JPS62119501A - Color filter - Google Patents

Abstract

PURPOSE:To improve the color contrast among individual colors by providing a smooth overcoat by layer on a printed color film of a color filter formed on a transparent substrate by the printing system. CONSTITUTION:A liquid transparent resin is overcoated on the color filter due to printing and is hardened, and thereby, <=1mum minute ruggedness on the surface of a color ink pattern 6 on a transparent base body 1 is leveled by the transparent resin to make the surface of the color ink pattern smooth, and irregular reflection of an incident light is prevented. With respect to the resin which forms an overcoat layer 3 on a color ink film 2, a thin film consisting of a thermoplastic acrylic resin may be used instead of the liquid resin, and this thin film is laminated by heating and pressuring to level the ruggedness of the color ink film 2. Thus, the contrast among individual colors is improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention utilizes a printing method to form a colored film for a color filter using transparent colored ink on a transparent gas, and coats the surface of the colored film with a transparent resin. This relates to a color filter produced by a printing method with an overcoat.

(Technical Background and Problems Therein) In general, color filters used in liquid crystal displays are produced using a photolithography method in which a gelatin layer is patterned and dyed using photolithography.

However, recently, printing method color filters in which a color pattern is directly formed on a transparent substrate using printing technology have been put into practical use.

This printing method color filter has a shorter manufacturing process than photolithography color filters, making it suitable for mass production, and since it uses pigments, it has superior heat resistance and weather resistance compared to other colorants. ing.

However, since this is a printing method that uses printing ink, when the ink is transferred from the ink transfer body to the printing medium, the ink is split between the transfer body and the printing medium, resulting in minute irregularities on the printed ink surface. . Therefore, the light transmitted through the filter is scattered or reflected diffusely, resulting in a decrease in light transmittance, and when the filter is incorporated as a color filter into an optical display, a decrease in color contrast is observed. Further, in the color filter manufacturing process, various chemical treatment steps are performed, but there is a drawback that the printed portion has poor chemical resistance to certain types of chemicals.

In addition, as is common with conventional color filters manufactured using the photolithography method, if the filter is not handled with care, it may cause scratches on the film surface, resulting in a defective product. A solution is desired.

(Object of the Invention) The present invention has been made in view of the above circumstances, and aims to smooth the surface of the colored film of a printed color filter, improve spectral transmittance and chemical resistance, and improve weather resistance. It is an object of the present invention to provide a color filter which has excellent color properties and improved ease of handling of the filter itself.

(Summary of the Invention) The present invention provides a smooth overcoat layer on the printed colored film surface of a color filter formed on a transparent substrate by a printing method. By preventing the diffusion and diffuse reflection of light, it improves the color contrast (chromaticity) between each color such as the three primary colors of R, G, and B formed on the filter, and also improves the abrasion resistance and chemical resistance of the colored film. It is something that improves.

(Specific Means for Solving the Problems) The present invention provides a transparent colored ink coating (1) on a transparent substrate (1) such as glass as shown in FIG.
2), and an overcoat layer (3) of a transparent film made of a photo- or thermosetting resin and having a smooth surface is provided on the surface of the film.

(Detailed description of the invention) The present invention will be explained in detail below.

For example, as shown in FIG. 2(a), printing method color filters are produced by first transferring the color ink pattern (6) in the ink cells (5a) of the intaglio plate (5) onto the blanket (4), and then printing as shown in FIG. 2(a). Transparent substrate (1) which is the printing material as shown in b)
The ink pattern (6) transferred to the blanket is retransferred onto the blanket to form a colored ink film (2). Depending on the type and material of the blanket (4) or the transparent substrate (1) to be printed, the blanket (4)
When transferring the ink pattern (6) to the substrate (1), the color ink pattern (6) was not 100% transferred, and the ink pattern (6) was divided into the blanket (4) and the substrate (1) sides. Then, the splitting plane forms a substrate with the uneven surface as the surface (
Transferred to 1〉. Therefore, fine irregularities caused by splitting of the ink layer remain on the surface of the colored ink film (2) of the ink pattern (6) printed on the substrate (1).

For example, in the case of 100% transfer, the fine irregularities on the surface of the blanket (4) will be reproduced on the surface of the ink pattern (6) transferred to the substrate (1), resulting in an opaque feeling similar to printing on frosted glass. A colored ink coating (2) of an ink pattern (6) is printed on the substrate (1). After this colored ink film (2) is completely cured by evaporation treatment of the ink solvent contained in the film or by oxidative polymerization drying, a transparent resin thin film is overlaid to embed the fine irregularities of the ink film (2). A color filter is obtained by providing a coating layer (3).

Overcoat layer (3) in the color filter of the present invention
), conventionally used coating methods such as spinner coating and roll coating can be applied, but it is preferable to obtain a coating film that is as thin and uniform as possible to the extent that unevenness can be smoothed out. There is a spinner coating gravity method that can be used.

The transparent resin used for coating is preferably a liquid type, colorless and transparent, and any curing method may be used, such as room temperature curing, heat curing at 250'C or less, ultraviolet curing, radiation curing, etc. .

This transparent resin has a transparent coating film, good adhesion to printing ink, and chemical resistance, especially acetic acid, n,
It is required to have resistance to N-methyl 2-pyrrolidone and high hardness of the cured surface.

In general, acrylic resins are examples of resins that satisfy these characteristics, but the resin is not particularly limited to this resin, and any resin may be used as long as it satisfies the above characteristics.

By overcoating such a liquid transparent resin onto a printing color filter and curing it. , 1 μm generated on the surface of the color ink pattern on the transparent substrate
The following fine irregularities can be filled with the transparent resin to smooth the surface of the color ink pattern and prevent diffuse reflection of incident light.

In the present invention, as the resin for forming the overcoat layer (3) on the colored ink film (2), in addition to the above-mentioned liquid type, a thin film of thermoplastic acrylic resin is used to coat the colored ink film (2). After that, the colored ink film (2) is laminated under heat and pressure to fill in the unevenness of the colored ink film (2).

(Operation of the invention) As a result, the light transmittance of the color filter increases, and red (
The spectral transmittance of each of R), green (G), and blue (B) is improved compared to when no coating layer (3) is provided, and the overcoated transparent resin provides a protective film against processing chemicals and friction. As a result, the chemical resistance and abrasion resistance of printed color filters are improved.

Figure 3 shows a comparison of the spectral transmittance of the color filter colored film formed by the printing method before and after the overcoat treatment, and shows the three primary colors of light, blue (B) and green (G
), the light transmittance of each color of red (R) shows an increasing effect near its maximum value, and no change is seen at the minimum value, so the saturation and brightness of each color increase, and the mutual contrast between each color increases. An improvement was seen.

In addition, a comparison of chemical resistance before and after overcoat treatment is shown in Table 1 below.

Table-1 Surface condition of colored ink film by ultrasonic cleaning; Temperature:
Room temperature time: 5 minutes Test machine: Ultrasonic cleaner (Pet cleaner 52.35'
? , ', 41KH2) 91 In the present invention, by improving the smoothness of the colored film, when forming a transparent conductive film such as an ITO film or an electrode pattern on the surface of the color ink pattern by vapor deposition, the surface of the ink pattern can be improved. Problems such as disconnection of the electrode pattern and changes in resistance caused by the unevenness of the electrode pattern are also solved, and the edge shape of the electrode pattern becomes sharp. In addition, by using a photosensitive resin as the transparent resin for overcoating, after overcoating the entire surface of the color ink pattern of the printing method color filter with the photosensitive resin, a negative or positive mask pattern is overlaid and exposed. A resin pattern of a desired shape can be formed by curing and developing with a developer. As a result, the liquid crystal is sealed between the color ink pattern surface of the printing method color filter and the glass substrate with the counter electrode pattern, and the transparent resin for the sealing part is selected to improve the seal adhesion effect when sealing. This makes it possible to remove them.

Furthermore, it is also possible to selectively overcoat the color ink patterns of the three primary colors of blue, green, and red.
The light transmittance of only a desired hue can be improved.

(Effects of the Invention) The present invention involves forming a film on a transparent substrate using colored ink to form a desired filter pattern, and overcoating the film with a transparent resin. This printing method color filter eliminates the reduction in light transmittance that occurs due to the disadvantages of manufacturing, and improves the color reproducibility of color display images on liquid crystal display devices, and improves the saturation and brightness of the three primary colors. It can be improved even more than conventional printing method color filters, and the effects obtained are extremely remarkable, such as improving the efficiency of the filter assembly process in the production of optical electron beam curable resin parts and expanding the scope of application of chemical processing and handling. There is something.

<Example 1> Liquid type thermosetting acrylic resin H3 (viscosity 1.5
C1), manufactured by Osaka Organic Chemical Industry Co., Ltd.) using a normal spinner coating device (rotation speed (2000 rl) m, coating time 1 minute), intaglio offset printing of blue, green, and red ink coating thickness of 2 to 3 μm). This was coated onto the printed surface of the patterned printed filter, and heat-cured at 170'C for 11 hours to obtain a coating film thickness of 0.6 μm.

As a result, a transparent appearance was obtained on the printed surface of the filter, improvement in saturation and brightness was observed in each color tone, and the difference in hue between each color became clear. When the spectral transmittance of each color was measured before and after coating, it was found that the transmittance improved by about 4%. (Figure 3) In addition, no damage was observed especially to the surface of the colored coating of the filter, even with chemicals containing acetone and N-methyl 2-pyrrolidone.
The abrasion resistance also did not require particularly careful operation, and a good scratch prevention effect was obtained even during normal processing operations.

<Example 2> Ultraviolet curable acrylic resin FVR (viscosity 75 Cp, manufactured by Fuji Pharmaceutical Co., Ltd.) was coated on the surface of the printed filter on which the colored ink film had been formed in the same manner as in Example 1 using a subina coater (rotation speed 200Qr). pm, application time 1 minute), and ultra-high pressure mercury lamp (output 1 am, distance 1 m>).
The film surface was cured by irradiating ultraviolet rays for ~5 minutes to obtain a film thickness of approximately 1 μm.

As a result, the spectral transmittance, chemical resistance, and surface abrasion resistance of the colored filter were improved.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view of the color filter of the present invention, FIG. 2 is a schematic diagram of the colored ink film transfer state by the printing method of the present invention, and FIG. 3 is a graph showing fluctuations in spectral transmittance.

Claims (6)

[Claims] (1) A color filter characterized by forming a transparent colored ink film on a transparent substrate such as glass, and providing an overcoat layer of a transparent thin film made of light or thermosetting resin with a smooth surface on the surface of the film. . (2) The filter according to claim 1, wherein the colored ink film is mainly composed of acrylic or epoxy varnish and has a thickness of 2 to 3 μm and is formed by screen printing or intaglio offset printing. (3) The filter according to claim 1, wherein the overcoat layer is a liquid type ultraviolet curable acrylic resin. (4) The filter according to claim 1, wherein the overcoat layer is a liquid type thermosetting acrylic resin. (5) The filter according to claim 1, wherein the overcoat layer is a film-like acrylic resin. (6) The filter according to any one of claims 1 to 5, wherein the thickness of the overcoat layer above the colored ink film is 1 to 0.5 μm or less.