JP2582935B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a liquid crystal display device, and more particularly to preventing line-shaped lighting unevenness caused by static electricity in a manufacturing process.

(B) Conventional technology A liquid crystal display device has a structure as shown in FIG. A transparent electrode 3 patterned in a predetermined shape and an alignment film 4 covering the transparent electrode 3 are provided on the upper and lower glass substrates 2, and a liquid crystal material is injected between the two glass substrates. The peripheral part is sealed with a sealing material 6. To keep the distance between the liquid crystal cells constant, a spacer material 7
Are uniformly dispersed, and the distance between the liquid crystal cells is generally 4 to 30 μm. Finally, the polarizing plates 1 are arranged on both outer sides of the glass substrate, and the liquid crystal display cell is completed.

By the way, this polarizing plate has a laminated structure of an insulating film, and has the property of being easily charged with static electricity.
Incidentally, it is well known that when peeling off the protective film provided on the polarizing plate from the polarizing plate body, several hundreds to several thousand volts of static electricity are generated.

In a liquid crystal display device, as typified by the example of generation of static electricity accompanying the peeling of the protective film on the polarizing plate described above, in the manufacturing process, there are many opportunities to generate static charge and discharge. There has been a problem that a display irregularity of the liquid crystal display device due to the discharge, particularly a defect due to a linear lighting irregularity occurs.

(C) Problems to be Solved by the Invention As in the above-described example of the generation of static electricity due to the peeling of the protective film on the polarizing plate, when the electrostatic charge is generated outside the liquid crystal layer material, the charge of this charge is Correspondingly, an electric double layer is formed, and as a result, static electricity (potential difference) is also generated inside the liquid crystal layer material (inside the two glass substrates of the liquid crystal display device).

When the terminal portion of the liquid crystal display device comes into contact with a good electrical conductor such as a metal (that is, a material having a low specific resistance of deposition) in a state where the static electricity is charged in the liquid crystal display device, a discharge path is formed. The charge state of the alignment film (FIG. 3-4) and the spacer (FIG. 3-7) located on the transparent electrode of the liquid crystal cell in the region serving as the discharge path locally changes, and as a result, the liquid crystal display The threshold voltage of the device will change locally.
For this reason, traces (areas) of the discharge path are visually recognized as linear lighting unevenness, and there is a problem that the display quality of the liquid crystal display device is significantly deteriorated.

One solution to this problem is to dispose a conductive tape or the like at the terminal of the liquid crystal display device (FIG. 2-8).
It is known that the formation of a discharge path caused by the contact of a good electrical conductor such as a metal to a terminal portion is prevented by dispersing it over a wide area and dispersing it between many electrodes of a liquid crystal cell. Examples of the conductive tape include Cu7636R (trade name) manufactured by Sony Chemical Corporation.

However, the charging phenomenon and the discharging phenomenon from the terminal portion of the liquid crystal display device also occur in the process of connecting the liquid crystal display device to the driving circuit. Is difficult and troublesome, and it is difficult to actually use it. Further, this "conductive tape" is composed of a conductive layer / base film / adhesive layer, and has a major drawback that when the conductive tape is removed, a charging phenomenon and a discharging phenomenon occur due to peeling.

(D) Means for Solving the Problems According to the present invention, the conductive resin composition is provided in the terminal region of the liquid crystal display device, and the volume specific resistance of the conductive resin composition is 10 ² There is provided a liquid crystal display device characterized by being substantially in the range of Ωcm to 10 ⁸ Ωcm and not substantially changed in the heating step.

The terminal area of the liquid crystal display device according to the present invention is defined as a first region.
In FIG. 2 (cross-sectional view) and FIG.
Means

2 and 1, 1 is a polarizing plate, 2 is a glass substrate, 3 is a transparent electrode, 4 is an alignment film, 5 is a liquid crystal layer, 6
Is a sealing material and 7 is a spacer material. The conductive resin composition of the present invention is provided including the outside of the sealing material.

This arrangement is performed by applying a conductive resin composition (usually used as a paste). Coating can be performed according to a conventional method. The width of the coating is when the gap between the liquid crystal cells is about 4 μm to 10 μm (0.3 to 1 mm) ×
(10 × 10cm). The timing of the application is usually preferably after the liquid crystal layer is sealed.

The conductive resin composition of the present invention is adjusted so that its volume resistivity value is from 10 ² Ωcm to 10 ⁸ Ωcm. And
This resistance value does not substantially change even when subjected to the heat treatment in the manufacturing process of the liquid crystal cell.

Such a conductive resin composition is usually composed of a conductive substance and an organic binder, and a solvent is further used to form a paste.

Examples of the conductive substance include aromatic compounds that can be chemically oxidized and polymerized (for example, aromatic 5-membered ring compounds such as pyrrole, thiophene, and furan, and their substituted products, and aromatic hydrocarbons such as benzene, naphthalene, and anthracene). Conductive polymers obtained by oxidative polymerization, those obtained by coating a core material of an organic compound or an inorganic compound with these conductive polymers, and an organic electrolyte are used.

As the oxidizing agent used for chemically oxidatively polymerizing the aromatic compound, a conventionally known oxidizing agent can be used, and examples thereof include ferric chloride, cupric chloride, stannic chloride, molybdenum chloride, and chloride. Chlorides such as tungsten and ruthenium chloride; sulfates such as copper sulfate and ferric sulfate; oxides such as potassium dichromate, manganese oxide and lead oxide;
Beroxo acids such as ammonium persulfate, potassium persulfate, sodium hypochlorite, sodium chlorate and hydrogen peroxide; metals such as potassium tetrachloroplatinate (II), sodium tetrachlorovanadium (II) and sodium tetrachloroaurate Chloride; halogen such as iodine and bromine; The concentration of the oxidizing agent during the chemical oxidative polymerization can be appropriately selected from the range of 0.001 mol / to the saturation concentration, and is particularly preferably about 0.01 to 5.0 mol /.

The solvent used for chemically oxidatively polymerizing the aromatic compound is not particularly limited, and a solvent in which the aromatic compound is soluble may be used. For example, solvents such as water, acetonitrile, benzonitrile, nitrobenzene, methanol, ethanol, and tetrahydrofuran (THF) are used. The temperature and time for the polymerization may be arbitrarily selected depending on the type of the oxidizing agent and the solvent to be used and the desired volume resistivity, and are usually in the range of 0 to 100 ° C. for 10 minutes to 24 hours. The volume resistivity of the obtained conductive polymer is 1 × 10 ⁻¹ to 1 × 10 ⁵ Ωcm, more preferably 1 × 1 Ωcm.
0 ⁻¹ to 1 × 10 ³ Ωcm. That is, in order to obtain a conductive polymer having a volume resistivity of less than 10 ^-1 Ωcm, a stretching treatment or the like is required, which is not practical. On the other hand, when it is 10 ⁵ Ωcm or more, the conductivity is insufficient and the predetermined performance cannot be expressed.

The method of chemically oxidatively polymerizing the aromatic compound may be a commonly used method.For example, a method in which an oxidizing agent is dissolved in water, and a solution in which the aromatic compound is dissolved in an appropriate solvent as necessary are used. A method of adding is used. The conductive polymer obtained by the above method can be filtered off to remove the solvent, washed with water and / or washed with a solvent, and then isolated as a powder by ordinary means such as drying under reduced pressure.
Further, when an aromatic compound having a substituent is used,
A liquid conductive polymer can be obtained by the same operation as described above. Further, an organic or inorganic substance having at least a surface coated with a conductive polymer may be obtained, for example, by adsorbing / impregnating an oxidizing agent to polymer fine particles having an anionic functional group, and then adding the aromatic compound to obtain an aromatic compound. It can be obtained by a method of polymerizing a compound.

On the other hand, as the organic electrolyte, an organic sulfonate,
One or more selected from organic sulfates, salts of organic sulfates, salts of organic phosphates and salts of organic carboxylic acids can be used. As the kind of the salt, amines such as amine quaternary salts and ammonium salts, and metals such as sodium and potassium can be used.

 Specific examples of these organic electrolytes are shown below.

In organic sulfonic acid type and organic sulfuric acid (ester) type,
Dodecylsulfonic acid, dodecylbenzenesulfonic acid, p
-Toluenesulfonic acid, dimethylsulfuric acid, naphthalenesulfonic acid, amine salts of polystyrenesulfonic acid, and metal salts such as sodium and potassium can be used. Examples of such sulfonic acid products that are industrially produced include:
For example, Kusumoto Kasei's NACURE 155, NACURE 1051, N
ACUREX49-110, NACURE 3525, NACURE 2500X, NACURE 5
225 can be exemplified.

In the organic phosphoric acid system, amine salts, phosphoric acid, dodecyl phosphoric acid, di-dodecyl phosphoric acid, tri-dodecyl phosphoric acid, ammonium salts, metal salts such as sodium and potassium can be used. Examples of such phosphate-based amine salts that are industrially produced include NACURE4054 manufactured by Kusumoto Kasei Co., Ltd.
(All are trade names).

Furthermore, in the organic carboxylic acid system, acetic acid, maleic acid,
Amine salts such as polyacrylic acid and polymethacrylic acid, ammonium salts, and metal salts such as sodium and potassium can be used. These can be used alone or in combination of two or more.

Among the above, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid (eg, NAC
URE3525) is preferred.

As the organic binder used in the present invention, a commonly used coating binder resin can be used. For example, thermoplastic resins such as acrylic, vinyl, cellulose, and vinyl chloride / vinyl acetate copolymers,
Alternatively, a thermosetting resin as shown below can be used.

As the thermosetting resin, a known thermosetting resin such as a phenol resin, a urea resin, an amino resin, an alkyd resin, a silicon resin, a furan resin, a polyester resin, an epoxy resin, and a polyurethane resin can be used. Particularly, a phenol resin, an amino resin, and an epoxy resin are preferable.

Phenol resins include phenol, cresol,
Resins obtained by adding and condensing aldehydes such as formalin and furfural to those having a phenolic hydroxyl group such as xylesol, p-alkylphenol, chlorophenol, bisphenol A, phenolsulfonic acid and resorcin. Particularly, a resol type phenolic resin is preferable. When a novolak-type phenolic resin is used, it is preferable to use hexasamethylenediamine in combination.

As amino resins, urea, melamine, guanamine,
A resin obtained by addition condensation of formalin to an amino group such as aniline or sulfonamide can be mentioned, and an alkyl etherified melamine resin is preferable.

As a catalyst used for curing the melamine resin, when an amine salt of a strong acid such as p-toluenesulfonic acid or naphthalenesulfonic acid is used as a conductive substance, the dissociated sulfonic acid becomes a curing catalyst, so that no catalyst is used. When other amine salts are used, it is preferable to mix them by catalyzing an organic acid such as linoleic acid.

Examples of the alkyl etherified melamine resin include Super Beckamine L-105 manufactured by Dainippon Ink and Chemicals, Inc.
-60 ethyl melamine resin, Super Beckamine J-80
N of 2-60, J-840, L-117-60, L-127-60, L-109-50
-Butylated melamine resin, Super Beckamine G-821
−60, L−118−60, L−121−60, TD−139−60, L−110−60,
L-125-60, 47-508-60, L-145-60, L-116-70 iso-butylated melamine resins (all are trade names).

As the epoxy resin, diepoxides of bisphenols are preferable.For example, Epicoat 827,828,834,1001,1002,1004,1007,1009 manufactured by Shell Chemical Co., Ltd., Araldite GY-250,260,280,6071,608 manufactured by Ciba Geigy Co., Ltd.
4,6097,6099 and Epicron 810,1000,1010,3010 (all trade names) manufactured by Dainippon Ink and Chemicals, Inc.

Furthermore, as the epoxy resin, for example, a novolak epoxy resin having an average of three or more epoxy groups can be used. As these novolak epoxy resins,
Those having a molecular weight of 500 or more are suitable. The following are industrially produced with such a novolak epoxy resin, for example. Araldite EPN1138,1139, ECN1237,1280,1299 manufactured by Ciba Geigy Co., Ltd.
DEN431,438 manufactured by Dow Chemical Co., Ltd., Epicoat 152,154 manufactured by Shell Chemical Co., Ltd., EPR-0100, ERRB-0447, ERLB-0488 manufactured by Union Carbide, EOCN series manufactured by Nippon Kayaku Co., Ltd. If necessary, a curing catalyst or a diluent for an epoxy resin can be used. Examples of epoxy resin curing catalysts include aliphatic amines such as diethylene, triamine, triethylene, tetramine, tetraethylene, and pentamine; aromatic amines such as benzyldimethylamine, diaminodiphenylmethane and diaminodiphenylsulfone; maleic anhydride; and phthalic anhydride. Acid, hexahydrophthalic anhydride, methylnadic anhydride, p-dimethylaminobenzoaldehyde, 3
A fluoroboric acid / piperidine complex or the like can be used.

As a diluent for the epoxy resin, reactive diluents such as n-butyl glycidyl ether, lenoxide, phenyl glycidyl ether, styrene oxide, allyl glycidyl ether, glycidyl methacrylate, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and cellulose triacetate , Xylene, castor oil, pine oil and the like, and non-reactive diluents such as alkyl (nonyl) phenol, polyglycol, polysulfite, diallyl phthalate, ε-caprolactam and butyrolactone.

The aforementioned curable resins used in the present invention may be used alone or in combination of two or more. Furthermore, the mixing ratio of the organic binder in the present invention is 5 to 85 parts by weight, preferably 10 to 45 parts by weight with respect to 10 parts by weight of the conductive material, and when less than 5 parts by weight, the absolute amount of the organic binder is Insufficiency will result in poor fluidity of the resulting composition and poor printability. If the amount of the organic binder exceeds 85 parts by weight, on the contrary, the absolute amount of the conductive substance is insufficient, and the required conductivity cannot be obtained.

Examples of the solvent used for the conductive resin composition include benzene, toluene, hexanone, dioxane, solvent naphtha, industrial gasoline, cellosolve acetate, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, and dimethyl. Formamide, dimethylacetamide, and isopropanol,
Alcohols such as butanol, methyl ethyl ketone,
Ketones such as methyl perfluorobutyl ketone, amyl acetate,
Known ester-based solvents such as isoamyl acetate and butyl acetate are exemplified. The amount of the solvent varies depending on the type of the kneader, the kneading conditions and the type of the solvent. It is preferable to adjust the amount of the solvent so that the paste viscosity after kneading can be screen-printed.

In order to produce the conductive paste of the present invention, for example, a binder is dissolved in a solvent, and then a thermosetting resin and a conductive substance are added, and this is kneaded sufficiently evenly with a disper, a pole mill or three rolls. Prepare a conductive paste.

In addition, the conductive resin composition of the present invention has a volume specific resistance value substantially unchanged in heat treatment after application, and 10 ²
Ωcm to 10 ⁸ Ωcm. During this time, it has been confirmed that it is effective in preventing charging unevenness and in the problem of line leakage.

In addition, the measurement of the volume resistivity value of the conductive resin composition was performed by the following method.

That is, screen printing is performed on a glass-epoxy substrate, and the volume resistivity before and after the curing treatment is measured by a two-terminal method under a DC voltage of 20 V (at 26 ° C./60% RH atmosphere / Advantest Co., Ltd. R8340A digital ultra-high resistance meter).

 The volume specific resistance was calculated by the following equation.

Volume specific resistance (Ωcm) = R × t × W / L where R: resistance between electrodes (Ω), t: thickness of coating film (cm), W: width of coating film (cm), L : Distance between electrodes (cm).

(E) Embodiment Next, the present invention will be described with reference to embodiments, but the present invention is not limited thereto. Hereinafter, "parts" means parts by weight.

Reference Example 1 In 130 parts of methanol, 50 parts of ferric chloride (hexahydrate, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved. To this solution, 20 parts of pyrrole (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and reacted at -15 ° C for 5 hours. The obtained polypyrrole was filtered / washed with water and isolated and purified as a powder. The volume resistivity of the obtained polypyrrole was 1.2 × 10 ¹ Ωcm.

Reference Example 2 A liquid conductive polymer was obtained in the same manner as in Reference Example 1, except that 3-hexylthiophene was used instead of pyrrole. The volume resistivity of the obtained polythiophene was 6.5 × 10 ² Ωcm.

Example 1 2.2 parts of polyvinyl phenol as a binder, 4.0 parts of isobutylated melamine as a thermosetting resin, 0.5 parts of the polypyrrole obtained in Reference Example 1 as a conductive substance, and 0.3 parts of butyl carbitol as a solvent were weighed, and 3 pieces were weighed. The mixture was kneaded with a roll for 30 minutes.

The volume resistivity of the obtained conductive paste is 2.5 × 10 ³
Ωcm.

Next, a liquid crystal display panel in which this conductive paste was applied to a cell gap of 7.5 μm, an application width of 0.6 mm, a length of 150 mm, and 250 mm was manufactured, and subjected to a heat treatment at 120 ° C. for 1 minute. The volume resistivity of the conductive paste after heating is ~ 4 × 10 ³
Ωcm. The structure of the terminal part of the liquid crystal display panel is as follows: the width of the lead wire is 0.125 mm, the distance between the lead lines is 0.125 mm (that is, the pitch between the lines is 0.250 mm), and the line resistance in this case is insulated. Resistance is ~ 0.2MΩ (ie 200KΩ)
That was all. As a result, the effect of preventing charging unevenness was confirmed, and the problem of line leakage did not occur.

Example 2 Polythiophene obtained in Reference Example 2 as a conductive substance
Except for using the 0.9 substance, the same operation as in Example 1 was performed, and the volume resistivity of the obtained conductive paste was 4.5 × 1.
0 ⁶ Ωcm.

Next, a liquid crystal display panel in which the conductive paste was applied to a cell gap of 9.0 μm, an application width of 0.5 to 0.7 mm, a length of 150 mm and 240 mm was manufactured, and subjected to a heat treatment at 120 ° C. for 30 seconds. The volume resistivity value of the conductive paste after this heating is ~ 7 × 10
It was about ⁹ Ωcm. The structure of the terminal portion of the liquid crystal display panel is the same as that of the embodiment, and the lead line width is 0.125 mm, and the distance between the lead lines is 0.125 mm (that is, the line pitch is 0.250 mm). In the case, the line resistance was an insulation resistance of 100100 MΩ or more. As a result, the effect of preventing charging unevenness was confirmed, and the problem of line leakage did not occur.

Example 3 2.0 parts of polyvinylphenol (50% butyl carbitol solution) as a binder, 1.0 part of isobutylated melamine (60% butanol solution) as a thermosetting resin, and NACURE X49-110 (manufactured by Kusumoto Chemical Co., Ltd.) as a conductive substance , 0.5 part of dinonylnaphthalenedisulfonic acid amine salt) and 1.0 part of methyl ethyl ketone as a solvent were weighed and kneaded with a three-roll mill for 30 minutes.

Next, a liquid crystal display panel in which this conductive paste was applied to a cell gap of 7.5 μm, an application width of 0.8 mm, a length of 150 mm and a length of 250 mm was manufactured, and was subjected to a heat treatment at 100 ° C. for 1 minute. The volume resistivity of the conductive paste after this heating is ~ 1 × 10
It was ⁵ Ωcm. The structure of the terminal portion of the liquid crystal display panel has a lead line width of 0.125 mm, and the distance between the lead lines is also 0.125 mm (that is, the line pitch is 0.250 mm).
In this case, the line resistance was an insulation resistance of 44 MΩ or more.
As a result, the effect of preventing charging unevenness was confirmed, and the problem of line leakage did not occur.

Example 4 2.0 parts of polyvinylphenol (50% butyl carbitol solution) as a binder, 1.0 part of an acrylic resin (60% MEK solution), 0.43 part of linoleic acid, and 1.5 parts of sodium polystyrene sulfonate (molecular weight: 50,000) as a conductive substance
And 1.0 part of ethanol as a solvent were weighed and kneaded with a three-roll mill for 30 minutes.

The volume resistivity value of the obtained conductive paste is 2.7 × 17 ⁷
Ωcm. This was applied to a similar liquid crystal panel in the other embodiments, the heat treatment for 1 minute at 0.99 ° C., the volume resistivity of the resin became 9.4 × 17 ⁷ Ωcm. Also in this case, the effect of preventing charging unevenness was confirmed, and no problem of line-to-line leakage occurred.

(F) Effect of the Invention In the liquid crystal display device according to the present invention, after the liquid crystal layer is sealed with the sealing material, the specific conductive resin composition is applied to the terminal region including the outside of the sealing material. The composition has a moderate volume resistivity value and can prevent problems of charging unevenness and line-to-line leakage caused by contact of a metal or the like with a terminal portion in a manufacturing process.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display device according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a sectional view of a conventional liquid crystal display device. DESCRIPTION OF SYMBOLS 1 ... Polarizing plate, 2 ... Substrate, 3 ... Transparent electrode, 4 ... Alignment film, 5 ... Liquid crystal layer, 6 ... Sealing material, 7 ... Spacer material, 8 ... Application part of conductive paste .

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuhiko Hayashi Fuji, 4-1 Kinryuji Temple, Wakayama City, Wakayama Prefecture (72) Akira Yoshimatsu 2-11-3, Funatsu-cho, Wakayama City, Wakayama Prefecture (72) Akihiro Kondo, Inventor 3-59-59 Nishihama, Wakayama-shi, Wakayama (56) References JP-A-62-219662 (JP, A)

Claims (4)

(57) [Claims] A conductive resin composition is provided in a terminal region of a liquid crystal display device. The conductive resin composition has a volume resistivity of 10 ² Ωcm to 10 ⁸ Ωcm, and is substantially formed by a heating step. A liquid crystal display device characterized in that it does not change. 2. The apparatus according to claim 1, wherein the conductive resin composition contains a conductive substance and an organic binder as essential components. 3. The conductive material according to claim 2, wherein the conductive material is a conductive polymer obtained by oxidative polymerization of an oxidatively polymerizable aromatic compound or an organic or inorganic material coated with the conductive polymer. apparatus. 4. The device according to claim 2, wherein the conductive substance is an organic sulfonate.