JP2870076B2 - Method for manufacturing color liquid crystal display element - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color liquid crystal display element used for a color liquid crystal television or the like, and more particularly, to formation of a protective film for covering a color filter. Method improvement.

[Conventional technology]

In general, as shown in FIG. 3, a color liquid crystal display element has a pair of transparent substrates 1 and 2 opposed to each other at a predetermined interval with a sealing material 3 interposed therebetween.
The liquid crystal 4 is sealed in the sealed space formed by the above.

The inner surface of one of the transparent substrates 1 is provided in one direction (third direction).
In the figure, red elongated in the parallel lateral direction) to the paper surface, green, blue three color filters _{5 (5 R, 5 G,} 5 B)
However, they are alternately and repeatedly arranged in a direction perpendicular to the direction (in FIG. 3, a direction perpendicular to the paper surface) as shown in FIG. In addition, each color filter 5 _R , 5 _G , 5
_B has different thicknesses because the layer thickness of the liquid crystal 4 is set so as to obtain an optimal transmission and blocking state for each light passing therethrough.

The entire surface of the color filter 5 is covered with a protective film 6 made of a resin such as polyimide, and a plurality of transparent electrodes 7 made of an ITO film or the like extending in the same direction as the color filter 5 are provided thereon. Are arranged at regular intervals in the direction perpendicular to the direction. Further, the upper surface is covered with an alignment film 8, which is in direct contact with the liquid crystal 4.

On the inner surface of the other transparent substrate 2, a plurality of transparent electrodes 9 made of an ITO film or the like extending in a direction orthogonal to the transparent electrode 7 are arranged at regular intervals. A region facing the electrode 7 forms a pixel region. The transparent electrode 9 is covered with an alignment film 10,
This alignment film 10 is in direct contact with the liquid crystal 4.

When manufacturing a color liquid crystal display device having the above configuration,
Protective film 6, as shown in FIG. 4, after forming the color filter _{5 (5 R, 5 G,} 5 B) on one of the transparent substrate 1,
It is formed by a process of covering it with a resin. In this step, to form the protective film 6, first, a material to be the protective film 6 is applied to the entire surface of the color filter 5 by a normal printing method. In the printing method, for example, as shown in FIG. 6, the liquid protective film material 12 dropped from the nozzle 11 is transported while being thinly and uniformly stretched by a plurality of rollers 13,
This is applied to the printing relief plate 15 provided on the peripheral surface of the last roller 14.
To the surface of the moving stage 16
This is performed by printing on the color filter 5 of the transparent substrate 1 placed thereon. Thus, the color filter 5
After the material for the protective film is applied thereon, the material is preliminarily dried and cured, whereby the solid protective film 6 can be finally obtained.

[Problems to be solved by the invention]

In the above-described conventional method for manufacturing a color liquid crystal display element,
After applying the material for the protective film on the color filter 5 of the transparent substrate 1 by a printing method, when pre-drying the material,
As shown in FIG. 5, the protective film 6 ′ before being hardened flows out little by little toward the lower side, and the film thickness at the edge portion (the portion within the dashed circle) of the color filter 5 is reduced. There is a problem that the coverage of the color filter 5 is deteriorated.

Therefore, in order to improve the covering property, it is conceivable to use a high-viscosity material. However, if such a material is used, the covering property is increased, but on the other hand, the flatness of the protective film surface is deteriorated. There is a problem.

Furthermore, since the respective coefficients of thermal expansion of the transparent substrate 1, the color filter 5, and the protective film 6 are different, even after the protective film 6 is cured, the heat treatment in the subsequent process may cause the difference in the above-described coefficient of thermal expansion. A stress is generated, and the stress concentrates on a thin portion of the protective film 6 (a portion within a broken circle in FIG. 5). For this reason, there is also a problem that a crack is generated in that portion and the transparent electrode 7 (see FIG. 3) formed on the protective film 6 is disconnected.

The present invention has been made in view of the above-described conventional problems, and its object is to improve coverage at an edge portion of a color filter without deteriorating flatness of a protective film,
It is an object of the present invention to provide a method for manufacturing a color liquid crystal display device that can prevent the occurrence of cracks at the edges.

[Means for solving the problem]

The method for producing a color liquid crystal display element of the present invention comprises, on a color filter formed on the inner surface of one of the pair of transparent substrates constituting the color liquid crystal display element, substantially the same organic compound. The method is characterized by comprising a step of forming a protective film composed of a plurality of layers by performing application and preliminary drying of the protective film material a plurality of times and curing.

[Action]

If a thick protective film is to be formed at once, the degree of flow of the protective film before curing to the lower one becomes extremely large as shown in FIG. Only a thin protective film can be obtained.

Therefore, if the coating and drying of the material for the protective film are performed a plurality of times as in the present invention, a plurality of thin protective films can be laminated, so that a thicker protective film as a whole can be obtained. . In addition, since it is not necessary to use a material having a high viscosity, the flatness of the surface of the protective film is maintained, and the thickness of the protective film is further increased. Can also be prevented.

In addition, when a material to which a silicon compound is added is used as the material for the protective film, the hardness of the protective film can be increased, so that the cracks can be more effectively prevented.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1A to 1E are cross-sectional views showing a process of forming a protective film, which is a main part of a manufacturing process according to one embodiment of the present invention.

In this embodiment, first, as shown in FIG. 1 (a), on a transparent substrate 1 made of glass or the like, similarly to the conventional red, green, color filter 5 consisting of blue three colors (5 _R, 5 _G ,
5 _B ). These three color filters 5 _R ,
5 thickness of _G, 5 _B is red in the figure, the green is shown to be thicker in the blue order, all three colors may be the same thickness, or blue, green, to be thicker red order May be formed.

Next, as shown in FIG.
A first protective film 21 'is applied by a printing method as shown in FIG. 6 on the transparent substrate 1 on which is formed. As a material for the protective film at this time, for example, A polyimide-based material containing about 20 mol% of a silicon compound as shown by is used. The content of the silicon compound is desirably in the range of, for example, 5 to 50 mol%.

Thereafter, the first protective film 21 'is preliminarily dried and cured to obtain a solid first protective film 21 as shown in FIG. 1 (c). The thickness of the protective film 21 is
The thickness is reduced by about 20 to 30% as compared with the thickness of the protective film 21 'before curing.

Subsequently, a second protective film is formed on the first protective film 21 by repeatedly applying the same method as the method of forming the first protective film 21. That is, as shown in FIG. 1 (d), a second-layer protective film 22 'is first applied on the first-layer protective film 21 obtained by curing by the same printing method as described above. . At this time, the same material as that used when applying the first-layer protective film 21 'is used. Thus, the second protective film 22 'is formed.
Is applied and then pre-dried and cured to form a solid second-layer protective film as shown in FIG. 1 (e).
Get 22. The film thickness of the protective film 22 is reduced by about 20 to 30% as compared with the film thickness of the protective film 22 'before curing as described above.

As described above, by applying and drying the material for the protective film on the color filter 5 twice, a two-layer groove of the first protective film 21 and the second protective film 22 is formed. Thus, a thick protective film 20 having a film thickness almost twice that of the related art is formed.

According to the present embodiment, as described above, the application and drying of the material for the protective film are performed twice, so that the first layer of the edge portion of the color filter 5 is formed as in the case of FIG. Even if the film thickness of the protective film 21 is reduced, a sufficient film thickness can be obtained by further forming the second layer of the protective film 22 thereon, thereby obtaining very excellent coverage. be able to. In addition, since it is not necessary to use a material having a high viscosity as a material for the protective film, the flatness of the surface of the protective film 20 can be maintained high.

Further, as described above, the thickness of the protective film 20 at the edge portion of the color filter 5 can be made sufficiently large, and further, by using a material containing a silicon compound as the material for the protective film, the protective film 20 can be formed. Since the hardness of the protective film 20 can be increased, the protective film 20 can sufficiently withstand the stress generated at the time of the heat treatment in the subsequent step, and can prevent the occurrence of cracks as in the conventional case. Therefore, disconnection of the transparent electrode due to cracks as in the related art can be reliably prevented. Further, since a polyimide-based material is used as the material for the protective film, the thermal expansion coefficient of the protective film can be made close to that of ITO, which is a material of the transparent electrode, and thus the above-mentioned stress itself can be suppressed to a small value.

Next, FIG. 2 is a sectional view showing the structure of a protective film obtained according to another embodiment of the present invention.

In this embodiment, the steps of applying and drying the material for the protective film are performed twice, and in this embodiment, the steps of applying and drying the material for the protective film are performed n times in the same manner as in the above example. (N ≧ 3). In this embodiment, finally, an n-layer structure protective film 30 including a first protective film 31, a second protective film 32,..., An nth protective film 3n is obtained. Can be

Therefore, according to the present embodiment, since the thickness of the protective film 30 can be further increased, a protective film having even more excellent flatness and coverage can be obtained, and cracks occur in the protective film. Can be more reliably prevented. Moreover, an arbitrary film thickness can be obtained by appropriately setting the number of times of application and drying.

In each of the above embodiments, a material containing a silicon compound was used as a material for the protective film. However, if it is not necessary to increase the hardness of the protective film, it is not necessary to intentionally include the silicon compound.

Further, the present invention can be applied not only to the color liquid crystal display device having the structure shown in FIG. 3, but also to any device having a structure in which a protective film is formed on a color filter.

〔The invention's effect〕

According to the present invention, a thicker protective film as a whole can be obtained by performing the coating and drying of the protective film material a plurality of times, so that the coverage at the edge portion of the color filter is greatly improved, Cracks can also be prevented. Moreover, since there is no need to use a material having a high viscosity, the flatness of the surface of the protective film can be maintained high.

In addition, when a material to which a silicon compound is added is used as the material for the protective film, the hardness of the protective film can be increased, and thus the occurrence of cracks can be more effectively prevented.

[Brief description of the drawings]

1 (a) to 1 (e) are cross-sectional views showing a process of forming a protective film which is a main part of a manufacturing process according to one embodiment of the present invention, and FIG. 2 is obtained by another embodiment of the present invention. FIG. 3 is a cross-sectional view showing a structure of a general color liquid crystal display element, FIG. 4 is a cross-sectional view showing a conventional method of forming a protective film, and FIG. FIG. 6 is a cross-sectional view showing a problem of a method of forming a film. FIG. DESCRIPTION OF SYMBOLS 1 ... Transparent substrate, 5 ... Color filter, 20 ... Protective film of two-layer structure, 21 ... Protective film of the first layer, 22 ... Protective film of the second layer, 30 ... N-layer structure , A first-layer protective film, 32, a second-layer protective film, 33, a third-layer protective film, 34, a fourth-layer protective film, 3n ... ... n-th protective film.

Claims (2)

(57) [Claims] 1. A method of applying a material for a protective film made of substantially the same organic compound to a color filter formed on an inner surface of one of a pair of transparent substrates constituting a color liquid crystal display element. A method for manufacturing a color liquid crystal display element, comprising a step of forming a protective film composed of a plurality of layers by performing predrying a plurality of times and curing. 2. The method for manufacturing a color liquid crystal display device according to claim 1, wherein said protective film contains a silicon compound.