JPH11246743A - Resin composition for sealing liquid crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin compsn. which imparts high reliability to liq. crystals adaptable to high-speed response and to liq. crystals adaptable to low-voltage driving by compounding an epoxy resin, a rubber, a curative, a coupling agent, a filter, and a solvent which dissolves the epoxy resin but does not dissolve the curative. SOLUTION: This compsn. comprises 100 pts.wt. epoxy resin (e.g. a bisphenol A epoxy resin) having at least two epoxy groups and a number average mol.wt. of 300-1,500, 0.5-25 pts.wt. acrylic rubber or silicone rubber having a particle size of 0.01-5 μm, 1-40 pts.wt. curative (e.g. a modified aliph. polyamine compd.), 0-5 pts.wt. coupling agent (e.g. γ-glycidoxypropyldiethoxysilane), 1-100 pts.wt. org. or inorg. filler, and 0-70 pts.wt. solvent which has a b.p. of 70-300 deg.C, is hydrophobic, and dissolves the epoxy resin but does not dissolve the curative. If necessary, the compsn. further contains a cure accelerator, a plasticizer, a levelling agent, an antifoaming agent, a reactive diluent, a pigment, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel liquid crystal encapsulating resin composition suitable for encapsulating a liquid crystal display device requiring high reliability that can be used in diversified display devices and severe use environments in recent years. It is about.

[0002]

2. Description of the Related Art In recent years, as a result of the rapid progress in computerization of personal computers, audio equipment, measuring instruments, color televisions and the like, display methods using liquid crystals have been widely adopted. This consumes very little power,
In addition to the features that the driving force (driving voltage) is small and that contrast can be sufficiently obtained even under sunlight, the size and weight can be reduced, and the price can be reduced. It is conceivable that the performance of the color technology has surpassed that of the CRT. Due to these various advantages, the application field of the liquid crystal display has been expanding more and more.

Accordingly, liquid crystal cell manufacturers are actively studying for improvement of productivity and higher quality. Among them, the reduction of the curing temperature and the shortening of the curing time of the liquid crystal encapsulant in the liquid crystal cell manufacturing process have become major issues for liquid crystal cell manufacturers. At the same time, there is a growing demand for a highly reliable seal material that enables a liquid crystal compatible with a high response speed and a liquid crystal compatible with a low voltage drive. Conventionally, as a liquid crystal sealing resin, a one-component heat-curable epoxy resin or an ultraviolet curable resin has been used. For example,
JP-A-57-137317 and JP-A-59-15
No. 7330 describes a one-component heat-curable epoxy resin.

[0004]

However, at present, these materials do not have sufficient performance to solve the above problems. That is, a one-component heat-curable epoxy resin requires a curing time of usually not less than 60 minutes at a temperature of 150 ° C.
When cured at a temperature of 30 ° C., it takes a long time of 2 hours or more before the required performance is developed. Further, there is no ultraviolet curable resin that can be completely cured at a level of several minutes, and all require after-curing, so that it is impossible to cure the resin in a short time. Further, the final cured product has low moisture resistance reliability and does not reach the performance of a one-component heat-curable epoxy resin.

[0005] In addition, with respect to the reliability of the liquid crystal, a problem of display availability after a high-temperature aging test is likely to occur. In other words, display errors due to poor alignment due to contamination of the alignment film of unreacted epoxy resin and the like, and display errors caused by sensitive reactivity between liquid crystal and trace impurities due to high response of the liquid crystal are likely to occur. A review from the front is urgently needed.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, in a one-part heat-curable epoxy resin-based sealant, a modified aliphatic polyamine is preferably used as a curing agent. And found that it is effective to select a solvent that does not dissolve the curing agent and dissolves the epoxy resin as a solvent, and has completed the present invention.

That is, the present invention relates to a low-temperature or high-temperature, short-time curable liquid crystal encapsulating resin composition containing an epoxy resin, a curing agent, a curing accelerator, a rubber, a coupling agent, a filler and a solvent as main components. By using a thermosetting liquid crystal encapsulating resin composition that dissolves an epoxy resin as a solvent and does not dissolve a curing agent and a curing accelerator, it can be heat-cured at a low temperature and in a short time, and further has a high response speed compatible liquid crystal. It is characterized by having high reliability for liquid crystals such as low-voltage drive-compatible liquid crystals, and in the resin composition, the solvent is hydrophobic, and the curing accelerator is a modified aliphatic polyamine. I do.

That is, the present invention provides the following (1) to (4). (1) A resin composition for liquid crystal encapsulation mainly comprising an epoxy resin, rubber, a curing agent (a curing accelerator if necessary), a coupling agent, a filler and a solvent, wherein the solvent dissolves the epoxy resin. A liquid crystal encapsulating resin composition, which does not dissolve a curing agent (and a curing accelerator).

(2) A liquid crystal encapsulating resin composition mainly composed of an epoxy resin, rubber, a curing agent (a curing accelerator if necessary), a coupling agent, a filler and a solvent. It is soluble and hardener (and hardener)
A resin composition for sealing a liquid crystal, characterized by using a solvent in which is insoluble.

(3) The resin composition for sealing a liquid crystal according to (1) or (2), wherein the solvent is hydrophobic.

(4) The resin composition for sealing a liquid crystal according to any one of (1) to (3), wherein the curing agent is a modified aliphatic polyamine.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The epoxy resin used in the present invention is a compound having two or more epoxy groups in a molecule. Specifically, for example, (I) addition condensation of bisphenol A, bisphenol F, phenol or cresol with formaldehyde Novolak resins, hydroxy compounds such as tetrahydroxyphenylmethane and resorcinol, amine compounds such as diaminodiphenylmethane, aniline, xylylenediamine, polyhydric alcohols such as glycerin and pentaerythritol, or carboxy compounds such as phthalic acid and hexahydrophthalic acid Polycondensation resin of a compound with an epihalohydrin such as epichlorohydrin and epibromohydrin, and a methyl epihalohydrin such as methyl epichlorohydrin; a resin obtained by halogenating the polycondensation resin; (II) epoxy Epoxidized fatty acids and their derivatives such as soybean oil, (III) an epoxidized polybutadiene, epoxidized diene polymers such as epoxidized polyisoprene, or, (IV) 3,4-epoxy -6
-Methylcyclohexylmethyl-3,4-epoxy-6
-Methylcyclohexane carbonate, bis (2,3-
Aliphatic epoxy resins such as epoxycyclopentyl) ether. These may be used alone or in combination of two or more. Among these, particularly preferred are those comprising the above-mentioned group (I), more particularly

The epoxy resin used in the present invention has an average molecular weight of usually 300 to 1500, preferably 400 to 100.
0. If the average molecular weight is less than 300, adhesion to the material constituting the cell is poor, and sufficient physical and chemical stability tends to be hardly obtained, and heat resistance tends to be reduced. Also, if this exceeds 1500, the adhesive surface after pre-drying has poor adhesion, so when the cell base material and the cell adherend after pre-drying are stacked,
Defects tend to occur, such as being easily displaced by an external impact, vibration, or the like, and being liable to deteriorate workability when applying a sealing material. The average molecular weight referred to here is a number average molecular weight, and when two or more epoxy resins are used,
It means their average number average molecular weight.

Specific examples of the curing agent for the epoxy resin used in the present invention include primary amine, secondary amine, tertiary amine curing agents, polyaminoamide curing agents, and acid and acid anhydride curing agents. A curing agent such as an agent, dicyandiamide, an organic acid dihydrazide, an imidazole, a Lewis acid or Bronsted acid salt, or a polymercaptan type can be used. Among them, a modified aliphatic polyamine is preferable. In particular, Fuji Cure FXE-1000 manufactured by Fuji Kasei Kogyo Co., Ltd.
(Trade name) and / or FXR-1030 (trade name)
Is preferred. Further, it is also possible to use the above-mentioned Fujicure in combination with another curing agent. If necessary, a curing accelerator can be used in combination. Known curing accelerators can be used in this case.

These modified aliphatic polyamine compounds are:
Acts as a curing agent for the epoxy resin, and when mixed with the epoxy resin, has good storage stability at room temperature, and can be used as a one-pack type epoxy resin after mixing. In addition, curing agents used in other one-pack type epoxy adhesives, such as dicyandiamide and its derivatives, boron trifluoride-amine complex, initiate a curing reaction at a relatively low temperature and have extremely high heat resistance. And a curability that imparts water resistance, and there is no generation of substances that adversely affect the liquid crystal.

The amount of the curing agent used in the present invention is 1 to 40 phr, preferably 1 to 40 phr, based on the epoxy resin.
Desirably, it is 0 to 20 phr. If 1 phr
If it is less than 30, the storage stability will be considerably improved, but the curing will be slow and the degree of crosslinking will not be sufficient, and the adhesiveness, moisture resistance, electric properties, and action with the liquid crystal will tend to be poor. If it exceeds 40 phr, the curability tends to be further improved, but the storage stability is extremely deteriorated, the water absorption rate is increased, and the electric characteristics tend to be deteriorated.
Liquid crystals tend to be adversely affected.

The rubber used in the present invention may be any rubber having a so-called sea / island structure in which rubber particles are dispersed in a resin layer after an epoxy-based sealing material is cured. good. Specific examples of the rubber include, for example, acrylic ester, silicone, conjugated diene, olefin, polyester, and urethane, and in particular, acrylic ester, silicone, conjugated diene, Is preferable, and an acrylic ester type and a silicone type are more preferable. These may be used alone or in combination.

As a method for dispersing the rubber particles, the rubber particles may be dispersed in an epoxy resin, or may be dissolved in the epoxy resin and then precipitated upon curing. A method of forming rubber particles in the presence of a graft copolymer with an epoxy resin or a graft copolymer with an epoxy resin may also be used. Preferably, a method of easily controlling the particle size of rubber, such as a method of generating rubber particles in the presence of a graft copolymer with an epoxy resin or a graft copolymer with an epoxy resin, is preferable. These methods are methods that have an interaction at the rubber / resin interface and are stably dispersed. If there is no interaction between the rubber and the resin interface, it is easy to aggregate after curing, and it is difficult to maintain the reliability of hardness. Further, when the rubber is appropriately crosslinked, the rubber particles are less likely to be deformed even by the stress caused by curing, which is even better.

The acrylic ester rubber includes a core /
There are methods using rubber particles obtained by drying the shell type emulsion, and those disclosed in JP-A-55-16053 or JP-A-55-21432. In terms of the viscosity of
The latter is preferred.

Examples of the silicone rubber include a method using silicone rubber fine particles, a method disclosed in JP-A-60-72957, a method disclosed in JP-A-170523, and a double bond to an epoxy resin. A method of reacting a hydrogen-containing silicone capable of reacting with the double bond to form a graft, and polymerizing a silicone rubber monomer in the presence of the graft, a method of introducing a double bond into an epoxy resin. A method of reacting the polymer with a vinyl group-containing silicone monomer to form a graft, and a method of polymerizing a silicone rubber monomer in the presence of the graft.

As the conjugated diene rubber, for example,
3-butadiene, 1,3-pentadiene, isoprene,
Monomers such as 1,3-hexadiene and chloroprene can be produced by polymerization or copolymerization, and commercially available products can be used. In particular, copolymers of butadiene having a carboxyl group at the end and acrylonitrile, copolymers of butadiene having an amino group at the end and acrylonitrile, etc. are dissolved in the epoxy resin, and the rubber particles are of a type in which the rubber precipitates upon curing. Easy to control. However, it is difficult to control the particle size, and the performance may be insufficient compared with the above two methods (acrylic ester rubber and silicon rubber).

The average particle diameter of the rubber used in the present invention is 0.01 to 5 μm, preferably 0.01 to 2 μm.
Rubber, which is capable of forming a so-called sea / island structure, which is dispersed by particles of If the average particle size is outside the above range,
The high reliability of the present invention is hardly obtained, and the performance tends to be easily deteriorated. The amount of rubber used is usually 0.5 to 2 parts by weight based on 100 parts by weight of epoxy resin, rubber and curing agent in total.
It is 5 parts by weight, preferably 2 to 20 parts by weight. If the amount is less than 0.5 part by weight, the adhesive strength in a wet atmosphere tends to be insufficient, and if it exceeds 25 parts by weight, the viscosity of the sealing resin composition increases and the Workability such as printability tends to decrease, and the adhesive surface after pre-drying tends to have poor adhesion and the like. One or more of these rubbers may be used.

The coupling agent used in the present invention includes:
Specifically, for example, (1) vinyl trichlorosilane,
Vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-
Vinylsilane-based coupling agents such as methacryloxypropyltrimethoxysilane, (2) β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-
Glycidylsilane coupling agents such as glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldiethoxysilane, (3) N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-
aminosilane-based coupling agents such as β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, (4) isopropyl triisostearoyl Titanate, isopropyltridodecylbenzenesulfonyl titanate, isopropyltris (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) Titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctylpyrophosphate)
G) titanate coupling agents such as oxyacetate titanate and tris (dioctyl pyrophosphate) ethylene titanate; (5) γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane; And other special silane coupling agents. These may be used alone or in combination of two or more. Among them, particularly preferable ones are those having good storage stability at room temperature when mixed with an epoxy resin as in (2), and the mixture can be used as a one-pack type epoxy resin.

The amount of these coupling agents varies greatly depending on the composition of the encapsulating resin composition used in the present invention, but generally ranges from 0 to 5 per 100 parts by weight of the resin composition.
Parts by weight are desirable. Basically, in the present invention, the use of a coupling agent is desirable for maintaining the performance, but the performance is sufficiently exhibited without adding it. If the amount is more than 5 parts by weight, the cohesive strength of the resin tends to decrease, and as a result, the adhesive strength and the reliability tend to decrease.

Examples of the filler used in the present invention include (1) carbonates such as calcium carbonate and magnesium carbonate, sulfates such as barium sulfate and magnesium sulfate, aluminum silicate and zirconium silicate. Silicate,
Iron oxide, titanium oxide, aluminum oxide (alumina),
Oxides such as zinc oxide and silicon dioxide, potassium titanate,
Inorganic fillers such as kaolin, talc, asbestos powder, quartz powder, mica, glass fiber, and (2) polyethylene powder, polypropylene powder, polyvinyl chloride powder, polystyrene powder,
Organic fillers such as polyvinyl acetate powder, polystyrene, vinyl acetate copolymer powder, polymethacrylate powder, polyurethane powder, polyester powder, urea resin powder, phenol resin powder, and epoxy resin powder.

The amount of these fillers varies greatly depending on the composition of the encapsulating resin composition used in the present invention, particularly on the kind of the filler itself.
1 to 100 parts by weight is desirable for 0 parts by weight. Generally, in the present invention, when the filler is less than 1 part by weight,
There is a tendency for defects such as poor coating workability and poor retention of the coated pattern. If it exceeds 100 parts by weight, coating by screen printing or the like tends to be hindered. When the filler is mixed, it is preferable to knead the mixture with a three-roll mill or the like to prevent clogging of the screen such as screen printing, and to use the mixture after making it fine.

The solvent used in the present invention has no hydrophilicity, that is, is hydrophobic and has a boiling point of 70 to 300.
° C is desirable. Specifically, for example, hydrocarbons such as n-heptane, n-octane, n-decane, cyclohexane, benzene, toluene, xylene, ethylbenzene, diethylbenzene, aminobenzene, naphthalene, pinene, carbon tetrachloride, ethylene chloride, 1,1,1-trichloroethane, 1,1,1,2-tetrachloroethane, hexachloroethane, trichloroethylene, tetrachloroethylene, 1,2,3-trichloropropane, butyl chloride, amyl chloride, 2-ethylhexyl chloride, ethylene bromide , Tetrabromoethane, chlorobenzene,
Halogenated hydrocarbons such as 1,2,4-trichlorobenzene and bromobenzene, fusel oil, n-butyl ether, n-hexyl ether, ethylphenyl ether;
Ethers and acetals such as 1,4-dioxane, trioxane, diethyl acetal and the like, ketones such as methyl ethyl ketone, methyl-n-butyl ketone, methyl-n-amyl ketone, acetonylacetone, isophorone, cyclohexanone, acetophenone, propyl formate and isobutyl formate Esters such as ethyl acetate, n-butyl acetate, benzyl acetate, isoamyl acetate, ethyl lactate, methyl benzoate, diethyl oxalate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, methyl cellosolve acetate, cellosolve acetate, Derivatives of polyhydric alcohols such as dibutyl cellosolve, propylene glycol diacetate, carbitol acetate, hexylene glycol, sulfur-containing solvents such as dimethyl sulfoxide, succinic dia Tate, glutaric acid diacetate, a diacetate of dibasic acids adipic acid diacetate.

In the present invention, when the boiling point of the solvent is lower than 70 ° C., the solvent is volatilized during the storage of the adhesive or during the operation of applying the adhesive, and the viscosity of the adhesive is increased. There is a tendency. When the boiling point is higher than 300 ° C., the pre-drying step requires a long time,
There is a risk that the solvent may remain in the applied adhesive and impair the performance of the sealing material in the cell, and the adhesive performance tends to be insufficient.

The reason for adding a solvent in the present invention is to impart fluidity to the adhesive and to give appropriate coating properties. Therefore, it is necessary to adjust the amount of the solvent to satisfy these conditions. Generally, the amount of the solvent is 0 to 70 parts by weight, preferably 5 to 4 parts by weight, per 100 parts by weight of the epoxy resin.
0 parts by weight is suitable. The solvent used may be one kind or a combination of two or more kinds.

As the solvent in the present invention, a solvent which basically dissolves the epoxy resin but does not dissolve the curing agent and the curing accelerator is used. That is, in the encapsulating resin composition of the present invention, the curing agent and the curing accelerator are not substantially dissolved in the epoxy resin, that is, are present in the form of fine particles. It melts only when the temperature is raised at the time of curing and acts as an original curing agent and a curing accelerator (that is, a latent curing agent). Therefore, when the encapsulating resin composition of the present invention is being stored, the curing agent and the like do not dissolve at normal temperature, so that it is extremely excellent in stability. However, when the solvent is not the solvent of the present invention, the curing agent and the curing accelerator are dissolved in the solvent used, and the reaction is started at that point, and the composition itself lacks stability.

In the present invention, if necessary, other known additives may be added as long as the effects of the present invention are not impaired. For example, various additives such as a curing accelerator, a pigment, a dye, a plasticizer, a leveling agent, an antifoaming agent, and a reactive diluent can be used as needed.

[0032]

The present invention will be described below in detail with reference to examples and comparative examples. In the following, “parts” and “%” are based on weight. The present invention is not limited to the following examples.

Examples 1 to 6 Various raw materials were mixed at the ratios shown in Table 1 using a mixer such as a Henschel mixer, Dalton mixer, or ball mill, and filled with three rolls made of ceramics. The mixture was kneaded until the particle size of the agent and the curing agent became 10 μm or less. Mixture 100
Parts and a spacer (diameter: 5 μm, milled fiber) were thoroughly mixed at room temperature. The obtained liquid crystal encapsulating resin composition, on a glass substrate provided with a transparent electrode and an alignment film,
The pattern was applied by a screen printing method. Next, 8
Precured (preliminary drying) at 0 ° C for 20 minutes, and cooled to room temperature. After bonding the other glass-coated substrate and pressing it with a pressing jig, 110 ° C. × 60 minutes and 150 ° C.
This was hardened for 5 minutes. Here, of the above patterns, those having an adhesion area of 10 mm × 10 mm were subjected to the measurement of the adhesive strength (surface tensile adhesive strength). On the other hand, for a 1-inch panel with a seal width of 1 mm, a biphenyl type liquid crystal is sealed in the obtained empty panel from a liquid crystal filling port, and the filling port is structured bond ES-281 (trade name, Mitsui Chemicals, Inc.). And a liquid crystal panel was created. The obtained liquid crystal panel was used for evaluation of electric characteristics. Table 3 shows the results of these evaluations.

Comparative Examples 1 to 6 Using the resin compositions of Comparative Examples shown in Table 2 in the same manner as in Examples, test pieces for adhesion test and electrical property test were obtained. About the obtained thing, it evaluated similarly to the Example and the result was shown in Table 4.

The evaluation of the liquid crystal encapsulating resin composition and the prepared test pieces were performed as follows. (1) Storage stability: 100 g of the encapsulating resin composition is 100
The mixture was placed in a polyethylene container for ml and left for about one month in an atmosphere of 5 ° C. and 20 ° C., respectively. The rate of increase in viscosity over time was measured. (2) Adhesive force: The surface tensile adhesive strength was measured immediately after the test piece was prepared and after the test piece was immersed in boiling water for 3.5 hours. (3) Electric characteristics: Immediately after the liquid crystal panel was prepared, and after leaving it in an environment of 80 ° C. × 95% RH for 1000 hours, the current value between the terminals was measured, and the rate of change was measured.

[0036]

[Table 1]

(Explanation of abbreviations) EP resin 1: bisphenol F / epichlorohydrin polycondensation type epoxy resin, average molecular weight 400, epoxy equivalent 190 EP resin 2: bisphenol A / epichlorohydrin polycondensation type epoxy resin, average molecular weight 900, epoxy equivalent 450 ADH : Adipic acid dihydrazide PGDA: Propylene glycol diacetate SGA: Mixture of dimethyl succinate, glutaric acid dimethyl ester and dimethyl adipic acid Main curing L: 110 ° C × 60 minutes Main curing H: 150 ° C × 5 minutes

[0038]

[Table 2]

(Explanation of Abbreviations) EP resin 1: bisphenol F / epichlorohydrin polycondensation type epoxy resin, average molecular weight 400, epoxy equivalent 190 EP resin 2: bisphenol A / epichlorohydrin polycondensation type epoxy resin, average molecular weight 900, epoxy equivalent 450 ADH : Adipic acid dihydrazide MC: Methyl carbitol NMP: N-methyl-2-pyrrolidone Main curing L: 110 ° C × 60 minutes Main curing H: 150 ° C × 5 minutes

[0040]

[Table 3] (Explanation of abbreviation symbols) ──: Viscosity cannot be measured due to high viscosity

[0041]

By using the resin composition of the present invention, it is possible to produce a highly reliable liquid crystal display panel at a low temperature and in a short time, and at the same time, to save energy in the manufacturing process of the liquid crystal display panel. It has become possible to contribute to cost reduction. That is, it is possible to provide a sealing material that can be heat-cured at a low temperature and in a short time and that has high reliability for liquid crystals such as a liquid crystal corresponding to a high response speed and a liquid crystal corresponding to a low voltage drive. Further, according to the resin composition of the present invention, it was possible to solve the problem of display availability after a high-temperature aging test as reliability against liquid crystal.

Claims (4)

[Claims] 1. A liquid crystal encapsulating resin composition comprising an epoxy resin, a rubber, a curing agent (a curing accelerator if necessary), a coupling agent, a filler and a solvent, wherein the solvent is an epoxy resin. And a curing agent (and a curing accelerator) are not dissolved therein. 2. A liquid crystal encapsulating resin composition mainly comprising an epoxy resin, rubber, a curing agent (a curing accelerator if necessary), a coupling agent, a filler and a solvent, wherein the epoxy resin is soluble. And a solvent in which a curing agent (and a curing accelerator) is insoluble, is used. 3. The liquid crystal sealing resin composition according to claim 1, wherein the solvent is hydrophobic. 4. The resin composition for sealing a liquid crystal according to claim 1, wherein the curing agent is a modified aliphatic polyamine.