Sealant for display elements and liquid crystal display element

Abstract

To provide a sealant for display elements that excels in storage stability and in curability and adhesiveness when cured at low temperature, and a liquid crystal display element formed using the sealant for display elements.SOLUTION: Provided is a sealant for display elements that contains a curable resin and a polymerization initiator. The curable resin contains an epoxy compound, an oxetane compound, and a (meth)acrylic compound. The oxetane compound contains a compound having at least one oxetanyl group and at least one hydroxyl group in one molecule, the polymerization initiator contains a cationic polymerization initiator and a radical polymerization initiator, and the sealant for display elements does not contain an amine thermosetting agent, or contains less than 3.0 mass% of the amine thermosetting agent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sealant for a display element, and also to a liquid crystal display element obtained by using the sealant for a display element. [Background technology]

[0002] In recent years, liquid crystal display elements and organic EL display elements have been widely used as display elements having characteristics such as thinness, light weight, low power consumption, etc. In such display elements, a sealant for display elements is usually used for bonding various members, sealing the liquid crystal and light-emitting layer, etc.

[0003] For example, liquid crystal display elements are manufactured by a method called a vacuum injection method or a liquid crystal dropping method. In the vacuum injection method, as disclosed in Patent Document 1, two electrode-attached substrates are placed facing each other at a predetermined interval, and the periphery is sealed with a sealant to form a cell, and liquid crystal is injected into the cell through a liquid crystal injection port provided in a part of the cell, and the liquid crystal injection port is sealed with a sealant (sealing agent), thereby manufacturing a liquid crystal display element. In the liquid crystal dropping method, as disclosed in Patent Documents 2 and 3, a frame-shaped seal pattern is first formed on one of the two electrode-attached substrates by dispensing. Next, while the sealant is not yet cured, minute droplets of liquid crystal are dropped into the seal frame of the substrate, and the other substrate is superimposed under vacuum to cure the sealant, thereby manufacturing a liquid crystal display element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-257444 A [Patent Document 2] JP 2001-133794 A [Patent Document 3] WO 02 / 092718 Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of activities that consider the environment, social, and governance (ESG activities) and from the viewpoint of dealing with substrates with low heat resistance, etc., it is desired to cure a sealant at a low temperature (for example, 80°C or lower). Conventionally, sealants containing an epoxy compound and an amine-based heat curing agent for curing the epoxy compound have been widely used. As a method for curing such sealants at low temperatures, it is possible to use a heat curing agent having a low reaction initiation temperature, but there are problems in that the sealant has poor storage stability and the cured product obtained by curing at low temperatures does not have sufficient adhesive strength.

[0006] The present invention aims to provide a sealant for display elements that has excellent storage stability, and excellent curability and adhesiveness when cured at low temperatures, and also aims to provide a liquid crystal display element using the sealant for display elements. [Means for solving the problem]

[0007] Disclosure 1 relates to a sealant for display elements, which contains a curable resin and a polymerization initiator, wherein the curable resin contains an epoxy compound, an oxetane compound, and a (meth)acrylic compound, the oxetane compound contains a compound having at least one oxetanyl group and at least one hydroxyl group in one molecule, the polymerization initiator contains a cationic polymerization initiator and a radical polymerization initiator, and the sealant for display elements does not contain an amine-based heat curing agent or contains less than 3.0 mass % of the amine-based heat curing agent. The present disclosure 2 is the sealant for display elements of the present disclosure 1, in which the content of the oxetane compound is 60 parts by mass or less with respect to 100 parts by mass of the epoxy compound. The present disclosure 3 is the sealant for display elements of the present disclosure 1 or 2, in which the content of the oxetane compound is 20 parts by mass or less based on 100 parts by mass of the (meth)acrylic compound. Disclosure 4 relates to a sealant for display elements according to Disclosure 1, 2 or 3, wherein the (meth)acrylic compound contains a compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule. The present disclosure 5 is a sealant for a display element according to the present disclosure 1, 2, 3 or 4, further comprising a filler. The present disclosure 6 is a sealant for display elements according to the present disclosure 1, 2, 3, 4 or 5, further comprising a silane coupling agent. The present disclosure 7 is a sealant for display elements according to the present disclosure 1, 2, 3, 4, 5 or 6, in which the reaction rate of the epoxy groups derived from the epoxy compound is 80% or more when the sealant for display elements is heated at 80° C. for 1 hour. The eighth disclosure is a liquid crystal display element including a cured product of the sealant for display elements according to the first, second, third, fourth, fifth, sixth or seventh disclosure. The present invention will be described in detail below.

[0008] The present inventors have investigated the use of a combination of an epoxy compound, an oxetane compound having a specific structure, and a (meth)acrylic compound as a curable resin, and a cationic polymerization initiator and a radical polymerization initiator as a polymerization initiator. As a result, they have found that it is possible to obtain a sealant for display elements that does not require an amine-based heat curing agent and that has excellent storage stability, and excellent curability and adhesiveness (especially adhesiveness to a substrate having an ITO electrode or an alignment film) when cured at a low temperature (e.g., 80°C or less), and thus have completed the present invention.

[0009] The sealant for a display element of the present invention contains a curable resin. The curable resin includes an epoxy compound, an oxetane compound, and a (meth)acrylic compound. 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), EPICLON850 (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. The partially (meth)acrylic modified epoxy compound is treated as the above epoxy compound, not as the (meth)acrylic compound described later. In this specification, the term "(meth)acryloyl" means acryloyl or methacryloyl.

[0013] Among the partially (meth)acrylic modified epoxy compounds, examples of commercially available compounds include UVACURE1561, KRM8030, KRM8287 (all manufactured by Daicel-Allnex Corporation), and the like.

[0014] The content of the epoxy compound in 100 parts by mass of the total curable resin is preferably 5 parts by mass at the lower limit and 50 parts by mass at the upper limit. By making the content of the epoxy compound within this range, the obtained sealant for display elements has better curability and adhesion, and when used as a sealant for liquid crystal display elements, it also has excellent low liquid crystal contamination. The content of the epoxy compound is more preferably 10 parts by mass at the lower limit and 30 parts by mass at the upper limit.

[0015] The oxetane compound includes a compound having at least one oxetanyl group and at least one hydroxyl group in one molecule. By containing the compound having at least one oxetanyl group and at least one hydroxyl group in one molecule in combination with a cationic polymerization initiator described below, the sealant for display elements of the present invention has excellent adhesiveness when cured at low temperature.

[0016] The compound having at least one oxetanyl group and at least one hydroxyl group in one molecule preferably has at least one hydroxyl group at an end of the main chain.

[0017] Specific examples of the compound having at least one oxetanyl group and at least one hydroxyl group in one molecule include 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(4-hydroxybutyloxymethyl)oxetane, 3-(prop-2-ynyl)oxetan-3-ol, (4,4-dimethyloxetan-2-yl)methanol, and trimethylolpropaneoxetane.

[0018] The preferred lower limit of the content of the oxetane compound in 100 parts by mass of the total curable resin is 0.1 parts by mass, and the preferred upper limit is 50 parts by mass. By having the content of the oxetane compound in this range, the resulting sealant for display elements has better adhesion when cured at low temperatures. The more preferred lower limit of the content of the oxetane compound is 1 part by mass, and the more preferred upper limit is 30 parts by mass. The content of the oxetane compound is preferably 60 parts by mass or less relative to 100 parts by mass of the epoxy compound. By making the content of the oxetane compound 60 parts by mass or less relative to 100 parts by mass of the epoxy compound, the resulting sealant for display elements has better adhesion when cured at low temperature. The more preferred upper limit of the content of the oxetane compound relative to 100 parts by mass of the epoxy compound is 30 parts by mass. The content of the oxetane compound is preferably 20 parts by mass or less relative to 100 parts by mass of the (meth)acrylic compound described below. When the content of the oxetane compound is 20 parts by mass or less relative to 100 parts by mass of the (meth)acrylic compound, the resulting sealant for display elements has excellent adhesion when cured at low temperature.

[0019] Examples of the (meth)acrylic compound include (meth)acrylic acid ester compounds, epoxy (meth)acrylates, and urethane (meth)acrylates. In this specification, the "(meth)acrylic compound" refers to a compound having a (meth)acryloyl group, excluding the partially (meth)acrylic-modified epoxy compound. The "(meth)acrylate" refers to an acrylate or methacrylate, and the "epoxy (meth)acrylate" refers to a compound in which all epoxy groups in an epoxy compound are 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, isomyristyl (meth)acrylate, and the like. (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, bicyclopentenyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxy Ethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethyl carbitol (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoroethylene glycol (meth)acrylate, Examples of the acrylates include fluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, imide (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, and glycidyl (meth)acrylate.

[0021] 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.

[0022] 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.

[0023] 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.

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

[0025] 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 RDX63182, and KRM8076. Examples of the epoxy (meth)acrylates manufactured by Shin-Nakamura Chemical Co., Ltd. include EA-1010, EA-1020, EA-5323, EA-5520, EA-CHD, and EMA-1020. Examples of the epoxy (meth)acrylates manufactured by Kyoeisha Chemical Co., Ltd. include Epoxy Ester M-600A, Epoxy Ester 40EM, Epoxy Ester 70PA, Epoxy Ester 200PA, Epoxy Ester 80MFA, Epoxy Ester 3002M, Epoxy Ester 3002A, Epoxy Ester 1600A, Epoxy Ester 3000M, Epoxy Ester 3000A, Epoxy Ester 200EA, and Epoxy Ester 400EA. Examples of the epoxy (meth)acrylates manufactured by Nagase ChemteX Corporation include Denacol Acrylate DA-141, Denacol Acrylate DA-314, and Denacol Acrylate DA-911.

[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 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.

[0028] 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.

[0029] Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl (meth)acrylates, mono(meth)acrylates of dihydric alcohols, mono(meth)acrylates or di(meth)acrylates of trihydric alcohols, and epoxy (meth)acrylates. Examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of the trihydric alcohol include trimethylolethane, trimethylolpropane, and glycerin. The epoxy (meth)acrylate may, for example, be bisphenol A type epoxy (meth)acrylate.

[0030] 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.

[0031] Among them, the (meth)acrylic compound preferably contains a hydrogen-bonding functional group to improve adhesion to the interface, more preferably contains a compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule, and particularly preferably contains 2-hydroxy-3-phenoxypropyl (meth)acrylate. The (meth)acrylic compound also preferably contains the epoxy (meth)acrylate, and more preferably contains a combination of the compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule and the epoxy (meth)acrylate.

[0032] The preferred lower limit of the content of the (meth)acrylic compound in 100 parts by mass of the total curable resin is 30 parts by mass, and the preferred upper limit is 90 parts by mass. By having the content of the (meth)acrylic compound in this range, the resulting sealant for display elements has better curability and adhesion, and when used as a sealant for liquid crystal display elements, it also has excellent low liquid crystal contamination. The more preferred lower limit of the content of the (meth)acrylic compound is 40 parts by mass, and the more preferred upper limit is 80 parts by mass.

[0033] The preferred lower limit of the total content of the curable resin in 100 parts by mass of the sealant for display elements of the present invention is 50 parts by mass, and the preferred upper limit is 95 parts by mass. By having the total content of the curable resin in this range, the resulting sealant for 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 85 parts by mass.

[0034] The sealing agent for display elements of the present invention contains a polymerization initiator. The polymerization initiator includes a cationic polymerization initiator and a radical polymerization initiator. As described above, by containing the compound having at least one oxetanyl group and at least one hydroxyl group in one molecule in combination with the cationic polymerization initiator, the sealant for display elements of the present invention has excellent adhesiveness when cured at low temperature.

[0035] The cationic polymerization initiator may be a photo-induced cationic polymerization initiator or a thermal cationic polymerization initiator.

[0036] The photocationic polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid upon irradiation with light, and may be an ionic photoacid generating type or a nonionic photoacid generating type.

[0037] The anion portion of the ionic photoacid generating cationic photopolymerization initiator may be, for example, BF 4 - , P.F. 6 - , SbF 6 - , (BX 4 ) - (wherein X represents a phenyl group substituted with at least two fluorine or trifluoromethyl groups). The anion moiety may be PF m (C n F 2n+1 ) 6-m - (wherein m is an integer of 0 or more and 5 or less, and n is an integer of 1 or more and 6 or less). Examples of the ionic photoacid generating type photocationic polymerization initiator include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe salts, and the like, each of which has the anion moiety.

[0038] Examples of the aromatic sulfonium salt include bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(diphenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(diphenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, diphenyl-4-(phenylthio)phenylsulfonium tetrakis(pentafluorophenyl)borate, and triphenylsulfonium hexafluorophosphate. Examples of the sulfonium tetrakis(pentafluorophenyl)borate include triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, and tris(4-(4-acetylphenyl)thiophenyl)sulfonium tetrakis(pentafluorophenyl)borate.

[0039] Examples of the aromatic iodonium salt include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluorophosphate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluoroantimonate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrafluoroborate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrakis(pentafluorophenyl)borate, and the like.

[0040] Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis(pentafluorophenyl)borate.

[0041] Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2-cyanopyridinium tetrakis(pentafluorophenyl)borate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluorophosphate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluoroantimonate, 1-(naphthylmethyl)-2-cyanopyridinium tetrafluoroborate, and 1-(naphthylmethyl)-2-cyanopyridinium tetrakis(pentafluorophenyl)borate.

[0042] Examples of the (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe salt include (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluorophosphate, (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluoroantimonate, (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) tetrafluoroborate, and (2,4-cyclopentadiene-1-yl)((1-methylethyl)benzene)-Fe(II) tetrakis(pentafluorophenyl)borate.

[0043] Examples of the nonionic photoacid generating cationic photopolymerization initiator include nitrobenzyl esters, sulfonic acid derivatives, phosphoric acid esters, phenolsulfonic acid esters, diazonaphthoquinones, and N-hydroxyimide sulfonates.

[0044] Among the above-mentioned photocationic polymerization initiators, commercially available ones include, for example, photocationic polymerization initiators manufactured by Midori Chemical Industry Co., Ltd., photocationic polymerization initiators manufactured by Union Carbide Corporation, photocationic polymerization initiators manufactured by ADEKA Corporation, photocationic polymerization initiators manufactured by 3M Corporation, photocationic polymerization initiators manufactured by BASF Corporation, photocationic polymerization initiators manufactured by Solvay Corporation, and photocationic polymerization initiators manufactured by San-Apro Corporation. An example of the photocationic polymerization initiator manufactured by Midori Kagaku Co., Ltd. is DTS-200. Examples of the photocationic polymerization initiator manufactured by Union Carbide include UVI6990 and UVI6974. Examples of the photocationic polymerization initiator manufactured by ADEKA Corporation include SP-150 and SP-170. Examples of the photocationic polymerization initiator manufactured by 3M include FC-508 and FC-512. Examples of the cationic photopolymerization initiator manufactured by BASF include IRGACURE261 and IRGACURE290. An example of the photocationic polymerization initiator manufactured by Solvay is PI2074. Examples of the photocationic polymerization initiators manufactured by San-Apro include CPI-100P, CPI-200K, CPI-210S, CPI-310FG, and CPI-410S.

[0045] The thermal cationic polymerization initiator has an anion moiety of BF 4 - , P.F. 6 - , SbF 6 - , or (BX 4 ) - (wherein X represents a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups), and the like. Of these, sulfonium salts and ammonium salts are preferred.

[0046] Examples of the sulfonium salt include triphenylsulfonium tetrafluoroborate and triphenylsulfonium hexafluoroantimonate.

[0047] Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantimonate and tetrabutylphosphonium hexafluoroantimonate.

[0048] Examples of the ammonium salt include dimethylphenyl(4-methoxybenzyl)ammonium hexafluorophosphate, dimethylphenyl(4-methoxybenzyl)ammonium hexafluoroantimonate, dimethylphenyl(4-methoxybenzyl)ammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(4-methylbenzyl)ammonium hexafluorophosphate, dimethylphenyl(4-methylbenzyl)ammonium hexafluoroantimonate, dimethylphenyl(4-methylbenzyl)ammonium hexafluorotetrakis(pentafluorophenyl)borate, and methylphenyldibenzylammonium hexafluorophosphate. , methylphenyldibenzylammonium hexafluoroantimonate, methylphenyldibenzylammonium tetrakis(pentafluorophenyl)borate, phenyltribenzylammonium tetrakis(pentafluorophenyl)borate, dimethylphenyl(3,4-dimethylbenzyl)ammonium tetrakis(pentafluorophenyl)borate, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-diethyl-N-benzylanilinium tetrafluoroborate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, and N,N-diethyl-N-benzylpyridinium trifluoromethanesulfonate.

[0049] The content of the cationic polymerization initiator is preferably 0.1 parts by mass at the lower limit and 5 parts by mass at the upper limit with respect to 100 parts by mass of the curable resin. By the content of the cationic polymerization initiator being within this range, the obtained sealant for display elements has excellent storage stability and curability when cured at low temperatures, and also has excellent low liquid crystal contamination when used as a sealant for liquid crystal display elements. The more preferred lower limit of the content of the cationic polymerization initiator is 0.5 parts by mass, and the more preferred upper limit is 3 parts by mass.

[0050] As the radical polymerization initiator, a photoradical polymerization initiator is preferably used. Examples of the photoradical polymerization initiator include benzophenone-based compounds, acetophenone-based compounds, acylphosphine oxide-based compounds, titanocene-based compounds, oxime ester-based compounds, benzoin ether-based compounds, and thioxanthone-based compounds. Specific examples of the photoradical polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4-(4-morpholinyl)phenyl)-1-butanone, 2,2-dimethoxy-1,2-diphenylethan-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl-1,2-diphenylethan-1-one ... ethyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 1-(4-(2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-(phenylthio)phenyl)-1,2-octanedione 2-(O-benzoyloxime), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and the like. The radical polymerization initiators may be used alone or in combination of two or more kinds.

[0051] The content of the radical polymerization initiator is preferably 0.1 parts by mass at the lower limit and 5 parts by mass at the upper limit with respect to 100 parts by mass of the curable resin. By the content of the radical polymerization initiator being within this range, the obtained sealant for display elements has better storage stability and curability. The more preferred lower limit of the content of the radical polymerization initiator is 0.5 parts by mass, and the more preferred upper limit is 3 parts by mass.

[0052] The sealant for display elements of the present invention does not contain an amine-based heat curing agent or contains less than 3.0 mass % of the amine-based heat curing agent. The sealant for display elements of the present invention does not require an amine-based heat curing agent, or even if it contains an amine-based heat curing agent, the content of the amine-based heat curing agent is extremely small, and the sealant has excellent storage stability, curability and adhesiveness when cured at low temperature. Examples of the amine-based heat curing agent include organic acid hydrazides, imidazole derivatives, and amine adduct compounds.

[0053] The sealant for display elements of the present invention preferably further contains a filler for the purposes of improving viscosity, further improving adhesion due to a stress dispersion effect, improving the linear expansion coefficient, and improving the moisture resistance of the cured product.

[0054] As the filler, an inorganic filler or an organic filler 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, (meth)acrylic polymer fine particles, etc. The organic filler may have a core-shell structure. The above fillers may be used alone or in combination of two or more kinds.

[0055] The preferred lower limit of the content of the filler relative to 100 parts by mass of the curable resin is 10 parts by mass, and the preferred upper limit is 40 parts by mass. By having the content of the filler within this range, the effect of improving adhesion and the like is excellent without deteriorating the coating properties and the like. The more preferred lower limit of the content of the filler is 20 parts by mass, and the more preferred upper limit is 30 parts by mass.

[0056] The sealant for 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 display elements and a substrate or the like.

[0057] Suitable examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-isocyanatopropyltrimethoxysilane. These have an excellent effect of improving adhesion to a substrate, etc., and when the resulting sealant for a display element is used as a sealant for a liquid crystal display element, it is possible to suppress outflow of the curable resin into the liquid crystal. The above silane coupling agents may be used alone or in combination of two or more kinds.

[0058] The content of the silane coupling agent is preferably 0.1 parts by mass and 5 parts by mass relative to 100 parts by mass of the curable resin. The content of the silane coupling agent is within this range, and the effect of improving adhesion is more excellent. The content of the silane coupling agent is more preferably 0.3 parts by mass and 2 parts by mass.

[0059] The sealant for display 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, if necessary.

[0060] The method for producing the sealant for display elements of the present invention can be, for example, a method in which a curable resin, a polymerization initiator, and additives such as a silane coupling agent, which are added as necessary, 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.

[0061] The above sealant for display elements has a reaction rate of 80% or more of the epoxy group derived from the above epoxy compound when heated at 80° C. for 1 hour. Since the reaction rate of the epoxy group is 80% or more, the above sealant for display elements can be suitably used in the manufacture of display elements having a sealant curing step at low temperatures. The reaction rate of the epoxy group is more preferably 85% or more, and most preferably 100%. The reaction rate of the epoxy group can be measured by the following method. That is, the above sealant for display elements was cured by heating at 80° C. for 1 hour, and the sealant for display elements before curing and the cured product were subjected to FT-IR analysis using a Fourier transform infrared spectrophotometer. -1 The rate of decrease in the peak of the above-mentioned compound can be calculated as the reaction rate of the epoxy group. Examples of the Fourier transform infrared spectrophotometer include Nicolet iS-5 (manufactured by ThermoFisher).

[0062] By blending conductive fine particles with the sealant for display elements of the present invention, a vertically conductive material can be produced.

[0063] 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.

[0064] The sealant for display elements of the present invention is preferably used as a sealant for liquid crystal display elements, and particularly, the sealant for display elements of the present invention is preferably used in the production of liquid crystal display elements by a vacuum injection method. A liquid crystal display element containing a cured product of the sealant for display elements of the present invention also constitutes the present invention.

[0065] The liquid crystal display element of the present invention is preferably a liquid crystal display element with a narrow frame design. Specifically, it is preferable that the width of the frame part surrounding the liquid crystal display part is 2 mm or less. When the liquid crystal display element of the present invention is produced, the application width of the sealant for a display element of the present invention is preferably 1 mm or less. Effect of the Invention

[0066] According to the present invention, it is possible to provide a sealant for a display element that has excellent storage stability, and excellent curability and adhesiveness when cured at a low temperature. Also, according to the present invention, it is possible to provide a liquid crystal display element using the sealant for a display element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0068] (Examples 1 to 12, Comparative Examples 1 to 9) According to the compounding ratios shown in Tables 1 and 2, each material was stirred with a planetary stirrer (Thinky Corporation, "Awatori Rentaro"), and then mixed uniformly with a ceramic triple roll to obtain display element sealants of Examples 1 to 12 and Comparative Examples 1 to 9. The obtained sealant for display elements was cured by heating at 80° C. for 1 hour. The sealant for display elements before curing and the cured product were subjected to FT-IR analysis using a Fourier transform infrared spectrophotometer. -1 The reduction rate of the peak was calculated as the reaction rate of the epoxy group. The Fourier transform infrared spectrophotometer used was a Nicolet iS-5 (manufactured by ThermoFisher). The results are shown in Tables 1 and 2.

[0069] <Evaluation> The following evaluations were carried out on each of the obtained sealants for display elements, and the results are shown in Tables 1 and 2.

[0070] (Curing properties when cured at low temperatures) The curability when cured at low temperature was evaluated by rating it as follows: if the reaction rate of the epoxy groups calculated by the above-mentioned method was 80% or more, it was marked as "○", and if it was less than 80%, it was marked as "×".

[0071] (Adhesion when cured at low temperature) One part by mass of spacer particles (manufactured by Sekisui Chemical Co., Ltd., "Micropearl SP-2050") having an average particle size of 5 μm was uniformly dispersed in 100 parts by mass of each of the obtained sealants for display elements using a planetary stirrer. A very small amount of the sealant for display elements with spacer particles dispersed therein was placed in the center of a glass substrate with an ITO thin film, and another glass substrate with an ITO thin film of the same type was placed on top of it. The sealant for display elements was spread and irradiated with 100 mW / cm using a metal halide lamp. 2 After irradiating with ultraviolet light for 30 seconds, the sealant for display elements was cured by heating at 80°C for 1 hour to obtain an adhesion test piece. Also, an adhesion test piece was obtained in the same manner, except that a substrate with an alignment film was used instead of the glass substrate with an ITO thin film. The substrate with the alignment film was prepared by applying an imide resin to the glass substrate with an ITO thin film by spin coating, pre-baking at 80°C, and then baking at 230°C. SE7492 (manufactured by Nissan Chemical Industries, Ltd.) was used as the imide resin. The adhesive strength of the obtained adhesion test piece was measured using a tension gauge. Adhesive strength: 2.5kgf / cm 2 If it is more than 2.0kgf / cm, mark it as "◎" 2 More than 2.5kgf / cm 2 If it is less than 1.0kgf / cm, it is marked as "○" 2 More than 2.0kgf / cm 2 If it is less than 1.0kgf / cm, it is marked as "△" 2If the measured value was less than this, it was marked as "X" and the adhesiveness when cured at a low temperature was evaluated.

[0072] (Storage stability) The initial viscosity of each of the obtained sealants for display elements immediately after production and the viscosity after storage for one week at 25° C. were measured. The viscosity increase ratio was defined as (viscosity after storage) / (initial viscosity), and the storage stability was evaluated by rating a viscosity increase ratio of less than 1.1 as "◎", a viscosity increase ratio of 1.1 or more and less than 2.0 as "◯", and a viscosity increase ratio of 2.0 or more as "×". The viscosity of the sealant for display elements was measured using an E-type viscometer (manufactured by BROOK FIELD, "DV-III") at 25° C. and a rotation speed of 1.0 rpm.

[0073] [Table 1]

[0074] [Table 2] [Industrial Applicability]

[0075] According to the present invention, it is possible to provide a sealant for a display element that has excellent storage stability, and excellent curability and adhesiveness when cured at a low temperature. Also, according to the present invention, it is possible to provide a liquid crystal display element using the sealant for a display element.

Claims

1. A sealant for a display element, comprising a curable resin and a polymerization initiator, the curable resin contains an epoxy compound, an oxetane compound, and a (meth)acrylic compound; The oxetane compound includes a compound having at least one oxetanyl group and at least one hydroxyl group in one molecule, The polymerization initiator includes a cationic polymerization initiator and a radical polymerization initiator, The sealant for display elements does not contain an amine-based heat curing agent or contains less than 3.0% by mass of the amine-based heat curing agent. A sealant for a display element.

2. 2. The sealant for display elements according to claim 1, wherein the content of the oxetane compound is 60 parts by mass or less based on 100 parts by mass of the epoxy compound.

3. 3. The sealant for display elements according to claim 1, wherein the content of the oxetane compound is 20 parts by mass or less based on 100 parts by mass of the (meth)acrylic compound.

4. 3. The sealant for display elements according to claim 1, wherein the (meth)acrylic compound includes a compound having one (meth)acryloyl group and at least one hydroxyl group in one molecule.

5. 3. The sealant for a display element according to claim 1, further comprising a filler.

6. 3. The sealant for display elements according to claim 1 or 2, further comprising a silane coupling agent.

7. 3. The sealant for display elements according to claim 1, wherein a reaction rate of the epoxy groups derived from the epoxy compound is 80% or more when the sealant for display elements is heated at 80° C. for 1 hour.

8. A liquid crystal display element comprising a cured product of the sealant for display elements according to claim 1 or 2.

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