JPS61285428A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To prevent the deterioration of an insulating film contg. SiO2, network forming oxide except SiO2, intermediate oxide of an element having a low atomic weight and intermediate oxide of an element having a high atomic weight by a heat treatment by providing an electrode substrate having the above-mentioned insulating film between a glass substrate and electrode film. CONSTITUTION:The insulating film 2 contg. the SiO2, the network forming oxide except the SiO2, the intermediate oxide of the element having the low atomic weight and the intermediate oxide of the element having the high atomic weight is provided between the glass substrate 1 and the electrode film 3 to constitute the electrode substrate. The insulating film 2 contg. the plural oxides of the elements having the different atomic weights in the above-mentioned manner is used in the liquid crystal display element, by which the structure thereof is made more random and complex. The elution of the alkali ions of Na, etc. from the glass substrate 1 to the liquid crystal is thus effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element, and particularly to an insulating coating formed between a glass substrate and an electrode film of an electrode substrate.

[Conventional technology]

Generally, liquid crystal display elements (LCD)
As shown in FIG. 1, the electrode substrate of the LD 1spray (hereinafter abbreviated as LCD) consists of a glass substrate 1, an insulating coating 2 uniformly deposited on the upper surface of the glass substrate 1, and an insulating coating coated with the insulating coating. 2, and an alignment film 4 that covers the electrode film 3 and the insulating film 2 so that the top surface is flat.

The insulating liquid 11!2 in conventional LCDs is mainly formed of silicon dioxide (Sin,) or titanium dioxide (Ti0,) using a vacuum deposition method or a chemical spray method.

[Conventional problems]

However, although the conventionally used vacuum evaporation method can form an insulating film with excellent characteristics, it has problems in terms of mass production.

Further, the chemical spray method has problems in that the properties of the insulating film formed are poor and materials are likely to be wasted.

On the other hand, it is also possible to use a printing method, but this poses a problem in terms of mass production.

Compared to the various methods described above, the immersion method is characterized in that it can process a large number of electrode substrates simultaneously, does not waste materials, and is suitable for mass production.

However, in the conventional immersion method, when an insulating film is made using only Sing, its refractive index is
3n) Since the refractive index is lower than that of the electrode film made of oxide, there is a problem in that when viewed as an LCD, the electrode pattern stands out when not driven.

In addition, in order to increase the refractive index of the insulating film, Ti0t was added to 2
Layering has also been done, but this has the problem of increasing the number of steps and increasing costs.

Further, if only a single layer of TiO□ is provided, alkali ions such as sodium ions (Na'') are eluted from the glass substrate to the liquid crystal, which causes a problem in that display patterns smear in reliability tests.

Furthermore, in conventional LCDs, the insulation coating deteriorates due to heat treatment in the process after LCD assembly, such as printing and baking Ag paste to connect the pin connector to the terminals, reducing the reliability of the LCD. There was a problem with letting it work.

In order to solve the above-mentioned conventional problems, the present invention prevents alkaline ions from leaching into the liquid crystal, makes the refractive index of the insulating film close to that of the electrode film, makes the electrode pattern less visible, and also makes it difficult to see the electrode pattern in the subsequent process. An object of the present invention is to provide an LCD that prevents deterioration of an insulating film due to heat treatment, thereby improving reliability and display quality.

[Means for solving problems]

The LCD according to the present invention has an insulating coating formed of a film containing silicon dioxide, a network-forming oxide other than silicon dioxide, an intermediate oxide of an element with a small atomic weight, and an intermediate oxide of an element with a large atomic weight, on a glass substrate. and an electrode film.

[Effect]

In the LCD according to the present invention, the insulating coating includes silicon dioxide, a network-forming oxide other than silicon dioxide, an intermediate oxide of an element with a small atomic weight, and an intermediate oxide of an element with a large atomic weight. By including a plurality of oxides, the structure becomes more random and more complex, thereby effectively preventing the elution of alkali ions such as Na'' from the glass substrate to the liquid crystal.

In addition, by bringing the refractive index of the insulating film closer to that of the electrode film, the electrode pattern becomes less visible when not driven, and the LC
Increase visibility of D.

Furthermore, deterioration of the insulating film due to heat treatment after LCD formation is prevented, and the reliability of the LCD is improved.

〔Example〕

Next, before going into the description of Examples, the classification of glass constituent elements will be explained.

Generally, oxides of glass constituent elements are classified as (11
Network-forming oxides with relatively strong covalent bonding properties, (2) Network-modifying oxides with relatively strong ionic bonding properties and unable to form a solid by themselves, (3) Intermediate between network-forming oxides and network-modifying oxides. Intermediate oxides exhibiting the properties of

However, when looking at the formation of an insulating film by the dipping method, the inventors discovered that intermediate oxides can be further subdivided into two types in terms of their ability to suppress (block) the diffusion of alkali ions such as Na3. In other words, intermediate oxides include oxides with relatively small refractive indexes of elements such as A1 and Ti, which have small atomic weights, and oxides with relatively small refractive indexes, such as Zr, Ta, and Zr, which have large atomic weights.
It is divided into oxides of elements such as In and Pb whose refractive index is relatively high. If these are classified according to the synchronous table, the glass constituent element classification table shown in FIG. 3 will be obtained.

Next, one embodiment of the present invention will be described.

In the LCD of one embodiment of the present invention, S I Ot
An insulating film made of -ZrOt-A1z03-TatOs 52o3 is formed by a dipping method. Specifically, organic solvent-soluble organometallic compounds of silicon (Si), organometallic compounds of zirconium (Zr), aluminum (
The organometallic compound of AI), the organometallic compound of tantalum (Ta), and the organometallic compound of boron (B) are dissolved in a growth solvent and reacted with each other, and preferably a chelating agent is added to stabilize the solution. is added to obtain a solution uniformly containing the generated reaction product, and after immersing a glass substrate in this solution, it is fired to remove the organic solvent, and
z ZrOz A l t O3T a z Os
An insulating film made of a B t Ox film is formed on a glass substrate.

It is preferable that the proportions of the organometallic compounds of Si, Zr, Ta, B, and At in the above solution be within the following range in terms of weight ratio of oxides.

Stow = 10-30 (weight%), Zr0t”
10-20 (wt%), TatOs=20
~70 (wt%), BzCh = 2~10
(% by weight), Al t Os = 1-5 (% by weight).

However, it is not limited to the above range as long as the purpose of the present invention is achieved.

As the organometallic compound of Si, organic silane compounds such as ethyl silicate (tetramer of ethyl silicate) tetramethoxysilane, tetraethoxysilane, and vinyltris(2-methoxyethoxy)silane are preferable.

In addition, as the organometallic compound of Zr, tetraethoxyzirconium, tetraisoproxyzirconium (
Zr(OC5Hy)4), zirconium tetraacetylacetonate (Zr(acac)*), etc. are preferable.

Further, as the organometallic compound of A1 above, triethoxyaluminum, triisoproxyaluminum, tri-n-butoxyaluminum (AI(OC4Hg)s
), trisacetylacetonatoaluminum, etc. are preferable.

Further, as the organometallic compound of Ta, pentaethoxytantalum, pentaisoproxytantalum, pentabutoxytantalum (Ta(OC4HJS), pentaacetylacetonatotantalum, etc.) are preferable.

Furthermore, as the above-mentioned compound B, tryptoxyboron (B (OC4Hq)s), boric acid, triethoxyboron, etc. are preferable.

Organic solvents for dissolving these organometallic compounds include:
Methyl ethyl ketone (MEK), ethyl acetate, ethanol, methanol, etc. are preferable.

Further, as the chelating agent added to stabilize the solution, acetylacetone, triethanolamine, etc. are preferable.

When a solution prepared by mixing these is used as an immersion liquid, and a glass substrate is immersed in it and then fired at a temperature of 400°C or higher, particularly around 500°C, 5iO1-ZrO2
An insulating film made of A1z03 Taxes Btus is formed. SL Zr contained in the immersion liquid,
, A1% By controlling the amounts of Ta and B, the viscosity of the immersion liquid, the rate of pulling the glass substrate out of the immersion liquid, etc., an insulating film having a thickness of 5000 Å or less can be freely formed.

The insulating film thus formed is not only transparent but also has high film strength and high insulation properties. Therefore, the elution of alkali ions such as Na'' from the glass substrate is completely prevented, making it possible to mass-produce highly reliable LCDs.

First, while stirring a three-necked flask equipped with a stirrer and a reflux condenser and introducing nitrogen gas (N2), (1) ethanol + acetylacetone, (21AI
(OC4Hda)3 is sequentially added to the flask. Next, boil these while refluxing, and then (3) add ethyl silicate. Subsequently, (41Zr(OC1Ht)< , (51Z r (acac) #, (61Ta(OC4H9)S, (71B (OC4HJs)) dissolved in (8) CzHsOH solution are further added to the reaction solution.

The concentrations of the solution created in this way are as follows: Stow -24,6 (wt%), Zr0t =16.1 (wt%), Tag's -
54,6 (wt%), Btus -3,56 (wt%), Altos = 1.1 (wt%).

Using this solution as an immersion liquid, the glass substrate was immersed in the same wave, and then the glass substrate was pulled up at a pulling rate of 60 clI per minute.
Bake for a minute. As a result, the film thickness on the glass substrate was approximately 10
00 people's insulation coating was formed.

On the glass substrate 1 on which the insulating film 2 has been formed, an electrode film 3 is further formed by sputtering, and after buttering,
By coating a polyimide film and forming an alignment film 4 by rubbing, the electrode substrate for LCD shown in FIG. 1 can be obtained.

Thereafter, as shown in FIG. 2, two electrode substrates with their alignment films 4 facing each other are pasted together with a sealant with a spacer 5 in between so that the gap is 10 μm, and in this gap, for example, a nematic liquid crystal 6 is sealed and a polarizing plate 7 is attached to each electrode substrate, a twisted nematic type LCD is completed.

The LCD manufactured in this way is made of SiOg-Z r
OtA1! Os −T at Os
Since the insulating film was formed with a B t Os film, Zr, T
The refractive index of the insulating film is 1.60 to 2 depending on the content of a.
．． The refractive index can be adjusted within the range of OO, and therefore the refractive index of the electrode film 3 can be approximated to 1.8 to 1.9, the electrode pattern is difficult to see when not driven, and visibility as an LCD is good.

In addition, even if high-temperature treatment such as printing and baking a conductive coating agent on the terminal area after forming the LCD, the display pattern during driving, which is the standard for determining whether or not alkali ions have eluted, may be distorted, so-called smearing. The phenomenon is unlikely to occur. For example, under an accelerated humidity test at 80° C. and 90%, the time for the bleeding phenomenon to occur is approximately 30% longer than in the case of a single layer of SiO. Therefore, under normal temperature and normal pressure, the LCD has a longer life.

〔Effect of the invention〕

As explained above, according to the present invention, the film is formed of a film containing silicon dioxide, a network-forming oxide other than silicon dioxide, an intermediate oxide of an element with a small atomic weight, and an intermediate oxide of an element with a large atomic weight. The insulating film prevents the elution of alkali ions such as Na'' from the glass substrate to the liquid crystal, and brings the refractive index of the insulating film closer to that of the electrode film, making the electrode pattern visible and improving the visibility of the LCD. , LCD
The effect of preventing deterioration of the insulating film due to heat treatment after formation can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the configuration of an electrode substrate in a liquid crystal display element, Figure 2 is a cross-sectional view of a liquid crystal display element constructed using the electrode substrate shown in Figure 1, and Figure 3 is a glass This is a constituent element classification table. In the figure, 1...Glass substrate, 2...Insulating film, 3...Electrode film, 4...Alignment film, 5...Spacer, 6... ...Liquid crystal, 7...Polarizing plate. Figure 1 1. Glass board 2:? Coverage A turn 3: Denmo Kazuhide
4: Alignment film 5: Also X-sa 6: Liquid crystal 7: Fu Yulin

Claims (1)

[Claims] The insulating film interposed between the glass substrate and the electrode film contains silicon dioxide, a network-forming oxide other than silicon dioxide, an intermediate oxide of an element with a small atomic weight, and an intermediate oxide of an element with a large atomic weight. A liquid crystal display element characterized by comprising an electrode substrate formed of a film.