JP6837781B2 - Liquid crystal sealant and liquid crystal display cell using it - Google Patents

Description

The present invention relates to a liquid crystal sealant used in a liquid crystal dropping method. More specifically, the present invention relates to a liquid crystal sealant for a liquid crystal dropping method, which can be applied to a flexible display or a curved display, and is also excellent in general characteristics such as low liquid crystal contamination and adhesive strength.

With the increase in size of liquid crystal display cells in recent years, a so-called liquid crystal dropping method with higher mass productivity has been proposed as a method for manufacturing a liquid crystal display cell (see Patent Documents 1 and 2). Specifically, it is a method for manufacturing a liquid crystal display cell in which a liquid crystal is sealed by dropping a liquid crystal on the inside of a weir of a liquid crystal sealant formed on one substrate and then laminating the other substrate.

However, in the liquid crystal dropping method, since the liquid crystal sealant in an uncured state comes into contact with the liquid crystal, the components of the liquid crystal sealant dissolve (elute) in the liquid crystal at that time, lowering the resistance value of the liquid crystal and near the seal. There is a problem that display defects occur.

In order to solve this problem, a liquid crystal sealant for the liquid crystal dropping method is currently used in combination with light and heat and has been put into practical use (Patent Documents 3 and 4). The liquid crystal dropping method using this liquid crystal sealant is characterized in that the liquid crystal sealant sandwiched between the substrates is irradiated with light to be first cured, and then heated to be secondarily cured. According to this method, the uncured liquid crystal sealant can be rapidly cured by light, and the dissolution (elution) of the liquid crystal sealant component in the liquid crystal can be suppressed. Furthermore, photo-curing alone causes a problem of insufficient adhesive strength due to curing shrinkage during photo-curing, but the photo-heating combined type has the advantage that stress relaxation effect can be obtained by secondary curing by heating, and such a problem can be solved. Has.
With the practical application of this photothermally curable liquid crystal sealant for the liquid crystal dropping method, the liquid crystal dropping method has become a generally used method.

More recently, in the field of liquid crystal displays, the development of flexible displays and displays having a curved shape has been progressing. As the substrate used for such a display, a flexible substrate such as a plastic film is used instead of a rigid substrate such as conventional glass (Patent Document 5).
Against this background, the liquid crystal sealant for the liquid crystal dropping method is also required to have a property of following the deflection of the substrate, that is, being flexible even after curing.

Conventionally, from the viewpoint of improving the adhesive strength, a liquid crystal sealant for a liquid crystal dropping method having flexibility has been developed (Patent Document 6). However, a liquid crystal sealant for a liquid crystal dropping method having sufficient performance for adapting to the above-mentioned flexible substrate has not yet been realized.

Japanese Unexamined Patent Publication No. 63-179323 Japanese Unexamined Patent Publication No. 10-239694 Japanese Patent No. 3583326 Japanese Unexamined Patent Publication No. 2004-61925 Japanese Unexamined Patent Publication No. 2012-238005 Japanese Unexamined Patent Publication No. 2016-24240

The present invention proposes a liquid crystal sealant for a liquid crystal dropping method, which can be applied to a flexible display or a curved display, and is also excellent in general characteristics such as low liquid crystal contamination and adhesive strength.

As a result of diligent studies, the present inventors have found that a cured product having two or more glass transition points is excellent in liquid crystal contamination and adhesiveness, and have completed the present invention.
That is, the present invention relates to the following [1] to [14].
In addition, in this specification, when "(meth) acrylic" is described, it means "acrylic" and / or "methacryl". Further, the "liquid crystal sealant for the liquid crystal dropping method" may be simply described as "liquid crystal sealant".
The superscript RTM means a registered trademark.

That is, the present invention
[1] A liquid crystal sealant for a liquid crystal dropping method, which contains (A) a curable compound and (B) a liquid rubber and has two or more glass transition points of a cured product.
[2] The liquid crystal sealant for the liquid crystal dropping method according to the preceding item [1], wherein one of the glass transition points is 10 ° C. or lower and one is 40 ° C. or higher.
[3] The liquid crystal sealant for the liquid crystal dropping method according to the above item [1] or [2], which further contains (C) a thermal radical polymerization initiator.
[4] The component (A) curable compound, (A-1) (meth) liquid crystal dropping process for a liquid crystal sealing material according to any one of items [1] to [3] is an acrylic compound,
[5] In addition, (D) containing an organic filler items [1] to the liquid crystal dropping process for a liquid crystal sealing material according to any one of [4],
[6] The liquid crystal according to the preceding item [5], wherein the component (D) is one or more organic fillers selected from the group consisting of urethane fine particles, acrylic fine particles, styrene fine particles, styrene olefin fine particles, and silicone fine particles. Liquid crystal sealant for dripping method,
[7] In addition, (E) items [1] containing an inorganic filler to a liquid crystal dropping process for a liquid crystal sealing material according to any one of [6],
[8] In addition, (F) a silane coupling agent items [1] to the liquid crystal dropping process for a liquid crystal sealing material according to any one of [7],
[9] in said component (A), (A-2 ) containing an epoxy compound items [1] to the liquid crystal dropping process for a liquid crystal sealing material according to any one of [8],
[10] Furthermore, (H) containing a thermosetting agent items [1] to the liquid crystal dropping process for a liquid crystal sealing material according to any one of [9],
[11] The liquid crystal sealant for the liquid crystal dropping method according to the previous item [10], wherein the component (H) is an organic acid hydrazide compound.
[12] Furthermore, (I) contains a photo-radical polymerization initiator items [1] to [11] a liquid crystal dropping process for a liquid crystal sealing material according to any one of,
[13] In a liquid crystal display cell composed of two substrates, a liquid crystal is placed inside a weir of a liquid crystal sealant for a liquid crystal dropping method according to any one of claims 1 to 12 formed on one of the substrates. 2.
[14] A liquid crystal display cell sealed with a cured product obtained by curing the liquid crystal sealant for the liquid crystal dropping method according to any one of the preceding items [1] to [12].
Regarding.

The present invention proposes a liquid crystal sealant for a liquid crystal dropping method, which can be applied to a flexible display or a curved display, and is also excellent in general characteristics such as low liquid crystal contamination and adhesive strength.

[(A) Curable compound]
The liquid crystal sealant of the present invention contains (A) a curable compound (hereinafter, also simply referred to as component (A)).
The component (A) is not particularly limited as long as it polymerizes by light or heat, and is, for example, a curable compound having a (meth) acryloyl group, a curable compound having an epoxy group, a compound having an oxetane group, and an allyl group. Can be mentioned.

[(A-1) (meth) acrylic compound]
As the (A) curable compound, it is preferable that the (A-1) (meth) acrylic compound is contained. Examples of the component (A-1) include a (meth) acrylic ester compound and an epoxy (meth) acrylate compound.
Specific examples of the (meth) acrylic ester compound include N-acryloyloxyethyl hexahydrophthalimide, acryloylmorpholine, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and cyclohexane-1,4-dimethanol. mono (meth) acrylate, tetrahydrofuran Le furyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyl polyethoxy (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, o- phenylphenol monoethoxy (Meta) acrylate, o-phenylphenol polyethoxy (meth) acrylate, p-cumylphenoxyethyl (meth) acrylate, isobonyl (meth) acrylate, tribromophenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) Acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol Di (meth) acrylate, tricyclodecanedimethanol (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A polypropoxydi (meth) acrylate, bisphenol F polyethoxydi (meth) acrylate, ethylene glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, tris (acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) Acrylate, Tripentaerythritol Penta (meth) Acrylate, Trimethylol Propanetri (Meta) Acrylate, Trimethylol Propanepolyethoxytri (Meta) Acrylate, Ditrimethylol Propanetetra (Meta) Acrylate, Neopentyl Glycol and Hydroxy Pivalic Acid Ester Di Examples thereof include monomers such as acrylate and diacrylate of ε-caprolactone adduct of ester of neopentyl glycol and hydroxypivalic acid. Preferred examples include N-acryloyloxyethyl hexahydrophthalimide, phenoxyethyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate.
The epoxy (meth) acrylate compound is obtained by a known method by reacting the epoxy compound with (meth) acrylic acid. The epoxy compound as a raw material is not particularly limited, but a bifunctional or higher functional epoxy compound is preferable, and for example, resorcindiglycidyl ether, bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound. , Phenol novolac type epoxy compound, cresol novolac type epoxy compound, bisphenol A novolak type epoxy compound, bisphenol F novolac type epoxy compound, alicyclic epoxy compound, aliphatic chain epoxy compound, glycidyl ester type epoxy compound, glycidylamine type epoxy Compounds, hydant-in type epoxy compounds, isocyanurate type epoxy compounds, phenol novolac type epoxy compounds having a triphenol methane skeleton, diglycidyl ethers of bifunctional phenols such as catechol and resorcinol, diglycidyl ethers of bifunctional alcohols Examples thereof include compounds, their halides, and hydrogenated products. Of these, bisphenol A type epoxy resin and resorcinol diglycidyl ether are preferable from the viewpoint of liquid crystal contamination. Further, the ratio of the epoxy group to the (meth) acryloyl group is not limited, and is appropriately selected from the viewpoint of process compatibility and liquid crystal contamination.
The component (A-1) may be used alone or in combination of two or more. When the component (A-1) is used in the liquid crystal sealant of the present invention, it is usually 10 to 80% by mass, preferably 20 to 70% by mass, based on the total amount of the liquid crystal sealant.

[(A-2) Epoxy compound]
It is preferable that the component (A) further contains the epoxy compound (A-2). The component (A-2) is not particularly limited, but a bifunctional or higher functional epoxy compound is preferable, and for example, resorcindiglycidyl ether, bisphenol A type epoxy compound, bisphenol F type epoxy compound, and bisphenol S type epoxy. Compounds, phenol novolac type epoxy compounds, cresol novolac type epoxy compounds, bisphenol A novolak type epoxy compounds, bisphenol F novolac type epoxy compounds, alicyclic epoxy compounds, aliphatic chain epoxy compounds, glycidyl ester type epoxy compounds, glycidylamine type Epoxy compounds, hydantin type epoxy compounds, isocyanurate type epoxy compounds, phenol novolac type epoxy compounds having a triphenol methane skeleton, diglycidyl ether compounds of bifunctional phenols such as catechol and resorcinol, diglycidyl of bifunctional alcohols Examples thereof include ether compounds, their halides, and hydrogenated products. Of these, bisphenol A type epoxy resin and resorcinol diglycidyl ether are preferable from the viewpoint of liquid crystal contamination.
The component (A-2) may be used alone or in combination of two or more. When the component (A-2) is used in the liquid crystal sealant of the present invention, it is usually 5 to 50% by mass, preferably 5 to 30% by mass, based on the total amount of the liquid crystal sealant.

[(B) Liquid rubber]
The present invention contains (B) liquid rubber (hereinafter, also simply referred to as component (B)).
The liquid rubber is a rubber compound that is liquid at room temperature, and examples thereof include polybutadiene and polyisoprene. Obtain TE-2000 (manufactured by Nippon Soda Co., Ltd.), TEAI-1000 (manufactured by Nippon Soda Co., Ltd.), UC-102 (manufactured by Kuraray Co., Ltd.), UC-203 (manufactured by Kuraray Co., Ltd.), etc. from the market. Can be done.
The component (B) may be used alone or in combination of two or more. In the liquid crystal sealant of the present invention, the content of the component (B) is usually 5 to 80% by mass, preferably 20 to 80% by mass, based on the total amount of the liquid crystal sealant.

[Glass transition temperature of cured product]
The cured product of the liquid crystal sealant of the present invention has two or more glass transition points (temperatures) measured by the DMA method. The presence of two or more glass transition points means that the component (A) and the component (B) are present in a non-uniform state, and as a result, the followability to the flexible substrate is increased.
Further, among the above glass transition points, one is preferably 10 ° C. or lower and one is preferably 40 ° C. or higher, and more preferably one is 0 ° C. or lower and one is 100 ° C. or higher.
The DMA measurement conditions are, for example, using a dynamic viscoelasticity measuring device (DMS-6100: manufactured by SII Nanotechnology Co., Ltd.) under the conditions of a frequency of 10 Hz and a temperature rise temperature of 3 ° C./min in a tensile mode. Measure. The loss coefficient Tan δ can be obtained from the ratio of the loss elastic modulus to the storage elastic modulus (JIS K 7244-1). The temperature at which the obtained loss coefficient Tan δ became the maximum value was defined as the glass transition temperature.

[(C) Thermal Radical Polymerization Initiator]
The liquid crystal sealant of the present invention may contain a thermal radical polymerization initiator as the component (C). The thermal radical polymerization initiator is not particularly limited as long as it is a compound that generates radicals by heating and initiates a chain polymerization reaction, but is not limited to organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol and the like. Benzopinacol is preferably used. For example, as organic peroxides, Kayamec ^RTM A, M, R, L, LH, SP-30C, Parkadox CH-50L, BC-FF, Cadox B-40ES, Parkadox 14, Trigonox ^RTM 22-70E, 23-C70, 121, 121-50E, 121-LS50E, 21-LS50E, 42, 42LS, Kayaester ^RTM P-70, TMPO-70, CND-C70, OO-50E, AN, Kayabutyl ^RTM B, Parkadox 16 , Kayacarbonate ^RTM BIC-75, AIC-75 (manufactured by ^{Kayaku Akzo Corporation), Permec RTM} N, H, S, F, D, G, Perhexa ^RTM H, HC, PATMH, C, V, 22, MC, Pakyua ^RTM AH, AL, HB, Perbutyl ^{RTM H, C, ND, L} , Percumyl ^RTM H, D, PEROYL ^RTM IB, IPP, Perocta ^RTM ND (manufactured by NOF Corporation) and the like are commercially available. As the azo compound, VA-044, V-070, VPE-0201, VSP-1001 (manufactured by Wako Pure Chemical Industries, Ltd.) and the like are available as commercial products. In this specification, the superscript RTM means a registered trademark.

A preferred component (C) is a thermal radical polymerization initiator that does not have an oxygen-oxygen bond (-O-O-) or a nitrogen-nitrogen bond (-N = N-) in the molecule. A thermal radical polymerization initiator having an oxygen-oxygen bond (-O-O-) or a nitrogen-nitrogen bond (-N = N-) in the molecule emits a large amount of oxygen or nitrogen when a radical is generated, and thus is a liquid crystal sealant. There is a risk that it will harden with air bubbles left inside, and properties such as adhesive strength will deteriorate. Benzopinacol-based thermal radical polymerization initiators (including chemically modified benzopinacol) are particularly suitable. Specifically, benzopinacol, 1,2-dimethoxy-1,1,2,2-tetraphenylethane, 1,2-diethoxy-1,1,2,2-tetraphenylethane, 1,2-diphenoxy- 1,1,2,2-tetraphenylethane, 1,2-dimethoxy-1,1,2,2-tetra (4-methylphenyl) ethane, 1,2-diphenoxy-1,1,2,2-tetra (4-methoxyphenyl) ethane, 1,2-bis (trimethylsiloxy) -1,1,2,2-tetraphenylethane, 1,2-bis (triethylsiloxy) -1,1,2,2-tetraphenyl Etan, 1,2-bis (t-butyldimethylsiloxy) -1,1,2,2-tetraphenylethane, 1-hydroxy-2-trimethylsiloxy-1,1,2,2-tetraphenylethane, 1- Hydroxy-2-triethylsiloxy-1,1,2,2-tetraphenylethane, 1-hydroxy-2-t-butyldimethylsiloxy-1,1,2,2-tetraphenylethane and the like can be mentioned, preferably. 1-Hydroxy-2-trimethylsiloxy-1,1,2,2-tetraphenylethane, 1-hydroxy-2-triethylsiloxy-1,1,2,2-tetraphenylethane, 1-hydroxy-2-t- Butyldimethylsiloxy-1,1,2,2-tetraphenylethane, 1,2-bis (trimethylsiloxy) -1,1,2,2-tetraphenylethane, more preferably 1-hydroxy-2-trimethyl. Syroxy-1,1,2,2-tetraphenylethane, 1,2-bis (trimethylsiloxy) -1,1,2,2-tetraphenylethane, and particularly preferably 1,2-bis (trimethylsiloxy). -1,1,2,2-tetraphenylethane.
The above benzopinacol is commercially available from Tokyo Chemical Industry Co., Ltd., Wako Pure Chemical Industries, Ltd., etc. Further, etherification of the hydroxy group of benzopinacol can be easily synthesized by a well-known method. Further, silyl etherification of the hydroxy group of benzopinacol can be obtained by synthesizing the corresponding benzopinacol and various silylating agents by heating under a basic catalyst such as pyridine. Examples of the silylating agent include trimethylchlorosilane (TMCS), hexamethyldisilazane (HMDS), N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA), which are generally known trimethylsilylating agents, and triethylsilylating agent. Examples of triethylchlorosilane (TECS) and t-butyldimethylsilylating agent include t-butylmethylsilane (TBMS). These reagents can be easily obtained from the market such as silicon derivative manufacturers. The reaction amount of the silylating agent is preferably 1.0 to 5.0 times by mole with respect to 1 mol of the hydroxy group of the target compound. More preferably, it is 1.5 to 3.0 times the molar amount. If it is less than 1.0 times the molar amount, the reaction efficiency is poor and the reaction time becomes long, which promotes thermal decomposition. If it is more than 5.0 times the molar amount, separation will be poor at the time of recovery and purification will be difficult.

It is preferable that the component (C) has a fine particle size and is uniformly dispersed. The average particle size is preferably 5 μm or less, more preferably 3 μm or less, because if it is too large, it causes defects such as poor formation of gaps when the upper and lower glass substrates are bonded together when manufacturing a liquid crystal display cell having a narrow gap. .. Further, although it may be made infinitely fine, the lower limit is usually about 0.1 μm. The particle size can be measured by a laser diffraction / scattering type particle size distribution measuring device (dry type) (manufactured by Seishin Enterprise Co., Ltd .; LMS-30).

The content of the component (C) is preferably 0.0001 to 10% by mass, more preferably 0.0005 to 5% by mass, and 0.001 to 3% by mass in the total amount of the liquid crystal sealant. Is particularly preferable.

[(D) Organic filler]
The liquid crystal sealant of the present invention may contain an organic filler as the component (D). Examples of the organic filler include urethane fine particles, acrylic fine particles, styrene fine particles, styrene olefin fine particles, and silicone fine particles. The silicone fine particles are preferably KMP-594, KMP-597, KMP-598 (manufactured by Shin-Etsu Chemical Co., Ltd.), Trefil ^RTM E-5500, 9701, EP-2001 (manufactured by Toray Dow Corning), and the urethane fine particles are JB-. 800T, HB-800BK (Negami Kogyo Co., Ltd.), Lavalon ^RTM T320C, T331C, SJ4400, SJ5400, SJ6400, SJ4300C, SJ5300C, SJ6300C (manufactured by Mitsubishi Chemical) are preferable as styrene fine particles, and Septon ^RTM SEPS2004, as styrene olefin fine particles. SEPS2063 is preferable.
These organic fillers may be used alone or in combination of two or more. Further, a core-shell structure may be formed by using two or more types. Of these, acrylic fine particles and silicone fine particles are preferable.
When the acrylic fine particles are used, it is preferably an acrylic rubber having a core-shell structure composed of two types of acrylic rubber, and particularly preferably the core layer is n-butyl acrylate and the shell layer is methyl methacrylate. It is sold by Aica Kogyo Co., Ltd. as ^{Zephyac RTM F-351.}
Examples of the silicone fine particles include organopolysiloxane crosslinked powder and linear dimethylpolysiloxane crosslinked powder. Further, examples of the composite silicone rubber include those in which the surface of the silicone rubber is coated with a silicone resin (for example, polyorganosylsesquioxane resin). Of these fine particles, particularly preferable are silicone rubber of linear dimethylpolysiloxane crosslinked powder or composite silicone rubber fine particles of silicone resin-coated linear dimethylpolysiloxane crosslinked powder. These may be used alone or in combination of two or more. Further, preferably, the shape of the rubber powder is a spherical shape with less thickening of viscosity after addition. When the component (D) is used in the liquid crystal sealant of the present invention, it is usually 5 to 50% by mass, preferably 5 to 40% by mass, based on the total amount of the liquid crystal sealant.

[(E) Inorganic filler]
The liquid crystal sealant of the present invention may contain an inorganic filler as the component (E). Examples of the inorganic filler contained in the present invention include silica, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, and aluminum hydroxide. , Magnesium hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, etc., preferably molten silica, crystalline silica, silicon nitride, nitrided Examples thereof include boron, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate and aluminum silicate, but silica, alumina and talc are more preferable. Two or more kinds of these inorganic fillers may be mixed and used.
If the average particle size of the inorganic filler is too large, it may cause defects such as difficulty in forming a gap when the upper and lower glass substrates are bonded together when manufacturing a liquid crystal cell having a narrow gap. Therefore, 2000 nm or less is appropriate, preferably 1000 nm or less. , More preferably 300 nm or less. The lower limit is preferably about 10 nm, and more preferably about 100 nm. The particle size can be measured by a laser diffraction / scattering type particle size distribution measuring device (dry type) (manufactured by Seishin Enterprise Co., Ltd .; LMS-30).
When an inorganic filler is used in the liquid crystal sealant of the present invention, it is usually 5 to 50% by mass, preferably 5 to 40% by mass, based on the total amount of the liquid crystal sealant. When the content of the inorganic filler is lower than 5% by mass, the adhesive strength to the glass substrate is lowered, and the moisture resistance reliability is also poor, so that the adhesive strength after moisture absorption may be greatly reduced. Further, when the content of the inorganic filler is more than 50% by mass, the filler content is too large, so that the filler is hard to be crushed and the gap of the liquid crystal cell cannot be formed.

[(F) Silane coupling agent]
In the liquid crystal sealant of the present invention, a silane coupling agent can be added as a component (F) to improve the adhesive strength and moisture resistance.
The component (F) includes 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltri. Methoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyltrimethoxysilane, 3- Aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N- (2- (vinylbenzylamino) ethyl) 3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, Examples thereof include 3-chloropropylmethyldimethoxysilane and 3-chloropropyltrimethoxysilane. Since these silane coupling agents are sold by Shin-Etsu Chemical Co., Ltd. as KBM series, KBE series, etc., they are easily available from the market. When the component (F) is used in the liquid crystal sealant of the present invention, 0.05 to 3% by mass is preferable in the total amount of the liquid crystal sealant.

[(H) Thermosetting agent]
The liquid crystal sealant of the present invention contains a thermosetting agent as a component (H). The component (H) means a thermosetting agent that does not generate radicals by heating, unlike the above-mentioned component (B) thermal radical polymerization initiator. Specifically, it reacts nucleophilically with an unshared electron pair or an intramolecular anion, and examples thereof include polyvalent amines, polyphenols, and organic acid hydrazide compounds. However, it is not limited to these. Of these, organic acid hydrazide compounds are particularly preferably used. For example, the aromatic hydrazides terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 2,6-pyridinedihydrazide, 1,2,4-benzenetrihydrazide, 1,4,5,8-naphthoic acid. Examples thereof include tetrahydrazide and tetrahydrazide pyromellitic acid. In the case of an aliphatic hydrazide compound, for example, formhydrazide, acetohydrazide, propionate hydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutarate dihydrazide, adipic acid dihydrazide, pimelliate dihydrazide, sebacic acid dihydrazide. 1,4-Cyclohexanedihydrazide, tartrate dihydrazide, malic acid dihydrazide, iminodiacetic acid dihydrazide, N, N'-hexamethylenebis semi-carbazide, citrate trihydrazide, nitriloacetate trihydrazide, cyclohexanetricarboxylic acid trihydrazide, 1,3-bis ( Tris (1-hydrazinocarbonylmethyl), a dihydrazide compound having a hydrandin skeleton such as hydradinocarbonoethyl) -5-isopropylhydranthin, preferably a valine hydrantin skeleton (a skeleton in which the carbon atom of the hydrandin ring is replaced with an isopropyl group). Isocyanurate, Tris (2-hydrazinocarbonylethyl) isocyanurate, Tris (1-hydrazinocarbonylethyl) isocyanurate, Tris (3-hydrazinocarbonylpropyl) isocyanurate, Bis (2-hydrazinocarbonylethyl) isocyanurate Etc. can be given. From the balance of curing reactivity and potential, preferably isophthalic acid dihydrazide, malonic acid dihydrazide, adipate dihydrazide, tris (1-hydrazinocarbonylmethyl) isocyanurate, tris (1-hydrazinocarbonylethyl) isocyanurate, tris (1-hydrazinocarbonylethyl) isocyanurate, tris (1-hydrazinocarbonylethyl) isocyanurate, tris (1-hydrazinocarbonylethyl) isocyanurate 2-Hydradinocarbonylethyl) isocyanurate, tris (3-hydrazinocarbonylpropyl) isocyanurate, and particularly preferably tris (2-hydrazinocarbonylethyl) isocyanurate.
The component (H) may be used alone or in combination of two or more. When the component (H) is used in the liquid crystal sealant of the present invention, it is usually 0.1 to 10% by mass, preferably 1 to 5% by mass, based on the total amount of the liquid crystal sealant.

[(I) Photoradical polymerization initiator]
The liquid crystal sealant of the present invention may contain a photoradical polymerization initiator as the component (I). The photoradical polymerization initiator is not particularly limited as long as it is a compound that generates radicals or acids by irradiation with ultraviolet rays or visible light to initiate a chain polymerization reaction, and is, for example, benzyldimethylketal or 1-hydroxycyclohexylphenylketone. , Diethylthioxanthone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propane, 2,4,6- Examples thereof include trimethylbenzoyldiphenylphosphine oxide, camphorquinone, 9-fluorenone, diphenyldisulfide and the like. Specifically, IRGACURE ^RTM 651, 184, 2959, 127, 907, 369, 379EG, 819, 784, 754, 500, OXE01, OXE02, DAROCURE ^RTM 1173, LUCIRIN ^RTM TPO (all manufactured by BASF), Sakeall ^RTM Z, BZ, BEE, BIP, BBI (all manufactured by Seiko Kagaku Co., Ltd.) and the like can be mentioned.
Further, from the viewpoint of liquid crystal contamination, it is preferable to use one having a (meth) acrylic group in the molecule, for example, 2-methacryloyloxyethyl isocyanate and 1- [4- (2-hydroxyethoxy) -phenyl]-. The reaction product with 2-hydroxy-2methyl-1-propane-1-one is preferably used. This compound can be produced and obtained by the method described in International Publication No. 2006/027982.
When the component (I) is used in the liquid crystal sealant of the present invention, it is usually 0.001 to 3% by mass, preferably 0.002 to 2% by mass, based on the total amount of the liquid crystal sealant.

The liquid crystal sealant of the present invention may further contain additives such as a curing accelerator such as an organic acid or imidazole, a radical polymerization inhibitor, a pigment, a leveling agent, a defoaming agent, and a solvent, if necessary. ..

[Curing accelerator]
Examples of the curing accelerator include organic acids and imidazoles.
Examples of the organic acid include an organic carboxylic acid and an organic phosphoric acid, and an organic carboxylic acid is preferable. Specifically, aromatic carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, benzophenonetetracarboxylic acid, and flangecarboxylic acid, succinic acid, adipic acid, dodecanedioic acid, sebacic acid, and thiodipropionic acid. , Cyclohexanedicarboxylic acid, tris (2-carboxymethyl) isocyanurate, tris (2-carboxyethyl) isocyanurate, tris (2-carboxypropyl) isocyanurate, bis (2-carboxyethyl) isocyanurate and the like. ..
Examples of the imidazole compound include 2-methylimidazole, 2-phenylimidazole, 2-undecyl imidazole, 2-heptadecyl imidazole, 2-phenyl-4-methyl imidazole, 1-benzyl-2-phenyl imidazole and 1-benzyl. -2-Methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 2,4-diamino-6 (2'-methylimidazole (1') )) Ethyl-s-triazine, 2,4-diamino-6 (2'-undecylimidazole (1')) ethyl-s-triazine, 2,4-diamino-6 (2'-ethyl-4-methylimidazole) (1')) Ethyl-s-triazine, 2,4-diamino-6 (2'-methylimidazole (1')) ethyl-s-triazine isocyanuric acid adduct, 2-methylimidazole isocyanuric acid 2: 3 Additives, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-3,5-dihydroxymethylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 1-cyanoethyl-2-phenyl-3,5- Examples thereof include dicyanoethoxymethylimidazole.
When a curing accelerator is used in the liquid crystal sealant of the present invention, it is usually 0.1 to 10% by mass, preferably 1 to 5% by mass, based on the total amount of the liquid crystal sealant.

[Radical polymerization inhibitor]
The radical polymerization inhibitor is not particularly limited as long as it is a compound that reacts with radicals generated from a photoradical polymerization initiator, a thermal radical polymerization initiator, or the like to prevent polymerization, and is not particularly limited. Hindered radical type, nitroso type and the like can be used. Specifically, naphthoquinone, 2-hydroxynaphthoquinone, 2-methylnaphthoquinone, 2-methoxynaphthoquinone, 2,2,6,6 - tetramethylpiperidin-1-oxyl, 2,2,6,6 - tetramethyl-4. -Hydroxypiperidine-1-oxyl, 2,2,6,6 - tetramethyl-4-methoxypiperidine-1-oxyl, 2,2,6,6 - tetramethyl-4-phenoxypiperidine-1-oxyl, hydroquinone, 2-Methylhydroquinone, 2-methoxyhydroquinone, parabenzoquinone, butylated hydroxyanisol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butylcresol, stearyl-β- (3) , 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-thiobis ( 3-methyl-6-t-butylphenol) ), 4,4'-Butylidenebis (3-methyl-6-t-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-t-butyl-4-hydroxy-5-) Methylphenyl) propionyloxy] ethyl], 2,4,8,10-tetraoxaspiro [5,5] undecane, tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-) Hydroxyphenylpropionate) Methyl ] , 1,3,5-tris (3', 5'-di-t-butyl-4'-hydroxybenzyl) -sec-triazine-2,4,6- (1H, 3H, 5H) Trion, paramethoxyphenol, 4-methoxy-1-naphthol, thiodiphenylamine, aluminum salt of N-nitrosophenylhydroxyamine, trade name Adecastab LA-81, trade name Adecastab LA-82 (manufactured by Adeca Co., Ltd.), etc. However, it is not limited to these. Of these, naphthoquinone-based, hydroquinone-based, and nitroso-based piperazine-based radical polymerization inhibitors are preferable, and naphthoquinone, 2-hydroxynaphthoquinone, hydroquinone, 2,6-di-t-butyl-P-cresol, and Polystop 7300P (Hakuto Co., Ltd.) (Manufactured by a company) is more preferable, and Polystop 7300P (manufactured by Hakuto Co., Ltd.) is most preferable.
The content of the radical polymerization inhibitor is preferably 0.0001 to 1% by mass, more preferably 0.001 to 0.5% by mass, and 0.01 to 0.2% by mass, based on the total amount of the liquid crystal sealant of the present invention. Is particularly preferable.

As an example of the method for obtaining the liquid crystal sealant of the present invention, there is the following method. First, the component (A),, if necessary, the component (C), the component (G), and the component (I) are melted by heating. Then, after cooling to room temperature, the component (B), the component (D), the component (E), the component (F), the component (H), the defoaming agent, the leveling agent, the solvent and the like are added as necessary, and the known components The liquid crystal sealant of the present invention can be produced by uniformly mixing with a mixing device such as a three-roll, sand mill, ball mill or the like and filtering with a metal mesh.

The liquid crystal display cell of the present invention is formed by arranging a pair of substrates having predetermined electrodes formed on the substrates facing each other at predetermined intervals, sealing the periphery with the liquid crystal sealant of the present invention, and enclosing the liquid crystal in the gap. is there. The type of liquid crystal to be enclosed is not particularly limited. Here, the substrate is composed of a combination of substrates made of glass, quartz, plastic, silicon, etc., which has light transmission in at least one of them. As a manufacturing method thereof, after adding a spacer (gap control material) such as glass fiber to the liquid crystal sealant of the present invention, the liquid crystal sealant is applied to one of the pair of substrates using a dispenser, a screen printing device or the like. After that, if necessary, temporary curing is performed at 80 to 120 ° C. After that, the liquid crystal is dropped inside the weir of the liquid crystal sealant, and the other glass substrate is overlapped in vacuum to create a gap. After forming the gap, the liquid crystal display cell of the present invention can be obtained by curing at 90 to 130 ° C. for 1 to 2 hours. When used as a combined type with light and heat, the liquid crystal sealant portion is irradiated with ultraviolet rays by an ultraviolet irradiator to be photocured. UV irradiation dose is preferably 500~6000mJ / cm ^2, more preferably the dose of 1000~4000mJ / cm ² is preferred. Then, if necessary, the liquid crystal display cell of the present invention can be obtained by curing at 90 to 130 ° C. for 1 to 2 hours. The liquid crystal display cell of the present invention thus obtained is excellent in adhesiveness and moisture resistance and reliability without display defects due to liquid crystal contamination. Examples of the spacer include glass fiber, silica beads, polymer beads and the like. Its diameter varies depending on the purpose, but is usually 2 to 8 μm, preferably 4 to 7 μm. The amount used is usually 0.1 to 4 parts by mass, preferably 0.5 to 2 parts by mass, and more preferably 0.9 to 1.5 parts by mass with respect to 100 parts by mass of the liquid crystal sealant of the present invention. is there.

The liquid crystal sealant of the present invention has very good thermosetting property, cures quickly in the heating step in the liquid crystal dropping method, and the cured product has excellent adhesiveness and good liquid crystal contamination. By using the liquid crystal sealant of No. 1, it is possible to produce a liquid crystal display cell having excellent reliability.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples. Unless otherwise specified, "part" and "%" in the text are based on mass.

[Synthesis Example 1]
[Synthesis of all acrylates of bisphenol A type epoxy compounds]
282.5 g of bisphenol A type epoxy compound (product name: YD-8125, manufactured by Nippon Steel Chemical Co., Ltd.) was dissolved in 266.8 g of toluene, 0.8 g of dibutylhydroxytoluene was added as a polymerization inhibitor, and the temperature was raised to 60 ° C. It was warm. Then, 117.5 g of acrylic acid equivalent to 100% of the epoxy group was added, the temperature was further raised to 80 ° C., 0.6 g of trimethylammonium chloride as a reaction catalyst was added thereto, and the mixture was stirred at 98 ° C. for about 30 hours. A reaction solution was obtained. This reaction solution was washed with water and toluene was distilled off to obtain 395 g of an acrylic esterified product of the target bisphenol A type epoxy compound.

[Synthesis Example 2]
[Synthesis of half-acrylic compound of bisphenol A type epoxy compound]
836 g of bisphenol A type epoxy resin (RE-310S manufactured by Nippon Kayaku Co., Ltd.) was dissolved in 1000 g of toluene, 3 g of dibutylhydroxytoluene was added as a polymerization inhibitor, and the temperature was raised to 60 ° C. Then, 165 g of acrylic acid equivalent to 50% of the epoxy group (manufactured by Nippon Shokubai Co., Ltd.) and 5 g of a 40% aqueous solution of tripropylammonium hydroxide as a reaction catalyst were added, and the mixture was stirred at 98 ° C. for about 10 hours to prepare a reaction solution. Got The reaction solution was washed with water and toluene was distilled off to obtain 995 g of the target partially acrylicized bisphenol A type epoxy resin.

[Synthesis Example 3]
[Synthesis of polyester type urethane acrylate]
Polymethylpentanediol adipate (manufactured by Kuraray Co., Ltd .: P-3010, hydroxyl value: 37.9 mg, KOH / g) was added as a polyol compound to a reactor equipped with a reflux condenser, a stirrer, a thermometer, and a temperature controller. 2961 g (1.00 mol), 289 g (1.30 mol) of isophorone diisocyanate as an isocyanate compound, and 0.5 g of tin octylate as a urethanization reaction catalyst were added and reacted at 80 ° C. for 8 hours. Next, 1.7 g of 4-methoxyphenol as a polymerization inhibitor and 71 g (0.61 mol) of 2-hydroxyethyl acrylate manufactured by Osaka Organic Chemical Industry Co., Ltd. as a (meth) acrylate compound having at least one hydroxyl group. The mixture was added and reacted at 80 ° C., and a polyurethane compound was obtained when the NCO content was 0.1% or less as the end point of the reaction.

[Preparation of Examples 1 to 4 and Comparative Examples 1 and 2]
In the ratios shown in Table 1 below, curable compounds (component (A)) such as the compound synthesized in Synthesis Example 1, Synthesis Example 2, and the compound synthesized in Synthesis Example 3, and liquid rubber (component (B)) are added. A photoradical polymerization initiator (component (I)) was added, and the mixture was heated and dissolved at 90 ° C. Cool to room temperature, thermal radical polymerization initiator (component (C)), silane coupling agent (component (F)), thermosetting agent (component (H)), organic filler (component (D)), inorganic filler ( Component (E)) and the like are added, stirred, dispersed with a three-roll mill, filtered with a metal mesh (635 mesh), and a sealant for a liquid crystal dropping method (Examples 1 to 4, Comparative Examples 1 to 2). Was prepared.

[Glass transition temperature]
The liquid crystal sealant produced in Examples and Comparative Examples was sandwiched between polyethylene terephthalate (PET) films to form a thin film with a thickness of 100 μm, and then a metal halide lamp (manufactured by Ushio Denki Co., Ltd.) was used at 3000 mJ / cm ² (100 mW / cm ²⁾ . After irradiating with ultraviolet rays (30 seconds), the film was placed in an oven at 120 ° C. for 40 minutes to cure. After curing, the PET film was peeled off to obtain a sealant cured film, which was cut into strips of 50 mm × 5 mm to prepare sample pieces. This sample piece was measured in the tensile mode of a dynamic viscoelasticity measuring device (DMS-6100: manufactured by SII Nanotechnology) under the conditions of a frequency of 10 Hz and a temperature rise temperature of 3 ° C./min, and the loss elastic modulus and storage. The loss coefficient Tan δ can be obtained from the ratio with the elastic modulus (JIS K 7244-1). The temperature at which the obtained loss coefficient Tan δ became the maximum value was defined as the glass transition temperature. The results are shown in Table 1.

[Evaluation of Examples 1 to 4 and Comparative Examples 1 and 2]
[Humidity permeability]
The liquid crystal sealant produced in Examples and Comparative Examples was sandwiched between polyethylene terephthalate (PET) films to form a thin film having a thickness of 100 μm, which was irradiated ^{with ultraviolet rays of 3000 mJ / cm 2 by} a UV irradiator and then put into an oven at 120 ° C. It was heat-cured for 40 minutes, and after curing, the PET film was peeled off to prepare a sample. The moisture permeability of the sample at 60 ° C. and 90% was measured with a moisture permeability measuring machine (manufactured by Lessy: L80-5000). The results are shown in Table 1.
[Evaluation of moisture permeability]
○: 200g ^{/ m} 2 · 24 hours less ×: 200g ^{/ m} 2 · 24 hours or more

[Flexibility]
A cured sealant film was prepared by the same method as the glass transition point measurement method, and cut into a rectangular shape having a length of 50 mm, a width of 5 mm, and a thickness of 0.1 mm to prepare a sample piece. The obtained sample was wound around a 2 mmΦ rod and fixed for 10 seconds. Those with unbroken test pieces were evaluated as ◯, and those with broken test pieces were evaluated as x. The results are shown in Table 1.
[Evaluation of flexibility]
◯: The test piece is not cracked ×: The test piece is cracked

[Shear adhesive strength]
1 g of 5 μm glass fiber is added as a spacer to 100 g of the liquid crystal sealant produced in Examples and Comparative Examples, and mixing and stirring are performed. A test piece was obtained by dropping a sealant on a 50 mm × 50 mm raw glass, placing a 2 mm × 2 mm glass chip on the glass chip, and irradiating with an ultraviolet ray ^{of 3000 mJ / cm 2 with a UV irradiator.}
The shear adhesive strength of the obtained test piece was measured with a bond tester (manufactured by Seishin Shoji Co., Ltd .: SS-30WD). The results are shown in Table 1.

From the results in Table 1, the sealant containing (A) a curable compound and (B) a liquid rubber and having two or more glass transition points of the cured product has low moisture permeability and high flexibility. It is also excellent in general properties such as adhesive strength.

Since the liquid crystal sealant of the present invention has low moisture permeability and high flexibility, it can be applied to flexible displays and curved displays.

Claims (11)

It contains (A) a curable compound , ( B) a liquid crystal , and (I) a photoradical polymerization initiator , and (A-1) (meth) acrylic compound and (A-2) are contained in the component (A). ) A liquid crystal sealant for a liquid crystal dripping method containing an epoxy compound, which has two or more glass transition points of a cured product of the liquid crystal sealant. The liquid crystal sealant for a liquid crystal dropping method according to claim 1, wherein one of the glass transition points is 10 ° C. or lower and one is 40 ° C. or higher. The liquid crystal sealant for the liquid crystal dropping method according to claim 1 or 2, further comprising (C) a thermal radical polymerization initiator. The liquid crystal sealant for the liquid crystal dropping method according to any one of claims 1 to 3 , further comprising (D) an organic filler. The liquid crystal for the liquid crystal dropping method according to claim 4 , wherein the component (D) is one or more organic fillers selected from the group consisting of urethane fine particles, acrylic fine particles, styrene fine particles, styrene olefin fine particles, and silicone fine particles. Sealant. The liquid crystal sealant for the liquid crystal dropping method according to any one of claims 1 to 5 , further comprising (E) an inorganic filler. The liquid crystal sealant for the crystal dropping method according to any one of claims 1 to 6 , further comprising (F) a silane coupling agent. The liquid crystal sealant for the liquid crystal dropping method according to any one of claims 1 to 7 , further comprising (H) a thermosetting agent. The liquid crystal sealant for a liquid crystal dropping method according to claim 8, wherein the component (H) is an organic acid hydrazide compound. In a liquid crystal display cell composed of two substrates, after dropping liquid crystal into the weir of the liquid crystal sealant for the liquid crystal dropping method according to any one of claims 1 to 9, which is formed on one of the substrates. A method for manufacturing a liquid crystal display cell, which comprises bonding the other substrate and then curing by heat. A liquid crystal display cell sealed with a cured product obtained by curing the liquid crystal sealant for the liquid crystal dropping method according to any one of claims 1 to 9.