KR102641589B1 - Sealing agent for organic electroluminescence display element - Google Patents

Abstract

The purpose of the present invention is to provide an encapsulant for an organic electroluminescence display element that has excellent barrier properties and toughness of the cured product.
The present invention contains a cationically polymerizable compound, olefinic rubber particles, a photocationic polymerization initiator, and an alkaline earth metal-based and/or magnesium-based water absorbent filler, wherein the olefinic rubber particles have a core-shell structure. It is an encapsulant for organic electroluminescence display elements.

Description

Encapsulant for organic electroluminescence display elements {SEALING AGENT FOR ORGANIC ELECTROLUMINESCENCE DISPLAY ELEMENT}

The present invention relates to an encapsulant for an organic electroluminescent display device having excellent barrier properties and toughness of the cured product.

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 the organic light-emitting material layer receives light from one electrode. As electrons are injected and holes are injected from the other electrode, electrons and holes combine within the organic light-emitting material layer to emit light. In this way, since organic EL display elements emit self-luminescence, they have good visibility compared to liquid crystal display elements that require a backlight, can be made thinner, and can be driven at low direct current voltage. It has the advantage of

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. As a method of blocking the organic light-emitting material layer or electrode from the atmosphere, sealing the organic EL display element using a sealing agent has been implemented (for example, patent document 1). When sealing an organic EL display element with a sealing agent, an inorganic film called a passivation film is usually formed on the laminate having the organic light emitting material layer in order to sufficiently suppress the penetration of moisture, oxygen, etc., and the inorganic film is sealed. The zero bagging method is being used.

Recently, instead of the bottom emission type organic EL display element, which extracts the light emitted from the organic light emitting material layer from the surface of the substrate on which the light emitting element is formed, the top emission type organic EL display element extracts light from the top side of the organic light emitting layer. EL display elements are attracting attention. This method has the advantage of having a long lifespan in that it has a high aperture ratio and is driven at a low voltage. In such a top emission type organic EL display element, since the upper surface side of the light emitting layer needs to be transparent, the upper surface side of the light emitting element is sealed by laminating a transparent moisture-proof substrate such as glass through a transparent encapsulating resin (e.g. For example, patent document 2).

However, in such a top-emission organic EL display device, there is no space for arranging a desiccant so as not to block the light extraction direction, so there is a problem that a sufficient moisture-proof effect cannot be obtained and the lifespan is shortened.

Japanese Patent Publication No. 2007-115692 Japanese Patent Publication No. 2009-051980

The purpose of the present invention is to provide an encapsulant for an organic electroluminescence display element that has excellent barrier properties and toughness of the cured product.

The present invention contains a cationically polymerizable compound, olefinic rubber particles, a photocationic polymerization initiator, and an alkaline earth metal-based and/or magnesium-based water absorbent filler, wherein the olefinic rubber particles have a core-shell structure. It is an encapsulant for organic electroluminescence display elements.

The present invention is described in detail below.

The present inventor studied various moisture absorbents in order to improve the barrier property (moisture penetration prevention) of the encapsulant for organic EL display elements and found that when an alkaline earth metal such as calcium oxide and/or magnesium based absorbent filler was used, , it was found that particularly excellent barrier properties were exhibited. However, when such an absorbent filler is used, the resulting cured product of the encapsulant for organic EL display elements swells in reliability tests under high temperature, high humidity conditions, etc., and when a roll bonding process is performed or a flexible substrate is used. In some cases, there was a problem of cracks occurring due to bending.

Therefore, as a result of intensive study, the present inventor used a combination of a cationically polymerizable compound and olefin-based rubber particles having a core-shell structure as a resin component, and dispersed the alkaline earth metal-based and/or magnesium-based absorbent filler, It was discovered that an encapsulant for organic EL display elements excellent in both barrier properties and toughness of the cured product could be obtained, and the present invention was completed.

The encapsulant for organic EL display elements of the present invention contains a cationically polymerizable compound. Examples of the cationically polymerizable compound include compounds having an epoxy group, oxetanyl group, vinyl ether group, etc. as a cationically polymerizable group.

As the cationically polymerizable compound, a compound having an epoxy group is preferable. Among them, at least one type of epoxy resin selected from the group consisting of an epoxy resin with a bisphenol skeleton, an epoxy resin with a novolac skeleton, an epoxy resin with a naphthalene skeleton, and an epoxy resin with a dicyclopentadiene skeleton is preferable, An epoxy resin having a bisphenol skeleton is more preferable, and a bisphenol A-type epoxy resin and a bisphenol F-type epoxy resin are further preferable.

Moreover, as the cationically polymerizable compound, you may contain a compound represented by the following formula (1) and/or a compound represented by the following formula (2) from the viewpoint of suppressing the generation of outgas.

[Formula 1]

In formula (1), R ¹ to R ¹⁸ are hydrocarbon groups that may contain a hydrogen atom, a halogen atom, an oxygen atom, or a halogen atom, and may be the same or different. X is a bond, an oxygen atom, an alkylene group having 1 to 5 carbon atoms, an oxycarbonyl group, an alkyleneoxycarbonyl group having 2 to 5 carbon atoms, or a secondary amino group.

[Formula 2]

In formula (2), R ¹⁹ to R ²¹ are linear or branched alkylene groups having 2 to 10 carbon atoms, and may be the same or different. E ¹ to E ³ each independently represent an organic group represented by the following formula (3-1) or the following formula (3-2).

[Formula 3]

In formula (3-1), R ²² is a hydrogen atom or a methyl group.

Examples of the compound represented by the formula (1) and/or the compound represented by the formula (2) include a compound represented by the formula (4-1), a compound represented by the formula (4-2), and a compound represented by the formula (4-3) ), at least one selected from the group consisting of compounds represented by is preferable.

[Formula 4]

Among the above cationically polymerizable compounds, commercially available ones include, for example, EPICLON EXA-830LVP (manufactured by DIC Corporation), jER 4005P (manufactured by Mitsubishi Chemical Corporation), Celoxide 8000, Celoxide 2021P (all manufactured by Daicel Corporation), TEPIC -VL (manufactured by Nissan Chemical Company), etc. can be mentioned.

The encapsulant for organic EL display elements of the present invention contains olefinic rubber particles.

The olefinic rubber particles have a core-shell structure.

By containing olefinic rubber particles having the above core-shell structure, the resulting cured product of the encapsulant for organic EL display elements has excellent toughness. In addition, since olefinic rubber particles have lower decomposability than other rubber particles, they also have the effect of suppressing the generation of outgassing.

From the viewpoint of dispersibility in the cationically polymerizable compound, the olefin-based rubber particles include a core layer made of conjugated diene-based rubber and a shell layer made of a resin having segments derived from a compound having a polymerizable unsaturated double bond. It is desirable to have it.

Examples of the conjugated diene rubber include butadiene rubber, styrene-butadiene rubber, isoprene rubber, and chloroprene rubber. Among them, butadiene rubber is preferable.

Moreover, it is preferable that the said conjugated diene rubber has a glass transition temperature (Tg) of 0 degrees C or less.

Examples of the compound having the polymerizable unsaturated double bond include (meth)acrylic compounds, styrene-based compounds, and acrylonitrile-based compounds. Among them, (meth)acrylic compounds are preferable.

In addition, in this specification, the above “(meth)acryl” means acrylic or methacryl.

Among the above (meth)acrylic compounds, monofunctional ones include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate. ) Acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, bicyclo Pentenyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4- Hydroxybutyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth) Acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth) Acrylate, ethylcarbitol (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H, 1H, 5H-octafluoropentyl (meth)acrylate, imide (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethylsuccinic acid , 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl-2-hydroxypropylphthalate, glycidyl (meth)acrylate, 2-(meth)acryloyl Oxyethyl phosphate, etc. are mentioned.

In addition, in this specification, the “(meth)acrylate” means acrylate or methacrylate, and the “(meth)acryloyl” means acryloyl or methacryloyl.

Among the above (meth)acrylic compounds, bifunctional ones include, for example, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. ) Acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth) Acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate Rate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene oxide added bisphenol A di(meth)acrylate, ethylene oxide added bisphenol A di(meth)acrylate, ethylene oxide added bisphenol F. Di(meth)acrylate, dimethylol dicyclopentadienyl di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide addition isocyanuric acid di(meth)acrylate, 2-hydroxy-3-( Meth)acryloyloxypropyl (meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polycaprolactone diol di(meth)acrylate Acrylate, polybutadienediol di(meth)acrylate, etc. can be mentioned.

Among the above (meth)acrylic compounds, those having three or more functions include, for example, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, propylene oxide addition trimethylolpropane tri(meth)acrylate, Ethylene oxide added trimethylolpropane tri(meth)acrylate, caprolactone modified trimethylolpropane tri(meth)acrylate, ethylene oxide added isocyanuric acid tri(meth)acrylate, glycerin tri(meth)acrylate, propylene oxide. Addition glycerin tri(meth)acrylate, tris(meth)acryloyloxyethyl phosphate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate late, dipentaerythritol hexa(meth)acrylate, etc.

Examples of the styrene-based compound include styrene, α-methylstyrene, and divinylbenzene.

Examples of the acrylonitrile-based compound include acrylonitrile and methacrylonitrile.

As long as the olefinic rubber particle has the core-shell structure, it may be a two-layer structure consisting of the core layer and the shell layer, or may be a multilayer structure of three or more layers further having an intermediate layer between the core layer and the shell layer.

The olefinic rubber particles have a preferable lower limit of average particle diameter of 10 nm and a preferable upper limit of 2000 nm. When the average particle diameter of the olefinic rubber particles is 10 nm or more, the resulting cured product of the encapsulant for organic EL display elements has more excellent toughness. When the average particle diameter of the olefinic rubber particles is 2000 nm or less, the coverage of the shell layer increases and transparency when used as a cotton material becomes more excellent. The more preferable upper limit of the average particle diameter of the olefinic rubber particles is 300 nm, and the more preferable upper limit is 100 nm.

In addition, the average particle diameter of the olefinic rubber particles can be measured using, for example, a laser diffraction type particle size distribution measuring device. As the laser diffraction type particle size distribution measuring device, Mastersizer 2000 (manufactured by Marubansa) or the like can be used.

The content of the olefinic rubber particles has a preferable lower limit of 5.0 parts by weight and a preferable upper limit of 80 parts by weight based on 100 parts by weight of the cationically polymerizable compound. When the content of the olefinic rubber particles is 5.0 parts by weight or more, the resulting cured product of the encapsulant for organic EL display elements has more excellent toughness. When the content of the olefinic rubber particles is 80 parts by weight or less, the resulting cured product of the encapsulant for organic EL display elements has more excellent barrier properties. The more preferable lower limit of the content of the olefinic rubber particles is 10 parts by weight, and the more preferable upper limit is 70 parts by weight.

The encapsulant for organic EL display elements of the present invention contains a photocationic polymerization initiator.

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.

For example, the ionic acid-generating photocationic polymerization initiator has an anionic moiety of BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , or (BX ₄ ) ^- (where X is at least 2 an aromatic sulfonium salt, an aromatic iodonium salt, an aromatic diazonium salt, an aromatic ammonium salt, or (2,4-cyclopentadien-1-yl), which represents a phenyl group substituted with one or more fluorine or trifluoromethyl groups. ((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, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluoro Phosphate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfidebishexafluoroantimonate, bis(4-(di(4-(2-hyde) Roxyethoxy))phenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide tetrakis( Pentafluorophenyl)borate, etc. can be mentioned.

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 photocationic polymerization initiator include nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenol sulfonic acid ester, diazonaphthoquinone, N-hydroxyimide sulfonate, etc. .

Among the photocationic polymerization initiators, commercially available ones include, for example, DTS-200 (manufactured by Midori Chemical Co., Ltd.), UVI6990, UVI6974 (all manufactured by Union Carbide Co., Ltd.), SP-150, and SP-170 (all manufactured by ADEKA Co., Ltd.) , FC-508, FC-512 (all manufactured by 3M), IRGACURE261 (manufactured by BASF), and PI2074 (manufactured by Rhodia).

The content of the photocationic polymerization initiator has a preferable lower limit of 0.1 parts by weight and a preferable upper limit of 10 parts by weight with respect to 100 parts by weight of the cationically polymerizable compound. When the content of the photocationic polymerization initiator is 0.1 part by weight or more, the obtained sealing agent for organic EL display elements has better photocurability. When the content of the photocationic polymerization initiator is 10 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. The more preferable lower limit of the content of the photocationic polymerization initiator 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 contains an alkaline earth metal-based and/or magnesium-based water absorbent filler. By containing the alkaline earth metal-based and/or magnesium-based water absorbent filler, the obtained cured product of the encapsulant for organic EL display elements has excellent barrier properties.

Examples of the alkaline earth metal-based and/or magnesium-based absorbent filler include calcium oxide, magnesium oxide, barium oxide, and strontium oxide. Among them, from the viewpoint of water absorption, it is preferable to contain calcium oxide and/or magnesium oxide, and it is more preferable to contain calcium oxide with a specific surface area of less than 10.0 m2/g as the alkaline earth metal-based absorbent filler.

In addition, when containing a combination of an alkaline earth metal-based absorbent filler and a magnesium-based absorbent filler, it is preferable to contain a combination of calcium oxide and magnesium oxide, and light carbonate (obtained by heating dolomite, which is a double salt of calcium carbonate and magnesium carbonate) It is more preferable to contain dolomite.

The content of the alkaline earth metal-based and/or magnesium-based absorbent filler has a preferable lower limit of 3.0 parts by weight and a preferable upper limit of 100 parts by weight, based on 100 parts by weight of the cationically polymerizable compound. When the content of the alkaline earth metal-based and/or magnesium-based water absorbent filler is 3.0 parts by weight or more, the obtained cured product of the encapsulant for organic EL display elements has better barrier properties. When the content of the alkaline earth metal-based and/or magnesium-based water absorbent filler is 100 parts by weight or less, the toughness of the cured product of the resulting organic EL display element encapsulant is improved, and the effect of suppressing the occurrence of cracks and panel peeling is more effective. It becomes excellent. The more preferable lower limit of the alkaline earth metal and/or magnesium absorbent filler content is 5.0 parts by weight, and the more preferable upper limit is 80 parts by weight.

In addition, the total surface area of the alkaline earth metal-based and/or magnesium-based water absorbent filler has a preferable lower limit of 10 m 2 and a preferable upper limit of 200 m 2 per 100 g of the cationically polymerizable compound. When the total surface area of the alkaline earth metal-based and/or magnesium-based water absorbent filler is 10 m 2 or more, the obtained cured product of the encapsulant for organic EL display elements has more excellent barrier properties. When the total surface area of the alkaline earth metal-based and/or magnesium-based water absorbent filler is 200 m 2 or less, the toughness of the cured product of the resulting organic EL display element encapsulant is improved, and the effect of suppressing the occurrence of cracks and panel peeling is more effective. It becomes excellent. The preferable lower limit of the total surface area of the alkaline earth metal-based and/or magnesium-based absorbent filler is 20 m2, and the preferable upper limit is 150 m2.

Additionally, the total surface area of the alkaline earth metal and/or magnesium-based absorbent filler is calculated from the content of the alkaline earth metal and/or magnesium-based absorbent filler and the BET specific surface area. Specifically, for example, it is calculated from the BET specific surface area measured using nitrogen gas with a specific surface area measuring device (ASAP-2000, manufactured by Shimadzu Corporation).

The encapsulant for organic EL display elements of the present invention is for the purpose of improving adhesion, etc., and is added to the alkaline earth metal-based and/or magnesium-based absorbent filler within a range that does not impair the purpose of the present invention. Therefore, other fillers may be contained.

Examples of the other fillers include inorganic fillers such as silica, talc, and alumina, and organic fillers such as polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and acrylic polymer fine particles. Among them, talc is preferable because it is excellent in the effect of improving moisture resistance.

The content of the other fillers has a preferable lower limit of 5 parts by weight and a preferable upper limit of 100 parts by weight based on 100 parts by weight of the cationically polymerizable compound. When the content of the other fillers is within this range, the effect of improving adhesion can be sufficiently achieved without deteriorating the applicability of the resulting sealant for organic EL display elements. The more preferable lower limit of the content of the other fillers is 10 parts by weight, and the more preferable upper limit is 80 parts by weight.

The encapsulant for organic EL display elements of the present invention may contain a thermosetting agent. Examples of thermal curing agents include hydrazide compounds, imidazole derivatives, acid anhydrides, dicyandiamide, guanidine derivatives, modified aliphatic polyamines, and addition products of various amines and epoxy resins.

Examples of the hydrazide compounds include 1,3-bis(hydrazinocarbonoethyl-5-isopropylhydantoin), sebacic acid dihydrazide, isophthalic acid dihydrazide, and adipic acid dihydrazide. Drazide, malonic acid dihydrazide, etc. can be mentioned.

Examples of the imidazole derivative include 1-cyanoethyl-2-phenylimidazole, N-(2-(2-methyl-1-imidazolyl)ethyl)urea, and 2,4-diamino. -6-(2'-Methylimidazolyl-(1'))-ethyl-s-triazine, N,N'-bis(2-methyl-1-imidazolylethyl)urea, N,N'- (2-methyl-1-imidazolylethyl)-adipoamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4, 5-dihydroxymethylimidazole, etc. can be mentioned.

Examples of the acid anhydride include tetrahydrophthalic anhydride, ethylene glycol bis(anhydrotrimellitate), and the like.

These thermosetting agents may be used individually, or two or more types may be used together.

Among the above-mentioned heat curing agents, commercially available ones include, for example, SDH (manufactured by Nippon Fine-Chem), ADH (manufactured by Otsuka Chemical Company), Amicure VDH, Amicure VDH-J, and Amicure UDH (all manufactured by Ajinomoto Fine Techno). etc. can be mentioned.

The content of the thermosetting agent has a preferable lower limit of 0.5 parts by weight and a preferable upper limit of 30 parts by weight based on 100 parts by weight of the cationically polymerizable compound. When the content of the heat curing agent is 0.5 parts by weight or more, the obtained sealing agent for organic EL display elements has better heat curing properties. When the content of the thermosetting agent is 30 parts by weight or less, the obtained sealing agent for organic EL display elements has better storage stability, and the cured product has more excellent moisture resistance. The more preferable lower limit of the content of the heat curing agent is 1 part by weight, and the more preferable upper limit is 15 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 photocationic 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 anthracene-based compounds such as 9,10-dibutoxyanthracene, thioxanthone-based compounds such as 2,4-diethylthioxanthone, 2,2-dimethoxy-1, 2-diphenylethan-1-one, benzophenone, 2,4-dichlorobenzophenone, o-benzoylmethyl benzoate, 4,4'-bis(dimethylamino)benzophenone, 4-benzoyl-4'-methyldiphenyl Sulfide, etc. can be mentioned.

The content of the sensitizer has a preferable lower limit of 0.05 parts by weight and a preferable upper limit of 3 parts by weight based on 100 parts by weight of the cationically polymerizable compound. When the content of the sensitizer is 0.05 parts by weight or more, the sensitizing effect is more exhibited. When the content of the sensitizer is 3 parts by weight or less, light can be transmitted to the deep part without 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.

The encapsulant for organic EL display elements of the present invention preferably contains a stabilizer for the purpose of improving storage stability.

Examples of the stabilizer include amine-based compounds and aminophenol-type epoxy resins.

The content of the stabilizer has a preferable lower limit of 0.001 parts by weight and a preferable upper limit of 2 parts by weight based on 100 parts by weight of the cationically polymerizable compound. When the content of the stabilizer is within this range, the effect of suppressing curing inhibition and improving the storage stability of the resulting encapsulant for organic EL display elements becomes more excellent. A more preferable lower limit of the content of the stabilizer is 0.05 parts by weight, and a more preferable upper limit is 1 part 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 cationically polymerizable compound. When the content of the silane coupling agent is within this range, the effect of improving the adhesiveness of the resulting encapsulant for organic EL display elements becomes more excellent while suppressing bleed-out due to 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 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 surfactant and the leveling agent include silicone-based, acrylic-based, and fluorine-based agents.

Among the surfactants and leveling agents that are commercially available, for example, BYK-345, BYK-340 (all manufactured by Big Chemie Japan), Surfron S-611 (manufactured by AGC Semichemical Company), etc. I can hear it.

The encapsulant for organic EL display elements of the present invention may contain an ion exchange resin in order to improve the durability of the element electrode within a range that does not impair the purpose of the present invention.

As the ion exchange resin, cation exchange type, anion exchange type, and both ion exchange type can be used, but cation exchange type or both ion exchange type that can adsorb chloride ions are particularly preferred.

In addition, the encapsulant for organic EL display elements of the present invention may include known curing retarders, reinforcing agents, softeners, plasticizers, viscosity modifiers, ultraviolet absorbers, antioxidants, etc., as necessary, within the range that does not impair the purpose of the present invention. It may contain various additives.

As a method for producing the encapsulant for organic EL display elements of the present invention, for example, using a mixer such as a homodisper, homomixer, universal mixer, planetary mixer, kneader, or three roll, cation Examples include a method of mixing a polymerizable compound, olefinic rubber particles, a photocationic polymerization initiator, an alkaline earth metal-based and/or magnesium-based water absorbent filler, and additives added as needed. The olefinic rubber particles may be dispersed in advance in the cationically polymerizable compound and then mixed with other components.

When the sealing agent for organic EL display elements of the present invention is intended for in-plane sealing, the lower limit of the viscosity measured using an E-type viscometer at 25°C is 50 mPa·s, and the upper limit is 8000 mPa·s. am. When the viscosity is within this range, the obtained sealing agent for organic EL display elements of the present invention has superior applicability and transparency of the cured product. The more preferable lower limit of the viscosity is 60 mPa·s, the more preferable upper limit is 3000 mPa·s, the more preferable lower limit is 70 mPa·s, and the more preferable upper limit is 1000 mPa·s.

In addition, the above viscosity can be measured, for example, by using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer, and using a cone plate of CP1, from the optimal torque number in each viscosity range, as appropriate, from 1 to 100 rpm. It can be measured by selecting the number of rotations.

When the encapsulant for organic EL display elements of the present invention is intended for encapsulation of peripheral surfaces, the lower limit of viscosity at 25°C, as measured using an E-type viscometer, is preferably 100 Pa·s, and the upper limit is preferably 500 Pa·s. am. When the viscosity is within this range, a decrease in the contact area due to insertion due to a pressure difference during vacuum bonding is prevented, and the applicability and shape stability after application are improved. The more preferable lower limit of the viscosity is 200 Pa·s, the more preferable upper limit is 400 Pa·s, the more preferable lower limit is 250 Pa·s, and the more preferable upper limit is 350 Pa·s.

In addition, the above viscosity can be measured, for example, by using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer, and using a CP7 cone plate, from the optimal torque number in each viscosity range, as appropriate, from 1 to 100 rpm. It can be measured by selecting the number of rotations.

The shape of the sealing portion formed in the encapsulant for organic EL display elements of the present invention 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 can be completely sealed. It may be in a covering shape, a closed pattern may be formed on the periphery of the laminate, or a pattern with some openings may be formed on the periphery of the laminate. It can be preferably used for encapsulation of the periphery of the laminate. there is.

According to the present invention, it is possible to provide an encapsulant for an organic electroluminescent display device having excellent barrier properties and toughness of the cured product.

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

(Production of olefinic rubber particles A with core-shell structure)

In a reaction vessel in which oxygen was sufficiently removed and nitrogen substitution was performed, 100 parts by weight of butadiene, 200 parts by weight of deionized water, 0.05 parts by weight of tripotassium phosphate, 0.04 parts by weight of potassium dihydrogen phosphate, 0.002 parts by weight of disodium ethylenediaminetetraacetate, and sulfuric acid were added. 0.001 parts by weight of ferrous heptahydrate and 1.5 parts by weight of sodium dodecylbenzenesulfonate were added, and stirred and mixed at 45°C. Next, 0.015 parts by weight of paramenthan hydroperoxide and 0.04 parts by weight of sodium formaldehyde sulfoxylate were added to initiate the polymerization reaction. Five hours after the start of the polymerization reaction, an additional 0.01 part by weight of paramenthan hydroperoxide, 0.002 part by weight of disodium ethylenediaminetetraacetate, and 0.001 part by weight of iron were added. 10 hours after the start of the polymerization reaction, the remaining monomer was removed to complete the polymerization, and latex (X-1) containing polybutadiene rubber particles was obtained.

300 parts by weight of deionized water was added to a reaction vessel containing 1500 parts by weight of latex (X-1) containing the obtained polybutadiene rubber particles, and stirred at 50° C. under a nitrogen atmosphere. Additionally, after adding 0.01 parts by weight of disodium ethylenediaminetetraacetate, 0.005 parts by weight of iron, and 0.24 parts by weight of sodium formaldehyde sulfoxylate, 90 parts by weight of methyl methacrylate and t-butyl hydroperoxide were added as graft monomers. 0.08 parts by weight was added over 2 hours to proceed with graft polymerization. The polymerization was terminated 2 hours after the start of the polymerization reaction, and latex containing olefinic rubber particles A with a core-shell structure was obtained.

The average particle diameter of the obtained olefinic rubber particles A having a core-shell structure was 100 nm.

(Production of olefinic rubber particles B with core-shell structure)

Except that instead of 100 parts by weight of butadiene, 75 parts by weight of butadiene and 25 parts by weight of styrene were added to the reaction vessel, in the same manner as in “(Production of olefinic rubber particles A with core-shell structure)”, the core layer was made of butadiene. -Olefin-based rubber particles B (average particle diameter 100 nm) having a core-shell structure made of styrene rubber were produced.

(Production of olefinic rubber particles C with core-shell structure)

As the graft monomer, instead of 90 parts by weight of methyl methacrylate, a mixture of 80 parts by weight of methyl methacrylate and 10 parts by weight of triallyl isocyanurate was used. In the same manner as in “Manufacture),” olefinic rubber particles C (average particle diameter: 100 nm) having a core-shell structure in which the core layer is made of butadiene-styrene rubber were produced.

(Example 1)

As a cationically polymerizable compound, 80 parts by weight of bisphenol F-type epoxy resin (“EPICLON EXA-830LVP”, manufactured by DIC) and 20 parts by weight of solid bisphenol F-type epoxy resin (“jER 4005P”, manufactured by Mitsubishi Chemical Corporation), 50 parts by weight of the prepared olefinic rubber particles A having a core-shell structure were added and stirred and mixed uniformly. Next, 1.0 parts by weight of an aromatic iodonium salt (“PI2074” manufactured by Rhodia) was added as a photocationic polymerization initiator, and dissolved by heating at 60°C for 1 hour, followed by adding 0.2 parts by weight of 9,10-dibutoxyanthracene and silane as sensitizers. 3.0 parts by weight of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., “KBM-403”) as a coupling agent, calcium oxide (manufactured by Yoshizawa Lime Industry Co., Ltd., “Quick Lime J1P”) as an absorbent filler, specific surface area 2.5 m2/ g) Add 40 parts by weight and 50 parts by weight of talc (“MICRO ACE FG-15” manufactured by Nippon Talc Co., Ltd.) as other fillers, and using a stirring mixer (“AR-250” manufactured by Shinki Co., Ltd.), stir at a stirring speed of By uniformly stirring and mixing at 3000 rpm, an encapsulant for organic EL display elements was produced.

(Examples 2 to 12, Comparative Examples 1 to 5)

Each material in the mixing ratio shown in Table 1 and Table 2 was stirred and mixed in the same manner as in Example 1 to produce a sealant for organic EL display elements.

＜Evaluation＞

The following evaluation was performed on each of the encapsulants for organic EL display elements obtained in the examples and comparative examples. The results are shown in Table 1 and Table 2.

(1) Viscosity

For each of the encapsulants for organic EL display elements obtained in the examples and comparative examples, the viscosity (initial viscosity) at 25°C was measured using an E-type viscometer (“VISCOMETER TV-22”, manufactured by Toki Sangyo Co., Ltd.). .

(2) Barrier properties of cured product

The following Ca-TEST was performed on each of the sealing agents for organic EL display elements obtained in the examples and comparative examples.

First, a 30 mm x 30 mm glass substrate was covered with a mask having a plurality of 2 mm x 2 mm openings, and Ca was deposited using a vacuum evaporator. The conditions for deposition were to reduce the pressure inside the evaporator of the vacuum evaporation device to 2 × 10 ^-3 Pa and to form a 2000 Å film of Ca at a deposition rate of 5.0 Å/s. The glass substrate on which Ca was deposited was moved into a glow box controlled at a dew point (-60°C or higher), and the glass substrates to which each organic EL display device sealant obtained in the examples and comparative examples were applied were bonded to the surface. At this time, the bonding was performed so that the Ca deposited at positions of 2 mm, 4 mm, and 6 mm from the end surface of the glass substrate was present. Next, 3000 mJ/cm 2 of ultraviolet rays of 365 nm were irradiated and the encapsulant was cured by further heating at 80°C for 30 minutes to produce a Ca-TEST substrate. The obtained Ca-TEST substrate was exposed to high temperature and high humidity conditions of 85°C and 85%RH, and the penetration distance of moisture over time was observed based on the disappearance of CA.

As a result of Ca-TEST, the time until the moisture intrusion distance reaches 6 mm is marked as “◎” if it is 1000 hours or more, “○” if it is 500 hours or more but less than 1000 hours, and “○” if it is 100 hours or more but less than 500 hours. The barrier properties of the cured product were evaluated by setting △” for less than 100 hours as “×”.

(3) Toughness of hardened product

Each of the encapsulants for organic EL display elements obtained in the examples and comparative examples was irradiated with 3000 mJ/cm 2 of ultraviolet rays at 365 nm, and further heated at 80°C for 30 minutes to obtain a cured product. For the obtained hardened product, the fracture toughness value K _IC was determined according to JIS R1607 (IF method). As a result, the toughness of the cured product was evaluated by setting the fracture toughness value K _IC of 1.0 or more as “○”, the case of 0.8 or more but less than 1.0 as “△”, and the case of less than 0.8 as “×”.

(4) Adhesion status of panels

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

An ITO electrode was formed to a thickness of 1000 Å on a glass substrate (length 25 mm, width 25 mm, thickness 0.7 mm), which was used as a substrate. 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 (manufactured by Nippon Laser Electronics). The previous treatment was performed with “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 different 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, and an organic light-emitting material layer with a film thickness of 600 Å was formed 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 apparatus, and 200 mg of lithium fluoride was placed in a tungsten resistance heating boat in this vacuum evaporation apparatus, and 1.0 g of aluminum wire was placed in another tungsten boat. ^Afterwards , the pressure inside the evaporator of the vacuum evaporation device was reduced to 2 . 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.

(Covering with inorganic material film A)

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

The plasma CVD method uses SiH ₄ gas and nitrogen gas as raw material gases, each flow rate is 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. It was carried out at 100°C and the pressure in the chamber was 0.9 Torr.

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

(Formation of resin protective film)

A substrate on which a laminate covered with an inorganic material film A was disposed was placed in a vacuum apparatus, and 0.5 g of each organic EL display element encapsulant obtained in the examples and comparative examples was placed in a heating boat installed in the vacuum apparatus, and the pressure was reduced to 10 Pa. Then, the encapsulant for organic EL display elements was heated at 200°C on a 11 mm × 11 mm square portion containing the laminated body, and vacuum deposition was performed so that the thickness was 0.5 μm. After that, ultraviolet rays with a wavelength of 365 nm were irradiated at an irradiation amount of 3000 mJ/cm2 using a high-pressure mercury lamp in a vacuum environment, and the encapsulant for organic EL display elements was cured to form a resin protective film.

(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 uses SiH ₄ gas and nitrogen gas as raw material gases, each flow rate is 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. It was carried out at 100°C and the pressure in the chamber was 0.9 Torr.

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

(Observation of panel adhesion condition)

The obtained organic EL display element was exposed to an environment of 85°C and 85%RH for 500 hours, and then the adhesion state of the panel was observed with the naked eye. The adhesion state of the panels was evaluated by assigning “○” to cases where there was no panel peeling, “△” to cases where some panel peeling was confirmed, and “×” to cases where panel peeling was confirmed to be the majority.

(5) Reliability of organic EL display elements

The organic EL display element obtained in the same manner as in "(4) Panel adhesion condition" above was exposed to an environment of 85°C and 85%RH for 500 hours, and then a voltage of 3 V was applied to cause light emission of the organic EL display element. The condition (presence or absence of dark spots and extinction around the pixel) was observed with the naked eye. The reliability of the organic EL display element was evaluated by setting the case where there was no dark spot or ambient light and emitting light uniformly as “○”, and the case where even a slight dark spot or ambient light was confirmed as “×”.

According to the present invention, it is possible to provide an encapsulant for an organic electroluminescent display device having excellent barrier properties and toughness of the cured product.

Claims (5)

Contains a cationically polymerizable compound, olefinic rubber particles, a photocationic polymerization initiator, and an alkaline earth metal absorbent filler,
The olefin-based rubber particles have a core layer made of conjugated diene-based rubber and a shell layer made of a resin having segments derived from a compound having a polymerizable unsaturated double bond. A bag for an organic electroluminescence display device, characterized in that my. delete According to claim 1,
An encapsulant for an organic electroluminescent display element, characterized in that the content of olefinic rubber particles is 5.0 to 80 parts by weight based on 100 parts by weight of the cationically polymerizable compound. According to claim 1,
An encapsulant for an organic electroluminescence display device, which is an alkaline earth metal-based absorbent filler and contains calcium oxide and/or magnesium oxide. According to claim 4,
An encapsulant for an organic electroluminescence display device, which is an alkaline earth metal-based water absorbent filler and contains calcium oxide with a specific surface area of less than 10.0 m2/g.