Curable composition for encapsulant of organic EL display element, cured film, organic EL display element, and method for manufacturing the same.

Abstract

To provide a curable composition for organic EL display element encapsulants, a cured film, an organic EL display device, and a method for manufacturing the same, which have low viscosity, reduce the generation of moisture from the cured film, and suppress the degradation of organic EL display elements. [Solution] A curable composition for organic EL display element encapsulant, comprising a polymerizable compound and a cationic polymerization initiator, wherein the polymerizable compound contains a compound having at least one group selected from an oxetanyl group and an oxyranyl group, the viscosity at 25°C is 3.0 mPa·s or more and 25.0 mPa·s or less, and the amount of water generated from the cured film detected when the cured film of the curable composition is heated from 25°C to 200°C using TPD-MS is 1800 ppm by mass or less relative to the mass of the cured film.

Description

[Technical Field]

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

[0002] Organic electroluminescent (OLED) display elements are light-emitting devices having a multilayer structure including an anode, an organic light-emitting layer, and a cathode. OLED display elements are widely used in various applications such as display devices and lighting equipment.

[0003] The organic light-emitting layer of an organic EL display element is susceptible to degradation due to contact with moisture and oxygen. For example, prolonged operation may cause moisture to penetrate the element, leading to the formation of areas that do not emit light (hereinafter also referred to as "dark spots"), or the light-emitting properties may deteriorate due to contact with moisture and oxygen. Therefore, conventional organic EL display elements have been provided with a sealing structure to enclose the organic light-emitting layer, preventing it from coming into contact with moisture and oxygen (see, for example, Patent Document 1).

[0004] Patent Document 1 discloses a method for forming a sealing material with excellent moisture resistance by using a sealing material that includes a polymerizable compound containing a compound with a specific gravity of 1.3 to 4.0 and a polymerization initiator having elements from groups 13 to 15 of the periodic table and periods 4 to 6. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2022 / 085599 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the present inventors have found that even with organic EL display elements formed with a moisture-resistant encapsulant as described in Patent Document 1, degradation of the organic EL display element, such as the formation of dark spots, can still occur. This is thought to be because the organic EL display element is degraded by moisture and low-boiling point components generated when the encapsulant decomposes due to residual components in the encapsulant. Furthermore, the sealing material described in Patent Document 1 has high viscosity, making it difficult to apply using the inkjet method.

[0007] The present invention has been made in view of the above problems, and its main objective is to provide a curable composition for an organic EL display element encapsulant that provides an organic EL display element with excellent inkjet coating properties, reduced malfunctions, and suppressed degradation, resulting in an organic EL display element with excellent element reliability. [Means for solving the problem]

[0008] According to the present invention, the following curable composition for encapsulating organic EL display elements, a cured film, an organic EL display element, and a method for manufacturing the same are provided.

[0009] [1] comprising a polymerizable compound and a cationic polymerization initiator, The polymerizable compound contains a compound having at least one group selected from an oxetanyl group and an oxyranyl group, The viscosity at 25°C is between 3.0 mPa·s and 25.0 mPa·s. The amount of water generated from the cured film of a curable composition when heated from 25°C to 200°C using TPD-MS is 1800 ppm by mass or less relative to the mass of the cured film. A curable composition for encapsulating organic EL display elements. [2] A cured film formed using the curable composition for organic EL display element encapsulant described in [1] above. [3] An organic EL display element in which the organic light-emitting layer is sealed with the cured film described in [2] above. [4] A method for manufacturing an organic EL display element, comprising the following steps 1 and 2. (Step 1) A step of applying the curable composition for organic EL display element encapsulant [1] to the organic light-emitting layer forming surface of a substrate on which an organic light-emitting layer has been formed. (Step 2) A step of forming a sealing structure by curing the curable composition for the organic EL display element encapsulant by irradiating it with radiation. [Effects of the Invention]

[0010] According to the present invention, a curable composition for encapsulating organic EL display elements can be obtained, which provides organic EL display elements with excellent inkjet coating properties and excellent element reliability. [Modes for carrying out the invention]

[0011] The following describes in detail matters related to the embodiments. In this specification, numerical ranges indicated using "~" include the numbers indicated before and after "~" as the lower and upper limits, respectively.

[0012] In this specification, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure in its main chain and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also include those that have a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may also include a linear structure or an alicyclic hydrocarbon structure as part of it. The ring structure of alicyclic hydrocarbon groups and aromatic hydrocarbon groups may have substituents consisting of hydrocarbon structures.

[0013] Curable composition for encapsulating organic EL display elements The curable composition for organic EL display element encapsulants (hereinafter also referred to as "the Composition") comprises a polymerizable compound and a cationic polymerization initiator. The viscosity of the Composition at 25°C is 3.0 mPa·s or more and 25.0 mPa·s or less, and the amount of water generated from the cured film when the cured film of the Composition is heated from 25°C to 200°C using TPD-MS is 1800 ppm by mass or less relative to the mass of the cured film.

[0014] The components contained in this composition, as well as other components that may be added as needed, are described below. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0015] <Polymerizable compound> Polymerizable compounds are a general term for compounds that harden when exposed to radiation or heat. Polymerizable compounds have one or more polymerizable functional groups (hereinafter also referred to as "polymerizable functional groups") in each molecule. Examples of radiation include electromagnetic waves such as visible light, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays, X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays.

[0016] From the viewpoint of reactivity to radiation or heat, polymerizable compounds contain a compound having at least one group selected from cationic polymerizable oxetanyl groups and oxyranyl groups as a polymerizable functional group. Polymerizable compounds may also contain polymerizable compounds other than those having at least one group selected from oxetanyl groups and oxyranyl groups. Examples of such polymerizable compounds include compounds having vinyl ether groups.

[0017] This composition preferably contains, as a cyclic ether compound, a polyfunctional oxetane compound having two or more oxetanyl groups in one molecule (compound (A)) and a polyfunctional epoxy compound having two or more oxiranyl groups in one molecule (compound (C)). Furthermore, in order to adjust the physical properties of the cured film formed from this composition, this composition preferably further contains, as a cyclic ether compound, a monofunctional oxetane compound having one oxetanyl group in one molecule (compound (B)). Compounds (A) to (C) will be described below. In compounds (A) to (C), if a compound contains both an oxetanyl group and an oxyranyl group in one molecule, the oxetanyl group takes precedence if the number of oxetanyl groups and oxyranyl groups in one molecule are the same. If the number of oxetanyl groups and oxyranyl groups in one molecule are different, the compound with the larger number of functional groups takes precedence. For example, a compound containing one oxetanyl group and one oxyranyl group in one molecule is a monofunctional oxetane compound (compound (B)), and a compound containing one oxetanyl group and two oxyranyl groups in one molecule is a polyfunctional epoxy compound (compound (C)).

[0018] • Polyfunctional oxetane compound (Compound (A)) A polyfunctional oxetane compound (compound (A)) is a compound having two or more oxetanyl groups in one molecule. Examples of polyfunctional oxetane compounds (compound (A)) include the compound represented by the following formula (1).

[0019] [ka]

[0020] In formula (1), R 1 and R 2 These are alkyl groups having 1 to 6 carbon atoms, independently of each other, and X 1 It is a divalent base, and n1 and n2 are independent integers between 0 and 5.

[0021] In the above equation (1), R1 and R 2 the alkyl group having 1 to 6 carbon atoms represented by may be linear or branched. From the viewpoint of reactivity of the compound represented by formula (1) to radiation or heat, R 1 and R 2 is preferably a linear alkyl group having 1 to 6 carbon atoms, more preferably a linear alkyl group having 1 to 4 carbon atoms, and still more preferably a methyl group or an ethyl group.

[0022] From the viewpoint of reactivity of the compound represented by formula (1) to radiation or heat, in the above formula (1), n1 and n2 are preferably 0 or 1.

[0023] In the above formula (1), X 1 examples of the divalent group represented by include a divalent chain hydrocarbon group, a divalent alicyclic hydrocarbon group, a divalent aromatic hydrocarbon group, and a group represented by the following formula (1a). *-Y 1 -X 2 -Y 2 -* (1a) In formula (1a), X 2 is an oxygen atom, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, and Y 1 and Y 2 are each independently a divalent group having 1 to 6 carbon atoms, and "*" represents a bonding site to an oxetanyl group.

[0024] X 1 examples of the divalent chain hydrocarbon group represented by include 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.

[0025] X 1Examples of divalent alicyclic hydrocarbon groups represented by include groups obtained by removing two hydrogen atoms from the ring or chain portion of an alicyclic hydrocarbon having a saturated or unsaturated aliphatic ring with 3 to 20 carbon atoms. Specific examples of rings possessed by divalent alicyclic hydrocarbon groups include monocyclic saturated alicyclic hydrocarbons such as cyclobutane rings, cyclopentane rings, cyclohexane rings, cycloheptane rings, and cyclooctane rings; monocyclic unsaturated alicyclic hydrocarbons such as cyclobutene rings, cyclopentene rings, cyclohexene rings, cycloheptene rings, and cyclooctene rings; polycyclic saturated alicyclic hydrocarbons such as decahydronaphthalene rings, octahydronaphthalene rings, norbornane rings, and bicyclo[2.2.2]octane rings; norbornene rings, tetracyclo[6.2.1.1 3,6 .0 2,7 Examples include polycyclic unsaturated alicyclic hydrocarbons such as dodeca-4-ene; and so on.

[0026] X 1 Examples of divalent aromatic hydrocarbon groups represented by include groups obtained by removing two hydrogen atoms from the ring portion of an aromatic hydrocarbon having a monocyclic or fused ring (e.g., a benzene ring, a naphthalene ring, or an anthracene ring) or from a chain-like hydrocarbon group portion as a substituent. When the divalent aromatic hydrocarbon group is a group obtained by removing two hydrogen atoms from a chain-like hydrocarbon group portion as a substituent, it may be a group obtained by removing two hydrogen atoms from one chain-like hydrocarbon group portion, or a group obtained by removing one hydrogen atom from each of two chain-like hydrocarbon group portions, and it is preferable that it is a group obtained by removing one hydrogen atom from each of two chain-like hydrocarbon group portions as substituents.

[0027] X 2 The divalent alicyclic hydrocarbon group and divalent aromatic hydrocarbon group represented by are X 1 Examples include divalent alicyclic hydrocarbon groups and divalent aromatic hydrocarbon groups represented by [the formula shown].

[0028] Y 1 and Y 2Examples of divalent groups having 1 to 6 carbon atoms, as represented by , include groups selected from divalent linear hydrocarbon groups having 1 to 6 carbon atoms, alkylene oxy groups having 1 to 6 carbon atoms, and ether groups having 2 to 6 carbon atoms.

[0029] From the viewpoint of reactivity to radiation or heat, the compound represented by formula (1) is preferably the compound represented by the following formula (1-1).

[0030] [ka]

[0031] In formula (1-1), R 1 , R 2 , and X 1 R in equation (1) 1 , R 2 , and X 1 It is synonymous with [the above].

[0032] Specific examples of compound (A) include, for example, 1,2-bis(oxetan-3-yl)ethane, 1,3-bis(oxetan-3-yl)propane, 1,4-bis(oxetan-3-yl)butane, 1,5-bis(oxetan-3-yl)pentane, 1,6-bis(oxetan-3-yl)hexane, 1,10-bis(oxetan-3-yl)decane (the compound represented by formula (1-1-1) below), 2,9-bis(oxetan-3-yl)decane, 3, Linear or branched ammonium compounds such as 8-bis(oxetan-3-yl)decane, 1,12-bis(oxetan-3-yl)dodecane, 2,11-bis(oxetan-3-yl)dodecane, 3,10-bis(oxetan-3-yl)dodecane, 1,18-bis(oxetan-3-yl)octadecane, 2,17-bis(oxetan-3-yl)octadecane, and 3,16-bis(oxetan-3-yl)octadecane (compounds represented by formula (1-1-2) below). Compounds in which two or more oxetanyl groups are substituted at the end or inside of the can; 1,3-bis(oxetane-3-ylmethyl)cyclopentane, 1,3-bis(3-methyloxetane-3-ylmethyl)cyclopentane, 1,3-bis(3-ethyloxetane-3-ylmethyl)cyclopentane, 1,3-bis(oxetane-3-ylmethyl)cyclohexane, 1,3-bis(3 Compounds in which two or more oxetanyl groups are substituted via alkylene groups on a cyclic alkane such as (-ethyloxetane-3-ylmethyl)cyclohexane, 1,4-bis(oxetane-3-ylmethyl)cyclohexane, 1,4-bis(3-methyloxetane-3-ylmethyl)cyclohexane, compounds represented by the following formula (1-1-3), and compounds represented by the following formula (1-1-4);1,2-Bis(3-methyloxetane-3-ylmethoxy)ethane, 1,2-Bis(3-ethyloxetane-3-ylmethoxy)ethane, 1,3-Bis(3-methyloxetane-3-ylmethoxy)propane, 1,3-Bis(3-ethyloxetane-3-ylmethoxy)propane, 1,4-Bis(3-methyloxetane-3-ylmethoxy)butane, 1,4-Bis(3-ethyloxetane-3-ylmethoxy)butane, 1,5-Bis(3-methyloxetane-3-ylmethoxy)pentane, 1,5-Bis(3-ethyloxetane-3-ylmethoxy) Compounds in which two or more oxetanyl groups are substituted via alkyloxy groups at the terminus or internally of an alkane such as methoxy)pentane, 1,6-bis(3-methyloxetane-3-ylmethoxy)hexane, 1,6-bis(3-ethyloxetane-3-ylmethoxy)hexane, 110-bis(3-methyloxetane-3-ylmethoxy)decane, 110-bis(3-ethyloxetane-3-ylmethoxy)decane; bis(3-ethyloxetane-3-ylmethyl)ether, ethylene glycol bis(3-ethyloxetane-3-ylmethyl)ether Ether compounds having two or more oxetanyl groups, such as triethylene glycol bis(3-ethyloxetane-3-ylmethyl) ether and tetraethylene glycol bis(3-ethyloxetane-3-ylmethyl) ether; 1,4-bis(3-methyloxetane-3-ylmethoxymethyl)benzene, 1,4-bis(3-ethyloxetane-3-ylmethoxymethyl)benzene, 1,3-bis(3-methyloxetane-3-ylmethoxymethyl)benzene, and 1,2-bis(3-ethyloxetane-3-ylmethoxymethyl)benzene. Aromatic compounds having two or more oxetanyl groups, such as 1,2-bis(3-methyloxetane-3-ylmethoxymethyl)benzene, 1,3-bis(3-ethyloxetane-3-ylmethoxymethyl)benzene, 4,4'-bis(3-methyloxetane-3-ylmethoxymethyl)biphenyl, 4,4'-bis(3-ethyloxetane-3-ylmethoxymethyl)biphenyl, 2,2'-bis(3-methyloxetane-3-ylmethoxymethyl)biphenyl, and 2,2'-bis(3-ethyloxetane-3-ylmethoxymethyl)biphenyl;Examples include compounds having a silyl ether structure and two or more oxetanyl groups, such as 1,3-bis(3-ethyloxetan-3-ylmethoxypropane)tetramethyldisiloxane, hydrolysis condensates of 3-[(3-ethyloxetan-3-yl)methoxy]propyltrialkoxysilane, and condensation reaction products of 3-ethyloxetan-3-ylmethanol and silanetetraol polycondensates.

[0033] [ka]

[0034] Compound (A) is not limited to the compounds exemplified above. However, from the viewpoint of lowering the dielectric constant of the cured film of this composition, it is preferable that compound (A) does not contain halogen atoms as substituents.

[0035] The number of polymerizable functional groups in one molecule of compound (A) is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. The molecular weight of compound (A) is preferably 50 to 800, more preferably 70 to 600, and even more preferably 100 to 500, as this facilitates adjusting the viscosity of the composition at 25°C to 3.0 to 25.0 mPa·s.

[0036] In this composition, the content of compound (A) is preferably 5 to 95% by mass of the total amount of polymerizable compounds in this composition, from the viewpoint of obtaining a cured film with excellent indentation modulus while reducing the dielectric constant of the cured film of this composition. From the viewpoint of obtaining a cured film with excellent indentation modulus, the content of compound (A) is more preferably 10% by mass or more, and even more preferably 30% by mass or more, of the total amount of polymerizable compounds in this composition. Furthermore, from the viewpoint of reducing the dielectric constant of the cured film, the content of compound (A) is more preferably 80% by mass or less, and even more preferably 70% by mass or less, of the total amount of polymerizable compounds in this composition.

[0037] • Monofunctional oxetane compound (Compound (B)) The monofunctional oxetane compound (compound (B)) is a compound containing one oxetanyl group in each molecule. By incorporating compound (B) into this composition, the viscosity of the composition and the dielectric constant of the cured film of this composition can be adjusted. Furthermore, because compound (B) has an oxetanyl group as a polymerizable functional group, it is highly reactive to radiation or heat, making it difficult for unreacted compound (B) to remain in the cured film. This reduces the amount of unreacted polymerizable compounds generated from the cured film, thereby suppressing the degradation of the organic EL display element. Examples of monofunctional oxetane compounds (compound (B)) include the compound represented by the following formula (2).

[0038] [ka]

[0039] In formula (2), R 11 and R 12 n11 and n12 are groups independently selected from alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, alkyloxy groups having 1 to 20 carbon atoms, alkenyloxy groups having 2 to 20 carbon atoms, and aryloxy groups having 6 to 20 carbon atoms, and n11 and n12 are integers from 0 to 6, independently of each other. However, the sum of n11 and n12 is 1 or greater and not greater than 6.

[0040] In equation (2) above, R 11 and R 12 A C1-C20 alkyl group and R represented by 11 and R 12 The alkenyl group, represented by , having 2 to 20 carbon atoms, may be linear or branched. In equation (2) above, R 11 and R 12 The aryl group, represented by , having 6 to 20 carbon atoms, is a group obtained by removing one hydrogen atom from a monocycle (e.g., a benzene ring) or a fused ring (e.g., a naphthalene ring, an anthracene ring). In formula (2) above, the alkyloxy group having 1 to 20 carbon atoms, the alkenyloxy group having 2 to 20 carbon atoms, and the aryloxy group having 6 to 20 carbon atoms are, respectively, R 11 and R 12 This group consists of an alkyl group with 1 to 20 carbon atoms, an alkenyl group with 2 to 20 carbon atoms, and an aryl group with 6 to 20 carbon atoms, all of which are bonded to an oxetanyl group via an oxygen atom.

[0041] C1-C20 alkyl groups, C2-C20 alkenyl groups, C6-C20 aryl groups, C1-C20 alkyloxy groups, C2-C20 alkenyloxy groups, and C6-C20 aryloxy groups may have substituents. Examples of substituents include trialkylsilyl groups. C1-C20 alkyl groups, C2-C20 alkenyl groups, C6-C20 aryl groups, C1-C20 alkyloxy groups, C2-C20 alkenyloxy groups, and C6-C20 aryloxy groups may be substituted with C2-C20 alkenyl groups, C6-C20 aryl groups, C1-C20 alkyloxy groups, C2-C20 alkenyloxy groups, and C6-C20 aryloxy groups, respectively. However, in this case, it is preferable that the sum of the number of carbon atoms does not exceed 20.

[0042] From the viewpoint of the reactivity of the compound represented by formula (2) to radiation or heat, it is preferable that in formula (2), n11 is 1 and n12 is 0 or 1.

[0043] From the viewpoint of reactivity to radiation or heat, the compound represented by formula (2) is preferably the compound represented by formula (2-1) below.

[0044] [ka]

[0045] In formula (2-1), R 11 and R 12 R in equation (2) 11 and R 12This is equivalent to the above, where n11 is 1 and n12 is 0 or 1.

[0046] Specific examples of compound (B) include, for example, 3-hexyloxetane, 3-heptyloxetane, 3-octyloxetane, 3-nonyloxetane, 3-decyloxetane, 3-dodecyloxetane, 3-(2-ethylhexyl)oxetane, 3-(2-ethylheptyl)oxetane, 3-(2-ethyloctyl)oxetane, 3-(2-ethylnonyl)oxetane, 3-(2-ethyldecyl)oxetane, 3-(2-ethyldodecyl)oxetane, 3-(2-hexylnonyl)oxetane, 3-(2-hexyldecyl)oxetane, 3-(2-hexyl Sildodecyl)oxetane, 3-(3-ethylhexyl)oxetane, 3-(3-ethylheptyl)oxetane, 3-(3-ethyloctyl)oxetane, 3-(3-ethylnonyl)oxetane, 3-(3-ethyldecyl)oxetane, 3-methyl-3-hexyloxetane, 3-methyl-3-heptyloxetane, 3-methyl-3-octyloxetane, 3-methyl-3-nonyloxetane, 3-methyl-3-decyloxetane, 3-methyl-3-dodecyloxetane, 3-methyl-3-(2-ethylhexyl)oxetane, 3-methyl-3-(2 -ethylheptyl)oxetane, 3-methyl-3-(2-ethyloctyl)oxetane, 3-methyl-3-(2-ethylnonyl)oxetane, 3-methyl-3-(2-ethyldecyl)oxetane, 3-methyl-3-(2-ethyldodecyl)oxetane, 3-methyl-3-(2-hexylnonyl)oxetane, 3-methyl-3-(2-hexyldecyl)oxetane, 3-methyl-3-(2-hexyldodecyl)oxetane, 3-methyl-3-(3-ethylhexyl)oxetane, 3-methyl-3 -(3-ethyloctyl)oxetane, 3-methyl-3-(3-ethylnonyl)oxetane, 3-methyl-3-(3-ethyldecyl)oxetane, 3-ethyl-3-hexyloxetane, 3-ethyl-3-heptyloxetane, 3-ethyl-3-octyloxetane, 3-ethyl-3-nonyloxetane, 3-ethyl-3-decyloxetane, 3-ethyl-3-dodecyloxetane, 3-ethyl-3-(2-ethylhexyl)oxetane, 3-ethyl-3-(2-ethylheptyl)oxetane, 3-ethyl-3-(2-ethyloctyl)oxetane,3-ethyl-3-(2-ethylnonyl)oxetane, 3-ethyl-3-(2-ethyldecyl)oxetane, 3-ethyl-3-(2-ethyldodecyl)oxetane, 3-ethyl-3-(2-hexylnonyl)oxetane, 3-ethyl-3-(2-hexyldecyl)oxetane, 3-ethyl-3-(2-hexyldodecyl)oxetane, 3-ethyl-3-(3-ethylhexyl)oxetane, 3-ethyl-3-(3-ethylheptyl)oxetane, 3-ethyl-3-(3-ethyloctyl)oxetane, 3-ethyl-3-(3-ethylnonyl)oxetane, 3 Compounds in which one or two linear or branched alkyl groups are substituted on the oxetane ring, such as ethyl-3-(3-ethyldecyl)oxetane; 3-hexyloxymethyloxetane, 3-heptyloxymethyloxetane, 3-octyloxymethyloxetane, 3-nonyloxymethyloxetane, 3-decyloxymethyloxetane, 3-dodecyloxymethyloxetane, 3-(2-ethylhexyloxymethyl)oxetane, 3-(2-ethylheptyloxymethyl)oxetane, 3-(2-ethyloctyloxymethyl)oxetane, 3-(2-ethyl (Nyloxymethyl)oxetane, 3-(2-ethyldecyloxymethyl)oxetane, 3-(2-ethyldodecyloxymethyl)oxetane, 3-(2-hexylnonyloxymethyl)oxetane, 3-(2-hexyldecyloxymethyl)oxetane, 3-(2-hexyldodecyloxymethyl)oxetane, 3-(3-ethylhexyloxymethyl)oxetane, 3-(3-ethylheptyloxymethyl)oxetane, 3-(3-ethyloctyloxymethyl)oxetane, 3-(3-ethylnonyloxymethyl)oxetane, 3-(3-ethyldecyl Oxetane (2-ethylhexyloxymethyl), 3-methyl-3-hexyloxymethyl oxetane, 3-methyl-3-heptyloxymethyl oxetane, 3-methyl-3-octyloxymethyl oxetane, 3-methyl-3-nonyloxymethyl oxetane, 3-methyl-3-decyloxymethyl oxetane, 3-methyl-3-dodecyloxymethyl oxetane, 3-methyl-3-(2-ethylhexyloxymethyl)oxetane, 3-methyl-3-(2-ethylheptyloxymethyl)oxetane, 3-methyl-3-(2-ethyloctyloxymethyl)oxetane,3-methyl-3-(2-ethylnonyloxymethyl)oxetane, 3-methyl-3-(2-ethyldecyloxymethyl)oxetane, 3-methyl-3-(2-ethyldodecyloxymethyl)oxetane, 3-methyl-3-(2-hexylnonyloxymethyl)oxetane, 3-methyl-3-(2-hexyldecyloxymethyl)oxetane, 3-methyl-3-(2-hexyldodecyloxymethyl)oxetane, 3-methyl-3-(3-ethylhexyloxymethyl)oxetane, 3-methyl-3-(3-ethylheptyloxymethyl)oxetane, 3 -Methyl-3-(3-ethyloctyloxymethyl)oxetane, 3-methyl-3-(3-ethylnonyloxymethyl)oxetane, 3-methyl-3-(3-ethyldecyloxymethyl)oxetane, 3-ethyl-3-hexyloxymethyl oxetane, 3-ethyl-3-heptyloxymethyl oxetane, 3-ethyl-3-octyloxymethyl oxetane, 3-ethyl-3-nonyloxymethyl oxetane, 3-ethyl-3-decyloxymethyl oxetane, 3-ethyl-3-dodecyloxymethyl oxetane, 3-ethyl-3-(2-ethylhexyl Oxetane (2-ethylheptyloxymethyl), 3-ethyl-3-(2-ethyloctyloxymethyl), 3-ethyl-3-(2-ethylnonyloxymethyl), 3-ethyl-3-(2-ethyldecyloxymethyl), 3-ethyl-3-(2-ethyldodecyloxymethyl), 3-ethyl-3-(2-hexylnonyloxymethyl), 3-ethyl-3-(2-hexyldecyloxymethyl), 3-ethyl-3-(2-hexyldodecyl Compounds in which an alkyl group is substituted on an oxetane ring, such as oxymethyl)oxetane, 3-ethyl-3-(3-ethylhexyloxymethyl)oxetane, 3-ethyl-3-(3-ethylheptyloxymethyl)oxetane, 3-ethyl-3-(3-ethyloctyloxymethyl)oxetane, 3-ethyl-3-(3-ethylnonyloxymethyl)oxetane, 3-ethyl-3-(3-ethyldecyloxymethyl)oxetane; 3-methoxyoxetane, 3-methyl-3-methoxyoxetane, 3-ethyl-3-methoxyoxetane,Compounds in which an alkyloxy group or alkenyloxy group is substituted on an oxetane ring, such as 3-allyloxyoxetane, 3-methyl-3-allyloxyoxetane, and 3-ethyl-3-allyloxyoxetane; compounds in which an aryl group is substituted on an oxetane ring, such as phenyloxetane; compounds in which an alkyl group is substituted on an oxetane ring, such as 3-phenoxymethyloxetane, 3-methyl-3-(phenoxymethyl)oxetane, and 3-ethyl-3-(phenoxymethyl)oxetane; 3-(3-(triethoxysilyl) Examples include compounds in which an alkyl group or alkyloxyalkyl group is substituted on an oxetane ring, such as 3-(triethoxysilyl)propyl)oxetane, 3-ethyl-3-(3-(triethoxysilyl)propyl)oxetane, 3-(3-(triethoxysilyl)propoxymethyl)oxetane, 3-methyl-3-(3-(triethoxysilyl)propoxymethyl)oxetane, and 3-ethyl-3-(3-(triethoxysilyl)propoxymethyl)oxetane.

[0047] Examples of the structures of the compounds exemplified above are shown in the following formulas (2-1-1) to (2-1-21).

[0048] [ka]

[0049] Compound (B) is not limited to the compounds exemplified above. However, from the viewpoint of lowering the dielectric constant of the cured film of this composition, it is preferable that compound (B) does not contain halogen atoms as substituents.

[0050] The molecular weight of compound (B) is preferably 50 to 800, more preferably 70 to 600, and even more preferably 100 to 500, as this facilitates adjusting the viscosity of the composition at 25°C to 3.0 to 25.0 mPa·s.

[0051] In this composition, the content of compound (B) is preferably 5 to 70% by mass of the total amount of polymerizable compounds in this composition, from the viewpoint of obtaining a cured film with excellent indentation modulus while reducing the dielectric constant of the cured film of this composition, and from the viewpoint of reducing the viscosity of this composition. From the viewpoint of reducing the dielectric constant of the cured film and reducing the viscosity of this composition, the content of compound (B) is more preferably 15% by mass or more, and even more preferably 20% by mass or more, of the total amount of polymerizable compounds in this composition. Furthermore, from the viewpoint of reducing the dielectric constant of the cured film and obtaining a cured film with excellent indentation modulus, the content of compound (B) is more preferably 60% by mass or less, and even more preferably 40% by mass or less, of the total amount of polymerizable compounds in this composition.

[0052] • Polyfunctional epoxy compound (compound (C)) A polyfunctional epoxy compound (compound (C)) is any compound that has two or more oxiranyl groups in one molecule. Examples of polyfunctional epoxy compounds (compound (C)) include the compound represented by the following formula (3). R 21 -X 21 -R 22 (3) In formula (3), R 21 and R 22 These are groups that are independent of each other and are represented by the following formula (3a), X 21 It is a single bond or a divalent group.

[0053] [ka]

[0054] In formula (3a), R 23 n21 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms, n21 is an integer from 0 to 3, and "*" represents X 21 This represents a combination of two things.

[0055] In the above equation (3a), R 23 The alkyl group having 1 to 6 carbon atoms, represented by R, may be linear or branched. 23Examples of aryl groups with 6 to 20 carbon atoms represented by this formula include phenyl group, methylphenyl group, ethylphenyl group, dimethylphenyl group, and diethylphenyl group. R 23 Of these, alkyl groups or phenyl groups having 1 to 3 carbon atoms are preferred. n21 is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0056] From the viewpoint of the reactivity of the compound represented by formula (3) to radiation or heat, R 21 and R 22 Each of the above is preferably a substituted or unsubstituted 3,4-epoxycyclohexyl group (1,2-epoxycyclohexane-4-yl group), and more preferably a 3,4-epoxycyclohexyl group.

[0057] In equation (3) above, X 21 Examples of divalent groups represented by the formula (3b) include divalent linear hydrocarbon groups, divalent alicyclic hydrocarbon groups, and divalent aromatic hydrocarbon groups, as well as groups represented by the formula (3b) below. *-Y 21 -X 22 -Y 22 -* (3b) In formula (3b), Y 21 and Y 22 These are, independently of each other, single bonds or divalent groups with 1 to 6 carbon atoms, X 22 The group is selected from an oxygen atom and a divalent group represented by the following formula (3c), and "*" represents a bond with the oxyranyl group. *-C(R 24 )(R 25 )-* (3c) (In formula (3c), R 24 and R 25 These are, independently of each other, an alkyl group or phenyl group having 1 to 3 carbon atoms, or R 24 and R 25 An oxyranyl group or oxetanyl group is formed when these atoms bond to each other via an oxygen atom, and "*" represents Y 21 and Y 22 (This represents a combination of two elements.)

[0058] In the above equation (3), X 21 Examples of divalent hydrocarbon groups represented by include divalent linear hydrocarbon groups, divalent alicyclic hydrocarbon groups, and divalent aromatic hydrocarbon groups, where X in formula (1) above 1 Examples include divalent chain hydrocarbon groups, divalent alicyclic hydrocarbon groups, and groups similar to divalent aromatic hydrocarbon groups.

[0059] In the above formula (3b), Y 21 and Y 22 As a divalent group having 1 to 6 carbon atoms represented by the above formula (1a), Y 1 and Y 2 Examples include divalent groups with 1 to 6 carbon atoms represented by .

[0060] In the above formula (3c), R 24 and R 25 The oxyranyl group or oxetanyl group formed by the bonding of these groups to each other via an oxygen atom is preferably an unsubstituted oxyranyl group or oxetane-3,3-diyl group, from the viewpoint of the reactivity of the compound represented by formula (3) to radiation or heat.

[0061] Specific examples of compound (C) include, for example, compounds in which two 3,4-epoxycyclohexyl groups are bonded by a single bond, such as 4,4'-bis(1,2-epoxycyclohexane); and compounds in which two 3,4-epoxycyclohexyl groups are bonded by a single bond, such as (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, and 2,2-bis(3,4-epoxycyclohexyl)butane. Examples include compounds with hexyl groups substituted; compounds in which two 3,4-epoxycyclohexyl groups are substituted on a divalent alicyclic hydrocarbon group, such as 1,1-bis(3,4-epoxycyclohexyl)cyclohexane and 1,1-bis(3,4-epoxycyclohexyl)-3,3,5-trimethylcyclohexane; and compounds having an oxetane ring, such as 3,3-bis(1,2-epoxycyclohexane-4-ylmethoxymethyl)oxetane and 3,3-bis(1,2-epoxycyclohexane-4-ylethoxymethyl)oxetane.

[0062] Compound (C) is not limited to the compounds exemplified above. However, from the viewpoint of lowering the dielectric constant of the cured film of this composition, it is preferable that compound (C) does not contain halogen atoms as substituents.

[0063] The number of polymerizable functional groups that compound (C) has in one molecule is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. The molecular weight of compound (C) is preferably 50 to 800, more preferably 70 to 600, and even more preferably 100 to 500, as this facilitates adjusting the viscosity of the composition at 25°C to 3.0 to 25.0 mPa·s.

[0064] In this composition, the content of compound (C) is preferably 5 to 60% by mass of the total amount of polymerizable compounds in this composition, from the viewpoint of obtaining a cured film with excellent indentation modulus while lowering the dielectric constant of the cured film of this composition, and from the viewpoint of lowering the viscosity of this composition. From the viewpoint of lowering the dielectric constant of the cured film and lowering the viscosity of this composition, the content of compound (C) is more preferably 45% by mass or less, and even more preferably 35% by mass or less, of the total amount of polymerizable compounds in this composition. Furthermore, from the viewpoint of obtaining a cured film with excellent indentation modulus, the content of compound (C) is more preferably 5% by mass or more, and even more preferably 20% by mass or more, of the total amount of polymerizable compounds.

[0065] The total amount of compound (A), compound (B), and compound (C) in this composition is 85% by mass or more of the total amount of polymerizable compounds contained in this composition. When the total amount of compound (A), compound (B), and compound (C) is 85% by mass or more of the total amount of polymerizable compounds contained in this composition, a balance can be maintained between the low dielectric constant and the indentation modulus of the cured film obtained from this composition, and unreacted polymerizable compounds are less likely to remain in the cured film, thereby reducing the amount of unreacted polymerizable compounds generated from the cured film and suppressing the degradation of the organic EL display element. The total amount of compound (A), compound (B), and compound (C) in this composition is more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more, based on the total amount of polymerizable compounds contained in this composition.

[0066] Other polymerizable compounds This composition may contain only compound (A) and compound (C) as polymerizable compounds, or it may contain only compound (A), compound (B), and compound (C) from the viewpoint of adjusting the viscosity of the composition and the dielectric constant of the cured film of the composition to a suitable range. Furthermore, for the purpose of adjusting the curability and viscosity of the composition, etc., this composition may further contain polymerizable compounds other than compound (A), compound (B), and compound (C) (hereinafter also referred to as "other polymerizable compounds"). Examples of other polymerizable compounds include monofunctional oxirane compounds having one oxiranyl group in one molecule, monofunctional vinyl ether compounds having one vinyl ether group in one molecule, and polyfunctional vinyl ether compounds having two or more vinyl ether groups in one molecule.

[0067] Examples of monofunctional oxirane compounds include cyclohexene oxide, 1-methyl-1,2-epoxycyclohexane, 1,2-epoxy-4-vinylcyclohexane, ethyl glycidyl ether, butyl glycidyl ether, and 1,2-epoxytetradecane. Examples of monofunctional vinyl ether compounds include cyclohexyl vinyl ether, ethylhexyl vinyl ether, and hydroxyethyl vinyl ether.

[0068] Examples of polyfunctional vinyl ether compounds include compounds having multiple 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, and dipentaerythritol hexanyl ether, as well as alkylene oxide modified or caprolactone modified compounds thereof.

[0069] 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 even more preferably 2% by mass or less, based on the total amount of polymerizable compounds contained in this composition, from the viewpoint of achieving a low dielectric constant of the cured film and excellent indentation modulus, as well as reducing the amount of outgassing from the cured film.

[0070] The molar ratio of oxetanyl groups to oxyranyl groups in the polymerizable compound (oxetanyl group:oxyranyl group) is preferably 0.5:1 to 15:1. By setting the molar ratio of oxyranyl groups to oxetanyl groups within the above range, the curing reactivity of this composition can be improved. Furthermore, the amount of outgassing from the cured film can be minimized while sufficiently achieving a low dielectric constant of the cured film. The molar ratio of oxyranyl groups to oxetanyl groups in the polymerizable compound (oxetanyl group:oxyranyl group) is more preferably 1:1 to 4:1.

[0071] <Polymerization initiator> The polymerization initiator can be any substance that generates a protic acid or Lewis acid in response to radiation or heat. Such polymerization initiators can be appropriately selected and used from among known photocationic polymerization initiators or thermal cationic polymerization initiators. From the viewpoint of suppressing device degradation, the polymerization initiator is preferably a photocationic polymerization initiator. Examples of photocationic polymerization initiators include ionic photoacid generating type and nonionic photoacid generating type polymerization initiators.

[0072] Examples of ionic photoacid-generating photocationic polymerization initiators include onium salt compounds, halogen-containing compounds, sulfone compounds, sulfonic acid compounds, sulfonimide compounds, and diazomethane compounds.

[0073] Specific examples of onium salt compounds include aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, or (2,4-cyclopentadiene-1-yl)[(1-methylethyl)benzene]-Fe cations, where the cation portion is aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, or (2,4-cyclopentadiene-1-yl)[(1-methylethyl)benzene]-Fe cation. As the cation moiety of the onium salt compound, aromatic sulfonium is preferable, and examples thereof include a sulfonium cation represented by the following formula (4).

[0074]

Chemical Formula

[0075] In formula (4), Ar 1 and Ar 2 are each independently a group represented by formulae (4a) to (4d); R 31 to R 37 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, an alkylcarbonyloxy group having 1 to 6 carbon atoms, an alkylcarbonylthio group having 1 to 6 carbon atoms, or an alkoxycarbonyloxy group having 1 to 6 carbon atoms; and n31 is 0 or 1. Provided that when one of R 36 and R 37 is an alkoxy group having 1 to 6 carbon atoms, an alkylcarbonyloxy group having 1 to 6 carbon atoms, or an alkoxycarbonyloxy group having 1 to 6 carbon atoms, the other is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or an alkylcarbonylthio group having 1 to 6 carbon atoms; and * indicates the bonding position to the sulfur atom to which Ar 1 bonds.

[0076] In formula (4) above, R 31 to R 37 are preferably each independently 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; R 31 to R 35 are more preferably a hydrogen atom; and R 36 and R 37 are more preferably a methyl group.

[0077] As the anion moiety of the onium salt compound, from the viewpoint of reducing the amount of water generated from a cured film of the present composition, GaF4 -or [GaArf4] - (wherein Arf is a phenyl group substituted with 2 or more fluorine atoms or trifluoromethyl groups), a gallium anion selected from the group consisting of PF6 - or [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) a substituted or unsubstituted hexafluorophosphate anion represented by, BF4 - or [BArf4] - a borate anion represented by, and an anion moiety selected from SbF6 - are mentioned. [GaArf4] - and "Arf" in [BArf4] - includes, for example, pentafluorophenyl group, difluorophenyl group, trifluoromethylphenyl group, bis(trifluoromethyl)phenyl group, and the like. [PF k (C p F 2p+1 ) 6-k includes, for example, tris(trifluoromethyl)trifluorophosphate anion, tris(perfluoroethyl)trifluorophosphate anion, tris(perfluoropropyl)trifluorophosphate anion, tris(perfluoroisopropyl)trifluorophosphate anion, bis(trifluoromethyl)tetrafluorophosphate anion, bis(perfluoroethyl)tetrafluorophosphate anion, bis(perfluoropropyl)tetrafluorophosphate anion, bis(perfluoroisopropyl)tetrafluorophosphate anion, and the like.

[0078] Among these, if the cationic polymerization initiator is a sulfonium salt containing a gallium anion or a sulfonium salt containing a substituted or unsubstituted hexafluorophosphate anion, the amount of superacid remaining in the cured film is reduced. Therefore, the decomposition of ether bonds in the cured film is suppressed, which is preferable because it suppresses the generation of low-boiling-point components such as alcohols and aldehydes. Furthermore, the dehydration reaction by superacids against terminal hydroxyl groups and hydroxyl groups of low-boiling-point components in the cured film is suppressed, which is preferable because it can suppress the amount of water generated. Also, [GaArf4] - The gallium anion represented by [PF] is a gallium atom bonded to a gallium atom by two or more electron-withdrawing phenyl groups substituted with fluorine or trifluoromethyl groups. k (C p F 2p+1 ) 6-k ] - The perfluoroalkyl substituted derivative of the hexafluorophosphate anion represented by (C p F 2p+1 Because it has a highly electron-withdrawing perfluoroalkyl group represented by ), it acts as a relatively strong acid, which is thought to further enhance the reactivity of the polymerizable compound and reduce the amount of unreacted polymerizable compound remaining in the cured film. However, this is merely speculation and does not limit the present invention in any way.

[0079] Commercially available products can be used as ionic photoacid-generating photocationic polymerization initiators. For example, a cation part represented by the above formula (4) and [GaArf4] - Commercially available photocationic polymerization initiators consisting of an anion moiety represented by the above formula (4) and [PF include the trade names "CPI-310FG" and "VC-1FG" (both manufactured by Sunapro Co., Ltd.). k (C p F 2p+1 ) 6-k ] -Commercially available photocationic polymerization initiators consisting of an anion moiety represented by the above formula (4) and [BArf4] include the trade names "CPI-210S" and "CPI-410S" (both manufactured by Sunapro Co., Ltd.). In addition, a cation moiety represented by the above formula (4) and [BArf4] - Commercially available photocationic polymerization initiators consisting of an anion part represented by the formula include "CPI-410B" (manufactured by Sunapro Co., Ltd.) and others.

[0080] Examples of nonionic photoacid-generating photocationic polymerization initiators include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenolsulfonic acid esters, diazonaphthoquinones, N-hydroxyimidosulfonates, and oxime ester-based carboxylic acid esters.

[0081] In this composition, the content of the polymerization initiator is usually 0.1 to 10 parts by mass per 100 parts by mass of the total amount of polymerizable compounds contained in the composition. Preferably, the content of the polymerization initiator is 7 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the total amount of polymerizable compounds. By setting the content of the polymerization initiator within the above range, the curability of this composition can be improved, and a highly transparent cured film can be obtained.

[0082] <Other ingredients> In addition to the polymerizable compound and polymerization initiator described above, this composition may further contain components different from the polymerizable compound and polymerization initiator (hereinafter also referred to as "other components"). Examples of other components include sensitizers, polymerization inhibitors, antioxidants, and surfactants.

[0083] • Sensitizer Sensitizers are used to minimize the amount of polymerization initiator used, thereby increasing the transparency of the cured film. Specific examples of sensitizers include, for example, polynuclear aromatics such as pyrene, perylene, triphenylene, anthracene, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 3,7-dimethoxyanthracene, and 9,10-dipropyloxyanthracene; xanthenes such as fluorescein, eosin, erythrosine, rhodamine B, and rose bengal; xanthones such as xanthone, thioxanthone, dimethylthioxanthone, diethylthioxanthone (2,4-diethylthioxanthen-9-one, etc.), and isopropylthioxanthone (2-isopropylthioxanthone, etc.); cyanines such as thiacarbocyanine and oxacarbocyanine; and merocyanine and carbomerocyanine. Examples include merocyanines; thiazines such as thionine, methylene blue, and toluidine blue; acridines such as acridine orange, chloroflavin, and acriflavin; acridines such as acridone and 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, and 2,3,6,7-tetrahydro-9-methyl-1H,5H,11H[l]benzopyrano[6,7,8-ij]quinoridine-11-non; rhodacyanines; oxonols; anthraquinones; squaryliums; styryls; and others.

[0084] Among these, in order to reduce the impact on organic EL display devices, the sensitizer is preferably one that is excited by light with a wavelength of 395 nm, and anthracene, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 3,7-dimethoxyanthracene, and 9,10-dipropyloxyanthracene are more preferred.

[0085] When a sensitizer is incorporated into this composition, the amount of sensitizer is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.15 to 3 parts by mass, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. By keeping the amount within the above range, the transparency of the cured film can be further enhanced.

[0086] • Polymerization inhibitors / antioxidants This composition may further contain at least one compound selected from the group consisting of polymerization inhibitors and antioxidants. Further inclusion of a polymerization inhibitor in this composition can improve its storage stability.

[0087] Polymerization inhibitors are not limited to the following, but examples include hydroquinone, p-methoxyphenol, p-benzoquinone, naphthoquinone, phenanthraquinone, tolquinone, 2,5-diacetoxy-p-benzoquinone, 2,5-dicapoxy-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-paracresolhydroquinone monomethyl ether, phenothiazine, alpha-naphthol, acetamidine acetate, acetamidine sulfate, phenylhydrazine hydrochloride, hydrazine hydrochloride, and trimethylbenzylammonium chloride. Examples include iodide, laurylpyridinium chloride, cetyltrimethylammonium chloride, phenyltrimethylammonium chloride, trimethylbenzylammonium oxalate, di(trimethylbenzylammonium)oxalate, trimethylbenzylammonium malate, trimethylbenzylammonium tartarate, trimethylbenzylammonium glycolate, phenyl-β-naphthylamine, parabenzylaminophenol, di-β-naphthylparaphenylenediamine, dinitrobenzene, trinitrotoluene, picric acid, cyclohexanone oxime, pyrogallol, tannic acid, resorcinol, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylamine hydrochloride, dimethylaniline hydrochloride, and dibutylamine hydrochloride.

[0088] When a polymerization inhibitor is added to this composition, the amount of polymerization inhibitor is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.01 to 3 parts by mass, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. By keeping the amount within the above range, it is possible to suppress viscosity increases due to unnecessary thermal energy, as well as gelation or curing reactions, while maintaining the viscosity of this composition within an appropriate range even after long-term distribution or storage, thereby ensuring good wettability (and consequently, inkjet coating properties).

[0089] Antioxidants are used to improve the storage stability of the curable composition by preventing oxidative degradation of the composition. Examples of antioxidants include phenolic antioxidants, sulfuric antioxidants, and phosphorusic antioxidants.

[0090] Specific examples of antioxidants include phenolic antioxidants such as monophenols including 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; 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} Examples include bisphenols such as [Tyl]2,4,8,10-tetraoxaspiro[5,5]undecane; 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 high molecular weight phenols such as tocopherol.

[0091] Examples of sulfur-based antioxidants include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate. Phosphorus-based antioxidants include diphenyl phosphite, diphenylisodecyl phosphite, phenyldiisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecylpentaerythritol phosphite, tris(2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis(octadecyl) phosphite, cyclic neopentanetetraylbis(2,4-di-tert-butylphenyl) phosphite, and cyclic neopentanetetraylbis(2,4-di-tert-butyl-6-methylphenyl) phosphite. Phosphates such as 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; are examples.

[0092] Each antioxidant may be used individually, but it is particularly preferable to use them in combination with phenolic / sulfur-based or phenolic / phosphorus-based antioxidants. Furthermore, commercially available phenolic antioxidants (e.g., IRGANOX 1010 (product name) manufactured by BASF Japan Ltd.) and commercially available phosphorus-based antioxidants (e.g., IRGAFOS 168 (product name) manufactured by BASF Japan Ltd.) may be used individually, or they may be used in combination.

[0093] When an antioxidant is added to this composition, the antioxidant content is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.01 to 3 parts by mass, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. By keeping the content within the above range, it is possible to suppress viscosity increases due to unnecessary thermal energy, as well as gelation or curing reactions, while maintaining the viscosity of this composition within an appropriate range even after long-term distribution or storage, thereby ensuring good wettability (and consequently, inkjet coating properties).

[0094] Furthermore, in order to enhance the storage stability of this composition, heat stabilizers such as methylenequinone or 2-dimethylaminomethanol, as described in Japanese Patent Publication No. 2020-518952, may be further added to this composition.

[0095] • Surfactants Surfactants can be used to improve the applicability of this composition (specifically, its wetting properties and reduction of uneven application) and the surface flatness of the cured film. Examples of surfactants include fluorinated surfactants, silicone surfactants, and nonionic surfactants.

[0096] Specific examples of surfactants include fluorine-based surfactants, such as the following product names: Megafac F-171, F-172, F-173, F-251, F-430, F-552, F-554, F-556, F-557, F-559, F-560, F-563 (all manufactured by DIC Corporation); Florard FC430, FC431 (both manufactured by 3M Japan Ltd.); Asahiguard AG710, etc. Examples include Flon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106, and S-611 (all manufactured by AGC Seimi Chemical Co., Ltd.); Polyflow No. 75 and No. 95 (both manufactured by Kyoeisha Chemical Co., Ltd.); FTX-218 (manufactured by Neos Co., Ltd.); and F-Top EF301, EF303, and EF352 (all manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.).

[0097] Examples of silicone-based surfactants include the following product 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 DuPont-Toray Specialty Materials Co., Ltd.); Organosiloxane Polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.); BYK-300, BYK-306, BYK-310, BYK-330, BYK-333, BYK-335, BYK-341, BYK-344, BYK-370, BYK-340, BYK-345 (all manufactured by BIC Chemie Japan Co., Ltd.).

[0098] 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, and polyethylene glycol distearate.

[0099] When a surfactant is incorporated into this composition, the surfactant content is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 3 parts by mass, and even more preferably 0.1 to 2 parts by mass, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0100] Other components, in addition to those mentioned above, include, for example, softeners, plasticizers, adhesion aids, and organic solvents. The proportions of these components are appropriately selected according to each component, within a range that does not impair the effects of this disclosure.

[0101] Organic solvents may be added to this composition for purposes such as dissolving each component. On the other hand, from the viewpoint of enabling the formation of a cured film (particularly an organic encapsulation layer protecting the organic light-emitting layer of an organic EL display element) without heat treatment, it is preferable to minimize the amount of organic solvent used. Specifically, the content of organic solvent in this 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, even 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.

[0102] When this composition contains an organic solvent, it is preferable to use an organic solvent that can dissolve or disperse each component of this composition and does not react with each component. Specifically, examples include alcohols, ketones, esters, ethers, aromatic hydrocarbons, and amides.

[0103] Specific examples of these include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and methyl-3-methoxypropionate; ethers such as polyoxyethylene lauryl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and diethylene glycol methyl ethyl ether; aromatic hydrocarbons such as benzene, toluene, and xylene; and amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0104] <Preparation of curable composition> This composition can be prepared by mixing compound (A), compound (B), compound (C), and a polymerization initiator, as well as other polymerizable compounds and other components as needed. From the viewpoint of producing a curable composition with good sensitivity and forming a cured film with a high sealing effect, the total amount of compound (A), compound (B), and compound (C) is preferably 85 parts by mass or more, more preferably 90 parts by mass or more, and even more preferably 95 parts by mass or more, per 100 parts by mass of the total amount of this composition.

[0105] <Viscosity of curable composition> This composition has a viscosity measured using an E-type viscometer at 25°C and 20 rpm, in the range of 3.0 to 25.0 mPa·s. When the viscosity of this composition is 25.0 mPa·s or less, it exhibits good wetting and spreading properties when applied to a substrate by inkjet coating, and coating unevenness due to repellency, etc., can be sufficiently suppressed. Furthermore, when the viscosity of this composition is 3.0 mPa·s or more, it can ensure sufficient film thickness when applied to a substrate, forming an organic encapsulation layer that exhibits a sufficient sealing effect. This composition is suitable as a curable composition for inkjet coating.

[0106] From the viewpoint of obtaining a curable composition with excellent inkjet coating properties, the viscosity of this composition is more preferably 23.0 mPa·s or less, even more preferably 21.0 mPa·s or less, and even more preferably 19 mPa·s or less. Furthermore, from the viewpoint of stable inkjet ejection and ensuring sufficient film thickness, the viscosity of this composition is more preferably 5.0 mPa·s or more, and even more preferably 10.0 mPa·s or more. In this specification, the viscosity of the curable composition is a value measured in accordance with JIS K2283:2000.

[0107] 《Cured film and organic EL display element》 The cured film of this disclosure (hereinafter also referred to as "the cured film") is formed by the above-described composition. According to this composition, a cured film can be obtained that suppresses moisture generation, has a low dielectric constant, and excellent indentation modulus. Such a composition can be used as various materials, for example, in the sealing structure of organic EL display elements, microlenses, anti-reflective coatings, and diffraction gratings for AR elements. Furthermore, this composition can also be used as a hole-filling material or a material for forming a planarization film in HID (Hole In a Display area) structures. Moreover, because this composition allows for the formation of a cured film with low moisture permeability, prevention of foreign matter intrusion, and excellent bending resistance, it can also be used as a material for forming a protective coating layer in the bent portion of a flexible display or in the bend portion where wiring extending from the display area to the outside is provided. An example of a coating layer in a bent portion is the micro-coating layer described in International Publication No. 2016 / 009925. The micro-coating layer can be formed by slit coating or by inkjet coating. This composition is useful because it can be used with any of these coating methods. This composition is particularly useful as a encapsulation structure forming composition, i.e., as an encapsulant for organic electroluminescent display elements (organic EL display elements), by performing thin film encapsulation (TFE) on the organic electroluminescent display element (organic EL display element) to form an encapsulated structure.

[0108] <Amount of moisture generated from heating of the cured film> Components remaining in the cured film of a polymerizable composition may cause the cured film to decompose, generating moisture and low-boiling point components. On the other hand, moisture and low-boiling point components generated from the cured film can lead to device degradation and impair device reliability, so it is desirable to minimize their amount. In this invention, the amount of moisture generated by heating is used as an indicator of cured film decomposition, and if the amount of moisture generated from the cured film detected when heated from 25°C to 200°C using TPD-MS (Temperature Programmed Desorption-Mass Spectrometry) is 1800 ppm by mass or less relative to the mass of the cured film, degradation of the organic EL display element can be suppressed. From the viewpoint of further suppressing the degradation of the organic EL display element, it is preferable that the amount of moisture generated from the cured film detected when heated from 25°C to 200°C using TPD-MS is 1000 ppm by mass or less, and more preferably 500 ppm by mass or less, relative to the mass of the cured film. There is no particular lower limit to the amount of moisture generated from the cured film detected when heated from 25°C to 200°C using TPD-MS. For details on how to measure the amount of moisture generated from the cured film, follow the method described in the examples below.

[0109] <Dielectric constant of hardened film> From the viewpoint of the insulating properties of the cured film, it is preferable that the dielectric constant of the cured film at 25°C and 100kHz is 2.80 or less. When the dielectric constant at these measurement conditions is 2.80 or less, the dielectric constant of the low dielectric constant layer can be sufficiently low when forming a low dielectric constant layer of a device employing a touch panel system (e.g., an organic EL light-emitting device) using a curable composition, thereby suppressing malfunctions during use of the touch panel and improving the reliability of the device. From the viewpoint of forming a low dielectric constant layer exhibiting desired performance, the dielectric constant of the cured film at 25°C and 100kHz is more preferably 2.75 or less, and even more preferably 2.73 or less. There is no particular lower limit to the dielectric constant of the cured film. The dielectric constant of the cured film at 25°C and 100kHz is, for example, 2.00 or more.

[0110] For details on the dielectric constant measurement method, please refer to the following: a UV-LED lamp with a wavelength of 395 nm was used, with an illuminance of 1,000 mW / cm².2 Furthermore, the integrated light intensity is 3,000 mJ / cm². 2 The cured film obtained by irradiating the composition with ultraviolet light under these conditions is measured at 25°C and a frequency of 100kHz. Details of the dielectric constant measurement method are as described in the examples below.

[0111] <Indentation modulus> From the viewpoint of durability, the indentation modulus of the cured film is preferably 1.0 GPa or higher. When the indentation modulus of the cured film is 1.0 GPa or higher, the cured film has an appropriate hardness, which suppresses the occurrence of cracks when the inorganic film described later is formed on this cured film, and improves film formation resistance. In film formation resistance, film formation refers to the formation of an inorganic film by chemical vapor deposition (CVD), physical vapor deposition (PVD), etc. From the viewpoint of further suppressing the occurrence of cracks, the indentation modulus of the cured film is more preferably 1.1 GPa or higher, and even more preferably 1.2 GPa or higher. There is no particular upper limit to the indentation modulus. For example, the indentation modulus is 5.0 GPa or lower. The indentation modulus of the cured film is a value obtained by the indentation method. Details of the indentation modulus of the cured film are described in the examples below.

[0112] Organic EL display element The organic EL display element of this disclosure has an organic light-emitting layer sealed by the cured film. The organic EL display element is composed of a laminate comprising the cured film and the organic light-emitting layer, as well as various other layers such as an anode layer, a hole injection layer, a hole transport layer, an electron injection layer, and a cathode layer. The organic EL display element may have an inorganic film (inorganic sealing layer) between the cured film and the organic light-emitting layer, and an inorganic film (inorganic sealing layer) may be further provided on the side of the cured film opposite to the side facing the organic light-emitting layer.

[0113] Manufacturing method for organic EL display elements The cured film and the organic EL display element in which the organic light-emitting layer is sealed with the cured film can be manufactured using the composition by a method comprising the following steps 1 and 2. (Step 1) A step of applying the composition to the organic light-emitting layer forming surface of a substrate on which an organic light-emitting layer has been formed. (Step 2) A step to form a sealing structure (organic sealing layer) by curing the composition by irradiating it with radiation. The following provides a detailed explanation of each step.

[0114] [Process 1: Coating process] In this process, a coating film made of this composition is formed on the organic light-emitting layer-forming surface of a substrate on which an organic light-emitting layer has been formed, by applying this composition to the organic light-emitting layer-forming surface. The substrate on which this composition is applied has a laminate formed thereon, which includes various layers in addition to the organic light-emitting layer, such as an anode layer, a hole injection layer, a hole transport layer, an electron injection layer, and a cathode layer, and this laminate constitutes an organic EL display element. The organic light-emitting layer-forming surface on which this composition is applied may be covered with an inorganic film (inorganic encapsulation layer). Examples of inorganic materials constituting the inorganic film include silicon nitride (SiNx) and silicon oxide (SiOx). In this case, a thin film encapsulation layer including an organic encapsulation layer and an inorganic encapsulation layer is formed on the organic light-emitting layer as an encapsulation structure.

[0115] Methods for applying this composition include, for example, spray coating, roll coating, spin coating, slit die coating, bar coating, and inkjet coating. Of these, inkjet coating is preferred in terms of throughput and thin film formation. This composition exhibits excellent curability despite its low viscosity and suppresses the occurrence of uneven coating; therefore, it is preferable to apply this composition to the organic light-emitting layer forming surface by inkjet coating.

[0116] [Process 2: Curing process] In this step, a cured film is obtained by irradiating the coated film formed in step 1 with radiation to cure the coated film. Examples of radiation include ultraviolet light, far ultraviolet light, visible light, X-rays, electron beams, and other charged particle beams. Among these, ultraviolet light is preferred, and for example, ultraviolet light with a wavelength of 350 to 400 nm can be preferably used as the irradiation light. The integrated amount of radiation is 50 to 10,000 mJ / m 2This is preferable. This makes it possible to obtain an organic EL display element coated with an organic encapsulation layer made of this composition. The thickness of the cured film is usually 0.5 to 15 μm.

[0117] The organic encapsulation layer formed by this composition may be further coated with an inorganic film (inorganic encapsulation layer). Examples of inorganic materials constituting the inorganic film include silicon nitride (SiNx) and silicon oxide (SiOx). When a thin-film encapsulation layer including an organic encapsulation layer and an inorganic encapsulation layer is provided on an organic EL display element, forming the organic encapsulation layer with this composition makes the organic encapsulation layer appropriately hard. This makes it possible to suppress the occurrence of cracks in the organic encapsulation layer even when an inorganic encapsulation layer is further formed on the surface of the organic encapsulation layer.

[0118] The organic EL display element of this disclosure, manufactured by a method including steps 1 and 2 described above, comprises an organic light-emitting layer and an organic encapsulation layer made of the composition, with the organic light-emitting layer encapsulated by the organic encapsulation layer. Therefore, in the organic EL display element of this disclosure, the intrusion of moisture into the organic light-emitting layer can be sufficiently suppressed, thereby suppressing problems caused by moisture, specifically the occurrence of dark spots and a decrease in light-emitting characteristics such as brightness and luminous efficiency. Furthermore, in the organic EL display element of this disclosure, outgassing from the organic encapsulation layer is minimal, and the dielectric constant of the organic encapsulation layer is sufficiently low. Such an organic EL display element of this disclosure is useful, for example, as an organic EL lighting device or an organic EL display device.

[0119] The above-described disclosure provides the following [1] to

[17] . [1] A curable composition for encapsulating organic EL display elements, comprising a polymerizable compound and a cationic polymerization initiator, wherein the polymerizable compound contains a compound having at least one group selected from an oxetanyl group and an oxyranyl group, the viscosity at 25°C is 3.0 mPa·s or more and 25.0 mPa·s or less, and the amount of water generated from the cured film detected when the cured film of the curable composition is heated from 25°C to 200°C using a TPD-MS is 1800 ppm by mass or less relative to the mass of the cured film. [2] The curable composition for organic EL display element encapsulant according to [1], wherein the dielectric constant of the cured film formed from the curable composition is 2.80 or less at a frequency of 100 kHz at 25°C. [3] The curable composition for organic EL display element encapsulant according to [1] or [2], wherein the indentation modulus of the cured film formed from the curable composition is 1.00 GPa or more. [4] A curable composition for encapsulating organic EL display elements according to any one of [1] to [3], further comprising a sensitizer. [5] The curable composition for encapsulating organic EL display elements according to [4], wherein the sensitizer is a sensitizer that is excited by light with a wavelength of 395 nm. [6] The curable composition for organic EL display element encapsulant according to any one of [1] to [5], wherein the cationic polymerization initiator is a sulfonium salt containing a gallium anion. [7] The curable composition for organic EL display element encapsulant according to any one of [1] to [6], wherein the cationic polymerization initiator is a sulfonium salt containing a substituted or unsubstituted hexafluorophosphate anion. [8] A curable composition for encapsulating organic EL display elements according to any one of [1] to [7], wherein the polymerizable compound contains a polyfunctional oxetane compound and a polyfunctional epoxy compound. [9] The curable composition for organic EL display element encapsulant according to [8], wherein the polymerizable compound further contains a monofunctional oxetane compound.

[10] The curable composition for organic EL display element encapsulant according to [9], wherein the content of the monofunctional oxetane compound in the polymerizable compound is 15% by mass or more and 60% by mass or less.

[11] A curable composition for encapsulating organic EL display elements according to any one of [1] to

[10] , further comprising a surfactant.

[12] A curable composition for organic EL display element encapsulant according to any one of [1] to

[11] , further comprising at least one selected from the group consisting of polymerization inhibitors and antioxidants.

[13] A curable composition for encapsulating organic EL display elements, as described in any one of [1] to

[12] , for inkjet coating.

[14] A cured film formed using a curable composition for organic EL display element encapsulant described in any one of [1] to

[13] .

[15] An organic EL display element in which the organic light-emitting layer is sealed with the cured film described in

[14] .

[16] A method for manufacturing an organic EL display element, comprising the following steps 1 and 2. (Step 1) A step of applying one of the curable compositions for organic EL display element encapsulants from [1] to

[13] to the organic light-emitting layer forming surface of a substrate on which an organic light-emitting layer has been formed. (Step 2) A step of forming a sealing structure by curing the curable composition for the organic EL display element encapsulant by irradiating it with radiation.

[17] A method for manufacturing an organic EL display element according to

[16] , wherein the curable composition for the organic EL display element encapsulant is applied to the organic light-emitting layer forming surface by inkjet coating. [Examples]

[0120] The present invention will be described in detail below 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.

[0121] <Preparation of curable composition> The components used in the preparation of the curable compositions of the examples and comparative examples are shown. (Polyfunctional oxetane compounds) • (A-1): OXT-221 (3,3'-(oxybismethylene)bis(3-ethyloxetane), manufactured by Toagosei Co., Ltd.) • (A-2): Compound (A-2) synthesized in Synthesis Example 1 below. • (A-3): Compound (A-3) synthesized in Synthesis Example 2 below.

[0122] [ka]

[0123] (Monofunctional oxetane compounds) (B-1): Oxetane 10 as described in paragraph

[0094] of Japanese Patent Publication No. 2024-082267 • (B-2): OXT-212 (3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, manufactured by Toagosei Co., Ltd.) (Polyfunctional epoxy compound) • (C-1): CEL2021P (Alicyclic epoxy resin: Manufactured by Daicel Corporation) • (C-2): TTA800 (Alicyclic epoxy resin: manufactured by Tetra Corporation) (Polymerization initiator) • (D-1): CPI-310FG (a salt consisting of a cation represented by formula (4) and a gallium anion, triarylsulfonium-tetrakispentafluorophenyl gallate, manufactured by Sunapro Co., Ltd.) • (D-2): VC-1FG (a salt consisting of a cation represented by formula (4) and a gallium anion, triarylsulfonium-tetrakispentafluorophenyl gallate, manufactured by Sunapro Co., Ltd.) • (D-3): CPI-210S (a salt consisting of a cation represented by formula (4) and a borate anion, 4-(phenylthio)phenyldiphenylsulfonium tris(pentafluoroethyl)trifluorophosphate, manufactured by Sunapro Co., Ltd.) • (D-4): CPI-410B (a salt consisting of a cation represented by formula (4) and a borate anion, manufactured by Sunapro Co., Ltd.) • (D-5): CPI-310B (a salt consisting of a cation represented by formula (4) and a borate anion, triarylsulfonium-tetrakispentafluorophenylborate, manufactured by Sunapro Co., Ltd.) (Sensitizer) • (E-1): UVS-1331 (9,10-dibutoxyanthracene, manufactured by Air Water Performance Chemicals Inc.) (Polymerization inhibitor) • (F-1): Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (manufactured by ADEKA Corporation) (Surfactants) • (G-1): Megafuck F-563 (Fluorine oligomer, manufactured by DIC Corporation)

[0124] [Synthesis Example 1] Synthesis of polyfunctional oxetane compound (A-2) In a 2L round-bottom flask equipped with a stirring bar, 108g of 3-ethyloxetane-3-ylmethanol, 930mL of dichloromethane, 112.6g of triethylamine, and 7.6g of 1-methylimidazole were added, and the mixture was cooled to below 10°C. At the same temperature, 177g of tosylloride was added in portions and stirred for 30 minutes, after which the reaction was continued overnight at room temperature under a nitrogen atmosphere. Subsequently, the reaction mixture was diluted by pouring it into approximately 1000mL of dichloromethane, and after sequential washing with 2M hydrochloric acid, saturated NaHCO3 aqueous solution, and deionized water, the organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure using a rotary evaporator. The resulting residue was dried under reduced pressure to obtain 228g of the crude solid product of compound (1a: toluenesulfonic acid (3-ethyloxetane-3-ylmethyl)). The obtained crude product was used directly in the next reaction. In a 3L round-bottom flask equipped with a stirring bar, 228g of compound (1a), 106g of lithium bromide monohydrate, and 2200mL of acetone were added and reacted under reflux conditions under a nitrogen atmosphere for 2.5 hours. Insoluble matter was then removed by Celite filtration, and the mixture was concentrated under reduced pressure at 200 Torr in a rotary evaporator until no more acetone distilled. 1.5L of diisopropyl ether was added to the resulting residue, insoluble matter was removed by Celite filtration, and the mixture was concentrated under reduced pressure at 180 Torr in a rotary evaporator until no more solvent distilled. Next, most of the solvent was removed by atmospheric distillation using a Widmer fractionation column. Further reduced-pressure distillation was carried out at 80°C under reduced pressure of 20-21 Torr to obtain 136g of compound (1b: 3-bromomethyl-3-ethyloxetane). A stirring bar was placed in a 1 L round-bottom flask, which was fitted with a thermometer, a Liebig condenser, and a dropping funnel, and then nitrogen-purged. 17.4 g of 1,10-octanediol and 200 mL of DMF were added to this flask. Then, 12 g of sodium hydride (60%, oily) was added while the flask was bathed in ice, and the mixture was stirred under a nitrogen atmosphere for 30 minutes. Next, a solution of compound (1b) dissolved in 200 mL of DMF was added dropwise over 20 minutes, ensuring that the internal temperature did not exceed 10°C. The mixture was then stirred under a nitrogen atmosphere at 80°C for 3 hours. After that, the reaction solution was cooled to below 10°C, 100 mL of deionized water was added, and the mixture was stirred at room temperature for 30 minutes. The resulting solution was extracted three times with a mixed solvent of hexane and ethyl acetate in a 3:1 (volume ratio). The resulting organic layer was further extracted three times with deionized water. The organic layer was concentrated under reduced pressure using a rotary evaporator, and the resulting residue was purified by silica gel column chromatography to obtain 33.2 g of compound (A-2: 1,10-bis(3-ethyloxetane-3-ylmethoxy)decane).

[0125] [ka]

[0126] [Synthesis Example 2] Synthesis of polyfunctional oxetane compound (A-3) A stirring bar was placed in a 1 L round-bottom flask, which was then fitted with a thermometer, a Liebig condenser, and a dropping funnel, and nitrogen-purged. 46.4 g of 3-ethyl-3-oxetane methanol and 200 mL of DMF were added. Then, 24 g of sodium hydride (60%, oily) was added while the flask was bathed in ice, and the mixture was stirred under a nitrogen atmosphere for 30 minutes. Next, a solution of 96.8 g of allyl bromide dissolved in 200 mL of DMF was added dropwise over 20 minutes, ensuring that the internal temperature did not exceed 10°C. The mixture was then stirred at 80°C under a nitrogen atmosphere for 1 hour. After that, the reaction solution was cooled to below 10°C, 100 mL of deionized water was added, and the mixture was stirred at room temperature for 30 minutes. The resulting solution was extracted three times with a mixed solvent of hexane and ethyl acetate in a 3:1 (volume ratio). The resulting organic layer was further extracted three times with deionized water. Next, the reduced pressure was adjusted to 140 Torr, and the organic layer was concentrated using a rotary evaporator. The resulting residue was then heated to 100°C under atmospheric pressure to remove the solvent. Finally, vacuum distillation was performed under conditions of 32 mmHg / 110°C to obtain 40.6 g of compound (2a: 3-allyloxymethyl-3-ethyloxetane). In a 200 mL four-necked flask fitted with a stirring bar, thermometer, and Liebig condenser, 18.7 g of compound (2a), 60 g of toluene, 0.85 g of tris(1,3-divinyl 1,1,3,3-tetramethyl-disiloxane)-diplatinum(0) (Karstedt catalyst) at a platinum equivalent concentration of 2% by mass, and 8.1 g of 1,1,3,3-tetramethyldisiloxane were sequentially charged and stirred at an internal temperature of 70°C for 9 hours. After cooling the reaction solution to room temperature, 60 mL of deionized water was added and stirred at room temperature for 30 minutes. The resulting solution was extracted three times with a mixed solvent of hexane and ethyl acetate in a 3:1 (volume ratio). The organic layer was concentrated under reduced pressure using a rotary evaporator, and the resulting residue was purified by silica gel column to obtain 15.4 g of compound (A-3: 1,3-bis(3-ethyloxetane-3-ylmethoxypropane)tetramethyldisiloxane).

[0127] [ka]

[0128] [Example 1] Under atmospheric conditions, a curable composition for organic EL display element encapsulant was prepared by mixing 90 parts by mass of (A-1) as a polyfunctional oxetane compound, 10 parts by mass of (C-1) as a polyfunctional alicyclic epoxy compound, 1 part by mass of (D-4) as a polymerization initiator, 0.1 parts by mass of (F-1) as a polymerization inhibitor, and 1 part by mass of (G-1) as a surfactant.

[0129] [Examples 2-10 and Comparative Examples 1-4] Curable compositions for organic EL display element encapsulants for Examples 2-10 and Comparative Examples 1-4 were prepared in the same manner as in Example 1, except that the composition was changed as shown in Table 1.

[0130] "evaluation" For the curable compositions for organic EL display element encapsulants prepared in Examples 1-10 and Comparative Examples 1-4, the viscosity of the curable compositions for organic EL display element encapsulants, the amount of heat-generated water from the cured film, the dielectric constant and indentation modulus of the cured film, and the inkjet coating properties, organic EL display element reliability, and film formation durability of the curable compositions for organic EL display element encapsulants were measured by the method described below. The measurement results are shown in Table 1.

[0131] <Viscosity> In accordance with JIS K2283:2000, the viscosity (mPa·s) of each curable composition for organic EL display element encapsulants was measured at 25°C and 20 rpm using an E-type viscometer (RE-85L, cone rotor type: 1°34'×R24, manufactured by Toki Sangyo Co., Ltd.).

[0132] <Amount of moisture generated from heating of the cured film> The amount of water generated during heating of the cured film of each curable composition obtained in the examples and comparative examples was measured by TPD-MS as shown below. A special heating device manufactured by Toray Research Center, Inc. was used as the heating apparatus. A GC-MS QP2020 manufactured by Shimadzu Corporation was used as the MS apparatus. First, each curable composition for encapsulating organic EL display elements was coated to a thickness of 8 μm onto a silicon substrate (6-inch silicon monitor wafer (Type P), manufactured by Electronics End Materials Corporation) using a spin coater. Next, a UV-LED lamp (UniJet E110Hi HD:U395A-F50, manufactured by Ushio Inc.) was used to apply ultraviolet light at a wavelength of 395 nm at an irradiance of 1000 mW / cm². 2 Furthermore, the cumulative light intensity is 3000 mJ / cm². 2 The coated film was cured by irradiation under the specified conditions. Furthermore, to eliminate the effect of adsorbed water, helium gas was injected into the TPD-MS instrument for 60 minutes after the sample was placed inside. Subsequently, the amount of water generated by heating (mass ppm) was measured by heating from 25°C to 200°C at a heating rate of 10°C / min. The amount of moisture generated during heating was calculated using the following formula. Amount of moisture generated by heating (mass ppm) = (Amount of moisture generated (mass) / Mass of cured film before heating) × 10 6

[0133] <Dielectric constant of hardened film> A substrate on which ITO was deposited to a thickness of 30 nm on alkali-free glass was coated with each curable composition for encapsulating organic EL display elements using a spin coater to a cured thickness of 8 μm. Next, a UV-LED lamp (UniJet E110Hi HD:U395A-F50, manufactured by Ushio Inc.) was used to apply ultraviolet light at a wavelength of 395 nm at an irradiance of 1000 mW / cm². 2 Furthermore, the cumulative light intensity is 3000 mJ / cm². 2 A cured film was prepared by irradiation under the specified conditions. Subsequently, aluminum was deposited to a thickness of 50 nm onto the resin surface of the cured film to prepare a test specimen for dielectric constant measurement. The dielectric constant of the obtained test specimen was measured using a dielectric constant measuring device at 25°C and 100 kHz. A 4284A LCR meter (manufactured by Hewlett Packard) was used as the dielectric constant measuring device. <Indentation modulus> Each curable composition for encapsulating organic EL display elements was coated to a thickness of 8 μm using a spin coater. Then, a UV-LED lamp (UniJet E110Hi HD:U395A-F50, manufactured by Ushio Inc.) was used to apply ultraviolet light with a wavelength of 395 nm at an irradiance of 1000 mW / cm². 2 Furthermore, the cumulative light intensity is 3000 mJ / cm². 2 After curing the coated film by irradiation under these conditions, the indentation modulus (GPa) was measured using an indenter. A Fischer Picodenter HM500 was used as the measuring device (indenter).

[0134] <Inkjet coating properties> On an evaluation substrate in which a SiNx film with a thickness of 100 nm was deposited on an alkali-free glass substrate, a 10 cm square coating film was fabricated by inkjet ejection of each curable composition for organic EL display element encapsulants from the inkjet head of a piezo-type inkjet printer at a pitch of 50 μm × 50 μm. Furthermore, after 5 minutes, ultraviolet light with a wavelength of 395 nm was applied at an irradiance of 1000 mW / cm using a UV-LED lamp (UniJet E110Hi HD:U395A-F50, manufactured by Ushio Inc.). 2 Furthermore, the cumulative light intensity is 3000 mJ / cm². 2 The coated film was cured by irradiation under the specified conditions. During this process, the voltage conditions of the inkjet head were adjusted to ensure a cured film thickness of 8 μm, thereby controlling the amount of ink dot ejected per drop. The resulting cured film was evaluated according to the following criteria. Acceptable: No unevenness in the coating or uncoated areas are observed visually. Unacceptable: At least one of the following is observed visually: uneven coating and / or uncoated areas.

[0135] <Reliability of Organic EL Display Elements> Multiple array substrates were prepared, each having a glass substrate (OA-10, manufactured by Nippon Electric Glass Co., Ltd.) with an array of transparent ITO electrodes formed on it, and a planarization layer with a thickness of 3 μm having contact holes in which only a portion of the transparent ITO electrodes were exposed. An Al film with a thickness of 100 nm was formed on the planarization layer by DC sputtering using an Al target. An ITO film with a thickness of 20 nm was formed on the Al film by DC magnetron reactive sputtering using an ITO target. A substrate with an anode layer formed in this manner, consisting of an Al film and an ITO film, was used. A coating film was formed on the anode layer using a resist material (Optomer NN803, manufactured by JSR Corporation), and a series of processes including i-line (wavelength 365 nm) irradiation, development, running water washing, air drying, and heat treatment were performed to form a pixel-defining layer with a 2 mm square aperture region on a portion of the anode layer. The substrate with the anode and pixel-defining layer formed was moved to a vacuum deposition chamber, and the deposition chamber was set to 1E -4After evacuating to Pa, molybdenum oxide (MoOx), which has hole-injecting properties, was deposited on the substrate by resistance heating evaporation at a deposition rate of 0.004 to 0.005 nm / sec using a deposition mask with a predetermined pattern to form a hole-injecting layer with a thickness of 1 nm. On the hole-injecting layer, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD), which has hole-transporting properties, was deposited by resistance heating evaporation under the same evacuating conditions as the hole-injecting layer, using a deposition mask with a predetermined pattern to form a hole-transporting layer with a thickness of 35 nm. The deposition rate was 0.2 to 0.3 nm / sec. On the hole-transporting layer, tris(8-quinolinolato)aluminum, an alkylate complex, was deposited as a green light-emitting material by resistance heating evaporation under the same deposition conditions as the hole-transporting layer, using a deposition mask with a predetermined pattern to form an organic light-emitting layer with a thickness of 35 nm. The deposition rate was 0.5 nm / sec or less. On the organic light-emitting layer, lithium fluoride was deposited by resistance heating evaporation under the same exhaust conditions as the hole injection layer to form an electron injection layer with a thickness of 0.8 nm. The deposition rate was 0.004 nm / sec or less. Subsequently, magnesium and Ag were simultaneously deposited on the electron injection layer by resistance heating evaporation under the same exhaust conditions as the hole injection layer to form a first cathode layer with a thickness of 5 nm. The deposition rate was 0.5 nm / sec or less. Next, the substrate was transferred to another deposition chamber (sputtering chamber), and a second cathode layer with a thickness of 100 nm was formed on the first cathode layer by RF sputtering using an ITO target. In this way, a substrate on which an evaluation organic EL display element was formed was obtained. A thin film encapsulation layer was formed on the substrate on which the organic EL display element was formed, according to the following procedure. The substrate on which the organic EL display element was formed was transferred to a deposition chamber (sputtering chamber), and an inorganic encapsulation layer (SiNx film) with a thickness of 100 nm was formed on the cathode layer by RF sputtering using a SiNx target. Subsequently, the organic EL display element was transferred into an N2-substituted glove box, and a curable composition for the encapsulant of each organic EL display element was ejected in a predetermined pattern using a piezo inkjet printer. Then, ultraviolet light with a wavelength of 395 nm and an illuminance of 1000 mW / cm² was used with a UV-LED lamp (UniJet E110Hi HD:U395A-F50, manufactured by Ushio Inc.). 2 Furthermore, the cumulative light intensity is 3000 mJ / cm². 2 The curable composition was cured by irradiation, forming an organic encapsulation layer with a thickness of 8 μm. Furthermore, the organic EL display element was transferred to a deposition chamber (sputtering chamber), and an inorganic encapsulation layer (SiNx film) with a thickness of 100 nm was formed on the organic encapsulation layer by RF sputtering using a SiNx target. In this way, an organic EL device was obtained. Each of the obtained organic EL devices was stored for 100 hours under 85°C and 85% humid heat conditions, and then a forward current of 10 mA / cm² was applied. 2 A 2mm square light-emitting section was energized, and the appearance of the light-emitting section (unlit areas: dark spots) was observed. It was evaluated based on the following criteria. Good: No dark spots larger than 0.1 mm in diameter were observed within the 2 mm square light-emitting area. OK: Within a 2mm square light-emitting area, one to two dark spots with a diameter of 0.1mm or more are observed. Failure: Three or more dark spots with a diameter of 0.1 mm or more are observed within a 2 mm square light-emitting area.

[0136] <Film formation resistance> Each curable composition for encapsulating organic EL display elements was applied to alkali-free glass using a spin coater to a cured thickness of 8 μm. Next, a UV-LED lamp (UniJet E110Hi HD:U395A-F50, manufactured by Ushio Inc.) was used to apply ultraviolet light at a wavelength of 395 nm at an irradiance of 1000 mW / cm². 2Furthermore, the cumulative light intensity is 3000 mJ / cm². 2 The coated film was cured by irradiation under the specified conditions. Subsequently, an inorganic encapsulation layer (SiNx film) with a thickness of 100 nm was formed on the organic encapsulation layer by RF sputtering using a SiNx target, and the surface was observed using SEM. Good: The inorganic encapsulation layer has no wrinkles on its surface. Acceptable: There are extremely small wrinkles on the surface of the inorganic encapsulation layer. Unacceptable: The inorganic encapsulation layer has wrinkles all over its surface.

[0137] [Table 1]

[0138] As shown in Table 1, the curable compositions for organic EL display element encapsulants of Examples 1 to 10 had a viscosity of 3.0 mPa·s to 25.0 mPa·s and exhibited excellent inkjet coating properties. Furthermore, the amount of water generated from the cured film of the curable compositions for organic EL display element encapsulants of Examples 1 to 10, detected when heated from 25°C to 200°C using TPD-MS, was 1800 ppm by mass or less relative to the mass of the cured film, and the reliability of the organic EL display elements with the organic light-emitting layer encapsulated by the cured film of these curable compositions for organic EL display element encapsulants was excellent. In particular, the organic EL display elements prepared using the curable compositions for organic EL display element encapsulants of Examples 2 and 4 to 10, which contain a sulfonium salt containing tetrakis(pentafluorophenyl)gallium anion or a sulfonium salt containing tris(perfluoroethyl)trifluorophosphate anion as a cationic polymerization initiator, exhibited particularly excellent element reliability. Furthermore, the dielectric constant of the cured films formed from the curable compositions for organic EL display element encapsulants of Examples 5 to 10, which contain 15 to 60% by mass of a monofunctional oxetane compound, at a frequency of 100 kHz at 25°C was 2.80 or less, and the organic EL display elements in which the organic light-emitting layer was encapsulated by the cured films of these curable compositions for organic EL display element encapsulants exhibited excellent element reliability. In addition, the indentation modulus of the cured films formed from the curable compositions for organic EL display element encapsulants of Examples 1 to 10 was 1.00 GPa or more, indicating excellent film formation durability.

[0139] In contrast, when the cured films of the curable compositions for organic EL display element encapsulants of Comparative Examples 1 and 2 were heated from 25°C to 200°C using a TPD-MS, the amount of water generated from the cured films was greater than 1800 ppm by mass. As a result, organic EL display elements whose organic light-emitting layers were encapsulated with the cured films of these curable compositions exhibited poor element reliability. Furthermore, the viscosity of the curable compositions for organic EL display element encapsulants of Comparative Examples 3 and 4 was greater than 25.0 mPa·s, resulting in poor inkjet coating properties.

Claims

1. It comprises a polymerizable compound and a cationic polymerization initiator. The polymerizable compound contains a compound having at least one group selected from an oxetanyl group and an oxyranyl group, The viscosity at 25°C is 3.0 mPa·s or more and 25.0 mPa·s or less. The amount of water generated from the cured film of a curable composition when heated from 25°C to 200°C using TPD-MS is 1800 ppm by mass or less relative to the mass of the cured film. A curable composition for encapsulating organic EL display elements.

2. The curable composition for organic EL display element encapsulant according to claim 1, wherein the dielectric constant of the cured film formed from the curable composition at a frequency of 100 kHz at 25°C is 2.80 or less.

3. The curable composition for organic EL display element encapsulant according to claim 1, wherein the indentation modulus of the cured film formed from the curable composition is 1.00 GPa or more.

4. The curable composition for organic EL display element encapsulant according to claim 1, further comprising a sensitizer.

5. The curable composition for organic EL display element encapsulant according to claim 4, wherein the sensitizer is a sensitizer that is excited by light with a wavelength of 395 nm.

6. The curable composition for organic EL display element encapsulant according to claim 1, wherein the cationic polymerization initiator is a sulfonium salt containing a gallium anion.

7. The curable composition for organic EL display element encapsulant according to claim 1, wherein the cationic polymerization initiator is a sulfonium salt containing a substituted or unsubstituted hexafluorophosphate anion.

8. The curable composition for organic EL display element encapsulant according to claim 1, wherein the polymerizable compound contains a polyfunctional oxetane compound and a polyfunctional epoxy compound.

9. The curable composition for organic EL display element encapsulant according to claim 8, wherein the polymerizable compound further contains a monofunctional oxetane compound.

10. The curable composition for organic EL display element encapsulant according to claim 9, wherein the content of the monofunctional oxetane compound in the polymerizable compound is 15% by mass or more and 60% by mass or less.

11. The curable composition for organic EL display element encapsulant according to claim 1, further comprising a surfactant.

12. The curable composition for organic EL display element encapsulant according to claim 1, further comprising at least one selected from the group consisting of polymerization inhibitors and antioxidants.

13. A curable composition for an organic EL display element encapsulant according to claim 1, for use with inkjet coating.

14. A cured film formed using the curable composition for organic EL display element encapsulant according to any one of claims 1 to 13.

15. An organic EL display element in which an organic light-emitting layer is sealed with the cured film described in claim 14.

16. A method for manufacturing an organic EL display element, comprising the following steps 1 and 2. (Step 1) A step of applying the curable composition for organic EL display element encapsulant according to any one of claims 1 to 13 to the organic light-emitting layer forming surface of a substrate on which an organic light-emitting layer has been formed. (Step 2) A step of forming a sealing structure by curing the curable composition for the organic EL display element encapsulant by irradiating it with radiation.

17. A method for manufacturing an organic EL display element according to claim 16, wherein the curable composition for the organic EL display element encapsulant is applied to the organic light-emitting layer forming surface by inkjet coating.

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