JP7267899B2 - Liquid crystal sealant for liquid crystal dropping method and liquid crystal display cell using the same - Google Patents

Description

The present invention relates to a liquid crystal sealant for a liquid crystal dropping method and a liquid crystal display cell using the same.

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

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

In order to solve this problem, a liquid crystal sealant for the liquid crystal dripping method is currently used in combination with light and heat, and has been put to practical use (Patent Documents 3 and 4). The liquid crystal dripping method using the liquid crystal sealant is characterized in that the liquid crystal sealant sandwiched between the substrates is irradiated with light for primary curing, and then heated for secondary curing. 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 into the liquid crystal can be suppressed. In addition, with photocuring alone, the problem of insufficient adhesive strength due to curing shrinkage during photocuring occurs, but with photocuring combined with heat and heat, the stress relaxation effect can be obtained by secondary curing by heating, and such problems can be solved. have
With the commercialization of this photo-thermosetting type liquid crystal sealant for the liquid crystal dropping method, the liquid crystal dropping method has become a generally used method.

However, in recent years, various improvements have been made for the purpose of further increasing the definition, increasing the brightness, and narrowing the frame of the liquid crystal display. ing.
One of them is the improvement of the adhesive strength to the alignment film. This is because the liquid crystal sealant for the liquid crystal dripping method is arranged in the alignment film portion, and the line width (the width of the liquid crystal sealant) is narrowed, resulting in a small adhesion area.
In particular, the improvement of adhesion to the recently used photo-alignment film is becoming an important issue, and the current situation is that a sufficiently satisfactory liquid crystal sealant for the liquid crystal dropping method has not been proposed (Patent Document 5). ).

JP-A-63-179323 JP-A-10-239694 Japanese Patent No. 3583326 JP-A-2004-61925 JP 2016-024240 A

The present invention proposes a liquid crystal sealant for a liquid crystal dropping method, which has excellent adhesiveness to an alignment film, particularly a photo-alignment film.

Conventionally, a liquid crystal sealant has been required to have adhesiveness to a glass substrate with an ITO film. However, as the frame of the liquid crystal panel becomes narrower, the liquid crystal sealant is drawn on the alignment film, and the line width of the sealant becomes narrower. As a result of intensive studies, the present inventors have found that there is a certain relationship between the diiodomethane contact angle of the cured liquid crystal sealant and the alignment film adhesiveness, and completed the present invention.

That is, the present invention relates to the following [1] to [5]. In this specification, "liquid crystal sealant for liquid crystal dropping method" may be abbreviated simply as "liquid crystal sealant", but has the same meaning. Moreover, "(meth)acrylate" means "acrylate" and/or "methacrylate".
[1]
A liquid crystal sealing agent for liquid crystal dropping method containing (A) a curable compound and (B) a thermosetting agent, wherein the diiodomethane contact angle θ1 of the cured liquid crystal sealing agent for liquid crystal dropping method and the diiodomethane contact angle of the alignment film A liquid crystal sealant for a liquid crystal dropping method, wherein the absolute value of the difference in θ2 (θ1−θ2) is 15° or less.
[2]
A liquid crystal sealing agent for liquid crystal dropping method containing (A) a curable compound and (B) a thermosetting agent, wherein the cured product of the liquid crystal sealing agent for liquid crystal dropping method has a diiodomethane contact angle θ1 of 35° or less. Liquid crystal sealant for drip method.
[3]
The liquid crystal sealant for a liquid crystal dropping method according to the preceding item [1] or [2], which contains a partial epoxy (meth)acrylate as the component (A).
[4]
Furthermore, the liquid crystal sealing compound for liquid crystal dripping method according to any one of the preceding items [1] to [3], further comprising (C) a thermal radical polymerization initiator.
[5]
A liquid crystal display cell adhered using the liquid crystal sealant for liquid crystal dropping method according to any one of the preceding items [1] to [4].

INDUSTRIAL APPLICABILITY The present invention can provide a liquid crystal sealant for a liquid crystal dripping method that is excellent in adhesiveness to an alignment film.

1 shows the relationship between the alignment film adhesion strength of a liquid crystal sealant and the diiodomethane contact angle θ1 of a cured product of the liquid crystal sealant.

[(A) curable compound]
The liquid crystal sealant of the present invention contains a curable compound (hereinafter also simply referred to as "component (A)") as component (A).
Component (A) is not particularly limited as long as it is a compound that is cured by light, heat, or the like, but is preferably (meth)acrylate or epoxy resin, and epoxy (meth)acrylate or urethane (meth)acrylate. is particularly preferred.

[(Meth)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-phenylphenoxyethyl (meth)acrylate , o-phenylphenol polyethoxy (meth) acrylate, p-cumylphenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, tribromophenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclo Pentenyl (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, tripenta Erythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, neopentyl glycol and hydroxypivalic acid ester diacrylate and neopentyl Monomers such as diacrylates of ε-caprolactone adducts of esters of glycol and hydroxypivalic acid may be mentioned. N-acryloyloxyethylhexahydrophthalimide, phenoxyethyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate are preferred.

[Epoxy (meth)acrylate]
Epoxy (meth)acrylates are obtained by known methods by reacting epoxy resins with (meth)acrylic acid. The epoxy resin used as a raw material is not particularly limited, but is preferably a bifunctional or higher epoxy resin, such as resorcinol diglycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin. , phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolak 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, other diglycidyl ethers of bifunctional phenols such as catechol and resorcinol, diglycidyl ethers of bifunctional alcohols compounds, and halides and hydrogenated products thereof. Among these, bisphenol A type epoxy resin and resorcinol diglycidyl ether are preferable from the viewpoint of liquid crystal contamination. Moreover, the ratio of the epoxy group and the (meth)acryloyl group is not limited, and is appropriately selected from the viewpoint of process compatibility.
In addition, a partial epoxy (meth)acrylate in which a part of the epoxy group is acryl-esterified is preferably used. In this case, the acrylic ratio is preferably about 30 to 70%.
(Meth)acrylates may be used alone or in combination of two or more. In the liquid crystal sealing agent of the present invention, when (meth)acrylate is used, it is usually 10 to 80% by mass, preferably 20 to 70% by mass, based on the total amount of the liquid crystal sealing agent.

[Urethane (meth)acrylate]
Urethane (meth)acrylate has a flexible skeleton that is unique to the urethane structure, so the cured product has the characteristics of flexibility and low moisture permeability, and can follow the bending of flexible displays. A) is preferably used.
The urethane (meth)acrylate can be obtained by reacting (a) a polyol, (b) an organic polyisocyanate and (c) a hydroxyl group-containing (meth)acrylate and synthesizing it by a conventional method. A catalyst such as a chemical compound is used.
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). 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 reactants of components (a) and (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 Polyester diol (a-2) which is a reaction product with acid, phthalic acid, or their anhydrides, and the like can be mentioned. Preferred are tricyclodecanedimethanol, dimer diol, 1,9-nonanediol, 3-methyl-1,5-pentanediol and polyester diols thereof.
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. Tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate are preferred.

(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. Preferred are 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 1000 or more, more preferably 2000 or more, particularly preferably 3000 or more, and most preferably 4000 or more. Also, 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 in the above range, the viscosity of the liquid crystal sealant is in an appropriate range while maintaining good flexibility and moisture permeability.

[Epoxy resin]
As an embodiment of the present invention, it is more preferable that the component (A) further contains an epoxy resin.
Although the epoxy resin is not particularly limited, a bifunctional or higher epoxy resin is preferable. Epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolak type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type Epoxy resins, isocyanurate-type epoxy resins, phenolic novolac-type epoxy resins having a triphenolmethane skeleton, diglycidyl-etherified products of bifunctional phenols such as catechol and resorcinol, diglycidyl-etherified products of bifunctional alcohols, and these Halides and hydrogenated products of Among these, bisphenol A type epoxy resin and resorcinol diglycidyl ether are preferable from the viewpoint of liquid crystal contamination.

A preferable content of component (A) is 5 to 50% by mass, more preferably 10 to 30% by mass, based on the total amount of the liquid crystal sealant.

[(B) Thermosetting agent]
The liquid crystal sealant of the present invention contains a thermosetting agent (hereinafter also simply referred to as "component (B)") as component (B) to improve reactivity.
Examples of component (B) 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, 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 Tetrahydrazide, pyromellitic acid tetrahydrazide and the like can be mentioned. Examples of aliphatic hydrazides include formhydrazide, acetohydrazide, propionic hydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, sebacic acid dihydrazide, 1 ,4-cyclohexanedihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, iminodiacetic acid dihydrazide, N,N'-hexamethylenebissemicarbazide, citric acid trihydrazide, nitriloacetic acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, 1,3-bis(hydrazide dihydrazide and tris(1-hydrazinocarbonylmethyl)isocyanurate having a hydantoin skeleton such as dinocarbonoethyl)-5-isopropylhydantoin, preferably a valine hydantoin skeleton (a skeleton in which a carbon atom of the hydantoin ring is substituted with an isopropyl group) , tris (2-hydrazinocarbonylethyl) isocyanurate, tris (1-hydrazinocarbonylethyl) isocyanurate, tris (3-hydrazinocarbonylpropyl) isocyanurate, bis (2-hydrazinocarbonylethyl) isocyanurate, etc. I can give From 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( 2-hydrazinocarbonylethyl)isocyanurate, tris(3-hydrazinocarbonylpropyl)isocyanurate, particularly preferably tris(2-hydrazinocarbonylethyl)isocyanurate.
As component (B), it is preferable to use a compound having a carboxy group bonded to an aromatic ring in the molecule. -(Aminomethyl)benzoic acid, 2-mercaptonicotinic acid.
Component (B) may be used alone or in combination of two or more. In the liquid crystal sealing agent of the present invention, when component (B) is used, it is usually 0.1 to 10% by mass, preferably 0.1 to 5% by mass, based on the total amount of the liquid crystal sealing agent.

[Diiodomethane contact angle θ1 of cured liquid crystal sealant for liquid crystal dropping method]
The liquid crystal sealant of the present invention was sandwiched between polyethylene terephthalate (PET) films to form a thin film having a thickness of 100 μm, and was irradiated with a metal halide lamp (manufactured by Ushio Inc.) at 3000 mJ/cm ² (measurement wavelength: 365 nm, irradiation intensity: 100 mW/ cm ² ) of ultraviolet rays for curing, and then placed in an oven at 120° C. for 60 minutes for curing. Thereafter, the PET film was peeled off, and the sealant cured film was cut into a size of 5 cm×5 cm to obtain a sample piece. Diiodomethane is dropped on the obtained sample piece, and the contact angle θ1 is measured by the static drop method of JIS R3257 using an automatic dynamic contact angle meter (DCA-VZ manufactured by Kyowa Interface Science Co., Ltd.).

[Diiodomethane contact angle θ2 of alignment film]
An alignment liquid is applied to a glass substrate with an ITO film and cured under predetermined conditions. The alignment liquid may be either a rubbing alignment type or a photo-alignment type, but the photo-alignment type is preferred. For example, when using a photo-alignment type alignment liquid NRB-U738 manufactured by Nissan Chemical Industries, Ltd., the alignment liquid is spin-coated on a glass substrate, calcined on a 80 ° C. hot plate for 3 minutes, and then baked in a 230 ° C. oven for 30 minutes. Bake for a minute. Further, the substrate with the alignment film was irradiated with ultraviolet rays of 500 mJ/cm ² (measurement wavelength: 254 nm) using a UV irradiation machine, and baked in an oven at 230° C. for 30 minutes. Diiodomethane is dropped on the obtained glass substrate with the alignment film, and the contact angle θ2 is measured by the static drop method of JIS R3257 using an automatic dynamic contact angle meter (DCA-VZ manufactured by Kyowa Interface Science Co., Ltd.).

In the liquid crystal sealant of the present invention, the absolute value of the difference (θ1-θ2) between the diiodomethane contact angle θ1 of the cured product and the diiodomethane contact angle θ2 of the alignment film is preferably 15° or less. This is because when the contact angle difference between the two becomes smaller, the affinity increases and the bonding strength increases. 15° or less as an absolute value means that (θ1−θ2) is −15 or more and 15 or less. The lower limit of (θ1−θ2) is more preferably −10 or more, and particularly preferably 0 or more. The upper limit is preferably 10 or less.

Moreover, when the liquid-crystal sealing agent of this invention has a diiodomethane contact angle (theta) 1 of the hardened|cured material of 35 degrees or less, it is preferable. Since the contact angle of a general alignment film is often 20 to 25°, if θ1 is 35° or less, the affinity with the alignment film increases and the adhesive strength increases. θ1 is more preferably 32° or less, particularly preferably 28° or less. The lower limit of θ1 is preferably 10° or more, more preferably 15° or more, and particularly preferably 20° or more.

Moreover, in order to improve the adhesiveness about bending operation|movement of a flexible display, it becomes important to raise the softness|flexibility of a liquid crystal sealing agent hardened|cured material. In order to increase the flexibility of the cured product, it is effective to lower the crosslink density of the cured product. Therefore, it is important to achieve both flexibility and low moisture permeability of the cured product.
The elastic modulus of the liquid crystal sealant of the present invention is preferably 500 MPa or more and less than 3200 MPa, more preferably 1000 MPa or more and less than 2500 MPa. If the elastic modulus is less than 500 MPa, the bulk strength is low and the adhesive strength is low. On the other hand, when it exceeds 3200 MPa, it becomes difficult to follow the flexible display. The elongation at break is preferably 3% or more, more preferably 8% or more, particularly preferably 30% or more, and the preferred upper limit is less than 40%. This is because having a certain elongation at break makes it possible to withstand elongation of the liquid crystal sealant that accompanies bending of the substrate.
The moisture permeability of the liquid crystal sealing agent of the present invention is preferably 20 g/m ² · 24 hours or more and less than 100 g/m ² · 24 hours under the condition of 60 ° C. 90% RH, and 30 g / m ² · 24 hours or more. More preferably less than 90 g/m ² ·24 hours, more preferably 40 g/m ² ·24 hours or more and less than 60 g/m ² ·24 hours. This is to prevent water from entering in the humidity-resistant environment test.

[(C) Thermal radical polymerization initiator]
The liquid crystal sealant of the present invention can improve the curing speed and curability by containing (C) a thermal radical polymerization initiator (hereinafter also simply referred to as "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 organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol, etc. benzopinacol is preferably used. For example, 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.), Permek ^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, Permyl ^RTM H, D, Perroyl ^RTM IB, IPP, Perocta ^RTM ND (manufactured by NOF Corporation) and the like are commercially available.

As azo compounds, VA-044, 086, V-070, VPE-0201, VSP-1001 (manufactured by Wako Pure Chemical Industries, Ltd.) and the like are commercially available.

The content of component (C) is preferably 0.0001 to 10% by mass, more preferably 0.0005 to 5% by mass, based on the total amount of the liquid crystal sealing agent of the present invention. 3% by weight is particularly preferred.

[(D) organic filler]
The liquid crystal sealant of the present invention may contain an organic filler (hereinafter also simply referred to as "component (D)") as 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. KMP-594, KMP-597, KMP-598 (manufactured by Shin-Etsu Chemical Co., Ltd.), Torayfil ^RTM E-5500, 9701 and EP-2001 (manufactured by Dow Corning Toray Co., Ltd.) are preferred as the fine silicone particles, and JB- 800T, HB-800BK (Neagari Kogyo Co., Ltd.), Lavalon ^RTM T320C, T331C, SJ4400, SJ5400, SJ6400, SJ4300C, SJ5300C, and SJ6300C (manufactured by Mitsubishi Chemical) are preferable as styrene fine particles, and Septon ^RTM SEPS2004, as styrene olefin fine particles. SEPS2063 is preferred.
These organic fillers may be used alone or in combination of two or more. Moreover, it is good also as a core shell structure using 2 or more types. Among these, acrylic fine particles and silicone fine particles are preferred.
When the acrylic fine particles are used, it is preferable that the acrylic rubber has a core-shell structure composed of two kinds of acrylic rubbers, and particularly preferably, the core layer is n-butyl acrylate and the shell layer is methyl methacrylate. This is marketed by Aica Kogyo Co., Ltd. as Zephiac ^RTM F-351S.
Examples of the fine silicone particles include organopolysiloxane crosslinked powders and linear dimethylpolysiloxane crosslinked powders. Composite silicone rubbers include those obtained by coating the surface of the silicone rubber with a silicone resin (for example, polyorganosilsesquioxane resin). Among these fine particles, particularly preferred are silicone rubber particles of linear dimethylpolysiloxane crosslinked powder or composite silicone rubber particles of silicone resin-coated linear dimethylpolysiloxane crosslinked powder. These things may be used independently and may use 2 or more types together. Further, preferably, the shape of the rubber powder is spherical so that the increase in viscosity after addition is small. In the liquid crystal sealing agent of the present invention, when component (D) is used, it is usually 3 to 30% by mass, preferably 5 to 15% by mass, based on the total amount of the liquid crystal sealing agent.

[(E) Curing accelerator]
The liquid crystal sealant of the present invention can further improve the reactivity by adding a curing accelerator (hereinafter also simply referred to as "component (E)"). Examples of curing accelerators include amines and imidazoles, and imidazoles are particularly preferred. Examples of imidazoles include 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 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 adduct of 2-methylimidazole isocyanuric acid , 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-3,5-dihydroxymethylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 1-cyanoethyl-2-phenyl-3,5-dicyanoethoxy and methylimidazole.

[(F) photoradical polymerization initiator]
The liquid crystal sealant of the present invention may contain a photoradical polymerization initiator (hereinafter also simply referred to as "component (F)") as component (F). The photoradical polymerization initiator is not particularly limited as long as it is a compound that generates radicals or acids upon irradiation with ultraviolet light or visible light and initiates a chain polymerization reaction. 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- trimethylbenzoyldiphenylphosphine oxide, camphorquinone, 9-fluorenone, diphenyldisulfide and the like. Specifically, Omnirad 651, 184, 2959, 127, 907, 369, 379EG, TPO, 819, 754 (all manufactured by IGM Resins), Irgacure ^RTM OXE01, OXE02, OXE03, OXE04, (all manufactured by BASF ), Seikuol ^RTM Z, BZ, BEE, BIP, and BBI (all manufactured by Seiko Kagaku Co., Ltd.). Among these, Irgacure ^RTM OXE01, OXE02, OXE03 and OXE04, which are oxime ester initiators, are preferred.
Also, from the viewpoint of liquid crystal contamination, it is preferable to use those having a (meth)acrylic group in the molecule, such as 2-methacryloyloxyethyl isocyanate and 1-[4-(2-hydroxyethoxy)-phenyl]- Reaction products with 2-hydroxy-2methyl-1-propan-1-one are preferably used. This compound can be produced and obtained by the method described in International Publication No. 2006/027982.
In the liquid crystal sealing agent of the present invention, when component (F) is used, 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 sealing agent.

[(G) inorganic filler]
The liquid crystal sealant of the present invention can improve adhesive strength and moisture permeability by containing (G) an inorganic filler (hereinafter also simply referred to as "component (G)").
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, Calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, preferably fused silica, crystalline silica, silicon nitride, boron nitride, calcium carbonate, Barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate and aluminum silicate can be mentioned, with silica, alumina and talc being preferred. These inorganic fillers may be used in combination of two or more.
If the average particle size of the inorganic filler is too large, it may cause defects such as failure to properly form a gap when the upper and lower glass substrates are bonded together when manufacturing a liquid crystal display cell with a narrow gap. 300 nm or less, and more preferably 300 nm or less. A preferred lower limit is about 10 nm, more preferably about 100 nm. The particle size can be measured with a laser diffraction/scattering particle size distribution analyzer (dry type) (manufactured by Seishin Enterprise Co., Ltd.; LMS-30).
When component (G) is used in the liquid crystal sealing agent of the present invention, it is usually 5 to 50% by mass, preferably 10 to 30% by mass, based on the total amount of the liquid crystal sealing agent. If the content of component (G) is less than 5% by mass, the adhesion strength to the glass substrate is lowered, and the moisture resistance reliability is also inferior, so that the adhesion strength after moisture absorption may be greatly reduced. Moreover, when the content of component (G) is more than 50% by mass, the amount of component (G) is too large, so that it may become difficult to collapse, making it impossible to form a gap in the liquid crystal cell.

[(H) thiol compound]
The liquid crystal sealant of the present invention may contain a component (H) thiol compound (hereinafter also simply referred to as component (H)). The addition of component (H) is very useful because it reacts with the epoxy groups and reactive double bonds of component (A).
Component (H) is not particularly limited as long as it is a compound having a thiol group in the molecule, but from the viewpoint of storage stability and reactivity, a thiol compound having a secondary thiol group is preferred.
Moreover, the number of thiol groups in the molecule is preferably one having two or more (polyfunctional thiol compound), more preferably trifunctional or tetrafunctional.
The thiol equivalent of the thiol compound is preferably 80 or more, more preferably 100 or more, from the viewpoint of gas generation suppression. Also, the molecular weight is preferably 250 or more, more preferably 500 or more.
Component (H) may be used alone or in combination of two or more. In the liquid crystal sealing agent of the present invention, when component (H) is used, it is usually 0.5 to 20% by mass, preferably 1 to 10% by mass, based on the total amount of the liquid crystal sealing agent.

Additives such as a silane coupling agent, a radical polymerization inhibitor, a pigment, a leveling agent, an antifoaming agent, and a solvent can be added to the liquid crystal sealing agent of the present invention, 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 as KBM series, KBE series, etc. by Shin-Etsu Chemical Co., Ltd., etc., and are readily available on the market. When a silane coupling agent is used in the liquid crystal sealing agent 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 sealing agent.

[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 radical photopolymerization initiator, a thermal radical polymerization initiator, or the like to prevent polymerization. Hindered phenol type, nitroso type and the like 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 ) aluminum salt of trione, para-methoxyphenol, 4-methoxy-1-naphthol, thiodiphenylamine, N-nitrosophenylhydroxyamine, trade name Adekastab LA-81, tradename Adekastab LA-82 (manufactured by Adeka Co., Ltd.), and the like. but not limited to these. Of these, naphthoquinone-based, hydroquinone-based, nitroso-based, and piperazine-based radical polymerization inhibitors are preferred, and naphthoquinone, 2-hydroxynaphthoquinone, hydroquinone, 2,6-di-tert-butyl-p-cresol, Polystop 7300P (Hakuto Co., Ltd.) is more preferred, and Polystop 7300P (manufactured by Hakuto Co., Ltd.) is most preferred.
The content of the radical polymerization inhibitor is preferably 0.0001 to 1% by mass, more preferably 0.001 to 0.5% by mass, particularly preferably 0.01 to 0.2% by mass, based on the total amount of the liquid crystal sealing agent. .

As an example of the method for obtaining the liquid crystal sealing compound of the present invention, there is the method shown below. First, the component (F), a polymerization inhibitor and the like are heated and dissolved in the component (A), if necessary. Then, after cooling to room temperature, components (B), and optionally components (C), (D), (E), (G), and (H) silane coupling agents, antifoaming agents, leveling agents, solvents, etc. are added, mixed uniformly with a known mixing device such as a three-roll mill, a sand mill, a ball mill, etc., and filtered through a metal mesh to produce the liquid crystal sealant of the present invention.

A liquid crystal display cell manufactured using the liquid crystal sealing compound of the present invention is prepared by arranging a pair of substrates having predetermined electrodes formed on the substrates facing each other at a predetermined interval, sealing the periphery with the liquid crystal sealing compound of the present invention, and Liquid crystal is sealed in the gap. The type of liquid crystal to be enclosed is not particularly limited. Here, the substrate is composed of a combination of substrates, at least one of which is made of glass, quartz, plastic, silicon, or the like and has optical transparency. As a method for producing the liquid crystal sealing agent of the present invention, after adding a spacer (gap control material) such as glass fiber, the liquid crystal sealing agent is applied to one of the pair of substrates using a dispenser or a screen printer. After that, temporary curing is performed at 80 to 120° C., if necessary. After that, liquid crystal is dropped inside the weir of the liquid crystal sealant, and another glass substrate is overlapped 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 by an ultraviolet irradiator for photocuring. The UV irradiation dose is preferably 500 to 6000 mJ/cm ² , more preferably 1000 to 4000 mJ/cm ² (measured wavelength: 365 nm, irradiation intensity: 100 mW/cm ² ). After that, 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 is free from defective display due to liquid crystal contamination and is excellent in adhesiveness and humidity resistance reliability. Examples of spacers include glass fibers, silica beads, polymer beads, and the like. Although the diameter varies depending on the purpose, it is usually 2-8 μm, preferably 4-7 μm. The amount used is usually 0.1 to 4 parts by mass, preferably 0.5 to 2 parts by mass, and more preferably about 0.9 to 1.5 parts by mass based on 100 parts by mass of the liquid crystal sealing agent of the present invention. be.

Since the liquid crystal sealant of the present invention has excellent adhesiveness to alignment films, particularly photo-alignment films, it is also excellent in long-term reliability.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples. Unless otherwise specified, "parts" and "%" in the text are based on mass.

[Synthesis Example 1]
A thermometer, a condenser, a flask equipped with a stirrer, a polyester polyol of methylpentanediol and sebacic acid (P-2050 manufactured by Kuraray Co., Ltd., hydroxyl value 56.8mgK
OH/g), 98.2 g of tricyclodecanedimethanol (TCD alcohol DM manufactured by Celanese, molecular weight 196.3), and 444.6 g of isophorone diisocyanate (VESTANAT IPDI manufactured by Evonik, molecular weight 222.3) were 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 confirmed that the value was within the range of plus or minus 2% of the residual amount of isocyanate obtained from the calculated value.
Then, 0.9 g of methoquinone (polymerization inhibitor), 239.2 g of 2-hydroxyethyl acrylate (molecular weight: 116.1), and 0.5 g of dibutyltin dilaurate (catalyst) were added.
Stir at 0 ° C., infrared absorption spectrum of the isocyanate group (2280
cm-1) disappeared to obtain a urethane acrylate oligomer having a weight average molecular weight of 6,600.

[Synthesis Example 2]
100 parts (0.28 mol) of commercially available benzopinacol (manufactured by Tokyo Kasei) was dissolved in 350 parts of dimethylformaldehyde. 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 were added thereto, and the mixture was heated to 70° C. and stirred for 2 hours. The resulting reaction solution was cooled and 200 parts of water was added while stirring to precipitate the product and deactivate the unreacted silylating agent. After separating the precipitated product by filtration, it was thoroughly washed with water. The resulting product was then dissolved in acetone and recrystallized by adding water for purification. 105.6 parts of the desired 1,2-bis(trimethylsiloxy)-1,1,2,2-tetraphenylethane was obtained (yield 88.3%).

[Examples 1 to 6, Comparative Examples 1 to 3]
Components (A) and (F) were heated and mixed at 90° C. in the proportions shown in Table 2 below, then cooled to room temperature, and components (B), (C), (D), (E), and (G) were mixed. , and (O) were added, stirred, dispersed in a three-roll mill, and filtered through a metal mesh (635 mesh) to prepare a liquid crystal sealant.

[Contact angle θ1]
The liquid crystal sealing agents produced in Examples and Comparative Examples were sandwiched between polyethylene terephthalate (PET) films to form a thin film having a thickness of 100 μm, and a metal halide lamp (manufactured by Ushio Inc.) was irradiated with 3000 mJ/cm ² (measurement wavelength: 365 nm). , irradiation intensity: 100 mW/cm ² ), and then cured by placing in an oven at 120° C. for 60 minutes. Thereafter, the PET film was peeled off, and the sealant cured film was cut into a size of 5 cm×5 cm to obtain a sample piece. Diiodomethane was dropped on the obtained sample piece, and the contact angle θ1 was measured by the static drop method of JIS R3257 using an automatic dynamic contact angle meter (DCA-VZ manufactured by Kyowa Interface Science Co., Ltd.). Results are shown in Table 2.

[Contact angle θ2]
An alignment liquid (NRB-U738 manufactured by Nissan Chemical Industries, Ltd.) was spin-coated on a glass substrate with an ITO film, calcined on a hot plate at 80° C. for 3 minutes, and baked in an oven at 230° C. for 30 minutes. Further, the substrate with the alignment film was irradiated with ultraviolet rays of 500 mJ/cm ² (measurement wavelength: 254 nm) using a UV irradiation machine, and baked in an oven at 230° C. for 30 minutes. Diiodomethane was dropped on the obtained glass substrate with the alignment film, and the contact angle θ2 was measured by the static drop method of JIS R3257 using an automatic dynamic contact angle meter (DCA-VZ manufactured by Kyowa Interface Science Co., Ltd.). Results are shown in Table 1. Table 2 shows the values of (θ1-θ2).

[Elastic modulus, elongation at break]
The liquid crystal sealing agents produced in Examples and Comparative Examples were sandwiched between polyethylene terephthalate (PET) films to form a thin film having a thickness of 100 μm, and a metal halide lamp (manufactured by Ushio Inc.) was irradiated with 3000 mJ/cm ² (measurement wavelength: 365 nm). , irradiation intensity: 100 mW/cm ² ), and then cured by placing in an oven at 120° C. for 60 minutes. Thereafter, the PET film was peeled off, and the cured sealant film was cut into a dumbbell-shaped test piece (75 mm overall length, 10 mm overall width, 50 mm length of narrow parallel portion, 5 mm width) to obtain a sample piece. The resulting test piece was subjected to a tensile test using a Tensilon universal testing machine (RTG-1210, manufactured by A&D Co., Ltd.) at room temperature (22° C.) at a test speed of 5 mm/min, and the elastic modulus and Elongation at break was determined. Results are shown in Table 2.

[Moisture Permeability]
The liquid crystal sealing agents produced in Examples and Comparative Examples were sandwiched between polyethylene terephthalate (PET) films to form a thin film having a thickness of 300 μm, and a metal halide lamp (manufactured by Ushio Inc.) was irradiated with 3000 mJ/cm ² (measurement wavelength: 365 nm). , Irradiation intensity: 100 mW/cm ² ) and cured by irradiating it with ultraviolet rays, and then placed in an oven at 120° C. for 60 minutes for curing. After curing, the PET film was peeled off to obtain a sample. The moisture permeability of the sample at 60° C. 90% was measured with a moisture permeability meter (manufactured by Lyssy: L80-5000). Results are shown in Table 2.

[Adhesion strength]
An alignment film liquid (Nissan Chemical Industries, Ltd.: NRB-U738) was spin-coated on a glass substrate with an ITO film, calcined on a hot plate at 80° C. for 3 minutes, and baked in an oven at 230° C. for 30 minutes. Further, the substrate with the alignment film was irradiated with ultraviolet rays of 500 mJ/cm ² (measurement wavelength: 254 nm) using a UV irradiation machine, and baked in an oven at 230° C. for 30 minutes.
1 g of glass fiber of 5 μm as a spacer is added to 100 g of the sealant for displays produced in Examples and Comparative Examples, and mixed and stirred. On ^the glass substrate coated with the alignment film, this sealant for display was coated so as to reproduce a corner portion of 1 cm x 1 cm, and the opposing alignment film-coated substrates were bonded together. After being irradiated with ultraviolet rays having a wavelength of 365 nm, the film was placed in an oven and heat-cured at 120° C. for 60 minutes. The peeling adhesion strength of the orientation film-coated glass substrate was measured with a bond tester (manufactured by Seishin Shoji Co., Ltd.: SS-30WD) by pressing the corner portion. Results are shown in Table 2.

From the results in Table 2, it can be confirmed that the liquid crystal sealing compound of the present invention has excellent alignment film adhesiveness.

FIG. 1 shows the relationship between the adhesive strength of the alignment film of the liquid crystal sealant and the diiodomethane contact angle θ1 of the cured liquid crystal sealant. From FIG. 1, it is clear that the adhesive strength of the alignment film of the liquid crystal sealant is in a relationship that increases as the contact angle θ1 approaches θ2, especially when the absolute value of (θ1−θ2) is 15° or less. gives a more pronounced effect.

Since the liquid crystal sealing agent for the liquid crystal dropping method of the present invention is excellent in alignment film adhesiveness, it is useful as a flexible display or a curved liquid crystal sealing agent.

Claims (4)

(A) a curable compound, and (B) a liquid crystal sealing agent for a liquid crystal dropping method containing a thermosetting agent,
Contains a partial epoxy (meth)acrylate as the component (A),
The diiodomethane contact angle θ2 of the alignment film is 20 to 25°,
A liquid crystal sealing agent for liquid crystal dropping method, wherein the difference (θ1−θ2) between the diiodomethane contact angle θ1 of the cured product of the liquid crystal sealing agent for liquid crystal dropping method and the diiodomethane contact angle θ2 of the alignment film is 0° or more and 15° or less. The liquid crystal sealant for liquid crystal dropping method according to claim 1, wherein the contact angle θ1 is 20° or more and 35° or less. 3. The liquid crystal sealant for liquid crystal dropping method according to claim 1, further comprising (C) a thermal radical polymerization initiator. A liquid crystal display cell adhered using the liquid crystal sealing agent for liquid crystal dropping method according to any one of claims 1 to 3 .

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