JPH05119214A - Substrate with color filter and production thereof and liquid crystal display body formed by using this substrate - Google Patents

Abstract

PURPOSE:To obtain the substrate which is uniform in the thickness of color filter layers, has the high boundary linearity or shape accuracy of the color filters and has high brightness as the color filters by constituting the substrate of a porous layer which is provided on the substrate and consists mainly of pseudobaimite and coloring materials which are held in the porous layer. CONSTITUTION:The porous layer 11 mainly consisting of the pseudobaimite is provided on the substrate 10 and striped filters consisting of pigment dispersed ink parts 12 are formed by offset printing. The solvent in the pigment dispersed ink evaporates and diffuses into the pores of the porous layer 11 mainly consisting of the pseudobaimite structure. Then, the viscosity of the pigment dispersed ink increases and the ink layer is relatively securely stuck by an anchor effect and, therefore, the linearity of the stripes of the color filters and the shape accuracy of dots are improved. The substrate to be used is not particularly limited and is exemplified by org. sheets of, for example, polyethylene terephthalate, polyester, diacetate, etc., and various kinds of glass plates, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate with a color filter in which a coloring material is held in a porous layer, a method for producing the same and a liquid crystal display using the same.

[0002]

2. Description of the Related Art In recent years, a light receiving type display element such as a liquid crystal display element can replace a CRT (cathode ray tube) which has been a mainstream of conventional display devices because of its thinness, lightness and low power consumption. It has made remarkable progress. A color filter is indispensable for colorizing this display element and obtaining a display performance closer to that of a CRT.
Various materials and methods have been proposed so far.

As a constitution of such a color filter, it is preferable that three colors of RGB are regularly arranged and black (BL) is arranged in a gap between them. RG
Examples of the pattern B include a dot matrix arrangement having a layout corresponding to display pixels, a modification thereof, or a stripe layout arranged corresponding to the shape of an electrode for applying a voltage to an electro-optical medium such as liquid crystal.

[0004]

As a method of forming a color filter portion, a printing method in which an ink in which an organic or inorganic pigment is dispersed is directly printed on a substrate is particularly practical as a simple and inexpensive method with excellent mass productivity. Has been converted. However, the printing method has a drawback in that the cross section of the ink layer becomes a mountain shape due to the force generated when the ink separates from the plate in the printing process, and it is difficult to obtain a color filter having a uniform thickness.

Further, in the printing method, there is a drawback that it is difficult to obtain the boundary linearity of the stripe filter or the shape accuracy of the dot matrix filter due to the low affinity between the substrate and the ink. Further, when a photolithography process capable of preventing these defects is used, the photoprocess needs to be repeated for each color, which causes a serious problem in mass productivity.

For the purpose of solving such a drawback, a method has been proposed in which the surface of the glass substrate is made porous or a porous layer is formed and printing is performed thereon (Japanese Patent Laid-Open No. 1-22).
48104, JP-A-1-277803). According to this, the solvent in the ink is vaporized and diffused into the porous pores, so that the viscosity of the ink is increased and the shape accuracy of printing can be improved.

However, a porous substrate having a large pore size, which allows the ink solvent to diffuse into the pores of the porous layer sufficiently quickly, has a high light-scattering property and poor transparency, and therefore is used as a color filter. When used, it has a drawback that it is difficult to obtain a clear display.

Further, when a pigment dispersion ink having high heat resistance is used as the ink, the ink layer thickness is 1.5 to 2 μm.
It is necessary to be above. However, for example, when offset printing is used, it is not possible to obtain a sufficient ink layer thickness with one printing, and it is necessary to repeat printing many times in order to obtain a sufficient ink layer thickness. In such a case, since printing is repeated many times, there is a problem that the pattern reproduction accuracy is unavoidably low.

That is, a first object of the present invention is that the solvent in the coloring material such as the pigment-dispersed ink is promptly applied after the coloring material is applied.
Since it can be diffused in the substrate, the so-called anchor effect for the coloring material is high, and the thickness of the color filter layer is uniform,
The purpose is to obtain a color filter with high boundary linearity or shape accuracy.

Another object is to achieve the first object and to obtain a color filter having high definition.

Still another object is to obtain a color filter having high pattern reproduction accuracy.

Another object of the present invention is to obtain a method for producing the above-mentioned color filter with good productivity.

Another object is to obtain a color liquid crystal display device having high sharpness.

[0014]

The present invention has been made to solve the above-mentioned problems, and includes a substrate, a porous layer formed mainly of pseudo-boehmite and provided on the substrate. The present invention provides a substrate with a color filter, which is composed of a coloring material held in a quality layer.

FIG. 1 is a sectional view showing an example of the constitution of the substrate with a color filter of the present invention. A filter layer composed of a pigment-dispersed ink portion 12 serving as a coloring material is held on a porous layer 11 composed mainly of pseudo-boehmite on a substrate 10. In the present invention, the solvent in the pigment-dispersed ink is mainly vaporized and diffused into the porous pores having a pseudo-boehmite structure. Therefore, the viscosity of the pigment-dispersed ink increases, and the ink layer adheres to the substrate relatively firmly due to the so-called anchor effect, which improves the linearity of the color filter stripes and the dot shape accuracy.

The substrate used in the present invention is not particularly limited. For example, organic sheets of polyethylene terephthalate, polyester, diacetate and the like, various glass plates and the like are exemplified. In particular, when a color filter is used for a transmissive display element, it needs to be light transmissive.

The thickness of the substrate is selected according to the purpose and is not particularly limited. When a glass substrate is used for a liquid crystal display device, a thickness of 0.3 to 1.5 mm is usually used. In order to improve the adhesion of these substrates to the porous layer provided on the surface, a surface treatment such as corona discharge treatment or a precoat layer may be provided, if necessary. Further, electrodes such as indium tin oxide (ITO), a polarizing layer, and the like can be provided in advance.

A porous layer mainly composed of pseudo-boehmite is provided on the substrate. As described above, when pseudo-boehmite is adopted as the porous alumina hydrate, the transparency of the substrate is excellent relative to the pore volume of the porous layer, and therefore, there is an advantage that a color filter having high color developability can be obtained. ..

Although this pseudo-boehmite has crystallinity, it is most preferably composed of aggregates of alumina hydrates in hairy bundles oriented in a certain direction. Due to such crystallinity of the pseudo-boehmite layer, a substrate with a porous layer having a large pore size and a large pore volume and high transparency can be obtained.

The pseudo-boehmite having such crystallinity can be obtained by applying a mixture of pseudo-boehmite alumina sol and a binder on a substrate and drying.

The binder is generally starch or a modified product thereof, PVA or a modified product thereof, SBR latex,
Organic substances such as NBR latex, hydroxycellulose and polyvinylpyrrolidone can be used, but especially in the post-process.
For display device applications requiring heat resistance of up to 200 ° C. or higher, it is desirable to use a binder which is made of an acrylic resin, an inorganic material or the like and which is resistant to discoloration upon heating and has high heat resistance.

The amount of binder used is 10 of pseudo-boehmite.
It is suitable to use about 50% by weight. When the amount of the binder used is less than the above range, the mechanical strength of the dye-supporting layer becomes insufficient, and on the contrary, when it exceeds the above range, the retention of the coloring material may be impaired. Absent.

As a method for applying the above mixture onto the substrate, various coaters such as a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater and a spin coater can be used.

In a particularly preferred embodiment of the method for producing a color filter according to the present invention, an alumina sol containing about 7% by weight in terms of Al ₂ O ₃ solid content is diluted 100 times with pure water. By using an alumina sol that forms aggregates of alumina hydrates in hairy bundles that are oriented in a certain direction when dropped on a hydrophilized collodion film and dried, it is especially useful for filters with excellent transparency. It is possible to obtain a base material.

In the present invention, when the ten-point average roughness of the surface of the porous layer is 0.05 μm or less, diffuse reflection and scattering can be further prevented and a clear filter can be obtained. Here, the ten-point average roughness is defined in JIS B0601 and was determined as follows. The three-dimensional length-measuring scanning electron microscope (ESA-3000 manufactured by Elionix Co., Ltd.) was used to observe the unevenness of the coated surface (magnification: 5000 times), and the ten-point average roughness was calculated from the obtained profile according to JIS B0601.

As a means for obtaining such a surface state, it is possible to select the material of the porous layer, but more generally, the porous layer provided on the substrate is dried by a roll or immediately before the drying. There is a method of pressing using a flat plate.

In a preferred embodiment of the present invention, the porous layer composed of pseudo-boehmite has pores having a radius of substantially 1 to 10 (nm), and the volume of the pores in the above radius range is 0.2.
Some adopt a value of ~ 1.0 (cc / g).

When such a pore distribution is adopted, it is preferable that sufficient transparency of the substrate and the anchor effect can achieve both high precision of the shape of the coloring material portion.

Further, in the present invention, in addition to this, it comprises pores having an average radius of 2 to 6 (nm), and when the average pore radius is r (nm), the radius is r-1 (nm). ~ R + 1 (n
When the pores in m) are 45% or more of the total volume ratio, it is particularly preferable because the anchor effect can be made uniform and the shape accuracy of the coloring material portion can be improved.

Generally, the control of the pore distribution is also performed by controlling the kind and amount of the binder, but if too much binder is used, the anchoring effect of the colorant may be impaired, which is not preferable and is necessary. It is preferred to choose a material that has a natural pore distribution.

When the thickness of the porous layer is 3 μm or less, preferably 1.5 μm or less, the coloring material can have leveling performance as well, so that the cross-sectional shape is preferably a relatively flat color. It becomes easier to obtain a filter layer.

In the present invention, the pore volume was measured by the nitrogen adsorption / desorption method (Omnisorb 100 manufactured by Omicron Technology).

In a preferred embodiment of the present invention, the pigment-dispersed ink is held on the porous layer as described above. The pigment may be either an organic pigment or an inorganic pigment. In particular,
In the case where there is a high temperature step of 200 ° C. or higher in a subsequent step such as when manufacturing a display body, a pigment having good heat resistance is more preferable. Examples of the pigment include anthraquinone (red), halogenated phthalocyanine (green), phthalocyanine (blue), carbon, titanium black (black), isoindolinone (yellow), dioxazine (purple), and the like. ..

These pigments are usually used by dispersing them in a vehicle made of various resins and adding an auxiliary agent for adjusting the viscosity and leveling property. The resin in the vehicle is mainly a phenol type, an alkyd type, or a polyamide type, and it is usual to use a mixture of monomers, oligomers and polymers.

As a method of holding the coloring material, it is basically preferable to adopt a printing method which is excellent in simplicity and mass productivity. Specifically, commonly used printing methods can be used, including transfer methods, etc., but offset printing is most preferable from the viewpoint of improving printing accuracy.

As described above, it is most preferable to use the printing method for the RGB pattern. However, a pigment-dispersed photosensitive resin is patterned by photolithography, black chrome or A method of patterning nickel by a physical film forming method such as electrolytic plating, chemical plating, vapor deposition, or sputtering may be used in combination. In such a case, a black mask pattern is formed on the substrate in advance by a pigment-dispersed photosensitive resin or plating, and then,
The RGB pattern may be formed by a printing method, or conversely, the black mask pattern may be formed by a pigment-dispersed photosensitive resin or plating after forming the RGB pattern by a printing method.

When the color filter thus formed is used for a display or the like, a protective layer made of an organic substance or an inorganic substance is formed thereon, and a patterned voltage is applied to a liquid crystal or other electro-optical medium. An electrode layer for forming is formed.

The protective layer is mainly made of an organic resin such as an acrylic resin, a silicone resin, a polyimide resin, an epoxy resin, or silica, alumina, titania, or a mixture thereof, and needs to be translucent. This layer has a function of protecting the color filter portion below and a function of flattening the unevenness on the surface of the color filter portion. As a result, the thickness of the electro-optical medium layer is made uniform, and a display body with good display quality can be obtained. Therefore, it is generally preferable to use an organic resin having good leveling performance as the protective layer.

Alternatively, from the viewpoint of improving the adhesion to the electrode layer provided on the protective layer, a layer formed of an inorganic material such as silica on the layer made of an organic resin is used as the protective layer. Is also preferable.

The thickness of the protective layer is preferably about 1 μm to 20 μm. If it is thinner than this, the flattening performance is insufficient, and if it is thicker than this, the transparency is lowered, or cracks or the like are generated, which causes a decrease in strength.

As a method for forming the protective layer, when the protective layer is made of an organic resin, various coaters such as a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater and a spin coater can be used. When the protective layer is made of an inorganic material, vapor deposition,
Physical film forming method such as sputtering, chemical film forming method such as CVD,
Various film forming methods such as CLD and a wet film forming method such as a spray method can be used.

Next, an electrode layer is formed on the protective layer. The electrode layer is made of aluminum, chromium or the like. Further, the transmissive display needs to be light transmissive, and it is generally preferable to use indium tin oxide (ITO) or tin oxide, but the present invention is not limited to this. Also,
The electrode layer may be patterned for display, or may be a solid electrode when used as a common electrode. The method for forming the electrode layer is not particularly limited to this, but from the viewpoint of making the layer thickness uniform,
A vapor deposition method, a sputtering method and the like are preferably used.

[0043] In the present invention, SiO ₂ above or below the electrode as required, TiO ₂ or the like of the insulating film, TFT, M
An IM, an active element such as a thin film diode, a retardation film, a polarizing film, a reflective film, a photoconductive film, or the like may be formed.

Further, in the case of a liquid crystal display, an alignment film is formed on the electrode-attached substrate, if necessary. This may be obtained by rubbing an organic resin film of polyimide, polyamide, polyvinyl alcohol or the like, obliquely vapor-deposited SiO 2 or the like, or by applying a vertical aligning agent.

Further, as a method for producing a liquid crystal display, a method which is usually used can be adopted. That is, one of the pair of substrates is the electrode substrate with the color filter, and the other is the substrate with appropriately patterned electrodes, a liquid crystal alignment film is formed on the substrate as needed, and then the pair of substrates The electrode surfaces are made to face each other and the peripheral portion is sealed to enclose the liquid crystal inside. This allows
A color liquid crystal display having high definition can be obtained.

[0046]

【Example】

Example 1 As the physical properties of the dried product (140 ° C. dried), the average pore radius was determined.
Pore volume 0.45cc / g with pores of 2.5 nm and radius 1-10 nm
10 parts by weight of solid content consisting of 10 parts (solid content) of boehmite sol (AS-2 manufactured by Catalysis Chemical Co., Ltd.), 1.5 parts (solid content) of polyvinyl alcohol PVA105 (manufactured by Kuraray Co., Ltd.) and water.
The coating solution of was prepared and dried on a transparent glass plate (thickness: 1.1 mm) by a spin coater so that the film thickness when dried was 1.5 μm, to obtain a substrate with a porous layer.

On this substrate, an RGB stripe pattern having a width of 80 μm with a black border having a width of 30 μm as a boundary was offset-printed, and each of them was printed once to form a pigment-dispersed ink layer having a thickness of 2 μm. As pigment dispersion ink,
An anthraquinone-based (red), halogenated phthalocyanine-based (green), or phthalocyanine-based (blue) pigment dispersed in an aminoalkyd-based resin was used.

On this ink layer, a transparent silicone resin was applied by a spin coater so that the thickness after curing was 3 μm,
It was heated and cured to form a film.

The maximum boundary linearity of printing was 5 μm or less in absolute value, and extremely good linearity was obtained.

Example 2 As the pore properties of the dried product (drying at 140 ° C.), the average pore radius was
Solid content consisting of 10 parts (solid content) of boehmite sol having a pore volume of 0.70 cc / g and having a pore size of 6 nm and a radius of 1 to 10 nm, polyvinyl alcohol PVA117H (manufactured by Kuraray Co., Ltd.) and 1.5 parts (solid content) and water. A coating liquid of 10% by weight was prepared and dried on a transparent glass plate (thickness: 1.1 mm) by a spin coater so that the film thickness when dried was 0.5 μm to obtain a substrate with a porous layer.

Example 1 was applied to this substrate to form an RGB stripe pattern having a width of 80 μm with a black having a width of 30 μm as a boundary.
Offset printing was performed using the same ink as in Example 1 and printing was performed once for each to form a pigment-dispersed ink layer having a thickness of 2 μm.

A transparent silicone resin was applied onto the ink layer by a spin coater so that the thickness after curing was 2 μm,
It was heated and cured to form a film.

The boundary linearity of the printing was 5 μm or less in maximum in absolute value, and extremely good linearity was obtained.

Example 3 10 parts by weight (solid content) of the boehmite sol used in Example 2, 1.5 parts (solid content) of polyvinyl alcohol PVA117H (manufactured by Kuraray Co., Ltd.) and about 10% by weight of solid content of the coating liquid were added. It was adjusted and dried on a transparent glass plate (thickness: 1.1 mm) by a spin coater so that the film thickness when dried was 1.0 μm, to obtain a substrate with a porous layer.

This substrate was subjected to a stripe pattern of RGB having a width of 70 μm with a black border having a width of 30 μm as a boundary in Example 1.
Offset printing was performed using the same ink as in (1), and printing was performed once for each to form a pigment-dispersed ink layer having a thickness of 1.5 μm.

A transparent silicone resin was applied onto the ink layer by a spin coater so that the thickness after curing was 3 μm,
It was heated and cured to form a film.

The boundary linearity of printing was 5 μm or less in maximum in absolute value, and extremely good linearity was obtained.

Example 4 Using the color filters of Examples 1 to 3 as one of the substrates, a transparent conductive film made of patterned ITO and an alignment film obtained by rubbing a polyimide film were formed on the substrate. Liquid crystal Z containing a chiral compound
Using LI2293, a 240 ° twisted 1/240 duty liquid crystal display element was prepared as shown in the sectional view of FIG. In the figure, 21 and 22 are substrates, and 23 and 2
4 is an ITO layer, 25 is a sealing material, 26 is a liquid crystal layer, 27 is a color filter layer with a protective film of Examples 1 to 3, and 28 is an alignment film. When this liquid crystal display device was driven, a clear color display was obtained.

[0059]

According to the present invention, the solvent in the coloring material such as the pigment-dispersed ink can be vaporized and diffused into the substrate immediately after coating, so that the so-called anchor effect for the ink is high and the thickness of the color filter layer is high. It is possible to obtain a substrate with a color filter which is uniform in color and has high boundary linearity or shape accuracy of the color filter. The absolute value of the printed edge linearity is 5 μm or less in absolute value, which is extremely high accuracy compared with the conventional example.

At the same time, since the printing substrate has high transparency, it is possible to obtain a substrate with a color filter having high definition.

Further, since the ink layer can be formed only by printing once by offset printing, it is possible to obtain a substrate with a color filter having high pattern reproduction accuracy.

Furthermore, since the printing can be performed once, it is possible to obtain a method for producing a substrate with a color filter with high productivity.

Furthermore, a color liquid crystal display having a high definition can be obtained by using the above-mentioned substrate with a color filter.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the configuration of a substrate with a color filter of the present invention.

FIG. 2 is a sectional view showing a liquid crystal display body using the substrate with a color filter of the present invention.

[Explanation of symbols]

 10 Substrate 11 Porous Layer 12 Pigment Dispersion Ink Part 21, 22 Substrate 23, 24 ITO Layer 25 Sealing Material 26 Liquid Crystal Layer 27 Protective Color Filter Layer 28 Alignment Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaya Toyonaga 1150, Hazawa-machi, Kanagawa-ku, Kanagawa Prefecture Central Research Institute of Asahi Glass Co., Ltd. (72) Kenji Matsuhiro 1150, Hazawa-machi, Kanagawa-ku, Yokohama Asahi Glass Co., Ltd. Company Central Research Institute

Claims (5)

[Claims] 1. A substrate with a color filter comprising a substrate, a porous layer formed on the substrate, which is mainly composed of pseudo-boehmite, and a coloring material retained on the porous layer. 2. The porous layer made of pseudo-boehmite has pores having a radius of substantially 1 to 10 (nm), and the volume of pores in the above radius range is 0.2 to 1.0 (cc / g). ) The substrate with a color filter according to claim 1. 3. The porous layer made of pseudo-boehmite is composed of pores having an average radius of 2 to 6 (nm), and when the average pore radius is r (nm), the radius is r-1 (nm). ) ~ R + 1 (nm)
The substrate with a color filter according to claim 1 or 2, wherein the pores in (1) are 45% or more of the total volume ratio. 4. A step of applying a mixture of pseudo-boehmite alumina sol and a binder on a substrate and drying the mixture to form a porous layer on the substrate, and a step of holding a coloring material on the porous layer. A method of manufacturing a substrate with a color filter, comprising: 5. A liquid crystal display having a liquid crystal layer sandwiched between a pair of substrates with electrodes, wherein at least one of the substrates is a coloring material for a substrate with a color filter according to any one of claims 1 to 3. Alternatively, a liquid crystal display body using a substrate with an electrode having an electrode layer provided below.