Sealant for display element, method for producing same, and display device

Abstract

The present invention addresses the problem of providing a sealant for a display element, which is capable of forming a uniform sealing layer even in the form of a thin film. A sealant for a display element that solves the problem contains: an epoxy compound (A) which has two or more epoxy groups in each molecule; an oxetane compound (B) which has one or more oxetanyl groups in each molecule; a cationic polymerization initiator (C); and a leveling agent (D). The viscosity measured by an E-type viscometer at 25°C and a number of revolutions of 20 rpm is 5 mPa∙s to 30 mPa∙s inclusive, and the number of particles having a particle diameter of 0.1 μm or more is 10,000 or less per 1 mL. The leveling agent (D) is composed of at least one substance that is selected from the group consisting of an ester-based leveling agent, a polyether-based leveling agent, and a (meth)acrylic polymer.

Description

Sealant for display element, method for producing same, and display device

[0001] The present invention relates to a sealant for a display element, a method for producing the same, and a display device.

[0002] In recent years, thin display devices have become widespread. Such thin display devices generally include a display element, such as an organic electroluminescence (hereinafter also referred to as "organic EL") element, and a sealing layer for protecting the element. In particular, the light-emitting layer and electrodes of the organic EL element are susceptible to deterioration due to moisture, oxygen, etc. Therefore, a method for protecting the organic EL element has been proposed, in which an inorganic barrier layer containing an inorganic material and a sealing layer containing an organic resin are stacked, or these layers are stacked alternately (e.g., Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2000-223264

[0004] The sealing layer containing the resin described above is generally formed by applying a sealant containing a curable resin by an inkjet method or the like and curing the applied sealant. Here, research is being conducted on micro organic EL display devices using semiconductor processes to further improve the resolution and contrast of display devices for mirrorless single-lens reflex cameras and AR (Augmented Reality) and VR (Virtual Reality) applications. In order to achieve even higher resolution in such display devices, research is being conducted on reducing the thickness of the sealing layer to, for example, 1 / 10 or less of the conventional thickness. However, with known sealants, it is difficult to form a sealing layer with such a very thin film thickness, and there are problems such as unevenness in film thickness and defects in the resulting sealing layer.

[0005] An object of the present invention is to provide a sealant for display elements that can form a uniform sealing layer even in a thin film, and a method for producing the same. Another object of the present invention is to provide a display device using the sealant for display elements.

[0006] The present invention provides the following sealant for display elements: [1] The sealant for display elements comprises an epoxy compound (A) having two or more epoxy groups per molecule, an oxetane compound (B) having one or more oxetanyl groups per molecule, a cationic polymerization initiator (C), and a leveling agent (D), wherein the sealant has a viscosity of 5 mPa·s to 30 mPa·s as measured at 25°C and 20 rpm using an E-type viscometer, and contains 10,000 or fewer particles having a particle size of 0.1 μm or larger per mL, and the leveling agent (D) is at least one selected from the group consisting of an ester-based leveling agent, a polyether-based leveling agent, and a (meth)acrylic polymer. [2] The sealant for display elements according to [1], which is an inkjet ink.

[0007] The present invention provides the following display device: [3] A display device comprising a display element, a first inorganic barrier layer containing an inorganic material, a sealing layer, and a second inorganic barrier layer containing an inorganic material, formed in this order, the sealing layer comprising a cured product of an epoxy compound (A) having two or more epoxy groups in one molecule and an oxetane compound (B) having one or more oxetanyl groups in one molecule, and a leveling agent (D), the leveling agent (D) being at least one selected from the group consisting of an ester-based leveling agent, a polyether-based leveling agent, and a (meth)acrylic polymer. [4] The display device according to [3], wherein the sealing layer has an average film thickness of 3 μm or less.

[0008] The present invention provides the following method for producing a sealant for display elements: [5] A method for producing a sealant for display elements, comprising the steps of: preparing a composition containing an epoxy compound (A) having two or more epoxy groups in one molecule, an oxetane compound (B) having one or more oxetanyl groups in one molecule, a cationic polymerization initiator (C), and a leveling agent (D), and filtering the composition through a filter having a pore size of 0.1 μm or less, wherein the leveling agent (D) is at least one selected from the group consisting of an ester-based leveling agent, a polyether-based leveling agent, and a (meth)acrylic polymer.

[0009] According to the sealant for a display element of the present invention, it is possible to form a thin sealing layer and to make the thickness of the layer uniform.

[0010] 1. Sealant for Display Elements The sealant for display elements of the present invention (hereinafter also simply referred to as "sealant") is a composition for forming a sealing layer for sealing various display elements. The sealant of the present invention is particularly suitable as a material for forming a layer (sealing layer) for sealing organic EL elements. Hereinafter, an example will be described in which the sealant is applied by an inkjet method to form a sealing layer, i.e., the sealant is an inkjet ink, but the method for applying the sealant is not limited to the inkjet method.

[0011] As described above, it has been difficult to form a thin sealing layer using known sealants. The reasons for this include the following: The formation of a sealing layer is often performed by an inkjet method. Furthermore, to reduce the thickness of the sealing layer, it is necessary to reduce the diameter of the inkjet nozzle and the amount of sealant dispensed. However, after extensive research, the inventors of the present invention found that when known sealants are ejected from a nozzle with a small diameter, the nozzle is easily clogged by coarse particles in the sealant. Even if the sealant can be ejected from the nozzle, unevenness in the film thickness occurs, making it impossible to form a uniform sealing layer, leading to a decrease in yield. On the other hand, it has also been found that removing coarse particles from the sealant by filtration easily removes the leveling agent along with the coarse particles. If the leveling agent is removed from the sealant in this way, the sealant is less likely to wet and spread sufficiently after being ejected from the nozzle, and the resulting sealing layer is also likely to be non-uniform in this case.

[0012] In contrast, the sealant of the present invention contains an epoxy compound (A), an oxetane compound (B), a cationic polymerization initiator (C), and a specific leveling agent (D). The sealant has a viscosity of 5 mPa·s or more and 30 mPa·s or less, as measured at 25°C and 20 rpm using an E-type viscometer. Furthermore, the number of particles having a particle size of 0.1 μm or more per mL of the sealant is 10,000 or less. Therefore, the sealant can be ejected from a small-diameter inkjet nozzle. The sealant of the present invention not only contains a small number of coarse particles, but also contains a leveling agent (D) selected from the group consisting of an ester-based leveling agent, a polyether-based leveling agent, and a (meth)acrylic polymer. These leveling agents (D) are difficult to remove by filtration. Therefore, when a desired amount of the leveling agent (D) is contained in the sealant and a sealing layer is formed, the sealant easily wets and spreads, and a uniform sealing layer can be formed even with a thin film thickness. Furthermore, since the sealant has a viscosity within the above range, it can be easily discharged by an inkjet method, and the discharged droplets easily wet and spread. Therefore, the sealant of the present invention can form a very thin sealing layer for a thin display device. The components contained in the sealant and the physical properties of the sealant will be described in detail below.

[0013] Epoxy Compound (A) In this specification, the epoxy compound (A) refers to a compound having two or more epoxy groups in one molecule. The epoxy compound is not particularly limited as long as it is a compound that can be photocured with a cationic polymerization curing agent described below. The sealing agent may contain only one type of epoxy compound (A), or may contain two or more types.

[0014] The epoxy compound (A) may be a solid compound or a liquid compound at 25° C., but a liquid compound is preferred from the viewpoint that the viscosity can be easily adjusted to the desired range. When the epoxy compound (A) is a liquid compound at 25° C., the viscosity of the epoxy compound (A) measured with an E-type viscometer under conditions of 25° C. and 20 rpm is preferably 1 mPa·s or more and 500 mPa·s or less, and more preferably 5 mPa·s or more and 100 mPa·s or less. When the viscosity of the epoxy compound (A) is within this range, the viscosity of the sealant can easily be adjusted to the desired range.

[0015] The epoxy compound (A) may be an alicyclic epoxy compound, an aliphatic epoxy compound, or an aromatic compound, but is particularly preferably an alicyclic epoxy compound. The number of epoxy groups contained in the epoxy compound (A) is preferably 2 or more and 4 or less, more preferably 2 or 3.

[0016] Examples of alicyclic epoxy compounds that can be the epoxy compound (A) include compounds having a cycloalkene oxide structure represented by the following general formula: The cycloalkene oxide structure is a structure obtained by epoxidizing a cycloalkene with an oxidizing agent such as a peroxide, and has an aliphatic ring and an epoxy group composed of two carbon atoms and an oxygen atom that constitute the aliphatic ring. In the above general formula, M represents an alicyclic structure, and the number of carbon atoms therein is preferably 4 or more and 8 or less, more preferably 5 or 6. When the number of carbon atoms in the alicyclic structure of the cycloalkene oxide structure is within this range, the viscosity of the sealant tends to fall within the desired range.

[0017] Specific examples of the cycloalkene oxide structure include cyclohexene oxide and cyclopentene oxide, with cyclohexene oxide being preferred.

[0018] The number of cycloalkene oxide structures contained in one molecule of the alicyclic epoxy compound may be one (monofunctional) or two or more (polyfunctional). In particular, the number of cycloalkene oxide structures contained in one molecule of the alicyclic epoxy compound is preferably two or more (polyfunctional) from the viewpoint of excellent heat resistance, etc.

[0019] Examples of the alicyclic epoxy compound having a cycloalkene oxide structure include compounds represented by the following general formulas (A-1) to (A-3).

[0020]

[0021] M in the above general formula (A-1) １ and M ２ represents an alicyclic structure, and as described above, the number of carbon atoms therein is preferably 4 or more and 8 or less, more preferably 5 or 6. １ is a single bond or a linking group. Examples of the linking group include a divalent hydrocarbon group, a carbonyl group, an ether group (ether bond), a thioether group (thioether bond), an ester group (ester bond), a carbonate group (carbonate bond), an amide group (amide bond), or a group in which a plurality of these groups are linked together.

[0022] Examples of divalent hydrocarbon groups include alkylene groups having 1 to 18 carbon atoms and divalent alicyclic hydrocarbon groups. Examples of alkylene groups having 1 to 18 carbon atoms include methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene. Examples of divalent alicyclic hydrocarbon groups include divalent cycloalkylene groups (including cycloalkylidene groups) such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene.

[0023] Among them, X １is preferably a single bond or a linking group having an oxygen atom. The linking group having an oxygen atom is more preferably —CO— (carbonyl group), —O—CO—O— (carbonate group), —COO— (ester group), —O— (ether group), —CONH— (amide group), a group in which a plurality of these groups are linked together, or a group in which one or more of these groups are linked to one or more divalent hydrocarbon groups.

[0024] Specific examples of the alicyclic epoxy compound represented by general formula (A-1) include the following compounds. In the following formula, l is an integer of 1 to 10, and m is an integer of 1 to 30. R is an alkylene group having 1 to 8 carbon atoms (preferably an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, a propylene group, or an isopropylene group). n1 and n2 are each an integer of 1 to 30.

[0025]

[0026] Examples of commercially available alicyclic epoxy compounds represented by the general formula (A-1) include Celloxide 2021P, Celloxide 2081, Celloxide 8000, and Celloxide 8010 (all manufactured by Daicel Corporation).

[0027] On the other hand, the alicyclic epoxy compound having a cycloalkene oxide structure may be a compound having a structure represented by the following general formula (A-2) or (A-3).

[0028] M in the above general formulae (A-2) and (A-3) ３ , M ４ , and M ５ represents an alicyclic structure, the number of carbon atoms of which is preferably 4 or more and 8 or less, more preferably 5 or 6. ２ is a single bond or a linking group. The linking group is the same as the linking group in the general formula (A-1) described above. In the compounds represented by the general formulas (A-2) and (A-3), an alkyl group or the like may be bonded to a carbon atom constituting the alicyclic structure or the epoxy group.

[0029] Examples of the alicyclic epoxy compounds represented by the general formula (A-2) or (A-3) include 3,4:7,8-diepoxybicyclo[4.3.0]nonane, limonene dioxide, etc. Examples of commercially available products of these compounds include THI-DE (manufactured by JX-TG Corporation) and LDO (manufactured by Nagase Chemtec Corporation).

[0030] On the other hand, examples of aliphatic epoxy compounds that can be the epoxy compound (A) include polyglycidyl ethers containing a structure derived from an aliphatic polyhydric alcohol or its alkylene oxide adduct. The aliphatic polyhydric alcohol may be linear or may have a partial cyclic structure (excluding the above-mentioned alicyclic epoxy compounds). From the viewpoint that the viscosity of the sealant is likely to fall within the desired range, the aliphatic polyhydric alcohol is preferably linear. Therefore, the aliphatic epoxy compound is particularly preferably a diglycidyl ether of an alkanediol or its alkylene oxide adduct.

[0031] Examples of the aliphatic epoxy compound include diglycidyl ethers of alkanediols having 4 to 6 carbon atoms, such as 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether; triglycidyl ethers of glycerin, trimethylolpropane, and the like; tetraglycidyl ether of sorbitol; hexaglycidyl ether of dipentaerythritol; diglycidyl ethers of polyethylene glycol, polypropylene glycol, and the like; and polyglycidyl ethers of alkylene oxide adducts (polyether polyols), such as propylene glycol and trimethylolpropane.

[0032] Examples of commercially available aliphatic epoxy compounds include SR-PG, SR-2EGS, SR-8EGS, SR-14BJ, and SY-25L (manufactured by Sakamoto Pharmaceutical Co., Ltd.), Epogosey 2EH, Epogosey HD(D), Epogosey NPG(D), and Epogosey BD(D) (manufactured by Yokkaichi Synthetic Co., Ltd.), and Denacol EX-121, Denacol EX-212L, and Denacol EX-214L (manufactured by Nagase ChemteX Corporation).

[0033] Examples of aromatic epoxy compounds include glycidyl ethers of polyhydric alcohols containing an aromatic ring, bisphenol A type epoxy resins, bisphenol E type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol O type epoxy resins, 2,2'-diallyl bisphenol A type epoxy resins, propylene oxide-added bisphenol A type epoxy resins, resorcinol type epoxy resins, biphenyl type epoxy resins, sulfide type epoxy resins, diphenyl ether type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins, ortho-cresol novolac type epoxy resins, biphenyl novolac type epoxy resins, and naphthalene phenol novolac type epoxy resins.

[0034] Regardless of the structure of the epoxy compound (A), its molecular weight is preferably 180 or more, more preferably 190 or more, and even more preferably 200 or more. The upper limit of the molecular weight is sufficient as long as the viscosity of the sealant falls within the desired range, and is usually preferably 400 or less. When the molecular weight of the epoxy compound (A) is 180 or more, volatilization of the epoxy compound (A) from the sealant can be suppressed. As a result, when the sealant is applied by an inkjet method, the composition is less likely to change, and further, the working environment is less likely to deteriorate. The molecular weight of the epoxy compound (A) may be determined from its structure. Alternatively, the weight average molecular weight may be measured in terms of polystyrene by gel permeation chromatography (GPC).

[0035] Furthermore, the surface tension of the epoxy compound (A) at 25°C (when multiple epoxy compounds (A) are contained, the surface tension of each epoxy compound (A)) is preferably 15 N / mm or more and 50 N / mm or less, and more preferably 20 N / mm or more and 40 N / mm or less. When the surface tension of the epoxy compound (A) is within this range, the surface tension of the sealant tends to fall within the desired range. The above surface tension is a value measured by the Wilhelmy method using a surface tensiometer.

[0036] The content of the epoxy compound (A) (when a plurality of epoxy compounds (A) are contained, the total amount thereof) is preferably 10% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less, based on the total amount of the sealant. When the amount of the epoxy compound (A) is within this range, a uniform sealing layer can be easily formed, and further, the resulting sealing layer can easily protect various elements.

[0037] Oxetane Compound (B) The oxetane compound may be any compound having one or more oxetanyl groups per molecule, and may be either a solid compound or a liquid compound at 25°C. However, a liquid compound is preferred from the viewpoint that the viscosity of the sealant is more likely to fall within the desired range. When the oxetane compound (B) is liquid at 25°C, the viscosity of the oxetane compound (B) measured with an E-type viscometer at 25°C and 20 rpm is preferably 1 to 500 mPa·s, more preferably 1 to 300 mPa·s. When the viscosity of the oxetane compound (B) is within this range, the viscosity of the sealant is more likely to fall within the desired range.

[0038] The oxetane compound (B) is preferably a compound represented by the following general formula (B-1) or (B-2): The sealing agent may contain only one type of oxetane compound (B), or may contain two or more types.

[0039]

[0040] In the general formulas (B-1) and (B-2), Y represents an oxygen atom, a sulfur atom, or a single bond. Of these, an oxygen atom is preferred.

[0041] Also, R １ａ and R １ｂ each represents a fluorine atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group having 6 to 18 carbon atoms, a furyl group, or an ethynyl group. m and n each represent an integer of 1 to 5. R １ａ Or R １ｂ When a plurality of R are contained in one molecule, they may be the same or different. １ａR between or adjacent １ｂ They may form a ring structure.

[0042] In addition, R in general formula (B-1) ２ａ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, an N-alkylcarbamoyl group having 2 to 6 carbon atoms, or a (meth)acryloyl group. In this specification, (meth)acryloyl represents methacryl, acryloyl, or both. The same applies to (meth)allyl, (meth)acrylic, etc.

[0043] On the other hand, R in general formula (B-2) ２ｂ represents a p-valent linking group, where p is 2, 3, or 4. ２ｂ represents, for example, a linear or branched alkylene group having 1 to 12 carbon atoms, a linear or branched poly(alkyleneoxy) group, an arylene group, a siloxane bond, or a combination thereof.

[0044] In particular, from the viewpoint of making it easier for the viscosity of the sealant to fall within the desired range, the oxetane compound is preferably a compound represented by the following general formula (B-3) or (B-4).

[0045]

[0046] In the above general formulas (B-3) and (B-4), Y is an oxygen atom or a sulfur atom. １ｃ , R １ｄ , or R ２ｄ represents a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, a furyl group, or a thienyl group. Among these, an alkyl group having 1 to 6 carbon atoms is preferred from the viewpoint that the viscosity of the sealant is more likely to fall within the desired range.

[0047] R ２ｃis a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, an N-alkylcarbamoyl group having 2 to 6 carbon atoms, or a (meth)acryloyl group. Of these, an alkyl group having 1 to 10 carbon atoms is more preferred from the viewpoint of reducing the viscosity of the composition.

[0048] Examples of the compound represented by general formula (B-3) include 3-ethyl-3-hydroxymethyloxetane, 3-(meth)allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy)methylbenzene, 4-fluoro-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 4-methoxy-[1-(3-ethyl-3-oxetanylmethoxy)methyl]benzene, [1-(3-ethyl-3-oxetanylmethoxy)ethyl]phenyl ether, isobutoxymethyl(3-ethyl-3-oxetanylmethyl)ether, isobornyloxyethyl ( Examples of the compound represented by general formula (B-4) include 3,3'-(oxybismethylene)bis(3-ethyloxetane), isobornyl(3-ethyl-3-oxetanylmethyl)ether, 2-ethylhexyl(3-ethyl-3-oxetanylmethyl)ether, ethyldiethyleneglycol(3-ethyl-3-oxetanylmethyl)ether, dicyclopentadiene(3-ethyl-3-oxetanylmethyl)ether, 3-methacryloxymethyl-3-ethyloxetane, and 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, with 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane being particularly preferred. Examples of the compound represented by general formula (B-4) include 3,3'-(oxybismethylene)bis(3-ethyloxetane).

[0049] Examples of commercially available oxetane compounds include OXT-221, OXT-121, and OXT-212 (all manufactured by Toagosei Co., Ltd.), OXBP, and HBOX (all manufactured by Ube Industries, Ltd.).

[0050] The molecular weight of the oxetane compound (B) is preferably 180 or more. When the molecular weight of the oxetane compound (B) is 180 or more, the oxetane compound (B) is less likely to volatilize in an inkjet device, and the composition of the sealant is less likely to change. From the viewpoint of suppressing volatilization of the oxetane compound, the molecular weight of the oxetane compound (B) is preferably 190 or more, more preferably 200 or more. The upper limit of the molecular weight may be any value as long as the viscosity of the sealant falls within the desired range, but is usually preferably 400 or less. The molecular weight may be determined from the structure, or the weight average molecular weight may be determined in the same manner as for the epoxy compound (A).

[0051] Furthermore, the surface tension of the oxetane compound (B) at 25°C (when multiple oxetane compounds (B) are contained, the surface tension of each individual oxetane compound) is preferably 15 N / mm or more and 50 N / mm or less, and more preferably 20 N / mm or more and 45 N / mm or less. When the surface tension of the oxetane compound (B) is within this range, the surface tension of the sealant tends to fall within the desired range. The above surface tension is a value measured by the Wilhelmy method using a surface tensiometer.

[0052] The content of the oxetane compound (B) (when a plurality of oxetane compounds (B) are contained, the total amount thereof) is preferably 20% by mass or more and 80% by mass or less, and more preferably 30% by mass or more and 75% by mass or less, relative to the total amount of the sealant. When the amount of the oxetane compound (B) is within this range, a uniform sealing layer can be easily formed, and further, the resulting sealing layer can easily protect various elements.

[0053] Cationic Polymerization Initiator (C) The cationic polymerization initiator (C) is preferably a compound that generates an active species capable of initiating cationic polymerization upon irradiation with actinic rays such as ultraviolet rays (e.g., ultraviolet light). The sealing agent may contain only one type of cationic polymerization initiator (C), or may contain two or more types.

[0054] Examples of the cationic polymerization initiator (C) include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, etc. The anion moiety of these is BF ４ － , P.X. ６ －(X is fluorine or a fluoroalkyl group), SbF ６ － or BX ４ － (X is preferably a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups).

[0055] Examples of the aromatic sulfonium salt include bis[4-(diphenylsulfonio)phenyl]sulfide bishexafluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide bishexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide bistetrafluoroborate, bis[4-(diphenylsulfonio)phenyl]sulfide tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, and the like.

[0056] Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, and the like.

[0057] Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, phenyldiazonium tetrakis(pentafluorophenyl)borate, and the like.

[0058] Examples of the aromatic ammonium salts include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, and the like.

[0059] Examples of commercially available cationic polymerization initiators (C) include Irgacure 250, Irgacure 270, and Irgacure 290 (manufactured by BASF), CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-210K, CPI-310B, CPI-310FG, and CPI-400PG (manufactured by San-Apro Co., Ltd.), and SP-150, SP-170, SP-171, SP-056, SP-066, SP-130, SP-140, SP-601, SP-606, and SP-701 (manufactured by ADEKA Corporation). Of these, sulfonium salts such as Irgacure 270, Irgacure 290, CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-210K, CPI-310B, CPI-310FG, CPI-400PG, SP-150, SP-170, SP-171, SP-056, SP-066, SP-601, SP-606, and SP-701 are preferred.

[0060] The content of the cationic polymerization initiator (C) (when a plurality of cationic polymerization initiators (C) are contained, the total amount thereof) is preferably 0.5% by mass or more and 2.5% by mass or less, and more preferably 0.8% by mass or more and 1.3% by mass or less, relative to the total amount of the sealant. When the amount of the cationic polymerization initiator (C) is within this range, the photocurability of the sealant tends to be good.

[0061] Leveling Agent (D) The leveling agent is a compound that adjusts the surface tension of the sealant coating film to improve the wettability of the sealant to the substrate, and further increases the fluidity and defoaming properties of the coating film, thereby improving the flatness of the sealing layer. The leveling agent (D) is at least one selected from the group consisting of ester-based leveling agents, polyether-based leveling agents, and (meth)acrylic polymers. The sealant may contain only one type of leveling agent (D), or may contain two or more types.

[0062] As described above, the sealant of the present invention has a particle size of 0.1 μm or more per mL of 10,000 or less. Filtration is performed during the production of such a sealant. Here, when removing coarse particles of the sealant or its raw materials by filtration, a PTFE filter is generally used. In contrast, ester-based leveling agents, ether-based leveling agents, and (meth)acrylic polymers are difficult to filter through such filters.

[0063] Examples of ester-based leveling agents include polyester-modified acrylic group-containing polydimethylsiloxane, polyester-modified polydimethylsiloxane, polyester polyol, etc. Among these, polyester-modified polydimethylsiloxane is preferred. The polyester-modified polydimethylsiloxane may be a compound having a polydimethylsiloxane skeleton and a polyester chain bonded to the polydimethylsiloxane skeleton. The polyester-modified polydimethylsiloxane may be a commercially available product, examples of which include BYK-310 and BYK-370 (both manufactured by BYK Japan).

[0064] Examples of polyether-based leveling agents include cellulose ether; pullulan; polyethylene glycol; silicone-modified polyethers such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyetherester-modified hydroxyl group-containing polydimethylsiloxane, and polyether-modified acrylic group-containing polydimethylsiloxane; polyglycerin; polyether polyol, polyoxyethylene-polyoxypropylene condensate, polyoxyethylene alkylphenyl ether, alkyl ether derivatives such as lauryl alcohol alkoxylate, and alkyl ether sulfates. Among these, polyether-modified polydimethylsiloxane is preferred. The polyether-modified polydimethylsiloxane may be a compound having a polydimethylsiloxane skeleton and a polyether chain bonded to the polydimethylsiloxane skeleton. The polyether-modified polydimethylsiloxane may be a commercially available product, and examples thereof include BYK-333, BYK-330, BYK-302, and BYK-UV3500 (all manufactured by BYK Japan).

[0065] The (meth)acrylic polymer is, for example, a polymer (also referred to as "polyacrylate" in this specification) obtained by homopolymerizing or copolymerizing a monomer having a (meth)acryloyl group. Examples of the monomer having a (meth)acryloyl group include (meth)acrylates having a hydroxyl group and (meth)acrylates having an alkylene oxide such as ethylene oxide. The (meth)acrylic polymer preferably contains a structure derived from such a monomer having a hydrophilic group.

[0066] The (meth)acrylic polymer may be a commercially available product, examples of which include BYK-350, BYK-352, BYK-353, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-361N, BYK-380, BYK-381, BYK-392, BYK-394, and BYK-3441 (all manufactured by BYK Japan).

[0067] The content of the leveling agent (D) (when a plurality of leveling agents (D) are contained, the total amount thereof) is preferably 0.01 mass % or more and 1 mass % or less, and more preferably 0.1 mass % or more and 0.5 mass % or less, relative to the total amount of the sealant. When the amount of the leveling agent (D) is within this range, the coating film tends to be smooth when the sealant is applied, and a uniform sealing layer tends to be obtained.

[0068] Other Components The sealant may further contain components other than those described above, provided that the purpose and effects of the present invention are not impaired. Examples of such other components include a sensitizer and an ultraviolet absorber.

[0069] The sensitizer is a compound that has the function of improving the efficiency of active species generation by the cationic polymerization initiator (C) and accelerating the curing reaction of the sealing agent. Examples of the sensitizer include thioxanthone compounds such as 2,4-diethylthioxanthone, benzophenone compounds such as 2,2-dimethoxy-1,2-diphenylethan-1-one, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide, and anthracene compounds such as 9,10-diethoxyanthracene, 9,10-dibutoxyanthracene, and 9,10-bis(octanoyloxy)anthracene.

[0070] The content of the sensitizer (when multiple sensitizers are used, the total amount of these sensitizers) is preferably 0.1% by mass or more and 2.5% by mass or less, and more preferably 0.5% by mass or more and 2% by mass or less, relative to the total amount of the sealant. When the amount of the sensitizer is within this range, the sealant has good curability.

[0071] Examples of ultraviolet absorbers include benzotriazole compounds, benzophenone compounds, triazine compounds, and cyanoacrylate compounds.

[0072] Examples of the benzotriazole compound include 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2,2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl, 2-(2'-hydroxy-5'-methyl-phenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butyl-phenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methyl-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-butyl-phenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)-phenol, 2-(2-hydroxy-5-methylphenyl)benzotriazole, and 2-(2'-hydroxy-4'-n-octoxy-phenyl)benzotriazole. Preferred are 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)-phenol, 2-(2-hydroxy-5-methylphenyl)benzotriazole, and 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole. More preferred are 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)-phenol and 2-(2-hydroxy-5-methylphenyl)benzotriazole, and even more preferred are 2-(2-hydroxy-5-methylphenyl)benzotriazole.

[0073] As the benzotriazole compound, commercially available products can also be used. Examples of commercially available benzotriazole compounds include Tinuvin 234 (2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)-phenol, manufactured by BASF Japan Ltd.), KEMISORB71 (2-(2-hydroxy-5-methylphenyl)benzotriazole, manufactured by Chemipro Chemical Co., Ltd.), and RUVA-93 (2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, manufactured by Otsuka Chemical Co., Ltd.).

[0074] Examples of the benzophenone compound include [2-hydroxy-4-(octyloxy)phenyl](phenyl)methanone, 2-hydroxy-4-n-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2 2-hydroxy-4-methoxy-2'-carboxy benzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2-hydroxy-4-n-dodecyloxy benzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2,2',4,4'-tetrahydroxy benzophenone, 2-hydroxy-4-dodecyloxy-benzophenone, and 2-hydroxy-4-(2-hydroxy-3-methacryloxy)propoxybenzophenone. Preferred are [2-hydroxy-4-(octyloxy)phenyl](phenyl)methanone and 2-hydroxy-4-n-octyloxybenzophenone. More preferred is 2-hydroxy-4-n-octyloxybenzophenone.

[0075] As the benzophenone compound, commercially available products can also be used, such as KEMISORB12 (2-hydroxy-4-n-octyloxybenzophenone, manufactured by Chemipro Chemicals Co., Ltd.) and Adekastab 1413 ([2-hydroxy-4-(octyloxy)phenyl](phenyl)methanone, manufactured by ADEKA Corporation).

[0076] Examples of the triazine compound include 2-[4,6-di(2,4-xylyl)-1,3,5-triazin-2-yl]-5-octyloxyphenol and 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, and preferably 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine.

[0077] Commercially available triazine compounds can also be used, such as KEMISORB102 (2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, manufactured by Chemipro Chemicals).

[0078] An example of the cyanoacrylate compound is ethyl-2-cyano-3-(3',4'-methylenedioxyphenyl)-acrylate.

[0079] Among the above, benzotriazole compounds, benzophenone compounds, and triazine compounds are preferred, benzotriazole compounds and benzophenone compounds are more preferred, and benzotriazole compounds or benzophenone compounds are even more preferred.

[0080] Furthermore, the sealant preferably contains a small amount of components that may affect the display element, and particularly a small amount of organic solvents. The amount of organic solvent is preferably less than 0.05% by mass, more preferably 0.01% by mass or less, and even more preferably substantially no organic solvent is contained, relative to the total amount of the sealant.

[0081] Physical Properties of the Sealant The sealant has a viscosity of 5 mPa·s or more and 30 mPa·s or less, measured at 25°C and 20 rpm using an E-type viscometer. As described above, when the sealant has a viscosity within this range, not only is the sealant easy to eject from an inkjet nozzle, but the droplets after application also easily wet and spread, making it easier to obtain a flat sealing layer. The viscosity is preferably 5 mPa·s or more and 50 mPa·s or less, and more preferably 8 mPa·s or more and 30 mPa·s or less.

[0082] Furthermore, in this sealant, the number of particles having a particle size of 0.1 μm or more present per mL is 10,000 or less. As described above, when the number of particles is 10,000 or less, the sealant can be ejected from inkjet nozzles with small diameters. Furthermore, when a thin sealing layer is formed, the sealing layer is likely to be flat. The number of particles is more preferably 8,000 or less, and even more preferably 6,000 or less. The number of particles having a particle size of 0.1 μm or more can be determined using a liquid-borne particle sensor KS-42A. Furthermore, in this specification, the particle size is a value determined using a semiconductor laser with a wavelength of 830 nm.

[0083] The surface tension of the sealant at 25°C is preferably 25 N / mm or more and 38 N / mm or less, more preferably 28 N / mm or more and 35 N / mm or less. When the surface tension of the sealant is within this range, the sealant easily spreads when applied. The surface tension of the sealant can be measured by the Wilhelmy method using a surface tensiometer.

[0084] Method for Producing the Sealant There are no particular limitations on the method for preparing the sealant, as long as the sealant can be prepared so that the number of particles having a particle size of 0.1 μm or more is 10,000 or less and the sealant contains the epoxy compound (A), the oxetane compound (B), the cationic polymerization initiator (C), and the leveling agent (D).

[0085] For example, the sealant can be prepared by the steps of preparing a composition containing the epoxy compound (A), the oxetane compound (B), the cationic polymerization initiator (C), and the leveling agent (D), and filtering the composition through a filter having a pore size of 0.1 μm or less. The leveling agent (D) is at least one selected from the group consisting of ester-based leveling agents, polyether-based leveling agents, and (meth)acrylic polymers. By using such a leveling agent (D), the leveling agent (D) is less likely to be removed by filtration, and a sufficient amount of the leveling agent (D) can be contained in the sealant after preparation.

[0086] The filtration is preferably carried out by pressure filtration in a glove box using a capsule-type cartridge filter having a pore size of 0.1 μm or less at a maximum operating pressure of 0.39 MPa (25° C.). The filtration may be carried out multiple times, and is usually preferably carried out one to five times.

[0087] The method for producing the sealant is not limited to the above method, and for example, each component may be filtered and then mixed. However, since impurities (coarse particles) may be mixed during mixing, it is more preferable to mix all the components and then filter them as described above.

[0088] 2. Display Device The present invention also provides a display device having a sealing layer formed using the above-described sealant. The configuration of the display device is not particularly limited, and may be, for example, a configuration in which a display element, a first inorganic barrier layer containing an inorganic material, a sealing layer, and a second inorganic barrier layer containing an inorganic material are formed in this order. However, the configuration of the display device is not limited to this configuration, and for example, the second inorganic barrier layer may not be formed. Furthermore, other components may be included as necessary.

[0089] The type of display element in the display device is not particularly limited, and may be any known display element that requires sealing. One example of the display element is an organic EL element.

[0090] Furthermore, the first inorganic barrier layer and the second inorganic barrier layer are preferably composed of a film (hereinafter also referred to as "inorganic film") made of an inorganic material having water vapor barrier properties and oxygen barrier properties. The first inorganic barrier layer and the second inorganic barrier layer may each be composed of a single inorganic film, or may be composed of two or more inorganic film layers. Examples of inorganic materials that may constitute the inorganic film include oxides such as aluminum oxide, magnesium oxide, and silicon oxide; fluorides such as aluminum fluoride and magnesium fluoride; and nitrides such as aluminum nitride and silicon nitride. Each inorganic film may be formed by resistance heating evaporation, electron beam evaporation, reactive evaporation, atomic layer deposition, ion plating, sputtering, or the like.

[0091] The average film thickness of each of the first inorganic barrier layer and the second inorganic barrier layer is preferably from 0.1 μm to 100 μm, more preferably from 0.1 μm to 100 μm.

[0092] On the other hand, the sealing layer can be a film formed using the above-mentioned sealant, i.e., a cured product of the above-mentioned sealant. The method for forming the sealing layer is not particularly limited, and it is preferably a film formed by coating using a known coating method and curing the coating.

[0093] The method for applying the sealant is appropriately selected depending on the desired film thickness, etc., but application by an inkjet method is preferred. As described above, the sealant of the present invention can be ejected from an inkjet nozzle with a small diameter. The inkjet method also has the advantage of being able to reduce the film thickness of the sealing layer. When applying the sealant by the inkjet method, the amount of liquid ejected from the nozzle is preferably about 0.5 pL μm or more and 10 pL or less, more preferably 2 pL or more and 5 pL or less.

[0094] Furthermore, the method for curing the coating film of the sealant is preferably photocuring. The light source used for photocuring is appropriately selected depending on the absorption wavelength of the cationic polymerization initiator. The wavelength of the irradiated light is preferably, for example, 350 to 450 nm, more preferably 395 to 405 nm. Examples of light sources include xenon lamps, carbon arc lamps, and LED lamps (e.g., UV-LEDs), with LEDs being more preferred. Furthermore, the cumulative light amount is, for example, 1,000 to 20,000 mJ / cm. ２ If necessary, heating may be carried out before, during, or after the light irradiation.

[0095] The average thickness of the sealing layer is preferably 0.1 μm to 5 μm, more preferably 0.1 μm to 3 μm, and more preferably 0.3 μm to 1 μm. When the average thickness of the sealing layer is 0.3 μm or more, the sealing layer tends to be uniform, further improving the sealing properties of the display element. On the other hand, when the average thickness of the sealing layer is 1 μm or less, the thickness of the entire display device can be reduced.

[0096] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0097] 1. Preparation of Sealant (1) Preparation of Materials The following materials were used in the Examples and Comparative Examples.

[0098] [Epoxy compound (A)] CEL2021P: a compound represented by the following formula (Celloxide 2021P, manufactured by Daicel Corporation, molecular weight 252, viscosity at 25°C: 280 mPa·s (E-type viscometer, 20 rpm), surface tension at 25°C: 47 N / mm) CEL8000: a compound represented by the following formula (Celloxide 8000, manufactured by Daicel Corporation, molecular weight 194, viscosity at 25°C: 60 mPa·s (E-type viscometer, 20 rpm), surface tension at 25°C: 45.5 N / mm) SR-PG: an aliphatic epoxy compound represented by the following formula (SR-PG, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., viscosity at 25°C: 15 mPa s (E-type viscometer, 20 rpm), surface tension at 25°C: 40 N / mm)

[0099] [Oxetane compound (B): OXT-221: 3,3'-(oxybismethylene)bis(3-ethyloxetane) (OXT-221, manufactured by Toagosei Co., Ltd., viscosity at 25°C: 12 mPa·s (E-type viscometer, 20 rpm), surface tension at 25°C: 34.5 N / mm]

[0100] [Cationic polymerization initiator (C)] CPI-210K (manufactured by San-Apro Co., Ltd.)

[0101] [Leveling Agent (D)] BYK310: Polyester-modified polydimethylsiloxane (BYK-310, manufactured by BYK-Chemie) BYK350: Polyacrylate (BYK-350, manufactured by BYK-Chemie) BYK322: Aralkyl-modified polymethylalkylsiloxane (BYK-322, manufactured by BYK-Chemie)

[0102] (2) Preparation of Sealant (Examples 1 to 4, and Comparative Examples 2 and 3) The epoxy compound (A), oxetane compound (B), cationic polymerization initiator (C), and leveling agent (D) were placed in a flask and mixed so as to obtain the composition (feed ratio) shown in Table 1. The resulting mixture was stirred until no powdery material was visible. Then, using a capsule-type cartridge filter with a pore size (opening) of 0.1 μm, pressure filtration was carried out 20 times in a glove box.

[0103] Comparative Example 1 The epoxy compound (A), oxetane compound (B), cationic polymerization initiator (C), and leveling agent (D) were placed in a flask and mixed to obtain the composition shown in Table 1. The resulting mixture was stirred until no powdery material was visible. Then, using a capsule-type cartridge filter with a pore size (opening) of 0.5 μm, pressure filtration was carried out 20 times in a glove box.

[0104] (3) Viscosity Measurement The viscosity of the sealants prepared in each of the Examples and Comparative Examples at 25°C was measured using an E-type viscometer (20 rpm). The measured viscosities were evaluated as follows. The results are shown in Table 1. ○: The viscosity is 5 mPa·s or more and 30 mPa·s or less ×: The viscosity is less than 5 mPa·s or more than 30 mPa·s

[0105] (4) Evaluation of the Number of Particles The number of particles with a particle size of 0.1 μm or more present per mL in the sealant prepared in each Example and Comparative Example was measured using a liquid-borne particle sensor KS-42A. The measured values ​​were evaluated as follows. The results are shown in Table 1. ○: The number of particles with a particle size of 0.1 μm or more was 10,000 particles / mL or less. ×: The number of particles with a particle size of 0.1 μm or more was more than 10,000 particles / mL.

[0106] 3. Evaluation Each sealant was evaluated for the change in surface tension before and after filtration during the preparation described above, the continuous coating property using an inkjet device, and the wetting and spreading property. The results are shown in Table 1.

[0107] (1) Change in surface tension before and after filtration In preparing the sealant, the surface tension before and after filtration was measured using a surface tensiometer by the Wilhelmy method. The obtained values ​​were evaluated according to the following criteria: ○: The change in surface tension before and after filtration was less than 0.5 N / mm ×: The change in surface tension before and after filtration was 0.5 N / mm or more

[0108] (2) Continuous Coating Ability The sealants of the above Examples and Comparative Examples were ejected using an inkjet device DMP-2831 (manufactured by Fujifilm Dimatix Corporation) and an inkjet head SAMBA G3L (liquid volume: 2.4 pL). More specifically, 1000 droplets were ejected at a 500 μm pitch onto a 50 mm × 50 mm alkali-free glass, and then the nozzle was left for 3 hours without ejection in an environment of 23°C. 1000 droplets were ejected again, and the nozzle was left for another 3 hours. This cycle was performed three times, and the number of droplets in the first cycle was compared with the number of droplets in the third cycle. Evaluation was then performed according to the following criteria. ○: The ratio of the number of droplets in the third cycle to the initial number of droplets is more than 90%. ×: The ratio of the number of droplets in the third cycle to the initial number of droplets is less than 90%.

[0109] (3) Wetting and Spreading Properties The sealants of the above Examples and Comparative Examples were ejected onto a silicon wafer using an inkjet device DMP-2831 (manufactured by Fujifilm Dimatix Corporation) and an inkjet head SAMBA G3L (liquid volume: 2.4 pL). The droplet diameters 30 seconds after ejection and 3 minutes after ejection were measured using a scanning white light interference microscope. The evaluation was performed according to the following criteria: ○: The droplet diameter 3 minutes after ejection is equal to or greater than the droplet diameter 30 seconds after ejection. ×: The droplet diameter 3 minutes after ejection is less than the droplet diameter 30 seconds after ejection.

[0110]

[0111] As shown in Table 1 above, when the sealant contained more than 10,000 particles with a particle size of 0.1 μm or more per mL, continuous application was poor, nozzle clogging occurred, and it was difficult to form a uniform sealing layer (Comparative Example 1). Furthermore, when the sealant had a viscosity outside the specified range, wetting and spreading properties were poor, and in this case too, it was difficult to form a uniform sealing layer (Comparative Example 2). Furthermore, in Comparative Example 3, a sealant was prepared using an aralkyl-modified polymethylalkylsiloxane. However, in this case, the change in surface tension due to filtration was large, and wetting and spreading properties were also poor. It is believed that the leveling agent (D) was removed by filtration.

[0112] In contrast, a sealant containing an epoxy compound (A), an oxetane compound (B), a cationic polymerization initiator (C), and a leveling agent (D) made of a polyester or (meth)acrylic polymer, satisfying a predetermined viscosity, and containing 10,000 or less particles having a particle size of 0.1 μm or more, exhibited good continuous coating properties and good wetting and spreading properties, and was able to form a uniform sealing layer (Examples 1 to 4).

[0113] This application claims priority from Japanese Patent Application No. 2024-047915, filed March 25, 2024, the entire contents of which are incorporated herein by reference.

[0114] The sealant of the present invention can be applied from a nozzle with a small opening diameter, making it possible to form a thin sealing layer. Furthermore, the resulting sealing layer is less likely to have unevenness. Therefore, the sealant is extremely useful in the field of manufacturing various display devices.

Claims

1. A sealant for display elements, comprising: an epoxy compound (A) having two or more epoxy groups in one molecule; an oxetane compound (B) having one or more oxetanyl groups in one molecule; a cationic polymerization initiator (C); and a leveling agent (D), wherein the sealant has a viscosity of 5 mPa·s or more and 30 mPa·s or less as measured at 25°C and 20 rpm using an E-type viscometer; the number of particles having a particle size of 0.1 μm or more present per mL is 10,000 or less; and the leveling agent (D) is at least one selected from the group consisting of ester-based leveling agents, polyether-based leveling agents, and (meth)acrylic polymers.

2. The sealant for display elements according to claim 1, which is an inkjet ink.

3. A display device comprising: a display element; a first inorganic barrier layer containing an inorganic material; a sealing layer; and a second inorganic barrier layer containing an inorganic material, which are formed in this order; the sealing layer containing a cured product of an epoxy compound (A) having two or more epoxy groups in the molecule and an oxetane compound (B) having one or more oxetanyl groups in one molecule, and a leveling agent (D), and the leveling agent (D) is at least one selected from the group consisting of an ester-based leveling agent, a polyether-based leveling agent, and a (meth)acrylic polymer.

4. The display device according to claim 3, wherein the sealing layer has an average thickness of 3 μm or less.

5. A method for producing an encapsulant for display elements, comprising: a step of preparing a composition containing an epoxy compound (A) having two or more epoxy groups in one molecule, an oxetane compound (B) having one or more oxetanyl groups in one molecule, a cationic polymerization initiator (C), and a leveling agent (D); and a step of filtering the composition through a filter having a pore size of 0.1 μm or less, wherein the leveling agent (D) is at least one selected from the group consisting of an ester-based leveling agent, a polyether-based leveling agent, and a (meth)acrylic polymer.

Images