Resin composition, liquid crystal sealing agent, and liquid crystal display panel

Abstract

The present invention addresses the problem of providing a resin composition capable of forming a sealing material with high adhesion to various substrates and excellent moisture resistance when used as a liquid crystal sealing agent. A resin composition for solving the abovementioned problem includes: an epoxy resin having two or more epoxy groups in each molecule (excluding resins having a (meth)acryloyl group in each molecule); a (meth)acrylic-modified epoxy resin having an epoxy group and a (meth)acryloyl group in each molecule; a (meth)acrylic compound having one or more (meth)acryloyl groups in each molecule (excluding resins having an epoxy group in each molecule); and an imidazole-based compound. The amount of the imidazole-based compound is 4.0 mass% or more, and the ratio of the total number of epoxy groups in the resin composition to the total number of imidazole groups in the resin composition is 4.0 or more.

Description

Resin composition, liquid crystal sealant, and liquid crystal display panel

[0001] The present invention relates to a resin composition, a liquid crystal sealant, and a liquid crystal display panel.

[0002] Liquid crystal and organic electroluminescence (EL) display panels are widely used as image display panels for various electronic devices such as mobile phones and personal computers. For example, a liquid crystal display panel includes two transparent substrates each having an electrode on its surface, a frame-shaped sealant sandwiched between the substrates, and a liquid crystal material sealed within the region surrounded by the sealant.

[0003] Here, the encapsulant is required to have high adhesion to the substrate. If the encapsulant peels off from the substrate, liquid crystal leakage and poor image display occur. Therefore, conventionally, a compound having a hydrophilic group (e.g., a silane coupling agent) is included in the liquid crystal sealant used to form the encapsulant, and the hydrophilic groups in the encapsulant are chemically bonded to the hydrophilic groups present on the substrate surface, thereby improving adhesion. It has also been proposed to include core-shell particles in the liquid crystal sealant used to form the encapsulant (e.g., Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2005-15757

[0005] In a liquid crystal display panel, an alignment film is typically disposed on each surface of a pair of substrates to align the liquid crystal in a desired direction. Conventional liquid crystal display panels typically involve applying a liquid crystal sealant to the outer surface of the alignment film disposed on the substrates to form a sealant. Therefore, it is sufficient to increase the adhesion between the substrate and the sealant. As described above, this can be achieved by adding a silane coupling agent or by using core-shell particles.

[0006] However, in recent years, there has been a demand for narrower frame widths for liquid crystal display panels. Therefore, there is a need to apply a liquid crystal sealant to the area where the alignment film is located to form a sealant. However, recent alignment films are highly hydrophobic and have a small number of hydrophilic groups. In other words, the amount of groups capable of covalently bonding with hydrophilic groups in the liquid crystal sealant is small. Therefore, with conventional liquid crystal sealants, it has sometimes been difficult to sufficiently increase the adhesive strength between the sealant obtained by applying this and the substrate on which the alignment film is located. Furthermore, narrowing the frame width also requires narrowing the width of the sealant, which reduces the contact area between the substrate and the sealant, making it difficult to increase the adhesive strength. Furthermore, narrowing the width of the sealant also poses the problem of reduced moisture resistance.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a resin composition that, when used as a liquid crystal sealant, can form a sealant that has high adhesion to various substrates and excellent moisture resistance, and a liquid crystal sealant and a liquid crystal display panel using the same.

[0008] The present invention provides the following resin compositions. [1] A resin composition comprising an epoxy resin having two or more epoxy groups in the molecule (excluding resins having a (meth)acryloyl group in the molecule), a (meth)acrylic-modified epoxy resin having an epoxy group and a (meth)acryloyl group in the molecule, a (meth)acrylic compound having one or more (meth)acryloyl groups in the molecule (excluding resins having an epoxy group in the molecule), and an imidazole compound, wherein the amount of the imidazole compound is 4.0 mass% or more, and the ratio of the total number of epoxy groups in the resin composition to the total number of imidazole groups in the resin composition is 4.0 or more. [2] The resin composition according to [1], wherein the imidazole compound is a compound having a melting point of 1130°C or more or a compound exhibiting no melting point. [3] The resin composition according to [1] or [2], wherein the imidazole compound is a compound containing a hydroxymethyl group. [4] The resin composition according to any one of [1] to [3], further comprising a photopolymerization initiator having a molecular weight of 230 to 5000. [5] The resin composition according to [4], wherein the photopolymerization initiator is an oxime ester compound. [6] The resin composition is applied to a thickness of 100 μm, and irradiated with light calibrated with a 365 nm wavelength sensor at 3000 mJ / cm. ２ When a cured film was produced by irradiating the film with ultraviolet light and heating it at 120°C for 1 hour, the moisture permeability of the cured film measured by the following method was 66 g / m ２ The resin composition according to any one of [1] to [5], which is as follows: (Method for measuring moisture permeability) (i) Two sheets of the cured film are placed on an aluminum cup containing anhydrous calcium chloride, and an aluminum ring is placed on top of the aluminum cup and screwed together; (ii) The weight of the aluminum cup after screwing is measured; (iii) The aluminum cup after screwing is placed in a thermostatic chamber set to 60°C and 90% Rh for 24 hours; (iv) The weight of the aluminum cup after screwing is measured after storage in the thermostatic chamber; and (v) The moisture permeability is calculated based on the following formula: Moisture permeability = (weight of the aluminum cup after screwing in (iv) - weight of the aluminum cup after screwing in (ii)) / area of ​​the cured film.

[0009] The present invention provides the following liquid crystal sealant: [7] A liquid crystal sealant comprising the resin composition according to any one of [1] to [6] above.

[0010] The present invention provides the following liquid crystal display panel. [8] A liquid crystal display panel comprising a pair of substrates, a liquid crystal disposed between the pair of substrates, and a sealant disposed between the pair of substrates and sealing the liquid crystal, wherein the sealant has an adhesive strength of more than 1.0 N / mm as measured by the following method: (Method for measuring adhesive strength) (i) Two rectangular glass substrates, each 25 mm wide and 45 mm long, having a polyimide layer on one surface, are prepared; (ii) A precursor of the sealant is applied in the form of a cylinder with a diameter of 4 mm and a thickness of 5 μm to an area including the center of the surface on which the polyimide layer is disposed of one of the glass substrates; (iii) The two glass substrates are opposed to each other with a gap of 5 μm between them so that the area on the surface on which the polyimide layer is disposed of of the other glass substrate is in contact with the precursor and so that the two glass substrates are perpendicular to each other; (iv) Visible light containing light with a wavelength of 370 to 450 nm is irradiated onto the precursor at 3 J / cm. ２ (v) A load of 37.5 mm / min is applied to the widthwise center and lengthwise end of one of the glass substrates in the direction in which the two glass substrates are peeled off, and the stress at which peeling occurs is defined as the adhesive strength. [9] The liquid crystal display panel according to [8], wherein the sealing material has an area ratio of display unevenness occurring in 40% or less as measured by the following method. (Method of measuring display unevenness) (i) Two rectangular glass substrates each having a width of 40 mm and a length of 45 mm and having a polyimide layer on one surface are prepared. (ii) A seal pattern of the precursor of the sealant is applied to the polyimide layer of one of the glass substrates in a square line shape of 22 mm x 22 mm. (iii) Liquid crystal (product number JC-5172XX manufactured by JNC Corporation) is filled inside the seal pattern. (iv) The other glass substrate is placed on the liquid crystal under reduced pressure so that the polyimide layer of the other glass substrate is in contact with the liquid crystal, and the pressure is released to atmospheric pressure to bond them together. (v) The entire area of ​​the liquid crystal and the seal pattern is covered with an ultraviolet light mask. (vi) Ultraviolet light at 1 J / cm is irradiated onto the entire surface of the glass substrate using a high-pressure mercury lamp.２ (vii) The image of the obtained laminate is analyzed to identify the total planar area B of the area where unevenness occurs in the liquid crystal relative to the planar area A of the liquid crystal, and the ratio of the area where display unevenness occurs is calculated based on the following formula: Ratio (%) of area where display unevenness occurs = B / A * 100

[0011] According to the present invention, there are provided a resin composition which, when used as a liquid crystal sealant, can form a sealant which has high adhesion to various substrates and excellent moisture resistance, and a liquid crystal sealant and a liquid crystal display panel using the same.

[0012] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. In this specification, when a composition contains multiple substances corresponding to each component, the amount of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. In the numerical ranges described in stages in this specification, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another numerical range described in stages.

[0013] 1. Resin Composition The resin composition of the present invention may contain an epoxy resin having two or more epoxy groups in the molecule, a (meth)acrylic-modified epoxy resin having an epoxy group and a (meth)acryloyl group in the molecule, a (meth)acrylic compound having an epoxy group and a (meth)acryloyl group in the molecule, and an imidazole compound, and may also contain other components as necessary. Examples of the other components include a photopolymerization initiator, inorganic particles, organic particles, various additives, etc.

[0014] As described above, conventional resin compositions for liquid crystal sealants have problems such as low adhesive strength with substrates having hydrophobic surfaces on which alignment films or the like are formed, and low moisture resistance. In response to these problems, the present inventors conducted extensive research and found that, in many resin compositions, amine-based curing agents have traditionally been used as heat curing agents for curing epoxy resins. However, amine-based curing agents react until a primary amine becomes a tertiary amine, as shown in the following reaction formula: For example, when a primary amine reacts with one epoxy resin (epoxy group), a secondary amine is formed, and an OH group derived from the epoxy group is generated. This secondary amine then further reacts with another epoxy resin (epoxy group) to form a tertiary amine, which also generates an OH group derived from the epoxy group. In other words, when one amine reacts with multiple epoxy groups, two OH groups are generated. Furthermore, when a diamine compound is used as a curing agent, four OH groups are generated per diamine compound. Therefore, the cured product of the resin composition contains many OH groups. As a result, it is thought that the cured product will have difficulty adhering to the hydrophobic substrate. The same is true for hydrazide and triazine curing agents.

[0015] On the other hand, when an imidazole compound reacts with an epoxy resin (epoxy group), the epoxy group opens and generates an oxoanion. The oxoanion then reacts with the epoxy resin (epoxy group), causing polymerization. In other words, in the reaction between an imidazole compound and an epoxy resin, only one OH group is generated per imidazole group. This is thought to improve adhesion between the cured resin composition and a hydrophobic substrate, and further improve moisture resistance.

[0016] In addition, the present invention contains an imidazole-based compound in an amount of 4.0% by mass or more relative to the total amount of the resin composition. As described above, imidazole-based compounds are unlikely to generate OH groups when reacting with epoxy resins. Therefore, even when used in relatively large amounts, they are unlikely to impair adhesion between the cured product and the substrate, and are also unlikely to allow moisture to pass through. Furthermore, by setting the amount of imidazole-based compound to 4.0% by mass or more, the thermosetting properties of the resin composition are improved, resulting in a cured product with sufficiently high strength, etc. Furthermore, in the resin composition of the present invention, the ratio of the total number of epoxy groups in the resin composition to the total number of imidazole groups is 4.0 or more. By satisfying this ratio, the hydrophobicity of the cured product is enhanced, and effects such as improved adhesion between the cured product and the substrate and improved moisture resistance are easily achieved. Each component of the resin composition of the present invention is described in detail below.

[0017] 1-1. Epoxy Resin The epoxy resin is a resin having two or more epoxy groups in the molecule and not containing a (meth)acryloyl group in the molecule. The resin composition may contain only one type of epoxy resin, or may contain two or more types. Examples of the epoxy resin include known epoxy resins. Examples of the epoxy resin include aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc., but aromatic epoxy resins are preferred from the viewpoint of improving the moisture resistance of the resulting cured product (sealant).

[0018] Examples of aromatic epoxy resins include aromatic polyhydric glycidyl ether resins obtained by reacting epichlorohydrin with aromatic diols typified by bisphenol A, bisphenol S, bisphenol F, bisphenol AD, etc., or diols obtained by modifying these aromatic diols with ethylene glycol, propylene glycol, alkylene glycol, etc.; novolak-type polyhydric glycidyl ether resins obtained by reacting epichlorohydrin with polyphenols typified by novolak resins derived from phenol or cresol and formaldehyde, polyalkenylphenols, copolymers thereof, etc.; and glycidyl ethers of xylylene phenol resins.

[0019] Among the aromatic epoxy resins, cresol novolac epoxy resins, phenol novolac epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, triphenolmethane epoxy resins, triphenolethane epoxy resins, trisphenol epoxy resins, dicyclopentadiene epoxy resins, diphenyl ether epoxy resins, and biphenyl epoxy resins are preferred. The resin composition may contain only one of these or two or more of them.

[0020] The epoxy resin may be liquid or solid at room temperature (e.g., 25°C). A liquid resin is preferred from the viewpoint of easily adjusting the viscosity of the resin composition. On the other hand, a solid resin is preferred from the viewpoint of easily increasing the moisture resistance of the resulting cured product. The softening point of the solid epoxy resin 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.

[0021] The weight average molecular weight of the epoxy resin is preferably 300 to 10,000, more preferably 300 to 5,000. The weight average molecular weight of the epoxy resin can be measured (in terms of polystyrene) by, for example, gel permeation chromatography (GPC).

[0022] The epoxy group equivalent of the epoxy resin is not particularly limited as long as the ratio of the number of epoxy groups in the resin composition to the number of imidazole groups in the resin composition can be made 4.0 or more. In this specification, the epoxy group equivalent of the epoxy resin is the value (g / eq) obtained by dividing the molecular weight (or weight average molecular weight) of the epoxy resin by the number of epoxy groups contained in the epoxy resin.

[0023] 1-2. (Meth)acrylic-Modified Epoxy Resin The (meth)acrylic-modified epoxy resin (hereinafter also referred to as "modified epoxy resin") may be a resin having an epoxy group and a (meth)acryloyl group in the molecule. The resin composition may contain only one type of modified epoxy resin, or may contain two or more types. Examples of modified epoxy resins include resins obtained by reacting an epoxy resin with (meth)acrylic acid in the presence of a basic catalyst. In this specification, (meth)acryloyl means methacryloyl, acryloyl, or both. Furthermore, (meth)acrylic means methacrylic, acrylic, or both.

[0024] The modified epoxy resin has both photocurable and thermosetting properties due to the presence of an epoxy group and a (meth)acryloyl group in the molecule. Therefore, the modified epoxy resin has good affinity with the epoxy resin and the (meth)acrylic compound described below. Therefore, the modified epoxy resin enhances the compatibility between the epoxy resin and the (meth)acrylic compound. Furthermore, the inclusion of the modified epoxy resin in the resin composition makes it easier to suppress the dissolution of the epoxy resin in liquid crystal.

[0025] The epoxy resin to be reacted with (meth)acrylic acid may be a polyfunctional epoxy resin having two or more epoxy groups in the molecule. From the viewpoint of preventing excessive crosslinking density and a decrease in adhesiveness of the cured resin composition, a bifunctional epoxy resin is preferred. Examples of bifunctional epoxy resins include bisphenol-type epoxy resins (bisphenol A type, bisphenol F type, 2,2'-diallyl bisphenol A type, bisphenol AD ​​type, hydrogenated bisphenol type, etc.), biphenyl-type epoxy resins, and naphthalene-type epoxy resins. Among these, bisphenol-type epoxy resins of bisphenol A type and bisphenol F type are preferred from the viewpoint of improving the coatability of the resin composition. (Meth)acrylic-modified epoxy resins derived from bisphenol-type epoxy compounds have advantages such as superior coatability compared to (meth)acrylic-modified epoxy resins derived from biphenyl ether-type epoxy resins.

[0026] The modified epoxy resin contains a hydroxyl group generated by the reaction of (meth)acrylic acid with the epoxy resin, and may also contain a hydrogen-bonding functional group such as a urethane bond, an amide group, a carboxyl group, etc. If the modified epoxy resin contains a hydrogen-bonding functional group, the compatibility of the modified epoxy resin with liquid crystal decreases, and the dissolution of the modified epoxy resin in liquid crystal tends to be suppressed.

[0027] The hydrogen-bonding functional group equivalent of the modified epoxy resin is 1.0 × 10 －４ ~5 x 10 －３ mol / g is preferred, and 2.0×10 －３ ~4.5 x 10 －３ mol / g is more preferable. －４ If the equivalent of the hydrogen-bonding functional groups in the modified epoxy resin is less than 5×10 mol / g, the number of hydrogen-bonding functional groups in the modified epoxy resin is small, making it difficult to obtain the effect of inhibiting dissolution of the liquid crystal. －３ If it exceeds 1 / mol / g, the moisture resistance of the cured product of the liquid crystal sealant may decrease.

[0028] The hydrogen-bonding functional group equivalent (mol / g) in the modified epoxy resin can be calculated by dividing the number of hydrogen-bonding functional groups contained in one molecule of the modified epoxy resin by the weight-average molecular weight (Mw) of the modified epoxy resin. For example, when the only hydrogen-bonding functional groups in the modified epoxy resin are hydroxyl groups generated by the reaction of (meth)acrylic acid with the epoxy resin, the equivalent weight can be calculated by dividing the number of moles of (meth)acrylic acid reacted with the epoxy resin by the weight-average molecular weight (Mw) of the modified epoxy resin.

[0029] Here, the hydrogen-bonding functional group equivalent of the modified epoxy resin can be controlled by adjusting the number of moles of (meth)acrylic acid reacted with the raw epoxy resin, or by adjusting the amount of hydrogen-bonding functional groups possessed by the raw epoxy resin. The hydroxyl value equivalent of the modified epoxy resin is 2.0 × 10 －３ ~5 x 10 －３ mol / g is particularly preferred.

[0030] The weight average molecular weight of the modified epoxy resin is, for example, preferably 310 to 1000, more preferably 350 to 900. The weight average molecular weight Mw of the modified epoxy resin can be measured (in terms of polystyrene) by, for example, gel permeation chromatography (GPC).

[0031] The epoxy group equivalent of the modified epoxy resin is not particularly limited as long as the ratio of the number of epoxy groups in the resin composition to the number of imidazole groups in the resin composition can be made 4.0 or more. In this specification, the epoxy group equivalent of the modified epoxy resin is the value (g / eq) obtained by dividing the molecular weight (or weight average molecular weight) of the modified epoxy resin by the number of epoxy groups contained in the modified epoxy resin.

[0032] 1-3. (Meth)acrylic Compound The (meth)acrylic compound may be a resin containing one or more (meth)acryloyl groups in the molecule and not containing an epoxy group. The resin composition may contain only one type of (meth)acrylic compound, or may contain two or more types. The (meth)acrylic compound may be a monomer, an oligomer, or a polymer.

[0033] The number of (meth)acryloyl groups contained in the (meth)acrylic compound may be 1 or may be 2 or more. Examples of monofunctional (meth)acrylic compounds containing one (meth)acryloyl group in one molecule include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, isobornyl (meth)acrylic acid, dicyclopentanyl (meth)acrylic acid, and 2-hydroxyethyl (meth)acrylic acid ester.

[0034] Examples of polyfunctional (meth)acrylic compounds 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)acrylates derived from tris(2-hydroxyethyl)isocyanurate; di(meth)acrylates derived from a diol obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol; di(meth)acrylates (bisphenol A or F type epoxy(meth)acrylates) derived from a diol obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A or bisphenol F; di- or tri(meth)acrylates derived from a polyol obtained by adding 2 or 3 moles of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane; di(meth)acrylates derived from a diol obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A; tris(2-hydroxyethyl)isocyanurate; (ethyl) 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; alkyl-modified dipentaerythritol poly(meth)acrylate; caprolactone Poly(meth)acrylate of lactone-modified dipentaerythritol; hydroxypivalic acid neopentyl glycol di(meth)acrylate; caprolactone-modified hydroxypivalic acid neopentyl glycol di(meth)acrylate; ethylene oxide-modified phosphate (meth)acrylate; ethylene oxide-modified alkylated phosphate (meth)acrylate; di(meth)acrylate obtained by adding 2 moles of succinic acid or phthalic acid and hydroxypropyl (meth)acrylate to 1 mole of bisphenol A or bisphenol F;and oligo(meth)acrylates of neopentyl glycol, trimethylolpropane, and pentaerythritol; aliphatic urethane (meth)acrylates, etc. Among these, di(meth)acrylates (bisphenol A or F type epoxy (meth)acrylates) derived from diols obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A or bisphenol F are preferred.

[0035] The weight average molecular weight of the (meth)acrylic compound measured by gel permeation chromatography (GPC) is preferably 200 to 10,000, more preferably 200 to 5,000.

[0036] 1-4. Contents of Epoxy Resin, (Meth)acrylic-Modified Epoxy Resin, and (Meth)acrylic Compound The contents of the epoxy resin, (meth)acrylic-modified epoxy resin, and (meth)acrylic compound in the resin composition are preferably adjusted as follows.

[0037] The sum of the amount of the resin having an epoxy group in the resin composition, i.e., the amount of the epoxy resin, and the amount of the (meth)acrylic-modified epoxy resin calculated as described below, is preferably 15% by mass or more and 81% by mass or less, preferably 20% by mass or more and 80% by mass or less, and more preferably 30% by mass or more and 75% by mass or less, relative to the total amount of the resin composition. When the amount of the resin having an epoxy group is within this range, the moisture resistance of the cured product tends to be improved. Note that the amount of the (meth)acrylic-modified epoxy resin is calculated by multiplying the amount of the (meth)acrylic-modified epoxy resin by the proportion of epoxy terminal groups.

[0038] The sum of the amount of the resin having a (meth)acrylic group contained in the resin composition, i.e., the amount of the (meth)acrylic compound, and the amount of the (meth)acrylic-modified epoxy resin calculated as described below, is preferably 15% by mass or more and 81% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 75% by mass or less, relative to the total amount of the resin composition. When the amount of the resin having a (meth)acrylic group is within this range, the photocurability of the resin composition tends to be good. Note that the amount of the (meth)acrylic-modified epoxy resin is calculated by multiplying the amount of the (meth)acrylic-modified epoxy resin by the proportion of (meth)acrylic terminal groups.

[0039] However, if the amount of monofunctional (meth)acrylic compounds in the (meth)acrylic compounds is large, the moisture permeability of the resulting cured product tends to be high. Therefore, the total amount of monofunctional (meth)acrylic compounds relative to the total amount of the resin composition is preferably 20 mass% or less, and more preferably 10 mass% or less.

[0040] Furthermore, the amount of the (meth)acrylic-modified epoxy resin relative to the total amount of the epoxy resin, the (meth)acrylic-based compound is preferably 35% by mass or more and 68% by mass or less, and more preferably 38% by mass or more and 65% by mass or less. When the amount of the (meth)acrylic-modified epoxy resin is within this range, the adhesion between the cured product of the resin composition and a hydrophobic substrate tends to be improved.

[0041] 1-5. Imidazole-Based Compound The imidazole-based compound may be any compound that has one or more imidazole groups in the molecule and that can react with the epoxy groups contained in the epoxy resins and modified epoxy resins by heating to thermally cure these resins.

[0042] Examples of imidazole compounds include compounds having a structure represented by the following general formula: In the above general formula, R １ and R ２each independently represents a hydrogen atom; an alkyl group having 1 to 17 carbon atoms such as a methyl group, an ethyl group, or a propyl group (preferably having 1 to 4 carbon atoms); a hydroxyalkyl group having 1 to 4 carbon atoms such as a hydroxymethyl group or a hydroxyethyl group (however, the number of hydroxy groups may be 2 or more); a phenyl group; a benzyl group; 1,3,5-triazine-2,4-diamine bonded via an alkylene group having 1 to 4 carbon atoms, etc. Among the above, R １ is preferably a hydrogen atom or 1,3,5-triazine-2,4-diamine bonded via an alkylene group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom. ２ is preferably a methyl group or a phenyl group, more preferably a phenyl group.

[0043] R ３ and R ４ each independently represents a hydrogen atom; an alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, or a propyl group; or a hydroxyalkyl group having 1 to 4 carbon atoms, such as a hydroxymethyl group or a hydroxyethyl group (however, the number of hydroxy groups may be two or more). Among these, a methyl group and a hydroxymethyl group are preferred, and R ３ and R ４ When the imidazole compound contains a hydroxymethyl group, the imidazole compound is less likely to dissolve in the liquid crystal when the uncured resin composition comes into contact with the liquid crystal, and display unevenness is less likely to occur on the liquid crystal display panel.

[0044] Here, the imidazole compound may have isocyanuric acid or 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane or the like added thereto, if necessary.

[0045] The imidazole compound is preferably a compound having a melting point of 100° C. or higher, or a compound exhibiting no melting point, from the viewpoint of viscosity stability of the resin composition and the fact that it is unlikely to cause display unevenness when used in a liquid crystal sealant. When the imidazole compound has a melting point, the melting point is more preferably 130° C. or higher, even more preferably more than 150° C., and particularly preferably 180° C. or higher.

[0046] Specific examples of the imidazole-based compound include 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 6-(2-(2-methyl-1H-imidazol-1-yl)ethyl)-1,3,5-triazine-2,4-diamine, 2-heptadecylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenylimidazole. Among these, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 6-(2-(2-methyl-1H-imidazol-1-yl)ethyl)-1,3,5-triazine-2,4-diamine, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenylimidazole are preferred, and 2-phenyl-4-methyl-5-hydroxymethylimidazole and 2-phenyl-4,5-dihydroxymethylimidazole are particularly preferred.

[0047] The imidazole group equivalent of the imidazole compound is not particularly limited as long as the ratio of the number of epoxy groups in the resin composition to the number of imidazole groups in the resin composition can be made 4.0 or more. In this specification, the imidazole group equivalent of the imidazole compound is the value (g / eq) obtained by dividing the molecular weight of the imidazole compound by the number of imidazole groups contained in the imidazole compound.

[0048] The ratio of the number of epoxy groups in the resin composition to the number of imidazole groups in the resin composition may be 4.0 or more, preferably 4.5 or more, more preferably 5.0 or more, and even more preferably 6.0 or more. When this ratio is 4.0 or more, as described above, the hydrophobicity of the cured product tends to be increased. The above ratio is determined as follows. First, the content ratio (mass %) M of the imidazole-based compound in the resin composition is determined. ｉ (When multiple types of imidazole compounds are contained, the content ratio of each imidazole compound) and the imidazole group equivalent E of the imidazole compound ｉ The content ratio (mass%) of the epoxy resin in the resin composition M ｅ(When multiple types of epoxy resins are contained, the content ratio of each epoxy resin) and the epoxy equivalent E of the epoxy resin ｅ Similarly, the content (mass%) of the modified epoxy resin in the resin composition M ａ (When multiple types of modified epoxy resins are contained, the content ratio of each modified epoxy resin) and the epoxy equivalent E ａ Then, the ratio is calculated based on the following formula: ｅ / E ｅ +M ａ / E ａ ) / (M ｉ / E ｉ )

[0049] The total amount of imidazole compounds contained in the resin composition may be at least 4% by mass, preferably at least 6% by mass but not more than 70% by mass, and more preferably at least 7% by mass but not more than 65% by mass, based on the total amount of the resin composition. When the amount of imidazole compounds is within this range, the resin composition tends to have good thermosetting properties.

[0050] In the resin composition of the present invention, the imidazole compound functions as a heat curing agent. Therefore, it is preferable that the amount of known heat curing agents, such as amine curing agents, hydrazide curing agents, and triazine curing agents, is small. Specifically, the amount of heat curing agents other than the imidazole compound is preferably 20 mass% or less, more preferably 15 mass% or less, even more preferably 10 mass% or less, and even more preferably 3 mass% or less, relative to the total amount of the resin composition, and particularly preferably zero.

[0051] 1-6. Photopolymerization Initiator The resin composition may contain a photopolymerization initiator for photopolymerizing the (meth)acrylic compound and the modified epoxy compound. The photopolymerization initiator is not particularly limited as long as it is a compound that can radically polymerize the (meth)acrylic compound or the like when irradiated with light. The resin composition may contain only one type of photopolymerization initiator, or may contain two or more types. The photopolymerization initiator may be, for example, a self-cleaving photopolymerization initiator or a hydrogen-withdrawing inorganic photopolymerization initiator.

[0052] Examples of the self-cleaving photopolymerization initiator include alkylphenone compounds (e.g., benzyl dimethyl ketals such as 2,2-dimethoxy-1,2-diphenylethan-1-one (manufactured by BASF, IRGACURE 651); α-aminoalkylphenones such as 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one (manufactured by BASF, IRGACURE 907); 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF, IRGACURE 908); 184) and the like), acylphosphine oxide compounds (for example, 2,4,6-trimethylbenzoin diphenylphosphine oxide, etc.), titanocene compounds (for example, bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, etc.), acetophenone compounds (for example, 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 4-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, etc.; phenyl glyoxylate compounds (e.g., methylphenyl glyoxyester, etc.); benzoin ether compounds (e.g., benzoin, benzoin methyl ether, benzoin isopropyl ether, etc.); and oxime ester compounds (e.g., 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-(O-acetyloxime) (manufactured by BASF, IRGACURE OXE02), etc.).

[0053] Examples of the hydrogen abstraction type photopolymerization initiator include benzophenone compounds (e.g., benzophenone, o-benzoylmethylbenzoate-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-methoxybenzophenone, etc.), thioxanthone compounds (e.g., thioxanthone, 2-chlorothioxanthone (manufactured by Tokyo Chemical Industry Co., Ltd.), 1-chloro-4-propoxythioxanthone, 1-chloro-4-ethoxythioxanthone (manufactured by Lambson Limited, Speedcure CPTX), 2-isopropylxanthone (manufactured by Lambson Limited, Speedcure CPTX), ITX), 4-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone (manufactured by Lambson Limited, Speedcure DETX), 2,4-dichlorothioxanthone, etc.), anthraquinone-based compounds (for example, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 1-chloroanthraquinone, 2-hydroxyanthraquinone (manufactured by Tokyo Chemical Industry Co., Ltd., 2-hydroxyanthraquinone), 2,6-dihydroxyanthraquinone (manufactured by Tokyo Chemical Industry Co., Ltd., Anthraflavic Acid), 2-hydroxymethylanthraquinone (manufactured by Junsei Chemical Co., Ltd., 2-(hydroxymethyl)anthraquinone), etc.), and benzyl-based compounds.

[0054] The absorption wavelength of the photopolymerization initiator is not particularly limited, and for example, a photopolymerization initiator that absorbs light with a wavelength of 360 nm or more is preferred. Among these, it is more preferred that the photopolymerization initiator absorbs light in the visible light region, and a photopolymerization initiator that absorbs light with a wavelength of 360 to 430 nm is particularly preferred. In this specification, the "visible light region" refers to a wavelength range of 360 to 780 nm.

[0055] Examples of photopolymerization initiators that absorb light with a wavelength of 360 nm or more include alkylphenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, thioxanthone compounds, and anthraquinone compounds, and preferably oxime ester compounds.

[0056] The structure of the photopolymerization initiator can be identified by combining high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC / MS) with NMR measurement or IR measurement.

[0057] The molecular weight of the photopolymerization initiator is preferably, for example, 200 or more and 5000 or less. If the molecular weight is 200 or more, when the resin composition is used as a liquid crystal sealant, the photopolymerization initiator is less likely to dissolve into the liquid crystal. On the other hand, if the molecular weight is 5000 or less, the compatibility with the above-mentioned components is increased, and the photocurability of the resin composition is likely to be good. The molecular weight of the photopolymerization initiator is more preferably 230 or more and 5000 or less, even more preferably 230 or more and 3000 or less, and particularly preferably 230 or more and 1500 or less.

[0058] The molecular weight of the photopolymerization initiator 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).

[0059] Specifically, a sample solution is prepared by dissolving the photopolymerization initiator (B) in THF (tetrahydrofuran), and high-performance liquid chromatography (HPLC) measurement is performed. The area percentage of the detected peaks (the ratio of the area of ​​each peak to the total area of ​​all peaks) is then calculated to confirm the presence or absence of a main peak. The main peak refers to the peak with the greatest intensity (the peak with the highest height) among all peaks detected at a detection wavelength characteristic of each compound (e.g., 400 nm for thioxanthone 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).

[0060] The total amount of photopolymerization initiator contained in the resin composition is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and even more preferably 0.1% by mass or more and 3% by mass or less, relative to the total amount of the resin composition. When the amount of photopolymerization initiator is within this range, the photocurability of the resin composition tends to be good. Furthermore, when the amount is 10% by mass or less, when the resin composition is used as a liquid crystal sealant, it is less likely to dissolve into the liquid crystal, making it easier to suppress liquid crystal contamination.

[0061] 1-7. Other Components The resin composition may contain other components in addition to those described above, as long as the purpose and effects of the present invention are not impaired. Examples of other components include inorganic particles, organic particles, various additives, etc.

[0062] Examples of inorganic particles include inorganic fillers such as calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, aluminum oxide (alumina), zinc oxide, silicon dioxide (silica), potassium titanate, kaolin, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, and silicon nitride, with silicon dioxide and talc being preferred. Among these, silicon dioxide (silica) and talc are preferred. The resin composition may contain only one type of inorganic particle, or two or more types.

[0063] The shape of the inorganic particles is not particularly limited, and may be any of regular shapes such as spherical, plate-like, and needle-like, or irregular shapes. The average primary particle diameter of the inorganic particles is preferably 1.5 μm or less, and the specific surface area thereof is preferably 0.5 m ２ / g to 20m ２ The average primary particle size of the inorganic particles can be measured by the laser diffraction method described in JIS Z8825-1, and the specific surface area can be measured by the BET method described in JIS Z8830.

[0064] The amount of inorganic particles contained in the resin composition is preferably 1 to 30 mass %, more preferably 3 to 25 mass %, and even more preferably 5 to 20 mass %, based on the total amount of the resin composition. When the amount of inorganic particles is within this range, the viscosity and other properties of the resin composition tend to fall within the desired range.

[0065] On the other hand, examples of organic particles include silicone particles, acrylic particles, styrene particles such as styrene-divinylbenzene copolymer particles, and polyolefin particles. The liquid crystal sealant may contain only one type of organic particle, or may contain two or more types. The average primary particle size of the organic particles is preferably 0.05 to 13 μm, more preferably 0.1 to 10 μm, and even more preferably 0.1 to 8 μm.

[0066] The shape of the organic particles is not particularly limited, but is preferably spherical, and more preferably true spherical. Spherical means that the ratio of the minimum diameter (b) of each particle to the maximum diameter (a) of the particle, b / a, is 0.9 to 1.0. The average primary particle size of the organic particles can be measured by a microscopic method, specifically, image analysis using an electron microscope. The organic particles preferably have a smooth surface. A smooth surface reduces the specific surface area, increasing the amount of organic particles that can be added to a resin composition.

[0067] The content of the organic particles in the resin composition is preferably 0.1 to 30 mass %, more preferably 0.3 to 20 mass %, and even more preferably 0.3 to 15 mass %, based on the total amount of the resin composition. When the amount of the organic particles is within this range, the elastic modulus of the resin composition after photocuring tends to fall within the desired range.

[0068] If necessary, the resin composition may further contain a coupling agent such as a silane coupling agent, an ion trapping agent, an ion exchange agent, a leveling agent, a pigment, a dye, a plasticizer, an antifoaming agent, etc. Furthermore, the resin composition may further contain a spacer or the like for adjusting the gap of the liquid crystal display panel.

[0069] 1-8. Uses and Properties of Resin Composition The uses of the resin composition are not limited, but as mentioned above, the resin composition is very suitable as a liquid crystal sealant for sealing liquid crystals in liquid crystal display panels. It is particularly suitable as a liquid crystal sealant for display panels having narrow frame widths. Preferred physical properties for use as a resin liquid crystal sealant are shown below.

[0070] The viscosity of the liquid crystal sealant measured at 25°C and 2.5 rpm using an E-type viscometer is preferably 200 to 450 Pa·s, more preferably 300 to 400 Pa·s. When the viscosity is in the above range, the liquid crystal sealant can be easily applied using a dispenser.

[0071] 2. Liquid Crystal Display Panel and Manufacturing Method Thereof The liquid crystal display panel of the present invention may include a pair of substrates, a liquid crystal disposed between the pair of substrates, and a sealant disposed between the pair of substrates and sealing the liquid crystal. The sealant has an adhesive strength of more than 1.0 N / mm as measured by the following method. Liquid Crystal Display Panel. (Method for Measuring Adhesion Strength) (i) Two rectangular glass substrates, each 25 mm wide and 45 mm long, having a polyimide layer on one side are prepared. (ii) A sealant precursor is applied to one of the glass substrates in a cylindrical shape with a diameter of 4 mm and a thickness of 5 μm on a region including the center of the surface on which the polyimide layer is disposed. (iii) The two glass substrates are opposed to each other with a gap of 5 μm between them so that the region including the center of the surface on which the polyimide layer is disposed of on the other glass substrate is in contact with the top surface of the cylindrical precursor and so that the two glass substrates are perpendicular to each other. (iv) Visible light containing light with a wavelength of 370 to 450 nm is irradiated onto the precursor at 3 J / cm. ２ (v) One of the two glass substrates is fixed. A load of 37.5 mm / min is applied to the widthwise center and lengthwise end of the other glass substrate in the peeling direction. The stress at which peeling occurs is taken as the adhesive strength.

[0072] The adhesive strength is preferably 1.1 N / mm or more, and more preferably 1.2 N / mm or more. When the adhesive strength exceeds 1.0 N / mm, for example, even when the encapsulant is formed on an alignment film, a very high adhesive strength is exhibited. Therefore, it can be said that a liquid crystal display panel having such an encapsulant can realize a narrow frame. The encapsulant having the above adhesive strength can be produced, for example, from the resin composition.

[0073] Furthermore, the above-mentioned encapsulant preferably has an area where display unevenness occurs, as measured by the following method, of 40% or less. Using an encapsulant that is less likely to cause display unevenness in this way allows for the production of a higher-quality display panel. This encapsulant can be produced using the above-mentioned resin composition (particularly a resin composition using a compound having a hydroxymethyl group as an imidazole-based compound). (Display Unevenness Measurement Method) (i) Two rectangular glass substrates, each 40 mm wide and 45 mm long, having a polyimide layer on one side are prepared. (ii) A seal pattern of the encapsulant precursor is applied to the polyimide layer of one of the glass substrates in a 22 mm x 22 mm square line pattern. (iii) Liquid crystal (product number JC-5172XX, manufactured by JNC Corporation) is filled inside the seal pattern. (iv) The other glass substrate is placed on top of the liquid crystal under reduced pressure so that the polyimide layer of the other glass substrate is in contact with the liquid crystal, and the pressure is released to atmospheric pressure to bond them together. (v) Covering the entire area of ​​the liquid crystal and the seal pattern with an ultraviolet light mask. (vi) Irradiating the entire surface of the glass substrate with ultraviolet light at 1 J / cm using a high-pressure mercury lamp. ２ (vii) The image of the obtained laminate is subjected to image analysis (for example, analysis using image processing software ImageJ), and the total planar area B of the area where unevenness occurs in the liquid crystal relative to the planar area A of the liquid crystal is identified, and the ratio of the area where display unevenness occurs is calculated based on the following formula: Ratio (%) of area where display unevenness occurs = B / A * 100

[0074] The pair of substrates in a liquid crystal display panel is a display substrate and an opposing substrate, both of which are typically transparent substrates. The transparent substrates may be made of an inorganic material such as glass, or a plastic such as polycarbonate, polyethylene terephthalate, polyethersulfone, or PMMA.

[0075] A matrix-shaped TFT, a color filter, a black matrix, etc. may be arranged on the surface of the display substrate or the counter substrate. An alignment film may further be arranged on the surface of the display substrate or the counter substrate. The alignment film contains a known organic alignment agent or an inorganic alignment agent.

[0076] The liquid crystal may be the same as that used for known liquid crystal display panels.

[0077] The method for manufacturing the liquid crystal display panel is not particularly limited. Generally, there are two methods for manufacturing liquid crystal display panels: a liquid crystal dropping method and a liquid crystal injection method. The liquid crystal display panel is preferably manufactured by the liquid crystal dropping method. Hereinafter, a method for manufacturing a liquid crystal display panel using a liquid crystal sealant containing the resin composition will be described.

[0078] The manufacturing method for a liquid crystal display panel using the liquid crystal dropping method includes the steps of: 1) applying a liquid crystal sealant in a pattern (frame shape) onto the alignment film of one of a pair of substrates, each having an alignment film, to form a seal pattern; 2) dropping liquid crystal onto one of the substrates in an area surrounded by the seal pattern, or onto the other substrate, while the seal pattern is in an uncured state; 3) overlapping the one substrate and the other substrate with the seal pattern and liquid crystal interposed between them; and 4) curing the seal pattern.

[0079] In step 1), the liquid crystal sealant is applied to the desired shape. There are no particular restrictions on the application method, and a general method can be used. The width of the seal pattern to be formed is not particularly limited, but the liquid crystal sealant described above has high adhesive strength to the substrate. Therefore, the width of the sealant can be set to approximately 0.3 mm to 0.6 mm.

[0080] In step 2), the seal pattern being in an uncured state means that the curing reaction of the liquid crystal sealant has not progressed to the gel point. Therefore, in step 2), the seal pattern may be semi-cured by irradiating it with light or heating in order to suppress dissolution of the liquid crystal sealant into the liquid crystal. One substrate and the other substrate are a display substrate or an opposing substrate, respectively. Furthermore, when liquid crystal is dropped onto the other substrate in step 2), the liquid crystal is dropped so that it is contained within the seal pattern when the two substrates are superimposed in step 3).

[0081] In step 4), curing by light irradiation may be followed by curing by heating. By curing by light irradiation, the liquid crystal sealant can be cured in a short time, thereby suppressing dissolution into the liquid crystal. By combining curing by light irradiation and curing by heating, damage to the liquid crystal layer caused by light can be reduced compared to curing by light irradiation alone.

[0082] The light to be irradiated is selected appropriately depending on the type of photopolymerization initiator in the liquid crystal sealant (resin composition) described above, but light in the visible light region, for example, light with a wavelength of 370 to 450 nm, is preferred. This is because light with the above wavelengths causes relatively little damage to the liquid crystal material and drive electrodes. For light irradiation, known light sources that emit ultraviolet 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.

[0083] The light irradiation energy may be sufficient as long as it is capable of reacting with the (meth)acryloyl group in the (meth)acrylic compound or the modified epoxy resin. The photo-curing time varies depending on the composition of the liquid crystal sealant, but is, for example, about 10 minutes.

[0084] The heat curing temperature varies depending on the type of imidazole compound, but is, for example, 120° C., and the heat curing time is about 2 hours.

[0085] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0086] 1. Preparation of Materials The following materials were used in the Examples and Comparative Examples.

[0087] (A) Epoxy Resin: YL983U (manufactured by Mitsubishi Chemical Corporation, bisphenol F type bifunctional epoxy resin (liquid), epoxy group equivalent: 170 g / eq); 1004AF (manufactured by Japan Epoxy Resins Co., Ltd., bisphenol A type bifunctional epoxy resin (solid), epoxy group equivalent: 925 g / eq)

[0088] (B) (Meth)acrylic-modified epoxy resin: Modified epoxy resin (B-1) prepared in Synthesis Example 1 below

[0089] Synthesis Example 1 160 g of liquid bisphenol F epoxy resin (Epotohto YDF-8170C, manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 160 g / eq), 0.1 g of a polymerization inhibitor (p-methoxyphenol), 0.2 g of a catalyst (triethanolamine), and 43.0 g of methacrylic acid were charged into a flask. Dry air was then introduced, and the mixture was refluxed at 90°C under stirring for 5 hours to react. The resulting compound was washed 20 times with ultrapure water to obtain a methacrylic acid partially modified bisphenol F epoxy resin (curable compound (B-1)).

[0090] (C) (Meth)acrylic Compounds (Meth)acrylic Compound (C-1) prepared in Synthesis Example 2 below (Meth)acrylic Compound (C-2) prepared in Synthesis Example 3 below (Meth)acrylic Compound (C-3) prepared in Synthesis Example 4 below

[0091] Synthesis Example 2 173 g of liquid bisphenol A epoxy resin (Epotohto YD-8125, manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 173 g / eq), 0.1 g of a polymerization inhibitor (p-methoxyphenol), 0.2 g of a catalyst (triethanolamine), and 75.9 g of acrylic acid were placed in a flask, and dry air was introduced into the mixture, followed by a reaction for 5 hours with stirring under reflux at 90°C. The resulting compound was washed 20 times with ultrapure water to obtain a 95% acrylic acid partially modified bisphenol A epoxy resin ((meth)acrylic compound (C-1)).

[0092] Synthesis Example 3: 116 g of 2-hydroxyethyl acrylate, 0.1 g of a polymerization inhibitor (p-methoxyphenol), and 100 g of succinic anhydride were charged into a flask. Dry air was then introduced into the mixture, and the mixture was stirred under reflux at 90°C for 5 hours to react. Subsequently, 170 g of bisphenol A diglycidyl ether was added, and the mixture was similarly stirred under reflux at 90°C for 5 hours to react. The resulting compound was washed 20 times with ultrapure water to obtain (meth)acrylic compound (C-2).

[0093] Synthesis Example 4: 160 g of liquid bisphenol F epoxy resin (Epotohto YDF-8170C, manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 160 g / eq), 0.1 g of a polymerization inhibitor (p-methoxyphenol), 0.2 g of a catalyst (triethanolamine), and 81.7 g of methacrylic acid were placed in a flask, and dry air was introduced into the mixture, which was then refluxed at 90°C with stirring for 5 hours to cause a reaction. The resulting compound was washed 20 times with ultrapure water to obtain a 95% methacrylic acid partially modified bisphenol F epoxy resin ((meth)acrylic compound (C-3)).

[0094] (D) Imidazole Compounds 2MAOK (manufactured by Shikoku Chemical Industry Co., Ltd., 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid addition salt, imidazole equivalent: 384.4 g / eq, melting point of imidazole moiety: 253°C) TIC-188 (manufactured by Nippon Soda Co., Ltd., 2-phenyl-4-methyl-5-hydroxymethylimidazole 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane adduct, imidazole equivalent: 456.2 g / eq, melting point of imidazole moiety: 193°C) C17Z (manufactured by Shikoku Chemical Industry Co., Ltd., 2-heptadecylimidazole, imidazole equivalent: 306.5 g / eq, melting point: 89°C) 2PHZ-PW (manufactured by Shikoku Chemicals Corporation, 2-phenyl-4,5-dihydroxymethylimidazole, imidazole equivalent: 204.2 g / eq, melting point: none (decomposition temperature 230°C)) 2P4MHZ-PW (manufactured by Shikoku Chemicals Corporation, 2-phenyl-4-methyl-5-hydroxymethylimidazole, imidazole equivalent: 188.2 g / eq, melting point: 193°C) 2PZ-PW (manufactured by Shikoku Chemicals Corporation, 2-phenylimidazole, imidazole equivalent: 144.2 g / eq, melting point: 142°C)

[0095] (D') Other heat curing agents: MAVT (manufactured by Shikoku Chemicals Corporation, 2-(4,6-diamino-1,3,5-triazin-2-yl)ethyl methacrylate); EH5057P (manufactured by ADEKA Corporation, modified alicyclic polyamine);

[0096] (E) Photopolymerization initiator OXE01 (manufactured by BASF Japan)

[0097] (F) Others: KBM-403 (Shin-Etsu Silicone Co., Ltd., silane coupling agent), Silica a (Admatechs Co., Ltd., SO-C1), F351 (Ganz Chemical Co., Ltd., alkyl acrylate / alkyl methacrylate copolymer).

[0098] 2. Preparation of Resin Compositions (Examples 1 to 11 and Comparative Examples 1 to 4) An epoxy resin, a (meth)acrylic-modified epoxy resin, a (meth)acrylic compound, an imidazole compound or other heat curing agent, a photopolymerization initiator, and other components were mixed in the mass ratios shown in Table 1. Then, the mixture was thoroughly mixed using a triple roll mill to obtain a uniform composition, thereby obtaining each resin composition.

[0099] 3. Evaluation The adhesive strength and display unevenness of the cured products (sealants) of the obtained resin compositions were evaluated by the following methods. The resin compositions were also evaluated for viscosity, thixotropy index (TI), and viscosity stability after storage at 23°C for 7 days. Furthermore, the glass transition temperature (Tg) and storage modulus (E') of the cured products of the resin compositions were evaluated. Each method is described below, and the results are shown in Table 1.

[0100] (1) Adhesion Strength Sealing materials were prepared from the resin compositions and their adhesion strength was measured according to the following procedure. (i) Two rectangular glass substrates, each 25 mm wide and 45 mm long, having a polyimide layer on one side were prepared. (ii) The resin composition was applied to one of the glass substrates in a cylindrical shape with a diameter of 4 mm and a thickness of 5 μm using a dispenser in an area including the center of the surface on which the polyimide layer was disposed. (iii) The other glass substrate was placed so that the area including the center of the surface on which the polyimide layer was disposed was in contact with the top surface of the (cylindrical) resin composition. At this time, the two glass substrates were opposed to each other with a gap of 5 μm between them so that they were perpendicular to each other. (iv) Visible light including light with a wavelength of 370 to 450 nm was irradiated to the resin composition through the glass substrate at 3 J / cm. ２ The resin composition was then cured by heating at 120°C for 60 minutes. (v) A load of 37.5 mm / min was applied to the obtained laminate at the widthwise center and lengthwise end of one of the glass substrates in the direction in which the two glass substrates were peeled off. The stress at which peeling occurred was defined as the adhesive strength.

[0101] (2) Display Unevenness A sealant (display panel) was prepared from the resin composition using the following procedure, and the area of ​​the region where display unevenness occurred was identified. (i) Two rectangular glass substrates, each 40 mm wide and 45 mm long, having a polyimide layer on one side were prepared. (ii) A seal pattern of the sealant precursor was applied to the polyimide layer of one of the glass substrates in a 22 mm x 22 mm square line pattern. (iii) Liquid crystal (product number JC-5172XX, manufactured by JNC Corporation) was filled inside the seal pattern. (iv) The other glass substrate was placed on the liquid crystal under reduced pressure so that the polyimide layer of the other glass substrate was in contact with the liquid crystal, and the two were then bonded together after being released to atmospheric pressure. (v) The entire area of ​​the liquid crystal and the seal pattern was covered with an ultraviolet light mask. (vi) The entire surface of the glass substrate was irradiated with ultraviolet light at 1 J / cm using a high-pressure mercury lamp. ２ (vii) The image of the obtained laminate was analyzed using image processing software ImageJ, and the total planar area B of the area where the liquid crystal had unevenness relative to the planar area A of the liquid crystal was determined, and the ratio of the area where the display unevenness occurred was calculated based on the following formula: Ratio (%) of the area where the display unevenness occurred = B / A * 100

[0102] The display unevenness was evaluated according to the following criteria: ◯: The proportion of the area where display unevenness occurred was 20% or less △: The proportion of the area where display unevenness occurred was more than 20% and 40% or less ×: The proportion of the area where display unevenness occurred was more than 40% If it was △ or better, it was judged to be practical and good.

[0103] (3) Viscosity Stability of Resin Composition The resin composition was stored at 23°C for 7 days, and the ratio of the viscosities at 25°C and 2.5 rpm before and after storage (viscosity after storage / viscosity before storage) was evaluated as viscosity stability. The evaluation was performed according to the following criteria: ◯: Viscosity after storage / viscosity before storage is 1.2 or less △: Viscosity after storage / viscosity before storage is greater than 1.2 and less than 1.4 ×: Viscosity after storage / viscosity before storage is greater than 1.4 or solidification occurred If the resin composition was △ or better, it was judged to be practical and good.

[0104] (4) Moisture Resistance of Cured Product The obtained resin composition was applied to a release paper with an applicator to a thickness of 100 μm. The resin composition was placed in a container for nitrogen substitution and purged with nitrogen for 5 minutes. After that, a 3000 mJ / cm ２ The film was then irradiated with light (calibrated with a 365 nm wavelength sensor) and heated at 120°C for 1 hour to produce a cured film. (i) Two sheets of cured film were placed on an aluminum cup containing anhydrous calcium chloride as a moisture absorbent, and an aluminum ring was then placed on top and screwed. (ii) The initial weight of the entire aluminum cup (aluminum cup after screwing) was measured. (iii) The screwed aluminum cup was placed in a thermostatic chamber set to 60°C and 90% RH and stored for 24 hours. (iv) After 24 hours of storage in the thermostatic chamber, the screwed aluminum cup was removed and its weight was measured. (v) The resulting weight was used to calculate the moisture permeability based on the following formula: Moisture permeability = (weight after test - weight before test) / film area. Note that the weight after test refers to the weight of the aluminum cup after screwing after storage in the thermostatic chamber. The weight before test refers to the weight of the aluminum cup after screwing before storage in the thermostatic chamber. Evaluation was then performed based on the following criteria. ◎: Moisture permeability is 50 g / m ２ Below ◯: Moisture permeability is 50g / m ２ Super 60g / m ２ Below △: Moisture permeability is 60 g / m ２ Super 70g / m ２ Less than ×: Moisture permeability is 70 g / m ２ If it was rated as Super △ or better, it was judged to be practical and good.

[0105]

[0106] As shown in Table 1 above, when the resin composition contained an epoxy resin having two or more epoxy groups in the molecule, a (meth)acrylic-modified epoxy resin, a (meth)acrylic compound, and an imidazole-based compound, and the amount of the imidazole-based compound was 4.0 mass% or more, and the ratio of the total number of epoxy groups in the resin composition to the total number of imidazole groups in the resin composition (total number of epoxy groups / total number of imidazole groups) was 4.0 or more, the adhesive strength between the resulting cured product (encapsulant) and the polyimide layer was sufficiently high, and the moisture resistance evaluation was also favorable (Examples 1 to 11).

[0107] In contrast, when the imidazole compound was not included or its amount was less than 4.0 mass%, the adhesive strength between the cured product and the polyimide layer was low (Comparative Examples 1, 2, and 4). In particular, when an amine-based curing agent, a triazine-based curing agent, or a hydrazide-based curing agent was used, OH groups were likely to be generated during curing, which was thought to inhibit affinity with the polyimide layer.

[0108] Furthermore, when the ratio of the total number of epoxy groups to the total number of imidazole groups was small, the viscosity stability was low and a display panel could not be produced (Comparative Example 3).

[0109] This application claims priority from Japanese Patent Application No. 2024-114726, filed July 18, 2024, the entire contents of which are incorporated herein by reference.

[0110] The resin composition of the present invention provides a cured product that has high adhesion to various substrates and excellent moisture resistance, and is therefore suitable for use as a liquid crystal sealant in the production of liquid crystal display panels.

Claims

1. A resin composition comprising: an epoxy resin having two or more epoxy groups in the molecule (excluding resins having (meth)acryloyl groups in the molecule); a (meth)acrylic-modified epoxy resin having an epoxy group and a (meth)acryloyl group in the molecule; a (meth)acrylic compound having one or more (meth)acryloyl groups in the molecule (excluding resins having epoxy groups in the molecule); and an imidazole compound, wherein the amount of the imidazole compound is 4.0 mass% or more; and the ratio of the total number of epoxy groups in the resin composition to the total number of imidazole groups in the resin composition is 4.0 or more.

2. The resin composition according to claim 1, wherein the imidazole compound is a compound having a melting point of 130°C or higher, or a compound having no melting point.

3. The resin composition according to claim 1, wherein the imidazole compound is a compound containing a hydroxymethyl group.

4. The resin composition according to claim 1, further comprising a photopolymerization initiator having a molecular weight of 230 or more and 5,000 or less.

5. The resin composition according to claim 4, wherein the photopolymerization initiator is an oxime ester compound.

6. Apply a coating to a thickness of 100 μm and expose to 3000 mJ / cm of light calibrated with a 365 nm wavelength sensor. ２ When a cured film was produced by irradiating the film with ultraviolet light and heating it at 120°C for 1 hour, the moisture permeability of the cured film measured by the following method was 66 g / m ２ The resin composition according to claim 1, wherein the moisture permeation rate is: (Method for measuring moisture permeation rate) (i) Two sheets of the cured film are placed on an aluminum cup containing anhydrous calcium chloride, and an aluminum ring is placed on top of the aluminum cup and screwed together (ii) The weight of the aluminum cup after screwing is measured (iii) The aluminum cup after screwing is stored in a thermostatic chamber set to 60°C and 90% Rh for 24 hours (iv) The weight of the aluminum cup after screwing after storage in the thermostatic chamber is measured (v) The moisture permeation rate is calculated based on the following formula: Moisture permeation rate = (Weight of the aluminum cup after screwing after storage in the thermostatic chamber - Weight of the aluminum cup after screwing before storage in the thermostatic chamber) / Area of ​​the cured film 7. A liquid crystal sealant comprising the resin composition according to any one of claims 1 to 6.

8. A liquid crystal display panel comprising a pair of substrates, a liquid crystal disposed between the pair of substrates, and a sealant disposed between the pair of substrates and sealing the liquid crystal, wherein the sealant has an adhesive strength of more than 1.0 N / mm as measured by the following method: (Method for measuring adhesive strength) (i) Two rectangular glass substrates, each 25 mm wide and 45 mm long, having a polyimide layer on one surface, are prepared; (ii) A precursor of the sealant is applied in the form of a cylinder with a diameter of 4 mm and a thickness of 5 μm to an area including the center of the surface on which the polyimide layer is disposed of one of the glass substrates; (iii) The two glass substrates are opposed to each other with a gap of 5 μm between them so that the area including the center of the surface on which the polyimide layer is disposed of of the other glass substrate is in contact with the precursor and so that the two glass substrates are perpendicular to each other; (iv) Visible light containing light with a wavelength of 370 to 450 nm is irradiated onto the precursor at 3 J / cm. ２ (v) A load of 37.5 mm / min is applied to the widthwise center and lengthwise end of one of the glass substrates in the direction in which the two glass substrates are to be peeled off, and the stress at which peeling occurs is defined as the adhesive strength.

9. The liquid crystal display panel according to claim 8, wherein the sealing material has an area ratio where display unevenness occurs of 40% or less as measured by the following method. (Method of measuring display unevenness) (i) Two rectangular glass substrates each having a width of 40 mm and a length of 45 mm and having a polyimide layer on one surface are prepared. (ii) A seal pattern of the precursor of the sealant is applied to the polyimide layer of one of the glass substrates in a square line shape of 22 mm x 22 mm. (iii) Liquid crystal (product number JC-5172XX manufactured by JNC Corporation) is filled inside the seal pattern. (iv) The other glass substrate is placed on the liquid crystal under reduced pressure so that the polyimide layer of the other glass substrate is in contact with the liquid crystal, and the pressure is released to atmospheric pressure to bond them together. (v) The entire area of ​​the liquid crystal and the seal pattern is covered with an ultraviolet light mask. (vi) Ultraviolet light at 1 J / cm is irradiated onto the entire surface of the glass substrate using a high-pressure mercury lamp. ２ (vii) The image of the obtained laminate is analyzed to identify the total planar area B of the area where unevenness occurs in the liquid crystal relative to the planar area A of the liquid crystal, and the ratio of the area where display unevenness occurs is calculated based on the following formula: Ratio (%) of area where display unevenness occurs = B / A * 100

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