Curable composition, cured film, organic el element, and method for manufacturing organic el element

Abstract

The invention provides a curable composition capable of forming a cured film with little generation of outgassing, a cured film, an organic EL element, and a method for manufacturing the organic EL element. A curable composition containing: a monofunctional oxetane compound (A1); a polyfunctional epoxy compound (A2) which is at least one selected from the group consisting of a polyfunctional oxetane compound and a polyfunctional oxetane compound; and a polymerization initiator. The monofunctional oxetane compound (A1) has a GPC peak area ratio of 5.0% or less as determined by a specific hardenability evaluation by GPC. When a cured film, which is obtained by irradiating a coating film formed from a curable composition with ultraviolet light having a wavelength of 395 nm under the conditions of an illuminance of 1000 mW / cm < 2 > and a cumulative light amount of 1000 mJ / cm < 2 >, is heated at 110 DEG C, the amount of outgassing detected by a headspace method is less than 400 ppm.

Description

TECHNICAL FIELD

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

[0002] An organic electroluminescence element (organic EL element) is a light-emitting element having a stacked structure including an anode, an organic light-emitting layer, and a cathode. The organic EL element is widely utilized in various applications such as display devices or lighting devices.

[0003] The organic light-emitting layer included in the organic EL element is easily deteriorated by contact with moisture or oxygen, and there are concerns that, for example, a region in which light is not emitted locally due to moisture that has penetrated into the element (hereinafter also referred to as "dark spot") is formed along with long-time driving, or the light-emitting properties are reduced due to contact with moisture or oxygen. Therefore, in the past, a sealing structure has been provided in the organic EL element, and the organic light-emitting layer has been prevented from contacting with moisture or oxygen by the sealing structure (for example, refer to Patent Document 1 or Patent Document 2). In Patent Document 1 and Patent Document 2, a sealing structure in which the organic light-emitting layer is covered with a cured film formed from a curable composition including an organic material such as a polymerizable compound and a polymerization initiator is disclosed.

[0004] [Related Art Documents]

[0005] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2020-26515

[0007] [Patent Document 2] International Publication No. 2021 / 010226 SUMMARY

[0008] [Problems to be Solved by the Invention]

[0009] In the case where a sealing structure formed from a curable composition is provided in an organic EL element, gas is sometimes easily generated from the sealing structure due to a component of the curable composition (for example, an unreacted polymerizable compound, or a solvent, or the like) or a decomposition product of a polymer obtained by curing the polymerizable compound that remains in the sealing structure. The gas generated from the sealing structure can possibly deteriorate the organic EL element, and therefore, in the organic EL element, it is required to reduce the generation of gas from the sealing structure as much as possible.

[0010] The present application has been made in view of the above-described problem, and provides a curable composition that can form a cured film in which the generation of gas is less.

[0011] [Technical Means for Solving the Problem]

[0012] Provided are a curable composition, a cured film, and an organic EL element and a method for producing the same.

[0013] 〔1〕A curable composition comprising: a monofunctional oxetane compound (A1); a multifunctional epoxy compound (A2) which is at least one selected from the group consisting of a multifunctional oxetane compound and a multifunctional oxirane compound; and a polymerization initiator, wherein the curable composition has a GPC peak area ratio of 5.0% or less, as calculated by a curability evaluation shown below using gel permeation chromatography (GPC), and a cured film obtained by irradiating a coating film formed from the curable composition with ultraviolet rays having a wavelength of 395 nm under conditions of an irradiation intensity of 1000 mW / cm 2 and a cumulative light amount of 1000 mJ / cm 2 has an outgassing amount of 400 ppm or less, as detected by a headspace method, when heated.

[0014] Curability evaluation: a cured film obtained by irradiating a coating film formed from a composition containing only an evaluation target compound as a polymerizable compound and further containing a polymerization initiator with ultraviolet rays having a wavelength of 395 nm under conditions of an irradiation intensity of 1000 mW / cm 2 and a cumulative light amount of 1000 mJ / cm 2 is immersed in tetrahydrofuran, a GPC chart of the tetrahydrofuran solution after the immersion is analyzed, a total peak area of the GPC chart thus obtained is set as a first peak area (S1), and a peak area of a peak derived from a residual component of the evaluation target compound in the GPC chart of the tetrahydrofuran solution is set as a second peak area (S2), and a ratio of the second peak area to the first peak area at this time (S2 / S1) is set as a GPC peak area ratio.

[0015] 〔2〕A cured film formed using the curable composition according to the above-mentioned 〔1〕.

[0016] 〔3〕An organic EL element in which an organic light-emitting layer is sealed using the cured film according to the above-mentioned 〔2〕.

[0017] 〔4〕A method for producing an organic EL element, comprising: a step of applying the curable composition according to the above-mentioned 〔1〕 to a light-emitting layer formation surface of a substrate on which an organic light-emitting layer is formed; and a step of forming a sealing structure by curing the curable composition by irradiation with radiation.

[0018] [Effects of the Invention]

[0019] By the curable composition of the present application, a cured film having less outgassing can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a GPC chart in which a compound represented by Formula (1) is taken as an evaluation target compound.

[0021] Figure 2 is a GPC chart in which a compound represented by Formula (2) is taken as an evaluation target compound. DETAILED DESCRIPTION

[0022] Hereinafter, matters related to the embodiments are described in detail. In addition, in the present specification, a numerical range recited using “~” means that the numerical values recited before and after “~” are included as lower limit values and upper limit values.

[0023] In the present specification, “hydrocarbon group” means a group including a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “chain hydrocarbon group” means a straight-chain hydrocarbon group and a branched-chain hydrocarbon group which are composed of only a chain structure without containing a cyclic structure in the main chain. Among them, the chain hydrocarbon group can be saturated or unsaturated. The “alicyclic hydrocarbon group” means a hydrocarbon group which contains only an alicyclic hydrocarbon structure as a cyclic structure, and does not contain an aromatic ring structure. Among them, the alicyclic hydrocarbon group does not necessarily consist of only an alicyclic hydrocarbon structure, and a group having a chain structure in a part thereof is also included. The “aromatic hydrocarbon group” means a hydrocarbon group which contains an aromatic ring structure as a cyclic structure. Among them, the aromatic hydrocarbon group does not necessarily consist of only an aromatic ring structure, and a chain structure or an alicyclic hydrocarbon structure can be included in a part thereof. In addition, the cyclic structure possessed by the alicyclic hydrocarbon group and the aromatic hydrocarbon group can also have a substituent group including a hydrocarbon structure. The “epoxy group” is a term including “oxiranyl group” and “oxetanyl group”.

[0024] Curable composition

[0025] The curable composition of the present disclosure (hereinafter, also referred to as “the present composition”) contains: a monofunctional oxetane compound (A1); a multifunctional epoxy compound (A2) which is at least one selected from the group consisting of a multifunctional oxetane compound and a multifunctional oxirane compound; and a polymerization initiator. The monofunctional oxetane compound (A1) and the multifunctional epoxy compound (A2) contained in the present composition are polymerizable compounds which are polymerized in the presence of the polymerization initiator, for example, by providing heat or light. Hereinafter, each component contained in the present composition, and other components which are optionally formulated, are described in detail, and the physical properties of the present composition are described. In addition, as for each component, unless specifically mentioned, one kind can be used alone, or two or more kinds can be used in combination.

[0026] [A] Polymerizable compound

[0027] • Monofunctional oxetane compound (A1)

[0028] The monofunctional oxetane compound (A1) is a cationically polymerizable compound having one oxetane ring in one molecule. The monofunctional oxetane compound (A1) included in the present composition is particularly one for which the GPC peak area ratio is 5.0% or less as calculated from the curability evaluation shown below using gel permeation chromatography (GPC).

[0029] Curability evaluation: For a coating film formed from a composition (hereinafter, also referred to as "evaluation composition") containing only an evaluation target compound as a polymerizable compound and further containing a polymerization initiator, ultraviolet rays having a wavelength of 395 nm were irradiated under conditions of an irradiation intensity of 1000 mW / cm 2 and a cumulative light amount of 1000 mJ / cm 2 , thereby obtaining a cured film. The obtained cured film was immersed in tetrahydrofuran (THF), and the THF solution after the immersion was analyzed using GPC, and the total peak area of the GPC chart (also referred to as "cured film GPC chart") thus obtained was set as a first peak area (S1). The peak area of the peak in the cured film GPC chart derived from the residual component of the evaluation target compound was set as a second peak area (S2). The ratio (S2 / S1) of the second peak area (S2) to the first peak area (S1) was set as the GPC peak area ratio, and the curability of the evaluation target compound was evaluated using the GPC peak area ratio.

[0030] Through the curability evaluation, the proportion of the residual component of the evaluation target compound (i.e., unreacted monomer) that has not been polymerized by ultraviolet irradiation among the total amount of the evaluation target compound included in the evaluation composition can be calculated. The smaller the GPC peak area ratio calculated through the curability evaluation, the smaller the amount of unreacted monomer remaining in the cured film after the evaluation composition is irradiated with ultraviolet rays, and it can be said that the curability of the evaluation target compound is good. According to the evaluation method, the reactivity (i.e., curability) of the polymerizable compound can be evaluated by a method that as much as possible conforms to the actual process when a cured film provided on an organic EL element or the like is manufactured using a curable composition.

[0031] The evaluation composition is prepared, for example, by mixing 100 parts by mass of the evaluation target compound, 1 part by mass of the polymerization initiator, and 0.1 part by mass of the surfactant. As the polymerization initiator, a polymerization initiator that can be formulated in the present composition can be appropriately used. In addition, in the evaluation composition, a surfactant can also be contained together with the evaluation target compound and the polymerization initiator in order to improve the coatability of the evaluation composition. As the surfactant as well, a surfactant that can be formulated in the present composition can be appropriately used. From the viewpoint of ensuring the reliability of the evaluation results, the components other than the evaluation target compound among the components formulated in the evaluation composition can be made the same kind and the same amount among the samples to be compared.

[0032] A specific example of the curability evaluation will be described below. First, an evaluation composition containing a monofunctional oxetane compound (A1) as the evaluation target compound, a polymerization initiator, and a surfactant is prepared. Next, the prepared evaluation composition is coated on a glass substrate to form a coating film containing the evaluation composition. Next, the coating film on the glass substrate is irradiated with ultraviolet rays having a wavelength of 395 nm under exposure conditions of an illuminance of 1000 mW / cm 2 and a cumulative light amount of 1000 mJ / cm 2 to cure the evaluation composition. The exposure conditions are an exposure amount sufficient to sufficiently cure the evaluation composition. The curing of the evaluation composition is performed under a nitrogen atmosphere at 25°C and a dew point of -60°C or lower (200 ppm). Next, the cured film obtained by the curing treatment is immersed in THF together with the glass substrate. At this time, the substrate can be immersed in a sufficient amount of THF so that the cured film on the glass substrate is brought into contact with the THF without omission. The immersion time is sufficient to ensure a time for dissolving the cured film formed on the substrate in the THF, for example, 10 minutes to 30 minutes. By analyzing the tetrahydrofuran solution after the immersion by GPC, a GPC chart (cured film GPC chart) is obtained, and the total peak area of the cured film GPC chart is calculated as the first peak area (S1). In addition, it is considered that the tetrahydrofuran solution after the immersion contains unreacted monomers in addition to the polymeric component (i.e., the polymer of the monofunctional oxetane compound (A1)) containing the main component of the cured film on the substrate.

[0033] In addition, unlike the evaluation composition, a monomer solution containing the monofunctional oxetane compound (A1) as the evaluation target compound and THF as a standard sample was prepared, and a GPC chart obtained by GPC analysis of the standard sample (also referred to as "standard GPC chart") was obtained. Based on the standard GPC chart, the peak area of a peak in which the elution time coincided with the peak appearing in the standard GPC chart was set as the second peak area (S2) in the hardened film GPC chart. Furthermore, the peak appearing in the standard GPC chart was a peak derived from the monofunctional oxetane compound (A1) as the evaluation target compound. Moreover, by obtaining the ratio (S2 / S1) of the second peak area (S2) to the first peak area (S1) as the GPC peak area ratio, the hardenability of the monofunctional oxetane compound (A1) was parameterized. The details of the calculation method of the first peak area (S1) and the second peak area (S2) are described in the method described in the Examples described later.

[0034] As specific examples, the results of hardenability evaluation of the compounds represented by the following formula (1) or formula (2) as the evaluation target compound are shown in Figure 1 and Figure 2 .

[0035] [Chemical Formula 1]

[0036]

[0037] Figure 1 and Figure 2 The hardened film GPC chart and the standard GPC chart are shown in one chart each. Figure 1 is the result of using the compound represented by the formula (1) as the evaluation target compound, Figure 2 is the result of using the compound represented by the formula (2) as the evaluation target compound. In Figure 1 and Figure 2 In the charts of

[0038] As Figure 1 and Figure 2In the hardened film GPC chart, the peak is broadened, and a bimodal peak appears at a position (PA in the figure) of elution time (retention time (R.T.)) 16 minutes to 17 minutes. In addition, in the standard GPC chart, a bimodal peak also appears at the position PA of elution time (R.T.) 16 minutes to 17 minutes. Thus, in the hardened film GPC chart, the peak appearing at the position PA can be grasped as a peak of the evaluation target compound origin, and by the ratio of the peak area of the position PA to the total peak area of the hardened film GPC chart (GPC peak area ratio), the unreacted monomer ratio of the evaluation target compound, that is, the hardening property of the evaluation target compound can be grasped. The GPC peak area ratio of each compound is 2.64% for the compound represented by the formula (1) and 8.23% for the compound represented by the formula (2).

[0039] The GPC peak area ratio of the monofunctional oxetane compound (A1) formulated in the present composition, which is sought by the hardening property evaluation, is 5.0% or less. If the GPC peak area ratio exceeds 5.0%, the outgassing amount of the hardened film becomes too much due to the large amount of unreacted monomers remaining in the hardened film. In that case, there is a concern that the organic EL element is deteriorated. From the viewpoint of obtaining a hardened film in which the outgassing amount is sufficiently reduced, the GPC peak area ratio of the monofunctional oxetane compound (A1) is preferably 4.0% or less, more preferably 3.5% or less, and further preferably 3.0% or less. In addition, from the viewpoint of suppressing adverse situations that can occur due to excessively high reactivity, the GPC peak area ratio of the monofunctional oxetane compound (A1) is preferably 0.5% or more, more preferably 1.0% or more, and further preferably 1.5% or more.

[0040] The monofunctional oxetane compound (A1) is not particularly limited in structure as long as the GPC peak area ratio sought by the hardening property evaluation is 5.0% or less. As the monofunctional oxetane compound (A1), a compound having one oxetane ring and one or two substituents bonded to the carbon atom at the 3-position of the oxetane ring can be exemplified. From the aspect that a hardened property composition in which the outgassing amount from the hardened film is small and the wet spreading property is good can be obtained, the monofunctional oxetane compound (A1) can preferably use a compound having one oxetane ring and two substituents (first substituent, second substituent) bonded to the carbon atom at the 3-position of the oxetane ring.

[0041] In terms of the reduction in the amount of outgas from the hardened film and the improvement in the wet spreading property of the curable composition, as the monofunctional oxetane compound (A1), a compound having a methyl group as a substituent (first substituent) bonded to the 3-position of the oxetane ring can be preferably used. It is considered that in the monofunctional oxetane compound (A1), by having a methyl group bonded to the 3-position of the oxetane ring, the reactivity of the monofunctional oxetane compound (A1) is increased due to the reduction in steric hindrance at the time of hardening, for example, as compared with the case where an ethyl group is bonded instead of the methyl group, whereby the unreacted monomer in the hardened film can be reduced. In addition, it is considered that the decomposition of the polymer in the hardened film can be suppressed, as compared with the case where no methyl group is bonded to the 3-position of the oxetane ring, and the wet spreading property of the present composition can be ensured by moderately increasing the interaction with the substrate to which inkjet coating is performed, or the film formed on the substrate.

[0042] In the case where the monofunctional oxetane compound (A1) has the first substituent and the second substituent at the 3-position of the oxetane ring, and the first substituent is a methyl group, as the second substituent, a monovalent group having an alkyl group having a carbon number of 1 to 20, an alkyl group having a carbon number of 2 to 20, and containing -O- between carbon-carbon bonds, or the like can be exemplified. The group exemplified as the second substituent can be linear or branched. In the case where the second substituent is linear, the ease of synthesis can be easily ensured. In addition, in the case where the second substituent is branched, the viscosity of the present composition can be adjusted within a moderate range, and the wet spreading property can be made more excellent. In terms of the moderate ensuring of the viscosity of the present composition, the carbon number of the second substituent is preferably 3 or more, more preferably 4 or more, and further preferably 5 or more. In addition, in order to suppress the viscosity of the present composition from becoming excessively high, the carbon number of the second substituent is preferably 15 or less, and further preferably 12 or less.

[0043] The monofunctional oxetane compound (A1) can have a linear or branched alkyl group having a carbon number of 6 to 20 bonded directly to the oxetane ring, or bonded via 1 -R 1 -O- (wherein, R 1 is an alkanediyl group having a carbon number of 1 to 3, and 1 represents a bond to the oxetane ring). By the monofunctional oxetane compound (A1) having the linear or branched alkyl group, the viscosity of the present composition can be easily adjusted within a moderate range, and the improvement effect of the wet spreading property can be further increased.

[0044] From the viewpoint of further reducing outgassing, the monofunctional oxetane compound (A1) is preferably free of an ether bond in a portion other than the oxetane ring. In the case where the monofunctional oxetane compound (A1) is free of an ether bond in a portion other than the oxetane ring, the effect of reducing outgassing can be further improved as compared to the case where a compound having an ether bond in a portion other than the oxetane ring is used. Furthermore, it is considered that a compound free of an ether bond in a portion other than the oxetane ring is less likely to undergo depolymerization or partial cleavage in a polymer obtained by polymerization of the polymerizable compound containing the monofunctional oxetane compound (A1) after polymerization of the polymerizable compound, which leads to further reduction of outgassing.

[0045] From the viewpoint of ensuring the strength of the hardened film, the molecular weight of the monofunctional oxetane compound (A1) is preferably 100 or greater, more preferably 120 or greater, and still more preferably 140 or greater. In addition, from the viewpoint of improving the wet spreading property of the present composition, the molecular weight of the monofunctional oxetane compound (A1) is preferably 300 or less, more preferably 250 or less, and still more preferably 220 or less.

[0046] As specific examples of the monofunctional oxetane compound (A1), the compounds represented by the following formulas (a-1) to (a-5), respectively, can be given.

[0047] [Chem. 2]

[0048]

[0049] In the present composition, the content of the monofunctional oxetane compound (A1) is preferably 20 to 60 mass% with respect to the total amount of the polymerizable compound contained in the present composition. In the case where the content of the monofunctional oxetane compound (A1) is in the range described above, the amount of outgassing can be sufficiently suppressed while the low dielectric constant of the hardened film obtained by using the present composition is pursued, and the wet spreading property can be made good. From this viewpoint, the content of the monofunctional oxetane compound (A1) is more preferably 25 mass% or greater, and still more preferably 30 mass% or greater, with respect to the total amount of the polymerizable compound. In addition, from the viewpoint of improving the hardenability and the like of the present composition, the content of the monofunctional oxetane compound (A1) is more preferably 55 mass% or less, and still more preferably 50 mass% or less, with respect to the total amount of the polymerizable compound.

[0050] • Polyfunctional epoxy compound (A2)

[0051] The multifunctional epoxy compound (A2) is a compound having at least either one of oxetane rings and oxirane rings in one molecule in a total of two or more. The multifunctional epoxy compound (A2) is not particularly limited as long as it shows cationic polymerizability. From the viewpoint of ensuring good wet spreading property of the present composition, the multifunctional epoxy compound (A2) preferably has a total of two to four, more preferably two, of oxetane rings and oxirane rings in one molecule.

[0052] As the multifunctional epoxy compound (A2), as a multifunctional oxetane compound, 3,7-bis(3-oxetanyl)-5-oxa-nonane, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, bis[l-ethyl(3-oxetanyl)]methyl ether, bis(3-ethyl-3-oxetanylmethyl)ether, ethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, triethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, tetraethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, 1,3-bis(3-ethyl-3-oxetanylmethoxy)propane, 1,4-bis(3-ethyl-3-oxetanylmethoxy)butane, 1,4-bis(3-ethyl-3-oxetanylmethoxymethyl)benzene, 1,3-bis(3-ethyl-3-oxetanylmethoxymethyl)benzene, 1,2-bis(3-ethyl-3-oxetanylmethoxymethyl)benzene, 4,4'-bis(3-ethyl-3-oxetanylmethoxymethyl)diphenyl, 2,2'-bis(3-ethyl-3-oxetanylmethoxymethyl)diphenyl, 1,6-bis((3-methyloxetan-3-yl)methoxy)hexane, 1,6-bis((3-ethyloxetan-3-yl)methoxy)hexane, a hydrolytic condensate of 3-〔(3-ethyloxetan-3-yl)methoxy〕propyl trialkoxysilane, a condensation reaction product of 3-ethyloxetan-3-ylmethanol with a silane tetrol polycondensate, and the like can be mentioned.

[0053] As specific examples of the multifunctional oxirane compound, the following low-molecular compounds containing an epoxy group can be given: 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-m-dioxane, bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexane carboxylate, methylene bis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di(3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylene bis(3,4-epoxycyclohexane carboxylate), (3,4,3',4'-diepoxy) bicyclohexyl, bis(3,4-epoxycyclohexylmethyl) ether, 1,2-epoxy-1,2-bis(3,4-epoxycyclohexane-1-yl)ethane, 1,2-bis(3,4-epoxycyclohexane-1-yl)ethane, 2,2-bis(3,4-epoxycyclohexane-1-yl)propane, and the like.

[0054] Compounds having two or more alicyclic epoxy groups (preferably 3,4-epoxycyclohexyl groups) in the molecule, such as those having trade names of "X-40-2678", "X-40-2670", "X-40-2720" (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.

[0055] Bisphenol A type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol O type epoxy resin, 2,2'-diallyl bisphenol A type epoxy resin, hydrogenated bisphenol type epoxy resin, propylene oxide-added bisphenol A type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, sulfide type epoxy resin, diphenyl ether type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene type epoxy resin, phenol novolak type epoxy resin, o-cresol novolak type epoxy resin, dicyclopentadiene novolak type epoxy resin, biphenyl novolak type epoxy resin, naphthol novolak type epoxy resin, glycidyl amine type epoxy resin, alkyl polyhydric alcohol type epoxy resin, rubber-modified type epoxy resin, glycidyl ester resin, bisphenol A type episulfide resin, and the like epoxy group-containing resins.

[0056] In terms of obtaining a curable composition which, while seeking to obtain a low dielectric constant of the obtained hardened film, exhibits excellent curability, as the multifunctional epoxy compound (A2), a compound having two or more oxetane rings in the molecule or a compound having two or more alicyclic epoxy groups in the molecule can be preferably used in the above.

[0057] In the present composition, the content of the polyfunctional epoxy compound (A2) is preferably 40% by mass or more, more preferably 45% by mass or more, and further preferably 50% by mass or more, relative to the total amount of the polymerizable compounds. In addition, the content of the polyfunctional epoxy compound (A2) is preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less, relative to the total amount of the polymerizable compounds.

[0058] Further, the polyfunctional epoxy compound has high curability, whereas the polyfunctional epoxy compound alone has high viscosity, and in particular, in the case where a cured film is formed by applying the curable composition by inkjet coating, wet spreading is insufficient. Therefore, it is considered that a monofunctional oxetane compound is formulated to improve the wet spreading of the curable composition. However, the monofunctional oxetane compound has a tendency to easily become a cause of outgassing from the cured film. In this regard, the present composition can improve the wet spreading while suppressing outgassing from the cured film by containing a specific compound (monofunctional oxetane compound (A1)) as the monofunctional oxetane compound.

[0059] • Other polymerizable compounds

[0060] The present composition can also contain only the monofunctional oxetane compound (A1) and the polyfunctional epoxy compound (A2) as the polymerizable compounds. In addition, for the purpose of adjusting the curability and the like, a compound (hereinafter, also referred to as "other polymerizable compound") that is different from the monofunctional oxetane compound (A1) and the polyfunctional epoxy compound (A2) can also be contained together with the monofunctional oxetane compound (A1) and the polyfunctional epoxy compound (A2). As the other polymerizable compound, for example, a monofunctional epoxy compound (A3) can be exemplified.

[0061] The monofunctional epoxy compound (A3) is only required to be a compound having one oxirane ring per molecule. As specific examples of the monofunctional epoxy compound (A3), for example, cyclohexene oxide, 1-methyl-1,2-epoxy cyclohexane, 1,2-epoxy-4-vinyl cyclohexane, ethyl glycidyl ether, butyl glycidyl ether, and the like can be exemplified.

[0062] Among them, the monofunctional epoxy compound (A3) easily becomes a cause of outgassing from the cured film. Therefore, the present composition is preferably free of the monofunctional epoxy compound (A3) or contains it in a small amount. Specifically, the content of the monofunctional epoxy compound (A3) is preferably 2% by mass or less, more preferably 1% by mass or less, and further preferably 0.5% by mass or less, relative to the total amount of the polymerizable compounds contained in the present composition.

[0063] <[B] Polymerization initiator>

[0064] The polymerization initiator can be any substance that generates a protic acid or Lewis acid in response to heat or light. Suitable candidates are selected from substances known as thermo-cationic polymerization initiators or photo-cationic polymerization initiators. From the viewpoint of suppressing element deterioration, photo-cationic polymerization initiators are preferred. Examples of photo-cationic polymerization initiators include ionic photoacid-generating and non-ionic photoacid-generating polymerization initiators.

[0065] Examples of photocationic polymerization initiators that generate ionic photoacids include: onium salt compounds, halogen-containing compounds, sulfone compounds, sulfonic acid compounds, sulfonylimide compounds, and diazomethane compounds. Specifically, examples of onium salt compounds include those with an aromatic sulfonium, aromatic monazine, aromatic diazonium, aromatic ammonium, or (2,4-cyclopentadien-1-yl)[(1-methylethyl)benzene]-Fe cation, and an anionic moiety containing BF4. - PF6 - SbF6 - [BX4] - (X is a phenyl group substituted with two or more fluorine or trifluoromethyl groups), or [PRf6] - [Rf is a fluorinated alkyl group] onium salt.

[0066] The onium salt compound described above is preferably used as a polymerization initiator. Preferably, the polymerization initiator contains [PF...] k (C p F 2p+1 ) 6-k ] - The onium fluorinated alkyl fluorophosphates representing the anionic portion (where k is an integer from 3 to 5 and p is an integer from 1 to 3). [PF k (C p F 2p+1 ) 6-k ] - The anion portion represented is due to (C) p F 2p+1 With a value of 1 or higher and the presence of fluorinated carbon chains, it functions as a relatively strong acid. Therefore, its cationic polymerization properties are enhanced, and it is believed that it can lead to superior curing properties.

[0067] The cationic portion of onium fluorinated alkyl fluorophosphates is not particularly limited. Specific examples of the cationic portion include, for instance, the sulfonium cation represented by formula (4) or formula (5) below.

[0068] [Chemistry 3]

[0069]

[0070] (In formula (4) and formula (5), R 11 ~R 16 independently a hydrogen atom, an alkyl group having a carbon number of 1 to 6, an alkoxy group having a carbon number of 1 to 6, an alkylthio group having a carbon number of 1 to 6, an alkylcarbonyloxy group having a carbon number of 1 to 6, an alkylcarbonylthio group having a carbon number of 1 to 6, an alkoxycarbonyloxy group having a carbon number of 1 to 6, or a phenyl group. r1 and r2 are independently 0 or 1)

[0071] (In formula (4) and formula (5), R 11 ~R 16 is preferably a hydrogen atom, an alkyl group having a carbon number of 1 to 5, a methoxy group, a methylthio group, a methylcarbonyloxy group, a methylcarbonylthio group, a methoxycarbonyloxy group, or a phenyl group, and more preferably a hydrogen atom.

[0072] As a specific example of the ionic photoacid-generating type photocationic polymerization initiator, as the onium salt of the cationic portion represented by formula (4) or formula (5) and the anion portion represented by [PF k (C p F 2p+1 ) 6-k ] - As the specific example of the onium salt of the anion portion represented by formula (4) and formula (5), cationic polymerization initiators described in Japanese Patent Application Publication No. 2018-36533, and products with trade names of "CPI-210S", "CPI-410S" (both manufactured by San-apro Co., Ltd.), and the like can be given.

[0073] As the non-ionic photoacid-generating type photocationic polymerization initiator, for example, nitrobenzyl ester, sulfonic acid derivative, phosphate ester, phenol sulfonic acid ester, diazo naphthoquinone, N-hydroxy imide sulfonic acid ester, oxime ester carboxylic acid ester, and the like can be given.

[0074] In the present composition, the content of the polymerization initiator is usually 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the present composition. The content of the polymerization initiator is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less with respect to 100 parts by mass of the total amount of the polymerizable compounds. By setting the content of the polymerization initiator to the above range, the curability of the present composition is good, and in addition, a hardened film having high transparency can be obtained.

[0075] <Other Components>

[0076] The present composition can further contain components other than the polymerizable compounds and the polymerization initiator (hereinafter, also referred to as "other components") on the basis of containing the polymerizable compounds and the polymerization initiator. As the other components, for example, a polymerization inhibitor, an antioxidant, a surfactant, and the like can be given.

[0077] Polymerization inhibitor / antioxidant

[0078] The present composition can also contain at least one compound selected from the group consisting of polymerization inhibitors and antioxidants (hereinafter, also referred to as "compound (C)"). By the present composition further containing the compound (C), the storage stability of the present composition can be improved.

[0079] As the polymerization inhibitor, there is no particular limitation, and for example, hydroquinone, p-methoxyphenol, p-benzoquinone, naphthoquinone, phenanthraquinone, toluquinone, 2,5-diacetoxy-p-benzoquinone, 2,5-dihexanoyloxy-p-benzoquinone, 2,5-acetoxy-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-p-cresol hydroquinone monomethyl ether, phenothiazine, a-naphthol, acetylformamide acetate, acetylformamide sulfate, phenylhydrazine hydrochloride, hydrazine hydrochloride, trimethylbenzylammonium chloride, laurylpyridinium chloride, cetyltrimethylammonium chloride, phenyltrimethylammonium chloride, trimethylbenzylammonium oxalate, bis(trimethylbenzylammonium) oxalate, trimethylbenzylammonium maleate, trimethylbenzylammonium tartrate, trimethylbenzylammonium glycolate, phenyl-β-naphthylamine, p-benzylaminophenol, di-β-naphthyl-p-phenylenediamine, dinitrobenzene, trinitrotoluene, picric acid, cyclohexanone oxime, pyrogallol, tannic acid, resorcinol, triethylamine hydrochloride, dimethylamine hydrochloride, and dibutylamine hydrochloride, and the like can be exemplified.

[0080] In the case where a polymerization inhibitor is formulated in the present composition, the content of the polymerization inhibitor is preferably 0.01 parts by mass to 10 parts by mass, more preferably 0.01 parts by mass to 5 parts by mass, and further preferably 0.01 parts by mass to 3 parts by mass, with respect to 100 parts by mass of the total amount of the polymerizable compound contained in the present composition. By being in the range, the viscosity increase due to unnecessary thermal energy, or the occurrence of gelling or hardening reactions can be inhibited, and at the same time, the viscosity of the present composition can be kept within a moderate range even after a long period of circulation or storage, and good wet-spreading properties (and further, inkjet coatability) can be ensured.

[0081] The antioxidant serves to improve the storage stability of the present composition by preventing oxidative deterioration of the hardening composition. As the antioxidant, for example, phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like can be exemplified.

[0082] As the phenol-based antioxidant, for example, monophenols such as 2,6-di-tert-butyl- p-cresol, butylated hydroxyltoluene, 2,6-di-tert-butyl-p-ethylphenol, and stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; bisphenols such as 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), and 3,9-bis[1,1-dimethyl-2-{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane; and high molecular weight phenols such as 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetra-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), bis[3,3'-bis-(4'-hydroxy-3'-tert-butylphenyl)butanoic acid]diol ester, 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol can be exemplified.

[0083] As the sulfur-based antioxidant, for example, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate can be exemplified.

[0084] As the phosphorus-based antioxidant, for example, diphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis(octadecyl) phosphite, cyclic neopentanetetraylbis(2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis(2,4-di-tert-butyl-6-methylphenyl) phosphite, and bis[2-tert-butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl]hydrophosphite can be exemplified.

[0085] The antioxidant can be used alone, respectively, and two or more antioxidants can be used in combination, for example, a phenol-based / sulfur-based antioxidant or a phenol-based / phosphorus-based antioxidant. In addition, a commercially available phenol-based antioxidant (for example, IRGANOX 1010 (trade name) manufactured by BASF Japan) or a commercially available phosphorus-based antioxidant (for example, IRGAFOS 168 (trade name) manufactured by BASF Japan) can be used alone, respectively, or these can be used in combination.

[0086] In the case where an antioxidant is formulated in the present composition, the content of the antioxidant is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and further preferably 0.01 to 3 parts by mass, relative to 100 parts by mass of the total amount of the polymerizable compound contained in the present composition. By being in the range, the viscosity increase due to unnecessary heat energy or the occurrence of gelling or hardening reactions can be suppressed, and at the same time, the viscosity of the present composition can be kept in a moderate range even after a long period of circulation or storage, and good wet spreading properties (and further, inkjet coatability) can be ensured.

[0087] In addition, in order to improve the storage stability of the present composition, in addition to containing the compound (C), a methylene quinone or a heat stabilizer such as 2-dimethylaminomethyl alcohol described in Japanese Patent Laid-Open No. 2020-518952 can be contained in the present composition.

[0088] • Surfactant

[0089] The surfactant can be used to further improve the coatability (particularly, wet spreading properties or reduction of coating unevenness) of the present composition. As the surfactant, for example, a fluorine-based surfactant (including a fluorine-containing nonionic surfactant), a silicone-based surfactant, or a nonionic surfactant can be exemplified.

[0090] As specific examples of the surfactant, as the fluorine-based surfactant, Megafac F-171, Megafac F-172, Megafac F-173, Megafac F-251, Megafac F-430, Megafac F-554, Megafac F-563 (manufactured by DIC Corporation); Fluorad FC430, Fluorad FC431 (manufactured by Sumitomo 3M Company); Asahi Guard AG710, Surflon S-382, Surflon SC-101, Surflon SC-102, Surflon SC-103, Surflon SC-104, Surflon SC-105, Surflon SC-106, Surflon S-611 (manufactured by AGC Seimi Chemical Company); Polyflow No. 75, Polyflow No. 95 (manufactured by Kyoeisha Chemical Company); FTX-218 (manufactured by NEOS Corporation); Eftop EF301, Eftop EF303, Eftop EF352 (manufactured by Shin-Etsu Chemical Company), and the like can be listed by the trade names.

[0091] As the silicone-based surfactant, SH200-100cs, SH28PA, SH30PA, SH89PA, SH190, SH8400, SH193, SZ6032, SF8428, DC57, DC190, PAINTAD 19, FZ-2101, FZ-77, FZ-2118, L-7001, L-7002 (manufactured by Toray Dow Corning Company); organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Company); BYK-300, BYK-306, BYK-310, BYK-330, BYK-335, BYK-341, BYK-344, BYK-370, BYK-340, BYK-345 (manufactured by BYK-Chemie Japan Company) can be listed by the trade names.

[0092] As the nonionic surfactant, for example, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, and the like can be exemplified.

[0093] In the case where a surfactant is formulated in the present composition, the content of the surfactant is preferably 0.01 parts by mass or more and 3 parts by mass or less, more preferably 0.02 parts by mass or more and 2 parts by mass or less, and further preferably 0.1 parts by mass or more and 1.0 parts by mass or less, with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the present composition.

[0094] As other components, in addition to the aforementioned components, for example, a sensitizer, a softener, a plasticizer, an adhesion aid, an organic solvent, and the like can be exemplified. The formulation ratio of these components can be appropriately selected depending on each component within a range not impairing the effects of the present disclosure.

[0095] An organic solvent can also be formulated in the present composition for the purpose of dissolving each component formulated in the present composition, and the like. On the other hand, from the viewpoint of being able to form a hardened film (particularly, an organic sealing layer for protecting an organic light-emitting layer of an organic EL element) without performing a heating treatment, it is preferable to minimize the amount of use of the organic solvent. Specifically, the content of the organic solvent in the present composition is preferably 0% by mass or more and 3% by mass or less, more preferably 0% by mass or more and 2% by mass or less, and particularly preferably substantially does not contain. Here, in the present specification, the "substantially does not contain an organic solvent" means that the amount of the organic solvent contained in the present composition is 1% by mass or less, and preferably 0.5% by mass or less.

[0096] In the case where an organic solvent is formulated in the present composition, as the organic solvent used, an organic solvent that can dissolve or disperse each component formulated in the present composition and does not react with each component can be preferably used. Specifically, alcohols, ketones, esters, ethers, aromatic hydrocarbons, amides can be exemplified.

[0097] As the alcohols, methanol, ethanol, isopropanol, butanol, octanol, and the like can be exemplified. As the ketones, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and the like can be exemplified. As the esters, ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, methyl-3-methoxypropionate, and the like can be exemplified. As the ethers, polyoxyethylene lauryl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol methyl ethyl ether, and the like can be exemplified. As the aromatic hydrocarbons, benzene, toluene, xylene, and the like can be exemplified. As the amides, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like can be exemplified.

[0098] Preparation of the curable composition

[0099] The present composition can be prepared by mixing the polymerizable compound and the polymerization initiator, and other components as necessary. From the viewpoint of producing a curable composition with good workability, or from the viewpoint of forming a hardening film with high sealing effect, the content of the polymerizable compound in the present composition is preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and further preferably 90 parts by mass or more, relative to 100 parts by mass of the total amount of the present composition.

[0100] Viscosity of the curable composition

[0101] The viscosity of the present composition, measured using an E-type viscometer under conditions of 25°C and 20 rpm, is preferably in the range of 1.0 mPa-s to 40.0 mPa-s. If the viscosity of the present composition is 40.0 mPa-s or less, the wet spreading becomes better when the present composition is applied to a substrate by inkjet coating, and uneven application caused by recesses and the like can be inhibited. In addition, if the viscosity of the present composition is 1.0 mPa-s or more, the film thickness can be sufficiently ensured when the present composition is applied to a substrate, and an organic sealing layer that sufficiently exhibits a sealing effect can be formed. The present composition is preferably a curable composition for inkjet coating.

[0102] From the viewpoint of obtaining a curable composition with excellent inkjet coating properties, the viscosity of the present composition is more preferably 30.0 mPa-s or less, and further preferably 20.0 mPa-s or less, and particularly preferably 10.0 mPa-s or less. In addition, from the viewpoint of stably performing ejection using inkjet and sufficiently ensuring the film thickness, the viscosity of the present composition is more preferably 2.0 mPa-s or more, and further preferably 5.0 mPa-s or more. In the present specification, the viscosity of the curable composition is a value measured in accordance with Japanese Industrial Standards (JIS) K2283.

[0103] Wet spreading

[0104] The present composition has good wet spreading when applied to a substrate. Specifically, for an evaluation substrate obtained by forming SiNx on a glass substrate, an inkjet head including 20 nozzles arranged in a column in a direction orthogonal to the scanning direction was used, inkjet ejection was performed at a pitch of 50 pm x 50 pm, a line pattern with a width of 1000 pm was drawn, and after standing for 3 minutes, the wet spreading was evaluated by measuring the width of the line pattern using a laser microscope (VK-X2000, manufactured by Keyence Corporation) at an illuminance of 1000 mW / cm 2 and the cumulative light quantity was 1000 mJ / cm 2under the conditions of 25°C, a nitrogen atmosphere, and a dew point of -60°C or lower (200 ppm). The line pattern width is measured after the line pattern is exposed to ultraviolet light of a wavelength of 395 nm under the conditions of 25°C, a nitrogen atmosphere, and a dew point of -60°C or lower (200 ppm) to harden the line pattern, and the line pattern width is 1500 μm or greater. This composition is particularly suitable as a hardening composition for inkjet coating. In addition, the line pattern width measured in the evaluation of wet spread is a measured value when the hardening of the hardening composition is performed under the conditions of 25°C, a nitrogen atmosphere, and a dew point of -60°C or lower (200 ppm).

[0105] <Amount of outgassing of hardened film>

[0106] The hardening film in the present composition at 110°C is a film obtained by irradiating a coating film formed from the hardening composition with ultraviolet light of a wavelength of 395 nm under the conditions of an irradiance of 1000 mW / cm 2 and a cumulative light amount of 1000 mJ / cm 2 When the hardening film is heated, the amount of outgassing detected by the headspace method is 400 ppm or less, preferably 250 ppm or less. Here, the outgassing from the hardening film mainly includes components derived from unreacted monomers (particularly monofunctional monomers) in the polymerizable compound contained in the hardening composition that are not reacted when the hardening film is formed, and components derived from decomposition products produced by depolymerization or partial cleavage caused by acid components remaining in the film after polymerization. The monofunctional oxetane compound (Al) contained in the present composition has high reactivity caused by radiation, and is less likely to decompose, so it is believed that a low amount of outgassing can be achieved. In addition, the present composition, which can form a hardening film having a sufficiently low amount of outgassing, is preferably used as a hardening film material for an organic EL element. Furthermore, the measurement method for the amount of outgassing of the hardening film is described in detail in accordance with the method described in the Examples below.

[0107] <Dielectric constant of hardened film>

[0108] A hardening film having a sufficiently low dielectric constant can be obtained by hardening the present composition. Specifically, a hardening film having a dielectric constant of 3.0 or less can be obtained by irradiating a coating film formed from the hardening composition with ultraviolet light of a wavelength of 395 nm under the conditions of an irradiance of 1000 mW / cm 2 and a cumulative light amount of 3000 mJ / cm 2The dielectric constant of the hardened film obtained by irradiating the present composition with ultraviolet light of a wavelength of 395 nm under the above conditions is preferably 2.8 or less at a frequency of 100 kHz. The dielectric constant of the hardened film obtained by the above conditions is more preferably 2.7 or less, and further preferably 2.6 or less. For example, in an organic EL light-emitting device using a touch panel method, a touch sensor is arranged on a substrate, but in the case where the dielectric constant of the sealing structure is high, there is a concern that malfunctions and the like will occur when the touch panel is used. Therefore, it is required that the sealing structure provided on the organic EL element have a low dielectric constant. In this regard, according to the present composition, a hardened film having a sufficiently low dielectric constant can be obtained. In addition, the details of the measurement method of the dielectric constant of the hardened film are in accordance with the method described in the Examples described later.

[0109] Hardened film and organic EL element

[0110] The hardened film of the present disclosure (hereinafter, also referred to as "the present hardened film") is formed from the curable composition prepared as described above. The present composition can obtain a hardened film having good wet spreading properties, a small amount of outgassing, and a low dielectric constant. Such a present composition can be used, for example, as a sealing structure of an organic EL element, a microlens, an anti-reflection film, a diffraction grating of an Augmented Reality (AR) element, and the like. In addition, the present composition can also be used as a hole-filling material for a hole such as an HID (Hole In a Display area) structure or a material for forming a planarization film.

[0111] Further, according to the present composition, the moisture permeability is low, the intrusion of foreign matter can be prevented, and a hardened film having excellent bending resistance can be formed, and thus the present composition can also be used as a material for forming a coating layer for protecting a wiring in a bending portion of a flexible display or a bending excess length portion in which a wiring extending from a display portion to the outside is provided. As the coating layer of the bending portion, for example, a MICRO-COATING LAYER described in International Publication No. 2016 / 09925 can be cited. The formation of the MICRO-COATING LAYER can be performed by slit coating, and can also be performed by inkjet coating. The present composition is useful in that it can cope with any of these coating methods. The present composition is particularly useful as a sealing structure forming composition for thin film sealing (TFE: Thin Film Encapsulation) of an organic electroluminescent element (organic EL element) and thereby forming a sealing structure.

[0112] The present hardened film and an organic EL element in which an organic light-emitting layer is sealed with the present hardened film can be manufactured using the present composition by a method including Process 1 and Process 2 described below.

[0113] (Step 1) a step of applying the present composition to a light-emitting layer formation surface of a substrate on which an organic light-emitting layer is formed

[0114] (Step 2) a step of forming a sealing structure by hardening the present composition by irradiation of a radiation

[0115] Hereinafter, each step will be described in detail.

[0116] [Step 1: Application Step]

[0117] In this step, a coated film containing the present composition is formed on the light-emitting layer formation surface by applying the present composition to the light-emitting layer formation surface of a substrate on which an organic light-emitting layer is formed. On the substrate on which the present composition is applied, a laminate including various layers such as an anode layer, a hole injection layer, a hole transport layer, an electron injection layer, a cathode layer, and the like in addition to the organic light-emitting layer is formed, and an organic EL element is constituted from the laminate. The light-emitting layer formation surface on which the present composition is applied can be covered with an inorganic film (inorganic sealing layer). As an inorganic material constituting the inorganic film, for example, silicon nitride (SiNx) or silicon oxide (SiOx) or the like can be exemplified. In this case, a thin film sealing layer containing an organic sealing layer and an inorganic sealing layer is formed on the organic light-emitting layer as a sealing structure.

[0118] As a method of applying the present composition, for example, a spray method, a roll coating method, a spin coating method, a slit die coating method, a bar coating method, an inkjet coating method, or the like can be exemplified. From the aspects of yield and thin film formation, the inkjet coating method among these can be preferably applied. The present composition is low in viscosity and exhibits excellent hardenability, and generation of application unevenness is suppressed, and thus can be preferably used for inkjet coating.

[0119] [Step 2: Hardening Step]

[0120] In this step, a hardened film is obtained by irradiating a radiation to the coated film formed in the Step 1 and hardening the coated film. As the radiation, for example, ultraviolet rays, far ultraviolet rays, visible rays, X-rays, an electron beam, or the like can be exemplified. Among these, ultraviolet rays are preferable, and for example, ultraviolet rays having a wavelength of 350 nm to 400 nm can be preferably used as the irradiation light. As the exposure amount of the radiation, 0.05 J / m 2 ~ 10 J / m 2 are preferable. Thereby, an organic EL element covered with an organic sealing layer containing the present composition can be obtained. The thickness of the hardened film is usually 0.5 μm to 15 μm. The organic sealing layer formed from the present composition can be further covered with an inorganic film. As an inorganic material constituting the inorganic film, for example, silicon nitride (SiNx) or silicon oxide (SiOx) or the like can be exemplified.

[0121] The organic EL element of the present disclosure manufactured by the method including the above-described process 1 and process 2 seals the organic light-emitting layer with the organic sealing layer containing the present composition. Therefore, in the organic EL element of the present disclosure, the case where moisture penetrates into the organic light-emitting layer can be sufficiently suppressed, and thus the adverse situations caused by moisture can be suppressed, specifically, the generation of dark spots or the reduction of the light-emitting properties such as luminance and luminous efficiency can be suppressed. In addition, in the organic EL element of the present disclosure, the generation of outgassing from the organic sealing layer is less, and further, the dielectric constant of the organic sealing layer is sufficiently low. Such an organic EL element of the present disclosure is useful, for example, as an organic EL lighting device or an organic EL display device.

[0122] The present disclosure described in detail above includes the following examples.

[0123] [Example 1] A curable composition containing: a monofunctional oxetane compound (A1); a multifunctional epoxy compound (A2) which is at least one selected from the group consisting of a multifunctional oxetane compound and a multifunctional oxirane compound; and a polymerization initiator, wherein the curable composition has a GPC peak area ratio of 5.0% or less, which is calculated by the curability evaluation shown below using gel permeation chromatography (GPC), and a hardened film obtained by irradiating a coating film formed from the curable composition with ultraviolet rays having a wavelength of 395 nm under conditions of an irradiation intensity of 1000 mW / cm 2 and a cumulative light amount of 1000 mJ / cm 2 exhibits an outgassing amount of 400 ppm or less detected by a headspace method when heated.

[0124] Curability evaluation: A hardened film obtained by irradiating a coating film formed from a composition containing only an evaluation target compound as a polymerizable compound and further containing a polymerization initiator with ultraviolet rays having a wavelength of 395 nm under conditions of an irradiation intensity of 1000 mW / cm 2 and a cumulative light amount of 1000 mJ / cm 2 is immersed in tetrahydrofuran, the tetrahydrofuran solution after the immersion is analyzed by GPC, the total peak area of the GPC chart thus obtained is set as a first peak area (S1), and the peak area of the peak derived from the residual components of the evaluation target compound in the GPC chart of the tetrahydrofuran solution is set as a second peak area (S2), and the ratio of the second peak area to the first peak area at this time (S2 / S1) is set as a GPC peak area ratio.

[0125] 〔Example 2〕 The curable composition according to any one of 〔Example 1〕, wherein for an evaluation substrate obtained by film formation on a glass substrate using SiNx, an inkjet head including 20 nozzles arranged in a row in a direction orthogonal to a scanning direction is used, inkjet ejection is performed at a pitch of 50 μm x 50 μm, a line pattern having a width of 1000 μm is drawn, after standing for 3 minutes, the line pattern is exposed to ultraviolet rays having a wavelength of 395 nm under conditions that the illuminance is 1000 mW / cm 2 and the cumulative light amount is 1000 mJ / cm 2 , and is hardened, and the line pattern width at this time is 1500 μm or more.

[0126] 〔Example 3〕 The curable composition according to any one of 〔Example 1〕 or 〔Example 2〕, wherein the viscosity at 25°C is 1.0 mPa-s to 40.0 mPa-s.

[0127] 〔Example 4〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 3〕, wherein the monofunctional oxetane compound (A1) has two substituents at the 3-position of the oxetane ring.

[0128] 〔Example 5〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 4〕, wherein the monofunctional oxetane compound (A1) has a methyl group bonded to the 3-position of the oxetane ring.

[0129] 〔Example 6〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 5〕, wherein the monofunctional oxetane compound (A1) has no ether bond in a portion other than the oxetane ring.

[0130] 〔Example 7〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 6〕, wherein the monofunctional oxetane compound (A1) has a linear or branched alkyl group having 6 to 20 carbons bonded directly to the oxetane ring or via 1 -R 1 -O- (wherein, R 1 is an alkanediyl group having 1 to 3 carbons, and 1 represents a bond to the oxetane ring).

[0131] 〔Example 8〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 7〕, wherein the content of the monofunctional oxetane compound (A1) is 20 mass% to 60 mass% relative to the total amount of the polymerizable compound contained in the curable composition.

[0132] 〔Example 9〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 8〕, wherein a dielectric constant at a frequency of 100 kHz of a hardened film obtained by irradiating the curable composition with ultraviolet rays having a wavelength of 395 nm under conditions of an illuminance of 1000 mW / cm 2 and a cumulative light amount of 3000 mJ / cm 2 is 2.8 or less.

[0133] 〔Example 10〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 9〕, for inkjet coating.

[0134] 〔Example 11〕 The curable composition according to any one of 〔Example 1〕 to 〔Example 10〕, for forming a sealing structure that seals an organic light-emitting layer of an organic EL element.

[0135] 〔Example 12〕 A hardened film formed using the curable composition according to any one of 〔Example 1〕 to 〔Example 11〕.

[0136] 〔Example 13〕 An organic EL element in which an organic light-emitting layer is sealed with the hardened film according to 〔Example 12〕.

[0137] 〔Example 14〕 A method for manufacturing an organic EL element, including: a step of coating the curable composition according to any one of 〔Example 1〕 to 〔Example 11〕 on a light-emitting layer formation surface of a substrate on which an organic light-emitting layer is formed; and a step of forming a sealing structure by hardening the curable composition by irradiation with radiation.

[0138] 〔Example 15〕 The method for manufacturing an organic EL element according to 〔Example 14〕, wherein the curable composition is coated by inkjet coating.

[0139] [Example]

[0140] Hereinafter, the present application will be specifically described by Examples, but the present application is not limited to the following Examples. Furthermore, "parts" and "%" in Examples and Comparative Examples are mass-based unless otherwise specified.

[0141] 1. Synthesis of compounds and evaluation of curability

[0142] [Synthesis Example 1] Synthesis of oxetane 1

[0143] To a 500 mL four-necked flask equipped with a thermometer, a dropping funnel, and a Dimroth cooling tube, 113 g of a 20% sodium ethoxide ethanol solution, 50.9 mL of ethanol were added, and diethyl methylmalonate 54.6 g was added dropwise over 40 minutes while stirring at an internal temperature of 40°C to 50°C under a nitrogen atmosphere, and stirring was performed at an internal temperature of 50°C for 30 minutes. Subsequently, 1-bromononane 101 g was added dropwise over 10 minutes at the same temperature, and stirring was performed under reflux conditions for 3 hours. After cooling to room temperature, insoluble matter was filtered by passing through celite, and the obtained solution was concentrated under reduced pressure using a rotary evaporator, and ethanol was distilled off. After separating into layers by adding ethyl acetate about 1000 mL and ion exchange water 800 mL to the residue, the organic layer was dried using anhydrous magnesium sulfate, and concentrated under reduced pressure using a rotary evaporator. The obtained residue was dried under reduced pressure, thereby obtaining 129 g of a crude product of compound (1a).

[0144] [Chem. 4]

[0145]

[0146] To a 2 L four-necked flask equipped with a stirring rod, a thermometer, a dropping funnel, and a Dimroth cooling tube and subjected to nitrogen substitution, lithium aluminum hydride 19.1 g, anhydrous tetrahydrofuran (THF) 192 mL were added, and cooling was performed to an internal temperature of 10°C or lower under a nitrogen atmosphere. Subsequently, a solution in which the crude product of compound (1a) 129 g was dissolved in anhydrous tetrahydrofuran (THF) 1343 mL was added over 20 minutes or more in such a manner that the reaction does not become violent, and stirring was performed under reflux conditions for 1 hour. After confirming the completion of the reaction by thin layer chromatography (TLC), cooling was performed to an internal temperature of 10°C or lower. To the four-necked flask in which the reaction mixture was placed, a stirring wing and a three one motor were attached, and saturated sodium sulfate aqueous solution was added carefully until the reaction mixture changed from gray to white, and excess lithium aluminum hydride was decomposed, and the reaction was stopped. Insoluble matter was filtered using celite, and the obtained solution was concentrated under reduced pressure using a rotary evaporator, and THF was distilled off. The residue was dissolved in ethyl acetate, and washed sequentially with 1M-HCl, saturated NaHCO3 aqueous solution, ion exchange water, and the organic layer was concentrated under reduced pressure using a rotary evaporator. The obtained residue was purified using a silica gel column to obtain 59.5 g of compound (1b).

[0147] [Chem. 5]

[0148]

[0149] To a 2L four-necked flask equipped with a stirring blade, a San-Yo motor, a thermometer, and a dropping funnel, and subjected to nitrogen substitution, 59.5g of compound (1b) and 168mL of anhydrous THF were added, and cooled to an internal temperature of 10°C or lower under a nitrogen atmosphere. Then, 136mL of a 1.6M butyllithium hexane solution was added dropwise to the four-necked flask over 90 minutes so that the internal temperature would not exceed 10°C, and then stirred at room temperature for 1 hour. Thereafter, after the reaction mixture was cooled to an internal temperature of 10°C or lower, a solution in which 37.7g of tosyl chloride was dissolved in 567mL of anhydrous THF was added dropwise over 15 minutes, and then stirred at room temperature for 90 minutes. Thereafter, the reaction mixture was cooled to an internal temperature of 10°C or lower, 136mL of a 1.6M butyllithium hexane solution was added dropwise over 15 minutes so that the internal temperature would not exceed 10°C, and then stirred at room temperature overnight. Then, after stirring at an internal temperature of 55°C for 3 hours, the reaction was stopped by adding methanol. The insoluble matter was filtered using diatomite to obtain a solution, and the obtained solution was concentrated under reduced pressure using a rotary evaporator, and THF and hexane were distilled off. The residue was dissolved in ethyl acetate, washed with ion-exchange water, and then the organic layer was concentrated under reduced pressure using a rotary evaporator. The obtained residue was purified using a silica gel column to obtain 37.7g of an oxetane represented by the following formula.

[0150] [Chemical 6]

[0151]

[0152] Evaluation of hardness

[0153] A composition for monomer hardness evaluation (hereinafter, also referred to simply as “evaluation composition”) was prepared by mixing 100 parts by mass of the oxetane 1, 1 part by mass of the photocationic polymerization initiator represented by Chemical Formula (I2-1) described in paragraph 0127 of Japanese Patent Application Publication No. 2018-036533, and 0.1 part by mass of a fluorine-containing nonionic surfactant (“F554” manufactured by DIC Corporation) under an air atmosphere.

[0154] Then, the evaluation composition was applied to an alkali-free glass substrate using a spin coater so that the thickness after hardening would be 8μm under a nitrogen atmosphere at 25°C and a dew point of -60°C (200ppm) or lower. After the evaluation composition was applied, an LED UV lamp was used to irradiate the evaluation composition under the same conditions as at the time of application, at an illuminance of 1000mW / cm 2 , and a cumulative light amount of 1000mJ / cm 2The evaluation composition was irradiated with 395 nm ultraviolet rays under the same exposure conditions as in the above-described Example 1, and the evaluation composition was hardened. As the LED UV lamp, UniJet E110Z HD (Model U395A-455, manufactured by USHIO Inc.) was used. Thereafter, the hardened film was immersed in THF together with the substrate for a time sufficient to dissolve the hardened film in THF, and a hardened film dissolution solution was obtained. At the time of immersing the hardened film, the substrate on which the hardened film was formed was immersed in THF as a whole.

[0155] In contrast to the above, a compound of the same kind as the monomer used in the preparation of the evaluation composition was dissolved in THF, and this was used as a monomer dissolution solution. The molecular weight distribution of the obtained hardened film dissolution solution and the monomer dissolution solution was measured by GPC. The GPC device used was "HLC-8320 GPC" (manufactured by Tosoh-Techno System). The area ratio (peak area ratio) of the area in the peak in the GPC chart of the hardened film dissolution solution (hardened film GPC chart) to the total peak area, which coincided with the GPC chart of the monomer dissolution solution (standard GPC chart), was calculated, and the result was 2.38%.

[0156] [Synthesis Example 2] Synthesis of oxetane 2

[0157] To a 1 L four-necked flask into which a stirrer bar was placed and which was equipped with a thermometer, a dropping funnel, and a Dimroth cooling tube and was subjected to argon substitution, 3-methyl-3-oxetanemethanol 11.0 g and anhydrous tetrahydrofuran 150 mL were added, and under argon atmosphere, 48 mL of n-butyllithium was added dropwise under stirring at an internal temperature of 5°C, and stirring was performed for 1 hour. Subsequently, a substance obtained by dissolving p-toluenesulfonyl chloride 22.6 g in anhydrous tetrahydrofuran 100 mL was added dropwise under stirring, and stirring was performed for 1 hour. A small amount of the reaction solution was added to ice water 300 g, and the reaction was stopped. After extraction was performed with dichloromethane, the organic layer was dried over magnesium sulfate and concentrated, and a crude product 29.53 g of compound (2a) was obtained. In the formula, "Ts" represents a p-toluenesulfonyl group.

[0158] [Formula 7]

[0159]

[0160] To a 1 L four-necked flask equipped with a stirrer, a thermometer, a dropping funnel and a Dimroth cooling tube, and subjected to argon substitution, was added 150 mL of anhydrous dimethyl sulfoxide, and under argon atmosphere, 4.43 g of sodium hydride was added dropwise at an internal temperature of 20°C under stirring for 30 minutes. Then, a substance obtained by dissolving 14.4 g of 2-ethyl-l-hexanol in 40 mL of anhydrous dimethyl sulfoxide was added dropwise under stirring for 1 hour. A substance obtained by dissolving 25.81 g of compound (2a) in 40 mL of anhydrous dimethyl sulfoxide was added dropwise under stirring for 1 hour. The reaction was stopped by adding a small amount of the reaction solution to 500 g of ice water successively. After extraction with isopropyl ether, the organic layer was dried over magnesium sulfate and concentrated. The obtained crude product was distilled at 82°C under 0.3 kPa, and subjected to column chromatography on silica gel to obtain an oxetane represented by the following formula.

[0161] [Chem. 8]

[0162]

[0163] • Evaluation of the Hardening Property

[0164] An evaluation composition was prepared in the same manner as in Synthesis Example 1, except that oxetane 2 was used instead of oxetane 1, and the hardening property of oxetane 2 was evaluated by GPC measurement. The GPC peak area ratio was calculated from the GPC chart of the hardened film, and the result was 2.64% (GPC peak area ratio of the low molecular weight component). Figure 1

[0165] [Comparative Synthesis Example 1] Synthesis of Oxetane 3

[0166] In Synthesis Example 1, diethyl methylmalonate was used instead of diethyl ethylmalonate, and l-bromo-3-ethylheptane was used instead of l-bromononane, and otherwise, oxetane 3 represented by the following formula was obtained in the same manner as in Synthesis Example 1 in an amount of 48.2 g.

[0167] [Chem. 9]

[0168]

[0169] • Evaluation of the Hardening Property

[0170] An evaluation composition was prepared in the same manner as in Synthesis Example 1, except that oxetane 3 was used instead of oxetane 1, and the hardening property of oxetane 3 was evaluated. The GPC peak area ratio was calculated in the same manner as in Synthesis Example 1, and the result was 5.66% (GPC peak area ratio of the low molecular weight component).

[0171] [Comparative Synthesis Example 2] Synthesis of Oxetane 4

[0172] ​In Synthesis Example 1, diethyl methylmalonate was used instead of diethyl malonate, 1-bromododecane was used instead of 1-bromononane, and otherwise the same procedure as in Synthesis Example 1 was followed to obtain 37.6 g of the oxetane 4 represented by the following formula.

[0173] [Chem. 10]

[0174]

[0175] • Evaluation of the curability

[0176] An evaluation composition was prepared in the same manner as in Synthesis Example 1, using oxetane 4 instead of oxetane 1, and the curability of oxetane 4 was evaluated. The GPC peak area ratio was calculated in the same manner as in Synthesis Example 1, and the result was 1.39%.

[0177] 2. Preparation of the curability composition

[0178] The components used in the preparation of the curability composition were as follows.

[0179] 〈Polymerizable compound〉

[0180] • Monofunctional oxetane compound

[0181] A1-1: Oxetane 1 obtained by Synthesis Example 1 (GPC peak area ratio: 2.38%)

[0182] A1-2: Oxetane 2 obtained by Synthesis Example 2 (GPC peak area ratio: 2.64%)

[0183] A1-3: Oxetane 3 obtained by Comparative Synthesis Example 1 (GPC peak area ratio: 5.66%)

[0184] A1-4: Oxetane 4 obtained by Comparative Synthesis Example 2 (GPC peak area ratio: 1.39%)

[0185] A1-5: 3-Ethyl-3-〔(2-ethylhexyloxy)methyl〕oxetane ("OXT-212" manufactured by Toagosei Co.)

[0186] [Chem. 11]

[0187]

[0188] An evaluation composition was prepared in the same manner as in Synthesis Example 1, using OXT-212 instead of oxetane 1, and the curability of OXT-212 was evaluated. The GPC peak area ratio was calculated in the same manner as in Synthesis Example 1, and the result was 8.23% Figure 2 ).

[0189] • Polyfunctional epoxy compound

[0190] A2-1: 3,3'-(oxybisdimethylene)bis(3-ethyloxetane) ("OXT-221" manufactured by Toagosei Co., Ltd.)

[0191] A2-2: 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate ("Celloxide 2021P" manufactured by Daicel Corp.)

[0192] <Photopolymerization initiator>

[0193] B-1: Photopolymerization initiator represented by Chemical Formula (I2-1) described in paragraph 0127 of Japanese Patent Laid-Open No. 2018-036533

[0194] <Antioxidant>

[0195] C-1: Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) ("Irganox 1010" manufactured by BASF Corp.)

[0196] <Surface active agent>

[0197] D-1: Fluorine-containing nonionic surface active agent ("F554" manufactured by DIC Corp.)

[0198] [Example 1]

[0199] A hardening composition was prepared by mixing 140 parts by mass of oxetane 1 as the compound (A1), 50 parts by mass of OXT-221 as the compound (A2), and 10 parts by mass of Celloxide 2021P as the compound (A2), 1 part by mass of the photopolymerization initiator represented by Chemical Formula (I2-1) described in paragraph 0127 of Japanese Patent Laid-Open No. 2018-036533 as the polymerization initiator, 0.1 part by mass of Irganox 1010 as the antioxidant, and 0.1 part by mass of F554 as the surface active agent in an atmospheric environment.

[0200] [Example 2 and Comparative Examples 1 to 3]

[0201] A hardening composition was prepared in the same manner as in Example 1 except that the kind and amount of the polymerizable compound were changed as described in Table 1.

[0202] 3. Evaluation

[0203] The hardening compositions of Example 1, Example 2, and Comparative Examples 1 to 3 were evaluated by the following methods. The evaluation results are shown in Table 1.

[0204] <Viscosity>

[0205] The viscosity of the curable composition was measured in accordance with JIS K2283 using an E-type viscometer (RE-85L manufactured by Tokimec, Inc., cone-rotor type: 1° 34' x R24) at 25°C at 20 rpm.

[0206] <Evaluation of wet spreading of inkjet coating>

[0207] For an evaluation substrate obtained by forming SiNx as a film thickness of 100 nm on a glass substrate, inkjet ejection of the curable composition was performed using 20 nozzles adjacent and continuous in an inkjet head SE-128AA (manufactured by FUJIFILM Dimatix, Inc.) installed on a piezoelectric type inkjet printer, nanoprinter 1500 (manufactured by Microjet Co., Ltd.), at a pitch of 50 μm x 50 μm to draw a line pattern of a width of 1000 μm x a length of 3 cm. Further, after 3 minutes, the line pattern was hardened using an LED lamp of 395 nm at an irradiance of 1000 mW / cm 2 , a cumulative light quantity of 1000 mJ / cm 2 . At this time, the droplet quantity per one drop was calculated from the ink mass when 100,000 drops were ejected per one nozzle and the density of the curable composition, and the waveform of the inkjet head was changed in a manner that one drop was 12 pL. For the obtained line pattern, the line pattern width was measured using an optical microscope, and evaluation was performed in accordance with the following criteria.

[0208] O: line pattern width was 1500 μm or more

[0209] Δ: line pattern width was 1000 μm or more and less than 1500 μm

[0210] X: line pattern width was less than 1000 μm

[0211] <Dielectric constant of hardened film>

[0212] In a glove box in which nitrogen substitution was performed at 25°C and a dew point of -60°C or lower (200 ppm), a substrate on which indium tin oxide (ITO) was vapor-deposited on an alkali-free glass at a thickness of 30 nm was coated with the curable composition in a manner that the thickness after hardening was 8 μm using a spin coater. Next, the line pattern was hardened using an LED UV lamp at an irradiance of 1000 mW / cm 2 , a cumulative light quantity of 1000 mJ / cm 2The curable composition was cured by irradiation of ultraviolet rays of 395 nm. As the LED UV lamp, UniJet E110Z HD (model U395A-455, manufactured by USHIO Inc.) was used. Thereafter, an aluminum film was vapor-deposited on the surface of the cured film at a thickness of 50 nm, and a test piece for dielectric constant measurement was produced. For the obtained test piece, a dielectric constant measuring device was used to measure the dielectric constant at 25°C and 100 kHz. As the dielectric constant measuring device, a 4284A-type inductance-capacitance-resistance meter (LCR meter) (manufactured by HEWLETT PACKARD) was used.

[0213] <Outgassing>

[0214] In a glove box in which nitrogen replacement had been performed, the curable composition was applied to a 6-inch silicon wafer so as to have a cured thickness of 8 μm using a spin coater. Next, the curable composition was cured by irradiation of ultraviolet rays of 395 nm using an LED UV lamp under conditions of illuminance of 1000 mW / cm 2 , and cumulative light amount of 1000 mJ / cm 2 . As the LED UV lamp, UniJet E110Z HD (model U395A-455, manufactured by USHIO Inc.) was used.

[0215] Thereafter, the 6-inch silicon wafer was cut out so as to have a size of 1 cm x 5 cm for each cured film, and a test piece for outgassing measurement was produced. The test piece was put in a vial for headspace, and the vial was sealed, and the vial was heated at 110°C for 30 minutes, and the gas generated was measured by a headspace method. A 400 ppm solution of toluene diluted with methanol was used as a reference substance, and the mass per unit area was calculated from the mass of toluene and the peak area of toluene. Then, the mass of the gas generated from the test piece was calculated from the total peak area of the gas generated from the test piece and the mass per unit area calculated from toluene. Finally, the ratio of the mass of the gas generated from the test piece to the mass of the film on the test piece was calculated, and thus the outgassing amount was calculated. As the outgassing measuring device, GCMS-QP2010plus (manufactured by SHIMADZU CORPORATION) was used.

[0216] : The generated gas was less than 250 ppm

[0217] : The generated gas was 250 ppm or more and less than 400 ppm

[0218] : The generated gas is 400 ppm or more and less than 800 ppm

[0219] : The generated gas is 800 ppm or more

[0220] In the evaluation, if the gas generated from the hardened film is less than 400 ppm ("O" or "D"), it can be said to have practicality.

[0221] [Table 1]

[0222]

[0223] As shown in Table 1, Example 1 and Example 2 using the monofunctional oxetane compound (Al) having a GPC peak area ratio of 5.0% or less as the polymerizable compound had a sufficiently small amount of gas generation from the hardened film, compared with Comparative Examples 1 to 3. In addition, the viscosity of the hardening composition of Example 1 and Example 2 was moderately low, and the inkjet coating wet spreading property was excellent. Furthermore, the dielectric constant of the hardened film obtained from the hardening composition of Example 1 and Example 2 was also low.

[0224] In addition, it is considered that, in Comparative Example 1 and Comparative Example 3, the monofunctional oxetane compound having a GPC peak area ratio of more than 5.0% was used instead of the monofunctional oxetane compound (Al) having a GPC peak area ratio of 5.0% or less, and thus the amount of unreacted monomer remaining in the hardened film after ultraviolet irradiation was large, and the amount of gas generation caused by the unreacted monomer was large. In addition, it is considered that the monofunctional oxetane compound (Al-4) used in Comparative Example 2 has a small steric hindrance, and the reactivity caused by ultraviolet irradiation is high, and on the other hand, the polymer formed with ultraviolet irradiation is easily decomposed, and the amount of gas generation caused by the decomposition product of the polymer is large.

Claims

1. A curable composition comprising: a monofunctional oxetane compound (Al); a polyfunctional epoxy compound (A2) which is at least one selected from the group consisting of a polyfunctional oxetane compound and a polyfunctional oxirane compound; and a polymerization initiator, in the curable composition, a ratio of a gel permeation chromatography peak area of the monofunctional oxetane compound (Al) is 5.0% or less as calculated by a curability evaluation shown below using gel permeation chromatography, A hardened film obtained by irradiating an ultraviolet ray of wavelength 395 nm to a coating film formed from the curable composition under the conditions of illuminance 1000 mW / cm 2 and cumulative light amount 1000 mJ / cm 2 did not exceed 400 ppm when the hardened film was heated. Curing evaluation: A cured film obtained by irradiating a coating film formed from a composition containing only the evaluation target compound as a polymerizable compound and also containing a polymerization initiator with ultraviolet light of wavelength 395 nm under conditions of illuminance 1000 mW / cm 2 and cumulative light amount 1000 mJ / cm 2 was immersed in tetrahydrofuran, and the tetrahydrofuran solution after the immersion was analyzed by gel permeation chromatography. The total peak area of the gel permeation chromatogram thus obtained was taken as the first peak area (S1), and the peak area of the peak in the gel permeation chromatogram of the tetrahydrofuran solution that originated from the residual component of the evaluation target compound was taken as the second peak area (S2). The ratio of the second peak area to the first peak area at this time (S2 / S1) was taken as the gel permeation chromatography peak area ratio.

2. The curable composition according to claim 1, wherein for an evaluation substrate obtained by film formation on a glass substrate using SiNx, an inkjet head including 20 nozzles arranged in a row in a direction orthogonal to a scanning direction is used, inkjet ejection is performed at a pitch of 50 μm x 50 μm, a line pattern of a width of 1000 μm is drawn, after standing for 3 minutes, the line pattern is exposed to ultraviolet rays of a wavelength of 395 nm under conditions of an illuminance of 1000 mW / cm2and an accumulated light amount of 1000 mJ / cm2to cure the line pattern, and the line pattern width at this time is 1500 μm or more. 2 and the accumulated light amount is 1000 mJ / cm2. 2 The line pattern width at this time is 1500 μm or more.

3. The curable composition according to claim 1, wherein a viscosity at 25°C is 1.0 mPa-s to 40.0 mPa-s.

4. The curable composition according to claim 1, wherein the monofunctional oxetane compound (Al) has two substituents at a 3-position of an oxetane ring.

5. The curable composition according to claim 1, wherein the monofunctional oxetane compound (Al) has a methyl group bonded to a 3-position of an oxetane ring.

6. The curable composition according to claim 1, wherein the monofunctional oxetane compound (Al) has no ether bond in a moiety other than an oxetane ring.

7. The curable composition according to claim 1, wherein the monofunctional oxetane compound (Al) has a linear or branched alkyl group of 6 to 20 carbon numbers bonded directly to an oxetane ring or via 1 -R 1 -O-. R 1 is an alkanediyl group having a carbon number of 1 to 3, 1 " represents a bond to the oxetane ring.

8. The curable composition according to claim 1, wherein a content of the monofunctional oxetane compound (Al) is 20 mass% to 60 mass% relative to a total amount of polymerizable compounds contained in the curable composition.

9. The curing composition according to claim 1, wherein the curing is achieved at an illuminance of 1000 mW / cm². 2 And the cumulative light intensity is 3000 mJ / cm 2 The dielectric constant of the hardened film obtained by irradiating the hardening composition with ultraviolet light at a wavelength of 395 nm under certain conditions is 2.8 or less at a frequency of 100 kHz.

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

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

12. A cured film formed using the curable composition according to any one of claims 1 to 11.

13. An organic electroluminescent element in which an organic light-emitting layer is sealed with the cured film according to claim 12.

14. A method for producing an organic electroluminescent element, comprising: a step of coating the curable composition according to any one of claims 1 to 11 on a light-emitting layer formation surface of a substrate on which an organic light-emitting layer is formed; and a step of forming a sealing structure by curing the curable composition by irradiation of a radiation.

15. The method for producing an organic electroluminescent element according to claim 14, wherein the curable composition is coated by inkjet coating. ​

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