JP7705550B2 - Sealant for organic electroluminescence element, sealing material, and organic electroluminescence display device - Google Patents

Description

The present invention relates to a sealant for organic electroluminescent elements, a sealant material, and an organic electroluminescent display device.

Organic electroluminescence elements (hereinafter referred to as organic EL elements) have been attracting attention as elements capable of emitting light with high brightness. However, organic EL elements have the problem that they deteriorate due to oxygen and moisture, resulting in a decrease in their light-emitting properties. To solve this problem, technology is being developed to seal organic EL elements and prevent deterioration.

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

JP 2019-040872 A

Known sealants for organic EL elements include thermosetting sealants and photocurable sealants. Photocurable sealants do not require heating during sealing, so they have the advantage that they can form a sealant without exposing the organic EL element to high heat, and they suppress deformation and deterioration of the organic EL element due to high heat.

In recent years, the required characteristics of electronic devices have increased, and there is a demand for encapsulating materials that can achieve higher reliability for organic EL elements, for example.

However, with conventional photocurable sealants, it was difficult to adequately suppress the occurrence of dark spots during durability tests under high temperature and high humidity conditions.

Therefore, the present invention aims to provide a sealant for organic EL elements that can significantly suppress the occurrence of dark spots under high temperature and high humidity conditions. The present invention also aims to provide a sealant formed from the sealant for organic EL elements, and an organic EL display device including the sealant.

The present invention relates to, for example, the following items <1> to <11>.
<1> A sealant for an organic electroluminescence device, comprising: a radical polymerizable compound; a photopolymerization initiator; and a stable radical-type compound having a stable radical, wherein the radical polymerizable compound includes an unsaturated alicyclic monomer having a radical polymerizable group and an unsaturated aliphatic hydrocarbon ring.
<2> The sealant according to <1>, wherein the unsaturated aliphatic hydrocarbon ring is a cycloalkene ring.
<3> The sealant according to <1> or <2>, wherein the content of the unsaturated alicyclic monomer is 3 to 90 mass % based on the total amount of the radical polymerizable compound.
<4> The sealant according to any one of <1> to <3>, wherein the stable radical is a nitroxide radical.
<5> The sealant according to any one of <1> to <4>, wherein the content of the stable radical compound is 1 to 15,000 ppm by mass with respect to 100 parts by mass of the radical polymerizable compound.
<6> The sealant according to any one of <1> to <5>, wherein the radical polymerizable compound further contains an acyclic monomer having a radical polymerizable group and no ring structure.
<7> The sealant according to any one of <1> to <6>, wherein the radical polymerizable compound further contains an aromatic monomer having a radical polymerizable group and an aromatic ring.
<8> The sealant according to any one of <1> to <7>, wherein the radically polymerizable compound further contains a fluorine-containing monomer having a radically polymerizable group and a fluoro group.
<9> A sealing material comprising a cured product of the sealing agent according to any one of <1> to <8>.
<10> An organic electroluminescence display device comprising: an organic electroluminescence element; and the sealing material according to <9> that seals the organic electroluminescence element.

According to the present invention, there is provided a sealant for organic EL elements that can significantly suppress the occurrence of dark spots under high temperature and high humidity conditions. In addition, according to the present invention, there is provided a sealant formed from the sealant for organic EL elements, and an organic EL display device including the sealant.

A preferred embodiment of the present invention is described in detail below.

In this specification, the expression "X to Y" in the description of a numerical range means from X to Y, unless otherwise specified. For example, "1 to 5% by mass" means "from 1% by mass to 5% by mass."

In this specification, when a group (atomic group) is represented without specifying whether it is substituted or unsubstituted, it includes both unsubstituted and substituted groups. For example, an "alkyl group" includes not only an alkyl group that does not have a substituent (unsubstituted alkyl group), but also an alkyl group that has a substituent (substituted alkyl group).

In this specification, the term "(meth)acrylic" includes both acrylic and methacrylic. The same applies to similar terms such as "(meth)acrylate."

<Sealant>
The sealant of the present embodiment contains a radical polymerizable compound, a photopolymerization initiator, and a stable radical type compound having a stable radical. In the sealant of the present embodiment, the radical polymerizable compound includes an unsaturated alicyclic monomer having a radical polymerizable group and an unsaturated aliphatic hydrocarbon ring.

The sealant of this embodiment is for sealing organic electroluminescence elements. That is, the sealant of this embodiment is used to seal an organic EL element to manufacture an organic EL display device. The sealant of this embodiment is a photocurable sealant because it contains a photopolymerization initiator.

By sealing the organic EL element with the sealant of this embodiment, the occurrence of dark spots under high temperature and high humidity conditions is significantly suppressed.

The reason why the sealant of the present embodiment exhibits the above-mentioned effects is not necessarily limited, but the following reasons are considered.
According to the findings of the present inventors, in the sealant of this embodiment, the unsaturated aliphatic hydrocarbon ring in the unsaturated alicyclic monomer functions as an oxygen trap, so that polymerization inhibition caused by oxygen during polymerization is suppressed, and the amount of unreacted monomer in the cured body (sealant) is reduced. Therefore, in this embodiment, it is considered that the deterioration of the organic EL element and the occurrence of dark spots caused by the intrusion of the unreacted monomer through defects in the inorganic protective film on the organic EL element are suppressed.
Furthermore, in the sealant of the present embodiment, since the unsaturated alicyclic monomer has an unsaturated aliphatic hydrocarbon ring, it is believed that the unsaturated aliphatic hydrocarbon ring remaining in the cured body (sealant) functions as an oxygen trap, thereby suppressing deterioration of the organic EL element and the occurrence of dark spots due to the intrusion of oxygen.

In addition, the sealant of this embodiment has excellent dischargeability from an application device. Specifically, the sealant of this embodiment suppresses bending of the discharged liquid and variation in the amount of discharged liquid when discharged from the application device, and maintains good dischargeability. As a result, the sealant of this embodiment can form a coating film with significantly less unevenness in thickness and excellent flatness. In addition, the sealant of this embodiment can form a sealant that contributes to improving the reliability of organic EL elements.

The reason why the sealant of the present embodiment exhibits the above-mentioned effects is not necessarily limited, but the following reasons are considered.
According to the findings of the present inventors, when a conventional photocurable sealant is discharged from an application device, the discharged liquid may bend, the amount of the discharged liquid may vary, etc., which may cause uneven thickness in the coating film and reduce the flatness of the coating film. The cause of this is thought to be that the photocurable sealant is prone to unintended polymerization before use of the sealant (e.g., during storage, transportation, etc.), and fine particles generated by this polymerization narrow the flow path of the application device, causing the discharged liquid to bend, the amount of the discharged liquid to vary, etc.
The sealant of the present embodiment contains a stable radical compound, and thus, although it is a photocurable sealant, unintended polymerization before use (e.g., during storage, transportation, etc.) and generation of particles due to the polymerization are significantly suppressed. Therefore, the sealant of the present embodiment suppresses coating defects caused by particles, and realizes excellent dischargeability from a coating device and high flatness of the coating film after coating.

In addition, in the conventional photocurable sealant, during light irradiation, due to uneven thickness of the coating film, variation in the amount of irradiation, etc., reaction points such as photopolymerization initiator, radical species generated from the photopolymerization initiator, and radical species generated during polymerization may remain in the cured body. And, due to the presence of such reaction points, further polymerization may occur in the cured body after the sealing operation, and the cured body may shrink during curing. Usually, an inorganic protective film with a thickness of about 1 μm is provided between the organic EL element and the sealant (cured body of the sealant), but when curing shrinkage occurs, the inorganic protective film is loaded and easily cracks are generated, and the reliability of the organic EL element may be reduced due to the intrusion of water or oxygen through the crack.
The sealant of the present embodiment contains a stable radical type compound, so that the above-mentioned reaction points are unlikely to remain in the cured product, and further polymerization from the reaction points is also suppressed. In addition, the sealant of the present embodiment contains an unsaturated alicyclic monomer, so that unreacted monomers are unlikely to remain in the cured product as described above, so that the reaction points remain less, and further polymerization in the cured product is suppressed. Therefore, according to the sealant of the present embodiment, it is possible to form a sealant that is unlikely to cause deterioration due to reaction points, can suppress damage to the inorganic protective film due to curing shrinkage, and contributes to improving the reliability of organic EL elements.

(Radically polymerizable compound)
The radical polymerizable compound may be any compound that can be polymerized by an active species generated from a photopolymerization initiator described below. The radical polymerizable compound may be used alone or in combination of two or more kinds.

A radically polymerizable compound can be said to be a compound having a radically polymerizable group. Examples of the radically polymerizable group include a vinyl group, a (meth)acryloyl group, an allyl group, a vinyl ether group, a vinyl ester group, and a (meth)acrylamide group. Of these, a (meth)acryloyl group is particularly preferred.

In the sealant of this embodiment, the radically polymerizable compound includes an unsaturated alicyclic monomer having a radically polymerizable group and an unsaturated aliphatic hydrocarbon ring.

The unsaturated aliphatic hydrocarbon ring of the unsaturated alicyclic monomer may be a single ring or a condensed ring. Examples of the unsaturated aliphatic hydrocarbon ring include a cycloalkene ring, a cycloalkadiene ring, and a cycloalkatriene ring. From the viewpoint of more prominently exhibiting the above-mentioned effects, a cycloalkene ring is preferred.

Examples of cycloalkene rings include a cyclopentene ring, a cyclohexene ring, a dihydrodicyclopentadiene ring, a norbornene ring, a cycloheptene ring, and a cyclooctene ring. From the viewpoint of excellent reactivity of the unsaturated bond, the cycloalkene ring is preferably selected from the group consisting of a cyclopentene ring, a cyclohexene ring, a dihydrodicyclopentadiene ring, and a norbornene ring, and more preferably selected from the group consisting of a cyclopentene ring and a dihydrodicyclopentadiene ring.

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

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

Examples of unsaturated alicyclic monomers include dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyloxypropyloxyethyl (meth)acrylate, and (norborn-5-en-2-yl)methyl acrylate.

The proportion of the unsaturated alicyclic monomer in the radical 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 even more preferably 15% by mass or more. This makes the above-mentioned effect more pronounced. The proportion of the unsaturated alicyclic monomer in the radical 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 even more preferably 40% by mass or less. This makes the above-mentioned effect more pronounced.
That is, the proportion of the unsaturated alicyclic monomer in the radically polymerizable compound may be, for example, 3 to 90 mass%, 3 to 70 mass%, 3 to 50 mass%, 3 to 40 mass%, 5 to 90 mass%, 5 to 70 mass%, 5 to 50 mass%, 5 to 40 mass%, 10 to 90 mass%, 10 to 70 mass%, 10 to 50 mass%, 10 to 40 mass%, 15 to 90 mass%, 15 to 70 mass%, 15 to 50 mass%, or 15 to 40 mass%.

The radically polymerizable compound may contain multiple components, including an unsaturated alicyclic monomer.

The radical polymerizable compound preferably includes, 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, and preferably 2 to 4. The use of a polyfunctional compound tends to further improve photocurability.

From the viewpoint of obtaining a good balance of properties as a sealing material, a bifunctional compound having two radically polymerizable groups is preferred as the multifunctional compound.

The radical polymerizable compound may contain a monofunctional compound having one radical polymerizable group. From the viewpoint of easily adjusting the polymerization rate, the physical properties of the cured body, etc., it is preferable that the radical polymerizable compound contains a polyfunctional compound and a monofunctional compound.

In addition, the unsaturated alicyclic monomer may be a polyfunctional compound or a monofunctional compound.

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

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-butane Diol 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-trimethylsilyl ether, ethyl-3,13-dioxo-3,14-dioxa-5,12-diazahexadecane-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-phenylenedi(meth)acrylate, 1-phenyl-1,2-ethanediol di(meth)acrylate, polyoxyethyl-2,2-di(p-hydroxyphenyl)propionate 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. Bifunctional (meth)acrylic compounds such as 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, and 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-1,10-decane diacrylate;
Trifunctional (meth)acrylic compounds such as 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), and tris-(2-(meth)acryloxyethyl)isocyanurate;
tetrafunctional (meth)acrylic compounds such as pentaerythritol tetra(meth)acrylate and pentaerythritol tetrakis((meth)acryloxypropionate);
etc.

As the monofunctional compound, a monofunctional (meth)acrylic compound having one (meth)acryloyl group is preferable. Specific examples of monofunctional (meth)acrylic compounds 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-methoxyl (meth)acrylate, ...ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate, ethyl (meth)acrylate Diethyl (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, dicyclopentenyloxyethyl (meth)acrylate acrylate, dicyclopentanyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl (meth)acrylate, 4-chlorophenyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-(meth)acryloyloxyhexahydrophthalic acid, 2-(meth)acryloyloxyethyl-2-hydroxypropylphthalic acid, EO-modified phenol (meth)acrylate, EO-modified cresol (meth)acrylate, p)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.

It is preferable that the radical polymerizable compound contains a compound having an aromatic ring (hereinafter also referred to as an aromatic monomer). This tends to further reduce the moisture permeability of the cured body.

When the radical polymerizable compound contains an aromatic monomer, the ratio of the aromatic monomer in the radical 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 ratio of the aromatic monomer in the radical polymerizable compound may be, for example, 70% by mass or less, preferably 60% by mass or less, more preferably 50% by mass or less, and even 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 ratio of the aromatic monomer in the radical polymerizable compound may be, for example, 1 to 70 mass%, 1 to 60 mass%, 1 to 50 mass%, 1 to 40 mass%, 1 to 30 mass%, 1 to 20 mass%, 1 to 15 mass%, 1 to 10 mass%, 2 to 70 mass%, 2 to 60 mass%, 2 to 50 mass%, 2 to 40 mass%, 2 to 30 mass%, 2 to 20 mass%, 2 to 15 mass%, 2 to 10 mass%, 3 to 70 mass%, 3 to 60 mass%, 3 to 50 mass%, 3 to 40 mass%, 3 to 30 mass%, 3 to 20 mass%, 3 to 15 mass%, 3 to 10 mass%, 5 to 70 mass%, 5 to 60 mass%, 5 to 50 mass%, 5 to 40 mass%, 5 to 30 mass%, 5 to 20 mass%, 5 to 15 mass%, or 5 to 10 mass%.

Examples of aromatic monomers include:
Compounds having one aromatic ring, such as benzyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl (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-hydroxypropylphthalic 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, and m-phenoxybenzyl (meth)acrylate;
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, and bisphenol A epoxy di(meth)acrylate;
etc.

From the viewpoint of further reducing the moisture permeability of the cured body and further improving the reliability of the organic EL element, a compound having two or more aromatic rings is preferred as the aromatic monomer. The radical polymerizable compound preferably contains, as the aromatic monomer, 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, 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.

It is preferable that the radically polymerizable compound contains an acyclic monomer having a radically polymerizable group and no ring structure.

The number of radical polymerizable groups possessed by the acyclic monomer may be, for example, 1 or more, and is preferably 2 or more. The number of radical polymerizable groups possessed by the acyclic monomer may be, for example, 6 or less, preferably 4 or less, and more preferably 3 or less. That is, the number of radical polymerizable groups possessed by 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. It is particularly preferable that the number of radical polymerizable groups possessed by the acyclic monomer is 2.

Examples of acyclic monomers include compounds having a radically polymerizable group and a chain-like saturated hydrocarbon group (hereinafter also referred to as a chain-like monomer).

The number of carbon atoms in the chain saturated hydrocarbon group contained in 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 in the chain saturated hydrocarbon group contained in the chain monomer may be, for example, 16 or less, 15 or less, 14 or less, or 13 or less.
That is, the number of carbon atoms in the chain 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.

The linear saturated hydrocarbon group of the linear monomer is preferably an alkanediyl group. The preferred range of the carbon number of the alkanediyl group is the same as the preferred range of the carbon number of the linear saturated hydrocarbon group.

When the radical polymerizable compound contains a chain monomer, the proportion of the chain monomer in the radical 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 radical polymerizable compound may be, for example, 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, and may be 75% by mass or less.
That is, the proportion of the chain monomer in the radical polymerizable compound may be, for example, 10 to 90 mass%, 10 to 85 mass%, 10 to 80 mass%, 10 to 75 mass%, 20 to 90 mass%, 20 to 85 mass%, 20 to 80 mass%, 20 to 75 mass%, 30 to 90 mass%, 30 to 85 mass%, 30 to 80 mass%, 30 to 75 mass%, 40 to 90 mass%, 40 to 85 mass%, 40 to 80 mass%, 40 to 75 mass%, 50 to 90 mass%, 50 to 85 mass%, 50 to 80 mass%, 50 to 75 mass%, 55 to 90 mass%, 55 to 85 mass%, 55 to 80 mass%, or 55 to 75 mass%.

Examples of the chain monomer include
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, and neopentyl glycol di(meth)acrylate;
polyethylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate and triethylene glycol di(meth)acrylate;
Polypropylene glycol di(meth)acrylates such as dipropylene glycol di(meth)acrylate and tripropylene glycol di(meth)acrylate;
etc.

The radical polymerizable compound preferably contains a compound having a fluoro group (hereinafter also referred to as a fluorine-containing monomer). This lowers the surface free energy of the sealant, making it easier to conform to fine irregularities, and tends to further improve the flatness of the coating film.

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

The number of fluoro groups in the fluorine-containing monomer may be, for example, 1 or more, preferably 2 or more, and more preferably 3 or more. The number of fluoro groups in the fluorine-containing monomer is not particularly limited, but may be, for example, 40 or less, and 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.

The content of fluorine atoms 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, and more preferably 5% by mass or more. According to a fluorine-containing monomer that satisfies such a content range, the above-mentioned effect is more prominently exhibited. Furthermore, the content of fluorine atoms 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, and more preferably 65% by mass or less. That is, the content of fluorine atoms 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.

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

Examples of fluorine-containing monomers 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.

(Photopolymerization initiator)
The photopolymerization initiator may be any initiator capable of polymerizing the above-mentioned radical polymerizable compound. The photopolymerization initiator may be used alone or in combination of two or more kinds.

Examples of the photopolymerization initiator include
Benzophenone and its derivatives;
Benzil and its derivatives;
Anthraquinone and its derivatives;
Benzoin-type photopolymerization initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, and benzil dimethyl ketal;
Acetophenone-type photopolymerization initiators such as diethoxyacetophenone and 4-tert-butyltrichloroacetophenone;
2-Dimethylaminoethyl benzoate;
p-Dimethylaminoethyl benzoate;
Diphenyl disulfide;
Thioxanthone and its derivatives;
Camphorquinone-type photopolymerization initiators 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, and 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid chloride;
α-aminoalkylphenone type photopolymerization initiators such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1;
Acylphosphine oxide type photopolymerization initiators such as benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, benzoyldiethoxyphosphine oxide, 2,4,6-trimethylbenzoyldimethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiethoxyphenylphosphine oxide, and 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.

As the photopolymerization initiator, an acylphosphine oxide type photopolymerization initiator is preferred because it can be cured using only visible light of 390 nm or more and can be cured without damaging the organic EL element. As the acylphosphine oxide type photopolymerization initiator, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is preferred because it improves the transparency of the cured body and can 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.

The content of the photopolymerization initiator 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 even more preferably 2 parts by mass or more, relative to 100 parts by mass of the radical polymerizable compound. The content of the photopolymerization initiator 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, relative to 100 parts by mass of the radical polymerizable compound. With such a content, there is a tendency that it is easy to ensure sufficient transparency of the encapsulant while obtaining sufficient sensitivity and curing speed of the encapsulant.
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, relative to 100 parts by mass of the radical polymerizable compound.

(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 kinds.

As a stable radical, a nitroxide radical (NO radical) is preferred. In other words, as a stable radical type compound, a compound having a nitroxide radical is preferred. Nitroxide radicals have excellent compatibility and reactivity with radical polymerizable compounds, so they can quickly capture radical species.

In the manufacturing process of organic EL display devices, the organic EL elements are deteriorated by oxygen, so the oxygen concentration is controlled at a low level of less than 1 ppm, and the sealant for the organic EL elements is also used at a low oxygen concentration. Here, the general phenol-based antioxidants used to inhibit the polymerization of radically polymerizable compounds require a reaction with oxygen in the process of exerting their polymerization inhibition function. For this reason, it is difficult for phenol-based antioxidants to exert their polymerization inhibition function in sealants for organic EL elements. In contrast, stable radical-type compounds having stable radicals (especially nitroxide radicals) can capture radical species regardless of the presence or absence of oxygen, so the above-mentioned effects can be obtained significantly.

Examples of stable radical compounds 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., and from the viewpoint of being less likely to be incorporated into the cured body and become an outgas, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl is preferred, with 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl being more preferred.

The content of the stable radical type compound may be, for example, 1 ppm by mass or more, preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, and even more preferably 100 ppm by mass or more, relative to 100 parts by mass of the radical polymerizable compound. The content of the stable radical type compound may be, for example, 15000 ppm by mass or less, preferably 10000 ppm by mass or less, more preferably 8000 ppm by mass or less, and even more preferably 6000 ppm by mass or less, relative to 100 parts by mass of the radical polymerizable compound. By using an appropriate amount of the stable radical type compound, the above-mentioned effect is more significantly achieved.
That is, the content of the stable radical type compound may be, for example, 1 to 15000 ppm by mass, 1 to 10000 ppm by mass, 1 to 8000 ppm by mass, 1 to 6000 ppm by mass, 10 to 15000 ppm by mass, 10 to 10000 ppm by mass, 10 to 8000 ppm by mass, 10 to 6000 ppm by mass, 50 to 15000 ppm by mass, 50 to 10000 ppm by mass, 50 to 8000 ppm by mass, 50 to 6000 ppm by mass, 100 to 15000 ppm by mass, 100 to 10000 ppm by mass, 100 to 8000 ppm by mass, or 100 to 6000 ppm by mass.

(Other ingredients)
The sealant of the present embodiment may further contain other components in addition to those described above, such as an antioxidant, a surfactant, a sensitizer, and the like.

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 be 2 parts by mass or less or 1 part by mass or less, relative to 100 parts by mass of the radical polymerizable compound.

The viscosity of the sealant of the present embodiment is preferably 3 mPa·s or more, more preferably 5 mPa·s or more. The viscosity of the sealant of the present embodiment is preferably 50 mPa·s or less, more preferably 30 mPa·s or less. When the viscosity of the sealant is within the above range, the ejection properties during application by the inkjet method tend to be further improved, and the formation of a coating film tends to be easier.
That is, the viscosity of the sealant of the present embodiment 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.

In this specification, the viscosity of the sealant indicates the value measured using a cone-plate type viscometer (manufactured by Eiko Seiki Co., Ltd., product number: HB DV3T, etc.) at conditions of 25°C and 250 rpm.

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

When the number of particles with a diameter of 1 μm or more present in 1 mL of the sealant of this embodiment is taken as a, and the number of particles with a diameter of 1 μm or more present in 1 mL of the sealant after heating at 80° C. for 16 hours is taken as b, it is preferable that b-a is 10 or less. With such a sealant, coating defects caused by particles are suppressed, and excellent discharge properties from the coating device and high flatness of the coating film after coating are achieved.

The above a is preferably 10 or less, more preferably 5 or less, even more preferably 3 or less, and may be 0.

The above b is preferably 10 or less, more preferably 5 or less, even more preferably 3 or less, and may be 0.

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 these particles, and may be one in which particles have been removed using a filter or the like.

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

By curing the sealant of this embodiment, a cured product containing a polymer of a radically polymerizable compound can be obtained. This cured product may contain a stable radical as a stable radical type compound or its reaction product. This cured product can be suitably used as a sealant for organic EL elements.

The sealant of this embodiment can be cured by light irradiation. The light source used to cure the sealant of this embodiment is not particularly limited. Examples of light sources include halogen lamps, metal halide lamps, high-power metal halide lamps (containing indium, etc.), low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, xenon excimer lamps, xenon flash lamps, LEDs, etc.

The above light sources each have different emission wavelengths and energy distributions. Therefore, the light source may be selected appropriately depending on the reaction wavelength of the photopolymerization initiator. Natural light (sunlight) can also be a reaction initiation light source.

Irradiation from a light source may be direct irradiation or may be focused irradiation using a reflector, fiber, etc. Irradiation may also be using a low wavelength cut filter, a heat ray cut filter, a cold mirror, etc.

Methods for sealing an organic EL element using the sealant of this embodiment include, for example, the following sealing methods.

Sealing method: A substrate on which an organic EL element is mounted is prepared, and a sealant is applied to the surface of the substrate on which the organic EL element is mounted to form a coating film of the sealant. Next, the coating film is irradiated with light to form a sealant made of a cured product of the sealant. This seals the organic EL element with the sealant.

It is preferable to use an inkjet method for applying the sealant. In the manufacture of organic EL display devices, it is necessary to apply the sealant onto a large-area substrate on which multiple organic EL elements are mounted. The sealant of this embodiment can be applied while maintaining high ejection properties even when applied by the inkjet method, so that a uniform coating film can be formed on a large-area substrate.

The thickness of the sealant coating may be, for example, 1 μm or more, and preferably 3 μm or more. This makes it easier to form a sealant with sufficient sealing ability. The thickness of the sealant coating may be, for example, 10 μm or less, and preferably 9 μm or less. This is expected to lead to smaller organic EL display devices and reduced manufacturing costs. That is, the thickness of the sealant coating may be, for example, 1 to 10 μm, 1 to 9 μm, 3 to 10 μm, or 3 to 9 μm.

Although the above describes a preferred embodiment of the present invention, the present invention is not limited to the above embodiment. For example, the present invention can adopt various configurations other than those described above. Furthermore, the present invention may be a modification or improvement of the above embodiment within the scope of achieving the object of the present invention.

For example, the present invention may relate to an organic EL display device including an organic EL element and a sealant that seals the organic EL element. The sealant includes a hardened product of the sealant described above. In this organic EL display device, the organic EL element may be a known organic EL element. Furthermore, the configuration other than the organic EL element and the sealant may be the same as that of a known organic EL display device.

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

（Ａ－３）ＬＩＮＣ－１６２Ａ（２，２，３，３，４，４，５，５，６，６，７，７，８，８，９，９－ヘキサデカフルオロ－１，１０－デカンジアクリレート、共栄社化学社製）（含フッ素モノマー）
（Ａ－４）ＦＡ－５１２ＡＳ（ジシクロペンテニルオキシエチルアクリレート、昭和電工マテリアルズ社製）（不飽和脂環式モノマー）
（Ａ－５）ＩＢＸＡ（イソボルニルアクリレート、大阪有機化学工業社製） In the examples and comparative examples, the following components were used.
(A) Radically 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)

(A-3) LINC-162A (2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-1,10-decane diacrylate, manufactured by Kyoeisha Chemical Co., Ltd.) (fluorine-containing monomer)
(A-4) FA-512AS (dicyclopentenyloxyethyl acrylate, manufactured by Showa Denko Materials Co., Ltd.) (unsaturated alicyclic monomer)
(A-5) IBXA (isobornyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.)

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

(C) Stable Radical Compound (C-1) TEMPO methacrylate (4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl, manufactured by Tokyo Chemical Industry Co., Ltd.)

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

(Unreacted Monomer Concentration)
The sealant was sandwiched between PET films with 100 μm spacer tape attached, and irradiated with light having a wavelength of 395 nm by an LED lamp (UV-LED LIGHT SOURCE H-4MLH200-V1 manufactured by HOYA Corporation) emitting light having a wavelength of 395 nm so that the accumulated light amount was 1,500 mJ/cm ^2. The obtained cured film was peeled off from the PET film, cut into 5 mm squares, and 0.5 g was weighed into a 10 mL vial. 5 mL of acetone was poured into the vial, ultrasonicated for 30 minutes, and allowed to stand in an atmosphere of 23 ° C. for 16 hours. After standing, the mixture was filtered with a 0.45 μm membrane filter, measured by gas chromatography, and the unreacted monomer concentration was quantified from the peak area of the obtained chart. The specifications of the gas chromatograph can be appropriately determined, and for example, the following can be adopted.
・Equipment: Agilent 7890B
Col.: HP-5MS 60m x φ0.25mm x film thickness 0.25μm
Col. Temp.: 40° C. for 1 min, then heated to 180° C. at a rate of 20° C./min, then heated to 300° C. at a rate of 10° C./min, and held for 50 min. Inj. Temp.: 300° C.
・Det. Temp. :300℃
Flow: 1 mL/min x 22 min, then 0.1 mL/min, then 2 mL/min, split 1/20
Inj: 1 μL

(Reliability evaluation of organic EL display devices (organic EL reliability))
- Preparation of an organic EL display device for evaluation A 30 mm square glass substrate (700 μm thick) with an ITO electrode was washed with acetone and isopropanol, respectively. After that, the following compounds were sequentially deposited by vacuum deposition to form thin films, to obtain a substrate having a 2 mm square organic EL element consisting of an anode/hole injection layer/hole transport layer/light-emitting layer/hole blocking layer/electron transport layer/electron injection layer/cathode. The composition of each layer is as follows.
Anode (ITO): 150nm
Hole injection layer (polymer HIL): 60 nm
Hole transport layer (α-NPD): 30nm
Light-emitting layer (Ir(ppy) ₃ + CBP [6%]): 30 nm
Hole blocking layer (BAlq): 10nm
Electron transport layer (Alq ₃ ): 30 nm
Electron injection layer (LiF): 0.8nm
Cathode (MgAg/IZO): 10nm/100nm
ITO is indium tin oxide, HIL is hole injection layer, α-NPD is N,N'-diphenyl-N,N'-dinaphthylbenzidine, Ir(ppy) ₃ is an 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, under a nitrogen atmosphere, a Fujifilm inkjet device (product number: DMP2850) was used to deposit droplets of the sealant so as to cover the organic EL element of 2 mm x 2 mm, to obtain a coating film of 10 μm in thickness. Thereafter, under a nitrogen atmosphere, the coating film was irradiated with light of 395 nm in wavelength by an LED lamp (HOYA UV-LED LIGHT SOURCE H-4MLH200-V1) emitting light of 395 nm in wavelength so as to obtain an integrated light quantity of 1,500 mJ/cm ^2. This resulted in a cured film. A mask (cover) having an opening of 10 mm x 10 mm was placed so as to cover the entirety of the obtained cured film, and a SiN film was formed by plasma CVD. The thickness of the formed SiN (inorganic film) was about 1 μm. This resulted in a sealed body of the organic EL element.
The obtained sealed body was attached to a non-alkali glass (Eagle XG manufactured by Corning) having a size of 30 mm×30 mm×0.7 mmt using a transparent substrate-less double-sided tape having a size of 30 mm×30 mm×25 μmt, thereby producing an organic EL display device for evaluation.
Reliability test The organic EL display device for evaluation was left in a high-temperature, high-humidity environment of 85°C and 85% RH for 500 hours. Before and after this high-temperature, high-humidity treatment, a current was passed through the organic EL display device for evaluation, and the light-emitting surface was photographed. The photographed images (images before and after the high-temperature, high-humidity treatment) were analyzed using Innotek's image analysis software "Quick Grain" to determine the light-emitting area. The reduction rate (%) of the light-emitting area before and after the high-temperature, high-humidity treatment was calculated.

(Examples 1 to 4)
A sealant was produced by mixing the components according to the composition shown in Table 1. The above-mentioned measurements and evaluations were carried out on the obtained sealant. The results are shown in Table 1.

(Comparative Examples 1 to 3)
A sealant was produced by mixing the components according to the composition shown in Table 2. The above-mentioned measurements and evaluations were carried out on the obtained sealant. The results are shown in Table 2.

As shown in Tables 1 and 2, the sealants of Examples 1 to 4 had significantly lower unreacted monomer concentrations than the sealant of the comparative example. Furthermore, it was confirmed that the organic EL display devices in which the organic EL elements were sealed with the sealants of Examples 1 to 4 had significantly reduced dark spot occurrence and significantly improved reliability compared to the organic EL display devices in which the organic EL elements were sealed with the sealant of the comparative example.

Claims (9)

The composition contains a radical polymerizable compound, a photopolymerization initiator, and a stable radical type compound having a stable radical,
the radical polymerizable compound contains an unsaturated alicyclic monomer having a radical polymerizable group and an unsaturated aliphatic hydrocarbon ring,
The stable radical compound includes 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl.
Sealant for organic electroluminescence devices. The sealant according to claim 1, wherein the unsaturated aliphatic hydrocarbon ring is a cycloalkene ring. The sealant according to claim 1, wherein the content of the unsaturated alicyclic monomer is 3 to 90 mass% based on the total amount of the radical polymerizable compound. The sealant according to claim 1, wherein the content of the stable radical compound is 1 to 15,000 ppm by mass relative to 100 parts by mass of the radical polymerizable compound. The sealant according to claim 1, wherein the radically polymerizable compound further contains an acyclic monomer having a radically polymerizable group and no ring structure. The sealant according to claim 1, wherein the radically polymerizable compound further comprises an aromatic monomer having a radically polymerizable group and an aromatic ring. The sealant according to claim 1, wherein the radically polymerizable compound further contains a fluorine-containing monomer having a radically polymerizable group and a fluoro group. A sealant comprising a cured product of the sealant according to any one of claims 1 to 7. An organic electroluminescence element;
The sealing material according to claim 8 for sealing the organic electroluminescence element;
An organic electroluminescence display device comprising: