Liquid discharge head

Abstract

To provide a liquid discharge head that is configured so that an adhesive has high initial adhesion to an organic film and the adhesive does not deteriorate in adhesion even after the adhesive is immersed in ink.SOLUTION: The liquid discharge head comprises a discharge port for discharging liquid, a pressure chamber whose pressure acts on liquid discharged from the discharge port, a flow passage communicating with the pressure chamber, a substrate forming the flow passage, and an organic film constituting a portion of a wall surface of the flow passage, which prevents liquid in the flow passage from vibrating. The organic film is made to adhere to the substrate with an adhesive, and the organic film is joined to the adhesive through a siloxane linkage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a liquid ejection head. [Background technology]

[0002] Flow path members, which are minute structures, are used, for example, in the liquid ejection heads of inkjet recording devices. Inkjet recording devices are recording devices that eject ink from nozzles in a liquid ejection head to form characters and images on a medium. For example, in piezoelectric inkjet recording devices, a piezoelectric element is installed via a vibration plate in a position facing a pressure chamber that communicates with the nozzles that eject the liquid. Applying a voltage to the piezoelectric element displaces the piezoelectric element and the vibration plate, changing the volume of the pressure chamber and ejecting liquid from the nozzle. This vibration of the vibration plate is transmitted to adjacent nozzles through the liquid in the liquid flow path, a phenomenon known as crosstalk, which can cause poor ejection of liquid from adjacent nozzles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 045112 Summary of the Invention [Problem to be solved by the invention]

[0004] For this reason, one method is to install a damper within the flow path member so that it faces the piezoelectric element. This damper must be ink-resistant, heat-resistant enough to withstand the adhesive's curing temperature, and have an elastic modulus and film thickness suitable for functioning as a damper film. Materials that satisfy these characteristics include polyimide and LCP, but they often have difficulty bonding. Furthermore, because this damper is installed within the flow path member that is bonded to the recording element substrate, it must be bonded using an adhesive in a pre-process. However, there are issues with the reliability of the bond between the adhesive and the damper film.

[0005] Patent Document 1 presents a technology that uses a film containing a heat-resistant resin, for example, polyimide, and a resin composition, for example, benzocyclobutene (BCB), and that by performing a surface treatment such as plasma treatment on the film containing the heat-resistant resin, an ester bond is generated between the film and the resin composition, thereby improving adhesion.

[0006] However, when the present inventors investigated the adhesiveness of the member having the ester bond described in Patent Document 1, they confirmed that the bond between the organic film serving as a damper film and the adhesive deteriorates over time when immersed in ink. Therefore, the adhesion is insufficient for use in an inkjet recording device that is constantly in contact with ink, and there is a risk that the organic film and the adhesive will peel off in a short period of time. The present disclosure is directed to a liquid ejection head in which the initial adhesive strength of an adhesive to an organic film is high and the adhesive strength is not likely to decrease even when the adhesive is immersed in ink. [Means for solving the problem]

[0007] The present disclosure relates to a liquid ejection head, The liquid ejection head includes: a discharge port for discharging a liquid; a pressure chamber in which pressure acts on the liquid discharged from the discharge port; a flow path communicating with the pressure chamber; a substrate on which the flow channel is formed; an organic film that constitutes a part of a wall surface of the flow channel and that suppresses vibration of the liquid in the flow channel; the organic film is adhered to the substrate with an adhesive; The liquid ejection head is such that the organic film and the adhesive are bonded via a siloxane bond. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a liquid ejection head in which the initial adhesive strength of the adhesive to the organic film is high and the adhesive strength is not likely to decrease even when immersed in ink. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic cross-sectional view of a liquid ejection head. [Figure 2] Schematic diagram of die shear measurement. [Figure 3] A diagram showing an example of the organic film formation process DETAILED DESCRIPTION OF THE INVENTION

[0010] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the upper and lower limits, which are the endpoints, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following embodiments do not limit the present disclosure, and not all combinations of features described in the present embodiments are necessarily essential to the present disclosure. Note that the same reference numerals may be used to refer to the same components.

[0012] <Liquid ejection head> 1 is a schematic cross-sectional view of a liquid ejection head including a flow path member 10 according to a first embodiment. The liquid ejection head 1 is manufactured by bonding the flow path member 10 to a nozzle plate 2 including ejection ports 3 for ejecting liquid. The liquid ejection head 1 is suitable for use as an inkjet recording head mounted in a recording device that ejects ink to form characters and images on a medium.

[0013] The flow path member 10 is formed by bonding a first substrate 11 having a recess 12 and a first flow path 13 to a second substrate 21 for forming a second flow path 23 that communicates with an organic film layer 25. Therefore, the liquid ejection head includes a substrate that forms the flow path 13. The first substrate 11 has an organic film 25 that functions as a damper film for suppressing vibration of the liquid, formed so as to cover the recess 12. In addition to the second flow path 23, the second substrate 21 has an ejection element 4 that generates pressure to eject the liquid from the ejection port 3, and a pressure chamber 6 in which the pressure generated by the ejection element 4 acts on the liquid.

[0014] Then, the first substrate 11 and the second substrate 21 are joined to form the flow path member 10, and the liquid that has flowed through the first flow path 13 is supplied to the pressure chamber 6 via the second flow path 23. The pressure generated by the ejection element 4 acts on the liquid supplied to the pressure chamber 6, causing the liquid to be ejected from the ejection port 3.

[0015] The ejection element 4 may be a piezoelectric element that is displaced by the application of a voltage. Alternatively, the ejection element 4 may be a thermoelectric conversion element that generates heat by the piezoelectric element. When the ejection element 4 is a piezoelectric element, it is preferable to have a vibration plate 5 between the piezoelectric element and the pressure chamber 6. By having the vibration plate 5, the displacement of the piezoelectric element is more easily transmitted to the liquid in the pressure chamber 6. In an inkjet recording head equipped with a piezoelectric element, as described above, the vibration is transmitted to adjacent ejection ports through the liquid in the flow path, which is called crosstalk, and this can sometimes cause poor ejection of liquid from adjacent ejection ports.

[0016] The flow path member 10 has an organic film 25 that can function as a damper film. When vibrations of the ejection elements 4 or the diaphragm 5 are transmitted to the organic film 25 via the liquid in the second flow path 23, the organic film 25 acts as a damper, thereby suppressing the vibrations of the liquid. Therefore, crosstalk can be suppressed by the organic film 25. In other words, the liquid ejection head according to the present disclosure is suitable for use when the ejection elements that are prone to crosstalk are piezoelectric elements. In addition, the convex portion 12 is provided with an air communication hole 35 for communication with the atmosphere.

[0017] Therefore, for example, the liquid ejection head 1 includes an ejection port 3 for ejecting liquid, a pressure chamber 6 in which pressure acts on the liquid ejected from the ejection port 3, and a flow path 13 that communicates with the pressure chamber 6. The liquid ejection head 1 also includes an organic film 25 that forms part of the wall surface of the flow path 13 and suppresses vibration of the liquid inside the flow path 13. The liquid ejection head 1 also includes an ejection element 4 that generates pressure, and the ejection element 4 is preferably a piezoelectric element.

[0018] The organic film 25 is bonded to the substrate with an adhesive. For example, in Fig. 1, the first substrate 11 and the second substrate 21 are bonded via the organic film 25, which satisfies, for example, one or both of the following (A) and (B): (A) The first substrate 11 and the organic film 25 are bonded together with an adhesive. (B) The second substrate 21 and the organic film 25 are bonded together with an adhesive. However, the present invention is not limited to this embodiment, and it is sufficient that the organic film is adhered to the substrate with an adhesive.

[0019] The organic film and the adhesive are bonded via a siloxane bond. The inventors have discovered that bonding the organic film and the adhesive via a siloxane bond increases the initial adhesive strength of the adhesive to the organic film and makes the adhesive strength less likely to decrease even when immersed in ink. This is thought to be due to the higher water and oil repellency of the siloxane bond compared to other bonds such as ester bonds, resulting in improved durability against ink. Therefore, the ink is not particularly limited, and both water-based inks and organic inks can be used. Examples of organic inks include acrylic inks.

[0020] <About organic films> The organic film 25 is required to have ink resistance and heat resistance above the thermosetting temperature of the adhesive. Possible materials for the organic film 25 include super engineering plastics such as polyimide, epoxy resin, liquid crystal polymer resin (LCP), polyether ether ketone (PEEK), and polyetherimide (PEI). While polyamide is difficult to use with inks containing acrylic monomers due to its ink resistance, it can be used with water-based inks such as latex inks. The organic film 25 preferably contains at least one selected from the group consisting of polyimide and epoxy resin. It is more preferable that the organic film 25 contains polyimide.

[0021] It is preferable that functional groups are generated on the surface of the organic film, as this increases the reactivity with the silane agent described below and enhances the bonding strength between the organic film and the silane agent. Methods for increasing the functional groups on the surface of the organic film include plasma treatment and chemical treatment as shown in Patent Document 1. It is preferable that the part of the organic film that comes into contact with the adhesive is plasma treated. Also, In addition to forming a silane agent layer by generating functional groups on the film surface, an organic film may be used in which a silane agent is added to the resin in advance so that the silane agent reacts with the functional groups in the resin on the film surface after the solvent evaporates or after curing.

[0022] Furthermore, when the organic film is used as a damper film, in order to exhibit damper performance, the modulus of elasticity of the organic film is preferably 15 GPa or less, more preferably 10 GPa or less. Although there is no particular lower limit, the modulus of elasticity of the organic film is preferably 3 GPa or more, more preferably 4 GPa or more. Furthermore, from the viewpoint of exhibiting damping performance, the thickness of the organic film is preferably 10 μm or less, more preferably 7 μm or less. Although there is no particular lower limit, the thickness of the organic film is preferably 1 μm or more, more preferably 1.5 μm or more.

[0023] As a result of extensive research by the present inventors, polyimide is particularly preferable as the organic film from the viewpoints of high ink resistance against many types of ink, elastic modulus, and film formability to form a desired film thickness. Monomers that can be used to prepare polyimide include diamines, triamines, carboxylic dianhydrides, and carboxylic trianhydrides.

[0024] Diamines include phenylenediamine and its derivatives, diaminobiphenyl compounds and their derivatives, diaminodiphenyl compounds and their derivatives, diaminotriphenyl compounds and their derivatives, diaminonaphthalene and its derivatives, aminophenylaminoindan and its derivatives, diaminotetraphenyl compounds and their derivatives, diaminohexaphenyl compounds and their derivatives, and cardo-type fluorenediamine derivatives.

[0025] Specifically, the diamine may be 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminofuran), (phenyl) sulfide, 4,4'-diaminobenzanilide, dimethylbenzidine, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, oxydianiline, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-di Aminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2 ,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diaminodiphenyl sulfoxide, etc.

[0026] Other diamines include 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, and 1,3-bis(4-aminophenoxy)benzene. benzene, etc. 3,3'-bis(3-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, 9,9-bis(4-aminophenyl)fluorene, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, etc. These diamines may be used alone or in combination of two or more.

[0027] Carboxylic acid anhydrides include pyromellitic dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2,6,6-biphenyltetracarboxylic dianhydride, and 2,2-bis(2,3-dicarboxyphenyl)methane dianhydride. (3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, bis(3, 4-dicarboxyphenyl) ether dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, oxydiphthalic anhydride, 4,4-(p-phenylenedioxy)diphthalic dianhydride, 4,4-(m-phenylenedioxy)diphthalic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride anhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, 9,9-bisphthalic acid fluorene anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, and the like. Examples of the aliphatic tetracarboxylic dianhydride include ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1,2,3,4-cyclohexane tetracarboxylic dianhydride, etc. These may be used alone or in combination of two or more.

[0028] The polyimide is preferably an imide of polyamic acid obtained by diamine and carboxylic acid anhydride. The polyamic acid may be commercially available, for example, polyamic acid solution PI2610 (trade name: manufactured by HD Microsystems, Inc.).

[0029] The epoxy resin is not particularly limited, and known epoxy resins can be used. The epoxy resin is preferably a photosensitive epoxy resin, and is preferably a cured product of an epoxy resin composition containing a bifunctional or higher functional epoxy resin and a photoacid generator. Examples of bifunctional or higher functional epoxy resins that can be used include EPICLON N695 (DIC Corporation) and jER 1009F (Mitsubishi Chemical Corporation).

[0030] <About silane agents> A silane agent may be used between the organic film and the adhesive. The silane agent is, for example, a silane coupling agent. The silane agent is not particularly limited, but it should have a functional group that can react with the organic film described above. The above-mentioned is more preferable because it generates a chemical bond between the organic film and the silane agent, which leads to an increase in adhesive strength. Therefore, it is preferable that the adhesion between the organic film and the adhesive includes bonding via a silane agent.

[0031] More specifically, it is preferable that the liquid ejection head contains a bond represented by the following formula (1) in addition to a siloxane bond between the organic film and the adhesive. ―C1-X-C2― ···(1) In the formula (1), X is at least one selected from the group consisting of -CO-NH-, -CH-CHOH-CH-O-CO-CH-CH-, -CHOH-CH-N-, -CH-(CH-O-CH)-CH-, -CO-O-, -CO-S-, -O-, and -NH-CO-O-; n is the average number of moles added and represents an integer of 1 to 200 (preferably 10 to 200), C1 and C2 are each independently a carbon atom. X is more preferably at least one selected from the group consisting of -CO-NH-, -CH2-CHOH-CH2-O-CO-CH2-CH2-, -CHOH-CH2-N-, and -CH2-(CH2-O-CH2)n-CH2-. The method for confirming the bond between the organic film and the adhesive is not particularly limited, and known means can be used, such as etching the organic surface with an argon cluster ion beam and time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0032] For example, when a polyimide film is used as the organic film, it is known that carboxylic acids are generated on the polyimide surface after plasma treatment. Therefore, when the silane agent has an amino group, an epoxy group, or a hydroxyl group, chemical bonds such as amide bonds, epoxy ester bonds, and ester bonds are formed between the silane agent and the polyimide, and therefore, silane agents having these functional groups are preferred. For example, a silane agent can be applied to the portion of the organic film that is to be bonded with the adhesive, and then heated, thereby bonding the organic film and the silane agent.

[0033] The organic film may also contain a silane agent. For example, when a silane agent is added in advance to a resin used for the organic film, a silane agent having a functional group capable of reacting with a functional group in the resin may be used. The leaving group of the silanol group is not particularly limited as long as it is hydrolyzable by water, and examples thereof include a methoxy group and an ethoxy group.

[0034] Taking these into consideration, the silane agent is selected from the group consisting of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-( At least one silane coupling agent selected from the group consisting of 1,3-dimethyl-butylidene)-propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, and the like can be used.

[0035] The silane agent preferably contains at least one selected from the group consisting of an aminosilane agent and an epoxysilane agent, and more preferably contains an aminosilane agent, which makes it easier to maintain adhesion when immersed in an organic ink.

[0036] The aminosilane agent is preferably at least one selected from the group consisting of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)-propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride. Commercially available aminosilane agents may be used, for example, VM-652 (manufactured by HD Microsystems, Inc.).

[0037] Examples of epoxy silane agents include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropyltriethoxysilane. Commercially available epoxy silane agents may be used, and examples thereof include AP3000 (DuPont), KBM-402 (Shin-Etsu Chemical Co., Ltd.), and KBE-403 (Shin-Etsu Chemical Co., Ltd.).

[0038] <About adhesives> The adhesive may be any adhesive capable of bonding the organic film and the adhesive via a siloxane bond. The bonding means is not particularly limited. When the surface of the organic film is treated with a silane agent, an adhesive that forms a siloxane bond with the silane agent may be used. Alternatively, an adhesive having a siloxane bond in its structure may be used and bonded to the organic film, thereby bonding the organic film and the adhesive via a siloxane bond. Alternatively, a functional group may be formed on the surface of the organic film, and an adhesive having a siloxane bond may be bonded to the functional group. The organic film and the adhesive may be bonded via a silane agent that is capable of bonding to the organic film and the adhesive and has a siloxane bond.

[0039] From the viewpoint of water repellency, the adhesive preferably has a lower oxygen atom ratio. Examples of adhesives include at least one selected from the group consisting of silsesquioxane derivatives, divinylsiloxane-bisbenzocyclobutene, dimethylpolysiloxane, tetramethylcyclotetrasiloxane, etc. These may be used alone or in combination of two or more.

[0040] The adhesive preferably contains a resin containing a cyclobutene skeleton. The adhesive more preferably contains divinylsiloxane-bisbenzocyclobutene. When divinylsiloxane-bisbenzocyclobutene is used, a silane-treated organic film and a substrate are bonded via the adhesive, and then the silane agent and the adhesive are reacted to form a bond containing a siloxane bond. For example, the reaction between the silane agent and the adhesive can be accelerated by heating. Another preferred adhesive having a siloxane bond Si—O—Si in its structure is YL9028 (Mitsubishi Chemical Corporation).

[0041] <Substrate> The substrate is not particularly limited as long as it has adhesive reliability with the adhesive, and examples thereof include a silicon wafer and a substrate in which a film made of at least one material selected from the group consisting of SiC, SiN, and SiO is formed on a silicon wafer. The aforementioned organic film may also be used as the adherend.

[0042] <Method of manufacturing liquid ejection head> An example of a method for manufacturing a liquid ejection head will be described below. The following description will mainly focus on an example of forming a flow path member and an organic film. In the following example of a method for manufacturing a liquid ejection head, the substrate to which the organic film is adhered with an adhesive is the second substrate 21. First, a first substrate 11 is prepared. Then, as shown in Fig. 3A, recesses 12 and first flow paths 13 through which a fluid flows are formed in the first substrate 11. The protrusions 12 and the like may be formed by any known means, such as deep silicon dry etching. The surface of the first substrate 11 may be treated with a silane coupling agent, which can improve the adhesion between the first substrate and the organic film.

[0043] Next, an organic film is formed on the prepared first substrate 11. For example, an attachment member having a polyamic acid film formed thereon is obtained, and the polyamic acid film is transferred to the first substrate and heated to form a polyimide film, which is an organic film. As shown in FIG. 3B, a solution containing polyamic acid is applied to a PET film, which is an attachment member 14. Thereafter, the attachment member 14 is heated, for example, at 120 to 250°C, preferably 130 to 200°C, for preferably 5 to 30 minutes, thereby forming a polyamic acid film 15.

[0044] Next, as shown in FIG. 3C, the polyamic acid film 15 is transferred and attached to the first substrate 11 so as to cover the recess 12 and the first flow path 13. Then, as shown in FIG. 3D, the polyamic acid film 15 attached to the first substrate 11 is baked for imidization while being supported by a support member 16. For example, a silicon substrate can be used as the support member 16. The means for baking for imidization is not particularly limited. The temperature is preferably 300 to 400°C, more preferably 320 to 380°C. The time is, for example, 10 to 300 minutes, preferably 30 to 200 minutes. The heat treatment causes the polyamic acid film 15 to react into a polyimide film 25.

[0045] Next, as shown in Fig. 3E, the support member 16 is removed. For example, it can be removed by etching after being thinned by grinding. This leaves a flow path member having a polyimide film 25 as a damper film arranged to cover the recess 12 and the first flow path 13.

[0046] Next, the surface of the organic film to be bonded to the adhesive is plasma treated. The outer surface of the polyimide film 25 in FIG. 3E is plasma treated. Specifically, the portion that will come into contact with the adhesive is plasma treated. This generates functional groups on the surface of the organic film, making it easier to react with the silane agent. For example, the plasma treatment can be a hydrophilic treatment using oxygen plasma irradiation using active oxygen.

[0047] Next, the plasma-treated surface of the organic film is treated with a silane agent. This process allows for the formation of bonds between the silane agent and the organic film. For example, a silane agent layer is formed on the plasma-treated surface of the organic film. As shown in FIG. 3F, the silane agent is applied to the polyimide film 25 by a known application method such as spin coating to form a silane agent layer 26. Further, heating may be performed at, for example, 70 to 120°C for 30 to 300 seconds. This promotes the reaction between the functional groups on the surface of the polyimide film 26 and the silane agent.

[0048] Next, a flow path is formed in the organic film. If necessary, a photoresist layer may be provided to protect areas other than the flow path. As shown in FIG. 3G, a positive photoresist 33 serving as an etching mask is formed on the silane agent layer 26 to prevent the polyimide film 25 and silane agent layer 26 formed in areas other than the first flow path 13 from being removed. Then, as shown in FIG. 3H, the photoresist 33 formed on the first flow path 13 is removed by photolithography. Furthermore, as shown in FIG. 3I, the polyimide film 25 and silane agent layer 26 on the first flow path 13 are removed by chemical dry etching, thereby connecting the flow path to the organic film.

[0049] Next, to form the second flow path 23 in Fig. 1, the first substrate 11 and the second substrate 21 are bonded together. That is, the organic film on the first substrate 11 is bonded to the second substrate 21 via an adhesive. Specifically, the organic film is bonded to the second substrate 21 with an adhesive, and the organic film and the adhesive are bonded together via a siloxane bond. The method for forming the bond via a siloxane bond is as described above.

[0050] The above has described an example of a method for manufacturing a liquid ejection head. The method for manufacturing a liquid ejection head preferably includes a step of plasma-treating the surface of the organic film to be bonded to the adhesive, a step of treating the plasma-treated surface of the organic film with a silane agent, and a step of bonding the organic film and the substrate with the adhesive, thereby bonding the organic film and the adhesive via siloxane bonds. [Example]

[0051] Examples and comparative examples are shown below, but the present disclosure is not limited thereto.

[0052] <Example of liquid ejection head manufacturing> An example of forming a flow path member and an organic film in relation to the manufacture of a liquid ejection head will be described below. 3A to 3I are cross-sectional views showing a manufacturing method of the flow path member of the first embodiment. First, as shown in Fig. 3A, a first substrate 11 was prepared for forming recesses 12 and first flow paths 13 through which a fluid flows. Single crystal silicon having dimensions of 200 mmφ and a thickness of 500 µm was used for the first substrate 11.

[0053] To improve the adhesion between the first substrate 11 and the polyamic acid film 15 described below, a silane coupling agent VM-652 (manufactured by HD Microsystems, Inc.) was applied to the surface of the first substrate 11 at 2000 rpm for 30 seconds. Then, the substrate was heated on a hot plate at 90°C for 90 seconds to form a silane agent layer on the surface of the first substrate 11. Thereafter, silicon deep dry etching was performed to form recesses 12 and first flow channels 13 each having a rectangular planar shape and a width of 600 μm in the short direction (FIG. 3A).

[0054] 3B, a polyamic acid solution PI2610 (HD Microsystems, Inc.) was applied by spin coating (conditions: 2500 rpm, 30 seconds) onto a 100 μm-thick PET film serving as the attachment member 14. Then, the film was baked in a clean oven at 150° C. for 15 minutes to form a polyamic acid film 15 with a thickness of 5 μm.

[0055] Next, as shown in Fig. 3C, a polyamic acid film 15 was attached to the first substrate 11 so as to cover the recess 12 and the first flow path 13. The polyamic acid film 15 was attached using a roller method capable of applying pressure and heat. Next, the attachment member 14 was peeled off from the attached polyamic acid film 15 while being bent.

[0056] Next, as shown in FIG. 3D, the polyamic acid film 15 attached to the first substrate 11 was baked for imidization while being supported by a support member 16. A silicon substrate was used as the support member 16. The imidization bake was performed at 350° C. for 1 hour in a nitrogen atmosphere. The heat treatment caused the polyamic acid film 15 to react with the polyimide film 25.

[0057] 3E, the support member 16 was thinned by grinding and then removed by etching, thereby forming a flow path member having a polyimide film 25 as a damper film arranged to cover the recess 12 and the first flow path 13.

[0058] Next, the outer surface of the polyimide film 25 was treated with a plasma device MAS8220AT (Canon The plasma treatment was carried out using a plasma treatment device manufactured by Co., Ltd. under the following conditions. (Conditions) 16℃, 0W, 90s

[0059] 3F, a silane agent VM-652 (manufactured by HD Microsystems, Inc.) was applied onto polyimide film 25 by spin coating at 2000 rpm for 30 seconds to form silane agent layer 26. Further, the film was heated on a hot plate at 90°C for 90 seconds to promote the reaction between the functional groups on the surface of polyimide film 26 and the silane agent.

[0060] Next, as shown in FIG. 3G, in order to prevent the polyimide film 25 and the silane agent layer 26 formed other than on the first flow path 13 from being removed, a positive photoresist 33 serving as an etching mask was formed on the silane agent layer 26.

[0061] Next, as shown in FIG. 3H, the photoresist 33 formed on the first flow channel 13 was removed by photolithography.

[0062] Next, as shown in Figure 3I, the polyimide film 25 and the silane agent layer 26 on the first flow path 13 were removed by chemical dry etching. A mixed gas of O2 gas and CF4 gas was used as the etching gas. After the dry etching, the etching mask was removed by oxygen ashing.

[0063] Finally, the first substrate 11 and the second substrate 21 for forming the second flow path 23 (FIG. 1) communicating with the polyimide film were bonded together using an adhesive, divinylsiloxane-bisbenzocyclobutene (CYCLOTENE 3022-47, manufactured by The Dow Chemical Company, hereinafter referred to as BCB adhesive).

[0064] Example 1 <2. Preparation of evaluation samples> Below, an adhesion sample was prepared by bonding a substrate, adhesive, and organic film together to evaluate adhesion. The adhesion was evaluated by evaluating the die shear between the organic film and adhesive before and after immersion in ink (Figure 2).

[0065] <2-1 Preparation of organic films used for evaluation samples> A support having an organic film formed thereon and used in this study was fabricated by the steps shown in FIGS. 3A to 3I. First, a support made of single-crystal silicon was prepared. A silane coupling agent, VM-652 (manufactured by HD Microsystems, Inc.), was applied to the surface of the support to which the polyamic acid film was to be attached at 2000 rpm for 30 seconds. This improves the adhesion between the support and the polyamic acid film. The silane coupling agent was baked by heating on a hot plate at 90°C for 90 seconds.

[0066] Next, a polyamic acid solution PI2610 (HD Microsystems, Inc.) was applied onto the silane coupling agent by spin coating (conditions: 2500 rpm, 30 seconds) to form a polyamic acid film, which was then baked in a clean oven at 150°C for 15 minutes. Here, polyamic acid (polyamide acid) is a precursor of polyimide, and can be obtained, for example, by reacting an aromatic diamine with a tetracarboxylic dianhydride in an organic solvent such as N-methylpyrrolidone.

[0067] Next, the polyamic acid film attached to the support was heated in a clean oven at 340°C for 2 hours to react with the film to form a polyimide film. Finally, the polyimide film on the support having the polyimide film as the outermost surface was subjected to plasma treatment using a plasma device MAS8220AT (manufactured by Canon Inc.) under the following conditions to obtain an organic film-coated support. (Conditions) 16℃, 0W, 90s

[0068] <2-2 Application of silane agent> A silane agent VM-652 (manufactured by HD Microsystems, Inc.) was applied to the organic film-coated support prepared in 2-1 by spin coating at 2000 rpm for 30 seconds, followed by heating on a hot plate at 90°C for 90 seconds to promote the reaction between the functional groups on the surface of the organic film-coated support and the silane agent. Since the bond formed between the organic film and the silane agent differs depending on the example, the bonds formed in Examples 1 to 16 are summarized in Table 4 below.

[0069] <2-3 Preparation of adhesive body> On the other hand, a solvent-diluted BCB adhesive was applied to a release film using a spin coater at 2500 rpm for 30 seconds, and then the release film coated with the BCB adhesive was heated in an oven at 100°C.

[0070] Next, a silicon chip (a Si substrate with a SiC film) was prepared, with the surface coated with HIMAL HL-1200CH (Showa Denko Materials Co., Ltd.), a polyether amide. This silicon chip coated with HIMAL served as the substrate to which the organic film was adhered using the BCB adhesive. The silicon chip was diced and pressed onto the BCB adhesive on a release film coated with BCB on a hot plate heated to 100°C, applying the BCB adhesive to the surface of the silicon chip (substrate). The reason for this is that the BCB adhesive is in a hardened state at room temperature, but when heated to 100°C, it becomes fluid and can be applied to the surface of the silicon chip. The BCB adhesive on the surface of the silicon chip was then allowed to solidify by leaving it at room temperature for 3 minutes.

[0071] Furthermore, the organic film-coated support coated with the silane agent prepared in 2-2 was heated to 100°C, and the silicon chip coated with the BCB adhesive described above was pressed against it. This caused the BCB adhesive to temporarily flow between the silicon chip (substrate) and support, filling the gap between the chip and support. The BCB adhesive was then allowed to harden by leaving it at room temperature for one hour. After curing, the evaluation sample was heated at 250°C for 1 hour to promote the reaction between the BCB adhesive and the silane agent, resulting in an adhesive bonded to the substrate, adhesive, and organic film. This generated silanol groups, which reacted with the silane agent to form covalent bonds, including siloxane bonds, between the silane coupling agent and the BCB adhesive. Because a covalent bond was formed between the organic film and the silane agent, as shown in Table 4, the organic film and adhesive were bonded via siloxane bonds.

[0072] <2-4 rating> Immediately after obtaining the bonded body, the adhesion between the polyimide and BCB adhesive was evaluated using the die shear strength measurement method shown in Figure 2. First, an organic film-coated support was prepared with a silicon chip as the substrate. Then, as shown in Figure 2, the silicon chip was pressed in the direction of arrow 201 using tool 200. The pressing force was gradually increased, and the value of the pressing force when the pattern peeled off was measured to evaluate adhesion. The value of the pressing force when the pattern peeled off is called the "die shear strength," and a higher value indicates greater adhesion between the polyimide and the BCB adhesive. More specifically, the measurements were performed using a bond tester DAGE 4000Plus (manufactured by Nordson Advanced Technologies Co., Ltd.) under the following conditions. Tool movement speed: 0.5 mm / s

[0073] Next, the organic film-coated support with the silicon chip substrate was immersed in the water-based ink and removed again after 30 days. After removal, adhesion was measured using the same procedure as after baking. The composition of the water-based ink is shown in Table 1-1 below. Table 1-2 shows the composition of the organic ink, which will be described later.

[0074] [Table 1-1]

[0075] [Table 1-2]

[0076] Example 2 The conditions were the same as in Example 1, except that the ink used in the evaluation was changed to an organic ink.

[0077] Example 3 The conditions were the same as in Example 1, except that YL9028 (Mitsubishi Chemical Corporation) was used as the adhesive instead of BCB adhesive. Although the details of the structure of YL9028 are not disclosed, it is disclosed that it has a siloxane bond Si—O—Si in its structure.

[0078] Example 4 The conditions were the same as in Example 3, except that the ink used in the evaluation was changed to an organic ink.

[0079] Example 5 The conditions were the same as in Example 1, except that an epoxy silane agent, AP3000 (DuPont), was used instead of VM652 as the silane agent.

[0080] Example 6 The conditions were the same as in Example 5, except that the ink used in the evaluation was changed to an organic ink.

[0081] Example 7 The conditions were the same as in Example 5, except that YL9028 (Mitsubishi Chemical Corporation) was used as the adhesive instead of the BCB adhesive.

[0082] Example 8 The conditions were the same as in Example 7, except that the ink used in the evaluation was changed to an organic ink.

[0083] Example 9 The conditions were the same as in Example 1, except that a photosensitive epoxy resin (composition: Table 2) was used instead of the polyamic acid solution PI2610 used in the organic film.

[0084] [Table 2]

[0085] Example 10 The conditions were the same as in Example 9, except that the ink used in the evaluation was changed to an organic ink.

[0086] Example 11 The conditions were the same as in Example 9, except that YL9028 (Mitsubishi Chemical Corporation) was used as the adhesive.

[0087] Example 12 The conditions were the same as in Example 11, except that the ink used in the evaluation was changed to an organic ink.

[0088] Example 13 The conditions were the same as in Example 9, except that the epoxy silane agent AP3000 was used instead of VM652 as the silane agent.

[0089] Example 14 The conditions were the same as in Example 13, except that the ink used in the evaluation was changed to an organic ink.

[0090] Example 15 The conditions were the same as in Example 13, except that YL9028 (Mitsubishi Chemical Corporation) was used as the adhesive.

[0091] Example 16 The conditions were the same as in Example 15, except that the ink used in the evaluation was changed to an organic ink.

[0092] Comparative Example 1 The conditions were the same as in Example 1, except that a urethane adhesive, KU550 (Konishi Co., Ltd.), was used as the adhesive.

[0093] Comparative Example 2 The conditions were the same as those in Comparative Example 1, except that the ink used in the evaluation was changed to an organic ink.

[0094] Comparative Example 3 The conditions were the same as in Example 1, except that no silane agent was used.

[0095] Comparative Example 4 The conditions were the same as those in Comparative Example 3, except that the ink used in the evaluation was changed to an organic ink. The above levels are summarized in Table 3.

[0096] [Table 3]

[0097] (Evaluation results) The evaluation results are shown below. In this study, the initial die shear strength (initial adhesion) was set at 10 kgf or more, based on the fact that the initial die shear strength was 9.9 kgf when the workpiece was produced without any silane treatment, following the prior art. Furthermore, the adhesion of the die shear strength after ink immersion was ranked A, B, C, or D according to the degree of decrease from the initial state. These criteria can be summarized as follows: <Initial adhesion> A: Initial adhesion of 10 kgf or more B: Initial adhesion less than 10 kgf <Adhesion after ink immersion> A: Adhesion after 30 days of ink immersion is 95% or more of the initial adhesion B: Adhesion after 30 days of ink immersion is 85% to 95% of the initial adhesion C: Adhesion after 30 days of ink immersion is 75% or more but less than 85% of the initial adhesion D: Adhesion after 30 days of ink immersion is less than 75% of the initial adhesion

[0098] (Type of organic film) First, in the examples, whether the organic film was made of polyimide or photosensitive epoxy, an initial adhesion of 10 kgf or more was obtained, and even after immersion in ink, the die shear strength maintained 75% or more of the initial value. However, when comparing Example 2 and Example 10, the results suggest that when organic ink is used, the use of polyimide for the organic film has a higher ink adhesion retention ability than the use of photosensitive epoxy. This is thought to be because the epoxy group has higher hydrophilicity and lipophilicity than imide compounds, and therefore has a higher affinity for the solvent in the ink, making it more susceptible to swelling.

[0099] (Type of silane agent) Furthermore, in the examples, whether the silane agent was an aminosilane or an epoxysilane agent, an initial adhesion of 10 kgf or more was obtained, and even after immersion in ink, the die shear strength remained at 75% or more of the initial value. Furthermore, by comparing these with Comparative Examples 3 and 4, which did not use a silane agent, it was confirmed that the silane agent was effective in improving adhesion. This is believed to be because the silane agent bonds the organic film and adhesive via siloxane bonds, strengthening the bond between the organic film and adhesive.

[0100] In addition, in the cases of Comparative Examples 3 and 4, even without using a silane agent, an ester bond is formed between the carboxyl groups on the organic film surface and the hydroxyl groups of the adhesive, but the siloxane bonds formed in the examples are more water- and oil-repellent, and therefore are thought to have resulted in higher ink durability.

[0101] (Bonding of organic film and silane agent) The bonds formed in the combination of organic film and silane agent used in this example are shown in Table 4.

[0102] [Table 4]

[0103] Although the presence of a siloxane bond between the organic film and the adhesive can improve adhesion, the results in Table 4 suggest that adhesion is further improved when there is a bond represented by the following general formula between the organic film and the silane agent: In other words, as mentioned above, it is preferable to have a bond represented by formula (1) in addition to a siloxane bond between the organic film and the adhesive. [General bond formula between organic film and silane agent] R1-CO-NH-R2, R1-CH2-CHOH-CH2-O-CO-CH2-CH2-R2, R1-CHOH-CH2-N-R2, R1-CH2-(CH2-O-CH2)n-CH2-R2 R1 and R2 represent bonding sites with the organic film and the silane agent, for example, carbon atoms at the ends of the organic film and the silane agent. Also, n is the average number of moles added, and represents an integer of, for example, 1 to 200, preferably 10 to 200.

[0104] (Type of adhesive) When BCB adhesive or YL9028, which has silanol groups, was used as the adhesive, initial adhesion of 10 kgf or more was achieved regardless of the type of organic film or silane agent, and die shear strength of 75% or more of the initial value was maintained even after ink immersion. On the other hand, when the urethane adhesive KU-550 was used as the adhesive, adhesion decreased significantly, and 75% of the initial die shear strength was not achieved after ink immersion. This suggests that the formation of siloxane bonds, which combine strong covalent bonds and water repellency, between the adhesive and the organic film is an essential requirement for improving adhesion.

[0105] Furthermore, when comparing BCB adhesive with YL9028, for example, when comparing Examples 2 and 4, the BCB adhesive was shown to have slightly better adhesion and ink resistance. This is thought to be because the epoxy group has higher hydrophilicity and lipophilicity than imide compounds, which means it has a higher affinity for the solvent in the ink and is more likely to swell.

[0106] The present disclosure relates to the following configurations. (Configuration 1) A liquid ejection head, The liquid ejection head includes: a discharge port for discharging a liquid; a pressure chamber in which pressure acts on the liquid discharged from the discharge port; a flow path communicating with the pressure chamber; a substrate on which the flow channel is formed; an organic film that constitutes a part of a wall surface of the flow channel and that suppresses vibration of the liquid in the flow channel; the organic film is adhered to the substrate with an adhesive; The liquid ejection head is characterized in that the organic film and the adhesive are bonded via a siloxane bond. (Configuration 2) The liquid ejection head according to configuration 1, wherein the liquid ejection head contains a bond represented by the following formula (1) in addition to the siloxane bond between the organic film and the adhesive. ―C1-X-C2― ···(1) Here, in (1), X is -CO-NH-, -CH2-CHOH-CH2-O-CO-CH2-CH2-, -CHOH-CH2-N-, -CH2-(CH2-O-CH2)n-CH2-, at least one selected from the group consisting of —CO—O—, —CO—S—, —O—, and —NH—CO—O—; n is the average number of moles added and represents an integer of 1 to 200; C1 and C2 are each independently a carbon atom. (Configuration 3) 3. The liquid ejection head according to claim 1, wherein the organic film contains polyimide. (Configuration 4) 4. The liquid ejection head according to any one of configurations 1 to 3, wherein the portion of the organic film that is in contact with the adhesive is plasma treated. (Configuration 5) the adhesion between the organic film and the adhesive includes bonding via a silane agent; 5. The liquid ejection head according to any one of configurations 1 to 4, wherein the silane agent includes an aminosilane agent. (Configuration 6) 6. The liquid ejection head according to any one of configurations 1 to 5, wherein the adhesive contains a resin containing a cyclobutene skeleton. (Configuration 7) 7. The liquid ejection head according to any one of configurations 1 to 6, wherein the adhesive contains divinylsiloxane-bisbenzocyclobutene. (Configuration 8) the liquid ejection head includes an ejection element that generates pressure; 8. The liquid ejection head according to any one of configurations 1 to 7, wherein the ejection element is a piezoelectric element. [Explanation of symbols]

[0107] 10 flow path member, 11 first substrate, 12 recess, 13 first flow path, 14 attachment member, 15 polyamic acid film, 16 support member, 21 second substrate, 23 Second flow path, 25 polyimide film (flexible member), 26 silane agent layer, 33 photoresist, 35: air communication hole

Claims

1. A liquid ejection head, The liquid ejection head includes: a discharge port for discharging a liquid; a pressure chamber in which pressure acts on the liquid discharged from the discharge port; a flow path communicating with the pressure chamber; a substrate on which the flow channel is formed; an organic film that constitutes a part of a wall surface of the flow channel and that suppresses vibration of the liquid in the flow channel; the organic film is adhered to the substrate with an adhesive; The liquid ejection head is characterized in that the organic film and the adhesive are bonded via a siloxane bond.

2. 2. The liquid ejection head according to claim 1, wherein the liquid ejection head contains a bond represented by the following formula (1) in addition to the siloxane bond between the organic film and the adhesive: -C1-X-C2- ...(1) Here, in (1), X is —CO—NH—, -CH ２ -CHOH-CH ２ -O-CO-CH ２ -CH ２ -、 -CHOH-CH ２ -N-、 -CH ２ -(CH ２ -O-CH ２ )n-CH ２ -、 at least one selected from the group consisting of —CO—O—, —CO—S—, —O—, and —NH—CO—O—; n is the average number of moles added and represents an integer of 1 to 200; C1 and C2 are each independently a carbon atom.

3. The liquid ejection head according to claim 1 , wherein the organic film contains polyimide.

4. 3. The liquid ejection head according to claim 1, wherein the portion of the organic film that is in contact with the adhesive is plasma-treated.

5. the adhesion between the organic film and the adhesive includes bonding via a silane agent; The liquid ejection head according to claim 1 , wherein the silane agent includes an aminosilane agent.

6. The liquid ejection head according to claim 1 or 2, wherein the adhesive contains a resin containing a cyclobutene skeleton.

7. 3. The liquid ejection head according to claim 1, wherein the adhesive contains divinylsiloxane-bisbenzocyclobutene.

8. the liquid ejection head includes an ejection element that generates pressure; 3. The liquid ejection head according to claim 1, wherein the ejection element is a piezoelectric element.

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