JPH05241173A - Transparent conductive electrode for liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain an electrode for liquid crystal display excellent in electrode flatness which enables high-quality display by forming a solvent-resistant layer/ air permeation-resistant layer comprising metal nitride or metal oxide on at least one surface of a transparent sheet and then laminating a transparent conductive layer thereon. CONSTITUTION:A solvent-resistant layer/air permeation-resistant layer comprising metal nitride or metal oxide is formed on at least one surface of a transparent sheet. This transparent sheet consists of a resin selected from polycarbonate resin, polyethersulfone resin, polyallylate resin, and amorphous polyolefin resin. Further, a transparent conductive layer is formed thereon. As for the metal nitride, nitrides of Al, Si, Ti, Ta, Zr, Nb, Mo, W, etc., are used, and nitrides of Al, Si or AlSi are preferable and SiN and AlSiN, nitrides of Si and AlSi, are more preferable. As for the metal oxide, oxides of Al, Si, Ti, Zr, Ta, etc., are preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large and lightweight liquid crystal display material using a plastic substrate. More specifically, the present invention relates to an electrode substrate for a liquid crystal display, which is capable of high-quality display with excellent electrode flatness.

[0002]

2. Description of the Related Art As a liquid crystal display electrode substrate, a glass material is used for various reasons. However, as the demand for weight reduction has increased, the thickness of glass substrates used has become less than 1 mm, which may cause damage such as damage in the process, damage during use as large-sized displays, and display quality due to bending. Decrease is an issue for improvement.

As a means of reducing the possibility of breakage and reducing the weight, attempts have been made to replace the glass with a sheet of an optically isotropic organic material. In this case, in order to reduce the water permeability and oxygen permeability of the optically isotropic organic material, and to impart solvent resistance to various organic solvents used in the liquid crystal cell manufacturing process, In order to impart liquid crystal material resistance, a means for coating and laminating an organic material having various barrier properties on the surface has been taken (for example, JP-A-60-6982).

However, when a coating layer is provided and a transparent electrode is further laminated on the coating layer to form a display electrode for liquid crystal, the surface property is disturbed by the coating (large undulation,
There is a problem that the surface quality of the electrode surface is disturbed due to fine coating unevenness and the display quality is degraded. Particularly, in STN display which requires a fine surface uniformity, there is a problem in that the unevenness of the surface property interferes with the uniform alignment of the liquid crystal and remarkably deteriorates the display quality.

[0005]

The present invention has been made in view of the present circumstances. That is, by forming a surface layer having a high barrier property without using a method of disturbing the surface property such as coating, it is possible to provide an electrode for liquid crystal display which is excellent in display quality, is lightweight and does not break, and is an excellent liquid crystal display panel which has never existed before. It was made to be able to create.

[0006]

The above object can be achieved by the present invention described below. That is, the transparent conductive liquid crystal display electrode of the present invention comprises a metal nitride on at least one surface of a transparent sheet made of a resin selected from polycarbonate resin, polyether sulfone resin, polyarylate resin and amorphous polyolefin resin. It is characterized in that a solvent resistant layer / air permeable resistant layer composed of a substance or a metal oxide is formed, and a transparent conductive layer is further laminated thereon, which will be described in detail below.

As the transparent sheet made of resin used for the substrate, a sheet having high optical isotropy can be used. As a measure of optical isotropy, a retardation value is used, for example, in the visible light range (400
To 800 nm) and preferably 30 nm or less,
In the case of performing more precise display, etc., it is preferably 20 nm or less. As the resin used, a polycarbonate resin, a polyether sulfone resin, a polyarylate resin and an amorphous polyolefin resin are preferably used.

As a method for molding the transparent sheet, a known method such as heat-melt extrusion molding or solution cast molding can be used. At the time of molding, it is preferable to make a special effort so as to maintain the uniformity of the surface, and such a material should be selected when purchasing. The thickness of the transparent sheet used is arbitrary, but from the viewpoint of visibility as a liquid crystal display, it is 2 mm or less, and when the display is desired to be used for a flexible display, the thickness is 500 μm or less. preferable.

The surface property of the transparent sheet must be similar to that of glass for liquid crystal displays. For example, roughness (Raughness) Ra is 20 to 30 nm, and flatness (Warp Type) is used.
Is less than 500 μm, and Ripple Type is 0.2 to 0.3 for TN and ferroelectric liquid crystal display.
It is preferably not more than μm, and in the case of STN display, it is preferably not more than 0.05 μm.

Since the numerical values of the surface roughness often differ depending on the measuring method and the difference between the instruments, the above numerical values are only a guide.

A metal nitride or a metal oxide is preferably used as the solvent resistant layer / air permeable resistant layer formed on at least one surface of such a transparent sheet. Such a metal nitride or a metal oxide is preferable as a method capable of forming a vacuum thin film forming method such as CVD or sputtering without disturbing the surface property of the transparent sheet. In general, the vacuum thin film forming method is a method that does not roughen the surface of the substrate as compared with the wet coating method used for coating organic paints, but it particularly minimizes plasma damage and causes abnormalities such as protrusions on the surface. It is necessary to set thin film forming conditions that are less likely to cause such problems, and it is necessary to optimize the conditions according to the conditions of film forming equipment.

Metal nitrides include Al, Si, Ti,
Ta, Zr, Nb, Mo, W and the like are preferable, but A is particularly preferable in terms of easiness of formation on an organic sheet and transparency.
l, Si or AlSi nitrides are preferred, with Si and AlSi nitrides SiN and AlSiN being most preferred.

As the metal oxide, Al, Si, Ti,
Oxides such as Zr and Ta are preferably used. It is of course possible to use mixed oxides of these metals.

In the case of sputtering, for example, in the case of sputtering, these metal nitrides or metal oxides are targeted at the metal or metal nitride or metal oxide used, and in the case of nitride, a mixed gas of Ar and N ₂ is used. In the case of an oxide, it can be formed by a high frequency magnetron sputtering method or a direct current magnetron sputtering method using a mixed gas of Ar and O ₂ .

A vacuum deposition method, a CVD method or the like can be used, but an optimum process may be selected from the viewpoint of the uniformity of the thin film and the adhesiveness.

As a pretreatment for forming such a vacuum thin film, the substrate can be treated by using a physical means such as ion bombardment treatment or plasma etching treatment to improve the adhesiveness. In this case as well, the surface of the transparent sheet of the substrate is treated. It is necessary to set conditions that do not disturb the sex as much as possible.

Further, particularly when defects such as pinholes are likely to occur, the defects can be minimized by forming the metal nitride layer or the metal oxide layer by a process divided into two or more times. In this case, stacking of nitride / nitride, oxide / nitride, oxide / oxide, nitride / oxide, etc. is also possible.

However, defects such as pinholes are often caused by the inclusion of foreign matter such as dust and contamination. Therefore, it is possible to prevent this by thoroughly cleaning the process, removing static electricity, and cleaning the substrate. is important.

The film thickness of the metal nitride layer or the metal oxide layer is preferably in the range where the function of the solvent resistant layer / gas permeable resistant layer is satisfied and the coloration due to interference is minimized, generally 10 nm to 200 nm. The range of is preferably used. From an optical point of view, the thickness of the formed thin film varies depending on the refractive index of the formed thin film. Therefore, it is necessary to set the upper limit of the film thickness depending on the intended use.

A transparent conductive layer is laminated on the solvent resistant layer / air permeable resistant layer. The transparent conductive layer is made of In ₂ O 3.
A mixed metal oxide such as ₃ · SnO ₂ , ZnO · Al ₂ O ₃ or a metal thin film of Au, Ag, Cu or an alloy thin film thereof can be used. It is also possible to use, for example, a laminated thin film of a metal oxide thin film and a metal thin film or an alloy thin film.

Such a transparent conductive thin film layer can be formed by a known means by a vacuum thin film forming method such as sputtering or vacuum deposition.

The surface resistance of the transparent conductive thin film layer is 5
A value of 00Ω / □ or less, preferably 300Ω / □ or less is used.

According to the above description, the solvent resistant layer / permeation resistant layer made of metal nitride or metal oxide is formed on at least one surface of the transparent sheet, and the transparent conductive layer is further laminated. It is believed that the transparent conductive liquid crystal display electrode has been clarified.

In the present invention, when the solvent resistant layer / air permeable resistant layer / transparent conductive layer is formed on one surface, a metal nitride or a metal is further formed on the other surface of the transparent sheet, if necessary. It is also possible to improve the solvent resistance / permeability of the liquid crystal display electrode by forming only the solvent resistant layer / permeation resistant layer made of an oxide and to improve the life of the display. In this case, since the one surface above is on the opposite side of the display electrode, some surface irregularity is allowed. Therefore, the organic resin layer should be formed by a wet coating method using an organic resin or the like. It is also possible to laminate and laminate optically isotropic film-like materials having barrier properties.

As the Yuki resin used, the oxygen permeability (ASTMD-1434-75
30 cc / 24 hr · m ² · atm or less is preferable, and for example, a polymer containing 50 mol% or more of an acrylonitrile component, a vinyl alcohol component or a vinylidene halide component is preferably used. The thickness of the air-permeable resin layer is preferably in the range of 1 to 50 μm from the viewpoint of characteristics. If necessary, an undercoat layer may be provided between the air-permeable resin layer and the substrate for the purpose of improving the adhesive force.

Further, a cured crosslinkable resin layer may be laminated for the purpose of improving surface hardness and solvent resistance. As such a crosslinkable resin cured product layer, a crosslinkable resin selected from a phenoxy ether type crosslinkable resin, an epoxy resin, an acrylic resin, a melamine resin, a phenol resin, a urethane resin or the like can be appropriately used.

The organic resin layer formed by these coatings is
It is formed for the purpose of imparting a solvent resistant / air permeable resistant layer to the transparent sheet of the substrate. In addition, since these organic resin layers are laminated on the surface opposite to the surface on which the transparent electrode is formed, they do not have a direct function for a liquid crystal display. Since it is directly viewed through the resin layer, it is necessary to manage the coating process so as to minimize the film thickness unevenness caused by coating unevenness, foreign matter defects caused by contamination, and visual defects from the viewpoint of maintaining display quality. There is.

Further, since the liquid crystal manufacturing process is extremely sensitive to static electricity, an antistatic agent or the like can be contained in the resin layer. Further, in order to facilitate the handling in the process, a known lubricant such as colloidal silica may be appropriately added.

[0029]

[Use of transparent conductive liquid crystal display electrode] The transparent electrode of the present invention can be used as a display electrode having excellent solvent resistance / air resistance.

For liquid crystal applications, not only TN type and particularly STN type which requires surface smoothness but also polymer dispersed type liquid crystal can be used.

By using the electrode of the present invention,
It is possible to form a panel having excellent visibility as a flexible display body, and it is possible to attach it to a curved surface.

Further, it can be used as an electrode of an organic dispersion type electroluminescence display body, and is not limited to this, and can be applied as a field effect type display body or a current injection type display body.

It can be suitably applied not only as a display electrode but also as an electrode material for a touch panel or the like.

Next, the present invention will be described with reference to examples.

[0035]

Example 1 Thickness 90 μm, Retardation value 15 n
A nitride film of Al and Si was formed on both sides of a polycarbonate film of m (manufactured by Tsutsunaka Plastic Industry Co., Ltd.).

The Al and Si nitride film is an AlSi alloy (A
1 / Si = 30/70) as a target (manufactured by Kojundo Chemical Laboratory Co., Ltd.) using an RF magnetron sputtering device and introducing gas Ar / N ₂ = 6/4 mixed gas at a pressure of 2 × 10 ⁻³ Torr. Was formed by reactive sputtering.

The Al and Si nitride film (hereinafter referred to as the AlSiN film) had a film thickness of 80 nm and had a refractive index of 2.1 and was extremely transparent.

A transparent conductive layer made of ITO was subsequently formed on one side of a polycarbonate film having AlSiN formed on both sides.

The transparent conductive layer made of ITO was subjected to DC magnetron sputtering by targeting an ITO (indium tin oxide) press-molded product (filling ratio 90%, Mitsui Mining & Smelting Co., Ltd., In / Sn = 9/1). Formed.

It was formed by reactive sputtering at a pressure of 5 × 10 ^-3 Torr with a mixed gas of introduced gas Ar / O ₂ = 99/1.

The film thickness of the obtained transparent conductive layer made of ITO was 25 nm, and the surface resistance was 160 Ω / □.

The transmittance of the obtained laminated sheet is 550 nm.
Was 84%.

An immersion test was carried out for 30 minutes at room temperature in two kinds of solvents, N-methylpyrrolidone and γ-butyl lactone, so that the solvent did not adhere to the end surface of the transparent sheet, but no visible defects occurred. There wasn't. Further, the obtained transparent conductive liquid crystal display electrode was subjected to a moisture permeability test by a cup method (according to JIS Z 0208) and had a good barrier property of 1/100 or less of that of the polycarbonate film used as the substrate.

Furthermore, the surface condition of the ITO transparent conductive layer was observed with a surface roughness meter (α-step) and a differential interference microscope (manufactured by Nikon Corporation), but almost all of the surface condition of the polycarbonate film original fabric was maintained. It was

Claims (4)

[Claims] 1. A solvent resistant layer made of metal nitride or metal oxide on at least one surface of a transparent sheet made of a resin selected from polycarbonate resin, polyether sulfone resin, polyarylate resin and amorphous polyolefin resin. / A transparent conductive liquid crystal display electrode, wherein an air-permeable layer is formed and a transparent conductive layer is further laminated thereon. 2. The transparent conductive liquid crystal display electrode according to claim 1, wherein the metal nitride is a nitride of Al, Si, and / or AlSi. 3. The transparent conductive liquid crystal display electrode according to claim 1, wherein two or more layers of the metal nitride layer are laminated by a thin film forming method such as sputtering. 4. A transparent sheet having a solvent resistant layer / an air permeable layer made of an organic material formed on one surface, and a solvent resistant layer / an air permeable resistant layer and a transparent conductive layer made of a metal nitride on the other surface. The transparent conductive liquid crystal display electrode according to claim 1, wherein and are sequentially stacked.