Sealant for liquid crystal display devices

Abstract

The purpose of the present invention is to provide a sealing agent that is for a liquid crystal display element, and that has excellent adhesiveness and is capable of inhibiting a substrate from coming off a large-size mother glass even when the sealing agent is applied to the mother glass at a high density. The present invention is a liquid crystal display element sealing agent that comprises a curable resin and an organic filler, and that has photocuring properties and thermosetting properties. When the liquid crystal display element sealing agent in an uncured state has undergone a photocuring step for irradiating the liquid crystal display element sealing agent with ultraviolet light having a wavelength of 300-500 nm and an illuminance of 100 mW / cm2 for 30 seconds using a high-pressure mercury lamp, the shrinkage ratio of the liquid crystal display element sealing agent after the photocuring step with respect to the uncured liquid crystal display element sealing agent is at most 3.5% at 25°C. When, after the photocuring step, the liquid crystal display element sealing agent is heated to 130°C at a temperature increase rate of 10°C / min, and has further undergone a thermal-curing step at 130°C for 60 minutes, the maximum expansion ratio of the liquid crystal display element sealing agent during the thermal-curing step with respect to the uncured liquid crystal display element sealing agent is not less than 1.5% but less than 4%. When the thermal-curing step is performed after the photocuring step, the shrinkage ratio of the liquid crystal display element sealing agent during a period of time from the time when the liquid crystal display element sealing agent exhibits the maximum expansion ratio during the thermal-curing step until the end of the thermal-curing step is at least 0.1%.

Description

[Technical field]

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

[0002] In recent years, as a method for manufacturing liquid crystal display elements such as liquid crystal display cells, a method called a dropping method using a curable resin composition as a sealant as disclosed in Patent Documents 1 and 2 has been used 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 substrates with electrodes, forming a frame-shaped seal pattern. Next, while the sealant is still in an uncured state, tiny droplets of liquid crystal are dropped into the seal frame of the substrate, and the other substrate is placed on top of it in a vacuum, and the sealant is cured by light irradiation or heat, producing a liquid crystal display element. Currently, this dropping method is the mainstream method for manufacturing liquid crystal display elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-133794 A [Patent Document 2] WO 02 / 092718 Summary of the Invention [Problem to be solved by the invention]

[0004] Usually, liquid crystal display elements are manufactured by forming a plurality of cells on a mother glass at once, and then dividing each cell. In recent years, the size of mother glass has been increasing, and a sealant is densely applied to one sheet of mother glass. As a result, the substrate is warped, and even if a sealant with excellent adhesiveness is used, the sealant cannot follow the warp, and the substrate is easily peeled off. In particular, when the sealant is hardened in a photo-curing process and a heat-curing process after the photo-curing process, the substrate may be peeled off due to stress caused by distortion between the substrates after the photo-curing process, transportation of the cell into a heating furnace in the heat-curing process, vibration in the heating furnace, etc. In addition, liquid crystal display elements are required to have high reliability in driving under high temperature and high humidity environments, and a sealant that has excellent adhesiveness even under high temperature and high humidity environments and has a performance with less distortion and defects due to changes in the external environment is required to meet this requirement. An object of the present invention is to provide a sealant for liquid crystal display elements which has excellent adhesiveness and can prevent peeling of the substrate even when applied at high density to a large mother glass. [Means for solving the problem]

[0005] Disclosure 1 relates to a sealant for liquid crystal display elements, which contains a curable resin and an organic filler and has photocurability and thermosetting properties, and which is characterized in that the uncured sealant for liquid crystal display elements is irradiated with a high-pressure mercury lamp at a wavelength of 300 to 500 nm and an illuminance of 100 mW / cm 2when a photo-curing step is performed in which the sealant for liquid crystal display elements is irradiated with ultraviolet light of 100 nm for 30 seconds, the shrinkage rate at 25°C of the sealant for liquid crystal display elements after the photo-curing step is 3.5% or less compared to the uncured sealant for liquid crystal display elements; when a heat-curing step is performed in which the sealant for liquid crystal display elements is heated to 130°C at a heating rate of 10°C / min after the photo-curing step and further heated at 130°C for 60 minutes, the maximum expansion rate of the sealant for liquid crystal display elements during the heat-curing step is 1.5% or more and less than 4% compared to the uncured sealant for liquid crystal display elements; and when the heat-curing step is performed after the photo-curing step, the shrinkage rate of the sealant for liquid crystal display elements during the period from when the sealant for liquid crystal display elements shows its maximum expansion rate during the heat-curing step to the end of the heat-curing step is 0.1% or more. The present disclosure 2 relates to a sealant for a liquid crystal display element according to the present disclosure 1, wherein the curable resin contains an epoxy compound and a (meth)acrylic compound. The present disclosure 3 is the sealant for a liquid crystal display element according to the present disclosure 2, wherein the total content of the epoxy compound and the organic filler is ⅓ or more of the total content of the curable resin. The present disclosure 4 is the sealant for a liquid crystal display element according to the present disclosure 1, 2 or 3, further comprising an inorganic filler, wherein the content of the organic filler is equal to or greater than the content of the inorganic filler. The present disclosure 5 is the sealant for a liquid crystal display element according to the present disclosure 1, 2, 3 or 4, further comprising a thermal radical polymerization initiator. The present disclosure 6 is a sealant for liquid crystal display elements according to the present disclosure 1, 2, 3, 4 or 5, in which, when the heat curing step is carried out after the photocuring step, the glass transition temperature of the cured product after the heat curing step is 80°C or higher and 110°C or lower. The present invention will be described in detail below.

[0006] The inventors considered that the shrinkage rate of the sealant in the photo-curing process, the maximum expansion rate of the sealant in the heat-curing process after the photo-curing process, and the shrinkage rate of the sealant in the heat-curing process greatly affect the conformability to the substrate. The inventors then discovered that by adjusting these values ​​to specific ranges, the sealant has excellent adhesion and can suppress peeling of the substrate even when it is applied at high density to a large mother glass, and thus completed the present invention.

[0007] The sealant for a liquid crystal display element of the present invention has photocuring properties and heat curing properties. The sealant for liquid crystal display elements of the present invention is irradiated with the uncured sealant for liquid crystal display elements at a wavelength of 300 to 500 nm and an illuminance of 100 mW / cm by a high-pressure mercury lamp. 2 when a photocuring step is performed in which the sealant for liquid crystal display elements is irradiated with ultraviolet light of 100 nm for 30 seconds, the shrinkage rate at 25°C of the sealant for liquid crystal display elements after the photocuring step relative to the uncured sealant for liquid crystal display elements (hereinafter also referred to as the "shrinkage rate in the photocuring step") is 3.5% or less; when a heat curing step is performed in which the sealant for liquid crystal display elements is heated to 130°C at a temperature increase rate of 10°C / min after the photocuring step and further heated at 130°C for 60 minutes, the maximum expansion rate of the sealant for liquid crystal display elements during the heat curing step relative to the uncured sealant for liquid crystal display elements (hereinafter also referred to as the "maximum expansion rate in the heat curing step") is 1.5% or more and less than 4%; and when the heat curing step is performed after the photocuring step, the shrinkage rate of the sealant for liquid crystal display elements during the period from when the sealant for liquid crystal display elements showed the maximum expansion rate during the heat curing step to the end of the heat curing step (hereinafter also referred to as the "shrinkage rate in the heat curing step") is 0.1% or more. Since the shrinkage rate in the photocuring step is 3.5% or less, the maximum expansion rate in the heat curing step is 1.5% or more and less than 4%, and the shrinkage rate in the heat curing step is 0.1% or more, the sealant for liquid crystal display elements of the present invention has excellent adhesion and can suppress peeling of the substrate even when applied at high density to a large mother glass. The upper limit of the shrinkage rate in the photocuring step is preferably 2.7%, more preferably 2.2%. The lower the shrinkage rate in the photocuring step, the better, but the substantial lower limit is 1.0%. The lower limit of the maximum expansion rate during the heat curing step is preferably 2.0%, and more preferably 3.0%. The lower limit of the shrinkage rate in the heat curing step is preferably 0.5%, and the upper limit of the shrinkage rate in the heat curing step is preferably 2.5%, and more preferably 1.5%. The shrinkage rate in the photocuring step, the maximum expansion rate in the heat curing step, and the shrinkage rate in the heat curing step can be measured using a resin curing shrinkage measuring device in accordance with JIS K 6941. As the resin curing shrinkage measuring device, Custron (manufactured by Acroedge Co., Ltd.) can be used. Fig. 1 shows a graph illustrating an example of the relationship between each process and the shrinkage or expansion rate in a sealant for liquid crystal display elements. In Fig. 1, it can be seen that shrinkage progresses from the start of the light irradiation process, and the volume reduction rate increases by 1.8% after the light curing process, i.e., the shrinkage rate in the light curing process is 1.8%. It can also be seen that expansion progresses when the heat curing process starts, and the volume reduction rate drops to -3.1%, i.e., the maximum expansion rate during the heat curing process is 3.1%. Thereafter, shrinkage progresses, and in the period from the time when the maximum expansion rate is reached to the end of the heat curing process, the volume reduction rate increases by 1.2%, i.e., the shrinkage rate in the heat curing process is 1.2%.

[0008] When the heat curing step is carried out after the photocuring step, the sealant for liquid crystal display elements of the present invention has a glass transition temperature of a cured product after the heat curing step of preferably 80° C. at the lower limit and 110° C. at the upper limit. When the glass transition temperature of the cured product is 80° C. or higher, the liquid crystal display element obtained by using the sealant for liquid crystal display elements of the present invention has better reliability. When the glass transition temperature of the cured product is 110° C. or lower, the sealant for liquid crystal display elements of the present invention has better adhesion. The more preferred lower limit and the more preferred upper limit of the glass transition temperature of the cured product is 90° C. and 100° C., respectively. The glass transition temperature of the cured product can be determined as the temperature at which the loss tangent (tan δ) is maximized when dynamic viscoelasticity is measured at −80 to 200° C. and 10 Hz using a dynamic viscoelasticity measuring device.

[0009] The curable resin preferably contains an epoxy compound and a (meth)acrylic compound. By using the epoxy compound and the (meth)acrylic compound in combination with a photoradical polymerization initiator, a thermal radical polymerization initiator, or a heat curing agent described later, the resulting sealant for liquid crystal display elements can be excellent in photocurability and heat curability. In this specification, the term "(meth)acrylic" means acrylic or methacrylic.

[0010] Examples of the epoxy compound 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, ortho-cresol novolac type epoxy compounds, dicyclopentadiene novolac type epoxy compounds, biphenyl novolac type epoxy compounds, naphthalene phenol novolac type epoxy compounds, glycidyl amine type epoxy compounds, alkyl polyol type epoxy compounds, rubber-modified epoxy compounds, and glycidyl ester compounds.

[0011] Among the above bisphenol A type epoxy compounds, commercially available ones include, for example, jER828EL, jER1004 (both manufactured by Mitsubishi Chemical Corporation), EPICLON EXA-850CRP (manufactured by DIC Corporation), and the like. Among the above bisphenol F type epoxy compounds, commercially available ones include, for example, jER806, jER4004 (both manufactured by Mitsubishi Chemical Corporation), EPICLON EXA-830CRP (manufactured by DIC Corporation), and the like. Among the above bisphenol E type epoxy compounds, a commercially available example is Epomic R710 (manufactured by Mitsui Chemicals, Inc.). Among the above bisphenol S type epoxy compounds, commercially available ones include, for example, EPICLON EXA-1514 (manufactured by DIC Corporation). Among the above 2,2'-diallylbisphenol A type epoxy compounds, a commercially available example is RE-810NM (manufactured by Nippon Kayaku Co., Ltd.). Among the above hydrogenated bisphenol type epoxy compounds, commercially available ones include, for example, EPICLON EXA-7015 (manufactured by DIC Corporation). Among the above propylene oxide-added bisphenol A type epoxy compounds, commercially available ones include, for example, EP-4000S (manufactured by ADEKA Corporation). Among the above resorcinol type epoxy compounds, a commercially available example is EX-201 (manufactured by Nagase ChemteX Corporation). Among the biphenyl type epoxy compounds, examples of commercially available compounds include jER YX-4000H (manufactured by Mitsubishi Chemical Corporation). Among the above sulfide type epoxy compounds, a commercially available example is YSLV-50TE (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Among the diphenyl ether type epoxy compounds, a commercially available example is YSLV-80DE (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Among the above dicyclopentadiene type epoxy compounds, commercially available ones include, for example, EP-4088S (manufactured by ADEKA Corporation). Among the above naphthalene type epoxy compounds, commercially available ones include, for example, EPICLON HP-4032 and EPICLON EXA-4700 (both manufactured by DIC Corporation). Among the above phenol novolac type epoxy compounds, a commercially available example is EPICLON N-770 (manufactured by DIC Corporation). Among the above ortho-cresol novolac type epoxy compounds, a commercially available example is EPICLON N-670-EXP-S (manufactured by DIC Corporation). Among the above dicyclopentadiene novolac type epoxy compounds, a commercially available example is EPICLON HP-7200 (manufactured by DIC Corporation). Among the biphenyl novolac type epoxy compounds, a commercially available example is NC-3000P (manufactured by Nippon Kayaku Co., Ltd.). Among the above naphthalenephenol novolac type epoxy compounds, a commercially available example is ESN-165S (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Among the above glycidylamine type epoxy compounds, commercially available ones include, for example, jER630 (manufactured by Mitsubishi Chemical Corporation), EPICLON430 (manufactured by DIC Corporation), TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc.), and the like. Commercially available examples of the alkyl polyol type epoxy compounds include ZX-1542 (manufactured by Nippon Steel Chemical & Materials 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). Among the above rubber-modified epoxy compounds, commercially available ones include, for example, YR-450, YR-207 (both manufactured by Nippon Steel Chemical & Material Co., Ltd.), Epolead PB (manufactured by Daicel Corporation), and the like. Among the above glycidyl ester compounds, commercially available ones include, for example, Denacol EX-147 (manufactured by Nagase Chemtex Corporation). Other commercially available epoxy compounds include, for example, YDC-1312, YSLV-80XY, YSLV-90CR (all manufactured by Nippon Steel Chemical & Material Co., Ltd.), XAC4151 (manufactured by Asahi Kasei Corporation), jER1031, jER1032 (all manufactured by Mitsubishi Chemical Corporation), EXA-7120 (manufactured by DIC Corporation), and TEPIC (manufactured by Nissan Chemical Industries, Ltd.).

[0012] As the epoxy compound, a partially (meth)acrylic modified epoxy compound can also be suitably used. In this specification, the partially (meth)acrylic modified epoxy compound means a compound having one or more epoxy groups and one or more (meth)acryloyl groups in one molecule, which can be obtained by reacting a part of an epoxy group of an epoxy compound having two or more epoxy groups with (meth)acrylic acid. That is, the partially (meth)acrylic modified epoxy compound has a (meth)acryloyl group, but is treated as the epoxy compound. In this specification, the term "(meth)acryloyl" means acryloyl or methacryloyl.

[0013] Among the partially (meth)acrylic modified epoxy compounds, commercially available ones include, for example, UVACURE1561 and KRM8287 (both manufactured by Daicel-Allnex Corporation).

[0014] Examples of the (meth)acrylic compound include (meth)acrylic acid ester compounds, epoxy (meth)acrylates, and urethane (meth)acrylates. Among these, epoxy (meth)acrylates are preferred. In addition, the (meth)acrylic compound is preferably one having two or more (meth)acryloyl groups in one molecule from the viewpoint of reactivity. In this specification, the term "(meth)acrylate" means acrylate or methacrylate, and the term "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound have been reacted with (meth)acrylic acid.

[0015] 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 isoctyl (meth)acrylate. Somyristyl (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-tetrafluoropropionate Examples of the acrylates include 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, and glycidyl (meth)acrylate.

[0016] 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 the like. Examples of the di(meth)acrylate 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, dimethylol dicyclopentadienyl 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.

[0017] In addition, 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.

[0018] The epoxy (meth)acrylate may, for example, be one obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a basic catalyst according to a conventional method.

[0019] As the epoxy compound serving as a raw material for synthesizing the above-mentioned epoxy (meth)acrylate, the same epoxy compound as that described above as the curable resin contained in the sealant for liquid crystal display elements of the present invention can be used.

[0020] Among the above 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 KRM7985, and EBECRYL RDX63182. 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.

[0021] 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.

[0022] Examples of the isocyanate compound that is a raw material 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.

[0023] As the isocyanate compound serving as a 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.

[0024] Examples of the (meth)acrylic acid derivative 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)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. The epoxy (meth)acrylate may, for example, be bisphenol A type epoxy acrylate.

[0025] 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 Industries 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 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, EBECRYL9260, and the like. 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, Art Resin UN-9000H, etc. 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.

[0026] The ratio of (meth)acryloyl groups in the total of epoxy groups and (meth)acryloyl groups in the curable resin is preferably 30 mol % or more and 95 mol % or less. When the ratio of (meth)acryloyl groups is within this range, the resulting sealant for liquid crystal display elements has excellent adhesion and low liquid crystal contamination.

[0027] From the viewpoint of further suppressing contamination of the liquid crystal, the above-mentioned curable resin preferably has a hydrogen-bonding unit such as an -OH group, an -NH- group, or an -NH2 group.

[0028] The preferred lower limit of the total content of the curable resin in 100 parts by mass of the sealant for liquid crystal display elements of the present invention is 50 parts by mass, and the preferred upper limit is 90 parts by mass. When the total content of the curable resin is within this range, the resulting sealant for liquid crystal display 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 80 parts by mass.

[0029] The sealing agent for a liquid crystal display element of the present invention contains an organic filler. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, (meth)acrylic polymer fine particles, etc. The organic filler may have a core-shell structure.

[0030] The preferred lower limit of the average particle size of the organic filler is 0.1 μm, and the preferred upper limit is 0.8 μm. By setting the average particle size of the organic filler in this range, it becomes easier to adjust the shrinkage rate in the photocuring process, the maximum expansion rate in the heat curing process, and the shrinkage rate in the heat curing process to the above-mentioned ranges while maintaining the coating properties, etc. The more preferred upper limit of the average particle size of the organic filler is 0.5 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 measuring device. Examples of the particle size distribution measuring device include NICOMP 380ZLS (manufactured by PARTICLE SIZING SYSTEMS).

[0031] The content of the organic filler in 100 parts by mass of the sealant for liquid crystal display elements of the present invention is preferably 1 part by mass at the lower limit and 40 parts by mass at the upper limit. By having the content of the organic filler in this range, it becomes easier to adjust the shrinkage rate in the photocuring step, the maximum expansion rate in the heat curing step, and the shrinkage rate in the heat curing step to the above-mentioned ranges while maintaining the coatability, etc. The more preferred lower limit of the content of the organic filler is 10 parts by mass, and the more preferred upper limit is 30 parts by mass. In addition, the sealing agent for liquid crystal display elements of the present invention preferably has a total content of the epoxy compound and the organic filler of 1 / 3 or more of the total content of the curable resin. By having the total content of the epoxy compound and the organic filler of 1 / 3 or more of the total content of the curable resin, it becomes easier to adjust the shrinkage rate in the photocuring process, the maximum expansion rate in the heat curing process, and the shrinkage rate in the heat curing process to the above-mentioned ranges. It is more preferable that the total content of the epoxy compound and the organic filler is 1 / 2 or more of the total content of the curable resin. Furthermore, when the sealing agent for liquid crystal display elements of the present invention contains an inorganic filler described later, the content of the organic filler is preferably equal to or greater than the content of the inorganic filler. By having the content of the organic filler equal to or greater than the content of the inorganic filler, it becomes easier to adjust the shrinkage rate in the photocuring step, the maximum expansion rate in the heat curing step, and the shrinkage rate in the heat curing step to the above-mentioned ranges. It is more preferable that the content of the organic filler is 1.5 times or more the content of the inorganic filler.

[0032] The sealant for liquid crystal display elements of the present invention preferably contains an inorganic filler in addition to the organic filler for the purposes of increasing viscosity, improving adhesion due to a stress dispersion effect, improving the linear expansion coefficient, and the like.

[0033] 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.

[0034] The preferred lower limit of the content of the inorganic filler in 100 parts by mass of the sealant for liquid crystal display elements of the present invention is 1 part by mass, and the preferred upper limit is 30 parts by mass. By having the content of the inorganic filler in this range, the effect of improving adhesion while maintaining coatability, etc. is more excellent. The more preferred lower limit of the content of the inorganic filler is 5 parts by mass, and the more preferred upper limit is 15 parts by mass.

[0035] The sealing agent for liquid crystal display elements of the present invention preferably contains a photoradical polymerization initiator. Examples of the photoradical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, and thioxanthone compounds. Specific examples of the photoradical polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-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) 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-(acetoxyimino)-1-(4-(4-(2-hydroxyethoxy)phenylthio)phenyl)propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4-dimethylthioxanthen-9-one, and the like.

[0036] The content of the photoradical polymerization initiator is preferably 0.01 parts by mass at the lower limit and 10 parts by mass at the upper limit with respect to 100 parts by mass of the curable resin. By setting the content of the photoradical polymerization initiator within 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 photoradical polymerization initiator is 0.1 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0037] The sealing agent for liquid crystal display elements of the present invention preferably contains a thermal radical polymerization initiator. By using the thermal radical polymerization initiator, it becomes easier to adjust the maximum expansion rate and the shrinkage rate in the thermal curing step to the above-mentioned ranges.

[0038] Examples of the thermal radical polymerization initiator include azo compounds, organic peroxides, etc. Among these, azo compounds are preferred.

[0039] The azo compound may, for example, have a structure in which a plurality of units such as polyalkylene oxide or polydimethylsiloxane are bonded via an azo group. As the azo compound having a structure in which a plurality of units such as polyalkylene oxide are bonded via the azo group, those having a polyethylene oxide structure are preferred. Specific examples of the azo compound include 4,4'-azobis(4-cyanovaleric acid), a polycondensate of 4,4'-azobis(4-cyanopentanoic acid) and polyalkylene glycol, and a polycondensate of 4,4'-azobis(4-cyanopentanoic acid) and polydimethylsiloxane having a terminal amino group. Among the above azo compounds, 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.).

[0040] Examples of the organic peroxide include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxy esters, diacyl peroxides, and peroxydicarbonates.

[0041] The content of the thermal radical polymerization initiator is preferably 0.01 parts by mass at the lower limit and 10 parts by mass at the upper limit with respect to 100 parts by mass of the curable resin. By setting the content of the thermal radical polymerization initiator within this range, it becomes easier to adjust the maximum expansion rate and the shrinkage rate in the thermal curing process to the above-mentioned ranges. The more preferred lower limit of the content of the thermal radical polymerization initiator is 0.1 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0042] The sealing agent for liquid crystal display elements of the present invention preferably 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.

[0043] 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, examples of commercially available ones include 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 available from Otsuka Chemical Co., Ltd. include SDH and ADH. 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.

[0044] The content of the heat curing 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 heat curing agent within this range, the resulting sealant for liquid crystal display elements has excellent heat curing properties while maintaining storage stability and coatability. The more preferred upper limit of the content of the heat curing agent is 30 parts by mass.

[0045] 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 or the like. As the silane coupling agent, for example, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, etc. are suitably used.

[0046] The content of the silane coupling agent in 100 parts by mass of the sealant for liquid crystal display element of the present invention is preferably 0.1 parts by mass at the lower limit and 10 parts by mass at the upper limit. By the content of the silane coupling agent being within this range, the resulting sealant for liquid crystal display element is more excellent in the effect of improving adhesion while suppressing the occurrence of liquid crystal contamination. The content of the silane coupling agent is more preferably 0.3 parts by mass at the lower limit and 5 parts by mass at the upper limit.

[0047] The sealing material for liquid crystal display elements 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.

[0048] The method for producing the sealing agent for liquid crystal display elements of the present invention may be, for example, a method in which a curable resin, an organic filler, and other components such as a photoradical polymerization initiator are mixed using a mixer. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mixer.

[0049] Moreover, by blending conductive fine particles with the sealing agent for liquid crystal display elements of the present invention, a vertically conductive material can be produced. The conductive fine particles may be metal balls, fine resin particles having a conductive metal layer formed on the surface thereof, etc. Among them, fine resin particles having a conductive metal layer formed on the surface thereof are preferable because the excellent elasticity of the fine resin particles allows conductive connection without damaging a transparent substrate, etc.

[0050] As a method for producing a liquid crystal display element using the sealant for a liquid crystal display element of the present invention, a liquid crystal dropping method is suitably used, and specifically, for example, a method having the following steps can be mentioned. First, a process 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 process is performed in which minute droplets of liquid crystal are dropwise applied to the entire surface within the frame of the seal pattern, and the other transparent substrate is superimposed under vacuum. After that, a liquid crystal display element can be obtained by a process of irradiating the seal pattern portion with light such as ultraviolet light to provisionally cure the sealant (photocuring process), and a process of heating the provisionally cured sealant to fully cure it (thermal curing process).

[0051] The sealant for liquid crystal display elements of the present invention can suppress peeling of the substrate even when applied at high density to large mother glass, and therefore can be suitably used particularly when applied to mother glass of so-called 8th generation or later sizes of 2200 mm x 2400 mm or 2160 mm x 2460 mm or more. Effect of the Invention

[0052] According to the present invention, it is possible to provide a sealant for liquid crystal display elements which has excellent adhesiveness and can prevent peeling of the substrate even when applied at high density to a large mother glass. [Brief description of the drawings]

[0053] [Figure 1]1 is a graph showing an example of the relationship between each process and the shrinkage rate or expansion rate of a sealant for a liquid crystal display element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0055] (Examples 1 to 8, 10 to 13, 15, 21, 23 ,three Examples 9, 14, 16~20, 22, 24 、25 , Comparative Examples 1 to 5) According to the compounding ratios shown in Tables 1 to 3, each material was stirred with a planetary stirrer, and then uniformly mixed with a ceramic three-roll mill to produce the compositions shown in Examples 1 to 8, 10 to 13, 15, 21, and 23. ,three Examples 9, 14, 16~20, 22, 24 、25 Thus, sealing agents for liquid crystal display elements were obtained for Comparative Examples 1 to 5. Awatori Rentaro (manufactured by Thinky Corporation) was used as the planetary mixing device.

[0056] (Shrinkage rate during the light curing process, maximum expansion rate during the heat curing process, and shrinkage rate during the heat curing process) The shrinkage rate during the photocuring process, the maximum expansion rate during the heat curing process, and the shrinkage rate during the heat curing process of the obtained sealant for liquid crystal display elements were measured using a resin curing shrinkage measuring device in accordance with JIS K 6941. The resin curing shrinkage measuring device used was Custron (manufactured by Acroedge Co., Ltd.). The results are shown in Tables 1 to 3.

[0057] (glass transition temperature) Each of the obtained sealants for liquid crystal display elements was subjected to a high-pressure mercury lamp, a cut filter that cuts out light of 340 nm or less, and an illumination intensity of 100 mW / cm 2After a photocuring step of irradiating the resin with ultraviolet light for 30 seconds, a heat curing step of heating the resin at 130°C for 60 minutes was carried out to obtain a cured product. The cured product after the heat curing step was subjected to dynamic viscoelasticity measurement using a dynamic viscoelasticity measuring device under the conditions of a test piece width of 5 mm, a thickness of 0.35 mm, a gripping width of 25 mm, a heating rate of 10°C / min, a temperature range of -80°C to 200°C, and a frequency of 10 Hz, and the temperature at the maximum value of the loss tangent (tan δ) was determined as the glass transition temperature. The dynamic viscoelasticity measuring device used was a DVA-200 (manufactured by IT Keisoku Seigyo Co., Ltd.). The results are shown in Tables 1 to 3.

[0058] <Evaluation> Working Example , reference example, and 、 The sealants for liquid crystal display elements obtained in the comparative examples were evaluated as follows. The results are shown in Tables 1 to 3.

[0059] (Adhesion (compressive shear adhesive strength)) The obtained sealant for liquid crystal display elements was applied in dots to one of two ITO substrates, each 45 mm long, 25 mm wide, and 0.7 mm thick, so that the diameter when bonded would be 3 mm. The other ITO substrate was placed on top of the ITO substrate with the sealant applied in dots, shifted by 10 mm in the longitudinal direction, with the sealant in between. After that, a high-pressure mercury lamp was used to illuminate the substrate at an illuminance of 100 mW / cm through a cut filter that can cut off wavelengths of 340 nm or less. 2 After irradiating the sealant with ultraviolet light for 30 seconds, the sealant was cured by heating at 130°C for 60 minutes to obtain a test specimen. The compressive shear adhesive strength of the obtained test specimen at 25°C was measured using an Autograph AGX (manufactured by Shimadzu Corporation) according to the method in accordance with JIS K 6852.

[0060] [Table 1]

[0061] [Table 2]

[0062] [Table 3] [Industrial Applicability]

[0063] According to the present invention, it is possible to provide a sealant for liquid crystal display elements which has excellent adhesiveness and can prevent peeling of the substrate even when applied at high density to a large mother glass.

Claims

[Claim 1] A sealant for liquid crystal display elements, comprising a curable resin, a thermal radical polymerization initiator, an organic filler, and an inorganic filler, and having photocurability and thermosetting properties, the curable resin contains an epoxy compound and a (meth)acrylic compound, a total content of the epoxy compound and the organic filler is 1 / 3 or more of the total content of the curable resin; The content of the organic filler is 1.5 times or more the content of the inorganic filler, when a photo-curing step is performed in which the uncured sealant for liquid crystal display elements is irradiated with ultraviolet light having a wavelength of 300 to 500 nm and an illuminance of 100 mW / cm 2 for 30 seconds using a high-pressure mercury lamp, the shrinkage rate of the uncured sealant for liquid crystal display elements after the photo-curing step at 25° C. is 3.5% or less; After the photocuring step, when the temperature of the sealant for liquid crystal display elements is increased to 130° C. at a temperature increase rate of 10° C. / min and then heated at 130° C. for 60 minutes in a heat curing step, the maximum expansion coefficient of the sealant for liquid crystal display elements during the heat curing step relative to the uncured sealant for liquid crystal display elements is 1.5% or more and less than 4%, and When the heat curing step is performed after the light curing step, the shrinkage rate of the sealant for liquid crystal display elements during the heat curing step from the time when the sealant for liquid crystal display elements shows a maximum expansion rate to the end of the heat curing step is 0.1% or more, A sealant for liquid crystal display elements, characterized in that when the heat curing step is carried out after the light curing step, the glass transition temperature of the cured product after the heat curing step is 80° C. or higher and 110° C. or lower.

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