JPH03215829A - Production of liquid crystal element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a liquid crystal element used for displaying images, etc., and specifically relates to a coating/baking type inorganic oxide insulating film formed on an electrode substrate. The present invention relates to a method for producing a liquid crystal element, characterized in that the liquid crystal element is obtained by simultaneously firing the liquid crystal element and an organic polymer alignment film formed thereon.

[Prior art] FIG. 1 shows a cross-sectional view of a general field-effect liquid crystal element.

In Figure 1, 1 is a transparent substrate, 2 is a transparent electrode film, 3 is metal wiring, and 4 is for improving the durability of liquid crystal alignment, suppressing electrochemical reactions on the electrodes, and preventing deterioration of visibility due to reflection of the electrodes. , an inorganic oxide insulating film, 5 an alignment film for controlling the alignment of liquid crystal, and 6 a liquid crystal.

Generally, a liquid crystal element as shown in FIG. 1 is manufactured through the following series of steps. That is, first, a transparent electrode film 2 and, if necessary, a metal wiring 3 are formed on a pair of transparent substrates 1, and then an insulating film 4 and an alignment film 5 are sequentially formed on at least one of the substrates 1. After the obtained alignment film 5 is subjected to an alignment treatment, the pair of substrates are placed facing each other, and liquid crystal 6 is filled between them to produce a liquid crystal element.

Methods for forming the inorganic oxide insulating film 4 in the above manufacturing method include a sputtering method and a method of applying and baking an insulating film material. Initially, the former method was widely used because it produced an insulating film with superior electrical insulation properties. However, this method requires heating the substrate to about 350° C. in a vacuum, resulting in poor productivity and requiring expensive equipment, which has been an obstacle to reducing device manufacturing costs.

However, in recent years, MOF-In manufactured by Tokyo Ohka Kogyo ■
With the development of excellent coating and firing type insulating film materials such as the K series and the NHC series manufactured by Nissan Chemical, and the development of printing equipment suitable for forming insulating films such as the Angstromer manufactured by Nissha Printing, sputtering It has now become possible to obtain an inorganic oxide insulating film with sufficient performance comparable to insulating films formed by the latter method, and under heating conditions of about 200 to 300°C. As a result, a method of forming an inorganic oxide insulating film on a substrate by applying an insulating film material onto an electrode substrate by a printing method or the like and baking it has become widely used, and the productivity of the insulating film forming process has improved. Significantly improved.

[Problems to be Solved by the Invention] However, when an insulating film is formed by coating and baking as described above, conventionally, an inorganic oxide insulating film is first formed on a substrate, and then the obtained insulating film is Since the alignment film was formed by applying the alignment film material onto the film and baking it again, it was necessary to perform the high temperature treatment (firing) process twice. Therefore, the manufacturing process becomes complicated, which is particularly inconvenient when going online, and manufacturing efficiency and manufacturing cost reductions are not sufficiently achieved.

SUMMARY OF THE INVENTION In view of the problems of the prior art described above, an object of the present invention is to simplify the steps of forming an insulating film and an alignment film in a method of manufacturing a liquid crystal element, thereby reducing manufacturing efficiency and manufacturing costs.

[Means and effects for solving the problem] As a result of intensive research, the present inventors have found that the above problem can be solved by simultaneously performing the firing process for obtaining the inorganic oxide insulating film and the firing process for obtaining the alignment film. We have found a solution to this problem and have arrived at the present invention.

That is, in the method for manufacturing a liquid crystal element of the present invention, when forming an inorganic oxide insulating film and an organic polymer alignment film on a substrate having an electrode for driving the liquid crystal by applying a voltage to the substrate, An insulating film material was first applied thereon, and then an alignment film material was applied on the unfired insulating film material, and then the insulating film material and the alignment film material were simultaneously heated and fired.

In the present invention, conventionally used insulating film materials and alignment film materials can be used, and their coating is performed by a printing method or the like. Further, the heating and baking conditions are appropriately set according to the insulating film material and alignment film material used so that an insulating film and alignment film with sufficient performance can be obtained.

Furthermore, in the manufacturing method of the present invention, the insulating film material is dried before being coated with the alignment film material, and the insulating film material is irradiated with ultraviolet light before baking.
A. In other words, if the surface is treated to improve wettability using a low-pressure mercury lamp, etc., it will be easier to apply the alignment film material, and at the same time, the ultraviolet energy of the low-pressure mercury lamp will create a high-performance insulating film. tends to be obtained. The amount of ultraviolet irradiation at this time is 50 mJ/cm2 or more,
Preferably 0. 5 to lOJ/cm'.

[Function] In the manufacturing method of the present invention, the firing treatment for obtaining the inorganic oxide insulating film and the firing treatment for obtaining the alignment film are performed simultaneously, so that the complicated high temperature treatment step is only performed once. The manufacturing process for liquid crystal elements is greatly simplified, and liquid crystal elements with the same performance as conventional ones can be produced more efficiently. Also,
According to the manufacturing method of the present invention, operating costs such as heating costs are significantly reduced, so the manufacturing cost of the element is reduced.

[Example 1 and Comparative Example 1 The following insulating film material was applied under the following printing conditions onto an electrode substrate on which a pattern for a liquid crystal element was formed using a transparent conductive film.

(Insulating film material) Ingredients: Mixed solution of organic titanium compound and organic silicon compound (metal concentration = 10% by weight, mixing ratio of organic titanium compound and organic silicon compound = t:i) Viscosity: 50 cp (25℃) Manufacturer: Tokyo Ohka Kogyo ■ Product name: MOF, Ti-St-ink (Printing conditions) Equipment used: Nissha Printing ■ Angstromer color plate Depth: 12 micron unevenness Ratio: concave: convex = 60 microns: 40 microns Amount of printing plate depression: 0.15 mm Next, in Example 1, the electrode substrate coated with the insulating film material was maintained at 150°C for 30 minutes. Dry the insulation film material,
Furthermore, ozone treatment (using a low-pressure mercury lamp, 1.OJ/c
m2 irradiation), while in Comparative Example 1, 300°C
The insulating film material was fired for 60 minutes.

Subsequently, the following alignment film materials were applied to these electrode substrates under the following printing conditions.

(Alignment film material) Ingredients: Polyimide (resin concentration: 3% by weight) Manufacturer: Toray ■ Product name: LP-64 (Printing conditions) Equipment used: Angstraw manufactured by Nissha Printing ■ Color plate depth: 5 microns Roughness ratio: concave: convex = 60 microns: 40 microns Printing plate indentation amount: 0.15 mm Next, the electrode substrate coated with the alignment film material was coated with the electrode substrate coated with the alignment film material. In Comparative Example 1, the insulating film material and alignment film material were fired at 300°C for 60 minutes, while in Comparative Example 1, the temperature was maintained at 300°C for 60 minutes.
The insulating film material was fired for 60 minutes to obtain electrode substrates each having an insulating film and an alignment film.

In both Example 1 and Comparative Example 1, the obtained film thicknesses were 1000±150 for the insulating film and 100±20 for the alignment film.

The dielectric breakdown voltage (BDV) of each of the electrode substrates on which the insulating film and alignment film were formed was measured using the apparatus shown in FIG. 2 under the following conditions. As a result, the film obtained in Example 1 had a
(standard deviation σ = 7), and the film obtained in Comparative Example 1 was 49v (
σ=8), and had almost the same performance.

In FIG. 2, numeral 7 indicates a blow bar made of tungsten carbide with a radius of 0.1 mm at the tip, 8 a push bull gauge, 9 a sample, 10 a variable voltage power source, and 11 an ammeter.

(BVD measurement conditions) Load: 10 g Next, each of the electrode substrates obtained above was subjected to alignment treatment, and then liquid crystal panels with a gap of 1.3 microns were each produced. And among them, spontaneous polarization (ps) is 9.6nC/
A liquid crystal element was prepared by sealing a cm2 of Sm*C liquid crystal, and the temperature characteristics of the drive margin were measured for each liquid crystal element using the drive waveform shown in FIG. 3 while fixing the frequency and varying the voltage.

In FIG. 3, C is a scanning voltage waveform, S1 is a signal voltage waveform for white (or black) writing, and S2 is a signal voltage waveform for black (or white) writing.

As a result, the liquid crystal element obtained in Example 1 had a sufficiently wide driving margin, similar to that obtained in Comparative Example 1.

Further, the liquid crystal alignment state in the liquid crystal element obtained in Example 1 was uniform throughout the entire surface, similar to that obtained in Comparative Example 1.

As described above, in the case of Example 1, manufacturing costs such as heating cost and equipment cost were low because only one firing process was required, and the obtained liquid crystal element had sufficient performance.

Example 2 and Example 2 The insulating film material was changed to the following, and in Example 2, the drying conditions for the insulating film material were 150°C for 30 minutes, and the baking conditions for the insulating film material and alignment film material were changed. The firing conditions were 200°C for 60 minutes, while in Comparative Example 2, the firing conditions for the insulating film material were 2.
00℃ for 60 minutes, and the alignment film material firing conditions were 200℃ for 60 minutes.
An electrode substrate having an insulating film and an alignment film was obtained in the same manner as in Example 1 for Example 2 and in Comparative Example 1 for Comparative Example 2 except that the time was 0 minutes.

(Insulating film material) Ingredients: Mixed solution viscosity of organic aluminum compound and organic silicon compound: 20 cp (25°C) Manufacturer: Nissan Chemical ■ Product name: NHC-A-20-1 41 1 In both Example 2 and Comparative Example 2, the obtained film thicknesses were 1100±150 for the insulating film and 100±20 for the alignment film.

When the dielectric breakdown voltage of each of the electrode substrates obtained above was measured in the same manner as in Example 1, the film obtained in Example 2 was 45 V (σ = 3), and the film obtained in Comparative Example 2 was 46 V.
v (σ=3), and had almost the same performance.

Next, liquid crystal elements were produced in the same manner as in Example 1 using each of the electrode substrates obtained above, and the temperature characteristics of the drive margin of each liquid crystal element were measured. The liquid crystal element obtained in Example 2 had a sufficiently wide driving margin, similar to that obtained in Comparative Example 2.

Furthermore, the liquid crystal alignment state in the liquid crystal element obtained in Example 2 was uniform throughout the entire surface, similar to that obtained in Comparative Example 2.

In the case of Example 2, as in Example 1, the manufacturing process was simplified, the cost was reduced, and a liquid crystal element with sufficient performance was obtained.

1 2 [Effects of the Invention] As explained above, according to the present invention, since the coating/baking type inorganic oxide insulating film is fired at the same time as the alignment film formed thereon, the liquid crystal The manufacturing process of the device is significantly simplified compared to the conventional method, and liquid crystal devices with sufficient performance can be produced more efficiently, and manufacturing costs are also significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a general field-effect liquid crystal element, FIG. 2 is a schematic diagram of a dielectric breakdown voltage measuring device used in an embodiment of the present invention, and FIG. FIG. 7 is a diagram showing drive waveforms when measuring temperature characteristics of a drive margin in one embodiment. 1: Transparent substrate, 1 3: Transparent electrode film, bimetallic wiring, : Insulating film, : Alignment film, : Liquid crystal, : Blowba, : Push bull gauge, : Sample, : Voltage variable power supply, : Ammeter, : Scanning voltage Waveform, : Signal voltage waveform for white (or black) writing, : Signal voltage waveform for black (or white) writing.

Claims (1)

[Claims] 1. When forming an inorganic oxide insulating film and an organic polymer alignment film on a substrate having electrodes for driving liquid crystal by applying a voltage, an insulating film material is first applied on the substrate. 1. A method for manufacturing a liquid crystal element, which comprises applying an alignment film material on the unfired insulating film material, and then heating and baking the insulating film material and the alignment film material at the same time. 2. Claim 1, characterized in that an alignment film material is applied after the unfired insulating film material is subjected to ultraviolet irradiation treatment.
The method for manufacturing a liquid crystal element described in .