JPH07318717A - Substrate with color filter and liquid crystal display element using that - Google Patents

Abstract

PURPOSE:To obtain a substrate which is inexpensive and of high quality and has enough absorbance without blotting or the like by forming a color layer colored with a coloring agent and comprising pseudo-boehmite particles and a binder resin on a substrate. CONSTITUTION:A light-shielding layer 2 is formed as required on a substrate 1, and then a colored layer 3 and a sealing layer 4 are formed. Further, as required, a protective layer 5 and an electrode layer 6 are formed. The colored layer 3 consists of a holding layer for a coloring agent and a coloring agent held in the holding layer. The holding layer for the coloring agent is a mixture of a binder resin and pseudo-boehmite particles, namely, alumina hydrate having a pseudo-boehmite structure. The holding layer for the coloring agent has enough pores to absorb ink so that the film has same smoothness even after colored as the film before colored. The shape of pseudo-boehmite particles determines the pore shape and pore volume of the porous film which is the holding layer for the coloring agent. The whole volume of pores in the porous film is 0.7-1.2cc/g.

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 and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art In recent years, a color filter has attracted attention as a device for enabling color display of a liquid crystal display device. This is generally a colored layer of three primary colors of red, blue and green formed on a transparent substrate such as glass in a specific pattern such as a stripe pattern.

Conventionally, various methods such as an electrodeposition method, a photolithography method and a printing method have been used as a method for forming the colored layer. However, these methods require a washing step after forming each color in addition to the colored layer forming step, and the number of steps is large. In addition, a complicated line and a large-sized device are required, which causes a decrease in yield and an increase in cost.

[0004]

As another method of forming a colored layer, a method of using an inorganic porous film as an ink receiving layer has been proposed (see JP-A 61-69004, JP-A 1-271704, etc.). ). This is Al ₂ O ₃
And the like, or the organic mordant is filled in the porous film and then the mordant is colored.

However, according to this method, in order to form an inorganic porous film layer having an appropriate thickness, it is necessary to coat the substrate with the alumina sol and then bake at a high temperature of 400 ° C. or higher. Therefore, plastic substrates cannot be used.
Further, even if a glass substrate is used, the warpage of the substrate is likely to occur during firing. When such a substrate is used for a liquid crystal display element, it is difficult to control the substrate gap, which causes deterioration of display quality.

An example of a color filter that can be produced at a low temperature is described in JP-A-3-116002. In this example, an ink receiving layer made of a mixture of pseudoboehmite and a binder resin is used. It is difficult to form a film of pseudo-boehmite by itself, but in this example, the film formation is facilitated by mixing a binder resin. In particular, it is sufficient that the firing is unnecessary or that the firing is performed at a low temperature during the film formation. Therefore, it is promising as a color filter for a plastic liquid crystal display which is currently being developed for the purpose of weight reduction. Further, in general, many dyes are likely to be negatively charged, whereas pseudo-boehmite is likely to be positively charged. For this reason, the dye adsorption capability of pseudo-boehmite is very high due to the electrostatic force between them.

As described above, the porous film described in JP-A-3-116002 is promising as an ink receiving layer of a color filter, but as the inventors proceeded with research, it was insufficient in the following points. It was found that there is.

When colorizing a liquid crystal display device with color filters of three primary colors, it is desirable that the transmittance at the maximum absorption wavelength of each color is 30% or less, preferably 20% or less. In order to achieve such a transmission, a large amount of dye needs to be absorbed in the receiving layer.

In the porous film described in JP-A-3-116002, the absorptivity is insufficient in view of the above points, the required amount of ink cannot be completely absorbed at the time of printing, and the dye aggregates on the surface of the porous film to cause color filter. In some cases, such a phenomenon that the flatness as described above cannot be ensured or the dye flows out to other pixels to cause color mixing, bleeding, or the like.

In addition, the physical characteristics of the ink greatly change depending on the type of dye and various solvents used for forming the ink. In the porous membrane described in JP-A-3-116002, since the amount of pores in the porous membrane cannot be controlled sufficiently, the state of absorption into the porous membrane differs depending on the type of ink. Therefore, the print form, that is, the protrusion, the print line width, and the like, greatly changes. For this reason, the ink that can obtain an appropriate printed material is limited, which hinders development.

The present invention has been made to solve the above-mentioned problems, and a clear color image having a sufficient color density of a color pattern, no bleeding, and no aggregation of dye on the surface of the absorbing layer is obtained. An object of the present invention is to provide a substrate with a color filter as described above.

[0012]

DISCLOSURE OF THE INVENTION The present invention provides a light-shielding layer on a substrate, a porous colored layer which is colored with a colorant and is composed of pseudo-boehmite particles and a binder resin, and a sealing layer which seals the colored layer. , And a substrate with a color filter having an electrode layer, particularly, the total volume of pores contained in the colored layer formed by pseudo-boehmite particles is 0.7 to
There is provided the above-mentioned substrate with a color filter, wherein the substrate has a color filter of 1.2 cc / g.

Since the color filter of the present invention has the coloring layer which is provided on the substrate and is colored with the coloring agent and which is composed of the pseudo-boehmite particles and the binder resin,
The ink receiving amount can be increased, and there is no bleeding, ink color mixing, and protrusions, and a good printed material can be obtained. The use of an anionic dye as the ink is particularly effective because the ink is held by the electrostatic force between the ink and the pseudo-boehmite. As described above, sufficient absorbance can be obtained even when the thickness of the ink receiving layer is thin, so that a color filter having high light transmittance can be obtained. In addition, the amount and size of the pores of the colored layer can be appropriately adjusted according to the physical properties such as the viscosity of the ink to be printed to form a porous film that easily absorbs the ink.

An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing the outline of a substrate with a color filter of the present invention. After providing the light shielding layer 2 on the substrate 1 as needed, the colored layer 3 and the sealing layer 4 are provided. Further, an electrode layer 6 is provided via a protective layer 5 if necessary.

As the material of the substrate 1, glass, quartz, plastic or the like can be used. Examples of the plastic material include polyethylene terephthalate, polyether sulfide, acrylic, polycarbonate, polyimide and the like. Of course, it is not limited to these as long as they do not interfere with the characteristics of the color filter.

In particular, when manufacturing the substrate with a color filter of the present invention, a step of baking at a high temperature is substantially unnecessary, so that a plastic material can be adopted. When a plastic material is used, it is preferable that the surface is hard-coated before use. When using ordinary soda lime glass, it is preferable to previously form a film such as SiO ₂ as an alkali barrier by a method such as CVD.

The light-shielding layer (black matrix) 2 is provided to ensure the color separation of the colors of the color filter, and may not be provided depending on the required degree of color separation. Normally, it is provided below the colored layer 3, but it may be provided above the colored layer.

As the material, a single layer of an inorganic material such as metallic chromium or chromium oxide, or a multilayered combination thereof, a dye-receiving layer such as gelatin dyed with a dye, or an organic resin mixed with a pigment Etc. can be used.
Print these materials on the substrate in a predetermined pattern,
A film is formed on the entire surface of the substrate by a method such as electrolytic plating, chemical plating, vapor deposition, and sputtering, and then patterned by photolithography to form a film having a predetermined shape. As the pattern, a stripe pattern or a matrix pattern may be appropriately adopted depending on the application.

The coloring layer 3 comprises a coloring agent holding layer and a coloring agent held in the coloring agent holding layer. Here, the colorant retaining layer is a mixture of coagulated boehmite particles, that is, alumina hydrate having a pseudo-boehmite structure and a binder resin. The colorant retaining layer has sufficient pores to absorb the ink.
As a result, the same smoothness as before coloring can be maintained after coloring.

The coagulated boehmite particles preferably have a particle size distribution so that they can be easily dispersed as a sol in the dispersion medium in order to improve the coatability on the substrate. Water can usually be used as the dispersion medium.

As a raw material for the pseudo-boehmite particles, those having a small amount of cationic impurities such as sodium are preferable from the viewpoint of enhancing the reliability of the liquid crystal. For example, aluminum alkoxide is suitable. In this case, as the alkoxide used in the reaction, aluminum triisopropoxide, aluminum trisec-butoxide and the like can be used, and the use of aluminum isopropoxide is particularly preferable. This is because the reactivity is appropriate and it is easy to handle, and the by-product at the time of hydrolysis is isopropanol, which is an azeotropic mixture with water, so that it can be easily removed.

Any binder resin can be used as long as it is soluble in the dispersion medium. For example, when water is used as the dispersion medium, water-soluble resins such as melamine resin, polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetal, hydroxycellulose-based resin, starch and its modified products, SBR latex, NBR latex are used. Available.

Colorant (ink) retained in the colorant retaining layer
As the dye, a dye having a good absorbability is suitable. Particularly preferred are water-soluble dyes, and more preferred are acid dyes that electrostatically associate with cationically charged pseudoboehmite.
As the dye structure, known structures such as azo type, phthalocyanine type and anthraquinone type can be appropriately used, and in some cases, a complex having a metal ion at the center may be used. A sulfonic acid group, an amino group, a carboxyl group or the like can be used as the functional group imparting anionicity. The presence of cation ions such as sodium in the dye may elute the cation ions into the liquid crystal layer, so these ions are preferably removed by a method such as salting out or ion exchange.

As a method for absorbing the ink in the colorant holding layer, it is very preferable to use a non-impact printer, especially an ink jet printer. In addition to this, known dyeing methods and various printing methods such as screen printing and offset printing. Can be used. When the inkjet printing method is used, a method of arranging three or more ink nozzles in parallel and forming three colors at the same time is most preferable in terms of mass productivity.

The shape of the pseudo-boehmite particles determines the pore shape and the pore volume in the porous film which is the colorant retaining layer. In the present invention, the total volume of pores contained in the porous membrane is 0.7 cc / g or more. If the total volume of pores is less than 0.7 cc / g, the ink required for the color filter cannot be absorbed, and there is a possibility that the ink will rise on the surface of the porous film. When the ink rises on the surface of the porous film,
When the sealing layer is provided in a later step, the formation may not be performed uniformly, which may cause waviness and cracks. Further, since the dye that has not been absorbed in the porous film is solidified and crystallized, the original transparency of the dye may be impaired.

Further, it is 1.2 cc / g or less, preferably 1.0 cc / g or less. With respect to those having a pore volume exceeding 1.2 cc / g, since the pore volume of each is large, the ink spreads quickly and bleeding easily occurs.
Therefore, the color density required for the color filter cannot be achieved. In addition, if the pore volume is large, it may be difficult to apply a protective film in a subsequent step.

Regarding the pore distribution, of the total pore volume,
0.1cc / having a pore radius of 10 to 100nm
It is preferably at least g. This is because such pores have excellent ink absorbency and are less likely to cause bleeding. From this viewpoint, those having a pore radius of 10 to 100 nm are most preferably 0.5 cc / g or less.

In the pseudo-boehmite particles used in the present invention,
By deflocculating the gel after the reaction, the final product of hydrolysis can have an appropriate pore distribution.

Peptizers used for peptization include nitric acid,
Monovalent acids such as perchloric acid, hydrochloric acid, acetic acid, butyric acid, and salts thereof can be used. Since the degree of peptization is appropriate,
Acetic acid and ammonium acetate are particularly preferable. Peptization is performed more efficiently as the amount of acid used increases. Therefore, by controlling the amount of acid and controlling the peptization rate, it becomes possible to synthesize the one having the best dye absorbability.

The amount of ink absorbed by the porous film can be changed by changing the resin forming the porous film and the solvent used for coating. Specifically, the ink absorbability of the resin, the affinity with pseudo-boehmite, the drying property of the solvent, and the like may be controlled.

The mixing ratio of the pseudo-boehmite particles and the binder resin is 3 parts by weight or more, preferably 5 parts by weight or more with respect to 100 parts by weight of the coagulated boehmite particles. When the resin content is less than 3 parts by weight, the strength of the film tends to be low. Further, it is 30 parts by weight or less, preferably 20 parts by weight or less, with respect to 100 parts by weight of coagulated boehmite. If the resin content is more than 30 parts by weight, the pore volume after film formation tends to be small, and the ink holding amount tends to be small.

The coating thickness is 0.1 μm or more, preferably 0.5 μm or more. If it is thinner than this, there is a tendency that a sufficient amount of pores for holding the ink cannot be obtained. Further, it is 30 μm or less, preferably 4.0 μm or less. If it is thicker than this, cracks are likely to occur and the translucency tends to deteriorate.

As a method of applying the sol for forming the colorant-holding layer, an ordinary method of applying a paint can be adopted. That is,
After coagulating boehmite particles and a binder resin by an appropriate method and adjusting a coating solution using water as a solvent, a blade coating method, an air knife coating method, a bar coating method, a spin coating method, a spray method, a roll coating method, etc. It can be applied using a known method for forming a thin film. A water-soluble organic solvent such as an alcohol solvent such as methanol, a nonpolar solvent such as acetone, or a polar solvent such as N-methylpyrrolidone can be appropriately added to the coating liquid. If necessary, a water-soluble plasticizer such as glycerin, a surfactant, a dispersant,
Stabilizers, gelling agents, etc. can be added.

In order to improve the adhesiveness with the substrate 1 before coating, as long as the characteristics of the color filter are not impaired,
The transparent substrate may be subjected to a chemical treatment with a coupling agent or the like, or a physical treatment for activating the substrate surface using sputtering or the like.

The sealing layer 4 is used for filling the pores of the colorant retaining layer, which is a porous layer, and strengthening the retaining layer, immobilizing the colorant in the retaining layer and transmitting light. This is for improving the property. Further, it also has an effect of preventing the migration of impurities to the liquid crystal side.

Specifically, transparent organic resins such as acrylic, epoxy, polyamide, polyimide, silicone and urethane, titanium oxide, zirconium oxide, tin oxide, silica,
An inorganic material such as an oxide or a nitride having a light-transmitting property such as alumina or silicon nitride can be used, but the material is not limited thereto as long as it satisfies the characteristics required for the above coating.

A coating solution is prepared by dissolving these substances or precursors for forming these substances in an organic solvent, and the coating liquid is applied onto the dye-retaining layer by an appropriate method and, if necessary, a curing reaction is carried out. As the precursor which can be used in the coating liquid, various photocurable monomers and oligomers, organic precursors such as thermosetting monomers and oligomers, inorganic precursors such as metal alkoxides, organometallic compounds, cyanate compounds, etc. can be used as necessary. Can be used.

As the organic solvent that can be used, acetone,
Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, aromatic solvents such as benzene, toluene and xylene, halogen solvents such as 1,1,1-trichloroethane and trichloroethylene, CFC solvents such as R-225 and R-1416. , Alcoholic solvents such as methanol and ethanol can be used alone or in any mixing ratio.
Further, if necessary, a light stabilizer, a defoaming agent, an antioxidant, a leveling agent, a surfactant, a catalyst and the like can be introduced. In addition,
The viscosity of the coating liquid is preferably 200 cP or less because the coating liquid needs to penetrate sufficiently without destroying the dye holding layer.

The protective layer 5 is provided on the boundary between the uppermost transparent electrode of the color filter and the liquid crystal layer, and has a role of protecting the color filter and providing a stable screen. Specifically, it has almost the same composition as the sealing layer, but requires a certain degree of high hardness in order to prevent compression from the outside in the subsequent process such as liquid crystal injection and to keep the color filter flat.

The coating thickness, including the sealing layer, is preferably less than 20 μm after curing, particularly preferably 2 μm or less. When it is thick, cracks and waviness are likely to occur, which may adversely affect the refractive index and the like.

As a method for forming the protective layer 5,
In addition to the same method as that for the colorant holding layer, a sputtering method or a CVD method can be adopted.

The protective layer 5 may not be provided if the color filter provided with the sealing layer 4 is sufficiently smooth and has strength.

In addition, as a characteristic common to the colorant, the colorant-holding layer, the pore-sealing layer and the protective layer, a post-process, particularly ITO.
Heat resistance is required so that the physical properties do not change during film formation, that is, the color does not change at a temperature of about 200 ° C. Further, in order to enhance the reliability of the liquid crystal, it is preferable that the amount of cationic impurities such as sodium is small.

When used as a liquid crystal display cell, an electrode layer 6 is formed on the protective layer 5. 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), tin oxide, or the like.
It is not limited to this. The electrode layer 6 may be patterned for display, or may be a solid electrode when used as a common electrode. The method of forming the electrode layer 6 is not particularly limited to this, but from the viewpoint of making the layer thickness uniform, a vapor deposition method, a sputtering method, or the like is preferably used.

[0046] In the present invention, SiO ₂ above or below the substrate electrode if necessary, TiO ₂ or the like of the insulating film, T
Active elements such as FT, MIM, and thin film diode, a retardation film, a polarizing film, a reflective film, a photoconductive film, and 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, may be obliquely vapor-deposited of SiO, or may be used by applying a vertical alignment agent.

Further, as a method of manufacturing a liquid crystal display element, a method which is usually used can be adopted. This will be described with reference to FIG. That is, one of the pair of substrates is the substrate 1a with the color filter layer 10 and the other is the substrate 1b with the appropriately patterned electrode layer 6b, and a liquid crystal alignment film is formed on the substrate as needed. Then, the pair of substrates are opposed to each other with their electrode surfaces facing each other, and the peripheral portions thereof are sealed with a sealing material 7 to enclose the liquid crystal therein.
As a result, a color liquid crystal display having high definition can be obtained.

From the viewpoint of application, the substrate with a color filter of the present invention includes a liquid crystal display surface, a cathode ray tube display surface, a light receiving surface of an image pickup tube, and the like. Further, since a color filter having extremely small thickness unevenness can be obtained, it is particularly preferable for a liquid crystal element in which the accuracy of the substrate spacing is strict.

[0050]

EXAMPLE Chromium was sputtered on the entire surface of a glass substrate, a black mask pattern was formed by photolithography, and etching was performed.

Next, a pseudo-boehmite sol was synthesized.
204.25 g of aluminum triisopropoxide,
751 g of isopropanol and 900 g of water are mixed,
It was hydrolyzed in a 2000 cc glass reactor for 24 hours, deflocculated using various deflocculants as shown in Table 1, and concentrated to obtain white sol liquids. When this sol solution was dried and the pore distribution and pore volume were measured by the nitrogen adsorption method, the distribution was as shown in FIG.

50 parts by weight of the pseudo-boehmite sol and "ESREC K" (manufactured by Sekisui Chemical Co., Ltd.) as a water-soluble binder are mixed and applied by spin coating to the above-mentioned substrate on which a black mask has been prepared, and 150 ° C. And was fixed for 30 minutes by heating to form an ink receiving layer.

Next, when the size of the ink droplet ejected from the ink jet printer was measured by stroboscopic photography, the diameter was about 50 μm.

Next, an ink jet ink was prepared. The concentration of RGB dye in the ink is 9%,
The mixed solvent as shown in Table 2 was used.

This ink was used to form an RGB stripe pattern on an ink receiving layer using the sol shown in Table 1 by an ink jet printer, and dried in an oven at 50 ° C. for 1 hour to thoroughly dry the ink solvent, and then the optical The RGB stripe pattern was measured using a microscope, and the unevenness on the line was measured using a stylus type surface roughness meter. The measurement results are shown in Table 3.

In the sol of Examples 1 and 2, the ink was not sufficiently absorbed by the ink receiving layer, and projections were generated on the surface.
On the other hand, in the sol of Example 7, ink bleeding occurred and the required color density was not obtained. Especially because the blurring is severe,
There was also a phenomenon in which, when different colors were printed, color mixing occurred partially at the line ends. With the sols of Examples 3 to 6, good printed surfaces with smooth surfaces were obtained.

Next, the main component: "Epicoat 1001" (trade name: Epoxy Shell epoxy) 65 parts by weight, the curing agent: phthalic anhydride 35 parts by weight, the solvent: toluene, xylene, 1
A coating solution having a composition of 30 parts by weight of a mixture of -methoxy-2-propanol was prepared, applied onto the substrate by spin coating, heated at 150 ° C for 1 hour, and cured to form a sealing layer.

Further, 95 parts by weight of pentaerythritol triacrylate, 5 parts by weight of 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photopolymerization initiator, and a mixture of isobutanol and hexylene glycol as a solvent. A coating solution having a composition of 30 parts by weight was prepared, applied onto the substrate by spin coating, UV-cured, and then cured at 150 ° C. to form a protective layer.

The substrate with a color filter prepared by this method is incorporated into a liquid crystal module as a substrate, and the temperature is set to 90.
When left for 1000 hours at 80 ° C and 80% humidity,
No disconnection or change in the specific resistance of the liquid crystal occurred.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

With the substrate with a color filter of the present invention, a three-color simultaneous formation is possible, and a low-cost and highly reliable color filter that can be manufactured using a relatively small-scale apparatus can be obtained. In particular, by setting the total pore volume of the colorant-holding layer within a specific range, it is possible to obtain an inexpensive and high-quality substrate with a color filter that has sufficient absorbance and does not cause bleeding.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a substrate with a color filter of the present invention.

FIG. 2 is a schematic sectional view showing a liquid crystal display element of the present invention.

FIG. 3 is a graph showing the relationship between pore radius and pore size distribution.

[Explanation of symbols]

 1: Substrate 2: Light-shielding layer 3: Colored layer 4: Sealing layer 5: Protective layer 6: Electrode layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nying Nonaka 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory

Claims (6)

[Claims] 1. A substrate having a light-shielding layer, a porous coloring layer, which is colored with a coloring agent, and is composed of pseudo-boehmite particles and a binder resin, a sealing layer for sealing the coloring layer, and an electrode layer, which are arranged on the substrate in this order. Characteristic substrate with color filter. 2. The total pore volume before coloring contained in the coloring layer formed of pseudo-boehmite particles is 0.7 to 1.2 cc /.
The substrate with a color filter according to claim 1, wherein g is g. 3. Among the pores before coloring contained in the colored layer formed by the pseudo-boehmite particles, those having a pore radius of 10 to 100 nm are 0.1 cc / g or more. The substrate with a color filter according to claim 2. 4. The coloring agent in the coloring layer is a water-soluble dye, and the coloring layer is any one of claims 1 to 3.
A substrate with a color filter according to the item. 5. A non-impact printer is used as a means for coloring the colored layer.
~ The substrate with a color filter according to claim 4. 6. A liquid crystal display device using the substrate with a color filter according to any one of claims 1 to 5 as at least one substrate.