KR20230133373A - Photocurable resin composition, liquid crystal sealing agent, liquid crystal display panel using the same, and method for manufacturing the same - Google Patents

Abstract

The object is to provide a photocurable resin composition capable of forming a sealing member with high adhesive strength to a substrate and low moisture permeability. The photocurable resin composition that solves the problem contains a curable compound (A) having an ethylenically unsaturated double bond in the molecule, a photopolymerization initiator (B), organic fine particles (C), and a coupling agent (D). The coupling agent (D) is a coupling agent having at least one chemical structure selected from the group consisting of butadiene rubber, butadiene styrene rubber, acrylic rubber, and silicone rubber.

Description

Photocurable resin composition, liquid crystal sealing agent, liquid crystal display panel using the same, and method for manufacturing the same

The present invention relates to a photocurable resin composition, a liquid crystal sealing agent, a liquid crystal display panel using the same, and a method of manufacturing the same.

A liquid crystal display panel usually has a pair of substrates, a frame-shaped sealing member disposed between them, and liquid crystal filled in an area surrounded by the two substrates and the sealing agent. In such a liquid crystal display panel, it is common for each of the two substrates to have an alignment film on its surface to orient the liquid crystal in a desired direction. Additionally, in a conventional liquid crystal display panel, a liquid crystal sealing agent was applied to the outer circumferential side of the alignment film to form a sealing member.

However, in recent years, narrow liquid softening of liquid crystal display panels has been required, and it has been required to form a sealing member also on the alignment film of the substrate. The alignment film is often hydrophobic and has fewer hydrophilic functional groups compared to a glass substrate or the like. Therefore, when a sealing member is placed on the alignment film, the adhesive strength between the substrate and the sealing member is not sufficient, and there are cases where peeling occurs at their interface. Therefore, a liquid crystal sealing agent containing an alkylbenzenesulfonic acid type titanate coupling agent has been proposed (for example, patent document 1).

Japanese Patent Publication No. 2014-219589

However, in the liquid crystal sealing agent described in Patent Document 1, the adhesive strength between the substrate having an alignment film and the sealing member is sometimes insufficient, and it has been required to further increase their adhesive strength.

Here, the sealing member is obtained by polymerizing or crosslinking a curable compound having photocurability and/or thermosetting properties. Therefore, it is conceivable to increase the flexibility of the sealing member by increasing the distance between the crosslinking points between the curable compounds, thereby relieving the stress applied to the interface between the sealing member and the substrate. However, in this method, since the distance between the crosslinking points of the curable compounds is long, there is a problem that moisture easily enters through the gap between them under conditions of high temperature and high humidity.

The present invention has been made in view of the above problems. Specifically, the purpose is to provide a photocurable resin composition capable of forming a sealing member with high adhesive strength to a substrate and high moisture resistance, a liquid crystal sealing agent containing the same, a liquid crystal display panel using the same, and a method for manufacturing the same. do.

The present invention provides the following photocurable resin composition and liquid crystal sealing agent.

[1] A photocurable resin composition containing a curable compound (A) having an ethylenically unsaturated double bond in the molecule, a photopolymerization initiator (B), organic fine particles (C), and a coupling agent (D), wherein the coupling agent (D) ) is a coupling agent having at least one chemical structure selected from the group consisting of butadiene rubber, butadiene styrene rubber, acrylic rubber, and silicone rubber.

[2] The photocurable resin composition according to [1], wherein the coupling agent (D) is a silane coupling agent having a butadiene rubber structure.

[3] The coupling agent (D) contains an alkoxysilyl group, and the amount of the alkoxysilyl group derived from the coupling agent (D) in 100 g of the photocurable resin composition is 1.0 × 10 ^-5 mol or more and 5.0 × 10 ^-3 mol or less, the photocurable resin composition described in [2].

[4] The photocurable resin composition according to any one of [1] to [3], wherein the content of the coupling agent (D) is 0.5 to 5 parts by mass based on a total amount of 100 parts by mass of the photocurable resin composition.

[5] It further contains at least one latent heat curing agent (E) selected from the group consisting of dihydrazide-based thermal latent curing agents, amine adduct-based thermal latent curing agents, and polyamine-based thermal latent curing agents. , the photocurable resin composition according to any one of [1] to [4].

[6] [1] to [5] which further contains an inorganic filler (F), and the content of the inorganic filler (F) is 5 to 15 parts by mass with respect to 100 parts by mass of the total amount of the photocurable resin composition. The photocurable resin composition according to any one of the above.

[7] A liquid crystal sealing agent containing the photocurable resin composition according to any one of the above [1] to [6].

The present invention provides a method for manufacturing the following liquid crystal display panel.

[8] A step of applying the liquid crystal sealing agent described in [7] above in a pattern to at least one of a pair of substrates to form a sealing pattern, and in an uncured state of the sealing pattern, a step of dropping liquid crystal on the area surrounded by the sealing pattern and/or the other substrate; a step of overlapping the one substrate and the other substrate with the sealing pattern and the liquid crystal interposed; and the sealing pattern. A method of manufacturing a liquid crystal display panel including a curing process.

[9] The method for manufacturing a liquid crystal display panel according to [8], wherein at least one of the pair of substrates has an alignment film on a surface in contact with the liquid crystal.

[10] The method for manufacturing a liquid crystal display panel according to [8] or [9], wherein in the step of curing the sealing pattern, light is irradiated to the sealing pattern.

[11] The method for manufacturing a liquid crystal display panel according to any one of [8] to [10], wherein in the step of curing the sealing pattern, the sealing pattern is irradiated with light and then heated.

[12] The method for manufacturing a liquid crystal display panel according to [10] or [11], wherein the light irradiated to the sealing pattern includes light in the visible light region.

The present invention provides the following liquid crystal display panel.

[13] A liquid crystal display panel including a pair of substrates, a sealing member on a frame disposed between the pair of substrates, and liquid crystal disposed inside the pair of substrates and the sealing member, comprising: A liquid crystal display panel in which the sealing member is a cured product of the liquid crystal sealing agent described in [7].

According to the photocurable resin composition of the present invention, a sealing member having high adhesive strength with a substrate and high moisture resistance can be formed.

In this specification, the numerical range indicated using “~” means a range that includes the numerical values written before and after “~” as the lower limit and upper limit. In this specification, when multiple substances corresponding to each component exist in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. In the numerical range described stepwise in this specification, the upper limit or lower limit value described in one numerical range may be replaced with the upper limit or lower limit value of another numerical range described stepwise. In this specification, the term “process” is included in this term not only as an independent process, but also in cases where the process cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

1. Photocurable resin composition

The photocurable resin composition of the present invention contains a curable compound (A) having an ethylenically unsaturated double bond in the molecule, a photopolymerization initiator (B), organic fine particles (C), and a coupling agent (D).

In a conventional photocurable resin composition (liquid crystal sealing agent), a functional group present on the surface of the substrate and a compound in the photocurable resin composition covalently bond, thereby forming a cured product of the substrate and the photocurable resin composition (hereinafter referred to as “sealing member”). (also referred to as ") was firmly attached. However, when the substrate has an alignment film on its surface, the covalent bond is not sufficiently formed, and the adhesive strength between the substrate and the sealing member cannot be sufficiently increased. Additionally, if an attempt is made to increase the stress on the substrate and the sealing member by reducing the crosslinking density of the sealing member and increasing the flexibility of the sealing member, the moisture resistance of the sealing member is likely to be lowered, which may have an effect on liquid crystal, etc.

In contrast, in the photocurable resin composition of the present invention, the coupling agent (D) is at least one chemical agent selected from the group consisting of butadiene rubber, butadiene styrene rubber, acrylic rubber, and silicone rubber. It is a coupling agent with a structure. When the sealing member is formed, such a coupling agent (D) is largely oriented at the interface between the substrate and the sealing member. The main causes of peeling between the sealing member and the substrate include residual stress generated during curing of the photocurable resin composition (liquid crystal sealing agent) and peeling stress in the direction of peeling the substrate and the sealing member. When the ring agent (D) exists between the sealing member and the substrate, the rubber-derived structure relieves the residual stress and peeling stress. On the other hand, the coupling agent (D) exerts its effect by adding a small amount. Therefore, it is difficult for the coupling agent (D) to affect the crosslinking structure or crosslinking density of the curable compound (A), and the moisture resistance of the sealing member can be kept high.

Hereinafter, each component in the photocurable resin composition of the present invention will be described in detail.

1-1. Curable Compound (A)

The curable compound (A) may be a compound having an ethylenically unsaturated double bond in the molecule. The curable compound (A) may be a monomer, oligomer, or polymer. Examples of the curable compound (A) 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. In this specification, the description of a (meth)acryloyl group means an acryloyl group or a methacryloyl group, or both. Additionally, the term (meth)acrylate means acrylate or methacrylate, or both. Furthermore, the term (meth)acrylic refers to either acrylic or methacrylic, or both.

Examples of the curable compound (A) containing one (meth)acryloyl group in one molecule include (meth)acrylic acid, such as methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid 2-hydroxyethyl ester. Acrylic acid alkyl esters are included.

Examples of the curable compound (A) having two or more (meth)acryloyl groups in one molecule include di(meth)acrylates derived from polyethylene glycol, propylene glycol, polypropylene glycol, etc.; Di(meth)acrylate derived from tris(2-hydroxyethyl)isocyanurate; Diol-derived di(meth)acrylate obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol; Diol-derived di(meth)acrylate obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A; Dior tri(meth)acrylate derived from triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane; Diol-derived di(meth)acrylate 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; These include neopentyl glycol, trimethylolpropane, and oligo(meth)acrylate of pentaerythritol.

The curable compound (A) may further have an epoxy group in the molecule. The number of epoxy groups per molecule may be 1 or 2 or more. If the curable compound (A) additionally has an epoxy group as well as a (meth)acryloyl group in the molecule, the photocurable resin composition can be cured even by heat. In other words, it becomes possible to use photocuring and thermal curing together. If the photocurable resin composition has photocurability and thermosetting properties, it becomes possible to efficiently cure the photocurable resin composition in a short time.

Examples of the curable compound (A) having a (meth)acryloyl group and an epoxy group in the molecule include (meth)acrylic acid glycidyl ester obtained by reacting an epoxy compound and (meth)acrylic acid in the presence of a basic catalyst.

The epoxy compound to be reacted with (meth)acrylic acid may be a polyfunctional epoxy compound having two or more epoxy groups in the molecule. From the viewpoint of suppressing the crosslinking density from becoming too high and the adhesion of the cured product of the photocurable resin composition from decreasing, 2 Functional epoxy compounds are preferred. Examples of bifunctional epoxy compounds include bisphenol type epoxy compounds (bisphenol A type, bisphenol F type, 2,2'-diallyl bisphenol type A, bisphenol AD type, and hydrogenated bisphenol type, etc.), biphenyl type epoxy compounds, and naphthalene-type epoxy compounds. Among them, bisphenol type epoxy compounds of bisphenol A type and bisphenol F type are preferable from the viewpoint of improving the applicability of the photocurable resin composition. The curable compound (A) derived from a bisphenol-type epoxy compound has advantages such as superior applicability compared to the curable compound (A) derived from a biphenyl ether-type epoxy compound.

On the other hand, the curable compound (A) may contain only one type of the above compound, or may contain two or more types. In particular, the curable compound (A) includes a compound (A1) that has a (meth)acryloyl group in the molecule and no epoxy group, and a compound (A2) that has a (meth)acryloyl group and an epoxy group in the molecule. desirable. For example, when the photocurable resin composition further contains other curable compounds (for example, epoxy compounds) described later, compound (A1) and the epoxy compound may have low compatibility. On the other hand, when the compound (A2) having an epoxy group is combined, the compatibility of the curable compound (A) with other resins in the photocurable resin composition increases. Additionally, in general, when a photocurable resin composition is used as a liquid crystal sealing agent, hydrophobic compounds (e.g., epoxy compounds, etc.) are more likely to be eluted into the liquid crystal than hydrophilic compounds, but compound (A1) and compound (A2) are combined. By doing so, the elution of the epoxy compound into the liquid crystal becomes easier to suppress. The content ratio of compound (A2) and compound (A1) is preferably A2/A1 = 1/0.4 to 1/1.2, more preferably 1/0.8 to 1/1.2, and still more preferably 1/0.9 to 1/1.1. do.

On the other hand, the content of the compound (A2) having a (meth)acryloyl group and an epoxy group in the molecule is not particularly limited, but is preferably 30% by mass or more relative to the total amount of the curable compound (A).

In addition, in any of the above-mentioned curable compounds (A), the weight average molecular weight is preferably about 310 to 1000. The weight average molecular weight of the curable compound (A) can be measured in polystyrene conversion by, for example, gel permeation chromatography (GPC).

The content of the curable compound (A) is preferably 40 to 80% by mass, and more preferably 50 to 75% by mass, relative to the total amount of the photocurable resin composition. If the amount of the curable compound (A) is within the range, the strength of the resulting cured product (for example, a sealing member) can be increased, and the adhesion between the substrate and the cured product (for example, a sealing member) can be improved.

1-2. Photopolymerization initiator (B)

The photopolymerization initiator is not particularly limited as long as it is a compound capable of radically polymerizing the curable compound (A) by irradiation of light. For example, a self-cleavage type photopolymerization initiator may be used, or a hydrogen abstraction type photopolymerization initiator may be used.

Examples of self-cleavable photopolymerization initiators include alkylphenone-based compounds (e.g., benzyl dimethyl ketal such as 2,2-dimethoxy-1,2-diphenylethan-1-one (manufactured by BASF, IRGACURE 651), etc. ; α-aminoalkylphenones such as 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one (BASF, IRGACURE 907); 1-hydroxy-cyclohexyl-phenyl-ketone (BASF) α-hydroxyalkylphenone, such as manufactured by IRGACURE 184), acyl phosphine oxide-based compounds (e.g., 2,4,6-trimethylbenzoin diphenylphosphine oxide, etc.), and titanocene-based compounds (e.g., For example, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, etc.), acetope Non-based compounds (e.g. diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy- 2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-mo Polyno (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, etc.), phenyl glyoxylate-based compounds (e.g. For example, methylphenyl glyoxy ester, etc.), benzoin ether compounds (for example, benzoin, benzoin methyl ether, benzoin isopropyl ether, etc.), and oxime ester compounds (for example, 1,2-octanedione) -1-[4-(phenylthio)-2-(O-benzoyloxime)] (manufactured by BASF, IRGACURE OXE01), ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H- Carbazol-3-yl]-1-(0-acetyloxime) (manufactured by BASF, IRGACURE OXE02, etc.) is included.

Examples of hydrogen abstraction type photopolymerization initiators include benzophenone-based compounds (e.g., benzophenone, o-benzoylbenzoic acid methyl-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4- Benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 3,3'-dimethyl-4-methoxy benzophenone, etc.), thioxanthone-based compounds (e.g., thioxanthone, 2-chlorothioxanthone (manufactured by Tokyo Chemical Industry Co., Ltd.), 1-chloro-4-propoxythioxanthone, 1-chloro-4-ethoxy Thioxanthone (Speedcure CPTX, manufactured by Lambson Limited), 2-isopropyl thioxanthone (Speedcure ITX, manufactured by Lambson Limited), 4-isopropyl thioxanthone, 2,4-dimethylthioxanthone, 2,4- Diethylthioxanthone (Speedcure DETX, manufactured by Lambson Limited, 2,4-dichlorothioxanthone, etc.), anthraquinone-based compounds (e.g., 2-methylanthraquinone, 2-ethyanthraquinone, 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 Company), 2-hydroxy These include methylanthraquinone (Junsei Chemical Co., Ltd., 2-(Hydroxymethyl)anthraquinone) and benzyl-based compounds. The photocurable resin composition may contain only one type of photopolymerization initiator (B) or may contain two or more types of photopolymerization initiators (B).

The absorption wavelength of the photopolymerization initiator (B) is not particularly limited, and for example, a photopolymerization initiator (B) that absorbs light with a wavelength of 360 nm or more is preferable. Among these, a photopolymerization initiator (B) that absorbs light in the visible light region is more preferable, and light with a wavelength of 360 to 430 nm is particularly preferable. Meanwhile, in this specification, “visible light region” refers to the range of wavelength 360 nm to 780 nm.

Examples of the photopolymerization initiator (B) that absorbs light with a wavelength of 360 nm or more include alkylphenone-based compounds, acyl phosphine oxide-based compounds, titanocene-based compounds, oxime ester-based compounds, thioxanthone-based compounds, and anthraquinone-based compounds. , preferably an oxime ester-based compound.

Meanwhile, the structure of the photopolymerization initiator (B) can be specified by combining high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC/MS) with NMR measurement or IR measurement.

The molecular weight of the photopolymerization initiator (B) is preferably, for example, 200 or more and 5,000 or less. If the molecular weight is 200 or more, the photopolymerization initiator (B) is unlikely to be eluted into the liquid crystal when the photocurable resin composition is used as a liquid crystal sealing agent. On the other hand, when the molecular weight is 5000 or less, compatibility with the curable compound (A) increases, and the curability of the photocurable resin composition tends to be good. The molecular weight of the photopolymerization initiator (B) is more preferably 230 or more and 3000 or less, and further preferably 230 or more and 1500 or less.

The molecular weight of the photopolymerization initiator (B) 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).

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

The amount of the photopolymerization initiator (B) is preferably 0.01 to 10% by mass relative to the curable compound (A) described above. If the amount of the photopolymerization initiator (B) is 0.01% by mass or more relative to the curable compound (A), the curability of the photocurable resin composition tends to be good. If the content of the photopolymerization initiator (B) is 10% by mass or less, it becomes difficult for the photopolymerization initiator (B) to elute into the liquid crystal when the photocurable resin composition is used as a liquid crystal sealing agent. The content of the photopolymerization initiator (B) is more preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and particularly preferably 0.1 to 2.5% by mass, relative to the curable compound (A).

1-3. Organic particulates (C)

The type of organic fine particles (C) contained in the photocurable resin composition is not particularly limited, and examples of the organic fine particles (C) include silicon particles, acrylic particles, styrene particles such as styrene/divinyl benzene copolymer, and Polyolefin particles, etc. are included. The photocurable resin composition may contain only one type of organic fine particle (C) or may contain two or more types. The average primary particle diameter of the organic fine particles (C) is preferably 0.05 to 13 μm, more preferably 0.1 to 10 μm, and still more preferably 0.1 to 8 μm.

The shape of the organic fine particles (C) is not particularly limited, but is preferably spherical, and more preferably spherical. Spherical means that the ratio of the minimum value (b) of the diameter of each particle to the maximum value (a) is b/a = 0.9 to 1.0. The average primary particle size of the organic fine particles (C) can be measured by microscopy, specifically, image analysis using an electron microscope. Additionally, the surface of the organic fine particles (C) is preferably smooth. When the surface is smooth, the specific surface area decreases and the amount of organic fine particles (C) that can be added to the photocurable resin composition increases.

The content of the organic fine particles (C) is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 20 parts by mass, and still more preferably 0.3 to 15 parts by mass, with respect to 100 parts by mass of the photocurable resin composition. If the amount of organic fine particles (C) is within the range, the elastic modulus of the photocurable resin composition after photocuring is likely to fall within the desired range.

1-4. Coupling agent (D)

The coupling agent (D) has at least one chemical structure (hereinafter also referred to as “rubber structure”) selected from the group consisting of butadiene rubber, butadiene styrene rubber, acrylic rubber, and silicone rubber, and a liquid crystal Any compound having a group capable of reacting with a functional group present on the surface of the display panel substrate may be sufficient. Examples of the coupling agent (D) include compounds in which an organometallic compound having a group capable of reacting with a functional group present on the surface of the substrate of the liquid crystal display panel is bonded to the side chain or main chain of the rubber structure.

Examples of the coupling agent (D) include a silane coupling agent in which the organometallic compound is a silane-based compound, a titanate coupling agent in which the organometallic compound is a titanate-based compound, and a zirconate-based compound in which the organometallic compound is a titanate-based compound. These include phosphorus zirconate coupling agents, zirconium aluminate coupling agents in which the organometallic compound is a zirconium aluminate-based compound, and aluminate coupling agents in which the organometallic compound is an aluminate-based compound. Among these, silane coupling agents are particularly preferable from the viewpoint of availability, cost, etc. In organometallic compounds, the types of functional groups that bind to metals, that is, groups that can react with the functional groups present on the substrate surface of the liquid crystal display panel, are not particularly limited, and examples include alkoxy groups capable of polycondensation, such as OH groups on the substrate surface, etc. This is included.

Here, when the coupling agent (D) is a silane coupling agent, the amount of alkoxysilyl group derived from the coupling agent (D) in 100 g of the photocurable resin composition is 1.0 × 10 ^-5 mol or more and 5.0 × 10 ^-3 mol or less. is preferable, 2.5×10 ^{-5 mol} to 1.0×10 ^-3 mol is more preferable, and 5.0×10 ^-5 mol or more and 8.0×10 ^-4 mol or less is more preferable. If the amount of alkoxysilyl group derived from the coupling agent (D) in 100 g of the photocurable resin composition (hereinafter, the unit is also described as "mol/100g") is 5.0 × 10 ^-5 mol/100g or more, the alkoxysilyl group The group forms a siloxane bond with the OH group on the surface of the liquid crystal display panel, etc., and the resulting sealing member does not become excessively hard, making it easy to relieve residual stress, etc., generated during curing of the photocurable resin composition. Therefore, the adhesive strength between the resulting sealing member and the substrate increases. On the other hand, if the amount of the alkoxysilyl group derived from the coupling agent (D) is 8.0 × 10 ^-4 mol/100 g or less, the cured product of the photocurable resin composition obtained will not be excessively soft, and it will be difficult to deteriorate moisture permeability.

On the other hand, the amount of alkoxysilyl group derived from the coupling agent (D) in the photocurable resin composition is calculated from the following formula.

Amount of alkoxysilyl group = {(Amount (g) of coupling agent (D) having an alkoxysilyl group in 100 g of photocurable resin)/(Molecular weight of the coupling agent (D))}×(Alkoxy in the coupling agent (D) number of silyl groups)

Examples of silane-based compounds that are organometallic compounds include compounds represented by the following structures.

[Formula 1]

On the other hand, the rubber structure contained in the coupling agent (D) is not particularly limited, and may be any structure of butadiene rubber, butadiene styrene rubber, acrylic rubber, or silicone rubber, and the coupling agent (D) may be of any structure. A plurality of these structures may be contained in one molecule. Among them, a coupling agent (D) having a butadiene rubber structure is preferable from the viewpoint of versatility and the like.

The number average molecular weight of the coupling agent (D) is preferably 1,000 to 1,000,000, and more preferably 2,000 to 1,000,000. If the molecular weight of the coupling agent (D) is 1000 or more, the rubber structural portion of the coupling agent (D) becomes sufficiently large to reduce, for example, the stress between the sealing member and the substrate or the residual stress that occurs during curing of the photocurable resin composition. It becomes easy to alleviate sufficiently. On the other hand, if the molecular weight of the coupling agent (D) is 1,000,000 or less, the gap between the crosslinking points of the curable compound (A) is unlikely to be excessively widened by the coupling agent (D), and the moisture resistance of the sealing member can be improved. there is.

The number average molecular weight is a value (styrene conversion value) determined by gel permeation chromatography (GPC) using toluene, tetrahydrofuran, chloroform, etc. as a developing solvent.

Here, specific examples of the coupling agent (D) include compounds obtained by reacting a polybutadiene compound and an organosilane-based compound and represented by the following chemical formula.

[Formula 2]

The coupling agent (D) represented by the above formula includes a repeating unit derived from butadiene having a 2,3-vinyl structure, a repeating unit derived from butadiene having a 1,2-vinyl structure, and the 1,2- It includes a repeating unit in which a silane-based compound is bonded to the vinyl structure. The order of each repeating unit is not particularly limited.

In the above formula, x may be 0 or more, preferably 1 to 40, and more preferably 2 to 20. Moreover, y should just be 1 or more, preferably 1 to 40, and more preferably 2 to 20. z should just be 0 or more, preferably 0 to 10, and more preferably 0 to 5. a is an integer of 1 to 3, and 2 or 3 is more preferable.

R ¹ in the above formula is preferably a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms, and examples thereof include alkyl groups such as methyl group, ethyl group, and isopropyl group; Cycloalkyl groups such as cyclopentyl group; Alkenyl groups such as vinyl groups; Aryl groups such as phenyl group and tolyl group; Aralkyl groups such as benzyl group and 2-phenylethyl group; Halogenated alkyl groups such as 3-chloropropyl group; Cyanolated alkyl groups such as 2-cyanoethyl group; etc. are included. Among these, an alkyl group with 1 to 10 carbon atoms or an aryl group with 6 to 10 carbon atoms is preferable, an alkyl group is more preferable, and an ethyl group is particularly preferable.

On the other hand, R ² is preferably a substituted or unsubstituted hydrocarbon group having 1 to 12 carbon atoms, and examples thereof include alkyl groups such as methyl group, ethyl group, and isopropyl group; Cycloalkyl group; Alkenyl groups such as allyl groups; Aryl groups such as phenyl group and tolyl group; Aralkyl groups such as benzyl group and 2-phenylethyl group; Halogenated alkyl groups such as 3-chloropropyl group; Cyanolated alkyl groups such as 2-cyanoethyl group; Alkyl groups containing ether bonds such as methoxyethyl groups; etc. are included. Among these, an alkyl group with 1 to 10 carbon atoms or an aryl group with 6 to 10 carbon atoms is preferable, an alkyl group is more preferable, and a methyl group is particularly preferable.

The content of the coupling agent (D) is preferably 0.5 to 5 parts by mass, more preferably 1 to 4 parts by mass, and still more preferably 1 to 3 parts by mass, with respect to 100 parts by mass of the photocurable resin composition. When the amount of the coupling agent (D) is 1 part by mass or more, the adhesive strength, etc. between the sealing member and the substrate obtained from the photocurable resin composition increases. On the other hand, if the amount of the coupling agent (D) is 5 parts by mass or less, it is difficult to affect the gap between the crosslinking points of the curable compound (A), and the moisture resistance of the sealing member becomes good.

1-5. Latent thermosetting agent (E)

The photocurable resin composition preferably further contains a latent thermosetting agent (E). The latent thermosetting agent (E) is a compound that does not cure the curable compound (A) or other curable compounds described later under normal storage conditions (room temperature, under visible light, etc.), but hardens these compounds when heated. . In other words, if the photocurable resin composition contains a latent thermosetting agent (E), the photocurable resin composition becomes heat-curable. The latent thermosetting agent (E) is preferably, for example, a curing compound containing an epoxy group or a curing agent capable of curing an epoxy-based compound described later (hereinafter also referred to as an “epoxy curing agent”).

From the viewpoint of increasing the viscosity stability of the photocurable resin composition and not impairing the moisture resistance of the cured product, the epoxy curing agent preferably has a melting point of 50°C or more and 250°C or less, and more preferably has a melting point of 100°C or more and 200°C or less, 150°C or more and 200°C or less are more preferable.

Examples of epoxy curing agents include dihydrazide thermal latent curing agents, amine adduct thermal latent curing agents, polyamine thermal latent curing agents, dicyandiamide thermal latent curing agents, imidazole thermal latent curing agents, etc. This is included. The photocurable resin composition may contain only one type of these, or may contain two or more types.

Examples of dihydrazide-based thermal latent curing agents include adipic acid dihydrazide, 1,3-bis(hydrazinocarboethyl)-5-isopropylhydantoin, and 7,11-octadecadiene. -1,18-dicarbohydrazide, dodecanedioic acid dihydrazide, and sebacic acid dihydrazide.

The amine adduct-based thermal latent curing agent is a thermal latent curing agent composed of an addition compound obtained by reacting an amine-based compound having catalytic activity with an arbitrary compound. Examples of commercially available amine adduct-based thermal latent curing agents include Amicure PN-40, Amicure PN-23, Amicure PN-31, Amicure PN-H, Amicure MY-24, and Amicure MY-H. (all manufactured by Ajinomoto Fine Techno), etc.

The polyamine-based thermal latent curing agent is a thermal latent curing agent having a polymer structure obtained by reacting an amine and an epoxy resin. Examples of commercial products include Adeka Hardener EH4339S and Adeka Hardener EH4357S (both manufactured by ADEKA). do.

Examples of dicyandiamide-based thermal latent curing agents include dicyandiamide and the like.

Examples of imidazole-based thermal latent curing agents include 2,4-diamino-6-[2'-ethylimidazolyl-(1')]-ethyltriazine, and 2-phenylimidazole. .

Among the above, from the viewpoint of ease of availability, compatibility with other components, etc., a dihydrazide-based thermal latent curing agent, an amine adduct-based thermal latent curing agent, or a polyamine-based thermal latent curing agent is preferable. The latent thermosetting agent (C) may contain only one type of epoxy curing agent, or may contain two or more types.

The amount of the latent thermosetting agent (E) is preferably 3 to 30 parts by mass, more preferably 3 to 20 parts by mass, and still more preferably 5 to 20 parts by mass, relative to the total amount of 100 parts by mass of the photocurable resin composition. The photocurable resin composition may be a one-component curable resin composition. The one-component curable resin composition has excellent workability because there is no need to mix the base material and curing agent before use.

1-6. Inorganic Filler (F)

The photocurable resin composition may further contain an inorganic filler (F) as needed. When the photocurable resin composition contains an inorganic filler (F), the viscosity of the photocurable resin composition, the strength of the cured product, and linear expansion properties tend to be good.

Examples of inorganic fillers (F) include calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, titanium nitride, aluminum oxide (alumina), zinc oxide, silicon dioxide, titanic acid. These include potassium, kaolin, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, and silicon nitride. Among them, silicon dioxide and talc are preferable.

The shape of the inorganic filler (F) may be a regular shape, such as a spherical shape, a plate shape, or a needle shape, or may be an irregular shape. When the inorganic filler (F) is spherical, the average primary particle diameter of the inorganic filler (F) is preferably 1.5 μm or less, and the specific surface area is more preferably 0.5 to 20 m ² /g. The average primary particle diameter of the inorganic filler (F) can be measured by the laser diffraction method described in JIS Z8825-1. The specific surface area of the filler can be measured by the BET method described in JIS Z8830.

The amount of the inorganic filler (F) is preferably 5 to 15 parts by mass with respect to 100 parts by mass of the total amount of the photocurable resin composition. If the amount of the inorganic filler (F) is 5 parts by mass or more, the moisture resistance of the cured product (sealing member) of the photocurable resin composition is likely to increase, and if the amount is 10 parts by mass or less, the coating stability of the photocurable resin composition is unlikely to be impaired. The content of the inorganic filler (F) is more preferably 5 to 10 parts by mass relative to the photocurable resin composition.

1-7. Other curable compounds

The photocurable resin composition may further contain a thermosetting compound. However, the thermosetting compound is a different compound from the curable compound (A) described above.

Examples of thermosetting compounds include epoxy compounds having an epoxy group in the molecule. The epoxy compound may be a monomer, oligomer, or polymer. When the photocurable resin composition contains an epoxy compound, the display characteristics of the resulting liquid crystal panel improve and the moisture resistance of the cured product (sealing member) increases.

It is particularly preferable that the epoxy compound has an aromatic ring. Moreover, the weight average molecular weight of the epoxy compound is preferably 500 to 10,000, and more preferably 1,000 to 5,000. The weight average molecular weight of the epoxy compound is measured in polystyrene conversion by gel permeation chromatography (GPC).

Examples of aromatic epoxy compounds include aromatic diols represented by bisphenol A, bisphenol S, bisphenol F, and bisphenol AD, and these aromatic diols are modified with ethylene glycol, propylene glycol, alkylene glycol, etc. An aromatic polyvalent glycidyl ether compound obtained by reaction of a diol with epichlorohydrin; novolak-type polyvalent glycidyl ether compounds obtained by the reaction of polyphenols such as novolac resins derived from phenol or cresol and formaldehyde, polyalkenylphenols and copolymers thereof, and epichlorohydrin; Glycidyl ether compounds of xylylene phenol resin are included. Among them, cresol novolak-type epoxy compounds, phenol novolak-type epoxy compounds, bisphenol A-type epoxy compounds, bisphenol F-type epoxy compounds, triphenolmethane-type epoxy compounds, triphenolethane-type epoxy compounds, trisphenol-type epoxy compounds, Dicyclopentadiene type epoxy compounds, diphenyl ether type epoxy compounds or biphenyl type epoxy compounds are preferred. The photocurable resin composition may contain only one type of epoxy compound or may contain two or more types.

The epoxy compound may be liquid or solid. From the viewpoint of easily increasing the moisture resistance of the cured product, a solid epoxy compound is preferable. The softening point of the solid epoxy compound is preferably 40°C or higher and 150°C or lower. The softening point can be measured by the ring and ball method specified in JIS K7234.

The content of the thermosetting compound is preferably 3 to 20 parts by mass with respect to 100 parts by mass of the photocurable resin composition. When the amount of the thermosetting compound is 3 parts by mass or more, the moisture resistance of the cured product (sealing member) of the photocurable resin composition is likely to be improved well. If the content of the thermosetting compound is 20 parts by mass or less, an excessive increase in viscosity is unlikely to occur in the photocurable resin composition. The amount of the thermosetting compound is more preferably 3 to 15 parts by mass, and more preferably 4 to 15 parts by mass, per 100 parts by mass of the photocurable resin composition.

The content of the thermosetting compound is preferably 3.8 to 50 parts by mass, more preferably 5 to 30 parts by mass, per 100 parts by mass of the curable compound (A). When the content of the thermosetting compound relative to the curing compound (A) is 3.8 parts by mass or more, the moisture resistance of the cured product and the adhesive strength to the glass substrate further increase. On the other hand, if it is 50 parts by mass or less, compatibility with the curable compound (A) during production tends to be good.

1-8. other compounds

The photocurable resin composition of the present invention may optionally contain a thermal radical polymerization initiator, a silane coupling agent other than the coupling agent (D) described above, an ion trap agent, an ion exchange agent, a leveling agent, a pigment, a dye, a sensitizer, and a plasticizer. and additives such as antifoaming agent may be further included.

Examples of silane coupling agents include vinyl trimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxy. Silane, etc. are included. 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 curable compound (A). When the content of the silane coupling agent is 0.01 parts by mass or more, the cured product of the photocurable resin composition tends to be higher.

The photocurable resin composition of the present invention may further contain a spacer or the like for adjusting the gap of the liquid crystal display panel.

The total amount of other components is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the total amount of the photocurable resin composition. If the total amount of other components is 50 parts by mass or less, the viscosity of the photocurable resin composition is unlikely to increase excessively, and the coating stability of the photocurable resin composition is unlikely to be impaired.

1-9. Physical properties of photocurable resin composition

The viscosity of the photocurable resin composition of the present invention at 25°C and 2.5 rpm with an E-type viscometer is preferably 200 to 450 Pa·s, and more preferably 300 to 400 Pa·s. If the viscosity is within the above range, the applicability of the photocurable resin composition using a dispenser becomes good.

The photocurable resin composition of the present invention can be used as a sealing agent as described above. The photocurable resin composition is particularly suitable as a display element sealing agent used for encapsulating display elements such as liquid crystal display elements, organic EL elements, and LED elements. In addition, since the photocurable resin composition of the present invention is difficult to contaminate liquid crystal, it is very suitable as a liquid crystal sealing agent for the liquid crystal dropping method.

2. Liquid crystal display panel and method of manufacturing the same

The liquid crystal display panel of the present invention includes a pair of substrates (display substrate and counter substrate) each having an alignment film, a sealing member on a frame disposed between the alignment films of the pair of substrates, and a space between the pair of substrates. It includes a liquid crystal layer filled in the space surrounded by the sealing member. The sealing member is a cured product of the photocurable resin composition (liquid crystal sealing agent) described above.

Both the display substrate and the opposing 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.

A matrix TFT, color filter, black matrix, etc. may be disposed on the surface of the display substrate or the opposing substrate. An alignment film is additionally disposed on the surface of the display substrate or the opposing substrate. The alignment film contains a known organic or inorganic aligning agent.

As described above, sealing members obtained from general liquid crystal sealing agents may have low adhesion to these alignment films. In contrast, the photocurable resin composition (liquid crystal sealing agent) described above has an alkoxy group that reacts with the substrate surface, and the coupling agent (D) present near the interface with the substrate has a rubber structure in its molecular structure. , In particular, at the interface between the fragile substrate and the sealing member, residual stress generated in the sealing member during curing can be alleviated, or external stress applied to the liquid crystal display panel can be absorbed. Therefore, even if the sealing member is placed in the area where the alignment film is formed, peeling is unlikely to occur at their interface. Therefore, in the liquid crystal display panel of the present invention, narrow liquid softening can be realized.

A liquid crystal display panel is manufactured using the liquid crystal sealing agent of the present invention. Methods for manufacturing a liquid crystal display panel generally include a liquid crystal dropping method and a liquid crystal injection method. However, the liquid crystal display panel of the present invention is preferably manufactured by the liquid crystal dropping method.

The manufacturing method of a liquid crystal display panel using the liquid crystal dropping method is:

1) A process of forming a sealing pattern by applying the above-described liquid crystal sealant in a pattern (frame shape) on the alignment film of one of a pair of substrates, each having an alignment film;

2) A process of dropping liquid crystal on one substrate, in an area surrounded by the sealing pattern, or on the other substrate when the sealing pattern is in an uncured state;

3) A process of overlapping one substrate and the other substrate with a sealing pattern and liquid crystal interposed,

4) Process of hardening the sealing pattern

Includes.

In step 1), a liquid crystal sealing agent is applied to the desired shape. The application method is not particularly limited and can be applied by any general method. Also, at this time, the width of the sealing pattern to be formed is not particularly limited, but the liquid crystal sealing agent described above has a high adhesive strength with the substrate. Therefore, it is also possible to set the width of the sealing agent to about 0.3 mm to 0.6 mm.

In step 2), the uncured state of the sealing pattern means a state in which the curing reaction of the liquid crystal sealing agent has not progressed to the gelation point. For this reason, in step 2), in order to suppress dissolution of the liquid crystal sealing agent into the liquid crystal, the sealing pattern may be semi-hardened by light irradiation or heating. One substrate and the other substrate are a display substrate or an opposing substrate, respectively. Additionally, when dropping the liquid crystal on the other substrate in step 2), the liquid crystal is dropped so that when the two substrates are overlapped in step 3), the liquid crystal enters the inside of the sealing pattern.

In the step 4), only curing by light irradiation may be performed, or curing by heating may be performed after curing by light irradiation. By performing curing by light irradiation, the liquid crystal sealing agent can be cured in a short time, so 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 compared to the case of curing only by light irradiation.

The light to be irradiated is appropriately selected depending on the type of photopolymerization initiator (B) in the above-mentioned liquid crystal sealing agent (photocurable resin composition), but light in the visible light range is preferable, for example, light with a wavelength of 370 to 450 nm is preferable. . This is because light of the above wavelength causes relatively little damage to the liquid crystal material or driving electrode. For irradiation of light, a known light source that emits ultraviolet rays or visible light can be used. When irradiating visible light, high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, xenon lamps, fluorescent lamps, etc. can be used.

The light irradiation energy may be any energy that can cure the curable compound (A). The photocuring time also depends on the composition of the liquid crystal sealing agent, but is, for example, about 10 minutes.

The heat curing temperature also depends on the composition of the liquid crystal sealing agent, but is, for example, 120°C, and the heat curing time is about 2 hours.

Example

Hereinafter, the present invention will be explained in more detail by examples. However, the scope of the present invention is not limited at all by these examples, and changes in the embodiments are possible without departing from the spirit of the present invention.

1. Preparation of materials

1-1. Preparation of curable compound (A)

The following curable compounds (A-1) to (A-4) were prepared.

Curable compound (A-1): Methacryl-modified bisphenol F-type epoxy resin prepared in Synthesis Example 1 below

Curable compound (A-2): Acrylic resin (Light Acrylate 14EG-A, manufactured by Kyoei Chemical Company)

Curable compound (A-3): Acrylic resin prepared in Synthesis Example 2 below

Curable compound (A-4): Methacryl-modified bisphenol F-type epoxy resin prepared in Synthesis Example 1 below

[Synthesis Example 1] Synthesis of curable compound (A-2)

160 g of liquid bisphenol F-type epoxy resin (Epototo YDF-8170C, manufactured by Doto Chemical Co., Ltd., epoxy equivalent weight 160 g/eq), 0.1 g of polymerization inhibitor (p-methoxyphenol), and 0.2 g of catalyst (triethanolamine). , 43.0 g of methacrylic acid was added into the flask, dry air was blown, and reaction was carried out for 5 hours while refluxing and stirring at 90°C. The obtained resin was washed 20 times with ultrapure water to obtain curable compound (A-2) (methacrylic acid-modified bisphenol F-type epoxy resin (partially modified methacrylate)).

[Synthesis Example 2] Synthesis of curable compound (A-3)

116 g of 2-hydroxyethyl acrylate, 0.1 g of polymerization inhibitor (p-methoxyphenol), and 100 g of succinic anhydride were placed in a flask, dry air was blown, and reaction was carried out for 5 hours while refluxing and stirring at 90°C. Subsequently, 170 g of bisphenol A diglycidyl ether was added, and the reaction was similarly performed for 5 hours while refluxing and stirring at 90°C. The obtained resin was washed 20 times with ultrapure water to obtain a curable compound (A-3).

[Synthesis Example 3] Synthesis of curable compound (A-4)

160 g of liquid bisphenol F-type epoxy resin (Epototo YDF-8170C, manufactured by Doto Chemical Co., Ltd., epoxy equivalent weight 160 g/eq), 0.1 g of polymerization inhibitor (p-methoxyphenol), and 0.2 g of catalyst (triethanolamine). , 81.7 g of methacrylic acid was added into the flask, dry air was blown, and reaction was carried out for 5 hours while refluxing and stirring at 90°C. The obtained resin was washed 20 times with ultrapure water to obtain curable compound (A-4) (methacrylic acid-modified bisphenol F-type epoxy resin (95 mol% partially modified methacrylate)).

1-2. Preparation of photopolymerization initiator (B)

As a photopolymerization initiator (B), IRGACURE OXE01, manufactured by BASF Japan, was prepared.

1-3. Preparation of organic particulates (C)

As organic fine particles (C), fine particle polymer F351, manufactured by Aika Kogyo Co., Ltd. was prepared.

1-4. Preparation of coupling agent (D)

The following coupling agents (D-1) and (D-2) were prepared.

· Coupling agent (D-1): A commercially available silane coupling agent represented by the following chemical formula (average molecular weight: 6000, number of alkoxysilyl groups: 1)

[Formula 3]

(In the above formula, R is an alkyl group)

· Coupling agent (D-2): Silane coupling agent (KBM-403, manufactured by Shin-Etsu Silicone, molecular weight: 236, number of alkoxysilyl groups: 1)

1-5. Preparation of latent thermosetting agent (E)

The following latent thermosetting agents (E-1) and (E-2) were prepared.

· Latent thermosetting agent (E-1): Adipic acid dihydrazide (ADH, manufactured by Nippon Chemical Company, melting point 177∼184℃)

· Latent thermosetting agent (E-2): Modified polyamine (EH-5030S, manufactured by ADEKA)

1-6. Preparation of inorganic filler (F)

Silica particles (S-100 manufactured by Nippon Shokubai Chemical Company) were prepared as an inorganic filler (F).

1-7. Preparation of other compounds

The following compounds were also prepared.

· Epoxy resin: YL983U, manufactured by Mitsubishi Chemical Corporation

· Polyisoprene rubber 1: UC-102, manufactured by Kuraray (weight average molecular weight: 17,000)

· Polyisoprene rubber 2: UC-203M, manufactured by Kuraray (weight average molecular weight: 35,000)

· Polybutadiene rubber: LBR-361, manufactured by Kuraray (weight average molecular weight: 5,500)

・Polystyrene butadiene rubber: Ricon100, manufactured by Cray Valley (weight average molecular weight: 4,500)

2. Preparation of resin composition

2-1. Example 1

8 parts by mass of epoxy resin, 54 parts by mass of curable compound (A-1) obtained in Synthesis Example 1, 2 parts by mass of curable compound (A-2) (polyethylene glycol diacrylate), and 2 parts by mass of curable compound (A-2) (polyethylene glycol diacrylate) obtained in Synthesis Example 2 5 parts by mass of the obtained curable compound (A-3), 5 parts by mass of the curable compound (A-4) obtained in Synthesis Example 3, 1 part by mass of the photopolymerization initiator (B), 12 parts by mass of the organic fine particles (C), 2 parts by mass of coupling agent (D-1), 5 parts by mass of latent thermosetting agent (E-1) (adipic acid dihydrazide), 6 parts by mass of inorganic filler (F) (silica particles), 3 rolls was sufficiently mixed to obtain a uniform composition to obtain a photocurable resin composition.

2-2. Examples 2 to 4, and Comparative Examples 1 to 5

A photocurable resin composition was produced in the same manner as in Example 1, except that the composition was changed as shown in Table 1.

3. Evaluation

For the photocurable resin compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 5, the amount of alkoxysilyl groups in the photocurable resin composition, compatibility, adhesive strength, and moisture permeability were evaluated by the following methods. The results are shown in Table 1.

3-1. Amount of alkoxysilyl group in photocurable resin composition

The amount of alkoxysilyl group (mol/100g) in 100g of the photocurable resin composition was determined as follows.

Amount of alkoxysilyl group (mol/100g) = {(Amount (g) of coupling agent (D) having alkoxysilyl group in 100g of photocurable resin)/(Molecular weight of the coupling agent (D))}×(Coupling agent (Number of alkoxysilyl groups in (D))

3-2. compatibility

As described above, the photocurable resin composition uniformly mixed using three rolls was placed in a container and left to stand for 10 minutes. After that, it was judged with the naked eye whether separation had occurred using the following criteria.

○: No separation

×: Separation is recognized

3-3. Adhesion strength test

The obtained photocurable resin composition is applied to one substrate of a pair of substrates (40 mm x 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC)) on which a transparent electrode and an alignment film have been previously formed, using a dispenser (Shot Master, manufactured by Musashi Engineering Co., Ltd.). It was applied in a frame shape to form a sealing pattern. The sealing pattern was formed in a square shape of 38 mm x 38 mm, with a cross-sectional area of 2500 μm ² (corresponding to 0.5 mm as the width of the frame). On the other hand, the frame width of the sealing material of recent liquid crystal displays is narrow, 1.8 mm, generally about 8 mm, and this test has strict conditions for an adhesive strength test with an extremely narrow line width. One glass substrate on which the sealing pattern was formed and the other glass substrate were bonded together under reduced pressure so that the directions of each other's alignment films were perpendicular, and then released to the atmosphere. Then, the two bonded glass substrates were held in a light-shielding box for 1 minute. After that, light containing visible light (light with a wavelength of 370 to 450 nm) was irradiated at 3000 mJ/cm ² and the photocurable resin composition was further cured by heating at 120° C. for 1 hour to obtain a test piece.

A press-fit tester (Model 210, manufactured by Intesco) was pressed vertically into a portion 4.5 mm from the corner of the sealing member of the obtained test piece at a speed of 5 mm/min, and the stress when the seal was peeled off was measured. The adhesive strength was obtained by dividing the stress by the line width of the sealing member. The adhesive strength was evaluated as follows.

○: In case of 15N/mm or more

△: In case of 10N/mm or more but less than 15N/mm

×: When less than 10N/mm

3-4. Moisture penetration measurement

The moisture permeation amount of the photocurable resin composition was measured by the moisture permeability cup method based on JIS:Z0208. Specifically, the photocurable resin composition described above was applied to a film thickness of 100 μm on release paper using an applicator. The release paper on which the coating film of the photocurable resin composition was formed was irradiated with 3 J/cm ² of ultraviolet light. After that, it was kept in a hot air drying oven at 120°C for 60 minutes, then taken out and cooled. Then, the coating film was peeled from the release paper to obtain a film with a thickness of 100 μm.

From the obtained 100 μm film, an aluminum cup was produced by a method based on JIS:Z0208, and left in a high temperature and high humidity tank at 60°C and 90%RH for 24 hours. And, from the mass before and after leaving in the high-temperature, high-humidity tank, the amount of moisture permeation was calculated using the following calculation formula.

Moisture penetration (g/m ² ·100μm·24h) = [Weight of aluminum cup after leaving for 24 hours (g) - Weight of aluminum cup before leaving (g)] / Film area (m ² )

Moisture permeability was evaluated based on the following standards.

○: When less than 100g/ ^m2 ·100μm·24h

△: When 100g/m ² ·100μm·24h or more and less than 130g/m ² ·100μm·24h

×: In case of 130g/m ² ·100μm·24h or more

As shown in Table 1, according to the photocurable resin composition containing the coupling agent (D-1) having a butadiene rubber structure, the adhesive strength with the substrate was high and moisture permeability was low (Examples 1 to 6) . In contrast, when the coupling agent did not have a rubber structure, the adhesive strength did not increase (Comparative Example 1). Moreover, even when various rubbers were added instead of the coupling agent, the adhesive strength was not sufficiently increased, and the moisture permeation amount also increased (Comparative Examples 2 to 5). Because the adhesive strength test is evaluated at a width narrower than the width of the frame of a conventional sealing material, it is believed that there is a significant difference between the Examples and Comparative Examples. Furthermore, even when the coupling agent without a rubber structure and the rubber were added separately, the adhesive strength decreased and the amount of moisture permeation was also large (Comparative Examples 6 and 7). Moreover, even if the amount of the coupling agent without a rubber structure was increased or decreased, it was difficult to achieve both reduction in adhesive strength and moisture permeability (Comparative Examples 8 and 9). On the other hand, in Comparative Example 9, although the amount of alkoxysilyl groups was large, the adhesive strength was thought to be low because there was no structure (rubber structure) to relieve stress.

This application claims priority based on Japanese Patent Application No. 2021-030188, filed on February 26, 2021. All contents described in the application specification are incorporated into the present application specification.

According to the photocurable resin composition of the present invention, a sealing member having high adhesive strength with a substrate and high moisture resistance can be formed. Therefore, the photocurable resin composition is very useful as a sealing agent for various display elements.

Claims (13)

A curable compound (A) having an ethylenically unsaturated double bond in the molecule,
Photopolymerization initiator (B),
Organic particulates (C), and
Coupling agent (D)
A photocurable resin composition containing,
The coupling agent (D) is a coupling agent having at least one chemical structure selected from the group consisting of butadiene rubber, butadiene styrene rubber, acrylic rubber, and silicone rubber,
Photocurable resin composition. According to claim 1,
The coupling agent (D) is a silane coupling agent having a butadiene rubber structure,
Photocurable resin composition. According to claim 2,
The coupling agent (D) contains an alkoxysilyl group,
The amount of the alkoxysilyl group derived from the coupling agent (D) in 100 g of the photocurable resin composition is 1.0 × 10 ^-5 mol or more and 5.0 × 10 ^-3 mol or less,
Photocurable resin composition. The method according to any one of claims 1 to 3,
The content of the coupling agent (D) is 0.5 to 5 parts by mass with respect to 100 parts by mass of the total amount of the photocurable resin composition,
Photocurable resin composition. The method according to any one of claims 1 to 4,
It further contains at least one latent heat curing agent (E) selected from the group consisting of a dihydrazide-based thermal latent curing agent, an amine adduct-based thermal latent curing agent, and a polyamine-based thermal latent curing agent,
Photocurable resin composition. The method according to any one of claims 1 to 5,
Additionally containing an inorganic filler (F),
The content of the inorganic filler (F) is 5 to 15 parts by mass with respect to 100 parts by mass of the total amount of the photocurable resin composition,
Photocurable resin composition. A liquid crystal sealing agent comprising the photocurable resin composition according to any one of claims 1 to 6. A step of applying the liquid crystal sealing agent according to claim 7 in a pattern to at least one of a pair of substrates to form a sealing pattern;
A process of dropping liquid crystal on an area surrounded by the sealing pattern of one substrate and/or the other substrate while the sealing pattern is in an uncured state;
A process of overlapping the one substrate and the other substrate with the sealing pattern and the liquid crystal interposed therebetween;
Process of curing the sealing pattern
Including,
Manufacturing method of liquid crystal display panel. According to claim 8,
At least one of the pair of substrates has an alignment film on a surface in contact with the liquid crystal,
Manufacturing method of liquid crystal display panel. According to claim 8 or 9,
In the process of curing the sealing pattern,
Irradiating light to the ceiling pattern,
Manufacturing method of liquid crystal display panel. The method according to any one of claims 8 to 10,
In the process of curing the sealing pattern,
After irradiating light to the sealing pattern, heating is performed.
Manufacturing method of liquid crystal display panel. The method of claim 10 or 11,
The light irradiated to the ceiling pattern includes light in the visible light region,
Manufacturing method of liquid crystal display panel. A liquid crystal display panel comprising a pair of substrates, a frame-shaped sealing member disposed between the pair of substrates, and liquid crystal disposed inside the pair of substrates and the sealing member,
The sealing member on the frame is a cured product of the liquid crystal sealing agent according to claim 7,
Liquid crystal display panel.