WO2024185743A1 - Liquid crystal sealing agent, liquid crystal display panel using same, and method for manufacturing liquid crystal display panel - Google Patents

Abstract

The present invention addresses the problem of providing a liquid crystal sealing agent that enables fabrication of a sealing material having adhesive strength and low moisture permeability. This liquid crystal sealing agent for solving said problem comprises a curable compound and a curing agent, the curable compound including a cyclic-polymerizable 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 method for manufacturing the same.

　A liquid crystal display panel typically comprises a pair of substrates, a frame-shaped sealant disposed between the substrates, and liquid crystal material sealed within the area surrounded by the sealant. Such liquid crystal display panels are manufactured using the liquid crystal dripping method.

In the liquid crystal dropping method, first, a liquid crystal sealant is applied to one of a pair of substrates using a dispenser to form a rectangular frame-shaped sealing pattern. Next, while the liquid crystal sealant is in an uncured state, liquid crystal material is dropped into the frame-shaped sealing pattern or into the corresponding area of the other substrate. The substrates are then overlapped under vacuum, and the frame-shaped sealing pattern is irradiated with ultraviolet light or other light to cause a temporary cure. After that, the material is heated to cause the full cure, and the liquid crystal display panel is produced.

　In recent years, as the frame widths of liquid crystal display panels have become narrower, there has been a demand for narrower line widths in encapsulants. Therefore, even when the width is narrowed, encapsulants are required to have the same or better adhesion to substrates and moisture resistance as conventional encapsulants, i.e., they must have a high degree of both adhesive strength and low moisture permeability.

A known method for improving the low moisture permeability of sealing materials is to incorporate inorganic fillers such as talc or alumina. For example, Patent Document 1 proposes a sealant for liquid crystal display elements that contains a curable resin, a radical polymerization initiator, a heat curing agent, and alumina. Patent Document 2 proposes a sealant for liquid crystal display elements that contains a curable resin, a radical polymerization initiator, a heat curing agent, and alumina or talc with an aspect ratio of 2 or more.

JP 2016-218447 A JP 2013-214056 A

However, when mixing inorganic fillers, although the resulting sealant has good low moisture permeability, its flexibility is impaired, which means that the adhesive strength is easily reduced. As such, adhesive strength and low moisture permeability are usually in a trade-off relationship, and it has been difficult to achieve both with conventional liquid crystal sealants.

The present invention was made in consideration of the above problems, and aims to provide a liquid crystal sealant that can be used to create a sealant with high adhesive strength and low moisture permeability, as well as a liquid crystal display panel and a method for manufacturing the same that use the same.

　（一般式（１）において、Ｒ^１は、水素原子、または炭素数１以上３０以下の炭化水素基を表し、Ｒ^２およびＲ^３はそれぞれ独立に、炭素数１以上４以下の炭化水素基を表し、Ｘは、単結合、－Ｏ－、－Ｓ－、またはＮＲ^４（Ｒ^４は水素原子、または炭素数１以上４以下の炭化水素基）を表す） The present invention provides a liquid crystal sealing material comprising a curable compound and a curing agent, wherein the curable compound comprises a cyclopolymerizable compound represented by the following general formula (1):

(In general formula (1), R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, R ² and R ³ each independently represent a hydrocarbon group having 1 to 4 carbon atoms, and X represents a single bond, -O-, -S-, or NR ⁴ (R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms).

The present invention further provides a liquid crystal display panel having a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and a frame-shaped sealant disposed between the pair of substrates for sealing the liquid crystal layer, the sealant being a cured product of the liquid crystal sealant described above.

The present invention further provides a method for manufacturing a liquid crystal display panel, comprising the steps of: preparing a pair of substrates; applying the above-described liquid crystal sealant onto one substrate to form a frame-shaped sealing pattern; applying a dummy sealant onto the outside of the frame-shaped sealing pattern to form a dummy seal pattern; dripping liquid crystal material onto the inside of the frame-shaped sealing pattern and/or onto the other substrate while the frame-shaped sealing pattern and the dummy seal pattern are in an uncured state; overlapping the pair of substrates with the liquid crystal material interposed therebetween under a reduced pressure atmosphere; and curing the frame-shaped sealing pattern and the dummy seal pattern.

The liquid crystal sealant of the present invention makes it possible to produce a sealing material with high adhesive strength and low moisture permeability.

In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower and upper limits.

1. Liquid Crystal Sealing Agent The liquid crystal sealing agent of the present invention only needs to contain a curable resin and a curing agent for curing the curable resin, and may further contain a filler, a silane coupling agent, and the like, as necessary.

As described above, in the conventional liquid crystal sealant, it was difficult to achieve both high adhesive strength and low moisture permeability in the cured sealant. In contrast, according to the intensive study by the present inventors, it has become clear that high adhesive strength and low moisture permeability can be achieved by including a cyclopolymerizable compound having a specific structure in the liquid crystal sealant. The structure of the cyclopolymerizable compound will be described in detail later, but when the cyclopolymerizable compound is polymerized, a structure in which a plurality of alicyclic structures are linked by ethylene chains is formed. With such a polymer, the rigid alicyclic structure can suppress the intrusion of moisture into the sealant. On the other hand, the ethylene chains in the polymer provide moderate flexibility. Therefore, when an external force is applied to the liquid crystal display panel, it is possible to deform the sealant in accordance with the substrate, and the adhesive strength between the substrate and the sealant becomes very high.
Hereinafter, each component contained in the liquid crystal sealing material of the present invention will be described in detail.

1-1. Curable Compound In this specification, the curable compound refers to a compound that is polymerized and cured by energy such as heat or light. The curable compound may contain at least the cyclopolymerizable compound described below, but it is preferable that the curable compound further contains an epoxy compound, a (meth)acrylic compound, a (meth)acrylic-modified epoxy compound, or the like, which will be described later, together with the cyclopolymerizable compound.

　一般式（１）および（２）において、Ｒ^１は、水素原子、または炭素数１以上３０以下の炭化水素基を表す。炭化水素基の炭素数は、１以上４以下がより好ましい。 (1) Cyclopolymerizable Compound As described above, the curable compound contains a cyclopolymerizable compound having a structure represented by the following general formula (1). The curable compound may contain only one type of the cyclopolymerizable compound, or may contain two or more types of the cyclopolymerizable compound. The cyclopolymerizable compound becomes a polymer having a repeating unit represented by the following general formula (2) by polymerization of these.

In formulae (1) and (2), R ¹ represents a hydrogen atom or a hydrocarbon group having from 1 to 30 carbon atoms. The number of carbon atoms in the hydrocarbon group is preferably from 1 to 4.

Specific examples of the group represented by R ¹ include a hydrogen atom; a chain saturated hydrocarbon group such as methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n-amyl, s-amyl, t-amyl, n-hexyl, s-hexyl, n-heptyl, n-octyl, s-octyl, t-octyl, 2-ethylhexyl, capryl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, pentadecyl, cetyl, heptadecyl, stearyl, nonadecyl, eicosyl, seryl, and melissyl;
alkoxy-substituted chain saturated hydrocarbon groups in which some of the hydrogen atoms of a chain saturated hydrocarbon group have been replaced with an alkoxy group, such as methoxyethyl, methoxyethoxyethyl, methoxyethoxyethoxyethyl, 3-methoxybutyl, ethoxyethyl, ethoxyethoxyethyl, phenoxyethyl, and phenoxyethoxyethyl;
hydroxy-substituted chain saturated hydrocarbon groups in which some of the hydrogen atoms of a chain saturated hydrocarbon group have been replaced with hydroxy groups, such as hydroxyethyl, hydroxypropyl, and hydroxybutyl;
halogen-substituted chain saturated hydrocarbon groups in which part of the hydrogen atoms of a chain saturated hydrocarbon group has been replaced with halogen, such as fluoroethyl, difluoroethyl, chloroethyl, dichloroethyl, bromoethyl, and dibromoethyl;
linear unsaturated hydrocarbon groups such as vinyl, allyl, methallyl, crotyl, propargyl, and the like, and linear unsaturated hydrocarbon groups in which some of the hydrogen atoms have been replaced by alkoxy groups, hydroxy groups, or halogens;
alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-t-butylcyclohexyl, tricyclodecanyl, isobornyl, adamantyl, dicyclopentadienyl, and the like, and alicyclic hydrocarbon groups in which some of the hydrogen atoms have been replaced by alkoxy groups, hydroxy groups, or halogens;
Examples of aromatic hydrocarbon groups include phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, 4-t-butylphenyl, benzyl, diphenylmethyl, diphenylethyl, triphenylmethyl, cinnamyl, naphthyl, anthranyl, and the like, as well as aromatic hydrocarbon groups in which some of the hydrogen atoms have been replaced by alkoxy groups, hydroxy groups, or halogens.

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 preventing steric hindrance during polymerization of the cyclopolymerizable compound.

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

Furthermore, X in the above general formulas (1) and (2) represents a single bond, -O-, -S-, or NR ⁴ (R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms). When X is a single bond, the ring formed when the cyclopolymerizable compound is polymerized is an aliphatic hydrocarbon ring. On the other hand, when X is -O-, -S-, or NR ⁴ , the ring formed when the cyclopolymerizable compound is polymerized is an alicyclic heterocyclic structure. Among the above, X is preferably -O- or -S-, and particularly preferably -O-. When X is -O-, the polymer of the cyclopolymerizable compound, and therefore the sealing material, are more likely to exhibit flexibility. In addition, the O atom is hydrogen-bonded with a group on the surface of the substrate, and the strength of the sealing material is more likely to be increased.

Specific examples of the cyclopolymerizable compound represented by the above general formula (1) include α-allyloxymethylacrylic acid, methyl α-allyloxymethylacrylate, ethyl α-allyloxymethylacrylate, n-propyl α-allyloxymethylacrylate, i-propyl α-allyloxymethylacrylate, n-butyl α-allyloxymethylacrylate, s-butyl α-allyloxymethylacrylate, t-butyl α-allyloxymethylacrylate, n-amyl α-allyloxymethylacrylate, and α-allyloxymethylacrylate. s-Amyl allyloxymethyl acrylate, t-Amyl α-Allyloxymethyl acrylate, n-Hexyl α-Allyloxymethyl acrylate, s-Hexyl α-Allyloxymethyl acrylate, n-Heptyl α-Allyloxymethyl acrylate, n-Octyl α-Allyloxymethyl acrylate, s-Octyl α-Allyloxymethyl acrylate, t-Octyl α-Allyloxymethyl acrylate, 2-Ethylhexyl α-Allyloxymethyl acrylate, Capryl α-Allyloxymethyl acrylate allyl, nonyl α-allyloxymethylacrylate, decyl α-allyloxymethylacrylate, undecyl α-allyloxymethylacrylate, lauryl α-allyloxymethylacrylate, tridecyl α-allyloxymethylacrylate, myristyl α-allyloxymethylacrylate, pentadecyl α-allyloxymethylacrylate, cetyl α-allyloxymethylacrylate, heptadecyl α-allyloxymethylacrylate, stearyl α-allyloxymethylacrylate, nonadecyl α-allyloxymethylacrylate, eicosyl α-allyloxymethylacrylate, ceryl α-allyloxymethylacrylate, melissyl α-allyloxymethylacrylate, methoxyethyl α-allyloxymethylacrylate, methoxyethoxyethyl α-allyloxymethylacrylate, methoxyethoxyethoxyethyl α-allyloxymethylacrylate, 3-methoxybutyl α-allyloxymethylacrylate, ethoxyethyl α-allyloxymethylacrylate, ethoxyethoxyethyl acrylate, phenoxyethyl α-allyloxymethylacrylate, phenoxyethoxyethyl α-allyloxymethylacrylate, hydroxyethyl α-allyloxymethylacrylate, hydroxypropyl α-allyloxymethylacrylate, hydroxybutyl α-allyloxymethylacrylate, fluoroethyl α-allyloxymethylacrylate, difluoroethyl α-allyloxymethylacrylate, chloroethyl α-allyloxymethylacrylate, dichloroethyl α-allyloxymethylacrylate, bromoethyl α-allyloxymethylacrylate, dibromoethyl α-allyloxymethylacrylate, vinyl α-allyloxymethylacrylate, allyl α-allyloxymethylacrylate, methallyl α-allyloxymethylacrylate, crotyl α-allyloxymethylacrylate, propargyl α-allyloxymethylacrylate, cyclopentyl α-allyloxymethylacrylate, cyclohexyl α-allyloxymethylacrylate, α-allyloyoxymethylacrylate, 4-methylcyclohexyl α-allyloxymethylacrylate, 4-t-butylcyclohexyl α-allyloxymethylacrylate, tricyclodecanyl α-allyloxymethylacrylate, isobornyl α-allyloxymethylacrylate, adamantyl α-allyloxymethylacrylate, dicyclopentadienyl α-allyloxymethylacrylate, phenyl α-allyloxymethylacrylate, methylphenyl α-allyloxymethylacrylate, dimethylphenyl α-allyloxymethylacrylate, trimethylphenyl α-allyloxymethylacrylate, 4-t-butylphenyl α-allyloxymethylacrylate, benzyl α-allyloxymethylacrylate, diphenylmethyl α-allyloxymethylacrylate, diphenylethyl α-allyloxymethylacrylate, triphenylmethyl α-allyloxymethylacrylate, cinnamyl α-allyloxymethylacrylate, naphthyl α-allyloxymethylacrylate, anthranyl α-allyloxymethylacrylate, and the like.

Among the above, α-allyloxymethylacrylic acid is preferred.

The amount of the cyclic polymerizable compound is preferably 1% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 27% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less, based on the total amount of the curable compound. If the viscosity of the liquid crystal sealant is excessively low, when the uncured liquid crystal sealant (frame-shaped sealing pattern) and the liquid crystal material are sandwiched between a pair of substrates and bonded together, 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 "internal collision" in this specification). On the other hand, if the amount of the cyclic polymerizable compound is 30% by mass or less based on the total amount of the curable compound, the viscosity of the liquid crystal sealant is more likely to fall within the desired range, and the internal collision is less likely to occur when the liquid crystal display panel is manufactured. On the other hand, if the amount of the cyclic polymerizable compound is 1% by mass or more based on the total amount of the curable compound, the adhesive strength of the resulting sealant is more likely to be increased, and low moisture permeability is more likely to be achieved.

In addition, when the liquid crystal sealant contains a filler as described below, the amount of the cyclopolymerizable material is preferably 3% by mass or more and 300% by mass or less, more preferably 25% by mass or more and 200% by mass or less, and even more preferably 50% by mass or more and 150% by mass or less, relative to the total amount of the filler. When the ratio of the cyclopolymerizable compound to the filler is within this range, the viscosity of the liquid crystal sealant is more likely to fall within the desired range, and the coatability of the liquid crystal sealant is more likely to be improved.

(2) Other curable compounds Examples of curable compounds other than the above-mentioned cyclopolymerizable compounds that are included in the curable compounds include epoxy compounds having one or more epoxy groups in the molecule, (meth)acrylic compounds having one or more (meth)acryloyl groups in the molecule, and (meth)acrylic-modified epoxy compounds having (meth)acryloyl groups and epoxy groups in the molecule.In this specification, (meth)acryloyl groups refer to methacryloyl groups, acryloyl groups, and both.In addition, (meth)acrylic refers to methacrylic, acrylic, and both, and (meth)acrylate refers to methacrylate, acrylate, and both.

Epoxy Compound In this specification, the epoxy compound refers to a compound having one or more epoxy groups in the molecule. However, in this specification, the epoxy compound does not include a compound having an epoxy group and a (meth)acryloyl group. The curable compound may contain only one type of epoxy compound, or may contain two or more types.

The number of epoxy groups contained in one molecule of the epoxy compound may be one or more. When the curable compound contains an epoxy compound, the thermosetting properties of the liquid crystal sealant tend to be good. Examples of epoxy compounds include 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 realizing low moisture permeability of the resulting sealant.

Examples of aromatic epoxy compounds include aromatic diols such as bisphenol A, bisphenol S, bisphenol F, and bisphenol AD, and diols obtained by modifying these aromatic diols with ethylene glycol, propylene glycol, alkylene glycol, etc., and aromatic polyhydric glycidyl ether compounds obtained by reacting epichlorohydrin with them; novolac resins derived from phenol or cresol and formaldehyde, novolac-type polyhydric glycidyl ether compounds obtained by reacting polyphenols such as polyalkenylphenols and their copolymers, and epichlorohydrin; glycidyl ether compounds of xylylene phenol resins, etc.

Among these, cresol novolac type epoxy compounds, phenol novolac type epoxy compounds, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, triphenol methane type epoxy compounds, triphenol ethane type epoxy compounds, trisphenol type epoxy compounds, dicyclopentadiene type epoxy compounds, diphenyl ether type epoxy compounds, and biphenyl type epoxy compounds are preferred.

Here, the epoxy-based compound may be liquid or solid. From the viewpoint of making it easier to achieve low moisture permeability for the sealing material, a solid epoxy-based compound is preferred. The softening point of a solid epoxy-based compound is preferably 40°C or higher and 150°C or lower. The softening point can be measured by the ring and ball method specified in JIS K7234.

The weight average molecular weight of the epoxy compound is preferably 500 to 10,000, and more preferably 1,000 to 5,000. The weight average molecular weight of the epoxy compound is measured in polystyrene equivalent terms by gel permeation chromatography (GPC).

The total amount of epoxy-based compounds 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 curable compounds. If the amount of epoxy-based compounds is 5% by mass or more, the moisture permeability of the encapsulant tends to be further reduced. On the other hand, if the amount of epoxy-based compounds is 60% by mass or less, the amount of the above-mentioned cyclopolymerizable compounds and the like becomes relatively large, which tends to further improve the photopolymerization of the resulting encapsulant and further increase the adhesive strength, etc.

(Meth)acrylic compound In this specification, the (meth)acrylic compound is a compound having one or more (meth)acryloyl groups in the molecule. However, in this specification, the (meth)acrylic compound does not include the above-mentioned cyclopolymerizable compound or a compound having a (meth)acryloyl group and an epoxy group. The curable compound may contain only one type of (meth)acrylic compound, or may contain two or more types.

The number of (meth)acryloyl groups contained in one molecule of a (meth)acrylic compound may be one or more. Examples of (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, 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 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 tri(meth)acrylate; trimethylolpropane tri(meth)acrylate or its oligomer; pentaerythritol tri(meth)acrylate or its oligomer; poly(meth)acrylate of dipentaerythritol; tris(acryloxyethyl)isocyanurate; caprolactone-modified tris(acryloxyethyl)isocyanurate; caprolactone-modified tris(methacryloxyethyl)isocyanurate; poly(alkyl-modified dipentaerythritol meth)acrylates; poly(meth)acrylates of caprolactone-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; and oligo(meth)acrylates of neopentyl glycol, trimethylolpropane, and pentaerythritol. Among these, di(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 (bisphenol A or F type epoxy (meth)acrylates) are preferred.

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

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

Here, the total amount of (meth)acrylic compounds 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 curable compounds. When the total amount of (meth)acrylic compounds is 3% by mass or more, the photocurability of the liquid crystal sealant is likely to be good. On the other hand, when the total amount of (meth)acrylic compounds is 60% by mass or less, the amount of the above-mentioned cyclopolymerizable compounds and epoxy compounds becomes relatively sufficient, and the adhesive strength and low moisture permeability of the resulting sealant are likely to be even better.

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

The number of epoxy groups and (meth)acryloyl groups in the (meth)acrylic-modified epoxy compound is not particularly limited, and each may be only one, or may be two or more. The (meth)acrylic-modified epoxy compound has good compatibility with the above-mentioned cyclopolymerizable compound, the above-mentioned epoxy-based compound, and the above-mentioned acrylic-based compound. Therefore, when the (meth)acrylic-modified epoxy compound is contained as a curable compound, the compatibility between different types of curable compounds becomes very good.

The (meth)acrylic modified epoxy compound is obtained by modifying at least one of the epoxy groups of a bifunctional or higher functional epoxy compound with a (meth)acryloyl group. The (meth)acrylic modified epoxy compound is obtained, for example, by reacting a bifunctional or higher functional epoxy compound with (meth)acrylic acid in the presence of a basic catalyst.

The epoxy compound modified with a (meth)acryloyl group may be a polyfunctional epoxy compound having two or more epoxy groups in the molecule, and from the viewpoint of preventing excessive decrease in adhesive strength of the sealing material due to excessive increase in crosslink density, a bifunctional epoxy compound is preferred. Examples of bifunctional epoxy compounds include bisphenol type epoxy compounds (bisphenol A type, bisphenol F type, 2,2'-diallyl bisphenol A type, bisphenol AD type, hydrogenated bisphenol type, etc.), biphenyl type epoxy compounds, and naphthalene type epoxy compounds. Among them, bisphenol type epoxy compounds of bisphenol A type and bisphenol F type are preferred from the viewpoint of improving the applicability of the liquid crystal sealant. A (meth)acrylic modified epoxy compound derived from a bisphenol type epoxy compound has an advantage of being superior in applicability compared to a (meth)acrylic modified epoxy compound derived from a biphenyl ether type epoxy compound.

In the (meth)acrylic modified epoxy compound, the ratio of the number of moles of (meth)acryloyl groups to the number of moles of epoxy groups is preferably 1 or more, and more preferably 2 or more. By increasing the ratio of the number of moles of (meth)acryloyl groups, it becomes easier to suppress the elution of the liquid crystal sealant into the liquid crystal.

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

The amount of the (meth)acrylic-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, based on the total amount of the curable composition. When the amount of the (meth)acrylic-modified epoxy compound is 10% by mass or more, it is easy to increase the compatibility between the above-mentioned cyclopolymerizable compound or acrylic compound and the epoxy compound. On the other hand, when the amount of the (meth)acrylic-modified epoxy compound is 80% by mass or less, the amount of the cyclopolymerizable compound etc. is likely to be sufficient, and it is even easier to achieve low moisture permeability and high adhesive strength in the resulting sealing material.

Others The curable compound may further contain curable compounds other than those described above, as long as the object and effects of the present invention are not impaired.
Here, the total amount of the curable composition is preferably 40% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 80% by mass or less, based on the total amount of the liquid crystal sealant. When the total amount of the curable composition is 40% by mass or more, the sealant can easily suppress leakage of liquid crystal in the liquid crystal display panel. On the other hand, when the total amount of the curable composition is 90% by mass or less, the amount of the curing agent described below becomes sufficient, which makes it easier to further improve the curability of the liquid crystal sealant and adjust the viscosity of the liquid crystal sealant to a desired range.

1-2. Hardener The liquid crystal sealant contains a hardener. Examples of the hardener include a heat hardener for hardening the liquid crystal sealant by heat, and a photopolymerization initiator for hardening the liquid crystal sealant by light.

(1) Heat Curing Agent The heat curing agent is not particularly limited as long as it is a material capable of thermally curing the above-mentioned epoxy-based compound or (meth)acrylic-modified epoxy compound, but it is preferable that the heat curing agent is a latent heat curing agent. A latent heat curing agent is a compound that does not cure epoxy-based compounds or (meth)acrylic-modified epoxy compounds under normal storage conditions (room temperature, visible light, etc.), but cures these compounds by heating. The latent heat curing agent is preferably a curing agent (hereinafter also referred to as an "epoxy curing agent") that can open the epoxy group of the above-mentioned curable compound to cure it.

The melting point of the epoxy hardener is preferably 50 to 250°C, more preferably 100 to 200°C, and even more preferably 150 to 200°C, from the viewpoint of increasing the viscosity stability of the liquid crystal sealant and not impairing the moisture resistance of the resulting sealing material.

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

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

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

Amine adduct heat-latent curing agents are heat-latent curing agents consisting of an addition compound obtained by reacting an amine compound having catalytic activity with any compound. Commercially available examples of amine adduct 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 Fine-Techno Co., Ltd.).

Polyamine-based thermal latent hardeners are thermal latent hardeners with a polymer structure obtained by reacting amines with epoxy resins, and examples of commercially available products include ADEKA HARDENER EH4339S and ADEKA HARDENER EH4357S (both manufactured by ADEKA Corporation).

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

The amount of the heat curing agent is preferably 3% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less, based on the total amount of the liquid crystal sealant.

(2) Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is a compound for initiating the curing (polymerization) of the above-mentioned cyclopolymerizable compound, acrylic compound, and further (meth)acrylic modified epoxy compound. The photopolymerization initiator may be a self-cleavage type photopolymerization initiator or a hydrogen-withdrawing inorganic type photopolymerization initiator. The liquid crystal sealing material may contain only one type of photopolymerization initiator, or may contain two or more types.

Examples of self-cleaving photopolymerization initiators include alkylphenone compounds (e.g., benzyl dimethyl ketal compounds such as 2,2-dimethoxy-1,2-diphenylethan-1-one (BASF, IRGACURE 651); α-amino alkylphenone compounds such as 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one (BASF, IRGACURE 907); 1-hydroxy-cyclohexyl-phenyl-ketone (BASF, IRGACURE 907); α-hydroxyalkylphenone compounds such as α-hydroxyalkylphenylphosphine oxide; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoindiphenylphosphine oxide; titanocene compounds such as bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-(4-methylphenylphosphine oxide, etc.); acetophenone-based compounds such as 4-(2-hydroxypropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(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; phenyl glyoxylate-based compounds such as methylphenyl glyoxylate, for example These include benzoin ether compounds such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; and oxime ester compounds such as 1,2-octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] (manufactured by BASF, IRGACURE OXE01) and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) (manufactured by BASF, IRGACURE OXE02).

Examples of hydrogen abstraction type photopolymerization initiators include benzophenone compounds such as benzophenone, o-benzoyl methylbenzoate-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone, 2-chlorothioxanthone (Tokyo Chemical Industry Co., Ltd.), 1-chloro-4-propoxythioxanthone, 1-chloro-4-ethoxythioxanthone (Lambson Limited, Speedcure CPTX), and 2-isopropylxanthone (Lambson Limited, Speedcure CPTX). Thioxanthone compounds such as thioxanthone, 4-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone (manufactured by Lambson Limited, Speedcure DETX), and 2,4-dichlorothioxanthone; anthraquinone compounds such as 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), and 2-hydroxymethylanthraquinone (manufactured by Junsei Chemical Co., Ltd., 2-(hydroxymethyl)anthraquinone); and benzyl compounds.

The absorption wavelength of the photopolymerization initiator is not particularly limited, and it is preferable that the photopolymerization initiator absorbs light with a wavelength of 360 nm or more, for example. In particular, it is more preferable that the photopolymerization initiator absorbs light in the visible light region, and it is particularly preferable that the photopolymerization initiator absorbs light with a wavelength of 360 to 430 nm. When the photopolymerization initiator has an absorption wavelength in this range, it becomes possible to cure the liquid crystal sealant by irradiating it with visible light, and the effect on the liquid crystal material, etc. can be greatly reduced. In this specification, the "visible light region" refers to the wavelength range of 360 nm to 780 nm.

Examples of photopolymerization initiators that absorb light with wavelengths of 360 nm or more include alkylphenone compounds, acylphosphine oxide photopolymerization initiators, titanocene photopolymerization initiators, oxime ester photopolymerization initiators, thioxanthone photopolymerization initiators, and anthraquinone photopolymerization initiators, with oxime ester photopolymerization initiators, thioxanthone photopolymerization initiators, and anthraquinone photopolymerization initiators being preferred, and oxime ester photopolymerization initiators being particularly preferred.

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 or IR measurements.

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 less likely to dissolve into the liquid crystal material when the liquid crystal sealant comes into contact with the liquid crystal material. On the other hand, if the molecular weight is 5000 or less, the compatibility between the photopolymerization initiator and the curable compound increases, and the photocurability of the liquid crystal sealant tends to be good. The molecular weight of the photopolymerization initiator is more preferably 230 or more and 3000 or less, and even more preferably 230 or more and 1500 or less.

The molecular weight of a 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).

Specifically, a sample solution is prepared by dissolving a photopolymerization initiator in THF (tetrahydrofuran), and high performance liquid chromatography (HPLC) measurements are performed. The area percentage of the detected peaks (ratio to the total area of each peak) is then calculated to confirm the presence or absence of a main peak. The main peak is the peak with the greatest intensity (the peak with the highest height) among all peaks detected at a detection wavelength characteristic of each compound (for example, 400 nm for thioxanthone compounds). The relative molecular mass corresponding to the apex of the detected main peak can be measured by liquid chromatography mass spectrometry (LC/MS).

The amount of photopolymerization initiator is preferably 0.01 to 10% by mass relative to the total amount of compounds having an unsaturated double bond in the curable compound (for example, the total amount of the above-mentioned cyclopolymerizable compounds, (meth)acrylic compounds, and (meth)acrylic-modified epoxy compounds). When the amount of photopolymerization initiator is 0.01% by mass or more relative to the total amount of compounds having an unsaturated double bond, the photocurability of the liquid crystal sealant tends to be good. On the other hand, when the content of photopolymerization initiator is 10% by mass or less, the photopolymerization initiator is less likely to dissolve into the liquid crystal. The content of photopolymerization initiator is more preferably 0.1 to 5% by mass relative to the total amount of compounds having an unsaturated double bond in the curable compound, even more preferably 0.1 to 3% by mass, and particularly preferably 0.1 to 2.5% by mass.

1-3. Filler The liquid crystal sealant preferably contains a filler. When the liquid crystal sealant contains a filler, the viscosity of the liquid crystal sealant is more likely to fall within the desired range. In addition, the moisture permeability of the resulting sealant is further reduced. Examples of the filler include inorganic fillers and core-shell type fine particles.

(1) Inorganic Filler The inorganic filler not only imparts a predetermined hardness and linear expansion property to the resulting encapsulant, but also serves to further increase the low moisture permeability of the encapsulant.

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

The shape of the inorganic filler may be regular, such as spherical, plate-like, or needle-like, or may be irregular. When the inorganic filler is spherical, the average primary particle size of the inorganic filler is preferably 1.5 μm or less. 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 BET method described in JIS Z8830 (2013).

The amount of 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 even more 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 inorganic filler, the lower the moisture permeability of the resulting sealant is likely to be, but if the content is too high, the flexibility of the sealant may be impaired. Therefore, the above range is preferable.

(2) Core-shell type microparticles Core-shell type microparticles are microparticles having a core having desired physical properties and a shell portion covering the core. The shell portion can enhance compatibility with other components or cause partial reaction with other components.

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

Another example of the core-shell type microparticles includes microparticles having a core made of an inorganic particle and a shell portion made of a polymer layer covering the core, and having a functional group containing a carbon-carbon double bond on the surface. Examples of the functional group containing a carbon-carbon double bond that the core-shell type microparticles have include vinyl groups, allyl groups, acrylic groups, and methacrylic groups. Examples of the core in the core-shell type microparticles include particles similar to the inorganic fillers described above. Among these, silica particles are preferable from the viewpoint of excellent thermal stability.

The amount of the core-shell type microparticles 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 even more preferably 5% by mass or more and 20% by mass or less, relative to the elemental amount of the curable compound. When the content of the core-shell type microparticles is within this range, it becomes easier to adjust the physical properties of the resulting sealing material to the desired range.

(3) Others Fillers other than those described above may be contained within the scope not impairing the object and effect of the present invention. For example, organic fine particles not having a core-shell structure may be further contained.

As described above, when the amount of the filler and the amount of the cyclopolymerizable compound satisfy a predetermined relationship, the physical properties such as the viscosity of the liquid crystal sealant tend to fall within the desired range, the liquid crystal sealant has good applicability, and internal collisions are less likely to occur when producing a liquid crystal display panel. Here, the total amount of the filler is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less, relative to the total amount of the liquid crystal sealant. When the total amount of the filler is within the above range, it becomes easier to adjust the various physical properties of the liquid crystal sealant to the desired range.

1-4. Others The liquid crystal sealing material may further contain, in addition to the above-mentioned components, a thermal radical generator, organic fine particles, 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 sensitizer, a plasticizer, and a defoaming agent.

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

Examples of silane coupling agents include vinyltrimethoxysilane, gamma-(meth)acryloxypropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and gamma-glycidoxypropyltriethoxysilane.

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

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

The total amount of the other components is preferably 0.1% by mass or more and 50% by mass or less, based on the total amount of the liquid crystal sealant. If the total amount is 50% by 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 as measured by an E-type viscometer is preferably 200 to 450 Pa·s, more preferably 300 to 400 Pa·s. When the viscosity is within the above range, the applicability of the sealant using a dispenser is improved. Furthermore, when the viscosity of the liquid crystal sealant is within this range, the above-mentioned internal collision is even less likely to occur.

2. Liquid crystal display panel and manufacturing method thereof The liquid crystal display panel of the present invention includes a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, and a frame-shaped sealant disposed between the pair of substrates for sealing the liquid crystal layer.

One of the pair of substrates is a display substrate and the other is an opposing substrate. Both of these are transparent substrates. The material of the transparent substrate may be an inorganic material such as glass, or a plastic such as polycarbonate, polyethylene terephthalate, polyethersulfone, and PMMA.

On the surfaces of the pair of substrates (display substrate and counter substrate 9), a matrix of TFTs, a color filter, a black matrix, etc. may be arranged. An alignment film is usually also arranged on the surfaces of the display substrate and counter substrate. The alignment film is a film containing a known organic alignment agent or inorganic alignment agent.

The liquid crystal layer is a layer made of a liquid crystal material sealed within an area surrounded by a pair of substrates and a sealing material. 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 for sealing the liquid crystal. The sealing material is a hardened product of the liquid crystal sealant.

The above liquid crystal display panel is manufactured using the liquid crystal sealant of the present invention. Liquid crystal display panel manufacturing methods generally include the liquid crystal dropping method and the liquid crystal injection method, but the liquid crystal display panel of the present invention is preferably manufactured by the liquid crystal dropping method.

The manufacturing method for liquid crystal display panels using the liquid crystal dropping method is as follows:
1) providing a pair of substrates;
2) forming a frame-shaped sealing pattern on one of the pair of substrates using the liquid crystal sealant;
3) applying a dummy sealant to the outside of the frame-shaped sealing pattern to form a dummy seal pattern;
4) dropping a liquid crystal material onto an area surrounded by the frame-shaped sealing pattern on one of the substrates and/or onto a corresponding area on the other substrate while the frame-shaped sealing pattern and the dummy seal pattern are in an uncured state;
5) laminating one substrate and the other substrate with a liquid crystal material interposed therebetween under a reduced pressure atmosphere;
6) curing the frame-shaped sealing pattern and the dummy seal pattern;
Includes.
Either step 2) or step 3) may be carried out first. After step 6), a step of removing the region where the dummy seal pattern is formed may be further carried out.

In step 1, a display substrate and an opposing substrate are typically prepared, on which a matrix of TFTs, a color filter, a black matrix, and an alignment film are arranged.

In step 2), the area to which the liquid crystal sealant is applied is appropriately selected depending on the structure of the liquid crystal display panel. The method of applying the liquid crystal sealant is not particularly limited as long as it is possible to apply the liquid crystal sealant to the desired width, but it can be applied, for example, by a dispenser.

In step 3, the area to which the dummy sealant is applied is also selected appropriately according to the structure of the liquid crystal display panel. The dummy sealant may be the same as the liquid crystal sealant, or it may be different. When the dummy sealant and the liquid crystal sealant are different, the composition of the dummy sealant is not particularly limited and is the same as that of known dummy sealants. The dummy sealant can also be applied using a dispenser or the like.

Here, the dummy seal pattern is positioned with a gap between it and the sealing pattern. By forming this dummy seal pattern, when the pair of substrates are superimposed in step 5) described below, a reduced pressure space is formed between the dummy seal and the sealing material. This allows the pair of substrates to be firmly fixed together.

In step 4), the liquid crystal material is dropped into a predetermined area. Here, the uncured state of the frame-shaped sealing pattern and the dummy sealing pattern means that the curing reaction of the liquid crystal sealant and the dummy sealant has not progressed to the gel point. For this reason, in step 4), the frame-shaped sealing pattern may be irradiated with light or heated in advance to semi-cure it in order to suppress dissolution of the liquid crystal sealant into the liquid crystal. In addition, when the liquid crystal is dropped onto the other substrate in step 4), the liquid crystal is dropped so that it fits inside the frame-shaped sealing pattern when the two substrates with alignment films are superimposed in step 5).

In step 5), one substrate and the other substrate are superimposed with the liquid crystal material interposed therebetween under a reduced pressure atmosphere. By superimposing the liquid crystal material under a reduced pressure atmosphere in this manner, a reduced pressure state is created between the resulting sealant and the dummy seal, as described above. However, when the pair of substrates are superimposed in step 5), the frame-shaped sealing pattern is uncured. Therefore, when a general liquid crystal sealant is used, the liquid crystal material may get into the frame-shaped sealing pattern (internal collision may occur). In contrast, with the liquid crystal sealant described above, such internal collision is less likely to occur. Furthermore, in particular, when the liquid crystal sealant contains a filler, internal collision is even less likely to occur.

In step 6), curing by light irradiation and then 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, which makes it possible to suppress dissolution of the liquid crystal sealant 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.

The light to be irradiated is selected appropriately depending on the type of photopolymerization initiator in the above-mentioned liquid crystal sealant (and dummy sealant), but light in the visible light region is preferred, for example light with a wavelength of 370 nm or more and 450 nm or less. This is because light of the above wavelengths causes relatively little damage to the liquid crystal material and driving electrodes. For the light irradiation, known light sources that emit ultraviolet light or visible light can be used. When irradiating visible light, high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, xenon lamps, fluorescent lamps, etc. can be used.

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

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

The present invention will be described below with reference to examples. The scope of the present invention should not be construed as being limited by the examples.

1. Preparation of Materials The following compounds were prepared as materials to be used in the Examples and Comparative Examples.

(1) Curable compound (cyclization polymerizable compound)
Curable compound (A-1): Cyclopolymerizable compound represented by the following general formula (1A) (trade name "AOMA", manufactured by Nippon Shokubai Co., Ltd.)

　・硬化性化合物（Ａ－４）：下記式で表されるエトキシ化ビスフェノールＡジアクリレート（新中村化学工業社製、Ａ－ＢＰＥ－４）

　（式中、ｍ＋ｎ＝４）
　・硬化性化合物（Ａ－５）：ビスフェノールＦ型エポキシ樹脂（三菱ケミカル社製、ＹＬ９８３Ｕ）
　・硬化性化合物（Ａ－６）：アクリル変性エポキシ樹脂（ＫＳＭ社製、ＢＡＥＭ－５０） (Other curable compounds)
Curable compound (A-2): Bisphenol A diacrylate ester (manufactured by Daicel Allnex Corporation, Ebecryl 3700)
Curable compound (A-3): Tris-(2-acryloxyethyl)isocyanurate represented by the following formula (A-9300-2CL, manufactured by Shin-Nakamura Chemical Co., Ltd.)

Curable compound (A-4): Ethoxylated bisphenol A diacrylate represented by the following formula (A-BPE-4, manufactured by Shin-Nakamura Chemical Co., Ltd.)

(In the formula, 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 (BAEM-50, manufactured by KSM)

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

(3) Filler: Silica particles (manufactured by Admatechs Co., Ltd., SO-C1)
・Core-shell type microparticles (Aica Kogyo Co., Ltd., 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 the curable compound (A-1), 70 parts by mass of the curable compound (A-2), 100 parts by mass of the curable compound (A-5), 400 parts by mass of the curable compound (A-6), 130 parts by mass of a heat curing agent, 10 parts by mass of a photopolymerization initiator, 100 parts by mass of silica particles, 100 parts by mass of core-shell type fine particles, and 10 parts by mass of a silane coupling agent were mixed using a triple roll to obtain a liquid crystal sealing material.

(Examples 2 to 9 and Comparative Examples 1 and 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 liquid crystal sealant was evaluated for adhesive strength, moisture permeability (low moisture permeability), internal impact resistance, and drawability by the following methods. The results are shown in Table 1.

(Adhesive strength)
The obtained liquid crystal sealant was used with a dispenser (Shot Master, manufactured by Musashi Engineering Co., Ltd.) to form a 38 mm x 38 mm square frame-shaped sealing pattern (cross-sectional area ²⁵⁰⁰ μm2) on a 40 mm x 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC Co., Ltd.) on which a transparent electrode and an alignment film had been previously formed.
Next, a pair of glass substrates was bonded to the glass substrate on which the frame-shaped sealing pattern was formed perpendicularly under reduced pressure, and then the pair of glass substrates was exposed to the atmosphere and bonded together. The two bonded glass substrates were then held in a light-shielding box for one minute, and then irradiated with light containing 3000 mJ/ ^cm2 visible light (light with a wavelength of 370 to 450 nm), and further heated at 120°C for one hour to harden the frame-shaped sealing pattern, thereby obtaining a test piece.
The corner of the frame-shaped sealing pattern of the obtained test piece was pressed vertically at a speed of 5 mm/min using a pressing tester (Model 210, manufactured by Intesco Co., Ltd.). This operation was performed on 10 glass substrates (n=10), and the number of glass substrates that were broken was counted. The adhesive strength was evaluated according to the following criteria.
◎: 10 glass substrates were broken. ○: 6 to 9 glass substrates were broken. △: 1 to 5 glass substrates were broken. ×: 0 glass substrates were broken. The more glass substrates were broken, the higher the adhesive strength was judged to be. If the glass substrate was △ or better, it was at a level that did not pose a problem in practical use and was 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 purged with nitrogen for 5 minutes, after which it was irradiated with light of 3000 mJ/cm ² (light calibrated with a 365 nm wavelength sensor) and further heated at 120° C. for 1 hour to produce a cured film.

Two sheets of cured film were placed on an aluminum cup containing calcium chloride (anhydrous) as a moisture absorbent, and an aluminum ring was placed on top and screwed, after which the initial weight of the entire aluminum cup was measured. The aluminum cup was then placed in a thermostatic chamber set at 60°C and 90% Rh, and after 24 hours had passed, the aluminum cup was taken out and its weight was measured. The obtained weight value was substituted into the following formula to calculate the moisture permeability.
Formula:
Moisture permeability=(weight after test−weight before test)×film thickness/(film area×100)
And the evaluation was based on the following criteria:
⊚: Moisture permeability of 60 g/ ^m2 or less ◯: Moisture permeability of more than 60 g/ ^m2 and less than 80 g/ ^m2 △: Moisture permeability of more than 80 g/ ^m2 and less than 100 g/ ^m2 ×: Moisture permeability of more than 100 g/ ^m2 If it was △ or above, it was at a level that did not cause any problems in practical use and was judged to be good.

(Internal shock resistance)
The obtained liquid crystal sealant was used with a dispenser (Shot Master, manufactured by Musashi Engineering Co., Ltd.) to form a rectangular frame-shaped sealing pattern (cross-sectional area 2500 μm ² ) measuring 24 mm × 24 mm and a line width of 0.5 mm on a 40 mm × 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC Co., Ltd.) on which a transparent electrode and an alignment film had been previously formed. Furthermore, a rectangular frame-shaped dummy seal pattern measuring 38 mm × 38 mm and a line width of 1 mm was formed around the periphery of the pattern using the liquid crystal sealant. Next, a minute droplet (drop amount 2.0 μl) of liquid crystal (MLC-3007; manufactured by Merck) was dropped into the frame of the frame-shaped sealing pattern.
Next, the pair of glass substrates were bonded together under reduced pressure so as to be perpendicular to the glass substrate on which the frame-shaped sealing pattern and the dummy seal pattern were formed, and then the substrates were exposed to the atmosphere and bonded together. The two bonded glass substrates were then held in a light-shielding box for one minute, and then irradiated with light (light with a wavelength of 370 to 450 nm) containing 3000 mJ/ ^cm2 of visible light, and further heated at 120°C for one hour to harden the seal, thereby obtaining a test piece. The interface between the sealant and the liquid crystal was then observed with a polarizing microscope, and evaluated according to the following criteria. The results are shown in Table 1.
◎: The penetration (sealing path) of the liquid crystal material in the width direction of the liquid crystal sealant (cured product) is 0.1 mm or less. ◯: The seal path is more than 0.1 mm and less than 0.3 mm. △: The seal path is more than 0.3 mm and less than 0.5 mm. ×: The seal path is more than 0.5 mm.

(Drawability)
The obtained liquid crystal sealant was filled into a 10 cc syringe, degassed, and then filled into a dispenser (Shot Master: manufactured by Musashi Engineering Co., Ltd.). Using this dispenser, the liquid crystal sealant was applied to a glass substrate at a speed of 4 cm per second to perform drawing. The drawing property (applicability) was evaluated according to the following criteria.
○: No breaks or thinning points △: No breaks, but one or more thinning points ×: One or more breaks

As shown in Table 1 above, when the liquid crystal sealant contains the cyclopolymerizable compound (curable compound (A-1)) represented by the above general formula (1), the internal impact resistance and drawing properties are good, and furthermore, the adhesive strength of the resulting sealant is high and the moisture permeability is low (Examples 1 to 9). The polymer structure of the above cyclopolymerizable compound makes it possible to achieve both high adhesive strength and low moisture permeability, which was previously particularly difficult.

In contrast, when curable compounds (A-3) and (A-4) with structures different from the above general formula (1) were used, the results for either adhesive strength or low moisture permeability were poor (Comparative Examples 1 and 2).

In the examples, the internal impact resistance was particularly good when the amount of the cyclopolymerizable compound was 3% by mass or more and 300% by mass or less relative to the total amount of the filler (Examples 1 to 7). It is believed that the viscosity of the liquid crystal sealant was in a moderate range, and the liquid crystal was less likely to enter the frame-shaped sealing pattern when the materials were laminated in a vacuum environment.

This application claims priority from Japanese Patent Application No. 2023-034812, filed March 7, 2023. All contents of that application are incorporated herein by reference.

According to the present invention, there are provided a liquid crystal sealant capable of producing a sealant having adhesive strength and low moisture permeability, a liquid crystal display panel using the same, and a manufacturing method thereof, which are therefore extremely useful in the field of liquid crystal display panel manufacturing.

Claims (15)

A curable compound and a curing agent are included,
The curable compound contains a cyclopolymerizable compound represented by the following general formula (1):
Liquid crystal sealant.

(In the general formula (1),
R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms;
^R2 and ^R3 each independently represent a hydrocarbon group having 1 to 4 carbon atoms;
X represents a single bond, -O-, -S-, or NR ⁴ (R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms). The amount of the cyclopolymerizable compound is 1% by mass or more and 30% by mass or less based on the total amount of the curable compound.
The liquid crystal sealant according to claim 1 . Further comprising a filler,
the amount of the cyclopolymerizable compound is 3% by mass or more and 300% by mass or less based on the total amount of the filler;
The liquid crystal sealant according to claim 1 . The filler includes core-shell type microparticles.
The liquid crystal sealant according to claim 3 . The curable compound further includes an epoxy-based compound having an epoxy group,
The curing agent includes at least one thermal curing agent selected from the group consisting of 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 according to claim 1 . Further comprising a silane coupling agent,
The liquid crystal sealant according to claim 1 . the curing agent contains at least one photopolymerization initiator selected from the group consisting of an oxime ester-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, and an anthraquinone-based photopolymerization initiator;
The liquid crystal sealant according to claim 1 . When the composition is applied to a thickness of 100 μm, irradiated with 3000 mJ/ ^cm2 of light calibrated with a 365 nm wavelength sensor, and heated at 120° C. for 1 hour, the moisture permeability of the cured product is 80 g/ ^m2 or less.
The liquid crystal sealant according to claim 1 . The seal path measured by the following method is 0.5 mm or less.
The liquid crystal sealant according to claim 1 .
(Method of measuring seal path)
(i) On a glass substrate with an alignment film, a frame-shaped sealing pattern of 24 mm×24 mm with a line width of 0.5 mm is formed using the liquid crystal sealant.
(ii) A 38 mm×38 mm dummy seal pattern is formed using the liquid crystal sealant so as to surround the frame-shaped sealing pattern.
(iii) Liquid crystal is dropped into the frame-shaped sealing pattern.
(iv) The glass substrate with the alignment film and an opposing substrate are stacked under reduced pressure so as to sandwich the frame-shaped sealing pattern, and then the stack is opened to the atmosphere to obtain a laminate.
(v) The laminate is kept in a light-shielding box for 1 minute and irradiated with light having a wavelength of 370 nm to 450 nm at 3000 mJ/ ^cm2 .
(vi) The laminate is heated at 120° C. for 1 hour to cure the liquid crystal sealant.
(vii) The boundary between the liquid crystal sealant and the liquid crystal after the hardening is confirmed by a polarizing microscope, and the length of the liquid crystal that has penetrated in the width direction of the liquid crystal sealant after the hardening is defined as the seal path. A pair of substrates;
A liquid crystal layer sandwiched between the pair of substrates;
a frame-shaped sealant disposed between the pair of substrates for sealing the liquid crystal layer;
A liquid crystal display panel having
The sealing material is a cured product of the liquid crystal sealant according to any one of claims 1 to 9.
LCD display panel. Providing a pair of substrates;
A step of applying the liquid crystal sealant according to any one of claims 1 to 9 onto one substrate to form a frame-shaped sealing pattern;
applying a dummy sealant to the outside of the frame-shaped sealing pattern to form a dummy seal pattern;
dropping a liquid crystal material onto the inside of the frame-shaped sealing pattern and/or onto the other substrate while the frame-shaped sealing pattern and the dummy seal pattern are in an uncured state;
a step of overlapping the pair of substrates with the liquid crystal material interposed therebetween under a reduced pressure atmosphere;
hardening the frame-shaped sealing pattern and the dummy seal pattern;
A method for manufacturing a liquid crystal display panel, comprising: In the step of forming the dummy seal pattern, the dummy sealant is the liquid crystal sealant according to any one of claims 1 to 9.
The method for manufacturing the liquid crystal display panel according to claim 11 . In the step of curing the frame-shaped sealing pattern and the dummy seal pattern, light is irradiated.
The method for manufacturing the liquid crystal display panel according to claim 12 . The light includes wavelengths in the visible light range.
The method for manufacturing the liquid crystal display panel according to claim 13 . In the step of hardening the frame-shaped sealing pattern and the dummy seal pattern, heating is further performed.
The method for manufacturing the liquid crystal display panel according to claim 13 .