Sealant for organic EL display elements

Abstract

The purpose of the present invention is to provide a sealant for an organic EL display element, said sealant having excellent adhesiveness and capable of being sufficiently cured even when disposed in a light-blocking part. The present invention provides a sealant for an organic EL display element, said sealant containing a curable resin, a photocationic polymerization initiator, a thermal cationic polymerization initiator, and a filler, wherein the curable resin contains an alicyclic epoxy compound and an epoxy compound having a flexible skeleton.

Description

[Technical Field]

[0001] The present invention relates to a sealant for an organic EL display element that has excellent adhesiveness and can be cured sufficiently even when placed in a light-shielding portion. [Background technology]

[0002] An organic electroluminescent display element (organic EL display element) has a thin film structure in which an organic light-emitting material layer is sandwiched between a pair of opposing electrodes. Electrons are injected into this organic light-emitting material layer from one electrode, and holes are injected from the other electrode, causing the electrons and holes to combine within the organic light-emitting material layer, resulting in self-luminescence. Compared to liquid crystal display elements and other elements that require a backlight, organic EL display elements have the advantages of better visibility, thinner designs, and the ability to be driven by a low DC voltage.

[0003] However, such organic EL display elements have a problem in that when the organic light-emitting material layer or electrodes are exposed to the outside air, their light-emitting characteristics rapidly deteriorate, shortening their lifespan. Therefore, in order to improve the stability and durability of organic EL display elements, sealing technology that isolates the organic light-emitting material layer and electrodes from moisture and oxygen in the air is essential.

[0004] Patent Document 1 discloses a method for sealing an organic EL display element by using a structure including an organic filling layer that covers and seals a laminate having an organic light-emitting material layer, and a moisture-absorbing sealing layer (sealing wall) that covers the side surface of the organic filling layer. Typically, as a sealant for an organic EL display element, an in-plane sealant is used for the organic filling layer, and a peripheral sealant having a different component from the in-plane sealant is used for the sealing wall. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-67598 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a sealant for an organic EL display element that has excellent adhesiveness and can be cured sufficiently even when placed in a light-shielding portion. [Means for solving the problem]

[0007] The present invention provides a sealant for an organic electroluminescent display element, which contains a curable resin, a photocationic polymerization initiator, a thermal cationic polymerization initiator, and a filler, wherein the curable resin contains an alicyclic epoxy compound and an epoxy compound having a flexible skeleton. The present invention will be described in detail below.

[0008] In recent years, the display frame of an organic EL display element has become increasingly narrow. This has led to the placement of a sealant for an organic EL display element directly under an electrode, etc., which can block the light irradiated during photocuring of the sealant, preventing it from reaching the interior of the sealant and resulting in insufficient curing. The present inventors have investigated the use of a photocationic polymerization initiator for photocuring a cationic polymerizable compound in a sealant for an organic EL display element, as well as a thermal cationic polymerization initiator for thermally curing the insufficiently photocured portion. However, when thermally curing is performed using a thermal cationic polymerization initiator, the resulting sealant may have poor adhesion or may even exhibit reduced curing properties in the light-shielding portion. Therefore, the present inventors have investigated the use of a combination of an alicyclic epoxy compound and an epoxy compound having a flexible backbone as a curable resin in a sealant for an organic EL display element containing a photocationic polymerization initiator and a thermal cationic polymerization initiator. As a result, they have discovered that a sealant for an organic EL display element having excellent adhesion and capable of sufficient curing even when placed in a light-shielding portion can be obtained, thereby completing the present invention.

[0009] The sealant for an organic EL display element of the present invention contains a curable resin. The curable resin contains an alicyclic epoxy compound and an epoxy compound having a flexible skeleton. By containing a photocationic polymerization initiator described later and a thermal cationic polymerization initiator described later, and further containing the alicyclic epoxy compound and the epoxy compound having a flexible skeleton as the curable resin, the sealant for an organic EL display element of the present invention has excellent adhesion and can be sufficiently cured even when placed in a light-shielding portion.

[0010] Examples of the alicyclic epoxy compound include 3',4'-epoxycyclohexylmethyl (3,4-epoxy)cyclohexane carboxylate, 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, 3',4'-epoxycyclohexylmethyl (meth)acrylate, 1,2:8,9-diepoxylimonene, 4-vinylcyclohexene dioxide, vinylcyclohexene dioxide, methylated vinylcyclohexene dioxide, bis(3,4-epoxycyclohexylmethyl)ether, 3,4,3',4'-diepoxybicyclohexyl, bis(3,4-epoxycyclohexyl)adipate, bis(2,3-epoxycyclopentyl)ether, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, and dicyclopentadiene dioxide. Of these, 3',4'-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate is preferred.

[0011] Examples of the flexible skeleton in the epoxy compound having a flexible skeleton include a lactone ring-opening structure, a polyalkylene oxide structure, a rubber structure derived from a conjugated diene, a polysiloxane structure, etc. Among these, at least one structure selected from the group consisting of a lactone ring-opening structure, a polyalkylene oxide structure, a rubber structure derived from a conjugated diene, and a polysiloxane structure is preferred, and a polyalkylene oxide structure is more preferred.

[0012] Specifically, the epoxy compound having a flexible skeleton is preferably a compound represented by the following formula (1).

[0013] [ka]

[0014] In formula (1), X represents an ethyleneoxyethyl group, a di(ethyleneoxy)ethyl group, a tri(ethyleneoxy)ethyl group, a tetra(ethyleneoxy)ethyl group, a propyleneoxypropyl group, a di(propyleneoxy)propyl group, a tri(propyleneoxy)propyl group, a tetra(propyleneoxy)propyl group, a butyleneoxybutyl group, a di(butyleneoxy)butyl group, a tri(butyleneoxy)butyl group, a tetra(butyleneoxy)butyl group, or an alkylene group having from 2 to 15 carbon atoms; and n is 1 to 10.

[0015] Among the compounds represented by the above formula (1), commercially available examples include EPICLON EXA-4850-150 and EPICLON EXA-4850-1000 (both manufactured by DIC Corporation).

[0016] The ratio of the alicyclic epoxy compound to the epoxy compound having a flexible skeleton (alicyclic epoxy compound:epoxy compound having a flexible skeleton) is preferably 2:1 to 1:3 by weight. When the ratio of the alicyclic epoxy compound to the epoxy compound having a flexible skeleton is within this range, the resulting sealant for an organic EL display element has superior adhesiveness and curing properties in the light-shielding portion. The ratio of the alicyclic epoxy compound to the epoxy compound having a flexible skeleton (alicyclic epoxy compound:epoxy compound having a flexible skeleton) is more preferably 1:1 to 1:2 by weight.

[0017] The curable resin may contain other curable resins in addition to the alicyclic epoxy compound and the epoxy compound having a flexible skeleton. When the other curable resin is contained, the preferred lower limit of the total content of the alicyclic epoxy compound and the epoxy compound having a flexible skeleton per 100 parts by weight of the curable resin is 60 parts by weight. When the total content of the alicyclic epoxy compound and the epoxy compound having a flexible skeleton is 60 parts by weight or more, the resulting sealant for an organic EL display element has better adhesion and light-shielding portion curability. A more preferred lower limit of the total content of the alicyclic epoxy compound and the epoxy compound having a flexible skeleton is 70 parts by weight.

[0018] Examples of the other curable resins include epoxy compounds other than the alicyclic epoxy compounds and the epoxy compounds having a flexible skeleton, oxetane compounds, (meth)acrylic compounds, and urethane compounds. In this specification, the term "(meth)acrylic" means acrylic or methacrylic, the term "(meth)acrylic compound" means a compound having a (meth)acryloyl group, and the term "(meth)acryloyl" means acryloyl or methacryloyl.

[0019] Examples of the other epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, diethylene glycol diglycidyl ether, polyethylene glycol glycidyl ether, polytetramethylene glycol glycidyl ether, 2-(2-butyl)phenyl glycidyl ether, neopentyl glycol diglycidyl ether, O-phenylphenol glycidyl ether, 1,7-octadiene diepoxide, hydrogenated bisphenol A type epoxy resins, hydrogenated bisphenol F type epoxy resins, dicyclopentadiene type epoxy compounds, phenol novolac type epoxy compounds, and cresol novolac type epoxy compounds.

[0020] Examples of the oxetane compound include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, di[2-(3-oxetanyl)butyl]ether, and 3-ethyl-3-hydroxymethyloxetane.

[0021] Examples of the (meth)acrylic compound include resorcinol-type epoxy (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, methylcyclohexyl (meth)acrylate, norbornylmethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, cyclodecyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and 2-hydroxybutyl (meth)acrylate. In this specification, the term "(meth)acrylate" refers to acrylate or methacrylate, and the term "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have been reacted with (meth)acrylic acid.

[0022] Examples of the urethane compound include a reaction product of an isocyanate compound and an arbitrary polyol compound. Examples of the isocyanate compound include a toluene diisocyanate compound and a diphenylmethane diisocyanate compound. Examples of the toluene diisocyanate compound include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate, and mixtures thereof. Examples of the diphenylmethane diisocyanate compound include 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and mixtures thereof.

[0023] The sealant for an organic EL display element of the present invention contains a photocationic polymerization initiator and a thermal cationic polymerization initiator. By using the above-mentioned photocationic polymerization initiator and the above-mentioned thermal cationic polymerization initiator in combination, the sealant for an organic EL display element of the present invention can be sufficiently cured even when placed in a light-shielding portion.

[0024] The photocationic polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid upon irradiation with light, and may be either an ionic photoacid generating type or a nonionic photoacid generating type.

[0025] The anion moiety of the ionic photoacid generating cationic photopolymerization initiator is, for example, BF4 - , PF6 - , SbF6 - , or (BX4) - (wherein X represents a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups), etc. Examples of the ionic photoacid-generating photocationic polymerization initiator include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, and (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salts, each of which has the anion moiety.

[0026] Examples of the aromatic sulfonium salt include bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(diphenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(diphenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, diphenyl-4-(phenylthio)phenylsulfonium tetrakis(pentafluorophenyl)borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate,

[0033] Examples of sulfonium tetrakis(pentafluorophenyl)borate include triarylsulfonium tetrakis(pentafluorophenyl)borate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, and tris(4-(4-acetylphenyl)thiophenyl)sulfonium tetrakis(pentafluorophenyl)borate.

[0027] Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluorophosphate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluoroantimonate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrafluoroborate, and 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrakis(pentafluorophenyl)borate.

[0028] Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis(pentafluorophenyl)borate.

[0029] Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2-cyanopyridinium tetrakis(pentafluorophenyl)borate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluorophosphate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluoroantimonate, 1-(naphthylmethyl)-2-cyanopyridinium tetrafluoroborate, and 1-(naphthylmethyl)-2-cyanopyridinium tetrakis(pentafluorophenyl)borate.

[0030] Examples of the (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salt include (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluorophosphate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluoroantimonate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrafluoroborate, and (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrakis(pentafluorophenyl)borate.

[0031] Examples of the nonionic photoacid-generating cationic photopolymerization initiator include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenolsulfonic acid esters, diazonaphthoquinone, and N-hydroxyimide sulfonates.

[0032] Among these, from the viewpoint of the strength of the acid generated, the cationic photopolymerization initiator is preferably a salt whose counter anion is tetrakis(pentafluorophenyl)borate.

[0033] Among the above-mentioned cationic photopolymerization initiators, commercially available ones include, for example, cationic photopolymerization initiators manufactured by Midori Chemical Industry Co., Ltd., cationic photopolymerization initiators manufactured by Union Carbide Corporation, cationic photopolymerization initiators manufactured by ADEKA Corporation, cationic photopolymerization initiators manufactured by 3M Corporation, cationic photopolymerization initiators manufactured by BASF Corporation, and cationic photopolymerization initiators manufactured by Rhodia Corporation. Examples of the cationic photopolymerization initiators manufactured by Midori Chemical Co., Ltd. include DTS-200. Examples of the cationic photopolymerization initiators manufactured by Union Carbide include UVI6990 and UVI6974. Examples of the cationic photopolymerization initiators manufactured by ADEKA Corporation include SP-150 and SP-170. Examples of the cationic photopolymerization initiator manufactured by 3M include FC-508 and FC-512. Examples of the cationic photopolymerization initiators manufactured by BASF include IRGACURE261 and IRGACURE290. Examples of the cationic photopolymerization initiators manufactured by Rhodia include PI2074.

[0034] The content of the cationic photopolymerization initiator is preferably 0.1 parts by weight at the lower limit and 2.5 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (when a polyolefin described below is contained, the total of the curable resin and the polyolefin described below). When the content of the cationic photopolymerization initiator is 0.1 parts by weight or more, the resulting sealant for organic EL display elements has superior photocurability. When the content of the cationic photopolymerization initiator is 2.5 parts by weight or less, the curing reaction of the resulting sealant for organic EL display elements does not become too fast, and stable adhesion can be obtained. The lower limit of the content of the cationic photopolymerization initiator is more preferably 0.5 parts by weight, and the upper limit is more preferably 1.5 parts by weight.

[0035] The thermal cationic polymerization initiator has an anion moiety of BF4 - , PF6 - , SbF6 - , or (BX4) - (wherein X represents a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups), sulfonium salts, phosphonium salts, ammonium salts, etc. are preferred. Of these, sulfonium salts and ammonium salts are preferred.

[0036] Examples of the sulfonium salt include benzyl(4-hydroxyphenyl)methylsulfonium tris(pentafluoroethyl)trifluorophosphate, triphenylsulfonium tetrafluoroborate, and triphenylsulfonium hexafluoroantimonate.

[0037] Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantimonate and tetrabutylphosphonium hexafluoroantimonate.

[0038] Examples of the ammonium salts include dimethylphenyl(4-methoxybenzyl)ammonium hexafluorophosphate, dimethylphenyl(4-methoxybenzyl)ammonium hexafluoroantimonate, dimethylphenyl(4-methoxybenzyl)ammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(4-methylbenzyl)ammonium hexafluorophosphate, dimethylphenyl(4-methylbenzyl)ammonium hexafluoroantimonate, dimethylphenyl(4-methylbenzyl)ammonium hexafluorotetrakis(pentafluorophenyl)borate, and methylphenyldibenzylammonium hexafluorophosphate. , methylphenyldibenzylammonium hexafluoroantimonate, methylphenyldibenzylammonium tetrakis(pentafluorophenyl)borate, phenyltribenzylammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(3,4-dimethylbenzyl)ammonium tetrakis(pentafluorophenyl)borate, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-diethyl-N-benzylanilinium tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N,N-diethyl-N-benzylpyridinium trifluoromethanesulfonate, and the like.

[0039] Among these, from the viewpoint of the strength of the acid generated, the thermal cationic polymerization initiator is preferably a salt whose counter anion is tetrakis(pentafluorophenyl)borate.

[0040] Among the above-mentioned thermal cationic polymerization initiators, commercially available ones include, for example, a thermal cationic polymerization initiator manufactured by Sanshin Chemical Industry Co., Ltd., a thermal cationic polymerization initiator manufactured by King Industries, and a thermal cationic polymerization initiator manufactured by San-Apro Co., Ltd. Examples of the thermal cationic polymerization initiators manufactured by Sanshin Chemical Industry Co., Ltd. include San-Aid SI-60, San-Aid SI-80, San-Aid SI-B3, San-Aid SI-B3A, and San-Aid SI-B4. Examples of the thermal cationic polymerization initiators manufactured by King Industries include CXC-1612 and CXC-1821. Examples of the thermal cationic polymerization initiators manufactured by San-Apro include TA-100 and TA-100FG.

[0041] The content of the thermal cationic polymerization initiator is preferably 0.5 parts by weight at the lower limit and 3.0 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (or, when a polyolefin described below is contained, the total of the curable resin and the polyolefin described below). When the content of the thermal cationic polymerization initiator is 0.5 parts by weight or more, the resulting sealant for organic EL display elements has superior thermosetting properties. When the content of the thermal cationic polymerization initiator is 3.0 parts by weight or less, the curing reaction of the resulting sealant for organic EL display elements does not become too fast, resulting in superior workability and a more uniform cured product. The lower limit of the content of the thermal cationic polymerization initiator is more preferably 1.0 parts by weight, and the upper limit is more preferably 2.0 parts by weight.

[0042] The sealant for an organic EL display element of the present invention may contain a radical polymerization initiator. Examples of the radical polymerization initiator include a photoradical polymerization initiator and a thermal radical polymerization initiator.

[0043] Examples of the photoradical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, and thioxanthone compounds. Specific examples of the photoradical polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 1,2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4-(4-morpholinyl)phenyl)-1-butanone, 2,2-dimethoxy-2-phenylacetophenone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl- Examples include 1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 1-(4-(2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-(phenylthio)phenyl)-1,2-octanedione 2-(O-benzoyloxime), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether.

[0044] Examples of the thermal radical polymerization initiator include azo compounds, organic peroxides, and the like. Examples of the azo compound include 2,2'-azobis(2,4-dimethylvaleronitrile) and azobisisobutyronitrile. Examples of the organic peroxide include benzoyl peroxide, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, and peroxydicarbonate.

[0045] Among the above thermal radical polymerization initiators, commercially available ones include, for example, VPE-0201, VPE-0401, VPE-0601, VPS-0501, VPS-1001, and V-501 (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0046] The content of the radical polymerization initiator is preferably 0.05 parts by weight at the lower limit and 5 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (when a polyolefin described below is contained, the total of the curable resin and the polyolefin described below). When the content of the radical polymerization initiator is 0.05 parts by weight or more, the resulting sealant for organic EL display elements has superior curability. When the content of the radical polymerization initiator is 5 parts by weight or less, the curing reaction of the resulting sealant for organic EL display elements does not become too fast, resulting in superior workability and a more uniform cured product. A more preferred lower limit of the content of the radical polymerization initiator is 0.5 parts by weight, and a more preferred upper limit is 2 parts by weight.

[0047] The sealant for an organic EL display element of the present invention may contain a sensitizer. The sensitizer has the role of further improving the polymerization initiation efficiency of the polymerization initiator and further accelerating the curing reaction of the sealant for an organic EL display element of the present invention.

[0048] Examples of the sensitizer include anthracene compounds, thioxanthone compounds, 2,2-dimethoxy-1,2-diphenylethan-1-one, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide. Examples of the anthracene compounds include 9,10-dibutoxyanthracene. Examples of the thioxanthone compounds include 2,4-diethylthioxanthone. These sensitizers may be used alone or in combination of two or more.

[0049] The content of the sensitizer is preferably 0.05 parts by weight at the lower limit and 3 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (when a polyolefin described below is contained, the total of the curable resin and the polyolefin described below). When the content of the sensitizer is 0.05 parts by weight or more, the sensitizing effect is more pronounced. When the content of the sensitizer is 3 parts by weight or less, light can be transmitted to deep areas without excessive absorption. A more preferred lower limit of the content of the sensitizer is 0.1 parts by weight, and a more preferred upper limit is 1 part by weight.

[0050] The sealant for an organic EL display element of the present invention may contain a heat curing agent. Examples of the heat curing agent include hydrazide compounds, imidazole derivatives, acid anhydrides, dicyandiamide, guanidine derivatives, modified aliphatic polyamines, and addition products of various amines and epoxy resins.

[0051] Examples of the hydrazide compound include 1,3-bis(hydrazinocarboethyl)-5-isopropylhydantoin, sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, and malonic acid dihydrazide. Examples of the imidazole derivatives include 1-cyanoethyl-2-phenylimidazole, N-(2-(2-methyl-1-imidazolyl)ethyl)urea, 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine, N,N'-bis(2-methyl-1-imidazolylethyl)urea, N,N'-(2-methyl-1-imidazolylethyl)-adipamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2-phenyl-4,5-dihydroxymethylimidazole. Examples of the acid anhydride include tetrahydrophthalic anhydride and ethylene glycol bis(anhydrotrimellitate). These heat curing agents may be used alone or in combination of two or more.

[0052] Among the above-mentioned heat curing agents, commercially available ones include, for example, SDH (manufactured by Nippon Finechem Co., Ltd.), ADH (manufactured by Otsuka Chemical Co., Ltd.), Amicure VDH, Amicure VDH-J, and Amicure UDH (all manufactured by Ajinomoto Fine-Techno Co., Ltd.).

[0053] The content of the thermosetting agent is preferably 0.01 parts by weight at the lower limit and 10 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (when a polyolefin described below is contained, the total of the curable resin and the polyolefin described below). When the content of the thermosetting agent is 0.01 parts by weight or more, the resulting sealant for an organic EL display element has better thermosetting properties. When the content of the thermosetting agent is 10 parts by weight or less, the resulting sealant for an organic EL display element has better storage stability. The lower limit of the content of the thermosetting agent is more preferably 0.5 parts by weight, and the upper limit is more preferably 5 parts by weight, and even more preferably 1 part by weight, and even more preferably 3 parts by weight.

[0054] The sealant for an organic EL display element of the present invention contains a filler. As the filler, an inorganic filler or an organic filler can be used. Examples of the inorganic filler include silica, talc, and alumina. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and acrylic polymer fine particles. Among these, talc is preferred as the filler.

[0055] The sealant for an organic EL display element of the present invention may contain a water-absorbing filler as the filler. By containing the water-absorbing filler, the sealant for an organic EL display element of the present invention has excellent moisture permeation prevention properties.

[0056] Examples of the water-absorbing filler include alkaline earth metal oxides, magnesium oxide, and molecular sieves. Examples of the alkaline earth metal oxides include calcium oxide, strontium oxide, and barium oxide. Among these, from the viewpoint of water absorption, alkaline earth metal oxides are preferred, and calcium oxide is more preferred. These water-absorbing fillers may be used alone or in combination of two or more.

[0057] The filler has an average particle size of preferably 0.5 μm (lower limit) and 10 μm (upper limit). When the filler has an average particle size within this range, the resulting sealant for an organic EL display device has better coatability, adhesiveness, and moisture-proofing properties. The filler's average particle size is more preferably 1.0 μm (lower limit) and 5.0 μm (upper limit). The average particle size of the filler can be measured by dispersing the filler in a solvent (water, organic solvent, etc.) using a particle size distribution measuring device such as NICOMP 380ZLS (manufactured by PARTICLE SIZING SYSTEMS).

[0058] The content of the filler is preferably 10 parts by weight at the lower limit and 50 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (when a polyolefin described below is contained, the total of the curable resin and the polyolefin described below). When the content of the filler is within this range, the resulting sealant for an organic EL display element has better coatability, adhesiveness, and moisture-proofing properties. The lower limit of the content of the filler is more preferably 20 parts by weight, and the upper limit is more preferably 30 parts by weight.

[0059] The sealant for an organic EL display element of the present invention preferably contains a polyolefin. By containing the polyolefin, the sealant for an organic EL display element of the present invention has better moisture permeation prevention properties.

[0060] From the viewpoint of further improving moisture permeation prevention properties, the polyolefin preferably contains at least one selected from the group consisting of polyisobutylene, polybutene, and polybutadiene, and more preferably contains polyisobutylene. The above polyolefins may be used alone or in combination of two or more kinds.

[0061] The weight-average molecular weight of the polyolefin preferably has a lower limit of 10,000 and an upper limit of 400,000. When the weight-average molecular weight of the polyolefin is within this range, the resulting sealant for an organic EL display device has better coatability, adhesiveness, and moisture-proofing properties. The weight-average molecular weight of the polyolefin more preferably has a lower limit of 20,000 and an upper limit of 70,000. In this specification, the "weight average molecular weight" is a value determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted into polystyrene. Examples of columns used in measuring the weight average molecular weight converted into polystyrene by GPC include Shodex LF-804 (manufactured by Showa Denko KK).

[0062] The preferred lower limit of the polyolefin content per 100 parts by weight of the total of the curable resin and the polyolefin is 10 parts by weight, and the preferred upper limit is 80 parts by weight. When the polyolefin content is 10 parts by weight or more, the resulting sealant for organic EL display elements has better moisture permeation prevention properties. When the polyolefin content is 80 parts by weight or less, the resulting sealant for organic EL display elements has better coatability and adhesiveness. The more preferred lower limit of the polyolefin content is 20 parts by weight, and the more preferred upper limit is 60 parts by weight.

[0063] The sealant for an organic EL display element of the present invention may contain a tackifier resin for the purpose of further improving adhesiveness. Examples of the tackifying resin include terpene resins, modified terpene resins, coumarone resins, indene resins, and petroleum resins. Examples of the modified terpene resin include hydrogenated terpene resin, terpene-phenol copolymer resin, and aromatic modified terpene resin. Examples of the petroleum resin include aliphatic petroleum resins, hydrogenated alicyclic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, alicyclic petroleum resins, dicyclopentadiene petroleum resins, and hydrogenated products thereof. Among these, from the viewpoint of the adhesiveness, moisture resistance, compatibility, etc. of the sealant for organic EL display elements, preferred tackifier resins are terpene resins, aromatic-modified terpene resins, terpene-phenol copolymer resins, hydrogenated alicyclic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, and alicyclic petroleum resins, with alicyclic petroleum resins being more preferred, alicyclic saturated hydrocarbon resins and alicyclic unsaturated hydrocarbon resins being even more preferred, and cyclohexyl ring-containing saturated hydrocarbon resins and dicyclopentadiene-modified hydrocarbon resins being particularly preferred. These tackifier resins may be used alone or in combination of two or more.

[0064] The content of the tackifier resin is preferably 0.01 parts by weight at the lower limit and 100 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). By having the content of the tackifier resin within this range, the effect of improving adhesion while maintaining moisture barrier properties can be more effectively exhibited. The more preferred lower limit of the content of the tackifier resin is 0.2 parts by weight, and the more preferred upper limit is 20 parts by weight.

[0065] The sealant for an organic EL display element of the present invention may contain a stabilizer. By containing the stabilizer, the sealant for an organic EL display element of the present invention has better storage stability.

[0066] Examples of the stabilizer include aromatic amine compounds, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and the like. Examples of the aromatic amine compound include benzylamine and aminophenol-type epoxy resin. Of these, aromatic amine compounds are preferred, and benzylamine is more preferred. These stabilizers may be used alone or in combination of two or more.

[0067] The content of the stabilizer is preferably 0.001 parts by weight at the lower limit and 2 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). By using a stabilizer content within this range, the resulting sealant for an organic EL display element has excellent storage stability while maintaining excellent curability. The more preferred lower limit of the stabilizer content is 0.005 parts by weight, and the more preferred upper limit is 1 part by weight.

[0068] The sealant for an organic EL display element of the present invention may contain a silane coupling agent. The silane coupling agent plays a role in improving the adhesion between the sealant for an organic EL display element of the present invention and a substrate or the like.

[0069] Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-isocyanatopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more.

[0070] The content of the silane coupling agent is preferably 0.1 parts by weight at the lower limit and 10 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). By using the silane coupling agent in this range, the bleed-out of excess silane coupling agent can be prevented, while the adhesiveness of the resulting sealant for organic EL display elements can be improved. The lower limit of the content of the silane coupling agent is more preferably 0.5 parts by weight, and the upper limit is more preferably 5 parts by weight.

[0071] The sealant for an organic EL display element of the present invention may contain a surface modifier within a range that does not impair the object of the present invention. By containing the surface modifier, the flatness of the coating film of the sealant for an organic EL display element of the present invention can be improved. Examples of the surface modifier include surfactants and leveling agents.

[0072] Examples of the surface modifier include silicone-based, acrylic-based, and fluorine-based agents. Among the above surface modifiers, commercially available ones include, for example, surface modifiers manufactured by BYK Japan, surface modifiers manufactured by Kusumoto Chemical Co., Ltd., and surface modifiers manufactured by AGC Seimi Chemical Co., Ltd. Examples of the surface modifiers manufactured by BYK Japan include BYK-300, BYK-302, and BYK-331. An example of the surface modifier manufactured by Kusumoto Chemicals Co., Ltd. is UVX-272. An example of the surface modifier manufactured by AGC Seimi Chemical Co., Ltd. is Surflon S-611.

[0073] The sealant for an organic EL display element of the present invention may contain a compound that reacts with the acid generated in the sealant for an organic EL display element and / or an ion exchange resin, as long as the object of the present invention is not impaired.

[0074] Examples of the compound that reacts with the generated acid include substances that neutralize the acid, such as carbonates or bicarbonates of alkali metals, or carbonates or bicarbonates of alkaline earth metals, etc. Specific examples include calcium carbonate, calcium bicarbonate, sodium carbonate, and sodium bicarbonate.

[0075] The ion exchange resin may be of the cation exchange type, anion exchange type, or amphoteric ion exchange type, but the cation exchange type or amphoteric ion exchange type capable of adsorbing chloride ions is particularly preferred.

[0076] The sealant for an organic EL display element of the present invention may contain various known additives, such as a curing retarder, a reinforcing agent, a softener, a plasticizer, a viscosity modifier, an ultraviolet absorber, and an antioxidant, as needed, within the scope of not impairing the object of the present invention.

[0077] The sealant for an organic EL display element of the present invention preferably does not contain a solvent from the viewpoint of further suppressing outgassing. The sealant for an organic EL display element of the present invention can have excellent coatability even without containing a solvent. In this specification, "solvent-free" means that the solvent content is less than 1000 ppm.

[0078] Examples of a method for producing the sealant for an organic EL display element of the present invention include a method of mixing a curable resin, a photocationic polymerization initiator, a thermal cationic polymerization initiator, a filler, and an additive such as a silane coupling agent, which is added as needed, using a mixer. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mixer.

[0079] The cured product of the sealant for organic EL display elements of the present invention is preferably used as a sealing wall surrounding the peripheral portion of an organic EL display element. That is, the sealant for organic EL display elements of the present invention is preferably used as a peripheral sealant for organic EL display elements for forming a sealing wall around a laminate having an organic light-emitting material layer. The peripheral sealant for organic EL display elements is usually used in combination with an in-plane sealant for organic EL display elements that covers the laminate.

[0080] The sealing wall formed using the cured product of the sealant for an organic EL display element of the present invention preferably has a thickness of 5 mm or less, from the viewpoint of ensuring a wide display area of ​​the resulting organic EL display element. [Effects of the Invention]

[0081] According to the present invention, it is possible to provide a sealant for an organic EL display element that has excellent adhesiveness and can be cured sufficiently even when placed in a light-shielding portion. DETAILED DESCRIPTION OF THE INVENTION

[0082] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0083] (Example 1 4、6~ 11 See Example 5 , Comparative Examples 1 to 3) According to the blending ratios shown in Tables 1 and 2, each material was mixed by stirring using a stirring mixer at a stirring speed of 2000 rpm for 3 minutes to obtain the compositions of Examples 1 to 2. 4, 6~11, Refer to Example 5 Thus, sealants for organic EL display elements were produced for Comparative Examples 1 to 3. The stirring mixer used was AR-310 (manufactured by Thinky Corporation).

[0084] <Evaluation> Example Reference example and 、 The sealants for organic EL display elements obtained in the comparative examples were evaluated as follows, and the results are shown in Tables 1 and 2.

[0085] (viscosity) Example Reference example and 、 For each of the sealants for organic EL display elements obtained in the comparative examples, the initial viscosity immediately after production was measured at 25° C. using an E-type viscometer. As the E-type viscometer, a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) was used.

[0086] (Adhesive strength) Example Reference example and 、 To 10 g of each sealant for organic EL displays obtained in the comparative examples, 0.03 g of spacer particles with a diameter of 10 μm was added and uniformly dispersed using a stirrer mixer. Micropearl SP-210 (manufactured by Sekisui Chemical Co., Ltd.) was used as the spacer particles, and ARV-310 (manufactured by Thinky Corporation) was used as the stirrer mixer. The sealant for organic EL displays with the spacer particles dispersed therein was applied to the center of glass substrate A, and then glass substrate B was attached in a crosswise manner and pressed to make the thickness uniform. The amount of the sealant applied was adjusted so that the sealant for organic EL displays would have a circular shape with a diameter of 5.0 to 7.0 mm after being pressed to make the thickness uniform. The surfaces of glass substrates A and B, each 60 mm long, 30 mm wide, and 5 mm thick, were washed with acetone and then dried. Next, ultraviolet light with a wavelength of 365 nm and 3000 mJ / cm was applied using a UV-LED irradiation device. 2 After irradiation, the sealant for an organic EL display element was cured by heating at 100° C. for 30 minutes to bond the glass substrate A and the glass substrate B together, thereby obtaining a test piece for evaluating adhesion. The obtained test piece was placed with glass substrate B facing downward, and both ends of glass substrate A were fixed from below. Both ends of glass substrate B were compressed from above using a precision universal testing machine at 23°C and a speed of 5 mm / min, thereby measuring the adhesive strength between glass substrate A and glass substrate B. The compression points were centered at positions 7.25 mm from both ends of glass substrate B, within an area 20 mm long and 5 mm wide. The precision universal testing machine used was an Autograph AG-Xplus (manufactured by Shimadzu Corporation).

[0087] (curing rate) Example Reference exampleand 、 Each of the sealants for organic EL display elements obtained in the comparative examples was heated at 100° C. for 30 minutes to cure the sealant for organic EL display elements by heat alone. The sealant for organic EL display elements before curing and the cured product were subjected to FT-IR analysis using a Fourier transform infrared spectrophotometer. -1 The rate of decrease in the peak after curing (reaction rate of epoxy groups) was calculated as the curing rate. The Fourier transform infrared spectrophotometer used was iS-5 (manufactured by Nicolet).

[0088] (Curing distance of the light-shielding part) Example Reference example and 、 Each of the organic EL display element sealants obtained in the comparative examples was applied to the center of the release surface of a release PET film, which was then attached from above. The top and bottom were then sandwiched between glass substrates, and pressure was applied to make the thickness uniform. PET50x1-C (Nippa Corporation, thickness: 50 μm) was used as the release PET film. After pressing, the glass substrate was removed, and black vinyl tape was attached to one side of the non-release surface of the release PET film sandwiching each of the organic EL display element sealants. A metal plate (made of SUS304) with a 1.0 mm thick, 1.0 mm diameter hole was placed on one side of the non-release surface of the release PET film opposite the side with the black vinyl tape attached, with the hole positioned above the organic EL display element sealant. A UV-LED irradiation device was used to irradiate the metal plate with 365 nm ultraviolet light at 3000 mJ / cm2. 2 The UV-LED irradiation device used was a surface irradiation type. After the UV irradiation, the sample was left to stand for 5 minutes, the metal plate and the release PET film on the UV-irradiated side were removed, and the uncured portions of each sealant for organic EL display elements were washed away with ethanol to obtain test specimens. For the obtained test pieces, the diameter of each sealant for organic EL display elements that was not washed away and remained in a circular shape on the release PET film was measured, and the value obtained by subtracting 1.0 mm from the measured value and then multiplying it by half was used as the cured distance of the light-shielding part.

[0089] [Table 1]

[0090] [Table 2] [Industrial Applicability]

[0091] According to the present invention, it is possible to provide a sealant for an organic EL display element that has excellent adhesiveness and can be cured sufficiently even when placed in a light-shielding portion.

Claims

1. The composition contains a curable resin, a photocationic polymerization initiator, a thermal cationic polymerization initiator, and a filler, the curable resin contains an alicyclic epoxy compound and an epoxy compound having a flexible skeleton, the epoxy compound having a flexible skeleton is an epoxy compound having at least one structure selected from the group consisting of a lactone ring-opening structure, a polyalkylene oxide structure, a rubber structure derived from a conjugated diene, and a polysiloxane structure; The total content of the alicyclic epoxy compound and the epoxy compound having a flexible skeleton is 60 parts by weight or more in 100 parts by weight of the curable resin. A sealant for an organic EL display element, characterized in that:

2. 2. The sealant for an organic EL display element according to claim 1, wherein the epoxy compound having a flexible skeleton is an epoxy compound having a polyalkylene oxide structure.

3. 3. The sealant for an organic EL display element according to claim 2, wherein the epoxy compound having a flexible skeleton is a compound represented by the following formula (1): 【Chemistry 1】 In formula (1), X represents an ethyleneoxyethyl group, a di(ethyleneoxy)ethyl group, a tri(ethyleneoxy)ethyl group, a tetra(ethyleneoxy)ethyl group, a propyleneoxypropyl group, a di(propyleneoxy)propyl group, a tri(propyleneoxy)propyl group, a tetra(propyleneoxy)propyl group, a butyleneoxybutyl group, a di(butyleneoxy)butyl group, a tri(butyleneoxy)butyl group, a tetra(butyleneoxy)butyl group, or an alkylene group having from 2 to 15 carbon atoms; and n is 1 to 10.

4. 4. The sealant for an organic EL display element according to claim 1, wherein the photocationic polymerization initiator is a salt having tetrakis(pentafluorophenyl)borate as a counter anion.

5. 5. The sealant for an organic EL display element according to claim 1, wherein the thermal cationic polymerization initiator is a salt having tetrakis(pentafluorophenyl)borate as a counter anion.

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