JPH02129601A - Substrate for color filter - Google Patents

Abstract

PURPOSE:To obtain an over coating layer which can be formed by a method, such as spin coating or printing, suitable for mass production excellent in smoothing the surface ruggedness by laminating plural pieces of resin layers consisting of materials which are different in kinds, thereby forming the over coating layer. CONSTITUTION:After color filters 7 having regularity are formed on a light transmittable substrate 1, the over coating layer 8 consisting of at least two layers of the different resins 8a, 8b is formed thereon to constitute the above substrate. The lower layer 8a of the over coating layer 8 in the part in contact with the color filters 7 consists of the resin having good wettability with a binder, etc., constituting the color filters 7 and the layer 8b thereon is desired to have the good wettability with the resin forming the lower layer 8a. The resin of the uppermost layer 8b of the over coating layer 8 in contact with an ITO (Indium Tin Oxide) is preferably the resin with which the ITO film can be stably formed. The respective layers 8a, 8b of the over coating layer 8 which are respectively in the coatable form are selected. The stable formation of transparent electrodes is possible in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a color filter substrate used, for example, in a liquid crystal display element.

(Prior Art) A color filter substrate used in a liquid crystal display element is made by arranging red, green, and blue color filters regularly for each pixel on a glass substrate, and then depositing metal, etc. around each pixel. This creates a black matrix and emphasizes the contrast of each pixel.

This color filter is formed by means such as dyeing, printing, and electrodeposition, but generally has an uneven shape with a depth of 1 μm or more. An overcoat layer is usually formed on the color filter in order to smooth out the uneven shape and form a transparent conductive film, which is to become one electrode of the liquid crystal display element, thereon in a stable state. Here, acrylic resin is generally used as the material for the overcoat layer.

By the way, as liquid crystal display elements using color filters, polysilicon, amorphous silicon (a-3
i) etc. as a semiconductor layer (T
hin Film Transistor, TPT)
, or M I M (Metal-Insulato
An active matrix type using nonlinear elements such as r-Metal) elements is disclosed in, for example, JP-A-56-25.
It is disclosed and known in 714@ publication, Japanese Patent Application Laid-open No. 56-25777, and the like.

However, what has been put into practical use as a liquid crystal display element using a color filter is a small color liquid crystal display element of 10 inches or less. In addition, in a liquid crystal display device using TPT as a switching element, an overcoat layer and a transparent conductive film, which are sequentially formed on a color filter, cover the entire surface of the substrate, and the thickness of the transparent conductive film is as thin as several hundred angstroms. It is enough.

This type of liquid crystal display element is required to be larger in size and significantly lower in cost.

Color filter substrates for liquid crystal displays also use inexpensive O2 that requires less photolithography process, such as MIM elements.
There is a demand for the development of products for large liquid crystal display devices used as A (Office Automation) and large liquid crystal TVs using TPT elements.

In color filters for color liquid crystal displays using MIM elements, a transparent conductive film made of ITO (Indium Ti
It is necessary to form a stripe-shaped electrode corresponding to the pixel size of the color filter by forming a n 0 xide) film and using a photophosphorography method. On the other hand, even in large color liquid crystal display devices using TPT elements, in order to reduce electrode resistance as the size increases, the transparent conductive film on the overcoat layer is required to be thicker than before. There is.

(Problems to be Solved by the Invention) By the way, a large number of types of overcoat layers as described in (a) above are known so far. For example, the overcoat layer using acrylic resin is
As disclosed in Japanese Patent Application Laid-open No. 150806 and Japanese Patent Application Laid-Open No. 160902/1983, when an ITO film with a thickness of several thousand angstroms is formed on the film, fine wrinkles occur on the entire surface, which prevents the formation of a normal ITO electrode. has the disadvantage that it is impossible. In addition, overcoat layers using epoxy resin are disclosed in Japanese Patent Application Laid-open No. 60-2113307 and Japanese Patent Application Laid-open No. 81-6.
Although it is disclosed in Japanese Patent Application No. 624, etc., it is not compatible with the material constituting the color filter, and minute defects are generated on the surface. Furthermore, an overcoat layer using an inorganic substance is disclosed in Japanese Patent Application Laid-Open Nos. 57-78003 and 1988-
Although disclosed in Japanese Patent Application Laid-open No. 78107, Japanese Patent Application Laid-open No. 58-153903, and Japanese Patent Application Laid-open No. 58-224310, organic materials such as acrylic resins and epoxy resins are effective in smoothing the unevenness of color filters. Inferior to overcoat layers using In addition, when forming an overcoat layer using an inorganic material, CVD (Chemical
Cal Vapor Deposition) 'Creating low-cost color filters for LCD displays that require IA placement or high-temperature heat treatment, require extremely specialized color filter manufacturing methods, and lack productivity due to expensive equipment. Not in accordance with the intention. Furthermore, a method of layering an overcoat layer made of an inorganic material on an overcoat layer made of an organic material is disclosed in Japanese Patent Application Laid-open No. 60-112001 and Japanese Patent Application Laid-open No. 5
Although it is disclosed in Japanese Patent No. 9-17191 and the like, it goes without saying that the formation of an overcoat layer made of an inorganic substance is accompanied by the above-mentioned drawbacks.

In this way, conventional color filters for liquid crystal displays are particularly useful for large-sized liquid crystal TVs and, for example, OLEDs using MIM elements.
Suitable for A-type color LCD displays, it flattens unevenness on the surface of color filters to improve display quality, and is sufficient as an underlying overcoat layer necessary to stably and inexpensively manufacture electrodes made of transparent conductive films. There was nothing.

This invention is excellent in flattening unevenness on the surface of color filters, allows the formation of an ITO film with a thickness of several thousand angstroms without any hindrance, and is suitable for mass production such as spin cord or printing. An object of the present invention is to provide a color filter substrate having an overcoat layer that can be created using the following methods.

[Structure of the Invention] (Means for Solving the Problem) This invention forms a regular color filter on a light-transmissive substrate, and then forms an overcoat layer made of at least two or more different resins. It becomes. The lower layer of the overcoat layer in contact with the color filter is made of a resin that has good wettability with the binder that makes up the color filter, and the upper layer has good wettability with the resin that forms the lower layer. It is hoped that The resin in the uppermost layer of the overcoat layer in contact with the ITO film is preferably one that can form an ITO film stably, and each layer of the overcoat layer is selected to have a form that can be coated. Here, for example, the lower layer resin may be formed by using a spin cord to form an acrylic resin cellosolve acetate solution, and the uppermost layer may be formed by applying an epoxy resin or a resin made mostly of epoxy using a spin cord.

(Function) This invention applies a resin solution having good wettability to the components of the color filter onto a color filter formed by a printing method, a dyeing method, an electrodeposition method, etc., using a spin cord or a printing method. Coat to a thickness of 3 μm. The surface of the color filter is made of a hard pigment or a dye treated to make it insoluble with tannic acid, etc., and a binder.Of course, the coloring material is different for each color, but the binder may also be different for each color. An acrylic resin liquid having cellosolve acetate as a solvent exhibits good wettability for color filters having different surface conditions. The quality of this wettability is determined by forming a smooth film on a transparent substrate for each color.
A solution of the overcoat material is dropped and its contact angle is measured, or a certain amount of the solution of the overcoat material is dropped and the spreading speed is evaluated. If a material with poor wettability is used, the adhesion between the color fill and overcoat layer will be weak, and it may adhere to the other substrate on which the electrodes are formed, resulting in peeling or lifting during the process of encapsulating the liquid crystal. .

Here, a solution containing a 30% concentration acrylic resin as the above solvent is applied to a thickness of about 1.5 μm using a spinner. Next, it is heated at 90 to 120°C for several minutes to several tens of minutes to evaporate and solidify a portion of the solvent from the acrylic resin.

The lower layer of the overcoat layer that is in contact with the color filter portion must have good wettability with the material constituting the color filter. In addition, wettability with the material of the upper layer of the overcoat applied thereon and solvent resistance are also taken into consideration. Although acrylic resin has been described here as an example, other materials such as alkyd resin may also be used. Since the lower layer of the overcoat layer is applied directly to the highly uneven color filter portion, the larger the film thickness, the greater the probability of air being mixed in, and the smaller the film thickness, the better the finish.

Then, an epoxy resin having a solid content of 30 to 40% is further applied to the subsoil to a thickness of about 2 μm using a spinner. Here, epoxy resin was selected as a material capable of stably forming an ITO electrode. Acrylic resins are usually 3 at 160'C.
It is completely solidified by heating for 0 minutes or more, but since the wettability with the epoxy resin is poor when it is completely solidified, the heating conditions in (a) above were selected to provide conditions that are compatible with the epoxy resin liquid. Furthermore, after this, the epoxy resin was heated at 160 to 180'C.
Heat for 0 minutes or more to completely solidify and complete the overcoat layer.

The uppermost layer of the overcoat layer is preferably made of a material that satisfies the conditions that the ITO electrode can be easily formed and that it is compatible with the lower layer in the overcoat layer, and that it can be easily formed by means such as a spin corner or printing. Although epoxy resin has been described as an example here, examples of materials that satisfy such conditions include polyimide resins, polyamide resins, melamine resins, and silicone resins. Further, these resins may be selected from those modified by reacting various closely related compounds. Such an overcoat layer can be used even if the unevenness of the color filter is 2 μm.
It can be smoothed to a thickness of 0.5 μm or less, and on top of this, 0.5 μm or less can be smoothed.
A TTO electrode can be formed with good reproducibility by forming an ITO film with a thickness of 2 to 0.4 μm and using photolithography. Further, since the overcoat layer can be formed using a spin cord or a printing method, productivity is high.

(Example) The details of this invention will be explained below with reference to the drawings.

FIG. 1 is a diagram for explaining the manufacturing process for manufacturing one embodiment of the present invention. First, as shown in FIG. 1(a), a photosensitive dyed substrate 2 is applied onto a light-transmissive substrate 1 made of, for example, glass.

Here, the film thickness of the photosensitive dyed substrate 2 is 0.8 to 1.2 μm.
A certain degree is fine. Next, ultraviolet rays are irradiated onto the predetermined mask to cause a crosslinking reaction, as shown in FIG. 1(b).
A latent image 3 is formed on the photosensitive dyed substrate 2. Subsequently, development is performed to form a resin film 5 having openings 4 with a predetermined regularity, as shown in FIG. 1(C). After solidifying the resin WA5 by baking, Black 18
1 (manufactured by Nippon Kayaku) to form a light-shielding WA6 as shown in FIG. The film thickness increases to about 1.5 μm compared to No. 5.Then, a fixation treatment of light shielding No. 11!6 is performed in a solution containing tannic acid and tartarite.Next, using the printing method, the first Figure (e)
As shown in FIG. 2, red (R), green (G), and blue (B) color filters 7 are formed in portions corresponding to the openings 4, and the ink on the color filters 7 is fixed by baking.

The color filter 7 thus obtained has a thickness of approximately 2 μm.
It has a regular uneven shape with a depth of .

Next, as shown in FIG. 1(f), an acrylic resin containing methyl cellosolve acetate as a solvent is applied onto the color filter 7 using a spin coat 1- to a thickness of 1.0 to 2.5 cm.
The first resin layer 8a of the overcoat layer 8 is formed to have a thickness of μrn, preferably 1.5 μm.

Next, heat at 90 to 120°C for several minutes to several tens of minutes,
Part of the solvent is evaporated and solidified. Then, on the first resin layer 8a made of acrylic resin, an epoxy resin liquid containing methyl cellosolve acetate as a solvent is applied with a spin cord to a thickness of 1.5 to 3.0 μm, preferably 2
．． A second resin layer 8b of the overcoat layer 8 with a thickness of 0 μm is formed. Next, the second resin layer 8b is completely solidified by heating with iao'c for 100 minutes, thereby completing the overcoat layer 8.

In this embodiment, as the structure of the overcoat layer 8, the first resin layer 8a in contact with the color filter 7 is made of an acrylic resin that has good wettability with the ink of the color filter 7.
In addition, since the second resin layer 8b on this is made of epoxy resin that can stably form an ITO film, the overcoat layer 8b can be easily formed.
Once the ITO electrode is formed thereon, it is possible to prevent the occurrence of minute wrinkles and minute defects. Further, the surface of the overcoat layer 80 obtained in this example has gentle undulations, and the difference between high and low parts is 0.5μ.
It is within m. Even if the uneven shape of the color filter 7 is, for example, 4 μm deep, by slightly changing the conditions described above, the uneven shape after being coated with the overcoat layer 8 can be smoothed to within 0.5 μm. be. In addition, in terms of smoothing, since the first resin layer 8a has a large uneven shape,
The thinner the film, the better the results, and it is better to apply the second resin layer 8b thicker.

FIG. 2 is a schematic cross-sectional view showing an example of a liquid crystal display element using a color filter substrate 20 of this embodiment and using an MIM element as a switching element. An ITO film having a thickness of 0.2 to 0.45 m, preferably 0.25 μm, is formed on the overcoat layer 8 of the color filter substrate 20 by sputtering. Then, by photolithography, striped electrodes 21 are formed on the color filters 7 of each color, and matrix wiring 23 is newly formed on the light-transmitting substrate 22.
, an array base 25 on which pixel electrodes 24, switching elements (not shown), etc. are formed is prepared. and,
The color filter substrate 20 and the array substrate 25 are stacked so that the color filter 7 and the pixel electrode 24 and the light shielding film 6 and the matrix wiring 23 face each other, and a liquid crystal layer 26 is sandwiched in the gap. Furthermore, on the outer surfaces of the color filter substrate 20 and the array substrate 25,
By applying the polarizing plates 27 and 28, a desired liquid crystal display element can be obtained, and when displaying, it is preferable to provide illumination from, for example, the color filter substrate 20 side.

[Effects of the Invention] The present invention makes it possible to stably form transparent electrodes by sequentially forming layers made of at least two different resins on the overcoat layer of a color filter for a liquid crystal display using a spin code or printing method. , and has sufficient adhesive force with each pixel portion constituting the color filter, making it possible to provide a color filter substrate with high display quality at low cost.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining the manufacturing process for manufacturing one embodiment of this invention, and FIG. 2 is a cross-sectional view showing an example of a liquid crystal display element constructed from one embodiment of this invention. . 1... Light-transmissive substrate 7... Color filter 8... Overcoat layer 8a... First resin layer 8b... Second resin layer Agent Patent attorney Noriyuki Noriyuki Yudo Takehana Kikuo

Claims (1)

[Claims] A color filter substrate comprising a light transmitting substrate, a color filter formed on the light transmitting substrate, and an overcoat layer formed on the color filter, wherein the overcoat layer is made of different materials. A color filter substrate characterized by being formed by laminating a plurality of resin layers.