Encapsulant for display

Abstract

The present invention relates to an encapsulant for a display. The present invention relates to an encapsulant for a display that can also be applied to a flexible display or a curved display. More specifically, the present invention relates to an encapsulant for a display that uses a urethane (meth) acrylate formed from a polyol component having an aromatic ring, and provides an encapsulant for a display that has both flexibility and low moisture permeability and excellent adhesiveness. An encapsulant for a display, comprising (A) a urethane (meth) acrylate obtained by reacting (a) a polyol having an aromatic ring, (b) an organic polyisocyanate, and (c) a hydroxyl-containing (meth) acrylate.

Description

Technical Field

[0001] The present invention relates to a display encapsulant that can be applied to flexible displays and curved displays. The display encapsulant has both flexibility and low moisture permeability, and is therefore particularly useful as an encapsulant for flexible displays and curved displays.

[0002] In addition, the encapsulant having high flexibility like the encapsulant of the present invention has excellent adhesion to an adherend and is therefore useful in applications requiring high adhesive strength. Background Art

[0003] Examples of encapsulants for displays include sealants for liquid crystal displays, encapsulants for organic electroluminescent (EL) displays, adhesives for touch panels, etc. These materials have the following characteristics in common: excellent curability, little outgassing, and no damage to display elements.

[0004] In addition, recently, curved displays and flexible displays have been developed and commercialized. For substrates used in such displays, soft substrates such as plastic films are used instead of conventional rigid substrates such as glass (Patent Document 1).

[0005] Under such circumstances, the encapsulant for a display is required to have a property of following the bending of a substrate or the like, that is, a property of being flexible even after curing.

[0006] In addition, an encapsulant with excellent flexibility is also advantageous in terms of adhesive strength. For example, it can reduce peeling and device breakage caused by impact. From this point of view, the demand for encapsulants to impart flexibility becomes higher.

[0007] On the other hand, in order to improve the flexibility of the cured product, reducing the crosslinking density of the cured product is an effective means. However, usually when the crosslinking density is reduced, the moisture permeability is deteriorated. It is believed that this is because moisture enters from the sparse part of the crosslinked network of the cured product. Therefore, in order to ensure low moisture permeability, it is necessary to achieve the following opposite characteristics: improve flexibility when the crosslinking density is not reduced, or do not deteriorate the moisture permeability although the crosslinking density is reduced.

[0008] Conventionally, adhesives for display elements having flexibility have been developed from the viewpoint of improving adhesive strength (Patent Document 2). However, adhesives for display elements having performance sufficient to cope with the above-mentioned flexible substrates have not yet been realized.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2012-238005

[0012] Patent Document 2: Japanese Patent Application Publication No. 2016-24240 Summary of the invention

[0013] Problems to be solved by the invention

[0014] The present invention relates to a display encapsulant that can also be applied to flexible displays and curved displays. More specifically, the present invention relates to a display encapsulant using a urethane (meth)acrylate formed from a polyol component having an aromatic ring, and an object of the present invention is to provide a display encapsulant that has both flexibility and low moisture permeability and excellent adhesiveness.

[0015] Means used to solve problems

[0016] As a result of intensive studies, the present inventors have found that a display encapsulant containing urethane (meth)acrylate formed from a polyol component having an aromatic ring has extremely excellent flexibility and low moisture permeability, thereby completing the present invention.

[0017] In addition, in this specification, "(meth)acrylate" means "acrylate" and / or "methacrylate".

[0018] That is, the present invention relates to the following [1] to

[12] . [1]

[0020] A display encapsulant, wherein the display encapsulant contains (A) urethane (meth)acrylate obtained by reacting (a) a polyol having an aromatic ring, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate. [2]

[0022] The encapsulant for a display according to the aforementioned item [1], wherein the component (a) is a polyester polyol having an aromatic ring. [3]

[0024] The encapsulant for a display according to the above item [2], wherein the polyester polyol having an aromatic ring is formed from (a-1) a polyol and (a-2) a dibasic acid having an aromatic ring or an anhydride thereof. [4]

[0026] The encapsulant for a display according to any one of the aforementioned items [1] to [3], further comprising a curable compound as a component (B). [5]

[0028] The encapsulant for a display according to the above item [4], wherein the component (B) is a partial epoxy (meth)acrylate. [6]

[0030] The encapsulating agent for a display according to any one of the above items [1] to [5], further comprising a component (C) an organic filler. [7]

[0032] The encapsulant for a display according to the above item [6], wherein the component (C) is one or two or more organic fillers selected from the group consisting of polyurethane fine particles, acrylic polymer fine particles, styrene polymer fine particles, styrene-olefin copolymer fine particles and polysiloxane fine particles. [8]

[0034] The encapsulating agent for a display according to any one of the aforementioned items [1] to [7], further comprising a component (D) a thermosetting agent. [9]

[0036] The encapsulant for a display according to any one of the above items [1] to [8], further comprising a component (E) a photoradical polymerization initiator.

[10]

[0038] The encapsulant for a display according to any one of the above items [1] to [9], further comprising a component (F) a thermal radical polymerization initiator.

[11]

[0040] The encapsulant for a display according to the above item

[10] , wherein the component (F) is a thermal radical polymerization initiator containing no oxygen-oxygen bond (—OO—) and no nitrogen-nitrogen bond (—N═N—) in the molecule.

[12]

[0042] The sealing agent for a display according to any one of the aforementioned items [1] to

[11] , wherein the sealing agent for a display is a liquid crystal sealing agent for a liquid crystal dropping method.

[13]

[0044] A liquid crystal display, wherein the liquid crystal display is sealed with a liquid crystal sealant using the liquid crystal dropping method described in the above item

[12] .

[0045] Effects of the Invention

[0046] The encapsulant for displays of the present invention can provide an encapsulant for displays which has both flexibility and low moisture permeability and is also excellent in adhesiveness. DETAILED DESCRIPTION

[0047] The encapsulant for a display of the present invention contains (A) urethane (meth)acrylate (hereinafter also referred to as "component (A)"), wherein the urethane (meth)acrylate is composed of (a) a polyol having an aromatic ring, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate.

[0048] Component (A) has a soft skeleton peculiar to a urethane structure, and the polyol component has an aromatic ring. Therefore, the cured product has softness and low moisture permeability and has high adhesive strength not only to a glass substrate but also to an alignment film.

[0049] Regarding flexibility, the elastic modulus of the cured product can be used as an indicator. 2 The elastic modulus of the cured product with a thickness of 100 μm obtained by curing at 130° C. for 40 minutes after exposure to ultraviolet light (measurement wavelength: 365 nm) is preferably 100 MPa to 3000 MPa at room temperature (25° C.), more preferably 300 MPa to 1900 MPa, and particularly preferably 400 MPa to 1500 MPa. The display adhesive in the above range can follow the stress applied to the display, so it can be said to be preferred.

[0050] As for moisture permeability, the moisture permeability of the cured product with a thickness of 300 μm is preferably 60 g / m 2 × 24h or less, more preferably 55g / m 2 × 24h or less, particularly preferably 50g / m 2 ×24h or less.

[0051] Component (A) can be obtained by synthesis using (a) a polyol having an aromatic ring, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate according to a conventional method.

[0052] It is preferred that 1.1 to 2.0 equivalents, and particularly preferably 1.3 to 2.0 equivalents, of the isocyanate groups of the component (b) are reacted per 1 equivalent of the hydroxyl groups of the component (a). The reaction temperature is preferably room temperature (25°C) to 100°C.

[0053] Preferably, 0.95 to 1.1 equivalents of hydroxyl groups in component (c) are reacted per 1 equivalent of isocyanate groups in the reaction product of component (a) and component (b). The reaction temperature is preferably room temperature (25°C) to 100°C.

[0054] Component (a) is a polyol component having an aromatic ring, and examples of the aromatic ring include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthroline ring; and aromatic heterocyclic rings such as a furan ring, a pyrrole ring, a thiophene ring, a pyridine ring, a thiazole ring, and a benzothiazole ring, preferably a benzene ring or a naphthalene ring. In addition, component (a) is preferably a polyester polyol, and more preferably a polyester polyol formed from (a-1) a polyol and (a-2) a dibasic acid having an aromatic ring or an anhydride thereof.

[0055] In addition, the urethane (meth)acrylate of the present invention may be used in combination with a polyol other than the component (a).

[0056] Specific examples of the polyol that can be used as component (a-1) include hydrogenated polybutadiene polyol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, cyclohexane-1,4-dimethanol, polyethylene glycol, polypropylene glycol, bisphenol A poly (n≈2 to 20) ethoxylated glycol, bisphenol A poly (n≈2 to 20) propoxylated glycol, and the like.

[0057] Examples of the dibasic acid or its anhydride having an aromatic ring that can be used as component (a-2) include isophthalic acid, terephthalic acid, phthalic acid, or their anhydrides. The urethane (meth)acrylate of the present invention may be used in combination with a dibasic acid or its anhydride other than component (a-2).

[0058] Specific examples of (b) organic polyisocyanates include toluene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-cyclohexylmethane diisocyanate, xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate, etc. Toluene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate are preferred, and toluene diisocyanate having an aromatic ring is particularly preferred.

[0059] Specific examples of (c) hydroxyl-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,4-butanediol (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, ε-caprolactone adduct of 2-hydroxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, etc. Preferred examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0060] The preferred content of component (A) in the total amount of the encapsulant for a display is usually 5 to 50% by mass, preferably 10 to 40% by mass, and more preferably 20 to 30% by mass.

[0061] The preferred content of component (A) in the total amount of component (A) and component (B) described below is usually 10 to 60% by mass, preferably 20 to 50% by mass, and more preferably 25 to 40% by mass.

[0062] [(B) Curable Compound]

[0063] The encapsulating agent for a display of the present invention contains a curable compound as a component (B) (hereinafter also simply referred to as “component (B)”).

[0064] The component (B) is not particularly limited as long as it is a compound that is cured by light, heat, or the like, but is preferably a (meth)acrylate, and examples thereof include (meth)acrylate, epoxy (meth)acrylate, and epoxy resin.

[0065] [(Meth)acrylate]

[0066] Specific examples of (meth)acrylates include N-acryloyloxyethyl hexahydrophthalimide, acryloyl morpholine, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexane-1,4-dimethanol mono(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenoxyethyl (meth)acrylate, phenylpolyethoxy (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, o-phenylphenol monoethoxy (meth)acrylate, o-phenylphenol polyethoxy (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, tribromophenoxyethyl (meth)acrylate, tetrahydrodicyclopentadienyl (meth)acrylate, dihydrodicyclopentadienyl (meth)acrylate, dihydrodicyclopentadienyloxyethyl (meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol Di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A polypropoxy di(meth)acrylate, bisphenol F polyethoxy di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, isocyanuric acid tri(acryloyloxyethyl) ester, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate Monomers such as dimethoate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate, trimethylolpropane tetra(meth)acrylate, diacrylate of an ester of neopentyl glycol and hydroxypivalic acid, or diacrylate of an ε-caprolactone adduct of an ester of neopentyl glycol and hydroxypivalic acid. Preferred monomers include N-acryloyloxyethyl hexahydrophthalimide, phenoxyethyl (meth)acrylate, dihydrodicyclopentadienyloxyethyl (meth)acrylate, o-phenylphenol monoethoxy (meth)acrylate, and o-phenylphenol polyethoxy (meth)acrylate.

[0067] Epoxy (meth)acrylate is obtained by a known method through a reaction between an epoxy resin and (meth)acrylic acid. The epoxy resin used as a raw material is not particularly limited, but preferably is a difunctional or higher epoxy resin, for example, resorcinol diglycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, phenol novolac type epoxy resin having a trishydroxyphenylmethane skeleton, and diglycidyl ethers of difunctional phenols such as catechol and resorcinol, diglycidyl ethers of difunctional alcohols, and their halogenated products, hydrogenated products, etc. Among them, bisphenol A epoxy resin and resorcinol diglycidyl ether are preferred from the viewpoint of liquid crystal contamination. In addition, the ratio of epoxy group to (meth)acryloyl group is not limited and can be appropriately selected from the viewpoint of process adaptability.

[0068] It is preferable to use a partial epoxy (meth)acrylate in which a part of the epoxy group is acrylated. In this case, the acrylate ratio is preferably 30% to 70%, and more preferably 40% to 60%.

[0069] The (meth)acrylate may be used alone or in combination of two or more. In the encapsulant for display of the present invention, when the (meth)acrylate is used, the amount thereof is preferably 20% to 70% by mass, more preferably 30% to 60% by mass, based on the total amount of the encapsulant for display.

[0070] [Epoxy resin]

[0071] As an aspect of the present invention, it is preferred that the component (B) further contains an epoxy resin.

[0072] The epoxy resin is not particularly limited, but preferably is a difunctional or higher epoxy resin, for example, resorcinol diglycidyl ether, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, bisphenol F novolac epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, hydantoin epoxy resin, isocyanurate epoxy resin, phenol novolac epoxy resin having a trishydroxyphenylmethane skeleton, and diglycidyl ethers of difunctional phenols such as catechol and resorcinol, diglycidyl ethers of difunctional alcohols, and their halogenated products, hydrogenated products, etc. Among them, bisphenol A type epoxy resin and resorcinol diglycidyl ether are preferred from the viewpoint of liquid crystal contamination.

[0073] The epoxy resin may be used alone or in combination of two or more. In the encapsulant for display of the present invention, when the epoxy resin is used, the epoxy resin is preferably used in an amount of 5 to 30% by mass, more preferably 5 to 20% by mass, based on the total amount of the encapsulant for display.

[0074] [(C) Organic filler]

[0075] The encapsulant for display of the present invention may contain an organic filler as component (C) (hereinafter also referred to as "component (C)"). Examples of the organic filler include polyurethane particles, acrylic polymer particles, styrene polymer particles, styrene-olefin copolymer particles, and polysiloxane particles. It should be noted that polysiloxane particles are preferably KMP-594, KMP-597, KMP-598 (manufactured by Shin-Etsu Chemical Co., Ltd.), Torayfil RTM E-5500, 9701, EP-2001 (manufactured by Dow Corning Toray Co., Ltd.), as polyurethane microparticles, JB-800T, HB-800BK (manufactured by Negami Industries Co., Ltd.) are preferred, as styrene polymer microparticles, Rabalon RTM T320C, T331C, SJ4400, SJ5400, SJ6400, SJ4300C, SJ5300C, SJ6300C (Mitsubishi Chemical), as styrene-olefin copolymer fine particles, SEPTONRT is preferred M SEPS2004, SEPS2063.

[0076] These organic fillers can be used alone or in combination of two or more. In addition, two or more can be used to form a core-shell structure. Among them, acrylic polymer microparticles and polysiloxane microparticles are preferred.

[0077] When the acrylic polymer particles are used, preferably, the acrylic rubber has a core-shell structure comprising two acrylic rubbers, and particularly preferably, the acrylic rubber has a core layer of n-butyl acrylate and a shell layer of methyl methacrylate. RTM The F-351 version is sold by AICA KOGYO CO., LTD.

[0078] In addition, as the above-mentioned polysiloxane particles, there can be listed: organic polysiloxane crosslinked powder, straight-chain dimethyl polysiloxane crosslinked powder, etc. In addition, as the composite silicone rubber, there can be listed a composite silicone rubber obtained by coating the surface of the above-mentioned silicone rubber with a polysiloxane resin (for example, a polyorganosilsesquioxane resin). Among these particles, silicone rubber of straight-chain dimethyl polysiloxane crosslinked powder, or composite silicone rubber particles of straight-chain dimethyl polysiloxane crosslinked powder coated with a polysiloxane resin are particularly preferred. These particles can be used alone or in combination of two or more. In addition, preferably, with regard to the shape of the rubber powder, a spherical shape with little increase in viscosity after addition is good. In the encapsulant for display of the present invention, when component (C) is used, it is preferably 1% by mass to 30% by mass, and more preferably 2% by mass to 10% by mass in the total amount of the encapsulant for display.

[0079] [(D) Heat curing agent]

[0080] The encapsulant for a display of the present invention may contain a thermosetting agent as a component (D) (hereinafter also simply referred to as “component (D)”) to improve reactivity.

[0081] As component (D), for example, compounds having a carboxyl group bonded to an aromatic ring in the molecule, polyamines, polyphenols, organic acid hydrazides, etc. can be cited. However, it is not limited to these substances. For example, as aromatic hydrazides, terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthalene dicarboxylic acid dihydrazide, 2,6-pyridine dihydrazide, 1,2,4-benzene trimellitic acid hydrazide, 1,4,5,8-naphthalene tetracarboxylic acid tetrahydrazide, pyromellitic acid tetrahydrazide, etc. can be cited. In addition, in the case of aliphatic hydrazides, for example, formic hydrazide, acetic hydrazide, propionic hydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, sebacic acid dihydrazide, 1,4-cyclohexane dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, iminodiacetic acid dihydrazide, N,N'-hexamethylenebisaminourea, citric acid trihydrazide, nitrilotriacetic acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, Dihydrazides having a hydantoin skeleton, preferably a valine hydantoin skeleton (a skeleton in which the carbon atoms of the hydantoin ring are substituted with isopropyl groups), such as 1,3-bis(hydrazinocarbonylethyl)-5-isopropylhydantoin, tris(1-hydrazinocarbonylmethyl)isocyanurate, tris(2-hydrazinocarbonylethyl)isocyanurate, tris(1-hydrazinocarbonylethyl)isocyanurate, tris(3-hydrazinocarbonylpropyl)isocyanurate, bis(2-hydrazinocarbonylethyl)isocyanurate, and the like. From the perspective of the balance between curing reactivity and latency, preferred are isophthalic acid dihydrazide, malonic acid dihydrazide, adipic acid dihydrazide, tris(1-hydrazinocarbonylmethyl)isocyanurate, tris(1-hydrazinocarbonylethyl)isocyanurate, tris(2-hydrazinocarbonylethyl)isocyanurate, and tris(3-hydrazinocarbonylpropyl)isocyanurate, and particularly preferred is tris(2-hydrazinocarbonylethyl)isocyanurate.

[0082] As component (D), a compound having a carboxyl group bonded to an aromatic ring in the molecule is preferably used, and examples thereof include 4-hydroxybenzoic acid, thiosalicylic acid, terephthalic acid, citrazinic acid, 4-aminobenzoic acid, 4-(aminomethyl)benzoic acid, and 2-mercaptonicotinic acid.

[0083] Component (D) may be used alone or in combination of two or more. In the encapsulant for display of the present invention, when component (D) is used, the amount thereof is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total amount of the encapsulant for display.

[0084] The display encapsulant of the present invention can achieve further improvement in reactivity by adding a curing catalyst. Examples of the curing catalyst include amines and imidazoles, with imidazoles being particularly preferred. Examples of the imidazoles include 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 2,4-diamino-6-(2'-methylimidazole (1'))ethyl-s-triazine, 2,4-diamino-6-(2'-undecylimidazole (1 '))ethyl-s-triazine, 2,4-diamino-6-(2'-ethyl-4-methylimidazole (1'))ethyl-s-triazine, 2,4-diamino-6-(2'-methylimidazole (1'))ethyl-s-triazine·isocyanuric acid adduct, 2-methylimidazole isocyanuric acid 2:3 adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-3,5-dihydroxymethylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 1-cyanoethyl-2-phenyl-3,5-bis(cyanoethoxymethyl)imidazole, etc.

[0085] [(E) Photoradical polymerization initiator]

[0086] The encapsulant for display of the present invention may contain a photoradical polymerization initiator as component (E) (hereinafter also referred to as "component (E)"). As the photoradical polymerization initiator, there is no particular limitation as long as it is a compound that generates free radicals or acids by irradiation with ultraviolet light or visible light and initiates a chain polymerization reaction. Examples thereof include: benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, diethyl thioxanthone, benzophenone, 2-ethyl anthraquinone, 2-hydroxy-2-methyl propiophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholinyl-1-propane, 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, camphorquinone, 9-fluorenone, diphenyl disulfide, etc. Specifically, IRGACURE RTM 651, 184, 2959, 127, 907, 369, 379EG, 819, 784, 754, 500, OXE01, OXE02, OXE03, OXE04, DAROCURE RTM 1173, LUCIRIN RTM TPO (both manufactured by BASF), SEIKUOL RTM Z, BZ, BEE, BIP, BBI (all manufactured by Seiko Chemical Co., Ltd.), KAYACURE DETX-S (manufactured by Nippon Kayaku Co., Ltd.), etc. Among them, IRGACURE RTMOXE01, OXE02, OXE03, OXE04 and KAYACURE DETX-S as a thioxanthone initiator.

[0087] Furthermore, the combined use of an oxime ester initiator and a thioxanthone initiator is preferred because both immediate curing property and light-shielding area curing property can be achieved and curing is possible even with visible light.

[0088] In the encapsulating agent for displays of the present invention, when component (E) is used, the amount thereof is usually 0.001 to 3% by mass, preferably 0.01 to 2% by mass, based on the total amount of the encapsulating agent for displays.

[0089] [(F) Thermal radical polymerization initiator]

[0090] The encapsulant for a display of the present invention may contain (F) a thermal radical polymerization initiator (hereinafter also simply referred to as “component (F)”) to improve the curing speed and curability.

[0091] The thermal radical polymerization initiator is not particularly limited as long as it is a compound that generates free radicals by heating and initiates a chain polymerization reaction, and examples thereof include organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol, etc., and benzopinacol is preferably used. For example, as an organic peroxide, Kayamek RTM A, M, R, L, LH, SP-30C; Perkadox CH-50L, BC-FF; Cadox B-40ES: Perkadox 14; Trigonox RTM 22-70E, 23-C70, 121, 121-50E, 121-LS50E, 21-LS50E, 42, 42LS; Kayaester RTM P-70, TMPO-70, CND-C70, OO-50E, AN; Kayabutyl RTM B; Perkadox 16; Kayacarbon RTM BIC-75, AIC-75 (manufactured by AKZO Co., Ltd.); Permeck RTM N, H, S, F, D, G; Perhexa RTM H, HC, TMH, C, V, 22, MC; Percure RTM AH, AL, HB; Perbutyl RTM H, C, ND, L; Percumyl RTM H, D; Peroyl RTM IB, IPP; Perocta RTMND (manufactured by NOF Corporation), etc.

[0092] In addition, as the azo compound, VA-044, 086, V-070, VPE-0201, VSP-1001 (manufactured by Wako Pure Chemical Industries, Ltd.) and the like are available as commercial products.

[0093] As component (F), a thermal free radical polymerization initiator having no oxygen-oxygen bond (-OO-) or nitrogen-nitrogen bond (-N=N-) in the molecule is preferred. A thermal free radical polymerization initiator having an oxygen-oxygen bond (-OO-) or nitrogen-nitrogen bond (-N=N-) in the molecule generates a large amount of oxygen or nitrogen when generating free radicals, so that the liquid crystal sealant is cured in a state where bubbles remain in the liquid crystal sealant, which may cause a decrease in adhesive strength, a decrease in moisture permeability, and a decrease in characteristics under a hot and humid environment. Particularly preferred are benzopinacol-based thermal free radical polymerization initiators (including those obtained by chemically modifying benzopinacol). Specific examples include benzopinacol, 1,2-dimethoxy-1,1,2,2-tetraphenylethane, 1,2-diethoxy-1,1,2,2-tetraphenylethane, 1,2-diphenoxy-1,1,2,2-tetraphenylethane, 1,2-dimethoxy-1,1,2,2-tetra(4-methylphenyl)ethane, 1,2-diphenoxy-1,1,2,2-tetra(4-methoxyphenyl)ethane, )ethane, 1,2-bis(trimethylsilyloxy)-1,1,2,2-tetraphenylethane, 1,2-bis(triethylsilyloxy)-1,1,2,2-tetraphenylethane, 1,2-bis(tert-butyldimethylsilyloxy)-1,1,2,2-tetraphenylethane, 1-hydroxy-2-trimethylsilyloxy-1,1,2,2-tetraphenylethane, 1-hydroxy-1,2-triethylsilyloxy Alkoxy-1,1,2,2-tetraphenylethane, 1-hydroxy-2-tert-butyldimethylsilyloxy-1,1,2,2-tetraphenylethane, etc. are preferred, 1-hydroxy-2-trimethylsilyloxy-1,1,2,2-tetraphenylethane, 1-hydroxy-2-triethylsilyloxy-1,1,2,2-tetraphenylethane, 1-hydroxy-2-tert-butyldimethylsilyloxy-1,1,2,2-tetraphenylethane, 1,2-bis(trimethylsilyloxy)-1,1,2,2-tetraphenylethane are preferred, 1-hydroxy-2-trimethylsilyloxy-1,1,2,2-tetraphenylethane, 1,2-bis(trimethylsilyloxy)-1,1,2,2-tetraphenylethane are more preferred, and 1,2-bis(trimethylsilyloxy)-1,1,2,2-tetraphenylethane is particularly preferred.

[0094] The above-mentioned benzopinacol is commercially available from Tokyo Chemical Industry Co., Ltd., Wako Pure Chemical Industries, Ltd., etc. In addition, the etherification of the hydroxyl group of benzopinacol can be easily synthesized by a known method. In addition, the silyl etherification of the hydroxyl group of benzopinacol can be synthesized by heating the corresponding benzopinacol with various silylating agents in the presence of a basic catalyst such as pyridine. As the silylating agent, trimethylchlorosilane (TMCS), hexamethyldisilazane (HMDS), N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) which are commonly known as trimethylsilylating agents, triethylchlorosilane (TECS) as a triethylsilylating agent, tert-butylmethylsilane (TBMS) as a tert-butyldimethylsilylating agent, etc. can be cited. These reagents can be easily obtained from the market such as silicon derivative manufacturers. As the reaction amount of the silylating agent, it is preferably 1.0 times mole to 5.0 times mole relative to 1 mole of hydroxyl group of the target compound. More preferably, it is 1.5 to 3.0 times the mole. When it is less than 1.0 times the mole, the reaction efficiency is poor and the reaction time is long, thus promoting thermal decomposition. When it is more than 5.0 times the mole, separation is poor during recovery or purification is difficult.

[0095] The content of the component (F) is preferably 0.0001 to 10% by mass, more preferably 0.0005 to 3% by mass, and particularly preferably 0.001 to 1% by mass, based on the total amount of the encapsulant for a display of the present invention.

[0096] [(O) Other ingredients]

[0097] The encapsulant for a display of the present invention may further contain additives such as an inorganic filler, a silane coupling agent, a radical polymerization inhibitor, a pigment, a leveling agent, a defoaming agent, and a solvent as required.

[0098] [Inorganic filler]

[0099] As the above-mentioned inorganic filler, there can be listed: silicon dioxide, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, aluminum oxide, magnesium oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, etc., preferably, there can be listed: fused silica, crystalline silica, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, aluminum oxide, aluminum hydroxide, calcium silicate, aluminum silicate, preferably silicon dioxide, aluminum oxide, talc. These inorganic fillers can be used in combination of two or more.

[0100] When the average particle size of the inorganic filler is too large, it becomes an unfavorable factor that the gap between the upper and lower glass substrates cannot be well formed when manufacturing a narrow gap liquid crystal display unit, so it is appropriate to be below 2000nm, preferably below 1000nm, and more preferably below 300nm. In addition, the preferred lower limit is about 10nm, and more preferably about 100nm. The particle size can be measured using a laser diffraction / scattering particle size distribution analyzer (dry type) (manufactured by Qingxin Enterprise Co., Ltd.; LMS-30).

[0101] In the encapsulant for display of the present invention, when an inorganic filler is used, the amount of the inorganic filler is usually 5% to 50% by mass, preferably 5% to 40% by mass, in the total amount of the encapsulant for display. When the content of the inorganic filler is less than 5% by mass, the adhesive strength to the glass substrate is reduced, and the moisture resistance reliability is also poor, so the reduction in adhesive strength after moisture absorption is sometimes greater. In addition, when the content of the inorganic filler is more than 50% by mass, it is sometimes difficult to collapse due to the excessive filler content, and the gap of the liquid crystal cell cannot be formed.

[0102] [Silane coupling agent]

[0103] Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)-3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, and 3-chloropropyltrimethoxysilane. These silane coupling agents are sold in the form of KBM series and KBE series by Shin-Etsu Chemical Co., Ltd. and are easily available from the market. In the encapsulant for display of the present invention, when a silane coupling agent is used, the amount thereof is preferably 0.05 to 3% by mass based on the total amount of the encapsulant for display.

[0104] [Free Radical Polymerization Inhibitors]

[0105] The radical polymerization inhibitor is not particularly limited as long as it is a compound that reacts with radicals generated by a photoradical polymerization initiator, a thermal radical polymerization initiator, or the like to inhibit polymerization, and quinones, piperidines, hindered phenols, nitrosos, and the like can be used. Specific examples thereof include naphthoquinone, 2-hydroxynaphthoquinone, 2-methylnaphthoquinone, 2-methoxynaphthoquinone, 2,2,6,6-tetramethylpiperidin-1-oxyl, 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl, 2,2,6,6-tetramethyl-4-methoxypiperidin-1-oxyl, 2,2,6,6-tetramethyl-4-phenoxypiperidin-1-oxyl, hydroquinone, 2-methylhydroquinone, 2-methoxyhydroquinone, p-benzoquinone, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butylcresol, stearyl B-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiophene. bis(3-methyl-6-tert-butylphenol), 4,4'-butylenebis(3-methyl-6-tert-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, tetrakis-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenylpropionate)methane], 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione, p-methoxyphenol, 4-methoxy-1-naphthol, thiodiphenylamine, aluminum salt of N-nitrosophenylhydroxylamine, trade name ADK STAB LA-81, ADK STAB LA-82 (manufactured by ADK Co., Ltd.), etc., but not limited to these. Among them, naphthoquinone-based, hydroquinone-based, nitroso-based, and piperazine-based free radical polymerization inhibitors are preferred, naphthoquinone, 2-hydroxynaphthoquinone, hydroquinone, 2,6-di-tert-butyl-p-cresol, and POLYSTOP 7300P (manufactured by Hakuto Co., Ltd.) are more preferred, and POLYSTOP 7300P (manufactured by Hakuto Co., Ltd.) is most preferred.

[0106] The content of the radical polymerization inhibitor is preferably 0.0001 to 1% by mass, more preferably 0.001 to 0.5% by mass, and particularly preferably 0.01 to 0.2% by mass, based on the total amount of the encapsulant for a display of the present invention.

[0107] As an example of a method for obtaining the encapsulant for a display of the present invention, the following method can be cited. First, components (B) and (E) are dissolved in component (A) by heating as needed. Then, the mixture is cooled to room temperature, and then components (C), (D), (F), inorganic fillers, silane coupling agents, defoamers, leveling agents, solvents, etc. are added as needed, and the mixture is uniformly mixed using a known mixing device such as a three-roll mill, a sand mill, a ball mill, etc., and filtered using a metal mesh, thereby producing the encapsulant for a display of the present invention.

[0108] Moreover, the sealing agent for displays of the present invention is very useful as an adhesive for liquid crystal display cells, particularly as a liquid crystal sealing agent. An example of a liquid crystal display cell in the case of using the sealing agent for displays of the present invention as a liquid crystal sealing agent is shown below.

[0109] The liquid crystal display unit manufactured using the adhesive for the liquid crystal display unit of the present invention is obtained by the following method: a pair of substrates having a predetermined electrode formed on the substrate are arranged relative to each other at a predetermined interval, the surrounding is sealed with the liquid crystal sealant of the present invention, and a liquid crystal is sealed in the gap. The type of liquid crystal to be sealed is not particularly limited. Here, the substrate is composed of a composite substrate containing glass, quartz, plastic, silicon, etc., and at least one of which has light transmittance. As its preparation method, a spacer such as glass fiber is added to the liquid crystal sealant of the present invention (gap control material), and then the liquid crystal sealant is applied to one of the pair of substrates using a dispenser or a screen printing device, and then pre-cured at 80°C to 120°C as needed. Then, liquid crystal is dripped on the inner side of the cofferdam of the liquid crystal sealant, and another glass substrate is overlapped in a vacuum to form a gap. After the gap is formed, it is cured at 90°C to 130°C for 30 minutes to 2 hours, thereby obtaining the liquid crystal display unit of the present invention. In addition, when used in the form of a light-heat combined type, light curing is performed by irradiating ultraviolet rays to the liquid crystal sealant portion using an ultraviolet irradiator. The ultraviolet irradiation dose is preferably 500 mJ / cm 2 ~6000mJ / cm 2 , more preferably 1000 mJ / cm 2 ~4000mJ / cm 2(measurement wavelength: 365nm). Then, as needed, cure at 90°C to 130°C for 30 minutes to 2 hours, thereby obtaining the liquid crystal display unit of the present invention. The liquid crystal display unit of the present invention obtained in this way does not have poor display caused by liquid crystal contamination, and has excellent adhesiveness and moisture resistance reliability. As spacers, for example, glass fibers, silica microbeads, polymer microbeads, etc. The diameter thereof varies depending on the purpose, and is generally 2μm to 8μm, preferably 4μm to 7μm. Relative to 100 parts by mass of the liquid crystal sealant of the present invention, the amount of the spacer used is generally about 0.1 parts by mass to about 4 parts by mass, preferably about 0.5 parts by mass to about 2 parts by mass, and more preferably about 0.9 parts by mass to about 1.5 parts by mass.

[0110] The display encapsulant of the present invention is very suitable for use in adhesive applications in fields requiring curability, adhesion to various adherends, and moisture-heat-resistant reliability, such as liquid crystal sealants, encapsulants for organic electroluminescence, and adhesives for touch panels.

[0111] Example

[0112] The present invention is described in more detail below by way of examples, but the present invention is not limited to the examples. It should be noted that, unless otherwise specified, "parts" and "%" herein are based on mass.

[0113] [Synthesis example 1]

[0114] In a flask equipped with a thermometer, a condenser, and a stirring device, 351.25 g of a polyester polyol of 1,9-nonanediol, methyloctanediol, and adipic acid (O-1010 manufactured by Kuraray Co., Ltd., hydroxyl value 113.5 mgKOH / g), 347.88 g of a polyester polyol of methylpentanediol, adipic acid, and isophthalic acid (P-1012 manufactured by Kuraray Co., Ltd., hydroxyl value 114.6 mgKOH / g), and 197.99 g of toluene diisocyanate (CORONATE T-100 manufactured by Tosoh Corporation, molecular weight 174.2) were added and reacted at 80° C. The isocyanate content at this time was determined by adding an excess amount of amine and performing reverse titration with hydrochloric acid, and it was confirmed that the value was within the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value. Next, 0.6 g of p-methoxyphenol (polymerization inhibitor), 101.98 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.3 g of dibutyltin dilaurate (catalyst) were added, and the mixture was stirred at 80° C. to allow the reaction to proceed until the absorption spectrum of the isocyanate group (2280 cm -1 ) disappeared, thereby obtaining a urethane acrylate oligomer with a weight average molecular weight of 6900.

[0115] [Synthesis example 2]

[0116] In a flask equipped with a thermometer, a condenser, and a stirring device, 352.06 g of polycaprolactone diol (PLA 210 manufactured by Daicel Corporation, hydroxyl value 113.1 mgKOH / g), 347.45 g of polyester polyol of methylpentanediol, adipic acid, and isophthalic acid (P-1012 manufactured by Kuraray Corporation, hydroxyl value 114.6 mgKOH / g), and 197.74 g of toluene diisocyanate (CORONATE T-100 manufactured by Tosoh Corporation, molecular weight 174.2) were added and reacted at 80° C. The isocyanate content at this time was determined by adding an excess of amine and performing reverse titration with hydrochloric acid, and it was confirmed that the value was within the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value. Next, 0.6 g of p-methoxyphenol (polymerization inhibitor), 101.85 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.3 g of dibutyltin dilaurate (catalyst) were added, and the mixture was stirred at 80° C. to allow the reaction to proceed until the absorption spectrum of the isocyanate group (2280 cm -1 ) disappeared, thereby obtaining a urethane acrylate oligomer with a weight average molecular weight of 5200.

[0117] [Synthesis example 3]

[0118] In a flask equipped with a thermometer, a condenser, and a stirring device, 776.99 g of a polyester polyol of methylpentanediol, adipic acid, and isophthalic acid (P-2012 manufactured by Kuraray Co., Ltd., hydroxyl value 54.6 mgKOH / g) and 131.68 g of toluene diisocyanate (CORONATE T-100 manufactured by Tosoh Corporation, molecular weight 174.2) were added and reacted at 80° C. The isocyanate content at this time was determined by adding an excess of amine and performing reverse titration with hydrochloric acid, and it was confirmed that the value was within the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value. Next, 0.6 g of p-methoxyphenol (polymerization inhibitor), 90.43 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.3 g of dibutyltin dilaurate (catalyst) were added, and the mixture was stirred at 80° C. to allow the reaction to proceed until the absorption spectrum of the isocyanate group (2280 cm -1 ) disappeared, thereby obtaining a urethane acrylate oligomer with a weight average molecular weight of 6300.

[0119] [Synthesis Example 4]

[0120] In a flask equipped with a thermometer, a condenser, and a stirring device, 654.56 g of polycaprolactone diol (PLA 210 manufactured by Daicel Corporation, hydroxyl value 113.1 mgKOH / g) and 241.97 g of isophorone diisocyanate (VESTANATIPDI manufactured by Evonik, molecular weight 222.3) were added, and the reaction was carried out at 80°C. The isocyanate content at this time was determined by adding an excess of amine and performing reverse titration with hydrochloric acid, and it was confirmed that the value was within the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value. Next, 0.6 g of p-methoxyphenol (polymerization inhibitor), 102.57 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.3 g of dibutyltin dilaurate (catalyst) were added, and the mixture was stirred at 80°C, and the reaction was carried out until the absorption spectrum of the isocyanate group in the infrared absorption spectrum (2280 cm -1 ) disappeared, thereby obtaining a urethane acrylate oligomer with a weight average molecular weight of 5600.

[0121] [Synthesis Example 5]

[0122] In a flask equipped with a thermometer, a condenser, and a stirring device, 724.7 g of a polyester polyol of methylpentanediol and sebacic acid (P-2050 manufactured by Kuraray Co., Ltd., hydroxyl value 58.1 mgKOH / g), 31.56 g of tricyclodecane dimethanol (TCD ALCOHOL DM manufactured by Celanese Corporation, molecular weight 196.3) and 178.73 g of isophorone diisocyanate (VESTANATIPDI manufactured by Evonik, molecular weight 222.3) were added and reacted at 80° C. The isocyanate content at this time was determined by adding an excess of amine and performing reverse titration with hydrochloric acid, and it was confirmed that the value was within the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value. Next, 0.6 g of p-methoxyphenol (polymerization inhibitor), 64.11 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.3 g of dibutyltin dilaurate (catalyst) were added, and the mixture was stirred at 80° C. to allow the reaction to proceed until the absorption spectrum of the isocyanate group (2280 cm -1 ) disappeared, thereby obtaining a urethane acrylate oligomer with a weight average molecular weight of 11100.

[0123] [Synthesis example 6]

[0124] 100 parts (0.28 mol) of commercially available benzopinacol (manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in 350 parts of dimethylformaldehyde. 32 parts (0.4 mol) of pyridine as a base catalyst and 150 parts (0.58 mol) of BSTFA (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silylating agent were added thereto, and the temperature was raised to 70°C and stirred for 2 hours. The obtained reaction solution was cooled, and 200 parts of water were added while stirring to precipitate the product and deactivate the unreacted silylating agent. The precipitated product was separated by filtration and then washed thoroughly with water. The obtained product was then dissolved in acetone, and water was added for recrystallization and purification. 105.6 parts (yield 88.3%) of 1,2-bis(trimethylsilyloxy)-1,1,2,2-tetraphenylethane as the target product were obtained.

[0125] [Examples 1 to 6, Comparative Examples 1 to 4]

[0126] Components (A), (B), and (O) were mixed in the proportions shown in Table 1 below, component (E) was heated and dissolved at 90° C., and then cooled to room temperature, and components (C), (D), (F), and (O) were added, stirred, and then dispersed using a three-roll mill and filtered using a metal mesh (635 mesh) to prepare an encapsulant for a display.

[0127] [evaluate]

[0128] [Adhesive strength]

[0129] The alignment film liquid (Nissan Chemical Co., Ltd.: NRB-U738) was spin-coated on the glass substrate, pre-baked on a hot plate at 80°C for 3 minutes, and baked in an oven at 230°C for 30 minutes. Then, the substrate with the alignment film was irradiated with 500 mJ / cm by a UV irradiator. 2 The samples were then exposed to ultraviolet light (measurement wavelength: 254 nm) and baked in an oven at 230°C for 30 minutes.

[0130] 1 g of 5 μm glass fiber as a spacer was added to 100 g of the display encapsulant prepared in the examples and comparative examples and mixed and stirred. The display encapsulant was applied to a glass substrate coated with an alignment film in the form of replicating a 1 cm×1 cm corner, and the opposite alignment film-coated substrate was attached and irradiated with 3000 mJ / cm by a UV irradiator. 2 The glass substrate coated with the alignment film was exposed to ultraviolet light (measurement wavelength: 365 nm) and then placed in an oven for thermal curing at 130° C. for 40 minutes. The peeling adhesive strength of the glass substrate coated with the alignment film was measured by pressing the corner using an adhesion tester (manufactured by Seishin Shoji Co., Ltd.: SS-30WD). The strength is shown in Table 1.

[0131] [Moisture Permeability]

[0132] The encapsulants for displays prepared in the examples and comparative examples were sandwiched between polyethylene terephthalate (PET) films to form a 300 μm thick film, which was then irradiated with 3000 mJ / cm2 of UV light using a UV irradiator. 2 The film was exposed to ultraviolet light (measurement wavelength: 365 nm), and then placed in an oven for thermal curing at 130°C for 40 minutes. After curing, the PET film was peeled off to prepare a sample. The moisture permeability of the sample at 60°C and 90% was measured using a moisture permeability meter (manufactured by Lessy: L80-5000). The results are shown in Table 1.

[0133] [Elastic modulus]

[0134] The encapsulants for displays prepared in the examples and comparative examples were sandwiched between polyethylene terephthalate (PET) films to form a film with a thickness of 100 μm, and the film was irradiated with 3000 mJ / cm by a UV irradiator. 2 The samples were placed in an oven and heat cured at 130°C for 40 minutes. The PET film was peeled off after curing to prepare samples. The elastic modulus was measured by tensile testing the samples at room temperature (25°C) at a test speed of 5 mm / min using a Tensilon universal testing machine (RTG-1210 manufactured by A&D Co., Ltd.). The results are shown in Table 1.

[0135]

[0136] A-1: Urethane acrylate obtained in Synthesis Example 1

[0137] A-2: Urethane acrylate obtained in Synthesis Example 2

[0138] A-3: Urethane acrylate obtained in Synthesis Example 3

[0139] A-4: Urethane acrylate obtained in Synthesis Example 4

[0140] A-5: Urethane acrylate obtained in Synthesis Example 5

[0141] B-1: Bisphenol A epoxy resin acrylate

[0142] (Synthesized by a common synthesis method, for example, the reaction of Synthesis Example 6 in Japanese Patent Application Laid-Open No. 2016-24243)

[0143] B-2: Partially acrylated bisphenol A epoxy resin

[0144] (Synthesized by a common synthesis method, for example, reacting 50% equivalent of acrylic acid in Synthesis Example 6 of JP-A-2016-24243)

[0145] B-3: o-phenylphenoxyethyl acrylate (manufactured by MIWON: Miramer M-1142)

[0146] C-1: polymethacrylate organic fine particles (manufactured by AICA INDUSTRY CO., LTD., trade name "F-351S")

[0147] D-1: Tris(2-hydrazinocarbonylethyl)isocyanurate finely pulverized product

[0148] (Manufactured by Nippon Finechem Co., Ltd.: HCIC, finely pulverized into an average particle size of 1.5 μm using a jet mill)

[0149] E-1: Irgacure OXE04 (manufactured by BASF)

[0150] E-2: 2,4-diethylthioxanthone (trade name "KAYACURE-DETX-S" manufactured by Nippon Kayaku Co., Ltd.)

[0151] F-1: 1,2-bis(trimethylsilyloxy)-1,1,2,2-tetraphenylethane

[0152] (Synthesis Example 6: Material finely pulverized into an average particle size of 1.9 μm using a jet mill)

[0153] O-1: 3-Glycidoxypropyltrimethoxysilane (manufactured by JNC Corporation: SILA-ACE S-510)

[0154] O-2: Spherical silica (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: X-24-9163A; primary average particle size: 0.1 μm)

[0155] O-3: Spherical silica (manufactured by Tokuyama Co., Ltd., SANSIL SSP-07M; primary average particle size 0.7 μm)

[0156] O-4: Tris(3-carboxyethyl)isocyanurate

[0157] (Manufactured by Shikoku Chemical Industry Co., Ltd.: CIC acid, finely pulverized into an average particle size of 1.5 μm using a jet mill)

[0158] O-5: 2,4-Diamino-6-[2'-methylimidazole-(1')]-ethyl-s-triazine·isocyanuric acid adduct

[0159] (Manufactured by Shikoku Chemical Co., Ltd.: 2MA-OK-PW)

[0160] O-6: Nitroso piperidine derivative (manufactured by Hakuto Co., Ltd.: POLYSTOP 7300P)

[0161] From the results in Table 1, it was confirmed that the encapsulant for a display of the present invention has both flexibility and low moisture permeability and is also excellent in adhesive strength.

[0162] Industrial Applicability

[0163] The encapsulant for a display of the present invention has excellent adhesive strength with an adherend and has both flexibility and low moisture permeability, and therefore can be used as an encapsulant for displays requiring adhesion to organic films, flexible displays, and curved displays.

Claims

1. A display encapsulant, in, The encapsulant for a display comprises (A) urethane (meth)acrylate, wherein the urethane (meth)acrylate is obtained by reacting (a) a polyol having an aromatic ring, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate. A polyester polyol containing methylpentanediol, adipic acid and isophthalic acid is used as the (a) polyol having an aromatic ring.

2. The encapsulant for a display according to claim 1, in, The encapsulant for a display further contains a component (B) a curable compound.

3. The encapsulant for a display according to claim 2, in, The component (B) is a partial epoxy (meth)acrylate.

4. The encapsulating agent for a display according to any one of claims 1 to 3, in, The encapsulant for a display further contains a component (C) an organic filler.

5. The encapsulant for a display according to claim 4, in, The component (C) is one or more organic fillers selected from the group consisting of polyurethane particles, acrylic polymer particles, styrene polymer particles, styrene-olefin copolymer particles and polysiloxane particles.

6. The encapsulating agent for a display according to any one of claims 1 to 3 and 5, in, The encapsulant for a display further contains a component (D) a thermosetting agent.

7. The encapsulating agent for a display according to any one of claims 1 to 3 and 5, in, The encapsulant for a display further contains a component (E) a photoradical polymerization initiator.

8. The encapsulating agent for a display according to any one of claims 1 to 3 and 5, in, The encapsulant for a display further contains a component (F) which is a thermal radical polymerization initiator.

9. The encapsulant for a display according to claim 8, in, The component (F) is a thermal radical polymerization initiator that does not contain an oxygen-oxygen bond (-OO-) and a nitrogen-nitrogen bond (-N=N-) in the molecule.

10. The encapsulating agent for a display according to any one of claims 1 to 3 and 5, in, The encapsulant for a display is a liquid crystal sealant for a liquid crystal dropping method.

11. A liquid crystal display, in, The liquid crystal display is sealed with a liquid crystal sealant using the liquid crystal dropping method according to claim 10.

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