Liquid ejection head and double liquid mixing type adhesive

Abstract

The present application relates to liquid ejection head and double liquid mixed type adhesive, provide a kind of liquid ejection head, with little environmental load, effect temperature is low, the adhesive of excellent liquid resistance Cured product. Liquid ejection head has the cured product of double liquid mixed type adhesive, double liquid mixed type adhesive includes A liquid and B liquid, the A liquid includes main agent containing epoxy resin and 3,4-dihydrocoumarin, the B liquid includes the polymer of aromatic amine, alkyl phenol and bis (aminomethyl) norbornane, alkyl phenol is (a) at least having one ethyl alkyl phenol;Or (b) alkyl's carbon atom number is 1~3, and at least respectively has one methyl and one isopropyl alkyl phenol, the ratio of the ester equivalent of 3,4-dihydrocoumarin relative to the phenol equivalent of alkyl phenol is 4.0 above and 12.0 below.

Description

Technical Field

[0001] This disclosure relates to liquid jetting heads and two-component mixed adhesives. Background Technology

[0002] Conventionally, resin materials have been used in the manufacture of liquid ejection heads. For example, in Patent Document 1, a sealant made of resin material was used to seal the electrical connection between a recording element substrate and an electrical wiring component. The recording element substrate includes an ejection energy generating element for ejecting liquid, and the electrical wiring component is used to send signals to the recording element substrate. Patent Document 1 describes that bisphenol-type epoxy resin can be used as the main agent and an aliphatic amine can be used as the curing agent. It should be noted that while Patent Document 1 shows a specific example of using a resin material as a sealant, the application of such a resin material is not limited to sealants; for example, it can also be used as an adhesive.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-35809

[0004] Furthermore, the adhesive used in the liquid jet head is required to have excellent resistance to liquids such as acids, and the adhesive applied to bond the components constituting the liquid jet head to each other must cure at low temperatures.

[0005] However, in existing epoxy adhesives, the use of highly reactive bisphenol-type epoxy resins as the main agent and highly reactive aliphatic amines as curing agents results in insufficient liquid resistance despite low-temperature curing. Furthermore, from an environmental impact perspective, the use of bisphenol is not preferred.

[0006] As described above, it is desirable to have excellent liquid resistance while reducing environmental impact, and to use an adhesive that cures at low temperatures to bond the components constituting the liquid jet head together. Of course, the same technical problems exist for components other than the liquid jet head that also require the same requirements. Summary of the Invention

[0007] According to one aspect of this disclosure, a liquid injection head for spraying liquid from a nozzle is provided. The liquid injection head is characterized by comprising a first component, a second component, and a cured product of a two-component mixed adhesive bonding the first component and the second component, the two-component mixed adhesive comprising: a liquid A containing a main agent comprising a bisphenol-free epoxy resin and 3,4-dihydrocoumarin; and a liquid B containing at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, a polymer of an aromatic amine, and an alkylphenol, wherein the alkylphenol is: (a) an alkylphenol having at least one ethyl group; or (b) an alkylphenol having 1 to 3 carbon atoms and having at least one methyl group and one isopropyl group, wherein the ratio of the ester equivalent of the 3,4-dihydrocoumarin to the phenol equivalent of the alkylphenol is 4.0 or more and 12.0 or less. Attached Figure Description

[0008] Figure 1 This is a schematic diagram showing the general structure of the liquid injection device in the embodiment.

[0009] Figure 2 This is a 3D view of the nozzle module.

[0010] Figure 3 This is an exploded 3D view of the liquid jet nozzle.

[0011] Figure 4 yes Figure 3 Sectional view of line IV-IV.

[0012] Figure 5 This is a cross-sectional view of the injection unit.

[0013] Figure 6 It is a diagram that shows a list of the components used in the experiment.

[0014] Figure 7 This is a diagram representing chemical formulas (f1) and (f2).

[0015] Figure 8 This is a diagram used to illustrate the evaluation method.

[0016] Figure 9 This is a graph showing the equivalent ratio and mass ratio of Experimental Examples 1 to 5.

[0017] Figure 10 This is a graph showing the equivalent ratio and mass ratio of Experimental Examples 6 to 12.

[0018] Figure 11 This is a graph showing the equivalent ratio and mass ratio of Experimental Examples 13 to 16.

[0019] Figure 12 This is a graph summarizing the evaluation results of Experiments 1 through 12.

[0020] Figure 13 This is a graph summarizing the evaluation results of Experiments 13 to 16.

[0021] Explanation of reference numerals in the attached figures

[0022] C: Pressure chamber; GL: Solidified material; N: Nozzle; Ra: Space; Rb: Space; S1a: First supply flow path of laminate; S1b: Second supply flow path of laminate; S2a: First discharge flow path of laminate; S2b: Second discharge flow path of laminate; Sn: Flow path of structure; Su: Flow path component; 3: Nozzle module; 12: Medium; 14: Liquid container; 15: Sub-tank; 16: Conveying mechanism; 20: Nozzle moving mechanism; 21: Conveyor belt; 22: Bracket; 26: Spraying unit; 26a 26b: Supply liquid chamber; 26c: Supply flow path; 30: Connecting flow path; 31: Liquid injection head; 32: Cover component; 32: Support component; 32a: First opening; 32b: Second opening; 32c: Third opening; 32d: Partition; 33: Flow path structure; 34: Pressure chamber base plate; 34a: Opening; 36: Fixing plate; 37: Reinforcing plate; 44: Piezoelectric element; 46: Sealing body; 46a: Sealing body opening; 48: Basket part; 48a: Through hole; 51a: Flexible base 53: Flow path substrate; 54: Vibrating plate; 62: Nozzle plate; 64: Flow path sealing component; 80: Control unit; 100: Liquid injection device; 301: Support body; 302: Mounting hole; 311: Hole for first connection part; 312: Hole for second connection part; 313: First hole; 321: Receiving part; 322: First through hole of bracket; 323: Second through hole of bracket; 324: Flange; 331a: Upper connection part for first supply; 331b: Upper connection part for second supply; 332a 332b: Upper connecting part for first discharge; 333: Upper connecting part for second discharge; 336a: First supply pipe for housing; 336b: Second supply pipe for housing; 337a: First discharge pipe for housing; 337b: Second discharge pipe for housing; 342a: Lower connecting part for first discharge; 342b: Lower connecting part for second discharge; 361: Opening; 371: Opening; 381: Wiring substrate; 382: Wiring component; 383v: Second circuit board; 383u: First circuit board. Detailed Implementation

[0023] A. Implementation method: A1. Overall structure of the liquid injection device: Figure 1This is a schematic diagram showing the general structure of the liquid jetting device 100 in the embodiment. The liquid jetting device 100 is an inkjet printing device that prints by jetting droplets of liquid ink onto a medium 12. The medium 12 can be any material, such as printing paper, resin film, or cloth. In the following description, the X, Y, and Z directions, which are mutually orthogonal, are used. Furthermore, when the orientation is determined, positive directions are represented as "+", and negative directions as "-", and positive and negative signs are used in the direction description. In this embodiment, the X direction is the main scanning direction, which is the direction of movement of the liquid jetting head 30. The Y direction is the secondary scanning direction, which is the medium transport direction orthogonal to the main scanning direction. The -Z direction is the ink jetting direction. In the following description, the +Z direction is sometimes referred to as "up" and the -Z direction as "down".

[0024] The liquid injection device 100 includes: a nozzle module 3; a nozzle moving mechanism 20; multiple liquid receiving sections 14; multiple auxiliary tanks 15; a conveying mechanism 16; and a control unit 80. The nozzle module 3 has multiple liquid injection heads 30.

[0025] Each liquid container 14 contains the ink supplied to the printhead module 3. As the liquid container 14, it can be a bag-shaped liquid pack formed of a flexible film, an ink canister that can be replenished, or a removable ink cartridge, etc.

[0026] As inks, water-based pigment inks, solvent-based inks, and UV-curable inks can be used. UV-curable inks are also known as UV inks. Additionally, when using fabric as the medium 12, acidic pretreatment inks containing organic acids such as citric acid, malic acid, and malonic acid are sometimes used. When this pretreatment ink is sprayed onto the fabric, it reacts with the ink of the coloring material that is subsequently sprayed, specifically causing the dyes and pigments used as coloring materials to agglomerate. Therefore, the pretreatment ink has the effect of inhibiting the penetration of the coloring material ink and inhibiting the bleeding of the coloring material.

[0027] Each auxiliary tank 15 is connected to the liquid container 14 via an ink flow pipe. Furthermore, each auxiliary tank 15 is connected to the printhead module 3 via a first pipe for supplying ink to the printhead module 3 and a second pipe for returning ink from the liquid jet head 30 to the auxiliary tank 15. Ink is supplied from the liquid container 14 to each auxiliary tank 15, and ink returns from the printhead module 3. The ink then circulates between the auxiliary tanks 15 and the printhead module 3.

[0028] In the following description, we will use the case where the liquid injection device 100 has two liquid receiving sections 14 and two auxiliary tanks 15 as an example. In this embodiment, the two liquid receiving sections 14 each contain inks of different colors. To distinguish between the two inks, the ink contained in one liquid receiving section 14 is referred to as the first ink, and the ink contained in the other liquid receiving section 14 is referred to as the second ink. It should be noted that the liquid injection device 100 may have one liquid receiving section 14 or more. In addition, the inks contained in the two liquid receiving sections 14 may also be inks of the same color.

[0029] The printhead module 3 has a plurality of nozzles N for ejecting ink, described later. The printhead module 3 ejects ink supplied from the liquid reservoir 14 from the plurality of nozzles N onto the medium 12.

[0030] The nozzle moving mechanism 20 includes a conveyor belt 21 and a bracket 22 for accommodating the nozzle module 3. The bracket 22 is connected to the conveyor belt 21 and reciprocates in the X direction as the conveyor belt 21 is driven. The conveying mechanism 16 conveys the medium 12 in the +Y direction.

[0031] The control unit 80 includes one or more processing circuits such as a CPU (Central Processing Unit) and an FPGA (Field Programmable Gate Array), and storage circuits such as semiconductor memory, controlling the overall operation of the liquid jetting device 100. The control unit 80 is electrically connected to the conveying mechanism 16, the nozzle moving mechanism 20, and the liquid jetting head 30, controlling each component. By jetting liquid from the nozzle N onto the medium 12 conveyed by the conveying mechanism 16, an image is printed on the medium 12.

[0032] Figure 2 This is a 3D view of nozzle module 3. (See diagram below.) Figure 2 As shown, the nozzle module 3 has a support body 301 and a plurality of liquid injection heads 30. In this embodiment, the nozzle module 3 has eight liquid injection heads 30. It should be noted that the number of liquid injection heads 30 in the nozzle module 3 is not limited to eight; for example, it may have only one.

[0033] The support body 301 is a plate-shaped component that supports a plurality of liquid injection heads 30. The support body 301 has a plurality of mounting holes 302. Each liquid injection head 30 is supported by the support body 301 in a state of being embedded in the mounting hole 302. The plurality of liquid injection heads 30 are arranged in a matrix.

[0034] A2. Structure of the liquid injection head: Figure 3 This is an exploded perspective view of the liquid injection head 30. Figure 4 yes Figure 3 The cross-sectional view of line IV-IV. Line IV-IV passes through the center of the first through hole 322 of the bracket, as described later. Figure 3 As shown, the liquid injection head 30 includes a cover component 31, a support component 32, a flow path structure 33, a fixing plate 36, a reinforcing plate 37, multiple injection units 26, a wiring substrate 381, a wiring component 382, ​​a first circuit board 383u, and a second circuit board 383v. In this embodiment, the liquid injection head 30 has four injection units 26.

[0035] The fixing plate 36 is a plate component used to fix the plurality of spraying units 26 relative to the support component 32. In this embodiment, the fixing plate 36 is made of stainless steel. The fixing plate 36 has a plurality of openings 361 for exposing the nozzles N formed on the lower surface of each spraying unit 26.

[0036] The reinforcing plate 37 is a plate component used to reinforce the fixing plate 36. In this embodiment, the reinforcing plate 37 is made of stainless steel. The reinforcing plate 37 is fixed to the fixing plate 36 by the cured adhesive GL, which will be described later. Similar to the fixing plate 36, the reinforcing plate 37 has a plurality of openings 371 for exposing the nozzles N formed on the lower surface of each spraying unit 26.

[0037] The injection unit 26 includes the nozzle N, the first housing supply pipe 336a, the first housing discharge pipe 337a, the second housing supply pipe 336b, and the second housing discharge pipe 337b described above. Details regarding the injection unit 26 will be described below.

[0038] The support component 32 has multiple receiving portions 321, multiple first through holes 322, and multiple second through holes 323. The support component 32 is made of a metal such as stainless steel. Each receiving portion 321 is formed to project downwards from a plate-shaped flange 324 of the support component 32. The lower side of each receiving portion 321 is open. An injection unit 26 is received in each receiving portion 321. Each first through hole 322 is a through hole for inserting any one of the housing first supply pipe 336a, housing first discharge pipe 337a, housing second supply pipe 336b, and housing second discharge pipe 337b of the injection unit 26. Each second through hole 323 is a through hole for inserting the flexible substrate 51a, described later.

[0039] The flow path structure 33 includes a stacked body 333, a first supply upper connection portion 331a, a first discharge upper connection portion 332a, a second supply upper connection portion 331b, and a second discharge upper connection portion 332b. The stacked body 333 is constructed by stacking multiple flow path components Su. Each flow path component Su defines a flow path that communicates with the nozzle and through which the liquid flows, i.e., the flow path Sn of the structure described later.

[0040] like Figure 4 As shown, the laminate 333 is constructed by bonding adjacent flow path components Su to each other using a cured adhesive GL. In this embodiment, the material of each flow path component Su is resin.

[0041] A structural flow path Sn is formed on the laminate 333 for allowing ink to flow between the sub-tank 15 and the jetting unit 26. The structural flow path Sn includes a first supply flow path S1a, a first discharge flow path S2a, a second supply flow path S1b, and a second discharge flow path S2b. The first supply flow path S1a and the first discharge flow path S2a are for allowing the first ink to flow. The second supply flow path S1b and the second discharge flow path S2b are for allowing the second ink to flow. The first supply flow path S1a and the second supply flow path S1b are for allowing ink to flow from the sub-tank 15 to the jetting unit 26. The first discharge flow path S2a and the second discharge flow path S2b are for allowing ink to flow from the jetting unit 26 to the sub-tank 15.

[0042] Each structural flow path Sn is composed of grooves formed on the upper or lower surface of each flow path component Su and through holes extending in the thickness direction of each flow path component Su. It should be noted that... Figure 4 In this context, the flow path Sn of the structure is simplified.

[0043] like Figure 3 As shown, a first supply upper connection portion 331a, a first discharge upper connection portion 332a, a second supply upper connection portion 331b, and a second discharge upper connection portion 332b are disposed on the upper surface of the laminate 333. The first supply upper connection portion 331a, the first discharge upper connection portion 332a, the second supply upper connection portion 331b, and the second discharge upper connection portion 332b are respectively connected to the first supply flow path S1a, the first discharge flow path S2a, the second supply flow path S1b, and the second discharge flow path S2b of the laminate.

[0044] Wiring substrate 381 and wiring component 382 are mounting components for electrically connecting control unit 80 and injection unit 26. Wiring and the like are formed on wiring substrate 381. Wiring component 382 is a connector for connecting to a signal cable (not shown). Electronic circuits are formed on first circuit substrate 383u and second circuit substrate 383v. First circuit substrate 383u and second circuit substrate 383v are electrically connected to wiring substrate 381.

[0045] The cover member 31 houses the laminate 333, wiring substrate 381, wiring member 382, ​​first circuit board 383u, and second circuit board 383v. Materials for the cover member 31 include, for example, resin and metal. The cover member 31 has two first connection holes 311, two second connection holes 312, and a first hole 313. The first hole 313 is for inserting the wiring member 382. A first supply upper connection 331a or a second supply upper connection 331b is inserted into each of the two first connection holes 311. A first discharge upper connection 332a or a second discharge upper connection 332b is inserted into each of the two second connection holes 312.

[0046] It should be noted that the materials of the cover component 31 and the support component 32 are not limited to the materials described above. For example, the support component 32 can also be made of resin. In addition, the materials of the cover component 31 and the support component 32 can also be, for example, carbon steel or a combination of resin and metal.

[0047] like Figure 4 As shown, the cover component 31 houses a laminate 333, a wiring component 382, ​​a first circuit board 383u, and a second circuit board 383v. The support component 32 houses the spraying unit 26. Furthermore, a fixing plate 36 and a reinforcing plate 37 are disposed on the lower side of the support component 32. The reinforcing plate 37, the fixing plate 36, and the support component 32 are bonded together by a cured adhesive GL. By bonding the fixing plate 36, which supports the spraying unit 26 from below, and the support component 32, the spraying unit 26 is fixed to the support component 32. The cover component 31, which houses the aforementioned components, and the support component 32, which houses the aforementioned components, are connected to assemble a liquid spray head 30.

[0048] The flow path structure 33 further includes a first supply lower connection portion (not shown), a first discharge lower connection portion 342a, a second supply lower connection portion (not shown), and a second discharge lower connection portion 342b (not shown). The first supply lower connection portion, the first discharge lower connection portion 342a, the second supply lower connection portion, and the second discharge lower connection portion 342b are tubes having flow paths for ink flow, protruding from the lower surface of the flow path component Su at the bottom layer of the laminate 333. The flow paths of each of the first supply lower connection portion (not shown), the first discharge lower connection portion 342a, the second supply lower connection portion (not shown), and the second discharge lower connection portion 342b are respectively connected to the first supply flow path S1a, the first discharge flow path S2a, the second supply flow path S1b, and the second discharge flow path S2b of the laminate.

[0049] like Figure 4 As shown in the magnified view, the flow path component Su of the lowest layer of the laminate 333 and the upper surface of the support component 32 are bonded together by the cured adhesive GL. Additionally, the second discharge lower connection portion 342b and the housing second discharge pipe 337b are bonded together by the cured adhesive GL. The first supply lower connection portion (not shown), the first discharge lower connection portion 342a, and the second supply lower connection portion (not shown), which are connection portions other than the second discharge lower connection portion 342b, are similarly bonded to the housing first supply pipe 336a, the housing first discharge pipe 337a, and the housing second discharge pipe 337b respectively by the cured adhesive GL.

[0050] A3. Structure of the injection unit: Figure 5 This is a cross-sectional view of the injection unit 26. (For example...) Figure 5 As shown, the spraying unit 26 includes a nozzle plate 62, two flow path sealing components 64, a flow path substrate 53, a pressure chamber substrate 34, a vibrating plate 54, a sealing body 46, a housing portion 48, and a flexible substrate 51a. The nozzle plate 62, flow path sealing components 64, flow path substrate 53, pressure chamber substrate 34, vibrating plate 54, and sealing body 46 are elongated plate-shaped components in the Y direction. Each of these components has a structure that is approximately linearly symmetrical with respect to its centerline in the X direction. The planar shape of the pressure chamber substrate 34, vibrating plate 54, and sealing body 46 is smaller than that of the flow path substrate 53 and the housing portion 48. During assembly, the nozzle plate 62, the two flow path sealing components 64, the flow path substrate 53, the pressure chamber substrate 34, the vibrating plate 54, the sealing body 46, and the housing portion 48 are stacked sequentially and bonded together by a cured adhesive GL (not shown).

[0051] Nozzle plate 62 is a plate-shaped component having a plurality of nozzles N. Each nozzle N is a through-hole with a generally circular planar shape. The plurality of nozzles N are arranged along the Y direction. There are two rows of nozzles N arranged along the X direction. Two flow path sealing components 64 are configured to clamp nozzle plate 62 in the X direction. The material of each flow path sealing component 64 is, for example, stainless steel (SUS).

[0052] The flow path substrate 53 is, for example, a silicon substrate. The flow path substrate 53 has two first openings 32a, a plurality of second openings 32b, and a plurality of third openings 32c. The planar shape of the first opening 32a is a long rectangle in the Y direction. The first opening 32a is formed along an edge parallel to the Y direction of the flow path substrate 53. The plurality of second openings 32b are arranged in the Y direction. Similarly, the plurality of third openings 32c are arranged in the Y direction. There are two columns of second openings 32b and two columns of third openings 32c. In the X direction, the first opening 32a, a column of one second opening 32b, a column of one third opening 32c, a column of one second opening 32b, and the first opening 32a are arranged sequentially. Furthermore, the second openings 32b and third openings 32c adjacent in the X direction are formed in a manner that is substantially the same in position in the Y direction.

[0053] Multiple openings 34a are formed on the pressure chamber substrate 34. The planar shape of the openings 34a is a long rectangle in the X direction. The multiple openings 34a are arranged in the Y direction. There are two rows of multiple openings 34a arranged along the X direction. It should be noted that the openings 34a are formed at positions that overlap with the second opening 32b and the third opening 32c formed adjacent to the flow path substrate 53 when viewed from the Z direction.

[0054] A piezoelectric element 44 is formed on the vibrating plate 54 at a position overlapping with the opening 34a formed on the pressure chamber substrate 34 when viewed from the Z direction. A sealing body 46 strengthens the pressure chamber substrate 34 and the vibrating plate 54, protecting the piezoelectric element 44. The sealing body 46 has a sealing body opening 46a. The planar shape of the sealing body opening 46a is a long rectangle in the Y direction.

[0055] The first circuit board 383u or the second circuit board 383v is electrically connected to the piezoelectric element 44 via the flexible substrate 51a.

[0056] The housing 48 is a shell for storing ink and has a frame shape. The material of the housing 48 is resin. In the case of stacking, a pressure chamber substrate 34, a vibrating plate 54, and a sealing body 46 are arranged in the internal space of the housing 48. Through holes 48a are formed at both ends of the housing 48 in the X direction.

[0057] A space Rb extending along the Y direction is formed at each of the two ends of the housing portion 48 in the X direction. The space Rb communicates with the through hole 48a. A space Ra, a supply liquid chamber 26a, and a supply flow path 26b are formed by connecting the flow path substrate 53 and the flow path sealing member 64. The space Ra is the internal space of the first opening 32a. The supply liquid chamber 26a is the space surrounded by the partition 32d that separates the first opening 32a and the second opening 32b and the flow path sealing member 64. The supply flow path 26b is the internal space of the second opening 32b. The space Ra communicates with the space Rb and the supply liquid chamber 26a, and the supply liquid chamber 26a communicates with the supply flow path 26b. A pressure chamber C is formed by connecting the pressure chamber substrate 34 and the vibrating plate 54. The pressure chamber C is the space surrounded by the opening 34a and the vibrating plate 54. The pressure chamber C communicates with the supply flow path 26b. A communicating flow path 26c is formed by connecting the flow path substrate 53 and the nozzle plate 62. The connecting flow path 26c is the internal space of the third opening 32c. The connecting flow path 26c is connected to the pressure chamber C and the nozzle N.

[0058] Spaces Ra and Rb function as liquid storage chambers for storing ink supplied to pressure chamber C. Space Rb communicates with multiple spaces Ra arranged in the Y direction, and ink supplied via through hole 48a is stored in multiple spaces Ra via space Rb. The ink stored in spaces Ra is supplied to pressure chamber C by flowing through supply liquid chamber 26a and supply flow path 26b.

[0059] The four through holes 48a formed in the spraying unit 26 respectively define the flow path of the first supply pipe 336a, the first discharge pipe 337a, the second supply pipe 336b, and the second discharge pipe 337b of the housing. Thus, the first ink is stored in one of the two spaces Rb formed in the spraying unit 26, and the second ink is stored in the other space Rb formed in the spraying unit 26.

[0060] In the top view viewed from the Z direction, piezoelectric elements 44 are arranged at positions overlapping each of the two pressure chambers C. A drive signal and a reference voltage are input to the piezoelectric elements 44 via the flexible substrate 51a. By inputting the drive signal and the reference voltage and applying the voltage, the piezoelectric elements 44 deform, and the vibrating plate 54 vibrates in conjunction with the deformation of the piezoelectric elements 44, causing pressure changes within the pressure chambers C, thereby ejecting ink from the nozzle N.

[0061] A4. Details of the adhesive: As described above, adhesives are used at multiple locations during the manufacture of the liquid injection head 30. In this embodiment, for example, the resin housing portion 48 and the flow path substrate 53, which serves as a silicon substrate, are bonded together using an adhesive. Additionally, the flow path substrate 53, which serves as a silicon substrate, and the stainless steel flow path sealing member 64 are bonded together using an adhesive. For example, the cured material GL liquid-tightly connects the flow path defined by the housing portion 48 (i.e., the through hole 48a) and the flow path defined by the flow path substrate 53 (i.e., the first opening 32a). The housing portion 48 is an example of a "first component," and the flow path substrate 53 is an example of a "second component."

[0062] In the bonding process between the housing portion 48 and the flow path substrate 53, after applying adhesive to at least one of the housing portion 48 and the flow path substrate 53, the adhesive is cured at a curing temperature. When the curing temperature is relatively high, especially when bonding different types of materials with large differences in thermal expansion coefficients, stress may occur between the bonded materials. For example, when the curing temperature is above 100°C, the bonded component may warp. Therefore, the curing temperature is preferably below 80°C, and more preferably below 60°C.

[0063] The coefficient of linear expansion of thermosetting resins containing fillers is 8~11×10⁻⁶. -6 The coefficient of linear expansion of thermosetting resins is approximately 15 × 10⁻⁶ K. -6 The coefficient of linear expansion of silicon is approximately 2.6 × 10⁻⁶ K. -6 The coefficient of linear expansion of stainless steel is approximately 10~18×10⁻⁶ K. -6 The coefficient of linear expansion is approximately / K. The above values ​​are for linear expansion at 293K.

[0064] Furthermore, as described above, the inks used in the liquid jetting device 100 include coloring inks containing coloring materials, pretreatment inks, and UV inks. The coloring inks contain water-soluble organic solvents such as alkyl ethers. The pretreatment inks contain organic acids and are acidic. The UV inks contain monomers. Therefore, the cured adhesive GL is required to be resistant to these various liquids. It should be noted that "resistant" means that the change in adhesive strength of the cured adhesive GL after contact with the aforementioned liquids is small relative to the initial adhesive strength of the cured adhesive GL. In the following description, resistance to alkyl ethers is referred to as ether resistance, resistance to acidic liquids is referred to as acid resistance, and resistance to monomers is referred to as monomer resistance. Furthermore, ether resistance, acid resistance, and monomer resistance are collectively referred to as liquid resistance.

[0065] Furthermore, adhesives with low environmental impact are required. For example, bisphenol A, used in the synthesis of glycidyl ether type epoxy resins commonly used as adhesives, and nonylphenol, which can be used as an adhesive accelerator, have high environmental impacts. The inventors have discovered an adhesive with low environmental impact, relatively low curing temperature, and liquid resistance.

[0066] Specifically, in this embodiment, for example, the two-component adhesive used in bonding the housing portion 48 to the flow path substrate 53 is a two-component adhesive comprising liquid A and liquid B. In the following description, unless specifically stated otherwise, the two-component adhesive having the features of this application will be simply referred to as adhesive. Furthermore, in the following description, unless specifically stated otherwise, liquid A, liquid B, and the main agent refer to liquid A, liquid B, and the main agent constituting the two-component adhesive having the features of this application.

[0067] Solution A contains a main agent, which includes a bisphenol-free epoxy resin and 3,4-dihydrocoumarin. A bisphenol-free epoxy resin refers to a resin in which bisphenol is not used in the synthesis of the epoxy resin. In this embodiment, the bisphenol-free epoxy resin is a tetrafunctional glycidylamine type epoxy resin, namely N,N,N',N'-tetraglycidyl-m-xylenediamine.

[0068] Solution B contains at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, a polymer of an aromatic amine, and an alkylphenol.

[0069] The polymer of aromatic amines includes a formaldehyde polymer comprising at least one of 2-ethylaniline and 4,4'-methylenebis(2-ethylaniline) in the repeating unit; or a formaldehyde polymer comprising at least one of 2-ethyl-6-methylaniline and 4,4'-methylenebis(2-ethyl-6-methylaniline) in the repeating unit. In this embodiment, the polymer of aromatic amines is a formaldehyde polymer comprising at least one of 2-ethylaniline and 4,4'-methylenebis(2-ethylaniline) in the repeating unit.

[0070] Alkylphenol is (a) an alkylphenol having at least one ethyl group; or (b) an alkylphenol having 1 to 3 carbon atoms in its alkyl group and having at least one methyl group and one isopropyl group. The above (a) is an alkylphenol represented by the following formula (1), and the above (b) is an alkylphenol represented by the following formula (2).

[0071] .

[0072] (Where R1, R2, and R3 in formula (1) represent hydrogen or ethyl, and at least one of R1, R2, and R3 represents ethyl.) .

[0073] (Wherein, R1, R2, R3, R4 and R5 in formula (2) represent hydrogen or alkyl groups having 1 to 3 carbon atoms, at least one of R1, R2, R3, R4 and R5 represents methyl, and at least one of R1, R2, R3, R4 and R5 represents isopropyl.) In addition, in this embodiment, the alkylphenol contained in liquid B is carvacrol represented by formula (2).

[0074] The ratio of the ester equivalent of 3,4-dihydrocoumarin to the phenol equivalent of alkylphenol is 4.0 or more and 12.0 or less. Here, the phenol equivalent is determined by the following formula (e1). The ester equivalent is determined by the following formula (e2).

[0075] Phenol equivalent = molecular weight of phenol / number of hydroxyl groups… (e1)

[0076] Ester equivalent = molecular weight of lactone / 2…(e2)

[0077] It should be noted that 3,4-dihydrocoumarin, as a lactone, can be considered to undergo a ring-opening reaction during the curing process. Therefore, as will be described in detail later, in formula (e2), the value of dividing the molecular weight of the lactone by is set to "2".

[0078] Furthermore, the epoxy equivalent, described later, is determined using the following formula (e3). The amine equivalent, described later, is determined using the following formula (e4).

[0079] Epoxy equivalent = molecular weight of epoxy resin / number of epoxy groups… (e3)

[0080] Amine equivalent = molecular weight of amine / number of active hydrogen atoms in amine… (e4)

[0081] Adhesives with the above characteristics have low environmental impact, excellent liquid resistance, and cure at relatively low curing temperatures. It should be noted that 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane are isomers and will be collectively referred to as bis(aminomethyl)norbornene in the following description.

[0082] Liquid A contains a so-called bisphenol-free epoxy resin as its main agent. Therefore, compared to glycidyl ether type epoxy resins containing bisphenol, it can reduce environmental impact. This adhesive is particularly useful when printed on a medium 12 used for food packaging materials using a liquid jetting device 100.

[0083] Bisphenol-free epoxy resins exhibit low reactivity with polymers of aromatic amines. The inventors have discovered that by adding alkylphenols, 3,4-dihydrocoumarin, and bis(aminomethyl)norbornene to the bisphenol-free epoxy resin and the aromatic amine polymer, reactivity can be improved. This allows the adhesive to cure at a relatively low curing temperature. It should be noted that the curing temperature in this embodiment is approximately 80°C or lower. Because the adhesive of this application cures at a relatively low curing temperature (below 100°C), stress generation in the bonded materials can be reduced, even when bonding different materials.

[0084] Furthermore, the ratio of the ester equivalent of 3,4-dihydrocoumarin to the phenol equivalent of alkylphenol is 4.0 or more and 12.0 or less. This improves the liquid resistance of the cured compound GL and provides an adhesive that easily mixes liquids A and B.

[0085] Among the phenols in (a) or (b) above, several phenols, such as carvacrol, are highly safe. That is, this adhesive is safer because it can be made from ingredients that do not contain reproductively toxic substances such as nonylphenol.

[0086] Furthermore, in this embodiment, the ratio of the epoxy equivalent of the bisphenol-free epoxy resin to the ester equivalent of 3,4-dihydrocoumarin is 3.33 or more and 6.00 or less. This provides an adhesive that can be stored at room temperature for extended periods and exhibits excellent liquid resistance.

[0087] Furthermore, in this embodiment, the sum of the ratio of the phenol equivalent of phenol in (a) or (b) above to the amine equivalent of bis(aminomethyl)norbornene and the ratio of the ester equivalent of 3,4-dihydrocoumarin to the amine equivalent of bis(aminomethyl)norbornene is 0.75 or more and 1.167 or less. This improves the strength of the cured compound GL and enhances its liquid resistance.

[0088] Furthermore, in this embodiment, the sum of the ratio of the amine equivalent of the aromatic amine polymer to the epoxy equivalent of the bisphenol-free epoxy resin and the ratio of the amine equivalent of bis(aminomethyl)norbornene to the epoxy equivalent of the bisphenol-free epoxy resin is 1.16 or more and 1.40 or less. This improves the strength of the cured compound GL and enhances its liquid resistance.

[0089] As explained above, the two-component adhesive with the features described in this embodiment has low environmental impact, low curing temperature, and excellent liquid resistance. Due to the low curing temperature, stress generation in different materials after bonding can be reduced, even when bonding different types of materials. Furthermore, due to its excellent liquid resistance, as a liquid ejected from nozzle N, even when using inks with various properties, the reduction in the bond strength of the cured two-component adhesive GL can be suppressed, improving the reliability of the liquid ejector head 30. Additionally, due to its low environmental impact, printed materials printed using the liquid ejector device 100 can be used with confidence. Moreover, due to its ease of mixing and excellent shelf life at room temperature, the efficiency of the mixing and coating processes of liquid A and liquid B can be improved, reducing the time and labor required for storage.

[0090] It should be noted that the two-component adhesive used in the manufacture of the liquid injection head 30 is not limited to the embodiments described above. Specifically, the bisphenol-free epoxy resin included in the main agent is not limited to N,N,N',N'-tetraglycidyl-m-xylenediamine. For example, the bisphenol-free epoxy resin can be 4,4'-methylenebis(N,N-diglycidylaniline). Furthermore, the polymer of aromatic amines is not limited to formaldehyde polymers containing at least one of 2-ethylaniline and 4,4'-methylenebis(2-ethylaniline) in the repeating unit. The phenol in (a) or (b) above is not limited to carvacrol. For example, the phenol in (a) above can be 4-ethylphenol. For example, the phenol in (b) above can be 2-hydroxycymene, thymol, 3-hydroxycymene, o-cymene-5-ol, etc. When these components are used, since each component has the same chemical properties as the corresponding component in the above embodiments, it is possible to produce a two-component mixed adhesive that achieves the same effect as the above embodiments.

[0091] The ratio of the epoxy equivalent of the bisphenol-free epoxy resin to the ester equivalent of 3,4-dihydrocoumarin is not limited to 3.33 or more and 6.00 or less. Furthermore, the sum of the ratio of the phenol equivalent of the phenol in (a) or (b) above to the amine equivalent of bis(aminomethyl)norbornene and the ratio of the ester equivalent of 3,4-dihydrocoumarin to the amine equivalent of bis(aminomethyl)norbornene is not limited to 0.75 or more and 1.167 or less. Additionally, the sum of the ratio of the amine equivalent of the aromatic amine polymer to the epoxy equivalent of the bisphenol-free epoxy resin and the ratio of the amine equivalent of bis(aminomethyl)norbornene to the epoxy equivalent of the bisphenol-free epoxy resin is not limited to 1.16 or more and 1.40 or less.

[0092] B. Experimental Example: B1. Ingredients List: Figure 6 This provides a list of the ingredients used in the experiment. Figure 7 The chemical structural formulas (f1) and (f2) are shown. In this specification, each component is identified using a unique designation.

[0093] The CAS registration number for ingredient CA is 63738-22-7. For example... Figure 7 As shown in the chemical formula (f1), component CA is N,N,N',N'-tetraglycidyl-m-xylenediamine, an epoxy resin with a tetrafunctional group. In the experiment, TETRAD-X (registered trademark / product name) manufactured by Mitsubishi Gas Chemical Co., Ltd. was used as component CA.

[0094] The active ingredient CB is 3,4-dihydrocoumarin lactone, CAS Registry Number 119-84-6. In the experiment, the product manufactured by Tokyo Chemical Industry Co., Ltd. was used as active ingredient CB.

[0095] The CAS registration number for ingredient CC is 69178-41-2. For example... Figure 7 As shown in the chemical formula (f2), component CC is a polymer of aromatic amines. In chemical formula (f2), n is an integer greater than or equal to 2. In the experiment, KAYAHARD (registered trademark) AA (product name), manufactured by Nippon Kayaku Co., Ltd., was used as component CC.

[0096] Component CD is carvacrol, a phenol, with CAS registration number 499-75-2. In the experiment, a product manufactured by Tokyo Chemical Industry Co., Ltd. was used as component CD.

[0097] Component CE is a bis(aminomethyl)norbornene, an alicyclic amine, with CAS registration number 56602-77-8. Component CE is a mixture of isomers comprising 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane. In the experiment, a product manufactured by Tokyo Chemical Industry Co., Ltd. was used as component CE.

[0098] The molecular weight, reactive groups, number of reactive groups, and equivalent weight of each component are as follows: Figure 6 As shown. In the experiments described later, in order to achieve the desired equivalence ratio, the following methods were used. Figure 6 The equivalent shown includes mass calculations. It should be noted that... Figure 6 The number of reactive groups is consistent with the value of dividing the molecular weight in the above formulas (e1) to (e4) for calculating the equivalent amount. In addition, as mentioned above, since it can be assumed that component CB (3,4-dihydrocoumarin) undergoes a ring-opening reaction in the curing reaction, the number of reactive groups is set to "2".

[0099] By changing the composition of liquid A and liquid B and the equivalent ratio of the components contained in each liquid, solidified products were prepared, and experiments were conducted to evaluate the solidified products. Figure 8 This is a diagram used to illustrate the evaluation method. Figures 9-11 This is a graph summarizing the components and their equivalent ratios and mass ratios from the experiment. It should be noted that the mass ratios are equal to the masses of each component satisfying the equivalent ratio when the total mass of all components is set to 100g. Figures 9-11 The mass ratios shown in the figures are substantially the same as the equivalence ratios. The mass ratios are also included in this specification for reference.

[0100] In the experiment, two cured products were prepared under different curing conditions. The first curing condition was: curing temperature of 60℃ and curing time of 24 hours. The second curing condition was: curing temperature of 80℃ and curing time of 10 hours.

[0101] B2. Evaluation Explanation: B2-1. Preparation of evaluation materials: First, it was made Figure 8 The image shows a dumbbell-shaped cured product. The dumbbell shape is based on the Japanese Industrial Standard JIS K7139, Plastic-Test Sheet Type CP. Regarding the manufacturing method, firstly, a dumbbell-shaped mold was fabricated on a 3mm thick PTFE (polytetrafluoroethylene) sheet using machining.

[0102] Next, a mixture of liquid A and liquid B was prepared. Here, the method for preparing the cured product will be explained using Experimental Example 1 as an example. In this experiment, liquid A and liquid B were prepared separately and then stored either refrigerated or frozen. Furthermore, in preparing each experimental example, liquid A and liquid B were brought back to room temperature before mixing. It should be noted that when mixing the components of liquid A, due to the chemical reactions between the components, the viscosity of liquid A changes significantly with time, i.e., the rate of change of viscosity. The same applies to liquid B. Therefore, a treatment is generally performed to allow the chemical reaction to proceed until the rate of viscosity change slows down. This process of mixing the components and leaving them at the reaction temperature until the chemical reaction is largely complete is also called addition treatment and aging treatment. By performing addition treatment, even when liquid A and liquid B are returned to room temperature, it is difficult for each liquid to undergo a rapid change in viscosity, thus offering advantages such as the ability to effectively mix liquid A and liquid B and subsequently apply the coating. In this experiment, liquid A and liquid B were subjected to addition treatment separately and then stored either refrigerated or frozen.

[0103] In the case of producing liquid A, Figure 9The equivalence and mass ratios shown indicate that, firstly, components CA and CB, which are epoxy resins, are mixed and subjected to an addition treatment at 80°C for 2 hours to allow for localized reaction. Then, the prepared solution A is stored refrigerated or frozen.

[0104] In the case of producing solution B, Figure 9 The equivalence and mass ratios shown indicate that component CC (an aromatic amine) and component CD (an alkylphenol) are mixed and left at room temperature for 30 minutes. Then, component CE is added to the mixture as an addition treatment, and the mixture is left to react at 80°C for 2 hours. The resulting solution B is then stored refrigerated or frozen.

[0105] As described above, after bringing liquid A and liquid B to room temperature respectively, they are mixed. It should be noted that in this experiment, liquid A and liquid B were prepared using a method of refrigeration or freezing after the addition treatment, but this method is optional. As mentioned above, the purpose of the addition treatment is to improve the workability of mixing liquid A and liquid B, etc. Omitting the addition treatment does not affect the adhesive's properties such as liquid resistance and curing properties. Furthermore, refrigeration or freezing of liquid A and liquid B is not necessary. The purpose of refrigeration or freezing of liquid A and liquid B is to inhibit the individual chemical reactions of liquid A and liquid B. Therefore, if liquid A and liquid B are mixed separately beforehand, or if liquid A or liquid B has low reactivity even at room temperature, refrigeration or freezing is not required.

[0106] It should be noted that in Experiments 2 to 16, the preparation method of the mixture of liquid A and liquid B is the same as that in Experiment 1.

[0107] Pour the mixture of liquids A and B into a dumbbell-shaped mold, and remove any overflowing mixture using a PTFE scraper. With the cured product prepared under the first curing conditions, immerse the PTFE sheet containing the mixture of liquids A and B in a constant temperature bath at room temperature. After 30 minutes, raise the temperature bath to 60°C. Then, heat the mixture in the constant temperature bath at 60°C for 24 hours to cure the mixture of liquids A and B. After stopping heating, leave the cured product in the constant temperature bath for 5 hours. Once the temperature of the constant temperature bath has dropped to approximately 40°C, remove the cured product and place it at room temperature. Then, deform the PTFE sheet and remove the cured product.

[0108] In the case of producing a cured product under the second curing condition, a PTFE sheet containing a mixture of liquid A and liquid B in a mold is placed into a constant temperature bath at room temperature. After 30 minutes, the temperature of the constant temperature bath is raised to 80°C. Then, it is heated in the constant temperature bath at 80°C for 10 hours to cure the mixture of liquid A and liquid B. After heating is stopped, the cured product is left in the constant temperature bath for 5 hours. After the temperature of the constant temperature bath drops to about 40°C, the cured product is removed and placed in a room temperature environment. Then, the PTFE sheet is deformed, and the cured product is removed.

[0109] Next, the prepared solidified material was immersed in the evaluation solution for 2 weeks. Specifically, the solidified material was placed in a 30ml LABORAN (registered trademark) spiral tube bottle, and the evaluation solution was injected in a manner that allowed the solidified material to be completely immersed. The bottle was then capped and placed in a constant temperature bath at 60°C for two weeks.

[0110] Three evaluation solutions, namely, the first evaluation solution and the third evaluation solution, were used as evaluation solutions. The first evaluation solution is a liquid simulating the coloring ink containing coloring material used in the liquid spraying device 100 described above. The composition and mass ratio of each component of the first evaluation solution are described below.

[0111] (First evaluation solution)

[0112] Ingredients: by mass

[0113] 3-Methyl-1,5-pentanediol (MPD): 10

[0114] OLFINE (registered trademark) E1010:1

[0115] Water: 84

[0116] Diethylene glycol monobutyl ether: 5

[0117] The second evaluation solution is a liquid that simulates the acidic pretreatment ink used in the liquid jetting device 100 described above. The composition and mass ratio of each component of the second evaluation solution are as follows. The lactic acid contained in the second evaluation solution is an organic acid, and the pH of the evaluation solution is approximately 2.

[0118] (Second evaluation solution)

[0119] Ingredients: by mass

[0120] 3-Methyl-1,5-pentanediol (MPD): 10

[0121] OLFINE (registered trademark) E1010:1

[0122] Water: 84

[0123] Lactic acid: 5

[0124] The third evaluation liquid is a liquid that simulates the UV ink used in the liquid jetting device 100 described above. The composition and mass of each component of the third evaluation liquid are as follows.

[0125] (Third evaluation solution)

[0126] Ingredients: by mass

[0127] Phenoxyethyl acrylate (PEA): 80

[0128] 4-Hydroxybutyl acrylate (4HBA): 20

[0129] It should be noted that the PEA mentioned above is a monomer, with CAS registration number 48145-04-6. The 4HBA mentioned above is a monomer, with CAS registration number 2478-10-6.

[0130] Next, the solidified material was separated from the evaluation solution using a getter-type filtration device. A PTFE membrane filter with a pore size of 10 μm was used as the filter. After washing the remaining solidified material on the funnel side with pure water and ethanol, while still containing trace amounts of solidified material, the solidified material was dried at 25°C for one day. The dried solidified material was then evaluated as follows. In the following description, the dried solidified material is sometimes referred to as the evaluation material.

[0131] B2-2. Evaluation (Tensive Breaking Strength): For the evaluation specimen, the tensile strength was determined using a tensile testing apparatus. The tensile testing apparatus used was an A&D STB-1225S. Specifically, parallel clamps were installed at both ends of the wide width of the dumbbell-shaped cured specimen, and the specimen was stretched at a speed of 0.5 mm / min until the cured specimen fractured. The tensile load at fracture was measured. Furthermore, the area of ​​the fracture surface was obtained using a KEYENCE VHX-6000 digital microscope. Using the obtained tensile load and the area of ​​the fracture surface, the fracture strength was calculated using the following formula (e5).

[0132] Fracture strength [MPa] = Tensile load [N] / Fracture area [mm] 2 ... (e5)

[0133] The better the liquid resistance of a cured material, the greater its tensile strength. Therefore, as described below, the tensile strength was evaluated using five grades: S, AA, A, B, and C. The grades of superior liquid resistance are represented in the order C, B, A, AA, and S.

[0134] S: Fracture strength is above 80MPa

[0135] AA: Tensile strength is above 60MPa and below 80MPa

[0136] A: Fracture strength is above 40MPa and below 60MPa

[0137] B: Fracture strength is above 20MPa and below 40MPa

[0138] C: Fracture strength less than 20MPa

[0139] It should be noted that the tensile strength of the cured material before it was immersed in the evaluation solution was also measured in the same manner as described above.

[0140] The following evaluation of the tensile strength of the cured material before immersion in the evaluation solution under the first curing condition (initial stage) is referred to as "Evaluation A (1)". For the evaluated material under the first curing condition, the evaluation of the tensile strength of the evaluated material using the first evaluation solution is referred to as "Evaluation B (1)". For the evaluated material under the first curing condition, the evaluation of the tensile strength of the evaluated material using the second evaluation solution is referred to as "Evaluation C (1)". For the evaluated material under the first curing condition, the evaluation of the tensile strength of the evaluated material using the third evaluation solution is referred to as "Evaluation D (1)".

[0141] The evaluation of the tensile strength of the cured material before immersion in the evaluation solution under the second curing condition is referred to as "Evaluation A (2)". For the evaluated material under the second curing condition, the evaluation of the tensile strength of the evaluated material using the first evaluation solution is referred to as "Evaluation B (2)". For the evaluated material under the second curing condition, the evaluation of the tensile strength of the evaluated material using the second evaluation solution is referred to as "Evaluation C (2)". For the evaluated material under the second curing condition, the evaluation of the tensile strength of the evaluated material using the third evaluation solution is referred to as "Evaluation D (2)".

[0142] The relationship between the above evaluations and the various conditions is summarized below.

[0143] (Evaluation) (Curing conditions) (Evaluation solution)

[0144] Evaluation A (1): First (60℃ for 24 hours) initial stage

[0145] Evaluation B (1): First (60℃ 24 hours) First evaluation solution (ether)

[0146] Evaluation C(1): First (60℃ for 24 hours) Second evaluation solution (acidic)

[0147] Evaluation D(1): First (60℃ 24 hours) Third evaluation solution (monomer)

[0148] Evaluation A (2): Second (80℃ for 10 hours) initial stage

[0149] Evaluation B (2): Second (80℃ for 10 hours) First evaluation solution (ether)

[0150] Evaluation C(2): Second (80℃ for 10 hours) Second evaluation solution (acidic)

[0151] Evaluation D(2): Second (80℃ for 10 hours) Third evaluation solution (monomer)

[0152] exist Figures 9-11 The values ​​of ratio (B / D), ratio (A / B), ratio ((B+D) / E), and ratio ((C+E) / A) are shown.

[0153] The ratio (B / D) refers to the ratio of the ester equivalent of component CB to the phenol equivalent of component CD. The ratio (A / B) refers to the ratio of the epoxy equivalent of component CA to the ester equivalent of component CB.

[0154] The ratio ((B+D) / E) refers to the sum of the ratio of the phenol equivalent of component CD to the amine equivalent of component CE, and the ratio of the ester equivalent of component CB to the amine equivalent of component CE.

[0155] The ratio ((C+E) / A) refers to the sum of the ratio of the amine equivalent of component CC to the epoxy equivalent of component CA, and the ratio of the amine equivalent of component CE to the epoxy equivalent of component CA.

[0156] Figure 12 It is a graph summarizing the evaluation results of each experimental example from Experiment 1 to Experiment 12. Figure 13 This is a graph summarizing the evaluation results of each experimental example from Experiment 13 to Experiment 16.

[0157] like Figure 9 as well as Figure 10 As shown, the ratio (B / D) of Experimental Examples 1 to 12 is 4.0 or higher and 12.0 or lower. Additionally, as... Figure 12 As shown, the evaluation results for Experiments 1 through 12 all received excellent ratings, all at grade A or higher. In contrast, as... Figure 11 As shown, the ratio (B / D) of Experimental Examples 13 to 16 is outside the range of 4.0 or higher and 12.0 or lower. Additionally, as... Figure 13 As shown, in the evaluation results of Experimental Examples 13 to 16, the evaluations other than Evaluation A(1) and Evaluation A(2) include grades below B. This result indicates that if the ratio (B / D) is in the range of 4.0 or higher and 12.0 or lower, good liquid resistance is exhibited.

[0158] The ratio (B / D) of Experimental Examples 13 and 15 is less than 4.0. That is, component CD (carvacrol) is more abundant than component CB (3,4-dihydrocoumarin). Here, component CD (carvacrol) has a hydroxyl group that facilitates the chemical reaction. In contrast, component CB (3,4-dihydrocoumarin) generates two binding sites in the ring-opening reaction. Specifically, the two binding sites refer to the oxygen atom within the ring and the carbon atom bonded to the oxygen atom via a double bond. Therefore, component CD (carvacrol) may decrease the degree of polymerization of the solidified product in the chemical reaction of solutions A and B. Component CB (3,4-dihydrocoumarin) may increase the degree of polymerization of the solidified product in the chemical reaction of solutions A and B.

[0159] The inventors confirmed that when the cured product was contacted with an acidic second evaluation solution, component CD (carvacrol) dissolved into the second evaluation solution. Therefore, it can be considered that although component CD (carvacrol) functions as a catalyst or promoter in the chemical reaction between solution A and solution B, it may not be embedded in the cured product. Alternatively, it can be considered that even if component CD (carvacrol) is embedded in the cured product, since it is embedded at the end of the molecular chain, it may detach from the molecular chain upon contact with the liquid and dissolve into the second evaluation solution. Thus, it can be concluded that component CD (carvacrol) does not contribute to the increase in the degree of polymerization of the cured product in the chemical reaction between solution A and solution B.

[0160] The inventors confirmed that the mixture of component CD (carvacrol) and component CE (bis(aminomethyl)norbornene) is a liquid. Furthermore, the inventors confirmed that the mixture of component CB (3,4-dihydrocoumarin) and component CE (bis(aminomethyl)norbornene) is a white, gel-like polymeric compound. Therefore, it can be considered that during the chemical reaction between liquids A and B, while component CB (3,4-dihydrocoumarin) and component CE (bis(aminomethyl)norbornene) react, this compound may also react with component CA (bisphenol-free epoxy resin). Therefore, it can be considered that components CB and CE are not embedded at the ends of the molecular chains of the cured product, but rather embedded within the molecular chains.

[0161] The ratio (B / D) of Experimental Example 13 and Experimental Example 15 is less than 4.0. The evaluation result of Evaluation C (2) for Experimental Example 13 and Experimental Example 15 is grade B. It can be considered that this is because there is more component CD (carvacrol) in Experimental Example 13 and Experimental Example 15, so the degree of polymerization of the solidified product is low, and component CD (carvacrol) becomes easier to dissolve.

[0162] In Experimental Examples 14 and 16, the ratio (B / D) is greater than 12.0. That is, relative to component CD (carvacrol), component CB (3,4-dihydrocoumarin) is more abundant. Component CB (3,4-dihydrocoumarin) has a lower viscosity than component CD (carvacrol), making it a very low-viscosity liquid. Therefore, if component CB (3,4-dihydrocoumarin) is more abundant, liquid A becomes low-viscosity. In this case, the viscosity difference between liquid A and liquid B becomes larger, making mixing liquid A and liquid B difficult, and therefore undesirable. It should be noted that in such cases where mixing liquid A and liquid B becomes difficult, mechanical mixing of liquid A and liquid B can be used in the manufacturing process.

[0163] Evaluation results D(2) of Experimental Examples 14 and 16 were grade B. This result indicates that if the number of sites in the cured product originating from component CB (3,4-dihydrocoumarin) increases, the cured product tends to have poor monomer resistance.

[0164] like Figure 9 as well as Figure 10 As shown, the ratio (A / B) of Experimental Examples 1 to 12 is 3.33 or higher and 6.0 or lower. Additionally, as... Figure 12 As shown, the evaluation results for Experiments 1 through 12 all received an excellent rating, which was A or higher. In contrast, as... Figure 11 As shown, the ratio (A / B) of Experimental Examples 13 to 16 falls outside the range of 3.33 or higher and 6.0 or lower. Additionally, as... Figure 13 As shown, in the evaluation results of Experimental Examples 13 to 16, the evaluations other than Evaluation A(1) and Evaluation A(2) include grades below Grade B. From this result, it can be seen that if the ratio (A / B) is in the range of 3.33 or higher and 6.0 or lower, good liquid resistance is exhibited.

[0165] In Experimental Examples 14 and 16, the ratio (A / B) is less than 4.0. That is, the content of component CB (3,4-dihydrocoumarin) is higher than that of component CA (bisphenol-free epoxy resin). If the content of component CB (3,4-dihydrocoumarin) is higher, the viscosity of solution A increases sharply when stored at room temperature. Therefore, if the ratio (A / B) is less than 4.0, the shelf life of solution A at room temperature decreases, making it less desirable.

[0166] Evaluation results D(2) of Experimental Examples 14 and 16 were grade B. This result indicates that if the number of sites in the cured product originating from component CB (3,4-dihydrocoumarin) increases, the cured product tends to have poor monomer resistance.

[0167] In Experimental Examples 13 and 15, the ratio (A / B) was greater than 6. That is, the component CB (3,4-dihydrocoumarin) was less than that of component CA (bisphenol-free epoxy resin). The evaluation result B(2) of Experimental Examples 13 and 15 was grade B. It can be assumed that this is because when the component CB (3,4-dihydrocoumarin) is less, curing under the second curing condition cannot proceed sufficiently.

[0168] like Figure 9 as well as Figure 10 As shown, the ratio ((B+D) / E) of Experimental Examples 1 to 12 is greater than 0.75 and less than 1.167. Furthermore, as... Figure 12 As shown, the evaluation results for Experiments 1 through 12 all received an excellent rating, which was A or higher. In contrast, as... Figure 11 As shown, the ratio (A / B) of Experimental Examples 13 to 16 is outside the range of 0.75 or higher and 1.167 or lower. Additionally, as... Figure 13 As shown, in the evaluation results of Experimental Examples 13 to 16, the evaluations other than Evaluation A(1) and Evaluation A(2) include grades below grade B. From this result, it can be seen that when the ratio ((B+D) / E) is in the range of 0.75 or higher and 1.167 or lower, it exhibits good liquid resistance.

[0169] In Experimental Examples 15 and 16, the ratio ((B+D) / E) was less than 0.75. That is, relative to the total amount of component CB (3,4-dihydrocoumarin) and component CD (carvacrol), component CE (bis(aminomethyl)norbornene) was more abundant. When component CE (bis(aminomethyl)norbornene) was more abundant, the mixture of solution A and solution B thickened rapidly, which is not preferred.

[0170] Evaluation results C(2) and D(2) of Experimental Examples 15 and 16 were both grade B. This result indicates that when the non-aromatic component CE (bis(aminomethyl)norbornene) is present in large quantities, the cured product tends to have poor acid resistance and monomer resistance. Furthermore, if component CE is present in large quantities, the reaction between solution A and solution B occurs unevenly, suggesting the presence of locally weak areas in the cured product. Therefore, these weak areas can be considered to contribute to reduced acid resistance and monomer resistance.

[0171] In Experimental Examples 13 and 14, the ratio ((B+D) / E) was greater than 1.17. That is, relative to the total amount of component CB (3,4-dihydrocoumarin) and component CD (carvacrol), component CE (bis(aminomethyl)norbornene) was relatively low. The evaluation results of Evaluation C (1) and Evaluation D (1) of Experimental Examples 13 and 14 were both grade C. In addition, the evaluation result of Evaluation A (2) of Experimental Examples 13 and 14 was grade A, which was worse than the evaluation results of Experimental Examples 1 to 12. Component CE (bis(aminomethyl)norbornene) had high reactivity with component CA (bisphenol-free epoxy resin). Therefore, it can be considered that component CE helps to achieve the curing reaction at a low curing temperature. Therefore, when component CE is relatively low, it can be considered that the curing reaction at the curing temperature in the experiment cannot proceed sufficiently. Especially under the first curing condition, since the curing reaction cannot proceed sufficiently, it can be considered that the acid resistance and monomer resistance of the cured product are greatly reduced.

[0172] like Figure 9 as well as Figure 10 As shown, the ratio ((C+E) / A) of Experimental Examples 1 to 12 is greater than 1.16 and less than 1.40. Furthermore, as... Figure 12 As shown, the evaluation results of evaluation A(1) and evaluation A(2) in Experiments 1 to 12 are grade S or grade AA. In contrast, as Figure 11 As shown, the ratio ((C+E) / A) of Experimental Examples 13 to 16 is outside the range of 1.16 or higher and 1.40 or lower. Additionally, as... Figure 13 As shown, the evaluation results of Evaluation A(1) and Evaluation A(2) in Experimental Examples 13 to 16 include Grade A. From this result, it can be seen that if the ratio ((C+E) / A) is in the range of 1.16 or higher and 1.40 or lower, it exhibits good liquid resistance.

[0173] In the curing reaction, it can be assumed that the epoxy groups in component CA (bisphenol-free epoxy resin) react with the amino groups in components CC (polymer of aromatic amines) and CE (bis(aminomethyl)norbornene) to form a cross-linked structure of the cured product. Therefore, it can be considered that when the ratio of the epoxy equivalent of component CA to the amine equivalent of components CC and CE deviates significantly from "1", the cross-linked structure cannot be fully formed, resulting in a decrease in the performance of the cured product.

[0174] In Experimental Examples 13 and 14, the ratio ((C+E) / A) was less than 1.16. That is, relative to the total amount of component CC (polymer of aromatic amines) and component CE (bis(aminomethyl)norbornene), component CA (bisphenol-free epoxy resin) was more abundant. Therefore, the epoxy groups of component CA (bisphenol-free epoxy resin) remained unreacted, resulting in a reduced number of crosslinking points in the cured product. Consequently, the initial and subsequent tensile strength of the cured product decreased. Furthermore, if the number of crosslinking points in the cured product decreased, the glass transition temperature (Tg) of the cured product decreased, which is undesirable.

[0175] In Experimental Examples 15 and 16, the ratio ((C+E) / A) was greater than 1.40. That is, relative to the total amount of component CC (polymer of aromatic amines) and component CE (bis(aminomethyl)norbornene), component CA (bisphenol-free epoxy resin) was less. Therefore, the amino groups of components CC and CE remained unreacted, resulting in a reduced number of crosslinking points in the cured product. Consequently, the initial tensile strength of the cured product and its resistance to liquid were reduced. Furthermore, the amino groups might not react with the epoxy groups but react with component CB (3,4-dihydrocoumarin). In this case, it can be considered that the number of epoxy-derived sites in the cured product was relatively reduced, thus leading to decreased liquid resistance.

[0176] C. Other implementation methods: (C1) In the above embodiment, an embodiment in which a two-component mixed adhesive is applied to a liquid injection head 30 is shown; however, the component to which the two-component mixed adhesive is applied is not limited to the liquid injection head 30. Furthermore, in the above embodiment, the adhesive does not contain fillers, but the adhesive may also contain fillers for adjusting viscosity.

[0177] It should be noted that the two-component mixed adhesive used in the manufacture of the liquid injection head 30 is not limited to the embodiments described above. Specifically, the bisphenol-free epoxy resin is not limited to tetrafunctional glycidylamine type epoxy resin. The tetrafunctional glycidylamine type epoxy resin is not limited to N,N,N',N'-tetraglycidyl-m-xylenediamine and 4,4'-methylenebis(N,N-diglycidylaniline). The bisphenol-free epoxy resin may also contain a variety of epoxy resins. When using these components, since these components have the same chemical properties as the corresponding components in the above embodiments, it is possible to produce a two-component mixed adhesive that performs the same effect as in the above embodiments.

[0178] D. Other methods: This disclosure is not limited to the embodiments described above, and can be implemented in various structures without departing from its spirit. For example, in order to solve some or all of the above-described technical problems, or to achieve some or all of the above-described effects, the technical features of the embodiments corresponding to the technical features in the various methods described below can be appropriately replaced or combined. In addition, if a technical feature is not required to be described in this specification, it can be appropriately deleted.

[0179] (1) According to a first embodiment of the present disclosure, a liquid injection head for spraying liquid from a nozzle is provided. The liquid injection head includes a first component, a second component, and a cured product of a two-component mixed adhesive for bonding the first component and the second component, the two-component mixed adhesive comprising: a liquid A comprising a main agent comprising a bisphenol-free epoxy resin and 3,4-dihydrocoumarin; and a liquid B comprising at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, a polymer of an aromatic amine, and an alkylphenol, wherein the alkylphenol is: (a) an alkylphenol having at least one ethyl group; or (b) an alkylphenol having 1 to 3 carbon atoms and having at least one methyl group and one isopropyl group, wherein the ratio of the ester equivalent of the 3,4-dihydrocoumarin to the phenol equivalent of the alkylphenol is 4.0 or more and 12.0 or less. According to this method, by using an epoxy resin without bisphenol as the main agent, the environmental impact can be reduced. Furthermore, by including at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 3,4-dihydrocoumarin, and alkylphenol in the two-component adhesive, the two-component adhesive can be cured at a relatively low curing temperature. Therefore, even when bonding different types of materials, stress generation in the bonded materials can be reduced. Additionally, by ensuring that the ratio of the ester equivalent of 3,4-dihydrocoumarin to the phenol equivalent of the alkylphenol is 4.0 or more and 12.0 or less, the cured product exhibits excellent strength and excellent liquid resistance. Therefore, a highly reliable liquid injection head can be provided.

[0180] (2) Alternatively, in the above embodiments, the alkylphenol may be carvacrol. In this case, carvacrol emits a pleasant odor, and is therefore preferred from the viewpoint of use in the adhesive manufacturing process.

[0181] (3) Alternatively, in the above-described manner, the ratio of the epoxy equivalent of the bisphenol-free epoxy resin to the ester equivalent of the 3,4-dihydrocoumarin is 3.33 or more and 6.00 or less. According to this method, a two-component mixed adhesive with excellent shelf life and liquid resistance at room temperature can be provided.

[0182] (4) Alternatively, in the above-described manner, the sum of the ratio of the phenol equivalent of the alkylphenol to the amine equivalents of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, and the ratio of the ester equivalent of the 3,4-dihydrocoumarin to the amine equivalents of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, is 0.75 or more and 1.167 or less. According to this method, a two-component mixed adhesive that is easy to handle and has excellent liquid resistance can be provided.

[0183] (5) Alternatively, in the above-described manner, the sum of the ratio of the amine equivalent of the aromatic amine polymer to the epoxy equivalent of the bisphenol-free epoxy resin and the ratio of the amine equivalents of the 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and the 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane to the epoxy equivalent of the bisphenol-free epoxy resin is 1.16 or more and 1.40 or less. According to this method, a cured product with excellent strength and excellent liquid resistance can be provided.

[0184] (6) Alternatively, in the above manner, the polymer of the aromatic amine may comprise: a formaldehyde polymer in which at least one of 2-ethylaniline and 4,4'-methylenebis(2-ethylaniline) is contained in the repeating unit; or a formaldehyde polymer in which at least one of 2-ethyl-6-methylaniline and 4,4'-methylenebis(2-ethyl-6-methylaniline) is contained in the repeating unit.

[0185] (7) Alternatively, in the above manner, (a) is an alkylphenol represented by the above formula (1), and (b) is an alkylphenol represented by the above formula (2).

[0186] (Where R1, R2, and R3 in formula (1) represent hydrogen or ethyl, and at least one of R1, R2, and R3 represents ethyl.)

[0187] (Wherein, R1, R2, R3, R4 and R5 in formula (2) represent hydrogen or alkyl groups having 1 to 3 carbon atoms, at least one of R1, R2, R3, R4 and R5 represents methyl, and at least one of R1, R2, R3, R4 and R5 represents isopropyl.)

[0188] (8) Alternatively, in the above manner, the bisphenol-free epoxy resin is a tetrafunctional glycidylamine type epoxy resin.

[0189] (9) Alternatively, in the above manner, the tetrafunctional glycidylamine epoxy resin is at least one of N,N,N',N'-tetraglycidyl-m-xylenediamine and 4,4'-methylenebis(N,N-diglycidylaniline).

[0190] (10) Alternatively, in the above manner, the first component and the second component are respectively connected to the nozzle and define the flow path of the liquid flow, and the solidified material connects the flow path of the first component and the flow path of the second component in a liquid-tight manner.

[0191] (11) According to a second aspect of this disclosure, a two-component mixed adhesive is provided. The two-component mixed adhesive comprises: a liquid A containing a main agent comprising a bisphenol-free epoxy resin and 3,4-dihydrocoumarin; and a liquid B containing at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, a polymer of an aromatic amine, and an alkylphenol, wherein the alkylphenol is: (a) an alkylphenol having at least one ethyl group; or (b) an alkylphenol having 1 to 3 carbon atoms and having at least one methyl group and one isopropyl group, wherein the ratio of the ester equivalent of the 3,4-dihydrocoumarin to the phenol equivalent of the alkylphenol is 4.0 or more and 12.0 or less. According to this aspect, by using a bisphenol-free epoxy resin as the main agent, the environmental impact can be reduced. Furthermore, by including at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 3,4-dihydrocoumarin, and alkylphenol in the two-component adhesive, the two-component adhesive can be cured at a relatively low curing temperature. Therefore, even when bonding different types of materials, stress generation in the bonded materials can be reduced. Additionally, by ensuring that the ratio of the ester equivalent of 3,4-dihydrocoumarin to the phenol equivalent of the alkylphenol is 4.0 or more and 12.0 or less, the cured product exhibits excellent strength and excellent liquid resistance.

[0192] (12) Alternatively, in the above embodiments, (a) is an alkylphenol represented by formula (1) above, and (b) is an alkylphenol represented by formula (2) above. (Wherein R1, R2, and R3 in formula (1) represent hydrogen or ethyl, and at least one of R1, R2, and R3 represents ethyl.)

[0193] (wherein, R1, R2, R3, R4 and R5 in formula (2) represent hydrogen or alkyl groups having 1 to 3 carbon atoms, at least one of R1, R2, R3, R4 and R5 represents methyl, and at least one of R1, R2, R3, R4 and R5 represents isopropyl).

Claims

1. A liquid injection head, characterized in that, Liquid is ejected from the nozzle. The liquid injection head includes a first component, a second component, and a cured product of a two-component adhesive bonding the first component and the second component. The two-component hybrid adhesive comprises: Solution A contains a main agent, which includes a bisphenol-free epoxy resin and 3,4-dihydrocoumarin; and Solution B comprises at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, a polymer of an aromatic amine, and an alkylphenol. The alkylphenol is: (a) An alkylphenol having at least one ethyl group; or (b) Alkylphenols having 1 to 3 carbon atoms and having at least one methyl group and one isopropyl group, The ratio of the ester equivalent of the 3,4-dihydrocoumarin to the phenol equivalent of the alkylphenol is 4.0 or more and 12.0 or less.

2. The liquid injection head according to claim 1, characterized in that, The alkylphenol is carvacrol.

3. The liquid injection head according to claim 1, characterized in that, The ratio of the epoxy equivalent of the bisphenol-free epoxy resin to the ester equivalent of the 3,4-dihydrocoumarin is 3.33 or more and 6.00 or less.

4. The liquid injection head according to claim 1, characterized in that, The sum of the ratio of the phenol equivalent of the alkylphenol to the amine equivalents of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane and the ratio of the ester equivalent of the 3,4-dihydrocoumarin to the amine equivalents of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane is 0.75 or more and 1.167 or less.

5. The liquid injection head according to claim 1, characterized in that, The sum of the ratio of the amine equivalent of the polymer of the aromatic amine to the epoxy equivalent of the bisphenol-free epoxy resin and the ratio of the amine equivalent of the polymer of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and the epoxy equivalent of the polymer of 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane to the epoxy equivalent of the bisphenol-free epoxy resin is 1.16 or more and 1.40 or less.

6. The liquid injection head according to claim 1, characterized in that, The polymer of the aromatic amine comprises: A formaldehyde polymer comprising at least one of 2-ethylaniline and 4,4'-methylenebis(2-ethylaniline) in the repeating unit; or The repeating unit contains a formaldehyde polymer of at least one of 2-ethyl-6-methylaniline and 4,4'-methylenebis(2-ethyl-6-methylaniline).

7. The liquid injection head according to claim 1, characterized in that, The (a) is an alkylphenol represented by the following formula (1), and the (b) is an alkylphenol represented by the following formula (2). 。 In formula (1), R1, R2, and R3 represent hydrogen or ethyl, and at least one of R1, R2, and R3 represents ethyl. 。 In formula (2), R1, R2, R3, R4 and R5 represent hydrogen or alkyl groups having 1 to 3 carbon atoms, at least one of R1, R2, R3, R4 and R5 represents methyl, and at least one of R1, R2, R3, R4 and R5 represents isopropyl.

8. The liquid injection head according to claim 1, characterized in that, The bisphenol-free epoxy resin is a tetrafunctional glycidylamine type epoxy resin.

9. The liquid injection head according to claim 8, characterized in that, The tetrafunctional glycidylamine type epoxy resin is at least one of N,N,N',N'-tetraglycidyl-m-xylenediamine and 4,4'-methylenebis(N,N-diglycidylaniline).

10. The liquid injection head according to claim 1, characterized in that, The first component and the second component are respectively connected to the nozzle and define the flow path for the liquid. The solidified material connects the flow paths of the first component and the second component in a liquid-tight manner.

11. A two-component mixed adhesive, characterized in that, have: Solution A contains a main agent, which includes a bisphenol-free epoxy resin and 3,4-dihydrocoumarin; and Solution B comprises at least one of 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane and 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, a polymer of an aromatic amine, and an alkylphenol. The alkylphenol is: (a) An alkylphenol having at least one ethyl group; or (b) Alkylphenols having 1 to 3 carbon atoms and having at least one methyl group and one isopropyl group, The ratio of the ester equivalent of the 3,4-dihydrocoumarin to the phenol equivalent of the alkylphenol is 4.0 or more and 12.0 or less.

12. The two-component mixed adhesive according to claim 11, characterized in that, The (a) is an alkylphenol represented by the following formula (1), and the (b) is an alkylphenol represented by the following formula (2). 。 In formula (1), R1, R2, and R3 represent hydrogen or ethyl, and at least one of R1, R2, and R3 represents ethyl. 。 In formula (2), R1, R2, R3, R4 and R5 represent hydrogen or alkyl groups having 1 to 3 carbon atoms, at least one of R1, R2, R3, R4 and R5 represents methyl, and at least one of R1, R2, R3, R4 and R5 represents isopropyl.

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