JPS5837620A - Production of substrate for liquid crystal cell - Google Patents

Abstract

PURPOSE:To obtain oriented films having high adhesive strength to substrates by immersing insulation substrates into a soln. of polyamic acid, heating the same while taking up to form the films of the polyamic acid and heat treating the films to form polyamide films after removing the unnecessary parts of the films. CONSTITUTION:An insulation substrates 1 is immersed in mixed solns. of polyamic acid and N-methylpyrrolidone and while the substrate is taken up gradually, the substrate is dried by IF heating 6 or the like, whereby films 7 of polyamic acid are formed on the substrate 1. The substrate 1 is beforehand formed with insulation films 13 of Al2O3 by forming transparent electrodes on a substrate 12 then coating an org. aluminum compd. on the electrodes 12 and heat treating the same. Said substrate formed with the films of the polyamic acid is removed of connecting terminal parts and sealing parts by using etching resist and is then heated to form polyimide films 13. The surfaces of the films 13 are oriented to form oriented films 14, then a pair of the substrates are sealed 3L to complete a liquid crystal cell. Thus the liquid crystal display element which is free from stripping or the like of the oriented films and has excellent heat resistance, etc. is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a liquid crystal cell substrate having a polyimide coating on the surface thereof as an alignment treatment film.

In order to improve the heat resistance characteristics of a liquid crystal display device, a polyimide film is sometimes used as an alignment treatment film for liquid crystals. A coating method using a spinner has generally been used to form a polyimide film on an insulating substrate, but this method has the disadvantage that the size of the substrate is limited and the thickness of the polyimide film becomes non-uniform. Furthermore, the adhesive force between the polyimide covering 111A and the sealing material is extremely low, and the resulting liquid crystal display device has a disadvantage in that its heat resistance properties are also deteriorated.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks, to provide a liquid crystal display device that can easily form a polyimide film with a uniform thickness, and has excellent heat resistance and mechanical strength. The present invention will be explained below based on the drawings.

1゛---3--- Figure 1 is a cross-sectional side view of a general liquid crystal display device.
1) is a liquid crystal cell substrate, which is made of an insulating substrate such as a glass plate having transparent electrodes such as InO on its surface. In a liquid crystal display device, a liquid crystal material (2) such as nematic liquid crystal is applied to a gap between two mutually facing liquid crystal cell substrates (1), at least one of which is transparent, and a sealing material (3) such as an epoxy resin. ) is enclosed in a structure. Figure 2G),
(B) is a diagram showing the structures of a conventional liquid crystal cell substrate and a conventional liquid crystal display device, respectively. A conventional method for manufacturing a liquid crystal display device will be explained based on FIGS. 2(a) and 2(b).

In manufacturing a conventional liquid crystal display device, first, as shown in FIG. 2(a), an insulating substrate 1. i
A transparent electrode (one transparent electrode made of a metal oxide such as In(J) is formed in a predetermined shape on η by a printing method, a vapor deposition method, etc.

An organic aluminum compound such as aluminum acetylacetonate is applied over the transparent electrode (13) by a dipping method, an evaporation method, a printing method, etc., and heat treatment is performed at 350° C. for 30 minutes to ensure close contact between the polyimide film and the glass substrate. In order to increase the degree of
37620 (2 No. is formed.Furthermore, a polyamic acid film is applied on the insulating film θ→ by a spinner, and heat treatment is performed at 350° C. for 30 minutes to form an orientation treatment film (141) of the polyimide film.The orientation treatment The film Q41 is rubbed in a certain direction to produce a liquid crystal cell substrate (1).A product is injected into the periphery of the two liquid crystal cell substrates produced in this way.
After applying and drying a sealant such as epoxy resin to a predetermined shape, two liquid crystal cell substrates are placed in dense ash, heated under pressure, and the sealant is cured to create a f(k crystal cell). Next, the liquid crystal material is injected and sealed from liquid crystal injection [1] to complete the liquid crystal display device as shown in FIG. 2 (b). In this method, an oriented film 0 layer is interposed between the sealing material (3) and the insulating film 03, and an oriented film U made of polyimide is formed.
111 deteriorated the adhesion between the sealing material (3) made of epoxy resin or the like and the insulation coating 0→. Unfortunately, liquid crystal display devices are weak in strength, and if a small amount of stress or impact is applied, the two insulating substrates will peel off, resulting in weak mechanical strength and poor moisture resistance and heat resistance. Ta. Moreover, the polyamic acid coating coated with spinner 1-5-- was dried with 111
Moreover, depending on how the insulating substrate is handled up to the heat treatment step and the heat treatment conditions, a polyimide film with a uniform thickness cannot be obtained.

The feature of the present invention that overcomes the conventional drawbacks is that a polyamic acid coating with a uniform thickness is formed on the insulating substrate by immersing the insulating substrate in a polyamic acid solution and pulling it up while heating the fCf & insulating substrate. Moreover, an unnecessary polyamic acid film is removed, the adhesiveness between the sealing material and the insulating substrate is improved, and a liquid crystal display device with mechanical strength is provided.

Next, a method for manufacturing the liquid crystal cell substrate of the present invention will be explained. A720. on an insulating substrate. In the past, the process of forming an insulating film was the same as in the past. Next, a polyamic acid solution is prepared without stirring. That is, polyamic acid, for example, PI manufactured by Hitachi Chemical Co., Ltd.
Add N-methylpyrrolidone 1005' to Q100F and mix well. Next, a mixed solution of acetone 7002 and N-methylpyrrolidone 1001 was added and mixed little by little while stirring to make a solution in which PIQ was diluted 10 times with 11i'8.
After 2-3 lids, use 1 tbsp. An insulating substrate such as glass is immersed in a mixed bath solution of the prepared polyamic acid, acetone, etc., and IN-methylpyrrolidone, and while being slowly pulled up, an infrared heater, etc. is applied from both sides of the insulating substrate. The plate is heated to a surface temperature of 120°C to 150°C. Figure 3 shows this situation.
The insulating substrate (1) is immersed in the mixed solution 7+M (5) filled in the container (4), and slowly pulled up in the direction of the arrow while passing through the infrared heater (6), and placed on the insulating substrate (]). A ruptured membrane (7) of polyamic 11p is formed. In addition, (8) is an insulating substrate holder, and this holder is made of a sponge-like elastic material (9) to relieve stress applied to the insulating substrate (1) by the heat of the infrared heater (6).
) must be provided between the insulating substrate (1) and the insulating substrate (1). The polyamic acid coating (7) produced in the diagonal manner becomes a fairly hard coating with a uniform thickness, and the polyimide coating obtained by heat treatment in the post-process also becomes uniform.

Next, etching resist, for example, protocol
-7- Co., Ltd. 534O-C was coated on the polyamic acid coating (temporary) 2 by a screen printing method, excluding the external connection terminal portion and the seal portion, and then dried.

Next, after removing the polyamic acid solution from the external connection terminals and the sealing area by etching with a 3-ton sodium hydroxide solution, the insulating substrate was washed with water and then ultrasonically cleaned in trichloroethane. , remove the etching resist.

The insulating substrate from which the etching resist has been removed is heat-treated at 350 DEG C. for 30 minutes (3)11 to cause a crosslinking reaction in the polyamic acid to form a polyimide film. The polyimide coating is rubbed in a certain direction with absorbent cotton to perform an alignment treatment, thereby forming an alignment treatment film and completing a liquid crystal cell substrate.

A sealing material such as EBOKI 7-Tan-1 resin is applied by screen printing onto the sealed portion of the completed liquid crystal cell substrate on which the polyimide film is not formed, and the other liquid crystal cell substrate is fixed to the surface. They are placed facing each other with an interval of 1 lAj and heated under pressure to harden the sealing material to produce a liquid crystal cell. There is a liquid crystal substance inside the liquid crystal cell! i (Example: Japanese Patent Publication No. 53-3762
For example, a P-type nematic liquid crystal (3046 manufactured by Chisso Corporation) was sealed to produce a liquid crystal display device.

FIG. 4 is a cross-sectional side view of the liquid crystal display device that has been qrted, showing sealing material (3), A, 720. An insulating film consisting of (1:3
Therefore, the adhesive strength IW between the insulating substrate a and the sealing material (3) is good, and the two insulating substrates do not peel off. The device was moisture resistant and heat resistant by 1 V. Note that (2) is a liquid crystal material '1 no ↓, (1 polish), a transparent electrode, (
[Φ is an alignment film made of a polyimide film.

100°C for the i1M product display device n of the present invention manufactured.
, 700 hours heat resistance test and 120℃, 2at
The liquid crystal orientation (1/1) was as good as IJI (the first time it was produced), and no alignment disorder or discrimination occurred.

As explained above, the present invention has mechanical strength and durability. ! +ii 4'l 2. There is a great advantage that a liquid crystal display device with excellent heat resistance can be provided.

4. Drawing o simple 'f, 1j8A 'J] Figure 1 is
Figures 2 (a) and 2 (b), such as Figure 11, are conventional examples, and (a) shows 1.
(B) R is a cross-sectional side view of a liquid crystal display device. FIG. 4 is a diagram for explaining the manufacturing method of the liquid crystal cell substrate, and FIG. 4 is a cross-sectional side view of the liquid crystal display device.

(1) Liquid crystal cell board (2) Liquid crystal material (3) Seal material 01) Insulating substrate 0shi Transparent electrode q3 Insulating coating (141 alignment treatment film Figure 1 　　　　2 Figure 2 (stomach) (mouth +1 12 13 14 （／／／ It 13 IA 12 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) A step of immersing an insulating substrate in a mixed solution of polyamic acid, acetone, and N-methylpyrrolidone, and lifting the insulating substrate from the mixed solution while heating it to form a polyamic acid coating on the insulating substrate. 1. A method for manufacturing a liquid crystal cell substrate, comprising the steps of forming a polyimide film on the insulating substrate by heat-treating the insulating substrate. (2) A step of immersing the insulating substrate in a mixed solution of polyamic acid, acetone, and N-methylpyrrolidone, and lifting the insulating substrate from the mixed solution while heating it to coat the entire surface of the insulating substrate with polyamic acid. a step of removing unnecessary portions of the polyamic acid coating formed on the insulating substrate, and further heat-treating the insulating substrate to form a polyimide coating p in a predetermined shape on the insulating substrate.
2. A method for manufacturing a liquid crystal cell substrate, comprising the steps of: 2.