Sealing material for display device, sealing material, organic el display, and LED display

Abstract

This sealing material for a display device contains an epoxy resin, a thermal acid initiator, and a phosphor. The amount of fluorine ions measured by a prescribed test is 100 ppm or less, or the thermal acid initiator is a quaternary ammonium salt in which B(C6F5)4 - is the counteranion.

Description

Sealant for display device, sealant, organic EL display and LED display

[0001] The present invention relates to a sealing material for a display device, a sealing material, an organic EL display, and an LED display.

[0002] In recent years, organic electroluminescence (EL) displays have become known as image display devices equipped with optical elements. In such image display devices, the optical elements are sealed with a sealing layer to prevent deterioration of the optical elements due to moisture in the atmosphere, etc.

[0003] The sealing layer is formed, for example, by embedding the optical element in a sealing material for a display device and then curing the sealing material for a display device.

[0004] As such a display device sealant, for example, a display device sealant containing an epoxy resin and a thermal cationic curing agent has been proposed (see, for example, Patent Document 1).

[0005] International Publication No. 2021 / 024616 Brochure

[0006] On the other hand, image display devices are provided with color filters to display colors on the screen, but from the perspective of miniaturization, it is being considered to incorporate phosphors into sealing materials for display devices instead of color filters.

[0007] However, a cured product of a phosphor-containing sealing material for a display device has a drawback in that it discolors under high temperature and high humidity conditions.

[0008] The present invention provides a sealant for a display device that suppresses discoloration under high temperature and high humidity conditions, a sealant containing a cured product of the sealant for a display device, an organic EL display including the sealant, and an LED display including the sealant.

[0009] The present invention [1] provides an encapsulant for a display device, comprising an epoxy resin, a thermal acid initiator, and a phosphor, and having a fluorine ion content of 100 ppm or less as measured by the following test. <Test> A mixture is prepared by blending components other than the phosphor. A 100 μm-thick layer of the mixture is then applied to a polyethylene terephthalate film and cured to obtain a cured product. The cured product is then peeled from the polyethylene terephthalate film, and placed in a polytetrafluoroethylene heat-resistant container. 5 mL of ultrapure water is then added, and the heat-resistant container is sealed. The heat-resistant container is then placed in a dryer and heated at 100°C for 20 hours to obtain extracted water from the cured product. The heat-resistant container is then cooled to 25°C, and the extracted water is recovered. The extracted water is then diluted, and the fluorine ions in the extracted water are quantified by ion chromatography.

[0010] The present invention [2] includes the display device sealing material according to the above [1], wherein the phosphor is a sulfur-containing phosphor.

[0011] The present invention [3] includes the display device sealing material according to the above [1] or [2], wherein the thermal acid initiator contains a fluorine atom.

[0012] The present invention [4] is a method for preparing a thermal acid initiator, comprising: ６ F ５ ) ４ － The sealing material for a display device according to any one of the above [1] to [3] is a quaternary ammonium salt having a counter anion of

[0013] The present invention [5] includes the encapsulant for a display device according to any one of the above [1] to [4], which further contains an antioxidant.

[0014] The present invention [6] includes the display device encapsulant according to the above [5], wherein the antioxidant includes a hindered phenol antioxidant and a phosphite antioxidant.

[0015] The present invention [7] includes an epoxy resin, a thermal acid initiator, and a phosphor, and the thermal acid initiator is B(C ６ F ５ ) ４－ The sealing material for a display device is a quaternary ammonium salt having the following as a counter anion:

[0016] The present invention [8] includes the display device encapsulant according to the above [7], which further contains an antioxidant.

[0017] The present invention [9] includes the encapsulant for a display device according to any one of [1] to [8] above, which has a color difference of 1.1 or less in the following color difference test. Color difference test: The encapsulant for a display device is applied to a glass plate to form a coating film. The coating film is then heated at 120°C for 60 minutes to cure the coating film, yielding a cured product having a thickness of 100 μm. The cured product is then measured for a* (initial) using a color difference meter. The cured product is then stored at 85°C and 85% humidity for 7 days, and a* (after 7 days) is measured. The color difference is calculated as (|a* (initial)| - |a* (after 7 days)|).

[0018] The present invention

[10] includes an encapsulant containing a cured product of the encapsulant for a display device according to any one of the above [1] to [9].

[0019] The present invention

[11] includes an organic EL display comprising the sealing material according to the above [1].

[0020] The present invention

[12] includes an LED display comprising the encapsulant described in [1] above.

[0021] In the sealing material for a display device of the present invention, the amount of fluorine ions measured by a predetermined test is 100 ppm or less, or the thermal acid initiator is B(C ６ F ５ ) ４ － Therefore, discoloration of the cured product can be suppressed under high temperature and high humidity conditions.

[0022] The encapsulant of the present invention contains a cured product of the encapsulant for a display device of the present invention, and therefore discoloration under high temperature and high humidity conditions can be suppressed.

[0023] The organic EL display of the present invention includes the sealing material of the present invention, and therefore discoloration under high temperature and high humidity conditions can be suppressed.

[0024] The LED display of the present invention includes the sealing material of the present invention, and therefore discoloration under high temperature and high humidity conditions can be suppressed.

[0025] 1. First Invention In the first invention, a display device sealant contains an epoxy resin, a thermal acid initiator, and a phosphor. The sealant contains a fluorine ion content of less than a predetermined value.

[0026] <Epoxy Resin> Examples of the epoxy resin include a siloxane skeleton-free epoxy resin and a siloxane skeleton-containing epoxy resin.

[0027] [Siloxane Skeleton-Free Epoxy Resin] The siloxane skeleton-free epoxy resin does not contain a siloxane skeleton but has an epoxy group.

[0028] Examples of epoxy resins that do not contain a siloxane skeleton include aromatic epoxy resins that do not contain a siloxane skeleton, alicyclic epoxy resins that do not contain a siloxane skeleton, and aliphatic epoxy resins that do not contain a siloxane skeleton.

[0029] (Siloxane Skeleton-Free Aromatic Epoxy Resin) Examples of siloxane skeleton-free aromatic epoxy resins include bisphenol-type epoxy resins (e.g., bisphenol A-type epoxy resins and bisphenol F-type epoxy resins), novolac-type epoxy resins (e.g., phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, and biphenyl novolac-type epoxy resins), and modified products thereof (specifically, alkylene oxide adducts (preferably propylene oxide adducts)).

[0030] The siloxane skeleton-free aromatic epoxy resin is preferably a bisphenol epoxy resin and / or an alkylene oxide adduct of a bisphenol epoxy resin. The siloxane skeleton-free aromatic epoxy resin is more preferably a bisphenol F epoxy resin and / or a propylene oxide adduct of a bisphenol A epoxy resin. The siloxane skeleton-free aromatic epoxy resin is even more preferably a bisphenol F epoxy resin.

[0031] The siloxane skeleton-free aromatic epoxy resin may be a commercially available product, such as YL983U (bisphenol F epoxy resin, manufactured by Mitsubishi Chemical Corporation) or EP-4010S (propylene oxide adduct of bisphenol A epoxy resin, manufactured by ADEKA Corporation).

[0032] (Siloxane Skeleton-Free Alicyclic Epoxy Resin) Examples of siloxane skeleton-free alicyclic epoxy resins include siloxane skeleton-free glycidyl group-containing alicyclic epoxy resins, siloxane skeleton-free glycidyl ether group-containing alicyclic epoxy resins, and siloxane skeleton-free epoxy cyclo structure-containing epoxy resins.

[0033] ((Siloxane Skeleton-Free, Glycidyl Group-Containing Alicyclic Epoxy Resin)) The siloxane skeleton-free, glycidyl group-containing alicyclic epoxy resin has, for example, a glycidyl group bonded to an aliphatic ring. Such a siloxane skeleton-free, glycidyl group-containing alicyclic epoxy resin is, for example, represented by the following general formula (1):

[0034] In formula (1), R represents a monovalent organic group, 1 represents the degree of polymerization, and a substituent such as an alkyl group may be bonded to a carbon atom constituting the cyclohexane ring.

[0035] Specific examples of the siloxane skeleton-free, glycidyl group-containing alicyclic epoxy resin represented by the general formula (1) include 1,2-epoxy-4-(2-oxiranyl)cyclohexane adducts of 2,2-bis(hydroxymethyl)-1-butanol.

[0036] The siloxane skeleton-free, glycidyl group-containing alicyclic epoxy resin represented by the general formula (1) may be a commercially available product, such as EHPE3150 (epoxy equivalent: 170 to 190 g / eq., manufactured by Daicel Corporation).

[0037] ((Siloxane Skeleton-Free, Glycidyl Ether Group-Containing Alicyclic Epoxy Resin)) The siloxane skeleton-free, glycidyl ether group-containing alicyclic epoxy resin has glycidyl ether units bonded to an aliphatic ring. Preferably, the siloxane skeleton-free, glycidyl ether group-containing alicyclic epoxy resin is a siloxane skeleton-free, polyglycidyl ether-containing alicyclic epoxy resin having a plurality of glycidyl ether units bonded to an aliphatic ring.

[0038] Examples of siloxane skeleton-free polyglycidyl ether-containing alicyclic epoxy resins include siloxane skeleton-free bifunctional glycidyl ether-containing alicyclic epoxy resins. Examples of siloxane skeleton-free bifunctional glycidyl ether-containing alicyclic epoxy resins include hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, and hexahydrophthalic acid diglycidyl ester. Preferred siloxane skeleton-free bifunctional glycidyl ether-containing alicyclic epoxy resins include hydrogenated bisphenol A diglycidyl ether.

[0039] The siloxane skeleton-free, glycidyl ether group-containing alicyclic epoxy resin may be a commercially available product. An example of a commercially available siloxane skeleton-free, glycidyl ether group-containing alicyclic epoxy resin is YX8000 (hydrogenated bisphenol A diglycidyl ether, manufactured by Mitsubishi Chemical Corporation).

[0040] ((Siloxane Skeleton-Free Epoxy Cyclo Structure-Containing Epoxy Resin)) The siloxane skeleton-free epoxy cyclo structure-containing epoxy resin has an epoxy cyclo structure having an epoxy group composed of two adjacent carbon atoms forming an aliphatic ring and one oxygen atom bonded to those two carbon atoms.

[0041] Examples of the siloxane skeleton-free epoxy cyclo structure-containing epoxy resin include siloxane skeleton-free epoxy cyclohexane structure-containing epoxy resins (hereinafter referred to as ECH structure-containing epoxy resins).

[0042] Examples of ECH structure-containing epoxy resins include epoxy resins containing one ECH structure represented by the following chemical formula (2), epoxy resins containing one ECH structure represented by the following chemical formula (3), epoxy resins containing two ECH structures represented by the following general formula (4), and modified products thereof.

[0043]

[0044]

[0045]

[0046] In formula (4), X represents a linking group (a divalent group having one or more atoms). R2 represents one atom or substituent selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, an aryl group, a furyl group, and a thienyl group. The two R2 in formula (4) may be the same or different.

[0047] An epoxy resin containing two ECH structures represented by the above general formula (4) (hereinafter referred to as an ECH structure-containing epoxy resin represented by general formula (4)) has ECH structures (epoxycyclohexyl groups) at both ends of the molecule, and the two epoxycyclohexyl groups are bonded via a linking group. The epoxycyclohexyl group is a functional group containing a cyclohexane ring and an epoxy group composed of two adjacent carbon atoms forming the cyclohexane ring and one oxygen atom bonded to those two carbon atoms.

[0048] Examples of the alkyl group represented by R2 in the above general formula (4) include linear or branched alkyl groups having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, pentyl, and hexyl groups).

[0049] Examples of the fluoroalkyl group represented by R2 in the above general formula (4) include linear or branched fluoroalkyl groups having 1 to 6 carbon atoms (e.g., perfluoromethyl, perfluoroethyl, and perfluoropropyl groups).

[0050] Examples of the aryl group represented by R2 in the above general formula (4) include aryl groups having 6 to 18 carbon atoms (such as phenyl and naphthyl groups).

[0051] Examples of the linking group represented by X in the above general formula (4) include an oxygen atom, a sulfur atom, a divalent hydrocarbon group, a polyoxyalkylene group, a carbonyl group, an ether group, a thioether group, an ester group, a carbonate group, an amide group, and groups formed by linking these groups.

[0052] Examples of divalent hydrocarbon groups include linear or branched alkylene groups having 1 to 20 carbon atoms (e.g., methylene, methylmethylene, dimethylmethylene, ethylene, propylene, trimethylene, and butylene), and linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms (e.g., propenylene, methylpropenylene, and butenylene).

[0053] Examples of the polyoxyalkylene group include linear or branched polyoxyalkylene groups having 1 to 120 carbon atoms (such as polyoxyethylene groups and polyoxypropylene groups).

[0054] Specific examples of the ECH structure-containing epoxy resin represented by general formula (4) include (3,3',4,4'-diepoxy)bicyclohexyl, bis(3,4-epoxycyclohexylmethyl)ether, 1,2-bis(3,4-epoxycyclohexane-1-yl)ethane, 2,2-bis(3,4-epoxycyclohexane-1-yl)propane, 3',4'-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate, and ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate. A preferred example of the ECH structure-containing epoxy resin represented by general formula (4) is 3',4'-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate.

[0055] Commercially available ECH structure-containing epoxy resins represented by the general formula (4) can also be used, such as Celloxide 2021P (3',4'-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate) (manufactured by Daicel Corporation).

[0056] As the ECH structure-containing epoxy resin, preferably, an ECH structure-containing epoxy resin represented by the above general formula (4) is used.

[0057] The siloxane skeleton-free alicyclic epoxy resin is preferably a siloxane skeleton-free glycidyl ether group-containing alicyclic epoxy resin and / or a siloxane skeleton-free epoxy cyclo structure-containing epoxy resin.

[0058] (Siloxane Skeleton-Free Aliphatic Epoxy Resin) Examples of siloxane skeleton-free aliphatic epoxy resins include siloxane skeleton-free difunctional aliphatic epoxy resins. Examples of siloxane skeleton-free difunctional aliphatic epoxy resins include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether.

[0059] The siloxane skeleton-free epoxy resin is preferably an aromatic epoxy resin not containing a siloxane skeleton and / or an alicyclic epoxy resin not containing a siloxane skeleton.

[0060] [Siloxane Skeleton-Containing Epoxy Resin] The siloxane skeleton-containing epoxy resin has both a siloxane skeleton and an epoxy group.

[0061] Examples of siloxane skeleton-containing epoxy resins include linear siloxane skeleton-containing epoxy resins, cyclic siloxane skeleton-containing epoxy resins, and ladder-shaped siloxane skeleton-containing epoxy resins.

[0062] (Linear Siloxane Skeleton-Containing Epoxy Resin) The linear siloxane skeleton-containing epoxy resin is, for example, a compound represented by the following formula (5).

[0063] In the above formula (5), m represents an integer of 1 or more and 20 or less. Also, in the above formula (5), n represents an integer of 1 or more and 10 or less. Also, in the above formula (5), o represents an integer of 1 or more and 10 or less. In the above formula (5), Y represents an epoxy group or an epoxycyclo group (for example, an epoxycyclohexane group). Note that in the above formula (5), the two Ys are the same or different from each other.

[0064] The linear siloxane skeleton-containing epoxy resin is preferably a compound represented by the following formula (6) (a compound in which, in the above formula (5), m represents 1, n represents 2, o represents 2, and two Ys represent epoxycyclohexane groups):

[0065] Alternatively, commercially available linear siloxane skeleton-containing epoxy resins may be used, such as X-40-2669 (a compound represented by the above formula (6), manufactured by Shin-Etsu Chemical Co., Ltd.).

[0066] (Epoxy Resin Having a Cyclic Siloxane Skeleton) The epoxy resin having a cyclic siloxane skeleton has a cyclic siloxane skeleton.

[0067] Examples of the cyclic siloxane skeleton include a hexamethylcyclotrisiloxane skeleton (C ６ H １８ O ３ Si ３ ), octamethylcyclotetrasiloxane skeleton (C ８ H ２４ O ４ Si ４ ), and decamethylcyclopentasiloxane skeleton (C １０ H ３０ O ５ Si ５ ) are listed.

[0068] The cyclic siloxane skeleton-containing epoxy resin preferably has an octamethylcyclotetrasiloxane skeleton.

[0069] Such a cyclic siloxane skeleton-containing epoxy resin is, for example, a compound represented by the following formula (7).

[0070] In the above formula (7), Z represents a linking group (a divalent group having one or more atoms). Examples of the linking group include alkylene groups having 1 to 8 carbon atoms. Examples of alkylene groups having 1 to 8 carbon atoms include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, and octylene groups.

[0071] In addition, in the above formula (7), Y has the same meaning as Y in the above formula (5).

[0072] In addition, in the above formula (7), R ３ represents a saturated hydrocarbon group or -Z-Y. Examples of saturated hydrocarbon groups include linear or branched alkyl groups having 1 to 6 carbon atoms and cycloalkyl groups having 3 to 6 carbon atoms. Examples of linear or branched alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, and hexyl groups. Examples of cycloalkyl groups having 3 to 6 carbon atoms include cyclopentyl and cyclohexyl groups. In the above formula (7), the six R ３ are the same or different from each other.

[0073] The cyclic siloxane skeleton-containing epoxy resin preferably includes a compound represented by the following formula (8) and / or a compound represented by the following formula (9).

[0074] Alternatively, commercially available cyclic siloxane skeleton-containing epoxy resins may be used, such as X-40-2678 (a compound represented by the above formula (8), manufactured by Shin-Etsu Chemical Co., Ltd.) and KR-470 (a compound represented by the above formula (9), manufactured by Shin-Etsu Chemical Co., Ltd.).

[0075] (Ladder-like siloxane skeleton-containing epoxy resin) The ladder-like siloxane skeleton-containing epoxy resin contains a ladder-like siloxane skeleton.

[0076] The ladder-like siloxane skeleton is a two-dimensional network structure in which siloxane bonds have a ladder-like skeleton, as shown in the following formula (10).

[0077] An example of the ladder-like siloxane skeleton-containing epoxy resin is a compound represented by the following formula (11).

[0078] Alternatively, the ladder-shaped siloxane skeleton-containing epoxy resin may be a commercially available product, such as YL-9028 (a compound represented by the above formula (10), manufactured by Mitsubishi Chemical Corporation).

[0079] The weight average molecular weight of the epoxy resin is, for example, 130 or more and, for example, 3000 or less. The weight average molecular weight (Mw) can be determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0080] The epoxy equivalent of the epoxy resin is, for example, 100 g / eq. or more, and for example, 1000 g / eq. or less. The epoxy equivalent can be measured in accordance with JIS K7236:2001.

[0081] The epoxy resins can be used alone or in combination of two or more kinds.

[0082] The content of the epoxy resin in the display device sealing material is, for example, 20 mass % or more, or preferably 30 mass % or more, and for example, 60 mass % or less.

[0083] <Thermal Acid Initiator> The thermal acid initiator is a thermal acid generator that generates an acid by heat.

[0084] The thermal acid initiator contains fluorine atoms and is selected so that the amount of fluorine ions, which will be described later, is equal to or less than a predetermined value.

[0085] Examples of such thermal acid initiators include B(C ６ F ５ ) ４ － Examples of the counter anion include quaternary ammonium salts.

[0086] In addition, commercially available thermal acid initiators can also be used. Examples of commercially available thermal acid initiators include CXC-1821(B(C ６ F ５ ) ４ － as a counter anion, manufactured by King Industries).

[0087] The thermal acid initiators can be used alone or in combination of two or more.

[0088] The content ratio of the thermal acid initiator relative to 100 parts by mass of the epoxy resin is, for example, 1 part by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass or less.

[0089] The content of the thermal acid initiator relative to the sealing material for a display device is, for example, 0.5 mass % or more and, for example, 5 mass % or less, preferably 2.5 mass % or less.

[0090] <Phosphor> Phosphors have a wavelength conversion function, for example, converting light from an optical element into light of a predetermined wavelength.

[0091] Phosphors include sulfur-containing and sulfur-free phosphors.

[0092] Examples of sulfur-containing phosphors include sulfur-containing red phosphors, sulfur-containing green phosphors, sulfur-containing blue phosphors, and sulfur-containing yellow phosphors.

[0093] Examples of sulfur-containing red phosphors include (Ca, Sr)S:Eu, (Zn, Cd)(S, Se):Ag, Ba２ ZnS ３ : Mn, (Ca １－ｘ Sr ｘ ) S: Eu, In (0<x<1), and La ２ O ２ S: Eu can be mentioned.

[0094] Examples of sulfur-containing green phosphors include (Ca, Sr, Ba) (Al, Ga, In) ２ S ４ Examples of suitable alloys include SrS:Eu, SrS:Tb, and CaS:Ce.

[0095] Examples of sulfur-containing blue phosphors include SrS:Ce, (Sr, Ca)Ga ２ S ４ : Ce, BaAl ２ S ４ : Eu, Ba ２ SiS ４ : Ce, Ba ２ (Si １－ｘ Al ｘ ) S ４ :Ce(0<x<1)

[0096] Examples of sulfur-containing yellow phosphors include CaGa ２ S ４ : Eu, Sr ２ SiS ４ :Eu and CaS:Ce,Eu.

[0097] Sulfur-free phosphors include sulfur-free yellow phosphors and sulfur-free red phosphors.

[0098] Examples of sulfur-free yellow phosphors include Y ３ Al ５ O １２ : Ce and Tb ３ Al ３ O １２ : Ce is mentioned.

[0099] Examples of sulfur-free red phosphors include CaAlSiN ３ : Eu and CaSiN ２ : Eu can be mentioned.

[0100] As the phosphor, preferably, a sulfur-containing phosphor is used from the viewpoint of increasing color purity, and more preferably, a sulfur-containing green phosphor is used.

[0101] The phosphors can be used alone or in combination of two or more kinds.

[0102] The content ratio of the phosphor relative to the components other than the phosphor (specifically, the epoxy resin, the thermal acid initiator, and other components that are blended as necessary (described later)) is, for example, 60 parts by mass or more, preferably 80 parts by mass or more, and for example, 150 parts by mass or less, preferably 120 parts by mass or less.

[0103] The content of the phosphor is, for example, 40 parts by mass or more, preferably 80 parts by mass or more, and for example, 250 parts by mass or less, preferably 180 parts by mass or less, more preferably 130 parts by mass or less, per 100 parts by mass of the epoxy resin.

[0104] The content of the phosphor in the sealing material for a display device is, for example, 40 mass % or more and, for example, 60 mass % or less.

[0105] <Other Components> The display device encapsulant may contain other components as needed.

[0106] The other components include, for example, other cationic polymerizable compounds and additives.

[0107] [Other Cationic Polymerizable Compounds] The other cationic polymerizable compounds are cationic polymerizable compounds other than epoxy resins, and examples thereof include oxetane compounds.

[0108] The oxetane compound contains, for example, 1 to 5 oxetane rings.

[0109] Examples of the oxetane compound include monofunctional oxetane compounds having one oxetane ring, bifunctional oxetane compounds having two oxetane rings, and trifunctional or higher oxetane compounds having three or more oxetane rings.

[0110] Examples of monofunctional oxetane compounds include 2-ethylhexyl oxetane, 3-ethyl-3-hydroxymethyl oxetane, 3-(meth)allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy)methylbenzene, 2-ethylhexyl (3-ethyl-3-oxetanylmethyl) ether, ethyl diethylene glycol (3-ethyl-3-oxetanylmethyl) ether, and 3-cyclohexylmethyl-3-ethyl-oxetane.

[0111] Examples of bifunctional oxetane compounds include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxy]benzene, 1,3-bis[(3-ethyl-3-oxetanyl)methoxy]benzene, 3,7-bis(3-oxetanyl)-5-oxa-nona Examples of the difunctional oxetane compound include 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, and dicyclopentenyl bis(3-ethyl-3-oxetanylmethyl)ether. Examples of the difunctional oxetane compound include 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane.

[0112] Commercially available bifunctional oxetane compounds can also be used, such as Aronoxetane OXT-221 (3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, manufactured by Toagosei Chemical Industry Co., Ltd.).

[0113] Examples of tri- or higher functional oxetane compounds include trimethylolpropane tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis(3-ethyl-3-oxetanylmethyl) ether, and dipentaerythritol pentakis(3-ethyl-3-oxetanylmethyl) ether.

[0114] As the oxetane compound, preferably, a bifunctional oxetane compound is used.

[0115] The other cationic polymerizable compounds can be used alone or in combination of two or more kinds.

[0116] The content ratio of the other cationic polymerizable compounds relative to 100 parts by mass of the epoxy resin is, for example, 60 parts by mass or more, preferably 80 parts by mass or more, and for example, 150 parts by mass or less, preferably 120 parts by mass or less.

[0117] The content of the other cationic polymerizable compounds is, for example, 10% by mass or more and, for example, 30% by mass or less, relative to the mass of the display device sealing material.

[0118] [Additives] Examples of additives include tackifiers, photosensitizers, leveling agents, coupling agents, light stabilizers, antioxidants, polymerization initiator aids, antiaging agents, wettability improvers, surfactants, plasticizers, UV absorbers, preservatives, and antibacterial agents. Preferably, additives include light stabilizers and / or antioxidants, from the viewpoint of further suppressing discoloration of the cured product under high temperature and high humidity conditions. The additives can be used alone or in combination of two or more.

[0119] Examples of the light stabilizer include hindered amine light stabilizers, such as tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate. The light stabilizer preferably includes bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate.

[0120] Commercially available light stabilizers can also be used, such as Adekastab LA-81 (bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate, manufactured by ADEKA Corporation).

[0121] The light stabilizers can be used alone or in combination of two or more kinds.

[0122] The content ratio of the light stabilizer relative to 100 parts by mass of the epoxy resin is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and for example, 5 parts by mass or less, preferably 2 parts by mass or less.

[0123] The content of the light stabilizer in the display device sealing material is, for example, 0.05 mass % or more, preferably 0.25 mass % or more, and for example, 2.5 mass % or less, preferably 1 mass % or less.

[0124] Antioxidants include, for example, hindered phenol antioxidants and phosphite antioxidants.

[0125] Examples of hindered phenol antioxidants include 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,1,3-tris-(2'-methyl-4'-hydroxy-5'-t-butylphenyl)-butane, 3-(3,5-di-t-butyl-4-hydroxyphenyl)stearyl propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 3,9-bis[2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. A preferred example of the hindered phenol antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0126] Examples of the phosphite antioxidant include tris(2-ethylhexyl)phosphite, isodecyldiphenylphosphite, trilaurylphosphite, tris(tridecyl)phosphite, and tri(stearyl)phosphite. Preferred examples of the phosphite antioxidant include isodecyldiphenylphosphite.

[0127] The content ratio of the antioxidant relative to 100 parts by mass of the epoxy resin is, for example, 1 part by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass or less.

[0128] The content of the antioxidant relative to the sealing material for a display device is, for example, 0.5 mass % or more and, for example, 5 mass % or less, preferably 2.5 mass % or less.

[0129] The antioxidants can be used alone or in combination of two or more. Preferably, a hindered phenol antioxidant and a phosphite antioxidant are used in combination, from the viewpoint of further suppressing discoloration of the cured product under high temperature and high humidity conditions.

[0130] When a hindered phenol antioxidant and a phosphite antioxidant are used in combination as antioxidants, the content of the hindered phenol antioxidant is, per 100 parts by mass of the total amount of the hindered phenol antioxidant and the phosphite antioxidant, for example, 30 parts by mass or more, preferably 40 parts by mass or more, and for example, 70 parts by mass or less, preferably 60 parts by mass or less. The content of the phosphite antioxidant is, per 100 parts by mass of the total amount of the hindered phenol antioxidant and the phosphite antioxidant, for example, 30 parts by mass or more, preferably 40 parts by mass or more, and for example, 70 parts by mass or less, preferably 60 parts by mass or less.

[0131] <Preparation of Sealant for Display Device> To prepare the sealant for a display device, an epoxy resin, a thermal acid initiator, a phosphor, and other components that are blended as required are mixed together.

[0132] Specifically, first, an epoxy resin, a thermal acid initiator, and other components that are added as needed are mixed together to prepare a mixture.

[0133] Next, this mixture is mixed with a phosphor to prepare an encapsulant for a display device.

[0134] The sealant for a display device can also be diluted with a known solvent to form a varnish. In such a case, the solid content concentration of the varnish of the sealant for a display device is, for example, 10 mass % or more and, for example, 70 mass % or less.

[0135] The display device sealing material has a fluorine ion content of 100 ppm or less, preferably 50 ppm or less, more preferably 20 ppm or less, and usually 1 ppm or more, as measured by the test described below.

[0136] Specifically, in the test, a mixture was prepared by blending components other than the phosphor. Then, a 100 μm thick mixture was applied to a polyethylene terephthalate film using an applicator and cured to obtain a cured product. The cured product was then peeled off from the polyethylene terephthalate film, and placed in a polytetrafluoroethylene heat-resistant container. 5 mL of ultrapure water was added, and the heat-resistant container was sealed. The heat-resistant container was then placed in a dryer and heated at 100°C for 20 hours to obtain the extracted water from the cured product. The heat-resistant container was then cooled to 25°C, and the extracted water was recovered. The extracted water was then diluted, and the fluorine ions in the extracted water were quantified using ion chromatography.

[0137] When the amount of fluorine ions is equal to or less than the upper limit, discoloration of the cured product can be suppressed under high temperature and high humidity conditions.

[0138] If the amount of fluorine ions exceeds the upper limit, discoloration of the cured product under high temperature and high humidity conditions cannot be suppressed.

[0139] Furthermore, in the sealing material for display devices, the color difference measured by the color difference test described below is, for example, 5.0 or less, preferably 4.0 or less, more preferably 3.0 or less, even more preferably 2.0 or less, and from the viewpoint of further suppressing discoloration of the cured product, particularly preferably 1.1 or less.

[0140] Such a sealant for a display device can suppress discoloration of the cured product under high temperature and high humidity conditions, and can therefore be suitably used as a sealant for sealing optical elements.

[0141] <Sealant> The sealant includes a cured product of the sealant for a display device described above.

[0142] In order to harden the display device sealant, the display device sealant is heated.

[0143] Regarding the heating conditions, the heating temperature is, for example, 60° C. or more, preferably 100° C. or more, and for example, 150° C. or less. The heating time is, for example, 1 minute or more, preferably 30 minutes or more, and for example, 120 minutes or less.

[0144] As a result, the display device sealant is cured to obtain a cured product of the display device sealant.

[0145] The cured product of the encapsulant for a display device preferably has transparency. Specifically, the total light transmittance (based on JIS K 7361-1) of the cured product of the encapsulant for a display device is, for example, 80% or more, preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more, and for example, 100% or less.

[0146] Such a sealing material can be suitably used in the manufacture of organic EL displays and LED displays.

[0147] That is, an organic EL display includes an organic EL element and a sealing material. More specifically, an organic EL display includes an organic EL element and a sealing material that covers the surface of the organic EL element. Also, an LED display includes an LED and a sealing material. More specifically, an LED display includes an LED and a sealing material that covers the surface of the LED.

[0148] 2. Second Invention In the second invention, the display device sealing material contains an epoxy resin, a thermal acid initiator, and a phosphor. The thermal acid initiator is B(C ６ F ５ ) ４ － is a quaternary ammonium salt with the counter anion

[0149] The display device encapsulant is B (C ６ F ５ ) ４ － The thermal acid initiator is a quaternary ammonium salt having a counter anion of , and therefore discoloration of the cured product can be suppressed under high temperature and high humidity conditions. The content of the thermal acid initiator is the same as that of the thermal acid initiator of the first invention.

[0150] The epoxy resin and the phosphor are the same as those exemplified in the first invention, and the content ratios thereof are the same as those exemplified in the first invention.

[0151] The display device encapsulant may further contain other components as exemplified in the first invention, if necessary, in the same proportions as those exemplified in the first invention.

[0152] The display device encapsulant can be prepared by the same method as in the first invention. Furthermore, by curing the display device encapsulant by the same method as in the first invention, a cured product (encapsulant) of the display device encapsulant similar to that of the first invention can be produced. Furthermore, this encapsulant can be used to produce organic EL displays and LED displays similar to those of the first invention.

[0153] 3. Effects In the display device sealing material, the amount of fluorine ions measured by a predetermined test is 100 ppm or less, or in the display device sealing material, the thermal acid initiator is B(C ６ F ５ ) ４ － Therefore, discoloration of the cured product can be suppressed under high temperature and high humidity conditions.

[0154] Specifically, a cured product of a phosphor-containing sealing material for a display device has a problem of discoloration due to fluorine ions generated from a thermal acid initiator under high temperature and high humidity conditions.

[0155] In particular, epoxy resins are selected over silicone resins from the viewpoint of improving heat resistance, water resistance, and adhesiveness, but when epoxy resins are selected, the above-mentioned discoloration is more likely to occur.

[0156] On the other hand, in the display device sealing material, the amount of fluorine ions measured by a predetermined test is 100 ppm or less, or in the display device sealing material, the thermal acid initiator is B(C ６ F ５ ) ４ － Since it is a quaternary ammonium salt with a counter anion of , the amount of fluorine ions generated from the thermal acid initiator is suppressed, and therefore, even if an epoxy resin is included, discoloration of the cured product can be suppressed under high temperature and high humidity conditions.

[0157] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are by mass unless otherwise specified. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be substituted with the corresponding upper limit values ​​(numeric values ​​defined as "equal to or less than") or lower limit values ​​(numeric values ​​defined as "equal to or more than" or "exceeding") of the blending ratios (content ratios), physical property values, parameters, etc. described in the above "Modes for Carrying Out the Invention."

[0158] <Details of Components> The trade names and abbreviations of the components used in each example and each comparative example are described in detail below. YL983U: bisphenol F type epoxy resin, manufactured by Mitsubishi Chemical Corporation EP-4010S: propylene oxide adduct of bisphenol A type epoxy resin, manufactured by ADEKA Corporation YX8000: hydrogenated bisphenol A diglycidyl ether, manufactured by Mitsubishi Chemical Corporation CEL2021P: 3',4'-epoxycyclohexylmethyl (3,4-epoxy) cyclohexane carboxylate, an ECH structure-containing epoxy resin represented by the above general formula (4), trade name "Celloxide 2021P", epoxy equivalent: 128 to 145 g / eq. , Daicel Corporation X-40-2669: linear siloxane skeleton-containing epoxy resin (compound represented by the above formula (6)), Shin-Etsu Chemical Co., Ltd. X-40-2678: cyclic siloxane skeleton-containing epoxy resin (compound represented by the above formula (8)), Shin-Etsu Chemical Co., Ltd. KR-470: cyclic siloxane skeleton-containing epoxy resin (compound represented by the above formula (9)), Shin-Etsu Chemical Co., Ltd. YL-9028: ladder-type siloxane skeleton-containing epoxy resin (compound represented by the above formula (10)), Mitsubishi Chemical Corporation CXC-1821: B(C ６ F ５ ) ４ － as a counter anion, King Industries CXC-1733: SbF ６ －as a counter anion, OXT-221: 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, trade name "Aron Oxetane OXT-221" manufactured by King Industries, LA-81: bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate, trade name "ADEKA STAB LA-81" manufactured by Toa Gosei Chemical Co., Ltd., AO-60: hindered phenol antioxidant (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] manufactured by ADEKA, 135A: phosphite antioxidant (isodecyl diphenyl phosphite) manufactured by ADEKA.

[0159] <Preparation of encapsulants for display devices> Examples 1 to 13 and Comparative Examples 1 to 5 Epoxy resins, thermal acid initiators, and other components were mixed with a magnetic stirrer based on the formulations shown in Tables 1 and 2. This prepared mixtures.

[0160] Next, this mixture and a phosphor (sulfur-containing phosphor) were blended at a mass ratio of 1 / 1 (mixture / phosphor), and mixed at 1,600 rpm for 1 minute using a V-Mini 300 manufactured by EME. Thus, an encapsulant for a display device was prepared. The numerical values ​​of each component listed in Tables 1 and 2 are in parts by mass.

[0161] <Evaluation> [Quantity of Fluoride Ions] A mixture consisting of components other than the phosphor was prepared based on the formulation of each Example and Comparative Example. Next, a 100 μm-thick layer of the mixture (a mixture consisting of components other than the phosphor) was applied to a polyethylene terephthalate film using an applicator and cured to obtain a cured product. The cured product was then peeled from the polyethylene terephthalate film, and placed in a polytetrafluoroethylene heat-resistant container. 5 mL of ultrapure water was added, and the heat-resistant container was sealed. The heat-resistant container was then placed in a dryer and heated at 100°C for 20 hours to obtain an extract from the cured product. The heat-resistant container was then cooled to 25°C, and the extract was recovered. The extract was then diluted, and the fluoride ions in the extract were quantified using ion chromatography (measuring device: ICS-3000 (manufactured by Thermo Fisher Scientific)). The results are shown in Tables 1 and 2.

[0162] [Color Difference Test] Each of the display device sealing materials of Examples and Comparative Examples was applied to a glass plate to form a coating film. The coating film was then heated at 120°C for 60 minutes to cure, thereby obtaining a cured product (thickness: 100 µm).

[0163] Next, the cured product was measured using a color difference meter (SE2000, manufactured by Nippon Denshoku Industries Co., Ltd.) ＊ The cured product was then stored at 85°C and 85% humidity for 2 days. ＊ The cured product was then stored at 85°C and 85% humidity for an additional 5 days. ＊ (After 7 days) was measured. ＊ (initial) |-|a ＊ The smaller the value of (after 7 days)|), the more the discoloration can be suppressed under high temperature and high humidity. The results are shown in Tables 1 and 2.

[0164] <Discussion> Examples 1 to 13, in which the amount of fluorine ions is 100 ppm or less, have smaller color differences than Comparative Examples 1 to 5, in which the amount of fluorine ions exceeds 100 ppm. This shows that if the amount of fluorine ions is 100 ppm or less, discoloration can be suppressed under high temperature and high humidity conditions.

[0165]

[0166]

[0167] The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0168] The encapsulant for a display device and the encapsulant of the present invention are suitably used for, for example, an organic EL display and an LED display. The organic EL display and the LED display of the present invention are suitably used in the manufacture of a display device.

Claims

1. comprising an epoxy resin, a thermal acid initiator, and a phosphor; A sealing material for a display device, in which the amount of fluorine ions measured by the following test is 100 ppm or less. <Test> The components other than the phosphor are blended to prepare a mixture, which is then applied to a polyethylene terephthalate film to a thickness of 100 μm and cured to obtain a cured product. Next, the cured product is peeled off from the polyethylene terephthalate film, and the cured product is placed in a polytetrafluoroethylene heat-resistant container, and 5 mL of ultrapure water is added, and the heat-resistant container is sealed. Next, the heat-resistant container is placed in a dryer and heated at 100°C for 20 hours to obtain the extracted water extracted from the cured product. Next, the heat-resistant container is cooled to 25°C, and the extracted water is collected. Next, the extracted water is diluted, and the fluorine ions in the extracted water are quantified by ion chromatography.

2. The display device encapsulant according to claim 1 , wherein the phosphor is a sulfur-containing phosphor.

3. The display device encapsulant according to claim 1 , wherein the thermal acid initiator contains a fluorine atom.

4. The thermal acid initiator is B(C ６ F ５ ) ４ － The sealing material for a display device according to claim 1 , which is a quaternary ammonium salt having a counter anion of

5. The encapsulant for a display device according to claim 1 , further comprising an antioxidant.

6. The encapsulant for a display device according to claim 5 , wherein the antioxidant comprises a hindered phenol antioxidant and a phosphite antioxidant.

7. comprising an epoxy resin, a thermal acid initiator, and a phosphor; The thermal acid initiator is B(C ６ F ５ ) ４ － The sealing material for display devices is a quaternary ammonium salt having a counter anion of

8. The encapsulant for a display device according to claim 7 , further comprising an antioxidant.

9. The encapsulant for a display device according to claim 1 , which has a color difference of 1.1 or less in the following color difference test. Color difference test: The display sealant is applied to a glass plate to form a coating film. The coating film is then heated at 120°C for 60 minutes to cure the coating film, and a cured product having a thickness of 100 μm is obtained. A color difference meter is then used to measure a* (initial) for the cured product. The cured product is then stored at 85°C and 85% humidity for 7 days, and a* (after 7 days) is measured. (|a* (initial)|-|a* (after 7 days)|) is defined as the color difference.

10. An encapsulant comprising a cured product of the encapsulant for a display device according to claim 1 .

11. An organic electroluminescence display comprising the sealing material according to claim 10.

12. An LED display comprising the encapsulant of claim 10.

Images