Sealing agent for display element, method for manufacturing the same, and display device

Abstract

The present invention provides a display element sealant capable of forming a uniform seal layer even if it is a thin film. The display element sealant for solving the above problem comprises: 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) having a viscosity of 5 mPa·s or more and 30 mPa·s or less as measured by an E-type viscometer at 25°C at a rotation speed of 20 rpm, and having a number of particles having a particle size of 0.1 μm or more present in 1 mL of 10,000 or less. 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 acid-based polymer.

Description

Technical Field

[0001] This invention relates to a sealant for display elements, a method for manufacturing the same, and a display device. Background Technology

[0002] In recent years, thin display devices have become widely used. These thin display devices generally include display elements such as organic electroluminescent (hereinafter also referred to as "organic EL") elements and a sealing layer for protecting the display elements. In particular, the light-emitting layer and electrodes of organic EL elements are susceptible to degradation due to moisture or oxygen. Therefore, a method has been proposed to protect organic EL elements by layering an inorganic barrier layer containing inorganic materials and a sealing layer containing organic resin, or by alternately layering them (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2000-223264 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] Generally, the aforementioned resin-containing sealing layer is formed by coating a sealant containing a curable resin using methods such as inkjet printing and then curing it. Here, to further enhance the precision and contrast of display devices for mirrorless single-lens reflex cameras and AR (Augmented Reality) / VR (Virtual Reality) displays, research has been conducted on miniature organic EL display devices using semiconductor processes. In such display devices, to achieve even higher precision, for example, it has been studied to reduce the thickness of the sealing layer to less than 1 / 10 of its previous thickness. However, with known sealants, it is difficult to form such a very thin sealing layer, resulting in the problem of uneven film thickness or defects in the obtained sealing layer.

[0008] The object of this invention is to provide a sealant for display elements capable of forming a uniform sealing layer even in thin films, and a method for manufacturing the same. Furthermore, the object of this invention is also to provide a display device using this sealant for display elements.

[0009] Solution for solving the problem

[0010] The present invention provides the following sealant for display elements.

[0011] [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 oxetane groups in one molecule; a cationic polymerization initiator (C); and a leveling agent (D) having a viscosity of 5 mPa·s or more and 30 mPa·s or less as measured by an E-type viscometer at 25°C and 20 rpm, and having 10,000 or fewer particles with a particle size of 0.1 μm or more present per 1 mL, wherein 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.

[0012] [2] The sealant for display elements as described in [1] is inkjet ink.

[0013] The present invention provides the following display device.

[0014] [3] A display device comprising, in sequence, a display element, a first inorganic barrier layer comprising an inorganic material, a sealing layer, and a second inorganic barrier layer comprising an inorganic material, wherein the sealing layer comprises 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 oxetane groups in one molecule, and a leveling agent (D), wherein 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.

[0015] [4] The display device as described in [3], wherein the average film thickness of the sealing layer is less than 3 μm.

[0016] The present invention provides a method for manufacturing a sealant for display elements.

[0017] [5] A method for manufacturing a sealant for a display element, comprising: a step of preparing a composition comprising an epoxy compound (A) having two or more epoxy groups in one molecule, an oxetane compound (B) having one or more oxetane groups in one molecule, a cationic polymerization initiator (C), and a leveling agent (D); and a step of filtering the composition using a filter with a pore size of 0.1 μm or less, wherein 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.

[0018] The effects of the invention

[0019] The sealant for display elements according to the present invention can form a thin sealing layer and can make its film thickness uniform. Detailed Implementation

[0020] 1. Sealant for display components

[0021] 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 forming material for a layer (sealing layer) for sealing organic EL elements. Hereinafter, the case of forming a sealing layer by applying the sealant using an inkjet method, that is, using the sealant as ink for inkjet printing, will be described as an example, but the application method of the sealant is not limited to inkjet printing.

[0022] As mentioned above, it is difficult to form a thin sealing layer in known sealants. The reasons for this are as follows: Sealing layers are mostly formed using inkjet printing. Furthermore, to reduce the film thickness of the sealing layer, the diameter of the inkjet nozzle needs to be reduced, resulting in a very small amount of sealant being dispensed. However, the inventors have conducted in-depth research and found that if known sealants are to be ejected from a small-diameter nozzle, the nozzle is easily clogged due to the large particles in the sealant. In addition, even if the sealant can be ejected from the nozzle, the film thickness is uneven, making it impossible to form a uniform sealing layer, leading to a decrease in yield. On the other hand, it has also been shown that if large particles are removed from the sealant using filtration, the leveling agent is easily removed along with the large particles. If the leveling agent is removed from the sealant in this way, the sealant ejected from the nozzle cannot adequately wet and spread, and the resulting sealing layer is also prone to becoming uneven.

[0023] In contrast, the sealant of the present invention comprises: an epoxy compound (A), an oxetane compound (B), a cationic polymerization initiator (C), and a specific leveling agent (D). Furthermore, the viscosity of this sealant, measured using an E-type viscometer at 25°C and 20 rpm, is 5 mPa·s or more and 30 mPa·s or less. Moreover, the number of particles with a diameter of 0.1 μm or more present in each mL of this sealant is 10,000 or less. Therefore, it can be ejected from inkjet nozzles with small diameters. In addition, the sealant of the present invention not only has a low number of coarse particles, but also contains a leveling agent (D) selected from at least one of ester-based leveling agents, polyether-based leveling agents, and (meth)acrylic polymers. These leveling agents (D) are difficult to remove by filtration. Therefore, the sealant contains a desired amount of leveling agent (D), which facilitates sufficient wetting and spreading when forming a sealing layer, enabling the formation of a uniform sealing layer even with a thin film. Furthermore, since the viscosity of the sealant is within the aforementioned range, it is easily ejected using inkjet printing, and the ejected droplets readily and sufficiently wet and spread. Therefore, the sealant according to the present invention can form a very thin sealing layer for thin display devices. Hereinafter, the components and properties of the sealant will be described in detail.

[0024] • Epoxy compounds (A)

[0025] In this specification, the term "epoxy compound (A)" refers to a compound having two or more epoxy groups in one molecule. There are no particular limitations as long as the epoxy compound is capable of photocuring using the cationic polymerization curing agent described later. The sealant may contain only one epoxy compound (A) or may contain two or more.

[0026] The epoxy compound (A) described above can be a solid compound at 25°C or a liquid compound, but from the viewpoint of easily achieving the desired viscosity, a liquid compound is preferred. When the epoxy compound (A) is liquid at 25°C, the viscosity of the epoxy compound (A), measured using an E-type viscometer at 25°C and 20 rpm, is preferably 1 mPa·s or more and 500 mPa·s or less, more preferably 5 mPa·s or more and 100 mPa·s or less. If the viscosity of the epoxy compound (A) is within this range, the viscosity of the sealant can be easily controlled within the desired range.

[0027] The epoxy compound (A) may be an alicyclic epoxy compound, an aliphatic epoxy compound, or an aromatic epoxy compound, and is particularly preferred to be 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.

[0028] Examples of alicyclic epoxy compounds that can be the above-mentioned epoxy compound (A) include compounds having a cyclic olefin oxide structure represented by the following general formula. The so-called cyclic olefin oxide structure is a structure obtained by epoxidizing a cyclic olefin with an oxidizing agent such as a peroxide, and is a structure having an aliphatic ring and an epoxy group consisting of two carbon atoms and an oxygen atom constituting the aliphatic ring.

[0029] [Chemistry 1]

[0030]

[0031] In the above general formula, M represents an alicyclic structure, which preferably has 4 or more and 8 or less carbon atoms, more preferably 5 or 6. If the number of carbon atoms in the alicyclic structure of the cyclic olefin oxide structure is within this range, the viscosity of the sealant can be easily controlled within the desired range.

[0032] Specific examples of cycloolefin oxide structures include cyclohexene oxide and cyclopentene oxide, with cyclohexene oxide being preferred.

[0033] A molecule of an alicyclic epoxy compound may contain one cyclic olefin oxide structure (monofunctional) or two or more (polyfunctional). From the perspective of superior heat resistance, a molecule of an alicyclic epoxy compound preferably contains two or more cyclic olefin oxide structures (polyfunctional).

[0034] Examples of alicyclic epoxides having a cyclic olefin oxide structure include compounds represented by the following general formulas (A-1) to (A-3).

[0035] [Chemistry 2]

[0036]

[0037] In the above general formula (A-1), M 1 and M 2 This indicates an alicyclic structure, and as described above, the number of carbon atoms is preferably 4 or more and 8 or less, more preferably 5 or 6. X in the above general formula (A-1) 1 It can be a single bond or a linking group. Examples of linking groups include: divalent hydrocarbon groups, carbonyl groups, ether groups (ether bond), thioether groups (thioether bond), ester groups (ester bond), carbonate groups (carbonate bond), amide groups (amide bond), or groups that link multiple of them together.

[0038] Examples of divalent hydrocarbon groups include alkylene groups or divalent alicyclic hydrocarbon groups having 1 to 18 carbon atoms. 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: 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, cyclohexylene, and other divalent cycloalkylene groups (including cycloalkylene groups).

[0039] Among them, X 1 Preferably, it is a single bond or a linking group having an oxygen atom. More preferably, the linking group having an oxygen atom is -CO- (carbonyl), -O-CO-O- (carbonate group), -COO- (ester group), -O- (ether group), -CONH- (amide group), a group formed by linking multiple of these groups, or a group formed by linking one or more of these groups with one or more divalent hydrocarbon groups.

[0040] Specific examples of alicyclic epoxides represented by general formula (A-1) include the following compounds. It should be noted that in the following formulas, l is an integer from 1 to 10, and m is an integer from 1 to 30. Furthermore, R is an alkylene group having 1 to 8 carbon atoms (preferably alkylene groups having 1 to 3 carbon atoms, such as methylene, ethylene, propylene, or isopropylene). n1 and n2 are integers from 1 to 30.

[0041] [Chemistry 3]

[0042]

[0043]

[0044] Examples of commercially available alicyclic epoxy compounds represented by the above general formula (A-1) include: Celloxide2021P, Celloxide 2081, Celloxide 8000, Celloxide 8010 (all manufactured by Daicel).

[0045] On the other hand, alicyclic epoxides having a cyclic olefin oxide structure can be compounds having the structure represented by the following general formula (A-2) or general formula (A-3).

[0046] [Chemistry 4]

[0047]

[0048]

[0049] In the above general formulas (A-2) and (A-3), M 3 M 4 and M 5 This indicates an alicyclic structure, preferably with 4 or more but less than 8 carbon atoms, more preferably 5 or 6. X in the above general formula (A-3) 2 It is a single bond or a linker group. This linker group is the same as the linker group in the above general formula (A-1). In addition, in the compounds represented by general formulas (A-2) and (A-3), alkyl groups or the like may also be bonded to the carbons that constitute the alicyclic structure or epoxy group.

[0050] Examples of alicyclic epoxy compounds represented by the above general formula (A-2) or general formula (A-3) include: 3,4:7,8-diepoxybicyclo[4.3.0]nonane, limonene dioxide, etc. Examples of commercially available products of these include: THI-DE (manufactured by JX-TG Corporation), LDO (manufactured by Nagase ChemteX Corporation), etc.

[0051] On the other hand, examples of aliphatic epoxy compounds that can be epoxy compound (A) include polyglycidyl ethers containing a structure derived from aliphatic polyols or their alkyl oxide adducts. The aforementioned aliphatic polyols can be chain-like or have a partially cyclic structure (except for the aforementioned alicyclic epoxy compounds). From the viewpoint that the viscosity of the sealant can be easily controlled within a desired range, the aforementioned aliphatic polyols are preferably chain-like. Therefore, aliphatic epoxy compounds are particularly preferably diglycidyl ethers of alkyldiols or their alkyl oxide adducts.

[0052] Examples of aliphatic epoxy compounds include: diglycidyl ethers of alkyl diols with 4 to 6 carbon atoms, such as 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether; triglycidyl ethers, such as glycerol and trimethylolpropane; tetraglycidyl ether of sorbitol; hexaglycidyl ether of dipentaerythritol; diglycidyl ethers, such as polyethylene glycol and polypropylene glycol; and polyglycidyl ethers of epoxide adducts (polyether polyols), such as propylene glycol and trimethylolpropane.

[0053] Examples of commercially available aliphatic epoxy compounds include: SR-PG, SR-2EGS, SR-8EGS, SR-14BJ, SY-25L (manufactured by Sakamoto Pharmaceutical Co., Ltd.); Epogosey 2EH, Epogosey HD(D), Epogosey NPG(D), Epogosey BD(D) (manufactured by Yokkaichi Synthetic Co., Ltd.); Denacol EX-121, Denacol EX-212L, Denacol EX-214L (manufactured by Nagase ChemteX Co., Ltd.), etc.

[0054] Examples of aromatic epoxy compounds include glycidyl ethers of polyols containing aromatic rings. Examples of aromatic epoxy compounds include: 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 addition bisphenol A type epoxy resins, resorcinol type epoxy resins, biphenyl type epoxy resins, thioether type epoxy resins, diphenyl ether type epoxy resins, naphthyl type epoxy resins, phenolic varnish type epoxy resins, o-cresol phenolic varnish type epoxy resins, biphenyl phenolic varnish type epoxy resins, naphthol phenolic varnish type epoxy resins, etc.

[0055] When the epoxy compound (A) has any of the above-described structures, 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 is controlled within the desired range, and is generally preferably 400 or less. If the molecular weight of the epoxy compound (A) is 180 or more, the evaporation of the epoxy compound (A) from the sealant can be suppressed. As a result, when applying the sealant using an inkjet coating method, the composition is less likely to change, and the working environment is less likely to deteriorate. The molecular weight of the epoxy compound (A) can be determined based on its structure. Alternatively, the weight-average molecular weight can be determined using gel permeation chromatography (GPC) converted to polystyrene.

[0056] Furthermore, the surface tension of the epoxy compound (A) at 25°C (in the case of multiple epoxy compounds (A), the surface tension of each individual compound) is preferably 15 N / mm or more and 50 N / mm or less, more preferably 20 N / mm or more and 40 N / mm or less. If the surface tension of the epoxy compound (A) is within this range, the surface tension of the sealant can be easily controlled within the desired range. The aforementioned surface tension is a value measured using a surface tension meter and the Wilhelmy method.

[0057] The content of the epoxy compound (A) relative to the total amount of the sealant (in the case of multiple epoxy compounds (A), the total amount thereof) is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass or less. If the amount of epoxy compound (A) is within this range, a sealing layer can be easily and uniformly formed, and the obtained sealing layer can be easily used to protect various components.

[0058] ·Oxycyclic butane compounds (B)

[0059] The oxetane compound can be any compound having one or more oxetane groups in one molecule. It can be a solid at 25°C or a liquid, but from the viewpoint that the viscosity of the sealant can be easily controlled within the desired range, a liquid compound is preferred. When the oxetane compound (B) is liquid at 25°C, the viscosity of the oxetane compound (B) measured using an E-type viscometer at 25°C and 20 rpm is preferably 1 mPa·s to 500 mPa·s, more preferably 1 mPa·s to 300 mPa·s. If the viscosity of the oxetane compound (B) is within this range, the viscosity of the sealant can be easily controlled within the desired range.

[0060] The oxetane compound (B) is preferably a compound represented by the following general formula (B-1) or general formula (B-2). The sealant may contain only one oxetane compound (B) or may contain two or more.

[0061] [Chemistry 5]

[0062]

[0063] [Chemistry 6]

[0064]

[0065] In the above general formulas (B-1) and (B-2), Y represents an oxygen atom, a sulfur atom, or a single bond. Among them, oxygen atom is preferred.

[0066] Additionally, R 1a and R 1bThese represent fluorine atoms, alkyl groups with 1 to 6 carbon atoms, fluoroalkyl groups with 1 to 6 carbon atoms, allyl groups, aryl groups with 6 to 18 carbon atoms, furanyl groups, or ethynyl groups, respectively. m and n represent integers greater than 1 and less than 5. A molecule may contain multiple R atoms. 1a Or R 1b In this case, they can be the same or different. Additionally, adjacent R... 1a R that are adjacent to each other 1b They can form ring structures with each other.

[0067] Additionally, R in general formula (B-1) 2a The terms "(meth)acryloyl" refer to hydrogen atoms, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, aralkyl groups having 7 to 18 carbon atoms, alkyl carbonyl groups having 2 to 6 carbon atoms, alkoxy carbonyl groups having 2 to 6 carbon atoms, N-alkylcarbamoyl groups having 2 to 6 carbon atoms, or (meth)acryloyl groups. In this specification, (meth)acryloyl group refers to methacryloyl, acryloyl, and both. The same applies to (meth)allyl, (meth)acrylic acid, etc.

[0068] On the other hand, R in general formula (B-2) 2b R represents a linker base with a valence of p, where p represents 2, 3, or 4. 2b This refers to, for example, a straight-chain or branched alkylene group, a straight-chain or branched poly(alkyleneoxy) group, an aryl group, a siloxane bond, or a combination thereof, having 1 to 12 carbon atoms.

[0069] Furthermore, especially from the viewpoint that the viscosity of the sealant can be easily controlled within the desired range, the oxobutane compound is preferably a compound represented by the following general formula (B-3) or general formula (B-4).

[0070] [Chemistry 7]

[0071]

[0072] In the above general formulas (B-3) and (B-4), Y represents an oxygen atom or a sulfur atom. 1c R 1d Or R 2d The term represents hydrogen atoms, fluorine atoms, alkyl groups having 1 to 6 carbon atoms, fluoroalkyl groups having 1 to 6 carbon atoms, aryl groups having 6 to 18 carbon atoms, furanyl groups, or thiophene groups. Among these, alkyl groups having 1 to 6 carbon atoms are preferred from the viewpoint that the viscosity of the sealant is easier to control within the desired range.

[0073] R 2cThe atom is 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 alkyl carbonyl group having 2 to 6 carbon atoms, an alkoxy carbonyl group having 2 to 6 carbon atoms, an N-alkylcarbamoyl group having 2 to 6 carbon atoms, or a (meth)acryloyl group. Among these, from the viewpoint of reducing the viscosity of the composition, an alkyl group having 1 to 10 carbon atoms is more preferred.

[0074] Examples of compounds represented by general formula (B-3) include: 3-ethyl-3-hydroxymethyloxetane, 3-(methyl)allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetane-butylmethoxy)methylbenzene, 4-fluoro-[1-(3-ethyl-3-oxetane-butylmethoxy)methyl]benzene, 4-methoxy-[1-(3-ethyl-3-oxetane-butylmethoxy)methyl]benzene, [1-(3-ethyl-3-oxetane-butylmethoxy)ethyl]phenyl ether, isobutoxymethyl(3-ethyl-3-oxetane-butylmethyl) ether, isoborneol oxide Examples of compounds represented by general formula (B-4) include 3,3'-(oxybis(methylene)bis(3-ethyl-3-oxetane)methyl) ether, isobornyl(3-ethyl-3-oxetane)methyl) ether, 2-ethylhexyl(3-ethyl-3-oxetane)methyl) ether, ethyl diethylene glycol(3-ethyl-3-oxetane)methyl) ether, dicyclopentadiene(3-ethyl-3-oxetane)methyl) ether, 3-methacryloyloxymethyl-3-ethyloxetane, 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, etc., with 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane being particularly preferred. Additionally, examples of compounds represented by general formula (B-4) include 3,3'-(oxybis(methylene)bis(3-ethyloxetane)).

[0075] Examples of commercially available oxetane compounds include: OXT-221, OXT-121, OXT-212 (all manufactured by Toa Synthetic Co., Ltd.), OXBP, and HBOX (all manufactured by Ube Industries, Ltd.).

[0076] The molecular weight of the aforementioned oxetane compound (B) is preferably 180 or higher. If the molecular weight of the oxetane compound (B) is 180 or higher, it is less likely to volatilize within the inkjet printer, and the composition of the sealant is less likely to change. From the viewpoint of suppressing the volatilization of the oxetane compound, the molecular weight of the oxetane compound (B) is preferably 190 or higher, more preferably 200 or higher. The upper limit of the molecular weight is sufficient as long as the viscosity of the sealant is within the desired range, and is generally preferably 400 or lower. The molecular weight can be determined based on the structure, or the weight-average molecular weight can be determined using the same method as for the aforementioned epoxy compound (A).

[0077] Furthermore, the surface tension of the oxetane compound (B) at 25°C (in the case of multiple oxetane compounds (B), the surface tension of each individual compound) is preferably 15 N / mm or more and 50 N / mm or less, more preferably 20 N / mm or more and 45 N / mm or less. If the surface tension of the oxetane compound (B) is within this range, the surface tension of the sealant can be easily controlled within the desired range. The aforementioned surface tension is a value measured using a surface tension meter and the Wilhelmie method.

[0078] The content of the aforementioned oxetane compound (B) relative to the total amount of the sealant (in the case of multiple oxetane compounds (B), it is their total amount) is preferably 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 75% by mass or less. If the amount of oxetane compound (B) is within this range, a sealing layer can be easily and uniformly formed, and the obtained sealing layer can be easily used to protect various components.

[0079] • Cationic polymerization initiator (C)

[0080] The cationic polymerization initiator (C) is preferably a compound that generates an active species capable of initiating cationic polymerization by irradiation with active rays such as ultraviolet light (e.g., UV light). The sealant may contain only one cationic polymerization initiator (C) or may contain two or more.

[0081] Examples of cationic polymerization initiators (C) include aromatic sulfonium salts, aromatic iodinated sulfonium salts, aromatic diazonium salts, and aromatic ammonium salts. Their anionic moiety is preferably BF4. - PX6 - (X is fluorine or fluoroalkyl), SbF6 - or BX4 - (X is a phenyl group that has been substituted with at least two fluorine or trifluoromethyl groups).

[0082] Examples of the aforementioned aromatic sulfonium salts include: bis[4-(diphenylsulfonyl)phenyl]sulfide bis(hexafluorophosphate), bis[4-(diphenylsulfonyl)phenyl]sulfide bis(hexafluoroantimonate), bis[4-(diphenylsulfonyl)phenyl]sulfide bis(tetrafluoroborate), bis[4-(diphenylsulfonyl)phenyl]sulfide tetra(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, etc.

[0083] Examples of the above-mentioned aromatic iodine salts include: diphenyliodohexafluorophosphate, diphenyliodohexafluoroantimonate, diphenyliodotetrafluoroborate, diphenyliodotetra(pentafluorophenyl)borate, bis(dodecylphenyl)iodohexafluorophosphate, bis(dodecylphenyl)iodohexafluoroantimonate, bis(dodecylphenyl)iodotetrafluoroborate, bis(dodecylphenyl)iodotetra(pentafluorophenyl)borate, etc.

[0084] Examples of the above-mentioned aromatic diazonium salts include: phenyldiazo hexafluorophosphate, phenyldiazo hexafluoroantimonate, phenyldiazo tetrafluoroborate, phenyldiazo tetra(pentafluorophenyl)borate, etc.

[0085] Examples of the aromatic ammonium salts mentioned above include: 1-benzyl-2-cyanopyridine hexafluorophosphate, 1-benzyl-2-cyanopyridine hexafluoroantimonate, etc.

[0086] Examples of commercially available cationic polymerization initiators (C) include: Irgacure 250, Irgacure 270, Irgacure 290 (manufactured by BASF); CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-210K, CPI-310B, CPI-310FG, CPI-400PG (manufactured by San-Apro); SP-150, SP-170, SP-171, SP-056, SP-066, SP-130, SP-140, SP-601, SP-606, SP-701 (manufactured by ADEKA). Among them, preferred matte salts include 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.

[0087] The content of the cationic polymerization initiator (C) relative to the total amount of the sealant (in the case of multiple cationic polymerization initiators (C), the total amount thereof) is preferably 0.5% by mass or more and 2.5% by mass or less, more preferably 0.8% by mass or more and 1.3% by mass or less. If the amount of cationic polymerization initiator (C) is within this range, the photocurability of the sealant is more likely to be good.

[0088] Leveling agent (D)

[0089] A leveling agent is a compound used to improve the wettability of a sealant on a substrate by adjusting the surface tension of the sealant coating, thereby improving the flatness of the sealant layer by increasing the flowability of the coating or improving defoaming properties. 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 leveling agent (D) or may contain two or more leveling agents (D).

[0090] As described above, the number of particles with a diameter of 0.1 μm or larger present in each 1 mL of the sealant of the present invention is less than 10,000. Filtration is performed during the manufacture of such a sealant. Here, when removing coarse particles from the sealant or its raw materials by filtration, a filter made of polytetrafluoroethylene (PTFE) is generally used. However, ester-based leveling agents, ether-based leveling agents, and (meth)acrylic polymers are difficult to filter using the aforementioned filter.

[0091] Examples of ester-based leveling agents include polyester-modified acryloyl-containing polydimethylsiloxanes, polyester-modified polydimethylsiloxanes, and polyester polyols. Among these, polyester-modified polydimethylsiloxanes are preferred. The polyester-modified polydimethylsiloxane simply needs to be a compound having a polydimethylsiloxane backbone and polyester chains bonded to that backbone. The polyester-modified polydimethylsiloxane can be commercially available, examples of which include BYK-310 and BYK-370 (both manufactured by BYK-Chemie Japan).

[0092] Examples of polyether-based leveling agents include: cellulose ethers; pullulan; polyethylene glycol; silicone-modified polyether polydimethylsiloxanes, polyether-modified siloxanes, polyether ester-modified hydroxyl-containing polydimethylsiloxanes, polyether-modified acryloyl-containing polydimethylsiloxanes, etc.; polyglycerols; polyether polyols, polyoxyethylene-polyoxypropylene condensates, polyoxyethylene alkylphenyl ethers, lauryl alcohol alkoxides, etc., and alkyl ether derivatives; alkyl ether sulfates, etc. Among these, polyether-modified polydimethylsiloxanes are preferred. Polyether-modified polydimethylsiloxanes are compounds that have a polydimethylsiloxane backbone and polyether chains bonded to that backbone. The polyether-modified polydimethylsiloxane is available as a commercially available product, examples of which include BYK-333, BYK-330, BYK-302, and BYK-UV3500 (all manufactured by BYK-Chemie Japan).

[0093] (Meth)acrylic polymers are, for example, polymers obtained by homopolymerization or copolymerization of monomers having (meth)acryloyl groups (also referred to as "polyacrylates" in this specification). Examples of monomers having (meth)acryloyl groups include: (meth)acrylates having hydroxyl groups, (meth)acrylates having epoxides such as ethylene oxide, etc. (Meth)acrylic polymers are preferably structures containing monomers derived from such hydrophilic groups.

[0094] (Meth)acrylic acid polymers are also commercially available. Examples 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-Chemie Japan).

[0095] The content of the leveling agent (D) relative to the total amount of the sealant (in the case of multiple leveling agents (D), the total amount thereof) is preferably 0.01% by mass or more and 1% by mass or less, more preferably 0.1% by mass or more and 0.5% by mass or less. If the amount of leveling agent (D) is within this range, the coating film is easier to make smooth when the sealant is applied, and a uniform sealing layer is more easily obtained.

[0096] Other ingredients

[0097] Without prejudice to the purpose and effects of the present invention, the sealant may further contain components other than those described above. Examples of other components include sensitizers, ultraviolet absorbers, etc.

[0098] Sensers are compounds that enhance the generation efficiency of active species based on cationic polymerization initiators (C) and promote the curing reaction of sealants. Examples of sensers include: thioxanthone compounds such as 2,4-diethylthioxanthone; benzophenone compounds such as 2,2-dimethoxy-1,2-diphenylethane-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.

[0099] The content of the sensitizer (the total amount of multiple sensitizers) relative to the total amount of the sealant is preferably 0.1% by mass or more and 2.5% by mass or less, more preferably 0.5% by mass or more and 2% by mass or less. When the amount of sensitizer is within this range, the curing properties of the sealant become good.

[0100] Examples of ultraviolet absorbers include benzotriazole compounds, benzophenone compounds, triazine compounds, and cyanoacrylate compounds.

[0101] Examples of the aforementioned benzotriazole compounds include: 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2,2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2-hydroxy-5-methylphenyl)benzotriazole, and 2-(2'-hydroxy-4'-n-octyloxyphenyl)benzotriazole. Preferred examples include: 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 examples include 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol and 2-(2-hydroxy-5-methylphenyl)benzotriazole, and even more preferred examples include 2-(2-hydroxy-5-methylphenyl)benzotriazole.

[0102] Commercially available products can also be used as benzotriazole compounds. Examples of commercially available benzotriazole compounds include: Tinuvin 234 (2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, manufactured by BASF Japan), KEMISORB 71 (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.).

[0103] Examples of the aforementioned benzophenone compounds include: [2-hydroxy-4-(octyloxy)phenyl](phenyl) methyl ketone, 2-hydroxy-4-n-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfonic acid. Benzyl ketone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone trihydrate, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, and 2-hydroxy-4-(2-hydroxy-3-methacryloyloxy)propoxybenzophenone. Preferably, [2-hydroxy-4-(octyloxy)phenyl](phenyl) ketone and 2-hydroxy-4-n-octyloxybenzophenone are examples. More preferably, 2-hydroxy-4-n-octyloxybenzophenone is an example.

[0104] Commercially available products can also be used as benzophenone compounds. Examples of commercially available benzophenone compounds include: KEMISORB12 (2-hydroxy-4-n-octyloxybenzophenone, manufactured by Chemipro Chemical Co., Ltd.) and ADEKA STAB1413 ([2-hydroxy-4-(octyloxy)phenyl](phenyl) benzophenone, manufactured by ADEKA Co., Ltd.).

[0105] Examples of the triazine compounds mentioned above include 2-[4,6-bis(2,4-dimethylyl)-1,3,5-triazine-2-yl]-5-octyloxyphenol and 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, with 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine being a preferred example.

[0106] Commercially available products can also be used as triazine compounds. Examples of commercially available triazine compounds include KEMISORB102 (2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, manufactured by Chemipro Chemicals).

[0107] Examples of the aforementioned cyanoacrylate compounds include, for instance, ethyl-2-cyano-3-(3',4'-methylenedioxyphenyl)acrylate.

[0108] In the above, benzotriazole compounds, benzophenone compounds, and triazine compounds are preferred, more preferably benzotriazole compounds and benzophenone compounds, and even more preferably benzotriazole compounds or benzophenone compounds.

[0109] Furthermore, the sealant preferably contains a small amount of components that could potentially affect the display element, and particularly preferably a small amount of organic solvents. The amount of organic solvent relative to the total amount of the sealant is preferably less than 0.05% by mass, more preferably less than 0.01% by mass, and even more preferably substantially non-existent.

[0110] • Properties of sealants

[0111] The viscosity of the aforementioned sealant, measured using an E-type viscometer at 25°C and 20 rpm, is 5 mPa·s or higher and 30 mPa·s or lower. As described above, if the sealant's viscosity is within this range, it is not only easy to eject the sealant from the inkjet nozzle, but the coated droplets also easily wet and spread, resulting in a smooth sealing layer. This viscosity is preferably 5 mPa·s or higher and 50 mPa·s or lower, more preferably 8 mPa·s or higher and 30 mPa·s or lower.

[0112] Furthermore, in this sealant, the number of particles with a diameter of 0.1 μm or larger present in each 1 mL is 10,000 or less. As described above, if the number of such particles is 10,000 or less, the sealant can be ejected from a small-diameter inkjet nozzle. Additionally, when forming a thin film-thickness sealant layer, the sealant layer tends to become flat. The number of such particles is more preferably 8,000 or less, and even more preferably 6,000 or less. It should be noted that the number of particles with a diameter of 0.1 μm or larger can be determined using a liquid 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.

[0113] The surface tension of the sealant at 25°C is preferably 25 N / mm or higher and 38 N / mm or lower, more preferably 28 N / mm or higher and 35 N / mm or lower. If the surface tension of the sealant is within this range, it will easily wet and spread during application. It should be noted that the surface tension of the sealant can be measured using a surface tension meter and the Wilhelmie method.

[0114] • Method for manufacturing sealant

[0115] There are no particular restrictions on the manufacturing method of the above-mentioned sealant, as long as it can be prepared by having a particle size of 0.1 μm or larger of 10,000 or less, and the sealant contains an epoxy compound (A), an oxetane compound (B), a cationic polymerization initiator (C), and a leveling agent (D).

[0116] For example, the composition can be prepared by performing a step of preparing the composition and a step of filtering the composition using a filter with a pore size of less than 0.1 μm. The composition comprises the above-mentioned epoxy compound (A), the above-mentioned oxetane compound (B), the above-mentioned cationic polymerization initiator (C), and the above-mentioned leveling agent (D). 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 these leveling agents (D), the leveling agent (D) is not easily removed by filtration, and a sufficient amount of leveling agent (D) can be contained in the prepared sealant.

[0117] Furthermore, filtration is preferably performed using a capsule-type cartridge filter with a pore size of 0.1 μm or less, under pressure within a glove box, at a maximum operating pressure of 0.39 MPa (25°C). Moreover, this filtration can be performed multiple times, typically more than once and less than five times.

[0118] Furthermore, the method for manufacturing the sealant is not limited to the method described above. For example, each component may be filtered separately and then mixed. However, impurities (large particles) may be introduced during mixing. Therefore, it is more preferable to mix all components and then filter them as described above.

[0119] 2. Display device

[0120] The present invention also provides a display device having a sealing layer formed using the above-described sealant. The structure of the display device is not particularly limited; for example, it can be configured such that a display element, a first inorganic barrier layer comprising an inorganic material, a sealing layer, and a second inorganic barrier layer comprising an inorganic material are sequentially formed. However, the structure of the display device is not limited to this structure; for example, the second inorganic barrier layer may not be formed. Furthermore, other structures may be included as needed.

[0121] There are no particular restrictions on the type of display element in this display device; it can be any known display element that requires sealing. Organic EL elements can be cited as an example of a display element.

[0122] Furthermore, the first and second inorganic barrier layers are preferably composed of films containing inorganic materials (hereinafter also referred to as "inorganic films") that have water vapor barrier and oxygen barrier properties. The first and second inorganic barrier layers may each be composed of a single inorganic film, or two or more inorganic films. Examples of inorganic materials constituting the inorganic films 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 can be formed using methods such as resistance heating evaporation, electron beam evaporation, reactive evaporation, atomic layer deposition, ion plating, and sputtering.

[0123] The average film thickness of the first inorganic barrier layer and the second inorganic barrier layer is preferably 0.1 μm or more and 100 μm or less, and more preferably 0.1 μm or more and 100 μm or less.

[0124] On the other hand, the sealing layer can be a film formed using the aforementioned sealant, i.e., a cured product of the aforementioned sealant. There are no particular limitations on the method of forming the sealing layer, but it is preferable to form a film by applying and curing it using a known coating method.

[0125] The application method of the sealant is selected according to the desired film thickness, but inkjet printing is preferred. As described above, the sealant of the present invention can also be ejected from a small-diameter inkjet nozzle. Furthermore, the inkjet printing method has the advantage of enabling a thinner film thickness for the sealing layer. When applying the sealant using inkjet printing, the amount of liquid ejected from the nozzle is preferably 0.5 pL or more and about 10 pL or less, more preferably 2 pL or more and 5 pL or less.

[0126] Furthermore, the curing method for the sealant coating is preferably photocuring. The light source used for photocuring is appropriately selected based on the absorption wavelength of the cationic polymerization initiator. The wavelength of the irradiated light is preferably 350 nm to 450 nm, more preferably 395 nm to 405 nm. Examples of light sources include xenon lamps, carbon arc lamps, and LED (light-emitting diode) lamps (e.g., UV-LEDs), among which LEDs are more preferred. Additionally, the cumulative light intensity can be set to, for example, 1000 mJ / cm². 2 ~20000mJ / cm 2 It should be noted that, depending on the needs, heating can also be performed before, during, or after light irradiation.

[0127] The average film thickness of the sealing layer is preferably 0.1 μm or more and 5 μm or less, more preferably 0.1 μm or more and 3 μm or less, and more preferably 0.3 μm or more and 1 μm or less. If the average film thickness of the sealing layer is 0.3 μm or more, the sealing layer can easily become uniform with the sealant, and the sealing performance of the display element becomes better. On the other hand, if the average film thickness of the sealing layer is 1 μm or less, the overall film thickness of the display device can be reduced.

[0128] Example

[0129] The present invention will now be described with reference to embodiments. The scope of the present invention is not to be limited by the embodiments.

[0130] 1. Preparation of sealant

[0131] (1) Preparation of materials

[0132] In the embodiments and comparative examples, the following materials were used.

[0133] [Epoxy compound (A)]

[0134] •CEL2021P: The compound represented by the following formula (Celloxide 2021P, manufactured by Celec, molecular weight 252, viscosity at 25°C: 280 mPa·s (E-type viscometer, 20 rpm), surface tension at 25°C: 47 N / mm)

[0135] [Chemistry 8]

[0136]

[0137] •CEL8000: The compound represented by the following formula (Celloxide 8000, manufactured by Celec, molecular weight 194, viscosity at 25°C: 60 mPa·s (E-type viscometer, 20 rpm), surface tension at 25°C: 45.5 N / mm).

[0138] [Chemistry 9]

[0139]

[0140] •SR-PG: Aliphatic epoxy compound represented by the following formula (SR-PG, manufactured by Sakamoto Pharmaceutical Co., Ltd., viscosity at 25°C: 15 mPa·s (E-type viscometer, 20 rpm), surface tension at 25°C: 40 N / mm)

[0141] [Chemistry 10]

[0142]

[0143] [Oxycyclic butane compound (B)]

[0144] • OXT-221: 3,3'-(oxybis(methylene)bis(3-ethyloxetane) (OXT-221, manufactured by Toa Gosei Corporation, viscosity at 25°C: 12 mPa·s (E-type viscometer, 20 rpm), surface tension at 25°C: 34.5 N / mm)

[0145] [Catonic polymerization initiator (C)]

[0146] • CPI-210K (manufactured by San-Apro)

[0147] [Leveling agent (D)]

[0148] • BYK310: Polyester-modified polydimethylsiloxane (BYK-310, manufactured by BYK Chemical Company)

[0149] • BYK350: Polyacrylate (BYK-350, manufactured by BYK Chemical Company)

[0150] • BYK322: Arane-modified polymethylalkylsiloxane (BYK-322, manufactured by BYK Chemical Company)

[0151] (2) Preparation of sealant

[0152] (Examples 1 to 4, and Comparative Examples 2 and 3)

[0153] Epoxy compound (A), oxetane compound (B), cationic polymerization initiator (C), and leveling agent (D) were added to a flask and mixed according to the compositions (feed ratios) shown in Table 1. The mixture was stirred until no powder was visible in the resulting mixture. Then, it was filtered 20 times under pressure in a glove box using a capsule-type filter with a pore size (mesh size) of 0.1 μm.

[0154] (Comparative Example 1)

[0155] The epoxy compound (A), oxetane compound (B), cationic polymerization initiator (C), and leveling agent (D) were added to a flask and mixed as shown in Table 1. The mixture was stirred until no powder was visible in the resulting mixture. Then, it was filtered 20 times under pressure in a glove box using a capsule-type filter with a pore size (mesh size) of 0.5 μm.

[0156] (3) Viscosity determination

[0157] The viscosity of the sealants prepared in each example and comparative example at 25°C was determined using an E-type viscometer (20 rpm). The measured viscosities were evaluated as follows. The results are shown in Table 1.

[0158] ○: The above viscosity is above 5 mPa·s and below 30 mPa·s.

[0159] ×: The above viscosity is less than 5 mPa·s or greater than 30 mPa·s

[0160] (4) Evaluation of the number of particles (particle count)

[0161] The number of particles with a diameter of 0.1 μm or larger present per 1 mL of the sealants prepared in the various examples and comparative examples was determined using a KS-42A liquid particle sensor. The measured values ​​were evaluated as follows. The results are shown in Table 1.

[0162] ○: The number of particles with a diameter greater than 0.1 μm is less than 10,000 per mL.

[0163] ×: The number of particles with a diameter greater than 0.1 μm exceeds 10,000 per mL.

[0164] 3. Evaluation

[0165] For each sealant, the changes in surface tension before and after filtration during the preparation process described above, the continuous coating properties based on the inkjet printing device, and the wetting and spreading properties were evaluated. The results are shown in Table 1.

[0166] (1) Change in surface tension before and after filtration

[0167] In the preparation of the above-mentioned sealant, the surface tension before and after filtration was measured using a surface tension meter and the Wilhelmie method. The obtained values ​​were evaluated according to the following criteria.

[0168] ○: The change in surface tension before and after filtration is less than 0.5 N / mm.

[0169] ×: The change in surface tension before and after filtration is greater than 0.5 N / mm.

[0170] (2) Continuous coating properties

[0171] The sealants of the above-described embodiments and comparative examples were sprayed using an inkjet unit DMP-2831 (manufactured by Fujifilm Dimatix) and an inkjet head SAMBA G3L (volume: 2.4 pL). More specifically, 1000 drops were sprayed at 500 μm intervals onto a 50 mm × 50 mm alkali-free glass surface, and the nozzle was left to stand for 3 hours at 23°C without spraying. Another 1000 drops were sprayed, and the nozzle was then left to stand for 3 hours. This cycle was repeated three times, and the number of drops in the first cycle was compared with the number of drops in the third cycle. The results were then evaluated according to the following criteria.

[0172] ○: The ratio of the number of droplets in the third cycle to the initial number of droplets exceeds 90%.

[0173] ×: The ratio of the number of droplets in the third cycle to the initial number of droplets is less than 90%.

[0174] (3) Wetting and spreading properties

[0175] The sealants of the embodiments and comparative examples described above were ejected onto silicon wafers using an inkjet printer, DMP-2831 (manufactured by Fujifilm Dimatix), and a SAMBA G3L inkjet head (volume: 2.4 pL). The droplet diameters 30 seconds and 3 minutes after ejection were then measured using a scanning white light interference microscope. Evaluation was performed according to the following criteria.

[0176] ○: The droplet diameter 3 minutes after ejection is more than twice the droplet diameter 30 seconds after ejection.

[0177] ×: The droplet diameter 3 minutes after ejection is less than 1 times the droplet diameter 30 seconds after ejection.

[0178] [Table 1]

[0179]

[0180] As shown in Table 1 above, in sealants with more than 10,000 particles larger than 0.1 μm in diameter per 1 mL, continuous coating is poor, causing nozzle clogging and making it difficult to form a uniform sealing layer (Comparative Example 1). Furthermore, in sealants with viscosity outside the specified range, wetting and spreading properties are low, making it difficult to form a uniform sealing layer (Comparative Example 2). In Comparative Example 3, an aralkyl-modified polymethylalkylsiloxane was used to prepare the sealant. However, in this case, the change in surface tension caused by filtration was large, resulting in poor wetting and spreading properties. It can be assumed that the leveling agent (D) was removed by filtration.

[0181] In contrast, a sealant comprising an epoxy compound (A), an oxetane compound (B), a cationic polymerization initiator (C), and a leveling agent comprising a polyester or (meth)acrylic polymer (D), and having a specified viscosity and a particle size of 0.1 μm or more with a particle number of 10,000 or less, exhibits good continuous coatability and wetting spreadability, and is capable of forming a uniform sealing layer (Examples 1 to 4).

[0182] This application claims priority based on Japanese Patent Application No. 2024-047915, filed on March 25, 2024. The entire contents of that application are incorporated herein by reference.

[0183] Industrial availability

[0184] The sealant according to the present invention can be applied even from nozzles with small opening diameters, forming a thin sealing layer. Furthermore, the resulting sealing layer is less prone to unevenness. Therefore, it is very useful in the manufacture of various display devices.

Claims

1. A sealant for a display element, comprising: An epoxy compound (A) having two or more epoxy groups in one molecule; Oxycyclic butane compound (B) having one or more oxycyclic butyl groups in one molecule; Cationic polymerization initiator (C); and Leveling agent (D) The viscosity measured using a type E viscometer at 25°C and 20 rpm was above 5 mPa·s and below 30 mPa·s. The number of particles with a diameter greater than 0.1 μm present in each 1 mL is less than 10,000. The leveling agent (D) is selected from at least one group consisting of ester-based leveling agents, polyether-based leveling agents, and (meth)acrylic polymers.

2. The sealant for display elements as described in claim 1, wherein it is inkjet ink.

3. A display device comprising, in sequence: Display components, The first inorganic barrier layer containing inorganic materials, Sealing layer, and A second inorganic barrier layer containing inorganic materials. The sealing layer comprises 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 oxetane groups in one molecule, and a leveling agent (D). The leveling agent (D) is selected from at least one group consisting of ester-based leveling agents, polyether-based leveling agents, and (meth)acrylic polymers.

4. The display device as claimed in claim 3, wherein, The average film thickness of the sealing layer is less than 3 μm.

5. A method for manufacturing a sealant for a display element, comprising: The step of preparing a composition, said composition comprising an epoxy compound (A) having two or more epoxy groups in one molecule, an oxetane compound (B) having one or more oxetane groups in one molecule, a cationic polymerization initiator (C), and a leveling agent (D); and The step of filtering the composition using a filter with a pore size of less than 0.1 μm. The leveling agent (D) is selected from at least one group consisting of ester-based leveling agents, polyether-based leveling agents, and (meth)acrylic polymers.

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