Sealants for liquid crystal display elements and liquid crystal display elements

Abstract

The present invention aims to provide a sealant for liquid crystal display elements that exhibits excellent visible light curability and adhesion to alignment films, and enables the production of highly reliable liquid crystal display elements. Furthermore, the present invention aims to provide a liquid crystal display element manufactured using this sealant. The present invention relates to a sealant for liquid crystal display elements, comprising a curable resin and a photopolymerization initiator. The curable resin comprises a compound having an aromatic ring and a polymerizable functional group, wherein the aromatic ring comprises 50% or more of the compound. The photopolymerization initiator comprises a compound having one or more photopolymerization initiating groups and three or more heterocyclic rings per molecule. The difference in solubility parameter between the curable resin as a whole and the compound having one or more photopolymerization initiating groups and three or more heterocyclic rings per molecule is 2.0 or less.

Description

Technical Field

[0001] This invention relates to a sealant for liquid crystal display elements that exhibits excellent visible light curability and adhesion to alignment films, resulting in liquid crystal display elements with high reliability. Furthermore, this invention relates to liquid crystal display elements manufactured using this sealant. Background Technology

[0002] In recent years, as a manufacturing method for liquid crystal display elements such as liquid crystal display units, from the viewpoint of shortening production cycle time and optimizing the amount of liquid crystal used, a liquid crystal dropping process using a sealant, as disclosed in Patent Document 1 and Patent Document 2, has been adopted.

[0003] In the droplet process, firstly, a frame-shaped sealing pattern is formed on one of two electrode-bearing substrates using a dispensing method. Next, while the sealant is still uncured, tiny drops of liquid crystal are dropped into the sealing frame of the substrate. Then, the other substrate is overlapped under vacuum to cure the sealant, thus fabricating a liquid crystal display element. Currently, this droplet process is the mainstream method for manufacturing liquid crystal display elements.

[0004] However, with the widespread use of mobile devices with LCD panels, such as mobile phones and portable game consoles, miniaturization is a pressing issue. One method of miniaturization is to narrow the bezel of the LCD display, for example, by positioning the sealing portion under the black matrix (hereinafter also referred to as "narrow bezel design").

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2001-133794

[0008] Patent Document 2: International Publication No. 02 / 092718 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] With the development of narrow bezel designs, the distance from the pixel area to the sealant in liquid crystal display elements has become shorter, leading to more instances where the sealant is placed on the alignment film. Therefore, the sealant requires excellent adhesion to the alignment film.

[0011] Furthermore, while ultraviolet (UV) irradiation is commonly used to cure sealants, this method is particularly problematic in liquid crystal drop processes. Since the sealant is cured after the liquid crystal is dropped, UV irradiation can cause liquid crystal degradation. Therefore, to prevent UV-induced liquid crystal degradation, a method of curing the sealant by irradiation through a cutoff filter or similar material is employed. Consequently, sealants with excellent visible light curability are required.

[0012] The object of this invention is to provide a sealant for liquid crystal display elements that exhibits excellent visible light curability and adhesion to alignment films, and enables the production of liquid crystal display elements with excellent reliability. Furthermore, the object of this invention is to provide a liquid crystal display element manufactured using this sealant.

[0013] Methods for solving problems

[0014] This disclosure 1 is a sealant for liquid crystal display elements, comprising a curable resin and a photopolymerization initiator. The curable resin comprises a compound having an aromatic ring and a polymerizable functional group, wherein the aromatic ring comprises 50% or more of the compound. The photopolymerization initiator comprises a compound having one or more photopolymerization initiating groups and three or more heterocyclic rings in one molecule. The difference in solubility parameters between the curable resin as a whole and the compound having one or more photopolymerization initiating groups and three or more heterocyclic rings in one molecule is 2.0 or less.

[0015] This disclosure 2 relates to a sealant for liquid crystal display elements according to disclosure 1, wherein, in 100 parts by weight of the curable resin, the content of the compound having an aromatic ring and a polymerizable functional group, and wherein the aromatic ring contains 50% or more, is 15 parts by weight or more.

[0016] This disclosure 3 relates to a sealant for liquid crystal display elements of disclosure 1 or 2, wherein, in the compound having one or more photopolymerization initiating groups and three or more heterocycles in one molecule, at least one of the heterocycles is a thiophene ring.

[0017] This disclosure 4 relates to a sealant for liquid crystal display elements of disclosures 1, 2 or 3, wherein the glass transition temperature of the cured material is 85°C or higher.

[0018] This disclosure 5 is a liquid crystal display element that includes a cured product of the sealant for liquid crystal display elements of disclosures 1, 2, 3 or 4.

[0019] The present invention will now be described in detail.

[0020] In order to improve the adhesion of sealants for liquid crystal display elements to alignment films, the inventors investigated using compounds with a flexible backbone as curable resins. Furthermore, to improve visible light curability, they investigated using photopolymerization initiators with excellent reactivity to long-wavelength light. However, when increasing the amount of the compound with a flexible backbone to further improve adhesion to the alignment film, the visible light curability of the resulting sealant for liquid crystal display elements sometimes deteriorated. The inventors believed that the deterioration in visible light curability was due to the low compatibility between the curable resin containing the compound with a flexible backbone and the photopolymerization initiator. Therefore, the inventors investigated using compounds having aromatic rings and polymerizable functional groups, with the aromatic rings comprising 50% or more, as curable resins, and using compounds having one or more photopolymerization initiating groups and three or more heterocyclic rings per molecule as photopolymerization initiators. Based on this, they investigated setting the difference between the solubility parameter of the entire curable resin and the compound having one or more photopolymerization initiating groups and three or more heterocyclic rings per molecule to 2.0 or less. The results showed that a sealant for liquid crystal display elements with excellent visible light curability and adhesion to alignment films could be obtained, thus completing the present invention. Furthermore, the sealant for liquid crystal display elements of the present invention uses a compound containing 50% or more aromatic rings as a curing resin, thereby increasing the glass transition temperature of the cured product. Therefore, even when exposed to high temperature and high humidity environments, a liquid crystal display element with excellent reliability can be obtained.

[0021] The sealant for liquid crystal display elements of the present invention contains a curable resin.

[0022] The aforementioned curable resin comprises a compound having an aromatic ring and a polymerizable functional group, wherein the aromatic ring comprises 50% or more of the compound (hereinafter also referred to as "the curable resin of the present invention"). By combining the curable resin of the present invention with the photopolymerization initiator described later, the sealant for liquid crystal display elements of the present invention exhibits excellent visible light curability and adhesion to alignment films, and a liquid crystal display element with excellent reliability can be obtained.

[0023] The minimum content of aromatic rings in the curable resin of the present invention is 50%. Curable resins of the present invention containing 50% or more of these aromatic rings tend to have a skeleton similar to that of the alignment film. Therefore, by containing the curable resin of the present invention, the sealant for liquid crystal display elements of the present invention exhibits excellent adhesion to the alignment film. Furthermore, curable resins of the present invention containing 50% or more of these aromatic rings tend to have a rigid skeleton. Therefore, by containing the curable resin of the present invention, the glass transition temperature of the cured sealant for liquid crystal display elements of the present invention can be easily increased, resulting in a liquid crystal display element with excellent reliability. More preferably, the content of the aforementioned aromatic rings in the curable resin of the present invention is 55% or more.

[0024] Furthermore, the content of aromatic rings in the curable resin of the present invention does not have a preferred upper limit, but the practical upper limit is 75%.

[0025] It should be noted that, in this specification, the "content ratio of aromatic rings" refers to the ratio of the total molecular weight of the aromatic rings contained in one molecule of the compound to the molecular weight of one molecule of the compound. Furthermore, the "molecular weight of aromatic rings" refers to the total atomic weight of the carbon atoms constituting the aromatic rings. For example, in the case of the compound shown in formula (2-1) (molecular weight 492) described later, the molecular weight of one of the four aromatic rings is the sum of the atomic weights of six carbon atoms, i.e., 72, and the content ratio of aromatic rings is ((4 × 72) ÷ 492) × 100 = 59%.

[0026] The curable resin of the present invention preferably has three or more aromatic rings per molecule. By having the curable resin of the present invention have three or more aromatic rings per molecule, the adhesion of the sealant for liquid crystal display elements of the present invention to the alignment film is improved, and a liquid crystal display element with higher reliability can be obtained. Furthermore, from the viewpoint of coatability, the curable resin of the present invention preferably has six or fewer aromatic rings per molecule.

[0027] The aromatic rings of the curable resin of the present invention can be aromatic hydrocarbon rings or aromatic heterocycles.

[0028] The aromatic rings contained in the curable resin of the present invention include, for example, benzene rings, naphthalene rings, anthracene rings, furan rings, etc. Among them, benzene rings are preferred.

[0029] The curable resin of the present invention preferably has the structure shown in the following formulas (1-1) to (1-4) as a structure containing the above-mentioned aromatic ring.

[0030] [Chemical Formula 1]

[0031]

[0032] In equations (1-1) to (1-4), * indicates the bonding position.

[0033] Examples of polymerizable functional groups in the curable resin of the present invention include epoxy groups and (meth)acryloyl groups. Among these, epoxy groups are preferred.

[0034] It should be noted that in this specification, "(meth)acryloyl" refers to acryloyl or methacryloyl.

[0035] The preferred lower limit of the molecular weight of the curable resin of the present invention is 200, and the preferred upper limit is 2000. By making the molecular weight of the curable resin of the present invention 200 or higher, the low liquid crystal contamination property of the sealant for liquid crystal display elements of the present invention is improved. By making the molecular weight of the curable resin of the present invention 2000 or lower, the coatability of the sealant for liquid crystal display elements of the present invention is improved. The more preferred lower limit of the molecular weight of the curable resin of the present invention is 400, and the preferred upper limit is 800.

[0036] It should be noted that, in this specification, the "molecular weight" mentioned above refers to the molecular weight derived from the structural formula for compounds with specific molecular structures, but for compounds with a wide degree of polymerization and compounds with unspecified modification sites, the weight-average molecular weight is sometimes used.

[0037] Furthermore, in this specification, the aforementioned "weight-average molecular weight" is a value determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted from polystyrene. Examples of columns used for determining the weight-average molecular weight based on polystyrene conversion by GPC include the Shodex LF-804 (manufactured by Showa Denko Corporation).

[0038] Specifically, the preferred curable resins of the present invention are the compounds shown in formula (2-1) (containing 59% aromatic rings), the compounds shown in formula (2-2) (containing 58% aromatic rings), the compounds shown in formula (2-3) (containing 65% aromatic rings), and the compounds shown in formula (2-4) (containing 62% aromatic rings).

[0039] [Chemical Formula 2]

[0040]

[0041] The aforementioned curable resin may include other curable resins besides those of the present invention.

[0042] When the other curable resins mentioned above are included, the preferred lower limit for the content of the curable resin of the present invention in 100 parts by weight of the aforementioned curable resin is 15 parts by weight. By making the content of the curable resin of the present invention 15 parts by weight or more, the adhesion of the sealant for the liquid crystal display element to the alignment film becomes more excellent, and a liquid crystal display element with better reliability can be obtained. In addition, from the viewpoint of low liquid crystal contamination, the preferred upper limit for the content of the curable resin of the present invention is 50 parts by weight, and a more preferred upper limit is 30 parts by weight.

[0043] Other curable resins mentioned above include (meth)acrylic compounds other than those included in the curable resins of the present invention, epoxy compounds other than those included in the curable resins of the present invention, etc.

[0044] It should be noted that in this specification, "(meth)acrylic acid" refers to acrylic acid or methacrylic acid, and "(meth)acrylic acid compounds" refers to compounds having a (meth)acryloyl group.

[0045] Examples of (meth)acrylic compounds that can be used as other curable resins include (meth)acrylate compounds, epoxy (meth)acrylates, and urethane (meth)acrylates. Among these, epoxy (meth)acrylates are preferred. Furthermore, from a reactivity point of view, the above-mentioned (meth)acrylic compounds preferably have two or more (meth)acryloyl groups in one molecule.

[0046] It should be noted that in this specification, "(meth)acrylate" refers to acrylate or methacrylate. Furthermore, "epoxy (meth)acrylate" refers to a compound obtained by reacting all the epoxy groups in an epoxy compound with (meth)acrylic acid.

[0047] Examples of monofunctional compounds among the aforementioned (meth)acrylate compounds include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isononyl methacrylate, isodecanyl methacrylate, lauryl methacrylate, isomyristyl methacrylate, stearyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentenyl methacrylate, benzyl methacrylate, 2-methoxyethyl methacrylate, and 2-ethoxyethyl methacrylate. 2-Butoxyethyl methacrylate, 2-phenoxyethyl methacrylate, methoxyethylene glycol (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl methacrylate, ethyl carbitol (meth)acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 1H,1H,5H-octafluoropentyl methacrylate, imide (meth)acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, glycidyl methacrylate, etc.

[0048] Furthermore, examples of difunctional compounds among the aforementioned (meth)acrylate 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, and tripropylene glycol di(meth)acrylate. Ester, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide addition bisphenol A di(meth)acrylate, propylene oxide addition bisphenol A di(meth)acrylate, ethylene oxide addition bisphenol F di(meth)acrylate, dihydroxymethyldicyclopentadienyl di(meth)acrylate, ethylene oxide modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl(meth)acrylate, carbonate glycol di(meth)acrylate, polyether glycol di(meth)acrylate, polyester glycol di(meth)acrylate, polycaprolactone glycol di(meth)acrylate, polybutadiene glycol di(meth)acrylate, etc.

[0049] In addition, examples of compounds with three or more functions among the aforementioned (meth)acrylate compounds include: trimethylolpropane tri(meth)acrylate, ethylene oxide addition trimethylolpropane tri(meth)acrylate, propylene oxide addition trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, ethylene oxide addition isocyanuric acid tri(meth)acrylate, glycerol tri(meth)acrylate, propylene oxide addition glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tri(meth)acryloyloxyethyl phosphate, bis(trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc.

[0050] Examples of the aforementioned epoxy (meth)acrylates include epoxy (meth)acrylates obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a basic catalyst using conventional methods.

[0051] Examples of epoxy compounds that can be used as raw materials for the synthesis of the aforementioned epoxy (meth)acrylates include: bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, 2,2'-diallylbisphenol A type epoxy compounds, hydrogenated bisphenol type epoxy compounds, propylene oxide addition bisphenol A type epoxy compounds, resorcinol type epoxy compounds, biphenyl type epoxy compounds, thioether type epoxy compounds, and diphenyl ether type epoxy compounds. Compounds, including dicyclopentadiene-type epoxy compounds, naphthalene-type epoxy compounds, phenol-aldehyde-type epoxy compounds, o-cresol-aldehyde-type epoxy compounds, dicyclopentadiene-aldehyde-type epoxy compounds, biphenyl-aldehyde-type epoxy compounds, naphthalene-phenol-aldehyde-type epoxy compounds, glycidylamine-type epoxy compounds, alkyl polyol-type epoxy compounds, rubber-modified epoxy compounds, glycidyl ester compounds, etc.

[0052] Commercially available examples of the aforementioned bisphenol A type epoxy compounds include jER828EL, jER1004 (both manufactured by Mitsubishi Chemical Corporation), and EPICLON EXA-850CRP (manufactured by DIC Corporation).

[0053] Commercially available examples of the aforementioned bisphenol F type epoxy compounds include, for example, jER806 and jER4004 (both manufactured by Mitsubishi Chemical Corporation).

[0054] Commercially available examples of the aforementioned bisphenol S-type epoxy compounds include, for example, EPICLON EXA1514 (manufactured by DIC).

[0055] Commercially available examples of the aforementioned 2,2'-diallylbisphenol A type epoxy compounds include, for example, RE-810NM (manufactured by Nippon Kayaku Co., Ltd.).

[0056] Commercially available examples of the aforementioned hydrogenated bisphenol type epoxy compounds include, for example, EPICLON EXA7015 (manufactured by DIC).

[0057] Commercially available examples of the aforementioned propylene oxide addition bisphenol A type epoxy compounds include, for example, EP-4000S (manufactured by ADEKA).

[0058] Commercially available examples of the aforementioned resorcinol-type epoxy compounds include, for example, EX-201 (manufactured by Nagase ChemteX).

[0059] Commercially available examples of the aforementioned biphenyl-type epoxy compounds include, for example, jER YX-4000H (manufactured by Mitsubishi Chemical Corporation).

[0060] Commercially available examples of the aforementioned thioether-type epoxy compounds include YSLV-50TE (manufactured by NIPPON STEELC Chemical & Material Co., Ltd.).

[0061] Commercially available examples of the aforementioned diphenyl ether type epoxy compounds include YSLV-80DE (manufactured by NIPPONSTEEL Chemical & Material Co., Ltd.).

[0062] Commercially available examples of the aforementioned dicyclopentadiene-type epoxy compounds include, for example, EP-4088S (manufactured by ADEKA).

[0063] Commercially available examples of the aforementioned naphthalene-type epoxy compounds include EPICLON HP4032 and EPICLONEXA-4700 (both manufactured by DIC).

[0064] Commercially available examples of the aforementioned phenolic aldehyde type epoxy compounds include, for example, EPICLON N-770 (manufactured by DIC).

[0065] Commercially available examples of the aforementioned o-cresol phenolic epoxy compounds include, for example, EPICLON N-670-EXP-S (manufactured by DIC).

[0066] Commercially available examples of the aforementioned dicyclopentadiene phenolic epoxy compounds include, for example, EPICLON HP7200 (manufactured by DIC).

[0067] Commercially available examples of the aforementioned biphenyl phenolic epoxide compounds include NC-3000P (manufactured by Nippon Kayaku Co., Ltd.).

[0068] Commercially available examples of the aforementioned naphthol phenolic epoxide compounds include, for example, ESN-165S (manufactured by NIPPONSTEEL Chemical & Material).

[0069] Commercially available examples of the aforementioned glycidylamine type epoxy compounds include jER630 (manufactured by Mitsubishi Chemical Corporation), EPICLON 430 (manufactured by DIC Corporation), and TETRAD-X (manufactured by Mitsubishi Gas Chemical Corporation).

[0070] Commercially available examples of the aforementioned alkyl polyol type epoxy compounds include ZX-1542 (manufactured by NIPPONSTEEL Chemical & Material), EPICLON 726 (manufactured by DIC), EPOLIGHT 80MFA (manufactured by Kyoei Chemical Co., Ltd.), and Denacol EX-611 (manufactured by Nagase ChemteX).

[0071] Commercially available examples of the aforementioned rubber-modified epoxy compounds include YR-450, YR-207 (both manufactured by NIPPON STEEL Chemical & Material), and Epolead PB (manufactured by Daicel).

[0072] Commercially available examples of the aforementioned glycidyl ester compounds include, for example, Denacol EX-147 (manufactured by Nagase ChemteX).

[0073] Other commercially available epoxy compounds mentioned above include YDC-1312, YSLV-80XY, YSLV-90CR (all manufactured by NIPPON STEEL Chemical & Material), XAC4151 (manufactured by Asahi Kasei Corporation), jER1031, jER1032 (both manufactured by Mitsubishi Chemical Corporation), EXA-7120 (manufactured by DIC Corporation), and TEPIC (manufactured by Nissan Chemical Corporation).

[0074] Commercially available examples of the aforementioned epoxy (meth)acrylates include: epoxy (meth)acrylates manufactured by DAICL-ALLNEX, epoxy (meth)acrylates manufactured by Shin-Nakamura Chemical Industry Co., Ltd., epoxy (meth)acrylates manufactured by Kyoeisha Chemical Co., Ltd., epoxy (meth)acrylates manufactured by Nagase ChemteX, and epoxy (meth)acrylates manufactured by KSM.

[0075] Examples of epoxy (meth)acrylates manufactured by DAICL-ALLNEX include: EBECRYL 860, EBECRYL 3200, EBECRYL 3201, EBECRYL 3412, EBECRYL 3600, EBECRYL 3700, EBECRYL 3701, EBECRYL 3702, EBECRYL 3703, EBECRYL 3708, EBECRYL 3800, EBECRYL 6040, EBECRYL 8342, EBECRYL RDX 63182, KRM 8416, etc.

[0076] Examples of epoxy (meth)acrylates manufactured by Shin-Nakamura Chemical Industry Co., Ltd. include EA-1010, EA-1020, EA-5323, EA-5520, EA-CHD, and EMA-1020.

[0077] Examples of epoxy (meth)acrylates manufactured by Kyoei Chemical Co., Ltd. include: Epoxy Ester M-600A, Epoxy Ester 40EM, Epoxy Ester 70PA, Epoxy Ester 200PA, Epoxy Ester 80MFA, Epoxy Ester 3002M, Epoxy Ester 3002A, Epoxy Ester 1600A, Epoxy Ester 3000M, Epoxy Ester 3000A, Epoxy Ester 200EA, Epoxy Ester 400EA, etc.

[0078] Examples of epoxy (meth)acrylates manufactured by Nagase ChemteX include Denacol Acrylate DA-141, Denacol Acrylate DA-314, and Denacol Acrylate DA-911.

[0079] Examples of epoxy (meth)acrylates manufactured by KSM Corporation include, for example, BAEM-100.

[0080] The aforementioned urethane (meth)acrylates can be obtained, for example, by reacting a hydroxyl-containing (meth)acrylate derivative with a polyfunctional isocyanate compound in the presence of a catalytic amount of a tin-based compound.

[0081] Examples of the aforementioned polyfunctional isocyanate compounds include: isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornene diisocyanate, dimethylbiphenyl diisocyanate, phenylenediamine diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tri(isocyanate phenyl)thiophosphate (Japanese: トリス(イソシアネートフェニル)チオフォスフェート), tetramethylphenylenediamine diisocyanate, and 1,6,11-undecane triisocyanate.

[0082] Alternatively, as the aforementioned polyfunctional isocyanate compound, an extended-chain polyfunctional isocyanate compound obtained by reacting a polyol with an excess of the polyfunctional isocyanate compound can also be used.

[0083] Examples of such polyols include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate glycol, polyether glycol, polyester glycol, and polycaprolactone glycol.

[0084] Examples of the above-mentioned (meth)acrylic acid derivatives having hydroxyl groups include hydroxyalkyl mono(meth)acrylates, mono(meth)acrylates of diols, mono(meth)acrylates or di(meth)acrylates of triols, epoxy (meth)acrylates, etc.

[0085] Examples of the above-mentioned mono(meth)acrylate hydroxyalkyl esters include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate.

[0086] Examples of the aforementioned diols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol.

[0087] Examples of the aforementioned triols include trimethylolethane, trimethylolpropane, and glycerol.

[0088] Examples of the aforementioned epoxy (meth)acrylates include bisphenol A type epoxy (meth)acrylates.

[0089] Commercially available products among the aforementioned urethane (meth)acrylates include, for example, urethane (meth)acrylates manufactured by Toa Synthetic Co., Ltd., urethane (meth)acrylates manufactured by DAICL-ALLNEX Co., Ltd., urethane (meth)acrylates manufactured by Negami Kogyo Co., Ltd., urethane (meth)acrylates manufactured by Shin-Nakamura Chemical Co., Ltd., and urethane (meth)acrylates manufactured by Kyoeisha Chemical Co., Ltd.

[0090] Examples of urethane (meth) acrylates manufactured by the aforementioned Dong-A Synthetic Co., Ltd. include M-1100, M-1200, M-1210, and M-1600.

[0091] Examples of 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.

[0092] Examples of urethane (meth)acrylates manufactured by the aforementioned Nekami Kogyo Co., Ltd. include Artresin UN-330, Artresin SH-500B, Artresin UN-1200TPK, Artresin UN-1255, Artresin UN-3320HB, Artresin UN-7100, Artresin UN-9000A, and Artresin UN-9000H.

[0093] Examples of urethane (meth)acrylates manufactured by Shin-Nakamura Chemical Industry 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.

[0094] Examples of 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.

[0095] Examples of epoxy compounds that can be used as other curable resins mentioned above include epoxy compounds that serve as raw materials for the synthesis of the aforementioned epoxy (meth)acrylates, and partially (meth)acrylate-modified epoxy compounds.

[0096] It should be noted that, in this specification, the aforementioned (meth)acrylic acid modified epoxy compound refers to, for example, a compound having one or more epoxy groups and one (meth)acryloyl group in one molecule, obtained by reacting a portion of the epoxy groups of an epoxy compound having two or more epoxy groups in one molecule with (meth)acrylic acid.

[0097] From the viewpoint of making the sealant for the obtained liquid crystal display element have better low liquid crystal contamination, the other curable resins mentioned above preferably have units with hydrogen bonding such as -OH group, -NH- group, and -NH2 group.

[0098] The ratio of (meth)acryloyl groups in the total (meth)acryloyl groups and epoxy groups in the above-mentioned curable resin is preferably 30 mol% or more and 95 mol% or less. By keeping the ratio of (meth)acryloyl groups within this range, the resulting liquid crystal display element sealant suppresses the occurrence of liquid crystal contamination and improves adhesion.

[0099] The sealant for liquid crystal display elements of the present invention contains a photopolymerization initiator.

[0100] The aforementioned photopolymerization initiator comprises a compound having one or more photopolymerization initiating groups and three or more heterocyclic rings in one molecule (hereinafter also referred to as "the photopolymerization initiator of the present invention"). By combining the photopolymerization initiator of the present invention with the curable resin of the present invention, the sealant for liquid crystal display elements of the present invention exhibits excellent visible light curability and adhesion to alignment films, and a liquid crystal display element with excellent reliability can be obtained.

[0101] The photopolymerization initiator of the present invention has one or more photopolymerization initiation groups in one molecule.

[0102] It should be noted that, in this specification, the "photopolymerization initiating group" refers to a group that generates free radicals through hydrogen abstraction, cleavage, etc., by light irradiation, thereby promoting the polymerization reaction of the aforementioned curable resin.

[0103] Examples of photopolymerization initiating groups include oxime esters and thioxanone groups. Among these, oxime esters are preferred.

[0104] The photopolymerization initiator of the present invention has more than three heterocycles in one molecule.

[0105] The photopolymerization initiator of the present invention preferably has three or more heterocycles in one molecule. Furthermore, there is no preferred upper limit to the number of heterocycles in one molecule of the photopolymerization initiator of the present invention; the practical upper limit is five or less.

[0106] The heterocycle in the photopolymerization initiator of the present invention is preferably an aromatic heterocycle.

[0107] Examples of aromatic heterocycles include thiophene rings, furan rings, pyridine rings, and carbazole rings.

[0108] In addition, among the heterocycles in the photopolymerization initiator of the present invention, at least one is preferably a thiophene ring.

[0109] As the photopolymerization initiator of the present invention, the compound shown in the following formula (3) is preferred from the perspective that the resulting sealant for liquid crystal display elements has better adhesion to the alignment film, visible light curability and low liquid crystal contamination.

[0110] [Chemical Formula 3]

[0111]

[0112] In equation (3), R 1 Each of the following groups can be an alkyl, cycloalkyl, aralkyl, heterocyclic, or aryl group with 1 to 20 carbon atoms, which may have ether or amide bonds. The alkyl, cycloalkyl, aralkyl, heterocyclic, and aryl groups with 1 to 20 carbon atoms may have polar groups. In formula (3), R... 2 Each of the following groups can be an alkyl, cycloalkyl, aralkyl, heterocyclic, or aryl group with 1 to 20 carbon atoms, which may have ether or amide bonds. The alkyl, cycloalkyl, aralkyl, heterocyclic, and aryl groups with 1 to 20 carbon atoms may have polar groups. In formula (3), R... 3 Each of the following groups can be an alkyl, cycloalkyl, aralkyl, heterocyclic, or aryl group with 1 to 20 carbon atoms, which may have ether or amide bonds. The alkyl, cycloalkyl, aralkyl, heterocyclic, and aryl groups with 1 to 20 carbon atoms may have polar groups. In formula (3), R... 4 It has a structure containing a heteroaryl group.

[0113] In equation (3) above, R 1 Each of the following can be an alkyl, cycloalkyl, aralkyl, heterocyclic, or aryl group having 1 to 20 carbon atoms and may have ether or amide bonds. The alkyl, cycloalkyl, aralkyl, heterocyclic, and aryl groups having 1 to 20 carbon atoms may have polar groups.

[0114] In the above R 1 When the alkyl group has 1 to 20 carbon atoms, methyl or ethyl is preferred.

[0115] In the above R 1 In the case of a cycloalkyl group, examples of such cycloalkyl groups include cyclohexyl, cyclobutyl, etc.

[0116] In the above R 1 In the case of an aralkyl group, examples of such aralkyl groups include phenylmethyl, 2-naphthylmethyl, etc.

[0117] In the above R 1 In the case of a heterocyclic group, examples of such a heterocyclic group include 2-benzofuranyl.

[0118] In the above R 1 When the aryl group is aryl, examples of such aryl groups include phenyl and 1-naphthyl. Among these, phenyl is preferred.

[0119] Examples of polar groups include hydroxyl, carboxyl, and amino groups. Among these, the carboxyl group is preferred.

[0120] In equation (3) above, R 2 Each of the following can be an alkyl, cycloalkyl, aralkyl, heterocyclic, or aryl group having 1 to 20 carbon atoms and may have ether or amide bonds. The alkyl, cycloalkyl, aralkyl, heterocyclic, and aryl groups having 1 to 20 carbon atoms may have polar groups.

[0121] In the above R 2 When the alkyl group is alkyl, examples of such alkyl groups include methyl, ethyl, propyl, butyl, pentyl, and 2-ethylhexyl. Among these, methyl, ethyl, propyl, butyl, and pentyl are preferred.

[0122] In the above R 2 In the case of a cycloalkyl group, examples of such cycloalkyl groups include cyclopentyl and cyclohexyl. The aforementioned cycloalkyl groups may contain alkyl groups.

[0123] In the above R 2 In the case of an aralkyl group, examples of such aralkyl groups include phenylmethyl.

[0124] In the above R 2 In the case of a heterocyclic group, examples of such a heterocyclic group include 2-benzothiophene group.

[0125] In the above R 2 In the case of an aryl group, examples of such aryl groups include phenyl groups.

[0126] Examples of polar groups include hydroxyl, carboxyl, and amino groups. Among these, the carboxyl group is preferred.

[0127] In the above R 2 In the case of an alkyl group having a polar group, examples of such alkyl groups include carboxymethyl and 2-carboxyethyl.

[0128] In the above R 2In the case of a cycloalkyl group having a polar group, examples of such a cycloalkyl group include 2-carboxycyclohexyl and 2-carboxy-4-methylcyclohexyl.

[0129] In equation (3) above, R 3 Each of the following can be an alkyl, cycloalkyl, aralkyl, heterocyclic, or aryl group having 1 to 20 carbon atoms and may have ether or amide bonds. The alkyl, cycloalkyl, aralkyl, heterocyclic, and aryl groups having 1 to 20 carbon atoms may have polar groups.

[0130] In the above R 3 When the alkyl group is alkyl, examples of such alkyl groups include methyl, ethyl, propyl, butyl, pentyl, and 2-ethylhexyl. Among these, methyl, ethyl, propyl, butyl, and pentyl are preferred. The aforementioned alkyl groups may contain aryl groups.

[0131] In the above R 3 In the case of a cycloalkyl group, examples of such cycloalkyl groups include cyclohexyl groups.

[0132] In the above R 3 In the case of an aralkyl group, examples of such aralkyl groups include 2-naphthylmethyl.

[0133] In the above R 3 In the case of a heterocyclic group, examples of such heterocyclic groups include 2-thienyl group.

[0134] In the above R 3 In the case of an aryl group, examples of such aryl groups include phenyl groups. Examples of such polar groups include hydroxyl, carboxyl, and amino groups. Among these, carboxyl groups are preferred.

[0135] In the above R 3 In the case of an alkyl group having a polar group, examples of such alkyl groups include 1-carboxyethyl, 2-carboxyethyl, 1-carboxypropyl, 3-carboxypropyl, 1-carboxypentyl, and carboxy(phenyl)methyl.

[0136] In equation (3) above, R 4 It has a structure containing a heteroaryl group.

[0137] As mentioned above, R 4 Examples of heteroaryl groups shown include thienyl, furanyl, and pyridyl. Among these, thienyl is preferred.

[0138] Specifically, as the structure having a heteroaryl group mentioned above, the structures shown in formulas (4-1) to (4-6) below can be cited as examples.

[0139] [Chemical Formula 4]

[0140]

[0141] In equations (4-1) to (4-6), * indicates the bonding position.

[0142] As the photopolymerization initiator of the present invention, the compounds shown in the following formulas (5-1) to (5-3) are more preferred.

[0143] [Chemical Formula 5]

[0144]

[0145] The preferred lower limit for the content of the photopolymerization initiator of the present invention relative to 100 parts by weight of the curable resin is 0.01 parts by weight, and the preferred upper limit is 5 parts by weight. By making the content of the photopolymerization initiator of the present invention 0.01 parts by weight or more, the visible light curability of the resulting sealant for liquid crystal display elements becomes more excellent. By making the content of the photopolymerization initiator of the present invention 5 parts by weight or less, the low liquid crystal contamination of the resulting sealant for liquid crystal display elements becomes more excellent. The more preferred lower limit for the content of the photopolymerization initiator of the present invention is 0.1 parts by weight, and the more preferred upper limit is 2 parts by weight.

[0146] The difference in solubility parameter (SP value) between the curable resin and the photopolymerization initiator of the present invention is 2.0 or less. By ensuring that the difference in SP value between the curable resin and the photopolymerization initiator of the present invention is 2.0 or less, the compatibility between the curable resin and the photopolymerization initiator of the present invention becomes excellent, allowing for a low content of the photopolymerization initiator. As a result, the visible light curability of the sealant for liquid crystal display elements of the present invention becomes excellent. The difference in SP value between the curable resin and the photopolymerization initiator of the present invention is preferably 1.5 or less, more preferably 1.0 or less, and most preferably 0.

[0147] It should be noted that, in this specification, the SP value mentioned above is the Hansen solubility parameter, which can be derived from the structural formula using HSP software. The HSP software mentioned above can be Hansen Solubility Parameter in Practice (HSPiP). Furthermore, the overall SP value of the curing resin refers to the average SP value based on the weight fraction of each component of the curing resin.

[0148] The sealant for liquid crystal display elements of the present invention may contain a sensitizer, but from the viewpoint of low liquid crystal contamination, it is preferable not to contain the aforementioned sensitizer. The sealant for liquid crystal display elements of the present invention, by containing the photopolymerization initiator of the present invention, exhibits excellent visible light curability even without containing a sensitizer.

[0149] Examples of sensitizers mentioned above include ethyl 4-(dimethylamino)benzoate, 9,10-dibutoxyanthracene, 2,4-diethylthioxanthone, 2,2-dimethoxy-1,2-diphenylethane-1-one, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide.

[0150] Relative to 100 parts by weight of the curable resin, the preferred lower limit of the content of the sensitizer when containing the sensitizer is 0.01 parts by weight, and the preferred upper limit is 3 parts by weight. By ensuring the content of the sensitizer is 0.01 parts by weight or more, the sensitizing effect is further enhanced. By ensuring the content of the sensitizer is 3 parts by weight or less, light can be transmitted to deeper regions without excessive absorption. A more preferred lower limit of the content of the sensitizer is 0.1 parts by weight, and a more preferred upper limit is 1 part by weight.

[0151] The sealant for liquid crystal display elements of the present invention may contain a thermal polymerization initiator to a extent that does not impair the purpose of the present invention.

[0152] Examples of thermal polymerization initiators include those containing azo compounds, organic peroxides, etc. Among these, polymeric azo initiators containing high molecular weight azo compounds are preferred.

[0153] The above-mentioned thermal polymerization initiators can be used alone or in combination of two or more.

[0154] It should be noted that, in this specification, the term "high molecular weight azo compound" refers to a compound having an azo group and generating a free radical capable of curing (meth)acryloyloxy through heating, with a number average molecular weight of 300 or more.

[0155] Furthermore, in this specification, the "number-average molecular weight" mentioned above is a value obtained by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted from polystyrene. Examples of columns used for determining the number-average molecular weight based on polystyrene conversion by GPC include the Shodex LF-804 (manufactured by Showa Denko Corporation).

[0156] The preferred lower limit for the number-average molecular weight of the aforementioned azo polymer is 1000, and the preferred upper limit is 300,000. By ensuring that the number-average molecular weight of the aforementioned azo polymer is within this range, liquid crystal contamination can be suppressed, and it can be easily mixed with the curable resin. A more preferred lower limit for the number-average molecular weight of the aforementioned azo polymer is 5000, a more preferred upper limit is 100,000, a further preferred lower limit is 10,000, and a further preferred upper limit is 90,000.

[0157] Examples of such polymeric azo compounds include polymeric azo compounds having a structure in which multiple polyepoxide, polydimethylsiloxane, or other units are bonded together via azo groups.

[0158] As for the aforementioned polymeric azo compound having a structure in which multiple polyoxyalkylene units are bonded together via azo groups, a polymeric azo compound having a polyoxyethylene structure is preferred.

[0159] Specifically, examples of the aforementioned high molecular weight azo compounds include: condensation polymers of 4,4'-azobis(4-cyanovaleric acid) and polyalkylene glycols, and condensation polymers of 4,4'-azobis(4-cyanovaleric acid) and polydimethylsiloxanes having terminal amino groups.

[0160] Commercially available examples of the aforementioned high molecular weight azo compounds include VPE-0201, VPE-0401, VPE-0601, VPS-0501, and VPS-1001 (all manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.).

[0161] In addition, azo compounds that are not high molecular weight include, for example, V-65 and V-501 (both manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.).

[0162] Examples of the aforementioned organic peroxides include peroxide ketones, peroxide ketals, hydrogen peroxide, dialkyl peroxides, peroxide esters, diacyl peroxides, and peroxydicarbonates.

[0163] The preferred lower limit for the content of the thermal polymerization initiator relative to 100 parts by weight of the curable resin is 0.05 parts by weight, and the preferred upper limit is 10 parts by weight. By making the content of the thermal polymerization initiator 0.05 parts by weight or more, the thermosetting properties of the sealant for liquid crystal display elements of the present invention are improved. By making the content of the thermal polymerization initiator 10 parts by weight or less, the storage stability and low liquid crystal contamination of the sealant for liquid crystal display elements of the present invention are improved. The more preferred lower limit for the content of the thermal polymerization initiator is 0.1 parts by weight, and the more preferred upper limit is 5 parts by weight.

[0164] The sealant for liquid crystal display elements of the present invention preferably contains a thermosetting agent.

[0165] Examples of thermosetting agents include organic acid hydrazides, imidazole derivatives, amine compounds, polyphenolic compounds, and acid anhydrides. Among these, organic acid hydrazides are particularly suitable.

[0166] The above-mentioned thermosetting agents can be used alone or in combination of two or more.

[0167] Examples of the aforementioned organic acid hydrazides include sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, malonic acid dihydrazide, etc.

[0168] Commercially available examples of the aforementioned organic acid hydrazides include those manufactured by Otsuka Chemical Co., Ltd., and those manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0169] Examples of organic acid hydrazides manufactured by Otsuka Chemical Co., Ltd. include SDH, ADH, and MDH.

[0170] Examples of organic acid hydrazides manufactured by Ajinomoto Fine-Techno include Ajicure VDH, Ajicure VDH-J, Ajicure UDH, and Ajicure UDH-J.

[0171] The preferred lower limit for the content of the thermosetting agent relative to 100 parts by weight of the curable resin is 1 part by weight, and the preferred upper limit is 50 parts by weight. By keeping the content of the thermosetting agent within this range, the thermosetting properties can be improved without deteriorating the coatability, etc., of the resulting sealant for liquid crystal display elements. A more preferred upper limit for the content of the thermosetting agent is 30 parts by weight.

[0172] The sealant for liquid crystal display elements of the present invention preferably contains fillers for purposes such as increasing viscosity, improving adhesion based on stress dispersion effect, and improving coefficient of linear expansion.

[0173] Inorganic fillers or organic fillers can be used as the fillers mentioned above.

[0174] Examples of inorganic fillers mentioned above include silica, talc, glass beads, asbestos, gypsum, diatomaceous earth, chlorophyll, 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.

[0175] Examples of organic fillers mentioned above include polyester microparticles, polyurethane microparticles, vinyl polymer microparticles, and acrylic polymer microparticles.

[0176] The above fillers can be used alone or in combination of two or more.

[0177] The preferred lower limit for the content of the filler relative to 100 parts by weight of the curable resin is 30 parts by weight, and the preferred upper limit is 80 parts by weight. By keeping the content of the filler within this range, the effects of improving adhesion are made more superior without deteriorating coatability. The more preferred lower limit for the content of the filler is 45 parts by weight, and the more preferred upper limit is 65 parts by weight.

[0178] The sealant for liquid crystal display elements of the present invention preferably contains a silane coupling agent. The aforementioned silane coupling agent primarily functions as an adhesive aid for effectively bonding the sealant for liquid crystal display elements to a substrate or similar material.

[0179] As the aforementioned silane coupling agents, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, and 3-isocyanate-propyltrimethoxysilane are suitable examples. They excel in improving adhesion to substrates and the like, and by chemically bonding with the curable resin, they can suppress the outflow of the curable resin into the liquid crystal.

[0180] The above-mentioned silane coupling agents can be used alone or in combination of two or more.

[0181] The preferred lower limit of the content of the silane coupling agent in 100 parts by weight of the sealant for liquid crystal display elements of the present invention is 0.1 parts by weight, and the preferred upper limit is 10 parts by weight. By keeping the content of the silane coupling agent within this range, the resulting sealant for liquid crystal display elements suppresses the occurrence of liquid crystal contamination and improves adhesion. A more preferred lower limit of the content of the silane coupling agent is 0.3 parts by weight, and a more preferred upper limit is 5 parts by weight.

[0182] The sealant for liquid crystal display elements of the present invention may further contain additives such as reactive diluents, thixotropic agents, spacers, curing accelerators, defoamers, leveling agents, and polymerization inhibitors as needed.

[0183] As a method for manufacturing the sealant for the liquid crystal display element of the present invention, examples include: a method of mixing a curable resin, a photopolymerization initiator, and a silane coupling agent added as needed using a mixer such as a homogenizer, a homogenizer, a universal mixer, a planetary mixer, a kneader, or a three-roll mill.

[0184] The sealant for liquid crystal display elements of the present invention preferably has a glass transition temperature of 85°C or higher after curing. By setting the glass transition temperature of the cured material to 85°C or higher, the sealant for liquid crystal display elements of the present invention can produce liquid crystal display elements with superior reliability even when exposed to high temperature and high humidity environments. A more preferred lower limit for the glass transition temperature of the cured material is 100°C.

[0185] Furthermore, from the viewpoint of adhesion to substrates, etc., the preferred upper limit of the glass transition temperature of the cured material is 150°C, and a more preferred upper limit is 130°C.

[0186] It should be noted that the glass transition temperature of the aforementioned cured material can be obtained as the temperature at which the loss tangent (tanδ) reaches its maximum value when dynamic viscoelasticity is measured using a dynamic viscoelasticity measuring device at -80 to 200°C and 10 Hz. Furthermore, the cured material used for measuring the aforementioned glass transition temperature was subjected to irradiation with a sealant at 3000 mJ / cm² on a liquid crystal display element. 2 After being exposed to light, the product is cured by heating at 120°C for 60 minutes.

[0187] By incorporating conductive microparticles into the sealant for liquid crystal display elements of the present invention, it is possible to manufacture a material with both vertical and horizontal conductivity.

[0188] As the aforementioned conductive particles, metal spheres or conductive particles with a conductive metal layer formed on the surface of resin particles can be used. Among these, conductive particles with a conductive metal layer formed on the surface of resin particles are suitable because they can achieve conductive connections without damaging the transparent substrate, thanks to the excellent elasticity of the resin particles.

[0189] A liquid crystal display element containing a cured sealant for liquid crystal display elements according to the present invention is also one of the present inventions.

[0190] Furthermore, as the liquid crystal display element of the present invention, a liquid crystal display element with a narrow bezel design is preferred. Specifically, the width of the frame portion surrounding the liquid crystal display unit is preferably 2 mm or less.

[0191] Furthermore, the coating width of the sealant for the liquid crystal display element of the present invention is preferably 1 mm or less when manufacturing the liquid crystal display element of the present invention.

[0192] The sealant for liquid crystal display elements of the present invention is suitable for use in the manufacture of liquid crystal display elements based on liquid crystal droplet technology. Examples of methods for manufacturing the liquid crystal display elements of the present invention using the liquid crystal droplet technology include the following.

[0193] First, a step is performed in which the sealant for liquid crystal display elements of the present invention is applied to one of two transparent substrates having electrodes such as ITO thin films and alignment films to form a frame-shaped sealing pattern by screen printing, dispensing, or other methods. Next, a step is performed in which, while the sealant for liquid crystal display elements of the present invention is not cured, tiny droplets of liquid crystal are applied to the frame of the sealing pattern on the substrate, and another transparent substrate is superimposed under vacuum. Then, a liquid crystal display element can be obtained by performing a step in which the sealant for liquid crystal display elements of the present invention is photocured by irradiating the sealing pattern portion of the sealant for liquid crystal display elements of the present invention with long-wavelength light through a cutoff filter or the like. In addition to the above-mentioned photocuring step, a step of heating the sealant to thermally cure it can also be performed.

[0194] Invention Effects

[0195] According to the present invention, a sealant for liquid crystal display elements is provided that exhibits excellent visible light curability and adhesion to alignment films, and enables the production of liquid crystal display elements with excellent reliability. Furthermore, according to the present invention, a liquid crystal display element manufactured using this sealant is also provided. Detailed Implementation

[0196] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0197] (Preparation of the compound shown in formula (2-1))

[0198] Prepare a 200 mL three-necked round-bottom flask equipped with a thermometer, condenser, Dean-Stark separator, dropping funnel, and stirrer. Add 38 g of 2,2-bis(2-hydroxy-5-biphenyl)propane (Tokyo Chemical Industries, Ltd.), 174 g of epichlorohydrin (Tokyo Chemical Industries, Ltd.), and 3.8 g of benzyltrimethylammonium chloride (Tokyo Chemical Industries, Ltd.) to the flask. Next, heat the resulting mixture to approximately 50 °C under reduced pressure (50 torr) with stirring, and add 28.2 g of 48% sodium hydroxide aqueous solution (Kanto Chemical Co., Ltd.) dropwise over 3 hours. Stirring continues while returning epichlorohydrin to the reaction system in the water / epichlorohydrin mixture distilled via azeotropic extraction. After the addition is complete, continue stirring for 3 hours. Next, cool the reaction mixture to room temperature, add 90 g of toluene and 30 g of methyl isobutyl ketone, and wash four times with 150 mL of water. The solvent in the obtained organic phase was removed by vacuum distillation, yielding 38 g of the compound represented by formula (2-1) above, which was a yellow, transparent, viscous substance. The structure of the compound represented by formula (2-1) obtained was determined by... 1 H-NMR, 13 Confirmed by C-NMR and FT-IR.

[0199] (Preparation of the compound shown in formula (2-2))

[0200] Using 26g of 4,4'-dihydroxy-p-terphenyl instead of 38g of 2,2-bis(2-hydroxy-5-biphenyl)propane, the same procedure as described above (Preparation of the compound shown in formula (2-1)) was followed to obtain 26g of the compound shown in formula (2-2). The structure of the obtained compound shown in formula (2-2) was determined by... 1 H-NMR, 13 Confirmed by C-NMR and FT-IR.

[0201] (Preparation of the compound shown in formula (2-3))

[0202] Using 44g of 5,5'-(1-phenylethylene)bis[(1,1'-biphenyl)-2-ol] instead of 38g of 2,2-bis(2-hydroxy-5-biphenyl)propane, the same procedure as described above for the preparation of the compound shown in formula (2-1) was followed to obtain 44g of the compound shown in formula (2-3).

[0203] The structure of the compound shown in formula (2-3) is obtained by... 1 H-NMR, 13 Confirmed by C-NMR and FT-IR.

[0204] (Preparation of the compound shown in formula (2-4))

[0205] Using 35g of 4,4'-dihydroxytetraphenylmethane instead of 38g of 2,2-bis(2-hydroxy-5-biphenyl)propane, the same procedure as described above (Preparation of the compound shown in formula (2-1)) was followed to obtain 35g of the compound shown in formula (2-4).

[0206] The structure of the compound shown in formula (2-4) is obtained by... 1 H-NMR, 13 Confirmed by C-NMR and FT-IR.

[0207] (Synthesis of the compound shown in formula (5-1))

[0208] Five parts by weight of N-ethylcarbazole, 2.81 parts by weight of 2,5-thiophene dicarboxylate chloride, and 3.76 parts by weight of aluminum chloride were added to 40 mL of dichloromethane and stirred overnight at room temperature. Two parts by weight of acetyl chloride and 3.76 parts by weight of aluminum chloride were added to the resulting reaction solution, and the mixture was stirred further at room temperature for 4 hours. The resulting reaction solution was then injected into ice water, and the organic layer was extracted with ethyl acetate. The extracted solution was washed with saturated sodium bicarbonate aqueous solution and brine, dried over anhydrous magnesium sulfate, and concentrated to give product (A1).

[0209] Three parts by weight of the obtained product (A1), 0.76 parts by weight of ammonium hydroxychloride, and 0.86 parts by weight of pyridine were added to 30 mL of ethanol, and the mixture was refluxed and stirred for 10 hours. The resulting reaction solution was then poured into ice water and filtered. The filtrate was washed with water, dissolved in ethyl acetate, dried over anhydrous magnesium sulfate, and concentrated to obtain product (B1).

[0210] 1.5 parts by weight of the obtained product (B1) were dissolved in 25 parts by weight of N,N-dimethylformamide, and then 0.59 parts by weight of acetyl chloride were added. While cooling the resulting solution to below 10°C, 0.78 parts by weight of triethylamine were added dropwise, and the mixture was stirred at room temperature for 4 hours. The resulting reaction solution was injected into water and filtered. The filtrate was purified by silica gel column chromatography using a mixed solvent of dichloromethane and hexane (dichloromethane:hexane = 2:1) to obtain the compound shown in formula (5-1) above.

[0211] It should be noted that the structure of the compound shown in formula (5-1) above is obtained through... 1 H-NMR, 13 Confirmed by C-NMR and FT-IR.

[0212] (Synthesis of the compound shown in formula (5-2))

[0213] Five parts by weight of N-(2-ethylhexyl)carbazole, 2.81 parts by weight of 2,5-thiophene dicarboxylate chloride, and 3.76 parts by weight of aluminum chloride were added to 40 mL of dichloromethane and stirred overnight at room temperature. Two parts by weight of acetyl chloride and 3.76 parts by weight of aluminum chloride were added to the resulting reaction solution, and the mixture was stirred further at room temperature for 4 hours. The resulting reaction solution was then injected into ice water, and the organic layer was extracted with ethyl acetate. The extracted solution was washed with saturated sodium bicarbonate aqueous solution and brine, dried over anhydrous magnesium sulfate, and concentrated to give product (A2).

[0214] Three parts by weight of the obtained product (A2), 0.76 parts by weight of ammonium hydroxychloride, and 0.86 parts by weight of pyridine were added to 30 mL of ethanol, and the mixture was stirred under reflux for 10 hours. The resulting reaction solution was then poured into ice water and filtered. The filtrate was washed with water, dissolved in ethyl acetate, dried over anhydrous magnesium sulfate, and concentrated to obtain product (B2).

[0215] 1.5 parts by weight of the obtained product (B2) were dissolved in 25 parts by weight of N,N-dimethylformamide, and then 0.59 parts by weight of acetyl chloride were added. While cooling the resulting solution to below 10°C, 0.78 parts by weight of triethylamine were added dropwise, and the mixture was stirred at room temperature for 4 hours. The resulting reaction solution was injected into water and filtered. The filtrate was purified by silica gel column chromatography using a mixed solvent of dichloromethane and hexane (dichloromethane:hexane = 2:1) to obtain the compound shown in formula (5-2) above.

[0216] It should be noted that the structure of the compound shown in formula (5-2) above is obtained through... 1 H-NMR, 13 Confirmed by C-NMR and FT-IR.

[0217] (Synthesis of the compound shown in formula (5-3))

[0218] Five parts by weight of ethyl 3-(9H-carbazole-9-yl)propionate, 2.64 parts by weight of hexanoyl chloride, and 2.62 parts by weight of aluminum chloride were added to 80 mL of dichloromethane and stirred overnight at room temperature. 1.84 parts by weight of 2,5-thiophenecarboxylic acid chloride and 5.24 parts by weight of aluminum chloride were added to the resulting reaction solution, and the mixture was stirred further at room temperature for 4 hours. The resulting reaction solution was then injected into ice water, and the organic layer was extracted with ethyl acetate. The extracted solution was washed with saturated aqueous sodium bicarbonate solution and brine, dried over anhydrous sodium sulfate, and concentrated to give product (A3).

[0219] To 4.0 parts by weight of product (A3) in 20 mL of ethanol, 2.77 parts by weight of 20% sodium hydroxide aqueous solution were added, and the mixture was refluxed for 3 hours. After the reaction was complete, 50 mL of water was added, and the solution was adjusted to acidity with concentrated hydrochloric acid. The mixture was then extracted with ethyl acetate. The ethyl acetate layer was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated to obtain product (B3).

[0220] Three parts by weight of the obtained product (B3), 0.58 parts by weight of ammonium hydroxychloride, and 0.65 parts by weight of pyridine were added to 30 mL of ethanol, and the mixture was stirred under reflux for 10 hours. The resulting reaction solution was then poured into ice water and filtered. The filtrate was washed with water, dissolved in ethyl acetate, dried over anhydrous sodium sulfate, and concentrated to obtain product (C3).

[0221] 1.5 parts by weight of the obtained product (C3) were dissolved in 20 parts by weight of N,N-dimethylformamide, and then 0.45 parts by weight of acetyl chloride were added. While cooling the resulting solution to below 10°C, 0.59 parts by weight of triethylamine were added dropwise, and the mixture was stirred at room temperature for 4 hours. The resulting reaction solution was injected into water and filtered. The compound was separated by silica gel column chromatography, thus yielding the compound represented by formula (5-3) above.

[0222] It should be noted that the structure of the compound shown in formula (5-3) above is obtained through... 1 H-NMR, 13 Confirmed by C-NMR and FT-IR.

[0223] (Examples 1-11, Comparative Examples 1-4)

[0224] According to the mixing ratios recorded in Tables 1 and 2, each material was stirred using a planetary mixer (THINKY Corporation, "Defoaming Rentarō") and then uniformly mixed using a ceramic three-roll mill to obtain the sealants for liquid crystal display elements of Examples 1 to 11 and Comparative Examples 1 to 4.

[0225] <Evaluation>

[0226] The sealants used to obtain the liquid crystal display elements in the examples and comparative examples were evaluated as follows. The results are shown in Tables 1 and 2.

[0227] (Visible light curing property)

[0228] One part by weight of spacer particles was dispersed in 100 parts by weight of sealant for each liquid crystal display element obtained in the Examples and Comparative Examples. Micropearl SI-H050 (manufactured by Sekisui Chemicals Co., Ltd.) was used as the spacer particles. Next, the sealant was filled into a dispensing syringe, degassed, and then applied to a glass substrate using a dispenser. A PSY-10E (manufactured by Musashi Engineering Co., Ltd.) was used as the dispensing syringe, and a SHOTMASTER300 (manufactured by Musashi Engineering Co., Ltd.) was used as the dispenser. Glass substrates of the same size were bonded to the sealant-coated substrate using a vacuum bonding device under reduced pressure of 5 Pa. The sealant portion of the bonded glass substrate was irradiated with a metal halide lamp at 100 mW / cm². 2 The light was applied for 10 seconds. The light was then passed through a cutoff filter (420nm cutoff filter) that blocks light with wavelengths below 420nm.

[0229] The sealant was subjected to FT-IR spectroscopy using an infrared spectrometer to measure the change in the peak originating from the (meth)acryloyl group before and after light irradiation. An FTS3000 (manufactured by BIORAD) infrared spectrometer was used. A reduction of more than 80% in the peak originating from the (meth)acryloyl group after light irradiation was marked as "ο", a reduction of more than 50% but less than 80% was marked as "△", and a reduction of less than 50% was marked as "×". Visible light curability was evaluated in this way.

[0230] (Adhesion to the alignment film)

[0231] One part by weight of spacer particles was dispersed in 100 parts by weight of the sealant for liquid crystal display elements obtained in the Examples and Comparative Examples. A very small amount of the sealant for liquid crystal display elements containing the spacer particles was taken to the center of a glass substrate having a TN polyimide alignment film (manufactured by Nissan Chemical Co., Ltd., "SE6414"), and a glass substrate having a TN polyimide alignment film of the same type was superimposed on it. The sealant for liquid crystal display elements was spread out and irradiated with a metal halide lamp at 100 mW / cm². 2 After 30 seconds of exposure to light, the liquid crystal display element was heated at 120°C for 1 hour to cure the sealant, thus obtaining the bonding test piece.

[0232] For each of the obtained bonding test pieces, the bonding strength (adhesive force) was determined using a tension meter.

[0233] With a bonding strength of 12 kg / cm 2 The above situation is marked as "ο", and 7.0 kg / cm 2 Above and below 12 kg / cm 2 The case where the bond strength is less than 7.0 kg / cm² is marked as “△”. 2 The condition is marked as "×", which evaluates the adhesion to the orientation film.

[0234] (Solubility)

[0235] The curable resin and photopolymerization initiator were mixed using the same materials and proportions as in the examples and comparative examples, and heated at 80°C for 20 minutes. The heated mixture was sandwiched between two glass plates while maintaining a 20 μm gap, and the transmitted light intensity was measured using a UV-Vis spectrophotometer (Varian, “Carry-5spctrophotometer”).

[0236] Based on the above measurements, cases where the reduction rate of transmitted light intensity at a wavelength of 500 nm is less than 20% are marked as "ο", cases where it is more than 20% but less than 40% are marked as "△", and cases where it is more than 40% are marked as "×", thus evaluating solubility.

[0237] (Glass transition temperature of the cured product)

[0238] The liquid crystal display elements obtained in the examples and comparative examples were irradiated with a sealant at 100 mW / cm² using a metal halide lamp. 2 After 30 seconds of exposure to light, the sample was heated at 120°C for 1 hour to prepare a 300 μm thick film as a test piece. The dynamic viscoelasticity of the obtained test piece was measured using a dynamic viscoelasticity measuring device (IT Measurement & Control Co., Ltd., "DVA-200") at -50°C to 200°C and 5 Hz. The temperature at which the loss tangent (tanδ) reached its maximum value was determined as the glass transition temperature.

[0239] [Table 1]

[0240]

[0241] [Table 2]

[0242]

[0243] Industrial availability

[0244] According to the present invention, a sealant for liquid crystal display elements is provided that exhibits excellent visible light curability and adhesion to alignment films, and enables the production of liquid crystal display elements with excellent reliability. Furthermore, according to the present invention, a liquid crystal display element manufactured using this sealant is also provided.

Claims

1. A sealant for liquid crystal display elements, characterized in that, a curable resin and a photopolymerization initiator, the curable resin contains a compound having an aromatic ring and a polymerizable functional group, and the content ratio of the aromatic ring is 50% or more, the photopolymerization initiator contains a compound having one or more photopolymerization initiation groups and three or more heterocyclic rings in one molecule, of the heterocyclic rings possessed by the compound having one or more photopolymerization initiation groups and three or more heterocyclic rings in one molecule, at least one is a thiophene ring, the difference between the solubility parameter of the entire curable resin and that of the compound having one or more photopolymerization initiation groups and three or more heterocyclic rings in one molecule is 2.0 or less.

2. The sealant for liquid crystal display elements according to claim 1, wherein the content of the compound having an aromatic ring and a polymerizable functional group, and the content ratio of the aromatic ring being 50% or more, in 100 parts by weight of the entire curable resin is 15 parts by weight or more.

3. The sealant for liquid crystal display elements according to claim 1 or 2, wherein, the glass transition temperature of the cured product is 85°C or more.

4. The sealant for liquid crystal display elements according to claim 1 or 2, wherein the aromatic ring in the compound having an aromatic ring and a polymerizable functional group, and the content ratio of the aromatic ring being 50% or more, is a benzene ring.

5. A liquid crystal display element comprising a cured product of the sealing agent for a liquid crystal display element according to claim 1, 2, 3 or 4.

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