Sealing agent for organic electroluminescent display element

Abstract

A sealant for an organic electroluminescent display element, which contains: (A) an alkylene glycol di(meth)acrylate having a carbon number of 4 or more and 20 or less, and (B) a photopolymerization initiator, the amount of a hydrophilic functional group with respect to the (meth)acrylate being in the range of 4.80 to 7.60 mmol / g.

Description

Technical Field

[0001] This invention relates to sealants for organic electroluminescent display elements. Background Technology

[0002] Organic electroluminescent (EL) devices (also known as OLED devices) have attracted attention as devices capable of emitting high-brightness light. However, OLED devices suffer from degradation due to oxygen and moisture, resulting in reduced light-emitting characteristics.

[0003] To address this problem, techniques for sealing organic EL elements to prevent degradation caused by moisture have been investigated. For example, a method of sealing with a sealing material containing powdered glass can be cited (see Patent Document 1).

[0004] The following are proposed: an organic electroluminescent display element, characterized in that the sealing layer is a laminate in which at least a barrier layer, a resin layer, and a barrier layer are sequentially formed (see Patent Document 2); and an organic EL device, characterized in that it comprises: a sealing layer formed by alternating layers of inorganic and organic films for sealing the organic EL element; and a sealing glass substrate arranged in such a way that it is closely adhered to the uppermost organic film of the sealing layer to cover the entire upper surface of the uppermost organic film (see Patent Document 3).

[0005] The following are proposed: a sealant for organic electroluminescent display elements, wherein the resin composition used for sealing the organic EL element contains a cyclic ether compound, a cationic polymerization initiator, and a polyfunctional vinyl ether compound (see Patent Document 4); a cationic polymerizable resin composition containing a cationic polymerizable compound and a photocationic polymerization initiator or a thermal cationic polymerization initiator (see Patent Document 5). A (meth)acrylic acid resin composition is proposed as a resin composition for sealing organic EL elements (Patent Documents 6-14).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 10-74583

[0009] Patent Document 2: Japanese Patent Application Publication No. 2001-307873

[0010] Patent Document 3: Japanese Patent Application Publication No. 2009-37812

[0011] Patent Document 4: Japanese Patent Application Publication No. 2014-225380

[0012] Patent Document 5: Japanese Patent Application Publication No. 2012-190612

[0013] Patent Document 6: Japanese Patent Application Publication No. 2014-229496

[0014] Patent Document 7: Japanese Patent Application Publication No. 2014-196387

[0015] Patent Document 8: Japanese Patent Application Publication No. 2014-193970

[0016] Patent Document 9: Japanese Patent Application Publication No. 2014-193971

[0017] Patent Document 10: WO2014 / 157642

[0018] Patent Document 11: US2017 / 0062762

[0019] Patent Document 12: Japanese Patent Publication No. 2017-536429

[0020] Patent Document 13: Japanese Patent Publication No. 2018-504735

[0021] Patent Document 14: WO2016 / 068415 Summary of the Invention

[0022] The problem the invention aims to solve

[0023] However, the prior art described in the aforementioned documents has room for improvement in the following aspects.

[0024] In Patent Document 1, during mass production, a method is used to hold the organic EL element with a substrate with low water permeability, such as glass, and seal its outer periphery. However, this method has the following problem: the structure becomes a hollow sealed structure, thus failing to prevent moisture from seeping into the hollow sealed structure, leading to the deterioration of the organic EL element.

[0025] Patent documents 2 and 3 present the following problem: Since the organic film is formed by vapor deposition, the thickness of the organic film is less than 3 μm. When the thickness of the organic film is less than 3 μm, the following problems exist: it cannot completely cover the particles generated during device formation, and it is also difficult to coat the inorganic film while maintaining flatness.

[0026] Patent document 4 proposes a sealant using epoxy-based materials, but such materials require heating to cure, which can damage organic EL elements and lead to yield problems. Patent document 5 proposes a light-curing sealant using epoxy-based materials, but such materials require UV light for curing, which can damage organic EL elements due to UV light and also lead to yield problems.

[0027] Patent documents 6-10 and 12-14 describe the characteristics required for such sealing materials, including reducing water vapor permeability. However, they do not describe the problem of the sealing material itself penetrating through pinholes in the passivation film, which reduces the reliability of organic EL elements, or any countermeasures.

[0028] Patent document 11 describes the use of cyclic monofunctional (meth)acrylates, but it cannot solve the problem of unreacted substances becoming exhaust gas, resulting in poor light emission of organic EL elements.

[0029] As described above, the inability to balance inkjet ejection and the reliability of organic EL elements has always been a problem in the existing technology.

[0030] Solution for solving the problem

[0031] The present invention was made in view of the above circumstances, and its object is to provide, for example, a composition with excellent coatability and low moisture permeability when used for sealing organic EL elements.

[0032] That is, the following solutions can be provided in the embodiments of the present invention. [1]

[0034] A sealant for an organic electroluminescent display element, comprising: (A) an alkyl diol di(meth)acrylate with 4 or more carbon atoms and less than 20 carbon atoms, and (B) a photopolymerization initiator, wherein the amount of hydrophilic functional groups relative to the (meth)acrylate is in the range of 4.80 to 7.60 mmol / g. [2]

[0036] The sealant for organic electroluminescent display elements according to [1] further contains (C) methacrylate other than component (A), and contains 30 or more but less than 100 parts by mass of component (A), 0.05 to 6 parts by mass of component (B), and more than 0 parts by mass but less than 70 parts by mass of component (C) relative to a total of 100 parts by mass of components (A) and (C). [3]

[0038] According to the sealant for organic electroluminescent display elements described in [2], the amount of hydrophilic functional groups in component (C) relative to (meth)acrylate is 3.00 to 15.00 mmol / g. [4]

[0040] The sealant for organic electroluminescent display elements according to any one of [1] to [3] has a viscosity of 2 mPa·s or more and 50 mPa·s or less as measured by an E-type viscometer at 25°C. [5]

[0042] The sealant for organic electroluminescent display elements according to any one of [1] to [4], wherein the water content is 90 ppm or less. [6]

[0044] The sealant for organic electroluminescent display elements according to any one of [1] to [5], wherein the dissolved oxygen content is 1 ppm or more and 20 ppm or less. [7]

[0046] The sealant for organic electroluminescent display elements according to any one of [1] to [6], wherein it does not contain difunctional (meth)acrylate oligomers / polymers or polyfunctional (meth)acrylate oligomers / polymers. [8]

[0048] The sealant for organic electroluminescent display elements according to any one of [1] to [7], wherein component (A) is an alkyl diol di(meth)acrylate with 12 or more and 16 or less carbon atoms. [9]

[0050] The sealant for organic electroluminescent display elements according to any one of [1] to [8], wherein component (A) is 1,12-dodecanediol di(meth)acrylate.

[10]

[0052] The sealant for organic electroluminescent display elements according to any one of [2] to [9], wherein component (C) is one or more of the group consisting of alkyl (meth)acrylates having 8 or more carbon atoms, (meth)acrylates having alicyclic hydrocarbon groups, and (meth)acrylates having aromatic hydrocarbon groups.

[11]

[0054] The sealant for organic electroluminescent display elements according to any one of [2] to

[10] , wherein component (C) contains lauryl methacrylate.

[12]

[0056] The sealant for an organic electroluminescent display element according to any one of [2] to

[11] , wherein component (C) contains one or more of the group consisting of dicyclopentyl methacrylate, dicyclopentyloxyethyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate and dicyclopentyloxyethyl methacrylate.

[13]

[0058] The sealant for organic electroluminescent display elements according to any one of [2] to

[12] , wherein component (C) contains ethoxylated o-phenylphenol (meth) acrylate.

[14]

[0060] The sealant for organic electroluminescent display elements according to any one of [1] to

[13] , wherein component (B) is an acylphosphine oxide derivative.

[15]

[0062] A cured body is obtained by curing an organic electroluminescent display element as described in any one of [1] to

[14] with a sealant.

[16]

[0064] A bonding body is obtained by bonding an organic electroluminescent display element according to any one of [1] to

[14] with a sealant.

[17]

[0066] The curing method of the sealant for organic electroluminescent display elements according to any one of [1] to

[14] is characterized in that the curing is performed using a wavelength of 380 nm or more and 500 nm or less.

[18]

[0068] The curing method of the sealant for organic electroluminescent display elements according to any one of [1] to

[14] is characterized in that the curing is performed using an LED lamp with an emission wavelength of 395 nm.

[19]

[0070] The method for applying a sealant for an organic electroluminescent display element as described in any one of [1] to

[14] , wherein the coating is performed using an inkjet method.

[20]

[0072] An organic EL device comprising a sealant for an organic electroluminescent display element as described in any one of [1] to

[14] . [twenty one]

[0074] A display comprising a sealant for an organic electroluminescent display element as described in any one of [1] to

[14] .

[0075] The effects of the invention

[0076] The sealant of the present invention has the following effects: excellent ejection properties when using inkjet printing, and excellent reliability, coatability, and low moisture permeability of the resulting organic EL element. Detailed Implementation

[0077] The following describes this embodiment.

[0078] This embodiment relates to a sealant for organic electroluminescent display elements. This embodiment relates, for example, to a (meth)acrylic resin composition that can be used as a sealant for organic electroluminescent (EL) display elements.

[0079] Unless otherwise specified, the numerical ranges described in this specification include both upper and lower limits. Unless otherwise specified, the following definitions apply: "(meth)acrylate" refers to acrylate or methacrylate; "(meth)acryloyloxy," "(meth)acrylamide," etc., have the same meaning. "Monofunctional (meth)acrylate" refers to a (meth)acrylate with one (meth)acryloyl group; "difunctional (meth)acrylate" refers to a (meth)acrylate with two (meth)acryloyl groups. "Polyfunctional (meth)acrylate" refers to a (meth)acrylate with three or more (meth)acryloyl groups, excluding difunctional (meth)acrylates.

[0080] The following description uses a top-emitting organic EL device that emits light from the side opposite to the substrate of an organic EL element formed on a substrate as an example. The top-emitting organic EL device has a structure in which the following parts are sequentially formed on a substrate: an organic EL element, which is formed by stacking an anode, an organic EL layer including a light-emitting layer, and a cathode in sequence; a sealing layer, which includes a laminate of an inorganic film and an organic film covering the entire organic EL element; and a sealing substrate disposed on the sealing layer.

[0081] Various substrates, such as glass substrates, silicon substrates, and plastic substrates, can be used as substrates. Among these, one or more substrates composed of glass substrates and plastic substrates are preferred, and glass substrates are more preferred.

[0082] Examples of plastics used as plastic substrates include polyimide, polyetherimide, polyethylene terephthalate, polyethylene naphthalate, polyoxadiazole, aromatic polyamide, polybenzimidazole, polybenzobisthiazole, polybenzoxazole, polythiazole, poly(p-phenylene vinylene), polymethyl methacrylate, polystyrene, polycarbonate, polycyclic olefins, and polyacrylic acid. Among these, from the perspective of low moisture permeability, low oxygen permeability, and excellent heat resistance, one or more of the following are preferred: polyimide, polyetherimide, polyethylene terephthalate, polyethylene naphthalate, polyoxadiazole, aromatic polyamide, polybenzimidazole, polybenzobisthiazole, polybenzoxazole, polythiazole, and poly(p-phenylenevinylene). From the perspective of high transmittance of high-energy rays such as ultraviolet or visible light, one or more of the following are preferred: polyimide, polyetherimide, polyethylene terephthalate, and polyethylene naphthalate.

[0083] As the anode, conductive metal oxide films or semi-transparent metal films with a high work function (preferably greater than 4.0 eV) are typically used. Examples of anode materials include metal oxides such as indium tin oxide (ITO), tin oxide, gold (Au), platinum (Pt), silver (Ag), and copper (Cu), or alloys containing at least one of these metals, as well as organic transparent conductive films such as polyaniline or its derivatives, and polythiophene or its derivatives. The anode can be formed from two or more layers, depending on the requirements. The anode film thickness can be appropriately selected considering conductivity (and light transmittance in the case of bottom-emitting types). The anode film thickness is preferably 10 nm to 10 μm, more preferably 20 nm to 1 μm, and most preferably 50 nm to 500 nm. Examples of anode fabrication methods include vacuum evaporation, sputtering, ion plating, and coating. In the case of top-emitting types, a reflective film can be provided below the anode to reflect light emitted to the substrate side.

[0084] An organic EL layer contains at least a light-emitting layer comprising organic matter. This light-emitting layer contains a luminescent material. Examples of luminescent materials include organic materials (low-molecular-weight or high-molecular-weight compounds) that emit fluorescence or phosphorescence. The light-emitting layer may also contain dopant materials. Examples of organic materials include pigment-based materials, metal complex-based materials, and polymeric materials. Dopant materials are added to the organic matter for purposes such as improving its luminescence efficiency or changing its emission wavelength. The thickness of the light-emitting layer, containing these organic materials and dopants as needed, is typically 2–200 nm.

[0085] (Pigment-based materials)

[0086] Examples of pigment-based materials include cyclopentylamine derivatives, tetraphenylbutadiene derivatives, triphenylamine derivatives, oxadiazole derivatives, pyrazolium quinoline derivatives, stilbene stilbene derivatives, stilbene arylene derivatives, pyrrole derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, triphenylamine derivatives, oxadiazole dimers, and pyrazolium dimers.

[0087] (Metal complex materials)

[0088] Examples of metal complex materials include indium complexes, platinum complexes, and other metal complexes exhibiting luminescence from triplet excited states; quinolinol aluminum complexes; benzoquinol beryllium complexes; benzoxazole zinc complexes; benzothiazole zinc complexes; azomethyl zinc complexes; porphyrin zinc complexes; europium complexes; and other metal complexes. Examples of metal complexes include those with a central metal of rare earth metals such as terbium (Tb), europium (Eu), or dysprosium (Dy), aluminum (Al), zinc (Zn), or beryllium (Be), and ligands with structures such as oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, or quinoline. Among these, metal complexes with a central metal of aluminum (Al) and ligands with quinoline structures are preferred. Among metal complexes with a central metal of aluminum (Al) and ligands with quinoline structures, tris(8-hydroxyquinoline)aluminum is preferred.

[0089] (Polymer Materials)

[0090] Examples of polymeric materials include poly(p-phenylenevinylene) derivatives, polythiophene derivatives, poly(p-phenylene) derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and substances formed by polymerizing the above-mentioned pigment or metal complex luminescent materials.

[0091] Among the aforementioned luminescent materials, examples of materials emitting blue light include stilbene aryl derivatives, oxadiazole derivatives, polyvinylcarbazole derivatives, poly(p-phenylene) derivatives, polyfluorene derivatives, and their polymers. Of these, polymeric materials are preferred. Among the polymeric materials, one or more from the group consisting of polyvinylcarbazole derivatives, poly(p-phenylene) derivatives, and polyfluorene derivatives are preferred.

[0092] Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, poly(p-phenylenevinyl)ethylene derivatives, polyfluorene derivatives, and their polymers. Among these, polymeric materials are preferred. Of the polymeric materials, one or more from the group consisting of poly(p-phenylenevinyl)ethylene derivatives and polyfluorene derivatives are preferred.

[0093] Examples of materials that can produce red color include coumarin derivatives, thiophene ring compounds, poly(p-phenylenevinyl)ethylene derivatives, polythiophene derivatives, polyfluorene derivatives, and their polymers. Among these, polymeric materials are preferred. Of the polymeric materials, one or more from the group consisting of poly(p-phenylenevinyl)ethylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferred.

[0094] (Doped materials)

[0095] Examples of dopant materials include perylene derivatives, coumarin derivatives, rubrogene derivatives, quinacridone derivatives, squaric acid cyanide derivatives, porphyrin derivatives, styrene-based pigments, tetraphenyl derivatives, pyrazolone derivatives, cyclodecanoylene, and phenoxazine.

[0096] In addition to the light-emitting layer, the organic EL layer can also be provided with layers between the light-emitting layer and the anode, and layers between the light-emitting layer and the cathode. Firstly, as a layer provided between the light-emitting layer and the anode, examples include: a hole injection layer for improving hole injection efficiency from the anode, and a hole transport layer for transporting holes injected from the anode or hole injection layer to the light-emitting layer. As a layer provided between the light-emitting layer and the cathode, examples include: an electron injection layer for improving electron injection efficiency from the cathode, and an electron transport layer for transporting electrons injected from the cathode or electron injection layer to the light-emitting layer.

[0097] (hole injection layer)

[0098] Materials that can be used to form the hole injection layer include phenylamines such as 4,4',4”-tri{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.

[0099] (hole transport layer)

[0100] Examples of materials constituting the hole transport layer include polyvinylcarbazole or its derivatives, polysilanes or their derivatives, polysiloxane derivatives with aromatic amines in the side or main chain, pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, benzidine derivatives, polyaniline or its derivatives, polythiophene or its derivatives, polyarylamine or its derivatives, polypyrrole or its derivatives, poly(p-phenylenevinylene) or its derivatives, and poly(2,5-thiophenevinylene) or its derivatives. Examples of benzidine derivatives include N,N'-diphenyl-N,N'-dinathylbenzidine.

[0101] When these hole injection layers or hole transport layers have the function of blocking electron transport, they are sometimes referred to as electron blocking layers.

[0102] (Electron transport layer)

[0103] Examples of materials constituting the electron transport layer include oxadiazole derivatives, anthraquinone dimethyl ether or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinone or derivatives thereof, tetraaminoanthraquinone dimethyl ether or derivatives thereof, fluorene derivatives, diphenyldiaminoethylene or derivatives thereof, biphenylquinone derivatives, 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof, etc. Metal complexes are also examples of derivatives. Among these, 8-hydroxyquinoline or derivatives thereof are preferred. Of 8-hydroxyquinoline or derivatives thereof, tris(8-hydroxyquinoline)aluminum is preferred from the perspective that it can also be used as an organic compound containing fluorescence or phosphorescence in the light-emitting layer.

[0104] (Electron injection layer)

[0105] As an electron injection layer, depending on the type of luminescent layer, examples include a single-layer electron injection layer comprising a calcium (Ca) layer; or an electron injection layer comprising a stacked structure of a layer formed of a Ca layer and a layer thereof, wherein the substance is one or more of the group consisting of metals belonging to Group IA and Group 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 belonging to Group IA of the periodic table or their oxides, halides, and carbonates with a work function of 1.5 to 3.0 eV include lithium (Li), lithium fluoride, sodium oxide, lithium oxide, and lithium carbonate. Examples of metals belonging to Group IIA of the periodic table or their oxides, halides, and carbonates with a work function of 1.5 to 3.0 eV include strontium (Sr), magnesium oxide, magnesium fluoride, strontium fluoride, barium fluoride, strontium oxide, and magnesium carbonate.

[0106] When these electron transport layers or electron injection layers have the function of blocking hole transport, they are sometimes referred to as hole blocking layers.

[0107] As a cathode, a transparent or translucent material with a relatively small work function (those with a work function of less than 4.0 eV are suitable) is preferred, as it facilitates electron injection into the emitting layer. Materials that can be used as cathodes 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), terbium (Tb), ytterbium (Yb), and other metals; or alloys containing two or more of the above metals; or alloys containing one or more of these 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), tin (Sn); or graphite or graphite interlayer compounds; or metal oxides such as ITO and tin oxides.

[0108] The cathode can be a stacked structure with two or more layers. Examples of stacked structures with two or more layers include the aforementioned metals, metal oxides, fluorides, their alloys, and stacked structures with metals such as Al, Ag, and Cr. The film thickness of the cathode can be appropriately selected considering conductivity and durability. The preferred film thickness of the cathode is 10 nm to 10 μm, more preferably 15 nm to 1 μm, and most preferably 20 nm to 500 nm. Examples of cathode fabrication methods include vacuum evaporation, sputtering, and lamination by hot pressing of metal thin films.

[0109] These layers disposed between the light-emitting layer and the anode, and between the light-emitting layer and the cathode, can be appropriately selected according to the performance requirements of the manufactured organic EL device. For example, the structure of the organic EL element used in this embodiment can have any of the layer configurations described below (i) to (xv).

[0110] (i) Anode / hole transport layer / light-emitting layer / cathode

[0111] (ii) Anode / Light-emitting layer / Electron transport layer / Cathode

[0112] (iii) Anode / Hole Transport Layer / Light Emitting Layer / Electron Transport Layer / Cathode

[0113] (iv) Anode / hole injection layer / light-emitting layer / cathode

[0114] (v) Anode / Light-emitting layer / Electron injection layer / Cathode

[0115] (vi) Anode / Hole Injection Layer / Light Emitting Layer / Electron Injection Layer / Cathode

[0116] (vii) Anode / Hole Injection Layer / Hole Transport Layer / Light Emitting Layer / Cathode

[0117] (viii) Anode / Hole Transport Layer / Light Emitting Layer / Electron Injection Layer / Cathode

[0118] (ix) Anode / Hole Injection Layer / Hole Transport Layer / Light Emitting Layer / Electron Injection Layer / Cathode

[0119] (x) Anode / Hole Injection Layer / Light Emitting Layer / Electron Transport Layer / Cathode

[0120] (xi) Anode / Light-emitting layer / Electron transport layer / Electron injection layer / Cathode

[0121] (xii) Anode / Hole Injection Layer / Light Emitting Layer / Electron Transport Layer / Electron Injection Layer / Cathode

[0122] (xiii) Anode / Hole Injection Layer / Hole Transport Layer / Light Emitting Layer / Electron Transport Layer / Cathode

[0123] (xiv) Anode / Hole Transport Layer / Light Emitting Layer / Electron Transport Layer / Electron Injection Layer / Cathode

[0124] (xv) Anode / Hole Injection Layer / Hole Transport Layer / Light Emitting Layer / Electron Transport Layer / Electron Injection Layer / Cathode

[0125] (Here, " / " indicates that the layers are adjacent and stacked. The same applies below.)

[0126] The sealing layer is designed to prevent water vapor, oxygen, and other gases from contacting the organic EL element, and to seal the organic EL element with a layer that has high barrier properties against these gases. This sealing layer is formed by alternating inorganic and organic films from bottom to top. The inorganic / organic laminate can be formed by repeating this process more than twice.

[0127] The inorganic membrane in an inorganic / organic laminate is designed to prevent organic electroluminescent (EL) elements from being exposed to gases such as water vapor and oxygen present in the environment where the organic EL device is placed. The inorganic membrane in an inorganic / organic laminate is preferably a continuous, dense membrane with few defects such as pinholes. Examples of inorganic membranes include individual films such as SiN films, SiO films, SiON films, Al2O3 films, and AlN films, as well as laminates thereof.

[0128] The organic film in the inorganic / organic laminate is provided to cover defects such as pinholes formed on the inorganic film and to impart surface flatness. The organic film is formed in a region narrower than the region where the inorganic film is to be formed. This is because if the organic film is formed in the same or a wider area as the inorganic film, the exposed areas of the organic film will deteriorate. However, the uppermost organic film formed in the uppermost layer of the entire sealing layer is formed in a region substantially the same as the inorganic film. Furthermore, it is formed in a manner that flattens the upper surface of the sealing layer. As the organic film, a composition with good adhesion to the aforementioned inorganic film is used.

[0129] The objective of this embodiment is to provide a sealant for organic electroluminescent display elements that forms the aforementioned organic film. This sealant is suitable for inkjet coating, for example, achieving excellent flatness with a film thickness of 3 μm or more in a short time. Based on the excellent inkjet ejection and flatness after inkjet coating, it not only exhibits excellent barrier properties against water vapor (hereinafter also referred to as low moisture permeability), but also avoids the situation where the sealant itself permeates through pinholes in the inorganic film, thus reducing the reliability of the organic EL element. When using an inkjet-based coating method, an organic film can be formed quickly and uniformly.

[0130] For the viscosity of the composition in this embodiment, it is preferable to have a viscosity of 2 mPa·s or more and 50 mPa·s or less, measured using an E-type viscometer at 25°C and 100 rpm. Since inkjet ejection is difficult, it is suitable to heat the inkjet head. When the viscosity is 2 mPa·s or more, the sealant for the coated organic EL display element does not flow out of the organic EL display element before curing, and does not flow into pinholes on the inorganic film, thus improving the reliability of the OLED element. When the viscosity is 50 mPa·s or less, inkjet coating becomes easier. More preferably, the viscosity of the composition is 5 mPa·s to 30 mPa·s.

[0131] The composition of this embodiment is a (meth)acrylic resin composition containing (A) an alkyldiol di(meth)acrylate with 4 or more but less than 20 carbon atoms and (B) a photopolymerization initiator. It should be noted that in this specification, when describing the carbon number of the main chain (alkyldiol, etc.), the carbon number of the (meth)acrylate portion is not included.

[0132] Examples of alkanes that are (A) alkane di(meth)acrylates of alkanediols having 4 or more but less than 20 carbon atoms include chain compounds and cyclic compounds. Chain compounds are preferred as alkanes. Chain compounds can be straight-chain or branched. Saturated hydrocarbons are preferred as alkanes.

[0133] Examples of alkanediol di(meth)acrylates (where the alkane is a chain compound and is a saturated hydrocarbon) having 4 or more but fewer than 20 carbon atoms (A) include 1,2-butanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,7-octanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,11-undecanediol di(meth)acrylate, 1, 12-Dodecanediol di(meth)acrylate, 1,13-Tetrazanediol di(meth)acrylate, 1,14-Tetradecanediol di(meth)acrylate, 1,15-Pentadecanediol di(meth)acrylate, 1,16-Hexadecanediol di(meth)acrylate, 1,17-Heptadecanediol di(meth)acrylate, 1,18-Octadecanediol di(meth)acrylate, 1,19-Nonadecanediol di(meth)acrylate, 1,20-Eicosenediol di(meth)acrylate, 3-Methyl-1,5-pentanediol di(meth)acrylate, 2,4-Diethyl-1,5-pentanediol di(meth)acrylate, neopentanediol di(meth)acrylate, etc. Examples of alkyldiol di(meth)acrylates (where the alkane is a cyclic compound) having 4 or more but less than 20 carbon atoms (A) include 1,2-cyclohexanediol di(meth)acrylate, 1,3-cyclohexanediol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, cyclohexanediethanol di(meth)acrylate, and hydrogenated bisphenol A di(meth)acrylate. Among alkyldiol di(meth)acrylates with 4 or more but less than 20 carbon atoms, a higher number of carbon atoms in the main chain is preferable from the perspective of OLED element reliability. However, this can lead to storage instability issues, such as crystallization and the formation of crystals during storage. From the viewpoints of OLED element reliability, moisture permeability, and storage stability, a carbon number of 6 or more but less than 18 is preferred, more preferably 9 or more but less than 16, even more preferably 12 or more but less than 16, and most preferably 12. In component (A), 1,12-dodecanediol di(meth)acrylate is preferred. Examples of component (A) include, for instance, "1.9ND-A" manufactured by Kyoei Chemical Co., Ltd. and "SR262" manufactured by Sartomer Co., Ltd.

[0134] (B) Photopolymerization initiators are used to promote the photocuring of resin compositions by sensitizing them with active light such as visible light or ultraviolet light. Photopolymerization initiators are preferably photoradical polymerization initiators. Examples of photoradical polymerization initiators include benzophenone and its derivatives, benzoin and its derivatives, anthraquinone and its derivatives, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzyl dimethyl ketal and other benzoin derivatives, diethoxyacetophenone, 4-tert-butyltrichloroacetophenone and other acetophenone derivatives, 2-dimethylaminoethyl benzoate, p-dimethylaminoethyl benzoate, and dibenzoin... Benzyl 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 ... [2.2.1] Camphorquinone derivatives such as heptane-1-carboxyl chloride, α-aminoalkyl phenyl ketone derivatives such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-1-butanone, benzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, benzoyl diethoxyphosphine oxide, 2,4,6-trimethylbenzoyl dimethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyl diethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and other acylphosphine oxide derivatives, phenyl-glyoxylic acid-methyl ester, oxy-phenyl-acetic acid 2-[2-oxy-2-phenyl-ethoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, etc. One or more photopolymerization initiators can be used in combination. Among these, acylphosphine oxide derivatives are preferred from the perspective of being able to cure using only visible light of 390 nm or higher during curing and being able to cure without damaging the organic electroluminescent display element. Among acylphosphine oxide derivatives, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is most preferred from the perspective of not reducing the transmittance of visible light when manufacturing the display and being able to cure using only light of 395 nm or higher. Examples of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide include "Irgacure TPO" manufactured by BASF JAPAN LTD.

[0135] Regarding the content of the photopolymerization initiator (B), relative to a total of 100 parts by mass of component (A) and component (C) used as needed, it is preferably 0.05 to 6 parts by mass, more preferably 0.5 to 4 parts by mass, most preferably 2 to 3.9 parts by mass, and even more preferably 2.2 to 3.5 parts by mass. When the content of component (C) is 0.05 parts by mass or more, a curing-promoting effect can be reliably obtained, and when it is 6 parts by mass or less, no reduction in visible light transmittance occurs when used in a display.

[0136] The amount of hydrophilic functional groups contained in the (meth)acrylate resin composition of this embodiment must be 4.80 to 7.60 mmol / g relative to the (meth)acrylate esters. The amount of hydrophilic functional groups in the (meth)acrylate resin composition is calculated using the following formula: the amount of hydrophilic functional groups relative to each (meth)acrylate ester for component (A) and, if present, component (C). Then, the product obtained by multiplying the amount of hydrophilic functional groups of each material by the mass fraction of each material as shown in the following formula in the (meth)acrylate resin composition is summed as the amount of hydrophilic functional groups in the (meth)acrylate resin composition. When calculating the mass fraction of the materials, the total amount of (meth)acrylate esters is taken as 100 parts by mass.

[0137]

[0138] (In the aforementioned formula, "materials" refers to each (meth)acrylate component.)

[0139]

[0140] (In the aforementioned formula, "materials" refers to each (meth)acrylate component.)

[0141] When the amount of the aforementioned hydrophilic functional group is 4.80 mmol / g or higher, there are more (meth)acryloyl groups as reactive groups, resulting in higher reactivity and satisfactory sealing performance of the organic EL element. This leads to low moisture permeability, thus improving the reliability and flatness of the organic EL element. When the amount is 7.60 mmol / g or lower, moisture is less likely to be released from the sealant inside the organic electroluminescent display element during reliability testing, and moisture does not reach the organic light-emitting material layer, making it less prone to black spots. From the viewpoint of reactivity and reliability, 4.80–7.60 mmol / g is preferred, and 5.00–7.10 mmol / g is more preferred.

[0142] In this embodiment, it is preferable to use (meth)acrylates other than component (A) as component (C). Component (C) can be one or more from the group consisting of monofunctional (meth)acrylates, difunctional (meth)acrylates, and polyfunctional (meth)acrylates. By using component (C), the amount of hydrophilic functional groups in the composition can be adjusted, and furthermore, viscosity, inkjet coating properties, and moisture permeability can also be adjusted.

[0143] Here, a hydrophilic functional group refers to a functional group whose maximum difference in electronegativity among the atoms constituting the functional group is 0.6 or more. Preferably, such a hydrophilic functional group is one or more selected from the group consisting of (meth)acryloyl, ester, aldehyde, nitro, hydroxyl, ethylene oxide, propylene oxide, ether, amide, cyclic amide, sulfoxide, carbonyl, carboxylic acid (salt), sulfonic acid (salt), sulfinic acid (salt), phosphonic acid (salt), phosphate (salt), sulfobetaine, carbobenzine, and phosphate betaine.

[0144] Examples of monofunctional (meth)acrylates as component (C) include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, isodecanyl methacrylate, lauryl methacrylate, stearyl methacrylate, etc., such as alkyl methacrylates, benzyl methacrylate, 4-butylphenyl methacrylate, phenyl methacrylate, 2,4,5-tetramethylphenyl methacrylate, 4-chlorophenyl methacrylate, etc. Phenoxymethyl methacrylate, phenoxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate (2-HPA), 2-(meth)acryloyloxyhexahydrophthalic acid, 2-(meth)acryloyloxyethyl-2-hydroxypropylphthalic acid, EO (ethylene oxide) modified phenol (meth)acrylate, EO modified cresol (meth)acrylate, EO modified nonylphenol (meth)acrylate, PO (propylene oxide) modified nonylphenol (meth)acrylate, ethoxylated o-phenylphenol (meth)acrylate, m-phenoxybenzyl (meth)acrylate Ester, 2-hydroxy-3-phenoxypropyl (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, phenol (ethylene oxide 2 moles modified) (meth)acrylate, phenol (ethylene oxide 4 moles modified) (meth)acrylate, p-cumylphenol ethylene oxide modified (meth)acrylate, nonylphenol ethylene oxide modified (meth)acrylate, nonylphenol (ethylene oxide 4 moles modified) (meth)acrylate, nonylphenol (ethylene oxide 8 moles modified) (meth)acrylate, nonylphenol (propylene oxide 2.5 moles modified) (meth)acrylate, ethylene oxide modified Monofunctional (meth)acrylates, such as phthalic acid (meth)acrylates and monohydroxyethyl (meth)acrylates, which have one or more aromatic hydrocarbon ring structures (hereinafter sometimes also called aromatic hydrocarbon groups) within their molecules, as well as cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, and methoxylated cyclodectrien (meth)acrylates, which have aliphatic hydrocarbon ring structures (hereinafter sometimes also called alicyclic hydrocarbon groups).Monofunctional (meth)acrylates, methoxylated cyclodecadiene (meth)acrylates, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, (meth)acrylate The following are examples of tert-butylaminoethyl acrylate, ethoxycarbonyl methyl methacrylate, 2-ethylhexyl carbitol methacrylate, ethylene oxide-modified succinic acid methacrylate, trifluoroethyl methacrylate, methacrylic acid, maleic acid, fumaric acid, ω-carboxy-polycaprolactone mono(meth)acrylate, methacrylic acid dimer, β-(meth)acryloyloxyethyl succinate hydrogen ester, N-(meth)acryloyloxyalkyl hexahydrophthalimide, 2-(1,2-cyclohexacarboxylimide)ethyl(meth)acrylate, etc. As a monofunctional (meth)acrylate component (C), methacrylates with cyclic structures such as cyclic amide groups, tetrahydrofurfuryl groups, piperidinyl groups, etc., containing heterocyclic structures, can be used.

[0145] Examples of difunctional (meth)acrylates as component (C) include dicyclopentyl dimethacrylate, 2-ethyl-2-butyl-propanediol (meth)acrylate, neopentyl glycol-modified trimethylolpropane dimethacrylate, stearic acid-modified pentaerythritol dimethacrylate, polypropylene glycol dimethacrylate, tricyclodecanediethanol dimethacrylate, 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, 2-(1,2-cyclohexanecarboxyimide)ethyl (meth)acrylate, and bisphenol A epoxy dimethacrylate. Examples of difunctional (meth)acrylates as component (C) include ethoxylated bisphenol A di(meth)acrylate compounds, propoxylated bisphenol A di(meth)acrylates, propoxylated ethoxylated bisphenol A di(meth)acrylates, etc., as shown in the following structural formulas.

[0146] In the following formulas, R is independently either a hydrogen atom or a methyl group. Regarding m and n in the formulas, m + n = 2 to 10 is preferred.

[0147]

[0148] Examples of polyfunctional (meth)acrylates as component (C) include trimethylolpropane tri(meth)acrylate, tri[(meth)acryloyloxyethyl]isocyanurate, dimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0149] The amount of hydrophilic functional groups in component (C) is preferably 3.00–15.00 mmol / g. A hydrophilic functional group amount of 3.00–15.00 mmol / g ensures sufficient reactivity and the reliability of the OLED device. From the viewpoint of reactivity and OLED device reliability, the amount of hydrophilic functional groups in component (C) is preferably 4.00–15.00 mmol / g, more preferably 4.10–8.20 mmol / g, and even more preferably 4.20–7.60 mmol / g.

[0150] From the perspectives of reactivity, OLED element reliability, and inkjet coating properties, component (C) is preferably one or more of the following: alkyl (meth)acrylates having 8 or more carbon atoms, (meth)acrylates having alicyclic hydrocarbon groups, and (meth)acrylates having aromatic hydrocarbon groups. As an alkyl (meth)acrylate having 8 or more carbon atoms, one or more of the following are preferably selected: isooctyl (meth)acrylate, isodecanyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate, with lauryl (meth)acrylate being the most preferred. As a (meth)acrylate having an alicyclic hydrocarbon group, one or more of the following are preferred: cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, and tricyclodecanediethanol di(meth)acrylate; more preferably, one or more of the following are preferred: dicyclopentyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentyloxyethyl (meth)acrylate. As a (meth)acrylate having an aromatic hydrocarbon group, ethoxylated o-phenylphenol (meth)acrylate is preferred.

[0151] Regarding the content of component (A), relative to the total of 100 parts by mass of components (A) and (C), 30 to 100 parts by mass are preferred, more preferably 30 parts by mass or more but less than 100 parts by mass. When the content of (A) is 30 parts by mass or more, the inkjet coating properties, low moisture permeability, and reliability of the organic EL element are excellent. From the perspective of inkjet coating properties, low moisture permeability, and reliability of the organic EL element, 55 to 99 parts by mass are preferred, more preferably 60 to 95 parts by mass, and even more preferably 65 to 95 parts by mass.

[0152] Regarding the content of component (C) in the presence of the present component, it is preferably more than 0 parts by mass and less than 70 parts by mass relative to the total of 100 parts by mass of components (A) and (C). When the content of component (C) is less than 70 parts by mass, the inkjet coating properties, low moisture permeability, and reliability of the organic EL element are excellent. From the perspective of inkjet coating properties, low moisture permeability, and reliability of the organic EL element, the content of component (C) is preferably 1 to 45 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 5 to 35 parts by mass.

[0153] As mentioned above, OLED elements are prone to degradation due to moisture, therefore, the composition of this embodiment preferably has a low water content. From the perspective of OLED element reliability, the water content is preferably 90 ppm or less, more preferably 50 ppm or less, and even more preferably 30 ppm or less.

[0154] Such moisture content can be measured using a commercially available moisture meter, typically a Karl Fischer moisture meter.

[0155] There are no particular limitations on the methods for reducing moisture content, but the following methods can be cited as examples.

[0156] (1) Remove moisture using a desiccant. After removing moisture, separate the desiccant by decantation or filtration. There are no particular limitations on the desiccant as long as it does not affect the resin composition; examples include polymeric adsorbents (molecular sieves, synthetic zeolites, alumina, silica gel, etc.), inorganic salts (calcium chloride, anhydrous magnesium sulfate, quicklime, anhydrous sodium sulfate, anhydrous calcium sulfate, etc.), and solid alkalis (sodium hydroxide, potassium hydroxide, etc.). (2) Remove moisture by heating under reduced pressure. (3) Purify by distillation under reduced pressure. (4) Remove moisture by blowing dry nitrogen, dry argon, or other inactive gases into each component. (5) Remove moisture by freeze-drying.

[0157] To reduce moisture content, the moisture content can be reduced for each component before mixing, or it can be reduced after the components are mixed. One or more moisture reduction processes can be used. After the moisture reduction process, to prevent re-introduction of moisture, it is preferable to perform the treatment under a non-reactive gas atmosphere.

[0158] Furthermore, as mentioned above, OLED elements are also prone to degradation due to oxygen; therefore, in the composition of this embodiment, a low dissolved oxygen content is preferable. From the perspective of OLED element reliability, a dissolved oxygen content of 20 ppm or less, more preferably 10 ppm or less, is preferred. On the other hand, dissolved oxygen reacts with active free radicals generated by the composition to generate inactive peroxy free radicals, thereby suppressing the thickening effect associated with polymerization of the composition. Therefore, from the perspective of storage stability, a content of 1 ppm or more, more preferably 2 ppm or more, is preferred.

[0159] Dissolved oxygen levels can be measured using methods such as reagent titration, diaphragm electrode method, or fluorescence method using fluorescent substances. There are no particular limitations on the measurement method, but the diaphragm electrode method is simple and preferred.

[0160] There are no particular limitations on the methods for reducing dissolved oxygen levels, but the following methods can be cited as examples.

[0161] (1) Remove oxygen by exposing the components to reduced pressure. (2) Remove oxygen by blowing dry nitrogen, dry argon, or other inert gases into each component. (3) Remove oxygen by exposing the components to low oxygen concentrations.

[0162] To reduce dissolved oxygen levels, oxygen levels can be reduced for each component before mixing, or after mixing. One or more steps can be used to reduce dissolved oxygen levels. After the dissolved oxygen reduction step, to prevent re-introduction of oxygen, it is preferable to perform the treatment under an inert gas atmosphere.

[0163] In the composition of this embodiment, from the perspective of inkjet ejection performance, (meth)acrylate monomers are preferred. Components (A) and (C) are preferably monomers. The molecular weight of the monomers is preferably 1000 or less. From the perspective of inkjet ejection performance, difunctional (meth)acrylate oligomers / polymers and polyfunctional (meth)acrylate oligomers / polymers are preferably contained in 3 parts by mass or less, more preferably 1 part by mass or less, and most preferably none, of 100 parts by mass of (meth)acrylate containing components (A) and (C). Oligomers / polymers refer to one or more from the group consisting of oligomers and polymers. The molecular weight of the oligomers / polymers is preferably greater than 1000.

[0164] To improve storage stability, the composition of this embodiment may use an antioxidant (D). Examples of antioxidants include methylhydroquinone, hydroquinone, octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate, 2,2-methylene-bis(4-methyl-6-tert-butylphenol), catechol, hydroquinone monomethyl ether, mono-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, p-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5-di-tert-butyl-p-benzoquinone, picric acid, citric acid, phenothiazine, tert-butylcatechol, 2-butyl-4-hydroxyanisole, and 2,6-di-tert-butyl-p-cresol. A combination of two or more antioxidants is preferred. Among these, phenolic antioxidants are preferred from the perspective of significant effects on transparency and storage stability. Among phenolic antioxidants, hindered phenolic antioxidants are preferred. As a hindered phenolic antioxidant, one or more of the following are preferred: octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate and 2,2-methylene-bis(4-methyl-6-tert-butylphenol); more preferably, octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate and 2,2-methylene-bis(4-methyl-6-tert-butylphenol). Examples of octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate include "Irganox 1076" manufactured by BASF JAPAN LTD. Examples of 2,2-methylene-bis(4-methyl-6-tert-butylphenol) include "SUMILIZER MDP-S" manufactured by Sumitomo Chemical Co., Ltd. In the case containing octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate and 2,2-methylene-bis(4-methyl-6-tert-butylphenol), the content ratio of octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate to 2,2-methylene-bis(4-methyl-6-tert-butylphenol) is preferably 10-90:90-10, more preferably 25-75:75-25, by mass ratio, for a total of 100 parts by mass of octadecyl 3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate and 2,2-methylene-bis(4-methyl-6-tert-butylphenol).

[0165] The antioxidant content is preferably 0.001 to 3 parts by mass, more preferably 0.01 to 2 parts by mass, relative to the total of 100 parts by mass of components (A) and (C). When it is 0.001 parts by mass or more, storage stability can be ensured, and when it is 3 parts by mass or less, good adhesion can be obtained without becoming uncured.

[0166] The composition of this embodiment can be used in the form of a resin composition. The composition of this embodiment can be used in the form of a light-curable resin composition. The composition of this embodiment can be used as a sealant for organic EL display elements.

[0167] Methods for curing the composition by irradiating it with visible light or ultraviolet light include methods such as curing the composition by irradiating it with at least one of visible light or ultraviolet light. Examples of energy sources for irradiating such visible light or ultraviolet light include deuterium lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, xenon lamps, xenon-mercury hybrid lamps, halogen lamps, excimer lamps, indium lamps, thallium lamps, LED lamps, and electrodeless discharge lamps. For the composition of this embodiment, from the perspective of minimizing damage to the organic EL element, curing at a wavelength of 380 nm or higher is preferred, curing at a wavelength of 395 nm or higher is more preferred, and curing at a wavelength of 395 nm is most preferred. Since emitting infrared light may cause the temperature of the irradiated part to rise, potentially damaging the organic EL element, a wavelength of 500 nm or lower is preferred as the energy source. An LED lamp with a single wavelength is preferred as the energy source.

[0168] When curing the composition by irradiation with visible light or ultraviolet light, it is preferable to irradiate the composition at a wavelength of 395 nm at a concentration of 100–8000 mJ / cm. 2 It is solidified by energy rays. The energy level is 100–8000 mJ / cm. 2 At this point, the composition will solidify, resulting in insufficient bond strength. (The value is 100 mJ / cm².) 2 At the above point, the composition is fully cured to 8000 mJ / cm². 2 The following conditions will not damage the organic EL element. The energy used to cure the composition is more preferably 300–2000 mJ / cm². 2 .

[0169] The transparency of the composition in this embodiment is as described below. When the thickness of the organic film is 1 μm or more and 10 μm or less, the spectral transmittance in the ultraviolet-visible light region of 360 nm or more and 800 nm or less is preferably 95% or more, more preferably 97% or more, and most preferably 99% or more. When it is 95% or more, an organic EL device with excellent brightness and contrast can be provided.

[0170] For the sealing layer formed by the composition of this embodiment, when the inorganic / organic laminate is set as 1 set, it is preferable to have 1 to 5 sets. This is because: when there are 6 or more inorganic / organic laminates, the sealing effect on the organic EL element is basically the same as when there are 5 sets. The thickness of the inorganic film of the inorganic / organic laminate is preferably 50 nm to 1 μm. The thickness of the organic film of the inorganic / organic laminate is preferably 1 to 15 μm, more preferably 3 to 10 μm. When the thickness of the organic film is 1 μm or more, it can completely cover the particles generated during element formation and be coated on the inorganic film while ensuring flatness. When the thickness of the organic film is 15 μm or less, moisture does not penetrate from the side of the organic film, and the reliability of the organic EL element is improved.

[0171] The sealing substrate is formed in a tightly sealed manner, covering the entire upper surface of the uppermost organic film of the sealing layer. Examples of such sealing substrates include the aforementioned substrates. Among these, a substrate that is transparent to visible light is preferred. Of the substrates transparent to visible light (transparent sealing substrates), one or more from the group consisting of glass substrates and plastic substrates are preferred, with glass substrates being more preferable.

[0172] The thickness of the transparent sealing substrate is preferably 1 μm or more and 1 mm or less, more preferably 10 μm or more and 800 μm or less, and most preferably 50 μm or more and 300 μm or less. By providing a transparent sealing substrate on top of the sealing layer, the degradation that occurs when the surface of the uppermost organic film comes into contact with the gas can be suppressed, thereby improving the barrier properties of the organic EL device.

[0173] Next, a method for manufacturing an organic EL device with such a configuration will be described. First, an anode, an organic EL layer containing a light-emitting layer, and a cathode patterned into a predetermined shape are sequentially formed on a first substrate using conventional methods, thereby forming an organic EL element. For example, when using an organic EL device as a dot matrix display device, in order to divide the light-emitting area into a matrix and form a bank, an organic EL layer containing a light-emitting layer is formed in the area surrounded by the bank.

[0174] Next, on the substrate where the organic EL element is formed, a first inorganic film of a predetermined thickness is formed by film formation methods such as PVD (Physical Vapor Deposition) such as sputtering, CVD (Chemical Vapor Deposition) such as plasma CVD, etc. Subsequently, the composition of this embodiment is adhered to the first inorganic film using film formation methods such as solution coating, spraying, flash evaporation, inkjet printing, etc. Among these, inkjet printing is preferred from a productivity perspective. Then, the composition is cured by irradiation with energy rays such as ultraviolet light, electron beam, or plasma to form a first organic film. Through the above steps, an inorganic / organic laminate is formed. The curing rate of the composition is not particularly limited as long as the effect of this embodiment is achieved; for example, it is preferably 90% or more, more preferably 95% or more, based on the value obtained according to the measurement method described later.

[0175] The process of forming the inorganic / organic laminate shown above is repeated a specified number of times. Among them, the final group, that is, the uppermost inorganic / organic laminate, can be attached to the upper surface of the inorganic film by means of coating, flash evaporation, inkjet printing, etc., to planarize the upper surface of the composition.

[0176] Next, a transparent sealing substrate is bonded to the surface of a substrate to which the composition is attached. During bonding, alignment is performed. Then, energy rays are irradiated from the transparent sealing substrate side, causing the composition of this embodiment, existing between the uppermost inorganic film and the transparent sealing substrate, to solidify. As a result, the composition solidifies, forming an uppermost organic film, and the uppermost organic film is bonded to the transparent sealing substrate. This concludes the method for manufacturing an organic EL device.

[0177] After the composition is attached to the inorganic film, it can be polymerized by locally irradiating it with energy rays. This process prevents the collapse of the shape of the composition forming the uppermost organic film when a transparent sealing substrate is placed on it. The thicknesses of the inorganic and organic films can be the same or different in each inorganic / organic laminate.

[0178] The above description uses a top-emitting organic EL device as an example. This embodiment can also be applied to a bottom-emitting organic EL device that emits light generated in the organic EL layer from the substrate side.

[0179] The organic EL element in this embodiment can be used as a surface light source, a segment display device, or a dot matrix display device.

[0180] According to this embodiment, a sealing layer is formed to isolate the organic EL element formed on the first substrate from external gases, and a transparent sealing substrate is disposed on the sealing layer. Therefore, a sealing structure with sufficient barrier properties against water vapor and oxygen for the organic EL element can be obtained. According to this embodiment, a sealing structure with sufficient adhesive strength between the transparent sealing substrate and the sealing layer can be obtained.

[0181] According to this embodiment, after the composition of this embodiment, constituting the uppermost organic film of the sealing layer, is attached, a transparent sealing substrate is placed on without curing the composition, and then the composition is cured. Therefore, the bonding between the sealing layer and the transparent sealing substrate can be performed simultaneously with the formation of the uppermost organic film constituting the sealing layer. As a result, this embodiment has the following effect: the process is simplified compared to bonding the sealing layer and the transparent sealing substrate with an adhesive.

[0182] For the composition of this embodiment, preferably according to JIS Z 0208:1976, the moisture permeability of the cured body after being exposed to 85°C and 85%RH for 24 hours and measured at a thickness of 100μm is 350g / m. 2 The following is a moisture permeability rating: 350 g / m² 2 When moisture does not reach the organic light-emitting material layer, black spots are less likely to form.

[0183] According to this embodiment, a sealant for organic EL display elements that can be easily coated using inkjet printing, exhibiting excellent reliability of the OLED element, transparency of the cured body, and barrier properties can be provided. According to this embodiment, a method for manufacturing an organic EL display element using the sealant for organic EL display elements can be provided. Inkjet printing refers to a method of coating an object non-contactly by ejecting fine droplets from a nozzle.

[0184] Example

[0185] (Experimental Examples 1-17)

[0186] The composition was prepared and evaluated using the following methods.

[0187] (Preparation of the composition)

[0188] The materials used were those listed in Table 1. The materials were mixed according to the compositions in Table 2, dehydrated using a molecular sieve (UNIONSHOWA KK 5A granules), and then exposed in a glove box with an oxygen concentration below 5 ppm for at least 72 hours to prepare the composition. Using the obtained composition, the following evaluation methods were used to determine the E-type viscosity, water content, dissolved oxygen content, moisture permeability, coating area expansion, curing rate, transparency, and organic EL evaluation. The results are shown in Table 2. The composition names in Table 2 use the abbreviations shown in Table 1.

[0189] [Table 1]

[0190] 1.9ND-A 1,9-Nonadiol diacrylate Kyoeisha Chemical SR262 1,12-Dodecanediol dimethacrylate Sartomer 1.14-TDD 1,14-Tetradecanediol dimethacrylate Denka Co., Ltd. Synthesis 1.16-HDD 1,16-Hexadecanediol dimethacrylate Denka Co., Ltd. Synthesis A-LEN-10 Ethoxylated o-phenylphenol acrylate Shin-Nakamura Chemical FA-512AS Dicyclopentyloxyethyl acrylate Hitachi Chemical Co., Ltd. FA-513AS dicyclopentyl acrylate Hitachi Chemical Co., Ltd. FA-513M Dicyclopentyl methacrylate Hitachi Chemical Co., Ltd. PoB-A m-Phenoxybenzyl acrylate Kyoeisha Chemical DCP Tricyclodecanediethanol dimethacrylate Shin-Nakamura Chemical BPE-200 Ethoxylated bisphenol A dimethacrylate (m+n=4) Shin-Nakamura Chemical 9G Polyethylene glycol dimethacrylate (n=9) Shin-Nakamura Chemical SR205NS Triethylene glycol dimethacrylate Sartomer oDM Octadecyl methacrylate PEG200D Polyethylene glycol dimethacrylate PETA Pentaerythritol tetraacrylate LA Lauryl acrylate Kyoeisha Chemical TMPTA Trimethylolpropane triacrylate East Asia Synthesis MDP-S 2,2-Methylenebis(6-tert-butyl-4-methylphenol) Sumitomo Chemical Irg-1076 3-[3,5-di-tert-butyl-4-hydroxyphenyl]octadecyl propionate BASF JAPAN LTD. TPo 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide BASF JAPAN LTD.

[0191] [Table 2]

[0192]

[0193] [E-type viscosity]

[0194] The viscosity of the composition was determined using an E-type viscometer (cone plate type: cone angle 1°34', radius of conical rotor 24mm) at a temperature of 25°C and a rotation speed of 100 rpm.

[0195] [Moisture content]

[0196] The water content of the composition was determined using AQUAMICRON AX (manufactured by Mitsubishi Chemical Corporation) as a Karl Fischer solution and measured by a micro moisture analyzer CA-06 (manufactured by Mitsubishi Chemical Corporation).

[0197] Dissolved oxygen content

[0198] The dissolved oxygen content of the composition was measured using a dissolved oxygen meter (manufactured by Iijima Electronics Co., Ltd., trade name "DOmeter B-506 (diaphragm type primary cell)").

[0199] [Light curing conditions]

[0200] In evaluating the cured properties of the composition, the composition was cured under the following light irradiation conditions. Using an LED lamp emitting a wavelength of 395 nm (HOYA UV-LED LIGHT SOURCE H-4MLH200-V1), the cumulative light intensity at a wavelength of 395 nm was 1,500 mJ / cm². 2 The composition is photocured under certain conditions to obtain a cured body.

[0201] [Humidity permeability]

[0202] A sheet-like cured body with a thickness of 0.1 mm was prepared under the aforementioned light curing conditions. According to JIS Z0208:1976 "Test method for moisture permeability of moisture-proof packaging materials (cup method)", calcium chloride (anhydrous) was used as a desiccant, and the test was conducted at an ambient temperature of 85°C and a relative humidity of 85%.

[0203] The cured composition and the uncured composition were compared using an infrared spectrometer (Thermo Scientific, Nicolet IS5, DTGS detector, 4cm resolution). -1 The infrared spectra of the sample were measured by incident infrared light. Using the obtained infrared spectra, peaks at 2950 cm⁻¹ that did not change before and after curing were identified. -1 The stretching vibration peak of the carbon-hydrogen bond of the methylene group observed nearby was used as an internal standard. Based on the peak area of ​​this internal standard before and after curing, and the 810 cm peak of the out-of-plane bending vibration of the carbon-hydrogen bond attributable to the carbon-carbon double bond of (meth)acrylate, the curing was determined. -1 The curing rate is calculated using the following formula, which measures the area of ​​the nearby peaks before and after curing.

[0204] Curing rate (%) = [1 - (Ax / Bx) / (Ao / Bo)] × 100

[0205] Here,

[0206] Ao: indicates 810cm -1 The peak area near the solidification site.

[0207] Ax: represents 810cm -1 The area of ​​the solidified peak nearby.

[0208] Bo: indicates 2950cm -1 The peak area near the solidification site.

[0209] Bx: Indicates 2950cm -1 The area of ​​the solidified peak nearby.

[0210] [Transparency]

[0211] The compositions obtained in each experimental example were formed to a thickness of 10 μm between two 25 mm × 25 mm × 1 mm thick glass plates (alkali-free glass, Corning Eagle XG). An LED lamp was used to irradiate the plates at a dose of 1500 mJ / cm². 2 The material was irradiated with ultraviolet light with a wavelength of 395 nm to cure it, thereby obtaining a cured body. The transmittance of the cured body at 380 nm, 412 nm, and 800 nm was measured using a UV-Vis spectrophotometer (Shimadzu Corporation "UV-2550") to determine its transparency.

[0212] [Expansion rate of coating area]

[0213] Using an inkjet ejector (MUSASHI ENGINEERING Corporation MID500B, solvent-based "MIDhead"), the compositions obtained in each experimental example were patterned onto a 70mm × 70mm × 0.7mm substrate (alkali-free glass (Corning Eagle XG)) in a manner of 4mm × 4mm × 10μm. The alkali-free glass was cleaned with acetone and isopropanol before use, followed by cleaning with a TECHNOVISION Corporation UV-208 UV ozone cleaning system for 5 minutes. Immediately after patterning, the substrate was left to stand for 5 minutes at an ambient temperature of 23°C and a relative humidity of 50%. The flatness after inkjet coating was evaluated by the expansion rate of the coated area (refer to the formula below). A smaller expansion rate of the coated area indicates better shape retention and superior positional control, which is considered preferable.

[0214] (Expansion rate of coating area) = ((Contact area of ​​the composition in contact with the substrate surface 5 minutes after patterning) / (Contact area of ​​the composition in contact with the substrate surface immediately after patterning)) × 100 (%)

[0215] [Organic EL Evaluation]

[0216] Fabrication of organic EL (Elastic Optical Component) substrates

[0217] A 30 mm square glass substrate with an ITO electrode (700 μm thick) was cleaned with acetone and isopropanol, respectively. Subsequently, the following compounds were sequentially deposited using vacuum evaporation to form thin films, resulting in a 2 mm square organic EL element consisting of an anode / hole injection layer / hole transport layer / light-emitting layer / electron injection layer / cathode. The structures of each layer are as follows.

[0218] • Anode: ITO; Anode film thickness: 150 nm

[0219] • Hole injection layer 4,4',4”-tris{2-naphthyl(phenyl)amino}triphenylamine (2-TNATA)

[0220] Hole transport layer N,N'-diphenyl-N,N'-dinaphthylbenzidine (α-NPD)

[0221] • Light-emitting layer tris(8-hydroxyquinoline)aluminum (metal complex material), film thickness of the light-emitting layer The light-emitting layer also functions as an electron transport layer.

[0222] • Electron-injected layer lithium fluoride

[0223] • Cathode aluminum film thickness 150nm

[0224] [Fabrication of Organic EL Components]

[0225] Subsequently, a mask (covering material) with a 10mm × 10mm opening was set to cover a 2mm × 2mm organic EL element, and a SiN film was formed by plasma CVD. Next, under a nitrogen atmosphere, using the aforementioned inkjet apparatus, the composition (organic film) obtained in each experimental example was coated with a thickness of 10μm to cover a 2mm × 2mm organic EL element. After the composition was cured under the aforementioned photocuring conditions, a mask (covering material) with a 10mm × 10mm opening was set to cover the entire cured body, and a SiN film was formed by plasma CVD, thereby obtaining an organic EL display element.

[0226] The formed SiN (inorganic film) is approximately 1 μm thick. Subsequently, a 30 mm × 30 mm × 25 μm transparent substrate-free double-sided adhesive tape is bonded to a 30 mm × 30 mm × 0.7 mm alkali-free glass (Eagle XG manufactured by Corning) to fabricate an organic EL element (organic EL evaluation).

[0227] [Initial stage]

[0228] Apply a 6V voltage to the freshly fabricated organic EL element for 10 seconds, observe the luminescence state of the organic EL element visually and under a microscope, and measure the diameter of the black spot.

[0229] [Durability]

[0230] After exposing the freshly fabricated organic EL element to 85°C and 85% relative humidity for 500 hours, a voltage of 6V was applied, and the luminescence state of the organic EL element was observed visually and under a microscope. The diameter of the black spot was then measured.

[0231] The diameter of the black spots can be used as an indicator to evaluate the degree of penetration of the sealant into the pinholes of the passivation film and the extent to which moisture in the sealant is expelled as venting gas. The diameter of the black spots is preferably less than 300 μm, more preferably less than 50 μm, and the absence of black spots is considered optimal.

[0232] Based on the above experimental examples, the following judgments can be made.

[0233] The composition of this embodiment provides a reliable organic EL element, excellent ejection performance based on high-precision inkjet printing, excellent shape retention after inkjet coating, and excellent low moisture permeability.

[0234] When the following conditions are met: (A) alkanediol di(meth)acrylate containing 4 or more but less than 20 carbon atoms, (B) a photopolymerization initiator is present, and the amount of hydrophilic functional groups relative to (meth)acrylate is in the range of 4.80–7.60 mmol / g, the product exhibits excellent reliability, inkjet ejection performance, coating flatness, and low moisture permeability. Furthermore, the diameter of the initial black spots is also small (Experimental Examples 1–12).

[0235] On the other hand, if the amount of hydrophilic functional groups is not in the range of 4.80 to 7.60 mmol / g, not only is the diameter of the black spots generated in the early stage large, but the moisture permeability is also high and the reliability is problematic (Experimental Examples 13 to 17).

[0236] In addition, without using alkyldiol di(meth)acrylates with 4 or more carbon atoms and less than 20 carbon atoms, not only is there a small expansion rate of the coating area, problems with inkjet ejection and flatness after coating, but also high moisture permeability and reliability issues (Experimental Example 15).

[0237] Industrial availability

[0238] The composition of this embodiment exhibits excellent inkjet ejection precision and flatness after inkjet coating, along with low moisture permeability and transparency, preventing degradation of organic EL components. This embodiment enables inkjet coating in a short time. The composition of this embodiment is suitable for bonding components used in electronic products, particularly display components such as organic ELs, image sensors such as CCDs and CMOS sensors, and even semiconductor components. It is especially suitable for bonding organic EL seals, meeting the requirements for adhesives used in the packaging of organic EL components.

[0239] The above composition is one embodiment of this invention. The organic EL element sealant, curing body, cover, bonding body, organic EL device, display, and manufacturing method thereof using the composition of this invention also have the same structure and effect.

Claims

1. A sealant for an organic electroluminescent display element, comprising: (A) an alkyl diol di(meth)acrylate with 4 or more and 20 or fewer carbon atoms, (B) a photopolymerization initiator and (C) a (meth)acrylate other than component (A), wherein the amount of hydrophilic functional groups relative to the (meth)acrylate is in the range of 5.00 to 7.60 mmol / g; Moisture content below 90 ppm; (C) The amount of hydrophilic functional groups relative to (meth)acrylate in component C is 4.20~7.60 mmol / g. (C) The ingredient contains one or more of the following groups: lauryl acrylate, dicyclopentyl acrylate, dicyclopentyloxyethyl acrylate, dicyclopentenyl acrylate, and dicyclopentenyloxyethyl acrylate.

2. The sealant for organic electroluminescent display elements according to claim 1, wherein, The product contains 30 or more but less than 100 parts by mass of component (A), 0.05 to 6 parts by mass of component (B), and more than 0 parts by mass but less than 70 parts by mass of component (C) relative to a total of 100 parts by mass of components (A) and (C).

3. The sealant for organic electroluminescent display elements according to claim 2, wherein, The product contains 55 to 99 parts by mass of component (A) and 1 to 45 parts by mass of component (C) relative to a total of 100 parts by mass of components (A) and (C).

4. The sealant for organic electroluminescent display elements according to any one of claims 1 to 3, wherein the viscosity measured by an E-type viscometer at 25°C is 2 mPa·s or more and 50 mPa·s or less.

5. The sealant for organic electroluminescent display elements according to any one of claims 1 to 3, wherein, The water content is below 50 ppm.

6. The sealant for organic electroluminescent display elements according to any one of claims 1 to 3, wherein, Dissolved oxygen levels are between 1 ppm and 20 ppm.

7. The sealant for organic electroluminescent display elements according to any one of claims 1 to 3, wherein, It does not contain difunctional (meth)acrylate oligomers / polymers or polyfunctional (meth)acrylate oligomers / polymers.

8. The sealant for organic electroluminescent display elements according to any one of claims 1 to 3, wherein, (A) The component is alkyl diol di(meth)acrylate with 12 or more carbon atoms and less than 16 carbon atoms.

9. The sealant for organic electroluminescent display elements according to any one of claims 1 to 3, wherein, (A) The component is 1,12-dodecanediol di(meth)acrylate.

10. The sealant for organic electroluminescent display elements according to claim 2 or 3, wherein, (C) contains lauryl methacrylate.

11. The sealant for organic electroluminescent display elements according to any one of claims 1 to 3, wherein, (B) The component is an acylphosphine oxide derivative.

12. A cured body obtained by curing an organic electroluminescent display element according to any one of claims 1 to 11 with a sealant.

13. A bonding body obtained by bonding an organic electroluminescent display element according to any one of claims 1 to 11 with a sealant.

14. A method for curing the sealant for an organic electroluminescent display element according to any one of claims 1 to 11, characterized in that, Curing is performed using wavelengths above 380nm and below 500nm.

15. A method for curing the sealant for an organic electroluminescent display element according to any one of claims 1 to 11, characterized in that, Curing was performed using LEDs with an emission wavelength of 395nm.

16. A method for applying a sealant to an organic electroluminescent display element according to any one of claims 1 to 11, wherein, The coating is applied using an inkjet printing method.

17. An organic EL device comprising a sealant for an organic electroluminescent display element according to any one of claims 1 to 11.

18. A display comprising a sealant for an organic electroluminescent display element according to any one of claims 1 to 11.

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