JP2005195977A - Curing resin composition for liquid crystal display element, sealant for liquid crystal display element, vertical conduction material, and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curing resin composition for a liquid crystal display element the most suitable for the manufacture of the liquid crystal display element especially by a dropping method since liquid crystal contamination is not caused by dissolution of a component of the curing resin composition into a liquid crystal in the manufacture of the liquid crystal display element and thereby color unevenness in liquid crystal display is nearly eliminated, to provide a sealant for the liquid crystal display element using the curing resin composition for the liquid crystal display element, to provide a vertical conduction material, and to provide the liquid crystal display element. <P>SOLUTION: The curing resin composition for the liquid crystal display element contains an episulfide resin and a heat curing agent and further contains a radical polymerizable resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention is particularly suitable for the production of liquid crystal display elements by the dripping method because the components do not dissolve in the liquid crystal and cause liquid crystal contamination in the production of the liquid crystal display elements, and there is little color unevenness in the liquid crystal display. The present invention relates to a curable resin composition for a liquid crystal display element, a sealant for a liquid crystal display element, a vertical conduction material, and a liquid crystal display element.

Conventionally, a liquid crystal display element such as a liquid crystal display cell forms a cell by facing two transparent substrates with electrodes facing each other at a predetermined interval and sealing the periphery with a sealing agent made of a curable resin composition. However, it was produced by injecting liquid crystal into the cell from a liquid crystal injection port provided in a part thereof, and sealing the liquid crystal injection port with a sealing agent or a sealing agent.

In this method, first, a seal pattern in which a liquid crystal injection port using a thermosetting sealant is provided by screen printing on either one of two transparent substrates with electrodes is formed at 60 to 100 ° C.
Pre-bake to dry the solvent in the sealant. Next, alignment is performed with the two substrates facing each other with a spacer interposed therebetween, and the gap in the vicinity of the seal is adjusted by performing hot pressing at 110 to 220 ° C. for 10 to 90 minutes, and then at 110 to 220 ° C. in an oven. 10
Heat for ~ 120 minutes to fully cure the sealant. Next, liquid crystal was injected from the liquid crystal injection port, and finally, the liquid crystal injection port was sealed using a sealing agent to produce a liquid crystal display element.

However, according to this manufacturing method, the positional displacement, gap variation, decrease in adhesion between the sealing agent and the substrate, etc. occur due to thermal strain; residual solvent thermally expands to generate bubbles, resulting in cap variation and seal path. The seal curing time is long; the prebaking process is complicated; the usable time of the sealant is short due to the volatilization of the solvent; and it takes time to inject liquid crystal. In particular, in a large liquid crystal display device in recent years, it takes a very long time to inject liquid crystal.

On the other hand, a manufacturing method of a liquid crystal display element called a dripping method using a photocuring / thermosetting sealant has been studied. In the dropping method, first, a rectangular seal pattern is formed on one of the two transparent substrates with electrodes by screen printing. Next, fine droplets of liquid crystal are dropped and applied to the entire surface of the transparent substrate frame in an uncured state of the sealant, and the other transparent substrate is immediately overlaid, and the seal portion is irradiated with ultraviolet rays for temporary curing. Thereafter, heating is performed at the time of liquid crystal annealing to perform main curing, and a liquid crystal display element is manufactured. If the substrates are bonded together under reduced pressure, a liquid crystal display element can be manufactured with extremely high efficiency. In the future, this dripping method is expected to become the mainstream of liquid crystal display manufacturing methods.

As a sealing agent for a liquid crystal display element used in such a dropping method, an epoxy resin is generally used as a thermosetting component because high adhesiveness is obtained (for example, Patent Document 1). However, in the manufacturing method of the liquid crystal display device by the dripping method, a slight time lag occurs between the start of heating in the main curing process until the epoxy resin is completely cured. The resin and the liquid crystal come into direct contact. At this time, there is a problem that a part of the epoxy resin may flow out into the liquid crystal and become contaminated. When the liquid crystal is contaminated, the alignment of the liquid crystal is disturbed, which may cause display defects such as uneven color.

JP 2001-133794 A

In view of the above-mentioned present situation, the present invention has a liquid crystal display element produced by a dripping method in particular, because in the manufacture of a liquid crystal display element, the components do not dissolve into the liquid crystal and cause liquid crystal contamination, so that there is little color unevenness in the liquid crystal display. An object of the present invention is to provide a curable resin composition for a liquid crystal display element, a sealing agent for a liquid crystal display element, a vertical conduction material, and a liquid crystal display element that are optimal for the production of the above.

The present invention is a curable resin composition for a liquid crystal display element containing an episulfide resin and a thermosetting agent.
The present invention is described in detail below.

As a result of intensive studies, the present inventors can improve the curability and the adhesiveness by using an episulfide resin instead of the epoxy resin. When used as a sealant for the production of a liquid crystal display device, the time for the uncured low molecular weight substance and the liquid crystal to contact each other in the main curing step is extremely short, and it is found that liquid crystal contamination can be suppressed. It came to be completed.

The curable resin composition for a liquid crystal display element of the present invention contains an episulfide resin.
It does not specifically limit as said episulfide resin, What is marketed can be used. Examples of commercially available episulfide resins include bisphenol A type episulfide resins (“YL7000” manufactured by Japan Epoxy Resin Co., Ltd.).
In addition, what was obtained by making commercially available epoxy resin and potassium thiocyanate react can also be used.
In addition, the curable resin composition for a liquid crystal display element of the present invention containing such an episulfide resin may be inferior in storage stability, but in this case, it is preserved by adding an antioxidant, an anti-aging agent, or the like. Stability can be improved. Of these, it is preferable to add phosphites such as diphenyldecyl phosphite.

The curable resin composition for a liquid crystal display element of the present invention preferably further contains a radical polymerizable resin. By containing a radically polymerizable resin, the curable resin composition for a liquid crystal display element of the present invention can be a combined type of photocuring and thermosetting.

Although it does not specifically limit as said radically polymerizable resin, (meth) acrylic resin is suitable, Although it does not specifically limit as said (meth) acrylic resin, It may be epoxy (meth) acrylate or urethane (meth) acrylate. preferable. In this specification, (meth) acrylic acid means acrylic acid or methacrylic acid.

Examples of the epoxy (meth) acrylate include novolac type epoxy resin, bisphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin,
A tris (hydroxyphenyl) alkyl type epoxy resin, a tetrakis (hydroxyphenyl) alkyl type epoxy resin or the like partially or wholly (meth) acrylated is preferred.

The (meth) acrylated product of the epoxy resin can be obtained, for example, by reacting an epoxy resin and (meth) acrylic acid in the presence of a basic catalyst according to a conventional method. It is possible to obtain an epoxy resin having a desired acrylation rate by appropriately changing the blending amount of the epoxy resin and (meth) acrylic acid.

As said urethane (meth) acrylate, it is obtained by the following methods, for example. That is, a method of reacting a polyol with a bifunctional or higher isocyanate and further reacting a (meth) acryl monomer having a hydroxyl group and glycidol; a (meth) acryl having a hydroxyl group in a bifunctional or higher isocyanate without using a polyol It can be produced by a method in which a monomer or glycidol is reacted; a method in which glycidol is reacted with a (meth) acrylate having an isocyanate group. Specifically, for example, first, 1 mol of trimethylolpropane and 3 mol of isophorone diisocyanate are reacted under a tin-based catalyst, and an isocyanate group remaining in the obtained compound and hydroxyethyl acrylate which is an acrylic monomer having a hydroxyl group and It can be produced by reacting with glycidol which is an epoxy having a hydroxyl group.

The blending amount of the episulfide resin in the curable resin of the curable resin composition for a liquid crystal display element of the present invention is not particularly limited, but a preferred lower limit is 5% by weight and a preferred upper limit with respect to the total amount of resin contained. Is 50% by weight. If it is less than 5% by weight, a curing accelerating effect by the episulfide resin cannot be sufficiently obtained, and liquid crystal contamination may not be suppressed,
Adhesiveness may decrease. If it exceeds 50% by weight, the reaction of the episulfide resin is likely to occur, and the storage stability of the sealant that can be obtained may be inferior.

The curable resin composition for a liquid crystal display element of the present invention contains a thermosetting agent.
The thermosetting agent is for reacting and crosslinking an episulfide group or the like in the curable resin composition for liquid crystal display elements by heating, and adhesion of the curable resin composition for liquid crystal display elements after curing, Has the role of improving moisture resistance. As the thermosetting agent, a latent curing agent having a melting point of 100 ° C. or higher is preferably used. When a curing agent having a melting point of 100 ° C. or lower is used, the storage stability may be remarkably deteriorated.

Although it does not specifically limit as said thermosetting agent, It is preferable that it is an amine type or a thiol type from a reactive surface, and it is especially preferable that it is a hydrazide type. Examples of the hydrazide-based thermosetting agent include 1,3-bis [hydrazinocarbonoethyl-5-isopropylhydantoin] and the like.
Further, the thiol-type thermosetting agent is not particularly limited, but a polythiol compound having two or more thiol groups in one molecule is preferable. For example, ethanedithiol, propanedithiol, hexamethylenedithiol, decamethylenedithiol, tolylene-2 Aliphatic polythiols such as 1,4-dithiol; aromatic polythiols such as xylenedithiol; diglycol dimercaptan, triglycol dimercaptan, tetraglycol dimercaptan,
Examples thereof include cyclic sulfide compounds such as thiodiglycol dimercaptan, thiotriglycol dimercaptan, thiotetraglycol dimercaptan, trimethylolpropane tris-β-mercaptopropionate, and a 1,4-dithiane ring-containing polythiol compound. These polythiol compounds may be used independently and 2 or more types may be used together.

Other examples of the thermosetting agent include, for example, dicyandiamide, guanidine derivatives, 1
-Cyanoethyl-2-phenylimidazole, N- [2- (2-methyl-1-imidazolyl) ethyl] urea, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-
Ethyl-s-triazine, N, N′-bis (2-methyl-1-imidazolylethyl) urea, N, N ′-(2-methyl-1-imidazolylethyl) -adipamide, 2-phenyl-
Imidazole derivatives such as 4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole; acids such as modified aliphatic polyamines, tetrahydrophthalic anhydride, ethylene glycol-bis (anhydrotrimellitate) Anhydrous; addition products of various amines and epoxy resins. Even if these are used alone,
Two or more kinds may be used in combination.

As the thermosetting agent, a coating curing agent in which the surface of solid curing agent particles is coated with fine particles is also suitable. If such a coating curing agent is used, a curable resin composition for a liquid crystal display element having high storage stability can be obtained even if a thermosetting agent is blended in advance.

In the curable resin composition for a liquid crystal display element of the present invention, the amount of the thermosetting agent is not particularly limited, but a preferred lower limit is 3 parts by weight with respect to 100 parts by weight of the curable resin contained.
A preferred upper limit is 30 parts by weight. If it is less than 3 parts by weight, the resulting sealant may not be sufficiently cured, and if it exceeds 30 parts by weight, the thermosetting agent may remain, causing problems in long-term reliability. A more preferred lower limit is 5 parts by weight, and a more preferred upper limit is 20 parts by weight.

Moreover, when the curable resin composition for liquid crystal display elements of this invention contains the said radical polymerizable resin, it is preferable to contain a photoinitiator. This is because the curable resin composition for a liquid crystal display element of the present invention can be a combined type of photocuring and thermosetting.

Although it does not specifically limit as said photoinitiator, What has a reactive double bond and a photoreaction start part is suitable. When such a photopolymerization initiator is used, sufficient reactivity can be imparted to the curable resin composition for a liquid crystal display element, and it does not dissolve into the liquid crystal and contaminate the liquid crystal. Of these, benzoin (ether) compounds having a reactive double bond and a hydroxyl group and / or a urethane bond are preferred. The benzoin (ether) compounds represent benzoins and benzoin ethers.

Examples of the reactive double bond include residues such as an allyl group, a vinyl ether group, and a (meth) acryl group, and a (meth) acryl residue is preferable because of its high reactivity. By having such a reactive double bond, the weather resistance of the curable resin composition for a liquid crystal display element of the present invention is improved.

The said benzoin (ether) type compound should just have any one of a hydroxyl group and a urethane bond, and may have both. If the benzoin (ether) compound has neither a hydroxyl group nor a urethane bond, it may elute into the liquid crystal.

In the benzoin (ether) compound, the reactive double bond and the hydroxyl group and / or the urethane bond may be located at any part of the benzoin (ether) skeleton, and are represented by the following general formula (1). Those having a molecular skeleton are preferred. If a compound having such a molecular skeleton is used as a photopolymerization initiator, the residue is reduced and the amount of outgas can be reduced.

式中、Ｒは水素、炭素数４以下の脂肪族炭化水素残鎖を表す。Ｒが炭素数４を超える脂肪
族炭化水素残鎖であると、光重合開始剤を配合したときの保存安定性は増加するものの、
置換基の立体障害により反応性が低下することがある。

In the formula, R represents hydrogen or a residual aliphatic hydrocarbon chain having 4 or less carbon atoms. When R is an aliphatic hydrocarbon residual chain having more than 4 carbon atoms, the storage stability when a photopolymerization initiator is added increases,
The reactivity may decrease due to steric hindrance of the substituent.

Examples of benzoin (ether) compounds having a molecular skeleton represented by general formula (1) include compounds represented by the following general formula (2).

式中、Ｒは水素又は炭素数４以下の脂肪族炭化水素残基を表し、Ｘは炭素数１３以下の２
官能イソシアネート誘導体の残基を表し、Ｙは炭素数４以下の脂肪族炭化水素残基又は残
基を構成する炭素と酸素の原子数比が３以下の残基を表す。Ｘが炭素数１３を超える２官
能イソシアネート誘導体の残基であると、液晶に溶解しやすくなることがあり、Ｙが炭素
数４を超える脂肪族炭化水素基又は炭素と酸素の原子数比が３を超える残基であると、液
晶に溶解しやすくなることがある。

In the formula, R represents hydrogen or an aliphatic hydrocarbon residue having 4 or less carbon atoms, and X represents 2 having 13 or less carbon atoms.
Y represents a residue of a functional isocyanate derivative, and Y represents an aliphatic hydrocarbon residue having 4 or less carbon atoms or a residue having an atomic ratio of carbon to oxygen constituting the residue of 3 or less. When X is a residue of a bifunctional isocyanate derivative having more than 13 carbon atoms, it may be easily dissolved in the liquid crystal, and Y may be an aliphatic hydrocarbon group having more than 4 carbon atoms or an atomic ratio of carbon to oxygen of 3 If the residue exceeds 50, it may be easily dissolved in the liquid crystal.

Other examples of the photopolymerization initiator include benzophenone, 2,2-diethoxyacetophenone, benzyl, benzoyl isopropyl ether, benzyl dimethyl ketal, 1
-Hydroxycyclohexyl phenyl ketone, thioxanthone and the like can be used.
These photoinitiators may be used independently and may use 2 or more types together.

The minimum with the preferable compounding quantity of the said photoinitiator in the curable resin composition for liquid crystal display elements of this invention is 1 weight%, and a preferable upper limit is 10 weight%. If it is less than 1% by weight, the ability to initiate photopolymerization may be insufficient and the curing rate may be slow. Even if it is used in an amount exceeding 10% by weight, there is no improvement in the curing rate. A large amount of the polymerization initiator may remain, and the physical properties of the cured product may be impaired such as deterioration of weather resistance. A more preferable upper limit is 5% by weight, and 3% by weight.
Most preferred is.

The curable resin composition for a liquid crystal display element of the present invention may contain a silane coupling agent. The silane coupling agent mainly has a role as an adhesion aid for improving the adhesion between the curable resin composition for a liquid crystal display element of the present invention and the transparent substrate.
The silane coupling agent is not particularly limited, but is excellent in the effect of improving adhesion to a transparent substrate and the like, and can be prevented from flowing into the liquid crystal material by chemically bonding with a curable resin. -Aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-isocyanatopropyltrimethoxysilane, etc., and the imidazole skeleton and alkoxysilyl group are bonded via a spacer group Those composed of an imidazolesilane compound having the above structure are preferably used. These silane coupling agents may be used alone or in combination of two or more.

The curable resin composition for a liquid crystal display element of the present invention may contain a filler for the purpose of improving the adhesiveness due to the stress dispersion effect and improving the linear expansion coefficient. The filler is not particularly limited,
For example, silica, diatomaceous earth, alumina, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, barium sulfate, gypsum, calcium silicate, talc, glass beads, sericite activity White clay, bentonite,
Examples thereof include inorganic fillers such as aluminum nitride and silicon nitride.

In the curable resin composition for a liquid crystal display element of the present invention, the preferable lower limit of the glass transition temperature after curing is 80 ° C., and the preferable upper limit is 150 ° C. When the liquid crystal display element is produced using the liquid crystal display element sealant of the present invention when the temperature is lower than 80 ° C., the moisture resistance (high temperature and humidity resistance) may be inferior. It may be inferior in adhesion to the substrate.
In addition, the said glass transition temperature is the value measured on conditions with a temperature increase rate of 5 degree-C / min and a frequency of 10 Hz by DMA method. However, since measurement of the glass transition temperature by the DMA method requires a large amount of sample, when only a small amount of sample is obtained, it is preferable to perform the measurement at a temperature increase rate of 10 ° C./min by the DSC method. . In general, the glass transition temperature measured by the DSC method is about 30 ° C. lower than the glass transition temperature measured by the DMA method. Accordingly, when the glass transition temperature is measured by the DSC method, the curable resin composition for a liquid crystal display element of the present invention has a preferred lower limit of 50 ° C. and a preferred upper limit of 120 ° C. for the glass transition temperature after curing. .

The method for producing the curable resin composition for a liquid crystal display element of the present invention is not particularly limited, and examples thereof include a method of mixing the episulfide resin and the thermosetting agent by a conventionally known method. At this time, in order to remove ionic impurities, it may be brought into contact with an ion-adsorbing solid such as a layered silicate mineral.

The curable resin composition for a liquid crystal display element of the present invention contains an episulfide resin and a thermosetting agent, so that the episulfide resin has a fast thermosetting reaction and can prevent liquid crystal contamination due to the outflow of the episulfide resin. The curable resin composition for a liquid crystal display element of the present invention can be suitably used particularly when a liquid crystal display element is produced by a dropping method.

Such a sealing agent for liquid crystal display elements using the curable resin composition for liquid crystal display elements of the present invention is also one aspect of the present invention.
In addition, a method for sealing a liquid crystal display element using the liquid crystal display element sealant of the present invention is also provided.
It is one of the present inventions.

A vertical conduction material can be produced by blending conductive fine particles with the curable resin composition for a liquid crystal display element of the present invention and / or the sealing agent for a liquid crystal display element of the present invention. By using such a vertical conduction material, the electrodes of the transparent substrate can be conductively connected without contaminating the liquid crystal.
The vertical conduction material containing the curable resin composition for liquid crystal display elements of the present invention and / or the sealing agent for liquid crystal display elements of the present invention and conductive fine particles is also one aspect of the present invention.

The conductive fine particles are not particularly limited, and metal balls, those obtained by forming a conductive metal layer on the surface of resin fine particles, and the like can be used. Among them, the one in which the conductive metal layer is formed on the surface of the resin fine particles is preferable because the conductive connection is possible without damaging the transparent substrate due to the excellent elasticity of the resin fine particles.

The liquid crystal display element which uses the sealing compound for liquid crystal display elements of this invention and / or the vertical conduction material of this invention is also one of this invention.

According to the present invention, in the production of a liquid crystal display element, since the components do not dissolve in the liquid crystal and cause liquid crystal contamination, there is little color unevenness in the liquid crystal display. The optimal curable resin composition for liquid crystal display elements, the sealing agent for liquid crystal display elements, a vertical conduction material, and a liquid crystal display element can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Example 1)
40 parts by weight of bis A type epoxy acrylate (Daicel UBC, EB3700), bisphenol A type episulfide resin (Japan Epoxy Resin, YL7000)
) 20 parts by weight, hydrazide curing agent (manufactured by Ajinomoto Fine Techno Co., Ltd. as a latent thermosetting agent)
Amicure VDH) 10 parts by weight, 2,2-diethoxyacetophenone 1 part by weight as a photopolymerization initiator, 23 parts by weight of silica particles having an average particle diameter of 1.5 μm, and 1 part by weight of γ-glycidoxypropyltrimethoxysilane Were sufficiently mixed using three rolls to obtain a sealing agent for liquid crystal display elements.

Conductive fine particles having a conductive metal layer made of gold on the surface of resin fine particles made of styrene-divinylbenzene resin (Micropearl, manufactured by Sekisui Chemical Co., Ltd.) with respect to 100 parts by weight of the obtained sealing agent for liquid crystal display elements AU) 5 parts by weight was added and sufficiently kneaded to obtain a vertical conduction material.

The obtained sealing agent for a liquid crystal display element was applied to one of two transparent substrates with a transparent electrode using a dispenser so as to draw a rectangular frame. The obtained vertical conduction material was applied to the position of the electrode on the transparent substrate. Next, microdroplets of liquid crystal (manufactured by Chisso Corporation, JC-5004LA) are dropped on the entire surface of the frame with the sealant on the transparent substrate, and the other transparent substrate is immediately superimposed.
Temporary fixing was performed by irradiating ultraviolet rays with an intensity of 100 mW / cm ² for 30 seconds using a high-pressure mercury lamp. Thereafter, heating was performed at 120 ° C. for 1 hour, and liquid crystal annealing and main curing of the sealing agent for liquid crystal display elements were performed.
When the liquid crystal display element after the main curing was evaluated by visual observation, display unevenness was not recognized at all.

(Comparative Example 1)
Bisphenol A type episulfide resin (Japan Epoxy Resin YL7000)
Instead of 20 parts by weight, bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd.,
A sealing agent for liquid crystal display elements, a vertical conduction material and a liquid crystal display element were produced in the same manner as in Example 1 except that 20 parts by weight of Epicoat 828) was used.
When the liquid crystal display element after the main curing was evaluated by visual observation, display unevenness was observed around the sealing agent for the liquid crystal display element and the vertical conduction material.

According to the present invention, in the production of a liquid crystal display element, since the components do not dissolve in the liquid crystal and cause liquid crystal contamination, there is little color unevenness in the liquid crystal display. The optimal curable resin composition for liquid crystal display elements, the sealing agent for liquid crystal display elements, a vertical conduction material, and a liquid crystal display element can be provided.

Claims (8)

A curable resin composition for a liquid crystal display device, comprising an episulfide resin and a thermosetting agent. The curable resin composition for a liquid crystal display device according to claim 1, further comprising a radical polymerizable resin. The curable resin composition for a liquid crystal display device according to claim 2, wherein the radical polymerizable resin is a (meth) acrylic resin. 4. The curable resin composition for a liquid crystal display element according to claim 3, wherein the (meth) acrylic resin is epoxy (meth) acrylate or urethane (meth) acrylate. The curable resin composition for a liquid crystal display element according to claim 1, wherein the thermosetting agent is an amine or thiol type thermosetting agent. A sealing agent for liquid crystal display elements, comprising the curable resin composition for liquid crystal display elements according to claim 1, 2, 3, 4 or 5. The curable resin composition for a liquid crystal display element according to claim 1, 2, 3, 4 or 5, and / or 6.
A vertical conduction material comprising the sealing agent for liquid crystal display elements described above and conductive fine particles. A liquid crystal display element comprising the sealing agent for a liquid crystal display element according to claim 6 and / or the vertical conduction material according to claim 7.