TWI846809B - Sealant for organic EL display components - Google Patents

Abstract

The purpose of the present invention is to provide a sealant for an organic EL display element that has low outgassing and excellent coating properties and can obtain an organic EL display element with excellent light extraction efficiency. The present invention is a sealant for an organic EL display element containing a cationic polymerizable compound and a cationic polymerization initiator, wherein the cationic polymerizable compound includes a cycloalkene oxide type alicyclic epoxy compound and a fluorene type epoxy compound.

Description

Sealant for organic EL display components

The present invention relates to a sealant for an organic EL display element which has low outgassing properties and excellent coating properties and can obtain an organic EL display element with excellent light extraction efficiency.

An organic electroluminescent (hereinafter referred to as "organic EL") display element has a laminate structure in which an organic luminescent material layer is sandwiched between a pair of electrodes facing each other. Electrons are injected from one electrode and holes are injected from the other electrode into the organic luminescent material layer, thereby causing the electrons and holes to combine in the organic luminescent material layer to emit light. Since such an organic EL display element is self-luminescent, it has the following advantages over liquid crystal display elements that require a backlight: good visual recognition, thinner design, and DC low voltage drive.

The organic light-emitting material layer or electrode constituting the organic EL display element has the problem that its characteristics are easily degraded by moisture, oxygen, etc. Therefore, in order to obtain a practical organic EL display element, the organic light-emitting material layer or electrode must be blocked from the atmosphere to extend its life. As a method of blocking the organic light-emitting material layer or electrode from the atmosphere, the organic EL display element has been sealed with a sealant (for example, Patent Document 1). When the organic EL display element is sealed with a sealant, the following method is usually used to fully suppress the penetration of moisture, oxygen, etc.: an inorganic material film called a passivation film is provided on a laminate having an organic light-emitting material layer, and the inorganic material film is sealed with a sealant.

In recent years, top-emission organic EL display elements have attracted attention, replacing bottom-emission organic EL display elements, which extract light emitted from an organic luminescent material layer from the substrate surface side on which the luminescent element is formed, while top-emission organic EL display elements extract light from the upper side of the organic luminescent layer. This method has the advantage of long life due to its high aperture ratio and low voltage drive. In such top-emission organic EL display elements, since the upper side of the luminescent layer must be transparent, a transparent moisture-proof substrate such as glass is laminated on the upper side of the luminescent element through a transparent sealing layer to seal it (for example, Patent Document 2). However, even when using a transparent moisture-proof substrate or sealant with high transparency, the top-emitting organic EL display element has the following problems: sometimes the efficiency of extracting light emitted from the laminate is poor due to the difference in refractive index between the electrode or passivation film and the sealant. In addition, conventional sealants have the problem of outgassing and deteriorating the element, or poor coating properties. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2007-115692 [Patent Document 2] Japanese Patent Publication No. 2009-051980

[The problem that the invention wants to solve]

The purpose of the present invention is to provide a sealant for an organic EL display element that has low outgassing properties and excellent coating properties, and can obtain an organic EL display element with excellent light extraction efficiency. [Means for solving the problem]

The present invention is a sealant for an organic EL display element containing a cationic polymerizable compound and a cationic polymerization initiator, wherein the cationic polymerizable compound includes a cycloalkene oxide type alicyclic epoxy compound and a fluorene type epoxy compound. The present invention is described in detail below.

The inventors of the present invention have studied the use of cycloolefin oxide type alicyclic epoxy compounds as cationically polymerizable compounds in sealants for organic EL display elements to improve coating properties and prevent outgassing. However, although such sealants using cycloolefin oxide type alicyclic epoxy compounds are excellent in preventing outgassing, they have a problem of reduced light extraction efficiency due to reflection at the interface between the electrode or passivated film and the sealant due to the large difference in refractive index with the electrode or passivated film. Therefore, the inventors of the present invention have studied the use of a combination of the cycloolefin oxide type alicyclic epoxy compounds and fluorene type epoxy compounds as cationically polymerizable compounds. As a result, the inventors have found that it is possible to obtain a sealing agent for an organic EL display element which has low outgassing properties and excellent coating properties and can make the obtained organic EL display element excellent in light extraction efficiency, thereby completing the present invention.

The sealant for an organic EL display element of the present invention contains a cationically polymerizable compound. The cationically polymerizable compound includes an cycloolefin oxide type alicyclic epoxy compound. By containing the cycloolefin oxide type alicyclic epoxy compound, the sealant for an organic EL display element of the present invention has low outgassing and excellent coating properties.

Examples of the cycloolefin oxide type alicyclic epoxy compounds include 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and bis(3,4-epoxycyclohexylmethyl)ether.

Among the above-mentioned cycloolefin oxide type alicyclic epoxy compounds, commercially available ones include celloxide 2021P (manufactured by Daicellul Corporation) and the like.

The content of the above-mentioned cycloolefin oxide type alicyclic epoxy compound in the total 100 parts by weight of the above-mentioned cationically polymerizable compound is preferably 10 parts by weight at the lower limit and 90 parts by weight at the upper limit. When the content of the above-mentioned cycloolefin oxide type alicyclic epoxy compound is 10 parts by weight or more, the obtained sealant for the organic EL display element has low outgassing and better coating properties. When the content of the above-mentioned cycloolefin oxide type alicyclic epoxy compound is 90 parts by weight or less, the obtained organic EL display element has better light extraction efficiency. The better lower limit of the content of the cycloolefin oxide type alicyclic epoxy compound is 15 parts by weight, the better upper limit is 70 parts by weight, the further better lower limit is 20 parts by weight, the further better upper limit is 65 parts by weight, and the particularly better lower limit is 60 parts by weight.

The cationically polymerizable compound includes a fluorene-type epoxy compound. By including the fluorene-type epoxy compound, the sealant for an organic EL display element of the present invention has a small refractive index difference with an electrode or a passivation film, and as a result, the obtained organic EL display element has excellent light extraction efficiency.

The fluorene-based epoxy compound may be any epoxy compound having a fluorene skeleton, and various fluorene-based epoxy compounds may be appropriately selected from the viewpoints of viscosity, refractive index, photocurability, and the like.

The preferred lower limit of the epoxy equivalent of the fluorene-type epoxy compound is 200, and the preferred upper limit is 400. By setting the epoxy equivalent of the fluorene-type epoxy compound to be within this range, the obtained sealant for the organic EL display element has better adhesion, low outgassing and coating properties. In addition, in this specification, the epoxy equivalent of the fluorene-type epoxy compound means (molecular weight of the fluorene-type epoxy compound)/(the number of epoxy groups in one molecule of the fluorene-type epoxy compound).

Among the above-mentioned fluorene-type epoxy compounds, commercially available ones include, for example, fluorene-type epoxy compounds manufactured by Nippon Steel & Sumitomo Chemicals, fluorene-type epoxy compounds manufactured by Nagase Chemicals, and fluorene-type epoxy compounds manufactured by Osaka Gas Chemicals. As the above-mentioned fluorene-type epoxy compounds manufactured by Nippon Steel & Sumitomo Chemicals, for example, ESF-300, etc. can be mentioned. As the above-mentioned fluorene-type epoxy compounds manufactured by Nagase Chemicals, for example, ONCOAT EX-1010, etc. can be mentioned. As the above-mentioned fluorene-type epoxy compounds manufactured by Osaka Gas Chemicals, for example, OGSOL PG-100, EG-200, etc. can be mentioned. These fluorene-type epoxy compounds can be used alone or in combination of two or more.

The preferred lower limit of the content of the fluorene-type epoxy compound in 100 parts by weight of the total cationic polymerizable compound is 10 parts by weight, and the preferred upper limit is 80 parts by weight. When the content of the fluorene-type epoxy compound is 10 parts by weight or more, the obtained organic EL display element has a better light extraction efficiency. When the content of the fluorene-type epoxy compound is 80 parts by weight or less, the obtained sealant for the organic EL display element has a better low outgassing property and coating property. The preferred lower limit of the content of the fluorene-type epoxy compound is 15 parts by weight, the preferred upper limit is 75 parts by weight, the further preferred lower limit is 20 parts by weight, and the further preferred upper limit is 70 parts by weight. Furthermore, from the viewpoint of making the obtained organic EL display element have a further improved light extraction efficiency, the lower limit of the content of the fluorene-type epoxy compound is preferably 30 parts by weight, more preferably 35 parts by weight, and still more preferably 40 parts by weight.

The above-mentioned cationically polymerizable compound may include other cationically polymerizable compounds in addition to the above-mentioned cycloolefin oxide type alicyclic epoxy compounds and the above-mentioned fluorene type epoxy compounds. As the above-mentioned other cationically polymerizable compounds, for example, other epoxide compounds, cyclobutane compounds, vinyl ether compounds, etc. other than the above-mentioned cycloolefin oxide type alicyclic epoxy compounds and the above-mentioned fluorene type epoxy compounds can be listed.

Examples of the other epoxy compounds include 1,7-octadiene diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, trihydroxymethylpropane triglycidyl ether, phenyl glycidyl ether, and phenylene diglycidyl ether.

Examples of the cyclohexane compound include 3-ethyl-3-(((3-ethylcyclohexane-3-yl)methoxy)methyl)cyclohexane, 3-ethyl-3-((2-ethylhexyloxy)methyl)cyclohexane, 3-ethyl-3-((3-(triethoxysilyl)propoxy)methyl)cyclohexane, phenol novolac cyclohexane, and 1,4-bis(((3-ethyl-3-cyclohexane-3-yl)methoxy)methyl)benzene.

Examples of the vinyl ether compound include benzyl vinyl ether, cyclohexanedimethanol monovinyl ether, dicyclopentadiene vinyl ether, 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, dipropylene glycol divinyl ether, and tripropylene glycol divinyl ether.

Among them, as the other cationically polymerizable compound, at least one selected from the group consisting of 3-ethyl-3-(((3-ethylcyclohexyl-3-yl)methoxy)methyl)cyclohexylene, 1,2:7,8-diexyloxyoctane and 1,2:5,6-diexyloxyoctane is preferred, and 3-ethyl-3-(((3-ethylcyclohexyl-3-yl)methoxy)methyl)cyclohexylene is more preferred.

When the above-mentioned cationic polymerizable compound contains the above-mentioned other cationic polymerizable compounds, the content of the above-mentioned other cationic polymerizable compounds in 100 parts by weight of the above-mentioned cationic polymerizable compounds is preferably 10 parts by weight, and the preferably upper limit is 50 parts by weight. By having the content of the above-mentioned other cationic polymerizable compounds in this range, the obtained sealant for organic EL display elements has better adhesion and coating properties. The content of the above-mentioned other cationic polymerizable compounds is more preferably 45 parts by weight, and the more preferably upper limit is 40 parts by weight. Furthermore, when the above-mentioned cationically polymerizable compound contains the above-mentioned other cationically polymerizable compounds, the combined content of the above-mentioned cycloolefin oxide type alicyclic epoxy compound and the above-mentioned other cationically polymerizable compounds in 100 parts by weight of the above-mentioned cationically polymerizable compound is preferably 20 parts by weight. By making the combined content of the above-mentioned cycloolefin oxide type alicyclic epoxy compound and the above-mentioned other cationically polymerizable compounds more than 20 parts by weight, the obtained sealant for organic EL display elements has better coating properties. The combined content of the above-mentioned cycloolefin oxide type alicyclic epoxy compound and the above-mentioned other cationically polymerizable compounds is more preferably 30 parts by weight, and the further more preferably 40 parts by weight.

The sealant for the organic EL display element of the present invention contains a cationic polymerization initiator. As the above-mentioned cationic polymerization initiator, a thermal cationic polymerization initiator or a photo-cationic polymerization initiator can be cited.

As the above-mentioned thermal cationic polymerization initiator, there can be mentioned coronium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, etc., whose anion part is composed of _BF4- ^, _PF6- ^, _SbF6- ^or ( _BX4 ) ^- (wherein X represents a phenyl group substituted with at least two fluorine or trifluoromethyl groups). Among them, coronium salts are preferred.

Examples of the coronium salt include triphenylcoronium tetrafluoroborate and triphenylcoronium hexafluoroantimonate.

Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantibonate and tetrabutylphosphonium hexafluoroantibonate.

Examples of the ammonium salt 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 tetrakis (pentafluorophenyl) borate, Benzyl)ammonium hexafluorotetrafluoroborate, methylphenyldibenzylammonium hexafluorophosphate, methylphenyldibenzylammonium hexafluoroantimonylate, methylphenyldibenzylammonium tetra(pentafluorophenyl)borate, phenyltribenzylammonium tetra(pentafluorophenyl)borate, dimethylphenyl (3,4-dimethylbenzyl)ammonium tetra(pentafluorophenyl)borate, N,N-dimethyl-N-benzylaniline (benzyl anilinium) hexafluoroantimonylate, N,N-diethyl-N-benzylaniline tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonylate, N,N-diethyl-N-benzylpyridinium trifluoromethanesulfonic acid, etc.

As the thermal cationic polymerization initiator, commercially available ones include, for example, the thermal cationic polymerization initiator manufactured by Sanshin Chemical Industry Co., Ltd. and the thermal cationic polymerization initiator manufactured by King Industries, etc. As the thermal cationic polymerization initiator manufactured by Sanshin Chemical Industry Co., Ltd., for example, SAN-AID SI-60, SAN-AID SI-80, SAN-AID SI-B3, SAN-AID SI-B3A, SAN-AID SI-B4, etc. As the thermal cationic polymerization initiator manufactured by King Industries, for example, CXC-1612, CXC-1821, etc.

The photocatalytic ion polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid when exposed to light, and may be an ionic photoacid generating type or a non-ionic photoacid generating type.

Examples of the anion part of the ionic photoacid generating type photocatalytic polymerization initiator include _BF4- ^, _PF6- , _SbF6- ^, ( _BX4 ) ^- (wherein X represents a phenyl group substituted with at least two fluorine or trifluoromethyl groups), etc. Examples of the anion part include _PFm ( _{CnF2n +1} ) ⁶ _-m- ⁽ wherein m is an integer of 0 to 5, and n is an integer of 1 to 6), etc. Examples of the ionic photoacid generating type photocatalytic polymerization initiator include aromatic cobalt salts, aromatic iodine salts, aromatic diazonium salts, aromatic ammonium salts, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salts, etc. having the above-mentioned anionic moiety.

Examples of the aromatic thionium salt include bis(4-(diphenyldihydrothio)phenyl) sulfide bis(hexafluorophosphate), bis(4-(diphenyldihydrothio)phenyl) sulfide bis(hexafluoroantimonate), bis(4-(diphenyldihydrothio)phenyl) sulfide bis(tetrafluoroborate), bis(4-(diphenyldihydrothio)phenyl) sulfide bis(tetrafluoroborate), and bis(4-(diphenyldihydrothio)phenyl) sulfide bis(hexafluoroantimonate). Thioether tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylcopperamide hexafluorophosphate, diphenyl-4-(phenylthio)phenylcopperamide hexafluoroantimonate, diphenyl-4-(phenylthio)phenylcopperamide tetrafluoroborate, diphenyl-4-(phenylthio)phenylcopperamide tetrakis(pentafluorophenyl)borate, triphenylcopperamide hexafluorophosphate 、Triphenylsiron hexafluoroantimonylate、Triphenylsiron tetrafluoroborate、Triphenylsiron tetrakis(pentafluorophenyl)borate、Bis(4-(bis(4-(2-hydroxyethoxy))phenyldihydrosulfide)phenyl)sulfide bis(hexafluorophosphate)、Bis(4-(bis(4-(2-hydroxyethoxy))phenyldihydrosulfide)phenyl)sulfide bis(hexafluoroantimonylate) , bis(4-(bis(4-(2-hydroxyethoxy))phenyldihydrothio)phenyl)sulfide bistetrafluoroborate, bis(4-(bis(4-(2-hydroxyethoxy))phenyldihydrothio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, tris(4-(4-acetylphenyl)phenylthio)copper tetrakis(pentafluorophenyl)borate, etc. Among them, triarylsirconium tetrakis(pentafluorophenyl)borates such as triphenylsirconium tetrakis(pentafluorophenyl)borates are preferred.

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

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

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 tetrakis(pentafluorophenyl)borate, and the like.

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.

Examples of the non-ionic photoacid generating type photocatalytic polymerization initiator include nitrobenzyl esters, sulfonic acid derivatives, phosphoric acid esters, phenolsulfonates, diazonaphthoquinones, and N-hydroxyimidesulfonates.

Examples of the above-mentioned photocatalytic polymerization initiators that are commercially available include photocatalytic polymerization initiators manufactured by Midori Kagaku, photocatalytic polymerization initiators manufactured by Union Carbide, photocatalytic polymerization initiators manufactured by Aidico, photocatalytic polymerization initiators manufactured by 3M, photocatalytic polymerization initiators manufactured by BASF, photocatalytic polymerization initiators manufactured by Solvay, and photocatalytic polymerization initiators manufactured by Sanya Pro. Examples of the above-mentioned photocatalytic polymerization initiators manufactured by Midori Kagaku include DTS-200, etc. Examples of the photocatalytic polymerization initiator manufactured by the Union Carbide Company include UVI6990 and UVI6974. Examples of the photocatalytic polymerization initiator manufactured by the Adecco Company include SP-150 and SP-170. Examples of the photocatalytic polymerization initiator manufactured by the 3M Company include FC-508 and FC-512. Examples of the photocatalytic polymerization initiator manufactured by the BASF Company include IRGACURE261 and IRGACURE290. Examples of the photocatalytic polymerization initiator manufactured by the Solvay Company include PI2074. Examples of the photocatalytic ion polymerization initiators manufactured by the above-mentioned Sanya Pro Corporation include CPI-100P, CPI-200K, and CPI-210S.

Among the above cationic polymerization initiators, a borate-based quaternary ammonium salt (hereinafter also referred to as "borate-based quaternary ammonium salt") is more suitable. The counter anion of the borate-based quaternary ammonium salt is preferably BF ₄ ^- or (BX ₄ ) ^- (where X represents a phenyl group substituted with at least two fluorine or trifluoromethyl groups).

The content of the cationic polymerization initiator is preferably 0.05 parts by weight and 10 parts by weight relative to 100 parts by weight of the cationic polymerizable compound. When the content of the cationic polymerization initiator is within this range, the obtained sealant for organic EL display elements has better curability, storage stability and moisture resistance of the cured product. The better lower limit of the content of the cationic polymerization initiator is 0.1 parts by weight and the better upper limit is 5 parts by weight.

The sealant for the organic EL display element of the present invention may also contain a thermosetting agent. As the above-mentioned thermosetting agent, for example, hydrazide compounds, imidazole derivatives, acid anhydrides, dicyandiamide, guanidine derivatives, modified aliphatic polyamines, addition products of various amines and epoxy resins, etc. can be listed. As the above-mentioned hydrazide compounds, for example, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylalantoin, sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, malonic acid dihydrazide, etc. can be listed. Examples of the above-mentioned imidazole derivatives include 1-cyanoethyl-2-phenylimidazole, N-(2-(2-methyl-1-imidazolyl)ethyl)urea, 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-symmetric tris(imidazolyl), N,N'-bis(2-methyl-1-imidazolylethyl)urea, N,N'-(2-methyl-1-imidazolylethyl)-hexamethylenediamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2-phenyl-4,5-dihydroxymethylimidazole. Examples of the above-mentioned acid anhydride include tetrahydrophthalic anhydride and ethylene glycol bis(anhydrotrimellitate). These thermosetting agents may be used alone or in combination of two or more.

Examples of the thermosetting agents commercially available include thermosetting agents manufactured by Otsuka Chemical Co., Ltd. and thermosetting agents manufactured by Ajinomoto Fine-Techno Co., Ltd. Examples of the thermosetting agents manufactured by Otsuka Chemical Co., Ltd. include SDH and ADH. Examples of the thermosetting agents manufactured by Ajinomoto Fine-Techno Co., Ltd. include Ajicure VDH, Ajicure VDH-J, and Ajicure UDH.

The content of the above-mentioned thermosetting agent is preferably 0.5 parts by weight and the upper limit is 30 parts by weight relative to 100 parts by weight of the above-mentioned cationic polymerizable compound. When the content of the above-mentioned thermosetting agent is 0.5 parts by weight or more, the obtained sealant for the organic EL display element has better thermosetting properties. When the content of the above-mentioned thermosetting agent is 30 parts by weight or less, the obtained sealant for the organic EL display element has better storage stability and the cured product has better moisture resistance. The better lower limit of the content of the above-mentioned thermosetting agent is 1 part by weight and the better upper limit is 15 parts by weight.

The sealant for an organic EL display element of the present invention preferably contains a stabilizer. By containing the stabilizer, the sealant for an organic EL display element of the present invention has a more excellent storage stability.

As the above-mentioned stabilizer, an aromatic amine compound can be used. As the above-mentioned aromatic amine compound, for example, benzylamine, amine phenol type epoxy resin, etc. can be listed. As the above-mentioned amine phenol type epoxy resin, triepoxypropyl para-aminophenol, etc. can be listed. Among them, benzylamine is preferred. These stabilizers can be used alone or in combination of two or more.

The content of the stabilizer is preferably 0.001 parts by weight and 2 parts by weight relative to 100 parts by weight of the cationic polymerizable compound. When the content of the stabilizer is within this range, the obtained sealant for an organic EL display element has a better stability while maintaining excellent curability. The better lower limit of the content of the stabilizer is 0.005 parts by weight and the better upper limit is 1 part by weight.

The sealant for organic EL display element of the present invention may also contain a silane coupling agent. The silane coupling agent has the function of improving the adhesion between the sealant for organic EL display element of the present invention and a substrate or the like.

Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-isocyanatepropyltrimethoxysilane, etc. These silane coupling agents may be used alone or in combination of two or more.

The content of the above-mentioned silane coupling agent relative to 100 parts by weight of the above-mentioned cationic polymerizable compound is preferably 0.1 parts by weight and the upper limit is preferably 10 parts by weight. By setting the content of the above-mentioned silane coupling agent within this range, the overflow of the excess silane coupling agent can be suppressed, and at the same time, the effect of improving the adhesion can be made more excellent. The lower limit of the content of the above-mentioned silane coupling agent is more preferably 0.5 parts by weight, and the upper limit is more preferably 5 parts by weight. In addition, from the perspective of low outgassing, the content of the above-mentioned silane coupling agent relative to 100 parts by weight of the above-mentioned cationic polymerizable compound is preferably 0.5 parts by weight, more preferably 0.1 parts by weight, and even more preferably 0.01 parts by weight.

The sealant for the organic EL display element of the present invention may further contain a surface modifier within the scope that does not hinder the purpose of the present invention. By containing the above-mentioned surface modifier, the flatness of the coating film of the sealant for the organic EL display element of the present invention can be improved. As the above-mentioned surface modifier, for example, a surfactant or a leveling agent can be listed.

Examples of the surface modifier include silicone-based, acrylic-based, and fluorine-based agents. Among the surface modifiers listed above, commercially available agents include surface modifiers manufactured by BYK-Chemie Japan and surface modifiers manufactured by AGC Seimei Chemical Co., Ltd. Examples of surface modifiers manufactured by BYK-Chemie Japan include BYK-330, BYK-340, and BYK-345. Examples of surface modifiers manufactured by AGC Seimei Chemical Co., Ltd. include Surflon S-611.

The sealant for an organic EL display element of the present invention may also contain a compound or ion exchange resin that reacts with the acid generated in the sealant for an organic EL display element in order to improve the durability of the element electrode within the scope that does not hinder the purpose of the present invention.

As the compound that reacts with the generated acid, there can be mentioned substances that neutralize with the acid, such as carbonates or bicarbonates of alkali metals, or carbonates or bicarbonates of alkali earth metals, etc. Specifically, for example, calcium carbonate, calcium bicarbonate, sodium carbonate, sodium bicarbonate, etc. can be used.

As the ion exchange resin, any of cation exchange type, anion exchange type, and zwitterionic ion exchange type can be used, and in particular, cation exchange type or anion-cation ion exchange type capable of adsorbing chloride ions is more suitable.

The sealant for the organic EL display element of the present invention may contain a solvent for adjusting the viscosity, etc., but since the residual solvent may cause the organic light-emitting material layer to deteriorate or produce outgassing, it is preferably free of solvent, or the solvent content is less than 0.05 weight %.

Furthermore, 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 regulator, an ultraviolet absorber, and an antioxidant as required.

The viscosity of the sealant for organic EL display elements of the present invention measured by an E-type viscometer at 25°C and 2.5 rpm preferably has an upper limit of 250 Pa·s. By keeping the viscosity below 250 Pa·s, the sealant for organic EL display elements obtained has excellent coating properties. The upper limit of the viscosity is preferably 100 Pa·s, and the upper limit is more preferably 10 Pa·s. In addition, the lower limit of the viscosity is preferably 5 mPa·s. The viscosity can be measured, for example, using VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer and a cone plate of CP1.

Regarding the sealant for organic EL display elements of the present invention, the preferred lower limit of the refractive index of the cured product at the sodium D line at 25°C is 1.55. By setting the refractive index within this range, the refractive index difference with the electrode or passivation film becomes smaller, and as a result, the obtained organic EL display element has excellent light extraction efficiency. The more preferred lower limit of the refractive index is 1.56. The above-mentioned "refractive index of the sodium D line" can be measured using an Abbe refractometer. In addition, as a cured product for measuring the above-mentioned refractive index, for example, a measuring piece with a length of 20 mm, a width of 10 mm, and a thickness of about 0.5 to 1 mm can be used. The hardened material for measuring the refractive index can be obtained by heating at 100°C for 30 minutes if it is a thermosetting sealant, and by heating at 100°C for 30 minutes after irradiating with ultraviolet rays of about 2000mJ/ ^cm2 if it is a photothermosetting sealant.

The sealant for organic EL display elements of the present invention is particularly suitable as an in-plane sealant for covering and sealing a laminate having an organic light-emitting material layer. In addition, the sealant for organic EL display elements of the present invention is suitable for sealing top-emitting organic EL display elements.

As a method for sealing an organic EL display element using the sealant for an organic EL display element of the present invention, for example, there can be cited a method having the following steps: applying the sealant for an organic EL display element of the present invention to a substrate by printing, dispensing, or inkjet method, and curing the applied sealant for an organic EL display element by heating and/or irradiating with light.

In the step of applying the sealant for the organic EL display element of the present invention to the substrate, the sealant for the organic EL display element of the present invention may be applied to the entire surface of the substrate or may be applied to a portion of the substrate. The shape of the sealant for the organic EL display element of the present invention formed by applying is not particularly limited as long as it is a shape that can protect the laminate having the organic light-emitting material layer from the invasion of external gas. It may be a shape that completely covers the laminate, a closed pattern may be formed on the periphery of the laminate, or a pattern with a partially opened portion may be formed on the periphery of the laminate.

When the sealant for the organic EL display element is cured by heating, it is preferably heated at 50° C. or higher and 120° C. or lower in order to reduce damage to the laminate having the organic light-emitting material layer and to sufficiently cure the laminate.

When the sealant for the organic EL display element of the present invention is cured by irradiation with light, the sealant for the organic EL display element of the present invention can be appropriately cured by irradiating light with a wavelength of 300nm to 400nm and a cumulative light amount of 300mJ/ ^cm2 to 3000mJ/ ^cm2 .

As the light source used for the above-mentioned illumination, for example, there can be listed low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, excimer laser, chemical lamp, black light lamp, microwave-excited mercury lamp, metal halogen lamp, sodium lamp, halogen lamp, xenon lamp, LED lamp, fluorescent lamp, sunlight, electron beam irradiation device, etc. These light sources can be used alone or in combination of two or more. These light sources can be appropriately selected in accordance with the absorption wavelength of the above-mentioned photo-cationic polymerization initiator.

As means for irradiating the sealant for an organic EL display element of the present invention with light, for example, there can be cited simultaneous irradiation with various light sources, sequential irradiation with time intervals, and a combination of simultaneous irradiation and sequential irradiation, and any irradiation means can be used.

The cured product obtained by the step of curing the sealant for the organic EL display element by heating and/or irradiating with light may be further coated with an inorganic material film. As the inorganic material constituting the inorganic material film, conventionally known materials may be used, such as silicon nitride ( _SiNx ) or silicon oxide ( _SiOx ). The inorganic material film may be composed of a single layer or may be a laminate of multiple layers. Furthermore, the laminate may be coated with the inorganic material film and the resin film composed of the sealant for the organic EL display element of the present invention by alternating and repeating.

The method for manufacturing the above-mentioned organic EL display element may also include a step of bonding a substrate coated with the sealant for organic EL display element of the present invention (hereinafter, also referred to as "a substrate") to another substrate. The substrate coated with the sealant for organic EL display element of the present invention (hereinafter, also referred to as "a substrate") may be a substrate having a laminate having an organic light-emitting material layer formed thereon, or may be a substrate not having the laminate formed thereon. When the above-mentioned one substrate is the above-mentioned substrate not having a laminate formed thereon, when bonding the above-mentioned other substrate, the sealant for organic EL display element of the present invention may be applied to the above-mentioned one substrate in a manner that can protect the above-mentioned laminate from external gas attack. That is, when bonding another substrate, the sealant portion of the closed pattern can be applied to the entire surface of the position to be the above-mentioned laminate, or when bonding another substrate, the sealant portion of the closed pattern can be formed into a shape that completely surrounds the position to be the above-mentioned laminate. In addition, as a method for sealing the above-mentioned organic EL display element, a so-called dam fill sealing method can be used. That is, first, a curable paste is applied to the substrate of the organic EL display element in a manner surrounding the periphery of the display portion. Then, the organic EL display element of the present invention is coated with a sealant on the inner side of the applied curable paste, and the sealant is prevented from overflowing by the peripheral curable paste, and at the same time, the opposite sealing substrate is bonded. Then, a method of curing the curable paste at the periphery and the sealant for an organic EL display element of the present invention that has been squeezed and diffused to the inside can be used by heating and/or irradiating light.

The step of curing the sealant for the organic EL display element by heating and/or irradiation can be performed before or after the step of laminating the one substrate to the other substrate. When the step of curing the sealant for the organic EL display element by heating and/or irradiation is performed before the step of laminating the one substrate to the other substrate, the sealant for the organic EL display element of the present invention is preferably usable for more than 1 minute after heating and/or irradiation until the curing reaction proceeds and the sealant cannot be continued. By having the usable time of more than 1 minute, a higher bonding strength can be obtained without excessive curing before laminating the one substrate to the other substrate.

In the step of bonding the one substrate to the other substrate, the method of bonding the one substrate to the other substrate is not particularly limited, and it is preferred to bond them in a reduced pressure environment. The preferred lower limit of the vacuum degree in the reduced pressure environment is 0.01 kPa, and the preferred upper limit is 10 kPa. By setting the vacuum degree in the reduced pressure environment to this range, it is possible to more efficiently remove bubbles in the sealant for the organic EL display element of the present invention when bonding the one substrate to the other substrate without taking a long time to achieve a vacuum state due to the airtightness of the vacuum device and the capacity of the vacuum pump. [Effect of the invention]

According to the present invention, a sealant for an organic EL display element can be provided which has low outgassing properties, excellent coating properties, and can obtain an organic EL display element with excellent light extraction efficiency.

The following disclosed embodiments further illustrate the present invention in detail, but the present invention is not limited to these embodiments.

(Examples 1 to 14, Comparative Examples 1 to 3) The materials were stirred and mixed at a stirring speed of 2000 rpm using a stirring mixer according to the blending ratios listed in Tables 1 to 3, thereby preparing the sealing agents for the organic EL display elements of Examples 1 to 14 and Comparative Examples 1 to 3. AR-250 (manufactured by Shinki Corporation) was used as the stirring mixer.

<Evaluation> The following evaluation was performed on each of the sealants for organic EL display elements obtained in the examples and comparative examples. The results are shown in Tables 1 to 3.

(1) Viscosity The viscosity of each organic EL display element sealant obtained in the embodiment and the comparative example was measured at 25°C and 2.5 rpm using an E-type viscometer. VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) was used as the E-type viscometer. In addition, the viscosity of the organic EL display element sealant obtained in Comparative Example 2 could not be measured because it was solid at 25°C.

(2) Storage stability For each sealant for an organic EL display element obtained in the embodiment and the comparative example, the initial viscosity immediately after manufacture and the viscosity after storage at 25°C for one week were measured at 25°C using an E-type viscometer, and (viscosity after storage at 25°C for one week)/(initial viscosity) was derived as the viscosity change rate. As an E-type viscometer, VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) was used. The storage stability was evaluated by assigning "◎" to a viscosity change rate of less than 1.2, "○" to a viscosity change rate of 1.2 or more but less than 1.5, "△" to a viscosity change rate of 1.5 or more but less than 2.0, and "×" to a viscosity change rate of 2.0 or more. In addition, since the sealant for an organic EL display element obtained in Comparative Example 2 is solid at 25°C, the storage stability cannot be evaluated.

(3) Coating properties For each of the 100 parts by weight of the sealant for the organic EL display element obtained in the embodiment and the comparative example, 0.3 parts by weight of polymer beads with an average particle size of 10 μm were added and uniformly dispersed using a planetary stirring device. Micro pearl SP (manufactured by Sekisui Chemical Industries) was used as the polymer beads. Two glass substrates with a length of 5 cm and a width of 5 cm were prepared, and 0.1 mL of the obtained dispersion was placed in the center of one of the glass substrates and overlapped with the other glass substrate. A 100 g weight was placed on the other glass substrate to squeeze and diffuse the sealant, and after being placed on a hot plate at 60°C for 10 minutes, the weight was removed and the diameter of the diffusion between the glass substrates was measured. The coating properties were evaluated by marking "◎" for a diameter of 30 mm or more, "○" for a diameter of 25 mm or more but less than 30 mm, "△" for a diameter of 20 mm or more but less than 25 mm, and "×" for a diameter less than 20 mm.

(4) Curability The encapsulants for organic EL display elements obtained in the examples and comparative examples were cured by heating at 100°C for 30 minutes, and the reaction rate of the epoxy group (the reduction rate of the peak from the epoxy group) at that time was measured using an infrared spectrometer. In addition, the encapsulant for organic EL display elements obtained in Example 13 was cured by irradiating the encapsulant with ultraviolet light of 1500 mJ/ ^cm2 at a wavelength of 365 nm using a UV-LED. The encapsulant was then cured by heating at 90°C for 30 minutes. As the infrared spectrometer, UMA600 (manufactured by Agilent Technologies) was used. The curability was evaluated by making the case where the reaction rate of the epoxy group was 90% or more "◎", the case where it was 80% or more but less than 90% "○", the case where it was 60% or more but less than 80% "△", and the case where it was less than 60% "×".

(5) Refractive index and light extraction efficiency A 1 mm thick silicone rubber sheet was hollowed out into a rectangular shape of 20 mm in length and 10 mm in width to prepare a mold. This mold was placed on a release PET film, and each organic EL display element obtained in the embodiment and the comparative example was filled into the mold with a sealant. The mold was then covered with another release PET film in a manner that did not leave any bubbles to obtain a laminate. The obtained laminate was sandwiched between two glass plates and fixed. The sealant was cured by heating in an oven at 100°C for 30 minutes. The PET film was then peeled off and the cured sealant was taken out from the silicone rubber sheet to obtain a test piece of 10 mm in length, 20 mm in width and 1 mm in thickness. In addition, the sealant for the organic EL display element obtained in Example 13 was irradiated with 1500mJ/ ^cm2 of ultraviolet light with a wavelength of 365nm using a UV-LED, and then heated at 90°C for 30 minutes to cure. The refractive index of the obtained test piece was measured at 25°C using an Abbe refractometer. As the Abbe refractometer, NAR-4T (manufactured by Atago Co., Ltd.) was used. In addition, considering the refractive index difference with the electrode or the passivated film, the case where the refractive index is 1.55 or more is "○", the case where it is 1.53 or more but less than 1.55 is "△", and the case where it is less than 1.53 is "×" to evaluate the light extraction efficiency.

(6) Low outgassing property 300 mg of each organic EL display element sealant obtained in the examples and comparative examples was sealed in a vial, and then heated at 100°C for 30 minutes to cure. In addition, the organic EL display element sealant obtained in Example 13 was irradiated with 1500 mJ/ ^cm2 of ultraviolet light with a wavelength of 365 nm using a UV-LED, and then heated at 90°C for 30 minutes to cure. The vial was heated in a constant temperature oven at 85°C for 100 hours, and the amount of vaporized components in the vial was measured using a gas chromatography mass spectrometer. As a gas chromatography mass spectrometer, JMS-Q1050 (manufactured by NEC Corporation) was used. The low outgassing property was evaluated by marking "○" for a gasification component amount of less than 50 ppm, "△" for a gasification component amount of 50 ppm or more but less than 100 ppm, and "×" for a gasification component amount of more than 100 ppm.

[Table 1] Embodiment 1 2 3 4 5 6 7 Composition (parts by weight) Cationic polymerizable compounds 3',4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (manufactured by Daicellul Corporation, "celloxide2021P") 25 30 20 15 20 38 67 Fluorene-type epoxy compound (manufactured by Osaka Gas Chemical Co., Ltd., "OGSOL EG-200") 50 68 60 75 67 50 30 Bisphenol A epoxy compound (manufactured by DIC Corporation, "EPICLON EXA-850CRP") - - - - - - - 3-Ethyl-3-(((3-ethylcyclohexane-3-yl)methoxy)methyl)cyclohexane (Toagosei Co., Ltd., "ARON OXETANE OXT-221") 25 2 20 10 13 12 3 Cationic polymerization initiator Borate-based quaternary ammonium salt (manufactured by King Industries, "CXC-1821") 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Antimonate-based cobalt salt (Sanshin Chemical Industry Co., Ltd., "SAN-AID SI-60") - - - - - - - Antimonate-based quaternary ammonium salt (manufactured by King Industries, "CXC-1612") - - - - - - - Borate-based iodine salt (manufactured by Solvay, "PI2074") - - - - - - - Reviews Viscosity (Pa・s) 20 65 86 215 35 51 1.6 Preserve stability ○ ○ ○ ○ ○ ○ ◎ Paintability ◎ ◎ ◎ ○ ◎ ◎ ◎ Hardening ○ ○ ○ ○ ○ ○ ○ Refractive index (light extraction efficiency) 1.57 (○) 1.59 (○) 1.58 (○) 1.60 (○) 1.59 (○) 1.57 (○) 1.55 (○) Low outgassing ○ ○ ○ ○ ○ ○ ○

[Table 2] Embodiment 8 9 10 11 12 13 14 Composition (parts by weight) Cationic polymerizable compounds 3',4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (manufactured by Daicellul Corporation, "celloxide2021P") 10 60 80 25 25 25 90 Fluorene-type epoxy compound (manufactured by Osaka Gas Chemical Co., Ltd., "OGSOL EG-200") 90 20 20 50 50 50 10 Bisphenol A epoxy compound (manufactured by DIC Corporation, "EPICLON EXA-850CRP") - - - - - - - 3-Ethyl-3-(((3-ethylcyclohexane-3-yl)methoxy)methyl)cyclohexane (Toagosei Co., Ltd., "ARON OXETANE OXT-221") - 20 - 25 25 25 - Cationic polymerization initiator Borate-based quaternary ammonium salt (manufactured by King Industries, "CXC-1821") 0.5 0.5 0.5 - - - 0.5 Antimonate-based cobalt salt (Sanshin Chemical Industry Co., Ltd., "SAN-AID SI-60") - - - 0.5 - - - Antimonate-based quaternary ammonium salt (manufactured by King Industries, "CXC-1612") - - - - 0.5 - - Borate-based iodine salt (manufactured by Solvay, "PI2074") - - - - - 0.5 - Reviews Viscosity (Pa・s) More than 1000 0.5 0.8 20 20 twenty one 0.6 Preserve stability ○ ○ ◎ △ △ ◎ ◎ Paintability △ ◎ ◎ ◎ ◎ ◎ ◎ Hardening ○ ○ ○ ○ ○ △ ○ Refractive index (light extraction efficiency) 1.61 (○) 1.54 (△) 1.54 (△) 1.57 (○) 1.57 (○) 1.57 (○) 1.53 (△) Low outgassing ○ ○ ○ ○ ○ ○ ○

[table 3] Comparison Example 1 2 3 Composition (parts by weight) Cationic polymerizable compounds 3',4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (manufactured by Daicellul Corporation, "celloxide2021P") 96 - 20 Fluorene-type epoxy compound (manufactured by Osaka Gas Chemical Co., Ltd., "OGSOL EG-200") - 100 - Bisphenol A epoxy compound (manufactured by DIC Corporation, "EPICLON EXA-850CRP") - - 65 3-Ethyl-3-(((3-ethylcyclohexane-3-yl)methoxy)methyl)cyclohexane (Toagosei Co., Ltd., "ARON OXETANE OXT-221") 3 - 15 Cationic polymerization initiator Borate-based quaternary ammonium salt (manufactured by King Industries, "CXC-1821") 0.5 0.5 0.5 Antimonate-based cobalt salt (Sanshin Chemical Industry Co., Ltd., "SAN-AID SI-60") - - - Antimonate-based quaternary ammonium salt (manufactured by King Industries, "CXC-1612") - - - Borate-based iodine salt (manufactured by Solvay, "PI2074") - - - Reviews Viscosity (Pa・s) 0.3 Unable to determine 0.9 Preserve stability ◎ Unable to determine ○ Paintability ◎ × ◎ Hardening ○ ○ ○ Refractive index (light extraction efficiency) 1.52 (×) 1.62 (○) 1.56 (○) Low outgassing ○ ○ × [Industrial Availability]

According to the present invention, a sealant for an organic EL display element can be provided which has low outgassing properties, excellent coating properties, and can obtain an organic EL display element with excellent light extraction efficiency.

without

without

Claims (7)

A sealant for an organic EL display element, which contains a cationic polymerizable compound and a cationic polymerization initiator, wherein the cationic polymerizable compound comprises a cycloalkene oxide type alicyclic epoxy compound and a fluorene type epoxy compound, and the content of the fluorene type epoxy compound is less than 75 parts by weight in 100 parts by weight of the cationic polymerizable compound. As in claim 1, the sealant for an organic EL display element, wherein the content of the cycloolefin oxide type alicyclic epoxy compound in 100 parts by weight of the total cationically polymerizable compound is greater than 10 parts by weight and less than 90 parts by weight, and the content of the fluorene type epoxy compound is greater than 10 parts by weight. As in claim 1 or 2, the sealant for an organic EL display element, wherein the cationically polymerizable compound includes other cationically polymerizable compounds in addition to the cycloolefin oxide type alicyclic epoxy compound and the fluorene type epoxy compound. The sealant for an organic EL display element as claimed in claim 3 contains at least one selected from the group consisting of 3-ethyl-3-(((3-ethylcyclohexane-3-yl)methoxy)methyl)cyclohexane, 1,2:7,8-diepoxyoctane and 1,2:5,6-diepoxycyclooctane as the other cationically polymerizable compound. The sealant for an organic EL display element as claimed in claim 4 contains 3-ethyl-3-(((3-ethylcyclohexylbutane-3-yl)methoxy)methyl)cyclohexylbutane as the other cationically polymerizable compound. As in claim 3, the sealant for an organic EL display element, wherein the content of the other cationically polymerizable compound in 100 parts by weight of the cationically polymerizable compound is greater than 10 parts by weight and less than 50 parts by weight. As in claim 1 or 2, the sealant for an organic EL display element, wherein the cationic polymerization initiator contains a quaternary ammonium salt of a borate system as a counter anion.