JPH07301708A - Substrate with color filter, its production and liquid crystal display element using the same - Google Patents

Abstract

PURPOSE:To provide an inexpensive color filter having high reliability. CONSTITUTION:A porous layer essentially comprising inorg. particles and a binder resin is formed on a substrate and colored to form a specified pattern. In this substrate having the color filter, the binder resin in the porous layer essentially consists of at least one kind of resin selected from polyvinylacetal, amino resin, acryl resin and modified resin of them. Thereby, the obtd. filter has good adhesion property and heat resistance so that it is suitable for a liquid crystal display element.

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 more particularly to a substrate with a color filter having excellent heat resistance and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a color filter has attracted attention as a device capable of color display of a liquid crystal display device. This is one in which colored layers of three primary colors of red, blue and green are 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 this colored layer. However, these methods are complicated because they require a washing step after pattern formation for each color in addition to the colored layer forming step. Further, since such a large number of steps are performed, the yield of products is lowered, and complicated lines and large-sized equipment are required for manufacturing, which also increases manufacturing cost.

On the other hand, as another method for forming a colored layer, a method of using an inorganic porous film as an ink receiving layer has been proposed (JP-A-62-69004, JP-A-1).
-271704 publication). In this method, the inorganic porous membrane layer such as Al ₂ O ₃ is directly colored, or an organic mordant is filled in the porous membrane and then the mordant is colored.
However, the colored layer obtained by this method is fragile and has a drawback that it is easily removed due to the bending of the substrate.

The above-mentioned drawbacks have been ameliorated by forming the colored layer of the color filter with a porous layer composed of porous inorganic particles and a binder resin (JP-A-3-11).
No. 6002). In this case, the color filter
For example, a porous layer made of a mixture of pseudo-boehmite sol and a water-soluble resin can be used as the ink receiving layer. Typical examples of the water-soluble resin are polyvinyl alcohol, polyvinylpyrrolidone, hydroxycellulose, S
Examples include BR latex and NBR latex.

Unlike such a porous film made of only an inorganic material, such a film can be formed at a low temperature, so that the process is simple, and the dimensional stability caused by the film formation at a high temperature is improved. There is also an advantage that the decrease can be avoided. It is also promising as a color filter for plastic liquid crystal displays, which is currently being developed for the purpose of weight reduction.

[0006]

As described above, Japanese Unexamined Patent Application Publication No.
The porous layer described in JP-A-111002 is promising as an ink receiving layer of a color filter. However, it has been found that there is a drawback that the water resistance and the heat resistance required at the time of manufacturing a color filter for liquid crystal are insufficient. That is, it is a defect that the porous layer is easily peeled off under high humidity and the color is easily changed under high temperature.
These drawbacks make it difficult to incorporate a color filter into a liquid crystal display device and reduce display stability.

Therefore, a first object of the present invention is to provide a substrate with a color filter having a colored layer which is excellent in resolution and transparency and which is difficult to peel off even under high humidity. A second object of the present invention is to provide a substrate with a color filter having heat resistance suitable for a color filter for liquid crystal. A third object of the present invention is to provide a method for producing a substrate with a color filter, which is suitable for a high-performance color filter for liquid crystal. Further, a fourth object of the present invention is to provide a liquid crystal display device having high accuracy and excellent durability.

[0008]

The above-mentioned various objects of the present invention include a color obtained by providing a porous layer composed mainly of inorganic particles and a binder resin on a substrate and coloring it to form a specific pattern. In the substrate with a filter, the binder resin contained in the porous layer is mainly composed of at least one selected from the group consisting of polyvinyl acetal, amino resin, acrylic resin and modified products thereof. And a method of manufacturing the same, and a liquid crystal display device using the same.

The substrate used in the present invention can be appropriately selected from known substrates such as polymeric materials such as polyester films and polyimide films, glass plates and the like.
The inorganic particles used in the present invention can be appropriately selected from known inorganic oxide particles having excellent transparency such as alumina and silica, but usually, since an acid dye is used as a coloring agent, its dyeing It is preferable to use an alumina hydrate having a pseudo-boehmite structure which is excellent in adhesion.

From the viewpoint of improving the printability in printing a specific pattern for forming a color filter, the particle size of the inorganic particles is preferably about 2 μm or less, and particularly preferably 1 μm or less. Preference is given to using. In the present invention, it is necessary to apply a coating liquid containing the above-mentioned inorganic particles and a binder resin on a substrate to provide a porous layer that is uniform and has excellent printability. Must have good dispersibility in the binder resin.

From this point of view, a water-soluble binder resin or a monomer or oligomer is used instead of a non-water-soluble binder resin which requires a large amount of various stirrers such as a dispersant and a homogenizer, and is used as an aqueous coating solution. Preferably. The binder resin used in the porous layer in the present invention is a polyvinyl acetal resin, instead of the conventionally used polyvinyl alcohol or the like.
It is selected from the group consisting of amino resins, acrylic resins, and modified products thereof. These binder resins may be used alone or in combination of two or more.

The polyvinyl acetal used in the present invention is preferably represented by the following chemical formula 2.

[Chemical 2] However, R in Formula 2 is C _n H _{2n + 1,} the average value of n is preferably from 0.3 to 4.5.

The polyvinyl acetal can be easily obtained by adding various aldehydes to polyvinyl alcohol and condensing it by a known method.
The degree of polymerization of polyvinyl alcohol used in this case is 3
It is preferably from 00 to 5,000, and particularly from 700 to
It is preferably 3,000. If the degree of polymerization is less than 300, the strength of the porous layer will be insufficient, and if it exceeds 5,000, the water solubility will be poor, and the coating property will deteriorate due to an increase in the viscosity of the coating solution, which is not preferable.

The aldehyde can be appropriately selected and used from general-purpose aldehydes such as formaldehyde, acetaldehyde, propanal and butanal. Degree of acetalization of polyvinyl acetal is 3%
-25% is preferable, and 5-10% is particularly preferable. If the degree of acetalization is less than 3%, the water resistance is poor, and if it exceeds 25%, the water solubility is poor.

If the average value of n in the above chemical formula 2 is smaller than 0.3, the water resistance is poor, and if it is larger than 4.5, the water solubility is poor. Preferred polyvinyl acetals as described above are
By heating at 50 ° C. to 150 ° C., preferably 80 ° C. to 130 ° C. during drying, moisture is sufficiently released to firmly adhere to the transparent substrate and a coating film having high water resistance can be formed.

The amino resin can be made into a resin having high water resistance and high dye solubility by coating a corresponding water-soluble manomer or oligomer and condensing it. Melamine resin is particularly preferable because it has high heat resistance. Drying after coating is performed at 80 ° C to 200 ° C, especially 1
It is preferably carried out at 00 ° C to 150 ° C. By this drying, condensation proceeds and a resin having excellent water resistance and heat resistance is obtained.

As the acrylic resin, it is particularly preferable to use a water-soluble monomer or oligomer after photocuring. Examples of such water-soluble monomers include monoacrylates such as hydroxymethacrylate and acrylic acid, and diacrylates such as tetraethylene glycol diacrylate and triethylene glycol diacrylate. In the present invention, these monomers or oligomers may be mixed alone or in an arbitrary ratio, and a suitable curing agent may be mixed with the above-mentioned inorganic substance, if necessary, and then photocured.

From the viewpoint of heat resistance, the degree of polymerization of the amino resin and the acrylic resin after film formation is preferably 100 to 2,000. In addition, as the functional groups introduced into the binder resin, a hydroxyl group, a carboxyl group, a sulfone group, etc. for increasing hydrophilicity; an amino group, etc. for increasing the adsorptivity of the dye, and a nitro group, etc. for increasing heat resistance It can be introduced as needed. Further, in order to improve the film-forming property, a plasticizer such as glycerin as an auxiliary agent and a leveling agent at the time of application (in the range of about 10% by weight or less with respect to the binder resin) may be added, if necessary. . Further, when the emulsified dispersion liquid is used as the coating liquid, the nonionic surfactant may be used in a range of about 3% by weight or less.

The mixing ratio of the inorganic particles and the binder resin is 1 part by weight of the binder resin with respect to 100 parts by weight of the inorganic particles.
It is preferably from 30 to 30 parts by weight, and particularly preferably from 5 to 10 parts by weight. If the resin content is less than 1 part by weight, the strength of the film tends to be low, and if the resin content is more than 30 parts by weight, the pore volume after film formation tends to be small and the dye retention amount tends to be small. .

The thickness of the porous layer is 0.1 μm to 30 μm.
Is preferable, and particularly 0.5 μm to 4.0 μm
Is preferred. If it is thinner than 0.1 μm, the amount of pores enough to hold the dye cannot be obtained, and if it is thicker than 30 μm, cracks are likely to occur. In the present invention, inorganic particles and an organic compound such as a binder resin are mixed by a suitable method to prepare a water-soluble liquid, and a blade coating method, an air knife coating method, a spin coating method, a spray method, a roll method. The porous layer can be provided by coating on a transparent substrate using a known thin film forming method such as a coating method.

In this case, a water-soluble organic solvent such as an alcohol solvent such as methanol, a nonpolar solvent such as acetone, a polar solvent such as N-methylpyrrolidone or the like is appropriately added to the coating liquid within a range not impairing the dispersibility. can do. Also,
As described above, if necessary, a water-soluble plasticizer such as glycerin, a surfactant, a dispersant, a stabilizer, a gelling agent, etc. can be added. The viscosity of the coating liquid is 300 cp or less, more preferably 100 c, from the viewpoint of improving the flatness during coating.
p or less. The viscosity can be adjusted by appropriately adding a solvent.

Dyeing of the porous layer is carried out by the conventional printing method,
It can also be performed using a non-impact printer such as an inkjet printer. The porous layer has pores sufficient to absorb the ink in which the dye is dissolved, and no phenomenon in which the dye deposits on the colored layer is observed even after the ink is absorbed to form the colored layer. The same smoothness as before coloring can be maintained.

In order to evaluate the heat resistance of the colored layer that has absorbed the ink, it is general to measure the color difference before and after heating and measure the amount of change. The color difference is 400 nm to 8
The transmittance in the visible light region up to 00 nm is measured before and after the heat resistance test, and the color difference after transmission is calculated. For example, when it is used as a color filter for liquid crystal display devices, 2
Color difference Δ when left for 1 hour in an atmosphere of 00 ° C
It is _sufficient to measure E _ab . In the present invention, this color difference is preferably 3 or less. This is because a color difference of 3 or less is almost invisible to the human eye.

Further, in the porous layer which has been colored, there are bores which are not completely filled with the dye. Therefore, it is preferable to apply a transparent substance as a surface protective layer in order to fill the remaining adsorption holes. In particular, when an epoxy monomer or epoxy oligomer is used to carry out a curing reaction, it is preferable because the dye can be applied without bleeding.

The surface protective layer strengthens the coloring layer having a relatively low hardness, imparts smoothness to the surface, and also acts as an oxygen barrier film.
It has a function of preventing oxidation even in a high temperature atmosphere which is exposed when forming the transparent conductive film, and preventing discoloration or deterioration of the colored layer. The coating thickness of the surface protective layer is preferably thinner than 2.0 μm after coating. If it is thicker than 2.0 μm, cracks and undulations are likely to occur, which affects the refractive index and the like.

A transparent electrode such as ITO and an alignment film are sequentially laminated on the surface protective layer by a known method, and a liquid crystal is injected between the electrode and another substrate having the alignment film to facilitate the process. The liquid crystal display element of the present invention can be obtained. In addition to the liquid crystal display device, the substrate with a color filter of the present invention can be used as various color CRTs, filters for printing, and the like.

[0027]

The binder used in the porous layer which is the ink receiving layer in the substrate with a color filter of the present invention can be dissolved in a water-soluble solvent having a high coatability at the time of coating, but after drying and curing. Has extremely high humidity resistance, and peeling of the porous layer hardly occurs even under high humidity. Therefore, the durability of the entire substrate with a color filter can be remarkably improved without substantially impairing the film forming property of the porous layer.

Further, in the substrate with a color filter of the present invention, the binder used for the porous layer which is the ink receiving layer has high heat resistance. That is, in the manufacturing process of the liquid crystal display element, the change in color difference is extremely small even after a high temperature process such as formation of a seal layer or an alignment film. Therefore, a substrate with a color filter having high color definition can be obtained as a liquid crystal display device substrate. Further, in the substrate with a color filter of the present invention, the amount of water remaining after forming the porous layer which is the ink receiving layer is smaller than that in the conventional case. Therefore, even when the organic resin protective layer is provided on the substrate with the color filter, there is an advantage that the light transmittance of the protective layer is not lowered.

From the above, when the substrate with a color filter of the present invention is used as a substrate of a liquid crystal display device, the resolution, sharpness, durability and the like of the liquid crystal display device are remarkably improved as compared with the conventional ones. Furthermore, when plastic is used as the substrate material in the substrate with a color filter of the present invention, a lightweight and compact plastic color liquid crystal display device can be obtained.

[0030]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. Examples 1 to 3 and Comparative Examples 1 and 2 6 parts of the resin shown in Table 1 was mixed with 100 parts by weight of pseudo-boehmite, and the film thickness after drying was 3. by spin coating.
Apply it to a glass substrate so that it has a thickness of 5 μm.
It was dried for 0 minutes and fixed to form a porous layer.

Next, a stripe pattern consisting of three colors of red, blue and green is formed on the porous layer by screen printing to form a colored layer, and then an epoxy resin (Epicoat 10 is used).
01: A coating liquid containing as a main component a trade name of Yuka Shell Epoxy Co., Ltd.) was spin-coated, heated at 150 ° C. for 1 hour, and cured to form a surface protective layer. For each of the obtained substrates with color filters, the transmittance in the visible light region (400 nm to 800 nm) was measured in advance, and then 2
The result obtained by placing in an oven at 00 ° C. for 1 hour, taking out, measuring the transmittance in the visible light region, and obtaining the color difference ΔE _ab is shown in Table 1.
As shown in.

[0032]

[Table 1] From the results of Table 1, in the substrate of the present invention using the heat resistant resin, the color difference was suppressed to 3 or less, whereas in the case of using the resin having poor heat resistance, the color difference significantly changed. Was confirmed. The parts in Table 1 are parts by weight.

Examples 4-7 and Comparative Examples 3-5. Samples were prepared in the same manner as in Example 1 using the various acetals shown in Table 2, and the results of evaluation of color difference, water resistance and film-forming property are shown in Table 2. The water resistance, film-forming property and degree of acetalization in Table 2 were measured as follows.

Water resistance evaluation After dipping in water for 1 day, a cross-cut tape test according to JIS K5400 was performed and evaluated according to the following criteria. Partly peeled off: ×, not peeled off: ○ Film formability evaluation Visually observing the presence or absence of cracks during drying,
The following criteria evaluated. ○: no crack, ×: crack

Accurately sample about 5 g of the acetalization degree sample into an Erlenmeyer flask and add 10 m of water.
1, 10 ml of isopropanol and 10 ml of n-butyl alcohol were added to each and shaken to dissolve the sample. After the sample was completely dissolved, 10 ml of N-hydroxylamine hydrochloride solution was added accurately, an overflow condenser was attached, and the mixture was heated on an electric heater for 60 minutes for reaction. After cooling the obtained reaction solution, bromphenol blue was added as an indicator to
Three drops were added, and 10N sodium hydroxide solution was added dropwise until the color of the solution changed to pale blue, and the degree of acetalization was determined by the following formula.

A = [1.42 × (ab) × f] × 100 / S × P Degree of acetalization (mol%) = A × 51.52 × 2/14
2 In the above formula, A is the amount of vinyl acetal (% by weight), S is the sampled amount (g), P is the solid content (%) of the sample, and a is the amount of the required 10N sodium hydroxide solution (ml). ) And b indicate the amount (ml) of the 10N sodium hydroxide solution required for the blank test, and f indicates the titer of the 10N sodium hydroxide solution.

[0037]

[Table 2] From the results in Table 2, it was confirmed that the performance greatly depends on the average value of R and the degree of acetalization.

Claims (5)

[Claims] 1. A color filter-provided substrate comprising a substrate on which a porous layer mainly composed of inorganic particles and a binder resin is provided, and a specific pattern is formed by coloring the porous layer, which is contained in the porous layer. A substrate with a color filter, characterized in that the binder resin contains, as a main component, at least one selected from the group consisting of polyvinyl acetal, amino resin, acrylic resin and modified products thereof. 2. The degree of polymerization of polyvinyl acetal is 300 to.
5,000, the degree of polymerization of amino resin and acrylic resin is 1
The color filter-attached substrate according to claim 1, which is from 00 to 2,000. 3. The substrate with a color filter according to claim 1, wherein the binder resin is a polyvinyl acetal represented by the following chemical formula 1. However, R in formula 1 is C _n H _{2n + 1,} the average value of n is 0.3 to 4.5. 4. A water-based coating liquid mainly composed of inorganic particles and at least one organic compound selected from the group consisting of polyvinyl acetal, condensable amino monomers and oligomers, and acrylic monomers and oligomers. A method for producing a substrate with a color filter, which comprises coating on a transparent substrate, drying or curing the organic compound so that it becomes a heat resistant resin, and then coloring it to form a specific pattern. 5. An electrode substrate with a color filter, which is formed by laminating a protective layer, a transparent electrode and an alignment film on the substrate with a color filter according to claim 1, and a transparent electrode and an alignment film on the substrate in order. Between the other electrode substrate provided with
A liquid crystal display element, which is an element sandwiching a liquid crystal layer, wherein at least one of the electrode substrates is a transparent electrode substrate.