TW202440694A - Liquid crystal sealant, liquid crystal display panel using the same, and method for manufacturing the same - Google Patents

Abstract

The subject of the present invention is to provide a liquid crystal sealant capable of producing a sealant having strong adhesive strength and low moisture permeability. The liquid crystal sealant for solving the above-mentioned subject comprises a curable compound and a curing agent, wherein the curable compound comprises a cyclopolymerizable compound represented by a specific chemical formula.

Description

Liquid crystal sealant, liquid crystal display panel using the same, and method for manufacturing the same

The present invention relates to a liquid crystal sealant, a liquid crystal display panel using the same, and a manufacturing method thereof.

A liquid crystal display panel generally has a pair of substrates, a frame-shaped sealing material disposed between the substrates, and a liquid crystal material sealed in a region surrounded by the sealing material. Such a liquid crystal display panel is manufactured by a liquid crystal dropping process.

In the liquid crystal drop process, first, a liquid crystal sealant is applied to one of a pair of substrates by a dispensing method to form a rectangular frame-shaped seal pattern. Then, before the liquid crystal sealant is cured, a liquid crystal material is dropped into the frame-shaped seal pattern or the corresponding area of the other substrate. Then, the substrates are stacked on top of each other under vacuum, and the frame-shaped seal pattern is irradiated with light such as ultraviolet rays for temporary curing. Afterwards, it is heated for formal curing, thereby manufacturing a liquid crystal display panel.

In recent years, as the bezels of liquid crystal display panels have become narrower, the line width of sealants has also been required to be narrower. Therefore, sealants are required to have better adhesion and moisture resistance to the substrate than before, even if the width is narrower, that is, to have a high balance between adhesion strength and low moisture permeability.

As a method for improving the low moisture permeability of a sealing material, a method of mixing an inorganic filler such as talc or alumina is known. For example, Patent Document 1 proposes a sealant for a liquid crystal display element comprising a curable resin, a radical polymerization initiator or a thermosetting agent, and alumina. In addition, Patent Document 2 proposes a sealant for a liquid crystal display element comprising a curable resin, a radical polymerization initiator or a thermosetting agent, and alumina or talc having an aspect ratio of 2 or more. [Prior Art Document] [Patent Document]

[Patent document 1] Japanese Patent Publication No. 2016-218447 [Patent document 2] Japanese Patent Publication No. 2013-214056

[The problem that the invention wants to solve]

However, in the method of mixing an inorganic filler, the obtained sealant has good low moisture permeability, but its flexibility is impaired, so there is a problem that the adhesive strength is easily reduced. As such, the adhesive strength and low moisture permeability are usually in a trade-off relationship, and it is difficult to take both into account in the existing liquid crystal sealants.

The present invention is made in view of the above-mentioned problem, and its purpose is to provide a liquid crystal sealant capable of producing a sealant with strong adhesive strength and low moisture permeability, as well as a liquid crystal display panel using the same and a method for manufacturing the same. [Means for solving the problem]

The present invention provides a liquid crystal sealant, comprising a curable compound and a curing agent, wherein the curable compound comprises a cyclopolymerizable compound represented by the following general formula (1). (In the general formula (1), ^R1 represents a hydrogen atom or a alkyl group having 1 to 30 carbon atoms, ^R2 and ^R3 each independently represent a alkyl group having 1 to 4 carbon atoms, and X represents a single bond, -O-, -S-, or ^NR4 ( ^R4 is a hydrogen atom or a alkyl group having 1 to 4 carbon atoms))

The present invention further provides a liquid crystal display panel, which has: a pair of substrates; a liquid crystal layer sandwiched between the pair of substrates; and a frame-shaped sealing material arranged between the pair of substrates and used to seal the liquid crystal layer, wherein the sealing material is a cured product of the liquid crystal sealant described above.

The present invention further provides a method for manufacturing a liquid crystal display panel, which comprises the following steps: preparing a pair of substrates; applying the above-described liquid crystal sealant on one of the substrates to form a frame-shaped seal pattern; applying a dummy sealant on the outer side of the frame-shaped seal pattern to form a dummy seal pattern; dripping a liquid crystal material onto the inner side of the frame-shaped seal pattern and/or onto another substrate when the frame-shaped seal pattern and the dummy seal pattern are not hardened; overlapping the pair of substrates via the liquid crystal material in a reduced pressure environment; and hardening the frame-shaped seal pattern and the dummy seal pattern. [Effects of the invention]

The liquid crystal sealant of the present invention can produce a sealant having strong adhesive strength and low moisture permeability.

In this specification, a numerical range expressed using "to" means a range including the numerical values described before and after "to" as the lower limit and the upper limit.

1. Liquid crystal sealant The liquid crystal sealant of the present invention only needs to include a curable resin and a curing agent for curing the curable resin, and may further include a filler or a silane coupling agent, etc., as needed.

As described above, it is difficult to achieve both high adhesive strength and low moisture permeability in the existing liquid crystal sealant after curing. In contrast, according to the diligent research of the inventors and others, it is clear that high adhesive strength and low moisture permeability can be achieved by including a cyclic polymerizable compound with a specific structure in the liquid crystal sealant. The structure of the cyclic polymerizable compound will be described in detail later. When the cyclic polymerizable compound is polymerized, a structure is formed in which multiple alicyclic structures are connected by ethylene chains. According to this polymer, the rigid alicyclic structure can inhibit the intrusion of moisture into the sealant. On the other hand, in the polymer, appropriate flexibility is exerted by the ethylene chain. Therefore, when an external force is applied to the liquid crystal display panel, the sealant can follow the substrate and deform, and the bonding strength between the substrate and the sealant becomes very high. Below, each component contained in the liquid crystal sealant of the present invention is described in detail.

1-1. Curable compound In this specification, the so-called curable compound refers to a compound that polymerizes and cures by energy such as heat or light. The curable compound only needs to contain at least the following cyclic polymerizable compound, and preferably further contains the cyclic polymerizable compound and the epoxy compound or (meth) acrylic compound, (meth) acrylic modified epoxy compound, etc. described later.

(1) Cyclic polymerizable compound As described above, the curable compound includes a cyclic polymerizable compound having a structure represented by the following general formula (1). The curable compound may include only one type of the cyclic polymerizable compound, or may include two or more types. Furthermore, the cyclic polymerizable compound is converted into a polymer having a repeating unit represented by the following general formula (2) by polymerization. [Chemistry 2] In the general formula (1) and the general formula (2), ^R1 represents a hydrogen atom or a alkyl group having 1 to 30 carbon atoms. The alkyl group preferably has 1 to 4 carbon atoms.

Specific examples of the group represented by ^R1 include: a hydrogen atom; a chain saturated alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, a sec-pentyl group, a t-pentyl group, an n-hexyl group, a sec-hexyl group, an n-heptyl group, an n-octyl group, a sec-octyl group, a t-octyl group, a 2-ethylhexyl group, a decyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecanyl group, an octadecyl group, a nonadecanyl group, an eicosyl group, a hexadecyl group, a triacontanyl group, etc.; an alkoxy-substituted chain saturated alkyl group in which a part of the hydrogen atoms of a chain saturated alkyl group such as a methoxyethyl group, a methoxyethoxyethyl group, a methoxyethoxyethoxyethyl group, a 3-methoxybutyl group, an ethoxyethyl group, an ethoxyethoxyethyl group, a phenoxyethyl group, a phenoxyethoxyethyl group, etc. are substituted with an alkoxy group; A hydroxy-substituted chain saturated alkyl group obtained by replacing a part of the hydrogen atoms of a chain saturated alkyl group such as hydroxyethyl, hydroxypropyl, hydroxybutyl with a hydroxy group; A halogen-substituted chain saturated alkyl group obtained by replacing a part of the hydrogen atoms of a chain saturated alkyl group such as fluoroethyl, difluoroethyl, chloroethyl, dichloroethyl, bromoethyl, dibromoethyl with a halogen; A chain unsaturated alkyl group such as vinyl, allyl, methallyl, crotyl, propargyl, and a chain unsaturated alkyl group obtained by replacing a part of the hydrogen atoms of the chain unsaturated alkyl group with an alkoxy group, a hydroxyl group or a halogen; Alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-t-butylcyclohexyl, tricyclodecyl, isobornyl, adamantyl, dicyclopentadienyl, and alicyclic hydrocarbon groups in which a part of hydrogen atoms thereof are substituted with an alkoxy group, a hydroxyl group, or a halogen; Aromatic hydrocarbon groups such as phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, 4-t-butylphenyl, benzyl, diphenylmethyl, diphenylethyl, triphenylmethyl, cinnamyl, naphthyl, anthracenyl, and alicyclic hydrocarbon groups in which a part of hydrogen atoms thereof are substituted with an alkoxy group, a hydroxyl group, or a halogen; etc.

Among these, a hydrogen atom or a chain saturated hydrocarbon group is preferred, and a hydrogen atom or a methyl group is preferred from the viewpoint of being less likely to cause steric hindrance during polymerization of the cyclopolymerizable compound.

In the general formula (1) and the general formula (2), ^R2 and ^R3 each independently represent a alkyl group having 1 to 4 carbon atoms, preferably a alkyl group having 1 to 2 carbon atoms, and particularly preferably a alkyl group having 1 carbon atoms, i.e., a methylene group. ^R2 and ^R3 may be the same or different from each other.

Furthermore, X in the general formula (1) and the general formula (2) represents a single bond, -O-, -S-, or ^NR4 ( ^R4 is a hydrogen atom, or a alkyl group having 1 to 4 carbon atoms). When X is a single bond, the ring formed when the cyclopolymerizable compound is polymerized becomes an aliphatic hydrocarbon ring. On the other hand, when X is -O-, -S-, or ^NR4 , the ring formed when the cyclopolymerizable compound is polymerized becomes an alicyclic heterocyclic structure. Among the above, X is preferably -O- or -S-, and particularly preferably -O-. If X is -O-, the polymer of the cyclopolymerizable compound and thus the sealing material are more likely to show flexibility. In addition, the strength of the sealing material is more likely to be improved by hydrogen bonding between the O atom and the base on the surface of the substrate.

Specific examples of the cyclopolymerizable compound represented by the general formula (1) include α-allyloxymethacrylic acid, methyl α-allyloxymethacrylic acid, ethyl α-allyloxymethacrylic acid, n-propyl α-allyloxymethacrylic acid, isopropyl α-allyloxymethacrylic acid, n-butyl α-allyloxymethacrylic acid, sec-butyl α-allyloxymethacrylic acid, t-butyl α-allyloxymethacrylic acid, n-pentyl α-allyloxymethacrylic acid, sec-pentyl α-allyloxymethacrylic acid, t-pentyl α-allyloxymethacrylic acid, n-hexyl α-allyloxymethacrylic acid, sec-hexyl α-allyloxymethacrylic acid, n-heptyl α-allyloxymethacrylic acid, n-octyl α-allyloxymethacrylic acid, sec-octyl α-allyloxymethacrylic acid, t-octyl α-allyloxymethacrylic acid, 2-ethylhexyl α-allyloxymethacrylic acid, α-allyloxymethacrylate decyl ester, α-allyloxymethacrylate nonyl ester, α-allyloxymethacrylate decyl ester, α-allyloxymethacrylate undecyl ester, α-allyloxymethacrylate dodecyl ester, α-allyloxymethacrylate tridecyl ester, α-allyloxymethacrylate tetradecyl ester, α-allyloxymethacrylate pentadecyl ester, α-allyloxymethacrylate hexadecyl ester, α-allyloxymethacrylate heptadecanyl ester, α-allyloxymethacrylate octadecyl ester, α-allyloxymethacrylate nonadecanyl ester, α-allyloxymethacrylate hexadecyl ester, α-allyloxymethacrylate tridecyl ester, α-allyloxymethacrylate methoxyethyl ester, α-allyloxymethacrylate methoxyethoxyethyl ester, α-allyloxymethacrylate methoxyethoxyethoxyethyl ester, α-allyloxymethacrylate 3-methoxybutyl ester, α-allyloxymethacrylate -allyloxy methacrylate ethoxyethyl, α-allyloxy methacrylate ethoxyethoxyethyl, α-allyloxy methacrylate phenoxyethyl, α-allyloxy methacrylate phenoxyethoxyethyl, α-allyloxy methacrylate hydroxyethyl, α-allyloxy methacrylate hydroxypropyl, α-allyloxy methacrylate hydroxybutyl, α-allyloxy methacrylate fluoroethyl, α-allyloxy methacrylate difluoroethyl, α-allyloxy methacrylate chloroethyl, α-allyloxy methacrylate dichloroethyl, α-allyloxy methacrylate bromoethyl, α-allyloxy methacrylate dibromoethyl, α-allyloxy methacrylate vinyl, α-allyloxy methacrylate allyl, α-allyloxy methacrylate methylallyl, α-allyloxy methacrylate crotonyl, α-allyloxy methacrylate propargyl, α-allyloxy methacrylate cyclopentyl, α-allyloxy Cyclohexyl methacrylate, 4-methylcyclohexyl α-allyloxymethacrylate, 4-tert-butylcyclohexyl α-allyloxymethacrylate, tricyclodecyl α-allyloxymethacrylate, isobornyl α-allyloxymethacrylate, adamantyl α-allyloxymethacrylate, dicyclopentadienyl α-allyloxymethacrylate, phenyl α-allyloxymethacrylate, methyl phenyl α-allyloxymethacrylate, dimethylphenyl α-allyloxymethacrylate, trimethylphenyl α-allyloxymethacrylate, 4-tert-butylphenyl α-allyloxymethacrylate, benzyl α-allyloxymethacrylate, diphenylmethyl α-allyloxymethacrylate, diphenylethyl α-allyloxymethacrylate, triphenylmethyl α-allyloxymethacrylate, cinnamyl α-allyloxymethacrylate, naphthyl α-allyloxymethacrylate, anthracene α-allyloxymethacrylate, and the like.

Among the above, α-allyloxymethylacrylic acid is preferred.

The amount of the cyclized polymerizable compound relative to the total amount of the curable compound is preferably 1 mass % or more and 30 mass % or less, more preferably 5 mass % or more and 27 mass % or less, and further preferably 10 mass % or more and 20 mass % or less. If the viscosity of the liquid crystal sealant is too low, when the uncured liquid crystal sealant (frame-shaped sealing pattern) and the liquid crystal material are sandwiched between a pair of substrates for bonding, the liquid crystal material is likely to enter the frame-shaped sealing pattern formed by the liquid crystal sealant (this phenomenon is also referred to as "inward rush" in this specification). In contrast, if the amount of the cyclized polymerizable compound is 30 mass % or less relative to the total amount of the curable compound, the viscosity of the liquid crystal sealant is more easily converged within the desired range, and the inward rush is less likely to occur when manufacturing a liquid crystal display panel. On the other hand, when the amount of the cyclopolymerizable compound is 1 mass % or more relative to the total amount of the curable compound, the adhesive strength of the obtained sealing material is more likely to be improved and low moisture permeability can be more easily achieved.

In addition, when the liquid crystal sealant contains a filler described later, the amount of the cyclopolymerizable material relative to the total amount of the filler is preferably 3 mass % or more and 300 mass % or less, more preferably 25 mass % or more and 200 mass % or less, and further preferably 50 mass % or more and 150 mass % or less. When the ratio of the cyclopolymerizable compound relative to the filler is within this range, the viscosity of the liquid crystal sealant is more likely to converge within a desired range, and the coating property of the liquid crystal sealant is more likely to become good.

(2) Other curable compounds Examples of curable compounds other than the above-mentioned cyclic polymerizable compounds included in the curable compound include epoxy compounds having one or more epoxy groups in the molecule, (meth)acrylic acid compounds having one or more (meth)acrylic acid groups in the molecule, and (meth)acrylic acid-modified epoxy compounds having (meth)acrylic acid groups and epoxy groups in the molecule. In addition, in this specification, the so-called (meth)acrylic acid group means methacrylic acid, acryl group, and both of these. In addition, the so-called (meth)acrylic acid means methacrylic acid, acrylic acid, and both of these, and the so-called (meth)acrylate means methacrylate, acrylate, and both of these.

·Epoxy compounds In this specification, epoxy compounds refer to compounds having one or more epoxy groups in the molecule. However, in this specification, epoxy compounds do not include compounds having epoxy groups and (meth)acryloyl groups. The curable compound may include only one epoxy compound or two or more.

In addition, the number of epoxy groups contained in one molecule of the epoxy compound may be one or more. If the curable compound contains an epoxy compound, the thermosetting property of the liquid crystal sealant tends to be good. Examples of epoxy compounds include well-known epoxy compounds, such as aromatic epoxy compounds, aliphatic epoxy compounds, and alicyclic epoxy compounds. Among these, aromatic epoxy compounds are preferred from the viewpoint of easily achieving low moisture permeability of the obtained sealant.

Examples of aromatic epoxy compounds include aromatic polyglycidyl ether compounds obtained by reacting aromatic diols represented by bisphenol A, bisphenol S, bisphenol F, bisphenol AD, etc., or diols obtained by modifying these aromatic diols using ethylene glycol, propylene glycol, alkane diol, etc., with epichlorohydrin; novolac-type polyglycidyl ether compounds obtained by reacting polyphenols represented by novolac resins derived from phenol or cresol and formaldehyde, polyalkenylphenols, or copolymers thereof, with epichlorohydrin; glycidyl ether compounds of xylylphenol resins, etc.

Among them, the preferred ones are cresol novolac type epoxy compounds, phenol novolac type epoxy compounds, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, trisphenol methane type epoxy compounds, trisphenol ethane type epoxy compounds, trisphenol type epoxy compounds, dicyclopentadiene type epoxy compounds, diphenyl ether type epoxy compounds or biphenyl type epoxy compounds.

Here, the epoxy compound may be in liquid or solid form. From the viewpoint of easily achieving low moisture permeability of the sealing material, a solid epoxy compound is preferred. 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 cyclotron method specified in Japanese Industrial Standard (JIS) K7234.

The weight average molecular weight of the epoxy compound is preferably 500 to 10000, more preferably 1000 to 5000. The weight average molecular weight of the epoxy compound is measured by gel permeation chromatography (GPC) in terms of polystyrene.

The total amount of the epoxy compound is preferably 5% by mass or more and 60% by mass or less, and more preferably 10% by mass or more and 40% by mass or less, relative to the total amount of the curable compound. If the amount of the epoxy compound is 5% by mass or more, the moisture permeability of the sealant is likely to be further reduced. On the other hand, if the amount of the epoxy compound is 60% by mass or less, the amount of the cyclic polymerizable compound is relatively large, and the photopolymerizability of the obtained sealant is likely to be further improved, or the adhesive strength is likely to be further improved.

·(Meth)acrylic compounds In this specification, (meth)acrylic compounds are compounds having one or more (meth)acrylic groups in the molecule. However, in this specification, (meth)acrylic compounds do not include the above-mentioned cyclic polymerizable compounds or compounds having (meth)acrylic groups and epoxy groups. The curable compound may include only one (meth)acrylic compound or two or more.

The number of (meth)acrylic acid groups contained in one molecule of a (meth)acrylic acid compound may be one or more. Examples of (meth)acrylic acid compounds containing one (meth)acrylic acid group in one molecule include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate.

Examples of (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 tri(2-hydroxyethyl)isocyanurate; di(meth)acrylates derived from a diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol; di(meth)acrylates derived from 1 mol of bisphenol A or bisphenol F; di(meth)acrylate of a diol obtained by adding 2 mol of ethylene oxide or propylene oxide to 1 mol of trihydroxymethylpropane (bisphenol A type or bisphenol F type epoxy (meth)acrylate); di(meth)acrylate or tri(meth)acrylate of a polyol obtained by adding 2 or 3 mol of ethylene oxide or propylene oxide to 1 mol of trihydroxymethylpropane; di(meth)acrylate of a diol obtained by adding 4 or more mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A; (Meth)acrylate; tri(2-hydroxyethyl) isocyanurate tri(meth)acrylate; trihydroxymethylpropane tri(meth)acrylate or its oligomer; pentaerythritol tri(meth)acrylate or its oligomer; poly(meth)acrylate of dipentaerythritol; tri(acryloxyethyl) isocyanurate; caprolactone-modified tri(acryloxyethyl) isocyanurate; caprolactone-modified tri(methacryloxyethyl) isocyanurate; alkyl-modified The present invention also includes poly (meth)acrylates of dipentaerythritol modified with caprolactone; poly (meth)acrylates of dipentaerythritol modified with caprolactone; hydroxytrimethylacetic acid neopentyl glycol di (meth)acrylate; caprolactone modified hydroxytrimethylacetic acid neopentyl glycol di (meth)acrylate; ethylene oxide modified phosphoric acid (meth)acrylate; ethylene oxide modified alkylated phosphoric acid (meth)acrylate; and oligomeric (meth)acrylates of neopentyl glycol, trihydroxymethylpropane and pentaerythritol. Among them, di (meth)acrylates of diols obtained by adding 2 mols of ethylene oxide or propylene oxide to 1 mol of bisphenol A or bisphenol F (bisphenol A type or bisphenol F type epoxy (meth)acrylates) are preferred.

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

The weight average molecular weight of the (meth)acrylic acid compound is preferably about 310 to 1000. The weight average molecular weight is, for example, a value measured by gel permeation chromatography (GPC) in terms of polystyrene.

Here, the total amount of the (meth)acrylic acid compound is preferably 3% by mass or more and 60% by mass or less, and more preferably 10% by mass or more and 40% by mass or less, relative to the total amount of the curable compound. If the total amount of the (meth)acrylic acid compound is 3% by mass or more, the light curing property of the liquid crystal sealant is likely to be good. On the other hand, if the total amount of the (meth)acrylic acid compound is 60% by mass or less, the amount of the cyclic polymerizable compound or the epoxy compound is relatively sufficient, and the adhesive strength or low moisture permeability of the obtained sealant is likely to be good.

·(Meth)acrylic acid modified epoxy compound In this specification, (meth)acrylic acid modified epoxy compound refers to a compound having one or more epoxy groups and one or more (meth)acrylic acid groups in the molecule. The curable compound may contain only one (meth)acrylic acid modified epoxy compound or may contain two or more.

The number of epoxy groups and (meth)acrylic groups in the (meth)acrylic modified epoxy compound is not particularly limited, and each may be only one or two or more. The (meth)acrylic modified epoxy compound has good compatibility with the epoxide-polymerizable compound or the epoxy-based compound and the acrylic-based compound. Therefore, if the (meth)acrylic modified epoxy compound is included as a curable compound, the compatibility of different types of curable compounds becomes very good.

The (meth)acrylic acid-modified epoxy compound is obtained by modifying at least one of the epoxy groups of a difunctional or higher epoxy compound with a (meth)acrylic acid group. The (meth)acrylic acid-modified epoxy compound can be obtained, for example, by reacting a difunctional or higher epoxy compound with (meth)acrylic acid in the presence of an alkaline catalyst.

The epoxy compound modified with a (meth)acryloyl group may be a multifunctional epoxy compound having two or more epoxy groups in the molecule. From the viewpoint of suppressing excessive crosslinking density and excessive reduction in the adhesive strength of the sealant, a difunctional epoxy compound is preferred. Examples of difunctional epoxy compounds include bisphenol-type epoxy compounds (bisphenol A type, bisphenol F type, 2,2'-diallylbisphenol A type, bisphenol AD type, and hydrogenated bisphenol type, etc.), biphenyl-type epoxy compounds, and naphthalene-type epoxy compounds. Among them, from the viewpoint of improving the coating properties of the liquid crystal sealant, bisphenol-type epoxy compounds of bisphenol A type and bisphenol F type are preferred. Compared with the (meth)acrylic acid-modified epoxy compound derived from the biphenyl ether type epoxy compound, the (meth)acrylic acid-modified epoxy compound derived from the bisphenol type epoxy compound has advantages such as excellent coating properties.

The ratio of the molar number of the (meth)acrylic group of the (meth)acrylic acid-modified epoxy compound to the molar number of the epoxy group is preferably 1 or more, more preferably 2 or more. By increasing the molar ratio of the (meth)acrylic group, elution of the liquid crystal sealant into the liquid crystal is easily suppressed.

The weight average molecular weight of the (meth)acrylic acid-modified epoxy compound measured by gel permeation chromatography (GPC) is preferably 300 to 500.

In addition, the amount of the (meth) acrylic acid modified epoxy compound is preferably 10% by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 60% by mass or less, relative to the total amount of the curable composition. If the amount of the (meth) acrylic acid modified epoxy compound is 10% by mass or more, it is easy to improve the compatibility of the cyclic polymerizable compound or the acrylic compound with the epoxy compound. On the other hand, if the amount of the (meth) acrylic acid modified epoxy compound is 80% by mass or less, the amount of the cyclic polymerizable compound, etc., is easy to become sufficient, and it is easier to achieve low moisture permeability or high adhesive strength in the obtained sealing material.

·Others The curable compound may further include curable compounds other than those described above within the scope that does not impair the purpose and effect of the present invention. Here, the total amount of the curable composition is preferably 40% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 80% by mass or less relative to the total amount of the liquid crystal sealant. If the total amount of the curable composition is 40% by mass or more, the leakage of liquid crystal can be easily suppressed by the sealant in the liquid crystal display panel. On the other hand, if the total amount of the curable composition is 90% by mass or less, the amount of the curing agent described later becomes sufficient, and it is easy to make the curability of the liquid crystal sealant better, or it is easy to adjust the viscosity of the liquid crystal sealant to the desired range.

1-2. Hardener The liquid crystal sealant contains a hardener. Examples of the hardener include a thermosetting agent for thermally hardening the liquid crystal sealant and a photopolymerization initiator for photohardening the liquid crystal sealant.

(1) Thermohardener Thermohardener is not particularly limited as long as it is a material that can thermally harden the epoxy compound or (meth)acrylic modified epoxy compound, but the thermohardener is preferably a latent thermohardener. The so-called latent thermohardener is a compound that does not harden epoxy compounds or (meth)acrylic modified epoxy compounds under normal storage conditions (room temperature, visible light, etc.), but hardens these compounds by heating. The latent thermohardener is preferably a hardener that can harden the epoxy group possessed by the curable compound by ring opening (hereinafter also referred to as "epoxy hardener").

From the viewpoint of improving the viscosity stability of the liquid crystal sealant and not impairing the moisture resistance of the obtained sealant, the melting point of the epoxy curing agent is preferably 50°C to 250°C, more preferably 100°C to 200°C, and further preferably 150°C to 200°C.

Examples of epoxy curing agents (thermocuring agents) include dihydrazide-based thermal latent curing agents, imidazole-based thermal latent curing agents, amine adduct-based thermal latent curing agents, and polyamine-based thermal latent curing agents. The liquid crystal sealant may include only one of these, or may include two or more of them.

Examples of the dihydrazide-based heat-latent curing agent include adipic acid dihydrazide, 1,3-bis(hydrazinocarbonylethyl)-5-isopropylhydantoin, 7,11-octadecadiene-1,18-dicarbonylhydrazide, dodecanedioic acid dihydrazide, sebacic acid dihydrazide, and the like.

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

Amine adduct-based heat latent curing agents are heat latent curing agents containing an addition compound obtained by reacting an amine compound having catalytic activity with an arbitrary compound. Examples of commercially available products of amine adduct-based heat 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 Precision Technologies Co., Ltd.).

The polyamine-based heat latent hardener is a heat latent hardener having a polymer structure obtained by reacting an amine with an epoxy resin, and commercially available examples thereof include Adeka Hardener EH4339S and Adeka Hardener EH4357S (both manufactured by Adeka Corporation).

Among the above, from the viewpoints of availability, compatibility with other components, etc., dihydrazide-based heat latent curing agents, amine adduct-based heat latent curing agents, polyamine-based heat latent curing agents, and imidazole-based heat latent curing agents are preferred, and dihydrazide-based heat latent curing agents are particularly preferred.

The amount of the thermosetting agent relative to the total amount of the liquid crystal sealant is preferably 3 mass % or more and 30 mass % or less, more preferably 3 mass % or more and 20 mass % or less, and further preferably 5 mass % or more and 20 mass % or less.

(2) Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is a compound used to initiate the curing (polymerization) of the cyclopolymerizable compound or acrylic compound, and further the (meth)acrylic acid-modified epoxy compound. The photopolymerization initiator may be a self-cleaving type photopolymerization initiator or a dehydrogenating type photopolymerization initiator. The liquid crystal sealant may contain only one type of photopolymerization initiator or may contain two or more types.

Examples of self-cleaving photopolymerization initiators include alkyl phenone compounds (e.g., benzyl dimethyl ketal compounds such as 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF, IRGACURE 651); α-aminoalkyl phenone compounds such as 2-methyl-2-oxo-(4-thiomethylphenyl)propane-1-one (manufactured by BASF, IRGACURE 907); α-Hydroxyphenyl alkyl ketone compounds such as hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF, IRGACURE 184); acyl phosphine oxide compounds such as 2,4,6-trimethylbenzoin diphenylphosphine oxide; titanium bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1 -ketone, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-oxolinyl (4-thiomethylphenyl) propane-1-one, 2-benzyl-2-dimethylamino-1-(4-oxolinylphenyl)-butanone; benzoylformic acid ester compounds such as methyl benzoate; benzoin, benzoin methyl ether; , benzoin isopropyl ether and other benzoin ether compounds; and oxime ester compounds such as 1,2-octanedione-1-[4-(phenylthio)-2-(O-benzoyl oxime)] (manufactured by BASF, IRGACURE OXE01), ethyl ketone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyl oxime) (manufactured by BASF, IRGACURE OXE02).

Examples of dehydrogenation-type photopolymerization initiators include benzophenone, methyl o-benzoylbenzoate-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetrakis(tert-butylcarbonylperoxide)benzophenone, 3,3'-dimethyl-4-methoxybenzophenone and the like; and thioxanthrone, 2-chlorothioxanthrone (manufactured by Tokyo Chemical Industry Co., Ltd.), 1-chloro-4-propoxythioxanthrone, 1-chloro-4-ethoxythioxanthrone (manufactured by Lambson Limited, Speedcure CPTX), 2-isopropyloxythioxanthrone (manufactured by Lambson Limited, Speedcure CPTX), and 1-isopropyloxythioxanthrone (manufactured by Lambson Limited, Speedcure CPTX). Thioxanthrone compounds such as 4-isopropylthioanthrone, 2,4-dimethylthioanthrone, 2,4-diethylthioanthrone (Lambson Limited, Speedcure DETX), and 2,4-dichlorothioanthrone; anthraquinone compounds such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-hydroxyanthraquinone (Tokyo Chemical Industry Co., Ltd., 2-Hydroxyanthraquinone), 2,6-dihydroxyanthraquinone (Tokyo Chemical Industry Co., Ltd., Anthraflavic Acid), and 2-hydroxymethylanthraquinone (Junsei Chemical Co., Ltd., 2-(Hydroxymethyl)anthraquinone); and benzoyl compounds.

The absorption wavelength of the photopolymerization initiator is not particularly limited, for example, it is preferred to absorb light with a wavelength of 360 nm or more. Among them, it is more preferred to absorb light in the visible light region, and it is particularly preferred to absorb light with a wavelength of 360 nm to 430 nm. If the photopolymerization initiator has an absorption wavelength within this range, the liquid crystal sealant can be cured by visible light irradiation, and the influence on the liquid crystal material can be greatly reduced. In addition, in this specification, the so-called "visible light region" is a wavelength range of 360 nm to 780 nm.

Examples of photopolymerization initiators that absorb light having a wavelength of 360 nm or more include alkyl phenoxide compounds, acylphosphine oxide photopolymerization initiators, titanocene photopolymerization initiators, oxime ester photopolymerization initiators, thioxanthone photopolymerization initiators, and anthraquinone photopolymerization initiators. Oxime ester photopolymerization initiators, thioxanthone photopolymerization initiators, and anthraquinone photopolymerization initiators are preferred, and oxime ester photopolymerization initiators are particularly preferred.

Furthermore, the structure of the photopolymerization initiator can be identified by combining high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC/MS) with nuclear magnetic resonance (NMR) or infrared (IR) analysis.

In addition, 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, the photopolymerization initiator is not easily eluted into the liquid crystal material when the liquid crystal sealant contacts the liquid crystal material. On the other hand, if the molecular weight is 5000 or less, the compatibility of the photopolymerization initiator and the curable compound is improved, and the photocurability of the liquid crystal sealant is easy to become good. The molecular weight of the photopolymerization initiator 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 can be determined as the "relative molecular mass" of the molecular structure of the main peak detected during analysis using high performance liquid chromatography (HPLC).

Specifically, a sample solution is prepared by dissolving a photopolymerization initiator in tetrahydrofuran (THF), and then subjected to high performance liquid chromatography (HPLC) measurement. Then, the area percentage of the detected peak (the ratio of the area of each peak to the total) is calculated to confirm the presence or absence of a main peak. The so-called 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 thioxanthrone 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).

The amount of the photopolymerization initiator is preferably 0.01 mass % to 10 mass % relative to the total amount of the compound having an unsaturated double bond in the curable compound (for example, the total amount of the cyclopolymerizable compound or (meth) acrylic acid compound, (meth) acrylic acid modified epoxy compound). If the amount of the photopolymerization initiator is 0.01 mass % or more relative to the total amount of the compound having an unsaturated double bond, the photocurability of the liquid crystal sealant tends to become good. On the other hand, if the content of the photopolymerization initiator is 10 mass % or less, the photopolymerization initiator is not easily eluted into the liquid crystal. The content of the photopolymerization initiator is more preferably 0.1% by mass to 5% by mass, further preferably 0.1% by mass to 3% by mass, and particularly preferably 0.1% by mass to 2.5% by mass, relative to the total amount of the compound having an unsaturated double bond in the curable compound.

1-3. Filler The liquid crystal sealant preferably contains a filler. If the liquid crystal sealant contains a filler, the viscosity of the liquid crystal sealant is more easily converged within the desired range. In addition, the moisture permeability of the obtained sealant is further reduced. Examples of fillers include inorganic fillers or core-shell type microparticles.

(1) Inorganic fillers In addition to imparting a specified hardness or linear expansion to the obtained sealant, inorganic fillers also have the function of further improving the low moisture permeability of the sealant.

Examples of the inorganic filler include calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, titanium nitride, aluminum oxide other than those mentioned above, zinc oxide, silica, potassium titanate, kaolin, talc, glass beads, sericite, activated clay, bentonite, aluminum nitride, silicon nitride, etc. Among these, silica and talc are preferred.

The shape of the inorganic filler may be a fixed shape such as a sphere, a plate, or a needle, or may be a non-fixed shape. When the inorganic filler is spherical, the average primary particle size of the inorganic filler is preferably 1.5 μm or less. In addition, the specific surface area of the inorganic filler is preferably 0.5 m ² /g or more and 20 m ² /g or less. The average primary particle size of the inorganic filler can be measured by the laser diffraction method described in JIS Z8825 (2013). The specific surface area of the filler is measured by the Brunauer-Emmett-Teller (BET) method described in JIS Z8830 (2013).

The amount of the inorganic filler in the liquid crystal sealant is preferably 2% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 20% by mass or less, and further preferably 5% by mass or more and 20% by mass or less relative to the total amount of the curable compound. The higher the content of the inorganic filler, the lower the moisture permeability of the obtained sealant. However, if the content is too high, the flexibility of the sealant may be impaired. Therefore, the above range is preferred.

(2) Core-shell type microparticles Core-shell type microparticles are microparticles that include a core having desired physical properties and a shell covering the core. The shell can improve compatibility with other components or partially react with other components.

Examples of core-shell type fine particles include organic fine particles having an elastic core made of conjugated diene rubber, silicone rubber, or the like, and a shell made of a polymer such as (meth)acrylate, vinyl monomer, or epoxy monomer.

In addition, another example of core-shell type microparticles also includes the following microparticles, wherein the microparticles have a core including an inorganic particle, and a shell including a polymer layer covering the core, and have a functional group including a carbon-carbon double bond on the surface. Examples of the functional group including a carbon-carbon double bond possessed by the core-shell type microparticles include vinyl, allyl, acrylic, methacrylic, etc. Furthermore, examples of the core in the core-shell type microparticles include particles that are the same as the inorganic filler. Among them, from the viewpoint of excellent thermal stability, silica particles are preferred.

The amount of the core-shell type microparticles relative to the basic amount of the curable compound is preferably 2 mass % or more and 30 mass % or less, more preferably 2 mass % or more and 20 mass % or less, and further preferably 5 mass % or more and 20 mass % or less. If the content of the core-shell type microparticles is within this range, it is easy to adjust the physical properties of the obtained sealing material to the desired range.

(3) Others Within the scope of not impairing the purpose and effect of the present invention, fillers other than those mentioned above may be included, for example, organic microparticles other than core-shell structures may also be included.

As described above, if the amount of filler and the amount of cyclopolymerizable compound satisfy the prescribed relationship, the physical properties of the liquid crystal sealant such as viscosity are easily converged within the desired range, the coating property of the liquid crystal sealant becomes good, or it is difficult to generate inward impact when manufacturing a liquid crystal display panel. Here, the total amount of filler is preferably 5 mass% or more and 40 mass% or less, and more preferably 10 mass% or more and 30 mass% or less relative to the total amount of the liquid crystal sealant. If the total amount of filler is within the above range, it is easy to adjust various physical properties of the liquid crystal sealant to the desired range.

1-4. Others In addition to the above-mentioned components, the liquid crystal sealant may also include a thermal free radical generator, organic microparticles, coupling agents such as silane coupling agents, ion scavengers, ion exchange agents, leveling agents, pigments, dyes, sensitizers, plasticizers, and defoaming agents, etc.

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

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

The amount of the silane coupling agent is preferably 0.01 mass % or more and 5 mass % or less relative to the total amount of the liquid crystal sealant. If the content of the silane coupling agent is 0.01 mass % or more, the bonding strength between the sealant and the substrate can be further improved.

The liquid crystal sealant may further include a spacer for adjusting the gap of the liquid crystal display panel.

The total amount of other components is preferably 0.1 mass % or more and 50 mass % or less relative to the total amount of the liquid crystal sealant. If the total amount is 50 mass % or less, the viscosity of the liquid crystal sealant is unlikely to increase excessively, and the coating stability of the liquid crystal sealant is unlikely to be impaired.

1-5. Viscosity of liquid crystal sealant The viscosity of the liquid crystal sealant at 25°C and 2.5 rpm based on an E-type viscometer is preferably 200 Pa·s to 450 Pa·s, and more preferably 300 Pa·s to 400 Pa·s. If the viscosity is within the above range, the coating property of the sealant using a dispenser becomes good. In addition, if the viscosity of the liquid crystal sealant is within this range, the above-mentioned inrush is less likely to occur.

2. Liquid crystal display panel and its manufacturing method The liquid crystal display panel of the present invention comprises: a pair of substrates; a liquid crystal layer sandwiched between the pair of substrates; and a frame-shaped sealing material disposed between the pair of substrates for sealing the liquid crystal layer.

One of the substrates in the pair is set as a display substrate, and the other substrate is set as an opposite substrate. These are all transparent substrates. The material of the transparent substrate can be inorganic materials such as glass, or plastics such as polycarbonate, polyethylene terephthalate, polyether ether and polymethyl methacrylate (PMMA).

Thin Film Transistors (TFT), color filters, black matrix, etc. can be arranged on the surface of a pair of substrates (display substrate and counter substrate). An alignment film is usually arranged on the surface of the display substrate or the counter substrate. The alignment film is a film containing a known organic alignment agent or an inorganic alignment agent.

The liquid crystal layer is a layer including a liquid crystal material sealed in a region surrounded by a pair of substrates and a sealant. The liquid crystal material is the same as a known liquid crystal material.

The sealing material is a frame-shaped member disposed between a pair of substrates and used to seal the liquid crystal. The sealing material is a cured product of the liquid crystal sealant.

The liquid crystal display panel is manufactured using the liquid crystal sealant of the present invention. The manufacturing method of the liquid crystal display panel generally includes a liquid crystal dropping process and a liquid crystal injection process, but the liquid crystal display panel of the present invention is preferably manufactured using the liquid crystal dropping process.

The manufacturing method of a liquid crystal display panel using a liquid crystal drop process includes the following steps: 1) preparing a pair of substrates; 2) forming a frame-shaped sealing pattern on one of the pair of substrates by using the liquid crystal sealant; 3) applying a dummy sealant on the outer side of the frame-shaped sealing pattern to form a dummy sealing pattern; 4) dripping liquid crystal material to the inner side of the area surrounded by the frame-shaped sealing pattern on one of the substrates and/or the corresponding area on the other substrate when the frame-shaped sealing pattern and the dummy sealing pattern are not hardened; 5) overlapping one of the substrates with the other substrate via the liquid crystal material in a reduced pressure environment; and 6) hardening the frame-shaped sealing pattern and the dummy sealing pattern. Furthermore, both step 2) and step 3) can be performed first. In addition, after step 6), a step of removing the area where the virtual sealing pattern is formed can be further performed.

In step 1), a display substrate and a counter substrate having a matrix of TFTs, a color filter, a black matrix and an alignment film are usually prepared.

In step 2), the area to which the liquid crystal sealant is applied can be appropriately selected according to the structure of the liquid crystal display panel. The method of applying the liquid crystal sealant is not particularly limited as long as the liquid crystal sealant can be applied with a desired width, and for example, the liquid crystal sealant can be applied by a dispenser or the like.

In step 3), the area where the dummy sealant is applied can also be appropriately selected according to the structure of the liquid crystal display panel. The dummy sealant can be the same as the liquid crystal sealant or different. Furthermore, when the dummy sealant is different from the liquid crystal sealant, the composition of the dummy sealant is not particularly limited and is the same as the known dummy sealant. The dummy sealant can also be applied by a dispenser or the like.

Here, the virtual sealing pattern is arranged with a gap between the sealing patterns. If the virtual sealing pattern is formed, when a pair of substrates are overlapped in the step 5) described later, a decompression space is formed between the virtual sealing member and the sealing material. Thereby, the pair of substrates can be firmly fixed.

In step 4), the liquid crystal material is dripped into a predetermined area. Here, the state in which the frame-shaped sealing pattern and the dummy sealing pattern are not hardened refers to the state in which the hardening reaction of the liquid crystal sealant or the dummy sealant has not proceeded to the gelation point. Therefore, in step 4), in order to suppress the dissolution of the liquid crystal sealant into the liquid crystal, the frame-shaped sealing pattern may be irradiated with light or heated in advance and semi-hardened. In addition, when the liquid crystal is dripped onto another substrate in step 4), when two substrates with alignment films are overlapped in step 5), the liquid crystal is dripped in such a way that the liquid crystal is contained inside the frame-shaped sealing pattern.

In step 5), one of the substrates is overlapped with the other substrate via the liquid crystal material in a reduced pressure environment. Since the liquid crystal material is overlapped in a reduced pressure environment in this way, the obtained sealant and the dummy seal are in a reduced pressure state as described above. However, when a pair of substrates are overlapped in step 5), the frame-shaped sealing pattern is not cured. Therefore, when a general liquid crystal sealant is used, the liquid crystal material sometimes enters the inside of the frame-shaped seal frame-shaped sealing pattern (causing inward impact). In contrast, in the liquid crystal sealant, such inward impact is not easy to occur. In addition, especially when the liquid crystal sealant contains fillers, inward impact is less likely to occur.

In step 6), curing by light irradiation and subsequent curing by heating may be performed. By performing curing by light irradiation, the liquid crystal sealant (and dummy sealant) can be cured in a short time, thereby suppressing the dissolution of the liquid crystal sealant into the liquid crystal. By combining curing by light irradiation with curing by heating, damage to the liquid crystal layer caused by light can be reduced compared to the case of performing curing by light irradiation alone.

The irradiated light can be appropriately selected according to the type of photopolymerization initiator in the liquid crystal sealant (and dummy sealant), preferably light in the visible light region, for example, preferably light with a wavelength of 370 nm or more and 450 nm or less. The reason is that the light of the wavelength causes relatively little damage to the liquid crystal material or the drive electrode. The irradiation of light can use a known light source that emits ultraviolet rays or visible light. In the case of irradiating visible light, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a xenon lamp, a fluorescent lamp, etc. can be used.

The light irradiation energy may be any energy that can cure the curable compound. The light curing time also depends on the composition of the liquid crystal sealant, and is, for example, about 10 minutes.

The heat curing temperature also depends on the composition of the liquid crystal sealant or the dummy sealant, for example, it is 120°C, and the heat curing time is about 2 hours. [Example]

Hereinafter, the present invention will be described with reference to the embodiments. The scope of the present invention is not limited to the embodiments.

1. Preparation of materials As materials used in the examples and comparative examples, the following compounds were prepared.

(1) Curable compound (cyclopolymerizable compound) Curable compound (A-1): a cyclopolymerizable compound represented by the following general formula (1A) (trade name "AOMA", manufactured by Nippon Catalyst Co., Ltd.) [Chemical 3]

(Other curable compounds) Curable compound (A-2): Bisphenol A diacrylate (manufactured by Daicel-Allnex, Ebecryl 3700) Curable compound (A-3): Tris-(2-acryloyloxyethyl) isocyanurate represented by the following formula (manufactured by Shin-Nakamura Chemical Industries, Ltd., A-9300-2CL) [Chemical 4] Curable compound (A-4): ethoxylated bisphenol A diacrylate represented by the following formula (manufactured by Shin-Nakamura Chemical Industries, Ltd., A-BPE-4) [Chemical 5] (where m+n=4) Curable compound (A-5): Bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, YL983U) Curable compound (A-6): Acrylic modified epoxy resin (manufactured by KSM, BAEM-50)

(2) Hardener · Thermohardener: Amine adduct type hardener (manufactured by Ajinomoto Precision Technology Co., Ltd., PN-50) · Photopolymerization initiator: Oxime ester photopolymerization initiator (manufactured by BASF Japan, IRGACURE OXE02)

(3) Filler · Silica particles (manufactured by Admatechs, SO-C1) · Core-shell microparticles (manufactured by Aica Industries, F351)

(4) Silane coupling agent ·KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.)

2. Preparation of liquid crystal sealant (Example 1) 100 parts by mass of curable compound (A-1), 70 parts by mass of curable compound (A-2), 100 parts by mass of curable compound (A-5), 400 parts by mass of curable compound (A-6), 130 parts by mass of thermosetting agent, 10 parts by mass of photopolymerization initiator, 100 parts by mass of silica particles, 100 parts by mass of core-shell type microparticles, and 10 parts by mass of silane coupling agent were mixed using a three-roll mill to obtain a liquid crystal sealant.

(Example 2 to Example 9 and Comparative Example 1, Comparative Example 2) A liquid crystal sealant was prepared in the same manner as in Example 1 except that the composition was changed to that shown in Table 1.

3. Evaluation The obtained cured product of the liquid crystal sealant was evaluated for adhesive strength, moisture permeability (low moisture permeability), inward impact resistance, and drawing properties by the following methods. The results are shown in Table 1.

(Adhesion Strength) The obtained liquid crystal sealant was formed into a 38 mm × 38 mm square frame-shaped seal pattern (cross-sectional area 2500 μm 2 ) on a 40 mm × 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC) on which a transparent electrode and an alignment film were previously formed using a dispenser (Shotmaster, manufactured by Musashi Engineering ⁾ . Then, the paired glass substrates were bonded together under reduced pressure in a manner perpendicular to the glass substrate on which the frame-shaped seal pattern was formed, and then bonded together by opening the atmosphere. Then, the two bonded glass substrates were kept in a light-shielding box for 1 minute, and then irradiated with 3000 mJ/ ^cm2 of visible light (light with a wavelength of 370 nm to 450 nm), and then heated at 120°C for 1 hour to cure the frame-shaped sealing pattern, thereby obtaining a test piece. For the portion of the obtained test piece that is 4.5 mm outside the corner of the frame-shaped sealing pattern, an indentation tester (Model 210, manufactured by Intesco) was used to perform vertical indentation at a speed of 5 mm/minute. The above operation was performed on 10 glass substrates (n=10), and the number of glass substrates that were cracked was counted. Then, the bonding strength was evaluated according to the following criteria. ◎: The number of cracks on the glass substrate is 10 pieces○: The number of cracks on the glass substrate is 6 to 9 pieces△: The number of cracks on the glass substrate is 1 to 5 pieces×: The number of cracks on the glass substrate is 0 pieces. The more cracks on the glass substrate, the higher the bonding strength. If it is △ or above, it is a level that is not a problem in practical use and is judged to be good.

(Moisture resistance) The obtained liquid crystal sealant was applied to a release paper with a thickness of 100 μm using an applicator. The applied liquid crystal sealant was then placed in a nitrogen replacement container and flushed with nitrogen for 5 minutes, then irradiated with 3000 mJ/ ^cm2 of light (light calibrated with a 365 nm wavelength sensor), and then heated at 120°C for 1 hour to prepare a cured film.

Two hardened films are placed on an aluminum cup filled with calcium chloride (anhydrous) as a moisture absorbent, and then an aluminum ring is placed and screwed, and then the initial weight of the entire aluminum cup is measured. After that, the aluminum cup is placed in a constant temperature bath set at 60℃ and 90%Rh. After 24 hours, the aluminum cup is taken out and the weight is measured. The obtained weight value is substituted into the following calculation formula to calculate the moisture permeation. Calculation formula: Moisture permeation = (weight after test - weight before test) × film thickness / (film area × 100) Then, evaluation is performed based on the following criteria. ◎: Moisture permeability is 60 g/m2 or ^less ○: Moisture permeability exceeds 60 g/ ^m2 and is 80 g/m2 or ^less △: Moisture permeability exceeds 80 g/ ^m2 and is 100 g/ ^m2 or less ×: Moisture permeability exceeds 100 g/ ^m2 If it is △ or above, it is a level that does not cause any practical problems and is judged to be good.

(Inrush resistance) Using a dispenser (Shotmaster, manufactured by Musashi Engineering), the obtained liquid crystal sealant was formed into a 24 mm × 24 mm, 0.5 mm line width quadrilateral frame-shaped seal pattern (cross-sectional area 2500 μm ² ) on a 40 mm × 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC) on which a transparent electrode and an alignment film were previously formed. Furthermore, a 38 mm × 38 mm, 1 mm line width quadrilateral frame-shaped dummy seal pattern was formed around it using the liquid crystal sealant. Then, droplets of liquid crystal (MLC-3007; manufactured by Merck) (dropping amount 2.0 μl) were dripped into the frame of the frame-shaped seal pattern. Next, the paired glass substrates were bonded under reduced pressure in a manner perpendicular to the glass substrates formed with the frame-shaped sealing pattern and the dummy sealing pattern, and then bonded in an open atmosphere. The two bonded glass substrates were then kept in a light-shielding box for 1 minute, and then irradiated with 3000 mJ/ ^cm2 of light containing visible light (light with a wavelength of 370 nm to 450 nm), and then heated at 120°C for 1 hour to harden the seal, thereby obtaining a test piece. The interface between the sealing material and the liquid crystal was then observed using a polarizing microscope and evaluated according to the following criteria. The results are shown in Table 1. ◎: The penetration of the liquid crystal material into the liquid crystal sealant (cured material) in the width direction (sealing path diameter) is 0.1 mm or less ○: The sealing path diameter exceeds 0.1 mm and is 0.3 mm or less △: The sealing path diameter exceeds 0.3 mm and is 0.5 mm or less ×: The sealing path diameter exceeds 0.5 mm

(Drawing property) The obtained liquid crystal sealant was filled into a 10 cc syringe, degassed, and then filled into a dispenser (Shotmaster; manufactured by Musashi Engineering). The dispenser was used to draw on a glass substrate at a speed of 4 cm per second. Drawing property (drawing property) was evaluated according to the following criteria. ○: No broken line or thin line △: No broken line, but there are one or more thin line ×: There are one or more broken line

[Table 1] Embodiment Comparison Example 1 2 3 4 5 6 7 8 9 1 2 Composition Hardening compound Cyclic polymerizable compounds A-1 100 50 200 6 240 5 250 240 100 (Meth) acrylic acid compounds A-2 70 70 70 70 70 70 70 70 70 70 70 A-3 100 A-4 100 Epoxide compounds A-5 100 100 100 100 100 100 100 100 100 100 100 (Meth)acrylic acid modified epoxy compound A-6 400 400 400 400 400 400 400 400 400 400 400 Hardener Heat hardener 130 130 130 130 130 130 130 130 130 130 130 Photopolymerization initiator 10 10 10 10 10 10 10 10 10 10 10 filler Silica particles (inorganic filler) 100 100 100 100 40 100 100 30 0 100 100 Core-shell microparticles 100 100 100 100 40 100 100 30 0 100 100 Silane coupling agent 10 10 10 10 10 10 10 10 10 10 10 Total 1020 970 1120 926 1040 925 1170 1020 820 1020 1020 Total amount of cyclopolymerizable compounds/hardening compounds 15% 8% 26% 1% 30% 1% 30% 30% 15% 0% 0% Total amount of cyclopolymerizable compound/filler 50% 25% 100% 3% 300% 3% 125% 400% - 0% 0% Reviews Bonding strength ◎ ○ ◎ ○ ◎ △ ◎ ◎ ○ △ × Low moisture permeability ◎ ◎ ○ ◎ ○ ◎ △ ○ ○ × △ Intrusion resistance ◎ ◎ ○ ◎ ○ ◎ ○ △ △ ◎ ◎ Descriptive ○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○

As shown in Table 1, when the liquid crystal sealant contains the cyclopolymerizable compound (curable compound (A-1)) represented by the general formula (1), the intrusion resistance and the drawing property are good, and the obtained sealant has high adhesive strength and low moisture permeability (Examples 1 to 9). Due to the polymer structure of the cyclopolymerizable compound, it is possible to achieve both high adhesive strength and low moisture permeability, which was particularly difficult in the past.

In contrast, when the curable compound (A-3) and the curable compound (A-4) having structures different from those of the general formula (1) were used, the results of either the adhesive strength or the low moisture permeability were inferior (Comparative Examples 1 and 2).

Furthermore, in the examples, when the amount of the cyclopolymerizable compound is 3 mass % or more and 300 mass % or less relative to the total amount of the filler, the inrush resistance is particularly likely to be good (Examples 1 to 7). It is believed that the viscosity of the liquid crystal sealant is within an appropriate range, and the liquid crystal is unlikely to enter the frame-shaped sealing pattern during lamination in a vacuum environment.

This application claims priority based on Japanese Patent Application No. 2023-034812 filed on March 7, 2023. All contents described in the specification of that application are incorporated herein by reference. [Industrial Applicability]

The present invention provides a liquid crystal sealant capable of producing a sealant having strong adhesive strength and low moisture permeability, a liquid crystal display panel using the same, and a method for producing the same, and is therefore very useful in the field of manufacturing liquid crystal display panels.

without

without

Claims (15)

A liquid crystal sealant comprises a curable compound and a curing agent, wherein the curable compound comprises a cyclopolymerizable compound represented by the following general formula (1): (In the general formula (1), ^R1 represents a hydrogen atom or a alkyl group having 1 to 30 carbon atoms, ^R2 and ^R3 each independently represent a alkyl group having 1 to 4 carbon atoms, and X represents a single bond, -O-, -S- or ^NR4 ( ^R4 is a hydrogen atom or a alkyl group having 1 to 4 carbon atoms)). The liquid crystal sealant as described in claim 1, wherein, the amount of the cyclopolymerizable compound is greater than 1 mass % and less than 30 mass % relative to the total amount of the curable compound. The liquid crystal sealant as described in claim 1 further comprises a filler, and the amount of the cyclopolymerizable compound relative to the total amount of the filler is greater than 3% by mass and less than 300% by mass. The liquid crystal sealant as described in claim 3, wherein the filler contains core-shell type microparticles. The liquid crystal sealant as described in claim 1, wherein, the curable compound further comprises an epoxy compound having an epoxy group, the curing agent comprises at least one thermal curing agent selected from the group consisting of a dihydrazide thermal latent curing agent, an imidazole thermal latent curing agent, an amine adduct thermal latent curing agent and a polyamine thermal latent curing agent. The liquid crystal sealant as described in claim 1 further comprises a silane coupling agent. The liquid crystal sealant as described in claim 1, wherein the curing agent contains at least one photopolymerization initiator selected from the group consisting of oxime ester photopolymerization initiators, thioxanthrone photopolymerization initiators, and anthraquinone photopolymerization initiators. The liquid crystal sealing agent according to claim 1, wherein the moisture permeability of the cured product when applied to a thickness of 100 μm and irradiated with 3000 mJ/cm ² of light calibrated by a sensor having a wavelength of 365 nm and heated at 120° C. for 1 hour is 80 g/m ² or less. The liquid crystal sealant as described in claim 1, wherein the sealing path diameter measured by the following method is less than 0.5 mm, (Method for measuring the sealing path diameter) (i) on a glass substrate with an alignment film, a frame-shaped sealing pattern with a line width of 0.5 mm and a size of 24 mm×24 mm is formed by using the liquid crystal sealant; (ii) a virtual sealing pattern with a size of 38 mm×38 mm is formed by using the liquid crystal sealant in a manner surrounding the frame-shaped sealing pattern; (iii) liquid crystal is dripped into the frame-shaped sealing pattern; (iv) the glass substrate with the alignment film and an opposing substrate are overlapped under reduced pressure in a manner of sandwiching the frame-shaped sealing pattern, and the layers are released to the atmosphere to obtain a laminate; (v) the laminate is kept in a light-shielding box for 1 minute and irradiated with 3000 mJ/cm ² with a wavelength of 370 nm to 450 nm; (vi) heating the laminate at 120° C. for 1 hour to cure the liquid crystal sealant; (vii) confirming the boundary of the liquid crystal sealant and the liquid crystal after curing with a polarizing microscope, and setting the length of the liquid crystal entering along the width direction of the liquid crystal sealant after curing as the sealing path. A liquid crystal display panel comprises: a pair of substrates; a liquid crystal layer sandwiched between the pair of substrates; and a frame-shaped sealing material disposed between the pair of substrates for sealing the liquid crystal layer, wherein the sealing material is a cured product of the liquid crystal sealant described in any one of claims 1 to 9. A method for manufacturing a liquid crystal display panel comprises the following steps: Preparing a pair of substrates; Applying a liquid crystal sealant as described in any one of claims 1 to 9 on one of the substrates to form a frame-shaped sealing pattern; Applying a dummy sealant on the outer side of the frame-shaped sealing pattern to form a dummy sealing pattern; When the frame-shaped sealing pattern and the dummy sealing pattern are not hardened, dripping a liquid crystal material onto the inner side of the frame-shaped sealing pattern and/or onto another substrate; In a reduced pressure environment, overlapping the pair of substrates via the liquid crystal material; and Hardening the frame-shaped sealing pattern and the dummy sealing pattern. The manufacturing method of a liquid crystal display panel as described in claim 11, wherein the dummy sealant in the step of forming a dummy seal pattern is a liquid crystal sealant as described in any one of claims 1 to 9. A method for manufacturing a liquid crystal display panel as described in claim 12, wherein light is irradiated in the step of hardening the frame-shaped sealing pattern and the dummy sealing pattern. A method for manufacturing a liquid crystal display panel as described in claim 13, wherein the light includes a wavelength in the visible light region. A method for manufacturing a liquid crystal display panel as described in claim 13, wherein, in the step of hardening the frame-shaped sealing pattern and the dummy sealing pattern, heating is further performed.