Sealant for liquid crystal elements

Abstract

An object of the present invention is to provide a sealant for liquid crystal devices that has excellent adhesive properties and moisture-proofing properties and that exhibits a low modulus of elasticity after curing. The present invention provides a sealant for liquid crystal elements containing a curable resin, a polymerization initiator, and a heat-curing agent, wherein the curable resin contains an epoxy compound and a (meth)acrylic compound, the epoxy compound contains a bisphenol-type epoxy compound and an isocyanuric compound having an epoxy group, and the content of the isocyanuric compound having an epoxy group is 0.1 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the bisphenol-type epoxy compound.

Description

[Technical Field]

[0001] The present invention relates to a sealant for liquid crystal devices. [Background technology]

[0002] In recent years, liquid crystal display elements have been widely used as display elements characterized by their thinness, light weight, low power consumption, etc. Furthermore, liquid crystal light control elements using liquid crystal materials have been widely used as light control elements whose light transmittance changes when a voltage is applied. In such liquid crystal display elements and liquid crystal light control elements, a sealant is usually used for bonding various components and sealing the liquid crystal. For example, a liquid crystal dropping method using a sealant, as disclosed in Patent Documents 1 and 2, is used as a manufacturing method for liquid crystal display elements from the viewpoint of shortening takt time and optimizing the amount of liquid crystal used. In the dropping method, a sealant is first applied to one of two electrode-attached substrates to form a frame-shaped seal pattern. Next, while the sealant is still uncured, minute droplets of liquid crystal are dropped into the seal frame of the substrate, and the other substrate is then superimposed under vacuum, and the sealant is cured to produce a liquid crystal display element. This dropping method is currently the mainstream method for manufacturing liquid crystal display elements. Furthermore, for example, Patent Document 3 discloses the use of a material containing an epoxy compound as a sealant that surrounds the liquid crystal layer of a light control unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-133794 [Patent Document 2] International Publication No. 02 / 092718 [Patent Document 3] Patent Publication No. 2021-117456 Summary of the Invention [Problem to be solved by the invention]

[0004] In particular, sealants for liquid crystal display elements used in high-end models are increasingly required to have adhesive properties (especially adhesive properties to both glass and alignment films) and moisture-proof properties that prevent water from penetrating from the outside. Furthermore, in recent years, devices using light-adjusting elements are increasingly required to be reliable when operated under high-temperature and high-humidity environments. Meanwhile, in large displays and large devices using light-adjusting elements, warping and bending are likely to occur due to the weight of the substrates after bonding the substrates with a sealant. To prevent peeling and display defects caused by such warping and bending, sealants are also required to have a low modulus of elasticity after curing. However, because these properties are in a trade-off relationship, it has been difficult to prepare a sealant for liquid crystal elements that has excellent adhesive properties and moisture-proof properties and also has a low modulus of elasticity after curing.

[0005] An object of the present invention is to provide a sealant for liquid crystal devices that has excellent adhesive properties and moisture-proofing properties and that exhibits a low modulus of elasticity after curing. [Means for solving the problem]

[0006] Disclosure 1 relates to a sealant for liquid crystal elements containing a curable resin, a polymerization initiator, and a heat curing agent, wherein the curable resin contains an epoxy compound and a (meth)acrylic compound, the epoxy compound contains a bisphenol-type epoxy compound and an isocyanuric compound having an epoxy group, and the content of the isocyanuric compound having an epoxy group relative to 100 parts by mass of the bisphenol-type epoxy compound is 0.1 parts by mass or more and 25 parts by mass or less. Disclosure 2 relates to the sealant for liquid crystal devices of Disclosure 1, wherein the isocyanuric compound having an epoxy group includes at least one selected from the group consisting of monoallyl diglycidyl isocyanurate and diallyl monoglycidyl isocyanurate. Disclosure 3 is the sealant for liquid crystal devices according to Disclosure 1 or 2, wherein the (meth)acrylic compound contains a compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule. Disclosure 4 is the sealant for a liquid crystal device according to Disclosure 1, 2, or 3, further containing an organic filler. The present disclosure 5 is the sealant for a liquid crystal device according to the present disclosure 1, 2, 3 or 4, further comprising a silane coupling agent. The present invention will be described in detail below.

[0007] The present inventors have investigated the use of a sealant for liquid crystal devices containing an epoxy compound and a (meth)acrylic compound as a curable resin in a combination of a bisphenol-type epoxy compound and an isocyanuric compound having an epoxy group in a specific content ratio, and have found that a sealant for liquid crystal devices having excellent adhesive properties and moisture-proofing properties and a low elastic modulus after curing can be obtained, thereby completing the present invention.

[0008] The sealant for liquid crystal elements of the present invention contains a curable resin. The curable resin includes an epoxy compound and a (meth)acrylic compound. In this specification, the term "(meth)acrylic" refers to acrylic or methacrylic, and the term "(meth)acrylic compound" refers to a compound having a (meth)acryloyl group, excluding partially (meth)acrylic-modified epoxy compounds described below.

[0009] The epoxy compound includes a bisphenol-type epoxy compound and an isocyanuric compound having an epoxy group. By using the bisphenol-type epoxy compound and the isocyanuric compound having an epoxy group in combination so as to have the content described below, the sealant for liquid crystal elements of the present invention has excellent adhesion and moisture-proofing properties and exhibits a low elastic modulus after curing.

[0010] Examples of the bisphenol type epoxy compound include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol E type epoxy compounds, bisphenol S type epoxy compounds, and 2,2'-diallylbisphenol A type epoxy compounds. Furthermore, as the bisphenol type epoxy compound, a partially (meth)acrylic modified bisphenol type epoxy compound may be used. Examples of the partially (meth)acrylic-modified bisphenol-type epoxy compound include partially (meth)acrylic-modified bisphenol A-type epoxy compounds, partially (meth)acrylic-modified bisphenol F-type epoxy compounds, and partially (meth)acrylic-modified bisphenol E-type epoxy compounds. In this specification, the term "partially (meth)acrylic-modified epoxy compound" refers to a compound having one or more epoxy groups and one or more (meth)acryloyl groups in one molecule, which is obtained by reacting some of the epoxy groups of an epoxy compound having two or more epoxy groups in one molecule with (meth)acrylic acid. In addition, in this specification, the term "(meth)acryloyl" refers to acryloyl or methacryloyl.

[0011] The preferred lower limit of the content of the bisphenol epoxy compound in 100 parts by mass of the total curable resin is 10 parts by mass, and the preferred upper limit is 40 parts by mass. When the content of the bisphenol epoxy compound is 10 parts by mass or more, the resulting sealant for liquid crystal devices has superior adhesive properties. When the content of the bisphenol epoxy compound is 40 parts by mass or less, the resulting sealant for liquid crystal devices has superior moisture permeation prevention properties and a lower elastic modulus after curing. The more preferred lower limit of the content of the bisphenol epoxy compound is 20 parts by mass, and the more preferred upper limit is 30 parts by mass.

[0012] The isocyanuric compound having an epoxy group has one or more epoxy groups in one molecule, and preferably has three or less epoxy groups in one molecule, and more preferably has one or two epoxy groups in one molecule.

[0013] Specific examples of the isocyanuric compound having an epoxy group include monoallyl diglycidyl isocyanurate, diallyl monoglycidyl isocyanurate, triglycidyl isocyanurate, etc. Among these, the isocyanuric compound having an epoxy group preferably includes at least one selected from the group consisting of monoallyl diglycidyl isocyanurate and diallyl monoglycidyl isocyanurate, since the resulting sealant for liquid crystal elements has an excellent effect of achieving both adhesiveness and moisture permeation prevention properties.

[0014] The lower limit of the content of the isocyanuric compound having an epoxy group relative to 100 parts by mass of the bisphenol-type epoxy compound is 0.1 parts by mass, and the upper limit is 25 parts by mass. When the content of the isocyanuric compound having an epoxy group relative to 100 parts by mass of the bisphenol-type epoxy compound is 0.1 parts by mass or more, the sealant for liquid crystal elements of the present invention has a low elastic modulus after curing. When the content of the isocyanuric compound having an epoxy group relative to 100 parts by mass of the bisphenol-type epoxy compound is 25 parts by mass or less, the sealant for liquid crystal elements of the present invention has excellent adhesion and moisture-proofing properties. The lower limit of the content of the isocyanuric compound having an epoxy group relative to 100 parts by mass of the bisphenol-type epoxy compound is preferably 1 part by mass, and the upper limit is preferably 15 parts by mass, more preferably 4 parts by mass, and more preferably 11 parts by mass.

[0015] Examples of the (meth)acrylic compound include (meth)acrylic acid ester compounds, epoxy (meth)acrylates, and urethane (meth)acrylates. In this specification, the term "(meth)acrylate" refers to acrylate or methacrylate, and the term "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have reacted with (meth)acrylic acid.

[0016] Examples of the monofunctional (meth)acrylic acid ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and isomyristyl (meth)acrylate. (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, bicyclopentenyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxy Ethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethyl carbitol (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoroethylene glycol (meth)acrylate Examples of such acrylates include fluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, imide (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, and glycidyl (meth)acrylate.

[0017] Furthermore, examples of the bifunctional (meth)acrylic acid ester compounds include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, Examples of suitable bisphenol A di(meth)acrylates include butyl di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-added bisphenol A di(meth)acrylate, propylene oxide-added bisphenol A di(meth)acrylate, ethylene oxide-added bisphenol F di(meth)acrylate, dimethyloldicyclopentadienyl di(meth)acrylate, ethylene oxide-modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polycaprolactone diol di(meth)acrylate, and polybutadiene diol di(meth)acrylate.

[0018] Furthermore, examples of the (meth)acrylic acid ester compounds having three or more functional groups include trimethylolpropane tri(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, ethylene oxide-added isocyanuric acid tri(meth)acrylate, glycerin tri(meth)acrylate, propylene oxide-added glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(meth)acryloyloxyethyl phosphate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0019] The epoxy (meth)acrylate may be, for example, one obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a basic catalyst according to a conventional method.

[0020] Examples of epoxy compounds that can be used as raw materials for synthesizing the above-mentioned epoxy (meth)acrylates include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol E type epoxy compounds, bisphenol S type epoxy compounds, 2,2'-diallyl bisphenol A type epoxy compounds, hydrogenated bisphenol type epoxy compounds, propylene oxide-added bisphenol A type epoxy compounds, resorcinol type epoxy compounds, biphenyl type epoxy compounds, sulfide type epoxy compounds, diphenyl ether type epoxy compounds, dicyclopentadiene type epoxy compounds, naphthalene type epoxy compounds, phenol novolac type epoxy compounds, o-cresol novolac type epoxy compounds, dicyclopentadiene novolac type epoxy compounds, biphenyl novolac type epoxy compounds, naphthalene phenol novolac type epoxy compounds, glycidylamine type epoxy compounds, alkyl polyol type epoxy compounds, rubber-modified type epoxy compounds, and glycidyl ester compounds.

[0021] Among the above-mentioned epoxy (meth)acrylates, commercially available ones include, for example, epoxy (meth)acrylate manufactured by Daicel Allnex Corporation, epoxy (meth)acrylate manufactured by Shin-Nakamura Chemical Co., Ltd., epoxy (meth)acrylate manufactured by Kyoeisha Chemical Co., Ltd., and epoxy (meth)acrylate manufactured by Nagase ChemteX Corporation. Examples of the epoxy (meth)acrylates manufactured by Daicel-Allnex include EBECRYL860, EBECRYL3200, EBECRYL3201, EBECRYL3412, EBECRYL3600, EBECRYL3700, EBECRYL3701, EBECRYL3702, EBECRYL3703, EBECRYL3708, EBECRYL3800, EBECRYL6040, EBECRYL RDX63182, and KRM8076. Examples of the epoxy (meth)acrylates manufactured by Shin-Nakamura Chemical Co., Ltd. include EA-1010, EA-1020, EA-5323, EA-5520, EA-CHD, and EMA-1020. Examples of the epoxy (meth)acrylates manufactured by Kyoeisha Chemical Co., Ltd. include Epoxy Ester M-600A, Epoxy Ester 40EM, Epoxy Ester 70PA, Epoxy Ester 200PA, Epoxy Ester 80MFA, Epoxy Ester 3002M, Epoxy Ester 3002A, Epoxy Ester 1600A, Epoxy Ester 3000M, Epoxy Ester 3000A, Epoxy Ester 200EA, and Epoxy Ester 400EA. Examples of the epoxy (meth)acrylates manufactured by Nagase ChemteX Corporation include Denacol Acrylate DA-141, Denacol Acrylate DA-314, and Denacol Acrylate DA-911.

[0022] The urethane (meth)acrylate can be obtained, for example, by reacting an isocyanate compound with a (meth)acrylic acid derivative having a hydroxyl group in the presence of a catalytic amount of a tin compound.

[0023] Examples of isocyanate compounds that can be used as raw materials for the urethane (meth)acrylate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatephenyl)thiophosphate, tetramethylxylylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0024] Furthermore, as the isocyanate compound that is the raw material for the urethane (meth)acrylate, a chain-extended isocyanate compound obtained by reacting a polyol with an excess of an isocyanate compound can also be used. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0025] Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl (meth)acrylates, mono(meth)acrylates of dihydric alcohols, mono(meth)acrylates or di(meth)acrylates of trihydric alcohols, and epoxy (meth)acrylates. Examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of the trihydric alcohol include trimethylolethane, trimethylolpropane, and glycerin. Examples of the epoxy(meth)acrylate include bisphenol A type epoxy(meth)acrylate.

[0026] Among the above-mentioned urethane (meth)acrylates, commercially available ones include, for example, urethane (meth)acrylate manufactured by Toagosei Co., Ltd., urethane (meth)acrylate manufactured by Daicel-Allnex Corporation, urethane (meth)acrylate manufactured by Negami Chemical Industries, Ltd., urethane (meth)acrylate manufactured by Shin-Nakamura Chemical Co., Ltd., and urethane (meth)acrylate manufactured by Kyoeisha Chemical Co., Ltd. Examples of the urethane (meth)acrylates manufactured by Toagosei Co., Ltd. include M-1100, M-1200, M-1210, and M-1600. Examples of the urethane (meth)acrylates manufactured by Daicel-Allnex include EBECRYL210, EBECRYL220, EBECRYL230, EBECRYL270, EBECRYL1290, EBECRYL2220, EBECRYL4827, EBECRYL4842, EBECRYL4858, EBECRYL5129, EBECRYL6700, EBECRYL8402, EBECRYL8803, EBECRYL8804, EBECRYL8807, and EBECRYL9260. Examples of urethane (meth)acrylates manufactured by Negami Chemical Industrial Co., Ltd. include Art Resin UN-330, Art Resin SH-500B, Art Resin UN-1200TPK, Art Resin UN-1255, Art Resin UN-3320HB, Art Resin UN-7100, Art Resin UN-9000A, and Art Resin UN-9000H. Examples of the urethane (meth)acrylates manufactured by Shin-Nakamura Chemical Co., Ltd. include U-2HA, U-2PHA, U-3HA, U-4HA, U-6H, U-6HA, U-6LPA, U-10H, U-15HA, U-108, U-108A, U-122A, U-122P, U-324A, U-340A, U-340P, U-1084A, U-2061BA, UA-340P, UA-4000, UA-4100, UA-4200, UA-4400, UA-5201P, UA-7100, UA-7200, and UA-W2A. Examples of the urethane (meth)acrylates manufactured by Kyoeisha Chemical Co., Ltd. include AH-600, AI-600, AT-600, UA-101I, UA-101T, UA-306H, UA-306I, and UA-306T.

[0027] Among these, the (meth)acrylic compound preferably contains a hydrogen-bonding functional group to improve adhesion to the interface, more preferably contains a compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule, and particularly preferably contains 2-hydroxy-3-phenoxypropyl(meth)acrylate. The (meth)acrylic compound also preferably contains the epoxy(meth)acrylate, and more preferably contains a combination of the compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule and the epoxy(meth)acrylate.

[0028] The preferred lower limit of the content of the (meth)acrylic compound in 100 parts by mass of the total curable resin is 30 parts by mass, and the preferred upper limit is 90 parts by mass. When the content of the (meth)acrylic compound is within this range, the resulting sealant for liquid crystal devices will have superior curability and adhesive properties, and will also have excellent low liquid crystal contamination properties. The more preferred lower limit of the content of the (meth)acrylic compound is 40 parts by mass, and the more preferred upper limit is 80 parts by mass.

[0029] The preferred lower limit of the total content of the curable resin in 100 parts by mass of the sealant for liquid crystal elements of the present invention is 50 parts by mass, and the preferred upper limit is 95 parts by mass. When the total content of the curable resin is within this range, the resulting sealant for liquid crystal elements has better curability and adhesiveness. The more preferred lower limit of the total content of the curable resin is 60 parts by mass, and the more preferred upper limit is 85 parts by mass.

[0030] The sealing agent for liquid crystal elements of the present invention contains a polymerization initiator. Examples of the polymerization initiator include a photoradical polymerization initiator that generates radicals upon irradiation with light, and a thermal radical polymerization initiator that generates radicals upon heating.

[0031] Examples of the photoradical polymerization initiator include benzophenone-based compounds, acetophenone-based compounds, acylphosphine oxide-based compounds, titanocene-based compounds, oxime ester-based compounds, benzoin ether-based compounds, and thioxanthone-based compounds. Specific examples of the photoradical polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4-(4-morpholinyl)phenyl)-1-butanone, 2,2-dimethoxy-1,2-diphenylethan-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl-2-methyl-1 ... methyl-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, benzoin isopropyl ether, and the like. The photoradical polymerization initiators may be used alone or in combination of two or more.

[0032] Examples of the thermal radical polymerization initiator include those composed of an azo compound, an organic peroxide, etc. Among them, from the viewpoint of suppressing contamination of the liquid crystal, an initiator composed of an azo compound (hereinafter also referred to as "azo initiator") is preferred. The thermal radical polymerization initiators may be used alone or in combination of two or more. Among the above azo initiators, commercially available ones include, for example, VPE-0201, VPE-0401, VPE-0601, VPS-0501, VPS-1001, V-65, and V-501 (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0033] Examples of the organic peroxide include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, and peroxydicarbonates.

[0034] The content of the polymerization initiator is preferably 0.01 parts by mass at the lower limit and 10 parts by mass at the upper limit relative to 100 parts by mass of the curable resin. By using the polymerization initiator in this range, the resulting sealant for liquid crystal devices will have better storage stability and curability. The more preferred lower limit of the content of the polymerization initiator is 0.1 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0035] The sealant for liquid crystal elements of the present invention contains a heat curing agent. Examples of the heat curing agent include organic acid hydrazides, imidazole derivatives, amine compounds, polyhydric phenol compounds, acid anhydrides, etc. Among these, organic acid hydrazides are preferably used. The above-mentioned heat curing agents may be used alone or in combination of two or more kinds.

[0036] Examples of the organic acid hydrazide include sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, and malonic acid dihydrazide. Among the above organic acid hydrazides, commercially available ones include, for example, organic acid hydrazides manufactured by Otsuka Chemical Co., Ltd. and organic acid hydrazides manufactured by Ajinomoto Fine-Techno Co., Ltd. Examples of the organic acid hydrazides manufactured by Otsuka Chemical Co., Ltd. include SDH, ADH, and MDH. Examples of the organic acid hydrazides manufactured by Ajinomoto Fine-Techno Co., Inc. include Amicure VDH, Amicure VDH-J, Amicure UDH, and Amicure UDH-J.

[0037] The content of the thermosetting agent is preferably 1 part by mass at the lower limit and 50 parts by mass at the upper limit relative to 100 parts by mass of the curable resin. By setting the content of the thermosetting agent within this range, the resulting sealant for liquid crystal elements can have excellent thermosetting properties without deteriorating the application properties or storage stability. The more preferred upper limit of the content of the thermosetting agent is 30 parts by mass.

[0038] The sealant for liquid crystal elements of the present invention preferably further contains an organic filler. By containing the organic filler, the resulting sealant for liquid crystal elements has better adhesion to the alignment film and is more easily made to have a low elastic modulus after curing. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and (meth)acrylic polymer fine particles. Among these, (meth)acrylic polymer fine particles are preferred. The organic filler may have a core-shell structure.

[0039] The preferred lower limit of the average particle size of the organic filler is 0.1 μm, and the preferred upper limit is 5 μm. By having the average particle size of the organic filler in this range, it becomes easier to make the resulting sealant for liquid crystal devices have a low elastic modulus after curing while maintaining coatability, etc. The more preferred lower limit of the average particle size of the organic filler is 0.3 μm, and the more preferred upper limit is 2 μm. The average particle size of the organic filler can be measured by dispersing the organic filler in a solvent (water, organic solvent, etc.) using a particle size distribution analyzer, such as NICOMP 380ZLS (manufactured by PARTICLE SIZING SYSTEMS).

[0040] The preferred lower limit of the content of the organic filler relative to 100 parts by mass of the curable resin is 1 part by mass, and the preferred upper limit is 40 parts by mass. By having the content of the organic filler within this range, it becomes easier to obtain a sealant for liquid crystal devices that has a low elastic modulus after curing while maintaining coatability, etc. The more preferred lower limit of the content of the organic filler is 3 parts by mass, and the more preferred upper limit is 30 parts by mass.

[0041] The sealing agent for a liquid crystal element of the present invention may further contain an inorganic filler for the purposes of adjusting viscosity, further improving adhesiveness by a stress dispersion effect, improving the linear expansion coefficient, and the like.

[0042] Examples of the inorganic filler include silica, talc, glass beads, asbestos, gypsum, diatomaceous earth, smectite, bentonite, montmorillonite, sericite, activated clay, alumina, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum nitride, silicon nitride, barium sulfate, and calcium silicate.

[0043] The preferred lower limit of the content of the inorganic filler relative to 100 parts by mass of the curable resin is 10 parts by mass, and the preferred upper limit is 40 parts by mass. By having the content of the inorganic filler within this range, excellent effects such as improved adhesion can be achieved while maintaining coatability, etc. The more preferred lower limit of the content of the inorganic filler is 20 parts by mass, and the more preferred upper limit is 30 parts by mass.

[0044] The sealant for liquid crystal elements of the present invention preferably further contains a silane coupling agent. The silane coupling agent mainly serves as an adhesion aid for further improving adhesion between the sealant for liquid crystal elements and a substrate or the like.

[0045] Suitable examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-isocyanatopropyltrimethoxysilane, which are excellent in improving adhesion to the substrate and can also prevent the outflow of the curable resin into the liquid crystal. The above silane coupling agents may be used alone or in combination of two or more kinds.

[0046] The preferred lower limit of the content of the silane coupling agent relative to 100 parts by mass of the curable resin is 0.1 parts by mass, and the preferred upper limit is 5 parts by mass. By having the content of the silane coupling agent within this range, the effect of improving adhesion is more excellent. The more preferred lower limit of the content of the silane coupling agent is 0.3 parts by mass, and the more preferred upper limit is 2 parts by mass.

[0047] The sealing agent for liquid crystal elements of the present invention may further contain additives such as a light-shielding agent, a stress relaxation agent, a reactive diluent, a thixotropic agent, a spacer, a curing accelerator, an antifoaming agent, a leveling agent, and a polymerization inhibitor, as necessary.

[0048] Examples of a method for producing the sealing agent for liquid crystal elements of the present invention include a method of mixing a curable resin, a polymerization initiator, a heat curing agent, and additives such as a silane coupling agent, which are added as needed, using a mixer such as a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, or a three-roll mill.

[0049] The sealant for liquid crystal devices of the present invention is applied at a wavelength of 365 nm and an illuminance of 100 mW / cm 2The cured product obtained by irradiating the cured product with ultraviolet light for 30 seconds and then heating at 120°C for 1 hour preferably has a storage modulus at 25°C of less than 3.5 GPa. By having a storage modulus of less than 3.5 GPa, the sealant for liquid crystal elements of the present invention is excellent in preventing peeling and display defects when used in large displays or large devices using light-adjusting elements. The storage modulus is more preferably less than 3.0 GPa. From the viewpoint of adhesiveness when the adherend is bonded to another, the lower limit of the storage modulus is preferably 0.1 GPa, and more preferably 1.0 GPa. The storage modulus can be measured using a dynamic viscoelasticity measuring device (e.g., "DVA-200" manufactured by IT Measurement & Control Co., Ltd.) under the following conditions: tensile mode, test piece width 5 mm, thickness 0.35 mm, grip width 25 mm, heating rate 10°C / min, and frequency 5 Hz.

[0050] By blending conductive fine particles into the sealing agent for liquid crystal elements of the present invention, a vertically conductive material can be produced.

[0051] The conductive fine particles may be metal balls, fine resin particles with a conductive metal layer formed on the surface thereof, etc. Among these, fine resin particles with a conductive metal layer formed on the surface thereof are preferred because they have excellent elasticity and can provide conductive connection without damaging transparent substrates, etc.

[0052] The liquid crystal element obtained by using the sealant for liquid crystal elements of the present invention is preferably a liquid crystal element with a narrow frame design, specifically, the width of the frame part around the liquid crystal display unit is preferably 2 mm or less. When the liquid crystal element is produced, the application width of the sealant for a liquid crystal element of the present invention is preferably 1 mm or less. Examples of liquid crystal elements produced using the sealant for liquid crystal elements of the present invention include liquid crystal display elements and liquid crystal light control elements.

[0053] The sealant for liquid crystal elements of the present invention can be suitably used in the production of liquid crystal elements by a liquid crystal dropping method. Examples of the method for producing the liquid crystal element by the liquid crystal dropping method include the following methods. First, a process is performed in which the sealant for liquid crystal elements of the present invention is applied to a substrate by screen printing, dispenser application, or the like to form a frame-shaped seal pattern. Next, while the sealant for liquid crystal elements of the present invention is in an uncured state, minute droplets of liquid crystal are dropwise applied to the entire frame of the seal pattern, and another substrate is immediately superimposed on the substrate. After that, a liquid crystal element can be obtained by a process in which the seal pattern portion is irradiated with light such as ultraviolet light to temporarily cure the sealant for liquid crystal elements, and a process in which the temporarily cured sealant for liquid crystal elements is heated to permanently cure the sealant. [Effects of the Invention]

[0054] According to the present invention, it is possible to provide a sealant for liquid crystal devices that has excellent adhesive properties and moisture-proofing properties, and that has a low modulus of elasticity after curing. DETAILED DESCRIPTION OF THE INVENTION

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0056] (Examples 1 to 17, Comparative Examples 1 to 6) Each material was stirred in accordance with the compounding ratios shown in Tables 1 to 3 using a planetary stirring device (Thinky Corporation, "Awatori Rentaro"), and then uniformly mixed using a ceramic triple roll to obtain sealing agents for liquid crystal elements of Examples 1 to 17 and Comparative Examples 1 to 6.

[0057] <Evaluation> The obtained sealant for liquid crystal devices was evaluated as follows, and the results are shown in Tables 1 to 3.

[0058] (Adhesion to glass substrates with ITO thin film) One part by mass of spacer particles (Micropearl SP-2050, manufactured by Sekisui Chemical Co., Ltd.) with an average particle size of 5 μm was uniformly dispersed in 100 parts by mass of the obtained sealant for liquid crystal devices using a planetary stirrer. A very small amount of the sealant for liquid crystal devices with the spacer particles dispersed therein was placed in the center of a glass substrate with an ITO thin film, and another glass substrate with an ITO thin film of the same type was placed on top of it. The sealant for liquid crystal devices was spread, and a metal halide lamp was used to illuminate the surface at a wavelength of 365 nm and an illuminance of 100 mW / cm. 2 After irradiating the sealant for liquid crystal elements with ultraviolet light for 30 seconds, the sealant was cured by heating at 120°C for 1 hour to obtain an adhesive test piece. The adhesive strength (adhesion force to the glass substrate with the ITO thin film) of the obtained adhesive test piece was measured using a tension gauge. Adhesive strength is 3.0kgf / cm 2 If it is above 2.5kgf / cm, it is marked as "◎" 2 Over 3.0kgf / cm 2 If it is less than 2.5kgf / cm, mark it as "○"; 2 When the adhesion was less than 100%, it was marked as "X" and the adhesion to the glass substrate with the ITO thin film was evaluated.

[0059] (Adhesion to substrates with alignment film) An imide resin was spin-coated onto a glass substrate with an ITO thin film, pre-baked at 80°C, and then baked at 230°C to prepare a substrate with an alignment film. SE7492 (manufactured by Nissan Chemical Industries, Ltd.) was used as the imide resin. Adhesion test pieces were obtained in the same manner as in "(Adhesion to glass substrate with ITO thin film)" above, except that a substrate with an alignment film was used instead of a glass substrate with an ITO thin film. The adhesive strength (adhesion to substrate with alignment film) of the obtained adhesion test pieces was measured using a tension gauge. Adhesive strength is 2.0kgf / cm 2 If it is more than 1.5kgf / cm, it is marked as "◎" 2 Over 2.0kgf / cm 2 If it is less than 1.5kgf / cm, it is marked as "○" 2 If the adhesion was less than 100%, it was marked as "X" and the adhesiveness to the substrate with the alignment film was evaluated.

[0060] (Moisture-proof) The obtained sealant for liquid crystal devices was applied to a smooth release film using a coater to a thickness of 200 to 300 μm, and then irradiated with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm. 2 After irradiating with ultraviolet light for 30 seconds, the sealant for liquid crystal devices was cured by heating at 120°C for 1 hour to obtain a film for moisture permeability measurement. A cup for the moisture permeability test was prepared according to the method for testing moisture permeability of moisture-proof packaging materials (cup method) of JIS Z 0208, and the obtained film for moisture permeability measurement was attached to the cup, which was then placed in a constant temperature and humidity oven at 80°C and 90% RH to measure the moisture permeability. The obtained moisture permeability value was 70 g / m 2 - Less than 24 hours: "◎"; 70g / m 2 ·80g / m over 24hr 2 - Less than 24 hours: "○"; 80g / m 2 If it lasted for 24 hours or more, it was rated as "×" and the moisture permeability was evaluated.

[0061] (elastic modulus) The obtained sealant for liquid crystal devices was irradiated with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm. 2 After irradiating with ultraviolet light for 30 seconds, the sample was heated at 120°C for 1 hour to obtain a cured product. Dynamic viscoelasticity measurements were performed on the obtained cured product using a dynamic viscoelasticity measuring device under the following conditions: tension mode, test piece width 5 mm, thickness 0.35 mm, grip width 25 mm, heating rate 10°C / min, and frequency 5 Hz, and the storage modulus at 25°C was measured. The storage modulus was evaluated as follows: "A" if the storage modulus was less than 3.0 GPa, "B" if it was 3.0 GPa or more but less than 3.5 GPa, and "C" if it was 3.5 GPa or more.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3] [Industrial Applicability]

[0065] According to the present invention, it is possible to provide a sealant for liquid crystal devices that has excellent adhesive properties and moisture-proofing properties, and that has a low modulus of elasticity after curing.

Claims

1. A sealant for liquid crystal elements containing a curable resin, a polymerization initiator, and a heat curing agent, the curable resin contains an epoxy compound and a (meth)acrylic compound, The epoxy compound includes a bisphenol-type epoxy compound and an isocyanuric compound having an epoxy group, The content of the isocyanuric compound having an epoxy group relative to 100 parts by mass of the bisphenol type epoxy compound is 0.1 parts by mass or more and 25 parts by mass or less. A sealant for liquid crystal elements.

2. 2. The sealant for liquid crystal devices according to claim 1, wherein the isocyanuric compound having an epoxy group comprises at least one selected from the group consisting of monoallyl diglycidyl isocyanurate and diallyl monoglycidyl isocyanurate.

3. 3. The sealant for liquid crystal devices according to claim 1, wherein the (meth)acrylic compound comprises a compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule.

4. 3. The sealant for liquid crystal devices according to claim 1, further comprising an organic filler.

5. 3. The sealant for liquid crystal devices according to claim 1, further comprising a silane coupling agent.

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