Display element sealant, cured product thereof, and display device

Abstract

The present invention provides a sealant for a display element, comprising a polymerizable compound and a curing agent. The polymerizable compound comprises a component (A) and a component (B), wherein the component (A) is a difunctional or higher-functional (meth)acrylate having an alicyclic structure, and the component (B) is a difunctional (meth)acrylate having a chain structure. The content of the component (A) is 60 parts by mass or less per 100 parts by mass of the total of the components (A) and (B). The content of the component (C) in the sealant for a display element is 1 part by mass or less per 100 parts by mass of the polymerizable compound, and the component (C) is a monofunctional (meth)acrylate.

Description

Technical Field

[0001] The present invention relates to a sealant for a display element, a cured product thereof, and a display device. Background Art

[0002] In the field of display devices, research on improving the properties of sealants has been ongoing. Hereinafter, an organic EL display device will be used as an example for explanation.

[0003] Organic EL elements are increasingly used in displays, lighting devices, and the like due to their low power consumption. However, organic EL elements are easily degraded by moisture and oxygen in the atmosphere and are therefore sealed with various sealing members before use. To achieve practical application, it is desirable to improve the durability of these sealing members against moisture and oxygen.

[0004] As a method for sealing an organic EL element, for example, a method is adopted in which a first layer of an inorganic material film is coated on the organic EL element, a resin layer is formed thereon, and a second layer of an inorganic material film is further coated. Examples of methods for coating with the inorganic material film include methods of forming an inorganic material film composed of silicon nitride or silicon oxide by sputtering, electron cyclotron resonance (ECR) plasma CVD, or the like.

[0005] As a technology for using an acrylic resin as the above-mentioned resin layer, there is a technology described in Patent Document 1 (International Publication No. 2019 / 82996). In the same document, it is described that a non-cyclic alkanediol di(meth)acrylate having more than 6 carbon atoms and a cyclic monomer containing a cyclic monofunctional (meth)acrylate and a cyclic bifunctional (meth)acrylate are used in combination in a sealant for an organic electroluminescent display element. According to the same document, a sealant having excellent discharge properties when using an inkjet and excellent reliability of the resulting organic EL element can be obtained.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: International Publication No. 2019 / 82996 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] The present inventors have studied the use of acrylic resins in sealing layers of display devices and have discovered that resin layers produced using acrylic resins sometimes have low plasma resistance. Consequently, when an inorganic material film is formed on the resin layer using methods such as plasma CVD, damage to the resin layer can cause pinholes in the inorganic material film or the resin layer can peel from the substrate.

[0011] Furthermore, the present inventors studied the technology described in the above patent document and found that, in Patent Document 1, since the glass transition temperature of the cured body is high, it is expected that there may be cases where it is not suitable for devices requiring flexibility, and there is room for improvement in this regard.

[0012] The present invention provides a sealing agent for a display element that has excellent plasma resistance and can be stably applied by an inkjet method and has both viscosity and a low dielectric constant.

[0013] Methods for solving problems

[0014] According to the present invention, there are provided the following sealing agent for display elements, cured product, and display device.

[0015] [1] A sealant for a display element, comprising a polymerizable compound and a curing agent,

[0016] The polymerizable compound comprises the following components (A) and (B):

[0017] (A) a difunctional or higher-functional (meth)acrylate having an alicyclic structure,

[0018] (B) a bifunctional (meth)acrylate having a chain structure,

[0019] The content of the component (A) is 60 parts by mass or less relative to 100 parts by mass of the total of the component (A) and the component (B).

[0020] The content of the component (C) in the sealing agent for display elements is 1 part by mass or less based on 100 parts by mass of the polymerizable compound, and the component (C) is a monofunctional (meth)acrylate.

[0021] [2] The sealing agent for a display element according to [1], wherein the component (A) contains dimethyloltricyclodecane di(meth)acrylate.

[0022] [3] The sealant for a display element according to [1] or [2], wherein the component (B) is one or more (meth)acrylates selected from the group consisting of 1,12-dodecanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate.

[0023] [4] The display element sealant according to any one of [1] to [3], which is used for sealing an organic EL display element.

[0024] [5] A cured product obtained by curing the sealant for a display element according to any one of [1] to [4].

[0025] [6] A display device comprising: a substrate, a display element disposed on the substrate, and a sealing layer covering the display element;

[0026] The sealing layer is composed of a cured product of the sealant for a display element according to any one of [1] to [4].

[0027] Effects of the Invention

[0028] According to the present invention, it is possible to provide a sealing agent for a display element that has excellent plasma resistance and can be stably applied by an inkjet method, and that has both viscosity and a low dielectric constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] [ Figure 1 ] is a cross-sectional view showing an example of the structure of an organic EL display device in an embodiment. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described using the accompanying drawings. It should be noted that, in all the accompanying drawings, common reference numerals are assigned to the same constituent elements, and descriptions are appropriately omitted. In addition, in the present embodiment, for each component, one type may be used, or two or more types may be used in combination. In addition, "to" indicating a numerical range indicates above or below, including both an upper limit and a lower limit.

[0031] (Sealants for display devices)

[0032] In this embodiment, the sealant for display elements (hereinafter sometimes referred to as "sealant") is a composition used for sealing elements, and contains a polymerizable compound and a curing agent. The polymerizable compound contains the following components (A) and (B):

[0033] (A) a difunctional or higher-functional (meth)acrylate having an alicyclic structure;

[0034] (B) a bifunctional (meth)acrylate having a chain structure,

[0035] The content of component (A) is 60 parts by mass or less per 100 parts by mass of the total of components (A) and (B). The content of component (C): monofunctional (meth)acrylate in the display element sealant is 1 part by mass or less per 100 parts by mass of the polymerizable compound.

[0036] Here, the term "(meth)acrylate" means at least one of acrylate and methacrylate. Also, the term "(meth)acrylic acid" means at least one of acrylic acid and methacrylic acid.

[0037] (Polymerizable compound)

[0038] The polymerizable compound may be any compound having a polymerizable functional group, and is preferably a compound having a radical polymerizable functional group. The polymerizable compound contains the above-mentioned component (A) and component (B).

[0039] (ingredient (A))

[0040] Component (A) is a (meth)acrylate having a difunctional or higher functional group and an alicyclic structure. Specifically, component (A) is a (meth)acrylate having an alicyclic structure in its molecular structure and having two or more (meth)acryloyl groups. From the perspective of improving strength, a (meth)acrylate having two (meth)acryloyl groups is preferred.

[0041] More specifically, component (A) has an alicyclic hydrocarbon structure in its molecular structure. From the viewpoint of improving heat resistance, the number of carbon atoms in the alicyclic hydrocarbon structure is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more. In addition, it is preferably 14 or less, more preferably 12 or less, and even more preferably 10 or less.

[0042] The alicyclic hydrocarbon structure may be a saturated hydrocarbon structure or an unsaturated hydrocarbon structure. From the viewpoint of improving heat resistance, the alicyclic hydrocarbon structure is preferably a saturated hydrocarbon structure.

[0043] The alicyclic hydrocarbon structure may be a monocyclic hydrocarbon structure, or a polycyclic hydrocarbon structure such as a condensed ring hydrocarbon structure or a bridged ring hydrocarbon structure. Component (A) may contain a group containing such an alicyclic hydrocarbon structure in its molecular structure, and preferably contains a divalent group containing an alicyclic hydrocarbon structure.

[0044] Specific examples of the monocyclic hydrocarbon group include groups having a cycloalkane structure such as cyclohexylene and cyclohexyl; and groups having a cycloolefin skeleton such as cyclodecatrienediyl and cyclodecatrienyl.

[0045] Specific examples of the polycyclic hydrocarbon group include: groups having a dicyclopentadiene skeleton, such as tricyclodecanediyl, dicyclopentyl, and dicyclopentenyl; groups having a norbornane skeleton, such as norbornanediyl, isobornanediyl, norbornyl, and isobornyl; and groups having an adamantane skeleton, such as adamantanediyl and adamantyl.

[0046] From the viewpoint of improving plasma resistance and low moisture permeability, the cyclic hydrocarbon group in the component (A) is preferably a group having a dicyclopentadiene skeleton.

[0047] From the viewpoint of improving plasma resistance and low moisture permeability, component (A) contains tricyclodecane dimethanol di(meth)acrylate, and component (A) is preferably tricyclodecane dimethanol di(meth)acrylate.

[0048] From the viewpoint of improving heat resistance, the content of component (A) in the sealant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, relative to 100 parts by mass of the polymerizable compound.

[0049] From the viewpoint of improving inkjet coating properties, the content of component (A) in the sealant is preferably 60 parts by mass or less, more preferably 58 parts by mass or less, and even more preferably 56 parts by mass or less, based on 100 parts by mass of the polymerizable compound.

[0050] (Component (B))

[0051] Component (B) is a bifunctional (meth)acrylate having a chain structure. Specifically, component (B) is a (meth)acrylate having a chain structure in its molecular structure and having two or more (meth)acryloyl groups. From the perspective of improving strength, a (meth)acrylate having two (meth)acryloyl groups is preferred.

[0052] Specific examples of the component (B) include alkylene glycol di(meth)acrylates and (poly)alkylene glycol di(meth)acrylates.

[0053] In the component (B), the chain structure may be a linear structure or a branched structure.

[0054] From the perspective of improving inkjet coating properties, the chain structure preferably contains a linear or branched divalent hydrocarbon group. From the perspective of monomer availability, the number of carbon atoms in the divalent hydrocarbon group is, for example, 1 or more, preferably 2 or more, and more preferably 4 or more. From the perspective of improving heat resistance, the number of carbon atoms in the divalent hydrocarbon group is preferably 20 or less, and more preferably 14 or less.

[0055] More specifically, component (B) includes 1,6-hexanediol diacrylate (e.g., A-HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,9-nonanediol diacrylate (e.g., A-NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Light Acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd.), 1,10-decanediol diacrylate (e.g., A-DOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), neopentyl glycol diacrylate (e.g., A-NPG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; Light Acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd.), ethylene glycol diacrylate (e.g., SR206NS, manufactured by Arkema), triethylene glycol diacrylate (e.g., SR272, manufactured by Arkema), polyethylene glycol diacrylate (e.g., A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.), polypropylene glycol diacrylate (e.g., APG-400, manufactured by Shin-Nakamura Chemical Co., Ltd.), tripropylene glycol diacrylate (e.g., SR306H, manufactured by Arkema), 1,3-butanediol dimethacrylate (e.g., BG, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,4-butanediol dimethacrylate (e.g., BD, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,6-hexanediol dimethacrylate (e.g., HD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,9-nonanediol dimethacrylate (e.g., NOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.; Light Acrylate 1,9-ND-M, manufactured by Kyoeisha Chemical Co., Ltd.), 1,10-decanediol dimethacrylate (e.g., DOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,12-dodecanediol dimethacrylate (e.g., SR262, manufactured by Arkema), neopentyl glycol dimethacrylate (e.g., NPG, manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0056] From the viewpoint of improving the balance between improving plasma resistance, improving coating stability in the inkjet method, and improving the effect of low dielectric constant, component (B) is one or more (meth)acrylates selected from the group consisting of 1,12-dodecanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate.

[0057] From the viewpoint of improving inkjet coating properties, the content of component (B) in the sealant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and even more preferably 40 parts by mass or more, based on 100 parts by mass of the polymerizable compound.

[0058] From the viewpoint of improving plasma resistance, the content of component (B) in the sealant is, for example, 75 parts by mass or less, preferably 60 parts by mass or less, more preferably 58 parts by mass or less, and even more preferably 56 parts by mass or less, relative to 100 parts by mass of the polymerizable compound.

[0059] In addition, from the viewpoint of improving inkjet coating properties, the content of component (A) is 60 parts by mass or less, preferably 58 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 50 parts by mass or less, relative to 100 parts by mass of the total of components (A) and (B).

[0060] From the viewpoint of improving plasma resistance, the lower limit of the content of component (A) relative to 100 parts by mass of the total of components (A) and (B) is greater than 0 parts by mass, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more.

[0061] (ingredient (C))

[0062] Component (C) is a monofunctional (meth)acrylate. Specific examples of component (C) include mono(meth)acrylates containing a linear or branched hydrocarbon group in their molecular structure and mono(meth)acrylates containing an aromatic hydrocarbon group in their molecular structure. An example of the former is lauryl methacrylate, and an example of the latter is 3-phenoxybenzyl acrylate.

[0063] From the viewpoint of improving plasma resistance and heat resistance, the display element sealing agent preferably does not contain component (C). That is, the content of component (C) in the display element sealing agent is preferably 0 parts by mass relative to 100 parts by mass of the polymerizable compound.

[0064] From the same viewpoint, when the sealant for display elements contains component (C), the content of component (C) in the sealant for display elements is greater than 0 parts by mass, and is 1 part by mass or less, preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass or less, and even more preferably 0.01 parts by mass or less, relative to 100 parts by mass of the polymerizable compound.

[0065] From the viewpoint of improving the strength of the cured product, the content of the polymerizable compound in the sealant for a display element is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 85% by mass or more, further more preferably 90% by mass or more, and even more preferably 93% by mass or more, relative to the total composition of the sealant.

[0066] Furthermore, from the viewpoint of improving the weather resistance of the sealing material, the content of the polymerizable compound in the sealant is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, further preferably 99% by mass or less, and even more preferably 98% by mass or less, relative to the total composition of the sealant.

[0067] (Curing Agent)

[0068] Specific examples of curing agents include polymerization initiators. From the perspective of stably forming a cured product at low temperatures, the polymerization initiator is preferably a photopolymerization initiator, that is, a compound that generates free radicals or acids upon exposure to ultraviolet light or visible light. Examples of photopolymerization initiators include acylphosphine oxide initiators, oxyphenylacetic acid ester initiators, benzoylformic acid initiators, and hydroxyphenyl ketone initiators.

[0069] Specific examples of the photopolymerization initiator include benzophenone, Michler's ketone, 4,4'-bis(diethylamino)benzophenone, xanthone, thioxanthone, isopropylxanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, camphorquinone, benzanthrone, 4-dimethylamino ethyl benzoate, isopentyl 4-dimethylaminobenzoate, 4,4'-di(tert-butylperoxycarbonyl)benzophenone, 3,4,4'-tri(tert-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetra(tert-hexylperoxycarbonyl)benzophenone, 3,3'-di(methoxycarbonyl)-4,4'-di(tert-butylperoxycarbonyl)benzophenone, 3,4'-di(methoxycarbonyl) )-4,3'-di(tert-butylperoxycarbonyl)benzophenone, 4,4'-di(methoxycarbonyl)-3,3'-di(tert-butylperoxycarbonyl)benzophenone, 2-(4'-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(3',4'-dimethoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, -methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-pentyloxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 4-[p-N,N-bis(ethoxycarbonylmethyl)]-2,6-bis(trichloromethyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(2'-chlorophenyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(4'-methoxyphenyl)-s-triazine, 2-(p-dimethylaminophenyl)benzoyl)- azole, 2-(p-dimethylaminophenyl)benzothiazole, 2-mercaptobenzothiazole, 3,3'-carbonylbis(7-diethylaminocoumarin), 2-(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetrakis(4-ethoxycarbonylphenyl)-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dibromophenyl)-4,4',5,5' -tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 3-(2-methyl-2-dimethylaminopropionyl)carbazole, 3,6-bis(2-methyl-2-morpholinopropionyl)-9-n-dodecylcarbazole, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-[4-(2- 1-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl-1-propanone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-1-propanone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone, 2-hydroxy-phenyl-acetic acid 2-[2-oxo- -2-phenyl-acetoxy-ethoxy]-ethyl ester, hydroxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, methyl benzoylformate, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime)], 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethanone-1-(O-acetyloxime), and the like.

[0070] Among them, from the viewpoint of improving curability, the photopolymerization initiator is preferably one or more compounds selected from the group consisting of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propanone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2- Methyl-1-propanone, 2,2-dimethoxy-2-phenylacetophenone, hydroxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, hydroxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, methyl benzoylformate, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0071] Preferred commercially available photopolymerization initiators include Irgacure 184, Irgacure 651, Irgacure 127, Irgacure 1173, Irgacure 500, Irgacure 2959, Irgacure 754, Irgacure MBF, and Irgacure TPO (all manufactured by BASF), and Omnirad TPO H (manufactured by IGM Resins).

[0072] From the viewpoint of improving curability, the content of the polymerization initiator in the sealant is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, further preferably 1 mass % or more, and even more preferably 2 mass % or more, based on the total composition of the sealant.

[0073] Furthermore, from the viewpoint of suppressing coloration of the sealant, the content of the polymerization initiator in the sealant is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 7% by mass or less, even more preferably 6% by mass or less, and even more preferably 5% by mass or less, relative to the total composition of the sealant.

[0074] (Other ingredients)

[0075] In this embodiment, the sealant may be composed of a polymerizable compound and a curing agent, or may contain other components. Specific examples of other components include one or more additives selected from the group consisting of a tackifier, a filler, a curing accelerator, a plasticizer, a surfactant, a heat stabilizer, a flame retardant, an antistatic agent, a defoaming agent, a leveling agent, and a UV absorber.

[0076] Next, the characteristics of the sealant will be described.

[0077] From the viewpoint of improving the heat resistance of the sealing material, the glass transition temperature (Tg) of the cured product of the sealing agent is 50° C. or higher, preferably 60° C. or higher, and more preferably 70° C. or higher.

[0078] Furthermore, from the viewpoint of improving flexibility, the Tg of the cured product of the sealant is lower than 200°C, preferably 190°C or lower, and more preferably 180°C or lower.

[0079] Here, the Tg of the sealant is specifically measured by the following method. First, the cured sealant is formed by sandwiching the uncured sealant between PET films using a 100 μm thick Teflon (registered trademark) sheet as a mold frame, and then the cured sealant is formed by irradiating the film with a UV-LED of 395 nm at an illumination of 1000 mW / cm 2 , cumulative light intensity 1500mJ / cm 2 It is obtained by solidifying it under the conditions of .

[0080] The obtained cured product was cut with a cutter into a size of 10 mm in width x 40 mm in length to obtain a measurement sample.

[0081] The Tg of the cured product was then measured using a dynamic viscoelasticity measuring apparatus "DMS6100" while applying a frequency of 1 Hz to a measurement sample of the cured product in the atmosphere and heating it from room temperature to 250°C at a rate of 5°C / min. The peak temperature of tan δ was defined as Tg.

[0082] The properties of the sealant are not limited, but the sealant is preferably in a liquid state from the viewpoint of improving the flexibility and plasma resistance of the sealant and being suitable for forming a cured material by a coating method such as an inkjet method.

[0083] In the embodiment, from the viewpoint of stably forming a sealing material such as a resin film, the sealant is preferably a sealant for coating, and more preferably a sealant for coating by an inkjet method.

[0084] From the viewpoint of improving inkjet ejection properties, the viscosity of the sealant measured at 25° C. and 20 rpm using an E-type viscometer is preferably 5 mPa·s or higher, more preferably 8 mPa·s or higher, and even more preferably 10 mPa·s or higher.

[0085] From the viewpoint of improving inkjet ejection properties, the viscosity of the sealant is preferably 30 mPa·s or less, more preferably less than 30.0 mPa·s, further preferably 28.5 mPa·s or less, and even more preferably 27 mPa·s or less.

[0086] From the viewpoint of improving the sealing properties of the sealant, the dielectric constant of the cured sealant is preferably less than 3.5, more preferably 3.4 or less, even more preferably 3.3 or less, even more preferably 3.2 or less, and even more preferably 3.1 or less.

[0087] Furthermore, the dielectric constant of the cured product of the sealant can be set to, for example, 1.0 or more.

[0088] Here, the dielectric constant of the cured sealant is: 2 , cumulative light intensity 1500mJ / cm 2 The dielectric constant of the cured product obtained by curing the curable composition under conditions of 100 kHz was measured at a frequency of 100 kHz.

[0089] Next, a method for producing the sealant will be described.

[0090] The method for producing the sealant is not limited, but includes, for example, mixing a polymerizable compound, a curing agent, and other suitable components, such as various additives, as needed. Examples of methods for mixing the components include using various known kneading machines, such as planetary mixers, homodispersors, universal mixers, Banbury mixers, kneaders, two-roll mills, three-roll mills, and extruders, either alone or in combination, to uniformly mix the components at room temperature or under heating, and under normal pressure, reduced pressure, pressurized conditions, or an inert gas stream.

[0091] The obtained sealant can also be used to form a sealing material. For example, the sealant can be applied to a substrate and dried. Application can be performed using known methods such as inkjet, screen printing, and dispenser coating. Drying can be performed, for example, by heating to a temperature at which the polymerizable compound does not polymerize. The shape of the obtained sealing material is not limited and can be formed into, for example, a film or layer.

[0092] The sealing material is, for example, a cured product obtained by curing the sealant in the present embodiment, and more specifically, a photocured product of the sealant.

[0093] Examples of methods for photocuring the sealant include methods of curing by irradiating the sealant with light using a light source such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, an excimer laser, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, a sodium lamp, a halogen lamp, a xenon lamp, an LED lamp, a fluorescent lamp, sunlight, or an electron beam irradiation device.

[0094] In this embodiment, the polymerizable compound comprises component (A) and component (B) in a specific ratio, and the content of component (C) when included is within a specific range. Therefore, by using a sealant comprising such a polymerizable compound and a curing agent, a sealing material having excellent plasma resistance, stable coating by inkjet method, and both viscosity and low dielectric constant can be obtained. By using a resin layer obtained from such a polymerizable compound as a sealing material, for example, a display device with excellent reliability can be obtained.

[0095] Furthermore, the sealant obtained in this embodiment is suitable for use, for example, in sealing display elements, preferably organic EL display elements. This embodiment provides a sealant that exhibits excellent plasma resistance, allows for stable inkjet coating of the resin layer, and effectively reduces the dielectric constant. This can effectively prevent damage to the display element during the display device manufacturing process, improving the manufacturing stability of the display device.

[0096] Hereinafter, an organic EL display device will be described as an example of a configuration of a display device.

[0097] (Organic EL display device)

[0098] In this embodiment, the organic EL display device includes a layer composed of a cured sealant. By protecting the organic EL element with a resin layer obtained by curing the sealant of this embodiment, it is possible to fully prevent moisture from entering the organic EL element and maintain high performance and durability of the organic EL element.

[0099] The organic EL display device may have a top emission structure or a bottom emission structure.

[0100] The organic EL element is preferably disposed on a substrate and covered in advance with an inorganic material film so as to cover a region including the organic EL element before being protected by a resin layer obtained by curing the sealant in this embodiment.

[0101] Figure 1 It is a cross-sectional view showing a configuration example of the organic EL display device in this embodiment. Figure 1 The display device 100 shown is an organic EL display device and includes a substrate (base material layer 50), a display element (light-emitting element 10) disposed on the base material layer 50, and a sealing layer 22 (which may be an overcoat layer 22 or a barrier layer 22) covering the light-emitting element 10. Furthermore, the sealing layer 22 is composed of, for example, a cured product of the sealant of this embodiment. Specifically, the light-emitting element 10 is an organic EL display element.

[0102] in addition, Figure 1In the embodiment, the display device 100 includes a barrier layer 21 (which may be a touch panel layer 21 or a surface protective layer 21), a sealing layer 22 (which may be an overcoat layer 22 or a barrier layer 22), a planarization layer 23 (which may be a sealing layer 23), and a barrier layer 24 as layers located closer to the viewing side than the light-emitting element 10. The planarization layer 23 is provided on the substrate layer 50 so as to cover the light-emitting element 10, and the barrier layer 24 is provided on the surface of the planarization layer 23. The sealing layer 22 is provided on the substrate layer 50 so as to cover the planarization layer 23 and the barrier layer 24. Furthermore, the barrier layer 21 is provided on the sealing layer 22.

[0103] The material of the base layer 50 is not limited, and various substrates such as glass substrates, silicon substrates, and plastic substrates can be used. A TFT substrate having a plurality of TFTs (thin film transistors) and a planarization layer on the substrate can also be used.

[0104] Examples of the inorganic material constituting the barrier layer 24, ie, the inorganic material film, include silicon nitride (SiN x ), silicon oxide (SiO x ), aluminum oxide (Al2O3), etc. The inorganic material film may be a single layer or a laminate of multiple layers.

[0105] As a method for covering the light emitting element 10 with an inorganic material film, for example, when the inorganic material film is made of silicon nitride or silicon oxide, sputtering, electron cyclotron resonance (ECR) plasma CVD, and the like can be cited.

[0106] The sputtering method can be performed using, for example, argon, nitrogen, or the like as a carrier gas, a single gas or a mixed gas, at room temperature, a power of 50 to 1000 W, and a pressure of 0.001 to 0.1 Torr.

[0107] In addition, in the ECR plasma CVD method, for example, a mixed gas of SiH4 and O2 or a mixed gas of SiH4 and N2 can be used, and it can be carried out under the conditions of temperature 30℃~100℃, pressure 10mTorr~1Torr, frequency 2.45GHz, and power 10~1000W.

[0108] The thickness of the inorganic material film formed on the light emitting element 10 is not limited, but is, for example, 0.01 to 10 μm, preferably 0.1 to 5 μm, from the viewpoint of improving sealing performance and flexibility.

[0109] As a method for protecting the light emitting element 10 with a resin layer obtained by curing the sealant of this embodiment, for example, the sealant is applied to the light emitting element 10 and then cured. An inkjet method is preferably used as the coating method.

[0110] The thickness of the resin layer is not limited, but is, for example, 0.1 to 50 μm, preferably 1 to 20 μm, from the viewpoint of improving sealing performance and flexibility.

[0111] In addition, in the display device 100, an inorganic material film (barrier layer 24) is preferably further laminated on the resin layer to enhance the effect of protecting the light-emitting element 10 from moisture and oxygen in the atmosphere. The inorganic material constituting the inorganic material film laminated on the resin layer and the method for forming the inorganic material film are the same as those for the inorganic material film covering the light-emitting element 10.

[0112] The thickness of the inorganic material film formed on the resin layer is not limited, but is, for example, 0.01 to 10 μm, preferably 0.1 to 5 μm, from the viewpoint of improving sealing performance and flexibility.

[0113] In the display device 100, a barrier layer 24 and a sealing layer 22 are provided on the light emitting element 10. The sealing layer 22 is composed of a resin layer obtained by curing the sealant in this embodiment. Therefore, a display device 100 with excellent reliability can be obtained. Specifically, when the barrier layer 24 is formed on the upper part of the sealing layer 22 and a plasma treatment process is performed, damage to the barrier layer 24 can be suppressed. In addition, it is also possible to suppress the damage to the barrier layer 24. For example, in the case of SiN x Pinholes were generated in the barrier layer 24 of the film.

[0114] Example

[0115] Hereinafter, the present invention will be described using Examples and Comparative Examples, but the present invention is not limited thereto.

[0116] First, materials used in the following examples are shown.

[0117] (Polymerizable compound)

[0118] (A) Alicyclic

[0119] UV curing resin 1: Dimethyloltricyclodecane diacrylate, Light Acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.

[0120] UV curing resin 2: Dimethyloltricyclodecane dimethacrylate, Light Acrylate DCP-M, manufactured by Kyoeisha Chemical Co., Ltd.

[0121] (B) Chain

[0122] UV curing resin 3: 1,12-dodecanediol dimethacrylate, SR262, manufactured by Arkema

[0123] UV curing resin 4: 1,9-nonanediol diacrylate, Light Acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd.

[0124] UV curing resin 5: 1,9-nonanediol dimethacrylate, Light Acrylate 1,9ND-M, manufactured by Kyoeisha Chemical Co., Ltd.

[0125] UV curing resin 6: triethylene glycol diacrylate, SR272, manufactured by Arkema

[0126] UV curing resin 7: tripropylene glycol diacrylate, SR306H, manufactured by Arkema

[0127] (C)-1: linear monofunctional

[0128] UV curing resin 8: Lauryl methacrylate, Light Acrylate L, manufactured by Kyoeisha Chemical Co., Ltd.

[0129] (C)-2: Aromatic monofunctional

[0130] UV curing resin 9: 3-phenoxybenzyl acrylate, Light Acrylate POB-A, manufactured by Kyoeisha Chemical Co., Ltd.

[0131] (Polymerization initiator)

[0132] UV free radical initiator 1: 2,4,6-trimethylbenzoyldiphenylphosphine oxide, Omnirad TPO H, manufactured by IGM Resins

[0133] (Examples 1 to 5, Comparative Examples 1 to 4)

[0134] The components were blended to form the composition shown in Table 1 to obtain a liquid curable composition as a sealant.

[0135] The physical properties of the sealant or its cured product obtained in each example were measured by the following methods. The measurement results are shown in Table 1.

[0136] (Viscosity)

[0137] The viscosity of the curable composition obtained in each example was measured using an E-type viscometer (LV DV-II+Pro, manufactured by Brookfield) at 25° C. and 20 rpm. A viscosity value of less than 30 mPa·s was considered acceptable.

[0138] (Glass transition temperature)

[0139] First, a cured sealant was obtained by the following procedure: a 100 μm thick Teflon (registered trademark) sheet was used as a mold frame, uncured sealant was sandwiched between PET films, and a UV-LED with a wavelength of 395 nm was used at an illumination of 1000 mW / cm 2 , cumulative light intensity 1500mJ / cm 2 and solidifying it under the conditions of 5% to obtain a solidified material.

[0140] The obtained cured product was cut with a cutter into a size of 10 mm in width x 40 mm in length to obtain a measurement sample.

[0141] Then, tan δ was measured using a dynamic viscoelasticity measuring apparatus "DMS6100" while applying a frequency of 1 Hz to the measurement sample of the cured product in the atmosphere and heating it from room temperature to 250° C. at 5° C. / min. The obtained tan δ peak temperature was defined as Tg.

[0142] (Dielectric constant)

[0143] A coating film for obtaining a cured product for dielectric constant measurement was prepared using the following method. Specifically, the obtained sealant was introduced into an inkjet cartridge DMC-11610 (manufactured by Fujifilm Dimatix). This inkjet cartridge was then mounted on an inkjet device DMP-2831 (manufactured by Fujifilm Dimatix). After adjusting the discharge state, the sealant was applied to a substrate prepared by vapor-depositing aluminum on alkali-free glass to a thickness of 100 nm. The film was then coated to a thickness of 10 μm after curing, forming a 5 cm × 5 cm film.

[0144] The obtained coating film was placed in a box under the conditions of room temperature (25°C) and nitrogen flow for 5 minutes, and then the film was placed in a box under the conditions of illumination of 1000 mW / cm 2 , cumulative light intensity 1500mJ / cm 2 Under the conditions of irradiation, ultraviolet rays with a wavelength of 395nm are formed to form a cured film.

[0145] Aluminum was then deposited on the inkjet coated surface to a thickness of 100 nm, and the dielectric constant was measured at 100 kHz using an LCR meter HP4284A (manufactured by Agilent Technologies) using an automatic balanced bridge method. A dielectric constant value of less than 3.5 was considered acceptable.

[0146] (Organic EL device damage)

[0147] As an indicator of the plasma resistance of the sealant, damage to the organic EL element during the plasma treatment step was evaluated by the following method.

[0148] The sealant obtained in each example was introduced into an inkjet cartridge DMC-11610 (manufactured by Fujifilm Dimatix). This inkjet cartridge was then mounted on an inkjet device DMP-2831 (manufactured by Fujifilm Dimatix). After adjusting the discharge state, the sealant was applied to a glass substrate in a 15 mm x 15 mm size to a thickness of 10 μm after curing.

[0149] The obtained coating film was placed in a box under the conditions of room temperature (25°C) for 5 minutes while nitrogen was circulated, and then heated at 1500 mW / cm 2 Irradiate with ultraviolet light of 395 nm wavelength for 1 second to form a cured film.

[0150] The sample having the cured film formed thereon was subjected to plasma treatment for 1 minute under the conditions of a 2500 W ICP power supply, a 300 W RF power supply, a DC bias of 200 V, an argon (Ar) flow rate of 50 sccm, and a pressure of 10 mtorr.

[0151] Then, SiN x The target was sputtered by RF sputtering to form an inorganic sealing layer (SiN x membrane).

[0152] On the other hand, an OLED element was vapor-deposited on a counter substrate, and the substrate on which the inorganic sealing layer was formed was bonded together to obtain a sample for evaluation.

[0153] Reliability testing of the samples obtained in each example was conducted at 85°C. Specifically, the luminous area ratio (%) of each sample obtained in each example after storage at 85°C for 100 hours was determined using the following method. Motic Images Plus software (manufactured by Shimadzu Corporation) was used to calculate the luminous area ratio in the initial state and after 100 hours of storage. A luminous area ratio of 50% or greater was considered acceptable.

[0154] [Table 1]

[0155]

[0156] Table 1 shows that the sealants obtained in each example are excellent in suppressing damage to the organic EL element due to plasma irradiation. In addition, the sealants obtained in each example have an excellent balance among viscosity, dielectric constant, and Tg.

[0157] This application claims the benefit of priority based on Japanese patent application No. 2020-157660, filed on September 18, 2020, and incorporates herein all of its disclosure.

[0158] Explanation of symbols

[0159] 10 light-emitting elements

[0160] 21 Barrier layer, touch panel layer or surface protection layer

[0161] 22 Sealant layer, outer layer or barrier layer

[0162] 23. Planarization layer or sealing layer

[0163] 24 Barrier layer

[0164] 50 base material layer

[0165] 100 display device.

Claims

1. A sealant for a display element, comprising a polymerizable compound and a curing agent, The polymerizable compound comprises the following components (A) and (B): (A) a difunctional or higher-functional (meth)acrylate having an alicyclic structure, (B) a bifunctional (meth)acrylate having a chain structure, The content of the component (A) is 60 parts by mass or less relative to 100 parts by mass of the total of the component (A) and the component (B). The content of the component (C) in the sealant for display elements is 0 parts by mass relative to 100 parts by mass of the polymerizable compound, and the component (C) is a monofunctional (meth)acrylate. The content of the polymerizable compound in the sealant for display elements is 80% by mass or more based on the entire composition of the sealant for display elements. 2 . The sealing agent for a display element according to claim 1 , wherein the component (A) contains dimethyloltricyclodecane di(meth)acrylate.

3. The sealant for a display element according to claim 1 or 2, wherein the component (B) is one or more (meth)acrylates selected from the group consisting of 1,12-dodecanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate. The display element sealing agent according to claim 1 or 2, which is used for sealing an organic EL display element. 5 . A cured product obtained by curing the sealant for a display element according to claim 1 .

6. A display device comprising: a substrate, a display element disposed on the substrate, and a sealing layer covering the display element. The sealing layer is composed of a cured product of the sealant for a display element according to any one of claims 1 to 4.

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