JP7432492B2 - Liquid crystal sealant for liquid crystal dripping method - Google Patents

Description

The present invention relates to a liquid crystal sealant for liquid crystal dropping method, and a liquid crystal display cell sealed with the cured product.

In recent years, transparent displays have been developed, and attempts have been made to provide transparent materials such as automobile windshields, shop windows, and partitions with a display function (Patent Document 1). Among them, liquid crystal displays have fewer circuits per unit pixel than organic EL displays and other displays, so they have the characteristic of providing high transparency.

However, since liquid crystal sealants generally appear white because the solid filler they contain scatters light, there has been a problem in that the appearance of the liquid crystal display is impaired by the liquid crystal sealant.

In order to improve the transparency of liquid crystal sealants, it is necessary to reduce the amount of solid fillers that cause scattering, but with conventional liquid crystal sealants, reducing the amount of filler reduces the adhesive strength to the base material. However, there was a problem in that the liquid crystal sealant peeled off due to external stress or impact.

JP2020-016710A

An object of the present invention is to provide a liquid crystal sealant for liquid crystal dropping method that achieves both transparency and high adhesiveness, which have been considered difficult in the past, and a liquid crystal display cell sealed with the cured product thereof.

As a result of extensive studies, the present inventors have discovered that a specific liquid crystal sealant for liquid crystal dropping method achieves both transparency and high adhesiveness, leading to the present invention.
In addition, in this specification, "(meth)acrylate" means "acrylate" and/or "methacrylate."

That is, the present invention relates to the following [1] to [6].
[1]
A liquid crystal sealant for a liquid crystal dropping method containing a curable compound, a filler, and a thermosetting agent,
The primary particle diameter of the filler is 0.3 μm or less,
The content of the filler is 5 parts by mass or less with respect to 100 parts by mass of the curable compound,
A liquid crystal sealant for liquid crystal dropping method, which has a haze value of 60% or less when the cured product has a film thickness of 100 μm.
[2]
The liquid crystal sealant for the liquid crystal dropping method according to item [1] above, wherein the cured product has an elastic modulus of 2000 MPa or less at 25° C. as measured by a universal testing machine.
[3]
The liquid crystal sealant for liquid crystal dropping method according to the above item [1] or [2], which contains urethane (meth)acrylate as the curable compound.
[4]
The urethane (meth)acrylate is obtained by reacting (a) a polyol having an aromatic ring, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate as described in item [3] above. Liquid crystal sealant for liquid crystal dripping method.
[5]
The liquid crystal sealant according to any one of the above items [1] to [4], which is a sealant for transparent liquid crystal displays.
[6]
A liquid crystal display cell sealed with the liquid crystal sealant for the liquid crystal dropping method according to any one of the preceding clauses [1] to [4].

The present invention can provide a liquid crystal sealant for a liquid crystal dropping method that achieves both transparency and high adhesiveness, and a liquid crystal display cell sealed with the cured product thereof.

It is a drawing of a bonded substrate for adhesion testing.

The liquid crystal sealant for the liquid crystal dropping method of the present invention contains a curable compound, a filler, and a thermosetting agent, and the primary particle size of the filler is 0.3 μm or less, and the content of the filler is equal to or less than the curable compound. The amount is 5 parts by mass or less per 100 parts by mass, and the haze value of the cured product at a film thickness of 100 μm is 60% or less.

The particle size of the filler can be measured using a laser diffraction/scattering particle size distribution analyzer (dry type) (manufactured by Seishin Enterprise Co., Ltd.; LMS-30). Furthermore, if it is a commercially available product, the values specified in the catalogs of each company may be used instead of the above method.

Liquid crystal sealants appear white because the filler they contain scatters light. Therefore, in order to improve the transparency of the liquid crystal sealant, it is preferable to reduce the filler particle size and content. Specifically, the primary particle diameter of the filler is preferably 0.3 μm or less, more preferably 0.2 μm or less, and particularly preferably 0.1 μm or less. Although there is no particular preferable lower limit, it is preferably 0.01 μm or more in consideration of the kneadability with the liquid crystal sealant. Further, the content of the filler is preferably 5 parts by mass or less, more preferably 2.5 parts by mass or less, based on 100 parts by mass of the curable compound. Although there is no particular lower limit, it is preferably 1 part by mass or more in consideration of adhesiveness. The filler may be used alone or in combination.

The liquid crystal sealant of the present invention is preferably transparent. In the present invention, transparency was evaluated by the following transparency evaluation and haze evaluation.

For transparency evaluation, a liquid crystal cell is prepared, and the corners of the liquid crystal cell are observed using an optical microscope in transmission mode. At this time, it is preferable that the liquid crystal sealant is transparent and the boundary with the liquid crystal is only slightly visible, and it is more preferable that the liquid crystal sealant is almost integrated with the liquid crystal without being visible.

Haze evaluation was performed using a haze meter (Tokyo Denshoku: TC-H3DPK) of a 100 μm thick cured product that was irradiated with ultraviolet light at 3000 mJ/cm ² (measurement wavelength: 365 nm) and then cured for 60 minutes at 120°C. Measure the state with the zero point. The haze value is preferably 60% or less, more preferably 50% or less, and particularly preferably 40% or less.

The liquid crystal sealant of the present invention preferably has high adhesion. In the present invention, adhesiveness was evaluated as follows.

A liquid crystal sealant containing 1% by weight of 4 μm glass fiber was applied to the photo-alignment film substrate in a manner that reproduced the corner part of R = 0.5 mm and length of 1 cm x 1 cm, and the opposing photo-alignment film substrate was attached. After irradiating them with ultraviolet rays of 3000 mJ/cm ² (measurement wavelength: 365 nm) using a UV irradiator, they were heated at 120° C. for 60 minutes to bond. The obtained laminated substrate was cut into a shape with only the lower substrate protruding, assuming the terminal part of a display as shown in Figure 1, and a universal testing machine (manufactured by Shimadzu Corporation: Autograph AG-) equipped with a 3 mmφ needle-type terminal was used. Adhesive strength is determined by pressing the lower substrate at a point 4 mm diagonally away from the corner of the liquid crystal sealant applied with Xplus 500N and measuring the maximum load when the bonded substrate is peeled off. The adhesive strength is preferably 1.0 kgf or more, more preferably 1.5 kgf or more, particularly preferably 2.0 kgf or more, and most preferably 2.5 kgf or more.

The liquid crystal sealant of the present invention preferably has high flexibility. This is because a highly flexible liquid crystal sealant can be used for curved displays and highly flexible displays, and can follow the stress applied to the display. Flexibility can be evaluated by elastic modulus.
Room temperature when measuring a 100 μm thick cured product cured at 120°C for 60 minutes after irradiation with ultraviolet 3000 mJ/cm ² (measurement wavelength: 365 nm) using a universal testing machine (Shimadzu Corporation: Autograph AG-Xplus 500N) The elastic modulus at (25°C) is preferably 100 MPa or more and 3000 MPa or less, more preferably 300 MPa or more and 2000 MPa or less, particularly preferably 400 MPa or more and 1000 MPa or less.

[Curable compound]
The liquid crystal sealant of the present invention contains a curable compound. The curable compound is not particularly limited as long as it is a compound that can be cured by light, heat, etc., but it is preferably a compound having a (meth)acrylic group or an epoxy group, such as epoxy (meth)acrylate, urethane (meth)acrylate, etc. , polybutadiene compounds are particularly preferred.

[(Meta)acrylate]
Specific examples of (meth)acrylates include N-acryloyloxyethylhexahydrophthalimide, acryloylmorpholine, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexane-1,4-dimethanol mono( meth)acrylate, tetrahydrofurfuryl(meth)acrylate, phenoxyethyl(meth)acrylate, phenylpolyethoxy(meth)acrylate, 2-hydroxy-3-phenyloxypropyl(meth)acrylate, o-phenylphenol monoethoxy(meth)acrylate Acrylate, o-phenylphenol polyethoxy (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, tribromophenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, Cyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate ) acrylate, tricyclodecane dimethanol (meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A polypropoxy di(meth)acrylate, bisphenol F polyethoxy di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate (meth)acrylate, tris(acryloxyethyl)isocyanurate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tri- Pentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, neopentyl glycol and hydroxypivalic acid ester diacrylate and neo Monomers such as diacrylate of ε-caprolactone adduct of pentyl glycol and hydroxypivalic acid ester can be mentioned. Preferable examples include o-phenylphenol monoethoxy (meth)acrylate and o-phenylphenol polyethoxy (meth)acrylate.

[Epoxy (meth)acrylate]
Epoxy (meth)acrylate can be obtained by a known method by reacting an epoxy resin with (meth)acrylic acid. The raw material epoxy resin is not particularly limited, but bifunctional or higher functional epoxy resins are preferred, such as dimer acid-modified epoxy resin, resorcin diglycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin. , bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy Resins, glycidylamine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, phenol novolak type epoxy resins having a triphenolmethane skeleton, other diglycidyl etherified products of bifunctional phenols such as catechol and resorcinol, difunctional Examples include diglycidyl ethers of alcohols, and their halides and hydrogenated products. Among these, bisphenol A type epoxy resin and resorcin diglycidyl ether are preferred from the viewpoint of liquid crystal staining. 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.
Note that partial epoxy (meth)acrylate in which a part of the epoxy group is converted into acrylic ester is preferably used. In this case, the acrylation ratio is preferably about 30 to 70%.

[Urethane (meth)acrylate]
Because urethane (meth)acrylate has a flexible skeleton unique to the urethane structure, the cured product has the characteristics of flexibility and low moisture permeability, and can conform to bending in flexible displays, making it highly curable. It is preferable to use it as a compound, and it is more preferable to use one having a polyester structure.
Urethane (meth)acrylate can be synthesized by a conventional method by reacting (a) polyol, (b) organic polyisocyanate, and (c) hydroxyl group-containing (meth)acrylate, and tin may be added as necessary. Use a catalyst such as a compound.
In the synthesis of urethane (meth)acrylate, it is preferable to react 1.1 to 2.0 equivalents of isocyanate groups of component (b) with 1 equivalent of hydroxyl groups of component (a), and 1.3 to 2. It is particularly preferred to react .0 equivalents. The reaction temperature is preferably room temperature (25°C) to 100°C.
It is preferable to react 0.95 to 1.1 equivalents of hydroxyl groups in component (c) per equivalent of isocyanate groups in the reaction product of component (a) and component (b). The reaction temperature is preferably room temperature (25°C) to 100°C.

(a) Specific examples of polyols include tricyclodecanedimethanol, hydrogenated polybutadiene polyol, dimer diol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and 1,4-butanediol. , neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16 -Hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol, 1-methyl-1,8-octanediol, 2-methyl-1,8-octanediol, 3-methyl-1,5-pentane Diol, 2,4-diethyl-1,5-pentanediol, cyclohexane-1,4-dimethanol, polyethylene glycol, polypropylene glycol, bisphenol A poly(n≒2-20) ethoxydiol, bisphenol A poly(n≒2) ~20) Diols (a-1) such as propoxydiol, these diols (a-1) and dibasic acids or their anhydrides (e.g. succinic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, isophthalic acid, terephthalic acid) Examples include polyester polyol (a-2) which is a reaction product with acid, phthalic acid, or anhydride thereof. Preferred are polyester polyols and polyols having an aromatic ring, particularly preferred are polyester polyols having an aromatic ring. Examples of aromatic rings include aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, and phenanthroline ring; aromatic rings such as furan ring, pyrrole ring, thiophene ring, pyridine ring, thiazole ring, and benzothiazole ring. Heterocycle; preferably a benzene ring or a naphthalene ring.
Component (a) may be used alone or in combination of two or more.

(b) Specific examples of organic polyisocyanate include tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-cyclohexyl Methane diisocyanate, xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, trimethylhexamethylene diisocyanate, dimeryl diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate etc. can be mentioned. Preferred examples include tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate.

(c) Specific examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,4-butanediol (meth)acrylate, and polyethylene glycol mono(meth)acrylate. Acrylate, polypropylene glycol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, ε-caprolactone adduct of 2-hydroxyethyl(meth)acrylate, 2-hydroxy-3-phenyloxypropyl(meth)acrylate, etc. Can be done. Preferable examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

The lower limit of the weight average molecular weight of the urethane (meth)acrylate in terms of polystyrene in GPC is preferably 1,000 or more, more preferably 2,000 or more, particularly preferably 3,000 or more, and most preferably 4,000 or more. Further, the upper limit is preferably 10,000 or less, more preferably 8,000 or less, particularly preferably 7,000 or less, and most preferably 6,000 or less. By being within the above range, the viscosity of the liquid crystal sealing agent will be in an appropriate range while maintaining good flexibility and moisture permeability.

[Epoxy resin]
As an aspect of the present invention, it is also preferable that the curable compound contains an epoxy resin.
The epoxy resin is not particularly limited, but epoxy resins with two or more functionalities are preferred, such as dimer acid-modified epoxy resin, resorcin diglycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin. Epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, phenol novolac type epoxy resins having a triphenolmethane skeleton, diglycidyl etherified products of difunctional phenols such as catechol and resorcinol, and diglycidyl etherified products of difunctional alcohols such as catechol and resorcinol. Examples include glycidyl etherified products, halogenated products, and hydrogenated products thereof. Among these, bisphenol A type epoxy resin and resorcin diglycidyl ether are preferred from the viewpoint of liquid crystal staining.

[Polybutadiene compound]
It is also a preferred embodiment of the present invention to use a polybutadiene compound having an epoxy group or (meth)acrylic group in the curable compound. Polybutadiene compounds having epoxy groups are commercially available as JP-100 and JP-200 manufactured by Nippon Soda Co., Ltd., for example. Polybutadiene compounds having (meth)acrylic groups are commercially available as TEAI-1000 and TE-2000 manufactured by Nippon Soda Co., Ltd., for example.
The lower limit of the number average molecular weight of these polybutadiene compounds is preferably 500, more preferably 750, particularly preferably 1000, from the viewpoint of reducing liquid crystal contamination. Further, from the viewpoint of handling properties, the upper limit of the number average molecular weight is preferably 10,000, more preferably 8,000, particularly preferably 6,000.

As for the curable compound, the above-mentioned materials may be used alone, or two or more types may be mixed. In the liquid crystal sealant of the present invention, when a curable compound is used, it is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, based on the total amount of the liquid crystal sealant.

[Filler]
The liquid crystal sealant of the present invention contains a filler. From the viewpoint of transparency, the primary particle size of the filler is preferably 0.3 μm or less, more preferably 0.2 μm or less, and particularly preferably 0.1 μm or less. Although there is no particular lower limit, it is preferably 0.01 μm or more in consideration of miscibility with the liquid crystal sealant. The content of the filler is preferably 5 parts by mass or less, more preferably 2.5 parts by mass or less, based on 100 parts by mass of the curable compound. Although there is no particular lower limit, it is preferably 1 part by mass or more in consideration of adhesiveness. The filler may be used alone or in combination.

The filler contained in the liquid crystal sealant of the present invention may contain either an organic filler or an inorganic filler, or may contain both.
Examples of the organic filler include urethane particles, acrylic particles, styrene particles, styrene olefin particles, and silicone particles. Preferably, the silicone particles are KMP-594, KMP-597, KMP-598 (manufactured by Shin-Etsu Chemical Co., Ltd.), Trefil ^RTM E-5500, 9701, and EP-2001 (manufactured by Dow Corning Toray Industries, Inc.), and the urethane particles are preferably JB- 800t, HB -800BK (Negami Kogyo Co., Ltd.), styrene fine particles are Lavalon ^RTM T320C, T331C, SJ5400, SJ6400, SJ6400, SJ6300C, SJ5300C, SJ6300C (SJ6300C), preferably Stillen Chemicals. As an olefin fine particles, Cepton ^RTM SEPS2004, SEPS2063 is preferred.
These organic fillers may be used alone or in combination of two or more. Alternatively, two or more types may be used to form a core-shell structure. Among these, urethane fine particles, acrylic fine particles, styrene fine particles, and styrene olefin fine particles are preferred, and acrylic fine particles are particularly preferred.
When using the above-mentioned acrylic fine particles, it is preferable that the acrylic rubber has a core-shell structure consisting of two types of acrylic rubber, and it is particularly preferable that the core layer is n-butyl acrylate and the shell layer is methyl methacrylate. This is sold by Aica Kogyo Co., Ltd. as Zephiac ^RTM F-351S.
Examples of the silicone fine particles include crosslinked organopolysiloxane powder, linear dimethylpolysiloxane crosslinked powder, and the like. Moreover, as a composite silicone rubber, one in which the surface of the above-mentioned silicone rubber is coated with a silicone resin (for example, a polyorganosilsesquioxane resin) can be mentioned. Among these fine particles, particularly preferred are silicone rubber particles made of linear dimethylpolysiloxane crosslinked powder or composite silicone rubber particles made of silicone resin-coated linear dimethylpolysiloxane crosslinked powder. These organic fillers may be used alone or in combination of two or more.

Inorganic fillers include silica, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, Examples include calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, etc., and preferably fused silica, crystalline silica, silicon nitride, boron nitride, calcium carbonate, Examples include barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate, and aluminum silicate, with silica, alumina, and talc being preferred. Two or more of these inorganic fillers may be used in combination.

[Thermosetting agent]
The liquid crystal sealant of the present invention contains a thermosetting agent.
Examples of the thermosetting agent include compounds having a carboxy group bonded to an aromatic ring in the molecule, polyvalent amines, polyvalent phenols, organic acid hydrazides, and the like. However, it is not limited to these. For example, aromatic hydrazides such as terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 2,6-pyridine dihydrazide, 1,2,4-benzene trihydrazide, 1,4,5,8-naphthoic acid Tetrahydrazide, pyromellitic acid tetrahydrazide, etc. can be mentioned. In addition, if it is an aliphatic hydrazide, for example, form hydrazide, acetohydrazide, propionic acid hydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, sebacic acid dihydrazide, 1 , 4-cyclohexane dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, iminodiacetic acid dihydrazide, N,N'-hexamethylene bissemicarbazide, citric acid trihydrazide, nitriloacetic acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, 1,3-bis(hydrazide) Dihydrazide, tris(1-hydrazinocarbonylmethyl)isocyanurate having a hydantoin skeleton such as dinocarbonoethyl-5-isopropylhydantoin, preferably a valinehydantoin skeleton (a skeleton in which the carbon atoms of the hydantoin ring are substituted with isopropyl groups) , tris(2-hydrazinocarbonylethyl)isocyanurate, tris(1-hydrazinocarbonylethyl)isocyanurate, tris(3-hydrazinocarbonylpropyl)isocyanurate, bis(2-hydrazinocarbonylethyl)isocyanurate, etc. I can give it to you. In view of the balance between curing reactivity and latency, isophthalic acid dihydrazide, malonic acid dihydrazide, adipic acid dihydrazide, tris(1-hydrazinocarbonylmethyl)isocyanurate, tris(1-hydrazinocarbonylethyl)isocyanurate, tris( These include 2-hydrazinocarbonylethyl) isocyanurate and tris(3-hydrazinocarbonylpropyl)isocyanurate, and particularly preferred is tris(2-hydrazinocarbonylethyl)isocyanurate.

[Curing accelerator]
The liquid crystal sealant of the present invention can be further improved in reactivity by adding a curing accelerator. Examples of the curing accelerator include organic acids and imidazole.
Examples of the organic acid include organic carboxylic acids and organic phosphoric acids, but organic carboxylic acids are preferred. Specifically, aromatic carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, benzophenonetetracarboxylic acid, and furandicarboxylic 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, etc. .
In addition, as imidazole compounds, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecyl imidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 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, 2:3 of 2-methylimidazole isocyanuric acid Adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-3,5-dihydroxymethylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 1-cyanoethyl-2-phenyl-3,5- Dicyanoethoxymethylimidazole and the like can be mentioned.
In the liquid crystal sealant of the present invention, when a curing accelerator is used, it is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the total amount of the liquid crystal sealant.

[Radical photopolymerization initiator]
The liquid crystal sealant of the present invention may contain a photoradical polymerization initiator. The photoradical polymerization initiator is not particularly limited as long as it is a compound that generates radicals or acids and initiates a chain polymerization reaction when irradiated with ultraviolet rays or visible light, but examples include benzyl dimethyl ketal and 1-hydroxycyclohexyl phenyl ketone. , diethylthioxanthone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane, 2,4,6- Examples 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, OXE03, OXE04, DAROCURE ^RTM 1173, LUCIRIN ^RTM TPO (any Also made by BASF ), Sequal ^RTM Z, BZ, BEE, BIP, BBI (all manufactured by Seiko Kagaku Co., Ltd.), and the like. Among these, oxime ester initiators IRGACURE ^RTM OXE01, OXE02, OXE03, and OXE04 are preferred.
In addition, from the viewpoint of liquid crystal staining, it is preferable to use compounds having (meth)acrylic groups in the molecule, such as 2-methacryloyloxyethyl isocyanate and 1-[4-(2-hydroxyethoxy)-phenyl]- A reaction product with 2-hydroxy-2methyl-1-propan-1-one is preferably used. This compound can be obtained by manufacturing according to the method described in International Publication No. 2006/027982.
In the liquid crystal sealant of the present invention, when using a photoradical polymerization initiator, it is preferably 0.001 to 3% by mass, more preferably 0.002 to 2% by mass, based on the total amount of the liquid crystal sealant. be.

[Thermal radical polymerization initiator]
The liquid crystal sealant of the present invention can contain a thermal radical polymerization initiator to improve curing speed and curing properties.
The thermal radical polymerization initiator is not particularly limited as long as it is a compound that generates radicals when heated and initiates a chain polymerization reaction, but examples include organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol, etc. Benzopinacol is preferably used. For example, the organic peroxides include Kayamec ^RTM A, M, R, L, LH, SP-30C, Perkadox CH-50L, BC-FF, Kadox B-40ES, Perkadox 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 , Kayacarbon ^RTM BIC-75, AIC-75 (manufactured by Kayaku Akzo Co., Ltd.), Permec ^RTM N, H, S, F, D, G, Perhexa ^RTM H, HC, TMH, C, V, 22, MC, Percure ^RTM AH, AL, HB, Perbutyl ^RTM H, C, ND, L, Permil ^RTM H, D, Perloil ^RTM IB, IPP, Perocta ^RTM ND (manufactured by NOF Corporation), etc. are available as commercial products.

Further, as azo compounds, VA-044, 086, V-070, VPE-0201, VSP-1001 (manufactured by Wako Pure Chemical Industries, Ltd.), etc. are available as commercial products.

The content of the thermal radical polymerization initiator is preferably 0.0001 to 10% by mass, more preferably 0.0005 to 5% by mass, and 0.001% by mass, more preferably 0.0005 to 5% by mass, based on the total amount of the liquid crystal sealant of the present invention. ~3% by weight is particularly preferred.

The liquid crystal sealant of the present invention may further contain additives such as a silane coupling agent, a radical polymerization inhibitor, a pigment, a leveling agent, an antifoaming agent, and a solvent, if necessary.

[Silane coupling agent]
Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Trimethoxysilane, 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 , 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane and the like. These silane coupling agents are sold by Shin-Etsu Chemical Co., Ltd. as the KBM series, KBE series, etc., and are therefore easily available on the market. When a silane coupling agent is used in the liquid crystal sealant of the present invention, it is preferably used in an amount of 0.05 to 3% by mass based on the total amount of the liquid crystal sealant.

[Radical polymerization inhibitor]
The above-mentioned radical polymerization inhibitor is not particularly limited as long as it is a compound that prevents polymerization by reacting with radicals generated from photoradical polymerization initiators, thermal radical polymerization initiators, etc., and includes quinone-based, piperidine-based, Hindered phenol type, nitroso type, etc. can be used. Specifically, naphthoquinone, 2-hydroxynaphthoquinone, 2-methylnaphthoquinone, 2-methoxynaphthoquinone, 2,2,6,6-tetramethylpiperidine-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 hydroxyanisole, 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-methyl) phenyl)propionyloxy]ethyl], 2,4,8,10-tetraoxaspiro[5,5]undecane, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxy) phenylpropionate) methane], 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-sec-triazine-2,4,6-(1H,3H,5H ) trione, paramethoxyphenol, 4-methoxy-1-naphthol, thiodiphenylamine, aluminum salt of N-nitrosophenylhydroxyamine, trade name Adekastab LA-81, product name Adekastab LA-82 (manufactured by Adeka Co., Ltd.), etc. However, it is not limited to these. Among these, naphthoquinone-based, hydroquinone-based, nitroso-based, and piperazine-based radical polymerization inhibitors are preferred; naphthoquinone, 2-hydroxynaphthoquinone, hydroquinone, 2,6-di-tert-butyl-P-cresol, Polystop 7300P (Hakuto Co., Ltd.) 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 more preferably 0.01 to 0.2% by mass in the total amount of the liquid crystal sealant of the present invention. is particularly preferred.

An example of a method for obtaining the liquid crystal sealant of the present invention is the following method. First, a curable compound and, if necessary, a photoradical polymerization initiator, a thermal radical polymerization initiator, and a radical polymerization inhibitor are heated and dissolved. Next, after cooling to room temperature, a thermosetting agent, a curing accelerator, a filler, a silane coupling agent, an antifoaming agent, a leveling agent, a solvent, etc. are added as necessary, and the mixture is mixed using a known mixing device such as a three-roll or sand mill. The liquid crystal sealing agent of the present invention can be produced by uniformly mixing the ingredients using a ball mill or the like and filtering through a metal mesh.

Examples of the liquid crystal display cell of the present invention are shown below.

The liquid crystal display cell of the present invention has a pair of substrates each having a predetermined electrode formed thereon, which are arranged facing each other at a predetermined interval, the periphery of which is sealed with the liquid crystal sealant of the present invention, and liquid crystal is sealed in the gap between them. be. The type of liquid crystal to be sealed is not particularly limited. Here, the substrate is composed of a combination of glass, quartz, plastic, silicon, etc., at least one of which has optical transparency. The manufacturing method includes adding a spacer (gap control material) such as glass fiber to the liquid crystal sealant of the present invention, and then applying the liquid crystal sealant to one of the pair of substrates using a dispenser or screen printing device. After that, temporary curing is performed at 80 to 120°C, if necessary. Thereafter, liquid crystal is dropped inside the weir of the liquid crystal sealant, and the other glass substrate is placed on top of the other glass substrate in a vacuum to form 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 30 minutes to 2 hours. When used as a photothermal combination type, the liquid crystal sealant portion is irradiated with ultraviolet rays using an ultraviolet irradiator to photocure. The amount of ultraviolet irradiation is preferably 500 to 6000 mJ/cm ² , more preferably 1000 to 4000 mJ/cm ² (measurement wavelength: 365 nm). Thereafter, if necessary, the liquid crystal display cell of the present invention can be obtained by curing at 90 to 130°C for 30 minutes to 2 hours. The thus obtained liquid crystal display cell of the present invention has no display defects due to liquid crystal contamination and has excellent adhesiveness and moisture resistance reliability. Examples of the spacer include glass fiber, silica beads, and polymer beads. The diameter thereof varies depending on the purpose, but is preferably 2 to 8 μm, more preferably 4 to 7 μm. The amount used is preferably 0.1 to 4 parts by mass, more preferably 0.5 to 2 parts by mass, particularly preferably 0.9 to 1.5 parts by mass, per 100 parts by mass of the liquid crystal sealant of the present invention. It is about parts by mass.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the Examples. In addition, unless otherwise specified, "parts" and "%" in the text are based on mass.

[Synthesis example 1]
In a flask equipped with a thermometer, cooling tube, and stirring device, 776.99 g of a polyester polyol of methylpentanediol, adipic acid, and isophthalic acid (P-2012 manufactured by Kuraray Co., Ltd., hydroxyl value 54.6 mgKOH/g) and toluene were placed. 131.68 g of diisocyanate (Coronate T-100 manufactured by Tosoh Corporation, molecular weight 174.2) was charged and reacted at 80°C. The isocyanate content at this time was determined by adding excess amine and back titrating with hydrochloric acid, and it was confirmed that the value was within plus or minus 2% of the residual amount of isocyanate determined from the calculated value. Next, 0.6 g of methoquinone (polymerization inhibitor), 90.43 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.3 g of dibutyltin dilaurate (catalyst) were added, and the mixture was stirred at 80°C, and the infrared absorption spectrum was measured. The reaction was carried out until the absorption spectrum (2280 cm ^-1 ) of the isocyanate group disappeared, and a urethane acrylate oligomer having a weight average molecular weight of 6300 was obtained.

[Synthesis example 2]
100 parts (0.28 mol) of commercially available benzopinacol (manufactured by Tokyo Kasei) was dissolved in 350 parts of dimethyl formaldehyde. To this were added 32 parts (0.4 mol) of pyridine as a base catalyst and 150 parts (0.58 mol) of BSTFA (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silylating agent, and the mixture was heated to 70°C and stirred for 2 hours. The resulting reaction solution was cooled and, while stirring, 200 parts of water was added to precipitate the product and deactivate the unreacted silylating agent. The precipitated product was separated by filtration and thoroughly washed with water. The obtained product was then dissolved in acetone and recrystallized by adding water for purification. 105.6 parts (yield: 88.3%) of the desired 1,2-bis(trimethylsiloxy)-1,1,2,2-tetraphenylethane were obtained.

[Examples 1 to 17, Comparative Examples 1 to 9]
After heating and dissolving a curable compound, a photoradical polymerization initiator, and a radical polymerization inhibitor in the proportions shown in Tables 1 to 3 below at 90°C, the mixture is cooled to room temperature, and the thermal radical polymerization initiator, thermosetting agent, and curing accelerator are dissolved. After adding and stirring the agent, organic filler, inorganic filler, and silane coupling agent, the mixture was dispersed in a three-roll mill and filtered through a metal mesh (635 mesh) to prepare a liquid crystal sealant. The particle diameter of the filler used was the value specified in each company's catalog.

[evaluation]
[Haze]
The liquid crystal sealants produced in Examples and Comparative Examples were sandwiched between polyethylene terephthalate (PET) films to form a thin film with a thickness of 100 μm. After irradiating ultraviolet rays of 3000 mJ/cm ² (measured wavelength: 365 nm) with a UV irradiation machine, It was placed in an oven and heat-cured at 120°C for 60 minutes. After cutting the resulting cured film into a 3 cm x 3 cm square, the polyethylene terephthalate film was peeled off, and the haze value was measured using a haze meter (TC-H3DPK, manufactured by Tokyo Denshoku) with the empty state as the zero point. The results are listed in Tables 1-3.

[Elastic modulus]
The liquid crystal sealants produced in Examples and Comparative Examples were sandwiched between polyethylene terephthalate (PET) films to form a thin film with a thickness of 100 μm. After irradiating ultraviolet rays of 3000 mJ/cm ² (measured wavelength: 365 nm) with a UV irradiation machine, It was placed in an oven and heat-cured at 120°C for 60 minutes. The obtained cured film was cut out into dumbbell-shaped test pieces with an overall length of 75 mm, an overall width of 10 mm, and a thickness of 100 μm (narrow parallel portion length 30 mm x width 5 mm) in accordance with JIS7113-1 (1/2). After that, the polyethylene terephthalate film was peeled off, and tensile measurements were performed using a universal testing machine (Shimadzu Corporation: Autograph AG-Xplus 500N) at a temperature of 25°C, a grip length of 50 mm, and a test speed of 5 mm/min. The elastic modulus was calculated from the results of tensile stress and strain within. The results are listed in Tables 1-3.

[Preparation of substrate with alignment film using photo-alignment treatment]
A photo-alignment film liquid (NRB-U738, manufactured by Nissan Chemical Industries, Ltd.) was spin-coated on a glass substrate, calcined for 3 minutes on a hot plate at 80°C, and then baked in an oven at 230°C for 30 minutes. Then, alignment treatment was performed by irradiating ultraviolet rays of 500 mJ/cm ² (measurement wavelength: 254 nm) with a UV irradiation machine equipped with a polarization filter, and a photo-alignment film substrate was obtained by baking in an oven at 230°C for 30 minutes. Ta.

[Transparency evaluation]
1% by weight of 4 μm glass fiber was added as a spacer to the liquid crystal sealants prepared in Examples and Comparative Examples, and the mixture was mixed and stirred using a planetary stirrer (VMX-360, manufactured by EME). After applying the adjusted liquid crystal sealant in a square shape of 1 cm x 1 cm on the prepared photo-alignment film substrate, a predetermined amount of liquid crystal (MLC-3007, manufactured by Merck & Co., Ltd.) was dropped in the center, and the sealants were placed facing each other under vacuum. After bonding together the photo-alignment film substrates, a liquid crystal cell was produced by irradiating ultraviolet rays of 3000 mJ/cm ² (measurement wavelength: 365 nm) with a UV irradiation machine and heating at 120° C. for 60 minutes. The corners of the obtained liquid crystal cell were observed in the transmission mode of an optical microscope. ○ indicates that the liquid crystal sealant is transparent and almost integrated with the liquid crystal without visible boundaries, and △ indicates that the boundary is slightly visible. Those in which the transparency was impaired due to scattering of the filler in the liquid crystal sealant and the boundary with the liquid crystal was clearly visible were evaluated as ×. The results are listed in Tables 1-3.

[Adhesive strength]
1% by weight of 4 μm glass fiber was added as a spacer to the liquid crystal sealants prepared in Examples and Comparative Examples, and the mixture was mixed and stirred using a planetary stirrer (VMX-360, manufactured by EME). The prepared liquid crystal sealant was applied onto the prepared photo-alignment film substrate in a manner that reproduced the corner part of R = 0.5 mm and length 1 cm x 1 cm, the opposing photo-alignment film substrates were bonded together, and a UV irradiation machine was applied. After irradiating with ultraviolet rays of 3000 mJ/cm ² (measurement wavelength: 365 nm), the adhesive was bonded by heating at 120° C. for 60 minutes. The obtained laminated substrate was cut into a shape with only the lower substrate protruding, assuming the terminal part of a display as shown in Figure 1, and a universal testing machine (manufactured by Shimadzu Corporation: Autograph AG-) equipped with a 3 mmφ needle-type terminal was used. The adhesive strength was determined by pressing the lower substrate at a point 4 mm diagonally away from the corner of the liquid crystal sealant applied with Xplus 500N and measuring the maximum load when the bonded substrate peeled off. As a result, the adhesive strength is 2.0 kgf or more, which is sufficiently strong, ○, the adhesive strength is slightly inferior, 1.0 kgf or more and less than 2.0 kgf, △, and the adhesive strength is clearly insufficient when it is less than 1.0 kgf. The items that are true were rated as ×. The results are listed in Tables 1-3.

From the results in Tables 1 to 4, it was confirmed that the liquid crystal sealant of the present invention has both transparency and high adhesiveness. Furthermore, it was confirmed that the liquid crystal sealant of the present invention also has high flexibility.

The liquid crystal sealant of the present invention is particularly useful as a liquid crystal sealant for transparent liquid crystal displays, since it has both transparency and high adhesiveness.

Claims (6)

A liquid crystal sealant for a liquid crystal dropping method containing a curable compound, a filler, and a thermosetting agent,
The primary particle diameter of the filler is 0.3 μm or less,
The content of the filler is 5 parts by mass or less with respect to 100 parts by mass of the curable compound,
A liquid crystal sealant for a liquid crystal dropping method, in which the cured product is transparent and has a haze value of 60% or less at a film thickness of 100 μm. The liquid crystal sealant for liquid crystal dropping method according to claim 1, wherein the cured product has an elastic modulus of 2000 MPa or less at 25°C as measured by a universal testing machine. The liquid crystal sealant for liquid crystal dropping method according to claim 1 or 2, which contains urethane (meth)acrylate as the curable compound. The liquid crystal according to claim 3, wherein the urethane (meth)acrylate is obtained by reacting (a) a polyol having an aromatic ring, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate. Liquid crystal sealant for dripping method. The liquid crystal sealant for liquid crystal dropping method according to any one of claims 1 to 4, which is a sealant for transparent liquid crystal displays. A liquid crystal display cell sealed with the liquid crystal sealant for liquid crystal dropping method according to any one of claims 1 to 5.

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