Sheet-like sealing material

Abstract

To provide a sheet-like sealing material capable of bonding members to each other at a low temperature in a short time.SOLUTION: The sheet-like sealing material includes an alicyclic epoxy compound, an epoxy compound which is solid at 25 °C, a photocationic polymerization initiator, and a photocuring retarder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a sheet-shaped sealing material. [Background technology]

[0002] In recent years, display devices with foldable display surfaces have been developed. While such display devices require foldability, they are also required to maintain the panel flat (flatness maintenance). However, achieving both foldable flexibility and high flatness maintenance is difficult, and various studies have been conducted. One method proposed for achieving both foldability and flatness maintenance is to attach a resin film, a metal plate, or the like to the back side of a display element via an adhesive layer (for example, Patent Document 1).

[0003] Meanwhile, various compositions are known as adhesives for general display devices. For example, liquid adhesives and sheet-like adhesives (referred to herein as "sheet-like sealing materials") are known. Among these, sheet-like sealing materials can not only bond two components together, but also impart appropriate strength to the sheet-like sealing material itself and provide stress relaxation performance to the sheet-like sealing material. Therefore, the use of sheet-like sealing materials is expected to enable the production of higher-performance display devices using fewer components. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-61186 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, even in the above-mentioned foldable display device, it is considered to bond the display element and a resin film, metal panel, or the like disposed on the back side thereof via a sheet-shaped sealing material. However, most conventional sheet-shaped sealing materials are thermosetting sheet-shaped sealing materials, which usually require heating at 100°C or higher for curing. On the other hand, the display elements (e.g., organic EL elements) used in foldable display devices have a heat resistance of about 100°C, which means that there are limitations on the heating temperature and heating time during device assembly. Therefore, there has been a problem in that it is difficult to apply a thermosetting sheet-shaped sealing material to bonding a resin film, metal panel, or the like.

[0006] On the other hand, photocurable sheet-type sealing materials are also known and their application is also considered. However, the TFT substrate of a display element (e.g., an organic EL element) is usually opaque. Furthermore, the metal plate or resin film placed on the back side of the display element is often also opaque. Therefore, it has been difficult to apply photocurable sheet-type sealing materials to bonding resin films, metal panels, etc.

[0007] Therefore, an object of the present invention is to provide a sheet-like sealing material that can bond two members together at low temperature in a short time. [Means for solving the problem]

[0008] That is, the present invention provides the following sheet-like sealing material. [1] A sheet-like sealing material comprising an alicyclic epoxy compound, an epoxy compound that is solid at 25°C, a photocationic polymerization initiator, and a photocure retarder. [2] The sheet-like sealing material according to [1], wherein the photocuring retarder is a hindered amine. [3] The sheet-like sealing material according to [1] or [2], further comprising a photosensitizer. [4] The sheet-like sealing material according to any one of [1] to [3], which has a thickness of 5 μm or more and 50 μm or less. [Effects of the Invention]

[0009] The sheet-shaped sealing material of the present invention makes it possible to bond two members together at low temperature in a short time. DETAILED DESCRIPTION OF THE INVENTION

[0010] The sheet-like sealing material of the present invention is suitably used as an interlayer adhesive for bonding two members of a display device together or filling the gap between them, although the use of the sheet-like sealing material of the present invention is not limited to this use.

[0011] As mentioned above, heat-curable sheet-type sealing materials need to be heated to a relatively high temperature, and it is difficult to cure them at a low temperature in a short time. On the other hand, photo-curable sheet-type sealing materials require that the components to be bonded have optical transparency, and it is difficult to bond components that do not have optical transparency. Furthermore, general photo-curable sheet-type sealing materials cure immediately after being irradiated with light. Therefore, it is necessary to irradiate light while the sheet-type sealing material and the components to be bonded are in close contact with each other.

[0012] In contrast, the sheet-shaped sealing material of the present invention contains a photo-cationic polymerization initiator and a photo-curing retarder, and therefore the time from light irradiation until the sheet-shaped sealing material cures is long. Therefore, after irradiating the sheet-shaped sealing material with light, the sheet-shaped sealing material can be closely attached to a desired member. In other words, even if neither of the two members to be bonded has optical transparency, they can be bonded together. Furthermore, the sheet-shaped sealing material of the present invention is further cured by further heating after light irradiation, but at this time, the sheet-shaped sealing material has already undergone a certain degree of curing reaction due to the previous light irradiation. Therefore, sufficient curing can be achieved without increasing the heating temperature or heating for a long period of time. Therefore, the sheet-shaped sealing material of the present invention allows two members to be bonded together at a low temperature in a short time.

[0013] The sheet-like sealing material only needs to contain at least (A) an alicyclic epoxy compound, (B) an epoxy compound that is solid at 25°C, (C) a photocationic polymerization initiator, and (D) a photocuring retarder, and may further contain other components as necessary. Examples of other components include (E) a photosensitizer, (F) other resin components, and (G) various additives. The components contained in the sheet-like sealing material, their physical properties, and manufacturing methods will be described in detail below.

[0014] (A) Alicyclic epoxy compound In this specification, an epoxy compound refers to a compound having one or more epoxy groups and an alicyclic structure in one molecule. The (A) alicyclic epoxy compound is preferably a compound that is liquid at room temperature (25°C). The number of epoxy groups contained in the (A) alicyclic epoxy compound is preferably 2 or more, more preferably 2 to 4. The sheet-like sealing material may contain only one type of (A) alicyclic epoxy compound, or may contain two or more types.

[0015] Examples of (A) alicyclic epoxy compounds include compounds having a cycloalkene oxide structure represented by the following general formula: The cycloalkene oxide structure is a structure obtained by epoxidizing a cycloalkene with an oxidizing agent such as a peroxide, and has an aliphatic ring and an epoxy group composed of two carbon atoms and an oxygen atom that constitute the aliphatic ring. [ka] In the above general formula, M represents an alicyclic structure, and the number of carbon atoms therein is preferably 4 to 8, and more preferably 5 to 6. When the number of carbon atoms in the alicyclic structure of the cycloalkene oxide structure is within this range, the compatibility of (A) the alicyclic epoxy compound with other components tends to be good.

[0016] Specific examples of the cycloalkene oxide structure include cyclohexene oxide and cyclopentene oxide, with cyclohexene oxide being preferred.

[0017] The number of cycloalkene oxide structures contained in one molecule of the (A) alicyclic epoxy compound may be one (monofunctional) or two or more (polyfunctional), and among these, the number of cycloalkene oxide structures contained in one molecule of the alicyclic epoxy compound is preferably two or more (polyfunctional).

[0018] Examples of the (A) alicyclic epoxy compound having a cycloalkene oxide structure include compounds represented by the following general formulas (a-1) to (a-3).

[0019] [ka]

[0020] M in the above general formula (a-1) 1 and M 2 represents an alicyclic structure, and as described above, the number of carbon atoms therein is preferably 4 to 8, more preferably 5 to 6. X in the above general formula (a-1) 1 is a single bond or a linking group. Examples of the linking group include a divalent hydrocarbon group, a carbonyl group, an ether group (ether bond), a thioether group (thioether bond), an ester group (ester bond), a carbonate group (carbonate bond), an amide group (amide bond), or a group in which multiple of these are linked together.

[0021] Examples of divalent hydrocarbon groups that can be the linking group include alkylene groups having 1 to 18 carbon atoms and divalent alicyclic hydrocarbon groups. Examples of alkylene groups having 1 to 18 carbon atoms include methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene. Examples of divalent alicyclic hydrocarbon groups include divalent cycloalkylene groups (including cycloalkylidene groups) such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene.

[0022] Among them, X 1is preferably a single bond or a linking group having an oxygen atom. The linking group having an oxygen atom is more preferably -CO- (carbonyl group), -O-CO-O- (carbonate group), -COO- (ester group), -O- (ether group), -CONH- (amide group), a group in which a plurality of these groups are linked together, or a group in which one or more of these groups are linked to one or more divalent hydrocarbon groups.

[0023] Specific examples of the alicyclic epoxy compound represented by general formula (a-1) include the following compounds. In the following formula, l is an integer of 1 to 10, and m is an integer of 1 to 30. R is an alkylene group having 1 to 8 carbon atoms (preferably an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, a propylene group, or an isopropylene group). n1 and n2 are each an integer of 1 to 30.

[0024] [ka]

[0025] Examples of commercially available alicyclic epoxy compounds represented by the general formula (a-1) include Celloxide 2021P, Celloxide 2081, Celloxide 8000, and Celloxide 8010 (manufactured by Daicel Corporation).

[0026] As described above, the (A) alicyclic epoxy compound may be, for example, a compound having a structure represented by the following general formula (a-2) or (a-3). [ka] M in the above general formulae (a-2) and (a-3) 3 , M 4 , and M 5 represents an alicyclic structure, and the number of carbon atoms therein is preferably 4 to 8, and more preferably 5 to 6. X in the above general formula (a-3) 2is a single bond or a linking group. The linking group is the same as the linking group in the above-mentioned general formula (a-1). In addition, the compounds represented by general formulas (a-2) and (a-3) may have an alkyl group or the like bonded to a carbon that constitutes an alicyclic structure or an epoxy group.

[0027] Examples of the alicyclic epoxy compounds represented by the general formula (a-2) or (a-3) include 3,4:7,8-diepoxybicyclo[4.3.0]nonane, limonene dioxide, etc. Commercially available examples of these compounds include THI-DE (manufactured by JX-TG Corporation) and LDO (manufactured by Nagase Chemtec Corporation).

[0028] In any of the above-mentioned (A) alicyclic epoxy compounds, the weight-average molecular weight is preferably 180 or more, more preferably 190 or more, and even more preferably 200 or more. The upper limit of the weight-average molecular weight is appropriately selected depending on the desired viscosity of the sheet-like sealing material, but is preferably 500 or less. When the weight-average molecular weight of the alicyclic epoxy compound is 180 or more, the sheet-like sealing material becomes easy to handle. The weight-average molecular weight of the (A) alicyclic epoxy compound is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0029] From the viewpoints of compatibility with other components and the likelihood that the sheet-shaped sealing material will have the desired physical properties, the (A) alicyclic epoxy compound is particularly preferably a compound represented by the following formula: In addition, the alicyclic epoxy compound has low viscosity when uncured, which improves the handleability of the sheet-shaped sealing material. [ka]

[0030] The total amount of the (A) alicyclic epoxy compound relative to the total amount of the sheet-like sealing material is preferably 20% by mass to 50% by mass, more preferably 30% by mass to 40% by mass. When the amount of the (A) alicyclic epoxy compound is within this range, the sheet-like sealing material tends to be easy to handle and the adhesive strength between the sheet-like sealing material and various components tends to be good.

[0031] (B) Epoxy compound that is solid at 25°C The epoxy compound that is solid at 25°C (hereinafter also referred to simply as "solid epoxy compound") may be a compound that has at least one epoxy group in the molecule and is solid at 25°C (excluding those corresponding to the above-mentioned (A) alicyclic epoxy compound). The sheet-like sealing material may contain only one type of (B) solid epoxy compound, or may contain two or more types. When the sheet-like sealing material contains the (B) solid epoxy compound, the shape stability of the sheet-like sealing material is likely to be improved, and the sheet shape is easily maintained. Furthermore, when the sheet-like sealing material contains the (B) epoxy compound that is solid at 25°C, the elastic modulus of the sheet-like sealing material is likely to fall within the desired range.

[0032] The weight-average molecular weight of the solid epoxy (B) is preferably 500 to 50,000, more preferably 800 to 30,000, and even more preferably 1,000 to 20,000. When the molecular weight of the solid epoxy compound is within this range, the elastic modulus of the sheet-like epoxy compound tends to fall within the desired range. The weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0033] The (B) solid epoxy compound may be an aromatic epoxy compound or an aliphatic epoxy compound, but an aromatic epoxy compound is more preferred.

[0034] Specific examples of aromatic epoxy compounds that can be the (B) solid epoxy compound include bisphenol-type epoxy resins such as bisphenol A, bisphenol F, bisphenol E, bisphenol S, bisphenol AD, and mixtures thereof; diphenyl ether-type epoxy resins; novolac-type epoxy resins such as phenol novolac, cresol novolac, biphenyl novolac, bisphenol novolac, naphthol novolac, trisphenol novolac, and dicyclopentadiene novolac; biphenyl-type epoxy resins; naphthyl-type epoxy resins; triphenolalkane-type epoxy resins such as triphenolmethane, triphenolethane, and triphenolpropane; etc. Of the above, bisphenol-type epoxy resins or biphenyl-type epoxy resins are preferred as the aromatic epoxy compound.

[0035] The number of epoxy groups in the (B) solid epoxy compound is not particularly limited, but the epoxy equivalent is preferably 250 g / eq to 25,000 g / eq, more preferably 500 g / eq to 10,000 g / eq. When the epoxy equivalent of the (B) solid epoxy compound is 500 g / eq or more, the tackiness of the sheet-like sealing material at room temperature is reduced. Therefore, the handling ability is likely to be improved when manufacturing a display device using the sheet-like sealing material. On the other hand, if the epoxy equivalent of the (B) solid epoxy compound is excessively large, the solubility of the (B) solid epoxy compound in solvents may decrease, or the compatibility with the (A) alicyclic epoxy compound described above may become poor. Therefore, the epoxy equivalent of the (B) solid epoxy compound is preferably 25,000 g / eq or less.

[0036] The total amount of the (B) solid epoxy compound relative to the total amount of the sheet-like sealing material is preferably 30% by mass to 80% by mass, more preferably 40% by mass to 70% by mass. When the amount of the (B) solid epoxy compound is within this range, the sheet-like sealing material tends to be easy to handle, and the adhesive strength between the sheet-like sealing material and various components tends to be good.

[0037] (C) Photocationic polymerization initiator The (C) photocationic polymerization initiator may be any compound that generates cations upon irradiation with light, and the type is not particularly limited as long as it is a compound that can cure the above-mentioned (A) alicyclic epoxy compound or (B) solid epoxy compound. The sheet-like sealing material may contain only one type of (C) photocationic polymerization initiator, or may contain two or more types.

[0038] The wavelength of light that can be absorbed by the (C) cationic photopolymerization initiator, i.e., the wavelength of light at which the (C) cationic photopolymerization initiator generates cations, is appropriately selected depending on the curing method of the sheet-like sealing material, but is usually preferably 300 nm or more, and more preferably 300 to 450 nm.

[0039] The cation generated by the (C) photocationic polymerization initiator may be any monovalent cation, and includes an oxonium ion, an ammonium ion, a sulfonium ion, an iodonium ion, or the like.

[0040] Examples of oxonium ions include oxonium ions such as trimethyloxonium, diethylmethyloxonium, triethyloxonium, and tetramethylenemethyloxonium; pyrilinium ions such as 4-methylpyrilinium, 2,4,6-trimethylpyrilinium, 2,6-di-tert-butylpyrilinium, and 2,6-diphenylpyrilinium; and chromium and isochromen ions such as 2,4-dimethylchromenium and 1,3-dimethylisochromenium.

[0041] Examples of ammonium ions include pyrrolidinium ions such as N,N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, and N,N-diethylpyrrolidinium; imidazolinium ions such as N,N'-dimethylimidazolinium, N,N'-diethylimidazolinium, N-ethyl-N'-methylimidazolinium, 1,3,4-trimethylimidazolinium, and 1,2,3,4-tetramethylimidazolinium; tetrahydropyrimidinium ions such as N,N'-dimethyltetrahydropyrimidinium; morpholinium ions such as N,N'-dimethylmorpholinium; ions of piperidinium such as N'-diethylpiperidinium; pyridinium ions such as N-methylpyridinium, N-benzylpyridinium, and N-phenacylpyridinium; imidazolium ions such as N,N'-dimethylimidazolium; quinolium ions such as N-methylquinolium, N-benzylquinolium, and N-phenacylquinolium; isoquinolium ions such as N-methylisoquinolium; thiazonium ions such as benzylbenzothiazonium and phenacylbenzothiazonium; acridium ions such as benzylacridium and phenacylacridium; and the like.

[0042] Examples of the phosphonium ion include tetraarylphosphonium ions such as tetraphenylphosphonium, tetra-p-tolylphosphonium, tetrakis(2-methoxyphenyl)phosphonium, tetrakis(3-methoxyphenyl)phosphonium, and tetrakis(4-methoxyphenyl)phosphonium; triarylphosphonium ions such as triphenylbenzylphosphonium, triphenylphenacylphosphonium, triphenylmethylphosphonium, and triphenylbutylphosphonium; and tetraalkylphosphonium ions such as triethylbenzylphosphonium, tributylbenzylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, tetrahexylphosphonium, triethylphenacylphosphonium, and tributylphenacylphosphonium; and the like.

[0043] Examples of sulfonium ions include triphenylsulfonium, tri-p-tolylsulfonium, tri-o-tolylsulfonium, tris(4-methoxyphenyl)sulfonium, 1-naphthyldiphenylsulfonium, 2-naphthyldiphenylsulfonium, tris(4-fluorophenyl)sulfonium, tri-1-naphthylsulfonium, tri-2-naphthylsulfonium, tris(4-hydroxyphenyl)sulfonium, 4-(phenylthio)phenyldiphenylsulfonium, 4-(p-tolylthio)phenyldi-p-tolylsulfonium, 4-(4-methoxyphenylthio)phenylbis(4-methoxyphenyl)sulfonium, 4-(phenylthio)phenylbis(4-methoxyphenyl)sulfonium, 4-(phenylthio)phenylbis(4-methoxyphenyl)sulfonium, 4-(phenylthio)phenyldi-p-tolylsulfonium, [4-(4-biphenylylthio)phenyl]-4-biphenylylphenylsulfonium, [4-(2-thioxanthonylthio)phenyl )phenyl]diphenylsulfonium, bis[4-(diphenylsulfonio)phenyl]sulfide, bis[4-{bis[4-(2-hydroxyethoxy)phenyl]sulfonio}phenyl]sulfide, bis{4-[bis(4-fluorophenyl)sulfonio]phenyl}sulfide, bis{4-[bis(4-methylphenyl)sulfonio]phenyl}sulfide, bis{4-[bis(4-methoxyphenyl)sulfonio]phenyl}sulfide, 4-(4-benzoyl-2-chlorophenyl) 4-(4-benzoyl-2-chlorophenylthio)phenyldiphenylsulfonium, 4-(4-benzoylphenylthio)phenylbis(4-fluorophenyl)sulfonium, 4-(4-benzoylphenylthio)phenyldiphenylsulfonium, 4-(4-benzoylphenylthio)phenyldiphenylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracen-2-yldi-p-tolylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracen-2-yldi-p-tolylsulfonium,10-Dihydroanthracen-2-yldiphenylsulfonium, 2-[(di-p-tolyl)sulfonio]thioxanthone, 2-[(diphenyl)sulfonio]thioxanthone, 4-(9-oxo-9H-thioxanthen-2-yl)thiophenyl-9-oxo-9H-thioxanthen-2-ylphenylsulfonium, 4-[4-(4-tert-butylbenzoyl)phenylthio]phenyldi-p-tolylsulfonium, 4-[4-(4-tert-butylbenzoyl)phenylthio]phenyldiphenylsulfonium, 4-[4-(benzoylphenylthio)]phenyldi-p-tolylsulfonium, 4-[4-(benzoylphenylthio)]phenyldiphenylsulfonium, 5-(4-methoxyphenyl)thioanthrenium, 5-phenylthioanthrenium, 5-tolylthioanthrenium, 5-(4-ethoxyphenyl)thioanthrenium, 5-(2,4,Triarylsulfonium ions such as (6-trimethylphenyl)thioanthrenenium; diarylsulfonium ions such as diphenylphenacylsulfonium, diphenyl-4-nitrophenacylsulfonium, diphenylbenzylsulfonium, and diphenylmethylsulfonium; phenylmethylbenzylsulfonium, 4-hydroxyphenylmethylbenzylsulfonium, 4-methoxyphenylmethylbenzylsulfonium, 4-acetocarbonyloxyphenylmethylbenzylsulfonium, 4-hydroxyphenyl(2-naphthylmethyl)methylsulfonium, 2-naphthylmethylbenzylsulfonium, and 2-naphthylmethyl(1-ethoxycarbonyl)ethylsulfonium ions of monoarylsulfonium such as phenylmethylphenacylsulfonium, 4-hydroxyphenylmethylphenacylsulfonium, 4-methoxyphenylmethylphenacylsulfonium, 4-acetocarbonyloxyphenylmethylphenacylsulfonium, 2-naphthylmethylphenacylsulfonium, 2-naphthyloctadecylphenacylsulfonium, and 9-anthracenylmethylphenacylsulfonium; ions of trialkylsulfonium such as dimethylphenacylsulfonium, phenacyltrhydrothiophenium, dimethylbenzylsulfonium, benzyltetrahydrothiophenium, and octadecylmethylphenacylsulfonium; and the like.

[0044] Examples of iodonium ions include diphenyliodonium, di-p-tolyliodonium, bis(4-dodecylphenyl)iodonium, bis(4-methoxyphenyl)iodonium, (4-octyloxyphenyl)phenyliodonium, bis(4-decyloxy)phenyliodonium, 4-(2-hydroxytetradecyloxy)phenylphenyliodonium, 4-isopropylphenyl(p-tolyl)iodonium, 4-isobutylphenyl(p-tolyl)iodonium, and the like.

[0045] Among the above cations, ammonium ions, phosphonium ions, sulfonium ions, or iodonium ions are more preferred, sulfonium ions or iodonium ions are even more preferred, and sulfonium ions are even more preferred. Among sulfonium ions, triarylsulfonium ions are preferred.

[0046] On the other hand, the type of counter anion that forms a salt with the cation of the photocationic polymerization initiator (C) is not particularly limited, but the anion preferably contains a central atom and a ligand coordinated to the central atom. Examples of the central atom include P, As, Sb, and Ga. Examples of the ligand include F. - and Cl - , (CF2CF3) n F (6-n) , a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and the like.

[0047] Examples of preferred structures of the counter anion include PF6 - , (CF2CF3) n PF (6-n) - , AsF6 - , SbF6 - , BF4 - , SbCl6 - , (C6F6)4B - etc. are included.

[0048] The (C) photocationic polymerization initiator may be a commercially available product. A suitable commercially available example of the (C) photocationic polymerization initiator is CPI-210S ((CF2CF3)) manufactured by San-Apro Co., Ltd. n PF (6-n) - (triarylsulfonium salts with a counter anion) and the like.

[0049] The total amount of (C) cationic photopolymerization initiator relative to the total amount of the sheet-like sealing material is preferably 0.5% by mass or more and 5% by mass or less, and more preferably 1% by mass or more and 3% by mass or less. When the amount of (C) cationic photopolymerization initiator is within this range, the photocurability of the sheet-like sealing material tends to be good, and the adhesive strength between the sheet-like sealing material and various members tends to be good.

[0050] (D) Photocuring retarder (D) Photocuring retarder is a component for controlling the time required for photocuring of the sheet-like sealing material. Examples of the photocuring retarder include hindered amines, benzotriazole-based compounds, triazine-based compounds, benzophenone-based compounds, benzoate-based compounds, propanediol-based compounds, and oxanilide-based compounds. The sheet-like sealing material may contain only one type of (D) photocuring retarder, or may contain two or more types.

[0051] Examples of the hindered amine compound include compounds having a 2,2,6,6-tetramethylpiperidine skeleton.Specific examples include TINUVIN 111FDL (manufactured by BASF), bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate (manufactured by BASF under the trade name TINUVIN 123), TINUVIN 144 (manufactured by BASF), TINUVIN 292 (manufactured by BASF), TINUVIN 765 (manufactured by BASF), TINUVIN 770 (manufactured by BASF), N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate (manufactured by BASF under the trade name CHIMASSORB119FL), (manufactured by BASF)), trade name CHIMASSORB2020FDL (manufactured by BASF), dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (trade name CHIMASSORB622LD (manufactured by BASF)), poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyllauryl-4-piperidyl)imino}] (trade name CHIMASSORB944FD (manufactured by BASF)), trade name Sanduvor 3050 Liq. (manufactured by Clariant Japan), trade name Sanduvor3052 Liq. (manufactured by Clariant Japan), trade name Sanduvor3058 Liq. (manufactured by Clariant Japan), trade name Sanduvor3051 Powder. (manufactured by Clariant Japan), trade name Sanduvor3070 Powder. (manufactured by Clariant Japan), trade name VP Sanduvor PR-31 (manufactured by Clariant Japan), trade name Hostavin N20 (manufactured by Clariant Japan), trade name Hostavin N24 (manufactured by Clariant Japan), trade name Hostavin N30 (manufactured by Clariant Japan), trade name Hostavin N321 (manufactured by Clariant Japan), trade name Hostavin PR-31 (manufactured by Clariant Japan), trade name Hostavin 845 (manufactured by Clariant Japan), trade name Nylostab S-EED (manufactured by Clariant Japan), and the like.

[0052] On the other hand, specific examples of benzotriazole compounds include 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalividylmethyl)phenol, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4-tert-butylphenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-butylphenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl)phenol, 2-(2H-benzotriazol-2-yl)-4-(3-one-4-oxa-dodecyl)-6-tert-butyl-phenol, 2-{5-chloro(2H)-benzotriazol-2-yl}-4-(3-one-4-oxa-dodecyl)-6-tert-butyl-phenol, 2-{5-chloro(2H)-benzotriazol-2-yl}-4-methyl-6-tert-butyl-phenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-{5-chloro(2H)-benzotriazol-2-yl}-4,6-Di-tert-butylphenol, 2-(2H-benzotriazol-2-yl)-4-tert-octylphenol, 2-(2H-benzotriazol-2-yl)-4-methyl-6-n-dodecylphenol, 3-[3-tert-butyl-5-(5-chloro-2H-benzotriazol-2-yl)-4-hydroxyphenyl]octyl propionate, 3-[3-tert-butyl-5-(5-chloro-2H-benzotriazol-2-yl)-4-hydroxyphenyl] Examples of suitable surfactants include 2-ethylhexyl propionate, a reaction product of methyl-3-{3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl}propionate / polyethylene glycol 300, Viosorb 583 (Kyodo Pharmaceuticals), Tinuvin 326 (BASF), Tinuvin 384-2 (BASF), Tinuvin PS (BASF), Seesorb 706 (Shipro Chemicals), and EVERSORB 109 (EVER LIGHT).

[0053] Specific examples of the triazine compound include 2-(4-phenoxy-2-hydroxy-phenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-oxa-hexadecyloxy)-4,6-di(2,4-dimethyl-phenyl)-1,3,5-triazine, 2-(2-hydroxy-4-oxa-heptadecyloxy)-4,6-di(2,4-dimethyl-phenyl)-1,3,5-triazine, 2-(2-hydroxy-4-iso-octyloxy-phenyl)-4,6-di(2,4-dimethyl-phenyl)-1,3,5-triazine, Tinuvin 400 (manufactured by BASF), Tinuvin 405 (manufactured by BASF), Tinuvin 460 (manufactured by BASF), Tinuvin 479 (manufactured by BASF), and the like.

[0054] Examples of the benzophenone compounds include 2-hydroxy-4-n-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, etc. Specific examples of the benzoate compounds include 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, etc.

[0055] Specific examples of propanediocic acid ester compounds include propanediocic acid-{(4-methoxyphenyl)-methylene}-dimethyl ester, trade name Hostavin PR-25 (manufactured by Clariant Japan), trade name Hostavin B-CAP (manufactured by Clariant Japan), etc. Examples of oxanilide compounds include 2-ethyl-2'-ethoxy-oxanilide, trade name Sanduvor VSU (manufactured by Clariant Japan), etc.

[0056] Among the above, hindered amines are particularly preferred from the viewpoint that they can appropriately suppress photocuring of the sheet-like sealing material.

[0057] The total amount of (D) photocuring retarder relative to the total amount of the sheet-like sealing material is selected appropriately depending on the type of (D) photocuring retarder, but is preferably 0.5% by mass to 5% by mass, more preferably 1% by mass to 3% by mass. When the amount of (D) photocuring retarder is within this range, the photocurability of the sheet-like sealing material tends to fall within an appropriate range. In particular, the amount of (D) photocuring retarder is preferably 20 parts by mass to 500 parts by mass, more preferably 30 parts by mass to 400 parts by mass, per 100 parts by mass of cationic photopolymerization initiator. When the amount of (D) photocuring retarder is within this range relative to the amount of (C) cationic photopolymerization initiator, the photocurability is more easily controlled.

[0058] (E) Photosensitizer The sheet-like sealing material preferably contains a photosensitizer (E). The type of the photosensitizer (E) is appropriately selected depending on the type of the cationic photopolymerization initiator (D), and among these, a compound that becomes excited by light with a wavelength of 300 nm to 450 nm is preferred. The sheet-like sealing material may contain only one type of photosensitizer (E), or may contain two or more types.

[0059] Examples of (E) photosensitizers include polynuclear aromatics such as pyrene, perylene, triphenylene, and anthracene; xanthenes such as fluorescein, eosin, erythrosine, rhodamine B, and rose bengal; xanthones such as xanthone, thioxanthone, dimethylthioxanthone, and diethylthioxanthone; cyanines such as thiacarbocyanine and oxacarbocyanine; merocyanines such as merocyanine and carbomerocyanine; rhodacyanines; oxonols; thiazines such as thionine, methylene blue, and toluidine blue; acridines such as acridine orange, chloroflavin, and acriflavine; acridones such as acridone and 10-butyl-2-chloroacridone; anthraquinones; squaryliums; styryls; base styryls; and coumarins such as 7-diethylamino-4-methylcoumarin. Among these, polycyclic aromatic compounds, acridones, coumarins, and base styryls are particularly preferred, and anthracene compounds are particularly preferred.

[0060] The total amount of (E) photosensitizer relative to the total amount of the sheet-like sealing material is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 2% by mass or less. When the amount of (E) photosensitizer is within this range, the photocurability of the sheet-like sealing material can be easily adjusted to an appropriate range. From the viewpoint of adjusting the photocurability of the sheet-like sealing material, the total amount of (E) photosensitizer is preferably 10 parts by mass or more and 100 parts by mass or less, and more preferably 25 parts by mass or more and 75 parts by mass or less, relative to 100 parts by mass of the total amount of (C) photocationic polymerization initiator.

[0061] (F) Other resin components The sheet-like sealing material may contain resin components other than the above-mentioned (A) alicyclic epoxy compound and (B) solid epoxy compound, as long as the object and effect of the present invention are not impaired. Examples of other resin components include epoxy compounds that are liquid at room temperature (25°C) (hereinafter also referred to as "liquid epoxy compounds"). Examples of such liquid epoxy compounds include aromatic epoxy compounds and aliphatic epoxy compounds. The sheet-like sealing material may contain only one type of liquid epoxy compound, or two or more types. However, the total amount of the liquid epoxy compounds is preferably 60 mass% or less, more preferably 50 mass% or less, of the total amount of the sheet-like sealing material.

[0062] Furthermore, the sheet-shaped sealing material may contain a resin component that does not have an epoxy group (hereinafter also referred to as a "non-epoxy resin"), provided that the object and effect of the present invention are not impaired. The sheet-shaped sealing material may contain only one type of non-epoxy resin, or may contain two or more types. Examples of non-epoxy resins include styrene-based resins (including polystyrene and styrene-butadiene-styrene block copolymers), polyamide, polyamideimide, polyurethane, polybutadiene, polychloroprene, polyether, polyester, phenol, terpene, xylene resin, ketone resin, cellulose resin, fluorine-based oligomer, silicon-based oligomer, polysulfide-based oligomer, etc. Among the above non-epoxy resins, styrene-based resins are preferred from the viewpoints of compatibility with solid epoxy, transparency, and performance retention.

[0063] When the sheet-shaped sealing material contains a non-epoxy resin, the total amount of the non-epoxy resin is preferably 3% by mass to 60% by mass, more preferably 5% by mass to 30% by mass, based on the total amount of the sheet-shaped sealing material. When the amount of the non-epoxy resin is within this range, it is easy to adjust the viscosity and adhesiveness of the resin without impairing the performance of the epoxy resin.

[0064] (G) Various additives The sheet-like sealing material may further contain fillers, modifiers, stabilizers, etc., within the scope that does not impair the objects and effects of the present invention. Specific examples of fillers include glass beads, styrene-based polymer particles, methacrylate-based polymer particles, ethylene-based polymer particles, propylene-based polymer particles, etc. The sheet-like sealing material may contain only one type of filler, or may contain two or more types of fillers.

[0065] Specific examples of the modifier include a polymerization initiator, an antioxidant, a leveling agent, a wettability improver, a surfactant, a plasticizer, a solvent, a silane coupling agent, etc. The sheet-like sealing material may contain only one type of these modifiers, or may contain two or more types.

[0066] On the other hand, specific examples of stabilizers include ultraviolet absorbers, preservatives, antibacterial agents, etc. The sheet-shaped sealing material may contain only one of these, or may contain two or more of them.

[0067] However, the total amount of the various additives is preferably 50% by mass or less based on the total amount of the sheet-shaped sealing material.

[0068] (H) Manufacturing method of sheet-shaped sealing material The sheet-like sealing material is prepared by preparing a resin composition containing the above-mentioned (A) alicyclic epoxy compound, (B) solid epoxy compound, (C) photocationic polymerization initiator, and (D) photocuring retarder, as well as (E) photosensitizer, (F) other resins, and (G) various additives as needed, and dissolving this in a solvent to form a varnish.

[0069] Examples of the solvent include aromatic solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethers such as ether, dibutyl ether, tetrahydrofuran, dioxane, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, propylene glycol or dialkyl ether; aprotic polar solvents such as N-methylpyrrolidone, dimethylimidazolidinone and dimethylformaldehyde; and esters such as ethyl acetate and butyl acetate.

[0070] When preparing the varnish, the components may be mixed at once, or the (A) alicyclic epoxy compound and / or the (B) solid epoxy compound may be dissolved in a solvent, and then the other components may be mixed in. Examples of methods for mixing the components include known stirring methods.

[0071] Next, the varnish is applied onto a separator, and the solvent is removed. The method for applying the varnish is not particularly limited, and examples include screen printing, dispenser application, various roll methods, etc. The thickness of the applied varnish is appropriately selected depending on the desired film thickness of the sheet-like sealing material. The drying temperature and drying time of the varnish are appropriately selected depending on the type and amount of solvent. The drying temperature is preferably 20 to 100°C, and the drying time is preferably about 1 minute to 3 hours. The drying method is not particularly limited, and examples include hot air drying and vacuum drying. In this way, the above-mentioned sheet-like sealing material is obtained.

[0072] Here, if necessary, another separator may be further disposed on the side of the sheet-shaped sealing material opposite to the surface laminated with the separator, and the sheet-shaped sealing material may be sandwiched between the two separators. This prevents contamination of the sheet-shaped sealing material, and allows, for example, storage for a certain period of time. The type of separator is not particularly limited and may be the same as that of known separators for sheet-shaped sealing materials. The separator is preferably a film having moisture barrier properties or gas barrier properties, such as a polyethylene terephthalate film. The thickness of the separator depends on the material, but may be, for example, 20 μm or more and 100 μm or less. Furthermore, the separator may or may not be optically transparent.

[0073] (I) Physical properties of sheet-type sealing material The thickness of the sheet-like sealing material is appropriately selected depending on the application of the sheet-like sealing material, but when the sheet-like sealing material is used as an interlayer adhesive for a display device, for example, as an interlayer adhesive on the back side of a display device, the thickness is preferably 5 μm or more and 50 μm or less, and more preferably 7 μm or more and 40 μm or less. When the thickness of the sheet-like sealing material is 5 μm or more, the cured product of the sheet-like sealing material can easily absorb and relieve stress applied to various components. On the other hand, when the thickness of the sheet-like sealing material is 50 μm or less, it becomes easier to reduce the thickness and weight of the display device.

[0074] In addition, the sheet-shaped sealing material was exposed to light with a wavelength of 365 nm at an illuminance of 100 mW / cm 2 The resin is irradiated with UV light for 10 to 60 seconds, left to stand for 10 to 60 minutes, and then bonded to various components (e.g., substrates). During bonding, it is preferable that the resin can be fixed to a degree that prevents peeling or misalignment, and it is necessary that the curing reaction does not proceed excessively after UV irradiation (at the time of bonding). On the other hand, if the curing reaction is insufficient after UV irradiation, the resin may become too fluid, which may cause the resin to overflow from the edge of the substrate during bonding.

[0075] Adhesion strength is an index used to determine the state of curing after UV irradiation. The adhesive strength is preferably 1 N / 25 mm or more and 40 N / 25 mm or less, and more preferably 3 N / 25 mm or more and 30 N / 25 mm or less (provided that the resin does not protrude from the edges of various components (e.g., substrates)). When the adhesive strength is within this range, the sheet-shaped sealing material can be kept in close contact with various components for a certain period of time even after light irradiation. Therefore, after light irradiation of the sheet-shaped sealing material, the sheet-shaped sealing material and various components can be overlapped and reliably bonded. The adhesive strength is measured as follows: Immediately after UV irradiation, one side of the sheet-shaped sealing material is bonded to alkali-free glass, and the other side is bonded to an aluminum-deposited PET film. Then, with the glass substrate fixed vertically, the aluminum-deposited PET film is peeled vertically at a peeling speed of 30 mm. The adhesive strength between the sheet-shaped sealing material and the alkali-free glass at this time is defined as the adhesive strength.

[0076] On the other hand, the sheet-shaped sealing material was irradiated with light of wavelength 365 nm at an illuminance of 100 mW / cm 2 When the sheet-like sealing material is irradiated with UV light for 40 seconds and then heated at 100°C for 15 minutes, the adhesive strength to alkali-free glass is preferably 3 N / 25 mm or more and 40 N / 25 mm or less, and more preferably 5 N / 25 mm or more and 39 N / 25 mm or less. When the adhesive strength is within this range, it can be said that the sheet-like sealing material has good curing properties after light irradiation and heating. Therefore, sufficient curing is possible in a relatively short time and at a low temperature. The adhesive strength is also measured in the same manner as above, after UV irradiation, by laminating the sheet-like sealing material with alkali-free glass and aluminum-deposited PET, heating, and then measuring the adhesive strength in the same manner as above.

[0077] (J) Uses and methods of use of sheet-type sealing material The sheet-like sealing material described above can be used as an interlayer adhesive for bonding two components in various display devices, and is particularly suitable for bonding a display element of a display device to a metal plate or resin film arranged on its back side.

[0078] The method for laminating two members (hereinafter also referred to as the "first member" and the "second member") using the sheet-like sealing material is described below. However, the method for using the sheet-like sealing material is not limited to the following method. First, light is irradiated onto the sheet-like sealing material. If the sheet-like sealing material is sandwiched between two separators, it is preferable to peel off the separator on one side and irradiate with light. The wavelength of the irradiated light is appropriately selected depending on the type of (C) photocationic polymerization initiator and (E) photosensitizer in the sheet-like sealing material, but is preferably 355 nm or more and 405 nm or less, and more preferably 365 nm or more and 395 nm or less. The illuminance of the light at this time is 10 mW / cm. 2 More than 1000mW / cm 2 Less than 50mW / cm is preferable. 2 More than 500mW / cm 2The irradiation time is preferably 3 seconds or more and 120 seconds or less, and more preferably 10 seconds or more and 60 seconds or less. When the light illuminance and irradiation time are within the above ranges, the sheet-shaped sealing material does not harden excessively, and can maintain a state in which it easily adheres to the first member and the second member.

[0079] After the light irradiation, a first member is adhered to one side of the sheet-shaped sealing material. Furthermore, a second member is adhered to the other side of the sheet-shaped sealing material. The time from the light irradiation to the adhesion of the sheet-shaped sealing material to the first and second members is preferably within 60 minutes, more preferably within 30 minutes. If it is within 60 minutes, the photocuring of the sheet-shaped sealing material does not proceed excessively, and the sheet-shaped sealing material can be adhered very well to the first and second members. Furthermore, the adhesion of the sheet-shaped sealing material to the first and second members is preferably carried out in an environment of -20°C or higher and 50°C or lower, for example, room temperature (25°C).

[0080] The laminate of the first member, sheet-like sealing material, and second member is then heated to cure the sheet-like sealing material. The heating temperature is preferably 50°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. The heating time is preferably 3 minutes or higher and 3 hours or lower, and more preferably 5 minutes or higher and 2 hours or lower. By using this heating temperature and heating time, the first member and the second member can be firmly bonded together without deterioration. [Example]

[0081] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0082] [material] In the examples and comparative examples, the following materials were used.

[0083] (A) Alicyclic epoxy compound CEL2021P: A compound represented by the following formula (CEL2021P, manufactured by Daicel Corporation, viscosity of 220 to 270 mPa s when measured with a Brookfield viscometer at 25°C) [ka]

[0084] (B) Solid epoxy compound jER-4005P: Bisphenol F epoxy resin (jER-4005P, manufactured by Mitsubishi Chemical Corporation, weight-average molecular weight (Mw) 2000) EXA-4850-150: Bisphenol A epoxy resin (EPICRON EXA-4850-150, manufactured by DIC Corporation, weight-average molecular weight (Mw) 900) YX6954-B35: Biphenyl-type epoxy resin (YX6954-B35, manufactured by Mitsubishi Chemical Corporation, weight-average molecular weight (Mw) 36,691)

[0085] (C) Photocationic polymerization initiator CPI-210S: Triarylsulfonium salt represented by the following structural formula (manufactured by San-Apro Co., Ltd.) [ka]

[0086] (D) Photocuring retarder Hindered amine (Tinuvin 123, manufactured by BASF)

[0087] (E) Photosensitizer UVS-581: 9,10-bis(octanoyloxy)anthracene (UVS-581, Kawasaki Kasei Chemicals)

[0088] (F) Other resins Styrene resin (FTR8120, Mitsui Chemicals)

[0089] (G) Leveling agent BYK302: Polyether-modified polydimethylsiloxane (BYK302, manufactured by BYK-Chemie) (H) Thermal cationic polymerization initiator CXC-1821: A thermal cationic polymerization initiator represented by the following formula (K-Pure CXC-1821, manufactured by King Industries) [ka]

[0090] [Example 1] In a flask, (A) an alicyclic epoxy compound, (B) a solid epoxy compound, (C) a photocationic polymerization initiator, (D) a photocuring retarder, (F) other resins, (G) a leveling agent, and MEK solvent were mixed in the mass ratios shown in Table 1. The mixture was then stirred and dissolved at room temperature to prepare a varnish.

[0091] The prepared varnish was applied to a separator (PET75-H270, manufactured by Nichiei Shinka Co., Ltd., thickness 75 μm) with an applicator using a coating machine so that the thickness after drying would be approximately 20 μm. The coating film was dried in an inert oven at 80°C for 3 minutes. This dried and removed the methyl ethyl ketone (MEK) in the varnish, and a sheet-like sealing material was obtained.

[0092] [Example 2 and Comparative Examples 1 to 3] A laminate was obtained in the same manner as in Example 1, except that the amounts of each component used in preparing the varnish were changed as shown in Table 1.

[0093] [evaluation] The sheet-like sealing materials produced in the examples and comparative examples were evaluated by the following methods. The results are shown in Table 1.

[0094] (1) Bonding ability of sheet sealant immediately after UV irradiation The sheet-shaped sealing material is irradiated with light of 369 nm wavelength at an illuminance of 100 mW / cm using a UV irradiator (for example, a water-cooled UV-LED Solidcure 2 HD manufactured by Integration Technology Co., Ltd.). 2The sheet-like sealing material was irradiated with light for 40 seconds. Immediately after that, the sheet-like sealing material was attached to non-alkali glass, and an aluminum-deposited PET film was attached to the sheet-like sealing material on the side opposite the glass. The non-alkali glass was then fixed vertically to a jig on a universal testing machine (2200X manufactured by Intesco), and the aluminum-deposited PET film was peeled off vertically at a peeling rate of 30 mm / min to measure the adhesive strength (peel strength) between the sheet-like sealing material and the non-alkali glass. The lamination property was evaluated according to the following criteria. 〇: 3N / 25mm or more, 30N / 25mm or less ×: Less than 3N / 25mm, or more than 30N / 25mm, or resin protruding from the edge

[0095] (2) Adhesion of sheet sealant after 30 minutes of UV irradiation The sheet-shaped sealing material was irradiated with light of 365 nm wavelength at an illuminance of 100 mW / cm by a UV irradiation device. 2 The sheet-shaped sealing material was irradiated with UV light for 40 seconds. After the irradiation, the sheet-shaped sealing material was left to stand for 30 minutes. After that, the lamination property was evaluated in the same manner as in (1) Lamination property of the sheet-shaped sealing material immediately after UV irradiation. The evaluation was based on the following criteria. 〇:3N / 25mm or more and 30N / mm or less ×: Less than 3N / 25mm, or more than 30N / 25mm, or resin protruding from the edge

[0096] (3) Heat curing properties of sheet sealant after UV irradiation The sheet-shaped sealing material was irradiated with light of 365 nm wavelength at an illuminance of 100 mW / cm by a UV irradiation device. 2 The sheet-shaped sealing material was then irradiated with UV light for 40 seconds. The sheet-shaped sealing material was then attached to alkali-free glass, and an aluminum-deposited PET film was attached to the sheet-shaped sealing material on the side opposite the glass, followed by heating at 100°C for 15 minutes. The sheet-shaped sealing material was then evaluated for its adhesion properties using the same procedure as in (1) the adhesion properties of the sheet-shaped sealing material immediately after UV irradiation. The evaluation was based on the following criteria. 〇: More than 5N / 25mm and less than 40N / mm ×: 5N / 25mm or less, or more than 40N / 25mm

[0097] (4) Storage property A separator was also placed on the other side of the sheet-shaped sealing material prepared in the above Examples and Comparative Examples. The sheet-shaped sealing material was sealed in a light-shielding aluminum bag and placed in an environment of 23°C and 50% humidity for 6 months. Thereafter, the lamination property was confirmed and the storage property was evaluated using the same method as above. The evaluation criteria were the same as those for (3) above, "Thermal curing property of sheet-shaped sealing material after UV irradiation."

[0098] [Table 1]

[0099] As shown in Table 1 above, the compounds of Examples 1 and 2, which combine an alicyclic epoxy compound, a solid epoxy compound, a photocationic polymerization initiator, and a photocuring retarder, were able to be sufficiently cured even when lamination was performed after a certain time had elapsed after UV irradiation (Examples 1 and 2). In other words, after UV irradiation was performed on the sheet-like sealing material alone, the desired components were adhered to both sides of the sheet-like sealing material, respectively, and the sheet-like sealing material was cured by heating. Furthermore, since the sheet-like sealing material had already been cured to some extent by UV irradiation, the subsequent heating time could be shortened, and the heating temperature did not need to be excessively high.

[0100] On the other hand, when a thermal cationic polymerization initiator was used instead of a photo-cationic polymerization initiator, the thermal curing property after UV irradiation was insufficient, and the storage stability was also poor (Comparative Examples 1 and 2). Furthermore, when a photo-cationic polymerization initiator was used without adding a photo-curing retarder, the film cured immediately after UV irradiation, making it impossible to bond the film together (Comparative Example 3). [Industrial Applicability]

[0101] The sheet-like sealing material of the present invention can bond components together at low temperatures in a short time, and can therefore be used as an interlayer adhesive for bonding various components of various display devices.

Claims

1. an alicyclic epoxy compound; an epoxy compound that is solid at 25°C; a photocationic polymerization initiator; a photocure retarder; A sheet-like sealing material comprising:

2. The photocure retarder is a hindered amine. The sheet-like sealing material according to claim 1 .

3. further comprising a photosensitizer, The sheet-like sealing material according to claim 1 .

4. The thickness is 5 μm or more and 50 μm or less. The sheet-like sealing material according to claim 1 .

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