Curable composition, cured film, organic electroluminescent device and producing method thereof

Abstract

To provide a curable composition capable of forming a cured matter having low dielectric constant and sufficiently high glass transition point.SOLUTION: A curable composition contains a polymerizable compound and a polymerization initiator, wherein the polymerizable compound contains a compound (A1) represented by formula (1): R1-X1-R2 (in formula (1), R1 and R2 are independently either substituted or unsubstituted alicyclic oxiranyl groups, and X1 is a bivalent hydrocarbon group or a halogenated hydrocarbon group), a compound (A2) which is a multifunctional polymerizable compound (excluding compound (A1)), and a compound (A3) which is a monofunctional polymerizable compound having one oxetanyl group per molecule, wherein the total amount of compounds (A1), (A2), and (A3) is at least 85 mass% with respect to the total amount of the polymerizable compound in the curable composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable composition, a cured film, an organic EL element, and a method for manufacturing the same.

Background Art

[0002] An organic electroluminescence element (organic EL element) is a light-emitting element having a laminated structure including an anode, an organic light-emitting layer, and a cathode. Organic EL elements are widely used in various applications such as display devices and lighting devices.

[0003] The organic light-emitting layer included in an organic EL element is liable to deteriorate due to contact with moisture and oxygen. For example, an area that does not emit light partially (hereinafter also referred to as a "dark spot") may be formed due to moisture that has entered the element during long-term driving, or the light-emitting characteristics may deteriorate due to contact with moisture and oxygen. Therefore, conventionally, in an organic EL element, a sealing structure for sealing the organic light-emitting layer is provided so that the organic light-emitting layer does not come into contact with moisture and oxygen (see, for example, Patent Documents 1 to 4).

[0004] Patent Document 1 discloses forming a sealing structure that covers an organic light-emitting layer with a curable composition containing a polymerizable compound in which two or three vinyl groups are bonded to a naphthalene ring and a polymerization initiator.

[0005] Patent Document 2 discloses a sealing agent for an organic EL display element containing a cationically polymerizable compound and a cationic polymerization initiator, and as the cationically polymerizable compound, a cycloalkene oxide type alicyclic epoxy compound and a compound having a biphenyl skeleton and an epoxy group or an oxetanyl group.

[0006] Patent Documents 3 and 4 disclose forming a sealing structure of an organic EL element by curing a sealing agent composition containing an alicyclic epoxy compound, a monofunctional or polyfunctional oxetane compound, and an aliphatic epoxy compound as polymerizable compounds.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] In the encapsulation structure of an organic EL element, a laminate of an inorganic encapsulation layer / an organic encapsulation layer / an inorganic encapsulation layer is generally adopted. When forming such a laminate, it is performed by laminating an inorganic encapsulation layer (for example, a nitride film), an organic encapsulation layer, and an inorganic encapsulation layer in this order. In such a case, if the glass transition temperature (Tg) of the organic encapsulation layer is low, when an inorganic encapsulation layer is formed on the organic encapsulation layer, distortion may occur in the organic encapsulation layer, which may cause crack generation.

[0009] In addition, in an organic EL light-emitting device adopting a touch panel method, a touch sensor is disposed on a substrate. When the dielectric constant of the encapsulation structure (particularly the organic encapsulation layer) is high in the touch panel method, malfunction may occur when the touch panel is used. Therefore, it is desired that the organic encapsulation layer of the encapsulation structure has a low dielectric constant, but reducing the dielectric constant and increasing the Tg of the cured film are in a trade-off relationship, and when attempting to reduce the dielectric constant of the cured film, the Tg increases.

[0010] The present invention has been made in view of the above problems, and a main object thereof is to provide a curable composition that can form a cured product having a low dielectric constant and a sufficiently high glass transition temperature.

Means for Solving the Problems

[0011] According to the present invention, there are provided the following curable composition, cured film, organic EL element and method for producing the same, and compound.

[0012] 〔1〕A curable composition containing a polymerizable compound and a polymerization initiator, wherein the polymerizable compound has the following formula (1): R 1 -X 1 -R 2 …(1) (In formula (1), R 1 and R 2 are each independently a substituted or unsubstituted alicyclic oxiranyl group. X 1 is a divalent hydrocarbon group or a halogenated hydrocarbon group.) It includes a compound (A1) represented by the formula, a polyfunctional polymerizable compound (excluding the compound (A1)), and a monofunctional polymerizable compound having one oxetanyl group in one molecule, and the total amount of the compound (A1), the compound (A2), and the compound (A3) is 85% by mass or more based on the total amount of the polymerizable compound. A curable composition. 〔2〕A curable composition containing a polymerizable compound and a polymerization initiator, wherein the polymerizable compound includes a compound represented by the above formula (1), a polyfunctional polymerizable compound (excluding the compound (A1)), and a monofunctional polymerizable compound, and the dielectric constant of the cured product of the curable composition at 25°C and a frequency of 250 kHz is 2.70 or less, and the glass transition temperature of the cured product is 85°C or higher. A curable composition. 〔3〕A cured film formed using the curable composition of the above 〔1〕 or 〔2〕. 〔4〕An organic EL element including an organic light-emitting layer and an organic encapsulation layer for encapsulating the organic light-emitting layer, wherein the organic encapsulation layer is formed using the curable composition of the above 〔1〕 or 〔2〕. 〔5〕 A method for manufacturing an organic EL element including an organic light-emitting layer and an organic encapsulation layer for encapsulating the organic light-emitting layer, the method including: a step of applying the curable composition of the above [1] or [2] onto a light-emitting layer formation surface of a substrate on which the organic light-emitting layer is formed; and a step of forming the organic encapsulation layer by irradiating radiation to cure the curable composition.

Advantages of the Invention

[0013] According to the curable composition of the present invention, a cured product having a low dielectric constant and a sufficiently high glass transition temperature can be obtained.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, matters related to the embodiments will be described in detail. In this specification, a numerical range described using "~" means that the numerical values described before and after "~" are included as the lower limit value and the upper limit value.

[0015] In this specification, "hydrocarbon group" means a group including a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. "Chain hydrocarbon group" means a straight-chain hydrocarbon group and a branched hydrocarbon group that do not include a cyclic structure in the main chain and are composed only of a chain structure. However, the chain hydrocarbon group may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that includes only the structure of an alicyclic hydrocarbon as the ring structure and does not include an aromatic ring structure. However, the alicyclic hydrocarbon group does not necessarily have to be composed only of the structure of an alicyclic hydrocarbon, and those having a chain structure in a part thereof are also included. "Aromatic hydrocarbon group" means a hydrocarbon group that includes an aromatic ring structure as the ring structure. However, the aromatic hydrocarbon group does not necessarily have to be composed only of the aromatic ring structure, and a part thereof may include a chain structure or an alicyclic hydrocarbon structure. Note that the ring structures of the alicyclic hydrocarbon group and the aromatic hydrocarbon group may have a substituent composed of a hydrocarbon structure.

[0016] 《Curable Composition》 The curable composition of the present disclosure (hereinafter also referred to as "this composition") contains a polymerizable compound and a polymerization initiator. The composition of the first embodiment in this composition (hereinafter also referred to as "the first composition") contains, as the polymerizable compound, the following compound (A1), compound (A2), and compound (A3). · Compound (A1): A compound represented by the following formula (1) R 1 -X 1 -R 2 …(1) (In formula (1), R 1 and R 2 are each independently a substituted or unsubstituted alicyclic oxiranyl group. X 1 is a divalent hydrocarbon group or a halogenated hydrocarbon group.) · Compound (A2): A polyfunctional polymerizable compound (excluding compound (A1).) · Compound (A3): A monofunctional polymerizable compound having one oxetanyl group in one molecule

[0017] Each component contained in the first composition and other components blended as necessary will be described below. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0018] <Polymerizable compound> The polymerizable compound is a general term for compounds that cure by irradiation with radiation or application of heat. The polymerizable compound has one or more functional groups (hereinafter also referred to as "polymerizable functional groups") that polymerize by irradiation with radiation or application of heat in one molecule.

[0019] As the polymerizable compound, a compound having one or more functional groups having cationic polymerizability (hereinafter also referred to as "cationic polymerizable groups") as the polymerizable functional group can be preferably used. Examples of the cationic polymerizable group include an oxetanyl group, an oxiranyl group, a vinyl ether group, etc. From the viewpoint of polymerization, a compound having an oxetanyl group or an oxiranyl group can be preferably used as the polymerizable compound.

[0020] The molecular weight of the polymerizable compound is, for example, 50 to 800, preferably 70 to 600, and more preferably 100 to 500, in terms of being easy to adjust to a viscosity suitable for inkjet coating.

[0021] The first composition contains, as the polymerizable compound, a monofunctional compound having one polymerizable functional group in one molecule and a polyfunctional compound having two or more polymerizable functional groups in one molecule. Among the polymerizable compounds contained in the first composition, compound (A1) and compound (A2) are polyfunctional polymerizable compounds, and compound (A3) is a monofunctional polymerizable compound. Hereinafter, compound (A1) to compound (A3) will be described respectively.

[0022] · Compound (A1) Compound (A1) is a compound represented by the above formula (1). In the above formula (1), R 1 or R 2 Preferred specific examples of the substituted or unsubstituted alicyclic oxiranyl group represented by include a group represented by the following formula (1a).

Chemical formula

[0023] In the above formula (1a), the alkyl group having 1 to 6 carbon atoms represented by R 7 may be linear or branched. Examples of the aryl group having 6 to 20 carbon atoms represented by R 7 include a phenyl group, a methylphenyl group, an ethylphenyl group, a dimethylphenyl group, a diethylphenyl group, and the like. R 7 Among these, an alkyl group having 1 to 3 carbon atoms or a phenyl group is preferable. n is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0.

[0024] From the viewpoint of reactivity to radiation or heat, R 1and R 2 is each preferably a substituted or unsubstituted 3,4-epoxycyclohexyl group, and more preferably a 3,4-epoxycyclohexyl group, among the above.

[0025] In the above formula (1), X 1 Examples of the divalent hydrocarbon group represented by include a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, and a divalent aromatic hydrocarbon group. Specific examples of these include, as the divalent chain hydrocarbon group, a linear or branched divalent saturated hydrocarbon group having 1 to 20 carbon atoms and a linear or branched divalent unsaturated hydrocarbon group having 2 to 20 carbon atoms. Among these, the divalent chain hydrocarbon group represented by X 1 is preferably a linear or branched divalent saturated hydrocarbon group having 1 to 20 carbon atoms.

[0026] Examples of the divalent alicyclic hydrocarbon group include a group obtained by removing two hydrogen atoms from the ring portion or chain portion of an alicyclic hydrocarbon having a saturated aliphatic ring or unsaturated aliphatic ring having 3 to 20 carbon atoms. Specific examples of the ring of the divalent alicyclic hydrocarbon group include monocyclic saturated alicyclic hydrocarbons such as cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring; monocyclic saturated alicyclic hydrocarbons such as cyclobutene ring, cyclopentene ring, cyclohexene ring, cycloheptene ring, cyclooctene ring; polycyclic saturated alicyclic hydrocarbons such as decahydronaphthalene ring, octahydronaphthalene ring, norbornane ring, bicyclo[2.2.2]octane ring; polycyclic unsaturated alicyclic hydrocarbons such as norbornene ring, tetracyclo[6.2.1.1 3,6 .0 2,7 dodeca-4-ene and the like; and the like.

[0027] Examples of the divalent aromatic hydrocarbon group include a group obtained by removing two hydrogen atoms from the ring portion or chain portion of an aromatic hydrocarbon having a monocyclic or condensed ring (for example, benzene ring, naphthalene ring, anthracene ring).

[0028] X 1Examples of the divalent halogenated hydrocarbon group represented by include groups in which one or more hydrogen atoms in the above-described divalent hydrocarbon group are substituted with halogen atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

[0029] In terms of being able to achieve both a lower dielectric constant and a higher Tg in the cured product obtained from the first composition, X 1 is preferably a divalent group represented by the following formula (1b). *-C(R 3 )(R 4 )-* …(1b) (In formula (1b), R 3 and R 4 are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, or a phenyl group, or R 3 and R 4 are combined with each other to represent an alicyclic structure formed together with the carbon atom to which R 3 and R 4 are attached. "*" represents a bond to the alicyclic oxirane ring structure.)

[0030] In the above formula (1b), the alkyl group and fluoroalkyl group having 1 to 3 carbon atoms represented by R 3 or R 4 may be linear or branched. R 3 and R 4 are combined with each other to represent an alicyclic structure formed together with the carbon atom to which R 3 and R 4 are attached, examples of which include a cyclopentane ring structure, a cyclohexane ring structure, a cycloheptane ring structure, and the like. The alicyclic structure may have a substituent on the ring portion. Examples of the substituent include an alkyl group having 1 to 3 carbon atoms, a halogen atom, and the like.

[0031] In terms of having a higher improvement effect on both the lower dielectric constant and the higher Tg of the cured product of the first composition, R 3 and R 4is each a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group or a phenyl group, or R 3 and R 4 are combined with each other and R 3 and R 4 is preferably an alkyl-substituted or unsubstituted cyclohexane-1,1-diyl group formed together with the carbon atom to which they are attached, more preferably a hydrogen atom, a methyl group, an ethyl group or a trifluoromethyl group, and R 3 and R 4 are more preferably both methyl groups.

[0032] Preferred specific examples of the compound (A1) include compounds represented by the following formula (1-1).

Chemical formula

[0033] In the above formula (1-1), specific examples and preferred examples of R 3 and R 4 are the same as those of R 3 and R 4 in the above formula (1b). R 5 and R 6 Specific examples and preferred examples of are the same as the groups exemplified in the description of R 7 in the above formula (1a). n1 and n2 are preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0034] Further specific examples of the compound (A1) include bis(3,4-epoxycyclohexyl)methane, 1,1-bis(3,4-epoxycyclohexyl)ethane, 1,2-bis(3,4-epoxycyclohexyl)ethane, 2,2-bis(3,4-epoxycyclohexyl)propane, 2,2-bis(3,4-epoxycyclohexyl)hexafluoropropane, 2,2-bis(3,4-epoxycyclohexyl)butane, 1,1-bis(3,4-epoxycyclohexyl)cyclohexane, 1,1-bis(3,4-epoxycyclohexyl)-3,3,5-trimethylcyclohexane and the like.

[0035] Among the above, at least one selected from the group consisting of bis(3,4-epoxycyclohexyl)methane, 1,1-bis(3,4-epoxycyclohexyl)ethane, 1,2-bis(3,4-epoxycyclohexyl)ethane, 2,2-bis(3,4-epoxycyclohexyl)propane, 2,2-bis(3,4-epoxycyclohexyl)hexafluoropropane and 2,2-bis(3,4-epoxycyclohexyl)butane is preferred for the compound (A1), at least one selected from the group consisting of 1,1-bis(3,4-epoxycyclohexyl)ethane, 2,2-bis(3,4-epoxycyclohexyl)propane, 2,2-bis(3,4-epoxycyclohexyl)hexafluoropropane and 2,2-bis(3,4-epoxycyclohexyl)butane is more preferred, and 2,2-bis(3,4-epoxycyclohexyl)propane is particularly preferred.

[0036] In this composition, the content of compound (A1) is preferably 10 to 60% by mass based on the total amount of the polymerizable compounds contained in the composition. When the content of compound (A1) is within the above range, the effects of achieving both a low dielectric constant and a high Tg of the cured product obtained using this composition can be sufficiently enhanced. From the perspective of sufficiently obtaining the improvement effects of low dielectric constant and high Tg of the cured product, the content of compound (A1) is more preferably 15% by mass or more, still more preferably 20% by mass or more, and even more preferably 30% by mass or more based on the total amount of the polymerizable compounds. Also, from the perspective of blending a compound different from compound (A1) as the polymerizable compound to enhance curability and the like, the content of compound (A1) is more preferably 55% by mass or less based on the total amount of the polymerizable compounds.

[0037] · Compound (A2) Compound (A2) is blended into the first composition in order to further improve the curability of the curable composition. Compound (A2) is a polyfunctional polymerizable compound, and any compound not included in the above formula (1) may be used. Examples of compound (A2) include polyfunctional oxirane compounds (excluding compound (A1)), polyfunctional oxetane compounds, polyfunctional vinyl ether compounds, and the like.

[0038] Examples of the polyfunctional oxirane compound include a compound having two or more glycidyl groups per molecule (hereinafter also referred to as "polyfunctional glycidyl compound (a2)"), and a compound having two or more substituted or unsubstituted alicyclic oxiranyl groups per molecule and not included in the above formula (1) (hereinafter also referred to as "polyfunctional alicyclic oxirane compound (a2)").

[0039] Among the polyfunctional oxirane compounds, specific examples of the polyfunctional glycidyl compound (a2) include siloxane compounds having two or more glycidyl groups in the molecule, such as "X-40-2728" (manufactured by Shin-Etsu Chemical Co., Ltd.) under the trade name. Epoxy group-containing resins such as bisphenol A type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol O type epoxy resin, 2,2'-diallylbisphenol A type epoxy resin, hydrogenated bisphenol type epoxy resin, propylene oxide-added bisphenol A type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, sulfide type epoxy resin, diphenyl ether type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, dicyclopentadiene novolac type epoxy resin, biphenyl novolac type epoxy resin, naphthalene phenol novolac type epoxy resin, glycidylamine type epoxy resin, alkyl polyol type epoxy resin, rubber-modified type epoxy resin, glycidyl ester compound, bisphenol A type episulfide resin, etc.; can be mentioned.

[0040] Specific examples of the polyfunctional alicyclic oxirane compound (a2) include 3,4-epoxycyclohexylmethyl 3’,4’-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, etc. Also, as commercially available products, under the trade names, Celoxide 2021P, the same 8010 (both manufactured by Daicel Corporation); KR-470, X-40-2669, X-40-2670, X-40-2678 (all manufactured by Shin-Etsu Chemical Co., Ltd.), etc. can be mentioned.

[0041] The polyfunctional oxetane compound may be a compound having two or more oxetane rings per molecule. Specific examples of the polyfunctional oxetane compound include 3,7-bis(3-oxetanyl)-5-oxa-nonane, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, bis[1-ethyl(3-oxetanyl)]methyl ether, bis(3-ethyl-3-oxetanylmethyl)ether, ethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, triethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, tetraethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, 1,3-bis(3-ethyl-3-oxetanylmethoxy)propane, 1,4-bis(3-ethyl-3-oxetanylmethoxy)butane, 1,4-bis(3-ethyl-3-oxetanylmethoxymethyl)benzene, 1,3-bis(3-ethyl-3-oxetanylmethoxymethyl)benzene, 1,2-bis(3-ethyl-3-oxetanylmethoxymethyl)benzene, 4,4'-bis(3-ethyl-3-oxetanylmethoxymethyl)biphenyl, 2,2'-bis(3-ethyl-3-oxetanylmethoxymethyl)biphenyl, 1,6-bis((3-methyloxetane-3-yl)methoxy)hexane, 1,6-bis((3-ethyloxetane-3-yl)methoxy)hexane, a hydrolysis condensate of 3-[(3-ethyloxetane-3-yl)methoxy]propyltrialkoxysilane, a condensation reaction product of 3-ethyloxetane-3-ylmethanol and a polyscondensate of silanetetraol, compounds represented by each of the following formulas (2a-1) to (2a-3), and the like. [Chemical formula]

[0042] The polyfunctional vinyl ether compound may be a compound having two or more vinyl ether groups per molecule. Specific examples of the polyfunctional vinyl ether compound include compounds having a plurality of vinyl ether groups such as alkanediol divinyl ether, cycloalkanediol divinyl ether, cycloalkanedimethanol divinyl ether, (poly)ethylene glycol divinyl ether, trimethylolpropane divinyl ether, pentaerythritol divinyl ether, trimethylolpropane trivinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol hexavinyl ether, and compounds such as alkylene oxide-modified or caprolactone-modified products thereof.

[0043] The number of polymerizable functional groups contained in one molecule of the compound (A2) is preferably 2 to 10, more preferably 2 to 6, and still more preferably 2 to 4. The molecular weight of the polymerizable compound is preferably 50 to 800, more preferably 70 to 600, and still more preferably 100 to 500 in terms of being easy to adjust to a viscosity suitable for inkjet coating.

[0044] In terms of being able to obtain a curable composition that exhibits excellent curability while achieving a low dielectric constant of the cured product, as the compound (A2), among the above, at least one selected from the group consisting of compounds having a total of two or more oxetane rings in the molecule (i.e., polyfunctional oxetane compounds) and polyfunctional alicyclic oxirane compounds (a2) can be preferably used, and it is more preferable to contain a polyfunctional oxetane compound. The proportion of the polyfunctional oxetane compound is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 65% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more based on the total amount of the compound (A2) contained in the present composition.

[0045] The content of the compound (A2) is preferably 5 to 70% by mass based on the total amount of the polymerizable compounds contained in the present composition from the viewpoint of obtaining a curable composition excellent in curability while achieving a low dielectric constant of the cured product. From the viewpoint of enhancing the curability of the curable composition, the content of the compound (A2) is more preferably 10% by mass or more, and even more preferably 20% by mass or more based on the total amount of the polymerizable compounds contained in the present composition. Further, the content of the compound (A2) is more preferably 67% by mass or less, and even more preferably 65% by mass or less based on the total amount of the polymerizable compounds contained in the present composition from the viewpoint of achieving a high Tg of the cured product.

[0046] In terms of achieving a good balance between a high Tg and a low dielectric constant of the cured film, it is preferable that the content of the compound (A1) is 20% by mass or more based on the total amount of the polymerizable compounds, or the total amount of the compound (A1) and the compound (A2) is 60% by mass or more based on the total amount of the polymerizable compounds. From the viewpoint of making the cured film have a better high Tg and low dielectric constant, it is more preferable that the content of the compound (A1) is 30% by mass or more based on the total amount of the polymerizable compounds, or the total amount of the compound (A1) and the compound (A2) is 70% by mass or more based on the total amount of the polymerizable compounds.

[0047] · Compound (A3) The compound (A3) is a monofunctional polymerizable compound having one oxetanyl group in one molecule (that is, a monofunctional oxetane compound). The monofunctional compound (A3) can be blended into the first composition to improve the wetting spreadability of the curable composition. Further, since the compound (A3) has an oxetanyl group as a polymerizable functional group, it is difficult to remain as an unreacted polymerizable compound in the cured product, and thus the outgas generated from the cured product can be reduced.

[0048] The monofunctional oxetane compound may be a compound having one oxetane ring per molecule. Specific examples of the monofunctional oxetane compound include, for example, 3-ethyl-3-((2-ethylhexyloxy)methyl)oxetane, phenoxymethyloxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(phenoxymethyl)oxetane, 3-ethyl-3-((3-(triethoxysilyl)propoxy)methyl)oxetane, 3-allyloxyoxetane, 3-ethyl-3-allyloxyoxetane, 3-ethyl-3-acryloyloxymethyloxetane, 3-ethyl-3-methacryloyloxymethyloxetane, 2-methyl-2-allyl-4-propyloxetane, 3-ethyl-3-(4-acryloyloxybutyloxy)methyloxetane, 3-ethyl-3-(3-acryloyloxy-2,2-dimethylpropyloxy)methyloxetane, 3-methyl-3-methoxyoxetane, phenyloxetane, 3-ethyl-3-chloromethyloxetane, 3-ethyl-3-oxetanemethanol, 3-amino-3-dimethyloxetane, compounds represented by each of the following formulas (3a-1) to (3a-21), and the like. [Chemical formula]

[0049] From the viewpoint of achieving a low dielectric constant of the cured product while suppressing excessive increase in the viscosity of the curable composition and improving the wetting and spreading properties of the curable composition, the content of the compound (A3) is preferably 20 to 70% by mass based on the total amount of the polymerizable compounds contained in this composition. From the viewpoint of making the wetting and spreading properties of the curable composition more excellent, the content of the compound (A3) is more preferably 30% by mass or more, and even more preferably 35% by mass or more, based on the total amount of the polymerizable compounds contained in this composition. Further, from the viewpoint of obtaining a cured product having sufficiently high mechanical strength and a low dielectric constant, the content of the compound (A3) is more preferably 60% by mass or less, and even more preferably 50% by mass or less, based on the total amount of the polymerizable compounds contained in this composition.

[0050] The total amount of compound (A1), compound (A2), and compound (A3) in the first composition is 85% by mass or more based on the total amount of the polymerizable compounds contained in the first composition. If the total amount of compound (A1), compound (A2), and compound (A3) is less than 85% by mass based on the total amount of the polymerizable compounds contained in the first composition, it tends to be impossible to maintain the balance between the reduction of the dielectric constant and the increase in the glass transition temperature (high Tg) of the cured product obtained from this composition. Also, the amount of outgas generated from the cured product tends to increase. From the viewpoint of obtaining a cured product having a low dielectric constant, a sufficiently high glass transition temperature, and little outgas generation, the total amount of compound (A1), compound (A2), and compound (A3) in the first composition is more preferably 90% by mass or more, still more preferably 95% by mass or more, and even more preferably 98% by mass or more based on the total amount of the polymer compounds contained in the first composition.

[0051] · Other polymerizable compounds The first composition may contain only compound (A1), compound (A2), and compound (A3) as the polymerizable compounds. Also, for the purpose of adjusting the curability and viscosity of this composition, etc., in addition to compound (A1), compound (A2), and compound (A3), a compound different from compound (A1), compound (A2), and compound (A3) (hereinafter, also referred to as "other polymerizable compounds") may be further contained. Examples of other polymerizable compounds include monofunctional oxirane compounds and monofunctional vinyl ether compounds.

[0052] Specific examples of other polymerizable compounds include, as monofunctional oxirane compounds, cyclohexene oxide, 1-methyl-1,2-epoxycyclohexane, 1,2-epoxy-4-vinylcyclohexane, ethyl glycidyl ether, butyl glycidyl ether, 1,2-epoxytetradecane, and the like. Specific examples of monofunctional vinyl ether compounds include cyclohexyl vinyl ether, ethylhexyl vinyl ether, hydroxyethyl vinyl ether, and the like.

[0053] From the viewpoints of sufficiently achieving a low dielectric constant and a high Tg of the cured product and reducing the amount of outgas generated from the cured product, the content of other polymerizable compounds is 15% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 2% by mass or less, based on the total amount of the polymerizable compounds contained in the present composition.

[0054] From the viewpoint of suppressing the amount of outgas generated from the cured product and increasing the glass transition temperature of the cured product, the present composition preferably does not contain a monofunctional oxirane compound in which a monovalent chain group and an oxiranyl group are bonded (for example, ethyl glycidyl ether, butyl glycidyl ether, 1,2-epoxyalkane, etc.), or the content of the monofunctional oxirane compound is as small as possible. Specifically, in the present composition, the content of the monofunctional oxirane compound in which a monovalent chain group and an oxiranyl group are bonded is preferably 0% by mass or more and 10% by mass or less, more preferably 0% by mass or more and 5% by mass or less, still more preferably 0% by mass or more and 1% by mass or less, and even more preferably 0% by mass or more and 0.5% by mass or less, based on the total amount of the present composition.

[0055] The molar ratio of the oxiranyl group to the oxetanyl group in the polymerizable compound is preferably 1:0.5 to 1:8. By setting the molar ratio of the oxiranyl group to the oxetanyl group within the above range, the curing reactivity of the present composition can be made more excellent. In addition, the amount of outgas generated from the cured product can be reduced as much as possible, and a sufficient low dielectric constant of the cured product can be achieved. The molar ratio of the oxiranyl group to the oxetanyl group in the polymerizable compound is more preferably 1:1 to 1:4, and still more preferably 1:1 to 1:3.

[0056] <Polymerization initiator> The polymerization initiator may be any substance that generates a protonic acid or a Lewis acid in response to heat or light. Such a polymerization initiator can be appropriately selected and used from among those known as thermal cationic polymerization initiators or photo cationic polymerization initiators. From the viewpoint of suppressing the deterioration of the device, the polymerization initiator is preferably a photo cationic polymerization initiator among these. Examples of the photo cationic polymerization initiator include ionic photoacid-generating type or non-ionic photoacid-generating type polymerization initiators.

[0057] Examples of the ionic photoacid-generating type photo cationic polymerization initiator include onium salt compounds, halogen-containing compounds, sulfone compounds, sulfonic acid compounds, sulfonimide compounds, and diazomethane compounds. Specifically, as the onium salt compound, the cationic part is an aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, or (2,4-cyclopentadien-1-yl)[(1-methylethyl)benzene]-Fe cation, and the anionic part is BF 4 - , PF 6 - , SbF 6 - , [BX 4 - (X is a phenyl group substituted with two or more fluorine or trifluoromethyl groups.), or [PG 6 - (G is a fluorinated alkyl group). The onium salts composed thereof are mentioned.

[0058] As the polymerization initiator, an onium salt compound among the above can be preferably used. Among them, the polymerization initiator preferably contains an onium fluorinated alkyl fluorophosphate having an anionic part represented by [PF k (C p F 2p+1 ) 6-k - (wherein k is an integer of 3 to 5 and p is an integer of 1 to 3). [PF k (C p F 2p+1 ) 6-k - ​​​The anion part represented by (C p F 2p+1 ) is 1 or more and has a fluorocarbon chain, so it acts as a relatively strong acid. Therefore, the cationic polymerization performance is high, and it is considered that by using such an onium salt, the curability can be made more excellent.

[0059] The cation part of the onium fluorinated alkyl fluorophosphate is not particularly limited. Specific examples of the cation part include, for example, a sulfonium cation represented by the following formula (4).

Chemical formula

[0060] In the above formula (4), R 11 ~R 14 are preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a methoxy group, a methylthio group, a methylcarbonyloxy group, a methylcarbonylthio group, or a methoxycarbonyloxy group, and more preferably a hydrogen atom.

[0061] As the ionic photoacid generator type photo cationic polymerization initiator, commercially available products can be used. For example, as commercially available products of photo cationic polymerization initiators composed of the cation part represented by the above formula (4) and the anion part represented by [PF k (C p F 2p+1 ) 6-k - , there are, by trade name, "CPI-210S", "CPI-410S" (both manufactured by San-Apro Co., Ltd.), etc. Also, as commercially available products of aromatic sulfonium salts, there are, by trade name, "ES-1B", "ES-1S" (both manufactured by San-Apro Co., Ltd.), etc. ​

[0062] Examples of nonionic photoacid-generating photo cationic polymerization initiators include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenol sulfonic acid esters, diazonaphthoquinones, N-hydroxyimide sulfonates, oxime ester-based carboxylic acid esters, and the like.

[0063] In this composition, the content of the polymerization initiator is usually 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the composition. The content of the polymerization initiator is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, with respect to 100 parts by mass of the total amount of the polymerizable compounds. By setting the content of the polymerization initiator within the above range, the curability of the composition can be improved, and a cured film with high transparency can be obtained.

[0064] <Other Components> In addition to the above-described polymerizable compounds and polymerization initiators, this composition may further contain components different from the polymerizable compounds and polymerization initiators (hereinafter also referred to as "other components"). Examples of other components include polymerization inhibitors, antioxidants, sensitizers, surfactants, and the like.

[0065] ·Polymerization Inhibitor / Antioxidant This composition may further contain at least one compound selected from the group consisting of polymerization inhibitors and antioxidants (hereinafter also referred to as "additive (C)"). By further containing additive (C) in this composition, the storage stability of the composition can be improved.

[0066] The polymerization inhibitor is not particularly limited. Examples thereof include hydroquinone, p-methoxyphenol, p-benzoquinone, naphthoquinone, phenanthraquinone, toluquinone, 2,5-diacetoxy-p-benzoquinone, 2,5-dicaproxy-p-benzoquinone, 2,5-acyloxy-p-benzoquinone, 2,5-di-tert-butyl-3-methylphenol, p-tert-butylcatechol, 2,5-di-tert-butylhydroquinone, p-tert-butylcatechol, mono-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, di-tert-butyl·paracresolhydroquinonemonomethylether, phenothiazine, alpha-naphthol, acetamidineacetate, acetamidinesulfate, phenylhydrazinehydrochloride, hydrazinehydrochloride, trimethylbenzylammoniumchloride, laurylpyridiniumchloride, cetyltrimethylammoniumchloride, phenyltrimethylammoniumchloride, trimethylbenzylammoniumoxalate, di(trimethylbenzylammonium)oxalate, trimethylbenzylammoniummalate, trimethylbenzylammoniumtartrate, trimethylbenzylammoniumglycolate, phenyl-β-naphthylamine, parabenzylaminophenol, di-β-naphthylparaphenylenediamine, dinitrobenzene, trinitrotoluene, picric acid, cyclohexanoneoxime, pyrogallol, tannic acid, resorcin, triethylaminehydrochloride, dimethylanilinehydrochloride, dibutylaminehydrochloride, and the like.

[0067] When the additive (C) is blended in the present composition, the content of the additive (C) is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and still more preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the present composition. By setting it within the above range, while suppressing an increase in viscosity due to unnecessary thermal energy, gelation or a curing reaction from occurring, the viscosity of the present composition can be maintained within an appropriate range even after long-term circulation or storage, and good wet spreadability (and thus inkjet coatability) can be ensured.

[0068] ·Antioxidant The antioxidant is used to improve the storage stability of the curable composition by preventing oxidative degradation thereof. Examples of the antioxidant include phenolic antioxidants, sulfur antioxidants, phosphorus antioxidants and the like.

[0069] Specific examples of the antioxidant include, as phenolic antioxidants, monophenols such as 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-p-ethylphenol and stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; bisphenols such as 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol) and 3,9-bis[1,1-dimethyl-2-{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane; polymeric phenols such as 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-tert-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione and tocopherol;

[0070] Examples of sulfur-based antioxidants include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, and the like. Examples of phosphorus-based antioxidants include phosphites such as diphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetrayl bis(octadecyl) phosphite, cyclic neopentanetetrayl bis(2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetrayl bis(2,4-di-tert-butyl-6-methylphenyl) phosphite, and bis[2-tert-butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl] hydrogen phosphite; oxaphosphaphenanthrene oxides such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0071] The antioxidants may be used alone, but it is particularly preferred to use them in combination with phenolic / sulfur-based or phenolic / phosphorus-based. Also, commercially available phenolic antioxidants (for example, IRGANOX 1010 (trade name) manufactured by BASF Japan Ltd.) and commercially available phosphorus-based antioxidants (for example, IRGAFOS 168 (trade name) manufactured by BASF Japan Ltd.) may be used alone, or they may be mixed and used.

[0072] When an antioxidant is blended in the composition, the content of the antioxidant is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and still more preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the composition. By setting it within the above range, while suppressing the viscosity increase due to unnecessary thermal energy and the occurrence of gelation or curing reaction, the viscosity of the composition can be maintained within an appropriate range even after long-term circulation or storage, and good wet spreading property (and thus inkjet coating property) can be ensured.

[0073] In addition, in order to enhance the storage stability of the composition, in addition to the above-mentioned additive (C), a heat stabilizer such as methylenequinone or 2-dimethylaminomethanol described in JP-T-2020-518952 may be contained in the composition.

[0074] · Sensitizer The sensitizer is used for the purpose of reducing the amount of polymerization initiator used as much as possible, thereby enhancing the transparency of the cured product. Specific examples of the sensitizer include polynuclear aromatics such as pyrene, perylene, triphenylene, anthracene, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 3,7-dimethoxyanthracene, 9,10-dipropyloxyanthracene; xanthenes such as fluorescein, eosin, erythrosine, rhodamine B, rose bengal; xanthones such as xanthone, thioxanthone, dimethylthioxanthone, diethylthioxanthone (such as 2,4-diethylthioxanthen-9-one), isopropylthioxanthone (such as 2-isopropylthioxanthone); cyanines such as thiacarbocyanine, oxacarbocyanine; merocyanines such as merocyanine, carbomerocyanine; thiazines such as thionin, methylene blue, toluidine blue; acridines such as acridine orange, chloroflavin, acriflavin; acridones such as acridone, 10-butyl-2-chloroacridone; base styryls such as 2-[2-[4-(dimethylamino)phenyl]ethenyl]benzoxazole; coumarins such as 7-diethylamino-4-methylcoumarin, 7-hydroxy-4-methylcoumarin, 2,3,6,7-tetrahydro-9-methyl-1H,5H,11H[l]benzopyrano[6,7,8-ij]quinolizin-11-one; rhodacyanines; oxonols; anthraquinones; squariliums; styryls; and the like.

[0075] When the sensitizer is blended in the composition, the content of the sensitizer is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and still more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the composition. By setting it within the above range, the transparency of the cured product can be further enhanced.

[0076] ·Surfactant Surfactants can be used to improve the coatability of the present composition (specifically, wet spreading property and reduction of coating unevenness) and the surface flatness of the cured product. Examples of surfactants include fluorosurfactants, silicone surfactants, and nonionic surfactants.

[0077] Specific examples of surfactants include, as fluorosurfactants, the following trade names: Megafac F-171, F-172, F-173, F-251, F-430, F-554, F-556, F-557, F-559, F-560, F-563 (all manufactured by DIC Corporation); Fluorad FC430, FC431 (both manufactured by Sumitomo 3M Limited); Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106, S-611 (all manufactured by AGC Seimi Chemical Co., Ltd.); Polyflow No.75, No.95 (both manufactured by Kyoeisha Chemical Co., Ltd.); FTX-218 (manufactured by Neos Co., Ltd.); EFtop EF301, EF303, EF352 (all manufactured by Shin-Akita Chemical Co., Ltd.), and the like.

[0078] Specific examples of silicone surfactants include, under the following trade names: SH200-100cs, SH28PA, SH30PA, SH89PA, SH190, SH8400, SH193, SZ6032, SF8428, DC57, DC190, PaintAD19, FZ-2101, FZ-77, FZ-2118, L-7001, L-7002 (all manufactured by Toray Dow Corning Co., Ltd.); Organosiloxane Polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.); BYK-300, 306, 310, 330, 333, 335, 341, 344, 370, 340, 345 (all manufactured by BYK-Chemie Japan Co., Ltd.).

[0079] Examples of nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, and the like.

[0080] When a surfactant is blended in the present composition, the content of the surfactant is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 3 parts by mass, and still more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the present composition.

[0081] Examples of other components include softeners, plasticizers, adhesion aids, organic solvents, etc. in addition to the above. The blending ratios of these components are appropriately selected according to each component within a range that does not impair the effects of the present disclosure.

[0082] An organic solvent may be blended in the present composition for the purpose of dissolving each component to be blended therein. On the other hand, from the viewpoint of enabling the formation of a cured film (particularly, an organic encapsulation layer that protects the organic light-emitting layer of an organic EL element) without performing heat treatment, it is preferable to minimize the amount of the organic solvent used. Specifically, the content of the organic solvent in the present composition is preferably 0% by mass or more and 3% by mass or less, more preferably 0% by mass or more and 2% by mass or less, still more preferably 0% by mass or more and 1% by mass or less, and even more preferably 0% by mass or more and 0.5% by mass or less.

[0083] When the present composition contains an organic solvent, an organic solvent that can dissolve or disperse each component blended in the present composition and does not react with each component can be preferably used. Specifically, alcohols, ketones, esters, ethers, aromatic hydrocarbons, and amides can be mentioned.

[0084] Examples of these include, as alcohols, methanol, ethanol, isopropanol, butanol, octanol and the like. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like. Examples of esters include ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate and the like. Examples of ethers include polyoxyethylene lauryl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol methyl ethyl ether and the like. Examples of aromatic hydrocarbons include benzene, toluene, xylene and the like. Examples of amides include amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone and the like.

[0085] The composition of the second embodiment in the present composition (hereinafter, also referred to as "the second composition") contains the following compound (A1), compound (A2) and compound (B3) as polymerizable compounds. · Compound (A1): A compound represented by the following formula (1) R 1 -X 1 -R 2 …(1) (In formula (1), R 1 and R 2 are each independently a substituted or unsubstituted alicyclic oxiranyl group. X 1 is a divalent hydrocarbon group or a halogenated hydrocarbon group.) · Compound (A2): A polyfunctional polymerizable compound (excluding compound (A1)). · Compound (B3): A monofunctional polymerizable compound Regarding the second composition, hereinafter, the description will focus on the differences from the first composition.

[0086] For the specific examples, preferred examples, and content of Compound (A1) and Compound (A2) contained in the second composition, since they are the same as the description of the compounds exemplified as Compound (A1) and Compound (A2) contained in the first composition, the description thereof is omitted.

[0087] As the compound (B3) contained in the second composition, there is no particular limitation as long as the dielectric constant of the cured product obtained by curing the second composition is 2.70 or less at 25 °C and a frequency of 250 kHz, and the glass transition temperature of the cured product is 85 °C or higher. From the viewpoint of minimizing the generation of outgas from the cured product, as the compound (B3), a monofunctional polymerizable compound having one oxetanyl group in one molecule (that is, a monofunctional oxetane compound) can be preferably used. The proportion of the monofunctional oxetane compound is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more based on the total amount of the compound (B3) contained in the second composition.

[0088] The content of the compound (B3) is preferably 30 to 70% by mass based on the total amount of the polymerizable compounds contained in this composition from the viewpoints of achieving a low dielectric constant of the cured product while suppressing the viscosity of the curable composition from becoming too high and improving the wetting spreadability of the curable composition. From the viewpoint of making the wetting spreadability of the curable composition more excellent, the content of the compound (B3) is more preferably 35% by mass or more based on the total amount of the polymerizable compounds contained in this composition. Further, the content of the compound (B3) is more preferably 60% by mass or less, and still more preferably 50% by mass or less based on the total amount of the polymerizable compounds contained in this composition from the viewpoints of obtaining a cured product with sufficiently high mechanical strength and a low dielectric constant.

[0089] The second composition may contain only Compound (A1), Compound (A2), and Compound (B3) as the polymerizable compounds. Further, for the purpose of adjusting the curability and viscosity of this composition, etc., the second composition may further contain a compound different from Compound (A1), Compound (A2), and Compound (B3) together with Compound (A1), Compound (A2), and Compound (B3).

[0090] Details of the polymerization initiator contained in the second composition and the components optionally contained in the second composition are the same as those of the first composition, and thus the description thereof is omitted.

[0091] <Preparation of curable composition> This composition can be prepared by mixing a polymerizable compound, a polymerization initiator, and other components optionally blended. From the viewpoints of obtaining a curable composition with good sensitivity and forming a cured film with a high sealing effect, the content of the polymerizable compound in this composition is preferably 80 parts by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more with respect to 100 parts by mass of the total amount of this composition.

[0092] <Viscosity of curable composition> This composition preferably has a viscosity measured under the conditions of 25°C and 20 rpm using an E-type viscometer in the range of 1.0 to 40.0 mPa·s. When the viscosity of this composition is 40.0 mPa·s or less, the wetting and spreading properties are good when this composition is applied onto a substrate by inkjet coating, and coating unevenness due to repelling or the like can be sufficiently suppressed. Also, when the viscosity of this composition is 1.0 mPa·s or more, a sufficient film thickness can be ensured when this composition is applied onto a substrate, and an organic sealing layer that sufficiently exhibits the sealing effect can be formed. This composition is suitable as a curable composition for inkjet coating.

[0093] From the viewpoint of obtaining a curable composition having excellent inkjet coatability, the viscosity of this composition is more preferably 35.0 mPa·s or less, still more preferably 30.0 mPa·s or less, and particularly preferably 25.0 mPa·s or less. Also, from the viewpoints of stably performing ejection by inkjet and ensuring a sufficient film thickness, the viscosity of this composition is more preferably 2.0 mPa·s or more, and still more preferably 5.0 mPa·s or more. In this specification, the viscosity of the curable composition is a value measured in accordance with JIS K2283.

[0094] "Hardened Product and Organic EL Element" The hardened product of the present disclosure (hereinafter also referred to as "this hardened product") is formed by the curable composition prepared as described above. According to this composition, a hardened product with a low dielectric constant, a high glass transition temperature, and little outgassing can be obtained. Such a composition can be used, for example, as various materials for the encapsulation structure of organic EL elements, microlenses, antireflection films, diffraction gratings of AR elements, etc. In addition, this composition can also be used as a material for forming hole fillers for holes such as the HID (Hole In a Display area) structure and planarization films. Furthermore, according to this composition, since it has low water permeability, can prevent the intrusion of foreign substances, and can form a hardened film with excellent bending resistance, it can also be used as a material for forming a coating layer for protecting wiring at the bent portion of a flexible display or at the bend allowance portion where wiring extending from the display portion to the outside is provided. Examples of the coating layer for the bent portion include the microcoating layer (MICRO-COATING LAYER) described in International Publication No. 2016 / 09925. The microcoating layer can be formed by slit coating or by inkjet coating. This composition is useful in that it can be compatible with any of these coating methods. This composition is particularly useful as a composition for forming an encapsulation structure for performing thin film encapsulation (TFE: Thin Film Encapsulation) on an organic electroluminescence element (organic EL element), thereby forming an encapsulation structure, that is, an encapsulant for organic EL elements.

[0095] <Dielectric Constant of Hardened Product> The cured product preferably has a dielectric constant of 2.70 or less at 25°C and a frequency of 250 kHz. When the dielectric constant under the said measurement conditions is 2.70 or less, when forming a low dielectric constant layer of a device adopting a touch panel method (for example, an organic EL light emitting device) with a curable composition, the dielectric constant of the low dielectric constant layer can be made sufficiently low, and it is possible to suppress malfunction during the use of the touch panel. From the viewpoint of forming a low dielectric constant layer exhibiting desired performance, the dielectric constant of the cured product at 25°C and a frequency of 250 kHz is more preferably 2.69 or less, and even more preferably 2.68 or less. There is no particular limitation on the lower limit of the dielectric constant of the cured product. The dielectric constant of the cured product at 25°C and a frequency of 250 kHz is, for example, 2.0 or more.

[0096] Regarding the detailed method for measuring the dielectric constant, a UV-LED lamp with a wavelength of 395 nm is used, and the illuminance is 1,000 mW / cm 2 and the integrated light quantity is 1,000 mJ / cm 2 The value is measured under the conditions of 25°C and a frequency of 250 kHz for the cured product obtained by irradiating the present composition with ultraviolet rays under the conditions. The details of the method for measuring the dielectric constant follow the method described in the examples described later.

[0097] <Glass transition temperature of the cured product> It is preferable that the cured product has a glass transition temperature (Tg) of 85°C or higher. When the glass transition temperature of the cured product is 85°C or higher, it is possible to suppress the occurrence of strain in the lower layer when forming another layer (upper layer) on the layer (lower layer) formed by the curable composition, thereby suppressing the occurrence of cracks. From the viewpoint of suppressing the generation of strain in the cured product formed by the curable composition, the glass transition temperature of the cured product formed by this composition is more preferably 90°C or higher, still more preferably 95°C or higher, even more preferably 98°C or higher, and particularly preferably 100°C or higher. There is no particular limitation on the upper limit of the glass transition temperature of the cured product formed by this composition. The glass transition temperature of the cured product formed by this composition is, for example, 200°C or lower. The glass transition temperature of the cured product is a value determined by dynamic viscoelasticity measurement. Details of the method for measuring the glass transition temperature of the cured product follow the method described in the examples below.

[0098] <Outgassing amount of the cured product> When components of the curable composition (specifically, unreacted polymerizable compounds, solvents, etc.) remain in the cured product formed by the curable composition, outgassing may easily occur from the cured product due to decomposition products of unreacted polymerizable compounds and the like. On the other hand, outgassing generated from the cured product may cause deterioration of the device, so it is required to be as little as possible. In this regard, according to this composition, a cured product with a small outgassing amount can be obtained. Specifically, it is preferable that the outgassing amount generated from the cured film with a thickness of 8 μm formed by this composition is 800 ppm or less when heated at 110°C for 30 minutes. The outgassing amount generated from the cured film is a value measured by gas chromatography using the headspace method. Details of the method for measuring the outgassing amount from the cured film follow the method described in the examples below.

[0099] 《Method for manufacturing an organic EL device》 This cured product and the organic EL device in which the organic light-emitting layer is sealed with this cured product can be manufactured by a method including the following steps 1 and 2 using this composition. (Step 1) A step of applying the present composition to the light-emitting layer formation surface of a substrate on which an organic light-emitting layer is formed (Step 2) A step of forming a sealing structure (organic sealing layer) by irradiating radiation to cure the present composition Hereinafter, each step will be described in detail.

[0100] [Step 1: Coating Step] In this step, by applying the present composition to the light-emitting layer formation surface of a substrate on which an organic light-emitting layer is formed, a coating film made of the present composition is formed on the light-emitting layer formation surface. The substrate to which the present composition is applied has, in addition to the organic light-emitting layer, a laminate provided with various layers such as an anode layer, a hole injection layer, a hole transport layer, an electron injection layer, and a cathode layer, and an organic EL element is constituted by this laminate. The light-emitting layer formation surface to which the present composition is applied may be covered with an inorganic film (inorganic sealing layer). Examples of the inorganic material constituting the inorganic film include silicon nitride (SiNx) and silicon oxide (SiOx). In this case, a thin film sealing layer including an organic sealing layer and an inorganic sealing layer is formed as a sealing structure on the organic light-emitting layer.

[0101] Examples of the method of applying the present composition include a spray method, a roll coating method, a spin coating method, a slit die coating method, a bar coating method, and an inkjet coating method. From the viewpoints of throughput and thinning of the film, among these, the inkjet coating method can be preferably applied. Since the present composition has excellent curability while having a low viscosity and the occurrence of coating unevenness is suppressed, it can be suitably used for inkjet coating.

[0102] [Step 2: Curing Step] In this step, a cured film is obtained by irradiating the coating film formed in the above Step 1 with radiation to cure the coating film. Examples of the radiation include charged particle beams such as ultraviolet rays, far ultraviolet rays, visible light rays, X-rays, and electron beams. Among these, ultraviolet rays are preferable, and for example, ultraviolet rays having a wavelength of 350 to 400 nm can be preferably used as the irradiation light. The exposure amount of the radiation is 0.05 to 10 J / m 2is preferable. Thus, an organic EL element coated with the organic encapsulation layer made of this composition can be obtained. The thickness of the cured film is usually 0.5 to 15 μm.

[0103] The organic encapsulation layer formed by this composition may be further coated with an inorganic film (inorganic encapsulation layer). Examples of the inorganic material constituting the inorganic film include silicon nitride (SiNx), silicon oxide (SiOx), and the like. When a thin film encapsulation layer including an organic encapsulation layer and an inorganic encapsulation layer is provided on the organic EL element, by forming the organic encapsulation layer with this composition, the organic encapsulation layer can be made moderately hard. Thereby, even when an inorganic encapsulation layer is further formed on the surface of the organic encapsulation layer, it is possible to suppress the occurrence of cracks in the organic encapsulation layer.

[0104] The organic EL element of the present disclosure manufactured by the method including the above-described Step 1 and Step 2 includes an organic light-emitting layer and an organic encapsulation layer made of this composition, and the organic light-emitting layer is encapsulated by the organic encapsulation layer. Therefore, in the organic EL element of the present disclosure, the intrusion of moisture into the organic light-emitting layer can be sufficiently suppressed, so that inconveniences caused by moisture, specifically, the occurrence of dark spots and the deterioration of light-emitting characteristics such as luminance and luminous efficiency can be suppressed. Further, in the organic EL element of the present disclosure, the generation of outgas from the organic encapsulation layer is small, and the dielectric constant of the organic encapsulation layer is sufficiently low. Such an organic EL element of the present disclosure is useful, for example, as an organic EL lighting device or an organic EL display device.

[0105] According to the present disclosure described in detail above, the following means are provided. 〔Means 1〕 A curable composition containing a polymerizable compound and a polymerization initiator, wherein the polymerizable compound includes a compound (A1) represented by the above formula (1), a compound (A2) which is a polyfunctional polymerizable compound (excluding the compound (A1)), and a compound (A3) which is a monofunctional polymerizable compound having one oxetanyl group in one molecule, and the total amount of the compound (A1), the compound (A2), and the compound (A3) is 85% by mass or more based on the total amount of the polymerizable compound. [Means 2] The curable composition of [Means 1], containing 10 to 60% by mass of the compound (A1), 5 to 70% by mass of the compound (A2), and 20 to 70% by mass of the compound (A3) with respect to the total amount of the polymerizable compounds. [Means 3] The curable composition of [Means 1], wherein the molar ratio of the oxiranyl group to the oxetanyl group in the polymerizable compound is 1:0.5 to 1:8. [Means 4] The curable composition according to any one of [Means 1] to [Means 3], wherein the proportion of the polyfunctional oxetane compound in the compound (A2) is 30% by mass or more. [Means 5] The curable composition according to any one of [Means 1] to [Means 4], wherein the compound (A1) is represented by the above formula (1-1). [Means 6] R in the above formula (1-1) 3 and R 4 are methyl groups, and the curable composition of [Means 5]. [Means 7] The curable composition according to any one of [Means 1] to [Means 6], wherein the content of the monofunctional oxirane compound formed by bonding a monovalent chain group and an oxiranyl group is 10% by mass or less of the whole composition. [Means 8] The curable composition according to any one of [Means 1] to [Means 7], wherein the dielectric constant of the cured product of the curable composition at 25 °C and a frequency of 250 kHz is 2.70 or less. [Means 9] The curable composition according to any one of [Means 1] to [Means 8], wherein the glass transition temperature of the cured product of the curable composition is 85 °C or higher. [Means 10] The curable composition according to any one of [Means 1] to [Means 9], which is for inkjet coating. [Means 11] The curable composition according to any one of [Means 1] to [Means 10], which is for forming a sealing structure for sealing the organic light-emitting layer of an organic EL element. 〔Means 12〕A curable composition containing a polymerizable compound and a polymerization initiator, wherein the polymerizable compound includes a compound represented by the above formula (1), a polyfunctional polymerizable compound (excluding the compound (A)), and a monofunctional polymerizable compound, and the dielectric constant of the cured product of the curable composition at 25 °C and a frequency of 250 kHz is 2.70 or less, and the glass transition temperature of the cured product is 85 °C or higher. 〔Means 13〕A cured film formed using the curable composition according to any one of 〔Means 1〕 to 〔Means 12〕. 〔Means 14〕An organic EL element including an organic light-emitting layer and an organic encapsulation layer for encapsulating the organic light-emitting layer, wherein the organic encapsulation layer is formed using the curable composition according to any one of 〔Means 1〕 to 〔Means 12〕. 〔Means 15〕A method for manufacturing an organic EL element including an organic light-emitting layer and an organic encapsulation layer for encapsulating the organic light-emitting layer, the method including: a step of applying the curable composition according to any one of 〔Means 1〕 to 〔Means 12〕 to the light-emitting layer formation surface of a substrate on which the organic light-emitting layer is formed; and a step of forming the organic encapsulation layer by irradiating radiation to cure the curable composition. 〔Means 16〕The method for manufacturing an organic EL element according to 〔Means 15〕, wherein the curable composition is applied by inkjet coating.

Examples

[0106] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0107] 1. Preparation of curable composition The components used for preparing the curable composition are as follows. 〈Polymerizable compound〉 · Polyfunctional compound A1-1: The compound described in

[0106] formula (5) of Korean Patent Publication No. 10-2022-0160362 A2-1: OXT-221 (3,3′-(oxybis(methylene))bis(3-ethyloxetane), manufactured by Toagosei Co., Ltd.) A2-2: Celloxide 2021P (manufactured by Daicel Corporation) A2-3: Celloxide 8010 (manufactured by Daicel Corporation) A2-4: KR-470 (manufactured by Shin-Etsu Chemical Co., Ltd.) A2-5: X-40-2669 (manufactured by Shin-Etsu Chemical Co., Ltd.) A2-6: X-40-2678 (manufactured by Shin-Etsu Chemical Co., Ltd.) · Monofunctional compound A3-1: ОXT-212 (3-ethyl-3-((2-ethylhexyloxy)methyl)oxetane, manufactured by Toagosei Co., Ltd.) A3-2: 1,2-epoxytetradecane (manufactured by Yokkaichi Gosei Co., Ltd.) 〈Polymerization initiator〉 B-1: Photo cationic polymerization initiator (CPI-210S manufactured by San-Apro Ltd.) 〈Sensitizer〉 C-1: 9,10-dibutoxyanthracene 〈Surfactant〉 D-1: Silicon-containing nonionic surfactant (BYK-333 manufactured by BYK-Chemie Japan)

[0108] [Example 1] In an air atmosphere, 50 parts by mass of compound (A1-1), 10 parts by mass of compound (A2-1), 40 parts by mass of compound (A3-1), 3 parts by mass of polymerization initiator (B-1), 1 part by mass of sensitizer (C-1), and 1 part by mass of surfactant (D-1) were mixed to prepare a curable composition.

[0109] [Examples 2 to 6 and Comparative Examples 1 to 6] A curable composition was prepared in the same manner as in Example 1, except that the types and amounts of the polymerizable compounds were changed as shown in Table 1. In Table 1, the numerical values in the column of "oxetanyl group / oxiranyl group [mol / mol]" represent the molar ratio of the oxiranyl group and the oxetanyl group in the polymerizable compounds used in the preparation of each curable composition. The molar ratio was determined from the blending composition of the polymerizable compounds.

[0110] 2. Evaluation For the curable compositions of Examples 1 to 6 and Comparative Examples 1 to 6, the following items were evaluated by the methods described below. The evaluation results are shown in Table 1.

[0111] <Dielectric Constant of the Cured Film> On a substrate with ITO vapor-deposited on a non-alkali glass with a thickness of 30 nm, the curable composition was applied using a spin coater so that the thickness after curing would be 8 μm. Next, ultraviolet light with a wavelength of 395 nm was irradiated using an LED UV lamp at an illuminance of 1000 mW / cm 2 and an integrated light quantity of 1,000 mJ / cm 2 to cure the curable composition and form a cured film. As the LED UV lamp, UniJet E110Z HD (Type U395A-455, manufactured by Ushio Inc.) was used. Thereafter, aluminum was vapor-deposited on the surface of the cured film with a thickness of 50 nm to prepare a test piece for dielectric constant measurement. For the obtained test piece, the dielectric constant was measured at 25°C and 250 kHz using a dielectric constant measuring device. As the dielectric constant measuring device, a 4284A type LCR meter (manufactured by HEWLETT PACKARD) was used.

[0112] <Glass Transition Temperature (Tg) of the Cured Film> The curable composition was spin-coated on a 95 mm square glass substrate subjected to a release treatment. Subsequently, ultraviolet light with a wavelength of 395 nm was irradiated under nitrogen using an LED lamp to cure the curable composition and form a cured film. The cured film formed on the glass substrate was peeled off from the substrate to obtain a cured film with a thickness of 60 μm. For the obtained cured film, the glass transition temperature of the cured film was measured by measuring the peak top of Tanδ using a dynamic viscoelasticity measuring device ("DVA-225" manufactured by IT Measurement & Control Co., Ltd.).

[0113] <Outgassing Amount> The amount of gas (outgas) generated when the cured film of the curable composition was heated was measured by gas chromatography using the headspace method. The measurement was carried out according to the following procedure. First, the curable composition was applied to a thickness of 8 μm using a spin coater. Next, after irradiating with ultraviolet light having a wavelength of 395 nm at an illuminance of 1,000 mW / cm 2 and an integrated light quantity of 1,000 mJ / cm 2 under the conditions of irradiation and curing, the cured film was placed in a headspace vial, the vial was sealed, and heated at 110 °C for 30 minutes, and the outgas amount was measured by the headspace method. ○: The outgas amount is 300 ppm or more and less than 800 ppm ×: The outgas amount is 800 ppm or more

[0114]

Table 1

[0115] As shown in Table 1, the cured films formed from the curable compositions of Examples 1 to 6 had a high glass transition temperature of 85 °C or higher, a dielectric constant lower than 2.70, and moreover, a small amount of outgas generation. Among these, the cured film formed from the curable composition containing 20% by mass or more of the compound (A1-1) based on the total amount of the polymerizable compounds had a high glass transition temperature of 100 °C or higher and a dielectric constant lower than 2.65, and it was possible to sufficiently achieve an increase in the Tg and a decrease in the dielectric constant of the cured film (Examples 1 to 4). Also, for the cured film formed from the curable composition containing 70% by mass or more of the total amount of the compound (A1) and the compound (A2) based on the total amount of the polymerizable compounds, the glass transition temperature was as high as 100 °C or higher and the dielectric constant was as low as 2.65, and it was possible to sufficiently achieve an increase in the Tg and a decrease in the dielectric constant of the cured film (Example 6).

[0116] On the other hand, the cured films formed from the curable compositions of Comparative Examples 1 and 2 had a sufficiently high glass transition temperature, but the dielectric constant was higher than 2.70. Also, the cured film formed from the curable composition of Comparative Example 3 had a low glass transition temperature of 55°C, and the dielectric constant was also as high as 2.72. The cured films formed from the curable compositions of Comparative Examples 4 to 6 had a dielectric constant lower than 2.70, while the glass transition temperature was lower than 80°C. Regarding Comparative Example 6, the outgas generation amount of the cured film was also large.

Claims

1. A curable composition containing a polymerizable compound and a polymerization initiator, wherein the polymerizable compound comprises a compound (A1) represented by the following formula (1): R １ -X １ -R ２ …(1) (In formula (1), R １ and R ２ are, independently of each other, a substituted or unsubstituted alicyclic oxiranyl group. X １ is a divalent hydrocarbon group or a halogenated hydrocarbon group.) a compound (A2) which is a polyfunctional polymerizable compound (excluding the compound (A1)), and a compound (A3) which is a monofunctional polymerizable compound having one oxetanyl group in one molecule, and the total amount of the compound (A1), the compound (A2), and the compound (A3) is 85% by mass or more based on the total amount of the polymerizable compound. A curable composition.

2. The curable composition according to claim 1, containing 10 to 60% by mass of the compound (A1), 5 to 70% by mass of the compound (A2), and 20 to 70% by mass of the compound (A3) based on the total amount of the polymerizable compound.

3. The curable composition according to claim 1, wherein the molar ratio of the oxiranyl group to the oxetanyl group in the polymerizable compound is 1:0.5 to 1:

8.

4. The curable composition according to claim 1, wherein the proportion of the polyfunctional oxetane compound in the compound (A2) is 30% by mass or more.

5. The curable composition according to claim 1, wherein the compound (A1) is represented by the following formula (1-1). 【Chemical 1】 (In formula (1-1), R ３ and R ４ are, independently of each other, a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms or a phenyl group, or R ３ and R ４ are combined with each other to represent an alicyclic structure formed together with the carbon atom to which R ３ and R ４ are attached. R ５ and R ６ are, independently of each other, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms. n1 and n2 are, independently of each other, an integer of 0 to 3.)

6. R in the above formula (1-1) ３ and R ４ The curable composition according to claim 5, wherein is a methyl group.

7. The curable composition according to claim 1, wherein the content of the monofunctional oxirane compound formed by bonding a monovalent chain group and an oxiranyl group is 10% by mass or less of the whole composition.

8. The curable composition according to claim 1, wherein the dielectric constant of the cured product of the curable composition at 25°C and a frequency of 250 kHz is 2.70 or less.

9. The curable composition according to claim 1, wherein the glass transition temperature of the cured product of the curable composition is 85°C or higher.

10. The curable composition according to claim 1, which is for inkjet coating.

11. The curable composition according to claim 1, which is for forming a sealing structure for sealing an organic light-emitting layer of an organic EL element.

12. A curable composition containing a polymerizable compound and a polymerization initiator, wherein the polymerizable compound comprises a compound represented by the following formula (1): R １ -X １ -R ２ …(1) (In formula (1), R １ and R ２ are each independently a substituted or unsubstituted alicyclic oxiranyl group. X １ is a divalent hydrocarbon group or a halogenated hydrocarbon group.) a compound, and a polyfunctional polymerizable compound (excluding the compound (A1)), and a monofunctional polymerizable compound, and the dielectric constant of the cured product of the curable composition at 25°C and a frequency of 250 kHz is 2.70 or less, and the glass transition temperature of the cured product is 85°C or higher. A curable composition.

13. A cured film formed using the curable composition according to any one of claims 1 to 12.

14. An organic light-emitting layer, An organic encapsulation layer that encapsulates the organic light-emitting layer, Comprising: An organic EL element in which the organic encapsulation layer is formed using the curable composition according to any one of claims 1 to 12.

15. A method for manufacturing an organic EL element comprising an organic light-emitting layer and an organic encapsulation layer that encapsulates the organic light-emitting layer, A step of applying the curable composition according to any one of claims 1 to 12 to the light-emitting layer formation surface of a substrate on which the organic light-emitting layer is formed; A step of forming the organic encapsulation layer by irradiating radiation to cure the curable composition; A method for manufacturing an organic EL element, including:

16. The method for manufacturing an organic EL element according to claim 15, wherein the curable composition is applied by inkjet coating.

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