Sealant for liquid crystal display element and liquid crystal display element

Abstract

To provide a sealant for a liquid crystal display element that excels in adhesiveness to an alignment film, moisture permeability prevention, and low liquid crystal contamination, and a liquid crystal display element formed by using the sealant for the liquid crystal display element.SOLUTION: Provided is a sealant for a liquid crystal display element that contains a curable resin, a photoradical polymerization initiator, and a thermosetting agent. The curable resin contains a (meth)acrylic compound not having an epoxy group, and an epoxy compound. The (meth)acrylic compound contains a compound having one (meth)acryloyloxy group in one molecule, and a compound having three or more (meth)acryloyloxy groups in one molecule. The compound having one (meth)acryloyloxy group in the one molecule has a carbon ring and does not have a hetero ring.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a sealing agent for liquid crystal display elements. The present invention also relates to a liquid crystal display element using the sealing agent for liquid crystal display elements.

Background Art

[0002] In recent years, as a method for manufacturing liquid crystal elements, from the viewpoints of shortening the tact time and optimizing the amount of liquid crystal used, a liquid crystal dropping method called a dropping method using a photothermal dual-curing type sealing agent containing a curable resin, a photopolymerization initiator, and a thermosetting agent, as disclosed in Patent Document 1 and Patent Document 2, has been used. In the dropping method, first, a rectangular seal pattern is formed by dispensing on one of two substrates with electrodes. Next, minute droplets of liquid crystal are dropped into the seal frame of the substrate while the sealing agent is in an uncured state, the other substrate is overlapped under vacuum, and the seal portion is irradiated with light such as ultraviolet light for temporary curing. Then, it is heated for final curing to produce a liquid crystal element. Currently, this dropping method has become the mainstream of the method for manufacturing liquid crystal elements.

[0003] By the way, in modern times when various mobile devices with liquid crystal panels such as mobile phones and portable game machines are widespread, miniaturization of the devices is the most demanded issue. As a method for miniaturizing the devices, narrowing the bezel of the liquid crystal display portion is mentioned. For example, the position of the seal portion is arranged under the black matrix (hereinafter, also referred to as narrow bezel design).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] With the narrow border design, in a liquid crystal display element, the distance from the pixel region to the sealant is short, and in addition to the fact that uneven display is likely to occur due to contamination of the liquid crystal by the sealant, since the sealant is often disposed on the alignment film, the sealant is required to have excellent low liquid crystal contamination property and adhesiveness to the alignment film. In addition, with the spread of tablet terminals and mobile terminals, the liquid crystal display element is increasingly required to have moisture resistance reliability in driving under high temperature and high humidity environments, etc., and the sealant is further required to have the performance of preventing intrusion of water from the outside. Therefore, it is necessary to improve the moisture permeability preventing property of the sealant. However, the line width of the sealant applied with the narrow border design has become narrow, and it has been difficult to obtain a sealant having excellent moisture permeability preventing property even in the case of being thinned.

[0006] An object of the present invention is to provide a sealant for a liquid crystal display element having excellent adhesiveness to an alignment film, moisture permeability preventing property, and low liquid crystal contamination property. Another object of the present invention is to provide a liquid crystal display element using the sealant for a liquid crystal display element.

Means for Solving the Problems

[0007] The present disclosure 1 contains a curable resin, a photo radical polymerization initiator, and a thermosetting agent. The curable resin includes a (meth)acrylic compound having no epoxy group and an epoxy compound. The (meth)acrylic compound includes a compound having one (meth)acryloyloxy group in one molecule and a compound having three or more (meth)acryloyloxy groups in one molecule. The compound having one (meth)acryloyloxy group in one molecule has a carbocyclic ring and does not have a heterocyclic ring, and is a sealant for a liquid crystal display element. The present disclosure 2 is the sealant for a liquid crystal display element of the present disclosure 1, wherein the compound having one (meth)acryloyloxy group in one molecule has a structure in which the (meth)acryloyloxy group and the carbocyclic ring are directly bonded. The sealant for liquid crystal display elements of the present disclosure 1 or 2 is such that the content of the compound having one (meth)acryloyloxy group in one molecule in 100 parts by mass of the above curable resin is 5 parts by mass or more and 15 parts by mass or less. The sealant for liquid crystal display elements of the present disclosure 4 is such that the content ratio of the compound having one (meth)acryloyloxy group in one molecule to 100 parts by mass of the compound having three or more (meth)acryloyloxy groups in one molecule is 100 parts by mass or more and 150 parts by mass or less in the sealant for liquid crystal display elements of the present disclosure 1, 2 or 3. The sealant for liquid crystal display elements of the present disclosure 5 further contains a filler in the sealant for liquid crystal display elements of the present disclosure 1, 2, 3 or 4. The sealant for liquid crystal display elements of the present disclosure 6 further contains a silane coupling agent in the sealant for liquid crystal display elements of the present disclosure 1, 2, 3, 4 or 5. The liquid crystal display element of the present disclosure 7 includes a cured product of the sealant for liquid crystal display elements of the present disclosure 1, 2, 3, 4, 5 or 6. The present invention will be described in detail below.

[0008] In order to impart flexibility to the sealant and exhibit excellent adhesiveness by improving the wettability at the interface with the adherend, the inventor blended a monofunctional (meth)acrylic compound with the curable resin, and further, in order to improve the moisture barrier property, considered using a monofunctional (meth)acrylic compound having a bulky carbocyclic ring containing no heteroatom. However, in some cases, the sealant components eluted into the liquid crystal, causing liquid crystal contamination. Therefore, as a result of further intensive studies by the inventor, by using a trifunctional or higher functional (meth)acrylic compound in combination with the monofunctional (meth)acrylic compound as the curable resin, it was found that a sealant for liquid crystal display elements excellent in adhesiveness to the alignment film, moisture barrier property, and low liquid crystal contamination property can be obtained, and the present invention was completed.

[0009] The sealant for liquid crystal display elements of the present invention contains a curable resin. The above curable resin contains a (meth)acrylic compound having no epoxy group and an epoxy compound. In the present specification, the above “(meth)acryl” means acrylic or methacrylic.

[0010] The above (meth)acrylic compound includes a compound having one (meth)acryloyloxy group in one molecule (hereinafter, also referred to as “monofunctional (meth)acrylic compound”). The above monofunctional (meth)acrylic compound has a carbocyclic ring and does not have a heterocyclic ring. By containing a monofunctional (meth)acrylic compound having a carbocyclic ring and not having a heterocyclic ring (hereinafter, also referred to as “the monofunctional (meth)acrylic compound according to the present invention”), the sealant for liquid crystal display elements of the present invention is excellent in adhesiveness to the alignment film and moisture permeation prevention property. In the present specification, the above “(meth)acryloyl” means acryloyl or methacryloyl.

[0011] In the monofunctional (meth)acrylic compound according to the present invention, the above carbocyclic ring may be an aliphatic ring or an aromatic ring. Further, the monofunctional (meth)acrylic compound according to the present invention may have only one of the above carbocyclic rings in one molecule, or may have two or more thereof.

[0012] Examples of the monofunctional (meth)acrylic compound according to the present invention include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, 1-ethylcyclopentyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, phenyl (meth)acrylate, and the like. Among them, the monofunctional (meth)acrylic compound according to the present invention preferably has a structure in which the above (meth)acryloyloxy group and the above carbocyclic ring are directly bonded from the viewpoint of making the obtained sealant for liquid crystal display elements more excellent in moisture permeation prevention property. In the present specification, the above-mentioned "(meth)acrylate" means acrylate or methacrylate.

[0013] The preferable lower limit of the content of the monofunctional (meth)acrylic compound according to the present invention in 100 parts by mass of the curable resin is 5 parts by mass, and the preferable upper limit is 15 parts by mass. When the content of the monofunctional (meth)acrylic compound according to the present invention is 5 parts by mass or more, the obtained sealant for liquid crystal display elements becomes excellent in adhesion to the alignment film and moisture permeation prevention properties. When the content of the monofunctional (meth)acrylic compound according to the present invention is 15 parts by mass or less, the obtained sealant for liquid crystal display elements becomes excellent in low liquid crystal contamination properties. The more preferable lower limit of the content of the monofunctional (meth)acrylic compound according to the present invention is 6 parts by mass, and the more preferable upper limit is 14 parts by mass.

[0014] The preferable lower limit of the content ratio of the monofunctional (meth)acrylic compound according to the present invention to 100 parts by mass of the compound having three or more (meth)acryloyloxy groups in one molecule described later is 100 parts by mass, and the preferable upper limit is 150 parts by mass. When the content ratio of the monofunctional (meth)acrylic compound according to the present invention to 100 parts by mass of the compound having three or more (meth)acryloyloxy groups in one molecule is 100 parts by mass or more, the obtained sealant for liquid crystal display elements becomes excellent in adhesion to the alignment film and moisture permeation prevention properties. When the content ratio of the monofunctional (meth)acrylic compound according to the present invention to 100 parts by mass of the compound having three or more (meth)acryloyloxy groups in one molecule is 150 parts by mass or less, the obtained sealant for liquid crystal display elements becomes excellent in low liquid crystal contamination properties. The more preferable lower limit of the content ratio of the monofunctional (meth)acrylic compound according to the present invention to 100 parts by mass of the compound having three or more (meth)acryloyloxy groups in one molecule is 105 parts by mass, and the more preferable upper limit is 145 parts by mass.

[0015] The above (meth)acrylic compound includes a compound having three or more (meth)acryloyloxy groups in one molecule (hereinafter, also referred to as "a trifunctional or higher (meth)acrylic compound"). By containing the trifunctional or higher (meth)acrylic compound, the sealant for liquid crystal display elements of the present invention is excellent in low liquid crystal contamination property.

[0016] Examples of the trifunctional or higher (meth)acrylic compound include ethylene oxide-added isocyanuric acid tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane 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, dipentaerythritol hexa(meth)acrylate, and the like. Among them, from the viewpoint of making the obtained sealant for liquid crystal display elements more excellent in low liquid crystal contamination property, the (meth)acrylic compound preferably includes, as the trifunctional or higher (meth)acrylic compound, a compound having four or more (meth)acryloyloxy groups in one molecule.

[0017] Examples of commercially available trifunctional or higher (meth)acrylic compounds include Aronix M-315 (manufactured by Toagosei Co., Ltd.), A-DPH (manufactured by Shin-Nakamura Chemical Co., Ltd.), and the like.

[0018] In 100 parts by mass of the above curable resin, the preferable lower limit of the content of the above trifunctional or higher (meth)acrylic compound is 5 parts by mass, and the preferable upper limit is 15 parts by mass. When the content of the above trifunctional or higher (meth)acrylic compound is 5 parts by mass or more, the sealant for liquid crystal display elements obtained will be excellent in low liquid crystal contamination. When the content of the above trifunctional or higher (meth)acrylic compound is 15 parts by mass or less, the cured product of the sealant for liquid crystal display elements obtained will be excellent in adhesion to the alignment film and moisture permeability prevention. The more preferable lower limit of the content of the above trifunctional or higher (meth)acrylic compound is 6 parts by mass, and the more preferable upper limit is 14 parts by mass.

[0019] The above (meth)acrylic compound may contain other (meth)acrylic compounds in addition to the monofunctional (meth)acrylic compound according to the present invention and the above trifunctional or higher (meth)acrylic compound. The above other (meth)acrylic compounds are other monofunctional (meth)acrylic compounds other than the monofunctional (meth)acrylic compound according to the present invention, or compounds having two (meth)acryloyl groups in one molecule (hereinafter, also referred to as "bifunctional (meth)acrylic compounds"). Among them, from the viewpoint of making the sealant for liquid crystal display elements obtained excellent in curability, adhesiveness, and low liquid crystal contamination, it is preferable to contain a bifunctional (meth)acrylic compound.

[0020] Examples of the above bifunctional (meth)acrylic compound include bifunctional epoxy (meth)acrylate, bifunctional (meth)acrylate compound, bifunctional urethane (meth)acrylate, etc. Among them, bifunctional epoxy (meth)acrylate is preferable. In addition, in this specification, the above epoxy (meth)acrylate means a compound obtained by reacting all epoxy groups in an epoxy compound with (meth)acrylic acid.

[0021] Examples of the bifunctional epoxy (meth)acrylate include those obtained by reacting a bifunctional epoxy compound with (meth)acrylic acid in the presence of a basic catalyst according to a conventional method.

[0022] Examples of the bifunctional epoxy compound serving as a raw material for the bifunctional epoxy (meth)acrylate 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-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, glycidylamine type epoxy compounds, alkyl polyol type epoxy compounds, rubber-modified epoxy compounds, glycidyl ester compounds, and the like.

[0023] Examples of the bifunctional (meth)acrylic acid ester compound 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, neopentyl glycol di(meth)acrylate, ethylene oxide adduct bisphenol A di(meth)acrylate, propylene oxide adduct bisphenol A di(meth)acrylate, ethylene oxide adduct bisphenol F di(meth)acrylate, dimethylol dicyclopentenyl 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, polybutadiene diol di(meth)acrylate, and the like.

[0024] The urethane (meth)acrylate can be obtained, for example, by reacting a (meth)acrylic acid derivative having a hydroxyl group with a bifunctional isocyanate compound in the presence of a catalytic amount of a tin-based compound.

[0025] Examples of the bifunctional isocyanate compound include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, tetramethylxylylene diisocyanate, and the like.

[0026] In addition, as the bifunctional isocyanate compound, a chain-extended bifunctional isocyanate compound obtained by reacting a polyol with an excessive bifunctional isocyanate compound can also be used. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, polycaprolactone diol, and the like.

[0027] Examples of the (meth)acrylic acid derivative having a hydroxyl group include hydroxyalkyl mono(meth)acrylate, mono(meth)acrylate of a divalent alcohol, mono(meth)acrylate of a trivalent alcohol, and the like. Examples of the hydroxyalkyl mono(meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like. Examples of the divalent alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, polyethylene glycol, and the like. Examples of the trivalent alcohol include trimethylolethane, trimethylolpropane, glycerin, and the like.

[0028] When the curable resin contains the other (meth)acrylic compound, the preferable lower limit of the content of the other (meth)acrylic compound in 100 parts by mass of the curable resin is 50 parts by mass, and the preferable upper limit is 80 parts by mass. When the content of the other (meth)acrylic compound is within this range, the sealant for liquid crystal display elements obtained becomes excellent in curability, adhesiveness, and low liquid crystal contamination property. The more preferable lower limit of the content of the other (meth)acrylic compound is 45 parts by mass, and the more preferable upper limit is 75 parts by mass.

[0029] Examples of the epoxy compound contained in the curable resin include bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, 2,2'-diallylbisphenol A type epoxy compound, hydrogenated bisphenol type epoxy compound, propylene oxide-added bisphenol A type epoxy compound, resorcinol type epoxy compound, biphenyl type epoxy compound, sulfide type epoxy compound, diphenyl ether type epoxy compound, dicyclopentadiene type epoxy compound, naphthalene type epoxy compound, phenol novolak type epoxy compound, orthocresol novolak type epoxy compound, dicyclopentadiene novolak type epoxy compound, biphenyl novolak type epoxy compound, naphthalene phenol novolak type epoxy compound, glycidylamine type epoxy compound, alkyl polyol type epoxy compound, rubber-modified type epoxy compound, glycidyl ester compound, and the like.

[0030] As the epoxy compound, a partially (meth)acrylic-modified epoxy compound is also preferably used. In the present specification, the above-mentioned partial (meth)acryl-modified epoxy compound means a compound having one or more epoxy groups and one or more (meth)acryloyl groups in one molecule, which is obtained by reacting an epoxy group of a part of an epoxy compound having two or more epoxy groups with (meth)acrylic acid. Although the above-mentioned partial (meth)acryl-modified epoxy compound has a (meth)acryloyl group, it is treated as the above-mentioned epoxy compound rather than the above-mentioned (meth)acrylic compound.

[0031] Examples of commercially available products among the above-mentioned partial (meth)acryl-modified epoxy compounds include UVACURE1561, KRM8287 (both manufactured by Daicel Ornex Co., Ltd.), and the like.

[0032] The preferable lower limit of the content of the above-mentioned epoxy compound in 100 parts by mass of the above-mentioned curable resin is 10 parts by mass, and the preferable upper limit is 40 parts by mass. When the content of the above-mentioned epoxy compound is within this range, the sealant for liquid crystal display elements obtained is excellent in curability, adhesiveness, and low liquid crystal contamination. The more preferable lower limit of the content of the above-mentioned epoxy compound is 15 parts by mass, and the more preferable upper limit is 35 parts by mass.

[0033] The preferable lower limit of the content of the entire above-mentioned curable resin in 100 parts by mass of the sealant for liquid crystal display elements of the present invention is 40 parts by mass, and the preferable upper limit is 70 parts by mass. When the content of the entire above-mentioned curable resin is within this range, the sealant for liquid crystal display elements obtained is excellent in curability and adhesiveness. The more preferable lower limit of the content of the entire above-mentioned curable resin is 45 parts by mass, and the more preferable upper limit is 65 parts by mass.

[0034] The sealant for liquid crystal display elements of the present invention contains a photo radical polymerization initiator. Examples of the above-mentioned photo radical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, thioxanthone compounds, and the like. Specific examples of the above-mentioned photo radical polymerization initiator include, for example, 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-diphenylethane-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 1-(4-(2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-(phenylthio)phenyl)-1,2-octanedione 2-(O-benzoyloxime), 2-(acetoxyimino)-1-(4-(4-(2-hydroxyethoxy)phenylthio)phenyl)propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4-dimethylthioxanthen-9-one, and the like.

[0035] The content of the above-mentioned photo radical polymerization initiator preferably has a lower limit of 0.01 part by mass and an upper limit of 10 parts by mass with respect to 100 parts by mass of the above-mentioned curable resin. When the content of the above-mentioned photo radical polymerization initiator is within this range, the sealant for liquid crystal display elements obtained will be excellent in storage stability and photocurability. A more preferable lower limit of the content of the above-mentioned photo radical polymerization initiator is 0.1 part by mass, and a more preferable upper limit is 5 parts by mass.

[0036] The sealant for liquid crystal display elements of the present invention may contain a thermal radical polymerization initiator. Examples of the above-mentioned thermal radical polymerization initiator include those composed of azo compounds, organic peroxides, and the like. Among them, from the viewpoint of suppressing liquid crystal contamination, an initiator composed of an azo compound (hereinafter also referred to as an "azo initiator") is preferable. The above-mentioned thermal radical polymerization initiator may be used alone or in combination of two or more.

[0037] Examples of the azo compound include those having a structure in which a plurality of units such as polyalkylene oxide and polydimethylsiloxane are bonded via an azo group. As the polymer azo compound having a structure in which a plurality of units such as polyalkylene oxide are bonded via the azo group, those having a polyethylene oxide structure are preferable. Specific examples of the azo compound include polycondensates of 4,4'-azobis(4-cyanopentanoic acid) and polyalkylene glycol, and polycondensates of 4,4'-azobis(4-cyanopentanoic acid) and polydimethylsiloxane having a terminal amino group. Examples of the azo initiator include VPE-0201, VPE-0401, VPE-0601, VPS-0501, VPS-1001, V-65, V-501 (all manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.).

[0038] Examples of the organic peroxide include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, peroxydicarbonate, and the like.

[0039] The content of the thermal radical polymerization initiator preferably has a lower limit of 0.01 part by mass and an upper limit of 10 parts by mass with respect to 100 parts by mass of the curable resin. When the content of the thermal radical polymerization initiator is within this range, the sealant for liquid crystal display elements obtained is excellent in storage stability and thermosetting properties. A more preferable lower limit of the content of the thermal radical polymerization initiator is 0.1 part by mass, and a more preferable upper limit is 5 parts by mass.

[0040] The sealant for liquid crystal display elements of the present invention contains a thermosetting agent. Examples of the thermosetting agent include organic acid hydrazide, imidazole derivatives, amine compounds, polyhydric phenol compounds, acid anhydrides, and the like. Among them, organic acid hydrazide is preferably used.

[0041] Examples of the organic acid hydrazide include sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, malonic acid dihydrazide, and the like. Examples of the commercially available organic acid hydrazides include those manufactured by Otsuka Chemical Co., Ltd., Ajinomoto Fine-Techno Co., Inc., and Nippon Fine Chemical Co., Ltd. Examples of the organic acid hydrazide manufactured by Otsuka Chemical Co., Ltd. include SDH, ADH, and the like. Examples of the organic acid hydrazide manufactured by Ajinomoto Fine-Techno Co., Inc. include Amicure VDH, Amicure VDH-J, Amicure UDH, Amicure UDH-J, and the like. Examples of the organic acid hydrazide manufactured by Nippon Fine Chemical Co., Ltd. include MDH, and the like.

[0042] The content of the above heat curing agent is preferably 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the above curable resin. When the content of the heat curing agent is within this range, the sealant for liquid crystal display elements obtained is excellent in thermosetting properties while maintaining storage stability and coatability. A more preferable upper limit of the content of the heat curing agent is 30 parts by mass.

[0043] The sealant for liquid crystal display elements of the present invention preferably further contains a filler for the purpose of improving viscosity, further improving adhesiveness by a stress dispersion effect, improving the linear expansion coefficient, further improving moisture barrier properties, and the like.

[0044] As the above 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, calcium silicate, and the like. Examples of the organic filler include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, (meth)acrylic polymer fine particles, and the like. Further, the organic filler may have a core-shell structure. The filler may be used alone or in combination of two or more.

[0045] The preferable lower limit of the content of the filler with respect to 100 parts by mass of the curable resin is 10 parts by mass, and the preferable upper limit is 50 parts by mass. When the content of the filler is within this range, the effect such as improvement of adhesiveness is excellent without deteriorating coatability and the like. The more preferable lower limit of the content of the filler is 15 parts by mass, and the more preferable upper limit is 45 parts by mass.

[0046] The sealant for liquid crystal display elements of the present invention preferably further contains a silane coupling agent. The silane coupling agent mainly serves as an adhesion aid for favorably adhering the sealant for liquid crystal display elements to a substrate or the like. Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and the like, which are preferably used.

[0047] The preferable lower limit of the content of the silane coupling agent with respect to 100 parts by mass of the curable resin is 1.0 part by mass, and the preferable upper limit is 3.0 parts by mass. When the content of the silane coupling agent is within this range, the effect of improving adhesiveness is excellent while suppressing the occurrence of liquid crystal contamination. The more preferable lower limit of the content of the silane coupling agent is 1.1 parts by mass, and the more preferable upper limit is 2.9 parts by mass.

[0048] The sealant for liquid crystal display elements of the present invention may further contain additives such as a light-shielding agent, a stress reliever, a reactive diluent, a thixotropic agent, a spacer, a curing accelerator, an antifoaming agent, a leveling agent, and a polymerization inhibitor, if necessary.

[0049] As a method for manufacturing the sealant for liquid crystal display elements of the present invention, for example, a method of mixing a curable resin, a photo radical polymerization initiator, a thermosetting agent, and other components such as an inorganic filler or a silane coupling agent using a mixer can be mentioned. Examples of the above mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mill.

[0050] Moreover, by blending conductive fine particles into the sealant for liquid crystal display elements of the present invention, an upper and lower conduction material can be manufactured. As the above conductive fine particles, metal balls, those in which a conductive metal layer is formed on the surface of resin fine particles, etc. can be used. Among them, those in which a conductive metal layer is formed on the surface of resin fine particles are suitable because conductive connection can be achieved without damaging a transparent substrate or the like due to the excellent elasticity of the resin fine particles.

[0051] A liquid crystal display element including a cured product of the sealant for liquid crystal display elements of the present invention is also one of the present inventions. As the liquid crystal display element of the present invention, a liquid crystal display element with a narrow bezel design is preferable. Specifically, it is preferable that the width of the frame portion around the liquid crystal display portion is 2 mm or less.

[0052] As a method for manufacturing the liquid crystal display element of the present invention, the liquid crystal droplet method is preferably used. Specifically, for example, a method having the following respective steps can be mentioned. First, a step of forming a frame-shaped seal pattern by applying the sealant for liquid crystal display elements of the present invention by screen printing, dispenser coating, etc. on one of two transparent substrates having electrodes such as ITO thin films and alignment films is performed. Next, a step of dropwise applying minute droplets of liquid crystal over the entire surface within the frame of the seal pattern and overlapping the other transparent substrate under vacuum is performed. Then, a liquid crystal display element can be obtained by a method of performing a step of irradiating light such as ultraviolet rays on the seal pattern portion to temporarily cure the sealant (photo-curing step), and a step of heating the temporarily cured sealant to fully cure it (thermo-curing step). When manufacturing the liquid crystal display element of the present invention, the coating width of the sealant for the liquid crystal display element of the present invention is preferably 1 mm or less.

Effects of the Invention

[0053] According to the present invention, it is possible to provide a sealant for a liquid crystal display element that is excellent in adhesiveness to an alignment film, moisture permeation prevention property, and low liquid crystal contamination property. Further, according to the present invention, it is possible to provide a liquid crystal display element using the sealant for the liquid crystal display element.

Embodiments for Carrying Out the Invention

[0054] Examples are shown below to explain the present invention in more detail, but the present invention is not limited to only these examples.

[0055] (Examples 1 to 13, Comparative Examples 1 to 5) According to the blending ratios described in Tables 1 and 2, after stirring each material with a planetary stirrer, it was uniformly mixed with a three-roll ceramic mill to obtain sealants for liquid crystal display elements of Examples 1 to 13 and Comparative Examples 1 to 5. As the planetary stirrer, Awatori Rentaro (manufactured by Shinki Co., Ltd.) was used. Note that the content ratio of ethylene oxide-added triacrylate in Aronix M-315 in Tables 1 and 2 is 87 to 97% by mass.

[0056] The structures of the respective monofunctional (meth)acrylic compounds in Tables 1 and 2 are as follows. Cyclohexyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., "CHA") is a compound represented by the following formula (1-1). Isobornyl acrylate (manufactured by Nippon Shokubai Co., Ltd., "IBOA") is a compound represented by the following formula (1-2). 3-Phenoxybenzyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., "Light Acrylate POB-A") is a compound represented by the following formula (1-3). Cyclic trimethylolpropane formal acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., "Biscoat #200") is a compound represented by the following formula (1-4). Butyl acrylate (manufactured by Mitsubishi Chemical Corporation, "BA") is a compound represented by the following formula (1-5).

[0057] [Chemical formula]

[0058] [Evaluation] The following evaluations were performed on the sealants for each liquid crystal display element obtained in the examples and comparative examples. The results are shown in Tables 1 and 2.

[0059] (Adhesion to the alignment film) To 100 parts by mass of each of the obtained sealants for liquid crystal display elements, 1 part by mass of silica spacer was added and uniformly dispersed using a planetary stirrer. As the silica spacer, SI-H055 (manufactured by Sekisui Chemical Co., Ltd.) was used. A very small amount of the sealant for liquid crystal display elements in which the silica spacer was dispersed was taken at the center of the substrate with an alignment film, and a substrate with the same type of alignment film was overlaid thereon. The substrate with the alignment film was prepared by spin-coating an imide resin (manufactured by Nissan Chemical Industries, Ltd., "SE7492") on a glass substrate with an ITO thin film, pre-baking at 80°C, and then baking at 230°C. The sealant for liquid crystal display elements was spread, and ultraviolet rays of 100 mW / cm 2 were irradiated for 30 seconds using a metal halide lamp, and then heated at 120°C for 1 hour to cure the sealant for liquid crystal display elements, obtaining an adhesion test piece. Regarding the obtained adhesion test piece, the adhesive force was measured using a tension gauge, and the adhesion to the alignment film was evaluated according to the following criteria. ○: When the adhesive force was 2.5 kgf / cm or more △: When the adhesive force was 2.0 kgf / cm or more and less than 2.5 kgf / cm ×: When the adhesive force was less than 2.0 kgf / cm

[0060] (Moisture barrier property) Each sealant for liquid crystal display elements obtained was applied onto a smooth release film using a coater so as to have a thickness of 200 to 300 μm. Next, after irradiating with ultraviolet rays of 100 mW / cm 2 for 30 seconds using a metal halide lamp, it was heated at 120 °C for 1 hour to cure the sealant for liquid crystal display elements, and a film for measuring water vapor transmission rate was obtained. A cup for water vapor transmission rate test was fabricated by a method in accordance with the water vapor transmission rate test method (cup method) of moisture-proof packaging materials of JIS Z 0208. The obtained film for measuring water vapor transmission rate was attached, and it was put into a thermo-hygrostat oven at 80 °C and 90% RH to measure the water vapor transmission rate, and the water vapor barrier property was evaluated according to the following criteria. ◎: When the water vapor transmission rate is less than 70 g / m 2 ·24 hr ○: When the water vapor transmission rate is 70 g / m 2 ·24 hr or more and less than 80 g / m 2 ·24 hr △: When the water vapor transmission rate is 80 g / m 2 ·24 hr or more and less than 90 g / m 2 ·24 hr ×: When the water vapor transmission rate is 90 g / m 2 ·24 hr or more

[0061] (Low liquid crystal contamination) To 100 parts by mass of each obtained sealant for liquid crystal display elements, 1 part by mass of silica spacers was added, uniformly dispersed by a planetary stirring device, and defoamed to remove the bubbles in the sealant for liquid crystal display elements. After that, it was filled into a dispensing syringe and defoamed again. As the silica spacers, SI-H055 (manufactured by Sekisui Chemical Co., Ltd.) was used, and as the dispensing syringe, PSY-10E (manufactured by Musashi Engineering, Inc.) was used. Next, using a dispenser, the sealant for liquid crystal display elements was applied onto a glass substrate so as to draw a frame-shaped seal pattern. As the dispenser, SHOTMASTER300 (manufactured by Musashi Engineering, Inc.) was used. Subsequently, minute droplets of FFS liquid crystal were drop-coated into the frame of the seal pattern using a liquid crystal droplet discharging device. As the FFS liquid crystal, JC-5223XX (manufactured by Chisso Corporation) was used. Another glass substrate was overlaid on the glass substrate onto which the FFS liquid crystal was drop-coated via the sealant for liquid crystal display elements, and the two glass substrates were bonded under a reduced pressure of 5 Pa using a vacuum bonding device to obtain a cell. Regarding the obtained cell, the seal pattern portion was irradiated with ultraviolet rays of 100 mW / cm 2 for 30 seconds using a metal halide lamp, and then heated at 120 °C for 1 hour to cure the sealant for liquid crystal display elements, thereby fabricating a liquid crystal element. Regarding the obtained liquid crystal element, using a polarizing microscope (manufactured by Keyence Corporation, "VHX-5000"), the liquid crystal alignment disorder (display unevenness) was confirmed, and the low liquid crystal contamination property was evaluated according to the following criteria. ◎: When no display unevenness was confirmed in the liquid crystal display element ○: When a slightly faint display unevenness was confirmed near the seal pattern (peripheral portion) △: When a distinct dark display unevenness was confirmed in the peripheral portion ×: When the distinct dark display unevenness spread not only to the peripheral portion but also to the central portion Note that liquid crystal display elements evaluated as "◎" or "○" are at a level with no problem in practical use, liquid crystal display elements evaluated as "△" may be problematic depending on the display design, and liquid crystal display elements evaluated as "×" are at a level that cannot withstand practical use.

[0062]

Table 1

[0063]

Table 2

Industrial Applicability

[0064] According to the present invention, it is possible to provide a sealant for liquid crystal display elements that is excellent in adhesiveness to an alignment film, moisture permeation prevention property, and low liquid crystal contamination property. Further, according to the present invention, it is possible to provide a liquid crystal display element using the sealant for liquid crystal display elements.

Claims

1. A sealant for liquid crystal display elements, comprising a curable resin, a photo radical polymerization initiator, and a thermosetting agent, wherein the curable resin includes a (meth)acrylic compound having no epoxy group and an epoxy compound, the (meth)acrylic compound includes a compound having one (meth)acryloyloxy group in one molecule and a compound having three or more (meth)acryloyloxy groups in one molecule, and the compound having one (meth)acryloyloxy group in one molecule has a carbon ring and no heterocyclic ring.

2. The sealant for liquid crystal display elements according to Claim 1, wherein the compound having one (meth)acryloyloxy group in one molecule has a structure in which the (meth)acryloyloxy group is directly bonded to the carbon ring.

3. The sealant for liquid crystal display elements according to Claim 1 or 2, wherein the content of the compound having one (meth)acryloyloxy group in one molecule in 100 parts by mass of the curable resin is 5 parts by mass or more and 15 parts by mass or less.

4. The sealant for liquid crystal display elements according to Claim 1 or 2, wherein the content ratio of the compound having one (meth)acryloyloxy group in one molecule to 100 parts by mass of the compound having three or more (meth)acryloyloxy groups in one molecule is 100 parts by mass or more and 150 parts by mass or less.

5. The sealant for liquid crystal display elements according to Claim 1 or 2, further comprising a filler.

6. The sealant for liquid crystal display elements according to Claim 1 or 2, further comprising a silane coupling agent.

7. A liquid crystal display element including a cured product of the sealant for liquid crystal display elements according to Claim 1 or 2.

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