Sealant for organic electroluminescent display element, cured product thereof, and organic electroluminescent display device including the same

Abstract

To improve the discharging properties of an encapsulant in a step of manufacturing an organic EL display element.SOLUTION: There is provided an encapsulant for an organic electroluminescent display element which comprises (A) an acyclic alkanediol di(meth)acrylate having 6 or more carbon atoms, (B) a cyclic bifunctional (meth)acrylate having an alicyclic hydrocarbon group, (C) a cyclic (meth)acrylate having an aromatic ring, and (D) a photo-radical polymerization initiator, (E) a quinone-type stabilizer and (F) a stabilizer other than the component (E) and contains 70 to 80 pts.mass of the component (A), 14 to 24 pts.mass of the component (B), 4 to 8 pts.mass of the component (C), 2.5 to 3.5 pts.mass of the component (D), 100 to 300 ppm of the component (E) and 1850 to 2150 ppm of the component (F) based on the total 100 pts.mass of the component (A), the component (B) and the component (C).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a sealant for an organic electroluminescent display element and a cured product thereof. The present invention also relates to an organic electroluminescent display device containing the sealant. [Background technology]

[0002] Organic electroluminescence display devices (hereinafter also referred to as "organic EL display devices" or "OLED") have attracted attention due to their ability to emit light with high brightness. However, the organic EL elements in organic EL display devices are susceptible to degradation due to oxygen and moisture, which can lead to a decrease in light-emitting characteristics. To solve this problem, technologies for encapsulating organic EL elements to prevent degradation have been investigated. As an encapsulation technology, compounds known as organic EL display (OLED) encapsulants have been developed.

[0003] Patent Document 1 describes a sealant for organic EL devices that contains a polymerizable compound and a polymerization initiator, has a viscosity of 5 to 50 mPa·s at 25°C, a surface tension of 15 to 35 mN / m at 25°C, and has a water content of 1000 ppm or less at 25°C after being left to stand for 24 hours in an environment of 25°C and 50% RH.

[0004] Patent Document 2 describes a resin composition suitable for use as an encapsulant for organic EL devices, which contains a (meth)acrylate compound (A) having an aromatic hydrocarbon skeleton, a cyclic (meth)acrylate compound (B), and a polymerization initiator (C). Here, the cyclic (meth)acrylate compound (B) is at least one (meth)acrylate compound selected from the group consisting of (meth)acrylate compounds having an aromatic hydrocarbon skeleton, (meth)acrylate compounds having an alicyclic hydrocarbon skeleton, and (meth)acrylate compounds having a heterocyclic skeleton, which are (meth)acrylate compounds different from compound (A).

[0005] Current organic EL display devices are mainly divided into television sets and mobile devices, and the encapsulation methods are different for these. A method called the dam-fill method is used for television sets, which are stationary devices, while a method called thin-film encapsulation is used for mobile devices.

[0006] The dam-fill method, which uses two types of sealant, a dam agent and a fill agent, to prevent moisture penetration, is intended for organic EL elements that are mounted by sandwiching them between heavy glass substrates. These sealants are applied using a dispenser.

[0007] On the other hand, thin film encapsulation is a method that can accommodate the unique circumstances of mobile devices. That is, since the entire device needs to be thin and lightweight, a thin inorganic film (about 1 μm thick) is applied to the organic EL elements mounted on the substrate, and then a thin layer of encapsulant (about 4 to 8 μm thick) is precisely applied using an application device (such as an inkjet device), and the encapsulant is then encapsulated with an inorganic film about 1 μm thick on top of that (see Figure 1). The thin film encapsulation method aims not only to prevent moisture penetration, but also to flatten the unevenness of the substrate. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2019-040872 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-193970 [Patent Document 3] International Publication No. 2019 / 203071 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the above-mentioned conventional OLED encapsulants have problems that cannot be solved in thin film encapsulation methods for mobile applications. That is, even if the encapsulant is applied by ejecting it using an inkjet method, there is still room for improvement in the ejection properties, and problems such as nozzle clogging and poor flatness after application have arisen. Patent Document 3 describes a sealant for organic electroluminescence display elements that contains (A) an alkanediol di(meth)acrylate having from 4 to 20 carbon atoms and (B) a photopolymerization initiator, and in which the amount of hydrophilic functional groups per (meth)acrylate is in the range of 4.80 to 7.60 mmol / g. Patent Document 3 does not describe the present invention. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present invention can provide the following aspects.

[0011] (A) an acyclic alkanediol di(meth)acrylate having 6 or more carbon atoms; (B) a cyclic bifunctional (meth)acrylate having an alicyclic hydrocarbon group; (C) a cyclic (meth)acrylate having an aromatic ring; (D) a photoradical polymerization initiator; (E) a quinone-type stabilizer; (F) stabilizers other than the above (E) components Contains A sealant for an organic electroluminescence display element, comprising 70 to 80 parts by mass of component (A), 14 to 24 parts by mass of component (B), 4 to 8 parts by mass of component (C), 2.5 to 3.5 parts by mass of component (D), 100 ppm to 300 ppm of component (E), and 1850 ppm to 2150 ppm of component (F), relative to 100 parts by mass combined of component (A), component (B), and component (C).

[0012] The viscosity η of the sealant at 25°C C may be 10 mPa·s or more and 30 mPa·s or less.

[0013] The present invention also provides a cured product of the above sealant, and a sealant for an organic electroluminescence display device containing the cured product.

[0014] Furthermore, it is possible to provide a sealing material for an organic electroluminescence display element, which includes a laminate in which an inorganic film and an organic film containing the above-mentioned cured product are laminated.

[0015] Furthermore, an organic electroluminescent display device can be provided, which includes an organic electroluminescent display element and the above-mentioned sealing material for an organic electroluminescent display element. [Effects of the Invention]

[0016] According to the present invention, in the manufacturing process of an organic EL element, the dischargeability of the sealant from the coating device is improved, the flatness of the coating film after coating is improved, and as a result, the reliability of the organic EL element is also improved, which is a remarkable effect. [Brief explanation of the drawings]

[0017] [Figure 1] 1A to 1C are diagrams for explaining the steps of a thin film encapsulation method. DETAILED DESCRIPTION OF THE INVENTION

[0018] In the description of groups (atomic groups) in this specification, when a notation does not specify whether the group is substituted or unsubstituted, it encompasses both those that have no substituents and those that have a substituent. For example, the term "alkyl group" may encompass not only an alkyl group that has no substituents (unsubstituted alkyl groups) but also an alkyl group that has a substituent (substituted alkyl groups). The term "(meth)acrylic" in this specification represents a concept that encompasses both acrylic and methacrylic. The same applies to similar notations such as "(meth)acrylate." A bifunctional (meth)acrylate refers to a di(meth)acrylate.

[0019] Numerical ranges in this specification are inclusive of their upper and lower limits unless otherwise specified.

[0020] <Sealant for organic electroluminescence display elements> A sealant for an organic electroluminescent display element according to an embodiment of the present invention (hereinafter also simply referred to as "sealant") contains, as component (A), an acyclic alkanediol di(meth)acrylate having 6 or more carbon atoms, as component (B), a cyclic bifunctional (meth)acrylate having an alicyclic hydrocarbon group, as component (C), a cyclic (meth)acrylate having an aromatic ring, as component (C), and a photopolymerization initiator as component (D). Hereinafter, components (A), (B), and (C) are also collectively referred to as "polymerizable compounds."

[0021] The encapsulant is preferably used in thin film encapsulation methods in the manufacturing process of mobile devices.

[0022] The acyclic alkanediol di(meth)acrylate having 6 or more carbon atoms as component (A) refers to an acyclic alkanediol di(meth)acrylate having 6 or more carbon atoms in the alkanediol moiety. The alkanediol moiety may contain an ether bond. Component (A) is not particularly limited, but examples include the following. 1,6-Hexanediol di(meth)acrylate, 1,7-Heptanediol di(meth)acrylate, 1,8-Octanediol di(meth)acrylate, 1,9-Nonanediol di(meth)acrylate, 1,10-Decanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, 2,2-dimethyl-1,4-butanediol di(meth)acrylate, 1,12-Dodecanediol di(meth)acrylate, 7,7,9-trimethyl-3,13-dioxo-3,14-dioxa-5,12-diazahexadecane-1,16-diol di(meth)acrylate.

[0023] In the cyclic bifunctional (meth)acrylate having an alicyclic hydrocarbon group as component (B), the alicyclic hydrocarbon group may be a heterocycle containing a heteroatom or a ring having a substituent. Examples of component (B) include, but are not limited to, 1,4-cyclohexanediol di(meth)acrylate, dicyclopentadiene di(meth)acrylate, dicyclopentane di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, and tetrahydrofurfuryl di(meth)acrylate.

[0024] The aromatic ring-containing cyclic (meth)acrylate of component (C) is a compound having one or more (meth)acryloyl groups and one or more aromatic rings, and the aromatic rings may have other substituents. Component (C) is not particularly limited, but examples thereof include the following: Benzyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, ethoxylated-o-phenylphenol (meth)acrylate, bisphenol A di-(3-(meth)acryloxyethyl) ether, bisphenol A di-(3-(meth)acryloxy-2-hydroxypropyl) ether, 1,4-phenylene di(meth)acrylate, 1-phenyl-1,2-ethanediol di(meth)acrylate, polyoxyethyl-2,2-di(p-hydroxyphenyl)propane di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, tetrabromobisphenol A di-(3-(meth)acryloxy-2-hydroxypropyl) ether, tetrachlorobisphenol A di-(3-(meth)acryloxy-2-hydroxypropyl) ether.

[0025] The blending ratio of the above-mentioned polymerizable compounds is in the range of 70 to 80 parts by mass of component (A), 14 to 24 parts by mass of component (B), and 4 to 8 parts by mass of component (C), where the total of components (A), (B), and (C) is 100 parts by mass. In a preferred embodiment, the blending ratio may be in the range of 72 to 78 parts by mass of component (A), 15 to 22 parts by mass of component (B), and 5 to 8 parts by mass of component (C), where the total of components (A), (B), and (C) is 100 parts by mass, and more preferably in the range of 73 to 77 parts by mass of component (A), 15 to 20 parts by mass of component (B), and 5 to 8 parts by mass of component (C).

[0026] The encapsulant further contains a photoradical polymerization initiator (hereinafter sometimes referred to as photopolymerization initiator) as component (D), and the amount of component (D) is 2.5 to 3.5 parts by mass, preferably 2.6 to 3.4 parts by mass, and more preferably 2.7 to 3.3 parts by mass, based on 100 parts by mass of the total of components (A) to (C). By keeping the amount of component (D) within the above range, it is possible to obtain the effect of ensuring sufficient sensitivity / curing speed while also ensuring sufficient transparency of the encapsulant.

[0027] The component (D) is not particularly limited as long as it is a photopolymerization initiator that can polymerize the above-mentioned polymerizable compound.

[0028] Examples of the photoradical polymerization initiator include the following: benzophenone and its derivatives, benzil and its derivatives, anthraquinone and its derivatives, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzoin derivatives such as benzil dimethyl ketal, diethoxyacetophenone, acetophenone derivatives such as 4-tert-butyltrichloroacetophenone, 2-dimethylaminoethyl benzoate, p-dimethylaminoethyl benzoate, diphenyl disulfide, thioxanthone and its derivatives, camphorquinone, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxy-2-bromoethyl ester, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxy-2-methyl ester, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid chloride, etc. camphorquinone derivatives, α-aminoalkylphenone derivatives such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, benzoyldiethoxyphosphine oxide, 2,4,6-trimethylbenzoyldimethoxyphenylphosphine oxide, acylphosphine oxide derivatives such as 2,4,6-trimethylbenzoyldiethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, phenyl-glyoxylic acid-methyl ester, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester.

[0029] The photopolymerization initiators can be used alone or in combination of two or more.

[0030] As the photopolymerization initiator, an acylphosphine oxide derivative is preferred because it can be cured using only visible light of 390 nm or more and can be cured without damaging the organic EL device. Among the acylphosphine oxide derivatives, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (hereinafter also abbreviated as "TPO") is the most preferred because it can be cured using only light of 395 nm or more without reducing the transmittance of visible light when made into an organic EL display device. Examples of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide include "Omnirad TPO" manufactured by IGM Resins.

[0031] The sealant may or may not contain other components to adjust performance. Examples of other components include leveling agents, epoxy compounds, antioxidants, surfactants, sensitizers, etc. Among these, leveling agents are particularly preferred because they can flatten the coating surface in thin film encapsulation.

[0032] Any known leveling agent can be used, such as a fluorine-based compound, a silicone-based compound, or an acrylic compound. Specific examples of the leveling agent include poly(dibutyl fumarate) and organically modified polysiloxane. The amount of the leveling agent is preferably 0.1 to 5 parts by mass of component (D) when the total of components (A) to (C) is 100 parts by mass.

[0033] The sealing agent according to the present invention is further characterized by containing a quinone-type stabilizer as component (E) and a stabilizer other than the quinone-type stabilizer as component (F) in specific amounts. Hydroquinone is preferred as the quinone-type stabilizer. Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) is preferred as the stabilizer other than the quinone-type stabilizer.

[0034] The content of component (E) may be 100 ppm to 300 ppm, preferably 150 ppm to 300 ppm, and more preferably 200 ppm to 300 ppm, per 100 parts by mass of the total of components (A), (B), and (C). The content of component (F) may be 1850 ppm to 2150 ppm, preferably 1900 ppm to 2150 ppm, and more preferably 1950 ppm to 2150 ppm, per 100 parts by mass of the total of components (A), (B), and (C). Those skilled in the art who have read this specification will understand that the contents of components (E) and (F) can be adjusted by adjusting the selection of raw materials and the production process.

[0035] In this specification, the contents of the components (E) and (F) are measured by the following method. Measure 0.200 g of the sealant to be measured into a 20 mL volumetric flask and add acetone up to the target mark. Shake well to prepare a measurement sample. The measurement sample is then run through a gas chromatograph, and the concentration of specific components is quantified based on the peak position and peak area of ​​the resulting chart. The specifications of the gas chromatograph can be determined as appropriate, and the following can be used, for example: ·Equipment: Agilent 7890B Col.: HP-5MS 60m x φ0.25mm x film thickness 0.25μm Col.Temp.: 40℃ for 1 minute, then increase the temperature to 180℃ at a rate of 20℃ / min, then increase the temperature to 300℃ at a rate of 10℃ / min, and hold for 50 minutes. Injection temperature: 300℃ Det.Temp.:300℃ Flow: 1 mL / min x 22 min, then 0.1 mL / min, then 2 mL / min, split 1 / 20 Inj: 1μL

[0036] In a preferred embodiment, the water concentration of the sealant may be 1 ppm or more and 50 ppm or less, more preferably 3 ppm or more and 40 ppm or less, and even more preferably 5 ppm or more and 30 ppm or less. By satisfying the water concentration requirement, the effect of further improving the reliability of the organic EL element can be obtained.

[0037] In a preferred embodiment, the viscosity of the sealant may be 10 mPa·s or more and 30 mPa·s or less, more preferably 15 mPa·s or more and 25 mPa·s or less. Having a sealant with a viscosity in this range improves the ease of ejection when using an inkjet method, the ease of film formation, and other advantages. The viscosity of the sealant can be measured, for example, using a cone-plate viscometer (manufactured by Eiko Seiki Co., Ltd., product number HB DV3T, etc.) at 25°C and 200 to 250 rpm (preferably 250 rpm).

[0038] The method for producing a sealant according to the present invention includes a step of mixing appropriate amounts of a polymerizable compound and a photopolymerization initiator to obtain a mixture. The mixing method is not particularly limited, and stirring can be performed using a known stirrer. The production method also includes a step of filtering the mixture obtained by stirring using an appropriate filter. While there are no particular limitations on the filters that can be used for filtration, it is preferable to use a filter with a pore size of 1 μm or less to meet the specifications required for sealing OLEDs.

[0039] <Cured body, encapsulant, organic EL display device> In one embodiment of the present invention, a cured product obtained by irradiating the sealant with light can be provided. In another embodiment, a sealant for an organic electroluminescence display device can be provided, which includes a laminate in which an inorganic film and a cured product of the sealant are laminated (please note that in this specification, the terms "sealant" and "sealing material" are distinguished).

[0040] In still another embodiment, an organic EL display device can be provided that can be produced by sealing an organic EL element with the above-mentioned sealing material.

[0041] The light source for curing the sealant is not particularly limited, and examples thereof include a halogen lamp, a metal halide lamp, a high-power metal halide lamp (containing indium or the like), a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a xenon excimer lamp, a xenon flash lamp, and an LED.

[0042] The light irradiation dose from the light source is 100 mJ / cm 2 More than 8000mJ / cm 2 Preferably, it is 300 mJ / cm or less. 2 More than 2000mJ / cm 2 It is more preferable that the irradiation dose is 100 mJ / cm. 2 By setting the irradiation dose to 8000 mJ / cm or more, the sealant is sufficiently cured and sufficient sealing properties are easily obtained. 2 By setting the following, it is possible to obtain an effect of suppressing damage to the organic EL element.

[0043] For example, an organic EL display device can be manufactured by (i) forming a film (uncured film) of the sealant on the surface of a substrate on which an organic EL element is provided, and (ii) irradiating the film with light. This allows the organic EL element to be sealed with a cured product of the sealant, thereby improving the reliability of the final organic EL display device. After step (ii) above, an inorganic protective film such as SiN may be further provided on the surface of the cured product.

[0044] The film formation step (i) above preferably employs an inkjet method. In the manufacture of organic EL display devices, film formation by an inkjet method is preferred because it is necessary to uniformly form a film on a large-area substrate on which multiple organic EL elements are provided. In the film formation step (i) above, the film thickness is, for example, 1 μm or more and 10 μm or less, preferably 3 μm or more and 9 μm or less. By forming and curing a film of 1 μm or more, it is easy to obtain sufficient sealing performance as a sealant. Furthermore, a film thickness of 10 μm or less leads to miniaturization of organic EL display devices and reduction in manufacturing costs.

[0045] Hereinafter, one aspect of an organic EL display device manufactured using the sealant according to an embodiment will be described using a top-emission organic EL display device as an example. Note that the organic EL display device to which the sealant is applied is not limited to the top-emission type, and may be, for example, a bottom-emission organic EL display device in which light generated in the organic EL layer is irradiated from the substrate side.

[0046] A top-emission organic EL display device includes an organic EL element, a sealing layer that seals the organic EL element, and a sealing substrate provided on the sealing layer.

[0047] An organic EL element has a structure in which, for example, an anode, an organic EL layer including a light-emitting layer, and a cathode are laminated in this order on a substrate.

[0048] Examples of the substrate for the organic EL element include a glass substrate, a silicon substrate, a plastic substrate, etc. Among these, a glass substrate and a plastic substrate are preferred, and a glass substrate is more preferred.

[0049] As the plastic used for the plastic substrate, one or more selected from the group consisting of polyimide, polyetherimide, polyethylene terephthalate, polyethylene naphthalate, polyoxadiazole, aromatic polyamide, polybenzimidazole, polybenzobisthiazole, polybenzoxazole, polythiazole, and polyparaphenylene vinylene are preferred in terms of low moisture permeability, low oxygen permeability, and excellent heat resistance, and one or more selected from the group consisting of polyimide, polyetherimide, polyethylene terephthalate, and polyethylene naphthalate are more preferred in terms of high transmittance to energy rays such as ultraviolet rays and visible light.

[0050] The anode generally uses a conductive metal oxide film or a semitransparent metal thin film with a relatively large work function (preferably one with a work function greater than 4.0 eV). Examples of anode materials include metal oxides such as indium tin oxide (ITO) and tin oxide, metals such as gold (Au), platinum (Pt), silver (Ag), and copper (Cu), or alloys containing at least one of these metals, and organic transparent conductive films such as polyaniline or its derivatives, polythiophene or its derivatives, etc.

[0051] The anode can be formed of two or more layers if necessary. The thickness of the anode can be appropriately selected taking into consideration the electrical conductivity (and light transmittance in the case of a bottom-emission type). The thickness of the anode is preferably 10 nm to 10 μm, more preferably 20 nm to 1 μm, and most preferably 50 nm to 500 nm. Methods for producing the anode include vacuum deposition, sputtering, ion plating, and plating. In the case of a top-emission type, a reflective film may be provided under the anode to reflect light irradiated toward the substrate.

[0052] The organic EL layer includes at least a light-emitting layer made of an organic material. This light-emitting layer contains a light-emitting material. Examples of the light-emitting material include organic materials (low-molecular compounds or high-molecular compounds) that emit fluorescence or phosphorescence. The light-emitting layer may further contain a dopant material.

[0053] Examples of the organic material include dye-based materials, metal complex-based materials, and polymer materials. The dopant material is doped into the organic material for the purpose of improving the luminous efficiency of the organic material, changing the luminous wavelength, etc. The thickness of the luminescent layer made of these organic materials and the dopant added as needed is usually 2 nm or more and 200 nm or less.

[0054] Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, triphimanylamine derivatives, oxadiazole dimers, and pyrazoline dimers.

[0055] Examples of metal complex materials include metal complexes that emit light from triplet excited states, such as iridium complexes and platinum complexes, as well as aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyl zinc complexes, porphyrin zinc complexes, and europium complexes. Metal complexes include those having rare earth metals such as terbium (Tb), europium (Eu), and dysprosium (Dy), aluminum (Al), zinc (Zn), and beryllium (Be) as central metals, and those having oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, and quinoline structures as ligands. Among these, metal complexes having aluminum (Al) as the central metal and quinoline structures as ligands are preferred. Among metal complexes having aluminum (Al) as the central metal and quinoline structures as ligands, tris(8-hydroxyquinolinato)aluminum is preferred.

[0056] Examples of polymeric materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized versions of the above-mentioned colorants and metal complex luminescent materials.

[0057] Among the above-mentioned light-emitting materials, materials that emit blue light include distyrylarylene derivatives, oxadiazole derivatives, polyvinylcarbazole derivatives, polyparaphenylene derivatives, polyfluorene derivatives, and polymers thereof. Among these, polymer materials are preferred. Among polymer materials, one or more selected from the group consisting of polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.

[0058] Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and polymers thereof. Among these, polymer materials are preferred. Among polymer materials, one or more selected from the group consisting of polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.

[0059] Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyfluorene derivatives, and polymers thereof. Among these, polymer materials are preferred. Among polymer materials, one or more selected from the group consisting of polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferred.

[0060] Examples of dopant materials include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squarium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, and phenoxazone.

[0061] In addition to the light-emitting layer, the organic EL layer may appropriately include a layer provided between the light-emitting layer and the anode and a layer provided between the light-emitting layer and the cathode. First, examples of the layer provided between the light-emitting layer and the anode include a hole injection layer that improves the efficiency of hole injection from the anode, and a hole transport layer that transports holes injected from the anode or the hole injection layer to the light-emitting layer. Examples of the layer provided between the light-emitting layer and the cathode include an electron injection layer that improves the efficiency of electron injection from the cathode, and an electron transport layer that transports electrons injected from the cathode or the electron injection layer to the light-emitting layer.

[0062] Examples of materials for forming the hole injection layer include phenylamines such as 4',4''-tris{2-naphthyl(phenyl)amino}triphenylamine, starburst amines, phthalocyanines, oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, amorphous carbon, polyaniline, and polythiophene derivatives.

[0063] Examples of materials that can be used to form the hole transport layer include polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, polysiloxane derivatives having an aromatic amine in the side chain or main chain, pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, benzidine derivatives, polyaniline or a derivative thereof, polythiophene or a derivative thereof, polyarylamine or a derivative thereof, polypyrrole or a derivative thereof, poly(p-phenylenevinylene) or a derivative thereof, and poly(2,5-thienylenevinylene) or a derivative thereof.

[0064] When these hole injection layers or hole transport layers have the function of blocking the transport of electrons, they are sometimes called electron blocking layers.

[0065] Materials constituting the electron transport layer include oxadiazole derivatives, anthraquinodimethane or its derivatives, benzoquinone or its derivatives, naphthoquinone or its derivatives, anthraquinone or its derivatives, tetracyanoanthraquinodimethane or its derivatives, fluorenone derivatives, diphenyldicyanoethylene or its derivatives, diphenoquinone derivatives, 8-hydroxyquinoline or its derivatives, polyquinoline or its derivatives, polyquinoxaline or its derivatives, and polyfluorene or its derivatives. Derivatives include metal complexes. Of these, 8-hydroxyquinoline or its derivatives are preferred. Among 8-hydroxyquinoline or its derivatives, tris(8-hydroxyquinolinato)aluminum is preferred because it can also be used as a fluorescent or phosphorescent organic material contained in the light-emitting layer.

[0066] The electron injection layer may be a single-layer structure of calcium (Ca), a single-layer structure of a layer made of one or more metals selected from the group consisting of metals in Groups IA and IIA of the periodic table and having a work function of 1.5 to 3.0 eV, and their oxides, halides, and carbonates, or a laminate structure of a Ca layer and a layer made of one or more metals in Groups IA and IIA of the periodic table and having a work function of 1.5 to 3.0 eV, and their oxides, halides, and carbonates. Examples of metals in Group IA of the periodic table and having a work function of 1.5 to 3.0 eV, or their oxides, halides, and carbonates, include lithium (Li), lithium fluoride, sodium oxide, lithium oxide, and lithium carbonate. Examples of metals in Group IIA of the periodic table having a work function of 1.5 eV to 3.0 eV or oxides, halides, and carbonates thereof include strontium (Sr), magnesium oxide, magnesium fluoride, strontium fluoride, barium fluoride, strontium oxide, and magnesium carbonate.

[0067] When the electron transport layer or the electron injection layer has a function of blocking the transport of holes, the electron transport layer or the electron injection layer is sometimes called a hole blocking layer.

[0068] The cathode is preferably a transparent or semi-transparent material that has a relatively small work function (preferably less than 4.0 eV) and allows easy electron injection into the light-emitting layer. Examples of cathode materials include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), aluminum (Al), scandium (Sc), vanadium (V), zinc (Zn), yttrium (Y), indium (In), cerium (Ce), samarium (Sm), europium (Eu), and terbium (Tb). Examples of the metal include metals such as ytterbium (Yb), ytterbium (Yb), alloys of two or more of the above metals, alloys of one or more of the above metals and one or more of gold (Au), silver (Ag), platinum (Pt), copper (Cu), chromium (Cr), manganese (Mn), titanium (Ti), cobalt (Co), nickel (Ni), tungsten (W), and tin (Sn), graphite or graphite intercalation compounds, and metal oxides such as ITO and tin oxide.

[0069] The cathode may have a laminated structure of two or more layers. Examples of the laminated structure of two or more layers include a laminated structure of the above-mentioned metals, metal oxides, fluorides, or alloys thereof with metals such as Al, Ag, or Cr. The thickness of the cathode can be appropriately selected taking into consideration electrical conductivity and durability. The thickness of the cathode is preferably 10 nm or more and 10 μm or less, more preferably 15 nm or more and 1 μm or less, and most preferably 20 nm or more and 500 nm or less. Methods for producing the cathode include vacuum deposition, sputtering, and lamination in which a metal thin film is thermocompression bonded.

[0070] The layers provided between the light-emitting layer and the anode, and between the light-emitting layer and the cathode can be appropriately selected depending on the performance required for the organic EL display device to be manufactured. For example, the organic EL element can have any of the layer configurations (i) to (xv) below. (i) Anode / hole transport layer / light-emitting layer / cathode (ii) Anode / Emitting Layer / Electron Transport Layer / Cathode (iii) Anode / hole transport layer / light-emitting layer / electron transport layer / cathode (iv) Anode / hole injection layer / light-emitting layer / cathode (v) Anode / Emitting layer / Electron injection layer / Cathode (vi) Anode / hole injection layer / light-emitting layer / electron injection layer / cathode (vii) Anode / hole injection layer / hole transport layer / light-emitting layer / cathode (viii) Anode / hole transport layer / light-emitting layer / electron injection layer / cathode (ix) Anode / hole injection layer / hole transport layer / light-emitting layer / electron injection layer / cathode (x) Anode / hole injection layer / light-emitting layer / electron transport layer / cathode (xi) Anode / Emitting layer / Electron transport layer / Electron injection layer / Cathode (xii) Anode / hole injection layer / light-emitting layer / electron transport layer / electron injection layer / cathode (xiii) Anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / cathode (xiv) Anode / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode (xv) Anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode (The symbol " / " above indicates that each layer is stacked adjacently. The same applies below.)

[0071] The sealing layer is provided to prevent gases such as water vapor and oxygen from coming into contact with the organic EL device. The sealing layer is formed by alternately forming inorganic films and organic films from the bottom up. The inorganic / organic laminate may be formed two or more times.

[0072] The inorganic film of the inorganic / organic laminate is a film provided to prevent the organic EL element from being exposed to gases such as water vapor and oxygen present in the environment in which the organic EL display device is placed. This inorganic film is preferably a continuous, dense film with few defects such as pinholes. Examples of inorganic films include single films such as SiN film, SiO film, SiON film, Al2O3 film, and AlN film, as well as laminated films of these films.

[0073] The organic film of the inorganic / organic laminate is provided to cover defects such as pinholes formed on the inorganic film and to provide a flat surface. The organic film is preferably formed in an area narrower than the area where the inorganic film is formed. This is because if the organic film is formed in the same area as or wider than the area where the inorganic film is formed, the exposed area of ​​the organic film will deteriorate. However, the top organic film formed on the top layer of the entire sealing layer is formed in approximately the same area as the area where the inorganic film is formed. It is formed so as to flatten the top surface of the sealing layer. The organic film may be a film formed from the present sealant (i.e., a film including a cured product of the sealant). The organic film can be formed quickly and uniformly by inkjet coating.

[0074] Counting the inorganic / organic laminate as one set, it is preferable to provide one to five sets of sealing layers. This is because when there are six or more sets of inorganic / organic laminates, the sealing effect on the organic EL device is approximately the same as when there are five sets. The thickness of the inorganic film of the inorganic / organic laminate is preferably 50 nm or more and 1 μm or less. The thickness of the organic film of the inorganic / organic laminate is preferably 1 μm or more and 15 μm or less, and more preferably 3 μm or more and 10 μm or less. When the organic film is 1 μm or more thick, particles generated during device formation can be completely covered and the film can be applied to the inorganic film with good flatness. When the organic film is 15 μm or less thick, moisture does not penetrate from the side of the organic film, further improving the reliability of the organic EL display device.

[0075] The sealing substrate is formed in close contact with the sealing layer so as to cover the entire upper surface of the uppermost organic film. Examples of this sealing substrate include the above-mentioned substrates. Among these, a substrate transparent to visible light is preferred. Among substrates transparent to visible light (transparent sealing substrates), one or more selected from the group consisting of glass substrates and plastic substrates are preferred, and a glass substrate is more preferred.

[0076] The thickness of the transparent sealing substrate is preferably 1 μm to 1 mm, more preferably 10 μm to 800 μm, and most preferably 50 μm to 300 μm. By providing the transparent sealing substrate above the sealing layer, deterioration that occurs when the surface of the top organic film comes into contact with gas can be suppressed. This further improves the barrier properties of the organic EL display device.

[0077] Next, a method for manufacturing an organic EL display device having the above-described configuration will be described. First, an anode patterned into a predetermined shape by a known method, an organic EL layer including an emitting layer, and a cathode are formed in this order on a first substrate to form an organic EL element. For example, when the organic EL display device is used as a dot matrix display device, banks are formed to separate the emitting regions into a matrix, and the organic EL layer including the emitting layer is formed in the region surrounded by these banks.

[0078] Next, a first inorganic film having a predetermined thickness is formed on the substrate on which the organic EL element is formed by a film formation method such as a PVD (Physical Vapor Deposition) method such as a sputtering method or a CVD method such as a plasma CVD (Chemical Vapor Deposition) method.

[0079] The sealant is then applied to the first inorganic film using a coating film formation method such as solution coating or spray coating, or a flash vapor deposition method, inkjet method, or the like (the inkjet method is preferred from the viewpoint of productivity). The sealant is then cured by irradiation with energy rays such as ultraviolet light or visible light, forming a first organic film. Through these steps, one set of inorganic / organic laminate is formed.

[0080] The above-described process for forming an inorganic / organic laminate is repeated a predetermined number of times. However, for the final set, i.e., the uppermost inorganic / organic laminate, a sealant may be applied to the top surface of the inorganic film by coating, flash evaporation, inkjet printing, or the like to flatten the top surface.

[0081] Next, a transparent sealing substrate is bonded to the surface of the substrate to which the sealant has been attached. The bonding is performed by aligning the substrate. Thereafter, energy rays are irradiated from the transparent sealing substrate side to harden the sealant present between the top inorganic film and the transparent sealing substrate. The sealant is thus hardened, forming the top organic film and bonding the top organic film to the transparent sealing substrate. This completes the method for manufacturing an organic EL display device.

[0082] After the sealant is applied to the inorganic film, the sealant may be partially irradiated with energy rays to polymerize it. This makes it easier to prevent the shape of the top organic film from being distorted when a transparent sealing substrate is placed on it. The thicknesses of the inorganic film and the organic film may be the same for each inorganic / organic laminate, or may be different for each inorganic / organic laminate.

[0083] The organic EL display device described above may be a surface light source, a segment display device, a dot matrix display device, or the like.

[0084] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0085] The embodiments of the present invention will be described in detail based on examples and comparative examples, but the present invention is not limited to the examples.

[0086] <Sealant manufacturing> The following raw materials were used: 1,12-Dodecanediol dimethacrylate: Arkema, product name "SR262" Ethoxylated bisphenol A dimethacrylate (m + n = 4), ethylene oxide unit = 4 mol: Shin-Nakamura Chemical Co., Ltd., product name "BPE200" Ethoxylated o-phenylphenol acrylate: Shin-Nakamura Chemical Co., Ltd., product name "A-LEN-10" Dimethylol-tricyclodecane dimethacrylate: manufactured by Shin-Nakamura Chemical Co., Ltd., product name "ADCP" 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide: IGM Resins, trade name "TPO" Hydroquinone (stabilizer): commercially available Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (stabilizer): commercially available product Polydibutyl fumarate: commercially available

[0087] (Examples 1 and 2) Each sealing agent was produced according to the following procedure using the polymerizable compound and photopolymerization initiator shown in Table 1. The unit of component amount in Table 1 is parts by mass unless otherwise specified.

[0088] Mixing process The polymerizable compound, photopolymerization initiator, leveling agent, and stabilizer were weighed out in the amounts (unit: parts by mass) listed in Table 1 and stirred using a stirrer (Three-One Motor) at 200 rpm and 23°C for 3 hours. This resulted in a mixture. 10% by mass of a dehydrating agent (molecular sieve 5A) was added to the resulting mixture, and the mixture was allowed to stand at 23°C for 72 hours in an environment with a dew point of -70°C or less. To promote dehydration, the mixture was gently shaken by hand once every 24 hours. The mixture was then bubbled with nitrogen gas at 1000 Pa or less for 30 minutes or more.

[0089] Filtration process The mixture that had undergone the mixing step was filtered through a filter with a pore size of 1 μm or less to remove foreign matter. In this way, the sealant according to the example was produced.

[0090] (Comparative Example 1) A sealant was produced in the same manner as in Example 1, except that no stabilizer was added in the mixing step.

[0091] (Comparative Example 2) A sealant was produced in the same manner as in Example 2, except that no stabilizer was added in the mixing step.

[0092] (viscosity) The viscosity of each of the sealants of the Examples and Comparative Examples was measured using a cone-plate viscometer (manufactured by Eiko Seiki Co., Ltd., HB DV3T, cone plate: CPA-40Z) at 25° C. and 250 rpm.

[0093] (Evaluation of the percentage of defective nozzles during inkjet ejection) The inkjet cartridges were filled with sealant immediately after manufacture and after heating at 80°C for 16 hours (after high-temperature treatment), and the ejection status of all 16 nozzles was checked to determine the percentage of nozzles that had ejection problems. The discharge conditions were set as follows: Inkjet device: Fujifilm DMP2850 Inkjet conditions: 23°C, air, clean room (class 1000), under yellow lamp ·Discharge speed: 6.5m / s (±0.1) Discharge voltage: Adjust the discharge voltage so that the discharge speed is 6.5 m / s (±0.1). ·Discharge temperature: 35℃ Observation of the ejection status: The ejection status of all 16 nozzles was checked, and ejection defects were determined to occur when there was a flight deflection of 5° or more, a drop in ejection speed of 0.5 m / s or more, or no ejection.

[0094] (Reliability evaluation of organic EL display devices (organic EL reliability)) - Fabrication of organic EL display elements for evaluation A 30 mm square glass substrate (700 μm thick) with an ITO electrode was washed with acetone and then isopropanol. The following compounds were then sequentially deposited by vacuum deposition to form thin films, resulting in a substrate with a 2 mm square organic EL element consisting of an anode, hole injection layer, hole transport layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, and cathode. The composition of each layer is as follows: Anode (ITO): 150nm / polymer Hole injection layer (polymer HIL): 60 nm Hole transport layer (N,N'-di-1-naphthyl-N,N'-diphenylbenzidine; α-NPD): 30 nm Light-emitting layer (tris(2-phenylpyridine)iridium(III); Ir(ppy)3 + 4,4'-bis(9H-carbazol-9-yl)biphenyl; CBP[6%]): 30 nm Hole blocking layer (bis(2-methyl-8-quinolinolato)-4-(phenylphenolato)aluminum; BAlq): 10 nm Electron transport layer (tris(8-quinolinolato)aluminum; Alq3): 30 nm Electron injection layer (LiF): 0.8nm Cathode (MgAg / IZO): 10nm / 100nm

[0095] Next, each sealant was applied to a 2mm x 2mm organic EL element in a nitrogen atmosphere using a Fujifilm inkjet device (product number: DMP2850), to obtain a 10μm thick photosensitive resin film. After that, in a N2 environment, an LED lamp (HOYA UV-LED LIGHT SOURCE H-4MLH200-V1) emitting light with a wavelength of 395nm was used to apply a cumulative light dose of 1,500mJ / cm2 at a wavelength of 395nm to the photosensitive film. 2 The coating was irradiated with light under the following conditions: A cured film was obtained.

[0096] A mask (cover) with an opening of 10 mm x 10 mm was placed so as to cover the entire cured film obtained, and a SiN film was formed by plasma CVD. The thickness of the formed SiN (inorganic film) was about 1 μm. In this way, an organic EL device was obtained.

[0097] The obtained organic EL element was attached to a 30 mm × 30 mm × 0.7 mm alkali-free glass (Eagle XG manufactured by Corning) using a 30 mm × 30 mm × 25 μm transparent substrate-less double-sided tape, thus producing an organic EL display device for evaluation.

[0098] Reliability testing The organic EL display device for evaluation obtained as described above was subjected to a high-temperature, high-humidity environment of 85°C and 85% RH for 500 hours. Before and after this high-temperature, high-humidity treatment, a current was passed through the organic EL display device for evaluation, and the light-emitting surface was photographed. The photographed images (before and after the high-temperature, high-humidity treatment) were analyzed using Innotek's image analysis software "Quick Grain" to determine the light-emitting area. The reduction rate (%) of the light-emitting area before and after the high-temperature, high-humidity treatment was then calculated.

[0099] Information regarding the Examples and Comparative Examples is summarized in the table below.

[0100] [Table 1]

[0101] As shown in the table above, the reliability of the organic EL display device manufactured using the sealant according to the example of the present invention was good. On the other hand, in the comparative example, although there was no problem with the initial dischargeability, the dischargeability became very poor after high-temperature treatment, and the reliability test could not be carried out.

Claims

1. (A) an acyclic alkanediol di(meth)acrylate having 6 or more carbon atoms; (B) a cyclic bifunctional (meth)acrylate having an alicyclic hydrocarbon group; (C) a cyclic (meth)acrylate having an aromatic ring; (D) a photoradical polymerization initiator; (E) a quinone-type stabilizer; (F) a stabilizer other than the above component (E); Contains A sealant for an organic electroluminescence display element, comprising, relative to 100 parts by mass of the total of the components (A), (B), and (C), 70 to 80 parts by mass of the component (A), 14 to 24 parts by mass of the component (B), 4 to 8 parts by mass of the component (C), 2.5 to 3.5 parts by mass of the component (D), 100 ppm to 300 ppm of the component (E), and 1850 ppm to 2150 ppm of the component (F).

2. Viscosity η at 25 ° C. C 2. The sealant for an organic electroluminescence display element according to claim 1, wherein the viscosity is 10 mPa·s or more and 30 mPa·s or less.

3. A cured product obtained by curing the sealant according to any one of claims 1 and 2.

4. A sealing material for an organic electroluminescence display device, comprising the cured product according to claim 3 .

5. It includes a laminate in which an inorganic film and an organic film are laminated, A sealing material for an organic electroluminescence display element, wherein the organic film comprises the cured product according to claim 3 .

6. An organic electroluminescent display device comprising: an organic electroluminescent display element; and the sealing material for an organic electroluminescent display element according to claim 4 or 5.

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