JPH08220327A - Color filter - Google Patents

Abstract

PURPOSE: To provide a color filter having high flatness and reliability by providing a thin film having a specific film thickness on a colored layer. CONSTITUTION: The color filter is provided with a light shielding layer and a coloring layer on a transparent substrate. As the light shielding layer, metal chromium, molybdenum, tantalum, aluminum or these oxides or a resin, in which a black pigment is dispersed, is used. As the colored layer, a mixture prepared by dispersing a dye or pigment in an acrylic resin, a polyester resin, a polyvinyl alcohol resin or a polyimide resin is used. As the thin film provided on the colored layer, an acrylic resin, an epoxy resin, a polyimide resin, a silicone resin or the like is used. Particularly the polyimide resin consisting of a polymer expressed by a formula as a main structural unit is preferable. It is important for the thin film to have <=0.5μm film thickness. When the film thickness exceeds 0.5μm, an ITO formed thereon is easily strippable by the stress strain in orientation process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter used for a liquid crystal display device, a solid-state image pickup device and the like.

[0002]

2. Description of the Related Art Color filters used in liquid crystal display devices and the like have red (R), green (G), and blue (B) on a transparent substrate.
The structure has a light-shielding substance around the colored layer and each color part. A transparent protective film is generally formed on the colored layer for the purpose of surface protection and flattening.

Currently, as a transparent protective film, an acrylic resin (JP-A-3-251819) and an epoxy resin (JP-A-2-228630) are used.
JP-A-61-254905), silicone resin (JP-A-63-241076), imide-modified silicone (JP-A-63-291924) and the like. These transparent protective films have a thickness of 1 μm for flattening.
A film of m or more is formed.

[0004]

However, these transparent protective films have poor adhesion to the underlying transparent substrate, the colored layer and the light-shielding layer, and are colored slightly so that the color filter However, there is a problem that the transparency (1) is lowered and the thermal expansion coefficient of the protective film is not appropriate, so that the ITO (transparent electrode layer) formed on the protective film is peeled off due to stress strain in the alignment film treatment step. Further, by adding a transparent protective film, the number of steps for manufacturing the color filter is increased, which not only increases the cost but also
There is also a problem in production that the number of defective products increases and the yield deteriorates. For this reason, it is often practiced to directly attach the transparent electrode on the colored layer excluding the transparent protective film. However, since the flatness of the surface is rather poor, there are problems that the resistance of the transparent electrode is increased, the alignment film is misaligned, and the ionic impurities from the colored layer adversely affect the liquid crystal display device.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have earnestly studied and arrived at the present invention.

That is, the present invention is characterized in that a thin film having a thickness of 0.5 μm or less is formed in a color filter in which a light shielding layer and a coloring layer are provided on a transparent substrate. With such an arrangement, the drawbacks of the conventional transparent protective film are improved, and a highly reliable and low cost color filter can be obtained.

In the color filter of the present invention, a colored layer and a thin film are provided in this order on a transparent substrate, and a transparent electrode layer of indium tin oxide or the like is usually formed thereon.

The transparent substrate is not particularly limited, but a glass plate such as alkali glass or non-alkali glass or a resin substrate such as polycarbonate or polymethacrylate can be used. 7059 among these
(Corning Corporation), OA2 (Nippon Electric Glass), NA40
Alkali-free glass such as (HOYA) is preferable in terms of alkali elution, heat resistance, chemical resistance, cleanliness and the like.

Although the colored layer is not particularly limited,
Acrylic resin, polyester resin, polyvinyl alcohol resin, polyimide resin and the like, or a mixture of two or more kinds thereof, and a colorant such as a dye or a pigment are dispersed and mixed in these photosensitive resins to form red, blue and green pixels. The formed one is used. As a method for forming the colored layer, a dyeing method, a pigment dispersion method, a transfer method, a printing method, an electrodeposition method or the like can be appropriately used.

A light-shielding layer made of metal, resin, or the like is provided between the pixels as needed to improve the contrast. Specifically, metallic chromium, chromium oxide,
Resins in which molybdenum, tantalum, aluminum and oxides thereof, carbon, and black pigment are dispersed are used. Among these, metallic chromium and chromium oxide are preferable in terms of light-shielding properties and film forming properties.

In the present invention, the thin film usually acts as a transparent protective layer. As the thin film, a known resin such as an acrylic resin, an epoxy resin, a polyimide resin, or a silicone resin may be appropriately used, but a polyimide resin is preferable, and a particularly preferable one is the following general formula:

Embedded image It is a resin containing the polymer represented by as a main constituent unit. In the above general formula, R ¹ is a trivalent or tetravalent organic group having at least 2 carbon atoms. From the heat resistance of the polyimide resin, R ¹ preferably has a structure in which the bond with the carbonyl group of the polymer main chain is directly formed from an aromatic ring or an aromatic heterocycle. In the above general formula, R ² is a divalent organic group having at least 2 carbon atoms. From the heat resistance of the polyimide resin, R ²
Is preferably one having a structure in which the bond to the amide group of the polymer main chain is directly formed from the aromatic ring.

Specific examples of this polyimide resin include pyromellitic dianhydride and 3,3'- (or 4,4 '
-) Diaminodiphenyl sulfone, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, and 3,3'- (or 4,4'-) diaminodiphenyl sulfone, 3,3', 4,
4'-biphenyltetracarboxylic dianhydride and 3,3'-
(Or 4,4'-) diaminodiphenyl sulfone, pyromellitic dianhydride and 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3'- (or 4,4 '
-) Diaminodiphenyl sulfone, 3,3 ', 4,4'-benzophenone tetracarboxylic acid anhydride, and 3,3'- (or,
4,4 '-) diaminodiphenyl sulfone and bis (3-aminopropyl) tetramethyldisiloxane, 3,3', 4,
4'-benzophenone tetracarboxylic anhydride and 3,3'-
(Or 4,4'-) diaminodiphenyl sulfone and
It is preferable to use a polyamic acid synthesized from 3,3′-diaminodiphenylmethane, bis (3-aminopropyl) tetramethyldisiloxane, etc. as a polyimide resin by heating or the like. The polyimide resin may be composed of only one represented by the above general formula, or may be a copolymer with another structural unit. The types of structural units used for copolymerization include polyether amic acid,
The structural unit of polyester amic acid is mentioned as a typical example, However, It is not limited to these. The thin film can be applied by any method such as a spinner method, a roll coater method, a printing method and a dipping method.

In the present invention, it is important that the thickness of this thin film be 0.5 μm or less. This is because when the film thickness exceeds 0.5 μm, the coefficient of thermal expansion of the thin film and the ITO (transparent electrode layer) formed on it is not appropriate, and peeling of ITO occurs due to stress distortion in the alignment film treatment process, and low wavelength (400-500nm)
This is because the transparency on the side is reduced and the brightness of the blue pixel is reduced. When the film thickness is 0.5 μm or less, the ITO film does not peel off because the thermal expansion coefficient has almost no effect due to the thin film thickness, the decrease in transparency on the low wavelength side is small, and the blue pixel also has sufficient brightness. are doing. Further, although the number of steps is increased by one as in the case of forming the transparent protective film, the processing amount is considerably small and the cost is reduced to less than half. As described above, it is preferable that the thickness of the thin film is thin. However, if the thickness is less than 0.01 μm, it is difficult to flatten the surface roughness of the colored layer. Therefore, the thickness is preferably 0.01 to 0.5 μm.

These thin films are thinner than ordinary surface protective films, but ITO is used to smooth the surface of the colored layer.
Does not cause a high resistance and defective orientation of the alignment film, and has sufficient barrier properties against ionic impurities, so that there is no adverse effect on the liquid crystal display device.

In the present invention, the thin film may be formed on the entire surface of the color filter, but it is preferably provided in the region where at least one of the light shielding layer and the coloring layer exists. This is TF
Epoxy resin or the like is mainly used as the material of the seal portion, which is a portion to be bonded to the T substrate, but it may be better to be in direct contact with the glass through the thin film to improve the adhesion. Most ideally, it is more preferable that the thin film is formed so as to exactly overlap the region where at least one of the light shielding layer and the coloring layer is present. However, even when the thin film is formed outside the region where at least one of the light-shielding layer and the coloring layer exists, the effect is achieved as long as it is in the vicinity of the outside, so that at least one of the light-shielding layer and the coloring layer exists. It is included in the range of the area.

The method of forming the thin film inside the region where at least one of the light-shielding layer and the colored layer of the color filter is present is not particularly limited. For example, the thin film is formed on the transparent substrate on which the light-shielding layer and the colored layer are formed. Is formed in a region where at least one of the light shielding layer and the colored layer exists. Specifically, for example, after applying a thin film on the entire surface of a transparent substrate having a light-shielding layer and a colored layer formed thereon, the thin film outside the region where at least one of the light-shielding layer and the colored layer of the color filter is present is removed. Obtained by As a removal method, for example, there is a photolithography method. After coating the entire surface, the solvent is removed in an oven and a resist is applied on the semi-cured polyimide resin and prebaked, and then exposure is performed using a mask having a predetermined pattern. Since the polyimide resin is etched by the alkaline liquid that develops the resist, development and etching can be performed simultaneously. When the resist is soaked in an alkaline solution that is also a developing solution, that is, an etching solution, the solubility of the resist in alkali becomes extremely large, and the removed polyimide resin is etched. The polyimide resin is immersed in an alkaline solution (for example, MP351 manufactured by Shipley Co., Ltd., diluted with pure water to a volume of 5% to 50%) at 25 ° C. for about 15 seconds to 30 seconds. For development etching with an alkaline solution, a dipping method, a spray method, or the like can be used. The temperature of the developing solution can be used at a temperature at which over-etching or under-etching does not occur in consideration of the developing speed, but 10 ° C to 50 ° C is preferable.
Next, MCA (methyl cellosolve acetate), ECA
The resist is stripped with an appropriate solvent such as (ethyl cellosolve acetate), PGMEA (propylene glycol monomethyl ether acetate) and butyl acetate. Thus, the polyimide resin is formed inside the region where at least one of the light shielding layer and the coloring layer of the color filter exists.

In order to form the thin film inside the region where at least one of the light-shielding layer and the coloring layer of the color filter exists, a method of applying only a predetermined portion by a die coater method, a roll coater method or a printing method is used. It is also possible. The die coater method can be applied to the inside of the color filter forming region using slot coating, curtain coating, slide coating or the like with a slit die. The roll coater method can be applied using either a natural coater or a reverse coater. In the printing method, flexo printing (topographic printing), screen printing,
Although planographic printing, intaglio printing and the like can be used as appropriate, the flexographic printing method and the screen printing method are preferable because the material design of the coating film is easy.

As described above, by forming a thin film on a color filter according to the present invention, the conventional transparent protective film having peeling of ITO due to a difference in thermal expansion from ITO and deterioration of transparency is provided. Not only can the problems be improved, but the cost can be reduced to less than half, and productivity can be improved.

[0019]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to the examples.

Reference Example 1 (Formulation of Polyimide Resin) N-methyl-2-pyrrolidone 614 [g] was placed in a three-necked 2 liter flask, and 3,3'-diaminodiphenyl sulfone 49.65 was added while stirring under nitrogen bubbling.
[g] and 4,4'-diaminodiphenylmethane 39.66 [g] are added. After stirring for 20 minutes, 126.16 [g] of 3,3 ', 4,4'-benzophenone tetracarboxylic acid anhydride was added to a small amount of N-methyl-2-
It is gradually added together with pyrrolidone, and when completely dissolved, the temperature is raised to 50 ° C. The mixture was stirred for 3 hours while controlling the temperature at 50 ° C. To prepare the terminal, 1.66 [g] maleic anhydride was added, and the mixture was further stirred for 1 hour. After standing at room temperature for a whole day and night, it was diluted with a mixed solvent of N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether to a solid content concentration of 11 [%] to obtain a polyamic acid varnish as a polyimide precursor.

Example 1 (Production of Color Filter) A color filter was produced as follows.

A patterned metallic chromium light-shielding layer was provided on a transparent substrate, and a colored polyimide layer containing a heat resistant pigment was patterned by photolithography. The polyamic acid varnish prepared in Reference Example 1 was applied as a thin film thereon by a spinner. Then in an oven at 100 ° C 1
It was put in for 0 minutes and dried. The film thickness was set to be about 0.1 μm after drying. In addition, 30 in an oven at 300 ℃
The main curing was performed for a minute to completely cure. Finally, ITO was formed by sputtering deposition to manufacture a color filter.

Example 2 A patterned metallic chromium light-shielding layer was provided on a transparent substrate, and a colored polyimide layer containing a heat resistant pigment was patterned by photolithography. The polyamic acid varnish prepared in Reference Example 1 was applied as a thin film thereon by a spinner. Then, it was put in an oven at 100 ° C. for 10 minutes to be dried. The film thickness was set to be about 0.1 μm after drying. Further, a resist (“Microposit” RC-100 series manufactured by Shipley Co., Ltd.) is dried on the semi-cured adhesion layer with a spinner to a film thickness of 1 to 2 μm, and prebaked in an oven at 90 ° C. for 10 minutes. I went. The adhesion layer was formed only in the pixel portion and the frame chrome portion, and patterning was performed as follows to remove the adhesion layer on the glass portion. A patterned mask is placed on the substrate for exposure, and then pure water is added to alkali (MP351, Shipley Co., Ltd.) to make the capacity 16.7%.
The above developing solution was immersed at 25 ° C. for 30 seconds. Development and etching of the adhesion layer were performed in this developer. Next, the remaining resist was removed using a stripping agent (methyl cellosolve acetate). Further, after semi-curing in an oven at 100 ° C. for 10 minutes, main curing was performed in an oven at 300 ° C. for 30 minutes to completely cure the protective layer. Finally, ITO was formed by sputtering deposition to manufacture a color filter.

Comparative Example 1 A color filter was manufactured in the same manner as in Example 1 except that a polyimide film was applied onto the colored layer by a spinner so as to have a thickness of 1.0 μm.

Comparative Example 2 A color filter was manufactured in the same manner as in Example 1 except that an acrylic resin film was applied on the colored layer by a spinner so as to have a thickness of 1.0 μm.

Comparative Example 3 A color filter was manufactured in the same manner as in Example 1 except that ITO was sputter-deposited directly on the colored layer to form neither a transparent protective film nor a thin film.

Example 3 With respect to the color filters produced in Examples 1 and 2 and Comparative Examples 1 and 2, the transparency retention rate and the ITO resistance value were measured. The results are shown in Table 1.

In addition, in order to cure the alignment film after applying the alignment film made of a polyimide resin on the color filters produced in Examples 1 and 2 and Comparative Examples 1 and 2 by a flexographic printing method. It was heated at 280 ° C., and the ITO adhesion at the time of forming the alignment film was observed. The results are shown in Table 1.

[0029]

[Table 1]

Regarding the transparency, in Comparative Examples 1 and 2, the transmittance on the low wavelength side was low and the blue brightness was low. Further, in the case of Comparative Example 3, the surface was not flattened because there was no film on the colored layer, and ITO was directly formed.
Disconnection occurred. Therefore, the resistance value of ITO was as high as 50Ω. Regarding the ITO adhesion when forming the alignment film,
Although there is no problem in Examples 1 and 2 and Comparative Example 1, in Comparative Example 2, peeling occurred in ITO due to the difference in thermal expansion coefficient between ITO and the acrylic resin that is the transparent protective film.

[0031]

According to the present invention, a thin film having a thickness of 0.5 μm or less is formed on the colored layer, which is different from the film thickness level of a general transparent protective film. Moreover, the ITO does not peel off when the alignment film is formed. ITO also has low resistance. In this way, a highly reliable low cost color filter can be obtained.

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[Procedure amendment]

[Submission date] April 17, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

A light-shielding layer made of metal, resin, or the like is provided between the pixels as needed to improve the contrast. Specifically, metallic chromium, chromium oxide,
Resins in which molybdenum, tantalum, aluminum and oxides thereof, carbon, and black pigment are dispersed are used. Among them, metallic chromium , chromium oxide, carbon, and black pigment are dispersed due to their light-shielding property and film-forming property .
Resin and the like are suitable.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

In the present invention, the thin film may be formed on the entire surface of the color filter, but it is preferably provided in the region where at least one of the light shielding layer and the coloring layer exists. This is TF
Epoxy resin or the like is mainly used as the material of the seal portion, which is a portion to be bonded to the T substrate. However, it may be better if the glass and the seal portion are in direct contact with each other through a thin film. is there. Most ideally, it is more preferable that the thin film is formed so as to exactly overlap the region where at least one of the light shielding layer and the coloring layer is present. However, even in the case of forming up to the outside of at least one of the presence area of the thin light shielding layer and colored layers, a near outside, remaining in the periphery region that does not form a film
If so, the effect can be achieved, so that it is included in the range of the region where at least one of the light-shielding layer and the coloring layer exists.

Claims (4)

[Claims] 1. A color filter in which a light-shielding layer and a colored layer are provided on a transparent substrate, wherein a thin film having a thickness of 0.5 μm or less is formed on the colored layer. 2. The color filter according to claim 1, wherein a thin film having a film thickness of 0.01 to 0.5 μm is formed on the transparent coloring layer. 3. The thin film is in a region where at least one of the light-shielding layer and the coloring layer is present.
Color filter as described. 4. The color filter according to claim 1, wherein the thin film is made of a polyimide resin.