JPH11109384A - Sealing and sealing materials for liquid crystal cells - Google Patents

Abstract

(57) [Problem] To provide a UV-curable sealing material and a sealing material for a liquid crystal cell which form a cured layer having excellent adhesion, moisture resistance and flexibility. [Constitution] (A) Epoxy acrylate oligomer
100 parts by weight (B) Epoxy resin liquid at room temperature
5 to 120 parts by weight (C) polymerizable unsaturated monomer
0 to 80 parts by weight (D) silane coupling agent
1 to 50 parts by weight and (E) a photopolymerization initiator
An ultraviolet-curable sealing material or sealing material for a liquid crystal cell comprising 0.1 to 10 parts by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to adhesiveness, moisture resistance,
The present invention relates to an ultraviolet-curable sealing material and a sealing material for a liquid crystal cell which form a cured layer having excellent flexibility and the like.

[0002]

2. Description of the Related Art In a liquid crystal cell, liquid crystal is usually injected into a gap between a pair of electrode substrates whose periphery is surrounded by a sealing material layer from an injection hole formed by a cut in the sealing material layer, and then the injection hole is sealed. It is manufactured by sealing with a material.

[0003] Conventionally, organic materials, particularly two-pack type epoxy resin compositions and one-pack type epoxy resin compositions, have been mainly used as seal materials.

However, the two-pack type epoxy resin composition has a problem that the pot life is short and the viscosity tends to increase, so that it has to be prepared for each lot, and the production efficiency is poor. On the other hand, the one-pack type epoxy resin composition is 150 to 20.
Since it is necessary to heat at a high temperature of 0 ° C. for several tens of minutes, the production efficiency is still insufficient.

Conventionally, two-pack type epoxy resin compositions and ultraviolet-curable resin compositions have been mainly used as sealing materials.

However, the production efficiency of the two-pack type epoxy resin composition is poor as described for the sealing material, while the ultraviolet-curable resin composition has insufficient adhesion to the electrode substrate and moisture resistance. Also, there is a problem that distortion of a cell gap due to curing shrinkage, peeling, and the like are likely to occur.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and is characterized in that a UV-curable sealing material or sealing material is cured by UV irradiation in a short time at room temperature. It is an object of the present invention to provide a sealing material and a sealing material which form a cured layer excellent in adhesion, moisture resistance, flexibility and the like while utilizing the above.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, an epoxy resin and a silane coupling agent were added to an ultraviolet-curable composition containing an epoxy acrylate oligomer as a main component. It has been found that the above objects can be achieved by blending, and the present invention has been achieved.

That is, the present invention relates to (A) 100 parts by weight of an epoxy acrylate oligomer, (B) 5 to 120 parts by weight of an epoxy resin which is liquid at room temperature, (C) 0 to 80 parts by weight of a polymerizable unsaturated monomer, (D) ) A silane coupling agent of 1 to 50 parts by weight, and (E) a photopolymerization initiator of 0.1 to 10 parts by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The composition of a UV-curable sealing material and a sealing material for a liquid crystal cell of the present invention will be described below.

The epoxy acrylate oligomer (hereinafter referred to as "component (A)") used in the present invention is produced by reacting a polyepoxide with a stoichiometric equivalent of acrylic acid or methacrylic acid. As the polyepoxide, a conventionally known polyepoxide having two or more epoxy groups can be used, and specifically, bisphenol A,
Bisphenol-type polyepoxide obtained by reacting epichlorohydrin with bisphenol F, etc .; Novolak-type polyepoxide obtained by reacting epichlorohydrin with a novolak resin; Ring obtained by epoxidizing the reaction product of butadiene with crotonaldehyde with peracetic acid Representative examples include, but are not limited to, formula aliphatic polyepoxides.

The epoxy acrylate oligomer also comprises
For example, it may be a modified ethylene oxide.

The epoxy acrylate oligomer is preferably liquid at room temperature, but any solid can be used as long as it is soluble in the polymerizable unsaturated monomer described below.

The epoxy resin which is liquid at room temperature (hereinafter referred to as component (B)) used in the present invention imparts flexibility to the sealing material and the sealing material, and has good follow-up properties to some extent of expansion and contraction of the electrode substrate. It is blended to improve the impact resistance, and usually has an epoxy equivalent of 172 to 226, preferably 172 to 190.

Specifically, bisphenol-type epoxy resins such as bisphenol A-type epoxy resin and bisphenol F-type epoxy resin, novolak-type epoxy resins such as phenol novolak-type epoxy resin, ortho-cresol novolak-type epoxy resin, and cycloaliphatic epoxy resin,
Heterocyclic epoxy resins are typical examples.

The polymerizable unsaturated monomer (hereinafter referred to as "component (C)") used in the present invention is compounded to improve coating workability and sealing workability and to improve various physical and chemical strengths. And a monomer having at least one, and preferably two to three, polymerizable unsaturated groups.

Specifically, it has three polymerizable unsaturated groups such as trimethylolpropane tri (meth) acrylate, trimethylolpropane-ethylene oxide-added tri (meth) acrylate, and glycerin-propylene oxide-added tri (meth) acrylate. Monomers, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) A) a monomer having two polymerizable unsaturated groups, such as acrylate and triethylene glycol di (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Typical examples include monomers having one polymerizable unsaturated group such as dipropylene glycol mono (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate.

The silane coupling agent (hereinafter referred to as "component (D)") used in the present invention is compounded to improve the adhesion to the electrode substrate.

Specific examples of the component (D) include vinylsilanes such as vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane and vinyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane and the like. Acrylic silane, β-
Epoxysilanes such as (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltri Aminosilanes such as methoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and other γ-
Typical examples include silane coupling agents such as mercaptopropyltrimethoxysilane and γ-chloropropyltrimethoxysilane. In particular, in the present invention, vinylsilane-based and acrylsilane-based polymers containing a polymerizable unsaturated group are preferred because not only the adhesion is improved, but also the moisture resistance and the like are improved because a dense layer is formed.

The photopolymerization initiator (hereinafter referred to as the component (E)) used in the present invention generates free radicals by the energy of ultraviolet rays and has the components (A), (C) and a polymerizable unsaturated group. It is compounded to radically polymerize the component (D) and cure the sealing material and the sealing material.

As the component (E), various known compounds can be used without any particular limitation.
Representative examples include benzoin, benzophenone, acetophenone, and derivatives thereof such as esters and ethers.

The sealing material and the sealing material of the present invention contain the components (A), (B), (C), (D) and (E) described above. The component (B) is suitably used in an amount of 5 to 120 parts by weight, preferably 10 to 100 parts by weight, per 100 parts by weight of the component (A).
The component (C) is suitably used in an amount of 0 to 80 parts by weight, preferably 5 to 70 parts by weight, and the component (D) is suitably used in an amount of 1 to 50 parts by weight, preferably 10 to 30 parts by weight. The component (E) is suitably used in an amount of 0.1 to 10 parts by weight, preferably 1 to 7 parts by weight.

If the component (B) is less than the above range, the flexibility is deteriorated, and the followability to the electrode substrate, the impact resistance and the like are reduced. Any of these methods is not preferable because the chemical strength is deteriorated.

The component (C) is not necessarily required to be added if the component (A) is liquid at room temperature, but is preferably added to improve workability. However, when the amount is excessive, the viscosity becomes too low, so that it is difficult to form a normal sealing material layer and a sealing material layer, and the shrinkage at the time of curing becomes large, making it brittle.

If the amount of the component (D) is less than the above range, the adhesion becomes insufficient. If the amount is too large, the effect of improving the adhesion cannot be obtained, and it is not economical.

If the amount of the component (E) is less than the above range, a sufficient cured layer cannot be formed by short-time irradiation with ultraviolet light, and if the amount is too large, the electrode substrate is likely to be adversely affected.

The sealing material and the sealing material of the present invention can be obtained by the above (A)
In addition to the components (E) to (E), if necessary, it is also possible to incorporate additives such as light-transmitting materials such as transparent glass beads and resin beads, extender pigments, solvents, and thixotropic materials. In addition, a spacer such as glass beads, glass fiber, or plastic beads for holding the pair of electrode base materials at a constant gap may be included in the sealing material.

As a method of forming a seal layer using the seal material of the present invention, for example, a method of forming a seal layer around one side of an electrode substrate is used.
Or 4 to 3 times the cell gap (electrode substrate gap) by screen printing or using a dispenser, leaving a cut (injection hole) at 4 places, if necessary After putting in a drying oven to evaporate the solvent, cover the other substrate, apply pressure to the desired cell gap thickness, and then irradiate ultraviolet rays to cure the sealing material to form a cured sealing layer. .

It is appropriate to irradiate ultraviolet rays for several seconds to several tens of seconds with a mercury lamp, metal halide lamp, chemical lamp or the like of about 1 to 3 kW.

As a method for sealing an injection hole by using the sealing material of the present invention, for example, after injecting liquid crystal from the injection hole into a liquid crystal cell, the sealing material is applied to the injection hole, and sealed. The sealing material is cured by irradiating ultraviolet rays only in the vicinity of the injection hole through the mask in the same manner as in the case of the sealing material.

[0031]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples, "parts" are shown on a weight basis.

Examples 1 to 3 and Comparative Examples 1 and 2 (sealant): The compositions shown in Table 1 were kneaded with a three-roll mill, and 100 parts of the kneaded material was filled with a spacer 0 made of a 6 μm diameter milled fiber. 0.5 part was sufficiently mixed at room temperature to prepare a sealing material containing a spacer.

[0033]

[Table 1] Note: Note 1) Bisphenol A type polyepoxide-diacrylate (average molecular weight 1100) Note 2) Liquid bisphenol A type epoxy resin with an epoxy equivalent of 184 to 194 Note 3) "Aerosil # 200" (trade name of Nippon Aerosil Co., Ltd.) 4 to 5 and Comparative Examples 3 to 4 (sealing material): The compositions shown in Table 2 were kneaded with a three-roll mill to prepare a sealing material.

[0034]

[Table 2] Remarks: Note 1), Note 2), Note 3) are the same as Table 1.

The following methods were used to evaluate the performance of the sealing materials obtained in Examples 1 to 3 and Comparative Examples 1 and 2, and the sealing materials obtained in Examples 4 to 5 and Comparative Examples 3 and 4. , A liquid crystal cell was manufactured, and adhesion and moisture resistance tests were performed.
It was shown to.

A sealing material containing a spacer is screen-printed (325 mesh) on a glass substrate with a transparent electrode (periphery) while leaving a liquid crystal injection hole, and a second glass substrate with a transparent electrode is bonded to the glass substrate. After pressing with a butterfly clip, a metal halide lamp (1.5 kW) was used to irradiate ultraviolet rays from a position at a lamp height of 10 cm for 60 seconds.

After injecting the biphenyl-type liquid crystal into the obtained empty cell from the injection hole, the injection hole was sealed with a sealing material, and irradiated with ultraviolet rays for 30 seconds in the same manner as in the case of the sealing material to be cured.

The obtained liquid crystal cell was evaluated as follows. <Adhesion Test> The liquid crystal cell was left in an environment of 80 ° C. × 95% RH for 200 hours, and the room was left naturally for 10 hours as one cycle. After a 10-cycle test, the cell was peeled off using a knife.

：: No peeling Δ: Slightly peeling
×: Peeling somewhat easy <Moisture resistance test> After leaving the liquid crystal cell in an environment of 80 ° C. × 95% RH for 1000 hours, a rectangular wave of 5 V, 50 Hz, and a duty of 1/2 was applied between the terminals. Reliability was determined based on the rate of change.

：: small fluctuation (current value is less than twice the initial value) and good reliability Δ: slight fluctuation (current value is 2 to 3 times the initial value), reliability is somewhat poor ×: large fluctuation ( The current value exceeds 3 times the initial value), poor reliability

[0041]

[Table 3] As is clear from Table 3, the liquid crystal cells using the sealing material of the present invention of Examples 1 to 3 and the sealing material of the present invention of Examples 4 to 5 have good adhesiveness and have a high current value under a high temperature and high humidity environment. Was small, the reliability was good, and the moisture resistance was excellent.

On the other hand, the liquid crystal cells using the sealing material of Comparative Example 1 containing no silane coupling agent and the sealing material of Comparative Example 3 had poor adhesion and moisture resistance.

Comparative Example 2 not containing an epoxy resin
The liquid crystal cell using the sealing material of Comparative Example 4 and the sealing material of Comparative Example 4
Adhesion and moisture resistance were slightly inferior. This is probably because the sealing material layer and the sealing material layer hardly follow the expansion and contraction of the glass substrate.

[0044]

The sealing material and the sealing material for a liquid crystal cell of the present invention are of an ultraviolet curing type, and are cured by ultraviolet irradiation in a short time at room temperature, and the resulting cured layer has adhesion, moisture resistance, Because of its excellent flexibility and the like, a highly reliable liquid crystal cell can be obtained.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masaharu Yamazaki 1920-1 Usaba, Otawara-shi, Tochigi (72) Inventor Yoshihisa Nagashima 462-1 Teradana, Hiratsuka-shi, Kanagawa

Claims (2)

[Claims] (A) 100 parts by weight of an epoxy acrylate oligomer; (B) 5 to 120 parts by weight of an epoxy resin which is liquid at room temperature; (C) 0 to 80 parts by weight of a polymerizable unsaturated monomer; (D) silane coupling. An ultraviolet-curable sealing material or a sealing material for a liquid crystal cell, comprising 1 to 50 parts by weight of an agent and 0.1 to 10 parts by weight of (E) a photopolymerization initiator. 2. The ultraviolet-curable sealing material or sealing material for a liquid crystal cell according to claim 1, wherein the silane coupling agent contains a polymerizable unsaturated group.