Liquid crystal sealing agent, method for manufacturing a liquid crystal display panel, and liquid crystal display panel

Abstract

A liquid crystal sealing agent according to the present invention includes a curable compound (A), a thermosetting agent (B) and / or photopolymerization initiator (C), and alumina (D) having an α transformation rate of 80% or less.

Description

Technical Field

[0001] The present invention relates to a liquid crystal sealant, a method for manufacturing a liquid crystal display panel, and a liquid crystal display panel.

Background Art

[0002] A liquid crystal display panel generally has a pair of substrates, a frame-shaped seal member disposed between them, and a liquid crystal material enclosed in a region surrounded by the seal member. Such a liquid crystal display panel is manufactured by the liquid crystal droplet method.

[0003] In the liquid crystal droplet method, first, a rectangular seal pattern is formed on one of a pair of substrates by dispensing. Next, with the sealant in an uncured state, the liquid crystal material is dropped into the seal frame of the other substrate, the other substrate is superposed under vacuum, and the seal portion is irradiated with light such as ultraviolet rays for temporary curing. Then, it is heated for full curing to produce a liquid crystal display panel.

[0004] In recent years, with the narrowing of the bezel of liquid crystal display panels, a narrower line width of the seal member has also been demanded. Therefore, the seal member is required to have adhesiveness and moisture resistance with the substrate equal to or higher than those of the conventional one even when the width is narrowed, that is, to highly balance both adhesive strength and moisture resistance.

[0005] As a method for improving the moisture resistance of the sealant, a method of blending an inorganic filler such as talc or alumina has been studied. For example, in Patent Document 1, a sealant for a liquid crystal display element is proposed which contains a curable resin, a radical polymerization initiator and / or a thermosetting agent, and alumina, and the content of alumina exceeds 20 parts by mass with respect to 100 parts by mass of the curable resin (A). Further, in Patent Document 2, a sealant for a liquid crystal display element is proposed which contains a curable resin, a radical polymerization initiator or a thermosetting agent, and alumina or talc having an aspect ratio of 2 or more, and the content of alumina or talc is 85% by mass or more.

Prior Art Documents

Patent Documents

[0006] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2016-218447 Patent Document 2 Japanese Unexamined Patent Application Publication No. 2013-214056 Summary of the Invention Problems to be Solved by the Invention

[0007] As described above, by blending inorganic fillers such as talc and alumina, the moisture resistance of the seal member can be improved. However, since the flexibility of the seal member is impaired by the blending of the inorganic filler, there is a problem that the adhesive strength is likely to decrease. Thus, the adhesive strength and the moisture resistance are usually in a trade-off relationship, and it has been difficult to achieve both with conventional sealants.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide a liquid crystal sealant capable of forming a seal member having high moisture resistance and high adhesive strength with a substrate, a method for manufacturing a liquid crystal display panel using the same, and a liquid crystal display panel. Means for Solving the Problems

[0009] [1] A liquid crystal sealant containing a curable compound (A), a heat curing agent (B) and / or a photopolymerization initiator (C), and alumina (D) having a gelatinization rate of 80% or less. [2] The liquid crystal sealant according to [1], wherein the average particle diameter of the alumina (D) is 0.01 to 3 μm. [3] The liquid crystal sealant according to [1] or [2], wherein the content of the alumina (D) is 1 to 20 parts by mass with respect to 100 parts by mass of the curable compound (A). [4] The liquid crystal sealant according to any one of [1] to [3], wherein the aspect ratio of the alumina (D) is 2.0 or less. [5] The liquid crystal sealant according to any one of [1] to [4], wherein the alumina (D) is in a particulate form. [6] The liquid crystal sealant according to any one of [1] to [5], comprising a thermosetting compound (A1) having an epoxy group in the molecule and the thermosetting agent (B). [7] The liquid crystal sealant according to [6], wherein the content of the thermosetting compound (A1) is 5 to 20 parts by mass with respect to 100 parts by mass of the curable compound (A). [8] The liquid crystal sealant according to [6] or [7], wherein the content of the thermosetting agent (B) is 10 parts by mass or more with respect to 100 parts by mass of the curable compound (A). [9] The liquid crystal sealant according to any one of [6] to [8], wherein the thermosetting agent (B) contains at least one selected from the group consisting of dihydrazide-based thermally latent curing agents, imidazole-based thermally latent curing agents, amine adduct-based thermally latent curing agents, and polyamine-based thermally latent curing agents.

[10] The liquid crystal sealant according to any one of [6] to [9], further comprising a compound (A2) having an ethylenically unsaturated double bond in the molecule and the photopolymerization initiator (C), and the content ratio (A1 / A2) of the thermosetting compound (A1) and the compound (A2) is 30 / 70 to 50 / 50 (mass ratio).

[11] The liquid crystal sealant according to any one of [6] to

[10] , further comprising partial epoxy (meth)acrylate (A3) as the curable compound (A).

[12] The liquid crystal sealant according to any one of [1] to

[10] , wherein the photopolymerization initiator (C) contains at least one selected from the group consisting of oxime ester-based compounds, thioxanthone-based compounds, and anthraquinone-based compounds.

[13] The liquid crystal sealant according to any one of [1] to

[11] , further comprising a coupling agent.

[14] The liquid crystal sealant according to any one of [1] to

[13] , which is a liquid crystal sealant for the liquid crystal droplet method.

[15] A step of forming a seal pattern of the liquid crystal sealant according to any one of [1] to

[14] on one substrate; a step of dropping liquid crystal within the region of the seal pattern or on the other substrate paired with the one substrate while the seal pattern is in an uncured state; a step of overlapping the one substrate and the other substrate via the seal pattern; A method for manufacturing a liquid crystal display panel, comprising a step of curing the seal pattern.

[16] The method for manufacturing a liquid crystal display panel according to

[15] , wherein the step of curing the seal pattern includes a step of irradiating the seal pattern with light to cure the seal pattern.

[17] The method for manufacturing a liquid crystal display panel according to

[16] , wherein the light irradiated on the seal pattern includes light in the visible light region.

[18] The method for manufacturing a liquid crystal display panel according to

[16] or

[17] , wherein the step of curing the seal pattern further includes a step of heating and curing the seal pattern irradiated with light.

[19] A liquid crystal display panel including a pair of substrates, a frame-shaped seal member disposed between the pair of substrates, and a liquid crystal layer filled in a space surrounded by the seal member between the pair of substrates, wherein the seal member includes a cured product of the liquid crystal sealant according to any one of [1] to

[13] .

Effect of the Invention

[0010] According to the liquid crystal sealant of the present invention, a seal member having high moisture resistance and high adhesion strength to a substrate can be formed.

Mode for Carrying Out the Invention

[0011] In this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In the numerical ranges described step by step in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical ranges described in other step-by-step descriptions.

[0012] As mentioned above, alumina is sometimes added to liquid crystal sealants in order to impart moisture resistance and strength to the sealant. Alumina has various crystal phases, such as α, β, θ, and γ, depending on manufacturing conditions such as sintering temperature. Among them, alumina with the α crystal phase, which has the highest sintering temperature, is widely used because it has high heat resistance and is chemically stable. On the other hand, it has also been a factor in reducing the adhesive strength with the substrate.

[0013] In response to this, the present inventors have found that, among aluminas, alumina with an alpha conversion rate of a certain level or less not only improves the moisture resistance of the sealing member while preventing a decrease in adhesive strength with the substrate, but can actually improve the adhesive strength.

[0014] The reason for this is not clear, but is presumed to be as follows. Alumina (D) with a low alpha ratio has many hydroxyl groups easily coordinated around the aluminum atoms, and has many hydroxyl groups on the surface, compared with alumina with a high alpha ratio. This leads to the formation of hydrogen bonds between the hydroxyl groups of alumina (D) and the hydroxyl groups on the substrate, and between the hydroxyl groups of alumina (D) and the epoxy groups or hydroxyl groups (particularly epoxy groups) of the curable compound (A), which is believed to improve the adhesive strength to the substrate. The configuration of the liquid crystal sealant of the present invention will be specifically described below.

[0015] 1. Liquid crystal sealant The liquid crystal sealant of the present invention contains a curable compound (A), a heat curing agent (B) and / or a photopolymerization initiator (C) for curing the curable compound (A), and alumina (D) having an alpha-conversion rate of 80% or less, and may further contain other components such as an inorganic filler (E) as necessary. The curable compound may be any one of a monomer, an oligomer, and a polymer.

[0016] 1-1. Curing compound (A) 1-1-1. Thermosetting compound having an epoxy group in the molecule (A1) The above liquid crystal sealing agent may contain, as the curable compound (A), a thermosetting compound (A1) having an epoxy group in the molecule. It is preferable that the number of epoxy groups contained in the molecule of the thermosetting compound (A1) is 2 or more. In the present specification, the thermosetting compound (A1) does not include partial epoxy (meth)acrylate. Further, the thermosetting compound (A1) is preferably used together with a thermosetting agent (B) described later.

[0017] The thermosetting compound (A1) may be any of a monomer, an oligomer or a polymer. The thermosetting compound (A1) can further reduce the moisture permeability of the cured product and improve the display characteristics of the obtained liquid crystal display panel.

[0018] The weight average molecular weight of the thermosetting compound (A1) is preferably, for example, from 300 to 10,000, more preferably from 300 to 5,000. The weight average molecular weight of the thermosetting compound (A1) is measured in terms of polystyrene by gel permeation chromatography (GPC).

[0019] The thermosetting compound (A1) is preferably a compound having an aromatic ring. Examples of epoxy compounds having an aromatic ring include aromatic diols represented by bisphenol A, bisphenol S, bisphenol E, bisphenol F, bisphenol AD, etc., or diols obtained by modifying these aromatic diols with ethylene glycol, propylene glycol, alkylene glycol, etc., and aromatic polyvalent glycidyl ether compounds obtained by the reaction with epichlorohydrin, novolak resins derived from phenol or cresol and formaldehyde, polyphenols represented by polyalkenylphenol and its copolymers, etc., and novolak-type polyvalent glycidyl ether compounds obtained by the reaction with epichlorohydrin, and glycidyl ether compounds of xylylene phenol resin, etc. Among them, cresol novolak type epoxy compounds, phenol novolak type epoxy compounds, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, triphenol methane type epoxy compounds, triphenol ethane type epoxy compounds, tris-phenol type epoxy compounds, dicyclopentadiene type epoxy compounds, diphenyl ether type epoxy compounds or biphenyl type epoxy compounds are preferable. The liquid crystal sealing agent may contain only one kind of epoxy compound or may contain two or more kinds. Among them, bisphenol A type epoxy compounds having a bisphenol A skeleton in the molecule are preferable. The thermosetting compound (A1) may be liquid or solid.

[0020] The content of the thermosetting compound (A1) is preferably 2 to 40 parts by mass with respect to 100 parts by mass of the curable compound (A). When the content of the thermosetting compound (A1) is 2 parts by mass or more, it is easier to further increase the adhesion strength to the substrate. The thermosetting compound (A1) having an epoxy group has an epoxy group and a hydroxyl group (especially an epoxy group), and easily forms a hydrogen bond with the hydroxyl group on the surface of alumina (D), making it easy to increase the adhesion strength of the cured product. When the content of the thermosetting compound (A1) is 40 parts by mass or less, it is possible to more hardly impair the flexibility of the cured product. From the same viewpoint, the content of the thermosetting compound (A1) is more preferably 5 to 20 parts by mass, and even more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the curable compound (A).

[0021] 1-1-2. Compound (A2) having an ethylenically unsaturated double bond in the molecule The above liquid crystal sealant may contain, as the curable compound (A), a compound (A2) having an ethylenically unsaturated double bond in the molecule. In the present specification, the compound (A2) having an ethylenically unsaturated double bond in the molecule does not include partial epoxy (meth)acrylate. Further, the compound having an ethylenically unsaturated double bond in the molecule is preferably used together with a photopolymerization initiator (C) described later.

[0022] The compound (A2) having an ethylenically unsaturated double bond in the molecule may be any of a monomer, an oligomer or a polymer. Examples of the compound having an ethylenically unsaturated double bond in the molecule include compounds having a (meth)acryloyl group in the molecule. The number of (meth)acryloyl groups per molecule of the compound having the (meth)acryloyl group may be 1 or 2 or more.

[0023] In the present specification, "(meth)acrylate" means acrylate or methacrylate, "(meth)acryloyl group" means acryloyl group or methacryloyl group, "(meth)acrylic acid" means acrylic acid or methacrylic acid, and "(meth)acrylic acid resin" means acrylic resin or methacrylic resin.

[0024] Examples of the curable compound containing one (meth)acryloyl group in one molecule include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate.

[0025] Examples of the curable compound having two or more (meth)acryloyl groups in one molecule include di(meth)acrylate derived from polyethylene glycol, propylene glycol, polypropylene glycol, etc., di(meth)acrylate derived from tris(2-hydroxyethyl)isocyanurate, di(meth)acrylate derived from a diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol, di(meth)acrylate derived from a diol obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A or bisphenol F (bisphenol A or F type epoxy (meth)acrylate), di- or tri-(meth)acrylate derived from a polyol obtained by adding 2 moles or 3 moles of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane, di(meth)acrylate derived from a diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of bisphenol A, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, trimethylolpropane tri(meth)acrylate or its oligomer, pentaerythritol tri(meth)acrylate or its oligomer, poly(meth)acrylate of dipentaerythritol, tris(acryloxyethyl)isocyanurate, caprolactone-modified tris(acryloxyethyl)isocyanurate, caprolactone-modified tris(methacryloxyethyl)isocyanurate, poly(meth)acrylate of alkyl-modified dipentaerythritol, poly(meth)acrylate of caprolactone-modified dipentaerythritol, hydroxypivalic acid neopentyl glycol di(meth)acrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol di(meth)acrylate, ethylene oxide-modified phosphoric acid (meth)acrylate, ethylene oxide-modified alkylated phosphoric acid (meth)acrylate, and oligo(meth)acrylate of neopentyl glycol, trimethylolpropane and pentaerythritol, etc. are included.Among them, di(meth)acrylate (bisphenol A or F type epoxy (meth)acrylate) derived from a diol obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A or bisphenol F is preferred.

[0026] The weight average molecular weight of the compound (A2) having an ethylenically unsaturated double bond in the molecule, measured by gel permeation chromatography (GPC), is, for example, 200 to 10,000, preferably 200 to 5,000.

[0027] The content of the compound (A2) having an ethylenically unsaturated double bond in the molecule is preferably 10 to 50 parts by mass, more preferably 15 to 40 parts by mass, and even more preferably 20 to 35 parts by mass with respect to 100 parts by mass of the curable compound (A). When the content of the above compound (A2) is 20 parts by mass or more, the compound (A2) is more likely to be sufficiently cured during temporary curing by photocuring, so that liquid crystal contamination is more likely to be suppressed. When the content of the above compound (A2) is 30 parts by mass or less, the adhesive strength to the substrate is less likely to be impaired.

[0028] 1-1-3. Partial epoxy (meth)acrylate (A3) The above liquid crystal sealant may contain partial epoxy (meth)acrylate (A3) as the curable compound (A). The partial epoxy (meth)acrylate (A3) can enhance the adhesiveness of the cured product of the liquid crystal sealant to the substrate and can also enhance the compatibility between the thermosetting compound (A1) having an epoxy group and the compound (A2) having an ethylenically unsaturated double bond in the molecule.

[0029] The partial epoxy (meth)acrylate (A3) is a partial (meth)acryloyl-modified epoxy resin in which at least one epoxy group among the epoxy groups of a bifunctional or higher-functional epoxy resin is modified with a (meth)acryloyl group. The partial epoxy (meth)acrylate (A) can be obtained, for example, by reacting a bifunctional or higher-functional epoxy resin with (meth)acrylic acid in the presence of a basic catalyst.

[0030] The epoxy resin used as a raw material for the partial epoxy (meth)acrylate (A3) may be any epoxy resin having two or more epoxy groups in the molecule. Examples of the above epoxy resins include bisphenol type epoxy resins such as bisphenol A type, bisphenol F type, 2,2'-diallylbisphenol A type, bisphenol AD type, and hydrogenated bisphenol type; novolak type epoxy resins such as phenol novolak type, cresol novolak type, biphenyl novolak type, and tris-phenol novolak type; biphenyl type epoxy resins; and naphthalene type epoxy resins. Among these, bisphenol type epoxy resins such as bisphenol A type and bisphenol F type are preferred because of their low crystallinity and high coating stability.

[0031] In addition, the epoxy resin may be an epoxy resin having three or more epoxy groups, or four or more epoxy groups. However, from the viewpoint of appropriately adjusting the crosslinking density and increasing the adhesion strength of the cured product to the substrate, a bifunctional epoxy resin is preferred.

[0032] For the partial epoxy (meth)acrylate (A3), the ratio of the number of moles of (meth)acryloyl groups to the number of moles of epoxy groups is preferably 1 or more, and more preferably 2 or more. By increasing the ratio of the number of moles of (meth)acryloyl groups, it is easier to suppress the contamination of the liquid crystal due to the elution of the sealant into the liquid crystal.

[0033] The weight average molecular weight of the partial epoxy (meth)acrylate (A3) measured by gel permeation chromatography (GPC) is preferably 300 to 500.

[0034] The content of the partial epoxy (meth)acrylate (A3) is preferably 20 to 80 parts by mass, more preferably 30 to 70 parts by mass, and even more preferably 45 to 65 parts by mass with respect to 100 parts by mass of the curable compound (A). When the content of the partial epoxy (meth)acrylate (A3) is 20 parts by mass or more, it is easier to enhance the adhesion strength of the cured product while enhancing the compatibility of the thermosetting compound (A1) and the above compound (A2). When the content of the partial epoxy (meth)acrylate (A3) is 80 parts by mass or less, the flexibility of the cured product is less likely to be impaired.

[0035] 1-1-4. Common Matters The curable compound (A) preferably contains at least one of the thermosetting compound (A1), the compound (A2) having an ethylenically unsaturated double bond in the molecule, and the partial epoxy (meth)acrylate (A3), and more preferably contains all of them from the viewpoint of the balance between photocuring and thermosetting.

[0036] Also, the content ratio (A1 / A2) of the thermosetting compound (A1) and the compound (A2) having an ethylenically unsaturated double bond in the molecule can be set according to the required performance. For example, from the viewpoint of enhancing the adhesion strength to the substrate, it is preferable that the ratio of the thermosetting compound (A1) is large, and A1 / A2 is preferably 30 / 70 to 50 / 50 (mass ratio), and more preferably 40 / 60 to 50 / 50 (mass ratio).

[0037] 1-2. Thermosetting Agent (B) The above sealant contains a thermosetting agent (B) for curing the thermosetting compound (A1).

[0038] The thermosetting agent (B) is preferably a latent thermosetting agent. A latent thermosetting agent is a compound that does not cure the thermosetting compound (A1) or the partial epoxy (meth)acrylate (A3) under normal storage conditions (room temperature, visible light, etc.), but cures these compounds when heat is applied. The thermosetting agent (B) is preferably a curing agent capable of curing an epoxy compound (hereinafter also referred to as an "epoxy curing agent").

[0039] From the viewpoint of enhancing the viscosity stability of the photo-thermosetting resin composition and not impairing the moisture resistance of the cured product, the epoxy curing agent preferably has a melting point of 50 to 250°C, more preferably 100 to 200°C, and even more preferably 150 to 200°C.

[0040] Examples of the epoxy curing agent include dihydrazide-based thermally latent curing agents, imidazole-based thermally latent curing agents, dicyandiamide-based thermally latent curing agents, amine adduct-based thermally latent curing agents, and polyamine-based thermally latent curing agents. Among these, dihydrazide-based thermally latent curing agents, imidazole-based thermally latent curing agents, amine adduct-based thermally latent curing agents, and polyamine-based thermally latent curing agents are preferred. From the viewpoint of further enhancing the display characteristics, imidazole-based thermally latent curing agents, amine adduct-based thermally latent curing agents, and polyamine-based thermally latent curing agents are more preferred, and amine adduct-based thermally latent curing agents and polyamine-based thermally latent curing agents are even more preferred.

[0041] Examples of the dihydrazide-based thermally latent curing agent include adipic acid dihydrazide (melting point 181°C), 1,3-bis(hydrazinocarboethyl)-5-isopropylhydantoin (melting point 120°C), 7,11-octadecadiene-1,18-dicarbohydrazide (melting point 160°C), dodecanedioic acid dihydrazide (melting point 190°C), and sebacic acid dihydrazide (melting point 189°C).

[0042] Examples of the imidazole-based thermally latent curing agent include 2,4-diamino-6-[2’-ethylimidazolyl-(1’)]-ethyltriazine (melting point 215 to 225°C), and 2-phenylimidazole (melting point 137 to 147°C).

[0043] Examples of the dicyandiamide-based thermally latent curing agent include dicyandiamide (melting point 209°C).

[0044] The amine adduct-based latent heat curing agent is a latent heat curing agent composed of an addition compound obtained by reacting an amine-based compound having catalytic activity with an arbitrary compound. Examples of the amine adduct-based latent heat curing agent include Amicure PN-40 (melting point 110°C) manufactured by Ajinomoto Fine-Techno Co., Inc., Amicure PN-50 (melting point 120°C) manufactured by Ajinomoto Fine-Techno Co., Inc., Amicure PN-23 (melting point 100°C) manufactured by Ajinomoto Fine-Techno Co., Inc., Amicure PN-31 (melting point 115°C) manufactured by Ajinomoto Fine-Techno Co., Inc., Amicure PN-H (melting point 115°C) manufactured by Ajinomoto Fine-Techno Co., Inc., Amicure MY-24 (melting point 120°C) manufactured by Ajinomoto Fine-Techno Co., Inc., and Amicure MY-H (melting point 131°C) manufactured by Ajinomoto Fine-Techno Co., Inc. etc.

[0045] The polyamine-based latent heat curing agent is a latent heat curing agent having a polymer structure obtained by reacting an amine with an epoxy, and examples thereof include Adeka Hardener EH4339S (softening point 120 - 130°C) manufactured by ADEKA Corporation, and Adeka Hardener EH4357S (softening point 73 - 83°C) manufactured by ADEKA Corporation etc.

[0046] The content of the heat curing agent (B) is preferably 10 parts by mass or more, more preferably 15 - 30 parts by mass, with respect to 100 parts by mass of the curable compound (A). When the content of the heat curing agent (B) is 10 parts by mass or more, it is easy to enhance the curability of the thermosetting compound (A1). When the content of the heat curing agent (B) is 30 parts by mass or less, it is easier to suppress the contamination of the liquid crystal due to the elution of the heat curing agent (B) into the liquid crystal.

[0047] Also, the content of the heat curing agent (B) is preferably 50 - 300 parts by mass, more preferably 100 - 200 parts by mass, with respect to 100 parts by mass of the thermosetting compound (A1).

[0048] 1 - 3. Photoinitiator (C) The above liquid crystal sealant may contain a photoinitiator (C) for initiating the curing (polymerization) of the compound (A2) having an ethylenically unsaturated double bond in the molecule.

[0049] The photoinitiator (C) is not particularly limited as long as it is a compound capable of initiating the curing (polymerization) of the above compound. For example, the photoinitiator (C) can be a radical polymerization initiator, and may be a self-cleaving type photoinitiator or a hydrogen abstraction inorganic type photoinitiator.

[0050] Examples of self-cleaving photoinitiators include alkylphenone compounds, acylphosphine oxide compounds, titanocene compounds, acetophenone compounds, phenylglyoxylate compounds, benzoin ether compounds, and oxime ester compounds, etc. Examples of the above alkylphenone compounds include benzyldimethylketal such as 2,2-dimethoxy-1,2-diphenylethane-1-one (IRGACURE 651 manufactured by BASF), α-aminoalkylphenones such as 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one (IRGACURE 907 manufactured by BASF), and α-hydroxyalkylphenones such as 1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE 184 manufactured by BASF), etc. Examples of the above acylphosphine oxide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, etc. Examples of the above titanocene compounds include bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, etc. Examples of the above acetophenone compounds include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, etc. Examples of the above phenylglyoxylate compounds include methylphenylglyoxylate, etc. Examples of the above benzoin ether compounds include benzoin, benzoin methyl ether, and benzoin isopropyl ether, etc.Examples of the above oxime ester compounds include 1,2-octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] (IRGACURE OXE01 manufactured by BASF), and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(0-acetoxime) (IRGACURE OXE02 manufactured by BASF), etc.

[0051] Examples of hydrogen abstraction type photoinitiators include benzophenone compounds, thioxanthone compounds, anthraquinone compounds, and benzyl compounds. Examples of the above benzophenone compounds include benzophenone, methyl o-benzoylbenzoate-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone. Examples of the above thioxanthone compounds include thioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, 1-chloro-4-ethoxythioxanthone (Speedcure CPTX manufactured by Lambson Limited), 2-isopropylxanthone (Speedcure ITX manufactured by Lambson Limited), 4-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone (Speedcure DETX manufactured by Lambson Limited), 2,4-dichlorothioxanthone, and (2-carboxymethoxythioxanthone)-(polytetramethylene glycol 250) diester (Omnipol TX manufactured by IGM). Examples of the above anthraquinone compounds include 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 1-chloroanthraquinone, 2-hydroxyanthraquinone (2-Hydroxyanthraquinone manufactured by Tokyo Chemical Industry Co., Ltd.), 2,6-dihydroxyanthraquinone (Anthraflavic Acid manufactured by Tokyo Chemical Industry Co., Ltd.), and 2-hydroxymethylanthraquinone (2-(Hydroxymethyl)anthraquinone manufactured by Junsei Chemical Co., Ltd.).

[0052] The absorption wavelength of the photoinitiator (C) is not particularly limited, and for example, it can be a photoinitiator that absorbs light with a wavelength of 360 nm or more. Among them, it is more preferable to absorb light in the visible light region, a photoinitiator that absorbs light with a wavelength of 360 to 780 nm is even more preferable, and a photoinitiator that absorbs light with a wavelength of 360 to 430 nm is particularly preferable.

[0053] Examples of the photoinitiator that absorbs light with a wavelength of 360 nm or more include alkylphenone-based compounds, acylphosphine oxide-based compounds, titanocene-based compounds, oxime ester-based compounds, thioxanthone-based compounds, and anthraquinone-based compounds. Among these, oxime ester-based compounds, thioxanthone-based compounds, and anthraquinone-based compounds are preferable, and oxime ester-based compounds are more preferable.

[0054] The molecular weight of the photoinitiator (C) can be, for example, 200 to 5000. When the molecular weight of the photoinitiator (C) is 200 or more, the photoinitiator (C) is less likely to elute into the liquid crystal. On the other hand, when the molecular weight of the photoinitiator (C) is 5000 or less, the compatibility with various curable compounds (A) increases, and the curability of the sealant tends to be good. The molecular weight of the photoinitiator (C) is more preferably 230 to 3000, and even more preferably 230 to 1500.

[0055] The molecular weight of the photoinitiator (C) can be determined as the "relative molecular mass" of the molecular structure of the main peak detected when analyzed by high performance liquid chromatography (HPLC).

[0056] Specifically, a sample solution in which the photopolymerization initiator (C) is dissolved in THF (tetrahydrofuran) is prepared, and high-performance liquid chromatography (HPLC) measurement is performed. Then, the area percentage of the detected peaks (the ratio of the area of each peak to the total area of all peaks) is determined, and the presence or absence of the main peak is confirmed. The main peak refers to the peak with the highest intensity (the peak with the highest peak height) among all the peaks detected at the detection wavelength characteristic of each compound (for example, 400 nm for thioxanthone-based compounds). The relative molecular mass corresponding to the peak apex of the detected main peak can be measured by liquid chromatography-mass spectrometry (LC / MS).

[0057] The content of the photopolymerization initiator (C) is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the photocurable compound (for example, the total of the compound (A2) having an ethylenically unsaturated double bond in the molecule and the partial epoxy (meth)acrylate (A3)). When the above content is 0.01 part by mass or more, the photocurability of the sealant is easily enhanced, and when it is 10 parts by mass or less, it is easier to suppress the contamination of the liquid crystal due to the elution of the photopolymerization initiator (C) into the liquid crystal.

[0058] 1-4. Alumina (D) The liquid crystal sealant contains alumina (D) with an α-conversion rate of 80% or less. As described above, alumina (D) with a low α-conversion rate has many hydroxyl groups on its surface. Therefore, hydrogen bonds are likely to be formed particularly between the hydroxyl groups of alumina (D) and the epoxy groups of the thermosetting compound (A1), or between the hydroxyl groups of alumina (D) and the hydroxyl groups on the substrate, and it is considered that the adhesive strength to the substrate is improved.

[0059] The α-phase conversion rate of alumina (D) is 80% or less, preferably 50% or less, and more preferably 20% or less. When the α-phase conversion rate of alumina (D) is 50% or less, it is easier to further increase the adhesion strength to the substrate. The lower limit of the α-phase conversion rate is not particularly limited, but for example, from the viewpoint of facilitating the formation of uniform spheres, it is 1%, preferably 4%. The α-phase conversion rate of alumina (D) can be adjusted by production conditions such as the sintering temperature.

[0060] The α-phase conversion rate of alumina (D) can be measured by the following procedure. X-ray diffraction measurement was performed on powders obtained by mixing α-phase alumina powder AA-05 (manufactured by Sumitomo Chemical Co., Ltd.) and θ-phase alumina powder Timicron TM-100D (manufactured by Daimyo Chemical Co., Ltd.) at mass ratios of 0:10, 5:5, and 10:0. The integrated intensity of the α-phase peak detected at 2θ = 43° was calculated, and a calibration curve of the mixing ratio and the integrated intensity was created. Next, X-ray diffraction measurement was performed on the powder of alumina (D), the integrated intensity of the peak at 2θ = 43° was calculated, and the content of the α-phase, that is, the α-phase conversion rate (%), was determined by comparing with the above calibration curve. For X-ray diffraction, a JDX-3500 type X-ray diffractometer (manufactured by JEOL Ltd.) can be used.

[0061] The shape of alumina (D) is not particularly limited as long as the α-phase conversion rate satisfies the above range, and it may be any of spherical, crushed (plate-like), needle-like, etc. Among them, spherical alumina is preferable from the viewpoint of having a large surface area and being easy to improve the adhesion strength to the substrate.

[0062] The aspect ratio of alumina (D) is not particularly limited, but for example, it is preferably 2.0 or less, and more preferably 1.0 to 1.5. Alumina (D) with an aspect ratio of 2.0 or less has a large surface area and is easy to increase the adhesion strength to the substrate. Also, when used in a liquid crystal display panel, peeling due to the generation of stress concentration points is less likely to occur, and a further decrease in the adhesion strength can be suppressed.

[0063] The aspect ratio of alumina (D) is measured from an image taken with a scanning electron microscope (SEM). Twenty arbitrary particles are selected, the major axis and minor axis of each particle are measured, and the average major axis and average minor axis are calculated. Then, the average major axis and average minor axis can be calculated by applying them to the following formula. Aspect ratio = average major axis (μm) / average minor axis (μm)

[0064] The average particle size of alumina (D) is not particularly limited as long as it is within a range that matches the cell gap of the liquid crystal display panel. The average particle size of alumina (D) may be, for example, 0.01 to 25 μm, preferably 0.01 to 3 μm, and more preferably 0.1 to 2 μm. When the average particle size of alumina (D) is 0.01 μm or more, it is easier to further improve the moisture resistance of the cured product of the liquid crystal sealing agent. When the average particle size of alumina (D) is 3 μm or less, it is easier to further suppress the curing failure of the compound (A2) having an ethylenically unsaturated double bond in the molecule or the partial epoxy (meth) acrylate (A3) due to alumina (D) blocking or reflecting light during photocuring, and it is possible to further suppress liquid crystal contamination. The average particle size of alumina (D) can be measured by Microtrac MT3300.

[0065] The content of alumina (D) is preferably 2 to 25 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 7 to 15 parts by mass with respect to 100 parts by mass of the curable compound (A). The higher the content of alumina (D), the easier it is to further reduce the moisture permeability of the cured product. On the other hand, by not excessively increasing the content of alumina (D), the flexibility of the cured product is less likely to be impaired, and the adhesive strength is also less likely to be impaired. In addition, since the photocuring failure caused by light reflection by alumina (D) can be further suppressed, the liquid crystal contamination can be further reduced.

[0066] 1-5. Inorganic filler (E) The above liquid crystal sealing agent may further contain other inorganic fillers (E) other than alumina. The inorganic filler (E) can impart a predetermined hardness and linear expansibility to the cured product, suppress the permeation of moisture and the like through the inside of the cured product, and further reduce the moisture permeability of the cured product.

[0067] Examples of the inorganic filler (E) include calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, titanium nitride, alumina other than the above, zinc oxide, silicon dioxide (silica), potassium titanate, kaolin, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, and silicon nitride. Among these, silicon dioxide and talc are preferred.

[0068] The shape of the inorganic filler (E) may be a regular shape such as spherical, plate-like, needle-like, etc., or an irregular shape. When the inorganic filler (E) is spherical, the average primary particle diameter of the inorganic filler (E) is preferably 1.5 μm or less. Also, the specific surface area of the inorganic filler (E) is preferably 0.5 m 2 / g or more and 20 m 2 / g or less. The average primary particle diameter of the inorganic filler (E) can be measured by the laser diffraction method described in JIS Z8825 (2013). The specific surface area of the filler can be measured by the BET method described in JIS Z8830 (2013).

[0069] The content of the inorganic filler (E) is preferably 2 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the curable compound (A). The higher the content of the inorganic filler (E), the easier it is to further reduce the moisture permeability of the cured product and the higher the hardness of the cured product can be increased. On the other hand, by not increasing the content of the inorganic filler (E) too much, the flexibility of the cured product is less likely to be impaired and the adhesive strength is also less likely to be impaired.

[0070] 1-6. Others In addition to the above-described components, the liquid crystal sealant may contain a thermal radical generator, organic fine particles, a coupling agent such as a silane coupling agent, an ion trap agent, an ion exchanger, a leveling agent, a pigment, a dye, a sensitizer, a plasticizer, and an antifoaming agent.

[0071] Examples of the thermal radical polymerization initiator include organic peroxides, azo compounds, benzoins, benzoin ethers, and acetophenones.

[0072] The organic fine particles can reduce the residual stress during the application of the liquid crystal sealant. For example, the organic fine particles can be organic fine particles having an elastic core part containing a conjugated diene rubber and a silicone rubber, etc., and a shell part made of a polymer such as a (meth)acrylate, a vinyl monomer, and an epoxy monomer that enhance the compatibility with other components.

[0073] Alternatively, coated particles having a core particle (core) made of inorganic particles and a polymer layer covering the core and having a functional group containing a carbon-carbon double bond on the surface can also be used. The functional group containing a carbon-carbon double bond can be a vinyl group, an allyl group, an acrylic group, or a methacrylic group. Examples of the core particles include the same ones as those listed as the above inorganic filler (E), and silicas are preferable from the viewpoint of excellent thermal stability.

[0074] The content of the organic fine particles is preferably 5 to 17 parts by mass with respect to 100 parts by mass of the liquid crystal sealant. When the content of the organic fine particles is 5 parts by mass or more, the adhesive strength between the cured product and the substrate can be further enhanced. On the other hand, when the content of the organic fine particles is 17 parts by mass or less, the amount of other components (for example, curable compounds) becomes sufficiently large, and the strength of the cured product can be further enhanced.

[0075] Examples of the silane coupling agent include vinyltrimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane.

[0076] The content of the silane coupling agent is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the liquid crystal sealant. When the content of the silane coupling agent is 0.01 part by mass or more, the adhesive strength between the cured product and the substrate can be further enhanced.

[0077] The liquid crystal sealing agent may further contain a spacer or the like for adjusting the gap of the liquid crystal display panel.

[0078] The total amount of other components is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the liquid crystal sealing agent. When the total amount is 50 parts by mass or less, the viscosity of the sealing agent is less likely to increase excessively, and the coating stability of the sealing agent is less likely to be impaired.

[0079] 1-7. Physical properties of the sealing agent The viscosity of the liquid crystal sealing agent at 25 °C and 2.5 rpm of an E-type viscometer is preferably 200 to 450 Pa·s, and more preferably 300 to 400 Pa·s. When the viscosity is within the above range, the coatability of the sealing agent by a dispenser becomes good.

[0080] 2. Liquid crystal display panel and its manufacturing method The liquid crystal display panel of the present invention includes a pair of substrates (a display substrate and a counter substrate), a frame-shaped sealing member disposed between the pair of substrates, and a liquid crystal layer filled in a space surrounded by the sealing member between the pair of substrates.

[0081] Both the display substrate and the counter substrate are transparent substrates. The material of the transparent substrate may be an inorganic material such as glass, or may be a plastic such as polycarbonate, polyethylene terephthalate, polyethersulfone, and PMMA.

[0082] On the surface of the display substrate or the counter substrate, a matrix-shaped TFT, a color filter, a black matrix, etc. may be disposed. On the surface of the display substrate or the counter substrate, an alignment film is further disposed. The alignment film contains a known organic aligning agent or inorganic aligning agent.

[0083] The sealing member can be disposed between the display substrate or the counter substrate, preferably between the alignment films of the pair of substrates. The sealing member is a cured product of the liquid crystal sealing agent.

[0084] The liquid crystal display panel is manufactured using the liquid crystal sealant of the present invention. In the manufacturing method of a liquid crystal display panel, generally, there are a liquid crystal droplet method and a liquid crystal injection method. However, the liquid crystal display panel of the present invention is preferably manufactured by the liquid crystal droplet method.

[0085] The manufacturing method of a liquid crystal display panel by the liquid crystal droplet method is as follows. 1) A step of forming a seal pattern of the above liquid crystal sealant on one of a pair of substrates. 2) A step of dropping liquid crystal within a region surrounded by the seal pattern on one substrate or on the other substrate in a state where the seal pattern is uncured. 3) A step of overlapping one substrate and the other substrate via the seal pattern. 4) A step of curing the seal pattern.

[0086] In the step of 1), the above liquid crystal sealant may be applied on one substrate to form a seal pattern. The seal pattern may be disposed on the alignment film of one substrate or on the outer peripheral side of the alignment film, but is preferably disposed on the alignment film.

[0087] In the step of 2), the state where the seal pattern is uncured means a state where the curing reaction of the liquid crystal sealant has not progressed to the gel point. Therefore, in the step of 2), in order to suppress the dissolution of the liquid crystal sealant into the liquid crystal, the seal pattern may be semi-cured by light irradiation or heating. One substrate and the other substrate are a display substrate and a counter substrate, respectively.

[0088] In the step of 4), curing by light irradiation and subsequent curing by heating may be performed. By performing curing by light irradiation, the liquid crystal sealant can be cured in a short time, so that dissolution into the liquid crystal can be suppressed. By combining curing by light irradiation and curing by heating, damage to the liquid crystal layer by light can be reduced as compared with the case of only curing by light irradiation.

[0089] The light to be irradiated is appropriately selected according to the type of the photoinitiator (C) in the above-mentioned sealant, but light in the visible light region is preferable, and for example, light having a wavelength of 370 nm or more and 450 nm or less is preferable. This is because the light of the above wavelength causes relatively little damage to the liquid crystal material and the drive electrodes. For light irradiation, a known light source that emits ultraviolet rays or visible light can be used. When irradiating visible light, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a xenon lamp, a fluorescent lamp, or the like can be used.

[0090] The light irradiation energy may be energy capable of curing the above compound (A2) or the partial epoxy (meth) acrylate (A3). The photocuring time depends on the composition of the liquid crystal sealant, but is, for example, about 10 minutes.

[0091] The thermosetting temperature depends on the composition of the liquid crystal sealant, but is, for example, 120°C, and the thermosetting time is about 2 hours.

Examples

[0092] Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by these examples in any way, and modifications of the embodiments are possible without departing from the spirit of the present invention.

[0093] 1. Preparation of materials 1-1. Curable compound (A) 1-1-1. Thermosetting compound (A1) having an epoxy group in the molecule · Bisphenol A type epoxy resin (manufactured by ADEKA Corporation, EP-4000S, epoxy equivalent 260 g / eq)

[0094] 1-1-2. Compound (A2) having an ethylenically unsaturated double bond in the molecule · Bisphenol A type acrylic resin (manufactured by Daicel Ornex Co., Ltd., EBECRYL3700, weight average molecular weight 485)

[0095] 1-1-3. Partial epoxy (meth) acrylate (A3) · Acrylic-epoxy hybrid resin (manufactured by Neo Chemical Co., Ltd., BFEA-50, epoxy equivalent 470 g / eq)

[0096] 1-2. Thermosetting agent (B) · Amine adduct-based thermally latent curing agent (manufactured by Ajinomoto Fine-Techno Co., Inc., Amicure PN-50 ("Amicure" is a registered trademark of Ajinomoto Co., Inc.))

[0097] 1-3. Photoinitiator (C) · IRGACURE OXE-02 (manufactured by BASF Japan Ltd., oxime ester type)

[0098] 1-4. Alumina (D) · Alumina particles (D-1): manufactured by Denka Co., Ltd., ASFP-20 (α conversion rate: 10%, average particle diameter 0.3 μm, aspect ratio 1.1) · Alumina particles (D-2): manufactured by Denka Co., Ltd., ASFP-40 (α conversion rate: 10%, average particle diameter 0.4 μm, aspect ratio 1.1) · Alumina particles (D-3): ASFP-03S (α conversion rate: over 99%, average particle diameter 0.4 μm, aspect ratio 1.1) · Alumina particles (D-4): manufactured by Denka Co., Ltd., DAW-01 (α conversion rate: 5%, average particle diameter 1.9 μm, aspect ratio 1.1) · Alumina particles (D-5): manufactured by Denka Co., Ltd., DAW-03 (α conversion rate: 30%, average particle diameter 4.9 μm, aspect ratio 1.1) · Alumina particles (D-6): manufactured by Denka Co., Ltd., DAW-10 (α conversion rate: 50 - 80%, average particle diameter 12.0 μm, aspect ratio 1.1) · Alumina particles (D-7): manufactured by Denka Co., Ltd., DAW-20 (α conversion rate: 50 - 80%, average particle diameter 24.0 μm, aspect ratio 1.1)

[0099] The α conversion rate and average particle diameter of the alumina particles were measured by the following methods respectively.

[0100] (Measurement of α conversion rate) X-ray diffraction measurements were performed on powders obtained by mixing α-phase alumina powder AA-05 (manufactured by Sumitomo Chemical Co., Ltd.) and θ-phase alumina powder Timicron TM-100D (manufactured by Daimyo Chemical Co., Ltd.) at mass ratios of 0:10, 5:5, and 10:0. The integrated intensity of the α-phase peak detected at 2θ = 43° was calculated, and a calibration curve of the mixing ratio and the integrated intensity was created. Next, X-ray diffraction measurements were performed on the powder of alumina (D), the integrated intensity of the peak at 2θ = 43° was calculated, and the content rate of the α-phase, that is, the α-conversion rate (%), was determined by comparing with the above calibration curve. For the X-ray diffraction, a JDX-3500 type X-ray diffractometer (manufactured by JEOL Ltd.) was used.

[0101] (Measurement of average particle diameter) The average particle diameter of alumina (D) was measured by Microtrac MT3300.

[0102] (Measurement of aspect ratio) Regarding the aspect ratio of alumina (D), from the images measured by a scanning electron microscope (SEM), 20 arbitrary particles were selected, the major axis and the minor axis were measured respectively, and the average major axis and the average minor axis were calculated. Then, the average major axis and the average minor axis were applied to the following formula to calculate the aspect ratio. Aspect ratio = average major axis (μm) / average minor axis (μm)

[0103] 1-5. Others 1-5-1. Inorganic filler (E) · Silica particles: manufactured by Admatechs Co., Ltd., SO-C1

[0104] 1-5-2. Organic fine particles · Fine particle polymer F351 (manufactured by Aika Kogyo Co., Ltd.)

[0105] 1-5-3. Silane coupling agent · Silane coupling agent (KBM-403, manufactured by Shin-Etsu Silicone Co., Ltd.)

[0106] 2. Preparation of liquid crystal sealant (Example 1) 100 parts by mass of a thermosetting compound (A1), 140 parts by mass of a compound (A2) having an ethylenically unsaturated double bond in the molecule, 400 parts by mass of a partial epoxy (meth) acrylate (A3), 100 parts by mass of a thermosetting agent (B), 10 parts by mass of a photopolymerization initiator (C), 50 parts by mass of alumina particles (D-1), 130 parts by mass of an inorganic filler (E), 60 parts by mass of organic fine particles (F), and 10 parts by mass of a silane coupling agent (G) were thoroughly mixed using a three-roll mill to obtain a homogeneous liquid, thereby obtaining a liquid crystal sealant.

[0107] (Examples 2 to 10, Comparative Examples 1 to 2) A liquid crystal sealant was obtained in the same manner as in Example 1, except that the composition was changed as shown in Table 1.

[0108] 3. Evaluation For the liquid crystal sealants obtained in Examples 1 to 10 and Comparative Examples 1 to 2, the adhesive strength, moisture permeability, and liquid crystal contamination were evaluated by the following methods.

[0109] <Adhesive Strength> Using a dispenser (Shot Master, manufactured by Musashi Engineering), the obtained liquid crystal sealant was applied onto a 40 mm × 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC) on which a transparent electrode and an alignment film were previously formed to form a 38 mm × 38 mm square seal pattern (cross-sectional area 2500 μm 2 ). Next, a paired glass substrate was bonded under reduced pressure so as to be perpendicular to the glass substrate on which the seal pattern was formed, and then the pressure was released to the atmosphere for bonding. Then, the two bonded glass substrates were held in a light-shielding box for 1 minute, and then irradiated with light (light having a wavelength of 370 to 450 nm) including visible light of 3000 mJ / cm 2 and further heated at 120°C for 1 hour to cure the seal, thereby obtaining a test piece. A portion 4.5 mm from the corner of the seal pattern of the obtained test piece was vertically pushed in at a speed of 5 mm / min using a push-in tester (Model 210, manufactured by Intesco). This operation was performed on 10 glass substrates (n = 10), and the number of glass substrates that cracked was counted. Then, the adhesive strength was evaluated according to the following criteria. ◎: The number of cracked glass substrates is 7 - 10 pieces ○: The number of cracked glass substrates is 1 - 6 pieces ×: The number of cracked glass substrates is 0 pieces It can be judged that the higher the number of cracked glass substrates, the higher the adhesive strength. If it is ○ or more, it is at a level with no practical problems and is judged to be good.

[0110] <Moisture permeability> The obtained liquid crystal sealant was applied on release paper with an applicator to a thickness of 300 μm. Then, the applied sealant was put into a nitrogen replacement container, and after performing nitrogen purge for 5 minutes, it was irradiated with light of 3000 mJ / cm 2 (light calibrated with a wavelength 365 nm sensor), and further heated at 120 °C for 1 hour to produce a cured film.

[0111] Two cured films were placed on an aluminum cup filled with calcium chloride (anhydrous) as a desiccant, and further an aluminum ring was placed and screwed tightly. Then, the initial weight of the entire aluminum cup was measured. After that, the aluminum cup was put into a thermostatic chamber set at 60 °C and 90% Rh, and after 24 hours passed, the aluminum cup was taken out and weighed. The obtained weight value was substituted into the following calculation formula to calculate the moisture permeability. Calculation formula: Moisture permeability = (weight after test - weight before test) × film thickness / (film area × 100) And it was evaluated based on the following criteria. ◎: Moisture permeability is less than 25 g / m 2 ○: Moisture permeability is 25 g / m 2 or more and less than 30 g / m 2 ×: Moisture permeability is 30 g / m 2 or more If it is ○ or more, it is at a level with no practical problems and is judged to be good.

[0112] <Liquid crystal contamination> ​​The obtained liquid crystal sealant was applied onto a 40 mm × 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC) on which a transparent electrode and an alignment film were pre-formed, using a dispenser (Shot Master, manufactured by Musashi Engineering), to form a 35 mm × 35 mm square seal pattern (cross-sectional area 3500 μm 2 ) as the main seal and a 38 mm × 38 mm square seal pattern on its outer periphery. Next, a liquid crystal material (MLC-6609-000, manufactured by Merck) corresponding to the internal volume of the panel after bonding was precisely dropped into the frame of the main seal using a dispenser. Then, the paired glass substrates were bonded under reduced pressure and then opened to the atmosphere for bonding. And the two bonded glass substrates were held in a light-shielding box for 1 minute, and then, with the main seal masked with a substrate coated with a 36 mm × 36 mm square black matrix, light (light including visible light with 500 mJ / cm 2 and having a wavelength of 370 - 450 nm) was irradiated, and further heated at 120 °C for 1 hour to cure the main seal. After that, polarizing films were attached to both sides of the obtained liquid crystal cell to obtain a liquid crystal display panel. And the liquid crystal contamination was evaluated according to the following criteria. ◎: The liquid crystal is aligned until the main seal of the liquid crystal display panel, and there is no color unevenness at all. ○: Color unevenness occurs in a range less than 0.5 mm near the time of main seal. △: Color unevenness occurs in a range of 0.5 mm or more and less than 1 mm near the time of main seal. ×: Color unevenness occurs in a range of 1 mm or more from near the time of main seal. If it is △ or more, it is at a level with no practical problem and was judged to be good.

[0113] The evaluation results of the liquid crystal sealants of Examples 1 - 10 and Comparative Examples 1 - 2 are shown in Table 1.

[0114]

Table 1

[0115] As shown in Table 1, the liquid crystal sealants of Examples 1 to 10 containing alumina with an α - conversion rate of 80% or less all showed high adhesion strength to the substrate while maintaining a low moisture permeability.

[0116] In particular, it can be seen that by reducing the average particle size of alumina to 3.0 μm or less, color unevenness can be further reduced (comparison of Examples 1, 4, 5, and 8). Also, it can be seen that by setting the content of alumina below a certain level, color unevenness can be more effectively suppressed (comparison of Examples 1 to 3 and 7).

[0117] On the other hand, it can be seen that the liquid crystal sealant of Comparative Example 2 containing alumina (D - 3) with an α - conversion rate exceeding 80% has low adhesion strength to the substrate. Also, the liquid crystal sealant of Comparative Example 1 containing no alumina has a high moisture permeability and low adhesion strength to the substrate.

[0118] This application claims priority based on Japanese Patent Application No. 2022 - 048549 filed on March 24, 2022. All of the contents described in the specification of that application are incorporated herein by reference.

Industrial Applicability

[0119] The liquid crystal sealant of the present invention can form a seal member having high adhesion strength to the substrate while having high moisture resistance. Therefore, the liquid crystal sealant is very useful, especially as a liquid crystal sealant for the liquid crystal droplet method.

Claims

1. A liquid crystal sealant comprising a curable compound (A), a thermosetting agent (B), and alumina (D) having a gelatinization rate of 80% or less. The curable compound (A) contains 5 to 20 parts by mass of a thermosetting compound (A1) having an epoxy group in the molecule with respect to 100 parts by mass of the curable compound (A) (however, the thermosetting compound (A1) does not contain partial epoxy (meth)acrylate (A3)). Liquid crystal sealant.

2. The average particle diameter of the alumina (D) is 0.01 to 3 μm. The liquid crystal sealant according to Claim 1.

3. The content of the alumina (D) is 1 to 20 parts by mass with respect to 100 parts by mass of the curable compound (A). The liquid crystal sealant according to Claim 1.

4. The aspect ratio of the alumina (D) is 2.0 or less. The liquid crystal sealant according to Claim 1.

5. The alumina (D) is in particulate form. The liquid crystal sealant according to Claim 1.

6. The content of the thermosetting compound (A1) is 10 to 20 parts by mass with respect to 100 parts by mass of the curable compound (A). The liquid crystal sealant according to Claim 1.

7. The content of the thermosetting agent (B) is 10 parts by mass or more with respect to 100 parts by mass of the curable compound (A). The liquid crystal sealant according to Claim 1.

8. The thermosetting agent (B) contains at least one selected from the group consisting of dihydrazide-based thermally latent curing agents, imidazole-based thermally latent curing agents, amine adduct-based thermally latent curing agents, and polyamine-based thermally latent curing agents. The liquid crystal sealant according to Claim 1.

9. As the curable compound (A), a compound (A2) having an ethylenically unsaturated double bond in the molecule (however, the compound (A2) does not contain partial epoxy (meth)acrylate (A3)), And a photopolymerization initiator (C). Further comprising. The content ratio (A1 / A2) of the thermosetting compound (A1) and the compound (A2) is 30 / 70 to 50 / 50 (mass ratio). The liquid crystal sealant according to Claim 1.

10. As the curable compound (A), further containing partial epoxy (meth)acrylate (A3). The liquid crystal sealant according to Claim 1 or 9.

11. The photopolymerization initiator (C) contains at least one selected from the group consisting of oxime ester-based compounds, thioxanthone-based compounds, and anthraquinone-based compounds. The liquid crystal sealant according to Claim 9.

12. Further comprising a coupling agent. The liquid crystal sealing agent according to claim 1.

13. A liquid crystal sealing agent for the liquid crystal droplet method, The liquid crystal sealing agent according to claim 1.

14. A step of forming a seal pattern of the liquid crystal sealing agent according to claim 1 on one substrate, A step of dropping liquid crystal within the region of the seal pattern or on the other substrate paired with the one substrate while the seal pattern is in an uncured state, A step of superposing the one substrate and the other substrate via the seal pattern, A step of curing the seal pattern, including A method for manufacturing a liquid crystal display panel.

15. The step of curing the seal pattern includes a step of irradiating the seal pattern with light to cure the seal pattern, The method for manufacturing a liquid crystal display panel according to claim 14.

16. The light irradiated on the seal pattern includes light in the visible light region, The method for manufacturing a liquid crystal display panel according to claim 15.

17. The step of curing the seal pattern further includes a step of heating and curing the seal pattern irradiated with light, The method for manufacturing a liquid crystal display panel according to claim 16.

18. A pair of substrates, A frame-shaped seal member disposed between the pair of substrates, A liquid crystal layer filled in a space surrounded by the seal member between the pair of substrates including wherein the seal member includes a cured product of the liquid crystal sealing agent according to claim 1, A liquid crystal display panel.

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