Sealant for organic EL display elements

Abstract

The purpose of the present invention is to provide a sealant for an organic EL display element with which it is possible to obtain an organic EL display element that has exceptional moisture prevention and adhesiveness and that also has exceptional reliability. The present invention is a sealant for an organic EL display element that contains a curable resin and a water-absorbent filler, the sealant being such that: the curable resin contains a (meth) acrylic compound that does not have an isocyanate group or a blocked isocyanate group, and an isocyanate compound or a blocked isocyanate; and the content ratio of the water-absorbent filler is 20 wt% or greater.

Description

[Technical Field]

[0001] The present invention relates to a sealant for an organic EL display element that is excellent in moisture permeation prevention property and adhesiveness, and that can provide an organic EL display element that is excellent in reliability. [Background technology]

[0002] An organic electroluminescent display element (organic EL display element) has a thin film structure in which an organic light-emitting material layer is sandwiched between a pair of opposing electrodes. Electrons are injected into this organic light-emitting material layer from one electrode, and holes are injected from the other electrode, causing the electrons and holes to combine within the organic light-emitting material layer, resulting in self-luminescence. Compared to liquid crystal display elements and other elements that require a backlight, organic EL display elements have the advantages of better visibility, thinner designs, and the ability to be driven by a low DC voltage.

[0003] However, such organic EL display elements have a problem in that when the organic light-emitting material layer or electrodes are exposed to the outside air, their light-emitting characteristics rapidly deteriorate, shortening their lifespan. Therefore, in order to improve the stability and durability of organic EL display elements, sealing technology that isolates the organic light-emitting material layer and electrodes from moisture and oxygen in the air is essential.

[0004] Patent Document 1 discloses a method for sealing an organic EL display element by using a structure including an organic filling layer that covers and seals a laminate having an organic light-emitting material layer, and a moisture-absorbing sealing layer (sealing wall) that covers the side surface of the organic filling layer. Typically, as a sealant for an organic EL display element, an in-plane sealant is used for the organic filling layer, and a peripheral sealant having a different component from the in-plane sealant is used for the sealing wall. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-67598 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a sealant for an organic EL display element that is excellent in moisture permeation prevention property and adhesiveness, and that can provide an organic EL display element that is excellent in reliability. [Means for solving the problem]

[0007] The present invention provides a sealant for an organic EL display element, which contains a curable resin and a water-absorbing filler, wherein the curable resin contains a (meth)acrylic compound that does not have an isocyanate group or a blocked isocyanate group, and an isocyanate compound or a blocked isocyanate, and the content of the water-absorbing filler is 20% by weight or more. The present invention will be described in detail below.

[0008] The present inventors have investigated thinning the sealing wall in order to ensure a wide display area of ​​an organic EL display element. However, when a peripheral sealant is applied with a narrower line width (thinner line width) to thin the sealing wall, sufficient adhesive strength is not obtained, and the resulting organic EL display element may have poor reliability. In particular, when a large amount of water-absorbent filler is blended into the peripheral sealant to improve moisture permeation resistance, the adhesiveness significantly decreases under high-temperature and high-humidity environments. Therefore, the present inventors have investigated a sealant for an organic EL display element containing a large amount of water-absorbent filler, which contains, as a curable resin, a (meth)acrylic compound having no isocyanate group or blocked isocyanate group, and an isocyanate compound or blocked isocyanate. As a result, they have found that the resulting sealant for an organic EL display element has excellent moisture permeation resistance and adhesiveness, and can provide an organic EL display element with excellent reliability, thereby completing the present invention.

[0009] The sealant for an organic EL display element of the present invention contains a curable resin. The curable resin contains a (meth)acrylic compound having no isocyanate group and no blocked isocyanate group. By containing the (meth)acrylic compound having no isocyanate group and no blocked isocyanate group, the sealant for an organic EL display element of the present invention has excellent curability. In this specification, the term "(meth)acrylic" means acrylic or methacrylic, the term "(meth)acrylic compound" means a compound having a (meth)acryloyl group, and the term "(meth)acryloyl" means acryloyl or methacryloyl.

[0010] Examples of the (meth)acrylic compound having no isocyanate group or blocked isocyanate group include urethane (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, methylcyclohexyl (meth)acrylate, norbornylmethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, cyclodecyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 2-hydroxyisopropyl (meth)acrylate. Among these, the (meth)acrylic compound having no isocyanate group and no blocked isocyanate group preferably contains a (meth)acrylic compound having an alicyclic skeleton from the viewpoint of further improving the adhesiveness and moisture-proofing properties of the resulting sealant for organic EL display elements and from the viewpoint of improving compatibility with polyolefins, which will be described later. Furthermore, the (meth)acrylic compound having no isocyanate group and no blocked isocyanate group preferably contains a polyfunctional (meth)acrylic compound from the viewpoint of further improving the adhesiveness (particularly the adhesiveness under high-temperature and high-humidity environments) of the resulting sealant for organic EL display elements. In this specification, the term "(meth)acrylate" refers to an acrylate or methacrylate, and the term "urethane (meth)acrylate" refers to a compound having a urethane bond and a (meth)acryloyl group. The term "polyfunctional (meth)acrylic compound" refers to a compound having two or more (meth)acryloyl groups in one molecule.

[0011] The preferred lower limit of the content of the (meth)acrylic compound having no isocyanate group or blocked isocyanate group per 100 parts by weight of the total curable resin is 0.01 parts by weight, and the preferred upper limit is 99.99 parts by weight. When the content of the (meth)acrylic compound having no isocyanate group or blocked isocyanate group is within this range, the resulting sealant for organic EL display elements has better adhesion and storage stability. The more preferred lower limit of the content of the (meth)acrylic compound having no isocyanate group or blocked isocyanate group is 0.1 parts by weight, even more preferred lower limit is 10 parts by weight, even more preferred lower limit is 20 parts by weight, and particularly preferred lower limit is 80 parts by weight.

[0012] The curable resin contains an isocyanate compound or a blocked isocyanate. By containing the isocyanate compound or the blocked isocyanate and by controlling the content of the water-absorbing filler described below within the range described below, the sealant for an organic EL display element of the present invention has excellent adhesiveness (particularly adhesiveness under high-temperature and high-humidity environments), and the resulting organic EL display element has excellent reliability.

[0013] The isocyanate compound or the blocked isocyanate may or may not have a (meth)acryloyl group, and preferably has a (meth)acryloyl group from the viewpoint of further improving the adhesiveness (particularly adhesiveness under high-temperature and high-humidity environments) and storage stability of the resulting sealant for an organic EL display element.

[0014] Examples of the isocyanate compound having a (meth)acryloyl group include 2-(meth)acryloyloxyethyl isocyanate, 1,1-(bis(meth)acryloyloxymethyl)ethyl isocyanate, etc. Among these, 2-(meth)acryloyloxyethyl isocyanate is preferred.

[0015] Examples of the blocked isocyanate having a (meth)acryloyl group include 2-((3,5-dimethylpyrazolyl)carbonylamino)ethyl (meth)acrylate, 2-(O-(1'-methylpropylideneamino)carboxyamino)ethyl (meth)acrylate, and 2-(O-(1'-methylpropylideneamino)carboxyamino)(meth)acrylate. Of these, 2-((3,5-dimethylpyrazolyl)carbonylamino)ethyl (meth)acrylate is preferred.

[0016] Among the above-mentioned isocyanate compounds or the above-mentioned blocked isocyanates, examples of those not having the (meth)acryloyl group include aromatic isocyanates, aliphatic isocyanates having an aromatic ring, aliphatic isocyanates not having an aromatic ring, and alicyclic isocyanates. Examples of the aromatic isocyanate include tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, polymers of methylene diphenyl diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate. Examples of the aliphatic isocyanate having an aromatic ring include α,α,α',α'-tetramethylxylylene diisocyanate. Examples of the aliphatic isocyanate having no aromatic ring include methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate. Examples of the alicyclic isocyanate include cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), and isopropylidenedicyclohexyl diisocyanate. Among these, methylene diphenyl diisocyanate and polymers of methylene diphenyl diisocyanate are preferred from the viewpoint of adhesiveness.

[0017] As the isocyanate compound or the blocked isocyanate, the isocyanate compound is preferred from the viewpoint of adhesiveness, and the blocked isocyanate is preferred from the viewpoint of storage stability.

[0018] The preferred lower limit of the content of the isocyanate compound or the blocked isocyanate per 100 parts by weight of the total curable resin is 0.05 parts by weight, and the preferred upper limit is 8 parts by weight. By ensuring that the content of the isocyanate compound or the blocked isocyanate is within this range, the resulting sealant for organic EL display elements will have superior adhesion (particularly adhesion under high-temperature, high-humidity environments) and storage stability. The more preferred lower limit of the content of the isocyanate compound or the blocked isocyanate is 0.1 parts by weight, and the more preferred upper limit is 5 parts by weight.

[0019] The curable resin may contain other curable resins in addition to the (meth)acrylic compound having no isocyanate group or no blocked isocyanate group, and the isocyanate compound or the blocked isocyanate.

[0020] Examples of the other curable resins include epoxy compounds, oxetane compounds, and urethane compounds having no (meth)acryloyl group.

[0021] Examples of the epoxy compound include glycidyl ether compounds and alicyclic epoxy compounds. Examples of the glycidyl ether compound include diethylene glycol diglycidyl ether. Examples of the alicyclic epoxy compound include 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate and 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol.

[0022] Examples of the oxetane compound include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, di[2-(3-oxetanyl)butyl]ether, and 3-ethyl-3-hydroxymethyloxetane.

[0023] Examples of the urethane compound not having a (meth)acryloyl group include a reaction product of an isocyanate compound and an arbitrary polyol compound. Examples of the isocyanate compound include a toluene diisocyanate compound and a diphenylmethane diisocyanate compound. Examples of the toluene diisocyanate compound include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate, and mixtures thereof. Examples of the diphenylmethane diisocyanate compound include 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and mixtures thereof.

[0024] When the curable resin contains a blocked isocyanate, it is preferable that the curable resin further contains an amine compound, which can gradually convert the blocked isocyanate into an isocyanate, thereby improving both storage stability and adhesiveness. The amine compound may, for example, be 1,4-diazabicyclo[2.2.2]octane. The amount of the amine compound added is preferably 1 part by weight or more and 20 parts by weight or less per 100 parts by weight of the blocked isocyanate.

[0025] The sealant for an organic EL display element of the present invention contains a water-absorbing filler. By containing the water-absorbing filler, the sealant for an organic EL display element of the present invention has excellent moisture permeation prevention properties.

[0026] Examples of the water-absorbing filler include alkaline earth metal oxides, magnesium oxide, and molecular sieves. Examples of the alkaline earth metal oxides include calcium oxide, strontium oxide, and barium oxide. Among these, from the viewpoint of water absorption, alkaline earth metal oxides are preferred, and calcium oxide is more preferred. These water-absorbing fillers may be used alone or in combination of two or more.

[0027] The lower limit of the content of the water-absorbing filler in the sealant for organic EL display elements of the present invention is 20% by weight. When the content of the water-absorbing filler is 20% by weight or more, the sealant for organic EL display elements of the present invention has excellent moisture-proofing properties. Furthermore, when the sealant for organic EL display elements of the present invention contains the isocyanate compound or the blocked isocyanate, it has excellent adhesion (particularly adhesion under high-temperature and high-humidity environments) even when a large amount of the water-absorbing filler is blended, and the resulting organic EL display element has excellent reliability. The lower limit of the content of the water-absorbing filler is preferably 30% by weight, and more preferably 40% by weight. From the viewpoint of application properties, the upper limit of the content of the water-absorbing filler is preferably 70% by weight, and more preferably 60% by weight.

[0028] The sealant for an organic EL display element of the present invention may contain other fillers in addition to the water-absorbing filler as long as the object of the present invention is not impaired. As the other filler, inorganic fillers and organic fillers can be used. Examples of the inorganic filler include silica, talc, and alumina. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, acrylic polymer fine particles, etc. Among these, talc is preferred.

[0029] The sealant for an organic EL display element of the present invention preferably contains a polyolefin. By containing the polyolefin, the sealant for an organic EL display element of the present invention has better moisture permeation prevention properties.

[0030] From the viewpoint of further improving moisture permeation prevention properties, the polyolefin preferably contains at least one selected from the group consisting of polyisobutylene, polybutene, and polybutadiene, and more preferably contains polyisobutylene. The above polyolefins may be used alone or in combination of two or more kinds.

[0031] The weight-average molecular weight of the polyolefin preferably has a lower limit of 10,000 and an upper limit of 400,000. When the weight-average molecular weight of the polyolefin is within this range, the resulting sealant for an organic EL display device has better coatability, adhesiveness, and moisture-proofing properties. The weight-average molecular weight of the polyolefin more preferably has a lower limit of 20,000 and an upper limit of 70,000. In this specification, the "weight average molecular weight" is a value determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted into polystyrene. Examples of columns used in measuring the weight average molecular weight converted into polystyrene by GPC include Shodex LF-804 (manufactured by Showa Denko KK).

[0032] The preferred lower limit of the polyolefin content per 100 parts by weight of the total of the curable resin and the polyolefin is 10 parts by weight, and the preferred upper limit is 80 parts by weight. When the polyolefin content is 10 parts by weight or more, the resulting sealant for organic EL display elements has better moisture permeation prevention properties. When the polyolefin content is 80 parts by weight or less, the resulting sealant for organic EL display elements has better coatability and adhesiveness. The more preferred lower limit of the polyolefin content is 20 parts by weight, and the more preferred upper limit is 60 parts by weight.

[0033] The sealant for an organic EL display element of the present invention may contain a tackifier resin for the purpose of further improving adhesiveness. Examples of the tackifying resin include terpene resins, modified terpene resins, coumarone resins, indene resins, and petroleum resins. Examples of the modified terpene resin include hydrogenated terpene resin, terpene-phenol copolymer resin, and aromatic modified terpene resin. Examples of the petroleum resin include aliphatic petroleum resins, hydrogenated alicyclic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, alicyclic petroleum resins, dicyclopentadiene petroleum resins, and hydrogenated products thereof. Among these, from the viewpoint of the adhesiveness, moisture resistance, compatibility, etc. of the sealant for organic EL display elements, preferred tackifier resins are terpene resins, aromatic-modified terpene resins, terpene-phenol copolymer resins, hydrogenated alicyclic petroleum resins, aromatic petroleum resins, aliphatic-aromatic copolymer petroleum resins, and alicyclic petroleum resins, with alicyclic petroleum resins being more preferred, alicyclic saturated hydrocarbon resins and alicyclic unsaturated hydrocarbon resins being even more preferred, and cyclohexyl ring-containing saturated hydrocarbon resins and dicyclopentadiene-modified hydrocarbon resins being particularly preferred. These tackifier resins may be used alone or in combination of two or more.

[0034] The content of the tackifier resin is preferably 0.01 parts by weight at the lower limit and 100 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). By having the content of the tackifier resin within this range, the effect of improving adhesion while maintaining moisture barrier properties can be more effectively exhibited. The more preferred lower limit of the content of the tackifier resin is 0.2 parts by weight, and the more preferred upper limit is 20 parts by weight.

[0035] The sealant for an organic EL display element of the present invention preferably contains a polymerization initiator. The polymerization initiator may be a radical polymerization initiator or a cationic polymerization initiator, with the radical polymerization initiator being preferred.

[0036] Examples of the radical polymerization initiator include a photoradical polymerization initiator and a thermal radical polymerization initiator.

[0037] Examples of the photoradical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, and thioxanthone compounds. Specific examples of the photoradical polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 1,2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4-(4-morpholinyl)phenyl)-1-butanone, 2,2-dimethoxy-2-phenylacetophenone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl- Examples include 1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 1-(4-(2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-(phenylthio)phenyl)-1,2-octanedione 2-(O-benzoyloxime), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether.

[0038] Examples of the thermal radical polymerization initiator include azo compounds, organic peroxides, and the like. Examples of the azo compound include 2,2'-azobis(2,4-dimethylvaleronitrile) and azobisisobutyronitrile. Examples of the organic peroxide include benzoyl peroxide, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, and peroxydicarbonate.

[0039] Among the above thermal radical polymerization initiators, commercially available ones include, for example, VPE-0201, VPE-0401, VPE-0601, VPS-0501, VPS-1001, and V-501 (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0040] Examples of the cationic polymerization initiator include a photo-cationic polymerization initiator and a thermal cationic polymerization initiator.

[0041] The photocationic polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid upon irradiation with light, and may be either an ionic photoacid generating type or a nonionic photoacid generating type.

[0042] The anion moiety of the ionic photoacid generating cationic photopolymerization initiator is, for example, BF4 - , PF6 - , SbF6 - , or (BX4) - (wherein X represents a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups), etc. Examples of the ionic photoacid-generating photocationic polymerization initiator include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, and (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salts, each of which has the anion moiety.

[0043] Examples of the aromatic sulfonium salt include bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(diphenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(diphenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, diphenyl-4-(phenylthio)phenylsulfonium tetrakis(pentafluorophenyl)borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate,

[0033] Examples of sulfonium tetrakis(pentafluorophenyl)borate include triarylsulfonium tetrakis(pentafluorophenyl)borate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, and tris(4-(4-acetylphenyl)thiophenyl)sulfonium tetrakis(pentafluorophenyl)borate.

[0044] Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluorophosphate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluoroantimonate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrafluoroborate, and 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrakis(pentafluorophenyl)borate.

[0045] Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis(pentafluorophenyl)borate.

[0046] Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2-cyanopyridinium tetrakis(pentafluorophenyl)borate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluorophosphate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluoroantimonate, 1-(naphthylmethyl)-2-cyanopyridinium tetrafluoroborate, and 1-(naphthylmethyl)-2-cyanopyridinium tetrakis(pentafluorophenyl)borate.

[0047] Examples of the (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salt include (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluorophosphate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluoroantimonate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrafluoroborate, and (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrakis(pentafluorophenyl)borate.

[0048] Examples of the nonionic photoacid-generating cationic photopolymerization initiator include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenolsulfonic acid esters, diazonaphthoquinone, and N-hydroxyimide sulfonates.

[0049] Among the above-mentioned cationic photopolymerization initiators, commercially available ones include, for example, cationic photopolymerization initiators manufactured by Midori Chemical Industry Co., Ltd., cationic photopolymerization initiators manufactured by Union Carbide Corporation, cationic photopolymerization initiators manufactured by ADEKA Corporation, cationic photopolymerization initiators manufactured by 3M Corporation, cationic photopolymerization initiators manufactured by BASF Corporation, and cationic photopolymerization initiators manufactured by Rhodia Corporation. Examples of the cationic photopolymerization initiators manufactured by Midori Chemical Co., Ltd. include DTS-200. Examples of the cationic photopolymerization initiators manufactured by Union Carbide include UVI6990 and UVI6974. Examples of the cationic photopolymerization initiators manufactured by ADEKA Corporation include SP-150 and SP-170. Examples of the cationic photopolymerization initiator manufactured by 3M include FC-508 and FC-512. Examples of the cationic photopolymerization initiators manufactured by BASF include IRGACURE261 and IRGACURE290. Examples of the cationic photopolymerization initiators manufactured by Rhodia include PI2074.

[0050] The thermal cationic polymerization initiator has an anion moiety of BF4 - , PF6 - , SbF6 - , or (BX4) - (wherein X represents a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups), sulfonium salts, phosphonium salts, ammonium salts, etc. are preferred. Of these, sulfonium salts and ammonium salts are preferred.

[0051] Examples of the sulfonium salt include triphenylsulfonium tetrafluoroborate and triphenylsulfonium hexafluoroantimonate.

[0052] Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantimonate and tetrabutylphosphonium hexafluoroantimonate.

[0053] Examples of the ammonium salts include dimethylphenyl(4-methoxybenzyl)ammonium hexafluorophosphate, dimethylphenyl(4-methoxybenzyl)ammonium hexafluoroantimonate, dimethylphenyl(4-methoxybenzyl)ammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(4-methylbenzyl)ammonium hexafluorophosphate, dimethylphenyl(4-methylbenzyl)ammonium hexafluoroantimonate, dimethylphenyl(4-methylbenzyl)ammonium hexafluorotetrakis(pentafluorophenyl)borate, and methylphenyldibenzylammonium hexafluorophosphate. , methylphenyldibenzylammonium hexafluoroantimonate, methylphenyldibenzylammonium tetrakis(pentafluorophenyl)borate, phenyltribenzylammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(3,4-dimethylbenzyl)ammonium tetrakis(pentafluorophenyl)borate, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-diethyl-N-benzylanilinium tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N,N-diethyl-N-benzylpyridinium trifluoromethanesulfonate, and the like.

[0054] Among the above-mentioned thermal cationic polymerization initiators, commercially available ones include, for example, thermal cationic polymerization initiators manufactured by Sanshin Chemical Industry Co., Ltd. and thermal cationic polymerization initiators manufactured by King Industries. Examples of the thermal cationic polymerization initiators manufactured by Sanshin Chemical Industry Co., Ltd. include San-Aid SI-60, San-Aid SI-80, San-Aid SI-B3, San-Aid SI-B3A, and San-Aid SI-B4. Examples of the thermal cationic polymerization initiators manufactured by King Industries include CXC-1612 and CXC-1821.

[0055] The content of the polymerization initiator is preferably 0.05 parts by weight at the lower limit and 10 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). When the content of the polymerization initiator is 0.05 parts by weight or more, the resulting sealant for organic EL display elements has superior curability. When the content of the polymerization initiator is 10 parts by weight or less, the curing reaction of the resulting sealant for organic EL display elements does not become too fast, resulting in superior workability and a more uniform cured product. The lower limit of the content of the polymerization initiator is more preferably 1 part by weight, and the upper limit is more preferably 3 parts by weight.

[0056] The sealant for an organic EL display element of the present invention may contain a sensitizer. The sensitizer has the role of further improving the polymerization initiation efficiency of the polymerization initiator and further accelerating the curing reaction of the sealant for an organic EL display element of the present invention.

[0057] Examples of the sensitizer include anthracene compounds, thioxanthone compounds, 2,2-dimethoxy-1,2-diphenylethan-1-one, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide. Examples of the anthracene compounds include 9,10-dibutoxyanthracene. Examples of the thioxanthone compounds include 2,4-diethylthioxanthone. These sensitizers may be used alone or in combination of two or more.

[0058] The content of the sensitizer is preferably 0.05 parts by weight at the lower limit and 3 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). When the content of the sensitizer is 0.05 parts by weight or more, the sensitizing effect is more pronounced. When the content of the sensitizer is 3 parts by weight or less, light can be transmitted to deep areas without excessive absorption. A more preferred lower limit of the content of the sensitizer is 0.1 parts by weight, and a more preferred upper limit is 1 part by weight.

[0059] The sealant for an organic EL display element of the present invention may contain a heat curing agent. Examples of the heat curing agent include hydrazide compounds, imidazole derivatives, acid anhydrides, dicyandiamide, guanidine derivatives, modified aliphatic polyamines, and addition products of various amines and epoxy resins.

[0060] Examples of the hydrazide compound include 1,3-bis(hydrazinocarboethyl)-5-isopropylhydantoin, sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, and malonic acid dihydrazide. Examples of the imidazole derivatives include 1-cyanoethyl-2-phenylimidazole, N-(2-(2-methyl-1-imidazolyl)ethyl)urea, 2,4-diamino-6-(2'-methylimidazolyl-(1'))-ethyl-s-triazine, N,N'-bis(2-methyl-1-imidazolylethyl)urea, N,N'-(2-methyl-1-imidazolylethyl)-adipamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2-phenyl-4,5-dihydroxymethylimidazole. Examples of the acid anhydride include tetrahydrophthalic anhydride and ethylene glycol bis(anhydrotrimellitate). These heat curing agents may be used alone or in combination of two or more.

[0061] Among the above-mentioned heat curing agents, commercially available ones include, for example, SDH (manufactured by Nippon Finechem Co., Ltd.), ADH (manufactured by Otsuka Chemical Co., Ltd.), Amicure VDH, Amicure VDH-J, and Amicure UDH (all manufactured by Ajinomoto Fine-Techno Co., Ltd.).

[0062] The content of the thermosetting agent is preferably 0.01 parts by weight at the lower limit and 10 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). When the content of the thermosetting agent is 0.01 parts by weight or more, the resulting sealant for an organic EL display element has better thermosetting properties. When the content of the thermosetting agent is 10 parts by weight or less, the resulting sealant for an organic EL display element has better storage stability. The lower limit of the content of the thermosetting agent is more preferably 0.5 parts by weight, and the upper limit is more preferably 5 parts by weight, and even more preferably 1 part by weight, and even more preferably 3 parts by weight.

[0063] The sealant for an organic EL display element of the present invention may contain a stabilizer. By containing the stabilizer, the sealant for an organic EL display element of the present invention has better storage stability.

[0064] Examples of the stabilizer include aromatic amine compounds, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and the like. Examples of the aromatic amine compound include benzylamine and aminophenol-type epoxy resin. Of these, aromatic amine compounds are preferred, and benzylamine is more preferred. These stabilizers may be used alone or in combination of two or more.

[0065] The content of the stabilizer is preferably 0.001 parts by weight at the lower limit and 2 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (or the total of the curable resin and the polyolefin when the polyolefin is contained). By using a stabilizer content within this range, the resulting sealant for an organic EL display element has excellent storage stability while maintaining excellent curability. The more preferred lower limit of the stabilizer content is 0.005 parts by weight, and the more preferred upper limit is 1 part by weight.

[0066] The sealant for an organic EL display element of the present invention may contain a silane coupling agent. The silane coupling agent plays a role in improving the adhesion between the sealant for an organic EL display element of the present invention and a substrate or the like.

[0067] Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-isocyanatopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more.

[0068] The content of the silane coupling agent is preferably 0.1 parts by weight at the lower limit and 10 parts by weight at the upper limit relative to 100 parts by weight of the curable resin (the total of the curable resin and the polyolefin when the polyolefin is contained). By using the silane coupling agent in this range, the bleed-out of excess silane coupling agent can be prevented, while the adhesiveness of the resulting sealant for organic EL display elements can be improved. The lower limit of the content of the silane coupling agent is more preferably 0.5 parts by weight, and the upper limit is more preferably 5 parts by weight.

[0069] The sealant for an organic EL display element of the present invention may contain a surface modifier within a range that does not impair the object of the present invention. By containing the surface modifier, the flatness of the coating film of the sealant for an organic EL display element of the present invention can be improved. Examples of the surface modifier include surfactants and leveling agents.

[0070] Examples of the surface modifier include silicone-based, acrylic-based, and fluorine-based agents. Among the above surface modifiers, commercially available ones include, for example, surface modifiers manufactured by BYK Japan, surface modifiers manufactured by Kusumoto Chemical Co., Ltd., and surface modifiers manufactured by AGC Seimi Chemical Co., Ltd. Examples of the surface modifiers manufactured by BYK Japan include BYK-300, BYK-302, and BYK-331. An example of the surface modifier manufactured by Kusumoto Chemicals Co., Ltd. is UVX-272. An example of the surface modifier manufactured by AGC Seimi Chemical Co., Ltd. is Surflon S-611.

[0071] The sealant for an organic EL display element of the present invention may contain a compound that reacts with the acid generated in the sealant for an organic EL display element and / or an ion exchange resin, as long as the object of the present invention is not impaired.

[0072] Examples of the compound that reacts with the generated acid include substances that neutralize the acid, such as carbonates or bicarbonates of alkali metals, or carbonates or bicarbonates of alkaline earth metals, etc. Specific examples include calcium carbonate, calcium bicarbonate, sodium carbonate, and sodium bicarbonate.

[0073] The ion exchange resin may be of the cation exchange type, anion exchange type, or amphoteric ion exchange type, but the cation exchange type or amphoteric ion exchange type capable of adsorbing chloride ions is particularly preferred.

[0074] The sealant for an organic EL display element of the present invention may contain various known additives, such as a curing retarder, a reinforcing agent, a softener, a plasticizer, a viscosity modifier, an ultraviolet absorber, and an antioxidant, as needed, within the scope of not impairing the object of the present invention.

[0075] The sealant for an organic EL display element of the present invention preferably does not contain a solvent from the viewpoint of further suppressing outgassing. The sealant for an organic EL display element of the present invention can have excellent coatability even without containing a solvent. In this specification, "solvent-free" means that the solvent content is less than 1000 ppm.

[0076] Examples of a method for producing the sealant for an organic EL display element of the present invention include a method of mixing, using a mixer, a polyolefin, a curable resin, a water-absorbing filler, and additives such as a polymerization initiator and / or a heat curing agent, and optionally a silane coupling agent. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mixer.

[0077] The sealant for organic EL display elements of the present invention has a viscosity of preferably 1000 Pa s or less, as measured at 25°C and 2.5 rpm using an E-type viscometer. Having a viscosity of 1000 Pa s or less ensures that the resulting sealant for organic EL display elements has excellent coatability. The more preferred upper limit of the viscosity is 500 Pa s. There is no particular preferred lower limit to the viscosity, but the substantial lower limit is 100 Pa·s.

[0078] The sealant for an organic EL display device of the present invention has a preferable lower limit of adhesive strength to glass of a cured product after storage for 500 hours in an environment of 85°C and 85% RH of 0.8 kgf / cm. 2 After storing the cured product in the above environment of 85°C and 85% RH for 500 hours, the adhesive strength to glass was 0.8 kgf / cm 2 Due to the above, the sealant for an organic EL display element of the present invention can be suitably used as a peripheral sealant for an organic EL display element. A more preferable lower limit of the adhesive strength to glass of the cured product after storage for 500 hours in an environment of 85°C and 85% RH is 1.2 kgf / cm. 2 is. There is no particular upper limit to the adhesive strength of the cured product to glass after storage for 500 hours in the above environment of 85°C and 85% RH, but the practical upper limit is 3.0 kgf / cm 2 is.

[0079] The cured product of the sealant for organic EL display elements of the present invention is preferably used as a sealing wall surrounding the peripheral portion of an organic EL display element. That is, the sealant for organic EL display elements of the present invention is preferably used as a peripheral sealant for organic EL display elements for forming a sealing wall around a laminate having an organic light-emitting material layer. The peripheral sealant for organic EL display elements is usually used in combination with an in-plane sealant for organic EL display elements that covers the laminate.

[0080] The sealing wall formed using the cured product of the sealant for organic EL display elements of the present invention preferably has a thickness in the line width direction of 5 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less, from the viewpoint of ensuring a wide display area of ​​the resulting organic EL display element. Because the sealant for organic EL display elements of the present invention has excellent moisture permeation prevention properties, adhesion, and reliability, the thickness of the sealing wall can be set to the above-mentioned upper limit or less. The lower limit of the thickness of the sealing wall in the line width direction is not particularly limited, but is, for example, 0.5 mm. [Effects of the Invention]

[0081] According to the present invention, it is possible to provide a sealant for an organic EL display element that is excellent in moisture permeation prevention property and adhesiveness, and that can provide an organic EL display element that is excellent in reliability. DETAILED DESCRIPTION OF THE INVENTION

[0082] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0083] ( Reference Examples 1, 7, 8, Example 2~6、 9. Comparative Examples 1 and 2) According to the blending ratios shown in Tables 1 and 2, each material was mixed using a mixer at a stirring speed of 2000 rpm for 3 minutes. Reference Examples 1, 7, 8,Example 2~6、 9, and Comparative Examples 1 and 2 were prepared as sealants for organic EL display elements. The stirring mixer used was AR-250 (manufactured by Thinky Corporation). The calcium oxide used in Tables 1 and 2 was dry batch pulverized in a ball mill (manufactured by Nitto Kagaku Co., Ltd., "ANZ-53D") to a particle size of 10 μm or less.

[0084] <Evaluation> Reference example, Example 、 and 、 The sealants for organic EL display elements obtained in the comparative examples were evaluated as follows, and the results are shown in Tables 1 and 2.

[0085] (1) Viscosity and storage stability Reference example, Example 、 and 、 For each of the sealants for organic EL display elements obtained in the comparative examples, the initial viscosity immediately after production was measured at 25° C. using an E-type viscometer. Furthermore, each sealant for an organic EL display element was frozen for two weeks after production, and then thawed and the viscosity was measured at 25°C, and the viscosity change rate was calculated as (viscosity after two weeks of frozen storage) / (initial viscosity). Storage stability was evaluated by assigning a "◎" when the viscosity change rate was less than 1.1, a "○" when it was 1.1 or more and less than 1.3, a "△" when it was 1.3 or more and less than 1.5, and an "×" when it was 1.5 or more. As the E-type viscometer, a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) was used.

[0086] (2) Adhesiveness Reference example, Example 、 and 、To 10 g of each sealant for organic EL displays obtained in the comparative examples, 0.03 g of spacer particles with a diameter of 10 μm was added and uniformly dispersed using a stirrer mixer. Micropearl SP-210 (manufactured by Sekisui Chemical Co., Ltd.) was used as the spacer particles, and ARV-310 (manufactured by Thinky Corporation) was used as the stirrer mixer. The sealant for organic EL displays with the spacer particles dispersed therein was applied to the center of glass substrate A, and then glass substrate B was attached in a crosswise manner and pressed to make the thickness uniform. The amount of the sealant applied was adjusted so that the sealant for organic EL displays would have a circular shape with a diameter of 5.0 to 7.0 mm after being pressed to make the thickness uniform. The surfaces of glass substrates A and B, each 60 mm long, 30 mm wide, and 5 mm thick, were washed with acetone and then dried. Next, ultraviolet light with a wavelength of 365 nm and 3000 mJ / cm was applied using a UV-LED irradiation device. 2 The sealant for an organic EL display element was cured by irradiation, thereby bonding the glass substrate A and the glass substrate B together to obtain a test piece for evaluating initial adhesion. In addition, the glass substrate A and the glass substrate B were bonded together in the same manner as the test piece for evaluating initial adhesion, and then exposed to high-temperature, high-humidity conditions of 85°C and 85% RH for 500 hours to obtain a test piece for evaluating adhesion after exposure to a high-temperature, high-humidity environment. For each test piece, glass substrate B was placed on the bottom, and both ends of glass substrate A were fixed from below. Both ends of glass substrate B were compressed from above using a precision universal testing machine at 23°C and a speed of 5 mm / min, thereby measuring the adhesive strength between glass substrate A and glass substrate B. The compression points were centered at positions 7.25 mm from both ends of glass substrate B, within an area 20 mm long and 5 mm wide. The precision universal testing machine used was an Autograph AG-Xplus (manufactured by Shimadzu Corporation). The adhesive strength was calculated by dividing the maximum load applied from the start of compression using a precision universal testing machine until glass substrate A and glass substrate B were completely separated by the area of ​​the sealant for organic EL display elements on the test piece. The adhesive strength was 2.0 kgf / cm 2 If it is above 2.0kgf / cm, mark it as "◎" 2 Less than 1.5kgf / cm 2 If it is more than 1.5kgf / cm, mark it as "○" 2Less than 0.8kgf / cm 2 If it is more than 0.8kgf / cm, it is marked as "△" 2 If the adhesion was less than 100%, it was marked "X." The initial adhesion and the adhesion after exposure to a high-temperature, high-humidity environment were evaluated.

[0087] (3) Breathability Reference example, Example 、 and 、 The sealants for organic EL display elements obtained in the comparative examples were subjected to the following Ca-TEST. first, Reference example, Example 、 and 、 To 10 g of each sealant for organic EL display devices obtained in the comparative examples, 0.03 g of spacer particles with a diameter of 10 μm was added and uniformly dispersed using a stirring mixer. Micropearl SP-210 (manufactured by Sekisui Chemical Co., Ltd.) was used as the spacer particles, and ARV-310 (manufactured by Thinky Corporation) was used as the stirring mixer. Next, the sealant for organic EL display devices with the spacer particles dispersed therein was applied to the surface of a glass substrate. Next, a mask with multiple 2mm x 2mm openings was placed on another glass substrate measuring 30mm x 30mm, and Ca was evaporated using a vacuum evaporation system. The evaporation conditions were as follows: the evaporator in the vacuum evaporation system was 2 x 10 -3 The pressure was reduced to 100 Pa, and Ca was deposited at a deposition rate of 5.0 Å / s to form a 2000 Å film. The glass substrate on which Ca was deposited was moved into a glove box controlled at a dew point (above -60°C), and a glass substrate on the surface of which a sealant for organic EL display elements had been applied was bonded to the glass substrate on which Ca was deposited so that the sealant for organic EL display elements was on the Ca deposition pattern. After applying pressure to make the thickness of the sealant layer for organic EL display elements uniform, ultraviolet light with a wavelength of 365 nm was applied at 3000 mJ / cm using a UV-LED irradiation device. 2 The sealant for the organic EL display element was cured by irradiation, and a Ca-TEST substrate was prepared. The obtained Ca-TEST substrate was exposed to high temperature and high humidity conditions of 85°C and 85% RH, and the distance that moisture penetrated from the edge of the glass substrate into the layer consisting of the cured product of the sealant for organic EL display elements was observed from the disappearance of Ca. As a result, when exposed to high temperature and high humidity conditions for 900 hours, moisture penetration resistance was evaluated as follows: if the moisture penetration distance was less than 1.8 mm, it was marked "◎"; if it was 1.8 mm or more but less than 2.1 mm, it was marked "○"; if it was 2.1 mm or more but less than 2.4 mm, it was marked "△"; and if it was 2.4 mm or more, it was marked "×".

[0088] [Table 1]

[0089] [Table 2] [Industrial Applicability]

[0090] According to the present invention, it is possible to provide a sealant for an organic EL display element that is excellent in moisture permeation prevention property and adhesiveness, and that can provide an organic EL display element that is excellent in reliability.

Claims

1. Contains a curable resin and a water-absorbing filler, the curable resin contains a (meth)acrylic compound having no isocyanate group or no blocked isocyanate group, and an isocyanate compound or a blocked isocyanate; the isocyanate compound or the blocked isocyanate has a (meth)acryloyl group, The content of the water-absorbing filler is 20% by weight or more. A sealant for an organic EL display element, characterized in that:

2. 2. The sealant for an organic EL display element according to claim 1, wherein the (meth)acrylic compound having no isocyanate group and no blocked isocyanate group includes a (meth)acrylic compound having an alicyclic skeleton.

3. 3. The sealant for an organic EL display element according to claim 1, wherein the (meth)acrylic compound having no isocyanate group and no blocked isocyanate group includes a polyfunctional (meth)acrylic compound.

4. 4. The sealant for an organic EL display element according to claim 1, wherein the water-absorbing filler contains calcium oxide.

5. 5. The sealant for an organic EL display element according to claim 1, further comprising a polyolefin.

6. 6. The sealant for an organic EL display element according to claim 1, 2, 3, 4 or 5, which has a viscosity of 1000 Pa·s or less as measured at 25° C. and 2.5 rpm using an E-type viscometer.

7. After storing for 500 hours in an environment of 85°C and 85% RH, the adhesive strength of the cured product to glass was 0.8 kgf / cm ２ The sealant for an organic EL display element according to claim 1, 2, 3, 4, 5 or 6, wherein the sealant is a encapsulant for an organic EL display element.

8. 8. The sealant for an organic EL display element according to claim 1, which is used as a peripheral sealant for an organic EL display element for forming a sealing wall around a laminate having an organic light-emitting material layer.

Images