Sealant for organic EL element, cured film, organic EL element, and method for producing organic EL element

Abstract

To provide a sealant for an organic EL element, which is capable of achieving both good wetting and spreading properties when applied to a substrate by an inkjet method and straightness of the edge of a film.SOLUTION: A sealant for an organic EL element includes [A] a polymerizable compound and [B] a polymerization initiator, and has a viscosity of 1 mPa s or more and 40 mPa s or less, as measured using an E-type viscometer at 25°C and 20 rpm. The sealant for the organic EL element contains, as the polymerizable compound [A], a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sealant for an organic EL device, a cured film, an organic EL device, and a method for producing an organic EL device. [Background technology]

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

[0003] The organic light-emitting layer of an organic EL element is easily deteriorated by contact with moisture and oxygen. For example, there is a concern that moisture that has infiltrated into the element over a long period of operation may cause partial non-emitting areas (dark spots) to form, or that light-emitting characteristics may be degraded by contact with moisture or oxygen. Thus, a sealing structure has been provided in the organic EL element to prevent the organic light-emitting layer from coming into contact with moisture or oxygen (see, for example, Patent Document 1). Patent Document 1 discloses that an organic sealing layer that covers the organic light-emitting layer is formed by applying and curing a curable composition containing a polymerizable compound and a polymerization initiator.

[0004] Furthermore, because a uniform coating film can be easily formed with a small amount of the curable composition and because it is excellent in terms of throughput, attempts have been made in recent years to form a sealing structure for an organic EL element by applying a curable composition onto a substrate by inkjet coating and curing the composition (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 225723 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to make it possible to apply inkjet coating when forming a sealing structure for an organic EL element, a curable composition for forming the sealing structure (hereinafter also referred to as a "sealant for organic EL elements") is required to have low viscosity and to have little coating unevenness in order to sufficiently cover the organic light-emitting layer. In particular, in order to accommodate the thinning of the sealing structure (for example, a structure with a thickness of 10 μm or less) associated with the thinning of organic EL elements, the sealant for organic EL elements is required to have good wetting and spreading properties. Therefore, it has been conventionally considered to improve the coatability of the sealant for organic EL elements by blending a surfactant into the sealant for organic EL elements.

[0007] However, the inventors have found that when the application of the sealant for organic EL elements is improved by using a surfactant, the edge line of the film formed by application on the substrate (i.e., the edge on both the left and right sides relative to the moving direction of the inkjet nozzle) tends to be curved or sawtooth, and linearity tends to be lost. In this case, there is a concern that an uncoated portion will be generated at the edge of the film, and the sealing of the organic light-emitting layer will be insufficient. From the viewpoint of improving the reliability of the organic EL element, it is required that the sealant for organic EL elements has good wetting and spreading properties when applied on the substrate and that the edge line of the film will be linear (hereinafter also referred to as "edge straightness").

[0008] The present invention has been made in consideration of the above problems, and has as its main object to provide a sealant for an organic EL element that can achieve both good wetting and spreading properties and straight edge properties of a film when applied to a substrate by an inkjet method. [Means for solving the problem]

[0009] According to the present invention, there are provided the following sealant for an organic EL device, a cured film, an organic EL device, and a method for producing an organic EL device.

[0010] [1] A sealant for an organic electroluminescence device, comprising: [A] a polymerizable compound; and [B] a polymerization initiator, and having a viscosity of 1 mPa s or more and 40 mPa s or less as measured at 25°C and 20 rpm using an E-type viscometer, wherein the polymerizable compound [A] is a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group. [2] A cured film formed from the sealant for organic electroluminescence devices according to [1] above. [3] An organic electroluminescence (EL) element having an emitting layer sealed with the sealing agent for organic electroluminescence (EL) elements described above in [2]. [4] A method for producing an organic EL element, comprising the steps of applying the sealant for an organic EL element according to [1] above to a surface of a substrate on which an organic luminescent layer is formed, and curing the sealant for an organic EL element by irradiating the surface with radiation to form a sealing structure. Effect of the Invention

[0011] The sealant for an organic EL device of the present invention can achieve both good wetting and spreading properties when applied onto a substrate by an inkjet method, as well as straightness of the edge of the film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Matters related to the embodiments will be described in detail below. In this specification, a numerical range described using "to" means that the numerical range includes the numerical ranges before and after "to" as the lower and upper limits.

[0013] <Sealant for organic electroluminescence devices> The sealant for organic EL devices of the present disclosure (hereinafter also referred to as "the sealant") is a curable composition used for thin film encapsulation (TFE: Thin Film Encapsulation) of organic electroluminescence devices (organic EL devices). The sealant has a viscosity of 1 mPa·s or more and 40 mPa·s or less, measured using an E-type viscometer at 25°C and 20 rpm. The sealant has such a low viscosity and is suitable for inkjet coating.

[0014] The present sealant contains a polymerizable compound [A] and a polymerization initiator [B]. The polymerizable compound [A] is a compound capable of generating a polymer in response to a stimulus. By heating the present sealant or irradiating the present sealant with radiation, a polymerization reaction of the polymerizable compound [A] proceeds, and a cured film is obtained. The present sealant may be a cationic polymerizable sealant in which curing proceeds by cationic polymerization of the polymerizable compound [A], or a radical polymerizable sealant in which curing proceeds by radical polymerization of the polymerizable compound [A].

[0015] Each component contained in the sealant and other components that may be blended as necessary are described below. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0016] Here, in this specification, the term "hydrocarbon group" includes chain-shaped hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain-shaped hydrocarbon group" means a straight-chain hydrocarbon group and a branched hydrocarbon group that do not include a cyclic structure in the main chain and are composed only of a chain structure. The chain-shaped hydrocarbon group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" means a hydrocarbon group that includes only an alicyclic hydrocarbon structure as a ring structure and does not include an aromatic ring structure. The alicyclic hydrocarbon group does not necessarily have to be composed only of an alicyclic hydrocarbon structure, and also includes those that have a chain structure as a part of it. The term "aromatic hydrocarbon group" means a hydrocarbon group that includes an aromatic ring structure as a ring structure. The aromatic hydrocarbon group does not necessarily have to be composed only of an aromatic ring structure, and may include a chain structure or an alicyclic hydrocarbon structure as a part of it. The ring structure of the alicyclic hydrocarbon group and the aromatic hydrocarbon group may have a substituent composed of a hydrocarbon structure. The term "cyclic hydrocarbon group" means a hydrocarbon group that includes an alicyclic hydrocarbon group and an aromatic hydrocarbon group. The term "structural unit" refers to a unit that mainly constitutes the main chain structure, and at least two units are contained in the main chain structure. "(Meth)acrylo" is a term that includes "acrylic" and "methacrylic". In this specification, it is also referred to as "epoxy group" to include "oxiranyl group" and "oxetanyl group".

[0017] <[A] Polymerizable compound> [Compound (A1)] The sealing agent contains, as the polymerizable compound [A], a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group. Examples of the polymerizable group contained in the compound (A1) include an oxetanyl group, an oxiranyl group, a vinyl ether group, an allyl ether group, a vinyl group, a (meth)acryloyl group, a vinylphenyl group, and a hydroxyl group. Among these, the polymerizable group contained in the compound (A1) is preferably an oxetanyl group, an oxiranyl group, a vinyl ether group, or a (meth)acryloyl group, and more preferably an oxetanyl group or a (meth)acryloyl group.

[0018] The number of polymerizable groups in the compound (A1) is not particularly limited. From the viewpoint of suppressing an increase in the viscosity of the sealant and achieving a good balance between wet spreadability and end straightness when the sealant is applied onto a substrate, the number of polymerizable groups in the compound (A1) is preferably 1 or 2, and more preferably 1.

[0019] The monovalent fluorinated hydrocarbon group (hereinafter, referred to as the “fluorine-containing group R f ") is a monovalent hydrocarbon group in which one or more hydrogen atoms have been replaced with a fluorine atom. f The number of carbon atoms of the fluorine-containing group R is preferably 2 or more, and more preferably 2 to 20. f From the viewpoint of achieving both the wetting and spreading properties of the sealant and the straightness of the film at the end portions, it is preferable that half or more of the hydrogen atoms in the monovalent hydrocarbon group are substituted with fluorine atoms, and it is more preferable that all but one hydrogen atom is substituted with a fluorine atom or that all hydrogen atoms are substituted with fluorine atoms.

[0020] Fluorine-containing group R f Among them, a fluorinated chain hydrocarbon group is preferable. The fluorinated chain hydrocarbon group may be saturated or unsaturated, and may be linear or branched. Specific examples of preferable fluorinated chain hydrocarbon groups include "-C m F 2m-1 ", -C n F2n H" or "-C n F 2n+1 ". Here, m is an integer of 2 or more, and n is an integer of 1 or more. From the viewpoint of improving the wettability and the straightness of the film edge in a well-balanced manner, m and n are preferably 3 or more, more preferably 5 or more, and even more preferably 7 or more. From the viewpoint of suppressing a decrease in the wettability and the straightness of the film, m and n are each preferably 20 or less, more preferably 15 or less, and even more preferably 12 or less.

[0021] Fluorine-containing group R f When R is a fluorinated chain hydrocarbon group, it is preferable that the fluorinated chain hydrocarbon group has a carbon-carbon unsaturated bond, since this is highly effective in improving the balance between the wetting and spreading properties and the straightness of the film edge when the sealant is applied to a substrate. The number of unsaturated carbon-carbon bonds that the fluorinated chain hydrocarbon group has is not particularly limited. The number of unsaturated carbon-carbon bonds that the fluorinated chain hydrocarbon group has is preferably one. Note that the fluorine-containing group R f The carbon-carbon unsaturated bonds in the copolymer are non-polymerizable and are not thought to be involved in polymerization.

[0022] The fluorine-containing group R of the compound (A1) f The number of fluorine-containing groups R contained in the compound (A1) is not particularly limited. f The number of is preferably 1 or 2, and particularly preferably 1.

[0023] The fluorine-containing group R of the compound (A1) f Specific examples of the group include groups represented by the following formulae (f-1) to (f-14). [ka] [ka] (In formulas (f-1) to (f-14), "*" represents a bond.)

[0024] A preferred specific example of the compound (A1) is a compound represented by the following formula (1). [ka] (In formula (1), X 1 Y is a monovalent group having an oxetanyl group, an oxiranyl group, a vinyl ether group, or a (meth)acryloyl group. 1 R is a divalent group containing -O- between the carbon-carbon bonds of an alkanediyl group having 1 to 10 carbon atoms or an alkanediyl group having 2 to 10 carbon atoms. f "-C m F 2m-1 ", -C n F 2n H" or "-C n F 2n+1 " where m is an integer of 2 or more, and n is an integer of 1 or more.)

[0025] In the above formula (1), R f Specific and preferred examples of the monovalent fluorinated chain hydrocarbon group represented by the formula Y are as described above. 1 Y may be linear or branched. 1 From the viewpoint of the availability of raw materials, the number of carbon atoms is preferably 1 to 8, and more preferably 1 to 5.

[0026] [Compound (A2)] The present sealing agent is a polymerizable compound [A] that is copolymerizable with the compound (A1) and contains a fluorine-containing group R f It is preferable that the sealant further contains a compound not having the formula (hereinafter, also referred to as "compound (A2)"). By blending compound (A2) in the sealant, it is possible to easily adjust the viscosity of the sealant, increase the curability, and reinforce the crosslinked structure.

[0027] The compound (A2) may include a fluorine-containing group R f and a monofunctional polymerizable compound not having a fluorine-containing group R fand polyfunctional polymerizable compounds not having a monofunctional group (hereinafter also referred to as "polyfunctional compounds (A2n)"). The present sealant preferably contains, as the compound (A2), a monofunctional compound (A2m) and a polyfunctional compound (A2n). The polymerizable groups possessed by the monofunctional compound (A2m) and the polyfunctional compound (A2n) can be appropriately selected depending on the polymerizable group possessed by the compound (A1) to be blended in the present sealant.

[0028] The polyfunctional compound (A2n) contained in the present sealant may contain a siloxane compound having two or more polymerizable groups (hereinafter, also referred to as "polyfunctional siloxane compound"). By containing a polyfunctional siloxane compound in the present sealant, it is possible to improve the curability while lowering the dielectric constant. Examples of the polyfunctional siloxane compound include siloxane compounds having a chain structure or a cyclic structure. The polymerizable group of the polyfunctional siloxane compound can be appropriately selected depending on the polymerizable group of the compound (A1) to be blended in the present sealant.

[0029] Specific examples of the polyfunctional siloxane compound include compounds represented by the following formula (3-1) or formula (3-2). [ka] (In formula (3-1) and formula (3-2), R 5 and R 6 are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a group having a polymerizable group. a is an integer of 0 to 100. b is an integer of 1 to 18. However, when multiple R 5 At least two of R in formula (3-2) are groups having a polymerizable group. 6 At least two of R are groups having a polymerizable group. 5 are the same or different, and multiple R 6 are the same or different.)

[0030] In the polymerizable compound [A], the content of the compound (A1) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, based on 100 parts by mass of the total amount of the polymerizable compound [A], from the viewpoint of obtaining a sufficient effect of improving the wet spreadability and the straightness of the edge of the film when the sealant is applied to a substrate. Also, from the viewpoint of suppressing the decrease in the wet spreadability, the content of the compound (A1) is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable compound [A].

[0031] The ratio of the monofunctional compound (A2m) in the compound (A2) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the total amount of the compound (A2) (i.e., the total amount of the monofunctional compound (A2m) and the polyfunctional compound (A2n)). The content of the monofunctional compound (A2m) is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, based on 100 parts by mass of the total amount of the compound (A2). When the content of the monofunctional compound (A2m) is within the above range, a sealant for organic EL elements having low viscosity and excellent curability can be obtained.

[0032] When the sealing agent contains a polyfunctional siloxane compound, the content of the polyfunctional siloxane compound is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the total amount of the compound (A2). The content of the polyfunctional siloxane compound is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, based on 100 parts by mass of the total amount of the compound (A2).

[0033] Next, when the present sealant is a cationic polymerizable sealant or a radical polymerizable sealant, the polymerizable compound [A] and the polymerization initiator [B] contained in each sealant will be described in detail.

[0034] <Cationic Polymerizable Sealing Agent> [[A] Polymerizable compound] ·Compound (A1) When the present sealant is a cationic polymerizable sealant, examples of the polymerizable group contained in the compound (A1) (hereinafter, "compound (A1-c)") contained in the present sealant include an oxetanyl group, an oxiranyl group, a vinyl ether group, an allyl ether group, a vinyl group, and a hydroxyl group. Among these, the polymerizable group contained in the compound (A1-1) is preferably an oxetanyl group or an oxiranyl group, and more preferably an oxetanyl group. The fluorine-containing group R contained in the compound (A1-c) f The above explanations apply to specific and preferred examples.

[0035] A preferred specific example of the compound (A1-c) is a compound represented by the following formula (1-1). [ka] (In formula (1-1), R 1 R is a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, or an allyl group. f "-C m F 2m-1 ", -C n F 2n H" or "-C n F 2n+1 " is a monovalent fluorinated chain hydrocarbon group represented by the formula: m is an integer of 2 or more, n is an integer of 1 or more, and k is an integer of 1 to 10.

[0036] In the above formula (1-1), R f Specific and preferred examples of the monovalent fluorinated chain hydrocarbon group represented by the formula: are as described above. R 1 Examples of the alkyl group represented by the formula (I) include linear or branched alkyl groups having 1 to 10 carbon atoms. 1 Examples of the fluoroalkyl group represented by the formula (I) include a linear or branched alkyl group having 1 to 10 carbon atoms in which one or more hydrogen atoms have been substituted with a fluorine atom. 1 The alkyl group and the fluoroalkyl group represented by the following formula (I) preferably have 1 to 5 carbon atoms, and more preferably have 1 to 3 carbon atoms. 1From the viewpoint of reactivity, the alkyl group is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. k is preferably an integer of 1 to 5, and more preferably an integer of 1 to 3.

[0037] Specific examples of the compound (A1-c) include the compounds represented by the following formulas (a1-1-1) to (a1-1-18). [ka] [ka]

[0038] In the cationic polymerizable sealant, the content of the compound (A1-c) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, based on 100 parts by mass of the total amount of the polymerizable compound [A]. The content of the compound (A1-c) is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable compound [A]. When the content of the compound (A1-c) is in the above range, the sealant can exhibit a good balance between the wet spreadability and the straightness of the edge of the film when applied to a substrate, and is also suitable in that the wet spreadability and the straightness of the edge of the film can be made more excellent.

[0039] ·Compound (A2) When the present sealant is a cationic polymerizable sealant, the compound (A2) (hereinafter, "compound (A2-c)") contained in the present sealant may be a compound having an oxetanyl group, an oxiranyl group, a vinyl group, a vinyl ether group, an allyl ether group, or a hydroxyl group as a polymerizable group. Among these, from the viewpoint of cationic polymerizability, the compound (A2-c) is preferably a compound having an oxetanyl group, an oxiranyl group, or a vinyl ether group, and more preferably a compound having an oxetanyl group or an oxiranyl group. In addition, the compound (A2-c) may be either a monofunctional polymerizable compound or a polyfunctional polymerizable compound. As the compound (A2-c), a monofunctional epoxy compound, a polyfunctional epoxy compound, or both of them can be preferably used.

[0040] As the monofunctional polymerizable compound, a monofunctional oxetane compound can be preferably used. Specific examples of the monofunctional oxetane compound include 3-ethyl-3-((2-ethylhexyloxy)methyl)oxetane, 3-methyl-3-methoxyoxetane, phenyloxetane, phenoxymethyloxetane, 3-ethyl-3-(phenoxymethyl)oxetane, 3-ethyl-3-((3-(triethoxysilyl)propoxy)methyl)oxetane, 3-allyloxyoxetane, 3-ethyl-3-allyloxyoxetane, 2-methyl-2-aryloxyoxetane, 2-phenyl-2-phenyl ... Examples of the acryloyloxymethyloxetane include 3-ethyl-4-propyloxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-chloromethyloxetane, 3-amino-3-dimethyloxetane, 3-ethyl-3-(meth)acryloyloxymethyloxetane, 3-ethyl-3-(4-(meth)acryloyloxybutyloxymethyl)oxetane, and 3-ethyl-3-(3-(meth)acryloyloxy-2,2-dimethylpropyloxymethyl)oxetane.

[0041] Specific examples of polyfunctional oxetane compounds include 3-ethyl-3-(((3-ethyloxetan-3-yl)methoxy)methyl)oxetane, xylylene bisoxetane, 1,4-bis((3-ethyl-3-oxetanylmethoxy)methyl)benzene, bis((3-methyl-3-oxetanylmethoxy)methyl)ether, bis((3-ethyl-3-oxetanylmethoxy)methyl)ether, 1,4-bis((3-methyl-3-oxetanylmethoxy)methyl)benzene, as well as oligomers or copolymers of these compounds, phenol novolac-type oxetane, oxetanyl silsesquioxane, and ethers of the above polyfunctional oxetane compounds with hydroxyl group-containing resins (e.g., calixarenes, calixresorcinarenes, cardo-type bisphenols, poly(p-hydroxystyrene), etc.). From the viewpoint of inkjet coating properties, the polyfunctional oxetane compound is preferably a compound having a molecular weight of 500 or less, more preferably a compound having a molecular weight of 400 or less. From the same viewpoint, a bifunctional oxetane compound can be preferably used.

[0042] When the present sealant is a cationic polymerizable sealant, the present sealant preferably contains a siloxane compound having two or more cationic polymerizable groups as a polyfunctional polymerizable compound (hereinafter, also referred to as "polyfunctional siloxane compound (A3-c)"). By blending the polyfunctional siloxane compound (A3-c) in the present sealant, it is possible to improve the curability while lowering the dielectric constant.

[0043] The polyfunctional siloxane compound (A3-c) may be a siloxane compound having a chain structure or a cyclic structure. The polyfunctional siloxane compound (A3-c) preferably has two or more oxetanyl groups or oxiranyl groups as cationic polymerizable groups. The number of cationic polymerizable groups in the polyfunctional siloxane compound (A3-c) is preferably 2 to 8, more preferably 2 to 4. From the viewpoint of inkjet coating properties, among these, a bifunctional epoxy group-containing siloxane compound can be particularly preferably used as the polyfunctional siloxane compound (A3-c).

[0044] Specific examples of the polyfunctional siloxane compound (A3-c) include trade names such as "X-22-163", "X-22-169", "KR-470", "X-40-2678", "X-40-2669", and "X-40-2728" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0045] The cationic polymerizable sealing agent preferably contains a monofunctional polymerizable compound and a polyfunctional polymerizable compound as the compound (A2-c). The ratio of the monofunctional polymerizable compound to the total amount of the compound (A2-c) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the total amount of the compound (A2-c). The ratio of the monofunctional polymerizable compound to the total amount of the compound (A2-c) is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, relative to 100 parts by mass of the total amount of the compound (A2-c). By setting the ratio of the monofunctional polymerizable compound to the polyfunctional polymerizable compound in the above range, a sealing agent for organic EL elements having an excellent balance between low viscosity and curability can be obtained.

[0046] From the viewpoint of ensuring the curability of the sealant, the content of compound (A2-c) is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, based on 100 parts by mass of the total amount of the polymerizable compounds [A] contained in the sealant (i.e., compounds (A1-c) and (A2-c)). Also, from the viewpoint of fully obtaining the effect of improving the coatability by blending compound (A1-c), the content of compound (A2-c) is preferably 99.9 parts by mass or less, more preferably 99.5 parts by mass or less, and even more preferably 99 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable compounds [A] contained in the sealant.

[0047] In the present sealant, the content of the polyfunctional siloxane compound (A3-c) is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the total amount of the compounds (A2-c). The content of the polyfunctional siloxane compound (A3-c) is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, based on 100 parts by mass of the total amount of the compounds (A2-c).

[0048] [B] Polymerization initiator When the present sealant is a cationic polymerizable sealant, the present sealant contains a cationic polymerization initiator as the polymerization initiator [B]. Examples of the cationic polymerization initiator include a thermal cationic polymerization initiator that generates a protonic acid or Lewis acid in response to heat, and a photo-cationic polymerization initiator that generates a protonic acid or Lewis acid in response to radiation. Examples of the thermal cationic polymerization initiator include an ionic thermal acid generating type polymerization initiator. Examples of the photo-cationic polymerization initiator include an ionic photo-acid generating type polymerization initiator and a non-ionic photo-acid generating type polymerization initiator. Considering that the present sealant is used for an organic EL device, a photo-cationic polymerization initiator can be preferably used.

[0049] Specific examples of the thermal cationic polymerization initiator include sulfonium salts, phosphonium salts, diazonium salts, iodonium salts, and quaternary ammonium salts. The thermal cationic polymerization initiator is preferably an arylsulfonium salt, an arylphosphonium salt, an aryldiazonium salt, an aryliodonium salt, or a quaternary ammonium salt, and the counter anion in these onium salts is preferably BF4 - , PF6 - , SbF6 - or BX4 - (wherein X represents a substituted phenyl group in which two or more hydrogen atoms of the phenyl group have been substituted with fluorine or trifluoromethyl groups) is more preferable.

[0050] Specific examples of photocationic polymerization initiators include ionic photoacid generating photocationic polymerization initiators, such as onium salt compounds, halogen-containing compounds, sulfone compounds, sulfonic acid compounds, sulfonimide compounds, and diazomethane compounds. Examples of onium salt compounds include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, (2,4-cyclopentadiene-1-yl)[(1-methylethyl)benzene]-Fe salts, and the like. Specific examples of onium salt compounds include compounds in which the cation portion is an aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, or (2,4-cyclopentadiene-1-yl)[(1-methylethyl)benzene]-Fe cation and the anion portion is BF4 - , PF6 - , SbF6, BX4 - (wherein X represents a substituted phenyl group in which two or more hydrogen atoms of the phenyl group are replaced by fluorine or trifluoromethyl groups), or PY6 - (wherein Y is a fluorinated alkyl group).

[0051] Examples of the non-ionic photoacid generating cationic photopolymerization initiator include nitrobenzyl esters, sulfonic acid derivatives, phosphoric acid esters, phenolsulfonic acid esters, diazonaphthoquinones, and N-hydroxyimidesulfonates.

[0052] The content of the cationic polymerization initiator in the sealant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the total amount of the polymerizable compound [A] contained in the sealant. The content of the cationic polymerization initiator is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable compound [A] contained in the sealant. By setting the content of the cationic polymerization initiator within the above range, good curability and the like can be exhibited.

[0053] <Radical polymerizable sealing agent> [[A] Polymerizable compound] ·Compound (A1) When the present sealant is a radically polymerizable sealant, examples of the polymerizable group possessed by the compound (A1) (hereinafter, "compound (A1-r)") contained in the present sealant include a (meth)acryloyl group and a vinylphenyl group. Among these, the polymerizable group possessed by the compound (A1-r) is preferably a (meth)acryloyl group. The fluorine-containing group R possessed by the compound (A1-r) f The above explanations apply to specific and preferred examples.

[0054] A preferred specific example of the compound (A1-r) is a compound represented by the following formula (1-2). [ka] (In formula (1-2), R 2 is a hydrogen atom or a methyl group. 3 and R 4 Y each independently represents a hydrogen atom, a fluorine atom, an alkyl group or a fluoroalkyl group. 1 R is a divalent group containing -O- between the carbon-carbon bonds of an alkanediyl group having 1 to 10 carbon atoms or an alkanediyl group having 2 to 10 carbon atoms. f "-C m F 2m-1 ", -C n F 2n H" or "-C n F 2n+1 " where m is an integer of 2 or more, and n is an integer of 1 or more.)

[0055] In the above formula (1-2), R f Specific and preferred examples of the monovalent fluorinated chain hydrocarbon group represented by the formula Y are as described above. 1 Preferably, it has 1 to 8 carbon atoms, and more preferably 1 to 5 carbon atoms.

[0056] R 3 and R 4 Examples of the alkyl group represented by the formula (I) include linear or branched alkyl groups having 1 to 10 carbon atoms.3 and R 4 Examples of the fluoroalkyl group represented by the formula (I) include a linear or branched alkyl group having 1 to 10 carbon atoms in which one or more hydrogen atoms have been substituted with a fluorine atom. 3 and R 4 The alkyl group and the fluoroalkyl group represented by the following formula (I) preferably have 1 to 5 carbon atoms, and more preferably have 1 to 3 carbon atoms. 3 and R 4 Of these, a hydrogen atom or a methyl group is preferable, and a hydrogen atom is more preferable.

[0057] Specific examples of the compound (A1-r) include the compounds represented by the following formulas (a1-2-1) to (a1-2-8). [ka] (In formulas (a1-2-1) to (a1-2-8), R 2 is a hydrogen atom or a methyl group. r is an integer of 0 to 4.

[0058] In the radical polymerizable sealing agent, the content of the compound (A1-r) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, based on 100 parts by mass of the total amount of the polymerizable compound [A]. The content of the compound (A1-r) is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable compound [A]. When the content of the compound (A1-r) is in the above range, it is preferable in that the effect of improving the wet spreadability and the straightness of the edge of the film in a well-balanced manner when the sealing agent is applied to a substrate can be enhanced.

[0059] ·Compound (A2) When the present sealant is a radically polymerizable sealant, a compound having an ethylenically unsaturated group can be preferably used as the compound (A2) (hereinafter, "compound (A2-r)") contained in the present sealant. Specific examples include vinyl group-containing compounds, (meth)acryloyl group-containing compounds, and aromatic vinyl compounds. Among these, a (meth)acryloyl group-containing compound is preferably used in terms of copolymerizability with compound (A1) and the relative ease with which the viscosity of the present sealant can be adjusted.

[0060] The compound (A2-r) may be either a monofunctional polymerizable compound or a polyfunctional polymerizable compound. Specific examples of the compound (A2-r) that is a monofunctional polymerizable compound include (meth)acrylic acid alkyl esters, (meth)acrylic acid esters having an alicyclic structure, (meth)acrylic acid esters having an aromatic ring structure, and aromatic vinyl compounds.

[0061] Further specific examples of the compound (A2-r) when it is a monofunctional polymerizable compound include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-lauryl (meth)acrylate, and n-stearyl (meth)acrylate. Examples of (meth)acrylic acid esters having an alicyclic structure include cyclohexyl (meth)acrylate, 2-methylcyclohexyl (meth)acrylate, tricyclo[5.2.1.0]methacrylate, and the like. 2,6 ]decan-8-yl, (meth)acrylic acid tricyclo[5.2.1.0 2,5]decan-8-yloxyethyl, isobornyl (meth)acrylate, etc. Examples of (meth)acrylic acid esters having an aromatic ring structure include phenyl (meth)acrylate, benzyl (meth)acrylate, naphthyl methyl (meth)acrylate, naphthyl ethyl (meth)acrylate, phenoxyethyl (meth)acrylate, m-phenoxyphenyl methyl (meth)acrylate, o-phenyl phenoxyethyl (meth)acrylate, etc. Examples of aromatic vinyl compounds include styrene, methylstyrene, α-methylstyrene, t-butoxystyrene, vinylnaphthalene, etc.

[0062] When the compound (A2-r) is a polyfunctional polymerizable compound, a polyfunctional (meth)acrylic acid ester can be preferably used as the compound (A2-r). Examples of the polyfunctional (meth)acrylic acid ester include bifunctional (meth)acrylic acid esters and trifunctional or higher (meth)acrylic acid esters. Specific examples of these include bifunctional (meth)acrylic acid esters such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and tricyclodecane dimethanol (meth)acrylate.

[0063] Examples of the trifunctional or higher (meth)acrylic acid ester include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, tri(2-(meth)acryloyloxyethyl)phosphate, succinic acid-modified pentaerythritol tri(meth)acrylate, Examples include succinic acid-modified dipentaerythritol penta(meth)acrylate, isocyanuric acid EO-modified di- and triacrylate, trimethylolpropane EO-modified tri(meth)acrylate, and carboxyl group-containing polybasic acid-modified (meth)acrylic oligomer, as well as polyfunctional urethane acrylate compounds obtained by reacting a compound having a linear alkylene group and an alicyclic structure and having two or more isocyanate groups with a compound having one or more hydroxyl groups in the molecule and having three, four or five (meth)acryloyloxy groups.

[0064] When the present sealant is a radically polymerizable sealant, a siloxane compound having two or more cationic polymerizable groups (hereinafter, also referred to as "polyfunctional siloxane compound (A3-r)") may be used as the polyfunctional polymerizable compound. Examples of the polyfunctional siloxane compound (A3-r) include siloxane compounds having a chain structure or a cyclic structure. The polyfunctional siloxane compound (A3-r) preferably has two or more (meth)acryloyl groups as the radically polymerizable group. The number of radically polymerizable groups in the polyfunctional siloxane compound (A3-r) is preferably 2 to 8, more preferably 2 to 4.

[0065] The radical polymerizable sealing agent preferably contains a monofunctional polymerizable compound and a polyfunctional polymerizable compound as the compound (A2-r). The ratio of the monofunctional polymerizable compound to the total amount of the compound (A2-r) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the total amount of the compound (A2-r). The ratio of the monofunctional polymerizable compound to the total amount of the compound (A2-r) is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, relative to 100 parts by mass of the total amount of the compound (A2-r). By setting the ratio of the monofunctional polymerizable compound to the polyfunctional polymerizable compound in the above range, a sealing agent for organic EL elements having low viscosity and excellent curability can be obtained.

[0066] From the viewpoint of ensuring the curability of the sealant, the content of the compound (A2-r) is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, and even more preferably 80 parts by mass or more, based on 100 parts by mass of the total amount of the polymerizable compound [A] contained in the sealant (i.e., compound (A1-r) and compound (A2-r)). Also, from the viewpoint of obtaining a sufficient effect of improving the coatability by blending the compound (A1-r), the content of the compound (A2-r) is preferably 99.9 parts by mass or less, more preferably 99.5 parts by mass or less, and even more preferably 99 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable compound [A] contained in the sealant.

[0067] [B] Polymerization initiator When the present sealant is a radical polymerizable sealant, the present sealant contains a radical polymerization initiator as the polymerization initiator [B]. Examples of the radical polymerization initiator include a thermal radical polymerization initiator that generates radicals in response to heat, and a photoradical polymerization initiator that generates radicals in response to radiation. Examples of the thermal radical polymerization initiator include an azo compound, an organic peroxide, and the like. Examples of the photoradical polymerization initiator include an O-acyloxime compound, an acetophenone compound, a biimidazole compound, an acylphosphine oxide compound, and the like. Considering that the present sealant is used for an organic EL device, a photoradical polymerization initiator can be preferably used.

[0068] Specific examples of the thermal radical polymerization initiator include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(isobutyric acid) dimethyl, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), etc. Examples of the organic peroxide include benzoyl peroxide, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, peroxydicarbonate, etc.

[0069] Specific examples of photoradical polymerization initiators include O-acyloxime compounds such as 1,2-octanedione 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), 1-(9-ethyl-6-benzoyl-9.H.-carbazol-3-yl)-octan-1-one oxime-O-acetate, 1-[9-ethyl-6-(2-methylbenzoyl)-9.H.-carbazol-3-yl]-ethane-1-one oxime-O-benzoate, and 1-[9-n-butyl-6-(2-ethylbenzoyl)-9.H.-carbazol-3-yl]-ethane-1-one oxime-O-benzoate. , ethanone-1-[9-ethyl-6-(2-methyl-4-tetrahydrofuranylbenzoyl)-9.H.-carbazol-3-yl]-1-(O-acetyloxime), ethanone-1-[9-ethyl-6-(2-methyl-4-tetrahydropyranylbenzoyl)-9.H.-carbazol-3-yl]-1-(O-acetyloxime), ethanone-1-[9-ethyl-6-(2-methyl-5-tetrahydrofuranylbenzoyl)-9.H.-carbazol-3-yl]-1-(O-acetyloxime), ethanone-1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolanyl)methoxybenzoyl}-9.H.-carbazol-3-yl]-1-(O-acetyloxime), and the like. Of the O-acyloxime compounds, polymerization initiators having a carbazole skeleton in the molecule (for example, ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) and the like) can be preferably used.

[0070] Examples of the acetophenone compound include α-aminoketone compounds and α-hydroxyketone compounds. Specific examples of these include α-aminoketone compounds such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one. Examples of the α-hydroxyketone compound include 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-(4-i-propylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, and 1-hydroxycyclohexylphenylketone.

[0071] Examples of the biimidazole compound include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, and 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole.

[0072] Examples of the acylphosphine oxide compound include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0073] The content of the radical polymerization initiator in the present sealant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the total amount of the polymerizable compound [A] contained in the present sealant. The content of the radical polymerization initiator is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable compound [A] contained in the present sealant. By setting the content of the radical polymerization initiator within the above range, good curability and the like can be exhibited.

[0074] <Other ingredients> The present sealant (including the cationic polymerizable sealant and the radical polymerizable sealant) may further contain, in addition to the above-mentioned polymerizable compound [A] and polymerization initiator [B], a component different from the polymerizable compound [A] and the polymerization initiator [B] (hereinafter, also referred to as "other components"). Examples of the other components include a polymerization inhibitor, a surfactant, an antioxidant, a sensitizer, a softener, a plasticizer, an adhesion aid, an organic solvent, and the like. The blending ratio of these components is appropriately selected according to each component within a range that does not impair the effects of the present disclosure.

[0075] If necessary, an organic solvent may be added to the sealant for the purpose of dissolving each component to be added to the sealant. However, from the viewpoint of enabling the formation of a cured film (more specifically, an organic sealing layer that protects the organic light-emitting layer of an organic EL element) without heat treatment, it is preferable to minimize the use of organic solvents. Specifically, the content of organic solvents in the sealant 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 free of organic solvents. Here, in this specification, "substantially free of" a certain component means that the amount of the specific component contained in the sealant is 1% by mass or less, preferably 0.5% by mass or less.

[0076] When an organic solvent is blended in the sealant, the organic solvent used is preferably an organic solvent that can dissolve or disperse each component blended in the sealant and does not react with each component.Specific examples of the organic solvent include alcohols, ketones, esters, ethers, aromatic hydrocarbons, and amides.

[0077] Specific examples of these include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol. Ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Esters include ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and methyl-3-methoxypropionate. Ethers include polyoxyethylene lauryl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and diethylene glycol methyl ethyl ether. Aromatic hydrocarbons include benzene, toluene, and xylene. Amides include dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0078] The present sealant contains the compound (A1), which can suppress the occurrence of coating unevenness when inkjet coating is adopted. Therefore, even if a surfactant used for the purpose of improving the coating property (wetting spreadability and reduction of coating unevenness) of the curable composition is not blended, or even if the blending amount of the surfactant is reduced as much as possible, the coating property of the present sealant can be ensured. This allows the ratio of the polymerizable compound [A] to the total amount of the present sealant to be increased as much as possible, and a sealant with high curability can be obtained. Examples of surfactants used in the preparation of the curable composition for forming the sealing structure of an organic EL element include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants.

[0079] From the viewpoint of achieving a good balance between excellent wetting and spreading properties and end straightness, and from the viewpoint of increasing the content ratio of the polymerizable compound [A] relative to the total amount of the present sealant as much as possible to enhance curability, the content ratio of the surfactant in the present sealant is preferably 0 mass% or more and 1 mass% or less, more preferably 0 mass% or more and 0.5 mass% or less, and even more preferably 0 mass% or more and 0.1 mass% or less.

[0080] <Preparation of sealant for organic EL devices> The sealant can be prepared by mixing the polymerizable compound [A] and the polymerization initiator [B], as well as other components that are blended as necessary. The content of the polymerizable compound [A] in the sealant is preferably 80 parts by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on 100 parts by mass of the total amount of the sealant, from the viewpoint of obtaining a curable composition with good sensitivity and forming a cured film with high sealing effect.

[0081] <Viscosity of encapsulant for organic EL devices> The viscosity of the sealant measured at 25°C and 20 rpm using an E-type viscometer is in the range of 1 to 40 mPa·s. If the viscosity of the sealant exceeds 40 mPa·s, the wetting and spreading properties of the sealant when applied to a substrate by inkjet coating are reduced, and coating unevenness is likely to occur. In particular, there is concern that coating unevenness is likely to occur when trying to make the organic sealing layer thinner as the organic EL element becomes thinner. On the other hand, if the viscosity of the sealant is less than 1 mPa·s, the sealant may be scattered or dripped during inkjet coating, resulting in a state in which the sealant is attached in dots (satellites) other than the intended location. In this case, an organic sealing layer with a sufficiently high sealing effect may not be formed. In this regard, the sealant is particularly suitable as a curable composition for inkjet coating because it can suppress the scattering and dripping of the sealant during inkjet coating (i.e., it has excellent inkjet discharge stability) in addition to the wetting and spreading properties.

[0082] From the viewpoint of obtaining a curable composition having good wetting and spreading properties and excellent inkjet coating properties, the viscosity of the sealant is more preferably 35 mPa·s or less, even more preferably 30 mPa·s or less, and even more preferably 25 mPa·s or less. Moreover, from the viewpoint of improving the inkjet discharge stability and suppressing the occurrence of satellites, the viscosity of the sealant is more preferably 2 mPa·s or more, and even more preferably 5 mPa·s or more. In this specification, the viscosity of the sealant for organic EL devices is a value measured in accordance with JIS K2283.

[0083] <Surface tension of sealant for organic EL devices> The surface tension of the sealant at 25°C is preferably 15 mN / m or more and 40 mN / m or less. By having the surface tension in the above range, a curable composition having excellent inkjet applicability can be obtained. From the viewpoint of improving the applicability when applied to inkjet coating, the surface tension of the sealant at 25°C is more preferably 20 mN / m or more, and even more preferably 23 mN / m or more. Moreover, the surface tension of the sealant at 25°C is more preferably 35 mN / m or less, and even more preferably 33 mN / m or less. In this specification, the surface tension of the sealant for organic EL elements is a value measured at 25°C by the Wilhelmy method using a surface tensiometer.

[0084] <Cured film and organic EL element> The cured film of the present disclosure (hereinafter also referred to as "the present cured film") is formed by the present encapsulant prepared as described above. The present cured film is particularly useful as a thin film encapsulation (TFE) structure for an organic EL device. The present cured film and an organic EL device having an encapsulation structure in which an organic light-emitting layer is encapsulated by the present cured film can be produced by curing the present encapsulant with heat or radiation. When obtaining the organic EL device, it is preferable to form an encapsulation structure for the organic light-emitting layer by irradiating the present encapsulant with radiation, and specifically, the organic EL device can be produced by a method including the following steps 1 and 2. (Step 1) A step of applying the present sealant to the light-emitting layer-forming surface of a substrate on which an organic light-emitting layer has been formed. (Step 2) A step of curing the sealant by irradiating it with radiation. Each step will be described in detail below.

[0085] [Process 1: Coating process] In this process, the present sealant is applied to the light-emitting layer forming surface of the substrate on which the organic light-emitting layer is formed, thereby forming a coating film made of the present sealant on the light-emitting layer forming surface. The substrate to which the present sealant is applied has a laminate including various layers such as an anode layer, a hole injection layer, a hole transport layer, an electron injection layer, and a cathode layer in addition to the organic light-emitting layer, and this laminate constitutes an organic EL element. The light-emitting layer forming surface to which the present sealant is applied may be covered with an inorganic film (inorganic sealing layer). Examples of inorganic materials constituting the inorganic film include silicon nitride (SiNx) and silicon oxide (SiOx). In this case, a thin film sealing layer including an organic sealing layer and an inorganic sealing layer is formed as a sealing structure on the organic light-emitting layer.

[0086] Examples of methods for applying the sealant include spraying, roll coating, spin coating, slit die coating, bar coating, and inkjet coating. Among these, the inkjet coating method is preferably used from the viewpoints of throughput and thinning. In particular, the sealant is suitable for inkjet coating because it has low viscosity and excellent curability.

[0087] [Process 2: Curing process] In this step, the coating film formed in step 1 above is irradiated with radiation to cure the coating film into a cured film. Examples of radiation include ultraviolet light, far ultraviolet light, visible light, X-rays, and charged particle beams such as electron beams. Among these, ultraviolet light is preferred, and for example, ultraviolet light having a wavelength of 350 to 400 nm can be preferably used as the irradiation light. The radiation exposure dose is 0.05 to 10 J / m 2is preferable. This makes it possible to obtain an organic EL element in which the organic light-emitting layer is covered with an organic sealing layer made of the present sealant. In particular, the present sealant has good wettability and spreadability, and the use of the present sealant makes it possible to make the organic sealing layer thinner (and thus the sealing structure of the organic EL element thinner). The thickness of the cured film (organic sealing layer) formed by the present sealant is usually 0.5 to 15 μm, preferably 0.5 to 10 μm, and more preferably 0.5 to 8 μm. The organic sealing layer formed by the present sealant may be further covered with an inorganic film. Examples of inorganic materials constituting the inorganic film include silicon nitride (SiNx) and silicon oxide (SiOx).

[0088] In the organic EL element of the present disclosure manufactured by the method including the above-mentioned steps 1 and 2, the organic light-emitting layer is sealed with an organic sealing layer made of the present composition. Therefore, the organic EL element of the present disclosure can sufficiently suppress the intrusion of moisture into the organic light-emitting layer, and can realize a thin organic sealing layer while suppressing the occurrence of problems caused by moisture (specifically, the occurrence of dark spots and the decrease in light-emitting properties such as brightness and light-emitting efficiency). 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.

[0089] According to the present disclosure described above, the following means are provided. [Means 1] A sealant for an organic electroluminescence device, comprising [A] a polymerizable compound and [B] a polymerization initiator, and having a viscosity of 1 mPa s or more and 40 mPa s or less as measured at 25°C and 20 rpm using an E-type viscometer, wherein the polymerizable compound [A] is a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group. [Means 2] The sealant for an organic EL device according to [Means 1], wherein the fluorinated hydrocarbon group is a chain fluorinated hydrocarbon group. [Measure 3] The sealant for an organic EL device according to [Measure 2], wherein the fluorinated chain hydrocarbon group has two or more carbon atoms and has a carbon-carbon unsaturated bond. [Means 4] The fluorinated chain hydrocarbon group is "-C m F 2m-1 ", -Cn F 2n H" or "-C n F 2n+1 (wherein m is an integer of 2 or more, and n is an integer of 1 or more). [Means 5] The sealant for an organic EL device according to any one of [Means 1] to [Means 4], wherein the polymerizable group possessed by the polymerizable compound (A) is a cationically polymerizable group. [Measure 6] The sealant for an organic EL device according to any one of [Measure 1] to [Measure 4], wherein the polymerizable group possessed by the polymerizable compound [A] is a radically polymerizable group. [Measure 7] The sealant for an organic EL device according to any one of [Measures 1] to [Measures 4], wherein the polymerizable group contained in the compound (A1) is an oxetanyl group, an oxiranyl group, a vinyl ether group or a (meth)acryloyl group. [Means 8] The sealant for an organic EL device according to [Means 1], [Means 2] or [Means 7], wherein the compound (A1) is represented by the above formula (1). [Means 9] The sealant for an organic EL device according to any one of [Means 1] to [Means 8], further comprising, as the polymerizable compound [A], a monofunctional polymerizable compound not having a fluorinated hydrocarbon group, and a polyfunctional polymerizable compound not having a fluorinated hydrocarbon group. [Means 10] The sealant for an organic EL device according to [Means 9], wherein a ratio of the monofunctional polymerizable compound to a total amount of the monofunctional polymerizable compound and the polyfunctional polymerizable compound is 5 parts by mass or more and 70 parts by mass or less. [Measures 11] The sealant for an organic EL device according to [Measures 9] or [Measures 10], wherein the polyfunctional polymerizable compound comprises a siloxane compound having two or more polymerizable groups. [Measure 12] The sealant for an organic EL device according to any one of [Measure 1] to [Measure 11], wherein the content of the organic solvent is from 0% by mass to 3% by mass. [Means 13] The sealant for an organic EL device according to any one of [Means 1] to [Means 12], which has a surface tension at 25° C. of 15 mN / m or more and 40 mN / m or less. [Means 14] The sealant for an organic EL device according to any one of [Means 1] to [Means 13], which is for inkjet coating. [Means 15] A cured film formed from the sealant for an organic EL device according to any one of [Means 1] to [Means 14]. [Measurement 16] An organic electroluminescence device having a light-emitting layer sealed with the cured film according to [Measurement 15]. [Means 17] A method for producing an organic EL element, comprising the steps of applying the sealant for an organic EL element according to any one of [Means 1] to [Means 14] to a light-emitting layer-forming surface of a substrate on which an organic light-emitting layer has been formed, and curing the sealant for an organic EL element by irradiating with radiation to form a sealing structure. [Measure 18] The method for producing an organic EL element according to [Measure 17], wherein the sealant for an organic EL element is applied to the surface on which the light-emitting layer is formed by inkjet coating. EXAMPLES

[0090] The present invention will be described in more 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 by weight unless otherwise specified.

[0091] 1. Compound synthesis [Synthesis Example 1] Synthesis of compound (A1-1) In a 2-liter separable flask equipped with a stirrer, a cooler, and a dropping funnel, hexafluoropropene trimer (752 g, 1.67 mol), potassium carbonate (58.3 g, 0.42 mol), and methylene chloride (125 g, 1.46 mol) were placed and uniformly stirred, and then tetra-n-butylammonium bromide (1.1 g, 0.003 mol, manufactured by Wako Pure Chemical Industries, Ltd.) was added as a phase transfer catalyst. Next, a mixed solution of 3-ethyl-3-oxetanemethanol (95.7 g, 0.83 mol, manufactured by Toagosei Co., Ltd.) and methylene chloride (125 g, 1.46 mol) that had been prepared in advance was dropped into the separable flask at room temperature (25° C.). After the dropwise addition was completed, the temperature inside the separable flask was kept at 35° C. using an oil bath and heating was continued for 4 hours to obtain a reaction liquid of hexafluoropropene dimer and 3-ethyl-3-oxetanemethanol. The resulting reaction solution was cooled in air, the potassium carbonate was filtered off, and water (500 g) was added and vigorously shaken to separate into an aqueous layer and an organic layer. The organic layer was then collected and dried using magnesium sulfate (20 g, 0.17 mol), and the methylene chloride was then distilled off under reduced pressure. The product was then vacuum distilled (temperature 85°C, pressure 3 mmHg) to obtain a purified product in the form of a colorless, transparent liquid. The yield of the purified product (a fluorine-containing oxetane compound, a compound represented by the following formula (A1-1)) was 95%.

[0092] [Synthesis Example 2] Synthesis of compound (A1-2) In a three-neck flask (3 L) equipped with a dropping funnel, 259.5 g (1.8 mol) of 4-hydroxybutyl acrylate, 218.6 g (2.16 mol) of triethylamine, and 1000 g of acetonitrile were placed. Hexafluoropropene trimer (973.0 g, 2.16 mol) was placed in the dropping funnel and gradually dropped into the solution in the flask over a period of about 60 minutes while stirring. After the dropping was completed, stirring was continued at room temperature for another 3 hours. The reaction mixture was added with 2200 g of 1N hydrochloric acid to terminate the reaction, and then transferred to a 5 L beaker and washed three times with 1 L of water. The solution after the water washing treatment was dehydrated under reduced pressure to obtain 964.0 g (yield 93%) of a fluorine-containing acrylate compound represented by the following formula (A1-2). [ka]

[0093] 2. Preparation of encapsulant for organic electroluminescence devices The types and abbreviations of the polymerizable compound (A1), the polymerizable compound (A2), the polymerization initiator (B), and the surfactant (C) used in the preparation of the sealant for an organic EL device are shown below. <Polymerizable compound (A1)> (A1-1): A compound represented by the above formula (A1-1) (A1-2): A compound represented by the above formula (A1-2) <Polymerizable compound (A2)> (A2-1): 3-ethyl-3-(((3-ethyloxetan-3-yl)methoxy)methyl)oxetane (A2-2): 3-ethyl-3-((2-ethylhexyloxy)methyl)oxetane (A2-3): Epoxy group-containing bifunctional linear siloxane compound, product name "X-40-2669", manufactured by Shin-Etsu Chemical Co., Ltd. (A2-4): Tricyclodecane dimethanol diacrylate, product name "NK Ester A-DCP", manufactured by Shin-Nakamura Chemical Co., Ltd. (A2-5): 1,10-decanediol diacrylate, product name "NK Ester DOD", manufactured by Shin-Nakamura Chemical Co., Ltd. (A2-6): Lauryl acrylate (A2-7): Multifunctional acrylate, product name "Aronix M-313", manufactured by Toagosei Co., Ltd. <Polymerization initiator (B)> (B-1): Photocationic polymerization initiator, product name "CPI-410B" (manufactured by San-Apro Co., Ltd.) (B-2): 2,4,6-trimethylbenzoyldiphenylphosphine oxide (photoradical polymerization initiator, trade name "Irgacure TPO" (BASF)) <Surfactant (C)> (C-1): Fluorosurfactant, product name "F-563" (DIC Corporation) (C-2): Fluorosurfactant, product name "F-554" (manufactured by DIC Corporation) (C-3): Fluorine-based surfactant, trade name "Futergent DFX-18" (manufactured by Neos Co., Ltd.)

[0094] [Example 1] 1 part by mass of compound (A1-1), 40 parts by mass of compound (A2-1), 39 parts by mass of compound (A2-2), 20 parts by mass of compound (A2-3), and 2 parts by mass of polymerization initiator (B-1) were added, mixed and stirred, and then filtered using a 0.2 μm filter to prepare a sealant for organic EL devices.

[0095] [Examples 2 to 4, Comparative Examples 1 to 6] Sealant for organic EL devices of Examples 2 to 4 and Comparative Examples 1 to 6 were prepared in the same manner as in Example 1, except that the types and amounts (parts by mass) of each component were used as shown in Table 1. Examples 1 to 3 and Comparative Examples 1 to 5 are cationic polymerizable sealants, and Example 4 and Comparative Example 6 are radically polymerizable sealants.

[0096] 3. Evaluation The sealants for organic EL devices of Examples 1 to 4 and Comparative Examples 1 to 6 were measured for viscosity and surface tension, and were also evaluated for coatability by inkjet coating, wetting and spreading properties, and straightness of the film edge. The measurement and evaluation methods were as follows. The evaluation results are shown in Table 1.

[0097] <Viscosity measurement> The viscosity (mPa·s) of the sealant for organic EL devices was measured at 25°C and 20 rpm using an E-type viscometer (RE-85L, manufactured by Toki Sangyo Co., Ltd.).

[0098] <Surface tension measurement> The surface tension of the sealant for organic EL devices at 25° C. was measured by the Wilhelmy method using a surface tensiometer DY-700 manufactured by Kyowa Interface Science Co., Ltd.

[0099] <Cured film formation and inkjet coating evaluation> A SiNx film was formed on a glass substrate with a thickness of 100 nm (film formation conditions) to prepare a substrate for evaluation. A sealant for organic EL elements was ink-jet-discharged from the ink-jet head of a piezoelectric ink-jet printer at a pitch of 40 μm x 40 μm onto this substrate for evaluation, to prepare a coating film of 3 cm square. After 5 minutes, a 395 nm LED lamp was used to apply an exposure dose of 3000 mJ / cm. 2 The coating film was cured by irradiating it with ultraviolet light at 1000 rpm. The voltage of the inkjet head was adjusted so that the amount of one ink dot discharged was 12 pL. The inner part of the end of the obtained cured film was observed visually and with a microscope (5x), and the inkjet coating property, inkjet wetting spreadability, and inkjet end straightness were evaluated according to the following criteria. -Evaluation of inkjet coating properties A: No uncoated areas are observed by visual inspection. B: Uncoated areas are visually observed. -Evaluation of inkjet wetting and spreading properties A: The size of the cured film is 3.5cm square or more. B: The size of the cured film is 2.5 cm square or more and less than 3.5 cm square. C: The size of the cured film is less than 2.5 cm square. -Evaluation of inkjet edge straightness A: No dendrites were observed at the edge of the cured film under a microscope. B: Dendritic areas are observed at the edge of the cured film under a microscope.

[0100] [Table 1]

[0101] As shown in Table 1, the sealants for organic EL devices of Examples 1 to 4 had little coating unevenness and good wetting and spreading properties when applied to a substrate by an inkjet method. In addition, the edge lines on both the left and right sides of the cured film were almost parallel to the scanning direction of the inkjet nozzle, and the straightness of the end portions was maintained.

[0102] In contrast, the sealants for organic EL devices of Comparative Examples 1 to 6, in which a fluorine-based surfactant was blended instead of the polymerizable compound (A1), suppressed the occurrence of coating unevenness in inkjet coating, but were inferior to Examples 1 to 4 in wetting and spreading properties, straightness of the film edge, or both.

[0103] From the above results, it is clear that a sealant for an organic EL device containing a compound having a polymerizable group and a monovalent fluorinated hydrocarbon group as the polymerizable compound [A] can improve the wetting and spreading properties and the straightness of the film edge in a well-balanced manner when applied to a substrate by inkjet coating.

Claims

1. [A] a polymerizable compound and [B] a polymerization initiator, The viscosity measured using an E-type viscometer at 25° C. and 20 rpm is 1 mPa·s or more and 40 mPa·s or less, The polymerizable compound [A] includes a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group, the fluorinated hydrocarbon group is a fluorinated chain hydrocarbon group, The fluorinated chain hydrocarbon group has two or more carbon atoms and has a carbon-carbon unsaturated bond.

2. [A] a polymerizable compound and [B] a polymerization initiator, The viscosity measured using an E-type viscometer at 25° C. and 20 rpm is 1 mPa·s or more and 40 mPa·s or less, The polymerizable compound [A] includes a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group, the fluorinated hydrocarbon group is a fluorinated chain hydrocarbon group, The fluorinated chain hydrocarbon group is represented by "-CmF2m-1", "-CnF2nH" or "-CnF2n+1" (wherein m is an integer of 2 or more, and n is an integer of 1 or more).

3. [A] a polymerizable compound and [B] a polymerization initiator, The viscosity measured using an E-type viscometer at 25° C. and 20 rpm is 1 mPa·s or more and 40 mPa·s or less, The polymerizable compound [A] includes a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group, The compound (A1) is a sealant for an organic EL element represented by the following formula (1). 【Chemistry 1】 (In formula (1), X １ Y is a monovalent group having an oxetanyl group, an oxiranyl group, a vinyl ether group, or a (meth)acryloyl group. １ R is a divalent group containing -O- between the carbon-carbon bonds of an alkanediyl group having 1 to 10 carbon atoms or an alkanediyl group having 2 to 10 carbon atoms. ｆ "-C ｍ F ２ｍ－１ ", -C ｎ F ２ｎ H" or "-C ｎ F ２ｎ＋１ " m is an integer of 2 or more, and n is an integer of 1 or more.

4. [A] a polymerizable compound and [B] a polymerization initiator, The viscosity measured using an E-type viscometer at 25° C. and 20 rpm is 1 mPa·s or more and 40 mPa·s or less, The polymerizable compound [A] includes a compound (A1) having a polymerizable group and a monovalent fluorinated hydrocarbon group, The sealant for an organic EL device further contains, as the polymerizable compound (A), a monofunctional polymerizable compound not having a fluorinated hydrocarbon group, and a polyfunctional polymerizable compound not having a fluorinated hydrocarbon group.

5. 5. The sealant for an organic EL element according to claim 4, wherein a ratio of the monofunctional polymerizable compound to a total amount of the monofunctional polymerizable compound and the polyfunctional polymerizable compound is 5 parts by mass or more and 70 parts by mass or less.

6. The sealant for an organic EL element according to claim 4 , wherein the polyfunctional polymerizable compound comprises a siloxane compound having two or more polymerizable groups.

7. The sealant for an organic EL element according to claim 1 , wherein the polymerizable group of the polymerizable compound (A) is a cationically polymerizable group.

8. The sealant for an organic EL element according to claim 1 , wherein the polymerizable group of the polymerizable compound (A) is a radically polymerizable group.

9. 3. The sealant for an organic EL device according to claim 1, wherein the polymerizable group contained in the compound (A1) is an oxetanyl group, an oxiranyl group, a vinyl ether group, or a (meth)acryloyl group.

10. 3. The sealant for an organic EL device according to claim 1, wherein the content of the organic solvent is from 0% by mass to 3% by mass.

11. 3. The sealant for an organic EL device according to claim 1, which has a surface tension at 25° C. of 15 mN / m or more and 40 mN / m or less.

12. The sealant for an organic EL device according to claim 1 or 2, which is for inkjet coating.

13. A cured film formed from the sealant for an organic electroluminescence device according to any one of claims 1 to 6.

14. An organic electroluminescence element having a light-emitting layer sealed with the cured film according to claim 13.

15. 7. A method for producing an organic EL element, comprising the steps of: applying the sealant for an organic EL element according to any one of claims 1 to 6 to a light-emitting layer-forming surface of a substrate on which an organic light-emitting layer is formed; and curing the sealant for an organic EL element by irradiating with radiation to form a sealing structure.

16. The method for producing an organic EL element according to claim 15, wherein the sealant for an organic EL element is applied to the surface on which the light-emitting layer is formed by inkjet coating.

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