JP2011090255A - Sealing agent for liquid crystal drop-fill method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing agent for a liquid crystal drop-fill method, excellent in drawing property, hardly causing contamination of a liquid crystal and giving a liquid crystal display device having high reliability. <P>SOLUTION: The sealing agent for a liquid crystal drop-fill method contains a curable resin and a radical polymerization initiator. The curable resin contains an epoxy (meth)acrylate obtained from, as a source material, at least one kind of epoxy resin selected from a group consisting of bisphenol-A epoxy resin, bisphenol-F epoxy resin, bisphenol-E epoxy resin, phenol novolac epoxy resin and cresol novolac epoxy resin, and a (meth)acrylic acid ester having a cyclic skeleton and two or more functional groups; not less than 70 mol% of curable reactive groups in the curable resin are (meth)acryl groups; the total content of the epoxy (meth)acrylate obtained from, as a source material, at least one kind of epoxy resin selected from the group consisting of bisphenol-A epoxy resin, bisphenol-F epoxy resin, bisphenol-E epoxy resin, phenol novolac epoxy resin and cresol novolac epoxy resin is 50 wt.% or more; and the content of the (meth)acrylic acid ester having a cyclic skeleton and two or more functional groups is 0.5 to 10 wt.% in the curable resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a sealant for a liquid crystal dropping method that is excellent in drawing properties, hardly causes liquid crystal contamination, and can provide a highly reliable liquid crystal display device.

In recent years, a method for manufacturing a liquid crystal display device such as a liquid crystal display cell has been disclosed in, for example, Patent Document 1 and Patent Document 2 from a conventional vacuum injection method from the viewpoint of shortening tact time and optimizing the amount of liquid crystal used. Such a photocurable resin, a photopolymerization initiator, a thermosetting resin, and a liquid crystal dropping method called a dropping method using a light and heat combined curing type sealant containing a thermosetting agent are being replaced.

In the dropping method, first, a rectangular seal pattern is formed on one of two transparent substrates with electrodes by dispensing. Next, a liquid crystal micro-droplet is dropped on the entire surface of the transparent substrate frame with the sealant being uncured, and the other transparent substrate is immediately overlaid, and the seal portion is irradiated with light such as ultraviolet rays to perform temporary curing. . After that, heating is performed at the time of liquid crystal annealing and main curing is performed to manufacture a liquid crystal display device. If the substrates are bonded together under reduced pressure, a liquid crystal display device can be manufactured with extremely high efficiency, and this dripping method is currently the mainstream method for manufacturing liquid crystal display devices.
In the manufacture of liquid crystal display devices by such a dripping method, the sealing agent directly contacts the liquid crystal in an uncured state, but at that time, the resin component is eluted into the liquid crystal, causing contamination, resulting in poor display of the liquid crystal display device. There was a problem of causing.

JP 2001-133794 A International Publication No. 02/092781 Pamphlet

An object of the present invention is to provide a sealing agent for a liquid crystal dropping method that has excellent drawing properties, hardly causes liquid crystal contamination, and can provide a highly reliable liquid crystal display device.

The present invention is a liquid crystal dropping method sealing agent containing a curable resin and a radical polymerization initiator, and the curable resin is a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol E type epoxy resin, An epoxy (meth) acrylate made from at least one epoxy resin selected from the group consisting of a phenol novolac epoxy resin and a cresol novolac epoxy resin, a cyclic skeleton, and a functional group number of 2 or more (Meth) acrylic acid ester, 70 mol% or more of the curable reactive group of the curable resin is a (meth) acrylic group, and the bisphenol A type epoxy resin and bisphenol F type epoxy in the curable resin. Resin, bisphenol E type epoxy resin, phenol novolac type epoxy The total content of epoxy (meth) acrylates starting from at least one epoxy resin selected from the group consisting of a resin and a cresol novolac type epoxy resin is 50% by weight or more, and the curable resin It is a sealing agent for liquid crystal dropping method in which the content of (meth) acrylic acid ester having a cyclic skeleton inside and having 2 or more functional groups is 0.5 to 10% by weight.
The present invention is described in detail below.

Considering the ability to suppress elution of the sealing agent component into the liquid crystal, 70 mol% or more of the reactive functional group of the curable resin is a (meth) acrylic group, and a hydroxyl group that is a representative hydrogen bonding functional group is added. It is preferable that the main component is an epoxy (meth) acrylate.
Furthermore, among epoxy (meth) acrylates having a hydroxyl group, an epoxy (B), a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol E type epoxy resin, a phenol novolac type epoxy resin, or a cresol novolac type epoxy resin as a raw material ( The (meth) acrylate can maintain the glass transition temperature (Tg) of the sealant at a certain level or more, make the liquid crystal display device highly reliable for high temperature and long-term use, and easy to obtain raw materials. Therefore, it is considered preferable to use the curable resin as a main component.
However, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, or epoxy (meth) acrylate using cresol novolac type epoxy resin as a raw material has a high viscosity and is a curable resin. When used as a main component, the viscosity of the sealant is difficult to adjust, and there is a problem that the degree of freedom of blending is substantially limited.

On the other hand, among epoxy (meth) acrylates having a hydroxyl group, those made from an epoxy compound derived from a compound having a non-phenolic hydroxyl group such as 1,6-hexanediol have a relatively low viscosity, but a bisphenol A type epoxy resin. Unlike the case where an epoxy compound having a phenolic hydroxyl group such as a raw material is used as a raw material, the purity of the epoxy compound used as a raw material of the epoxy (meth) acrylate is low, and the resulting epoxy (meth) acrylate contains a large amount of impurities, and the liquid crystal There is a problem that the sealant component elutes and causes liquid crystal contamination, which is not suitable as a main component of the curable resin.

Therefore, the present inventor has at least one epoxy resin selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin. As a result of intensive study on a curable resin that can adjust the viscosity of the sealant to a low level without causing liquid crystal contamination while having epoxy (meth) acrylate as a main component, it has a cyclic skeleton and has a functional group number. To produce a sealing agent for liquid crystal dropping method, by adding a small amount of (meth) acrylic acid ester of 2 or more, Tg is high, liquid crystal contamination can be suppressed, and viscosity can be adjusted low. As a result, the present invention has been completed.

The sealing agent for liquid crystal dropping method of the present invention contains a curable resin.
The curable resin is a resin having a reactive group (hereinafter also referred to as a curable reactive group) that undergoes a curing reaction alone or with other compounds by light, heat, or the like, such as an unsaturated double bond, an epoxy group, A resin having a reactive group such as an oxetane group or an isocyanate group can be mentioned, and a resin having a (meth) acrylic group and / or an epoxy group is preferable because the reaction can be easily controlled.
In the present specification, the (meth) acrylic means acryl or methacryl.

The curable resin is at least one epoxy resin selected from the group consisting of bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol E type epoxy resins, phenol novolac type epoxy resins, and cresol novolac type epoxy resins. The epoxy (meth) acrylate which uses as a raw material is contained.
In addition, in this specification, the said epoxy (meth) acrylate represents the compound which made all the epoxy groups in an epoxy resin react with (meth) acrylic acid.
Epoxy based on at least one epoxy resin selected from the group consisting of the above bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin It is preferable that the (meth) acrylate does not have a chain extended structure with ethylene oxide or propylene oxide. Epoxy based on at least one epoxy resin selected from the group consisting of the above bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin When (meth) acrylate has such a chain-extended structure, it may cause liquid crystal contamination.

Epoxy based on at least one epoxy resin selected from the group consisting of the above bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin Examples of commercially available (meth) acrylates include Evecri 3700 (manufactured by Daicel Cytec), epoxy ester 3002A, epoxy ester 3002M (all manufactured by Kyoeisha Chemical Co., Ltd.), and the like.

At least one epoxy selected from the group consisting of the bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin in the curable resin. The lower limit of the total content of epoxy (meth) acrylate using resin as a raw material is 50% by weight. Epoxy based on at least one epoxy resin selected from the group consisting of the above bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin When the total content of (meth) acrylate is less than 50% by weight, the display performance of the liquid crystal display device obtained by causing liquid crystal contamination is lowered, or the liquid crystal display device obtained by lowering Tg is reliable. It will be low. Epoxy based on at least one epoxy resin selected from the group consisting of the above bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin The minimum with preferable content of the total of (meth) acrylate is 60 weight%, and a preferable upper limit is 90 weight%.

The curable resin contains a (meth) acrylic acid ester having a cyclic skeleton and having two or more functional groups. The (meth) acrylic acid ester having the above-mentioned cyclic skeleton and having 2 or more functional groups has a role of adjusting the viscosity of the resulting sealant to improve drawing performance.
The (meth) acrylic acid ester having the cyclic skeleton and having two or more functional groups has a high Tg due to the cyclic skeleton, and can suppress liquid crystal contamination by having two or more functional groups.

The (meth) acrylic acid ester having the cyclic skeleton and having 2 or more functional groups is not particularly limited, and examples thereof include tricyclodecane dimethanol di (meth) acrylate and cyclohexane dimethanol di (meth) acrylate. It is done. Of these, tricyclodecane dimethanol di (meth) acrylate is preferred because of its low viscosity and high Tg.

The lower limit of the content of the (meth) acrylic acid ester having the cyclic skeleton in the curable resin and having 2 or more functional groups is 0.5% by weight, and the upper limit is 10% by weight. When the content of the (meth) acrylic acid ester having the cyclic skeleton and the number of functional groups is 2 or less is less than 0.5% by weight, the effect of adjusting the viscosity of the resulting sealant to a low level cannot be exhibited sufficiently. . When the content of the (meth) acrylic acid ester having the above cyclic skeleton and having 2 or more functional groups exceeds 10% by weight, liquid crystal contamination is caused and the display performance of the obtained liquid crystal display device is deteriorated. The preferable lower limit of the content of the (meth) acrylic acid ester having the cyclic skeleton and the number of functional groups of 2 or more is 2% by weight, and the preferable upper limit is 8% by weight.

The curable resin preferably further contains a resin having an epoxy group for the purpose of improving the adhesiveness of the resulting sealant.

The resin having an epoxy group is not particularly limited, but is selected from the group consisting of the bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and high compatibility with epoxy (meth) acrylate using at least one kind of epoxy resin as a raw material, and And at least one epoxy resin selected from the group consisting of cresol novolac epoxy resins.

As the resin having an epoxy group, a partial (meth) acryl-modified epoxy resin obtained by reacting a part of the epoxy group of a resin having two or more epoxy groups in one molecule with (meth) acrylic acid is used. You can also.

The resin having two or more epoxy groups in one molecule is not particularly limited, but bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin. Preferably, the partial (meth) acryl-modified epoxy resin is, for example, 1 mol of bisphenol F-type epoxy resin and 1 acrylic acid. Examples thereof include compounds obtained by reacting with mol.

A partial (meth) acryl-modified epoxy resin obtained by reacting a part of an epoxy group of a resin having two or more epoxy groups in one molecule with (meth) acrylic acid is usually an excess reaction product and an unreacted product. And become a mixture.
Specifically, a compound obtained by reacting 1 mol of a resin having two epoxy groups in one molecule with 1 mol of (meth) acrylic acid has both two epoxy groups unless special treatment is performed. About 25 mol% of the acrylated compound, one epoxy group is acrylated, one epoxy group remains unreacted about 50 mol%, both epoxy groups remain unreacted A mixture containing about 25 mol% of the three compounds with the remaining compound is obtained.
That is, at least one epoxy resin selected from the group consisting of the above bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin, The compounds obtained when the (meth) acrylic acid is reacted at an equal molar ratio are the above bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolak. This is a mixture containing about 25 mol% of epoxy (meth) acrylate made from at least one epoxy resin selected from the group consisting of type epoxy resins.

When the said curable resin contains the resin which has the said epoxy group, the minimum with preferable content of the resin which has the said epoxy group in the said curable resin is 3 weight%, and a preferable upper limit is 20 weight%. If the content of the resin having an epoxy group is less than 3% by weight, the effect of improving the adhesiveness of the sealing agent may not be sufficiently obtained. When the content of the epoxy group-containing resin exceeds 20% by weight, the solubility of the curable resin in the liquid crystal is increased, causing liquid crystal contamination, and the display performance of the obtained liquid crystal display device may be deteriorated. The more preferable lower limit of the content of the resin having an epoxy group is 5% by weight, and the more preferable upper limit is 15% by weight.
When using a partial (meth) acryl-modified epoxy resin obtained by reacting a part of the epoxy group of a resin having two or more epoxy groups in one molecule with (meth) acrylic acid as the resin having the epoxy group The preferable lower limit of the content of the partial (meth) acryl-modified epoxy resin in the curable resin is 5% by weight, and the preferable upper limit is 40% by weight. If the content of the partial (meth) acryl-modified epoxy resin is less than 5% by weight, the effect of improving the adhesiveness of the sealant may not be sufficiently obtained. If the content of the partial (meth) acrylic-modified epoxy resin exceeds 40% by weight, the solubility of the curable resin in the liquid crystal becomes high, causing liquid crystal contamination, and the display performance of the resulting liquid crystal display device is deteriorated. There is. A more preferable range of the content of the partial (meth) acryl-modified epoxy resin is 10% by weight, and a more preferable upper limit is 30% by weight.

As said curable resin, unless the objective of this invention is impaired, you may mix | blend other resin further, However, It is preferable to be comprised without mix | blending the said other resin.

The lower limit of the ratio of acrylic groups to the total amount of curable reactive groups in the entire curable resin is 70 mol%. When the acrylic group ratio is less than 70 mol%, the solubility in the liquid crystal becomes high, and the display performance of the liquid crystal display device obtained by causing liquid crystal contamination is lowered. The minimum with the preferable ratio of the said acrylic group is 75 mol%. Moreover, the upper limit with the preferable ratio of the said acrylic group is 90 mol%. When the acrylic group ratio exceeds 90 mol%, the resulting sealant may be inferior in adhesiveness.

Although the hydroxyl value of the said curable resin is not specifically limited, A preferable minimum is 2.5 * 10 < ^-3 > mol / g and a preferable upper limit is 4.5 * 10 < ^-3 > mol / g. When the hydroxyl value is less than 2.5 × 10 ⁻³ mol / g, the solubility in liquid crystals increases, causing liquid crystal contamination, and the display performance of the resulting liquid crystal display device may be lowered. When the hydroxyl value exceeds 4.5 × 10 ⁻³ mol / g, the resulting sealant may be inferior in water resistance.

The hydroxyl value (OH _X ) of the resin X in the curable resin is calculated by the following formula (1).

OH _X = (number of hydroxyl groups in one molecule of resin X) / (molecular weight of resin X) (1)

In the sealing agent for liquid crystal dropping method of the present invention, the curable resin is composed of a mixture of a plurality of resins as described above, and the hydroxyl value of the curable resin is the hydroxyl value of each resin and the curable resin. It can be calculated from the weight fraction. For example, the hydroxyl value (OH _ABC ) when the curable resin is composed of Resin A, Resin B, and Resin C is represented by the following formula (2).

_{OH ABC = OH A × P A} + OH B × P B + OH C × P C (2)

In the above formula (2), P _α represents the weight fraction of the resin α.

Specifically, for example, curable resin is distilled bisphenol A type epoxy acrylate (molecular weight 484, hydroxyl number 2 in one molecule) 75% by weight, 50% partially acrylic modified distilled bisphenol F type epoxy resin (molecular weight 312 A mixture containing 25 mol% of a compound having no molecular weight, 50 mol% of a compound having a molecular weight of 384 and one hydroxyl group in one molecule, and 25 mol% of a compound having a molecular weight of 456 and two hydroxyl groups in one molecule) In the case where it is composed of 20% by weight and 5% by weight of tricyclodecane dimethanol diacrylate (molecular weight 304, no hydroxyl group), the hydroxyl value of the curable resin is calculated from the above formula (2) (2/484) × 0.75 + (0/312) × 0.20 × 0.2033 + (1/384) × 0.20 × 0.5 + (2/456) × 0.2 × 0.2967 = 3 62 × a ^{10 -3} mol / g.
In this example, the 50% acrylic modified distilled bisphenol F type epoxy resin is 25 mol% of a compound in which both of two epoxy groups are acrylated (a compound having a molecular weight of 456 and 2 hydroxyl groups in one molecule), One epoxy group is acrylated and one epoxy group remains unreacted (a compound having a molecular weight of 384 and one hydroxyl group in one molecule) of 50 mol%, and both epoxy groups are both Since it was assumed that 25 mol% of the compound that remained unreacted (compound having a molecular weight of 312 and no hydroxyl group) was contained, both of the two epoxy groups in the 50% acrylic-modified distilled bisphenol F type epoxy resin were acrylated. The content of the resulting compound was 0.2033% by weight, one epoxy group was acrylated and one epoxy group remained unreacted 0.5 wt% the content of the object was calculated both two epoxy groups a content of still remaining unreacted compound as 0.2967 wt%.

The sealing agent for liquid crystal dropping method of the present invention contains a radical polymerization initiator. The radical polymerization initiator generates radicals by light or heat.

Among the above radical polymerization initiators, the photo radical polymerization initiator that generates radicals by light is not particularly limited, and examples thereof include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, Examples include benzoin ether compounds, benzyl, thioxanthone, and the like.
Examples of commercially available photo radical polymerization initiators include Irgacure 184, Irgacure 369, Irgacure 379, Irgacure 651, Irgacure 819, Irgacure 907, Irgacure 2959, Irgacure OXE01 (all manufactured by Ciba Japan). Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether (all of which are manufactured by Tokyo Chemical Industry Co., Ltd.), lucillin TPO (manufactured by BASF Japan), and the like.

Although content of the said radical photopolymerization initiator is not specifically limited, A preferable minimum is 0.1 weight part and a preferable upper limit is 10 weight part with respect to 100 weight part of said curable resins. When the content of the radical photopolymerization initiator is less than 0.1 parts by weight, the polymerization may not proceed sufficiently or the reaction may be too slow. When the content of the radical photopolymerization initiator exceeds 10 parts by weight, the reaction becomes too fast and workability may be deteriorated or the reaction may become uneven.

Among the radical polymerization initiators, the thermal radical polymerization initiator that generates radicals by heat is not particularly limited, and examples thereof include peroxides and azo compounds.
Examples of commercially available thermal radical polymerization initiators include perbutyl O, perhexyl O, perbutyl PV (all manufactured by NOF Corporation), V-30, V-501, V-601, and VPE-0201. (Both manufactured by Wako Pure Chemical Industries, Ltd.).

Although content of the said thermal radical polymerization initiator is not specifically limited, A preferable minimum is 0.1 weight part and a preferable upper limit is 10 weight part with respect to 100 weight part of said curable resins. If the content of the thermal radical polymerization initiator is less than 0.1 parts by weight, the polymerization may not proceed sufficiently or the reaction may become too slow. When the content of the thermal radical polymerization initiator exceeds 10 parts by weight, the reaction becomes too fast, and workability may be lowered or the reaction may become uneven.

Moreover, when the said curable resin contains the resin which has the said epoxy group, it is preferable that the sealing compound for liquid crystal dropping methods of this invention contains a thermosetting agent.
The said thermosetting agent is not specifically limited, For example, organic acid hydrazide, an imidazole derivative, an amine compound, a polyhydric phenol type compound, an acid anhydride etc. are mentioned. Among these, solid organic acid hydrazide is preferably used.

The solid organic acid hydrazide is not particularly limited, and examples thereof include sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, malonic acid dihydrazide, and the like. All include Ajinomoto Fine Techno Co., Ltd.), ADH (Otsuka Chemical Co., Ltd.) and the like.

The sealing agent for liquid crystal dropping method of the present invention preferably further contains a silane coupling agent. The silane coupling agent mainly has a role as an adhesion aid for favorably bonding the liquid crystal dropping method sealing agent and the substrate or the like.

Although the silane coupling agent is not particularly limited, it is excellent in the effect of improving adhesiveness with a substrate and the like, and it can suppress the outflow of the curable resin into the liquid crystal by chemically bonding with the curable resin. For example, γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-isocyanatopropyltrimethoxysilane and the like are preferably used. These silane coupling agents may be used independently and 2 or more types may be used together.

The sealing agent for liquid crystal dropping method of the present invention preferably contains a filler for the purpose of improving the adhesiveness by the stress dispersion effect, improving the linear expansion coefficient, and the like.
The filler is not particularly limited. For example, talc, asbestos, silica, diatomaceous earth, smectite, bentonite, calcium carbonate, magnesium carbonate, alumina, montmorillonite, diatomaceous earth, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, water Inorganic fillers such as magnesium oxide, aluminum hydroxide, glass beads, silicon nitride, barium sulfate, gypsum, calcium silicate, sericite activated clay, aluminum nitride, polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, acrylic polymer fine particles, etc. The organic filler is mentioned.

The sealing agent for the liquid crystal dropping method of the present invention further includes a reactive diluent for adjusting the viscosity, a thixotropic agent for adjusting the thixotropy, a spacer such as a polymer bead for adjusting the panel gap, if necessary. It may contain a curing accelerator such as -P-chlorophenyl-1,1-dimethylurea, an antifoaming agent, a leveling agent, a polymerization inhibitor, and other additives.

The viscosity of the sealing agent for liquid crystal dropping method of the present invention is not particularly limited, but the preferred lower limit when measured using an E-type viscometer under the conditions of 25 ° C. and 1 rpm is 150 Pa. s, the preferred upper limit is 450 Pa. s. The viscosity is 150 Pa. If it is less than s, the coated sealing agent may be pushed by the liquid crystal and flow. The viscosity is 450 Pa. If s is exceeded, the seal pattern may not be drawn on the substrate, or the seal pattern drawn on the substrate may break, and the liquid crystal may leak from the broken portion.

The method for producing the liquid crystal dropping method sealing agent of the present invention is not particularly limited. For example, a curable resin, a radical polymerization initiator, an additive blended as necessary, and the like are used in three rolls. And a method of mixing and uniformly dispersing by a conventionally known method.

ADVANTAGE OF THE INVENTION According to this invention, the sealing agent for liquid crystal dropping methods which is excellent in drawing property, hardly causes liquid crystal contamination, and can obtain a reliable liquid crystal display device 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.

(Synthesis of partially acrylic-modified epoxy resin)
312 g of bisphenol F type epoxy resin (manufactured by DIC, “EPICLON EXA-830CRP”) was dissolved in 600 mL of toluene, and 0.2 g of triphenylphosphine was added to the solution to obtain a uniform solution. To the obtained solution, 72 g of acrylic acid was added dropwise over 2 hours with stirring under reflux, followed by further stirring under reflux for 6 hours. Next, by removing toluene, a resin (50% partially acrylic modified bisphenol F type epoxy resin) in which 50 mol% of the epoxy group was modified with acrylic was obtained.
As a result of analysis by liquid chromatography, the obtained 50% partially acrylic-modified bisphenol F type epoxy resin contained about 22 mol% (about 26.3 wt%) of a compound (molecular weight 456) in which both epoxy groups were acrylated. %) About 53 mol% (about 53.3% by weight) of a compound in which one epoxy group was acrylated and one epoxy group remained unreacted (molecular weight 384), and both epoxy groups were both Both were mixtures containing about 25 mol% (about 20.4 wt%) of the compound (molecular weight 312) that remained unreacted.

Example 1
As a curable resin, 85 parts by weight of bisphenol A type epoxy acrylate (manufactured by Daicel Cytec Co., Ltd., “Eveacryl 3700”), 5 parts by weight of tricyclodecane dimethanol diacrylate (manufactured by Daicel Cytec Co., Ltd., “IRR214”), and synthesized. 10 parts by weight of 50% partially acrylic-modified bisphenol F-type epoxy resin, 1 part by weight of 1-hydroxycyclohexyl phenyl ketone (Ciba Japan Co., Ltd., “Irgacure 184”) as a radical polymerization initiator, and adipic acid dihydrazide as a thermosetting agent 1.2 parts by weight (manufactured by Otsuka Chemical Co., Ltd., “ADH”), 25 parts by weight of silica (manufactured by Admatechs, “Admafine SO-C2”) as filler, and γ-glycidoxypropyl as a silane coupling agent Trimethoxysilane (Shin-Etsu Silicone 1 part by weight of “KBM-403” (manufactured by Kogyo Co., Ltd.) was mixed using a planetary stirrer (manufactured by Shinky Co., “Narotaro Awatori”), and then further mixed using three rolls for sealing. An agent was prepared.

The curable resin used was analyzed by liquid chromatography. As a result, the bisphenol A type epoxy acrylate has a molecular weight of 484, a compound in which both of the two epoxy groups are acrylated is about 82 mol% (about 74.2% by weight), and the molecular weight is 768. The mixture contained about 18 mol% (about 25.8 wt%) of a compound in which both two epoxy groups were acrylated.
Tricyclodecane dimethanol diacrylate was almost composed of a compound having a molecular weight of 304.

(Examples 2-9, Comparative Examples 1-7)
A sealant was prepared in the same manner as in Example 1 except that the materials used and the blending amounts were those shown in Tables 1 and 2.
The bisphenol A type epoxy resin used in Examples 4 to 6 and Comparative Example 4 is EPICLON EXA-850CRP (manufactured by DIC), and the propylene glycol epoxy acrylate used in Comparative Example 1 is an epoxy ester 70PA (Kyoeisha). The isobornyl acrylate used in Comparative Example 3 is light acrylate IB-XA (manufactured by Kyoeisha Chemical Co., Ltd.).

The curable resin used was analyzed by liquid chromatography. As a result, the bisphenol A type epoxy resin was almost composed of a compound having a molecular weight of 340.
Propylene glycol epoxy acrylate is a compound having a molecular weight of 332, about 52 mol% (about 44.9 wt%), a molecular weight of 424, about 33 mol% (about 36.3% by weight), and a molecular weight of 516 Was about 14 mol% (about 18.8 wt%). The compound having a molecular weight of 332 is propylene glycol epoxy acrylate, and the compound having a molecular weight of 424 and the compound having a molecular weight of 516 are considered to be an epichlorohydrin abnormal adduct of an epoxy compound as a precursor.
Furthermore, isobornyl acrylate was almost composed of a compound having a molecular weight of 208.

About the sealing agent obtained by the Example and the comparative example, the ratio of the (meth) acryl group in the curable reactive group of curable resin, the bisphenol A type epoxy acrylate in curable resin, and 50% partially acrylic modified bisphenol F type The total content of bisphenol F type epoxy acrylate in which the epoxy group in the epoxy resin is completely acrylated, the content of tricyclodecane dimethanol diacrylate in the curable resin, and the hydroxyl value of the curable resin The results are shown in Tables 1 and 2.

<Evaluation>
The following evaluation was performed about the sealing agent obtained by the Example and the comparative example. The results are shown in Tables 1 and 2.

(1) Viscosity After the obtained sealing agent was vacuum degassed, the viscosity was measured using an E-type viscometer (manufactured by Brookfield, “DV-III”) at 25 ° C. and 1 rpm.

(2) Drawing property The obtained sealing agent was put into a syringe, and a straight line was drawn under the conditions of 80 mm / sec, nozzle diameter 0.2 mm, and coating pressure 250 kPa using a dispenser (manufactured by Musashi Engineering).
“◎” when a straight line can be drawn without cutting or fading at all, “○” when there is a slight fading but “△” when drawing a straight line without cutting, “△” when there is a cutting, almost no sealant from the nozzle The case where it did not come out was evaluated as “×”.

(3) Adhesive strength Uniform liquid obtained by dispersing 3 parts by weight of polymer beads (“Micropearl SP”, manufactured by Sekisui Chemical Co., Ltd.) with an average particle diameter of 5 μm with respect to 100 parts by weight of the obtained sealant using a planetary stirrer. It was. A very small amount of the obtained liquid was placed in the center of a glass substrate Corning 1737 (20 mm × 50 mm × 0.7 mmt), and the same type of glass substrate was overlaid thereon to spread the liquid crystal dropping method sealant. In this state, ultraviolet rays were irradiated at 100 mW / cm ² for 20 seconds. Then, it heated at 120 degreeC for 1 hour, and obtained the adhesion test piece. About the obtained adhesion test piece, the adhesive strength was measured using the tension gauge (comparative unit: N / cm < ² >).

(4) The obtained sealant was applied with a dispenser so as to draw a square frame on the alignment film of the substrate having the non-uniform color transparent electrode and the alignment film (“SE-7492”, manufactured by Nissan Chemical Co., Ltd.). . Subsequently, fine droplets of liquid crystal (manufactured by Chisso Corporation, “JC-5004LA”) were dropped onto the sealant frame on the substrate, and the substrate having another transparent electrode and an alignment film was superposed in a vacuum. . After releasing the vacuum, the sealing agent was irradiated with ultraviolet rays of 2000 mJ / cm ² and then heated at 120 ° C. for 1 hour to cure the sealing agent to obtain a liquid crystal display panel.
About the obtained liquid crystal display panel, the color unevenness which arises in the liquid crystal around a sealing agent was visually observed in the lighting state and the non-lighting state. The case where there was no color unevenness was evaluated as “◎”, the case where there was almost no color unevenness, “◯”, the case where there was a little color unevenness as “△”, and the case where there was considerable color unevenness as “×”. .
Further, the obtained liquid crystal display panel was evaluated in the same manner after being left for 500 hours at 80 ° C.

ADVANTAGE OF THE INVENTION According to this invention, the sealing agent for liquid crystal dropping methods which is excellent in drawing property, hardly causes liquid crystal contamination, and can obtain a reliable liquid crystal display device can be provided.

Claims (4)

A liquid crystal dropping method sealing agent containing a curable resin and a radical polymerization initiator,
The curable resin is at least one epoxy resin selected from the group consisting of bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol E type epoxy resins, phenol novolac type epoxy resins, and cresol novolac type epoxy resins. Containing (epoxy (meth) acrylate) and (meth) acrylic acid ester having a cyclic skeleton and having 2 or more functional groups,
70 mol% or more of the curable reactive group of the curable resin is a (meth) acryl group,
At least one epoxy resin selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin in the curable resin. Of (meth) acrylic acid ester having a total content of epoxy (meth) acrylates starting from 50% by weight and having a cyclic skeleton in the curable resin and having 2 or more functional groups A sealing agent for liquid crystal dropping method, wherein the content is 0.5 to 10% by weight. The curable resin is at least one epoxy resin selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin. The sealing agent for liquid crystal dropping method according to claim 1, which is contained. The liquid crystal dropping method seal according to claim 1 or 2, wherein the (meth) acrylic acid ester having a cyclic skeleton and having 2 or more functional groups is tricyclodecane dimethanol di (meth) acrylate. Agent. Liquid crystal dropping process for sealing agent according to claim 1, 2 or 3, wherein the hydroxy value is 2.5 × ^{10 -3} ~4.5 × ¹⁰ -3 mol / g of resin.