cover member 22, and preferably the wall member 21 and the cover member 22 are bonded together by bonding or the like. A liquid flow path 40 connected to the nozzle 30 is formed in the flow path substrate 20. The liquid flow path 40 includes a nozzle communication channel 41, a pressure chamber 42, and a liquid supply channel 43.

[0084] The nozzle communication passage 41 is a flow path connecting the pressure chamber 42 and the nozzle 30. The nozzle communication passage 41 is preferably linear in cross-sectional view.

[0085] The pressure chamber 42 is a flow path whose volume is changed by applying a driving voltage when the liquid ejection structure 100 is used in a liquid ejection head described later. The pressure chamber 42 has a substantially square planar shape when the liquid ejection structure 100 is viewed from above, and a liquid outlet to the nozzle communication channel 41 is provided at one of the two corners on the diagonal line, and a liquid inlet, i.e., a liquid supply channel 43, is provided at the other. The planar shape of the pressure chamber 42 is not limited to a substantially square shape, and may also be a rectangle, a trapezoid, or the like.

[0086] The liquid supply channel 43 is a flow path connected to a liquid tank (not shown) when the liquid discharge structure 100 is assembled into a liquid discharge device described later. Liquid is supplied from the liquid tank to the pressure chamber 42 via the liquid supply channel 43. The arrows in the figure indicate the direction of liquid flow.

[0087] and Figure 3 Similarly, on the inner wall 102 of the nozzle 30 shown, the liquid ejection structure 100 has the first layer 51 and the second layer 52 in this order on the inner wall 201 of the liquid flow path 40. The first layer 51 and the second layer 52 provided on the inner wall 201 of the liquid flow path 40 are the same as the first layer 51 and the second layer 52 provided on the ejection surface 101 of the nozzle substrate 10. Specifically, the inner wall 201 of the liquid flow path 40 includes the surface of the wall member 21 on the side where the liquid flow path 40 is formed, the surface of the cover member 22 on the side where the liquid flow path 40 is formed, and the surface of the nozzle substrate 10 on the side where the liquid flow path 40 is formed.

[0088] Since the liquid ejection structure 100 includes the first layer 51 and the second layer 52 in this order on the inner wall 201 of the liquid flow path 40 , the inner wall 201 of the liquid flow path 40 has excellent alkali resistance.

[0089] In addition, the structure of the flow path substrate 20 is Figure 1 In addition to the structure shown, for example, Figure 4 The structure shown.

[0090] Figure 4 It is a schematic cross-sectional view showing a modified example of the liquid ejection structure of the present invention.

[0091] like Figure 4 As shown, the liquid ejection structure 100A includes a nozzle substrate 10 and a flow path substrate 20A having a liquid flow path 60 communicating with the nozzle 30. The nozzle substrate 10 has the above-described structure. The liquid flow path 60 includes a nozzle communication channel 61, a pressure chamber 62, a liquid supply channel 63, and a circulation channel 64.

[0092] The nozzle communication passage 61 is similar to the nozzle communication passage 41 described above, and is a flow path connecting the pressure chamber 62 and the nozzle 30 .

[0093] The pressure chamber 62 , like the pressure chamber 42 , is a flow path whose volume is changed by application of a driving voltage when the liquid ejection structure 100A is used in a liquid ejection head described later.

[0094] The liquid supply channel 63 is similar to the liquid supply channel 43 and is a flow path connected to a liquid tank (not shown) when the liquid discharge structure 100A is assembled into a liquid discharge device described later. Liquid is supplied from the liquid tank to the pressure chamber 62 through the liquid supply channel 63 .

[0095] The circulation flow path 64 is a flow path connected to a liquid tank (not shown) when the liquid ejection structure 100A is assembled to a liquid ejection device described later. The liquid is delivered to the nozzle 30 through the liquid supply channel 63, the pressure chamber 62, and the nozzle communication channel 61, but the liquid that is not ejected from the nozzle opening 31 of the nozzle 30 is recovered to the liquid tank through the circulation flow path 64.

[0096] The liquid ejection structure 100A has a first layer 51 and a second layer 52 in this order on the inner wall 201A of the liquid flow path 60, similarly to the inner wall 201 of the liquid flow path 40. The first layer 51 and the second layer 52 provided on the inner wall 201A of the liquid flow path 60 are the same as the first layer 51 and the second layer 52 provided on the inner wall 201 of the liquid flow path 40.

[0097] like Figure 1 and Figure 4 As shown, the liquid ejection structure of the present invention is preferably provided with a first layer 51 and a second layer 52 on the inner wall 102 of the nozzle 30. That is, the liquid ejection structure of the present invention comprises a nozzle substrate formed with a nozzle for ejecting liquid, and a flow path substrate formed with a liquid flow path connected to the nozzle, and the ejection surface of the nozzle substrate has a first layer, a second layer and a liquid-repellent layer in sequence, and the inner wall of the nozzle and the inner wall of the liquid flow path have a first layer and a second layer in sequence, the first layer is preferably a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide and hafnium oxide, and the second layer is preferably a layer containing at least one selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON.

[0098] In addition, in both the liquid ejection structure 100 and the liquid ejection structure 100A, the first layer 51 and the second layer 52 are provided on the inner wall 102 of the nozzle 30. However, the first layer 51 and the second layer 52 may not be provided on the inner wall 102 of the nozzle 30. Generally, the area of ​​the inner wall 102 of the nozzle 30 is very small relative to the area of ​​the inner wall 201 of the liquid flow path 40 (the inner wall 201A of the liquid flow path 60). Therefore, even if the first layer 51 and the second layer 52 are not provided on the inner wall 102 of the nozzle 30, the alkali resistance of the internal flow path is excellent.

[0099] <Layer Formation Method>

[0100] Next, a method for forming the first layer 51, the second layer 52 and the liquid-repellent layer 53 on the nozzle substrate 10, the nozzle 30 and the flow path substrate 20 will be described. The first layer 51, the second layer 52 and the liquid-repellent layer 53 are preferably formed after the nozzle substrate 10 and the flow path substrate 20 are bonded to obtain a bonded body.

[0101] First, before forming the first layer 51 on the surface of the joint body of the nozzle substrate 10 and the flow path substrate 20, it is preferred to perform surface treatment on the surface of the joint body in advance. As surface treatment, for example, UV ozone treatment and oxygen plasma treatment can be cited. Among them, from the viewpoint of improving the adhesion between the joint body and the first layer, the surface treatment is preferably oxygen plasma treatment. The irradiation conditions of oxygen plasma can be appropriately adjusted, for example, under the conditions of an output power of 100W to 200W, a flow rate of 50mL / min to 200mL / min, and an irradiation time of 1 minute to 10 minutes.

[0102] Next, the first layer 51 is formed on the surface of the bonded body subjected to the surface treatment. Specifically, the first layer 51 is formed on the ejection surface 101 of the nozzle substrate 10 , the inner wall 102 of the nozzle 30 , and the inner wall 201 of the liquid flow path 40 .

[0103] The first layer 51 is preferably formed by atomic layer deposition (ALD). As the ALD method, a generally known method can be adopted. When the ALD method is used, a dense layer is formed, so the effect of suppressing the penetration of the alkaline liquid is high.

[0104] The first layer 51 can be formed, for example, by repeating the following four steps: placing the surface-treated bonded body in an ALD (Atomic Layer Deposition) chamber, introducing a precursor gas after introducing H2O gas; exhausting the remaining gas; introducing H2O gas; and exhausting the remaining gas.

[0105] First, hydroxyl groups are formed on the surface of the bonded body by introducing H2O gas. Next, hydroxyl groups formed on the surface of the bonded body react with the precursor by introducing the precursor gas. Furthermore, the precursor that reacts with the hydroxyl groups reacts with H2O by introducing the H2O gas.

[0106] Examples of precursors used when forming a tantalum oxide layer as the first layer 51 include tert-butyliminotris(diethylamino)tantalum (TBTDET), tert-butyliminotris(dimethylamino)tantalum (TBTDMT), tert-butyliminotris(ethylmethylamino)tantalum (TBTEMT), ethyliminotris(diethylamino)tantalum (EITDET), ethyliminotris(dimethylamino)tantalum (EITDMT), ethyliminotris(ethylmethylamino)tantalum (EITEMT), tert-amyliminotris(dimethylamino)tantalum (TAIMAT), tert-amyliminotris(diethylamino)tantalum, erythrityl(dimethylamino)tantalum and tert-amyliminotris(ethylmethylamino)tantalum.

[0107] Examples of the precursor used when forming the zirconium oxide layer as the first layer 51 include tetrakis(N-ethylmethylamino)zirconium (TEMAZ) and tris(dimethylamino)cyclopentadienylzirconium (ZAC).

[0108] Examples of the precursor used when forming the titanium oxide layer as the first layer 51 include tetrakis(dimethylamino)titanium (TDMAT), tetrakis(diethylamino)titanium (TDEAT), and tetrakis(ethylmethylamino)titanium (TEMAT).

[0109] Examples of the precursor used when forming the hafnium oxide layer as the first layer 51 include tetrakis(dimethylamino)hafnium (TDMAHf), tetrakis(diethylamino)hafnium (TDEAHf), and tetrakis(ethylmethylamino)hafnium (TEMAHf).

[0110] Furthermore, when forming the first layer 51, ozone gas may be used instead of H2O gas.

[0111] Next, the second layer 52 is formed on the first layer 51 .

[0112] The formation method of the second layer 52 is not particularly limited, and for example, a chemical vapor deposition (CVD) method can be cited. As a CVD method, a generally known method can be used. The formation method of the second layer 52 is more preferably formed by an atomic layer deposition (ALD) method. As an ALD method, a generally known method can be used. If the ALD method is used, a dense layer is formed, so the effect of suppressing the penetration of alkaline liquid is high.

[0113] Next, the liquid-repellent layer 53 is formed on the second layer 52 .

[0114] The method for forming the liquid-repellent layer 53 is not particularly limited, but preferably a method of forming a film by a vapor deposition method using a silane coupling agent after hydrophilizing the surface of the second layer 52. The silane coupling agent is bonded to the hydrophilic group formed on the surface of the second layer after hydrolysis, so that the liquid-repellent layer 53 has high adhesion to the second layer 52, and the penetration of alkaline liquid is suppressed.

[0115] As the hydrophilic treatment, for example, UV ozone treatment and oxygen plasma treatment can be cited. Among them, the hydrophilic treatment is preferably oxygen plasma treatment. The irradiation conditions can be appropriately adjusted, for example, under the conditions of an output power of 100W to 200W, a flow rate of 50mL / min to 200mL / min, and an irradiation time of 1 minute to 10 minutes.

[0116] The film formation method by the vapor deposition method can be performed by, for example, placing a bonded body in which the first layer 51 and the second layer 52 are stacked in a vacuum chamber and placing a silane coupling agent in a vapor deposition boat. The vapor deposition temperature is preferably 100°C to 300°C.

[0117] The silane coupling agent is preferably a fluorine-containing silane coupling agent, more preferably a silane coupling agent having a perfluoropolyether structure, and further preferably an alkoxysilane having a perfluoropolyether structure. Examples of the perfluoropolyether structure include structures represented by Formulae 1 to 3. Preferred embodiments are as described above.

[0118] The silane coupling agent may be a commercially available product, and the following commercially available products may be cited as preferred silane coupling agents. As a silane coupling agent having a structure represented by Formula 1 (in Formula 1, m represents an integer of 1 to 50, and n represents an integer of 1 to 50), KY1901, KY1903, and KY1903-1 manufactured by Shin-Etsu Chemical Co., Ltd. may be cited. Also, as a silane coupling agent having a structure represented by Formula 2 (in Formula 2, n represents an integer of 1 to 100), X-71-195 manufactured by Shin-Etsu Chemical Co., Ltd. may be cited. Also, as a silane coupling agent having a structure represented by Formula 3 (in Formula 3, n represents an integer of 1 to 300), OPTOOL DSX manufactured by DAIKIN INDUSTRIES, LTD. may be cited.

[0119] Furthermore, in order to further improve the adhesion between the second layer 52 and the liquid-repellent layer 53, the bonded body having the first layer 51, the second layer 52, and the liquid-repellent layer 53 laminated thereon is preferably kept under a high temperature and high humidity environment after film formation. For example, the bonded body having the first layer 51, the second layer 52, and the liquid-repellent layer 53 laminated thereon is kept at a temperature of 50 to 90° C. and a humidity of 50% to 90% for 6 to 24 hours.

[0120] Next, the liquid-repellent layer 53 provided on the inner wall 102 of the nozzle 30 and the inner wall 201 of the liquid flow path 40 is removed.

[0121] For example, by sticking tape on the surface of the liquid-repellent layer 53 arranged on the ejection surface of the nozzle substrate 10, and performing oxygen plasma treatment on the nozzle 30 and the liquid flow path 40, the liquid-repellent layer 53 arranged on the inner wall 102 of the nozzle 30 and the inner wall 201 of the liquid flow path 40 can be removed.

[0122] [Liquid ejection head]

[0123] The liquid ejection head of the present invention includes a liquid ejection structure. Figure 5 The liquid ejection head of the present invention will be described.

[0124] Figure 5 It is a cross-sectional view showing one embodiment of the liquid ejecting head of the present invention.

[0125] like Figure 5 As shown, the liquid ejection head 500 includes a liquid ejection structure 100A and a piezoelectric element 70 .

[0126] The structure of the liquid ejection structure 100A is as described above. The cover member 22 in the liquid ejection structure 100A functions as a vibration plate in the liquid ejection head 500 .

[0127] A piezoelectric element 70 having a laminated structure of a lower electrode 71 , a piezoelectric layer 72 , and an upper electrode 73 is disposed on the cover member (vibration plate) 22 . The piezoelectric element 70 is provided above the pressure chamber 62 .

[0128] The upper electrode 73 is an independent electrode patterned corresponding to the shape of the pressure chamber 62. When a driving voltage is applied to the upper electrode 73 of the piezoelectric element 70 disposed at the upper part of the pressure chamber 62 according to input data, the piezoelectric element 70 and the cover member (vibration plate) 22 are deformed, thereby changing the volume of the pressure chamber 62. Due to the pressure change in the pressure chamber 62, the liquid is ejected from the nozzle opening 31 of the nozzle 30 through the nozzle communication channel 61.

[0129] Alternatively, a heater may be provided inside the pressure chamber 62 as a pressure generating element instead of the piezoelectric element, and a driving voltage may be supplied to the heater to generate heat, thereby utilizing the film boiling phenomenon to eject the liquid in the pressure chamber 62 from the nozzle opening 31 .

[0130] [Liquid ejection device]

[0131] The liquid ejecting device of the present invention includes a liquid ejecting head. Hereinafter, an inkjet recording device as an example of the liquid ejecting device will be described.

[0132] The inkjet recording device includes, for example, a plurality of inkjet heads (an example of a liquid ejection head) arranged for each color of ink, an ink storage section storing ink to be supplied to each inkjet head, a paper supply section supplying recording paper, a decurling processing section removing curl of the recording paper, a conveying section arranged opposite to the ejection surface of each inkjet head and conveying the recording paper, an image detection section reading an image recording result, and a paper discharge section discharging the image recorded material to the outside.

[0133] The structures of the inkjet recording device other than the inkjet head are the same as the conventionally known structures, and for example, International Publication No. 2017 / 073526 can be referred to.

[0134] The liquid ejection device of the present invention preferably has a liquid circulation mechanism that circulates the liquid between the liquid ejection head and the liquid tank. Figure 4 The liquid ejection head of the liquid ejection structure 100A shown can circulate liquid between the liquid ejection head and the liquid tank.

[0135] Example

[0136] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

[0137] [Example 1]

[0138] <Formation of the first layer>

[0139] A nozzle substrate having a nozzle formed thereon and a flow path substrate having a liquid flow path formed thereon are bonded together to prepare a Figure 4 The size of the joint body with the same structure is 25mm×35mm.

[0140] Step (a1): Surface treatment

[0141] The bonded body was placed in a vacuum chamber. After the inside of the vacuum chamber was evacuated, oxygen was substituted to generate oxygen plasma. The irradiation conditions of the oxygen plasma were set to an output power of 100 W, a flow rate of 100 mL / min, and an irradiation time of 1 minute.

[0142] Step (b1): Formation of Tantalum Oxide Layer

[0143] Next, the joint body after step (a1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the joint body. Next, tert-butyliminotris(ethylmethylamino)tantalum (TBTEMT) gas is introduced to react the hydroxyl groups formed on the surface of the joint body with TBTEMT. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TBTEMT bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TBTEMT gas and the introduction and exhaust of H2O gas are repeated as a cycle until a predetermined thickness (15nm) is reached, thereby forming a tantalum oxide layer.

[0144] <Formation of the Second Layer>

[0145] Step (c1): Silicon oxide film formation

[0146] Next, a SiO2 layer was formed on the bonded body after step (b1) by CVD (Chemical Vapor Deposition). SiCl4 was used as a raw material and the substrate temperature was set to 100° C. The thickness of the SiO2 layer was set to 30 nm.

[0147] <Formation of Liquid Repellent Layer>

[0148] Step (d1): Hydrophilization treatment

[0149] Next, the bonded body after step (c1) is placed in a vacuum chamber. After the inside of the vacuum chamber is evacuated, it is replaced with oxygen and oxygen plasma is generated. The irradiation conditions of the oxygen plasma are set to an output power of 100 W, a flow rate of 100 mL / min, and an irradiation time of 1 minute.

[0150] Step (e1): Vapor deposition of silane coupling agent

[0151] Next, the bonded body after step (d1) was placed in a vapor deposition chamber. A silane coupling agent was added to the tungsten boat. As the silane coupling agent, KY1901 (a silane coupling agent having a perfluoropolyether structure represented by the following formula 1, manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

[0152] CF3O-(CF2O) n -(CF2CF3O) m -*……(1)

[0153] In Formula 1, m is an integer of 1 to 50, and n is an integer of 1 to 50. * indicates a bonding position to other structures in the compound.

[0154] After the temperature of the tungsten boat reached 180° C., the shutter was opened, and while monitoring the film thickness with a quartz oscillator, the shutter was closed after the film thickness reached 5 nm to vapor-deposit the silane coupling agent.

[0155] Step (f1): Storage in a high temperature and high humidity environment

[0156] Next, in order to promote the hydrolysis reaction of the silane coupling agent and the fusing reaction between the bonded body and the silane coupling agent after step (e1), it was left to stand for 12 hours at a temperature of 60°C and a humidity of 90%. The contact angle of the formed liquid-repellent layer with water was 90° or more. In addition, the contact angle with water was measured at 25°C using a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., LTD.).

[0157] Step (g1): Removal of the liquid-repellent layer formed on the inner wall of the nozzle and the inner wall of the liquid flow path

[0158] Next, an adhesive tape is attached to the surface of the nozzle substrate in the bonded body after step (f1), and the nozzle and the liquid flow path are subjected to oxygen plasma treatment from the surface of the flow path substrate opposite to the surface bonded to the nozzle substrate. Thus, the liquid-repellent layer formed on the inner wall of the nozzle and the inner wall of the liquid flow path is removed, and a liquid ejection structure is obtained.

[0159] [Example 2]

[0160] A liquid ejection structure was obtained in the same manner as in steps (a1) and (c1) to (g1) of Example 1 except that step (b1) of Example 1 was changed to the following step (b2).

[0161] Step (b2): Formation of zirconium oxide layer

[0162] A zirconium oxide layer was formed in the same manner as in the step (b1) except that TBTEMT in the step (b1) was changed to tris(dimethylamino)cyclopentadienylzirconium (ZAC).

[0163] [Example 3]

[0164] A liquid ejection structure was obtained in the same manner as in steps (a1) and (c1) to (g1) of Example 1 except that step (b1) of Example 1 was changed to the following step (b3).

[0165] Step (b3): ​​Formation of titanium oxide layer

[0166] A titanium oxide layer was formed in the same manner as in the step (b1) except that TBTEMT in the step (b1) was changed to tetrakis(dimethylamino)titanium (TDMAT).

[0167] [Example 4]

[0168] A liquid ejection structure was obtained in the same manner as in steps (a1) and (c1) to (g1) of Example 1 except that step (b1) of Example 1 was changed to the following step (b4).

[0169] Step (b4): Formation of hafnium oxide layer

[0170] A hafnium oxide layer was formed in the same manner as in the step (b1) except that TBTEMT in the step (b1) was changed to tetrakis(dimethylamino)hafnium (TDMAHf).

[0171] [Example 5]

[0172] A liquid ejection structure was obtained in the same manner as in steps (a1) to (d1), (f1) and (g1) of Example 1 except that step (e1) of Example 1 was changed to the following step (e2).

[0173] Step (e2): Vapor deposition of silane coupling agent

[0174] In the step (e1), the silane coupling agent was vapor-deposited in the same manner as in the step (e1) except that the film thickness was changed from 5 nm to 10 nm by vapor-depositing the silane coupling agent.

[0175] [Example 6]

[0176] A liquid ejection structure was obtained in the same manner as in steps (a1), (b1), and (d1) to (g1) of Example 1, except that step (c1) of Example 1 was changed to the following step (c2).

[0177] Step (c2): Formation of SiN layer

[0178] The bonded body after step (b1) was subjected to CVD (Chemical Vapor Deposition) to form a SiN layer. Monosilane (SiH4), ammonia and nitrogen were used as raw materials, and the substrate temperature was set to 350° C. The thickness of the SiN layer was set to 30 nm.

[0179] [Example 7]

[0180] A liquid ejection structure was obtained in the same manner as in steps (a1) and (c1) to (g1) of Example 1 except that step (b1) of Example 1 was changed to the following step (b5).

[0181] Step (b5): Formation of Tantalum Oxide Layer

[0182] A tantalum oxide layer was formed in the same manner as in step (b1) except that the thickness was changed to 5 nm.

[0183] [Example 8]

[0184] A liquid ejection structure was obtained in the same manner as in steps (a1) and (c1) to (g1) of Example 1 except that step (b1) of Example 1 was changed to the following step (b6).

[0185] Step (b6): Formation of Tantalum Oxide Layer

[0186] A tantalum oxide layer was formed in the same manner as in step (b1) except that the thickness was changed to 60 nm.

[0187] [Example 9]

[0188] A liquid ejection structure was obtained in the same manner as in steps (a1), (b1), and (d1) to (g1) of Example 1, except that step (c1) of Example 1 was changed to the following step (c3).

[0189] Step (c3): Formation of SiO2 layer

[0190] A SiO 2 layer was formed in the same manner as in step (c1) except that the thickness was changed to 5 nm.

[0191] [Example 10]

[0192] A liquid ejection structure was obtained in the same manner as steps (a1) and (d1) to (g1) of Example 1 except that step (b1) of Example 1 was changed to step (b7) described below, and step (c1) was changed to step (c4) described below.

[0193] Step (b7): Formation of Tantalum Oxide Layer

[0194] A tantalum oxide layer was formed in the same manner as in step (b1) except that the thickness was changed to 30 nm.

[0195] Step (c4): Formation of SiO2 layer

[0196] A SiO 2 layer was formed in the same manner as in step (c1) except that the thickness was changed to 15 nm.

[0197] [Example 11]

[0198] A liquid ejection structure was obtained in the same manner as steps (a1) to (d1) and (g1) of Example 1 except that step (e1) of Example 1 was changed to step (e3) described below and step (f1) was changed to step (f2) described below.

[0199] Step (e3): Vapor deposition of silane coupling agent

[0200] Vapor deposition was performed in the same manner as in step (e1) except that KY1901 in step (e1) was changed to trichloro(1H,1H,2H,2H-heptadecafluorodecyl)silane (FDTS).

[0201] Step (f1): Storage in a high temperature and high humidity environment

[0202] In order to promote the hydrolysis reaction of the silane coupling agent and the fusion reaction between the bonded body and the silane coupling agent after step (e3), the bonded body was left to stand for 4 hours at a temperature of 150° C. The contact angle of the formed liquid-repellent layer with water was 90° or more.

[0203] [Comparative Example 1]

[0204] After step (a1), step (c1) was carried out, and then step (b1) was carried out. In addition, steps (d1) to (g1) were carried out in the same manner as in Example 1 to obtain a liquid ejection structure.

[0205] [Comparative Example 2]

[0206] After step (a1), step (b1) was carried out. Then, the following step (j1) was carried out. In addition, steps (d1) to (g1) were carried out in the same manner as in Example 1 to obtain a liquid ejection structure.

[0207] Step (j1): Formation of plasma polymerized film

[0208] Referring to the examples of Japanese Patent Application Laid-Open No. 2008-105231, a silicone material was plasma polymerized on the bonded body after step (b1) to form a plasma polymerized film. The thickness of the plasma polymerized film was set to 30 nm.

[0209] [Comparative Example 3]

[0210] After the step (a1) was carried out, the following step (k1) was carried out. Otherwise, the steps (c1) to (g1) were carried out in the same manner as in Example 1 to obtain a liquid ejection structure.

[0211] Step (k1): Formation of Tantalum Oxide Layer

[0212] A tantalum oxide layer was formed on the bonded body after step (a1) by sputtering. The tantalum oxide layer was formed only on the surface of the nozzle substrate, and was not formed on the inner wall of the nozzle and the inner wall of the liquid flow path. The thickness of the tantalum oxide layer was set to 15 nm.

[0213] [Comparative Example 4]

[0214] After the step (a1) was carried out, the steps (c1) to (g1) were carried out in the same manner as in Example 1 to obtain a liquid ejection structure. That is, the step (b1) was not carried out.

[0215] [Comparative Example 5]

[0216] After the steps (a1) and (b1) were carried out, the steps (d1) to (g1) were carried out in the same manner as in Example 1 to obtain a liquid ejection structure. That is, the step (c1) was not carried out.

[0217] Next, the abrasion resistance and alkali resistance of the nozzle substrate surface, the alkali resistance of the internal flow path, and the discharge performance were evaluated. The evaluation method is as follows.

[0218] [Example 1A]

[0219] <Formation of the first layer>

[0220] A nozzle substrate having a nozzle formed thereon and a flow path substrate having a liquid flow path formed thereon are bonded together to prepare a Figure 4 The size of the joint body with the same structure is 25mm×35mm.

[0221] Process (p1): Surface treatment

[0222] The bonded body was placed in a vacuum chamber. After the vacuum chamber was evacuated, the air was replaced with oxygen to generate oxygen plasma. The irradiation conditions of the oxygen plasma were set to an output of 30 W, a flow rate of 100 mL / min, and an irradiation time of 30 seconds.

[0223] Step (q1): Formation of hafnium oxide layer

[0224] Next, the bonded body after process (p1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the bonded body. Next, tetrakis(dimethylamino)hafnium (TDMAHf) gas is introduced to react the hydroxyl groups formed on the surface of the bonded body with TDMAHf. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TDMAHf bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TDMAHf gas and the introduction and exhaust of H2O gas are repeated as a cycle until the specified thickness (30hm) is reached, thereby forming a hafnium oxide layer.

[0225] <Formation of the Second Layer>

[0226] Step (r1): Silicon oxide film formation

[0227] Next, the bonded body after process (q1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the bonded body. Next, tri(dimethylamino)silane (TDMAS) gas is introduced to react the hydroxyl groups formed on the surface of the bonded body with TDMAS. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TDMAS bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TDMAS gas and the introduction and exhaust of H2O gas are repeated as a cycle to a specified thickness (1nm), thereby forming a silicon oxide layer.

[0228] <Formation of Liquid Repellent Layer>

[0229] Step (s1): Hydrophilization treatment

[0230] Next, the bonded body after step (r1) is placed in a vacuum chamber. After the inside of the vacuum chamber is evacuated, it is replaced with oxygen to generate oxygen plasma. The irradiation conditions of the oxygen plasma are set to an output power of 30 W, a flow rate of 100 mL / min, and an irradiation time of 30 seconds.

[0231] Step (t1): Vapor deposition of silane coupling agent

[0232] Next, the bonded body after step (s1) was placed in a vapor deposition chamber. A silane coupling agent was added to the tungsten boat. As the silane coupling agent, KY1901 (a silane coupling agent having a perfluoropolyether structure represented by the following formula 1, manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

[0233] CF3O-(CF2O) n -(CF2CF2O) m -*……(1)

[0234] In Formula 1, m is an integer of 1 to 50, and n is an integer of 1 to 50. * indicates a bonding position to other structures in the compound.

[0235] After the temperature of the tungsten boat reached 180° C., the shutter was opened, and while monitoring the film thickness with a quartz oscillator, the shutter was closed after the film thickness reached 5 nm to vapor-deposit the silane coupling agent.

[0236] Process (u1): Storage in a high temperature and high humidity environment

[0237] Next, in order to promote the hydrolysis reaction of the silane coupling agent and the fusing reaction between the bonded body and the silane coupling agent after step (t1), it was left to stand for 12 hours at a temperature of 60°C and a humidity of 60%. The contact angle of the formed liquid-repellent layer with water was 90° or more. In addition, the contact angle with water was measured at 25°C using a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., LTD.).

[0238] Step (v1): Removal of the liquid-repellent layer formed on the inner wall of the nozzle and the inner wall of the liquid flow path

[0239] Next, an adhesive tape was attached to the surface of the nozzle substrate in the bonded body after step (u1), and the nozzle and the liquid flow path were subjected to oxygen plasma treatment from the surface of the flow path substrate opposite to the surface bonded to the nozzle substrate. Thus, the liquid-repellent layer formed on the inner wall of the nozzle and the inner wall of the liquid flow path was removed, and a liquid ejection structure was obtained.

[0240] [Example 2A]

[0241] A liquid ejection structure was obtained in the same manner as in steps (p1) and (r1) to (v1) of Example 1A, except that step (q1) of Example 1A was changed to the following step (q2).

[0242] Step (q2): Formation of hafnium oxide layer

[0243] Next, the bonded body after process (p1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the bonded body. Next, tetrakis(dimethylamino)hafnium (TDMAHf) gas is introduced to react the hydroxyl groups formed on the surface of the bonded body with TDMAHf. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TDMAHf bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TDMAHf gas and the introduction and exhaust of H2O gas are repeated as a cycle until a predetermined thickness (15nm) is reached, thereby forming a hafnium oxide layer.

[0244] [Example 3A]

[0245] A liquid ejection structure was obtained in the same manner as in steps (p1) and (r1) to (v1) of Example 1A, except that step (q1) of Example 1A was changed to the following step (q3).

[0246] Step (q3): Formation of zirconium oxide layer

[0247] A zirconium oxide layer was formed in the same manner as in the step (q1) except that TDMAHf in the step (q1) was changed to tris(dimethylamino)cyclopentadienylzirconium (ZAC).

[0248] [Example 4A]

[0249] A liquid ejection structure was obtained in the same manner as in steps (p1) and (r1) to (v1) of Example 1A, except that step (q1) of Example 1A was changed to the following step (q4).

[0250] Step (q4): Formation of Tantalum Oxide Layer

[0251] A tantalum oxide layer was formed in the same manner as in the step (q1) except that TDMAHf in the step (q1) was changed to tert-butyliminotris(ethylmethylamino)tantalum (TBTEMT).

[0252] [Example 5A]

[0253] A liquid ejection structure was obtained in the same manner as in steps (p1) and (r1) to (v1) of Example 1A, except that step (q1) of Example 1A was changed to the following step (q5).

[0254] Step (q5): Formation of titanium oxide layer

[0255] A titanium oxide layer was formed in the same manner as in the step (q1) except that TDMAHf in the step (q1) was changed to tetrakis(dimethylamino)titanium (TDMAT).

[0256] [Example 6A]

[0257] A liquid ejection structure was obtained in the same manner as steps (p1), (q1), (s1) to (v1) of Example 1A except that step (r1) of Example 1A was changed to the following step (r2).

[0258] Step (r2): Silicon oxide film formation

[0259] The bonded body after process (q1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the bonded body. Next, tri(dimethylamino)silane (TDMAS) gas is introduced to react the hydroxyl groups formed on the surface of the bonded body with TDMAS. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TDMAS bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TDMAS gas and the introduction and exhaust of H2O gas are repeated as a cycle to a specified thickness (5nm), thereby forming a silicon oxide layer.

[0260] [Example 7A]

[0261] A liquid ejection structure was obtained in the same manner as steps (p1), (q1), (s1) to (v1) of Example 1A except that step (r1) of Example 1A was changed to the following step (r3).

[0262] Step (r3): Silicon oxide film formation

[0263] The bonded body after process (q1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the bonded body. Next, tri(dimethylamino)silane (TDMAS) gas is introduced to react the hydroxyl groups formed on the surface of the bonded body with TDMAS. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TDMAS bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TDMAS gas and the introduction and exhaust of H2O gas are repeated as a cycle to a specified thickness (30nm), thereby forming a silicon oxide layer.

[0264] [Example 8A]

[0265] A liquid ejection structure was obtained in the same manner as steps (p1), (q1), (s1) to (v1) of Example 1A except that step (r1) of Example 1A was changed to the following step (r4).

[0266] Step (r4): Silicon oxide film formation

[0267] The bonded body after process (q1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the bonded body. Next, tri(dimethylamino)silane (TDMAS) gas is introduced to react the hydroxyl groups formed on the surface of the bonded body with TDMAS. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TDMAS bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TDMAS gas and the introduction and exhaust of H2O gas are repeated as a cycle to a specified thickness (120nm), thereby forming a silicon oxide layer.

[0268] [Example 9A]

[0269] A liquid ejection structure was obtained in the same manner as steps (p1), (q1), (s1) to (v1) of Example 1A except that step (r1) of Example 1A was changed to the following step (r5).

[0270] Step (r5): Silicon oxide film formation

[0271] The bonded body after process (q1) is arranged in an ALD (Atomic Layer Deposition) chamber, and H2O gas is introduced to form hydroxyl groups on the surface of the bonded body. Next, tri(dimethylamino)silane (TDMAS) gas is introduced to react the hydroxyl groups formed on the surface of the bonded body with TDMAS. Then, the remaining gas is exhausted. Next, H2O gas is introduced to react the TDMAS bonded to the hydroxyl groups in the previous reaction with H2O. Then, the remaining gas is exhausted. Then, the introduction and exhaust of TDMAS gas and the introduction and exhaust of H2O gas are repeated as a cycle to a specified thickness (2.5nm), thereby forming a silicon oxide layer.

[0272] -Evaluation Methods of Examples 1 to 11 and Comparative Examples 1 to 5-

[0273] <Alkali resistance of nozzle substrate surface>

[0274] A black ink described in

[0270] of Japanese Patent Gazette No. 2018-35270 was prepared. An ink in which sodium hydroxide was added to the prepared black ink and the pH was adjusted to 10 was used as an evaluation ink. The produced liquid ejection structure was immersed in the evaluation ink and allowed to stand in a constant temperature bath set at 60°C. After 200 hours, the static contact angle of the nozzle substrate surface was measured using the newly prepared evaluation ink. The contact angle with the ink was measured at 25°C using a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., LTD.). Alkali resistance was evaluated based on the contact angle. The evaluation criteria are as follows. It can be said that the larger the contact angle, the better the alkali resistance.

[0275] 5: The contact angle is 80° or more and less than 90°.

[0276] 4: The contact angle is 70° or more and less than 80°.

[0277] 3: The contact angle is 60° or more and less than 70°.

[0278] 2: The contact angle is 50° or more and less than 60°.

[0279] 1: The contact angle is less than 50°.

[0280] <Alkali resistance of internal flow path>

[0281] Since the contact angle of the internal flow path cannot be measured directly, the following method was used instead for evaluation.

[0282] First, in the embodiment and the comparative example, the process (f1) in the manufacture of the liquid ejection structure is respectively carried out to prepare a bonded body after the process (f1). Then, the surface of the nozzle substrate is treated with oxygen plasma to remove the liquid-repellent layer on the surface of the nozzle substrate, thereby obtaining an evaluation structure. The surface state of the nozzle substrate from which the liquid-repellent layer is removed is the same as the surface state of the internal flow path in the liquid ejection structure.

[0283] The prepared evaluation structure was immersed in the evaluation ink and allowed to stand in a constant temperature bath set at 60°C. The surface roughness Ra of the nozzle substrate in the evaluation structure was measured before and after 600 hours of immersion. The surface roughness Ra was measured using an atomic force microscope (product name "Dimension icon with ScanAsyst", manufactured by BRUKER), and the average value of 5 locations was measured. Based on the degree of change in the surface roughness Ra, the alkali resistance was evaluated. The degree of change is represented by the ratio (times) of the surface roughness Ra after immersion to the surface roughness Ra before immersion. The evaluation criteria are as follows. It can be said that the smaller the degree of change in the surface roughness Ra, the better the alkali resistance.

[0284] 5: The degree of change is less than 1.2 times.

[0285] 4: The degree of change is 1.2 times or more and less than 1.5 times.

[0286] 3: The degree of change is 1.5 times or more and less than 3 times.

[0287] 2: The degree of change is 3 times or more and less than 5 times.

[0288] 1: The degree of change is 5 times or more.

[0289] <Wipe resistance of nozzle substrate surface>

[0290] The evaluation ink was dropped onto a wiping member (product name "TORCY", manufactured by TORAY INDUSTRIES, INC.). The surface of the nozzle substrate in the manufactured liquid ejection structure was pressed onto the dropped surface at a constant pressure of 40 kPa, and it was made to slide back and forth. After sliding it back and forth 10,000 times, the static contact angle of the nozzle substrate surface was measured using the newly prepared evaluation ink. The contact angle with the ink was measured at 25°C using a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., LTD.). The wipe resistance was evaluated based on the contact angle. The evaluation criteria are as follows. The larger the contact angle, the better the wipe resistance.

[0291] 5: The contact angle is 80° or more and less than 90°.

[0292] 4: The contact angle is 70° or more and less than 80°.

[0293] 3: The contact angle is 60° or more and less than 70°.

[0294] 2: The contact angle is 50° or more and less than 60°.

[0295] 1: The contact angle is less than 50°.

[0296] <Ejection property>

[0297] A wiping member (product name "TORCY", manufactured by TORAY INDUSTRIES, INC.) was pressed against the surface of the nozzle substrate in the produced liquid ejection structure at a constant pressure of 40 kPa and slid back and forth 10 times.

[0298] Next, the vibration plate was bonded to the liquid ejection structure, and a piezoelectric element was arranged to produce a liquid ejection head. The produced liquid ejection head was assembled into an inkjet recording experimental device.

[0299] Before starting the inkjet recording experimental device, a 15-minute ink-based liquid circulation was performed to remove the ink remaining in the ink contact part of the device. Then, the device was started continuously for 1 hour and it was made to eject ink. After 1 hour, the wiping member (product name "TORCY", manufactured by TORAY INDUS TRIES, INC.) was pressed on the surface of the nozzle substrate with a constant pressure of 40kPa and slid back and forth 50 times. After repeating 50 consecutive ejection and sliding operations, the number of nozzles causing poor ejection was counted. Poor ejection includes a state where ink is not ejected at all (no ejection) and a state where ink is ejected or not ejected (intermittent no ejection). The ejection property was evaluated based on the number of nozzles causing poor ejection. The evaluation criteria are as follows. The fewer the number of nozzles causing poor ejection, the better the ejection property. In addition, 2048 nozzles are formed in the liquid ejection structure.

[0300] 5: The number of nozzles causing ejection failure is 0.

[0301] 4: The number of nozzles causing ejection failure is 1 or 2.

[0302] 3: The number of nozzles causing ejection failure is 3 to 9.

[0303] 2: The number of nozzles causing ejection failure is 10 to 19.

[0304] 1: The number of nozzles causing ejection failure is 20 or more.

[0305] -Evaluation Methods of Examples 1A to 9A-

[0306] <Alkali resistance of nozzle substrate surface>

[0307] A black ink described in

[0270] of Japanese Patent Gazette No. 2018-35270 was prepared. An ink in which sodium hydroxide was added to the prepared black ink and the pH was adjusted to 10 was used as an evaluation ink. The produced liquid ejection structure was immersed in the evaluation ink and allowed to stand in a constant temperature bath set at 60°C. After 400 hours, the static contact angle of the nozzle substrate surface was measured using the newly prepared evaluation ink. The contact angle with the ink was measured at 25°C using a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., LTD.). Alkali resistance was evaluated based on the contact angle. The evaluation criteria are as follows. It can be said that the larger the contact angle, the better the alkali resistance.

[0308] 5: The contact angle is 80° or more and less than 90°.

[0309] 4: The contact angle is 70° or more and less than 80°.

[0310] 3: The contact angle is 60° or more and less than 70°.

[0311] 2: The contact angle is 50° or more and less than 60°.

[0312] 1: The contact angle is less than 50°.

[0313] <Alkali resistance of internal flow path>

[0314] Since the contact angle of the internal flow path cannot be measured directly, the following method was used instead for evaluation.

[0315] First, in the embodiment and the comparative example, the process (f1) in the manufacture of the liquid ejection structure is respectively carried out to prepare a bonded body after the process (f1). Then, the surface of the nozzle substrate is treated with oxygen plasma to remove the liquid-repellent layer on the surface of the nozzle substrate, thereby obtaining an evaluation structure. The surface state of the nozzle substrate from which the liquid-repellent layer is removed is the same as the surface state of the internal flow path in the liquid ejection structure.

[0316] The prepared evaluation structure was immersed in the evaluation ink and allowed to stand in a constant temperature bath set at 60°C. The surface roughness Ra of the nozzle substrate in the evaluation structure was measured before and after 1000 hours of immersion. The surface roughness Ra was measured using an atomic force microscope (product name "Dimension icon with ScanAsyst", manufactured by BRUKER), and the average value of 5 locations was measured. Based on the degree of change in the surface roughness Ra, the alkali resistance was evaluated. The degree of change is represented by the ratio (times) of the surface roughness Ra after immersion to the surface roughness Ra before immersion. The evaluation criteria are as follows. It can be said that the smaller the degree of change in the surface roughness Ra, the better the alkali resistance.

[0317] 5: The degree of change is less than 1.2 times.

[0318] 4: The degree of change is 1.2 times or more and less than 1.5 times.

[0319] 3: The degree of change is 1.5 times or more and less than 3 times.

[0320] 2: The degree of change is 3 times or more and less than 5 times.

[0321] 1: The degree of change is 5 times or more.

[0322] <Wipe resistance of nozzle substrate surface>

[0323] The evaluation ink was dropped onto a wiping part (product name "TORCY", manufactured by TORAY INDUSTRIES, INC.). The surface of the nozzle substrate in the manufactured liquid ejection structure was pressed onto the dropped surface at a constant pressure of 40 kPa, and it was made to slide back and forth. After sliding it back and forth 20,000 times, the static contact angle of the nozzle substrate surface was measured using the newly prepared evaluation ink. The contact angle with the ink was measured at 25°C using a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., LTD.). The wipe resistance was evaluated based on the contact angle. The evaluation criteria are as follows. The larger the contact angle, the better the wipe resistance.

[0324] 5: The contact angle is 80° or more and less than 90°.

[0325] 4: The contact angle is 70° or more and less than 80°.

[0326] 3: The contact angle is 60° or more and less than 70°.

[0327] 2: The contact angle is 50° or more and less than 60°.

[0328] 1: The contact angle is less than 50°.

[0329] <Ejection property>

[0330] A wiping member (product name "TORCY", manufactured by TORAY INDUSTRIES, INC.) was pressed against the surface of the nozzle substrate in the produced liquid ejection structure at a constant pressure of 40 kPa and slid back and forth 10 times.

[0331] Next, the vibration plate was bonded to the liquid ejection structure, and a piezoelectric element was arranged to produce a liquid ejection head. The produced liquid ejection head was assembled into an inkjet recording experimental device.

[0332] Before starting the inkjet recording experimental device, a 15-minute ink-based liquid circulation was performed to remove the ink remaining in the ink contact part of the device. Then, the device was started continuously for 1 hour and it was made to eject ink. After 1 hour, the wiping member (product name "TORCY", manufactured by TORAY INDUS TRIES, INC.) was pressed on the surface of the nozzle substrate with a constant pressure of 40kPa and slid back and forth 50 times. After repeating 50 consecutive ejection and sliding operations, the number of nozzles causing poor ejection was counted. Poor ejection includes a state where ink is not ejected at all (no ejection) and a state where ink is ejected or not ejected (intermittent no ejection). The ejection property was evaluated based on the number of nozzles causing poor ejection. The evaluation criteria are as follows. The fewer the number of nozzles causing poor ejection, the better the ejection property. In addition, 2048 nozzles are formed in the liquid ejection structure.

[0333] 5: The number of nozzles causing ejection failure is 0.

[0334] 4: The number of nozzles causing ejection failure is 1 or 2.

[0335] 3: The number of nozzles causing ejection failure is 3 to 9.

[0336] 2: The number of nozzles causing ejection failure is 10 to 19.

[0337] 1: The number of nozzles causing ejection failure is 20 or more.

[0338] The evaluation results are shown in Tables 1 and 2. In Tables 1 and 2, the first layer refers to the bottom layer provided in the nozzle substrate and the internal flow path. The second layer refers to a layer provided on the first layer. The liquid-repellent layer is a layer provided on the second layer in the ejection surface of the nozzle substrate. Regarding the liquid-repellent layer, whether it has a perfluoropolyether structure (PFPE structure) is recorded. Regarding the first layer and the second layer, the types and thicknesses of the components constituting the layers are recorded. In Tables 1 and 2, "second layer / first layer" refers to the ratio of the thickness of the second layer to the thickness of the first layer.

[0339]

[0340] As shown in Table 1, in Examples 1 to 11, the liquid ejection structure comprises a nozzle substrate formed with a nozzle for ejecting liquid, and a flow path substrate formed with a liquid flow path connected to the nozzle, and the ejection surface of the nozzle substrate has a first layer, a second layer, and a liquid-repellent layer in sequence, and the inner wall of the liquid flow path has a first layer and a second layer in sequence, the first layer is a layer comprising at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and the second layer is a layer comprising at least one selected from the group consisting of SiO2, SiC, SiN, SiCN, and SiON, so it can be seen that the ejection surface has excellent abrasion resistance, and the ejection surface and the internal flow path have excellent alkali resistance.

[0341] On the other hand, in Comparative Example 1, the first layer is a SiO2 layer and the second layer is a tantalum oxide layer on the surface of the nozzle substrate and the inner wall of the internal flow path, so it is found that the abrasion resistance of the ejection surface is poor.

[0342] In Comparative Example 2, since the second layer on both the surface of the nozzle substrate and the inner wall of the internal flow path is a plasma polymerized film of a silicone material, it is found that the abrasion resistance of the ejection surface is poor.

[0343] In Comparative Example 3, only the SiO 2 layer is provided on the inner wall of the internal flow path, and therefore it is found that the alkali resistance of the internal flow path is poor.

[0344] In Comparative Example 4, since only the SiO 2 layer is provided on the surface of the nozzle substrate and the inner wall of the internal flow path, it is found that the alkali resistance of the internal flow path is poor.

[0345] In Comparative Example 5, since only the tantalum oxide layer is provided on the surface of the nozzle substrate and the inner wall of the internal flow path, it is found that the abrasion resistance of the ejection surface is poor.

[0346] Furthermore, in Examples 1 and 2, since the first layer is a layer of tantalum oxide or zirconium oxide, it is found that the alkali resistance of the internal flow path is superior to that of Examples 3 and 4.

[0347] In Example 1, since the second layer is a SiO 2 layer, it is found that the abrasion resistance of the ejection surface is superior to that of Example 6.

[0348] In Example 1, the thickness of the first layer is 10 nm to 50 nm, so the alkali resistance of the ejection surface and the internal flow path is excellent compared with Example 7, and the abrasion resistance of the ejection surface is excellent compared with Example 8, and the alkali resistance of the ejection surface and the internal flow path is excellent.

[0349] In Example 1, since the thickness of the second layer is 10 nm or more, it is found that the abrasion resistance of the ejection surface is superior to that of Example 9.

[0350] In Example 1, since the ratio of the thickness of the second layer to the thickness of the first layer is 0.8 or more, it is found that the abrasion resistance of the ejection surface is superior to that of Example 10.

[0351] In Example 1, since the liquid-repellent layer contains a silicon compound having a perfluoropolyether structure, it is found that the abrasion resistance of the ejection surface is superior to that of Example 11.

[0352] In Example 1, since the thickness of the liquid-repellent layer is 3 nm to 8 nm, it is found that the discharge property is superior to that of Example 5.

[0353]

[0354] As shown in Table 2, in Examples 1A to 9A, the liquid ejection structure comprises a nozzle substrate having a nozzle for ejecting liquid, and a flow path substrate having a liquid flow path connected to the nozzle, the ejection surface of the nozzle substrate comprises a first layer, a second layer, and a liquid-repellent layer in sequence, and the inner wall of the liquid flow path comprises a first layer and a second layer in sequence, the first layer is a layer comprising at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and the second layer is a layer comprising at least one selected from the group consisting of SiO2, SiC, SiN, SiCN, and SiON, therefore, it can be seen that the ejection surface has excellent abrasion resistance, and the ejection surface and the internal flow path have excellent alkali resistance.

[0355] Furthermore, in Example 1A, Example 3A, and Example 4A, since the first layer is a layer of tantalum oxide, zirconium oxide, or hafnium oxide, it is found that the alkali resistance of the internal flow path is superior to that of Example 5A.

[0356] Furthermore, in Example 7A, since the thickness of the second layer is 10 nm to 100 nm, it is found that the abrasion resistance and alkali resistance of the ejection surface are superior to those of Example 8A.

[0357] In Example 1A and Example 9A, the thickness of the second layer is 0.3nm to 3nm, so it can be seen that the abrasion resistance of the ejection surface is excellent compared with Example 6A. In addition, in Example 1A, the thickness of the second layer is 0.3nm to 2nm, so it can be seen that the abrasion resistance of the ejection surface is more excellent than that of Example 9A.

[0358] In addition, the disclosure of Japanese Patent Application No. 2020-061103 filed on March 30, 2020 is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications, and technical standards described in this specification are incorporated into this specification by reference to the same extent as if each document, patent application, and technical standard were specifically and individually described as being incorporated by reference.

Claims

1. A liquid ejection structure comprising a nozzle substrate on which a nozzle for ejecting liquid is formed, and a flow path substrate on which a liquid flow path communicating with the nozzle is formed, The nozzle substrate has a first layer, a second layer and a liquid-repellent layer in sequence on the ejection surface thereof. The first layer and the second layer are sequentially provided on the inner wall of the liquid flow path, The first layer is a layer including at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, The second layer is a layer comprising at least one selected from the group consisting of SiO2, SiC, SiN, SiCN and SiON, The thickness of the second layer is 0.3nm-3nm, and the ratio of the thickness of the second layer to the thickness of the first layer is 0.006-0.3; or, the thickness of the second layer is 10nm-100nm, and the ratio of the thickness of the second layer to the thickness of the first layer is 0.006-6.

2. The liquid ejection structure according to claim 1, wherein: The first layer is a layer of tantalum oxide, zirconium oxide, or hafnium oxide.

3. The liquid ejection structure according to claim 1 or 2, wherein: The second layer is a SiO2 layer.

4. The liquid ejection structure according to claim 1 or 2, wherein: The thickness of the first layer is 10 nm to 50 nm, and the ratio of the thickness of the second layer to the thickness of the first layer is 0.006 to 6.

5. The liquid ejection structure according to claim 1 or 2, wherein: The thickness of the second layer is 0.3 nm to 2 nm, and the ratio of the thickness of the second layer to the thickness of the first layer is 0.006 to 0.

3.

6. The liquid ejection structure according to claim 1 or 2, wherein: The liquid-repellent layer includes a compound having a perfluoropolyether structure.

7. The liquid ejection structure according to claim 1 or 2, wherein: The thickness of the liquid-repellent layer is 3 nm to 8 nm.

8. The liquid ejection structure according to claim 1 or 2, wherein: The liquid flow path has a circulation flow path for circulating the liquid. 9 . A liquid ejection head comprising the liquid ejection structure according to claim 1 . 10 . A liquid ejecting device comprising the liquid ejecting head according to claim 9 .

11. The liquid ejection device according to claim 10, wherein: A liquid circulation mechanism is provided for circulating liquid between the liquid ejection head according to claim 9 and the liquid tank.

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