Sealant for liquid crystal elements

Abstract

The present invention provides a sealant for liquid crystal devices that is excellent in storage stability, adhesiveness, and low liquid crystal contamination. The present invention provides a sealant for liquid crystal devices, which comprises a curable resin, a thermosetting agent, and a (poly)alkylene glycol, wherein the curable resin contains an epoxy compound.

Description

[Technical Field]

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

[0002] In recent years, liquid crystal display elements have been widely used as display elements characterized by their thinness, light weight, low power consumption, etc. Furthermore, liquid crystal light control elements using liquid crystal materials have been widely used as light control elements whose light transmittance changes when a voltage is applied. In such liquid crystal display elements and liquid crystal light control elements, a sealant is usually used for bonding various components and sealing the liquid crystal.

[0003] For example, a liquid crystal display element manufacturing method known as a liquid crystal dropping method using a sealant, as disclosed in Patent Documents 1 and 2, is used 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 electrode-equipped substrates. Next, while the sealant is still uncured, minute droplets of liquid crystal are dropped into the frame of the seal pattern. After the other substrate is superimposed under vacuum, the sealant is cured to produce a liquid crystal display element. This dropping method is currently the mainstream method for manufacturing liquid crystal display elements. Furthermore, for example, Patent Document 3 discloses the use of a material containing an epoxy compound as a sealant that surrounds the liquid crystal layer of a light control unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-133794 [Patent Document 2] International Publication No. 02 / 092718 [Patent Document 3] Patent Publication No. 2021-117456 Summary of the Invention [Problem to be solved by the invention]

[0005] In today's world, where mobile devices with various display panels, such as mobile phones and portable game consoles, are becoming more and more common, miniaturizing these devices is a major challenge. One method for miniaturizing devices is to narrow the frame of the display, for example by positioning the seal under the black matrix (hereinafter referred to as a narrow frame design). In narrow frame designs, the sealant is positioned directly below the black matrix. Therefore, if a drop-on method is used, the light irradiated during photo-curing of the sealant is blocked, making it difficult for the light to reach the interior of the sealant, resulting in insufficient curing. When photo-curing of the sealant is difficult, heat curing is performed. To heat-cure the sealant, a heat-curing agent is typically blended into the sealant. However, to accommodate future narrow cell gaps in display devices and light-control devices, it is considered to use a heat-curing agent with a low melting point. However, low-melting-point heat-curing agents, such as imidazole-based heat-curing agents, have low reactivity due to catalytic reactions, resulting in the resulting sealant having poor curing and adhesive properties. On the other hand, using a highly reactive heat-curing agent to improve the curing and adhesive properties of the sealant can result in the resulting sealant having poor storage stability or contaminating the liquid crystal.

[0006] An object of the present invention is to provide a sealant for liquid crystal elements that is excellent in storage stability, adhesiveness, and low liquid crystal contamination. [Means for solving the problem]

[0007] Disclosure 1 is a sealant for liquid crystal devices that contains a curable resin, a thermosetting agent, and a (poly)alkylene glycol, and the curable resin contains an epoxy compound. Disclosure 2 is the sealant for liquid crystal elements according to Disclosure 1, wherein the content of the (poly)alkylene glycol relative to 100 parts by mass of the curable resin is 0.1 parts by mass or more and 5 parts by mass or less. Disclosure 3 is a sealant for liquid crystal elements according to Disclosure 1 or 2, wherein the epoxy compound includes a polyfunctional epoxy compound having two or more epoxy groups in one molecule, and the content of the (poly)alkylene glycol relative to 100 parts by mass of the polyfunctional epoxy compound is 0.5 parts by mass or more and 25 parts by mass or less. Disclosure 4 is the sealant for liquid crystal devices according to Disclosure 1, 2, or 3, wherein the content of the (poly)alkylene glycol per 100 parts by mass of the heat curing agent is 2.5 parts by mass or more and 125 parts by mass or less. Disclosure 5 is the sealant for a liquid crystal device according to Disclosure 1, 2, 3, or 4, wherein the (poly)alkylene glycol contains diethylene glycol. The present disclosure 6 is the sealant for liquid crystal devices according to the present disclosure 1, 2, 3, 4 or 5, wherein the heat curing agent comprises at least one selected from the group consisting of an imidazole adduct of an epoxy compound and an imidazole compound. The present disclosure 7 is the sealant for a liquid crystal device according to the present disclosure 1, 2, 3, 4, 5 or 6, further comprising a radical polymerization initiator. The present disclosure 8 is the sealant for a liquid crystal device according to the present disclosure 1, 2, 3, 4, 5, 6 or 7, further comprising a silane coupling agent. Disclosure 9 is a sealant for a liquid crystal element according to Disclosure 1, 2, 3, 4, 5, 6, 7 or 8, used in the manufacture of a liquid crystal element by a liquid crystal dropping method. The present invention will be described in detail below.

[0008] The present inventors have found that by further adding a (poly)alkylene glycol to a sealant for liquid crystal elements containing an epoxy compound and a thermosetting agent, it is possible to obtain a sealant for liquid crystal elements that is excellent in storage stability, adhesiveness, and low liquid crystal contamination, and have completed the present invention.

[0009] The sealing agent for liquid crystal elements of the present invention contains a (poly)alkylene glycol. By using the (poly)alkylene glycol in combination with an epoxy compound and a heat curing agent, the sealant for liquid crystal elements of the present invention becomes excellent in storage stability, adhesiveness, and low liquid crystal contamination. In this specification, the term "(poly)alkylene glycol" refers collectively to alkylene glycols having only one alkylene group in one molecule and polyalkylene glycols having two or more alkylene groups in one molecule.

[0010] Examples of the (poly)alkylene glycol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,2-butanediol, 2,3-butanediol, 1,4-butanediol, 1,6-hexanediol, etc. Among these, the (poly)alkylene glycol is preferably a liquid (poly)alkylene glycol, and more preferably contains diethylene glycol, since the resulting sealant for liquid crystal elements will have better adhesion and less liquid crystal contamination. In this specification, the term "liquid" means that the material is fluid at 23°C.

[0011] The preferred lower limit of the content of the (poly)alkylene glycol relative to 100 parts by mass of the curable resin described below is 0.1 parts by mass, and the preferred upper limit is 5 parts by mass. When the content of the (poly)alkylene glycol relative to 100 parts by mass of the curable resin is 0.1 parts by mass or more, the sealant for liquid crystal elements of the present invention will have better adhesive properties. When the content of the (poly)alkylene glycol relative to 100 parts by mass of the curable resin is 5 parts by mass or less, the sealant for liquid crystal elements of the present invention will have better adhesive properties and reduced liquid crystal contamination. A more preferred lower limit of the content of the (poly)alkylene glycol relative to 100 parts by mass of the curable resin is 0.5 parts by mass, a more preferred upper limit is 3 parts by mass, and an even more preferred lower limit is 1 part by mass. Furthermore, when the epoxy compound described below includes a polyfunctional epoxy compound having two or more epoxy groups per molecule, the preferred lower limit of the content of the (poly)alkylene glycol relative to 100 parts by mass of the polyfunctional epoxy compound is 0.5 parts by mass, and the preferred upper limit is 25 parts by mass. When the content of the (poly)alkylene glycol relative to 100 parts by mass of the polyfunctional epoxy compound is 0.5 parts by mass or more, the resulting sealant for liquid crystal devices has superior adhesive properties. When the content of the (poly)alkylene glycol relative to 100 parts by mass of the polyfunctional epoxy compound is 25 parts by mass or less, the resulting sealant for liquid crystal devices has superior adhesive properties and low liquid crystal contamination. A more preferred lower limit of the content of the (poly)alkylene glycol relative to 100 parts by mass of the polyfunctional epoxy compound is 1.5 parts by mass, and the more preferred upper limit is 4 parts by mass. Furthermore, the preferred lower limit of the content of the (poly)alkylene glycol relative to 100 parts by mass of the heat curing agent described below is 2.5 parts by mass, and the preferred upper limit is 125 parts by mass. When the content of the (poly)alkylene glycol relative to 100 parts by mass of the heat curing agent is 2.5 parts by mass or more, the resulting sealant for liquid crystal elements has superior adhesive properties. When the content of the (poly)alkylene glycol relative to 100 parts by mass of the heat curing agent is 125 parts by mass or less, the resulting sealant for liquid crystal elements has superior adhesive properties and low liquid crystal contamination. A more preferred lower limit of the content of the (poly)alkylene glycol relative to 100 parts by mass of the heat curing agent is 5 parts by mass, and a more preferred upper limit is 100 parts by mass.

[0012] The sealant for liquid crystal elements of the present invention contains a curable resin. The curable resin includes an epoxy compound. From the viewpoint of curability and adhesiveness, the epoxy compound preferably contains a polyfunctional epoxy compound having two or more epoxy groups in one molecule.

[0013] Examples of the polyfunctional 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, 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 epoxy compounds, and glycidyl ester compounds.

[0014] Commercially available examples of the bisphenol A epoxy compounds include jER828EL and jER1004 (both manufactured by Mitsubishi Chemical Corporation), and EPICLON850 (manufactured by DIC Corporation). Commercially available examples of the bisphenol F epoxy compounds include jER806 and 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 examples include EPICLON EXA-1514 (manufactured by DIC Corporation). Among the above 2,2'-diallylbisphenol A type epoxy compounds, a commercially available one is, for example, RE-810NM (manufactured by Nippon Kayaku Co., Ltd.). Among the hydrogenated bisphenol epoxy compounds, commercially available examples include 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 resorcinol type epoxy compounds, commercially available examples include EX-201 (manufactured by Nagase ChemteX Corporation). Among the biphenyl type epoxy compounds, commercially available examples include jER YX-4000H (manufactured by Mitsubishi Chemical Corporation). Among the sulfide-type epoxy compounds, commercially available examples include YSLV-50TE (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Among the diphenyl ether type epoxy compounds, commercially available ones include, for example, YSLV-80DE (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Among the 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 examples include EPICLON HP-4032 and EPICLON EXA-4700 (both manufactured by DIC Corporation). Among the above phenol novolac type epoxy compounds, commercially available ones include, for example, EPICLON N-770 (manufactured by DIC Corporation). Among the above ortho-cresol novolac epoxy compounds, commercially available examples include EPICLON N-670-EXP-S (manufactured by DIC Corporation). Among the dicyclopentadiene novolac epoxy compounds, commercially available examples include EPICLON HP-7200 (manufactured by DIC Corporation). Among the biphenyl novolac epoxy compounds, commercially available examples include NC-3000P (manufactured by Nippon Kayaku Co., Ltd.). Among the above naphthalenephenol novolac type epoxy compounds, commercially available examples include ESN-165S (manufactured by Nippon Steel Chemical & Material Co., Ltd.). Commercially available examples of the glycidylamine type epoxy compounds include jER630 (manufactured by Mitsubishi Chemical Corporation), EPICLON430 (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.), EPICLON726 (manufactured by DIC Corporation), Epolite 80MFA (manufactured by Kyoeisha Chemical Co., Ltd.), and Denacol EX-611 (manufactured by Nagase ChemteX Corporation). Among the rubber-modified epoxy compounds, commercially available examples include YR-450 and 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 examples include 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.).

[0015] 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 refers to 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 portion of the epoxy groups in an epoxy compound having two or more epoxy groups with (meth)acrylic acid. Furthermore, in this specification, the term "(meth)acrylic" refers to acrylic or methacrylic, and the term "(meth)acryloyl" refers to acryloyl or methacryloyl. When the partially (meth)acrylic-modified epoxy compound is a compound having one epoxy group and one (meth)acryloyl group in one molecule, it is treated as a monofunctional epoxy compound.

[0016] Among the partially (meth)acrylic-modified epoxy compounds, commercially available examples include UVACURE1561 and KRM8287 (both manufactured by Daicel-Allnex Corporation).

[0017] The preferred lower limit of the content of the epoxy compound in 100 parts by mass of the curable resin is 5 parts by mass, and the preferred upper limit is 70 parts by mass. By having the content of the epoxy compound in this range, the resulting sealant for liquid crystal elements will have better adhesion and less liquid crystal contamination. The more preferred lower limit of the content of the epoxy compound is 10 parts by mass, and the more preferred upper limit is 60 parts by mass. Furthermore, the epoxy compound may consist solely of the polyfunctional epoxy compound. However, when the epoxy compound contains a combination of a monofunctional epoxy compound having one epoxy group per molecule and the polyfunctional epoxy compound, from the viewpoint of making the resulting sealant for liquid crystal elements more excellent in storage stability, adhesiveness, and low liquid crystal contamination, the lower limit of the content of the polyfunctional epoxy compound per 100 parts by mass of the epoxy compound is preferably 10 parts by mass, the upper limit is preferably 60 parts by mass, the more preferably 15 parts by mass, and the more preferably 50 parts by mass.

[0018] The curable resin may contain a (meth)acrylic compound. In particular, from the viewpoint of achieving excellent low liquid crystal contamination properties, the curable resin preferably contains the (meth)acrylic compound.

[0019] 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)acrylic compound" refers to a compound having a (meth)acryloyl group other than the partially (meth)acrylic-modified epoxy compound. 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.

[0020] 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.

[0021] Furthermore, examples of the bifunctional (meth)acrylic acid ester compounds include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, Examples of suitable bisphenol A di(meth)acrylates include butyl di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-added bisphenol A di(meth)acrylate, propylene oxide-added bisphenol A di(meth)acrylate, ethylene oxide-added bisphenol F di(meth)acrylate, dimethyloldicyclopentadienyl di(meth)acrylate, ethylene oxide-modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polycaprolactone diol di(meth)acrylate, and polybutadiene diol di(meth)acrylate.

[0022] 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.

[0023] The epoxy (meth)acrylate may be, for example, one obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a basic catalyst according to a conventional method.

[0024] As the epoxy compound serving as a raw material for synthesizing the above-mentioned epoxy (meth)acrylate, the same polyfunctional epoxy compound as described above as the curable resin contained in the sealing agent for liquid crystal elements of the present invention can be used.

[0025] Among the above-mentioned epoxy (meth)acrylates, commercially available ones include, for example, epoxy (meth)acrylate manufactured by Daicel Allnex Corporation, epoxy (meth)acrylate manufactured by Shin-Nakamura Chemical Co., Ltd., epoxy (meth)acrylate manufactured by Kyoeisha Chemical Co., Ltd., and epoxy (meth)acrylate manufactured by Nagase ChemteX Corporation. Examples of the epoxy (meth)acrylates manufactured by Daicel-Allnex include EBECRYL860, EBECRYL3200, EBECRYL3201, EBECRYL3412, EBECRYL3600, EBECRYL3700, EBECRYL3701, EBECRYL3702, EBECRYL3703, EBECRYL3708, EBECRYL3800, EBECRYL6040, 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.

[0026] 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.

[0027] Examples of isocyanate compounds that can be used as raw materials for the urethane (meth)acrylate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatephenyl)thiophosphate, tetramethylxylylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0028] Furthermore, as the isocyanate compound that is the raw material for the urethane (meth)acrylate, a chain-extended isocyanate compound obtained by reacting a polyol with an excess of an isocyanate compound can also be used. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0029] Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl mono(meth)acrylate, mono(meth)acrylate of a dihydric alcohol, mono(meth)acrylate or di(meth)acrylate of a trihydric alcohol, and epoxy(meth)acrylate. 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. Examples of the epoxy(meth)acrylate include bisphenol A type epoxy(meth)acrylate.

[0030] Among the above-mentioned urethane (meth)acrylates, commercially available ones include, for example, urethane (meth)acrylate manufactured by Toagosei Co., Ltd., urethane (meth)acrylate manufactured by Daicel-Allnex Corporation, urethane (meth)acrylate manufactured by Negami Chemical Industries, Ltd., urethane (meth)acrylate manufactured by Shin-Nakamura Chemical Co., Ltd., and urethane (meth)acrylate manufactured by Kyoeisha Chemical Co., Ltd. Examples of the urethane (meth)acrylates manufactured by Toagosei Co., Ltd. include M-1100, M-1200, M-1210, and M-1600. Examples of the urethane (meth)acrylates manufactured by Daicel-Allnex include EBECRYL210, EBECRYL220, EBECRYL230, EBECRYL270, EBECRYL1290, EBECRYL2220, EBECRYL4827, EBECRYL4842, EBECRYL4858, EBECRYL5129, EBECRYL6700, EBECRYL8402, EBECRYL8803, EBECRYL8804, EBECRYL8807, and EBECRYL9260. Examples of urethane (meth)acrylates manufactured by Negami Chemical Industrial Co., Ltd. include Art Resin UN-330, Art Resin SH-500B, Art Resin UN-1200TPK, Art Resin UN-1255, Art Resin UN-3320HB, Art Resin UN-7100, Art Resin UN-9000A, and Art Resin UN-9000H. Examples of the urethane (meth)acrylates manufactured by Shin-Nakamura Chemical Co., Ltd. include U-2HA, U-2PHA, U-3HA, U-4HA, U-6H, U-6HA, U-6LPA, U-10H, U-15HA, U-108, U-108A, U-122A, U-122P, U-324A, U-340A, U-340P, U-1084A, U-2061BA, UA-340P, UA-4000, UA-4100, UA-4200, UA-4400, UA-5201P, UA-7100, UA-7200, and UA-W2A. Examples of the urethane (meth)acrylates manufactured by Kyoeisha Chemical Co., Ltd. include AH-600, AI-600, AT-600, UA-101I, UA-101T, UA-306H, UA-306I, and UA-306T.

[0031] From the viewpoint of further suppressing contamination of the liquid crystal, the curable resin preferably has a hydrogen-bonding unit such as an -OH group, an -NH- group, or an -NH2 group.

[0032] The preferred lower limit of the total content of the curable resin in 100 parts by mass of the sealant for liquid crystal elements of the present invention is 40 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 elements has better curability and adhesiveness. The more preferred lower limit of the total content of the curable resin is 50 parts by mass, and the more preferred upper limit is 80 parts by mass.

[0033] The sealant for liquid crystal elements of the present invention contains a thermosetting agent, which is an epoxy curing agent that contributes to the curing reaction of the epoxy compound.

[0034] The above-mentioned thermosetting agent preferably has a melting point of 120° C. or less, from the viewpoint of responding to the trend toward a smaller cell gap in liquid crystal elements. The melting point of the thermosetting agent can be determined by differential scanning calorimetry or by measurement using a commercially available melting point measuring device.

[0035] The heat curing agent preferably contains at least one selected from the group consisting of imidazole adducts of epoxy compounds (hereinafter simply referred to as "imidazole adducts") and imidazole compounds. By including at least one selected from the group consisting of the imidazole adduct and the imidazole compound as the heat curing agent in combination with the epoxy compound and the (poly)alkylene glycol, the resulting sealant for liquid crystal elements has better storage stability, adhesion, and low liquid crystal contamination.

[0036] The imidazole adduct has a structure derived from an epoxy compound and a structure derived from an imidazole compound.

[0037] Examples of epoxy compounds from which the imidazole adduct is derived include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol E type epoxy compounds, bisphenol S type epoxy compounds, 2,2'-diallyl bisphenol A type epoxy compounds, hydrogenated bisphenol type epoxy compounds, propylene oxide-added bisphenol A type epoxy compounds, resorcinol type epoxy compounds, biphenyl type epoxy compounds, sulfide type epoxy compounds, diphenyl ether type epoxy compounds, dicyclopentadiene type epoxy compounds, naphthalene type epoxy compounds, phenol novolac type epoxy compounds, o-cresol novolac type epoxy compounds, dicyclopentadiene novolac type epoxy compounds, biphenyl novolac type epoxy compounds, naphthalene phenol novolac type epoxy compounds, glycidylamine type epoxy compounds, alkyl polyol type epoxy compounds, rubber-modified type epoxy compounds, and glycidyl ester compounds.

[0038] Examples of imidazole compounds from which the imidazole adducts are derived include 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct.

[0039] The weight-average molecular weight of the imidazole adduct is preferably 500 at its lower limit and 1500 at its upper limit. When the weight-average molecular weight of the imidazole adduct is within this range, the resulting sealant for liquid crystal elements has excellent handling properties and low liquid crystal contamination. The weight-average molecular weight of the imidazole adduct is more preferably 1000 at its lower limit and 1200 at its upper limit. In this specification, the weight-average molecular weight is a value determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted into polystyrene. Examples of columns used for measuring the weight-average molecular weight converted into polystyrene by GPC include Shodex LF-804 (manufactured by Showa Denko K.K.).

[0040] Examples of the imidazole compound used as the thermal curing agent include 2-methylimidazole, 2-propylimidazole, N-methylimidazole, N-propylimidazole, N-butylimidazole, 1-(2-hydroxyethyl)imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, and 2-hydroxybenzimidazole.

[0041] The heat curing agent may contain other heat curing agents in addition to the imidazole adduct and the imidazole compound, as long as the object of the present invention is not impaired. Examples of the other heat curing agents include organic acid hydrazides, polyhydric phenol compounds, and acid anhydrides.

[0042] The preferred lower limit of the content of the thermosetting agent relative to 100 parts by mass of the curable resin is 0.1 parts by mass, and the preferred upper limit is 10 parts by mass. By having the content of the thermosetting agent within this range, the resulting sealant for liquid crystal elements will have better storage stability, thermosetting properties, and low liquid crystal contamination. The more preferred lower limit of the content of the thermosetting agent is 0.5 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0043] The sealant for a liquid crystal element of the present invention may contain a radical polymerization initiator. In particular, from the viewpoint of achieving excellent low liquid crystal contamination properties, the sealant for a liquid crystal element of the present invention preferably contains the above-mentioned (meth)acrylic compound and the above-mentioned radical polymerization initiator in combination.

[0044] The radical polymerization initiator may be a photoradical polymerization initiator or a thermal radical polymerization initiator. Among them, the photoradical polymerization initiator is preferred from the viewpoint of making the resulting sealing agent for liquid crystal elements excellent in photocurability. Furthermore, from the viewpoint of making the sealing agent for liquid crystal elements excellent in low liquid crystal contamination, it is also preferred to contain the thermal radical polymerization initiator as the radical polymerization initiator.

[0045] 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, 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), and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. The photoradical polymerization initiators may be used alone or in combination of two or more.

[0046] Examples of the thermal radical polymerization initiator include those composed of an azo compound, an organic peroxide, etc. Among them, from the viewpoint of suppressing contamination of the liquid crystal by the thermal radical polymerization initiator, an initiator composed of an azo compound (hereinafter also referred to as "azo initiator") is preferred. The thermal radical polymerization initiators may be used alone or in combination of two or more.

[0047] Examples of the azo compound include 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(isobutyrate) dimethyl, 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. Examples of the azo initiator include V-501, V-65, VPE-0201, VPE-0401, VPE-0601, VPS-0501, and VPS-1001 (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0048] Examples of the organic peroxide include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, and peroxydicarbonates.

[0049] The preferred lower limit of the content of the radical polymerization initiator relative to 100 parts by mass of the curable resin is 0.1 parts by mass, and the preferred upper limit is 10 parts by mass. By having the content of the radical polymerization initiator within this range, the resulting sealant for liquid crystal devices will have better storage stability and curability. The more preferred lower limit of the content of the radical polymerization initiator is 0.3 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0050] The sealant for liquid crystal elements of the present invention may further contain a filler for the purposes of improving viscosity, improving adhesion due to a stress dispersion effect, improving the linear expansion coefficient, and improving the moisture resistance of the cured product.

[0051] As the filler, inorganic fillers and organic fillers can be used. 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. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and acrylic polymer fine particles. The above fillers may be used alone or in combination of two or more.

[0052] The preferred lower limit of the filler content per 100 parts by mass of the curable resin is 10 parts by mass, and the preferred upper limit is 70 parts by mass. By having the filler content within this range, excellent effects such as improved adhesion can be achieved without deteriorating the coating properties, etc. The more preferred upper limit of the filler content is 60 parts by mass.

[0053] The sealant for liquid crystal elements of the present invention may further contain a silane coupling agent. The silane coupling agent mainly serves as an adhesion aid for favorably adhering the sealant for liquid crystal elements to a substrate or the like. In addition, the silane coupling agent can chemically bond with the curable resin to prevent the curable resin from leaking into the liquid crystal.

[0054] As the silane coupling agent, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-isocyanatopropyltrimethoxysilane are preferably used because they are highly effective in improving adhesion to substrates, etc. Among these, 3-glycidoxypropyltrimethoxysilane is preferred. The above silane coupling agents may be used alone or in combination of two or more kinds.

[0055] The preferred lower limit of the content of the silane coupling agent in 100 parts by mass of the curable resin 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 effect of improving adhesion is more excellent, and liquid crystal contamination by the silane coupling agent can be suppressed. 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.

[0056] The sealing agent for liquid crystal elements of the present invention may further contain additives such as a light-shielding agent, a stress relaxation agent, a reactive diluent, a thixotropic agent, a spacer, a curing accelerator, an antifoaming agent, a leveling agent, and a polymerization inhibitor, as necessary.

[0057] Examples of a method for producing the sealing agent for liquid crystal elements of the present invention include a method of mixing a curable resin, a heat curing agent, a (poly)alkylene glycol, and a radical polymerization initiator, which is added as needed, 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.

[0058] By blending conductive fine particles into the sealing agent for liquid crystal elements of the present invention, a vertically conductive material can be produced. The conductive fine particles may be, for example, metal balls, fine resin particles with a conductive metal layer formed on the surface thereof, etc. Among these, fine resin particles with a conductive metal layer formed on the surface thereof are preferred because they can achieve conductive connection without damaging transparent substrates, etc., due to the excellent elasticity of the fine resin particles.

[0059] The sealant for liquid crystal elements of the present invention can be suitably used in the production of liquid crystal elements by a liquid crystal dropping method. Examples of the method for producing a liquid crystal element by the liquid crystal dropping method using the sealant for liquid crystal elements of the present invention include the following method. First, a process is performed in which a frame-shaped seal pattern is formed on a substrate by screen printing, dispenser application, or the like using the sealant for liquid crystal elements of the present invention. Next, while the sealant for liquid crystal elements of the present invention is still in an uncured state, minute droplets of liquid crystal are dropwise applied to the entire frame of the seal pattern, and another substrate is immediately superimposed on the substrate. A liquid crystal element can then be obtained by a method in which the sealant is heated and cured. Furthermore, a process of temporarily curing the sealant by irradiating the seal pattern with light such as ultraviolet light may be performed before the process of heating and curing the sealant.

[0060] The liquid crystal element manufactured using the sealant for liquid crystal elements of the present invention is preferably a liquid crystal element with a narrow frame design, specifically, the width of the frame around the display area is preferably 2 mm or less. Furthermore, when producing the liquid crystal element of the present invention, the application width of the sealant for a liquid crystal element of the present invention is preferably 1 mm or less. Examples of liquid crystal elements produced using the sealant for liquid crystal elements of the present invention include liquid crystal display elements and liquid crystal light control elements. [Effects of the Invention]

[0061] According to the present invention, it is possible to provide a sealant for liquid crystal elements that is excellent in storage stability, adhesiveness, and low liquid crystal contamination. DETAILED DESCRIPTION OF THE INVENTION

[0062] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0063] (Example 1 19. Reference Examples 20, Comparative Examples 1 to 5) According to the blending ratios shown in Tables 1 to 3, the materials were mixed using a planetary mixer (Thinky Corporation, "Awatori Rentaro"), and then further mixed using a three-roll mill to produce Examples 1 to 3. 19. Reference Examples 20. Sealant for liquid crystal devices of Comparative Examples 1 to 5 were prepared.

[0064] <Evaluation> The following evaluations were carried out on each of the obtained sealants for liquid crystal devices, and the results are shown in Tables 1 to 3.

[0065] (Storage stability) The initial viscosity of each of the resulting sealants for liquid crystal devices was measured immediately after production, and after storage at 25°C for 48 hours. The viscosity increase ratio was defined as (viscosity after storage) / (initial viscosity), and the storage stability was evaluated according to the following criteria. The viscosity of the sealants for liquid crystal devices was measured using an E-type viscometer (BROOK FIELD, "DV-III") at 25°C and a rotation speed of 1.0 rpm. ◎: When the viscosity increase rate is less than 1.5 ○: When the viscosity increase rate is 1.5 or more and less than 2.0 ×: When the viscosity increase rate is 2.0 or more

[0066] (Adhesiveness) One part by mass of spacer particles (Micropearl SP-2050, manufactured by Sekisui Chemical Co., Ltd.) with an average particle size of 4 μm was uniformly dispersed in 100 parts by mass of each of the obtained sealants for liquid crystal devices using a planetary stirrer. A very small amount of the sealant for liquid crystal devices with the spacer particles dispersed therein was placed in the center of a glass substrate (20 mm x 45 mm x 0.7 mm thick) with an ITO thin film, and another glass substrate with the same type of ITO thin film was placed on top of it. The sealant for liquid crystal devices was spread, and a metal halide lamp was used to illuminate the surface at 100 mW / cm. 2 After irradiation with ultraviolet light (wavelength 365 nm) for 30 seconds, the sealant for liquid crystal elements was cured by heating at 120°C for 1 hour to obtain an adhesion test piece. The sealant for liquid crystal elements obtained in Example 6 was cured by heating at 120°C for 1 hour without irradiation with ultraviolet light to obtain an adhesion test piece. The adhesive strength of each of the obtained adhesion test pieces was measured using a tension gauge, and the adhesiveness to the alignment film was evaluated according to the following criteria. ◎: Adhesion strength is 2.5 kg / cm or more ○: Adhesion strength was 2.0 kg / cm or more and less than 2.5 kg / cm △: When the adhesive strength was 1.5 kg / cm or more and less than 2.0 kg / cm ×: Adhesion strength was less than 1.5 kg / cm

[0067] (Low liquid crystal contamination) One part by mass of spacer particles (Micropearl SP-2050, manufactured by Sekisui Chemical Co., Ltd.) with an average particle size of 4 μm was uniformly dispersed in 100 parts by mass of each liquid crystal element sealant using a planetary stirrer. The liquid crystal element sealant with the dispersed spacer particles was filled into a syringe and degassed using a centrifugal degassing machine (Awatron AW-1). The degassed liquid crystal element sealant was applied in a frame shape to one of two alignment film and ITO-coated substrates using a dispenser under conditions of a nozzle diameter of 0.4 mm, a nozzle gap of 42 μm, a syringe discharge pressure of 100 to 400 kPa, and a coating speed of 60 mm / sec. The discharge pressure was adjusted so that the line width of the liquid crystal element sealant was approximately 1.0 mm. Next, minute droplets of liquid crystal (Tokyo Chemical Industry Co., Ltd., "4-pentyl-4-biphenylcarbonitrile") were applied dropwise to the entire surface of the frame of the liquid crystal element sealant on the substrate coated with the liquid crystal element sealant, and after leaving it for 2 hours, the other substrate was bonded under vacuum. After leaving the bonded substrates for 15 minutes after bonding, a metal halide lamp was used to illuminate the liquid crystal element sealant area at 100 mW / cm. 2 The sealant for liquid crystal elements was pre-cured by irradiating it with ultraviolet light (wavelength 365 nm) for 30 seconds. Then, it was heated at 120°C for 1 hour to perform full curing, and a liquid crystal element was produced. The sealant for liquid crystal elements obtained in Example 6 was cured by heating it at 120°C for 1 hour without irradiating it with ultraviolet light, and a liquid crystal element was produced. The obtained liquid crystal device was checked for liquid crystal alignment disorder (display unevenness) using a polarizing microscope (Keyence Corporation, "VHX-5000"), and the low liquid crystal contamination property was evaluated according to the following criteria. ◎: When no display irregularities were observed on the liquid crystal element ○: When slight unevenness in display is observed near the sticker pattern (periphery) △: Clear dark unevenness in the peripheral area ×: Clear, dark unevenness in the display is not limited to the periphery but extends to the center

[0068] [Table 1]

[0069] [Table 2]

[0070] [Table 3] [Industrial Applicability]

[0071] According to the present invention, it is possible to provide a sealant for liquid crystal elements that is excellent in storage stability, adhesiveness, and low liquid crystal contamination.

Claims

1. A composition comprising a curable resin, a thermosetting agent, and a (poly)alkylene glycol, the curable resin contains an epoxy compound, A sealant for liquid crystal elements, characterized in that the content of the (poly)alkylene glycol relative to 100 parts by mass of the curable resin is 0.1 parts by mass or more and 5 parts by mass or less.

2. 2. The sealant for liquid crystal elements according to claim 1, wherein the epoxy compound comprises a polyfunctional epoxy compound having two or more epoxy groups in one molecule, and the content of the (poly)alkylene glycol relative to 100 parts by mass of the polyfunctional epoxy compound is 0.5 parts by mass or more and 25 parts by mass or less.

3. 3. The sealant for liquid crystal elements according to claim 1, wherein the content of the (poly)alkylene glycol is 2.5 parts by mass or more and 125 parts by mass or less per 100 parts by mass of the heat curing agent.

4. 3. The sealant for liquid crystal devices according to claim 1, wherein the (poly)alkylene glycol contains diethylene glycol.

5. 3. The sealant for liquid crystal devices according to claim 1, wherein the heat curing agent comprises at least one selected from the group consisting of an imidazole adduct of an epoxy compound and an imidazole compound.

6. 3. The sealant for liquid crystal devices according to claim 1, further comprising a radical polymerization initiator.

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

8. 3. The sealant for liquid crystal devices according to claim 1, which is used in the production of liquid crystal devices by a liquid crystal dropping method.

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