JPS62209414A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide a considerable cost reduction and to obtain a liquid crystal display element having high reliability and excellent mechanical strength by using a glass substrate which contains 0.3-7wt% alkaline component and is formed with a surface compressive stress layer on the surface as a glass substrate of the liquid crystal display element. CONSTITUTION:The glass substrate 1 contg. the alkaline component, i.e., com ponents of Na2O and K2O at a low ratio is immersed in a KNO3 melt to form the surface compressive stress layer 1a from the surface of the glass substrate 1 down to the prescribed depth. An electrode 3 is provided on such surface compressive stress layer 1a and further an oriented film 4 is provided on the electrode 3. Such glass substrates 1 are stuck to each other by a sealing material 5 and a liquid crystal 6 is injected into the spacing between the glass substrates 1 to manufacture the liquid crystal display element. The surface compressive stress layer 1a is obtd. by substituting the alkaline ions on the surface of the glass substrates 1 with the ions of the larger ion radius, for example, K ions. The alkaline component of the glass is preferably 0.3-7wt%, more preferably 4-4.5wt%.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid lf & display element using a glass substrate.
In particular, the present invention relates to a liquid crystal display element that does not require an insulating coating for preventing elution of alkaline components.

[Prior art]

In a conventional liquid crystal display element, as shown in FIG. 2, an insulating film 2 such as 5jOt is formed on two glass substrates 1, an electrode 3 is formed on this insulating film 2, and an electrode 3 is formed on this insulating film 2. In this configuration, an alignment film 4 is provided, glass substrates 1 are bonded together using a sealing material 5, and liquid crystal 6 is injected into the gap between the glass substrates 1. Generally, the glass substrate 1 is made of soda lime glass, which can be manufactured in large quantities at low cost. This soda lime crow contains 15wt of alkaline components Na, 0 + KtO.
% or more, and for this reason, an insulating coating 2 is formed on the glass substrate 1 to prevent the alkali components in the glass substrate 1 from eluting into the liquid crystal 7.

[Melting point that the invention seeks to solve]

But is it insulated on a glass substrate like this? Even if an LLI film is formed, the elution of alkaline components in the glass substrate cannot be completely prevented, and therefore, the decomposition of the liquid crystal due to the alkaline components,
There are problems in that the performance of the alignment film deteriorates, the creeping resistance near the electrodes decreases, and bleeding phenomena occur, shortening the life of the liquid crystal display element. Especially in large liquid crystal display elements, it is difficult to form an insulating film with a uniform thickness by binding.
), the above problems are likely to occur. Therefore,
The above problems can be solved by using a glass substrate that does not contain an alkali component, but a glass substrate that does not contain any alkali component has a high melting temperature, making it difficult to manufacture the glass substrate and at the same time causing a decrease in mechanical strength. There was a problem.

[Means for solving problems]

Alkaline component content is 0.3 wt% to 7 wt%
% and on which a surface compressive stress layer is formed is used as a glass substrate of a liquid crystal display element.

[Effect]

The alkali component content of the glass substrate is reduced, and the deterioration of the mechanical strength, especially the bending strength, of the glass substrate due to the reduction of the alkali component is improved by forming a surface compressive stress layer on the surface of the glass substrate. That is, when stress is applied to the glass substrate from the outside, the tension on the substrate surface is first used to cancel out the surface compressive stress, and the bending strength of the substrate increases accordingly.

[Example] In Fig. 1, l is an alkaline component, that is, Na, 0 and 2
This glass substrate 1 is a glass substrate with a small amount of 0 components.
A surface compressive stress layer 1a is formed at a predetermined depth from the surface of the glass substrate 1 by immersing it in an NOs melt. An electrode 3 is provided on this developed surface pressure silk stress layer la, an alignment film 4 is further provided on this electrode 3, a glass substrate 1 is bonded with a sealing material 5, and a liquid crystal 6 is injected into the gap between the glass substrates 1. Fabricate a liquid crystal display element. The surface compressive stress layer 1a is obtained by converting alkali ions on the surface of the glass substrate 1 into ions having a larger ionic radius, for example, [[*].

Next, specific examples will be described based on Table 1. Here, the bending strength and visibility are data for liquid crystal display elements manufactured using the glass substrates of samples A to G. Sample A has an alkali content of 4 wt%, plate thickness Q, and 7 tnm.
This was a glass substrate without a surface compressive stress layer, and its bending strength was 9 kg/-.

Sample B has the same alkali content as sample A, and the plate thickness is Q, 3.
tnm, which was immersed in IOH in KNOs fi solution at 450 °C to form a 20μ surface compressive stress layer, and the bending strength was 20 kg/ml. Sample C has the same alkali content as sample A, has a plate thickness of 1.1mm, and is heated at 450°G.
It was immersed in KNO3 melt for 4 hours to form a 10μ surface compressive stress layer, and the bending strength was 15 kg/m.
It was tl. The alkali content of the sample was 7 wt%.
, with a plate thickness of 0.7mm and a 10μ surface compressive stress layer formed under the same conditions as sample C, with a bending strength of 25.2 kg.
/md. In addition, sample F has an alkali content of 0.
3wt, plate thickness 1.11111, KN O3 at 450℃
It was immersed in the melt for 15 hours to form a surface compressive stress layer, and the bending strength was 15 icg/vdl.

The above samples A-F are all visible (degree of color unevenness)
However, only sample A, which does not have a surface compressive stress layer, had a bending strength of 9 #/ilJ! and was the smallest.

Generally, the bending strength of ordinary soda lime glass is 5 to 1
It is about 0 kg/-. However, the bending strength of all samples B-F with the surface compressive stress layer 1a was 15 g/
mt1 or more, and the bending strength is 1.5 to 2 times greater than that of general soda lime glass that does not have a surface compressive stress layer. In addition, sample G has an alkali content of 4 wt%, a plate thickness of 0.71, and is immersed in a KNO melt at 450°C for 48 hours to form a surface compressive stress layer of 30μ, and its bending strength is 25.6. kg/rnd,
The color unevenness is significant and it cannot be put to practical use.

That is, in order to form a surface compressive stress layer larger than 20μ, it is necessary to immerse the material in a high-temperature KNOs melt for a long time.
It was found that the surface of the glass substrate 1 was eroded, causing severe waviness on the substrate surface, and when two glass substrates were bonded together, the gap between the cells became noticeably uneven, causing color unevenness. did. Further, if the depth of the surface compressive stress layer is 1 μm or less, the bending strength is equivalent to that of ordinary soda lime glass, and there is no point in providing the surface compressive stress layer. Therefore, the depth of the surface compressive stress layer is preferably 1 μ to 20 μ, preferably 10 μ to 20 μ. In addition, if the content of alkaline components in the glass, that is, Na, O and KtO, is more than 7 wt%, an insulating coating is required to prevent the elution of the alkali components.
If it is less than 0.3 wt%, it will be difficult to form a desired surface compressive stress layer. Therefore, the alkaline component of the glass is preferably 0.3 wt% to 7 wt%, preferably 4 wt%.
Wt% to 4.5wt% is good. In these preferred embodiments, the alkali component of the glass substrate is 4wt% to 4.5w.
When the depth of the surface compressive stress layer is 10~20μ at t%, the bending strength is 15 kg/ml~20 kg/ml.
mft, and good results with no color unevenness can be obtained in terms of visibility.

〔effect〕

As described above, since the liquid crystal display element of the present invention uses a glass substrate with a low alkaline component, there is no practical problem even if an insulating coating for preventing alkaline component elution is not provided.
Moreover, by providing a surface compressive stress layer on the glass substrate, the decrease in the bending strength of the glass substrate due to the reduction of the alkali component can be improved, and the bending strength can be improved. Therefore, since the insulating film such as SiO2 is not necessarily attenuated, it is possible to achieve a significant cost reduction and to obtain a liquid crystal display element with high reliability and excellent mechanical strength.

Margin below Table 1゜

[Brief explanation of drawings]

FIG. 1 is a sectional view of a liquid crystal display element of the present invention, and FIG. 2 is a sectional view of a conventional liquid crystal display element. 1...Glass substrate 1a...Surface compressive stress/1 2...Insulating coating 3...Electrode 4...Alignment film 5...Sealing material 6...Liquid crystal representative Katama Katsube Thatch 1 figure and a half 2 figures

Claims (1)

[Claims] In a liquid crystal display element in which a liquid crystal is interposed between two glass substrates each having an electrode formed on the inner surface, the glass substrate contains an alkali component of 0.3 wt% to 7 wt%, and has a surface compressive stress on its surface. A liquid crystal display element characterized in that a layer is formed.