Sealing agent, sealing material for organic electroluminescent element, organic electroluminescent display device, and method for producing sealing agent for organic electroluminescent element

Abstract

Provided is a sealing agent for organic electroluminescent elements, which comprises a radical-polymerizable compound, a photopolymerization initiator, and a persistent radical-type compound having a persistent radical and which has an acid value of 0.01-0.15 (mgKOH / g).

Description

Technical Field

[0001] The present invention relates to a sealing agent for an organic electroluminescence element, a sealing material, an organic electroluminescence display device, and a method for producing a sealing agent for an organic electroluminescence element.

Background Art

[0002] An organic electroluminescence element (hereinafter also referred to as an organic EL element) has attracted attention as an element body capable of emitting light with high luminance. However, the organic EL element has a problem that it deteriorates due to oxygen and moisture, and the light emission characteristics deteriorate. To solve this problem, techniques for sealing the organic EL element to prevent deterioration have been studied.

[0003] As one of the sealing methods, for example, Patent Document 1 describes a sealing agent for an organic EL element that contains a polymerizable compound and a polymerization initiator, has a viscosity at 25°C of 5 to 50 mPa·s, a surface tension at 25°C of 15 to 35 mN / m, and a water content at 25°C after standing for 24 hours in an environment of 25°C and 50% RH of 1000 ppm or less.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a sealing agent for an organic EL element, a thermosetting sealing agent and a photocurable sealing agent are known. The photocurable sealing agent does not require heating during sealing, so that a sealing material can be formed without exposing the organic EL element to high heat, and has an advantage that deformation and deterioration of the organic EL element due to high heat are suppressed.

[0006] In recent years, the required characteristics of electronic devices have been increasing. For example, there is a demand for a sealing material that can achieve higher reliability for organic EL elements.

[0007] However, with conventional photocurable sealants, it has been difficult to sufficiently suppress the generation of dark spots in endurance tests under high temperature and high humidity.

[0008] Therefore, an object of the present invention is to provide a sealing agent for organic EL elements that can significantly suppress the generation of dark spots under high temperature and high humidity. Another object of the present invention is to provide a sealing material formed from the sealing agent for organic EL elements, an organic EL display device including the sealing material, and a method for manufacturing the sealing agent for organic EL elements.

Means for Solving the Problems

[0009] The present invention relates to, for example, the following <1> to <7>. <1> A sealing agent for an organic electroluminescence element, which contains a radically polymerizable compound, a photopolymerization initiator, and a stable radical type compound having a stable radical, and has an acid value of 0.01 to 0.15 (mgKOH / g). <2> The sealing agent according to <1>, wherein the stable radical is a nitroxide radical. <3> A sealing material including a cured product of the sealing agent according to <1> or <2>. <4> An organic electroluminescence display device including an organic electroluminescence element and the sealing material according to <3> for sealing the organic electroluminescence element. <5> A method for manufacturing the sealing agent according to <1> or <2>, a pretreatment step of degassing at least a part of the radically polymerizable compound in an environment of 10 to 100°C and 1000 Pa or less so that the acid value of the sealing agent becomes 0.01 to 0.15 (mgKOH / g), a mixing step of mixing the radically polymerizable compound, the photopolymerization initiator, and the stable radical type compound having a stable radical to obtain the sealing agent. A method for manufacturing a sealing agent for an organic electroluminescence device, which includes

Advantages of the Invention

[0010] According to the present invention, there is provided a sealing agent for an organic EL device that can significantly suppress the generation of dark spots under high temperature and high humidity. Further, according to the present invention, there are provided a sealing material formed from the sealing agent for an organic EL device, an organic EL display device including the sealing material, and a method for manufacturing the sealing agent for an organic EL device.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0012] In this specification, the notation "X to Y" in the description of a numerical range means X or more and Y or less, unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% or more and 5 mass% or less".

[0013] In the notation of a group (atomic group) in this specification, a notation that does not indicate whether it is substituted or unsubstituted includes both those having no substituent and those having a substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

[0014] In this specification, the notation "(meth)acrylic" includes both acrylic and methacrylic. The same applies to similar notations such as "(meth)acrylate".

[0015] <Sealing Agent> The sealing agent of this embodiment contains a radically polymerizable compound, a photopolymerization initiator, and a stable radical type compound having a stable radical. Further, the sealing agent of this embodiment has an acid value of 0.01 to 0.15 (mgKOH / g).

[0016] The encapsulant of this embodiment is for encapsulating an organic electroluminescence element. That is, the encapsulant of this embodiment is used to encapsulate an organic EL element to manufacture an organic EL display device. Since the encapsulant of this embodiment contains a photoinitiator, it is a photocurable encapsulant.

[0017] By encapsulating the organic EL element with the encapsulant of this embodiment, the generation of dark spots under high temperature and high humidity is significantly suppressed.

[0018] The reason why the above effect is achieved by the encapsulant of this embodiment is not necessarily limited, but the following reasons are considered. According to the findings of the present inventors, in the conventional encapsulant, a trace amount of acid component exists in the encapsulating material formed by the curing of the encapsulant. When moisture enters the encapsulating material due to the presence of the acid component, deterioration due to hydrolysis of the encapsulating material may occur, resulting in a decrease in reliability. Since the acid value of the encapsulant of this embodiment is 0.15 mgKOH / g or less, the residual acid component in the encapsulating material is small, and even when a trace amount of moisture enters the encapsulating material, hydrolysis of the encapsulating material is unlikely to occur. Therefore, according to the encapsulant of this embodiment, an encapsulating material that is difficult to deteriorate even under high temperature and high humidity can be formed, and the generation of dark spots caused by the deterioration of the encapsulating material can be suppressed.

[0019] In addition, the acid value of the encapsulant of this embodiment is 0.01 mgKOH / g or more, and it contains an extremely small amount of acid component. In this embodiment, this extremely small amount of acid component acts as a polymerization inhibitor, making the encapsulant excellent in storage stability, and it is considered that a decrease in reliability due to the deterioration of the encapsulant during storage is suppressed.

[0020] In addition, the encapsulant of this embodiment has excellent dischargeability from the coating device. Specifically, according to the encapsulant of this embodiment, when discharging from the coating device, bending of the discharged liquid, variation in the amount of the discharged liquid, etc. are suppressed, and good dischargeability is maintained. Thereby, according to the encapsulant of this embodiment, a coating film with significantly less thickness unevenness and excellent flatness can be formed. Also, according to the encapsulant of this embodiment, an encapsulating material that contributes to improving the reliability of the organic EL element can be formed.

[0021] Although the reason why the above effects are achieved by the encapsulant of the present embodiment is not necessarily limited, the following reasons can be considered. According to the findings of the present inventors, in conventional photocurable encapsulants, when the encapsulant is discharged from the coating device, the bending of the discharged liquid, the variation in the amount of the discharged liquid, etc. occur, resulting in uneven thickness in the coating film and a decrease in the flatness of the coating film in some cases. As a cause of this, photocurable encapsulants are likely to undergo unintended polymerization before use (for example, during storage, transportation, etc.), and it is considered that fine particles generated by the polymerization narrow the flow path of the coating device, causing bending of the discharged liquid, variation in the amount of the discharged liquid, etc. In the encapsulant of the present embodiment, by containing a stable radical type compound, although it is a photocurable encapsulant, unintended polymerization before use (for example, during storage, transportation, etc.) and the generation of particles due to the polymerization are significantly suppressed. Therefore, in the encapsulant of the present embodiment, coating defects caused by particles are suppressed, excellent dischargeability from the coating device, and high flatness of the coating film after coating are realized.

[0022] In addition, in conventional photocurable encapsulants, at the time of light irradiation, reaction points such as a photoinitiator, radical species generated from the photoinitiator, and radical species generated during the polymerization process may remain in the cured body due to uneven thickness of the coating film, variation in the irradiation amount, etc. And due to the remaining of such reaction points, further polymerization may occur in the cured body after the encapsulation operation, and the cured body may shrink due to curing. Usually, an inorganic protective film with a thickness of about 1 μm is provided between the organic EL element and the encapsulating material (cured body of the encapsulant), but when curing shrinkage occurs, a load is applied to the inorganic protective film and cracks are likely to occur, and the reliability of the organic EL element may decrease due to the intrusion of water or oxygen from the cracks. The encapsulant of the present embodiment contains a stable radical type compound, so that the above-mentioned reaction points are less likely to remain in the cured body, and further polymerization from the reaction points is also suppressed. Therefore, according to the encapsulant of the present embodiment, alteration due to reaction points is less likely to occur, damage to the inorganic protective film due to curing shrinkage can be suppressed, and an encapsulating material that contributes to improving the reliability of the organic EL element can be formed.

[0023] (Radical polymerizable compound) The radical polymerizable compound may be any compound that can be polymerized by active species generated from a photoinitiator described later. The radical polymerizable compound may be used alone or in combination of two or more kinds.

[0024] The radical polymerizable compound can be said to be a compound having a radical polymerizable group. Examples of the radical polymerizable group include a vinyl group, a (meth)acryloyl group, an allyl group, a vinyl ether group, a vinyl ester group, a (meth)acrylamide group, etc. Among these, the (meth)acryloyl group is particularly preferable.

[0025] The radical polymerizable compound preferably contains, for example, a polyfunctional compound having two or more radical polymerizable groups. The number of radical polymerizable groups in the polyfunctional compound may be, for example, 2 to 6, preferably 2 to 4. By using the polyfunctional compound, the photocurability tends to be further improved.

[0026] From the viewpoint of obtaining well-balanced various properties as a sealing material, as the polyfunctional compound, a bifunctional compound having two radical polymerizable groups is preferable.

[0027] The radical polymerizable compound may contain a monofunctional compound having one radical polymerizable group. From the viewpoint of facilitating the adjustment of the polymerization rate, physical properties of the cured product, etc., the radical polymerizable compound preferably contains a polyfunctional compound and a monofunctional compound.

[0028] When the radical polymerizable compound contains a polyfunctional compound and a monofunctional compound, the proportion of the polyfunctional compound in the radical polymerizable compound may be, for example, 30% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, and may be 85% by mass or more or 90% by mass or more. Also, the proportion of the polyfunctional compound in the polymerizable compound may be, for example, 100% by mass or less, preferably 95% by mass or less. That is, the proportion of the polyfunctional compound in the radically polymerizable compound may be, for example, 30 to 100% by mass, 30 to 95% by mass, 50 to 100% by mass, 50 to 95% by mass, 60 to 100% by mass, 60 to 95% by mass, 70 to 100% by mass, 70 to 95% by mass, 80 to 100% by mass, 80 to 95% by mass, 85 to 100% by mass, 85 to 95% by mass, 90 to 100% by mass, or 90 to 95% by mass.

[0029] As the polyfunctional compound, a polyfunctional (meth)acrylic compound having two or more (meth)acryloyl groups is preferable. Specific examples of the polyfunctional (meth)acrylic compound include Bis(1-(meth)acryloxy-2-hydroxypropyl) phthalate, bis(2-(meth)acryloxyethyl) phosphate, bis((meth)acryloxy-2-hydroxypropyloxy)diethylene glycol, bisphenol A di(meth)acrylate, bisphenol A di-(3-(meth)acryloxyethyl) ether, bisphenol A di-(3-(meth)acryloxy-2-hydroxypropyl) ether, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di-(3-(meth)acryloxy-2-hydroxypropyl) ether, 1,4-butanediol di(meth)acrylate, 1,3-butanediol bis((meth)acryloxypropionate), 1,4-butanediol bis((meth)acryloxypropionate), 2-butene-1,4-diol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, 2,2-dimethyl-1,3-propanediol di(meth)acrylate, dipentaerythritol ether di(meth)acrylate, diphenolic acid di-(3-(meth)acryloxy-2-hydroxypropyl) ether, dipropylene glycol di(meth)acrylate, 7,7,9-trimethyl-3,13-dioxo-3,14-dioxa-5,12-diazapentadecane-1,16-diol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,2-ethanediol di(meth)acrylate, 1,2-ethanediol bis((meth)acryloxypropionate), 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,4-phenylene di(meth)acrylate, 1-phenyl-1,2-ethanediol di(meth)acrylate, polyoxyethyl-2,2-di(p-hydroxyphenyl)propane di(meth)acrylate, 1,2-propanediol di(meth)acrylate, 1,3-propanediol 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, tetraethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-1,10-decane diacrylate and other bifunctional (meth)acrylic compounds; 1,2,4-butanetriol tri(meth)acrylate, glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, polyoxypropyl trimethylolpropane tri(meth)acrylate, silicone tri(meth)acrylate, 1,3,5-tri(meth)acryloylhexahydro-s-triazine, trimethylolethane tri(meth)acrylate, 1,1,1-trimethylolpropane tri(meth)acrylate, 1,2,3-trimethylolpropane tri(meth)acrylate, 1,1,1-trimethylolpropane tris((meth)acryloxypropionate), 1,2,3-trimethylolpropane tris((meth)acryloxypropionate), tris-(2-(meth)acryloxyethyl) isocyanurate and other trifunctional (meth)acrylic compounds; pentaerythritol tetra(meth)acrylate, pentaerythritol tetrakis((meth)acryloxypropionate) and other tetrafunctional (meth)acrylic compounds; etc. can be mentioned.

[0030] As the monofunctional compound, a monofunctional (meth)acrylic compound having one (meth)acryloyl group is preferred. Specific examples of the monofunctional (meth)acrylic compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, benzyl (meth)acrylate, glycidyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, n-octyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate (2-HPA), dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-trimethylphenyl (meth)acrylate, 4-chlorophenyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-(meth)acryloyloxyhexahydrophthalic acid, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalic acid, EO-modified phenol (meth)acrylate, EO-modified cresol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, PO-modified nonylphenol (meth)acrylate, ethoxylated-o-phenylphenol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-tridecafluorooctyl (meth)acrylate, and the like.

[0031] The radically polymerizable compound preferably contains a compound having an aromatic ring (hereinafter also referred to as an aromatic monomer). Thereby, the moisture permeability of the cured body tends to be further reduced.

[0032] When the radically polymerizable compound contains an aromatic monomer, the proportion of the aromatic monomer in the radically polymerizable compound may be, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and may be 5% by mass or more. Also, the proportion of the aromatic monomer in the radically polymerizable compound may be, for example, 70% by mass or less, preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less, and may be 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less. That is, the proportion of the aromatic monomer in the radically polymerizable compound may be, for example, 1 to 70% by mass, 1 to 60% by mass, 1 to 50% by mass, 1 to 40% by mass, 1 to 30% by mass, 1 to 20% by mass, 1 to 15% by mass, 1 to 10% by mass, 2 to 70% by mass, 2 to 60% by mass, 2 to 50% by mass, 2 to 40% by mass, 2 to 30% by mass, 2 to 20% by mass, 2 to 15% by mass, 2 to 10% by mass, 3 to 70% by mass, 3 to 60% by mass, 3 to 50% by mass, 3 to 40% by mass, 3 to 30% by mass, 3 to 20% by mass, 3 to 15% by mass, 3 to 10% by mass, 5 to 70% by mass, 5 to 60% by mass, 5 to 50% by mass, 5 to 40% by mass, 5 to 30% by mass, 5 to 20% by mass, 5 to 15% by mass, or 5 to 10% by mass.

[0033] Examples of the aromatic monomer include Compounds having one aromatic ring such as benzyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-trimethylphenyl (meth)acrylate, 4-chlorophenyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate (2-HPA), 2-(meth)acryloyloxyhexahydrophthalic acid, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalic acid, EO-modified phenol (meth)acrylate, EO-modified cresol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, PO-modified nonylphenol (meth)acrylate, ethoxylated-o-phenylphenol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, etc.; Compounds having two or more aromatic rings such as ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, etc.; etc. are mentioned.

[0034] From the viewpoint of further reducing the moisture permeability of the cured body and further improving the reliability of the organic EL element, as the aromatic monomer, a compound having two or more aromatic rings is preferable. The radically polymerizable compound preferably contains at least one selected from the group consisting of ethoxylated-o-phenylphenol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, and ethoxylated bisphenol A di(meth)acrylate as the aromatic monomer, and more preferably contains at least one selected from the group consisting of ethoxylated-o-phenylphenol (meth)acrylate and ethoxylated bisphenol A di(meth)acrylate.

[0035] The radically polymerizable compound contains an alicyclic monomer having a radically polymerizable group and an aliphatic hydrocarbon ring.

[0036] The aliphatic hydrocarbon ring of the alicyclic monomer may be a monocyclic ring or a condensed ring. Further, the aliphatic hydrocarbon ring may be a saturated hydrocarbon ring or an unsaturated hydrocarbon ring. The saturated hydrocarbon ring may be a cycloalkane ring. Examples of the unsaturated aliphatic hydrocarbon ring include a cycloalkene ring, a cycloalkadiene ring, a cycloalkatriene ring, etc., and a cycloalkene ring is preferable.

[0037] Examples of the cycloalkane ring include a cyclopentane ring, a cyclohexane ring, a tetrahydrodicyclopentadiene ring, a cycloheptane ring, a cyclooctene ring, a norbornane ring, an adamantane ring, etc.

[0038] Examples of the cycloalkene ring include a cyclopentene ring, a cyclohexene ring, a dihydrodicyclopentadiene ring, a cycloheptene ring, a cyclooctene ring, a norbornene ring, etc. From the viewpoint of excellent oxygen trap function at the unsaturated bond portion, the cycloalkene ring is preferably a cyclopentene ring, a cyclohexene ring or a dihydrodicyclopentadiene ring with large ring strain, and more preferably a cyclopentene ring or a dihydrodicyclopentadiene ring.

[0039] The alicyclic monomer may be a monofunctional compound having one radical polymerizable group, or may be a polyfunctional compound having two or more radical polymerizable groups. The number of radical polymerizable groups in the alicyclic monomer may be, for example, 1 to 6, preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 to 2.

[0040] The alicyclic monomer may be a compound having one aliphatic hydrocarbon ring, or may be a compound having two or more aliphatic hydrocarbon rings. The number of aliphatic hydrocarbon rings in the alicyclic monomer may be, for example, 1 to 6, preferably 1 to 4, more preferably 1 to 3, and still more preferably 1 to 2.

[0041] Examples of the alicyclic monomer include, for example, Saturated alicyclic monomers such as tricyclodecane dimethanol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate; Examples thereof include unsaturated alicyclic monomers such as dicyclopentenyl (meth)acrylate and dicyclopentenyl oxyethyl (meth)acrylate.

[0042] The proportion of the alicyclic monomer in the radically polymerizable compound may be, for example, 3% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more. Also, the proportion of the alicyclic monomer in the radically polymerizable compound may be, for example, 90% by mass or less, preferably 70% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less. That is, the proportion of the alicyclic monomer in the radically polymerizable compound may be, for example, 3 to 90% by mass, 3 to 70% by mass, 3 to 50% by mass, 3 to 40% by mass, 5 to 90% by mass, 5 to 70% by mass, 5 to 50% by mass, 5 to 40% by mass, 10 to 90% by mass, 10 to 70% by mass, 10 to 50% by mass, 10 to 40% by mass, 15 to 90% by mass, 15 to 70% by mass, 15 to 50% by mass, or 15 to 40% by mass.

[0043] The radically polymerizable compound preferably contains an acyclic monomer having a radically polymerizable group and no ring structure.

[0044] The number of radically polymerizable groups in the acyclic monomer may be, for example, 1 or more, preferably 2 or more. The number of radically polymerizable groups in the acyclic monomer may be, for example, 6 or less, preferably 4 or less, and more preferably 3 or less. The number of radically polymerizable groups in the acyclic monomer is particularly preferably 2. That is, the number of radically polymerizable groups in the acyclic monomer may be, for example, 1 to 6, 1 to 4, 1 to 3, 2 to 6, 2 to 4, or 2 to 3.

[0045] Examples of the non-cyclic monomer include a compound having a radically polymerizable group and a chain-like saturated hydrocarbon group (hereinafter also referred to as a chain monomer).

[0046] The number of carbon atoms of the chain-like saturated hydrocarbon group of the chain monomer is, for example, 2 or more, and may be 3 or more, 4 or more, 6 or more, 8 or more, or 10 or more. The number of carbon atoms of the chain-like saturated hydrocarbon group of the chain monomer may be, for example, 16 or less, and may be 15 or less, 14 or less, or 13 or less. That is, the number of carbon atoms of the chain-like saturated hydrocarbon group of the chain monomer may be, for example, 2 to 16, 2 to 15, 2 to 14, 2 to 13, 3 to 16, 3 to 15, 3 to 14, 3 to 13, 4 to 16, 4 to 15, 4 to 14, 4 to 13, 6 to 16, 6 to 15, 6 to 14, 6 to 13, 8 to 16, 8 to 15, 8 to 14, 8 to 13, 10 to 16, 10 to 15, 10 to 14, or 10 to 13.

[0047] The chain-like saturated hydrocarbon group of the chain monomer is preferably an alkanediyl group. The preferred range of the number of carbon atoms of the alkanediyl group is the same as the preferred range of the number of carbon atoms of the chain-like saturated hydrocarbon group.

[0048] When the radically polymerizable compound contains a chain monomer, the proportion of the chain monomer in the radically polymerizable compound may be, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, and may be 40% by mass or more, 50% by mass or more, or 55% by mass or more. Also, the proportion of the chain monomer in the radically polymerizable compound may be, for example, 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less. That is, the proportion of the chain monomer in the radically polymerizable compound may be, for example, 10 to 90% by mass, 10 to 85% by mass, 10 to 80% by mass, 20 to 90% by mass, 20 to 85% by mass, 20 to 80% by mass, 30 to 90% by mass, 30 to 85% by mass, 30 to 80% by mass, 40 to 90% by mass, 40 to 85% by mass, 40 to 80% by mass, 50 to 90% by mass, 50 to 85% by mass, 50 to 80% by mass, 55 to 90% by mass, 55 to 85% by mass, or 55 to 80% by mass.

[0049] Examples of the chain monomer include, for example, alkanediol di(meth)acrylates such as 1,4-butanediol di(meth)acrylate, 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, 1,12-dodecanediol di(meth)acrylate, 1,13-tridecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,15-pentadecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, neopentyl glycol dimethacrylate, 1,12-dodecanediol di(meth)acrylate; polyethylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate; polypropylene glycol di(meth)acrylates such as dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate; and the like.

[0050] The radically polymerizable compound preferably contains a compound having a fluoro group (hereinafter also referred to as a fluorine-containing monomer). Thereby, the surface free energy of the sealant becomes low, it becomes easy to follow fine irregularities, and the flatness of the coating film tends to be further improved.

[0051] When the radical polymerizable compound contains a fluorine-containing monomer, the proportion of the fluorine-containing monomer in the radical polymerizable compound may be, for example, 0.1% by mass or more, preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and may be 0.7% by mass or more, 0.9% by mass or more, or 1% by mass or more. Further, the proportion of the fluorine-containing monomer in the radical polymerizable compound may be, for example, 15% by mass or less, preferably 10% by mass or less, and may be 7% by mass or less, 5% by mass or less, 3% by mass or less, or 2% by mass or less. That is, the proportion of the fluorine-containing monomer in the radical polymerizable compound may be, for example, 0.1 to 15% by mass, 0.1 to 10% by mass, 0.1 to 7% by mass, 0.1 to 5% by mass, 0.1 to 3% by mass, 0.1 to 2% by mass, 0.3 to 15% by mass, 0.3 to 10% by mass, 0.3 to 7% by mass, 0.3 to 5% by mass, 0.3 to 3% by mass, 0.3 to 2% by mass, 0.5 to 15% by mass, 0.5 to 10% by mass, 0.5 to 7% by mass, 0.5 to 5% by mass, 0.5 to 3% by mass, 0.5 to 2% by mass, 0.7 to 15% by mass, 0.7 to 10% by mass, 0.7 to 7% by mass, 0.7 to 5% by mass, 0.7 to 3% by mass, 0.7 to 2% by mass, 0.9 to 15% by mass, 0.9 to 10% by mass, 0.9 to 7% by mass, 0.9 to 5% by mass, 0.9 to 3% by mass, 0.9 to 2% by mass, 1 to 15% by mass, 1 to 10% by mass, 1 to 7% by mass, 1 to 5% by mass, 1 to 3% by mass, or 1 to 2% by mass.

[0052] The number of fluoro groups in the fluorine-containing monomer may be, for example, 1 or more, preferably 2 or more, more preferably 3 or more. Further, the number of fluoro groups in the fluorine-containing monomer is not particularly limited, but may be, for example, 40 or less, preferably 30 or less. That is, the number of fluoro groups in the fluorine-containing monomer may be, for example, 1 to 40, 1 to 30, 2 to 40, 2 to 30, 3 to 40, or 3 to 30.

[0053] The fluorine atom content relative to the total amount of the fluorine-containing monomer may be, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 5% by mass or more. According to the fluorine-containing monomer satisfying such a content range, the above-described effects are more significantly exhibited. Further, the fluorine atom content relative to the total amount of the fluorine-containing monomer may be, for example, 75% by mass or less, preferably 70% by mass or less, more preferably 65% by mass or less. That is, the fluorine atom content relative to the total amount of the fluorine-containing monomer may be, for example, 1 to 75% by mass, 1 to 70% by mass, 1 to 65% by mass, 2 to 75% by mass, 2 to 70% by mass, 2 to 65% by mass, 5 to 75% by mass, 5 to 70% by mass, or 5 to 65% by mass.

[0054] The number of radically polymerizable groups possessed by the fluorine-containing monomer may be 1 or more. From the viewpoint of easily obtaining a cured product having a low glass transition temperature, the number of radically polymerizable groups possessed by the fluorine-containing monomer may be 1. Further, from the viewpoint of easily obtaining a cured product having a high glass transition temperature, the number of radically polymerizable groups possessed by the fluorine-containing monomer may be 2 or more. The upper limit of the number of radically polymerizable groups possessed by the fluorine-containing monomer is not particularly limited. The number of radically polymerizable groups possessed by the fluorine-containing monomer is, for example, 4 or less, and from the viewpoint of easily obtaining a cured product having excellent flexibility, it is preferably 3 or less, more preferably 2 or less.

[0055] Examples of the fluorine-containing monomer include 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-tridecafluorooctyl (meth)acrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-1,10-decanedi(meth)acrylate, and the like.

[0056] (Photoinitiator) The photoinitiator may be any initiator capable of polymerizing the above-mentioned radically polymerizable compound. One type of photoinitiator may be used alone, or two or more types may be used in combination.

[0057] Examples of the photoinitiator include benzophenone and its derivatives; benzyl and its derivatives; anthraquinone and its derivatives; benzoin type photoinitiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, etc.; acetophenone type photoinitiators such as diethoxyacetophenone, 4-tert-butyltrichloroacetophenone, etc.; 2-dimethylaminoethyl benzoate; p-dimethylaminoethyl benzoate; diphenyl disulfide; thioxanthone and its derivatives; camphorquinone type photoinitiators such as 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.; α-aminoalkylphenone type photoinitiators such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, etc.; Acylphosphine oxide type photoinitiators such as benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, benzoyldiethoxyphosphine oxide, 2,4,6-trimethylbenzoyldimethoxyphenylphosphine oxide, 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; Oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester; and the like.

[0058] As the photoinitiator, it can be cured using only visible light of 390 nm or more, and since it can be cured without damaging the organic EL element, an acylphosphine oxide type photoinitiator is preferred. As the acylphosphine oxide type photoinitiator, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is preferred in terms of further improving the transparency of the cured product and being able to be cured using only light of 395 nm or more. Examples of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide include "Omnirad TPO" manufactured by IGM Resins.

[0059] The content of the photoinitiator may be, for example, 0.05 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more with respect to 100 parts by mass of the radically polymerizable compound. Also, the content of the photoinitiator may be, for example, 10 parts by mass or less, preferably 8 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound. With such a content, it tends to be easy to ensure sufficient transparency of the encapsulant while obtaining sufficient sensitivity and curing rate of the sealant. That is, the content of the photopolymerization initiator may be, for example, 0.05 to 10 parts by mass, 0.05 to 8 parts by mass, 0.05 to 5 parts by mass, 0.5 to 10 parts by mass, 0.5 to 8 parts by mass, 0.5 to 5 parts by mass, 1 to 10 parts by mass, 1 to 8 parts by mass, 1 to 5 parts by mass, 2 to 10 parts by mass, 2 to 8 parts by mass, or 2 to 5 parts by mass with respect to 100 parts by mass of the radically polymerizable compound.

[0060] (Stable radical type compound) The stable radical type compound is a compound having a stable radical. The photopolymerization initiator may be used alone or in combination of two or more.

[0061] As the stable radical, a nitroxide radical (NO radical) is preferable. That is, as the stable radical type compound, a compound having a nitroxide radical is preferable. Since the nitroxide radical is excellent in compatibility and reactivity with the radically polymerizable compound, it can quickly capture radical species.

[0062] In the manufacturing process of the organic EL display device, since the organic EL element deteriorates by oxygen, it is managed at an oxygen concentration of less than 1 ppm, and the encapsulant for the organic EL element is also used at a low oxygen concentration. Here, a general phenolic antioxidant used for suppressing the polymerization of the radically polymerizable compound requires a reaction with oxygen in the process of exerting the polymerization suppression function. Therefore, it is difficult for the phenolic antioxidant to exert the polymerization suppression function in the encapsulant for the organic EL element. On the other hand, a stable radical type compound having a stable radical (especially a nitroxide radical) can capture radical species regardless of the presence or absence of oxygen, so the above-described effects can be obtained remarkably.

[0063] Examples of the stable radical type compound include 1-oxyl-2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl, etc. From the viewpoint of being incorporated into the cured body and being less likely to become outgas, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl is preferable, and 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl is more preferable.

[0064] The content of the stable radical type compound may be, for example, 1 mass ppm or more, preferably 10 mass ppm or more, more preferably 50 mass ppm or more, still more preferably 100 mass ppm or more, based on 100 parts by mass of the radically polymerizable compound. Also, the content of the stable radical type compound may be, for example, 15000 mass ppm or less, preferably 10000 mass ppm or less, more preferably 8000 mass ppm or less, still more preferably 6000 mass ppm or less, based on 100 parts by mass of the radically polymerizable compound. By using an appropriate amount of the stable radical type compound, the above-described effects can be exhibited more remarkably. That is, the content of the stable radical type compound may be, for example, 1 to 15000 mass ppm, 1 to 10000 mass ppm, 1 to 8000 mass ppm, 1 to 6000 mass ppm, 10 to 15000 mass ppm, 10 to 10000 mass ppm, 10 to 8000 mass ppm, 10 to 6000 mass ppm, 50 to 15000 mass ppm, 50 to 10000 mass ppm, 50 to 8000 mass ppm, 50 to 6000 mass ppm, 100 to 15000 mass ppm, 100 to 10000 mass ppm, 100 to 8000 mass ppm or 100 to 6000 mass ppm, based on 100 parts by mass of the radically polymerizable compound.

[0065] (Other components) The encapsulant of the present embodiment may further contain other components other than those described above. Examples of the other components include antioxidants, surfactants, sensitizers, etc.

[0066] The content of other components is not particularly limited, and may be, for example, 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and may also be 2 parts by mass or less or 1 part by mass or less, based on 100 parts by mass of the radically polymerizable compound.

[0067] The viscosity of the encapsulant of the present embodiment is preferably 3 mPa·s or more, more preferably 5 mPa·s or more. Also, the viscosity of the encapsulant of the present embodiment is preferably 50 mPa·s or less, more preferably 30 mPa·s or less. When the viscosity of the encapsulant is within the above range, the ejectability during coating by the inkjet method is further improved, and film formation tends to be easier. That is, the viscosity of the encapsulant may be, for example, 3 to 50 mPa·s, 3 to 30 mPa·s, 5 to 50 mPa·s, or 5 to 30 mPa·s.

[0068] In the present specification, the viscosity of the encapsulant indicates the value measured under the conditions of 25°C and 250 rpm using a cone plate viscometer (manufactured by Eiho Seiki Co., Ltd., model number: HB DV3T, etc.).

[0069] The sulfur atom concentration of the encapsulant of the present embodiment may be, for example, 100 ppm or less, preferably 50 ppm or less, more preferably 40 ppm or more. The sulfur atom concentration of the encapsulant of the present embodiment may also be, for example, 0.1 ppm or more, and may also be 1 ppm or more. That is, the sulfur atom concentration of the encapsulant of the present embodiment may be, for example, 0.1 to 100 ppm, 0.1 to 50 ppm, 0.1 to 40 ppm, 1 to 100 ppm, 1 to 50 ppm, or 1 to 40 ppm. With such a sulfur atom concentration, the deterioration of the organic EL element and the generation of dark spots are more significantly suppressed, and the reliability tends to be further improved.

[0070] The water concentration of the sealant of this embodiment may be, for example, 100 ppm or less, preferably 70 ppm or less, and more preferably 50 ppm or less. The water concentration of the sealant of this embodiment may also be, for example, 0.5 ppm or more, or 1 ppm or more. That is, the water concentration of the sealant of this embodiment may be, for example, 0.5 to 100 ppm, 0.5 to 70 ppm, 0.5 to 50 ppm, 1 to 100 ppm, 1 to 70 ppm, or 1 to 50 ppm. With such a water concentration, the above-mentioned effects tend to be more pronounced.

[0071] When the number of particles having a diameter of 1 μm or more present in 1 mL of the sealant of this embodiment is defined as a, and the number of particles having a diameter of 1 μm or more present in 1 mL of the sealant after heating at 80° C. for 16 hours is defined as b, it is preferable that ba is equal to or less than 10. With such a sealant, coating defects caused by particles are suppressed, and excellent dischargeability from a coating device and high flatness of the coating film after coating are achieved.

[0072] The above-mentioned a is preferably 10 or less, more preferably 5 or less, further preferably 3 or less, and may be 0.

[0073] The above b is preferably 10 or less, more preferably 5 or less, and further preferably 3 or less, and may be 0.

[0074] The sealant of this embodiment may contain particles of 1 μm or more, but preferably does not contain any (i.e., a is 0). Examples of particles include particles derived from polymers of radical polymerizable compounds, particles derived from foreign matter such as dust and dirt, and particles derived from dehydrating agents such as molecular sieves used in the manufacturing process of the sealant. The sealant of this embodiment may be a sealant that is substantially free of such particles, and may be one in which particles have been removed using a filter or the like.

[0075] In addition, in this specification, the number of particles indicates the value measured using a particle counter (manufactured by Rion Co., Ltd., light scattering type liquid particle detector, product number: KS-42B).

[0076] The acid value of the encapsulant of this embodiment is 0.15 (mgKOH / g) or less, preferably 0.13 (mgKOH / g) or less, and more preferably 0.10 (mgKOH / g) or less. Thereby, the above-mentioned effects are exhibited more remarkably. Also, the acid value of the encapsulant of this embodiment is 0.01 (mgKOH / g) or more, preferably 0.015 (mgKOH / g) or more, and more preferably 0.02 (mgKOH / g) or more. Thereby, the effect as a polymerization inhibitor of the acid component is exhibited more remarkably. That is, the acid value of the encapsulant of this embodiment may be, for example, 0.01 to 0.15 (mgKOH / g), 0.01 to 0.13 (mgKOH / g), 0.01 to 0.10 (mgKOH / g), 0.015 to 0.15 (mgKOH / g), 0.015 to 0.13 (mgKOH / g), 0.015 to 0.10 (mgKOH / g), 0.02 to 0.15 (mgKOH / g), 0.02 to 0.13 (mgKOH / g), or 0.02 to 0.10 (mgKOH / g).

[0077] The acid value of the encapsulant of this embodiment indicates the value measured by the following method. Weigh 2 g of the sample into a 50 mL toluene beaker, add 40 mL of 2-propanol, and stir for 5 minutes. After confirming the stability of the potential, use an automatic titrator COM 550 manufactured by Hiranuma Sangyo Co., Ltd. to determine the end point by potentiometric titration using a 0.1 mol / L 2-propanolic potassium hydroxide standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) as the titrant.

[0078] The manufacturing method of the encapsulant of this embodiment is not particularly limited, but it can be manufactured, for example, by the following method.

[0079] (Manufacturing method of encapsulant) The method for manufacturing the encapsulant of the present embodiment includes a pretreatment step of pretreating at least a part of the radically polymerizable compound by the following method (i) so that the acid value of the encapsulant becomes 0.01 to 0.15 (mgKOH / g), and a mixing step of mixing the radically polymerizable compound, a photopolymerization initiator, and a stable radical type compound having a stable radical to obtain an encapsulant. Further, the pretreatment step may further include pretreatment by the methods of (ii) and (iii). (i) Degassing treatment in an environment of 10 to 100 °C and 1000 Pa or less (ii) Distillation purification (iii) Column chromatography purification

[0080] According to the findings of the present inventors, the acid value of the encapsulant is caused by trace acid components in the radically polymerizable compound. Therefore, in the manufacturing method of the present embodiment, the acid value of the encapsulant is adjusted to a specific range by pretreating the radically polymerizable compound in the pretreatment step.

[0081] The pretreatment method in the pretreatment step includes (i), and may further include either (ii) or (iii).

[0082] <Pretreatment method (i)> The pretreatment method (i) is a method for degassing the radically polymerizable compound.

[0083] When there are multiple types of radically polymerizable compounds, in the pretreatment method (i), each radically polymerizable compound may be degassed individually, or multiple types of radically polymerizable compounds may be degassed simultaneously (degassing a mixture of multiple types of radically polymerizable compounds).

[0084] The temperature in the degassing treatment is 10 to 100 °C, preferably 30 to 90 °C, and more preferably 40 to 80 °C.

[0085] The pressure in the degassing treatment is 1000 Pa or less, preferably 800 Pa or less, more preferably 500 Pa or less. Also, the pressure in the degassing treatment may be, for example, 1 Pa or more, or may be 10 Pa or more. That is, the pressure in the degassing treatment may be, for example, 1 to 1000 Pa, 1 to 800 Pa, 1 to 500 Pa, 10 to 1000 Pa, 10 to 800 Pa, or 10 to 500 Pa.

[0086] The degassing treatment can be carried out, for example, in a container equipped with stirring means and connected to a vacuum pump and a vacuum gauge. During the degassing treatment, air bubbling (injection of air) may be carried out from the viewpoints of maintaining an appropriate degree of vacuum and suppressing the polymerization of the polymerizable compound.

[0087] <Pretreatment method (ii)> The pretreatment method (ii) is a method of purifying the radical polymerizable compound by distillation.

[0088] Suitable conditions for distillation purification include, for example, a temperature of 10 to 100 °C, a pressure of 0.1 MPa or less, etc.

[0089] Specific examples of distillation purification include, for example, the following methods. Note that the method of distillation purification is not limited to the following methods and may be appropriately selected from known distillation purification methods. The radical polymerizable compound is distilled using a rotary evaporator (manufactured by Tokyo Rika Kikai Co., Ltd., "Rotary Evaporator N-1000S") in a warm bath adjusted to 65 °C at a pressure of 0.05 MPa and a rotation speed of 50 r / min for 3 hours.

[0090] <Pretreatment method (iii)> The pretreatment method (iii) is a method of purifying the radical polymerizable compound by column chromatography.

[0091] Examples of column chromatography purification include column chromatography purification using silica gel as an adsorbent.

[0092] Specific examples of column chromatography purification include, for example, the following methods. Note that the method of column chromatography purification is not limited to the following methods, and may be appropriately selected from known column chromatography purification methods. Fill a glass column with silica gel, dissolve the radically polymerizable compound in a developing solvent of ethyl acetate:heptane = 2:98, place it on the silica gel, and separate and purify with the same developing solvent. Remove the solvent in the obtained solution to obtain the purified radically polymerizable compound.

[0093] In the pretreatment step, pretreatment is performed so that the acid value of the sealing agent is 0.01 to 0.15 (mgKOH / g). The pretreatment conditions and the like may be appropriately adjusted according to the blending amount of the radically polymerizable compound in the sealing agent and the like. That is, in the pretreatment step, the pretreatment conditions and the like may be appropriately adjusted according to the predetermined composition of the sealing agent.

[0094] The mixing step is a step of mixing a radically polymerizable compound, a photopolymerization initiator, and a stable radical type compound having a stable radical to obtain a sealing agent.

[0095] The mixing method in the mixing step is not particularly limited, and examples include mixing with a stirrer such as a three-one motor and mixing with a mix rotor.

[0096] Suitable mixing conditions in the mixing step include, for example, a temperature of 15 to 40°C and mixing for 1 hour or more.

[0097] <Sealing material> By curing the sealing agent of this embodiment, a cured body containing a polymer of a radically polymerizable compound can be obtained. This cured body may contain a stable radical as a stable radical type compound or its reaction product. This cured body can be suitably used as a sealing material for organic EL elements.

[0098] The encapsulant of this embodiment can be cured by light irradiation. The light source used for curing the encapsulant of this embodiment is not particularly limited. Examples of the light source include a halogen lamp, a metal halide lamp, a high-power metal halide lamp (containing indium, etc.), 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, an LED, and the like.

[0099] The above light sources have different emission wavelengths and energy distributions respectively. Therefore, the above light sources may be appropriately selected according to the reaction wavelength of the photoinitiator and the like. Also, natural light (sunlight) can also be a reaction initiation light source.

[0100] The irradiation by the light source may be direct irradiation or may be focused irradiation by a reflecting mirror, a fiber, or the like. Also, irradiation using a low-wavelength cut filter, a heat ray cut filter, a cold mirror, or the like may be used.

[0101] As a method for encapsulating an organic EL element using the encapsulant of this embodiment, for example, the following encapsulation methods and the like can be mentioned.

[0102] · Encapsulation method Prepare a substrate on which an organic EL element is installed, apply an encapsulant on the surface of the substrate on which the organic EL element is installed, and form a coating film of the encapsulant. Next, irradiate the coating film with light to form a sealing material made of a cured body of the encapsulant. Thereby, the organic EL element is encapsulated by the sealing material.

[0103] It is preferable to adopt an inkjet method for applying the encapsulant. In the manufacture of an organic EL display device, it is necessary to apply an encapsulant on a large-area substrate on which a plurality of organic EL elements are installed. Since the encapsulant of this embodiment can be applied while maintaining high ejectability even in the inkjet method, a uniform coating film can be formed on a large-area substrate.

[0104] The film thickness of the coating film of the sealing agent may be, for example, 1 μm or more, preferably 3 μm or more. Thereby, a sealing material having sufficient sealing ability is likely to be formed. Further, the film thickness of the coating film of the sealing agent may be, for example, 10 μm or less, preferably 9 μm or less. Thereby, miniaturization of the organic EL display device, reduction of manufacturing costs, etc. are expected. That is, the film thickness of the coating film of the sealing agent may be, for example, 1 to 10 μm, 1 to 9 μm, 3 to 10 μm, or 3 to 9 μm.

[0105] As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to the above embodiments. For example, the present invention can adopt various configurations other than the above. Further, the present invention may be a modification, improvement, etc. of the above embodiments within the range that can achieve the object of the present invention.

[0106] For example, the present invention may relate to an organic EL display device including an organic EL element and a sealing material for sealing the organic EL element. The sealing material includes a cured product of the above-described sealing agent. In this organic EL display device, the organic EL element may be a known organic EL element. Further, the configurations other than the organic EL element and the sealing material may be the same as those of a known organic EL display device.

Examples

[0107] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0108] In the examples and comparative examples, the following components were used. (A) Radical polymerizable compound (A-1) SR262 (1,12-dodecanediol dimethacrylate, manufactured by Arkema) (chain monomer) (A-2) BPE200 (ethoxylated bisphenol A dimethacrylate (compound represented by the following formula (m + n = 4), manufactured by Shin-Nakamura Chemical Co., Ltd.) (aromatic monomer)

Chemical formula

[0109] (B) Polymerization initiator (B-1) TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by IGM Resins)

[0110] (C) Stable radical type compound (C-1) TEMPO methacrylate (4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0111] In the examples and comparative examples, the following measurements and evaluations were performed.

[0112] (Measurement of acid value) Weighed 2 g of the sample into a 50 mL toluene beaker, added 40 mL of 2-propanol, and stirred for 5 minutes. After confirming the stability of the potential, the end point was determined by potentiometric titration using a 0.1 mol / L 2-propanolic potassium hydroxide standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) with an automatic titrator COM 550 manufactured by Hiranuma Sangyo Co., Ltd.

[0113] (Reliability evaluation of organic EL display device (organic EL reliability)) · Fabrication of organic EL display device for evaluation A glass substrate (700 μm thick) with a 30 mm ITO electrode was cleaned using acetone and isopropyl alcohol respectively. Then, the following compounds were sequentially vapor-deposited into thin films by vacuum vapor deposition method to obtain a substrate with a 2 mm square organic EL device composed of anode / hole injection layer / hole transport layer / light-emitting layer / Hole Blocking layer / electron transport layer / electron injection layer / cathode. The composition of each layer is as follows. Anode (ITO): 150 nm Hole injection layer (polymer HIL): 60 nm Hole transport layer (α-NPD): 30 nm Light-emitting layer (Ir(ppy)3 + CBP[6%]): 30 nm Hole Blocking layer (BAlq): 10 nm Electron transport layer (Alq3): 30 nm Electron injection layer (LiF): 0.8 nm Cathode (MgAg / IZO): 10 nm / 100 nm ITO is indium tin oxide, HIL is Hole Injection Layer, α-NPD is N,N’-diphenyl-N,N’-dinaphthylbenzidine, Ir(ppy)3 is iridium complex [tris(2-phenylpyridine)iridium], CBP is 4,4’-N,N’-dicarbazole-biphenyl, BAlq is bis(2-methyl-8-quinolinolato)(p-phenylphenolato)aluminum, Alq3 is tris(8-hydroxyquinolinolato)aluminum, LiF is lithium fluoride, and IZO is indium zinc oxide. Next, in a nitrogen atmosphere, a sealing agent was dropped using an inkjet device (product number: DMP2850) manufactured by Fujifilm to cover the 2 mm × 2 mm organic EL device, and a coating film with a thickness of 10 μm was obtained. Then, in a nitrogen atmosphere, an LED lamp (HOYA UV-LED LIGHT SOURCE H-4MLH200-V1) that emits light with a wavelength of 395 nm was used to irradiate with an integrated light quantity of 1,500 mJ / cm 2The light with a wavelength of 395 nm was irradiated onto the coating film so as to obtain a cured film. A mask (cover) having an opening of 10 mm × 10 mm was installed so as to cover the whole obtained cured film, and a SiN film was formed by plasma CVD method. The thickness of the formed SiN (inorganic film) was about 1 μm. Thus, a sealant for the organic EL element was obtained. The obtained sealant was bonded to a 30 mm × 30 mm × 0.7 mmt non-alkali glass (Eagle XG manufactured by Corning) using a 30 mm × 30 mm × 25 μmt transparent base material-less double-sided tape. Thus, an organic EL display device for evaluation was fabricated. ·Reliability test The organic EL display device for evaluation was left standing in a high temperature and high humidity environment of 85 °C and 85% RH for 500 hours. Before and after this high temperature and 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 (the image before the high temperature and high humidity treatment and the image after the high temperature and high humidity treatment) were analyzed with the image analysis software "Quick Grain" of Inotech to obtain the light emitting area. Then, the reduction rate (%) of the light emitting area before and after the high temperature and high humidity treatment was calculated.

[0114] (Examples 1 - 2, Comparative Example 1) The radical polymerizable compounds shown in Table 1 were mixed in the composition shown in Table 1, and degassing treatment was performed for the time shown in Table 1 in an environment of 60 °C and 800 Pa. Next, each component was mixed in the composition shown in Table 1 to prepare a sealant. The above measurements and evaluations were performed on the obtained sealant. The results are shown in Table 1.

[0115] (Examples 3 - 4, Comparative Example 2) The radical polymerizable compounds shown in Table 2 were mixed in the composition shown in Table 2, and degassing treatment was performed for the time shown in Table 2 in an environment of 60 °C and 800 Pa. Next, each component was mixed in the composition shown in Table 2 to prepare a sealant. The above measurements and evaluations were performed on the obtained sealant. The results are shown in Table 2.

[0116]

Table 1

[0117]

Table 2

Claims

1. A sealing agent for an organic electroluminescence device, comprising a radically polymerizable compound, a photopolymerization initiator, and a stable radical type compound having a stable radical, wherein the stable radical type compound includes 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl, and having an acid value of 0.01 to 0.15 (mgKOH / g).

2. A sealing material comprising a cured product of the sealing agent according to Claim 1.

3. An organic electroluminescence device, and the sealing material according to Claim 2 for sealing the organic electroluminescence device, comprising an organic electroluminescence display device.

4. A method for producing the sealing agent according to Claim 1, wherein at least a part of the radically polymerizable compound is degassed in an environment of 10 to 100°C and 1000 Pa or less in a pretreatment step so that the acid value of the sealing agent becomes 0.01 to 0.15 (mgKOH / g), and a mixing step of mixing the radically polymerizable compound, the photopolymerization initiator, and the stable radical type compound having a stable radical to obtain the sealing agent, including, wherein the stable radical type compound includes 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl, a method for producing a sealing agent for an organic electroluminescence device.

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