JPH0882708A - Color filter and manufacturing method thereof - Google Patents

Abstract

PURPOSE: To decrease the amt. of necessary dyes while maintaining characteristics of dyes as a coloring agent by using polyimide having high transparency and colored polyimide according to the color required. CONSTITUTION: Dyes are used as a coloring agent and polyimide resin is used as the resin material for filter pixels. A first type polyimide which is colored in the resin itself is used for at least one group of red and green filter pixels in the filter pixels of red, green and blue colors. A second type polyimide having high transparency than that of the first polyimide is used for the blue filter pixels. The first polyimide is a normal aromatic polyimide which shows yellowish color, while the second polyimide is another polyimide having improved transparency, for example, a transparent polyimide in which part of aromatic groups are replaced by other groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming filter pixels of a color filter with a polyimide resin, and more particularly to a technique for effectively utilizing different types of polyimide.

[0002]

BACKGROUND OF THE INVENTION As one of color filters used for color display of a liquid crystal display or the like, a plurality of groups of filter pixels having different spectral characteristics of red, green and blue are provided on a substrate such as glass or plastic, and each group is provided. Is known that the filter pixel includes a polyimide resin and a colorant (dye or pigment) mixed in the resin (for example, Japanese Patent Publication No. 4-243 or JP-A-60-247).
References such as 603). This type of color filter is excellent in various resistances such as heat resistance and light resistance, which is considered to be due to the characteristics of the polyimide resin. However, there are many types of polyimide-based resins, and depending on the presence or absence of high transparency, for example, the first type of polyimide in which the resin itself has a tint, such as general aromatic polyimide, has a higher transparency. It can be halved into a transparent type polyimide. In general, transparent type polyimide tends to be used as the polyimide resin from the viewpoint of the color characteristics of the color filter (for example, see JP-A-60-184203). Further, the usual aromatic polyimide-based resin has insufficient adhesion to the substrate such as glass, and in this case, in order to obtain sufficient adhesion to the substrate such as the aromatic polyimide-based resin and glass, It is necessary to pretreat a substrate such as glass with a silane coupling agent in advance. Incidentally, the term "sufficient adhesion" as used herein means a state where no peeling of the aromatic polyimide resin from a substrate such as glass is observed at all as a result of a cross-cut (cross-cut) test using cellophane tape. Say.

[0003]

On the other hand, there are dyes and pigments as colorants that are mixed in a polyimide resin to color the resin. The pigment has excellent chemical resistance and heat resistance as compared with the dye, but on the other hand, it is difficult to disperse the pigment uniformly in the resin, and therefore, a dispersant for dispersion must be usually added. In that respect, since the dye is dissolved in a solvent that dissolves the precursor of the polyimide resin, a uniform color can be easily obtained and the transparency is excellent. However, the dye is essentially easy to elute in the solvent, and the elution becomes more remarkable as the content ratio of the dye to the resin increases,
Further, considering the mass production of color filters, it is required to reduce the amount of expensive dyes used as much as possible and to suppress the cost of color filters. Therefore, the inventors have conceived the present invention in consideration of using a dye as a colorant and reducing the usage amount (content) of the dye as much as possible.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique capable of reducing the use amount of a dye as much as possible while taking advantage of the advantage of using the dye as a colorant. Another object of the present invention is to provide a technique capable of responding to various characteristics required for a color filter, particularly color characteristics and adhesion to a substrate, by selectively using different types of polyimide.

[0005]

In the present invention, a dye is used as a colorant, and
While using polyimide resin as the resin material of the filter pixel, red, green, and blue of the three filter pixels of red,
At least one group of greens is formed by using the first type polyimide whose resin itself has a tint, while the remaining blue filter pixels are formed by the second polyimide having a higher transparency than the first type polyimide. Try to use the type of polyimide. As the first type of polyimide, a normal yellowish aromatic polyimide can be applied,
Further, as the second polyimide, another polyimide having improved transparency, for example, a transparent polyimide in which a part of the aromatic group is changed to another group, or having a siloxane structure inside, has transparency and glass. Silicon polyimide having improved adhesion with can be applied.

As a method of manufacturing the color filter, a printing method, a photolithography technique, or a combination thereof can be applied. In the case of the combination, for example, the light shielding pattern located at the boundary of each filter pixel can be formed by the photolithography technique, while the filter pixel located inside thereof can be formed by printing. But,
From the viewpoint that high patterning accuracy can be obtained, it is preferable to form each filter pixel by a photolithography technique. When forming each red, green, and blue filter pixel (and in some cases, a black light-shielding pattern) by photolithography technology, improve the adhesion between the polyimide, which is the main component of each filter pixel, and the glass of the substrate. is necessary. In this respect, it is preferable to use a resin containing silicon polyimide as at least the polyimide resin of the first color filter pixel to be formed. Because the resin containing silicon polyimide /
When a polyimide coating liquid consisting of a dye as a colorant / other additives (for example, a silane coupling agent for improving adhesion or a surface modifier) is applied on the substrate, the surface of the substrate is coated with silicon polyimide. Is modified so that the colored coating film for forming the color pixels of the second and subsequent colors comes into close contact with the substrate. The first color polyimide resin may be made by blending silicon polyimide and another polyimide (for example, aromatic polyimide), but in order to effectively modify the surface, for example, another polyimide is On the other hand, it is preferable to set the silicon content to 1.0% or more in terms of the weight ratio of the solid content of all the polyimide-based resins, for example, by setting the blending amount of silicon polyimide to 4 or more. Thereby, sufficient adhesion can be obtained.

[0007]

[Action] Aromatic polyimide has a yellowish tint,
When a pigment is used as a colorant, the problem of turbidity may occur. This is because the pigment itself is inferior in transparency to the dye. However, when using a dye with excellent transparency as a colorant, there is no problem of such turbidity,
On the contrary, the addition amount of the dye required for coloring can be reduced depending on the tint of the resin itself. For example, cyan and yellow dyes are blended and used as a colorant for a green filter pixel, but the amount of yellow dye added can be reduced by, for example, about 10 to 20% depending on the yellowness of the resin. The same applies to the red filter pixel that blends the yellow dye and the red dye. On the other hand, for a blue filter pixel that does not use a yellow dye, a preferable blue color characteristic can be obtained by using another highly transparent polyimide. Further, when sequentially patterning the filter pixels of each color by the photolithography technique, when a polyimide containing silicon polyimide is used as the first-color polyimide to be formed first, the surface of the glass substrate is coated by applying the first-color polyimide. It can be modified. As a result, when the filter pixels of the second and third colors are formed, the adhesion between the colored coating film for forming the pixels of each color and the substrate is improved. Therefore, no pretreatment is required to improve the adhesion.

[0008]

[Preferred embodiment]

When forming three groups of filter pixels of red, blue and green on a glass substrate, the following materials were used as coating materials for the respective filter pixels. a. Coating material for red 1: A transparent silicone polyimide precursor solution with a solid content of 27% and an aromatic polyimide precursor solution with a solid content of 21% are 1:
Dissolve the mixture in the ratio of 1 in methyl cellosolve,
To the solution, an acid dye-based red dye, a metal-containing complex salt azo-based yellow dye, a silane coupling agent and a surface modifier having a perfluoroalkyl group as one component were added to prepare a red coating liquid. The silicon content of the coating liquid at this time was 2.8% in terms of the weight ratio of the solid content of all polyimide precursors. b. Blue coating material A transparent silicon polyimide precursor solution having a solid content of 27% is dissolved in methyl cellosolve, and a plurality of triphenylmethane-based blue dyes are added to the solution, and silane is used in the same manner as the above red coating material. A coupling agent and a surface modifier containing a perfluoroalkyl group as one component were added to prepare a blue coating solution. The silicon content of the coating liquid at this time was 1.3% by weight ratio of the solid content of all polyimide precursors. c. Coating material for green Aromatic polyimide precursor solution having a solid content of 21% is dissolved in methyl cellosolve, and the solution contains a metal complex salt azo yellow dye, Acid Blue 9 and the like, and the same as the coating material for red described above. A silane coupling agent and a surface modifier containing a perfluoroalkyl group as one component were added to the mixture to prepare a green coating solution. The coating liquid at this time does not contain silicon. The amount of the dye in the coating material for green was 0.48% for the yellow dye of the metal-containing complex salt azo type, and 0.1% for Acid Blue 9 or the like, based on the weight ratio of the solid content of the aromatic polyimide precursor.
Including 17%, the total dye amount was 0.65%.
For example, at this time, if an attempt is made to reproduce the same color tone by using a transparent silicon polyimide precursor solution having a solid content of 27% as the green coating material without using an aromatic polyimide precursor solution having a solid content of 21%, 0.63% of a metal-containing complex salt azo yellow dye and 0.16% of Acid Blue 9 and the like, based on the weight ratio of the solid content of the silicon polyimide precursor,
The total dye amount was 0.79%. Therefore,
As described above, when the yellowish aromatic polyimide was used, the amount of the dye added could be reduced by about 18% as compared with the case where the transparent silicon polyimide precursor was used. These were patterned in the order of red-blue-green. Each patterning includes a step of applying a coating material on a glass substrate and a step of patterning the resulting polyimide coating layer by a conventional method using a photoresist.

According to the color filter of the embodiment, when forming the green filter pixel, the addition amount of the yellow dye is 1 when compared with the case where the transparent type polyimide is used.
It was possible to reduce it by about 0 to 20%, and the resistance of the green filter pixel could be improved accordingly. Also, since the coating material for the first color of red contains silicon polyimide, the surface of the glass substrate is modified according to the coating,
Even when the second and third colors are applied, the colored coating film for forming the color pixels and the substrate are brought into close contact with each other without any pretreatment, and, in combination with the silane coupling agent, sufficient adhesion strength is obtained. I was able to get it. Furthermore, in the embodiment,
Since the filter pixels are formed in the order in which the heat resistance of the dye is high, the color characteristics of the filter pixels are not impaired even though the heat treatment is performed at a high temperature for each patterning.

[0011]

According to the present invention, a highly transparent polyimide and a tinted polyimide are selectively used according to each color, so that the characteristics of the dye as a colorant (particularly the color characteristics and the color It is possible to slightly reduce the required dye while making good use of (uniformity), thereby further improving the chemical resistance of the colored coating film and reducing the cost of the color filter. Also,
When forming filter pixels of each color by photolithography technology, the resin of silicon polyimide is used as the polyimide resin of the first-color filter pixel to be formed first, so that the surface of the substrate is modified without pretreatment of the substrate. It is possible to improve the adhesion of the colored coating film to the substrate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryohei Okamoto 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Kyodo Printing Co., Ltd.

Claims (5)

[Claims] 1. A substrate is provided with a plurality of groups of filter pixels having different spectral characteristics of red, green, and blue, and each group of filter pixels includes a polyimide resin and a colorant mixed in the resin. In a color filter including, the colorant is a dye, the first type of polyimide resin itself has a tint is used as the polyimide resin of at least one of the red and green filter pixels, while the blue filter is used. A color filter characterized in that a second type polyimide having a higher transparency than the first type polyimide is used as the polyimide resin of the pixel. 2. The color filter according to claim 1, wherein the first type of polyimide is an aromatic polyimide. 3. The aromatic polyimide has a yellow tint,
The color filter according to claim 1, wherein the amount of yellow dye added is correspondingly small. 4. A substrate is provided with a plurality of groups of filter pixels having different spectral characteristics of red, green, and blue, and each group of filter pixels includes a polyimide resin and a colorant mixed in the resin. In the method of manufacturing a color filter in which the filter pixels of each group are sequentially formed for each color by a photolithography technique, the colorant is a dye, and the red and green are at least one group of the filter resin as a polyimide resin. , While the resin itself uses an aromatic polyimide having a tint, a transparent type polyimide having a higher transparency than the aromatic polyimide is used as the polyimide resin of the blue filter pixel, and at least first formed. A resin containing silicon polyimide is used as the polyimide resin for the first color filter pixel. And a method of manufacturing a color filter. 5. The method of manufacturing a color filter according to claim 4, wherein the substrate is a glass substrate, and a silane coupling agent is further included in the filter pixel of each color.