Resin composition for display elements

Abstract

The present invention provides a resin composition for display elements that exhibits excellent coatability and whose cured product has excellent low dielectric properties and heat resistance. [Solution] A resin composition for a display element containing a curable resin and a photocationic polymerization initiator, wherein the curable resin comprises at least one selected from the group consisting of a cationic polymerizable compound having a vinyl group, a cationic polymerizable compound having an isopropenyl group, and a cationic polymerizable compound having a vinyl ether group, and the resin composition for the display element further comprises at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer, wherein the content of at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer in a total of 100 parts by mass of the curable resin and at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer is 5.1 parts by mass or more and 15.0 parts by mass or less.

Description

[Technical Field]

[0001] This invention relates to a resin composition for display elements. [Background technology]

[0002] Touch panels are used in electronic devices such as mobile phones, smartphones, car navigation systems, and personal computers, and among them, capacitive touch panels are rapidly gaining popularity due to their superior functionality. In particular, in recent years, development of display elements such as organic EL display elements equipped with capacitive touch panels has progressed. For resin compositions for display elements used in sealing display elements equipped with touch panels, there is a need for materials that have appropriate viscosity, excellent coatability, and excellent curability. Furthermore, with the recent trend towards thinner and larger capacitive touch panels, in order to prevent a decrease in the response speed of the touch panel, resin compositions for display elements are also required to have low dielectric properties such as low dielectric constant and low dielectric loss tangent. As a resin composition for display elements with excellent photocurability and low dielectric properties, for example, Patent Document 1 discloses a composition containing a vinyl monomer such as divinylbenzene and a photoacid generator (photocationic polymerization initiator). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-190428 [Overview of the project] [Problems that the invention aims to solve]

[0004] Resin compositions using vinyl monomers, such as those disclosed in Patent Document 1, are expected to be used as encapsulants for display elements, particularly those requiring low dielectric properties. However, resin compositions using vinyl monomers have problems such as poor coatability, and when polymers with low dielectric constants are added to further improve low dielectric properties, they may have poor heat resistance.

[0005] The present invention aims to provide a resin composition for display elements that exhibits excellent coatability and whose cured product has excellent low dielectric properties and heat resistance. [Means for solving the problem]

[0006] Disclosure 1 is a resin composition for a display element containing a curable resin and a photocationic polymerization initiator, wherein the curable resin comprises at least one selected from the group consisting of a cationic polymerizable compound having a vinyl group, a cationic polymerizable compound having an isopropenyl group, and a cationic polymerizable compound having a vinyl ether group, and the resin composition for the display element further contains at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer, and the content of at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer in a total of 100 parts by mass of the curable resin and at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer is 5.1 parts by mass or more and 15.0 parts by mass or less. Disclosure 2 is a resin composition for display elements of Disclosure 1, wherein the dielectric constant of the cured product measured under conditions of 25°C and 100kHz is 2.60 or less. The present invention will be described in detail below.

[0007] The present inventors investigated a resin composition for display elements containing a cationic polymerizable compound having a specific structure and a photocationic polymerization initiator, further incorporating a specific amount of at least one polymer selected from the group consisting of hydrogenated petroleum resins and cycloolefin polymers. As a result, they found that a resin composition for display elements with excellent coatability and cured products with excellent low dielectric properties and heat resistance could be obtained, thus completing the present invention.

[0008] The resin composition for display elements of the present invention contains a curable resin. The above-mentioned curable resin includes at least one selected from the group consisting of a cationic polymerizable compound having a vinyl group, a cationic polymerizable compound having an isopropenyl group, and a cationic polymerizable compound having a vinyl ether group (hereinafter also referred to as "the cationic polymerizable compound according to the present invention"). By using the cationic polymerizable compound according to the present invention in combination with at least one polymer selected from the group consisting of hydrogenated petroleum resins and cycloolefin polymers (hereinafter also referred to as "the low dielectric polymer according to the present invention"), and further setting the content of the low dielectric polymer according to the present invention within the range described later, the resin composition for display elements of the present invention exhibits excellent coatability, and the cured product has excellent low dielectric properties and heat resistance. In this specification, the cationic polymerizable compounds having a vinyl group described above do not include cationic polymerizable compounds having a vinyl ether group described above.

[0009] Examples of cationic polymerizable compounds having the vinyl group mentioned above include 1,2-divinylbenzene, 1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-divinyl-5-methylbenzene, 1,3-divinyl-2-methylbenzene, 1,3-divinylcyclobutadiene, m-methylstyrene, m-ethylstyrene, m-propylstyrene, 1-allyl-3-vinylbenzene, 3,5-dimethylstyrene, 1-vinyl-3-propylbenzene, 1-vinyl-3-ethynylbenzene, 1,3,5-trivinylbenzene, and 1,2-divinyl-3-methylbenzene. Among these, 1,3-divinylbenzene and 1,4-divinylbenzene are preferred.

[0010] Examples of cationic polymerizable compounds having the isopropenyl group include 1,2-diisopropenylbenzene, 1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, 1-vinyl-3-propenylbenzene, 1-isopropyl-3-propenylbenzene, 1,3-diisopropenyl-5-ethylbenzene, 1-isopropenyl-3-isobutylbenzene, 1-isopropenyl-3-methylbenzene, 1-isopropenyl-3-ethylbenzene, and 1,3,5-triisopropenylbenzene. Among these, 1,3-diisopropenylbenzene and 1,4-diisopropenylbenzene are preferred.

[0011] Examples of cationic polymerizable compounds having the vinyl ether group mentioned above include dicyclopentadiene monovinyl ether, benzyl vinyl ether, cyclohexanedimethanol monovinyl ether, 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, phenyl vinyl ether, cycloheptyl vinyl ether, cyclopentyl vinyl ether, cyclobutyl vinyl ether, cyclooctyl vinyl ether, 3-methyl-1-cyclohexyl vinyl ether, 2-methyl-1-cyclohexyl vinyl ether, 4-methyl-1-cyclohexyl vinyl ether, 2-methylene-1-cyclohexyl vinyl ether, cyclobutadiene vinyl ether, 4-methyl-1-phenyl vinyl ether, and 2-methyl-1-phenyl vinyl ether. Among these, dicyclopentadiene monovinyl ether, cyclohexanedimethanol monovinyl ether, and cyclohexanedimethanol divinyl ether are preferred.

[0012] The preferred lower limit for the content of the cationic polymerizable compound according to the present invention in a total of 100 parts by mass of the above-mentioned curable resin and the low dielectric polymer according to the present invention is 85 parts by mass, and the preferred upper limit is 94.9 parts by mass. When the content of the cationic polymerizable compound according to the present invention is 85 parts by mass or more, the resin composition for display elements of the present invention has superior curability, and the cured product has superior low dielectric properties and heat resistance. When the content of the cationic polymerizable compound according to the present invention is 94.9 parts by mass or less, the resin composition for display elements of the present invention has superior coatability, and the cured product has superior discoloration prevention properties. The more preferred lower limit for the content of the cationic polymerizable compound according to the present invention is 88 parts by mass, and the more preferred upper limit is 91.9 parts by mass.

[0013] The above-mentioned curable resin may include other curable resins other than the cationic polymerizable compound according to the present invention, as long as they do not hinder the objectives of the present invention. Examples of other curable resins mentioned above include epoxy compounds, oxetane compounds, (meth)acrylic compounds, and the like.

[0014] Examples of the epoxy compounds mentioned above include alicyclic epoxy-modified silicone compounds, 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol E type epoxy compounds, phenylglycidyl ether, phenylenediglycidyl ether, 4,4'-bis(1,2-epoxycyclohexane), bis(3,4-epoxycyclohexylmethyl) ether, bis(3,4-epoxycyclohexane-1-ylmethyl) adipate, and 1,2-epoxy-4-(2-oxymethyl) 2,2-bis(hydroxymethyl)-1-butanol. Examples include lanyl cyclohexane adducts, fluorene-type epoxy compounds, 1,7-octadiene diepoxides, neopentyl glycol diglycidyl ethers, ethylene glycol diglycidyl ethers, diethylene glycol diglycidyl ethers, polyethylene glycol diglycidyl ethers, propylene glycol diglycidyl ethers, dipropylene glycol diglycidyl ethers, tripropylene glycol diglycidyl ethers, polypropylene glycol diglycidyl ethers, 1,6-hexanediol diglycidyl ethers, glycerin diglycidyl ethers, trimethylolpropane triglycidyl ethers, and the like.

[0015] Examples of the above oxetane compounds include 3-ethyl-3-((2-ethylhexyloxy)methyl)oxetane, 3-ethyl-3-(((3-ethyloxetan-3-yl)methoxy)methyl)oxetane, 3-ethyl-3-((3-(triethoxysilyl)propoxy)methyl)oxetane, phenol novolac oxetane, and 1,4-bis(((3-ethyl-3-oxetanyl)methoxy)methyl)benzene.

[0016] Examples of the above (meth)acrylic compound include 1,6 - hexanediol di(meth)acrylate, 1,9 - nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, 1,12 - dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, (meth)acrylic - modified organosiloxane, and the like. In the present specification, the above "(meth)acrylate" means acrylate or methacrylate.

[0017] The resin composition for a display element of the present invention contains a photo - cationic polymerization initiator. The above photo - cationic polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid upon light irradiation, and it may be an ionic photo - acid - generating type or a non - ionic photo - acid - generating type.

[0018] Examples of the anion part of the above ionic photo - acid - generating type photo - cationic polymerization initiator include BF4 - , PF6 - , SbF6 - , (BX4) - (where X represents a phenyl group substituted with at least two or more fluorine or trifluoromethyl groups), and the like. Also, examples of the above anion part include PF m (C n F 2n+1 ) 6-m - (where m is an integer of 0 or more and 5 or less, and n is an integer of 1 or more and 6 or less), and the like. Examples of the ionic photoacid-generating photo cationic polymerization initiator include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salts, etc., which have the above-mentioned anion moiety.

[0019] Examples of the aromatic sulfonium salts 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 hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, 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, tris(4-(4-acetylphenyl)thiophenyl)sulfonium tetrakis(pentafluorophenyl)borate, and the like.

[0020] Examples of the above aromatic iodonium salts 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.

[0021] Examples of the above-mentioned aromatic diazonium salts include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis(pentafluorophenyl)borate.

[0022] Examples of the above aromatic ammonium salts 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.

[0023] Examples of the above (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe salts include (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluorophosphate, (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluoroantimonate, (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) tetrafluoroborate, and (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) tetrakis(pentafluorophenyl)borate.

[0024] Examples of the above-mentioned nonionic photoacid-generating photocationic polymerization initiators include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenolsulfonic acid esters, diazonaphthoquinone, and N-hydroxyimidosulfonate.

[0025] Examples of commercially available photocationic polymerization initiators include those manufactured by Midori Chemical Co., Ltd., Union Carbide Corporation, ADEKA Corporation, 3M Corporation, BASF Corporation, Solvay Corporation, and Sunapro Corporation. Examples of photocationic polymerization initiators manufactured by Midori Chemical Co., Ltd. include DTS-200. Examples of photocationic polymerization initiators from Union Carbide include UVI6990 and UVI6974. Examples of the photocationic polymerization initiators manufactured by ADEKA mentioned above include SP-150 and SP-170. Examples of the 3M photocationic polymerization initiators mentioned above include FC-508 and FC-512. Examples of photocationic polymerization initiators manufactured by BASF include IRGACURE261 and IRGACURE290. Examples of photocationic polymerization initiators from Solvay include PI2074. Examples of photocationic polymerization initiators manufactured by Sunapro include CPI-100P, CPI-200K, and CPI-210S.

[0026] The preferred lower limit for the content of the above-mentioned photocationic polymerization initiator is 0.01 parts by mass and the preferred upper limit is 10 parts by mass, based on 100 parts by mass of the total of the above-mentioned curable resin and the low-dielectric polymer according to the present invention. When the content of the above-mentioned photocationic polymerization initiator is 0.01 parts by mass or more, the resulting resin composition for display elements will have superior photocurability. When the content of the above-mentioned photocationic polymerization initiator is 10 parts by mass or less, the curing reaction of the resulting resin composition for display elements will not be too fast, resulting in superior workability and a more uniform cured product. A more preferred lower limit for the content of the above-mentioned photocationic polymerization initiator is 0.05 parts by mass and a more preferred upper limit is 5 parts by mass.

[0027] The resin composition for display elements of the present invention preferably further contains a sensitizer. The sensitizer plays a role in further improving the polymerization initiation efficiency of the photocationic polymerization initiator and further accelerating the curing reaction of the resin composition for display elements of the present invention.

[0028] Examples of the sensitizers mentioned above include anthracene compounds, thioxanthone compounds, 2,2-dimethoxy-1,2-diphenylethane-1-one, benzophenone, 2,4-dichlorobenzophenone, o-methyl benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide. Examples of the above anthracene compounds include 9,10-dibutoxyanthracene. Examples of the thioxanthone compounds mentioned above include 2,4-diethylthioxanthone.

[0029] The preferred lower limit for the content of the above-mentioned sensitizer is 0.01 parts by mass and the preferred upper limit is 3 parts by mass, based on 100 parts by mass of the total of the above-mentioned curable resin and the low-dielectric polymer according to the present invention. When the content of the above-mentioned sensitizer is 0.01 parts by mass or more, the sensitizing effect is more pronounced. When the content of the above-mentioned sensitizer is 3 parts by mass or less, light can be transmitted to deeper parts without absorption becoming too large. A more preferred lower limit for the content of the above-mentioned sensitizer is 0.1 parts by mass and a more preferred upper limit is 1 part by mass.

[0030] The resin composition for display elements of the present invention contains at least one polymer selected from the group consisting of low dielectric polymers according to the present invention, namely hydrogenated petroleum resins and cycloolefin polymers. By combining the cationic polymerizable compound according to the present invention with the low dielectric polymer according to the present invention in the amount described later, the resin composition for display elements according to the present invention will have excellent low dielectric properties without impairing the heat resistance of the cured product.

[0031] Examples of the above-mentioned hydrogenated petroleum resins include hydrogenated petroleum resins such as aliphatic (C5) petroleum resins, aromatic (C9) petroleum resins, C5 / C9 copolymer petroleum resins, and alicyclic petroleum resins. Examples of commercially available hydrogenated petroleum resins include Alcon P140 (manufactured by Arakawa Chemical Industries, Ltd.), Alcon P90 (manufactured by Arakawa Chemical Industries, Ltd.), Alcon P100 (manufactured by Arakawa Chemical Industries, Ltd.), S-100 (manufactured by Idemitsu Kosan Co., Ltd.), S-110 (manufactured by Idemitsu Kosan Co., Ltd.), and P-100 (manufactured by Idemitsu Kosan Co., Ltd.).

[0032] The above-mentioned cycloolefin polymer may be a homopolymer of cycloolefin monomers, or it may be a copolymer of the cycloolefin monomer and other copolymer components. Examples of the above-mentioned cycloolefin monomers include cyclopentene, cyclohexene, cycloheptene, norbornene, tetracyclododecene, cyclopentadiene, dicyclopentadiene, cyclohexadiene, cyclooctadiene, and tricycloundeca-4-ene. Other copolymerization components include, for example, ethylene, propylene, 1-butene, isobutene, pentene, 1-hexene, 1-heptene, 3-heptene, 1-octene, 1-nonene, vinylcyclohexane, and the like. Examples of commercially available cycloolefin polymers include Zeonor 1020R (manufactured by Nippon Zeon Co., Ltd.), Zeonor 1060R (manufactured by Nippon Zeon Co., Ltd.), Topas 6013M-07 (manufactured by Polyplastics Co., Ltd.), Topas 5013L-10 (manufactured by Polyplastics Co., Ltd.), and Topas 8007S-04 (manufactured by Polyplastics Co., Ltd.).

[0033] The lower limit of the content of the low dielectric polymer according to the present invention in a total of 100 parts by mass of the above-mentioned curable resin and the low dielectric polymer according to the present invention is 5.1 parts by mass, and the upper limit is 15.0 parts by mass. When the content of the low dielectric polymer according to the present invention is 5.1 parts by mass or more, the resin composition for display elements of the present invention has excellent coatability, and the cured product has excellent low dielectric properties and discoloration prevention. When the content of the low dielectric polymer according to the present invention is 15.0 parts by mass or less, the cured product of the resin composition for display elements of the present invention has excellent heat resistance. The preferred lower limit of the content of the low dielectric polymer according to the present invention is 9.1 parts by mass, and the preferred upper limit is 12.0 parts by mass.

[0034] The preferred lower limit for the total content of the curable resin and the low dielectric polymer according to the present invention in 100 parts by mass of the resin composition for display elements of the present invention is 85 parts by mass, and the preferred upper limit is 98 parts by mass. By having the total content of the curable resin and the low dielectric polymer according to the present invention within this range, the resulting resin composition for display elements will have superior curability and adhesion.

[0035] The resin composition for display elements of the present invention preferably contains a stabilizer. By including the stabilizer, the resulting resin composition for display elements has superior storage stability.

[0036] Examples of the above-mentioned stabilizers include triethanolamine, benzylamine, and triglycidyl-p-aminophenol.

[0037] The preferred lower limit for the content of the above stabilizer is 0.005 parts by mass and the preferred upper limit is 0.05 parts by mass, based on 100 parts by mass of the total of the above curable resin and the low dielectric polymer according to the present invention. By having the content of the above stabilizer within this range, the resulting resin composition for display elements will have superior storage stability while maintaining excellent curability. A more preferred lower limit for the content of the above stabilizer is 0.008 parts by mass and a preferred upper limit is 0.03 parts by mass.

[0038] The resin composition for display elements of the present invention may further contain a surface modifier. By including the above-mentioned surface modifier, the surface tension of the resin composition for display elements of the present invention can be adjusted to impart flatness to the coating film. Examples of the surface modifiers mentioned above include surfactants and leveling agents.

[0039] Examples of the surface modifiers mentioned above include silicone-based, acrylic-based, and fluorine-based materials. Examples of commercially available surface conditioning agents include those manufactured by Bic Chemie Co., Ltd. and AGC Seimi Chemical Co., Ltd. Examples of surface conditioning agents manufactured by BYK-Chemie include BYK-330, BYK-340, and BYK-345. Examples of surface conditioning agents manufactured by AGC Seimi Chemical Co., Ltd. include Surflon S-611.

[0040] The content of the above surface modifier is preferably 0.1 parts by mass and preferably 1 part by mass per 100 parts by mass of the total of the above curable resin and the low dielectric polymer according to the present invention. Having the content of the above surface modifier within this range makes it easier to adjust the surface tension of the resulting resin composition for display elements. A more preferable lower limit for the content of the above surface modifier is 0.3 parts by mass and a more preferable upper limit is 0.8 parts by mass.

[0041] The resin composition for display elements of the present invention may contain a thermosetting agent to the extent that it does not hinder the objectives of the present invention. Examples of the above-mentioned thermosetting agents include hydrazide compounds, imidazole derivatives, acid anhydrides, dicyandiamides, guanidine derivatives, modified aliphatic polyamines, and addition products of epoxy resins with various amines. Examples of the above-mentioned hydrazide compounds include 1,3-bis(hydrazinocarbonoethyl)-5-isopropylhydantoin, sebacate dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, and malonic acid dihydrazide. Examples of the above-mentioned 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)-adipoamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2-phenyl-4,5-dihydroxymethylimidazole. Examples of the above-mentioned acid anhydrides include tetrahydrophthalic anhydride and ethylene glycol bis(anhydrotrimellitate).

[0042] Examples of commercially available thermosetting agents include those manufactured by Otsuka Chemical Co., Ltd. and those manufactured by Ajinomoto Fine Techno Co., Ltd. Examples of thermosetting agents manufactured by Otsuka Chemical Co., Ltd. include SDH and ADH. Examples of the thermosetting agents manufactured by Ajinomoto Fine Techno Co., Ltd. include Amicure VDH, Amicure VDH-J, and Amicure UDH.

[0043] The content of the above-mentioned thermosetting agent is preferably 0.5 parts by mass and preferably 30 parts by mass relative to 100 parts by mass of the total of the above-mentioned curable resin and the low-dielectric polymer according to the present invention. When the content of the above-mentioned thermosetting agent is within this range, the resulting resin composition for display elements maintains excellent storage stability while exhibiting superior thermosetting properties. A more preferable lower limit for the content of the above-mentioned thermosetting agent is 1 part by mass and a more preferable upper limit is 15 parts by mass.

[0044] The resin composition for display elements of the present invention may further contain a silane coupling agent. The silane coupling agent serves to improve the adhesion between the resin composition for display elements of the present invention and a substrate or the like.

[0045] Examples of the silane coupling agents mentioned above include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatetopropyltrimethoxysilane.

[0046] The preferred lower limit for the silane coupling agent content is 0.1 parts by mass and the preferred upper limit is 10 parts by mass, relative to 100 parts by mass of the total of the curable resin and the low dielectric polymer according to the present invention. This range of silane coupling agent content provides superior effectiveness in improving the adhesion of the resulting resin composition for display elements while suppressing bleed-out due to excess silane coupling agent. A more preferred lower limit for the silane coupling agent content is 0.5 parts by mass and a more preferred upper limit is 5 parts by mass.

[0047] The resin composition for display elements of the present invention may contain a curing retarder. By including the curing retarder, the pot life of the resulting resin composition for display elements can be extended.

[0048] Examples of the curing retarders mentioned above include polyether compounds. Examples of the polyether compounds mentioned above include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and crown ether compounds. Among these, crown ether compounds are preferred.

[0049] The content of the curing retarder described above is preferably 0.05 parts by mass and preferably 5.0 parts by mass per 100 parts by mass of the total of the curable resin and the low dielectric polymer according to the present invention. By having the content of the curing retarder in this range, the generation of outgassing when curing the resulting resin composition for display elements can be suppressed while exhibiting a greater delaying effect. A more preferable lower limit for the content of the curing retarder is 0.1 parts by mass and a more preferable upper limit is 3.0 parts by mass.

[0050] The resin composition for display elements of the present invention may contain a compound or ion exchange resin that reacts with the acid generated in the composition, to the extent that it does not hinder the objectives of the present invention.

[0051] Compounds that react with the acid generated in the above composition include substances that neutralize the acid, such as alkali metal or alkaline earth metal carbonates or bicarbonates. Specifically, calcium carbonate, calcium bicarbonate, sodium carbonate, sodium bicarbonate, etc., can be used.

[0052] As the ion exchange resin mentioned above, any of the following types can be used: cation exchange type, anion exchange type, or both ion exchange type. However, a cation exchange type or both ion exchange type that can adsorb chloride ions is particularly preferred.

[0053] Furthermore, the resin composition for the display element of the present invention may optionally contain various known additives such as fillers, reinforcing agents, softeners, plasticizers, viscosity modifiers, and ultraviolet absorbers.

[0054] Methods for producing the resin composition for display elements of the present invention include, for example, a method of mixing the curable resin, the photocationic polymerization initiator, the low dielectric polymer according to the present invention, and additives such as sensitizers added as needed, using a mixer such as a homodisperser, homomixer, universal mixer, planetary mixer, kneader, or three-roll mixer.

[0055] The resin composition for display elements of the present invention has a preferred lower limit of 3 mPa·s and a preferred upper limit of 30 mPa·s for viscosity, as measured using an E-type viscometer at 25°C and 100 rpm. Having the viscosity at 25°C within this range results in superior coatability for the resin composition for display elements of the present invention. A more preferred lower limit of 10 mPa·s and a more preferred upper limit of 20 mPa·s for viscosity of the resin composition for display elements of the present invention are also present.

[0056] The resin composition for display elements of the present invention has a preferred upper limit of dielectric constant of 2.60 for the cured product, measured under conditions of 25°C and 100kHz. Because the dielectric constant of the cured product is 2.60 or less, the resin composition for display elements of the present invention can be suitably used as a encapsulant for display elements in the manufacture of display elements such as organic EL display elements equipped with touch panels. The preferred upper limit of dielectric constant of the cured product is 2.50. Furthermore, there is no particular preferred lower limit for the dielectric constant of the above-mentioned cured product, but the practical lower limit is 2.20. The above-mentioned "dielectric constant" can be measured using a dielectric constant measuring device. For example, to measure the dielectric constant of a cured material, a resin composition for display elements is applied to a PET film to a thickness of 100 μm, and then, in a dry chamber with a dew point of -50°C or lower, light with a wavelength of 395 nm is applied using an LED UV lamp at an illuminance of 1000 mW / cm². 2 3000 mJ / cm 2 It can be obtained by irradiation.

[0057] The resin composition for display elements of the present invention has a preferred lower limit for the glass transition temperature of the cured product of 80°C. A glass transition temperature of 80°C or higher allows the resin composition for display elements of the present invention to be more suitably used in applications requiring heat resistance. A preferred lower limit for the glass transition temperature of the cured product is 90°C, and a more preferred lower limit is 100°C. Furthermore, there is no particular preferred upper limit for the glass transition temperature of the cured product, but the practical upper limit is 200°C. In this specification, the "glass transition temperature" refers to the temperature at which a maximum of loss tangent (tanδ) obtained by dynamic viscoelasticity measurement occurs, specifically the temperature at which a maximum due to micro-Brownian motion appears. This temperature can be measured by conventionally known methods using a viscoelasticity measuring device. Furthermore, the cured material for which the glass transition temperature is measured is a resin composition for display elements exposed to light of 395 nm wavelength at an illuminance of 1000 mW / cm using an LED UV lamp. 2 3000 mJ / cm 2 It can be obtained by irradiation.

[0058] The resin composition for display elements of the present invention is suitably used in the manufacture of display elements equipped with capacitive touch panels, and is particularly suitably used as a encapsulant for organic EL display elements. [Effects of the Invention]

[0059] According to the present invention, it is possible to provide a resin composition for display elements that has excellent coatability and whose cured product has excellent low dielectric properties and heat resistance. [Modes for carrying out the invention]

[0060] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0061] (Examples 1-4, Comparative Examples 1-5) Resin compositions for display elements in Examples 1-4 and Comparative Examples 1-5 were prepared by uniformly stirring and mixing each material at a stirring speed of 3000 rpm using a homodisperser-type stirrer, according to the mixing ratios listed in Table 1. A Homodisperser L-type (manufactured by Primix Corporation) was used as the homodisperser-type stirrer.

[0062] <Rating> The following evaluations were performed on the obtained resin compositions for display elements. The results are shown in Table 1.

[0063] (Applicability) The viscosity of the obtained resin composition for display elements was measured using an E-type viscometer with a CP1 type cone plate at 25°C and 100 rpm. A VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) was used as the E-type viscometer. Coatability was evaluated according to the following criteria. ○: When the viscosity is between 3 mPa·s and 20 mPa·s △: When viscosity exceeds 20 mPa·s but is 30 mPa·s or less. ×: If the viscosity is less than 3 mPa·s or greater than 30 mPa·s

[0064] (Low dielectric properties of cured products) The obtained resin composition for the display element was coated onto a PET film to a thickness of 100 μm, and then exposed to light with a wavelength of 395 nm at an illuminance of 1000 mW / cm² using an LED UV lamp in a dry chamber with a dew point of -50°C or lower. 2 3000 mJ / cm 2 Cured material was obtained by irradiation. An SQ series LED UV lamp (manufactured by Quark Technology, Inc.) was used. Subsequently, gold electrodes were vacuum-deposited onto both sides of the obtained cured material in a circular shape with a diameter of 2 cm and a thickness of 0.1 μm, so as to face each other, to prepare a test specimen for dielectric constant measurement. The dielectric constant of the obtained test specimen was measured using a dielectric constant measuring device under conditions of 25°C and 100 kHz. A 1260 impedance analyzer (manufactured by Solartron, Inc.) and a 1296 dielectric constant measuring interface (manufactured by Solartron, Inc.) were used as the dielectric constant measuring devices. The low dielectric properties of the cured material were evaluated according to the following criteria. ○: When the dielectric constant is 2.60 or less △: When the dielectric constant is greater than 2.60 and less than or equal to 3.00 ×: When the dielectric constant exceeds 3.00

[0065] (Heat resistance of the cured product) The obtained resin composition for display elements was exposed to light with a wavelength of 395 nm using an LED UV lamp at an illuminance of 1000 mW / cm². 2 3000 mJ / cm 2 By irradiation, a cured material measuring 20 mm in length, 5 mm in width, and 0.3 mm in thickness was obtained. The dynamic viscoelasticity of the obtained cured material was measured using a dynamic viscoelasticity measuring device (IT Measurement Control Co., Ltd., "DVA-200") in the temperature range of 0°C to 200°C, at a heating rate of 10°C / min, and a frequency of 10 Hz. The temperature at which the loss tangent (tanδ) was maximized was determined as the glass transition temperature. The heat resistance of the cured material was evaluated according to the following criteria. ○: When the glass transition temperature is 80°C or higher △: When the glass transition temperature is between 60°C and 80°C. ×: If the glass transition temperature is less than 60°C

[0066] (Discoloration prevention of hardened material) The obtained resin composition for display elements was exposed to light with a wavelength of 395 nm using an LED UV lamp at an illuminance of 1000 mW / cm². 2 3000 mJ / cm 2 Test specimens were obtained by irradiation. The obtained test specimens were subjected to a spectrophotometer (Hitachi High-Tech Science Corporation, "U-3900") to measure transmittance at wavelengths from 350 nm to 800 nm, and the Yellow Index (YI) value was derived. The discoloration prevention properties of the cured material were evaluated according to the following criteria. ○: If the YI value is less than 0.8 △: If the YI value is 0.8 or greater and less than 1 ×: If the YI value is 1 or greater

[0067] [Table 1] [Industrial applicability]

[0068] According to the present invention, it is possible to provide a resin composition for display elements that has excellent coatability and whose cured product has excellent low dielectric properties and heat resistance.

Claims

1. A resin composition for display elements containing a curable resin and a photocationic polymerization initiator, The curable resin comprises at least one selected from the group consisting of a cationic polymerizable compound having a vinyl group, a cationic polymerizable compound having an isopropenyl group, and a cationic polymerizable compound having a vinyl ether group. The resin composition for the display element further contains at least one polymer selected from the group consisting of hydrogenated petroleum resins and cycloolefin polymers. The content of at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer in a total of 100 parts by mass of the curable resin and at least one polymer selected from the group consisting of hydrogenated petroleum resin and cycloolefin polymer is 5.1 parts by mass or more and 15.0 parts by mass or less. A resin composition for display elements characterized by the following features.

2. The resin composition for a display element according to claim 1, wherein the dielectric constant of the cured product measured under conditions of 25°C and 100kHz is 2.60 or less.

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