Sealing agent for liquid crystal display element

Abstract

The purpose of the present invention is to provide a sealing agent for a liquid crystal display element which exhibits excellent transparency, adhesiveness, and moisture barrier properties. The present invention provides a sealing agent for a liquid crystal display element, the sealing agent containing a curable resin, an inorganic filler, a photoinitiator, and a heat curing agent. The sealing agent for a liquid crystal display element exhibits a haze of 60% or less in a cured material with a thickness of 100 µm, and a moisture permeability of 90 g / m2･24hr·or less in cured material with a thickness of 300 µm, which is measured in accordance with JIS Z 0208, under conditions of 80°C and 90%RH.

Description

Sealant for LCD devices

[0001] The present invention relates to a sealant for a liquid crystal display element.

[0002] In recent years, a liquid crystal dropping method using a photothermally curable sealant, as disclosed in Patent Documents 1 and 2, has been adopted as a manufacturing method for liquid crystal display elements such as liquid crystal display cells, from the viewpoints of shortening takt time and optimizing the amount of liquid crystal used. In the dropping method, a frame-shaped seal pattern is first formed by dispensing on one of two transparent substrates with electrodes. Next, while the sealant is still uncured, minute droplets of liquid crystal are dropped onto the entire frame of the transparent substrate. The other transparent substrate is then immediately bonded to the sealant, and the sealant is irradiated with ultraviolet or other light for temporary curing. The liquid crystal is then heated during liquid crystal annealing to fully cure the sealant, completing the production of the liquid crystal display element. By bonding the substrates under reduced pressure, liquid crystal display elements can be manufactured with extremely high efficiency, and this dropping method is currently the mainstream method for manufacturing liquid crystal display elements.

[0003] Japanese Patent Application Laid-Open No. 2001-133794 International Publication No. 02 / 092718

[0004] In recent years, the development of transparent displays has progressed, and accordingly, there is a demand for sealants for liquid crystal display elements that are excellent in transparency. Sealants for liquid crystal display elements usually contain inorganic fillers such as talc to improve adhesion and moisture resistance. Sealants containing such inorganic fillers have poor transparency because the inorganic fillers scatter light, making them appear cloudy. On the other hand, if the content of inorganic fillers is reduced to improve transparency, there is a risk that the adhesion and moisture resistance of the sealant to the substrate will deteriorate. Therefore, it has been difficult for conventional sealants to have excellent transparency, adhesion, and moisture resistance.

[0005] An object of the present invention is to provide a sealant for liquid crystal display elements that is excellent in transparency, adhesiveness, and moisture permeation prevention properties.

[0006] Disclosure 1 provides a sealant for liquid crystal display elements, which contains a curable resin, an inorganic filler, a photopolymerization initiator, and a heat curing agent, and which has a haze of 60% or less when cured to a thickness of 100 μm, and a moisture permeability of 90 g / m or less when cured to a thickness of 300 μm at 80° C. and 90% RH, as measured in accordance with JIS Z 0208. ２ The present disclosure is directed to a sealant for liquid crystal display elements having an adhesive strength to glass of 2.0 kgf / cm or more at 25°C when the cured product of the sealant for liquid crystal display elements is 2.0 kgf / cm or more. The present disclosure is directed to a sealant for liquid crystal display elements of the present disclosure 1 or 2, wherein the inorganic filler has a refractive index of 1.50 or more and 1.60 or less, and the difference in refractive index between the cured product of the curable resin and the inorganic filler is 0.08 or less. The present disclosure is directed to a sealant for liquid crystal display elements of the present disclosure 1, 2, or 3, wherein the inorganic filler is a silica-titania composite oxide. The present disclosure is directed to a sealant for liquid crystal display elements of the present disclosure 1, 2, 3, or 4, wherein the inorganic filler has an M value of 20 or more. The present disclosure is directed to a sealant for liquid crystal display elements of the present disclosure 1, 2, 3, or 4, wherein the thermosetting agent includes an imidazole derivative that is liquid at 25°C. The present invention is described in detail below.

[0007] The present inventors have found that a sealant for liquid crystal display elements that is excellent in transparency, adhesiveness, and moisture permeability prevention properties can be obtained by adjusting the haze of a 100 μm-thick cured product and the moisture permeability of a 300 μm-thick cured product in an environment of 80°C and 90% RH, and have thus completed the present invention.

[0008] The sealant for liquid crystal display elements of the present invention has a haze of 60% or less when cured at a thickness of 100 μm. Having a haze of 60% or less in the cured product results in the resulting liquid crystal display element having excellent optical properties. The preferred upper limit of the haze of the cured product is 40%. There is no particular preferred lower limit for the haze of the cured product, but the substantial lower limit is 1%. The haze of the cured product can be measured using a spectrometer such as an AUTOMATIC HAZE METER MODEL TC-III DPK (manufactured by Tokyo Denshoku Co., Ltd.). The cured product used for haze measurement is a sealant that is irradiated with UV light at a wavelength of 365 nm and an illuminance of 100 mW / cm using a UV irradiator. ２ The cured product is obtained by irradiating the composition with ultraviolet light of 100 μm diameter for 30 seconds through a 340 nm cut filter, followed by heating for 60 minutes at 120° C. As the UV irradiator, for example, MB1500T-3 (manufactured by Sen Special Light Sources Co., Ltd.) can be used.

[0009] The sealant for liquid crystal display elements of the present invention has a moisture permeability of 90 g / m2 at 80°C and 90% RH in a cured product having a thickness of 300 μm, as measured in accordance with JIS Z 0208. ２ The moisture permeability is 90 g / m or less. ２ By keeping the moisture permeability at 24 hours or less, the resulting liquid crystal display device will have excellent reliability. ２ 24 hours. There is no particular preferred lower limit for the moisture permeability, but the substantial lower limit is 10 g / m ２ The cured product for measuring the moisture permeability was a sealant, which was irradiated with UV light at a wavelength of 365 nm and an illuminance of 100 mW / cm using a UV irradiator. ２ The cured product has a thickness of 300 μm and is obtained by irradiating the composition with ultraviolet light of 1000 nm through a 340 nm cut filter for 30 seconds, followed by heating for 60 minutes at 120° C. As the UV irradiator, for example, MB1500T-3 (manufactured by Sen Special Light Sources Co., Ltd.) can be used.

[0010] The preferred lower limit of the adhesive strength of the cured sealant for liquid crystal display elements of the present invention to glass at 25°C is 2.0 kgf / cm. Having an adhesive strength to glass of 2.0 kgf / cm or more results in the resulting liquid crystal display element having superior reliability. There is no particular preferred upper limit to the adhesive strength to glass, but the practical upper limit is 10.0 kgf / cm. The adhesive strength to glass can be measured by the following method. Specifically, the sealant is applied in dots to one of two glass substrates so that the diameter of the dotted glass is 3 mm when the substrates are bonded together. The glass substrate with the dotted sealant and the other glass substrate are bonded together in a cross shape via the sealant. Then, using a UV irradiator, the sealant is applied at a wavelength of 365 nm and an illuminance of 100 mW / cm. ２ The sealant is cured by irradiating it with ultraviolet light of 1000 nm through a 340 nm cut filter for 30 seconds, followed by heating at 120°C for 60 minutes to obtain a test specimen. The obtained test specimen is subjected to a tensile test at 5 mm / sec using upper and lower chucks in an environment of 25°C, whereby the adhesive strength to glass can be measured. As the UV irradiator, for example, an MB1500T-3 (manufactured by Sen Special Light Sources Co., Ltd.) can be used.

[0011] The sealant for liquid crystal display elements of the present invention contains an inorganic filler. The refractive index of the inorganic filler is preferably 1.50 or more and 1.60 or less, and the absolute difference between the refractive index of the cured product of the curable resin described below and the refractive index of the inorganic filler is preferably 0.08 or less. When the refractive index of the inorganic filler is 1.50 or more and 1.60 or less, and the absolute difference between the refractive index of the cured product of the curable resin described below and the refractive index of the inorganic filler is 0.08 or less, the resulting sealant for liquid crystal display elements has excellent transparency. The lower limit of the refractive index of the inorganic filler is more preferably 1.54, and the upper limit is more preferably 1.58. Furthermore, the upper limit of the absolute difference between the refractive index of the cured product of the curable resin described below and the refractive index of the inorganic filler is more preferably 0.06, and even more preferably 0.04. The smaller the absolute difference between the refractive index of the cured product of the curable resin described below and the refractive index of the inorganic filler, the more preferable, and it is most preferably 0. Note that, in this specification, the refractive index refers to the refractive index at the sodium D line measured using an Abbe refractometer at 25°C. An example of the Abbe refractometer is the Universal Abbe refractometer ER-7MW (manufactured by ERMA). The cured product of the curable resin for measuring the refractive index can be obtained, for example, by the following method. First, a photopolymerization initiator and a heat curing agent are mixed with the curable resin to obtain a curable resin composition. The obtained curable resin composition is irradiated with UV light at a wavelength of 365 nm and an illuminance of 100 mW / cm using a UV irradiator. ２ A cured product to be used for measuring the refractive index can be obtained by irradiating the resin with ultraviolet light of 1000 nm through a 340 nm cut filter for 30 seconds, followed by heating for 60 minutes at 120° C. As the UV irradiator, for example, MB1500T-3 (manufactured by Sen Special Light Source Co., Ltd.) can be used.

[0012] Examples of the inorganic filler include silica-titania composite oxide and talc particles. Among these, silica-titania composite oxide is preferred. By including the silica-titania composite oxide, the sealant for liquid crystal display elements of the present invention has excellent transparency, adhesiveness, and moisture-proofing properties.

[0013] The inorganic filler is preferably surface-treated, and more preferably has a hydrophobic group on its surface. By having a hydrophobic group on its surface, the resulting sealant for liquid crystal display elements has better adhesion to alignment films.

[0014] When the inorganic filler has a hydrophobic group on its surface, examples of the hydrophobic group include an alkyl group having 1 to 20 carbon atoms, an epoxy group, an amino group, an alkoxyl group, a vinyl group, a (meth)acryloyl group, a sulfide group, a mercapto group, an isocyanate group, a ureido group, a pyridyl group, and a styryl group. Of these, an alkyl group having 1 to 20 carbon atoms is preferred, and a methyl group is more preferred. In this specification, the term "(meth)acryloyl" means acryloyl or methacryloyl.

[0015] The inorganic filler having hydrophobic groups on the surface thereof can be obtained by a method of treating the surface of an untreated inorganic filler (base particle) with a surface treatment agent.

[0016] Examples of the surface treatment agent used for the surface treatment of the base particle include silazane compounds, siloxane compounds, various silane coupling agents, various titanium coupling agents, various aluminum-based coupling agents, acid anhydrides, higher fatty acids, isocyanate compounds, acid chloride compounds, phosphate ester compounds, aldehyde compounds, etc. Among these, silane coupling agents are preferred because they are highly effective in improving the alignment film adhesion of the resulting sealant for liquid crystal display elements.

[0017] Examples of the silane coupling agent used as the surface treatment agent include methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, methyltrichlorosilane, butyltrichlorosilane, trifluoropropyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, 3-glycidoxypropylmethyldi ... -aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltrichlorosilane, allyltrichlorosilane, allyltrimethoxysilane, allyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-octanoylthio-1-propyltriethoxysilane, 3-ureidopropyltriethoxysilane, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, and the like.

[0018] Examples of methods for surface treating the base particles include a method in which the surface treatment agent is dissolved in an organic solvent such as alcohol or toluene, and the base particles are dispersed in the resulting solution to cause a reaction.

[0019] The preferred upper limit of the average primary particle diameter of the inorganic filler is 0.5 μm. When the average primary particle diameter of the inorganic filler is 0.5 μm or less, light scattering is suppressed, resulting in superior transparency, and the resulting sealant for liquid crystal display elements will have superior transparency. A more preferred upper limit of the average primary particle diameter of the inorganic filler is 0.4 μm. From the viewpoint of coatability and the like, a preferred lower limit of the average primary particle diameter of the inorganic filler is 0.01 μm, and a more preferred lower limit is 0.05 μm. In this specification, the average primary particle diameter refers to the average value of the major axes of 300 particles measured using a SEM-EDX measurement device. An example of the SEM-EDX measurement device is the S-4800 (manufactured by Hitachi High-Technologies Corporation).

[0020] The inorganic filler preferably has an M value lower limit of 20. When the inorganic filler has an M value of 20 or more, the resulting sealant for liquid crystal displays has superior adhesion to alignment films. The inorganic filler's M value lower limit is more preferably 22, and even more preferably 23. The upper limit of the M value of the inorganic filler is not particularly limited, and although theoretically it is 99.9, a preferred upper limit is 70, a more preferred upper limit is 50, and an even more preferred upper limit is 35. If the inorganic filler's M value exceeds 50, the viscosity and thixotropic index of the sealant containing the inorganic filler may increase, making application difficult. If the inorganic filler's M value exceeds 70, the inorganic filler may aggregate during surface treatment. In this specification, the M value represents the hydrophobicity of the particle powder surface and is the volume percentage of methanol at which the particle powder begins to wet the mixed liquid when the mixing ratio of water and methanol is changed (when the methanol ratio is increased). Specifically, 50 mL of water is placed in a 300 mL beaker, 0.2 g of inorganic filler is added, and methanol is added dropwise from a burette while stirring with a magnetic stirrer at 23°C until the inorganic filler is suspended. The time when the inorganic filler is suspended in the solution is set as the end point, and the M value can be determined as the volume percentage of methanol in the liquid mixture in the beaker at the end point. Since the measured value varies depending on the amount of inorganic filler and the temperature, the value under the above measurement conditions is used herein as the M value.

[0021] The preferred lower limit of the content of the inorganic filler relative to 100 parts by mass of the curable resin described below is 6 parts by mass. When the content of the inorganic filler is 6 parts by mass or more, the resulting sealant for liquid crystal display elements will have better adhesion and moisture permeation prevention properties. The more preferred lower limit of the content of the inorganic filler is 9 parts by mass. From the viewpoint of further improving transparency, the preferred upper limit of the content of the inorganic filler is 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass.

[0022] The sealant for liquid crystal display elements of the present invention may contain an organic filler to the extent that the object of the present invention is not impaired. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and (meth)acrylic polymer fine particles. In this specification, the term "(meth)acrylic" refers to acrylic or methacrylic.

[0023] The sealant for a liquid crystal display element of the present invention contains a curable resin, which preferably contains at least one selected from the group consisting of a (meth)acrylic compound and an epoxy compound, and more preferably contains a (meth)acrylic compound and an epoxy compound.

[0024] Examples of the (meth)acrylic compound include (meth)acrylic acid ester compounds, epoxy (meth)acrylates, and urethane (meth)acrylates. Of these, epoxy (meth)acrylates are preferred. From the viewpoint of reactivity, the (meth)acrylic compound preferably has two or more (meth)acryloyl groups in one molecule. In this specification, the term "(meth)acrylate" refers to an 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.

[0025] 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 isononyl (meth)acrylate. Myristyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, bicyclopentenyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (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-tetrafluoropropyl Examples of the acrylates include 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, and glycidyl (meth)acrylate.

[0026] 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, and propylene glycol di(meth)acrylate. Examples of suitable 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.

[0027] 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.

[0028] Examples of the epoxy (meth)acrylate include those obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a basic catalyst according to a conventional method.

[0029] 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 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.

[0030] Commercially available examples of the bisphenol A epoxy compounds include jER828EL and jER1004 (both manufactured by Mitsubishi Chemical Corporation), and EPICLON EXA-850CRP (manufactured by DIC Corporation). Commercially available examples of the bisphenol F epoxy compounds include jER806 and jER4004 (both manufactured by Mitsubishi Chemical Corporation). Commercially available examples of the bisphenol S epoxy compounds include EPICLON EXA1514 (manufactured by DIC Corporation). Commercially available examples of the 2,2'-diallyl bisphenol A epoxy compounds include RE-810NM (manufactured by Nippon Kayaku Co., Ltd.). Commercially available examples of the hydrogenated bisphenol epoxy compounds include EPICLON EXA7015 (manufactured by DIC Corporation). Commercially available examples of the propylene oxide-added bisphenol A epoxy compounds include EP-4000S (manufactured by ADEKA Corporation). Commercially available examples of the resorcinol epoxy compounds include EX-201 (manufactured by Nagase ChemteX Corporation). Commercially available examples of the biphenyl epoxy compounds include jER YX-4000H (manufactured by Mitsubishi Chemical Corporation). Commercially available examples of the sulfide epoxy compounds include YSLV-50TE (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Commercially available examples of the diphenyl ether epoxy compounds include YSLV-80DE (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Commercially available examples of the dicyclopentadiene epoxy compounds include EP-4088S (manufactured by ADEKA Corporation). Commercially available examples of the naphthalene epoxy compounds include EPICLON HP4032 and EPICLON EXA-4700 (both manufactured by DIC Corporation), etc. Commercially available examples of the phenol novolac epoxy compounds include EPICLON N-770 (manufactured by DIC Corporation), etc.Commercially available ortho-cresol novolac epoxy compounds include, for example, EPICLON N-670-EXP-S (manufactured by DIC Corporation). Commercially available dicyclopentadiene novolac epoxy compounds include, for example, EPICLON HP7200 (manufactured by DIC Corporation). Commercially available biphenyl novolac epoxy compounds include, for example, NC-3000P (manufactured by Nippon Kayaku Co., Ltd.). Commercially available naphthalene phenol novolac epoxy compounds include, for example, ESN-165S (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Commercially available glycidylamine epoxy compounds include, for example, jER630 (manufactured by Mitsubishi Chemical Corporation), EPICLON 430 (manufactured by DIC Corporation), and TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc.). Commercially available examples of the alkyl polyol epoxy compounds include ZX-1542 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), EPICLON 726 (manufactured by DIC Corporation), Epolite 80MFA (manufactured by Kyoeisha Chemical Co., Ltd.), and Denacol EX-611 (manufactured by Nagase ChemteX Corporation). Commercially available examples of the rubber-modified epoxy compounds include YR-450 and YR-207 (both manufactured by Nippon Steel Chemical & Material Co., Ltd.), and Epolead PB (manufactured by Daicel Corporation). Commercially available examples of the glycidyl ester compounds include Denacol EX-147 (manufactured by Nagase ChemteX Corporation). Other commercially available epoxy compounds include, for example, YDC-1312, YSLV-80XY, and YSLV-90CR (all manufactured by Nippon Steel Chemical & Material Co., Ltd.), XAC4151 (manufactured by Asahi Kasei Corporation), jER1031 and jER1032 (both manufactured by Mitsubishi Chemical Corporation), EXA-7120 (manufactured by DIC Corporation), and TEPIC (manufactured by Nissan Chemical Industries, Ltd.).

[0031] 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 EBECRYL 860, EBECRYL 3200, EBECRYL 3201, EBECRYL 3412, EBECRYL 3600, EBECRYL 3700, EBECRYL 3701, EBECRYL 3702, EBECRYL 3703, EBECRYL 3708, EBECRYL 3800, EBECRYL 6040, and EBECRYL RDX 63182. 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, Epoxy Ester 400EA, etc. Examples of the epoxy (meth)acrylates manufactured by Nagase ChemteX Corporation include Denacol Acrylate DA-141, Denacol Acrylate DA-314, Denacol Acrylate DA-911, etc.

[0032] The urethane (meth)acrylate can be obtained, for example, by reacting a polyfunctional isocyanate compound with a (meth)acrylic acid derivative having a hydroxyl group in the presence of a catalytic amount of a tin compound.

[0033] Examples of the polyfunctional isocyanate compound 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.

[0034] Furthermore, the polyfunctional isocyanate compound may be a chain-extended polyfunctional isocyanate compound obtained by reacting a polyol with an excess of the polyfunctional isocyanate compound. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0035] Examples of the (meth)acrylic acid derivatives having a hydroxyl group include hydroxyalkyl mono(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 mono(meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of the dihydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of the trihydric alcohols include trimethylolethane, trimethylolpropane, and glycerin. Examples of the epoxy (meth)acrylates include bisphenol A-type epoxy acrylate.

[0036] Among the above 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 Industrial Co., Ltd., urethane (meth)acrylate manufactured by Shin-Nakamura Chemical Co., Ltd., and urethane (meth)acrylate manufactured by Kyoeisha Chemical Co., Ltd. Examples of the above urethane (meth)acrylate 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 Co., Ltd. include EBECRYL210, EBECRYL220, EBECRYL230, EBECRYL270, EBECRYL1290, EBECRYL2220, EBECRYL4827, EBECRYL4842, EBECRYL4858, EBECRYL5129, EBECRYL6700, EBECRYL8402, EBECRYL8803, EBECRYL8804, EBECRYL8807, and EBECRYL9260. Examples of the 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.

[0037] Examples of the epoxy compound include the epoxy compounds that serve as raw materials for synthesizing the above-mentioned epoxy (meth)acrylates, partially (meth)acrylic-modified epoxy compounds, etc. In this specification, the 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 can be obtained, for example, by reacting some of the epoxy groups of an epoxy compound having two or more epoxy groups in one molecule with (meth)acrylic acid.

[0038] When the curable resin contains the (meth)acrylic compound and the epoxy compound, or when the curable resin contains the partially (meth)acrylic-modified epoxy compound, it is preferable that the ratio of (meth)acryloyl groups in the total of (meth)acryloyl groups and epoxy groups in the curable resin is 30 mol % or more and 95 mol % or less. By having the ratio of (meth)acryloyl groups in this range, the occurrence of liquid crystal contamination can be suppressed, and the resulting sealant for liquid crystal display elements can have excellent adhesion.

[0039] The curable resin preferably contains an —OH group, an —NH— group, an —NH ２ Those having a hydrogen-bonding unit such as a group are preferred.

[0040] The curable resins may be used alone or in combination of two or more.

[0041] The sealing agent for liquid crystal display elements of the present invention contains a photopolymerization initiator. Examples of the photopolymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, and thioxanthone compounds. Specific examples of the photopolymerization 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, and 2-methyl-1-(4-methylthiophenyl)- ... -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-(acetoxyimino)-1-(4-(4-(2-hydroxyethoxy)phenylthio)phenyl)propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4-dimethylthioxanthen-9-one, and the like.

[0042] The content of the photopolymerization 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 a photopolymerization initiator in this range, the resulting sealant for liquid crystal display elements has better storage stability and photocurability. The more preferred lower limit of the content of the photopolymerization initiator is 0.1 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0043] The sealant for liquid crystal display elements of the present invention may contain a thermal polymerization initiator. Examples of the thermal polymerization initiator include those composed of an azo compound, an organic peroxide, etc. Among these, a polymeric azo initiator composed of a polymeric azo compound is preferred. The thermal polymerization initiator may be used alone or in combination of two or more. In this specification, the term "polymeric azo compound" refers to a compound having an azo group, generating a radical capable of curing a (meth)acryloyloxy group by heat, and having a number average molecular weight of 300 or more.

[0044] The number-average molecular weight of the polymeric azo compound is preferably 1,000 at its lower limit and 300,000 at its upper limit. By ensuring that the number-average molecular weight of the polymeric azo compound is within this range, the polymeric azo compound can be easily mixed with a curable resin while suppressing liquid crystal contamination. The number-average molecular weight of the polymeric azo compound is more preferably 5,000 at its lower limit and 100,000 at its upper limit, and even more preferably 10,000 at its lower limit and 90,000 at its upper limit.

[0045] Examples of the polymeric azo compounds include those having a structure in which multiple units such as polyalkylene oxide or polydimethylsiloxane are bonded via an azo group. As the polymeric azo compounds having a structure in which multiple units such as polyalkylene oxide are bonded via an azo group, those having a polyethylene oxide structure are preferred. Specific examples of the polymeric azo compounds include polycondensates of 4,4'-azobis(4-cyanopentanoic acid) and polyalkylene glycol, and polycondensates of 4,4'-azobis(4-cyanopentanoic acid) and polydimethylsiloxane having a terminal amino group. Commercially available examples of the polymeric azo compounds include VPE-0201, VPE-0401, VPE-0601, VPS-0501, and VPS-1001 (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Examples of non-polymeric azo compounds include V-65 and V-501 (both manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0046] Examples of the organic peroxide include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, and peroxydicarbonates.

[0047] The content of the thermal polymerization initiator is preferably 0.05 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. When the content of the thermal polymerization initiator is 0.05 parts by mass or more, the sealant for liquid crystal display elements of the present invention has superior thermosetting properties. When the content of the thermal polymerization initiator is 10 parts by mass or less, the sealant for liquid crystal display elements of the present invention has superior low liquid crystal contamination properties and storage stability. The lower limit of the content of the thermal polymerization initiator is more preferably 0.1 parts by mass, and the upper limit is more preferably 5 parts by mass.

[0048] The sealant for liquid crystal display elements of the present invention further contains a heat curing agent. Examples of the heat curing agent include organic acid hydrazides, imidazole derivatives, amine compounds, polyhydric phenol compounds, and acid anhydrides. Among these, organic acid hydrazides and imidazole derivatives are preferably used from the viewpoint of achieving both adhesiveness and moisture permeability. Furthermore, the heat curing agent is preferably liquid at 25°C from the viewpoint of achieving both transparency and moisture permeability, and imidazole derivatives that are liquid at 25°C are more preferably used. The use of a heat curing agent that is liquid at 25°C enables uniform curing and reduces curing unevenness, which is thought to improve the transparency of the resulting cured product of the sealant for liquid crystal display elements.

[0049] Examples of the organic acid hydrazides include sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, and malonic acid dihydrazide. Commercially available organic acid hydrazides include those manufactured by Otsuka Chemical Co., Ltd., those manufactured by Ajinomoto Fine-Techno Co., Ltd., and those manufactured by Japan FineChem Co., Ltd. Examples of the organic acid hydrazides manufactured by Otsuka Chemical Co., Ltd. include SDH and ADH. Examples of the organic acid hydrazides manufactured by Ajinomoto Fine-Techno Co., Ltd. include Amicure VDH, Amicure VDH-J, Amicure UDH, and Amicure UDH-J. Examples of the organic acid hydrazides manufactured by Japan FineChem Co., Ltd. include MDH.

[0050] 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 using the thermosetting agent in this range, the resulting sealant for liquid crystal display elements can have excellent thermosetting properties while maintaining storage stability and coatability. The more preferred upper limit of the content of the thermosetting agent is 30 parts by mass.

[0051] The sealant for liquid crystal display elements of the present invention preferably contains a silane coupling agent. The silane coupling agent mainly serves as an adhesion aid for providing good adhesion between the sealant for liquid crystal display elements and a substrate, etc. Suitable examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-glycidoxypropyltrimethoxysilane.

[0052] The preferred lower limit of the content of the silane coupling agent in 100 parts by mass of the sealant for liquid crystal display elements of the present invention is 0.1 parts by mass, and the preferred upper limit is 10 parts by mass. By having the content of the silane coupling agent in this range, the resulting sealant for liquid crystal display elements will be more excellent in the effect of improving adhesion while suppressing the occurrence of liquid crystal contamination. 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 5 parts by mass.

[0053] The sealant for a liquid crystal display element of the present invention may further contain additives such as a stress relaxation agent, a reactive diluent, a curing accelerator, an antifoaming agent, a leveling agent, and a polymerization inhibitor, if necessary.

[0054] The method for producing the sealant for liquid crystal display elements of the present invention includes, for example, a method of mixing a curable resin, an inorganic filler, and other components such as a photopolymerization initiator using a mixer. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mill.

[0055] Furthermore, by blending conductive fine particles into the sealant for liquid crystal display elements of the present invention, a vertical conductive material can be produced. Examples of the conductive fine particles that can be used include metal balls and resin fine particles with a conductive metal layer formed on their surfaces. Among these, resin fine particles with a conductive metal layer formed on their surfaces are preferred because the excellent elasticity of the resin fine particles allows for conductive connection without damaging transparent substrates, etc.

[0056] A liquid crystal dropping method is preferably used as a method for producing a liquid crystal display element using the sealant for liquid crystal display elements of the present invention, and specific examples include methods having the following steps. First, a step is performed in which the sealant for liquid crystal display elements of the present invention is applied by screen printing, dispenser application, or the like to one of two transparent substrates having electrodes such as ITO thin films to form a frame-shaped seal pattern. Next, a step is performed in which minute droplets of liquid crystal are dropwise applied to the entire frame of the seal pattern, and the other transparent substrate is superimposed under vacuum. Thereafter, a liquid crystal display element can be obtained by a method in which a step of irradiating the seal pattern portion with light such as ultraviolet light to temporarily cure the sealant (photocuring step), and a step of heating the temporarily cured sealant to permanently cure it (thermal curing step).

[0057] According to the present invention, it is possible to provide a sealant for a liquid crystal display element that is excellent in transparency, adhesiveness, and moisture permeation prevention properties.

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] (Synthesis of bisphenol A-type epoxy methacrylate) 173 g of a bisphenol A-type epoxy compound (DIC Corporation, "EPICLON EXA-850CRP") was dissolved in 500 mL of toluene, and 0.1 g of triphenylphosphine was added to this solution to obtain a homogeneous solution. 84 g of methacrylic acid was added dropwise to the resulting solution under reflux and stirring over a period of 2 hours, and the mixture was then further refluxed and stirred for 8 hours. Next, the toluene was removed to obtain bisphenol A-type epoxy methacrylate in which all of the epoxy groups had been modified to methacryloyl groups.

[0060] (Synthesis of flexible backbone-containing bisphenol A epoxy acrylate) 116 parts by mass of 2-hydroxyethyl acrylate and 114 parts by mass of ε-caprolactone were placed in a reaction flask, and 0.3 parts by mass of hydroquinone as a polymerization inhibitor was added. The mixture was heated to 90°C with a mantle heater and stirred for 5 hours. 148 parts by mass of phthalic anhydride was added to the obtained product and stirred for an additional 5 hours. Subsequently, 170 parts by mass of bisphenol A diglycidyl ether was added, and the mixture was stirred at 90°C for 5 hours to obtain a flexible backbone-containing bisphenol A epoxy acrylate.

[0061] (Synthesis of Partially Acrylic-Modified Bisphenol E Epoxy Compound) 173 g of a bisphenol E epoxy compound (Mitsui Chemicals, Inc., "R-710") was dissolved in 500 mL of toluene, and 0.1 g of triphenylphosphine was added to this solution to form a homogeneous solution. 52.5 g of acrylic acid was added dropwise to the resulting solution over 2 hours under reflux and stirring, followed by an additional 6 hours of reflux and stirring. Next, the toluene was removed to obtain a partially acrylic-modified bisphenol E epoxy compound in which 75 mol % of the epoxy groups had reacted with acrylic acid. The degree of modification of the epoxy groups was measured by dissolving the resulting compound in a hydrochloric acid-dioxane solution and then titrating the amount of hydrochloric acid consumed by the epoxy groups with KOH.

[0062] (Synthesis of Silica-Titania Composite Oxide A) 9.0 g of water and 208 g of tetraethyl silicate were dissolved in 1.2 L of methanol. The resulting solution was hydrolyzed with stirring at room temperature for approximately 2 hours, and then added with stirring to a solution of 90.0 g of tetrabutyl titanate dissolved in 1.0 L of isopropanol to prepare a mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate. Next, a 10 L glass reactor equipped with a stirrer was filled with 2.5 L of methanol, and 500 g of aqueous ammonia (concentration 25% by mass) was added to prepare an ammoniacal methanol solution. The previously prepared mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate was added to the resulting ammoniacal methanol solution over approximately 2 hours while maintaining the temperature of the reaction vessel at 20°C. The reaction solution turned milky white within a few minutes of the start of addition. After the addition was completed, stirring was continued for another hour, and the solution was removed from the milky white reaction liquid using an evaporator. The solution was then dried under reduced pressure at 80°C to obtain a milky white powder (silica-titania composite oxide A). The refractive index of the obtained silica-titania composite oxide A at 25°C was measured by the immersion method using an Abbe refractometer (manufactured by ERMA, "Universal Abbe Refractometer ER-7MW") and an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, "UV-3101PC"), and the refractive index was found to be 1.60. The average primary particle diameter of the obtained silica-titania composite oxide A was measured using a SEM-EDX measurement device (manufactured by Hitachi High-Technologies Corporation, "S-4800") and was found to be 0.3 µm. Furthermore, for the obtained silica-titania composite oxide A, 50 mL of water was placed in a 300 mL beaker, 0.2 g of inorganic filler was added, and methanol was added dropwise from a burette while stirring with a magnetic stirrer at 23° C. until the inorganic filler was suspended. The M value, measured as the volume percentage of methanol in the liquid mixture in the beaker at the end point, was 0 when the inorganic filler was suspended in the solution.

[0063] (Synthesis of Silica-Titania Composite Oxide B) 7.2 g of water and 208 g of tetraethyl silicate were dissolved in 1.2 L of methanol. The resulting solution was hydrolyzed with stirring at room temperature for approximately 2 hours, and then added to a solution of 72.0 g of tetrabutyl titanate dissolved in 1.0 L of isopropanol with stirring to prepare a mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate. Next, a 10 L glass reactor equipped with a stirrer was filled with 2.5 L of methanol, and 500 g of aqueous ammonia (concentration 25% by mass) was added to prepare an ammoniacal methanol solution. The previously prepared mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate was added to the resulting ammoniacal methanol solution over approximately 2 hours while maintaining the temperature of the reaction vessel at 20°C. The reaction solution turned milky white within a few minutes of the start of addition. After the addition was completed, stirring was continued for another hour, and the solution was removed from the milky white reaction liquid using an evaporator. The mixture was then dried under reduced pressure at 80°C to obtain a milky white powder (silica-titania composite oxide B). The refractive index of the obtained silica-titania composite oxide B was measured at 25°C by the immersion method using an Abbe refractometer (ERMA, "Universal Abbe Refractometer ER-7MW") and an ultraviolet-visible spectrophotometer (Shimadzu Corporation, "UV-3101PC"), and the refractive index was found to be 1.56. The average primary particle diameter of the obtained silica-titania composite oxide B was measured using a SEM-EDX measurement device (Hitachi High-Technologies Corporation, "S-4800") and was found to be 0.3 μm. Furthermore, the M value of the obtained silica-titania composite oxide B, measured using the same method as for the silica-titania composite oxide A, was found to be 0.

[0064] (Synthesis of Silica-Titania Composite Oxide C) 5.4 g of water and 208 g of tetraethyl silicate were dissolved in 1.2 L of methanol. The resulting solution was hydrolyzed with stirring at room temperature for approximately 2 hours, and then added with stirring to a solution of 36.0 g of tetrabutyl titanate dissolved in 1.0 L of isopropanol to prepare a mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate. Next, a 10 L glass reactor equipped with a stirrer was filled with 2.5 L of methanol, and 500 g of aqueous ammonia (concentration 25% by mass) was added to prepare an ammoniacal methanol solution. The previously prepared mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate was added to the resulting ammoniacal methanol solution over approximately 2 hours while maintaining the temperature of the reaction vessel at 20°C. The reaction solution turned milky white within a few minutes of the start of addition. After the addition was completed, stirring was continued for another hour, and the solution was removed from the milky white reaction liquid using an evaporator. The resulting mixture was then dried under reduced pressure at 80°C to obtain a milky white powder (silica-titania composite oxide C). The refractive index of the resulting silica-titania composite oxide C was measured at 25°C by the immersion method using an Abbe refractometer (ERMA, "Universal Abbe Refractometer ER-7MW") and an ultraviolet-visible spectrophotometer (Shimadzu Corporation, "UV-3101PC"), resulting in a refractive index of 1.50 relative to the sodium D line. The average primary particle diameter of the resulting silica-titania composite oxide C was measured using a SEM-EDX measurement device (Hitachi High-Technologies Corporation, "S-4800") and found to be 0.3 μm. Furthermore, the M value of the resulting silica-titania composite oxide C, measured using the same method as for the silica-titania composite oxide A, was found to be 0.

[0065] (Synthesis of Surface-Treated Silica-Titania Composite Oxide D) 7.2 g of water and 208 g of tetraethyl silicate were dissolved in 1.2 L of methanol. The resulting solution was hydrolyzed with stirring at room temperature for approximately 2 hours, and then added to a solution of 72.0 g of tetrabutyl titanate dissolved in 1.0 L of isopropanol with stirring to prepare a mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate. Next, a 10 L glass reactor equipped with a stirrer was filled with 2.5 L of methanol, and 500 g of aqueous ammonia (concentration 25% by mass) was added to prepare an ammoniacal methanol solution. The previously prepared mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate was added to the resulting ammoniacal methanol solution over approximately 2 hours while maintaining the temperature of the reaction vessel at 20°C. The reaction solution turned milky white within a few minutes of the start of addition. After the addition was completed, stirring was continued for another hour, and the solution was removed from the milky white reaction liquid using an evaporator. This was followed by drying under reduced pressure at 80°C to obtain a milky white powder (silica-titania composite oxide). 10 parts by mass of the obtained silica-titania composite oxide was dispersed in 100 parts by mass of an ethanol solution in which 5 parts by mass of methyltriethoxysilane had been dissolved, and the mixture was allowed to react for 1 hour under reflux of ethanol to obtain a surface-treated silica-titania composite oxide D having methyl groups as hydrophobic groups on its surface. The refractive index of the obtained surface-treated silica-titania composite oxide D was measured at 25°C by the immersion method using an Abbe refractometer (manufactured by ERMA, "Universal Abbe Refractometer ER-7MW") and an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, "UV-3101PC"), and the refractive index was found to be 1.56. The average primary particle diameter of the obtained surface-treated silica-titania composite oxide D was measured using a SEM-EDX measuring device ("S-4800" manufactured by Hitachi High-Technologies Corporation) and was found to be 0.3 μm. Furthermore, the M value of the obtained surface-treated silica-titania composite oxide D, measured in the same manner as for the above silica-titania composite oxide A, was found to be 31.

[0066] (Examples 1 to 10 and Comparative Examples 1 to 4) Each material was mixed using a planetary mixer according to the blending ratios shown in Table 1, and then further mixed using a three-roll mill to prepare sealants for liquid crystal display elements in Examples 1 to 10 and Comparative Examples 1 to 4. Awatori Mixer (manufactured by Thinky Corporation) was used as the planetary mixer.

[0067] (Haze Measurement) Each of the obtained sealants for liquid crystal display elements was applied onto a glass substrate, and then the applied sealant was irradiated with UV light at a wavelength of 365 nm and an illuminance of 100 mW / cm using a UV irradiator. ２ The cured product was irradiated with ultraviolet light of 1000 nm through a 340 nm cut filter for 30 seconds, followed by heating at 120°C for 60 minutes, to obtain a cured product with a thickness of 100 μm. The haze of the resulting cured product was measured using a spectrometer. The UV irradiator used was an MB1500T-3 (manufactured by Sen Special Light Sources Co., Ltd.), and the spectrometer used was an AUTOMATIC HAZE METER MODEL TC-III DPK (manufactured by Tokyo Denshoku Co., Ltd.). The results are shown in Table 1.

[0068] (Measurement of Moisture Permeability) Each of the obtained sealants for liquid crystal display elements was applied onto a smooth release film using a coater. Then, the applied sealant was irradiated with UV light at a wavelength of 365 nm and an illuminance of 100 mW / cm using a UV irradiator. ２ The sample was irradiated with ultraviolet light of 1000 nm through a 340 nm cut filter for 30 seconds, followed by heating at 120°C for 60 minutes to obtain a cured product (thickness: 300 μm). The UV irradiator used was an MB1500T-3 (manufactured by Sen Special Light Sources Co., Ltd.). A moisture permeability test cup was prepared according to JIS Z 0208, moisture permeability test method for moisture-proof packaging materials (cup method), and the cured product was attached to a cup. The cup was then placed in a constant temperature and humidity oven at 80°C and 90% RH to measure the moisture permeability. The results are shown in Table 1.

[0069] (Measurement of adhesive strength to glass) Each of the obtained sealants for liquid crystal display elements was applied to one of two glass substrates in dots so that the diameter of the dots when the substrates were bonded together was 3 mm. The glass substrate with the dotted sealant and the other glass substrate were bonded together in a cross shape via the sealant. Thereafter, the glass substrate was irradiated with UV light at a wavelength of 365 nm and an illuminance of 100 mW / cm using a UV irradiator. ２The sealant was cured by irradiating it with ultraviolet light through a 340 nm cut filter for 30 seconds, followed by heating at 120°C for 60 minutes to obtain a test specimen. The UV irradiator used was an MB1500T-3 (manufactured by Sen Special Light Sources Co., Ltd.). The adhesive strength to glass was measured by performing a tensile test on the obtained test specimen at 5 mm / sec using chucks arranged above and below the specimen in an environment of 25°C. The results are shown in Table 1.

[0070] (Measurement of Adhesion Strength to Alignment Film) An imide resin (manufactured by Nissan Chemical Industries, Ltd.) was spin-coated onto the same glass substrate as used in the above "(Measurement of Adhesion Strength to Glass)" and pre-baked at 80°C, followed by baking at 230°C to produce a substrate having an alignment film. Using the obtained substrate, a test piece was produced in the same manner as in the above "(Measurement of Adhesion Strength to Glass)". The adhesion strength to the alignment film was measured by performing a tensile test on the obtained test piece at 25°C using chucks arranged above and below at 5 mm / sec. The results are shown in Table 1.

[0071] (Measurement of refractive index of cured product of curable resin) 100 parts by mass of the same curable resin as that contained in each obtained sealant for liquid crystal display elements was mixed with 1.3 parts by mass of 1-(4-(phenylthio)phenyl)-1,2-octanedione 2-(O-benzoyloxime) as a photopolymerization initiator and 4 parts by mass of malonic acid dihydrazide as a heat curing agent to obtain a curable resin composition. The obtained curable resin composition was irradiated with a UV irradiator at a wavelength of 365 nm and an illuminance of 100 mW / cm. ２ for 30 seconds through a 340 nm cut filter, followed by heating at 120°C for 60 minutes to obtain a cured product. The UV irradiator used was an MB1500T-3 (manufactured by Sen Special Light Sources Co., Ltd.). The refractive index of the obtained cured product at the sodium D line was measured at 25°C using an Abbe refractometer (manufactured by ERMA, "Universal Abbe Refractometer ER-7MW"). The results are shown in Table 1.

[0072] <Evaluation> The sealants for liquid crystal display elements obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 1.

[0073] (Transparency) Transparency was evaluated by assigning a "◎" when the haze measured in the above "(Haze Measurement)" was 40% or less, a "◯" when it was more than 40% and 60% or less, and an "×" when it was more than 60%.

[0074] (Adhesion) Adhesion to glass was evaluated by assigning a "◎" when the adhesive strength measured in the above "(Measurement of adhesive strength to glass)" was 2.3 kgf / cm or more, a "◯" when it was 2.0 kgf / cm or more and less than 2.3 kgf / cm, and an "×" when it was less than 2.0 kgf / cm. Adhesion to alignment film was evaluated by assigning a "◎" when the adhesive strength measured in the above "(Measurement of adhesive strength to alignment film)" was 1.5 kgf / cm or more, a "◯" when it was 1.0 kgf / cm or more and less than 1.5 kgf / cm, and an "×" when it was less than 1.0 kgf / cm.

[0075] (Moisture permeability prevention) The moisture permeability measured in the above "(Measurement of moisture permeability)" is 80 g / m ２ If it was less than 24 hours, it was marked as "◎", and if it was less than 80 g / m ２ ・Over 24 hours 85g / m ２ If it was 24 hours or less, it was marked as "○", and if it was 85 g / m ２ ・Over 24 hours 90g / m ２ If it was 24 hours or less, it was marked "△", and if it was 90 g / m ２ When the time exceeded 24 hours, the moisture permeability was evaluated as "X".

[0076]

[0077] According to the present invention, it is possible to provide a sealant for a liquid crystal display element that is excellent in transparency, adhesiveness, and moisture permeation prevention properties.

Claims

1. A sealant for a liquid crystal display element, comprising a curable resin, an inorganic filler, a photopolymerization initiator, and a heat curing agent, The inorganic filler is a silica-titania composite oxide, The sealant for liquid crystal display elements has a haze of 60% or less when cured with a thickness of 100 μm, and a moisture permeability of 90 g / m2 or less when cured with a thickness of 300 μm under an environment of 80° C. and 90% RH, as measured in accordance with JIS Z 0208. ２ A sealant for liquid crystal display devices, characterized in that the durability is 24 hours or less.

2. 2. The sealant for liquid crystal display elements according to claim 1, wherein the adhesive strength of the cured product of the sealant for liquid crystal display elements to glass at 25° C. is 2.0 kgf / cm or more.

3. 3. The sealant for liquid crystal display elements according to claim 1, wherein the inorganic filler has a refractive index of 1.50 or more and 1.60 or less, and the difference in refractive index between the cured product of the curable resin and the inorganic filler is 0.08 or less.

4. 3. The sealant for a liquid crystal display element according to claim 1, wherein the inorganic filler has an M value of 20 or more.

5. 3. The sealant for liquid crystal display elements according to claim 1, wherein the heat curing agent contains an imidazole derivative which is liquid at 25[deg.] C.