JP6933580B2 - Encapsulant for organic electroluminescence display elements - Google Patents

Description

The present invention relates to a sealing agent for an organic electroluminescent display element, which has excellent barrier properties and can suppress panel peeling.

The organic electroluminescence (hereinafter, also referred to as “organic EL”) display element has a laminated structure in which an organic light emitting material layer is sandwiched between a pair of electrodes facing each other, and the organic light emitting material layer is connected to the organic light emitting material layer from one electrode. When the electrons are injected and the holes are injected from the other electrode, the electrons and holes are combined and emit light in the organic light emitting material layer. Since the organic EL display element emits light by itself in this way, it has better visibility than a liquid crystal display element or the like that requires a backlight, can be made thinner, and can be driven by a low DC voltage. It has the advantage of.

The organic light emitting material layer and electrodes constituting the organic EL display element have a problem that their characteristics are easily deteriorated by moisture, oxygen, and the like. Therefore, in order to obtain a practical organic EL display element, it is necessary to shield the organic light emitting material layer and the electrode from the atmosphere to extend the life. As a method of blocking the organic light emitting material layer and the electrode from the atmosphere, an organic EL display element is sealed with a sealing agent (for example, Patent Document 1). When the organic EL display element is sealed with a sealing agent, an inorganic film called a passivation film is usually provided on a laminate having an organic light emitting material layer in order to sufficiently suppress the permeation of moisture, oxygen, etc., and the inorganic film is provided. A method of sealing the top with a sealant is used.

In recent years, instead of the bottom emission type organic EL display element that extracts the light emitted from the organic light emitting material layer from the substrate surface side on which the light emitting element is formed, the top emission type organic that extracts the light from the upper surface side of the organic light emitting layer. EL display elements are attracting attention. This method has an advantage of extending the life because it has a high aperture ratio and is driven by 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, a transparent moisture-proof group such as glass is interposed on the upper surface side of the light emitting element via a transparent sealing resin. It is sealed by laminating the materials (see, for example, Patent Document 2).
However, in such a top emission type organic EL display element, there is no space for arranging a desiccant so as not to block the light extraction direction, and it is difficult to obtain a sufficient moisture-proof effect and the life is short. There was a problem of becoming.

JP-A-2007-115692 Japanese Unexamined Patent Publication No. 2009-051980

An object of the present invention is to provide a sealing agent for an organic electroluminescent display element, which has excellent barrier properties and can suppress panel peeling.

The present invention contains a curable resin, a polymerization initiator, and a water-absorbent filler, and the water-absorbent filler has an average primary particle size of 5 μm or less and a specific gravity of 3.3 g / cm ³ or less. A sealant for display elements.
The present invention will be described in detail below.

The present inventor has attempted to add a water-absorbing filler such as calcium oxide in order to improve the barrier property (moisture permeation prevention property) of the sealing agent for an organic EL display element. However, when a large amount of a commercially available water-absorbent filler is added to the sealing agent for an organic EL display element, although the barrier property can be improved, the expansion rate is high, so that it absorbs water and causes defects such as panel peeling. There was a problem.
Therefore, as a result of further diligent studies, the present inventor has excellent barrier properties and can suppress panel peeling by using a water-absorbent filler in which the average primary particle size and the specific gravity are in specific ranges, respectively, for an organic EL display element. They have found that a sealing agent can be obtained, and have completed the present invention.

The sealant for an organic EL display element of the present invention has an average primary particle size of 5 μm or less and a specific gravity of 3.3 g / cm ³ or less (hereinafter, also referred to as “water-absorbent filler according to the present invention”). ). By containing the water-absorbent filler according to the present invention, the sealing agent for an organic EL display element of the present invention has excellent barrier properties and can suppress panel peeling.

The following can be considered as the reason why the panel peeling can be suppressed by containing the water-absorbent filler according to the present invention.
That is, the water-absorbent filler according to the present invention has the above-mentioned average primary particle size and specific gravity, and has a smaller specific gravity and a higher porosity than a general water-absorbent filler having the same average primary particle size. It is considered to have. Therefore, when water is absorbed, it is considered that the expansion to the outside is suppressed by filling the internal voids, and as a result, the panel peeling can be suppressed while exhibiting the excellent barrier property due to the high water absorption performance.

The upper limit of the average primary particle size of the water-absorbent filler according to the present invention is 5 μm. When the average primary particle size of the water-absorbent filler according to the present invention is 5 μm or less, the obtained sealing agent for an organic EL display element has an excellent effect of achieving both excellent barrier properties and suppression of panel peeling. .. The preferable upper limit of the average primary particle size of the water-absorbent filler according to the present invention is 3.5 μm, and the more preferable upper limit is 3 μm.
Further, the lower limit of the average primary particle size of the water-absorbent filler according to the present invention is not particularly limited, but the practical lower limit is 0.05 μm, and those having a size of 0.5 μm or more are more easily available.
The "average primary particle size" can be measured by a dynamic light scattering type particle size measuring device ("ELSZ-1000S" manufactured by Otsuka Electronics Co., Ltd.) or the like.

The upper limit of the specific gravity of the water-absorbent filler according to the present invention is 3.3 g / cm ³ . When the specific gravity of the water-absorbent filler according to the present invention is 3.3 g / cm ³ or less, the obtained sealing agent for an organic EL display element is excellent in both excellent barrier properties and suppression of panel peeling. It becomes. The preferable upper limit of the specific gravity of the water-absorbent filler according to the present invention is 3.0 g / cm ³ .
Further, the lower limit of the specific gravity of the water-absorbent filler according to the present invention is not particularly limited, but the practical lower limit is 1.5 g / cm ³ .
The above "specific gravity" means a value measured by a method according to JIS Z8807.

The preferable lower limit of the average specific surface area of the water-absorbent filler according to the present invention is 5 m ² / g, and the preferable upper limit is 20 m ² / g. When the average specific surface area of the water-absorbent filler according to the present invention is within this range, the obtained sealing agent for an organic EL display element is excellent in the effect of achieving both excellent barrier properties and suppression of panel peeling. The more preferable lower limit of the average specific surface area of the total surface area of the water-absorbent filler according to the present invention is 10 m ² / g, and the more preferable upper limit is 18 m ² / g.
The "average specific surface area" can be measured by a BET method using nitrogen gas with a specific surface area measuring device (for example, "ASAP-2000" manufactured by Shimadzu Corporation).

The preferable lower limit of the water absorption rate of the water-absorbent filler according to the present invention is 10% by weight. When the water absorption rate of the water-absorbent filler according to the present invention is 10% by weight or more, the obtained sealing agent for an organic EL display element has a better barrier property. A more preferable lower limit of the water absorption rate of the water-absorbent filler according to the present invention is 20% by weight.
Further, although there is no particular preferable upper limit of the water absorption rate of the water-absorbent filler according to the present invention, the practical upper limit is 50% by weight.
The "water absorption rate" means the rate of change in weight when a high-temperature and high-humidity test is performed in which the mixture is left in an atmosphere of a temperature of 85 ° C. and a humidity of 85% for 24 hours. Specifically, assuming that the weight before the high temperature and high humidity test (85 ° C.-85%, 24 hours) is W ₁ and the weight after the high temperature and high humidity test is W ₂ , it is calculated by the following formula (I).
Water absorption rate (% by weight) = ((W _2- W ₁ ) / W ₁ ) x 100 (I)

Examples of the material constituting the water-absorbent filler according to the present invention include oxides of alkaline earth metals such as calcium oxide, strontium oxide and barium oxide, magnesium oxide and molecular sieves. Of these, oxides of alkaline earth metals are preferable, and calcium oxide is more preferable, from the viewpoint of water absorption.

Regarding the content of the water-absorbent filler according to the present invention, the preferable lower limit is 5 parts by weight and the preferable upper limit is 60 parts by weight with respect to 100 parts by weight of the curable resin. When the content of the water-absorbent filler according to the present invention is within this range, the obtained sealing agent for an organic EL display element is excellent in the effect of both improving the barrier property and suppressing panel peeling. The more preferable lower limit of the content of the water-absorbent filler according to the present invention is 10 parts by weight, and the more preferable upper limit is 40 parts by weight.

The encapsulant for an organic EL display element of the present invention contains other fillers in addition to the water-absorbent filler according to the present invention, for the purpose of improving adhesiveness and the like, as long as the object of the present invention is not impaired. You may.
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. Of these, talc is preferable.

The sealing agent for an organic EL display element of the present invention contains a curable resin.
Examples of the curable resin include a cationically polymerizable compound having a cationically polymerizable group such as an epoxy group, an oxetanyl group and a vinyl ether group, and a radically polymerizable compound having a radically polymerizable group such as a (meth) acryloyl group. Of these, a cationically polymerizable compound is preferable, and a cationically polymerizable compound having an epoxy group is more preferable.

Examples of the cationically polymerizable compound include an epoxy resin having a bisphenol skeleton, an epoxy resin having a novolak skeleton, an epoxy resin having a naphthalene skeleton, and an epoxy resin having a dicyclopentadiene skeleton from the viewpoint of easy viscosity adjustment. At least one epoxy resin selected from the group consisting of is preferable, an epoxy resin having a bisphenol skeleton is more preferable, and a bisphenol F type epoxy resin is further preferable.

Further, the encapsulant for an organic EL display element of the present invention has a compound represented by the following formula (1) and / or a following formula (2) as the above cationically polymerizable compound from the viewpoint of suppressing the generation of outgas. It preferably contains the compound represented.

In the formula (1), R ^{1 to} R ¹⁸ are hydrocarbon groups which may contain a hydrogen atom, a halogen atom, or an oxygen atom or a halogen atom, and may be the same or different from each other. May be good. 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.

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

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

Among them, as the above-mentioned cationically polymerizable compound, a compound represented by the following formula (4-1), a compound represented by the following formula (4-2), and a compound represented by the following formula (4-3). It is preferable to contain at least one selected from the group consisting of.

Examples of commercially available compounds represented by the above formula (1) include celoxide 8000 and celoxide 2021P (both manufactured by Daicel), and the compounds represented by the above formula (2). Examples of commercially available products include TEPIC-VL (manufactured by Nissan Chemical Industries, Ltd.) and the like.

As the radically polymerizable compound, a (meth) acrylic compound is preferably used.
The (meth) acrylic compound is, for example, an epoxy (meth) acrylate obtained by reacting (meth) acrylic acid with an epoxy compound, or obtained by reacting (meth) acrylic acid with a compound having a hydroxyl group. Examples thereof include a (meth) acrylic acid ester compound and a urethane (meth) acrylate obtained by reacting an isocyanate compound with a (meth) acrylic acid derivative having a hydroxyl group. Of these, epoxy (meth) acrylate is preferable.
In the present specification, the above-mentioned "(meth) acrylic" means acrylic or methacryl, the above-mentioned "(meth) acrylate" means acrylate or methacrylate, and the above-mentioned "epoxy (meth) acrylate" means. It represents a compound in which all epoxy groups in an epoxy resin are reacted with (meth) acrylic acid.

Among the above epoxy (meth) acrylates, commercially available ones include, for example, EBECRYL860, EBECRYL3200, EBECRYL3201, EBECRYL3412, EBECRYL3600, EBECRYL3700, EBECRYL3701, EBECRYL3702, EBECRYL3702, EBECRYL3702, EBECRYL370 , EA-1010, EA-1020, EA-5323, EA-5520, EA-CHD, EMA-1020 (all manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), Epoxy Ester M-600A, Epoxy Ester 40EM, Epoxy Ester 70PA, Epoxy Ester 200PA, Epoxy Ester 80MFA, Ester Ester 3002M, Epoxy Ester 3002A, Ester Ester 1600A, Ester Ester 3000M, Ester Ester 3000A, Epoxy Ester 200EA, Ester Ester 400EA (all manufactured by Kyoeisha Chemical Co., Ltd.), Denacol Acrylate DA-141, Examples thereof include Denacol Acrylate DA-314 and Denacol Acrylate DA-911 (both manufactured by Nagase ChemteX Corporation).

The sealing agent for an organic EL display element of the present invention contains a polymerization initiator.
Examples of the polymerization initiator include a photopolymerization initiator and a thermal polymerization initiator. Of these, a photopolymerization initiator is preferable.

Examples of the photopolymerization initiator include a photocationic polymerization initiator that generates protonic acid or Lewis acid by light irradiation, a photoradical polymerization initiator that generates radicals by light irradiation, and the like. Of these, a photocationic polymerization initiator is preferable.

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

As the ionic photoacid generator type of the cationic photopolymerization initiator, for example, the anionic portion is _{^{BF 4 -, PF 6 -,}} SbF 6 -, or, _(BX 4) ^- (where, X is at least Aromatic sulfonium salt, aromatic iodonium salt, aromatic diazonium salt, aromatic ammonium salt, or (2,4) composed of (representing a phenyl group substituted with two or more fluorine or trifluoromethyl groups). -Cyclopentadiene-1-yl) ((1-methylethyl) benzene) -Fe salt and the like can be mentioned.

Examples of the aromatic sulfonium salt include bis (4- (diphenylsulfonio) phenyl) sulfide bishexafluorophosphate, bis (4- (diphenylsulfonio) phenyl) sulfide bishexafluoroantimonate, and bis (4-( Diphenylsulfonio) phenyl) sulfide bistetrafluoroborate, bis (4- (diphenylsulfonio) phenyl) sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate, diphenyl-4- ( Phenylthio) phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) phenylsulfonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexa Fluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis (4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl) sulfide bishexafluorophosphate, Bis (4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl) sulfide bishexafluoroantimonate, bis (4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl ) Sulfide bistetrafluoroborate, bis (4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl) sulfide tetrakis (pentafluorophenyl) borate and the like can be mentioned.

Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodonium hexafluorophosphate, and bis. (Dodecylphenyl) Iodineium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexa Fluorophosphate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluoroantimonate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrafluoroborate, 4-methylphenyl-4-( 1-Methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate and the like can be mentioned.

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

Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, and 1-benzyl. -2-Cyanopyridinium tetrakis (pentafluorophenyl) boronate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoroantimonate, 1- (naphthylmethyl) Examples thereof include -2-cyanopyridinium tetrafluoroborate and 1- (naphthylmethyl) -2-cyanopyridinium tetrakis (pentafluorophenyl) boronate.

Examples of the (2,4-cyclopentadiene-1-yl) ((1-methylethyl) benzene) -Fe salt include (2,4-cyclopentadiene-1-yl) ((1-methylethyl) benzene). ) -Fe (II) hexafluorophosphate, (2,4-cyclopentadiene-1-yl) ((1-methylethyl) benzene) -Fe (II) hexafluoroantimonate, (2,4-cyclopentadiene-1) -Il) ((1-methylethyl) benzene) -Fe (II) tetrafluoroborate, (2,4-cyclopentadiene-1-yl) ((1-methylethyl) benzene) -Fe (II) tetrakis (penta) Fluorophene) Borate and the like can be mentioned.

Among the above photocationic polymerization initiators, examples of the nonionic photoacid-generating type include nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenol sulfonic acid ester, diazonaphthoquinone, N-hydroxyimide sulfonate and the like. Can be mentioned.

Commercially available photocationic polymerization initiators include, for example, DTS-200 (manufactured by Midori Chemical Co., Ltd.), UVI6990, UVI6974 (all manufactured by Union Carbide), SP-150, and SP-170 (all manufactured by Union Carbide). Examples thereof include ADEKA), FC-508, FC-512 (all manufactured by 3M), IRGACURE290 (BASF), PI2074 (Rodia) and the like.

Examples of the photoradical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanosen compounds, oxime ester compounds, benzoin ether compounds, benzyls, thioxanthones and the like.

Commercially available photoradical polymerization initiators include, for example, IRGACURE184, IRGACURE369, IRGACURE379, IRGACURE651, IRGACURE819, IRGACURE907, IRGACURE2959, IRGACURE OXE01, Lucillin TPO (all manufactured by BASF), benzo. Examples thereof include ethyl ether and benzoin isopropyl ether (both manufactured by Tokyo Chemical Industry Co., Ltd.).

Examples of the thermal polymerization initiator include a thermal cationic polymerization initiator that generates protonic acid or Lewis acid by heating, a thermal radical polymerization initiator that generates radicals by heating, and the like.

As the thermal cationic polymerization _{^{initiator, BF 4 -, PF 6 -}} , SbF 6 -, or, _(BX 4) ^- (where the phenyl X is substituted with at least two or more fluorine or trifluoromethyl group A sulfonium salt, a phosphonium salt, a quaternary ammonium salt, a diazonium salt, or an iodonium salt having (representing a group) as a counter anion is preferable, and a sulfonium salt is more preferable.

Examples of the sulfonium salt include triphenylsulfonium boron trifluoride, triphenylsulfonium hexafluoride antimony, triphenylsulfonium arsenic pentafluoride, tri (4-methoxyphenyl) sulfonium arsenic pentafluoride, and diphenyl (4-phenylthiophenyl). ) Sulfonium arsenic pentafluoride and the like.
Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoride antimony and tetrabutylphosphonium hexafluoride antimony.
Examples of the quaternary ammonium salt include dimethylphenyl (4-methoxybenzyl) ammonium hexafluorophosphate, dimethylphenyl (4-methoxybenzyl) ammonium hexafluoroantimonate, and dimethylphenyl (4-methoxybenzyl) ammonium tetrakis (penta). Fluorophenyl) borate, dimethylphenyl (4-methylbenzyl) ammonium hexafluorophosphate, dimethylphenyl (4-methylbenzyl) ammonium hexafluoroantimonate, dimethylphenyl (4-methylbenzyl) ammonium hexafluorotetrakis (pentafluorophenyl) borate , Methylphenyldibenzylammonium, methylphenyldibenzylammonate hexafluoroantimonate hexafluorophosphate, methylphenyldibenzylammonium tetrakis (pentafluorophenyl) borate, phenyltribenzylammonium tetrakis (pentafluorophenyl) borate, dimethylphenyl (3, 4-Dimethylbenzyl) ammonium tetrakis (pentafluorophenyl) borate, N, N-dimethyl-N-benzylanilinium hexafluoride antimony, N, N-diethyl-N-benzylanilinium tetrafluoride, N, N- Examples thereof include dimethyl-N-benzylpyridinium hexafluoride antimony, N, N-diethyl-N-benzylpyridinium trifluoromethanesulfonic acid and the like.

Commercially available thermal cationic polymerization initiators include, for example, Sun Aid SI-60, Sun Aid SI-80, Sun Aid SI-B3, Sun Aid SI-B3A, and Sun Aid SI-B4 (all of which are Sanshin Chemical Industry Co., Ltd.). CXC-1612, CXC-1738, CXC-1821 (all manufactured by King Industries) and the like.

Examples of the thermal radical polymerization initiator include peroxides and azo compounds, and commercially available products include, for example, perbutyl O, perhexyl O, perbutyl PV (all manufactured by Nichiyu Co., Ltd.), V-30, and the like. Examples thereof include V-65, V-501, V-601, and VPE-0201 (all manufactured by Wako Pure Chemical Industries, Ltd.).

Regarding the content of the polymerization initiator, the preferable lower limit is 0.1 parts by weight and the preferable upper limit is 10 parts by weight with respect to 100 parts by weight of the curable resin. When the content of the polymerization initiator is in this range, the obtained sealing agent for an organic EL display element is excellent in curability, storage stability, and barrier property. The more preferable lower limit of the content of the polymerization initiator is 0.5 parts by weight, and the more preferable upper limit is 5 parts by weight.

The sealing agent for an organic EL display element of the present invention may contain a thermosetting agent. Examples of the thermosetting agent include hydrazide compounds, imidazole derivatives, acid anhydrides, dicyandiamides, guanidine derivatives, modified aliphatic polyamines, and addition products of various amines and epoxy resins.
Examples of the hydrazide compound include 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydrandine, sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, and malonic acid dihydrazide.
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) -adipamide, 2- Examples thereof include phenyl-4-methyl-5-hydroxymethylimidazole and 2-phenyl-4,5-dihydroxymethylimidazole.
Examples of the acid anhydride include tetrahydrophthalic anhydride and ethylene glycol-bis (anhydrotrimeritate).

Commercially available thermosetting agents include, for example, SDH (manufactured by Japan Finechem Co., Ltd.), ADH (manufactured by Otsuka Chemical Co., Ltd.), Amicure VDH, Amicure VDH-J, and Amicure UDH (all manufactured by Ajinomoto Fine-Techno). ) Etc. can be mentioned.

Regarding the content of the thermosetting agent, the preferable lower limit is 0.5 parts by weight and the preferable upper limit is 30 parts by weight with respect to 100 parts by weight of the curable resin. When the content of the thermosetting agent is 0.5 parts by weight or more, the obtained sealing agent for an organic EL display element becomes more excellent in thermosetting property. When the content of the thermosetting agent is 30 parts by weight or less, the obtained sealing agent for an organic EL display element is excellent in storage stability and barrier property. The more preferable lower limit of the content of the thermosetting agent is 1 part by weight, and the more preferable upper limit is 15 parts by weight.

The sealing agent for an organic EL display element of the present invention may contain a sensitizer. The sensitizer has a role of further improving the polymerization initiation efficiency of the photopolymerization initiator and further promoting the curing reaction of the encapsulant for an organic EL display element of the present invention.

Examples of the sensitizer include anthracene compounds such as 9,10-dibutoxyanthracene, thioxanthone compounds such as 2,4-diethylthioxanthone, and 2,2-dimethoxy-1,2-diphenylethane-1. -On, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoyl benzoate, 4,4'-bis (dimethylamino) benzophenone, 4-benzoyl-4'methyldiphenyl sulfide and the like can be mentioned.

The content of the sensitizer is preferably 0.05 parts by weight and a preferable upper limit is 3 parts by weight with respect to 100 parts by weight of the curable resin. When the content of the sensitizer is 0.05 parts by weight or more, the sensitizing effect is more exerted. When the content of the sensitizer is 3 parts by weight or less, light can be transmitted to a deep part without excessive absorption. The more preferable lower limit of the content of the sensitizer is 0.1 parts by weight, and the more preferable upper limit is 1 part by weight.

The encapsulant for an organic EL display element of the present invention preferably contains a stabilizer. By containing the above stabilizer, the sealing agent for an organic EL display element of the present invention becomes more excellent in storage stability.

Examples of the stabilizer include amine compounds such as benzylamine and aminophenol type epoxy resins.

The content of the stabilizer is preferably 0.001 part by weight and a preferable upper limit of 2 parts by weight with respect to 100 parts by weight of the curable resin. When the content of the stabilizer is in this range, the obtained sealing agent for an organic EL display element becomes more excellent in storage stability while maintaining excellent curability. The more preferable lower limit of the content of the stabilizer is 0.005 parts by weight, and the more preferable upper limit is 1 part by weight.

The sealing agent for an organic EL display element of the present invention may contain a silane coupling agent. The silane coupling agent has a role of improving the adhesiveness between the sealing agent for an organic EL display element of the present invention and a substrate or the like.

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

Regarding the content of the silane coupling agent, the preferable lower limit is 0.1 parts by weight and the preferable upper limit is 10 parts by weight with respect to 100 parts by weight of the curable resin. When the content of the silane coupling agent is within this range, it is more excellent in the effect of improving the adhesiveness of the obtained sealing agent for the organic EL display element while preventing the bleed-out of the excess silane coupling agent. It becomes. 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 sealing agent for an organic EL display element of the present invention may contain a surface modifier as long as the object of the present invention is not impaired. By containing the above-mentioned surface modifier, the flatness of the coating film can be imparted to the sealing agent for the organic EL display element of the present invention.
Examples of the surface modifier include surfactants and leveling agents.

Examples of the surface modifier include silicone-based, acrylic-based, and fluorine-based agents.
Commercially available surface modifiers include, for example, BYK-300, BYK-302, BYK-331 (all manufactured by Big Chemie Japan), UVX-272 (manufactured by Kusumoto Kasei Co., Ltd.), and Surflon. Examples thereof include S-611 (manufactured by AGC Seimi Chemical Co., Ltd.).

The sealant for an organic EL display element of the present invention may contain an ion exchange resin in order to improve the durability of the element electrode as long as the object of the present invention is not impaired.

As the ion exchange resin, any of a cation exchange type, an anion exchange type, and a biion exchange type can be used, and in particular, a cation exchange type or a biion exchange type capable of adsorbing chloride ions can be used. Is preferable.

The encapsulant for an organic EL display element of the present invention preferably does not contain a solvent from the viewpoint of further suppressing the generation of outgas. The sealant for an organic EL display element of the present invention can be excellent in coatability even if it does not contain the solvent.

Further, the encapsulant for an organic EL display element of the present invention is a curing retarder, a reinforcing agent, a softening agent, a plasticizer, a viscosity modifier, and an ultraviolet absorber, if necessary, as long as the object of the present invention is not impaired. , Various known additives such as antioxidants may be contained.

As a method for producing the sealant for an organic EL display element of the present invention, for example, a mixer such as a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, or a three-roll is used to obtain a curable resin. , A method of mixing the polymerization initiator, the water-absorbent filler according to the present invention, and an additive such as a silane coupling agent added as needed.

The encapsulant for an organic EL display element of the present invention is preferably a paste having a viscosity at 25 ° C. of 100 to 500 Pa · s using an E-type viscometer. When the paste has the above viscosity in this range, the sealant for an organic EL display element of the present invention is excellent in both coatability and dispersibility of the water-absorbent filler. The more preferable lower limit of the viscosity is 150 Pa · s, and the more preferable upper limit is 450 Pa · s. When a solvent is used to adjust the viscosity, it becomes difficult to suppress the generation of outgas.
For the above viscosity, for example, using VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer, the number of rotations of 1 to 100 rpm is appropriately adjusted from the optimum torque number in each viscosity region on the cone plate of CP1. Can be measured by selecting.

The shape of the sealing portion formed by the sealing agent for the organic EL display element of the present invention is not particularly limited as long as it can protect the laminated body having the organic light emitting material layer from the outside air. It may have a shape that completely covers the laminate, a closed pattern may be formed on the peripheral portion of the laminated body, or a pattern having a partially opened portion may be formed on the peripheral portion of the laminated body. You may. Among them, the sealing agent for an organic EL display element of the present invention can be suitably used for sealing the peripheral portion of the laminated body.

According to the present invention, it is possible to provide a sealant for an organic electroluminescent display element which has excellent barrier properties and can suppress panel peeling.

(A) is an SEM image of the surface of the water-absorbent filler A according to the present invention, and (b) is an SEM image of a cross section of the water-absorbent filler A according to the present invention. (A) is an SEM image of the surface of a commercially available water-absorbent filler (manufactured by Yoshizawa Lime Industry Co., Ltd., "quicklime J1P"), and (b) is a commercially available water-absorbent filler (manufactured by Yoshizawa Lime Industry Co., Ltd., "quicklime J1P"). ”) Is an SEM image of a cross section.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Examples 1 to 6, Comparative Example 1)
Example 1 by uniformly stirring and mixing each material at a stirring speed of 3000 rpm using a homodisper type stirring / mixing machine (“Homodisper L type” manufactured by Primix Corporation) according to the compounding ratios shown in Table 1. ~ 6, Sealing agent for organic EL display element of Comparative Example 1 was produced.
The "water-absorbent filler A according to the present invention" in the table has an average primary particle size of 3.5 μm measured using a dynamic light scattering type particle size measuring device, and has a specific surface area measured by a method according to JIS Z8807. Is 3.0 g / cm ³ , the average specific surface area measured by the BET method using nitrogen gas with a specific surface area measuring device is 11 m ² / g, and the water absorption rate is 25% by weight. ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) was used as the dynamic light scattering type particle size measuring device, and ASAP-2000 (manufactured by Shimadzu Corporation) was used as the specific surface area measuring device.
Further, in the table, "water-absorbent filler B according to the present invention" has an average primary particle size of 1.0 μm, a specific gravity of 2.8 g / cm ³ , and an average specific surface area measured in the same manner as the water-absorbent filler A. It is calcium oxide having a water absorption rate of 30% by weight and 18 m ^{2 / g.}
Further, "quick lime J1P (manufactured by Yoshizawa Lime Industry Co., Ltd.)" in the table has an average primary particle size of 3.0 μm, a specific gravity of 3.4 g / cm ³ , and an average specific surface area measured in the same manner as the water-absorbent filler A. Is 2.5 m ² / g and has a water absorption rate of 30% by weight.
An SEM image of the surface and cross section of the water-absorbent filler A according to the present invention is shown in FIG. As shown in FIG. 1, it was confirmed that the water-absorbent filler A according to the present invention has an uneven shape on the surface and has a large number of voids inside. In addition, SEM images of the surface and cross section of a commercially available water-absorbent filler (manufactured by Yoshizawa Lime Industry Co., Ltd., “quick lime J1P”) used in the comparative example are shown in FIG. As shown in FIG. 2, it was confirmed that the commercially available water-absorbent filler used in the comparative example had a flat surface and a flat cross section.

<Evaluation>
The following evaluations were carried out for each of the sealing agents for organic EL display elements obtained in Examples and Comparative Examples. The results are shown in Table 1.

(1) Viscosity Viscosity at 25 ° C. of each organic EL display element sealant obtained in Examples and Comparative Examples using an E-type viscometer (“VISCOMETER TV-22” manufactured by Toki Sangyo Co., Ltd.). Was measured.

(2) Barrier property The following Ca-TEST was performed on each of the sealants for organic EL display elements obtained in Examples and Comparative Examples.
First, a 30 mm × 30 mm glass substrate was covered with a mask having a plurality of 2 mm × 2 mm openings, and Ca was vapor-deposited by a vacuum vapor deposition machine. The vapor deposition conditions were such that the inside of the vapor deposition device of the vacuum vapor deposition apparatus ^{was depressurized to 2 × 10 -3} Pa to deposit 2000 Å of Ca at a vapor deposition rate of 5.0 Å / s. A glass substrate on which Ca is vapor-deposited is moved into a glove box controlled to a dew point (-60 ° C. or higher), and a glass substrate coated with a sealing agent for each organic EL display element obtained in Examples and Comparative Examples on the surface. Was pasted together. At this time, the vapor-deposited Ca was bonded so as to be present at positions 2 mm, 4 mm, and 6 mm from the end face of the glass substrate. Next, the sealing agent was cured by irradiating with ultraviolet rays of 365 nm at 3000 mJ / cm ² and further heating at 80 ° C. for 30 minutes to prepare a Ca-TEST substrate. The sealant for an organic EL display element obtained in Example 5 was cured by heating at 100 ° C. for 30 minutes to prepare a Ca-TEST substrate.
The obtained Ca-TEST substrate was exposed to a high temperature and high humidity condition of 85 ° C. and 85% RH, and the moisture infiltration distance was observed from the disappearance of Ca every hour. As a result, the moisture infiltration distance reached 6 mm. The barrier property was evaluated as "◯" when the time was 1000 hours or more, "Δ" when the time was 500 hours or more and less than 1000 hours, and "x" when the time was less than 500 hours.

(3) Adhesive state of the panel (manufacture of a substrate on which a laminate having an organic light emitting material layer is arranged)
A glass substrate (length 45 mm, width 45 mm, thickness 0.7 mm) formed by forming an ITO electrode with a thickness of 1000 Å was used as the substrate. The substrate is ultrasonically washed with acetone, an alkaline aqueous solution, ion-exchanged water, and isopropyl alcohol for 15 minutes each, then washed with boiled isopropyl alcohol for 10 minutes, and further, a UV-ozone cleaner (manufactured by Nippon Laser Electronics Co., Ltd.). Immediate treatment was performed with "NL-UV253").
Next, this substrate was fixed in the substrate folder of the vacuum vapor deposition apparatus, and 200 mg of N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine (α-NPD) was added to the unglazed crucible, and other differences. 200 mg of tris (8-quinolinolato) aluminum (Alq ₃ ) was placed in the unglazed crucible, and the pressure inside the vacuum chamber was reduced to ^{1 × 10 -4 Pa.} Then, the crucible containing α-NPD was heated, and α-NPD was deposited on the substrate at a vapor deposition rate of 15 Å / s to form a hole transport layer having a film thickness of 600 Å. Next, _{the crucible containing Alq 3} was heated to form an organic light emitting material layer having a film thickness of 600 Å at a vapor deposition rate of 15 Å / s. After that, the substrate on which the hole transport layer and the organic light emitting material layer were formed was transferred to another vacuum vapor deposition apparatus, and 200 mg of lithium fluoride was transferred to a tungsten resistance heating boat in this vacuum vapor deposition apparatus, and aluminum was transferred to another tungsten boat. 1.0 g of wire was put in. Then, the inside of the vapor deposition device of the vacuum vapor deposition apparatus is ^{depressurized to 2 × 10 -4} Pa to form 5 Å of lithium fluoride at a vapor deposition rate of 0.2 Å / s, and then 1000 Å of aluminum at a rate of 20 Å / s. bottom. The inside of the vapor deposition apparatus was returned to normal pressure with nitrogen, and a substrate on which a laminate having an organic light emitting material layer of 10 mm × 10 mm was arranged was taken out.

(Coating with Inorganic Material Membrane A)
A mask having an opening of 13 mm × 13 mm was placed on the substrate on which the obtained laminate was arranged so as to cover the entire laminate, and the inorganic material film A was formed by a plasma CVD method.
In the plasma CVD method, SiH ₄ gas and nitrogen gas are used as raw material gases, the respective flow rates are 10 sccm and 200 sccm, the RF power is 10 W (frequency 2.45 GHz), the chamber temperature is 100 ° C., and the chamber pressure is 0. The condition was 9 Torr.
The thickness of the formed inorganic material film A was about 1 μm.

(Formation of resin protective film)
The sealing agents for each organic EL display element obtained in Examples and Comparative Examples were applied to the substrate coated with the inorganic material film A so that the line width was 6 mm on the outer periphery, and the filler was put therein. .. After that, it is irradiated with ultraviolet rays having a wavelength of 365 nm using a high-pressure mercury lamp so that the irradiation amount is 3000 mJ / cm ^2, and further heated at 80 ° C. for 30 minutes to cure the sealing agent for the organic EL display element and to cure the resin protective film. Was formed. The sealant for an organic EL display element obtained in Example 5 was cured by heating at 100 ° C. for 30 minutes instead of irradiating with ultraviolet rays to form a resin protective film.

(Coating with Inorganic Material Membrane B)
After forming the resin protective film, a mask having an opening of 12 mm × 12 mm is installed so as to cover the entire resin protective film, and the inorganic material film B is formed by the plasma CVD method to form an organic EL display element. Obtained.
In the plasma CVD method, SiH ₄ gas and nitrogen gas are used as raw material gases, the respective flow rates are SiH ₄ gas 10 sccm and nitrogen gas 200 sccm, RF power is 10 W (frequency 2.45 GHz), chamber temperature is 100 ° C., and chamber. The procedure was carried out under the condition that the internal pressure was 0.9 Torr.
The thickness of the formed inorganic material film B was about 1 μm.

(Observation of panel adhesion)
The obtained organic EL display element was exposed to an environment of 85 ° C. and 85% RH for 2000 hours, and then the adhesive state of the panel was visually observed. The adhesive state of the panel was evaluated as "○" when there was no panel peeling, "Δ" when some panel peeling was confirmed, and "×" when most of the panel peeling was confirmed.

(4) Reliability of Organic EL Display Element The organic EL display element obtained in the same manner as in the above "(3) Panel adhesion state" is exposed to an environment of 85 ° C. and 85% RH for 2000 hours, and then 3V. The voltage of the above was applied, and the light emitting state (presence or absence of dark spots and quenching around the pixels) of the organic EL display element was visually observed. Organic EL display as "○" when there is no dark spot or peripheral quenching and uniform light emission, "△" when slight dark spot or peripheral quenching is observed, and "×" when the non-light emitting part is significantly enlarged. The reliability of the device was evaluated.

According to the present invention, it is possible to provide a sealant for an organic electroluminescent display element which has excellent barrier properties and can suppress panel peeling.

Claims (5)

It contains a curable resin, a polymerization initiator, and a water-absorbent filler (excluding calcium oxide particles having an alkoxide layer on the surface).
The water-absorbent filler has an average primary particle size of 5 μm or less, a specific gravity of 1.5 g / cm ³ or more, and 3.0 g / cm ³ or less.
The content of the water-absorbent filler is 5 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the curable resin . The sealant for an organic electroluminescent display element according to claim 1, wherein the water-absorbent filler is an oxide of an alkaline earth metal. The sealant for an organic electroluminescence display element according to claim 2, wherein the water-absorbent filler is calcium oxide. The sealant for an organic electroluminescent display element according to claim 1, 2 or 3, wherein the water-absorbent filler has an average specific surface area of 5 m ² / g or more and 20 m ^{2 / g or less.} The sealant for an organic electroluminescent display element according to claim 1, 2, 3 or 4 , wherein the polymerization initiator is a photopolymerization initiator.

Images