Epoxy resin composition, cured product, and bonded body

Abstract

Provided is an epoxy resin composition which, when used as an adhesive for bonding members to each other, is capable of suppressing positional displacement between the members and suppressing thermal degradation of the members. The epoxy resin composition contains an epoxy resin, a polythiol, a photobase generator, and a sensitizer, and also contains one or more epoxy resins, at least one of the epoxy resins has two or more epoxy groups in one molecule, the polythiol contains an ester bond and has five or more mercapto groups, and the photobase generator contains a photobase. Alternatively, the polythiol contains a nitrogen atom and the mercapto group is bonded to the nitrogen atom via the alkylene group.

Description

Technical Field

[0001] This invention relates to epoxy resin compositions, cured products, and bonding agents. Background Technology

[0002] Typically, electronic components, such as inkjet heads, are formed by bonding multiple parts together using adhesives. The adhesives used for inkjet heads need to have excellent ink resistance and adhesion. Therefore, epoxy resin compositions can be used as this adhesive. Epoxy resin compositions contain epoxy resin, curing agents, etc., and are cured through a polymerization reaction involving heat and light.

[0003] When using an epoxy resin composition as an adhesive to bond inkjet head components together, temporary fixing is performed in a first stage and formal curing is performed in a second stage to suppress positional misalignment. Furthermore, the temporary fixing in the first stage is sometimes performed by curing the adhesive with light and heat. Furthermore, the formal curing in the second stage is sometimes performed by further curing the adhesive with heat. Therefore, as an adhesive for bonding components together in both stages, an epoxy resin composition comprising epoxy resin, a photoalkali-generating agent, and a specific polythiol has been proposed (see, for example, Patent Document 1).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2021-113263 Summary of the Invention

[0005] In addition, when bonding the inkjet head components together, it is necessary to avoid "positional misalignment" that causes the components to become misaligned. Furthermore, it is necessary to prevent the components from deteriorating due to the heat during the curing process when bonding the components together.

[0006] While the epoxy resin composition in Patent Document 1 can achieve effects such as rapid temporary fixation in the first stage, further improvements are needed in suppressing positional displacement and component deterioration.

[0007] The present invention was made in view of the above-mentioned problems and circumstances. The problem solved by the present invention is to provide an epoxy resin composition that, when used as an adhesive for bonding components of an inkjet head to each other, can suppress positional misalignment of the components and suppress thermal degradation of the components.

[0008] To address the aforementioned issues, the inventors conducted in-depth research focusing on the structures of epoxy resins and curing agents. The results showed that by using a difunctional or higher-functional epoxy resin and a polythiol with a specific structure as a curing agent, component displacement and degradation could be suppressed, thus completing the present invention. In other words, the aforementioned issues involved in this invention can be resolved by the following means.

[0009] 1. An epoxy resin composition, characterized in that it comprises an epoxy resin, a polythiol, a photoalkali-generating agent, and a sensitizer, and,

[0010] The product comprises one or more of the above-mentioned epoxy resins, wherein at least one of the epoxy resins has two or more epoxy groups in one molecule.

[0011] The aforementioned polythiol contains an ester bond and has five or more thiol groups, or the aforementioned polythiol contains a nitrogen atom and the thiol group is bonded to the nitrogen atom via an alkylene group.

[0012] 2. The epoxy resin composition according to claim 1, characterized in that the polythiol, wherein the mercapto group is bonded to the nitrogen atom via an alkylene group, has a glycourea backbone.

[0013] 3. The epoxy resin composition according to claim 1, characterized in that at least one of the epoxy resins has three or more epoxy groups in its molecule.

[0014] 4. The epoxy resin composition according to claim 1, characterized in that the epoxy resin is a glycidylamine-based epoxy resin.

[0015] 5. The epoxy resin composition according to claim 1, characterized in that it comprises one or more of the above-mentioned photoalkali-generating agents, at least one of the above-mentioned photoalkali-generating agents having a borate.

[0016] 6. The epoxy resin composition according to claim 1, characterized in that the content of the above-mentioned photoalkali-generating agent is in a ratio of 3 to 10 equivalents of epoxy resin.

[0017] 7. The epoxy resin composition according to claim 1, comprising one or more of the above-mentioned sensitizers, wherein at least one of the above-mentioned sensitizers is 2-isopropylthioxanthone or 2-ethylanthraquinone.

[0018] 8. The epoxy resin composition according to claim 1, wherein it comprises a silane coupling agent.

[0019] 9. The epoxy resin composition according to claim 8, wherein the silane coupling agent is a compound having an epoxy or amine group, or an isocyanate.

[0020] 10. A cured product, which is a reactant of the epoxy resin composition described in any one of claims 1 to 9.

[0021] 11. The solidified product according to item 10, wherein the nitrogen content is 7.5 to 11% by mass and the sulfur content is 10 to 17% by mass.

[0022] 12. A joint comprising the cured material described in claim 10.

[0023] In the epoxy resin composition of the present invention, the polythiol contains an ester bond and has five or more mercapto groups, or the polythiol contains a nitrogen atom and the mercapto group is bonded to the nitrogen atom via an alkylene group. Therefore, the epoxy resin composition of the present invention exhibits a very fast reaction rate during curing. Consequently, when used as an adhesive for bonding inkjet head components together, component misalignment can be suppressed. Furthermore, because the epoxy resin composition of the present invention has a fast reaction rate, it can cure at low temperatures; therefore, when used as an adhesive for bonding inkjet head components together, heat-induced component deterioration can be suppressed. That is, when bonding inkjet head components together, it is preferable to use an adhesive containing the epoxy resin composition of the present invention.

[0024] The mechanism by which the effects of this invention are manifested or functioned is not yet clear, but the following is a conjecture.

[0025] When polythiols contain ester bonds and have more than five thiol groups, there are a moderate number of thiol groups serving as reaction sites. Therefore, it is speculated that the reaction rate is accelerated, enabling suppression of position shifts and low-temperature reactions.

[0026] In addition, when polythiols contain nitrogen atoms and the mercapto group is bonded to the nitrogen atom via an alkylene group, it is speculated that the special structure of the polythiols helps to increase the reaction rate. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating one embodiment of the joint of the present invention.

[0028] Figure 2 This is a schematic diagram illustrating other embodiments of the joint of the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1. Inkjet head

[0031] 2 Nozzle Plate

[0032] 3 Nozzle orifice

[0033] 4. Base plate

[0034] 5. Cured products of epoxy resin compositions

[0035] 6. Part of the camera module

[0036] 7 PC chips

[0037] 8 base plates

[0038] 9. Cured products of epoxy resin compositions Detailed Implementation

[0039] One embodiment of the epoxy resin composition of the present invention is an epoxy resin composition comprising an epoxy resin, a polythiol, a photoalkali-generating agent, and a sensitizer. Furthermore, the epoxy resin composition of this embodiment comprises one or more of the above-mentioned epoxy resins, at least one of which has two or more epoxy groups in one molecule. Furthermore, in the epoxy resin composition of this embodiment, the polythiol is either a first polythiol or a second polythiol. The first polythiol is a polythiol containing an ester bond and having five or more thiol groups. The second polythiol is a polythiol containing a nitrogen atom, and the thiol group is bonded to the nitrogen atom via an alkylene group. In this specification, when referring to "first polythiol or second polythiol," it means first polythiol, second polythiol, or "both first polythiol and second polythiol." In the case of "both first polythiol and second polythiol," the ratio of the two is not particularly limited. Furthermore, in the epoxy resin composition of this embodiment, the alkylene group is linear, consisting of a group formed by removing a hydrogen atom from each of the carbon atoms at both ends of a linear alkane and bonding it to other atoms. Additionally, the thiol group is bonded to one of the carbon atoms at both ends of the linear alkylene group, and the nitrogen atom is bonded to the other. These features are common or corresponding technical features in the following embodiments.

[0040] The aforementioned polythiols bonded to nitrogen atoms via alkylene groups preferably have a glycourea backbone. In the epoxy resin composition of this embodiment, since the polythiols have a glycourea backbone, the reaction rate during curing is accelerated, thus suppressing component displacement. Furthermore, as described above, if the reaction rate during curing is accelerated, the curing temperature can be lowered, thus suppressing thermal degradation of the component.

[0041] At least one of the above-mentioned epoxy resins preferably has three or more epoxy groups in its molecule. By having three or more epoxy groups in the molecule, the number of reaction sites increases when the epoxy resin composition is polymerized and cured, thus increasing the crosslinking density and improving ink resistance. In this specification, the polymerization of the epoxy resin composition by light to cure it is also referred to as a curing reaction.

[0042] The epoxy resin mentioned above is preferably glycidylamine-based. Because the epoxy resin is glycidylamine-based, it can accelerate the reaction rate during curing, and further improve ink resistance by increasing the crosslinking density.

[0043] The epoxy resin composition of this embodiment contains one or more of the above-mentioned photoalkali-generating agents, preferably at least one of which is a borate. Since at least one of the photoalkali-generating agents is a borate, the reaction can be carried out using UV curing.

[0044] The content of the aforementioned photoalkali-generating agent relative to 100 equivalents of epoxy resin is preferably a ratio of 3 to 10 equivalents. That is, the content of the aforementioned photoalkali-generating agent relative to 1 gram equivalent of epoxy resin is preferably a ratio of 3 / 100 to 10 / 100 gram equivalents.

[0045] The epoxy resin composition of this embodiment contains one or more of the above-mentioned sensitizers. Preferably, at least one of the sensitizers is 2-isopropylthioxanthone or 2-ethylanthraquinone. Thus, the photoalkalizing agent can exhibit photosensitivity in the long wavelength region (around 365 nm) and accelerate the reaction.

[0046] The epoxy resin composition of this embodiment preferably contains a silane coupling agent. This improves adhesion.

[0047] The aforementioned silane coupling agent is preferably a compound having epoxy or amino groups, or an isocyanate. This improves adhesion and extends usable time.

[0048] One embodiment of the cured product of the present invention is a reactant of the above-described epoxy resin composition. Since the cured product of this embodiment is a reactant of the epoxy resin composition of this embodiment, degradation during the reaction is suppressed, resulting in a cured product with a low degree of degradation. Furthermore, the cured product of this embodiment can suppress degradation caused by solvents, etc.

[0049] In the cured product of this embodiment, the nitrogen content is preferably 7.5 to 11% by mass. Furthermore, the sulfur content in the cured product of this embodiment is preferably 10 to 17% by mass. Given that the nitrogen content in the cured product of this embodiment is 7.5 to 11% by mass and the sulfur content is 10 to 17% by mass, it can be seen that the polythiol content in the epoxy resin composition before curing is the preferred content of the epoxy resin composition of this embodiment.

[0050] One embodiment of the joint of the present invention includes the cured material of this embodiment described above. Since the joint of this embodiment includes the cured material of this embodiment, positional displacement of the components constituting the joint is suppressed. Furthermore, since the cured material of this embodiment is a cured material with low degradation, degradation is also suppressed in the joint of this embodiment, making it a cured material with low degradation.

[0051] The present invention, its constituent elements, and the methods and forms of implementing the invention will be described in detail below. Furthermore, in this specification, the numerical range indicated by "~" refers to the range including the values ​​before and after it as a lower limit and an upper limit.

[0052] 1. Epoxy resin composition

[0053] <Epoxy Resin>

[0054] The epoxy resin composition of this embodiment comprises one or more epoxy resins. The epoxy resin can be one type or multiple types. Furthermore, at least one of the epoxy resins has two or more epoxy groups in one molecule. Examples of epoxy resins having two epoxy groups in one molecule include bisphenol F type epoxy resin and bisphenol A type epoxy resin.

[0055] At least one of the above-mentioned epoxy resins preferably has three or more epoxy groups in its molecule. Examples of epoxy resins having three epoxy groups per molecule include triglycidyl-p-aminophenol, triglycidyl isocyanurate, triglycidylurazole, triglycidylaminocresol, and resorcinol triglycidyl ether. Examples of epoxy resins having four epoxy groups per molecule include tetraglycidyl diaminodiphenylmethane and tetraglycidyl-1,3-diaminomethylcyclohexane. Furthermore, examples of epoxy resins having three or more epoxy groups per molecule include phenolic varnish-type epoxy resins and cresol varnish-type epoxy resins. Additionally, glycidylamine-based epoxy resins are preferred among the above-mentioned epoxy resins. In particular, triglycidyl-p-aminophenol is a preferred embodiment. Thus, since at least one of the epoxy resins has three or more epoxy groups in its molecule, when the epoxy resin composition is polymerized and cured, the crosslinking density increases due to the increased number of reaction points, thereby improving ink resistance.

[0056] <Polythiol>

[0057] The epoxy resin composition of this embodiment includes a polythiol as a curing agent. This polythiol is either a polythiol containing an ester bond and having five or more thiol groups, or a polythiol containing a nitrogen atom and having thiol groups bonded to the nitrogen atom via an alkylene group. Polythiools containing an ester bond and having five or more thiol groups, as described above, are sometimes referred to as first polythiols. Additionally, polythiools containing a nitrogen atom and having thiol groups bonded to the nitrogen atom via an alkylene group, as described above, are sometimes referred to as second polythiols.

[0058] In the epoxy resin composition of this embodiment, the alkylene group is a structural unit represented by the following formula (1).

[0059]

[0060] In the above formula (1), n ​​is an integer from 2 to 3.

[0061] As described above, the epoxy resin composition of this embodiment contains either a first polythiol or a second polythiol. Therefore, the epoxy resin composition of this embodiment exhibits a very fast reaction rate during curing. Consequently, when used as an adhesive for bonding inkjet head components together, component misalignment can be suppressed. Furthermore, because the epoxy resin of the present invention has a fast reaction rate, it can undergo a curing reaction at low temperatures. Therefore, when used as an adhesive for bonding inkjet head components together, component deterioration can be suppressed.

[0062] When polythiols contain ester bonds and have more than five thiol groups, it is speculated that the reaction rate is accelerated due to the moderate number of thiol groups serving as reaction sites, enabling positional shift suppression and low-temperature reactions. Furthermore, when polythiols contain nitrogen atoms and the thiol groups are bonded to the nitrogen atoms via alkylene groups, it is speculated that the special structure of this polythiols contributes to increasing the reaction rate.

[0063] As the first polythiol mentioned above, considering its fast reaction rate, dipentaerythritol hexa(3-mercaptopropionate) and others can be cited.

[0064] Examples of the aforementioned second polythiol include 1,3,4,6-tetra(2-mercaptopropyl)glyurea and 1,3,4,6-tetra(2-mercaptoethyl)glyurea. Among these, 1,3,4,6-tetra(2-mercaptopropyl)glyurea or 1,3,4,6-tetra(2-mercaptoethyl)glyurea are preferred for their fast reaction rate. Furthermore, 1,3,4,6-tetra(2-mercaptoethyl)glyurea is more preferred for its even faster reaction rate.

[0065] Because the epoxy resin composition is cured using either the first or second polythiol described above, the curing temperature can be lowered. When curing the epoxy resin composition of this embodiment, a first curing is performed by light irradiation, followed by a second curing by heating, thereby obtaining a cured product. The temperature during light irradiation is preferably 20–40°C. Furthermore, the subsequent heating is preferably performed at 50–100°C. The curing reactions performed by the first and second polythiols are both relatively fast. Therefore, the epoxy resin can be cured at such a low temperature. Thus, the epoxy resin composition of this embodiment can be cured at a low temperature, and therefore, when used as an adhesive for bonding inkjet head components, the deterioration of the component can be suppressed.

[0066] The polythiol content is preferably 60 to 100 parts by weight relative to 100 parts by weight of epoxy resin. More preferably, it is 60 to 75 parts by weight relative to 100 parts by weight of epoxy resin. If the polythiol content is less than 60 parts by weight, the crosslinking density decreases and the solvent resistance deteriorates.

[0067] <Photoalkali-producing agent>

[0068] The epoxy resin composition of this embodiment includes a photoalkali-generating agent. A photoalkali-generating agent is a compound that generates alkali through irradiation with UV light. In the epoxy resin composition of this embodiment, the photoalkali-generating agent is preferably a compound that generates an organic base through irradiation with UV light suitable for alkali generation.

[0069] The epoxy resin composition of this embodiment contains one or more of the above-mentioned photoalkali-generating agents. Furthermore, at least one of these photoalkali-generating agents preferably contains a borate. By including at least one of the photoalkali-generating agents in a borate, the reaction rate during curing can be accelerated. Examples of photoalkali-generating agents include "1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidine n-butyltriphenylborate" and "(Z)-{[bis(dimethylamino)methylene]amino}-N-cyclohexyl(cyclohexylamino)methylimine". "Tetra(3-fluorophenyl)borate", etc. Commercially available products include WPBG-300 (trade name, manufactured by Fujifilm and Koh Genpaku Co., Ltd.) and WPBG-345 (trade name, manufactured by Fujifilm and Koh Genpaku Co., Ltd.).

[0070] The photoalkali-generating agent is preferably contained in the epoxy resin composition at a ratio of 3 to 10 equivalents of epoxy resin. More preferably, it is contained at a ratio of 5 to 10 equivalents of epoxy resin. This accelerates the reaction of the epoxy resin composition and, consequently, increases the thickening rate after UV irradiation. When the content of the photoalkali-generating agent in the epoxy resin is less than 3 equivalents of epoxy resin, the reaction of the epoxy resin composition may slow down. When the content of the photoalkali-generating agent in the epoxy resin exceeds 10 equivalents of epoxy resin, the storage stability of the epoxy resin composition may decrease.

[0071] <Sensitizer>

[0072] The epoxy resin composition of this embodiment contains a sensitizer. Because the epoxy resin composition of this embodiment contains both a photoalkali-generating agent and a sensitizer, it can further promote alkali generation. By including the sensitizer, the photoalkali-generating agent can generate alkali through a shorter period of light irradiation. Furthermore, the photoalkali-generating agent can generate alkali through irradiation with longer wavelengths of light. Photoalkali-generating agents typically exhibit significant absorption around 345 nm, but by adding a sensitizer, the photoalkali-generating agent has the advantage of exhibiting photosensitivity in the longer wavelength region (around 365 nm).

[0073] The sensitizer is not particularly limited, and examples include 1-chloroanthraquinone, 2-ethylanthraquinone, and 2-isopropylthioxanthraquinone. Among these, 2-ethylanthraquinone and 2-isopropylthioxanthraquinone are preferred, and 2-isopropylthioxanthraquinone is more preferred. By adding a sensitizer, the photoalkalizing agent has the advantage of exhibiting photosensitivity in the long wavelength region (around 365 nm).

[0074] The sensitizer is preferably contained in 0.5 to 5 parts by weight of epoxy resin per 100 parts by weight. More preferably, the sensitizer is contained in 1 to 3 parts by weight of epoxy resin per 100 parts by weight.

[0075] <Silane Coupling Agent>

[0076] The epoxy resin composition of this embodiment preferably contains a silane coupling agent. By containing a silane coupling agent, the epoxy resin composition of this embodiment exhibits improved adhesion when used as an adhesive for bonding inkjet head components.

[0077] There are no particular limitations on the silane coupling agent, but compounds having epoxy or amino groups, or isocyanates, are preferred. Examples of compounds having epoxy groups include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane. Examples of compounds having amino groups include N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine. Examples of isocyanates include 3-isocyanatepropyltriethoxysilane. From the viewpoint of improving adhesion, 3-glycidoxypropyltrimethoxysilane is further preferred.

[0078] The silane coupling agent is preferably contained in 0.2 to 10 parts by weight of epoxy resin per 100 parts by weight. More preferably, it is contained in 0.2 to 2 parts by weight of epoxy resin per 100 parts by weight. By keeping the content of the silane coupling agent in the epoxy resin composition within this range, the adhesiveness is improved. If the content of the silane coupling agent exceeds 10 parts by weight, the adhesive strength may decrease due to the aggregation of the silane coupling agent.

[0079] <Other Additives>

[0080] In addition to the components described above, the epoxy resin composition of this embodiment may also contain thixotropic agents / viscosity modifiers, etc.

[0081] <Method for manufacturing epoxy resin composition>

[0082] The method for manufacturing the epoxy resin of this embodiment is not particularly limited, and the components contained in the epoxy resin composition of this embodiment described above can be mixed to manufacture it.

[0083] 2. Cured material

[0084] One embodiment of the cured product of the present invention is the reactant of the epoxy resin composition of this embodiment described above. This reactant is obtained by curing the epoxy resin composition of this embodiment with light, and is the cured product of this embodiment.

[0085] The cured product of this embodiment is a cured product obtained by photocuring the epoxy resin composition of this embodiment, and therefore is a cured product formed at low temperature and in a short time. When the cured product of this embodiment is used to bond the inkjet head components together, it preferably exhibits excellent ink resistance and sealing properties. If the epoxy resin composition of this embodiment is an epoxy resin having three or more epoxy groups in one molecule, its ink resistance and sealing properties are particularly excellent.

[0086] In this embodiment, the nitrogen content in the cured product is preferably 7.5 to 11% by mass, and the sulfur content is preferably 10 to 17% by mass.

[0087] The nitrogen and sulfur content in the cured product of this embodiment can be determined, for example, by the following method. The apparatus can be a fully automated elemental analyzer, the Vario EL cube, manufactured by Elementar. The preferred measurement conditions are CHNS measurement mode, combustion temperature 1150°C, and reduction temperature 850°C. Then, a tin boat is preferably used, the combustion time is set to 150 seconds, and the detector is a thermal conductivity detector (TCD).

[0088] It should be noted that the method for manufacturing the cured product of this embodiment will be described in the following description of the method for manufacturing the joint of this embodiment.

[0089] 3. Joint

[0090] <Joint>

[0091] One embodiment of the joint of the present invention includes the cured product of the present embodiment described above. The joint of this embodiment is preferably formed by joining multiple components together using the epoxy resin composition of this embodiment as an adhesive. Furthermore, the joint of this embodiment is preferably an inkjet head, camera module, etc., joined as described above. In this case, the inkjet head, camera module, etc., has multiple components and a cured product obtained as a reactant from the epoxy resin composition of this embodiment. In addition, an inkjet head is particularly preferred as the joint of this embodiment.

[0092] In this embodiment, the joint is formed by bonding multiple components together using the epoxy resin composition of this embodiment as an adhesive, thus suppressing component displacement. Furthermore, for the same reason, component deterioration in the joint of this embodiment is suppressed. The above-mentioned effects are particularly significant when the multiple components constituting the inkjet head are bonded using the epoxy resin composition of this embodiment as an adhesive. Figure 1 This is a schematic diagram illustrating one embodiment of the joint of the present invention. The joint in this embodiment is an inkjet head 1. The inkjet head 1 of this embodiment includes a base disk 4, a cured epoxy resin composition 5 located on one side of the base disk 4, and a nozzle plate 2 disposed on the side opposite to the side of the cured epoxy resin composition 5 where the base disk 4 is disposed. Nozzle holes 3 are formed on the nozzle plate 2. The base disk 4 and the nozzle plate 2 are joined using the epoxy resin composition of this embodiment as an adhesive. Furthermore, Figure 2 This is a schematic diagram illustrating another embodiment of the bonding body of the present invention. The bonding body in this embodiment is part 1 of a camera module. Part 1 of the camera module in this embodiment includes a base plate 8, a cured epoxy resin composition 9 located on one side of the base plate 8, and a PC chip 7 disposed on the side opposite to the side of the cured epoxy resin composition 9 where the base plate 8 is disposed. The base plate 8 and the PC chip 7 are bonded together using the epoxy resin composition of this embodiment as an adhesive.

[0093] In the assembly of this embodiment, the material of the components is preferably metal, glass, ceramic, resin, etc.

[0094] <Method for manufacturing the joint>

[0095] Next, the method for manufacturing the bonded body of this embodiment will be described. The bonded body of this embodiment is formed by bonding multiple components together using the epoxy resin of this embodiment as an adhesive; therefore, the multiple components are bonded together while the cured material of this embodiment is sandwiched between them. Therefore, the method for manufacturing the bonded body of this embodiment is a method for creating a state in which multiple components are bonded together while sandwiching the cured material of this embodiment, and it includes the method for manufacturing the cured material of this embodiment.

[0096] The joint of this embodiment is a joint having two plate-shaped components, and a cured product of this embodiment bonded together while being held between the two plate-shaped components. This joint is made by bonding the two plate-shaped components using the epoxy resin composition of this embodiment as an adhesive. Hereinafter, a method for making a joint with this structure will be described.

[0097] First, at room temperature, the surface of a plate-shaped component is coated with the epoxy resin composition of this embodiment. The method of coating the epoxy resin composition is not particularly limited.

[0098] Next, the epoxy resin composition coated on the surface of the plate-shaped component is irradiated with UV light for temporary curing. Temporary curing is preferably performed at room temperature. In this specification, room temperature refers to a temperature in the range of 20–30°C. Since UV irradiation during the manufacture of the bond of this embodiment does not require high temperatures, component degradation can be suppressed.

[0099] Here, UV light refers to light containing ultraviolet light, specifically light that produces alkali by irradiating a composition containing a photoalkali-generating agent and a sensitizer. Preferably, the irradiated UV light is capable of effectively producing alkali through the photoalkali-generating agent and sensitizer contained in the epoxy resin composition. As UV light, light with a peak wavelength in the wavelength range of 340–380 nm is preferred, and the cumulative light intensity is preferably 100–200 J / cm². 2 The range.

[0100] Next, one side of another plate-shaped component is laminated onto the surface of the plate-shaped component coated with the epoxy resin composition, resulting in an assembly with a structure in which a UV-cured epoxy resin composition is sandwiched between the two plate-shaped components. Then, the assembly is heated to 50–100°C for final curing to obtain a bond. Furthermore, since the epoxy resin composition sandwiched between the plate-shaped components cures at this time, a cured product can be obtained simultaneously with the bond. Because the epoxy resin composition of this embodiment reacts quickly, final curing can be performed even when heated at a low temperature of 50–100°C. Moreover, the low final curing temperature helps suppress component deterioration. Additionally, because the epoxy resin composition of this embodiment reacts quickly, positional shift can be suppressed when joining the two plate-shaped components.

[0101] Example

[0102] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. It should be noted that, unless otherwise stated, the operation in the following examples is carried out at room temperature (25°C).

[0103] (Examples 1-13, Comparative Examples 1-3)

[0104] (Epoxy resin composition)

[0105] Epoxy resin, polythiol, photoalkali-generating agent, sensitizer, and silane coupling agent were mixed in the combinations shown in Tables 1 and 2 to prepare epoxy resin compositions. The units for the combinations shown in Tables 1 and 2 are parts by mass. In Tables 1 and 2, the "Name" column indicates the trade name or compound name.

[0106] The components were mixed by stirring the epoxy resin, photoalkali-generating agent, and sensitizer, heating at 110°C for 30 minutes, and then adding polythiol after cooling. Then, the mixture was stirred for 1 minute using Awatori Rentaro (model: AR-250) manufactured by Thinky.

[0107] The components contained in the epoxy resin composition are as follows.

[0108] (Epoxy resin)

[0109] jER828 (trade name): Bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 184-194

[0110] jER630 (trade name): Multifunctional epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 90-106

[0111] (Polythiol)

[0112] PE-1 (Karenz MT PE-1; trade name): Ester-type polythiol, manufactured by Resonac, compound name: pentaerythritol tetra(3-mercaptobutyrate).

[0113] DPMP (trade name): Ester-type polythiol, manufactured by Sakai Chemical Industry Co., Ltd.; compound name: 3-mercaptopropionate of dipentaerythritol.

[0114] C3TS-G (trade name): Glycourea-type polythiol, manufactured by Shikoku Chemical Industry Co., Ltd.; compound name: 1,3,4,6-tetra(3-mercaptopropyl)glycourea.

[0115] PEPT: Pentaerythritol tripropanethiol, manufactured by SC Organic Chemicals Co., Ltd.

[0116] (Photo-alkali-producing agent)

[0117] WPBG-300 (trade name): Manufactured by Fujifilm and Koko Pure Chemical Industries Co., Ltd.; compound name: 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidine n-butyltriphenylborate.

[0118] WPBG-345 (trade name): Manufactured by Fujifilm and Koko Pure Chemical Industries, Inc., compound name; (Z)-{[bis(dimethylamino)methylene]amino}-N-cyclohexyl(cyclohexylamino)methylimine Tetra(3-fluorophenyl)borate

[0119] (Sensitizer)

[0120] 2-Isopropylthioxanthone: Manufactured by Fujifilm and Koko Pure Chemical Industries, Inc., compound name: 2-isopropylthioxanthone

[0121] 2-Ethylanthraquinone, manufactured by Tokyo Chemical Industry Co., Ltd., compound name: 2-Ethylanthraquinone

[0122] (Silane coupling agent)

[0123] KBM-403 (trade name): Manufactured by Shin-Etsu Chemical Industry Co., Ltd.; compound name: 3-glycidyl etheroxypropyltrimethoxysilane.

[0124] The obtained epoxy resin compositions (Examples 1-13, Comparative Examples 1-3) were evaluated as follows. The results are shown in Tables 1 and 2.

[0125] (Position offset)

[0126] For epoxy resin compositions with a cumulative light intensity of 182 J / cm 2 The epoxy resin composition was irradiated with ultraviolet (UV) light. The epoxy resin composition gelled under UV irradiation. Then, it was heated to 100°C. The viscosity after the start of heating was measured using a rheometer. The viscosity reduction rate was then calculated using the following formula: The viscosity reduction rate is the value obtained by subtracting the lowest viscosity after the start of heating from the initial viscosity, dividing by the initial viscosity, and then multiplying by 100.

[0127] Viscosity reduction rate = {(initial viscosity - lowest viscosity after heating begins) / initial viscosity} × 100 [%]

[0128] Ultraviolet irradiation was performed at room temperature. Initial viscosity was measured immediately after heating began. Viscosity after heating began was measured once per second.

[0129] The evaluation criteria for viscosity reduction rate are as follows. A and B are acceptable, while C and D are unacceptable.

[0130] A: Less than 5%

[0131] B: 5% or more but less than 10%

[0132] C: 10% or more but less than 20%

[0133] D: Over 20%

[0134] (Low-temperature curing properties)

[0135] The residual heat of combustion of the obtained epoxy resin composition was measured using a differential scanning calorimeter (DSC). The low-temperature curability was determined as the unreacted ratio according to the following formula for calculating the unreacted ratio. The unreacted ratio is the ratio of the amount of unreacted components remaining unreacted when the epoxy resin composition is cured at low temperature to the amount of the epoxy resin composition before curing. The more the low-temperature curing proceeds, the more the reaction proceeds during the 1-hour placement at 100 °C, and thus the smaller the residual heat of combustion. Here, the "heat of combustion before curing" is the heat of combustion generated when the epoxy resin composition before curing is cured. The "heat of combustion of the cured product" is the heat of combustion generated during the 1-hour placement of the epoxy resin composition at 100 °C.

[0136] Unreacted ratio = (1 - (heat of combustion of the cured product / heat of combustion before curing)) × 100 [%]

[0137] The evaluation criteria for low-temperature curability are as follows. A and B are qualified, and C and D are unqualified.

[0138] A: Less than 10%

[0139] B: 10% or more and less than 15%

[0140] C: 15% or more and less than 20%

[0141] D: 20% or more

[0142] The obtained epoxy resin compositions (Examples 1 to 13, Comparative Examples 1 to 3) were irradiated with ultraviolet light (UV) at 23 °C with an accumulated light amount of 182 J / cm 2 . The epoxy resin compositions were gelled by ultraviolet irradiation. Then, they were heated to 100 °C and cured at 100 °C for 1 hour to obtain cured products. The amount of the epoxy resin composition used for curing was 0.2 g each. The obtained cured products were the cured products of the present invention. The swelling ratio of the obtained cured products was determined according to the following method.

[0143] (Swelling ratio)

[0144] The mass of each cured product was measured separately. Then, each cured product was immersed in anisole as a solvent and left at 60 °C for 7 days. After 7 days, each swollen cured product was taken out from the solvent and the mass was measured. The swelling ratio was calculated by the following formula for calculating the swelling ratio.

[0145] Swelling ratio = {(mass of the swollen cured product - mass of the cured product before swelling) / mass of the cured product before swelling} × 100 [%]

[0146] The evaluation criteria for the swelling ratio are as follows. A and B are qualified, and C and D are unqualified.

[0147] A: Less than 5%

[0148] B: 5% or more but less than 10%

[0149] C: 10% or more but less than 20%

[0150] D: Over 20%

[0151] Using the obtained epoxy resin composition as an adhesive, two components are joined to form a bonded body. As components, plate-shaped glass and sheet-shaped polyimide are used. The resulting bonded body is a structure obtained by clamping the cured product, which is a reactant of the epoxy resin composition, and joining the plate-shaped glass and sheet-shaped polyimide. The resulting bonded body is the bonded body of the present invention.

[0152]

[0153]

[0154] Based on the evaluation results of Examples 3 and 4, as well as Examples 9, 10 and 11, it can be seen that increasing the amount of photoalkali-producing agent further improves the suppression effect of position shift.

[0155] Based on the evaluation results of Example 8 and Comparative Example 1, it can be seen that, as a polythiol, the glycourea-based type showed better evaluation results in terms of positional displacement, ink resistance, and low-temperature curing properties compared to the ether-based type. This can be attributed to the fact that the epoxy resin composition of Comparative Example 1 is a combination of a difunctional epoxy resin and an ether-based thiol, and the reaction temperature of 100°C was too low, leaving unreacted components.

[0156] The epoxy resin composition of Comparative Example 2 is a combination of a trifunctional epoxy resin and an ether-based thiol. The reaction temperature of 100°C was too low, leaving unreacted components. Therefore, the evaluation results for positional displacement and low-temperature curing properties deteriorated. Furthermore, the epoxy resin composition of Comparative Example 3 is a combination of a difunctional epoxy resin and a tetrafunctional ester-type thiol. Its low crosslinking density resulted in a poorer evaluation of ink resistance.

[0157] The epoxy resin composition of Example 3 was obtained by adding 2 parts by weight of a silane coupling agent to the epoxy resin composition of Example 2. The epoxy resin composition of Example 3 exhibited stronger adhesion than the epoxy resin composition of Example 2. This demonstrates that the adhesion was further improved by the silane coupling agent. The adhesion was confirmed by the following method: First, a polyimide film was bonded to a sheet of glass using the epoxy resin composition to create a bond. Then, the adhesion was confirmed by a 90-degree peel test (JISK6854-1) on the resulting bond.

[0158] The nitrogen and sulfur contents of the cured epoxy resin composition of Example 10 were determined, and the nitrogen content was 8.2% by mass and the sulfur content was 11.3% by mass. The nitrogen and sulfur contents in the cured product were determined by the following method. An Elementar Vario EL Cube fully automated elemental analyzer was used as the measuring apparatus. The measuring conditions were set to: CHNS measurement mode, combustion temperature 1150°C, and reduction temperature 850°C. Then, a tin boat was used, the combustion time was set to 150 seconds, and the detector was a thermal conductivity detector (TCD).

[0159] Industrial availability

[0160] According to the present invention, an epoxy resin composition can be provided that, when used as an adhesive for bonding components of an inkjet head to each other, can suppress positional misalignment of the components and suppress thermal degradation of the components.

Claims

1. An epoxy resin composition, characterized in that, It contains epoxy resin, polythiol, photoalkali-generating agent, and sensitizer, and, It contains one or more of the aforementioned epoxy resins. At least one of the epoxy resins has two or more epoxy groups in one molecule. The polythiol contains an ester bond and has more than 5 thiol groups, or the polythiol contains a nitrogen atom and the thiol groups are bonded to the nitrogen atom via an alkylene group.

2. The epoxy resin composition according to claim 1, characterized in that, The polythiol, in which the thiol group is bonded to the nitrogen atom via an alkylene group, has a glycourea backbone.

3. The epoxy resin composition according to claim 1, characterized in that, At least one of the epoxy resins has three or more epoxy groups in its molecule.

4. The epoxy resin composition according to claim 1, characterized in that, The epoxy resin is a glycidylamine-based resin.

5. The epoxy resin composition according to claim 1, characterized in that, It contains one or more of the aforementioned photoalkali-producing agents. At least one of the photoalkali-producing agents contains a borate.

6. The epoxy resin composition according to claim 1, characterized in that, The content of the photoalkali-generating agent is 3 to 10 equivalents relative to 100 equivalents of epoxy resin.

7. The epoxy resin composition according to claim 1, wherein, It contains one or more of the aforementioned sensitizers. At least one of the sensitizers is 2-isopropylthioxanthone or 2-ethylanthraquinone.

8. The epoxy resin composition according to claim 1, wherein, It contains silane coupling agents.

9. The epoxy resin composition according to claim 8, wherein, The silane coupling agent is a compound having an epoxy or amine group, or an isocyanate.

10. A cured product, which is a reactant of the epoxy resin composition according to any one of claims 1 to 9.

11. The cured product according to claim 10, wherein, The nitrogen content is 7.5–11% by mass, and the sulfur content is 10–17% by mass.

12. A joint, characterized in that, It includes the cured product as described in claim 10.

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