KR102658948B1 - Encapsulant for organic EL display elements - Google Patents

Abstract

The purpose of the present invention is to provide an encapsulant for an organic EL display element that can be easily applied by an inkjet method, has excellent low outgassing properties, and can produce an organic EL display element with excellent reliability. .
The present invention provides an encapsulant for an organic EL display element containing a polymerizable compound, wherein the polymerizable compound comprises a high boiling point polymerizable compound with a boiling point of 300°C or higher and a reactive functional group capable of reacting with the high boiling point polymerizable compound. and further contains a low boiling point polymerizable compound having a boiling point of less than 300°C, wherein the low boiling point polymerizable compound is at least selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds. 1 type, the content of the low boiling point polymerizable compound in 100 parts by weight of the polymerizable compound is 1 part by weight or more and 20 parts by weight or less, and the haze of the cured product with a thickness of 10 μm is 1.0% or less. am.

Description

Encapsulant for organic EL display elements

The present invention relates to an encapsulant for an organic EL display element that can be easily applied by an inkjet method, has excellent low outgassing properties, and can produce an organic EL display element with excellent reliability.

An organic electroluminescence (hereinafter also referred to as “organic EL”) display element has a laminate structure in which an organic light-emitting material layer is sandwiched between a pair of opposing electrodes, and one electrode is attached to the organic light-emitting material layer. As electrons are injected from one electrode and holes are injected from the other electrode, electrons and holes combine in the organic light-emitting material layer to emit light. In this way, since organic EL display elements self-emit, they have the advantage of having good visibility, being able to be thinned, and driving at low direct current voltages compared to liquid crystal display elements that require a backlight.

The organic light-emitting material layer or electrode that constitutes the organic EL display element has a problem in that its characteristics are easily deteriorated by moisture, oxygen, etc. Therefore, in order to obtain a practical organic EL display element, it is necessary to block the organic light emitting material layer or electrode from the atmosphere to achieve a longer lifespan. Patent Document 1 discloses a method of sealing the organic light-emitting material layer and electrode of an organic EL display element with a laminated film of a silicon nitride film and a resin film formed by a CVD method. Here, the resin film plays a role in preventing pressure on the organic layer or electrode due to internal stress of the silicon nitride film.

In the method of encapsulating with a silicon nitride film disclosed in Patent Document 1, when forming a silicon nitride film due to irregularities on the surface of the organic EL display element, adhesion of foreign substances, cracks due to internal stress, etc., an organic light emitting material layer or an electrode is formed. There are cases where complete coverage is not possible. If the covering with the silicon nitride film is incomplete, moisture penetrates into the organic light-emitting material layer through the silicon nitride film.

As a method for preventing moisture from entering the organic light-emitting material layer, Patent Document 2 discloses a method of alternately depositing an inorganic material film and a resin film, and Patent Document 3 and Patent Document 4 disclose a method of depositing an inorganic material film and a resin film alternately on the inorganic material film. A method of forming a resin film is disclosed.

As a method of forming a resin film, there is a method of applying a sealant on a substrate using an inkjet method and then curing the sealant. By using such an inkjet coating method, a resin film can be formed at high speed and uniformly. However, when the encapsulant is made to have a low viscosity in order to make it suitable for application by the inkjet method, outgass is generated, or it cannot be ejected stably from the inkjet device, and the encapsulation becomes insufficient, making the resulting organic EL display element unreliable. There were problems such as becoming inferior.

Japanese Patent Publication No. 2000-223264 Japanese Patent Publication No. 2005-522891 Japanese Patent Publication No. 2001-307873 Japanese Patent Publication No. 2008-149710

The purpose of the present invention is to provide an encapsulant for an organic EL display element that can be easily applied by an inkjet method, has excellent low outgassing properties, and can produce an organic EL display element with excellent reliability. .

The present invention 1 is an encapsulant for an organic EL display element containing a polymerizable compound, wherein the polymerizable compound is a high boiling point polymerizable compound having a boiling point of 300°C or higher and a reactivity capable of reacting with the high boiling point polymerizable compound. It contains a low boiling point polymerizable compound having a functional group and a boiling point of less than 300° C., wherein the low boiling point polymerizable compound is selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds. A bag for organic EL display elements containing at least one type, the content of the low boiling point polymerizable compound in 100 parts by weight of the polymerizable compound is 1 part by weight or more and 20 parts by weight or less, and the haze of the cured product with a thickness of 10 μm is 1.0% or less. Jada.

The present invention 2 is an encapsulant for an organic EL display element containing a polymerizable compound, wherein the polymerizable compound is a high boiling point polymerizable compound with a boiling point of 300°C or higher and a reactivity capable of reacting with the high boiling point polymerizable compound. It contains a low boiling point polymerizable compound that has a functional group and a boiling point of less than 300°C, and the content of the low boiling point polymerizable compound in 100 parts by weight of the polymerizable compound is 1 part by weight or more and 20 parts by weight or less, and a thickness of 10 in advance. It is an encapsulant for organic EL display elements in which the outgassing amount of a cured product obtained by applying 1000 mJ/cm2 of 395 nm ultraviolet rays after application to a micrometer is less than 1000 ppm and the haze of a cured product with a thickness of 10 micrometers is 1.0% or less.

The present invention is described in detail below. In addition, matters common to the sealing agent for organic EL display elements of the present invention 1 and the sealing agent for organic EL display elements of the present invention 2 are described as "sealing agent for organic EL display elements of the present invention."

The present inventors have developed a sealant for organic EL display elements without using a polymerizable compound with a low boiling point as a polymerizable compound because volatilization deteriorates inkjet discharge properties and discharge stability or generates outgas. We considered producing it. However, the encapsulant for organic EL display elements produced without using a polymerizable compound with a low boiling point had a problem in that it had inferior wett diffusivity. Therefore, the present inventors studied blending a specific high boiling point polymerizable compound and a specific low boiling point polymerizable compound so that the content ratio was within a specific range. As a result, it was found that an encapsulant for organic EL display elements that can be easily applied by an inkjet method, has excellent low outgassing properties, and can be used to manufacture organic EL display elements with excellent reliability can be obtained. This led to completion of the present invention.

The encapsulant for organic EL display elements of the present invention contains a polymerizable compound.

The polymerizable compound has a high boiling point polymerizable compound having a boiling point of 300°C or higher (hereinafter also simply referred to as a “high boiling point polymerizable compound”) and a reactive functional group that can react with the high boiling point polymerizable compound, and further, It contains a low boiling point polymerizable compound (hereinafter also simply referred to as a “low boiling point polymerizable compound”) with a boiling point of less than 300°C. By using the high boiling point polymerizable compound and the low boiling point polymerizable compound in combination so that the contents described later are used, the encapsulant for organic EL display elements of the present invention has excellent inkjet discharge properties, discharge stability, and wet spreadability. do.

In addition, in this specification, the above-mentioned “boiling point” means the boiling point under 1 atm. In addition, for compounds with high boiling points that cannot be measured directly, the values are calculated using a boiling point conversion table using the boiling point under reduced pressure.

The high boiling point polymerizable compound has a boiling point of 300°C or higher. As described above, the high boiling point polymerizable compound having a boiling point of 300°C or higher and the low boiling point polymerizable compound having a boiling point of less than 300°C are used in combination in an amount described later, thereby producing the encapsulant for an organic EL display element of the present invention. becomes excellent in inkjet discharge properties, discharge stability, and wet spreadability.

From the viewpoint of low outgassing, the high boiling point polymerizable compound is preferably at least one selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds.

In addition, in this specification, the above-mentioned “(meth)acryl” means acrylic or methacryl. In addition, the above-mentioned “hydrosilylation-reactive compound” means a compound having a -SiH group, or a compound having a carbon-carbon double bond that can react with the -SiH group.

Specific examples of the high boiling point polymerizable compound include alkenyl group-containing organopolysiloxane, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and 1,4-butanediol. Diglycidyl ether, bisphenol F type epoxy resin, 2-ethylhexyloxetane, bis((3-ethyloxetan-3-yl)methyl)ether, dicyclopentenyloxyethyl acrylate, dipropylene glycol diacrylate salt, trimethylolpropane triacrylate, etc. are mentioned.

Examples of the alkenyl group-containing organopolysiloxane include vinyl-terminated polydimethylsiloxane, vinyl-terminated polymethylphenylsiloxane, and vinyl-terminated polydiphenylsiloxane.

As the high boiling point polymerizable compound, bis((3-ethyloxetan-3-yl)methyl)ether is particularly preferable.

The alkenyl group-containing organopolysiloxane can be produced by subjecting disiloxane containing terminal alkenyl groups and cyclic organopolysiloxane to an equilibrium reaction in the presence of an alkali catalyst.

The cyclic organopolysiloxane may be a compound containing an alkenyl group in the side chain, such as 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane.

The low boiling point polymerizable compound has a boiling point of less than 300°C. As described above, the high boiling point polymerizable compound having a boiling point of 300°C or higher and the low boiling point polymerizable compound having a boiling point of less than 300°C are used in combination in an amount described later, thereby producing the encapsulant for an organic EL display element of the present invention. becomes excellent in inkjet discharge properties, discharge stability, and wet spreadability. The preferred upper limit of the boiling point of the low boiling point polymerizable compound is 290°C.

In addition, from the viewpoint of low outgassing properties, etc., the lower boiling point of the low-boiling polymerizable compound is preferably 150°C, more preferably 200°C, and still more preferably 240°C.

The low boiling point polymerizable compound has a reactive functional group that can react with the high boiling point polymerizable compound. The reactive functional group varies depending on the type of the high boiling point polymerizable compound, but includes, for example, an epoxy group, oxetanyl group, (meth)acryloyl group, -SiH group, and a carbon-carbon double that can react with -SiH group. A group containing a bond, etc. can be mentioned.

In addition, in this specification, the above-mentioned “(meth)acryloyl” means acryloyl or methacryloyl.

In the encapsulant for organic EL display elements of the present invention 1, the low boiling point polymerizable compound is at least one selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds. When the low boiling point polymerizable compound is at least one selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds, the resulting sealing agent for organic EL display elements has excellent low outgassing properties. It becomes a thing.

In the encapsulant for organic EL display elements of the present invention 2, the low boiling point polymerizable compound is preferably at least one selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds. do. When the low boiling point polymerizable compound is at least one selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds, the amount of outgassing generated from the cured product of the sealant for organic EL display elements obtained It becomes easy to keep within the range described later.

Specific examples of the low boiling point polymerizable compound include 1,7-octadiene diepoxide (boiling point 243°C), neopentyl glycol diglycidyl ether (boiling point 273°C), and ethylene glycol diglycidyl. Ether (boiling point 269°C), isobornyl acrylate (boiling point 250°C), 1,6-hexanediol diacrylate (boiling point 295°C), 3-ethyl-3-hydroxymethyloxetane (boiling point 298°C), 3-ethyl-3-oxetanemethanol (boiling point 241°C), 3-allyloxyoxetane (boiling point 146°C), 1,3-butadiene diepoxide (boiling point 153°C), methylhydrogenpolysiloxane (boiling point 142°C) etc. can be mentioned. Among them, 1,7-octadiene diepoxide, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, isobornyl acrylate, 1,6-hexanediol diacrylate, 3-ethyl- At least one selected from the group consisting of 3-hydroxymethyloxetane and 3-ethyl-3-oxetanemethanol is preferred.

The lower limit of the content of the low boiling point polymerizable compound in 100 parts by weight of the polymerizable compound is 1 part by weight, and the upper limit is 20 parts by weight. When the content of the low boiling point polymerizable compound is within this range, the encapsulant for organic EL display elements of the present invention becomes excellent in inkjet discharge properties, discharge stability, and wet spreadability. The preferable lower limit of the content of the low boiling point polymerizable compound is 5 parts by weight, and the preferable upper limit is 10 parts by weight.

When using the cyclic ether compound or the (meth)acrylic compound as the polymerizable compound, it is preferable that the sealing agent for organic EL display elements of the present invention contains a polymerization initiator.

As the polymerization initiator, a photocationic polymerization initiator, a thermal cationic polymerization initiator, a photoradical polymerization initiator, or a thermal radical polymerization initiator is preferably used, depending on the type of the polymerizable compound used.

The photocationic polymerization initiator is not particularly limited as long as it generates protonic acid or Lewis acid by light irradiation, and may be of an ionic acid-generating type or a nonionic photoacid-generating type.

As an anion part of the ionic acid-generating photocationic polymerization initiator, for example, an anion part is BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , or (BX ₄ ) ^- (however, represents a phenyl group substituted with at least two or more fluorine or trifluoromethyl groups), and the like.

Examples of the ionic acid-generating photocationic polymerization initiator include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, and (2,4-cyclopentadiene) having the anion moiety. -1-yl)((1-methylethyl)benzene)-Fe salt, etc. can be mentioned.

Examples of the aromatic sulfonium salt include bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluorophosphate and bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluorophosphate. Roantimonate, 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 tetra Fluoroborate, diphenyl-4-(phenylthio)phenylsulfonium tetrakis(pentafluorophenyl)borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium Tetrafluoroborate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, 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, tris (4- (4-acetylphenyl) thiophenyl) sulfonium tetrakis (pentafluorophenyl) borate, etc. .

Examples of the aromatic iodonium salt include diphenyl iodonium hexafluorophosphate, diphenyl iodonium hexafluoroantimonate, diphenyl iodonium tetrafluoroborate, and diphenyl iodonium tetrakis (pentafluorocarbonate). Phenyl)borate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium hexafluoroantimonate )Iodium tetrakis(pentafluorophenyl)borate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluorophosphate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluorophosphate Roantimonate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrafluoroborate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrakis(pentafluorophenyl)borate, etc. can be mentioned.

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

Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, and 1-benzyl-2-cyano. Pyridinium tetrafluoroborate, 1-benzyl-2-cyanopyridinium tetrakis(pentafluorophenyl)borate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluorophosphate, 1-(naph Tylmethyl)-2-cyanopyridinium hexafluoroantimonate, 1-(naphthylmethyl)-2-cyanopyridinium tetrafluoroborate, 1-(naphthylmethyl)-2-cyanopyridinium Tetrakis (pentafluorophenyl) borate, etc. can be mentioned.

The (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salt includes, for example, (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, (2,4-cyclopentadien-1-yl)((1-methylethyl )Benzene)-Fe (II) tetrakis(pentafluorophenyl)borate, etc.

Examples of the nonionic photoacid generating type photocation polymerization initiator include nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenol sulfonic acid ester, diazonaphthoquinone, N-hydroxyimide sulfonate, etc. .

Among the above-mentioned photocationic polymerization initiators, commercially available ones include, for example, a photocationic polymerization initiator manufactured by Midori Chemical Co., Ltd., a photocationic polymerization initiator manufactured by Union Carbide, a photocationic polymerization initiator manufactured by ADEKA Co., Ltd., and a photocationic polymerization initiator manufactured by 3M Co., Ltd. A photocationic polymerization initiator manufactured by BASF, a photocationic polymerization initiator manufactured by Rhodia, etc. may be mentioned.

Examples of the photocationic polymerization initiator manufactured by Midori Chemical Co., Ltd. include DTS-200.

Examples of the photocationic polymerization initiator manufactured by Union Carbide include UVI6990 and UVI6974.

Examples of the photocationic polymerization initiator manufactured by ADEKA include SP-150 and SP-170.

Examples of the photocationic polymerization initiator manufactured by 3M include FC-508 and FC-512.

Examples of the photocationic polymerization initiator manufactured by BASF include IRGACURE261 and IRGACURE290.

Examples of the photocationic polymerization initiator manufactured by Rhodia include PI2074 and the like.

In the above thermal cationic polymerization initiator, the anion moiety is BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , or (BX ₄ ) ^- (provided that X is substituted with at least two or more fluorine or trifluoromethyl groups sulfonium salts, phosphonium salts, ammonium salts, etc., which are composed of a phenyl group. Among them, sulfonium salts and ammonium salts are preferable.

Examples of the sulfonium salt include triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, and the like.

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

Examples of the ammonium salt include dimethylphenyl (4-methoxybenzyl) ammonium hexafluorophosphate, dimethylphenyl (4-methoxybenzyl) ammonium hexafluoroantimonate, and dimethylphenyl (4-methoxybenzyl). Ammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(4-methylbenzyl)ammonium hexafluorophosphate, dimethylphenyl(4-methylbenzyl)ammonium hexafluoroantimonate, dimethylphenyl(4-methylbenzyl)ammonium Hexafluorotetrakis(pentafluorophenyl)borate, methylphenyldibenzylammonium hexafluorophosphate, methylphenyldibenzylammonium hexafluoroantimonate, methylphenyldibenzylammoniumtetrakis(pentafluorophenyl)borate, phenyltribenzyl Ammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(3,4-dimethylbenzyl)ammonium tetrakis(pentafluorophenyl)borate, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-diethyl-N-benzylaniliniumtetrafluoroborate, N,N-dimethyl-N-benzylpyridiniumhexafluoroantimonate, N,N-diethyl-N-benzylpyridiniumtrifluoro Methanesulfonic acid, etc. can be mentioned.

Examples of commercially available thermal cationic polymerization initiators include a thermal cationic polymerization initiator manufactured by Sanshin Chemical Industries, Ltd., and a thermal cationic polymerization initiator manufactured by King Industries.

Examples of the thermal cationic polymerization initiator manufactured by Sanshin Chemical Industries, Ltd. include San-Aid SI-60, San-Aid SI-80, San-Aid SI-B3, San-Aid SI-B3A, San-Aid SI-B4, etc. You can.

Examples of the thermal cation polymerization initiator manufactured by King Industries include CXC1612 and CXC1821.

Examples of the photo radical polymerization initiator include benzophenone-based compounds, acetophenone-based compounds, acylphosphine oxide-based compounds, titanocene-based compounds, oxime ester-based compounds, benzoin ether-based compounds, benzyl, and thioxanthone-based compounds. Compounds, etc. can be mentioned.

Among the photo radical polymerization initiators, commercially available ones include, for example, IRGACURE184, IRGACURE369, IRGACURE379, IRGACURE651, IRGACURE819, IRGACURE907, IRGACURE2959, IRGACURE OXE01, IRGACURE TPO (all manufactured by BASF), benzoin methyl ether, and benzoin ethyl. Ether, benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.), etc. can be mentioned.

Examples of the thermal radical polymerization initiator include those made of azo compounds, organic peroxides, etc.

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.

Among the 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.). I can hear it.

The content of the polymerization initiator has a preferable lower limit of 0.01 parts by weight and a preferable upper limit of 10 parts by weight based on 100 parts by weight of the polymerizable compound. When the content of the polymerization initiator is 0.01 part by weight or more, the obtained sealing agent for organic EL display elements becomes more excellent in curability. When the content of the polymerization initiator is 10 parts by weight or less, the curing reaction of the resulting encapsulant for organic EL display elements does not become too fast, workability becomes more excellent, and the cured product can be made more uniform. The more preferable lower limit of the content of the polymerization initiator is 0.05 parts by weight, and the more preferable upper limit is 5 parts by weight.

The encapsulant for organic EL display elements of the present invention may contain a sensitizer. The sensitizer has a role in further improving the polymerization initiation efficiency of the polymerization initiator and further promoting the curing reaction of the encapsulant for organic EL display elements of the present invention.

Examples of the sensitizer include thioxanthone compounds, 2,2-dimethoxy-1,2-diphenylethan-1-one, benzophenone, 2,4-dichlorobenzophenone, and o-benzoylmethylbenzoate. , 4,4'-bis(dimethylamino)benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, etc.

Examples of the thioxanthone compound include 2,4-diethylthioxanthone.

The content of the sensitizer has a preferable lower limit of 0.01 parts by weight and a preferable upper limit of 3 parts by weight with respect to 100 parts by weight of the polymerizable compound. When the content of the sensitizer is 0.01 part by weight or more, the sensitizing effect is more exhibited. When the content of the sensitizer is 3 parts by weight or less, it is possible to harden even the deep portion without causing excessive absorption. The more preferable lower limit of the content of the sensitizer is 0.1 part by weight, and the more preferable upper limit is 1 part by weight.

When using the hydrosilylation reactive compound as the polymerizable compound, it is preferable that the encapsulant for organic EL display elements of the present invention contains a hydrosilylation reaction catalyst.

Examples of the hydrosilylation reaction catalyst include (methylcyclopentadienyl)trimethyl platinum, bis(2,4-pentanedionate)platinum (II), and the like. Among them, (methylcyclopentadienyl)trimethyl platinum is preferable.

The content of the hydrosilylation reaction catalyst has a preferable lower limit of 0.0005 parts by weight and a preferable upper limit of 0.010 parts by weight based on 100 parts by weight of the polymerizable compound. When the content of the hydrosilylation reaction catalyst is 0.0005 parts by weight or more, the resulting encapsulant for organic EL display elements has better curability. When the content of the hydrosilylation reaction catalyst is 0.010 parts by weight or less, the curing reaction of the obtained encapsulant for organic EL display elements does not become too fast, workability is improved, and the cured product can be made more uniform. there is. A more preferable lower limit of the content of the hydrosilylation reaction catalyst is 0.001 parts by weight, and a more preferable upper limit is 0.002 parts by weight.

The encapsulant for organic EL display elements of the present invention may contain a silane coupling agent. The silane coupling agent has a role in improving the adhesion between the encapsulant for organic EL display elements of the present invention and the substrate.

Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-isocyanatepropyltrimethoxysilane, etc. can be mentioned. These silane coupling agents may be used individually, or two or more types may be used together.

The content of the silane coupling agent has a preferable lower limit of 0.1 parts by weight and a preferable upper limit of 10 parts by weight based on 100 parts by weight of the polymerizable compound. When the content of the silane coupling agent is within this range, the effect of improving adhesion is more excellent while suppressing bleeding out of the excess silane coupling agent. The more preferable lower limit of the content of the silane coupling agent is 0.5 parts by weight, and the more preferable upper limit is 5 parts by weight.

The encapsulant for organic EL display elements of the present invention may further contain a surface modifier within a range that does not impair the purpose of the present invention. By containing the surface modifier, flatness of the coating film can be imparted to the encapsulant for organic EL display elements of the present invention.

Examples of the surface modifier include surfactants and leveling agents.

Examples of the surface modifier include silicone-based and fluorine-based ones.

Examples of commercially available surface modifiers include BYK-340, BYK-345 (all manufactured by Big Chemie Japan), Suplon S-611 (manufactured by AGC Semi Chemicals), and the like.

The encapsulant for organic EL display elements of the present invention may contain a solvent for purposes such as viscosity adjustment, but there is a risk that the remaining solvent may cause problems such as deterioration of the organic luminescent material layer or generation of outgassing. Therefore, it is preferable that the solvent is not contained or that the solvent content is 0.05% by weight or less.

Additionally, the encapsulant for organic EL display elements of the present invention may contain various known additives, such as reinforcing agents, softeners, plasticizers, viscosity modifiers, ultraviolet absorbers, and antioxidants, as needed.

The method for producing the encapsulant for organic EL display elements of the present invention includes, for example, using a mixer such as a homodisper, homomixer, universal mixer, planetary mixer, kneader, or three roll, A method of mixing the compound, a polymerization initiator, and additives such as a silane coupling agent added as needed, etc. are included.

The encapsulant for organic EL display elements of the present invention has a preferable lower limit of viscosity at 25°C of 3 mPa·s and a preferable upper limit of 20 mPa·s. When the viscosity is within this range, inkjet discharge properties, discharge stability, and wet spreadability become more excellent. The more preferable lower limit of the viscosity is 5 mPa·s, and the more preferable upper limit is 15 mPa·s.

In addition, in this specification, the viscosity means a value measured under the condition of 100 rpm using an E-type viscometer.

The sealing agent for organic EL display elements of the present invention has a preferable lower limit of surface tension at 25°C of 15 mN/m and a preferable upper limit of 35 mN/m. When the surface tension is within this range, inkjet discharge properties, discharge stability, and wet spreadability become more excellent. The more preferable lower limit of the surface tension is 20 mN/m, the more preferable upper limit is 30 mN/m, the more preferable lower limit is 22 mN/m, and the more preferable upper limit is 28 mN/m.

In addition, in this specification, the surface tension means a value measured by the Wilhelmy method using a dynamic wettability tester.

The upper limit of the haze of the encapsulant for organic EL display elements of the present invention of a cured product with a thickness of 10 μm is 1.0%. When the haze is 1.0% or less, the resulting organic EL display element has excellent optical properties. The preferable upper limit of the haze is 0.5%, and the more preferable upper limit is 0.3%. The lower the haze, the better. There is no particular preferable lower limit, but in practice, it is 0.01% or more.

Moreover, the sealing agent for organic EL display elements of this invention has a preferable minimum of the total light transmittance of the light in the wavelength of 380-800 nm of hardened|cured material of 80%. When the total light transmittance is 80% or more, the resulting organic EL display element has superior optical properties. A more preferable lower limit of the total light transmittance is 85%.

The haze value can be within a desired range by adjusting the type and mixing amount of the high boiling point polymerizable compound, the low boiling point polymerizable compound, the polymerization initiator, and the sensitizer. In particular, taking into consideration the compatibility of the high-boiling-point polymerizable compound and the low-boiling-point polymerizable compound, it becomes easy to adjust the combination and mixing amount to keep it within the desired range. As a result, it is possible to obtain an encapsulant for organic EL display elements that has superior optical properties than a composition simply containing a high boiling point polymerizable compound and a low boiling point polymerizable compound.

In addition, the haze and the total light transmittance can be measured using, for example, a spectrometer such as AUTOMATIC HAZE METER MODEL TC-III DPK (manufactured by Tokyo Electronics Co., Ltd.). In addition, the cured product used to measure the haze, the total light transmittance, and the moisture permeability and moisture content described later is, for example, obtained by irradiating 1000 mJ/cm2 of ultraviolet rays with a wavelength of 395 nm using a light source such as an LED lamp. You can.

The encapsulant for organic EL display elements of the present invention 1 is preferably coated to a thickness of 10 μm in advance and then irradiated with 395 nm ultraviolet rays at 1000 mJ/cm2, so that the resulting cured product preferably has an outgassing amount of less than 1000 ppm. When the amount of outgassing is less than 1000 ppm, the resulting organic EL display element has better reliability. A more preferable upper limit of the amount of outgassing is 500 ppm, and a more preferable upper limit is 100 ppm.

The smaller the amount of outgas generated, the better. There is no particular lower limit, but in practice, it is 5 ppm or more.

In addition, the amount of outgassing can be measured using a gas chromatograph mass spectrometer (for example, JMS-Q1050 (manufactured by Nippon Electronics)).

The encapsulant for organic EL display elements of the present invention 2 is coated in advance to a thickness of 10 µm and then irradiated with 395 nm ultraviolet rays at 1000 mJ/cm2, and the resulting cured product has an outgassing amount of less than 1000 ppm. When the amount of outgassing is less than 1000 ppm, the resulting organic EL display element has excellent reliability. The preferable upper limit of the amount of outgassing is 500 ppm, and a more preferable upper limit is 100 ppm.

The smaller the amount of outgas generated, the better. There is no particular lower limit, but in practice, it is 5 ppm or more.

The encapsulant for organic EL display elements of the present invention has a moisture permeability of 100 g/m2 or less at a thickness of 100 ㎛ measured by exposing the cured product to an environment of 85°C and 85%RH for 24 hours in accordance with JIS Z 0208. desirable. When the moisture permeability is 100 g/m 2 or less, the effect of preventing deterioration of the organic luminescent material layer due to moisture in the cured material becomes more excellent, and the resulting organic EL display element becomes more reliable.

When the encapsulant for organic EL display elements of the present invention exposes the cured product to an environment of 85°C and 85%RH for 24 hours, the moisture content of the cured product is preferably less than 0.5%. When the water content of the cured product is less than 0.5%, the effect of preventing deterioration of the organic luminescent material layer due to moisture in the cured product becomes more excellent, and the resulting organic EL display element becomes more reliable. A more preferable upper limit of the moisture content of the cured product is 0.3%.

Examples of the method for measuring the water content include a method of determining the moisture content by the Karl Fischer method based on JIS K 7251, and a method of determining the weight increment after absorption based on JIS K 7209-2.

The encapsulant for organic EL display elements of the present invention is preferably used for application by an inkjet method.

A method of manufacturing an organic EL display element using the encapsulant for an organic EL display element of the present invention includes, for example, a process of applying the encapsulant for an organic EL display element of the present invention to a substrate by an inkjet method; , a method having a step of curing the applied encapsulant for organic EL display elements by light irradiation and/or heating, etc.

In the step of applying the sealant for organic EL display elements of the present invention to a substrate, the sealant for organic EL display elements of the present invention may be applied to the entire surface of the substrate or to a part of the substrate. The shape of the sealing portion of the encapsulant for organic EL display elements of the present invention formed by application is not particularly limited as long as it is a shape that can protect the laminate having the organic luminescent material layer from external air, and the laminate is completely covered. The pattern may be formed in a shape such that a closed pattern is formed on the periphery of the laminate, or a pattern in which some openings are formed may be formed on the periphery of the laminate.

When the encapsulant for organic EL display elements of the present invention is cured by light irradiation, the encapsulant for organic EL display elements of the present invention has a wavelength of 300 nm or more and 400 nm or less and a wavelength of 300 mJ/cm2 or more and 3000 mJ/cm2 or less. It can be preferably cured by irradiating light with an accumulated amount of light.

Light sources used for the above light irradiation include, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, an excimer laser, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, a sodium lamp, and a halogen lamp. , xenon lamps, LED lamps, fluorescent lamps, solar lights, electron beam irradiation devices, etc. These light sources may be used individually, or two or more types may be used together.

These light sources are appropriately selected according to the absorption wavelength of the radical photopolymerization initiator or the photocationic polymerization initiator.

Examples of means for irradiating light to the encapsulant for organic EL display elements of the present invention include simultaneous irradiation from various light sources, sequential irradiation with a time difference, combined irradiation of simultaneous irradiation and sequential irradiation, etc., which irradiation You may use any means.

The cured product obtained by the process of curing the encapsulant for organic EL display elements by light irradiation and/or heating may be further coated with an inorganic material film.

As the inorganic material constituting the inorganic material film, conventionally known materials can be used, and examples include silicon nitride (SiN _x ) and silicon oxide (SiO _x ). The inorganic material film may be composed of one layer, or may be a laminate of multiple types of layers. In addition, the above-described inorganic material film and the resin film made of the encapsulant for organic EL display elements of the present invention may be alternately covered to cover the above-described laminate.

The method of manufacturing the organic EL display element includes a step of bonding a substrate coated with the encapsulant for an organic EL display element of the present invention (hereinafter also referred to as “one substrate”) and the other substrate. You can stay.

The substrate to which the encapsulant for organic EL display elements of the present invention is applied (hereinafter also referred to as “one substrate”) may be a substrate on which a laminate having an organic luminescent material layer is formed, or a substrate on which the laminate is not formed. It's okay.

When one of the substrates is a substrate on which the laminate is not formed, the encapsulant for an organic EL display element of the present invention is applied to one of the substrates so that the laminate can be protected from external air when the other substrate is bonded together. Just apply. That is, a bag with a closed pattern is applied entirely to the location that will be the location of the laminate when the other substrate is bonded together, or the location that will be the location of the laminate when the other substrate is bonded is completely enclosed. You can form a jebu.

The process of curing the encapsulant for organic EL display elements by light irradiation and/or heating may be carried out before the process of bonding the one base material and the other base material, and the one base material and the other base material may be bonded together. It may be carried out after the bonding process.

When the step of curing the encapsulant for an organic EL display device by light irradiation and/or heating is performed before the step of bonding one of the substrates to the other substrate, the encapsulant for an organic EL display device of the present invention It is preferable that the pot life after light irradiation and/or heating until the curing reaction proceeds and adhesion becomes impossible is 1 minute or more. When the pot life is 1 minute or more, curing does not proceed excessively before bonding one of the substrates to the other substrate, and higher adhesive strength can be obtained.

In the step of bonding the one substrate and the other substrate, the method of bonding the one substrate and the other substrate is not particularly limited, but bonding in a reduced pressure atmosphere is preferable.

The lower limit of the vacuum degree in the reduced pressure atmosphere is 0.01 kPa, and the upper limit is 10 kPa. Since the degree of vacuum in the reduced pressure atmosphere is within this range, the present invention is used to bond one of the base materials to the other base material without spending a long time to achieve a vacuum state due to the airtightness of the vacuum device or the ability of the vacuum pump. Air bubbles in the encapsulant for organic EL display elements can be removed more efficiently.

According to the present invention, it is possible to provide a sealant for an organic EL display element that can be easily applied by an inkjet method, has excellent low outgassing properties, and can obtain an organic EL display element with excellent reliability.

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

(Examples 1 to 8, Comparative Examples 1 to 7)

According to the mixing ratios shown in Tables 1 to 3, each material was uniformly stirred and mixed at a stirring speed of 3000 rpm using a Homo Disper type stirring mixer (“Homo Disper L Type” manufactured by Primix Co., Ltd.). Encapsulants for each organic EL display element of Examples 1 to 8 and Comparative Examples 1 to 7 were produced.

For each of the organic EL display element encapsulants obtained in the examples and comparative examples, the viscosity was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., “VISCOMETER TV-22”) under conditions of 25°C and 100 rpm, And the surface tension measured at 25°C with a dynamic wettability tester (“WET-6100 type” manufactured by Resca Corporation) is shown in Tables 1 to 3.

In addition, each of the encapsulants for organic EL display elements obtained in the examples and comparative examples was applied in advance to a thickness of 10 ㎛ on a glass substrate, and then irradiated with 1000 mJ/cm2 of ultraviolet rays at 395 nm using a UV-LED to form a cured product. got it 20 mg of the obtained cured product was weighed and sealed in a vial bottle. This vial was heated at 100°C for 30 minutes, and the vaporized component in the vial was measured as the amount of outgas generated using a gas chromatograph mass spectrometer (JMS-Q1050, manufactured by Nippon Electronics Co., Ltd.). The results are shown in Tables 1 to 3.

In addition, after applying each of the encapsulants for organic EL display elements obtained in the examples and comparative examples onto a glass substrate, 1000 mJ/cm2 of ultraviolet rays of 395 nm were irradiated using a UV-LED to form a cured product with a thickness of 10 μm. got it For the obtained cured product, haze and total light transmittance of light at a wavelength of 380 to 800 nm were measured using a spectrometer. As the spectrometer, AUTOMATIC HAZE METER MODEL TC-III DPK (manufactured by Tokyo Densoku Co., Ltd.) was used.

In addition, for “Celoxide 2021P” and two types of “alkenyl group-containing organopolysiloxane” in the table, it was confirmed that the boiling point at 1 atm was 300°C or higher, but the accurate boiling point could not be measured even under reduced pressure. Therefore, the specific value of the boiling point was not indicated and was stated as “300°C or higher.”

＜Evaluation＞

The following evaluation was performed on each of the encapsulants for organic EL display elements obtained in Examples and Comparative Examples. The results are shown in Tables 1 to 3.

(1) Inkjet applicability

(1-1) Inkjet discharge properties

Alkaline-free glass obtained by alkali washing each of the encapsulants for organic EL display elements obtained in the examples and comparative examples in a droplet volume of 30 picoliters using an inkjet ejection device (“Nano Printer 500” manufactured by Microjet). (“AN100” manufactured by Asahi Glass Co., Ltd.). Cases where discharge was possible without discharge defects and clean discharge were marked as “○”; cases where 80% or more of the discharge was possible but discharge defects of less than 20% occurred as “△”; cases where discharge defects of 20% or more occurred were marked as “×” Inkjet ejection properties were evaluated.

(1-2) Discharge stability

Alkaline-free glass obtained by alkali washing each of the encapsulants for organic EL display elements obtained in the examples and comparative examples in a droplet volume of 80 picoliters using an inkjet ejection device (“Nano Printer 500” manufactured by Microjet). 1000 drops were applied on (“AN100” manufactured by Asahi Glass Co., Ltd.) at a pitch of 500 μm at a speed of 5 m/sec. After application, it was left at 25°C for 10 minutes, application was performed again under the same conditions as above, and the state of the droplets on the glass substrate after the second application was observed.

“○” indicates that the number of droplets that could not be applied was 0, “△” indicates that the number of droplets that could not be applied was 1 to 20, and “△” indicates that the number of droplets that could not be applied was 20 or more. ×」 to evaluate the discharge stability.

(1-3) Wet spreadability

Alkaline-free glass obtained by alkali washing each of the encapsulants for organic EL display elements obtained in the examples and comparative examples in a droplet volume of 30 picoliters using an inkjet ejection device (“Nano Printer 500” manufactured by Microjet). 1000 drops were applied on (“AN100” manufactured by Asahi Glass Co., Ltd.) at a pitch of 500 μm at a speed of 5 m/sec. After application, it was left at 25°C for 10 minutes, and the diameter of the droplet on the alkali-free glass was measured.

The case where the droplet diameter was 150 ㎛ or more was designated as “○”, the case where the droplet diameter was 50 ㎛ or more but less than 150 ㎛ was designated as “△”, and the case where the droplet diameter was less than 50 ㎛ was designated as “×” to determine the wett spreadability. evaluated.

(2) Reliability of organic EL display elements

(2-1) Fabrication of a substrate on which a laminate having an organic light-emitting material layer is disposed

A substrate was prepared by forming an ITO electrode to a thickness of 1000 Å on a glass substrate (length 25 mm, width 25 mm, thickness 0.7 mm). The substrate was ultrasonically cleaned with acetone, aqueous alkaline solution, ion-exchanged water, and isopropyl alcohol for 15 minutes each, then cleaned with boiled isopropyl alcohol for 10 minutes, and further washed with UV-ozone cleaner (Nippon Laser Electronics). The previous treatment was performed with (manufactured by “NL-UV253”).

Next, this substrate was fixed to the substrate folder of the vacuum evaporation device, and 200 mg of N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (α-NPD) was added to the unglazed crucible. 200 mg of tris(8-quinolinolato)aluminum (Alq ₃ ) was placed in another unglazed crucible, and the pressure inside the vacuum chamber was reduced to 1×10 ^-4 Pa. Afterwards, the crucible containing α-NPD was heated, α-NPD was deposited on the substrate at a deposition rate of 15 Å/s, and a hole transport layer with a film thickness of 600 Å was formed. Next, the crucible containing Alq ₃ was heated to form an organic light-emitting material layer with a thickness of 600 Å at a deposition rate of 15 Å/s. Thereafter, the substrate on which the hole transport layer and the organic light-emitting material layer were formed was transferred to another vacuum evaporation device, and 200 mg of lithium fluoride was added to a tungsten resistance heating boat in this vacuum evaporation device, and 1.0 g of aluminum wire was added to the other tungsten boat. I put it in. Afterwards, the pressure inside the evaporator of the vacuum evaporation device was reduced to 2 × 10 ^-4 Pa to form a 5 Å film of lithium fluoride at a deposition rate of 0.2 Å/s, and then a 1000 Å film of aluminum was formed at a rate of 20 Å/s. The inside of the evaporator was returned to normal pressure with nitrogen, and the substrate on which the laminate having a 10 mm × 10 mm organic light-emitting material layer was disposed was taken out.

(2-2) Covering with inorganic material film A

A mask having an opening of 13 mm x 13 mm was installed to cover the entire substrate on which the obtained laminate was placed, and an inorganic material film A was formed by the plasma CVD method.

The plasma CVD method uses SiH ₄ gas and nitrogen gas as raw material gases, the respective flow rates are set to 10 sccm for SiH 4 gas and 200 sccm for nitrogen gas, the RF power is set to 10 W (frequency 2.45 GHz), and the temperature inside the chamber is set to 10 sccm for SiH ₄ gas and 200 sccm for nitrogen gas. It was carried out at 100°C and the pressure inside the chamber was 0.9 Torr.

The thickness of the formed inorganic material film A was about 1 μm.

(2-3) Formation of resin protective film

With respect to the obtained substrate, each of the encapsulants for organic EL display elements obtained in the examples and comparative examples was applied in a pattern to the substrate using an inkjet ejection device (“Nano Printer 500” manufactured by Microjet Corporation).

After that, the encapsulant for organic EL display elements was cured by irradiating 1000 mJ/cm2 of ultraviolet rays with a wavelength of 395 nm using an LED lamp to form a resin protective film.

(2-4) Covering with inorganic material film B

After forming the resin protective film, a mask with an opening of 12 mm x 12 mm was installed to cover the entire resin protective film, and an inorganic material film B was formed by plasma CVD to obtain an organic EL display element.

The plasma CVD method was carried out under the same conditions as in “(2-2) Coating with inorganic material film A” above.

The thickness of the formed inorganic material film B was about 1 μm.

(2-5) Light emission state of organic EL display element

The obtained organic EL display element was exposed to an environment with a temperature of 85°C and a humidity of 85% for 100 hours, and then a voltage of 3 V was applied to inspect the luminescence state of the organic EL display element (the presence or absence of dark spots and extinction around the pixel) with the naked eye. was observed. “○” indicates uniform light emission without dark spots or ambient extinction, “△” indicates that there are no dark spots or ambient extinction, but a slight decrease in luminance is confirmed, and “×” indicates cases where dark spots or peripheral extinction are confirmed. 」 to evaluate the reliability of the organic EL display device.

According to the present invention, it is possible to provide a sealant for an organic EL display element that can be easily applied by an inkjet method, has excellent low outgassing properties, and can obtain an organic EL display element with excellent reliability.

Claims (7)

An encapsulant for organic EL display elements containing a polymerizable compound,
The polymerizable compound contains a high boiling point polymerizable compound having a boiling point of 300°C or higher, a low boiling point polymerizable compound having a reactive functional group capable of reacting with the high boiling point polymerizable compound, and a boiling point of less than 300°C,
The low boiling point polymerizable compound is at least one selected from the group consisting of cyclic ether compounds, (meth)acrylic compounds, and hydrosilylation reactive compounds,
The content of the low boiling point polymerizable compound in 100 parts by weight of the polymerizable compound is 1 part by weight or more and 20 parts by weight or less,
The viscosity at 25°C is 3 mPa·s or more and 20 mPa·s or less,
The solvent content is 0.05% by weight or less,
A sealant for organic EL display elements, characterized in that the haze of the cured product with a thickness of 10 μm is 1.0% or less. An encapsulant for organic EL display elements containing a polymerizable compound,
The polymerizable compound contains a high boiling point polymerizable compound having a boiling point of 300°C or higher, a low boiling point polymerizable compound having a reactive functional group capable of reacting with the high boiling point polymerizable compound, and a boiling point of less than 300°C,
The content of the low boiling point polymerizable compound in 100 parts by weight of the polymerizable compound is 1 part by weight or more and 20 parts by weight or less,
The viscosity at 25°C is 3 mPa·s or more and 20 mPa·s or less,
The solvent content is 0.05% by weight or less,
The outgassing amount of the cured product obtained by applying it to a thickness of 10 ㎛ in advance and then irradiating 1000 mJ/cm2 of 395 nm ultraviolet rays is less than 1000 ppm,
A sealing agent for organic EL display elements, characterized in that the haze of the cured product with a thickness of 10 μm is 1.0% or less. The method of claim 1 or 2,
An encapsulant for an organic EL display element, characterized in that the low boiling point polymerizable compound has a boiling point of 150°C or higher. The method of claim 1 or 2,
Low boiling point polymerizable compounds include 1,7-octadiene diepoxide, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, isobornyl acrylate, 1,6-hexanediol diacrylate, 3 - An encapsulant for an organic EL display element, characterized in that it is at least one member selected from the group consisting of ethyl-3-hydroxymethyloxetane and 3-ethyl-3-oxetane methanol. delete The method of claim 1 or 2,
A sealing agent for organic EL display elements, characterized in that the surface tension at 25°C is 15 mN/m or more and 35 mN/m or less. The method of claim 1 or 2,
An encapsulant for organic EL display elements, characterized in that it is used for application by the inkjet method.