JPH0933932A - Sealing material composition for liquid crystal display element and liquid crystal display element formed by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of a liquid crystal display element by incorporating a liquid polybutadiene resin having an acid anhydride group in the molecule into a hardener as an essential component. SOLUTION: The liquid polybutadiene resin having the acid anhydride group in the molecule as part of the hardener is used as the essential component of the one pack type adhesive compsn. consisting essentially of an epoxy resin, hardener and inorg. filler. In such a case, the liquid polybutadiene resin having the acid anhydride group in the molecule to be used as the essential component is effective in improving the flexibility and thermal impact resistance of the epoxy resin as the trunk structure has adequate resilience. Namely, the liquid polybutadiene resin having the acid anhydride as part of the hardener is used as the essential component, by which the sealing material compsn. having the wet heat resistance sufficiently high as the sealing material for the liquid crystal display element and having the toughness to sufficiently withstand the temp. conditions conceivable in the production process and use condition of the liquid crystal display element and the stresses generated by a temp. change, etc., is obtd.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a sealing material composition for a liquid crystal display device and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have become widespread due to their features such as light weight, thin shape, and low power consumption. The liquid crystal display element has a structure in which the liquid crystal is sandwiched between glass or plastic substrates, and the periphery is sealed with an adhesive so that the liquid crystal does not leak outside. Generally, this is a seal for the liquid crystal display element. It is called a material (abbreviation of liquid crystal sealing material).

At present, epoxy resin is widely used for the liquid crystal sealing material, but a more excellent liquid crystal sealing material is demanded in order to improve the reliability of the liquid crystal display element, for example, resistance to moist heat. Japanese Patent Publication Nos. 64-5630 and 4-506, using epoxy resin as a sealing material for liquid crystal displays.
No. 3, there is a heat resistance of the cured product when using the epoxy resin described in these as a liquid crystal sealing material,
Since the moisture resistance is insufficient, the reliability as a liquid crystal display element is low. Specifically, when a silicone rubber or the like described in Japanese Patent Publication No. 4-5063 is blended, a low-molecular weight silicone component bleeds when heated, resulting in poor adhesion of ACF or liquid crystal under high temperature and high humidity environment. When the display panel is exposed, peeling may occur due to a decrease in the adhesive strength of the seal portion, making it difficult to maintain an appropriate gap and causing a display defect or the like.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a sealing material for a liquid crystal display element which improves the reliability of the liquid crystal display element as compared with the conventional liquid crystal sealing material, and a liquid crystal display element using the same. .

[0005]

The present invention provides a one-pack type adhesive composition containing an epoxy resin, a curing agent, and an inorganic filler as main components, and as a part of the curing agent, an acid anhydride group in the molecule. A liquid sealing material composition for a liquid crystal display device, which comprises a liquid polybutadiene resin having the following as an essential component.

The liquid polybutadiene resin having an acid anhydride group in the molecule, which is used as an essential component in the present invention, has a suitable trunk structure, so that the flexibility and thermal shock resistance of the epoxy resin are improved. It is well known that this is effective in improving. It was found that excellent properties can be obtained even when this is compounded as a part of a curing agent for a liquid crystal sealing material, and the present invention has been completed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The characteristics required of a sealing material for a liquid crystal display device are that liquid crystal sandwiched between two glass substrates does not leak out under various conditions. Secondly, it is possible to prevent the display abnormality from being caused by the invasion of water from the outside. With respect to any of the required characteristics, the sealing material is required to have good adhesiveness to glass under various conditions. In particular, since the gap between the two glass substrates is as small as several μm, the stress caused by the difference in the thermal expansion coefficient between the glass substrate and the sealing material due to the temperature change in the sealing material and the adhesive portion may cause peeling and cracking. It is important to absorb without causing it. From such a point of view, conventional sealing materials for liquid crystal display elements have been exclusively added with a component such as a silicone component that lowers the elastic modulus (for example, JP-B-4-5063 and JP-A-6-73164). No. 6-75231). However, by adding such a component that lowers the elastic modulus, the wet heat resistance of the cured seal material itself is reduced to cause poor adhesion to glass, or a low molecular weight component is eluted from the cured seal material into the liquid crystal. Or, along with that, the adhesion of other peripheral materials to the glass is hindered, and this is not a fundamental solution. That is, it is the best measure to impart toughness against stress while having resistance to moist heat, and to eliminate low molecular weight components that are eluted from the cured material of the sealing material due to the external environment. The inventors of the present invention use a liquid polybutadiene resin having an acid anhydride group in the molecule as a part of a curing agent to incorporate such a flexible component into a crosslinked structure and to elute it from a cured product of a sealing material. It has been found that it is possible to eliminate the molecular weight component.

As a result of intensive studies made by the present inventors from such a point, a liquid polybutadiene resin having an acid anhydride group in the molecule as a part of a curing agent is used as an essential component, whereby a sealing material for a liquid crystal display device is obtained. As a result, it has been found that it has sufficiently high resistance to moisture and heat and has sufficient toughness to withstand stress generated by temperature conditions and temperature changes that can be considered in the manufacturing process and use conditions of the liquid crystal display element.

The epoxy resin used is not particularly limited. For example, bisphenol A type epoxy resin, alkyl-substituted bisphenol A type epoxy resin, bisphenol F type epoxy resin, alkyl substituted bisphenol F type epoxy resin, bisphenol S type epoxy resin. Resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, glycidyl ester type epoxy resin, alicyclic epoxy resin, urethane Modified epoxy resin etc. are available.

Further, the curing agent is not particularly limited in addition to the liquid polybutadiene resin having an acid anhydride group in the molecule, and is an amine curing agent generally used as a curing agent for epoxy resins. , Imidazole type curing agent, dicyandiamide, hydrazide type curing agent, acid anhydride type curing agent, phenol type curing agent, etc. can be used,
These microencapsulated curing agents, adduct type curing agents, etc. can be used to further improve the storability, and a curing accelerator can also be used in combination therewith. As the curing accelerator, phosphorus compounds, imidazole compounds,
Urea compounds, dibasic acid compounds, DBU salts and the like are generally used.

Examples of inorganic fillers include carbonates, sulfates, alumina, silica, titanium oxides of various metals,
Examples thereof include potassium titanate, and among these, it is preferable to use one kind or two or more kinds of alumina and silica in combination from various points. Further, the amount of the inorganic filler added is 3 to 5 out of the total composition in view of workability such as printability.
It is preferably 0% by weight.

If necessary, a solvent may be added for the purpose of adjusting the viscosity of the sealing material composition and uniformly mixing the components.
The solvent used is also not particularly limited, but for example n
-Hydrocarbon solvents such as hexane, n-decane and cyclohexane, aromatic hydrocarbon solvents such as benzene, toluene and xylene, ester solvents such as butyl acetate and benzyl acetate, methyl cellosolve, butyl cellosolve, methyl carbitol and ethyl. Polyhydric alcohols such as carbitol, butyl carbitol, methyl cellosolve acetate, ethylene glycol, diethylene glycol and diglyme, and their derivatives are used alone or in combination of two or more. From the viewpoint of printability and the like, the amount of the solvent added is preferably 2 to 50% by weight based on all components.

Further, a coupling agent, a defoaming agent, a leveling agent and the like may be added in addition to the above-mentioned epoxy resin, curing agent and inorganic filler which are essential components in the present invention. When preparing the sealant composition for a liquid crystal display device of the present invention, it is preferable to sufficiently knead the components using a three-roll roll or the like in order to uniformly mix the components.

As a method for producing a liquid crystal display element using the sealant composition for a liquid crystal display element of the present invention, there are generally the following methods. First, a seal pattern is formed on one side of a glass substrate on which a liquid crystal alignment layer is formed by a process such as screen printing, preliminarily dried by a dryer or the like, and then the other substrate is bonded and pressed as necessary. Then, it is further heated and cured in a drying oven or the like. Pre-drying is usually 50-1
5 to 60 minutes at 20 ° C, heat curing is usually 100 to 200 ° C
15 to 180 minutes is suitable. Further, in order to maintain the gap between the two substrates, the sealing material may contain a spherical or rod-shaped spacer having a predetermined diameter. Liquid crystal is injected into the bonded substrates, and the injection port is sealed with UV curable resin or the like to form a liquid crystal display element.

[0015]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 As an epoxy resin, a bisphenol A type epoxy resin (produced by Yuka Shell Epoxy Co., Ltd.,
Epicoat 828) 80 parts by weight, bisphenol A type epoxy resin (Okaka Shell Epoxy Co., Epicoat 10
01) 20 parts by weight, 10 parts by weight of adipic dihydrazide (manufactured by Otsuka Chemical Co., Ltd.) as a curing agent, liquid polybutadiene resin having a maleic anhydride group (manufactured by Nippon Petrochemical Co., M-
1000-80) 3 parts by weight, amorphous silica as an inorganic filler (Aerosil R-972 manufactured by Nippon Aerosil Co., Ltd.) 5
Parts by weight, spherical silica (Admatex, SO-C
4) 20 parts by weight and 13 parts by weight of ethyl carbitol as a solvent were mixed by stirring, and further sufficiently kneaded with a three-roll to obtain an adhesive composition.

Next, 1% of a spherical silica spacer having a diameter of 5 μm was mixed with this adhesive composition to prepare a liquid crystal cell in the following manner. (Screen printing) A square pattern having a line width of 0.3 mm was screen-printed on a glass substrate with ITO (square having a side of 3 cm) on which an alignment film was formed using a 300 mesh plate. (Preliminary Drying) Preliminary drying was performed in a hot air dryer at 90 ° C. for 30 minutes. (Adhesion / Curing by heat) An ITO-attached glass substrate having an alignment film formed thereon is attached so that the orientation direction is 90 degrees with respect to the orientation treatment direction of the substrate on which the sealing material is printed.
170 ℃ / in a hot air dryer with a pressure of 1kg / cm ²
It was cured by heating for 120 minutes. (Liquid crystal injection / sealing) Fluorine-based liquid crystal (Merck, ZLI
-4792), and the inlet was sealed with an acrylic UV curable resin.

The following items were evaluated for evaluation. (1) Adhesive force after heat curing (peeling off the glass substrate with a knife) (2) Adhesive force after pressure cooker test (PCT) (125 ° C / 100% RH /
After performing the treatment for 24 hours under the condition of 2.3 atm, the same peeling was performed. (3) Presence or absence of display unevenness due to PCT (a rectangular wave of ± 3 V is applied to the above-mentioned PCT-treated liquid crystal cell to evaluate display unevenness) The evaluation results are shown in Table 1.

Example 2 As the epoxy resin, a bisphenol A type epoxy resin (produced by Yuka Shell Epoxy Co., Ltd.,
Epicoat 828) 40 parts by weight, bisphenol A type epoxy resin (Okaka Shell Epoxy Co., Epicoat 10
01) 30 parts by weight, o-cresol novolac type epoxy resin (Sumitomo Chemical Co., Ltd., ESCN-195LB) 10 parts by weight, glycidyl amine type epoxy resin (Okaka Shell Epoxy Co., Epicoat 604) 20 parts by weight, as a curing agent 15 parts by weight of dicyandiamide, a liquid polybutadiene resin having a maleic anhydride group (manufactured by Nippon Petrochemical Co., Ltd., M-
2000-80) 5 parts by weight, amorphous silica as an inorganic filler (Aerosil R-972 manufactured by Nippon Aerosil Co., Ltd.) 5
Parts by weight, alumina (UA-5055, Showa Denko KK) 2
0 parts by weight and 20 parts by weight of methyl carbitol as a solvent were stirred and mixed, and further sufficiently kneaded with a three-roll to obtain an adhesive composition. A 1% spherical silica spacer having a diameter of 5 μm was mixed with this adhesive composition to prepare a liquid crystal cell in the same manner as in Example 1. The evaluation results are as shown in Table 1.

Example 3 As an epoxy resin, 50 parts by weight of a dicyclopentadiene type epoxy resin (HP-7200, manufactured by Dainippon Ink and Chemicals, Inc.), a bisphenol A type epoxy resin (produced by Yuka Shell Epoxy, Epicoat 8)
28) 50 parts by weight of a liquid polybutadiene resin having a maleic anhydride group (manufactured by Nippon Petrochemical Co., Ltd., M-1000-2
0) 10 parts by weight, 10 parts by weight of adipic dihydrazide (manufactured by Otsuka Chemical Co., Ltd.) as a curing agent, and amorphous silica (manufactured by Nippon Aerosil Co., Ltd., Aerosil R-972) as an inorganic filler.
5 parts by weight, spherical silica (manufactured by Admatex, SO-C
4) 20 parts by weight and 13 parts by weight of ethyl carbitol as a solvent were mixed by stirring, and further sufficiently kneaded with a three-roll to obtain an adhesive composition. A 1% spherical silica spacer having a diameter of 5 μm was mixed with this adhesive composition to prepare a liquid crystal cell in the same manner as in Example 1. The evaluation results are as shown in Table 1.

(Example 4) As an epoxy resin, a naphthalene type epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., HP
-4032) 40 parts by weight, bisphenol A type epoxy resin (Eikato Shell Epoxy Co., Epicoat 834) 5
0 parts by weight, 10 parts by weight of o-cresol novolac type epoxy resin (ESCN-195LB manufactured by Sumitomo Chemical Co., Ltd.), 8 parts by weight of adipic acid dihydrazide (manufactured by Otsuka Chemical Co., Ltd.) as a curing agent, liquid polybutadiene resin having a maleic anhydride group. (Nippon Petrochemical Co., Ltd., M-3000-20) 2 parts by weight, amorphous silica (Nippon Aerosil Co., Ltd., NAX50) 5 parts by weight, spherical silica (Admatex Co., SO-C4) 15 parts by weight as an inorganic filler. Parts and 20 parts by weight of methyl carbitol as a solvent were mixed by stirring, and further sufficiently kneaded with a three-roll mill to obtain an adhesive composition. A 1% spherical silica spacer having a diameter of 5 μm was mixed with this adhesive composition to prepare a liquid crystal cell in the same manner as in Example 1. Table 1 shows the evaluation results.
As shown in.

(Comparative Example 1) As an epoxy resin, a bisphenol A type epoxy resin (made by Yuka Shell Epoxy Co., Ltd.,
Epicoat 828) 80 parts by weight, bisphenol A type epoxy resin (Okaka Shell Epoxy Co., Epicoat 10
01) 20 parts by weight, 10 parts by weight of adipic dihydrazide (manufactured by Otsuka Chemical Co., Ltd.) as a curing agent, and amorphous silica (manufactured by Nippon Aerosil Co., Ltd., Aerosil R-97) as an inorganic filler.
2) 5 parts by weight, spherical silica (Admatex, SO
-C4) 20 parts by weight, ethyl carbitol 1 as a solvent
3 parts by weight were mixed by stirring, and further kneaded with a three-roll mill to obtain an adhesive composition. This adhesive composition has a diameter of 5μ
A spherical silica spacer of m was mixed with 1%, and a liquid crystal cell was produced in the same manner as in Example 1. The evaluation results are as shown in Table 1.

(Comparative Example 2) As an epoxy resin, a bisphenol A type epoxy resin (made by Yuka Shell Epoxy Co.,
Epicoat 828) 40 parts by weight, bisphenol A type epoxy resin (Okaka Shell Epoxy Co., Epicoat 10
01) 30 parts by weight, o-cresol novolac type epoxy resin (Sumitomo Chemical Co., Ltd., ESCN-195LB) 10 parts by weight, glycidyl amine type epoxy resin (Okaka Shell Epoxy Co., Epicoat 604) 20 parts by weight, as a curing agent 15 parts by weight of dicyandiamide, amorphous silica as an inorganic filler (Aerosil R-97 manufactured by Nippon Aerosil Co., Ltd.)
2) 5 parts by weight, alumina (UA-505, Showa Denko KK)
5) 20 parts by weight and 20 parts by weight of methyl carbitol as a solvent were stirred and mixed, and further sufficiently kneaded with a three-roll to obtain an adhesive composition. A 1% spherical silica spacer having a diameter of 5 μm was mixed with this adhesive composition to prepare a liquid crystal cell in the same manner as in Example 1. The evaluation results are as shown in Table 1.

[0024]

[Table 1]

[0025]

EFFECT OF THE INVENTION The sealing material for liquid crystal display device of the present invention exhibits good adhesiveness and excellent heat and humidity resistance.
When applied to a liquid crystal display element, a liquid crystal display element having excellent reliability can be provided.

Claims (5)

[Claims] 1. A one-pack adhesive composition containing an epoxy resin, a curing agent and an inorganic filler as main components, wherein the curing agent contains a liquid polybutadiene resin having an acid anhydride group in the molecule as an essential component. A sealant composition for a liquid crystal display device, comprising: 2. The sealing material composition for a liquid crystal display device according to claim 1, wherein the liquid polybutadiene resin having an acid anhydride group in the molecule is contained in an amount of 1% by weight or more based on all epoxy resins. 3. The liquid polybutadiene resin having an acid anhydride group in the molecule has a structure in which an acid anhydride group is added to a polybutadiene resin having an allyl group at a terminal, and has a number average molecular weight of 700 or more. Claim 1 characterized by the above.
Alternatively, the sealing material composition for liquid crystal display element according to the item 2. 4. The liquid polybutadiene resin having an acid anhydride group in the molecule has a maleic anhydride group, and the addition ratio thereof is 0.3 (mol / mol) or more with respect to the main chain polybutadiene. The sealant composition for liquid crystal display according to claim 1 or 2. 5. A liquid crystal display device using the sealant composition for a liquid crystal display device according to claim 1.