Thermosetting resin composition, sealant for display devices, and display device

Abstract

The present invention pertains to a thermosetting resin composition which contains a thermosetting agent (B) and a compound (A) having a backbone represented by general formula (1) and having two or more functional groups that are at least one of glycidyl groups and oxetanyl groups. The thermosetting resin composition has a viscosity of 20.0 Pa·s or less as measured at 25°C and 2.5 rpm using an E-type viscosity system. (In general formula (1), a represents an integer of 0-8, b represents an integer of 0-3, c represents an integer of 0-8, d represents an integer of 0-8, at least one of a, b, and c is 1 or more, n represents an integer of 1 or more, and * represents a position of a bond.)

Description

Thermosetting resin composition, sealant for display device, and display device

[0001] The present invention relates to a thermosetting resin composition, a sealant for a display device, and a display device.

[0002] 2. Description of the Related Art In recent years, liquid crystal display devices, organic EL display devices, electrophoretic display devices, and the like have been put to practical use as display devices for various electronic devices.

[0003] For example, a liquid crystal display device has two transparent substrates with electrodes on their surfaces, a frame-shaped sealant sandwiched between them, and a liquid crystal material sealed within the area surrounded by the sealant. Patent Document 1, for example, discloses a thermosetting resin composition (liquid crystal sealant) containing an epoxy resin and an epoxy resin curing agent as a sealant for sealing the liquid crystal.

[0004] On the other hand, as an electrophoretic display device, a display device having a microcup structure has been proposed, as in Patent Document 2. In the electrophoretic display device, a display element is disposed between a pair of substrates and is sealed by applying a sealant.

[0005] For such electrophoretic display devices, for example, Patent Document 3 describes that a sealant containing epoxy resin or the like can be used.

[0006] JP 2005-018022 A JP 2004-536332 A JP 2014-142549 A

[0007] As described above, sealants used in various display devices are known. A cured product of a thermosetting resin composition contained in the sealant is required to have high flexibility so as to relieve stress when external stress is applied to the display device. If the flexibility of the cured product is low, for example, when attaching the display device to a tablet terminal or the like, the sealant cannot relieve stress applied to the display device, resulting in a problem of peeling off from the substrate.

[0008] According to the inventors' investigations, the sealants containing the thermosetting resin compositions described in Patent Documents 1 and 3 do not increase the flexibility of the cured product, and peeling of the sealant cannot be prevented when stress is applied to the display device.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a thermosetting resin composition, a sealant for a display device, and a display device that can suppress peeling of the sealant from the substrate when stress is applied to the display device.

[0010] The present invention relates to the following thermosetting resin composition, sealant for a display device, and display device.

[0011] The thermosetting resin composition of the present invention contains a compound (A) having a structure represented by general formula (1) and having two or more functional groups, at least one of glycidyl groups and oxetanyl groups, in total, and a thermosetting agent (B), and has a viscosity of 20.0 Pa s or less as measured with an E-type viscometer at 25°C and 2.5 rpm.

[0012] In general formula (1), a represents an integer of 0 to 8, b represents an integer of 0 to 3, c represents an integer of 0 to 8, and d represents an integer of 0 to 8, and at least one of a, b, and c is 1 or greater, n is an integer of 1 or greater, and * represents a bonding position. When compound (A) has a plurality of structures represented by general formula (1), the numbers of a, b, c, d, and n in each structure may be the same or different.

[0013] The sealant for a display device of the present invention contains the above-mentioned thermosetting resin composition.

[0014] The display device of the present invention comprises a protective member, a substrate having an image display section, and the above-described sealant for a display device disposed between the protective member and the substrate.

[0015] According to the present invention, it is possible to provide a thermosetting resin composition that can suppress peeling of a sealant from a substrate when stress is applied to a display device, a sealant containing the same, and a display device.

[0016] FIG. 1 is a schematic diagram showing the configuration of a display device according to one embodiment of the present invention.

[0017] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0018] 1. Thermosetting Resin Composition The thermosetting resin composition of the present invention contains a compound (A) having a structure represented by general formula (1) and having two or more functional groups, at least one of glycidyl groups and oxetanyl groups, in total, and a thermosetting agent (B), and has a viscosity of 20.0 Pa s or less as measured with an E-type viscometer at 25°C and 2.5 rpm.

[0019] In general formula (1), a represents an integer of 0 or more and 8 or less, b represents an integer of 0 or more and 3 or less, c represents an integer of 0 or more and 8 or less, and d represents an integer of 0 or more and 8 or less, at least one of a, b, and c is 1 or more, n is an integer of 1 or more, and * represents a bonding position.

[0020] As described above, conventional sealants containing thermosetting resin compositions do not provide high flexibility in the cured product, and there is a problem that the sealant peels off from the substrate when stress is applied to the display device.

[0021] In response to this, the present inventors have conducted extensive research and found that the above-mentioned peeling can be made less likely to occur by incorporating into a thermosetting resin composition a compound (A) which is a compound having a total of two or more functional groups selected from at least one of glycidyl groups and oxetanyl groups and which has a structure represented by the above general formula (1). The reason for this is unclear, but it is thought to be as follows.

[0022] The structure represented by the general formula (1) is believed to be a flexible structure capable of enhancing molecular mobility. Therefore, it is believed that the inclusion of compound (A) having this structure in a thermosetting resin composition increases the flexibility of the cured product. Furthermore, a cured product of a thermosetting resin composition can be obtained by crosslinking the compounds contained in the composition in the presence of a thermosetting agent. In this case, since the compound has a skeleton represented by the general formula (1), the distance between crosslinking points between the compounds can be increased, thereby lowering the crosslink density. This is also believed to increase the flexibility of the cured product. Furthermore, by increasing the flexibility of the cured product, even if stress that would cause the sealant to peel is applied to the display device, the stress can be dispersed and alleviated throughout the cured product, thereby preventing peeling of the sealant.

[0023] 1-1. Compound (A) The compound (A) in the present invention has a total of two or more functional groups selected from at least one of glycidyl groups and oxetanyl groups, and has a structure represented by the above general formula (1).

[0024] The compound (A) may be any compound having two or more functional groups selected from at least one of glycidyl groups and oxetanyl groups, but preferably has two or more glycidyl groups. Specifically, the compound (A) is preferably a polyfunctional epoxy compound.

[0025] The total number of glycidyl groups and oxetanyl groups contained in one molecule of compound (A) may be two or more, but from the viewpoint of preventing a decrease in flexibility of the cured product due to an increase in crosslink density, it is preferable that the number is two.

[0026] In the above general formula (1), a represents an integer of 0 to 8, b represents an integer of 0 to 3, c represents an integer of 0 to 8, and d represents an integer of 0 to 8, wherein at least one of a, b, and d is 1 or greater, and n is an integer of 1 or greater. Of these, in the above general formula (1), the value of a+b+c+d of compound (A) is preferably 1 to 10, more preferably 2 to 5. The greater the number of carbon atoms in the structure represented by general formula (1), the greater the number of crosslinking points and the greater the flexibility of the cured product. Meanwhile, by reducing the number of carbon atoms in the structure represented by general formula (1), the decrease in moisture resistance of the cured product due to an increase in the distance between crosslinking points can be suppressed, and the viscosity of the composition can be easily adjusted to an appropriate range by suppressing an increase in the molecular weight of compound (A). More specifically, it is preferable that (a=3, b=0, c=0, d=0), (a=1, b=1, c=0, d=0), or (a=0, b=1, c=0, d=1) is satisfied, and it is more preferable that (a=3, b=0, c=0, d=0) is satisfied. Furthermore, it is preferable that compound (A) is a bifunctional epoxy compound that satisfies these conditions.

[0027] In the general formula (1), n ​​is an integer of 1 or more, preferably 1 to 10, more preferably 3 to 7, and even more preferably 3 to 5. When n is 10 or less, the molecular weight of compound (A) can be appropriately adjusted, making it easier to adjust the viscosity of the thermosetting resin composition within the above range. Furthermore, when n is 5 or less, it is easier to maintain the moisture resistance of the cured product.

[0028] Compound (A) may have only one structure represented by general formula (1) in its skeleton, or may have multiple structures represented by general formula (1) in its skeleton, each having the same or different values ​​of a, b, c, d, and n. Furthermore, multiple structures represented by general formula (1) with different values ​​of a, b, c, and d may be consecutive. When compound (A) has structures represented by general formula (1) at multiple positions, the numbers of a, b, c, d, and n in each structure may be the same or different.

[0029] Furthermore, compound (A) may further have a structure other than the structure represented by general formula (1). Examples of the other structure include a structure represented by the following general formula (2) and a structure represented by general formula (3). Of these, the structure represented by the following general formula (2) is preferred from the viewpoint of further improving the moisture resistance of the cured product.

[0030]

[0031]

[0032] In general formula (2) and general formula (3), R １ is a single bond, an alkylene group having from 1 to 4 carbon atoms, an alkylidene group having from 2 to 4 carbon atoms, a sulfonyl group, an oxygen atom, or a sulfur atom; R ２ represents a hydrogen atom or an alkylene group having 1 to 4 carbon atoms, m represents an integer of 1 to 4, and * represents a bonding position.

[0033] According to the findings of the present inventors, in conventional sealants, when a thermosetting resin composition contains a compound having a structure represented by general formula (2), moisture resistance can be improved, but the flexibility of the cured product cannot be improved, and peeling of the sealant cannot be suppressed when stress is applied to a display device. On the other hand, even when compound (A) contained in the thermosetting resin composition of the present invention contains a structure represented by general formula (2) to improve moisture resistance, it has the structure represented by general formula (1) above, so that the flexibility of the cured product can be increased and peeling of the sealant can be suppressed when stress is applied to a display device.

[0034] In general formula (2), R １ is preferably an alkylene group having 1 to 4 carbon atoms, or an alkylidene group having 2 to 4 carbon atoms, and more preferably an alkylidene group having 2 to 4 carbon atoms.

[0035] Examples of the alkylene group having 1 to 4 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, and an isobutylene group.

[0036] Examples of the alkylidene group having from 2 to 4 carbon atoms include a methylidene group, an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, etc. Of these, an isopropylidene group is preferred.

[0037] In general formula (2), R ２ is a hydrogen atom or an alkylene group having 1 to 4 carbon atoms, and m is an integer of 1 to 4. ２ may be the same or different, but are preferably all hydrogen atoms. Also, m is preferably 1.

[0038] R ２ When is an alkylene group having 1 to 4 carbon atoms, it is preferable that the number of carbon atoms is 2 to 4.

[0039] The compound (A) may have only one structure represented by general formula (2), or may have one or more structures represented by R １ and R ２ When compound (A) has a structure represented by general formula (2) at a plurality of positions, R １ and R ２ may be the same or different.

[0040] In general formula (2), R １ is a single bond, the general formula (2) has a biphenyl structure. In this case, in this specification, a compound having a structure represented by the general formula (1) and a biphenyl structure, which has two or more functional groups selected from at least one of glycidyl groups and oxetanyl groups, is referred to as compound (A).

[0041] In general formula (3), R １ , R ２ , and m can be the same as in general formula (2), and therefore detailed explanations will be omitted.

[0042] The compound (A) may be solid at room temperature, but is preferably liquid from the viewpoint of making it easier to adjust the viscosity of the thermosetting resin composition to the above range.

[0043] When compound (A) is an epoxy compound, the epoxy equivalent of compound (A) is preferably 300 g / eq or more, more preferably 350 g / eq or more, more preferably 350 g / eq or more but 750 g / eq or less, and even more preferably 350 g / eq or more but 500 g / eq or less. When the epoxy equivalent is 300 g / eq or more, the flexibility of the cured product can be further improved. Furthermore, when the epoxy equivalent is 750 g / eq or less, moisture resistance can be more easily maintained. The epoxy equivalent can be measured by a method in accordance with JIS K7236:2009.

[0044] The compound (A) preferably has a glass transition temperature (Tg) of 100° C. or lower, more preferably 80° C. or lower, and even more preferably 70° C. or lower, of a cured product obtained by the following method. When the glass transition temperature is 100° C. or lower, the flexibility of the cured product can be further increased. The lower limit of the glass transition temperature is not particularly limited, but is, for example, 0° C. or higher.

[0045] The cured product of the compound (A) can be obtained by mixing 100 parts by mass of the compound (A), methylhexahydrophthalic anhydride in a chemical equivalent amount relative to 100 parts by mass of the compound (A), and 1 part by mass of dimethylbenzylamine, and heating the mixture at 110°C for 3 hours and then at 165°C for 2 hours.

[0046] The glass transition temperature can be measured, for example, using a dynamic mechanical analysis (DMA) device (DMS7100, manufactured by Hitachi High-Tech Science Corporation).

[0047] Examples of commercially available products of the compound (A) include EP-4010S and EP-4010L (both manufactured by ADEKA Corporation). The thermosetting resin composition may contain only one type of compound (A), or may contain two or more types of compound (A).

[0048] The content of compound (A) is preferably 1.5% by mass or more and 20% by mass or less, and more preferably 2.5% by mass or more and 15% by mass or less, relative to the total mass of the thermosetting resin composition. When the content is 1.5% by mass or more, the flexibility of the thermosetting resin composition can be further improved. This can further prevent the sealant from peeling off from the substrate even when stress is applied to the display device. Furthermore, when the content is 20% by mass or less, the viscosity of the thermosetting resin composition can be easily adjusted within the above range.

[0049] 1-2. Compound (a) Having a Biphenyl Structure The thermosetting resin composition of the present invention may further contain a compound (a) having at least one functional group selected from a glycidyl group and an oxetanyl group and a biphenyl structure. When the thermosetting resin composition contains compound (a), the biphenyl structure of compound (a) can further enhance the moisture resistance of the thermosetting resin composition. Furthermore, when compound (a) is contained, the viscosity of the thermosetting resin composition can be further reduced, making it easier to adjust the viscosity within the above range.

[0050] According to the findings of the present inventors, in conventional sealants, when a compound (a) having a biphenyl structure is added to a thermosetting resin composition, moisture resistance can be improved, but the flexibility of the cured product cannot be improved, and peeling of the sealant cannot be suppressed when stress is applied to a display device. On the other hand, even when the compound (A) contained in the thermosetting resin composition of the present invention contains the compound (a) having a biphenyl structure to improve moisture resistance, the compound (A) has a structure represented by the above general formula (1), and therefore the flexibility of the cured product can be increased and peeling of the sealant can be suppressed when stress is applied to a display device.

[0051] As described above, in this specification, a compound having at least one functional group selected from a glycidyl group and an oxetanyl group, a biphenyl structure, and a structure represented by general formula (1) is referred to as compound (A). That is, compound (a) does not include a compound having a structure represented by general formula (1).

[0052] The compound (a) may be any compound having at least one functional group selected from the group consisting of a glycidyl group and an oxetanyl group, and a biphenyl structure, but it is preferable that the compound (a) has a glycidyl group among the functional groups. Specifically, the compound (a) is preferably an epoxy compound having a biphenyl structure.

[0053] The number of glycidyl groups and oxetanyl groups contained in one molecule of the compound (a) is preferably one.

[0054] The compound (a) may be solid at room temperature, but is preferably liquid from the viewpoint of making it easier to adjust the viscosity of the thermosetting resin composition to the above range.

[0055] When compound (a) is an epoxy compound, the epoxy equivalent of compound (a) is preferably 226 g / eq or more and 260 g / eq or less. When the epoxy equivalent is 226 g / eq or more, the flexibility of the cured product can be further increased. Furthermore, when the epoxy equivalent is 260 g / eq or less, the decrease in moisture resistance can be further suppressed. The epoxy equivalent can be measured by the same method as described for compound (A).

[0056] Specific examples of the compound (a) include o-phenylphenol glycidyl ether, m-phenylphenol glycidyl ether, p-phenylphenol glycidyl ether, and derivatives thereof. The thermosetting resin composition of the present application may contain only one type of compound (a), or may contain two or more types of compound (a).

[0057] Examples of commercially available products of compound (a) include OPP-EP (manufactured by Yokkaichi Synthetic Co., Ltd.).

[0058] The content of compound (a) is preferably 10% by mass or more and 30% by mass or less, and more preferably 15% by mass or more and 25% by mass or less, based on the total mass of the thermosetting resin composition. When the content is 10% by mass or more, the moisture resistance of the thermosetting resin composition can be further improved. Furthermore, when the content is 30% by mass or less, the flexibility of the cured product can be further maintained.

[0059] The compound (a) may partially contain a functional group other than a glycidyl group and an oxetanyl group, and a structure other than a biphenyl structure.

[0060] 1-3. Other Compounds The thermosetting resin composition of the present invention may contain other curable compounds that do not correspond to compound (A) and compound (a). Examples of other curable compounds include polyfunctional epoxy compounds that do not have the structure represented by general formula (1) or a biphenyl structure.

[0061] The total content of the other curable compounds is preferably 30% by mass or more and 40% by mass or less, based on the total mass of the thermosetting resin composition. When the content is in the above range, it is possible to easily adjust the viscosity of the thermosetting resin composition to the above range.

[0062] 1-4. Heat Curing Agent (B) The thermosetting resin composition of the present invention contains a heat curing agent (B).

[0063] The heat curing agent (B) may be any agent capable of reacting with compounds contained in the thermosetting resin composition, such as the compound (A), to cure the composition, and may be, for example, a dihydrazide-based heat curing agent, an amine adduct-based heat curing agent, or a polyamine-based heat curing agent. Of these, polyamine-based heat curing agents are preferred from the viewpoint of enhancing the viscosity stability of the thermosetting resin composition.

[0064] The heat curing agent (B) is preferably a latent heat curing agent, which is a curing agent that does not cure compounds such as the compound (A) under normal storage conditions (room temperature) but cures these compounds when heat is applied.

[0065] Examples of the latent heat curing agent include dihydrazide-based latent heat curing agents, amine adduct-based latent heat curing agents, polyamine-based latent heat curing agents, etc. Among these, polyamine-based latent heat curing agents are preferred from the viewpoint of improving the viscosity stability of the thermosetting resin composition.

[0066] Examples of dihydrazide-based latent heat curing agents include adipic acid dihydrazide (melting point 181°C), 1,3-bis(hydrazinocarboethyl)-5-isopropylhydantoin (melting point 120°C), 7,11-octadecadiene-1,18-dicarbohydrazide (melting point 160°C), dodecanedioic acid dihydrazide (melting point 190°C), and sebacic acid dihydrazide (melting point 189°C).

[0067] Amine adduct latent heat curing agents are latent heat curing agents consisting of an addition compound obtained by reacting a catalytically active amine compound with an arbitrary compound. Examples of amine adduct latent heat curing agents include Amicure PN-40 (melting point 110°C), Amicure PN-50 (melting point 120°C), Amicure PN-23 (melting point 100°C), Amicure PN-31 (melting point 115°C), Amicure PN-H (melting point 115°C), Amicure MY-24 (melting point 120°C), and Amicure MY-H (melting point 131°C) (all manufactured by Ajinomoto Fine-Techno Co., Inc.).

[0068] Examples of polyamine-based latent heat curing agents include ADEKA HARDNER EH5015S (melting point: 85°C to 105°C), ADEKA HARDNER EH4357S (melting point: 75°C to 85°C), and EH5030S (melting point: 70°C to 80°C) (all manufactured by ADEKA Corporation).

[0069] The melting point of the heat curing agent is preferably 60°C or higher and 190°C or lower, more preferably 60°C or higher and 110°C or lower, and even more preferably 65°C or higher and 100°C or lower. When the melting point is 60°C or higher, it is possible to prevent the heat curing agent (B) from reacting with the compound (A) or the like at room temperature and curing the compound. When the melting point is 110°C or lower, it is possible to cure the compound (A) or the like without excessive heating.

[0070] The content of the thermosetting agent (B) is preferably 25% by mass or more and 40% by mass or less, and more preferably 30% by mass or more and 35% by mass or less, relative to the total mass of the thermosetting resin composition. When the content is 25% by mass or more, the curing property of the cured product can be further enhanced. This allows, for example, a cured product of a sealant containing the thermosetting resin composition to adequately seal a display device. Furthermore, when the content is 40% by mass or less, the viscosity of the thermosetting resin composition can be easily adjusted to the above range.

[0071] 1-5. Inorganic Filler (C) The thermosetting resin composition of the present invention may contain an inorganic filler (C). When the thermosetting resin composition contains the inorganic filler (C), the moisture resistance of the cured product tends to be further improved.

[0072] Examples of the inorganic filler (C) include calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, aluminum oxide (alumina), zinc oxide, silicon dioxide, potassium titanate, kaolin, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, silicon nitride, etc. The thermosetting resin composition may contain only one type of inorganic filler (C), or may contain two or more types.

[0073] The shape of the inorganic filler (C) may be regular, such as spherical, plate-like, or needle-like, or may be irregular. When the inorganic filler (C) is spherical, the average primary particle size of the inorganic filler (C) is preferably 0.1 μm or more and 20 μm or less, more preferably 0.1 μm or more and 10 μm or less, and even more preferably 0.5 μm or more and 5.0 μm or less. When the average primary particle size is within the above range, the viscosity of the thermosetting resin composition can be more easily adjusted. The average primary particle size of the inorganic filler (C) can be measured by a laser diffraction method in accordance with JIS Z8825-1:2013.

[0074] Mass average particle diameter d of inorganic filler (C) ５０ The mass average particle diameter d is preferably 0.05 μm or more and 5.0 μm or less, and more preferably less than 25.0 μm. ５０When the mass average particle diameter d of the filler is in the above range, the viscosity stability of the thermosetting resin composition is improved. ５０ is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more, and may be more than 1.0 μm. ５０ is determined by a laser diffraction method in accordance with JIS Z8825-1:2013. Specifically, the particle size indicated by the 50% mass value on the mass accumulation curve obtained by the above measurement is referred to as the mass average particle size d ５０ It can be said that:

[0075] The content of the inorganic filler (C) is preferably 0% by mass or more and 10% by mass or less, and more preferably 0% by mass or more and 5% by mass or less, relative to the total mass of the thermosetting resin composition. When the content is 10% by mass or less, the viscosity of the thermosetting resin composition is prevented from being excessively increased, making it easier to adjust the viscosity.

[0076] 1-6. Others The thermosetting resin composition of the present invention may contain additives such as a silane coupling agent, a rubber agent, an ion trapping agent, an ion exchange agent, a leveling agent, a pigment, a dye, a plasticizer, an antifoaming agent, etc. The thermosetting resin composition may contain only one type of additive, or may contain two or more types of additives.

[0077] Examples of the silane coupling agent include vinyltrimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane.

[0078] The content of the silane coupling agent is preferably 0.01% by mass or more and 5.0% by mass or less, based on the total mass of the thermosetting resin composition. When the content of the silane coupling agent is within the above range, the adhesive strength between the cured product and the substrate can be further increased.

[0079] 1-7. Method for Preparing Thermosetting Resin Composition The method for preparing the above-mentioned thermosetting resin composition is not particularly limited, and the composition can be prepared by mixing the components using a known method. The method for mixing the components is not particularly limited, and for example, a double-arm mixer, a roll mixer, a twin-screw extruder, a ball mill mixer, a planetary mixer, or the like can be used. After mixing the components, the mixture may be filtered to remove impurities, thereby obtaining a thermosetting resin composition, or may be further subjected to a vacuum degassing treatment.

[0080] 1-8. Physical Properties of Thermosetting Resin Composition The thermosetting resin composition of the present invention has a viscosity of 20.0 Pa·s or less, preferably 10.0 Pa·s or less, and more preferably 5.0 Pa·s or less, as measured at 25°C and 2.5 rpm using an E-type viscometer. When the viscosity is 20.0 Pa·s or less, when various display devices are produced using a sealant containing the thermosetting resin composition, the composition can penetrate into minute gaps and more reliably seal the display device. The lower limit of the viscosity is not particularly limited, but is preferably 0.5 Pa·s or more. The viscosity of the thermosetting resin composition can be adjusted to the above range by adjusting the composition of the thermosetting resin composition.

[0081] 2. Sealant for Display Device The sealant for a display device of the present invention (hereinafter simply referred to as "sealant") contains the above-mentioned thermosetting resin composition.

[0082] The sealing agent may be the above-mentioned thermosetting resin composition as it is, or may be a mixture of the above-mentioned thermosetting resin composition and additives.

[0083] The sealant of the present invention can be used in various display devices. In particular, in a display device having a pair of substrates and a display element disposed between the pair of substrates, the sealant is preferably used in such a manner that the cured product of the sealant seals the display element. Specifically, in various display devices having a liquid crystal element, an EL element, an LED element, an electrophoretic display element, an electrochromic display element, or the like, the sealant is preferably used to seal the display element.

[0084] Since the viscosity of the sealant is within the above range, it can easily penetrate into the gaps between the substrates sandwiching the display element, thereby enabling more reliable sealing. In display devices having electrophoretic display elements and electrochromic display elements, it is preferable for the sealant to penetrate into minute gaps, so the sealant of the present invention can be more suitably used for electrophoretic display devices or electrochromic display devices. Examples of electrophoretic display devices and electrochromic display devices include displays and electronic paper that use these methods.

[0085] The sealant can seal the display element by, for example, applying it to the substrate and curing it. The method for applying the sealant is not particularly limited, and known methods such as using a dispenser or screen printing can be used. Alternatively, the sealant may be filled between the pair of substrates that sandwich the display element and then cured. An example of a method for filling the sealant between the substrates is filling it with a dispenser.

[0086] The sealant can be cured by heat curing. The heat curing temperature is preferably 60° C. or higher and 80° C. or lower from the viewpoint of suppressing deterioration of the display device. The heat curing time can be appropriately adjusted depending on the heat curing temperature and the amount of sealant, and is, for example, 30 minutes or higher and 90 minutes or lower.

[0087] 3. Display Device The display device of the present invention includes a pair of substrates, a cured product of the sealant for a display device disposed between the pair of substrates, and a display element disposed in a space surrounded by the cured product of the sealant between the pair of substrates.

[0088] Examples of the substrate include an inorganic substrate and a resin substrate.

[0089] Examples of inorganic substrates include glass substrates, etc. Examples of resin substrates include substrates made of resins such as polyethylene terephthalate, polymethyl methacrylate, polycarbonate, cyclic polyolefin (COC), polypropylene, polystyrene, polyvinyl chloride, transparent ABS resin, transparent nylon, transparent polyimide, and polyvinyl alcohol.

[0090] As described above, examples of the display element include a liquid crystal element, an EL element, an LED element, an electrophoretic display element, an electrochromic display element, and the like.

[0091] For example, a display device having an electrophoretic display element can be configured as shown in FIG.

[0092] The display device 100 has a pair of substrates 110, a cured product 120 of a sealant 1 for a display device arranged between the pair of substrates 110, and a display element 130 arranged in the space surrounded by the cured product 120 of the sealant between the pair of substrates 110.

[0093] The display element 130 has a display layer 130a and a transparent electrode 130b for driving the display layer 130a.

[0094] The display layer 130a may be configured to include charged particles such as pigments and a dispersion medium, for example, microcapsules containing charged particles and a dispersion medium such as an alcohol-based solvent.

[0095] The transparent electrode 130b applies a voltage to the display layer 130a to drive the display layer 130a. A protective film may be provided on the surface of the transparent electrode 130b.

[0096] The display device of the present invention can be manufactured, for example, through the steps of: (1) forming a laminate having a display element and a pair of substrates sandwiching the display element; (2) filling the gap between the pair of substrates formed at the periphery of the laminate with the above-mentioned sealant; and (3) hardening the above-mentioned sealant.

[0097] The method for filling the sealant is not particularly limited, but it can be done using a dispenser, for example. The method for curing the sealant can be the same as the method described for the sealant.

[0098] The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to the descriptions in the examples.

[0099] 1. Materials for thermosetting resin composition 1-1. Compound (A) EP-4010S (manufactured by ADEKA Corporation, bisphenol A type bifunctional epoxy compound (propylene oxide modified)), in general formula (1), a = 3, b = 0, c = 0, R in general formula (2) １ isopropylidene group, epoxy equivalent: 350 g / eq, glass transition temperature of the cured product Tg: 60°C) was used.

[0100] 1-2. Compound (a) Having a Biphenyl Structure OPP-EP (manufactured by Yokkaichi Synthetic Co., Ltd., epoxy compound, epoxy equivalent: 230 g / eq) was used.

[0101] 1-3. Other Compounds (A') Any of the following polyfunctional epoxy compounds was used: EXA-835LV (A'-1) (manufactured by DIC Corporation, bisphenol F / bisphenol A bifunctional epoxy compound, epoxy equivalent: 165 g / eq) YL-983U (A'-2) (manufactured by Mitsubishi Chemical Corporation, bisphenol F bifunctional epoxy compound, epoxy equivalent: 170 g / eq) YL-980 (A'-3) (manufactured by Mitsubishi Chemical Corporation, bisphenol A bifunctional epoxy compound, epoxy equivalent: 190 g / eq) YX8000D (A'-4) (manufactured by Mitsubishi Chemical Corporation, hydrogenated bisphenol A bifunctional epoxy compound, epoxy equivalent: 205 g / eq)

[0102] The glass transition temperature of the compound (A) after curing was measured by the following method.

[0103] 100 parts by mass of the above epoxy compound (compound (A)), methylhexahydrophthalic anhydride in an amount equivalent to the chemical amount of 100 parts by mass of the epoxy compound, and 1 part by mass of dimethylbenzyldiamine were mixed, and the mixture was heated at 110° C. for 3 hours and then at 165° C. for 2 hours. The resulting cured product was processed into a 100 μm film, and the glass transition temperature (Tg) of the cured product was measured by dynamic mechanical analysis (DMA).

[0104] 1-4. Heat Curing Agent (B) EH5030S (a polyamine-based heat curing agent, manufactured by ADEKA Corporation, melting point: 70 to 80°C, amine equivalent: 105 g / equivalent) was used.

[0105] 1-5. Inorganic filler (C) S-100 (silica particles, manufactured by Nippon Shokubai Co., Ltd.) was used.

[0106] 1-6. Others The following were used: Silane coupling agent: KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0107] 2. Preparation of Thermosetting Resin Composition (Example 1) 50 parts by mass of compound (A), 215 parts by mass of compound (a) having a biphenyl structure, 320 parts by mass of polyfunctional epoxy compound (A'-1), 330 parts by mass of thermosetting agent (B), and 30 parts by mass of silane coupling agent were mixed using a triple roll to obtain a thermosetting resin composition. In this example, this was used as a sealant.

[0108] Examples 2 to 7, Comparative Examples 1 to 4 Thermosetting resin compositions were prepared in the same manner as in Example 1, except that the compositions were changed to those shown in Tables 1 and 2.

[0109] 3. Evaluation The obtained thermosetting resin compositions and their cured products were evaluated as follows.

[0110] (Viscosity) The viscosity of the thermosetting resin composition was measured at 25° C. using an E-type viscometer at a rotation speed of 2.5 rpm.

[0111] (Adhesion (Flexibility)) The prepared thermosetting resin composition was dropped onto a screen plate having a mesh diameter of 1.5 mm. The screen plate was then placed so that the mesh portion overlapped the center of a 25 mm × 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC Corporation) on which a transparent electrode had been previously formed, and the thermosetting resin composition was applied from the mesh portion using a squeegee.

[0112] Next, the glass substrate on which the thermosetting resin composition was formed and a mating glass substrate were bonded together from directly above the thermosetting resin composition so that the long sides of the substrates were perpendicular to each other. The bonded two glass substrates were then heated at 80°C for 1 hour to cure the thermosetting resin composition, thereby obtaining a test piece.

[0113] In the obtained test piece, a portion 22.5 mm from the center of the circularly cured thermosetting resin composition was pressed perpendicularly into the glass substrate at a speed of 37.5 mm / min using an indentation tester (Model 210, manufactured by Intesco Corporation), and the stress at which the thermosetting resin composition peeled off from the glass substrate was measured. The adhesive strength was calculated by dividing the stress by the width of the dot drawn with the thermosetting resin composition. The obtained adhesive strength was evaluated according to the following criteria: ◯ Adhesive strength of 1.0 N / mm or more △ Adhesive strength of 0.5 N / mm or more but less than 1.0 N / mm × Adhesive strength of less than 0.5 N / mm

[0114] (Moisture Resistance) A release film was placed on a glass plate, and the four sides of the glass plate were surrounded by 100 μm PET film pieces, and then the prepared thermosetting resin composition was applied. Then, a release film and a glass plate were further placed on the applied thermosetting resin composition, and the four sides of the glass plate were fixed with clips. The glass piece on which the coating film of the thermosetting resin composition was formed was kept in a hot air drying oven at 80 ° C. for 60 minutes, then removed and cooled. Then, the glass piece was disassembled, and the coating film was peeled off from the release paper to obtain a film with a thickness of 100 μm.

[0115] Using the obtained 100 μm film, an aluminum cup was prepared according to a method conforming to JIS Z0208:1976, and left in a high-temperature, high-humidity chamber at 60°C and 90% RH for 17 hours. The weight of the film after leaving it was measured. After that, the film was left again for 24 hours, and the weight of the film was measured, and the moisture permeability was calculated using the following formula. Moisture permeability (g / m ２ ・100 μm ・24 h) = [weight of aluminum cup after leaving for 24 hours (g) - weight of aluminum cup before leaving for 24 hours (g)] / film area (m ２ )

[0116] Based on the calculated moisture permeability, the moisture resistance was evaluated according to the following criteria: ○ Moisture permeability of 50 g / m ２ Less than △ Moisture permeability 50g / m ２ 80g / m or more ２ Less than 80g / m ２ End

[0117] The evaluation results are shown in Tables 1 and 2. The numerical values ​​of the compositions in Tables 1 and 2 represent parts by mass.

[0118]

[0119]

[0120] As shown in Table 1 above, the thermosetting resin compositions of Examples 1 to 7, which contained a compound (A) having a glycidyl group and a structure represented by formula (1) and a polyamine-based latent thermosetting agent (B), all exhibited excellent adhesive strength when stress was applied, and the sealant (thermosetting resin composition) was less likely to peel from the substrate. This is thought to be because the compound (A) having the structure represented by formula (1) was able to relieve stress. Furthermore, it was found that Examples 1 to 7 were able to improve moisture resistance.

[0121] In contrast, the thermosetting resin compositions of Comparative Examples 1 to 4, which did not contain the compound (A), exhibited low adhesive strength when stress was applied.

[0122] This application claims priority based on Japanese Patent Application No. 2022-049974, filed March 25, 2022. The contents of the specification and drawings of that application are incorporated herein by reference in their entirety.

[0123] According to the present invention, a thermosetting resin composition can be obtained that can suppress peeling from a substrate when stress is applied to a display device. The present invention is very useful for application to various display devices.

[0124] REFERENCE SIGNS LIST 100 Display device 110 Substrate 120 Cured sealant 130 Display element

Claims

1. The composition includes a compound (A) having a total of two or more functional groups selected from at least one of a glycidyl group and an oxetanyl group and having a structure represented by general formula (1), and a heat curing agent (B), The viscosity measured with an E-type viscometer at 25°C and 2.5 rpm is 20.0 Pa s or less. Thermosetting resin composition. 【Chemistry 1】 (In general formula (1), a represents an integer of 0 or more and 8 or less, b represents an integer of 0 or more and 3 or less, c represents an integer of 0 or more and 8 or less, d represents an integer of 0 or more and 8 or less, at least one of a, b and c is 1 or more, n is an integer of 1 or more, and * represents a bonding position. When compound (A) has a plurality of structures represented by general formula (1), the numbers of a, b, c, d and n in each structure may be the same or different.)

2. The thermosetting resin composition according to claim 1 , wherein the compound (A) further has a structure represented by general formula (2): 【Chemistry 2】 (In the general formula (2), R1 is any one of an alkylene group having 1 to 4 carbon atoms, an alkylidene group having 2 to 4 carbon atoms, an oxygen atom, and a sulfur atom, and * indicates a bonding position. When the compound (A) has a plurality of structures represented by the general formula (2), R1 in each structure may be the same or different.)

3. 2. The thermosetting resin composition according to claim 1, wherein the compound (A) is a bifunctional epoxy compound represented by the general formula (1), where a=3, b=0, c=0, d=0, a=1, b=1, c=0, d=0, or a=0, b=1, c=0, d=1.

4. The compound (A) is an epoxy compound having an epoxy equivalent of 300 g / eq or more; a cured product obtained by mixing 100 parts by mass of the compound (A), methylhexahydrophthalic anhydride in a chemical equivalent amount relative to 100 parts by mass of the compound (A), and 1 part by mass of dimethylbenzylamine and heating the mixture at 110° C. for 3 hours and then at 165° C. for 2 hours has a glass transition temperature of 100° C. or lower; The thermosetting resin composition according to claim 1 .

5. The heat curing agent (B) is at least one curing agent selected from the group consisting of dihydrazide-based heat curing agents, amine adduct-based heat curing agents, and polyamine-based heat curing agents. The thermosetting resin composition according to claim 1 .

6. The thermosetting resin composition according to claim 1, wherein the heat curing agent (B) is a polyamine-based latent heat curing agent having a melting point of 60°C or more and 110°C or less.

7. The compound (a) further includes a compound having at least one functional group selected from a glycidyl group and an oxetanyl group and a biphenyl structure. The thermosetting resin composition according to claim 1 .

8. The thermosetting resin composition according to claim 1 , further comprising an inorganic filler (C).

9. A sealant for a display device, comprising the thermosetting resin composition according to any one of claims 1 to 8.

10. A display device having a pair of substrates and a display element disposed between the pair of substrates, wherein the cured product of the sealant for a display device is used to seal the display element. The sealant for a display device according to claim 9 .

11. The sealant for a display device according to claim 9 , wherein the display device is an electrophoretic type or an electrochromic type display device.

12. A pair of substrates; A cured product of the sealant for a display device according to claim 9 , which is disposed between the pair of substrates; a display element disposed in a space surrounded by the cured product of the sealant for a display device between the pair of substrates; A display device having the above configuration.

Images